Gearbox

Abstract

The utility model provides a gear box which comprises a gear box shell and a shaft, the shaft is sleeved with the gear box shell, a sealing device is arranged in a radial gap between the gear box shell and the shaft, and the sealing device comprises a framework in a circular ring shape; the sealing part is attached to the framework, the sealing part comprises a sealing inner circumferential axial part, the sealing inner circumferential axial part extends in the axial direction and the circumferential direction of the sealing device, and the sealing inner circumferential axial part is used for forming contact sealing with a shaft; the preloading spring is tightly attached to the radial outer side of the axial part of the sealing inner circumference; and the protective cover is annular, the protective cover is connected to the framework, at least one part of the protective cover is located on the axial inner side of the preloading spring, and at least one part of the protective cover and the preloading spring are located at the same radial position.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vehicle power systems, and particularly relates to a gear box. BACKGROUND

[0002] In one possible technical solution, the sealing device includes a skeleton, a sealing part, a preloaded spring, and a dust lip. Under the driving of high-speed rotation of the gear, the lubricating oil in the gear box will flow at high speed, which may impact the preloaded spring. In some extreme cases, this may cause the preloaded spring to be detached from the installation position. In addition, during the assembly process, other components in the gear box may scratch the sealing part of the sealing device, causing the sealing part to be damaged, or the preloaded spring to be detached from the installation position. CONTENT OF THE UTILITY MODEL

[0003] The present application aims to propose a gear box to solve or alleviate at least one of the defects in the background art.

[0004] Embodiments of the present application propose a gear box, which includes a gear box shell and a shaft, the gear box shell is sleeved on the shaft, a radial gap is provided between the gear box shell and the shaft, and a sealing device is arranged in the radial gap, the sealing device includes:

[0005] a skeleton, the skeleton is in the form of a circular ring;

[0006] a sealing part, the sealing part is attached to the skeleton, the sealing part includes a sealing inner circumferential axial part, the sealing inner circumferential axial part extends along the axial direction and the circumferential direction of the sealing device, and the sealing inner circumferential axial part is used to form a contact seal with the shaft;

[0007] a preloaded spring, the preloaded spring is in close contact with the radial outer side of the sealing inner circumferential axial part; and

[0008] a protective cover, the protective cover is in the form of a ring, the protective cover is connected to the skeleton, at least a part of the protective cover is located on the axial inner side of the preloaded spring, and at least a part of the protective cover and the preloaded spring are located at the same radial position.

[0009] In at least one possible embodiment, the protective cover is formed with a ring-shaped groove with an opening facing the axial inner side, and the groove is capable of allowing the oil to flow.

[0010] In at least one possible embodiment, the inner diameter of the protective cover is greater than the inner diameter of the sealing part, so that there is a gap between the protective cover and the shaft.

[0011] In at least one possible embodiment, the protective cover includes a protective cover outer circumferential axial part, a protective cover radial part, and a protective cover inner circumferential axial part,

[0012] The cover outer peripheral axial portion extends along the axial direction and the peripheral direction of the sealing device, the cover radial portion extends along the radial direction and the peripheral direction of the sealing device, and the cover inner peripheral axial portion extends along the axial direction and the peripheral direction of the sealing device,

[0013] The cover outer peripheral axial portion and the cover inner peripheral axial portion are connected together by the cover radial portion, the cover radial portion is located axially outside the cover outer peripheral axial portion and the cover inner peripheral axial portion, and the cover outer peripheral axial portion is located radially outside the cover inner peripheral axial portion.

[0014] In at least one possible implementation, there is a radial gap between the cover inner peripheral axial portion and the preloaded spring.

[0015] In at least one possible implementation, the cover further comprises a cover inner peripheral portion, the cover inner peripheral portion extending along the radial direction and the peripheral direction of the sealing device,

[0016] The cover inner peripheral portion extends from an axially inner side end of the cover inner peripheral axial portion to a radially inner side, the cover inner peripheral portion being located axially inside the preloaded spring and the sealing inner peripheral axial portion, and the cover inner peripheral portion at least partially covering the preloaded spring and the sealing inner peripheral axial portion from the axially inner side.

[0017] In at least one possible implementation, the cover and the skeleton are fixedly connected by interference fit.

