JP3356416B2 - Hitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a striking device such as a hydraulic breaker for striking a tool with a piston by reciprocating the piston using fluid pressure.

[0002]

2. Description of the Related Art As a striking device for striking a tool with a piston by reciprocating the piston using fluid pressure, there is, for example, a hydraulic breaker shown in FIG. This hydraulic breaker is used, for example, as an attachment attached to an arm of a shovel car instead of a bucket, and crushes an object by a chisel (tool) using the impact force of a piston. Here, FIG. 5 is a cross-sectional view showing the structure of the hydraulic breaker and each step of the striking operation, (a) showing a step of retracting the piston, (b) showing a state in which the piston is at a retracted position, (C) shows the step of striking the piston, and (d) shows the state at the time of striking.

A hydraulic breaker 31 includes a hydraulic cylinder 33 for reciprocating a piston 32 by hydraulic pressure of hydraulic oil supplied from a hydraulic pump or the like, and a direction / flow control valve 34 for controlling the inflow and outflow of hydraulic oil to and from the hydraulic cylinder 33.
(Control valve). The direction / flow control valve 34 is
A hydraulic pump or the like (not shown) is connected to the hydraulic oil supply port A, and a hydraulic oil tank or the like (not shown) is connected to the hydraulic oil discharge port B. The hydraulic cylinder 33 has an insertion hole 35 formed from the front end to the rear end. In the insertion hole 35, a piston 32 having a flange 32 a at a substantially intermediate position in the longitudinal direction is provided with a longitudinally extending portion of the insertion hole 35. It is inserted movably in the direction, and is located at the distal end side of the insertion port 35 at the distal end side of the piston 32, that is, in front of the piston 32 in the impact direction.
The chisel 37 (tool) is mounted with a part inserted.

At a substantially intermediate position in the longitudinal direction of the insertion hole 35,
A first chamber 33a and a second chamber 33b partitioned by a flange 32a of the piston 32 are provided. These first and second chambers 33a and 33b are provided with a direction / flow control valve 34.
And are also connected to a hydraulic pump, a hydraulic oil tank, and the like, respectively. Here, the direction / flow rate control valve 34 inflows hydraulic fluid into the first chamber 33a located forward in the impact direction with respect to the flange 32a of the piston 32 and the second chamber 33b located backward in the impact direction. And the reciprocating movement of the piston 32 by controlling the outflow. At the rear end of the insertion opening 35, a pressure chamber 36 is formed, which is hermetically partitioned from the second chamber 33b by the rear end of the piston 32. The pressure chamber 36 is filled with a high-pressure gas (nitrogen gas or the like), and applies pressure to the piston 32 in the direction of impact by the internal pressure.

The chisel 37 has a notch 37 having a predetermined length along the striking direction at a portion to be inserted into the insertion hole 35.
a is provided, and the chisel 37 is
When a retainer pin 38 having a smaller dimension in the hitting direction than the notch 37a is inserted into the notch 37a in a state where a part thereof is inserted into the notch 37a, a stroke of a predetermined distance is possible along the hitting direction to be mounted. Have been.

Hereinafter, the impact operation of the hydraulic breaker 31 will be described. First, the piston 32 and the chisel 37
Figure 5
As shown in (a), the tip of the chisel 37 is pressed against an object such as a pavement surface of the road or the ground to be retracted together with the piston 32, and this is used as an opportunity to trigger the direction / flow control valve 3.
The hydraulic oil is sent from the hydraulic oil supply port A into the first chamber 33a through the fourth port 4. As a result, the internal pressure of the first chamber 33a rises, and the piston 32 is further retracted.
The gas in the pressure chamber 36 is compressed by the rear end of 2 and the internal pressure rises. Then, when the piston 32 is retracted to a predetermined position as shown in FIG. 5B, the direction / flow control valve 34 is operated to transfer the hydraulic oil in the first chamber 33a to the second chamber 33b and the hydraulic oil. It is discharged to the discharge port B to reduce its internal pressure. Thereby, the hydraulic pressure in the first chamber 33a is released, and the piston 32 is moved in the striking direction by the differential pressure between the internal pressure of the pressure chamber 36 and the internal pressure of the first chamber 33a (see FIG. 5C). Then, as shown in FIG. 5D, the chisel 37 is hit by the piston 32,
The target object is crushed by the chisel 37 using the impact force of 2. After performing the hitting operation in this manner, the above-described steps are repeated again to continuously perform the hitting operation.

