-Intelligent control boosts braking power
-Basic system for electromobility and driver assistance
-Achieves greatest possible mileage by recuperating almost all braking energy in hybrid and electric vehicles
-Shortens braking distance in autonomous emergency braking by building up pressure three times faster
-Allows tailoring of brake pedal feel thanks to freely programmable characteristic curves
Press release:
In recent years, car braking systems have become ever more powerful. ABS and ESP in particular have significantly increased safety. Over the same period, however, the standard vacuum-based approach to boosting brake force has remained almost unchanged. Until now, there has been limited scope for recovering braking energy; and the driver's pedal force can only be amplified by a single predetermined degree. Now Bosch has developed the iBooster, an electromechanical brake booster that provides situation-dependent support when the driver initiates braking. “The iBooster makes hybrid and electric vehicles even more efficient, while enhancing safety through shorter braking distances,” says Gerhard Steiger, president of the Bosch Chassis Systems Control division. What is more, the iBooster complements a modular range of components from which Bosch can put together a suitable braking system for any vehicle configuration. Production of this innovation will start in 2013 for three series-produced models. Over the medium term, it will displace conventional brake boosters in many vehicles.
Increasing energy recovery to increase range:
If hybrid and electric vehicles are to achieve their intended range and fuel efficiency, they must recover as much electrical drive energy as possible when braking. Ideally, cars would be slowed down purely as a result of their electric motor converting their kinetic energy into electricity. This would avoid the loss of valuable energy through braking. The Bosch iBooster recovers almost all the energy lost in typical braking operations by ensuring deceleration rates of up to 0.3 g are achieved using the electric motor alone. It thus covers all common braking maneuvers in everyday traffic. If the brakes to be applied harder, the iBooster generates the additional braking pressure needed in the traditional way, using the brake master cylinder. The driver does not notice this harmonious interplay of motor and brakes, as pedal feel remains absolutely normal.
Bosch has integrated a motor into the iBooster to control the degree of brake boosting via a two-stage gear unit for situation-dependent support on demand. This dispenses with today's costly, continuous process of generating a vacuum using either the internal combustion engine directly or a vacuum pump. Not only does this save fuel in itself, it also allows more comprehensive use of fuel-saving functions that stop the engine for periods of time, such as start-stop or coasting.
More safety and more comfort:
The electromechanical concept offers further advantages. Should the predictive emergency braking system detect a dangerous situation, the iBooster can build up full braking pressure autonomously in a mere 120 milliseconds or so – three times faster than previous systems. In emergency situations, therefore, the iBooster can brake the vehicle faster than a driver using a conventional braking system. The iBooster can also take on the ACC's job of gently bringing the vehicle to a standstill, and do so comfortably and noiselessly. This is particularly compelling for quiet e-vehicles, since ambient sounds are much more noticeable in their interior.
The ability to define characteristic braking curves gives developers the freedom to determine pedal feel and adapt it to the customer's brand-specific wishes. If the vehicle also offers driving modes such as sport, comfort, or economy, the brakes can be made to react more softly or more aggressively as appropriate. Situation-dependent support is also possible, for instance during emergency braking.
Modular approach ensures suitability of braking system:
The iBooster is part of a modular range of components from which Bosch can easily put together a suitable braking system for all cars and all customer requirements – whatever the vehicle size, powertrain technology, and degree to which the vehicle is equipped with assistance functions. For brake boosting, the modular system offers the iBooster or the conventional, vacuum-based solution. For the brake control system, the choice is between a standard ESP or the ESP hev, which has been designed specifically for use in hybrid and electric vehicles. Especially for vehicle models that are offered with a choice of powertrain, this Bosch modular approach is so far unrivaled.
Increased flexibility for automakers:
As the number of different models and drive systems on offer rises, so too does the complexity of the underlying technology. Thanks to its freely programmable braking performance curve, identical Bosch iBoosters can be installed in different variants of a vehicle model and still offer tailored characteristics. Programming is quick and easy at the end of the production line, and it is easy to vary the installation to suit right-hand-drive or left-hand-drive models. The booster unit itself is purely electromechanical, without brake fluid, which means it can be rotated flexibly about the longitudinal axis. Consideration has also been given to the future of car driving: in combination with Bosch ESP, the system offers the level of braking-system redundancy that is needed for safety reasons in automated self-driving cars.
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