CA2334894A1 - Regenerative adaptive fluid control - Google Patents

Abstract

A regenerative adaptive fluid motor control system integrating a load adapti ve fluid motor control system and a load adaptive energy regenerating system having an energy accumulator. The fluid motor control system includes a primary variable displacement pump (90) powering a spool valve (2) controlli ng a fluid motor (1) accumulating a load related energy. The load related energ y of the fluid motor is regenerated to provide a load adaptive exchange of energy between the fluid motor and the energy accumulator (122). This load adaptive exchange of energy is combined with a load adaptive primary energy supply for maximizing the over-all energy efficiency and performance potentials of the fluid motor control. The load adaptability is achieved by regulating the exhaust and supply fluid pressure drops across the spool valv e.

Description

REGENERATIVE ADAPTIVE FLUID CONTROL
Invent;ors Robemt M. ~isni.anr~ky, Brooklyn, Tiew York.
('l7) nssigneet ( ~:I. ) International Appln No.
(7?.) riJ.ede ((~3) This is related to U.S. application S.N.08/715,434 of of 09/18/96 ( issued as patent to a ) be WHICH IS A CIP OF 08/399,123 03/06/95 WHICH IS A CIP OF 08/075,288 ABAN

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(Zel'erenoc~s Ci~i;ed U . S . PATf;Nr t)OCUMJ:(Yf5 4,118.119 10/1978 Hegberg ..............060/431 WO 99/64?61 2 PCT/US98/12200 -3,882,896 5/1975 Budzich .........'.....09t/446 4,364,229 12/1982 Shiber ............... 06U/414 4,693.Of30~9/1987 Van Hooff ............ 060/417 2.924,910 2/1960 Covart~et al ......... 060/430 OTI-IER~ PUBLICATIONS
Lisniansky, Robert M.~~ "A~tomatika a Regulirovanie Gidravlicheskikh pressov:' Moskow: Mashinostroenie, 1975.
R EC~ENERAT = VE ADAPT I VE
FLUID CONTROL
This is related to U.S. a.pplication Serial No.08/715,434, filed 09/I8/96, to be issued as a patent, which is a continuation-in-part of application Serial No.
08/399,123; filed 03/06/95, now abandoned, which is a continuation-in-part of application Serial No.
08/075,288, filed 06/11/93, now abandoned, which is ..,.a continuation-in-part of application Serial No. 07/815,175, filed 12/31/1991, now abandoned, which is a continuation-in-part of application Serial No. v7/521,663, filed 5/10/1990, now abandoned, which is a continuation-in-part of application ,Serial No. 07/101,646, filed 1/25/1989, now abandoned, which is a continuation-in-part of application Serial No. 07/096,120, filed 9/14/198'x, now abandoned, which is a divisional of application Serial No. 06/737,063, filed 5/23/1985, now abandoned, which is a continuation-in-part of application Serial No. 06/704,325, filed 2/13/1985, now abandoned, which is a continuation-in=part of application Serial No. 06/318,672, filed 11/05/81, now abandoned.

FIELD OF THE INVENTION
The present invention.relates~primerily to a fluid motor position feedback control system, such as the electrohydraulic or hydromechanical position feedback control system, which includes a fluid motor, a primary variable displacement pump, and a spool type directional control valve being interposed between the motor and the pump and being modulated by a motor position feedback signal. More generally, this invention relates to the respective fluid motor output feedback control systems and to the respective fluid motor open-loop control systems. In a way of possible applications, this invention relates, in particular, to the hydraulic presses and the motor vehicles.
My copending international application on Regenerative Adaptive Fluid Control is identified by Serial No.
The largbr picture o= the Energy-Regenerating Adaptive.
Fluid Control Technology is..presented by my six U.S.applications .., identified ~by ~:'Seri~h;:Nttmbersv 08/:715,470; 08/716,4.74;' 08/715,434: 08/'710;:3"23;' 08/710,567; 08/725,056.
BACKGROUND ART: TWO MAJOR PROBLEMS
'.flre hyc9raul..tc .f luid motor ~is usual.ly driving a var.table .lotrci.
I n tire varisb:le load environments, the exhaust and supply f.i.uid pressu re drops across the directional control valve are ctmrged, which destroys the lj.nearit:y of a static speed charscteristio describing the fluid motor speed versus the valve spool displaoemsnt. As a result, a systss pin and the r~lat~d qualities, such as.th~ dynamio p~rfotmance aryl acouraay, zre all tl~a tunotions .ot tha vatiabls load.
Moreor~r. an en~r~,y ettioienoy of the position f~~dbaok control is also a function of the variable load.
The more the load rate and fluotuatior~, and the Higher the performance requirements, the more obvious are the limitations of the conventional fluid motor position feedback control systems.
In fact, the heavy loaded hydraulic motor is especially difficult tv deal with when several critical performance factors, such as the high speed, accuracy, and energy efficiency, as well as quiet operation, must be combined.
A hydraulic press is an impressive example of the heavy loaded hydraulic motor~m~ahaniss, The load conditions are chan;ed substantially within each press cirole,ineludins approaching the work. compressing the fluid, the working stroke' , decompressfeu tha fluid, and the ~rsturn stroke.
A more comprehensive study of the conventional fluid motor position feedback control systems can be found in numerous prior art patents and publications - see, for example s a) Johnson, J.E., "Electrohydraulic Servo Systems", Second Edition. Cleveland, Ohio r. Pentotl/jPC , 197.
b) Merritt,"H',E,, "Hydraulic Control.Systems".
New York - London - Sydney : John Wiley & Sons, Inc., 1967.
c) Lisniansky, R.M., "Avtomatika a Regulirovanie Gidravlicheskikh Presdov".
Moscow s Mashinostroenie, , 197.5 (this book had been published in Russian only).
The underlyins structural weakness of the conventional fluid motor position feedback control systems can be best characterized by sayirls that these systems are not adaptive to the changing lead envi~~nment,.
The problem of lead adaptability of the conventional electrohydraulic and hydromechanical position feedback contrv:
.systems can be more epecitically identified by analyZins t'~o typical hydraulic schematics.
The first typical hydraulic schematic incl~.rdes a three-gray directional control valve in combination with the two counteractive (expansible) chamber . ?he first of these chambers is controlled by said three-way vale which is alto oonneoted to the pressure and tank lines of the fluid power mean . The second cha~rber is under a relatively constant pressure provided by said pressure line. In this case, it is not possible to automatically maintain a supply fluid pressure drop across the three~~ray valve without a 'schematio operation ..
interference" Ni:h the ;.osition feedback control system.
Indeed, maintainini the supply fluid pressure drop can be achieved only by chansin~ the pressure line pressure, which is also applied to the second chaaber and, therefore, must be kept approximately constant.
The second typical schematic includes a tour-way directional control valve in combination with the two pounteractive chambess. loth o! these chambers are controlled by the four way valve which is also connected to the pressure and tank linea~o! the fluid power means. In this schematic, it is not possible to automatically maintain an exhaust fluid assure drop across the tour-way valve without encountering ~lications which can also'be dewed as a achesatic operation interference with the position feedback control eyetem. Indeed, a chamber's pressure signal which is needed for maintair~ru the exhaust fluid pressure drop, must be switched o~ from one chamber to the other in exact accordance with a vales spool trar~,!ition through a neutral spool position, where the chamber lines are switched over, to avoid damagiru th_e spool valve flow characteristics. I:~ add:sion. a -- pressure differential bet~een the :~~~ cha_-~.bers it the neutral spoil posi~ian gill affect the pr assure crop re~,clation an3 nay generate the dy-:zmic unstzbil!ty ~f the position feedback c=ntrol sy:tam.
" still' The problem of load adaptabili'y can ~rther identified by emphasisi:~g. a possible dynamic aperati:.~, i.~ae:!'erer.~_e bet~Yeen the ;.as' :ior. feedback ccn:rol and :hs re;ulition of the exhaust and supply fluid p-as:rre drips.
The problem of load adaptability can be still further identified by emphasizing a possible pressure drop regulation interference between the supply and exhaust line pressure drop feedback control systems.
The structural weakness of the conventional fluid motor position feedback cowtrol~sys~tems can be still further characterized by that these systems are not equiped for regenerating a load related energy, such as a kinetic energy o.f a load mass or a compressed fluid energy of the fluid motor-cylinder. As a result, this load related energy is normally lost. The problem of load adaptive regeneration of energy is actually correlated with the problem of load adaptability of the fluid motor position feedback control system, as it will be illustrated later.
Speaking ih general, the problem of load adaptability and the problem of load adaptive regeneration of energy are 'two mayor and interconnected problems which are to be solved consecutively by this invention, in order to create a regenerative adaptive fluid motor position feedback control system and, finally, in order to create a regenerative adaptive fluid motor output feedback control system and a regenerative adaptive fluid motor open-loop cont~o). system.

WO 99/64761 ,~ PCT/US98/12200 -SUMMARY OF THE INVENTION
The present invention is primarily aimed to improverthec~
qualities and energy efficiency of the fluid motor Dosition feedback control system, such as the electrohydraulic or hydromechanical position feedback control system, operating usually in the variable load environment .
The improvement of performance qualities, such as the dynamic performance and accuracy, is the first concern of this invention, while the improvement of energy efficiency is the second but closely related concern.
This principal object is achieved by s (a) shaping and typically linearizing the now characteris-tics of the directional control valve by regulating the supply and exhaust fluid pressure drops across this valve s (b) regulating the hydraulic fluid power delivered to the directional control valve, in accordance with, but above,~hat is required by the fluid motor r {c) preventing n schematic operation interference betXeen the regulation of said pressure drops and the position feedback control s (d) preventing . n dynamic operation interference between the regulation of said pressure drops and the position feedback control (as it will be explained later);
(e) preventing a pressure drop regulation interference between the supply and exhaust line pressure drop. feedback control systems (as it will also be explained later).
The implementation of these interrelated stops and conditions is a way .of transition from the cvnvent.ional fluid motor position feedback control systems to the load adaptive fluid motor position feedback control systems. .These load adaptive systems can generally be classified by the amount of controlled and loadable chambers of the fluid motor, by the spool valve design ccntigurations~ and by the actual.shape of the spool valve fl~w characteristics.

WO 99/64761 g PCT/US98/12200 -In a case when or.=y o:~e of t~~o counteractive chambers cf :h.s fluid motor i~~contrallable, the fluid motor can be loaded o~,y iri one directian. The controlled chamber is connoeted to the three-way spool valve which also has a supp:~
power line and an exhaust power line. In this car s, the second ehaa~ber is under a relatively cot>stant pressure supplied by an independent source of fluid power.
In a case ~~hen both chambers ace controllable, the fluid motor can be loaded in only one or in both direotione.
The controlled chambers are connected to a five-way spool valve which also has a common~supply power line and tyro separate exhaust power lines.. Then the Iluid rotor is loaded in only one direetion.'only one of too exhaust lines is also a cbunterpressure line. . Then the fluid motor is loaded in both directiocv, both exhaust lines are used as counterpressure lines.
Usint the three-way or five-way spool valve with a separate exhaust line for each controllable chamber.
malce~ it possible to prevent a schematic operation interference bet~Neen the position fs~dback control and~the re6ulation. of-pressure drops. In particular, the problem of measurins a chamber's pressure sisnal i9 elimirv~ted.
Each counterpressure line is provided pith an exhaust Line pressure drop resulator;which is modulated by an exhaust line pressuro drop feedback sisnal which is noasured between this count~rpresst~.re line and the relat~_chamber.
In tho prooess o! maintaining tho eu~~y !laid pressure drop across tho spool valve, a supply fluid tlo~r rate is be,ina moni-tored continuously by the primary variale displacement pump of the fluid power means. Maintaining the supply fluid pressure drop is also a way of regulating the hydraulic power delivered to the spool type directional control valve.

In the process :.: maintaining the exhaust fluid pressure ~r~~
across the spool v~ ve, all the tlo~r is beins released from the counterpressur~ 1!.~.e ~hr~ugh the exhaust line pr~ssur~
drbp regulator zo the tank. Counterpressure miy be created in the counterpressure line only tar a short time while the hydraulic fluid in the preloaded chsmber is being decompressed. However, .the control over the decompression is critically important for improving the system's dynamic performance potential.
A family of load adaptive fluid position servomechanisms may include the three-, four-, five-, and six-way directional valves.
The three-way spool valve is used to provide the individudi pressure and count~rpressure lines for .only one controllable -chamber. The six-way spool valve is used to provide the separate supply and exhaust lines for each of two controllable chambers.
The five-way spool valve can be derived from the six-way spool valve by connecting together t'~o sepa.rate supply Lines.
The tour-~~ay spool valve can be derived from the five-way spool valve by connecting together tXO separate exhaust lines.
':he four-way spool valve does create a problem of ~ ~ schematic operation interference between the position feedback control and the regulation of pressure drops, as it is already explained above.
However. the principal possibility of using the four-way spoo'_ valve in the adaptive posi~tio~ servomechanisms is not excluded.
What: is in common for the adaptive fluid position servomechanis~rs being considered is that the fluid motor is provided ~~rith at Least cne controlled ind Z~adable cbaa~ber, and that thin chamber is provided Xith the pressure-compensa-ted spool valve flow characteristics. These pressure-compensated flow characteristics are shaped by the related exhaust line pressure drop feedback control system which includes the exhaust line pressure drop regulator and by the related supply line pressure drop feedback control system which includes the primary variable displacement pump.
The desired (Linear or unlinear) shape of the spool valve flow characteristics is actually implemented by programming the supply and exhaust line pressure drop command signal3 of the supply and exhaust line pressure drop feedback control systems, respectively. Some possible principals of programming these command signals are Illustrated below.
(1) The supply and exhaust line pressure drop command signals are set approximately constant for linearizing the pressure-compensated spool valve flow characteristics. fhe related adaptive hydraulic (electrohydraulic or hydromechariical) position servomechanismsc can be referred to as the linear adaptive servomechanisms, or as the fully-compensated adaptive servomechanisms. Still other method of programming the pressure drop command signals can be specified with respect to the linear adaptive servomechanisms, as it is illustrated below--by points 2 to 5.

(7) 'the supply line pressure drop command signal is being increased slightly as the respective load pressure rate is increased, so that to provide at least some over-compensatlon ~~l.ong the supply power line.
(3) The supply line pressure drop command signal is being reduced s.l.ightly as the respective load pressure rate is increased, so that to provide at .Least some under-compens<~lion along the supply power line.
(4) The exhaust line pressure drop command signal is b~:ing increased slightly as the respective load pressure rate is increased, so that to provide nt la?ast'some under-compensation along l:he exhaust power line.
(5) The exhaust line pressure drop c~mmand signal is being reduced slightly as the respective load pressure rate is increased, so that to provide at .Least some over-compensation along the exhaust power line.
Lt is understood that the choice of flow characteristics do not effect the basic structure and operation of the load adaptive fluid motor control systems. For this reason and Without the loss of generality, in the following detailed description, the linear adaptive servomechanisms are basically considered.
It is a further object of this invention to develop a concept of load adaptive~regeneration of a load related energy, such as a kinetic energy of a load mass or a compressed fluid energy of the fluid motor-cylinder. This is achieved by replacing the exhaust line pressure drop regulator by a counterpresaure varying and energy recupturing means ~sueh as :gin exhs~ust line variable displacement motor or an exhaust line constant displacement motor driving an exhaust line variable displacement pump~~by replacing the exhaust line pressure drop feedback control system by an energy recupturing pressure drop feedback control system, and finally, by creating a load adaptive energy regenerating system including fluid motor and load means and energy accumulating means.
I t i.s st.i l.l. further object of this inventiion to develop a c:~ncept of load adaptive exchange of energy between the fluid moty~r and load means and the energy accumulating means of the lu~d adaptive energy regenerating system. The load adaptive regeneration of the load related energy of the fluid motor and load means can be viewed as a part (or as a larger part) of a ~omplet,e circle of the load adaptive exchange of energy between i.He fluid motor and load means and the energy accumulating means.
It is still further object of this invention to develop a. regenera.tive~adap~tive fluid motor position feedback control system which is an integrated system combining the load adaptive fluid motor position feedback control system and 'the load adaptive energy regenerating system.
It is still further object of this invention to develop a regenerative adaptive fluid motor out put feedback control system and a regenerative adaptive fluid motor open-loop control system. In general, the regenerative adaptive fluid control rnalces i~t possible t ,o combine 'the Load adalotive primary power supply and the load adaptive regeneration of energy for ms.ximizing the over-all energy efficiency snd performance potewti.als~ of 'the fluid motor control. systems.
It is s till furtloer object of; this invention to develop the high energy-efficient; J.oad adaptive hydraulic presses utilising ~I:he regenerative adaptive fluid control.
It is still further object of 'this invention to develop I:he high energy-efficient, load adaptive motor vehicles utilizing 'the regenerative adaptive fluid control.
It is still further object of 'this invention to develop 'the high energy-efficient, load ~adap~tive City 'fra.nsit Brxses r.itl.li.zing the regenerative adaptive fluid contr.ol..
Further objects, advantages, and futures of this invention will be apparent from the follo~Ning detailed description when read in conduction with the drawings.
I3RICr D1;SCRTPTION Or T11C DRhWINGS
Fig. l sho~rs the adaptive . fluid s ervomeehanism having only or.~ controllable chamber.
Pia.2 ~ho~s a pow~~ ~upplY schematic version.' Fig.j-A is a generalization of Fig. 1.
fig~3-E1 illustrates the flow characteristics of valve 2.
pi'.~ chows the adaptive fluid servomechanism having too controllable chaarben but loadabl~ only in one direction.
Fig. ~-A is a generalization of Fig.l~.
Fig.-D illustrates the flow characteristics of valve 2.
Fig.G shows the adaptive fluid servomechrinism having two cantrollable chambers and Inedible in both directions.
1'.lg.'7-A is a. generalization of Flg.6. ~ ' 1'J.g.'7-B illustrates the floor characteristics of valve 2.
fi~.A ~howe a genersllsed model of adaptive fluid position ~ecvomechinism~. ' f'ig.~I Illustrates the. concept of road adaptive regeneration of energy.

WO 99/64761 i 3 PCT/US98/12200 -1'ig.lU shows the adaptive fluid servomechanism having.
,.a built-.in energy regenerating circuitry. ' r.tg.l1 SItUW8 the adaptive fluid servomechanism having an independent energy regenerating circuitry.
~'ip.l2 is a modification of Yig.l.l. for the hydraulic press type applications.
Fig. l3 shows a generalized model of the regenerative adaptive fluid motor output feedback control systems. ' Fig.l<< show9 a generalized model of the regenerative adaptive fluid motor velocity feedbacfc control systems.
Fig. l.5 shows a generalized model of the regenerative adaptive fluid motor open-loop control systems.
Fltt.Jd is a modification of Fig.ll for the.motor v~hiele type applications. .
t~iy..l.'7 shows a regenerative adaptive drive system for the motor vehicle type application s.
F'i.c~ . .1 f1 shows a regenerative adaptive drive system having a hydraulic accumulator.
E'ig.J.9 shows a regenerative adaptive drive system having the combined energy, regenerative means.
t'tcJ.2U :;bows a regerrerat:ive adaptive drive system having a variable disp.l.acement motor driving the load.
I~.ic~.7.1 shows a regenerative adaptive drive system having a regenerative braking pump.
F.ig. J2 slrc~ws a modified regenerative syRtem having a i~yd rau 1 is accumula for .
t. ig.2.:a shows t:he load adaptive c9isplacement mearrfr of. t:he as.r.ist:ing supply lane pressure drop feedback control system.
t'ig.2~l shows the load adaptive displacement means of the energy recupturing pressure drop feedback control system.
t~ig.25 il.1ustrates a stop-and-go energy regenerating circ.la.
fig.26 shows a modified regenerative system having the combined energy regenerating means.
Fig.27 shows a generalized regenerative system hav3.ng a built-in regenerating circuitry.
Fig.28 shows a regenerative adaptive drive system having a supplementary output motor.
Fig.29 shows a generalized regenerative system having a supplementary output motor.

DESCRIPTION OF THE INVENTION
rI?NERAL LAYOUT AND '1HEORY
Introduction: Adaptive fluid yosition feedback control.
f:i.g..l shows a simplified schematic of the load adaptive fluid motor position feedback control. system having only one controllable chamber. The moving part 21 of the fluid motor-cylinder I is driven by two counteractive expansible chambers - chambers 10 and 11, only one of which - chamber ih -Is controllable and can be loaded. The second chamber -chamber il - is under a relatively low (and constant) pressure Po supplied by an independent pressure source. This schematic i.s developed primarily for the hydraulic press type aplulications.
As it: is already mentioned above, the load conditions are r:hanc~ed substantially within each press circle including approaching the work, compressing the fluid (in chamber lU), the working struck, decompressing the fluid (in chamber 1U), and the return strocli.
The schematic of E'ig.l further includes the hydraulic power supply rneans 3-1 having a primary variable displacement pump po~srins the pressure lina~ sl., Tha three-ray spool--type directional control valve 2 ii provided with th.re~
hydraulic power lines includins a motor line -. line Ll -. connaoted to line is of chs~bar 10 , the supply power line L2 connaotad to pressure line sl , and the exhaust power line L3.
Lines L2 and L3 era commutated with line L1 by the spool vslve 2. To consider a.ll the picture. ITig.J. should be atWied together with the relt~ted-supplementarry figures Z, 3-A, and 3-13.
The block 4 represents a generalized model of the optional position feedback control means. This block is needed to actually make-up the fluid motor position feedback control ay~s~sm, which.is capable of regulating the motor position Xl of motor 1 by employing the motor position feedback signal CX1, where coefficient "C" is, usually, constant. The motor position feedback signal CX1 is generated.tiy a motor position sensor, which is included into block << and is connected to the moving part 21 of the hydraulic fluid motor 1.
An original position feedback control error signal ~.Xor is produced as a difference between the position.lnput-command signal Xo and the motor position feedback signal CX1.
There are at least two typical fluid motor position feedback control systems - the electrohydraulio and hydromechanical position feedback control systems. In the electrohydraulic system, the equation ,~,Xvr~ Xo-~1 or. the like is simulated by electrical means located within block 4.
In the hydromechanical s'ystdm, the equation L~Xo~ Xo - CXl or the like is simulated by mechanical means located within block 4.
The block 4 may also include the electrical and hydraulic amplifiers, an electrical torque motor, the stabili~ati~n -- optimization technique and other components to properly amplify and condition said signal L~Xor for modulating said valve 2. In other words, the original position feedback control error signal Q Xor is finally translated into a manipulated position feedback control error signal 0 X which can be identified with the valve spool displacement D X from the neutral spool position ~.X - 0.
~ m~ulated In general, it can be.said that the position feedback control error signal ~ X is derived in accordance with a difference between the position input-command signal Xo and the output position signal X1. At the balance of the position feedback control s ~Xor X.v.- CXi'= 0 and,: hence, ~X~O.
On the other hand: and for simplicity,lit can also be often assumed that a X =.X o-- CXl This principal characterization of the optional position feedback control means is, in fact, well known in the prior art and will be extended to still further details later.

