JP2000052276A - Stroke switchover device for impact mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust impact force in more detail by selecting the stroke of a piston in multi-stages. SOLUTION: In an impact mechanism wherein a front chamber high pressure port 26 is provided, which communicates the front chamber 3 of a cylinder 2 with a high pressure circuit 5, and a rear chamber port 29 is provided, which communicates the rear chamber 4 with a control valve 7, and let a piston 1 be moved back and forth by letting the hydraulic pressure of the rear chamber 4 be switched over by the control valve 7, a valve control port 24 communicated with the pilot port of the control valve 7, and an oil exhaust port 25 communicated with a low pressure circuit 8, are interposed between the front chamber high pressure port 26 and the rear chamber port 29, and a communication groove 30 communicating the valve control port 24 with the oil exhaust port 25 when a piston 1 is advanced, is provided for the outer circumference of the large diameter part 1B of the piston 1, and a long stroke port 28 to be opened to the front chamber 3 side when the piston 1 is moved backward, a middle stroke port 23, and a short stroke port 27 are disposed in front of the valve control port 24, and a stroke adjuster 10 is provided, which switches over the respective stroke ports 28, 23 and 27 in such a way as to be communicated with the pilot port of the control valve 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stroke switching device for a striking mechanism used in a hydraulic rock drill, a hydraulic breaker, or the like.

[0002]

2. Description of the Related Art Conventionally, a hydraulic rock drill, a hydraulic breaker and the like use a striking mechanism as shown in FIG.

Here, a piston 1 is slidably fitted in the center of the cylinder 2 of the striking mechanism D so as to be able to reciprocate in the front-rear direction, and a rod 22 is inserted in front of the piston 1 (upper left side in FIG. 9). ing.

In this striking mechanism D, the piston 1 has a large-diameter portion 1B in the center, a small-diameter portion 1A in front of the large-diameter portion 1B, and a small-diameter portion 1A in the rear.
The front chamber 3 and the rear chamber 4 are formed by this difference in diameter. The rear small-diameter portion 1C has a smaller diameter than the front small-diameter portion 1A, so that the piston 1 has a larger pressure receiving area on the rear chamber 4 side than on the front chamber 3 side.

[0005] The cylinder 2 is provided with a front chamber high pressure port 26 for communicating the front chamber 3 with the high pressure circuit 5 and a rear chamber port 29 for communicating the rear chamber 4 with the control valve 7. Control valve 7
Is a 2-position pilot operated switching valve, which connects the rear chamber 4 to the tank 9 via the low pressure circuit 8 in the normal position, and connects the rear chamber 4 to the pump 6 via the high pressure circuit 5 when switched to the operating position. Communicate.

A pilot port of the control valve 7 and a valve control circuit 31 are provided between the front chamber high pressure port 26 and the rear chamber port 29.
And a valve control port 24 communicating with the
An oil discharge port 25 communicating with the low pressure circuit 8 is provided behind the valve control port 24. Large diameter part 1 of piston 1
On the outer periphery of B, a communication groove 30 is provided for communicating the valve control port 24 and the oil discharge port 25 just before the striking position when the piston 1 advances.

A short stroke port 27 and a long stroke port 2 are provided in front of the valve control port 24.
8 are arranged at a predetermined distance back and forth, and a short stroke port 27 and a long stroke port 28 are arranged.
Means the valve control circuit 3 via the stroke adjuster 20
1 is connected.

The stroke adjuster 20 is a two-position pilot operation switching valve. A stroke control circuit 32 is connected to a pilot port of the stroke adjuster 20, and a long stroke port 28 is connected to the valve control circuit 31 at a normal position.
The short stroke port 27 is connected to the pilot port of the control valve 7 via the valve control circuit 31 when the operating position is switched to the pilot port of the control valve 7 via the control valve 7.

In this striking mechanism, the valve control port 24 is closed by the large diameter portion 1B of the piston 1 as shown in FIG.
When the long stroke port 28 and the pilot port of the control valve 7 communicate with each other, the control valve 7 is switched to the operating position, and the rear chamber 4 communicates with the pump 6 via the high-pressure circuit 5. The high pressure is applied to both the chamber 3 and the chamber 3. Piston 1
Since the pressure receiving area on the rear chamber 4 side is larger than the pressure receiving area on the front chamber 3 side, the piston 1 moves forward.

