A drum rear axle assembly for a new energy passenger vehicle

Abstract

The present invention discloses a drum rear axle assembly for a new energy bus, which includes a rear axle housing, a main reducer with a differential assembly, a brake drum, a drum brake assembly, a brake camshaft, a brake clearance adjusting arm, a brake chamber, a wheel hub bearing unit and a half shaft; by designing the wheel hub bearing unit as a pre-assembled part, after tightening the inner ring of the bearing according to the set torque value during the assembly of the rear axle assembly, the bearing clearance can be ensured to be at the optimal value, and within this optimal clearance, the bearing can be ensured to be within the design life; moreover, by filling extreme pressure high-temperature resistant grease in the bearing space at one time during pre-assembly, there is no need to replace the lubricating oil or grease during the use process; thus, it is realized that the bearings do not need to be maintained and replaced during the service life of the whole vehicle, the wheel side structure is maintenance-free, the maintenance cost is saved, and the attendance rate of the whole vehicle is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy buses, and particularly to a drum rear axle assembly for new energy buses. Background Art

[0002] With the progress of new energy drive technology, the trend of large-scale models for medium and short-distance passenger transportation has become the development trend of passenger transportation. In order to meet the increasing requirements of passengers for the riding experience, passenger transport enterprises are gradually improving the control of the overall vehicle comfort and the overall vehicle running noise. In addition, with the continuous research and development and application of new technologies and new processes, the main engine factory has put forward higher requirements for the quality of the rear axle assembly parts, hoping that the parts that need to be regularly maintained and serviced in the original structure can be exempted from maintenance or the maintenance interval can be extended.

[0003] The wheel side structure of the existing drum rear axle assembly for new energy buses is generally as follows: inner bearings and outer bearings are arranged inside the hub, and the bearing clearance is adjusted manually during the installation of the rear axle assembly. It is difficult to ensure the consistency of manual adjustment, and the service life of the bearings is not as expected. Only a regular maintenance cycle with a quality assurance period is set, and customers are required to regularly disassemble, maintain, replace the grease or bearings according to the maintenance cycle.

[0004] The brake friction pads on the drum brakes of the existing drum rear axle assembly for new energy buses are consumable parts, and must be replaced when worn to the limit. Since the brake is installed inside the hub bearing unit, the brake shoe is fixed to the brake back plate through the brake shoe pin. When replacing the friction pads, the brake shoe needs to be disassembled from the brake back plate. At this time, the hub bearing unit needs to be disassembled first. In this way, when the hub bearing unit is reassembled for the second time, due to the limitations of conditions such as the maintenance site, personnel, and equipment, it is very difficult to ensure the tightening torque of the hub bearing locking nut and the cleanliness inside the parts during the disassembly and assembly process, resulting in the hub bearing unit not reaching the designed service life.

[0005] In summary, the existing drum rear axle assembly for new energy buses needs to regularly maintain the wheel side, replace the grease, and the inner and outer bearings of the hub, etc. The maintenance frequency is high, the maintenance cost is large, and the overall vehicle attendance rate is low. Summary of the Invention

[0006] The purpose of the present invention is to provide a drum rear axle assembly for new energy buses, which has a simple structure, low running noise, and the hub bearings are exempt from maintenance, and can meet the continuous development needs of new energy buses.

