CA1246425A - Post-pressure-compensated unitary hydraulic valve - Google Patents
Post-pressure-compensated unitary hydraulic valveInfo
- Publication number
- CA1246425A CA1246425A CA000473619A CA473619A CA1246425A CA 1246425 A CA1246425 A CA 1246425A CA 000473619 A CA000473619 A CA 000473619A CA 473619 A CA473619 A CA 473619A CA 1246425 A CA1246425 A CA 1246425A
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- CA
- Canada
- Prior art keywords
- passage
- shuttle
- pressure
- check valve
- section
- 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
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/04—Control of fluid pressure without auxiliary power
- G05D16/10—Control of fluid pressure without auxiliary power the sensing element being a piston or plunger
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- 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
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
- F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
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- 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
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
- F15B13/08—Assemblies of units, each for the control of a single servomotor only
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/028—Controlling a pressure difference
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Fluid-Pressure Circuits (AREA)
- Multiple-Way Valves (AREA)
Abstract
Abstract A pressure compensated hydraulic valve is provided with a housing having a recriprocal spool for communicating hydraulic fluid to work ports Pressure compensating means is provided in the same housing with the valve and senses work port pressure by hydraulic fluid flow through the spool from the work port and creates a substantially fixed differ-ential pressure across the spool by controlling the pressure after the flow has passed through the spool.
Description
POST-PRESSURE-COMPENSATED UNITARY HYDRAULIC VALVE
Background And Summary The invention relates to pressure compensated hydraulic valves, wherein a fixed di~ferential pressure is maintained, to maintain a uniform flow rate.
In a hydraulic valve having a reciprocal spool for communicating hydraulic fluid to work ports, it is known to create a fixed differential pressure across the spool by controlling the pressure before the ~low has passed through the spool. For example in Wilke U.S. Patent 3,881,512, the hydraulic fluid is preconditioned before it flows across control spool 13 by an initial pressure compensating valve mechanism 15 which divides flow from inlet 18 to either feeder 20 or bypass 19 to keep the flow through work port 22 con-stant for any given position of spool 13 regardless of fluxuations in pump or load pressure.
~ In the present invention, a fixed differ-ential pressure is created by controlling pressure after hydraulic flo~ has passed through the spool~
The present invention evolved from cost re-duction efforts to minimize the number and complexity of parts, particularly those requiring machining. This is accomplished in part by marrying certain open flow circuit structure with pressure compensated circuit structure. In an open flow circuit, the flow rate changes in response to load pressure. Unitary open flow hydraulic valves are known having check valves in the same housing as the control spool, typically in the area of a bridge passage between work ports through the spool.
The present invention provides a unitary pressure compensated hydraulic valve, eliminating a ''i~'' ``
~'~469~5 separate dlscreet pressure compensatlng module. The pressure compensatlng means of the Inventlon Is In the same houslng as the control spool. Furthermore, the Inventlon enables known check valve structure and locatlon from open flow clrcultry to be applled and used In pressure compensatIng and shuttle clrcuits.
Thls facllltates economy o~ manufacture by enablIng use of exlstlng manufacturlng steps and assembly llne sequences for as much of the valve as posslble. The use of check valve structure for pressure compensatlng and shuttle clrcults Is further deslrable because It typlcally Invo~ves a less expenslve stamplng operatlon, as opposed to machlnlng or the llke.
Thus accordlng to one asepct thereof the present Inventlon provldes a closed center hydraullc control valve assembly comprlsed of a pluralIty of control valve sectlons ~olned In a bank and for use wlth a varla~le dlsplacement pump havlng output and pressure senslng ports, each of sald control valve sectlons havlng thereln a valve spool movable to an operatlng posltlon for selectlvely dlrectlng pressure fluld from a supply passage to one of a palr of workports vla a feeder passage havln~ upstream and downstream branches wlth a connectlng passage therebetween and wlth sald downstream feeder branch havlng a U-shaped brId~e passage havln~ a palr of le~s selectlvely respectively communlcable wlth sald workports by sald valve spool, the Improvement whlch comprlses a check valve blased In one dlrectlon toward a posltlon closlng sald connectlng passage and adapted to be moved In the opposlte dlrectlon to a posltlon openlng sald connectlng passage~ under force exerted on sald check valve In sald upstream feeder branch; meterlng means on sald spool for establIshlng a predetermlned pressure dlfferentlal across sald spool In sald operatlng posltlon; means for translatlng workport pressure Into force on sald check valve and also tendlng to move sald check valve In sald closlng one dlrectlon whereby sald check valve can act to hold a load In the absence of pressure In sald upstream feeder branch; means In sald houslng to communlcate ~orkport pressure wlth sald senslng Input ~4 port of sald variable dlsplacement pump havlng sald Olltput port connected wlth sald supply passage, whereby sald check valve acts as a pressure compensatlng valve and moves back and forth to vary the degree of communlcatlon between sald feeder branches in response to varlatlons In the forces of opposlng fluld pressures actlng thereon, to thereby malntaln sald predetermlned pressure dlfferentlal across sald spool and shuttle means operable to effect suJectlon of each sald check valve to