Machine element or mechanism – Control lever and linkage systems – Hand operated
Patent
1992-09-14
1994-02-22
Braun, Leslie A.
Machine element or mechanism
Control lever and linkage systems
Hand operated
74422, 180147, B62D 506
Patent
active
052877647
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for actuating a hydraulic power steering system for automotive vehicles having the following features: furnished with a pinion and is supported in a sleeve, about an axis, parallel in relation to the steering shaft, and it comprises a recess to enable the pinion to engage into the gear rack, and on it a pin-shaped extension is secured perpendicularly relative to the steering shaft, the extension actuating the valve slide of a steering valve designed as a linear slide valve, and stabilizes the support of the sleeve in the steering gear housing.
A device of this type is known from European patent application 0 291 155. In this prior art device, the sleeve is supported on that side of the steering shaft in the housing which is remote from the gear rack. The bearing is formed by a spherical indentation in the extension and a spherical shell-shaped recess in the steering gear housing. A disadvantage of this device is that high friction forces occur in the bearing because of the great radius of effect the friction force has due to the spring being pressed on. However, the strong spring is required to ensure freedom of play between gear rack and pinion. Further, the system has a tendency of being unstable since the force of the spring, which keeps the gear rack in contact with the pinion, induces a rolling motion of the steering shaft on the gear rack, the steering valve being actuated as a result. This might be a safety risk since the vehicle would be steered inadvertently in such a case.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to improve upon the known steering actuating device such as to render it stable in the neutral position and to nevertheless permit its actuation almost without losses due to friction. In addition, the inventive device is to have a degree of freedom of rotation solely in parallel to the steering shaft axis.
This object is achieved by the combination of the following features with the known features: two needles, and steering shaft center line than the point of force transmission between pinion and gear rack, and it is placed on the same side of the steering shaft center line as the latter point, and the valve slide is biassed by a captivated spring.
The design and arrangement of the needle bearings has, as a result, a small radius of effect of the friction forces which are caused due to the load on the spring, and thus permits an easy-motion actuation. The captivated spring stabilizes the valve slide in its neutral position.
In an advantageous improvement of the present invention, each of the needles is retained in an insert ring rigidly coupled to the steering gear housing. This measure permits an easy assembly of the insert rings with the needles in the steering gear housing. The second bearing part in the sleeve is formed in a straightforward fashion by annular extensions of the sleeve, fixed in relation to the needles by the force of a spring. In addition, the insert rings simultaneously serve as limiters (stops) for the rotary motion of the sleeve about the bearing axis. This results in reliable prevention of large roll off motions of the steering shaft and sleeve on the gear rack which might cause damage to the steering valve, the steering gear housing or the teeth of the gear rack.
A particularly simple assembly is made possible by a radial extension being screwed into a threaded bore of the sleeve. In this embodiment, the extension can be screwed in after the sleeve and steering shaft have been inserted into the gear housing.
In order to adjust a maximum possible valve travel in the event of slight roll-off motions of the sleeve and steering shaft, expediently, the radial extension is arranged perpendicular relative to the gear rack.
Other embodiments of this invention provide that the end of the radial extension which is not coupled to the sleeve is furnished with a spherical joint and is received in a recess of the valve slide. Also, the housing of the steering valve is
Alfred Teves GmbH
Braun Leslie A.
Lewis J. Gordon
Seitter Robert P.
Trousdell William O.
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