US3777773A - Pressure compensating valve mechanism - Google Patents

Pressure compensating valve mechanism Download PDF

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US3777773A
US3777773A US00228020A US3777773DA US3777773A US 3777773 A US3777773 A US 3777773A US 00228020 A US00228020 A US 00228020A US 3777773D A US3777773D A US 3777773DA US 3777773 A US3777773 A US 3777773A
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plunger
fluid
spring
piston
pressure
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W Tolbert
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Husco International Inc
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Koehring Co
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Assigned to HUSCO INTERNATIONAL, INC., W239 N218 PEWAUKEE ROAD, WAUKESHA, WISCONSIN, A CORP OF DELAWARE reassignment HUSCO INTERNATIONAL, INC., W239 N218 PEWAUKEE ROAD, WAUKESHA, WISCONSIN, A CORP OF DELAWARE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: KOEHRING COMPANY, A CORP OF DE.
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0416Fluid 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
    • F15B13/0417Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25Pressure control functions
    • F15B2211/253Pressure margin control, e.g. pump pressure in relation to load pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/505Pressure control characterised by the type of pressure control means
    • F15B2211/50509Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/2496Self-proportioning or correlating systems
    • Y10T137/2559Self-controlled branched flow systems
    • Y10T137/2574Bypass or relief controlled by main line fluid condition
    • Y10T137/2605Pressure responsive
    • Y10T137/2612Common sensor for both bypass or relief valve and other branch valve
    • Y10T137/2615Bypass or relief valve opens as other branch valve closes
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/2496Self-proportioning or correlating systems
    • Y10T137/2559Self-controlled branched flow systems
    • Y10T137/2574Bypass or relief controlled by main line fluid condition
    • Y10T137/2605Pressure responsive
    • Y10T137/263Plural sensors for single bypass or relief valve
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/8593Systems
    • Y10T137/87169Supply and exhaust
    • Y10T137/87177With bypass
    • Y10T137/87185Controlled by supply or exhaust valve

Definitions

  • ABSTRACT [22] Filed: 22 1972 A mechanism which, in one form, is useful as an unloading valve, and in another form as a pressure com- [21] Appl. No.1 228,02 pensating valve. It comprises a valve plunger having a bypass position allowing all source fluid entering an [52] Cl n 2. 137/117 91/446 91/451 inlet port to flow to an outlet port, and having a feed I I 13'7/596 position compelling flow of, source fluid to a feeder 151 1m. (:1.
  • This invention relates to controls for fluid motors, and has more particular reference to bypass type pressure compensating valve mechanisms such as are used conjunctionally with a closed center control valve to govern the speed of a fluid motor.
  • such pressure compensating valve mechanisms comprise a fluid pressure actuatable valve plunger or spool which cooperates with the valve elementor main spool of the control valve to regulate flow of pump fluid to the inlet of the control valve in accordance with variations in the pressure differential between pump output fluid and that motor port of the control valve through which pump fluid is being supplied to the motor.
  • the compensating plunger must be held in a bypass position at times when the control valve element is in its neutral or hold position. The purpose of this, of course, is to unload the pump just as an open center control valve does when its valve element is in a neutral position.
  • a compensating valve mechanism having a fluid pressure actuatable plunger movable between feed and bypass positions, and in the latter of which positions the plunger can be held by an exceptionally low pump output pressure, while in the feed position of the plunger, a desirably strong spring force is exerted thereon to strongly resist return movement thereof toward its bypass position.
  • Another object of the invention is to adapt the seriesconnected spring concept mentioned in the preceding paragraph to bypass valve mechanisms per se, as distinguished from pressure compensating valve mechanisms.
  • a piston is confined between the primary and secondary springs and is actuatable in a direction to relax the secondary plunger spring in consequence of subjection of the piston to feedback pressure from the governed motor.
  • FIG. 1 is a diagrammatic view illustrating a fluid pressure operated system embodying a pressure compensating valve mechanism of this invention, showing the plunger thereof in its bypass position;
  • FIG. 2 is a view of the pressure compensating valve mechanism of FIG. 1, but showing the plunger thereof in-a feed position;
  • FIG. 3 is a diagrammatic view of a pump unloading valve embodying this invention.
  • FIGS. 4 and 5 are diagrammatic views of a pressure compensating valve mechanism of modified construction.
  • the numeral 5 designates a reversible fluid motor, here shown as a double acting hydraulic cylinder having a piston rod 6 by which the cylinder can be operatively connected to a load (not shown).
  • the cylinder is supplied with pressure fluid from a pump P, at the dictate of a control valve 8.
  • the control valve has been shown by way of example as a single spool valve of a conventional type. lts valve spool 9 is shiftable axially to working positions at opposite sides of a neutral position (shown), to direct output fluid from the pump through a supply passage 10 to one or the other of a pair of motor ports l1, l2 connecting with the opposite sides of the cylinder.
  • the control valve is of the closed center type having feeder passage means comprising an upstream branch 14 that can be considered as the inlet of the valve, and a downstream branch 15 which is communicable with the upstream branch 14 through the bore 16 in which the valve spool operates.
