Flange end sealing structure of front output shaft of transfer case

Abstract

The utility model discloses a flange end sealing structure of a front output shaft of a transfer case, which can effectively play roles in sealing oil inside, sealing oil on a joint part and preventing dust and water outside, improves the structural form of a gap between a transmission casing and a front output flange, improves the difficulty of entering of sand dust and muddy water, and improves the reliability of the transmission casing and the front output flange. And a targeted side protection structure is arranged on the oil seal, so that the service life of the oil seal can be effectively guaranteed. The front output flange is provided with a first ring neck and a second ring neck which are coaxially arranged, an oil seal space is formed between the first ring neck and the hole wall of the front output hole, a shrinkage space is formed between the second ring neck and the hole wall of the front output hole, the end, away from the shrinkage space, of the oil seal space is covered with a dust cover, and a bidirectional oil seal is located in the oil seal space. The two-way oil seal comprises an oil seal base body, an inner oil seal lip and an outer waterproof lip, a side waterproof lip is arranged on the oil seal base body, and the distance between the side waterproof lip and the first ring neck is gradually increased in the direction from the position close to the oil seal base body to the position away from the oil seal base body.

Description

Technical Field

[0001] This utility model belongs to the technical field of vehicle transmission, transfer case, shaft end seal, and flange end seal, and particularly relates to a flange end seal structure for the front output shaft of a transfer case. Background Technology

[0002] The front output shaft of a car transfer case is usually located at a lower position on the chassis (while the input shaft, rear output shaft, etc., are relatively higher), and the outer end (front end) of the front output shaft faces the front of the car. Cars with transfer cases often travel on unpaved roads, encountering a lot of sand and mud. Therefore, the area at the front end of the front output shaft needs special attention to protect against sand and mud. If the oil seal in this area is not adequately protected or fails prematurely (before its replacement cycle), it can lead to a series of problems such as oil leakage, oil emulsification, and abnormal wear of the transmission structure.

[0003] In the existing technology, the external dust cover can play a certain role in preventing sand and mud. However, as more and more sand and mud enter the interior through the gap between the dust cover and the transmission housing (main housing) (referring to the interior of the gap between the transmission housing and the front output flange), along with factors such as vehicle acceleration and deceleration and vibration, it will quickly damage the key sealing parts of the oil seal, affecting the service life of the oil seal and causing it to fail prematurely.

[0004] It should be noted that there is relative rotation between the dust cover and the transmission housing (main housing). Considering cost, it is impossible to achieve an absolute seal. A small amount of sand, mud, water, etc. will still enter the gap between the transmission housing and the front output flange and come into contact with the oil seal. Utility Model Content

[0005] This utility model provides a sealing structure for the front output shaft flange end of a transfer case, which can effectively seal the oil internally, seal the joint, and prevent dust and water from entering. It improves the structural form of the gap between the transmission housing and the front output flange, making it more difficult for sand and mud to enter. In addition, a targeted side protection structure is set on the oil seal, which can effectively ensure the service life of the oil seal.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A front output shaft flange end sealing structure for a transfer case includes a main housing, a front output flange, and a front output shaft. The main housing has a front output hole, one end of the front output flange is located inside the front output hole, a bidirectional oil seal is fitted over the front output flange and located inside the front output hole, a dust cover is fixed to the front output flange, a shaft hole is provided on the front output flange, the front output shaft passes through the shaft hole and is fixed to the front output flange, and the front output shaft and the shaft hole are sealed by an inner sealing ring of the flange.

[0008] The front output flange has a first ring neck and a second ring neck arranged coaxially. The outer diameter of the second ring neck is larger than that of the first ring neck. The end face of the second ring neck facing the first ring neck is the inner sealing ring face. An oil seal space is formed between the first ring neck and the wall of the front output hole. A narrowing space is formed between the second ring neck and the wall of the front output hole. The end of the oil seal space away from the narrowing space is covered by a dust cover.

[0009] The bidirectional oil seal is located within the oil seal space. The bidirectional oil seal includes an oil seal base that is sealed and fixed to the wall of the front output hole, an inner sealing lip that rotates and seals with the front output shaft, and an outer waterproof lip that rotates and seals with the front output shaft. The oil seal base is provided with a side waterproof lip that rotates and seals with the inner sealing ring surface. The distance between the side waterproof lip and the first ring neck gradually increases from the direction adjacent to the oil seal base to the direction away from the oil seal base.