[0007]

The conventional hydraulic breaker 3
In 1, both the piston 32 and the chisel 37 are made of metal and have a structure in which the chisel 37 is directly struck by the piston 32. Therefore, the striking sound of the piston 32 striking the chisel 37 is loud, causing a noise problem. In addition, the piston 32 and the chisel 37 were easily worn.

The present invention has been made in view of such circumstances, and has as its object to provide a striking device that can reduce noise and extend the life of a piston and a tool.

[0009]

According to a first aspect of the present invention, there is provided a striking apparatus for striking a tool with a piston by reciprocating the piston by using a fluid pressure. A fluid chamber containing a liquid is provided between the tool and the tool, and the piston is arranged to strike the tool via the liquid. In the hitting device configured as described above, the piston hits the tool via the liquid, so that the hitting sound can be reduced and the noise can be reduced. Also,
Since the piston does not strike the tool directly, wear on the piston and the tool can be reduced and their life can be extended.

According to a second aspect of the present invention, the first chamber and the second chamber separated by a flange provided on the piston, and the inflow and outflow of fluid to and from the first and second chambers. A control valve for controlling the reciprocating movement of the piston, and a control valve provided between the fluid chamber and the tool, wherein the tip of the piston is housed and the liquid is liquid-tight between the tip of the piston. And a spacer having a receiving hole for sealing the piston, and transmitting the impact force of the piston to the spacer and the tool via the liquid in the receiving hole. In the hitting device configured as described above, since the tool is independent of the fluid chamber, the tool can be easily replaced. Further, since the liquid is sealed between the tip of the piston and the receiving hole of the spacer, the liquid does not easily escape when the piston is hit, and the striking force of the piston is efficiently transmitted to the spacer and the tool via the liquid. it can.

According to a third aspect of the present invention, in the hitting device, a flow hole communicating the fluid chamber with the second chamber located rearward in the hitting direction with respect to the flange of the piston is provided. . In the striking device, when the piston moves along the striking direction, the volume of the fluid chamber changes and the internal pressure changes, acting as a resistance to the movement of the piston. In the striking device of the present invention, the volume of the fluid chamber is increased by the piston retreating in the striking direction opposite to the second chamber located in the striking direction with respect to the flange of the piston, that is, the fluid chamber. It is communicated with a chamber that becomes smaller and has a larger volume as the piston advances. Thereby, even if the piston moves backward and the volume of the fluid chamber increases, fluid is supplied from the second chamber to reduce the decrease in the internal pressure of the fluid chamber, and the piston advances to reduce the volume of the fluid chamber. Even if
Since the fluid in the fluid chamber escapes to the second chamber, an increase in the internal pressure of the fluid chamber is reduced, and the resistance to the movement of the piston can be reduced.

According to a fourth aspect of the present invention, in the hitting device, the fluid chamber is connected to a pressure-holding means for taking in and out the liquid to reduce a change in the internal pressure. In the hitting device configured as described above, even if the volume of the fluid chamber changes due to the movement of the piston, the liquid is taken in and out of the fluid chamber by the pressure-holding means, so that the change in the internal pressure of the fluid chamber is reduced. You.

According to a fifth aspect of the present invention, the impact chamber is characterized in that the fluid chamber is sealed and a gas is sealed in addition to the liquid. In a striking device configured in this way, even if the volume of the fluid chamber changes due to the movement of the piston, the gas expands or compresses. Thus, the change in the internal pressure of the fluid chamber is reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An example in which the hitting device of the present invention is applied to a hydraulic breaker will be described below with reference to FIG. Here, the same or similar parts as those of the above-described conventional hydraulic breaker 31 will be described using the same reference numerals. FIG. 1 is a sectional view showing the structure of a hydraulic breaker according to the present invention;
FIG. 2 is a sectional view showing each step of a striking operation of the hydraulic breaker of the present invention, wherein (a) shows a step of retracting a piston,
(B) shows a state in which the piston is at the retracted position, and (c)
Shows a step of striking the piston, and (d) shows a state at the time of striking. The hydraulic breaker 1 includes a hydraulic cylinder 2 that reciprocates a piston 32 in a striking direction by hydraulic pressure of hydraulic oil supplied from a hydraulic pump or the like, and a direction / flow rate control that controls inflow and outflow of hydraulic oil to and from the hydraulic cylinder 2. And a valve 34. The direction / flow control valve 34 is
A hydraulic pump or the like (not shown) is connected to the hydraulic oil supply port A, and a hydraulic oil tank or the like (not shown) is connected to the hydraulic oil discharge port B. The hydraulic cylinder 2 has an insertion hole 35 formed from the front end to the rear end.
Piston 3 having flange 32a at a substantially middle position in the longitudinal direction
2 is inserted movably in the longitudinal direction of the insertion hole 35, and a chisel 37 is located at the tip side of the insertion port 35, located at the tip side of the piston 32, that is, in front of the piston 32 in the impact direction. It is mounted with the part inserted.

