JP2926035B1 - Hydraulic control circuit of work machine - Google Patents

Abstract

A hydraulic control circuit includes a control valve that operates in accordance with a command from a control unit in a pilot oil passage that connects a pilot valve and a control valve. The pilot pressure oil can be supplied to the control valve even if it does not operate due to a failure or the like. SOLUTION: In a pilot oil passage, a control valve 20A, which is operated with pressure oil from pilot valves 18A, 18B, is provided.
A first position X where a first valve path 19k for supplying to the control valve 17 via the control valve 20 is formed, and a second position for supplying pressure oil from the pilot valve to the control valve via the inactive control valve. Switching valves 19A and 19B capable of switching to the second position Y where the valve path 19i is formed are provided.

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 a hydraulic control circuit for a working machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art Generally, this kind of working machine includes:
When this is a hydraulic excavator, for example, an offset-type working unit may be attached. In such a case, when the working unit is moved, the working unit comes into contact with (interferes with) an evacuation interference site such as a driver's seat. In such a case, care must be taken to avoid contact between the working unit and the driver's seat. Therefore, a detection unit that detects the posture 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 portion based on a detection signal from the detection unit is provided, When 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 stop the working unit. ing.
As described above, as a hydraulic control circuit of a hydraulic actuator for a working unit in which the interference prevention control means for stopping the working unit when the working unit approaches the driver's seat is conventionally used, FIG.
The following are known. This includes a pilot-operated control valve 17 for controlling the supply of hydraulic oil to the hydraulic actuator S, and pilot valves 18A and 18B for supplying pilot hydraulic oil to the control valve 17 based on the operation of the operating tool 22. Between them, there are provided electromagnetic proportional pressure reducing valves 37A and 37B which operate based on a command from the control unit. When the working unit is not approaching the driver's seat, the electromagnetic proportional pressure reducing valves 37A and 37B are opened to allow the supply of pilot pressure oil to the control valve 17, while the working unit is in the driver's seat. When approaching, the electromagnetic proportional pressure reducing valves 37A, 37B
To shut off the supply of the pilot pressure oil to the control valve 17, thereby stopping the working unit.

[0003]

However, in the conventional hydraulic control circuit, when the drive circuit of the electromagnetic proportional control valve fails or breaks, the electromagnetic proportional pressure reducing valve does not operate, or the control unit fails. When the output of the control command to the electromagnetic proportional pressure reducing valve is stopped, the electromagnetic proportional valve remains closed and the supply of pilot pressure oil to the control valve is cut off. However, there is also a problem that the working unit does not move, and there is a problem to be solved by the present invention. Further, in recent years, automatic control for automatically moving the work unit based on a command from the control unit has been attempted in order to improve the work efficiency and the operability. When an attempt is made in the control circuit, despite the provision of an electromagnetic proportional control valve that operates based on a command from the control unit, the electromagnetic proportional pressure reducing valve functions to control pilot pressure oil supplied from the pilot valve. Therefore, there is also a problem to be solved that automatic control using the electromagnetic proportional pressure reducing valve cannot be performed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made for the purpose of solving these problems, and is provided for controlling supply of pressurized oil to a hydraulic actuator. a control valve of a pilot-operated, a pilot valve for supplying pilot pressure oil to the control valve based on the operation of the operating member, disposed in the pilot oil path connecting the these pilot valve and the control valve, operated instrument operation Pyro accompanying
Pi from the control valve to the control valve
Control of lot pressure oil output pressure control command from control unit
A hydraulic control circuit for a working machine comprising a control valve based on the control valve, wherein the hydraulic oil from the pilot valve is supplied to the control valve via the control valve in an operating state in the pilot oil passage. It is possible to switch between a first position where one valve path is formed and a second position where a second valve path for supplying pressure oil from the pilot valve to the control valve via a non-operating control valve is formed. Switching valve provided
At the same time, the switching valve is inactive.
Piping to the control valve by operating the operating tool in an emergency
Switch to the second position to supply lot pressure oil
It is characterized in that it is configured to
You. In this way, even when the control valve does not operate due to a failure in the drive circuit, the control valve is switched to the second position, thereby allowing the control valve in the non-operating state to release the pressure oil from the pilot valve. Thus, the workability can be improved. In this case, the switching valve is switched to the second position in an emergency
As a means for interlocking with the ON operation of the emergency switch
Supply pilot pressure oil to switch the switching valve to the second position
An emergency switching valve for
The connection with the control unit is established based on the ON operation of the emergency switch.
Equipped with a solenoid that disconnects and holds the switching valve in the second position
Can be configured with an electromagnetic switching valve
You. In this way, emergency operation is ensured.
Wear. Further, in the switching valve in which a third valve path for supplying the hydraulic oil from the pilot hydraulic pressure source to the control valve via the control valve in an operating state in a state where the switching valve is switched to the second position is provided, Automatic control for controlling the supply of pilot pressure oil to the control valve using a control valve that operates based on a command from the unit can be performed, which is convenient. In this device, the return oil from the control valve is formed in the first position by forming a fourth valve path for discharging the return oil from the control valve to the oil tank in a state where the return oil is switched to the first position in the switching valve. It can be discharged via a switching valve. Further, by configuring the switching valve to return the return oil from the control valve to the pilot valve via the second valve path in a state where the return oil is switched to the second position, the return oil from the control valve is discharged to the second position. It can be discharged via a two-position switching valve. Further, the control valve is constituted by an electromagnetic pressure control valve, and in an operating state of the pressure control valve, for supplying pressure oil from the first valve passage or the third valve passage of the switching valve to the control valve. Opening the fifth valve path, closing the fifth valve path in the non-operating state, and opening the sixth valve path connecting the control valve to the second or fourth valve path of the switching valve. Is formed,
When the control valve is operating, pressure oil from a pilot valve or a pilot hydraulic pressure source can be supplied to the control valve. When the control valve is not operating, pressure oil from the pilot valve can be supplied to the control valve. On the other hand, the switching valve is set at the first position when the operating tool is operated, and is set at the second position when the operating tool is not operated, so that the operating tool is operated. In this state, the pressure oil from the pilot valve can be supplied to the control valve via the switching valve in the first position and the control valve in the operating state. The pressure oil can be supplied to the control valve via the switching valve in the second position and the control valve in the operating state. Further, in a device provided with position forcing means for forcibly positioning the switching valve at the second position irrespective of whether or not the operating tool is operated, the switching valve may be positioned at the second position by the position forcing means. Thereby, the pressure oil from the pilot valve can be supplied to the control valve via the first switching valve and the non-operating control valve. In these devices, the hydraulic actuator is for moving a working unit provided in the working machine, and further, the control unit controls the working unit based on an input signal from a detection unit that detects a posture of the working unit. Determining means for determining whether or not an evasion interference area such as a driver's seat portion provided in the working machine is within a predetermined range;
When it is determined by the determination means that the working unit is approaching a predetermined range with respect to the avoidance interference area, a control command is output to the control valve to control the supply of pilot pressure oil to the control valve. In a device provided with interference prevention control means for preventing the working unit from approaching the further avoidance interference area, the automatic control can be performed by using a control valve necessary for performing the interference prevention control. As a result, it is possible to contribute to the common use of members and simplification of the structure.

