JPH10140618A - Operational valve system of power shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide an operational valve system of a power shovel without using a computer and a proportional solenoid valve, to prevent the interference of a working device, and also to reduce the impact at the time of stoppage of the working device. SOLUTION: An operational valve system of a power shovel is provided with a plurality of control valves and a plurality of pilot valves for controlling the operation of the boom and arm of a power shovel. The system is also provided with a fist changeover valve 30 that is operated by an offset sensor 24 arranged between a first control valve and a fist pilot valve, a second changeover valve 32 that is operated by a boom position sensor 26 arranged between a second control valve and a second pilot valve, a third changeover valve 34 that is operated by an arm position sensor 28 arranged between a third control valve and a third pilot valve, a thottling means 36 for the boom that is arranged between the second changeover valve 32 and a thank for regulating the flow of pressure oil to be released to the tank, and a throttling means 38 for the arm that is arranged between the third changeover valve 34 and the tank for regulating the flow of pressure oil to be release to the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavator operating valve system, and more particularly, to a power shovel having a plurality of control valves and a plurality of pilot valves for controlling the operation of a boom and an arm of the shovel. And a valve system for an operation system of a power shovel.

[0002]

2. Description of the Related Art Conventionally, particularly in a power shovel having an ultra-small turning function, a working device including a boom, an arm, a bucket, and the like, which rotates in a vertical direction, can be operated in a state of being offset in a horizontal direction. It has become. For example, there is an apparatus having a function of offsetting a working device including a boom by horizontally rotating a boom that rotates in a vertical direction together with a mounting portion on which the vertical rotation shaft is mounted. According to the ultra-small turning type power shovel, it can be effectively used in a site where there is no space and the turning range is restricted. (Note that a standard type power shovel has only a mechanism for turning the entire upper body including a working device and a cabin, and cannot be suitably used in a site where a turning range is restricted.) In the case of a power shovel, since a boom or the like is offset, the bucket (working device) interferes with the power shovel body depending on the operation of the boom, arm, or the like (working device). That is, although the working range in a state where the vehicle does not turn can be enlarged, there is a problem that the working device easily interferes with the power shovel body including the cabin.

[0003] On the other hand, conventionally, when the offset position of the boom, the vertical rotation position of the boom, and the vertical rotation position of the arm deviate from a predetermined area, they are detected by a sensor. A computer analyzes the signal obtained from the sensor to control the proportional solenoid valve, and the proportional solenoid valve controls the supply of hydraulic oil from the pilot valve to the control valve, so that hydraulic power (oil pressure) Cylinder device, etc.). According to the proportional solenoid valve, the flow rate of the pressure oil can be suitably adjusted by the control signal from the computer, so that the hydraulic power can be gently stopped, and the shock at the time of stopping the working device can be reduced.

Further, according to the system including the computer and the proportional solenoid valve, the computer can calculate the positional relationship between the power shovel body, the boom, and the arm to determine whether or not the positional relationship causes interference. Further, since it is possible to arbitrarily set the operation area of the working device in advance, in a site where the working space is severely restricted, for example, in a working space with a ceiling, in a site where interference with the ceiling is not allowed. , Safety can be improved. The system including the computer and the proportional solenoid valve was originally developed as a standard power shovel system, and was applied to an ultra-small turning type power shovel.

[0005]

However, since the conventional system uses an expensive computer and a proportional solenoid valve, there is a problem that the manufacturing cost cannot be reduced. Generally, a micro-swing type power shovel is small in size, and a computer and a proportional solenoid valve need to be equivalent to a large standard power shovel, which is expensive. Further, in the conventional system, there is an advantage that the operation area of the working device can be freely set in advance, but in reality, the site where the interference between the power shovel body and the working device only needs to be prevented is overwhelming. Therefore, a system using a computer and a proportional solenoid valve often has an excessive function, and in practice, it is often sufficient to provide only the interference prevention function of the device itself.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply that can prevent the work equipment from interfering with the power shovel body at a low cost without using a computer and a proportional solenoid valve, and can reduce the shock when the work equipment is stopped. It is an object of the present invention to provide a valve system for an excavator.

