JPH09317706A - Fall prevention valve device with regenerative function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of relief function of an overload relief valve assembled to a fall prevention valve device and adopt common parts in the fall prevention devices with regenerative function and without regenerative function. SOLUTION: A work port 21 is opened an oil passage 28 between a load holding check valve 24 and a proportional sheet valve 25 serving as a returning side throttling element and a load holding check valve. An oil passage 38 branched from the oil passage 28 is communicated to an inlet of an overload relief valve 26. An outlet port 30 of the proportional sheet valve 25 is interrupted from an outlet port 22 of a valve block 23 by means by means of a wall 23a of the valve block. A regenerating oil passage 50 on which a regenerating check valve 27 is arranged and a regeneration adjusting oil passage 51 are branched from the outlet port 30 of the proportional valve. A returning oil passage 52 is formed so as to be opened to the outlet port of the valve block. A regeneration adjusting device 53 is arranged outside the valve block for controlling communication between the oil passages 51 and 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can prevent a load such as an arm driven by an actuator from dropping if a hose or a steel pipe that transports pressure oil to an actuator in a construction machine such as a hydraulic excavator is damaged. The present invention relates to such a fall prevention valve device, and more particularly to a fall prevention valve device with a regeneration function, which has a regeneration function for returning the return oil discharged from the actuator to the actuator for reuse.

[0002]

2. Description of the Related Art In a construction machine such as a hydraulic excavator, even if a hose or a steel pipe for transporting pressure oil to an actuator is damaged, it is possible to prevent a load such as an arm driven by the actuator from falling. A protective valve device may be attached. As a conventional technology of such a fall prevention valve device, there is one described in Japanese Patent Laid-Open No. 3-249411.

FIG. 7 shows a fall prevention valve device described in Japanese Patent Laid-Open No. 3-249411. In FIG. 7, the fall prevention valve device 100 includes an inlet port 120 connected to the direction switching valve 102, a work port 121 connected to the actuator 103, and an outlet port 122 connected to the tank 109.
A valve block 123 in which each port is formed, a check valve 124 for holding a load, which is arranged between the inlet port 120 and the work port 121 and allows only the flow of pressure oil from the inlet port 120 to the work port 121, and the work port 121. A proportional seat valve 125 arranged between the outlet port 122 and the outlet port 122, and an overload relief valve 126 arranged between the work port 121 and the outlet port 122. It is also configured as a check valve. Further, the overload relief valve 126 is the proportional seat valve 12
Built into 5. In addition, 101 is a hydraulic pump, 1
Reference numeral 40 is a hydraulic pilot device for controlling the opening of the proportional seat valve 125.

If the pipe 104 from the direction switching valve 102 to the inlet port 120 is damaged, the first check valve 124 and the proportional seat valve (check valve) 125 are closed to prevent the load of the actuator 103 from dropping. . At this time, for example, using a jig, the hydraulic pilot device 120
By operating the spool 141 and adjusting the opening degree of the proportional seat valve 125, the load can be slowly moved to a safe position by its own weight.

On the other hand, in a recently developed hydraulic excavator, the use of a regenerating circuit is increasing for the purpose of energy saving and speedup of an actuator, for example, Japanese Patent Laid-Open No. 63-83.
An example is described in Japanese Patent No. 808. This regeneration circuit is generally configured to recirculate and return the return oil discharged from the rod side of the hydraulic cylinder to the bottom side of the hydraulic cylinder via the regeneration check valve for reuse (regeneration). Further, in the regeneration circuit disclosed in Japanese Patent Laid-Open No. 63-83808, a regeneration adjusting valve is arranged in the pipe connecting the rod side of the hydraulic cylinder to the tank, and the rod side of the hydraulic cylinder and the tank are operated by operating this regeneration adjusting valve. Is controlled to adjust the amount of regeneration returned to the bottom side of the hydraulic cylinder.

[0006]

All of the above-mentioned prior arts are for cases where the fall prevention valve device or the regeneration circuit is used alone. However, when adding a function as a regeneration circuit to the fall prevention valve device, it is necessary to connect the outlet port of the valve block of the fall prevention valve device (the outlet port of the proportional seat valve) to the regeneration circuit. However, in the conventional fall prevention valve device 100 shown in FIG. 7, since the overload relief valve 126 is incorporated in the proportional seat valve 125, the outlet port of the proportional seat valve 125 (the outlet port 12 of the valve block 12
When the regeneration circuit is connected to 2), the relief oil from the overload relief valve 126 passes through the regeneration adjustment valve of the regeneration circuit, which increases the pressure loss and may impair the relief function.

In the hydraulic excavator, the fall prevention valve device is mounted on the bottom side pipe and rod side pipe of the arm cylinder, the bottom side pipe of the boom cylinder, and the like.
In the hydraulic excavator, the mounting portion of the regeneration circuit is usually limited to the rod side pipe of the arm cylinder. Therefore, the outlet port 122 of the proportional seat valve 125 of the fall prevention valve device 100.
If a regenerative circuit is installed to connect to, the fall prevention valve device will be a dedicated fall prevention valve device with a regeneration function, and there will be two types of fall prevention valves: a normal fall prevention valve device without a regeneration function and a fall prevention valve device with a regeneration function. A device is required, and the cost is high.