  • the downstream branch 15 of the feeder passage is communicated with the supply passage 10 through a load holding check valve 17.
  • the supply passage is of inverted U-shape to provide branches l8 and 19 which intersect the bore at locations inwardly adjacent to the junctions of the bore with the service passages 11 and 12, respectively.
  • the valve spool is grooved to provide lands which control communication of the motor ports 11, 12 with either the supply passage branches 18, 19 or with exhaust passages 20, 21 which intersect the bore 16 at locations outwardly adjacent to the junctions of the bore with the motor ports 11 and 12, respectively.
  • a central land 22 on the spool is situated to close off communication between the feeder passage branches l5, 16 in the neutral or hold position of the valve spool shown.
  • Throttle notches 23 and 24 in the left and right hand ends respectively, of the land 22 provide for adjusting the rate at which pressure fluid flows from the upstream feeder branch 14 to the downstream feeder branch 15, upon shifting ofthe valve spool in either direction out of neutral to a flow metering position short of a full operating position of the spool.
  • pressure fluid entering the inlet 14 flows through throttle groove 23 and to the rod end of cylinder 5 via the feeder passage branch 15, check valve 17 and branch 18 ofthe supply passage 10 then in communication with service passage 11.
  • pressure fluid entering the inlet 14 flows through throttle notch 24 and to the head end of the cylinder via feeder branch 15, check valve 17 and supply branch 19 then in communication with the service passage 12.
  • the non-selected service passage is communicated with its adjacent exhaust passage branch or 21 to conduct to the reservoir of the system pressure fluid which is expelled from the cylinder 5.
  • the pressure compensating valve mechanism 25 of this invention is connected in the system between the pump P and the control valve 8, and its purpose is to maintain the flow of pressure fluid to the cylinder at a constant rate determined by the metering position or setting of the control spool 9.
  • the pressure compensating valve is provided with a fluid pressure actuatable plunger 26 which is sensitive to the pressure drop across the orifice provided by either throttle notch 23, 24, and which regulates the flow of pump fluid to the inlet 14 in accordance with variations in said pressure drop from that value thereof which exists when fluid flows to the motor at the desired rate.
  • the plunger 26 of the pressure compensating valve mechanism has hollow opposite end portions, and it is slidably received in a bore 27 which is closed at each end.
  • Five different passages open to the bore at axially spaced zones. Reading from left to right, these passages comprise a low pressure or return port 28, a feedback port 29, an outlet port 30, an inlet port 31, and a feeder port 32.
  • the return port 28 can comprise part of the exhaust passage 20; the feeder port 32 is communicated with the upstream feeder branch 14 by means of a duct 33; and the feedback port 29 can be communicated with either motor port 11, 12 through a shuttle valve in a conventional way. In the single spool control valve shown, however, the feedback port 29 is communicated with the branch 18 of the supply passage 10 by means of a duct 34; or it can be connected to feeder branch 15 with the same results.
  • the feedback port 29 is vented to the reservoir of the system when the control valve spool 9 is in its neutral position by means of an axial passage 35 in the valve spool which communicates at one end with the supply passage branch 18 through a radial passage 36 in the spool, and with the exhaust branch 20 at its other end through a radial passage 37 in the spool.
  • the spool 9 of the control valve When the spool 9 of the control valve is moved to a full operating position at either side of neutral, it provides unrestricted communication between the feeder branches 14 and 15, and the pressure of fluid in the supply passage 10 will be at substantially the same valve as that of pressure fluid in whichever motor port 11 or 12 is then in communication with it. As is customary, this pressure is fed back to the compensating valve mechanism and imposed upon the left hand end of the compensating plunger 26 in opposition to the force which pump output fluid in pressure chamber 38 exerts upon the right hand end of the plunger. A spring also customarily urges the plunger toward its feed position.
  • the spring bias for the plunger is provided by a pair of compression springs, namely, a substantially strong primary spring 40 and a weaker secondary or auxiliary spring 41. Both of these springs are located at the left hand end of the plunger, at opposite axial ends of a stepped piston 42.
  • the primary spring is confined in the well 43 provided by the hollow left hand end portion of the plunger, between the bottom of the well and the adjacent inner end portion 44 of the piston, which is smaller in diameter than the well.
  • a washer 45 is preferably interposed between the piston and the primary spring.
  • the piston is axially slidable in a stepped cylinder 46 which is coaxial with the bore 27, and the small diameter inner end portion of which cylinder opens to the bore.
  • One end portion of the secondary spring extends into a well 47 in the larger diameter outer end portion 48 of the piston, and the other end of the spring extends into a well 49 in a cap 50 which closes the large diameter outer end portion of the cylinder.
  • the spring 41 is confined between the bottoms of the wells 47 and 4 9.
  • the large diameter end portion of the cylinder 46 has greater axial length than that of the piston portion therein, so as to provide a stop 51 which cooperates with the inner end 52 of the cap 50 to define the limits 'of axial sliding motion of the piston.
  • the piston is circumferentially reduced between its large and small diameter ends, as at'53.
  • the space thus provided between the large diameter end of the piston and the inner stop 51 is vented through a hole 54 in the wall of the cartridge 55 in which the piston is housed.
