JP2000213005A - Hydraulic circuit for working machine operation of hydraulic excavator - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to improve operability by automatically switching between a speed increase and a normal speed of a specific actuator, and to improve operability in a combined operation of a specific actuator and another actuator. Provided is a hydraulic circuit for operating a work machine of a hydraulic excavator. [Constitution] A second directional control valve (18) connected to a second pump (4) via a merge directional control valve (5), and a second actuator (19) controlled by the second directional control valve (18) And the other operation detecting sensors (21, 22) for detecting that the second actuator (19) has been operated, and when the detection signals of the other operation detecting sensors (21, 22) are not input, the merging switching valve (5 ) Is connected to one pilot line (2) of the first directional control valve (2).
When the command to connect to a) is output to the electromagnetic switching valve (7) and one of the detection signals of the other operation detection sensors (21, 22) is input, only while this detection signal is being input, Merging switching valve
Controller that switches the pilot pressure receiving section (5a) of (5) to the tank (25) and outputs a command to connect to the electromagnetic switching valve (7)
(15) A hydraulic circuit for operating a working machine of a hydraulic excavator, comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for operating a working machine of a hydraulic excavator, and more particularly to a hydraulic circuit for operating a working machine of a hydraulic excavator in which only one operation of a specific working machine can be freely increased. .

[0002]

2. Description of the Related Art In a construction machine such as a hydraulic excavator having a plurality of working machines, it may be required to increase the speed of only a specific working machine according to the work content. Conventionally, a hydraulic circuit having a plurality of hydraulic pumps is configured to meet such demands, and usually, each actuator for operating a plurality of working machines is driven by one hydraulic pump to increase the speed of a specific actuator. Uses a working machine operating hydraulic circuit having a plurality of pumps and driven by another hydraulic pump. For example, FIG. 4 shows a hydraulic circuit for operating a working machine of a hydraulic excavator described in Japanese Patent Application Laid-Open No. 8-134960. Hereinafter, the prior art will be described with reference to FIG. In addition, the corresponding components of the present invention are described in parentheses after each component, and hereinafter, they are indicated by the components of the present invention. A front pump (first pump) 1 is connected to a boom cylinder (first actuator) 3 via a main control valve (first directional switching valve) 2 and
A rear pump (second pump) 4 is connected to one port 3 a of the first actuator 3 via a sub control valve (merging switching valve) 5. Pilot valve (pilot valve) 9
Is composed of an extension pilot valve (pilot valve) 9a and a reduction pilot valve (pilot valve) 9b that are switched based on the operation of a boom operating tool (not shown). The pilot valve 9b is connected to one pilot line 2a of the first directional control valve 2 via a line 8a and a shockless valve 8, and is connected to a pilot valve (pilot valve).
9b is connected to the other pilot line 2b of the first directional control valve 2 via the line 11a and the shockless valve 11. The switching valve (electromagnetic switching valve) 7 is at the position a when the operation changeover switch 6 is OFF, and the operation changeover switch 6 is
At the time of N, the position is switched to the position b. At the position a of the electromagnetic switching valve 7, the pilot valve 9a is connected to the pilot pressure receiving portion 5a of the merging switching valve 5 via the shockless valve 8 and the pilot line 2a. B of the electromagnetic switching valve 7
In the position, one pilot line 2 of the first directional control valve 2
a is connected to a pipe 8a via a bypass circuit G, and the other pilot pipe 2b is connected to a pipe 1 via a bypass circuit H.
1a, and a pilot pressure receiving portion 5a of the merge switching valve 5.
Is connected to the tank 10.

The operation of the above configuration will be described. When performing normal work such as excavation loading work, the work changeover switch 6 is turned off and the electromagnetic switching valve 7 is switched to the position a.
When the pilot valve 9a is operated, the first direction switching valve 2 is switched to the position a and the merge switching valve 5 is switched to the position a by the pilot pressure. For this reason, the discharge oil of the first pump 1 and the second pump 4 is supplied to one port 3 a of the first actuator 3.
And the speed of the extension operation of the first actuator 3 is increased. Since the return oil from the pilot port 2b is drained from the pilot valve 9b while being throttled through the shockless valve 11, the moving speed of the first directional switching valve 2 and the merge switching valve 5 is reduced. When the pilot valve 9b is operated, the pilot pressure causes the first directional control valve 2 to operate.
Is switched to the position b, and the merge switching valve 5 is switched to the position b, so that only the discharge oil of the first pump 1 is supplied to the other port of the first actuator 3, and the first actuator 3 operates to contract at a normal speed. I do. The return oil from the pilot port 2a is drained from the pilot valve 9a while being throttled through the shockless valve 11, so that the moving speed of the first directional control valve 2 is reduced.

When performing a special operation such as driving a pile by vibrating the boom up and down, the operation changeover switch must be turned on.
When the solenoid switch valve 7 is set to the position b and the pilot pressure receiving portion 5a of the merge switch valve 5 is drained, the merge switch valve 5 is connected to the second pump 4 and one port 3 of the first actuator 3.
a. For this reason, since only the pressure oil of the first pump 1 is supplied to one port 3a of the first actuator 3, the speed increasing function of the first actuator 3 does not operate, and the first actuator 3 is operated at the normal speed. Only to extend or contract. The return oil from the pilot pipelines 2a and 2b passes through the bypass circuits G and H, respectively, and is drained from the pilot valves 9a and 9b without being throttled. Therefore, the moving speed of the first directional control valve 2 is reduced. Never.

[0005]

However, the conventional hydraulic circuit for operating a working machine has the following problems. (1) When the work changeover switch 6 is turned off, the first
Since the extension speed of the actuator 3 is increased, at the time of a combined operation with an actuator other than the first actuator 3, it becomes difficult for the operator to work due to an imbalance in the speed between the first actuator 3 and another actuator, and the operation becomes difficult. Is reduced. (2) When the speed of the normal operation such as the excavation loading operation is increased, the return oil of the pilot lines 2a and 2b of the first directional switching valve 2 passes through the shockless valves 8 and 11, respectively. 2 and the moving speed of the merge switching valve 5 are reduced. Therefore, it is not suitable for work in which the work efficiency is improved by increasing the work machine operation speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. The operability is improved by automatically switching the speed increase and the normal speed of a specific actuator, and the specific actuator and other actuators are improved. It is an object of the present invention to provide a hydraulic circuit for operating a working machine of a hydraulic excavator, which can improve the operability in a combined operation with a hydraulic excavator.

[0007]

In order to achieve the above object, a hydraulic circuit for operating a working machine of a hydraulic excavator according to a first aspect of the present invention includes a pilot operation type hydraulic circuit controlled by a first pilot valve. The first pump is connected to the first actuator via a first directional switching valve, and the second pump is connected to a port on one side of the first actuator via a pilot-operated merging switching valve controlled by the first pilot valve. And a pilot line of the first directional switching valve and a pilot pressure receiving portion of the merge switching valve are connected via an electromagnetic switching valve. When connected to the pilot line on one side of the one-way switching valve, the second pump communicates with the port on one side of the first actuator. When the pressure section is drained, in the working machine operating hydraulic circuit of the hydraulic excavator configured to cut off the second pump and the port on one side of the first actuator, the hydraulic pump is connected to the second pump via a merge switching valve. The second directional control valve, the second actuator controlled by the second directional control valve, the other operation detection sensor for detecting that the second actuator has been operated, and not receiving the detection signal of the other operation detection sensor. When the command to connect the pilot pressure receiving portion of the merge switching valve to one of the pilot lines of the first directional switching valve is output to the electromagnetic switching valve, and a detection signal of any of the other operation detection sensors is input, A controller that outputs to the electromagnetic switching valve a command to switch the pilot pressure receiving portion of the merging switching valve to the tank and to connect to the tank only while the detection signal is being input. .

According to the first aspect of the present invention, when one pilot pressure of the first pilot valve is supplied to one pilot line of the first directional control valve, the first directional control valve operates to discharge oil from the first pump. Is supplied to one port of the first actuator. At this time, if the second actuator is not operated and the controller does not input the detection signal of the other operation detection sensor, the electromagnetic switching valve connects the pilot pressure receiving portion of the merge switching valve to one of the pilot lines of the first direction switching valve. Stay connected. Therefore, one pilot pressure of the first pilot valve is supplied to the pilot pressure receiving portion of the merge switching valve, and the discharge oil of the second pump is also supplied to one port of the first actuator. Therefore, since the speed of the first actuator is increased by the discharge oil of the first pump and the second pump, it is not necessary to operate the manual switch at the time of increasing the speed of the first actuator as in the related art. Work efficiency is improved. When the second actuator is operated and the controller inputs the detection signal of the other operation detection sensor while the first actuator is being accelerated by the discharge oil of the first pump and the second pump, the solenoid-operated switching valve switches the merged switching. Connect the pilot pressure receiving part of the valve to the tank. For this reason,
The discharge oil of the second pump is not supplied to one port of the first actuator, and the first actuator is operated by the discharge oil of only the first pump. Therefore, unlike the related art, when returning the increased first actuator to the original speed, it is not necessary to operate the manual switch, and the work operability and work efficiency are improved. When the other pilot pressure of the first pilot valve is supplied to the other pilot line of the first directional control valve, only the discharge oil of the first pump is supplied to the other port of the first actuator regardless of the operation of the second actuator. Is supplied, and the first actuator operates at a normal speed. For this reason, specific first
When the actuator is operated in one direction, the two pumps are joined together to increase the speed, and when the actuator is operated in the other direction, the speed is automatically switched so as to be the normal speed by the one pump. Work efficiency and workability are improved.

A hydraulic circuit for operating a work machine of a hydraulic excavator according to a second invention is provided with the specific operation detection sensor for detecting that the first directional control valve has been operated to one side in the first invention. The controller inputs the detection signal from the specific operation detection sensor and, when the detection signal of the other operation detection sensor is not input, excites the electromagnetic switching valve and changes the pilot pressure receiving portion of the merging switching valve to the first direction switching valve. It is characterized in that it is connected to one pilot line.

According to the second aspect, when the first actuator is operated and the second actuator is not operated, the electromagnetic switching valve is excited to set the pilot pressure receiving portion of the merge switching valve to the first pressure receiving section. Connect to one pilot line of the directional valve. For this reason, the first actuator is the first actuator.
The discharge oil of the pump and the second pump is supplied to increase the speed. At this time, when the second actuator is operated, the electromagnetic switching valve is demagnetized only while the second actuator is operated, and the pilot pressure receiving portion of the merge switching valve is drained. For this reason, the first actuator is supplied with the discharge oil only from the first pump and has a normal speed. As described above, since the electromagnetic switching valve is demagnetized during the combined operation of the first actuator and the second actuator to set the first actuator to the normal speed, the first actuator always becomes the normal speed when the electromagnetic switching valve is not excited due to failure. Since the speed is not increased, work operability is improved.

The hydraulic circuit for operating a working machine of a hydraulic excavator according to a third aspect of the present invention is the hydraulic circuit for operating a work machine according to the first or second aspect, wherein the pressure change per unit time in the pilot pressure receiving portion when the merging switching valve is switched. It is characterized by having a buffer means for reducing the rate.

