JP2004076649A - Energy saving circuit for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy saving circuit for construction machine capable of automatically switching a normal mode and an energy saving mode to an optimum state according to the operation of each attachment. <P>SOLUTION: This circuit has a switch 26 for performing the switching to the normal mode, the energy-saving mode or an automatic mode, and a sensor 25 for detecting a negative control signal. When the negative control signal exceeds a prescribed value in the selection of the automatic mode, the switching to the energy-saving mode is automatically performed to reduce the engine rotating speed so that the fuel consumption and the noise of the engine can be reduced. When the negative control signal is the prescribed value or less, the switching to the normal mode is automatically performed so that the speed of a working machine can be ensured. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an energy-saving circuit for a construction machine, and more particularly, to an energy-saving circuit for a construction machine formed by switching a normal mode, an energy-saving mode, or an automatic mode by operating a switch so that the engine speed can be selected from a high and a low. It concerns the circuit.
[0002]
Problems to be solved by the prior art and the invention
The conventional energy saving circuit of this type of construction machine is capable of selecting the engine speed either high or low by switching between a normal mode and an energy saving mode by a switch operation. In the normal mode, the engine speed is set to a preset high speed (for example, 2000 rpm). On the other hand, in the energy saving mode, the engine speed is set to a preset low speed (for example, 1800 rpm), thereby reducing fuel consumption. It is intended to reduce engine noise.
[0003]
However, when the normal mode is selected by the switch operation, the engine speed is maintained at a high speed even when the engine speed may be lowered, for example, at the time of a boom lowering turn, and the fuel consumption is reduced. There was a problem that worsened.
[0004]
Therefore, in the energy saving circuit of the construction machine controlled to switch between the normal mode and the energy saving mode by the switch operation, the normal mode and the energy saving mode are set according to the operation of each attachment such as raising and lowering the boom and opening and closing the arm. A technical problem to be solved arises in order to enable automatic switching to an optimum state, and the present invention aims to solve this problem.
[0005]
[Means for Solving the Problems]
The present invention has been proposed in order to achieve the above-described object. By switching between a normal mode and an energy saving mode by operating a switch, the engine speed can be selected to be either high or low and an auto mode can be set. When the automatic mode is selected, a signal from a sensor that detects a preset negative control signal when the automatic mode is selected is monitored by the controller, and the optimum mode can be automatically selected from the normal mode or the energy saving mode based on the detection signal of the sensor. Energy-saving circuits for construction machinery,
And, the detection signal of the sensor is guided to the controller, and when the detection signal of the sensor exceeds a predetermined value, the mode is automatically switched to the energy saving mode to lower the engine speed to a low speed, On the other hand, when the detection signal of the sensor is equal to or less than a predetermined value set in advance, an energy saving circuit for a construction machine is provided which automatically switches to a normal mode to increase the engine speed. .
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an attachment control circuit of a hydraulic shovel as an example of an energy saving circuit. The discharge oil of a variable displacement type hydraulic pump 11 includes a control valve 12 for a boom, a control valve 13 for an arm, and a control valve 14 for a bucket. It returns to the tank 15 by bypass. The negative control pressure generated by the negative control throttle 16 acts on the regulator 17 through the negative control oil passage 21 to change the tilt angle of the hydraulic pump 11 to adjust the discharge amount.
[0007]
The spools of the control valves 12, 13, and 14 are switched by operating the levers of the remote control valves 18, 19, and 20, respectively, so that a boom raising / lowering operation, an arm opening / closing operation, and a bucket opening / closing operation are performed.
[0008]
Further, a sensor 25 is provided in the negative control oil passage 21 to detect a negative control signal, and the negative control signal is input to the controller 30. Reference numeral 26 denotes a switch for switching between a normal mode, an energy saving mode, and an auto mode. Reference numeral 27 denotes an engine throttle governor. As will be described later, the rack position of the engine throttle governor 27 changes according to a command signal from the controller 30, and the engine speed is set to a preset high speed, or , Or low rotation.