An object of the present invention is to provide a drop prevention valve device having a regeneration function and a fall prevention valve device having a regeneration function without impairing the relief function of an overload relief valve incorporated in the fall prevention valve device. It is an object of the present invention to provide a fall prevention valve device with a regeneration function that can be shared.

[0009]

In order to solve the above-mentioned problems, the present invention forms an inlet port connected to a directional control valve, a work port connected to an actuator, and an outlet port connected to a tank. And a first check valve for holding a load, which is arranged between the inlet port and the work port and allows only the flow of pressure oil from the inlet port to the work port, and is arranged between the work port and the outlet port. Fall prevention valve device including a proportional seat valve and an overload relief valve arranged between the work port and the outlet port, and using the proportional seat valve also as a return side throttle element and a second check valve for holding load In, the work port is opened in a first passage between the first check valve and the proportional seat valve, and the work port is separated from the first passage. The second passage communicates with the inlet of the overload relief valve, the outlet port of the proportional seat valve is blocked from the outlet port of the valve block by the wall of the valve block, and the outlet of the proportional seat valve is connected. Regeneration check valve where regeneration check valve is placed from port
While branching the passage and the fourth passage for regeneration adjustment,
A fifth return passage is formed so as to open to the outlet port of the valve block, and a regeneration adjusting device for controlling communication between the fourth passage and the fifth passage is attached to the outside of the valve block.

In the present invention thus constructed, when the load pressure of the actuator becomes extremely high, the high pressure oil is passed through the work port, the first passage and the second passage and is supplied by the overload relief valve. It escapes to the tank via the outlet port of the valve block. Further, during normal operation of the actuator, the pressure oil discharged from the actuator is opened through the work port, the first passage, and the proportional seat valve to the outlet port of the proportional seat valve to the third regeneration port.
If the regeneration adjusting device blocks the communication between the fourth passage and the fifth passage by being guided to the passage and the fourth passage for regeneration adjustment,
If the entire amount of pressure oil that has passed through the proportional seat valve is returned to the actuator via the regeneration third passage and the regeneration check valve, and the regeneration adjusting device does not block the communication between the fourth passage and the fifth passage, , Part of the pressure oil that has passed through the proportional seat valve is discharged to the tank through the fourth passage, the regeneration adjusting device, the fifth passage, and the outlet port of the valve block, and the rest is the regeneration flow rate and the third passage for regeneration. It is returned to the actuator via the regeneration check valve, and the regeneration flow rate at this time is the flow rate adjusted by the regeneration adjusting device.

Further, if the pipe from the direction switching valve to the inlet port of the valve block is damaged, the first check valve and the proportional seat valve (second check valve) are closed to prevent the actuator load from dropping. To do. At this time, the load can be slowly moved to a safe position by the weight of the load by adjusting the opening of the proportional seat valve.

While adding the regeneration function to the fall prevention function as described above, the relief oil from the overload relief valve is discharged to the tank from the outlet port of the valve block without passing through the regeneration adjusting device. Function is secured.

Further, as described above, in the structure in which the third passage for regeneration, the fourth passage for regeneration adjustment, and the fifth passage for return are formed in the valve block, and the check valve for regeneration and the regeneration adjusting device are provided. Although it is a fall prevention valve device with a regeneration function, in the configuration in which the third passage, the fourth passage, and the fifth passage are not formed and the regeneration check valve and the regeneration adjusting device are not arranged, the outlet port of the proportional seat valve and the valve block By making a hole in the wall of the valve block that shuts off the outlet port, the outlet port of the proportional seat valve communicates with the outlet port of the valve block, providing a fall prevention valve device without a regeneration function. As a result, parts can be shared between the fall prevention valve device having no regeneration function and the fall prevention valve device having a regeneration function.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIGS.
This will be described with reference to FIG.

First, a hydraulic circuit in which the fall prevention valve device with a regeneration function of the present invention is used will be described with reference to FIG.

In FIG. 1, reference numeral 1 is a hydraulic pressure source including a hydraulic pump, and pressure oil from the hydraulic pressure source 1 is sent to an actuator 3 via a direction switching valve 2. The actuator 3 is an arm cylinder having a rod side 3a and a bottom side 3b, and when the directional control valve 2 is moved to a position I on the left side in the drawing by the hydraulic signal Sa, the rod side of the arm cylinder 3 is connected via the pipes 4 and 5. When pressure oil is sent to 3a, the arm cylinder 3 moves in the direction of contraction of the rod, that is, in the direction of 6a, and when the directional control valve 2 moves to the position of III on the right side in the figure by the hydraulic signal Sb, it passes through pipes 7 and 8. Pressure oil is sent to the bottom side 3b of the arm cylinder 3, and the arm cylinder 3 moves in the extending direction of the rod, that is, in the direction of 6b. When the direction switching valve 2 moves to the position II in the center of the drawing, the supply of pressure oil to the arm cylinder 3 is cut off and the arm cylinder 3 stops. In addition,
9 is a tank.

