EP0594137A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Hydraulic power steering apparatus
Assignee: Toyoda Koki KK
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Filing: 1993-10-19
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Granted: —
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Expires: 2013-10-19
Abstract
Abstract A power steering apparatus having a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir. The control valve has a first control portion for controlling the flow of pressurized fluid from the fluid source to the reservoir, and a second control portion for controlling the flow of pressurized fluid to the power cylinder. The first control portion has two paths connecting the fluid source and the reservoir, each of the paths being formed with at least one variable orifice of a center-open type which opens when the control valve is in a neutral state. The second control portion has two supply paths communicating with the fluid source and a pair of chambers of the power cylinder, each of the supply paths being formed with a variable orifice of a center-close type which closes when the control valve is in the neutral state, and two drain paths communicating with the pair of chambers and the reservoir, each of the drain paths being formed with a variable orifice of a center-open type which opens when the control valve is in the neutral state.
Inventors
- 👤 Kyosuke Haga
- 👤 Mikio Suzuki
- 👤 Yoshiharu Inaguma
- 👤 Kenichi Fukumura
- 👤 Hideya Kato
- 👤 Katsuhisa Mori
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 16:01
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/06; B62D6/00; B62D6/02; B62D5/08; B62D5/083; F; F04; F04B; F04B49/00; F04B49/22; F04B49/225; F04B2205/00; F04B2205/06; F04B2205/08
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
167 words
A power steering apparatus having a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir, wherein said control valve comprises: a first control portion for controlling the flow of pressurized fluid from said fluid source to said reservoir, said first control portion having a path connecting said fluid source and said reservoir, and said path being formed with at least one variable orifice of a center-open type which opens when said control valve is in a neutral state; and a second control portion for controlling the flow of pressurized fluid to said power cylinder, said second control portion having two supply paths communicating with said fluid source and a pair of chambers of said power cylinder, each of said supply paths being formed with a variable orifice of a center-close type which closes when said control valve is in the neutral state.
Claim 2
Dependent Claim
167 words
A power steering apparatus having a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir, wherein said control valve comprises: a first control portion for controlling the flow of pressurized fluid from said fluid source to said reservoir, said first control portion having a path connecting said fluid source and said reservoir, and said path being formed with at least one variable orifice of a center-open type which opens when said control valve is in a neutral state; and a second control portion for controlling the flow of pressurized fluid to said power cylinder, said second control portion having two supply paths communicating with said fluid source and a pair of chambers of said power cylinder, each of said supply paths being formed with a variable orifice of a center-close type which closes when said control valve is in the neutral state.
Claim 3
Dependent Claim
166 words
A power steering apparatus according to Claim 1, wherein said first control portion forms a first fluid bridge circuit having two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice of a center-open type which opens when said control valve is in the neutral state, and said second control portion forms a second fluid bridge circuit having two supply paths communicating with said fluid source and chambers of said power cylinder and two drain paths communicating with the chambers of said power cylinder and said reservoir, each of the supply paths of said second control portion being formed with a variable orifice of a center-close type which closes when said control valve is in the neutral state, and each of the drain paths of said second control portion being formed with a variable orifice of a center-open type which opens when said control valve is in the neutral state.
Claim 4
Dependent Claim
55 words
A power steering apparatus according to Claim 1, further comprising: flow rate control means for reducing the amount of fluid suppled to said control valve when said control valve is in the neutral state and for increasing the amount of the fluid in accordance with an increase in the back pressure of said control valve.
Claim 5
Dependent Claim
199 words
A power steering apparatus according to Claim 3, wherein said first control portion forms a first fluid bridge circuit having two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice of a semi center-open type which opens when said control valve is in the neutral state, and said second control portion forms a second fluid bridge circuit having two supply paths communicating with said fluid source and the chambers of said power cylinder and two drain paths communicating with the chambers of said power cylinder and said reservoir, each of the supply paths of said second control portion being formed with a variable orifice of a center-close type which closes when said control valve is in the neutral state, and each of the drain paths of said second control portion being formed with a variable orifice of a center-open type which opens when said control valve is in the neutral state, and wherein each of said variable orifices of said first control portion starts to close when the variable orifices of said supply paths of said second control portion start to open.
Claim 6
Dependent Claim
113 words
A power steering apparatus according to Claim 3, wherein said flow rate control means comprises: a metering orifice disposed in the middle of a supply passage through which pressurized fluid supplied to said control valve; a bypass valve responsive to a pressure drop across the metering orifice for bypassing part of pressurized fluid output from said fluid source to said reservoir; and load responsive means responsive to the back pressure of said control valve to control said bypass valve so as to increase the amount of fluid bypassed to said reservoir when the back pressure is low and decrease the amount of fluid bypassed to said reservoir when the back pressure becomes high.
