Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Patent
1991-01-29
1992-08-18
Hill, Mitchell J.
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
91375A, 91401, 91437, B62D 508, F15B 910
Patent
active
051391066
DESCRIPTION:
BRIEF SUMMARY
The object of the invention is to improve the operation and construction of known auxiliary power steering systems that effect valving to limit the power stroke.
BACKGROUND OF THE INVENTION
An auxiliary power steering system is known from DE-PS (German patent) 1,750,263. Such design is disadvantageous in case of reversal of the steering direction when the servopiston is to be reversed from the end of a power stroke in an opposite steering direction toward the direction of neutral position. The initial movement must take place without auxiliary power support but by human force on the manual steering wheel. Only after the servopiston has been reversed a distance toward neutral position can flow connection between the two working chambers of the servocylinder be interrupted and servopressure used to reverse the servopiston.
SUMMARY OF THE INVENTION
The invention comprises a channel member having a bore and being fixed in the working cylinder extending between the end walls thereof. The servopiston has a bore through which the channel member extends sealingly while the servopiston rides up and down in the servocylinder.
Transverse bores are provided through the channel member at spaced distances which are predetermined to control the extent that the servopiston will move after pressurization of either chamber to a point where it will stop short of effecting further steering force before the vehicle steering linkage is mechanically stopped by engagement with an abutment in each direction of steering.
Each face of the servopiston has a flow control edge that coacts with a respective transverse bore to permit flow from the pressurized chamber to the opposite chamber, viz., the chamber connected to a tank.
Accordingly, both chambers are at tank pressure whereby power stroke of the servopiston ceases.
At that point the driver of the vehicle can reverse the steering direction with virtually immediate pressurization by use of a conventional steering control valve. Thus, the chamber into which the pressurized chamber transfers its pressure flow can be quickly pressurized in the event that the driver wishes to reverse the first direction of steering.
In order to prevent loss of pressure when either working chamber is pressurized an ordinary ball check valve means is used in the respective end of the channel member in each working chamber.
BRIEF DESCRIPTION OF THE DRAWING
The single FIG. 1 of the drawing shows a longitudinal section through the essentials of the invention.
DETAILED DESCRIPTION OF THE INVENTION
A steering gear housing contains a servocylinder 2. In servocylinder 2 a servopiston 3 is reciprocally movable and divides the servocylinder 2 into working chambers 4 and 5.
It will be understood that the arrangement is conventional and pressurization of one chamber is effected while tank connection of the other chamber is effected, controlled at the will of a vehicle driver who utilizes conventional valving (not shown) responsive to rotation of the steering wheel for selectively pressurizing one chamber while providing for return oil to a tank of the other.
A flow channel member 12 in the form of a rod-like tube passes with a sliding relationship as the servopiston reciprocates wherein the rod-like tube fits sealingly in a bore 11 of the servopiston 3. It will be understood that the channel member 12 as well as the bore are parallel to the axis of the servocylinder and that the respective ends 13 and 14 of the channel member engage against the end walls 15 and 16 of servocylinder 2 the channel member being stationary.
Channel member 12 has a longitudinal flow channel bore 17 as well as two predeterminedly spaced transverse bores 18 and 20. The spacing between bores 18 and 20 and the ends 14 and 113 of the channel member 12 essentially corresponds to a predetermined portion of the length of the servopiston 3.
By reference to the changes shown in red the drawing filed for approval has vertical arrows drawn for directions of reversible movement of the piston, the length of the arrows corresponds to the p
REFERENCES:
patent: 4285266 (1981-08-01), Elser
patent: 4367672 (1983-01-01), Elser
patent: 4368794 (1983-01-01), Elser et al.
patent: 4373598 (1983-02-01), Elser
patent: 4417501 (1983-11-01), Elser
patent: 4648307 (1987-03-01), Rabe
patent: 4773303 (1988-09-01), Stroud
Elser Dieter
Holub Heinrich
Hill Mitchell J.
Zahnradfabrik Friedrichshafen AG
Zalkind Albert M.
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