[0010] Preferably, the front output hole includes an inner output section and an outer output section, the oil seal base is sealed and fixed to the inner output section hole wall, and the inner diameter of the outer output section, the outer diameter of the second journal, the inner diameter of the inner output section and the outer diameter of the first journal decrease in sequence.

[0011] Preferably, the front output flange has a third journal and a fourth conical journal outside the front output hole. The minimum outer diameter of the fourth conical journal is greater than the outer diameter of the third ring journal. The end face of the fourth conical journal facing the third ring journal is the outer positioning ring face. The dust cover includes an inner cylinder cover, a ring plate cover and an outer cylinder cover arranged coaxially. The outer end of the inner cylinder cover is connected to the inner edge of the ring plate cover, and the outer end of the outer cylinder cover is connected to the outer edge of the ring plate cover. The inner side wall of the inner cylinder cover is in contact with the outer side wall of the third ring journal, and the outer end of the ring plate is in contact with the outer positioning ring face. The main housing is provided with a limiting ring groove with an opening facing the fourth conical journal, and the inner end of the outer cylinder cover is located in the limiting ring groove.

[0012] Preferably, the inner sealing ring surface is provided with an inwardly tapered flange ring protruding toward the oil seal substrate. The inner diameter of the inwardly tapered flange ring is larger than the maximum outer diameter of the side waterproof lip, and there is a margin gap between the inwardly tapered flange ring and the side waterproof lip.

[0013] Preferably, the oil seal base is provided with a metal skeleton plate, which includes a vertical ring plate and a horizontal cylindrical plate. The outer edge of the vertical ring plate is coaxially fixed with one end of the horizontal cylindrical plate. The oil seal base is provided with a metal retaining ring for pressing the inner sealing lip. The metal retaining ring is sleeved on the outside of the inner sealing lip. The oil seal base is provided with an intermediate lip located between the inner sealing lip and the outer waterproof lip. The intermediate lip is rotatably sealed with the front output shaft.

[0014] Preferably, the outer end of the shaft hole opens into the inner end face of the front output flange, and the front output shaft is provided with a front shaft head section located inside the front output flange. The diameter of the front shaft head section is smaller than the diameter of the front output shaft. An inner flange sealing ring is fitted on the front shaft head section. The inner flange sealing ring includes a high ring inner ring that contacts the outer wall of the front shaft head section and a flat ring outer ring that contacts the wall of the front shaft hole. The flat ring outer ring is fitted outside the high ring inner ring.

[0015] On the axial direction of the front output shaft: the length of the inner ring of the high ring is greater than the length of the outer ring of the flat ring. One end of the inner ring of the high ring, one end of the front shaft hole, the other end of the inner ring of the high ring and the front output shaft are arranged in sequence. The inner end face of the front output flange, the outer ring of the flat ring and the front output shaft are arranged in sequence.

[0016] The front axle head section is fitted with a gasket for pressing the inner ring of the high ring and can be attached to the inner end face of the front output flange. The front axle head section is also equipped with a lock nut for pressing the gasket, and the lock nut is threadedly engaged with the front axle head section.

[0017] The beneficial effects of this utility model are: it can effectively seal the oil inside and at the joints, and provide dust and water protection to the outside; it improves the structural form of the gap between the gearbox housing and the front output flange, increasing the difficulty for sand and mud to enter; and it has a targeted side protection structure on the oil seal, which can effectively ensure the service life of the oil seal; it improves the fitting method between the dust cover and the main housing, which can prevent the outer cylinder cover from becoming loose between the outer cylinder cover and the main housing, thereby ensuring the protective effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0020] Figure 3 yes Figure 1 Enlarged view of point B in the middle;

[0021] Figure 4 This is a partial structural diagram of the bidirectional oil seal of this utility model;

[0022] Figure 5 This is a partial structural schematic diagram of the present invention.

