Bosch ESP hev brake control system for hybrid and electric vehicles

In the future, large vehicles in particular will need electrified powertrains in order to comply with ever-stricter consumption limits. The efficiency of these hybrid and electric vehicles will in large part be determined by their ability to recover as much energy as possible while braking. Bosch’s ESP hev is the world’s first series-produced brake control system that coordinates the braking from the wheel and electric motor without the need for additional components, recovering a particularly high proportion of braking energy in the process. The system debuted in mid-2013 in the Mercedes-Benz S400 Hybrid. “Using ESP hev, all the braking maneuvers defined in the New European Driving Cycle (NEDC) can be fully exploited for energy recovery,” says Gerhard Steiger, president of the Bosch Chassis Systems Control division. “The new technology is part of our modular brake kit, with which we can put together a customized braking system for any vehicle.”High level of energy recovery thanks to decoupled axle
In the S400 Hybrid, the Bosch ESP hev coordinates the hydraulic and motor brake torque, and controls the electric vacuum pump of the vacuum-based brake booster. The brake circuit on the driven rear axle is decoupled from the driver’s foot. By deliberately giving the brake pedal greater play, the vehicle can initially be braked solely by the electric motor connected to the rear axle, generating electricity. The position of the pedal tells the system how much generator torque is needed. If the driver steps harder on the brakes, additional hydraulic brake torque is built up on the front axle in the usual way, so that braking force is now applied to both axles of the vehicle. If the generator cannot provide enough brake torque on the rear axle, the system uses the pump of the hydraulic modulator to build up additional brake pressure. The transitions are smooth and imperceptible for the driver – the vehicle’s behavior and pedal feel remain unchanged.

Along with the version described above for brake circuits with front and rear axle distribution, Bosch also offers a version for diagonal brake circuits. ESP hev can also be used in vehicles with front-wheel or four-wheel drive. The new braking system is based on ESP premium, the most powerful of the variants of Bosch Generation 9.

Modular kit offers the right braking system for every vehicle
ESP hev is part of a kit from which Bosch can put together a customized braking system for all vehicles and customer needs, taking criteria such as vehicle size, type of powertrain, degree of electrification, and number of assistance functions into consideration. While ESP hev is the regenerative braking solution for hybrid and electric vehicles, classic ESP continues to be the solution for conventional vehicles. There are also two brake-booster alternatives: the conventional vacuum-based solution and the iBooster. This new electromechanical brake booster does not need a vacuum, and in combination with ESP hev it can improve energy recovery even further – all the while providing excellent pedal feel. In addition, the iBooster offers the system redundancy that is essential for future automated driving functions. It will go into series production at the end of 2013. In other words, Bosch offers automakers an unrivaled modular and scalable solution package, which is especially suitable for vehicle models that are available with different powertrains.

Along with the ESP system, Bosch supplies other components for the different models of the new Mercedes-Benz S-Class, including the direct injection systems for gasoline and diesel engines, the display in the middle console, the start-stop starter, and the engine’s cooling fan.