JPH03184777A - Hydraulic breaker - Google Patents

Abstract

PURPOSE:To keep off any a sudden change of pressure at the resiliency of a stroke piston by connecting an interval between a first pressure chamber and a second pressure chamber of a hydraulic breaker with a booster valve. CONSTITUTION:Pressure oil in a second pressure chamber 5 tries to boost its pressure by dint of a stroke piston 2 resiling after the stroke is discharged to a booster valve 26 and its pressure is absorbed so that a pressure rise in the second pressure chamber 5 is avoided. Simultaneously with this, another pressure oil boosted in the booster valve 26 by the pressure oil out of the second pressure chamber 5 of fed to a first pressure chamber 4, thus a sudden pressure drop in this first pressure chamber 4 is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic breaker with a striking piston.

[Prior art]

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

However, the accumulator cannot avoid problems such as damage to the rubber bag, and there is a problem in that the running cost of the breaker increases.

In recent years, it has become possible to considerably reduce pressure pulsation in medium to small-sized hydraulic breakers, and models that omit the provision of an accumulator have appeared.

In particular, those that omit the accumulator in the low-pressure flow path have become mainstream in recent years.

However, it is unavoidable that the striking piston rebounds rapidly after striking the chisel, so the first pressure chamber, which acts on the small pressure-receiving area of the striking piston that is constantly under high pressure, suddenly becomes depressurized. Furthermore, it is inevitable that the second pressure chamber, which acts on a large pressure-receiving area of the striking piston which is alternately subjected to high and low pressures by being switched by the control valve, will be in a state of rapid pressure increase.

Conventionally, the rapidly rising oil pressure in the second pressure chamber was discharged directly to the return circuit, so consideration had to be given to piping such as hoses to withstand the pressure pulsations after the chisel strike. If a high-pressure accumulator is installed in the piping connected to the first pressure chamber where the pressure drops rapidly, the pressure change in the first pressure chamber will be drastic and may cause problems with the accumulator. was. Further, rapid pressure changes in the first pressure chamber were a factor in the occurrence of pressure pulsations.

[Problem to be solved by the invention]

The present invention solves the above conventional problems and provides a hydraulic breaker that can improve the crushing ability of the breaker without causing pressure fluctuations in the two pressure chambers even when the striking piston rebounds upward. That is the issue.

[Means to solve the problem]

The present invention solves the above problems with a second pressure chamber that applies pressure to a second pressure-receiving surface with a large pressure-receiving area of a striking piston of a hydraulic breaker, and a first pressure chamber that applies pressure to a first pressure-receiving surface with 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 rebound movement of the striking piston after impact, absorbing the pressure increase in the second pressure chamber. It is distantly related to the hydraulic breaker, which is characterized by supplying pressure oil to the first pressure chamber by a booster valve to compensate for the pressure drop in the first pressure chamber.

[Effect]

According to the present invention, high pressure always acts on the first pressure chamber, giving a habit of moving the striking piston to a position away from the chisel,
A control valve alternately switches and connects a high pressure source and a low pressure source to the second pressure chamber, and when high pressure is applied, the impact piston is moved toward the chisel due to the difference in pressure receiving area, and when low pressure is applied, the impact piston is moved back against the chisel. In a hydraulic breaker that repeatedly strikes, the pressure oil in the second pressure chamber that attempts to rise in pressure due to the striking piston that rebounds after striking is discharged to the booster valve and absorbs the pressure, thereby avoiding a rise in pressure in the second pressure chamber. . At the same time, pressure oil whose pressure has been increased in the booster valve by pressure oil from the second pressure chamber is supplied to the first pressure chamber, thereby eliminating the sudden pressure drop in the first pressure chamber.

〔Example] The details of the present invention will be explained based on embodiments shown in the drawings.

In FIG. 1, a striking piston 2 is attached to a hydraulic breaker body 1.
is slidably guided so that it can reciprocate. During the downward striking movement of the striking piston 2 in the diagram, the chisel 3 is struck.

The striking piston 2 has two pressure-receiving surfaces having different performance results: 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 body l includes a first pressure chamber 4 that accommodates pressure oil that applies pressure to the first pressure receiving surface A1, and a second pressure chamber 5 that accommodates pressure oil that applies pressure to the second pressure receiving surface A2. It is formed. A high pressure source 6 is connected to the first pressure chamber 4 through a conduit 7, and a control valve 9 is connected to the second pressure chamber 5 through a conduit 8.

The control valve 9 connects the high pressure source 6 and the low pressure source 10 to the second
It is formed so that it can be connected to the pressure chamber 5 alternately. In the example shown in FIG. 1, the control valve 9 includes a valve body 11 and a control piston 12 that is slidably guided by the valve body 11.
and has. The control piston 12 has an axial through hole 13 inside, and has three holes on the outer circumferential surface having different pressure receiving areas.
A first step 14, a second step 15, and a third step 16 are formed as three pressure receiving surfaces. The valve body 11 has a first stage portion 1.
4, a second chamber 18 that applies pressure to the second stage 15, a third chamber 19 that applies pressure to the third stage 15, and one end of the control piston 12. a fourth chamber 20 formed facing the second pressure chamber 5 and connected to the second pressure chamber 5 by the pipe line 8; a fifth chamber 21 formed facing the opposite end of the control piston 12; A sixth chamber 22 that can communicate with each other according to the movement of the control piston 12
is formed.

A first groove 23 and a second groove 24 are formed in the hydraulic breaker body 1 at a predetermined interval with respect to the first groove 23 in order to be connected to the control valve 9 to control the movement stroke of the striking piston 2. The first
The groove 23 and the second groove 24 can communicate with each other.

A booster valve 2 is connected between the first pressure chamber 4 and the second pressure chamber 5.
6. In the example shown in FIG. 1, the second pressure chamber 5 and the booster valve 26 are connected through the pipe line 8 and the through hole 13 in the control piston 12 of the control valve 9 and the pipe line 27, and the first pressure chamber 4 and the booster valve 2
6 is directly connected by a conduit 28.

The booster valve 26 has a body 29 and a valve piston 30 slidingly guided in the body 29.

The main body 29 includes a first valve chamber 31 connected to the second pressure chamber 5 through a conduit 27, a second valve chamber 32 separated from the first valve chamber 31 by a valve piston 30, and a second valve chamber 32 connected to the first pressure chamber 4. A piston chamber 33 is formed, which is connected by a pipe line 28 and isolated from the first valve chamber 31 and the second valve chamber 32, on which the small diameter piston portion 30a of the valve piston 30 slides. A low pressure chamber 35 is formed which is connected by a channel 34 . The low pressure chamber 35 can be switched between communicating and blocking the piston chamber 33 by means of the small diameter portion 30a according to the movement of the valve piston 30.

To explain the operation of the hydraulic breaker, high pressure is always acting on the first pressure chamber 4, and in the state shown in FIG.
low pressure is acting on it. That is, the second chamber 18 of the control valve 9 is connected to the low pressure source 10 by the conduit 37 via the conduit 34, and the horizontal hole 42 formed in the control piston 12 communicates with the second chamber 18. 2
The low pressure of the second chamber 18 acts on the pressure chamber 5 through the fourth chamber 20, the through hole 13, and the side hole 42. At this time, 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 32 is connected to the second chamber 18 of the control valve 9 by a conduit 38. The second groove 24 communicates with the first groove 23 through the intermediate chamber 25, and
Since the groove 23 is connected to the second valve chamber 32 by a line 40, a low pressure is present. In addition, the same low pressure acts on other pressure-receiving surfaces of the valve piston 30, and a spring 49 with an appropriate force acts on the end of the valve piston 30 on the piston chamber 33 side, so that the valve piston 3
0 is held in the position shown.

The first chamber 17 of the control valve 9 is connected by a conduit 36 to the high pressure source 6 via the conduit 7, and the third chamber 19 is connected to the high pressure source 6 via the conduit 7.
9 is connected to the first chamber 23 of the hydraulic breaker main body 1, so that it communicates with the low pressure source 10, and the control piston 12 is held at the position shown in FIG. 1 due to the pressure difference.

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

When the striking piston 2 moves back beyond the stroke S from the stroke end position shown in FIG.
1 is located in the first groove 23, and the first groove 33 and the first pressure chamber 4
The first groove 23, the third chamber 19 of the control valve 9, and the second chamber of the booster valve 26 are in communication with each other.
The valve chamber 32 changes to a state where high pressure is applied. Due to this pressure change, the control piston 12 of the control valve 9 begins to move upward in the figure because both the first stage part 14 and the third stage part 16 are affected by high pressure, but there is a difference in pressure receiving area. . Booster valve 26 makes no change.

As the control piston 12 moves, the sixth chamber 22, which is constantly connected to the high pressure IfI6 through the conduit 41, communicates with the fifth chamber 21, and further communicates with the through hole 13 inside the control piston 12, so that High pressure acts on the second chamber 5, and at the same time, high pressure acts on the first valve chamber 31 of the booster valve 26. Due to this pressure change, the striking piston 2 starts a striking movement downward in the diagram due to the difference in pressure receiving area between the first pressure receiving surface A1 and the second pressure receiving surface A2. In the booster valve 26, the current state is maintained due to the difference in pressure receiving area.

Immediately before the striking piston 2 strikes the chisel 3, the intermediate part 2
5, when the first groove 23 and the second groove 24 communicate with each other, the second chamber 15 and third chamber 19 of the control valve 9 communicate with each other, and the pressure in the third chamber 19 changes to low pressure. This pressure change causes the control piston 12 to return downward in the figure toward the initial state shown in the figure, and in the booster valve 26, the second valve chamber 32 becomes under low pressure, and the valve piston 30 moves against the action of the spring 49. Start moving to the left side.

During this time, the striking piston 2 strikes the chisel 3 and moves back upward in the drawing, rapidly increasing the pressure in the second chamber 5 and rapidly decreasing 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 pressure oil in the second pressure chamber 5 moves to the booster valve 2G in response to the rebound movement of the striking piston. This causes the valve piston 30 to move further. Immediately before the piston chamber 33 and low pressure chamber 35 of the booster valve 26 are shut off by the small diameter piston 30a, the end of the valve piston 30 on the first valve chamber 31 side separates from the cushion chamber 43 of the main body 29, and a force pushing the valve piston 30 is generated. becomes even larger, and the valve piston 30 continues to move, compressing the pressure oil in the piston chamber 33 which is isolated from the low pressure chamber 35, and supplies the pressurized oil 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 drop due to the rebound movement of the striking piston 2 by the booster valve 26, thereby preventing the pressure from dropping.

The movement of the control piston 12 causes the horizontal hole 42 to become the second
When communicating with the chamber 18, the second pressure chamber 5 is connected to a circuit to the low pressure source 10, and the pressure of the pressurized oil in the second pressure chamber 5 gradually decreases. At this time, the pressure in the first valve chamber 31 also gradually decreases, but the movement of the valve piston 30 continues because the difference in pressure receiving area between both ends of the valve piston 30 is sufficiently large.

The booster valve 29 absorbs the oil in the second pressure chamber 5 that increases in pressure when the striking piston rebounds, and at this time the valve piston 3
0 is supplied to the first pressure chamber 4 to prevent pressure pulsations in the first pressure chamber 4 and the second pressure chamber 5 from occurring.

The operation after the return movement of the striking piston 2 is the same as above,
Although the striking piston 2 moves beyond the stroke S,
The valve piston 30 is already returned to the initial state shown in the figure by the spring 49, and the operation is repeated in the same manner as described above.

The booster valve can also be modified from the example shown in FIG. 1 as shown in FIG. Booster valve 2 shown in Figure 2
6' is different from the booster valve 26 shown in FIG. 1 in that the slender 45' of the valve piston 30' is not a through hole, but is opened on the circumferential surface of the valve piston 30' by a horizontal hole 46 in the middle;
When the valve piston 30' is in the initial state shown in the figure,
A third valve chamber 47 is formed in which the side hole 46 can communicate and is connected to the low pressure source 10, and the low pressure chamber 35 of the example of FIG. The modifications are that a fixed throttle stop valve 44' is provided in place of the check valve 44, and that the spring 49 is no longer necessary, and the other parts are the same. Identical parts are given the same reference numerals and explanations will be omitted. Since high pressure oil is constantly supplied to the piston chamber 33, high pressure oil is supplied to the first pressure chamber more reliably.

〔effect〕

According to the present invention, a rapid change in pressure during the rebound movement of the striking piston can be prevented by a simple configuration 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, it is possible to suppress the pressure rise in the second pressure chamber and prevent the pressure drop in the first pressure chamber, thereby increasing the rising speed of the striking piston and making it possible to increase the number of strikes. In addition, the pressure of the discharged oil is sufficiently reduced, making it possible to prevent pulsation and oil temperature rise.

[Brief explanation 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 example of a booster valve. 2... Impact piston 3... Chisel 4... First pressure chamber 5... Second pressure chamber 6... High pressure source 9... Control valve 10... Low pressure source 26... Booster Valve 30...Valve piston Fig. 2

Claims (1)

[Claims] A striking piston that strikes a chisel and has two pressure-receiving surfaces with different areas, a first pressure chamber that applies hydraulic pressure to a first pressure-receiving surface that has a small area, and a first pressure chamber that has a large area. a second pressure chamber that applies hydraulic pressure to a second pressure receiving surface, a high pressure circuit is always connected to the first pressure chamber, and a high pressure circuit and a low pressure circuit are connected to the second pressure chamber via a control valve. In the hydraulic breaker, the first pressure chamber and the second pressure chamber are connected via a booter valve, and the pressure chamber of the second pressure chamber is changed in response to the rebound movement after the impact of the impact piston. A hydraulic breaker, characterized in that the pressure oil is discharged to the booster valve, and the booster valve supplies the pressure oil to the first pressure chamber.