[0005]

Next, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2, reference numeral 1 denotes an offset type hydraulic excavator, and the hydraulic excavator 1 includes various components such as a lower traveling unit 2, an upper revolving unit 3, a cab 4, a working unit 5, and the like. The working part 5 includes a rear boom 6 whose base end is supported by the upper swing body 3 so as to be able to swing up and down, a front boom 7 that is supported by the tip of the rear boom 6 so as to be able to swing left and right, and a front boom 7. An arm 8 supported at the tip so as to be able to swing left and right and back and forth, a bucket 9 supported at a tip of the arm 8 so as to be able to swing back and forth, a rear boom cylinder 10 for swinging them, and an offset cylinder The basic configuration such as the configuration including the cylinder 11, the arm cylinder 12, the bucket cylinder 13, and the like is the same as the conventional one.

Each of the cylinders 10 to 13 expands and contracts by the pressurized oil supplied from the main pump 14, but the control of the pressurized oil supply to the cylinders 10 to 13 is the same. One of them will be described as an example of a hydraulic actuator S, and a description will be given based on hydraulic control circuit diagrams shown in FIGS. 3 and 4, 14 is a main pump, 15 is a pilot pump,
16 is an oil tank, 17 is a control valve, 18A is a reduction side pilot valve, 18B is an expansion side pilot valve, 19A is a reduction side switching valve, 19B is an expansion side switching valve,
20A is a reduction side control valve, 20B is an extension side control valve, and 21 is an emergency switching valve.
Is constituted by a pilot-operated three-position switching valve having a contraction-side pilot port 17a and an extension-side pilot port 17b. When the pilot pressure oil is not supplied to the pilot ports 17a and 17b, the control valve 17 is located at the neutral position X where the supply of the hydraulic oil to the hydraulic actuator S is stopped. By supplying the pilot pressure oil to 17a, the pressure oil from the main pump 14 is supplied to the reduction side port Sa of the hydraulic actuator S,
Further, the hydraulic actuator S is located at a contraction position Y where oil from the extension side port Sb of the hydraulic actuator S is discharged to the oil tank 16, and the pilot pressure oil is supplied to the extension side pilot port 17b.
Is arranged at an extended position Z for supplying pressure oil from the main pump 14 and discharging oil from the hydraulic actuator reduction side port Sa to the oil tank 16.

Further, the pilot valves 18A, 18
B, switching valves 19A, 19B, control valves 20A, 20B
A reduction side and an extension side are provided, respectively. However, since they are the same, when describing the reduction side, the reduction side pilot valve 18A includes a pilot port 18a connected to the pilot pump 15, It has a tank port 18b connected to the oil tank 16, and an output port 18c connected to a second port 19b of a reduction side switching valve 19A described later. When the operating tool 22 for the hydraulic actuator S disposed in the cab 4 is operated to the neutral position or the extension side, the output port 18c of the reduction-side pilot valve 18A communicates with the tank port 18b. However, when the operating tool 22 is operated to the reduction side, the output port 18c communicates with the pump port 18a, whereby the output port 18c
From the pilot pressure oil. Here, the pressure of the pilot pressure oil output from the output port 18c increases or decreases according to the operation amount of the operation tool 22.