[0023] Reference numerals: Main housing 1, front output hole 1.1, limiting ring groove 1.2, front output flange 2, inner end face 2a, first ring neck 201, oil seal space 201.1, second ring neck 202, inner sealing ring surface 202a, narrowing space 202.1, third journal 203, fourth tapered neck 204, inner flange ring 205, front output shaft 3, front shaft head section 301, gasket 302, lock nut 303, dust cover 4, inner cylinder cover 401, ring plate cover 402, outer cylinder cover 403, flange inner sealing ring 5, high ring inner ring 501, flat ring outer ring 502, oil seal base 601, metal retaining ring 601.1, inner sealing lip 602, outer waterproof lip 603, side waterproof lip 604, metal skeleton piece 605, vertical ring piece 605.1, horizontal cylinder piece 605.2, intermediate lip 606. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0025] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown,

[0026] A flange end sealing structure for the front output shaft 3 of a transfer case is disclosed. The transfer case includes a main housing 1, a front output flange 2, and a front output shaft 3. The main housing 1 is provided with a front output hole 1.1. One end of the front output flange 2 is located inside the front output hole 1.1. A bidirectional oil seal located inside the front output hole 1.1 is provided on the front output flange 2. A dust cover 4 is provided on the front output flange 2 and fixed relative to the front output flange 2. A shaft hole is provided on the front output flange 2. The front output shaft 3 passes through the shaft hole and is fixed to the front output flange 2. The front output shaft 3 and the shaft hole are sealed by an inner sealing ring 5 of the flange.

[0027] The front output flange 2 has a first ring neck 201 and a second ring neck 202 arranged coaxially. The outer diameter of the second ring neck 202 is larger than the outer diameter of the first ring neck 201. The end face of the second ring neck 202 facing the first ring neck 201 is the inner sealing ring face 202a. An oil seal space 201.1 is formed between the first ring neck 201 and the wall of the front output hole 1.1. A narrowing space 202.1 is formed between the second ring neck 202 and the wall of the front output hole 1.1. The end of the oil seal space 201.1 away from the narrowing space 202.1 is covered by a dust cover 4.

[0028] The bidirectional oil seal is located within the oil seal space 201.1. The bidirectional oil seal includes an oil seal base 601 that is sealed and fixed to the wall of the front output hole 1.1, an inner sealing lip 602 that is rotatably sealed to the front output shaft 3, and an outer waterproof lip 603 that is rotatably sealed to the front output shaft 3. The oil seal base 601 is provided with a side waterproof lip 604 that is rotatably sealed to the inner sealing ring surface 202a. The distance between the side waterproof lip 604 and the first ring neck 201 gradually increases from the direction adjacent to the oil seal base 601 to the direction away from the oil seal base 601.

[0029] The dust cover 4 can initially block splashed sand, mud, and water, thereby preventing a large amount of sand and mud that would otherwise enter the front outlet 1.1 from entering. This ensures that only a small amount of sand and mud can enter the oil seal space 201.1 (thus, the accumulation of sand and mud in the oil seal space 201.1 will be very slow, and some of the sand and mud will leave again from the bottom of the oil seal space 201.1), thus protecting the internal bidirectional oil seal.

[0030] The inner oil lip 602 of the bidirectional oil seal is a critical component, preventing oil leakage from the main housing 1 (transmission housing) and preventing external impurities (sand, mud, water, etc.) from entering the main housing 1. The outer waterproof lip 603 prevents sand, mud, water, etc., entering the oil seal space 201.1 from directly contacting the inner oil lip 602, thereby extending the service life of the inner oil lip 602. When the vehicle is driving and braking, the main acceleration direction is forward and backward. Sand, mud, water, etc., entering the oil seal space 201.1 will also move back and forth due to inertia and other factors. When the sand, mud, water, and other particles move backward relative to the front output shaft 3, the sand, mud, water, and other particles near the contact point between the outer waterproof lip 603 and the front output shaft 3 will impact and squeeze the outer waterproof lip 603. Once sand, mud, water, and other particles are slightly squeezed between the outer waterproof lip 603 and the front output shaft 3, the relative rotation of the outer waterproof lip 603 and the front output shaft 3 will accelerate the damage to the outer waterproof lip 603.

[0031] In this invention, a crucial side waterproof lip 604 is provided at the front, such as... Figure 1 , Figure 2 , Figure 4As can be seen, the side waterproof lip 604 is similar to an outwardly flared horn shape. This means that when a small amount of sand and mud enters the oil seal space 201.1 and moves back and forth due to vehicle movement and braking, it is less likely to directly reach the vicinity between the side waterproof lip 604 and the inner sealing ring surface 202a. Instead, it is more likely to reach the area between the side waterproof lip 604 and the oil seal base 601, or the middle of the outer wall of the side waterproof lip 604. However, these parts do not have a sealing function, so their impact is minimal. Sand and mud are even less likely to squeeze into the area between the side waterproof lip 604 and the inner sealing ring surface 202a (sand and mud near the area between the side waterproof lip 604 and the inner sealing ring surface 202a need to move vertically to squeeze into this area). Therefore, the side waterproof lip 604 provides extremely strong protection, greatly increasing the service life of the outer waterproof lip 603 and effectively ensuring that the bidirectional oil seal is less prone to premature failure.

