US3266424A

US3266424A - Fluid system including variable displacement pump

Info

Publication number: US3266424A
Application number: US407625A
Authority: US
Inventors: Ernest V Bunting
Original assignee: Massey Ferguson Inc
Current assignee: Massey Ferguson Inc
Priority date: 1964-10-27
Filing date: 1964-10-27
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

Aug. 16, 1966 Filed Oct. 27, 1964 E. V. BUNTING FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP 7 Sheets-Sheet l s\\\.\\\l1 f 1% DEMAND I7 2 6/ a A Tr My k iv in 1 SUMP INVENTOR.

TT RNEYJ Aug. 1966 E. v. BUNTING 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP ATT NEYS Aug. 1966 E. v. BUNTING 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Filed 001:. 27, 1964 7 Sheets-Sheet 3 INVENTOR. [R/VEST M 5U/V7/NG BY ATT NEYS Aug. 16, 1966 E. v. BUNTING 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Filed Oct. 27, 1964 '7 Sheets-Sheet 4 R66 (IL/7 TIA 6 VAL V5 DEM/M D INVENTOR.

7?? 7 fzwesf L 511171. 29

A TTORNEYJ' 1966 E. v. BUNTING 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Filed Oct. 27, 1964 '7 Sheets-Sheet 5 I NVENTOR 966 E. v. BUNTlNG 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Filed Oct. 2'7 1964 7 Sheets-Sheet 6 Aug. 16, 1966 E. v. BUNTlNG 3,266,424

FLUID SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Filed 001;. 27, 1964 7 Sheets-Sheet 7 INVENTOR.

ATYDR/VEYS' United States Patent 3,266,424 FLUHD SYSTEM INCLUDING VARIABLE DISPLACEMENT PUMP Ernest V. Bunting, Detroit, Mich, assignor to Massey- Ferguson Inc, Detroit, Miclr, a corporation of Maryland Fiied Get. 27, 1964, Ser. No. 407,625 40 Claims. (Cl. 10339) This invention relates to "a system for supplying variable volumes of fluid at a substantially constant delivery pressure in accordance with demand and, in particular, to such a system comprising a variable displacement pump including pressure modulated metering valve means controlling displacement of the pump by metering varying amounts of charging fluid thereto to be pumped thereby, and is a continuation-in-part of United States patent application Serial Number 214,562, now abandoned, filed August 3, 1962, in the name of Ernest V. Bunting.

Systems have been proposed heretofore for deivering variable volume-s of fluid at a relatively high discharge pressure to various types of fluid operated devices or motors in accordance with the demand of the latter as sensed lay changes in diiferential between two control pressures. More specifically, known systems of this type comprise a source of charging fluid at a moderately low charging pressure, usually a positive displacement auxiliary of first stage pump of the gear type, having its output connected to the inlet of a main or second stage pump the output of which is connected to one or more fluid operated motors or devices imposing a variable demand on the second stage pump for delivery of fluid therefrom at-su-bstantially high pressures, the volume of fluid delivered from the second stage high pressure pump to the variable demand-imposing motors being controlled by the volume of fluid admitted to the pumping chambers of such high pressure pump from the first stage low pressure pump in accordance with differential changes between the charging pressure of the first stage pump and the delivery pressure of the second stage pump as demand varies. On the other hand, the manner in 'which these control pressures constituted by the low charging pressure of the first stage pump and the high delivery pressure of the second stage pump have :coacted with each other and various components of the fluid system to vary output or the vo ume of fluid delivered from the second stage pump has varied considerably.

For example, in one system of this type comprising a first stage or charging pump supplying variable amounts of charging fluid to a second stage or main pump in accordance with demand imposed on the latter, variation of the volumetric discharge of the second stage pump has been accomplished by relieving the charging pressure of the first stage pump when a predetermined delivery pressure is reached iby the second stage pump; that is, more specifically, the charging pressure of the first stage pump and delivery pressure of the second stage pump have been imposed in concert on one side of a common spring biased pressure relief and fiow control valve, .which when a predetermined second stage delivery pressure is reached, opens to sump to relieve the charging pressure of the first stage pump and reduce the volume of fluid supplied thereby to the second stage pump. In yet another prior system of this type in which the second stage pump is of the type comprising radial reciprocable pistons driven on pumping strokes by an eccentric drive cam mechanism in a cam case and returned on intake strokes by return springs associated therewith, the delivery pressure of the second stage pump has been communicated to a pressure sensing servo lvalve construction and to the cam case of the pump to oppose inward movement of the pump pistons on an intake stroke thereof under the influence of the return springs, thereby controlling the volume of fluid supplied to the pumping chambers in accordance with changes in diiferential between the charging pressure of the first stage pump and the delivery pressure of the second stage pump.

Still other examples could be given of fluid systems of this general type aforementioned in which control pressures constituted by a first stage charging pump and a second stage delivery pump have been utilized to control the volumetric discharge of the second stage pump in accordance with demand imposed thereon. However, suffice it to say at this point that operation of these systems has depended at least in part on the use of either pressure sensitive servo valves to control coaction between the aforementioned contro l pressures, or spring biased pressure relief or flow control valves performing a somewhat similar function to dump, for example, charging pressure upon reaching a predetermined delivery pressure from the second stage pump, or a piston type second stage pump having spring biased pump pistons to urge the latter on a return stroke thereof, of various combinations of such devices. As a result, due to the need of such pressure sensitive servo valves on the one hand or spring means on the other acting either on a pressure relief and flow control valve or the pump plungers themselves of the second stage pump, variable factors are imposed in such systems affecting accuracy of control of the supply of charging fluid to the second stage pump on intake strokes of the latter and, hence, control of the volumetric discharge of the latter.

In addition, the connection of the first stage pump to the second stage pump of the piston type aforementioned for supplying charging fluid to the latter, and irrespective of the particular arrangement of control system utilized therewith, has typically involved supplying charging fluid at some relatively low and often variable charging pressure into a common inlet gallery associated With the second stage pump, from which gallery the charging fluid is permitted to flow at random to various ones of the multiple pumping chambers of the piston type second stage pump, thereby further contributing to .loss in accuracy of control of the volume of fluid delivered by the second stage pump.

By comparison, the present invention is directed to a system and pumping mechanism thereof for supplying variable amounts of fluid to one or more fluid pressure operated motors or devices in accordance with the demand of the latter, and characterized by a source of charging fluid at a low substantially constant charging pressure connected to a main pump, preferably of the reciprocable piston type, through a pressure responsive metering valve means which is automatically variably movable between two extreme positions respectively reducing and increasing the volume of metered flow therethrough to the pumping chambers of the second stage pump in accordance with changes in the delivery pressure from the main pump. In this respect, the invention is further particularly characterized by the fact that the flow of metered charging fluid to the pumping chambers of the main pump is very accurately metered in accordance with demand imposed on the latter without requiring pressure sensitive servo valves of the type aforementioned or return springs acting on the pistons of the main pump to urge the latter on a return stroke, thereby providing extremely accurate control of the volume of fluid supplied to the pumping chambers of the main pump and, hence, control of the volumetric discharge of the latter in accordance with the demand impose-d thereon.

Furthermore, the invention is particularly characterized by the fact that the aforementioned metering valve means comprises a valve body having a plurality of spaced inlet ports respectively communicating with individual ones of the pumping chambers of a main reciprocable piston type pump, and a metering valve member freely variably movable relative to the aforementioned valve body between first and second positions respectively closing and opening said ports to a substantially uniform extent solely in response to changes in the delivery pressure of the main pump.

The present invention is further characterized by the fact that the aforementioned charging pressure of the charging fluid and the delivery pressure of the main pump act on opposed differential operating areas associated with the metering valve means, whereby a predetermined design delivery pressure is established for the main pump in accordance with preselecting the ratio of the aforementioned areas and the constant value of the aforementioned charging pressure, the charging pressure being selectively variable to increase or decrease the latter thereby automatically increasing or decreasing the predetermined design delivery pressure aforementioned.

According to another aspect of the invention, the latter is further characterized by means operable automatically in response to a delivery pressure from the main pump in excess of a predetermined maximum to connect such excess pressure with the metering valve means to insure positive movement of the latter to a position closing or substantially closing the aforementioned ports communicating with the respective pumping chambers of the main pump to shut down flow thereto, thereby providing a positively acting means to insure shutting down of the main pump in the event that the metering valve means should tend to stick in an open position.