Further, the reduction side switching valve 19A is a five-port two-position switching valve, the first port 19a is connected to the oil tank 16, the second port 19b is connected to the output port 18c of the reduction side pilot valve 18A, The third port 19c is connected to the pilot pump 15, the fourth port 19d is connected to a first port 20a of a reduction side control valve 20A described later, and the fifth port 19e is connected to a second port 20b of the reduction side control valve 20A. . The reduction side switching valve 19A is provided with first and second pilot ports 19f and 19g. The first pilot port 19f is connected to the reduction side pilot valve output port 18c and the reduction side switching valve second port 19b. The pilot pressure oil is supplied to the first pilot port 19f in accordance with the output of the pilot pressure oil from the reduction side pilot valve 18. The second pilot port 19g is connected to an emergency switching valve 21 described later.
Is connected to the output port 21c. When the pilot pressure oil is not supplied to both pilot ports 19f and 19g, the reduction side switching valve 19A is used for the
The first port 19a is closed by the biasing force of (1), and a valve path (a valve path corresponding to the second valve path of the present invention, hereinafter referred to as a second valve path 19i) connecting the second port 19b and the fourth port 19d.
) Is opened, and a valve path from the third port 19c to the fifth port 19e (a valve path corresponding to the third valve path of the present invention, hereinafter referred to as a third valve path 19j) is opened. It is located at the position Y, communicates the reduction-side pilot valve output port 18c with the reduction-side control valve first port 20a, and supplies pilot pressure oil from the pilot pump 15 to the reduction-side control valve second port 20b. It has become. When the pilot pressure oil is supplied to the first pilot port 19f, the third port 19c is closed,
A valve path from the second port 19b to the fifth port 19e (a valve path corresponding to the first valve path of the present invention, hereinafter referred to as a first valve path 19k) is opened, and the fourth port 19d is connected to the first port 19d. By switching to a first position X where a valve path (a valve path corresponding to the fourth valve path of the present invention, hereinafter referred to as a fourth valve path 19m) leading to the port 19a is opened, the reduction-side pilot valve output port 18c is opened. Is supplied to the reduction-side control valve second port 20b, and the oil from the reduction-side control valve first port 20a is discharged to the oil tank 16. Further, when the pilot pressure oil is supplied to the second pilot port 19g, the pressure of the pilot pressure oil and the urging force of the elastic machine 19h determine whether the pilot pressure oil is supplied to the first pilot port 19f. Regardless, the reduction side switching valve 19A is located at the second position Y.

The reduction side control valve 20A includes
An electromagnetic proportional pressure-reducing valve having third ports 20a, 20b, 20c and a solenoid 20d.
Reference numeral 0a is connected to the fourth port 19d of the reduction side switching valve, second port 20b is connected to the fifth port 19e of the reduction side switching valve, and third port 20c is connected to the reduction side pilot port 17a of the control valve 17. In a non-operating state in which the solenoid 20d is not excited, the reduction side control valve 20A is a valve path that connects the first port 20a and the third port (a valve path corresponding to the sixth valve path of the present invention). (Hereinafter, referred to as a sixth valve path 20e) and the second port 20b is closed, but when the solenoid 20d is excited based on an operation command from the control unit 23 described later, the second port 20b is closed. It is configured to open a valve path (a valve path corresponding to the fifth valve path of the present invention, hereinafter referred to as a fifth valve path 20f) communicating with the third port 20c. Then, by opening the fifth valve path 20f,
The pilot pressure oil from the first valve path 19k or the third valve path 19j is output from the fifth valve path 20f and supplied to the control valve reduction side pilot port 17a. The output pressure from 20f is
The value increases or decreases in response to a control command output from the control unit 23 to the drive circuit of the solenoid 20d.

Further, the emergency switching valve 21 includes a tank port 21a, a pump port 21b, and an output port 21c.
And a solenoid-operated two-position switching valve provided with a solenoid 21d, wherein the tank port 21a is connected to the oil tank 16, the pump port 21b is connected to the pilot pump 15, and the output port 21c is connected to the second pilot port of the reduction-side switching valve 19A. 19g. When the solenoid 21d is not excited, the emergency switching valve 21 is located at the normal position X where the valve path from the output port 21c to the tank port 21a is opened, and the reduction-side switching valve second pilot port 19g is opened. Is discharged to the oil tank 16. When the emergency switch 29, which will be described later, is turned on, the solenoid 21d is excited, so that the pump port 21b is connected to the output port 21.
It is configured to switch to the emergency position Y in which the valve path to c is opened to supply the pilot pressure oil from the pilot port 15 to the reduction-side switching valve second pilot port 19g.

On the other hand, the control section 23 is constituted by using a microcomputer or the like, and includes a boom angle sensor 24 for detecting a relative angle of the rear boom 6 with respect to the upper swing body 3, a front boom. 7, an offset angle sensor 25 for detecting a relative angle with respect to the rear boom 6, an arm angle sensor 26 for detecting a relative angle of the arm 8 with respect to the front boom 7, and a bucket angle sensor 2 for detecting a relative angle of the bucket 9 with respect to the arm 8.
7. A reduction pressure sensor 28A for the rear boom, which detects a pressure in a pilot oil passage connecting the reduction side pilot valve output port 18c of the pressure oil supply circuit of the rear boom cylinder 10 and the reduction side switching valve second port 19b, an extension side. Rear boom extension side pressure sensor 28B for detecting the pressure of the pilot oil passage connecting the pilot valve output port 18c and the extension side switching valve second port 19b, similarly, the offset cylinder 11, the arm cylinder 12, the bucket cylinder 13 pressure sensor 28A and extension pressure sensor 28 for offset, arm, and bucket provided in each pressure oil supply circuit (not shown) of FIG.
B, and signals from various sensors and switches, such as a mode selection switch 30 to be described later, are input. Based on these input signals, the rear boom cylinder 10, the offset cylinder 11, the arm cylinder 1
2. For the rear boom, offset, arm, etc. provided in each pressure oil supply circuit of the bucket cylinder 13,
Each reduction-side control valve 20A and extension-side control valve 20 for the bucket
A control command is output to B or the like. Here, the pressure sensors 28A and 28B detect by the control unit 23 when the operating tool 22 of the corresponding hydraulic actuator S is operated and the pilot pressure oil is output from the output port 18c of the pilot valves 18A and 18B. It is set to output a signal. Further, the mode selection switch 30 is a switch for selecting one of the “manual mode” and the “auto mode”. When the “manual mode” is selected, the rear boom 6 and the front boom The operation of the arm 7, the arm 8, and the bucket 9 is performed based on the operation of the corresponding operating tool 22, respectively. On the other hand, when the “automatic mode” is selected, for example, the arm 8 and the bucket 9 are automatically swung so that soil and the like mounted on the bucket 9 do not spill when the rear boom 6 is swung. Can be automatically controlled.

