JPS6248083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a hydraulic system of a hydraulic construction machine.

[Conventional technology]

FIG. 1 is a diagram showing a control device to which a method for controlling a hydraulic system of a hydraulic construction machine is applied. In the figure, 22 is an engine, 23 is a fuel injection pump for the engine 22, 24 is a fuel injection pump control device, 2
5 is a rotation speed detector of the engine 22, 26 is a variable displacement hydraulic pump driven by the engine 22, 27 is a regulator of the hydraulic pump 26, 28
29 is a directional switching valve provided between the hydraulic pump 26 and the actuator 28, and 30 is a plurality of operations provided corresponding to the actuator 28. The operating lever 30 operates the regulator 27 and the directional switching valve 29 to instruct the actuator 28 to operate. 31 is a control device, 31a is an operating lever 30, and a rotation speed detector 25
31b is an A/D that converts the analog signal from multiplexer 31a into a digital signal.
A converter, 31c, is a memory circuit that stores processing procedures for the regulator 27, directional control valve 29, delay time counting procedures, etc., and 31d, a signal from the A/D converter 31b, according to the processing order stored in the memory circuit 31c. The output circuit 31e is a control circuit that controls the output circuit 31e based on the above, and the output circuit 31e controls the regulator 27 and the direction switching valve 29. 32 is a throttle lever that sets the rotation speed of the engine 22, and 34 is a low-speed operation control that lowers the rotation speed of the engine 22 when the actuator 28 is not operated in order to control the rotation speed of the engine 22 and reduce fuel consumption. a changeover switch 33 for switching between a state in which low-speed operation control is performed and a state in which low-speed operation control is not performed;
1e, a fuel injection amount control device that inputs a signal from the changeover switch 34 and outputs a signal to the fuel injection pump control device 24;

In this control device, when the control lever 30 is operated, an output signal corresponding to the amount of operation is output from the control lever 30, and the output signal is sent to the control device 31.
from the control device 31 to the regulator 2.
7. A control signal corresponding to the output signal of the operating lever 30 is output to the directional switching valve 29, and the tilting direction and tilting angle of the hydraulic pump 26 and the switching direction and switching amount of the directional switching valve 29 are controlled according to the control signal. is controlled, so the amount of pressure oil supplied to the actuator 28 becomes a value that corresponds to the output signal of the operating lever 30, and the speed of the actuator 28 becomes a value that corresponds to the amount of pressure oil that is supplied to the actuator 28. The speed of the actuator 28 is controlled according to the amount of operation of the operating lever 30. In addition, the fuel injection amount control device 33
Signals from the rotation speed detector 25, output circuit 31e, throttle lever 32, and changeover switch 34 are input to the engine, and the fuel injection pump control device 24 is controlled by the signal from the fuel injection amount control device 33.
The fuel injection amount of the fuel injection pump 23 has a value according to the signal from the fuel injection amount control device 33, and the rotation speed of the engine 22 is ultimately controlled by the signal from the fuel injection amount control device 33.

Next, a method of controlling the hydraulic system of a conventional hydraulic construction machine using the control device shown in FIG. 1 will be explained with reference to FIG. First, changeover switch 34
When the low-speed operation control is not performed by the operation, the rotation speed of the engine 22 is set to a value corresponding to the operation amount of the throttle lever 32 by repeating A→D, regardless of the operation state of the operation lever 30. The engine 22 is commanded to operate at the set rotation speed, and the engine 22 rotates at the set rotation speed. In this state, if the changeover switch 34 is changed to perform low-speed operation control, the operating lever 34
When all of 0 are in the neutral state, by repeating A→B→C, a low speed operation is commanded to set the engine 22 rotation speed to a low speed lower than the set rotation speed, and the engine 22 is operated at a low speed rotation speed. be done. In this state, when at least one of the operating levers 30 is activated, the set rotation speed operation is commanded by repeating A→B→D, and the engine 22 is operated at the set rotation speed. In this state, when all the operating levers 30 are set to the neutral state, A→
By repeating B→C, low speed rotation speed operation is commanded, and the engine 22 is operated at low speed rotation speed. Therefore, when the actuator 28 is not operating, such as during a short break in work, the rotational speed of the engine 22 is reduced, so fuel consumption can be reduced.

