JPH09131671A - Hydraulic breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic breaker which provides high energy efficiency and stable hitting force, does not cause a gas leakage, and has excellent durability. SOLUTION: It is a breaker in which a hammer piston 3 is arranged in a main body on which a tool T is mounted in its lower section and which supplies energy accumulated by an accumulator 2 provided at an upper end of the main body to hydraulic oil to operate the hammer piston 3 and hit the tool T. An oil chamber 50 in which an upper piston 3c of the hammer piston 3 faces the inside thereof is partitioned through a bulkhead 5a below the accumulator 2. An annular oil chamber 51 which is connected to a hydraulic oil inlet passage 6 and a high pressure passage 12 which operates the hammer piston 3 respectively is provided on outer periphery of the bulkhead, and an oil chamber control valve 7 which controls pressure in the oil chamber 50 to a specified scope and replaces hydraulic oil in the oil chamber by a small amount due to fluctuation of pressure in the oil chamber in accordance with ascent and descent stroke of the hammer piston 3 is provided on the outside in the vicinity of the annular oil chamber 51.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hydraulic breaker.

[0002]

2. Description of the Related Art A hydraulic flaker (hydraulic hammering device) is widely used as a crushing means for rocks, bedrock, concrete and the like in construction and civil engineering. Such hydraulic breakers are classified into two types, a gas piston type and a full hydraulic type, depending on the operation method. In the former, the source of striking force is gas pressure or gas and hydraulic pressure, and it is used for large hydraulic breakers mounted on hydraulic excavators. In the latter, the source of impact force is only hydraulic pressure, and it is used for small hydraulic breakers such as hand breakers.

However, the characteristic of the gas piston type is that
When used with the same hydraulic power source, the number of impacts is greater and the impact force can be increased compared to the full hydraulic type, that is, the efficiency of converting hydraulic energy into impact energy is high. However, since the hammer piston directly presses the hammer piston with gas pressure to obtain a striking force, the rear end of the piston is inserted into the gas filling chamber. Therefore, the seal that prevents gas leakage is a piston rod seal, but since this gas seal is almost non-lubricated and slides at high speed, the operating conditions are extremely strict and even if a synthetic resin material with excellent characteristics is used. There is a problem of short life. In addition, gas leaks several dozen times more easily than oil, and gas leaks from the piston rod portion, so that gas must be refilled in a short period of time.

On the other hand, in the full hydraulic type, the gas is sealed in the gas chamber sealed by the diaphragm, so that gas leakage does not easily occur and the gas pressure can be maintained for a long period of time. However, since the hammer piston is hydraulically operated, the hydraulic oil flows at a high speed, resulting in a large loss, and there is no energy storage action when the piston is raised, resulting in a low energy efficiency. Therefore, as an eclectic method of the full hydraulic type and the gas piston type, a type has been developed in which an accumulator is provided at the upper end of the main body and the ergi accumulated in the accumulator is transmitted to the hammer piston via hydraulic oil.
However, in this method, the hydraulic oil in the oil chamber below the accumulator does not circulate, so the hydraulic oil breaker's operation of compressing and expanding the diaphragm causes the hydraulic oil in the oil chamber to reach a high temperature. Therefore, there is a problem in that the diaphragm is damaged and gas leakage easily occurs.

[0005]

SUMMARY OF THE INVENTION The present invention was made by research to solve the above-mentioned problems, and its purpose is to obtain a high striking force with a high energy efficiency. It is possible to provide a hydraulic breaker which is capable of preventing gas leakage and has excellent durability.

[0006]

In order to achieve the above object, the present invention provides a hammer piston in a main body having a tool attached to a lower portion thereof, and applies energy accumulated by an accumulator provided at an upper end of the main body to hydraulic oil. In a breaker of a type in which a hammer piston is actuated to strike a tool, an oil chamber under the accumulator, which communicates with the accumulator pressure storage chamber and faces the upper piston of the hammer piston, is defined through a partition wall, and the partition wall is formed. An annular oil chamber connected to the hydraulic oil inlet passage and a high pressure passage for operating the hammer piston is provided on the outer periphery, and on the outer side in the vicinity of the annular oil chamber,
An oil chamber control valve is provided for controlling the pressure in the oil chamber within a predetermined range and for gradually changing the hydraulic oil in the oil chamber little by little due to the pressure variation in the oil chamber due to the lifting stroke of the hammer piston.