[0032] Furthermore, sand and mud must first pass through the space between the front output flange 2 and the front output hole 1.1 (the outer part) before entering the oil seal space 201.1. In this invention, the space between the front output flange 2 and the front output hole 1.1 (the outer part) is directly designed as a narrowing space 202.1. This is equivalent to using the larger size of the second ring neck 202 relative to the first ring neck 201 to make the narrowing space 202.1 very small, increasing the difficulty for sand and mud to enter the oil seal space 201.1 through the narrowing space 202.1, thus improving the protective effect. The inner sealing ring 5 of the flange can prevent oil from leaking into the front output flange 2.

[0033] The front output hole 1.1 includes an inner output section and an outer output section. The oil seal base 601 is sealed and fixed to the inner output section hole wall. The inner diameter of the outer output section, the outer diameter of the second journal, the inner diameter of the inner output section, and the outer diameter of the first journal decrease in sequence.

[0034] In this design, the narrowing space 202.1 and the oil seal space 201.1 are not "directly aligned" but "staggered", which further increases the difficulty for sand and mud to enter the oil seal space 201.1 through the narrowing space 202.1, and further enhances the protective effect.

[0035] The front output flange 2 has a third journal 203 and a fourth conical journal 204 located outside the front output hole 1.1. The minimum outer diameter of the fourth conical journal 204 is larger than the outer diameter of the third ring journal. The end face of the fourth conical journal 204 facing the third ring journal is the outer positioning ring face. The dust cover 4 includes an inner cylinder cover 401, a ring plate cover 402 and an outer cylinder cover 403 arranged coaxially. The outer end of the inner cylinder cover 401 is connected to the inner edge of the ring plate cover 402. The outer end of the outer cylinder cover 403 is connected to the outer edge of the ring plate cover 402. The inner side wall of the inner cylinder cover 401 is in contact with the outer side wall of the third ring journal. The outer end of the ring plate is in contact with the outer positioning ring face. The main housing 1 is provided with a limiting ring groove 1.2 with an opening facing the fourth conical journal 204. The inner end of the outer cylinder cover 403 is located in the limiting ring groove 1.2.

[0036] The dust cover 4 is directly attached to and fixed relative to the outer positioning ring surface and the outer wall of the third ring neck. In traditional dust covers 4, the outer cylindrical cover 403 is generally directly fitted onto a protrusion of the main housing 1. Therefore, the outer cylindrical cover 403 lacks a limiting mechanism. Since the dust cover 4 is fixed relative to the front output flange 2, and the front output flange 2 rotates together with the front output shaft 3, the dust cover 4 must rotate relative to the main housing 1. Therefore, under the influence of vibration and other factors, the outer cylindrical cover 403 of the traditional dust cover 4 is more prone to loosening relative to the main housing 1, making it easier for sand, dust, and mud to enter the front output hole 1.1. In this solution, a limiting ring groove 1.2 is opened on the main housing 1 to simultaneously limit the outer cylindrical cover 403 of the dust cover 4 from both the inner and outer sides. This solution is also cost-effective, and the installation of the dust cover 4 is convenient, preventing the outer cylindrical cover 403 from loosening relative to the main housing 1 and ensuring the protective effect.

[0037] The inner sealing ring surface 202a is provided with an inwardly tapered flange ring 205 protruding toward the oil seal base 601. The inner diameter of the inwardly tapered flange ring 205 is larger than the maximum outer diameter of the side waterproof lip 604, and there is a margin gap between the inwardly tapered flange ring 205 and the side waterproof lip 604.