The hydraulic circuit as described above is provided with the fall prevention valve device 10 with a regeneration function and the fall prevention valve device 11 without a regeneration function according to this embodiment.

FIG. 2 shows the front structure of the hydraulic excavator to which the arm cylinder 3 is attached, and the installation location of the fall prevention valve device and the regeneration circuit.

In FIG. 2, reference numeral 12 is a front of the hydraulic excavator, and the front 12 is composed of a boom 12a vertically moved by a boom cylinder 13, an arm 12b vertically moved by the arm cylinder 3, and an attachment cylinder 15. It is composed of a front attachment that is moved back and forth, and in the illustrated example, a crusher 12c. In such a hydraulic excavator, as a part to which the fall prevention valve device is attached, the part A of the pipe on the rod side 3a of the arm cylinder 3 and the part of the arm 12b for the arm are operated in the range of a). )
The bottom side 3b of the arm cylinder 3 for the operation in the range
There is a part B of the piping of the above, and there is a part C of the bottom side piping of the boom cylinder 13 for the boom.

Further, as a mounting portion of the reproducing circuit, there is a portion A of the rod side pipe of the arm cylinder 3 with respect to the movement of the arm 12b in the range of a).

In this embodiment, the rod-side pipes 4 and 5 of the arm cylinder 3 are provided with a fall prevention valve device 10 having a regeneration function, and the bottom pipes 7 and 8 of the arm cylinder 3 are provided with a fall prevention valve device 11 having no regeneration function. Is provided. This allows
In the operating range of the arm 12b b), the directional control valve 2
Even if the pipe 4 between the arm cylinder 3 and the rod side 3a of the arm cylinder 3 is damaged, the arm 12b and the crusher 12c are prevented from falling, and the return oil discharged from the rod side 3a of the arm cylinder 3 is removed. By returning to the bottom side 3b and returning it, energy can be saved and the speed of the arm cylinder 3 can be increased (action of the fall prevention valve 10). Further, even if the pipe 7 between the direction switching valve 2 and the bottom side 3b of the arm cylinder 3 is damaged in the operation range of the arm 12b), the fall of the arm 12b and the crusher 12c is prevented. (Operation of the fall prevention valve 11).

In FIG. 1, the fall prevention valve devices 10, 1 are shown.
Although the pipes 5 and 8 are provided between the arm cylinder 1 and the arm cylinder 3, the fall prevention valve devices 10 and 11 are actually provided.
Is directly attached to the arm cylinder 3,
There is no pipe 5, 8 such as a pipe or hose.

Next, the structure of the fall prevention valve device 10 with a regeneration function will be described.

The fall prevention valve device 10 with a regeneration function comprises an inlet port 20 connected to the direction switching valve 2 via a pipe 4,
A work block 21 connected to the rod side 3a of the arm cylinder 3 and a valve block 23 in which each port of an outlet port 22 connected to the tank 9 via a pipe 16 is formed. A check valve 24, a proportional seat valve 25 that also serves as a return side throttle element and a load holding check valve, an overload relief valve 26, and a check valve 27 for regeneration are incorporated.

The load holding check valve 24 is connected to the inlet port 2
0 is arranged between the work port 21 and the work port 21, and is of a seat valve type that allows only the flow of pressure oil from the inlet port 20 to the work port 21. The flow is completely cut off.

Further, the check valve 24 and the proportional seat valve 25
An oil passage 28 is formed between them, and the work port 21 opens into the oil passage 28. That is, the proportional seat valve 25 is arranged at a position sandwiching the work port 21 with respect to the check valve 24, and the oil passage 28 connecting the check valve 24 and the work port 21 extends to the inlet port 29 of the proportional seat valve 24.

The overload relief valve 26 is arranged between the work port 21 and the outlet port 26, and an oil passage 38 branched from the oil passage 28 extends and communicates with the inlet portion of the overload relief valve 26. The overload relief valve 26 is a relief valve that is very commonly used in the past.
Illustration and description of the internal structure are omitted.

The proportional seat valve 25 is a seat valve body 31 for controlling opening / closing and communication of the inlet port 29 and the outlet port 30.
A back pressure chamber 32 provided on the opposite side of the outlet port 30 of the seat valve body 31, an oil passage 33 and a slit 34 connecting the inlet port 29 provided on the seat valve body 31 with the back pressure chamber 32. And the slit 34 allows the valve block 23
A variable aperture 35 is formed between the and.

A pilot valve device 40 is attached to the outside of the valve block 23 by bolting or the like, and the position of the seat valve body 31 of the proportional seat valve 25 is controlled by the pilot valve device 40. The details of the pilot valve device 40 are the same as those of the conventional device shown in FIG. 7, and therefore, in FIG.

The pilot valve device 40 has a spool 41, a pressure receiving portion 42, and a spring 43, and the pressure receiving portion 42 has a signal pressure Sb for switching the directional control valve 2 to the III position as shown by an asterisk * in FIG. Is branched and transmitted, and urges the spool 41 in the valve opening direction. At this time, the position of the spool 41 is determined by the balance between the magnitude of the hydraulic signal Sb and the force of the spring 43.
The inlet side of the spool 41 is connected to the back pressure chamber 32 of the proportional seat valve 25 via an oil passage 44, and the outlet side is connected to the oil passage 45.
Connected to the outlet port 30 via.

