US3722547A - Pilot valve - Google Patents

Pilot valve Download PDF

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Publication number
US3722547A
US3722547A US3722547DA US3722547A US 3722547 A US3722547 A US 3722547A US 3722547D A US3722547D A US 3722547DA US 3722547 A US3722547 A US 3722547A
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United States
Prior art keywords
piston
recess
shoulder
pilot valve
pilot
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 - Lifetime
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English (en)
Inventor
L Kirstein
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Jos Schneider Optische Werke GmbH
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Jos Schneider Optische Werke GmbH
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Assigned to JOS. SCHNEIDER OPTISCHE WERKE AKTIENGESELLSCHAFT reassignment JOS. SCHNEIDER OPTISCHE WERKE AKTIENGESELLSCHAFT CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE JULY 30, 1981 Assignors: JOS. SCHNEIDER GMBH & CO. OPTISCHE WERKE
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Expired - Lifetime legal-status Critical Current

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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
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/86582—Pilot-actuated
    • Y10T137/86606—Common to plural valve motor chambers

Definitions

  • Attorney PILOT VALVE My present invention relates to a pilot valve wherein a main or working piston, controlling the flow of a hydraulic or pneumatic working fluid to a load, is hydraulically or pneumatically positionable with the aid of a smaller pilot piston responding to a controlling force.
  • the axial shifting of the main piston in its cylindrical housing is effected by the pressure of a pilot fluid acting upon an external peripheral shoulder of that piston, this pressure being derived from a throttled fluid path between an inlet and an outlet port and being therefore a fraction of the supply pressure available at the inlet port which may or may not be the same as the delivery pressure of the working fluid.
  • this piston is subjected to the action of biasing means tending to immobilize it in the housing.
  • the biasing force may be derived from the inlet pressure of the pilot fluid with the aid of a conduit opening onto a land of the main piston facing in the direction opposite that of the aforementioned peripheral shoulder.
  • the general object of my invention is to provide a compact valve construction in which the working piston is of small axial length and isprovided with a simple channel system traversed by the pilot fluid, this system being constituted by a set of short bores than can be easily' machined.
  • an extremity of the main piston is provided with an axial bore accommodating the pilot piston, this extremity also carrying the aforementioned peripheral shoulder dividing it into an enlarged and a reduced portion.
  • the reduced portion is engaged by a sealing member on the housing, such as a metal ring, to define a variablevolume fluid chamber to which pilot fluid is admitted via a branch of its throttled path.
  • a part of this path is constituted by an oblique passage in the shouldered extremity of the main piston, this passage communicating with a peripheral recess of the pilot piston bounded by two axially spaced heads thereof; the oblique passage terminates at opposite sides of a transverse plane through the peripheral shoulder, thereby establishing a short connection between that recess and either the above-identified fluid chamber or one of the ports of the pilot path.
  • This arrangement reduces the volume of the variable chamber, which is permanently filled with the pilot fluid (e.g. oil), with resulting improvement in the dynamic response of the valve.
  • the fractional pressure prevailing in that chamber allows the use of a narrow sealing surface with consequent lowering of frictional resistance, increased sensitivity and reduced hysteresis.
  • the pilot piston is hollow so as to form a throughgoing channel which equalizes the pressure at opposite ends thereof in the axial bore of the main piston.
  • FIG. 1 is an axial sectional view of a first embodiment of my invention
  • FIG. la is an enlarged sectional detail view of some of the elements shown in FIG. 1;
  • FIG. lb is a cross-sectional view taken on the line IBIB of FIG. la;
  • FIG. 1c is a partial flow diagram for the system of FIG. 1;
  • FIG. 2 is a view similar to FIG. 1, showing a second embodiment
  • FIG. 2a is a detail view analogous to FIG. la but relating to the system of FIG. 2;
  • FIG. 2b is a cross-sectional view taken on the line IIB-IIB of FIG. 2a.
  • the pilot valve shown in FIG. 1 comprises a cylindrical housing 1 with end walls 24, 26 secured thereto by bolts 35, 36.
