WO1980000870A1 - Tiroir de vanne a faible reaction a rainures de fuites et procede de fabrication - Google Patents

Tiroir de vanne a faible reaction a rainures de fuites et procede de fabrication Download PDF

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Publication number
WO1980000870A1
WO1980000870A1 PCT/US1978/000116 US7800116W WO8000870A1 WO 1980000870 A1 WO1980000870 A1 WO 1980000870A1 US 7800116 W US7800116 W US 7800116W WO 8000870 A1 WO8000870 A1 WO 8000870A1
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WO
WIPO (PCT)
Prior art keywords
spool
land
fluid
valve
end surface
Prior art date
Application number
PCT/US1978/000116
Other languages
English (en)
Inventor
L Hall
Original Assignee
L Hall
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by L Hall filed Critical L Hall
Priority to PCT/US1978/000116 priority Critical patent/WO1980000870A1/fr
Publication of WO1980000870A1 publication Critical patent/WO1980000870A1/fr

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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
    • F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
    • F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
    • F16K11/065—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members
    • F16K11/07—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with cylindrical slides
    • F16K11/0708—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with cylindrical slides comprising means to avoid jamming of the slide or means to modify the flow

Definitions

  • a spool valve includes a valve body containing at least two valve chambers both of which are intersected by a bore in which a valve spool is disposed for axial movement. Spaced-apart land portions of the spool define opposite walls of an annular spool groove which enables the two valve chambers to be selectively communicated by shifting the spool so that flow may pass from one chamber to the other through the groove.
  • opening and closing of a valve of this kind tends to be extremely abrupt as a very small amount of spool movement at the critical point produces a relatively large change in the effective flow aperture between the two valve chambers.
  • Reaction forces tend to change both with changes in the. position of the spool and with changes in the pressure drop through the metering slot such as may be caused, for example, by changes in the load reacting on a fluid motor which is controlled by the valve. If the spool has a plurality of grooves for simultaneously effecting a plurality of valving functions, the net reaction force on the, spool tends to be still more non-uniform at different stages of spool travel and may be asymmetrical for different directions of travel.
  • pilot fluid pressures intended to establish specific spool positions
  • flow patterns and flow velocities vary at the different localized regions of these passages in a highly complex manner which is difficult to analyze mathematically.
  • certain changes in the groove-and-slot configuration are not found to have the effects which might be expected. For example, altering the curvature of the fluid entrance end of the metering slot in an attempt to control reaction force does not tend to be effective.
  • metering slots may be divided into two broad categories on the basis of the direction of the fluid flow relative to the centerline of the valve spool at the point where the metering action occurs.
  • a first category using what is termed "meter-in" slots, the metering or throttling action at which the major pressure drop occurs is situated at the fluid entrance end of the slot where the fluid is moving into the groove and radially inward with respect to the spool axis.
  • the other category of metering slots is identified by the term "meter-out" and employs slots arranged so that the metering or throttling action is at the fluid exit end of the metering slots where the fluid flow is directed out of the groove and radially outward with respect to the spool axis. While other design considerations may sometimes rule out the practice, it has been recognized that the meter-in configuration produces relatively lower and more easily controlled spool reaction forces. In addition to providing for a meter-in arrangement where possible, various specialized groove-and-slot configurations have been used to further reduce and control flow reaction forces.
  • the machinist or an automatic control may readily position the cutter to establish one end of the slot at a precise location, but the location and angle of inclination of the other end of the slot then becomes dependent on the diameter of the rotary cutting tool and the tool diameter tends to change quickly in use due to wear and resharpenings.
  • a valve spool configuration for reducing net flow reaction forces in a metering valve in which the spool is movable in one direction within a valve body bore to block communication between two valve chambers and is movable in an opposite direction to establish a selected degree of communication between the two chambers.
