# US 9,038,763 B2 · Hydraulic power steering system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,763 B2 - Document ID: US9038763B2 - Status: Granted - Kind: B2 - Application number: 13/273,866 - Filed: 2011-10-14 - Published: 2012-04-26 - Granted: 2015-05-26 - Earliest claimed: 2010-10-22 - Assignees: Jtekt Corporation - Applicants: Ryouichi Kubo; Yasuhiro Tomagou; Akihiko Shiina; Masahiko Sakamaki; Tetsuya Ozaki - Inventors: Ryouichi Kubo; Yasuhiro Tomagou; Akihiko Shiina; Masahiko Sakamaki; Tetsuya Ozaki - Web page: https://patentgrep.com/patent/US9038763B2 ## CPC - B62D 5/065: characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist - B62D 5/064: {Pump driven independently from vehicle engine, e.g. electric driven pump (B62D5/065 takes precedence)} - B62D 5/09: characterised by means for actuating valves - B62D 15/027: {Parking aids, e.g. instruction means} - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) ## Abstract A hydraulic power steering system includes: a hydraulic cylinder in which an interior is partitioned into first and second hydraulic chambers by a piston on a steered shaft; a variable displacement electric pump that supplies hydraulic fluid to the hydraulic cylinder; a selector valve selectively set in a mode in which the hydraulic fluid is supplied to the first hydraulic chamber and drained from the second hydraulic chamber or in a mode in which the hydraulic fluid is supplied to the second hydraulic chamber and drained from the first hydraulic chamber; a detector that detects torque, steering angle, and/or vehicle speed; and a controller. ## Claims ### Claim 1 A hydraulic power steering system comprising: a hydraulic cylinder in which an interior is partitioned into a first hydraulic chamber and a second hydraulic chamber by a piston provided on a steered shaft; and an electric pump that supplies a hydraulic fluid to the hydraulic cylinder, and the hydraulic power steering system assisting a steering operation for steering a vehicle by moving the steered shaft together with the piston using a force produced due to a difference between a hydraulic pressure in the first hydraulic chamber and a hydraulic pressure in the second hydraulic chamber; a selector valve that is selectively set in an operation mode in which the hydraulic fluid is supplied to the first hydraulic chamber while the hydraulic fluid is drained from the second hydraulic chamber or in an operation mode in which the hydraulic fluid is supplied to the second hydraulic chamber while the hydraulic fluid is drained from the first hydraulic chamber; a detector that detects an operation state of the vehicle; and a controller that sets, based on the operation state detected by the detector, a fluid supply-drain mode in which the hydraulic fluid is supplied to and drained from the hydraulic cylinder, and controls the operation mode of the selector valve and an amount of hydraulic fluid that is supplied from the electric pump based on the set fluid supply-drain mode, wherein the controller controls, when a steering wheel is turned back toward a neutral steering position, the operation mode of the selector valve such that a drain of the hydraulic fluid from the hydraulic chamber of which a capacity decreases, from among the first and second hydraulic chambers, is suppressed. ### Claim 2 (depends on 1) The hydraulic power steering system according to claim 1, wherein the detector detects, as the operation state of the vehicle, at least one of a steering torque, a steering angle, and a vehicle speed. ### Claim 3 (depends on 2) The hydraulic power steering system according to claim 2, wherein the controller obtains information on a positional relation between a target parking spot and a present position of the vehicle, and controls, based on the obtained information and the detected operation state of the vehicle, the selector valve and the electric pump so as to bring the vehicle into the target parking spot. ### Claim 4 (depends on 3) The hydraulic power steering system according to claim 3, wherein the controller obtains information on a position of the vehicle relative to a travel lane on a road surface, and controls, based on the obtained information and the detected operation state of the vehicle, the selector valve and the electric pump so as to keep the vehicle in the travel lane. ### Claim 5 (depends on 3) The hydraulic power steering system according to claim 3, further comprising: a drain valve that adjusts an amount of hydraulic fluid discharged from the first hydraulic chamber and an amount of the hydraulic fluid discharged from the second hydraulic chamber, wherein the selector valve includes: a housing that has a supply port from which the hydraulic fluid is supplied, a first port connected to the first hydraulic chamber, and a second port connected to the second hydraulic chamber; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the supply port, the first port, and the second port, between a first mode in which the supply port and the first port are in communication with each other and a second mode in which the supply port and the second port are in communication with each other; and a drive mechanism causes a reciprocation motion of the valve member, wherein the drain valve includes: a housing that has a first port to which the hydraulic fluid discharged from the first hydraulic chamber is supplied, a second port to which the hydraulic fluid discharged from the second hydraulic chamber is supplied, and a drain port from which the hydraulic fluid is drained; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the first port, the second port, and the drain port, between a first mode in which the first port and the drain port are in communication with each other and a second mode in which the second port and the drain port are in communication with each other; and a drive mechanism that causes a reciprocating motion of the valve member, and wherein the controller selectively establishes a mode combination state where the selector valve is in the first mode and the drain valve is in the second mode or a mode combination state where the selector valve is in the second mode and the drain valve is in the first mode, by adjusting a travel amount of the valve member of the selector valve using the drive mechanism of the selector valve and a travel amount of the valve member of the drain valve using the drive mechanism of the drain valve, based on the set fluid supply-drain manner. ### Claim 6 (depends on 2) The hydraulic power steering system according to claim 2, wherein the controller obtains information on a position of the vehicle relative to a travel lane on a road surface, and controls, based on the obtained information and the detected operation state of the vehicle, the selector valve and the electric pump so as to keep the vehicle in the travel lane. ### Claim 7 (depends on 2) The hydraulic power steering system according to claim 2, further comprising: a drain valve that adjusts an amount of hydraulic fluid discharged from the first hydraulic chamber and an amount of the hydraulic fluid discharged from the second hydraulic chamber, wherein the selector valve includes: a housing that has a supply port from which the hydraulic fluid is supplied, a first port connected to the first hydraulic chamber, and a second port connected to the second hydraulic chamber; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the supply port, the first port, and the second port, between a first mode in which the supply port and the first port are in communication with each other and a second mode in which the supply port and