The emergency switch 29 is a switch that is turned on in an emergency when the control valves 20A and 20B and the control unit 23 do not operate due to some abnormality, and is normally set to OFF. I have. On the other hand, the circuit connecting the solenoid 20d of the control valves 20A and 20B and the control unit 23 is provided with switch contacts 40A and 40B, respectively.
0A and 40B are set to be closed when the emergency switch 29 is turned off, but are opened when the emergency switch 29 is turned on. A circuit connecting the solenoid 21d of the emergency switching valve 21 and the power supply is provided with a switch contact 41. The switch contact 41 is provided when the emergency switch 29 is turned off.
It is open at F, but the emergency switch 29 is
It is set to be closed based on N operations. That is, when the emergency switch 29 is OFF, the control valves 20A and 20B are controlled by the solenoid 20d by the control unit 2.
3 and operates based on a control command from the control unit 23. However, when the emergency switch 29 is ON, the connection with the control unit 23 is disconnected and the inactive state is maintained. Has become. When the emergency switch 29 is OFF, the emergency switching valve 21 is connected to the solenoid 20d.
Is in the non-energized state and is not excited, and is located at the normal position X described above. However, when the emergency switch 29 is turned on, the solenoid 21d is energized to be in the excited state. Switching to Y is performed.

Next, the control procedure in the control unit 23 will be described with reference to the flowchart shown in FIG. 6. First, the control unit 23 sets the mode selection switch 30 to either "manual mode" or "auto mode". Determine if there is. When the “manual mode” is selected, the process proceeds to a subroutine for manual control. When the “automatic mode” is selected, the process proceeds to a subroutine for automatic control. The manual control and the automatic control are executed when the emergency switch 29 is set to OFF.

In the manual control, the control unit 23 performs an interference prevention control for preventing the working unit 5 from interfering with the cab 4. This interference prevention control will be described with reference to a block diagram shown in FIG. 7 taking manual control on the reduction side of the hydraulic actuator S as an example. First, the control unit 23 includes a boom angle sensor 24, an offset angle sensor 25, an arm angle sensor 26 The attitude calculator 31 calculates the attitude (position) of the working unit 5 based on the detection signal from the bucket angle sensor 27. On the other hand, in the memory 23a of the control unit 23, the interference set as the working unit 5 is set to be no more close to the cab (in the present embodiment, the cab corresponds to the evasion interference area of the present invention) 4. The prevention area H is stored. The control unit 23 compares the posture of the working unit 5 calculated by the posture calculator 31 with the interference prevention area H stored in the memory 23a by the comparison calculator 32, and compares the calculation result with the first signal. Output to the generator 33.
The first signal generator 33 is provided with the comparison arithmetic unit 32
When it is calculated that the working unit 5 is separated from the interference prevention area H by a predetermined distance or more, a signal of 100% is output,
When it is calculated that the work unit 5 has entered the interference prevention area H, a 0% signal is output. When it is calculated that the work unit 5 is located at an intermediate position, the work unit 5 is prevented from interfering. 0 to 100 set to be smaller as approaching the region H
Outputs a signal in the range of%. Further, the signal output from the first signal generator 33 is supplied to a first signal selector (MIN).
34. On the other hand, reference numeral 35 denotes a second signal generator to which a detection signal from the reduction side pressure sensor 28A is input. When the detection signal from the pressure sensor 28A is not input, the second signal generator 35 outputs the first signal selector (MIN).
When a 0% signal is output to the first signal selector 34 and a detection signal is input, a 100% signal is output to the first signal selector (MIN) 34. Further, the first signal selector (MIN) 34 selects the smaller one of the input signal from the first signal generator 33 and the input signal from the second signal generator 35, and based on this, selects the smaller one. Side control valve 2
A control command is output to the drive circuit of the 0A solenoid 20d. That is, for example, 100% from the first signal generator 33
Is input and a 0% signal is input from the second signal generator 35, or a 0% signal is input from the first signal generator 33 and a 100% signal is input from the second signal generator 35. When input, the first signal selector (MIN) 34 selects a signal of 0% and outputs the signal to the reduction side control valve 20A.
Outputs a non-operation command to Also, the first signal generator 3
When a signal of 3% to 50% is input and a signal of 100% is input from the second signal generator 35, the first signal selector (MIN) 34 selects a signal of 50% and controls the reduction side. The output pressure from the fifth valve path 20f is 50% of the valve 20A.
An operation command is output so that Further, when 100% signals are input from both signal generators 33 and 35, 10%
A signal of 0% is selected, and an operation command for fully opening the fifth valve path 20f is output to the reduction side control valve 20A.

