CN220374187U - Maintenance-free wheel rim assembly for axle - Google Patents

Abstract

The application provides a maintenance-free wheel limit assembly for axle relates to automobile parts technical field. The maintenance-free wheel rim assembly for the axle comprises a hub, a bearing unit and a spacer bush, wherein the hub is provided with a mounting through hole; the bearing unit comprises an outer supporting ring, an inner supporting ring, an outer bearing and an inner bearing, and the outer bearing, the outer supporting ring, the inner supporting ring and the inner bearing are sequentially arranged in the mounting through hole along the axial direction of the mounting through hole; the spacer bush is inserted on the outer support ring and the inner support ring, and is positioned between the outer bearing and the inner bearing. The maintenance-free wheel rim assembly for the axle provided by the application can achieve design clearance without adjusting bearing clearance, improves the service life of the bearing, reduces the consumption of lubricating grease, and has the advantage of no maintenance.

Description

Maintenance-free wheel rim assembly for axle

Technical Field

The application relates to the technical field of automobile parts, in particular to a maintenance-free wheel rim assembly for an axle.

Background

The automobile wheel assembly has the function of reducing the rotation speed and torque transmitted by the main speed reducer, increasing the torque, transmitting the rotation speed and torque to the wheels, and improving the transmission efficiency, so that the wheels generate larger driving force under the reaction of the ground adhesion force, and the stress of all parts in front of the wheel assembly is reduced. Among them, the hub bearing is one of the key parts of the automobile, and its main function is to carry weight and provide accurate guidance for the rotation of the hub.

In the prior art, an axle wheel assembly generally consists of a hub, tapered roller bearings on two sides and an inner oil seal, and the clearance adjustment of the bearings is realized by adopting a method of screwing nuts and then backing back for a certain angle.

However, when the existing automobile hub is installed, the clearance of the bearing is adjusted by an installer, so that the bearing is difficult to maintain in an optimal clearance state after being installed, the using amount of lubricating grease is large, the service life of the bearing is influenced by impurities generated by abrasion, and periodic maintenance is needed.

Disclosure of Invention

In order to solve the above-mentioned problem in the prior art, the present application provides a maintenance-free wheel rim assembly for an axle.

The maintenance-free wheel rim assembly for the axle comprises a hub, a bearing unit and a spacer bush, wherein the hub is provided with a mounting through hole; the bearing unit comprises an outer supporting ring, an inner supporting ring, an outer bearing and an inner bearing, and the outer bearing, the outer supporting ring, the inner supporting ring and the inner bearing are sequentially arranged in the mounting through hole along the axial direction of the mounting through hole; the spacer bush is inserted on the outer support ring and the inner support ring, and is positioned between the outer bearing and the inner bearing.

In one possible implementation, the maintenance-free wheel rim assembly for the axle provided by the application has the outer side wall of the spacer sleeve in clearance fit with the inner side wall of the inner support ring and the inner side wall of the outer support ring.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle provided by the application is provided with a guide chamfer at one end of the spacer facing the inner bearing, and the guide chamfer is positioned on the inner wall of the spacer.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle is provided with an outer support ring mounting surface, an inner support ring mounting surface, an outer bearing mounting surface and an inner bearing mounting surface on the inner wall of the mounting through hole along the axial direction of the mounting through hole, wherein the outer support ring, the inner support ring, the outer bearing and the inner bearing are respectively in corresponding abutting connection with the outer support ring mounting surface, the inner support ring mounting surface, the outer bearing mounting surface and the inner bearing mounting surface; a containing cavity is arranged between the inner wall of the mounting through hole and the outer side wall of the spacer bush; the number of the spacers is at least one, and a deformation ring is arranged in the middle of one spacer and protrudes towards the accommodating cavity.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle provided by the application is characterized in that the bearing unit further comprises a sealing ring, a thrust washer and an outer clamping spring which are sequentially arranged, the sealing ring is located on the outer side of the outer bearing, and the outer clamping spring is clamped with the mounting through hole.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle is provided, and the inner diameter of the sealing ring is in clearance fit or interference fit with the outer diameter of the inner ring of the outer bearing; the radial space between the thrust washer and the sealing ring and the axial space between the thrust washer and the outer clamping spring are clearance fit to form labyrinth seal for the outer bearing.

In one possible implementation, the maintenance-free wheel rim assembly for the axle provided by the application is provided, and a first oil storage groove is formed between the outer support ring and the sealing ring.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle provided by the application is characterized in that the bearing unit further comprises an inner retainer ring, an inner retainer spring and an oil seal, wherein the inner retainer ring is positioned on the inner side of the inner bearing, and the inner retainer spring is clamped with the mounting through hole.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle is provided with the inner retainer ring, wherein the inner retainer ring is provided with a support section, and the support section is abutted with the outer diameter of the inner ring of the inner bearing; the external diameter of the inner support ring is in clearance fit with the inner side wall of the mounting through hole and the inner clamping spring.

In one possible implementation manner, the maintenance-free wheel rim assembly for the axle is provided with a second oil storage groove formed between the inner support ring and the inner check ring.

The application provides a maintenance-free wheel limit assembly for axle through set up the installation through-hole on wheel hub to with the outer bearing of bearing unit, outer support ring, interior supporting ring and interior bearing place in proper order in wheel hub's installation through-hole along the axial of installation through-hole, then through inserting on outer support ring and interior supporting ring and be equipped with the spacer, and the spacer is located between outer bearing and the interior bearing, spacer and outer support ring and interior supporting ring form clearance fit, then screw up lock nut, can reach the design play between interior bearing and the outer bearing, improved the life of bearing, reduced the quantity of lubricating grease, have the advantage that need not to maintain.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings that are needed in the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic structural diagram of a maintenance-free wheel rim assembly for an axle according to an embodiment of the present disclosure;

FIG. 2 is a schematic view of the hub of FIG. 1;

fig. 3 is a schematic view of the spacer in fig. 1.

Specific embodiments thereof have been shown by way of example in the drawings and will herein be described in more detail. These drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments.

Reference numerals illustrate:

100: a hub;

101: mounting through holes;

1011: an outer support ring mounting surface;

1012: an inner support ring mounting surface;

1013: an outer bearing mounting surface;

1014: an inner bearing mounting surface;

200: a bearing unit;

201: an outer support ring;

202: an inner support ring;

203: an outer bearing;

204: an inner bearing;

205: a seal ring;

206: a thrust washer;

207: an outer clamp spring;

208: an oil seal;

209: an inner retainer ring;

2091: a support section;

210: an inner clamp spring;

300: a spacer bush;

301: guiding chamfering;

302: a deformation ring;

400: a receiving chamber.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the preferred embodiments of the present application. It is apparent that the described embodiments are only a part of the embodiments of the present application, not all of the embodiments, and all other embodiments obtained by a person having ordinary skill in the art without making creative efforts based on the embodiments in the present application are within the scope of protection of the present application.

It should be noted that, in the description of the embodiments of the present application, terms such as "upper," "lower," "inner," "outer," and terms of orientation or positional relationship are based on the directions or positional relationships shown in the drawings, and are merely for convenience of description, and do not indicate or imply that the apparatus or component must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present application.

Furthermore, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby a feature defining "first," "second," or the like may explicitly or implicitly include one or more such features, and in the description of this application, a "plurality" means two or more unless otherwise specifically limited.

In this application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may communicate with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

The automobile wheel assembly has the function of reducing the rotation speed and torque transmitted by the main speed reducer, increasing the torque, transmitting the rotation speed and torque to the wheels, and improving the transmission efficiency, so that the wheels generate larger driving force under the reaction of the ground adhesion force, and the stress of all parts in front of the wheel assembly is reduced. Among them, the hub bearing is one of the key parts of the automobile, and its main function is to carry weight and provide accurate guidance for the rotation of the hub. In the prior art, an axle wheel assembly generally consists of a hub, tapered roller bearings on two sides and an inner oil seal, and the clearance adjustment of the bearings is realized by adopting a method of screwing nuts and then backing back for a certain angle. However, when the existing automobile hub is installed, the clearance of the bearing is adjusted by an installer, so that the bearing is difficult to maintain in an optimal clearance state after being installed, the using amount of lubricating grease is large, the service life of the bearing is influenced by impurities generated by abrasion, and periodic maintenance is needed.

In view of this, this application provides a maintenance-free wheel limit assembly for axle, through set up the installation through-hole on wheel hub, with the outer bearing of bearing unit, outer support ring, interior support ring and interior bearing place in proper order in wheel hub's installation through-hole along the axial of installation through-hole, then through inserting on outer support ring and interior support ring and be equipped with the spacer, and the spacer is located between outer bearing and the interior bearing, spacer and outer support ring and interior support ring form clearance fit, then screw up lock nut, can reach the design play between interior bearing and the outer bearing, the life of bearing has been improved, the quantity of lubricating grease has been reduced, the advantage that has not need to maintain.