In another of its aspects, the invention is characterized by a connection including a two-Way flow restriction between the metering valve means and a low pressure portion of the system such as a sump or charging pressure to permit flow of fluid between the metering valve means 'and such low pressure portion of the system to dampen the tendency of the metering valve means to oscillate while moving in response to the delivery pressures imposed thereon, thereby further contributing to accuracy of control of the charging fluid metered therethrough. In regard to this latter connection, it is characterized in addition by pressure relief valve means adapted to automatically communicate the portion of the metering valve 'means acted upon by the positive shut down means aforesection to illustrate certain details thereof, of a preferred embodiment of a radial piston type .pump particularly adapted for use in the system of FIGURE 1;

FIGURE 3 is an enlarged sectional view taken on line '33 of FIGURE 2;

FIGURE 4 is a fragmentary sectional view taken on -line 4-4 of FIGURE 3;

FIGURE 5 is a fragmentary sectional view taken on line 55 of FIGURE 3;

FIGURE 6 is a fragmentary sectional view taken on line 66 of FIGURE 2;

FIGURE 7 is a schematic view of a fluid system illustrating another of the preferred embodiments of the invention;

FIGURE 8 is a cross-sectional view of a prefer-red embodiment of a radial piston type pump particularly adapted for use in the system of FIGURE 7;

FIGURE 9 is a sectional view taken on line 99 of FIGURE 8;

FIGURE 10 is a sectional view taken on line I010 of FIGURE 8; and

FIGURE 11 is a sectional view taken on line I111 of FIGURE 8.

Referring now in particular to FIGURE 1 of the drawings, there is illustrated a fluid system comprising the sump 10 for fluid communicating through the connection 12 to the suction or inlet side of a charging pump 14, preferably of the positive displacement gear pump type, which supplies fluid under pressure through the connection 16 to a chamber 18 between a metering valve assembly indicated generally at 20 and a pressure relief valve assembly indicated generally at 22. The charging pressure or pressure of the charging fluid delivered by the pump 14 to the chamber 18 is determined in accordance with the setting of the pressure relief valve assembly 22 comprising the valve member 24 reciprocably mounted in valve body 26 and acted upon by the spring 28 abutting the support 30 which is adjustable by any suitable means such as the threaded member 32. Thus, adjustment of the spring 28 to a particular setting determines a substantially constant predetermined charging pressure for the delivery of charging pump 14, pressures in excess of such predetermined constant charging pressure causing the valve member 24 to move to the right in FIGURE 1 to dump excess pressure through the port 34 and connection 36 to sump.

The metering valve assembly 20 comprises the valve body 38 in which the metering valve member 40 is mounted for reciprocation, the valve member having one biasing, operating or control area 42 exposed to the charging pressure in chamber 18 and another actuation operating or control area 44 abuttable with yet movable relative to one end of a piston 46 suitably slidably supported in a partition 48 within the valve body 38 and including a biasing operating or control area 50 at the other end thereof. As will become more apparent hereinafter, the biasing, operating or control area 50 of the piston 46 is exposed in a chamber 52 at one side of partition 48 and communicating through connection 54 with the fluid delivered to the discharge connection 56 from the discharge side of a piston type main pump indicated generally at 58 to one or more fluid operated motors or devices imposing a variable demand thereon as indicated at 60. The exhaust of at least part of the demand 60 is indicated as communicating through the connection 62 with the connection 16 at the delivery side of the charging pump 14 for flow to the chamber 18, while another part of the demand may communicate through connection 63 directly to sump.

The metering valve body 38 further comprises a valve port 64 communicating chamber 18 through connection 66 to a conventional spring biased one-way inlet valve assembly 68 of main pump 58 for flow to a pumping chamber 70 thereof formed by a cylinder 72 and the outer end of a piston 74 reciprocably disposed therein, the inner end of the piston extending out of the open inner end of the cylinder and being engageable with a drive cam mechanism 76 mounted eccentrically on a power driven shaft 78 to drive the piston into the cylinder on a pumping stroke and permit outward movement thereof on an intake stroke. Fluid so pumped within the pumping chamber 70 is communicated through the conventional spring biased one-way outlet valve assembly 80 to the discharge connection 56 and the demand 60, the fluid in the discharge connection being communicated at its delivery pressure to the chamber 52 and the operating or control area 50 of the piston 46 through connection 54 as aforedescribed.

At this juncture, although FIGURE 1 schematically illustrates a main pump 58 having but one pumping chamber 70 communicating with one port 64 and chamber 18, it will be understood that in actual practice the main pump could include a plurality of cooperable piston and cylin ders each defining a pumping chamber communicating with the chamber 18 through an individual inlet port 64, and discharging into a common discharge connection 56. The nature of such a construction will become eminently clear from the description hereinafter of the pump mechanism illustrated in FIGURES 2 through 6.

At this juncture, it should be noted that the present invention may be utilized in a completely open-ended type of fluid system, a completely closed-end type of I fluid system or partially open and partially closed type of system. In other words, in a completely open-ended type of system in which the demand 60 would represent fluid pressure actuable devices the exhaust from which is lost upon actuation thereof through connection 63 to sump, such as, for example, clutches and brakes of an automobile transmission, all of the charging fluid supplied through the connection 16 to the chamber 18 would be supplied by the charging pump 14. Hence, the capacity of the charging pump would ordinarily be slightly greater than the maximum capacity of the main pump 58 to adequately supply the latter for maximum delivery therefrom and accommodate leakage losses and the like. On the other hand, if the demand 6%) consisted entirely of fluid pressure operated devices from which the exhaust was not lost upon actuation thereof, such as double-acting vehicle steering jacks for example, the charging pump 14 could be eliminated and replaced with an accumulator or the like to maintain a predetermined constant charging pressure on such exhaust fluid communicated to the chamber 18 through connection 62.

Thus, it will now be apparent that FIGURE 1 of the drawings illustrates a partially open and partially closed type of fluid system; that is, a system in which the demand 60 represents certain fluid pressure actuated devices of the open type dumping through connection 63 to sump and others of the closed type, the exhaust from the latter communicating through connection 62 to connection 16 and chamber 18. Consequently, in the system illustrated, the charging pump 14 has a maximum output flow capacity something less than the maximum output flow capacity of the main pump 58. More specifically, in the system illustrated, the charging pump may have a maximum output flow capacity of twelve gallons per minute While the output flow capacity of the main pump 58 is variable between zero and twenty gallons per minute; in other words, and ignoring leakage losses and the like, the charging pump is making up twelve gallons per minute lost from devices of the open-end type represented in demand 60, while devices of the closed-end type are supplying eight gallons per minute to the connection 62. Therefore, depending upon the nature of the devices represented by demand 60 in any given system, the sump 10, charging pump 14 and any closed-end type of fluid actuated devices included in demand 60 may be said to constitute asource of charging fluid communicable with the chamber 18 through the connection 16 at a substantially constant charging pressure predetermined by the setting of the pressure relief valve assembly 22.

In addition, a design delivery pressure is predetermned for the variable volume of fluid discharged from the main pump 58 into the connection 56 in accordance with a predetermined selection of the relative sizes of'the operating or control area 42 of the metering valve member 40 subjected to charging pressure in the chamber 18 and of the operating or control area 50 of the piston 46 subjected to such discharge pressure in chamber 52, and selection of the substantially constant charging pressure in chamber 18 by setting the adjustable relief valve assembly 22. In other words, and as will be apparent, the design discharge pressure in connection 56 is a function of charging pressure in the chamber 18 multiplied by the ratio of the operating or control area 42 of the metering valve member 40 to the operating or control area 50 of the piston 46 subjected to such discharge pressure. In the embodiment illustrated in FIGURE 1, setting of the spring pressur of pressure relief valve assembly 22 to establish a substantially constant charging pressure at 161 p.s.i. with the aforementioned ratio of areas being 13.6 results in a design discharge pressure for the main pump 58 of approximately 2189 p.s.-i. Naturally, the spring pressure of the pressure relief valve assembly may be increased or decreased to respectively increase or decrease the charging pressure in chamber 18 and, hence, correspondingly increase or decrease the design delivery pressure from main pump 58 to discharge connection 56.

