Shift shaft sealing structure

Abstract

The application discloses a shift shaft sealing structure, which can effectively prevent lubricating oil in a transmission housing from leaking to the outside of the transmission housing and effectively prevent impurities and the like from the outside from entering the transmission housing. The sealing insurance structure is configured, and no matter whether the first sealing structure inside or outside fails, the second sealing structure can be provided to perform sealing protection, and the overall sealing effect is good. The main structure of the application comprises a main shaft hole, a main oil seal and a shift shaft. The main oil seal comprises an oil seal outer base body, a first sealing lip, a second sealing lip and a third sealing lip. A dust cover is arranged on the shift shaft. The dust cover comprises an inner section fixed part, a middle section elastic cover and an outer section fixed part. The inner section fixed part is sealingly connected with the oil seal outer base body. The middle section elastic cover is provided with a gas pressure balance hole. The outer section fixed part is sleeved on the shift shaft, and the outer section fixed part is in rotating sealing cooperation with the shift shaft.

Description

Technical Field

[0001] This invention belongs to the field of vehicle transmission technology, and particularly relates to a shift shaft sealing structure. Background Technology

[0002] A manual transmission is a gearbox system used to change the speed and torque transmitted from the engine to the drive wheels. It allows the car to obtain different traction and speeds under various operating conditions such as starting from a standstill, climbing hills, turning, and accelerating, while simultaneously ensuring the engine operates within a more favorable range. The shift shaft is a crucial moving component in a manual transmission; part of it is located outside the transmission housing, and the other part is inside. Considering the lubricating oil inside the transmission housing and the impurities and moisture in the outside air, a sealing ring-like structure (often a shift shaft oil seal) is installed between the shift shaft and the transmission housing. This seal must prevent oil leakage (preventing lubricating oil from leaking out of the transmission housing) and also prevent impurities and moisture from entering the transmission housing.

[0003] Explanation: The shift shaft structure itself is existing technology. It can move axially and rotate along its own axis. The shift shaft has three positioning positions in the axial direction: inner positioning position, middle positioning position, and outer positioning position. When the shift shaft moves to its limit position inside the transmission housing, it is in the inner positioning position. When the shift shaft is in the middle positioning position, the transmission gear is neutral. When the shift shaft moves to its limit position outside the transmission housing, it is in the outer positioning position. The shift shaft needs to work in conjunction with several shift push rods (also called shift levers) and other structures inside the transmission housing to achieve multi-gear switching. Summary of the Invention

[0004] This invention provides a shift shaft sealing structure that effectively prevents lubricating oil inside the transmission housing from leaking out of the transmission housing internally, and effectively prevents external impurities from entering the transmission housing externally. It is also equipped with a sealing safety structure that provides a second sealing structure to ensure sealing regardless of whether the first internal or external sealing structure fails. The overall sealing effect is excellent.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A shift shaft sealing structure includes a main shaft hole on a transmission housing, a main oil seal on the main shaft hole, and a shift shaft passing through the main oil seal. The shift shaft is in sliding sealing engagement with the main oil seal, and the shift shaft is in rotating sealing engagement with the main oil seal. On the upward axis of the shift shaft: The shift shaft has three positioning positions: inner positioning position, middle positioning position and outer positioning position. When the shift shaft moves to the limit position inside the transmission housing, the shift shaft is in the inner positioning position. When the shift shaft is in the middle positioning position, the transmission gear is neutral. When the shift shaft moves to the limit position outside the transmission housing, the shift shaft is in the outer positioning position. The main oil seal includes an outer base that is sealed and fixed to the main shaft bore, and a first sealing lip, a second sealing lip, and a third sealing lip arranged sequentially along the axial direction of the shift shaft. The portion of the first sealing lip that contacts the shift shaft is the first sealing part, and the first sealing part is located inside the main shaft bore. The portion of the second sealing lip that contacts the shift shaft is the second sealing part, and the second sealing part is located inside the main shaft bore. The portion of the third sealing lip that contacts the shift shaft is the third sealing part, and the third sealing part is located outside the transmission housing. An inner annular groove with an opening facing the spindle hole is formed between the first sealing lip and the outer base of the oil seal, and an outer annular groove with an opening facing away from the spindle hole is formed between the third sealing lip and the outer base of the oil seal. The shift shaft is provided with a dust cover, which includes an inner section fixing part, a middle section elastic cover and an outer section fixing part. The inner section fixing part is sealed to the outer base of the oil seal. The middle section elastic cover is provided with an air pressure balance hole. The outer section fixing part is sleeved on the shift shaft and is rotatably sealed with the shift shaft.

