JPH01169104A - Rapid drop prevention device for work machine cylinder - Google Patents

Abstract

PURPOSE:To increase the maximum descent speed of a work machine cylinder by providing a drop prevention valve between an operation valve and a lifting chamber of the work machine cylinder, with the drop prevention valve gradually increasing its opening area by means of a descent signal of the operation valve. CONSTITUTION:A line 11 is provided with a drop prevention valve 16 provided with a pilot spool valve 22, a check valve 21 and a main poppet valve 20 passing through a 1st oil hole 18 and a 2nd oil hole 19. The main poppet valve 20 and the pilot spool valve 22 constitute a flow rate control section. It is arranged such that at the time of descent position of an operation valve 12, the opening of the operation valve 12, namely the opening areas of a 1st port 121 and a drain port 124, and the opening of the poppet valve 20, namely the opening areas of the 1st oil hole 18 and the 2nd oil hole 19 increase according to the magnitude of the descent signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a work machine that is vertically operated by a work machine cylinder, such as arm-type work of a power shovel, and a conduit connecting the work machine cylinder and a control valve. This device relates to a device that prevents a device from falling rapidly when it breaks.

[Conventional technology]

As shown in FIG. 3, a fall prevention valve 4 is disposed in a conduit 3 that connects the operation valve 1 and the lifting chamber 2a of the working machine cylinder 2, and a flow rate control section 5 of the fall prevention valve 4 is Raising room 2
The pipeline that connects the anti-fall valve 4 and the operating valve 1 by holding it in the first position 51, which prevents the flow from a to the operating valve 1 side and allows the flow towards the raising chamber 2a, is damaged. In addition to preventing oil in the raising chamber 2a from flowing out even if the operating valve 1
A lowering signal for switching the lowering position I to the lowering position I is sent to the flow rate control section 5 to control the flow rate to match the opening degree of the operation valve 1,
By allowing the oil in the lifting chamber 2a to flow to the drain through the operation valve 1, the work machine cylinder 2 can be lowered, and even if the pipe line is damaged during the lowering operation, the work machine cylinder 2 is prevented from falling rapidly. A device that has been used for this purpose is known.

[Problem that the invention seeks to solve]

With this device, the opening degree of the operating valve 1 and the opening degree (flow rate) of the flow rate control section 5 are synchronized to control the flow rate flowing from the raising chamber 2a to the drain side, so that the opening degree of the operating valve during the lowering operation is controlled. In order to ensure flow controllability and control the work machine cylinder speed after a pipe breakage, it is necessary to set the opening degree of the flow rate control unit 5 to be larger than the opening degree of the operation valve 1 by α, as shown in FIG. 4. .

This causes the following problems.

(1) In order to be able to synchronize even if the opening areas of the operating valves vary, it is necessary to adjust the opening area of the flow rate controller.

(2) When lowering the work machine cylinder 2, the raising chamber 2a
Since the oil inside is throttled by the flow rate control section 5 and the operating valve 1, pressure loss becomes large and the maximum lowering speed of the working machine cylinder becomes slow.

(3) If the pipe line 3 is damaged at the X mark position during the lowering operation of the work equipment cylinder, the oil in the raising chamber 2a will flow only through the flow rate control section 5, so the lowering speed will be reduced by the amount that does not flow through the operation valve 1. As the speed increases, the work equipment may collide with obstacles, such as objects on the ground or people.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rapid fall prevention valve for a working machine cylinder that can solve the above problems.

[Means and effects for solving the problem] A fall prevention valve is provided between the lifting chamber of the work equipment cylinder and the operating valve, and the opening area of the lifting chamber and the operating valve is gradually increased by a lowering signal of the operating valve. The downstream side of the drop prevention valve is connected to the tank side via a check valve that opens and operates in response to the lowering signal, so that the downstream side of the drop prevention valve is at about the tank pressure during normal lowering operation. be.

