Sealing structure for improving pressure bearing capacity of main drive of shield tunneling machine

Abstract

The utility model provides a sealing structure for improving the pressure bearing capacity of a main drive of a shield tunneling machine. The sealing structure comprises an outer sealing assembly located between the main bearing and the shield body and an inner sealing assembly located between the cutterhead and the main bearing, and the inner sealing assembly is arranged in an inner sealing cavity between the main bearing and the cutterhead transfer ring and comprises an inner sealing pressing ring and two second lip-shaped sealing rings which are sequentially arranged inwards from the cutting face of the cutterhead. A second isolating ring is arranged between the two second lip-shaped sealing rings, sealing lips of the two second lip-shaped sealing rings face inwards, an inner grease sealing cavity is formed between the two second lip-shaped sealing rings and the second isolating ring, and a grease channel leading to the inner grease sealing cavity is formed in the cutter head transmission part. By improving the structure of the main drive inner seal and optimizing and upgrading the structure, the maximum pressure bearing capacity of a main drive sealing system of the shield tunneling machine is improved, all sealing pressures are visual and controllable, and the process risk control capacity is effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the seal of shield machine main drive, concretely is a kind of seal structure of improving the pressure-bearing capacity of shield machine main drive. BACKGROUND

[0002] Shield machine is the core of modern tunnel construction, and the main drive system of shield machine is the core component of shield machine, which is responsible for transmitting power to the cutterhead and driving it to rotate for tunneling. The main drive gear box is filled with gear oil. In the face of complex geological conditions such as soil, sandstone, groundwater, etc., once the geological impurities invade the main drive system, it will seriously threaten its normal operation, and even cause damage, affecting construction efficiency and safety. In order to ensure the sealing of the main drive, three seals will be provided for the main drive system, including outer seal, main drive inner seal and reducer motor seal. With the development of the times and the improvement of shield construction technology, the shield construction environment is becoming more and more complex, such as high water pressure, high abrasion resistance, high hardness rock, etc. These environments put higher requirements on the sealing system; in extreme working conditions, the sealing system is prone to failure, and it is crucial to study how to improve its performance.

[0003] In the existing main drive sealing system, the outer seal is installed on the outermost side of the main drive system, near the cutterhead side of the shield machine, and usually adopts a multi-chamber design. Its main function is to prevent external mud, sludge and other substances from entering the main drive system and to withstand the high pressure and pollutants on the cutterhead side. The conventional measure is to prevent through the multi-chamber sealing system. The outer seal of the main drive of the shield machine is a multi-seal system, with a total of four lip-shaped sealing devices from the outside to the inside, of which three sealing lips are outward, and one sealing lip is inward, separating four chambers. According to functionality, they are divided into lubrication chamber, sealing chamber, buffer chamber and leakage chamber in turn. The first two sealing chambers 5 and 6 are injected with black grease or yellow grease, which is the main body of the seal. The third chamber 7 is injected with oil and gas mixture, which is pressurized according to needs, providing back pressure for the first two sealing systems to balance the pressure of the excavation chamber. The fourth sealing chamber, leakage chamber 8, is mainly used to collect leaked media, protect the environment and provide fault warning.

[0004] The inner seal of the main drive is installed on the inner side of the main drive system, close to the side of the gear box, and mainly functions to prevent lubricating oil in the gear box from leaking and to block external contaminants from entering the gear box. The working environment and sealing protection measures of this area are relatively good compared to the outer seal, and the probability of failure of the sealing position is low. The conventional preventive measures are two oppositely installed lip seals (with an isolation ring installed in the middle) used to resist the water and soil pressure in the soil bin and the gear oil pressure in the speed reducer; one side of the oppositely installed lip seal receives the water and soil pressure in the soil bin, and the other side receives the internal pressure bearing capacity of the main drive. However, in actual construction, the pressure value on one side of the main drive gear box is much greater than that on the other side, and this method cannot guarantee the pressure on one side of the main drive gear box. The reducer seal of the main drive is installed at the reducer part of the main drive system. The main function is to prevent the lubricating oil in the reducer from leaking and external contaminants from entering the reducer. The sealing of this area has lower pressure requirements than the inner and outer seals, generally not exceeding 5 bar.