[0007]

The present invention has the following arrangement to achieve the above object. That is, the present invention
A first control valve and a first pilot valve for offsetting the boom, a second control valve and a second pilot valve for rotating the boom, and
A control valve system for a power shovel including a third control valve and a third pilot valve for rotating an arm, wherein a signal is generated when the boom is offset from a predetermined range with respect to a body of the power shovel. An offset sensor, a boom position sensor that generates a signal when the boom rotates vertically and is out of a predetermined range, and a boom position sensor that generates a signal when the arm rotates vertically and is out of a predetermined range. An arm position sensor for generating a signal,
The first control valve and the first pilot valve are provided between the first control valve and the first pilot valve. When the boom is offset, the two are communicated with each other. A first switching valve for shutting off the supply of pressure oil to the control valve and releasing the pressure oil supplied to the first control valve to the tank, and is provided between the second control valve and the second pilot valve. When the boom is rotated, the two are communicated with each other. When a signal from the boom sensor is received, the supply of pressure oil from the second pilot valve to the second control valve is shut off, and the second A second switching valve for releasing the pressurized oil supplied to the control valve to the tank, the third control valve and the third control valve,
It is provided between the pilot valves and communicates the two when the arm is rotated, and supplies the pressure oil from the third pilot valve to the third control valve when receiving a signal from the arm sensor. And a boom provided between the second switching valve and the tank for restricting the flow of the pressure oil released to the tank. And a throttle means provided between the third switching valve and the tank for restricting the flow of pressure oil leaking to the tank.

A boom flow control valve for controlling a flow rate of the pressure oil released to the tank by the boom throttle means;
Since the arm throttle means is a flow control valve for the arm that controls the flow rate of the pressure oil released to the tank, the impact when the rotation of the boom or the arm is stopped can be reliably and suitably mitigated.

Also, a first bypass passage provided to allow communication between the first pilot valve and the first control valve, and a first bypass passage provided to allow communication between the second pilot valve and the second control valve. A second bypass passage, a third bypass passage provided to allow communication between the third pilot valve and the third control valve, and opening and closing the first bypass passage, the second bypass passage, and the third bypass passage. By providing the bypass on-off valve, when the lock state is established due to a failure of the electric system or the like, the lock state can be suitably canceled by opening the bypass on-off valve.

A first block having the first switching valve, a second block having the second switching valve and the boom throttle unit, and a third block having the switching valve and the arm throttle unit are provided side by side. The bypass opening / closing valve is inserted through the first bypass passage, the second bypass passage, and the third bypass passage incorporated in each of the blocks, and is inserted into the insertion hole, and the moving operation is performed. By providing a valve body that simultaneously opens and closes the first bypass passage, the second bypass passage, and the third bypass passage, a highly reliable valve system can be formed compactly.

A drain line provided as a passage for draining oil discharged from the boom throttle means and the arm throttle means to the tank; and a drain line disposed close to the drain line, the relief line being discharged from a hydraulic pump. By providing a tank port line provided as a passage for discharged oil discharged to the tank through a valve or the like, the drain line can be heated by heat of the discharged oil passing through the tank port line, and the boom Of the diaphragm means for the arm and the diaphragm means for the arm can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a circuit diagram of a valve unit 10 of an operation system valve system of a power shovel according to the present invention, and shows a state in which a working device including a boom, an arm, and the like of the power shovel does not operate. A1, A2, and A3 are connected to corresponding pilot valves, and B1, B2, and B3 are connected to corresponding control valves.

As shown in FIG. 2, reference numeral 12 denotes a pilot valve, a first pilot valve 12a for operating the boom offset, a second pilot valve 12b for operating the boom rotation (vertical direction), and an arm rotation. Is provided with a third pilot valve 12c for operating the second pilot valve. Each pilot valve 12a, 12b, 12c is connected to a corresponding pilot valve side communication passage A1, A2, A3, a valve unit 1
0, and the communication passages B1, B2 on the control valve side.
Control valves 16a, 16b, 16 via B3
The pressure oil is generated to the control valve 16 side by operating an operation unit (a lever or the like, not shown) of the pilot valve 12. Reference numeral 18 denotes a hydraulic pump, and reference numeral 20 denotes a tank. Control valve 1
6 is controlled by the pilot valve 12, and when the spool moves to one side, the hydraulic drive device 22 (the boom offset hydraulic cylinder device 22a, the boom rotation hydraulic cylinder device 22b, and the arm rotation hydraulic cylinder device 22c) To the other side, and when moving to the other side, the output of the hydraulic drive device 22 to the other side is generated. Thereby, the boom and the arm of the power shovel are controlled and operated. The valve unit 10 according to the present invention is connected from the pilot valve 12 side by communication paths A1, A2, A3, and from the control valve 16 side by B1, B2, B3. FIG. 2 schematically shows the pipes. For example, the communication paths A1, A2, and A3 are independent pipes (three), but are shown by one line. Also, the valve unit 1
0 may be attached to one side of the control valve 16 that controls the operation of the control valve 16 by the pilot valve 12, and must be attached to the side that controls the operation of the control valve 16 in a direction in which the actuator does not interfere. Absent.

