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UNIM Technology Knowledge: Present Situation and Development Direction of Automobile Bearing

Engine bearing, hydraulic pump bearing, platform separator bearing, gearbox bearing, hub bearing and constant velocity universal joint

 

At present, the international automobile industry is developing automobile rolling bearings in the aspects of safety, comfort, ease of use and high reliability. With the progress of automobile technology, considerable progress has been made in improving the performance, quality and diversification of bearing forms. Automobile bearings are usually classified according to the parts used. They mainly include: engine bearing, hydraulic pump bearing, platform separator bearing, gearbox bearing, hub bearing and constant velocity universal joint.

 

1. Engine bearing

Sealed ball bearings are commonly used in engine bearings. With the increase of engine speed, the working temperature is higher and higher. In order to meet this requirement, the bearing is developing in the direction of low noise and better sealing performance, and new sealing materials and lubricating materials have been developed. Even the sleeve is made of ceramics. The sealed cage is made of fluororubber with high temperature resistance up to 200 C. High temperature resistant grease is used, ceramic bearing is used, and ceramic material is used for sleeve and rolling element. The ceramic composition is siz. This kind of material has good wear resistance, and still has good running performance under the condition of limited slip conditions.

 

2.hydraulic pump bearing

The water pump bearing works in the environment of water droplet splashing. It is not conducive to improving the service life of most of the single row and light-duty water pump bearings in China. SKF and RHP developed water pump shaft. The bearing has a variety of structures: double row ball type and one row ball and one row needle roller (or roller) type. In this structure, the inner cage is integrated with the water pump shaft, which reduces the distance between the two rows of rolling elements and makes it possible to miniaturize the water pump bearing. In the ball ball type, it can be designed as a "double row angular contact" structure, and in the ball roller structure, the ball bearing can be designed as a "three-point contact" or "three-point contact". Four point contact "structures, which can improve the axial bearing capacity and have small axial clearance.


hydraulic pump bearing 

 

3. Clutch bearing

The working conditions of the off platform bearing are high speed, high temperature, strong vibration, displacement between the engine and the transmission, eccentricity between the sliding sleeve and the gearbox, etc., which requires the absolute reliability of the clutch bearing. The common structures of automobile dispenser bearings in China are: thrust ball bearing, centripetal ball bearing and angular contact ball bearing. The bearings do not have centering performance. When used for diaphragm spring, the eccentric wear of the dispenser claw is often caused by the non concentricity between the bearing and the dispenser disk. SKF company developed a completely new generation of platform lifter bearings in the mid-1970s. The ferrule is formed by stamping with steel plate and nylon cage. Compared with ordinary off platform bearing, it can reduce the weight by 50%, simplify the process and low cost. It can effectively prevent the leakage of lubricating grease, realize radial adjustment, reduce adverse additional stress, effectively reduce the bearing noise and greatly improve the service life.

 

4. Transmission bearing

The common types of bearing structures in gearbox include needle roller bearing (centripetal roller and cage assembly, stamped outer ring needle roller bearing), ball bearing (sealed ball bearing, four point contact ball bearing, etc.), cylindrical roller bearing, tapered roller bearing and ball roller combined bearing.

 

4.1 Ball bearing

In order to improve the service life of ball bearing, it is often used to increase the diameter and quantity of steel balls. The methods are as follows: ① adopt the structure with ball loading notch; ② Shallow pocket cage is adopted; ③ Four point contact is adopted. The actual effect of the above method is not obvious. Through experimental analysis, it is mainly because the foreign matter (dust) in the lubricating oil enters the bearing, which greatly shortens the service life of the bearing. As foreign matters invade the rolling contact surface of the bearing, indentation is generated, resulting in crack or surface peeling, resulting in shortened service life. The following methods can be adopted: improving the sealing structure to prevent foreign matters from invading, which can effectively reduce the noise and improve the service life and reliability. Compared with sealed ball bearings, the service life of open bearings with the same structure and size is 6 ~ 10 times different.

