JP3531904B2 - Hydraulic control circuit of work machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of hydraulic control circuits for working machines such as hydraulic excavators.

[0002]

2. Description of the Related Art Generally, some working machines such as hydraulic excavators are provided with an offset type working unit which swings to the left and right. In such a working machine, the working unit is moved when the working unit is moved. There is a risk of contact (interference) with the driver's seat, and in such a case, consideration must be taken to avoid contact between the working part and the driver's part. Therefore, conventionally, an attitude detection unit that detects the attitude of the working unit, and a control unit that determines whether the working unit is approaching within a predetermined range of the driver's seat unit based on a detection signal from the attitude detecting unit. If it is determined that the working unit is approaching within a predetermined range of the driver's seat, the control unit outputs a control command to the hydraulic circuit of the working unit hydraulic actuator to turn the working unit on. There are some that were stopped. As such a thing, for example, a thing as shown in FIG. 6 is known, but this thing has a pilot type control valve 46 for controlling pressure oil supply to a hydraulic actuator 45 such as a boom cylinder. , A pilot valve 4 that outputs pilot pressure oil based on the operation of the operation tool 47
Between 8A and 48B, electromagnetic proportional pressure reducing valves 49A and 49B that operate based on a command from the control unit are provided. When the working unit is separated from the driver's seat, the electromagnetic proportional pressure reducing valves 49A and 49B are opened to allow the pilot pressure oil to be supplied to the control valve 46, while the working unit approaches the driver's seat. If so, the electromagnetic proportional pressure reducing valves 49A and 49B are closed and the control valve 46 is closed.
The operation of the working unit is stopped by cutting off the supply of pilot pressure oil to the unit.

[0003]

By the way, the above-mentioned prior art, as described above, closes the electromagnetic proportional pressure reducing valve and stops the working part when the working part approaches the driver's seat. There is a problem that the working unit is stopped during the work and the work efficiency is reduced, and there is a problem to be solved by the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in order to solve these problems, and a hydraulic actuator that operates to move a working unit, Supply of pilot pressure oil to the control valve to a hydraulic control circuit of a working machine comprising a pilot type control valve for controlling pressure oil supply to the hydraulic actuator based on a command from a control unit. A control valve for controlling, a pilot valve for outputting pilot pressure oil to the control valve based on operation of an operating tool, and a pilot pump capable of supplying pilot pressure oil from a pilot hydraulic pressure source to the control valve without passing through the pilot valve Oil passage and the pilot valve
Is installed in the pilot oil passage from the
Pilot pump when the operation tool is not operated
First position to supply pilot pressure oil from oil passage to control valve
Pyro based on the operation of the controls
Pressure output from the control valve corresponding to the operation amount
Switch to the second position to supply pilot pressure oil to the control valve.
And a control valve for determining whether or not the working unit has entered a preset interference prevention area based on an input signal from a posture detecting unit that detects the posture of the working unit. When the determination unit determines that the working unit has entered the interference prevention area by the determination unit, the control valve supplies pilot pressure oil to the control valve in a direction in which the working unit moves away from the interference prevention region. A hydraulic control circuit for a working machine provided with an interference prevention control means for outputting a control command. By doing this, if the working part enters the interference prevention area during work,
Since the pilot pressure oil is automatically supplied in the direction in which the working unit moves away from the interference prevention area, the work can be continued while avoiding the interference prevention area. In this one, as a hydraulic actuator for moving the working part, a boom up / down cylinder for vertically swinging an offset type boom that can swing vertically and horizontally, a boom left / right cylinder for horizontally swinging, and a boom A stick cylinder for swinging the stick, which is swingably supported back and forth, at the tip of the stick, and supplies pilot pressure oil to the control valve of the stick cylinder in a direction to move the stick away from the interference prevention area. The control valve, pilot valve, pilot pump oil passage, and switching valve are provided in the oil passage to be installed, and the boom or stick is in the interference prevention area on the control valves for the boom up / down cylinder, boom left / right cylinder, and stick cylinder. Supply pilot pressure oil in the approaching direction In the case where the control valve and pilot valve are provided in each oil passage, the pilot pump oil passage is used to supply the pilot pressure oil in the direction to move the stick away from the interference prevention area in the circuit where the conventional working unit stops. And by only providing the switching valve, the work can be continued while avoiding the interference prevention area, and the circuit can be simplified.
It can contribute to the suppression of cost increase.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1 and FIG. 2, reference numeral 1 denotes an offset type hydraulic excavator, and the hydraulic excavator 1 is composed of a lower traveling body 2, an upper revolving superstructure 3, a cab 4, a working portion 5, and the like. The working unit 5 includes a rear boom 6 whose base end is swingably supported by the upper swing body 3, a front boom 7 which is swingably supported by the tip of the rear boom 6, and a front boom 7. A stick 8 supported on the tip end portion so as to be swingable left and right and forward and backward, a bucket 9 supported at the tip end portion of the stick 8 so as to be swingable forward and backward, and a boom cylinder for swinging these (the boom of the present invention. It is composed of an up / down cylinder) 10, an offset cylinder (corresponding to the boom left / right cylinder of the present invention) 11, a stick cylinder 12, a bucket cylinder 13 and the like. The basic structure of such that there is conventional, in the present embodiment, the cab 4 is provided on the left side of the upper revolving structure 3. Further, the rear boom 6 descends as the boom cylinder 10 contracts, and the boom cylinder 1
It is configured to rise as 0 expands. Further, the front boom 7 is configured to move to the left when the offset cylinder 11 is contracted, that is, in the direction toward the cab 4, and to the right when the offset cylinder 11 is extended. Furthermore, the stick 8 is configured to swing (stick in) toward the rear side of the machine body when the stick cylinder 12 extends, and swings toward the front side of the machine body (stick out) when the stick cylinder 12 contracts. ing.

