CA1155771A - Hydrostatic adjustment device, more particularly a steering mechanism for motor-vehicles - Google Patents
Hydrostatic adjustment device, more particularly a steering mechanism for motor-vehiclesInfo
- Publication number
- CA1155771A CA1155771A CA000379673A CA379673A CA1155771A CA 1155771 A CA1155771 A CA 1155771A CA 000379673 A CA000379673 A CA 000379673A CA 379673 A CA379673 A CA 379673A CA 1155771 A CA1155771 A CA 1155771A
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- motor
- adjusting device
- control valve
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/16—Special measures for feedback, e.g. by a follow-up device
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/09—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by means for actuating valves
- B62D5/093—Telemotor driven by steering wheel movement
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Fluid-Pressure Circuits (AREA)
- Power Steering Mechanism (AREA)
- Servomotors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The specification describes a hydrostatic adjusting device, more particularly a steering mechanism for motor-vehicles, having an operating circuit comprising an adjusting motor, a control-valve connected thereto by leads and adjustable by means of an actuating element, and a feedback device reproducing the position of the adjusting motor by using a pressure-medium line, the feedback device acting in a direction opposite to that of the actuating element.
The specification describes a hydrostatic adjusting device, more particularly a steering mechanism for motor-vehicles, having an operating circuit comprising an adjusting motor, a control-valve connected thereto by leads and adjustable by means of an actuating element, and a feedback device reproducing the position of the adjusting motor by using a pressure-medium line, the feedback device acting in a direction opposite to that of the actuating element.
Description
Hydrostatic adjustin~ device, more particularly a steering mech~nism for motor-Yehicles.
_____ ______ __ ____________ _ ____________,, __ .
Tht- inventicn rel~tes to a hy~rost~tic adjusting device, nnre parti-cul~rlJ~ ~ ~teering rnech~nis~ for motor-vehicles, having an oper~tin~
circ~it com~ isin ~n adjusting motor, a control-vale connected thereto b~ k2~s ~nd adjustable b~ means of a actuating element, and a leedbac~
~evice re,;ro~ucin~the position of the adjusting r.lotor b~ using a pressure-mcdiu~ line, the said feedback device acting in a direction onposite tG
~:c~t oi tne seid actuztin~ element.
In one }.n.own adjustin~; device of this kind (German Pat~nt 12 93 029), the f ecdback device comprises an inte~rating ~ ~ea~r~g) motor ~Ihich is com~ined structurall~r ~;tith the control-valve and is driven by the pressure-mediu~ Ilowin~ to the said adjusting motor. Since t:.e adju~tin~
r~o~el:~ent of the integrating motor is proportional to the adjusting movernent of the adjusting motor, this provides the desired feedbac~-ef~ect, ~Jith no need for a mech~nical conrlection between the a~justing motor nn~ the control-valve- This has the advantaGe that t'ne adjusting l.lOtO need be conllected to the control-valve only by the prcssurc-me~ m lir.cs, ~;.;ich provi~es a ~xeat ~eal of freedom in arranging individual prt~ .iti-l ~djustin~ devQces oI this ~;ind, ho~7ever~ there eY~ists, un~er cer~in circu~st~r.ces (hi~h operatin~ pres~urcs, heavy ~Jear, ~tc. ) dan~cr of drift, i e the adju5t~nent of the integxating motor is not exactly proporti~.nal.
hlso kno~n (Ger~an ~S 26 29 113) are adjusting devices comprisin~ ~
purel~ mechanical feedbacl . Although these are drift-free, the control-"~
v~lve must be connected mechanically, not only with the actuating device,but also ~ith the adjusting motor. Thi8 results in considerable impair-ment of the overall design and assembly.
It is the purpose of th~ invention to provide a hydrostatic adjusting device o~ the type mentioned at the beginning hereo~, i.e. having a feed-back eIfected only by a pressure-medium line, such that leaks in tne system do not produce drift.
~ ccordin~ to the invention, this purpose is achieved in that the actuating element acts upon t~,e control-valve through a srring, and the adjusting motor acts upon ~the-pressure-relief valve through a spring, and in that the feedbac~ device comprises a hydrostatic ~eedbacl; circuit, the pressure in which is determined by the said pressure-relief valve and acts upon a pressure-surface on the said control-valve I~ this ~sign, the E~osition of the adjusting motor is converted, Wit~! tl-!e eid of a spring and a ~ressure-relief valve.into hydrostatic pres~ure. The control-valve assumes a position oi e~uilibriu~ whic.. is a function, on the one hand, of this hydrosthtic feedback pressure an~, on the other hand, of a s,3ring, the force of vJhich is determined by the position of the actuating element. Ieakage losses in the operati~g circuit play no part in this , since it is merely a matter of the position of the adjusting motor. Ieakare losses in the feedback circuit are also immaterial, sir,ce the feedback pressure determined by the pres~ure-relief valve i~ not in~luenced ti.erehy.