〔Example〕

As shown in FIG. 1, the lifting chamber 10 of the working machine cylinder 10
a is connected to the first port 121 of the operating valve 12 through the pipe 11, the lowering chamber 10b is connected to the second port 122 through the pipe 13, and the inlet boat 123 of the operating valve 12 is connected to the hydraulic pump 14. , the drain boat 124 is connected to the tank 15 and held at a neutral position N that cuts off each boat, and when a lowering signal is input, the inlet port 123 is connected to the second port 122.
The inlet boat 123 is connected to the first boat 121 and the second port 122 is connected to the drain boat 124. Switch to position U.

The up signal and down signal are pilot pressure, current, etc., and are pilot pressure in the embodiment.

The pipe line 11 is provided with a fall prevention valve 16, which has a first oil hole 18 and a second oil hole 19 bored in the valve body 17, and the first oil hole 18 and the second oil hole. 19, a main poppet valve 20, a check valve 21, and a pilot spool valve 22 are provided. 10, and the second oil hole 19 communicates with the pipe line 11.

The main poppet valve 19 has a poppet valve 2 in the sleeve 23.
4, and the spool 25 is inserted into the poppet valve 24, and the poppet valve 24 is connected to the sleeve 2 by the spring 26.
3, the first oil hole 18 and the second oil hole 19 are blocked off, and the first oil hole 18 communicates with the inside of the poppet valve 24 via the boat 27 and the slit groove 28.
The inside communicates with a chamber 31 through a boat 29 and a boat 30, and the poppet valve 24 receives a force in the closing direction from the spring 26 and the hydraulic pressure of the first oil hole 18 acting on the chamber 24a inside the poppet valve. The hydraulic pressure of the second oil hole 19 acting on the front surface of the poppet valve 24 and the first oil hole 18 acting on the shoulder of the poppet valve 24
It is designed to receive force in the opening direction using hydraulic pressure.

The check valve 21 has a valve body 32 held by a seat 34 with a spring 33.
The first oil hole 18 is seated in the first oil hole 18 to block the flow from the first oil hole 18 to the second oil hole 19, while allowing the flow from the second oil hole 19 to the first oil hole 18.

The pilot spool valve 22 has a spool 36 inserted into a sleeve 35, and the inlet boat 3 communicates with the chamber 31.
7 is connected to a chamber 39 opened to the second oil hole 19 by a drill hole 38, and the spool 36 is held in a position where the inlet boat 37 and the chamber 39 are isolated by a spring 40, and communicated by a piston 41. The lowering signal is input to the pressure receiving chamber 41a of the piston 41.

The second oil hole 19 is connected to the tank 1 by a pilot type check valve 42.
5, and when a lowering signal is input to the pilot type check valve 42, the second oil hole 19 is communicated with the tank 15.

Next, the operation will be explained.

1. When the operation valve is in the neutral position, no lowering signal is input to the pressure receiving chamber 41a of the piston 41, the spool 36 is in the cutoff position, and the inlet port 37 and the chamber 3 are closed.
9 is shut off, the chamber 31 becomes a dead end, and the oil in the lifting chamber 10a of the working machine cylinder 10 cannot flow out, so the working machine cylinder 10 does not move downward.

2. When the operating valve is in the raised position, the pressure oil discharged from the hydraulic pump 14 is delivered to the first port 121, pipe 1
1, the oil in the lowering chamber 10b is supplied to the raising chamber 10a through the second oil hole 19, the check valve 21, and the first oil hole 18, and the oil in the lowering chamber 10b is
3. Since the water flows from the second boat 122 and the train boat 124 to the tank 15, the working machine cylinder 10 moves upward.

3. When the operation valve is in the lowered position, the pressure oil discharged from the hydraulic pump 14 is transferred to the second boat 122 and the pipe line 1.
3 to the lowering chamber 10b, and a lowering signal is input to the pressure receiving chamber 41a of the piston 41 to lower the spool 3.
b toward the communication position, and the chamber 31 communicates with the second oil hole 19.