The oil chamber control valve preferably includes a communication passage connected to the oil chamber, a low pressure passage connected to the hydraulic oil outlet passage,
A valve chamber connected to each high-pressure passage leading to the high-pressure passage, a valve body having a communication switching portion between the communication passage and the high-pressure passage, and a communication switching portion between the communication passage and the low-pressure passage, so that the communication passage and the high-pressure passage normally communicate with each other. Has a spring for urging the valve body, and the oil chamber control valve shuts off the communication passage and the high pressure passage by lowering the valve body due to the oil chamber pressure introduced from the top of the valve chamber. When the lower limit pressure is set and the oil chamber pressure reaches the upper limit set pressure with the rise of the hammer piston, the valve body further lowers, thereby connecting the communication passage and the low pressure passage to the hydraulic oil in the oil chamber. It is configured to lead to the passage. The partition wall is preferably made of a material having good thermal conductivity. Further, in the present invention, a control valve is provided below the oil chamber to switch the flow of hydraulic pressure by moving the hammer piston up and down. Preferably, the valve body of the control valve is concentric with the upper piston of the hammer piston. And has the same pressure receiving area at the upper end and the lower end.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show one embodiment of the hydraulic breaker according to the present invention, and FIGS. 6 to 9 show one cycle of striking operation. 1 is a main body, and in this embodiment, an upper body 1a, an intermediate body 1b, and a front end 1
It is divided into c and they are oil-tightly coupled by bolts or the like. A tool T such as a chisel is fitted to the front end 1c so as to be slidable in the axial direction, an accumulator 2 is attached to an upper body 1a as a top of the main body, and an operation handle (not shown) is provided below the accumulator 2. ing. A diaphragm 2a made of rubber or the like is stretched inside the accumulator 2, a gas G is enclosed inside the diaphragm 2a, and a pressure accumulating chamber 2 is provided below the diaphragm 2a.
01 is formed, and a large number of through holes 2 are formed in the bottom wall of the pressure accumulating chamber 201.
02 is provided. A hammer piston 3 is slidably arranged on the central axis of the main body 1. In the hammer piston 3, a lower piston 3d is continuously provided coaxially with the tool T below the piston portion 3a, and the lower piston 3d projects into the front end. The piston portion 3a has a constriction portion 3b for escape in the middle in the longitudinal direction.
An upper piston 3c is connected to the upper end of a. The piston portion 3a, the lower piston 3d, and the upper piston 3c
And the respective diameters are made to satisfy the relation W> W ₁ > W ₂ , and the diameter W ₃ of the constricted portion 3b is made equal to or larger than the diameter W ₁ of the lower piston 3b.

Reference numeral 4 is a control valve for automatically switching the flow of hydraulic pressure by raising and lowering the hammer piston 3. In this embodiment, an upper body 1a and an intermediate body 1b of the main body 1 are controlled.
It is located across the area. Control valve 4
Is provided with a valve chamber 4a having a tubular valve body 4b built therein.
Reference numeral 5 designates the valve chamber 4 in the upper body 1a immediately below the accumulator 2.
The upper piston 3c penetrates the hole of the partition wall 100 and projects into the center of the void space 5 through the partition wall 100a. The recess 5 has a ring-shaped partition wall 5a that concentrically surrounds the upper piston 3c. The partition wall 5a divides the recess 5 into two in the radial direction, and the recess 5 is located directly below the through hole 202. Oil chamber 50 containing the piston 3c
And an annular oil chamber 51 that does not communicate with the through hole 202 is formed in the periphery. The partition wall 5a is made of a material having a high thermal conductivity such as an aluminum alloy, and its upper and lower ends are oil-tightly sandwiched and fixed between the bottom partition wall of the accumulator 2 and the bottom wall of the oil chamber 50. The annular oil chamber 51
Is connected to a hydraulic oil inlet passage 6, and the hydraulic oil inlet passage 6 is guided to a hydraulic pressure supply source (not shown) via hoses. On the other hand, a hydraulic oil outlet passage 6'is provided below the control valve 5, and the hydraulic oil outlet passage 6'is connected to a tank (not shown) by hoses.