[0007] The first technical solution adopted by the present invention is: a drum rear axle assembly for a new energy bus, comprising a rear axle housing, a main reducer with differential assembly, a brake drum, a drum brake assembly, a brake camshaft, a brake clearance adjusting arm, a brake chamber, a wheel hub bearing unit and a half shaft; the main reducer with differential assembly is arranged in the middle of the rear axle housing, the drum brake assembly and the wheel hub bearing unit are arranged at both ends of the rear axle housing, the brake drum is sleeved outside the drum brake assembly and the wheel hub bearing unit and fixed on the wheel hub bearing unit by bolts, the brake chamber is arranged at both ends of the rear axle housing through a brake chamber bracket; one end of the brake clearance adjusting arm is connected to the brake chamber, and the other end is connected to the brake camshaft; the other end of the brake camshaft is connected to the brake shoe of the drum brake assembly; the half shaft passes through the cavity of the rear axle housing, its front end is connected to the half shaft gear of the main reducer with differential assembly, and the rear end is fixed on the wheel hub bearing unit by bolts; the wheel hub bearing unit includes a wheel hub and an inner bearing, an inner oil seal, an outer bearing and an outer oil seal installed in the inner cavity of the wheel hub, the inner and outer bearings are respectively press-fitted into the inner cavity of the wheel hub by interference fit of their bearing outer rings, the end faces of the bearing inner rings of the inner and outer bearings are abutted against each other, the other end face of the bearing inner ring of the inner bearing abuts against the step surface of the rear axle housing, and the other end face of the bearing inner ring of the outer bearing is fastened to the rear axle housing by a lock nut; the inner oil seal is press-fitted into the inner cavity of the wheel hub by interference fit, and the inner ring of the oil seal is hermetically sleeved on the bearing inner ring of the inner bearing; the outer oil seal is press-fitted into the inner cavity of the wheel hub by interference fit, and the inner ring of the oil seal is hermetically sleeved on the bearing inner ring of the outer bearing; the space sealed by the inner and outer oil seals is filled with extreme pressure high temperature resistant grease.

[0008] Adopting the above technical solution, the wheel hub bearing unit is designed as a pre-assembled part. When pre-assembling, the bearing outer ring is pre-fixed by interference fit. After the inner ring of the bearing is tightened according to the set torque value during the assembly of the rear axle assembly, the clearance between the inner bearing and the outer bearing can be ensured to be at the optimal value. Within this optimal clearance, the bearing can be ensured to be within the designed service life; and, when pre-assembling, extreme pressure high temperature resistant grease is filled into the bearing space at one time, and there is no need to replace the lubricating oil or grease during the use process; thus, it is realized that the bearings do not need to be maintained and replaced during the service life of the whole vehicle, the wheel side structure is maintenance-free, the maintenance cost is saved, and the attendance rate of the whole vehicle is increased.

[0009] The second technical solution adopted by the present invention is an improvement on the first technical solution. The second technical solution adopted by the present invention is: the bearing inner rings of the inner and outer bearings are connected by a snap ring arranged on the inner side surface of the bearing inner ring, and an intermediate sealing ring is arranged on the outer side surface at the connection of the two bearing inner rings.

[0010] Adopting the above technical solution, on the one hand, after the inner and outer bearings are installed on the wheel hub, the bearing inner ring will not fall off during the transportation process; on the other hand, the design of the intermediate sealing ring can further prevent the leakage of the grease in the bearing space and ensure the service life of the bearing.

[0011] The third technical solution adopted by the present invention is an improvement on the second technical solution. The third technical solution adopted by the present invention is: the drum brake assembly includes a brake base plate, a locking bolt, a brake shoe, a brake shoe pin and a dust cover; the brake base plate is fixed to the rear axle housing by bolts, the brake shoe is rotatably mounted on the brake base plate by the brake shoe pin, the locking bolt passes through the brake base plate and is screwed into the brake shoe pin to limit the rotation of the brake shoe pin; the dust cover is fixed to the rear side of the brake base plate by screws, and a first brake shoe pin disassembly hole corresponding to the brake shoe pin is provided on the dust cover, and the aperture of the first brake shoe pin disassembly hole is larger than the outer diameter of the brake shoe pin; a second brake shoe pin disassembly hole is cast on the outer flange surface of the wheel hub, the second brake shoe pin disassembly hole and the brake shoe pin on the brake are on the same distribution circle, and the aperture of the second brake shoe pin disassembly hole is larger than the outer diameter of the brake shoe pin.