According to the third aspect, the pressure change rate per unit time in the pilot pressure receiving portion of the merge switching valve is reduced by the buffer means. For this reason, at the time of the normal speed of the first actuator of only the first pump, the first pump and the second pump
The time when the speed of the first actuator is increased due to the merging of the pumps can be changed smoothly. Therefore, the impact of not only the hydraulic device of the hydraulic excavator but also the entire hydraulic excavator is reduced, and the durability is improved. Further, the buffer means for reducing the pressure change rate only reduces the switching speed of the merge switching valve,
Since the switching speed of the first directional control valve is not reduced, the working efficiency does not decrease without a decrease in the operating speed of the work implement.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the same components as those in the conventional technique shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. First, a first embodiment will be described with reference to FIGS. The first pump 1 is connected to the first pump 1 via a pilot-operated first directional control valve 2 controlled by a first pilot valve 9.
Connected to actuator 3. The second pump 4
Is connected to one port 3a of the first actuator 3 via a pilot-operated junction switching valve 5 controlled by a first pilot valve 9. When the electromagnetic switching valve 7 is excited, the pilot pressure receiving portion 5a of the merge switching valve 5 is drained via the position b of the electromagnetic switching valve 7. Solenoid switching valve 7
Is demagnetized, the pilot pressure receiving portion 5a of the merge switching valve 5 is connected to one pilot line 2a of the first direction switching valve 2 via the position a of the electromagnetic switching valve 7. When the pilot pressure is supplied to the pilot pressure receiving portion 5 a of the merge switching valve 5, the second pump 4 communicates with one port 3 a of the first actuator 3 via the position a of the merge switching valve 5. If there is no pilot pressure in the pilot pressure receiving portion 5a of the junction switching valve 5, the connection between the second pump 4 and one port 3a of the first actuator 3 is shut off via the position b of the junction switching valve 5.

Further, a pilot operated second directional control valve 18 controlled by a second pilot valve 17 for operating an actuator other than the first actuator 3 (in this case, a second actuator 19), and a merge switching valve 5 are provided. ,
The second pump 4 and the second actuator 19 are connected. Both pilot lines 18 of the second directional control valve 18
The second pressure sensors 21 and 22 (an example of other operation detection sensors) for detecting that the pilot pressure of the second directional control valve 18 is equal to or higher than a predetermined value are connected to a and 18b, respectively. When the speed-up function setting switch 26 is set to ON, the controller 15
The electromagnetic switching valve 7 is excited only while at least one of the signals 2 is being input, and the pilot pressure receiving portion 5a of the merge switching valve 5 is connected to the tank via the position b of the electromagnetic switching valve 7. In addition, a pipe connecting the pilot pressure receiving portion 5a of the junction switching valve 5 and the electromagnetic switching valve 7 has a throttle (buffer) for reducing the rate of pressure change per unit time in the pilot pressure receiving portion 5a of the junction switching valve 5. An example of means) 23 is interposed. When the speed-up function setting switch 26 is set to OFF,
The controller 15 always excites the electromagnetic switching valve 7 even when the signal of at least one of the second pressure sensors 21 and 22 is input, and switches both the electromagnetic switching valve 7 and the merge switching valve 5 to the position b to increase the number. Disable the speed function. Note that a pilot pump 24 is connected to the first pilot valve 9 and the second pilot valve 17 as a pilot pressure source.

The operation of the embodiment will be described. After setting the speed-up function setting switch 26 to ON, if only the first pilot valve 9 is operated to one side while the second pilot valve 17 is kept in neutral, the controller 15 demagnetizes the electromagnetic switching valve 7 so that the electromagnetic switching valve 7 is demagnetized. The switching valve 7 is at the a position, and the pilot pressure of the first pilot valve 9 is supplied to the pilot pressure 5a of the merging switching valve 5, and the merging switching valve 5 is at the a position. Thereby, the first directional switching valve 2 and the merge switching valve 5 are operated according to the operation of one of the first pilot valves 9, and the first pump 1 and the second pump 2 are connected to one port 3 a of the first actuator 3. The discharge oil of the pump 4 is supplied by merging,
The one-directional speed of the first actuator 3 is increased. Therefore, it is not necessary to manually operate the manual switch when switching between the first actuator 3 and the normal speed as in the prior art, so that work operability and work efficiency are improved.

When the first pilot valve 9 is operated to the other side, the first directional control valve 2 is operated in the other direction (b) in accordance with the operation of the first pilot valve 9 regardless of the operation of the second pilot valve 17.
(The position direction), the discharge oil of only the first pump 1 is supplied to the other port 3b of the first actuator 3, and the first actuator 3 operates at a normal speed.