  • a guide sleeve 3 within the housing surrounds a working piston 4 which is axially slidable therein to admit oil or some other working fluid to a load 37 via one of two ports 38, 39, both ports being cut off in the illustrated centered piston position in which two axially spaced piston heads 4a, 4b obstruct a pair of apertures 10, 11 in sleeve 3 respectively communicating with these ports via ring channels 40, 41.
  • the working fluid delivered by a pump enters the housing 1 from the outer surface 2 thereof, as indicated diagramatically by an arrow E, and passes through a further ring channel 42 into an annular recess 43 bounded by piston heads 4a and 4b. With the piston 4 shifted either to the left or to the right, this high-pressure fluid reaches the load 37 through a corresponding entrance duct 380 or 39a to displace it in one sense or the other.
  • Ring channels 40, 41, 42 are formed by complementary annular grooves in housing 1 and sleeve 3, as are a pair of further ring channels 44, 45 communicating with a low-pressure region or sump via respective discharge ducts diagramatically indicated by arrows D and D. It will be apparent that the establishment of a connection from inlet port 8 to one of the two conjugate working ports 38, 39 places the other of these ports in communication with outlet port 9 or 9' via an associated further peripheral recess 46, 47 of piston 4.
  • the left-hand extremity of the main piston 4 (as viewed in FIG. 1) is formed with an axial bore 18 accommodating a pilot piston 7, the latter being integral with a stem 21 passing outwardly through wall 26 by way of an enlarged extension 19 of bore 18.
  • Stem 21 is axially shiftable, as indicated by an arrow C, in response to an external controlling force (e.g. that of a solenoid) to displace the piston 7 which has three axially spaced heads 7a, 7b, (see particularly FIG. la) in sliding contact with the wall of bore 18.
  • this left-hand extremity is divided by a peripheral shoulder A into a reduced portion 4' and a relatively enlarged portion 4 the latter forming one of the boundaries of peripheral recess 46.
  • This recess which through port 9 communicates with the low-pressure side of the nonillustrated pump delivering the working fluid to inlet port 8, is connected through a pair of radial bores 14 in piston 4 with a peripheral recess 48 of piston 7 bounded by heads 7b and 7c thereof.
  • a similar recess 49 lies between piston heads 7a and 7b at the left of a transverse plane, coinciding with the section line IB-IB in FIG. la, which passes through the shoulder A.
  • Recess 49 is open toward an oblique bore 13 in the body of piston 4 traversing the plane IB-IB and terminating at a ring channel 50 which communicates with a conduit 12 in housing 1, this conduit in turn being joined to inlet port 8 (as diagramatically indicated in FIG. 10) so as to carry the delivery pressure of the supply pump.
  • the middle piston head 7b has a width slightly less than the diameter d of an adjoining radial bore 16 which traverses the piston 4 and terminates at a chamber 51 of variable volume bounded by shoulder A and by a sealing ring 5a forming part of a metallic annular profile 5.
  • two narrow clearances 27 and 28 are thereby left at opposite sides of head 7b to provide throttled fluid passages of a width equaling each onethirtieth the size of diameter d.
  • piston 7 has an axial bore 55, surrounding the stem 21 with clearance, and a pair of transverse bores 56 connecting; bore 55 with a similar bore 57 at the free end of the stem, thereby equalizing the pressure on opposite sides of that piston.
  • both ends of the two pistons 4 and 7 are always under atmospheric or sump pressure.
  • bore 16 and passage 13 lie in mutually perpendicular planes even though, for convenience, they have been shown coplanar in FIGS. 1 and 1a.
  • Radial bores 14 and 56 lie in the same plane as the oblique passages 13.
  • any unbalancing of the system by a shift of piston 7 to the left from its normal position relative to piston 4 reduces the clearance 27 and increases the clearance 28, thereby lowering the fractional pressure prevailing in bores 16 and chamber 51.
  • the right-hand conduit 39a is vented to the sump through ports 39 and 9'.
  • FIGS. 2, 2a and 2b I have shown a partial modification of the system described above, corresponding elements having been designated by the same or analogous reference characters.
  • the smalldiameter portion 104' and the large-diameter portion 104" of piston 104 are separated by a shoulder A lying in a transverse plane parallel to section line IIB-IIB, in lieu of the frustoconical shoulder A of the first embodiment.
  • the single pair of aligned radial bores 16, coacting in that embodiment with the middle head 7b of a three-headed pilot piston 7, has been replaced by two pairs of axially spaced bores 33, 34 co-operating with respective heads 7a, 7b of a two-headed pilot piston 7'.