[0005] In actual construction, the outer seal of the main drive is prone to failure, which causes water and soil and other impurities in the soil bin to enter the main drive gear box through the outer seal passage, resulting in equipment damage. Moreover, the failure of the main drive seal will result in insufficient drive pressure bearing capacity, low safety factor and other technical problems, especially for long-distance crossing of high water and soil pressure strata by a shield machine, the insufficient drive pressure bearing capacity poses a high safety risk. Therefore, the failure of the main drive seal is a serious problem, which not only affects the construction progress, but also may cause equipment damage. Since the main drive seal is located in the core part of the shield machine, it is difficult to replace, and the traditional replacement method requires shutdown, excavation of the working well, long construction period and high cost; especially in water-rich strata or soft soil environment, the cost of excavating the working well for maintenance is high, the risk is great, and it may affect the safety of surrounding buildings. Practical new type content

[0006] In view of the problem of insufficient main drive pressure bearing capacity caused by the easy failure of the main drive seal in the prior art, the utility model provides a sealing structure for improving the main drive pressure bearing capacity of a shield machine, which improves the maximum pressure bearing capacity of the main drive sealing system of the shield machine by improving the inner seal structure in the main drive sealing structure, and effectively improves the process risk control ability.

[0007] In order to achieve the above technical purpose, the utility model provides a kind of sealing structure for improving the pressure capacity of shield machine main drive, including the outer sealing assembly between main bearing and shield and the inner sealing assembly between cutterhead and main bearing, the inner sealing assembly is arranged in the inner sealing cavity between main bearing and cutterhead transmission ring, including the inner sealing compression ring and two second lip-shaped sealing rings that are sequentially arranged from cutterhead cutting surface inward, second isolation ring is equipped between two second lip-shaped sealing rings, the sealing lip of two second lip-shaped sealing rings is all inward, and inner grease sealing cavity is equipped between two second lip-shaped sealing rings and second isolation ring, grease passage leading to inner grease sealing cavity is set in cutterhead transmission.

[0008] Further technical solutions of the utility model: the sealing structure further includes manual pressurization control system, and the manual pressurization system includes electric grease pump, the electric grease pump is communicated with grease passage by oil injection pipe, and grease distribution valve is equipped on oil injection pipe.

[0009] Further technical solutions of the utility model: the sealing structure further includes gear box oil-gas pressurization system, and the gear box oil-gas pressurization system includes sealed oil-gas tank, pressure stabilizing system and oil pump, the pressure stabilizing system is communicated with the air inlet of oil-gas tank, inlet ball valve is equipped on connecting pipeline, the oil pump is communicated with the oil inlet of oil-gas tank by oil inlet pipe, and oil inlet ball valve is equipped on oil inlet pipe;The oil-gas outlet of oil-gas tank is communicated with the main bearing oil port at the top of shield main drive by oil-gas pipeline, and control ball valve is equipped on oil-gas pipeline.

[0010] Further technical solutions of the utility model: the outer sealing assembly is arranged in the outer sealing cavity between main bearing and shield, including the outer sealing compression ring and four first lip-shaped sealing rings that are sequentially arranged from cutterhead cutting surface inward, first isolation ring is equipped between two adjacent first lip-shaped sealing rings, wherein the sealing lip of three first lip-shaped sealing rings on the outside is outward, the sealing lip of the first lip-shaped sealing ring on the most inside is inward, and four first lip-shaped sealing rings sequentially separate first grease sealing cavity, second grease sealing cavity, third grease sealing cavity and fourth grease sealing cavity from outside to inside in outer sealing cavity.

[0011] The preferred technical solutions of the utility model: the inner sealing compression ring is assembled by six arc-shaped compression ring pieces, the section of each arc-shaped compression ring piece is L-shaped, bolt hole is equipped on the ring surface of each arc-shaped compression ring piece, the arc-shaped compression ring piece is pressed on the outside of inner sealing assembly, and is fixed and pressed by bolt.

[0012] The preferred technical solutions of the utility model: the second isolation ring is spliced by six arc-shaped isolation ring pieces, both ends of each arc-shaped isolation ring piece are provided with mutually matched splicing interfaces, and the splicing interfaces of adjacent two arc-shaped isolation ring pieces are spliced and fixed by bolt after splicing;Two hoisting holes are equipped on each arc-shaped isolation ring piece.

[0013] The second lip-shaped sealing ring of the second isolation ring is provided with a convex part at one end of the inner side, and after the second isolation ring is fixed, the convex part is embedded in the recess of the inner side second lip-shaped sealing ring.

