JP2013233595A - Fluid pressure hammering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure hammering device capable of automatically adjusting a stroke of a piston according to the quality of rock to be crushed.SOLUTION: A stroke-switching pilot hole (40) for removing high fluid pressure during hammering is provided in a reversal chamber (5), and a short stroke is switched to a long stroke by switching over a stroke switching valve (30) after a fluid is successively accumulated in an accumulator (32) provided in the stroke switching valve (30) by a fluid ejection valve (41) that operates by incurring the fluid pressure from the stroke-switching pilot hole (40).

Description

  The present invention relates to a hydraulic-type hammering device such as a hydraulic type, and in particular, a hydraulic-type hammering device capable of automatically increasing a hammering force when a crushed material such as a rock is hard and does not break even when hit for a certain time. It is about.

When crushing a rock or the like using a hydraulic hitting device, the tip of the chisel of the hitting device is pressed against the crushed material, and the rear end of the chisel is continuously hit by a reciprocating motion of a piston inserted in the hitting device.
As for the striking force when the piston strikes the chisel, a larger striking force can be obtained by reciprocating the piston with a longer stroke when the thrust for urging the piston forward is equal.
There are various types of rocks, from soft rocks to hard rocks. When it is hard, the crushing operation can be performed efficiently by lengthening the stroke of the piston and operating it in a mode in which the number of hits is small but the hitting force is strong.

Conventionally, as a method for automatically adjusting the stroke of the piston of the fluid pressure type striking device according to the hardness of the rock mass, when the rock mass is soft and the amount of biting into the rock of the chisel is large, the piston moves from a predetermined striking position. A method has also been proposed in which the stroke is switched by detecting the forward movement. (Patent Document 1)
Furthermore, a method has been proposed in which the stroke is switched by utilizing the difference in pressure difference between the upper and lower chambers of the piston due to the difference in hardness of the crushed material. (Patent Document 2)

JP2003-311651 JP 2005-177899 A

  Switching the stroke by detecting that the piston has advanced from a predetermined striking position disclosed in Patent Document 1 does not mean that the cylinder in which the piston is inserted is spatially fixed in actual work. Since the piston is pushed against the crushed material by a hydraulic excavator, etc., the piston moves forward from a predetermined striking position when the crushed material begins to break, but at the same time the cylinder itself moves forward by the pressing force of the hydraulic excavator, etc. Therefore, the moving distance that the piston moves forward from the predetermined striking position becomes very delicate, and it is difficult to reliably detect that the chisel bites into the crushed material, and it is difficult to perform accurate stroke control.

Further, in the method of switching the stroke based on the pressure difference between the upper and lower chambers of the piston disclosed in Patent Document 2, the pressure generated in each chamber at the time of striking is not only the hardness of the rock mass but also the oil temperature, viscosity, etc. Because it is affected, it is difficult to accurately detect the difference in generated pressure when striking hard rock and soft rock, and there is a problem that the switching of the stroke due to this difference becomes very unstable. .
Therefore, the present invention provides a fluid pressure striking device that eliminates such a problem.

The fluid pressure striking device of the present invention has a striking piston having a striking pressure receiving surface and a return pressure receiving surface inserted in a cylinder so as to be able to reciprocate, so that a high pressure is always applied to the return pressure receiving surface, and the striking pressure receiving surface. The piston is reciprocated by alternately switching between high pressure and low pressure, and the stroke of the piston can be switched between a short stroke and a long stroke by a stroke switching valve.
Further, the fluid pressure type striking device is provided with a stroke switching pilot hole for taking out a high-pressure fluid pressure generated in the reversing chamber when the piston is struck, and receives the fluid pressure from the stroke switching pilot hole. The fluid is sequentially accumulated in the pressure accumulating chamber provided in the stroke switching valve by the operating fluid discharge valve, and the stroke switching valve is sequentially moved according to the accumulated amount to switch from the short stroke to the long stroke.
In the fluid pressure striking device according to the second aspect, the time for switching from the short stroke to the long stroke can be selected by adjusting the movable stroke of the spool in the fluid discharge valve.

  The fluid pressure striking device of the present invention can efficiently perform a crushing operation by automatically switching to a stronger long stroke when the crushing operation is not crushed even if continuously struck for a certain time.

