Abstract
KEYWORDS – brake creep groan, suspension vibration characteristics, elastic kinematics of suspension, stick-slip motions, mechanism analysis
ABSTRACT
Creep groan noise is often generated when the brake pedal is slowly released in an automatictransmission car that is initially stationary; it can also be induced in a manual-transmission vehicle on an incline. The stick-slip phenomenon between the friction material and the rotor is the source of creep groan noise, which is caused by the difference between the static frictional coefficient and the dynamic frictional coefficient. Suspension characteristics are also significant contributors to creep groan. In fact, sometimes they are not just the transfer paths of the vibration, but also causes of it.
This paper describes the conditions leading to creep groan noise, as well as the objective characteristics of creep groan noise, which were discovered through road tests. To explain these characteristics, a quarter-vehicle creep groan model and a half-vehicle bow effect model were set up based on an improved Karnopp friction model. These models were used to simulate the conditions causing creep groan and to analyze the factors influencing creep groan. The results show that, in addition to the frictional characteristic, the suspension vibration characteristics, elastic kinematics of suspension, suspension attitude, traction force, and braking force distribution coefficient also influence the creep groan phenomenon.