t~le hlghest pressure o~ any sald workport In sald bank, sald shuttle means comprlslng 0 a senslng shuttle passage In each sa~d contro~s sectlon between the respective sald brldge passage and a shuttle check valve, and a through shuttle PaSsage between sald shuttle check valve of Its control sectlon and the shuttle check valve of the next control sectlon, such that If the workport pressure In sald brldge passage Is greater than the workport pressure In the brldge passage In the prevlous sectlon, then sald shuttle ~heck valve In the present sectlon closes the through shuttle passage of the prevlous sectlon and opens the senslng shuttle passage of the present sectlon to the through shuttle passage of the present sectlon such that the workport pressure In the brldge passage of the present sectlon Is passed through the senslng shuttle passage of the present sectlon to the next sectlon, and such that If the workport pressure In the bridge passage of the present sectlon Is less than the workport pressure In the brldge passage of the prevlous sectlon, then the shuttle check valve of the present sectlon closes the sensing shuttle passage o~ the present sectlon such that the workport pressure of the prevlous sectlon flows through the shuttle passage of the prevlous sectlon and Into the through shuttle passage of the present sectlon and Into the next sectlon, such that the hlghest workport pressure Is communlcated to sald pump and to the other slde of each of sald pressure compensatlng check valves In sald sectlons. Sultably sald valve spool Is axlally reclprocal In sald houslng, and whereln sald through shuttle passage Includes a flrst portlon ~xtendlng 3~ axlally In sald houslng from said houslng from sald shuttle check valve and a second portlon extendlng dlagonally transversely _ 2a -~`i ~Z~6g~2~i across sald houslng to sald shuttle check valves o~ the next sectlon, sald shuttle valves of the present and next sectlons belng substan~lally allgned along a lateral dlrectlon subs~ant~ally orthogonal to sald axls of axla~ reclproca-tlon of sald vaIve spool, saId flrst portlons of saId through shuttle passages of the present and next sectlons also belng substantlally allgned along sald lateral dlrectlon. Deslrably sald second portlon of sald through shuttle passage has flrst and second ends, ~he ~Irst end of sald second portlon of sald through shuttle passage of the present sectlon belng axlally offset from the second end of sald second portlon of sald through shuttle passage of the next sectlon and laterally allgned wlth an end of sald senslng shuttle passage o~ the next sectlon at sald shuttle check valve of sald next sectlon, the second end of sald second 1~ portlon of sald through shuttle passage of the present sectlon belng axlally offset from an end of sald sendlng shuttle passage of the present sectlon, and belng axlally offset from the flrst end of sald second portlon of sald through shuttle passage of the precedlng sectlon, sald end of sald senslng shuttle passage oF
the present sectlon belng laterally allgned wlth sald flrst end of sald second portlon of sald through shuttle passage of the precedlng sectlon at sald shuttle check valve of the present sectlon. Preferably sald senslng shuttie passage of each sald sectlon extends dlagonally transversely In sald houslng parallel to sald second portlon of sald through shuttle passage In Its respectlve sald sectlon.
In another aspect thereof the present Inventlon provldes a hydraullc control valve for use wlth a varlable dlsplacement pump havlng output and pressure senslng ports, comprlslng a houslng havïng thereln a valve spool movable In a bore to an operat7ng posltlon at whlch It dlrects pump output fluld from a pressure fluid supply passage In the bore to a workport characterlzed by: A means In the houslng provldlng a 3~ feeder passage havlng an Inlet branch whlch has Its orlgln In the bore to recelve supply pressure fluld ~rom the supply passage
Background And Summary The invention relates to pressure compensated hydraulic valves, wherein a fixed di~ferential pressure is maintained, to maintain a uniform flow rate.
In a hydraulic valve having a reciprocal spool for communicating hydraulic fluid to work ports, it is known to create a fixed differential pressure across the spool by controlling the pressure before the ~low has passed through the spool. For example in Wilke U.S. Patent 3,881,512, the hydraulic fluid is preconditioned before it flows across control spool 13 by an initial pressure compensating valve mechanism 15 which divides flow from inlet 18 to either feeder 20 or bypass 19 to keep the flow through work port 22 con-stant for any given position of spool 13 regardless of fluxuations in pump or load pressure.
~ In the present invention, a fixed differ-ential pressure is created by controlling pressure after hydraulic flo~ has passed through the spool~
The present invention evolved from cost re-duction efforts to minimize the number and complexity of parts, particularly those requiring machining. This is accomplished in part by marrying certain open flow circuit structure with pressure compensated circuit structure. In an open flow circuit, the flow rate changes in response to load pressure. Unitary open flow hydraulic valves are known having check valves in the same housing as the control spool, typically in the area of a bridge passage between work ports through the spool.
The present invention provides a unitary pressure compensated hydraulic valve, eliminating a ''i~'' ``
~'~469~5 separate dlscreet pressure compensatlng module. The pressure compensatlng means of the Inventlon Is In the same houslng as the control spool. Furthermore, the Inventlon enables known check valve structure and locatlon from open flow clrcultry to be applled and used In pressure compensatIng and shuttle clrcuits.
Thls facllltates economy o~ manufacture by enablIng use of exlstlng manufacturlng steps and assembly llne sequences for as much of the valve as posslble. The use of check valve structure for pressure compensatlng and shuttle clrcults Is further deslrable because It typlcally Invo~ves a less expenslve stamplng operatlon, as opposed to machlnlng or the llke.