[0038] The inward-facing flange helps protect the side waterproof lip 604. When sand and mud enter the oil seal space 201.1 through the narrowing space 202.1, they will first pass through the outer wall of the inward-facing flange. This makes it less likely for the area between the side waterproof lip 604 and the inner sealing ring surface 202a to directly contact sand and mud. When sand and mud compress the outer wall of the side waterproof lip 604, the end of the side waterproof lip 604 that contacts the inner sealing ring surface 202a may move slightly outward (i.e., the opening at the outer end of the side waterproof lip 604 becomes slightly larger), and the middle of the outer wall of the side waterproof lip 604 will slightly retract inward. This design incorporates a margin clearance, ensuring that the side waterproof lip 604 can undergo reasonable deformation and displacement without affecting the seal.

[0039] The oil seal base 601 is provided with a metal skeleton plate 605, which includes a vertical ring plate 605.1 and a horizontal cylindrical plate 605.2. The outer edge of the vertical ring plate 605.1 is coaxially fixed with one end of the horizontal cylindrical plate 605.2. The oil seal base 601 is provided with a metal retaining ring 601.1 for pressing the inner sealing lip 602. The metal retaining ring 601.1 is sleeved on the outside of the inner sealing lip 602. The oil seal base 601 is provided with an intermediate lip 606 located between the inner sealing lip 602 and the outer waterproof lip 603. The intermediate lip 606 is rotatably sealed with the front output shaft 3.

[0040] The oil seal base 601 is to be sealed and fixed to the wall of the front output port 1.1, and it is the basic structure of the entire oil seal part. It must have a certain rigidity. The metal skeleton plate 605 can provide rigidity guarantee for the oil seal base 601 from both radial and axial dimensions. The presence of the intermediate lip 606, in addition to providing an extra layer of protection, can also play a radial support role, reasonably and appropriately increasing the deformation difficulty of the outer waterproof lip 603, thereby improving its sealing effect.

[0041] The outer end of the shaft hole opens into the inner end face 2a of the front output flange 2. The front output shaft 3 is provided with a front shaft head section 301 located inside the front output flange 2. The diameter of the front shaft head section 301 is smaller than the diameter of the front output shaft 3. The flange inner sealing ring 5 is sleeved on the front shaft head section 301. The flange inner sealing ring 5 includes a high ring inner ring 501 that contacts the outer wall of the front shaft head section 301 and a flat ring outer ring 502 that contacts the wall of the front shaft hole. The flat ring outer ring 502 is sleeved outside the high ring inner ring 501.

[0042] In the axial direction of the front output shaft 3: the length of the inner ring 501 of the high ring is greater than the length of the outer ring 502 of the flat ring. One end of the inner ring 501 of the high ring, one end of the front shaft hole, the other end of the inner ring 501 of the high ring and the front output shaft 3 are arranged in sequence. The inner end face 2a of the front output flange 2, the outer ring 502 of the flat ring and the front output shaft 3 are arranged in sequence.

[0043] The front axle head section 301 is fitted with a gasket 302 for pressing the inner ring 501 of the high ring and can be attached to the inner end face 2a of the front output flange 2. The front axle head section 301 is provided with a lock nut 303 for pressing the gasket 302. The lock nut 303 is threadedly engaged with the front axle head section 301.

[0044] As mentioned earlier, the inner sealing ring 5 of the flange prevents oil leakage into the front output flange 2. Compared to the traditional form, this utility model adopts a sealing ring form that combines a thicker high-ring inner ring 501 with a normally thick flat-ring outer ring 502 (the high-ring inner ring 501 and the flat-ring outer ring 502 are integrally formed). Thus, when the lock nut 303 pushes the gasket 302 to compress the high-ring inner ring 501, the thickness of the high-ring inner ring 501 decreases, compressing the flat-ring outer ring 502 from multiple directions, thereby better ensuring the sealing effect. Furthermore, after the gasket 302 contacts the inner end face 2a of the flange, it cannot move further inward, so it will not excessively compress the flat-ring outer ring 502, thus protecting the flat-ring outer ring 502 and ensuring its normal sealing function (excessive compression would lead to problems such as damage or premature failure of the flat-ring outer ring 502).