[0018] In at least one possible implementation, the sealing portion further comprises a sealing outer peripheral axial portion and a sealing radial portion, the sealing outer peripheral axial portion extending along the axial direction and the peripheral direction of the sealing device, the sealing radial portion extending along the radial direction and the peripheral direction of the sealing device, the sealing outer peripheral axial portion and the sealing inner peripheral axial portion being connected by the sealing radial portion, the sealing inner peripheral axial portion being provided with a first sealing lip, the first sealing lip extending from an inner peripheral portion of the sealing inner peripheral axial portion towards the radially inner side, and the first sealing lip being used for tightly contacting the outer peripheral surface of the shaft.

[0019] In at least one possible implementation, the preloaded spring and the first sealing lip are in the same axial position, and the preloaded spring is located radially inside the first sealing lip.

[0020] In at least one possible implementation, the gear box further comprises a dust cover, the dust cover being provided axially outside the sealing device, and the dust cover completely covering the sealing device in the radial direction of the sealing device.

[0021] By adopting the above technical scheme, at least a part of the protective cover is located on the inner side of the axial direction of the preloaded spring, thereby protecting the preloaded spring and preventing the preloaded spring from being easily contacted and separated from the mounting position. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A partial structure schematic diagram of a gear box according to an embodiment of the present application is shown.

[0023] Figure 2 A partial enlarged view of Figure 1 is shown.

[0024] Figure 3 A protective cover installation schematic diagram of a sealing device of a gear box according to an embodiment of the present application is shown.

[0025] REFERENCE SIGNS

[0026] 100 sealing device 200 flange 300 gear box shell 400 wave spring 500 dust cover

[0027] 1 skeleton 11 skeleton radial portion 12 skeleton axial portion

[0028] 2 sealing portion 21 first sealing lip 22 second sealing lip 23 third sealing lip 24 sealing outer peripheral axial portion 25 sealing inner peripheral axial portion 26 sealing radial portion

[0029] 3 preloaded spring

[0030] 4 dust lip

[0031] 5 protective cover 51 protective cover outer peripheral axial portion 52 protective cover radial portion 53 protective cover inner peripheral axial portion 54 protective cover inner peripheral portion 55 groove

[0032] G1 first gap

[0033] G2 second gap

[0034] T protective cover installation tool

[0035] A axial direction R radial direction. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the above purposes, features and advantages of the present application, the specific embodiments of the present application are described in detail in this part in conjunction with the drawings. In addition to the various embodiments described in this part, the present application can be implemented in other different ways, and those skilled in the art can make corresponding improvements, modifications and substitutions without departing from the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed in this part. The protection scope of the present application should be subject to the claims.

[0037] In Figures 1 to 3In the figure, A represents the axial direction of the sealing device 100, which is consistent with the axial direction of the gear box; R represents the radial direction of the sealing device, which is consistent with the radial direction of the gear box; the arrow L points to the axial outside (i.e. the outside of the gear box), and the direction opposite to the arrow L is the axial inside (i.e. the inside of the gear box).

[0038] As shown in the figure, the embodiment of the present application proposes a gear box, which comprises a sealing device 100, a shaft (for example, a flange shaft 200), a gear box shell 300, a wave spring 400 and a dust cover 500. Figures 1 to 3

[0039] The gear box shell 300 surrounds the flange shaft 200 in the circumferential direction, the sealing device 100 can be arranged between the flange shaft 200 and the gear box shell 300 which can rotate relative to each other, and the sealing device 100 can seal the gap in the radial direction between the flange shaft 200 and the gear box shell 300 which are sleeved with each other. The axial inside of the sealing device 100 (the right side in the figure, the inside of the gear box) can have lubricating oil, and the axial outside of the sealing device 100 (the left side in the figure, the outside of the gear box) can have water, dust and other contaminants, for example, and the sealing device 100 can be used to prevent the lubricating oil inside the gear box from leaking out and prevent the contaminants from entering the inside of the gear box. Figure 1 Figure 1