1 is a schematic view of a fluid pressure striking device. It is a figure at the time of piston raising (at the time of an operation start). It is a figure at the time of the piston fall start at the time of a short stroke. It is a figure during piston descent at the time of a short stroke. It is a figure in the time of the piston raising at the time of a short stroke. It is a figure in piston descending after switching to a long stroke. It is a figure in the time of piston raising at the time of a long stroke. It is a figure at the time of the piston fall start at the time of a long stroke. (A) shows a unit, and (B) shows a simple unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a hydraulic striking device showing an embodiment of the present invention, and FIGS. 2 to 8 sequentially show states of operation of the striking device of the present invention.
In the hydraulic striking device of the present invention, a piston 2 is inserted into a cylinder 1 so as to be capable of moving back and forth in the axial direction, a chisel 3 is mounted in front of the piston 2 (left side in the drawing), and a rear end portion of the piston 2 ( On the right side of the figure, there is provided a gas chamber 4 for energizing the piston 2 at the time of impact, for example, containing a gas such as nitrogen.

Further, in this striking device, a main switching valve 20 for switching the forward / backward movement of the piston 2, a stroke switching valve 30 for switching the stroke of the piston 2, and a fluid pressure signal for operating the stroke switching valve to switch the stroke are generated. And a pressure control valve 43 that regulates the fluid pressure of the fluid flowing into the pilot port 33 of the stroke switching valve 30.
The piston 2 includes a small diameter portion 2a, a first large diameter portion 2b, an intermediate portion 2c, a second large diameter portion 2d having the same diameter as the first large diameter portion, and an intermediate diameter portion 2e in order from the right shown in FIG. The diameter of the middle diameter part 2e is larger than the diameter of the small diameter part 2a and is smaller than the diameters of the large diameter parts 2b and 2d. The right end surface of the first large diameter portion 2b is a ring-shaped impact pressure receiving surface 2u, and the left end surface of the second large diameter portion 2d is a ring-shaped return pressure receiving surface 2v.

  A reversing chamber 5, a constant low pressure chamber 11, a long pilot chamber 12, a short pilot chamber 13, and a constant high pressure chamber 7 are formed in a ring-shaped groove on the inner wall of the piston sliding portion of the cylinder 1 from the right side of the figure. Yes. Also, the arrangement positions of the constant high pressure chamber 7, the short pilot chamber 13, the long pilot chamber 12, and the constant low pressure chamber 11 are arranged to switch the main switching valve 20 according to the operating state of the piston 2 described later. is there. That is, the high-pressure chamber 7 is always in communication with or disconnected from the short pilot chamber 13 or the long pilot chamber 12 depending on the position of the piston 2 during reciprocating movement, and the low-pressure chamber 11 is always in communication with or out of communication with the long pilot chamber 12. It is arranged to become.

The hydraulic pump 10 serving as a hydraulic source is connected to a switching valve 53 that is switched by a pedal 51. When the pedal 51 is depressed, the high-pressure pipe 55 is connected to the discharge side of the hydraulic pump 10 by the switching valve 53. When the high pressure chamber 7 is always in a high pressure state and the pedal 51 is not depressed, the high pressure pipe 55 is connected to the low pressure pipe 52 and becomes a low pressure side (see FIG. 1).
Similarly, the oil tank 50 is always connected to the low-pressure chamber 11 via the low-pressure pipe 52 and can be switched between the state communicating with the reversing chamber 5 and the state shut off via the main switching valve 20. It is configured. That is, the main switching valve 20 is configured to be switched so that the reversing chamber 5 communicates with either the high pressure hydraulic pump 10 or the low pressure oil tank 50.

High pressure oil can be applied to one pilot port 20A of the main switching valve 20, the other pilot port 20B is connected to the long pilot chamber 12, and the long pilot chamber 12 is either high pressure oil or low pressure oil. As a result, the main switching valve 20 is switched.
That is, when high pressure oil acts on the pilot port 20B, the main selector valve 20 moves the spool of the main selector valve 20 to the right side in the figure so that the high pressure port 20b and the reverse port 20c communicate with each other. The high pressure oil applied to the pilot port 20A is pushed back to the left in the figure so that the low pressure port 20a and the reverse port 20c communicate with each other.

  The stroke switching valve 30 includes a spool 31 and a spring inserted therein, and a pressure accumulating chamber 32 is provided inside the stroke switching valve 30 at a position opposed to a spring that applies a pressing force to the spool 31. When the pressure in the pressure accumulating chamber 32 is below a certain value, the spool 31 is pushed rightward by the force of the spring, and the long pilot port 30b and the short pilot port 30c communicate with each other, while the pressure in the pressure accumulating chamber 32 is reduced. When the spring is lifted and a force stronger than the spring is pressed against the spool, the spool moves to the left in the figure, and the long pilot port 30b and the short pilot port 30c are blocked. The stroke switching valve 30 is a spring type, but various types such as a hydraulic type and a gas type are selected.