[0009]
FIG. 2 is a flowchart for explaining the operation of the energy saving circuit. First, the controller 30 determines the position (normal, energy saving, or automatic) of the mode switching switch 26 (step 1).
[0010]
In the case of the energy saving mode, a control signal is output to maintain the engine speed at a preset low speed (for example, 1800 rpm) (step 2). On the other hand, in the normal mode, a control signal is output to maintain the engine speed at a preset high speed (for example, 2000 rpm). (Step 3).
[0011]
In the case of the auto mode, the controller 30 determines whether or not the negative control signal is equal to or less than a predetermined value based on the detection signal from the sensor 25 (step 4).
[0012]
When a boom raising operation, an arm opening / closing operation, or the like is performed, the negative control pressure decreases. Therefore, when the detected negative control pressure is equal to or lower than a predetermined value (for example, 0.5 MPa), the lever operation amount becomes approximately 70 to 80%. Therefore, a control signal is output from the controller 30 to the engine throttle governor 27 so as to maintain the engine speed at a preset high speed (for example, 2000 rpm) (step 4 → step 3).
[0013]
On the other hand, if the detected negative control pressure exceeds the predetermined value (here, 0.5 MPa) in step 4, the mode automatically switches to the energy saving mode (step 4 → step 2), and the engine speed decreases. Then, control is performed so as to reduce fuel consumption and noise.
[0014]
Therefore, for example, when the switch 26 is in the normal mode during the boom lowering operation, the engine speed is conventionally kept at a high speed, but when the auto mode of the present invention is selected, the bleeding is performed during the boom lowering operation. Since it is off, the negative control pressure does not drop to 0.5 MPa, so that the mode is automatically switched to the energy saving mode, and control can be performed so as to lower the engine speed to low speed.
[0015]
When the boom is raised, the arm is opened and closed, and the bucket is opened and closed, the negative control pressure becomes 0.5 MPa or less near the lever full stroke, and the engine speed is switched to a high speed. There is no lack of horsepower or sluggishness during work or lifting and turning work. In addition, when the lever operation is not performed or the negative control pressure exceeds a predetermined value due to the operation with the half lever, the engine speed can be automatically reduced to save energy.
[0016]
Therefore, the present invention can be variously modified without departing from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.
[0017]
【The invention's effect】
As described in detail in the above embodiment, the present invention detects a negative control signal set in advance when an automatic mode is selected in a construction machine in which a normal mode, an energy saving mode or an automatic mode can be switched by a switch operation. When the detection signal from the sensor exceeds a predetermined value, the system automatically switches to the energy saving mode and lowers the engine speed to a low speed. It is possible to save energy even when it is off.
[Brief description of the drawings]
The figure shows an embodiment of the present invention.
FIG. 1 is an attachment control circuit diagram of a hydraulic shovel as an example of an energy saving circuit.
FIG. 2 is a flowchart illustrating the operation of an energy saving circuit.
[Explanation of symbols]
25 Sensor (for detecting a negative control signal) 26 Switch (for switching modes) 27 Engine throttle governor 30 Controller

Claims (2)

By switching between a normal mode and an energy saving mode by a switch operation, the sensor is configured to be able to select the engine speed either high or low, set an auto mode, and detect a preset negative control signal when the auto mode is selected. A signal from the controller is monitored by a controller, and an optimum mode can be automatically selected from a normal mode and an energy saving mode based on a detection signal of the sensor. The detection signal of the sensor is guided to a controller, and when the detection signal of the sensor exceeds a predetermined value, the mode is automatically switched to the energy saving mode to lower the engine speed to a low speed. 2. The energy-saving circuit for a construction machine according to claim 1, wherein when the detection signal of the sensor is equal to or less than a predetermined value, the mode is automatically switched to a normal mode to increase the engine speed.

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