The pressure oil supply control to each of the cylinders 10 to 13 will be described based on the hydraulic control circuit diagram shown in FIG. 3. In FIG. 3, 14 is a main pump, 15 is a pilot pump, 16 is an oil tank, Further, 17 to 20 are control valves for boom, offset, stick, and bucket, and these control valves 17 to 20 are reduction-side pilot ports 17a to 20a.
And a pilot-operated three-position switching valve having extension side pilot ports 17b to 20b.
The control valves 17 to 20 are in the neutral position where the pressure oil supply to the corresponding cylinders 10 to 13 is stopped in a state where the pilot pressure oil is not supplied to the pilot ports 17a to 20b and 17b to 20b. Although located at N, the reduction side pilot ports 17a to 20
By supplying the pilot pressure oil to a, the cylinder 10
By switching to the reduction side position X where the pressure oil from the main pump 14 is supplied to the reduction side oil chambers of # 13 to # 13, and the pilot pressure oil is supplied to the extension side pilot ports 17b to 20b, Main pump 1 in extension side oil chamber
It is configured to switch to the extension side position Y for supplying pressure oil from 4.

Reference numerals 21 to 24 are for booms for supplying pilot pressure oil to the pilot ports 17a to 20a and 17b to 20b of the control valves 17 to 20 based on the operation of an operating tool (not shown). These are pilot valves for offset, stick, and bucket, and these pilot valves 21 to 24 are composed of reduction side pilot valves 21A to 24A and extension side pilot valves 21B to 24B, respectively. And, these pilot valves 21-24, when the corresponding operation tool is in the neutral state (when not operated),
Pump port 21a connected to pilot pump 15
~ 24a is closed and the tank ports 21b to 24b connected to the oil tank 16 and the output ports 21c to 24c are in communication with each other, but they are operated by operating the operation tool toward the contraction side or the extension side. Side pilot valve 21
A to 24A or 21B to 24B output ports 21c to
24c communicates with the pump ports 21a to 24a, whereby the pilot pressure oil having a pressure corresponding to the operation amount of the operation tool is output from the output ports 21c to 24c. In FIG. 3, reference numerals 25, 26, and 27 denote a turning motor, a turning control valve, and a turning pilot valve for turning the upper turning body 3, respectively.