  • the inner end of this cartridge also provides a stop to define the neutral or full bypass position of the compensating plunger 26.
  • the piston is formed with a passage 57 which extends axially therethrough, so that the fluid pressures in the spring chambers at the opposite ends of the piston 42 can be equalized.
  • the compensating plunger occupies a bypass position at which all of the pump output fluid entering its inlet port 31 flows to the outlet port 30, in bypass relation to the feeder port 32.
  • This condition is brought about by reason of the fact that the primary and secondary spring chambers 43 and 47 are vented to the exhaust passage in the control valve through a hole 58 in theside wall of the chamber 43, which hole opens to the feedback port 29 and is always in communication therewith.
  • the feedback port 29 is communicated with the exhaust passage 20 via the duct 34, branch 18 of the supply passage, and the passages 35, 36 and 37 in the control spool 9 in the neutral position of the latter.
  • the total force RT canbe found using the formula Merely by way of example, if R1 equals psi and R2 equals 50 psi, the total force RT which can be exerted on the plunger is 5000 psi divided by psi, or only slightly over 33 psi. Thus it will be seen that the pressure drop across the inlet and outlet ports 31 and 30 will be held to a very desirable low value whenever the control valve spool is in its neutral position and the compensating plunger 26 is in a corresponding neutral or bypass position such as seen in FIG. 1.
  • Feedback fluid then flows into chamber 47 and moves the piston to the right to its limit of motion seen in FIG. 2, so as to then relax the secondary spring 41.
  • the secondary spring 41 becomes ineffective, and the full force of the primary spring is then exerted on the compensating plunger, without opposition from the secondary spring.
  • the position of the compensating plunger, in all operating positions of the control valve spool, will then depend upon pump output pressure as imposed upon the right hand end of the plunger, and upon the combined forces of feedback fluid and of the primary spring 40 acting upon the left hand end of the plunger.
  • the position of the compensating plunger will be automatically adjusted to effe'ctregulation of fluid pressure at the feeder port 32 in accordance with variations in pump output pressure at port 31 and/or in response to variations in feedback pressure; and the plunger will be moved in response to such variations in pressure in the direction to compensate for the changed condition and thereby maintain the pressure at port 32 at a constant value. That is to say, for example, that the plunger will be caused to move to the right to increase fluid pressure at the feeder port 32 in consequence of a rise in pressure at the feedback port 29; and itwill be caused to move to the left to decrease the feeder port pressure as a consequence of a decrease in pressure at the feedback port 29.
  • the compensating plunger functions to maintain constant pressure at the feeder port 32 by varying the degree of communication between the pump port 31 and the outlet port 30.
  • the pressure compensating plunger will function to maintainfeeder port pressure constant by varying the degree of communication between the feeder port and the pump port 31 at times when port 30 is in use as a high pressure carry-over port for a downstream control valve and the spool of the latter is operating a fluid motor at a greater pressure than that being operated by the upstream spool.
  • Actuation of the control spool 9 to a full flow position will effect complete close-off of the outlet port 30 from the inlet port 31, so that all pump fluid will then be compelled to flow to the work cylinder.
  • the spring force tending to move the compensating plunger out of its bypass position is desirably low, while a much greater spring force resists movement of the plunger out of its feed position at times when pressure fluid is being directed to one end or the other of the cylinder 5. This last assures the desired precise control over the speed at which the cylinder operates.
  • PK] 3 illustrates how the series spring concept described above can be used to advantage in a pump unloading valve.
  • the unloading valve is similar in most respects to the pressure compensating valve described earlier, although it can be made somewhat simpler.
  • its plunger 65 comprises a cup shaped member comparable to the large diameter end portion of the compensating plunger 26 at the left hand end thereof, and having its closed end 66 movable into and out of engagement with a seat 67 provided by a short portion of the bore 68 in which the valve plunger is axially slidably received.
  • the unloading valve is also provided with a reservoir port 69, a feedback port 70, an outlet port 71, an inlet port 72, and a feeder port 73. While the inlet and outlet ports open to the bore 68 at axially opposite sides of the bore portion 67, the feeder port 73 can be directly communicated with the inlet port 72, to form a part thereof, as shown.
  • the reservoir port 69 opens to a counterbore 74 in which is secured the cartridge 75 containing the stepped piston 76.
  • the piston of course, is slidable axially in a stepped cylinder provided in the interior of the cartridge, as before; and the primary and secondary plunger springs 77 and 78, respectively, are again located at axially opposite ends of the piston, with the primary spring extending into the hollow interior 79 of the valve plunger 65.
  • the plunger 65 is shown as extending outwardly of the bore 68 into the counterbore 74, to engage the inner end of the cartridge 75, which thus defines the fully open or bypass position of the plunger.
  • a snap ring 80 confined in a groove in the exterior of the plunger is engageable with the bottom 81 of the counterbore to define the closed position of the plunger at which its right hand end is received within the seat defining bore portion 67 to block communication between the inlet port 72 and the outlet port 71.
  • a hole 83 in the side wall of the plunger 65 communicates with the feedback port 70 and provides for entry of feedback fluid into the interior of the plunger to effect pressurization of the chambers at the opposite ends of the piston 76.
