JPS6231176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a hydraulic system of a construction machine equipped with a diesel engine, such as a hydraulic shovel or a bulldozer.

FIG. 1 is a diagram showing a device for carrying out a conventional hydraulic system control method. In the figure, 1 is an engine, 2 is a fuel injection pump for the engine 1, 3 is a fuel injection pump control device, 4 is a rotation speed detector that detects the rotation speed of the engine 1, and 5 is at least one engine driven by the engine 1. a load section consisting of two hydraulic pumps, actuators, etc.; 6 an operating lever for instructing the operation of the load section 5; 7 a control device;
7a is an interface that inputs a signal from the operating lever 6 and determines whether it is in the operating state; 7b is a memory circuit that stores a processing procedure; and 7c is a memory circuit that stores a processing procedure stored in the memory circuit 7b. The output circuit 7d is a control circuit that controls the output circuit 7d based on a signal, and the output circuit 7d outputs a low-speed rotation control command signal S, and the signal S is H or L in binary. 8
1 is a throttle lever, 11 is a low speed rotation speed command device, 9 is a switching device that outputs a rotation speed command signal N _R , and when the signal S is H, the switching device 9 outputs a rotation speed command signal N _R1 from the throttle lever 8. The signal N _R
When the signal S is L, the low speed rotation speed command signal N _R0 from the low speed rotation speed command device 11 is output as the signal N _R . Reference numeral 10 denotes a fuel injection amount control device which inputs the signal N _R from the switching device 9 and the signal N _e from the rotation speed detector 4 and outputs a signal to the fuel injection pump control device 3 .

In this device, the load section 5 is controlled by the output signal of the operating lever 6. Furthermore, when any one of the operating levers 6 is in an operating state,
When the signal S becomes H, the signal N _R becomes the signal N _R1 , and when all the operating levers 6 are in the neutral state, the signal S becomes L and the signal N _R becomes the signal N _R0.
becomes. Then, the fuel injection pump control device 3 is controlled by the output signal from the fuel injection amount control device 10, and the fuel injection amount of the fuel injection pump 2 becomes a value corresponding to the signal from the fuel injection amount control device 10. The rotation speed of 1 is a value corresponding to the signal N _R . Therefore, when any one of the operating levers 6 is in the operating state, the rotation speed of the engine 1 is a value corresponding to the signal N _R1 (the operating amount of the throttle lever 8), and all of the operating levers 6 are in the neutral state. When this occurs, the rotational speed of the engine 1 becomes a value corresponding to the signal N _R0 , and low-speed operation control is performed.

Next, the operation in this case will be explained with reference to the flowchart in FIG. First, any one of the operating levers 6
When one is operating the throttle lever 8, the signal S becomes H and the signal N _R becomes the signal N _R1 by repeating A → B, so the rotation speed of the engine 1 is a value corresponding to the amount of operation of the throttle lever 8, i.e. The set rotational speed is reached, and the load section 5 operates appropriately according to the amount of operation of the operating lever 6. Also, set all operating levers 6 to neutral,
When the operation of the load section 5 is interrupted, A
→C→D→A→C, after that A→C is repeated, signal S is set to L, signal N _R is set to signal N _R
0 , and the rotation speed of the engine 1 becomes the low speed setting rotation speed. If at least one operating lever 6 is operated again in this state, A→B is repeated, and the rotation speed of the engine 1 becomes the set rotation speed. That is, when the load section 5 is operating, the rotation speed of the engine 1 is the set rotation speed, and the load section 5 is operated, and when the load section 5 is not operating, the rotation speed of the engine 1 is the low speed set rotation speed, so it is possible to take a short work break. Sometimes fuel consumption can be reduced.

However, in the conventional control method, when all the operating levers 6 are set to neutral, the engine 1
As the rotation speed of the engine suddenly decreases, the driver feels a sudden change in the engine sound, vibrations in the vehicle body, etc., which causes discomfort, causes mental fatigue due to the unnaturalness, and even seriously impairs operability. You will lose money.

This invention was made to solve the above-mentioned problems.
The purpose of the present invention is to provide a method of controlling a hydraulic system in which vibrations of the vehicle body are not felt.

In order to achieve this object, the present invention provides a method for controlling a hydraulic system having an engine and a load section driven by the engine.
Immediately or after a predetermined period of time has elapsed since all the control levers that command the operation of the load section are in the neutral state, the rotation speed command signal N _R that commands the rotation speed of the engine changes to the low speed rotation speed command signal N _R0 . The rotation speed command signal N is
Subtract the minute change signal △N _R from _R.