Thus accordlng to one asepct thereof the present Inventlon provldes a closed center hydraullc control valve assembly comprlsed of a pluralIty of control valve sectlons ~olned In a bank and for use wlth a varla~le dlsplacement pump havlng output and pressure senslng ports, each of sald control valve sectlons havlng thereln a valve spool movable to an operatlng posltlon for selectlvely dlrectlng pressure fluld from a supply passage to one of a palr of workports vla a feeder passage havln~ upstream and downstream branches wlth a connectlng passage therebetween and wlth sald downstream feeder branch havlng a U-shaped brId~e passage havln~ a palr of le~s selectlvely respectively communlcable wlth sald workports by sald valve spool, the Improvement whlch comprlses a check valve blased In one dlrectlon toward a posltlon closlng sald connectlng passage and adapted to be moved In the opposlte dlrectlon to a posltlon openlng sald connectlng passage~ under force exerted on sald check valve In sald upstream feeder branch; meterlng means on sald spool for establIshlng a predetermlned pressure dlfferentlal across sald spool In sald operatlng posltlon; means for translatlng workport pressure Into force on sald check valve and also tendlng to move sald check valve In sald closlng one dlrectlon whereby sald check valve can act to hold a load In the absence of pressure In sald upstream feeder branch; means In sald houslng to communlcate ~orkport pressure wlth sald senslng Input ~4 port of sald variable dlsplacement pump havlng sald Olltput port connected wlth sald supply passage, whereby sald check valve acts as a pressure compensatlng valve and moves back and forth to vary the degree of communlcatlon between sald feeder branches in response to varlatlons In the forces of opposlng fluld pressures actlng thereon, to thereby malntaln sald predetermlned pressure dlfferentlal across sald spool and shuttle means operable to effect suJectlon of each sald check valve to t~le hlghest pressure o~ any sald workport In sald bank, sald shuttle means comprlslng 0 a senslng shuttle passage In each sa~d contro~s sectlon between the respective sald brldge passage and a shuttle check valve, and a through shuttle PaSsage between sald shuttle check valve of Its control sectlon and the shuttle check valve of the next control sectlon, such that If the workport pressure In sald brldge passage Is greater than the workport pressure In the brldge passage In the prevlous sectlon, then sald shuttle ~heck valve In the present sectlon closes the through shuttle passage of the prevlous sectlon and opens the senslng shuttle passage of the present sectlon to the through shuttle passage of the present sectlon such that the workport pressure In the brldge passage of the present sectlon Is passed through the senslng shuttle passage of the present sectlon to the next sectlon, and such that If the workport pressure In the bridge passage of the present sectlon Is less than the workport pressure In the brldge passage of the prevlous sectlon, then the shuttle check valve of the present sectlon closes the sensing shuttle passage o~ the present sectlon such that the workport pressure of the prevlous sectlon flows through the shuttle passage of the prevlous sectlon and Into the through shuttle passage of the present sectlon and Into the next sectlon, such that the hlghest workport pressure Is communlcated to sald pump and to the other slde of each of sald pressure compensatlng check valves In sald sectlons. Sultably sald valve spool Is axlally reclprocal In sald houslng, and whereln sald through shuttle passage Includes a flrst portlon ~xtendlng 3~ axlally In sald houslng from said houslng from sald shuttle check valve and a second portlon extendlng dlagonally transversely _ 2a -~`i ~Z~6g~2~i across sald houslng to sald shuttle check valves o~ the next sectlon, sald shuttle valves of the present and next sectlons belng substan~lally allgned along a lateral dlrectlon subs~ant~ally orthogonal to sald axls of axla~ reclproca-tlon of sald vaIve spool, saId flrst portlons of saId through shuttle passages of the present and next sectlons also belng substantlally allgned along sald lateral dlrectlon. Deslrably sald second portlon of sald through shuttle passage has flrst and second ends, ~he ~Irst end of sald second portlon of sald through shuttle passage of the present sectlon belng axlally offset from the second end of sald second portlon of sald through shuttle passage of the next sectlon and laterally allgned wlth an end of sald senslng shuttle passage o~ the next sectlon at sald shuttle check valve of sald next sectlon, the second end of sald second 1~ portlon of sald through shuttle passage of the present sectlon belng axlally offset from an end of sald sendlng shuttle passage of the present sectlon, and belng axlally offset from the flrst end of sald second portlon of sald through shuttle passage of the precedlng sectlon, sald end of sald senslng shuttle passage oF
the present sectlon belng laterally allgned wlth sald flrst end of sald second portlon of sald through shuttle passage of the precedlng sectlon at sald shuttle check valve of the present sectlon. Preferably sald senslng shuttie passage of each sald sectlon extends dlagonally transversely In sald houslng parallel to sald second portlon of sald through shuttle passage In Its respectlve sald sectlon.
In another aspect thereof the present Inventlon provldes a hydraullc control valve for use wlth a varlable dlsplacement pump havlng output and pressure senslng ports, comprlslng a houslng havïng thereln a valve spool movable In a bore to an operat7ng posltlon at whlch It dlrects pump output fluld from a pressure fluid supply passage In the bore to a workport characterlzed by: A means In the houslng provldlng a 3~ feeder passage havlng an Inlet branch whlch has Its orlgln In the bore to recelve supply pressure fluld ~rom the supply passage
- 2~ -~ ,~
whenever the valve spool Is In sald operatlng posltlon ~hereof, sald feeder passage havlng an outlet branch adJacent to the workport to be communlcated therewlth through the bore by the valve spool In Its sald operatlng posltlon; B. means In the houslng deflnlng a check valve chamber, one end portlon of whlch Is sltuated between sald branches of the feeder passage and to whlch the Inlet branch thereof opens to recelve supply pressure fluld therefrom; C. means In the houslng provldlng a connectlng passage to communlcate sald one end portlon of the check valve chamber wlth the outlet branch of the feeder passage and by whlch sald feeder passage branches are communlcable wlth one another;
D. a load holdlng check valve In sald chamber blased In a closlng dlrectlon toward a posl~lon In said one end portlon of Its chamber at whlch It blocks fluld flow to sald outlet branch of 1~ the feeder passage, sald chec~ valve belng movable In the openlng dlrectlon under force exerted thereon by pressure of supply fluld In the Inlet branch of the feeder passage to provlde for flow of such supply fluld to the outlet branch of the feeder passage; E.