[0008] Further, the boom reduction pilot oil passage connecting the boom reduction pilot valve 21A and the boom control valve reduction pilot port 17a, the boom extension pilot valve 21B and the boom control valve extension pilot. Port 17b
Boom extension side pilot oil passage, which is connected to the boom, Offset reduction side pilot valve 22A and offset control valve Reduction side pilot oil passage that connects the reduction side pilot port 18a, Stick extension side pilot valve 23B and stick Control valve expansion side pilot port 19b is connected to each of the stick extension side pilot oil passages in the respective pilot oil passages. The boom reduction side, the boom extension side, the offset reduction side, and the stick extension side Proportional pressure reducing valves 28, 29, 30, 31 are provided, but since these electromagnetic proportional pressure reducing valves 28, 29, 30, 31 are similar, taking the boom reducing side electromagnetic proportional pressure reducing valve 28 as an example. Explaining the electromagnetic proportional pressure reducing valve 28, the first to third ports 28a, 8b, 28c, and the solenoid 2
8d, but the first port 28a is the oil tank 16
The second port 28b is connected to the output port 21c of the boom reduction side pilot valve 21A, and the third port 28c is connected to the reduction side pilot port 17a of the boom control valve 17. The electromagnetic proportional pressure reducing valve 28 opens the valve passage that connects the first port 28a and the third port 28c and closes the second port 28b when the solenoid 28d is not excited.
Oil from the reduction side pilot port 17a is stored in the oil tank 16
The solenoid 28d is excited based on an operation command from the control unit 32, which will be described later, to open the output valve path that connects the second port 28b and the third port 28c. Is configured. When the output valve path is opened, pilot pressure oil from the pilot valve output port 21c is output to the control valve reduction side pilot port 17a. It is adapted to increase / decrease according to the control command output to the excitation circuit of 28d.

On the other hand, in the reduction side pilot oil passage for the stick connecting the reduction side pilot valve for stick 23A and the control valve reduction side pilot port for stick 19a, a switching valve 33 and an electromagnetic proportional pressure reducing valve for the reduction side for stick are provided. 34 are provided. The switching valve 33 is a five-port two-position switching valve. The first port 33a is the oil tank 16 and the second port 33b is the output port 23 of the stick reduction pilot valve 23A.
c, the third port 33c is in the pilot pump oil passage P,
The fourth port 33d is connected to the first port 34a of the stick-side reduction side electromagnetic proportional pressure reducing valve 34, and the fifth port 33e is connected to the second port 34b of the stick-side reduction side electromagnetic proportional pressure reducing valve 34. Here, the pilot pump oil passage P is an oil passage extending from the upstream side of the stick pilot valve 23 to the switching valve 33, and the pressure oil from the pilot pump 15 is transferred by the pilot pump oil passage P to the stick pilot valve. It is supplied to the switching valve 33 without passing through 23. Further, the switching valve 33 is provided with a pilot port 33f, and the pilot port 33f is connected to a pilot oil passage connecting the reduction side pilot valve output port 23c for stick and the switching valve second port 33b. hand,
As pilot pressure oil is output from the reduction side pilot valve 23A for sticks, the pilot port 33
Pilot pressure oil is also supplied to f.
Further, this switching valve 33 is provided with an ammunition 33g when the pilot pressure oil is not supplied to the pilot port 33f.
The first position 33a is closed by the urging force of the first port 33a, the valve passage from the third port 33c to the fifth port 33e is opened, and the valve passage from the fourth port 33d to the second port 33b is opened. The pilot pressure oil from the pilot pump oil passage P is supplied to the electromagnetic proportional pressure reducing valve second port 34b.
Can be supplied to the electromagnetic proportional pressure reducing valve first port 34a
Oil from the oil tank 1 via the pilot valve 23A
It can be discharged to 6. On the other hand, when pilot pressure oil is supplied to the pilot port 33f, the third port 33c is closed, the valve passage from the second port 33b to the fifth port 33e is opened, and the fourth port 33d to the first port 33a. To the second position Y for opening the valve passage leading to the valve, the pilot pressure oil from the pilot valve output port 23c can be supplied to the electromagnetic proportional pressure reducing valve second port 34b, and the oil from the electromagnetic proportional pressure reducing valve first port 34a can be supplied. Can be discharged to the oil tank 16.