  • the pump unloading valve operates in substantially the same way as the pressure compensating valve.
  • the feedback port is vented and the feeder passage is closed off.
  • pump output fluid entering the inlet port 72 acts upon the closed end 66 of the plunger and moves the same to its fully open position shown, against the substantially light resistance of the serially connected primary and secondary springs 77 and 78. All of the pump fluid entering port 72 then flows through outlet port 71 and back to the reservoir, with but slight pressure drop between ports 71 and 72.
  • valve plunger 65 it is also possible for the valve plunger 65 to occupy a partially closed position allowing some of the pump output fluid to flow to the outlet port and constraining the remainder to flow to the feeder port. Such a situation can arise from placement of the control valve spool in a metering position on the order of that described earlier, so that the plunger 65 would then respond to variations in the pressure drop across the orifice provided by the throttle groove through which the work cylinder was supplied with pump output fluid.
  • the feedback port 70 of the unloading valve could be communicated with the motor ports of the associated control valve through a shuttle valve arrangement in a more or less conventional way.
  • FIG. 4 illustrates another version of the pressure compensating valve mechanism of this invention. lts plunger 89, shown in bypass position, is again provided with a circumferential groove 90, and it is reciprocable endwise in a bore 91 whose opposite ends are closed.
  • the plunger groove communicates a pump inlet port 93 with an outlet port 94 to cause pump output fluid to bypass a feeder port 95.
  • the plunger occupies this unloading or bypass position when the spool of the associated control valve is in its neutral position closing off flow therethrough of pump output fluid from the feeder port and venting the left hand end of the bore 91 through a feedback port 96 therein.
  • the plunger 89 In the feed position of the plunger 89, its left hand land can limit or even close off flow of pump output fluid to the outlet port from the inlet port to thereby divert a regulatable volume of pump output fluid to the feeder port 95 through the groove 90.
  • the plunger moves to its feed position in consequence of actuation of the spool of the associated control valve to an operating position allowing for flow of pumpoutput fluid therethrough from the feeder port and pressurizing the feedback port 96 in the manner described earlier.
  • Coaxial wells 97 and 98 provide spring chambers in the opposite ends of the plunger.
  • a secondary spring 5 100 situated in the well 98 acts upon a piston 101 in said well to urge the piston toward one limit of motion at which its outer end abuts the adjacent end of the bore 91. In that limit of motion, the piston may hold the secondary spring lightly loaded.
  • the piston 101 can be moved inwardly into the well 98 by the pressure of fluid in the chamber 102 provided by the right hand end portion of the bore to further compress the secondary spring. It is for this reason that the well 98 is at all times vented to a reservoir port 103, through a passageway 104 in the compensating plunger.
  • the secondary spring 100 tends to move the compensating plunger 89 to the left, toward its bypass or pump unloading position. It acts upon the plunger in opposition to a primary spring 105 which is situated in the well 97 in the outer end of the compensating plunger 89 and tends to move the same toward its feed position. While the secondary spring thus opposes the primary spring, the latter is slightly stronger and tends to normally move the plunger toward the right hand end of 25 the bore 91, to its feed position.
  • the pressure chamber 102 in the right hand end of the bore 91 is at all times communicated with the feeder port 95, and hence with the inlet port 93, via a passageway 106 in the compensating plunger.
  • the piston 101 is provided with a stem 107 which projects coaxially into the secondary spring and toward the bottom of the well 98, with which it can engage to define the inner limit of motion of the piston relative to the compensating plunger.
  • the compensating plunger will be normally held in its bypass or pump unloading position as long as the spool of the associated control valve remains in its neutral position venting the feedback port 96 and blocking flow of pump output fluid through the feeder port 95.
  • pump output fluid flows directly to the outlet port 94 in bypass relationto the feeder port, and its pressure is manifested in the chamber 102 at the right hand end of the compensating plunger.
  • the substantially small force which'pump output fluid is able to exert upon the right hand end of the plunger, when added to the greater force of the secondary spring 100, produces a total force in excess of that exerted upon the plunger by the primary spring 105.
  • the plunger is held in its bypass position mainly by reason of the force of the secondary spring, which greatly counteracts the force of the primary spring.
  • the primary spring acts upon the plunger without opposition from the secondary spring and provides the desirably strong bias essential to precise control over the rate at which pump output fluid flows to the feeder port 95.
  • the compensating plunger will respond to variations in the pressure differential between fluid at the inlet port 93 and feedback fluid at the feedback port 96, and effect regulation of fluid flow to thefeeder port in accordance with such variations.
  • this invention makes possible the provision of a pressure compensating valve having a plunger which can be maintained in a bypass position under relatively light force, and in which a substantially strong spring force is made available to resist movement of the plunger out of its feed position.