When the second pilot valve 17 is operated when the speed of the first actuator 3 is increased, the second directional control valve 18 is operated.
Are detected by the second pressure sensors 21 and 22 to be output to the controller 15.
The controller 15 excites the electromagnetic switching valve 7 while the pilot pressure of the second directional switching valve 18 is equal to or higher than a predetermined value, so that the pilot pressure receiving portion 5a of the junction switching valve 5 is drained. As a result, the electromagnetic switching valve 7 is switched to the position b, and the second pump 4 and one port 3a of the first actuator 3 are switched.
And the second direction switching valve 18 is operated according to the pilot pressure of the second pilot valve 17, and the second actuator 19 is operated by the discharge oil of the second pump 4. Thereby, the first actuator 3 operates at a normal speed in both directions only by the discharge oil of the first pump 1, and the second actuator 19 operates at the normal speed by the discharge oil of the second pump 4.

The first actuator 3 is applied to a bucket cylinder, and the two pumps 1
4, when the excavation is started by the combined operation, all the working machines are operated at the normal speed, and when the excavation is completed, the bucket is automatically tilted when the bucket is solely operated to scoop the soil and the like. Since the speed is increased, the amount of scooped soil in the bucket is increased, and the work efficiency is improved. At this time, since the speed increasing function is automatically switched, the operator does not need to perform the switch switching operation, and can concentrate on the operation of the work machine, so that the operability is improved. In this case, since the speed is normal when the bucket is dumped, the scooped soil can be accurately dumped to a target position (eg, a vessel of a dump truck).

Further, the first actuator 3 is applied to an arm cylinder, and in pulling work and slope adjustment work, etc., the pulling side works slowly and carefully with the discharge amount of one pump to improve the working accuracy and return. The work efficiency can be improved by quickly returning the side with the discharge amount of the two pumps. Note that the pulling side and the returning side may be reversed depending on the type of work, and may be set freely according to the operator's preference. Further, at the time of the combined operation of the first actuator 3 and the second actuator 19, since there is no imbalance in the speed of the first actuator 3 and the second actuator 19, the operation becomes easy, and the work operability and work efficiency are improved.
When the operation of the second pilot valve 17 is stopped, the operation automatically returns to a state where the speed can be increased when the first actuator 3 is operated alone in one direction.

The pressure change rate per unit time in the pilot pressure receiving portion 5a of the junction switching valve 5 is determined by the electromagnetic switching valve 7
The pressure is reduced by a throttle 23 (an example of a buffering means) provided in a pilot pipe connecting the air pressure and the pilot pressure receiving portion 5a. For this reason, as shown in FIG. 2, the flow rate of the pressure oil supplied to the first actuator 3 depends on the normal speed of the first actuator only for the first pump (during combined operation), and the flow rate of the first pump It changes smoothly at the time of switching from the speed increase due to the merge (independent operation). Therefore, the impact of not only the hydraulic device of the hydraulic excavator but also the entire hydraulic excavator is reduced, and the durability is improved. Also, the throttle 23 as a buffer means for reducing the rate of pressure change only reduces the switching speed of the junction switching valve 5, but does not reduce the switching speed of the first directional switching valve 2, so that the work machine operation speed decreases. Therefore, the working efficiency is not reduced.

In this embodiment, the electromagnetic switching valve 7 and the pilot pressure receiving section 5 serve as buffer means for reducing the rate of pressure change.
The throttle 23 is interposed in the pilot line connecting to the controller a, but the present invention is not limited to this.
The signal output from the solenoid valve 5 to the electromagnetic switching valve 7 may be smoothly changed at the time of switching.

