Braking jitter evaluation testing method for motor vehicle

Abstract

The invention discloses a braking jitter evaluation testing method for a motor vehicle, and the method comprises the steps: 1), increasing the speed of a vehicle to a first speed, and then decreasing the speed of the vehicle to a second speed in a state of engine jointing without a brake; 2), increasing the speed of the vehicle to a third speed from the second speed, and decreasing the speed of the vehicle to a fourth speed in the state of engine jointing through the brake, wherein the third speed is less than the first speed, and the fourth speed is less than the second speed; 3), increasing the speed of the vehicle to the third speed from the fourth speed, and then decreasing the speed of the vehicle to the fourth speed in the mode same as the mode at step 2), and repeatedly carrying out the braking process. The vehicle is provided with a plurality of sensors, and the sensors at least respectively record the speed, deceleration, temperature and acceleration signals of the vehicle at steps 1)-3), and carry out the processing of the signals.

Description

technical field [0001] The invention relates to a test method for evaluating brake judder of a motor vehicle. Background technique [0002] As an important safety component of a motor vehicle, the brake plays a very important role in the running and stopping of the motor vehicle. In recent years, due to people's higher and higher requirements for the comfort of passenger cars, the phenomenon of vehicle brake judder has gradually been paid attention to. Slight brake judder will be perceived by careful drivers, affecting comfort, and serious ones will Cause the vehicle to lose control and cause a safety accident. At present, foreign research on brake judder mainly focuses on the mechanism of generation and transmission path, and some achievements have been made, mainly including the establishment of stator-rotor and vehicle mathematical models to theoretically explain and analyze the phenomenon of brake judder. The analysis results show that the phenomenon of brake jitter is...

AI Technical Summary

Problems solved by technology

The analysis results show that the phenomenon of brake jitter is the combined effect of many factors. At present, the main factors include: first, the thickness difference and installation error in the design and manufacture of the brake disc make the brake disc in the non-braking state. During the braking process, the end face jump makes the contact area between the shoe and the disc uneven, resulting in fluctuations in the braking torque, which in turn produces brake jitter. The second is because the brake disc is in the continuous braking process The medium temperature rises, but the temperature distribution of the entire disc surface is uneven, and the change in the thickness of the brake disc caused by the difference in local thermal deformation causes brake vibration

The third is that the brakes are invaded by chemical substances during long-term use, which makes the distribution of friction and damping coefficients uneven on the disk surface, causing torque fluctuations during the braking process and resulting in brake vibrations

[0003] The road conditions in domestic cities are complicated and congested. Frequent use of brakes will cause the temperature of the brakes to rise, causing irreversible thermal distortion and deformation, which will cause brake vibration. Vehicles driving in mountainous areas will also have excessively high brake temperatures due to continuous long-term braking. Problems causing jitter

The current national standard GB21670-2008 "Technical Requirements and Test Methods for Braking Systems of Passenger Cars" has made detailed regulations on the braking performance test and evaluation of motor vehicles, but there is no provision for the test and evaluation methods of brake vibration. And, while the phenomenon of brake vibration of domestic vehicles in the process of use is an objective existence