As a result, the holes in the lowering chamber 10a are connected to the first oil hole 18, the boat 27, the slit groove 28, the boat 29 of the chamber 24 inside the poppet valve, the boat 30, the chamber 31, the inlet port 37, and the chamber 3.
9. Flows through the drilled hole 38 to the second oil hole 19, and flows through the first oil hole 1
8 and the chamber 31, the pressure in the chamber 31 becomes lower than the pressure in the first oil hole 18, and as the poppet 24 moves against the spring 26, it separates from the seat 23a and the first The oil hole 18 and the second oil hole 19 communicate with each other and the oil in the lowering chamber 10a flows into the tank 15, so that the working machine cylinder 10 is lowered.

At this time, the opening degree of the operation valve 12, that is, the opening area of the first boat] 21 and the drain boat 124, and the opening degree of the main poppet valve 20, that is, the opening area of the first oil hole 18 and the second oil hole 19, are As shown in the figure, it increases gradually depending on the magnitude of the falling signal.

On the other hand, the pilot type check valve 42 is fully opened by the lowering signal, and the second oil hole 19 is communicated with the tank 15, so the second oil hole 19 is opened before the main poppet valve 20 of the fall prevention valve 16 opens.
In other words, the downstream side of the fall prevention valve 16 opens largely into the tank 15, and the downstream pressure becomes approximately the tank pressure.

That is, the opening area of the pilot type check valve 42 is made sufficiently large so that the downstream pressure of the main poppet valve 20 (the pressure of the second oil hole 19) becomes approximately the tank pressure even when the maximum flow rate is passed.

Therefore, the lowering speed of the work machine cylinder 10 can be controlled by gradually increasing the opening degree of the main poppet valve 20 in proportion to the lowering signal as shown in FIG.

46 When the pipe line breaks at the operating valve lowering position When the pipe line 11 breaks at the x mark position (a), the pressure at that position (a) becomes atmospheric pressure, but this position (a) is normally at approximately Since the tank pressure is the tank pressure (atmospheric pressure at the midline of the tank), the descending speed can be controlled by the drop prevention valve 6 in the same way as during normal lowering operation.

〔Effect of the invention〕

During the lowering operation, the downstream side of the fall prevention valve 16 is at about the tank pressure, and the fall prevention valve 16 is closed regardless of the opening degree of the operation valve 12.
Since the descending speed can be controlled by the control valve 12, there is no need to adjust the opening degree of the drop prevention valve 16 even if the opening degree of the operating valve 12 varies, and the pressure loss when flowing through the operating valve 12 is extremely small. Not only can the maximum lowering speed of the work equipment cylinder 10 be increased, but even if the pipe line 11 between the fall prevention valve 16 and the operating valve 12 is broken, the downstream side of the fall prevention valve 16 can be operated in the same manner as during normal lowering operation. Therefore, there is no sudden change in the descending speed of the working machine cylinder, and the descending speed can be controlled by the fall prevention valve 16.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a chart showing the opening degrees of the operating valve and fall prevention valve, Fig. 3 is an explanatory diagram of the conventional example, and Fig. 4 is the operating valve and fall prevention valve. It is a chart showing the opening degree of a valve. 10 is a working machine cylinder, 10a is a lifting chamber, 11 is a pipe line,
12 is an operation valve, 16 is a fall prevention valve, and 42 is a pilot 2 reverse valve. Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] The lifting chamber 10a of the work machine cylinder 10 is connected to the fall prevention valve 16.
The fall prevention valve 16 is connected to the raising chamber 10 by a lowering signal of the operating valve 12.
A, and the opening area of the pipe line 11 is gradually increased, and the downstream side of the fall prevention valve 16 is connected to the tank side through a check valve that opens and operates in response to the lowering signal. Rapid fall prevention device.