  • a fluid flow controlling valve mechanism having a body with an inlet and an outlet and feeder and feedback ports all opening to a bore containing a fluid pressure responsive valve plunger, means to impose the pressure of fluid at the inlet upon a first surface of the plunger to urge it in one axial direction toward a normal position at which pressure fluid entering the bore from the inlet flows to the outlet in bypass relation to the feeder port, and means by which the pressure of fluid at the feedback port can be imposed upon a second surface of the plunger to move it in the opposite axial direction toward a feed position compelling inlet fluid to flow to the feeder port, characterized by:
  • the fluid flow controlling valve mechanism of claim 1 further characterized by:
  • said means which is connected with the secondary spring comprising a piston which is movable in one direction from one position to another position at which the secondary spring is ineffective to oppose the primary spring;
  • said means which is connected with the secondary spring comprising a piston confined between said springs and movable axially toward said second surface on the plunger to relax the secondary spring;
  • the fluid flow controlling valve mechanism of claim 5 further characterized by:
  • the plunger having a well in its end adjacent to said piston, in which the primary spring is received;
  • a pressure compensating valve mechanism having inlet, outlet, feeder and feedback ports all opening to a bore containing a fluid pressure responsive valve plunger, said mechanism being of the type having provision for delivery of inlet fluid to one end of the bore where it can exert force on the plunger and normally hold it in a neutral position at which inlet fluid can flow to the outlet in bypass relation to the feeder port, and wherein the plunger is movable to an operating position limiting said bypass flow and diverting inlet fluid to the feeder port, characterized by:
  • A. means opening to the other end of the bore providing a cylinder coaxial with the bore;
  • a pressure compensating valve mechanism having a plunger movable axially in a bore in the body of the mechanism and having means to impose the pres-l sure of fluid at an inlet upon a first surface of the plunger to urge it axially in one direction in the bore toward a normal position at which fluid entering the bore from the inlet flows to an outlet in bypass relation to a feeder port, and having a feedback port by which the pressure of feedback fluid can be imposed upon asecond surface of the plunger to move it in the opposite axial direction toward a feed position compelling inlet fluid to flow to the feeder port, characterized by:
  • C. means defining a cylinder
  • a piston in the cylinder connected with the secondary spring and operable in said normal position of the plunger to render the secondary spring effective to impose force upon the plunger in opposition to the force of the primary spring providing the piston is in one axial position at which it engages an abutment on the body, said piston being movable away from said abutment to a second position at which it renders the secondary spring ineffective;
  • the pressure compensating valve mechanism of claim 11 further characterized by:
  • a pressure compensating valve mechanism having a plunger operable in a feed position to regulate the rate at which pump fluid flows from an inlet to a feeder port in accordance with variations in the pressure differential between the feeder port and a feedback port, and wherein the plunger is held in a normal position displaced from its feed position under force which inlet fluid exerts upon one surface thereof to allow inlet fluid to flow to an outlet in bypass relation to the feeder port, characterized by:
  • A a strong primary plunger spring

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Reciprocating Pumps (AREA)
  • Flow Control (AREA)
  • Control Of Fluid Pressure (AREA)
US00228020A 1972-02-22 1972-02-22 Pressure compensating valve mechanism Expired - Lifetime US3777773A (en)

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US22802072A 1972-02-22 1972-02-22

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US (1) US3777773A (ko)
JP (1) JPS4897120A (ko)
CA (1) CA944255A (ko)
DE (1) DE2302845A1 (ko)
FR (1) FR2173516A5 (ko)
GB (1) GB1416263A (ko)

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US3971216A (en) * 1974-06-19 1976-07-27 The Scott & Fetzer Company Load responsive system with synthetic signal
US3976090A (en) * 1975-02-25 1976-08-24 Johnson Philip C Slow start hydraulic valve
US4003400A (en) * 1975-04-07 1977-01-18 The Boeing Company Self-depressurizing metering valve
US4121610A (en) * 1976-02-02 1978-10-24 Ambac Industries Incorporated Electrically operated proportional flow control hydraulic valve and manually operable remote control device therefor
US4199005A (en) * 1976-08-20 1980-04-22 Tadeusz Budzich Load responsive control valve
US4209039A (en) * 1978-04-10 1980-06-24 Tadeusz Budzich Load responsive control valve
US4216797A (en) * 1978-04-10 1980-08-12 Tadeusz Budzich Load responsive control valve
US4253482A (en) * 1979-03-05 1981-03-03 Gresen Manufacturing Company Hydraulic valve having pressure compensated demand flow
US4303091A (en) * 1979-03-01 1981-12-01 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4352375A (en) * 1980-04-14 1982-10-05 Commercial Shearing, Inc. Control valves
