Motor vehicles – Steering gear – With fluid power assist
Patent
1998-06-10
2000-05-30
Hurley, Kevin
Motor vehicles
Steering gear
With fluid power assist
91372, B62D 5087
Patent
active
060680776
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a power steering system, in particular for motor vehicles. The power steering system includes a steering valve, for controlling pressure medium for a servomotor, has two inlet seat valves and two outlet seat valves, each with one closing body. The closing bodies of the outlet seat valves are actuatable by an actuating device as a function of the rotary motion of a steering-wheel shaft connected to an input member of the steering system. The closing bodies of the inlet seat valves are hydraulically pressure balanced with reference to a pressure of a pressure source, and by the force of locking springs they keep the inlet seat valves closed in the neutral position of the steering valve. Each locking spring is supported at one end on a closing body of one of the inlet seat valves and on the other by the actuating device. The outlet seat valves are open in the neutral position of the steering valve. The effective cross section of the closing bodies of the outlet seat valves is smaller than the effective cross section of the closing bodies of the inlet seat valves.
2. Brief Description of the Prior Art
One such power steering system is known from German Patent Disclosure DE 43 03 854. In an exemplary embodiment of this known power steering system, a rack-type power steering system is described. The actuation of the steering valve is done by a pivoting motion of the pinion. The inlet seat valves and the outlet seat valves are disposed such that their axes are substantially at right angles to the axis of the pinion. The valves are disposed in a lower region of the pinion, below the rack. In motor vehicles, there is often only a very constricted space available in this region of the power steering system.
SUMMARY OF THE INVENTION
The object of the invention is to create a power steering system in which the steering valve is very compact and can therefore be accommodated in a space-saving way.
This object is attained by the power steering system described herein. Specifically, in a power steering system of the generic type in question, the steering valve is disposed between the input member and an output member of the steering system. The actuating device has at least one actuating lever for actuating the outlet seat valves. As a result of this embodiment, the steering valve can be accommodated in the upper portion of the power steering system. This is made possible by the fact that because of the actuation via the actuating lever, the control paths of the seat valves can be longer than when actuation is by a pivoting pinion. Because of the longer stroke of the valves, the requisite cross-sectional flows can be achieved with smaller valve diameters.
Expedient and advantageous features of the invention are described herein. However, the invention is not limited to the combination of characteristics described herein. For one skilled in the art, further logical possibilities of combining features and individual characteristics will be apparent from the stated object.
The actuating lever is expediently solidly connected to the input member of the steering system. Depending on structural conditions, it is possible to provide either a separate actuating lever for each of the outlet seat valves or one common actuating lever, in particular with two arms, for both of the outlet seat valves.
The closing body of the outlet seat valve cooperates either directly or indirectly with the actuating lever that is engaged by the locking spring. An actuating pin can be kept in operative connection with the actuating lever by means of an actuating spring. The closing body of the outlet seat valve can be embodied either separately from or integrally with the actuating pin.
To enable a general introduction of force upon a rotation of the input member, a lead spring may be disposed between the input member and the actuating device. The lead spring may be disposed between the input member and the actuating lever. Another, structurally simple possible way of
REFERENCES:
patent: 3922953 (1975-12-01), Strauff
patent: 3967537 (1976-07-01), Strauff
patent: 4555975 (1985-12-01), Lang et al.
patent: 5529137 (1996-06-01), Lang
Abele Wolfgang
Frohlich Stefan
Knodler Helmut
Lang Armin
Hurley Kevin
ZF Friedrichshafen AG
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