The exhaust line pressure drop regulator 3-3 is introduced to make up tha exhaust line pressure drop feedback control system which is capable of regulating the exhaust fluid pressure drop across valve 2 by varying the countsrpre~sure rate P3 in the exhaust po.~er Iine~L3. This exhaust fluid pressure drop is represented by the exhaust line pressure drop feedback signal, Nhich is equal P03 - P3 and is measured between the exhaust poorer line L3 and the related exhaust signal line SL3 corv~ected to line Ll.
The regulator 3-3 is connected to the exhaust power line L3 and to the tank line s2 and i~ modulated by an exhaust line prie~uri drop tiedbaelc control error ei~nal, which is produced in accordance with a difference between the e~chaust line pressure drop commaryd ~isnal L1 P3 and the exhaust line pressure drop feedback signal P03 ~
'rhe primary variable displacement pump of fluid power supply mans 3-1 ( pump 58 on Pig.2 ) is introduced to make-up the supply line pressure drop feedback control system, ~rhich is capable of regulating the supply fluid pressure drop acro~~
valve 2 by varying the pressure rate P2 in the supply poAer line L2 by varying the supply fluid flow rate in said line L2 by said variable di~placeo~nt pump. This supply fluid pres-sure drop i~ represented by the supply line pressure drop feedback sigtul, which is equal P2~ P0Z and is measured betty en line L2 (through line 32 on Fig.2)and the related ~~~llne s L2 connected to line Ll. A variable delivery means 56 of pump 58 is modulated by a supply line pressure drop feedback control error sisal, which is produced in aaoordanoe with a difference bet~reen the supply line pressure drop eoamand signal 0 P2 and the supply line pressure drop feedback ' signal P2 ~ p02 ' The schematic show n on Pi~.l operates z~ follows.
At the balance of the motor position feedback~control ~X = Xo- CX1- 0. Nhen the hydraulic fluid motor 1 is WO 99/64761 1 ~ PGTNS98/12200 -moving from the one position X1 to the other, thi motor .
speed is d.etined by the valve spool displacement ~ X s X - CX

from the neutral spool position (~X ~r 0. The systes performance potential is substantially improved by providing the linearity of the spool v~ w flog characteristic P w K1 ~ X . «llere K1 is the constant coetticient,and P is the fluid ilo~K rate to C gin ) or the fluid flo~.rate from rout ) the controllable chamber 10. This linearity i~
achieved by applying the supply line pressure drop command signal 0 pz = constant and the euhaust line pressure drop command s igtul ~ P3 - cons taut to the supply line pressure drop feedback control system and the e~chaust li~e pressure drop feedback control system, respectively.
The pres~ur~ maintained in the supply power line L2 by the supply line pressure drop te~edback control system la p2 - p02 ~ 0 p2 ~d can be dust slightly above what is required !or chamber 10 to overcame the load.
On the other hand, the counterpressure maintained in the exhaust power line Lj by the exhaust line pressure drop feedback control system is p3 ; P03 -- ~ P3 and can be fust slightly below the pressure P03 ~ p02 in chasber 10 .
However, there are some limits for acceptable reduction of the pressure drop command signals 0 P2 and 0 p3 The pressure drop commaxid signals D~PZ and ~P3 , the pressure Po and their interrelationship are seleoted for linearising the spool valve flow charsoteristic ( r ra K1,~ X ) Without "runnins a risk" o! hill decompressing the hydraulic motor ( chuber 10 ) and genentins the hydraulio spooks in the hydraulic system. Some of the related considerations are ~ ,., 1. The pressure po has.to compress the hydraulic fluid in chamber 10 to such an extent as to prevent the hill deovmpression under the dynamio operation conditions. ' In the absence of static and dynamic loading, the pressure p10 in chamber 10 is fixed by the pressure Po applied to chamber 11 so that PiQ- Ko Po , ~~here Ko is the'constant coefficient.
2. The pressure drop command signal ~,P3 is selected as ~ ~~ Q P3 ~r P10 ~ Ko Po ' Under this condition,the pressure drop Fp3 P] "' ~ P]
can be maintained even during the return stroke.
Indeed. after decompressing the prsloaded chamber 10, the regulator ]~] is open ( ,P]-- 0 ),. but the pressure drop PO] - 0 ~ OP] ._~_ Ka Po is. still maintained simply by appro:imately constant pressure Po .
3~ It the presages of the spool valve 2 are symmetrical relative to the point 0 X ~ 0, the pressure drop command signals ~PZ and ,~P3 are to be approximately equal.
In this case , ~P2 = OP] = P10 ° Ko Po = i2m_in , (1) wtiere ~ ~ P2~n is the minimum pressure rate maintained in line L2 by the supply line pressure drop feedback control system.
4. The smaller pressure drop command sigruls L~ Pz and ,(~p3 , the lu-ger spool valve 2 is required to conduct the given fJ.uid now rate.
The regulator 3-3 is opened by a force of the spring shown on Fig.l and is being closed to provide the counterpressure P3 only after the actual pressure drop P~3--..p] exceeds ita preinstalled value O P3 . which is defined by the spring force.
Practically, at the~very beginnins of the return stroke, Then the regulator ]-] has to enter into the operation, the controllable chamber 10 is still under the pressure.
It means that regulator ]-] is prelia~narily closed and is ready to provide the counterprsssure P] , ~rhieh is being maintained by regulator ]-] only for a short time or decompressing chamber 10. Ho~wer.the oontrol over the decompression i.s critically important for i,provin~ the system's dynamic performance potential.

The schematic of Fig. 2 is a disclosure of block 3-1 shown on Fig. 1. This schematic includes the primary variable displacement pump 58, which is connected through line 30 and check valve 44 to the pressure line 51.
h relatively low pressure, high capaca ty fluid power supply- 50 ( such as a centrifugal pump) is also connected through line $4 and check valve 40 to the pressure Line 51.
The primary motors ~ such as electrical motors driving the pumps are not sho.vn on Pig.2. The variable delivery means 56 of pumF 58 includes a variable displacement mechanism of this pump. The tank lines ~2 and 36 are collected by the oil tank 62. The pressure line 51 can be protected by the maximum pressure relief valve Which is not shown on Pig.2.
The maximum pressure in line 31 can also be restricted by using the variable delivery means 56 or pump 58.
In ~ceneral, the maximum Pressure relief valves can also be used to protect other hydraulic line.
In accordance with Fig.2, a relatively low pressure fluid froth the high capacit y fluid power supply 50 is introduced through check valve yv into the pressure line 51 to increaa~ the speed limit of the hydraulic cylinder 1 ( Fig.l ), as the pressure rate in line 51 is sufficiently declined. Actually, the hydraulic poser supply 50 is being entered into the operation ~uat after the spool of valve 2 passes its critical point, beyond Nhich the pressure PZ in line 51 is dropped below the minimum regulated pressure f2min ' The schematic shown on Pig.l is assy~gmetrical,relative to the~chambers 10 and 11. The functional operation of this schematic can be still better visualized by considering its generalized model,which is presented on -ig.3-A and is accompanied by the related pressure-compensated flow chara-cteristic PI~K10X of valve 2. ?he fluid power means 3 shown on Fig.3-A, combine the fluid power supply means 3-1 . and the regulators 3-3 , which are shown on Fig~1~

WO 99/64761 2o PCT/US98/12200 -The concept of preventing a substantial schematic operation interference.
Fig.4 shows a simplified schematic of the load adaptive fluid motor position feedback control system hrwing two controllable chambers but loadable only in one direction. This ~cl~ematic is also developed primarily for the hydraulic press type applications, is provided with the five-way spool valve 2, and is easi.l y understood when compared wi th F'ig . 1 . The .L ine 12 0l' chamber 11 is connected to line L~ of valve 1. The loadable chamber 10 is controlled as before. 'fhe chamber 11 is commutated by valve 7 with the supply power.line Lti and wii:h the "unregulated" separate exhau.:t line L5. !'he supply power line L6 is connected to line L2 but is also considered to be "unregulated", because the supply signal line SL2 is communicated (connected) only with chamber 10. the exhaust line L5 is, in fact, the tank line. In this case, equation (1) can be generalized as:
0 ~2 = ~ P3 _ P10 = P11- P2min ( ) where r P10 and Pll are the pressures in chambers and 11, respectively, at the absence of static and dynamic loading.
The pressures P10 and P11 have to be high enough to prevent the full decompression of chambers 10 and 11 under the dytumic operation conditions. On the other hand, the pressure drop command signals ~ PZ and ~ P3 have to be small enough to improve the system energy efficiency.
The schematic shown on Fig.4 is assymmetrical,relative to the chambers 10 and 11. The functional operation of this schematic can be still better visualized by considering its generalized model, which i~ presented on Fig.S-A and is accompanied 'by the related flow characteristics F10' '~1 ~X
and F1~ ~ K1~ ~ X of valve 2. The first of these flow characteristics is pressure-compensated. The fluid power means 3 shown on Fig.S-A, combine the fluid power supply means 3-1 and the regulator 3-3 , whzch are shown on Fig.4.
The schematic shown on Fig.6 ~ . is related to the load adaptive hydraulic position servomechanism having t'wo controllable chambers and ~loadabl.s in both directions.
This schematic is provided with the five-way spool valve and is easily understood when compared with Fig.4. Z'he ,.
loadable chamber 10 is controlled as beZore except that the supply signal line SL2 i~ communicated ( commutated ) with chamber 10 through , .. check valve s. Ths second loadable chamber - chamber 11 - is commutated by valve 2 with the supply power line,L6 and with the exhaust power line LS~ The line L6 is connected to line IZ. Ths supply signal line SL2 i~ aho communicated ( commutated ) with chamber 11 through check valve 6.
The e~chaust line Ls i~~ a sepanta counterpresaure line which is provided with an additional e~cttaust line prea~ure drop feedback control system including an additional ezhaust line pressure drop regulator 3-4 which is shown on Fig.6.: The related exhaust signal line SL5 tranaaitting signal Pas ,ia connected to line 12 0!
chamber 11. The counterpreasure maintained in line L5 by the additional exhaust line pressure drop feedback control system, is s PS .= POS -- 4, Ps , where 0 Ps is the related pressure drop command signal.
The check vaivs logic makes it possible for the line SLZ to select ~ one of two chambers, whichever has the higher pressure 'rate, causing no problem for maitaining the supply fluid pressure drop across valve 2, as well as for the dynamic stability of the fluid motor position feedback control system.
A very small throttle valve ly connecting line SLa with the tank line 52, is helpfull in extracting signal Pp2 .
The schematic shown on Pig.6 is symmetrical,rslative to the chambers 10 and 11. The functional operation of this schematic can be still better visualized by considering its generalized model, which is presented on Ptg.?-A and is accompanied by the related pressure-compensated flow .
characteristics F10= Kl OX and P11= - K1 D X of valve 2.
The fluid power means 3 shown on Pig.? -A, combine the fluid power supply means 3-1, the regulators 3 -3. 3-4. and the small throttle valve l9,which are shown on Fig.6.
Of course, the linear flow characteristics shown on Fig.3-H, Fig.-H, and Fig.7- H, are only the approximations of the practically expeoted flow characteristics of valve 2 , while they are not saturated.
The motor load which is not shown on the previous schematics, is applied to the moving part 2l of the hydraulic fluid motor 1. 'This load is usually a variable load, in terms of its magnitude and (or) direction, and may aenarally include the static and dynamic components. The statio loading components are the one-diirectional or two-directional forces.
The dynamic (inertia) loading component is produced by accelerating and decelerating a load mass (including the mass of moving part 21) and is usually a - two-directional force. If the fluid motor 1 is loaded mainly only in one direction by a static force, the schematic of Fig.l or Pig.4 is llkely to be selected.
If the fluid motor 1 is loaded substantially in both directions by the static forces , the schematic of Pic.6 is more.iikely to be used.
What is in common for schematics showri on Fig.3-A, Fig.5-A, and Fig.7-A, is that fluid motor 1 is provided with at least one controlled and loadable chamber, and that this chamber is provided with the pressure-compensated spool valve flow characteristics: This idea can be best illustrated by a model of Fig.B which is a general3.zation of Fig.3-A, Fig.5-A, WO 99/b4761 23 PCT/US98/12100 and Fig.7-A. The block 5 of Fig..8 combines fluid motor means (the fluid motor 1) and spool valve means (the spool valve 2), which are shown on previous schematics.
It is understood that load adaptive fluid motor position feedback control systems being considered are not limited to the hydraulic press type applications. As the supply and exhaus lines L2, L3, L5, G6 are commutated with the chamber lines L1 L9, the related signal lines Su, gL3, Sts, SL6 aQUSt be communicated accordingly with the came chamber lines L1, L~.
The cammunicati~n ~f si~nal~Lines S L2, SLj, Sts, S L6 with the chambers can be provided by eonneotins or cosisutating these signal lines with the chambers. Having the separate supply and exhaust power lines for each controllable chamber, as well as having only one loadable chamber, makes it possible Lo eliminate the need for commutating these signal lines.
Finally, it can be concluded that:
1. Providing a separate exhaust power line for each controllable chamber is a basic precondition for preventing a substantial schematic operation interference between the pressure drop feedback control systems and the fluid motor position feedback control system . Thi.s schematic operation interference may lead to the dynamic instability of the fluid motor position feedback control system, as it was already explained before.
2. By virtue of providing the separate exhaust power lines L3 and L5, the need for commutating the related signal line SL3 end SL5 is eliminated, as it is illustrated by figures 4 and 6.
3. In a case of having only one controllable chamber, the commutation of supply signal .line SL2 is not needed, as it is illustrated by Fig. 1.
4. In a case of having only one loadable chamber, the commutation of supply signal line SL2 can be avoided, as .it is illustrated by Fig.4.
In a case of having two l.oadable chambers, the ' commutation of supply signal line SL2 can be accomplished by suc:l~ commutators as follows:
(a) the commutator using check valves 5 and 6, and being operat:ecj by the pressure differential between the power l~.nes of motor 1, as it is illustrated by rig.6 (b) '' the commutator using an additional directional control valve which is operated by the spool of valve 7.
6. In accordance with.point 5,~
the schematic of Fig.6 can be modified by replacing the first-named commutator by the second-named commutato.r.
'1'lre moo9.t.tiec9 schematic is of a very general nature anc3 is appl.ic:able to the complex load environments.
Position feedback control means.
It should be noted that ' transition from the c=:~'rentioral f?uid position servomechanisms to the load a~artive f'_:rid position servomechanisms does not change the par': of The system which is outlined by block ~.
':he optional physical structure of the position feedback control means is disclosed in numerous prior art patents and publications describing the conventional fluid motor position feedback control systems and the related position feedback control technique - see, for .example, the above named books and also s a) Davis, S.A., and B.K. Ledger~rood, "Electromechanical ~omponent~ ror Servomechanisms" Ifsw York s McCraw-Hill, 1961.
b) Wilson, D.R.. Ed., "Modern Practice in Servo Design':
Oxford-New York-Toronto-Sydney-8raunsehweig Pergamon Press, 190.
c) Analog Devices, Inc., "Analog-Digital Conversion Handbook", Edited by Sheingold D.H., Third Edition.
Englewood Cliff . N.J.r Prentice-Nall, 1986.
d) D'Souza, A.F., "Design of control systems".
EnPlewood Cliffs, 1V.J.r Prentice-Hall, 1988.
It should also be noted that the electrical position feadbaok control oirouitry of eleetrohydraulic poaitivn servomechanisms is quite similar to that of electromecha-nical~l~~~ariiama. It is to say that in the case of electrohydraulic position servomechanism , the electrical portion of block 4 - including the optional position sensor but excluding the electrical torque motor - can also be characterize by the analogy with the comparable portion of the electric motor position feedback control systems -ace, for example, the books already named above.
In accordance with the prior art patents and publications, the above brief description of block 4 is further emphasized and extended by the comments as follows , .
1~ The motor position Xl is the position of moving part cl (piston, shaft and so on) of thi fluid motor 1. In fact, the motor. position X1 can also be viewed as a mechanical signal - the output position signal of the fluid motor position feedback control system being considered.
2~ The motor position Xl is measured by the position feedback control means due to the position sensor, which is included into block 4 and is connected to the moving part _:
of the fluid motor 1.
3~ In the el~ctr~hydraulic position servomechanisms, an electromechanical position sensor can be analog or digital.
The analog position sensor, employs an analog transducer, such as a linear variable differential transformer, a synchro transformer, a resolver and so on. The digital positian sensor may include a digital transducer, such as an optical encorder. The digital positionsensor~can also be introduced by an analog-digital combination, such as the resolver and the resolver-to-digital converter - see, for example, chapter 14 of the above~rramed book of Analog devices, I..~.c.
u. It is to say that in the electrohydraulic, analog or digital, position servomechanisms, the motor position feedback signal CX1 ( or the like ) is generated by the electromechan-ical sensor in a form of the electrical, analog or digital, signal, respectively.

5. It is also to say that in ths.electrohydraulic, analag or digital, position servomechanisms, the position fnput--command signal Xo is also the electrical, analog or digital, signal, respectively. The position input-command signal Xo can be generated by a variety of components - from a simple potentiometer to a computer.
6. In the hydromschanical position servomechanisms.
the mechanical position sensor is simply a mechanical connection to the moving part 21 of the fluid motor 1.
in this case, the motor position feedback signal CXl is a mechanical signal. The, position input-command signal Xo is also a mechanical signal.
7. In accordance with explanations given previously s (a) the original position feedback control error signal 0 Xor is produced as a difference between the position input-command signal Xo and the motor position feedback ~siRnal CXl :
(b) the original position feedback control error signal Q X is finally translated into the or manipulated position feedback control error signal D X ;
(c) it can be said that the manipulated position feedback control error signal OX is derived in accordance with a'difference between the position input-command signal Xo and the output position signal X1t , (d) the manipulated feedback control error signal O X is a mechanical signal, which is identified with the spool displacement of valve 2 from the neutral spool position A X ~ 0.