When there is no signal pressure Sb and the directional control valve 2 is in the neutral position II, the spool 4 of the pilot valve device 40
1 is in the shut-off position, and the seat valve body 3 of the proportional seat valve 25
1 is also in the blocking position.

When the directional control valve 2 is switched to the position III by the signal pressure Sb, the spool 41 of the pilot valve device 40 is
Moves in the valve opening direction from the shutoff position, and the inlet port 29 → oil passage 33 → slit 34 → variable throttle 35 → oil passage 44 →
A pilot flow rate according to the opening degree (opening area) of the spool 41 flows from the spool 41 → the oil passage 45 → the outlet port 30, and a differential pressure is generated before and after the variable throttle 35 due to the pilot flow rate. An upward force, that is, a force in the valve opening direction is generated in the seat valve body 31. Spool 41
The pilot flow rate increases as the valve opening of
As a result, the seat valve element 31 of the proportional seat valve 25 moves upward, the opening degree of the variable throttle 35 is increased, and the position of the seat valve element 31 of the proportional seat valve 25 is controlled according to the valve opening degree of the spool 41. To do. When the proportional seat valve 25 opens, the pressure oil on the rod side 3a of the arm cylinder 3 flows out to the outlet port 30 via the work port 21, the oil passage 28, and the inlet port 29.

In this way, the rod side 3 of the arm cylinder 3
The flow rate flowing out from a is the seat valve body 3 of the proportional seat valve 25.
It is controlled depending on the position of 1, that is, the signal pressure Sb. Further, since the proportional seat valve 25 is a seat valve, it functions as a check valve when the seat valve body 31 is in the shutoff position,
The flow of pressure oil from the work port 21 toward the outlet port 30 is completely shut off.

The outlet port 30 of the proportional seat valve 25 is shut off from the outlet port 22 of the valve block 23 by the wall portion 23a of the valve block 23, and the outlet port 30 and the outlet port 2 are separated from each other.
2 is not directly connected.

On the other hand, the outlet port 30 of the proportional seat valve 25
From this, a regeneration oil passage 50 and a regeneration adjustment oil passage 51 are branched, and the regeneration check valve 27 is arranged in the regeneration oil passage 50. Further, the return oil passage 52 is formed so as to open to the outlet port 22 of the valve block 23,
A regeneration adjusting device 53 that controls communication between the oil passage 51 and the oil passage 52 is attached to the outside of the valve block 23.

From the above, as described above, the outlet port 30
When the pressure of the pressure oil flowing out to the arm cylinder 3 becomes higher than the pressure on the bottom side of the arm cylinder 3, the pressure oil flows back to the fall prevention valve device 11 through the oil passage 50 and the regeneration check valve 27 as shown by an arrow 54. Further, it is supplied to the bottom side 3b of the arm cylinder 3 via the pipe 8. Here, the oil passage 50,
If there is no 51 and regeneration adjusting device 53, the total amount of pressure oil that has flowed out of the proportional seat valve 25 is 3 at the bottom side of the arm cylinder 3.
However, in the case of a hydraulic excavator that requires both fine operability and high speed, it is not always preferable to reproduce the entire amount. Therefore, it is desirable to add a function of adjusting the regeneration flow rate, and a regeneration adjusting device 53 is provided for that purpose.

That is, a part of the pressure oil flowing out to the outlet port 30 according to the adjustment degree of the regeneration adjusting device 53 is part of the oil passage 51,
It is returned from the regeneration adjusting device 53, the oil passage 52, and the outlet port 22 to the tank 9 via the pipe 16, and the rest is returned to the bottom side 3b of the arm cylinder 3 as a regeneration flow rate. Also,
The regeneration flow rate is adjusted by changing the amount returned to the tank 9 by the regeneration adjusting device 53.

The structure of the reproduction adjusting device 53 is as follows.

The regeneration adjusting device 53 has a valve block 60 bolted to the valve block 23 and a spool 61 that slides in the valve block 60. The valve block 60 has an inlet connected to the oil passages 51 and 52. A port 62 and an outlet port 63 are formed, and the spool 61 has a flow control notch 6
4 is formed, and when the spool 61 moves downward with respect to the valve block 60 by the flow control notch 64, a variable throttle 65 for reproduction adjustment whose opening is small is formed.
A piston 66 is located on the upper end side of the spool 61 in the figure, and a hydraulic chamber 68 closed by a plug 67 is formed in the spool 61. A signal pressure Sx is introduced into the hydraulic chamber 68 through a small hole 70 provided in the plug 67. Get burned. On the other hand, a spring 69 is arranged on the lower end side of the spool 61 in the figure. Spool 61
Position, that is, the opening of the variable throttle 65 is determined by the balance between the signal pressure Sx that is guided to the hydraulic chamber 68 and acts on the piston 66 and the spring 69.