The electromagnetic proportional pressure reducing valve 34 on the reduction side for sticks is the electromagnetic proportional pressure reducing valves 28, 29, 3 described above.
The output pressure is increased or decreased in response to a control command from the control unit 32, which has the same structure as 0 and 31, but the first port 34a of this output port has a fourth port 33d of the switching valve 33. The second port 34b is connected to the switching valve fifth port 33e, and the third port 34c is connected to the reduction side pilot port 19a of the stick control valve 19. The electromagnetic proportional pressure reducing valve 34 on the reducing side for sticks opens the valve path that connects the first port 34a and the third port 34c and closes the second port 34b when the solenoid 34d is not excited. The oil from the reduction side pilot port 19ab is made to flow to the oil tank 16, but the solenoid 34d is excited based on the operation command from the control unit 32, so that the second port 34b and the third port 34c are excited. Is configured to open an output valve passage that communicates with. Then, the switching valve 3 at the first position X is opened by opening the output valve path.
The pilot pressure oil from the pilot pump oil passage P passing through No. 3 or the pilot pressure oil from the pilot valve 23A passing through the switching valve 33 at the second position Y is output to the control valve reduction side pilot port 19a. ing.

Further, 35 is a solenoid valve for locking,
This is the same as the pump ports 21a to 24a of the pilot valves 21 to 24 and the third port 3 of the switching valve 33.
3c is arranged on the primary side (upstream side). The locking solenoid valve 35 operates the locking operation tool (not shown) by an operator to supply pilot pressure oil from the pilot pump 15 to the pilot valve 21.
~ 24 and the unlocked position X output to the switching valve 33,
It is configured to switch to a lock position Y where pilot pressure oil is not output.

On the other hand, the control unit 32 is constructed by using a microcomputer or the like. In this control unit, a boom angle sensor 36 for detecting the relative angle of the rear boom 6 with respect to the upper swing body 3 and a front boom are included. An offset angle sensor 37 for detecting a relative angle of the rear boom 6 to the stick 7, a stick angle sensor 38 for detecting a relative angle of the stick 8 to the front boom 7, and detection of output of pilot pressure oil from the boom reduction side pilot valve 21A. Boom reduction side pressure sensor 39
A, similarly, for booms that detect the output of pilot pressure oil from each of the pilot valves 21B, 22A, 23A, and 23B on the extension side for booms, the reduction side for offsets, the reduction side for sticks, and the extension side for sticks. Pressure sensors 39B and 40 on the extension side, the offset reduction side, the stick reduction side, and the stick extension side, respectively.
Signals from A, 41A, 41B, etc. are input, and based on these input signals, the boom reduction side, the boom extension side, the offset reduction side, the stick reduction side, and the stick extension side. Each electromagnetic proportional pressure reducing valve 2
It is configured to output a control command to 8, 29, 30, 34, 31 and the like.

Incidentally, the extension side pilot oil passage for offset connecting the extension side pilot valve 22B for offset and the control valve extension side pilot port 18b for offset, and the reduction side pilot valve 24A for bucket.
Contraction side pilot oil passage for connecting the control valve for contraction side and the control valve for expansion side for bucket 20a, and the expansion side pilot oil for bucket connecting the expansion side pilot valve 24B for bucket and the control valve expansion side pilot port 20b for bucket An electromagnetic proportional pressure reducing valve that operates according to a command from the control unit 32 is not provided in each pilot oil passage of the passage, and each of the pilot valves 22B, 24A, 24 described above is operated based on the operation of the operation tool.
The pilot pressure oil output from B is directly supplied to the pilot ports 18b, 20a, 20b. That is, the right offset and the operation of the bucket 9 are configured to be always performed in response to the operation of the operation tool, without being involved in the interference prevention control of the control unit 32 described later.

Next, the interference prevention control in the control unit 32 will be described with reference to the block diagram shown in FIG. 4. First, the control unit 32 outputs the boom angle sensor 36, the offset angle sensor 37, and the stick angle sensor 38. The attitude calculator 42 calculates the attitude (position) of the working unit 5 based on the detection signal. On the other hand, the memory 3 of the control unit 32
2a includes an interference prevention region (for example, cab 4) which is set so that working unit 5 should not approach cab 4 any more.
(Within a range of 300 mm from) H is stored. Then, the control unit 32 performs a comparison calculation of the posture of the working unit 5 calculated by the posture calculation unit 42 and the interference prevention area H stored in the memory 32a by the comparison calculation unit 43, and outputs the calculation result as an output signal. Output to the container 44. Further, the output signal calculator 44 includes pressure sensors 39A, 39B, 4 for the boom reduction side, the boom extension side, the offset reduction side, the stick reduction side, and the stick extension side.
The signals from 0A, 41A and 41B are input.

