JPH0683968B2 - Hydraulic breaker - Google Patents

Description

The present invention relates to a hydraulic breaker having a striking piston.

[Conventional technology]

Conventionally, in hydraulic breakers, to prevent pressure pulsation,
It was common to provide an accumulator in the breaker body or piping.

However, the accumulator cannot avoid the occurrence of problems such as damage to the rubber bag, resulting in an increase in running cost of the breaker.

In recent years, some small and medium-sized hydraulic breakers have been able to significantly reduce pressure pulsations, and those in which provision of an accumulator has been omitted have appeared. In particular, the one in which the accumulator for the low-pressure passage is omitted has become the mainstream in recent years.

However, since it is inevitable that the striking piston rebounds and rises rapidly after striking the chisel, the first pressure chamber that acts on the part where the pressure receiving area of the striking piston that is constantly receiving high pressure is small is suddenly depressurized. In addition, it is inevitable that the second pressure chamber, which acts on a large pressure receiving area of the striking piston that is alternately switched between the high pressure and the low pressure by being switched by the control valve, suddenly becomes a pressurized state.

Conventionally, the pressure oil in the second pressure chamber, which rapidly rises in pressure, is discharged to the return circuit as it is. Therefore, consideration must be given to piping such as a hose so as to withstand the pressure pulsation after hitting the chisel. When a high-pressure accumulator is provided in the pipe connected to the first pressure chamber where the pressure drops sharply, the pressure change in the first pressure chamber is rapid, which causes a problem in the accumulator. Further, the rapid pressure change in the first pressure chamber has been a factor in the occurrence of pressure pulsation.

[Problems to be Solved by the Invention]

The present invention solves the above-mentioned conventional problems and provides a hydraulic breaker capable of improving the crushing capacity of a breaker without causing pressure fluctuations in two pressure chambers even when the impact piston rebounds and rises. It is an issue.

[Means for Solving the Problems]

The present invention solves the above problems by applying a pressure to a second pressure chamber having a large pressure receiving area of a striking piston of a hydraulic breaker and a first pressure receiving surface having a small pressure receiving area. The pressure chamber is connected via a booster valve, and the pressure oil in the second pressure chamber is discharged to the booster valve in response to the repulsion of the striking piston after striking to absorb the pressure rise in the second pressure chamber. This is achieved by a hydraulic breaker characterized in that pressure oil is supplied to the first pressure chamber by a booster valve to compensate for the pressure drop in the first pressure chamber.

[Action]

According to the present invention, a high pressure is constantly applied to the first pressure chamber to give the habit of moving the striking piston to a position away from the chisel,
A high pressure source and a low pressure source are alternately connected to the second pressure chamber by a control valve, and when the high pressure is applied, the impact piston is impacted toward the chisel due to the difference in pressure receiving area, and when the low pressure is applied, the impact piston is moved back to the chisel. In a hydraulic breaker that repeats impact, pressure oil in the second pressure chamber, which is going to be pressure-increased by a repulsive impact piston after impact, is discharged to a booster valve to absorb the pressure and avoid an increase in pressure in the second pressure chamber. . At the same time, the pressure oil that has been boosted in the booster valve by the pressure oil from the second pressure chamber is supplied to the first pressure chamber, and a sudden pressure drop in the first pressure chamber is eliminated.

〔Example〕

 The details of the present invention will be described based on the embodiments shown in the drawings.

In FIG. 1, the impact piston 2 is attached to the hydraulic breaker body 1.
Is reciprocally slidably guided. The striking piston 2 strikes the chisel 3 when the striking piston 2 moves downward in the drawing.

The striking piston 2 has two pressure receiving surfaces having different areas: a first pressure receiving surface A1 having a small pressure receiving area and a second pressure receiving surface A2 having a large pressure receiving area.

The hydraulic breaker main body 1 includes a first pressure chamber 4 that stores pressure oil that exerts pressure on the first pressure receiving surface A2, and a second pressure chamber 5 that stores pressure oil that exerts pressure on the second pressure receiving surface A2. It is formed. A high pressure source 6 is connected to the first pressure chamber 4 by a pipe line 7, and a control valve 9 is connected to the second pressure chamber 5 by a pipe line 8.

The control valve 9 is formed so that the high pressure source 6 and the low pressure source 10 can be alternately switched and connected to the second pressure chamber 5. In the example of FIG. 1, the control valve 9 has a valve body 11 and a control piston 12 slidably guided by the valve body 11. The control piston 12 has a through hole 13 in the axial direction inside, and a first step portion 14, a second step portion 15, and a third step portion 16 are formed on the outer peripheral surface as three pressure receiving surfaces having different pressure receiving areas. It The valve body 11 has a first step 14 for applying pressure to the first step portion 14.
A chamber 17, a second chamber 18 that exerts pressure on the second step portion 15, and a third chamber
Control chamber and third chamber 19 that applies pressure to the step
A fourth chamber 20 formed to face one end of 12 and connected to the second pressure chamber 5 by the conduit 8; and a control piston 12
And a fifth chamber 21 formed facing the opposite end of the sixth chamber, and a sixth chamber 21 that can communicate with the fifth chamber 21 according to the movement of the control piston 12.
A chamber 22 is formed.

