SENSOTRONIC BRAKE CONTROL

Introduction Introduction electronics necessary Sensotronic Brake Control (SBC) works electronically faster and more precisely large number of mechanical components are simply replaced by electronics Computer makes an exact calculation of the brake force necessary particular driving situation, calculates the optimum brake pressure for each wheel

Sensotronic Brake Control - the Brakes of the Future

What is Twin SBC ? Twin SBC system is based on the electro-hydraulic brake system that was recently introduced on the SL (R230) and E(W211) model The twin concept results in two SBC systems being utilized to provide vehicle braking

Units are located on the right and left side of the vehicle COMPONENTS OF SBC SBC Hydraulic Units Units are located on the right and left side of the vehicle Each unit has it’s own fluid reservoir Only use DOT 4+ brake fluid Do not overfill fluid reservoirs

Brake Operating Unit (BOU) • Located near the fire wall on the driver’s side of the vehicle • Incorporates the following: - fluid reservoir - two pedal value sensors - tandem master cylinder - brake pressure simulator

Front Axle Brake Calipers • Two calipers on each wheel • Fore and aft calipers are controlled by different control units • Insures brake force application at the front axle if there is a failure with one system • Square blocks on front calipers are used for vibration dampening

Rear Axle Brake Calipers • One caliper on each wheel • Calipers are split (top /bottom) • The top portion of each caliper is controlled by one SBC system • The bottom portion of each caliper is controlled by the other SBC system • Insures brake force application at the rear axle if there is a failure with one system

Electrical Components

Wheel Speed Sensors

Pedal Value Sensors • Located on the brake operating unit • Signals sent to SBC control modules to determine the amount of braking requested • Each sensor contains two hall effect sensors • Redundancy of sensor signals is monitored- if one sensor malfunctions, the value for the other will be used

Twin SBC Communication

One SBC System Failure Two SBC System Failures

Driving stability SBC once again offers the benefits of greater dynamics and precision: thanks to the even faster and more accurate braking impulses from the SBC high-pressure reservoir, ESP® is able to stabilize early and comfortably a vehicle which is about to break away This is evident, for example, from the results of the VDA lane-change test which suspension engineers use to simulate a quick obstacle-avoidance manoeuvre and to demonstrate the high capabilities of the Electronic Stability Program

Braking in a curve. Left: conventional. Right: with SBC

SBC Add-on Functions The so-called Soft-Stop function of the SBC software ensures particularly gentle and smooth stopping which provides significant comfort benefits particularly around town when you need to slow down frequently for traffic lights The Sensotronic Brake Control also incorporates a so-called Traffic Jam Assist function, which is activated using the cruise control stalk while the car is stationary On hills or steep drives the Sensotronic Brake Control Drive-Away Assist prevents the car from rolling backwards or forwards – stepping onto the brake pedal quickly but sharply is all it takes to activate the brake

SBC Incorporates these Functions ABS (Anti lock Brakes 1984) ASR (Automatic Slip Regulation 1991) ETS (Electronic Traction System 1995) ESP (Electronic Stability Program 1996) BAS (Brake Assist System 1998)

Driving with SBC - Wake-Up SBC is functional as soon as it is “wakened” by: opening a door (via CAN) operating the central locking system (via CAN) depressing the brake pedal turning key to position 1

The Chip Design SEM picture of the chip structure and X-ray picture of the bonded wafer showing the circular and square sensor design

Optimum deceleration during cornering Stabilization of the vehicle Advantages More stable braking Optimum deceleration during cornering Stabilization of the vehicle Shorter stopping distances Better brake response Even wear on brake pad linings

each wheel can be precisely controlled monitors release of accelerator pedal and application of brake faster response to brake request inputs

Conclusion Mechatronics – a new term is gaining popularity within the automotive industry Mechatronics brings together two disciplines which in many cases were thought to be irreconcilable, namely mechanics and electronics Hence automobile functions which hitherto worked purely mechanically and partly with hydraulic assistance will in future be controlled by high-performance microcomputers and electronically controllable actuators

References http://www.autospeed.com.au/ http://www.mercedes-benz.com/e/default.htm http://www.howstuffworks.com http://www.whnet.com/4x4/index.html

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