The output signal calculator 44 includes a comparison calculator 43 and pressure sensors 39A, 39B, 40A and 4A.
Electromagnetic proportional pressure reducing valves 2 for boom reduction side, boom extension side, offset reduction side, stick reduction side, and stick extension side 2 based on input signals from 1A and 41B.
The control command is output to the solenoid exciting circuits of 8, 29, 30, 34, 31. That is, the output signal calculator 44
When it is calculated by the comparison calculator 43 that the working unit 5 is separated from the interference prevention area H by a predetermined range or more, the pressure sensors 39A, 39B, 40 are
Electromagnetic proportional pressure reducing valves 28, 29, 3 in the pilot oil passage in which the output of pilot pressure oil is detected by A, 41A, 41B
A solenoid excitation command is output to 0, 34, 31 so as to fully open the output valve path. Accordingly, when pilot pressure oil is output from each of the pilot valves 21A, 21B, 22A, and 23B on the boom reduction side, the boom extension side, the offset reduction side, and the stick extension side based on the operation of the operation tool, The pilot pressure oil passes through the fully-opened electromagnetic proportional pressure reducing valves 28, 29, 30, 31 and the control valve pilot ports 17a, 17b, 18 as they are.
a, 19b. Further, the switching valve 33 is provided in the reduction side pilot oil passage for the stick, but the switching valve 33 is, as described above,
When pilot pressure oil is being output from the reduction side pilot valve 23A for sticks based on the operation of the operation tool, the pilot valve 23A is switched to the second position Y.
Is supplied to the electromagnetic proportional pressure reducing valve 34. Therefore, when the pilot pressure oil is output from the stick reduction side pilot valve 23A based on the operation of the operation tool, the pilot pressure oil is output. The oil is supplied to the control valve pilot port 19a via the switching valve 33 at the second position Y and the electromagnetic proportional pressure reducing valve 34 which is fully opened. That is, when the working unit 5 is separated from the interference prevention area H by a predetermined distance or more, the working unit 5
It operates according to the operation of the operation tool.

On the other hand, when the comparison calculator 43 calculates that the working unit 5 is approaching the interference prevention area H within a preset range, the output signal calculator 4
4 is the pressure sensor 39A, 39B, 40A, 41
Electromagnetic proportional pressure reducing valves 28, 29, 30, 3 in the pilot oil passage in which the output of pilot pressure oil is detected by A and 41B
A solenoid excitation command is output to 4 and 31 to open the output valve path. In this case, the electromagnetic proportional pressure reducing valves 28, 2
The opening amounts of the output valve passages of 9, 30, 34, and 31 are such that the closer the working unit 5 is to the interference prevention region H, the electromagnetic proportional pressure reducing valve 28,
The output pressure from 29, 30, 34, 31 is adjusted to be small. As a result, each of the pilot valves 21A, 21B, 22A, 23A, and 23B on the boom reduction side, the boom extension side, the offset reduction side, the stick reduction side, and the stick extension side is operated based on the operation of the operation tool.
When the pilot pressure oil is output from the control valve pilot pressure oil, the pilot pressure oil is supplied to the control valve pilot ports 17a, 17b, 18a, 19a, 19b while being reduced in pressure by the electromagnetic proportional pressure reducing valves 28, 29, 30, 34, 31. To be done. That is, when the working unit 5 approaches within the predetermined interval of the interference prevention area H, the boom descending and ascending, left offset, stick-in and stick-out operations are performed in a decelerated state.