As the signal pressure Sx, for example, the above signal pressure Sb can be used. In this case, the signal pressure Sb
In the small operation area where is small, the flow control notch 64 (variable throttle 6
It is possible to increase the flow rate returned to the tank side via 5) to decrease the regeneration flow rate and decrease the flow rate returned to the tank side as the signal pressure Sb increases to increase the regeneration flow rate.

Next, a fall prevention valve device 11 having no regeneration function
Will be described with reference to FIG. In FIG. 3, the same parts and portions as those of the fall prevention valve device 10 with a regeneration function shown in FIG.

As can be seen from the comparison between FIG. 3 and FIG. 1, since the fall prevention valve device 11 does not require a regeneration function, the oil passages 51 and 52 and the regeneration adjustment device 53 are not provided, and the proportional seat valve is not provided. An opening 80 is formed in the wall portion between the outlet port 30b of 25b and the outlet port 22b of the valve block 23, and the outlet port 30b is directly connected to the outlet port 22b through the opening 80.

Further, the pressure receiving portion 4 of the pilot valve device 40b
2b is the direction switching valve 2 as shown by the white star
The signal pressure Sa for switching to the position is branched and transmitted, and when the direction switching valve 2 is switched to the I position, the pilot valve device 4
The spool 41b of 0b moves in the valve opening direction from the shutoff position, and the pressure oil on the bottom side 3b of the arm cylinder 3 flows out from the outlet ports 30b and 22b to the tank 9 through the work port 21b, the oil passage 28b, and the inlet port 29b. . At this time, the flow rate is set to the seat valve body 3 of the proportional seat valve 25b.
It is controlled according to the position of 1b, that is, the signal pressure Sa.

The other structure of the fall prevention valve device 11 is the same as that of the fall prevention valve device 10.

The hydraulic circuit including the above-mentioned fall prevention valve devices 10 and 11 is shown by hydraulic symbols as shown in FIG.

Next, the operation of the fall prevention valve devices 10 and 11 configured as described above will be described.

First, when the directional control valve 2 is moved to the position I on the left side in the figure by the hydraulic signal Sa, pressure oil is sent from the hydraulic pressure source 1 to the rod side 3a of the arm cylinder 3 via the pipes 4 and 5, and the arm is moved. Cylinder 3 is the contraction side of the rod, that is, 6
Although it moves in the direction of a, at this time, in the fall prevention valve device 10, the check valve 24 opens to allow the flow of pressure oil from the inlet port 20 to the work port 21. Further, when the pressure oil is guided to the rod side 3a of the arm cylinder 3 in this way, the overload relief valve 26 and the proportional seat valve 2
No pressure oil leaks from 5.

On the other hand, when the arm cylinder 3 moves as described above, the proportional seat valve 25b of the fall prevention valve device 11 is used.
Is opened by the signal pressure Sa, and the arm cylinder 3
The pressure oil discharged from the bottom side 3b is returned to the tank 9 through the pipe 8, the fall prevention valve device 11, and the pipe 16b.
At this time, the flow rate is controlled according to the position of the seat valve body 31b of the proportional seat valve 25b, that is, the signal pressure Sa.

The same applies when the direction switching valve 2 is moved to the position III on the right side in the figure by the hydraulic signal Sb and pressure oil is sent to the bottom side 3b of the arm cylinder 3 via the pipes 7 and 8. The pressure oil guided to the bottom side 3b of the valve 3 is the overload relief valve 26b of the fall prevention valve device 11.
And there is no leakage from the proportional seat valve 25b,
The flow rate of the pressure oil discharged from the rod side 3a of the arm cylinder 3 is controlled according to the position of the seat valve body 31 of the proportional seat valve 25 of the fall prevention valve device 10, that is, the signal pressure Sb.

At this time, when the arm 12b is in the range of 2) in FIG. 2, the load pressure on the bottom side 3b of the arm cylinder 3 becomes low, so that the pressure at the outlet port 30 of the proportional seat valve 25 becomes. Higher than the load pressure,
A part of the pressure oil flowing out to the outlet port 30 of the proportional seat valve 25 is returned from the oil passage 51, the regeneration adjusting device 53, the oil passage 52, and the outlet port 22 to the tank 9 through the pipe 16, but the rest is the regeneration flow rate. Is returned to the bottom side 3b of the arm cylinder 3. At this time, as described above, the signal pressure Sx
As the signal pressure Sb is used as
As b increases, the flow rate returned to the tank side can be reduced, the regeneration flow rate can be increased, and energy can be saved and the speed of the arm cylinder 3 can be increased.

Then, when the directional control valve is returned to the neutral position of II, the check valve 24 or 24b, the proportional seat valve 25
25b, there is no leak from the overload relief valve 26 or 26b, so when the arm 12b is at the stop position in the range of (a) of FIG. 2, the rod of the arm cylinder 3 does not move in the extension direction, When the arm 12b is at the stop position in the range of (b) of FIG. 2, the rod of the arm cylinder 3 does not move in the contraction direction, and the load can be held respectively.

