Motor vehicles – Surface effect vehicles – Dynamic seal or fluid curtain
Patent
1994-08-05
1996-04-23
Hill, Mitchell J.
Motor vehicles
Surface effect vehicles
Dynamic seal or fluid curtain
180141, 180148, B62D 522
Patent
active
055094937
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a steering-rack-equipped auxiliary power steering, especially for motor vehicles. In this kind of auxiliary power steering, a pinion is positioned rotatably in a steering housing. A steering rack is guided in an axially movable fashion in the steering housing and is maintained so as to engage the pinion by means of a spring-loaded thrust piece. A servomotor is used to support the auxiliary power steering; this servomotor is connected with the steering rod in a driving manner. A control device for steering a pressure agent to and from the servomotor can be adjusted as a function of a movement of the pinion.
2. Description of the Prior Art
Such a steering-rack-equipped auxiliary power steering is known from EP-B1-01 92 641. In this design, tile oblique gearing of the pinion generates a force component upon the pinion in an axial direction so that the pinion will be adjustable in an axial direction. The control valves can be adjusted by means of this axial shifting of the pinion.
To ensure perfect operation of the control valves, the slope angle of the pinion should, if at all possible, be more than 35 degrees. In that way, the choice of pinion gearing is heavily restricted. The activation of the control valves can be impaired in that the lateral forces that act upon the steering rack are braced upon the pinion and call thus increase the friction for the axial shifting of the pinion. The known steering-rack-equipped auxiliary power steering can then not be used when only a limited structural space is available in the area of the diameter of the pinion housing.
The purpose of the invention is to prevent the described shortcomings without any additional design effort. In particular, it should be possible to use pinions with differing helix angles slope angles!, in other words, also with helix angles of less than 35 degrees.
SUMMARY OF THE INVENTION
This problem is solved by the steering-rack-equipped auxiliary power steering. The solution is accomplished particularly inasmuch as the pinion is positioned swingably on a fixed bearing and a movable bearing. Here, the control device is made in the form of two control valves that are arranged in the area of the movable bearing. The control valves have valve seats whose axes are positioned essentially perpendicularly to the axis of the pinion. This means that to activate the control valve, one does not make use of the axial forces acting upon the pinion, but instead, one uses the lateral forces. If one turns the steering spindle, then the gearing of the pinion will first roll off in the gearing of the still fixed steering rack and will thus move the bearing journal of the pinion that is guided in the loose bearing, so that one of the control valves will be adjusted. If one uses seat valves in the control valves, then very small movements of the pinion will suffice to activate and control the control valves. By means of these minimal control paths and the connected minor movements of the pinion in its movable bearing, it is possible to position the pinion on one side, for example, on the side of the steering spindle with a fixed bearing. The swing angle of the pinion is then so small that the set within the gearing remains within the permissible range.
Practical and advantageous versions of the invention are given in the subclaims. But the invention is not confined to the combination of features given in the claims. The expert will find additional meaningful combination possibilities of claims and individual claim features from the problem statement.
The invention will be described in greater detail below with the help of a practical example illustrated in the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal profile through a steering-rack-equipped auxiliary power steering according to the invention;
FIG. 2 is a partial cross section through the steering-rack-equipped auxiliary power steering in FIG. 1 in the area of the pinion.
DESCRIPTION OF THE PREFERRED EMBO
REFERENCES:
patent: 4607717 (1986-08-01), Nakayama
patent: 4779694 (1988-10-01), Adams
patent: 4834202 (1989-05-01), Shimizu
Knodler Helmut
Lang Armin
Hill Mitchell J.
ZF Friedrichshafen AG
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