Power-assisted steering system
AssigneeRegie Nationale des Usines Renault
InventorsAlain Dera, Georges Itey-Bernard
Life of this patent
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Abstract
A power-assisted steering system for a motor vehicle comprises a flexible tie, the ends of which are wrapped in opposite directions around, and are anchored to drums which turn with the steering movements of the steerable guiding wheels. The tie carries at its center, rollers which follow fixed cams. The profiles of the cams are such that, during the steering of the wheels under the action of two hydraulic rams acting through racks and pinions fixed to the drums, the wheels always turn about a single common instantaneous center of turning. The rams are controlled by a distributor valve which is in turn controlled by a rocking lever which is actuated by Bowden wire cables from a steering wheel. The system is especially applicable to load handling trucks having small turning circles.
Claims6
A power-assisted steering system for a motor vehicle comprising a pair of guiding wheels;
- substantially vertical pivot means mounting said guiding wheels for steering turning movement;
- a manually operable steering device;
- a pair of drums;
- means rotatably mounting said drums for turning movement, one with each of said guiding wheels;
- a non-elastic flexible tie, said tie having two end portions and an intermediate portion;
- means anchoring one said end portions to each of said drums with said end portions being wrapped in opposite senses one around each of said drums;
- a pair of double-acting rams each having a first portion connected to the chassis of the vehicle and a second portion movable with respect to the chassis of the vehicle, each of said second portions cooperating with said pivot means to turn one of said guiding wheels as said second portions move with respect to the chassis of the vehicle;
- a distributor valve capable of assuming any one of three valve positions, said distributor valve in the first valve position adapted to couple a hydraulic source to said rams to move said second portions in a first direction relative to the chassis of the vehicle to turn the guiding wheels in a first direction, said distributor valve in the second valve position adapted to couple the hydraulic source to said rams to move said second portions in a second direction relative to the chassis of the vehicle to turn the guiding wheels in the opposite direction, said distributor valve in the third valve position adapted to isolate the hydraulic source from said rams;
- control means responsive to operation of said steering device for causing said distributor valve to assume one of the three valve positions;
- at least one roller mounted on said intermediate portion of said tie;
- and at least one cam secured to the chassis of the vehicle and cooperating with said roller to deform said intermediate portion of said tie as said guiding wheels turn, whereby said steering system provides differential turning of said pair of guiding wheels to cause said pair of guiding wheels to have the same center of turning.
Dependencies are inferred from the claim text.