Further, in order to take out a pilot signal for stroke switching, a stroke switching pilot hole 40 is provided in the reversing chamber 5, and the stroke switching pilot hole 40 is connected to a fluid discharge valve 41. The fluid discharge valve 41 discharges a small amount of fluid when receiving a high fluid pressure from the stroke switching pilot hole 40, and the fluid flows to the pressure control valve 43 to control the fluid pressure. In addition, the amount of liquid accumulated in the pressure accumulating chamber 32 can be adjusted by the variable throttling 45. That is, since the amount of oil accumulated in the pressure accumulating chamber 32 can be adjusted by adjusting the variable throttle 45, the time for switching from a short stroke to a long stroke, which will be described later, can be adjusted.
A check valve 42 is provided that shuts off when the fluid discharge valve 41 discharges fluid and communicates with the fluid discharge valve 41 when fluid is supplied to the fluid discharge valve 41.

Further, when the striking device is in operation, the fluid pressure stored in the pressure accumulating chamber 32 is held, and when the operation stops, the spool 31 is opened by opening the pressure accumulating chamber 32 to always communicate with the low pressure chamber 11. A pilot port operation check valve 44 for returning to the initial state is provided.
The pilot port operation check valve 44 is disconnected from the pressure accumulating chamber 32 and the low-pressure chamber 11 at all times when high-pressure oil is acting, and communicates when the low-pressure oil acts.
Accordingly, in order to return the spool 31 to the initial state (short stroke), the fluid pressure in the pressure accumulating chamber 32 is always communicated with the low pressure chamber 11 via the pilot port operation check valve 44, and the pressure accumulating pressure is increased. Since the fluid pressure in the chamber 32 can communicate with the oil tank 50 via the variable throttle 45, the spool 31 can be returned to the initial state (short stroke) more reliably by the variable throttle 45.

Next, referring to FIG. 2 to FIG. 8, when the hydraulic pressure striking device according to the present invention is operated with a short stroke at the start of striking and the crushed material is hard and does not crush even if struck for a certain period of time, the striking force automatically A striking operation that switches to an operation with a large long stroke will be described.
FIG. 2 is a view at the start of operation, and the chisel 3 is pressed against the crushed material by a hydraulic excavator or the like through the cylinder 1. Further, the piston 2 inserted in the cylinder 1 is located at the forward end (spot) by its own weight.

Since the spool 31 inserted in the stroke switching valve 30 is moved to the right in the figure by the force of the spring, the short pilot chamber 13 and the long pilot chamber 12 are in communication.
The spool of the fluid discharge valve 41 connected to the stroke switching pilot hole 40 provided in the reversing chamber 5 is pushed upward in the figure by the force of the spring.
When the hydraulic pump 10 is driven and the pedal 51 is continuously depressed, the high-pressure fluid discharged from the hydraulic pump 10 flows into the pilot port 20A of the main switching valve 20 by the switching valve 53, while the pilot of the main switching valve 20 is driven. Since the port 20B is always in the low pressure chamber 11 through the long pilot chamber 12 and is in a low pressure, the spool of the main switching valve 20 moves to the left side in the figure, the low pressure port 20a and the reversing port 20c communicate, and the reversing chamber 5 Since it communicates with the oil tank 50, the pressure is low.

Further, the high-pressure fluid always flows into the high-pressure chamber 7 through the high-pressure pipe 55 and acts on the pilot port of the pilot operation check valve 44 to block the pilot operation check valve 44.
The high pressure oil that has always flowed into the high pressure chamber 7 acts on the return pressure receiving surface 2v and generates an upward force (right direction in the figure), while the pressure in the reversing chamber 5 acting on the impact pressure receiving surface 2u is low. The piston 2 starts to rise (right direction in the figure).