In operation, changing fluid under the aforementioned preselected changing pressure will be supplied through the connection 16 to the chamber 18 and act upon the operating or control area 42 of the metering valve member 40, While delivery pressure in discharge connection 56 will act in opposition thereto on the operating or control area 50 of piston 46 abutting the metering valve member. As long as the delivery pressure remains at its predetermined design value, the pressure differential acting on the respective operating areas will balance or hold the metering valve member 40 in a particular position relative to the inlet port 64 and a metered volume of charging fluid will be supplied to the pumping chamber 70 of the main pump assembly in accordance with the corresponding requirements of the demand 60. For example, FIGURE 1 illustrates the metering valve member 40 and piston 46 in positions corresponding to maximum opening of the inlet port 64 and maximum flow of charging fluid through the connection 66 to the pumping chamber 70 in accordance with the requirements of the demand 60. Assume now that the demand decreases to a certain extent. Such a decrease in demand will, of course, result a momentary increase in the discharge pressure in the discharge connection 56, which increased pressur is communicated through the connection 54 to the chamber 52 and the operating or control area 50 of the piston 46. Consequently, the resulting change in differential between the substantially constant charging pressure and the increased delivery pressure aforementioned causes the metering valve member 40 to move to the right in FIGURE 1 to throttle the inlet port 64 to decrease the volume of charging fluid metered therethrough. The resulting relative decrease in the volume of charging fluid metered to the inlet side of the main pump assembly 58 results in a decrease in the volume of fluid discharged thereby causing the discharge pressure in discharge connection 56 and acting on the operating or control area of the piston 46 to again reach its predetermined design value. Consequently, the metering valve member 40 is again balanced in a position relative to the inlet port 64 in accordance with the new requirements of the demand 60. In the event that the requirements of the demand increase, a resultant momentary drop in pressure in the discharge connection 56 occurs permitting the metering valve member 40 to move to the left in FIGURE 1 to supply an increased volume of metered changing fluid to the inlet side of the main pump assembly, and pumping of an increased volume of fluid to the demand ultimately resulting in the discharge pressure again reaching its predetermined design value and balancing the metering valve member in a new position relative to the inlet port 64 corresponding to such demand. Naturally, particularly in a system in which the demand 60 represents a relatively great number of fluid actuated devices, such demand can fluctuate continuously and rapidly in which event the metering valve mechanism responds to momentary increases and decreases in the discharge pressure in discharge connect-ion 56 to continuously seek a balanced condition relative to the inlet port 64 to supply a variable metered volume of charging fluid to the main pump assembly 58 for pumping in accordance with such changes in demand.

A chamber 82 is formed in the metering valve body 38 between-the operating or control area 44 of the metering valve member 40 and the partition 48, and is adapted to be communicated with the discharge connection 56 through connection 84 including a conventional pressure relief valve 86 set to open at some maximum delivery pressure in excess of the predetermined design delivery pressure desired in the discharge connection 56. Upon opening of the valve 86 under such excessive delivery pressure conditions as may occur, for example, if metering valve member 40 should stick in an open position while demand decreases, such pressure, being extremely higher than the moderately low charging pressur in the chamber 18, will act on control or operating area 44 of the metering valve member 40 to positively move the latter to the right in FIGURE 1 to substantially close, if not completely close, the inlet port 64 communicating chamber 18 with the inlet to the pumping chamber 70.

The chamber 82 is also adapted for communication with sump through connection 88 to connection 84, the connection 88 including a pressure relief valve 90 including a restrictiv or throttling orifice 92 therethrough. Thus, should the metering valve member 40 otherwise tend to dance or oscillate in either direction while responding to changes in differential pressure as aforedescribed, and particularly rapid changes therein, fluid is permitted to flow at a slow rate in either one of two directions through the orifice 92 between sump and chamber 82 and area 44 of the metering valve member to dampen such oscillations. On the other hand, in the event of a predetermined excessive increase in pressure in the chamber 82, such a pressure increase causes the relief valve 90 to open to dump the chamber 82 to sump.

At this juncture it should be noted that no springs are utilized in association with the metering valve member 40 or with the pump piston 74 to urge the latter on a return stroke. Thus, the pump piston is moved outwardly from its cylinder 72 on an intake stroke solely in accordance with the volume of charging fluid metered through the connection 66 as aforementioned. Under maximum flow conditions through the connection 66, for example, the pump piston may be moved outwardly of its cylinder by the charging fluid so as to always follow and engage the contour of the eccentric drive cam mechanism 76 whether on a pumping or intake stroke. At the other theoretical extreme, with the metering valve assembly 20 completely closed, no metered fluid will be supplied to move the pump piston outwardly of its cylinder at all following a pumping stroke so that the main pump assembly merely idles without supplying any fluid at all. Consequently, the length of the intake stroke of the pump piston and, hence, its pumping stroke and the volume of fluid supplied thereby is determined solely in accordance with the volume of charging fluid supplied to the pump chamber 70 without requiring any return springs associated with the pump piston or springs associated with operation of the metering valve assembly 20, thereby contributing to extreme accuracy of control of the flow of metered charging fluid to the main pump assembly 58 and the volumetric discharge of the latter.

Reference will now be made to FIGURES 2 through 6 illustrating in detail a preferred embodiment of a main pump assembly adapted for use in the system illustrated in FIGURE 1 and aforedescribed, and including therein a metering valve assembly corresponding to the assembly 20, a pressure relief valve assembly corresponding generally to the assembly 22, safety shut-down valve assembly 86 and dampening and high pressure relief valve assembly 90 all previously described.

Thus, the numeral 94 generally indicates a radial piston type high pressure pump assembly corresponding to the main pump assembly 58 previously described and comprising a pump housing 96 having an inlet fitting 98 adapted for communication with a source of charging fluid such as through the connection 16 illustrated in FIG- URE 1 to conduct such charging fluid through passage 100 illustrated in FIGURE 2 to an annular inlet gallery 102 illustrated particularly in FIGURE 3 and corre sponding to the chamber 18 illustrated in FIGURE 1.

Referring particularly to FIGURE 3, a metering valve assembly 104 corresponding to the assembly 20 previously described comprises a hollow spool type metering valve member 106 open at one end thereof and mounted for reciprocation along the axially spaced annular lands 108 to either side of the inlet gallery 102. The metering valve member includes a plurality of spaced openings 110 therein whereby charging fluid in the inlet gallery 102 continuously acts against the interior end wall 112 of the metering valve member which corresponds to the operating or control area 42 previously described. The metering valve assembly further includes a threaded plug or the like 114 secured within the housing and corresponding to the partition 48 previously described to form on opposite sides thereof pressure chambers 116 and 118 corresponding, respectively, to chambers 52 and 82 as aforedescribed. The plug is bored centrally to receive a reciprocable piston 120 corresponding to the piston 46 previously described, one end of the piston being abuttable with an exterior end wall 122 of the metering valve member exposed to pressure in chamber 118 and corresponding to the operating or control area 44 previously described, and the other end 124 thereof corresponding to the operating or control area 50 previously described and exposed to the pressure in chamber 116.

A pressure relief valve assembly 126 corresponding generally to the assembly 22 previously described comprises a hollow relief valve member 128 mounted for reciprocation within a valve body 130 secured in the housing axially opposite the open end of the metering valve memher 106, and provided with an annular port surrounding the relief valve member and communicating through a plurality of circumferentially spaced radially arranged passages 132 with an annular sump gallery 134 communicating through a passage 136 as illustrated in FIG- URE 6 to a fitting 138 as shown in FIGURE 2 adapted to be communicated as by the connection 36 in FIGURE 1 to sump. The relief valve member is shown in a closed position in FIGURE 3, and is movable to the left to communicate charging fluid to the sump gallery to maintain the charging pressure of the fluid in inlet gallery 102 and acting on end wall 112 of the metering valve member 106 at a predetermined maximum as established by the setting of a spring 140 suitably mounted in a bore 142 in drive shaft 144 and acting through a reciprocable pin 146 having a head end thereof engaging the head or leftward end in FIGURE 3 of the relief valve member 148 movable within a vented dashpot chamber 150 suitably secured in the bore 142.