means In the houslng for translatlng workport pressure Into force on sald check valve In opposltlon to sald valve openlng force and capable of movlng It In sald closlng dlrectlon whereby sald check valve can act to hold a load In the event of pressure drop In the Inlet branch of the feeder passage; and F. means In the houslng to communlcate workport pressure wlth sald senslng port of a varlable dlsplacement pump havlng Its output port connected wlth sald supply passage, whereby sald chec~ valve can act as a pressure compensatlng valve to move back and forth and thus vary the degree of communlcatlon between the feeder passage branches In response to Varlatlons In the opposlng fluld pressure forces actlng thereon. to thereby malntaln a predetermlnable dlfference In pressure between fluld In the suPply passage and that In the Inlet branch of the feeder passage. Sultably sald houslng Is provlded wlth two workports; the outlet branch of the feeder passage comprlses a U-shaped brldge passage whlch spans that portlon of the bore at whlch the supply passage and the orlgln of the feeder passage are located, sald brldge passage having a palr _ 2c -of legs selectlvely respectlvely communlcable wlth sald wor~ports by the valve spool; one of sald legs belng In communlcatlon wIth sald connectlng passage; and the check valve chamber and chec~
valve thereln belng substantlally embraced by ~he U-shaped brldge passage.
The present Inventlon wlll be Illustrated by reference to the accompanylng drawlngs. In whlch:-Flg. 1.is a sectlonal slde vlew of a valve constructed In accordance wlth the Inventlon; and Flg. 2 Is a sectlonal top vlew of the valve of Flg. 1.
Referrlng to Flg. 1, valve 2 Includes a houslng 4 havlng a reclprocal control spool 6 moveable left-rlght for communlcatlng hydraullc fluld to work ports 8 and 10. Spool 6 Is shown In the neutral posltlon, and brldge passage 12 Is vented to reservolr passage or tank 14 throu~h brldge vent passage 16 In the control spool as shown at dashed llne vent passages 16a,16b and 16c.
When spool 6 Is moved leftwardly by the operator, brldge vent passage 16 Is blocked, and brldge Passage 12 Is placed In communlcatlon wIth workport 8 through control spool passage 20, such that the workport pressure Is sensed In brldge passage 12 by _ Zd -~6~25 hydraulic fluid flow through the spool. This applied work port pressure pressurizes a pilot system for load sensing and pressure compensation.
Bridge passage 12 is in communication with a S sensing shuttle passage 22, FIG. 2. If the valve is a single section or monoblock valve, the hydraulic flow in passage 22 continues past shuttle check valve 24 and into crossing passage 26 and through-shuttle passage 28. If the valve is a multi-section valve, then a plurality of identical valve sections are aligned side by side, for example as shown cut away at 30 and 32.
If the work port pressure of central section 31 in sensing shuttle passage 22 is greater than the work port pressure in through-shuttle passage 34 of the lS previous section 30, then shuttle check valve 24 moves downwardly to close passage 34 and the higher pressure from passage 22 is communicated through crossing pas-sage 26 to through shuttle passage 28. If the work port pressure in sensing shuttle passage 22 of present ~ valve section 31 is less than the work port pressure in the through-shuttle passage 34 of the previous section 30, then shuttle check valve 24 moves upwardly to close passage 22 and enable the higher pressure in passage 34 to be communicated to through-shuttle passage 28.
Likewise, shuttle check valve 36 of the next section 32 operates to apply the higher pressure of through-shuttle passage 28 of the present section 31 and sens-ing shuttle passage 38 of the next section 32 to the through-shuttle passage 40 of next section 32. In this manner, the highest work port pressure of all the valve sections is communicated to a sense line 42 connected to the input 44 of hydraulic pump 46 and to a communi-cation passage 48 which extends through all of the valve sections, as shown through respective passages 50, 52 and 54.
~Z~25 . Transfer passage 52 communicates through cross passage 56 with a pressure compensating check valve 58, such as a spring biased poppet. The bottom side 60 of check valve 58 is thus applied with the pressure from passage 52, which is the highest work port pressure of the valve sections. The top side 62 of valve 58 is of the same area as the bottom side and thus the same pressure is applied in passage 64 above valve 58. Passage 64 around the top of valve 58 is a feeder passage which also has a section around spool 6, FIG. 1. The pressure in feeder passage 64 is thus the highest work port pressure of the multiple valve sec-tions.
The above noted description e~plains pressur-ization of the system in response to initial movement of spool 6. This pressurization occurs before metering notch or passage 66 in the spool and comes into commun-ication with feeder passsage 64.
Further leftward movement of spool 6 brings 2~ metering passage 66 into communication with feeder passage 64. Supply passage 68 then communicates with feeder passage 64 through metering passage 66.
Metering passage 70 and supply passage 72, effective during rightward movement of spool 6, are comparable.
~5 Supply passages 68 and 72 are supplied from pump ~6 which outputs hydraulic flow pressure on output 74 which is a predetermined amount greater than the flow pressure input to the pump at 44. Since the pressure at 44, FIGS. 1 and 2, is the highest work port pressure of the valve sections, the pressure in supply passages 68 and 72 is the noted predetermined amount greater than the highest work port pressure. As above noted, the initial pressurization of the system causes the pressure in feeder passage 64 to be the same as the highest work port pressure. There is thus a fixed ~Z~6~25i differential pressure across metering passage 66 from supply passage 68 to feeder passage 64.
