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US 2003/0154715 A1Published application
Motion stop control for vehicle
AssigneeClark Equipment Company
InventorScott N. Schuh
Life of this patent
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AssigneeClark Equipment Company
InventorScott N. Schuh
Estimating the term…
A self-propelled vehicle, such as a loader, has a hydrostatic drive that includes hydrostatic motors to drive ground engaging wheels under control of the operator. The rotational speed of the motors is proportional to an operator control input provided to a controller which in turn regulates the flow of hydraulic fluid under pressure from a pressure source to the motors. In the form shown, the regulation of the hydraulic fluid under pressure to the motors is achieved by utilizing electrical displacement control pumps that will provide a flow of fluid to a connected motor in direct proportion to an input signal as the flow source. The motors are fixed displacement motors, and when the wheels tend to overrun as the vehicle rolls down a hill or incline, the motors will act as pumps. The movement of the wheels is sensed to provide a signal to the controller to adjust one or both of the electrical displacement control pumps to provide a balancing counter pressure at the high pressure side work port of the associated motor to insure that the vehicle will not creep or roll when it should be stopped.
A motion stop control for stopping rotation of a hydrostatic motor when operating as a pump driven by a wheel, comprising a pressure source coupled to said motor, an operator control providing an input signal to indicate a desired amount of rotation of the motor, said operator control input signal adjusting the hydraulic power delivered by the pressure source to the motor, a sensor for sensing rotation of the wheel driven by the hydrostatic motor, and a controller for receiving the input signal and a signal from the sensor to provide a pressure from the pressure source sufficient to balance pressure at a work port of the motor generated by the wheel driving the motor to stop the movement of the wheel when the input signal indicates the wheel should stop.
A hydrostatic drive circuit for controlling the drive wheels of a vehicle, said drive circuit comprising a drive motor for driving at least one wheel of the vehicle, said drive motor having two work ports, a hydrostatic pump having an output for providing hydraulic fluid under pressure to one work port of the motor, a control for controlling the flow of pressurized hydraulic fluid between the pump and the one motor work port to rotate the motor at a rate which is a function of a control signal, a sensor for sensing rotation of the motor, the motor acting as a pump when driven by rotation of the wheel at a rate greater than a rate provided by the control signal, and said control providing an output of hydraulic fluid under pressure from the pump to the one work port of the motor to counterbalance pressure developed by the motor being driven by the rotation of a drive wheel when an operator input to the control indicates the drive wheels should be at rest.
Dependencies are inferred from the claim text.