On the other hand, the working unit 5 is operated by the comparison calculator 43.
Is calculated to have reached the outer boundary of the interference prevention region H, the output signal calculator 44 determines the electromagnetic proportional pressure reducing valves 28, 29, 30, 31, 3 based on the control command table shown in FIG.
4 outputs a control command to the No. 4 in the present embodiment. As the interference prevention region H, two regions, that is, the front and side (front and right side) interference prevention regions of the cab and the roof roof interference prevention region of the cab are provided. It is set and each area is controlled separately. FIG. 5 shows the relationship between the operating state of the operating tool and the operation command to the working unit 5.
In this model, the boom down, boom up, stick out, stick in, and left offset operation states are the pressure sensors on the boom reduction side, boom extension side, stick reduction side, stick extension side, and offset reduction side, respectively. 39A, 39B, 41A, 41B, 40A
Judgment is based on the detection signal input from. Further, regarding the boom descending, boom ascending, stick out, and left offset operation commands, the electromagnetic proportional pressure reducing valves 28, 29, 34 for the boom reducing side, the boom extending side, the stick reducing side, and the offset reducing side, respectively. A solenoid excitation command is output to 30 to open the output valve path. In addition, the boom down stop, boom up stop, stick-in stop, stick-out stop, and left offset stop operation commands are the boom reduction side, boom extension side, stick extension side, stick reduction side, and offset side, respectively. Electromagnetic proportional pressure reducing valves 28, 29, 31, 3 on the reduction side
A solenoid non-excitation command is output to 4 and 30 to close the output valve path. Since the boom down, boom up, and left offset operation commands are output while the boom down, boom up, and left offset operations are performed, the electromagnetic proportional pressure reducing valves 28, 29, 30 output. When the valve passage opens, the pilot valves 21A, 21
The pilot pressure oil output from B and 22A is supplied to the control valve pilot ports 17a, 17b and 18a. On the other hand, since the stick-out operation command is output in the state where the stick-out operation is not performed, the pilot pressure oil is not output from the pilot valve 23A, but the pilot pressure oil is output from the pilot valve 23A. In the absence state, as described above, the switching valve 3 provided in the reduction side pilot oil passage for the stick
Since 3 is located at the first position X, pilot pressure oil from the pilot pump oil passage P passes through the switching valve 33 and the electromagnetic proportional pressure reducing valve 34 at the first position X to the control valve pilot port 19a. Supplied.

First, the control when the working unit 5 reaches the outer boundary of the interference prevention area H in the front / side interference prevention area will be described with reference to FIG. If done,
Boom down and stick out operation commands are output. This prevents the working unit 5 from entering the interference prevention area H by pulling out the stick 8,
The boom lowering operation can be continued. in this case,
The working unit 5 descends substantially along the outer boundary of the interference prevention region H. When the stick-in operation is performed independently, the stick-in stop operation command is output, and when the left offset operation is performed independently, the left offset stop operation command is output. . When the boom lowering and stick-in operations are combined, the boom lowering and stick-out operation commands are output, and when the boom lowering and left offset operations are combined, the boom lowering is performed. , Stick-out and left-offset operation commands are output, and when stick-in and left-offset operations are combined, stick-out and left-offset operation commands are output.
When the boom lowering, stick-in and left offset operations are combined, a boom lowering, stick-out and left offset operation command is output.
As a result, the boom descending operation and the left offset operation can be continued while preventing the working unit 5 from entering the interference prevention area H by pulling out the stick 8. In this case, the working unit 5 moves substantially along the outer boundary line portion of the interference prevention region H. When the boom raising operation is independently performed, the boom raising and stickout operation commands are output. As a result, it is possible to continue the boom raising operation while preventing the working unit 5 from entering the interference prevention area H by pulling out the stick 8. In this case, the working unit 5 moves substantially along the outer boundary line portion of the interference prevention region H. When the boom up and stick-in operations are combined, the boom up and stick-out operation commands are output, and when the boom up and left offset operations are combined, the boom up operation is performed. , Stick-out and left-offset operation commands are output, and when boom-up, stick-in and left-offset operations are combined, boom-up, stick-out and left-offset operation commands are output. . This prevents the working unit 5 from entering the interference prevention area H by pulling out the stick 8,
Boom up and left offset operation can be continued. In this case, the working unit 5 moves along the outer boundary line portion of the interference prevention area H. Also, this front
In the control of the side interference prevention area, if the stick-out operation is performed alone or in combination with the above-mentioned operations (the stick-out operation and the stick-in operation are not performed at the same time, of course), The stick-out operation command is output alone or in combination with each operation command.

