A Study on the Development of Brake Moan for CTBA Vehicles Using Simulation

Not only are customers' expectations for the development of various products, but also the demand for emotional quality improvement of the products is steadily increasing. Brake NVH, which is generated during vehicle braking, has a lot of influence on the emotional aspects of customers. There are several brake NVH such as judder, squeal, and moan. First, judder is phenomena of handle, brake pedal vibration and noise that occur during braking at the high-speed. The quality of judder has been improved a lot by applying judder detection and compensation logic in internal combustion engines and the heat load on the disc is reduced by regenerative braking in electric vehicles. So the judder problem hardly occurs these days. A squeal is a noise generated during braking at a low speed. The squeal is solved by tuning and shape change of a friction material in the high frequency band and by making the robust systems design such as caliper and disc in the low frequency band. Moan noise is low-frequency noise in the frequency band between 170 and 500 Hz and specially generated in vehicles equipped with rear CTBA specifications. But until now it is not easy to find the accurate generation mechanism and solution. The moan noise usually occurs both during braking and non-braking. During braking, the excitation force is generated by contact friction between the disc and the pad. During non-braking, the excitation force is generated by the brake drag which comes from the lateral force acting on the brake under the vehicle turning condition. This excitation force passes through the mounting bracket and spindle bracket and resonates the CTBA to generate moan noise. It is important to investigate for the more accurate generation mechanism and major influencing factors of moan noise. It is possible to increase the work efficiency of the vehicle engineers as well as improve customer satisfaction and vehicle quality if the major influencing factors are applied at the earlier vehicle development stage. In this study, the influencing factors that can reduce moan noise for vehicles with rear CTBA are investigated through the simulation and test as follows ① The development of moan noise analysis method ② The investigation of moan noise instability ③ The investigation of the caliper rigid body mode as the major influencing factor of moan noise and the control factors for caliper rigid body mode ④ The investigation of caliper rigid body mode by changing design parameter and also test verification will be investigated