Reference numeral 24 denotes an offset sensor, which generates a signal when the boom is offset from a predetermined range with respect to the base. Note that the boom offset mechanism is not limited to the one that horizontally rotates the mounting portion of the boom as described in the section of the related art, and the boom is divided into two parts, a base-side boom and an arm-side boom. In some cases, the boom on the arm side is offset from the boom on the base side. Accordingly, the mounting position of the offset sensor 24 is between the base and the boom, between the base-side boom and the arm-side boom, and the like. Reference numeral 26 denotes a boom position sensor, which generates a signal when the boom pivots up and down and is positioned outside a predetermined range. Reference numeral 28 denotes an arm position sensor, which generates a signal when the arm rotates vertically and is positioned outside a predetermined range. These sensors may be, for example, limit switches. As a limit switch, for example, if the arm and the boom can be operated,
In the N state, when the arm and the boom are positioned outside the predetermined area, the arm and the boom may be in the OFF state.

Reference numeral 30 denotes a first switching valve, which is provided between the first control valve 16a and the first pilot valve 12a via the communication paths B1 and A1, and communicates with each other when the boom is offset. When receiving a signal from the offset sensor 24, the first switching valve 30 shuts off the supply of pressure oil from the first pilot valve 12a to the first control valve 16a, and
It operates to release the pressure oil supplied to the control valve 16a to the tank 20. The operation is, for example,
This is performed by turning off the power of the first solenoid 31 via a relay switch or the like in accordance with a signal from the offset sensor 24. In FIG. 1, the first solenoid 31 is not energized,
From the pilot valve 12a to the first control valve 1
The state where the supply of the pressure oil to 6a is cut off is shown.

A second switching valve 32 is provided between the second control valve 16b and the second pilot valve 12b via the communication passages B2 and A2, and communicates with each other when the boom is rotated. . Also, the second switching valve 3
2, upon receiving a signal from the boom sensor 26, shuts off the supply of the pressure oil from the second pilot valve 12b to the second control valve 16b, and also releases the pressure oil supplied to the second control valve 16b. Is operated to escape to the tank 20. The operation is performed, for example, by a signal from the boom sensor 26 via a relay switch or the like.
This is done by turning off the power of the solenoid 33. FIG. 1 shows a state in which the second solenoid 33 is not energized and the supply of pressure oil from the second pilot valve 12b to the second control valve 16b is cut off.

Reference numeral 34 denotes a third switching valve, which is provided between the third control valve 16c and the third pilot valve 12c via the communication paths B3 and A3, and connects the two when the arm is rotated. . Further, the third switching valve 34
When the signal from the arm sensor 28 is received, the third
From the pilot valve 12c to the third control valve 1
The supply of the pressure oil to the third control valve 16c is cut off while the supply of the pressure oil to the third control valve 16c is released to the tank 20. The operation is performed by, for example, turning off the power of the third solenoid 35 via a relay switch or the like according to a signal from the arm sensor 28. In FIG.
The state where the third solenoid 35 is not energized and the supply of the pressure oil from the third pilot valve 12c to the second control valve 16c is cut off is shown.

Reference numeral 36 denotes a boom flow control valve, which is an example of a boom throttle means for restricting the flow of pressure oil released to the tank. The boom flow control valve 36 includes a second switching valve 3.
When the pressure oil supplied to the second control valve 16b is released to the tank 20, the pressure oil supplied to the second control valve 16b functions as a shockless valve that controls the flow rate of the pressure oil to reduce the shock. The pressure oil is supplied from the boom flow control valve 36 to the tank 20 to the drain line 19.
Escaped through. Numeral 38 is a flow control valve for the arm, which is an example of a throttle means for the arm for restricting the flow of the pressure oil released to the tank. The arm flow control valve 38 is provided between the third switching valve 34 and the tank 20 to reduce the pressure oil supplied to the third control valve 16c to the tank 20.
When escaping, it acts as a shockless valve that controls the flow rate of the pressure oil to reduce the shock. The pressurized oil is released from the arm flow control valve 38 to the tank 20 via the drain line 19.

Reference numeral 41 denotes a first bypass passage, which is provided so as to allow communication between the first pilot valve 12a and the first control valve 16a via the first switching valve 30.
Reference numeral 42 denotes a second bypass passage, which is provided to allow communication between the second pilot valve 12b and the second control valve 16b via the second switching valve 32. Reference numeral 43 denotes a third bypass passage, which is provided so that the third pilot valve 12c and the third control valve 16c can be communicated via the third switching valve 34. A bypass opening / closing valve 45 opens and closes the first bypass passage 41, the second bypass passage 42, and the third bypass passage 43 at the same time. The bypass on-off valve 45 is opened and closed by a lever 46. However, not limited to the lever 46, a solenoid may be used. In FIG. 1, the bypass on-off valve 45 is in a state where the power shovel operates normally, that is, each bypass passage 4
1, 42 and 43 show the closed state.

According to the operation system valve system of the power shovel having the above-described configuration, the boom or the arm is positioned outside the predetermined region, and one or more of the first to third solenoids 31, 33, and 35 operate. When the operation of the working device is stopped, the normal operation state can be returned by moving the boom or the arm in the opposite direction and positioning it in a predetermined area. That is, when the boom or the arm moves out of the predetermined area (one side), the operation of the control valve 16 in one direction is stopped, but the operation in the other direction is possible. By moving the boom or arm in the opposite direction via hydraulic power by operation of the other side of the spool, the boom or arm can be returned to a normal operating state. When the power to each of the solenoids 31, 33, and 35 is cut off due to a failure in the electric system and the like, and the pilot valves 12a, 12b, and 12c and the control valves 16a, 16b, and 16c are disconnected, the lever 46 is operated. By doing so, the bypass on-off valve 45 is opened. Thereby, each bypass passage 41, 42, 43 can communicate each pilot valve 12a, 12b, 12c and each control valve 16a, 16b, 16c via each switching valve 30, 32, 34. A specific example of bypassing via each of the switching valves 30, 32, 34 will be described later. However, when such bypassing is performed, the boom and the arm can be moved over the entire range including the position that interferes with the power shovel body. It becomes possible to drive, and even if a failure of the electric system or the like occurs, the working device can be temporarily operated.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a sectional view showing one embodiment of the valve unit 10 of the operation system valve system of the power shovel according to the present invention. Fig. 4 shows that the solenoid is OF
It is sectional drawing which shows the state which became F. FIG. 5 is an explanatory diagram illustrating the bypass on-off valve. The valve unit 10
First to third switching valves 30, 32, 34, flow control valves 36, 3
8 and the bypass opening / closing valve 45 are integrally incorporated. Since the first to third switching valves 30, 32, and 34 can have the same structure, only the second switching valve 32 will be described here. Also, the boom flow control valve 36
Since the same structure can be used as the arm flow control valve 38, only the boom flow control valve 36 will be described here.

The second switching valve 32 is a spool type ON / O
FF valve. Reference numeral 50 denotes an input port, and the second pilot valve 12b (hereinafter simply referred to as "pilot valve 1").
2 "), and pressurized oil output from the pilot valve 12 is passed through the communication passage A2 to form an insertion hole 5 serving as an oil chamber.
8 is a port to be introduced. Reference numeral 51 denotes an input connection screw portion, which is provided so as to be connected to a connection member such as a pipe (a joint provided with a filter is shown in FIG. 3).
It communicates with the input port 50. Reference numeral 49 denotes a plug, which is a hole formed at the time of manufacture (not a passage for pressure oil).
Is closed. An output port 52 is connected to a second control valve 16b (hereinafter simply referred to as "control valve 16"), and outputs the pressure oil output from the pilot valve 12 to the control valve 16 via the communication passage B2. Port. Reference numeral 53 denotes an output connection screw portion, which communicates with the output port 52. A tank port 54 communicates with the tank 20 from the drain line 19 via a boom flow control valve 36 described later. In the case of the first switching valve 30, in this embodiment, the tank port 54 is directly connected to the tank without passing through the flow control valve. This is because the boom offset is normally set to be performed at a low speed, and the impact at the time of stopping is small. However, it goes without saying that a flow control valve may be interposed depending on the use conditions.

Numeral 56 denotes a spool, and two constricted portions 5
6a and 56b are formed, and are slidably disposed in the insertion hole 58 in the axial direction. Also, the spool 56
It is always urged by the spring 60 to the right in the drawing. The insertion hole 58 is formed with a hole 62 formed at the left end.
From the drain line 19 through the tank 2 which is a low pressure source
It is connected to 0. Further, both ends of the insertion hole 58 are communicated with each other by a through hole 56 c formed along the axis of the spool 56, and the reciprocation of the spool 56 in the axial direction is restricted by oil filled at both ends of the insertion hole 58. Not receive. The second solenoid 33 is arranged such that the drive shaft portion 33a faces the spring 60 from the right inner end face of the insertion hole 58 so as to be able to advance and retreat into the insertion hole 58. When the second solenoid 33 is energized, the drive shaft portion 33a protrudes. When the drive shaft portion 33a protrudes, as shown in FIG. 3, the spool 56 is pressed, and the spool 56 is moved to the left against the urging force of the spring 60. At this time, the input port 50 is connected to the output port 5 via the first constricted portion 56a of the spool 56.
2 so that the pressure oil of the pilot valve 12 can be supplied to the control valve 16 side.

Next, when the boom is rotated vertically and positioned outside a predetermined range and the boom position sensor 26 generates a signal, the signal is transmitted to the second solenoid 33 via a relay switch or the like in accordance with the signal. Power is turned off. Since the second solenoid 33 is turned off, the spool 56 moves rightward by the urging force of the spring 60, and the drive shaft 33a is drawn into the main body of the second solenoid 33, as shown in FIG. As a result, communication between the input port 50 and the output port 52 is cut off, and the pilot valve 12
The supply of the pressure oil from the control valve 16 to the control valve 16 is shut off. At the same time, the output port 5 is controlled by the second constricted portion 56b.
2 communicates with the tank port 54, and the pressure oil supplied to the control valve 16 is released to the tank 20 via the drain line 19. A boom flow control valve 36 is provided between the tank port 54 of the second switching valve 32 and the tank 20 to control the flow rate of the pressure oil released to the tank 20 to reduce the shock. Unexpected shocking vibration and the like when the operating device stops can be avoided.

Next, an embodiment of the boom flow control valve 36 will be described in detail with reference to FIG. The boom flow control valve 36 has a general shockless valve configuration.
6, a discharge port 68 is opened, and a spool 70 having a fixed throttle 72 and communication holes 73 and 74 for communicating between an oil chamber 64a on the introduction port side and an oil chamber 64b on the discharge port side reciprocates in the oil chamber 64. Movably inserted into its spool 70
Of springs 75, 7 between the oil chamber 64 and the inner wall of the oil chamber 64.
6 has a configuration in which it is loaded. The introduction port 66
During normal operation of the power shovel, the oil chamber 64 communicates with the tank port 54 of the second switching valve 32 via the communication hole 88b and the flow path 78. The discharge port 68 connects the oil chamber 64 and the tank 20 via the drain line 19. A through hole 71 is formed in the spool 70 along the axis, and an orifice (fixed throttle 72) is provided in the middle of the through hole 71. Reference numeral 73 denotes a communication hole on the introduction port side, which is formed so as to communicate with the oil chamber 64a on the introduction port side. A communication hole 74 on the discharge port side is formed so as to communicate with the oil chamber 64b on the discharge port 68 side.

The operation of the shockless valve (boom flow control valve 36) having such a configuration will be described below. First, as shown in FIG. 4, the second switching valve 32 is turned off, the output port 52 communicates with the tank port 54, and the pressure oil supplied to the control valve 16 is supplied to the boom flow control valve. It is supplied to 36 introduction ports 66. The pressure oil flows from the introduction port 66 through the communication port 73 on the introduction port side, the oil chamber 64a on the introduction port side, the fixed throttle 72, the oil chamber 64b on the discharge port side, the communication hole 74 on the discharge port side, and the discharge port 68. Pass through, drain line 1
9 and is discharged to the tank 20 on the low pressure side. In the initial stage when the pressure oil is introduced, a flow of oil flows from the introduction port 66 side to the discharge port 68 side in the fixed throttle 72, so that a differential pressure is generated, and the spool 70 is displaced by the spring 76 on the discharge port side. Move to the discharge port 68 side against the urging force of. As the flow rate increases, the differential pressure increases, and the spool 70 moves further to the discharge port 68 side, and the discharge port 6
The communication hole 74 on the eighth side is closed, and the flow of oil decreases. As a result, the differential pressure generated in the fixed throttle 72 decreases, and the spool 70 moves toward the introduction port 66 by the urging force of the spring 76 on the discharge port 68 side, and the flow of oil increases again. The above operation is repeated within a short time, and the flow rate becomes constant such that the above-mentioned differential pressure and the urging force of the spring on the discharge port 68 side are balanced. Then, even if the pressure of the pressure oil introduced into the introduction port 66 decreases thereafter, the differential pressure across the fixed throttle 72 decreases, and the spool 70
Is returned to the oil chamber 64a on the introduction port side, and the area of the communication hole 74 on the discharge port side that opens to the discharge port 68 is increased, so that the flow rate of the discharged oil is kept substantially constant. As described above, according to the boom flow control valve 36, the oil supplied to the control valve 16 can be slowly and finally flown to the tank 20 at a substantially constant flow rate.

By controlling the flow rate in this way, the second
Even when the supply of pressure oil from the pilot valve 12 to the control valve 16 is suddenly cut off by the switching valve 32, the boom can be slowly operated and stopped. That is, the shock of the stop can be reduced. This effect is similarly obtained by the arm flow control valve 38 for the operation of the arm. Therefore, unexpected shock vibration when the operating device stops can be avoided, and safety can be improved.

In the case of a large power shovel, the amount of oil for operating the control valve 16 increases.
In order to control the predetermined speed, it is necessary to increase the amount of oil released by the flow control valves 36 and 38. In order to cope with the magnitude of the amount of oil flowing from the control valve 16 side to the tank 20 through the flow control valves 36 and 38 depending on the size of the machine, the diameter of the orifice of the fixed throttle 72 may be changed. That is, in the case of a large-sized power shovel, the diameter of the orifice of the fixed throttle 72 may be increased. Therefore, other parts can be shared, and the manufacturing cost can be reduced.

Next, based on FIG.
An embodiment in which the valve unit 10 is formed by integrally incorporating 0, 32, 34, the boom flow control valve 36, and the arm flow control valve 38 will be described. In the embodiment of FIG. 5, the first block 81 having the first switching valve 30 and the second block 81
A second valve having a switching valve 32 and a boom flow control valve 36;
The block 82, the third switching valve 34, and the third block 83 having the arm flow control valve 38 are provided side by side and integrated.

A bypass opening / closing valve 45 has an insertion hole 84 formed through each of the blocks 81, 82, 83.
And a redundant spool 86 that is inserted through the insertion hole 84 and rotates to open and close the first to third bypass passages 41, 42, and 43. Redundant spool 8
6 has communication holes 88a, 88b, 88c corresponding to the first to third bypass passages 41, 42, 43 in which openings at both ends of the passages are provided at 90 ° positions. Therefore, the bypass on-off valve 45 is a rotary on-off valve that opens and closes by rotating the valve body 86 manually (the lever 46, see FIG. 1) or by the power of a solenoid or the like. If the bypass opening / closing valve 45 is provided with three outer peripheral grooves, it may be a spool-type opening / closing valve that opens and closes by reciprocating the valve body manually or by the power of a solenoid or the like. Furthermore, by having the above two opening and closing mechanisms,
For example, it is possible to improve reliability by providing one to operate by power and the other to operate manually. FIG. 5 shows a state in which the bypass on-off valve 45 is closed.

Next, the operation of the bypass on-off valve 45 will be described for the second switching valve 32 in the same manner as described above. When the lever 46 of the redundant spool 86 is operated and set as shown in FIG. 3, when the second solenoid 33 is in the ON state, the pressure oil of the pilot valve 12 apparently passes through the communication passage A2, the input port 50, The air is supplied to the control valve 16 through the second switching valve 32 (in the insertion hole 58), the output port 52, and the communication path B2. This state,
Let it be X communication state. When the boom sensor 26 operates while the redundant spool 86 remains as described above,
When the second solenoid 33 is in the OFF state, the pressure oil supplied to the control valve 16 is
Communication path B2, output port 52, inside second switching valve 32 (in insertion hole 58), tank port 54, communication hole 88b, flow path 7
8. It is supplied to the tank 20 through the boom flow control valve 36 and the drain line 19. This state is called a Y communication state. By entering the Y communication state, the rotating boom can be stopped slowly.

Also, due to a trouble in the electric circuit, the power to the second solenoids 33 on both sides of the pair of valve units 10 and 10 provided on both sides of the control valve 16 is cut off, and the second solenoid 33 is turned off. , The two spools 56 move to the Y-communication state.
And no pressure oil is supplied to both sides. Therefore, in this state, the actuator (here, the boom) cannot operate. At this time, by operating the lever 46 to rotate the redundant spool 86 of the bypass on-off valve 45 as shown in FIG. 7, the pressure oil of the pilot valve 12 is clearly shown in FIG. A state in which the control valve 16 is supplied to the control valve 16 through the second bypass passage 42, the communication passage 88b, the tank port 54, the inside of the second switching valve 32 (the inside of the insertion hole 58), the output port 52, and the communication passage B2. , Z communication state). At this time, communication from the tank port 54 to the boom flow control valve 36 is cut off. Thereby, it becomes possible to operate the actuator (here, the boom). Further, in the case where the spool 56 of the second switching valve 32 is in a transient state and sticks in some state and stops, by operating the redundant spool 86 in the same manner as described above, the operating device (here, Boom) can be activated. However, in order to achieve the above-described state, the second switching valve 32 is provided in a predetermined structure so that the X-communication state or the Z-communication state is established regardless of the position where the spool 56 stops. Needless to say, it is necessary.

Next, the tank port line 80 provided immediately below the drain line 19 as shown in FIGS. As described above, the boom flow control valve 36 and the arm flow control valve 38 communicate with the drain line 19, and the drain line 19
The exhaust oil is returned to the tank 20 through the tank. On the other hand, the tank port line 80 is arranged close to the drain line 19 and is provided as a passage for the discharged oil discharged from the hydraulic pump, discharged through the relief valve or the like, and discharged to the tank 20. . By arranging the tank port line 80 in this manner, the heat of the discharged oil in the tank port line 80 is transferred to the drain line 19.
It can be transmitted to the discharged oil inside. The discharged oil is discharged from the hydraulic pump and is heated. Therefore, the temperature of the discharged oil in the drain line 19 can be increased at a low oil temperature, and the performance of the boom flow control valve 36 and the arm flow control valve 38 can be improved. The relief valve 92 (see FIG. 2) is provided between the hydraulic pump 18 and the pilot valve 12, for example.
Some are provided to keep the pressure of the pressurized oil supplied to the compressor substantially constant.

As described above, according to the present invention, a computer (precision electronic parts) is not required, so that it is hard to break down and easy to handle. Further, since a simple mounting structure is sufficient as compared with a case where a computer is mounted, manufacturing costs can be reduced. In the above embodiment, the boom offset is performed at a low speed, and the first switching valve 30 is not provided with the shockless valve. Are the second switching valve and the third
Needless to say, a shockless valve may be provided similarly to the switching valve. Also, in the above embodiment, the boom flow control valve 36 and the arm flow control valve 38
Although a temperature-guaranteed shockless valve that can be operated even at low temperatures was used, the present invention is not limited to this.
Although the temperature cannot be guaranteed by a simple stop 90 as shown in FIG. 7, the same effect can be obtained. As described above, the present invention has been described in various ways with preferred embodiments.
The present invention is not limited to this embodiment, and it goes without saying that many modifications can be made without departing from the spirit of the invention.

[0035]

According to the present invention, the switching valve (ON / OFF)
By using a combination of a valve and a throttle means (flow control valve, etc.), it is possible to prevent the working device from interfering with the power shovel body without using a computer and a proportional solenoid valve, and to perform work including a boom and an arm. An operation valve system for a power shovel that can reduce an impact when the device is stopped can be provided. Therefore, a significant effect is achieved in that the manufacturing cost of a power shovel having a suitable interference prevention function and a suitable shock absorbing function at the time of stopping can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of an operation system valve system of a power shovel according to the present invention.

FIG. 2 is a circuit diagram illustrating a mounting portion of a valve unit according to the present invention.

FIG. 3 is a sectional view showing one embodiment of the valve unit according to the present invention.

FIG. 4 is a sectional view showing an operation state of the embodiment of FIG. 3;

FIG. 5 is an explanatory diagram illustrating a bypass on-off valve according to the present invention.

FIG. 6 is a sectional view showing a use state of the embodiment of FIG. 3;

FIG. 7 is a sectional view showing another embodiment of the flow control valve according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 Valve unit 24 Offset sensor 26 Boom position sensor 28 Arm position sensor 30 First switching valve 32 Second switching valve 34 Third switching valve 36 Boom flow control valve 38 Arm flow control valve 41 First bypass passage 42 Second bypass Passage 43 Third bypass passage 45 Bypass on-off valve

Claims (5)

[Claims] 1. A first control valve and a first pilot valve for offsetting a boom, a second control valve and a second pilot valve for rotating a boom, and a control valve for controlling operation of a boom and an arm of a power shovel. A control system valve system for a power shovel including a third control valve and a third pilot valve for rotating an arm, wherein a signal is output when the boom is offset from a predetermined range with respect to the base of the power shovel. An offset sensor that is generated, a boom position sensor that generates a signal when the boom rotates vertically and is out of a predetermined range, and a boom position sensor that generates a signal when the arm is rotated vertically and is out of a predetermined range An arm position sensor for generating a signal to the first control valve and the first pilot valve; And when the boom is offset, the two are communicated with each other, and when receiving a signal from the offset sensor, the supply of pressure oil from the first pilot valve to the first control valve is shut off. A first switching valve for releasing pressurized oil supplied to the first control valve to the tank; and a second switching valve provided between the second control valve and the second pilot valve. When the signal from the boom sensor is received, the supply of the pressure oil from the second pilot valve to the second control valve is shut off, and the pressure oil supplied to the second control valve is supplied to the tank. A second switching valve which is provided between the third control valve and the third pilot valve. When receiving a signal from the arm sensor, the supply of pressure oil from the third pilot valve to the third control valve is shut off, and the pressure oil supplied to the third control valve is released to the tank. A third switching valve; a boom throttling means provided between the second switching valve and the tank to regulate the flow of pressure oil escaping to the tank; a boom throttle means provided between the third switching valve and the tank; An operating valve system for a power shovel, comprising: a throttle means for an arm for regulating a flow of pressure oil to be released. 2. A boom flow control valve for controlling the flow rate of pressure oil released by the boom throttle means to the tank, and the arm flow control valve for controlling the flow rate of pressure oil released by the arm throttle means to the tank. 2. The method according to claim 1, wherein
An operating valve system for the power shovel as described. 3. A first bypass passage provided to allow communication between the first pilot valve and the first control valve, and a first bypass passage provided to allow communication between the second pilot valve and the second control valve. A second bypass passage; a third bypass passage provided to allow communication between the third pilot valve and the third control valve; and opening and closing the first bypass passage, the second bypass passage, and the third bypass passage. 3. The valve system according to claim 1, further comprising a bypass valve. 4. A first block having the first switching valve,
A second valve having the two-way switching valve and the boom throttle means;
A third block having a block, the switching valve, and the throttle means for the arm is provided side by side,
An insertion hole formed to penetrate the first bypass passage, the second bypass passage, and the third bypass passage incorporated in each of the blocks; and a first bypass passage inserted through the insertion hole and moved by a moving operation. 4. The valve system according to claim 3, further comprising a valve body for simultaneously opening and closing the second bypass passage and the third bypass passage. 5. A drain line provided as a passage for draining oil discharged from the boom throttle means and the arm throttle means to the tank, and a relief line disposed close to the drain line and discharged from a hydraulic pump. 5. The valve system for an operation system of a power shovel according to claim 1, further comprising a tank port line provided as a passage for discharged oil discharged to a tank through a valve or the like.