The advanta~es of a drift-free feedbac~ and flexible assembly are thus comblned.
The operating and feedback circuits may be completely separated from each other, each being sup~lied from its o~n source of pressure-medium.
Ho~ever, the feedback circuit and pressure-relief valve may be fitted between the inlet-e~d ol the control-valve and the tank. This makes it possible to manage with a single source of pressure-medium or pump. A
particl~larly lo~-power design is obtained by locating the ~eedback circuit an~ pressure-relie~ vaive between the outlet-end of the control-valve and the tank, s~nce in this way the pressure-fluid is use~ twice.
In one preferred exPmple of embodiment, the pressure-valve comprises, between inlet and outlet, t~o series-circuits of t~o chokes each, from the junction-l~oints of vihich, tr-e operating lines branch off, the chokes ~ithin each series-circuit, and the similar chokes of each series_circuit, ~eing adjustable in opposite directions. In this way, the position of the adjusting motor is given by a pressure-equilibrium. ~.ach adjustment oI the control-valves leads directly, i.e- ~ithout any lost motion, to an advusts~ent of tht adjusting motor. In addition to this this, pressu.e-llui~, at ~rl adeo,uate pressure-level, is always av~ilable at the out!ut fro~ the control-valve, in order to supply the feedback circuit.
~ particu.arly sim~le desi~n is obtained if the control-val.e comprises a piston, one end-face of which i~ loaded by the relev~ spring while the ot~er conEtitutes the pressure-surface exposed to the pressure in the leedback circuit.
It is also advantageous if- the spring on the ~ide fa~ing the adjust-ing motor and the actuating element rests upon a supporting piston de-fining a compensatin~-pre9sure chamber conlected to the ieedback circuit.
Thi~ prevents the feedback pressure ~rom having any effect Y~hatever upon the po~ition of the adjusting motor or of the actu&ting element.
In another confuguration of the invention, the act-uating element may be connected to a hand-pump, each connection to which is connected, via 1 1557~ 1 a non-returli valve open towards the source o~ pressure-me-dium~ to the pressure-side thereof and to the feed-5ide Gf the contr~l-valve. This ~n~-~ump ensures that the actuating elment may be adjusted, in normal operation, c-lmo5t without force, since the pressure-fluid supplied from thc pressur-medium source flows thrDugh the said han~-pump. However, there i9 an autOmatic~imit to the.speed of adjustment, if the pre~sure-medium source can no longer sup~ly sufIicient pressure-~luid;
in which case adequate force must be applied to the actuating element.
The hand-~pump may al80 be used as an emergency_pump.
~ ccording to one particularly favourable desi~n, the hand-pump delivers per nnit of travel at leasl the same amount of pressure-fluid as the adjusting motor per unit of travel. This allov~s emergency operation, in which even the feed-back circuit remains operatiYe.
It is also desirable for the pressure-side of the pressure-medium source to be conriected to the tank through a suction-non-return valve.
In thiC wa~, in the event o~ failure of the pressure-medium source, the s~id oUrCe is bridged by the said suction-non-return ~alve.
The invention i9 explained hereinaftc~ in greater detail in con-junction Y~ith the proferred example of embodiment illu~trated in th~-drawing attached hereto, in which the sole fi~ure is a circuit-dia~ram of an adjusting device according to the in7ention.
An operating circuit O comprises a pressure-medium so~rce 1 in t~e ~orm of a pum~, a control-valve 2 and and adjusting motor 3. The pump draws prc-ssure-Iluid irom a tank 4 ahd delivers it, from pre6sure-side 5, through two pairs of non-return valves 6,7 and 8,9, to inlet-si~e 10 of control-valve 2. The adjusting motor comprises a pislon 12 moving in a cylinder 11, pigton_rod 13 acting upon the mechanism to be adjusted, e.g. the wheels to be steered- The 8aid pi8to~ separates two operatlng ~ . v .. .. ....
cha~bers 14,15 from each other which are connected, thro~gh motor-leads 16,17, to motor connections 18,19 on control-valve 2.