At a substantially middle position in the longitudinal direction of the insertion hole 35, that is, a substantially middle position in the striking direction of the piston 32, a first chamber 2a and a second chamber 2b separated by a flange 32a of the piston 32 are provided. Have been. The first chamber 2a is connected to the direction / flow control valve 34 through a front end side flow path P1 provided on the side wall at the front end in the impact direction, and the second chamber 2b is provided at the rear end provided at the rear end in the impact direction. The side flow path P2 is connected to the direction / flow control valve 34. Tip side flow path P1
Is closed by the flange 32a of the piston 32 in a state where the piston 32 is advanced to the maximum in the striking direction, and the rear end side flow path P2 is always connected to the hydraulic oil discharge port B. . In the hydraulic cylinder 2, a side wall of a substantially middle portion of a moving range of the flange portion 32a of the piston 32 includes:
An intermediate passage P3 communicating with the direction / flow control valve 34 is provided. The intermediate portion flow path P3 communicates with the second chamber 2b when the piston 32 is located closer to the first chamber 2a than at a substantially intermediate position in the striking direction. The chamber 32a is closed by the flange 32a of the piston 32 in other states.

The direction / flow control valve 34 controls the inflow and outflow of hydraulic oil into and out of the first chamber 2a and the second chamber 2b to reciprocate the piston 32. The valve 34a provided in the flow passage W to which the hydraulic oil discharge port B, the front end flow path P1, the rear end flow path P2, and the intermediate flow path P3 are connected is supplied from the intermediate flow path P3. By moving the oil according to the level of the oil pressure, the connection and blockage between the working oil supply port A, the working oil discharge port B, the front end flow path P1, and the rear end flow path P2 via the flow passage W are performed. is there.

At the rear end of the insertion port 35, a piston 3 is provided.
A pressure chamber 36 is hermetically partitioned from the second chamber 2b by the rear end of the second chamber 2b. The pressure chamber 36 is filled with a high-pressure gas (nitrogen gas or the like), and applies pressure to the piston 32 in the direction of impact by the internal pressure.

In a portion of the insertion hole 35 of the hydraulic cylinder 2 located between the tip of the piston 32 and the chisel 37, the enlarged diameter portion 3 is formed with a predetermined length along the striking direction. A spacer 4 is provided in the enlarged diameter portion 3. A first sealing member 6 for sealing the space between the spacer 4 and the inner wall of the enlarged diameter portion 3 in a liquid-tight manner is provided all around the outer periphery of the spacer 4, whereby a piston is provided in the enlarged diameter portion 3. 32 between the fluid chamber 7
Is formed. The first sealing material 6 is, for example, an O-ring or a piston ring mounted on a first groove 6a provided over the entire periphery of the spacer 4 and, if necessary, the striking direction of the spacer 4 One or more stages are provided. A vent hole h communicating with the outside of the hydraulic cylinder 2 is formed at the distal end side of the enlarged diameter portion 3, so that when the spacer 4 advances or retreats along the hitting direction in the enlarged diameter portion 3. Spacer 4 at the enlarged diameter portion 3
The change in the internal pressure in the space on the tip side than the
The resistance to the movement of the object is not generated.

