The higher brake performance is required for vehicle safety. At the same time, the mass reduction of brake system is especially required for vehicle economic long run performance with lower fuel consumption. Under these backgrounds, higher friction pad materials come to be adopted for brake system in vehicle. But it is well known that pad materials with higher friction coefficient sometimes cause brake noise problems. Therefore it is very important technical issue to reduce brake noises for vehicle with higher brake performance and economic long run with lower fuel consumption.
Many papers have been ever presented for brake squeal, moan noise, creep groan noise and so on. Today it is required in brake design to consider the influences of countermeasure for every brake noise, because moan noise countermeasure sometimes causes low-frequency disk brake squeal for example. The countermeasure should be derived from the analysis for reducing all brake noises, but there is almost no paper of the relationship research between each brake noise. This paper describes the importance of every brake noise relationship, for example, the relationship between low-frequency disk brake squeal and moan noise.
Low-frequency disk brake squeal around 2 kHz was analyzed before. First, the equation of motion for low-frequency disk brake squeal is given by 4 degrees of freedom of calliper with suspension and brake disk. This equation of motion shows the influences of the friction coefficient of pad materials, the contact condition between disk and pad, and the natural frequencies of calliper with suspension and brake disk. Moan noise around 300 Hz was also analyzed before. Secondly, the equation of motion for moan noise is given by 2 degrees of freedom of calliper with suspension. This equation of motion shows the influences of the friction coefficient of pad materials, the contact condition between disk and pad, and the natural frequency of calliper with suspension.
Moan noise is not influenced by the natural frequency of brake disk, because of sufficiently small amplitude of brake disk during moan noise generation. Moan noise gives us the different phenomena impression from low-frequency disk brake squeal.
This paper describes that moan noise is one of the dynamic instable solutions of lowfrequency disk brake squeal, given by 4 degrees of freedom of calliper with suspension and brake disk. When the system has lower stiffness of calliper support, the vibration amplitude of disk is sufficiently small and the amplitude of disk is considered to be negligible. Then the equation of motion is reduced into 2 degrees of freedom, which gives the equation of motion in moan noise. This consideration enables us to reduce moan noise and low-frequency disk brake squeal at the same time.
Nishiwaki, Masaaki* - Teikyo University Langthjem, Mikael A - Yamagata University