In the manual control, when the operator operates the operating tool 22 from the neutral position to the reduction side while the working unit 5 is separated from the interference prevention area H of the cab 4 by a predetermined distance or more, the reduction side pilot valve 18A is activated. The pilot pressure oil is output, and accordingly, the pilot pressure oil is supplied to the reduction-side switching valve first pilot port 19f. In this case, as described above, the emergency switching valve 21 is manually controlled.
Is located at the normal position X and does not supply pilot pressure oil to the reduction-side switching valve second pilot port 19g, so the reduction-side switching valve 19A switches to the first position X. As a result, the pilot pressure oil output from the pilot valve 18A passes through the first valve passage 19k of the reduction-side switching valve 19A at the first position X and passes through the second port 2 of the reduction-side control valve 20A.
0b. Further, the output of the pilot pressure oil is detected by the pressure sensor 28A, and in response to the detection signal, the second signal generator 35 outputs a 100% signal. On the other hand, the first signal generator 33 outputs a 100% signal because the working unit 5 is separated from the interference prevention area H of the cab 4 by a predetermined interval or more. As a result, 100% of the signal is selected by the first signal selector (MIN) 34, whereby the control unit 23
, An operation command is output to the reduction side control valve 20A to fully open the fifth valve path 20f. The pilot pressure oil output from the pilot valve 18A passes through the first valve passage 19k of the reduction-side switching valve 19A at the first position X and the fifth valve passage 20f of the reduction-side control valve 20A, and then the control valve 20f. 17 is supplied to the reduction side pilot port 17a,
As a result, the control valve 17 is switched to the contraction position Y, and the hydraulic actuator S contracts. In this case, the fifth valve path 20f of the reduction side control valve 20A
Is fully open, pilot pressure oil having a pressure corresponding to the operation amount of the operation tool 22 is supplied to the control valve reduction side pilot port 17a. On the other hand, when the operating tool 22 is operated to the reduction side and the pilot pressure oil is supplied to the control valve reduction side pilot port 17a, the control valve expansion side pilot port 1
The oil discharged from 7b is supplied to the oil tank 16 via the sixth valve passage 20e of the extension control valve 20B, the second valve passage 19i of the extension switching valve 19B at the second position Y, and the extension pilot valve 18B. Is discharged. That is, when the operating tool 22 is operated to the reduction side, the extension-side pilot valve 18
The output port 18c of B communicates with the oil tank 16,
No pilot pressure oil is output from the output port 18c.
Therefore, the pilot pressure oil is not supplied to the extension side switching valve first pilot port 19f, and the extension side switching valve 19B is located at the second position Y and opens the second valve path 19i.
Further, since the extension side pressure sensor 28B does not detect the output of the pilot pressure oil, the second signal generator 35 outputs a 0% signal. Then, the 0% signal is supplied to the first signal selector (M
IN) 34, whereby the extension side control valve 2
0B, a non-operation command is output and the extension side control valve 2
OB opens the sixth valve path 20e. As described above, the oil discharged from the control valve extension side pilot port 17b is supplied to the sixth valve path 20e of the extension side control valve 20B and the second valve path of the extension side switching valve 19B at the second position Y as described above. 19i, the oil is discharged to the oil tank 16 via a valve path connecting the output port 18c of the extension side pilot valve 18B and the oil tank 16. In such manual control, when the working unit 5 approaches the interference prevention area H of the cab 4, a signal of 0 to 100% is output from the first signal generator 33 as described above, and the signal is the first signal. Selector (MIN) 34
Is selected by As a result, an operation command is output from the control unit 23 to the reduction side control valve 20A so as to output a reduced pressure corresponding to the signal, and the reduced pressure is supplied to the control valve reduction side pilot port 17a. As a result, the operating speed of the hydraulic actuator S is reduced. Further, when the working unit 5 reaches the interference prevention area H of the cab 4, a 0% signal is output from the first signal generator 33, and the 0% signal is selected by the first signal selector (MIN) 34. Is done. In this case, a non-operation command is output from the control unit 23 to the reduction side control valve 20A, and the reduction side control valve 20A closes the fifth valve path 20f. As a result, the supply of the pilot pressure oil to the control valve reduction side pilot port 17a is cut off, and the hydraulic actuator S stops. That is, at the time of manual control, the hydraulic actuator S operates at a speed corresponding to the operation amount of the operating tool 22 in a state where the working unit 5 is separated from the interference prevention area H of the cab 4 by a predetermined distance or more. When approaching the interference prevention area H, the operating speed is reduced, and when the interference prevention area H is reached, the operation speed is controlled to stop, whereby the working unit 5 interferes with the cab 4. Can be prevented automatically.