Outlet-side 20 of the control-valve is no`t connected dircctly Y~it~.
i'and a tank-line 2 tank 4, but through a feedback circuit 21, 2 pressure-relief~~~ 7 ~eedback circuit 21 comprises a pre89ure-medium line 24 which connects to,ether a pressure-chamber 25 and a p~essure-chamber 26. ~ressure-relief valve 2? has a slide ~7 loaded on one side by a spring 28 ~hich bears upon a supporting piston 29 secured to piston-rod 13. ~eft-hand end-face 30 forms, in conjunction with a val~e-seat 31 inter-ral ~ith the housing, the cho~e-point o~ pressure-relief-valve 22. Slide 27 assumes a position of equilibrium which i8 dependent, on the one hcn~, upon the pôsition of adjusting motor 3 and the compression of sprinr 28 produced thereby and, on the other hand, upon force P1J which is e~ual to the siz.e of end-face 3L times pressure ~ in ~eed-back circuit 21.
Since pre~sure ~ is set by ~ressure-relief valve 22, this pressure is an accur~t~ insication o~ the position of adjusting motor 3. r Control-velve ~ comprises a pi~ton 32, one end of ~hich is 'oade~ by a sprir.g 33 be&rin6 upon a supporting piston 34 adapted to be displaced axisll~ by an actua~ting element 35. ~cting upon the other end ol piston 32 i~ ~ force P2 which is equal to the size of end-face 36 times pressure . As a result of this, the position of adjusting motor 3 is fed ba~k a~
pressure ~ to controi-valve 2.
Located behind supporting piston 29 i8 a compensationg chamber 37, and located behind compensating pi8ton 34 is a compensating chamber 38.
~oth chambers are connected by a compe~-~sating line 39 to the restorin~
circuit, in order to prevent any reactive effect of restoring pressure upon the position of the adju~ti~g motor or of the actuating element.
1 ~5577 1 ~ otor-cor.nections l~ls on con;rol-valv- 2 run from annular grooves 39,40. The piston comprises t~o lands (? shculders, collars) 41,42 which Pepar~te two inlet-side annular grooves 43,44 ~rom an outlet-side annular Frocve 4~ on the piston. This produces tVJo series-connected chokes A,3 an~ C,D, chokes A and ~ varying-jointly in one direction, and chokes an~ C varying 30intly in th~ other direction, as the piston is dis-placed.
~ ctuating element 35 is connected to a hand-pumo 46 co~prising a cylinder 47, a piston 48 and a piston-rod 49. One pressure chamber 50 is c~nnected to a point 51 between non-return valves 6,7, while the other pressuIe chamber 52 iS conr~ected to a point 53 betY~een non-return vzlves 8,9. ~oreover, pressure-side 5 of pressure-mediurn source 1 is conntcted, through a non-return valve 54, to tank 4.
The method OI operation of this arrangement is as follows.
~ ihen, durin~ normal operation, adJusting motor 3 is displace~ by a ~istance ~1, Spl ing 2~ is compressed accordingly. This produces a -position of eqvilibriu~,. of slide 27, in ~hich-:
Pl z Cl . xl, wherein Cl is the spring-constant of spring 28. Since pressure-relief v~lve 22 adjusts itself to this position of equilibrium, a feedback-pressure P, proportional to force Pl, is established in feedbac~ circuit 21. If the displacement of the actuating element is designate~ x2, this als~ produces a poaition of equilibrium of ~iston 32 in control-valve 2 in accordance with:
P2 = C2 . x2, wherein C2 is the spring-constant of spring 30.
If piston-rod 49is mo~ed to the left by actuating ele'ent 35, the pressure in motor-connection 19 rises while that in motor-connection 1&
1 ~5577~
falls.This causefi the piston in servo-motor 3 to move to the left, com-pressin~ spring 28 and increasing feedback pressure ~. This restores ~iston 3~ of control-valve 2, against the force of spring 33, to the central position. The same a~plies if actuating element 35 is moved to the right. The chan~es in travel are ~overned by tile speed-ratio of the apparatus. Inciuded in this speed-ratio are the spring-constants of prings 28 and 33 and the areas of end-faces 30 and 36. In this connection, any leakage losses in feedback-circuit 21 are without significance.
If it is noY~ assumed that a disturbing force S acts, from t-~le outside, upon adjusting motor 3, piston-rod 13 will be shifted slightly to the left. 1.8 a result of this, feedbac~lpressure ~ rises and moves piston 32 sli~htly to the right. The resu~t of this is that the pressure in operating chamber 14 rises, until disturbing fGrce S is compensate~ fo~, If this produces leakage along piston 12, thi~ is immaterial, since pressure-medium source 1 sup~lies an appropriate amount of fluid and feedback-pressure ~ is not affected. If actuating element 35 i8 ad-juEted and a disturning force S acts Eimultansously , the two previously ~ecribe~ ~unctions are superimpo~ed over each other in the correct ~irection.