On the other hand, when a large external force acts on the arm cylinder 3 in the rod extending direction with the directional control valve 2 in the neutral position II, there is no escape for the pressure oil, so the rod side 3a of the arm cylinder 3 is in an emergency state. It will cause a very high pressure and may damage the equipment. As an example, FIG. 2 shows an example in which a heavy-duty crusher 12c is attached to the front 12, but a normal bucket is attached to the front and the rope is broken using the pawls of the bucket, and this rope is attached to the boom 12a. It is possible to pull it by raising it.

In such a case, in this embodiment, the overload relief valve 26 incorporated in the fall prevention valve device 11 is used.
And the high pressure oil on the rod side 3a of the arm cylinder 3 passes through the work port 21, the oil passages 28, 38, the overload relief valve 26, and the outlet port 22 to the tank 9
I will run away to. Further, at this time, the overload relief valve 26 is separated from the proportional seat valve 25, and the downstream side of the overload relief valve 26 is the direct outlet port 22.
Since it is connected to, the relief function is not impaired.

Next, if pressure oil is sent to the rod side 3a of the arm cylinder 3 and the arm cylinder 3 is moved to the contracted side of the rod, should the pipe 4 be damaged, the fall prevention valve device 10 Since the check valve 24 is closed, the pressure oil on the rod side 3a of the arm cylinder 3 does not flow out anywhere, and the movement of the arm cylinder 3 is stopped. When the stop position is in the range of (a) in FIG. 2, it is necessary to allow the pressure oil on the rod side 3a of the arm cylinder 3 to escape to move the front 12 to a safe position. In such a case, in the present embodiment,
By operating the spool 41 of the pilot valve device 40 of the fall prevention valve device 10 by the signal pressure Sb and opening the proportional seat valve 25, the rod side 3a of the arm cylinder 3
Can be discharged to the tank, and by adjusting the signal pressure Sb at this time, the flow rate discharged from the rod side 3a of the arm cylinder 3 to the tank can be adjusted. Thereby, the front 12 can be slowly moved to a safe position.

Incidentally, instead of using the signal pressure Sb, an appropriate jig is used to make the spool 41 of the pilot valve device 40.
May be operated to release the pressure oil on the rod side 3a of the arm cylinder 3 using the own weight of the front 12 to move the front 12 to a safe position.

In the event that the pipe 7 is damaged and the arm cylinder 3 is stopped while pressure oil is being sent to the bottom side 3b of the arm cylinder 3 and the arm cylinder 3 is being moved to the extension side of the rod. Even when the stop position is within the range of (b) in FIG. 2, the front 12 can be slowly and safely moved to a safe position by performing the same operation on the fall prevention valve device 11 as described above. You can

Therefore, according to this embodiment, the following effects can be obtained.

(1) During normal operation of the actuator, that is, during operation of the arm cylinder 3 in the direction of contraction of the rod (dump operation of the arm 12b) and in operation of the extension of the rod (cloud operation of the arm 12b), overload relief The pressure oil does not leak from the valve 26 and the proportional seat valve 25. Further, the load can be held when the directional control valve is neutral.

(2) Even if the pipe 4 or the pipe 7 is damaged, the pressure oil of the arm cylinder 3 does not flow out anywhere, the arm 12b can be prevented from falling, and the weight of the front 12 can be used. The pressure oil in the arm cylinder 3 can be gradually released to move the front 12 slowly to a safe position.

(3) When the arm 12b is in the range of (a) in FIG. 2 due to the operation of the rod of the arm cylinder 3 in the extending direction, the signal pressure Sb of the pressure oil discharged from the rod side 3a of the arm cylinder 3 is increased. The corresponding portion is returned to the bottom side 3b of the arm cylinder 3 as the regeneration flow rate, so that energy saving and speed increase of the arm cylinder 3 can be achieved.

(4) When the directional control valve 2 is in the neutral position and a large external force acts on the arm cylinder 3 in the rod extension direction, the relief oil from the overload relief valve 26 does not pass through the regeneration adjusting device 53 and the valve block. It is discharged from the outlet port 22 of 23 to the tank 9. Therefore, while adding the playback function to the fall prevention function as in (3) above,
The overload relief function is secured. Further, since the function of the overload relief valve 26 is separated from the proportional seat valve 25, there are no restrictions on the dimensions of the spring and the spring receiving sleeve that form the relief valve, and it is easy to cope with recent high pressure. Further, the work port 21 is arranged between the check valve 24 and the proportional seat valve 25, and the space is used to arrange the overload relief valve 26 between the check valve 24 and the proportional seat valve 25 which are the same as the work port 21. It is possible to cope with the high pressure of the overload relief function without impairing the overall size.

(5) A common directional control valve can be used regardless of the presence or absence of a fall prevention valve device, and moreover, a regeneration function can be fulfilled in addition to the fall prevention function.

Since the function of the overload relief valve 26 is separated from the proportional seat valve 25, the proportional seat valve 2
5, the restriction of the relief function of the overload relief valve 26 is eliminated, and even if the outlet port 30 of the proportional seat valve 25 is connected to the inlet port 20 of the valve block 23, the return oil from the actuator 3 in the normal operation is switched in direction. It can be returned to the tank via valve 2. In this case, if the directional control valve 2 with the regenerating function is used, the regenerating function can be achieved without adding the regenerating function to the fall prevention valve device 10. But,
The fall prevention valve device may or may not be required depending on the specifications of the hydraulic excavator. In order to enable the flow rate control function of the return oil from the actuator 3 to be exhibited even when the fall prevention valve device is not required. Generally, the direction switching valve 2 also has a return oil flow rate control function. In this case, if the fall prevention function of the fall prevention valve device does not require a flow rate control function, the proportional seat valves 25, 25b are simply seat valves that operate on-off, and the return oil flow rate control function is a directional switching valve. You can do it in 2.

By the way, as described above, the fall prevention valve devices 10 and 11 according to the present invention allow the return oil from the actuator 3 to move the front to a safe position in the event that the pipe 4 or 7 is damaged. Is not an on-off type and is required to be able to be controlled arbitrarily. Therefore, it is essential that the fall prevention valve devices 10 and 11 use the proportional seat valves 25 and 25b and have a flow rate control function. When the flow rate control function is provided by the proportional seat valves 25 and 25b as described above, if the return oil from the proportional seat valves 25 and 25b is returned to the tank through the direction switching valve 2, the flow rate control function of the return oil is performed. However, the flow control function is impaired because the drop prevention valve device and the function of the directional control valve overlap, and the directional control valve 2 must be changed to an on-off type without a return side throttle element. That is,
If the basic circuit is one without a fall prevention valve device, the directional control valve of this basic circuit should have a return side throttle element on the spool, and if the fall prevention valve device is installed, the spool of the directional control valve should be connected to the return side throttle element. It must be replaced with an on-off type that has no elements.

As described above, in the present invention, the outlet port of the proportional seat valve 25 is connected to the valve block 23 in order to avoid replacing the spool of the directional control valve even when the fall prevention valve device is mounted.
Is connected not to the inlet port 20 but to the outlet port 30 and is returned to the tank without passing through the direction switching valve 2. However, in this case, even if the directional control valve 2 has a regeneration function, the regeneration function cannot be used. Therefore, the fall prevention valve device 10 is equipped with a regeneration adjusting device 53, and the fall prevention valve device itself has a regeneration mechanism. As a result, the common directional control valve can be used regardless of the presence or absence of the fall prevention valve device, and moreover, the regeneration function can be achieved in addition to the fall prevention function.

(6) In addition, the drop prevention valve device 1 with a regeneration function is provided at the portion A of the pipe on the rod side 3a of the arm cylinder 3.
0 is mounted, and the fall prevention valve device 11 having no regenerating function is mounted at the portion B of the pipe on the bottom side 3b of the arm cylinder 3, but the fall prevention valve device 10 having a regenerating function and the fall prevention valve device having no regenerating function are mounted. 11 and the main configuration is the same,
Both devices can share parts.

That is, in the fall prevention valve device 11 shown in FIG. 3, the opening 8 is formed in the wall portion 23a for blocking the outlet port 30 of the proportional seat valve 25 and the outlet port 22 of the valve block 23.
Prepare a common part that does not open 0, form oil passages 50-51 in the valve block of this part, equip the oil passage 50 with a check valve 27 for regeneration, and adjust the regeneration outside the valve block. If the device 53 is bolted, the fall prevention valve device 10 with a regeneration function is obtained, and the proportional seat valve 25
If the opening 80 is opened in the wall 23a that blocks the outlet port 30 of the valve block 23 and the outlet port 22 of the valve block 23 with a drill or the like, the fall prevention valve device 11 having no regeneration function can be obtained. By thus sharing the parts, it is possible to add a reproducing function to the fall prevention valve device and reduce the cost.

Another embodiment of the present invention will be described with reference to FIGS. In the figure, members or functions equivalent to those shown in FIGS. 1 and 4 are designated by the same reference numerals.

In the above-described embodiment, the signal pressure Sb of the directional control valve 2 is used as the signal pressure Sx of the regeneration adjusting device 53, but in the present embodiment, other signals are used as the signal pressure Sx.

In FIG. 5, a regeneration adjusting device 53A provided in the fall prevention valve device 10A with a regeneration function of this embodiment.
Is a valve block 6 bolted to the valve block 23A.
0A and a spool 61A that slides in the valve block 60A
The valve block 60A has an inlet port 62 and an outlet port 63 connected to the oil passages 51 and 52, and an oil passage 90 connected to the back pressure chamber of the check valve 27 for regeneration, and the spool 61A has an opening / closing notch. 64A and throttle passage 9
1 is formed, the opening / closing notch 64A is closed by the valve block 60A when the spool 61A is in the position shown in the drawing, the inlet port 62 and the outlet port 63 communicate with each other through the throttle passage 91, and the spool 61A moves downward in the drawing. Then, the opening / closing notch 64A is opened, and the inlet port 62 and the outlet port 63 communicate with the throttle passage 91 via the opening / closing notch 64A. Further, a piston 66A is located on the upper end side of the spool 61A in the figure, and a hydraulic chamber 68 closed by a plug 67A.
A is formed, and the oil passage 90 is formed in the hydraulic chamber 68A.
The load pressure of the back pressure chamber of the check valve 27 for regeneration, that is, the bottom side 3b of the arm cylinder 3 is introduced as a signal pressure Sx via the. On the other hand, a spring 69A is arranged on the lower end side of the spool 61A in the figure, and biases the opening / closing notch 64A of the spool 61A in the closing direction.