Next, a second embodiment will be described with reference to FIG. The same components as those in the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. In the first embodiment shown in FIG. 1, when the second pilot valve 17 is neutral, the electromagnetic switching valve 7 is demagnetized regardless of the operation of the first pilot valve 9, and when the second pilot valve 17 is operated, the electromagnetic switching valve 7 is demagnetized. The switching valve 7 was excited to drain the pilot pressure receiving portion 5a of the junction switching valve 5. On the other hand, in the second embodiment, while operating the first pilot valve 9 to one side,
When the second pilot valve 17 is neutral, the electromagnetic switching valve 7 is excited, and when the second pilot valve 17 is operated, the electromagnetic switching valve 7 is demagnetized and the pilot pressure receiving portion 5a of the merge switching valve 5 is activated. It is the same as the first embodiment except that the configuration for draining is different.

Hereinafter, portions of the second embodiment that are different from the first embodiment will be described. A first pressure sensor 16 (an example of a specific operation detection sensor) that detects that the first pilot valve 9 has been operated on one side is connected to one pilot line 2a of the first direction switching valve 2. Controller 15
When the detection signal of the first pressure sensor 16 is input when the detection signal is not input from the second pressure sensors 21 and 22 when the speed increase function setting switch 26 is set to ON, the electromagnetic type The switching valve 7 is excited to switch to the position a. At the position a of the electromagnetic switching valve 7, the pilot pressure receiving portion 5a of the merge switching valve 5 is connected to one of the pilot lines 2a. Further, the controller 15 includes a first pressure sensor 16
When the detection signal is input, the second pressure sensor 2
When a detection signal is input from the terminals 1 and 22, the electromagnetic switching valve 7 is demagnetized and switched to the position b. At the position b of the electromagnetic switching valve 7, the pilot pressure receiving portion 5a of the merge switching valve 5 is drained.

When the speed-up function setting switch 26 is set to OFF, the controller 15 always demagnetizes the electromagnetic switching valve 7 and switches both the electromagnetic switching valve 7 and the merge switching valve 5 to the position b. To disable the speed increase function.

The operation of this embodiment will be described. First, after setting the speed-up function setting switch 26 to ON, if the second actuator 19 is not operated while the first actuator 3 is operated, the electromagnetic switching valve 7 is excited to activate the merging switching valve 5. The pilot pressure receiving portion 5a is connected to one pilot line 2a of the first directional control valve 2. For this reason, the discharge oil of the first pump 1 and the second pump 4 is supplied to the first actuator 3 to increase the speed. At this time,
When the second actuator 19 is operated, the controller 1
5 receives detection signals from the second pressure sensors 21 and 22 and demagnetizes the electromagnetic switching valve 7 while the second actuator 19 is being operated to drain the pilot pressure receiving portion 5a of the merging switching valve 5. Therefore, the first actuator 3
, Only the discharge oil of the first pump 1 is supplied to reach the normal speed. As described above, the electromagnetic switching valve 7 is demagnetized during the combined operation of the first actuator 3 and the second actuator 19 so that the first actuator 3 is set to a normal speed. Therefore, when the electromagnetic switching valve 7 is not excited due to a failure, Since the first actuator 3 always has a normal speed and is not increased in speed, work operability is improved, and a combined operation of the first actuator 3 and the second actuator 19 is possible.

The speed-up function setting switch 26 is turned off.
By disabling the speed increasing function by the controller 15, the discharge oil of the first pump 1 is supplied to the first actuator 3, and the discharge oil of the second pump 4 is supplied to the second actuator 19. A normal hydraulic circuit operating at normal speed can also be used.