[0012] With this technical solution, when replacing the brake shoe friction lining, the brake shoe pin and brake shoe can be removed and installed through the brake shoe pin removal hole on the wheel hub, without having to remove the wheel hub bearing unit. This keeps the wheel hub bearing unit in its original installation state, achieving a maintenance-free wheel rim structure.

[0013] The fourth technical solution adopted by the present invention is an improvement on the third technical solution. The fourth technical solution adopted by the present invention is that two brake shoe pin disassembly holes are provided and are symmetrically distributed at 180°.

[0014] The above technical solution is adopted to make the two brake shoe pin disassembly and assembly holes on the same distribution circle and arranged 180° symmetrically, in order to ensure the balance of the wheel hub during operation and rotation, and avoid tire shaking and accelerated wear caused by excessive dynamic imbalance of the wheel hub.

[0015] The fifth technical solution adopted by the present invention is an improvement on the first technical solution. The fifth technical solution adopted by the present invention is that a half-shaft oil seal is provided between the rear axle housing and the half-shaft.

[0016] The above technical solution can ensure that the lubrication system inside the hub bearing unit and the lubricating oil of the final reducer with differential assembly do not communicate with each other, further improving the service life of the bearings of the hub bearing unit.

[0017] The sixth technical solution adopted by the present invention is an improvement on the first technical solution. The sixth technical solution adopted by the present invention is: the final reducer with differential assembly includes a final reducer housing, a driving gear, a driven gear and a differential; the differential includes a differential housing, a half-shaft gear and a planetary gear and a planetary gear shaft; the final reducer housing is fixed to the rear axle housing by bolts, the driving gear is connected to the drive motor by a flange flange installed at the end of its gear shaft, the driven gear is meshed with the driving gear, the differential housing is rotatably provided on the final reducer housing by a bearing and is fixed to the driven gear by bolts, the planetary gears are fixed in the differential housing by the planetary gear shaft, the planetary gears are meshed with the half-shaft gears, and the half-shaft gears are connected to the half-shafts by splines.

[0018] The adoption of the above technical solution can make the rear axle assembly structure simple, the operating noise low, and the wheel hub bearing maintenance-free, which can meet the sustainable development needs of new energy buses.

[0019] The beneficial effects of the present invention are as follows: the drum-type rear axle assembly of the present invention, by designing the wheel hub bearing unit as a pre-assembled part, pre-fixing the outer ring of the bearing by interference fit during pre-assembly, and tightening the inner ring of the bearing according to the set torque value during assembly of the rear axle assembly, can ensure that the clearance between the inner bearing and the outer bearing is at an optimal value, and the wheel hub bearing can be guaranteed to be within the design life within this optimal clearance; by filling the bearing space with extreme pressure and high temperature resistant grease at one time during pre-assembly, there is no need to replace the lubricating oil or grease during use, thereby achieving the goal of not having to maintain or replace the bearings during the use cycle of the entire vehicle, achieving maintenance-free wheel side structure, saving maintenance costs, and increasing the attendance rate of the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a schematic diagram showing the appearance and structure of a drum rear axle assembly for a new energy bus according to embodiment 1 of the present invention.

[0021] Figure 2 It is a schematic diagram of the wheel side structure of Example 1.

[0022] Figure 3 It is a schematic diagram of the connection between the final reducer with differential assembly and the rear axle housing of Example 1.

[0023] Figure 4 It is a schematic structural diagram of the hub bearing unit of Example 1.

[0024] Figure 5 yes Figure 4 side view.

[0025] Figure 6 Schematic diagram of the brake assembly of Example 1.

[0026] Figure 7 yes Figure 6 side view. Detailed Embodiments

[0027] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments. However, the content of the present invention is not limited to the following embodiments only.

[0028] Embodiment 1

[0029] Refer to Figure 1 , this embodiment provides a drum rear axle assembly for a new energy bus, including a rear axle housing 1, a main reducer with differential assembly 3, a brake drum 4, a drum brake assembly 14, a brake camshaft 5, a brake chamber bracket 7, a brake clearance adjusting arm 8, a brake chamber 9, wheel bolts 10, a hub bearing unit 11, and a half shaft 13.