In order to control the pressure of the oil chamber 50 to a predetermined range at the outside of the annular oil chamber 51 and to gradually change the working oil in the oil chamber 50 by utilizing the lifting stroke of the hammer piston 3. An oil chamber control valve 7 is provided. Although the oil chamber control valve 7 is directly provided on the main body 1 in this embodiment, it is not limited to this and may be made as another block-shaped body and may be fixedly connected to the main body 1. Absent.

The oil chamber control valve 7 is, as shown in FIGS. 2 and 3,
Cylindrical valve chamber 7a and valve body slidably fitted in the valve chamber 7a
A spool 7b (for example, a spool) and a spring 7c for urging the valve body 7b are provided. The valve chamber 7a has an annular groove 70 on the peripheral wall of the intermediate region in the height direction, and the annular groove 70 is connected to the bottom of the oil chamber 50 by a communication passage 71. A part of the communication passage 71 has a branch passage 71 ', and the branch passage 71' communicates with an upper chamber 72 defined by the valve body 7b. A tip of a high-pressure passage 73 communicates with the peripheral wall of the valve chamber below the annular groove 70, and the high-pressure passage 73 is connected to the hydraulic oil inlet passage 6 via an annular oil chamber 51 as described later. . The lower end of the low pressure oil passage 74 communicates with the lower region of the valve chamber 7a, and the low pressure oil passage 74 is directly connected to the hydraulic oil outlet passage 6 ', or as shown in FIG. It is connected to the lower region of the valve chamber 4a.

The valve body 7b has a first land 75a at the top thereof, a second land 75c is formed below the first land 75a via a first rod portion 75b, and a second rod portion 75d is formed thereunder. A third land 75e is formed therethrough, and a third rod portion 75f is formed below the third land 75e for supporting and guiding the spring 7c. A plurality of through holes 750 are formed in the first rod portion 75b in the radial direction, and a cylindrical hole 751 is formed in the center of the valve body 7b from the lower end to the through hole 750. Are installed vertically. The valve body 7b is biased upward by a spring 7c interposed between the lower end surface of the third land 75e and the valve chamber bottom, and in the normal state, the second rod portion 75d causes the annular groove 70 and the high pressure oil passage 73 to move. It is located in an area that spans ports. Then, when the pressure of the oil chamber 50 is introduced into the upper chamber 72 and the valve body 7b overcomes the setting force of the spring 7c and descends, the high pressure oil passage 73 and the annular groove 7 are formed.
0 is blocked by the second land 75c, and at the same time, the first rod portion 75b faces the annular groove 70. The pressure when the high-pressure oil passage 20 and the annular groove 70 are blocked by the second land 75c is the lower limit set pressure, which can be arbitrarily adjusted by the setting force of the spring 7c.

As shown in FIGS. 2 and 5, the valve body 4b of the control valve 4 has a straight cylindrical hole 40 at the center thereof. Further, as shown in FIG. 5, a first rod portion 41 having an outer diameter d ₁ from the upper end to the lower end, a first land 42 having an outer diameter d ₃ , and a second land 43 having an outer diameter d ₂ are provided on the outer circumference. , A second rod portion 44 having an outer diameter of d ₁ is sequentially formed. The second rod portion 44 is provided with at least one small hole 440 communicating with the cylindrical hole 40. The diameters d ₁ of the first rod portion 41 and the second rod portion 44 are equal, and the first land 42
And the diameters d ₃ and d ₂ of the second land 43 are d ₃ > d _2, and the diameter d ₂ of the second land 43 is the same as that of the first rod portion 41.
And the diameter d ₁ of the second rod portion 44 and d ₂ > d ₁ . Therefore, in relation to the pressure receiving area, the first rod portion 41
Is equal to the pressure receiving area A ₁ of the end surface of the second rod portion 44, and the pressure receiving area of the upper end pressure receiving surface of the first land 42 is A ₂ .
When the pressure receiving area of the lower end pressure receiving surface of the land 42 is A ₃ and the pressure receiving area of the lower end pressure receiving surface of the second land 43 is A ₄ , the following relational expression is obtained. A ₂ = A ₄ + A ₃ (1) A ₄ = A ₂ −A ₃ (2) A ₃ = A ₂ −A ₄ (3)