  • bores 34 lie in a plane perpendicular to that of a pair of oblique passages 13', one of these passages having been turned into the plane of the bores (with one bore 34 omitted) in FIGS. 2 and 2a to simplify the drawing.
  • the internal construction of piston 7 and its connection with stem 21 is similar to that of piston 7 in the preceding Figures.
  • high-pressure fluid enters a pair of radial bores 29 in sleeve 3 through the housing 1 and is drained to the sump by way of similar bores 30 which are axially offset therefrom.
  • Piston portion 104" has two axially spaced peripheral recesses 50, 50" respectively communicating with bores 29 and 30. These bores may be included in a fluid circuit independent of that for the working medium, with a supply pressure unaffected by possible pressure variations in the load circuit; if this separation is not necessary, however, bore 29 may also communicate with bore 8 via internal channels not shown.
  • the oblique passages 13' constitute the branch of the pilot-fluid path serving for the transmission of the fractional fluid pressure to piston shoulder A.
  • the system of FIG. 2 responds to a displacement of stem 21 in the same manner as that of FIG. 1.
  • FIGS. 1a and 2a can be machined in a simple manner and accommodated on a small part of the main piston 4 or 104, thanks mainly to the presence of the oblique passages 13 or 13' which terminate on opposite sides of a transverse plane passing through shoulder A or A.
  • This compact design also minimizes the axial length of the small-diameter piston portion 4' or 104' engaged by the seal 5, thereby also reducing the volume of the fluid chamber 51 or 51' subjected to fractional pressure.
  • the pressure in that chamber can be made as low as desired so that the contact area between the seal and the piston may also be small, along with the frictional resistance generated therein. This results in a highly sensitive value with minimum hysteresis.
  • a pilot valve comprising:
  • a cylindrical housing provided with a channel system for the flow of a working fluid to a load; main piston axially movable in said housing for selectively blocking and unblocking the flow of said working fluid, said main piston having an extremity provided with an axial bore and with an external peripheral shoulder in the region of said bore; sealing means in said housing bearing upon a reduced portion of said extremity and defining a fluid chamber with said shoulder;
  • pilot piston axially slidable in said bore, said pilot piston being provided with a plurality of heads defining at least one peripheral recess included in a throttled path extending between a high-pressure port and a low-pressure port with a branch terminating at said fluid chamber for exerting upon said shoulder a fractional fluid pressure controlled by the relative position of said pistons, said path including an oblique passage in said extremity communicating with said recess and terminating at opposite sides of a transverse plane through said shoulder; and
  • biasing means tending to immobilize said main piston in said housing.
  • a pilot valve as defined in claim I wherein said biasing means comprises a land on said piston facing in a direction opposite that of said shoulder, said land being subjected to a countervailing fluid pressure from said high-pressure port.
  • pilot piston has three axially spaced heads defining between them a first recess and a second recess, said first recess being open toward said passage and communicating therethrough with said high-pressure port, said second recess communicating with said low-pressure port, said branch bein a radial bore in said extremi y confronting the m1 dle one of said heads and defining two narrow clearances on opposite sides thereof in a normal relative position of said pistons.
  • a pilot valve as defined in claim 4 wherein said first recess is surrounded by said reduced portion of said extremity, said passage terminating at an enlarged portion separated by said shoulder from said reduced portion.
  • pilot valve as defined in claim 3 wherein said pilot piston has two axially spaced heads bounding said recess, said branch being constituted by said passage, said recess normally communicating with said ports via two radial bores in said extremity partly obstructed by' said heads with formation of two narrow clearances.
  • pilot valve as defined in claim 1 wherein said pilot piston has a throughgoing channel for equalizing the pressure in said axial bore at opposite ends thereof.
US3722547D 1970-10-21 1971-10-18 Pilot valve Expired - Lifetime US3722547A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702051582 DE2051582A1 (de) 1970-10-21 1970-10-21 Folgekolbenventil