US4361169A (en) * 1979-11-13 1982-11-30 Commercial Shearing, Inc. Pressure compensated control valves
US4649951A (en) * 1984-07-03 1987-03-17 Maurice Tardy Assisted slide for pressure compensation in a hydraulic distributor
US4693272A (en) * 1984-02-13 1987-09-15 Husco International, Inc. Post pressure compensated unitary hydraulic valve
US4984603A (en) * 1988-02-29 1991-01-15 Kabushiki Kaisha Komatsu Seisakusho Flow control valve assembly
US5152140A (en) * 1989-10-11 1992-10-06 Hitachi Construction Machinery Co., Ltd. Pressure compensating valve spool positioned by difference in pressure receiving areas for load and inlet pressures
US5447093A (en) * 1993-03-30 1995-09-05 Caterpillar Inc. Flow force compensation
US5501136A (en) * 1993-06-24 1996-03-26 Voac Hydraulics Boras Ab Control system for a hydraulic motor
US5791142A (en) * 1997-03-27 1998-08-11 Husco International, Inc. Hydraulic control valve system with split pressure compensator
US5794441A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid feedback control
US5794437A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Regenerative adaptive fluid motor control
US5794442A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid motor control
US5794440A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid control
US5794438A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid motor feedback control
US5794439A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Regenerative adaptive fluid control
WO1999064760A1 (en) * 1998-06-12 1999-12-16 Lisniansky, Robert, M. Regenerative adaptive fluid motor control
WO1999064761A1 (en) * 1998-06-12 1999-12-16 Lisniansky Robert M Regenerative adaptive fluid control
US6164310A (en) * 1998-06-22 2000-12-26 Shimadzu Corporation Priority type flow dividing valve
US20050081518A1 (en) * 2003-10-20 2005-04-21 Pengfei Ma Flow-control apparatus for controlling the swing speed of a boom assembly
US20090320937A1 (en) * 2008-05-22 2009-12-31 Honeywell International, Inc. Pressurizing and pressure regulating valve and fuel supply system employing the same
WO2012128797A2 (en) 2011-03-22 2012-09-27 Parker Hannifin Corporation Electro-proportional pilot operated poppet valve with pressure compensation
WO2014022275A1 (en) * 2012-08-01 2014-02-06 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US9149576B2 (en) 2012-10-11 2015-10-06 Magnolia Medical Technologies, Inc. Systems and methods for delivering a fluid to a patient with reduced contamination
US20150338857A1 (en) * 2014-05-20 2015-11-26 Hamilton Sundstrand Corporation Pressure-regulating valves
CN106015144A (zh) * 2016-07-18 2016-10-12 江苏恒立液压科技有限公司 液压卸荷装置
US20170234176A1 (en) * 2016-02-11 2017-08-17 SLPT Global Pump Group Automotive lubricant pumping system with two piece relief valve
US9788775B2 (en) 2013-03-12 2017-10-17 Magnolia Medical Technologies, Inc. Methods and apparatus for selectively occluding the lumen of a needle
US9855002B2 (en) 2006-12-18 2018-01-02 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US9950084B2 (en) 2015-09-03 2018-04-24 Magnolia Medical Technologies, Inc. Apparatus and methods for maintaining sterility of a specimen container
US9999383B2 (en) 2012-11-30 2018-06-19 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
US10039483B2 (en) 2011-10-13 2018-08-07 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10123783B2 (en) 2014-03-03 2018-11-13 Magnolia Medical Technologies, Inc. Apparatus and methods for disinfection of a specimen container
US10251590B2 (en) 2012-12-04 2019-04-09 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US10292633B2 (en) 2012-05-30 2019-05-21 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10323762B2 (en) * 2016-04-21 2019-06-18 Parker-Hannifin Corporation Three-way pressure control and flow regulator valve
US10433779B2 (en) 2012-05-30 2019-10-08 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10772548B2 (en) 2012-12-04 2020-09-15 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US11076787B2 (en) 2017-09-12 2021-08-03 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11234626B2 (en) 2015-06-12 2022-02-01 Magnolia Medical Technologies, Inc. Devices and methods for syringe-based fluid transfer for bodily-fluid sampling
US11419531B2 (en) 2017-12-07 2022-08-23 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
EP4170188A1 (en) * 2021-10-21 2023-04-26 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor
US11786155B2 (en) 2019-02-08 2023-10-17 Magnolia Medical Technologies, Inc. Devices and methods for bodily fluid collection and distribution
US11857321B2 (en) 2019-03-11 2024-01-02 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same

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US3143127A (en) * 1962-11-07 1964-08-04 Clark Equipment Co Regulating valve
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Cited By (103)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878864A (en) * 1973-12-07 1975-04-22 Borg Warner Bypass valve
US3971216A (en) * 1974-06-19 1976-07-27 The Scott & Fetzer Company Load responsive system with synthetic signal
US3976090A (en) * 1975-02-25 1976-08-24 Johnson Philip C Slow start hydraulic valve
US4003400A (en) * 1975-04-07 1977-01-18 The Boeing Company Self-depressurizing metering valve
US4127144A (en) * 1975-04-07 1978-11-28 The Boeing Company Self-depressurizing metering valve
US4121610A (en) * 1976-02-02 1978-10-24 Ambac Industries Incorporated Electrically operated proportional flow control hydraulic valve and manually operable remote control device therefor
