상용차량의 브레이크 시스템과 차량 시스템 주파수 분석을 통한 브레이크 저더의 실험적 고찰

This paper studies experimentally on the building-up process for the amplitude of a commercial truck vibration induced by brake judder. A front axle drum equipped with a drum brake system is utilized for this experiment. A brake dynamo test, a real vehicle ride test and a real vehicle braking test are performed for the analysis of brake judder. The brake dynamo test measures judder by applying brake chamber pressures of 1, 2 and 3 bar at initial brake pad temperatures of 100℃ and 150℃. In order to assess the vertical acceleration at the front axle, the real vehicle ride test on a straight test road with velocities of 20, 40, 60 and 80 ㎞/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90㎞/h for evaluating the vertical, lateral and longitudinal accelerations both at the front axle and at the cab floor under the driver's seat. The magnitudes and frequencies of the measured peak accelerations from the brake dynamo test, the real vehicle ride test and the real vehicle braking test are comparatively analyzed. This paper shows that the vibration produced by brake judder is built up due to the brake system's peak acceleration frequency being close to the vehicle ride mode's frequency.