End-of-travel relief in a power steering system
AssigneeR.H. Sheppard Co., Inc.
InventorsJeffrey Tipton, Manjunath Terwad, Jared Pitzer
Life of this patent
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Abstract
An improved power steering assembly is provided. The power steering assembly includes an end-of-travel mechanism and a valve cartridge that is actuated by left and right actuator rings of the end-of-travel mechanism, the actuator rings extending partially around an output shaft. The actuator rings can be individually set for the desired end-of-travel relief to limit the maximum system pressure when the steering assembly approaches the desired axle stop setting. The valve cartridge provides an end-of-travel function and a pressure relief function and is in fluid communication with the left and right pressure chambers to recirculate hydraulic fluid in the event of a power off condition.
Claims20
A power steering assembly comprising:
- a sector gear moveable in clockwise and counterclockwise directions for right and left turn steering, the sector gear including a sector gear shaft extending therefrom;
- an end-of-travel mechanism mounted to the sector gear shaft, the end-of-travel mechanism including:
- a left actuator ring extending partially around the sector gear shaft and including a first cam extending radially therefrom,
- a right actuator ring extending partially around the sector gear shaft including a second cam extending radially therefrom;
- and
- a valve cartridge including at least one poppet valve engageable by the first cam in response to rotation of the sector gear in a first direction.
A valve cartridge for an end-of-travel mechanism having left and right actuator rings extending partially around an output shaft, the valve cartridge comprising:
- a valve housing;
- and
- at least one poppet valve contained within a bore defined within the valve housing, the at least one poppet valve being adapted to be engaged by the left and right actuator rings and including a valve head for engaging a valve seat defined by the valve housing,
- wherein the at least one poppet valve is adapted to provide end-of-travel relief for a hydraulic steering assembly, and wherein the at least one poppet valve is adapted to be in fluid communication with first and second pressure chambers on opposing sides of a steering piston.
A valve cartridge for an end-of-travel mechanism having left and right actuator rings extending partially around an output shaft, the valve cartridge comprising:
- a valve housing including a first port that opens to a first internal chamber and a second port that opens to a second internal chamber, the valve housing including a valve seat that interconnects the first internal chamber with the second internal chamber;
- a poppet valve contained within the valve housing and including a valve head partially housed within the first internal chamber, a valve body at least partially housed within the second internal chamber, and a valve stem extending between the valve head and the valve body;
- and
- a compression spring to bias the valve body against the valve seat, thereby closing the first internal chamber from the second internal chamber, wherein the poppet valve is adapted to provide end-of-travel relief for a hydraulic steering assembly in response to actuation of the left and right actuator rings and adapted to provide pressure relief to first and second pressure chambers on opposing sides of a steering piston.
Dependencies are inferred from the claim text.