[0014] The gear box oil gas pressurization system further comprises a transparent observation tube withstanding 10 bar pressure, one end of the transparent observation tube is in communication with the top of the fourth grease sealing cavity, and the other end is in communication with the bottom of the fourth grease sealing cavity.

[0015] (1) The utility model discloses an improved inner sealing structure in the main drive sealing structure, customizes the inner sealing compression ring and the isolation ring, and also installs the inner side lip-shaped sealing of the inner sealing in the inward form, at this time, the two inner sealings are changed into the lip mouth all towards the installation in the gearbox, and the grease injection cavity is additionally arranged, which further increases the internal pressure-bearing capacity of the gearbox and also increases a barrier to isolate the natural environment in the soil bin.

[0016] (2) The utility model discloses that the main drive inner butter cavity increases the manual pressurization control system, specifically increases electric butter pump and butter distribution valve and other components, carries out manual pressurization control to the main drive inner butter cavity, and the comprehensive pressure-bearing capacity of the inner sealing is improved by 200% after transformation.

[0017] (3) The diameter of the new isolation ring in the utility model is consistent with the model of the shield tunneling machine and the size demand of the cutter head, for the convenience of transportation and installation, the isolation ring is divided into six subrings, the lifting hole and the bolt hole are arranged on each subring, the horizontal and vertical transportation of the subrings can be completed through the reserved lifting hole, and then the subblocks are sequentially installed into a circle, and then are fastened through the reserved bolt hole, so that the compression ring is installed.

[0018] (4) The utility model discloses a gear box oil gas pressurization system, the top main bearing oil port of the main drive is used to pressurize the reduction gearbox (the oil gas sealing tank is pressurized through the stable pressure system of the oil gas sealing tank, and the gear oil in the oil gas sealing tank is pressurized to the main drive gear), the pressure of the gearbox is controlled to be equal to or slightly greater than the pressure of the soil bin. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the structural schematic diagram of the utility model;

[0020] Figure 2 It isFigure 1 A part of the enlarged schematic view of the middle;

[0021] Figure 3 The structure schematic view of the outer sealing assembly in the utility model;

[0022] Figure 4 The structure schematic view of the inner sealing assembly in the utility model;

[0023] Figure 5 The structure schematic view of the manual pressure control system in the utility model;

[0024] Figure 6 The overall structure schematic view of the inner sealing pressure ring in the utility model;

[0025] Figure 7 The overall structure schematic view of the arc-shaped pressure ring piece in the utility model;

[0026] Figure 8 The cross-sectional schematic view of the arc-shaped pressure ring piece in the utility model;

[0027] Figure 9 The overall structure schematic view of the second isolation ring in the utility model;

[0028] Figure 10 The front structure schematic view of the arc-shaped isolation ring piece in the utility model;

[0029] Figure 11 The side structure schematic view of the arc-shaped isolation ring piece in the utility model;

[0030] Figure 12 The cross-sectional schematic view of the arc-shaped isolation ring piece in the utility model;

[0031] Figure 13 The structure schematic view of the gear box oil gas pressure system in the utility model.

[0032] In the figure: 1 - shield machine main drive gear box, 2 - outer sealing assembly, 200 - first lip-shaped sealing ring, 201 - first isolation ring, 202 - outer sealing pressure ring, 203 - first grease sealing cavity, 204 - second grease sealing cavity, 205 - third grease sealing cavity, 206 - fourth grease sealing cavity, 3 - inner sealing assembly, 300 - inner sealing pressure ring, 3001 - arc-shaped pressure ring piece, 3002 - bolt hole, 301 - second lip-shaped sealing ring, 302

