Bernd Piller

Electro-Mechanical Brake Systems

Electromechanical brake systems are already on the market as EPB (Electric Park Brake), in combination with conventional “wet” hydraulic service brake systems. In the future, so-called hybrid service brake systems will appear with the front axle still being hydraulically actuated and the rear axle having new “dry” electromechanical brake systems as a feasible “high-end” solution for advanced vehicles. 1 The EHCB System (Electric-Hydraulic Combined Brake, Hybrid Brake System) The EHCB system combines hydraulic servo front-wheel brakes with electromechanical power rearwheel brakes. The parking brake is fully integrated in the rear-wheel actuators (Electric Park Brake, EPB). 1.1 Objectives An electromechanical brake system (EMB) consumes less electric power in rear-wheel applications than in front-wheel applications, since lower levels of clamping force and dynamic responsiveness are required. This level of power consumption can be met with a conventional 12/14V electrical system. Many of the advantages of a fully brake-by-wire system, such as an integrated parking brake, variable brake force distribution between front and rear wheels, and software-based design, are achievable even with a hybrid – electrohydraulic combined brake (EHCB) – system. Such a system also offers better performance and comfort than conventional systems when it comes to implementing driver-independent braking requests, e.g., from driver assistance systems. On electric vehicles featuring braking energy recuperation using an electric motor/generator on the rear axle, the system can be configured for brake blending at the rear wheels. This system offers vehicle manufacturers a range of other advantages too. Since only the front brake is hydraulically actuated, it is possible to reduce the size of the actuator (vacuum brake booster) and thereby to significantly optimize the pedal feel characteristics. And since the electromechanical rear-wheel brakes are actuated independently of the hydraulic front-wheel brakes, it is possible to achieve better and more adaptable overall brake response characteristics. At the same time, the “dry” rear-wheel brake not only dispenses with hydraulic brake lines and hoses to the rear axle but also allows the axle to be preassembled using fully tested modules with simple interfaces. 1.2 System Architecture and Components At the front wheels, the EHCB system (Strutz et al. 2013; Stemmer et al. 2012) comprises a hydraulic singleor dual-circuit actuation system acting on conventional hydraulic brake calipers. The hydraulic system is adapted for single-axle braking. The driver’s wishes are identified by means of sensors at the *Email: bayercub@t-online.de *Email: bernward.bayer@continental-corporation.com Handbook of Driver Assistance Systems DOI 10.1007/978-3-319-09840-1_31-1 # Springer International Publishing Switzerland 2015