When the piston 2 rises and the return pressure receiving surface 2v reaches the position of the short pilot chamber 13, the high-pressure fluid in the high-pressure chamber 7 always flows from the short pilot chamber 13 to the short pilot port 30c and the long pilot port 30b of the stroke switching valve 30. The long pilot chamber 12 flows into the pilot port 20B of the main switching valve 20 through the piping and the piping 23, and the spool of the main switching valve 20 moves to the right side in the figure by the action of this high-pressure fluid.
For this reason, the high pressure port 20b and the reversing port 20c of the main switching valve 20 communicate with each other, the high pressure fluid from the hydraulic pump 10 flows into the reversing chamber 5 through the reversing pipe 22, and the reversing chamber 5 becomes high pressure. (Figure 3)
For this reason, high pressure oil acts on both the pressure receiving surface 2u for impact and the pressure receiving surface 2v for return, but the pressure receiving area of the pressure receiving surface 2u for impact is formed larger than the pressure receiving area of the pressure receiving surface 2v for return. The force to move the piston 2 downward (leftward in the figure) becomes large, and the piston 2 is lowered (leftward in the figure) by being energized by the pressure of nitrogen gas or the like enclosed in the gas chamber 4 disposed behind the piston 2. And gradually accelerate and hit the chisel 3.

At the position where the piston 2 strikes the chisel 3 (at the point of hitting), the low pressure chamber 11 and the long pilot chamber 12 are always communicated via the communication chamber 6, and the long pilot chamber 12 is connected to the pilot port of the main switching valve 20 via the pipe 23. Since it communicates with 20B, the pilot port 20B has a low pressure, and the spool of the main switching valve 20 moves to the left in the figure.
For this reason, the low pressure port 20a and the reverse port 20c of the main switching valve 20 communicate with each other, and the reverse chamber 5 connected to the reverse port 20c via the reverse pipe 22 becomes low pressure, returning to the state of FIG.
As described above, by repeating the operations of FIGS. 2 to 5, the piston 2 continuously strikes the chisel 3 with a short stroke (the return pressure receiving surface 2 v is turned back at the position of the short pilot chamber 13).

Next, the principle that the stroke of the piston 2 is automatically switched to the long stroke after the above-described continuous short stroke is repeated for a certain time will be described below.
During the stroke of the piston 2 (moving leftward in the figure), the high-pressure fluid that has flowed into the reversing chamber 5 flows into the fluid discharge valve 41 through the stroke switching pilot hole 40.
When this high-pressure fluid acts on the spool of the fluid discharge valve 41, the spool moves downward in the figure and pushes the fluid accumulated in the inside at a high pressure. The high pressure fluid pushed out from the fluid discharge valve 41 is always blocked by the check valve 42 in the direction of the low pressure chamber 11 and does not flow. The amount discharged from the variable throttle valve 45 is adjusted, and the pressure control valve 43 is adjusted. Then, it flows into the animal pressure chamber 32 from the pilot port 33 of the stroke switching valve 30.
At this time, high pressure is acting on the pilot port of the pilot operation check valve 44 inserted between the pilot port 33 of the stroke switching valve 30 and the low pressure chamber 11 at all times. The valve 44 is shut off. (Fig. 4)

After the piston 2 hits the chisel 3, when the return stroke (moving in the right direction in the figure) is reached, the reversing chamber 5 becomes low pressure, so the spool of the fluid discharge valve 41 connected to the reversing chamber 5 is While being pushed back, the fluid is always supplied from the low pressure chamber 11 through the check valve 42 into the fluid discharge valve 41.
During the return stroke of the piston, the pressure in the low pressure chamber 11 always slightly increases, but the pressure control valve 43 is adjusted so that the fluid pressure generated at this time does not act on the pilot port 33 of the throttle valve switching valve 30 (FIG. 5).

As described above, in the striking stroke of the piston 2, the fluid discharged from the fluid discharge valve 41 sequentially flows into the pressure accumulating chamber 32 of the stroke switching valve 30, and the fluid is always discharged from the low pressure chamber 11 in the return stroke. By repeating the operation of being supplied to 41, the fluid is accumulated in the pressure accumulating chamber 32, and the stroke switching valve moves according to the accumulated amount to switch from the short stroke to the long stroke. That is, the fluid accumulated in the pressure accumulating chamber 32 is repelled by the spring pushing the spool 31 inserted in the stroke switching valve 30 in the right direction in the figure, and the spool 31 sequentially moves in the left direction in the figure, and the short pilot chamber 13 The short pilot port 30c connected to the long pilot port 30b and the long pilot port 30b connected to the long pilot chamber 12 (the pilot port 20B of the main switching valve 20) are blocked (FIG. 6).
The time until switching from the short stroke to the long stroke is adjusted by changing the discharge amount for each stroke by adjusting the movable stroke of the spool in the fluid discharge valve 41 or by adjusting the variable throttle valve 45. Alternatively, the amount flowing into the pressure accumulating chamber 32 can be changed by adjusting both.