[0040] Further, the dust cover 500 can be mounted on the flange shaft 200, and the dust cover 500 can be arranged on the axial outside of the sealing device 100 (the left side in the figure, the outside of the gear box). In the radial direction R, the dust cover 500 can completely cover the sealing device 100, and from the outside of the gear box in the axial direction A, the dust cover 500 completely blocks the sealing device 100, and the sealing device 100 cannot be observed. The dust cover 500 can prevent the contaminants from contacting the sealing device 100, so that the service life of the sealing device 100 is longer. Figure 1 Specifically, the dust cover 500 can comprise an inner diameter axial extension, a radial extension and an outer diameter axial extension. The inner diameter axial extension can extend annularly along the axial direction A and the circumferential direction, the radial extension can extend annularly along the radial direction R and the circumferential direction, and the outer diameter axial extension can extend annularly along the axial direction A and the circumferential direction. The inner diameter axial extension can be connected to the radial inside of the radial extension, and the outer diameter axial extension can be connected to the radial outside of the radial extension. The inner diameter axial extension and the outer diameter axial extension can extend from the radial extension to the same side in the axial direction (for example, the axial inside, the right side in the figure).

[0041] Figure 1

[0042] ​​​​​The wave spring 400 can be located between the flange shaft 200 and the planet carrier, and can provide elastic force after being compressed, thereby supporting the planet carrier to be in a correct working position. Optionally, the flange shaft 200 can have a mounting groove for accommodating the wave spring 400, and the wave spring 400 can be mounted in the mounting groove first, and then the wave spring 400 and the flange shaft 200 are mounted in the gear box housing 300 together.

[0043] The sealing device 100 can include a skeleton 1, a sealing part 2, a preloaded spring 3, a dust lip 4, and a protective cover 5.

[0044] The skeleton 1 can be in a circular ring shape, and can include a skeleton radial part 11 and a skeleton axial part 12. The skeleton radial part 11 can extend along a radial direction R and a circumferential direction of the sealing device 100, and the skeleton axial part 12 can extend along an axial direction A and a circumferential direction of the sealing device 100. The skeleton radial part 11 can be connected to the skeleton axial part 12. The skeleton radial part 11 can be located radially inside (lower side in Figure 2 ) of the skeleton axial part 12, and can be located axially outside (left side in Figure 2 ) of the skeleton axial part 12. The skeleton radial part 11 and the skeleton axial part 12 can be integrally formed, for example, by stamping. The skeleton 1 can be made of a metal material.

[0045] As shown in Figure 2 and Figure 3 , the sealing part 2 can be attached to the skeleton 1. The sealing part 2 can include a first sealing lip 21, a second sealing lip 22, a third sealing lip 23, a sealing outer circumferential axial part 24, a sealing inner circumferential axial part 25, and a sealing radial part 26. The sealing part 2 can be made of rubber.

[0046] The sealing outer circumferential axial part 24 can extend along the axial direction A and the circumferential direction of the sealing device 100, the sealing inner circumferential axial part 25 can extend along the axial direction A and the circumferential direction of the sealing device 100, and the sealing radial part 26 can extend along the radial direction R and the circumferential direction of the sealing device 100. The sealing outer circumferential axial part 24 and the sealing inner circumferential axial part 25 can be connected through the sealing radial part 26, and the sealing radial part 26 can be located axially outside (left side in Figure 2 ) of the sealing outer circumferential axial part 24 and the sealing inner circumferential axial part 25. The sealing outer circumferential axial part 24 can be connected to a radially outer side part (upper side part in Figure 2 ) of the sealing radial part 26, and the sealing inner circumferential axial part 25 can be connected to a radially inner side part (lower side part in Figure 2 ) of the sealing radial part 26. The sealing outer circumferential axial part 24, the sealing inner circumferential axial part 25, and the sealing radial part 26 can have a C-shaped cross section as a whole.

[0047] The sealing outer axial portion 24 can be attached to the radially outer side of the skeleton axial portion 12, and the sealing outer axial portion 24 can be supported by the skeleton axial portion 12. The sealing outer axial portion 24 can contact and engage with the gearbox housing 300. The sealing radial portion 26 can be attached to the axially outer side of the skeleton radial portion 11, and the sealing radial portion 26 can be supported by the skeleton radial portion 11. The sealing inner axial portion 25 can be located radially inner of the skeleton axial portion 12. The sealing inner axial portion 25 and the skeleton axial portion 12 can be spaced apart by a certain distance.

[0048] The first sealing lip 21 can be connected to the axial portion 25 of the inner circumference of the seal, and the first sealing lip 21 can extend from the inner circumference of the axial portion 25 of the inner circumference of the seal toward the radially inward side. Figure 2 The first sealing lip 21 extends to the lower side of the flange shaft 200. It can make close contact with the outer peripheral surface of the flange shaft 200, thereby keeping the sealing device 100 and the flange shaft 200 sealed.