US4199005A (en) * 1976-08-20 1980-04-22 Tadeusz Budzich Load responsive control valve
US4209039A (en) * 1978-04-10 1980-06-24 Tadeusz Budzich Load responsive control valve
US4216797A (en) * 1978-04-10 1980-08-12 Tadeusz Budzich Load responsive control valve
US4355655A (en) * 1979-03-01 1982-10-26 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4303091A (en) * 1979-03-01 1981-12-01 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4253482A (en) * 1979-03-05 1981-03-03 Gresen Manufacturing Company Hydraulic valve having pressure compensated demand flow
US4361169A (en) * 1979-11-13 1982-11-30 Commercial Shearing, Inc. Pressure compensated control valves
US4352375A (en) * 1980-04-14 1982-10-05 Commercial Shearing, Inc. Control valves
US5794441A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid feedback control
US5794439A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Regenerative adaptive fluid control
US5794438A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid motor feedback control
US5794440A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid control
US5794442A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Adaptive fluid motor control
US5794437A (en) * 1981-11-05 1998-08-18 Lisniansky; Robert Moshe Regenerative adaptive fluid motor control
US4693272A (en) * 1984-02-13 1987-09-15 Husco International, Inc. Post pressure compensated unitary hydraulic valve
US4649951A (en) * 1984-07-03 1987-03-17 Maurice Tardy Assisted slide for pressure compensation in a hydraulic distributor
US4984603A (en) * 1988-02-29 1991-01-15 Kabushiki Kaisha Komatsu Seisakusho Flow control valve assembly
US5152140A (en) * 1989-10-11 1992-10-06 Hitachi Construction Machinery Co., Ltd. Pressure compensating valve spool positioned by difference in pressure receiving areas for load and inlet pressures
US5447093A (en) * 1993-03-30 1995-09-05 Caterpillar Inc. Flow force compensation
US5501136A (en) * 1993-06-24 1996-03-26 Voac Hydraulics Boras Ab Control system for a hydraulic motor
US5791142A (en) * 1997-03-27 1998-08-11 Husco International, Inc. Hydraulic control valve system with split pressure compensator
WO1999064761A1 (en) * 1998-06-12 1999-12-16 Lisniansky Robert M Regenerative adaptive fluid control
WO1999064760A1 (en) * 1998-06-12 1999-12-16 Lisniansky, Robert, M. Regenerative adaptive fluid motor control
US6164310A (en) * 1998-06-22 2000-12-26 Shimadzu Corporation Priority type flow dividing valve
US20050081518A1 (en) * 2003-10-20 2005-04-21 Pengfei Ma Flow-control apparatus for controlling the swing speed of a boom assembly
GB2407400A (en) * 2003-10-20 2005-04-27 Caterpillar Inc Flow control apparatus for swing speed of a boom assembly
GB2407400B (en) * 2003-10-20 2007-06-27 Caterpillar Inc A flow-control apparatus for controlling the swing speed of a boom assembly
US10028687B2 (en) 2006-12-18 2018-07-24 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US10045724B2 (en) 2006-12-18 2018-08-14 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US9855002B2 (en) 2006-12-18 2018-01-02 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US10028689B2 (en) 2006-12-18 2018-07-24 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US10028688B2 (en) 2006-12-18 2018-07-24 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US10052053B2 (en) 2006-12-18 2018-08-21 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US10299713B2 (en) 2006-12-18 2019-05-28 Magnolia Medical Technolgies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US9872645B2 (en) 2006-12-18 2018-01-23 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US9861306B2 (en) 2006-12-18 2018-01-09 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US9855001B2 (en) 2006-12-18 2018-01-02 Magnolia Medical Technologies, Inc. Systems and methods for parenterally procuring bodily-fluid samples with reduced contamination
US8256445B2 (en) * 2008-05-22 2012-09-04 Honeywell International Inc. Pressurizing and pressure regulating valve and fuel supply system employing the same
US20090320937A1 (en) * 2008-05-22 2009-12-31 Honeywell International, Inc. Pressurizing and pressure regulating valve and fuel supply system employing the same
WO2012128797A2 (en) 2011-03-22 2012-09-27 Parker Hannifin Corporation Electro-proportional pilot operated poppet valve with pressure compensation
CN103857925A (zh) * 2011-03-22 2014-06-11 派克汉尼芬公司 具有压力补偿的电比例先导型提升阀
WO2012128797A3 (en) * 2011-03-22 2013-03-14 Parker Hannifin Corporation Electro-proportional pilot operated poppet valve with pressure compensation
US10265007B2 (en) 2011-10-13 2019-04-23 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10039483B2 (en) 2011-10-13 2018-08-07 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10433779B2 (en) 2012-05-30 2019-10-08 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10736554B2 (en) 2012-05-30 2020-08-11 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10912506B2 (en) 2012-05-30 2021-02-09 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US11395611B2 (en) 2012-05-30 2022-07-26 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US11395612B2 (en) 2012-05-30 2022-07-26 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10292633B2 (en) 2012-05-30 2019-05-21 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US11819329B2 (en) 2012-05-30 2023-11-21 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US11998332B2 (en) 2012-05-30 2024-06-04 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US10881343B2 (en) 2012-08-01 2021-01-05 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