When the piston 1 moves forward, the long stroke port 28 and the short stroke port 27 are closed by the large diameter portion 1B of the piston 1, and the valve control port 24 and the drain port 25 are connected to the communication groove 30 shortly before the impact position. , The pressure in the valve control circuit 31 becomes low and the control valve 7
Is in the normal position, and the rear chamber 4 is communicated with the tank 9 via the low-pressure circuit 8.

The piston 1 strikes the rod 22, stops moving forward, and starts retreating. When the piston 1 retreats and the large diameter portion 1B of the piston 1 closes the valve control port 24 and opens the long stroke port 28, the long stroke port 28 and the pilot port of the control valve 7 communicate with each other.
Is switched to the operating position, and the pressure in the rear chamber 4 becomes high. The piston 1 stops retreating and enters the forward travel again.

When the stroke adjuster 20 is switched by the control pressure of the stroke control circuit 32 and the short stroke port 27 is communicated with the pilot port of the control valve 7 via the valve control circuit 31, the large-diameter portion When 1B closes the valve control port 24 and opens the short stroke port 27, the short stroke port 27 communicates with the pilot port of the control valve 7, the control valve 7 is switched to the operating position, and the rear chamber 4 becomes high pressure. So
The piston 1 stops retreating and enters the forward travel again. Since the timing of entering the forward travel is earlier, the stroke of the piston 1 is shorter.

Accordingly, in the striking mechanism D, the stroke adjuster 20 is switched to select either the long stroke or short stroke of the piston 1 in accordance with the properties of the object to be crushed or the content of the work, so that the striking force is changed. Can be adjusted.

[0014]

In this striking mechanism, the stroke of the piston can be selected from two stages, long and short, so that the striking force can be adjusted in two stages, large and small.

However, since the properties of a crushing object such as a hydraulic rock drill and a hydraulic breaker vary greatly, it is desired that the impact mechanism adjusts the impact force more finely. An object of the present invention is to solve such a problem in a striking mechanism, and an object of the present invention is to provide a stroke switching device of a striking mechanism capable of selecting a stroke of a piston in more steps and adjusting a striking force more finely. And

[0016]

According to the stroke switching device of the striking mechanism of the present invention, a front chamber and a rear chamber are formed by slidingly fitting a piston having a large-diameter portion at the center and a small-diameter portion in front of and behind the cylinder. A front chamber high pressure port for communicating the front chamber with the high pressure circuit, and a rear chamber port for communicating the rear chamber with the control valve are provided, and the control valve alternately switches the rear chamber between the high pressure circuit and the low pressure circuit to communicate therewith. In a striking mechanism for reciprocating the piston back and forth, a valve control port communicating with a pilot port of a control valve via a valve control circuit is provided between the front chamber high pressure port and the rear chamber port of the cylinder. An oil drain port communicating with the low pressure circuit is provided at the rear, and a communication groove for communicating the valve control port and the oil drain port before the striking position when the piston advances is provided on the outer periphery of the large diameter portion of the piston, Valve control port A long-stroke port, a middle-stroke port, and a short-stroke port, which are located at a predetermined distance from each other, open to the anterior chamber when the piston retreats. And a stroke adjuster that switches one of the two to communicate with the pilot port of the control valve.

When the long stroke port is communicated with the pilot port of the control valve by the stroke adjuster, the control valve is switched to the operating position when the long stroke port is opened during the retraction stroke of the piston, and the pressure in the rear chamber becomes high. However, it stops retreating and enters into the forward progress.
Since the timing of entering the forward travel is delayed, the stroke of the piston is lengthened, and the impact force is increased.

When the short stroke port is connected to the pilot port of the control valve by the stroke adjuster,
In the retraction stroke of the piston, when the short stroke port is opened, the control valve is switched to the operating position, the pressure in the rear chamber becomes high, and the piston stops retreating and enters the forward stroke. Since the timing of entering the forward travel is earlier, the stroke of the piston is shorter, and the impact force is smaller.

When the middle stroke port communicates with the pilot port of the control valve by the stroke adjuster, the stroke has an intermediate length, and the striking force also has an intermediate magnitude.

Therefore, by switching one of the long stroke port, the middle stroke port and the short stroke port to communicate with the pilot port of the control valve by the stroke adjuster, the stroke of the piston can be set to three stages of long, middle and short. The impact force can be more finely adjusted according to the properties of the crushing object and the content of the work.