The present application will now be described in detail with reference to the accompanying drawings and specific examples.

Referring to fig. 1, the maintenance-free wheel rim assembly for an axle provided by the application comprises a wheel hub 100, a bearing unit 200 and a spacer 300, wherein the wheel hub 100 is provided with a mounting through hole 101; the bearing unit 200 includes an outer support ring 201, an inner support ring 202, an outer bearing 203, and an inner bearing 204, the outer bearing 203, the outer support ring 201, the inner support ring 202, and the inner bearing 204 being sequentially disposed in the mounting through hole 101 in the axial direction of the mounting through hole 101; spacer 300 is interposed between outer support ring 201 and inner support ring 202, and spacer 300 is located between outer bearing 203 and inner bearing 204.

In this application, in order to place the bearing unit 200 in the hub 100, the hub 100 is provided with the mounting through hole 101.

Wherein the bearing unit 200 includes an outer support ring 201, an inner support ring 202, an outer bearing 203, and an inner bearing 204, and is fitted into the mounting through hole 101 in the axial direction of the mounting through hole 101 in the order of the outer bearing 203, the outer support ring 201, the inner support ring 202, and the inner bearing 204 when the fitting is performed.

During use, the outer support ring 201 and the inner support ring 202 can play a role in supporting the spacer 300, so that the spacer 300 between the outer bearing 203 and the inner bearing 204 is ensured to be coaxial with the inner rings of the outer bearing 203 and the inner bearing 204, and assembly is facilitated.

The outer support ring 201 and the inner support ring 202 may be made of nylon material, so that the outer support ring 201 and the inner support ring 202 are easy to process, mechanical parts made of nylon material have self-lubricity, noise is low in use, and the nylon material has the advantages of good oil resistance and light weight.

In some embodiments, the spacer 300 is inserted on the outer support ring 201 and the inner support ring 202, and then the tightening torque conforming to the specification, the type and the like of the tightening nut is used to tighten the tightening nut, so that the pretension of the inner bearing 204 and the outer bearing 203 is realized, the later play of the inner bearing 204 and the outer bearing 203 is not required to be adjusted, the service life is prevented from being influenced by the adjustment play, and the bearing unit 200 is pre-coated with lubricating grease, the lubricating grease is not leaked in the use process, so that the lubricating grease is not required to be added, and the design is adopted, so that the use amount of the lubricating grease is effectively reduced, and the maintenance-free advantage is realized.

Referring to fig. 1, in the present embodiment, the outer sidewall of spacer 300 is in clearance fit with the inner sidewall of inner support ring 202 and the inner sidewall of outer support ring 201.

During assembly, the spacer 300 is inserted into the outer support ring 201 and the inner support ring 202, so that the outer side wall of the spacer 300 and the inner side wall of the inner support ring 202 and the inner side wall of the outer support ring 201 automatically form clearance fit, and the design play is achieved without adjustment after the locking nut is screwed according to the specification.

It will be appreciated that the design play is also the design gap between the outer bearing 203 and the inner bearing 204.

It can be appreciated that the spacer 300 forms a clearance fit with the inner support ring 202 and the outer support ring 201, so that the spacer 300 has no relative friction with the inner support ring 202 and the outer support ring 201, and friction damage between the spacer 300 and the inner support ring 202 and between the spacer 300 and the outer support ring 201 caused by relative friction can be effectively avoided in the use process, thereby improving the service life.

Referring to fig. 1, in the embodiment of the present application, the end of the spacer 300 facing the inner bearing 204 is provided with a guiding chamfer 301, the guiding chamfer 301 being located on the inner wall of the spacer 300.

In a specific implementation, the spacer 300 is provided with a guide chamfer 301 in order to achieve adequate lubrication of the bearing.

It will be appreciated that the guide chamfer 301 is provided at the end of the spacer 300 facing the inner bearing 204, and the guide chamfer 301 is provided on the inner wall of the spacer 300, so that the bearing can be sufficiently lubricated during use, thereby effectively improving the service life of the bearing and reducing the amount of grease used.

