Motor vehicles – Compensating devices
Patent
1994-07-13
1995-09-19
Hill, Mitchell J.
Motor vehicles
Compensating devices
60384, 180132, 180149, B62D 504, F16D 4302
Patent
active
054509165
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an auxiliary power steering unit for motor vehicles consisting of a steering spindle--that can be driven by a steering hand wheel--with a steering gear. The auxiliary power acts as a torque for each turning direction, separated for one clutch unit at a time. Via reducing gears, the clutch units establish a drive connection from an auxiliary drive source that rotates only in one direction to a driven shaft that drives into the steering gear.
An auxiliary power steering of the design described above is known, for example, from DE 2746919A1. Here, an electric motor acts upon a conical pinion via a worm wheel and a free-wheel. The conical pinion drives two conical wheels in opposite directions and these wheels in each case are connected to clutch drums. Furthermore, there are provided clutch cheeks that cooperate with the clutch drums and that are connected to the steering spindles; when a rotary movement is initiated on the manual steering wheel which, upon initiation of a rotary movement on the manual steering wheel, press a pair of cheeks into the clutch drum that is driven in the same direction of rotation. In this way, one can support the manual rotary movement by means of the electric motor; in the process, the height of the support is proportional to the steering resistance that acts upon the steered wheels.
Considerable friction value fluctuations can occur during dry-runs along the clutch elements that work with friction coatings, so that under certain circumstances, the steering behavior will be influenced differently in the steering directions. Besides, with the lever ratios of the clutch cheeks provided, the setting ranges are comparatively long which, in turn, results in a delayed response behavior. One gets a comparatively large installation space by virtue of the complicated design of the clutch elements radially with respect to the steering spindle. Finally, one uses a comparatively expensive torsion bar in order to get a softly turning connection of the two steering spindle parts.
The purpose of the invention is to find a reasonably priced, electrically supported steering system where the auxiliary force is supplied uniformly without delay as a function of the supplied manual force. Another requirement is to house the steering system also in tight spaces.
The invention consists in the fact that clamping bodies guided in a common cage and acting in both directions of rotation are provided and that the clamping bodies act upon a common clamping sleeve that is subdivided into functional segments and that is slitted. The clamping sleeve rests with a small interval inside two clutch hubs that are driven in different directions of rotation by the reducing gear. The clutch unit gear works in such a way that--in case of a steering movement--as a function of the steering torque on the manual steering wheel, there will--by virtue of the clamping body--be a polygonal spreading of one of the two functional segments of the clamping sleeve against one or the other clutch hub. This spreading can be achieved by means of clamping slopes on the inside diameter of the clamping sleeve on which the clamping bodies run up. The clamping sleeve transmits the auxiliary torque, for example, of an electric motor upon the driven shaft in both directions of rotation.
The steering unit according to the invention works with small setting ranges so that the auxiliary torque can, without response delay, be fed into the driven [shaft] portion of the steering spindle. One gets uniform friction forces with minimum wear and tear because the clutch unit runs in a lubricating agent. Moreover, by means of the space-saving design of the clutch elements, one can achieve a rather cramped outer shape so that the steering system can also be used in smaller vehicles.
The invention is not confined to the combinations of features given in the claims. The experts will find additional meaningful possibilities of combining claims and individual claim features from the problem statement.
The invention will now be expla
REFERENCES:
patent: 3584985 (1971-06-01), Vagn Baatrup
patent: 4241804 (1980-12-01), Deininger et al.
patent: 5042250 (1991-08-01), Carlson et al.
Budaker Martin
Hagele Gerhard
Nagel Willi
Hill Mitchell J.
Zalkind Albert M.
ZF Friedrichshafen AG
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