When the stroke adjuster is a pilot operation switching valve, stroke switching can be remotely controlled, and the rotation pressure of the rotation mechanism and the feed pressure of the feed mechanism can be automatically controlled as control pressure.

A rotary valve can be used as the stroke adjuster.

[0023]

FIG. 1 is a structural view of a striking mechanism showing an embodiment of the present invention, FIG. 2 is a structural view of a stroke adjuster, and FIGS. 3 and 4 are explanatory views of the operation of the stroke adjuster.

Here, the basic structure of the striking mechanism D is the same as that of the prior art, and the piston 1 is fitted on the center of the cylinder 2 so as to be able to reciprocate in the front-rear direction. A rod 22 is inserted in the upper left part of FIG. 1).

The piston 1 has a large-diameter portion 1B in the center, a small-diameter portion 1A in front of the large-diameter portion 1B, and a small-diameter portion 1C in the rear. The difference in the diameters forms a front chamber 3 and a rear chamber 4. The rear small-diameter portion 1C has a smaller diameter than the front small-diameter portion 1A, so that the piston 1 has a larger pressure receiving area on the rear chamber 4 side than on the front chamber 3 side.

The cylinder 2 is provided with a front chamber high pressure port 26 for communicating the front chamber 3 with the high pressure circuit 5 and a rear chamber port 29 for communicating the rear chamber 4 with the control valve 7. Control valve 7
Is a 2-position pilot operated switching valve, which connects the rear chamber 4 to the tank 9 via the low pressure circuit 8 in the normal position, and connects the rear chamber 4 to the pump 6 via the high pressure circuit 5 when switched to the operating position. Communicate.

A pilot port of the control valve 7 and a valve control circuit 31 are provided between the front chamber high pressure port 26 and the rear chamber port 29.
And a valve control port 24 communicating with the
An oil discharge port 25 communicating with the low pressure circuit 8 is provided behind the valve control port 24. Large diameter part 1 of piston 1
On the outer periphery of B, a communication groove 30 is provided for communicating the valve control port 24 and the oil discharge port 25 just before the striking position when the piston 1 advances.

A short stroke port 27 and a middle stroke port 2 are provided in front of the valve control port 24.
3 and the long stroke port 28 are arranged at a predetermined distance in the front and rear direction, and the short stroke port 27
The middle stroke port 23 and the long stroke port 28 are connected to the valve control circuit 31 via the stroke adjuster 10.

The stroke adjuster 10 is a pilot operation switching valve, and includes a spool 12 in a valve box 11 as shown in FIG. A stroke control oil chamber 13 is formed on the right side of the spool 12 and a return oil chamber 14 is formed on the left side of the spool 12, and a stroke control circuit 32 is connected to the stroke control oil chamber 13 via a pilot port. A return spring 15 is mounted in the return oil chamber 14.

The return oil chamber 14 is always at a constant pressure, and the stroke control circuit 32
When no control pressure is applied to the spool 12, the spool 12
Is a long stroke selecting oil passage L which moves rightward and is connected to the long stroke port 28 as shown in FIG.
Is communicated with the valve control circuit 31.

When a control pressure is applied from the stroke control circuit 32 to the stroke control oil chamber 13, the spool 12 moves to the left as shown in FIG.
Is connected to the valve control circuit 31.

When the control pressure applied from the stroke control circuit 32 to the stroke control oil chamber 13 becomes high, the spool 12 compresses the return spring 15 and moves further to the left as shown in FIG.
Is connected to the valve control circuit 31.

Accordingly, the stroke adjuster 10 allows the long stroke port 28 to communicate with the pilot port of the control valve 7 via the valve control circuit 31 in the normal position, and when the control pressure of the stroke control circuit 32 is low, the middle stroke port 23 is connected to the pilot port of the control valve 7 via the valve control circuit 31. When the control pressure of the stroke control circuit 32 is high, the short stroke port 27 is connected to the pilot port of the control valve 7 via the valve control circuit 31. It is switched to communicate.

In this striking mechanism, as shown in FIG. 1, the valve control port 24 is closed by the large diameter portion 1B of the piston 1.
When the long stroke port 28 and the pilot port of the control valve 7 communicate with each other, the control valve 7 is switched to the operating position, and the rear chamber 4 communicates with the pump 6 via the high-pressure circuit 5. The high pressure is applied to both the chamber 3 and the chamber 3. Piston 1
Since the pressure receiving area on the rear chamber 4 side is larger than the pressure receiving area on the front chamber 3 side, the piston 1 moves forward.

When the piston 1 moves forward, the long stroke port 28, the middle stroke port 23, and the short stroke port 27 are sequentially closed by the large diameter portion 1B of the piston 1, and the valve control port 24 and the drain port are shortly before the striking position. 25 communicates with the tank 9 through the communication groove 30, so that the valve control circuit 31 is at low pressure, the control valve 7 is in the normal position, and the rear chamber 4 is communicated with the tank 9 via the low pressure circuit 8.

The piston 1 hits the rod 22, stops moving forward, and starts retreating. When the piston 1 retreats and the large diameter portion 1B of the piston 1 closes the valve control port 24 and opens the long stroke port 28, the long stroke port 28 and the pilot port of the control valve 7 communicate with each other.
Is switched to the operating position, and the pressure in the rear chamber 4 becomes high. The piston 1 stops retreating and enters the forward travel again. At this time, since the stroke of the piston 1 becomes long, the striking force is also large.

When the stroke adjuster 10 is switched by increasing the control pressure of the stroke control circuit 32 to make the short stroke port 27 communicate with the pilot port of the control valve 7 via the valve control circuit 31, When the large diameter portion 1B closes the valve control port 24 and opens the short stroke port 27, the short stroke port 27 communicates with the pilot port of the control valve 7, the control valve 7 is switched to the operating position, and the rear chamber 4 is closed. Since the pressure becomes high, the piston 1 stops retreating and enters the forward movement again. Since the timing of entering the forward travel is earlier, the stroke of the piston 1 is shortened, and the impact force is reduced.

When the stroke adjuster 10 is switched by reducing the control pressure of the stroke control circuit 32 to make the middle stroke port 23 communicate with the pilot port of the control valve 7 via the valve control circuit 31, The large diameter portion 1B closes the valve control port 24, and the middle stroke port 2 follows the short stroke port 27.
3 is opened, the middle stroke port 23 and the pilot port of the control valve 7 communicate with each other, the control valve 7 is switched to the operating position, and the pressure in the rear chamber 4 becomes high.
Stops retreating and starts again. Since the stroke has an intermediate length, the striking force also has an intermediate magnitude.

Accordingly, with the stroke adjuster 10, the long stroke port 28, the middle stroke port 2
3. By switching any one of the short stroke ports 27 to communicate with the pilot port of the control valve 7, the stroke of the piston 1 can be selectively switched between three stages, long, middle, and short. The hitting force can be adjusted more finely according to the content of.

The stroke adjuster 10 can remotely control the switching of the stroke, and can also automatically control the rotation pressure of the rotation mechanism and the feed pressure of the feed mechanism as the control pressure.

As the stroke adjuster 10, a rotary valve 50 as shown in FIG. 5 can be used. The rotary valve 50 includes a cylindrical spool 52 that rotates in a valve box (not shown). The spool 52 has a long stroke selection oil hole 53A, 53B penetrating the spool 52 in a cross shape, a middle stroke selection oil hole 54 penetrating the spool 52 linearly in the diameter direction, and an outer peripheral surface of the spool 52. And a short stroke selecting oil hole 55 drilled in the radial direction from the center to the center is provided at a predetermined distance in the longitudinal direction.

The direction of the middle stroke selection oil hole 54 is one of the cross-shaped long stroke selection oil holes 53A.
And the direction of the short stroke selection oil hole 55 is parallel to the other long stroke selection oil hole 53B. In addition, a communication oil hole 56 that passes through the center of the spool 52 and connects the long stroke selection oil holes 53A and 53B, the middle stroke selection oil hole 54, and the short stroke selection oil hole 55 is provided.

The spool 52 has a ratchet 57 and a pinion 58 at one end, and the pinion 58 meshes with a rack 60 of an adjuster rod 59. The adjuster rod 59 is configured to move forward when the control signal Si is turned on, and to be retracted by the spring 61 when the control signal Si is turned off. Since the spool 52 is provided with the ratchet 57, when the adjuster rod 59 moves forward, rotation in one direction is given via the pinion 58, but when the adjuster rod 59 moves backward, it does not rotate.

When the spool 52 is at the position shown in FIG. 6, the short stroke port 27 communicates with the valve control circuit 31 via the short stroke selecting oil hole 55, the communication oil hole 56, and the long stroke selecting oil hole 53B. And
The stroke of the piston 1 is shortened.

When the spool 52 rotates 90 degrees to the position shown in FIG. 7, the middle stroke port 23 is connected to the valve control circuit via the middle stroke selecting oil hole 54, the communication oil hole 56, and the long stroke selecting oil hole 53A. 31 and
The stroke of the piston 1 has an intermediate length.

When the spool 52 is further rotated by 90 degrees to the position shown in FIG. 8, the long stroke port 28 communicates with the valve control circuit 31 through the long stroke selecting oil hole 53B, and the stroke of the piston 1 becomes longer. .

From here, when the spool 52 rotates 90 degrees, the stroke of the piston 1 becomes an intermediate length. When the spool 52 rotates further 90 degrees, the state returns to the state shown in FIG. 6, and thereafter, the above cycle is repeated.

As described above, by sending the control signal Si to the adjuster rod 59 and switching the position of the spool 52, the length of the stroke can be selected in accordance with the properties of the object to be crushed and the contents of work. (If there are other effects unique to rotary type, please add)

[0049]

As described above, in the stroke switching device of the striking mechanism of the present invention, the stroke of the piston can be selectively switched in more steps, and the striking force can be changed according to the properties of the object to be crushed and the contents of the work. It can be adjusted more finely.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a striking mechanism according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a stroke adjuster.

FIG. 3 is an explanatory diagram of an operation of a stroke adjuster.

FIG. 4 is an explanatory diagram of an operation of a stroke adjuster.

FIG. 5 is an explanatory diagram of a configuration of a rotary valve that is a stroke adjuster.

FIG. 6 is an explanatory diagram of the operation of the rotary valve.

FIG. 7 is an explanatory diagram of the operation of the rotary valve.

FIG. 8 is an explanatory diagram of the operation of the rotary valve.

FIG. 9 is a configuration diagram of a conventional impact mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston 1A, 1C Small diameter part 1B Large diameter part 2 Cylinder 3 Front chamber 4 Rear chamber 5 High pressure circuit 7 Control valve 8 Low pressure circuit 10 Stroke adjuster 11 Valve box 12 Spool 13 Stroke control oil chamber 14 Return oil chamber 15 Return spring 22 Rod 23 Middle stroke port 24 Valve control port 25 Drainage port 26 Front chamber high pressure port 27 Short stroke port 28 Long stroke port 29 Rear chamber port 30 Communication groove 31 Valve control circuit 32 Stroke control circuit 50 Rotary valve 52 Spool 53A, 53B Long stroke Selection oil hole 54 Middle stroke selection oil hole 55 Short stroke selection oil hole 56 Communication oil hole 57 Ratchet 58 Pinion 59 Adjuster rod 60 Rack 61 Spring L Long stroke択用 oil passage M middle stroke selection for oil passage S short stroke selection for the oil passage

Claims (3)

[Claims] 1. A front chamber high pressure port for slidingly fitting a piston having a large diameter portion at the center and a small diameter portion at the front and rear thereof in a cylinder to form a front chamber and a rear chamber, and connecting the front chamber to a high pressure circuit. A rear chamber port for communicating the rear chamber with the control valve, wherein the control valve alternately communicates the rear chamber with a high-pressure circuit and a low-pressure circuit to cause the piston to reciprocate; Between the chamber high pressure port and the rear chamber port,
A valve control port that communicates with the pilot port of the control valve via a valve control circuit is provided, and an oil drain port that communicates with the low-pressure circuit is provided behind the valve control port, and a piston is provided on the outer periphery of the large diameter portion of the piston. A communication groove for communicating the valve control port and the oil drain port is provided before the impact position when the vehicle advances, and a long stroke port, a middle stroke port, which opens to the front chamber side when the piston retreats, is provided in front of the valve control port. And a short stroke port arranged at a predetermined distance from each other, and a stroke adjuster for switching one of the long stroke port, the middle stroke port, and the short stroke port to communicate with the pilot port of the control valve is provided. Stroke switching device for impact mechanism. 2. The stroke switching device according to claim 1, wherein the stroke adjuster is a pilot operation switching valve. 3. The stroke switching device according to claim 1, wherein the stroke adjuster is a rotary valve.