Next, in the roof interference prevention area, the control when the working portion 5 reaches the outer boundary line portion of the interference prevention area H will be described. When the boom lowering operation is performed independently, When the boom down stop operation command is output and the stick-in operation is performed independently, the stick-in stop operation command is output, and when the stick-out operation is performed independently, the stick-out operation is performed. A stop operation command is output. Regarding the operation command when the boom lowering operation is independently performed, the angle of the stick 8 is an elevation angle as in the case where the boom lowering and stick-in operations described below are combined. It can sometimes be set to output boom down and stick out operation commands. In this case, the boom lowering operation can be continued while the stick 8 is pulled out and the working unit 5 is prevented from entering the interference prevention area H. When the boom lowering and stick-in operations are combined, a boom lowering and stick-out operation command or a boom lowering stop and stick-in stop operation command is output depending on the attitude of the stick 8. That is, as shown in FIG. 6 (A), when the angle of the stick 8 with respect to the vertical line L passing through the swing fulcrum of the stick 8 is an elevation angle, a boom descending and sticking out operation command is output. , Stick 8
The boom lowering operation can be continued while the work portion 5 is prevented from entering into the interference prevention area H by turning off. In this case, the working unit 5 moves along the outer boundary line portion of the interference prevention area H. In addition, FIG.
As shown in (B), when the angle of the stick 8 with respect to the vertical line L passing through the swinging fulcrum of the stick 8 is a depression angle,
Boom down stop and stick-in stop operation commands are output. When the boom lowering and stick out operations are combined, a boom lowering stop and stick out stop operation command is output. Also,
In this control of the roof interference prevention area, when a boom raising operation is performed, a boom raising operation command is output, and when a left offset operation is performed,
A left offset operation command is output, but the boom rises,
When the left offset operation is performed in combination with each of the above operations (the boom raising operation and the boom lowering operation are not performed at the same time, of course), the boom raising and left offset operations are performed together with the above operations. The operation command of is output. Incidentally, in any control of the front / side interference prevention region and the roof interference prevention region, the operation of the right offset and the bucket 9 does not participate in the interference prevention control as described above, and therefore corresponds to the operation of the operation tool. The operation is performed.

In the structure configured as described above, the working portion 5 operates in response to the operation of the operating tool when the working portion 5 is separated from the interference prevention area H by a predetermined distance or more as described above. When it approaches within the predetermined interval of the area H, it automatically decelerates, and when it reaches the interference prevention area H, it automatically stops according to the operation state of the operation tool and the posture of the working unit 5. Alternatively, it is possible to continue the lowering and raising of the boom 3 and the operation of the left offset while avoiding that the stick 8 automatically comes out and the working unit 5 enters the interference prevention area H.

As a result, for example, when the working unit 5 reaches the interference prevention area H during the boom lowering operation, the stick 8 automatically comes out to avoid the interference prevention area H and the boom 6 moves. Since the lowering operation is continued, the work does not stop as in the conventional case, and the work efficiency improves.

In addition, since this one is constructed such that the work can be continued while avoiding the interference prevention area H only by automatically turning off the stick 8, the hydraulic actuator for the stick out of the hydraulic actuators provided in the working section 5 can be used. It suffices to incorporate a circuit for automatically reducing the size of the cylinder only in the circuit of the cylinder 12, so that the circuit can be simplified and the cost increase can be suppressed.

Further, a circuit for automatically reducing the cylinder incorporated in the stick cylinder 12 circuit is incorporated in the stick reduction side pilot oil passage. In this case, the output from the pilot valve 23A is used. Pilot pressure oil and pilot pump oil passage P
One of the pilot pressure oils from the above is selected by the switching valve 33, and the selected pilot pressure oil is supplied to the electromagnetic proportional pressure reducing valve 34 which operates according to a command from the control unit 32. Since it is not necessary to add an expensive electromagnetic proportional pressure reducing valve to the conventional circuit for automatically stopping the cylinder, it is sufficient to provide the switching valve 33 and the pilot pump oil passage P. It can contribute to the suppression of cost increase.

