JPH078141Y2 - Hydraulic impact tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic impact tool used, for example, for rock cutting, building destruction, pavement cracking, and the like. The present invention relates to a hydraulic impact tool capable of preventing fluctuations in operating pressure (hereinafter referred to as IN pressure) due to fluctuations.

[Prior Art] Generally, as shown in FIG. 2, a hydraulic impact tool includes a piston member 2 inserted in a hydraulic impact tool body 1 so as to be movable back and forth, and a tool body 1 in the hydraulic impact tool body 1. A switching valve 5 for supplying / discharging hydraulic oil to / from the front chamber 3 and the rear chamber 4 formed by the piston member 2 to switch the moving direction of the piston member 2 and the hydraulic oil in the rear chamber 4 and the front chamber 3. Oil passage 6a
~ 6g, and the hydraulic oil in the front chamber 3 and the rear chamber 4
An accumulator 8 that communicates with the pressure oil supply passage 7 is provided in order to supply the oil quickly and stably. The inside of this accumulator 8 is divided into two chambers by a bladder 8a,
One chamber 8b is filled with an inert gas such as nitrogen, and the other chamber
8c is communicated with the pressure oil supply passage 7 through a large number of small diameter holes.

Generally, in a hydraulic impact tool equipped with an accumulator 8, the IN pressure of hydraulic oil becomes unstable during non-steady state such as startup, and the accumulator 8 is excessively used.
When the pressure is low, the bladder 8a is struck by the pressure of the inert gas on the wall portion between the accumulator 8 and the pressure oil supply passage 7 in which a small diameter hole is formed, and in an extreme case, there is a problem in that it is damaged.

Therefore, a pressure receiving portion 9b, which is slidably attached to the oil passages 6e and 6f of the drainage passage and receives the hydraulic pressure of the hydraulic fluid (this is referred to as IN pressure), is formed at the rear end of the pressure receiving portion. It has already been proposed to have a valve member 9 that is moved backward by the hydraulic pressure acting on 9b to increase the amount of discharged oil, and a preset pressure setting means 10A that moves the valve member 9 forward to decrease the amount of discharged oil. (See Japanese Utility Model Publication No. 62-19180).

The preset pressure setting means 10A is a preset pressure setting spring 1
0a and an adjusting screw 10x for adjusting the preset pressure by adjusting the position of the rear end thereof are provided.

In this conventional hydraulic impact tool, if the IN pressure decreases, the preset pressure setting spring 1 of the preset pressure setting means 10A
The valve member 9 is moved forward by 0a, the cross-sectional area of the oil passage communicating from the oil passage 6e to the oil passage 6g is reduced by the valve member 9, and the hydraulic pressure in the rear chamber 4 is prevented from decreasing more than a certain degree. The oil pressure of the oil supply passage 7, that is, the IN pressure is prevented from falling below a certain level. As a result, the frequency with which the bladder 8a of the accumulator 8 is struck on the wall portion where the small diameter hole is formed between the accumulator 8 and the pressure oil supply passage 7 is reduced, and the impact is weakened, and the durability of the bladder 8a is reduced. Is increased.

[Problems to be Solved by the Invention] However, according to the above-described conventional hydraulic impact tool, the preset pressure adjusting screw 10x is fixed after the preset pressure is adjusted during manufacturing, and the valve member 9 is fixed to the pressure receiving surface 9b. Since the position is determined by the balance between the hydraulic pressure of the acting IN pressure and the spring force of the spring 10x, for example, a hydraulic impact tool is transferred from one construction machine to another construction machine, and a hydraulic pump of a new construction machine is used. When the capacity or discharge amount of the oil is larger than that of the previous construction machine, the valve member 9 holds the same position unless the IN pressure fluctuates. Therefore, the oil passages 6a and 6f and 6g
Since the area of the throttle passage between the
The hydraulic pressure of 6e rises more than that of the previous construction machine, and the IN pressure also rises accordingly. As a result, the spring 10a is compressed, the valve member 9 is displaced, the cross-sectional area of the throttle passage is expanded, and the hydraulic pressure of the oil passage 6e is reduced, but it is not reduced to the hydraulic pressure of the oil passage 6e at the time of the previous construction machine. There is a problem that the IN pressure becomes higher and the striking force becomes stronger than necessary.

In order to solve this problem, the preset pressure adjustment screw 10x should be readjusted according to the pump capacity of the hydraulic power source, but in reality it is difficult for the user to perform such adjustment work. is there.

An object of the present invention is to provide a hydraulic impact tool capable of preventing fluctuation of IN pressure with respect to fluctuation of supply amount of hydraulic oil.

[Means for Solving the Problems]

A hydraulic striking tool according to the present invention supplies a hydraulic fluid to a piston member which is inserted into a hydraulic striking tool body so as to be movable back and forth and a front chamber or a rear chamber formed by the hydraulic striking tool body and the piston member. A switching valve for discharging and switching the moving direction of the piston member, an oil discharge passage for discharging the operating oil in the front chamber or the rear chamber, and a slidable mount on the oil discharge passage, and the operation end at the rear end. The pressure receiving part that receives the oil pressure of oil is formed,
In the hydraulic impact tool having a valve member that retreats by the hydraulic pressure acting on the pressure receiving portion to increase the amount of drained oil, and a preset pressure setting means that advances the valve member to reduce the amount of drained oil, the preset pressure setting Means for presetting the preset pressure setting spring for urging the valve member forward, a plunger provided so as to be movable back and forth for receiving a rear end of the preset pressure setting spring, and a preset pressure adjusting partitioning the front end by the plunger. A pressure receiving chamber, a first oil passage for supplying the working oil to the pressure receiving chamber to increase the preset pressure, and a pressure adjusting valve interposed in the first oil passage for setting the hydraulic pressure of the working oil to a predetermined set pressure. And a second oil passage for supplying the working oil to the pressure receiving chamber to make the preset pressure higher than the set pressure of the pressure adjusting valve, and the oil pressure of the drain oil passage interposed in the second oil passage is a predetermined drain oil pressure. Second when lower than A first shut-off valve to open the road,
The third oil passage for discharging the hydraulic oil supplied to the pressure receiving chamber to lower the preset pressure, and the third oil passage interposed in the third oil passage when the oil pressure in the drain oil passage is higher than a predetermined exhaust oil pressure. A second shut-off valve that opens the oil passage, and a third shut-off valve that is interposed in a portion of the first oil passage downstream of the pressure adjusting valve and shuts off the first oil passage when the internal pressure of the pressure receiving chamber is lower than a predetermined value. It is equipped with a valve.

[Operation] In the hydraulic impact tool of the present invention, when the discharge amount of the hydraulic pump (not shown) connecting the hydraulic impact tool changes to increase, the exhaust hydraulic pressure of the oil discharge passage becomes higher than the specified value, The second cutoff valve interposed in the third oil passage is opened. As a result, a part of the pressure oil in the pressure receiving chamber is discharged to the oil discharge passage through the third oil passage, the internal pressure of the pressure receiving chamber becomes low, and the third cutoff valve in the first oil passage is shut off. The preset pressure is reduced, the valve member moves to the side of increasing the amount of drained oil, and the drain oil pressure is reduced to a specified value. In this way, the exhaust oil pressure is reduced to the specified value, so that the oil pressure of the hydraulic oil does not rise above the predetermined pressure.

Further, when the discharge amount of the hydraulic pump fluctuates toward the smaller side, the exhaust hydraulic pressure becomes lower than the specified value, the first cutoff valve interposed in the second oil passage is opened, and the preset pressure adjustment The preset pressure in the pressure receiving chamber 10c becomes higher than the set pressure of the compression regulating valve, the preset pressure is increased, and the valve member moves to the drain oil amount reduction side, so that the drain oil pressure is raised to the specified value. Thus, the exhaust pressure is increased to the specified value, and the IN pressure does not drop below the predetermined pressure.