[0030] The rear axle housing 1 is composed of a middle section of the axle housing, an axle housing cover, and a half shaft sleeve. The middle section of the axle housing is spindle-shaped with smaller ends and a larger middle part. A cavity for accommodating the main reducer with differential assembly 3 is provided in the middle part. The axle housing cover is welded to the bottom of the cavity, and a flange is welded to the top of the cavity for installing the main reducer housing. The half shaft sleeves are welded to both ends of the middle section of the axle housing for installing components such as half shafts, hub bearing units, drum brake assemblies, and brake chamber brackets.

[0031] Refer to Figure 3 , the main reducer with differential assembly 3 includes a main reducer housing 31 and an active gear 33, a passive gear 34, and a differential arranged in the main reducer housing 31; the differential includes a differential housing 35 and a half shaft gear 36, a planetary gear 37, and a planetary gear shaft 38 arranged in the differential housing 35. The main reducer housing 31 is fixed to the rear axle housing 1 by bolts 2. The active gear 33 is connected to the drive motor through a flange flange 32 installed at the end of its gear shaft. The passive gear 34 meshes with the active gear 33 to form a gear pair. The differential housing 35 is rotatably arranged in the main reducer housing 31 through bearings and is fixed to the back of the passive gear 34 by bolts to rotate synchronously with the passive gear 34. The planetary gear 37 is fixed in the differential housing 35 through the planetary gear shaft 38 and rotates synchronously with the differential housing 35; the half shaft gear 36 is meshed and connected with the planetary gear 37.

[0032] Refer to Figure 4 and Figure 5, the hub bearing unit 11 includes a hub 111, an inner oil seal 116, an inner bearing 115, an outer bearing 112, an outer oil seal 113, a snap ring 114 and an intermediate sealing ring 117. The hub 111 is provided with an inner cavity for installing the hub bearing. An annular blocking portion is provided at the axial center of the inner cavity of the hub. Two shoulder portions are formed on both sides of the annular blocking portion. The outer bearing 112 is press-fitted into the inner cavity of the hub. The outer ring 1122 of the outer bearing is connected to the hub by interference fit. The inner end face of the outer ring 1122 abuts against one shoulder of the hub. The inner bearing 115 is press-fitted into the inner cavity of the hub. The outer ring 1152 of the outer bearing is connected to the hub by interference fit. The inner end face of the outer ring 1152 abuts against the other shoulder of the hub. The end faces of the inner ring 1121 of the outer bearing and the inner ring 1151 of the inner bearing are in contact with each other. The inner sides of the two inner rings are connected by a snap ring 114. An intermediate sealing ring 117 is provided on the outer side of the connection portion of the two inner rings. The inner oil seal 116 is press-fitted into the inner cavity of the hub by interference fit of its outer oil seal ring. Its inner oil seal ring is a lip seal surface and is fitted on the inner ring 1151 of the inner bearing; the outer oil seal 113 is press-fitted into the inner cavity of the hub by interference fit of its outer oil seal ring. Its inner oil seal ring is a lip seal surface and is fitted on the inner ring 1121 of the outer bearing; a relatively closed bearing space is formed among the inner oil seal 116, the outer oil seal 113 and the intermediate sealing ring 117. Extreme pressure high-temperature resistant grease is filled in this space.

[0033] Two brake shoe pin disassembly and assembly holes 1111 are cast on the outer flange surface of the hub 111. The two brake shoe pin disassembly and assembly holes 1111 and the brake shoe pins on the brake are on the same distribution circle and are symmetrically distributed at 180°. The aperture of the brake shoe pin disassembly and assembly hole is larger than the outer diameter of the brake shoe pin.