Referring to fig. 1, 2 and 3, in the present embodiment, an outer support ring mounting surface 1011, an inner support ring mounting surface 1012, an outer bearing mounting surface 1013 and an inner bearing mounting surface 1014 are provided on the inner wall of the mounting through hole 101 in the axial direction of the mounting through hole 101, and an outer support ring 201, an inner support ring 202, an outer bearing 203 and an inner bearing 204 are respectively abutted against the outer support ring mounting surface 1011, the inner support ring mounting surface 1012, the outer bearing mounting surface 1013 and the inner bearing mounting surface 1014; a containing cavity 400 is arranged between the inner wall of the mounting through hole 101 and the outer side wall of the spacer bush 300; the number of spacers 300 is at least one, and a deformation ring 302 is provided on the middle of one of the spacers 300, the deformation ring 302 protruding toward the receiving chamber 400.

In some embodiments, to limit the mounting of the outer support ring 201, the inner support ring 202, the outer bearing 203, and the inner bearing 204 within the mounting through hole 101, an outer support ring mounting surface 1011, an inner support ring mounting surface 1012, an outer bearing mounting surface 1013, and an inner bearing mounting surface 1014 are provided on the inner wall of the mounting through hole 101 in the axial direction of the mounting through hole 101, whereby, when assembled, the outer support ring 201 abuts against the outer support ring mounting surface 1011, the inner support ring 202 abuts against the inner support ring mounting surface 1012, the outer bearing 203 abuts against the outer bearing mounting surface 1013, and the inner bearing 204 abuts against the inner bearing mounting surface 1014.

It can be appreciated that, through the corresponding butt of the outer support ring 201, the inner support ring 202, the outer bearing 203 and the inner bearing 204 with the outer support ring mounting surface 1011, the inner support ring mounting surface 1012, the outer bearing mounting surface 1013 and the inner bearing mounting surface 1014 respectively, after the locking nut is screwed down according to the specified screwing torque, the design play can be achieved, so that in the later use process, the staff does not need to adjust the play any more, the bad influence of the error of the manual adjustment play on the service life of the bearing is avoided, and the service life of the bearing is effectively improved.

Wherein, the number of the spacers 300 is at least one, and in a specific implementation, the spacers 300 can be spacer groups, and when assembling, spacers 300 with proper axial dimensions are selected to be inserted on the outer support ring 201 and the inner support ring 202.

It can be understood that the middle part of the spacer 300 is provided with a deformation ring 302, the deformation ring 302 protrudes towards the accommodating cavity 400, after the parts are assembled, the locking nut is only required to be screwed down according to a specified screwing torque, and the pre-tightening of the bearing can be realized through the deformation of the deformation ring 302 of the spacer 300.

Referring to fig. 1, in the embodiment of the present application, the bearing unit 200 further includes a seal ring 205, a thrust washer 206, and an outer clip spring 207, which are sequentially disposed, the seal ring 205 is located at the outer side of the outer bearing 203, and the outer clip spring 207 is snapped with the mounting through hole 101.

Wherein, be provided with sealing ring 205 in the outside of outer bearing 203, sealing ring 205 has sealed effect, in the use, can effectively prevent the leakage of lubricating grease, need not to add the lubricating grease any more in the use, has reduced the quantity of lubricating grease.

In this application, sealing ring 205, thrust washer 206 and outer clamping spring 207 are disposed in order outside of outer bearing 203, thrust washer 206 has a limiting effect, and the outer clamping spring clamped with mounting through hole 101 can axially position thrust washer 206.

It can be appreciated that after the seal ring 205, the thrust washer 206 and the outer clamp spring 207 are assembled in sequence on the outer side of the outer bearing 203, a lock nut on the outer side of the outer bearing 203 is screwed according to a specified screwing torque, and the lock nut abuts against one surface of the thrust washer 206 away from the outer bearing 203, so that pretensioning of the inner bearing 204 and the outer bearing 203 is realized.

Referring to FIG. 1, in an embodiment of the present application, there is a clearance or interference fit between the inner diameter of seal ring 205 and the outer diameter of the inner race of outer bearing 203; the radial space between the thrust washer 206 and the sealing ring 205, and the axial space between the thrust washer 206 and the outer clamp spring 207 are clearance fit to form a labyrinth seal for the outer bearing 203.

In this application, clearance fit may be provided between the inner diameter of seal ring 205 and the outer diameter of the inner race of outer bearing 203, whereby seal ring 205 and outer bearing 203 have no relative friction, which may improve service life.

The inner diameter of the sealing ring 205 and the outer diameter of the inner ring of the outer bearing 203 can be in interference fit, so that the sealing ring 205 can support the outer bearing 203 to prevent the outer bearing 203 from slipping.