The above-described interference prevention control is controlled so that the work unit 5 automatically stops when the work unit 5 reaches the interference prevention area H. In such a case, it is also possible to control to automatically move away from the interference prevention area H. For this control, a case where the working unit 5 approaches the interference prevention area H by operating the hydraulic actuator S to the reduction side as an example will be described below. Will be described.
In this control, since the control for the reduction side control valve 20A is performed in the same manner as described above, the description thereof is omitted.
Control of the extension side control valve 20B will be described with reference to a block diagram shown in FIG. That is, the control unit 23
Compares the posture of the working unit 5 calculated by the posture calculator 31 with the interference prevention area H stored in the memory 23a by the comparison calculator 32, and outputs the calculation result to the third signal generator 43. Output. The third signal generator 43 outputs a 0% signal when the comparison operation unit 32 calculates that the working unit 5 is separated from the interference prevention area H by a predetermined distance or more. Is the interference prevention area H
When it is calculated that the work unit 5 has entered the area, a signal of 100% is output. When it is calculated that the work unit 5 is located at an intermediate position, the signal is set to increase as the working unit 5 approaches the interference prevention area H. A signal in the range of 0 to 100% is output. Further, the signal output from the third signal generator 43 is input to a second signal selector (MIN) 44. On the other hand, reference numerals 45 and 46 denote fourth and fifth signal generators. The fourth and fifth signal generators 45 receive detection signals from the extension-side pressure sensor 28B. When the detection signal from the pressure sensor 28B is not input, the fourth signal generator 45 outputs the second signal selector (MIN) 4
4 outputs a 100% signal to the second signal selector (MIN) 44 when a detection signal is input. On the other hand, the fifth signal generator 46
Outputs a 0% signal to the third signal selector (MAX) 47 when the detection signal from the pressure sensor 28B is not input, and outputs the signal when the detection signal is input.
A signal of 100% is output to the third signal selector (MAX) 47. And the second signal selector (MIN) 44
Then, the smaller one of the input signal from the third signal generator 43 and the input signal from the fourth signal generator 45 is selected, and the selected signal is converted to a third signal selector (MAX) 47.
Output to Further, the third signal selector (MAX) 47 selects the larger one of the input signal from the second signal selector (MIN) 44 and the input signal from the fifth signal generator 46, and selects the selected signal. Based on the signal, in the same manner as in the case of the above-described contraction side control valve 20A, the extension side control valve 20
A control command is output to the drive circuit of the solenoid B 20d. In this case, when the operator operates the operating tool 22 on the extension side (the direction in which the working unit 5 moves away from the interference prevention area H), the third signal generator 43 outputs 0%, 100% according to the position of the working unit 5. % Or 0-100% of the signal, the fourth signal generator 45 outputs a 0% signal, and the fifth signal generator 46 outputs a 100% signal. In this case, first, a 0% signal is selected by the second signal selector (MIN) 44, and then a 100% signal is selected by the third signal selector (MAX) 47. As a result, the control unit 23 sends the extension-side control valve 20
An operation command for fully opening the fifth valve path 20f is output to B. That is, when the operating tool 22 is operated to the extension side, the pilot pressure oil of the pressure corresponding to the operation amount of the operating tool 22 is supplied to the control valve regardless of whether the working unit 5 is away from or close to the interference prevention area H. The hydraulic actuator S is supplied to the extension-side pilot port 17b of the actuator 17 and extends. On the other hand, when the operator operates the operation tool 22 to the reduction side and the working unit 5 approaches the interference prevention area H of the cab 4, a signal of 0 to 100% is output from the third signal generator 43, and The fourth signal generator 45 outputs a 100% signal, and the fifth signal generator 46 outputs a 0% signal. First, the second signal selector (MIN) 44
Selects a signal of 0 to 100%, and then selects a signal of 0 to 100% by a third signal selector (MAX) 47. As a result, the control unit 23 sends the extension-side control valve 20B
In response, an operation command is output to output a reduced pressure corresponding to the signal of 0 to 100% of the third signal generator 43. In this case, since the operating tool 22 is not operated to the extension side, the extension side switching valve 19B is located at the second position Y, and the pilot pressure oil from the pilot pump 15 is supplied to the extension side control valve 20B. The supply of the pilot pressure oil from the pilot pump 15 is the same as in the automatic control described later, and the description is omitted here. On the other hand, since the control for the reduction side control valve 20A is performed in the same manner as described above, the pressure reduced for the reduction side control valve 20A corresponding to the signal of 0 to 100% of the first signal generator 33 is applied. An operation command is output to output. In other words, when the operating unit 22 is operated to the reduction side and the working unit 5 approaches the interference prevention area H of the cab 4, the control valve 17 becomes closer as the working unit 5 approaches the interference prevention area H.
The pilot pressure oil supplied to the contraction side pilot port 17a of the
The pilot pressure oil supplied to b becomes high pressure. Thus, the operating speed of the hydraulic actuator S decreases as the working unit 5 approaches the interference prevention area H, and finally, the working unit 5 automatically operates in a direction away from the interference prevention area H (extended side). Further, the working unit 5 is provided with the interference prevention area H of the cab 4.
, The third signal generator 43 outputs a 100% signal, the fourth signal generator 45 outputs a 100% signal, and the fifth signal generator 46 outputs a 0% signal. Is done. First, the second signal selector (MI
N) 44 selects a 100% signal, and then a third signal selector (MAX) 47 selects a 100% signal. As a result, the control unit 23 sends the extension-side control valve 20B
An operation command to open the fifth valve path 20f fully is output to
Pilot pressure oil is supplied to the extension side pilot port 17b of the control valve. On the other hand, the reduction side control valve 20
A non-operation command is output to A in the same manner as described above, so that pilot pressure oil is not supplied to the reduction side pilot port 17a. Thus, when the working unit 5 reaches the interference prevention area H of the cab 4, the hydraulic actuator S automatically extends, and the working unit 5 is automatically moved away from the interference prevention area H. I have.

Next, the automatic control will be described. In the automatic control, a plurality of routines corresponding to various work contents such as excavation, loading, and transportation are set. Pressure oil supply control to each of the arm and bucket cylinders 10 to 13 is performed. If one hydraulic actuator S of these cylinders 10 to 13 is described as an example, in this case,
Since the operator does not operate the operation tool 22, the output ports 18c of the pilot valves 18A and 18B communicate with the tank port 18b and no pilot pressure oil is output. Therefore, the pilot pressure oil to the switching valve first pilot port 19f is output. And the switching valves 19A and 19B are located at the second position Y. The switching valve 1 at the second position Y
9A and 19B, the second valve path 19i and the third valve path 19j are open as described above. For example, when reducing the hydraulic actuator S, the control unit 23 outputs an operation command to the reduction-side control valve 20A and outputs a non-operation command to the extension-side control valve 20B. As a result, the fifth control valve 20f opens the fifth control valve 20A, and the sixth control valve 20e opens the expansion control valve 20B. Thus, the pilot pressure oil from the pilot pump 15 passes through the third valve path 19j of the reduction-side switching valve 19A at the second position Y and the fifth valve path 20f of the reduction-side control valve 20A, and then flows through the control valve. It is supplied to the reduction side port 17a. In this case, the pressure of the pilot pressure oil supplied to the control valve reduction side port 17a is controlled by the control unit 23 to the reduction side control valve 20.
A increases or decreases in response to the operation command output to A. On the other hand, oil from the control valve extension side port 17b is supplied to the sixth valve path 20e of the extension side control valve 20B, the second valve path 19i of the extension side switching valve 19B at the second position Y, and the output port of the extension side pilot valve 18B. The oil is discharged to the oil tank 16 via a valve connecting the tank port 18b to the tank port 18b.
That is, in the automatic control, the expansion and contraction operation of the hydraulic actuator S is automatically performed by operating the control valves 20A and 20B based on a control command from the control unit 23. Incidentally, in the automatic control, the working unit 5
Of course, it is controlled not to interfere with

