Variable Pressure Limiting for Variable Displacement Pumps

摘要

Method of controlling multiple variable displacement hydraulic pumps determined relative to operator commands. If non-second-pump-dominated command, a respective adjusted displacement request is determined based upon the lesser of the operator requested torque limited displacement and an adjusted torque limited displacement that calculated based upon and the torque limited displacement of the respective pump and a scaling factor calculated based upon the first relief valve set pressure and respective pump pressure. If second-pump-dominated command, the set pressure of a relief valve associated with one of the pumps is instead utilized in calculating the scaling factor in the above strategy.

主权项

1. In a machine having moveable ground engaging members, a hydraulic system having at least one pump, and at least first and second relief valves, the second relief valve being associated with the at least one pump, wherein the pump is a variable displacement hydraulic pump, a method of controlling operation of the pump implemented by a programmable controller, the method comprising:
receiving an operator request for operation of the machine, determining if the operator request of the pumps includes a dominant command associated with operation of the pump, determining a minimum of the operator requested torque limited displacement of the pump and an adjusted torque limited displacement for the pump, wherein
if the operator request includes the dominant command associated with operation of the pump, calculating the adjusted torque limited displacement for the pump using a pump torque limited displacement and a scaling factor based upon a current pressure at the pump and a pressure setting at the second relief valve,if the operator request does not include the dominant command associated with operation of the pump, calculating the adjusted torque limited displacement for the pump using a pump torque limited displacement and a scaling factor based upon a current pressure at the pump and a pressure setting at the first relief valve, and setting the minimum of the operator requested torque limited displacement of the pump and the adjusted torque limited displacement for the pump as a final adjusted displacement pump request.