CN219888397U - Middle cylinder structure of breaking hammer for tunnel - Google Patents

Abstract

The utility model provides a middle cylinder structure of a breaking hammer for a tunnel, and belongs to the technical field of breaking hammers. The technical problems that grease is added into a breaking hammer for a tunnel and can leak to a middle cylinder body and the like are solved. The middle cylinder structure of the breaking hammer for the tunnel comprises a middle cylinder body and a piston, wherein a piston hole for accommodating the piston is formed in the middle cylinder body, the piston is installed in the piston hole and can move relative to the piston hole in the axial direction, a grease seal groove, a main grease seal groove and a first oil return groove are sequentially formed in the front end hole wall of the piston hole from front to back, a grease seal and a main grease seal are respectively arranged in the grease seal groove and the main grease seal groove, an oil return channel is further formed in the middle cylinder body, and the first oil return groove is communicated with the oil return channel. The utility model can effectively avoid the grease from leaking into the middle cylinder body.

Description

Middle cylinder structure of breaking hammer for tunnel

Technical Field

The utility model belongs to the technical field of breaking hammers, and particularly relates to a middle cylinder structure of a breaking hammer for a tunnel.

Background

Hydraulic breaking hammers are widely used in various breaking situations, among which cutting tunnels is one of them.

The breaking hammer comprises a front cylinder body, a drill rod arranged in the front cylinder body, a rear cylinder body for storing nitrogen, a middle cylinder body, a piston arranged in the middle cylinder body and a reversing valve for controlling oil circuit conversion, wherein a front working cavity and a rear working cavity are arranged between the piston and the middle cylinder body, oil circuit channels are arranged on the front working cavity and the rear working cavity, the front working cavity is communicated with a main oil circuit, a normally high pressure state is kept, the rear working cavity discharges oil when the piston returns, the rear working cavity is in a low pressure state, and oil is filled when the piston strokes, and the rear working cavity is in a high pressure state. In the return stage of the piston, the piston compresses nitrogen upwards under the action of high-pressure oil in the front working cavity, hydraulic oil in the rear working cavity flows back to the hydraulic oil tank through the reversing valve, when the piston rises to a certain position, the reversing valve reverses, and the high-pressure oil enters the rear working cavity; in the piston stroke stage, as the acting area of the hydraulic oil in the rear working cavity of the piston is larger than that of the front working cavity, the downward force is larger than the upward force, and the piston moves downwards under the combined action of the hydraulic pressure and the nitrogen pressure and strikes the drill rod; the front cylinder body also comprises an inner sleeve and an outer sleeve, and grease is added on the inner sleeve and the outer sleeve to lubricate the drill rod, so that friction is reduced. As in patent No. 201910261815.8, the patent name is chinese patent of a hydraulic breaking hammer, when the hydraulic breaking hammer is hit downwards, butter is added on the front cylinder to lubricate, and a main oil seal ring and a buffer seal ring are arranged on the front part of the middle cylinder, which is close to the front cylinder, to prevent hydraulic oil from leaking from the middle cylinder.

When the hydraulic breaking hammer is applied to a tunnel, the hydraulic breaking hammer is in an upward striking state of a drill rod head for a long time due to working requirements, which is contrary to the situation that the hydraulic breaking hammer works normally, the main oil seal sealing ring and the buffer sealing ring of the patent are difficult to prevent grease from leaking into the middle cylinder body, so that no grease is added at present, and the drill rod is required to deflect upwards due to insufficient lubrication of the grease, and the wear of the outer sleeve opening part and the drill rod single side is serious; if butter is added, butter in the front cylinder body can flow into the middle cylinder body along the piston by gravity to pollute hydraulic oil, and the piston of the hydraulic breaking hammer is affected to cause cylinder pulling.

Disclosure of Invention

Aiming at the defects of the prior art, the utility model aims to provide a middle cylinder structure of a breaking hammer for a tunnel, which is used for preventing butter from leaking into the middle cylinder body.

The aim of the utility model can be achieved by the following technical scheme: the utility model provides a well jar structure of quartering hammer for tunnel, includes well cylinder body and piston, be equipped with the piston hole that is used for holding the piston in the well cylinder body, the piston is installed in the piston hole and can be in the relative piston hole removal in the axial, have set gradually butter seal groove, main oil seal groove and first oil return groove from front to back on the front end pore wall of piston hole, butter seal groove and main oil seal groove have placed butter seal and main oil seal respectively, still be equipped with the oil return passageway on the well cylinder body, first oil return groove and oil return passageway intercommunication.