[0034] Refer to Figure 2 , the hub bearing unit 11 is sleeved on the rear axle housing 1 through its inner bearing 115 and outer bearing 112. The other end face of the inner ring 1151 of the inner bearing abuts against the step surface of the rear axle housing. The other end face of the inner ring 1121 of the outer bearing is fastened to the rear axle housing 1 by a lock nut 18; the wheel bolts 10 are press-fitted into the hub 111 by interference fit. The two half shafts 13 respectively pass through the half shaft sleeves of the rear axle housing 1 axially. The outer splines at their front ends are connected to the inner splines on the half shaft gears 36. The flange ends are fixed to the hub 111 of the hub bearing unit 11 by half shaft mounting bolts 12. An axle oil seal 17 is provided between the half shaft 13 and the rear axle housing 1. The driving motor distributes power to the left and right half shafts 13 through the main reducer with differential assembly 3. The half shaft 13 drives the hub to rotate and drives the whole vehicle to travel.

[0035] Refer to Figure 6 and Figure 7, the drum brake assembly 14 includes a brake backing plate 141, a set bolt 145, brake shoes 142, brake shoe pins 144 and a dust cover 146. The brake backing plate 141 is fixed to the rear axle housing 1 by bolts 15. The brake shoes 142 are rotatably mounted on the brake backing plate 141 through the brake shoe pins 144, and brake shoe friction linings 143 are provided on the brake shoes 142. The set bolt 145 passes through the brake backing plate 141 and is screwed into the brake shoe pin 144. The fixing or loosening of the brake shoe pin 144 can be achieved by tightening or loosening the set screw 145. The dust cover 146 is fixed to the rear side of the brake backing plate 141 by screws, and first brake shoe pin disassembly and assembly holes corresponding to the brake shoe pins 144 one by one are provided on the dust cover 146.

[0036] The drum brake assembly 14 is fixed to the rear axle housing 1 inside the hub bearing unit 11 by brake installation bolts 15. A first camshaft hole is provided on the brake backing plate 141 in the drum brake assembly 14; the brake drum 4 is sleeved on the hub bearing unit 11 and the drum brake assembly 14 and is fixed to the hub 111 of the hub bearing unit 11 by installation bolts 16. The brake chamber bracket 7 is fixed to the rear axle housing 1 by installation bolts 6. The brake chamber 9 is installed and fixed on the chamber bracket 7 through its own installation bolts and nuts. At the same time, it is connected to the brake clearance adjusting arm 8 through its own push fork. A second camshaft hole is provided on the brake chamber bracket 7. One end of the brake camshaft 5 passes through the first camshaft hole on the brake backing plate 141 and is connected to the brake shoe 142, and the other end passes through the second camshaft hole on the brake chamber bracket 7 and is connected to the internal spline on the brake clearance adjusting arm 8 through the external spline at its head end. During braking, the brake clearance adjusting arm 8 drives the brake camshaft 5 to rotate under the air pressure of the brake chamber 9, and pushes the brake shoe to press against the brake drum 4 to achieve braking.

[0037] When replacing the brake shoe friction lining 143, there is no need to disassemble the hub bearing unit 11. Rotate the hub bearing unit 11 to align the brake shoe pin disassembly and assembly hole 1111 on the hub 111 with the brake shoe pin 144, loosen the set screw 145, and tap the brake shoe pin 145 from any one side of the dust cover 146 or the hub bearing unit 11 to the other side, then the disassembly can be completed. During installation, tap the brake shoe pin 144 from any one side of the wheel dust cover 146 or the hub bearing unit 11 to the other side to the correct position, and tighten the set screw 145 to complete the installation. The whole process does not require disassembling the hub bearing unit, so that the hub bearing unit is always in the initial installation state, thus realizing the maintenance-free function of the wheel side structure.