Claim 7
Dependent Claim
98 words
A power steering apparatus according to Claim 5, wherein said bypass valve has a spring chamber in which a spring for urging a valve spool of said bypass valve to move in a direction for reducing the amount of bypassed fluid and which is connected to the supply passage at the downstream side of said metering orifice, and said load responsive means composes a load responsive valve disposed between the spring chamber of said bypass valve and said reservoir for fluidly connecting the spring chamber with said reservoir when the back pressure of the control valve is low.
Claim 8
Dependent Claim
32 words
A power steering apparatus according to Claim 6, wherein said load responsive means further comprises an electromagnet valve disposed in a fluid path between the spring chamber and said load responsive valve.
Claim 9
Dependent Claim
61 words
A power steering apparatus according to Claim 1, wherein said fluid source is composed of a pump, and said power steering apparatus further comprises: a motor for driving said pump; detection means for detecting steering operation of the steering wheel; and control means for controlling the rotational speed of said motor in response to a signal output from said detection means.
Claim 10
Dependent Claim
46 words
A power steering apparatus according to Claim 8, wherein said apparatus further comprises a speed sensor for detecting the speed of a vehicle, and said control means controls said motor such that the rotational speed of said motor decreases as the speed of the vehicle increases.
Claim 11
Dependent Claim
309 words
A power steering apparatus having a fluid source for delivering pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir, wherein said control valve comprises: a first control portion which forms a first fluid bridge circuit having two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice; a second control portion which forms a second fluid bridge circuit having two supply paths communicating with said fluid source and chambers of said power cylinder and two drain paths communicating with the chambers of said power cylinder and said reservoir, each of said four paths being formed with a variable orifice; and flow rate control means for reducing the amount of fluid suppled to said control valve when said control valve is in the neutral state and for increasing the amount of the fluid in accordance with increase of the back pressure of said control valve, wherein each of the variable orifices of said first control portion is composed of a semi center-open type orifice which opens when said control valve is in the neutral state, each of the variable orifices disposed in the supply paths of said second control portion is composed of a center-close type orifice which closes when said control valve is in the neutral state, and each of the variable orifices disposed in the drain paths of said second control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state, and wherein each of said variable orifices of said first control portion starts to close when the variable orifices of said supply paths of said second control portion start to open.
Claim 12
Dependent Claim
309 words
A power steering apparatus having a fluid source for delivering pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir, wherein said control valve comprises: a first control portion which forms a first fluid bridge circuit having two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice; a second control portion which forms a second fluid bridge circuit having two supply paths communicating with said fluid source and chambers of said power cylinder and two drain paths communicating with the chambers of said power cylinder and said reservoir, each of said four paths being formed with a variable orifice; and flow rate control means for reducing the amount of fluid suppled to said control valve when said control valve is in the neutral state and for increasing the amount of the fluid in accordance with increase of the back pressure of said control valve, wherein each of the variable orifices of said first control portion is composed of a semi center-open type orifice which opens when said control valve is in the neutral state, each of the variable orifices disposed in the supply paths of said second control portion is composed of a center-close type orifice which closes when said control valve is in the neutral state, and each of the variable orifices disposed in the drain paths of said second control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state, and wherein each of said variable orifices of said first control portion starts to close when the variable orifices of said supply paths of said second control portion start to open.
Claim 13
Dependent Claim
258 words
A power steering apparatus having a pump driven by a motor, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the pump, and a reservoir, wherein said control valve comprises: a first control portion which forms a first fluid bridge circuit having two supply paths communicating with said pump and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice; a second control portion which forms a second fluid bridge circuit having two supply paths communicating with said pump and chambers of said power cylinder and two drain paths communicating with the chambers of said cylinder and said reservoir, each of said four paths being formed with a variable orifice; detection means for detecting steering operation of the steering wheel; and control means for controlling the rotational speed of said motor in response to a signal output from said detection means, wherein each of the variable orifices of said first control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state, each of the variable orifices disposed in the supply paths of said second control portion is composed of a center-close type orifice which closes when said control valve is in the neutral state, and each of the variable orifices disposed in the drain paths of said second control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state.
Claim 14
Dependent Claim
258 words
A power steering apparatus having a pump driven by a motor, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the pump, and a reservoir, wherein said control valve comprises: a first control portion which forms a first fluid bridge circuit having two supply paths communicating with said pump and two drain paths communicating with said reservoir, each of said four paths being formed with a variable orifice; a second control portion which forms a second fluid bridge circuit having two supply paths communicating with said pump and chambers of said power cylinder and two drain paths communicating with the chambers of said cylinder and said reservoir, each of said four paths being formed with a variable orifice; detection means for detecting steering operation of the steering wheel; and control means for controlling the rotational speed of said motor in response to a signal output from said detection means, wherein each of the variable orifices of said first control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state, each of the variable orifices disposed in the supply paths of said second control portion is composed of a center-close type orifice which closes when said control valve is in the neutral state, and each of the variable orifices disposed in the drain paths of said second control portion is composed of a center-open type orifice which opens when said control valve is in the neutral state.
References Cited (Backward Citations)
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