8. In the electrohydraulic position servomechanisms, the spool of valve 2 is most often actuated through the hydraulic amplifier of the position feedback control means.
The spool valve 2, the hydraulic amplifier, and the electrical torque motor are usually ~ntsgrated into what is called an "electrohydraulic servovalve".
g. In the hydromechanical position servomechanisms, the spool of valve 2 is also most often actuated through the hydraulic amplifier ~of the position feedback control means.
The spool valve 2 and the hydraulic amplifier are usually WO 99/64761 2,~ PCT/US98/12200 -integrated into what is called a "servovalve"
10. S till more comprehensive descriptioon of the optional position feedback control means ( block 4 ) can be found in the prior art patent' and publications including the books already named above.
I~ concept of load adaptive regeneration of enerQV.
In applications. like ai~hn~i ed etiort_strolto hydraulic dresses. where s associated wilg the cospressed hydraulic fluid is substantial in defining the system ener~yr ett:cieney, a regeneration of this energy can bra justified. tig.9 is originated by combining Fig.l and Fig.2. However, the rs~ulator 3-3 is replaced by a variable displacement rotor 65 havit~ a variable displacement means 6~, a pressure line ~?, and a tank line ?3~
The motor 6 5 is connected through line ~~ to line L3 ~d has a 'comwn shaft ' ~Z with l.hs variable displacement pulp s8.
The vsriable displaeeme mew 67 is modulated by the exhaust line pressure dr~~~~~1, which is equal p and is areasured between the exhaust power line L3 {through line 75) and the related signal line SL3.
a back The ~~chaust line pressure dr a n of ~yxt~~ tncluding motor 65, maintains the e~chau~t fluid Dresaure drop !O3 - p~ aososs'spool naive =
by vsrying the counterpressure p~ ~ l03 O r3 in the ~~chaust line L3 by the variable displacement means 6?.
A flywheel 94 is attached to the shaft 7Z and is dri~ten by motor 65. The pusp se is generally driven ~yl'~
motor 100, by the motor 65 and by the~tly~rhesl 94.
As a result, the potentisl energy o! the fluid eo~pr~~~ed in chamber 10 and, hence, the exhaust fluid ener~r of the ~_xhaust fluid flow passim through line Lj , i~ converted into a kinetic energy of motor bs and the related rotated mass including flywheel 94. This kinetic energy is finally WO 99/64761 2g PCT/ITS98/12200 -r~us~d through the supply power line IZ by th1 supply line pr~~sur~ drop f~~dback control sy~t~m. .
Fig.9~.also shows the frame 190 ( of hydraulic press 192 ag~.inst which the chamber 10 of cylinder 1 is loaded.
The concept of load adaptive regeneration of energy is further illustrated by considering the load adaptive, position feedback controlled, variable speed drive systems for the motor vehicle type applications (see figures 10 and 11), where a kinetic energy associated with a mass of the motor vehicle is substantial in defining the over-all energy efficiency.
It will be shown that load adaptability of these efficient and flexible drive systems~makes it easy to create ttze schematic conditions under which the energy accumulated during decelerating the motor vehicle is reused for accelerating the vehicle.
1t is understood that availability of ttte motor position input-command signal Xo~ makes it possible not only to regu.lat.e l.tu.~. C t.uic3 motor posi t.iort X.l , taut ~3lso to control l:lte fluid motor velocity. It is now assumed, for simplicity, that motor vehicle is moving only in a horizontal direction. Accoding.ly, it is also assumed that five-way spool valve 2 is working now as a one-directional valve - it's spool can be moved only down from the nPUt:ral spool position and can be returned back to the neutral spool position only (which is shown on figures lU and 11).
Note that vigures lU and 11 are used only for a further study of .i.oad adapt; ive regeneration of energy . The related veloci t.y feedbactc control (Fig. l6) and especially the related open-loop control (figures 17 to 22, and 26) are,~of course, more likely to be u:~ed for the motor vehicle type applications.
In general, the load adaptive, position feedback controlled;
variable speed drive systems may incorporate a huilt-in regenerating circuitry or an independent regenerating circuitry.
The drive system incorporating the built-in regenerating circuitry is shown on Fig.lO which is originated by combining t~ig.b and Fig.2. However, the fluid power supply of Fig.2 is represented on Fig.lO mainly by pump 58. The regulator 3-3 is not needed now and, therefore, is not shown on Fig.iU.
On the other hand, the regulator 3-4 is replaced by a variable displacement color 66 having a variable diaplaceaent means 6e , ~ar.K
line 74, and pressure line 78 which is connected to line L,.
The hydraulic cylinder 1 ~Aawn on Tis.6 !a r~plaa~d by the rotational hydraulic rotor 1 ~hioh ii loaded by a load 96 r~pr~a~ntin~r-i~iass of the actor vehicle.
The tly~rhaal 9~ is attached to the ooaaon shaft ~2 connecting pump 58, sotor 6fi,and the priaary actor 10o of the motor ~rahicla. The rariabla displaeeaent means 68 is modulated by the a~chaust line pressure d ~ feedback signal, which is equal PD - P~ and is aaasu~~linn L5 (through line ~6) and the rilated sisna.l line 'Ls. The exhaust line pr~ssur~ drop t~~dba~t control systea inoludin~r the ~ariadl~ displaeeaent motor 66 , r~~ulatas the ~~chau~t fluid pr~~~ur~ drop PpS-..Ps aero~a spool valve 2 by prying the oountarproaaura P~ ~ pOs -- Ots in the uchaust Dower line Ls by the variable displaaeaent means 68. to a aiapla case, cne aotor~position eoe~eand si8nal Xo bain~ pried with the constant speed, will yananta a ralaxiraly constant ralocity o t actor 1 and the positional lad rO,X proportional to this ~~loeity. In ~~n~ra'l, the shaft ~~looity of rotor 1 can be oontroiled by the sped of raryin~t the actor position command sisnsl xc. Durin; the dieeleration of the motor vehicle, the kinetic energy aeeueulated by~a mss=
of the motor vehicle (load 96) is transmitted throu~rlt motor 66 to the t:y~.wh~~l 94.
Durins the tollowin~
aecelention of the motor vehicle, the kinetic enerar accumulated by fl~..whssi 94 is transsitted back through pump s~! to the motor vehicle. The exchange of kinetic ~n~rtY between the motor vehicle (load 96) and the flywheel 94 is correlated with the tl~whssl speed fluctuations.
It is assumed that a aped-torque characteriatia of the primary motor 100 t such as the electrical motor or the ~ternal-combustion engina~ is soft enough to allow these fl~~heel speed fluctuations.

WO 99/64761 3~ PCTNS98/12200 -The load adaptive, position feedback controlled, variable speed drive system having an independent regenerating circuitry is shown on Pig.ll, which can be considered as the further development ( or modification ) of Pig.lO.
In this drive system, a variable speed primary motor 92 of the motor vehicle is not connected to shaft ?2-the ~r~~i~mar,~,r but is drivin~r~.~-shaft 98 of a variable displacemenfYpump 9G.
The tank line 38 of pump 90 is oonneoted to tank 62.
The pressure line 54 of pump 90 is connected through check valve 40 to the supply power line L2.
The variable speed primary motor 92, the related speed control circuitry which is meant to be i.nc3.uded into block 92, and thi r riable displacemep 90 are all included into ~upply line pressure drop feedback control syetes.. The variable speed primary rotor 92 i~ sodulated by ~~ly line pressure drop feedbaclt signal PZ - p02 ' which is measuredrbmtrreen line 54 (line 91) and line 512.
As a result, t 'eu ty line pressure drop leedbact ~rim~rv control system is capable of maintaining the~'eupply fluid ressrre drop P2 - P02 across spool valve 2 by varying the pressure rate '2= p02 "'~ ~p2 in the supply power line 54 by varying the speed of the variable speed primary motor 92, such as the internal-combua'~ion engine or the electrical motor.
On the other hand, the pump 58, shown on Pig.lU is replaced on pig,ll by an assisting variable displacemen~ pump 55 having an assisting variable diaplaaement~ means'S7 to make up an assisting supply line pressure drop Iet system. The line 36 of pump 55 is connected to tank 62.
The pressure line 30 of pump S~.is connected through check valve 44 to line i~2. The, assisting , variable displacement means 57 is eodulated by an assisting supply line pressure drop feedback signal p~ -- POZ , which is mea~~~i line 30 ( through line 32 ) and line SL2. As a result, the assisting supply line pressure drop feedback control eystes is capable of maintaining the assisting supply fluid pressure drop P2R..... p~2 aoroaa spool valve 2 by varyir>ir the assisting preasur~ rate PZR.... P02 ,-~-. Ap2R
in the supply power line 30. DurinE the operation, !he supply power line LZ i~ switched oust to line ~ or line 30, whichever has the higher pa !s ~s~ n rats' by the losie of check valve! 40 and 44, , ~ pressure drop comauand si ~,~,PZR is selected to be dust slightly larger th~nG~pressure drop command signal ~ PZ . Accordingly, whSl~ the speed of tlyLwheel 94 is still+~e~lati,vely high, tlc~"crs P=R~ PaZ t OPZR will express a P2 - P02 "i" 0 p2 and, hence. the supply power Iin~ L2 will be connec~.ed to line 30 through cheek valve 4~. At arty other time, the supply power line LZ
is connected to line ~ through. chealc valve 4a, In other words, the independent regenerating.aiseuitry, including rotor 66, pumg ss, sr~d tl,~rrheel g4, is liven a.priority in supplying the fluid energy to the supply power line L2. This independent regenerating circuitry is autoartically entering into,. and is automatically withdrswing trop the regulation of ie s y fluid y~rsssurs drop across spool valve Z. The ~sohang~ of Idnetio energy betwreen the motor vehicle (load 96) and the tly~rhsel 94 i~ basically aaeosplished as eonsidesed above (tot the saheaatia shown on P1~.10)f however. the undssirsbl~ interference bet~rsen the primary motor 92, such as the electrical motor or the internal-combustion engine, and the regenerating circuitry is rtow eliminated. .
It should be noted that the variable delivery means g3 of pump 90 can be employed.for achieving some additional control objectives, such as maximizing the energy efficiency of the internal-combustion engine 92.
In fact, these additional control objectives can be similar :to those Nhich are usually persuaded in regulating the standart automotive transmissions of motor vehicles.
It should also be noted that schematic shown on Fig.ll is of a very general nature and can be further modified and (or) simplified. If there is no additional control objectives, such as dust indicated, the variable speed primary motor 92 is replaced by a reldtively constant speed primary motor 100, while the variable deliver means 9~o~'~f'mP ~0 is employed fvr maintaining pressure- Y2 ~ p02 -~ ~p2 in line 54.
This case is Illustrated by Pig. l2 which is a modification of Fig.ll for the hydraulic press type application.
In this case, the rotational hydraulic motor 1 is replaced by the double-acting cylinder 1. The exhaust line pressure drop feedback control system including motor 66 is adapted to maintain pressure P3 = P03 -- ~ P3 in the exhaust power line L3~
The potential energy of the hydraulic fluid compressed in chamber 10 of cylinder 1 is regenerated now by the independent regenerating circuitry through the exhaust power line L3 and the related exhaust line pressure drop feedback control system !n:iudi~g rotor 56. ~n fact, the schsmati'c of Fia.l2 __ easily understood ,just by comparison with Pig.ll and Fig. g.
rcor sia~pl'city, the additional fluid power supply 50 is rot ,gh~n on Fig. l2.
Rome preliminary generalization.
'Phe motor load and the motor load means are ~ the structural components of any energy regeneratingptive fluid motor control system. For this reason, Fig. l2 ~as wel_7_ as Fig.9 ) also shows 'the Frame 190 ( of a hydraulic press 7.9?. )~ against wliicti the chamber; 10 of cylinder 1 is loaded. The compressed :~luid energy is basically stored within chamber 10 of cylinder 1; however, the stretching of frame 7.90 of press 192 may substantially contribute to the c~.lcula-tions~of the over-all press energy accumulated under tile load.

It is noted that word "LOAD" within block 96 (see figures i0, 11, 16 to 22, and 26) is also considered to be related a substitute for the words "'the motor load means"and i all -the possible aPPlica.tions of this invention.
1.n a case of motor vehicle applications, the motor load means include a mass of a' "~whoc~led" motor vehicle (as .ia is specificaJ.ly, indicated. on the schematic of rig.22,, Tn the energy regenerating, load adaptive .fluid motor control sys~terr~, such as shown on figures 9 to 12, it is often justified to consider the fluid motor and load means_as an ini;egrwted component. The fluid motor and load means include 'the fluid motor means arinotbr load means and accumulate a load related energy, such as a kinetic energy of a load mass or a compressed fluid energy of -the fluid nde st od as motor-cylinder. The "exitiaust fluid energy" is~~'~"f the load related energy being ~tr.'ansmit~ted 'through the exhaust power line (that is line L3 or line L5). T he "exhaust fluid energy" can also be referred to as the "waste fluid energy: that is the energy which would be wasted unless regenerated.
There are basically 'two types of counterpressure varying means:
a) the counterpressure varying means which are not equipped for recupturing the load related energy ( such°as~~the exhaust line pressure drop regulator -- see figures 1, tH, ~ and 6 ) , and b) 'the counterpressure varying means which are equipped .for re cupturing -the load related energy ( such as 'the exhaust line variable displacement motor - see figures 9~ 10, 11, ..
and 12). This counterpres~sure varying and energy recupturing means can also be referred t o as the exhaust line energy recupturing means.
S t,i ll other modifications of 'the exhaust line e~nergy'~
recu~auring means will be considered later.

~vrooci3.ngl.y, 'there ara basically 'two 'types of 'the load adalrt:i.ve :flu.i.d motor coni;rol. systems t , a.) /;Ire ~Lc~ncl aclapta.ve fluid motor corrtrol sysl:ems which are rroi; ~qua.pped .Cor, uegenera~ti.ng l:he l.oa.d related energy ( gee.
:f i.gt.rres 1. , ~I , and 6 ) , a.nd Ir) ~t:lre l.o;rd ~dapl:ive fl.u:i.cl moU:or c~orntro7. sy:3l;erns havi.rrg awencrgy- regenerating circuitry for regenerating 'the J.oad r. el.al;~d energy ( see .figures 9 to 7.2. ) . Z~his second type of load a.daptj.ve .fl.u~.d motor control systems can also be referred ~I:v a.s 'the regenerative aclaptive f7.txid motor ' conl;.rol. qysl:ems. SaiJ.l. other rnodi:Cications of the r.egeme.rwti.ve adap'tive'~fl.uid mo'l;o.r control systems will. be con s i.dered lager.
:I'I; should be r~rcoted that regenerative adaptive fluid motor cowl;.rvl schematics being considered are the concept illustrating schematics only and, therefore, are basically free from the detai_1_s, which are more relevent to the engineering development of theQe concepts for specific applications. For example, the maximum ~rtd minimum pressures in hydraulic power lines must be restricted. Someidesign related considerations are summ~ri~ed :rt i;he end of this .description.
General criterion of dynamic stability of combined com,~nen't syst ems_ '/'toe .l.oac .-,dapt:ive fluid motor pos.it.i.on feedbaclc control :system ~ontro~
.i ~: typic311y a combination oI at lead; Lhrse component fe syst.Earn;~ - l:he f.l.u:id motor po:3ition feedbac)c control system, at least one exhaust .lane pres3ure drop feedback control systern, rrnd at ).east one supply line pressure drop feedback control r:y::t:em. In order to prevent a possibJ.e s~r~6a~#a~- cVI»~O~ex' .inl:er.ference between tire comb] ned components systems, the preasuro drop feedback contro.t systems roust be properly regu laced t~ol:h w.i.t.lr respect to the Iluid motor position feedbac)c contuul.

system and with respect to each other.
Accordingly, a general criterion of~dynamic stability of cmbined component systems (which are stable while separated) can be intrud~rced by a set oi~ pc~ovisions (of by a combination of concepts) as Col.lows:
(1) preventing~a substantial schematic.operation~~interference between the pressure drop feedback control systems and the fluid motor position feedback control system ( this concept has been already discussed before);
(7) providing a significant dynamic performance superiority for flee pre:~sure c9rop i~eedback control systems against the fluid motor position feedback control system, in order to prevent ' substantial c9ynamic operation interference between the pressure drop feedback control systems and the fluid motor position feedbaclc control system (this concept will be discussed later);
(:7) preventing a substantial..pressure drop regulation interference between the supphy and exhaust line pressure drop feedt~ack con trol systems - thi3 concept is discussed below.
'fhe concept of preventinct a substantial pressure- d roy regulation interference.
I t si2ould be noted that; pressure-compensated flow characteristics which are shown on figures .3-B. 5-B. and 7-D, can generally be reduced to each of two asymptotic characteristics as follows s a motor static sped characteri~~tic . describins the hydraulic motor speed veraus~.ths valve spool dir~l~cementi under thi~~as~umpticn that the hydraulic rluid is not compressible ~
(b) a compression - d~compreaaion sped v~r~ua the valve spool displacement~,ursd~r the assumption that the hydraulic motor speed is equal to zero.
As a result,~the speed control of fluid motor.l by any pressurs~. drop feedback control system is generally efTeci ed by the processes of compression-decompression of hydraulic fluid and, therefore, is substantially inaccurate. This speed control is, of course, still further effected by some other factors, such as the ;;tatic~and dynamic errows in maintaining the pressure drop.
It is also understood that a simultaneous speed r control of fluid motor 1 by the supply and exhaust line pressure drop feedback control systems may cret~te ~ ressure'~
drop regulation interference between these two systems. This pressure drop regulation interference may reveal itself in generating excessive pres~ur~ wave , producing hydraulic shocks, cavitating the hydraulic f7.uid, and accumulating an air in the hydraulic tracts.
Moreover, the pressure drop regulation interference may lead io the over-all dynamic instability of the load adaptive fluid motor control system, such as the regenerative adaptive fluid motor control system.
The destructive conditions of pressure drop regulation interference can be avoided simply by preventing a~simultaneous speed control of fluid motor 1 by two pressure drop feedback control systems, that is by the supply and exhaust line pressure drop feedback control systems. 'vVith out the loss of generality , the concept of preventing a pressure drop regulation interference is considered further more specifically for 'two examplified groops of schematics as follows (a) the load adaptive schematics tneving only one loadable chamber and, therefore, having only one pressure drop feedback control system controlling the speed o°f motor 1 at any given time - see figures 1, 4, 9, and 12;
(b) the load adaptive schematics having two Ioadable chambers, and therefore, having two pressure drop feedback control systems which potentially may participate simultaneously in controlling the speed of motor- J. - aee f figures 11 and 16 to 22 .

In the first groop of load adaptive schematics, the supply and exhaust line pressure drop feedback control systems will obviously never interfere. In these schematics, the speed of motor 1 is usually controlled only by a supply line pressure drop feedback control system ( that is by the primary supply line pressure drop feedback control system or by the a:~sist.ing supply line pressure drop feedback control system ).
The motor-cylinder 1 having only one loadable chamber is assumed to be loaded in only one direction by a static force.
Accordingly, the motor load is measured by the pr'essur'e signals P~2 = PQ3. Tlie exhaust line pressure drop. feedback control system is usually ire operation only during the decompression of chamber lU ut~ motor L.
In the second groop of load adaptive schematics, a simultaneous speed control of motor 1 by the supply and exhaust line pressure drop feedback control systems is prevented by controlling the sequence of operation of these systems by the motor load of of motor 1, provided that pressure C1TU~ cumrnand signals ~ >-y , Q PlR ~ and ,dP5 are selected so that aP5 ~~P2R ~~l'2 .
Let's consider now more specitic:ally t.l:e second group of load adaptive schematics. 1'lie mr3gnitude and di.rect.ion of the motor load is conveniently measured by. the pressure signals E'p1 and PAS.. which are implemented :fur controlling the supply' ~nnd exhaust line pressure drop leedbacJc control systems, c~espec~tively. The load pressure signals E'p~ a~~d l'p5 are also used for controlling the ~:eyuence of operation of these pre:aure drop feedback control systems, as it is illustrated below.
Let's assume that wheeled vehicle is tested in a horizontal direction only. And let's consider br.iehly the related stop-and-go energy regeneral:ing circ;lE~~ ( wh.ich i:v ::t..i I 1 P,~r~ t»r studied later - see Hig.25 ).
1. The wheeled vehicle is moving with a coostr~nt speed.
In this case, the motor load is positive, tt~e load pressure signal P02 is relatively large, end the prirnary supply line pressure drop feedback control system is activated to mairiLain the primary supply fluid pressure drop Y2 ~t'02 - a P2 across spool valve 2. Un ttre utirer land, the pressure signal P05 is very smal.I, and therefore, the exhaust line pressure drop feedback control system is not activated to maintain the exioaust f laid pressure drop P05 - r5 = ~t'S acr-U~ss bpool vat ve ~ .
Note that in this r.HSe, the exhaust; fluid pressure drop P05 - P5 is ~yual approximately to the prirnary supply line pressure drop command signal ,p E~2 , provided f.hat supply and exhaust openings of valve 2 are identical. Note also Lhat i f P5 ~= 0 : P05 =,~, p2 ~
2 . The Wheeled vehicle i.s cltcelerated .
In this case, the motor load is negative, the load pressure signal P05 is large, and the exhaust line pressure drop feedback control system is activated to maitain the exhaust fluid pressure drop P05 - P5 =,p p5 across spool valve 2. Un the other hand, the pressure P02 is very small and has a tendency of dropping "below zero". In practical applications, a vacuum in motor line L1 must be prevented by introducing ~ check valve (such as check valve 155 on figures 20 and 22) connecting .l.i.ne L1 with the oil tank 62 ( or with a low-pressure hydraulic accumulator). Note that by virtue of expression (3), the process of deceleration should be started onle after this check valve is open. It .is understood that in this setuation, the supply line pressure drop feedback control systems have no effect on the process of deceleration of. motor 1.
3. The wheeled vehicle la completely stopped.
In this case, the fluid motor 1 is not regulated.
4. The wheeled vehicle is accelerated.
In this case, the motor load is positive, the load pressure signal P02 is large, and the assisting supply line pressure drop feedback control system is activated to maintain the assisting supply fluid pressure drop P2R"" PU2 = D PZR across 'spool valve 2. On the other hand, the pressure signal P05 is very small, and therefore, the exhaust line pressure drop feedback coni:rol system is not activated to maintain the exhaust fluid pressure drop Pp5 P5 " p P5 across spool valve 2. Note that in this case, the exhaust .fluid pressure drop P05 - P5 is equal approximately tv the assisting supply line pressure drop command signal, P2R, provided that supply and exhaust openings of valve 2 are identical. Note also that if P5 = 0 . P05=~,OP2R~~' P5 Finally, it can be concluded that in the load adaptive fluid motor control systems, the functions of th a motor load are not limited to controlling separately each of the pressure drop feedback control systems. ~ Indeed, the functions of the motor load are generally extended to include also the control over 'the sequence of operation of the supply and exhaust line pressure drop feedback control systems , iri order to prevent a possible pressure drop regulation interference between these pressure drop feedback control systems.
The concept of providing a significant dynamic performance superiority.
is ir~porrart :o st: sss that the concept of providi~g 3 aignifican'. dynamic performance superiority for the orsssure drop :'3edback control systems against the fluid "~~r position f$edback control system is an integral dart,:' ~.~;! s i.~.ven: i ~.~.. This concept introduces a cr; terior.
f ~ynamic s tabiiity of combined camponent systems ~Hhic'.~.
are stable while separated (provided that the concept of WO 99/64761 4o PCTNS98/12200 -preventing a schematic operation interference and the concept of preventing a pressure drop regulation interference are already properJ.y implemented). As it is already mentioned above, the load adaptive fluid motor position feedback control system is typically a combination of at least three component feedback control systems - ~tti~ fluid motor position feedback control system, at least one exhaus:
line pressure drop feedback control system, and at least ins supply line pressure drop feedback control system.
The theory and design of the separate cloned=loop systems 3=s described in numerous prior art publications - see, for example, the books already named above, and also r a) Shinners S. M., "Modern Control System Theory and Application", Second Edition. -Reading, 1lassachusetts s Addis.on-Wesley Publishing Compat~y, 1972, b) Davis S. A., "Feedback and Control System".
New York a cimon and Shunter, 1g~4.
It is further assumed that each of the separate component systems is_ linearized and, thereby, is basically described by the ordinary linear differential equations with constant coefficients, as it is usually done in the engineering calculations of eleotrohydraulio, hydromech~nical, and hydraulic closed-loop systems. Note that the fluid motor position feedback control system (separated from other component systems) is especially easy to lineariaed if to admit that the expected regulation of the exhaust and supply fluid pressure.drops is already "in place".
Let's consider (without the lose of generality) the load adaptive fluid motor position feedback ~ontrol.system incorporating only three component systems - the fluid motor position feedback control system, only one exhaust line pressure drop feedback control system, and only one supply line pressure drop feedback control~system. In this case, the criterion of dynamic stability of combined component systems can be reduced to only five conditions as fellows .

