Fluid control valve for a hydraulic system operating with variable viscosity, contaminated, fluid
First Claim
1. A hydraulic system comprising, a pressure actuated hydraulic device, a source of pressurized hydraulic fluid, a low pressure reservoir, a source of control signals, and a clevis-type pressure control valve, with said clevis-type pressure control valve including:
- means for receiving a flow of pressurized hydraulic fluid from said source of pressurized hydraulic fluid and delivering said flow to said low pressure reservoir; and
means for converting a portion of said flow into a predetermined control pressure corresponding to control signals received from a source of control signals, and applying said control pressure to said pressure actuated hydraulic device;
with said means for converting including a clevis-type fluid pressure control stage.
1 Assignment
0 Petitions
Accused Products
Abstract
Problems such as slow frequency response and low reliability when operating with contaminated fluids of variable viscosity are alleviated in a low pressure hydraulic system (10) which utilizes a single stage, electro-hydraulic, clevis-type pressure control valve (40). The valve (40)includes a control piston (106) referenced to a control pressure within a control pressure cavity (60) to provide a feedback of control pressure which converts the valve (40) from an integral to a proportional control device, thereby enhancing stability of the hydraulic system (10). Compensation for changes in fluid viscosity, as a result of changes in fluid temperature, is provided by fabricating a bifurcated portion (98) and/or a metering bridge portion (62) of the valve (10) from materials having dissimilar coefficients of thermal expansion. Exemplary embodiments of a hydraulic system (10) suitable for use in either vehicular or stationary applications involving pressure actuated devices, such as a clutch (16), automatic transmissions or anti-lock brakes, are provided.
29 Citations
40 Claims
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1. A hydraulic system comprising, a pressure actuated hydraulic device, a source of pressurized hydraulic fluid, a low pressure reservoir, a source of control signals, and a clevis-type pressure control valve, with said clevis-type pressure control valve including:
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means for receiving a flow of pressurized hydraulic fluid from said source of pressurized hydraulic fluid and delivering said flow to said low pressure reservoir; and means for converting a portion of said flow into a predetermined control pressure corresponding to control signals received from a source of control signals, and applying said control pressure to said pressure actuated hydraulic device;
with said means for converting including a clevis-type fluid pressure control stage. - View Dependent Claims (2, 3, 4)
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5. A hydraulic system comprising, a pressure actuated hydraulic device, a source of pressurized hydraulic fluid, a low pressure reservoir, a source of control signals and a pressure control valve, with said pressure control valve including:
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means for receiving a flow of pressurized hydraulic fluid from said source of pressurized hydraulic fluid and delivering said flow to said low pressure reservoir; and means for converting a portion of said flow into a predetermined control pressure corresponding to control signals received from a source of control signals, and applying said control pressure to said pressure actuated hydraulic device; said means for converting including; a single, clevis-type, fluid pressure control stage; and feedback means operably connected to said clevis-type control stage for controlling said single, clevis-type fluid pressure control stage in response to said control pressure. - View Dependent Claims (6, 7)
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8. A pressure control valve, including:
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means for receiving a flow of pressurized hydraulic fluid from a source of pressurized hydraulic fluid and delivering said flow to a low pressure reservoir; and means for converting a portion of said flow into a predetermined control pressure corresponding to control signals received from a source of control signals, said means for converting including a single, clevis-type, fluid pressure control stage having feedback of said control pressure. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. In a fluid control system including a source of pressurized fluid, a low pressure reservoir, a source of control signals, and a pressure actuated device, a pressure control valve comprising:
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a body member defining a fluid inlet passage, a fluid outlet passage, a control pressure passage and a control pressure cavity in fluid communication with said inlet, outlet and control pressure passages; said inlet passage having an inlet port connected to said source of pressurized fluid to receive pressurized fluid therefrom, said outlet passage having an outlet port connected to said low pressure reservoir for returning fluid thereto, and said control pressure cavity having a control port connected to said pressure actuated device for communicating control pressure signals thereto; a portion of said body member further defining a pair of substantially flat, opposed, transversely spaced surfaces exposed to said control pressure cavity, with said pair of surfaces including therein a pair of oppositely facing metering orifices opening into said control pressure cavity to provide fluid communication between said control pressure cavity and said fluid inlet passage such that said pressurized fluid may enter the control pressure cavity through said metering orifices and exit said cavity through said outlet passage, thereby creating a flow of pressurized fluid through said control pressure cavity; a movable metering member mounted within said control pressure cavity of said body member and having a bifurcated portion thereof straddling said portion of said body defining said spaced surfaces, with said bifurcated portion being configured to at least partially overlap said metering orifices when said bifurcated portion is moved in a generally lateral direction along said spaced surfaces; said partial overlapping of said metering orifices by said bifurcated portion thereby creating a pressure drop in said flow of pressurized fluid entering the control pressure cavity from the metering orifices such that fluid pressure within the control pressure cavity may be selectively controlled by varying said overlapping; and actuation means for moving said bifurcated portion of said metering member generally laterally along said spaced surfaces and across said metering orifices to selectively control said overlapping in response to control signals received from said source of control signals, said actuation means including pressure feedback means operatively connected between said control pressure cavity and said movable metering member for urging said bifurcated portion to move laterally along said spaced surfaces and across said metering orifices in response to pressure of the fluid within the control pressure cavity; and said pressure control valve thereby converting said control signals received from said source of control signals into pressure control signals applied to said pressure actuated device. - View Dependent Claims (17, 18)
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19. A pressure control valve, including:
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means for receiving a flow of pressurized hydraulic fluid from a source of pressurized hydraulic fluid and delivering said flow to a low pressure reservoir; and means for converting a portion of said flow into a predetermined control pressure corresponding to control signals received from a source of control signals; said means for converting including; a single, clevis-type, fluid pressure control stage; and viscosity compensation means operably connected to said clevis-type control stage for controlling said single, clevis-type fluid pressure control stage in response to changes in temperature of said pressurized hydraulic fluid. - View Dependent Claims (20, 21, 22, 23)
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24. A fluid control valve comprising:
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a body member defining a fluid inlet passage having an inlet port for receiving pressurized fluid from a source of pressurized fluid, a fluid outlet passage having an outlet port for delivering said pressurized fluid to a low pressure reservoir, a control pressure passage having a control pressure port for communicating a control pressure to a pressure sensitive device and a control pressure cavity in fluid communication with said inlet, outlet and control pressure passages; a portion of said body member further defining a pair of substantially flat, opposed, transversely spaced surfaces exposed to said control pressure cavity, with said pair of surfaces including therein a pair of oppositely facing metering orifices opening into said control pressure cavity to provide fluid communication between said control pressure cavity and said fluid inlet passage; a movable metering member mounted within said control pressure cavity of said body member and having a bifurcated portion thereof straddling said portion of said body defining said spaced surfaces, with said bifurcated portion being configured to at least partially overlap said metering orifices when said bifurcated portion is moved in a generally lateral direction along said spaced surfaces, to thereby create a variable pressure drop in a flow of fluid entering the control pressure cavity from the metering orifices; and actuation means for moving said bifurcated portion of said metering member generally laterally along said spaced surfaces and across said metering orifices in response to control signals, said actuation means including pressure feedback means operatively connected between said control pressure cavity and said movable metering member for urging said bifurcated portion to move laterally along said spaced surfaces and across said metering orifices in response to pressure of the fluid within the control pressure cavity. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification