Trw Limited

Borg-warner Automotive Electronic & Mechanical Systems Corporation

Richard W Dymond

Clarence D Fox, Deceased

Rosamond L Fox, Executrix

A power steering control valve including relatively rotatable inner and outer valve members. A power steering resistance control system resists relative rotation between the inner and outer valve members with a force which varies as a function of variations in vehicle speed and steering demand. The power steering resistance control system includes a force transmitting member which is disposed adjacent to one end of an outer valve member. A spring force is applied against the force transmitting member urging it in a first direction along the axis of rotation of the valve member. Fluid pressure is applied against the force transmitting member to urge it in the first direction. In a first embodiment, a speed responsive valve is operable to vary the fluid pressure applied against the force transmitting member as a function of variations in vehicle speed. A hydraulic pressure responsive valve is operable to vary the fluid pressure applied against the force transmitting member as a function of steering demand. In a second embodiment, only a hydraulic pressure responsive valve controls the pressure applied against the force transmitting member.

Power steering system

A power steering control valve including relatively rotatable inner and outer valve members. A power steering resistance control system resists relative rotation between the inner and outer valve members with a force which varies as a function of variations in vehicle speed and steering demand. The power steering resistance control system includes a force transmitting member which is disposed adjacent to one end of the outer valve member. A spring force is applied against the force transmitting member urging it in a first direction along the axis of rotation of the valve members. Fluid pressure is applied against the force transmitting member to urge it in the first direction. A valve is operable to vary the fluid pressure applied against the force transmitting member. A solenoid valve controls the position of the valve as a function of vehicle speed and steering demand.

Power steering system with speed responsive force transmitting control

A power steering control valve including relatively rotatable inner and outer valve members. A power steering resistance control system resists relative rotation between the inner and outer valve members with a force which varies as a function of variations in vehicle speed. The power steering resistance control system includes a force transmitting member which is disposed adjacent to one end of an outer valve member. A spring force is applied against the force transmitting member urging it in a first direction along the axis of rotation of the valve member. Fluid pressure is applied against the force transmitting member to urge it in the first direction. A speed responsive control unit is operable to vary the fluid pressure applied against the force transmitting member as a function of variations in vehicle speed. The power steering resistance control system also includes a means for preventing an increase in the resistance to relative movement between the valve members as the vehicle speed increases when there is no relative movement between the valve members.

A variable assist power steering system for an automotive vehicle, the system having a source of hydraulic fluid (10), a power steering assembly (30) having a low speed inlet (32) and a high speed inlet (34), and a control valve (50) for continuously delivering hydraulic fluid to the low speed inlet and for delivering fluid to the high speed inlet only at vehicle speeds above a predetermined level. The control valve has an annular spool (64) which moves freely within a cylindrical housing (52), and it has a second spool (74) which is caused to move linearly by a solenoid (86) which acts on the one end thereof and a spring (88) which acts on the other end thereof. The second spool has a central portion (76) which is positioned within the annular spool and which defines an annular passage (68) therewith. The second spool further has enlarged end portions (78, 80) positioned outside of the ends of the annular spool to permit fluid to flow into the annular passage from each end. Energization of the second spool by the solenoid, which is accomplished in response to vehicle speed by speed responsive control devices (120, 130), will cause the annular spool to move with the second spool to maintain substantially balanced hydraulic flow into the annular passage from each of its ends. The annular spool has a flow path (66, 70) which communicates with the low speed inlet in both the solenoid energized and solenoid de-energized positions of the second spool, and a flow path (72) which communicates with the high speed inlet only in the solenoid de-energized position of the second spool.

Variable assist power steering control valve

A power steering control valve includes relatively rotatable inner and outer valve members. A power steering resistance control system resists relative rotation between the inner and outer valve members with a force which varies as a function of variations in vehicle speed. The power steering resistance control system includes a force transmitting member which is disposed adjacent to one end of an outer valve member. A spring force is applied against the force transmitting member urging it in a first direction along the axis of rotation of the valve members. Fluid pressure is applied against the opposite side of the force transmitting member to urge it in the opposite direction along the axis of rotation of the valve members. A speed responsive control unit, connected with a fluid return conduit for the power steering valve, is operable to vary the fluid pressure applied against the force transmitting member as a function of variations in vehicle speed. At relatively low vehicle speeds, the fluid pressure force applied against the force transmitting member is relatively large and it is easy to actuate the steering control valve. As vehicle speed increases, the fluid pressure force applied against the force transmitting member decreases and the resistance to actuation of the steering control valve increases.

An improved power steering apparatus includes a pressure modulation assembly which modulates the fluid pressure transmitted from a power steering control valve to a power steering motor. The modulation assembly varies the fluid pressure output from the steering control valve as a direct function of vehicle speed. This results in relatively easy steering for parking and low speed maneuvers and a firmer feel for maneuvers at higher speeds. The pressure modulation assembly is connected in series fluid communication with and between the power steering control valve and the power steering motor and includes a pair of pressure modulation valves. Fluid for actuating the power steering motor flows from the power steering control valve through the pressure modulation valves to the power steering motor. The pressure modulation valves are biased closed by the output pressure from an auxiliary pump which is driven at a speed which varies as a function of vehicle speed. Thus, the pressure of the fluid delivered to the power steering motor is reduced by the pressure modulation valve to an extent determined by the magnitude of the biasing force derived from the speed dependent auxiliary pump.

Vehicle steering apparatus

An improved power steering valve has a sleeve which circumscribes an inner valve member. An end mill or other rotary cutting tool is utilized to form axially extending grooves inside the valve sleeve. When the end mill is forming the grooves inside the valve sleeve, the axis of rotation of the end mill extends at an acute angle relative to the central axis of the valve sleeve. This results in a groove being formed with axially sloping end surfaces. In order to tend to maximize the compactness of the construction of the valve sleeve, fluid passages or holes are drilled along a sloping path from annular grooves on the outside of the valve sleeve to the sloping end surfaces of the axial grooves inside the valve sleeve. In addition, the compact construction of the valve sleeve is further promoted by forming some of the annular grooves with sloping bottom surfaces so that these grooves are relatively deep. This enables the width of these grooves to be reduced without reducing the capacity of these grooves to accommodate fluid flow.

Growing community of inventors

Rochester, MI, United States of America

Richard W Dymond