[0006] Preferably, the oil seal outer substrate includes a metal skeleton cylinder and a rubber substrate wrapped around the metal skeleton cylinder. The metal skeleton cylinder includes a skeleton cylinder and a flanged ring disposed at one end of the skeleton cylinder. The skeleton cylinder is coaxially arranged with the shift shaft, and the flanged ring is coaxially arranged with the shift shaft.

[0007] Preferably, the connection point between the inner section fixing part and the outer base of the oil seal is located outside the metal skeleton cylinder, the first sealing part is located inside the metal skeleton cylinder, the second sealing part is located inside the metal skeleton cylinder, and the third sealing part is located inside the metal skeleton cylinder.

[0008] Preferably, the middle section elastic cover is provided with an adjusting ring located adjacent to the inner section fixed part. The adjusting ring is fixed to the middle section elastic cover. The middle section elastic cover is provided with a collar for contacting and squeezing the third sealing lip. The collar is fixed to the adjusting ring by several connecting rods. When the adjusting ring contacts the inner section fixing part: the collar is in the outer middle ring groove, the collar contacts and squeezes the third sealing lip, and the vertical projection of the collar and the vertical projection of the third sealing part overlap; When the shift shaft is in the middle positioning position: the adjusting ring is separated from the inner fixed part, and the collar is outside the outer middle ring groove.

[0009] Preferably, during the entire process of the shift shaft moving from the intermediate positioning position to the inner positioning position, in the axial direction of the shift shaft: if the shift shaft moves a distance of 10Y, then the collar moves a distance less than Y.

[0010] Preferably, the third sealing lip is provided with a narrow air passage and a large annular cavity surrounding the third sealing part. The large annular cavity is arranged coaxially with the shift shaft. One end of the narrow air passage is connected to the large annular cavity, and the other end of the narrow air passage is a small opening connected to the outer middle annular groove. When the adjusting ring contacts the inner section fixing part, the volume of the large annular cavity is 0.

[0011] Preferably, the end of the first sealing lip away from the second sealing lip extends toward the inner ring groove to form a first lip flange. The inner ring groove is provided with a spring ring for pressing the first sealing lip onto the shift shaft. The first lip flange and the spring ring are tightly fitted together. The first lip flange, the spring ring, and the second sealing lip are arranged sequentially along the axial direction of the shift shaft.

[0012] Preferably, the main shaft hole is composed of a small diameter shaft hole and a large diameter shaft hole. The small diameter shaft hole and the large diameter shaft hole are coaxial and connected. One end of the large diameter shaft hole is connected to the outside of the transmission housing. The main oil seal is provided on the large diameter shaft hole. A sliding bearing is provided in the small diameter shaft hole. The shift shaft is connected to the sliding bearing and is slidably connected to the small diameter shaft hole through the sliding bearing.