[0038] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A drum rear axle assembly for a new energy bus, comprising a rear axle housing, a main reducer with differential assembly, a brake drum, a drum brake assembly, a brake camshaft, a brake clearance adjusting arm, a brake chamber, a wheel hub bearing unit and a half shaft; the main reducer with differential assembly is arranged in the middle of the rear axle housing, the drum brake assembly and the wheel hub bearing unit are arranged at both ends of the rear axle housing, the brake drum is sleeved outside the drum brake assembly and the wheel hub bearing unit and fixed on the wheel hub bearing unit by bolts, the brake chamber is arranged at both ends of the rear axle housing through a brake chamber bracket; one end of the brake clearance adjusting arm is connected with the brake chamber, and the other end is connected with the brake camshaft; the other end of the brake camshaft is connected with the brake shoe of the drum brake assembly; the half shaft passes through the cavity of the rear axle housing, its front end is connected with the half shaft gear of the main reducer with differential assembly, and the rear end is fixed on the wheel hub bearing unit by bolts; its characterized in that: The wheel hub bearing unit includes a wheel hub and an inner bearing, an inner oil seal, an outer bearing and an outer oil seal installed in the inner cavity of the wheel hub. The inner and outer bearings are respectively press-fitted into the inner cavity of the wheel hub by interference fit of their bearing outer rings. The end faces of the bearing inner rings of the inner and outer bearings are in contact with each other. The other end face of the bearing inner ring of the inner bearing abuts against the step surface of the rear axle housing, and the other end face of the bearing inner ring of the outer bearing is fastened on the rear axle housing by a lock nut; the inner oil seal is press-fitted into the inner cavity of the wheel hub by interference fit, and the inner ring of the oil seal is hermetically sleeved on the bearing inner ring of the inner bearing; the outer oil seal is press-fitted into the inner cavity of the wheel hub by interference fit, and the inner ring of the oil seal is hermetically sleeved on the bearing inner ring of the outer bearing; the space sealed by the inner and outer oil seals is filled with extreme pressure high temperature grease; The bearing inner rings of the inner and outer bearings are connected by a snap ring arranged on the inner side surface of the bearing inner ring, and an intermediate sealing ring is arranged on the outer side surface at the connection of the two bearing inner rings; A half shaft oil seal is arranged between the rear axle housing and the half shaft.

2. The drum rear axle assembly for new energy buses according to claim 1, characterized in that: The drum brake assembly includes a brake backing plate, a set screw, brake shoes, brake shoe pins and a dust cover; the brake backing plate is fixed on the rear axle housing by bolts, the brake shoes are rotatably installed on the brake backing plate through the brake shoe pins, the set screw passes through the brake backing plate and is screwed into the brake shoe pin to limit the rotation of the brake shoe pin; the dust cover is fixed on the rear side of the brake backing plate by screws, and the dust cover is provided with first brake shoe pin disassembly and assembly holes corresponding to the brake shoe pins one by one. The aperture of the first brake shoe pin disassembly and assembly hole is larger than the outer diameter of the brake shoe pin; A second brake shoe pin disassembly and assembly hole is cast on the outer flange surface of the wheel hub. The second brake shoe pin disassembly and assembly hole and the brake shoe pin on the brake are on the same distribution circle, and the aperture of the second brake shoe pin disassembly and assembly hole is larger than the outer diameter of the brake shoe pin.

3. The drum rear axle assembly for new energy buses according to claim 2, characterized in that: There are two brake shoe pin disassembly and assembly holes, and they are symmetrically distributed at 180°.

4. The drum rear axle assembly for new energy buses according to claim 1, wherein: The main reducer with differential assembly includes a main reducer housing, a driving gear, a driven gear and a differential; the differential includes a differential housing, half axle gears, planetary gears and planetary gear shafts; the main reducer housing is fixed to the rear axle housing by bolts, the driving gear is connected to the drive motor through a flange flange installed at the end of its gear shaft, the driven gear is meshed and connected with the driving gear, the differential housing is rotatably arranged in the main reducer housing through bearings and is fixed to the driven gear by bolts, the planetary gears are fixed in the differential housing through planetary gear shafts, the planetary gears are meshed and connected with the half axle gears, and the half axle gears are connected to the half axles through splines.

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