The piston 2 immediately after striking starts to rise (rightward in the drawing) because the reversing chamber 5 is at a low pressure and the pressure applied to the striking pressure receiving surface 2u is low. At this time, even if the return pressure receiving surface 2v reaches the position of the short pilot chamber 13 during the ascending process of the piston 2, the short pilot port 30c and the long pilot port 30b of the stroke switching valve 30 are in a disconnected state, and the long pilot chamber 12 Since the pressure of the pilot port 20B communicating with the (long pilot port 30b) via the pipe 23 does not change, the main switching valve 20 is not switched, and the return pressure receiving surface 2v of the piston 2 is positioned at the position of the short pilot chamber 13. And continue to rise (right direction in the figure) (FIG. 7).
When the return pressure receiving surface 2v reaches the position of the long pilot chamber 12, the high-pressure fluid constantly flowing into the high-pressure chamber 7 is transferred from the long pilot chamber 12 to the pilot port 20B of the main switching valve 20 via the pipe 23. The pilot port 20B becomes high pressure, the spool of the main switching valve 20 is switched, and moves to the right side in the figure.
For this reason, the high pressure port 20b and the reversing port 20c of the main switching valve 20 communicate with each other, the high pressure fluid discharged from the hydraulic pump 10 flows into the reversing chamber 5 through the reversing pipe 22, and the reversing chamber 5 has a high pressure (see FIG. 8).

High pressure is applied to the pressure receiving surface 2u for impact, and the piston 2 starts to descend (in the left direction in the figure), and is further urged by nitrogen gas or the like enclosed in the gas chamber 4 to gradually accelerate and strike the chisel 3 To do.
At the position where the piston 2 strikes the chisel 3 (spot), the low pressure chamber 11 and the long pilot chamber 12 are always in communication with each other via the communication chamber 6, and the long pilot chamber 12 is connected to the pilot port 20 </ b> B of the main switching valve 20. Because of the communication, the pilot port 20B has a low pressure, and the spool of the main switching valve 20 moves to the left side in the figure. For this reason, the low pressure port 20a and the reverse port 20c of the switching valve communicate with each other, the reverse chamber 5 connected to the reverse port via the reverse pipe 22 becomes low pressure, and the piston 2 starts to rise again.

By repeating the above operation, the piston 2 causes the chisel 3 to move with a long stroke (the return pressure receiving surface 2v is folded back at the position of the long pilot chamber 12) while the spool 31 of the stroke switching valve 30 is located on the left side in the figure. Strike continuously.
When the long stroke is repeated, if the crushed material breaks or the like, when the pedal 51 installed on the discharge side of the hydraulic pump 10 is stopped, the high pressure pipe 55 is connected to the low pressure pipe 52 by the switching valve 53. And the supply of the high-pressure fluid to the striking device is stopped to stop the driving of the striking device, and the supply of the high-pressure fluid to the pilot port of the pilot operation check valve 44 is also stopped. The valve 44 is opened, and the high-pressure fluid in the pressure accumulation chamber 32 of the stroke switching valve 30 always flows out to the low-pressure chamber 11 via the pilot operation check valve 44 or in the pressure accumulation chamber 32 via the variable throttle valve 45. Are allowed to escape to the oil tank 50 or flow out to both.

For this reason, the spool 31 is moved to the right in the figure by the force of the spring, and the stroke switching valve 30 is reset to the initial state (the short pilot port 30c and the long pilot port 30b are in communication).
Therefore, when the striking device is actuated by depressing the pedal 51 at the start of the next operation, the striking device starts from the short stroke striking in the state shown in FIGS.
The variable throttle valve 45 can adjust the time from the short stroke to the long stroke by adjusting the flow rate into the pressure accumulating chamber 32, and can reliably switch from the long stroke to the short stroke.

  As described above, when the crushed material is crushed within a certain time, the long stroke with a large number of strikes is performed. By switching to, more efficient crushing work can be performed.

Next, FIG. 9 shows the unit 100 (FIG. 9A) and the simplified unit 100A (FIG. 9B), and allows the hydraulic striking device to be easily used properly depending on the purpose of use.
That is, FIG. 9A is the same as FIG. 1 and shows a unit 100 that can automatically convert from a short stroke to a long stroke, and FIG. 9B shows a simple unit 100A that is used as a long stroke.
The unit 100 shown in FIG. 9A includes the stroke switching valve 30, the fluid discharge valve 41, the check valve 42, the pressure control valve 43, the pilot operation check valve 44, piping, and the like shown in FIG. When the unit 100 is connected, the hydraulic striking device can automatically convert from a short stroke to a long stroke.

  On the other hand, the simplified unit 100A shown in FIG. 9B does not include the stroke switching valve 30, the fluid discharge valve 41, the check valve 42, the pressure control valve 43, and the pilot operation check valve 44, and the stroke. Pipes connected to the switching pilot hole 40, the constant high pressure chamber 7, the constant low pressure chamber 11, the short pilot chamber 13, and the like are closed.

The hydrostatic striking device when the unit 100 is installed can automatically convert from a short stroke to a long stroke as already described above.
On the other hand, when the simple unit 100A is installed, the high-pressure pipe 55 is connected to the discharge side of the hydraulic pump 10 via the pedal 51, and the high-pressure chamber 7 is always in a high-pressure state. Further, the reversing chamber 5 becomes high pressure via the main switching valve 20, and high pressure oil acts on both the impact pressure receiving surface 2u and the return pressure receiving surface 2v. However, the pressure receiving area of the impact pressure receiving surface 2u is as follows. Since it is formed larger than the pressure receiving area of the return pressure receiving surface 2v, the force to move the piston 2 downward (to the left in the figure) becomes large, and nitrogen gas sealed in the gas chamber 4 disposed behind the piston 2 or the like. The piston 2 starts to descend (in the left direction in the figure) and is gradually accelerated to strike the chisel 3.

Further, at the position where the piston 2 strikes the chisel 3 (at the point of hitting), the low pressure chamber 11 and the long pilot chamber 12 are always communicated via the communication chamber 6, and the long pilot chamber 12 is connected to the main switching valve 20 via the pipe 23. Since the pilot port 20B communicates with the pilot port 20B, the pilot port 20B has a low pressure, and the spool of the main switching valve 20 moves to the left side in the figure. For this reason, the low pressure port 20a of the main switching valve 20 and the reverse port 20c communicate with each other, the reverse chamber 5 connected to the reverse port 20c via the reverse pipe 22 becomes low pressure, and the piston 2 starts to rise again. .
The piston 2 repeats the long stroke operation in which the return pressure receiving surface 2v rises until it reaches the long pilot chamber 12, and then starts to descend.
As described above, when the unit 100 is set in the fluid pressure striking device, the striking device can be automatically converted from a short stroke to a long stroke. When the simple unit 100A is provided, the striking device has a long stroke. Can easily cope with the situation.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 2a Small diameter part 2b 1st large diameter part 2c Intermediate | middle part 2d 2nd large diameter part 2e Medium diameter part 2u Impact pressure receiving surface 2v Return pressure receiving surface 3 Chisel 4 Gas chamber 5 Reversing chamber 6 Communication chamber 7 Always high pressure Chamber 10 Hydraulic pump 11 Normal low pressure chamber 12 Long pilot chamber 13 Short pilot chamber 20 Main switching valve 20A Pilot port (always high pressure)
20B Pilot port (reverse)
20a Low pressure port 20b High pressure port 20c Reversing port 22 Reverse piping 30 Stroke switching valve 30a Low pressure port 30b Long pilot port 30c Short pilot port 31 Spool 32 Pressure accumulating chamber 33 Pilot port 40 Stroke switching pilot hole 41 Fluid discharge valve 42 Check valve 43 Pressure control valve 44 Pilot operated check valve 45 Variable throttle valve

Claims (3)

A striking piston having a striking pressure receiving surface and a return pressure receiving surface is fitted in the cylinder so as to be able to reciprocate. A high pressure is always applied to the return pressure receiving surface, and a high pressure and a low pressure are alternately switched on the striking pressure receiving surface. A hydraulic pressure striking device configured to reciprocate the piston, and the stroke of the piston can be switched between a short stroke and a long stroke by a stroke switching valve,
A stroke switching pilot hole is provided in the reversing chamber to take out the high fluid pressure generated in the reversing chamber when the piston is struck.
The fluid discharge valve that operates by receiving the fluid pressure from the stroke switching pilot hole causes the fluid to be accumulated in the pressure accumulating chamber provided in the stroke switching valve, and then switches from the short stroke to the long stroke by switching the stroke switching valve. A fluid pressure type striking device. The hydraulic striking device according to claim 1,
A fluid pressure striking device characterized in that a movable stroke of a spool in a fluid discharge valve can be adjusted. The hydraulic striking device according to claim 1 or 2,
A fluid pressure striking device characterized in that a flow rate for accumulating fluid in a pressure accumulating chamber by a fluid discharge valve can be adjusted by a variable throttle.

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