US3815477A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control valve instrumentality
Assignee: CROSS Manufacturing Inc
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Filing: 1973-02-06
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Granted: 1974-06-11
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Expires: 1993-02-06
Abstract
Abstract An open center directional control valve assembly having an unloading valve that diverts inlet flow to drain without passing through the entire assembly whenever all control valves are in neutral. When one or more of the control valves are operative, to actuate their associated motors at desired speeds, the unloading valve is automatically positioned by the pressure difference between inlet pressure and the highest motor pressure to deliver the necessary flow to operate the motors at the desired speeds while diverting the remainder of inlet flow to drain.
Inventors
- 👤 R Ailshie
- 👤 Millen K Mc
- 👤 Millen L Mc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:40
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/161; F15B11/163; F15B13/00; F15B13/02; F15B13/04; F15B13/0416; F15B13/0417; F15B2211/00; F15B2211/30; F15B2211/31; F15B2211/3105; F15B2211/3116; F15B2211/40; F15B2211/405; F15B2211/40507; F15B2211/40515; F15B2211/40576; F15B2211/40584; F15B2211/455; F15B2211/47; F15B2211/473; F15B2211/50; F15B2211/505; F15B2211/50509; F15B2211/50518; F15B2211/50536; F15B2211/55; F15B2211/57; F15B2211/70; F15B2211/71; F15B2211/75; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/87169; Y10T137/87177; Y10T137/87185
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
438 words
In a hydraulic system having a source of pressure fluid, a low pressure reservoir, and a hydraulic motor connected with said source: an unloading valve communicating with said source and said reservoir to allow direct flow therebetween bypassing said motor, said unloading valve having a bore therein closed at both ends; a shiftable spool movably disposed in said bore for controlling said bypass flow from the source to reservoir and defining pressure chambers at opposite ends of said bore, said unloading valve having a duct providing flow from said source to one of said chambers whereby pressure therein urges said spool toward an unloading position connecting said source with the reservoir; biasing means disposed in the other of said pressure chambers for urging said spool toward a position variably blocking communication between said source and said reservoir and thereby adjusting the rate of flow from said source to said motor; a directional control valve interposed in the path of fluid flow from said source to said motor downstream of said unloading valve and communicating with the reservoir, said control valve having a first pilot passage connectable with the reservoir and a second pilot passage connectable with the motor, said first and second pilot passages communicating with said other pressure chamber of the unloading valve; and a shiftable member mounted in said control valve for controlling communication between said source and said motor and intercepting said first and second pilot passages, said member having a neutral position blocking flow from said source to said motor and blocking communication between said second pilot passage and said motor while connecting said first pilot passage with the reservoir to thereby maintain low pressure in said other pressure chamber and allow pressure in said one pressure chamber to overcome the urgings of said biasing means and shift said spool to said unloading position thereof, said member being selectively shiftable from said neutral position to an operating position establishing a variable size orifice of communication between said source and said motor to select speed of operation of the latter, said member in said operating position blocking communication between said first pilot passage and the reservoir while connecting said second pilot passage with said motor downstream of said orifice to transmit the pressure existing downstream of the orifice to said other pressure chamber to assist said biasing means in urging said spool to said variably blocking position, whereby said spool is positioned to maintain a substantially constant pressure differential across said variable size orifice and allow delivery of fluid to said control valve and motor at a rate operating said motor at said selected speed.
Claim 2
Dependent Claim
438 words
In a hydraulic system having a source of pressure fluid, a low pressure reservoir, and a hydraulic motor connected with said source: an unloading valve communicating with said source and said reservoir to allow direct flow therebetween bypassing said motor, said unloading valve having a bore therein closed at both ends; a shiftable spool movably disposed in said bore for controlling said bypass flow from the source to reservoir and defining pressure chambers at opposite ends of said bore, said unloading valve having a duct providing flow from said source to one of said chambers whereby pressure therein urges said spool toward an unloading position connecting said source with the reservoir; biasing means disposed in the other of said pressure chambers for urging said spool toward a position variably blocking communication between said source and said reservoir and thereby adjusting the rate of flow from said source to said motor; a directional control valve interposed in the path of fluid flow from said source to said motor downstream of said unloading valve and communicating with the reservoir, said control valve having a first pilot passage connectable with the reservoir and a second pilot passage connectable with the motor, said first and second pilot passages communicating with said other pressure chamber of the unloading valve; and a shiftable member mounted in said control valve for controlling communication between said source and said motor and intercepting said first and second pilot passages, said member having a neutral position blocking flow from said source to said motor and blocking communication between said second pilot passage and said motor while connecting said first pilot passage with the reservoir to thereby maintain low pressure in said other pressure chamber and allow pressure in said one pressure chamber to overcome the urgings of said biasing means and shift said spool to said unloading position thereof, said member being selectively shiftable from said neutral position to an operating position establishing a variable size orifice of communication between said source and said motor to select speed of operation of the latter, said member in said operating position blocking communication between said first pilot passage and the reservoir while connecting said second pilot passage with said motor downstream of said orifice to transmit the pressure existing downstream of the orifice to said other pressure chamber to assist said biasing means in urging said spool to said variably blocking position, whereby said spool is positioned to maintain a substantially constant pressure differential across said variable size orifice and allow delivery of fluid to said control valve and motor at a rate operating said motor at said selected speed.