[0045] The embodiments of this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A sealing structure for the front output shaft flange end of a transfer case, the transfer case including a main housing, a front output flange, and a front output shaft, the main housing having a front output hole, one end of the front output flange being located within the front output hole, a bidirectional oil seal being fitted over the front output flange and located within the front output hole, a dust cover fixed relative to the front output flange being provided on the front output flange, a shaft hole being provided on the front output flange, the front output shaft passing through the shaft hole and being fixed to the front output flange, and a sealing ring being provided between the front output shaft and the shaft hole; characterized in that... The front output flange has a first ring neck and a second ring neck arranged coaxially. The outer diameter of the second ring neck is larger than that of the first ring neck. The end face of the second ring neck facing the first ring neck is the inner sealing ring face. An oil seal space is formed between the first ring neck and the wall of the front output hole. A narrowing space is formed between the second ring neck and the wall of the front output hole. The end of the oil seal space away from the narrowing space is covered by a dust cover. The bidirectional oil seal is located within the oil seal space. The bidirectional oil seal includes an oil seal base that is sealed and fixed to the wall of the front output hole, an inner sealing lip that rotates and seals with the front output shaft, and an outer waterproof lip that rotates and seals with the front output shaft. The oil seal base is provided with a side waterproof lip that rotates and seals with the inner sealing ring surface. The distance between the side waterproof lip and the first ring neck gradually increases from the direction adjacent to the oil seal base to the direction away from the oil seal base.

2. A seal structure for a front output shaft flange end of a transfer, as set forth in claim 1, wherein, The front output hole includes an inner output section and an outer output section. The oil seal base is sealed and fixed to the inner output section hole wall. The inner diameter of the outer output section, the outer diameter of the second journal, the inner diameter of the inner output section, and the outer diameter of the first journal decrease in sequence.

3. A seal structure for a front output shaft flange end of a transfer, as set forth in claim 1, wherein, The front output flange has a third journal and a fourth conical journal outside the front output hole. The minimum outer diameter of the fourth conical journal is greater than the outer diameter of the third ring journal. The end face of the fourth conical journal facing the third ring journal is the outer positioning ring face. The dust cover includes an inner cylinder cover, a ring plate cover and an outer cylinder cover arranged coaxially. The outer end of the inner cylinder cover is connected to the inner edge of the ring plate cover, and the outer end of the outer cylinder cover is connected to the outer edge of the ring plate cover. The inner side wall of the inner cylinder cover is in contact with the outer side wall of the third ring journal, and the outer end of the ring plate is in contact with the outer positioning ring face. The main housing is provided with a limiting ring groove with an opening facing the fourth conical journal. The inner end of the outer cylinder cover is located in the limiting ring groove.

4. A seal structure for a front output shaft flange end of a transfer, according to claim 1 or 2 or 3, characterized in that, The inner sealing ring surface is provided with an inwardly tapered flange ring that protrudes toward the oil seal substrate. The inner diameter of the inwardly tapered flange ring is larger than the maximum outer diameter of the side waterproof lip, and there is a margin gap between the inwardly tapered flange ring and the side waterproof lip.

5. A seal for a front output shaft flange end of a transfer case as defined in claim 1, wherein, The oil seal base is provided with a metal skeleton plate, which includes a vertical ring plate and a horizontal cylindrical plate. The outer edge of the vertical ring plate is coaxially fixed with one end of the horizontal cylindrical plate. The oil seal base is provided with a metal retaining ring for pressing the inner oil lip. The metal retaining ring is sleeved on the outside of the inner oil lip. The oil seal base is provided with an intermediate lip located between the inner oil lip and the outer waterproof lip. The intermediate lip is rotatably sealed with the front output shaft.

6. A seal structure for a front output shaft flange end of a transfer, according to claim 1 or 2 or 3, characterized in that, The outer end of the shaft hole opens into the inner end face of the front output flange. The front output shaft is provided with a front shaft head section located inside the front output flange. The diameter of the front shaft head section is smaller than the diameter of the front output shaft. The flange inner sealing ring is sleeved on the front shaft head section. The flange inner sealing ring includes a high ring inner ring that contacts the outer wall of the front shaft head section and a flat ring outer ring that contacts the wall of the front shaft hole. The flat ring outer ring is sleeved outside the high ring inner ring. On the axial direction of the front output shaft: the length of the inner ring of the high ring is greater than the length of the outer ring of the flat ring. One end of the inner ring of the high ring, one end of the front shaft hole, the other end of the inner ring of the high ring and the front output shaft are arranged in sequence. The inner end face of the front output flange, the outer ring of the flat ring and the front output shaft are arranged in sequence. The front axle head section is fitted with a gasket for pressing the inner ring of the high ring and can be attached to the inner end face of the front output flange. The front axle head section is also equipped with a lock nut for pressing the gasket, and the lock nut is threadedly engaged with the front axle head section.

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