Method and apparatus for controlling multiple variable displacement hydraulic pumps

Abstract

A method and apparatus for controlling discharge pressure and pump displacement of a plurality of variable displacement hydraulic pumps (102, 103) having connected discharge ports (206) is provided. Each pump (102, 103) includes a swashplate (104) and a control valve (302) for controlling an angle of inclination of the swashplate. A desired first pump displacement control law is determined for a first pump (102) and determined a desired second pump discharge pressure control law for a second pump (103). The first control law is used to determine a first intermediate control variable. The second control law is used to determine a second intermediate control variable. The control of the first and second pumps (102, 103) are combined using the first and second intermediate control variables.; A desired first control valve setting for the control valve (302) of the first pump is determined using the combined first and second intermediate control variables and the first control law. A desired second control valve setting for the control valve (302) of the second pump is determined using the combined first and second intermediate control variables and the second control law.

Description

technical field [0001] The present invention relates generally to variable displacement hydraulic pumps, and more particularly to methods and apparatus for controlling a plurality of variable displacement hydraulic pumps. Background technique [0002] Variable displacement hydraulic pumps are used in a variety of applications. For example, hydraulic construction machines, earth moving machines, and the like often use variable displacement hydraulic pumps to provide the flow of pressurized hydraulic fluid needed to perform a desired work function. Pump operation may be affected by changes in pressure and flow output caused by changes in load demand. It has long been desired to maintain the pressure output of the pump in a consistent manner so that the operation of the hydraulic system is well behaved and predictable. Therefore, attempts have been made to monitor the pressure output of the pump and control the operation of the pump accordingly to compensate for changes in lo...

AI Technical Summary

Problems solved by technology

However, since the discharge ports of the two pumps are connected, any change in the displacement of one pump will necessarily affect the other pump.

Therefore, a system that controls both pumps with the same command cannot optimize the efficiency of both pumps

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