Motor vehicles – Surface effect vehicles – Dynamic seal or fluid curtain
Patent
1991-01-29
1993-02-09
Focarino, Margaret A.
Motor vehicles
Surface effect vehicles
Dynamic seal or fluid curtain
180141, B62D 506
Patent
active
051846918
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
A servosteering system is described, for example, in DE-OS 29 06 047. Here, using an electrically-controlled three-way quantity regulator, oil volume is regulated for steering purposes as a function of the driving speed, as a result of which the steering forces are affected.
The disadvantage in this previously known steering system is that the steering forces depend on the quantity supplied to the servo-control unit. As the steering wheel is turned, however, oil flows to a speed responsive flow restrictor or throttle so that the oil quantity to the flow control edge of a control valve of the steering unit decreases as the steering speed increases. Thus, the effect of throttle variation requires more manual steering force for the same steering pressure in the steering servomotor. Accordingly, the steering force depends on the steering speed. This has a very disturbing effect, especially in case of a partially throttled quantity because the servomotor steering force increases greatly as the steering with increase of rate of turning of the steering wheel.
Another disadvantage is that the range within which the oil flow quantity can be varied is limited. It must not fall below a certain oil flow quantity; otherwise, the possible rate steering speed becomes too small. The maximum flow quantity must not be so big so that the pump will be overloaded and overheated. This means that the variation limits of the servomotor steering force is relatively limited at various driving speeds.
Another prior art arrangement is shown in DE-OS 32 03 450 in which surplus quantity of pressure medium will be kept approximately constant in the distribution valve in event of increased rotation of the steering wheel.
This construction provides a pressure valve separate from the distribution valve in which initial pressure regulation takes place. A regulating valve branches off in series with a fixed choke with an additional valve that can be adjusted parallel with the distribution valve. The choke characteristics of the additional valve is an image (in the two terminal segments of the adjusting distance) of the choke characteristics of the chokes that control a surplus volume beyond the servomotor.
However, in this arrangement effective changing of the oil flow cannot be accomplished so that a sufficient rate of steering would result.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1: a schematic illustration of the auxiliary power system according to the invention with a valve slide as distribution valve;
FIG. 2: an auxiliary power system according to the invention with a different design showing a 4/3-way valve as hydraulic distribution valve.
DETAILED DESCRIPTION OF THE INVENTION
The practical example illustrated in FIG. 1 shows a hydraulic supply 1, a quantity regulating valve 2, a pressure valve 3, and a distribution valve 4 from which a hydraulic servomotor 5 is supplied with pressure medium as a function of the axial position of piston 12 of distribution valve 4.
The hydraulic supply 1 consists of a servopump 6 that suctions a pressure medium, generally oil, from a tank 7.
The quantity regulating valve 2 works in a known manner, whereby the pressure differential is kept constant via variable restrictor 8. In this way, the aperture of variable restrictor 8 determines the quantity that flows to pressure control valve 3.
Between shutter 8 and pressure valve 3 there branches off a control line 28 to a spring chamber 29 with a spring 30. Via the force of spring 30 and pressure in control line 28, the position of the regulating piston 31 of the quantity regulating valve 2 is regulated as a function of the prevailing pressure conditions whereby, in case of a correspondingly high pressure in pump line 32, a down-regulation takes place into a tank. If piston 11 of the pressure valve 3 is shifted out of its neutral position, then the free cross section is reduced in accordance with the direction of shifting of regulating edge 9 or 10. In this way, a pressure rise occurs upstream of the pressure control valve 3,
REFERENCES:
patent: 4232708 (1980-11-01), Miller
patent: 4332303 (1982-06-01), de Maight
patent: 4541499 (1985-09-01), Yanai et al.
patent: 4798256 (1989-01-01), Fassbender
patent: 4811806 (1989-03-01), Lang
patent: 4815551 (1989-03-01), Lang
Focarino Margaret A.
Hurley Kevin
Zahnradfabrik Friedrichshafen AG.
Zalkind Albert M.
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