[0013] The beneficial effects of this invention are as follows: Internally, it effectively prevents lubricating oil inside the transmission housing from leaking out of the transmission housing; externally, it effectively prevents impurities from entering the transmission housing. Furthermore, it is equipped with a sealing and safety structure, providing a second sealing structure to ensure sealing regardless of whether the first internal or external sealing structure fails, resulting in excellent overall sealing performance. During the movement of the shift shaft towards the inside of the transmission housing, the ability of the third sealing lip to maintain its shape is enhanced at a certain point, further preventing impurities from damaging the third sealing lip and the shift shaft. During the movement of the shift shaft towards the outside of the transmission housing, the local deformation capability of the third sealing lip is relatively strong, which helps impurities leave the third sealing part. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention; Figure 2 This is a partial structural schematic diagram of Embodiment 1 of the present invention; Figure 3 yes Figure 2 Enlarged view of point A in the middle; Figure 4 This is a partial structural schematic diagram of Embodiment 2 of the present invention; Figure 5 yes Figure 4 Enlarged view of point B in the middle; Figure 6 This is a schematic diagram of the structure of the adjusting ring in Embodiment 2 of the present invention; Figure 7 yes Figure 6 Enlarged view of point C in the middle.

[0015] Reference numerals: 1. Transmission housing; 1a. Main shaft hole; 1b. Small diameter shaft hole; 1c. Large diameter shaft hole; 2. Main oil seal; 2a. Inner middle ring groove; 2b. Outer middle ring groove; 201. Oil seal outer base; 201.1. Metal skeleton cylinder; 201.1a. Skeleton cylinder; 201.1b. Flanged cylinder ring; 201.2. Rubber base; 202. First sealing lip; 202.1. First lip flange; 203. Third sealing lip; 204. Fine air passage; 204a. Large ring cavity; 204b. Shift shaft; 3. Dust cover; 4. Inner section fixing part; 401. Middle section elastic cover; 402. Air pressure balance hole; 402a. Outer section fixing part; 403. Adjusting ring; 501. Collar; 502. Connecting rod; 6. Spring ring. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1:

[0018] like Figure 1 , Figure 2 , Figure 3 As shown, a shift shaft sealing structure includes a main shaft hole 1a provided on the transmission housing 1, a main oil seal 2 provided on the main shaft hole 1a, and a shift shaft 3 passing through the main oil seal 2. The shift shaft 3 is in sliding sealing cooperation with the main oil seal 2, and the shift shaft 3 is in rotating sealing cooperation with the main oil seal 2. On the axial direction of the shift shaft 3: the shift shaft 3 has three positioning positions: inner positioning position, middle positioning position and outer positioning position. When the shift shaft 3 moves towards the inside of the transmission housing 1 to the limit position, the shift shaft 3 is in the inner positioning position. When the shift shaft 3 is in the middle positioning position, the transmission gear is neutral. When the shift shaft 3 moves towards the outside of the transmission housing 1 to the limit position, the shift shaft 3 is in the outer positioning position. The main oil seal 2 includes an outer base 201 that is sealed and fixed to the main shaft hole 1a, and a first sealing lip 202, a second sealing lip 203, and a third sealing lip 204 arranged sequentially along the axial direction of the shift shaft 3. The part of the first sealing lip 202 that contacts the shift shaft 3 is the first sealing part, and the first sealing part is located inside the main shaft hole 1a. The part of the second sealing lip 203 that contacts the shift shaft 3 is the second sealing part, and the second sealing part is located inside the main shaft hole 1a. The part of the third sealing lip 204 that contacts the shift shaft 3 is the third sealing part, and the third sealing part is located outside the transmission housing 1. An inner annular groove 2a with an opening facing the spindle hole 1a is formed between the first sealing lip 202 and the outer base of the oil seal 201, and an outer annular groove 2b with an opening facing away from the spindle hole 1a is formed between the third sealing lip 204 and the outer base of the oil seal 201. The shift shaft 3 is provided with a dust cover 4, which includes an inner section fixing part 401, a middle section elastic cover 402 and an outer section fixing part 403. The inner section fixing part 401 is sealed to the oil seal outer base 201. The middle section elastic cover 402 is provided with a pressure balance hole 402a. The outer section fixing part 403 is sleeved on the shift shaft 3 and is rotatably sealed to the shift shaft 3.