[Problem that the invention seeks to solve]

However, when the operating lever 30 is operated as shown in FIG. 3a, the rotational speed of the engine 22, the tilt angle of the hydraulic pump 26, and the discharge flow rate of the hydraulic pump 26 are as shown by the broken lines in FIG. 3b to d. Changes to
That is, when all the operating levers 30 are in the neutral state and the engine 22 is at a low rotational speed, when at least one of the operating levers 30 is activated, the state shown in FIG. As shown by the broken line, when the operating lever 30 is operated, the tilting angle of the hydraulic pump 26 changes to the operating lever 3.
However, since the torque of the hydraulic pump 26 is proportional to the product of the discharge pressure of the hydraulic pump 26 and the tilting angle of the hydraulic pump 26, the torque acting on the engine 22 increases as the amount of operation of the hydraulic pump 26 increases. Since the discharge pressure of 26 increases as the tilt angle increases,
Since the engine 22 increases its rotational speed while driving the load, the rise in the rotational speed of the engine 22 is significantly delayed, as shown by the broken line in FIG. 3b. The discharge flow rate of the hydraulic pump 26 is proportional to the product of the tilt angle of the hydraulic pump 26 and the rotation speed of the hydraulic pump 26, and the rotation speed of the hydraulic pump 26 is proportional to the rotation speed of the engine 22. If the rise in the rotation speed of the hydraulic pump 2 is significantly delayed, as shown by the broken line in Fig. 3d, the hydraulic pump 2
Since the discharge flow rate of the hydraulic pump 26 increases slowly, the speed of the actuator 28 increases slowly. Since the speed of the actuator 28 becomes a value corresponding to the amount of operation of the operating lever 30, the operability is hindered.

This invention was made to solve the above-mentioned problems, and can reduce fuel consumption.
Moreover, it is an object of the present invention to provide a method for controlling the hydraulic system of a hydraulic construction machine with good operability.

[Means for solving problems]

In order to achieve this objective, the present invention includes an engine, a variable displacement hydraulic pump driven by the engine, a plurality of actuators operated by pressure oil from the hydraulic pump, and a set rotation speed of the engine. A hydraulic system for a hydraulic construction machine, comprising: a throttle lever for controlling the hydraulic pump; a regulator for the hydraulic pump; and a plurality of operation levers that are provided corresponding to the actuator and that operate at least the regulator to command the operation of the actuator. In the method of controlling
When at least one of the operating levers is activated, a set rotation speed operation is commanded to set the engine rotation speed to the set rotation speed set by the throttle lever, and the set rotation speed operation command is When all of the control levers are in the neutral state, the engine is commanded to operate at a low speed lower than the set rotation speed, and the low speed operation command is When at least one of the operating levers is activated in a state in which the engine is being operated, the regulator is held in an unloaded state until the number of revolutions of the engine reaches a predetermined control number of revolutions.

[Effect]

In this method of controlling the hydraulic system of a hydraulic construction machine, low-speed engine speed operation is commanded when all the operating levers are in the neutral state, so the engine speed becomes low speed during a short break in work. Additionally, when at least one of the control levers is activated while a low-speed engine speed operation command is issued, the regulator is held in an unloaded state until the engine speed reaches a predetermined control speed. , the engine accelerates with almost no load.

〔Example〕

Next, a method for controlling the hydraulic system according to the present invention in the control device shown in FIG. 1 will be explained with reference to FIG. 4. First, when the changeover switch 34 is operated to disable low-speed operation control, the operation lever 30 is turned off by repeating A→G→D.
Operation at the set rotation speed is commanded regardless of the operating state of the regulator 27, while the regulator 27 is in an on-road state, that is, when the operating lever 30 is operated, the regulator 27 is activated and the tilt angle of the hydraulic pump 26 is adjusted to the operating amount of the operating lever 30. The state will be such that the value corresponds to . In this state, when the changeover switch 34 is switched to perform low-speed operation control, when all the operating levers 30 are in the neutral state, A→B
By repeating →C, low speed rotation speed operation is commanded, and the engine 22 is operated at low speed rotation speed. In this state, when at least one of the operating levers 30 is activated, the regulator 27 is placed in the unloaded state by repeating A→B→E→F→D until the engine 22 rotation speed reaches the control rotation speed. ,
In other words, even if the control lever 30 is operated, the regulator 27 does not operate, and the regulator 27 maintains a substantially neutral state so that the tilt angle of the hydraulic pump 26 is kept at the minimum, and the set rotation speed operation is commanded. When the rotational speed of the engine 22 reaches the control rotational speed, the regulator 27 is brought into an on-road state by repeating A→B→E→G→D, and the engine 22 continues to operate at the set rotational speed. In this state, when all the operating levers 30 are set to the neutral state, low-speed rotational speed operation is commanded by repeating A→B→C, and the engine 22
is operated at low speed.