Wher servo-mQtGr 3 is adjusted, the pressure-medium sup~,lied divides into one part which pa8ses directly through the chokes to outle~ æide 20 and another part which passes through the said motor to the outlet-side. In any case, sufficient pressure-medium to produce feedbacX-pressure ~ is available in feedback circuit 21. ~ ;
The move~ient of actuating element 35 is suFported by hand-pump 46 since, ~hen piston 48 is displ6ced, pressure-medium source 1, supplies fluid to the suction-6ide, whereas the pres6ure-fluid from the pressure-I
side of the hand-pump passes to pressure-side 10 of control-valve 2.
Hand~pump 46 is loaded only when actuating element 35 i9 moved so fast th&t the amount of pres~ure-fluid available from pressure-medium ource 1 is no longer sufficient, and increased resistance will be felt ~t the ~aid actuating element. Irhis provides the driver of a vehicle, for example, viith important information that the syste~ is being ad-justed too quickly since, in the case of a di9placement to the right, for example, if the hand-pump delivers a larger amount of pressure-fluid than pressure-medium source 1, the pressure at point 5 and in operating chamber 50 dro~s, whereas the pressure in operating chamber ~2 is held to to a level predetermined by the external loadin~ of the system. ~or this reason, non-re~urn valves 7,~ are closed at this time. If the pressure at point 5 drops below tank-pressure, pressure-fluid will be dra~n through non-return valve 54.
A special case in the la9t-considered operation is emergency-contr i.e. when pressure-mediu~ source 1 fail9 to deliver any pre~sure--~luid.
In this case, hand~pump 46 providea all of the pov~er. Pressure-fluid is dra-,n t~rou~h non-return valve 54 and i9 released through non-return valve~ 7, 5. If the ~eedback-cirouit i8 to operate correctly un~er theEe conditions, the hand-pumo must dis~lace an amount of fluid at lea~t as ~reat as that displa ed by piston 12 in ad3usting motor 3. In this way, feedback-control is maintained, at lea~t approximately, even during emer~ency operation.
In the dra~Jing, the adjustin~ deYice according to the invention is described in connection with movements of translation, but designs may also be used in wLich movement~ or rotation, or combinations of rotetion and translation, ariRe. ~or example, the adju~ting motor muy act upon .~.
1 ~55771 the track-rod of a steering mechanism, while the pressure-relief valve is fitted to the relevant kingpin, so that the adjustment is carried out in rotation.
It is also possible to arrange feedback circuit 21 in parallel with operating circuit 1, i.e. to branch it off from pressure side 10 of control valve 2. Moreover, feedback circuit 21 may also be provided with its own pump.
`~
sd/ ~ 9 . "' ,
_____ ______ __ ____________ _ ____________,, __ .
Tht- inventicn rel~tes to a hy~rost~tic adjusting device, nnre parti-cul~rlJ~ ~ ~teering rnech~nis~ for motor-vehicles, having an oper~tin~
circ~it com~ isin ~n adjusting motor, a control-vale connected thereto b~ k2~s ~nd adjustable b~ means of a actuating element, and a leedbac~
~evice re,;ro~ucin~the position of the adjusting r.lotor b~ using a pressure-mcdiu~ line, the said feedback device acting in a direction onposite tG
~:c~t oi tne seid actuztin~ element.
In one }.n.own adjustin~; device of this kind (German Pat~nt 12 93 029), the f ecdback device comprises an inte~rating ~ ~ea~r~g) motor ~Ihich is com~ined structurall~r ~;tith the control-valve and is driven by the pressure-mediu~ Ilowin~ to the said adjusting motor. Since t:.e adju~tin~
r~o~el:~ent of the integrating motor is proportional to the adjusting movernent of the adjusting motor, this provides the desired feedbac~-ef~ect, ~Jith no need for a mech~nical conrlection between the a~justing motor nn~ the control-valve- This has the advantaGe that t'ne adjusting l.lOtO need be conllected to the control-valve only by the prcssurc-me~ m lir.cs, ~;.;ich provi~es a ~xeat ~eal of freedom in arranging individual prt~ .iti-l ~djustin~ devQces oI this ~;ind, ho~7ever~ there eY~ists, un~er cer~in circu~st~r.ces (hi~h operatin~ pres~urcs, heavy ~Jear, ~tc. ) dan~cr of drift, i e the adju5t~nent of the integxating motor is not exactly proporti~.nal.
hlso kno~n (Ger~an ~S 26 29 113) are adjusting devices comprisin~ ~
purel~ mechanical feedbacl . Although these are drift-free, the control-"~
v~lve must be connected mechanically, not only with the actuating device,but also ~ith the adjusting motor. Thi8 results in considerable impair-ment of the overall design and assembly.