  • the spool has first and second annular land portions with facing end surfaces that define opposite walls of an annular spool groove, the spool being movable from a closed position at which the first land portion blocks communication between the two valve chambers to an open position at which the valve chambers are communicated through the groove.
  • the end surface of the second land has a predetermined inclination selected to cause fluid to flow out of the groove at an angle which reduces reaction forces on the spool.
  • the spool is further provided with at least one axially directed metering slot having a fluid entrance end extending into the first land through the end surface thereof.
  • the metering slot has a central portion cut into the base of the groove and has a fluid discharge end that curves radially outwardly into a discharge flow path extending along at least a portion of the end surface of the second land portion at a predetermined inclination which reduces the net reaction forces exerted on the spool by the flow.
  • an economical method of manufacturing a valve spool of the above-described kind to precise tolerances comprises machining an annular coaxial groove on a work piece of circular cross section to form first and second spool land portions having facing end surfaces which define the walls of the groove, the end surface of the second land surface being formed to constitute a conical ramp surface of predetermined inclination. Further steps include cutting. at least one axially directed metering slot into the side of the work piece with a cutting tool, including cutting one end of the slot into the first land portion and the end surface thereof and cutting a central portion of the slot into the base of the groove.
  • the cutting tool is then traveled towards the end surface of the second land portion and to form an end portion of the slot which curves into a fluid discharge path extending along the conical ramp surface at the predetermined inclination.
  • the invention enables the angle of discharge of fluid from the metering slot and groove to be fixed at a preferred inclination relative to the spool axis. In a preferred form of the invention this discharge angle is fixed at about 69° to conform with the effective entrance angle at which the fluid is metered Into the other end of the slot.
  • the controlled reaction forces generated at the discharge end of the slot then serve to counteract at least partially the less controllable forces at the entrance end enabling a very desirable reduction of the net reaction forces on the spool. Consequently less force is required to shift the spool and the maintaining of the spool at a selected position becomes easier as axial reaction force variations experienced by the spool are of lessened magnitude.
  • Figure 1 is an axial section view of a pilot-operated metering valve embodiment of the present invention as employed for the control of a fluid motor, components of the fluid circuit other than the spool valve and pilot means being shown in schematic form,
  • Figure 2 is an enlarged elevation view of a portion of the spool of the valve of Figure 1, with the upper half of the spool being shown in axial section form,
  • Figure 3 is a cross section view of the valve spool taken along line III-III of Figure 2,
  • Figure 4 is a cross section view of another portion of the spool taken along lines IV-IV of Figure 2, and
  • Figure 5 is a diagrammatic depiction of steps which may be employed in the manufacture of the valve spool of the preceding figures. Best Mode for Carrying Out the Invention
  • valve spool 11 embodying the invention is shown as employed in the context of a pilot-operated control valve 12 for a fluid motor 13 which is of the piston-and-cylinder 13a form in this example.
  • the valve spool construction has pronounced advantages in this particular context as will hereinafter be discussed in more detail but is also applicable to diverse other forms of.spool valves for selectively opening and closing one or more fluid flow paths.
  • Control valve 12 has a valve body 14 with a bore 16 in which the spool 11 is disposed for axial movement relative to the valve body.
  • Valve body 14 also has an inlet port 17 which receives pressurized fluid from a pump 18 and which is communicated with an annular inlet chamber 19 and also with an annular flow return chamber or first chamber 21, both such chambers being intersected by bore 16.
  • a relief valve 22 is connected between the outlet of pump 18 and the tank or reservoir 23 from which the pump obtains fluid.
  • Valve body 14 also has first and second service ports 24 and 26 respectively connected with the rod end and the head end of the fluid cylinder 13 and which are also respectively communicated with first and second spaced-apart annular service chambers 27 and 28 which are intersected by bore 16 and which are situated at opposite sides of the inlet chamber 19.
  • the valve body 14 further has a pair of drain ports 29 and 31, each communicated with reservoir 23. Drain port 29 also communicates with three separate annular drain chambers 32, 33 and 34, each of which is coaxial with bore 16 and intersected thereby. Drain chamber 32 and second chamber 33 are situated between service chamber 28 and flow return chamber 21, with chamber 32 being closest to chamber 28 and chamber 33 being closest to chamber 21. Drain chamber 34 is on the opposite side of the flow return chamber 21 from second chamber 33.