When controlling in this way, the operating lever 30
When operated as shown in Figure 3a, engine 2
2, the tilt angle of the hydraulic pump 26, and the discharge flow rate of the hydraulic pump 26 change as shown by solid lines in FIGS. 3b to 3d. That is, when all of the operating levers 30 are in a neutral state and the engine 22 is at a low rotational speed, when at least one of the operating levers 30 is activated, the engine 22's rotational speed becomes low. The regulator 27 maintains the unloaded state until the engine 22 reaches the control rotational speed, for example, the set rotational speed, and when the engine 22 reaches the set rotational speed, the regulator 27 enters the onloaded state. As shown by the solid line in FIG. 3, the tilting angle of the pump 26 increases after the engine 22 rotation speed reaches the set rotation speed, so that the engine 22 rotation speed reaches the set rotation speed, as shown by the solid line in FIG. The discharge flow rate of the hydraulic pump 26 is almost zero until the number reaches 1, and the engine 22 increases the rotation speed with almost no load.
As shown by the solid line, the rotational speed of the engine 22 rises extremely quickly. Therefore, even if the tilting angle of the hydraulic pump 26 increases after the rotation speed of the engine 22 reaches the set rotation speed, as shown by the solid line in FIG. 3 c, as shown by the solid line in FIG. To,
Since the discharge flow rate of the hydraulic pump 26 increases according to the tilt angle of the hydraulic pump 26, after a short period of time has elapsed from the time when the operating lever 30 is operated, the discharge flow rate of the hydraulic pump 26 increases depending on the operating amount of the operating lever 30. Since the speed of the actuator 28 becomes a value corresponding to the amount of operation of the operating lever 30,
Very easy to operate.

Next, another hydraulic system control method according to the present invention in the control device shown in FIG. 1 will be described with reference to FIG. 5. First, when the changeover switch 34 is operated to disable low-speed operation control, by repeating A→G→D, the regulator 27 enters the on-road state regardless of the operating state of the operating lever 30, and the set rotation speed Driving is ordered. In this state, when the changeover switch 34 is switched to perform low-speed operation control, and all the operating levers 30 are in the neutral state, the operation will continue until the preset delay time elapses.
By repeating A→B→H→I→G→D, the engine 22 continues to be operated at the set rotation speed, and when the delay time has elapsed from the time the changeover switch 34 was switched, A→B→H→I→C As a result, low speed rotation speed operation is commanded, and then by repeating A→B→H→C, the engine 22 is operated at low speed rotation speed.
In this state, when at least one of the control levers 30 is activated, the rotation speed of the engine 22 is A→B→J→E→F→D until the rotation speed of the engine 22 reaches the control rotation speed.
By repeating this, the regulator 27 is held in the unloaded state, and the set rotation speed operation is commanded. When the rotation speed of the engine 22 reaches the control rotation speed, by repeating A→B→J→E→G→D, ,
The regulator 27 is brought into an on-road state, and the engine 22 continues to operate at the set rotation speed. In this state, when all the operating levers 30 are set to the neutral state, A→B→H until the delay time elapses.
By repeating →I→G→D, the engine 22 continues to operate at the set rotation speed. In this case, the regulator 27 is in the on-road state, but the operating lever 3
Since all 0s are in the neutral state, regulator 2
7 is almost neutral. And operation lever 3
When the delay time elapses from the time when all zeros are in the neutral state, low speed rotational speed operation is commanded by A→B→H→I→C, and then by repeating A→B→H→C, the engine 22 is operated at low speed. In this state, when at least one of the control levers 30 is activated, as described above, until the rotation speed of the engine 22 reaches the control rotation speed,
The regulator 27 is held in an unloaded state, and when the number of revolutions of the engine 22 reaches the control number of revolutions, the regulator 27 is brought into an on-road state. Furthermore, when all of the operating levers 30 are set to the neutral state while at least one of the operating levers 30 is in the operating state, as described above, until the delay time elapses, the A→B→H→I →G→D
By repeating this, the engine 22 continues to operate at the set rotation speed and the regulator 27 is maintained in the on-road state, but in this state, that is, before the delay time elapses, at least one of the operating levers 30 becomes activated. Sometimes A→B→J→
By repeating E→G→D, the engine 22 continues to operate at the set rotation speed, and the regulator 2
7 is kept on-load.