The hydraulic breaker body 1 is connected to the control valve 9 and has a first groove 23 for controlling a moving stroke of the striking piston 2, and a second groove 23 at a predetermined interval with respect to the first groove 23.
24 is formed, and the first groove 23 and the second groove 24 can be communicated with each other by the small-diameter intermediate portion 25 formed in the striking piston 2 in accordance with the movement of the striking piston 2.

A booster valve 26 is provided between the first pressure chamber 4 and the second pressure chamber 5.
Connected via. In the example of FIG. 1, the through hole 13 in the control piston 12 of the pipe 8 and the control valve 9
The second pressure chamber 5 and the booster valve 26 are connected to each other through the pipe line 27, and the first pressure chamber 4 and the booster valve 26 are connected to each other through the pipe line 28.
Is directly connected by.

The booster valve 26 has a main body 29 and a valve piston 30 slidably guided by the main body 29. In the main body 29, a first valve chamber 31 connected to the second pressure chamber 5 by a pipe 27, a second valve chamber 32 separated from the first valve chamber 31 by a valve piston 30, and a first pressure chamber 4 are provided. The valve piston 30 is connected by a pipe 28 and is isolated from the first valve chamber 31 and the second valve chamber 32.
The piston chamber 33 in which the small-diameter piston portion 30a slides is formed, and the low-pressure chamber 35 connected to the low-pressure source 10 by the pipe line 34 is formed in the piston chamber 33. Low pressure chamber 35 is a valve piston
Depending on the movement of 30, the small diameter portion 30a can switch between communication with and disconnection from the piston chamber 33.

Explaining the operation of the hydraulic breaker, a high pressure is constantly acting on the first pressure chamber 4, and in the state of FIG.
Low pressure is acting on. That is, the second chamber 18 of the control valve 9 is connected to the low pressure source 10 via the conduit 37 via the conduit 34.
Lateral hole connected to the control piston 12
Since 42 communicates with the second chamber 18, the second pressure chamber 5 is
The low pressure in the second chamber 18 acts through the chamber 20, the through hole 13, and the lateral hole 42. At this time, a low pressure acts on the first valve chamber 31 of the booster valve 26 through the through hole 13 and the conduit 27, and the second valve chamber 31
At 32, a second groove 24 connected to the second chamber 18 of the control valve 9 by a conduit 38 communicates with the first groove 23 by an intermediate chamber 25, and the first groove 23 becomes a second valve chamber by a conduit 40. Since it is connected to 32, low pressure is acting. In addition, the same low pressure acts on the other pressure receiving surfaces of the valve piston 30, and the spring 49 of appropriate force acts on the end surface of the valve piston 30 on the piston chamber 33 side. Held in position.

The first chamber 17 of the control valve 9 is connected to the pipe 7 by the pipe 36.
And the third chamber 19 is connected to the first chamber 23 of the hydraulic breaker main body 1 by the pipe 39, so that the low pressure source is connected.
It communicates with 10 and it is a control piston by the pressure difference.
12 is held in the position of FIG.

As described above, since the first pressure chamber 4 receives the high pressure and the second pressure chamber 5 receives the low pressure, the striking piston 2 moves upward in the drawing.

When the striking piston 2 moves back from the stroke end position in the state shown in FIG. 1 over the stroke S, the first pressure receiving surface A1
Is located in the first groove 23, the first groove 23 and the first pressure chamber 4 are in communication with each other, and the first groove 23 and the control valve 9
The third chamber 19 and the second valve chamber 32 of the booster valve 26 are changed to a state in which high pressure acts. Due to this pressure change,
The control piston 12 of the control valve 9 begins to move upward in the figure because the first step portion 14 and the third step portion 16 are both subjected to high pressure, but there is a difference in pressure receiving area. Booster valve 26 does not change.

Due to the movement of the control piston 12, the sixth chamber 22 which is always connected to the high pressure source 6 through the conduit 41 communicates with the fifth chamber 21, and further communicates with the through hole 13 inside the control piston 12, whereby the hydraulic breaker body 1 High pressure acts on the second chamber 5 of
At the same time, the high pressure also acts on the first valve chamber 31 of the booster valve 26. Due to this pressure change, the striking piston 2 starts striking downward in the figure due to the difference in pressure receiving area between the first pressure receiving surface A1 and the second pressure receiving surface A2. The booster valve 26 maintains the current status due to the difference in pressure receiving area.

Immediately before the striking piston 2 strikes the chisel 3, the intermediate portion 25
When the first groove 23 and the second groove 24 communicate with each other, the second chamber 15 and the third chamber 19 of the control valve 9 communicate with each other, and the third chamber 19
Changes to low pressure. Due to this pressure change, the control piston 12 moves downward in the figure toward the initial state shown in the figure, and in the booster valve 26, the second valve chamber 32 becomes a low pressure, and the valve piston 30 resists the action of the spring 49. To the left of.

In the meantime, the striking piston 2 strikes the chisel 3 and repulsively moves back to the upper side of the drawing, rapidly increasing the pressure in the second chamber 5 and rapidly reducing the pressure in the first chamber 4. However, the second pressure chamber 5 is connected to the first valve chamber 31 of the booster valve 26, and the second pressure chamber 5 is connected to the second valve chamber 31 in response to the repulsive return movement of the striking piston.
The pressure oil in the pressure chamber 5 moves to the booster valve 26, and the valve piston 30 further moves due to this pressure oil. The piston chamber 33 and the low pressure chamber 35 of the booster valve 26 are the small diameter piston 30a.
Immediately before being shut off by the valve piston 30, the end portion of the valve piston 30 on the side of the first valve chamber 31 separates from the cushion chamber 43 of the main body 29, and the force pushing the valve piston 30 further increases, and the valve piston 30 continues to move, and the low pressure chamber The pressure oil in the piston chamber 33, which is cut off from 35, is compressed, and the pressurized oil is supplied to the first pressure chamber 4 through the check valve 44. As a result, the pressure oil is supplied to the first pressure chamber 4 whose pressure is about to decrease due to the repulsion of the striking piston 2 by the booster valve 26 and the pressure decrease is prevented.

The horizontal hole 42 is moved to the second chamber 18 by the movement of the control piston 12.
The second pressure chamber 5 is connected to the circuit to the low pressure source 10, and the pressure of the oil pressurized in the second pressure chamber 5 gradually decreases. At that time, the pressure in the first valve chamber 31 also gradually decreases,
Since the pressure receiving area difference between both ends of the valve piston 30 is sufficiently large, the movement of the valve piston 30 continues.

The booster valve 26 absorbs the oil in the second pressure chamber 5 that is pressurized when the striking piston is repulsed, and at that time, the pressure oil boosted by the valve piston 30 is supplied to the first pressure chamber 4 and the first pressure chamber 4 is supplied. And the occurrence of pressure pulsation in the second pressure chamber 5 is prevented.

The operation after the returning movement of the striking piston 2 is similar to the above,
Although the striking piston 2 moves beyond the stroke S,
By that time, the valve piston 30 is returned to the initial state shown in the figure by the spring 49, and thereafter the operation is repeated in the same manner as above.

The booster valve can be modified as shown in FIG. 2 with respect to the example of FIG. Booster valve 2 shown in FIG.
6'is different from the booster valve 26 shown in FIG. 1 in that the narrow hole 45 'of the valve piston 30' is not a through hole but is opened to the peripheral surface of the valve piston 30 'by a lateral hole 46, and the valve piston 30' is opened. In the initial state shown in the drawing, the lateral hole 46 can communicate with each other, the third valve chamber 47 connected to the low pressure source 10 is formed, and the low pressure chamber 35 in the example of FIG.
It has been transformed into a high pressure chamber 35 'connected to the
A check valve with fixed throttle 44 'instead of the
The 49 is no longer needed and is modified, and the other parts are the same. The same parts are designated by the same reference numerals and the description thereof will be omitted.
Since high pressure oil is constantly supplied to the piston chamber 33, the first
High-pressure oil is more reliably supplied to the pressure chamber.

〔effect〕

According to the present invention, it is possible to prevent a rapid change in pressure when the striking piston is repulsed by a simple structure in which the first pressure chamber and the second pressure chamber of the hydraulic breaker are connected by a booster valve.

The booster valve operates as a chamber that absorbs pressure oil in the second pressure chamber and as a piston pump that supplies pressure oil to the first pressure chamber. Therefore, the pressure increase in the second pressure chamber can be suppressed, the pressure decrease in the first pressure chamber can be prevented, the rising speed of the striking piston can be increased, and the number of times of striking can be increased. Further, the pressure of the discharged oil was sufficiently reduced, and it became possible to prevent pulsation and increase in oil temperature.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic breaker according to the present invention, and FIG. 2 is a sectional view of a modified booster valve. 2 ... Impact piston, 3 ... Chisel 4 ... 1st pressure chamber, 5 ... 2nd pressure chamber 6 ... High pressure source 9 ... Control valve 10 ... Low pressure source, 26 ... Booster valve 30 ... Valve piston

Claims (1)

[Claims] 1. A striking piston for striking a chisel having two pressure receiving surfaces having different areas, a first pressure chamber for exerting hydraulic pressure on a first pressure receiving surface having a small area of the striking piston, and a large area. A second pressure chamber that applies hydraulic pressure to the second pressure receiving surface,
A hydraulic breaker in which a high pressure circuit is always connected to the first pressure chamber, and a high pressure circuit and a low pressure circuit are alternately and switchably connected to the second pressure chamber via a control valve, wherein the first pressure chamber and the first pressure chamber are connected to each other. The two pressure chambers are connected via a booster valve, and the pressure oil in the second pressure chamber is discharged to the booster valve in response to the repulsion of the striking piston after the striking piston. A hydraulic breaker characterized by supplying to a pressure chamber.