It should be noted that the present invention is not limited to the above embodiment, and in the above embodiment, the switching valve 3 is used.
3 is configured to switch from the first position X to the second position Y by supplying pilot pressure oil to the pilot port 33f. This switching valve is based on a solenoid excitation command from the control unit. The solenoid valve is switched from the first position to the second position, and when the detection signal from the pressure reducing sensor for stick is input to the control unit, the control unit outputs a solenoid excitation command to switch the switching valve to the second position. You may make it the structure switched to a position.

[Brief description of drawings]

FIG. 1 is a side view of a hydraulic excavator.

FIG. 2 is a plan view of the hydraulic excavator showing a state where the front boom is swung left and right.

FIG. 3 is a hydraulic control circuit diagram of a hydraulic actuator.

FIG. 4 is a block diagram showing a control procedure of interference prevention control.

FIG. 5 is a table showing control commands for interference prevention control.

FIG. 6A shows a case where the stick angle is an elevation angle,
(B) is a diagram showing a case where the angle of the stick is a depression angle.

FIG. 7 is a hydraulic control circuit diagram of a hydraulic actuator showing a conventional example.

[Explanation of symbols]

4 cabs 5 Working department 10 Boom cylinder 11 Offset cylinder 12 Stick cylinder 17 Boom control valve 18 Offset control valve 19 Stick control valve 21A Boom reduction side pilot valve 21B Boom extension side pilot valve 22A Reduction side pilot valve for offset 23A Stick reduction side pilot valve 23B Stick extension side pilot valve 28 Reduced-side electromagnetic proportional pressure reducing valve for boom 29 Boom extension side electromagnetic proportional pressure reducing valve 30 Reduction-side solenoid proportional pressure reducing valve for offset 31 Extension side electromagnetic proportional pressure reducing valve for stick 32 control unit 33 Switching valve 34 Reduction side electromagnetic proportional pressure reducing valve for stick H interference prevention area P Pilot pump oil passage

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02F 3/43 E02F 9/24 F15B 11/16 F15B 20/00

Claims (2)

(57) [Claims] 1. A hydraulic control circuit for a working machine, comprising: a hydraulic actuator that operates to move a working unit; and a pilot-type control valve that controls pressure oil supply to the hydraulic actuator. Control valve that controls the supply of pilot pressure oil to the control valve based on a command from a control unit, a pilot valve that outputs pilot pressure oil to the control valve based on operation of an operating tool, and a pilot pressure source that supplies the pilot pressure oil to the control valve. Pilot pump oil passage that can supply pilot pressure oil to the control valve without going through the valve and control from the pilot valve
It is installed in the pilot oil passage between the valve and
From the pilot pump oil passage when no work is done
Located in the first position to supply pilot pressure oil to the control valve
The pilot bar based on the operation of the controls.
Of the pressure corresponding to the operation amount
A switching valve that switches to a second position for supplying lot pressure oil to the control valve is provided, and the control unit is preset by the working unit based on an input signal from a posture detecting unit that detects the posture of the working unit. Determination means for determining whether or not the working portion has entered the interference prevention area, and when the determination portion determines that the working portion has entered the interference prevention area, the working portion prevents the working portion from interfering with the control valve. A hydraulic control circuit for a working machine provided with interference prevention control means for outputting a control command to supply pilot pressure oil in a direction away from the area to a control valve. 2. A boom up / down cylinder for vertically swinging an up / down and left / right swingable offset boom and a boom for horizontally swinging as a hydraulic actuator for moving a working part. A direction for moving the stick away from the interference prevention area to the control valve of the stick cylinder, which is provided with a left and right cylinder and a stick cylinder for swinging the stick that is swingably supported back and forth at the tip of the boom. In the oil passage for supplying the pilot pressure oil of
Providing a pilot valve, pilot pump oil passage, and switching valve, and supplying pilot pressure oil in the direction in which the boom or stick approaches the interference prevention area to the control valves for the boom up / down cylinder, boom left / right cylinder, and stick cylinder. A hydraulic control circuit for work machines that has a control valve and a pilot valve in each oil passage.