US 5,481,875 AGranted

Apparatus for changing and controlling volume of hydraulic oil in hydraulic excavator

AssigneeKabushiki Kaisha Komatsu Seisakusho

InventorsFujitoshi Takamura, Yoshinao Haraoka

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Abstract

A hydraulic oil volume change-over control apparatus for a hydraulic excavator subjects a hydraulic pump to load sensing control so as to set an optimum volume of hydraulic oil while an engine for driving the hydraulic pump is operated at a rotational speed at which the fuel consumption of the engine is minimum, by setting a low power mode during breaker work or the like which is performed with a smaller volume of hydraulic oil than that needed during normal excavating work. The control apparatus comprises a variable displacement hydraulic pump, an engine for driving the hydraulic pump, an actuator driven by the hydraulic pump, an actuator control valve disposed in pipe lines between the hydraulic pump and the actuator, a load sensing control device for the hydraulic pump, and a controller for computing a control signal for operating the engine at a minimum fuel consumption rate under a predetermined power designated by the working mode changeover device, so as to deliver the control signal to the load sensing control device and a governor drive device for the engine. The controller can receive signals from a volume sensor for the hydraulic pump, an engine rotational speed sensor for the engine, a hydraulic pressure sensor for the actuator, and the load sensing control device.

Claims16

Dependent claims

A hydraulic oil volume change-over control apparatus for a hydraulic excavator comprising:

a variable displacement hydraulic pump;
an engine for driving said hydraulic pump;
a governor drive device for said engine;
an actuator;
pipe lines connected between said hydraulic pump and said actuator so that said actuator can be driven by said hydraulic pump;
an actuator control valve disposed in said pipe lines between said hydraulic pump and said actuator, and having an upstream side and a downstream side;
a load sensing control device for said hydraulic pump;
a working mode change-over device for establishing a change-over signal representative of the selection for said actuator of one of a low power mode and a high power mode;
a controller receiving said change-over signal from said working mode change-over device, for delivering to said governor drive device an engine fuel injection volume signal, and for delivering to said load sensing control device a load sensing pressure differential signal for changing the volume of said variable displacement hydraulic pump and thereby changing a pressure differential between said upstream and downstream sides of said actuator control valve;
a first engine fuel setting unit;
a first load sensing pressure differential setting unit;
a second engine fuel setting unit;
a second load sensing pressure differential setting unit;
an engine fuel signal generator;
and
a load sensing pressure differential signal generator;
wherein said controller (a) energizes said first engine fuel setting unit and said first load sensing pressure differential setting unit in accordance with a change-over signal from said working mode change-over device representative of the selection of said high power mode so that a first engine fuel setting signal is delivered to said engine fuel signal generator from said first engine fuel setting unit while a first load sensing pressure differential setting signal is delivered to said load sensing pressure differential signal generator from said first load sensing pressure differential setting unit, and (b) energizes said second engine fuel setting unit and said second load sensing pressure differential setting unit in accordance with a change-over signal from said working mode change-over device representative of the selection of said low power mode so that a second engine fuel setting signal is delivered to said engine fuel signal generator from said second engine fuel setting unit while a second load sensing pressure differential setting signal is delivered to said load sensing pressure differential signal generator from said second load sensing pressure differential setting unit, whereby an engine fuel injection volume signal is delivered to said governor drive device for the engine from said engine fuel signal generator while a load sensing pressure differential signal is delivered to said load sensing control device from said load sensing pressure differential signal generator.

14 more elements

A hydraulic oil volume change-over control apparatus for a hydraulic excavator, said apparatus comprising:

a variable displacement hydraulic pump;
an engine for driving said hydraulic pump;
a governor drive device for said engine;
an actuator;
pipe lines connected between said hydraulic pump and said actuator so that said actuator can be driven by said hydraulic pump;
an actuator control valve disposed in said pipe lines between said hydraulic pump and said actuator, and having an upstream side and a downstream side;
a load sensing control device for said hydraulic pump, said load sensing control device having a first pilot cylinder and a second pilot cylinder, said first pilot cylinder being connected to said upstream side of said actuator control valve, said second pilot cylinder being connected to said downstream side of said actuator control valve;
a working mode change-over device for establishing a change-over signal representative of the selection for said actuator of one of a low power mode and a high power mode;
an engine fuel setting unit;
a load sensing pressure differential setting unit;
an engine fuel signal generator;
a load sensing pressure differential signal generator;
means for setting a predetermined engine fuel injection volume for said engine;
means for setting a predetermined load sensing pressure differential for the load sensing control device;
and
a controller receiving said change-over signal from said working mode change-over device, for delivering to said governor drive device an engine fuel injection volume signal, and for delivering to said load sensing control device a load sensing pressure differential signal for changing the volume of said variable displacement hydraULic pump and thereby changing a pressure differential between said upstream and downstream sides of said actuator control valve, wherein said controller either (a) energizes said engine fuel setting unit and said load sensing pressure differential setting unit in accordance with a change-over signal from said working mode change-over device so that a first engine fuel setting signal is delivered to said engine fuel signal generator from said first engine fuel setting unit while a first load sensing pressure differential setting signal is delivered to said load sensing pressure differential signal generator from said first load sensing pressure differential setting unit, or (b) utilizes said means for setting a predetermined engine fuel injection volume for said engine and said means for setting a predetermined load sensing pressure differential for the load sensing control device so that a second engine fuel setting signal is delivered to said engine fuel signal generator from said means for setting a predetermined engine fuel injection volume for said engine while a second load sensing pressure differential setting signal is delivered to said load sensing pressure differential signal generator from said means for setting a predetermined load sensing pressure differential for the load sensing control device, whereby an engine fuel injection volume signal is delivered to said governor drive device for the engine from said engine fuel signal generator while a load sensing pressure differential signal is delivered to said load sensing control device from said load sensing pressure differential signal generator.

13 more elements

A hydraulic oil volume change-over control apparatus for a hydraulic excavator, comprising:

a variable displacement hydraulic pump;
an engine for driving said hydraulic pump;
a governor drive device for said engine;
an actuator;
pipe lines connected between said hydraulic pump and said actuator so that said actuator can be driven by said hydraulic pump;
an actuator control valve disposed in said pipe lines between said hydraulic pump and said actuator, and having an upstream side and a downstream side;
a load sensing control device for said hydraulic pump;
a working mode change-over device for establishing a chanqe-over signal representative of the selection for said actuator of one of a low power mode and a high power mode;
a controller receiving said change-over signal from said working mode change-over device, for delivering to said governor drive device an engine fuel injection volume signal, and for delivering to said load sensing control device a load sensing pressure differential signal for changing the volume of said variable displacement hydraulic pump and thereby changing a pressure differential between said upstream and downstream sides of said actuator control valve;
a volume sensor for said hydraulic pump;
and
a hydraulic pressure sensor for said actuator;
and
wherein said controller utilizes signals from said volume sensor and said hydraulic pressure sensor to compute said load sensing pressure differential signal for operating said engine at a minimum fuel consumption rate under a power designated by said change-over signal from said working mode change-over device.

11 more elements

Dependencies are inferred from the claim text.