[Effect of the Invention] According to the hydraulic impact tool of the present invention, as described above,
The preset pressure is decreased or increased in response to an increase or decrease in the flow rate of hydraulic oil supplied to the hydraulic impact tool,
The valve member enlarges or reduces the flow passage cross-sectional area of the drainage throttle passage to correct the exhaust oil pressure to a specified value, thereby preventing fluctuations in the IN pressure with respect to fluctuations in the flow rate of hydraulic oil supplied to the hydraulic impact tool. be able to.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a main part of a configuration of a hydraulic hammering device for civil engineering work according to an embodiment of the present invention. The same components as those of the conventional device shown in FIG. 2 have the same reference numerals. There is.

This hydraulic impact tool is, for example, a backhoe, not shown.
It is configured to be supported at the tip of an arm of a construction machine such as Yumpo, receive pressure oil from a hydraulic pump of the construction machine, and return waste oil to a hydraulic oil tank of the construction machine.

This hydraulic striking device includes a piston member 2 inserted into a hydraulic striking tool body 1 so as to be movable back and forth, and a front chamber 3 and a rear chamber formed between the hydraulic striking tool body 1 and the piston member 2. 4, a switching valve 5 for supplying and discharging hydraulic oil to switch the moving direction of the piston member 2, an oil discharge passage 6 for discharging hydraulic oil from the front chamber 3 and the rear chamber 4, the front chamber 3 and the rear chamber 4 And a hydraulic oil supply passage 7 for supplying hydraulic oil from a hydraulic pressure supply source, an accumulator 8, and a hydraulic pressure of the hydraulic oil in the pressure oil supply passage 7 (hereinafter, referred to as
(Referred to as IN pressure) and the hydraulic oil pressure P of the hydraulic oil discharged from the rear chamber 4.
_a (a hydraulic pressure of the oil passages 6d and 6e in FIG. 1) and a valve member 9 that adjusts the flow rate of pressure oil from the oil passages 6d and 6e to the oil passage 6f. And a preset pressure setting mechanism 10 for setting the exhaust oil pressure P _a via.

The hydraulic impact tool body 1 has a cylinder chamber 1a for accommodating the piston member 2 therein.
A front chamber 3 is formed on the outer peripheral side of the first piston member 2a of the piston member 2 of 1a, and a rear chamber 4 is formed on the outer peripheral side of the second piston portion 2b.

A pilot valve hole 3c that is opened and closed by the first piston portion 2a is provided in the middle portion of the front chamber 3, and a portion 3a in front of the pilot valve hole 3c of the front chamber 3 is always communicated with the pressure oil supply passage 7. There is.
A portion 3b of the front chamber 3 which is behind the pilot valve hole 3c is communicated with the pilot pressure receiving chamber 5c of the switching valve 5 by an oil passage 5j, and when the piston member 2 is retracted from a predetermined position, the front portion is formed by the first piston portion 2a. When the piston member 2 is retracted further than this, it is communicated with an oil passage 6a forming a part of the oil discharge passage 6.

Explaining the switching valve 5, the first piston portion 2a, the pilot valve hole 3c, and the front chamber 3 (3a, 3b) form a part of the switching valve 5, but the switching valve 5 is a cylinder of the tool body 1. Sleeve valve member slidably mounted in the hole
5b and a fixed member 20 in which the first half portion is slidably fitted in the sleeve valve member 5b and the latter half portion is fitted in the tool main body 1. The sleeve valve member 5b includes a supply port 7a and an oil passage chamber 5a.
The space is opened and closed, and the space between the oil passage chamber 5a and the oil passage 6d is opened and closed.