(i) providing a 3yr.amic stability of the fluid mot;.r position feedback control s;~stam ;
(2) providing a dynamic stability of the exhaust lire or~ssure drop feedback control system ;
3) providing a dynamic stability of the supply line press ure drop fead~back control system ;
(u) preventing a substantial dynamic opera'. ion inTerfers.~.ce between the exhaust :lui3 pressure drop regulation and the motor position rsgulati:.n by. providing a significant d;~na:~_c perfoirmance superiority,for the exhaust line pressure drop Feedback control system against the fluid motor position feedback control system ;
(~) preventing a substantial dynamic operation interference between the supply fluid pressure drop regulation and the motor position regulation by providing a significant dynamic performance superiority for the supply line pressure drop feedback control system against the fluid motor position feedback control system.
The presented above- first, second, and third.conditions of dynamic stability are the requirements to the separate component systems. The fourth and fifth conditions of dynamic stability define limitations which must be imposed on the separate component systems in order to combine them t:~~gether. The design of the separate closed-loop systems for the dynamic stability and required performance is well known in the art, as already emphasized above. For this reason, it is further assumed, for simplicity, that the first three conditions of dynamic stability are always satisfied if the last two~conditions of dynamic stability are satisfied.
Because the last two conditions of dynamic stability are similar, they can also be specified by a general form as follows .
preventing a substantial dynamic operation interference between the pressure drop regulation ( the exhaust or suppl:/

fluid pressure drop regulation) ahd the motor position r.gulation by providing a significant dynamic performance superiority far the pressure drop feedback control system ( :he exhaust or supply line pressure drop ieedbaek control system, r~spectively ) against the motor position feedback control system.
The provision of preventing "a substantial dynamic operation interference" is associated with the concept of providing "a significant dynamic performance superiority". The term "a substantial dynamic operation interference" is introduced to characterize the dynamic instability of combined component systems which are stable while separated. This dynamic ' in4~cability can be deteoted in a frequency domain or in a time domain by #td = 1 .. .
Rp or by ~ ~rp = 1, ~5) tfd ' respectively, where i (~Rp and ttp are~the resonant frequency and the final transient time (respectively) of the fluid motor position feedback control . system a ' wRd '~ pfd are the resonant frequency and the final transient time (reapeotivelyj of the pressure drop feedback control system.
The closed-loop resonant frequency ~R ( that is ~Rp or ~Rd ) is located by a resonant peak of the closed-loop frequenoy-reaponae:eharaeteristio and, therefore, is also often called "a peaking frsquenoy".
This resonant peak is typically observed on a plot of the amplitude portion of the closed-loop frequency-response characteristic. However, the resonant peek is observed. only if the system is underdQmped.
For this reason and for simplicity, the appropriate approximations of the ratio ~ can also be ''"'Rp employed. For example, the possible approximation is ~Rd ~= ~d -" ~ (6) -"RP ~p where ~ ~ and ~ ars the closed-loop bandwi3ths bP bd for th~s position faedback control system and '!:s pressure drop feedback control system, respectively.
,, Moreover, as the first approach (roughly approximately) t C(~d ,~ ~ cd ,._ ' ( ? ) wRp ~ocp where p and ~cd are the open-loop cross-oust lrsqusnaise for the positidn te~dback control system and the prsesurs drop tssdbaak control system , rsspeotivsly.
1'!to final transios~t tlao Et t that is t~ os t~ ) of :~:
oloasd~looD ayslw 3s tho total outDut~roa~on~s tiu to :ns step input. The transient time~t~, is also often called "a settlir~ time" and is measured between t - 0 and ~ _-.. tf - when the response is almost completed.
T.he method of defining the closed-loop resonant frequency the closed-loop bandwidth ((Jb , the open-loop cross-over frequency and the closed-loop f'_nal transient time tf are well known in the art - see, for example,the above named books of S. M. Skinners , S. A. Davis . and A.F. D'Souza .
In accordance with equations (4) and (5),there are two interrelated but still different aspects of dynamic instability of combined component systems which are stable while separated. Indeed,the.equation (4) symbolizes a frequency resonance type phenomenon between the component systems. ~ On the other hand, the equation represents a phenomenon which can be viewed as an operational break-down of the combined component ,systems. Note that the exhaust and suppl;~ 1i.~.e pressure drop feedback control systems are the add-vn futures and may fullill their destination within the load adaptive fluid motor position feedback control system only i:
the destructive impacts of "a substantial dynamic operation interference" are prevented by "a significant dynamic performance superiority"
Now, it is understood that if "a substantial dynamic operation.
interference" is identified by (4) or (5), then "a significant dynamic performance superiority" should be identified by a ~d ~ Sc~r ( a ) '~' Rp and tfp ~ St .
- t td ~rhere s ,. ,S'w is the minimum stability margin in a frequency domain, ~, is the minimum stability margin '_n a time domain.
These minimum allowable stability margins can oe specified approximately as s "sue = LO and s~ ~' 10.
The formulas (8) and (g) must bs introduced into the design of tho load adaptive fluid motor position feedback control system. The way to do this is to design tie separate component systems for the dynamic stability and required performance while the inequalities (9) and (9) for the combined component systems are satisfied.
The approximate connections between the resonant frequencies a~.d some other -typical frequencies have been already illustrated by equations (6) and (?).
'~Ihile the equations (8) and (g) are valid for the second -and higher- order di!lerential equations, the principal relationship between the final transient time 't~, and the resonant freouency (~R is more easy to illustrate for the second-order equation .
A~ z c~ 2 .
.~ __ df which can be modified as s c~12 d z . .
-~- 2 ~ u~
----- -i- GlJ2 .Z' -- GlJ .y and ~Z ~ 2 ~- -~-z~ s, d~ ~2"

where ~ y and Z are the input and output, respectively:
the undamped natural frequency /.t~2 - ~2 ' ~he damping coefficient -- ~~ ~
y' 2 w~
the dimensianless time For this second-order equation, the output responses .2 ~2"~
to a unit step input ( whi.La the initial conditions are zero) for various values of are well known in the art - see,lor example, the above named books of 5. M. Skinners and 8. A. Davis.
Note that for the second-order equation ~:=--~-- and, hence, ~2 the final~transient time tr Tha final transient ':
dimensionless time ~ is a funotion of the damping coef-fioient ~. More generally' when the right part of the second - order equation is more complicated, the final transient dimensionlese time ~ is also e!leoted by the right part o! thin equation.
In the ease of using seoond-order systems, the ratio ~Rd can be approximated by the ratio ~Rp , ~ ~z p and therefore tf p - ~Rd ~f ~2d ~f P ~ ----.~-. , pfd ~2p ~fd ~~Rp ~fd where r (,J2p and ~rp are the undraped natural frequency and the final...transient dimensionless~~~time, respectively, for the WO 99/64761 4~ PCT/US98/12200 -position feedback control system =
~2d and ~fd are the undbmped natural frequenc;r and and the final transient di:~ensionless time, respectively, for she pressure drop feedback control system.
In general, for, the second - and higher -order systems, it can be still stated,, by~the analogy with the second-t order system, that the ratio -~ .is basically dependent ~Il- fd on the ratio ~~~~d and is further dependent on the wR P , secondary factor~.such as the effeots of damping.
It, is to say that expression (8) can bs viewed as a basic (or main) test on the dynamic stability of combined components systems which are stable while separated.
This main test is needed to prevent the frequency resonance type phenomenon between the component systems.
However, an additional test - equation (9) is still needed to prevent the operational break-down of the combined component systems.
In short, for the second- and higher-order systems s a) the expression (8) - alone is a necessary criterion for the dynamiv stability of combined component ty3tems which Are stable while separated i b) the expressions (8) and (9) - together are a su1'fieient criterion for the dynamic stability of combined component systems which are stable while separated .
Of course, still other terms, interpretations, and measure-ments can be generally found to further charact~e~),ze what have been ,)ust clearly defined - based on the physical considerations - as being "a substantial dynamic operation interference" and "a significant dynamic performance . - superiority.

WO 99/64761 4g PCT/US98/12200 -Adaptive fluid position feedback control:
the scope of expected applications.
The load adaptive fluid position servomechanisms make it possible to substantially improve the energy, performance, and environmental characteristics of the position feedback control in comparison with the conventional fluid position servomechanisms.
In particular, the load adaptive fluid position servomechanisms may combine the high energy-efficient and quiet operation with the relatively high speed and accuracy of performance.
1'he artificial load adaptability of load adaptive fluid position servomechanisms is achieved by regulating the exhaust and supply fluid pressure drops by the exhaust and supply line pressure drop feedback control systems, respectively.
because the artificial load adaptability is implemented by relatively simple design means, the load adaptive fluid position servomechanisms combine the very best qualities of the conventional !'=uid o~otor position teedback control systems and the naturally load adaptive, electric motor position feedbaelc control systems. Moreover, the load adaptive fluid position servomechanisms may incorporate the energy regenerating circuitry.
Furthermore, maintaining the exhaust and supply fluid pressure drops across the dirsctional control valve may protect the position closed-loop against such destructive conditions as generating excessive pressure waves, producing hydraulic shocks, cavitating the hydraulic fluid, and accumulating an air in the hydraulic tracts.
In other ~~ords, the transition to the adaptive servomechanisms makes it easy to control the fluid conditions in the hydraulic tracts and to provide a' ~~fuli hermetization"
of the hydraulic motor.
Accordingly, the.scope of potential applications of the adaptive hydraulic position serromechanisms~ being considered is a:tsemely wide. so, it is expected that the conventional hydraulic ( eheotrohydraulic or hydrom~chanical) position ~~rvom~chanisms will b~ replaced almost w~rywh~r~
by the load adaptive hydraulic position servomechanisms.
It is .~lsc exp~ct~d that maxty naturslly load adaptive, eleotric motor position feedbaeft control systems will also be r~plao~d.by the artificially load adaptive, hydraulic ootor position feedback control~s~yst~ms.
In addition. it is expected that marry electrohydraulie, hydromechanical,and electromechanical open-loop position control systems will also ~ba replaced by thi load adaptive ~ .
electrohydraulic and hydromechanical position servomechanisms.
The load adaptive fluid motor position feedbacic control Systems can be used in machine tools (including presses), construction machinery,'agricultural machinery, robots, land motor vehicles, ships, aircrafts, and so on.
In general, the load adaptive fluid position servomechanism can be viewed as a combination of a primary motor, such as the electrical motor or the combustion engine, and the load adaptive, position.feedback controlled fluid power transmission, transmitting the mechanical power from a shaft of the primary motor to the load.
The fundamental structural improvement of the position feedback controlled fluid power transmissions, as described in this invention, makes it possible to substantially increase the scope and the scale of their ,justifiable applications.
w ror example, the scl~ernatics shown on figures 9 and 12 can be used for constructing the high energy-efficient hydraulic presses. 'Phe load adaptive hydraulic press may have advantages against the conventional hydraulic and mechanical presses due o a combination of factors as .follows:
1. These rgy-efficiency of the hydraulic system combining the load adaptive primary power supply and the load adaptive WO 99/64761 5~ PCT/US98/12200 -regeneration of energy.
2. Superior performance and environmental characteristics including: the smooth and quiet operation of the moving slide, the smooth compression and decompression of 1. the hydraulic fluid, the high speed, accuracy, and dynamic performance potentials.
3. The press is easy to control with respect to the moving slide position, stroke, speed, and acceleration. The press maximum tonage is also easy to restrict for the die-tool protection.
4. Simplicity of design - only one regenerative adaptive hydraulic position servomechanism is required to provide all the benefits described.
Finally, it should be noted that~schematics shown on figures 4 and 12, make it possible to absorb the shocks generated by a sudden disappearance of load, for example, during the punching operations on hydraulic presses. This is accom-plished by decelerating the motor-cylinder 1 just before the load diaappear~ to provide the valve spool to be clone to its neutral point ( ,~ X ~ 0 ) . ~ Just after the load disappears, the position feedback control system lock' the fluid in chamber 11 or even connects this fluid with the supply power line I2. It means that the potential energy of the fluid compressed in chamber 10, is used mostly to compre~~ the fluid in chamber 11 and, finally, is converted to a heat. ' Adaptive fluid motor feedback control Fig. l3 shows a generalized model of the load adaptive fluid motor output feedback control systems which include an independent energy regenerating circuitry. This rnodeJ.
ca.n be viewed as a further development of I~'ig.8 in view of figures 11 and 12 and is must ly self-explanatory.
Note ths~t. the position feedoHCk control means ( block lE ) and tile related signals Xl, Xo, and p X , which are shown on Fig.a,~~are replaced by 'the ( motor ) output feedback control means ( block 4-M ) a.nd i;he related signals Ml, Mo, dnd pM, which are shown on Fig. l3.
More speoifically, the motor position X1 , the position input-command signal Xo, and the position feedback control error signal /~X are replaced by their "generic equivalents" - the motor output M1' the related input-command - signal Mo , and tho motor output feedback control error signal Q M, respectively.
Hy the analogy with the load adaptive fluid motor position feedback control system, the motor output feedback control error signal O M is produced by the output feedback control means (block ~~-M) in accordance w~,th a difference between the input-command signal Mo and the motor output M1 , Clearly,~the motor output is a generic name at least for the motor position, the motor velocity, and the motor acceleration. Accordingly, the load adaptive fluid motor output feedback control system is a generic name at least for the following systems a) .the load adaptive fluid motor position feedback control system:
b) the load adaptive fluid motor volocity feedback control system=
c) the load adaptive fluid motor acceleration feedback control system. , The general criterion of dynamic stability of combined component systems, which was formulated above with respect to the load adaptive fluid motor position feedback control system, is also applicable to the load adaptive fluid motor output WO 99/64761 52 PCfNS98/12200 -feedback control system. In particular, the concept of providing "a significant dynamic performance superiority", which formulated above with respect to the load adaptive fluid motor position feedback control system, is also applicable to the load adaptive fluid motor output feedback control system.
rye e-~nerative A generalized model of the adaptive fluid velocity servomechanisms is shown on Fig. l4. This model is derived from the one shown on Fig.l3 just by replacing the (motor) output feedback control means (block 4-~I ) and the related signals Ml, Mo, and OM ~ by the velocity feedback control means ( block 4-V ) and the related signals V1, Vo, and QV, re~,pectively. It is to say that the schematics for the adaptive fluid velocity servomechanisms being considered can also be derived from the above presented schematics for the adaptive fluid position servomechanisms just by replacing the position feedback control means (block 4 ) and the related signals Xl. Xo , and O X by the velocity feedback control means (block 4-V ) and the related signal Y1, Vp, and O Y, respectively.
The motor velocity V1 is the velocity of the moving part 21 of the fluid motor 1. In fact, the motor velocity V1 can also be viewed as a mechanical signal - the output velocity signal of the load adaptive fluid~motor velocity feedback control system. The motor velocity Vl is measured by .
the velocity sensor, which is included into block 4-V and is connected to the moving part 21 of the fluid motor. 1. ~ The velocity feedback control error signal QV
is produced by the velocity feedback control means (block 4-V) in accordance with a difference between the velocity input-command signal Vo and the motor velocity V1.
It is reminded that at the balance of the position feedback controls Q X = 0 and the spool of valve 2 is in the neutral spool~position for any given value of the position command signal Xo. Accordingly, at the balance of the velocity feedback control: dV = O= however, the spool of valve 2 is not generally in the neutral spool position but is in the position which corresponds to the given value of the velocity command signal Vo. It is already understood that the velocity feedback control means (block 4-V ) can be still further described basically by~the analogy with the above brief description of the position feedback control means (block << )~ The optional physical structure of the ~relocity feedback control means ( block 4-V ) is also disclosed ' by numerous prior art patents and publications describing the conventional fluid motor velocity feedback control systems and the related velocity feedback control technique - see, for example the books already nsmed above.
The schematic shown on Fig.l6 can be used for constructing the load adaptive , velocity feedback controlled fluid power drive systems for the motor vehicles. This schematic,is derived from the one shown on Fig.ll by replacing the position feedback control means (blocx 4; and the related signals Xo, X1, and OX by the velocity feedback control-means (block 4-V) and the related ~i=.nals Vo, Vl, and ~Y, respectively.
In addition and for simplicity, the five-way spool valve 2 shown on Fig.ll is replaced by the four-way spool valve 2 shown on Fig. l6. Accordincly, the supply power line L6 and the exhaust power line L~ are eliminated.
Phe four-way spool valve 2 is considered now to be a one-s pool directional valve- it's"L'dPf'be moved only down from the neutral spool position and can be returned back to the neutra~
spool position only ( which is shown on Fig.l6 ).

Regenerative adaptive fluid motor control.
A generalized model of the regenerative adaptive fluid motor open-loop control systems is presented by Fig. l5 which is derived from Fig.l~ ,just by eliminating the output feedback control means (block 4-M ) and the rel;~ted signals Mo , M1 , and OM . The schematics for.the load adaptive fluid motor ~~open-loop control systems can be derived from the above presented schematics for the load adaptive fluid motor position feedback control systems gust by eliminating the position feedback control means ( block 4 ) and the related ai~rnal Xo~ X1, and QX.
The open-loop schematic, which is shown on~Fig.l7 , is defived from the one shown on Fig. l6 ,just by eliminating the velocity feedback control means ( block 4-V ) and the related signals Vo, Vl, and LAY.
The schematic of Fig. l7 can be used for constructing the high energy-efficient load adaptive motor vehicles, as it will be still further discussed later.
The general criterion of dynamic stability of combined component systems, which was formulated above with respect to the load adaptive fluid motor position feedback con trol systems, is also applicable to the load adaptive fluid motor open-loop control systems. In particular, the concept of providing~~~d bignificant dynamic performance superiority", which is formulated above with respect to the load adaptive fluid motor position feedback control system, is also applicable to the load adaptive fluid motor open-loop coii~tr~l system.
A significant dynamic performance superiority of any~pressure drop feedback control system ag~,ins~t the fluid motor open-loop WO 99/b4761 55 PCTNS98/12200 -control system can be established, for example, by providing basically a. significantly larger closed-:Loop bandwidth for this pressure drop feedback cowtrol system in comparison with an open-loop crony-'over fre uenc q Y of the fluid motor open-loop cowtrol qyst em ~..
General principle of coordinated control:
the constructive effect of motor load.
As it is already mentioned above, a regenerative adaptive fluid motor control system is typically a combination of at least three component control systems - a fluid motor control system, at least one exhaust line pressure drop feedback control system, and at least one supply line pressure drop feedback control system. .The-fluid motor~control system may or may not include the output feedback control means.
Let's assume that for any given regenerative adaptive fluid motor control system:
(1) all the separate component systems are dynamically stable ( and provide the required dynamic performance ) and (2) the general criterion of dynamic stability of combined component systems is satisfied, which. means that:
the concept of preventing~a schematic operation interference, which was presented above, has been already properly implemented;
(b) the concept of providing a significant dynamic performance superiority, which was presented above, has been also properly implemented;
(c) the concept of preventing a pressure drop regulation interference, which was presented above, has been also properly implemented.
Under all 'these preconditions, one general principle can now be formulated, in order to clearly visualize why all the component WO 99/64761 56 PCT/US9$/12200 -systems will be working in unison to provide an operative regenerative system. This "general principle of coordinated control" can be formulated as follows:
In a regeoer~tive adaptive :fluid motor control. sys~tem~
the component/ systems will. not interfere and will not "fa.lJ. a part" , but i.ns~tead will be working in unison, i;o provide an operative regenerative system,by virtue of rowtrolling all 'the pressure drop feedback cowtroJ. systems from onJ.y one "mi~,jor coordinating cewter"- ~thal: is' by i;he only ore (total) motor load. This general principle reveals the constructive effect of motor load.
In order to illustrate this principle more specifically, let's consider, for example, a regenerative adaptive fluid motor c9rive system for the motor vehicle. In accordance with figures lU, 11, 16, and 17, the magnitude and direction of rnoLor .toad of motor 1 are conveniently measured by the pressure signals PU2 and P~5. These pressure signals can also be viewed as the load related, input-command signals for the supply and exhaust line pressure drop feedback control systems, respectively. It means that all the pressure drop feedback control systems are, indeed, controlled in unison by the motor load of motor 1.
Finally, it can also be concluded that in the load adaptive motor vehicles, the vehicle speed is controlled by the driver via the fluid motor control system, while the energy supply and regeneration processes are all controlled in unison by the motor load via the pressure drop feedback control systems.
1n short, the load adaptive motor vehicle drive system is, indeed, an operative regenerative system having all the components working in unison.

WO 99/64761 S~ PCT/US98/12200 -SOME EXAMPLIfIED SYSTEMS
Adaptive fluid control and the motor vehicles.
motor The load adaptivT~e vehicle drive systems, like the one shown on Fi.g.l7, may have advantages against 'the conventional motor vehicle drive systems in terms of such critical characteristics a.s energy efficiency, environmental efficiency, reliability, controlability, and dynamic performance. Some of the underlying considerations are:
1. By virtue of the load adaptability, the task of controlling the.speed of the motor vehicle is conveniently separated from the 'tasks of controlling the energy supply and~conservation.
2. The primary supply fluid pressure drop regulation by 'the variable speed primary motor (engine) 92 has an effect of the energy supply regulation in accordance with the actual energy requirements. ., ~e lation 3. The e~chaust fluid pressure drop the ndspendsrt regenerating c?rcuitry make it po~~ible to create the schematic conditions. under which the energy accumulated durin~c the deceleration of the motor vehicle is reused dur:rg the following acceleration of the motor vehicle.
The energy accumulated during the vehicle down-hill motion will also be reused.
/~. At the presence of load adaptive control, a standart braking system of the motor vehicle can be used mostly as a supplementary ( or emergency ) braking system.
5~ In the load adaptive motor vehicles, a relatively smaller engine can usually be used.
6. Moreover, this smaller engine can be substituted by 'two still smaller engines, only one of which is operated all the time, while the second engine is switched-in only when needed - for example, when the vehicle is moving up-hill with a high speed, as it will be explained more specifically later.

