K 42 Volt Dry Brakeby Wire EMB Systems

K 42 Volt Dry Brake-by Wire (EMB) Systems Brakenet Workshop: Complex Electronic Braking Systems MIRA, September 12 th 2002 Presented by Michael Smith

K What is Dry Brake by Wire? • EMB replaces hydraulic fluid as the brake actuating medium and uses electric motors at each wheel to operate the calipers • EMB combines all the functions of ABS, TCS, EBC, ESP, BA, and parking brake

K What is Dry Brake by Wire? • EMB replaces vacuum servo, master cylinder, hydraulic fluid, systems and components, parking brake controls and linkages • No hoses and pipes, no hydraulic filling or bleeding at vehicle assembly plant • No hydraulic fluid related environmental issues during vehicle use or end of life recycling

K What does EMB offer? • • Improved braking and stability control Improved fuel consumption Reduced maintenance Overall weight reduction Improved under-bonnet packaging Simpler integration into other systems Potentially lower costs

K What are the drawbacks? • Requires 42 v power supply – But does not justify it • Complex system monitoring, fail safe and battery management systems • Increased unsprung weight

K Electrical Demand • Maximum peak demand is about 2 k. W for emergency application • This is required for up to 0. 2 secs after which 800 W maintains brake force • 2 k. W is needed for each cycle of ABS • Typical braking power is about 100 W on motorway and 40 W in town.

K Source: Conti. Teves

K Siemens EMB Prototype

K Bayern-Mechatronik EMB for High Speed Train

K Why 42 v for EMB? • Maximum power demand is 2 k. W – At 14 v this is 144 amp with unacceptable wire diameter, weight and cost – At 42 v it is reduced to 48 amp – 14 v weight penalty is 10 -15 kg • Need for EC brushless motors for performance, control and packaging • High temperature, high density electronic components

K Fail Safe Issues • If alternator fails there must be enough battery stored power to operate the brakes – Requires battery management system – Possibly additional dedicated battery – Limp-home facility?

K Fail Safe Issues • Requires continuous system monitoring and fault detection – High reliability bus protocol ensuring comprehensive fault tolerance – Deterministic time-triggered communications for system fault tolerance – Multiple micro controller units and digital signal processors

K Integration into 42 v net • EMB needs full time 42 v supply • Can be accommodated in 14/42 v dual voltage system • 42 v systems will be first introduced for energy saving and comfort and convenience systems • EMB will be added later.

K EMB Prospects • Needs 42 v to operate, so depends on 42 v availability. • Will not be a driver for 42 v but will use it to enhance braking and stability and other benefits • Development needs are management and control systems • Introduction likely 2006. European forecast, 1. 8 m vehicles in 2010

K Overall 42 volt Outlook • To meet increasing demand for electrical power – Cannot be achieved at 14 volts • To improve overall vehicle efficiency and meet demands for better fuel consumption and reduced emissions – Widespread efficiency gains with 42 volts

K Systems enabled by 42 volt power supply Integrated Starter Alternator --Stop/start operation --Acceleration boost --Regenerative braking EMV Electric cabin heating Electric powered air conditioning Windscreen de-icing Electric power steering (med and large cars) Electric oil and water pumps Exhaust Aftertreatment Suspension control Electromagnetic brakes

K Potential Electrical Demand (W)

K Potential savings in Fuel Consumption (%) with 42 volts

K 42 v Vehicle Electrical System Alternator 42 V Ctrl unit Power steering (300 W) Brakebywire Electrical valve timing Starter Seat Steering Fuel Windscreen Rear Windscreen ABS heating & wiper wheel pump defroster wipers pump (100 W) (500 W) (400 W) heating positioning (90 W) (600 W) (max. (120 W) 2000 W) DC Pyrotechn. gas gen. DC ISU Airbag Passenger Engine Lambda coolant sensor Water comp. fan heater pump blower (800 W) (40 W) (300 W) (500 W) To H. T. and spark plugs Valves Radio/ Cass ABS Instr. HVAC ECU 14 V Sidelights (4 * 5 W) Source: Siemens Dipped High (low) headbeam lights (2 * 65 W) (2 * 55 W) Rear fog lights (2 * 21 W) Reversing lights (2 * 21 W) Brake lights (2 * 21 W) Indicators (blinkers) (4 * 21 W) Interior light (25 W) Window Door Glove Windscreen lifters locks box light washers (4 * 350 W) (4 * 100 W) (10 W) (20 W) Fuel injector(s)

K European Outlook for 42 v Car Production • 2002 -3: special niche applications • 2004: 14/42 v by variant • 2006: introduction on new platforms • 2007: first 42 v only system • 2010: All new vehicles

K Starter Alternators Current Separate Components Combined Starter Alternators Fly wheel, Starter Alternator Clutch Gear box Engine Fly Wheel ECU Clutch Gear Box Engine Gear Belt Drive Fly wheel Starter Alternator Engine Transmission Starter Alternator ECU Clutch Gear box

K Batteries and Power Storage • Initially, lead acid batteries will be used • Stop/Start puts heavy demand on battery – 7, 000 starts goes up to 350, 000 per car life • Lithium Ion, or Lithium Polymer look like preferred technology – Spec power, spec energy, discharge cycles, packaging • Ultracapacitors may be introduced to handle acceleration boost and regenerative braking

K Power Distribution • Wiring harness weight savings frequently exaggerated • 42 v encourages multiplexing • Reduces connector problems • Requires more electronics in switches and circuit protection • Issues still to be addressed for dual voltage systems

K Motors • 42 volt motors would be more expensive than simple 14 v units – ie: those without speed or position control – very small motors eg: door locks, mirrors • 42 volt motors would be cheaper and more efficient than – Brushless 14 v motors – Motors with speed and position control • There would be modest benefits in weight and packaging

K 42 v: Implications for the Future • Major Technical Challenges – Electronics, Power storage and distribution • Major Industry Implications – Motor manufacture, Hydraulic Systems, Batteries, Lighting • Implications for Future Trends – Hybrids, Fuel Cells, Transmissions