It will be noted also that the relief valve member 128 includes a plurality of apertures 152 adjacent the head end thereof so positioned relative to the other end thereof as to permit charging pressure to first dump charging fluid into a chamber 154 immediately to the left of the valve body 130 in FIGURE 3 prior to dumping the charging fluid to sump as previously described. The fluid so flowing to the chamber 154 is used to lubricate the various bearings and cam drive mechanism associated with the drive shaft 144 and disposed as will be described hereinafter and to provide fluid in the dashpot chamber 150. Lubricating fluid so provided and the drive chamber or cam case 156 is continuously vented to sump gallery 134 through a plurality of passages 158. While not illustrated in FIGURE 3, it will be apparent that means may be provided to adjust the tension of the spring 140 as indicated schematically at 30, 32 in FIGURE 1 to vary the preselected charging pressure for reasons aforementioned.

An annular member 160 is seated immediately around one end of the relief valve body 138 as illustrated particularly in FIGURE 3, and includes -a plurality of circumferentially spaced radially arranged narrow elongate inlet ports 162 each corresponding to a port 64 previously described, and communicating With respective ones of indivdual inlet passageways 164 corresponding to connection 66 previously described. Each passageway 164 opens through a. spring biased one-way inlet valve assembly 166 corresponding to the assembly 68 previously described to a chamber 168 communicating through a passage 170 to respective ones of a plurality of circumferentially spaced radially arranged pumping chambers 172, corresponding to pumping chamber 70 previously described, each defined by a cylinder 174- and the radially outer end of a pump piston 176 reciprocably disposed therein, the inner end of each of the pump pistons being projectable out of the radially inner end of each cylinder int-o the aforementioned drive chamber or cam case 156. Each chamber 168 associated with each pumping chamber 17 4 further includes a one-way spring biased discharge valve assembly 178, corresponding todischarge valve assembly 80 previously described, to conduct fluid pumped within the respective pumping chambers to an annular discharge gallery 180 corresponding to the discharge connection 56 previously described. At this juncture, it will be noted that the respective inlet and discharge valve assemblies 166 and 178 each include annular retaining cages 1182 including a plurality of openings 184 therein for inlet and discharge flow therethrough, and to retain the respective valve members of the assemblies and the springs therefor in position within such cages.

The radially inner ends of the respective pump pistons 17 6 are adapted for engagement with the outer peripheral surface of an annular cam follower or drive ring 186 supported about the periphery of a circular drive cam 188 by means of the roller bearing assemblies 190, the drive cam 188 being formed integral with or otherwise rigidly secured eccentrically to the aforementioned drive shaft 144. The drive shaft and drive mechanism mounted thereon are suitably rotatably supported within the cam case 156 by means of the axially spaced roller bearing assemblies 192 to either side of the eccentricdrive cam 188. The end of the drive shaft 144 exteriorly of the housing 96 is splined or otherwise formed for suitable driving connection with a member 194 driven from a suitable power source such as a vehicle engine.

As will now be apparent, and referring particularly to FIGURE 4, as the eccentric drive cam rotates, the cam follower and drive ring 186 moves about the drive chamber or cam case 156 so as to be progressively engageable with the inner end of the pump pistons 176 to drive the latter on a pumping stroke into the pumping chambers 172 While permitting other pump pistons to move outwardly of their cylinders on intake strokes into the drive chamber or cam case in accordance with the metering of charging fluid thereto.

The discharge gallery 180- is connected by interior passage means wi-thin the housing 96, not shown, to an outlet or discharge fitting 196 as shown in FIGURE 2 adapted to be communicated as by the connection 56 previously described to one or more fluid actuated devices constituting the demand on the main pump. At the same time, and referring particularly to FIGURE 6, the discharge gallery 180 and the discharge pressure therein are communicated to chamber 116 and the end area 124 of the piston 120 of the metering valve assembly through the passageway 198 corresponding to the connection 54 in FIGURE 1. The discharge gallery is also adapted to be automatically communicated in response to a predetermined maximum pressure therein in excess of the desired delivery pressure as aforedescribed t-o chamber 118 and the exterior wall 122 of metering valve member .106 through passageway 200 including pressure relief valve assembly 202 corresponding, respectively, to connection 84 and relief valve assembly 86 illustrated in FIGURE 1. Finally, a passageway 204 including pressure relief valve assembly 206 including a two-way flow throttling or restricting orifice 208 therein is disposed between the passageway 200 and the sump gallery 134 and, corresponding to the connection 88 and the valve assembly 90 previously described, provides for two-way restricted flow of fluid between sump and the chamber 118 to dampen any tenden- CAD cy of the metering valve member 106 to oscillate in response todifferential pressure changes therein while, at the same time, being set to open to dump the chamber 118 to the sump gallery in response to a predetermined excessive pressure occurring therein. In addition, fluid may flow through the orifice 208 to or from chamber 118 as metering valve member 106 moves and pressurized fluid escaping past the metering valve member into chamber 118 may be vented therefrom through orifice 208, all for the purpose of maintaining chamber 118 at sump pressure.

The operation of the pump assembly illustrated in FIG- UR-ES 2 through 6 and aforedescribed should now be readily apparent from the foregoing description with reference to the previous description of the system illustrated schematically in FIGURE 1. Consequently, the operation of the pump assembly will only be briefly summarized at this point. Thus, during power rotations of the driving eccentric cam mechanism to reciprocate the respective pump pistons on a pumping stroke and to permit the re-' turn thereof under the force of charging fluid on a return stroke, the charging buid admit-ted to the inlet gallery 1102 and acting on internal end wall 112 of the metering \nalve member is held at a predetermined constant charging pressure by the action of the pressure relief valve assembly 126 which will open in response to a pressure in excess of the predetermined desired constant charging pressure to first dump charging fluid into the chamber 154 to provide lubricant for the drive mechanism and then dump charging fluid into the sump gallery 134. The discharge pressure in discharge gallery 180 is transmitted to the chamber 116 and the end area 124 of the piston of the metering valve assembly, whereby the latter is movable among an infinitely variable number of positions between -a substantially full open position relative to the ports 162 as illustrated to FIGURE 3 and a substantially fully closed position to the left thereof in response to variations in the differential between the discharge pressure in the discharge gallery and the substantially constant charging pressure as demand imposed on the pump varies. Thus, the metering valve member 106 meters charging fluid simultaneously through the individual inlet ports 162 to the individual inlet passages 16-4 and the respective pumping chambers .172 in accordance with demand, it being noted that all of the inlet ports 162 are always opened or closed to a substantially uniform extent in response to metering valve movement.

The metering valve. assembly 104 of FIGUR-E 3 is shown in a substantially rfull open position corresponding to that illustrate-d in FIGURE 1, and in which a maximum volume of charging fluid is supplied through the respective pump pistons outwardly of their cylinders on an intake stroke to a maximum extent substantially following the contour of the cam tfollower and drive ring 186 as it moves away from a given cylinder. In the event of a reduction in demand causing the metering valve assembly to move to the left in FIGURE 3, the volume otf charging fluid metered therethrough and through the inlet ports 162 will be diminished, thereby causing the pump pistons 1-76 to move outwardly of their cylinders to a lesser extent depending upon the amount of metered flow involved to govern the volumetric discharge of the pump. During metering valve movement, the relief valve assemblies 202 and 206, the latter including the orifice 208, tfIlIlCtlOIl as previously described.

Referring now more particularly to FIGURE 7, there is illustrated an alternative embodiment of the present invention comprising the sump 3-10 for supplying fluid through the connection or line 31-2 to the inlet side Oif the charging pump 314, preferably of the positive displacement gear type, which supplies fluid under pressure through the filter 313 and heat exchanger 315 and through the connection or line 616 to the inlet gallery 3-17 of the m-ainpump. The charging pump 6-14 is connected by a fluid line 31 1 to a regulating valve 318 which in turn is connected by a fluid line 319 to another fluid line 3 16 13 fluid pressure to the first end 344 of the valve member 340, it closes when the discharge fluid pressure decreases to trap fluid in the actuation chamber 382. The fluid pressure in the fluid line 384 and in the chamber 382 is vented to the inlet gallery 317 through a dampening valve generally shown at 390. The dampening valve 390 has an orifice the size of which is controlled by the position of the spring biased needle 392. The needle 392 controls the rate of flow from the actuation chamber 382 to the inlet gallery 317, and vice versa, thereby to control the rate of movement of the valve member 340. The dampening valve 390, therefore, dampens oscillations of the metering valve 320, and more particularly, oscillations of the valve member 340.

