Development of the technology for reducing caliper drag torque

摘要

The brake judder caused by rotor thickness variation (cold judder) is a very important quality as well as the squeal noise, in the brake noise and vibration performance. The cold judder is a vibration phenomenon caused by the uneven rotor wear in the rotating direction. To reduce this uneven rotor wear, it is necessary to reduce the brake drag when the rotor rotating freely under non-braking condition. That is, the reduction of the brake drag relates to not only the fuel economy but also the noise and vibration performance importantly. In this study based on the fist type disc brake caliper, how the contact condition of the pads and the rotor affects the rotor wear was revealed first Then the relation between the behavior of the caliper and the drag torque was analyzed by measuring the displacement at several points of components together with the drag torque under non-braking mode. And it was verified that the drag was reduced effectively by the new caliper design based on these analytical results. This new type of caliper was named CLZ type (The current caliper is CL type) as the ultimate caliper which improved the noise and vibration performance of the current Colette type caliper. This caliper was applied to the front brake of a Nissan Moter's new passenger car in July 1998, and its application has been increasing successively.