[0033] —Second isolation ring, 3021—Arc-shaped isolation ring piece, 3022—Assembly joint, 3023—Lifting hole, 3024—Protrusion, 303—Inner grease sealing cavity, 4—Reducer sealing assembly, 5—Main bearing, 6—Shield body, 7—Cutter disc, 8—Cutter disc transfer ring, 9—Grease channel, 10—Electric grease pump, 11—Oil injection pipe, 12—Grease distribution valve, 13—Oil and gas tank, 14—Pressure stabilizing system, 15—Oil pump, 16—Inlet ball valve, 17—Oil inlet ball valve, 18—Main bearing oil port, 19—Control ball valve, 20—Transparent observation tube. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 12 All accompanying drawings are simplified versions of embodiments and are intended solely for the purpose of clearly and concisely illustrating the embodiments of this utility model. The technical solutions shown in the drawings below are specific solutions of embodiments of this utility model and are not intended to limit the scope of the claimed utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0035] In the description of this utility model, it should be understood that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] The embodiment provides a sealing structure to improve the pressure-bearing capacity of the main drive of a tunnel boring machine, such as... Figures 1 to 5As shown, including manual pressure control system, shield machine main drive gear box 1, located between the main bearing 5 and shield body 6 outer sealing assembly 2, located between the cutterhead 7 and the main bearing 5 inner sealing assembly 3 and reducer sealing assembly 4, the outer sealing assembly 2 is arranged in the outer sealing cavity between the main bearing 5 and the shield body 6, including the outer sealing ring 202 and four first lip-shaped sealing ring 200 arranged inwards from the cutterhead cutting surface, the first isolation ring 201 is arranged between the adjacent two first lip-shaped sealing ring 200, wherein the sealing lip of the outer three first lip-shaped sealing ring 200 faces outward, the sealing lip of the innermost first lip-shaped sealing ring 200 faces inward, the four first lip-shaped sealing ring 200 separates the outer sealing cavity from outside to inside, and the first grease sealing cavity 203, the second grease sealing cavity 204, the third grease sealing cavity 205 and the fourth grease sealing cavity 206 are sequentially separated; The inner sealing assembly 3 is arranged in the inner sealing cavity between the main bearing 5 and the cutterhead transmission ring 8, including the inner sealing ring 300 and two second lip-shaped sealing ring 301 arranged inwards from the cutterhead cutting surface, the second isolation ring 302 is arranged between the two second lip-shaped sealing ring 301, the sealing lip of the two second lip-shaped sealing ring 301 faces inward, and the inner grease sealing cavity 303 is arranged between the two second lip-shaped sealing ring 301 and the second isolation ring 302, the grease channel 9 is opened on the cutterhead transmission ring 8 to the inner grease sealing cavity 303, the manual pressure system includes electric grease pump 10, the electric grease pump 10 is communicated with the grease channel 9 through the oil injection pipe 11, and the grease distribution valve 12 is arranged on the oil injection pipe 11. Manual pressure control is carried out on the main drive inner grease cavity, so that the comprehensive pressure bearing capacity of the inner sealing assembly is improved by 200%.

[0037] In the embodiment, as Figure 13As shown in the figure, the gearbox oil gas pressurization system comprises a sealed oil gas tank 13, a pressure stabilizing system 14 in communication with the air inlet of the oil gas tank 13, an air inlet ball valve 16 provided on the connecting pipeline, and an oil pump 15 in communication with the oil inlet of the oil gas tank 13 through an oil inlet pipeline and provided with an oil inlet ball valve 17 on the oil inlet pipeline. The oil gas outlet of the oil gas tank 13 is in communication with the main bearing oil inlet 18 at the top of the main drive of the shield through an oil gas pipeline, and a control ball valve 19 is provided on the oil gas pipeline. A new set of gearbox oil gas pressurization system is added to pressurize the reduction gearbox through the main bearing oil inlet at the top of the main drive (the oil gas tank is pressurized by adjusting the pressure stabilizing system of the oil gas tank, and the gearbox oil in the oil gas tank is pressurized to the main drive gearbox), and the pressure of the gearbox is controlled to be equal to or slightly greater than the soil chamber pressure. The specific implementation principle is: first estimate the pressure N of the gearbox oil tank to be increased by experience method, estimate the volume of the gearbox as 0.7 cubic meters according to the amount of gearbox oil used for daily full oil filling of the main drive gearbox, and calculate the compression amount of the gearbox oil according to the formula: volume change (compression amount) = compression coefficient * initial volume of gearbox oil * pressure change. During the pressurization process of the oil gas pressurization system to the gearbox oil, the liquid level in the oil gas tank is observed, and the air inlet pressure of the oil gas tank is adjusted. If the liquid level in the oil gas tank is decreasing during the pressurization process, the air inlet pressure of the oil gas pressurization system is adjusted through the pressure reducing valve until the liquid level in the oil gas tank is stable, and the pressure of the gearbox oil tank is built at this time.