Let it be assumed that there has been a reduction in demand, hence, an increase in discharge fluid pressure to open relief valve 386 to supply fluid pressure to chamber 382, and a subsequent closeure of relief valve 386 to allow the valve member 340 to move in a flow increasing direction as the dampening valve 390 allows fluid to pass from chamber 382 to the inlet gallery 317. Further assuming that in this condition there is suddenly a high demand, and consequently a rapid decrease in discharge fluid pressure, it is required that the valve member 340 be quickly moved in a flow increasing direction. Such a rapid movement of the valve member 340 is obtained by a quick recovery valve generally shown at 361. The quick recovery valve 361 is subjected to discharge fluid pressure by a fluid line 355. The discharge fluid pressure acts against valve element 363, which element controls the flow of fluid through the port 365 and fluid line 388 to inlet gallery 317. The valve element 363 is urged toward the closed position by discharge fluid pressure and toward the open position by a rod 367 which is acted upon by a spring element 369. In the event that there is a sudden demand for discharge fluid, the discharge fluid pressure in the fluid line 355 will decrease thereby permitting the valve element 363 to move to the left as shown in FIG- URE 7 thereby opening port 365 to allow the fluid in the chamber 382 and line 384 to flow more rapidly through line 388 to the inlet gallery 317 than it would flow through the dampening valve 390 alone.

The operation of the pump system illustrated in FIG- URE 7 should now be readily apparent from the foregoing description; however, the operation of the pumping system will be briefly summarized at this point. The pumping system for supplying variable volumes of fluid in accordance with the demand utilizes a plurality of pumping chambers 370, which pumping chambers acquire pumping action due to the movement of a piston 374 driven by a cam 376. The pumping chamber 370 supplies fluid under pressure to a discharge or demand 360 and is supplied a source of charging fluid, under a substantially constant pressure, through a line 316, an inlet gallery 317, ports 364 and individual passages 366 leading to each respective pumping chamber 370. There is a metering valve 320 disposed intermediate the source of charging fluid and the pumping chamber 370 to control the amount of the charging fluid supplied to the pumping chamber 370. The metering valve 320 has a valve member 340, which may have an open and a closed position, but moves in a flow increasing and a flow decreasing direction to control the amount of fluid through the ports 364. The valve member 340 is biased in the flow decreasing direction by a piston 346 abutting thereagainst, which piston has a first end 350 supplied fluid under pressure through a modulating valve 331 in proportion to the discharge fluid pressure from the pumping chambers 370. The valve member 340 is biased in a flow increasing direction by the springs 325 acting against the first end thereof. The amount of fluid supplied the pumping chambers 370 is, therefore, a function of the discharge fluid pressure which in turn is a function of the demand on the pumping system.

The pumping system of FIGURE 7 also includes an actuation system whereby, upon a rapid decrease in the demand of the fluid from the pumping system, the discharge fluid pressure will increase and hence rapidly move the metering valve in a flow decreasing direction. This is done through a relief valve 386 which allows discharge fluid to act against a second end 344 of the valve member 340 when the discharge fluid pressure exceeds a predetermined maximum to rapidly move the valve member 340 in a flow decreasing direction. The actuation system, Which comprises the relief valve 386 and the actuation chamber 382, moves the valve body member 340 in a flow decreasing direction and a dampening valve 390 restricts the flo'w of fluid between the second end 344 of the valve member 340 and the inlet gallery 317 thereby to dampen oscillations of the valve member 340.

The pumping system also includes a secondary relief valve 391 to allow fluid, in excess of that required to rapidly move the valve member 344 in a flow decreasing direction to flow to the inlet gallery 317. A quick recovery valve 361 is provided to allow the valve member 340 to rapidly move in a flow increasing direction in the event there is a sudden demand on the system, and hence a sud-den decrease in discharge fluid pressure, by allowing fluid to flow from the chamber 382 to the inlet gallery 317 at a faster rate than it could flow through dampening valve 390 alone.

Referring now to FIGURES 8 through 11, there is shown an illustrative embodiment of the pumping system shown in FIGURE 7. The reference numbers in FIGURES 8 through 11 are the same as those used in FIGURE 7 and point out corresponding elements and components. The pump generally shown at 330 in FIG- URE 8, has radially disposed pistons 374 cooperating with the cylinder block 334 to form pumping chambers 370. The pumping chambers are supplied fluid from 1 a source which passes through ports 364, which are con trolled by the valve member 340, through passages 366, and check valve 368. Discharge fluid pressure is passed to the pump outlet through check valves 380. The radial pistons 374 are actuated by a cam shaft 336 which in turn is splined to the power shaft 337. The cam shaft 336 is supported within the cylinder block by a double row of tapered roller bearings 338 and supports an outer sleeve 339 through a series of roller bearings communication, through passage 355, with discharge fluid pressure, the quick recovery valve 36 1, and the relief valve 386. The dampening orifice 381 is shown in the passage between the relief valve 386 and the quick recovery valve 361. There is also shown in FIGURE 9 the piston 346 and the discharge fluid pressure su-pply passage 354 which communicates with the modulating valve 331. An orifice between the passage 354 and the inlet gallery 317 is shown at 335.

FIGURE 10 discloses the second end 344 of the valve member 340 and the pressure chamber 382 in communication with the dampening valve 390. Also shown in FIGURE 10 is a cross-section through the secondary relief valve 391. The passage 388 leading to the inlet gallery 317 is shown in FIGURE 10 as well as the passage 384 which communicates the pressure chamber 382 with the quick recovery valve 361.

FIGURE 11 discloses the relative positioning between the radial pistons 374 and the drive shaft 337, crank shaft 336, and sleeve 339.

As will be apparent to those skilled in the art, the metering valve of the present invention accomplishes two separate and distinct functions. The first function is that of supplying the total amount of fluid available to the pumping system under a substantially constant pressure. The second function is that of substantially simultaneously and equally distributing variable amounts of the total amount of fluid so supplied to the receptive pum ing chambers under a substantially constant pressure. Accordingly, it will be apparent that each of the funct-ions of the metering valve of the instant invention may be accomplished by a separate valve, regulator, or like fluid control device.

As mentioned hereinbefore, the pistons of the radial pump of the instant invention are moved on the pumping stroke by a cam, and move on the intake stroke in response to the volume of the fluid supplied at a substantially constant pressure to the chambers. It is an important attribute of the instant invention that the metering valve substantially simultaneously dis-tributes equal but variable amounts of fluid under a substantially constant pressure to the receptive pumping chambers, since such a supply of fluid over the entire range of demand on the pump makes the effect of gravity on fluid entering the pumping chambers negligible. The effect of gravity may be appreciable in a pressure variable system wherein a valve is utilized which is responsive to variation in demand to vary charging pressure and, hence, the total flow of fluid avialable to supply the respective pumping chambers through their individual inlets. Thus, when the demand on the pump is low so that the total flow available to the pump is being supplied at a low charging pressure, gravity will cause more fluid to flow to the lower pumping chambers of a radial piston pump than to the upper pumping chambers because the force of gravity acts with the low charging pressure of the fluid to enhance movement of the pistons in the lower chambers and filling of the latter, while it acts against the low charging pressure to oppose movement of the pistons in the upper chambers and filling of the latter. Consequently, the lower pumping chambers will take in more fluid on the intake stroke than will the upper pumping chambers. This results in uneven pumping between the upper and lower pumping chambers when the demand on the pump is low. However, the effect of gravity is negligible in the instant invention comprising a constant pressure charging system wherein the metering valve simulataneously distributes equal but variable amounts of fluid under a substantially constant pressure over all ranges of demand on the pump. In other words, the metering valve of the instant invention is supplied with a source of fluid under a substantially constant pressure irrespective of the demand on the pump, and distributes equal amounts of this fluid to respective pumping chambers at a substantially constant pressure which is suflicient to make the effect of gravity on fluid entering the pumping chambers substantially negligible.

