US 2013/0152564 A1 · ELECTRONIC HILL HOLD CONTROL OF A HYDROSTATIC TRANSMISSION

Abstract

A hill hold control system and method for a closed loop transmission of a machine is disclosed that includes performing the following steps while the transmission is in neutral: sensing motor shaft movement; and generating fluid flow to offset motor shaft movement and cause substantially zero shaft movement. The method can include comparing a brake timer to a delay value, and activating a brake when the timer exceeds the delay value. The method can include sensing when a brake is applied, and discontinuing the step of generating fluid flow to offset motor shaft movement when a brake is applied. Motor shaft movement can be sensed by sensing rotational speed. Generating fluid flow to offset motor shaft movement can include determining direction and magnitude of fluid flow as a function of the sensed movement; and adjusting the direction and magnitude of fluid flow based on recurring readings of the sensed movement.

Claims20

Dependent claims

A closed loop transmission and hill hold system for a machine, the closed loop transmission and hill hold system comprising:

a pump generating fluid flow;
a motor powered by the fluid flow from the pump;
a fluid leakage path between the motor and the pump;
a motor shaft coupled to the motor, the motor rotating the motor shaft when powered by the fluid flow from the pump and the motor shaft rotating when an external torque is applied to the motor shaft;
a motor shaft sensor detecting movement of the motor shaft;
a neutral sensor detecting when the transmission is commanded to a neutral position, the pump not being commanded by the transmission to generate fluid flow when the transmission is in the neutral position;
wherein when the neutral sensor detects the transmission is in the neutral position, the hill hold system monitors the motor shaft sensor and commands the pump to generate fluid flow in a direction and with a magnitude to cause the motor shaft to be stationary.

4 more elements

Dependencies are inferred from the claim text.

Electronic hill hold control of a hydrostatic transmission

Life of this patent

Electronic hill hold control of a hydrostatic transmission

Life of this patent

Abstract

Claims20