 

4.2 Tapered roller bearing

With the development of light and miniaturization of gearbox, tapered roller bearings that can bear radial and axial composite forces are mostly used. Compared with ball bearing, in structure, the roller end face and inner ring large retaining edge of tapered roller bearing often slide under contact load, which is larger than the friction torque of ball bearing. In order to improve these shortcomings, a retaining structure which can realize low friction moment is developed, and the friction moment is only the original.

 

Tapered roller bearing 

 

3. Cylindrical roller bearing

Transmission ball bearing is developing towards cylindrical roller bearing. In order to improve the axial bearing capacity of cylindrical roller bearing, SKF company changed the inner side of the retaining edge to conical, improved the contact and lubrication conditions between the roller end face and the retaining edge, reduced the sliding friction between the roller and the retaining edge, and improved the service life of the bearing. Recently, the SU type structure has been developed. The inner side of the retaining edge is conical, and the end face of the roller is designed into a spherical shape. The axial bearing capacity is greatly strengthened, and the value of the bearing is improved.


Cylindrical roller bearing 

 

4. Needle roller bearing

The needle roller holder assembly on the gearbox gear shaft usually adopts turning cage and stamping cage, but micro vibration wear can not be avoided. In order to improve the bearing capacity, the length and number of needle rollers are increased, but the manufacturing difficulty of cage is increased. With the development of polymer materials, engineering plastic cage has the advantages of convenient manufacture and low cost, which provides a solution to the problem. In addition, unequal spacing cages with pockets and split cages are also developed.

 

Needle roller bearing 

 

The support bearing of small-sized gearbox often adopts stamped outer ring needle roller bearing. The advantages of this bearing are:(1) small outer diameter size, which is conducive to the miniaturization of gearbox. (2)simple axial fixation of shell and bearing. (3)low cost and simple manufacture.

 

5. Hub bearing

Most domestic cars use two sets of single row tapered roller bearings. In recent years, with the development of front drive car, the hub bearing is developing in the direction of unitization. Its main advantages are no need to adjust the bearing assembly clearance, light and miniaturization, high reliability and low cost.

 

 

The current practical hub bearing unit can be divided into generation 1, generation 2, generation 3 and generation 4 according to its structural changes. There are two structural types: double row angular contact ball bearing unit and double row tapered roller bearing unit.

 

Generation 1: outer ring integral double row bearing, filled with grease, ordinary bearing with seal. This kind of bearing has been widely used in Europe. They are mainly double row angular contact ball bearings and double row tapered roller bearings.

 

Generation 2: outer ring with flange structure is easy to connect with matched parts (hub or knuckle).

 

Generation 3: the parts matched with the bearing and the bearing ring are made into a whole, the outer ring becomes a cutting structure, and the inner ring adds a flange, which reduces the vehicle parts, reduces the weight of the whole vehicle and improves the assembly conditions.

 

Generation 4: Based on the 3rd generation automobile hub bearing, it is integrated with the constant velocity universal joint of front drive, which further simplifies the automobile structure and is generally used for steering drive wheels.

 

6.Constant velocity universal joint

Constant velocity universal joint is an automobile part gradually produced by the bearing industry in recent years. It is widely used in front drive and four-wheel drive vehicles. Its main structures include BJ (ball cage type), DOJ(double effect compensation type), TJ (three pillar pin type) and VI (cross groove type), etc.

 

More about UNIM Wheel Hub Bearing:

The main function of hub bearing of UNIM is to bear load and provide accurate guidance for the rotation of hub. It bears both axial load and radial load. It is a very important part. The traditional automobile wheel bearing is composed of two sets of tapered roller bearings or ball bearings. The installation, oiling, sealing and clearance adjustment of the bearing are carried out on the automobile production line. This structure makes it difficult to assemble in the automobile factory, high cost and poor reliability. Moreover, when the automobile is maintained at the maintenance point, the bearing needs to be cleaned, oiled and adjusted. Hub bearing unit is developed on the basis of standard angular contact ball bearing and tapered roller bearing. It integrates the two sets of bearings. It has the advantages of good assembly performance, omitting clearance adjustment, light weight, compact structure, large load capacity, pre loading grease for sealed bearings, omitting external hub sealing and free from maintenance. It has been widely used in cars and gradually expanded in trucks.

 

Wheel Hub Bearing 

Wheel Hub Bearing


2022-05-23