WO 99/64761 5g PCT/US98/12200 -7 ~ The :sir pollution effect of 'the motor vehicles will. be substantially reduced dust by eliminating the waste of energy engines, and brakes.
8. ~n the load a.da.ptive motor vehicles, no controlled mechanical transmission is needed.

9' The schematics of figures 11, 16, and 17 can be modified by replacing the variable speed primary motor 92 by the constant speed primary motor 100 and by using the variable displacement means 93 of pump 90 for regulating 'the supply fluid pressure drop P2 - p02 -~ p2 ~ as it was already illustrated by F1g.12.
daptive rluid control and the City Trans it Buses.
The load adaptive drive system, such as shown on Fig. l7, is especially effective in application t o the buses which operate within 'the cities, where a stop-and-go traffic creates the untolerable waste of energy, as well as the untolerable level of air pollution.
Le't's assume , for simplicity, that the bus is moving in a horizontal direction only. pad let's consider, for exa-nple, the process of bus deceleration -- acceleration beginning from the moment when the bus is movi;~r with some average constant speed and the "red light~ is ahead.
Up to this moment the spool of valve 2 have been hold pushed partially down by the drive Jso that this valve is partially open.
In the nrocr~RS ef bus deceleration the spool of valve 2 is being moved up- to close this valve;
the pressure Pos in line Lw is increasing, the pressure pj in lineLS is also increasing the exh~u~t fluid energy of the exh~.ust fluid flow is berg trars~ritted through motor 66 to the flywheel accumulator 94 . . . , As the spool valve 2 is finally closed, the bus is almost stopped and the complete stop is provided by usin~_ the bus brakes - as a dually.
In the process of bus acceleration .
the spool of valve 2 is being moved down - to open this valve;
the pressure ~oZ in line L1 is increasing;
the dressures ~G and ~ ~ are also increasing; however and therefore check valve 44 is open, and check valve 40 is closed=
the energy accumulated by flywheel 94 is transmitted through pump 55, check valve 44, lines L2 and L1 to the motor 1.
when the erer~ry accumulator 94'is almost discharged, the Pressure ~Z,e is being dropped so that the check valve 44 is closed, and the check valve 40 is open per~ittirF the engine 92 to supply the power flow to the fluid motor 1.
The load adaptive drive systems, like the one shown on.
Fig. l7, can also be characterized by saying that these d rive systems incorporate the energy regenerating brakes.
Adaptive fluid control with the hydraulic accumulator.
The regenerative adaptive fluid control schematic which .s shown on Fi~r.l8, can also be used for the motor vehicle applications, and in particular, for the buses which operate within the cities. This schematic will be stud »d by comparison with the one shown on Fig. l7.
The fly~.wheel 94 shown on Fig~.l7 is substituted by a hydraulic accumulator 122 shown on Fig.lB. Accordingly, the exhaust line variable~displacement motor 66 is repl2ced by the exhaust line constant displacement motor 116 driving zhe exhaust line variable displacement pump 120 which is powering the hydraulic accumulator 122 through check valve 136.

WO 99/64761 6o PCT/US98/1Z200 -'fhe exhaust; line variable displacement pump 120 is provided with t:he variable displacement means 130 Which i.s used to maintain counterpressure PS ,- P05 a PS in t:fre exhaust power line L5 - as before. In other words, a counterpressure transformer including fluid motor 116, shaft 11U, fluid pump 12U, tank .Lines 7~1~ and ~.~4, and power lines 78 and 132, is irnp.lemented to rnake up the counterpressure varying and energy recupturing~
means o.C the exhaust line pressure drop feedback control system maintaining counterpressure P5 ~ P05 - ~,PS in the exhaust:
power .line L5.
The ~~ss~. ,ting variable displacement pump 55 is replaced by tare aSSlstlng constant displacement pump 114 being driven by the assisting variable displacement motor 118 which is powered by the hydraulic accumulator 122. The assisting variable displacement motor 118 is provided with the variable displacement means 128 which .is used to maintain pressure P2RW P02+~~P2R in. the line 30, as before. In other words, a pressure transfor.rner..
j.nc.luding fluid pump 114 , shaf t 112, f laid motor 118. tantc l.ine:>
36 and 126, and power lines 30 and 124, is implemented to make yo tire assisting variable delivery fluid power supply of the ' assisting sulyiiy line pressure drop ~eedbaclt control system maintaining pressure P2R - P02 ~'.;'~P2R In the line 30~-Adaptive fluid control:
the combined energy accumulating means.
It is understood that many other modification and variations of regenerative adaptive fluid control schematics are possible. These schematics may include the fl~.wheel, the hydraulic accumulator, the electrical accumulator, or any~, combined energy accumulating means. -_- -~. __ -_. ___----The exemplified schematic showing the combined energy accumulating (and storing) means is presented by Fig. l9 which is basically a repititfon of Fig.lBr however,~~two ma~vr components are addeds.the electrohydraulic energy converting means 1~2 and the electrical accumulator 144..
Its addition, and just for diversity of ,the drawings presented .
the variable speed primary motor 92 is replaced by the constant speed primary motor 100, so that now the variable displacement mechanism 93 of pump 90 is used for regulating 'the supply fluid pressure drop P~ - PO2:_-_~,PZ , as it was already illustrated by Fig. l2. As the hydraulic accumulator 122 is almost fully charged, an excess fluid is released from this accumulator, and a hydraulic energy of the excess fluid is converted through the electro-hydraulic energy converting means 142 ~to the electrica' energy o,f electrical accumulator 144.
On theother hand, as the hydraulic accumulator is almost fully discharged, the energy is transmitted back from the electrical accumulator lti~~ to the hydraulic accumulator 122.
The schematic of Fig. l9 can be characterized by that the combined energy accumulating (and storing) means include the fluid energy accumulating means being implemented for powering the electrical energy accumulating means. More generally, the combined energy accumulating (and storing) means may include major (primary) energy accumulating means being implemented for powering supplementary (secondary) energy accumulating means.
Note that a common electrical power line can also be employed as an equivalent of the energy accumulating (and storing) means.
For example, the combined energy accumulating (and storing) means may include fluid energy accumulating means (hydraulic accumulator 122 on Fig. l9 ) being implemented for powering the electrical power line (replacing electrical accumulator 144 on Fig. l9 ). In this case, the electrical power line will accept an excess energy from the hydraulic accumulator 122 and will return the energy back to the hydraulic accumulator 122 - when it is needed.

WO 99/64761 62 PCf/US98/12200 -,. .._ ___ Adaptive fluid control.
with a variable displacement motor driving the load.
r,.g.20 is basically a repetition of I~ig.lti~ however, the v~,ra.alale speed primary motor 92 is introduced now by the vari.a.ble speed primary. internal-combussivn engine 92.
- :Cn .~~ddi~L~.on. the ~' . .~}ie ...
constant displacement motor l,driving"Toad 96 is replaced by a variable displacement motor 150 driving the same load.
Tt~e variable displacement means 152 of motor 150 are construci;ed i:o make-up the displacement feedback control system including a variable displacement mechanism (of motor 150 ) and employing a displacement feedback control errow si~nai D D, Thf~~nal is generated in accordance with a difference between a spool displacement ( evmmand signal ) Do of valve 2 and, a mechanism displacement ( feedbaclt signal ) D1 of the variable di~splacemewt mechanism of motor 150. The displacement feedback control errow signal ~ D - Do - D1 is implemented for modulating the variable displacement mechanism of motor 150 for regulating the mechanism displacement D1 of the variable displacement mechanism of motor 150 in accordance with the spool displacement Uv of valve Z. It should be emphasized that the displacement feedback control system, which is well known in the art, is, in fact, the position feedback control system and that, therefore, the general position feedback control technique, which is characterised above with respect to the fluid motor position feedback control system,, is also basically applicable to the displacement fesdbtrck control~system.
As tt~e spool of valve 2 is moving clown from tile"zero" trosition ;shown on Fig.20, there are two consecutive stages of speed regulation oi' motor 150 , the lower speed range is produced by chr~ngmg the actual (orifice ) opening of valve 2, l:he higher speed range is.produced by changing the displacement of motor 150. S peaking more specifically , the lower speed range of motor 150 is defined between the "zero" spool position and the point of full actual ( orifice ) opening of valve 2. Up to this paint, the command signal Do is kept constant, so that the displacement of motor l,~fl is maximum and is not changed.
The higher speed range of motor 150 is located beyond the point of full actual ( orifice ) opening of valve 2. Beyond this point ( due to the spool shape of valve 2 ) the further spool displacements do not change any more the opening of valve 2. On the other hand, beyond this point, the c:omm~na algn..,l. Do is being reduces by tcse furzner spool displacements of v,~lve 1. Accordingly, zne displacement Dl~ Do-~D of the vtcriable .displacement mechanism of motor 150 is being also reduced by the displacement feeuback control system. The smaller the displacement of motor 150, the higher the speed of this motor ( and the smaller the available torgue of this motor ) .
Fig.20 also illustrates t he use of check valves.for restricting the maximum and minimum pressures in the hydraulic power lines. The check valve 154 is added to very efficiently restrict the maximum pressure in the exhaust motor line L4 by relieving an excess fluid from this line ( through check valve 15~E ) into the high-pressure hydraulic accumulator 122.
The check valve 155 is added to effectively restrict the minimum pressure in the supply motor line L1 by connecting this line ( through check valve 155 ) with the i:ank 62.
rote th2.t tank 62 can generally be replaced- by a low-pressure hydraulic a.ccumula.tor ( accompanied by a small-supplemetary tank ) .

~d~.ptive fluid control with a regenerative braking pump.
In the motor vehicles, such as the City Transit Buses, the available braking torque should be usually substantially larger than the available accelerating torque.
Fig.21 is basically a repetition of Fig.la ; however, the constant displacement motor 1 driving the load 96 is also driving a regenerative braking variable displacement pump 170 which i.s used to increase the available regenerative bralciry 'torque . The 'tank line 176 of pump 170 is connected to tank 62. The pressure line 1?t3 of pump 1'70 is connected through check valve 174 to the hydraulic accumulator 122.
The flow output of pump 1~0 is regulated in accordance with i;he pressure rate P05 in the motor line L~~ conducting a mot or fluid flow from the fluid motor 1, as it is more specifically explained below.
The variable displacement means 99 of pump 170 are constructed to make-up a displacement feedbacl.~control system including a variable displacement mechanism ( of pump 170 ) and employing ei' ow a displacement feedback control arrow signal O d. 'fhis~' sigrza~. is general:ed in accordance with a difference between a command-displacement signal do = C~ P05 ( where Cp is a constant coefficient ) and a mechanism displacement ( feedbaclc signal ) dl of the variable displacement mechanism of pump 170.
A pressure-displacement transducer converting the pressure signal P05 to the proportional command-displacement signal do = Cp P05 is included into the variable displacement means 99 of pump 170.
This transducer may incorporate, for example, a small spring-loaded hydraulic cylinder actuated by the pressure signal QpS, The displacement feedback control arrow signal ~ d ~ do - dl is implemented for modulating the variable displacement mechanism of pump 170 for regulating the mechanism displacement dl of the variable displacement mechanism of pump 170 in accordance with the command signal do and hence, in accordance wit?~ the pressure rate WO 99/647b1 65 PCT/US98/12100 -P05 _- do/Cp in the motor line L4 ).
It should be emphasized that the displacement feedback control system, which is well known in the art, is, in fact, the position feedback control system and that, therefore, the general position feedback control technique, which is characterised above with respect to the fluid motor position feedback control system. is also basically applicable to the displacement feedback control system.
In general, the displacement feedback control circuitry of pump 1~0 is adjusted so that, while the pressure P05 in the motor line I~~ is comparatively low, this circuitry is not operative 'and dl ~ 0. As the pressure POs in the motor line LlE is further raising-up, the displacement dl of pump 170 is increasing~acdordingly, so that the total regenerative braking torque is properly distributed between the fluid motor 1 and the regenerative braking pump 170.
Note that a significant dynamic performance superiority must be provided for the displacement feedback control system against the energy recupturing (recuperating) pressure drop feedback control system, in order to prevent their substantial dynamic operation interference. The concept of providing a "significant dynamic performance superiority ".have been already generally introduced before and is further readily applicable to the displacement feedback control system versus the energy recupturing (recuperating)'pressure drop feedback control system., WO 99/64761 66 PC'T/US98/12200 -adaptive fluid control patterns.
r.r.g..7_Z is basi.c:all.,y a repe~ti.ti.on of r.~.g.~0; however, t)te variable speed pr imary imtarnal-combussion engine g2 is now .r. epl.aced by a r. alai:i.vely cons~trrrot speed primary internal-combussior_ engine 100, while -the varialtnle displacement pump 9U is adapi;ed now :for maiwtaming U;he hr.essure P~ ~ P02 ..~p,P2 i.n line StT, as i.~t was already illusU;ra~ed, for example, by I~ig.lg. In addi~tiorr, ~t:he vari.a.lrle d.i.splacemewl: motor 11>3 snd 'the constaol; disp.l.acement Fc.rmh 11~1~ are replaced by U;he consl;anl;
rlisplacement: mo~to.r 19f3 and the variable dispJ.acemewt pumja lg~ts in orc9er to provide a wider r.~.tiQe o.f regulation of lrressure, f2R = f02+~ P2R ''r1 llrte 30' 'flte assisting constant displacement motor 199 3s powered by the trydrcrul.fc accumulator I22 ( through shut-off valve,~99 ) and .is driving the assisting variable displacement pump I94 wl~.iclv i a pumpi ng the ol.l :Crorn trrntc 62 back into the accumulator 122 ( t:lrroug)r check valve ?.0~ and shut-vff valve 299 ) . Jlctua.L.ly, t:lte output: flow rate of accumulator 122 (in line 2..tU) i.s equal to a difference t~etween the input flow rate o:C motor 198 (in line 2UU) and the output flow rat:e~ of pump 199 ( in 1 ine 1.7.1 ) .
'.t'It~e~~~~~~st from motor ).gt3 is used 'to power the line 30.
flte iar~'i1"a.~e di.splacemewt means 196 of pump l9tr is modulated by tl~S~jo~~e drop feedback signal F28 - P()2 'to maiwta.irr pressure P2P= P0? ~-~.P2R '.t' l~.ne 3U-a..s before. Time torqus of pump :191N couwterbalance s isle 1: orque of motor 1913 . ~s ~tne displacement of pump 19~E is varied ( b,y 'Lane assisting supply line pressure dro_~ 1'eecibuclc ~C he coni;rol. sys~cem ) f.r~mv"'tna.ximum" ~o "Tero", ~tlte pressure F2,1T .i.n line 30 can be regulateri from ~'37.most zero" ~r,o Mire wnmx~.mum", ac:cor.~dir~gl,y. The check .valve ?Uf3 ~nnnec~ts l..i.ne 132 ( n,(' pump 7_20 ) w.t~:l~ i:he ~tanlc ~b2.
The shut-off valve~299 is controlled by the load pressure signal P02. The check valve 208 and shut-off valve 299 WO 99/64761 6,~ PCT/ITS98/12Z00 -are considered to be optional and are introduced only -to illustrate mor. a specifically Borne exam-plif~.ed'~ patterns of control.la.ng ~tle load adaptive exchange«.t' energy between tare fluid motor acrd load means and i:ne energy ar.cumu~.wting means. ~rhe rslatec9 explan~i;i.or~s are presented below .
het's C0r1Sl.der, first, :r simple casE~, vilren the moi:or vehicle is rnovi.ng in a horizowtal:= direci:ian only. While the motor vehicle is moving with a constant speed ( or is being accelera~ted)~ the pressure f05 ( o.n line TJ~ ) is very small and does not eff ect the ini~tia.l displa.cemerrt o:f pump 120 provided that pressure drop command signals ~,P2, L~ P2R~and d P5 are selected so that ,d P5 ~ d P2R ~~P2 as it is required by expression (3).
This initial pump displacement is made just slightly negative, i n order to provide for the pump J.20 a very small initial output ( m line 131 ) directed to the tar~lc 62, and they eb,y, i:o provide i'or the exhaust fluid flow (i.n line L5 ) a, free passage through ~ motor 11.6 to 'the tank 62. In oi:hnr words, while the pressure signal )1'05 is very small, -the cneclc valve 20a is open, the check valve 136 is closed, end the pump 120 is actual).y disconnected :from 'the accumulator 122.
An tire motor vehicle is being decelerated, the displacement of pump 120 is positive, the check valve 20f3 is closed, the check valve 1j6 is open, and the kinetic energy of d vehicle mass is converted to the accumulated energy of accumulator w 122, as it :~ ready explained above.
In ~~ general. case, the motor vehicle is moving in a~ horizontal.
direct:ron, up-hill., and down-hill, and with ~tl~e different speeds, accelerati.orns, end decelerations; however, all what countSfor controlling the energy recupturing pressure drop feedba.elc corrtrol. system, is the load ra to and direction ( which are measured by the pressure signals POS and P~2 ). While the pressure signal Pd5 is ~~ery small, the pump 120 is WO 99/64761 6g PCTNS98/12200 -actually disconnected from the accumulator 122, dnd the exhaust fluid flow is passing freely through motor 116 to the tantc 62. ps the pressure signal P05 is increasing, the kinetic energy of a vehicle mass is converted to i;he accumulated energy of accumulator 122.
Un the other hand, all what countffor controlling the primary and assisting supply line pressure drop feedback control systems (and the shut-off valve 299,), is also just the load rate and direction (which are measured by the load pressure signals Pp2 and Pp5 ). While the pressure signal P02 is very small, the shut-off valve 299. is closed. After the pressure signal P02 is measurably increased, the shut-off valve 299 is open.
In shoe t, i;here are many r. egeneral:ive adaptive fluid control pa't'terns which are basically adaptive to a motor load, while ~.re a..lso responsive to 'the specific needs of pa.rticul.a.r applications . pll the variety of the regenerative ada.p~tive fluid control pa't~terns is~fact, within the scope o:f i:r~is invention. Fig.22 is still further studied later - with the help of supplementary figures 23 to 25.
Adaptive fluid control:
two mafor modifications.
There are two major modifications of adaptive fluid control having an independent regenerating circuitry. The first major modif.tcation is identified by using the variable speed primary motor 92 for regulating the primary supply fluid pressure drop, as illustrated by figures 11, 16, 17, 18, 20, and 21. The second major modification is identified by using the variable displacement mechanism of the variable displacement primary pump 90 for regulating the primary supply fluid pressure drop, .as illustrated by figures 12, 19, and 22.
It is important to stress that these two major modification are often convertible. For example, the schematics sho::~ on figures 11, 16, 17, 18, 20, and 21 can be modified by replacing -the variable speed primary motor 92 by a constant speed primary motor 100 and by using the variable displacement rimar mechanism of pump g0 for regulating ~e su p y fluid pressure drop P2- P02_~. P2 i as it is illustrated by figures 12, 19, and 22.
Toe transition to the modified schematics is further simplified by providing a constant speed control system for the variable speed motor 92 and by converting, thereby, this variable speed motor to d cons.tdnt speed motor.
Regenerative adaptive drive systems.
It ;should be emphasized that the combined schematics providing an automatic transition from the .one mode of operation to U;ne oi;her are especi.all,y at:~trac~tive for i;he moi;nr vanicle applications. The exau~p7.ified modifications of combined scnem~~t;ic:~ ca.n he br. iefty cnaracteri~ed ~s follows.
: l.. The motor vehicle is firs U: accelerated by a.c~tuai;ing the variable di~l~cemenV; mechanism of pump 90 - as illus~tra~ted nn~
by Fig.22;Y3'~' further accelerated by s~c~traai;ing 'the variable speed primary intorrial-c:ombus:~ion engine - as i.lluwtr.ated by Fig.20. This first modification of combined schematics can be viewed s~s a basic ( or first ) option of operation.
2. The motor vehicle is first acceler~rted .by a.ctuai:ing -tae variable di.spl.~cement rnechanis:n of pump 90 - as illus~tra.~ted by Fig.22, is further accelerated by actuating the vari~,bl.e WO 99/64761 7o PCT/US98/I2200 -speed primary i.wterna:L-c:ombussion engine - as .j.l.lustr.~tted by Fig.2l~, sad i;i stil.l further ~tccelorated by actuating ~t:t~e veri:,ble displacement mechanism of motor 150 - its i.llustral:ed by figures 2U r,nd 22. Note t;lwl; i.n H,nis cnr~e, U:Ite eng.i.ne will be usually .Gully landed only during U:ne third stage of speed regulation - ,just after the displac:ernent of motor 1.~0 i.:;
sufficiently reduced. Note also tltal; the minimum possihle displacemert-t of motor 1~0 must be r estricted by 'the desirable _ maximum of engine load ( which can he measured, for example, by the desirable maximum of pressure P~? :in line L1 of motor :LjO ) .
3- The.motor vehicle is first accelerated by actuating the variable displacement mechanism of pump 90 - as illustrated by Fig.22, and is further accelerated by actuating the variable speed primary internal-combussion engine - as illustrated by Fig.20. Contrary to point 2, there is no third consecutive stage of speed regulation ( by using the variable displacement motor 150 ). Instead, the displacement of motor 150 is controlled independently by using the pressure signal P02 which is provided by line L1. The larger the pressure signal P02 , the larger the displacement of motor 150 - within the given limits, of coursa, ~4. The motor vehicle is provided with two relatively small engines. The first engine is usually,in operation all the _ switched-~in ~f:irne. '('Ito second engine i.s u;~ual).y~~ly l:amporarily, while 'the motor vehicle ict moving up-hiJ.l with a high r3lteed.
L;~c?t ent~i.ne is driving s~ scrp;tra.te pump ( like pump 9U ) .
Is'ach engine-pump insta.l.ation is worlcinp, with a separate spool ~~l.vn { :L.i.lc~~ .~yoc~l. v~:l.vr 7 ) .
j. '1'ha ranc:orul oyt.i.orr o.C opra~t.'ton (~ :;c~c ho.i.nt 2 ) is ;~ypl.i.ed i:o U:lte fi.r.~rt eng.Lne-pump .in;;~talation: of 'the two-.engine vehicle of point: ~E~
ti. The first; option of ctpcrranon ( ;gee ltoi.nt 1. ) is applied ~t:c~ 'the ;second en/;ine-pump i.n,~.t;v7.atiot~ o.C i:he two-engine veltic).c oC tiol.rrl; ~I~.
7. '1'he -I:hi.rd option o.C opera t;i.on ( ;~eP point 3 ) .in WO 99/64761 ~ i PCT/ITS98/12200 -:yirl.i~d t;o. ~th~ fir. si; en/;ine-pump a.nsl:alr~i:ioo of ~t;he ~t:~vo-en~;3.ne vehicJ.e of point; ~+.
F3. 'fhe i;hird option of. oyorwC.i.on ( gee poiwt; ~ ) is, also ~ppli.~d U;cr -t;hn second engine-frump .i.nsi;a:le.i;ion of i:he l;wn-eryine vehicle of point ~/, , 9. The independent regenerating circuitry, such as shown on figures 11 to 22, can be easily switched-off by the driver in the process of operating a motor vehicle. This can be accomplished by using a directional valve switching over the exhaust power line L5 from the energy regenerating circuitry to the tank.