the second port are in communication with each other; and a drive mechanism causes a reciprocation motion of the valve member, wherein the drain valve includes: a housing that has a first port to which the hydraulic fluid discharged from the first hydraulic chamber is supplied, a second port to which the hydraulic fluid discharged from the second hydraulic chamber is supplied, and a drain port from which the hydraulic fluid is drained; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the first port, the second port, and the drain port, between a first mode in which the first port and the drain port are in communication with each other and a second mode in which the second port and the drain port are in communication with each other; and a drive mechanism that causes a reciprocating motion of the valve member, and wherein the controller selectively establishes a mode combination state where the selector valve is in the first mode and the drain valve is in the second mode or a mode combination state where the selector valve is in the second mode and the drain valve is in the first mode, by adjusting a travel amount of the valve member of the selector valve using the drive mechanism of the selector valve and a travel amount of the valve member of the drain valve using the drive mechanism of the drain valve, based on the set fluid supply-drain manner. ### Claim 8 (depends on 6) The hydraulic power steering system according to claim 6, further comprising: a drain valve that adjusts an amount of hydraulic fluid discharged from the first hydraulic chamber and an amount of the hydraulic fluid discharged from the second hydraulic chamber, wherein the selector valve includes: a housing that has a supply port from which the hydraulic fluid is supplied, a first port connected to the first hydraulic chamber, and a second port connected to the second hydraulic chamber; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the supply port, the first port, and the second port, between a first mode in which the supply port and the first port are in communication with each other and a second mode in which the supply port and the second port are in communication with each other; and a drive mechanism causes a reciprocation motion of the valve member, wherein the drain valve includes: a housing that has a first port to which the hydraulic fluid discharged from the first hydraulic chamber is supplied, a second port to which the hydraulic fluid discharged from the second hydraulic chamber is supplied, and a drain port from which the hydraulic fluid is drained; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the first port, the second port, and the drain port, between a first mode in which the first port and the drain port are in communication with each other and a second mode in which the second port and the drain port are in communication with each other; and a drive mechanism that causes a reciprocating motion of the valve member, and wherein the controller selectively establishes a mode combination state where the selector valve is in the first mode and the drain valve is in the second mode or a mode combination state where the selector valve is in the second mode and the drain valve is in the first mode, by adjusting a travel amount of the valve member of the selector valve using the drive mechanism of the selector valve and a travel amount of the valve member of the drain valve using the drive mechanism of the drain valve, based on the set fluid supply-drain manner. ### Claim 9 (depends on 1) The hydraulic power steering system according to claim 1, further comprising: a drain valve that adjusts an amount of hydraulic fluid discharged from the first hydraulic chamber and an amount of the hydraulic fluid discharged from the second hydraulic chamber, wherein the selector valve includes: a housing that has a supply port from which the hydraulic fluid is supplied, a first port connected to the first hydraulic chamber, and a second port connected to the second hydraulic chamber; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the supply port, the first port, and the second port, between a first mode in which the supply port and the first port are in communication with each other and a second mode in which the supply port and the second port are in communication with each other; and a drive mechanism causes a reciprocation motion of the valve member, wherein the drain valve includes: a housing that has a first port to which the hydraulic fluid discharged from the first hydraulic chamber is supplied, a second port to which the hydraulic fluid discharged from the second hydraulic chamber is supplied, and a drain port from which the hydraulic fluid is drained; a valve member that is disposed in the housing so as to be allowed to reciprocate in the housing and that is used to switch a mode of communications among the first port, the second port, and the drain port, between a first mode in which the first port and the drain port are in communication with each other and a second mode in which the second port and the drain port are in communication with each other; and a drive mechanism that causes a reciprocating motion of the valve member, and wherein the controller selectively establishes a mode combination state where the selector valve is in the first mode and the drain valve is in the second mode or a mode combination state where the selector valve is in the second mode and the drain valve is in the first mode, by adjusting a travel amount of the valve member of the selector valve using the drive mechanism of the selector valve and a travel amount of the valve member of the drain valve using the drive mechanism of the drain valve, based on the set fluid supply-drain manner. ### Claim 10 (depends on 9) The hydraulic power steering system according to claim 9, wherein the valve member of the drain valve has a communication portion via which the first port and the drain port are in communication with each other when the mode of communications among the first port, the second port, and the drain port is the second mode and another communication portion via which the second port and the drain port are in communication with each other when the mode of communications among the first port, the second port, and the drain port is the first mode, and a flow passage area of each of the commutation portions is set such that a flowrate at which the hydraulic fluid flows through the communication portion is lower than a flowrate at which the hydraulic fluid is drained via the first port and the drain port when the mode of communications among the first port, the second port, and the drain port is the first mode and a flowrate at which the hydraulic fluid is drained via the second port and the drain port when the mode of communications among the first port, the second port, and the drain port is the second mode. ### Claim 11 (depends on 10) The hydraulic power steering system according to claim 10, wherein the communication portions are annular grooves formed in an outer face of the valve member. ### Claim 12 (depends on 10) The hydraulic power steering system according to claim 10, wherein the communication portions are tapered portions that are formed in the valve member of the drain valve and that change, respectively, a flow passage area of the first port and a flow passage area of the second port based on a position of the valve element, to adjust an amount of the hydraulic fluid that is discharged from one of the first hydraulic chamber and the second hydraulic chamber when the steering wheel is turned back toward the neutral steering position.