  • the second drain port 31 communicates with still another annular drain chamber 36 intersected by bore 16 and which is on the opposite side of service chamber 27 from inlet chamber 19.
  • control valve 12 may be of the manually actuated form in which an operator shifts the position of spool 11 through a control lever and linkage or the like
  • the control valve of this example is of the fluid pressure piloted form which is preferable or sometimes necessary where the magnitude of the fluid pressures in the circuit create high resistance to spool movement or generate strong reaction forces tending to shift the spool.
  • the use of a pilot operated system may also be dictated in some instances because of a remote location of the control valve from the operator's position.
  • one end of the spool 11 Is formed by a land 37 exposed to fluid pressure within a first pilot chamber 38 housing at one end of the valve body 14 and which has a first pilot port 39.
  • An axial extension of the other end of the spool includes a reduced diameter portion 41 extending to a terminal land 42 which has a diameter similar to that of the other end land 37.
  • a stepped second pilot chamber housing 43 forms a second pilot chamber 44 into which the terminal land 42 is received, the second pilot chamber and land 42 being of similar diameter. Housing 43 also forms a slightly larger centering spring chamber 46 in the region of the reduced diameter section 41 of the spool.
  • a second pilot port 47 communicates with the second pilot chamber 44.
  • Spring centering means 48 are situated in chamber 46 to bias the spool 11 towards a predetermined centered position within the valve body 14 and may consist of a compression spring 49 acting between washers 51 and 52 which in turn abut against the lands 42 and 53 at the opposite ends of reduced diameter section 41 of the spool.
  • the spool Is biased towards a predetermined position at which the washers 51 and 52 are at their maximum possible travel in opposite directions. Movement of the valve spool 11 away from that position in either direction is increasingly resisted by the spring.
  • An infinitely variable three-position manually operated pilot valve 54 enables an operator to transmit pressurized fluid to either pilot chamber 38 or 44 while draining fluid from the other pilot chamber in order to shift the valve spool 11 a selected amount.
  • Pilot fluid under pressure is supplied to the pilot valve 54 by an additional pump 56 and the magnitude of the pilot fluid pressure is established by another relief valve 57 connected between the outlet of pump 56 and reservoir 23.
  • this form of pilot system is but one example of power-boosted means suitable for controlling the position of the valve spool.
  • Other examples of suitable pilot systems and servo systems for this purpose are known to the art.
  • a series of coaxial spaced-apart annular grooves 59, 61, 62, 63 and 64, are provided on the valve spool 11.
  • Groove 59 is located on the spool to bridge and communicate valve chambers 21 and 34 when the spool is at the above-described normal or centered position.
  • the next groove 61 is located to bridge and communicate valve chambers 21 and 33 at the same position of the spool.
  • Spool groove 62 separated from groove 61 by another land 67, is located at valve chamber 32 when the spool is in the normal position and serves to communicate service chamber 28 with drain chamber 32 when the spool is shifted a small distance to the right (as viewed in Figure 1) from the normal position.
  • Spool groove 63 separated from groove 62 by a relatively long land 68, is located at inlet chamber 19 when the spool is in the normal position and serves to communicate the inlet chamber 19 with service chamber 27 when the spool is shifted a small distance to the right and also to communicate the inlet chamber with the other service chamber 28 when the spool is shifted a corresponding distance to the left from the normal position.
  • the final spool groove 64 is separated from groove 63 by still another land 69 and is adjacent to the end land 37.
  • Spool groove 64 is situated at drain chamber 36 at the normal position of the spool and acts to communicate service chamber 27 with the drain chamber 36 when the spool is shifted a small distance to the left.
  • the control valve 12 is of the open-centered type.
  • the spring centering means 48 holds the spool 11 at the normal position at which spool lands 68 and 69 block the fluid inlet chamber 19 from both service chambers 27 and 28 and also block the service chambers from the adjacent drain chambers 32 and 36 to immobilize the fluid cylinder 13.
  • the output flow from pump 18 is returned to reservoir 23 through spool grooves 59 and 61, drain chambers 33 and 34, and drain port 29.
  • the pump 18 is opened to reservoir 23 when the control valve 12 is in the "Hold" position conserves energy relative to a closed-centered valve as it is not necessary for the pump 18 and the motor which drives the pump to dissipate energy by forcing fluid through the high resistance relief valve 22 at times when the fluid cylinder 13 is immobilized.
  • pilot valve 54 is operated to shift the valve spool 11 to the left as viewed in Figure 1, cylinder 13a is caused to extend as spool groove 63 then communicates inlet chamber 19 with the service chamber 28 which is in turn communicated with the head end of the cylinder. Concurrently the spool groove 64 communicates the service chamber 27 with drain groove 36 to release fluid from the rod end of the motor cylinder. If the pilot valve 54 is operated to shift the spool 11 rightwardly from the normal or "Hold" position depicted in Figure 1, the cylinder 13 is caused to retract since spool groove 63 then communicates inlet chamber 19. with service chamber 27 while spool groove 62 communicates the other service chamber 28 with drain chamber 32.
  • metering slots 71a to 71d are provided in the spool.
  • metering slots 71a are provided at opposite sides of the spool in the region of groove 59 and the adjacent land 66 while a second pair of metering slots 71b are similarly situated at groove 61 and the adjacent end of land 66.
  • a third pair of the metering slots 71c are located at groove 62 and the adjacent portion of land 68.
  • the basic function of such metering slots 71 is to cause the effective size of the flow path between two adjacent valve members to enlarge or decrease relatively gradually as the spool is traveled within the valve body.
  • the metering slots 71 of spool 11 serve this basic function but also have a specialized configuration to be hereinafter described which acts to reduce fluid flow reaction forces on the valve spool.
  • a metering action is also desirable between the service port 27 and drain chamber 36 when the valve spool 11 is moved leftwardly but the metering slots 72 in this case need not necessarily have the specialized force compensating configuration of slots 71.
  • the fluid which is metered out of the rod end of the cylinder 13 through service chamber 27 into drain chamber 36 is not under high pressure and therefore does not generate particularly high reaction forces on the spool.
  • four metering slots 72 extend from the center of groove 64 a distance into the adjacent end of land 69 but may be of, conventional configuration. The reason that only relatively low fluid pressure drops occur through metering slots 72 is that the working stroke of fluid cylinder 13, during which it is acting to raise a heavy load against gravity, occurs during cylinder extension in this particular examples.
  • a high fluid pressure may be present in the head end of the cylinder and correspondingly large pressure drop occurs through metering slot 71c
  • the flow through metering slot 71c can generate very high reaction forces on the spool and the specialized metering slot configuration is therefore employed.
  • the specialized metering slot configuration is also employed at slots 71a and 71b since the high pressure output of pump 18 must be throttled at those slots as the spool 11 is shifted to close the drain passages 33 and 34 off from the inlet port 17. Again, high reaction forces on the spool can be produced at these points.
  • each of the sets of force compensating metering slots 71a, 71b and 71c may be similar and accordingly only slots 71b will be described in detail as a representative example.
  • FIGs 2, 3 and 4 in conjunction, the portion of the valve spool 11 in the region of groove 61 is depicted In enlarged form.
  • the walls. of spool groove 61 are defined by the end surfaces 73 and 74 of the lands 66 and 67, respectively.
  • the inclination of end surface 73 of the first land 66, relative to the axial centerline 76 of the spool, is not critical and in this instance end surface 73 is substantially at right angles to the axis of the spool.
  • the inclination of the end surface 74 of the second land 67, at least at the radially outermost portion thereof, is significant as it defines the angle at which fluid is discharged from the spool groove 61.
  • At least the outermost portion of end wall 74 has a predetermined inclination relative to the spool axis that is selected for the purpose of reducing flow reaction forces on the spool by establishing a counter reaction force which opposes the reaction force generated at the other or fluid entrance end of the slot 71.
  • this inclination of the outermost portion of the land end surface 74 should be about 69° relative to the centerline 76 of the spool axis to cause the angle of discharge of fluid from the spool groove 61 to correspond to the effective angle of entry of the fluid into the opposite end of the slot 71b.
  • Each metering slot 71b has a fluid entrance end 77 extending a distance into the adjacent first land 66 through end surface 73 of that land with the fluid entrance end of the slot being of circular profile in this example.
  • the fluid entrance end 77 is continuous with a central section 79 of the metering slot which is cut into the base of groove 61.
  • the central section 79 curves outwardly towards the fluid discharge end 78 of the slot with a curvature which causes the slot to direct fluid along a discharge path 78 extending outwardly along the conical surfaced end wall 74 of land 67 at the above-described angle.
