Atsugi Motor Parts Company, Limited

Seiji Uemura

Koichi Komatsu

Shinich Komatsu

A power-assist device for an automotive steering system employs an easy-to-assemble hydraulic pressure control valve to compensate for differential forces on opposite sides of an actuating piston in an unbalanced hydraulic cylinder. The piston divides the cylinder into first and second working chambers which are each connected to a hydraulic pump and a return reservoir via first and second spool valves, respectively. The spool valves are actuated axially by a torsion bar connected to the stub shaft of the steering column, so that they reciprocate axially within bores through the valve body as the steering wheel is turned back and forth. Lands on the spool valves oppose slightly larger lands the bores to define orifices which control the rates of hydraulic supply and drain to and from the working chambers of the cylinder. The cross-sections of the orifices change as the spool valves reciprocate and the first-chamber supply and second-chamber drain orifices are larger than the others due to the increased internal diameters of the corresponding bore lands. This boosts the hydraulic pressure in the first working chamber in order to compensate for its reduced effective piston area, which is due to the effect of a piston rod connecting the piston to wheel-orientation control mechanisms. The first and second spool valves are identical; the bores are contoured differentially to provide the necessary dimensional differences among the control orifices.

Power assist device for automotive steering system

A rack-and-pinion steering gear structure for a vehicle including a rack housed within a cylinder and driven by means of a pinion shaft, comprises an annular piston received with suitable axial clearance in an annular groove defined by three surfaces, namely the end face of one end of the rack, a seating surface of a head of a bolt screwed into a boss projecting from the end of the rack, and the outer periphery of the boss itself. An elastic annular seal member is interposed between the inner periphery of the piston and the outer periphery of the boss.

Rack-and-pinion steering gear structure for a vehicle

A rack-and-pinion steering gear structure for a vehicle including a rack housed within a cylinder driven by means of a pinion shaft, comprising: a bolt having a threaded portion screwed in a threaded hole formed in one end face of the rack and a shoulder linked integrally with the threaded portion and smaller in diameter than the rack but greater in diameter than the threaded portion; and a piston housed within a groove formed by the shoulder of the bolt, the seating surface of the bolt head, and the end face of the rack, with clearances with respect to the groove in the axial and radial directions.

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Kanagawa, Japan

Seiji Uemura