[0019] The outer base 201 of the oil seal is sealed and fixed to the main shaft hole 1a. Internally, the first sealing lip 202 seals with the shift shaft 3 to form a first sealing part, preventing lubricating oil inside the transmission housing 1 from leaking out. Externally, the third sealing lip 204 seals with the shift shaft 3 to form a third sealing part, preventing external impurities from entering the transmission housing 1. Furthermore, a second sealing lip 203 is provided in the middle, sealing with the shift shaft 3 to form a second sealing part, serving as a second layer of sealing protection.

[0020] In addition, a deformable dust cover 4 is provided externally. The inner section fixing part 401 and the outer section fixing part 403 of the dust cover 4 are rigid structures, while the middle section elastic cover 402 of the dust cover 4 is an elastic structure that can adaptably close and open. When the shift shaft 3 moves towards the inside of the transmission housing 1, the middle section elastic cover 402 of the dust cover 4 closes, and some of the air inside the middle section elastic cover 402 is discharged from the air pressure balance hole 402a. When the shift shaft 3 moves towards the outside of the transmission housing 1, the middle section elastic cover 402 of the dust cover 4 opens, and outside air enters the middle section elastic cover 402 from the air pressure balance hole 402a. With the dust cover 4, impurities and moisture can only enter the middle section elastic cover 402 through the air pressure balance hole 402a and then come into contact with the third sealing lip 204. Compared with the case of direct exposure, the negative impact of impurities and moisture on the third sealing lip 204 (third sealing part) is greatly reduced in this solution.

[0021] like Figure 2 , Figure 3 As shown, the oil seal outer substrate 201 includes a metal skeleton cylinder 201.1 and a rubber substrate 201.2 wrapped around the metal skeleton cylinder 201.1. The metal skeleton cylinder 201.1 includes a skeleton cylinder 201.1a and a flanged cylindrical ring 201.1b disposed at one end of the skeleton cylinder 201.1a. The skeleton cylinder 201.1a is coaxially arranged with the shift shaft 3, and the flanged cylindrical ring 201.1b is coaxially arranged with the shift shaft 3.

[0022] Frequent gear shifting requires the main oil seal 2 to maintain its shape effectively to ensure sealing both internally and externally. The metal skeleton cylinder 201.1 installed inside the outer substrate 201 of the oil seal effectively enhances the main oil seal 2's ability to maintain its shape, especially ensuring a secure seal between the main oil seal 2 and the spindle hole 1a, preventing excessive deformation of the main oil seal 2 that could lead to seal failure.

[0023] like Figure 2 , Figure 3 As shown, the connection position between the inner section fixing part 401 and the oil seal outer base 201 is outside the metal skeleton cylinder 201.1, the first sealing part is inside the metal skeleton cylinder 201.1, the second sealing part is inside the metal skeleton cylinder 201.1, and the third sealing part is inside the metal skeleton cylinder 201.1.

[0024] The metal skeleton cylinder 201.1 has the ability to "isolate the deformation and vibration transmission of the main oil seal 2" to a certain extent. Specifically, without the metal skeleton cylinder 201.1, when the deformation of the outer base 201 of the oil seal is large, the first sealing lip 202, the second sealing lip 203, and the third sealing lip 204 are also more easily affected by the deformation of the outer base 201 of the oil seal, or when the deformation of the first sealing lip 202, the second sealing lip 203, and the third sealing lip 204 is large, the outer base 201 of the oil seal is also more easily affected by the deformation of the first sealing lip 202, the second sealing lip 203, and the third sealing lip 204. The metal skeleton cylinder 201.1 can increase the rigidity of the outer base 201 of the oil seal and eliminate some of the deformation transmission, thereby improving the positioning stability and relative strength of the entire main oil seal 2. On this basis, the vibration of the inner section fixing part 401 will also have less impact on the first sealing lip 202, the second sealing lip 203, and the third sealing lip 204.

