Servosteering, especially for motor vehicles

Details Servosteering, especially for motor vehicles Servosteering, especially for motor vehicles

1984-08-23

1985-12-10

Pekar, John A.

Motor vehicles

Including one or more ski-like or runner members

With at least one surface-engaging propulsion element

91371, B62D 508

Patent

active

045573441

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

It has been known basically to vary the simulated resistance to manual steering effort by way of increased resistance in response to increase in vehicle speed. For example, the U.S. patent to Uchiyama et al, U.S. Pat. No. 3,690,400 shows such an arrangement and other patents in the field are German DE-PS No. 21 27 070 and German DE-GM No. 80 29 580.
In particular, the patents or applications of Armin Lang, assigned to the present assignee, viz., German DE No. 31 22 370 (application), which became the present U.S. Pat. No. 4,438,827 and U.S. Pat. No. 4,462,478, are of particular pertinence as background art in that they show arrangements utilizing control valve means such as integral coaxial piston valves and separately movable piston valves, including fixed throttles in lines from the chambers of a double acting servomotor to reaction chamber of the valves for exerting pressure forces in opposite directions.
U.S. Pat. No. 4,438,827 is relied on for the closest background of the present invention and is hereby incorporated by reference along with U.S. Pat. No. 4,186,818 of Jablonsky, likewise assigned to the present assignee.
Thus, in the disclosure herein it will be understood by persons familiar with the art that the mechanical force which returns the reciprocal valve means to a neutral position after a steering operation is effected by springs such as 62, 62A, as shown in U.S. Pat. No. 4,186,818, FIG. 3. Also, the arrangement of a rotary valve housing which carries the reciprocal valves, as used in most of the modifications herein is shown in that patent together with conventional structure as shown to complete an operative booster steering device familiar to persons skilled in the art.


BRIEF DESCRIPTION OF THE INVENTION

All modifications use a manually shifted control valve of the reciprocal spool or piston type for each chamber of a double acting servomotor. In one modification the valves are in a fixed housing and in other modifications the valves are in a rotative housing of a heretofore known type as shown in U.S. Pat. No. 4,186,818 heretofore mentioned, and for the basic construction, it is shown and described in U.S. Pat. No. 4,438,827.
The latter patent shows arrangements of control valve means, one such valve mean for each chamber of a double acting servomotor. Thus, the valve means being in the form of piston valves, spaced collars are provided which coact with edges of grooves in housing bore means in which the piston valves are shiftable by manual effort on a steering wheel.
There are flow control gaps between collar edges and groove edges which are open in neutral position whereby the output of a servopump flows through to a tank and to the chambers of a servomotor. Thus, each piston valve has an inlet flow control gap and a return flow control gap and a reaction chamber.
The servomotor has a housing passage for each chamber and each housing passage is located between the inlet and return flow control gaps of a respective piston valve.
Dependent upon a steering operation and via a speed responsive variable throttle, connecting from a tank through fixed throttles to the reaction chambers, pressures in the housing can open check valves leading to the reaction chambers for producing a differential of pressure therein for simulated steering resistance.
As a novel feature of the present invention a balanced force during slow speed parking is realized so that the vehicle driver need not work against simulated steering resistance. However, upon increase of speed and especially at high speeds suitable steering resistance is effected as a safety measure.
Accordingly, the advantage of ease of parking effort but increase of steering resistance with speed is achieved. Further, the invention provides for simulated steering resistance occurring at higher speeds before booster support occurs. Thus the mechanical valve centering forces can be kept low in order to keep parking effort low, but safety is assured by an equivalent of a high mechanical centering force by virtue of

REFERENCES:
patent: 3690400 (1972-09-01), Uchiyama et al.
patent: 4119172 (1978-10-01), Yanagishima et al.
patent: 4186818 (1980-02-01), Jablonsky
patent: 4274504 (1981-06-01), Kawabata et al.
patent: 4438827 (1984-03-01), Lang
patent: 4462478 (1984-07-01), Lang

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