CONTROL DEVICE FOR HYDROSTATIC TRANSMISSION VEHICLE

摘要

A control device controls a hydrostatic transmission vehicle having a hydrostatic transmission including a variable displacement pump and a variable displacement hydraulic motor. The control device is configured to set a set vehicle speed based on a forward/rearward travel command and a gear stage command instructed by an operator, to set a torque limit usable for the hydrostatic transmission based on an engine speed, to set a vehicle speed limit based on a pressure in the hydraulic circuit and the torque limit, to select a lower one of the set vehicle speed and the vehicle speed limit, and to control respective displacements of the variable displacement pump and the variable displacement hydraulic motor based on the selected vehicle speed.

主权项

1. A control device for a hydrostatic transmission vehicle equipped with a hydrostatic transmission including a variable displacement pump to be driven by an engine and a variable displacement hydraulic motor to be rotated by a pressurized oil from the variable displacement pump, the control device comprising:
a vehicle speed setting section configured to set a set vehicle speed based on both a forward/rearward travel command and a gear stage command instructed by an operator; a hydraulic sensor configured and arranged to detect a pressure in a hydraulic circuit including the variable displacement pump and the variable displacement hydraulic motor; a torque limit setting section configured to obtain an engine speed and set a torque limit usable for the hydrostatic transmission based on the obtained engine speed; a vehicle speed limit setting section configured to set a vehicle speed limit based on the detected pressure in the hydraulic circuit and the torque limit set by the torque limit setting section; a vehicle speed selection section configured to select a lower one of the set vehicle speed set by the vehicle speed setting section and the vehicle speed limit set by the vehicle speed limit setting section; and a pump and motor displacement control section configured to control respective displacements of the variable displacement pump and the variable displacement hydraulic motor based on the vehicle speed selected by the vehicle speed selection section.