Machine element or mechanism – Control lever and linkage systems – Elements
Patent
1991-01-02
1993-05-18
Luong, Vinh T.
Machine element or mechanism
Control lever and linkage systems
Elements
74531, 384513, 384906, G05G 506, F16C 3358
Patent
active
052110737
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to devices for generating axial forces in rotating shafts and, more particularly, to a device for generating an axial counterforce in a rotating shaft in response to axial displacement thereof.
In electrically powered steering arrangement in motor vehicles, for example, it is important to provide a controllable axial counterforce in response to axial displacement of a rotating shaft. Moreover, arrangements for providing such an axial counterforce to a rotating shaft are useful in many fields of engineering wherever axial counterforces must be applied in opposition to axial forces exerted on a rotating shaft, for example, to generate thresholds for open- or closed-loop control steps to be performed by the shaft.
In the context of fully electric power steering equipment for motor vehicles, an arrangement of this type is known, for instance, from FIG. 5 of German Offenlegungsschrift No. DE-OS 36 12 619. In the apparatus disclosed therein, a detent device in the form of a radially movable control pin urged toward a shaft by a preferably controllable radial force engages a circumferential shaft ring groove having flanks inclined away from the groove bottom. As a result, any axial displacement of the shaft generates an axial force that is dependent, among other factors, on the magnitude of the radial force applied by the pin and o the shape of the groove flanks. This axial force acts in a direction to counter the axial force displacing the shaft.
Because the axial distance along which the detent device can act on the shaft groove for control purposes is short, however, comparatively high radial forces must be applied by the pin.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an arrangement of generating a counterforce in response to axial displacement of a rotating shaft which overcomes the above-mentioned disadvantages of the prior art.
Another object of the invention is to provide an arrangement of the above type which provides more precise control of the magnitude of the axial counterforce applied to the shaft.
These and other objects of the invention are attained by providing a ball bearing arrangement in axially fixed position with respect to an axially movable shaft and a radial recess in the outer race of the ball bearing arrangement having flanks inclined with respect to the shaft axis, along with a radially movable detent device urged toward the recess. Preferably, the outer race recess is in the form of a groove extending transversely to the shaft axis and the end of the detent device engaging the groove includes a rotatable roller with its axis aligned transversely to the shaft axis.
With the apparatus according to the invention, it is possible to achieve very precisely defined axial counterforces in the rotating shaft which do not change over a very long period of operation because virtually no wear occurs despite comparatively high radial forces applied by the detent device.
In one embodiment, the inner race of the ball bearing arrangement comprises a groove machined directly into the shaft so that the shaft itself serves as the inner bearing race. Preferably, a split outer bearing race is provided in which the parting line is in a plane extending approximately perpendicular to the radial force applied by the detent device and approximately at the position of the shaft axis.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings in which:
FIG. 1a is a fragmentary side view, partially in longitudinal section, illustrating a representative embodiment of the invention;
FIG. 1b is a cross-sectional view illustrating the embodiment shown in FIG. 1a;
FIG. 2a is a fragmentary side view, partially in longitudinal section, illustrating another typical embodiment of the invention;
FIG. 2b is a cross-sectional view of the embodiment of the invention shown in FIG. 2a;
FIG. 3a is a
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Nikl Horst
Weissbrich Alfons
Luong Vinh T.
Volkswagen AG
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