Development of a Self-Energizing Electro-Hydraulic Brake (SEHB)

A new hydraulic brake utilizing a self-energizing effect is developed at the Institute for Fluid Power Drives and Controls (IFAS). In addition to a conventional hydraulic braking actuator, it features a supporting cylinder conducting the braking forces into the vehicle undercarriage. The braking force pressurizes the fluid in the supporting cylinder and is the power source for pressure control of the actuator. The new brake needs no external hydraulic power supply. The only input is an electrical braking force reference signal from a superior control unit. One major advantage of the SEHB concept is the direct control of the actual braking torque despite friction coefficient changes.

The prototype design, presented in this paper, is done in two phases. The first prototype is based on an automotive brake caliper. It is set up to gain practical experience about the hydraulic self-energisation and to prepare the laboratory automation environment. Active retraction is required for train brakes though, which cannot be done with automotive brakes. The second prototype therefore features a differential double acting braking cylinder with a pre-stressed spring for fail safe braking. A mechanical design systematics is presented which helps to map requirement specifications originating from a particular application to implementation in a structural design. The promising dynamic behavior of SEHB based on simulation results is presented.