FIG. 3 is a diagram showing an apparatus for carrying out the method for controlling a hydraulic system according to the present invention. In the figure, 12 is a control device, 12a is an interface that inputs a signal from the operating lever 6 and determines whether it is in an operating state, 12b is a memory circuit that stores processing procedures, and 12
e is the throttle lever 8 and low speed rotation speed command device 1
A multiplexer 12f sequentially switches and inputs analog signals from 1 and 12e.
12d is an output circuit that outputs the rotation speed command signal N R , and 12c is an output circuit that outputs the rotation speed command signal N _R .
a, a control circuit that controls the output circuit 12d based on the signal from the A/D converter 12f;

Next, a method for controlling a hydraulic system according to the present invention will be explained with reference to the flowchart shown in FIG. First, when any one of the operating levers 6 is operated to operate the load section 5, A→B is repeated, the signal N _R is set to the signal N _R1 , and the rotation speed of the engine 1 is The value corresponds to the amount of operation of the throttle lever 8, that is, the set rotation speed. From this state, when all the operating levers 6 are set to the neutral state and the operation of the load section 5 is paused, A→C→D→A→C→E→D, and thereafter A→C→E→D is repeated. , the signal N _R is set to the value obtained by subtracting the minute change signal ΔN _R from the current signal N _R , and when the signal N _R reaches the signal N _R0 , A→
C → E → F is repeated, and the signal N _R becomes the signal N _R0
is set to Here, from "beginning" to "beginning"
Since the processes up to this point are repeated at almost constant intervals, the signal N _R gradually decreases from the time when all the control levers 6 are set to the neutral state, from the signal N _R1 to the signal N _R0 , so that the rotation speed of the engine 1 is set. The rotation speed gradually decreases from low to low rotation speed. Next, when at least one of the operating levers 6 is operated, A→B is repeated, the signal N _R is immediately set to the signal N _R1 , and the rotation speed of the engine 1 is accelerated from the low speed rotation speed to the set rotation speed. Therefore, there is no problem in the operation of the load section 5.

FIG. 5 is a graph showing temporal changes in engine speed, where the broken line shows the case of the conventional method and the solid line shows the case of the method of the present invention.

In the above embodiment, as shown by the solid line in FIG. 6, when all the operating levers 6 are in the neutral position, a certain deceleration is performed from the set rotation speed, but as shown by the broken line in FIG. Thus, the signal ΔN _R may be increased over time to smoothly decrease the engine speed.

In addition, in the above-mentioned embodiment, the engine 1 is started immediately after all the operating levers 6 are in the neutral position.
The rotation speed was gradually reduced to a low rotation speed,
After a predetermined period of time has elapsed since all the operating levers 6 became neutral, the rotational speed of the engine 1 may be gradually reduced to a low rotational speed.

As explained above, in the hydraulic system control method according to the present invention, when all operating levers are set to neutral for a short work break, the engine speed gradually decreases to a low speed. Since the driver does not feel any change in engine sound or vibration of the vehicle body, the driver does not feel uncomfortable, has less mental fatigue, does not impair operability, and can reduce fuel consumption. Also,
If you operate at least one of the control levers even after the engine reaches a low engine speed or when it is in the middle of reaching a low engine speed, the engine speed will immediately reach the set engine speed, so there will be no loss of work efficiency. do not have. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a device for carrying out a conventional hydraulic system control method, FIG. 2 is a flowchart for explaining the operation of the device shown in FIG. 1, and FIG. 3 is a diagram showing a hydraulic system according to the present invention. Figure 4 is a flowchart to explain the operation of the equipment shown in Figure 3. Figures 5 and 6 are diagrams showing the engine speed over time. It is a graph showing changes. 1...Engine, 2...Fuel injection pump, 3...
...Fuel injection pump control device, 5...Load section, 6...
...Operation lever, 7...Control device, 8...Throttle lever, 10...Fuel injection amount control device, 11...
...Low speed rotation speed command device, 12...Control device, 13
...control circuit.

Claims (1)

[Claims] 1. In a method for controlling a hydraulic system having an engine and a load section driven by the engine, immediately or after a predetermined period of time has elapsed from the time when all the operating levers that command the operation of the load section are in the neutral state, The rotation speed command signal N _R that commands the rotation speed of the engine mentioned above is the low speed rotation speed command signal N _R
A control method for a hydraulic system characterized by subtracting a minute change signal ΔN R from the rotation speed command signal N _R at every minute time until the rotation speed command signal N _R becomes _zero .