10. Note that regenerative adaptive drive system, such as shown on fig.22, can be modified by replacing the "stationary"
exhaust line energy recapturing means ( the constant displacement motor 116 driving the variable displacement pump 120) and the "stationary" assisting variable delivery fluid power supply (the constant displacement motor 19a driving the variable displacement pump 199) by only one "shutle-type" motor-pump instalation including a constant diplacement motor driving a variable displacement pump. Let's assume, for example, that wheeled vehicle is moving in a horizontal direction only.
While the vehicle is decelerated, this motor-pump instalation is switched-in to perform as the "made-up" exhaust line energy recapturing means. While the vehicle is accelerated, this motor-pump instalation is switched-in to perform as the "made-up"
assisting variable delivery fluid power supply.
Integrated drive system. .
The energy regenerating, load adaptive drive system of a wheeled vehicle can be still further modified to provide an optional mechanical connection of the engine shaft with the wheels of the vehicle. This optional mechanical connection WO 99/64761 ~2 PC'T/US98/12200 -can be used, for example, for long-distance driving.
'fhe d~Sign of modified-integrated drive system may include an integrating mechanical transmission to select one of two alternative - component systems as follow 1. The basic regenerative adaptive drive system - see Yigures 17 to 22. In this~case, the engine of a vehicle is connected with the primary pump 90. The back axil of a vehicle is driven by the constant displacement motor 1 (or by tloe variable displacement motor 150).
2. The optional conventional power train. In this case, the shaft of the engine is connected mechanically to the back axil of a vehicle.

WO 99/64761 ~3 PGT/US98/12200 -CONCLUSIONS
R_e4enerative adaptive fluid motor control: , the energy recuperating pressure drop feedback control system-A regenerative adaptive fluid motor control system having an i.odependewt regenerating circuitry (see figures 11 U:o i2) a i.~s art i.nU;egrai:~ sysvem incorporating only U;wo major components r ~---ed n ) ~I;he ~I;wo-way J.oad ada.p~l;ive fluid mo~t;or cowl;rol. aya I;em wl~.i.clr is sdapl:ive 'I:o ~I:he motor Loan along .l:I~e exiwxr,U; and snl~pl.y power lines o.f U:l~e- spool valve 2, and ti) U,l~e l;wo-way toad adaptive energy regenexwt:3.ng sys~I;Fm wlri.otr is a3.c~o adaptive 'I;o vhe motor load along ~i:he exhm.tsi: anti s~.rpp7,y power. 7.3.nes of the spool. valve 2.
..
The regenerative system having an independent regenerating circuitry is charactirized by that the primary and assisting supply line pressure drop feedback control systems are separated.
On the other hand, the exhaust line pressure drop feedback control system (which can al.sv he referred yo a~ l;he~ energy recupi:uririg px-esscare drop feedt~;,clc conl;rol system ) is shared be~l;ween ~I;ire ~t;wo-w7y l.ond ed:~pU;ive .C:Lu.i.d motor control sysi;ern and l;he I;wo-way J.oad ~ds,pi;ive energy regenc~ra:t:ing sysl:em.~ The energy x~ecr.yla.t.r.iry E~ressure drop feedlJack control sys~l;em includes rcn pxlmuwl: l..i.ue enerl;y r ecitp~l;uring means for varying s~ cvunterpressurv .rake in I:l~e Axhr~.usl; power line and :for recup~l;uri.ng a J.oECCI rel.al;ed energy, such a.s a-kinei:ic energy v.C_a load mass or a comyx-ecsed fluid energy of a fluid motor-cylinder. The energy recupturing pressure drop feedback control system and the exhaust line energy recupturing means can also be referred to as the energy recuperating pressure drop feedback control system and the exhaust line energy recuperating means, respectively.
Load adaptive energy regenerating system.
_._.~..... .. _.___ ~...._ ._... _._, ~l'he r:cbove lxrief description of examplified load aclapU:ive energy x~egeneral:ing syat;ems ( .see figures 11 to 22~ ) can 1~e a C.i.l:l.

furthep generalized and extended by the comments as follows.
1. In a load adaptive energy regenerating system, there. are basically four r~a,i r c m1nonentsr -the fluid motor and load means , the f. ~rst"'lene~~cbnvertin~t me ns , the energy d ~~ap,W ve accumularting means, and the secon nergy converting means.
2. The fluid motor and load means include 'the fluid motor means and the motor load means and accumulate a load related energy ( such a.s a kinetic energy of d load mass or a compressed fluid energy of.the fluid motor-cylinder ) for storing a.nd subsequent regerieration of 'this load related energy.
3. /1s it was already mentioned before, the "exhaust fluid energy" of the exhaust fluid flow is understood as a measure of the load related energy being transmitted through the exhaust power line (that is line L3 or line L5). The "exhaust fluid energy" can also be referred to as a "waste fluid energy", that is the energy which would be wasted unless regenerated.
4. The f~'rs en g converting means include the energy recupturing pressure drop feedback control system and convert the load related energy of 'the fluid motor and load means ~ to an accumulated energy of the energy accumulating means for storing and subsequent use of this accumulated energy.
The high energy-.efficient, load adaptive process of converting the load related energy to the accumulated energy is facilitated by regulating the exhaust fluid pressure drop across spool valv~ 2 by the energy recupturing pressure drop feedback control system and is basically controlled by the motor load. Note that 'the energy is being accumulated by 'the energy accumulating means, while 'the motor load is negative ( fox example, during the deceleration of a motor vehicle ).
1 oadv~
5~ The second~en~e_rgy converting means include the .. assisting supply line pressure drop feedback control System and convert the accumulated energy of the energy accumulating means to an assisting pressurized fluid strearn being implemented for powering the supply power line L2 of spool valve 2. The assisting.
pressurized fluid stream is actually generated by an assisting WO 99/64761 ~5 PCT/US98/1ZZ00 -variable delivery fluid power supply which is included into 'the assisting supply line pressure drop feedback control system and which is powered by 'the energy accumulating means.
The high energy-efficient, load adaptive process of converting the accumulated energy to the assisting pressurized'fluid stream i.s facilitated by regulating the assisting supply fluid pressure drop across spool valve z by the assisting supply line pressure drop feedback control system end is basically controlled by the motor load.
Note that ~I:he energy is being released by the energy accumulating means, while the motor load is positive ( for example, during the acceleration of the rnotor vehicle ).
6. Because the accumu7.ation, storage, and release of the accumulated energy are all controlled by 'the motor load, l;he load adaptive energy regenerating system, as a whole, is also basically cone rolled by 'the motor load.
'7. It can also be concluded that:
(a) the regeneration of a load related energy of the fluid motor and load means is facilitated by regulating the exhaust fluid pressure drop across valve 2 by the energy recupturing pressure drop feedback control system (b) the regeneration of a load related energy of the fluid motor and load means is also facilitated by regulating the assisting supply fluid pressure drop across valve 2 by the assisting supply line pressure drop feedbaclt control system.
Regenerative adaptive fluid motor control system.
The above brief description of exampiified regenerative adaptive fluid motor control systems (see figures 11 to 22) can be still further generalized, and extended by the comments as follows.
1. The primary supply line pressure drop feedback control system ?.ncludes a primary variable delivery fluid power supply generating a primary pressurized fluid stret3m being implemented for powering the supply power line L2 of the spool valve 7. 'The assisting supply line pressure drop feedback WO 99/64761 ~6 PCT/US9$/12Z00 -control system includes an assisting variable delivery fluid power supply generating an assist3.ng pressurized fluid stream being a.l.so implemented for t.~ower~i.ng the supply power line L2 of the spool valve 2.
2. Note that assisting pressure rate P2R-P02'~'~P2~
of the ~ assisting pressurized fluid stream i.~s being correlated w.i.th the primary pressure rwLe P2 'lP02 +''aPZ of the primary pressuri7 ed fluid stream. Note also loaf l,P2R~p.P2 and, tnerefore, P2R > P2 , wnile there is still any meaningful energy left in the energy accumulator.
3. In accordance with point 2, the assisting pressurized i.luid stream has a priority over the primary pressurized fluid stream in supplying the fluid power to the supply power line L2.
4. Speaking more generall y, it can be concluded that:
regeneration a! a load related energy of the fluid motor and load rneans i~ accomadated by correlating the primary pressure rate of t:he prirnary,pressurized fluid stream with the assisting pressure rate of the assisting pressurized fluid stream by regulating tt~e primary supply fluid pressure drip across valve 2 and regulating tl~e assisting supply fluid pressure drop across valve 2 by the primary supply line pressure drop feedback control system and the assisting supply lime pressure drop feedback control systern, respectively. .
5. The exhaust line energy recupturing means of the energy recupturing pressure drop feedbaack control systems can be introduced by the exhaust line verifible displacement motor 66 - see figures 11, 1.2, 16, 17, or by the exhaust line constant displs~cement motor 116 driving the exhaust line variable displacement pump 120 - see figures 18 to 22.
6. The assisting variable delivery fluid power supply, which is powered by the energy accumulating means, can be introduced by the ~~ assistingw variable displacement pump 55 - see figures , 11, 7.2, 16, 1.7, or by. the Hssisting variable displ.sicement motor 118 driving 'the assisting constawt displacement pump llrt~ -- see :figures 18 to 21.
The assisting variablle delivery fluid power supply can also be WO 99/64761 ~~ PCT/US98/12200 -introduced by the assisting constant displacement~motor 19F3 driving the assisting variable displacement pump 194 - as it iJ
illustrated by Fig.22.
7. ~ The 'primary variable delivery fluid power supply can be introduced by the primary variable displacement pump 90 - see figures 12, 19, and 22 or by the variable speed primary motor ( or engine ) 92 driving the primary fluid pump - see figures 11, 16, 17, 18, 20 and 21.
8. In accordance with points 5, 6, and 7 and the above description, any pressure drop regulation is accomplished by the related pressure drop feedback control system by implementing the related pressure drop feedback signal for modulating one of the following:
a ) tt~e variable d i.sglacement means of -the variable displ.acemewt pump , b) the variable displacement means of ttie variable displacement motor, c ) l:he variable speed pr imary motor ( or U;he varis~.t~le speed primary engine ) dri.ving 'the primary fluid pump.
9. ~ The variable displacement pumps having the build;- i.n pressure drop feedba.clc controllers are well )crown a.n U:he a.r t .
This I:ype of control for the 'variable displacement pump is often called a "load sensing control" and is described in many p:,tents and publica.tioeas ( see, for example, Budzich--U.S . Patent; No.4, 071E, 529 of Feb.2l, 1976 ) .
Moreover, the variable displacement pumps with i;he load-sensing pressure drop feedback controllers a.re produced (in ~ mass amount )~ by many companies which provide catalogs send other in:foxmation on this load sensing cotrtroJ..
Some of 'these companies are, .
a) TIIE OII~EAR COMPANY, 2300 South. 5lth Street, Milwaukee, WI ~32~.9~ U .S . A. ( see, for example, Bulletin 47016A ) b ) ~ SAUER-SUNDSTRAND COMPANY , 2800 East 13th S treet , Ames IA 50010, U.S.A. ( see, for example, Bulletin 9f325, Rev.E );
c) DYNEX/RIVETT, INC., X70 Capitol Drive,~Pewaulcee, WI $302, I1.S.A. ( see, for example, Bulletin PGS-12139 ).
rur~therm~re, ~i:he addit9.ona1 information of general nature orr WO 99/64?61 ~g PC'T/US98/12200 -Lhe feedt~:~clc cowtrvl sysi:ems and the hydraulic corntrol. gys~tems is =also rezndily avail.abl.e fran many publica~ti.ons - sea, :('or ex:~mple, U:he hooks already named s~bove. ~ In short, O:he luacl-Se~n~i.nQ pressure drop feedbncic cowtroJ.J.ers of i;l~e vori.~bl.e displacemerrt pumps are. indeed, well known In i;he Art.
.tU . Comparing poinl;s ; 8 and 9 t i~t can be concluded ~tlia~t 'the load ada.pi;ive variable displacement means ( o.f i;he variabJ.e di.splacemerrt pumps and 'the variable displacemewt motors ), whictr are used :in i;his 3.nvewti.on, are basi.caJ.ly similar with the well-lcnown.load-sensing pressure drop :.feedb~c)c c on~trol.lers of the variable d ispl~cemenl; pumps . 'fhege l.oa~d .a.dap~t;i.ve displacemewt means can also be .reffiered i;o as 'the load adaptive displacernen~t cowtrol.lers .

11. It. is important to stress that load adaptive displacement means and the related pressure drop feedback control systems, matte it possible to eliminate the need for any special ( mayor ) energy commutal:lng equipment.
Load adaptive displacement means and the energy regenerating circle.
Returning to Fig.22, let's consider more specifically the load adaptive displacement means 196 of pump 194 and the load adaptive displacement means 130 of pump I20. The examplified schematics of load adaptive displacement means 196 and 130 are presented by figures 23 and 24, respectively.
7'Irese sirnpll f led schematics show (1) swashplates 246 and 266 of the voriable displacement yumps ;
(2) swashplate hydraulic cylinders 242 and 262;
(3) forces Fg2 and Fg~ of the swashplate precompressed springs;
( ~I ) swashplate displacement restrictors 2~Iti and 26a;
(5) swashplate spool valves 250 and 270;
(6) the spool precompressed springs 254 and 2'74 defining command _ signals D P2R and ,G P5 , respectively;

WO 99/64761 ~9 PCT/US98/12200 -('~) tire principal angular positions of swashpl.ates ( "zero"
ang.l.e, regulated angles, maximum angle, and small rtegative angle) .
Figures 23 and 24 are simplified and made similar to the extend possible.
Each swasl~plate is driven~F~y a~plunger o~he related cylinder.
against the force of a precompressed spring. Each hydraulic cvyJ.inc3er is controlled by the related three-way spool va.l ve _wl~ic:l~ J.s also provided with the pressure and tank lJ_nes.
The pressure line is powered by an input pressure PIN which is supplied by any appropriate pressure sourse.
The valve spool is driven by a )rressure drop feedback signal against'the force of the )mec~ornpr essed spring defining the pressure drop command sign~31 .
Ncrt:e that three-way valve can also be repJ.aced by a two-way valve wlr.i.c:lt clcres not trove the tan)c line ( In ''this case the fault J.irur i.s connected through a throutle valve to the.l..i.ne of hydraulic c,yli.nder) .
'l'Ite FiS818ting supply line pressure drop feedbac)c signal 1'2R- j'(~2 i.s alrErl.isd to t)re spool 257. of valve 7_50 ( see Cig . 23 ) to construct ~t:he assisting supply line pressure drop feec9bacl;
c:crntrol system and, thereby, to maintain pressure h2tZ " POl ~ P2R in the outlet line 30 of the assisting consl:artt clisp~.acement motor l9li which is driving the assisting var.fab.le cl:i.sp.kacernent pump 191 (as it was a.l.ready basically explained kre.fore). nt the balance of the assisting supply line pressure drop feec9bac)c control, the spool 7.52 of valve 250 is in the neutral spool position which is shown on rig.23. Note I;ltat ..C~, h2lz~"~ P2 , as it was already indicated before.
Tits exhaust line pressure drop feedback signal t'~5-P5 1s at;yr.l..i_ed I:o the spool 272 of valve 270 (see rig. ~~I ) I;o consl:ruc:t:
t:lte energy recupturing pressure drop feedback control system and.
late .retry, to maintain pressure P5-'-P05-,p p5 irt the exhaust:
.Line L.5 powering the exhaust line constant displacement rnot:or .11.6 which iR driving the exhaust line variable ciiep.kacement;
lnrmp 1.20 ( as i t was already basically explained before ) .
nt ttte balance of the exhaust line pressure drop feedback control., WO 99/64761 g~ PGT/US98/12200 -'I2 the spool 272 of valve 270 i~le neutral spool position which .is shown on ~'ig.2~. Note that pressure drop command signals p p2 ,,p,p2R, and LlpS are selected so that ~ Q5~"~~ F,2~~. ~,p2 , as it is required by expression ( 3),.
t~ig.25 illustrates an examplified energy regenerating circle.
tt is assumed that the wheeled~vehicle is moving in a horizorstal direction only. l~s the vehicle is moving with a constant speed , decelerated, completely stoped, and accelerated, the re.lat;ed energy regenerating circle is completed. This stop-and-go energy regenerating circle has been already briefly introduced before ( to explain the concept of preventing a substantial pressure drop regulation interferrence ) and is easily readable on E'ig.25, when considered in conjuc:tion with figures 7.2 to 2Q and the related text. For example,wl'~ile the vetricle is decelerated, the swashplate 266 is positioned as indicated on t~j.g.24. While the vehicle is accelerated, the swastrp.lr~te ?.~lfi is posit.loned as indicated on rig.23.
ttegenerative drive system having the combined energy accumulating means.
'fhe schematic shOWn On t'ig..t9 i.s now further modified to replace the independent regenerating circuitry by the built-in regenerating circuitry and to improve the utilization of the cornbined energy accumulating means. accordingly, the assisting variable delivery fluid power~supply (motor 118 driving pump .1.1~! ) , the check valves 40 and 49 , and the electrohydraullc energy converting rneans 1~2 are eliminated. 'fhe modified schematic is shown on ~ig.26. The added components are:
h (a) electrical motor-generator 29U, (b) constant displacement motor 300. (c) shut-off valve 298, and (d) check valve 2y6.
The primary engine (motor) 100, the direct-current motor-generator 290, the hydraulic motor 300, and the hydraulic pump 90 are all mechanically connected by a common shaft 98.
'.t'he motor-generator 290 is also electrically connected (through WO 99/64761 g 1 PCT/US98/12200 -lines 292 and 294) with the electrical accumulator 144.
Un the other hand, the hydraulic accumulator 122 is hydraulically connected (through shut-off valve 298) with the inlet line 302 of motor 300.
The regenerative drive system of Fig.26 makes it possible to minimize the required engine size of a wheeled vehicle. The engine 100 is provided with a speed control system which is assumed to be included in block 100 and which is used to maintain a preselected (basic) speed of shaft 98 while allowing some speed fluctuations under the load which is applied to the shaft 98. The related margin of accuracy of the speed control system is actually used to maitain a balance of power on the common shaft 98 and, thereby, to minimize the required engine size of a wheeled vehicle.
The driving'torque of shaft 98 is generally produced by engine 100, by motor-generator 290 (when it is working as a motor), and by motor 300 (when it is powered by the hydraulic accumulator 122 through shut-off valve 298).
'.Che loading torque of shaft 98 is basically provided by pump 90 and by motor-generator 290 (when it is working as a generator).
Note that at some matching speed of shaft 98 (within the margin of accuracy of the speed control system) a speed-dependent voltage of generator 290 is equal to a charge-dependent voltage of accumulator 144, so that no energy is transmitted via lines 292 and 294. As the speed of shaft 98 is slightly reduced, the e.Lectrical energy is transmitted from the electrical accumulator 144 to the electrical motor 290 helping engine 100 to overcome the load. On the other hand, as the speed of shaft 98 is slightly increased, the electrical energy is transmitted from the electrical generator 290 to the electrical accumulator 144 , allowing to utilize the excess power of shaft 98 for recharging the electrical accumulator 144. Note also that shut-off valve 298 is normally closed and is open only under some preconditions - in order to power the constant displacement motor 300 by the hydraulic energy of accumulator 122.