The spacer 4 has a base 4 a formed in a substantially cylindrical shape having a larger diameter than the piston 32, and a chisel 37 of the base 4.
On the side, a protruding end portion 4b formed in a substantially cylindrical shape having the same diameter and the same diameter as the piston 32 is provided. The base 4a is formed with an accommodation hole 4c having substantially the same diameter as the piston 32 and accommodating the tip of the piston 32. In the vicinity of the opening end of the housing hole 4c, a second sealing member 8 for sealing the tip end of the piston 32 and the housing hole 4c in an air-tight and liquid-tight manner is provided. The spacer 4 is pressed through the hydraulic oil in the space 4c. In the present embodiment, an O-ring or the like mounted in a second groove 8a formed over the entire periphery near the opening end of the accommodation hole 4c is used as the second sealing material 8. Here, if the second sealing material 8 is able to press the spacer 4 via the hydraulic oil while maintaining the liquid tightness between the distal end portion of the piston 32 and the accommodation hole 4c, the sealing material 8 is It may not be provided, and a very small gap may be formed between the piston 32 and the accommodation hole 4c. The fluid chamber 7 is filled with a liquid, and in the present embodiment, a hydraulic oil is used as the liquid. The fluid chamber 7 is provided in the hydraulic cylinder 2
The rear side of the second chamber 2b is connected to the rear side of the second chamber 2b through a flow hole 9 formed in the side wall of the fluid chamber 7 to connect the rear end of the second chamber 2b to the rear side in the impact direction. Hydraulic oil can come and go. Here, one or a plurality of the circulation holes 9 are provided on the side wall of the hydraulic cylinder 2.

The chisel 37 has a notch 37 having a predetermined length along the striking direction at a portion to be inserted into the insertion hole 35.
a is provided, and the chisel 37 is
When a retainer pin 38 having a smaller dimension in the hitting direction than the notch 37a is inserted into the notch 37a in a state where a part thereof is inserted into the notch 37a, a stroke of a predetermined distance is possible along the hitting direction to be mounted. Have been. Here, the movable range of the chisel 37 in the striking direction is the notch 37
a and the dimension difference between the retainer pin 38 and the striking direction. The chisel 37 is replaced with a chisel having a different shape depending on the use, or is replaced with a new one when worn out due to long-term use.

Hereinafter, the impact operation of the hydraulic breaker 1a configured as described above will be described. Here, at the start of the impact operation, the hydraulic oil supply port A and the front end side flow path P1
Is connected via the direction / flow control valve 34, but since the piston 32 is advanced to the maximum and the front end side flow path P1 is closed by the flange 32a of the piston 32, the first chamber 2a No hydraulic oil flows into. First, FIG.
(A), the piston 32 is brought close to the spacer 4 and the chisel 37 as shown by the two-dot chain line,
7 is pressed against the object, and the spacer 4 and the piston 32 are retracted together with the chisel 37 as shown by the solid line in FIG. Thereby, the flange 3 of the piston 32
The front-end side flow path P1 closed by 2a is opened and hydraulic oil is sent from the hydraulic oil supply port A into the first chamber 2a, and the internal pressure of the first chamber 2a rises.
2 is further retracted. By retracting the piston 32 in this manner, the gas in the pressure chamber 36 is compressed by the rear end of the piston 32, and the internal pressure increases.

Here, when the piston 32 retreats, the hydraulic oil in the second chamber 2b is pushed out to the hydraulic oil outlet B and the flow hole 9 by the flange 32a of the piston 32, so that the internal pressure of the second chamber 2b is reduced. The rise is suppressed, and the resistance to the movement of the piston 32 is reduced. Although the volume of the fluid chamber 7 is larger than that at the start of the striking operation, the hydraulic oil is supplied from the second chamber 2 b of the hydraulic cylinder 2 into the fluid chamber 7 through the flow hole 9. Is reduced, and the resistance of the piston 32 to the movement is reduced. Further, since the decrease in the internal pressure of the fluid chamber 7 is reduced, the spacer 4 remains at the position in contact with the chisel 37 even if the piston 32 is further retracted by the hydraulic cylinder 2.