It is the purpose of th~ invention to provide a hydrostatic adjusting device o~ the type mentioned at the beginning hereo~, i.e. having a feed-back eIfected only by a pressure-medium line, such that leaks in tne system do not produce drift.
~ ccordin~ to the invention, this purpose is achieved in that the actuating element acts upon t~,e control-valve through a srring, and the adjusting motor acts upon ~the-pressure-relief valve through a spring, and in that the feedbac~ device comprises a hydrostatic ~eedbacl; circuit, the pressure in which is determined by the said pressure-relief valve and acts upon a pressure-surface on the said control-valve I~ this ~sign, the E~osition of the adjusting motor is converted, Wit~! tl-!e eid of a spring and a ~ressure-relief valve.into hydrostatic pres~ure. The control-valve assumes a position oi e~uilibriu~ whic.. is a function, on the one hand, of this hydrosthtic feedback pressure an~, on the other hand, of a s,3ring, the force of vJhich is determined by the position of the actuating element. Ieakage losses in the operati~g circuit play no part in this , since it is merely a matter of the position of the adjusting motor. Ieakare losses in the feedback circuit are also immaterial, sir,ce the feedback pressure determined by the pres~ure-relief valve i~ not in~luenced ti.erehy.
The advanta~es of a drift-free feedbac~ and flexible assembly are thus comblned.
The operating and feedback circuits may be completely separated from each other, each being sup~lied from its o~n source of pressure-medium.
Ho~ever, the feedback circuit and pressure-relief valve may be fitted between the inlet-e~d ol the control-valve and the tank. This makes it possible to manage with a single source of pressure-medium or pump. A
particl~larly lo~-power design is obtained by locating the ~eedback circuit an~ pressure-relie~ vaive between the outlet-end of the control-valve and the tank, s~nce in this way the pressure-fluid is use~ twice.
In one preferred exPmple of embodiment, the pressure-valve comprises, between inlet and outlet, t~o series-circuits of t~o chokes each, from the junction-l~oints of vihich, tr-e operating lines branch off, the chokes ~ithin each series-circuit, and the similar chokes of each series_circuit, ~eing adjustable in opposite directions. In this way, the position of the adjusting motor is given by a pressure-equilibrium. ~.ach adjustment oI the control-valves leads directly, i.e- ~ithout any lost motion, to an advusts~ent of tht adjusting motor. In addition to this this, pressu.e-llui~, at ~rl adeo,uate pressure-level, is always av~ilable at the out!ut fro~ the control-valve, in order to supply the feedback circuit.
~ particu.arly sim~le desi~n is obtained if the control-val.e comprises a piston, one end-face of which i~ loaded by the relev~ spring while the ot~er conEtitutes the pressure-surface exposed to the pressure in the leedback circuit.
It is also advantageous if- the spring on the ~ide fa~ing the adjust-ing motor and the actuating element rests upon a supporting piston de-fining a compensatin~-pre9sure chamber conlected to the ieedback circuit.
Thi~ prevents the feedback pressure ~rom having any effect Y~hatever upon the po~ition of the adjusting motor or of the actu&ting element.
In another confuguration of the invention, the act-uating element may be connected to a hand-pump, each connection to which is connected, via 1 1557~ 1 a non-returli valve open towards the source o~ pressure-me-dium~ to the pressure-side thereof and to the feed-5ide Gf the contr~l-valve. This ~n~-~ump ensures that the actuating elment may be adjusted, in normal operation, c-lmo5t without force, since the pressure-fluid supplied from thc pressur-medium source flows thrDugh the said han~-pump. However, there i9 an autOmatic~imit to the.speed of adjustment, if the pre~sure-medium source can no longer sup~ly sufIicient pressure-~luid;
in which case adequate force must be applied to the actuating element.
The hand-~pump may al80 be used as an emergency_pump.
~ ccording to one particularly favourable desi~n, the hand-pump delivers per nnit of travel at leasl the same amount of pressure-fluid as the adjusting motor per unit of travel. This allov~s emergency operation, in which even the feed-back circuit remains operatiYe.
It is also desirable for the pressure-side of the pressure-medium source to be conriected to the tank through a suction-non-return valve.
In thiC wa~, in the event o~ failure of the pressure-medium source, the s~id oUrCe is bridged by the said suction-non-return ~alve.