A first pressure receiving surface 5d that receives the pressure of the pressure oil supply port 7a is formed at the front end of the sleeve valve member 5b, a pilot pressure receiving chamber 5d is formed at the rear end, and a pilot pressure receiving chamber 5c is formed at the rear end. Is formed with a second pressure receiving surface 5e that receives the internal pressure of. Further, an oil passage chamber 5a connected to the supply port 7a and the rear chamber 4 by an oil passage 4a is provided in front of the first pressure receiving surface 5d at the outer peripheral portion of the front end portion thereof.
A valve surface 5f that opens and closes the space is formed, and the valve surface 5g at the inner periphery of the sleeve valve member 5b near the front end and the valve body portion 20 at the front end of the fixed member 20 are formed.
The oil passage chamber 5a and the oil passage 6d are opened and closed by a and the oil passage chamber 5a and the oil passage 6d are opened when the sleeve valve member 5b is moved rearward to open between the supply port 7a and the oil passage chamber 5a. The space is closed, and the valve body 5b
Moves forward and when the supply port 7a and the oil passage chamber 5a are closed, the oil passage chamber 5a and the oil passage 6d communicate with each other through the throttle passage 6c on the outer peripheral side of the valve body portion 20a.

Explaining the oil discharge passage 6 described above, the port 3d for removing pressure oil in the front chamber 3 is connected to the collective oil discharge passage 6g by the oil passage 6a, and the rear chamber 4 is connected to the oil passage chamber 5a by the oil passage 4a. , The oil passage chamber 5a is a throttle passage
It is intermittently connected to the oil passage 6d inside the fixing member 20 via 6c. The oil passage 6d is composed of an oil passage that penetrates the fixing member 20 in an orthogonal manner and an oil passage formed in the central portion of the fixing member 20,
On the downstream side of the oil passage 6d, an oil passage 6e having a larger diameter than this and an oil passage 6f having a larger diameter than this oil passage 6e and connected to the collecting oil discharge passage 6g are formed in order, and the first half portion of the valve member 9 is It extends rearward across the collective oil discharge passage 6g and is inserted into the oil passage 6f to be fitted in the oil passage 6e so as to be slidable in an oil-tight manner.

Explaining the valve member 9, the front half of the valve member 9 is formed in a tubular shape, and the front end of the valve member 9a receives the hydraulic pressure of the oil passage 6e.
Is formed, and the latter half is housed in a cylinder hole formed in the fixed member 20, and the piston portion at the rear end of the valve member 9 is formed.
An annular oil chamber 21 is formed on the front side of 9f, the annular oil chamber 21 is connected to the pressure oil supply passage 7 by an oil passage 7a, and a pressure receiving portion 9b for receiving IN pressure is formed at the front end portion of the piston portion 9f. ing. An oil passage 9c that connects the oil passages 6d and 6e is formed at the front end of the valve member 9, and the oil passage 9c and the collecting oil discharge passage 6g are connected to the oil passage 9c on the peripheral wall of the oil passage 9c.
Small-diameter communication holes 9d communicating with each other via 6f are formed so as to be regularly arranged in the circumferential direction and the axial direction.

The latter half portion of the valve member 9 has a larger diameter than the front half portion, and a spring accommodating portion 9g that opens to the rear end is formed in the latter half portion, and the spring accommodating portion 9g is communicated with the oil passage 9c through the communication hole 9e. There is. Exhaust Thus, since the acting discharge pressure P _a is also the rear end surface of the valve member 9, the valve member 9 which acts on the rear end surface of the exhaust pressure P _a and the valve member 9 which acts on the front end face of the valve member 9 Hydraulic pressure P _a and pressure receiving part 9 b
IN pressure that acts on acts. The area difference between the front end face and the rear end face of the valve member 9 is relatively small, and the exhaust oil pressure P _a is IN
Since it is smaller than the pressure, the oil pressure acting on the valve member 9 is dominated by the oil pressure of the IN pressure acting on the pressure receiving surface 9b.

Therefore, the valve member 9 basically acts on the pressure receiving portion 9b IN
The position is determined by the balance between the hydraulic pressure of the pressure and the elastic force of the preset pressure setting spring 10a of the preset pressure setting mechanism 10, and when the IN pressure rises, the valve member 9 moves backward and the communication hole 9d.
Expanding the area of the throttle passage consisting, thereby discharging the hydraulic pressure P _a
When the IN pressure decreases, the valve member 9 moves forward to reduce the area of the throttle passage to increase the IN pressure.

