Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Patent
1986-05-30
1989-03-28
Mitchell, David M.
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
180141, 91371, B62D 506
Patent
active
048155519
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
German Pat. No. OS 31 22 370, the counterpart of which is U.S. Pat. No. 4,438,827 to Armin Lang, the applicant herein, shows a system of speed responsive control of reaction chamber pressure wherein a pressure reduction valve is located between a speed responsive throttle and a fixed throttle connected to each of the reaction chambers of a manually operated servosteering control valve. The pressure from the pressure reduction valve is constant and can be felt in the reaction chamber or chambers at high and low speeds. In a low speed tight turn when the exit pressure of the speed responsive valve would rise even at low speed, the vehicle operator would have to use the effort necessary to overcome the maximum exit pressure of the pressure reduction valve which will always be the same, as indicated in the graph of FIG. 6 of this application.
Thus, at low speeds in tight turns the force of turning the steering wheel is excessive under the circumstances and occasions driver discomfort.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
The improvement effected herein has a different arrangement by which the maximum steering force felt by the driver decreases with decreasing vehicle speed, depicted in the graph of FIG. 7 of this application.
Such improvement is brought about by making reaction force to be overcome by the driver dependent on vehicle speed, which force decreases with vehicle speed. Thus, the sequence of connection is such that the pressure reduction valve responds to the pressure difference between the upstream and downstream sides of the speed responsive throttle valve in series with a fixed throttle valve.
The pressure reduction valve is connected either upstream or downstream of the series arrangement.
The result is that in slow tight turns the vehicle driver does not have to exert the manual effort that was required by the prior art arrangement.
The particular distinction between the background of the invention is clearly brought out in comparing FIG. 3 of U.S. Pat. No. 4,438,827 with the present invention. In the prior patent, the pressure reduction valve 42 is in series between the speed responsive throttle 22 valve and one of the fixed throttles 20 or 21, depending on direction of steering. In the present invention, e.g., FIG. 1, the pressure reduction valve 26 is in series with but before the speed responsive throttle valve 22 and a fixed throttle depending on direction of steering.
Thus, in the present invention, a respective check valve in the servomotor steering control valve piston 6 will open to establish a connection for the pressure reduction valve to be in parallel across the speed responsive valve in series with a fixed throttle.
A detailed description of the drawing now follows in conjunction with the appended drawing in which:
FIG. 1 shows a schematic presentation of a preferred form of the invention;
FIGS. 2-5 show various embodiments of the system;
FIG. 6 shows characteristic lines at various speeds in a graph of a servosteering system of the prior art;
FIG. 7 shows a graph of characteristic lines at various speeds in a servosteering of the invention.
Referring to FIG. 1 which shows the most preferred embodiment, there is shown a steering control valve 1 for a steering linkage (not shown) wherein a pressure agent e.g. oil, is fed to a booster cylinder or servomotor 2 from a servopump 3 and after being utilized in the system ultimately returns to a tank 4.
The steering control valve 1 has a piston 6 in a valve housing 5 which piston is shiftable as by a steering wheel, is indicated by phantom lines in FIG. 1.
Pressure fluid from servopump 3 feeds into two annular housing grooves 7 and 8. Two piston grooves 9 and 10 of piston 6 connect by respective lines 11 and 12 with respective pressure chambers of servomotor 2. A centered annular groove 13 of the housing is connected via a return line 14 with a tank 4.
At the ends of piston 6 there are respective reaction chambers 15 and 16. From the reaction chambers 15 and 16 respective reaction pressure lines 17 an
REFERENCES:
patent: 3922953 (1975-12-01), Strauff
patent: 4071109 (1978-01-01), Ezoe
patent: 4344284 (1982-08-01), Lang
patent: 4385493 (1983-05-01), Lang
patent: 4390158 (1983-06-01), Lang
patent: 4438827 (1984-03-01), Lang
patent: 4462478 (1984-07-01), Lang
patent: 4557344 (1985-12-01), Lang
McGiehan Donn
Mitchell David M.
Zahnradfabrik Friedrichshafen AG
Zalkind Albert M.
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