The invention i9 explained hereinaftc~ in greater detail in con-junction Y~ith the proferred example of embodiment illu~trated in th~-drawing attached hereto, in which the sole fi~ure is a circuit-dia~ram of an adjusting device according to the in7ention.
An operating circuit O comprises a pressure-medium so~rce 1 in t~e ~orm of a pum~, a control-valve 2 and and adjusting motor 3. The pump draws prc-ssure-Iluid irom a tank 4 ahd delivers it, from pre6sure-side 5, through two pairs of non-return valves 6,7 and 8,9, to inlet-si~e 10 of control-valve 2. The adjusting motor comprises a pislon 12 moving in a cylinder 11, pigton_rod 13 acting upon the mechanism to be adjusted, e.g. the wheels to be steered- The 8aid pi8to~ separates two operatlng ~ . v .. .. ....
cha~bers 14,15 from each other which are connected, thro~gh motor-leads 16,17, to motor connections 18,19 on control-valve 2.
Outlet-side 20 of the control-valve is no`t connected dircctly Y~it~.
i'and a tank-line 2 tank 4, but through a feedback circuit 21, 2 pressure-relief~~~ 7 ~eedback circuit 21 comprises a pre89ure-medium line 24 which connects to,ether a pressure-chamber 25 and a p~essure-chamber 26. ~ressure-relief valve 2? has a slide ~7 loaded on one side by a spring 28 ~hich bears upon a supporting piston 29 secured to piston-rod 13. ~eft-hand end-face 30 forms, in conjunction with a val~e-seat 31 inter-ral ~ith the housing, the cho~e-point o~ pressure-relief-valve 22. Slide 27 assumes a position of equilibrium which i8 dependent, on the one hcn~, upon the pôsition of adjusting motor 3 and the compression of sprinr 28 produced thereby and, on the other hand, upon force P1J which is e~ual to the siz.e of end-face 3L times pressure ~ in ~eed-back circuit 21.
Since pre~sure ~ is set by ~ressure-relief valve 22, this pressure is an accur~t~ insication o~ the position of adjusting motor 3. r Control-velve ~ comprises a pi~ton 32, one end of ~hich is 'oade~ by a sprir.g 33 be&rin6 upon a supporting piston 34 adapted to be displaced axisll~ by an actua~ting element 35. ~cting upon the other end ol piston 32 i~ ~ force P2 which is equal to the size of end-face 36 times pressure . As a result of this, the position of adjusting motor 3 is fed ba~k a~
pressure ~ to controi-valve 2.
Located behind supporting piston 29 i8 a compensationg chamber 37, and located behind compensating pi8ton 34 is a compensating chamber 38.
~oth chambers are connected by a compe~-~sating line 39 to the restorin~
circuit, in order to prevent any reactive effect of restoring pressure upon the position of the adju~ti~g motor or of the actuating element.
1 ~5577 1 ~ otor-cor.nections l~ls on con;rol-valv- 2 run from annular grooves 39,40. The piston comprises t~o lands (? shculders, collars) 41,42 which Pepar~te two inlet-side annular grooves 43,44 ~rom an outlet-side annular Frocve 4~ on the piston. This produces tVJo series-connected chokes A,3 an~ C,D, chokes A and ~ varying-jointly in one direction, and chokes an~ C varying 30intly in th~ other direction, as the piston is dis-placed.
~ ctuating element 35 is connected to a hand-pumo 46 co~prising a cylinder 47, a piston 48 and a piston-rod 49. One pressure chamber 50 is c~nnected to a point 51 between non-return valves 6,7, while the other pressuIe chamber 52 iS conr~ected to a point 53 betY~een non-return vzlves 8,9. ~oreover, pressure-side 5 of pressure-mediurn source 1 is conntcted, through a non-return valve 54, to tank 4.
The method OI operation of this arrangement is as follows.
~ ihen, durin~ normal operation, adJusting motor 3 is displace~ by a ~istance ~1, Spl ing 2~ is compressed accordingly. This produces a -position of eqvilibriu~,. of slide 27, in ~hich-:
Pl z Cl . xl, wherein Cl is the spring-constant of spring 28. Since pressure-relief v~lve 22 adjusts itself to this position of equilibrium, a feedback-pressure P, proportional to force Pl, is established in feedbac~ circuit 21. If the displacement of the actuating element is designate~ x2, this als~ produces a poaition of equilibrium of ~iston 32 in control-valve 2 in accordance with:
P2 = C2 . x2, wherein C2 is the spring-constant of spring 30.