As is apparent from the foregoing description, the present invention provides a unique pumping system wherein a main pump supplies fluid pressure to fluid actuated components or accessories using fluid pressure in accordance with the demand by controlling a metering valve as a function of discharge fluid pressure to control the amount of charging fluid supplied to the main pump.

The invent-ion has been described in an illustrative manner and it is to be understood that the terminology which has been used herein is intended to be in the nature of words of description rather than limitation.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclu- 16 sive property or privilege is claimed are defined as follows:

1. A system for supplying variable volumes of fluid in accordance with demand comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving said members in one direction relative to each other on a pumping stroke and permitting relative movement thereof in another direction on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chambers on pumping strokes thereof, a source of charging fluid under a substantially constant charging pressure, and means including pressure responsive metering valve means having a plurality of inlet ports respectively communicating said source with respective ones of said pumping chambers and a metering valve member variably movable between first and second positions respectively closing and opening said ports to a substantially uniform extent to meter equal amounts of charging fluid to said respective pumping chambers on intake strokes thereof, said valve member being variably movable between said positions in response to changes in said discharge pressure.

2. A variable displacement pumping mechanism comprising a cylinder block including a plurality of spaced radially arranged cylinders each having an inner end opening into a drive chamber, a plurality of pump pistons respectively reciprocably mounted in said cylinders and each having an inner end projecting into said drive chamber and an outer end cooperable with a respective cylinder to form a plurality of variable volume pumping chambers, rotatable drive means in said drive chamber progressively engageable with said inner ends of said pump pistons to drive the latter outwardly on pumping strokes and permitting inward movement thereof on intake strokes, discharge means communicating with said pumping chambers for receiving fluid therefrom at discharge pressure on pumping strokes, and means for connecting said pumping chambers to a source of charging fluid under a substantially constant charging pressure, said last-named means including pressure differential responsive metering valve means variably movable between first and second positions respectively relatively reducing and increasing the volume of flow therethrough to meter a predetermined variable volume of charging fluid to said pumping chambers on intake strokes thereof, said metering valve means being automatically variably movable between said positions in response to changes in differential pressure between said charging pressure and said discharge pressure, said metering valve means including a body member having a plurality of spaced radially arranged inlet ports respectively communicating with respective ones of said pumping chambers, a metering valve member movable relative to said body member between said first and second positions respectively closing and opening said parts to an equal extent, piston means movable relative to and abutable with said metering valve member, and first and second opposed differential operating areas respectively on said metering valve member and said piston means respectively responsive to said charging pressure and said discharge pressure and differential changes therebetween to move said metering valve member between said positions.

3. The pumping mechanism according to claim 2 in which said source includes a sump and said metering valve member includes a third operating area opposed to said first operating area, and further comprising means including pressure relief valve means operable automatically in response to a pressure in excess of a predetermined maximum in said discharge means to connect the latter with said third operating area to positively move said metering valve member to said first position thereof, and means including pressure relief valve means having a twoway flow restriction therein adapt-ed to communicate said third operating area to sump to dampen oscillation of 17 said metering valve member in moving between said positions, said last-named pressure relief valve means being operable automatically in response to a pressure act-ing on said third operating area in excess of a predetermined maximum to communicate the latter with said sump.

4. The pumping mechanism according to claim 3 further comprising means for selectively changing said charging pressure to change said predetermined design discharge pressure.

5. A system for pumping variable volumes of fluid comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving said members in one direction relative to each other on a pumping stroke and permitting relative movement thereof in another direction on an intake stroke, a, source of charging fluid, and means including metering valve means communicating said source with said pumping chambers to simultaneously meter and distribute respective equal volumesof charging fluid to respective ones of said pumping chambers on intake strokes thereof and being movable between first and second positions respectively relatively reducing and increasing the volume of metered flow therethrough to said respective ones of said pumping chambers to a substantially uniform extent.

6. The system according to claim 5 in which said metering valve means comprises a plurality of inlet ports respectively communicating with respective ones of said pumping chambers, and a metering valve member movable between said first and second positions respectively simultaneously closing and opening said ports to a substantially uniform extent.

7. A variable displacement pumping mechanism comprising a cylinder Iblock including a plurality of spaced radially arranged cylinder members, a plurality of piston members respectively reciprocably mounted in said cylinder members to form a plurality of variable volume pumping chambers, drive means for moving said members in one direction relative to each other on a pumping stroke and permitting relative movement thereof in an opposite direction on an intake stroke, and means for connecting said pumping chambers to a source of charging fluid, said last-named means including metering valve means movable between first and second positions respectively reducing and increasing the volume of flow therethrough to respective ones of said pumping chambers to a substantially uniform extent to meter equal volumes of charging fluid to said respective pumping chambers on intake strokes thereof.

8. The variable displacement pumping mechanism according to claim 7 in which said metering valve means comprises a body member having a plurality of spaced radially arranged elongate inlet ports respectively communicating with respective ones of said pumping chambers, and a metering valve member movable relative to said body member between said first and second positions respectively closing and opening said ports to a substantially uniform extent.

9. A pump system for supplying variable volumes of fluid in accordance with demand comprising in combination at least one pair of first and second relatively rnovable pumping members defining a variable volume pumping chamber, drive means for moving said first and second pumping members in one direction relative to one another on a pumping stroke and permitting relative movement therebeteen on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chamber on a pumping stroke, a source of charging fluid under a substantially constant pressure, valve means communicating with said source and said pumping chamber movable in a first direction to increase fluid flow from said source to said pumping chamber and movable in a second direction to decrease fluid flow from said source to said pumping chamber, first biasing means operating 'on said valve means to urge the latter in said second direction as said discharge pressure increases, second biasing means operating on said valve means for urging said valve means in said first direction in opposition to said first biasing means, and actuation means operable on said valve means for rapidly moving said valve means in said second direction to rapidly decrease fluid flow from said source to said pumping chamber when said discharge pressure reaches a predetermined maximum.

10. A pump system according to claim 9 in which said actuation means comprises a relief valve for allowing discharge fluid to act upon said valve means when said discharge pressure exceeds a, predetermined maximum.

11. A- pump system according to claim 9 further comprising dampening means connected to said valve means for controlling the rate of movement of said valve means in said first direction and said second direction.

12. A pump system according to claim 9 in which said first biasing means includes a modulating valve means for supplying'fluid pressure to said valve means in proportion to said discharge fluid pressure.

13. A pump system according to claim 9 in which said second biasing means includes a spring means.

14. A pump system for supplying variable volumes of fluid in accordance with demand comprising the following combinations: first and second relatively movable pumping members defining a variable volume pumping chamber, drive means for moving one of said first and second pumping members in one direction relative to the other on a pumping stroke and permitting relative movement therebetween on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chamber on a pumping stroke, a source of charging fluid under a substantially constant pressure, first valve means for establishing and controlling fluid flow between said source and said pumping chamber, first biasing means operable on said first valve means for decreasing fluid flow from said source to said pumping chamber as said discharge pressure increases, second biasing means operable on said first valve means for acting in opposition to said first biasing means, actuation means operable on said first valve means to act in opposition to said second biasing means for rapidly decreasing fluid flow from said source to said pumping chamber when said discharge pressure reaches a predetermined maximum, dampening means connected to said first valve means for controlling the rate at which said valve means increases and de creases fluid flow from said source to said pumping chamber, and second valve means connected to said first valve means to override the effect of said dampening means for allowing said first valve means to rapidly increase said fluid flow from said source to said pumping chamber when said discharge pressure falls below a predetermined maximum.

15. A system for supplying variable volumes of fluid in accordance with demand comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving one of said members in one direction on a pumping stroke and permitting relative movement therebetween in an opposite direction on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chambers on pumping strokes thereof, a source of charging fluid under a substantially constant charging pressure, metering valve means having a plurality of inlet ports respectively communicating with respective ones of said pumping chambers and said source, said metering valve means being movable between first and second positions to open and close respectively said ports for supplying an independent .and uniform amount of fluid to each respective chamber, said metering valve having first, second and third operating areas, said first area being in communication with said discharge pressure for biasing said metering valve means toward said second position, biasing means acting against said second area for urging asid valve means toward said first position, said third area being disposed intermediate said first and second areas, and actuation means communicating said third area with said discharge means to supply fluid pressure to said third area when said discharge pressure exceeds a predetermined maximum for positively moving said valve means toward said second position to decrease source fluid flow to said respective pumping chambers.

