Analysis And Control For Braking Noise Of Disc Brake

In recent years, more and more people take great concern about brake noises When developing new brake system, it's principal task for suppliers and Automotive factories to research, analyze and improve brake noise performance and also work for it in great efforts. Brake squeal is one kind of the most familiar noise, and the primarily concerned style of brake noise.What the paper bases on is practice and the product developing, and in the reducing cost project of one special vehicle, the schedule of changing aluminum knuckle to sphere graphite casting iron knuckle is approved. When the knuckle is assembled with the primary caliper and the brake disc, the brake squeal of the low frequency is found. The frequency of brake noise is 1.7 kHz and 1.8 kHz respectively in back condition, and the score is 2-3 points. The frequency of brake noise is 1.7 kHz, 2.7 kHz and 2.8 kHz respectively when car advancing, and the score are 4-5 points. And with increasing the cycles of brake, the brake noise is worse than before. And the result can't be accepted.For the purpose of the improving the brake squeal and avoid the complaint of consumers, it's necessary to change the structure of assembly of the brake. What the paper wants to describe is analyzing and improving the brake squeal of low frequency, which we face in the practice by experimentation method, so that the experience can be accumulated for the further work. The main content of the paper is as follows:(1) The test mode is analyzed by impact hammer for the main components, which influence brake squeal, such as housing of brake caliper, halter of brake caliper, lining and brake disc. And the inherent frequency and the mode are measured, and the frequencies, which produce brake noise, are analyzed, then the improvement is made.(2) By improving the technology of the brake caliper from cold press to stretch and rolling, the mass of the housing of the brake caliper is 150 g depressed and the frequency of the brake caliper is changed. After improvement, the inherent frequency is increased about 6.5%. And through the inertia test, the frequency of brake noise is 1.7 kHz and 1.8 kHz respectively in back condition, and the score is 2-3 points. The frequency of brake noise is 1.1 kHz, 1.6 kHz, 2.7 kHz and 2.8 kHz respectively when car advancing, and the score are 5-6 points. The conclusion can be drawn that it's less effects to improve the brake squeal if optimizing the structure of brake caliper.(3) Improving the structure of brake caliper halter (enhancing the quality and the rigidity), the mass of the halter of the brake caliper is 120 g increased. Through the inertia test, the frequency of brake noise is 1.7 kHz and 6.7 kHz respectively in back condition, and the score is 7-8 points. And There is no brake noise produced when car advancing. So the conclusion can be drawn that It can depresses the probability of the brake squeal. But at the same time, it's found that the squeal of high frequency occurs.(4) For the purpose of depressing the brake squeal of high frequency, the NAO friction material with low friction coefficient is adopted. And through the test, there is no brake noise produced in back condition. The frequency of brake noise is 1.78 kHz and 1.8 kHz respectively when car advancing, and the score are 5-6 points. So the conclusion can be drawn that not only the squeal of high frequency is depressing, but also the brake noise of low frequency is improved.(5) The road test of failure mode of brake booster which aims at the arrester with improvement (adopt the NAO friction material and improve halter of brake caliper) is done in terms of GB 12676-1999 5.26, and norm 5.26 requests that the test should be done in failure mode of brake booster, and the brake pedal force must be under 500 N, the average deceleration must be bigger than 2.9 m/s2. And result shows that the average deceleration is only 2.77 m/s2, and it can't meet the demand of the norm. After changing the diameter of the master cylinder from 23.81 mm to 22.22 mm, through the performance test, that the average deceleration is 3.11 m/s2, and the result shows that it can meet the demand of the norm.