[0038] In the embodiment, the reducer sealing assembly 4 adopts high-pressure sealing elements with a pressure bearing capacity of ≥10 bar, which can be used only after passing the high-pressure test, thereby improving the pressure bearing capacity of the output end of the reducer.

[0039] In the embodiment, as shown in the figure, Figures 6 to 8 As shown in the figure, the inner sealing compression ring 300 is assembled by six arc-shaped compression ring pieces 3001, each of which has an L-shaped cross section, and bolt holes 3002 are provided on the ring surface of each arc-shaped compression ring piece 3001. The arc-shaped compression ring pieces 3001 are pressed on the outer side of the inner sealing assembly 3 and are fixed and compressed by bolts. The diameter of the inner sealing compression ring 300 is consistent with the model of the shield machine and the size requirement of the cutter head. In order to facilitate transportation and installation, the six arc-shaped compression ring pieces 3001 are sequentially installed in a circle, and then fastened through the reserved bolt holes 3002 to complete the installation of the compression ring. As shown in the figure, Figures 9 to 12As shown, the second isolation ring 302 is spliced by six arc-shaped isolation ring pieces 3021, each of which is provided with a matching splicing port 3022 at both ends, and the splicing ports 3022 of the adjacent two arc-shaped isolation ring pieces 3021 are spliced and fixed by bolts; two lifting holes 3023 are arranged on each arc-shaped isolation ring piece 3021; the second isolation ring 302 is provided with a convex portion 3024 near one end of the second lip-shaped sealing ring 301 on the inner side, and after the second isolation ring 302 is fixed, the convex portion 3024 is embedded in the recess of the second lip-shaped sealing ring 301 on the inner side. The diameter of the second isolation ring 302 is consistent with the model of the shield tunneling machine and the size requirement of the cutter head, and for the convenience of transportation and installation, the horizontal and vertical transportation of the arc-shaped isolation ring pieces 3021 can be completed through the reserved lifting holes 3023. Before installation, the arc-shaped isolation ring pieces 3021 are fixed into a circle by bolts and reserved splicing ports, and then embedded in the recess of the inner lip-shaped sealing, and then the outer lip-shaped sealing is installed to complete the inner sealing installation.

[0040] In the embodiment, the gear box oil and gas pressurizing system further comprises a transparent observation tube 20 withstanding 10 bar pressure, one end of the transparent observation tube 20 being in communication with the top of the fourth grease sealing cavity 206, and the other end being in communication with the bottom of the fourth grease sealing cavity 206; the transparent observation tube 20 is used for monitoring whether the sand enters the main drive outer sealing system.

[0041] The specific steps of sealing using the sealing structure for improving the pressure-bearing capacity of the main drive of the shield tunneling machine in the embodiment are as follows:

[0042] S1. The outer sealing assembly between the main bearing and the shield body, the inner sealing assembly between the cutter head and the main bearing, and the reducer sealing assembly of the main drive of the shield tunneling machine are installed; the sealing lips of the second lip-shaped sealing rings of the inner sealing assembly are all directed towards the inside of the gearbox;

[0043] S2. Black grease is injected into the first grease sealing cavity 203 of the outer sealing assembly 3, and the injection pressure is increased by 20% to 30% of the original injection pressure; yellow grease is injected into the second grease sealing cavity 204 of the outer sealing assembly, and the injection pressure is increased by 20% to 30% of the original injection pressure; yellow grease is injected into the third grease sealing cavity 205 and the fourth grease sealing cavity 206 of the outer sealing assembly, respectively;

[0044] S3. Yellow grease is injected into the inner grease sealing cavity 303 of the inner sealing assembly 2 through the grease channel 9 on the cutter head transmission ring 8 at the same time.

[0045] S4. The gear box oil gas pressurization system is used to inject oil gas to the top main bearing oil port of the shield main drive, the pressure of the oil gas tank is adjusted by the pressure stabilizing system of the gear box oil gas pressurization system, the gear oil in the oil gas tank is pressurized to the main drive gear reduction box, and the pressure of the main drive gear reduction box is controlled to be slightly greater than the soil chamber pressure, generally 1.0-1.2 times of the soil chamber pressure.