Here, the following preset pressure setting mechanism 10 is employed so that the IN pressure does not rise even when the flow rate of the pressure oil supplied from the pressure oil supply passage 7 increases.

That is, the preset pressure setting mechanism 10 includes a preset pressure setting spring 10a for urging the valve member 9 forward, and a plunger 10b mounted in a cylinder hole of the tool body 1 for receiving the rear end of the preset pressure setting spring 10a. Preset pressure adjusting pressure receiving chamber whose front end is divided by this plunger
10c and the 1st oil passage 11, the 2nd oil passage 13, and the 3rd oil passage 15 which were connected to this pressure receiving room 10c are provided.

The first oil passage 11 connects the pressure receiving chamber 10c to a portion of the pressure oil supply passage 7 upstream of the switching valve 5, and when the internal pressure of the pressure receiving chamber 10c is higher than a predetermined value, the first oil passage 11 is connected. The third shut-off valve 17 installed in the valve 11 is opened, and the third cutoff valve 17 of the first oil passage 11 is opened.
The hydraulic oil adjusted to the set pressure by the pressure adjusting valve 12 provided upstream of the shutoff valve 17 is supplied to the pressure receiving chamber 10c to set the preset pressure of the pressure receiving chamber 10c.

The second oil passage 13 is connected in parallel with the first oil passage 11 between the pressure receiving chamber 10c and a portion of the pressure oil supply passage 7 upstream of the switching valve 5, so that the oil pressure in the oil passage chamber 5a is predetermined. When the pressure is lower than the pressure, the first cutoff valve 14 interposed in the second oil passage 13 is opened to supply the working oil to the pressure receiving chamber 10c, and the preset pressure is higher than the set pressure of the pressure adjusting valve 12. It is designed to be used.

The third oil passage 15 is connected between the pressure receiving chamber 10c and the collecting oil discharge passage 6g, and is inserted in the third oil passage 15 when the oil pressure in the oil passage chamber 5a is higher than a predetermined value. The 2 cutoff valve 16 is opened, and the hydraulic oil supplied to the pressure receiving chamber 10c is discharged to the collecting oil discharge passage 6g to lower the preset pressure.

A check valve 19 is provided downstream of the third cutoff valve 17 in the first oil passage 11 to prevent the hydraulic oil from flowing back toward the first oil passage 11 when the first cutoff valve 14 is opened. It is equipped.

In the hydraulic striking device configured as described above, the sleeve valve member 5b moves rearward, supplies the working oil to the rear chamber 4 through the oil passage chamber 5a and the oil passage 5b, and moves the piston member 2 forward. Due to this, the oil pressure in the pilot pressure receiving chamber 5c rises and the sleeve valve member 5b again moves forward, closing the supply port 7a and the oil passage chamber 5a and communicating between the oil passage chamber 5a and the oil passage 6d, and this is repeated. The piston member 2 is driven back and forth.

By the way, when the hydraulic pressure and the amount of oil supplied from the construction machine are specified values, the third cutoff valve 17 of the first oil passage 11 is opened and the pressure is adjusted in the pressure receiving chamber 10c by the pressure adjusting valve 12. The hydraulic oil is supplied and operates in the same manner as a conventional hydraulic impact tool.

Then, for example, as in the case of replacing the hydraulic impact device with a construction machine having a hydraulic pump whose discharge amount is larger than the specified value, the flow rate of the hydraulic oil supplied to the pressure oil supply passage 7 is larger than the specified value. If made, the oil pressure in the oil passage chamber 5a becomes higher than the predetermined value in accordance with the increase in the exhaust pressure P _a, the second shut-off valve 16 of the third oil passage 15 is opened. As a result, a part of the pressure oil in the pressure receiving chamber 10c is discharged to the collecting oil discharge passage 6g through the third oil passage 15 to lower the hydraulic pressure in the pressure receiving chamber 10c, while the third shutoff valve 17 is closed. . In this way, the plunger 10b retracts according to the reduction of the preset pressure, and the valve member 9 moves rearward until the oil pressure of the IN pressure acting on the pressure receiving portion 9b and the spring force of the spring 10a are balanced, and the oil passage 6e. set oil discharge passage 6g been throttle passage area is enlarged to connect the the discharge pressure P _a decreased to, oil pressure in the oil passage chamber 5a fluctuations in lowered with iN pressure to a predetermined value is prevented.