When the piston 32 retracts to the maximum, the first chamber 2a and the intermediate passage P3 communicate with each other, and hydraulic oil flows into the intermediate passage P3.
Is moved to connect the front end side flow path P1, the rear end side flow path P2, and the hydraulic oil discharge port B, so that the hydraulic oil in the first chamber 2a is discharged and the internal pressure decreases. As a result, the hydraulic pressure in the first chamber 2a is released, and the piston 32 is moved in the hitting direction by the differential pressure between the internal pressure of the pressure chamber 36 and the internal pressure of the first chamber 2a (see FIG. 2C). Here, piston 3
The hydraulic oil is supplied from the fluid chamber 7 into the second chamber 2 b of the hydraulic cylinder 2 through the communication hole 9, so that the internal pressure of the fluid chamber 7 increases. Is reduced, and the decrease in the internal pressure of the second chamber 2b is also reduced, so that the resistance of the piston 32 to the movement is reduced.
The distal end of the piston 32 is
c, and strikes the spacer 4 via the hydraulic oil in the accommodation hole 4c (see FIG. 2D). At this time, the accommodation hole 4
Since the hydraulic oil in c is confined in the housing hole 4c by the second sealing material 8, the structure is such that the change in the internal pressure of the fluid chamber 7 is reduced, and the striking force of the piston 32 through the hydraulic oil is efficiently reduced. Is transmitted to the spacer 4.
Since the projecting end 4b of the spacer 4 remains in contact with the chisel 37, the chisel 37 receives the striking force of the piston 32 via the spacer 4, and the piston 4 as shown by a two-dot chain line in FIG. A stroke is made a predetermined distance in the striking direction together with the spacer 32 and the target is crushed by the chisel 37 using the striking force of the piston 32.

When the piston 32 advances, the intermediate passage P3 is connected to the second chamber 2b, and the hydraulic oil in the intermediate passage P3 flows out to reduce the internal pressure.
Moves to the position at the start of the striking operation, closes the front end side flow path P1, the rear end side flow path P2, and the hydraulic oil discharge port B, and connects the front end side flow path P1 and the hydraulic oil supply port A. . After performing the hitting operation of the chisel 37 in this manner, the above-described steps are repeated again to continuously perform the hitting operation of the chisel 37.

According to the hydraulic breaker 1a configured as described above, since the piston 32 hits the chisel 37 via the hydraulic oil, the hitting sound can be reduced and the noise can be reduced. Further, since the piston 32 does not directly hit the chisel 37, the wear of the piston 32 and the chisel 37 can be reduced, and the life thereof can be extended. The fluid chamber 7 has a piston 32 at the enlarged diameter portion 3 of the hydraulic cylinder 2.
Between the cylinder 32 and the chisel 3 because the chisel 37 is independent of the fluid chamber 7.
The replacement of the chisel 37 can be facilitated while using a hydraulic breaker having a structure having the fluid chamber 7 between the chisel 37. Since the change in the internal pressure of the fluid chamber 7 is reduced, the resistance to the movement of the piston 32 can be reduced.

[Second Embodiment] Next, a second embodiment will be described with reference to FIG. 3, but the same or similar parts as in the first embodiment of the present invention will be described. The description will be made using the reference numerals. 3A and 3B are cross-sectional views illustrating the steps of the structure and operation of the hydraulic breaker according to the second embodiment, in which FIG. 3A illustrates a piston retreating step, and FIG. 3B illustrates a piston striking step. I have. The hydraulic breaker 1b is different from the hydraulic breaker 1a shown in the first embodiment in that the fluid chamber 7 and the pressure maintaining means 11 are connected to the fluid chamber 7 instead of allowing the fluid chamber 7 to communicate with the second chamber 2a through the communication hole 9. Things. Here, in the present embodiment, the liquid filled in the fluid chamber 7 does not have to be hydraulic oil. The pressure-holding means 11 is partitioned into a first chamber S1 and a second chamber S2 in a pressure-resistant container 12 by a diaphragm 13 made of an elastic film such as rubber. A gas is sealed at a predetermined pressure in the first chamber S1 separated from the fluid chamber 7 by the pressure, and a predetermined amount of liquid is filled in the second chamber S2 communicated with the fluid chamber 7.

According to the hydraulic breaker 1b configured as described above, when the volume of the fluid chamber 7 increases due to the retreat of the piston 32 and the internal pressure of the fluid chamber 7 starts to decrease, the second pressure holding means 11 The diaphragm 13 is displaced to the second room S2 side to push out the liquid in the second room S2 into the fluid chamber 7, and the predetermined amount of the liquid is Is supplied, the decrease in the internal pressure of the fluid chamber is reduced. When the volume of the fluid chamber 7 decreases due to the advance of the piston 32 and the internal pressure of the fluid chamber 7 starts to increase, the internal pressure of the second chamber S2 of the pressure holding means 11 increases. Since the liquid is displaced toward the first chamber S1 and a predetermined amount of liquid is taken from the fluid chamber 7 into the second chamber S2, an increase in the internal pressure of the fluid chamber 7 is reduced.