  • the metering slot 71b may simply merge tangentially with the end wall 74, preferably at a radially intermediate point thereon, manufacturing is facilitated if the discharge path 78' is defined by a shallow extension of the slot extending along the outermost portion of end wall 74 to the periphery of land 67 as Is visible in Figure 2.
  • the slight indentation thus formed at the edge of the land 67 provides a convenient reference point for quality control checking of tolerances.
  • two additional metering slots 81 are provided, each extending from the central region of spool groove 61 into the adjacent portion of land 66 but not as far as the slots 71b extend into that land.
  • the additional slots 81 which may be of conventional configuration, provide for a larger flow passage of less flow resistance at times when the spool has been shifted a substantial distance to the left.
  • the groove 61 may be formed by mounting round bar work stock 82 in a lathe, preferably a tracer lathe, and operating a first cutting tool 83 controlled by the lathe to form spool groove 61 with the previously described configuration including forming the conical ramp end wall surface 74 at one end of the groove.
  • the metering slots 71 may then be formed by using a key-way cutter 86 of the type having a rotary disc cutting tool 87 which may be advanced radially inward towards the axis of the work stock while being rotated to cut the slot.
  • Key-way cutters 86 of this type readily enable the precise locating of the fluid entrance end 77 of the slot on the spool.
  • the axial position of the conical ramp surface 74 has already been determined by the previously described steps.
  • the metering slot 71b may therefore be completed by traveling the rotating disc cutting tool 87 or alternately the work stock 82 in an axial direction and by terminating such travel after the cutting edge of the circular cutting tool 87 comes into tangency with the pre-existing ramp surface 74, preferably after it has cut a slight distance into the ramp surface 74 so that by withdrawing the tool 87 in a direction parallel to the ramp surface, the shallow discharge path groove 78' is formed therein.
  • pilot valve 54 In operation, positioning of the pilot valve 54 to the "Hold" position depicted in Figure 1 vents both pilot chambers 38 and 44 to reservoir 23 allowing spring centering means 48 to maintain spool 11 at the depicted centered position. At that spool position, there is no fluid flow to or from either end of cylinder 13. The output of pump 18 is released back to the reservoir 23 as drain chambers 33 and 34 are both communicated with the flow return chamber 21 through spool grooves 61 and 59 respectively. No large pressure drop is occurring at any of the spool grooves and flow reaction force, if any, on the spool is minimal.
  • pilot valve 54 When pilot valve 54 is operated to transmit pilot pressure to pilot chamber 44 while releasing fluid from pilot chamber 38, the spool 11 is traveled to the right. After an initial amount of such travel, land 69 opens inlet chamber 19 to service chamber 27 admitting pressurized fluid to the rod end of cylinder 13.
  • metering slots 71c begin to communicate the head end of the cylinder 13 with drain chamber 32 although the initial flow aperture to drain is small. Also at this time, land 53 blocks the flow return chamber 21 from drain chamber 34 while land 63 begins to close off chamber 21 from drain chamber 33 although the metering slots 71b continue to provide a reduced flow path therebetween.
  • the external load forces tend to retract the cylinder 13 (the cylinder may, for example, be one which lowers the bucket of a loader vehicle during the retraction stroke).
  • the rate of cylinder retraction Is basically determined by the degree of discharge flow restriction at metering slots 71c. Cylinder retraction rate may be increased by shifting spool 11 further to the right to enlarge the effective discharge passage from chamber 28 to chamber 32 through metering slots 71c which spool movement also concurrently further restricts the flow passage from chamber 21 to drain chamber 33 through metering slots 71b to accommodate to the increased working fluid flow to the rod end of the cylinder.
  • the force compensating metering slots such as slots 71c substantially reduce the net flow reaction forces exerted against the spool 11.
  • the effective entrance angle of the flow being metered in at this entrance end 77 of metering slots 71b is about 69° and this produces a redaction force on the spool, having an axial component, tending to urge the spool to the left.
  • the fluid then travels through the discharge ends 78 of slots 71b and out ramp surface 74 to exit from the groove 61 at substantially the same angle creating an oppositely directed reaction force on the spool which reduces the net flow force acting on the spool.
  • slots 72a may be of the conventional configuration. Slots 71a at groove 59 do experience a sizable pressure drop at this time, in the course of throttling the flow of working fluid from pump 18 Into drain chamber 34, and are therefore also of the force compensating specialized configuration.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Sliding Valves (AREA)

