Deere & Company

Scott Allen Toppin

Mark Allen Bergene

Sanjay Ishvarlal Mistry

Yifei Raymond Hou

A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. The steering motor provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel and drives left and right tracks to turn the vehicle. The control system includes a control unit which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, and the steering control signals. The control unit, when the steering control signals indicate that the steering wheel is turned in a direction opposite to a direction of rotation of the steering motor, generating and saving a first ratio value representing a ratio of the motor speed to the pump speed. Then, if the steering control signal is unchanged after a certain time duration, the control unit generates and saves a second ratio value representing a later ratio of the motor speed to the pump speed. The control unit then calculates a difference value representing a difference between the first and second ratio values, and generates a fault signal if the difference value has a magnitude which is less than a predetermined magnitude. Thus, the control system generates a fault signal when the sensed signals indicate that the steering pump swashplate position is not changing as it should in response to changes in steering wheel position.

Tracked vehicle steering system with failure detection

A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. The steering motor provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel and drives left and right tracks to turn the vehicle. The control system includes a control unit which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, and the steering control signals. The control unit calculates a motor speed threshold value as a function of sensed engine speed and steering control signals, and generates a fault signal as a function of a relationship between the steering motor speed signal and a motor speed threshold value. The control unit generates an overspeed fault signal when the steering motor speed signal is greater than the motor speed threshold value or less than a negative motor speed threshold value, and generates a data conflict fault signal when the steering motor speed signal is less than a negative minimum motor speed threshold value or greater than a minimum motor speed threshold value. The control unit, when the vehicle is not being commanded to turn by the steering control signals, generates a minimum threshold value, and generates an overspeed fault signal when the motor speed signal is greater than the minimum threshold value or is less than a negative minimum threshold value.

Growing community of inventors

Cedar Falls, IA, United States of America

Scott Allen Toppin