If piston-rod 49is mo~ed to the left by actuating ele'ent 35, the pressure in motor-connection 19 rises while that in motor-connection 1&
1 ~5577~
falls.This causefi the piston in servo-motor 3 to move to the left, com-pressin~ spring 28 and increasing feedback pressure ~. This restores ~iston 3~ of control-valve 2, against the force of spring 33, to the central position. The same a~plies if actuating element 35 is moved to the right. The chan~es in travel are ~overned by tile speed-ratio of the apparatus. Inciuded in this speed-ratio are the spring-constants of prings 28 and 33 and the areas of end-faces 30 and 36. In this connection, any leakage losses in feedback-circuit 21 are without significance.
If it is noY~ assumed that a disturbing force S acts, from t-~le outside, upon adjusting motor 3, piston-rod 13 will be shifted slightly to the left. 1.8 a result of this, feedbac~lpressure ~ rises and moves piston 32 sli~htly to the right. The resu~t of this is that the pressure in operating chamber 14 rises, until disturbing fGrce S is compensate~ fo~, If this produces leakage along piston 12, thi~ is immaterial, since pressure-medium source 1 sup~lies an appropriate amount of fluid and feedback-pressure ~ is not affected. If actuating element 35 i8 ad-juEted and a disturning force S acts Eimultansously , the two previously ~ecribe~ ~unctions are superimpo~ed over each other in the correct ~irection.
Wher servo-mQtGr 3 is adjusted, the pressure-medium sup~,lied divides into one part which pa8ses directly through the chokes to outle~ æide 20 and another part which passes through the said motor to the outlet-side. In any case, sufficient pressure-medium to produce feedbacX-pressure ~ is available in feedback circuit 21. ~ ;
The move~ient of actuating element 35 is suFported by hand-pump 46 since, ~hen piston 48 is displ6ced, pressure-medium source 1, supplies fluid to the suction-6ide, whereas the pres6ure-fluid from the pressure-I
side of the hand-pump passes to pressure-side 10 of control-valve 2.
Hand~pump 46 is loaded only when actuating element 35 i9 moved so fast th&t the amount of pres~ure-fluid available from pressure-medium ource 1 is no longer sufficient, and increased resistance will be felt ~t the ~aid actuating element. Irhis provides the driver of a vehicle, for example, viith important information that the syste~ is being ad-justed too quickly since, in the case of a di9placement to the right, for example, if the hand-pump delivers a larger amount of pressure-fluid than pressure-medium source 1, the pressure at point 5 and in operating chamber 50 dro~s, whereas the pressure in operating chamber ~2 is held to to a level predetermined by the external loadin~ of the system. ~or this reason, non-re~urn valves 7,~ are closed at this time. If the pressure at point 5 drops below tank-pressure, pressure-fluid will be dra~n through non-return valve 54.
A special case in the la9t-considered operation is emergency-contr i.e. when pressure-mediu~ source 1 fail9 to deliver any pre~sure--~luid.
In this case, hand~pump 46 providea all of the pov~er. Pressure-fluid is dra-,n t~rou~h non-return valve 54 and i9 released through non-return valve~ 7, 5. If the ~eedback-cirouit i8 to operate correctly un~er theEe conditions, the hand-pumo must dis~lace an amount of fluid at lea~t as ~reat as that displa ed by piston 12 in ad3usting motor 3. In this way, feedback-control is maintained, at lea~t approximately, even during emer~ency operation.
In the dra~Jing, the adjustin~ deYice according to the invention is described in connection with movements of translation, but designs may also be used in wLich movement~ or rotation, or combinations of rotetion and translation, ariRe. ~or example, the adju~ting motor muy act upon .~.
1 ~55771 the track-rod of a steering mechanism, while the pressure-relief valve is fitted to the relevant kingpin, so that the adjustment is carried out in rotation.
It is also possible to arrange feedback circuit 21 in parallel with operating circuit 1, i.e. to branch it off from pressure side 10 of control valve 2. Moreover, feedback circuit 21 may also be provided with its own pump.
`~
sd/ ~ 9 . "' ,
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A hydrostatic adjusting device, more particularly a steering mechanism for motor vehicles, the said device having an operating circuit comprising an adjusting motor, a control valve connected thereto by operating lines and adjustable by means of an actuating element, and a feedback device reproducing the position of the adjusting motor by means of a pressure-medium line, the said feedback device acting in a direction opposite to that of the said actuating element, characterized in that the actuating element acts upon the control valve through a first spring, while the adjusting motor acts upon a pressure relief valve through a second spring; and in that the feedback device comprises a hydrostatic feedback circuit, the pressure (p) in which is determined by the said pressure relief valve and acts upon a pressure surface on the said control valve.
