Novel mechanism using differential gears for the electromechanical brake

Abstract

As is well known, the brake systems of vehicles are used in order to decelerate or stop the vehicle while the driving. The operational principle of the brake is the conversion of kinetic energy into thermal energy. In this case, the thermal energy is released to the atmosphere. Recently, electromechanical brakes (EMB) were developed in order to replace hydraulic brake calipers. Such brake-by- wire systems are composed of an electronic pedal, electronic control unit (ECU), wire, and an electromechanical caliper. A typical electromechanical brake is similar to existing floating brakes. In other words, an inner pad pushes out one side of a disc driven by the energy of a motor; by means of a screw-thread gear. Then, the caliper slides in the opposite direction by reaction force and moves the outer pad toward the other side of the disc. Then pads clamp both sides of the rotating disc and stop the wheel. While effective, this design has the problem that there is a difference in the wear of the inner and outer pads. In this paper, we describe a novel electromechanical brake design. Specifically, the proposed mechanism has some new features related to the presence of differential, and rack-pinion, gears. Furthermore, the wear difference of the inner and outer pads can be minimized by using our proposed mechanism. So to speak, both pads are clamped at the same time by the initial braking force. In addition, we focused on how to use the device to improve the braking force during the initial braking. Copyright © 2014 SAE International.