The utility model provides a quartering hammer for tunnel includes preceding cylinder body, well cylinder body and the back cylinder body that links to each other in proper order from the front to the back, and the drill rod is located preceding cylinder body, and the piston is located in the well cylinder body, stores nitrogen gas in the back cylinder body. When the breaking hammer for the tunnel works, the front working cavity is always communicated with high-pressure hydraulic oil, the oil return channel is directly communicated with low-pressure night oil, the hydraulic oil flows in from the front working cavity, and the hydraulic oil flows back to the oil tank through the oil return channel. The high-pressure oil in the front working cavity leaks out a certain amount of high-pressure hydraulic oil through the clearance between the piston and the inner wall of the middle cylinder body, the high-pressure oil is converged in the first oil return groove and flows back to the oil tank through the oil return channel, the main oil seal is arranged in front of the first oil return groove, the main oil seal prevents the hydraulic oil from continuing to leak forward, and the hydraulic oil in the middle cylinder body is prevented from leaking into the lower end of the piston and the front cylinder body. Because this quartering hammer is working in the tunnel, and the drill rod of this quartering hammer of during operation all is in the state of upwards striking for a long time, and the heat of striking leads to butter to melt and flows easily when meeting heat, in order to prevent the butter in the preceding cylinder body from leaking to well cylinder body, sets up the butter seal groove before main oil seal groove, and the butter seal of placing in the butter seal groove can avoid the butter to flow to inside the well cylinder body because of gravity, guarantees the purity of hydraulic oil.

Further, a first annular oil collecting groove and a buffer oil seal groove are sequentially formed in the wall of the piston hole from front to back, the first annular oil collecting groove and the buffer oil seal groove are located between the main oil seal groove and the first oil return groove, the first annular oil collecting groove is communicated with the oil return channel, and a buffer oil seal is placed in the buffer oil seal groove.

The buffer oil seal has the effect of buffering oil pressure in the middle cylinder body and has a certain effect of sealing hydraulic oil. Because the striking speed is high, the striking force is high, high-pressure oil is extruded by the piston, and a certain amount of high-pressure oil can leak from the first oil return groove to the buffer oil seal, the leaked high-pressure oil can be absorbed by the first annular oil collecting groove, and flows to the oil return channel to flow back to the oil tank, so that the hydraulic oil reaching the main oil seal is reduced, the main oil seal well prevents the hydraulic oil from leaking, the better sealing of the grease seal is ensured, and the grease is prevented from leaking into the middle cylinder body to be mixed with the hydraulic oil.

Further, the front end face of the middle cylinder body is provided with a first step hole coaxial with the middle cylinder body, the first step hole is located in front of the first annular oil collecting groove, a front piston sleeve is placed in the first step hole, the grease seal groove and the main grease seal groove are arranged on the inner peripheral wall of the front piston sleeve, the outer peripheral face of the front piston sleeve is provided with a plurality of seal grooves I, and sealing elements I are placed in the seal grooves I.

For better sealing, the structure is characterized in that the first annular oil collecting groove, the buffer oil seal groove and the first oil return groove are formed in the middle cylinder body, so that hydraulic oil is recovered more stably, the first oil seal groove, the main oil seal groove and the first sealing grooves are formed in the front piston sleeve, leakage of hydraulic oil in the middle cylinder body can be effectively prevented, grease can be prevented from flowing into the middle cylinder body, after the grease is added into the front cylinder body, the drill rod head can reduce friction with the front piston sleeve due to lubrication, and the front piston sleeve can better protect the middle cylinder body. The detachable structure of the front piston sleeve is convenient to maintain. The mutual cooperation of this scheme cooperates.

Further, the rear end face of the front piston sleeve is provided with a second step hole, the second step hole is located behind the main oil seal groove, an opening groove I is formed in the hole bottom face of the second step hole and the hole bottom face of the first step hole, a supporting ring I is placed in the opening groove I, the front part of the inner peripheral face of the front piston sleeve is provided with a dustproof seal groove, a dustproof seal is placed in the dustproof seal groove, and the yellow oil seal groove and the main oil seal groove are located between the dustproof seal groove and the second step hole.