[0025] like Figure 2 , Figure 3As shown, the end of the first sealing lip 202 away from the second sealing lip 203 extends toward the inner annular groove 2a to form a first lip flange 202.1. The inner annular groove 2a is provided with a spring ring 6 for pressing the first sealing lip 202 onto the shift shaft 3. The first lip flange 202.1 and the spring ring 6 are closely attached to each other. The first lip flange 202.1, the spring ring 6 and the second sealing lip 203 are arranged sequentially along the axial direction of the shift shaft 3.

[0026] The spring ring 6 can further enhance the sealing effect between the first sealing lip 202 and the shift shaft 3, ensuring the stability of the shape of the first sealing part. The first lip flange 202.1 can also better position the spring ring 6 and prevent the spring ring 6 from sliding axially (axially) towards the shift shaft 3.

[0027] like Figure 1 As shown, the main shaft hole 1a is composed of a small diameter shaft hole 1b and a large diameter shaft hole 1c. The small diameter shaft hole 1b and the large diameter shaft hole 1c are coaxial and connected. One end of the large diameter shaft hole 1c is connected to the outside of the transmission housing 1. The main oil seal 2 is located on the large diameter shaft hole 1c. A sliding bearing is provided in the small diameter shaft hole 1b. The shift shaft 3 is connected to the sliding bearing and is slidably connected to the small diameter shaft hole 1b through the sliding bearing.

[0028] The sliding bearing can assist in supporting and guiding the shift shaft 3, thereby improving the stability of the shift shaft 3 during operation.

[0029] Example 2:

[0030] Based on Example 1, such as Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, the middle section elastic cover 402 is provided with an adjusting ring 501 located adjacent to the inner section fixing part 401. The adjusting ring 501 is fixed to the middle section elastic cover 402. The middle section elastic cover 402 is provided with a collar 502 for contacting and pressing the third sealing lip 204. The collar 502 is fixed to the adjusting ring 501 by several connecting rods 503. When the adjusting ring 501 contacts the inner section fixing part 401: the collar 502 is in the outer middle ring groove 2b, the collar 502 contacts and squeezes the third sealing lip 204, and the vertical projection of the collar 502 and the vertical projection of the third sealing part have an overlapping part. When the shift shaft 3 is in the middle positioning position: the adjusting ring 501 is separated from the inner section fixing part 401, and the collar 502 is outside the outer middle ring groove 2b.

[0031] One of the main functions of the third sealing lip 204 is to block external impurities and prevent them from passing through the third sealing part. Therefore, the tight fit between the third sealing lip 204 and the shift shaft 3 is very important. In actual operation, when the shift shaft 3 moves towards the inside of the transmission housing 1, the end of the third sealing lip 204 away from the transmission housing 1 will be slightly deformed inward (towards the transmission housing 1) by the moving shift shaft 3. (Originally, the part of the third sealing lip 204 in contact with the shift shaft 3 is the third sealing part, and the surface of the end of the third sealing lip 204 away from the transmission housing 1 does not contact the shift shaft 3. However, due to the aforementioned "the end of the third sealing lip 204 away from the transmission housing 1 will be slightly deformed inward by the moving shift shaft 3", thus, a small portion of the surface of the end of the third sealing lip 204 away from the transmission housing 1, adjacent to the shift shaft 3, will become part of the third sealing part and adhere to the shift shaft 3. That is, the third sealing lip 204...) 4. A small section away from the transmission housing 1 will be slightly "arched". As a result, impurities that are located at the end of the third sealing lip 204 away from the transmission housing 1 and on the shift shaft 3 may enter between the third sealing lip 204 and the shift shaft 3, that is, enter the third sealing part. The key problem is that once the impurities enter the third sealing part, they are difficult to leave. Although the shift shaft 3 will have an outward pulling force on the impurities when it moves towards the outside of the transmission housing 1, the third sealing lip 204 is elastic and will press the impurities onto the shift shaft 3. Therefore, it is difficult for the impurities in the third sealing part to be carried away. And the impurities are in the third sealing part for a long time, which can easily scratch the moving shift shaft 3 and accelerate the wear of the third sealing lip 204.