WO 99/64761 g2 PCT/US98/12200 -Let': assume, first, that a wheeled vehicle, such as a city transit bus; is moving in a horizontal direction only.
And .Let's consider briefly the related energy regenerating circle. bus .l. ~~As th~ moving with a constant speed, the pump 90 is basically powered by engine 100.
2. As the bus is decelerated, the mechanical energy of a bus mass is converted to the hydraulic energy of accumulator 122.
The excess energy of accumulator 122 is converted - via valve 29f3, motor 300, and generator 290 - to the electrical energy of accumulator 144. The primary engine 100 may also participate in recharging the electrical accumulator 144.
3. As the bus is stoped, the engine 100 is used only for recharging l:he electrical accumulator 144.
~i . l1s the bus is accelerated, the pump 90 is basicaJ..i.y powered by motor 300 and is also powered by engine 100 and motor 29U. ' The consi,ant displacement rnotor 300 is powered by t:he hydraulic accumulator~lZ2, through shut-off valve 298.
tape t~us is moving up-hill, the pump 90 is driven by engine .t00 arid motor. 29U which is powered by electrical accumulator 144.
As the bus is moving down-hill, the mechanical energy of a bus mass is converted to the hydraulic energy of accumulator 17.2, arrd this I~ydraulic energy is further converted - via valve 2911, motor 300, and generator 290 - to the electrical energy oI
accumu.l.ator 144.
An optional control signal "S" which is applied to the stmt-off valve 29F3, is produced by an optional control unit: which .is riot shown on Fig.26. This control unit can be used Ior controlling such optional functions as follows:
(a) opening shut-off valve 29a - wt~pn the vehicle is accelerated;
( b) opening shut-off valve 29E1 - when the vehicle is rnov.irrg down-hill and after accumulator 122 is substantially charged;
(c) opening shut-off valve 298 - when the vehicle is decelerated, i.n order to convert the excess energy of hydraulic accumulator 122 to the electrical energy of accumulator 141;

WO 99/64761 $3 PCT/US98/12200 -(d) cyenJ.ryl plo,rt;-c,~f vrrtve 7911 ;)uet aCCex ac;aumc.r.lat;vr J.)2 l.rc w,c.rlrrri:trrri:.ltr.i..t.)~ rtrsrgetl.
,. . ... , ! !: nl~acl.lcl bA Rln1)Irr~r~.i.yed l:tml: scammt~tJ.c: of i'iE,). 2fi ig v.C
t~ ver. y ~teuecw.l. nnt:vtw. '.llw exmnp.t.i..t.lvd mc~d.t.C.tc~r~t.J.vntl vJ: (:Irid racarernrrl:.i.c c:arr 1»a t~r.lefly carr~xac:(:er. i.~.ed c~r~ fvll.owr~:
(a) the constant'~dispJ.acement motor 300 is~of a smaller flow capacity in comparison with the-variable displacement.pump 90~.
the variable displacement pump 90 is also used as a motor to provide an aJ.ternative route for transmission of energy from accumulator 122 to the common shaft 98;
(c) providing at least two preselectable (basic) speeds of shaft 9F3 to respond to the changing load invironments;
(d) modifying the hybrid motor means driving pump 90 - as it is explained at the end bf this description.
Two basic types of res~enerative systems.
x'here are basically two types of regenerative adaptive fluid motor control. systems: (a) the regenerative system havJng an inc9ependent regenerating circuitry ( see J.'igures .ll to 72 ) and (b) the regenerative system having a built-in energy .regenerating circuitry (see figures 9, 10, and 26).
fhe first type oC regenerative systems .is identified by that the primary and assisting supply line pressure drop teedbac)t control systems are separated. 'rhe second type of regenerative systems is identified by that the primary and assisting supply .line pressure drop feedback coritroJ systems are not separated and are represented by only one supply~line pressure drop feedback control system. The generalized first-type systems have been already introduced by figures 1:1, 1~, and 15. A generalized second-type system is shown on f'ig.27, which is mostly self-explanatory and is still further understood when~compaired wii:h figures 9, 10, 26, and 15.

WO 99/64761 g4 PCT/US98/12200 -Note that transition from the first to the second type of regenerative systems is accomplished typically by replacing the separated primary and assisting supply line pressure drop feedback control systems by only one supply line pressure drop feedback control system and by implementing the primary power supply means for powering the energy accumulating means. For example, in the regenerative system of Fig.22, the transition from the independent regenerating circuitry to the built-in regenerating circuitry can be accomplished by eliminating the separated primary supply line pressure drop feedback control system and by implementing the primary pump 90 for , powering the hydraulic accumulator I22 ( the resulted schematic can be still further modified to incorporate also an electrical accumulator ) . - --The two basic types of~regenerat3ve systems can generally be combined to include both - the built-in regenerating circuitry and the independent regenerating circuitry. ' For example, in the regenerative system of Fig.26, the transition to the combined schematic can be accomplished by adding an~assisting supply line pressure drop feedback control system,which is shown on Fig.22 and whl.ch includes the constant displacement motor 198 driving the variable displacement pump I94.
The resulted combined schematic is also applicable to the wheeled vehicles.
- .____ ...._ ......_. __.. .._~. , nd~tpL.lve 1'luld c:uttl.l:v.l aartcJ I,ItH load envl~,vrtmenl.s (~ mulpcwl.:c~rul l:itr..tC I,It.l.n Lnvettl.i.ort ~n nvl: .l:lm.i.l.e~d t~.o arty prrrl~.l.c:nl.,~t: ayrpl..ir_:~I:iW r. IC i..s Lo r3~ty l.lrttl. J.'lguret9 .L. ~a. 9.
~mrcl 1 1, sj rc~ nc~(. re.l ~ U.c~c! cm ( y l.o llte I~yd!~tiu.l..l.c:
tWetagc~e . I ~ .ll.t ,~.l.sc~ i.m R~ty tltttl. ) lt~tarn~t I(). ~.L.I . .1G tv 22. urtcl aG ttre trcrl rcrl.~,l.cml crn i y t,cr I:hrc~ mcl:c~r velr.l.c~ latt . 1 n .Cttc~t: , l.lie l yp.l.t:u.l. tul,~pl J ve WO 99/64761 gs PCT/US9$/12200 -;::c~irema L.irs which are shown on f a cures 1, A , G , 9 to .t 2 , 16 to ?2, ,arrd l& are exlras:ively 3ssocial:ed only with :~ type of. rnof:or toad vt tt>.e .fluid motor .t (or .tSU), as it fs characterized below:
( a 1 r he s.herna t i cs. shown on f figures 1, 4 , ~ 9 , and 12 a r a ..-~dallve to the one -d~rectional..static load force:
(b) the schematics shown on figures 10, 11, 16 to 22, and 2f, ~3rr adaptive to the two-directional dynamic .Loac9 force, wlric,lr a.s generated during . aocel.eration-and deceleration .of ~. a -load mass moving only in one direction.r (e) the schematic shown on Pig.6,ib adaptive to the two-directional statio load foreee.
simplified Tha ibovr, ,loci-related claasificatiorr of typioa.l adaptive schematics is instrumental in Modifying these achematica for tho modified load environments.
For example.' the schematic shown.on Pig.lB is adaptj.ve tc the two-directional dynamic loac! force, which is generated during acceleration and deceleration of a load mass moving ~r.'_;;
in one diz~ection. Il 'the load environments are modifis~! c~:
replacing this two-directional dynamic load force by the one-directional static load force, the schematic of Fig.;.
must be also modified. The modified schematic may inc~::d~
t;he five-way spool valve 2 instead of the four-way spool valve z which is shown~.on Fig.lB. . In this case, the energy regenerating c~'_rcuitry using hydraulic accumulator L22 must be sw3.tched over from the exhaus ~ .,-.c~xor i:.ne LS to the exhaust power line L3. as i~ is illus=raT:~
by Fig.l2 - for a case of using the fl.yiwheel accumulate- Q~.
Adaptive fluid control with a.supplementarv output motor.
There is one special modification of independent regenerating circuitry which is not covered by the generalized schematic of Fig. l5 and Which, therefore, is considered below.
The regenerative braking pump 170 of Fig.21 can also be used as WO 99/64761 g6 PCT/US98/12200 -a variable displacement motor to make-up a supplementary variable displacement motor/pump. The pump functions of this supplementary output motor/pump have been already studied with the help of Fig.2l. For stmplicity, the motor functions of thi::z supplementary output motor/pump will also be studied separately.
t~ig.2f3 is derived from Fig.21 by replacing the supplementary output pump 170 by the supplementary output motor 170 and by eliminating the assisting supply line pressure drop feedback con trol system (including motor 114 and pump lia ) and some other components (check valves 40, 44, and 174). The variable.
displacement motor 170 is powered by the hydraulic accumulator 122 through a shut.-of f valve 297 which is basically controlled ' ~ by pressure signal P02. while this pressure signal is comparatively small, the shut-off valve 297 is closed. As signal P02 is further raising-up,, the shut-off valve 297 is open, provided that there is t3ti11 enough energy stored in the hydraulic accumulator 122.
'flte v~triflbie disp:l.acemenl; means 99 o.f motor 170 are constructed -I:o nmlre-up ~t clisitlaoemerni; feedback ~ conl;rol sys I;ern ittcJ.ud.trtg .
s variavle d3.shl.acemeni; meoltartism (of motor 170) and emp:Lvyi.ng :a displ.ac:emerrt; .feectback aowl:rol arrow ~ignRl Ad. ~Ult.ts~p~Wst.l. .ls ger»rrttec3 in aoeordanoe wi~t;lt a dlfferenoe be~l;ween s commend-displrtoemewl; signal do - C~ P02 ( where C1~ is ~..t consi;>ZwL coei'fi.ciewl; ) end s meoitRntsm displacemenU; ( feedhaclc s igtts3l ) dl of vhe variable displ.aoemerri; meehartisrn of motor 170.
A pressure-displaoemerrl: i:rartsduoer oonver~l;i.rtg the pressure sign~..tl t~02 1-t~~o ~I;lve propori;ional command-displacemerni; signal do=Ch' P02 is l.neluded l.wl;o ~I;he varis~ble c~j.splaoemerrt means 99 of motor 1'70.
'1'It.ls I; rensdtacer mrty irtoorporR-te, i'or example, a small sht-ing-l.oeclect hydrauti~e oy7.inder aoi:ua~l:ed by i;lte pressure signal r02 - 'flte dis')Jlacetnewt i'eedback cottLrol arrow signal. ltd - do- d1 i.s intpleuteta~ed for modula'Ling ~I;Ite varl.a.i~a.e cilePl.acemenl; meoltsnlsm o.f motor 170 , for reguJ.al;ing is mech>3ttisnt displacement; dl of vhe variable dispa.acemetrl;

WO 99/64761 g~ PCT/US98/12200 -motor mechanism of'~ 1?0 in accordance with 'the command signal do ( and hence ; in accordance with 'the pressure rate p02 '- do~~p in the motor line L2 ) .
tt should ~ be empi~asizedthat ~tl~e displacement feedbattc control system, which is well Icnown. in the art, is, in fact, the position feedback control system and that, therefore, the general position feedback control technique, which is characterised above with respect t o the fluid motor position feedbac k control system, is also basically applicable to the displacetnent feedback cotrtrol system.
T» general, the displacement feedback control cir cuitry of motor 170 is ad,~usted so that, while the pressure Pp2 in 'the motor J_ine L1 is comparat3.ve).y low, this circuitry is not operative and dl~' 0. , As the pressure P02 in i;l~e motor line ),1 is .further ra3.sing-up, ~tl~e displacement dl of motor 170 is 3.ncreasing~ acdvrdingly, so 'that ~tl~e total accelerating torque is properly distributed between the fluid motor 1 and the supplemeritar_y. motor 170.-._ The -use of -motor. 170 makes it possible to substantially increase the available (total) accelerating torque of the wheeled vehicle.
Note that the use of motor 170 on small displacements should be avoided for as much as possible. Note also that a significant dynamic performance superiority must be provided for the displacement feedback control system against the primary supply line pressure drop feedback control system, in order to prevent their substantial dynamic operation interference. The concept of providing "a significant dynamic performance superiority" have been already generally introduced before and is further readily applicable to the displacement feedback control system versus the primary supply line pressure drop feedback control system.
The related generalized schematic of Fig.29 is derived from Fig.l5, is mostly self-explanatory, and is reflective of the facts that the assisting supply line pressure drop feedback WO 99/64761 g8 PCT/US98/1ZZ00 -control system is now elimi.nated~ and that pressure Pac from the hydraulic accumulator 122 is now applied to the supplementary output motor 170 of the fluid motor and load means.

WO 99/64761 g9 PGT/US98f12200 -Some other related considerations.
The schematic of Fig.26 can be modified by changing the hybrid motor means driving pump 90. The exemplified modifications are as follows.
1, The electrical motor-generator 290 and the related electrical accumulator 144 are exluded from this schematic. , The constant displacement motor 300 is replaced by a variable displacement motor which is used to construct a supplementary shaft-speed feedback control system maintaining the preinstalled speed of shaft 98 when this variable displacement motor is powered by accumulator 122. As a result, the hydraulic energy of accumulator 122 is transmitted to shaft 98 in accordance with the actual energy requirenment. Note that possible interference between the main shaft-speed feedback control system ( of primary engine 100 ) and the supplementary shaft-speed feedback control system ( of the variable displacement motor ) is prevented by providing VCS = VCM ~"' OV
where:
vCM - is a velocity command-signal for the main shaft-speed feedback control system, VCS - is a velocity command-signal for the supplementary shaft-speed feedback control system, and QV - is a sufficient velocity margin between these two systems.
In other words, the supplementary speed control system should actually be regulated just "slightly above" the main speed control system.
2. The primary engine 100 is excluded from the schematic of WO 99/64761 9~ PCT/US98/12200 -Fig.26. In this case, the primary energy should be supplied by the electrical accumulator 144.
3. The primary engine 100 is disconnected from shaft 98 and is driving a constant displacement pump which is powering the constant displacement motor 300. In this case, the hydraulic energy of accumulator 122 is transmitted to shaft 98 via this constant displacement pump driving the constant displacement motor 300.
The schematic of Fig.22 can be modified by providing the primary engine 100 with a variable-speed feedback control system which is used for maintaining the engine maximum energy efficiency.
Note that as the engine speed increases, the displacement of pump 90 is being reduced accordingly, to maintain the pump flow output,which is defined only by the opening of valve 2.
The schematic of Fig.22 can also be modified by eliminating the primary . supply line pressure. drop -feedback control___system __ like it is ) and by implementing the primary pump 90 for powering the hydraulic accumulator 122. The resulted schematic having a built-in energy regenerating circuitry can also be constructed for maintaining the engine maximum energy efficiency.
_ _ _ __ _ __ ___ .._._- _- _.---It should be emphasized that adapti.vP fluid control schematics t~eine~ con:;i.dered are the concept ilJ.ustrating schpmal:i.r_g onJ.Y.
Some design related considerations are as follows.
.t . '.t'he maximum and minimum prer3r3ures in any f luld power line must: be restricted,.
2 . vt~hP primary supply power line 54 ( see f figures t.l tv 2.7 ) can be protected by I:Ire maximum pressure reJ.J.ef valve.
'1.'he maximum pre:3aure in line 5~1 can also be restricted by using the-variable delivery means 93 of pump 90.
In general, t:he maximum pressure relief valves can also be uRed t:o protect other hydraulic lines.
3 , 'i'!re check valve 159 ( f figures 2t) and 22 ) is added ~to very etficient:l.y restrict the maximum pressure in the exhaust rnotor .Line L~~1 by relieving an exces3rr fluid from l:his line ( t:hrougtr checac valvA 15~t ) into the higtr-pressure hydraulic ..
acc:umul.ator 122.
Sim.tlar to point 3, the checlc va.l.ves can be used tv rest:ri.ct the mt~xirnum preesure i.m sti.l.l of:her power limes.
'.Che chpclc va l ve 15b ( figures 7.0 and 22 ) is added to effecti.ve.l.y restrict the minimum pressure in the supp.ty motor l:i.rre t.~l. by connecting this line (.through check valve 155) with tire tunic 62. ~ ' f,, S.tmt.tar to point 5, the check valves can be used to rest:ri.ct: the minimum pressure in still other power lines.
I~vr.~ ext'rrntri.e, t:he eXhaust power line l.5 (or L3) r~trould usually Lie ronrrected through a check va.Lve to the tunic tv avoid creating a vacuum in this line.
7 , ',tire oil tank capacity can of ten be reduced, tire oil cvoli.ng system cam often be e.l.iminated.
(; . '.fire vi..L tunic 6~ can of ten be replacec9 by a l.vw-presser. a lrydrau.tic accunru.Lat:or (accornpamied by a smat.l-srrptrl.empntary tunic ) . . -_-.. _..~
9, The oil~.tank 62. can .also be supplemented by a low-pressure centrifugal pump.

How to restrict a supply line power rate.
Still other engineering consideration on a way of transition from the concept illustrating schematics to the practical design of regenerative adaptive fluid motor control systems is how to restrict the supply line power rate - when it is needed.
Let's consider, for example, the schematic of Fig.26 - as it is applied to the motor vehicles. In this case, the required supply line power rate in line L2 is defined by the load 96 of motor 1 and by the opening of valve 2 and can generally exceed the combined power supply capacity of engine 100 and electrical motor 290. To prevent this overload event from happening.
the practical design must include the means of restricting the spool displacement (SD) of valve 2 versus the load pressure rate (LP) in line L1 ( or in line L2 ), so that the resulted load power rate ( which is proportional to LP x SD ) would not exceed the limited power supply capacity.
In other words, the practical regenerative adaptive fluid motor control systems may include the means of restricting the required load power rate in accordance with the limited power supply capacity.

Re eneraxive ada tive fluid control versus Non regenerative adaptive fluid control.
As it was already mentioned before, there are basically two types of the two-way load adaptive fluid motor control systems.
The non-regenerative adaptive fluid motor control systems are equipped with an exhaust line pressure drop feedback control system including an exhaust.line pressure drop regulator.
On the other hand, the regenerative adaptive fluid motor control systems are equipped with an,energy recuperating pressure drop feedback control system including an exhaust line energy recuperating means.
The above description is presented in a way of transition from the non-regenerative adaptive fluid motor control to the regenerative adaptive fluid motor control. Note that the resulted regenerative adaptive fluid control schematics being considered are, in fact, convertable. The transition from these schematics back to the non-regenerative adaptive fluid control can generally be accomplished by replacing the energy recuperating pressure drop feedback control system ( and the related energy regenerating circuitry ) by the exhaust line pressure drop feedback control system including the exhaust line pressure drop regulator.
While my above description contains many specificities, those should not be construed as limitations on the scope of the invention, but rather d.s d.n examplifica.tion of some preferred embodiments thereof. Many other va.riationa are possible. For example, the schematic shown on Fi~.4 can be easily modified to convert the five-way valve 2 to the six-wa.y valve by separating the supply power line L6 from the . supply power line I~2 . The separated line L6 ca.n be then connected directly to the line 54 of the additional hydraulic power supply 50 shown on Fig.2.
Various modifications and variations, which basically rely on the te=~chings through which this disclosure hds advanced the H.rt, are properly considered witnin the scope of this invention a.s defined by the appended claims and their legal equivalents.

Claims

Claims to "Regenerative adaptive fluid control:' What is claimed is:
1. A .regenerative adaptive fluid motor control method comprising the steps of :
constructing a fluid motor control system including fluid motor and load means, spool valve means, and fluid power means:
said fluid motor and load means including fluid motor means and motor load means and accumulating a load related energy:
said spool valve means having, at least three fluid power lines including a motor line. conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said fluid motor and load means, a supply power line, and an exhaust power line;
said fluid power means including a primary variable delivery fluid power supply generating a primary pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
introducing an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said load related energy of said fluid motor and load means;

constructing an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means;
regulating an exhaust fluid pressure drop across said spool valve means by said energy recuperating pressure drop feedback control system by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;
constructing a load adaptive energy regenerative system including first load adaptive energy converting means, energy accumulating means, and second load adaptive energy converting means;
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system;
providing a load adaptive regeneration of said load related energy of said fluid motor and load means by said load adaptive energy regenerating system by converting said load related energy through said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system to a recuperated energy of said energy accumulating means, by storing said recuperated energy by said energy accumulating means, and by converting said recuperated energy through said second load adaptive energy converting means to a regenerated energy reusable by said fluid motor and load means;

facilitating said load adaptive regeneration of said load related energy of said fluid motor and load means by regulating said exhaust fluid pressure drop across said spool valve means by said energy recuperating pressure drop feedback control systems;
constructing a primary supply line pressure drop feedback control system including said primary variable delivery fluid power supply;
regulating a primary supply fluid pressure drop across said spool valve means by said primary supply line pressure drop feeback control system by varying a primary pressure rate of said primary pressurized fluid stream by a primary variable delivery means of said primary variable delivery fluid power supply.

2. The method according to claim 1 wherein said exhaust line energy recuperating means includes an exhaust line variable displacement motor being powered by said exhaust power line, and wherein varying said counterpressure rate in said exhaust power line is accomplished by an exhaust line variable displacement means of said exhaust line variable displacement motor.
3. The method according to claim 1 , wherein said exhaust line energy recuperating means includes an exhaust line fluid motor being powered by said exhaust power line and driving an exhaust line variable displacement pump, and wherein varying said counterpressure rate in said exhaust power line is accomplished by an exhaust line variable displacement means of said exhaust line variable displacement pump.
4. The method according to claim 1 , wherein said fluid motor means include at least one hydraulic cylinder having at least one loadable chamber, and wherein said load related energy of said fluid motor and load means includes a compressed fluid energy of said loadable chamber of said hydraulic cylinder.

5. The method according to claim 1 , wherein' said motor load means include a frame of a hydraulic press.
wherein said fluid motor means include at least one hydraulic cylinder of said hydraulic press, wherein said hydraulic cylinder includes a loadable chamber being loaded against said frame of said hydraulic press, and wherein said load related energy of said fluid motor and load means includes a compressed fluid energy of said loadable chamber of said hydraulic cylinder of said hydraulic press.
6. The method according to claim 1 , wherein said motor load means include a mass load of said fluid motor means, and wherein said load related energy of said fluid motor and load means includes a mechanical energy of a mass of said mass load.
7. The method according to claim 1 , wherein said motor load means include a mass of a wheeled vehicle, wherein said fluid motor means are loaded by said mass of said wheeled vehicle, and wherein said load related energy of said fluid motor and load means includes a mechanical energy of said mass of said wheeled vehicle.

The method according to claim 1 , wherein said primary variable delivery fluid power supply includes a primary variable displacement pump generating said primary pressurized fluid stream, and wherein varying said primary pressure rate of said primary pressurized fluid stream is accomplished by a. primary variable displacement means of said primary variable displacement pump.
9. The method according to claim 1 , wherein said primary variable delivery fluid power supply includes a primary variable speed motor driving a primary fluid pump generating said primary pressurized fluid stream, and wherein varying said primary pressure rate of said primary pressurized fluid stream is accomplished by said primary variable speed motor.