By the way, when controlling as shown in FIG. 2, if the operating lever 30 is operated as shown in FIG. 6a, the rotation speed of the engine 22 and the hydraulic pump 26
The tilting angle of and the discharge flow rate of the hydraulic pump 26 are as shown in Fig. 6b.
~d changes as shown by the broken line. That is, when at least one of the operating levers 30 is in the operating state and the rotational speed of the engine 22 is at the set rotational speed, when all of the operating levers 30 are in the neutral state, the broken line in FIG. 6b As shown in FIG. 6, the rotation speed of the engine 22 decreases as soon as the operating lever 30 is operated, and as shown by the broken line in FIG. becomes smaller, so Figure 6 d
As shown by the broken line, the discharge flow rate of the hydraulic pump 26 decreases at the same time as the operating lever 30 is operated. In this state, when at least one of the operating levers 30 is operated, as shown by the broken line in FIG. 6c,
As the operating lever 30 is operated, the tilting angle of the hydraulic pump 26 increases, so the engine 22 increases its rotational speed while driving the load, as shown by the broken line in FIG. 6b. , engine 2
2, the rise in rotational speed is significantly delayed. Therefore, as shown by the broken line in FIG. 6d, the hydraulic pump 2
Since the discharge flow rate of 6 gradually increases, the speed of the actuator 28 increases slowly.
Since the value corresponds to the operation amount of 0, operability is hindered. On the other hand, when controlling as shown in FIG. 5, if the operating lever 30 is operated as shown in FIG. The flow rate changes as shown by the solid lines in FIGS. 6b to 6d. That is, with at least one of the operating levers 30 in the operating state and the engine 22 rotational speed reaching the set rotational speed, all of the operating levers 30 are brought into the neutral state, and further, before the delay time elapses. When at least one of the operating levers 30 is activated, the regulator 27 is held in the on-load state, so that the hydraulic pump 26 is activated at the same time as the operating lever 30 is operated, as shown by the solid line in FIG. 6c. The tilt angle of is increased, and the angle of inclination of
Since the rotational speed of the engine 22 is maintained at the set rotational speed as shown by the solid line in FIG. value, hydraulic pump 2
Since the discharge flow rate of the hydraulic pump 26 increases rapidly, the discharge flow rate of the hydraulic pump 26 increases quickly after a short period of time from the time when the operation lever 30 is operated.
actuator 2.
Since the speed of No. 8 corresponds to the amount of operation of the operating lever 30, the operability is very good.

In this way, in the control method explained with reference to FIG. 5, when the delay time has elapsed from the time when all the operating levers 30 are in the neutral state, low speed rotational speed operation is commanded. Since the rotation speed of the engine 22 becomes a low rotation speed, fuel consumption can be reduced, and when at least one of the control levers 30 is activated in this state, the rotation speed of the engine 22 becomes the control rotation speed. Since the regulator 27 is held in an unloaded state until reaching
The discharge flow rate of 6 increases rapidly, and the operation lever 30
After a short period of time has elapsed since the time when the hydraulic pump 26 was operated, the discharge flow rate of the hydraulic pump 26 becomes a value corresponding to the operating amount of the operating lever 30, and the speed of the actuator 28 becomes a value corresponding to the operating amount of the operating lever 30. Therefore, operability is not impaired. This is the fourth
Although the control method is equivalent to the control method explained in the figure, in the control method explained in FIG. If at least one of the levers 30 is activated, the rotation speed of the engine 22 will not decrease, so the discharge flow rate of the hydraulic pump 26 will increase immediately, and a short time will elapse from the time when the operating lever 30 is operated. After that, the discharge flow rate of the hydraulic pump 26 becomes a value corresponding to the amount of operation of the operating lever 30, and the speed of the actuator 28 changes to a value corresponding to the operating amount of the operating lever 30.
Since the value corresponds to the amount of operation, operability is not impaired.