[0032] Furthermore, if impurities damage the third sealing lip 204, as the shift shaft 3 moves toward the inside of the transmission housing 1 time and time again, then, as described above, the impurities may enter the second sealing part, damage the second sealing lip 203 and the shift shaft 3, and even damage the first sealing lip 202, which is obviously even more unacceptable.

[0033] In view of the above reasons, this embodiment provides a targeted solution to the problem. First, when the shift shaft 3 is in the middle positioning position: the adjusting ring 501 is separated from the inner section fixing part 401, and the collar 502 is outside the outer middle ring groove 2b, at which time nothing happens. When the shift shaft 3 moves towards the inside of the transmission housing 1, the middle section elastic cover 402 of the dust cover 4 retracts, and the adjusting ring 501 adjacent to the inner section fixing part 401 quickly contacts the inner section fixing part 401 (then the dust cover 4 continues to retract). At this time, "the collar 502 is in the outer middle ring groove 2b, the collar 502 contacts and squeezes the third sealing lip 204, and the vertical projection of the collar 502 overlaps with the vertical projection of the third sealing part", which means that the collar 502 will assist in the third sealing lip 204. The sealing lip 204 is further pressed against the shift shaft 3. This restricts the deformation of the third sealing lip 204, making it more difficult for the end of the third sealing lip 204 away from the transmission housing 1 to be slightly deformed inward by the shift shaft 3. In other words, the end of the third sealing lip 204 away from the transmission housing 1 is less likely to be slightly deformed inward by the shift shaft 3. As a result, the third sealing lip 204 can maintain its shape, making it difficult for impurities to penetrate the deformation and enter the third sealing section. This effectively prevents impurities from entering and further protects the third sealing lip 204 and the shift shaft 3.

[0034] During the entire process of the shift shaft 3 moving from the middle positioning position to the inner positioning position, in the axial direction of the shift shaft 3: if the shift shaft 3 moves a distance of 10Y, then the collar 502 moves a distance less than Y.

[0035] As mentioned earlier, when the shift shaft 3 moves towards the inside of the transmission housing 1, the middle section elastic cover 402 of the dust cover 4 retracts, and the adjusting ring 501 adjacent to the inner section fixing part 401 quickly contacts the inner section fixing part 401 (after which the dust cover 4 continues to retract). This is because the adjusting ring 501 is very close to the inner section fixing part 401. Therefore, when the shift shaft 3 is in the middle positioning position, if the dust cover 4 begins to retract, the adjusting ring 501 will contact the inner section fixing part 401 in the early stage of the dust cover 4 retraction. Thus, the collar 502 will also contact and squeeze the third sealing lip 204 in the early stage of the retraction. This ensures that the third sealing lip 204 has a high ability to maintain its shape during the subsequent movement of the shift shaft 3, which can further prevent impurities from entering the third sealing part.

[0036] The third sealing lip 204 is provided with a narrow air passage 204a and a large annular cavity 204b surrounding the third sealing part. The large annular cavity 204b is arranged coaxially with the shift shaft 3. One end of the narrow air passage 204a is connected to the large annular cavity 204b, and the other end of the narrow air passage 204a is a small opening connected to the outer middle annular groove 2b. When the adjusting ring 501 contacts the inner section fixing part 401, the volume of the large annular cavity 204b is 0.

