Failure Analysis of Automobile Differential Planetary Gear

Introduction

This study aims to investigate the failure mechanism of automotive planetary gears, and
Propose corresponding optimization design to improve the life and stability of planetary gears.
qualitative, thereby improving the performance and safety of automobiles. In practical applications
In the process of planetary gear transmission, gear failure still occurs from time to time. Therefore, planetary gear failure It is necessary and important to conduct a research on the effectiveness analysis.
According to the research and experimental results, the failure of planetary gears mainly manifests as tooth surface fatigue.different modes of fatigue, such as tooth root fatigue and tooth surface peeling.
Labor is the most common form of failure, accounting for 55% ~60%.

At present, the research on contact fatigue of planetary gears has been widely
Researchers conducted experiments and numerical simulations to investigate the
The contact fatigue life and contact stress distribution of the wheel were deeply analyzed.
Research. At the same time, with the continuous improvement of material mechanical properties and the development of new The introduction of heat treatment methods has greatly improved the performance of planetary gears. Therefore, carrying out research on planetary gear contact fatigue is not only
It is helpful to improve the reliability and service life of gears, and can also provide valuable references for the research of other planetary gear transmission mechanisms. Experimental testing and analysis are the main research methods in this study.Through experimental testing, it was found that the failure of planetary gears mainly includes the tooth top Contact fatigue and tooth wear, of which the contact fatigue of the tooth tip is the main loss This proves that the design and manufacturing of planetary gears should Pay special attention to the contact problem of the tooth tip to ensure its life and use performance .

Structure and function of automotive differential

The differential is a mechanical device used in automotive transmission systems, The main function is to enable the engine-driven wheels to rotate freely, And overcome the resistance of the road surface when the vehicle is driving and the inner and outer wheels when turning different rotational speeds, ensuring safe and stable driving.The differential mechanism consists of a drive shaft, left and right wheel gears, sun gear, ring gear,The oil seal and oil lubrication system inside the differential. When the car is driving in a straight line When driving, the left and right wheel gears, sun gears, and ring gears of the differential will
It rotates together with the drive shaft; the left and right wheel gears rotate during driving
During the process, it is bound to be affected by different resistance or terrain, resulting in two
The wheel rotation speed is different; the oil lubrication system of the differential will Slide it between the left and right wheel gears and the sun gear, so that the left and right wheel gears The friction between the planetary gear and the sun gear is reduced, thus avoiding speed differences The impact on the vehicle. When the car turns, the differential can automatically adjust The speed of the whole left and right wheels is adjusted to adapt to the difference in driving distance between the inner and outer wheels That is to say, when the car turns, due to the outside wheel driving The distance between the inner and outer wheels is greater than that between the inner and outer wheels, which may cause slipping and dragging. The inner wheel may slip.

The failure manifestation and impact of planetary gear

The planetary gear is a very critical component in the automotive transmission system
If it fails, it will have a serious impact on the vehicle. Planetary gear The performance of wheel failure includes hearing a “quack” sound during driving, especially Second gear and third gear; the vehicle speed rises slowly and jumps during acceleration Blockage or inability to accelerate; vehicle jitter or vibration; increased fuel consumption;There is a significant sense of hesitation when changing gears; when manually shifting, the vehicle does not Switch to the designated gear. The effect of planetary gear failure is the brake Unable to operate normally, unable to drive the vehicle; the vehicle cannot go uphill and accelerate The speed is fast; the stability of the vehicle is reduced, and safety accidents are prone to occur; the planetary gear is lost This may cause damage to many other transmission and steering components, resulting in a decrease in overall vehicle performance.

Comprehensive analysis of failure causes of planetary gears

The causes of planetary gear failure mainly include the material properties of the gear itself.
Quality, process and quality issues may lead to gear failure over a long period of time.
Failure during use; proper use and maintenance of the planetary gear is very important
Yes, if not used and maintained in the correct way, the gear can The planetary gears may be damaged with the increase of the mileage of the car. The lubricating oil will become dirty and thick, resulting in the failure of the planetary gear; the planetary gear The longer the wheel is used, the wear and metal fatigue on the gear surface Factors will lead to gear failure; harsh conditions for the use of planetary gears
It may also be one of the reasons for gear failure, such as frequent use on steep roads.
The use of the vehicle, frequent rapid acceleration, sudden braking, frequent overloading, etc. can cause
The planetary gears fail prematurely. Therefore, the causes of planetary gear failure are Cracks on the outer bracket of the planetary gear, fatigue spalling on the tooth surface of the outer gear ring,
Tooth missing corner, welding of planet carrier, etc. In order to ensure the safety of planetary gear
The normal service life of the wheel should be regularly inspected and lubricating oil and oil seal should be replaced Do not use planetary gears under high stress conditions, and use appropriate
Properly reduce excessive driving operations under the conditions to reduce the wear of planetary gears
Risk of wheel failure.