16. The system according to claim 15 further comprising a dampening means in fluid communication with said third area and said source to restrict fluid flow therebetween for dampening oscillations of said metering valve.

17. The system according to claim 16 in which said dampening means includes a relief valve means for releasing fluid pressure above a predetermined value acting against said third area and communicating said fluid pressure with said source whereby said metering valve may rapidly move toward said first position.

18. A variable displacement pumping mechanism comprising a cylinder block including a plurality of spaced radially arranged cylinders each having an inner end opening into a drive chamber, a plurality of pump pistons respectively reciprocably mounted in said cylinders and each having an inner end projecting into said drive chamber and an outer end cooperable with a respective cylinder to form a plurality of variable volume pumping chambers, rotatable drive means in said drive chamber progressively engageable with said inner ends of said pump pistons to drive said pistons radially outward on pumping strokes and permitting independent inward movement of said pistons on intake strokes, discharge means communicating with said pumping chambers for receiving fluid therefrom at a discharge pressure on pumping strokes, said cylinder block having a first valve chamber, a metering valve means movably disposed between first and second positions in said first valve chamber, a source of charging fluid under a substantially constant charging pressure in communication with said first valve chamber, said metering valve means having a body member with a plurality of spaced radially arranged ports respectively communicating with respective ones of said pumping chambers to relatively decrease and increase the volume of flow to meter a predetermined variable volume of charging fluid to each of said respective pumping chambers on the intake strokes thereof as said metering valve means moves between said first and second positions, piston means disposed in said first valve chamber, said piston means movable to and abuttable with said body member, first and second opposed operating areas respectively on said body member and said piston means, said first area being in fluid communication with said discharge means for urging said metering valve means toward said second position, biasing means acting against said second area for urging said metering valve means toward said first position, said body member having a third operating area opposed to said first operating area, relief valve means in fluid communication with said third operating area and said discharge means for operating automatically in response to a pressure in excess of a predetermined maximum in said discharge means to connect the latter with said third operating area to positively move said body member toward said second position, dampening means having a two-way flow restriction therein in communication with said third area and said source of charging fluid for dampening oscillation of said body member in moving between said first and second positions respectively, and said dampening means further being operable automatically in response to a pressure acting on said third area in excess of a predetermined amount to allow fluid to by-pass said restriction for rapid movement of said body member toward said first position.

19. A pump system for supplying variable volumes of fluid in accordance with demand comprising a pump body, at least one pair of first and second relatively movable pumping members defining a variable volume pumping chamber within said pump body, drive means mounted in said pump body for moving one of said first and second pumping members relative to the other on a pumping stroke and permitting relative movement therebetween on an intake stroke, discharge means connected to said pump body for receiving fluid at discharge pressure from said pumping chamber on a pumping stroke, a source of charging fluid under a substantially constant pressure connected in fluid communication with said pumping chamber, a first valve means in a first valve chamber in said pump body and movable in a first direction to increase fluid flow from said source to said pumping chamber and movable in a second direction to decrease said fluid flow, said first valve means comprising a piston and a valve member normally in abutting relationship with one another, first biasing means establishing fluid communication between said discharge means and a first end of said piston for urging said piston against said valve member to move said valve member in said second direction, second biasing means acting on a first end of said valve member for urging said valve member against said piston, and actuation means for connecting in fluid communication said discharge means and the second end of said valve member abutting said piston for rapidly moving said valve member in said second direction when said discharge pressure reaches a predetermined maximum.

20. A pump system according to claim 19 in which said first biasing means includes a modulating valve means for supplying pressure to said first end of said piston in proportion to said discharge pressure.

21. A pump system according to claim 19 in which said second biasing means comprises a spring means.

22. A pump system according to claim 19 in which said actuation means comprises a relief valve for allowing discharge fluid to act against said second end of said valve member when said discharge fluid pressure reaches a predetermined maximum, and a dampening orifice to control the flow of fluid from said relief valve to said second end of said valve member.

23. A pump system according to claim 19 further including a restricted fluid line connecting said first end of saidpiston and said first end of said valve member.

24. A pump system according to claim 19 in Which said first biasing means comprises a first fluid line for subjecting said first end of said piston directly to discharge pressure.

25. A pump system according to claim 24 in which there is an area difierential between said first end of said piston and said first end of said valve member, and said second biasing means comprises a second fluid line connecting said first end of said valve member directly to source pressure.

26. A pump system according to claim 19 further comprising a second valve means in fluid communication with said first end of said valve member for releasing fluid when the fluid pressure acting thereagainst exceeds a predetermined maximum.

27. A pump system according to claim 19 in which said actuation means comprises a fluid line connecting said discharge means with said second end of said valve member, and a relief valve connected to said fluid line for allowing fluid flow to said second end of said valve member when said discharge pressure reaches said predetermined maximum.

28. A pump system according to claim 27 further comprising a dampening means for controlling the rate of movement of said valve member.

29. A pump system according to claim 28 in which said dampening means comprises a dampening valve having a restriction therein a fluid line connecting said second end of said valve member with said first end of said valve member whereby oscillations of said valve member are dampened.

30. A pump system according to claim 28 further com prising a quick recovery valve means communicating with discharge fluid pressure and disposed in a fluid line con-.

necting said second end of said valve member with said first end thereof for allowing fluid acting against said second end of said valve member to flow to said first end of said valve member when said discharge pressure falls below a predetermined minimum.

31. A pump system according to claim 28 further including a secondary relief valve means connected in fluid communication respectively with said second end of said valve member and'said first end of said valve member for allowing fluid supplied to said second end of said valve member by said actuation means in excess of that required to move said valve member in said second direction to flow to said first end of said valve member.

32. A pump system according to claim 28 in which said source of charging fluid is connected in fluid communication with a sump, and said dampening means comprises a dampening valve having a normally seated member which has a restricted passage therethrough and disposed in a fluid line connecting said second end of said valve member with sump.

33. A pump system according to claim 32 further comprising a spring means biasing said seated member closed for allowing said seated member to unseat when the pressure supplied said second end of said valve member exceeds a predetermined value to dump the excess fluid pressure to sump.

34. A variable displacement pumping mechanism comprising a cylinder block including a plurality of spaced radially arranged cylinders each having an inner end opening into a drive chamber, a plurality of pump pistons respectively reciprocably mounted in said cylinders and each having an inner end projecting into said drive chamber and an outer end cooperable with a respective cylinder to form a plurality of variable volume pumping chambers, drive means rotatably mounted in said drive chamber for successively engaging said inner ends of said pump pistons to drive the latter outward-1y on pumping strokes and permitting inward movement thereof on intake strokes, discharge means in fluid communication with said pumping chambers for receiving fluid under discharge pressure from said pumping chambers, a first check valve means for preventing fluid flow from said discharge means to said pumping chambers, said cylinder block having an inlet gallery a source of charging fluid under a substantially constant pressure connected in fluid communication with said gallery, said cylinder block having a valve chamber in fluid communication with said gallery, said cylinder block having a plurality of passages each leading fromsaid valve chamber to a respective pumping chamber, a check valve disposed in each of said passages for preventing fluid flow from each of said pumping chambers to said first valve chamber, a valve chamber having first and second ends slidably disposed in said valve chamber for movement in first and second directions, said valve member increasing fluid flow into said plurality of passages when moved in said first direction and decreasing fluid flow into said plurality of passages when moved in said second direction, whereby charging fluid pressure acts against said first end of said valve member, a piston having first and second ends slidably disposed in said cylinder block and in abutting relationship at said second end thereof with said second end of said valve member, modulating valve means disposed in said cylinder block in fluid communication with said discharge means and said first end of said piston for supplying fluid pressure to said first end of said piston in proportion to said discharge fluid pressure whereby said valve member is biased in said second direction thereby decreasing fluid flow from said gallery to said respective pumping chambers, spring means disposed in said first valve chamber for biasing said valve member in said first direction thereby increasing fluid flow from said gallery to said respective pumping chambers, relief valve means disposed in said cylinder block in fluid communication with said discharge means and said second end of said valve member to allow one-way fluid flow from said discharge means to said second end of said valve member when said discharge pressure exceeds a predetermined maximum for rapidly moving said valve member in said second direction, said relief valve means having a restrictive orifice adjacent thereto for restricting fluid flow from said relief valve to said second end of said body member, dampening valve means disposed in said cylinder block in fluid communication with said second end of said valve member and said gallery for restricting fluid flow therebetween whereby oscillations of said valve member are dampened, quick recovery valve means disposed in said cylinder block in fluid communication with said second end of said valve member and said gallery and responsive to discharge fluid pressure for allowing fluid to flow from said second end of said valve member to said gallery in an amount greater than passes through said dampening Valve means alone when said discharge pressure falls below a predetermined minimum, and secondary relief valve means disposed in said cylinder block in fluid communication .respectively with said second end of said valve member and said gallery for allowing fluid supplied to said second end of said valve member by said relief valve means in excess of that required to move said valve member in said second direction to flow to said gallery.