Publications (1)

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US3722547A true US3722547A (en) 1973-03-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
US3722547D Expired - Lifetime US3722547A (en) 1970-10-21 1971-10-18 Pilot valve

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US (1) US3722547A (de)
CH (1) CH531131A (de)
DE (1) DE2051582A1 (de)
FR (1) FR2112323A1 (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3891145A (en) * 1972-07-27 1975-06-24 Rexroth Gmbh G L Hydraulic tracking valve for templates in machine tools or the like
US3949645A (en) * 1973-07-03 1976-04-13 Messier Hispano Distributing unit for a dual action hydraulic electro-distributor
US4545409A (en) * 1983-04-13 1985-10-08 Integral Hydraulik & Co. Electrohydraulic, two-stage, proportional displacement valve
US4620560A (en) * 1985-05-06 1986-11-04 Caterpillar Inc. Modulating relief valve with dual functioning load piston
US5445188A (en) * 1993-05-27 1995-08-29 Hydrolux S.A.R.L. Pilot operated servo valve
US20150260302A1 (en) * 2014-03-12 2015-09-17 Flextronics Automotive Inc. Dual/variable gain oil pump control valve
CN107795696A (zh) * 2016-09-02 2018-03-13 株式会社不二工机 控制阀
EP3301335A1 (de) * 2016-09-30 2018-04-04 Safran Aero Boosters SA Flüssigkeitsventil
WO2022144862A1 (en) * 2021-01-04 2022-07-07 Mohammad Durali Hydraulic directional control valve
US11619311B2 (en) * 2020-06-08 2023-04-04 The Boeing Company Flow control valve, a method of assembly, and a hydraulic system

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5316183A (en) * 1976-07-28 1978-02-14 Hitachi Ltd Fluid pressure driving device
DE3114437C2 (de) * 1981-04-09 1989-10-12 Mannesmann Rexroth GmbH, 8770 Lohr Druckregelventil
EP0088017B1 (de) * 1982-02-26 1987-11-19 COMPAGNIE PARISIENNE D'OUTILLAGE A AIR COMPRIME Société anonyme dite: Hydraulisches Wegeschieberventil
DE3313318A1 (de) * 1983-04-13 1984-10-18 Integral Hydraulik & Co, 4000 Düsseldorf Anordnung zur steuerkanteneinstellung eines folgekolben-systems

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3891145A (en) * 1972-07-27 1975-06-24 Rexroth Gmbh G L Hydraulic tracking valve for templates in machine tools or the like
US3949645A (en) * 1973-07-03 1976-04-13 Messier Hispano Distributing unit for a dual action hydraulic electro-distributor
US4545409A (en) * 1983-04-13 1985-10-08 Integral Hydraulik & Co. Electrohydraulic, two-stage, proportional displacement valve
US4620560A (en) * 1985-05-06 1986-11-04 Caterpillar Inc. Modulating relief valve with dual functioning load piston
US5445188A (en) * 1993-05-27 1995-08-29 Hydrolux S.A.R.L. Pilot operated servo valve
US20150260302A1 (en) * 2014-03-12 2015-09-17 Flextronics Automotive Inc. Dual/variable gain oil pump control valve
US9404599B2 (en) * 2014-03-12 2016-08-02 Flextronics Automotive Inc. Dual/variable gain oil pump control valve
CN107795696B (zh) * 2016-09-02 2020-12-04 株式会社不二工机 控制阀
CN107795696A (zh) * 2016-09-02 2018-03-13 株式会社不二工机 控制阀
EP3301335A1 (de) * 2016-09-30 2018-04-04 Safran Aero Boosters SA Flüssigkeitsventil
CN107883014A (zh) * 2016-09-30 2018-04-06 赛峰航空助推器有限公司 流体阀
BE1024622B1 (fr) * 2016-09-30 2018-05-24 Safran Aero Boosters S.A. Vanne fluidique
US10760707B2 (en) 2016-09-30 2020-09-01 Safran Aero Boosters S.A. Fluid valve
CN107883014B (zh) * 2016-09-30 2020-12-15 赛峰航空助推器有限公司 流体阀
US11619311B2 (en) * 2020-06-08 2023-04-04 The Boeing Company Flow control valve, a method of assembly, and a hydraulic system
WO2022144862A1 (en) * 2021-01-04 2022-07-07 Mohammad Durali Hydraulic directional control valve

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Publication number Publication date
FR2112323A1 (de) 1972-06-16
DE2051582A1 (de) 1972-07-06
CH531131A (de) 1972-11-30

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Legal Events

Date Code Title Description
AS Assignment

Owner name: JOS. SCHNEIDER OPTISCHE WERKE AKTIENGESELLSCHAFT

Free format text: CHANGE OF NAME;ASSIGNOR:JOS. SCHNEIDER GMBH & CO. OPTISCHE WERKE;REEL/FRAME:003925/0522

Effective date: 19810730