In the manual control and the automatic control, for example, the control valve pilot port 1
The supply of pilot pressure oil to 7a, 17b is controlled by control valve 20.
A and 20B are performed via the fifth valve path 20f, and the fifth valve path 20f is connected to the control valves 20A and 20B as described above.
It opens when the solenoid 20d of B is excited. Therefore, if the solenoid 20d is not excited due to a failure of the drive circuit of the control unit 23 or the control valves 20A and 20B, the fifth valve path 20f will not be opened, and even if the operating tool 22 is operated, Even in the automatic control mode, the pilot pressure oil is not supplied to the control valve 17,
The hydraulic actuator S will not operate. In such an emergency, a notification command is output from the control unit 23 to notification means (not shown) such as a lamp, so that the operator can recognize that the control valves 20A and 20B do not operate. In this case, when the emergency switch 29 is turned ON, the solenoid 2 of the emergency switching valve 21 is turned on as described above.
The switch contact 41 provided in the circuit connecting 1d to the power supply is closed, whereby the solenoid 21d is excited to switch the emergency switching valve 21 to the emergency position Y. Further, the control valve 20 is controlled based on the ON operation of the emergency switch 29.
The switch contacts 40A and 40B provided in the circuit connecting the solenoids 20d of the A and 20B and the control unit 23 are opened, whereby the connection between the control valves 20A and 20B and the control unit 23 is cut off, and the control valve 20A , 20B are held inactive.

When the emergency switch 29 is turned ON, the emergency switching valve 21 is located at the emergency position Y as described above, and the pilot pressure oil from the pilot pump 15 is supplied to the switching valve second pilot port 19g. To supply. As a result, the switching valves 19A and 19B are located at the second position Y regardless of the presence or absence of the output of the pilot pressure oil from the pilot valve output port 18c.
9i is open. Further, the control valves 20A and 20B are in a non-operating state, and open the sixth valve path 20e. In this case, for example, when the hydraulic actuator S is reduced, when the operation tool 22 is operated to the reduction side, the pilot pressure oil is output from the reduction side pilot valve output port 18c, and the pilot pressure oil is It is supplied to the control valve reduction side pilot port 17a via the second valve path 19i of the reduction side switching valve 19A at the position Y and the sixth valve path 20e of the reduction side control valve 20A. In this case, the pressure of the pilot pressure oil supplied to the reduction side pilot port 17a increases or decreases in accordance with the operation amount of the operation tool 22. On the other hand, oil from the control valve extension side pilot port 17b is supplied to the sixth valve path 20e of the extension side control valve 20B and the second valve path 1B of the extension side switching valve 19B at the second position Y.
9i, output port 18 of extension side pilot valve 18B
c and a valve path connecting the tank port 18b,
The oil is discharged to the oil tank 16. That is, the emergency switch 29
Is ON, the hydraulic actuator S expands and contracts in response to the operation of the operating tool 22.
In this case, the interference prevention control is not performed.

In the configuration described above, the hydraulic oil control circuit for each hydraulic actuator S of the working unit 5 includes:
Control valve 2 that operates based on a control command from control unit 23
In addition to 0A and 20B, switching valves 19A and 19B are provided that can be switched between a first position X and a second position Y, and the switching valves 19A and 19B are switched to the first position X. In this case, the pressure oil from the pilot valves 18A and 18B can be supplied to the control valve 17 via the control valves 20A and 20B in the operating state. Pressure oil can be supplied to the control valve via the control valves 20A and 20B in the operating state, and the hydraulic oil from the pilot valves 18A and 18B can be controlled via the control valves 20A and 20B in the inactive state. It can also be supplied to the valve 17. The switching valve 19
A and 19B are switched so that the working unit 5 and the cab 4
Manual operation that can operate the hydraulic actuator S corresponding to the operation of the operating tool 22 in a state where the interference prevention control for preventing interference with the hydraulic actuator S is performed. The control section 23 and the control valve 20
In the case where A and 20B fail, the hydraulic actuator S can be operated based on the operation of the operating tool 22.

As a result, even when the control valves 20A and 20B required for performing the interference prevention control during the manual control do not operate due to a failure of the control unit 23 or the drive circuit, the switching valves 19A and 19B are operated. By switching to the second position Y, the hydraulic actuator S can be operated based on the operation of the operating tool 22, and the workability is improved. In addition, automatic control can be performed by effectively using the control valves 20A and 20B.
This can contribute to simplification of the structure.

It should be noted that the present invention is not limited to the first embodiment, and that the emergency switching valve 21 is manually operated to manually switch between the normal position X and the emergency position Y. It can also be. In this case, the emergency switch is not required, but it is necessary to take care that the control valves 20A and 20B do not operate when the emergency switching valve 21 is switched to the emergency position Y. 2
The switch contacts 40A and 40B may be opened based on the detection that 1 has been switched to the emergency position Y.

