Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Hitachi Astemo Ltd.

Hitachi Automotive Systems Steering, Ltd.

Jun Soeda

Tadaharu Yokota

Yukio Uchida

Norikatsu Hoshina

Michiya Hiramoto

Satoshi Nonaka

Takao Muto

The present invention is to provide a vehicle-mounted apparatus having a biasing structure using a coil spring capable of reducing a lateral force of a coil spring that is applied to a biasing target member. When N1, n1, N0, and n0 represent the number of effective turns when the relief valve springis set in a valve holeof a spoolin a compressed state, a value of an integer of N1, the number of effective turns when a length of the relief valve springis a natural length, and a value of an integer of N0, respectively, the springsatisfies an equation 1: 0&#x2264;N1&#x2212;n1&#x2264;0.25 or an equation 2: 0.75&#x2264;N1&#x2212;n1&#x3c;1.

Vehicle-mounted apparatus having biasing structure using coil spring

Provided is a variable displacement vane pump which is capable of reducing fluctuation in discharge rate. In the variable displacement vane pump, a first straightening vaneclosest to one end-side openingof a discharge passageamong a plurality of straightening vanesandarranged within the discharge pressure chamberis located so as not to face a communication holeof a pressure plate

Variable displacement vane pump

A pump deviceincludes a relief valvehaving a balland a valve seat. The valve seathas a ring-shaped seat surfacehaving a wide portionand a narrow portionon which the ballis seated. Upon valve opening, the ballis pressed in a valve opening direction by a pressing force Faccording to a pressure P of working fluid while being pressed against the wide portion. The ballrolls on the seat surfaceupon the valve opening while continuing or keeping contact with the wide portion. At this time, the ballis stably held with the ballcontacting the wide portionof the seat surface. Noise of the relief valvecaused by vibration of the ballis therefore suppressed.

Pump device

A variable displacement vane pump including a relief valve which includes a valve bore, a spherical valve element in the valve bore, a valve seat fixed onto one axial side of the valve bore and having a through hole and an annular seat surface on which the valve element is seated when the relief valve is in a closed position, a coil spring disposed on the other axial side of the valve bore, and a valve element retainer disposed between the valve element and the coil spring, wherein the seat surface is configured such that when the relief valve is in the closed position, a center of the valve element is located offset from a central axis of one winding seating portion of the coil spring which is disposed on an opposite side of the seat surface, in a radial direction of the valve bore.

A variable displacement pump includes: a pump body; a rotor; a cam ring; inlet and outlet ports; first and second fluid pressure chambers; a metering orifice provided in a discharge passage connected with the outlet port; a pressure regulating section arranged to regulate the pressure introduced into the first or second fluid pressure chamber, and including a high pressure chamber, a middle pressure chamber, and a low pressure chamber; a relief valve; a pilot orifice provided in a passage connecting the metering orifice and the middle pressure chamber, and having a circular section with a diameter of a mm; and a damper orifice provided in a passage connecting the outlet port and the high pressure chamber, and having a circular section with a diameter of b mm. The pilot orifice and the damper orifice satisfy the following relationships: a+2b&#x2212;2.1&#x2267;0, &#x2212;4a+b&#x2212;16.3&#x2266;0, and a&#x2266;1.8.

Variable displacement pump

A variable displacement vane pump that assuredly suppresses seizing of mutually contacting surfaces of a pressure plate and a rotor where the pressure plate is formed, at one side surface thereof that slidably contacts the rotor, with an annular lubricating groove. The lubricating groove is on a seal surface of the side surface at a position between arcuate back pressure grooves formed on the seal surface and a through opening which is formed in a center part of the pressure plate to receive the drive shaft. A radial width of the lubricating groove is set to a range from 10% to 25% of a radial width of the seal surface, and a distance from a center of the radial width of the lubricating groove to an inner cylindrical surface of the through opening is set to a range from 24% to 70% of the radial width of the seal surface.

A variable displacement vane pump includes a rotor, a cam ring; and a pump casing including first and second side walls disposed on both sides of the cam ring, and a circumferential wall surrounding the cam ring and defining first and second pressure chambers. A pressure introduction groove is formed in a sliding contact surface between the cam ring and one of the first and second side walls, and arranged so that a pressure lower than an outlet pressure is introduced.

A power steering system includes first and second communication passages for providing communication between a first oil passage and a second oil passage, a third communication passage for providing communication between the first and second communication passages, a directional control valve disposed in the third communication passage, a first check valve disposed in the first communication passage for allowing flow from the first oil passage to a first connection portion only, a second check valve disposed in the first communication passage for allowing flow from second oil passage to the first connection portion only, a third check valve disposed in the second communication passage for allowing flow from a second connection portion to the first oil passage only, and a fourth check valve disposed in the second communication passage for allowing flow from the second connection portion to the second oil passage only.

Power steering system

A power steering apparatus includes a hydraulic power cylinder, a reversible pump including a first outlet connected with a first pressure chamber of the power cylinder through a first fluid passage, and a second outlet connected with a second pressure chamber of the power cylinder through a second fluid passage, and a motor for driving the pump. A controller controls the motor in accordance with a sensed steering force. There is further provided a connection passage connecting the first and second fluid passages together, and a closing valve disposed in the connection passage. The controller sends a first current to a coil of the valve to close the connection passage by moving an armature, to send a second current lower than the first current to the coil after the connection passage is closed, and to deenergize the coil to open the connection passage.

Power steering apparatus

In a power steering system employing a power cylinder for steering assistance, hydraulic pressure is supplied through a pair of fluid lines to respective hydraulic chambers of the power cylinder. Check valves are provided to charge a hydraulic pressure in a communicating circuit intercommunicating the two fluid lines. Also provided is a solenoid-actuated directional control valve for relieving the hydraulic pressure charged in presence of a power steering system failure. An opening of the directional control valve varies depending on a solenoid attracting force and a pressure differential between the hydraulic pressure in the communicating circuit and hydraulic pressure in a reservoir. A relatively low exciting current is applied to the solenoid when the hydraulic pressure charged exceeds a predetermined pressure value. A relatively high exciting current is applied to the solenoid when the hydraulic pressure charged is less than or equal to the predetermined pressure value.

In a hydraulic power steering system employing a power cylinder accommodating therein a piston connected to a steering mechanism for steering assistance, and having first and second hydraulic chambers defined on both sides of the piston, hydraulic pressure is supplied through first and second fluid lines to the respective hydraulic chambers. A communicating circuit is provided to intercommunicate the first and second fluid lines therevia. A directional control valve, disposed in the communicating circuit, has a poppet valve mechanism, which is switched to a valve-open position in presence of a hydraulic power steering system failure, to intercommunicate the first and second fluid lines with the poppet valve mechanism opened.

Growing community of inventors

Fujisawa, Japan

Jun Soeda