[0037] Based on the preceding description of this embodiment, when the adjusting ring 501 contacts the inner section fixing part 401, the collar 502 contacts and squeezes the third sealing lip 204, and the volume of the large annular cavity 204b is 0. This means that when the adjusting ring 501 contacts the inner section fixing part 401, the large annular cavity 204b is flattened, so the third sealing lip 204 is still tightly pressed on the shift shaft 3. At this time, as in the preceding description, the ability of the third sealing lip 204 to maintain its shape is enhanced, and the end of the third sealing lip 204 away from the transmission housing 1 is less likely to be slightly deformed inward by the shift shaft 3, thus further preventing impurities from entering the third sealing part. Based on this, when the shift shaft 3 moves towards the outside of the transmission housing 1, the adjusting ring 501 adjacent to the inner section fixing part 401 quickly leaves the inner section fixing part 401 (after which the dust cover 4 continues to open). Then, the collar 502 also moves with the adjusting ring 501 and quickly leaves the outer middle ring groove 2b. At this time, under its own elasticity, the large ring cavity 204b returns to its shape. With the hollow large ring cavity 204b, when the shift shaft 3 continues to move towards the outside of the transmission housing 1, the third sealing lip 204 is more likely to deform (which can be simply understood as the third sealing lip 204 was originally solid, but now it is partially hollow). Therefore, the end of the third sealing lip 204 away from the transmission housing 1 is more likely to deform slightly outward (radially). Once this deformation occurs, a small section of the third sealing part away from the transmission housing 1 will disappear, which is equivalent to a slight separation between the end of the third sealing lip 204 away from the transmission housing 1 and the shift shaft 3. Therefore, any impurities that previously entered the third sealing lip 204 will be easily carried away by the shift shaft 3 and removed from the third sealing lip 204 (at this point, the third sealing lip 204 does not tightly press the impurities onto the shift shaft 3, and the third sealing lip 204 can be easily pushed open by the impurities). As a result, both the third sealing lip 204 and the shift shaft 3 are less susceptible to long-term, continuous damage, their service life is enhanced, and the stability of their operation is improved.

[0038] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. 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 the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A shift shaft sealing structure, comprising a main shaft hole (1a) disposed on a transmission housing (1), a main oil seal (2) disposed on the main shaft hole (1a) and a shift shaft (3) passing through the main oil seal (2), wherein the shift shaft (3) is in sliding sealing cooperation with the main oil seal (2) and the shift shaft (3) is in rotating sealing cooperation with the main oil seal (2); Along the axial direction of the shift shaft (3): the shift shaft (3) has three positioning positions: an inner positioning position, a middle positioning position, and an outer positioning position. When the shift shaft (3) moves towards the limit position inside the transmission housing (1), the shift shaft (3) is in the inner positioning position. When the shift shaft (3) is in the middle positioning position, the transmission gear is neutral. When the shift shaft (3) moves towards the limit position outside the transmission housing (1), the shift shaft (3) is in the outer positioning position. Its characteristic is that... The main oil seal (2) includes an outer base (201) that is sealed and fixed to the main shaft hole (1a) and a first sealing lip (202), a second sealing lip (203) and a third sealing lip (204) arranged sequentially along the axial direction of the shift shaft (3). The part of the first sealing lip (202) that contacts the shift shaft (3) is the first sealing part, and the first sealing part is located inside the main shaft hole (1a). The part of the second sealing lip (203) that contacts the shift shaft (3) is the second sealing part, and the second sealing part is located inside the main shaft hole (1a). The part of the third sealing lip (204) that contacts the shift shaft (3) is the third sealing part, and the third sealing part is located outside the transmission housing (1). An inner annular groove (2a) with an opening facing the main shaft hole (1a) is formed between the first sealing lip (202) and the outer base of the oil seal (201), and an outer annular groove (2b) with an opening facing away from the main shaft hole (1a) is formed between the third sealing lip (204) and the outer base of the oil seal (201). The shift shaft (3) is provided with a dust cover (4), which includes an inner section fixing part (401), a middle section elastic cover (402) and an outer section fixing part (403). The inner section fixing part (401) is sealed to the oil seal outer base (201). The middle section elastic cover (402) is provided with a pressure balance hole (402a). The outer section fixing part (403) is sleeved on the shift shaft (3) and the outer section fixing part (403) is rotatably sealed to the shift shaft (3).