[0049] The second sealing lip 22 can be connected to the axial portion 25 of the sealing inner circumference (or, the second sealing lip 22 can be connected to the transition portion between the axial portion 25 of the sealing inner circumference and the radial portion 26 of the sealing). The second sealing lip 22 can extend radially inward from the axial portion 25 of the sealing inner circumference (or the transition portion between the axial portion 25 of the sealing inner circumference and the radial portion 26). Figure 2 It extends from the lower side of the middle and towards the axially outer side. Figure 2 The second sealing lip 22 is tilted to the left. The inner diameter of the second sealing lip 22 can be larger than the inner diameter of the first sealing lip 21, so that the second sealing lip 22 can be separated from the outer peripheral surface of the flange shaft 200 by a certain distance.

[0050] The third sealing lip 23 can be connected to the sealing radial portion 26, and the third sealing lip 23 can extend from the sealing radial portion 26 toward the axially outward side ( Figure 2 Extending to the left of the middle) and towards the radially outward ( Figure 2 (The upper side of the middle) is tilted.

[0051] The preload spring 3 can be tightly attached to the radially outer side of the axial portion 25 of the sealing inner circumference. The preload spring 3 can be annular and compresses the axial portion 25 of the sealing inner circumference, applying a radially inward force to the axial portion 25 of the sealing inner circumference, so that the first sealing lip 21 can tightly adhere to the flange shaft 200 being sealed. Furthermore, the preload spring 3 can be located in the same axial position as the first sealing lip 21, and the preload spring 3 can be located radially outer of the first sealing lip 21. An annular groove can be provided on the outer circumference of the axial portion 25 of the sealing inner circumference, and the preload spring 3 can be embedded in the annular groove, making it difficult for the preload spring 3 to move relative to the axial portion 25 of the sealing inner circumference.

[0052] The dust lip 4 can be connected (e.g., bonded) to the axial outer side of the sealing part 2. Figure 2The inner diameter of the dust lip 4 can be smaller than the inner diameter of the second sealing lip 22, the inner circumferential surface of the dust lip 4 can contact the flange shaft 200, so that the dust lip 4 can protect the second sealing lip 22 and can block a part of the external contaminants from directly contacting the second sealing lip 22. The dust lip 4 can be made of felt material.

[0053] The protective cover 5 can be connected to the skeleton 1, the protective cover 5 can be fixedly installed on the skeleton axial portion 12 by interference fit for example, the protective cover 5 can be a circular ring, and the protective cover 5 can be located on the radially inner side of the skeleton axial portion 12. It can be understood that here, the protective cover 5 and the skeleton axial portion 12 can have a material (such as rubber) of the sealing portion 2 therebetween. At least a part of the protective cover 5 can be located on the axially inner side of the preloaded spring 3, so as to protect the preloaded spring 3 and make the preloaded spring 3 not easy to be contacted to be disengaged from the installed position.

[0054] Optionally, at least a part of the protective cover 5 and the preloaded spring 3 are at the same radial position, and the protective cover 5 is located on the axially inner side of the preloaded spring 3, so that the other components in the gearbox can be prevented from scratching the sealing portion 2, the other components in the gearbox can be prevented from contacting the preloaded spring 3, and the lubricating oil can be prevented from impacting the preloaded spring 3, thereby preventing the preloaded spring 3 from being disengaged from the installed position.

[0055] Specifically, the protective cover 5 can include a protective cover outer circumferential axial portion 51, a protective cover radial portion 52, a protective cover inner circumferential axial portion 53, and a protective cover inner circumferential portion 54.

