Automotive Steering Rack Damage Analysis

With the continuous development of the times and the progress of science and technology, the car steering racks are also being updated, from the initial mechanical steering gears to power steering racks, and the power steering gears are evolving to incorporate more technological elements to make the car steering more and more light and intelligent. But at the same time, car steering is becoming more and more complex, and also gives rise to a variety of unprecedented damage problems.

This article popularizes the basic structure and classification of steering gear and analyzes the causes of steering gear damage through macroscopic examination and body microscopic examination. Analyze the causes of steering rack damage. It provides direction for the investigation of steering gear damage in forensic appraisal and insurance public valuation work.

1 Introduction to the steering rack

The steering system is very important for the safety of the car, and the steering gear, as the actuator for steering, is the most important. According to the source of steering power, automotive steering gears can be divided into mechanical and power steering gears, among which the development of power steering gears has led to hydraulic and electro-hydraulic power and electric power steering gears.

1) Mechanical steering rack

The mechanical steering power source is entirely the driver’s hand force, and its performance is stable and simple, but the steering wheel rotation is relatively laborious.

2) Power steering system

The power steering system is a device that relies on the power generated by the engine to assist the driver in steering. It converts the kinetic energy generated by the engine into hydraulic pressure, pneumatic pressure, or electric energy, and then converts the hydraulic pressure, pneumatic pressure, or electric energy into mechanical energy that can assist the driver to control the steering system, so it is called power-assisted steering system.

a. Hydraulic power steering system

The hydraulic power steering system is usually composed of mechanical steering The hydraulic power steering system is usually composed mechanical steering apparatus, oil pump, booster cylinder, fluid reservoir, oil pipe, and steering The hydraulic power steering system is usually composed of mechanical steering gear, oil pump, booster cylinder, fluid reservoir, oil pipe and steering control valve assembly, etc. The hydraulic power steering system is usually composed of mechanical steering gear, oil pump, booster cylinder, fluid reservoir, oil pipe, and steering control valve assembly.

Among them, the steering control valve controls the amount of oil pressure flowing to the booster cylinder through the amount of torque and direction of rotation of the steering wheel of the car and controls the amount of steering power. Even though the hydraulic steering system is gradually abandoned by major automobile manufacturers, the hydraulic steering inherits the characteristics of simple structure and reliable performance of the mechanical steering.

2) Electro-hydraulic power steering system

With the deterioration of the environment and the increasing attention to automobile safety, the problems and disadvantages of the hydraulic power steering system are gradually magnified, and people begin to optimize and improve it, and a new type of electro-hydraulic power steering system is born. The new electro-hydraulic power steering system was born, and its improvement point is to integrate the speed signal into the hydraulic steering system and adjust the electro-hydraulic power steering device according to the different speeds of the car, which makes the steering lighter when the car is driving at low speed and makes the steering more stable when the car is driving at high speed.

3) Electric power steering

The electric power steering system has improved the disadvantages of the hydraulic power steering system from the root. The common electric power steering system for cars, consists of the steering wheel, speed sensor, torque sensor, booster motor, controller and its reduction mechanism, etc. The hydraulic system components are all eliminated.

The operation principle is that the driver turns the steering wheel to the direction and size of the torque on the steering wheel transmitted to the torque sensor, and then through the controller to adjust the power control, change the power motor to provide the power torque size, and combined with the different speed to control the road sense, to ensure the safety and reliability of driving.

2 Problems with the electric power steering system

The electric power steering system, especially the steering gear, also has many problems in normal use.

1) Abnormal steering torque

Case: A brand of the vehicle with electric power steering was found to have insufficient steering torque in use and could not return to positive automatically.

After inspection, the vehicle’s steering grease was emulsified, and the rust on both sides of the steering rack was serious, i.e. the water in the steering housing corroded the steering return control circuit and caused abnormal return control.

The water inside the steering gear housing

2）Strange sound and stalling when steering

Case 1: A brand of the vehicle with electric power steering installed was found to have strange noise when steering, and the system had no fault code.

After inspection, the ball surface inside the electric power steering screw was corroded and the ball surface contact made a strange noise when the steering was in operation.

Corrosion of screwball

Case 2: A brand of the vehicle with electric power steering was found to have a strange noise when steering, and the system had no fault code.

After inspection, the steering gear left dust sleeve broken, resulting in the vehicle in the wading road when the water through the dust sleeve broken parts into the steering machine inside, resulting in the steering gear left lubrication performance decline, wear intensified, triggering the steering gear left surface treatment layer damage, and gradually fall off, corrosion resistance is weakened, the damage gradually increased, causing the steering gear left the noise and stalling phenomenon.

Water rust in the steering rack

3) No power steering

Case: A brand vehicle with electric power steering was found to have no power steering in use, and the system showed that the steering gear needed to be replaced.

After inspection, the three-phase power supply line of the electric power steering motor was fused, and the vehicle was used for a long time when the steering wheel did not return to the right, and the power supply to the power steering motor continued for a long time when the engine was running continuously and there was steering force, which made it overload and fuse.

Power cord fused

3 Conclusion

With the continuous progress of social technology, the automobile industry is also developing rapidly, but its development has also brought many problems. This paper mainly describes the current automobile usually uses The common problems of the electric power steering system, through macroscopic examination and microscopic magnification of the body microscope to analyze the causes of damage in the actual use of electric power steering system, can help people quickly find the root cause of damage and develop a solution.