Further, according to the present invention, as in the second embodiment shown in FIG. 9, the position of the switching valve can be switched based on a command from the control unit. In the second embodiment, the control valve 17, the pilot valves 18A and 18B, the control valves 20A and 20B
B, switch contacts 40A, 40B, pressure sensor 28A,
28B is the same as that of the first embodiment, so that the description is omitted and the same reference numerals are given. In the second embodiment, the switching valves 36A, 36B
Are the same first, second, third, and fourth valve paths 36k, 36i, 36 as the switching valves 19A, 19B of the first embodiment.
j, 36m, which is a solenoid 36n
The solenoid-operated two-position switching valve includes a solenoid de-energization and an excitation command output from the control unit to switch between the second position Y and the first position X. The control unit outputs a control command to the switching valves 36A and 36B so as to be located at the first position X when the detection signals of the pressure sensors 28A and 28B are input during the manual control. Sometimes, the second position Y
The control command is outputted so as to be located at the position.
On the other hand, a circuit connecting the solenoid 36n of the switching valves 36A and 36B and the control unit has switch contacts 42A and 42B.
B, and the switch contacts 42A, 42B
Is set to be closed when the emergency switch is OFF, but to be opened when the emergency switch is turned ON. Thereby, the switching valve 36
A and 36B indicate that when the emergency switch is OFF, the solenoid 36n is connected to the control unit and switches between the first position X and the second position Y based on a control command from the control unit. When the hour switch is ON, the connection with the control unit is disconnected and the switch is held at the second position Y. Thus, the switching valves 36A and 36B perform the same operation as the switching valves 19A and 19B of the first embodiment. The same effect as that of the embodiment is exerted.

[Brief description of the 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 right and left.

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

FIG. 4 is a hydraulic control circuit diagram when a reduction operation is performed during manual control.

FIG. 5 is a block diagram showing input and output of a control unit.

FIG. 6 is a flowchart illustrating a control procedure of a control unit.

FIG. 7 is a block diagram illustrating a control procedure of interference prevention control.

FIG. 8 is a block diagram illustrating a control procedure of interference prevention control according to another embodiment.

FIG. 9 is a hydraulic control circuit diagram of a hydraulic actuator showing a second embodiment.

FIG. 10 is a hydraulic control circuit diagram of a hydraulic actuator showing a conventional example.

[Explanation of symbols]

 4 Cab 5 Working part 17 Control valve 18A Reduction side pilot valve 18B Extension side pilot valve 19A Reduction side switching valve 19B Extension side switching valve 19k First valve path 19i Second valve path 19j Third valve path 19m Fourth valve path 20A Reduction Side control valve 20B Extension side control valve 20d Solenoid 20f Fifth valve path 20e Sixth valve path 22 Operating tool S Hydraulic actuator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-151603 (JP, A) JP-A-6-81807 (JP, A) JP-A-63-57903 (JP, A) 22070 (JP, B2) WO 96/27741 (WO, A1) (58) Fields investigated (Int. Cl. ⁶ , DB name) F15B 20/00 E02F 3/43 F15B 11/08

Claims (9)

(57) [Claims] 1. A control system for supplying hydraulic oil to a hydraulic actuator.
A pilot-operated control valve for performing
A pilot valve that supplies lot pressure oil, and these pilot valve and control valve are connected
In the pilot oilwayPie with operation tool operation
Lot valve to control valve
Control command from control unit to control output pressure of pilot oil
Do based onWorking machine comprising a control valve
In the hydraulic control circuit, the hydraulic oil from the pilot valve is provided in the pilot oil passage.
Supplied to the control valve via the operating control valve.
The first position where the first valve
Control oil via the inactive control valve.
The second position where the second valve path for supplying to the roll valve is formed
A switching valve that can be switched between andAlong with The switching valve is operated in an emergency when the control valve is deactivated.
Of pilot pressure oil to the control valve
Configuration that can be switched to the second position to allow supply
It has become Hydraulic control circuit of work machine. 2. The switching valve according to claim 1, further comprising
As a means to switch between two positions, the emergency switch
Supply pilot pressure oil in conjunction with the ON operation to open the switching valve.
It is provided with an emergency switching valve for switching to the second position.
Or based on the emergency switch ON operation
The connection with the control unit is disconnected and the switching valve is held at the second position.
Hydraulic control circuit for work machines composed of solenoid-operated switching valves with solenoids . 3. An apparatus according to claim 1 or 2, the switching valve, the supply pressure oil from the pilot hydraulic source in a state switched to the second position via the control valve operating state to the control valve three Hydraulic control circuit of the working machine in which the valve path is formed. 4. The operation according to claim 1 , 2 or 3, wherein the switching valve is provided with a fourth valve path for discharging return oil from the control valve to the oil tank in a state where the switching valve is switched to the first position. Control circuit of the machine. 5. The switching valve according to claim 1 , wherein the switching valve discharges return oil from the control valve to the pilot valve via the second valve path in a state where the switching valve is switched to the second position. Hydraulic control circuit of the working machine configured in. 6. The control valve according to claim 5, wherein the control valve comprises an electromagnetic pressure control valve, and when the pressure control valve is in an operating state, the pressure oil from the first valve passage or the third valve passage of the switching valve. The fifth valve path for supplying the control valve to the control valve is opened, and the fifth valve path is closed in the non-operating state, and the sixth valve for communicating the control valve with the second or fourth valve path of the switching valve. A hydraulic control circuit for a working machine in which a valve path is formed so as to open the valve path. 7. The switching valve according to claim 1 , wherein the switching valve is located at the first position when the operating tool is operated, and the switching valve is in the first position when the operating tool is not operated. Hydraulic control circuit of the work machine set to be located at two positions. 8. The hydraulic control circuit for a working machine according to claim 7 , further comprising a position forcing means for forcibly positioning the switching valve at the second position regardless of whether or not the operating tool is operated. 9. The method of claim 1 , 2 , 3 , 4 , 5 , 6 , 7, or
In 8 , the hydraulic actuator is for moving a working unit provided in the working machine, and the control unit further controls the working unit based on an input signal from a detection unit for detecting a posture of the working unit. Means for judging whether or not the evacuation interference area such as the driver's seat provided in the machine is within a predetermined range, and the judgment means causes the working unit to approach the evacuation interference area within a predetermined range. When it is determined that the control valve is in operation, a control command is output to the control valve to control the supply of pilot pressure oil to the control valve, thereby preventing the work unit from approaching the further interference area. And a hydraulic control circuit of the working machine provided with the means.