Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Patent
1988-01-29
1989-06-13
Pekar, John A.
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
91434, B62D 508
Patent
active
048383759
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a steering system, and more particularly to a steering system of the fully-hydraulically-operated type for use in construction, vehicles, industrial vehicles and the like.
BACKGROUND TECHNIQUE OF THE INVENTION
As for the conventional gear of the kind specified, there has so far been known one which is shown, for example, in Japanese Patent Application Laid-open Specification No. 49-89203.
This conventional steering system has been constructed such that a valve spool is axially moved by the rotation of the steering wheel and the fluid under pressure is supplied, at a flow rate corresponding to the amount of movement of the valve spool, from a gyratory rotor into a steering cylinder through a port whose area of opening is controlled by the movement of the above-mentioned valve spool so that a steering operation corresponding to the angle of rotation of the above-mentioned steering wheel may be made by the action of the fluid pressure force.
In the above-mentioned conventional steering system, since an operating force which is approximately proportional to the amount of movement of the valve spool occurs in the steering wheel, when the fluid pressure is increased for operating the steering wheel while the vehicle is stopped or when quick steering is made by turning the wheel quickly, a large steering force is required. Therefore it has been required to improve the operating performance of the steering wheel.
In the meantime, when a reaction force device such as a torsion bar or a leaf spring, is set lightly to improve the above-mentioned disadvantage, disadvantageous phenomena occur. For example, the reaction or response transmitted through the steering wheel when the vehicle is running straight cannot be sensed by the driver thus giving him a sense of unease moreover, the stability of the vehicle when running at high speeds becomes lower.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned situation in the conventional steering system, and has for its object to provide a steering system which provides an improved stability in manipulating the steering wheel when the vehicle is running at high speeds without impairing the operability of the steering wheel when the vehicle is running at low speeds.
To achieve the above-mentioned object, according to the present invention, there is provided a steering system of a fully-hydraulically-operated type constructed such that the fluid under pressure is supplied, at a flow rate corresponding to the amount of rotational movement of an actuating shaft adapted to be rotatively driven by the turning operation of the steering wheel, through a port whose area of opening is controlled by the amount of rotational movement of the actuating shaft, and then through a fluid measuring unit into a steering cylinder so that a steering operation corresponding to the amount of rotation of the steering wheel is made by the action of the fluid pressure force and the amount of pressurized fluid supplied into the steering cylinder, characterized in that the invention comprises an apparatus for regulating the actuating force applied by the actuating shaft by the action of the fluid pressure force to be controlled in accordance with the running speed of the vehicle.
Further, according to the present invention, there is provided a steering system, characterized in that the apparatus for regulating the actuating force applied by the actuating shaft includes a valve spool slidably inserted in the valve bore formed in a valve housing so that it may be axially moved in accordance with the amount of rotational movement of the actuating shaft; a piston portion projecting as an integral unit of a part of the outer periphery of the valve spool and along the outer periphery and which is kept in sliding contact with the inner peripheral surface of the valve housing formed or machined in a part of the inner periphery of the valve bore and along the inner periphery; two annular pressure chambers form
REFERENCES:
patent: 3834278 (1974-09-01), Goff et al.
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Pekar John A.
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