Abstract: A power assisted steering system of the type which includes a hydraulic reaction mechanism for controlling the hydraulic power assist in accordance with an increase or decrease of the vehicle speed. The system includes primary and secondary hydraulic pumps, the primary pump having the function of applying hydraulic pressure to the power cylinder and the secondary pump having the function of applying hydraulic pressure to the reaction mechanism in proportion to the vehicle speed. The secondary pump is unitedly assembled with the primary pump to be driven by the prime mover, and comprises a first control valve for controlling the quantity of fluid applied to the reaction mechanism for the secondary pump in a constant amount, and a second control valve for controlling the pressure of fluid controlled by the first control valve in accordance with the vehicle speed.

Abstract: A power steering, comprising: a pump driven from an engine; a flow control valve for regularizing the discharge rate of the pump varying in response to the rotational speed of the engine; a power cylinder; a distribution control valve for distributing a regularized fluid pressure from the flow control valve to opposite fluid chambers of the power cylinder; a sector gear meshed with a rack formed on the piston of the power cylinder and rotatable by operation of the power cylinder; a sector shaft having the sector gear formed integrally therewith and displaceable in the axial direction for adjusting the preload on the meshed rack and sector gear; a preload control cylinder for axially displacing the sector shaft, the preload control cylinder including a piston connected to the sector shaft and having different pressure receiving areas on the axially opposite ends thereof; a first fluid passage for conducting part of the pressurized fluid being sent from the pump to said flow control valve, to one of fluid chamb

Abstract: A power steering system which includes an engine-driven pump, a fluid motor for supplementing manual steering torque, a fluid control valve for distributing fluid to the fluid motor, and a reaction device for applying hydraulic reaction or feeling to a steering wheel. A first flow control valve is utilized to deliver first fluid flow to a fluid control valve from the pump and to lead excess flow to a bypass passage. A second flow control valve is connected between the bypass passage and the reaction device to deliver second fluid flow to the reaction device and to lead excess flow to a reservoir. A magnetic pressure control valve is connected to the reaction device to control fluid pressure applied thereto in accordance with a predetermined vehicle operating condition, such as vehicle speed.

Abstract: A vane pump for use in a power steering device comprising a pump housing receiving a cam ring therein. A pair of side plates are disposed at opposite side of the cam ring in contact relationship therewith. A pump rotor rotatable integrally with a drive shaft is received in an internal cam bore of the cam ring. An end cover is secured to the pump housing in contact relationship with one of the side plates to cover an open end of the pump housing. A first positioning pin is fitted at one end thereof into an inner end wall of the pump housing for positioning the first and second side plates in a circumferential direction. A second positioning pin is fitted at one end thereof into one of the first and second side plates for positioning the cam ring in the circumferential direction.

Abstract: Method for producing a pressure plate used in a hydraulic pump by connecting first and second plate sections together include the steps of pressing metal powders to individually form the first and second plate sections and a ring member into predetermined configurations, placing the first plate section properly on the second plate section while the ring member is inserted in a bore formed in the first plate section, placing brazing metal along the upper side diameter of the bore, and heating the first and second plate sections and the ring member so as to connect the first and second plate sections and the ring member together by the brazing metal and simultaneously sintering the same.

Abstract: A hydraulic fluid discharged from a pump is delivered to a power steering device from a supply passage through a restricted passage and a throttled passage so that as the flow through the supply passage increases in response to an increase in the number of revolutions of the pump, the flow path resistance presented by the restricted passage increases the pressure prevailing in the supply passage to cause a control spool to control the flow area of the throttled passage, thus decreasing the flow delivered to the power steering device. In this manner, a constant and invariable flow decrease characteristic can be maintained despite a loading pressure upon the power steering device, thus enhancing the stability under high speed running conditions. A mechanism to provide a variable control of the flow delivered to the power steering device is provided in a union which is fixedly mounted in one end of a bore in a pump housing.

Abstract: A vane type hydraulic pump for use in a power steering apparatus comprising a pump housing receiving therein a non-rotatable cam ring and non-rotatable but axially slidable pressure plate and subplate. A pump rotor rotatable integrally with a drive shaft is received in an internal cam bore of the cam ring and, when rotated, delivers pressurized fluid to a discharge port connected to the power steering apparatus. The pressure plate and subplate define at a contact portion therebetween a radial low pressure passage, which is fluidically communicated with an axial low pressure hole receiving fluid from a pump reservoir and bypassed fluid from a flow volume control valve. The radially outer portions of the low pressure passage are gradually curved in a direction of rotation of the pump rotor.