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EP0653342A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Hydraulic power steering apparatus

Assignee: Toyoda Koki KK
•
Filing: 1994-11-11
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Granted: —
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Expires: 2014-11-11
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Abstract

Abstract A power steering apparatus comprises a fluid source (10) for discharging pressurized fluid, a power cylinder (12), a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid, and a reservoir (11). 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 four paths communicating with the fluid source and the reservoir, and each of the four paths is formed with a variable orifice (V1-V4) of open-center type which is open when the control valve is in a neutral state. The second control portion has two supply paths communicating with the fluid source and the chambers of the power cylinder, each of the two supply paths being formed with a variable orifice (V5,V6) of semi-open-center type which is open when the control valve is in the neutral state, and two drain paths communicating with the chambers of the power cylinder and the reservoir, each of the two drain paths being formed with a variable orifice (V7,V8) of closed-center type which is closed when the control valve is in the neutral state.

Inventors

  • 👤 Kyosuke Haga
  • 👤 Mikio Suzuki
  • 👤 Katsuhisa Mori

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-08 16:07
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/06; B62D5/08; B62D5/083

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 218 words
A power steering apparatus having a fluid source for supplying pressurized fluid, a power cylinder, a control valve responsive to the operation of a steering wheel for supplying said power cylinder with pressurized fluid from said fluid source, and a reservoir, said control valve comprising: a first control portion for controlling the flow of pressurized fluid from said fluid source to said reservoir, said first control portion having at least one path connecting said fluid source and said reservoir, and said path being formed with at least one variable orifice of 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 from said fluid source to said power cylinder, said second control portion having two supply paths making said fluid source communicate respectively with a pair of fluid chambers of said power cylinder and two drain paths respectively making the chambers of said power cylinder communicate with said reservoir, wherein each of said two supply paths is formed with a variable orifice of center-open type which opens when said control valve is in the neutral state, while each of said two drain paths is formed with a variable orifice of center-closed type which closes when said control valve is in the neutral state.
Claim 2
Dependent Claim 41 words
A power steering apparatus according to claim 1, wherein each of said fluid chambers of said power cylinder communicates with each other through said two supply paths of said second control portion when said control valve is in the neutral state.
Claim 3
Dependent Claim 48 words
A power steering apparatus according to claim 1, wherein each of said variable orifices formed in said two supply paths of said second control portion is of semi-center-open type whose opening area is smaller than that of center-open type when said control valve is in the neutral state.
Claim 4
Dependent Claim 59 words
A power steering apparatus according to Claim 1, wherein said first control portion forms two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said paths of said first control portion being formed with a variable orifice of center-open type which opens when said control valve is in the neutral state.
Claim 5
Dependent Claim 50 words
A power steering apparatus according to Claim 1, further comprising: flow rate control means for reducing pressurized fluid supplied to said control valve when said control valve is in the neutral state and for increasing pressurized fluid in accordance with an increase in the back pressure of said control valve.
Claim 6
Dependent Claim 59 words
A power steering apparatus according to Claim 5, wherein said first control portion forms two supply paths communicating with said fluid source and two drain paths communicating with said reservoir, each of said paths of said first control portion being formed with a variable orifice of center-open type which opens when said control valve is in the neutral state.

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