HYDROSTATIC TRANSMISSION CONTROL SYSTEM HAVING AGGRESSIVE AND NON-AGGRESSIVE MODES

摘要

A control system for a utility vehicle transmission provides for operatorselection of vehicle "aggressiveness," or rates of acceleration in response tooperator command. The aggressiveness of a vehicle's performance can becontrolled by modulating control signals to proportional control valves, whichdetermine the transmission acceleration, according to two or more electricalramp-up (or ramp-down) profiles, in response to an operator's accelerationcommand (or deceleration command). The transmission control systemincludes a controller, directional switches and electro-hydraulic valves whichcontrol hydraulic pressure in the servo control system of a hydrostatictransmission. The operator is provided with a two-position set switch. Withthe set switch in the less aggressive position, in response to an operator'scommand, the software in the controller provides a relatively slow currentramp to energize the control valves. With the switch in the more aggressiveposition, the current ramps and resultant pressure ramps are faster, thuscausing more aggressive transmission operation for the hydrostatictransmission.