[0056] The protective cover outer circumferential axial portion 51 can extend along the axial direction A and the circumferential direction of the sealing device 100, the protective cover radial portion 52 can extend along the radial direction R and the circumferential direction of the sealing device 100, and the protective cover inner circumferential axial portion 53 can extend along the axial direction A and the circumferential direction of the sealing device 100. The protective cover outer circumferential axial portion 51 and the protective cover inner circumferential axial portion 53 are connected together through the protective cover radial portion 52. The protective cover outer circumferential axial portion 51 and the protective cover inner circumferential axial portion 53 can be parallel (including substantially parallel), the protective cover outer circumferential axial portion 51 is located on the radially outer side of the protective cover inner circumferential axial portion 53, and the protective cover radial portion 52 can be located on the axially outer side of the protective cover outer circumferential axial portion 51 and the protective cover inner circumferential axial portion 53 (the left end in the figure). Figure 2 The cross sections of the protective cover outer circumferential axial portion 51, the protective cover radial portion 52, and the protective cover inner circumferential axial portion 53 can be C-shaped as a whole. The protective cover outer circumferential axial portion 51, the protective cover radial portion 52, and the protective cover inner circumferential axial portion 53 can surround an annular groove 55, and the lubricating oil can flow through the annular groove 55, for example, the lubricating oil can enter the annular groove 55 from the radially outer side of the annular groove 55 and then flow out of the annular groove 55 from the radially inner side of the annular groove 55.

[0057] A radial gap (first gap G1) exists between the inner peripheral axial portion 53 of the protective cover and the pre-load spring 3.

[0058] The inner peripheral portion 54 of the protective cover can extend in the radial direction R and the circumferential direction of the sealing device 100, the inner peripheral portion 54 of the protective cover can be connected to the inner peripheral axial portion 53 of the protective cover, and the inner peripheral portion 54 of the protective cover can be located at the axially inner side end (right end in Figure 2

[0059] The inner peripheral portion 54 of the protective cover can be located at the axially inner side (right side in Figure 2 The inner peripheral portion 54 of the protective cover can extend from the axially inner side of the inner peripheral axial portion 53 to the radially inner side, and the inner peripheral portion 54 of the protective cover can at least partially cover the pre-load spring 3 and the inner peripheral axial portion 25 of the sealing portion from the axially inner side. Thus, the pre-load spring 3 and the inner peripheral axial portion 25 of the sealing portion are not easily contacted by other components, and the lubricating oil can also be blocked by the protective cover 5, so that the pre-load spring 3 is not easily directly impacted.

[0060] As shown in Figs. Figure 3 and Figure 2 viewed from the axially inner side (right side in Figure 3 , Figure 2 The pre-load spring 3 can be completely covered by the inner peripheral axial portion 25 of the sealing portion and the inner peripheral portion 54 of the protective cover, so that the pre-load spring 3 cannot be seen. In this way, other components are not easily contacted with the pre-load spring 3 from the axially inner side.

[0061] The inner diameter of the protective cover 5 is greater than the inner diameter of the first sealing lip 21 of the sealing portion 2, that is, the inner peripheral surface of the inner peripheral portion 54 of the protective cover is located at the radially outer side of the first sealing lip 21 of the sealing portion 2, so that a gap (second gap G2) exists between the protective cover 5 and the flange shaft 200.

[0062] As shown in Figs. ​ and 3 The outer peripheral axial portion 51 of the protective cover and the skeleton axial portion 12 can be parallel (including substantially parallel) and tightly fit together with interference. It can be understood that the protective cover 5 and the skeleton axial portion 12 can have the material (such as rubber) of the sealing portion 2 therebetween. When the protective cover 5 is installed, the protective cover 5 is pressed from the axially inner side to the radially inner side of the skeleton axial portion 12 using the protective cover installation tool T, so that the protective cover 5 is connected to the skeleton 1.

[0063] The protective cover 5 can avoid the influence of the lubricating oil flowing at high speed and other components (such as the wave spring 400) on the pre-load spring 3, avoid the pre-load spring 3 from being out of the correct installation position, and protect the sealing portion 2, especially avoid the inner peripheral axial portion 25 of the sealing portion from being scratched or even damaged by other components.

[0064] ​It should be understood that at least part or a feature of the above-described embodiments, examples, or aspects can be appropriately combined.

[0065] It can be understood that, in the present application, when the number of components or members is not particularly limited, the number can be one or more, and the plurality herein refers to two or more. For the case where the number of components or members is described as a specific number, such as two, three, four, etc. in the drawings and / or the description, the specific number is generally exemplary and not limiting, and it can be understood as a plurality, i.e., two or more, but this does not mean that the present application excludes the case of one.