2. The shift shaft sealing structure according to claim 1, characterized in that, The oil seal outer substrate (201) includes a metal skeleton cylinder (201.1) and a rubber substrate (201.2) wrapped around the metal skeleton cylinder (201.1). The metal skeleton cylinder (201.1) includes a skeleton cylinder (201.1a) and a flanged ring (201.1b) disposed at one end of the skeleton cylinder (201.1a). The skeleton cylinder (201.1a) is coaxially arranged with the shift shaft (3), and the flanged ring (201.1b) is coaxially arranged with the shift shaft (3).

3. The shift shaft sealing structure according to claim 2, characterized in that, The connection between the inner section fixing part (401) and the oil seal outer base (201) is outside the metal skeleton cylinder (201.1), the first sealing part is inside the metal skeleton cylinder (201.1), the second sealing part is inside the metal skeleton cylinder (201.1), and the third sealing part is inside the metal skeleton cylinder (201.1).

4. A shift shaft sealing structure according to claim 1, 2, or 3, characterized in that, The middle section elastic cover (402) is provided with an adjusting ring (501) located adjacent to the inner section fixing part (401). The adjusting ring (501) is fixed to the middle section elastic cover (402). The middle section elastic cover (402) is provided with a collar (502) for contacting and pressing the third sealing lip (204). The collar (502) is fixed to the adjusting ring (501) by a number of connecting rods (503). When the adjusting ring (501) contacts the inner section fixing part (401): the collar (502) is in the outer middle ring groove (2b), the collar (502) contacts and squeezes the third sealing lip (204), and the vertical projection of the collar (502) overlaps with the vertical projection of the third sealing part; When the shift shaft (3) is in the middle positioning position: the adjusting ring (501) is separated from the inner section fixing part (401), and the collar (502) is outside the outer middle ring groove (2b).

5. The shift shaft sealing structure according to claim 4, characterized in that, During the entire process of the shift shaft (3) moving from the intermediate positioning position to the inner positioning position, in the axial direction of the shift shaft (3): if the shift shaft (3) moves a distance of 10Y, then the collar (502) moves a distance less than Y.

6. The shift shaft sealing structure according to claim 4, characterized in that, The third sealing lip (204) is provided with a narrow air passage (204a) and a large annular cavity (204b) surrounding the third sealing part. The large annular cavity (204b) is arranged coaxially with the shift shaft (3). One end of the narrow air passage (204a) is connected to the large annular cavity (204b), and the other end of the narrow air passage (204a) is a small opening connected to the outer middle annular groove (2b). When the adjusting ring (501) contacts the inner section fixing part (401): the volume of the large annular cavity (204b) is 0.

7. A shift shaft sealing structure according to claim 1, 2, or 3, characterized in that, The first sealing lip (202) extends away from the second sealing lip (203) toward the inner ring groove (2a) to form a first lip flange (202.1). The inner ring groove (2a) is provided with a spring ring (6) for pressing the first sealing lip (202) onto the shift shaft (3). The first lip flange (202.1) and the spring ring (6) are closely attached to each other. The first lip flange (202.1), the spring ring (6) and the second sealing lip (203) are arranged sequentially along the axial direction of the shift shaft (3).

8. A shift shaft sealing structure according to claim 1, 2, or 3, characterized in that, The main shaft hole (1a) is composed of a small diameter shaft hole (1b) and a large diameter shaft hole (1c). The small diameter shaft hole (1b) and the large diameter shaft hole (1c) are coaxial and connected. One end of the large diameter shaft hole (1c) is connected to the outside of the transmission housing (1). The main oil seal (2) is located on the large diameter shaft hole (1c). A sliding bearing is provided in the small diameter shaft hole (1b). The shift shaft (3) is connected to the sliding bearing and is slidably connected to the small diameter shaft hole (1b) through the sliding bearing.

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