Claim 3
Dependent Claim
123 words
A hydraulic system as set forth in claim 1, wherein is provided a plurality of said hydraulic motors connected in parallel with said source downstream of said spool and a plurality of said directional control valves and corresponding shiftable members for controlling operation of said motors, said first pilot passages of said control valves being connected in series whereby shifting of any of said members away from its neutral position blocks communication of said other pressure chamber with the reservoir through said first pilot passages, said second pilot passages of said control valves being connected with said other pressure chamber in parallel arrangement whereby the highest pressure existing at said motors is transmitted by said second pilot passages to said other pressure chamber.
Claim 4
Dependent Claim
63 words
A hydraulic system as set forth in claim 2, wherein is provided a check valve in each of said second pilot passages allowing relatively free fluid flow from the assoCiated motor to said other pressure chamber while severely restricting fluid flow through said second pilot passage in the opposite direction to reduce direct fluid flow between said motors through said second pilot passages.
Claim 5
Dependent Claim
90 words
A hydraulic system as set forth in claim 3, wherein is provided a common duct connected with said other pressure chamber, said second pilot passages being connected in parallel with said common duct, each of said check valves comprising a hexagonal element having an orifice passage therethrough and shiftably disposed in the corresponding second pilot passage to allow relatively free flow from said motor to said common duct past the periphery of said hexagonal element while permitting flow from said common duct to said motor only through said orifice passage.
Claim 6
Dependent Claim
74 words
A hydraulic system as set forth in claim 1, wherein said unloading valve has a second duct connecting said source with said other pressure chamber, and means in said second duct for restricting flow therethrough whereby low pressure is maintained in said other pressure chamber when said control member is in its neutral position and pressure at said motor is maintained in said other chamber when said control member is in its operation position.
Claim 7
Dependent Claim
60 words
A hydraulic system as set forth in claim 5, wherein is included a high pressure relief valve communicating with said other pressure chamber and the reservoir, said relief valve being operable to open and relieve pressure from said other chamber to allow said spool to move to said unloading position when pressure in said other chamber exceeds a predetermined level.
Claim 8
Dependent Claim
49 words
A hydraulic system as set forth in claim 6, wherein is provided a check valve between said second pilot passage and said other chamber for preventing fluid flow from said motor to said other pressure chamber while allowing pressure at said motor to be transmitted to said other chamber.
Claim 9
Dependent Claim
37 words
A hydraulic system as set forth in claim 5, wherein said first mentioned duct and said second duct are separate internal passages in said spool respectively connecting said one and said other pressure chambers with said source.
Claim 10
Dependent Claim
77 words
A hydraulic system as set forth in claim 1, wherein said control valve includes a port communicating with said motor, said second pilot passage including a duct in said control valve communicating with said other pressure chamber and intercepted by said control member, said second pilot passage further including an internal passage in said control member which registers with said motor port and said duct in the control valve upon shifting said member to its operating position.
Claim 11
Dependent Claim
100 words
A hydraulic system as set forth in claim 9, wherein said control valve includes a pair of ports communicating with opposite sides of said motor, said control member being shiftable in opposite directions away from neutral to establish variable size orifices of communication between said source and said motor ports, said second pilot passage including a pair of said internal passages in said control member respectively registering with said pair of motor ports as said member is shifted in opposite directions away from neutral to connect said other pressure chamber with said motor port that is communicating with said source.