[0066] In the present application, unless otherwise explicitly stated or limited, the terms "mounting", "assembly", "assembly", "connection", "connection", "coupling", "connection", "abutment", "communication", "communication", "conduction", "fixing", "fastening", and the like should be understood broadly, for example, it can be direct or indirect. For example, in terms of connection, it can be a fixed connection, or a detachable connection, or integrated; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication or interaction relationship between two elements, unless otherwise explicitly stated or limited. For example, in terms of communication / conduction, etc., it can be direct communication / conduction, or indirect communication / conduction via an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0067] In the present application, unless otherwise explicitly stated or limited, one member is disposed in / installed in / located in / contained in / placed in another member, etc. can be either of the following two cases: a part or most of the one member is located within the other member; and the one member is completely contained within the other member.

[0068] Although the present application has been described in detail using the above-described embodiments, it is clear to those skilled in the art that the present application is not limited to the embodiments described in the present specification. The present application can be modified and implemented as a modified embodiment without departing from the spirit and scope of the present application defined by the claims. Therefore, the description in the present specification is for the purpose of example and does not have any limiting meaning on the present application.

Claims

1. A gear box comprising a gear box housing and a shaft, the gear box housing being sleeved on the shaft, a radial gap between the gear box housing and the shaft being provided with a sealing device, characterized in that, The sealing device comprises: a skeleton in the shape of a ring; a sealing part attached to the skeleton, the sealing part comprising a sealing inner peripheral axial part extending in the axial and peripheral directions of the sealing device, the sealing inner peripheral axial part being used to form a contact seal with the shaft; a preloaded spring located radially outward of the sealing inner peripheral axial part; and a protective cover in the shape of a ring, the protective cover being connected to the skeleton, at least a portion of the protective cover being located axially inward of the preloaded spring, at least a portion of the protective cover and the preloaded spring being located at the same radial position.

2. The gear case of claim 1, wherein, The protective cover is formed with a ring-shaped groove having an opening facing axially inward, the groove being capable of allowing oil to flow.

3. The gear case of claim 1, wherein, The inner diameter of the protective cover is larger than the inner diameter of the sealing part, so that a gap exists between the protective cover and the shaft.

4. The gear case of claim 1, wherein, The protective cover comprises a protective cover outer peripheral axial part, a protective cover radial part, and a protective cover inner peripheral axial part, the protective cover outer peripheral axial part extending in the axial and peripheral directions of the sealing device, the protective cover radial part extending in the radial and peripheral directions of the sealing device, the protective cover inner peripheral axial part extending in the axial and peripheral directions of the sealing device, the protective cover outer peripheral axial part and the protective cover inner peripheral axial part being connected together by the protective cover radial part, the protective cover radial part being located axially outward of the protective cover outer peripheral axial part and the protective cover inner peripheral axial part, the protective cover outer peripheral axial part being located radially outward of the protective cover inner peripheral axial part.

5. The gear case of claim 4, wherein, A radial gap exists between the protective cover inner peripheral axial part and the preloaded spring.

6. The gear case of claim 4, wherein, The protective cover further comprises a protective cover inner peripheral part extending in the radial and peripheral directions of the sealing device, the protective cover inner peripheral part extending radially inward from an axially inward end of the protective cover inner peripheral axial part, the protective cover inner peripheral part being located axially inward of the preloaded spring and the sealing inner peripheral axial part, the protective cover inner peripheral part at least partially covering the preloaded spring and the sealing inner peripheral axial part from the axially inward side.

7. The gear case of claim 1, wherein, The protective cover and the skeleton are fixedly connected by an interference fit.

8. The gear case of claim 1, wherein, The sealing part further comprises a sealing outer peripheral axial part extending in the axial and peripheral directions of the sealing device, and a sealing radial part extending in the radial and peripheral directions of the sealing device, the sealing outer peripheral axial part and the sealing inner peripheral axial part being connected by the sealing radial part, the sealing inner peripheral axial part being provided with a first sealing lip extending radially inward from an inner peripheral part of the sealing inner peripheral axial part, the first sealing lip being used to make close contact with the outer peripheral surface of the shaft.

9. The gear case of claim 8, wherein, The preloaded spring and the first sealing lip are located at the same axial position, the preloaded spring being located radially inward of the first sealing lip.

10. The gear case of claim 1, wherein, The gear box further comprises a dust cover, the dust cover being located axially outward of the sealing device, the dust cover completely covering the sealing device in the radial direction of the sealing device.

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