On the other hand, for example, the flow rate of the hydraulic oil supplied to the pressure oil supply passage 7 is regulated as in the case where the hydraulic striking device is replaced with a construction machine having a hydraulic pump whose discharge amount is smaller than a prescribed value. When it becomes smaller than the value, the oil pressure in the oil passage chamber 5a becomes lower than the predetermined value in accordance with the decrease in the exhaust oil pressure P _a , and the second
The first cutoff valve 14 interposed in the oil passage 13 is opened, the hydraulic pressure in the pressure receiving chamber 10c becomes higher than the set pressure of the pressure adjusting valve 12,
The preset pressure rises, the valve member 9 moves forward, the area of the throttle passage is reduced, the discharge hydraulic pressure P _a rises, the hydraulic pressure of the oil passage chamber 5a is raised to a predetermined value, and the fluctuation of the IN pressure is prevented. To be done.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of a configuration of a hydraulic striking device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing a main part of a configuration of a hydraulic striking device according to a conventional example. 1 ... Hydraulic impact tool body, 2 ... Piston member, 3 ...
Front chamber, 4 ... Rear chamber, 5 ... Switching valve, 6a-6g ... Oil passage, 9 ... Valve member, 9b ... Pressure receiving part, 10 ... Preset pressure setting means, 10a ... Preset pressure setting spring , 10b ...... Plunger, 10c ...... Pressure receiving chamber, 11 ...... First oil passage, 12 ...... Pressure adjusting valve, 13 ...... Second oil passage, 14 ...... First shut-off valve, 15 ...... Third oil passage , 16 …… Second shutoff valve, 17 …… Third shutoff valve.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A piston member, which is inserted into a main body of a hydraulic impact tool so as to be movable back and forth, and a piston which supplies and discharges hydraulic oil to a front chamber or a rear chamber formed by the main body of the hydraulic impact tool and the piston member. A switching valve for switching the moving direction of the member, an oil discharge passage for discharging the hydraulic oil in the front chamber or the rear chamber, and a slidable mount on the oil discharge passage, and a hydraulic pressure of the hydraulic oil for the rear end portion. A pressure receiving portion for receiving is formed, and has a valve member that retreats by the hydraulic pressure acting on the pressure receiving portion to increase the amount of discharged oil, and a preset pressure setting means that advances the valve member to reduce the amount of discharged oil. In the hydraulic impact tool, the preset pressure setting means includes a preset pressure setting spring that biases the valve member forward, a plunger that is movable forward and backward to receive a rear end of the preset pressure setting spring, and the plunger. Yo A preset pressure adjusting pressure receiving chamber whose front end is partitioned, a first oil passage for supplying the working oil to the pressure receiving chamber to increase the preset pressure, and a hydraulic pressure of the working oil interposed in the first oil passage. A pressure adjusting valve for setting a predetermined set pressure, a second oil passage for supplying the working oil to the pressure receiving chamber to make the preset pressure higher than the set pressure of the pressure adjusting valve, and a second oil passage interposed in the second oil passage. A first shutoff valve that opens the second oil passage when the oil pressure in the oil discharge passage is lower than a predetermined oil pressure, and a third oil passage that discharges the hydraulic oil supplied to the pressure receiving chamber to reduce the preset pressure. A second shut-off valve which is interposed in the third oil passage and opens the third oil passage when the oil pressure in the drain oil passage is higher than a predetermined exhaust oil pressure; and a downstream side of the pressure adjusting valve in the first oil passage. And a third shut-off valve which is interposed in the portion and shuts off the first oil passage when the internal pressure of the pressure receiving chamber is lower than a predetermined value. Hydraulic impact tool, wherein the door.