On the other hand, in the valve chamber 4a, as shown in FIG.
The first rod portion 41 and the second rod portion 44 are provided on the upper and lower sides.
The upper and lower sliding contact surfaces 41 ′ and 44 ′ corresponding to the diameter of are provided, and between the upper and lower sliding contact surfaces 41 ′ and 44 ′,
The first valve chamber 4 which is in sliding contact with the first land 42 and has a ring-shaped groove larger than the length dimension of the first land 42.
5 and the second land 43 are slidable, and the second land 43
The second valve chamber 46 is formed of a ring-shaped groove having a length substantially equal to that of the second valve chamber 46. A cylinder hole 8 having a diameter with which the outer circumference of the piston 3a is slidably contacted is concentrically provided below the valve chamber 4a, and a region from the upper region of the cylinder hole 8 to the cylindrical hole 40 has a variable volume. Is the upper piston chamber 9. In addition, in the bottom region of the cylinder hole 8, the lower piston chamber 10 having a variable volume is formed between the lower end of the piston portion 3a and the lower piston chamber 10.
Are formed, and the lower piston chamber 10 and the upper piston chamber 9 are formed.
In the cylinder hole 8 between
Are formed.

A high pressure passage 12 extending from the annular oil chamber 51 is connected to a lower region of the lower piston chamber 10, and the high pressure passage 12 is connected to an upper sliding contact surface 41 'of the valve chamber 4a of the control valve 4. A first branch passage 120 communicating with the second branch passage 12 communicating with a lower region of the first valve chamber 45.
One. Further, the high pressure passage 12 is connected to the oil chamber control valve 7
Is connected to the high pressure passage 73. Next, the intermediate chamber 11 is connected to the upper region of the first valve chamber 45 by the communication passage 13. Further, a hydraulic oil outlet passage 6'is connected to a lower region of the second valve chamber 46, and a lower region of the second valve chamber 46 displaced circumferentially with a connecting portion of the hydraulic oil outlet passage 6 '. , The low pressure passage 7 of the oil chamber control valve 7
4 ends are connected. The hydraulic oil outlet passage 6'is branched from a low pressure passage 14 whose tip communicates with the cylinder hole 8 which is appropriately higher than the intermediate chamber 11. In the drawings, the high pressure passage 12, the communication passage 71, and the low pressure passage 74, and the communication passage 13 and the hydraulic oil outlet passage 6'are shown on the same cross section, but of course, they are drilled in different phases so that they do not actually intersect. It is set up. The high-pressure passage 12 is connected to the annular oil chamber 51 near the hydraulic oil inlet passage 6 in FIGS. 6 to 9, but preferably the anti-hydraulic oil inlet passage 6 as shown in FIGS. 1 and 2.
Is connected to the inner side of the annular oil chamber. By doing so, the hydraulic oil in the oil chamber 50 can be cooled more effectively.

The relationship between the hammer piston 3 and the passages will be described. When the hammer piston 3 descends and strikes the tool T, the lower portion of the constricted portion 3b faces the intermediate chamber 11 as shown in FIG. The chamber 11 and the low pressure passage 14 are communicated with each other, and the lower end of the piston portion 3a is located at the high pressure passage 1
It is in a position where port 2 is not blocked. At this time, the valve body 4b of the control valve 4 contacts the ceiling of the valve chamber with the upper limit position, that is, the end surface of the first rod portion 41 contacts the small hole 4b.
40 is in a state of communicating with the low pressure passage 14 via the second valve chamber 46. When the hammer piston 3 reaches the upper limit, the lower end of the piston portion 3a of the hammer piston 3 is located in the intermediate chamber 11, so that the intermediate chamber 11 and the lower piston chamber 10 are communicated with each other. At this time, the valve body 4b of the control valve 4 is held at the upper limit position. When the hammer piston 3 starts descending from this state, the lower end of the piston portion 3a closes the intermediate chamber 11,
At this time, the valve body 4b of the control valve 4 is in the lower limit position, that is, the end surface of the second rod portion 44 contacts the bottom of the valve chamber,
The first branch passage 120 communicates with the valve chamber 4a.

[0017]

Next, the operation of the hydraulic breaker according to the present invention will be described. When the working oil is introduced from the working oil inlet passage 6, the working oil flows into the annular oil chamber 51 and then flows from there to the high pressure passage 12. Therefore, the oil in the oil chamber 50 that is partitioned from the annular oil chamber 51 by the partition wall 5a is
Since the partition wall 5a is made of a material having a high thermal conductivity in a ring shape, heat is exchanged through the partition wall 5a. Therefore, the hydraulic oil in the oil chamber 50, which plays an important role in the hydraulic breaker, is cooled, so that the deterioration of the diaphragm and the hydraulic oil can be prevented.

When the pressure in the oil chamber 50 is lower than the set pressure, including when the hydraulic breaker is activated, the valve body 7b of the oil chamber control valve 7 is pushed upward by the setting force of the spring 7c and is moved upward as shown in FIG. 3 (a). It is in a state. Therefore, the oil that has passed through the annular oil chamber 51 branches from the high pressure passage 12 to the high pressure passage 73, and the communication passage 71 passes through the annular groove 70 of the valve chamber 7a.
And flows into the oil chamber 50. This allows the oil chamber 50
Pressure rises. The pressure of the oil chamber 50 is the communication passage 71.
Is transmitted to the upper chamber 72 from the branch passage 71 ′ of 7 to push the valve body 7 b down against the force of the spring 7 c. When the valve body 7b descends in this manner, the communication between the high pressure passage 73 and the annular groove 70 is blocked by the second land 75c of the valve body 7b.
The pressure at this time becomes the lower limit set pressure.

On the other hand, at the same time, the oil that has passed through the high pressure passage 12 is introduced into the lower piston chamber 10, so that the piston portion 3a is pressed upward and the hammer piston 3 rises. Due to the rise of the hammer piston 3, the upper piston 3c moves into the oil chamber 50.
The hydraulic oil in the oil chamber is compressed and the pressure rises as it enters. When the pressure exceeds the upper limit set pressure, the spring 7c is further compressed by the pressure in the upper chamber 72, and the valve body 7b is lowered. As a result, the state shown in FIG.
The annular groove 70 and the through hole 750 of the valve body 7b communicate with each other. Therefore, the hydraulic oil in the oil chamber 50 flows into the cylindrical hole 751 from the annular groove 70 and flows out from the lower end of the valve chamber to the low pressure passage 74. The low pressure passage 74 is provided in the second valve chamber 46 of the control valve 4.
The required amount of hydraulic oil in the oil chamber 50 is returned to the tank because it is connected to the hydraulic oil outlet passage 6 ′ via.

When the oil chamber control valve 7 is not provided, the pressure in the oil chamber 50 fluctuates between the upper limit and the lower limit of the waveform of FIG. 4 and becomes the pressure fluctuation range P ₁ . The range of this pressure fluctuation is determined by the diameter and stroke of the hammer piston 3, the volume of the oil chamber 50 and the volume of the accumulator 2, but the present invention sets the upper and lower pressure settings of the valve body 7b of the oil chamber control valve 7. A stable impact is obtained by setting the range P ₂ inside the pressure fluctuation range of FIG. 4, and the diaphragm 20 of the accumulator 2 is obtained.
0 damage can be prevented. More specifically, in the present invention, when the hammer piston 3 rises and the pressure in the oil chamber 50 reaches the upper limit set pressure, the state shown in FIG. The operation oil in the oil chamber 50 is pushed out by the operation of the body 7b. That is, the hydraulic oil remaining in the hammer piston 3 is pushed out of the system via the low pressure passage 74. Further, when the hammer piston 3 descends, when the pressure in the oil chamber 50 falls to the lower limit set pressure, the valve body 7b of the oil chamber control valve 7 becomes the state of FIG. The hydraulic oil for the remaining stroke of the piston 3 is replenished via the high pressure passage 74 and the communication passage 71. From the above, the pressure in the oil chamber 50 is always controlled within the pressure fluctuation range P ₂ that falls between the upper and lower set pressures in FIG. Therefore, the striking force of the hydraulic breaker can be made stable, and at the same time, the diaphragm 2a of the accumulator 2 has a slanted portion a in FIG.
Since the extra load of b does not work, the diaphragm 2
It is possible to prevent the damage of a and increase its durability. Furthermore, as is apparent from FIG. 3, the hydraulic oil in the oil chamber 50 is gradually pushed out and replenished in synchronism with the ascent and descent of the hammer piston 3, so that the hydraulic oil can be replaced by circulation and the hydraulic oil can be replaced. Can be prevented from deteriorating.

FIG. 6 shows a state in which the impact has been completed. In this state, the hydraulic oil that has flowed in from the hydraulic oil inlet passage 6 is in the annular oil chamber 5.
1, it flows into the lower piston chamber 10 through the high-pressure passage 12 and acts on the pressure-receiving surface at the upper end of the constricted portion 3b facing here to push up the hammer piston 3. At this time, a part of the hydraulic oil flows into the second valve chamber 46 of the control valve 4 via the second branch passage 121 branched from the high pressure passage 12, and the first land lower end pressure receiving surface A of the valve body 4b.
_Since it acts on ₃ , the valve body 4b is lifted to the upper limit position. A part of the hydraulic oil flows into the oil chamber 50 through the high pressure passage 73, the annular groove 70, and the communication passage 71. This oil chamber 50
Is also applied to the upper chamber 72 through the branch passage 71 ', and this pressure compresses the spring 7c and pushes down the valve body 7b. When the valve body 7b descends, the high pressure passage 73 and the communication passage 71 are blocked by the second land 75c. That is, when the pressure of the oil chamber 50 rises to a pressure at which the pressure of the upper chamber 72 and the force of the spring 7c are balanced, the pressure of the oil chamber 50 is cut off from the pressure of the hydraulic oil inlet passage 6, and this pressure is the minimum pressure of the oil chamber 50. Become.

The hammer piston 3 is pushed up as shown in FIG. 7 by the pressure acting on the lower piston chamber 10 described above. At this time, the hydraulic oil in the upper piston chamber 9 continuous with the valve chamber 7a of the control valve 4 is pushed out by the rise of the piston portion upper end pressure receiving surface of the hammer piston 4, and the lower portion of the second rod 44 of the valve body 4b. Through a small hole 440 provided in the second valve chamber 46, and returns to the external tank via the hydraulic oil outlet passage 6'opened there. At the same time, the upper piston 3c of the hammer piston 3 is pushed into the oil chamber 50. For this reason, the volume in the oil chamber 50 decreases, and the hydraulic oil whose pressure has risen is pushed out,
At this time, the communication passage 71 has the second land 75c of the valve body 7b.
Since it is blocked by the oil, the hydraulic oil acts exclusively above the oil chamber 50, flows in through a large number of through holes 202 provided in the bottom of the accumulator 2, pushes up the diaphragm 2a, and fills the diaphragm gas chamber. Gas G
Is moved to the pressure accumulating chamber 201 while being compressed. When the lower end of the piston portion 3a of the hammer piston 3 reaches the position of the intermediate chamber 11 in this way, the lower piston chamber 10 and the intermediate chamber 11 communicate with each other by the lower piston 3d, and the high-pressure hydraulic oil in the lower piston chamber 10 is transferred to the intermediate chamber 11. To the first valve chamber 45 of the control valve 4 via the communication passage 13 and the pressure thereof becomes high, so that the valve body 4b starts to descend.

More specifically, high pressure acts on the pressure receiving area A ₂ at the upper end of the first land 42 of the valve body 4b of the control valve 4, and the hydraulic oil inlet passage is at the pressure receiving area A ₃ at the lower end of the first land 42. 6 acts on the pressure receiving area A ₄ at the lower end of the second land 43.
The low pressure Pl that flows out from the hydraulic fluid outlet passage 6 ′ to the hydraulic oil outlet passage 6 ′ is always acting. The pressure receiving areas A ₁ of the first rod portion 41 and the second rod portion 44 are the same, and the same pressure is always applied, which cancels each other out. Thus the force Fd to be push down the control valve _{Fd = (A 2 × Ph)} - (A 3 × Ph) - (A 4 × Pl) = (A 2 -A 3) × Ph- (A 4 × Pl) Since A ₄ = A ₂ −A ₃ here, Fd = (A ₄ × Ph) −
(A ₄ × Pl) = A ₄ (Ph−Pl)> 0.

Due to the above relationship, the valve body 4b of the control valve 4 is lowered. Then, as shown in FIG.
0 is closed by the sliding contact wall 44 ', and at the same time, the space between the first branch passage 120 of the high pressure passage 12 and the valve chamber 4a is opened. Therefore, the high-pressure hydraulic oil flows into the upper piston chamber 9 and becomes high pressure. Volume of upper piston chamber 9 (piston 3
Since the pressure receiving area of the upper part of a) is set to be slightly larger than that of the lower piston chamber 10 (lower pressure receiving area of the piston portion 3a), the hammer piston 3 descends. Further, the oil pressure of the oil chamber 50 acts on the end surface 300 of the upper piston 3c of the hammer piston 3. Due to these synergistic effects, the hammer piston 3 is rapidly lowered and descends. The hydraulic oil is supplied to the oil chamber 50 from the pressure accumulating chamber 201 through a large number of small holes 202. The gas in the gas chamber expands and pushes down the diaphragm 200. At this time, the hydraulic oil in the lower piston chamber 10 is pushed out by the downward movement of the piston portion 3a, flows backward in the high pressure passage 12 and flows backward from the first branch passage 120 into the upper piston chamber 9.

Thus, the hammer piston 3 descends at a high speed, and the lower piston 3d strikes the head of the tool T as shown in FIG. The tool 11 transmits this impact energy, and according to its function, for example, crushes rock or concrete at the tip. When the hammer piston 3 descends to the position where it strikes the tool T, the constricted portion 3b provided in the piston portion 3a reaches the position of the intermediate chamber 11. As a result, the port of the communication passage 13 and the intermediate chamber 11 communicate with each other via the constricted portion 3b. Therefore, the control valve 4
Of the high pressure hydraulic oil in the first valve chamber 45 of the communication passage 13 →
It flows out from the intermediate chamber 11 to the low pressure passage 14 to the hydraulic oil outlet passage 6 ′, whereby the first valve chamber 45 becomes low pressure, and the ascending force Fu acts on the valve body 4 b. This rising force Fu is
It becomes as follows according to each pressure receiving area of the valve body 4b. Substitute Fu = (A ₄ × Pl) + (A ₃ × Ph) − (A ₂ × Pl) = (A ₃ × Ph) − (A ₂ −A ₄ ) Pl A ₃ = (A ₂ −A ₄ ). and _{Fu = a 3 (Ph-Pl} )> 0 thus the valve body 4b rises again, thereby returning to the state of FIG. 6, in which the same operation is repeated as described above. In addition,
In the hollow portion of the valve body 4b of the control valve 4, a violent pressure fluctuation occurs due to the striking action of the hammer piston 3, but the valve body 4b has the same diameter d ₁ of the first rod portion 41 and the second rod portion 44 at the upper and lower ends. Therefore, the force due to the pressure is always balanced, so that the pressure can be reliably operated without being affected by the pressure fluctuation.

[0026]

According to the first aspect of the present invention described above, in the hydraulic breaker of the type in which the energy accumulated in the accumulator is transmitted to the hammer piston through the hydraulic oil, the partition wall 5a is provided on the outer periphery of the oil chamber 50. In order to define the annular oil chamber 51 and introduce the hydraulic oil from the hydraulic oil inlet passage 6 into the annular oil chamber 51 and send it to the high pressure passage 12 for hammer piston operation,
The heat in the oil chamber 50 is released by the heat exchange through the partition wall 5a, and the oil that is taken in and out of the accumulator 2 can be appropriately cooled, and thus the deterioration of the diaphragm and the hydraulic oil can be prevented. Also, hammer piston 3
As the control valve 7 moves the oil chamber 50 in and out little by little as it moves up and down, deterioration of the hydraulic oil can be prevented.
Moreover, since the fluctuation of the pressure in the oil chamber 50 due to the elevation of the hammer piston 3 can be automatically controlled and kept within an appropriate range at all times, the striking force can be stabilized and the diaphragm 2a is damaged and Gas leakage can be prevented, and therefore, an excellent effect that a hydraulic breaker having high energy efficiency and good durability can be obtained.

According to the second aspect, since the partition wall 5a has good thermal conductivity, the temperature rise of the oil in the oil chamber can be suppressed,
The excellent effect that the deterioration of the diaphragm and the hydraulic oil can be prevented is obtained. According to claim 3, the excellent effect that the control of the pressure of the oil chamber 50 and the exchange of the hydraulic oil can be realized with a relatively simple structure is obtained. According to the fourth aspect, the valve body 4b is not excessively moved even by a drastic pressure change caused by the lifting and lowering of the hammer piston 3, and stable hydraulic pressure direction switching can be performed, and this can be realized by a simple structure. Excellent effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a hydraulic breaker according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is an explanatory view showing the operation of the oil chamber control valve in the present invention.

FIG. 4 is a diagram showing fluctuations in the pressure inside the oil chamber according to the present invention.

FIG. 5 is an explanatory diagram illustrating pressure receiving areas of respective portions of the valve body in the control valve of the present invention.

FIG. 6 is a cross-sectional view showing a state where the hammer piston has completed the impact of the tool and the ascending stroke has started in the present invention.

FIG. 7 is a sectional view showing a state during a rising stroke in the same manner.

FIG. 8 is a sectional view showing a descending stroke starting state.

FIG. 9 is a sectional view showing a state when the tool is hit.

[Explanation of symbols]

 1 Main body 2 Accumulator 2a Diaphragm 201 Accumulation chamber 3 Hammer piston 3c Upper piston 4 Control valve 4a Valve chamber 4b Valve body 5a Partition wall 50 Oil chamber 51 Annular oil chamber 6 Hydraulic oil inlet passage 6'Operating oil inlet passage 7 Oil chamber control valve 7a Valve chamber 7b Valve body 7c Spring 12 High pressure passage 71 Communication passage 72 Upper chamber 73 High pressure passage 74 Low pressure passage T Tool

Claims (4)

[Claims] 1. A hammer piston 3 is arranged in a main body having a tool T mounted on a lower portion thereof, and energy accumulated in an accumulator 2 provided at an upper end of the main body is applied to hydraulic oil to operate the hammer piston 3 to strike the tool T. In the breaker of the type in which the oil is added to the accumulator 2, the oil chamber 50 communicating with the accumulator pressure accumulating chamber 201 and facing the upper piston 3c of the hammer piston 3 is defined through the partition wall 5a, and the outer periphery of the partition wall is formed. An annular oil chamber 51 connected to each of the hydraulic oil inlet passage 6 and the high pressure passage 12 for operating the hammer piston 3 is provided.
An oil chamber control valve 7 is provided for controlling the pressure in the oil chamber 50 within a predetermined range and for gradually changing the hydraulic oil in the oil chamber little by little due to the pressure fluctuation in the oil chamber due to the lifting stroke of the hammer piston 3. And hydraulic breaker. 2. The hydraulic breaker according to claim 1, wherein the partition wall 5a is made of a material having good thermal conductivity. 3. The oil chamber control valve 7 includes a communication passage 71 connected to the oil chamber 50 and a low pressure passage 7 connected to the hydraulic oil outlet passage 6 '.
4, a valve chamber 7a to which a high pressure passage 73 communicating with the high pressure passage 12 is connected, respectively, the communication passage 71 and the high pressure passage 73.
The valve body 7b has a communication switching portion between the communication passage 71 and the low pressure passage 74, and the spring 7c for urging the valve body 7b so that the communication passage 71 and the high pressure passage 73 normally communicate with each other. The oil chamber control valve 7 shuts off the communication passage 71 and the high pressure passage 73 by setting the lower limit pressure by lowering the valve body 7b by the pressure of the oil chamber introduced from the top of the valve chamber. When the oil chamber pressure reaches the upper limit set pressure as it rises, the valve body 7b further lowers to connect the communication passage 71 and the low pressure passage 74 to each other, so that the working oil in the oil chamber 50 is fed to the working oil outlet passage 6 '. The hydraulic breaker according to claim 1, which is configured to lead. 4. A control valve 4 which is defined below the oil chamber 50 and switches the flow of hydraulic pressure by raising and lowering a hammer piston 3 is provided, and a valve body 4b of the control valve 4 is an upper piston of the hammer piston 3. The hydraulic breaker according to any one of claims 1 to 3, which has a cylindrical hole concentric with 3c and has an upper end portion and a lower end portion having the same pressure receiving area.