The operation and effect of the present invention will be described above. (1) When the specific work machine is operated in one direction alone, the speed is increased by driving with a plurality of pumps.
In the case of a combined operation with another working machine, each of them is driven by one pump to maintain a normal speed. Therefore, the speed-up function of a specific work machine suitable for a specific work purpose can be selected, so that work efficiency can be improved. At this time, since the speed increasing function is automatically switched, the operator does not need to perform the switch switching operation, and can concentrate on the operation of the work machine, so that the operability is improved. (2) First actuator 3 and second actuator 19
In the combined operation with the above, there is no speed imbalance between the first actuator 3 and the second actuator 19, so that the operation becomes easy, and the work operability and work efficiency are improved. Further, when the operation of the second pilot valve 17 is stopped, the operation automatically returns to a state where the speed can be increased when the first actuator 3 is operated alone in one direction, so that the manual operation of the speed increase switching becomes unnecessary and the operability is reduced. Can be improved. (3) The flow rate of the pressure oil supplied to the first actuator 3 changes smoothly when only the first pump is switched and when the first and second pumps are merged. In addition, the impact of the entire hydraulic excavator is reduced, and the durability is improved. In addition, the throttle 23 as a buffer means for reducing the rate of pressure change only reduces the switching speed of the merging switching valve 5 and does not reduce the switching speed of the first directional switching valve 2, so that the work efficiency can be maintained.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for operating a working machine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in flow rate of a first actuator when one pump and two pumps are switched.

FIG. 3 is a hydraulic circuit diagram for working machine operation according to a second embodiment of the present invention.

FIG. 4 is a conventional hydraulic circuit diagram for working machine operation.

[Explanation of symbols]

1; first pump; 2; first directional control valve; 2a; one pilot line; 3; first actuator; 3a;
One port, 4; second pump, 5;
5a: pilot pressure receiving section, 7: solenoid switching valve,
9; first pilot valve, 15; controller, 1
6; first pressure sensor, 17; second pilot valve, 1
8; second directional control valve; 19; second actuator
21, 22; second pressure sensor, 23; throttle, 26;
Speed-up function setting switch.

Claims (3)

[Claims] The first pump is connected to a first actuator via a pilot-operated first directional control valve controlled by a first pilot valve, and a pilot-operated merger controlled by the first pilot valve is provided. The second pump is connected to one port of the first actuator via a switching valve, and one pilot line of the first directional switching valve and a pilot pressure receiving portion of the merge switching valve are connected via an electromagnetic switching valve. When the pilot pressure receiving portion of the merge switching valve is connected to the pilot line on one side of the first directional switching valve by an electromagnetic switching valve, the second pump communicates with the port on one side of the first actuator. When the pilot pressure receiving portion of the merge switching valve is drained by the electromagnetic switching valve, the hydraulic excavator is configured to cut off the second pump and the port on one side of the first actuator. In the hydraulic circuit for industrial machine operation, a second directional control valve (18) connected to the second pump (4) via a merge switch valve (5) and a second directional control valve (18) controlled by the second directional control valve (18). Two actuators (19) and a second actuator (1
9) Other operation detection sensor (21, 2
2) and when the detection signals of the other operation detection sensors (21, 22) are not input, the pilot pressure receiving portion (5a) of the merge switching valve (5) is connected to one of the pilot lines of the first directional switching valve (2). If the command to connect to (2a) is output to the electromagnetic switching valve (7) and a detection signal from any of the other operation detection sensors (21, 22) is input, only while this detection signal is being input And a controller (15) for outputting a command for switching the pilot pressure receiving portion (5a) of the merge switching valve (5) to the tank (25) for connection to the electromagnetic switching valve (7). Hydraulic circuit for operating excavator work equipment. 2. The hydraulic circuit for operating a working machine of a hydraulic excavator according to claim 1, further comprising a specific operation detecting sensor for detecting that the first directional control valve is operated to one side. At the same time, the controller inputs the detection signal from the specific operation detection sensor (16) and, when the detection signal of the other operation detection sensor (21, 22) is not input, excites the electromagnetic switching valve (7) and joins. Switching valve (5)
A hydraulic circuit for operating a working machine of a hydraulic excavator, wherein the pilot pressure receiving portion (5a) is connected to one of the pilot lines (2a) of the first directional control valve (2). 3. The hydraulic pressure circuit for operating a working machine of a hydraulic excavator according to claim 1, wherein the pilot pressure receiving portion (5a) at the time of switching of the merge switching valve (5).
Buffer means to reduce the pressure change rate per unit time
3) A hydraulic circuit for operating a working machine of a hydraulic excavator, comprising: