JP3136118B2 - Hydraulic operation valve system and power shovel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulically operated valve system and a power shovel, and more particularly to a hydraulically operated valve system and a control valve and a pilot valve for controlling the operation of a hydraulic device. The present invention relates to a power shovel including the hydraulic operation system valve system.

[0002]

BACKGROUND ART Hydraulic operating system valve system, when controlling the operation of the hydraulic device, for example, the operation to prevent interference with other members when the operating portion of the hydraulic system is activated to outside the predetermined range of positions It is used when automatically stopping the operation of the unit. As such a hydraulically operated valve system, for example, there is a system used for a power shovel having a super turning function. The power shovel having the ultra-small turning function is configured such that a working device including a boom, an arm, a bucket, and the like, which rotates in a vertical direction, can be operated while being offset in a horizontal direction.
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. (In the case of a standard type power shovel, there is only a mechanism for turning the entire upper body including the working device and the cabin, and it cannot be suitably used in a site where the 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 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, it is possible to determine whether or not the positional relationship between the power shovel main body, the boom and the arm is calculated by the computer and 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.
This is applied to a micro turning power shovel.

However, this conventional system has a problem that the manufacturing cost cannot be reduced because an expensive computer and a proportional solenoid valve are used. 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.

Therefore, an alternative technology (hereinafter referred to as "background technology") having a configuration as shown in FIGS. 11 and 12 can be proposed. This background art is characterized in that a computer and a proportional solenoid valve are not used, and the configuration thereof will be described below. FIG. 11 shows a hydraulic operating valve system (operating valve system of a power shovel) according to the background art.
FIG. 2 is a circuit diagram of the valve unit 10 of FIG. 1, showing a state in which a working device including a boom and an arm of a 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. 12, reference numeral 12 denotes a pilot valve, a first pilot valve 12a for operating a boom offset, a second pilot valve 12b for operating a boom (up and down 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 communication paths B1, B2, B on the control valve side
3, control valves 16a, 16b, 16c
, And generates hydraulic oil toward the control valve 16 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 16
Is controlled by the pilot valve 12, and when the spool moves to one side, the hydraulic drive device 22 (boom offset hydraulic cylinder device 22a, boom pivot hydraulic cylinder device 22b, arm pivot hydraulic cylinder device 22c) An output to one side is generated, and when moving to the other side, an output to the other side of the hydraulic drive device 22 is generated. Thereby, the boom and the arm of the power shovel are controlled and operated. And this valve unit 10
From the pilot valve 12 side, the communication paths A1, A2,
By A3, B1 from the control valve 16 side,
They are connected by B2 and B3. FIG. 12 schematically shows a pipe, for example, communication paths A1, A2,
A3 is an independent conduit (three), which is indicated by a single line. In addition, the valve unit 10 may be attached to one side of the pilot valve 12 that controls the operation of the control valve 16. Need not be installed.

An offset sensor 24 generates a signal when the boom is offset from a predetermined range with respect to the base. In addition, the boom offset mechanism is not limited to the one described above, in which the mounting portion of the boom is rotated in the horizontal direction, and the boom is divided into two parts, a boom on the base side and a boom on the arm side. There is one that offsets the boom on the arm side with respect to the boom. Therefore,
The mounting position of the offset sensor 24 is between the base and the boom, or between the base-side boom and the arm-side boom. 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. Also, 28 is the arm position sensor, the arms generates a signal when the rotated vertically located outside a predetermined range. These sensors may be, for example, limit switches. The limit switch may be, for example, an ON state when the arm and the boom are operable, and an OFF state when the arm and the boom are positioned outside a predetermined area.

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 passages B1 and A1, and communicates with each other when the boom is offset. Also, the first switching valve 30
When receiving a signal from the offset sensor 24,
The supply of the pressure oil from the first pilot valve 12a to the first control valve 16a is shut off, and the pressure oil supplied to the first control valve 16a is removed from the tank 20.
It works to escape. The operation is performed by, for example, turning off the power of the first solenoid 31 via a relay switch or the like according to a signal of the offset sensor 24. In FIG. 11, the first solenoid 31 is not energized and the first pilot valve 12a to the first control valve 16a
This shows a state in which the supply of pressure oil to the oil supply is cut off.

Reference numeral 32 denotes a second switching valve, which 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 rotating the boom. Also, the second switching valve 32
When a signal from the boom sensor 26 is received, the second control valve 16b
The operation of shutting off the supply of the pressure oil to the tank 20 and releasing the pressure oil supplied to the second control valve 16b to the tank 20 is performed. The operation is performed, for example, by the boom sensor 2
This is done by turning off the power of the second solenoid 33 via a relay switch or the like in accordance with the signal of No. 6. FIG. 11 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 passages B3 and A3, and connects the two when the arm is rotated. Further, when receiving the signal from the arm sensor 28, the third switching valve 34 cuts off the supply of the pressure oil from the third pilot valve 12c to the third control valve 16c, and also transmits the third control valve 16c to the third control valve 16c. It operates to release the supplied pressure oil to the tank 20. The operation is performed by, for example, the arm sensor 28
This is done by turning off the power of the third solenoid 35 via a relay switch or the like in accordance with the signal (3). In FIG. 11, the third
When the solenoid 35 is not energized, the third pilot valve 1
The state where the supply of the pressure oil from 2c 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. 11, 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 power valve system for 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 are operated. 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. the boom and arm by actuation of the other side of the spool and moving in the opposite direction through the hydraulic power can be returned to the boom and arm to the 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, and 34 will be described later. However, when such bypassing is performed, the boom and the arm are 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.

According to the above configuration, the switching valve (ON / OF)
By using a combination of the F valve) and the 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 include a boom and an arm. it can be provided excavators operation system valve system that can reduce impact when <br/> stop working device. Therefore, 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.

[Problems to be solved by the invention]

However, in the configuration of the background art described above, the fluidity of the oil decreases at low temperatures, so that the pressure oil flows properly through the throttle means such as the boom flow control valve 36 and the arm flow control valve 38. Can not do. Therefore, when the operating parts such as the boom and the arm are located outside the predetermined range, the state becomes the same as the state where the switching valves such as the second switching valve 32 and the third switching valve 34 are not operating, and
The operation of the operation unit cannot be stopped, and may eventually interfere with the cabin or the like. That is, according to the power shovel of the background art, in the interference prevention function of the boom and the arm (attachment), the shock mitigation function is controlled by the flow control valve. However, due to the viscosity problem, the control flow rate becomes small, and the attachment does not stop, which is dangerous. As a safety measure, the switching valve, which is an electromagnetic valve for preventing interference, is controlled by a temperature sensor so that the coil does not operate unless the oil temperature reaches a predetermined temperature (for example, + 10 ° C.). Conceivable. However, this method requires a warm-up operation in a cold region, and there is a problem that the operation cannot be immediately performed for an excavation operation or the like using a hydraulic shovel.

[0017] Therefore, an object of the present invention can inexpensively manufactured without using a computer as the proportional solenoid valve, automatically stopped when the operation unit is operated outside a predetermined position range, the operation portion is stopped It is an object of the present invention to provide a hydraulic operation system valve system that can reduce the shock at the time of the operation and can appropriately operate the automatic stop function of the operation unit and appropriately operate the hydraulic device even when the oil temperature is low.

[0018]

The present invention has the following arrangement to achieve the above object. That is, the present invention
In a hydraulically operated valve system configured with a control valve and a pilot valve to control the operation of the hydraulic device, a position sensor that generates a signal when an operating unit of the hydraulic device is operated outside a predetermined set position range. ,
Provided between the control valve and the pilot valve, when operating a hydraulic device, they communicate with each other,
Upon receiving a signal from the position sensor, while shutting off the supply of pressure oil from the pilot valve to the control valve, a switching valve for releasing the pressure oil supplied to the control valve to a tank, Throttling between the switching valve and the tank to regulate the flow of pressure oil that escapes to the tank
Is provided as a means to reduce the flow rate of pressure oil
Flow that can be controlled at a constant
The quantity control valve and the temperature of the oil in the hydraulic circuit of the hydraulic device.
A temperature sensor for detecting the temperature, and a signal from the temperature sensor.
When the temperature is lower than a predetermined temperature, the flow control valve is closed.
So that the oil can escape from the switching valve to the tank
And an iris release means that operates .

The flow control valve has an inlet port connected to the switching valve side and a discharge port connected to the tank side opened in the oil chamber. A spool provided with a fixed throttle that communicates between the chamber and the oil chamber on the discharge port side is reciprocally inserted. When the spool moves to the oil chamber on the discharge port side, the opening becomes smaller and it is introduced in reverse. When moving to the oil chamber on the port side, the opening becomes large and a communication hole for communicating the pressure oil passing through the fixed throttle is provided, and when the spool moves largely to the oil chamber on the introduction port side, A communication means for communicating the introduction port and the discharge port without passing through the fixed throttle is provided, and a spring on the introduction port side elastically mounted in the oil chamber on the introduction port side in contact with an end of the spool on the introduction port side. And the discharge port A discharge port-side spring which is elastically mounted in contact with the end of the spool on the discharge port side in the oil chamber on the side of the port, and wherein the throttling release means moves the spool in the oil chamber on the discharge port side according to the moving direction of the spool. The piston is inserted reciprocally in the same direction and receives the spring on the discharge port side, and the pressure oil is introduced into the end of the oil chamber on the discharge port side to move the piston through the movement of the piston. A piston driving means for largely moving the spool to the introduction port side oil chamber against the urging force of the port side spring, whereby the operating part of the hydraulic device is stopped.
Thus, it is possible to reliably and suitably alleviate the impact at the time of operation, and it is possible to suitably obtain a hydraulically operated valve system that can suitably cope with low temperatures.

The present invention also provides a first control valve and a first pilot valve for offsetting the boom, and a second control valve and a second control valve for rotating the boom for controlling the operation of the boom and the arm of the excavator. In a power shovel provided with a hydraulically operated valve system having two pilot valves, a third control valve for rotating the arm, and a third pilot valve,
An offset sensor that generates a signal when the boom is offset from a predetermined range with respect to the base of the power shovel, and a boom that generates a signal when the boom is rotated vertically and positioned outside the predetermined range. A boom provided between the first control valve and the first pilot valve, and a position sensor, an arm position sensor that generates a signal when the arm rotates vertically and is positioned outside a predetermined range, and When offsetting, the two are communicated. When a signal from the offset sensor is received, the supply of pressure oil from the first pilot valve to the first control valve is shut off and the supply of pressure oil to the first control valve is performed. A first switching valve for releasing the pressurized oil 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 interrupted, and the supply of the pressure oil to the second control valve is performed. A second switching valve that releases pressurized oil to the tank, and a second switching valve that is provided between the third control valve and the third pilot valve. A third switching valve that shuts off the supply of pressure oil from the third pilot valve to the third control valve and releases the pressure oil that has been supplied to the third control valve to the tank; Throttle between the switching valve and the tank to regulate the flow of pressure oil that escapes to the tank
Is provided as a pressure reducing means to reduce the flow rate of pressure oil
Controlled to keep constant and operable at low temperatures
Between the boom flow control valve and the third switching valve and the tank
As a throttle means to regulate the flow of pressurized oil that escapes to the tank
Is provided to keep the flow rate of pressure oil released to the tank approximately constant.
Arm flow that can be controlled and operated even at low temperatures
A control valve, a temperature sensor for detecting the temperature of the oil according to the hydraulic circuit of the hydraulic device, in response to a signal from the temperature sensor, in the following Jo Tokoro temperature, the boom flow control
A boom stop release means for actuating the valve from the bypass to the second switching valve so as to release the pressure oil to the tank, in response to a signal from the temperature sensor, in the following Jo Tokoro temperature, for the arm Arm throttle release that operates so as to release pressure oil from the third switching valve to the tank by bypassing the flow control valve
There is also a power shovel characterized by comprising means .

The flow control valve is connected to the oil chamber by the switching.
An introduction port connected to the valve side and a connection to the tank side
The discharge port is opened, and the oil chamber is
A fixed throttle is provided to allow communication between the oil chamber of
The spool is inserted reciprocally and the spool is
When the oil moves to the oil chamber on the discharge port side, the opening becomes smaller.
When it moves to the oil chamber on the introduction port side,
A communication that communicates pressure oil that has increased and has passed through the fixed throttle
A through hole is provided, and the spool is
When moving greatly to the oil chamber, connect the introduction port and the discharge port.
A communication means for communicating without passing through the fixed aperture is provided.
It is the introduction port of the spool in the oil chamber of the introduction port side
The split on the introduction port side, which is mounted on the end of the
And discharge of the spool into the oil chamber on the discharge port side.
A discharge port-side switch that is abutted against the output port end
And a throttle releasing means, wherein the discharge port
Reciprocating in the same direction as the spool moves in the oil chamber on the side
And the spring on the discharge port side
Receiving piston and the end of the oil chamber on the discharge port side.
The introduction of oil leads to the introduction through the movement of the piston.
The spool against the urging force of the spring on the entry port side
Drive the piston to move it to the oil chamber on the introduction port side.
Movement means, the rotation of the boom or arm
The shock at the time of stopping can be reliably and suitably reduced.
Hydraulically operated valve system that can be suitably used at low temperatures
Can be suitably obtained.

Further, 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 on-off valve,
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 movement operation. By providing a valve body that opens and closes the second bypass passage and the third bypass passage at the same time, a highly reliable valve system can be formed compactly.

Also, 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 in close proximity to the drain line and 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 Performance of the diaphragm means for arm and the diaphragm means for arm can be improved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to FIG. FIG. 1 is a circuit diagram showing an embodiment of a hydraulic operation system valve system configured with a control valve 16 and a pilot valve 12 to control the operation of a hydraulic device. Reference numeral 260 denotes a position sensor, which generates a signal when the operating unit of the hydraulic device operates outside a predetermined set position range. Reference numeral 320 denotes a switching valve, which includes the control valve 16 and the pilot valve 1.
2 when operating the hydraulic device,
When the signal from the position sensor 260 is received, the supply of the pressure oil from the pilot valve 12 to the control valve 16 is shut off, and the pressure oil supplied to the control valve 16 is discharged to the tank. Escape to

Reference numeral 360 denotes a throttle means, which is provided between the switching valve 320 and the tank 20 and regulates the flow of pressure oil leaked to the tank 20. The throttle means of the present embodiment is a flow control valve for controlling the flow rate of the pressure oil released to the tank. This makes it possible to stably control the control valve 16 and prevent the operation section from suddenly stopping. Reference numeral 93 denotes a temperature sensor which detects the temperature of oil applied to the hydraulic circuit of the hydraulic device.

Reference numeral 94 denotes a throttle release means, which comprises an electromagnetic valve 95 connected to a hydraulic pressure source 97 and communication means 96 built in a flow control valve 360 as a throttle means, and receives a signal from a temperature sensor 93. When the temperature is equal to or lower than the predetermined temperature, the pressure control valve 360 is operated to bypass the flow control valve 360 to release the pressure oil from the switching valve 320 to the tank 20. For example, when the oil temperature is a predetermined set temperature (in this embodiment, for example, + 10 °
C) In the following cases, the electromagnetic valve 95 is turned on, and the hydraulic oil is supplied from the hydraulic pressure source 97 so as to operate the communication means 96. The pressure oil may be set to escape to the tank 20.

According to the hydraulically operated valve system having the above configuration, when the oil temperature is low, the switching valve 3 is bypassed by the throttle release means 94 by bypassing the throttle means (flow control valve 360).
Communication means 96 so that the pressure oil escapes from
Works, but the viscosity of the hydraulic oil is high due to the low temperature, and the flow of the pressure oil from the switching valve 320 to the tank 20 is slowed down to some extent. In other words, the operation unit is not suddenly stopped, and the flow of the hydraulic oil is too slow to be slow enough to impair the function of the switching valve 320. Therefore, even when the oil temperature is low, it is possible to operate the hydraulic device without causing excessive warm-up operation and suitably operating the hydraulic operation system valve system having the automatic stop function and the shock mitigation function.

(Background Art) Next, a case where the hydraulically operated valve system according to the present invention is applied to a power shovel will be described. Prior to that, the background art will be described in detail with reference to FIGS. I do. FIG. 2 is a sectional view showing a specific example of the valve unit 10 in the operation system valve system of the power shovel according to the background art described with reference to FIGS. 11 and 12. FIG. 3 is a sectional view showing a state where the solenoid is turned off. FIG. 4 is an explanatory diagram illustrating the bypass on-off valve. The valve unit 10 includes first to first
The three switching valves 30, 32, 34, the flow control valves 36, 38, and the bypass on-off valve 45 are provided in an integrated state. 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. Since the boom flow control valve 36 and the arm flow control valve 38 can have the same structure, 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 including a filter is shown in FIG. 2).
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. 52 is an output port, the second control valve 16b (hereinafter, simply referred to as "control valve 16 ', see FIG. 12) is connected to the pressure oil output from the pilot valve 12 (see FIG. 12), the communication passage This port outputs to the control valve 16 via B2. Reference numeral 53 denotes an output connection screw, and an output port 5
It communicates with 2. Numeral 54 denotes a tank port, which is connected to a drain line 19 via a boom flow control valve 36 described later.
From the tank 20. The first switching valve 30
In this case, 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.

Reference 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 disposed such that the drive shaft portion 33 a faces the spring 60 from the right inner end surface 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 projects, as shown in FIG. 2, 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 and a discharge port 68 are 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. Springs 75, 76 on both sides of the spool 70 and the inner wall of the oil chamber 64.
Has a configuration in which it is mounted. The introduction port 66 connects the oil chamber 64 and the tank port 54 of the second switching valve 32 with the communication hole 88b and the flow path 7 during normal operation of the power shovel.
And 8. The discharge port 68 connects the oil chamber 64 and the tank 20 via the drain line 19. The spool 70 has a through hole 71 along the axis.
Is formed, 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 thus constructed shockless valve (boom flow control valve 36) will be described below. First, as shown in FIG. 3, 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.
0, 32, 34, the boom flow control valve 36 and the arm flow control valve 38 are integrated into a valve unit 1
The structure in which 0 is formed will be described. As is apparent from the figure, a first block 81 having the first switching valve 30, a second block 82 having the second switching valve 32 and the boom flow control valve 36, a third switching valve 34, and an arm flow control valve 38.
And a third block 83 having the same.

Also, a bypass on-off valve 45 (see FIG. 11)
Is inserted through each of the blocks 81, 82, 83, and a redundant spool which is inserted through the insertion hole 84 and opens and closes the first to third bypass passages 41, 42, 43 by rotating. 86. The redundant spool 86 includes the first to third bypass passages 41 and 42,
Corresponding to 43, there are provided communication holes 88a, 88b, 88c with openings at both ends of the passage 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. 11) 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 including the above two opening and closing mechanisms, for example, one of the power operated,
The other may be provided to be operated manually to improve reliability. FIG. 4 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 with respect to the second switching valve 32 also here. When the lever 46 of the redundant spool 86 is operated and set as shown in FIG. 2, when the second solenoid 33 is in the ON state, the pressure oil of the pilot valve 12 is clearly shown in FIG.
2, input port 50, inside second switching valve 32 (insertion hole 58
), And is supplied to the control valve 16 through the output port 52 and the communication path B2. This state is referred to as an X communication state. When the boom sensor 26 is operated while the redundant spool 86 remains as described above, that is, when the second solenoid 33 is turned off, the pressure oil supplied to the control valve 16 is transferred to the communication passage B as shown in FIG.
2, output port 52, inside second switching valve 32 (insertion hole 58
Inner), the tank port 54, the communication hole 88b, the flow path 78, the boom flow control valve 36, and the drain line 19 are supplied to the tank 20. 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, the redundant spool 86 of the bypass on-off valve 45 is rotated as shown in FIG. 5 by operating the lever 46, so that the pressure oil of the pilot valve 12 is clearly shown in FIG. A state of supplying 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 (this state , 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 attain the above-mentioned state, the second switching valve 32 is provided in a predetermined structure so that the X-communication state or the Z-communication state is obtained regardless of the position where the spool 56 stops. Needless to say, it is necessary.

Next, as shown in FIGS. 3, 4, 6, 7, and 11, a tank port line 80 provided immediately below the drain line 19 will be described. 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
It is configured such that the discharged oil passes through the tank 20 and returns to the tank 20 (see FIG. 11). On the other hand, the tank port line 80 is disposed close to the drain line 19, and is provided as a passage for the discharged oil discharged from the hydraulic pump and discharged to the tank 20 through a relief valve or the like. . By arranging the tank port line 80 in this manner, the heat of the discharged oil in the tank port line 80 can be transmitted to the discharged oil in the drain line 19. The discharged oil is discharged from the hydraulic pump and is heated. Therefore, at the time of low oil temperature, the temperature of the discharged oil in the drain line 19 can be quickly increased, 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. 12) is provided, for example, between the hydraulic pump 18 and the pilot valve 12 to keep the pressure of the pressure oil supplied to the pilot valve 12 substantially constant. .

According to the system configured as described above, since a computer (precision electronic parts) is not required, 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 addition, in this system, the boom offset is performed at a low speed, and the first switching valve 30 is not provided with the shockless valve. Is the second
Needless to say, a shockless valve may be provided similarly to the switching valve and the third switching valve. In addition, a temperature-guaranteed shockless valve that can be operated even at a low temperature, such as the boom flow control valve 36 and the arm flow control valve 38, is used as the throttle means, but is not limited thereto. , Temperature cannot be guaranteed, but pressurized oil from switching valve
The same effect can be obtained at the point of missing .

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention based on the background art will be described below in detail with reference to FIGS. FIG. 6 is a circuit diagram of the valve unit 100 of the operation system valve system of the power shovel according to the present invention, and shows a state where the working device including the boom and the arm of the power shovel does not operate. FIG.
The same components as those of the background art described based on No. 1 are denoted by the same reference numerals, and description thereof is omitted. This embodiment includes a boom flow control valve 360 in the system described in the background art.
The boom flow control valve 380 is provided with communication means 96, and a temperature sensor 93 and an electromagnetic valve 95 for operating the communication means 96 are provided.

Reference numeral 93 denotes a temperature sensor which detects the temperature of oil applied to the hydraulic circuit of the hydraulic device. The boom throttle release unit includes an electromagnetic valve 95 connected to a hydraulic pressure source 97 and a communication unit 96 built in a boom flow control valve 360 which is a boom throttle unit, and receives a signal from a temperature sensor 93. When the temperature is lower than a predetermined temperature, the boom flow control valve 360 is bypassed and the second switching valve 32 is operated.
Pressure oil can escape to the tank 20. The arm throttle release means includes an electromagnetic valve 95 connected to a hydraulic pressure source 97.
And communication means 96 built in the arm flow control valve 380 which is an arm throttle means.
When the temperature is lower than a predetermined temperature, the pressure oil can be released from the third switching valve 34 to the tank 20 by bypassing the arm flow control valve 380.

For example, when the oil temperature is lower than a predetermined set temperature (in this embodiment, for example, + 10 ° C.), the electromagnetic valve 95 is turned on, and pressure oil is communicated from the oil pressure source 97. The second switching valve 32 and the third switching valve 3 are supplied to actuate the
The pressure oil may be set to escape from the tank 4 to the tank 20. Then, when the oil temperature becomes equal to or higher than a predetermined set temperature, the electromagnetic valve 95 is turned off, the release by the boom throttle release means and the arm throttle release means is released, and the boom flow control valve 360 and What is necessary is just to set so that the arm flow control valve 380 may function.

According to the power shovel using the hydraulically operated valve system having the above structure, when the oil temperature is low, the boom throttle release means and the arm throttle release means use the boom flow control valve 360 and the arm flow rate. Control valve 380
And communication means 96, 9 so that the pressure oil escapes from the second switching valve 32 and the third switching valve 34 to the tank 20.
6, the viscosity of the hydraulic oil is high due to the low temperature, and the flow of the pressure oil from the second switching valve 32 and the third switching valve 34 to the tank 20 is slowed down to some extent. In other words, the boom and the arm are not suddenly stopped, and the flow of the hydraulic oil is too slow and the flow is not slow enough to impair the functions of the second switching valve 32 and the third switching valve 34. Therefore, even when the oil temperature is low, the hydraulic device can be operated without causing excessive warming-up operation and suitably operating the hydraulic operation system valve system having the interference prevention function by the automatic stop function and the shock mitigation function. That is, even at low temperatures, work can be started immediately without impairing the safety functions (interference prevention function and impact mitigation function), and it can be suitably used even in cold regions.

FIGS. 7 to 9 are sectional views showing specific examples of the valve unit 100 in the operation system valve system of the power shovel according to the present invention described with reference to FIGS. 7 and 8 show a state in which the electromagnetic valve 95 is OFF, and FIG. 9 shows a state in which the electromagnetic valve 95 is ON and the communication means 96 communicates. In addition, about the structure same as the background art demonstrated based on FIGS. 2-5, the same code | symbol is attached | subjected except a part and description is abbreviate | omitted. Since the boom flow control valve 360 and the arm flow control valve 380 have the same configuration, only the boom flow control valve 360 will be described here.

The boom flow control valve 360 is connected to the piston 7
7 is built in, but is basically configured in the same manner as the boom flow control valve 26 described in the background art. That is, the introduction port 66 connected to the second switching valve 32 side and the discharge port 68 connected to the tank side are opened in the oil chamber 64. In the oil chamber 64, a spool 70 provided with a fixed throttle 72 communicating the oil chamber 64a on the introduction port side and the oil chamber 64b on the discharge port side is reciprocally inserted. When the spool 70 moves to the oil chamber 64b on the discharge port side, the opening becomes small. Conversely, when the spool 70 moves to the oil chamber 64a on the introduction port side, the opening becomes large and the pressure oil that has passed through the fixed throttle 72 Communication hole 74
Is provided. When the spool 70 largely moves to the oil chamber 64a on the introduction port side, the constriction 96a, which is communication means 96 for communicating the introduction port 66 and the discharge port 68 without passing through the fixed throttle 72, 70 are provided between the communication holes 73 and 74. The constricted portion 96a is provided between the introduction port 66 and the discharge port 6.
8 can be directly communicated so as to be an extremely large communication port as compared with the hole of the fixed throttle 72. Further, a spring 75 on the introduction port side, which is mounted in the oil chamber 63a on the introduction port side in contact with the end on the introduction port side of the spool 70, and a discharge port side of the spool 70 in the oil chamber 64b on the discharge port side. The spring 7 on the discharge port side, which is mounted in contact with the end of the
6 is provided.

The boom flow control valve 360 according to the present embodiment has a built-in piston 77 as one configuration of the throttle release means. The piston 77 is inserted into the oil chamber 64b on the discharge port side so as to reciprocate in the same direction as the moving direction of the spool 70, and receives the spring 76 on the discharge port side. As shown in FIG. 8, reference numeral 95 denotes an electromagnetic valve, which is an example of a driving unit of the piston 77. This solenoid valve 95 is connected to one port 9
5a is connected to the hydraulic pressure source 97 (see FIG. 6), and the other port 95b is connected to the end of the oil chamber 64b on the discharge port side via the communication passage 99. Also, the electromagnetic valve 9
5 is connected so as to be controlled by the temperature sensor 93 (see FIG. 6).

When the electromagnetic valve 95 is turned on, the spool 98 moves, and the one port 95a and the other port 95b communicate with each other through the constricted portion 98a. Pressure oil is introduced into the end of the chamber 64b. As a result, the piston 77 moves, and the movement largely moves the spool 70 to the oil chamber 64a on the introduction port side against the urging force of the spring 75 on the introduction port side (see FIG. 9). The discharge port 68 is directly communicated with the constriction 96a.
That is, the function of the flow control of the boom flow control valve 360 is in a killed state, and it is possible to suitably cope with the case where the oil temperature is low as described above. The electromagnetic valve 95 is similarly connected to the arm flow control valve 380 (see FIG. 6), and the arm flow control valve 380 operates similarly to the boom flow control valve 360. In the present embodiment, the electromagnetic valve 95 is integrated into the valve unit 100. However, the present invention is not limited to this, and it goes without saying that the electromagnetic valve 95 may be provided separately.

[0051] Also in case of mere aperture 90, as shown in FIG. 10 (reference technology), by providing the aperture releasing means 94, the pressure oil from the switching valve to bypass the throttle means
The same effect as in the above-described embodiment can be obtained in terms of escape to the tank . As described above, the present invention has been described variously with reference to preferred embodiments. However, the present invention is not limited to the embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.

[0052]

According to the hydraulically operated valve system according to the present invention, the switching valve is provided between the control valve and the pilot valve, and when the hydraulic device is operated, both are connected to each other, and the signal from the position sensor is transmitted. from the pilot valve upon receipt provided to release the pressure oil being supplied to the control valve while interrupting the supply of pressurized oil to the control valve to the tank, as throttle means
A flow control valve is provided between the switching valve and the tank so as to regulate the flow of the pressurized oil escaping to the tank to be substantially constant, and the flow control valve is prevented from functioning by being bypassed by the throttle release means. can do. Therefore, according to the present invention, can be manufactured at low cost without using a computer as the proportional solenoid valve, the operation unit is automatically stopped when operated outside a predetermined position range, the operation portion is stopped <br The shock at the time of stopping can be reliably and suitably mitigated, and even when the oil temperature is low, the automatic stop function of the operating section can be suitably operated and the hydraulic device can be operated appropriately. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a hydraulically operated valve system according to the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a valve unit according to the background art.

FIG. 3 is a cross-sectional view illustrating an operation state of the background art of FIG. 2;

FIG. 4 is an explanatory diagram illustrating a bypass on-off valve according to the background art.

FIG. 5 is a sectional view showing a use state of the background art in FIG. 2;

FIG. 6 is a circuit diagram showing one embodiment of an operation system valve system of the power shovel according to the present invention.

FIG. 7 is a sectional view showing a specific example of the embodiment of FIG. 6;

FIG. 8 is a sectional view showing a specific example of the aperture release means of the embodiment of FIG. 6;

FIG. 9 is a sectional view showing the operation state of FIG. 7;

FIG. 10 is a sectional view showing a reference technique .

FIG. 11 is a circuit diagram showing one embodiment of an operation system valve system of a power shovel according to the background art.

FIG. 12 is a circuit diagram illustrating a mounting portion of a valve unit.

[Explanation of symbols]

 Reference Signs List 10 valve unit 12 pilot valve 16 control valve 20 tank 24 offset sensor 26 boom position sensor 28 arm position sensor 30 first switching valve 32 second switching valve 34 third switching valve 36 flow control valve for boom 38 flow control valve for arm 41 First bypass passage 42 Second bypass passage 43 Third bypass passage 45 Bypass opening / closing valve 93 Temperature sensor 94 Throttle release means 100 Valve unit 260 Position sensor 320 Switching valve 360 Boom flow control valve 380 Arm flow control valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F15B 21/04 E02F 9/22 F15B 20/00 E02F 9/24

Claims (7)

(57) [Claims] In order to control the operation of a hydraulic device, in a hydraulic operating valve system configured with a control valve and a pilot valve, a signal is output when an operating part of the hydraulic device is operated outside a predetermined set position range. A position sensor to be generated, provided between the control valve and the pilot valve, when operating the hydraulic device, communicating both,
When receiving a signal from the position sensor, a switching valve that shuts off the supply of pressure oil from the pilot valve to the control valve and releases the pressure oil supplied to the control valve to a tank; The flow of pressurized oil that escapes to the tank between the switching valve and the tank
The pressure provided to the tank is provided as a throttle means to regulate
Control the oil flow to be almost constant and at low temperatures
Operable flow control valve and detects the temperature of oil applied in the hydraulic circuit of the hydraulic device
Receiving a signal from the temperature sensor and the temperature sensor, and
The bypass valve and the pressure from the switching valve
A hydraulically actuated valve system comprising: a throttle release means operable to release oil to a tank . 2. The oil flow control valve according to claim 1, wherein an inlet port connected to the switching valve side and a discharge port connected to the tank side are opened in the oil chamber. A spool provided with a fixed throttle that communicates between the chamber and the oil chamber on the discharge port side is reciprocally inserted. When the spool moves to the oil chamber on the discharge port side, the opening becomes smaller and it is introduced in reverse. When moving to the oil chamber on the port side, the opening becomes large and a communication hole for communicating the pressure oil passing through the fixed throttle is provided, and when the spool moves largely to the oil chamber on the introduction port side, A communication means for communicating the introduction port and the discharge port without passing through the fixed throttle is provided, and a spring on the introduction port side elastically mounted in the oil chamber on the introduction port side in contact with an end of the spool on the introduction port side. And the discharge port side A discharge port-side spring elastically mounted in contact with the end of the spool on the discharge port side in the oil chamber, wherein the throttling release means is disposed in the oil chamber on the discharge port side in the same direction as the moving direction of the spool. A piston receiving the spring on the discharge port side, and a pressurized oil being introduced into an end of an oil chamber on the discharge port side to move the piston through the movement of the piston. 2. A hydraulic operation valve system according to claim 1 , further comprising: piston drive means for largely moving the spool to the oil chamber on the introduction port side against the urging force of the spring. 3. A first control valve and a first pilot valve for boom offset, and a second control valve and a second pilot valve for boom rotation for controlling the operation of the boom and arm of the power shovel. A hydraulically actuated valve system having a third control valve and a third pilot valve for pivoting an arm, wherein a signal is output when the boom is offset out of a predetermined range with respect to the base of the excavator. An boom position sensor that generates a signal when the boom pivots up and down and is out of a predetermined range, and an arm that pivots up and down and is out of a predetermined range An arm position sensor for generating a signal when the first control valve and the first pilot valve Provided between them, when offsetting the boom, they communicate with each other, and upon receiving a signal from the offset sensor, shut off the supply of pressure oil from the first pilot valve to the first control valve, A first switching valve for releasing pressurized oil supplied to the first control valve to the tank; and a first switching valve provided between the second control valve and the second pilot valve, which are connected when the boom is rotated. Upon receiving a signal from the boom sensor, the supply of pressure oil from the second pilot valve to the second control valve is interrupted, and the pressure oil supplied to the second control valve is released to the tank. 2 switching valve, provided between the third control valve and the third pilot valve. A third switching valve that shuts off the supply of pressure oil from the third pilot valve to the third control valve and releases the pressure oil supplied to the third control valve to the tank when receiving a signal from the system sensor. When the flow of pressure oil to escape into the tank between the second switching valve and the tank
It is provided as a throttle means to regulate
Control to keep the flow rate of pressurized oil approximately constant and
A flow control valve for a boom that can be operated at any time, and a flow of pressure oil that escapes to the tank between the third switching valve and the tank.
It is provided as a throttle means to regulate
Control to keep the flow rate of pressurized oil approximately constant and
And the arm flow control valve operable in time, a temperature sensor for detecting the temperature of the oil according to the hydraulic circuit of the hydraulic device, in response to a signal from the temperature sensor, when the following Jo Tokoro temperature Bypassing the boom flow control valve ,
Boom that operates to release pressurized oil from the switching valve to the tank
A throttle release means, in response to a signal from the temperature sensor, in the following Jo Tokoro temperature, operating from the bypassing flow control valve for the arm third switching valve so as to release the pressure oil to the tank To do
A power shovel comprising: a diaphragm stop canceling means . 4. The boom flow control valve and the arm.
The flow control valve is connected to the oil chamber on the side of the switching valve.
Port and discharge port connected to the tank side are open
The oil chamber has an inlet port-side oil chamber and a discharge port.
Spool provided with a fixed throttle that communicates with the oil chamber on the side
The spool is inserted reciprocally and the spool is
When moving to the room, the opening becomes smaller,
When moving to the oil chamber on the side of
When a communication hole that communicates pressure oil that has passed through the constant throttle is provided
In both cases, the spool moves greatly to the oil chamber on the introduction port side.
The inlet and outlet ports through the fixed throttle
Communication means for communicating without being provided, the introduction port side
Abutting the end of the spool on the introduction port side in the oil chamber
The spring on the side of the introduction port
Abuts the end on the discharge port side of the spool in the oil chamber on the
And a spring on the discharge port side, which is elastically mounted on the discharge port side.
When inserted reciprocally in the same direction as the
A piston for receiving the spring on the discharge port side
And pressurized oil is introduced into the end of the oil chamber on the discharge port side.
With the movement of the piston,
Place the spool on the introduction port side against the urging force of the pulling
And a piston driving means for moving the piston largely to the oil chamber.
The power shovel according to claim 3, wherein 5. 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. The power shovel according to claim 3, further comprising a bypass on-off valve. 6. A first block having the first switching valve,
A second block having the second switching valve and the boom flow control valve , the third switching valve and the arm flow control
A third block having a valve , wherein the bypass on-off valve has an insertion hole formed to penetrate the first bypass passage, the second bypass passage, and the third bypass passage incorporated in each block; Is inserted through the insertion hole,
The power shovel according to claim 5, further comprising a valve body that simultaneously opens and closes the first bypass passage, the second bypass passage, and the third bypass passage by a moving operation. 7. A drain line provided as a passage for oil discharged from the boom flow control valve and the arm flow control valve to the tank, and disposed in close proximity to the drain line and discharged from a hydraulic pump. 7. The power shovel according to claim 3 , further comprising: a tank port line provided as a passage for discharged oil discharged to a tank through a relief valve or the like.