Hydraulic fluid can flow from supply passage 68 through metering passage 66 to feeder passage 64.
Feeder passage 64, FIG. 2, communicates with the left side of bridge passage 12 through cross passage 76 and an orifice 78 opened by downward movement of pressure compensating check valve 58. The flow rate in feeder passage 64 is such as to provide sufficient fluid to ~ afford the same amount of pressure on the top side 62 as on the bottom side 60 of valve 58. Valve 58 can move up and down to control the size of orifice 78, such that should the load increase, causing work port pressure to increase r the shuttle system communicates 1~ the need for increased fluid to be delivered from the pump through the pressure compensating mechanism into the bridge and the work port until balance is achieved in the system. The fluid trans~erred into passage 76 flows through bridge 12 to the right side of the ~ latter, FIGo 1~ and through spool passage 20 to work port 8, to supply the additionally required fluid.
Load 80 is raised via outlet and inlet work ports 8 and 10 and their respective connection lines 82 and 84. Further leftward movement of spool 6 by the ~5 operator further raises load 80 by increasing the area of metering passage 66 which is exposed to feeder pas-sage 64. Flow rate is equal to the product of the area and the square root of the differential pressure.
Since the differential pressure across metering passage 66 is constant, flow rate is a direct linear function of the area of metering passage 66 which is in communi-cation with feeder passage 64. This area is increased during further leftward movement of spool 6, thus supplying more fluid and raising load 80. Standard pressure relief valves 86 and 88 are provided for the ~Z~6425 work ports and reservoir passage. A standard spring centering mechanism 90 is provided on the end of spool 6 Eor locating the latter's neutral positionO
whenever the valve spool Is In sald operatlng posltlon ~hereof, sald feeder passage havlng an outlet branch adJacent to the workport to be communlcated therewlth through the bore by the valve spool In Its sald operatlng posltlon; B. means In the houslng deflnlng a check valve chamber, one end portlon of whlch Is sltuated between sald branches of the feeder passage and to whlch the Inlet branch thereof opens to recelve supply pressure fluld therefrom; C. means In the houslng provldlng a connectlng passage to communlcate sald one end portlon of the check valve chamber wlth the outlet branch of the feeder passage and by whlch sald feeder passage branches are communlcable wlth one another;
D. a load holdlng check valve In sald chamber blased In a closlng dlrectlon toward a posl~lon In said one end portlon of Its chamber at whlch It blocks fluld flow to sald outlet branch of 1~ the feeder passage, sald chec~ valve belng movable In the openlng dlrectlon under force exerted thereon by pressure of supply fluld In the Inlet branch of the feeder passage to provlde for flow of such supply fluld to the outlet branch of the feeder passage; E.
means In the houslng for translatlng workport pressure Into force on sald check valve In opposltlon to sald valve openlng force and capable of movlng It In sald closlng dlrectlon whereby sald check valve can act to hold a load In the event of pressure drop In the Inlet branch of the feeder passage; and F. means In the houslng to communlcate workport pressure wlth sald senslng port of a varlable dlsplacement pump havlng Its output port connected wlth sald supply passage, whereby sald chec~ valve can act as a pressure compensatlng valve to move back and forth and thus vary the degree of communlcatlon between the feeder passage branches In response to Varlatlons In the opposlng fluld pressure forces actlng thereon. to thereby malntaln a predetermlnable dlfference In pressure between fluld In the suPply passage and that In the Inlet branch of the feeder passage. Sultably sald houslng Is provlded wlth two workports; the outlet branch of the feeder passage comprlses a U-shaped brldge passage whlch spans that portlon of the bore at whlch the supply passage and the orlgln of the feeder passage are located, sald brldge passage having a palr _ 2c -of legs selectlvely respectlvely communlcable wlth sald wor~ports by the valve spool; one of sald legs belng In communlcatlon wIth sald connectlng passage; and the check valve chamber and chec~
valve thereln belng substantlally embraced by ~he U-shaped brldge passage.
The present Inventlon wlll be Illustrated by reference to the accompanylng drawlngs. In whlch:-Flg. 1.is a sectlonal slde vlew of a valve constructed In accordance wlth the Inventlon; and Flg. 2 Is a sectlonal top vlew of the valve of Flg. 1.
Referrlng to Flg. 1, valve 2 Includes a houslng 4 havlng a reclprocal control spool 6 moveable left-rlght for communlcatlng hydraullc fluld to work ports 8 and 10. Spool 6 Is shown In the neutral posltlon, and brldge passage 12 Is vented to reservolr passage or tank 14 throu~h brldge vent passage 16 In the control spool as shown at dashed llne vent passages 16a,16b and 16c.
When spool 6 Is moved leftwardly by the operator, brldge vent passage 16 Is blocked, and brldge Passage 12 Is placed In communlcatlon wIth workport 8 through control spool passage 20, such that the workport pressure Is sensed In brldge passage 12 by _ Zd -~6~25 hydraulic fluid flow through the spool. This applied work port pressure pressurizes a pilot system for load sensing and pressure compensation.
Bridge passage 12 is in communication with a S sensing shuttle passage 22, FIG. 2. If the valve is a single section or monoblock valve, the hydraulic flow in passage 22 continues past shuttle check valve 24 and into crossing passage 26 and through-shuttle passage 28. If the valve is a multi-section valve, then a plurality of identical valve sections are aligned side by side, for example as shown cut away at 30 and 32.