2. An adjusting device according to claim 1, characterized in that the feedback circuit, and the pressure relief valve, are located between the inlet-side of the control valve and a pressure-medium tank.
3. An adjusting device according to claim 1, characterized in that the feedback circuit and the pressure relief valve are located between the outlet side of the control valve and a pressure-medium tank.
4. An adjusting device according to one of claims 1 to 3, characterized in that the control valve comprises, between the inlet and outlet thereof, two series-connections each having two chokes from the junction points of which the operating lines branch off, the chokes within each series-circuit and the similar chokes of each series-circuit being adjustable in opposite directions.
5. An adjusting device according to claim 1 characterized in that the control valve comprises a piston, one end face of which is loaded by said first spring, while the other end face thereof constitutes the pressure surface exposed to the pressure (p) in the feedback circuit.
6. An adjusting device according to claim 1 characterized in that said springs, at the ends facing the adjusting motor and the actuating element respectively, bear upon supporting pistons defining compensating pressure chambers connected to the feedback circuit.
7. An adjusting device according to claim 1 characterized in that the actuating element is connected to a hand pump, said hand pump being connected through a non-return valve open towards a pressure-medium source, to the pressure side thereof, and to the inlet side of the control valve.
8. An adjusting device according to claim 7, characterized in that the hand pump displaces, per unit of travel, at least the same amount of pressure-medium as the adjusting motor per unit of travel.
9. An adjusting device according to claim 7 or 8 characterized in that the pressure side of the pressure-medium source is connected, through a suction non-return valve to a pressure-medium tank.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3024171A DE3024171C2 (en) | 1980-06-27 | 1980-06-27 | Hydrostatic control device, in particular steering device for vehicles |
| DEP3024171.5 | 1980-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1155771A true CA1155771A (en) | 1983-10-25 |
Family
ID=6105650
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379673A Expired CA1155771A (en) | 1980-06-27 | 1981-06-12 | Hydrostatic adjustment device, more particularly a steering mechanism for motor-vehicles |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5747001A (en) |
| CA (1) | CA1155771A (en) |
| DE (1) | DE3024171C2 (en) |
| DK (1) | DK149536C (en) |
| FR (1) | FR2485651A1 (en) |
| IT (1) | IT1145167B (en) |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1332089A (en) * | 1963-12-16 | |||
| FR1163246A (en) * | 1956-12-11 | 1958-09-23 | Creusot Forges Ateliers | Hydraulic servo-controlled remote control |
| US2984215A (en) * | 1958-11-25 | 1961-05-16 | Controller for fluid pressure operated devices | |
| DE1751528A1 (en) * | 1968-06-12 | 1971-07-08 | Messerschmitt Boelkow Blohm | Electro-hydraulic actuator with feedback |
| JPS4944197A (en) * | 1972-09-04 | 1974-04-25 | ||
| JPS4951494A (en) * | 1972-09-25 | 1974-05-18 | ||
| US4046059A (en) * | 1974-07-18 | 1977-09-06 | Willie Burt Leonard | Fluidic repeater |
| DE2629113C3 (en) * | 1976-06-29 | 1980-05-22 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Power steering for motor vehicles |
| DE2844055C2 (en) * | 1978-10-10 | 1983-12-01 | Mannesmann Rexroth GmbH, 8770 Lohr | Device for controlling the stroke delay of working cylinders, in particular of machine tools |
-
1980
- 1980-06-27 DE DE3024171A patent/DE3024171C2/en not_active Expired
-
1981
- 1981-06-12 CA CA000379673A patent/CA1155771A/en not_active Expired
- 1981-06-22 DK DK273181A patent/DK149536C/en not_active IP Right Cessation
- 1981-06-26 JP JP56098486A patent/JPS5747001A/en active Pending
- 1981-06-26 IT IT67890/81A patent/IT1145167B/en active
- 1981-06-26 FR FR8112678A patent/FR2485651A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| IT8167890A0 (en) | 1981-06-26 |
| DK273181A (en) | 1981-12-28 |
| IT1145167B (en) | 1986-11-05 |
| DK149536C (en) | 1987-03-30 |
| DE3024171C2 (en) | 1984-11-08 |
| DK149536B (en) | 1986-07-14 |
| DE3024171A1 (en) | 1982-01-21 |
| FR2485651B1 (en) | 1985-01-11 |
| FR2485651A1 (en) | 1981-12-31 |
| JPS5747001A (en) | 1982-03-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |