Machine element or mechanism – Control lever and linkage systems – Hand operated
Patent
1991-04-26
1992-08-18
Herrmann, Allan D.
Machine element or mechanism
Control lever and linkage systems
Hand operated
74422, 74440, B62D 308, F16H 5712
Patent
active
051388960
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a steering gear, especially for motor vehicles. Such a steering gear has a steering worm sector shaft including a toothed quadrant and a steering nut engaging with the toothed quadrant with a steering rack section and displaceable axially by a steering shaft. To eliminate the play between the toothed quadrant and the steering rack section that occurs after rather lengthy operation, a spring pressure element is provided. It is located outside the surface plane containing the steering shaft axis and perpendicular to the toothing surface plane of the steering rack section and exerts a twisting force on the steering nut when the steering gear is in a straight-ahead-travel position.
BRIEF DESCRIPTION OF THE PRIOR ART
Such a steering gear is known from DE-PS 27 35 958. In that known steering gear, the spring pressure element consists of several individual parts--specifically, a pressure pin, a spring and a nut. In fact, adequate automatic compensation for tooth play is possible with the known apparatus. However, since the spring pressure element consists of several individual parts, the expense of production and assembly is relatively high.
The object of the invention is to make the device for automatic tooth play compensation in the form of a compact spring pressure element which is easy to assemble and economical, and to install it in place in the known steering gear.
SUMMARY OF THE INVENTION
A primary object of the invention relates to making the spring pressure element as a one-piece part and locating it between the steering worm sector shaft and the steering rack section. It is especially advantageous if the spring pressure element consists of two spring washers, located concentrically with each other on the steering worm sector shaft, that are connected with each other. The outer spring washer is supported by the steering rack section with prestressing, with an extension directed radially outward in straight-ahead travel, and the side of the inner spring washer facing the steering rack section is supported by the steering worm sector shaft. Since the spring pressure element is a one-piece part, it can easily be produced as a stamped metal part, a gas-cut part, a laser-beam-cut, or as a waste-wax casting. The spring pressure element can very easily be slid onto the end of the toothed quadrant of the steering worm sector shaft instead of a check plate on the steering worm sector shaft.
If the extension of the outer spring washer is fitted to the toothing of the toothed quadrant, and especially if the extension has the shape of the center tooth of the toothed quadrant, a "shifting pressure point" is obtained together with the steering rack section of the steering nut. As a result, the reverse travel characteristics of the steering gear are retained, and only very small additional frictional forces arise in the neutral position in spite of the spring tension.
To obtain adequate strength of the spring pressure element against fatigue, the two spring washers are made with a tension-optimized cross-sectional pattern. That means that the spring washers are made correspondingly wider in the areas that are under greater stress.
Since automatic tooth play compensation is necessary only in a limited area on both sides of the straight-ahead-travel position in which the greatest wear on the toothing occurs, the spring pressure element is designed only for that area. That means that at least the outermost of the two spring washers must be held rotation-proof on the steering worm sector shaft.
BRIEF DESCRIPTION OF THE DRAWING
In the following specification, the invention is explained in greater detail with the help of an example that is shown in the drawings, in which:
FIG. 1 shows a longitudinal section through the steering gear of the invention;
FIG. 2 shows a cross section through the steering gear of FIG. 1; and
FIG. 3 shows an enlarged plan view of the spring pressure element.
DETAILED DESCRIPTION
A conventional steering gear contains, in a steering ge
Elser Dieter
Schurr Rudolf
Herrmann Allan D.
Zahnradfabrik Friedrichshafen AG
Zalkind Albert M.
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