Sensotronic Brake Control
The electro-hydraulic brake, or SBC ( sensotronic brake control ), a wheel brake, in which the hydraulic pressure for the wheel brakes is controlled by an electrical signal. This allows over conventional purely hydraulic braking systems a better controllability of the braking performance and thus depending on the situation a shorter braking distance.
- 3.1 comfort
Operation
In the electro-hydraulic brake, the rider's wishes are recorded electronically by a sensor technology. In this case, a displacement sensor detects the temporal profile of the pedal travel and the pedal speed thereof and the acceleration. In addition, is detected by a pressure sensor of the pressure variation in the control circuit. It directs the control unit from the driver's request ( partial braking, emergency braking, and so on ), and calculates the required in the current driving situation, the target pressure for each wheel brake. The control unit controls a hydraulic unit that can build an individual brake pressure for each wheel. Pressure sensors in each Radleitung determine the actual pressure, so that the desired pressure for each wheel can be adjusted individually.
The required for the supply of brake pressure generated by a high pressure pump, a pressure accumulator is to one side. The accumulator holds enough energy supply in order to decelerate the vehicle even upon failure of the pump at least once to a stop in the form of a compressed gas. Often even comes with an electrical energy storage capacitors used, which in case of failure of the on-board voltage can still provide a certain amount of time the system.
In contrast to the conventional braking system, the driver has no direct sensory contact with the wheel brakes more in this system. A "simulator" produces the well-known brake pedal feeling, which is caused as a counter force in conventional brakes by the hydraulic pressure of the oil column from the master cylinder to the wheel brakes. In case of failure of the control system is via valves as in a conventional brake a direct - connection established between the master cylinder and the wheel cylinders of front axle - but unreinforced.
Benefits
Security
The electro-hydraulic brake enables shorter braking distances by optimum utilization of the dynamic axle load shift (electronic suspension ) and faster brake response.
Another advantage is that the pulsating reaction is attributable to the pedal when ABS control. Studies have shown that often reduce vehicle driver in horror at the pulsating brake pedal, the brake force and so give braking distance. This behavior can be prevented by the use of electro-hydraulic brake.
Disadvantages
Unlike conventional brake system, the system of electrical energy depends. Failure of the power supply also lead to brake failure. The brake goes into emergency mode. The vehicle is then practically unusable.
Depending on certain parameters such as number of braking operations, frequency of brake fluid change, etc. Software calculates the vehicle that the SBC pump may be defective and turns the car into a limp, if the unit is not replaced (1600 € as of 2012). When the exchange is pending, is not visible to the user. However, this is just for the used-vehicle market is important.
Important! For electro- hydraulic brake systems, the automatic coating application routine must be disabled before the exchange of wear parts such as brake discs and brake pads. If this fails, it may occur during the installation to a system-dependent automatic pressure build-up and the mechanic seriously hurt.
Comfort
In addition to increased traffic safety can be realized with electro-hydraulic brake systems convenience functions that are associated with conventional brakes harder or impossible. Especially the sensotronic Brake Control ( SBC) system, called Mercedes- Benz has extensive additional functions:
Once precipitation is detected, the SBC applies the brake pads at regular intervals to the disc in order to remove the film of water adhering to it and " trockenzubremsen " the disc so. In addition, the SBC applies the brake pads against the disc, when the driver suddenly from the gas, so as to achieve the best possible delay in any subsequent emergency braking.
In addition, the SBC system has two SBC Hold and SBC Stop functions mentioned. The SBC - hold function is to secure the vehicle when stopped and engine running ( for example, waiting at traffic lights ) against rolling and to simplify hill starts much. It is sufficient to enter the brake pedal firmly once. Deactivated it is created automatically when the accelerator and again, passage of the brake with the same pedal travel. SBC- Stop is a stop-and -go assistant, which is activated by means of cruise control switch and up to a speed of 60 km / h, the brakes automatically takes over. This is done with a constant, relatively high delay and without inclusion of additional sensors. SBC- stop was in the E-Class ( 211 series ), only the first almost two model years available and was thereafter removed without replacement.
Furthermore enables an electro-hydraulic brake in electric or hybrid vehicles, such as the Toyota Prius to convert kinetic energy into electrical energy which is fed into the accumulator, rather than turn them over the brake discs into useless heat. Only after long delays and at low speeds is braked by the brake discs.
Use
The first electro-hydraulic brake for vehicles has been by the Japanese company Advics presented (a subsidiary of Toyota) in spring 2001 at the Toyota Estima Hybrid. She was only available on the Japanese market.
The first globally available electro-hydraulic brake was developed by the Robert Bosch GmbH together with DaimlerChrysler and presented in September 2001 at the IAA in Frankfurt to the public. It is as sensotronic Brake Control in Mercedes- Benz vehicles by type SL (R 230), SLR ( R 199), in the E-Class ( W 211 / S 211), the Mercedes CLS ( C 219 ), and in the Maybach 57 and 62 (W 240/ 240 V ) in use. A special two units are the Maybach used so that two redundant braking circuits are present.
Because of errors in the electrohydraulic brake system Mercedes -Benz had to call back in May 2004 about 680,000 vehicles in the E- and SL-Class. Other difficulties with the first as a " Super brake" titulierten system in 2005 led to one of the largest product recalls in automotive history. Worldwide had about 1.3 million Mercedes E, CLS and SL-Class in the workshop. With the facelift 2006 Mercedes turned away at the E-Class and CLS -Class of the SBC and returned to the conventional braking system. In the SL and Maybach vehicles SBC is, however, still installed (July 2007).
Continental Teves presented in 2000, a test vehicle with a comparable system in a modified VW Golf before, which had 100 km / h braking distance of 30 m. This corresponds to a deceleration of 12.86 m s-2 - usual time were 38.5 m and 10.02 m braking distance s 2 deceleration. In the U.S., an electrohydraulic brake system from Continental Teves since 2003 in the Ford Escape Hybrid in production use.
Toyota developed the first generation of its electro-hydraulic brake ( ECB) on and put the ECB II for model 2003/ 2004 Toyota Prius II before. In the Prius II, this technology has proven so far and there are no failures become known.
When Toyota subsidiary Lexus also comes the electro-hydraulic brake of Advics in the CT 200h, RX 400h, GS 450h, LS 460 and LS 600h used.
Launch
April 2001: ECB of Toyota Estima Hybrid in Advics (Japan)
September 2001: SBC Bosch at the Mercedes- Benz SL 500
2003: EHB by Continental Teves in the Ford Escape Hybrid (USA)
December 2003: ECB II of Advics in the Toyota Prius II