10. The method according to claim 1 , wherein said energy accumulating means are implemented for powering an assisting variable delivery fluid power supply generating an assisting pressurized fluid stream being implemented for powering said fluid motor means through said spool valve means.
wherein said second load adaptive energy converting means include an assisting supply line pressure drop feedback control system containing said assisting variable delivery fluid power supply and regulating assisting supply fluid pressure drop across said spool valve means by varying an assisting pressure rate of said assisting pressurized fluid stream by an assisting variable delivery means of said assisting variable delivery fluid power supply, and wherein said method further comprising:
accommodating said load adaptive regeneration of said load related energy of said fluid motor and load means by correlating said primary pressure rate of said primary pressurized fluid stream with said assisting pressure rate of said assisting pressurized fluid stream by regulating said primary supply fluid pressure drop across said spool valve means and regulating said assisting supply fluid pressure drop across said spool valve means by said primary supply line pressure drop feedback control system and said assisting supply line pressure drop feedback control system, respectively.

11. The method according to claim 10 wherein said energy accumulating means include a flywheel, wherein said assisting variable delivery fluid power supply includes an assisting variable displacement pump being driven by said flywheel and generating said assisting pressurized fluid stream, and wherein varying said assisting pressure rate of said assisting pressurized fluid stream is accomplished by an assisting variable displacement means of said assisting variable displacement pump.
12. The method according to claim 10 , wherein said energy accumulating means include a hydraulic accumulator, wherein said assisting variable delivery fluid power supply includes an assisting fluid motor being powered by said hydraulic accumulator and driving an assisting variable displacement pump;
wherein said assisting pressurized fluid stream is represented by an exhaust from said assisting fluid motor, and wherein varying said assisting pressure rate of said assisting pressurized fluid stream is accomplished by an assisting variable displacement means of said assisting variable displacement pump.

13. The method according to claim 10 , wherein said energy accumulating means include a hydraulic accumulator, wherein said assisting variable delivery fluid power supply includes an assisting variable displacement motor being powered by said hydraulic accumulator and driving an assisting fluid pump generating said assisting pressurized fluid stream, and wherein varying said assisting pressure rate of said assisting pressurized fluid stream is accomplished by an assisting variable displacement means of said assisting variable displacement motor.
14. The method according to claim 1 wherein said fluid motor means include a variable displacement motor, and wherein said method further comprising:
constructing a displacement feedback control system including a variable displacement mechanism of said variable displacement motor;
regulating a mechanism displacement of said variable displacement mechanism of said variable displacement motor by said displacement feedback control system at least approximately in accordance with a mechanism displacement command signal being correlated with a spool displacement signal of said spool valve means.

15. The method according to claim 1 further comprising :
constructing a fluid motor output feedback control system including said fluid motor control system and having output feedback control means measuring a motor output of said fluid motor means and producing an output feedback control error signal;
regulating said motor output of said fluid motor means by said fluid motor output feedback control system by modulating said spool valve means by said output feedback control error signal ;
preventing a substantially dynamic operation interference between regulating said exhaust fluid pressure drop and regulating said motor output by providing a significant dynamic performance superiority for said energy recuperating pressure drop feedback control system against said fluid motor output feedback control system by providing either a significant frequency-response superiority or a significant final-transient-time superiority for said energy recuperating pressure drop feedback control, system against said fluid motor output feedback control system;

preventing a substantial dynamic operation interference between regulating said primary supply fluid pressure drop and regulating said motor output by prodding a significant dynamic performance superiority for said primary supply line pressure drop feedback control system against said fluid motor output feedback control system by providing either a significant frequency-response superiority or a significant final-transient-time superiority for said primary supply line pressure drop feedback control system against said fluid motor output feedback control system.
16. The method according to claim 15 , Wherein said fluid motor output feedback control system is represented by a fluid motor position feedback control system.
wherein said output feedback control means are represented by position feedback control means, wherein said motor output is represented by a motor position, and wherein said output feedback control error signal represented by a position feedback control error signal.

17. A regenerative adaptive fluid motor control system comprising:
a fluid motor control system including fluid motor and load means, spool valve means, and fluid power means;
said fluid motor and load means including fluid motor means and motor load means and accumulating a load related energy;
said spool valve means having, at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said fluid motor and load means, a supply power line, and an exhaust power line;
said fluid power means including a primary variable delivery fluid power supply generating a primary pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
an exhaust line energy recuperating means for varying g counterpressure rate in said exhaust power line end for recuperating said load related energy of said fluid motor and load means;

an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate an exhaust fluid pressure drop across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;
a load adaptive energy regenerating system including first load adaptive energy converting means, energy accumulating means, and second load adaptive energy converting means;
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said load related energy of said fluid motor and load means to a recuperated energy of said energy accumulating means for storing and subsequent use of said recuperated energy;
said second load adaptive energy converting means operable to convert said recuperated energy of said energy accumulating means to a regenerated energy reusable by said fluid motor and load means;
a primary supply line pressure drop feedback control system including said primary variable delivery fluid power supply and operable to regulate a primary supply fluid pressure drop across said spool valve means by varying primary pressure rate of said primary pressurized fluid stream by a primary variable delivery means of said primary variable delivery fluid power supply:

18. The system according to claim 17 , wherein said energy accumulating means are implemented for powering an assisting variable delivery fluid power supply generating an assisting pressurized fluid stream being implemented for powering said fluid motor means through said spool valve means, and wherein said second load adaptive energy converting means include an assisting supply line pressure drop feedback control system containing said assisting variable delivery fluid power supply and operable to regulate an assisting supply fluid pressure drop across said spool valve means by varying an assisting pressure rate of said assisting pressurized fluid stream by an assisting variable delivery means of said assisting variable delivery fluid power supply, 19. A regenerative adaptive fluid motor control method comprising the steps of :
constructing a fluid motor control system including fluid motor and load means, spool valve means, and fluid power means ;
said fluid motor and load means including fluid motor means and motor load means and accumulating a load related energy:
said spool valve means having, at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said fluid motor and load means, a supply power line, and an exhaust power line;
said fluid power means including energy accumulating means being implemented for powering a variable delivery fluid power supply generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means;

introducing an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said load related energy of said fluid motor and load means;
constructing an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means;
regulating an exhaust fluid pressure drop across said spool valve means by said energy recuperating pressure drop feedback control system by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;
constructing a supply line pressure drop feedback control system including said variable delivery fluid power supply;
regulating a supply fluid pressure drop across said spool valve means by said supply line pressure drop feedback control system by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
constructing a load adaptive energy regenerating system including first load adaptive energy converting means, said energy accumulating means, and second load adaptive energy converting means;
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system;
said second load adaptive energy converting means including said supply line pressure drop feedback control system;

providing a load adaptive regeneration of said load related energy of said fluid motor. and load means by said load adaptive energy regenerating system by converting said load related energy through said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system to a recuperated energy of said energy accumulating means, by storing said recuperated energy by said energy accumulating means, and by converting said recuperated energy through said second load adaptive energy converting means including said supply line pressure drop feedback control system to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
facilitating said load adaptive regeneration of said load related energy of said fluid motor and load means by regulating said exhaust fluid pressure drop across said spool valve means and regulating said supply fluid pressure drop across said spool valve means by said energy recuperating pressure drop feedback control system and said supply line pressure drop feedback control system, respectively.

20. The method according to claim 19, wherein said fluid power means include a primary power supply being implemented for powering said variable delivery fluid power supply, and wherein a primary energy of said pressurized fluid stream is supplied by said primary power supply through said variable delivery fluid power supply, 21. The method according to claim 19 , wherein said fluid power means include a primary power supply being implemented for powering said energy-accumulating means, and wherein a primary energy of said pressuried fluid stream is supplied by said primary power supply through said energy accumulating means.

22. The method according to claim 19 , wherein said exhaust line energy recuperating means includes an exhaust line variable displacement motor being powered by said exhaust power line, and wherein varying said counterpressure rate in said exhaust power line is accomplished by an exhaust line variable displacement means of said exhaust line variable displacement motor.
23. The method according to claim 19 wherein said exhaust line energy recuperating means includes are exhaust line fluid motor being powered by said exhaust power line and driving exhaust line variable displacement pump, and wherein varying said counterpressure rate in said exhaust power line is accomplished by an exhaust line variable displacement means of said exhaust line variable displacement pump.
24. The method according to claim 19 , wherein said fluid motor means include at least one hydraulic cylinder having at least one loadable chamber, and wherein said load related energy of said fluid motor and load means includes a compressed fluid energy of said loadable chamber of said hydraulic cylinder.

25. The method according to claim 19, wherein said motor load means include a frame of a hydraulic press, wherein said fluid motor means include at least one hydraulic cylinder of said hydraulic press, wherein said hydraulic cylinder includes a loadable chamber being loaded against said frame of said hydraulic press, and wherein said load related energy of said fluid motor and load means includes a compressed fluid energy of said loadable chamber of said hydraulic cylinder of said hydraulic press.
26. The method according to claim 19, wherein said motor load means include a mass load of said fluid motor means, and wherein said load related energy of said fluid motor and load means includes a mechanical energy of a mass of said mass load.
27. The method according to claim 19, wherein said motor load means include a mass of a wheeled vehicle, wherein said fluid motor means are loaded by said mass of said wheeled vehicle.
and wherein said load related energy of said fluid motor and load means includes a mechanical energy of said mass of said wheeled vehicle.

28. The method according to claim 19, wherein said energy accumulating means include a flywheel, wherein said variable delivery fluid power supply includes a variable displacement pump being driven by said flywheel and generating, said pressurized fluid stream, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.
29. The method according to claim 19, wherein said energy accumulating means include a hydraulic accumulator.
wherein said variable delivery fluid power supply includes a fluid motor being powered by said hydraulic accumulator and driving a variable displacement pump, wherein said pressurized fluid stream is represented by an exhaust from said fluid motor, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.

33. The method according to claim 19 , wherein said energy accumulating means include a hydraulic accumulator, wherein said variable delivery fluid power supply includes a variable displacement motor being powered by said hydraulic accumulator and driving a fluid pump generating said pressurized fluid stream, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement motor.

31. The method according to claim 19 , Wherein said variable delivery fluid power supply includes a variable displacement pump generating said pressurized fluid stream, wherein said fluid power means include a primary motor being implemented for driving said variable displacement pump.
wherein said energy accumulating means are implemented for powering said variable displacement pump, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.
32. The method according to claim 19 , wherein said variable delivery fluid power supply includes a variable displacement pump generating said pressurized fluid stream, wherein said variable displacement pump is driven by hybrid motor means including an energy regenerating fluid motor, wherein said energy accumulating means include fluid energy accumulating means being implemented for powering said energy regenerating fluid motor, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.

33. The method according to claim 19 , wherein said variable delivery fluid power supply includes a variable displacement pump generating said pressurized fluid stream, wherein said variable displacement pump is driven by an electrical motor, wherein said energy accumulating means include fluid energy accumulating means being implemented for powering electrical energy accumulating means being implemented for powering said electrical motor, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.
34. The method according to claim 19 wherein said fluid motor means include a variable displacement motor.
and wherein said method further comprising:
constructing a displacement feedback control system including a variable displacement mechanism of said variable displacement motor;
regulating a mechanism displacement of said variable displacement mechanism of said variable displacement motor by said displacement feedback control system at least approximately in accordance with a mechanism displacement command signal being correlated with a spool displacement signal of said spool valve means.

35. The method according to claim 19 further comprising :
constructing a fluid motor output feedback control system including said fluid motor control system and having output feedback control means measuring a motor output of said fluid motor means and producing an output feedback control error signal;
regulating said motor output of said fluid motor means by said fluid motor output feedback control system by modulating said spool valve means by said output feedback control error signal;
preventing a substantial dynamic operation interference between regulating said exhaust fluid pressure drop and regulating said motor output by providing a significant dynamic performance superiority for said energy recuperating pressure drop feedback control system against said fluid motor output feedback control system by providing either a significant frequency-response superiority or a significant final-transient-time superiority for said energy recuperating pressure drop feedback control system against said fluid motor output feedback control system;

preventing a substantial dynamic operation interference between regulating said supply fluid pressure drop and regulating said motor output by providing a significant dynamic performance superiority for said supply line pressure drop feedback control system against said fluid motor output feedback control system by providing either a significant frequency-response superiority or a significant final-transient-time superiority for said supply line pressure drop feedback control system against said fluid motor output feedback control system, 36. The method according to claim 35, wherein said fluid motor output feedback control system is represented by a fluid motor position feedback control system, wherein said output feedback control means are represented by position feedback control means, wherein said motor output is represented by a motor position, and wherein said output feedback control error signal is represented by a position feedback control error signal.

37. A regenerative adaptive fluid motor control system comprising, a fluid motor control system including fluid motor and load means, spool salve means, and fluid power means;
said fluid motor and load means including fluid motor means and motor load means and accumulating a load related energy:
said spool valve means having at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said fluid motor and load means, a supply power line, and an exhaust power line;
said fluid power means including energy accumulating means being implemented for powering a variable delivery fluid power supply generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said load related energy of said fluid motor and load means;
an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate an exhaust fluid pressure drop across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means:

a supply line pressure drop feedback control system including said variable delivery fluid power supply ring operable to regulate a supply fluid pressure drop across said spool valve means by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
a load adaptive energy regenerating system including first load adaptive energy converting means, said energy accumulating means, and second load adoptive energy converting means;
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said load relates energy od said fluid motor and load means to a recuperated energy of said energy accumulating means for storing and subsequent use of said recuperated energy;
said second load adaptive energy converting means including said supply line pressure drop feedback control system and operable to convert said recuperated energy of said energy accumulating means to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means, 38, A regenerative adaptive fluid power transmission in a regenerative adaptive fluid motor control system containing a fluid motor control system including fluid motor means, spool salve means;
and fluid power means;
said spool valve means having at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means, a supply power line conducting a supply fluid flow from said fluid power means and an exhaust power line conducting an exhaust fluid flow to said fluid power means;
said regenerative adaptive fluid power transmission comprising:
an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating an exhaust fluid energy of said exhaust fluid flow;
an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate an exhaust fluid preassure drop across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;
a variable delivery fluid power supply being powered by energy accumulating means and generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means;

a supply line pressure drop feedback control system including said variable delivery fluid power supply and operable to regulate a supply fluid pressure drop across said spool valve means by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
a load adaptive energy regenerating system including first load adaptive energy converting means, said energy accumulating means, and second load adaptive energy converting means:
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said exhaust fluid energy of said exhaust fluid flow to a recuperated energy of said energy accumulating means for storing and subsequent use of said recuperated energy:
said second load adaptive energy converting means including said supply line pressure drop feedback control system and operable to convert said recuperated energy of said energy accumulating means. to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means.

39. A regenerative adaptive vehicle drive system comprising:
a fluid motor control system including fluid motor and load means, spool valve means and fluid power means;
said fluid motor and load means including fluid motor means and a mass of a wheeled vehicle and accumulating a mechanical energy of said mass of said wheeled vehicle:
said spool valve means having at least four fluid power lines including a first a motor line conducting a motor fluid flow to said fluid motor means, a second motor line conducting a motor fluid flow from said fluid motor means, a supply power line, and an exhaust power line;
said fluid power means including energy accumulating means being implemented for powering a variable delivery fluid power supply generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said mechanical energy of said mass of said wheeled vehicle:
an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate en exhaust fluid pressure drop.
across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;

a supply line pressure drop feedback control system including said variable delivery fluid power supply and operable to regulate a supply fluid pressure strop across said spool valve means by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
a load adaptive energy regenerating system including first load adaptive energy converting means, said energy accumulating means, and second load adaptive energy converting means;
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said mechanical energy of said mass of said wheeled vehicle to a recuperated energy of said energy accumulating means for storing and subsequent use of said recuperated energy;
said second load adaptive energy converting means including said supply line pressure drop feedback control system and operable to convert said recuperated energy of said energy accumulating means to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means, 40. The drive system according, to claim 39 wherein said variable delivery fluid power supply includes a variable displacement pump generating said pressurized fluid stream, wherein said fluid power means include a primary engine being implemented for driving said variable displacement pump, wherein said energy accumulating means are implemented for powering said variable displacement pump, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.

41. The drive system according to claim 39, wherein said variable delivery fluid power supply includes a variable displacement pump generating said pressurized fluid stream, wherein said variable displacement pump is driven by hybrid motor means including an engine, an energy regenerating fluid motor, and an electrical motor, wherein said energy accumulating means include fluid energy accumulating means being implemented for powering electrical energy accumulating means, wherein said fluid energy accumulating means are implemented for powering said energy regenerating fluid motor, wherein said electrical energy accumulating means are implemented for powering said electrical motor, and wherein varying said pressure rate of said pressurized fluid stream is accomplished by a variable displacement means of said variable displacement pump.

42. The drive system according to claim 39 , wherein said fluid motor means include a variable displacement motor.
and wherein said drive system further comprising:
a displacement feedback control system including a variable displacement mechanism of said variable displacement motor and operable to regulate a mechanism displacement of said variable displacement mechanism at least approximately in accordance with a mechanism displacement command signal being correlated with a spool displacement signal of said spool valve means.

43. The drive system according to claim 39 , wherein said energy accumulating means include a hydraulic accumulator.
and wherein said drive system further comprising, a recuperative braking variable displacement pump recuperating said mechanical energy of said mass of said wheeled vehicle and being implemented for powering said hydraulic accumulators a displacement control system including a variable displacement mechanism of said recuperative braking variable displacement pump and operable to regulate a mechanism displacement of said variable displacement mechanism at least approximately in accordance with a pressure rate of said motor fluid flow from said fluid motor means:
supplementary energy converting means including said recuperative braking variable displacement pump and said displacement control system and operable to convert said mechanical energy of said mass of said wheeled vehicle to said recuperated energy of said energy accumulating means including said hydraulic accumulator, in order to assist said first load adaptive energy converting means.

44. A regenerative adaptive fluid motor output feedback control system comprising:
a fluid motor output feedback control system including fluid motor and load means, spool valve means.
fluid power means, and output feedback control means;
said fluid motor and load means including fluid motor means and motor load means and accumulating a load related energy;
said spool valve means having at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said fluid motor and load means, a supply power line, and an exhaust power line;
said fluid power means including energy accumulating means being implemented for powering a variable delivery fluid power supply generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means:
said output feedback control means measuring a motor output of said fluid motor means and producing an output feedback control error signal being implemented for modulating said spool valve means;
an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said load related energy of said fluid motor and load means;

an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate an exhaust fluid pressure drop across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust line energy recuperating means;
said energy recuperating pressure drop feedback control system having a significant dynamic performance superiority against said fluid motor output feedback control system by having either a significant frequency-response superiority or a significant final-transient-time superiority against said fluid motor output feedback control system;
a supply line pressure drop feedback control system including said variable delivery fluid power supply and operable to regulate a supply fluid pressure drop across said spool valve means by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
said supply line pressure drop feedback control system having a significant dynamic performance superiority against said fluid motor output feedback control system by having either a significant frequency-response superiority or a significant final-transient-time superiority against said fluid motor output feedback control system;

a load adaptive Anergy regenerating system including first load adaptive energy converting means, said energy accumulating means, and second load adaptive energy converting means.
said first load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said load related energy of said fluid motor and load means to a recuperated energy of said energy.
accumulating means for storing and subsequent use of said recuperated energy;
said second load adaptive energy converting means including said supply line pressure drop feedback control system and operable to convert said recuperated energy of said energy accumulating means to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means, 45. The system according to claim 44 , wherein said fluid motor output feedback control system is represented by a fluid motor position feedback control system.
wherein said output feedback control means are represented by position feedback control means, wherein said motor output is represented by a motor position, and wherein said output feedback control error signal is represented by a position feedback control error signal.

46. A regenerative adaptive press drive system comprising;
a fluid motor position feedback control system including fluid motor and load means, spool valve means, fluid power means, and position feedback control means;
said fluid motor and load means including fluid motor means of a hydraulic press and accumulating a compressed fluid energy of said fluid motor means of said hydraulic press:
said spool valve means having at least three fluid power lines including a motor line conducting a motor fluid flow to or a motor fluid flow from said fluid motor means of said hydraulic press, a supply power line, and an exhaust power line;
said fluid power means including energy accumulating means being implemented for powering a variable delivery fluid power supply generating a pressurized fluid stream being implemented for powering said supply power line of said spool valve means;
said position feedback control means measuring a motor position of said fluid motor means and producing a position feedback control error signal being implemented for modulating said spool valve means;
an exhaust line energy recuperating means for varying a counterpressure rate in said exhaust power line and for recuperating said compressed fluid energy of said fluid motor means of said hydraulic press;

an energy recuperating pressure drop feedback control system including said exhaust line energy recuperating means and operable to regulate an exhaust fluid pressure drop across said spool valve means by varying said counterpressure rate in said exhaust power line by said exhaust.
line energy recuperating means;
said energy recuperating pressure drop feedback control system having a significant dynamic performance superiority against said fluid motor position feedback control system by having either a significant frequency-response superiority or a significant final-transient-time superiority against said fluid motor position feedback control, system.
a supply line pressure drip feedback control system including said variable delivery fluid power supply said operable to regulate a supply fluid pressure drop across said spool valve means by varying a pressure rate of said pressurized fluid stream by a variable delivery means of said variable delivery fluid power supply;
said supply line pressure drop feedback control system having a significant dynamic performance superiority against said fluid motor position feedback control system by having either a significant frequency-response superiority or a significant final-transient-time superiority against said fluid motor position feedback control system;

a load adaptive energy regenerating system including first load adaptive energy converting means said energy accumulating means, and second load adaptive energy converting means:
said first, load adaptive energy converting means including said energy recuperating pressure drop feedback control system and operable to convert said compressed fluid energy of said fluid motor means of said hydraulic press to a recuperated .energy of said energy accumulating means for storing and subsequent use of said recuperated energy:
said second load adaptive energy converting means including said supply line pressure drop feedback control system and operable to convert said recuperated energy of said energy accumulating means to a regenerated energy of said pressurized fluid stream being implemented for powering said supply power line of said spool valve means, 47. The drive system according to claim 46 , wherein said fluid motor means include at least one hydraulic cylinder having a loadable chamber being loaded against a frame of said hydraulic press, and wherein said compressed fluid energy of said fluid motor means of said hydraulic press includes a compressed fluid energy of said loadable chamber of said hydraulic cylinder of said hydraulic press.