Test detection and analysis

The experimental testing and analysis are important components of this study.This study investigated the failure mechanism of planetary gears through experimental testing. Multiple automotive planetary gears were tested and analyzed using a The macro and micro morphology of the fracture surface were analyzed, and the failure mechanism of the material was discussed. The physical and chemical testing and energy spectrum analysis of the microstructure found planetary gears The main cause of failure. Specifically, the study found that the failure of planetary gears The effect mainly includes two modes: tooth contact fatigue and tooth wear. Based on this, the failure mode and life of planetary gears can be predicted, which can provide guidance for optimizing the design of planetary gears. Chemical design provides important data support. In summary, experimental testing is One of the core contents of this study. Through these research methods, we can Deeply understand the failure mechanism and influencing factors of planetary gears, and propose More effective optimization design scheme.

Fracture location and macroscopic appearance

The test was conducted on multiple automotive planetary gears, and the failure
The fracture position and macroscopic morphology of the samples were observed and analyzed.
As shown in Figure 1, the observation results indicate that the fracture position of the planetary gear is mainly It should appear at the position of the tooth tip and root, and show typical fatigue fracture.
The fracture characteristics are characterized by smooth, curved fractures with typical
Groove pattern and multiple fatigue small cracks. This indicates tooth tip contact
Fatigue is the main failure mode of planetary gears.

Physical and chemical testing of failed parts

This study also conducted physical and chemical inspections on the failed parts of the planetary gears.
including the analysis of material composition, microstructure, and other aspects. The quality of the material itself is the key to the planet The main causes of gear failure are obvious defects and poor quality of materials.Uniformity can lead to excessive stress during high-load use, resulting in
and lead to failure. The focus is on the tooth top position of the material, which The maximum stress it can bear is easy to cause cracks and deformation. Test results The results show that the material composition of the failed parts of the planetary gear meets the requirements, and the hardness
Values correspond.

Microscopic morphology and energy spectrum analysis of the fracture

In order to gain a deeper understanding of the microscopic morphology of planetary gear failure,
The fracture surface of the planetary gear was also analyzed in this study. Microscopic morphology observation and energy spectrum analysis. The results showed that the fracture surface of the planetary gear had typical fatigue cracks and The groove phenomenon occurred, and a large number of microscopic fatigue cracks appeared. Energy spectrum analysis As shown in Figure 6 and Figure 7, the results show that the fracture surface element of the planetary gear is In the element distribution, the iron element increased significantly, which further proves that The main reason for the failure of planetary gears is the contact fatigue of the tooth tip.Get up.

Analysis, discussion and conclusion

The results of the test and analysis show that the main failure mechanism of the planetary gear is
It is caused by two modes: tooth top contact fatigue and tooth surface wear. The contact fatigue of the tooth tip is the main failure mode, which leads to the failure of the planetary gear. The main reason for the efficiency. In addition, working conditions such as torque and speed It is also important for the failure mode and failure life of planetary gears.Impact.

1) The tooth tip contact of the planetary gear should be considered in design and manufacturing
Issues that require special attention, on the premise of avoiding high stress concentration
The parameters such as tooth surface contact pressure and tooth root strength should be reasonably selected.To improve the life and stability of planetary gears.
2) The working conditions such as torque and speed should be based on actual needs
Reasonable selection can reduce the failure rate of planetary gears and extend their life.
3) Surface hardening technology and high-strength materials for planetary gears
Applying such improvement measures is to improve the life and stability of planetary gears
effective means. The test results show that the torque and speed of the planetary gears have a significant impact on failure Mode and failure life have important influences. Therefore, in the design and optimization of When optimizing planetary gears, reasonable selection should be made based on actual working conditions. parameters such as torque and speed. In addition, for the failure mode of planetary gears,In the form and mechanism, the use of high-strength materials and improved design can effectively improve the Long service life of high planetary gear.

Conclusion

This study provides a theoretical basis for the design and optimization of automotive transmission systems.important theoretical support and experimental data, which can improve the performance and
Security is of great significance. Future research can further deepen To explore the failure mechanism of planetary gears and propose more effective optimization Design scheme.

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