[Third Embodiment] Next, a third embodiment will be described with reference to FIG. 4, but the same or similar parts as those of the first embodiment of the present invention are the same. The description will be made using the reference numerals. FIG. 4 is a cross-sectional view showing the steps of the structure and operation of the hydraulic breaker according to the third embodiment, where (a) shows a state in which the piston has advanced to the maximum,
(B) shows a state where the piston is retracted to the maximum.
In the hydraulic breaker 1c, in the hydraulic breaker 1a described in the first embodiment, the fluid chamber 7 is hermetically sealed, and a predetermined amount of gas g is sealed in the fluid chamber 7 in addition to the liquid f. Things. Here, in the present embodiment, the fluid chamber 7
The liquid filled therein may not be hydraulic oil. Accordingly, even if the volume of the fluid chamber changes due to the forward or backward movement of the piston 32, the gas is compressed or expanded, and the fluid chamber 7 is compared with the case where only the liquid is sealed in the fluid chamber 7. The change in the internal pressure is reduced.

[0029]

According to the present invention, the following effects can be obtained.
According to the first aspect of the present invention, since the piston strikes the tool via the fluid, the impact sound can be reduced and the noise can be reduced. In addition, since the piston does not directly hit the tool, wear of the piston and the tool can be reduced, and their life can be extended.

According to the second aspect of the present invention, since the spacer is provided between the fluid chamber and the tool, and the tool is independent of the fluid chamber, the tool can be easily replaced. Further, since the liquid is sealed between the tip of the piston and the receiving hole of the spacer, the liquid does not easily escape when the piston is hit, and the striking force of the piston is efficiently transmitted to the spacer and the tool via the liquid. it can.

According to the third aspect of the present invention, a change in the internal pressure of the fluid chamber caused when the piston moves is reduced, and the resistance to the movement of the piston can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a hydraulic breaker (a striking device) according to a first embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views illustrating each step of a striking operation of the hydraulic breaker according to the first embodiment, wherein FIG. 2A illustrates a step of retracting a piston, and FIG. 2B illustrates a state in which the piston is at a retracted position. (C) shows a piston striking process,
(D) shows the state at the time of impact.

FIG. 3 is a sectional view showing each step of the structure and operation of a hydraulic breaker according to a second embodiment of the present invention,
(A) shows a piston retreating process, and (b) shows a piston striking process.

FIG. 4 is a sectional view showing each step of the structure and operation of a hydraulic breaker according to a third embodiment of the present invention,
(A) shows the state where the piston has advanced to the maximum, and (b)
Indicates a state in which the piston has retreated as far as possible.

FIG. 5 is a sectional view showing a structure of a hydraulic breaker as an example of a conventional hitting device and respective steps of the hitting operation thereof.
(A) shows a piston retreating process, (b) shows a state where the piston is in a retreating position, (c) shows a piston striking process, and (d) shows a state at the time of striking.

[Explanation of symbols]

1a, 1b, 1c Hydraulic breaker (hitting device) 2a
First chamber 2b Second chamber 4 Spacer 4c Housing hole 7 Fluid chamber 9 Flow hole 11
Pressure holding means 32 Piston 32a
Flange 34 Direction / flow control valve (control valve) 37
Chisel (tool)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01B 11/04 B02C 1/00

Claims (5)

(57) [Claims] 1. A striking device for striking a tool with a piston by reciprocating a piston using fluid pressure, wherein a fluid chamber containing a liquid is provided between the piston and the tool. Wherein the piston is arranged to strike the tool via the liquid. 2. A first chamber and a second chamber partitioned by a flange provided on the piston, and a reciprocation of the piston by controlling inflow and outflow of a fluid to and from the first and second chambers. A control valve that moves, and a spacer that is provided between the fluid chamber and the tool and that has a receiving hole in which the tip of the piston is stored and in which the liquid is sealed in a liquid-tight manner between the tip of the piston. 2. The striking device according to claim 1, wherein the striking force of the piston is transmitted to the spacer and the tool via the liquid in the receiving hole. 3. The striking device according to claim 2, wherein a flow hole communicating the fluid chamber with the second chamber located rearward in the striking direction with respect to the flange of the piston is provided. 4. The striking device according to claim 2, wherein the fluid chamber is connected to a pressure-holding means for taking in and out the liquid to reduce a change in the internal pressure. 5. The fluid chamber is sealed,
3. The striking device according to claim 2, wherein a gas is sealed in addition to the liquid.