The dust seal prevents dust at the lower end of the piston from entering the hydraulic oil in the middle cylinder body, thereby playing a role in dust prevention. The material of the first supporting ring is preferably polytetrafluoroethylene or copper, has relatively hard hardness and good wear resistance, and can play a role in supporting and guiding the piston; because the hardness of the first supporting ring is lower than that of the piston, the first supporting ring is worn out for a while, so that the piston is protected and the napping is prevented. The support ring ensures the centering of the piston and improves the sealing effect.

Further, the length H1 of the front piston sleeve is larger than the hole depth H2 of the first step hole, and the front end face of the front piston sleeve abuts against the rear end face of the front cylinder body.

The front piston sleeve of this scheme is installed in first step hole, and the preceding tip supports with the rear end face of preceding cylinder body and leans on, deformation and the shake that causes when having reduced the piston impact for preceding piston sleeve is more stable when the piston strikes, and sealed effect is better.

Further, the front end surface of the middle cylinder body is outwards protruded with an annular boss, and the outer peripheral surface of the front end of the front piston sleeve is abutted against the inner peripheral surface of the annular boss.

The stability of preceding piston sleeve has been increased to this scheme, has reduced deformation and shake that causes when the piston strikes for sealed effect is better.

Further, the inner diameter of the first supporting ring is smaller than the inner diameter of the front piston sleeve. The first supporting ring is contacted with the piston, and the first supporting ring is lower in hardness than the piston, so that the first supporting ring is consumed for a while due to abrasion, and the piston is protected and napping is prevented. The support ring ensures the centering of the piston and improves the sealing effect.

Further, the rear end face of the middle cylinder body is provided with a third step hole, a first rear piston sleeve and a second rear piston sleeve are sequentially arranged between the hole wall of the third step hole and the outer peripheral face of the piston from front to back, the first rear piston sleeve is provided with an oil return hole, the oil return hole is communicated with an oil return channel, the first rear piston sleeve is in sealing connection with the middle cylinder body and the piston, and the second rear piston sleeve is in sealing connection with the middle cylinder body and the piston.

Further, a first stele seal groove is formed in the inner peripheral surface of the first rear piston sleeve, a first stele seal is placed in the first stele seal groove, a second seal groove is formed in the outer peripheral surface of the first rear piston sleeve, a second seal piece is placed in the second seal groove, a fourth step hole, a second stele seal groove and a gas seal groove are sequentially formed in the inner peripheral surface of the second rear piston sleeve from front to back, an opening groove II is formed in the rear end surface of the fourth step hole and the rear piston sleeve, a supporting ring II is placed in the opening groove II, a second stele seal is placed in the second stele seal groove, a gas seal is placed in the gas seal groove, a third seal groove is arranged in the outer peripheral surface of the second rear piston sleeve, and the oil return hole is located between the opening groove II and the first stele seal groove.

The scheme is that the second supporting ring and the second supporting ring together play a role in mutual correspondence, and the second supporting ring together guide the piston to ensure the centering of the piston, and the inner diameter of the second supporting ring is smaller than the inner diameters of the first rear piston sleeve and the second rear piston sleeve; in order to better mount the second support ring, the second support ring is placed on an opening groove formed in the fourth step hole and the rear end face of the first rear piston sleeve, so that the problem that the second support ring cannot be mounted into the piston sleeve due to the material problem is solved; according to the scheme, the first rear piston sleeve is provided with the oil return hole, the oil return hole is communicated with the oil return channel, when a tunnel is hit by a breaking hammer upwards, high-pressure oil is arranged in the rear oil cavity, when the piston moves rapidly, the high-pressure oil can infiltrate into a gap between the inner peripheral surface of the piston sleeve and the outer peripheral surface of the piston, the high-pressure oil in the gap flows to the oil return channel through the oil return hole, the high-pressure oil is changed into low-pressure oil, the purpose of reducing pressure is achieved, the continuous backward flowing effect of the high-pressure oil is avoided, and the leakage of the hydraulic oil is prevented; according to the scheme, the first rear piston sleeve and the second rear piston sleeve are propped against each other back and forth, the propped position is adjacent to the oil return hole, the preferred propped position is opposite to the oil return groove, namely, the propped position is located in the width of the notch of the oil return groove, when the piston moves rapidly, high-pressure oil permeates into the gap between the first rear piston sleeve and the second rear piston sleeve, and oil flows to the oil return channel through the gap, so that the high-pressure oil is prevented from continuing to flow backwards, and leakage of hydraulic oil is prevented.

Further, the hole wall of the third step hole is inwards sunken to be provided with an oil inlet groove, the front end of the oil inlet groove is provided with a middle cylinder step, the front end of the first rear piston sleeve is provided with an extension part, and the front part of the extension part is abutted to the step surface of the middle cylinder step.

According to the scheme, the middle cylinder step is arranged at the left end of the oil inlet groove, the end part of the extension part is abutted to the step surface of the middle cylinder step, so that the rear piston sleeve is more stable, the vibration of the rear piston sleeve can be well prevented, the deformation and vibration of the rear piston sleeve caused by hydraulic oil impact are reduced, and the service life of the rear piston sleeve is prolonged.

Compared with the prior art, the utility model has the technical effects that: 1. grease can be added to lubricate the drill rod, so that abrasion is reduced, and the durability of hydraulic breaking in the working of a hammer tunnel is improved. 2. The buffer oil seal groove and the first oil return groove are arranged on the middle cylinder body, so that the hydraulic oil is recovered more stably, the dustproof seal groove, the yellow oil seal groove, the main oil seal groove and the first sealing grooves are arranged on the front piston sleeve and are mutually matched in a cooperation mode, leakage of hydraulic oil in the middle cylinder body can be effectively prevented, grease can be prevented from flowing into the middle cylinder body, and the detachable structure of the front piston sleeve is convenient to maintain; 3. the supporting ring I and the supporting ring II support the piston back and forth, so that the centering of the piston is improved, the abrasion of parts is reduced, the sealing effect is better, and the working performance and the service life of the piston are improved.

Drawings

Fig. 1 is a half cross-sectional view of the present utility model.

FIG. 2 is an enlarged view of A-A of the present utility model.

Fig. 3 is a half cross-sectional view of the front piston sleeve of the present utility model.

Fig. 4 is a half cross-sectional view of the middle cylinder of the present utility model.

FIG. 5 is an enlarged view of B-B of the present utility model.

Fig. 6 is a half cross-sectional view of the rear piston sleeve one of the present utility model.

Fig. 7 is a half cross-sectional view of a rear piston sleeve II of the present utility model.

Fig. 8 is an exploded view of the present utility model.

Drawing number marks: 1. a middle cylinder; 101. a piston bore; 102. a first stepped hole; 103. buffer oil seal grooves; 104. a first oil return groove; 105. an oil return passage; 106. a first annular oil sump; 107. an annular boss; 108. a third stepped hole; 109. an oil inlet groove; 110. a middle cylinder step; 2. a piston; 3. a front working chamber; 4. a front piston sleeve; 401. dustproof sealing grooves; 402. a grease seal groove; 403. a main oil seal groove; 404. a first seal groove; 405. a second stepped hole; 5. buffering oil seal; 6. a dust seal; 7. a yellow oil seal; 8. a main oil seal; 9. a first sealing element; 10. a first supporting ring; 11. a rear piston sleeve I; 1101. a first stoneley seal groove; 1102. sealing grooves II; 1103. an oil return hole; 1104. an extension; 12. a second rear piston sleeve; 1201. a fourth stepped hole; 1202. a second stent sealing groove; 1203. a gas seal groove; 1204. sealing grooves III; 13. a first stoneley seal; 14. a second sealing element; 15. a second supporting ring; 16. a second stoneley seal; 17. hermetically sealing; 18. a third sealing member; 19. a front cylinder; 20. a rear cylinder; 21. a drill rod; 22. a jacket;

Detailed Description

The following are specific embodiments of the present utility model and the technical solutions of the present utility model will be further described with reference to the accompanying drawings, but the present utility model is not limited to these embodiments.

As shown in fig. 1 and 2, the middle cylinder structure of the breaking hammer for the tunnel comprises a middle cylinder body 1 and a piston 2, wherein a piston hole 101 for accommodating the piston 2 is arranged in the middle cylinder body 1, the piston 2 is installed in the piston hole 101 and can move relative to the piston hole 101 in the axial direction, the front part of the middle cylinder body 1 is connected with the rear part of a front cylinder body 19, a drill rod 21 is arranged in the front cylinder body 19, and nitrogen is stored in the rear cylinder body 20. An outer sleeve 22 and an inner sleeve are arranged between the drill rod 21 and the front cylinder body 19, and a butter hole is arranged on the front cylinder body 19 for pouring butter. The front working chamber 3 is arranged between the middle cylinder body 1 and the piston, the front working chamber 3 is directly communicated with high-pressure hydraulic oil, a plurality of communicated oil return channels 105 are arranged on the middle cylinder body 1, the oil return channels 105 are directly communicated with low-pressure night oil, the hydraulic oil flows in from the front working chamber 3, and the hydraulic oil flows back to an oil tank from the oil return channels 105. The front end surface of the middle cylinder 1 is outwardly protruded with an annular boss 107.

As shown in fig. 3, a dustproof seal groove 401, a grease seal groove 402, a main grease seal groove 403, a first annular oil collecting groove 106, a buffer grease seal groove 103 and a first oil return groove 104 are sequentially arranged on the front end hole wall of the piston hole 101 from front to back, the dustproof seal 6 is placed in the dustproof seal groove 401, the grease seal 7 is placed in the grease seal groove 402, the main grease seal 8 is placed in the main grease seal groove 403, and the buffer grease seal 5 is placed in the buffer grease seal groove 103. The first oil return groove 104 and the first annular oil sump 106 are both in communication with the oil return passage 105, and the hydraulic oil collected by the first oil return groove 104 and the first annular oil sump 106 flows out through the oil return passage 105. The buffer oil seal 5 has an effect of buffering oil pressure in the middle cylinder body 1, and has a certain effect of sealing hydraulic oil. The grease seal 7 is placed in the grease seal groove 402, and the grease seal 7 can seal grease well, so that the purity of hydraulic oil is ensured. The main oil seal 8 prevents the hydraulic oil from continuing to leak forward, and prevents the hydraulic oil inside the middle cylinder 1 from leaking into the lower end of the piston 2 and the front cylinder 19. The buffer oil seal 5 has an effect of buffering oil pressure in the middle cylinder body 1, and has a certain effect of sealing hydraulic oil.

In order to achieve better sealing protection, the front end face of the middle cylinder body 1 is provided with a first step hole 102 coaxial with the middle cylinder body 1, the first step hole 102 is positioned in front of a first annular oil collecting groove 106, a front piston sleeve 4 is arranged in the first step hole 102, and the first annular oil collecting groove 106, a buffer oil seal groove 103 and a first oil return groove 104 are arranged on the inner wall of the middle cylinder body 1, so that hydraulic oil recovery is more stable; the oil seal groove 402 and the main oil seal groove 403 are arranged on the inner peripheral wall of the front piston sleeve 4, the outer peripheral surface of the front piston sleeve 4 is also provided with a plurality of seal grooves I404, and a seal piece I9 is arranged in the seal groove I404. Not only can the leakage of the hydraulic oil in the middle cylinder body 1 be effectively prevented, but also the grease can be prevented from flowing into the middle cylinder body 1, and the disassembly and the maintenance are convenient.

As shown in fig. 3 and 4, the front piston sleeve 4 is of a circular ring structure, the front piston sleeve 4 is sleeved outside the piston, the outer peripheral surface of the front piston sleeve 4 is attached to the hole wall of the first step hole 102, a plurality of seal grooves 404 arranged on the outer peripheral surface of the front piston sleeve 4 can seal the front piston sleeve with the middle cylinder body 1, an annular dustproof seal groove 401, a yellow oil seal groove 402, a main oil seal groove 403 and a second step hole 405 are sequentially arranged on the inner peripheral wall of the front piston sleeve 4 from front to back, the second step hole 405 is punched on the rear end surface of the front piston sleeve 4 and is guaranteed to be coaxial with the front piston sleeve 4, a first support ring 10 is arranged in the first opening groove, and the material of the first support ring 10 is preferably polytetrafluoroethylene or copper. The length H1 of the front piston sleeve 4 is greater than the hole depth H2 of the first stepped hole 102, and the front end surface of the front piston sleeve 4 abuts against the rear end surface of the front cylinder 19. The front end surface of the middle cylinder body 1 protrudes outwards with an annular boss 107, and the outer peripheral surface of the front end of the front piston sleeve 4 abuts against the inner peripheral surface of the annular boss 107. The inner diameter of the first support ring 10 is smaller than the inner diameter of the front piston sleeve 4.

As shown in fig. 2, 5, 6, 7 and 8, a third step hole 108 is formed in the rear end face of the middle cylinder body 1, a first rear piston sleeve 11 and a second rear piston sleeve 12 are sequentially arranged between the hole wall of the third step hole 108 and the outer peripheral face of the piston from front to back, an oil return hole 1103 is formed in the first rear piston sleeve 11, the oil return hole 1103 is communicated with an oil return channel 105, the first rear piston sleeve 11 is in sealing connection with the middle cylinder body 1 and the piston 2, and the second rear piston sleeve 12 is in sealing connection with the middle cylinder body 1 and the piston 2. The inner peripheral surface of the first rear piston sleeve 11 is provided with a first Stirling seal groove 1101, a first Stirling seal 13 is placed in the first Stirling seal groove 1101, the outer peripheral surface of the first rear piston sleeve 11 is provided with a second seal groove 1102, the second seal groove 1102 is provided with a second seal member 12, the inner peripheral surface of the second rear piston sleeve 12 is sequentially provided with a fourth step hole 1201, a second Stirling seal groove 1202 and an air seal groove 1203 from front to back, the fourth step hole 1201 and the rear end surface of the first rear piston sleeve 11 form an opening groove II, a supporting ring II 15 is placed in the opening groove II, a second Stirling seal 16 is placed in the second Stirling seal groove 1202, an airtight seal 17 is placed in the airtight seal groove 1203, the outer peripheral surface of the second rear piston sleeve 12 is provided with a third seal groove 1204, the third seal groove 1204 is provided with a third seal member 18, and the oil return hole 1103 is positioned between the opening groove II and the first Stirling seal groove 1101. The wall of the third step hole 108 is inwards recessed with an oil inlet groove 109, the front end of the oil inlet groove 109 is provided with a middle cylinder step 110, the front end of the rear piston sleeve I11 is provided with an extension part 1104, and the front part of the extension part 1104 is abutted against the step surface of the middle cylinder step 110.

The middle cylinder structure of the breaking hammer for the tunnel can enable the grease lubrication drill rod 21 to be added into the front cylinder body 19, so that abrasion is reduced, the durability of hydraulic breaking in the tunnel operation of the hammer is improved, grease can be sealed, and the working performance and the service life of the piston are improved.

The above embodiments are only preferred embodiments of the present utility model, and are not intended to limit the scope of the present utility model in this way, therefore: all equivalent changes in structure, shape and principle of the utility model should be covered by the protection scope defined by the claims.

Claims (10)

1. The utility model provides a well jar structure of quartering hammer for tunnel, includes well cylinder body (1) and piston (2), be equipped with in well cylinder body (1) and be used for holding piston hole (101) of piston (2), piston (2) are installed in piston hole (101) and can be in the axial relative piston hole (101) removal, its characterized in that: the piston is characterized in that a grease seal groove (402), a main grease seal groove (403) and a first oil return groove (104) are sequentially formed in the front end hole wall of the piston hole (101) from front to back, a grease seal (7) and a main grease seal (8) are respectively arranged in the grease seal groove (402) and the main grease seal groove (403), an oil return channel (105) is further formed in the middle cylinder body (1), and the first oil return groove (104) is communicated with the oil return channel (105).

2. The middle cylinder structure of a breaking hammer for a tunnel according to claim 1, wherein: the piston is characterized in that a first annular oil collecting groove (106) and a buffer oil seal groove (103) are sequentially formed in the hole wall of the piston hole (101) from front to back, the first annular oil collecting groove (106) and the buffer oil seal groove (103) are located between the main oil seal groove (403) and the first oil return groove (104), the first annular oil collecting groove (106) is communicated with the oil return channel (105), and a buffer oil seal (5) is arranged in the buffer oil seal groove (103).

3. The middle cylinder structure of a breaking hammer for a tunnel according to claim 2, wherein: the novel oil seal device is characterized in that a first step hole (102) coaxial with the middle cylinder body (1) is formed in the front end face of the middle cylinder body (1), the first step hole (102) is located in front of a first annular oil collecting groove (106), a front piston sleeve (4) is placed in the first step hole (102), a yellow oil seal groove (402) and a main oil seal groove (403) are formed in the inner peripheral wall of the front piston sleeve (4), a plurality of first sealing grooves (404) are formed in the outer peripheral face of the front piston sleeve (4), and a first sealing piece (9) is placed in the first sealing grooves (404).

4. A middle cylinder structure of a breaking hammer for tunnel according to claim 3, characterized in that: the front piston sleeve (4) rear end face be provided with second step hole (405), second step hole (405) are located the rear of main oil seal groove (403), second step hole (405) are formed open slot one with the hole bottom surface of first step hole (102), support ring one (10) has been placed in the open slot one, the inner peripheral surface front portion of front piston sleeve (4) set up dustproof seal groove (401), dustproof seal (6) have been placed in dustproof seal groove (401), yellow oil seal groove (402) and main oil seal groove (403) are located between dustproof seal groove (401) and second step hole (405).

5. The middle cylinder structure of a breaking hammer for a tunnel according to claim 4, wherein: the length H1 of the front piston sleeve (4) is larger than the hole depth H2 of the first step hole (102), and the front end face of the front piston sleeve (4) abuts against the rear end face of the front cylinder body (19).

6. The middle cylinder structure of a breaking hammer for a tunnel according to claim 5, wherein: the front end surface of the middle cylinder body (1) is outwards protruded with an annular boss (107), and the outer peripheral surface of the front end of the front piston sleeve (4) is abutted against the inner peripheral surface of the annular boss (107).

7. The middle cylinder structure of a breaking hammer for a tunnel according to claim 4, wherein: the inner diameter of the first supporting ring (10) is smaller than that of the front piston sleeve (4).

8. The middle cylinder structure of a breaking hammer for tunnel according to any one of claims 1 to 7, wherein: the oil return device is characterized in that a third step hole (108) is formed in the rear end face of the middle cylinder body (1), a first rear piston sleeve (11) and a second rear piston sleeve (12) are sequentially arranged between the hole wall of the third step hole (108) and the outer peripheral face of the piston (2) from front to back, an oil return hole (1103) is formed in the first rear piston sleeve (11), the oil return hole (1103) is communicated with an oil return channel (105), the first rear piston sleeve (11) is in sealing connection with the middle cylinder body (1) and the piston (2), and the second rear piston sleeve (12) is in sealing connection with the middle cylinder body (1) and the piston (2).

9. The middle cylinder structure of a breaking hammer for a tunnel according to claim 8, wherein: the novel piston comprises a first piston sleeve (11), a first Stirling seal groove (1101) is formed in the inner peripheral surface of the first piston sleeve (11), a first Stirling seal (13) is placed in the first Stirling seal groove (1101), a second seal groove (1102) is formed in the outer peripheral surface of the first piston sleeve (11), a third seal groove (1204) is arranged on the outer peripheral surface of the second piston sleeve (12), a fourth stepped hole (1201), a second Stirling seal groove (1202) and an air seal groove (1203) are sequentially formed in the inner peripheral surface of the second piston sleeve (12) from front to back, an opening groove II is formed in the fourth stepped hole (1201) and the rear end surface of the first piston sleeve (11), a supporting ring II (15) is placed in the opening groove II, a second Stirling seal (16) is placed in the second Stirling seal groove (1202), an airtight seal (17) is placed in the airtight seal groove (1203), a third seal groove (1204) is arranged on the outer peripheral surface of the second piston sleeve (12), and the third seal groove (1204) is placed between the opening groove II and the first Stirling seal groove (1101).

10. The middle cylinder structure of a breaking hammer for a tunnel according to claim 9, wherein: the hole wall of the third step hole (108) is inwards sunken to be provided with an oil inlet groove (109), the front end of the oil inlet groove (109) is provided with a middle cylinder step (110), the front end of the rear piston sleeve I (11) is provided with an extension part (1104), and the front part of the extension part (1104) is propped against the step surface of the middle cylinder step (110).