If the work port pressure of central section 31 in sensing shuttle passage 22 is greater than the work port pressure in through-shuttle passage 34 of the lS previous section 30, then shuttle check valve 24 moves downwardly to close passage 34 and the higher pressure from passage 22 is communicated through crossing pas-sage 26 to through shuttle passage 28. If the work port pressure in sensing shuttle passage 22 of present ~ valve section 31 is less than the work port pressure in the through-shuttle passage 34 of the previous section 30, then shuttle check valve 24 moves upwardly to close passage 22 and enable the higher pressure in passage 34 to be communicated to through-shuttle passage 28.
Likewise, shuttle check valve 36 of the next section 32 operates to apply the higher pressure of through-shuttle passage 28 of the present section 31 and sens-ing shuttle passage 38 of the next section 32 to the through-shuttle passage 40 of next section 32. In this manner, the highest work port pressure of all the valve sections is communicated to a sense line 42 connected to the input 44 of hydraulic pump 46 and to a communi-cation passage 48 which extends through all of the valve sections, as shown through respective passages 50, 52 and 54.
~Z~25 . Transfer passage 52 communicates through cross passage 56 with a pressure compensating check valve 58, such as a spring biased poppet. The bottom side 60 of check valve 58 is thus applied with the pressure from passage 52, which is the highest work port pressure of the valve sections. The top side 62 of valve 58 is of the same area as the bottom side and thus the same pressure is applied in passage 64 above valve 58. Passage 64 around the top of valve 58 is a feeder passage which also has a section around spool 6, FIG. 1. The pressure in feeder passage 64 is thus the highest work port pressure of the multiple valve sec-tions.
The above noted description e~plains pressur-ization of the system in response to initial movement of spool 6. This pressurization occurs before metering notch or passage 66 in the spool and comes into commun-ication with feeder passsage 64.
Further leftward movement of spool 6 brings 2~ metering passage 66 into communication with feeder passage 64. Supply passage 68 then communicates with feeder passage 64 through metering passage 66.
Metering passage 70 and supply passage 72, effective during rightward movement of spool 6, are comparable.
~5 Supply passages 68 and 72 are supplied from pump ~6 which outputs hydraulic flow pressure on output 74 which is a predetermined amount greater than the flow pressure input to the pump at 44. Since the pressure at 44, FIGS. 1 and 2, is the highest work port pressure of the valve sections, the pressure in supply passages 68 and 72 is the noted predetermined amount greater than the highest work port pressure. As above noted, the initial pressurization of the system causes the pressure in feeder passage 64 to be the same as the highest work port pressure. There is thus a fixed ~Z~6~25i differential pressure across metering passage 66 from supply passage 68 to feeder passage 64.
Hydraulic fluid can flow from supply passage 68 through metering passage 66 to feeder passage 64.
Feeder passage 64, FIG. 2, communicates with the left side of bridge passage 12 through cross passage 76 and an orifice 78 opened by downward movement of pressure compensating check valve 58. The flow rate in feeder passage 64 is such as to provide sufficient fluid to ~ afford the same amount of pressure on the top side 62 as on the bottom side 60 of valve 58. Valve 58 can move up and down to control the size of orifice 78, such that should the load increase, causing work port pressure to increase r the shuttle system communicates 1~ the need for increased fluid to be delivered from the pump through the pressure compensating mechanism into the bridge and the work port until balance is achieved in the system. The fluid trans~erred into passage 76 flows through bridge 12 to the right side of the ~ latter, FIGo 1~ and through spool passage 20 to work port 8, to supply the additionally required fluid.
Load 80 is raised via outlet and inlet work ports 8 and 10 and their respective connection lines 82 and 84. Further leftward movement of spool 6 by the ~5 operator further raises load 80 by increasing the area of metering passage 66 which is exposed to feeder pas-sage 64. Flow rate is equal to the product of the area and the square root of the differential pressure.
Since the differential pressure across metering passage 66 is constant, flow rate is a direct linear function of the area of metering passage 66 which is in communi-cation with feeder passage 64. This area is increased during further leftward movement of spool 6, thus supplying more fluid and raising load 80. Standard pressure relief valves 86 and 88 are provided for the ~Z~6425 work ports and reservoir passage. A standard spring centering mechanism 90 is provided on the end of spool 6 Eor locating the latter's neutral positionO
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A closed center hydraulic control valve assembly comprised of a plurality of control valve sections joined in a bank and for use with a variable displacement pump having output and pressure sensing ports, each of said control valve sections having therein a valve spool movable to an operating position for selectively directing pressure fluid from a supply passage to one of a pair of work ports via a feeder passage having upstream and downstream branches with a connecting passage therebetween and with said downstream feeder branch having a U-shaped bridge passage having a pair of legs selectively respectively communicable with said workports by said valve spool, the improvement which comprises a check valve biased in one direction toward a position closing said connecting passage and adapted to be moved in the opposite direction to a position opening said connecting passage under force exerted on said check valve in said upstream feeder branch, metering means on said spool for establishing a predetermined pressure differential across said spool in said operating position; means for translating workport pressure into force on said check valve and also lending to move said check valve in said dosing one direction whereby said check valve can act to hold a load in the absence of pressure in said upstream feeder branch; means in said housing to communicate workport pressure with said sensing input port of said variable displacement pump having said output port connected with said supply passage, whereby said check valve acts as a pressure compensating valve and moves back and forth to vary the degree of communication between said feeder branches in response to variations in the forces of opposing fluid pressures acting thereon, to thereby maintain said predetermined pressure differential across said spool and shuttle means operable to effect subjection of each said check valve to the highest pressure of any said work port in said bank, said shuttle means comprising a sensing shuttle passage in each said controls section between the respective said bridge passage and a shuttle check valve, and a through shuttle passage between said shuttle check valve of its control section and the shuttle check valve of the next control section, such that if the workport pressure in said bridge passage is greater than the workport pressure in the bridge passage in the previous section, then said shuttle check valve in the present section closes the through shuttle passage of the previous section and opens the sensing shuttle passage of the present section to the through shuttle passage of the present section such that the work port pressure in the bridge passage of the present section is passed through the sensing shuttle passage of the present section to the next section, and such that if the workport pressure in the bridge passage of the present section is less than the workport pressure in the bridge passage of the previous section, then the shuttle check valve of the present section closes the sensing shuttle passage of the present section such that the workport pressure of the previous section flows through the shuttle passage of the previous section and into the through shuttle passage of the present section and into the next section, such that the highest workport pressure is communicated to said pump and to the other side of each of said pressure compensating check valves in said section.