The hydraulic circuit including the above-mentioned fall prevention valve device 10A is shown by hydraulic symbols as shown in FIG.

In this embodiment, when the arm cylinder 3 is moved in the rod extending direction by the hydraulic signal Sb,
When the arm 12b is in the range (a) in FIG. 2, the spool 61A is shown in a normal operating state in which the load pressure (signal pressure Sx) on the bottom side 3b of the arm cylinder 3 is higher than the pressure set by the spring 69A. Is moved downward from the position, the inlet port 62 and the outlet port 63 communicate with the throttle passage 91 through the opening / closing notch 64A, and most of the return oil from the rod side 3a of the arm cylinder 3 is the oil passage 52 and the outlet port. It is discharged to the tank 9 via 22. On the other hand, when the load pressure on the bottom side 3b of the arm cylinder 3 becomes lower than the set pressure of the spring 69A, the spool 61A moves to the position shown in the figure, and the inlet port 62 and the outlet port 63 communicate with each other only via the throttle passage 91. Therefore, a part of the return oil from the rod side 3a of the arm cylinder 3 is supplied to the bottom side 3b of the arm cylinder 3 as a regeneration flow rate, and the regeneration flow rate at this time is a flow rate determined according to the degree of throttling of the throttle passage 91. Becomes

As described above, various reproduction functions can be exerted by using the signals given to the reproduction adjusting device.

[0074]

According to the present invention, the following effects can be obtained.

(1) Since the fall prevention valve device is provided with a regeneration function and the overload relief function is secured, and the overload relief valve is arranged by utilizing the work port arrangement space, It is possible to cope with the high pressure of the overload relief function without impairing the overall size.

(2) Since a fall prevention valve device without a regeneration function can be constructed by making minor changes to the main components of the fall prevention valve device with a regeneration function, parts can be shared by both devices and the cost can be reduced. Is possible.

(3) Since the fall prevention valve device itself has a regeneration mechanism to return the return oil directly to the tank from the outlet port of the valve block, a common directional control valve is provided regardless of the presence or absence of the fall prevention valve device. Can be used, and in addition to the fall prevention function, the playback function can be reliably achieved.

(4) Various reproduction functions can be exhibited depending on how to use the signal given to the reproduction adjusting device.

[Brief description of drawings]

FIG. 1 is a diagram showing a fall prevention valve device with a regeneration function according to a first embodiment of the present invention together with a hydraulic circuit.

FIG. 2 is a diagram showing a portion where a fall prevention valve device is used.

FIG. 3 is a diagram showing a fall prevention valve device having no regeneration function.

FIG. 4 is a circuit diagram showing hydraulic circuits including hydraulic pressure symbols including the fall prevention valve device shown in FIG.

FIG. 5 is a diagram showing a main part of a fall prevention valve device with a regeneration function according to a second embodiment of the present invention.

6 is a circuit diagram showing hydraulic circuits including hydraulic pressure symbols including the fall prevention valve device shown in FIG.

FIG. 7 is a diagram showing a conventional fall prevention valve device.

[Explanation of symbols]

 1 Hydraulic power source 2 Directional switching valve 3 Actuator (arm cylinder) 3a Rod side 3b Bottom side 4,7 Piping 9 Tank 10 Fall prevention valve device with regeneration function 11 Fall prevention valve device without regeneration function 12 Front 12a Boom 12b Arm 12c Front Attachment 20 Inlet port 21 Work port 22 Outlet port 23 Valve block 24 Load holding check valve 25 Proportional seat valve 26 Overload relief valve 27 Regeneration check valve 28 Oil passage 29 Oil inlet port 29 Proportional seat valve inlet port 30 Proportional seat valve outlet port 40 Pilot valve device 50 Regeneration oil passage 51 Regeneration adjustment oil passage 52 Return oil passage 53 Regeneration adjustment device

Claims (1)

[Claims] 1. A valve block in which an inlet port connected to a directional control valve, a work port connected to an actuator, and an outlet port connected to a tank are formed.
A first check valve for retaining the load, which is arranged between the inlet port and the work port and allows only the flow of pressure oil from the inlet port to the work port, and a proportional seat valve arranged between the work port and the outlet port, A fall prevention valve device, comprising: an overload relief valve arranged between the work port and the outlet port, wherein the proportional seat valve also serves as a return side throttle element and a second check valve for holding a load. A second passage opened to the first passage between the first check valve and the proportional seat valve and branched from the first passage communicates with the inlet of the overload relief valve. The outlet port of the valve block is shut off from the outlet port of the valve block by the wall portion of the valve block, and the regeneration port The third passage for regeneration in which the check valve is arranged and the fourth passage for regeneration adjustment are branched, and a fifth passage for return is formed so as to open to the outlet port of the valve block, A fall prevention valve device with a regeneration function, wherein a regeneration adjusting device for controlling communication between the fourth passage and the fifth passage is attached to the outside of the.