35. A pumping mechanism according to claim 34 further comprising a restricted fluid passage in said cylinder block between said first end of said piston and said gallery.

36. A variable displacement pumping mechanism comprising a cylinder block including a plurality of spaced radially arranged cylinders each having an inner end opening into a drive chamber, a plurality of pump pistons respectively reciprocably mounted in said cylinders and each having an inner end projecting into said drive chamber and an outer end cooperable with a respective cylinder to form a plurality of variable volume pumping chambers, drive means rotatably mounted on said drive means for successively engaging said inner ends of said pump pistons to drive the latter outwardly on pumping strokes and permitting inward movement on intake strokes, discharge means in fluid communication with said pumping chambers for receiving fluid under discharge pressure from said pumping chamber, a first check valve means for preventing fluid flow from said discharge means to said pumping chambers, said cylinder block having an inlet gallery, a source of charging fluid under a substantially constant pressure connected in fluid communication with said gallery, said source of charging fluid connected in fluid communication with a sump, said cylinder block having a valve chamber in fluid communication with said gallery, said cylinder block having a plurality of passages each leading from said valve chamber to a respective pumping chamber, a check valve disposed in each respective passage for preventing fluid flow from each of said pumping chambers to said first valve chamber, a valve member having first and second ends slidably disposed in said valve chamber for movement in first and second directions, said valve member decreasing fluid flow into said plurality of passages when moved in said second direction and increasing full fluid flow into said plurality of passages when moved in said first direction, a piston having first and second ends slidably disposed in said cylinder block and in abutting relationship at said second end thereof with said second end of said valve member, a fluid line connecting in fluid communication said first end of said piston with said discharge means for supplying discharge fluid pressure to said first end of said piston, said first end of said piston having an area less than the area of said first end of said valve member whereby discharge fluid pressure acts on said first end of said piston in opposition to charge fluid pressure acting on said first end of said valve member, relief valve means disposed in said cylinder block in fluid communication with said discharge means and said second end of said valve member to allow one-way fluid passage from said discharge means to said second end of said valve member when said discharge fluid pressure exceeds a predetermined maximum for rapidly moving said valve member in said second direction whereby fluid flow from said gallery to said respective pumping chambers is decreased, a dampening valve means disposed in said cylinder block in fluid communication with said second end of said valve member and said sump, said dampening valve means having a normally seated member having an orifice therethrough, a spring means biasing said seated member closed and allowing said seated member to open when the pressure supplied said second end of said valve member exceeds a predetermined value to dump the excess fluid to sump, and a second relief valve means in said cylinder block in fluid communication with said first end of said valve member and said sump for allowing fluid above a specified pressure to flow from said first side of said valve member to sump.

37. A system for supplying variable volumes of fluid in accordance with demand comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving one of said members in one direction on a pumping stroke and permitting relative movement therebetween in an opposite direction on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chambers on pumping strokes thereof, and means in fluid communication with said pumping chambers for simultaneously distributing equal a-mounts of fluid under a substantially constant pressure to said respective pumping chambers, said last-names means being responsive to said discharge pressure for varying the amount of fluid supplied to said chambers in response to changes in said discharge pressure.

38. A system for supplying variable volumes of fluid in accordance with demand comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving one of said members in one direction on a pumping stroke and permitting relative movement therebetween in an opposite direction on an intake stroke, discharge means for receiving fluid at discharge pressure from said pumping chambers on pumping strokes thereof, means in fluid communication with said pumping chambers and responsive to said discharge pressure for substantially simultaneously and equally distributing variable amounts of fluid under a substantially constant pressure to said respective pumping chambers, said last-named means being urged in a flow decreasing direction by discharge fluid and urged in a flow increasing direction by biasing means, and actuation means operable on said firstnamed means for rapidly decreasing flow to said chambers irrespective of said biasing means when said discharge pressure reaches a predetermined maximum.

39. A system for pumping variable volumes of fluid comprising a plurality of variable volume pumping chambers each including first and second relatively movable pumping members, drive means for moving said members in one direction relative to each other on a pumping stroke and permitting relative movement thereof in another direction on an intake stroke, a source of charging fluid, and means including distributing valve means communicating said source with said pumping chambers to distribute an equal volume of charging fluid to each sumping chamber on intake strokes thereof and being movable between first and second positions respectively relatively reducing and increasing the volume of distributed flow therethrough to respective ones of said pumping chambers to a substantially uniform extent.

40. The system according to claim 39 in which said distributing valve means comprises a plurality of inlet ports respectively communicating with respective ones of said pumping chambers, and a distributing valve member movable between said first and second positions respectively simultaneously closing and opening said ports to a substantially uniform extent.

References Cited by the Examiner UNITED STATES PATENTS 2,295,833 9/1942 Deschamps 103-40 2,433,220 12/1947 Huber 103-40 2,642,804 6/1953 Bowers 103-5 2,653,543 9/1953 Mott 103-5 2,709,339 5/1955 Edelman et a1. 103-5 2,845,029 '7/ 1958 Gratzmuller 103-40 MARK NEWMAN, Primary Examiner.

LAURENCE V. EFNER, DONLEY J. STOCKING,

Examiners.

W. I. KRAUSS, Assistant Examiner.

Claims

1. A SYSTEM FOR SUPPLYING VARIABLE VOLUMES OF FLUID IN ACCORDANCE WITH DEMAND COMPRISING A PLURALITY OF VARIABLE VOLUME PUMPING CHAMBERS EACH INCLUDING FIRST AND SECOND RELATIVELY MOVABLE PUMPING MEMBERS, DRIVE MEANS FOR MOVING SAID MEMBERS IN ONE DIRECTION RELATIVE TO EACH OTHER ON A PUMPING STROKE AND PERMITTING REALTIVE MOVEMENT THEREOF IN ANOTHER DIRECTION ON AN INTAKE STROKE, DISCHARGE MEANS FOR RECEIVING FLUID AT DISCHARGE PRESSURE FROM SAID PUMPING CHAMBERS ON PUMPING STROKES THEREOF, A SOURCE OF CHARGING FLUID UNDER A SUBSTANTIALLY CONSTANT CHARGING PRESSURE, AND MEANS INCLUDING PRESSURE RESPONSIVE METERING VALVE MEANS HAVING A PLURALITY OF INLET PORTS RESPECTIVELY COMMUNICATING SAID SOURCE WITH RESPECTIVE ONES OF SAID PUMPING CHAMBERS AND A METERING VALVE MEMBER VARIABLY MOVABLE BETWEEN FIRST AND SECOND POSITIONS RESPECTIVELY CLOSING AND OPENING SAID PORTS TO A SUBSTANTIALLY UNIFORM EXTENT TO METER EQUAL AMOUNTS OF CHARGING FLUID TO SAID RESPECTIVE PUMPING CHAMBERS ON INTAKE STROKES THEREOF, SAID VALVE MEMBER BEING VARIABLY MOVABLE BETWEEN SAID POSITIONS IN RESPONSE TO CHANGES IN SAID DISCHARGE PRESSURE.