US 6,010,309 AGranted

Control device for variable capacity pump

AssigneeKomatsu Ltd.

InventorsFujitoshi Takamura, Seiichi Fuchita, Junichi Tanaka

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Abstract

A controller, for a variable capacity pump, prevents engine stalls due to rapid changes in operating load by increasing the pump absorption torque when the engine speed is high so as to increase the work amount and by reducing the pump absorption torque when the engine speed is low. The controller receives a signal from an engine speed sensor for detecting engine speed. A pump absorption torque curve is pre-set so as to be consecutively stepped with respect to engine speed so as to intersect at an engine rated point. The pump absorption torque is then calculated in accordance with increases or decreases in engine speed. The pump absorption torque is then set to prescribe values based on the results of these calculations and an instruction is outputted to a control valve in such a manner as to regulate a regulator of the variable capacity pump.

Claims4

Dependent claims

Apparatus comprising:

an engine;
a variable capacity pump driven by said engine;
a regulator for controlling a swash plate angle of said variable capacity pump;
an engine speed sensor for detecting engine speed of said engine;
a control valve for regulating a control pressure to said regulator;
a first controller for pre-storing a pump absorption torque curve consecutively increasing and decreasing in steps in accordance with increases and decreases in the speed of said engine, and for outputting a pump absorption torque instruction corresponding to an engine speed signal from said engine speed sensor based on said stored pump absorption torque curve when controlling said variable capacity pump;
and
a second controller for pre-storing a curve of control current values, going to said control valve, corresponding to the pump absorption torque, and for outputting to said control valve a control current value control instruction corresponding to a value of said pump absorption torque instruction from said first controller based on said curve of control current values.

5 more elements

Dependencies are inferred from the claim text.