In the above-mentioned embodiment, the control rotation speed is set to the set rotation speed, that is, when all the control levers 30 are in the neutral state and at least one of the control levers 30 is activated, the engine Although the regulator 27 is put into the on-load state when the rotation speed of the motor 22 reaches the set rotation speed, the control rotation speed may be set to a predetermined value smaller than the set rotation speed. In this case, the operating lever 3
0 is operated as shown in FIG. 3a, the rotational speed of the engine 22, the tilt angle of the hydraulic pump 26, and the discharge flow rate of the hydraulic pump 26 change as shown by the dashed lines in FIGS. 3b to 3d. That is, as shown by the dashed line in FIG. 3c, when the rotational speed of the engine 22 reaches the control rotational speed, the tilting angle of the hydraulic pump 26 increases, and therefore, as shown by the dashed dotted line in FIG. After the rotation speed of the engine 22 reaches the control rotation speed, the engine 22 increases the rotation speed while driving the load, and the rise in the rotation speed of the engine 22 is delayed. As shown by the dashed line in d, the discharge flow rate of the hydraulic pump 26 increases rapidly until the rotation speed of the engine 22 reaches the control rotation speed, and after the rotation speed of the engine 22 reaches the control rotation speed, The discharge flow rate of the hydraulic pump 26 gradually increases, but unlike the conventional case, when the operating lever 30 is operated, the tilting angle of the hydraulic pump 26 increases in accordance with the increase in the operating amount of the operating lever 30. In comparison, the discharge flow rate of the hydraulic pump 26 becomes a value corresponding to the operating amount of the operating lever 30 in a very short time, and the speed of the actuator 28 becomes a value corresponding to the operating amount of the operating lever 30, resulting in improved operability. will not be harmed. In this way, the control rotation speed can be arbitrarily determined between the low speed rotation speed and the set rotation speed. Further, in the above embodiment, a method of controlling the hydraulic system in which the regulator 27 and the directional control valve 29 of the variable displacement hydraulic pump 26 are operated by the operating lever 30 has been described. It is clear that the present invention can also be applied to a method of controlling a hydraulic system in which a pump and an actuator constitute a closed circuit, that is, a hydraulic system in which only the regulator of a variable displacement hydraulic pump is operated by the operating lever 30. In other words, the discharge flow rate of the hydraulic pump has a value corresponding to the rotation speed of the engine 22, so if the rise of the rotation speed of the engine 22 is delayed, the discharge flow rate of the hydraulic pump will gradually increase accordingly, and the speed of the actuator 28 will increase. This is because the value does not correspond to the amount of operation of the operating lever 30, which impairs operability.

〔Effect of the invention〕

As explained above, in the method for controlling the hydraulic system of a hydraulic construction machine according to the present invention, low-speed rotational speed operation is commanded when all the operating levers are in the neutral state, so that the engine speed is increased during short breaks in work. Since the number of engine rotations becomes low, it is possible to reduce fuel consumption, and when at least one of the control levers is activated while a low-speed rotation speed operation command is issued, the engine rotation speed becomes lower. Since the regulator is held in an unloaded state until the control speed is reached, the engine accelerates with almost no load, so the engine speed rises very quickly at the start of operation, which reduces the hydraulic pump's discharge. When the flow rate increases rapidly and a short time has elapsed from the time when at least one of the operating levers is operated, the speed of the actuator becomes a value that corresponds to the amount of operation of the operating lever, so the operability is greatly improved. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a control device for a hydraulic system of a hydraulic construction machine, Fig. 2 is a flowchart for explaining a conventional method of controlling a hydraulic system, and Fig. 3 is a diagram showing a control device for a hydraulic system shown in Fig. 1. Graphs for explaining the operation, FIGS. 4 and 5 are flowcharts for explaining the control method of the hydraulic system according to the present invention, and FIG. 6 is for explaining the operation of the control device shown in FIG. 1. This is a graph for 22...Engine, 23...Fuel injection pump, 24
... fuel injection pump control device, 25 ... rotation speed detector, 26 ... variable displacement hydraulic pump, 27 ... regulator, 28 ... actuator, 29 ... directional switching valve, 30 ... operation lever, 31 ... control device, 32 ...
Throttle lever, 33...Fuel injection amount control device,
34...Selector switch.

Claims (1)

[Claims] 1 An engine, a variable displacement hydraulic pump driven by the engine, a plurality of actuators operated by pressure oil from the hydraulic pump, a throttle lever for setting the rotation speed of the engine, and a regulator for the hydraulic pump. and a plurality of operating levers provided corresponding to the actuator and for operating at least the regulator to command the operation of the actuator, a method for controlling a hydraulic system of a hydraulic construction machine,
When at least one of the operating levers is activated, a set rotation speed operation is commanded to set the engine rotation speed to the set rotation speed set by the throttle lever, and the set rotation speed operation command is When all of the control levers are in the neutral state, the engine is commanded to operate at a low speed lower than the set rotation speed, and the low speed operation command is When at least one of the operating levers is activated in a state in which the control lever is operated, the hydraulic pressure maintains the regulator in an unloaded state until the rotational speed of the engine reaches a predetermined control rotational speed. A method for controlling the hydraulic system of type construction machinery.