2. The invention according to claim 1, wherein said valve spool is axially reciprocal in said housing, and wherein said through shuttle passage includes a first portion extending axially in said housing from said housing from said shuttle check valve and a second portion extending diagonally transversely across said housing to said shuttle check valves of the next section, said shuttle valve of the present and next sections being substantially aligned along a lateral direction substantially orthogonal to said axis of axial reciprocation of said valve spool, said first portions of said through shuttle passages of the present and next sections also being substantially aligned along said lateral direction.
3. The invention according to claim 2, wherein said second portion of said through shuttle passage has first and second ends, the first end of said second portion of said through shuttle passage of the present section being axially offset from the second end of said second portion of said through shuttle passage of the next section and laterally aligned with an end of said sensing shuttle passage of the next section at said shuttle check valve of said next section, the second end of said second portion of said through shuttle passage of the present section being axially offset from an end of said sending shuttle passage of the present section, and being axially offset from the first end of said second portion of said through shuttle passage of the preceding section, said end of said sensing shuttle passage of the present section being laterally aligned with said first end of said second portion of said through shuttle passage of the preceding section at said shuttle check valve of the present section.
4. The Invention according to claim 3, wherein said sensing shuttle passage of each said section extends diagonally transversely in said housing parallel to said second portion of said through shuttle passage in its respective said section.
5. A hydraulic control valve for use with a variable displacement pump having output and pressure sensing ports, comprising a housing having therein a valve spool movable in a bore to an operating position at which it directs pump output fluid from a pressure fluid supply passage in the bore to a workport characterized by: A means in the housing providing a feeder passage having an inlet branch which has its origin in the bore to receive supply pressure fluid from the supply passage whenever the valve spool is in said operating position thereof, said feeder passage having an outlet branch adjacent to the workport to be communicated therewith through the bore by the valve spool in its said operating position; B. means in the housing defining a check valve chamber, one end portion of which is situated between said branches of the feeder passage and to which the inlet branch thereof opens to receive supply pressure fluid therefrom; C. means in the housing providing a connecting passage to communicate said one end portion of the check valve chamber with the outlet branch of the feeder passage and by which said feeder passage branches are communicable with one another;
D. a load holding check valve in said chamber biased in a closing direction toward a position in said one end portion of its chamber at which it blocks fluid flow to said outlet branch of the feeder passage, said check valve being movable in the opening direction under force exerted thereon by pressure of supply fluid in the inlet branch of the feeder passage to provide for flow of such supply fluid to the outlet branch of the feeder passage; E.
means in the housing for translating workport pressure into force on said check valve in opposition to said valve opening force and capable of moving it in said closing direction whereby said check valve can act to hold a load in the event of pressure drop in the inlet branch of the feeder passage; and F. means in the housing to communicate workport pressure with said sensing port of a variable displacement pump having its output port connected with said supply passage, whereby said check valve can act as a pressure compensating valve to move back and forth and thus vary the degree of communication between the feeder passage branches in response to variations in the opposing fluid pressure forces acting thereon, to thereby maintain a predeterminable difference in pressure between fluid in the supply passage and that in the inlet branch of the feeder passage.
D. a load holding check valve in said chamber biased in a closing direction toward a position in said one end portion of its chamber at which it blocks fluid flow to said outlet branch of the feeder passage, said check valve being movable in the opening direction under force exerted thereon by pressure of supply fluid in the inlet branch of the feeder passage to provide for flow of such supply fluid to the outlet branch of the feeder passage; E.
means in the housing for translating workport pressure into force on said check valve in opposition to said valve opening force and capable of moving it in said closing direction whereby said check valve can act to hold a load in the event of pressure drop in the inlet branch of the feeder passage; and F. means in the housing to communicate workport pressure with said sensing port of a variable displacement pump having its output port connected with said supply passage, whereby said check valve can act as a pressure compensating valve to move back and forth and thus vary the degree of communication between the feeder passage branches in response to variations in the opposing fluid pressure forces acting thereon, to thereby maintain a predeterminable difference in pressure between fluid in the supply passage and that in the inlet branch of the feeder passage.