Wherein, during the assembly, the radial direction between thrust washer 206 and sealing ring 205 is clearance fit, simultaneously, the axial direction between thrust washer 206 and outer clamping spring 207 is also clearance fit, from this, during the use, there is not relative friction between thrust washer 206 and sealing ring 205 and outer clamping spring 207, can improve thrust washer 206, sealing ring 205 and outer clamping spring 207's life.

It will be appreciated that by the clearance fit between the thrust washer 206 and the seal ring 205 and outer clip 207, a labyrinth seal is formed against the outer bearing 203, preventing leakage of grease.

Referring to fig. 1, in the embodiment of the present application, a first oil reservoir is formed between an outer support ring 201 and a seal ring 205.

In particular, when assembling, a first oil reservoir is formed between the outer support ring 201 and the seal ring 205, and thus, grease is filled between the outer support ring 201 and the seal ring 205, and the amount of grease used is small.

It will be appreciated that the seal ring 205 has a sealing effect, and can effectively prevent leakage of grease during use, and no further grease is required during use, thereby further reducing the amount of grease used.

Referring to fig. 1, in the embodiment of the present application, the bearing unit 200 further includes an inner retainer ring 209, an inner clamping spring 210 and an oil seal 208 that are sequentially disposed, where the inner retainer ring 209 is located on the inner side of the inner bearing 204, and the inner clamping spring 210 is clamped with the mounting through hole 101.

In some embodiments, the inner retainer ring 209 is disposed on the inner side of the inner bearing 204, where the inner retainer ring 209 has a sealing function, and can effectively prevent leakage of grease during use.

The oil seal 208 has a sealing function, so that leakage of lubricating grease can be further prevented, the lubricating grease is not required to be added in the use process, and the use amount of the lubricating grease is reduced.

In this application, the inner retainer 209 also has a positioning function, and the inner retainer 209, the inner retainer 210 and the oil seal 208 are sequentially disposed inside the inner bearing 204, so that the inner retainer 209 can be axially positioned by the inner clamp spring 210 clamped with the mounting through hole 101.

It can be understood that the outer clamping spring 207 is clamped with the mounting through hole 101, the inner clamping spring 210 is also clamped with the mounting through hole 101, the outer clamping spring 207 and the inner clamping spring 210 are positioned at two ends of the mounting through hole 101, the outer clamping spring 207 and the inner clamping spring 210 play a role in axial positioning, and when the outer clamping spring 207 and the inner clamping spring 210 are assembled, the outer bearing 203, the outer supporting ring 201, the spacer bush 300, the inner supporting ring 202 and the inner bearing 204 form an integral body which cannot be separated under the axial positioning of the outer clamping spring 207 and the inner clamping spring 210, and after the locking nut is screwed down according to the specification, the designed play is achieved without adjusting the play and the back locking nut is not needed.

When the friction plate is replaced, the wheel rim assembly is pulled out as a whole under the axial positioning of the outer clamping spring 207 and the inner clamping spring 210, the play between the outer bearing 203 and the inner bearing 204 is not affected, and the leakage of lubricating grease is not caused, so that the assembly and the disassembly are convenient.

Referring to fig. 1, in the embodiment of the present application, the inner retainer ring 209 is provided with a support section 2091, the support section 2091 abutting against the outer diameter of the inner ring of the inner bearing 204; the outer diameter of the inner support ring 202 is in clearance fit with the inner side wall of the mounting through hole 101 and the inner clip 210.

In this application, the inner retainer 209 has a positioning function, and a support section 2091 is provided on the inner retainer, and is used to limit the inner bearing 204 when assembling, and the support section 2091 is supported on the outer diameter of the inner ring of the inner bearing 204.

It will be appreciated that the outer diameter of the inner support ring 202 is in clearance fit with the inner side wall of the mounting through hole 101 and the inner clamp spring 210, so that no relative friction exists between the inner support ring 202 and the mounting through hole 101 and the inner clamp spring 210, and friction damage of the inner support ring 202 and the mounting through hole 101 and the inner clamp spring 210 caused by relative friction can be prevented during use.

Wherein, clearance fit between the external diameter of the inner support ring 202 and the inner side wall of the mounting through hole 101 and the inner clip spring 210 can also play a role of sealing, and leakage of grease can be effectively prevented.

Referring to fig. 1, in the embodiment of the present application, a second oil reservoir is formed between the inner support ring 202 and the inner retainer ring 209.