[0046] The above is only one embodiment of the present application, which is described in more detail, but it should not be construed as limiting the scope of the present application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A sealing structure for improving the pressure-bearing capacity of a main drive of a shield tunneling machine, comprising an outer sealing assembly (2) located between a main bearing (5) and a shield body (6) and an inner sealing assembly (3) located between a cutter head (7) and the main bearing (5), characterized in that: The inner sealing assembly (3) is arranged in an inner sealing cavity between the main bearing (5) and the cutter disc transmission ring (8), and comprises, from the cutter disc cutting surface inwards, an inner sealing compression ring (300) and two second lip-shaped sealing rings (301), a second isolation ring (302) is arranged between the two second lip-shaped sealing rings (301), the sealing lips of the two second lip-shaped sealing rings (301) are both inward, an inner grease sealing cavity (303) is arranged between the two second lip-shaped sealing rings (301) and the second isolation ring (302), and a grease passage (9) is formed in the cutter disc transmission ring (8) and leads to the inner grease sealing cavity (303).

2. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1, characterized in that: The sealing structure further comprises a manual pressure control system, the manual pressure control system comprises an electric grease pump (10), the electric grease pump (10) is communicated with the grease passage (9) through an oil injection pipe (11), and a grease distribution valve (12) is arranged on the oil injection pipe (11).

3. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1 or 2, characterized in that: The sealing structure further comprises a gear box oil-gas pressure system, the gear box oil-gas pressure system comprises a sealed oil-gas tank (13), a pressure stabilizing system (14) and an oil pump (15), the pressure stabilizing system (14) is communicated with an air inlet of the oil-gas tank (13), an air inlet ball valve (16) is arranged on a connecting pipeline, the oil pump (15) is communicated with an oil inlet of the oil-gas tank (13) through an oil inlet pipe, and an oil inlet ball valve (17) is arranged on the oil inlet pipe; an oil-gas outlet of the oil-gas tank (13) is communicated with a main bearing oil port (18) at the top of a shield main drive through an oil-gas pipeline, and a control ball valve (19) is arranged on the oil-gas pipeline.

4. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1 or 2, characterized in that: The outer sealing assembly (2) is arranged in an outer sealing cavity between the main bearing (5) and the shield body (6), and comprises, from the cutter disc cutting surface inwards, an outer sealing compression ring (202) and four first lip-shaped sealing rings (200), a first isolation ring (201) is arranged between every two adjacent first lip-shaped sealing rings (200), wherein the sealing lips of the outer three first lip-shaped sealing rings (200) are outward, the sealing lip of the innermost first lip-shaped sealing ring (200) is inward, and the four first lip-shaped sealing rings (200) sequentially divide the outer sealing cavity into a first grease sealing cavity (203), a second grease sealing cavity (204), a third grease sealing cavity (205) and a fourth grease sealing cavity (206) from outside to inside.

5. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1 or 2, characterized in that: The inner sealing compression ring (300) is assembled by six arc-shaped compression ring pieces (3001), the cross section of each arc-shaped compression ring piece (3001) is L-shaped, bolt holes (3002) are arranged on the ring surface of each arc-shaped compression ring piece (3001), the arc-shaped compression ring pieces (3001) are pressed on the outer side of the inner sealing assembly (3) and are fixed and compressed by bolts.

6. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1 or 2, characterized in that: The second isolation ring (302) is assembled by six arc-shaped isolation ring pieces (3021), the two ends of each arc-shaped isolation ring piece (3021) are provided with matching splicing interfaces (3022), and the splicing interfaces (3022) of the adjacent two arc-shaped isolation ring pieces (3021) are spliced and fixed by bolts; two hoisting holes (3023) are arranged on each arc-shaped isolation ring piece (3021).

7. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 1 or 2, characterized in that: The second isolation ring (302) is provided with a convex part (3024) near one end of the second lip-shaped sealing ring (301) on the inner side, and after the second isolation ring (302) is fixed, the convex part (3024) is embedded in the recess of the second lip-shaped sealing ring (301) on the inner side.

8. The sealing structure for improving the pressure-bearing capacity of the main drive of a tunneling machine according to claim 3, characterized in that: The gear box oil gas pressurizing system further comprises a transparent observation tube (20) bearing a pressure of 10 bar, one end of the transparent observation tube (20) being in communication with the top of the fourth grease sealing cavity (206), and the other end being in communication with the bottom of the fourth grease sealing cavity (206); the transparent observation tube (20) is used for monitoring whether the sand enters the main drive outer sealing system.

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