6. The hydraulic control valve of claim 5, wherein said housing is provided with two workports; the outlet branch of the feeder passage comprises a U-shaped bridge passage which spans that portion of the bore at which the supply passage and the origin of the feeder passage are located, said bridge passage having a pair of legs selectively respectively communicable with said workports by the valve spool; one of said legs being in communication with said connecting passage; and the check valve chamber and check valve therein being substantially embraced by the U-shaped bridge passage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US57939484A | 1984-02-13 | 1984-02-13 | |
| US579,394 | 1984-02-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1246425A true CA1246425A (en) | 1988-12-13 |
Family
ID=24316725
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000473619A Expired CA1246425A (en) | 1984-02-13 | 1985-02-05 | Post-pressure-compensated unitary hydraulic valve |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS60188604A (en) |
| KR (1) | KR930004681B1 (en) |
| AU (1) | AU3849185A (en) |
| BR (1) | BR8500652A (en) |
| CA (1) | CA1246425A (en) |
| DE (1) | DE3504744A1 (en) |
| FR (1) | FR2559595B1 (en) |
| GB (1) | GB2153979B (en) |
| SE (1) | SE463885B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3851193T2 (en) * | 1987-10-02 | 1995-04-06 | Applied Power Inc | Individual flow regulator with pressure compensator. |
| DE4005966C2 (en) * | 1990-02-26 | 1999-08-26 | Mannesmann Rexroth Ag | Valve arrangement for controlling two hydraulic consumers that can be operated simultaneously |
| WO1993013271A1 (en) * | 1991-12-24 | 1993-07-08 | Hitachi Construction Machinery Co., Ltd. | Hydraulic driving apparatus for construction machines |
| GB2271625B (en) * | 1992-10-19 | 1996-07-03 | Dana Corp | A fluid control valve having a pressure compensator assembly |
| FR2756349B1 (en) * | 1996-11-26 | 1999-01-22 | Mannesmann Rexroth Sa | HYDRAULIC DISTRIBUTOR WITH NON-RETURN VALVE |
| DE19727881A1 (en) * | 1997-06-30 | 1999-01-07 | Rexroth Mannesmann Gmbh | Hydraulic path valve with pressure compensation according to quantity distribution principle |
| KR100436299B1 (en) * | 2001-04-19 | 2004-06-18 | 디앤에이중공업 주식회사 | speed-up valve |
| JP2006125548A (en) * | 2004-10-29 | 2006-05-18 | Kayaba Ind Co Ltd | Multiple valve device |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3742982A (en) * | 1971-07-26 | 1973-07-03 | Borg Warner | Control valve |
| GB1452609A (en) * | 1973-05-15 | 1976-10-13 | Sperry Rand Ltd | Hydraulic systems |
| US3881512A (en) * | 1973-09-21 | 1975-05-06 | Koehring Co | Hydraulic control valve and pressure compensating mechanism therefor |
| US3910311A (en) * | 1974-08-26 | 1975-10-07 | Koehring Co | Pressure compensated control valve |
| ZA7696B (en) * | 1975-02-06 | 1976-12-29 | Commercial Shearing | Compensated work port fluid valves and work port compensators |
| DE2514624C3 (en) * | 1975-04-03 | 1986-10-23 | Danfoss A/S, Nordborg | Control device for at least one hydraulically operated double-acting consumer |
| US4089346A (en) * | 1976-07-27 | 1978-05-16 | Tadeusz Budzich | Load responsive fluid control valves |
| US4154262A (en) * | 1977-10-17 | 1979-05-15 | Gresen Manufacturing Company | Hydraulic control system |
| US4194532A (en) * | 1978-04-10 | 1980-03-25 | Caterpillar Tractor Co. | Control valve with bypass means |
| US4352375A (en) * | 1980-04-14 | 1982-10-05 | Commercial Shearing, Inc. | Control valves |
| DE3044144A1 (en) * | 1980-11-24 | 1982-09-09 | Linde Ag, 6200 Wiesbaden | HYDROSTATIC DRIVE SYSTEM WITH ONE ADJUSTABLE PUMP AND SEVERAL CONSUMERS |
| JPS5831486A (en) * | 1981-08-18 | 1983-02-24 | 株式会社東芝 | Sheet paper bundle discharger |
| JPS58106272A (en) * | 1981-12-16 | 1983-06-24 | Uchida Yuatsu Kiki Kogyo Kk | Flux control valve |
-
1985
- 1985-02-05 CA CA000473619A patent/CA1246425A/en not_active Expired
- 1985-02-06 AU AU38491/85A patent/AU3849185A/en not_active Abandoned
- 1985-02-07 SE SE8500569A patent/SE463885B/en not_active IP Right Cessation
- 1985-02-08 GB GB08503214A patent/GB2153979B/en not_active Expired
- 1985-02-11 KR KR1019850000854A patent/KR930004681B1/en not_active IP Right Cessation
- 1985-02-12 BR BR8500652A patent/BR8500652A/en not_active IP Right Cessation
- 1985-02-12 FR FR8501958A patent/FR2559595B1/en not_active Expired - Fee Related
- 1985-02-12 DE DE19853504744 patent/DE3504744A1/en active Granted
- 1985-02-13 JP JP60026131A patent/JPS60188604A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| SE8500569D0 (en) | 1985-02-07 |
| FR2559595A1 (en) | 1985-08-16 |
| SE463885B (en) | 1991-02-04 |
| DE3504744A1 (en) | 1985-08-14 |
| FR2559595B1 (en) | 1993-11-19 |
| GB2153979A (en) | 1985-08-29 |
| AU3849185A (en) | 1985-08-22 |
| GB2153979B (en) | 1988-01-20 |
| BR8500652A (en) | 1985-10-01 |
| KR930004681B1 (en) | 1993-06-03 |
| GB8503214D0 (en) | 1985-03-13 |
| JPS60188604A (en) | 1985-09-26 |
| SE8500569L (en) | 1985-08-14 |
| KR850006049A (en) | 1985-09-28 |
| DE3504744C2 (en) | 1993-03-18 |
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