In some embodiments, a second oil storage groove is formed between the inner support ring 202 and the inner retainer ring 209 when assembling, it is understood that grease can be filled between the inner support ring 202 and the inner retainer ring 209 when assembling, and the normal use of the bearing unit 200 can be ensured while the amount of grease is small.

It can be appreciated that the inner retainer ring 209 has positioning and sealing functions, so that the leakage of the grease can be effectively prevented in the use process, and the grease is not required to be added in the use process, so that the use amount of the grease is further reduced.

To sum up, the application provides a maintenance-free wheel limit assembly for axle through set up the installation through-hole on wheel hub, with the outer bearing of bearing unit, outer supporting ring, interior supporting ring and interior bearing place in proper order in wheel hub's installation through-hole along the axial of installation through-hole, then through inserting on outer supporting ring and interior supporting ring and be equipped with the spacer, and the spacer is located between outer bearing and the interior bearing, spacer and outer supporting ring and interior supporting ring form clearance fit, then screw up lock nut, can reach the design play between interior bearing and the outer bearing, the life of bearing has been improved, the quantity of lubricating grease has been reduced, the advantage that has not need to maintain.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand; the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. The maintenance-free wheel rim assembly for the axle is characterized by comprising a wheel hub, a bearing unit and a spacer bush, wherein the wheel hub is provided with a mounting through hole;

the bearing unit comprises an outer supporting ring, an inner supporting ring, an outer bearing and an inner bearing, and the outer bearing, the outer supporting ring, the inner supporting ring and the inner bearing are sequentially arranged in the mounting through hole along the axial direction of the mounting through hole;

the spacer bush is inserted on the outer support ring and the inner support ring, and is positioned between the outer bearing and the inner bearing.

2. The maintenance-free wheel rim assembly for an axle of claim 1, wherein the outer sidewall of the spacer is in clearance fit with the inner sidewall of the inner support ring and the inner sidewall of the outer support ring.

3. The maintenance-free rim assembly for an axle of claim 2, wherein an end of the spacer facing the inner bearing is provided with a guide chamfer located on an inner wall of the spacer.

4. The maintenance-free rim assembly for an axle according to claim 1, wherein an outer support ring mounting surface, an inner support ring mounting surface, an outer bearing mounting surface, and an inner bearing mounting surface are provided on an inner wall of the mounting through hole in an axial direction of the mounting through hole, the outer support ring, the inner support ring, the outer bearing, and the inner bearing being respectively in corresponding abutment with the outer support ring mounting surface, the inner support ring mounting surface, the outer bearing mounting surface, and the inner bearing mounting surface;

a containing cavity is formed between the inner wall of the mounting through hole and the outer side wall of the spacer bush;

the number of the spacers is at least one, a deformation ring is arranged in the middle of one spacer, and the deformation ring protrudes towards the accommodating cavity.

5. The maintenance-free rim assembly for an axle of claim 1, wherein the bearing unit further comprises a sealing ring, a thrust washer and an outer clamping spring, which are sequentially arranged, the sealing ring is located on the outer side of the outer bearing, and the outer clamping spring is clamped with the mounting through hole.

6. The maintenance-free wheel rim assembly for an axle of claim 5, wherein the inner diameter of the sealing ring is in clearance fit or interference fit with the outer diameter of the inner ring of the outer bearing;

and clearance fit is formed between the thrust washer and the radial direction of the sealing ring and between the thrust washer and the axial direction of the outer clamp spring so as to form labyrinth seal on the outer bearing.

7. The maintenance-free wheel rim assembly for an axle of claim 6, wherein a first oil reservoir is formed between the outer support ring and the seal ring.

8. The maintenance-free wheel rim assembly for an axle according to any one of claims 1 to 7, wherein the bearing unit further comprises an inner retainer ring, an inner retainer spring and an oil seal which are sequentially arranged, the inner retainer ring is located on the inner side of the inner bearing, and the inner retainer spring is clamped with the mounting through hole.

9. The maintenance-free rim assembly for an axle of claim 8, wherein the inner retainer ring is provided with a support section that abuts against an outer diameter of an inner ring of the inner bearing;

the external diameter of the inner support ring is in clearance fit with the inner side wall of the mounting through hole and the inner clamping spring.

10. The maintenance-free wheel rim assembly for an axle of claim 9, wherein a second oil reservoir is formed between the inner support ring and the inner retainer ring.