WO2014022275A1 (en) * 2012-08-01 2014-02-06 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US9204864B2 (en) 2012-08-01 2015-12-08 Magnolia Medical Technologies, Inc. Fluid diversion mechanism for bodily-fluid sampling
US9931466B2 (en) 2012-10-11 2018-04-03 Magnolia Medical Tehnologies, Inc. Systems and methods for delivering a fluid to a patient with reduced contamination
US11890452B2 (en) 2012-10-11 2024-02-06 Magnolia Medical Technologies, Inc. Systems and methods for delivering a fluid to a patient with reduced contamination
US10220139B2 (en) 2012-10-11 2019-03-05 Magnolia Medical Technologies, Inc. Systems and methods for delivering a fluid to a patient with reduced contamination
US9149576B2 (en) 2012-10-11 2015-10-06 Magnolia Medical Technologies, Inc. Systems and methods for delivering a fluid to a patient with reduced contamination
US11660030B2 (en) 2012-11-30 2023-05-30 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
US11311218B2 (en) 2012-11-30 2022-04-26 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
US11589786B2 (en) 2012-11-30 2023-02-28 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
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US11607159B2 (en) 2012-11-30 2023-03-21 Magnolia Medical Technologies, Inc. Bodily-fluid transfer system for bodily fluid sampling
US9999383B2 (en) 2012-11-30 2018-06-19 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
US11317838B2 (en) 2012-11-30 2022-05-03 Magnolia Medical Technologies, Inc. Syringe-based fluid diversion mechanism for bodily fluid sampling
US10251590B2 (en) 2012-12-04 2019-04-09 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US11737693B2 (en) 2012-12-04 2023-08-29 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US10772548B2 (en) 2012-12-04 2020-09-15 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US11259727B2 (en) 2012-12-04 2022-03-01 Magnolia Medical Technologies, Inc. Sterile bodily-fluid collection device and methods
US10478109B2 (en) 2013-03-12 2019-11-19 Magnolia Medical Technologies, Inc. Methods and apparatus for selectively occluding the lumen of a needle
US9788775B2 (en) 2013-03-12 2017-10-17 Magnolia Medical Technologies, Inc. Methods and apparatus for selectively occluding the lumen of a needle
US11439332B2 (en) 2013-03-12 2022-09-13 Magnolia Medical Technologies, Inc. Methods and apparatus for selectively occluding the lumen of a needle
US9788774B2 (en) 2013-03-12 2017-10-17 Magnolia Medical Technologies, Inc. Methods and apparatus for selectively occluding the lumen of a needle
US11589843B2 (en) 2014-03-03 2023-02-28 Magnolia Medical Technologies, Inc. Apparatus and methods for disinfection of a specimen container
US10123783B2 (en) 2014-03-03 2018-11-13 Magnolia Medical Technologies, Inc. Apparatus and methods for disinfection of a specimen container
US10866600B2 (en) 2014-05-20 2020-12-15 Hamilton Sundstrand Corporation Pressure-regulating valves
US20150338857A1 (en) * 2014-05-20 2015-11-26 Hamilton Sundstrand Corporation Pressure-regulating valves
US10007276B2 (en) * 2014-05-20 2018-06-26 Hamilton Sundstrand Corporation Pressure-regulating valves
US11234626B2 (en) 2015-06-12 2022-02-01 Magnolia Medical Technologies, Inc. Devices and methods for syringe-based fluid transfer for bodily-fluid sampling
US9950084B2 (en) 2015-09-03 2018-04-24 Magnolia Medical Technologies, Inc. Apparatus and methods for maintaining sterility of a specimen container
US10624977B2 (en) 2015-09-03 2020-04-21 Magnolia Medical Technologies, Inc. Apparatus and methods for maintaining sterility of a specimen container
US20170234176A1 (en) * 2016-02-11 2017-08-17 SLPT Global Pump Group Automotive lubricant pumping system with two piece relief valve
US10392977B2 (en) * 2016-02-11 2019-08-27 Slw Automotive Inc. Automotive lubricant pumping system with two piece relief valve
US10323762B2 (en) * 2016-04-21 2019-06-18 Parker-Hannifin Corporation Three-way pressure control and flow regulator valve
CN106015144A (zh) * 2016-07-18 2016-10-12 江苏恒立液压科技有限公司 液压卸荷装置
US11653863B2 (en) 2017-09-12 2023-05-23 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11529081B2 (en) 2017-09-12 2022-12-20 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11076787B2 (en) 2017-09-12 2021-08-03 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11903709B2 (en) 2017-09-12 2024-02-20 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11903710B2 (en) 2017-09-12 2024-02-20 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11419531B2 (en) 2017-12-07 2022-08-23 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11786155B2 (en) 2019-02-08 2023-10-17 Magnolia Medical Technologies, Inc. Devices and methods for bodily fluid collection and distribution
US11857321B2 (en) 2019-03-11 2024-01-02 Magnolia Medical Technologies, Inc. Fluid control devices and methods of using the same
US11852249B2 (en) 2021-10-21 2023-12-26 Bucher Hydraulics S.P.A Inlet section for use in a hydraulic distributor
EP4279750A1 (en) * 2021-10-21 2023-11-22 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor
EP4170188A1 (en) * 2021-10-21 2023-04-26 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor

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FR2173516A5 (ko) 1973-10-05
CA944255A (en) 1974-03-26
DE2302845A1 (de) 1973-08-30
GB1416263A (en) 1975-12-03
JPS4897120A (ko) 1973-12-11

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