Claim 12
Dependent Claim
377 words
A control valve for a hydraulic system including a fluid actuated motor, a fixed displacement source of pressure fluid, and a reservoir, said control valve comprising: a housing having first and second spaced longitudinal bores, a generally transverse inlet passage connected to said source and sequentially intercepting said first and second bores, an exhaust passage communicating with the reservoir and intercepting said first bore adjacent said inlet passage, a motor passage connected with said motor and intercepting said second bore adjacent said inlet passage, and first and second pilot passages intercepted by said second bore, said first passage being connected with the reservoir; a pressure responsive spool disposed in said first bore and shIftable to variably restrict fluid flow from said inlet passage to said exhaust passage and thereby vary the rate of flow delivered through said inlet passage to said second bore; means for supplying pressure from said source to one end of said pressure responsive spool to urge the latter to an unloading position permitting free fluid flow from said inlet passage to said exhaust passage; biasing means acting against the opposite end of said pressure responsive spool to urge the latter towards positions variably metering flow from the inlet to the exhaust passages; a manually shiftable control spool in said second bore having a neutral position blocking said inlet passage while connecting said first pilot passage with the reservoir, and an operating position establishing a variable orifice of communication between said inlet passage and said motor passage to control speed of operation of the motor while connecting said second pilot passage with said motor passage downstream of said variable orifice and blocking communication of said first pilot passage with the reservoir; and means connecting said first and second pilot passages with said opposite end of the pressure responsive spool whereby to maintain low pressure of the reservoir at said opposite end when said manual control spool is in its neutral position and to transmit pressure from said motor passage downstream of said variable orifice to said opposite end to assist said biasing means in moving said pressure responsive spool to said variable metering positions when said manual control is in its operating position to maintain a substantially constant pressure differential across said variable orifice.
Claim 13
Dependent Claim
377 words
A control valve for a hydraulic system including a fluid actuated motor, a fixed displacement source of pressure fluid, and a reservoir, said control valve comprising: a housing having first and second spaced longitudinal bores, a generally transverse inlet passage connected to said source and sequentially intercepting said first and second bores, an exhaust passage communicating with the reservoir and intercepting said first bore adjacent said inlet passage, a motor passage connected with said motor and intercepting said second bore adjacent said inlet passage, and first and second pilot passages intercepted by said second bore, said first passage being connected with the reservoir; a pressure responsive spool disposed in said first bore and shIftable to variably restrict fluid flow from said inlet passage to said exhaust passage and thereby vary the rate of flow delivered through said inlet passage to said second bore; means for supplying pressure from said source to one end of said pressure responsive spool to urge the latter to an unloading position permitting free fluid flow from said inlet passage to said exhaust passage; biasing means acting against the opposite end of said pressure responsive spool to urge the latter towards positions variably metering flow from the inlet to the exhaust passages; a manually shiftable control spool in said second bore having a neutral position blocking said inlet passage while connecting said first pilot passage with the reservoir, and an operating position establishing a variable orifice of communication between said inlet passage and said motor passage to control speed of operation of the motor while connecting said second pilot passage with said motor passage downstream of said variable orifice and blocking communication of said first pilot passage with the reservoir; and means connecting said first and second pilot passages with said opposite end of the pressure responsive spool whereby to maintain low pressure of the reservoir at said opposite end when said manual control spool is in its neutral position and to transmit pressure from said motor passage downstream of said variable orifice to said opposite end to assist said biasing means in moving said pressure responsive spool to said variable metering positions when said manual control is in its operating position to maintain a substantially constant pressure differential across said variable orifice.
Claim 14
Dependent Claim
125 words
A control valve as set forth in claim 11, wherein said housing includes a third longitudinal bore intercepting said inlet passage in hydraulically parallel arrangement with said second bore, and another motor passage intercepting said third bore adjacent said inlet passage, said first pilot passage intercepting said second and third bores in series arrangement, said second pilot passage intercepting said second and third bores in parallel arrangement; there being another manual control spool in said third bore for controlling flow from said inlet passage to said another motor passage, said another control spool being operable to block said first pilot passage in a neutral position and to connect said second pilot passage and the inlet passage with said another motor passage in an operating position.
Claim 15
Dependent Claim
47 words
A control valve as set forth in claim 12, wherein is included means in said second pilot passage for preventing fluid flow therethrough between said motor passages while transmitting the higher of the pressures in said motor passages to said opposite end of the pressure responsive spool.
Claim 16
Dependent Claim
97 words
A control valve as set forth in claim 11, wherein said housing includes a second motor port passage intercepting said second bore and communicating with said motor, whereby upon shifting said manual control spool in opposite directions away from neutral said firstmentioned and said second motor passages are respectively connected with said inlet passage, said second pilot passage being arranged to connect said opposite end of the pressure responsive spool only with the one of said first and second motor passages which is communicating with said inlet passage as said control spool is moved away from neutral.
Claim 17
Dependent Claim
64 words
A control valve as set forth in claim 14, wherein said manual control spool is shiftable to a float position interconnecting both said first and second motor port passages with reservoir while blocking flow from said source to said motor, said manual control spool in said float position connecting said first pilot passage with the reservoir and blocking flow through said second pilot passage.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |