A middle cylinder guide structure of a hydraulic breaker

Abstract

The present invention relates to the technical field of hydraulic equipment, and in particular to a guide structure of a middle cylinder of a hydraulic breaker. It comprises a middle cylinder body and a piston, wherein the inner circumference of the middle cylinder body is provided with front and rear chambers, the middle cylinder body is provided with a guide sleeve and a sealing sleeve, and the guide sleeve, the sealing sleeve and the middle cylinder body are equipped with an independent high-pressure oil lubrication system. The front guide sleeve and the front sealing sleeve are located at the front end of the middle cylinder body, and the rear guide sleeve and the rear sealing sleeve are located at the rear end of the middle cylinder body. The guide sleeve and the piston are matched with each other in clearance, so that the piston slides back and forth on the inner circumference of the guide sleeve. The high-pressure oil lubrication system continuously provides high-pressure oil for the clearance between the inner circumference of the guide sleeve and the piston. This structure avoids direct contact between the piston and the middle cylinder body during the return stroke, solves the problem of strain between the piston and the middle cylinder body, and when the guide sleeve is worn, it can be directly replaced at a low cost. At the same time, the high-pressure oil lubrication system plays an effective supporting and lubricating role in the centering operation of the piston. The use of the present invention can greatly extend the service life of the middle cylinder body and reduce maintenance costs.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic breaker hammers, and in particular to a middle cylinder guide structure of a hydraulic breaker hammer. Background Art

[0002] The hydraulic breaker uses liquid pressure as its motive force to drive the piston to reciprocate. The piston stroke hits the drill rod at high speed, and the drill rod breaks solids such as ore and concrete. It is usually installed on an excavator for use.

[0003] In the prior art, a hydraulic breaker is mainly composed of a front cylinder, a drill rod in the front cylinder, a middle cylinder, a piston in the middle cylinder, a reversing valve on the middle cylinder, and a rear cylinder. Through the stroke and return stroke of the piston, the piston repeatedly strikes the drill rod to achieve the crushing operation. When the piston reciprocates, the front and rear ends of the inner hole of the middle cylinder play a centering support role for the piston. During the use of the equipment, there is a large gap between the drill rod and the outer guide sleeve of the drill rod, and the drill rod is often in an offset axial state. When the piston impacts the drill rod with an offset axial center, it will be subjected to radial force, causing the piston to move eccentrically. At this time, the guide support area between the piston and the middle cylinder becomes smaller, and the pressure at the contact point increases. The piston squeezes the lubricating oil film, causing the piston to directly contact the middle cylinder, causing the middle cylinder to be damaged and scrapped. Replacing the middle cylinder of a medium or large hydraulic breaker costs tens of thousands to hundreds of thousands, and the maintenance cost is extremely high.

[0004] At present, the China Patent Network has published a hydraulic breaker cylinder structural component [authorization publication number: CN110067277A], which is provided with a piston ring at the rear end of the inner hole of the cylinder body and a gap sealing section or a sealing groove on the piston ring. During operation, high-pressure oil is always passed through the gap sealing section or the sealing groove, so that the seal cooperates more closely with the piston under the action of the high-pressure oil, and plays a centering support role for the middle and rear sections of the piston, avoiding direct contact between the piston and the inner hole of the cylinder body, which causes the piston and the cylinder body to be strained. Since the invention only sets a piston ring at the rear end of the inner hole of the cylinder body, when the piston moves off the axis, the piston and the front end of the inner hole of the cylinder body will still break through the oil film and directly contact, causing the piston and the cylinder body surface to be strained. At the same time, the seal at the front end of the cylinder body and the seal on the rear piston ring are easily damaged due to long-term extrusion of high-pressure oil. Damage to the seal will also cause the piston to directly contact the inner hole of the cylinder body and cause strain. In addition, since the high-pressure oil in the gap sealing section cannot flow continuously, the high-pressure oil cannot play a role in cleaning and cooling.

[0005] In order to completely isolate the contact between the piston and the middle cylinder body, a hydraulic breaker hammer [authorization publication number: CN110219334A] published by China Patent Network is provided with a guide sleeve at the front end of the inner hole of the middle cylinder body or / and a piston sleeve at the rear end of the inner hole of the middle cylinder body. The piston is movably arranged in the guide sleeve. This structure avoids direct contact between the piston and the middle cylinder body. At the same time, an oil collecting groove is provided on the guide sleeve to prevent the high-pressure oil from directly acting on the sealing ring, thereby improving the service life of the sealing ring. This patent utilizes the centering support effect of the guide sleeve or piston sleeve on the piston, but when the piston returns, the oil is returned to the rear cavity of the middle cylinder body, and the gap between the inner circumference of the rear guide sleeve or rear piston sleeve and the piston is subjected to low pressure. There is a lack of support and lubrication of stable high-pressure oil between the guide sleeve or piston sleeve and the piston. When the oil film pressure between the guide sleeve or piston sleeve and the piston is insufficient to support the dead weight of the piston and the external lateral force, the piston is easy to break through the oil film and directly contact the guide sleeve during the return stroke, causing wear of the piston and the guide sleeve. In addition, in order to make the oil pressure in the chamber uniform and improve the piston concentricity, the patent arranges a number of oil inlet holes at intervals around the guide sleeve. At the same time, a threaded hole for disassembly is opened on the front end face of the guide sleeve. When replacing the guide sleeve, it is necessary to screw the bolt into the threaded hole and then pull the bolt outward to pull out the guide sleeve, which makes it difficult to replace the guide sleeve. The several oil inlet holes arranged at intervals around the guide sleeve and the threaded holes opened on the front end face also increase the difficulty of processing the guide sleeve. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a middle cylinder guide structure for a hydraulic breaker, which avoids direct contact between the piston and the inner hole of the middle cylinder body during the return stroke, solves the problem of strain on the piston and the middle cylinder body, increases the service life of the piston and the middle cylinder body, reduces maintenance costs, and increases economic benefits.

[0008] (II) Technical solution

[0009] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0010] The present invention provides a middle cylinder guide structure of a hydraulic breaker, comprising a middle cylinder body and a piston, wherein the inner circumference of the middle cylinder body is provided with a front chamber and a rear chamber, the middle cylinder body is provided with a guide sleeve and a sealing sleeve, and the guide sleeve, the sealing sleeve and the middle cylinder body are equipped with an independent high-pressure oil lubrication system; wherein,

[0011] The front guide sleeve and the front sealing sleeve are located at the front end of the middle cylinder body;

[0012] The rear guide sleeve and the rear sealing sleeve are located at the rear end of the middle cylinder body;

[0013] The guide sleeve and the piston are matched with each other in clearance, and the piston slides back and forth in the guide sleeve;

[0014] The high-pressure oil lubrication system includes a front high-pressure oil lubrication system and a rear high-pressure oil lubrication system. The high-pressure oil lubrication system continuously provides high-pressure oil to the gap between the inner circumference of the guide sleeve and the piston.

[0015] According to the present invention, the front high-pressure oil lubrication system comprises a first oil return passage, a second oil return passage, a first oil return hole and a first oil return groove;

[0016] The rear high-pressure oil lubrication system includes an oil inlet passage, an oil inlet hole, an oil inlet groove, a second oil return groove, a fifth oil return passage, a third oil return passage, and a fourth oil return passage;

[0017] The oil return hole 1 and the oil return groove 1 are arranged on the front sealing sleeve; the oil inlet hole, the oil inlet groove and the oil return groove 2 are arranged on the rear guide sleeve; the rear guide sleeve cooperates with the rear sealing sleeve to form the oil return passage 5; the oil inlet passage, the oil return passage 3 and the oil return passage 4 are arranged on the middle cylinder body;

[0018] The oil return passage 1 and the oil return passage 2 are connected to the oil return hole 1; the oil inlet passage is connected to the oil inlet hole; the oil return passage 5 is connected to the oil return passage 3 and the oil return passage 4;

[0019] The high-pressure oil in the front chamber reaches the oil return groove 1 through the gap between the inner circumference of the front guide sleeve and the piston, and then flows back to the oil return channel 1 and the oil return channel 2 through the oil return hole 1; the oil inlet channel continues to pass the high-pressure oil to the oil inlet hole, and the high-pressure oil enters the gap between the inner circumference of the rear guide sleeve and the piston and reaches the oil return groove 2, and then flows back to the oil return channel 3 and the oil return channel 4 through the oil return channel 5.

[0020] According to the present invention, the oil return hole 1 is arranged on the right side of the sealing ring on the front sealing sleeve; the oil inlet hole is arranged between the sealing rings on the rear guide sleeve; the front end surface of the rear sealing sleeve is provided with a groove, and the rear end surface of the rear guide sleeve cooperates with the groove on the rear sealing sleeve to form an oil return channel 5.

[0021] According to the present invention, a plurality of grooves are further provided on the inner circumference of the guide sleeve. The inner circumference of the front guide sleeve cooperates with the piston to form a gap sealing section A, and the inner circumference of the rear guide sleeve cooperates with the piston to form a gap sealing section B.

[0022] According to the present invention, annular step surfaces are also provided on the inner circumferential surfaces of the front and rear ends of the middle cylinder body;

[0023] The front step end face of the front sealing sleeve is flush with the front end face of the middle cylinder body, the rear end face of the front sealing sleeve is pressed together with the front end face of the front guide sleeve, and the rear end face of the front guide sleeve rests on step surface one; the rear end face of the rear sealing sleeve is flush with the rear end face of the middle cylinder body, the front end face of the rear sealing sleeve is pressed together with the rear end face of the rear guide sleeve, and the front end face of the rear guide sleeve rests on step surface two.

[0024] According to the present invention, a step seal is further provided on the inner circumferential surface of the rear guide sleeve.

[0025] According to the present invention, the length of L on the rear guide sleeve is greater than the striking stroke of the piston.

[0026] According to the present invention, the material of the guide sleeve is 40CrNi2Mo.

[0027] According to the present invention, the front guide sleeve, the rear guide sleeve and the piston have a clearance fit, and the fitting clearance is 0.07mm-0.11mm; the front guide sleeve and the inner hole of the middle cylinder body have an interference fit, and the fitting size is 0.02mm-0.05mm; the front sealing sleeve, the rear guide sleeve and the rear sealing sleeve have a clearance fit with the inner hole of the middle cylinder body, and the fitting size is 0.02mm-0.03mm.

[0028] According to the present invention, the rear guide sleeve and the rear sealing sleeve are integrally formed.

[0029] (III) Beneficial effects

[0030] The beneficial effects of the present invention are as follows: the guide structure of the middle cylinder of a hydraulic breaker of the present invention, due to the setting of the front and rear guide sleeves, when the piston is subjected to radial force, the guide sleeve provides support for the centering movement of the piston, avoiding cylinder damage caused by direct contact between the piston and the inner hole of the middle cylinder body. When the guide sleeve is worn, it can be directly replaced at low cost. At the same time, the front and rear high-pressure oil lubrication system of the present invention plays an effective role in supporting, lubricating, cleaning, sealing and cooling the centering operation of the piston. The use of the present invention can greatly extend the service life of the middle cylinder body and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the middle cylinder component of the hydraulic breaker hammer of the present invention;

[0032] Figure 2 For the present invention Figure 1 The enlarged structural diagram of the middle C part;

[0033] Figure 3 For the present invention Figure 1 The enlarged structural diagram of the middle D part;

[0034] Figure 4 For the present invention Figure 1 A schematic diagram of the cross-sectional structure of the middle front guide sleeve;

[0035] Figure 5 For the present invention Figure 1 A schematic diagram of the cross-sectional structure of the middle and rear guide sleeve;

[0036] Figure 6 For the present invention Figure 1 A schematic diagram of the cross-sectional structure of the middle front sealing sleeve;

[0037] Figure 7 For the present invention Figure 1 Schematic diagram of the cross-sectional structure of the middle and rear sealing sleeve.

[0038] [Description of Reference Numerals]

[0039] 1: middle cylinder body; 11: oil return channel 1; 12: oil return channel 2; 13: step surface 1; 14: front chamber; 15: rear chamber; 16: step surface 2; 17: oil inlet channel; 18: oil return channel 3; 19: oil return channel 4; 2: piston; 3: front sealing sleeve; 31: dustproof sealing ring; 32: U-shaped sealing ring; 33: U-shaped sealing ring; 34: buffer sealing ring; 35: O-shaped sealing ring; 36: Oil return groove one; 37: Oil return hole one 4: Front guide sleeve; 41: Groove; 5: Rear guide sleeve; 51: O-type sealing ring; 52: O-type sealing ring; 53: Step seal; 54: Oil inlet hole; 55: Oil inlet groove; 56: Groove; 57: Oil return groove two; 58: Oil return channel five; 6: Rear sealing sleeve; 61: Groove; 62: O-type sealing ring; 63: U-type sealing ring; 64: Air seal. DETAILED DESCRIPTION

[0040] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0041] like Figure 1 As shown, in this embodiment, a middle cylinder guide structure of a hydraulic breaker is provided, including a middle cylinder body 1 and a piston 2. The inner circumference of the middle cylinder body 1 is provided with a front chamber 14 and a rear chamber 15. The middle cylinder body 1 is provided with a front sealing sleeve 3, a front guide sleeve 4, a rear sealing sleeve 6, a rear guide sleeve 5, a front high-pressure oil lubrication system and a rear high-pressure oil lubrication system. The front sealing sleeve 3, the front guide sleeve 4 and the front high-pressure oil lubrication system are arranged at the front end of the middle cylinder body 1, and the rear sealing sleeve 6, the rear guide sleeve 5 and the rear high-pressure oil lubrication system are arranged at the rear end of the middle cylinder body 1. The front guide sleeve 4 is interference fit with the inner hole of the middle cylinder body 1, and the matching size is 0.02mm-0.05mm; the front sealing sleeve 3, the rear guide sleeve 5, the rear sealing sleeve 6 and the inner hole of the middle cylinder body 1 are clearance fit, and the matching size is 0.02mm-0.03mm; the front guide sleeve 4, the rear guide sleeve 5 and the piston 2 are clearance fit, and the matching size is 0.07mm-0.11mm. The piston 2 is slidably arranged in the guide sleeve. The high-pressure oil lubrication system continuously supplies high-pressure oil to the space between the guide sleeve and the piston 2.

[0042] like Figures 1 to 3 As shown, the front high-pressure oil lubrication system includes an oil return channel 11, an oil return channel 2 12, an oil return groove 1 36, and an oil return hole 1 37, and the rear high-pressure oil lubrication system includes an oil inlet channel 17, an oil inlet hole 54, an oil inlet groove 55, an oil return groove 2 57, an oil return channel 58, an oil return channel 3 18, and an oil return channel 4 19.

[0043] like Figure 2 , Figure 3 and Figure 7As shown, the front sealing sleeve 3 is provided with an oil return groove 1 36 and an oil return hole 1 37; the rear guide sleeve 5 is provided with an oil inlet hole 54 and an oil return groove 2 57, the rear end surface of the rear guide sleeve 5 cooperates with the front end groove 61 of the rear sealing sleeve 6 to form an oil return passage 5 58, and the oil return groove 2 57 is connected to the oil return passage 5 58; the middle cylinder body 1 is provided with an oil inlet passage 17, an oil return passage 1 11, an oil return passage 2 12, an oil return passage 3 18 and an oil return passage 4 19; the oil return hole 1 37 is connected to the oil return passage 3 18 and the oil return passage 4 19 on the middle cylinder body, the oil inlet hole 54 is connected to the oil inlet passage 17 on the middle cylinder body, and the oil return passage 5 58 is connected to the oil return passage 3 18 and the oil return passage 4 19 on the middle cylinder body. The oil return passage 1 11, the oil return passage 2 12, the oil return passage 3 18 and the oil return passage 4 19 are connected to the main oil return passage on the middle cylinder body 1. During operation, the high-pressure oil in the front chamber 14 flows through the gap between the front guide sleeve 4 and the piston 2, through the oil return groove 1 36, into the oil return hole 1 37, and returns to the oil return channel 1 11 and the oil return channel 2 12 on the middle cylinder body; the oil inlet channel 17 at the rear end of the middle cylinder body continuously passes the high-pressure oil to the oil inlet hole 54, and the high-pressure oil flows through the gap between the rear guide sleeve 5 and the piston 2 through the oil inlet hole 54 and enters the oil return groove 2 57. The high-pressure oil in the oil return groove 2 57 flows back to the oil return channel 3 18 and the oil return channel 4 19 through the oil return channel 5 58. Through this structure, the flow lubrication of the hydraulic oil is realized.

[0044] like Figure 4-Figure 5 As shown, further, a plurality of grooves 41 are provided on the inner circumference of the front guide sleeve 4 for storing high-pressure oil. The inner circumference of the front guide sleeve 4 cooperates with the piston 2 to form a gap sealing section A, and a plurality of grooves 56 are provided on the inner circumference of the rear guide sleeve 5. The inner circumference of the rear guide sleeve 4 cooperates with the piston 2 to form a gap sealing section B, which is used to store high-pressure oil and form a high-pressure oil film, and maintain the high-pressure oil environment in the groove.

[0045] By sleeve-arranging and positioning the front guide sleeve 4 and the rear guide sleeve 5 on the inner circumference of the middle cylinder body 1, the piston 2 slides on the inner circumference of the guide sleeve, and the force-bearing area of ​​the piston 2 and the middle cylinder body 1 acts on the guide sleeve, avoiding direct contact between the piston 2 and the inner hole of the middle cylinder body 1. After the guide sleeve is worn, it can be removed and replaced. This structure effectively avoids the strain and wear of the piston 2 and the middle cylinder body 1, and prolongs the service life of the middle cylinder body 1. At the same time, the high-pressure oil lubrication system continuously provides high-pressure oil to the front guide sleeve 4 and the rear guide sleeve 5, so that the inner circumference of the front guide sleeve 4 and the rear guide sleeve 5 is always in the high-pressure oil working environment, and forms the gap sealing sections A and B for storing the high-pressure oil film. This flowing high-pressure oil provides good lubrication, support, sealing, cleaning and cooling for the operation of the piston 2 in the guide sleeve, avoiding the piston 2 from breaking through the high-pressure oil film and directly contacting the guide sleeve, and prolonging the service life of the guide sleeve.

[0046] like Figure 5-Figure 7As shown, further, a dustproof sealing ring 31, a U-shaped sealing ring 32, a U-shaped sealing ring 33, and a buffer sealing ring 34 are arranged on the inner circumference of the front sealing sleeve 3 in sequence from left to right, and an O-shaped sealing ring 35 is arranged on the outer circumference of the front sealing sleeve 3; a step seal 53 is arranged on the inner circumference of the rear guide sleeve 5, and an O-shaped sealing ring 51 and an O-shaped sealing ring 52 are arranged on the outer circumference in sequence from left to right; a U-shaped sealing ring 63 and an air seal 64 are arranged on the inner circumference of the rear sealing sleeve 6 in sequence from left to right, and an O-shaped sealing ring 62 is arranged on the outer circumference. The dustproof sealing ring is used to prevent external dust from entering the hydraulic cylinder; the U-shaped sealing ring seals the hydraulic oil to prevent the hydraulic oil from leaking out from the gap between the inner circumference of the guide sleeve and the piston; the buffer sealing ring is used to block the hydraulic oil from directly acting on the U-shaped sealing ring; the O-shaped sealing ring is used to prevent the hydraulic oil from leaking out from the gap between the outer circumference of the sealing sleeve and the inner hole of the middle cylinder body; the step seal is used to separate the rear chamber 15 and the gap sealing section B to prevent the high-pressure oil between the inner circumference of the rear guide sleeve 5 and the piston 2 from burdening the return oil of the rear chamber 15; the air seal 64 is used to seal the nitrogen in the nitrogen chamber in the rear cylinder body.

[0047] Specifically, the oil return groove 36 and the oil return hole 37 on the front sealing sleeve 3 are arranged on the right side of the sealing ring, and the oil inlet hole 54 on the rear guide sleeve 5 is arranged on the right side of the O-ring 51 and the step seal 53 and on the left side of the O-ring 52. When the piston 2 is in stroke, the high-pressure oil in the front chamber 14 will act on the buffer seal 34 and the U-shaped seal 33 through the gap between the inner circumference of the front guide sleeve 4 and the piston 2. The buffer seal 34 and the U-shaped seal 33 are easily broken and ineffective after being squeezed by the high-pressure oil for a long time. The oil return hole 37 and the oil return groove 36 are arranged on the right side of the sealing ring, so that the high-pressure oil in the front chamber 14 can directly flow back from the oil return groove 36 and the oil return hole 37 to the oil return channel 11 and the oil return channel 2 12 on the middle cylinder body 1, so as to prevent the high-pressure oil from continuing to flow forward and act on the sealing ring, thereby improving the service life of the sealing ring. Similarly, the oil return groove 2 57 and the oil return passage 5 58 on the rear guide sleeve 5 can also prevent a large amount of high-pressure oil from directly acting on the sealing ring on the rear sealing sleeve 6 and causing sealing failure.

[0048] In the present embodiment, the length of L on the rear guide sleeve 5 is set to be greater than the striking stroke of the piston 2 in the stroke stage, and the specific length of L is determined according to the actual specifications of the piston. This striking stroke refers to the distance from the piston touching the drill rod to the end of the stroke when the piston is in the stroke. The striking stroke of a general medium and large hydraulic breaker is 30mm-60mm. Extending the length of L can prevent the rear end of the piston 2 from contacting the gas seal on the rear sealing sleeve 6, and prevent the worn position of the piston 2 from contacting the gas seal 64 during the equipment storage and the return process of the piston 2, so that the gas seal 64 breaks and fails, causing nitrogen leakage in the nitrogen chamber. Of course, setting the length of L on the rear guide sleeve 5 to be less than or equal to the striking stroke of the piston 2 in the stroke stage does not affect the normal use of the breaker, but there is a possibility of gas seal 64 breaking and failing at this time, so this embodiment is a preferred implementation.

[0049] In this embodiment, the inner circumference of the middle cylinder body 1 is provided with a step surface 13 and a step surface 2 16. The front step end surface of the front sealing sleeve 3 is flush with the front end surface of the middle cylinder body 1, and the rear end surface of the front sealing sleeve 3 is pressed together with the front end surface of the front guide sleeve 4, and the rear end surface of the front guide sleeve 4 is against the step surface 13; the rear end surface of the rear sealing sleeve 6 is flush with the rear end surface of the middle cylinder body 1, and the rear end surface of the rear guide sleeve 5 is pressed together with the front end surface of the rear sealing sleeve 6, and the front end surface of the rear guide sleeve 5 is against the step surface 2 16. Through the cooperation of the step surface and the sealing sleeve, the guide sleeve is pressed and positioned to prevent the guide sleeve from moving forward and backward during the return stroke of the piston 2. Because the sealing sleeve and the guide sleeve are pressed and fixed on the middle cylinder body 1 by the cooperation of the step surfaces on the front cylinder body, the rear cylinder body and the middle cylinder body 1, when the guide sleeve is worn, the front sealing sleeve 3, the rear sealing sleeve 6 and the rear guide sleeve 5 can be removed without using special tools, and the guide sleeve 5 can be replaced after completion. The front guide sleeve 4 is interference fit with the inner hole of the middle cylinder body 1, and the front guide sleeve 4 can be knocked out or pressed out of the middle cylinder body 1 by using the piston 2 to hit or press the piston 2 with a press. The guide sleeve can be assembled and unassembled without opening a threaded hole on the guide sleeve, making the structure of the guide sleeve simpler and reducing the difficulty of processing the guide sleeve.

[0050] In this embodiment, by replacing the material of the guide sleeve with 40CrNi2Mo, the wear resistance of the guide sleeve is improved and the service life of the guide sleeve is extended. Of course, other materials can also be used to process the guide sleeve. At the same time, by reducing the structural size of the guide sleeve, the amount of material used is reduced and the production cost is reduced.

[0051] In the present embodiment, the rear guide sleeve 5 and the rear sealing sleeve 6 are formed separately. Of course, the rear guide sleeve 5 and the rear sealing sleeve 6 can also be formed as a whole, further reducing the difficulty of processing.

[0052] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A cylinder guide structure of a hydraulic breaker, comprising a cylinder body (1) and a piston (2), wherein the inner circumference of the cylinder body (1) is provided with a front chamber (14) and a rear chamber (15), characterized in that: The middle cylinder body is provided with a guide sleeve and a sealing sleeve, and the guide sleeve, the sealing sleeve and the middle cylinder body are equipped with an independent high-pressure oil lubrication system; The guide sleeve comprises a front guide sleeve (4) and a rear guide sleeve (5), and the sealing sleeve comprises a front sealing sleeve (3) and a rear sealing sleeve (6); The front guide sleeve (4) and the front sealing sleeve (3) are located at the front end of the middle cylinder body (1); The rear guide sleeve (5) and the rear sealing sleeve (6) are located at the rear end of the middle cylinder body (1); The guide sleeve and the piston (2) are clearance-matched, and the piston (2) slides back and forth in the guide sleeve; The high-pressure oil lubrication system comprises a front high-pressure oil lubrication system and a rear high-pressure oil lubrication system, wherein the high-pressure oil lubrication system continuously provides high-pressure oil to the gap between the inner circumferential surface of the guide sleeve and the piston (2); The front high-pressure oil lubrication system comprises an oil return passage 1 (11), an oil return passage 2 (12), an oil return hole 1 (37) and an oil return groove 1 (36); The rear high-pressure oil lubrication system comprises an oil inlet passage (17), an oil inlet hole (54), an oil inlet groove (55), a second oil return groove (57), a fifth oil return passage (58), a third oil return passage (18), and a fourth oil return passage (19); The oil return hole 1 (37) and the oil return groove 1 (36) are arranged on the front sealing sleeve (3); the oil inlet hole (54), the oil inlet groove (55) and the oil return groove 2 (57) are arranged on the rear guide sleeve (5); the rear guide sleeve (5) cooperates with the rear sealing sleeve (6) to form an oil return passage 5 (58); the oil inlet passage (17), the oil return passage 3 (18) and the oil return passage 4 (19) are arranged on the middle cylinder body (1); The oil return passage 1 (11) and the oil return passage 2 (12) are in communication with the oil return hole 1 (37); the oil inlet passage (17) is in communication with the oil inlet hole (54); the oil return passage 5 (58) is in communication with the oil return passage 3 (18) and the oil return passage 4 (19); The high-pressure oil in the front chamber (14) reaches the oil return groove 1 (36) through the gap between the inner circumference of the front guide sleeve (4) and the piston (2), and then flows back to the oil return passage 1 (11) and the oil return passage 2 (12) through the oil return hole 1 (37); the oil inlet passage (17) continuously passes the high-pressure oil to the oil inlet hole (54), and the high-pressure oil enters the gap between the inner circumference of the rear guide sleeve (5) and the piston (2) and reaches the oil return groove 2 (57), and then flows back to the oil return passage 3 (18) and the oil return passage 4 (19) through the oil return passage 5 (58); Sealing rings are provided on the inner circumferential surface and the outer circumferential surface of the front sealing sleeve (3).

2. A middle cylinder guide structure of a hydraulic breaker as described in claim 1, wherein the oil return hole 1 (37) is arranged on the right side of the sealing ring on the front sealing sleeve; the oil inlet hole (54) is arranged between the sealing rings on the rear guide sleeve (5); the front end surface of the rear sealing sleeve (6) is provided with a groove (61), and the rear end surface of the rear guide sleeve (5) cooperates with the groove (61) to form an oil return channel 5 (58).

3. A hydraulic breaker cylinder guide structure according to claim 1, wherein a plurality of grooves are further provided on the inner circumference of the guide sleeve, the inner circumference of the front guide sleeve (4) cooperates with the piston (2) to form a gap sealing section A, and the inner circumference of the rear guide sleeve (5) cooperates with the piston (2) to form a gap sealing section B.

4. A middle cylinder guide structure for a hydraulic breaker according to claim 1, wherein the inner circumferential surfaces of the front and rear ends of the middle cylinder body (1) are further provided with annular step surfaces; The front step end face of the front sealing sleeve (3) is flush with the front end face of the middle cylinder body (1), the rear end face of the front sealing sleeve (3) is pressed together with the front end face of the front guide sleeve (4), and the rear end face of the front guide sleeve (4) abuts against the step surface 1 (13); the rear end face of the rear sealing sleeve (6) is flush with the rear end face of the middle cylinder body (1), the front end face of the rear sealing sleeve (6) is pressed together with the rear end face of the rear guide sleeve (5), and the front end face of the rear guide sleeve (5) abuts against the step surface 2 (16).

5. The middle cylinder guide structure of a hydraulic breaker according to claim 3, wherein a step seal (53) is further provided on the inner circumferential surface of the rear guide sleeve (5).

6. The middle cylinder guide structure of a hydraulic breaker according to claim 1, wherein the guide sleeve is made of 40CrNi2Mo.

7. A middle cylinder guide structure of a hydraulic breaker as claimed in claim 1, wherein the front guide sleeve (4) and the rear guide sleeve (5) are clearance-matched with the piston (2), and the clearance is 0.07mm-0.11mm; the front guide sleeve (4) is interference-fitted with the inner hole of the middle cylinder body (1), and the fitting size is 0.02mm-0.05mm; the front sealing sleeve (3), the rear guide sleeve (5), and the rear sealing sleeve (6) are clearance-matched with the inner hole of the middle cylinder body (1), and the fitting size is 0.02mm-0.03mm.

8. The middle cylinder guide structure of a hydraulic breaker according to claim 7, wherein the rear guide sleeve (5) and the rear sealing sleeve (6) are integrally formed.

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