Abstract

Les forces de reaction au courant fluide dirige axialement sur le tiroir d'une vanne (11) sont reduites par la configuration de la gorge du tiroir (61) et de la rainure de fuite (71b) qui force le fluide quittant une gorge du tiroir dans une inclinaison predeterminee selectionnee pour reduire la force de reaction de courant sur le tiroir. De preference l'angle de sortie correspond a l'angle effectif auquel le fluide est circule a l'extremite d'entree (77) de la rainure de fuite. Le maintien du tiroir dans une position determinee et son deplacement necessitent moins d'efforts mecaniques et la vanne est moins sensible a des changements de pression dans la gorge. Le controle precis de l'angle de sortie du fluide est prevu pendant la fabrication en tournant premierement une rampe de sortie conique dans une des parois (74) de la gorge du tiroir ayant l'inclinaison selectionnee.
PCT/US1978/000116 1978-10-23 1978-10-23 Tiroir de vanne a faible reaction a rainures de fuites et procede de fabrication WO1980000870A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1978/000116 WO1980000870A1 (fr) 1978-10-23 1978-10-23 Tiroir de vanne a faible reaction a rainures de fuites et procede de fabrication

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
WOUS78/00116 1978-10-23
PCT/US1978/000116 WO1980000870A1 (fr) 1978-10-23 1978-10-23 Tiroir de vanne a faible reaction a rainures de fuites et procede de fabrication

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WO1980000870A1 true WO1980000870A1 (fr) 1980-05-01

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0137779A1 (fr) * 1983-02-25 1985-04-24 Caterpillar Tractor Co Configuration de la fente de mesure pour soupapes de commande hydraulique.
US5329841A (en) * 1991-03-14 1994-07-19 Hydraulik-Ring Gmbh Piston-slide-valve
AT413052B (de) * 1999-10-22 2005-10-15 Bosch Rexroth Ag Hydraulisches antriebssystem und darin verwendbares hydraulisches 4/3-wegeventil
WO2017182759A1 (fr) * 2016-04-21 2017-10-26 Safran Aircraft Engines Tiroir pour vanne de circuit de carburant d'un moteur d'aeronef
JP2018013184A (ja) * 2016-07-21 2018-01-25 株式会社デンソー スプール弁
CN111853282A (zh) * 2019-04-30 2020-10-30 博世力士乐（常州）有限公司 液压换向阀

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3198212A (en) * 1963-05-22 1965-08-03 Caterpillar Tractor Co Metering slot configuration for hydraulic control valves
US3556155A (en) * 1969-01-24 1971-01-19 Caterpillar Tractor Co Variable flow-modulated valve
US4155535A (en) * 1977-03-09 1979-05-22 The Johns Hopkins University Low axial force servo valve spool

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3198212A (en) * 1963-05-22 1965-08-03 Caterpillar Tractor Co Metering slot configuration for hydraulic control valves
US3556155A (en) * 1969-01-24 1971-01-19 Caterpillar Tractor Co Variable flow-modulated valve
US4155535A (en) * 1977-03-09 1979-05-22 The Johns Hopkins University Low axial force servo valve spool

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0137779A4 (fr) * 1983-02-25 1985-07-30 Caterpillar Tractor Co Configuration de la fente de mesure pour soupapes de commande hydraulique.
EP0137779A1 (fr) * 1983-02-25 1985-04-24 Caterpillar Tractor Co Configuration de la fente de mesure pour soupapes de commande hydraulique.
US5329841A (en) * 1991-03-14 1994-07-19 Hydraulik-Ring Gmbh Piston-slide-valve
AT413052B (de) * 1999-10-22 2005-10-15 Bosch Rexroth Ag Hydraulisches antriebssystem und darin verwendbares hydraulisches 4/3-wegeventil
CN109073100A (zh) * 2016-04-21 2018-12-21 赛峰飞机发动机公司 飞机引擎燃料回路阀滑块
WO2017182759A1 (fr) * 2016-04-21 2017-10-26 Safran Aircraft Engines Tiroir pour vanne de circuit de carburant d'un moteur d'aeronef
FR3050508A1 (fr) * 2016-04-21 2017-10-27 Snecma Tiroir pour vanne de circuit de carburant d'un moteur d'aeronef
US10760696B2 (en) 2016-04-21 2020-09-01 Safran Aircraft Engines Aircraft engine fuel circuit valve slide
JP2018013184A (ja) * 2016-07-21 2018-01-25 株式会社デンソー スプール弁
CN109312868A (zh) * 2016-07-21 2019-02-05 株式会社电装 滑阀
CN109312868B (zh) * 2016-07-21 2020-05-05 株式会社电装 滑阀
KR20180125588A (ko) * 2016-07-21 2018-11-23 가부시키가이샤 덴소 스풀밸브
KR102157325B1 (ko) * 2016-07-21 2020-09-17 가부시키가이샤 덴소 스풀밸브
US10781928B2 (en) 2016-07-21 2020-09-22 Denso Corporation Spool valve
CN111853282A (zh) * 2019-04-30 2020-10-30 博世力士乐（常州）有限公司 液压换向阀

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