K 42 Volt Dry Brake-by Wire (EMB) Systems Brakenet Workshop: Complex Electronic Braking Systems...
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Transcript of K 42 Volt Dry Brake-by Wire (EMB) Systems Brakenet Workshop: Complex Electronic Braking Systems...
K42 Volt Dry Brake-by Wire
(EMB) Systems
Brakenet Workshop:Complex Electronic Braking Systems
MIRA, September 12th 2002
Presented by
Michael Smith
KWhat 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
KWhat 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
KWhat 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
KWhat are the drawbacks?
• Requires 42v power supply– But does not justify it
• Complex system monitoring, fail safe and battery management systems
• Increased unsprung weight
KElectrical Demand
• Maximum peak demand is about 2kW for emergency application
• This is required for up to 0.2 secs after which 800 W maintains brake force
• 2kW is needed for each cycle of ABS• Typical braking power is about 100W
on motorway and 40W in town.
KWhy 42v for EMB?
• Maximum power demand is 2kW– At 14v this is 144 amp with unacceptable
wire diameter, weight and cost– At 42v it is reduced to 48 amp– 14v weight penalty is 10-15kg
• Need for EC brushless motors for performance, control and packaging
• High temperature, high density electronic components
KFail 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?
KFail 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
KIntegration into 42v net
• EMB needs full time 42v supply• Can be accommodated in 14/42v
dual voltage system• 42v systems will be first
introduced for energy saving and comfort and convenience systems
• EMB will be added later.
KEMB Prospects
• Needs 42v to operate, so depends on 42v availability.
• Will not be a driver for 42v but will use it to enhance braking and stability and other benefits
• Development needs are management and control systems
• Introduction likely 2006. European forecast, 1.8m vehicles in 2010
KOverall 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
Electric power steering (med and large cars)
Electric cabin heating
Electric powered air conditioning
Electromagnetic brakes
EMVIntegrated Starter Alternator--Stop/start operation--Acceleration boost--Regenerative braking
Windscreen de-icing
Electric oiland water pumps
Suspension control
Exhaust Aftertreatment
K Potential Electrical Demand (W)
Under Bonnet Interior BodyEPAS 1000 Heated screen 1000 EMB 250-2000
EMV 2000 Heated seats 600 Suspension 3000
Water pump 200-800
Int heating 3000 Heated Cat 3000
AC Comp 3000 ICEC 800 Wiper motor <300
EC fan 300-800 Body motors <300
Oil pump 500 Lighting 200
K Potential savings in Fuel Consumption (%) with 42 volts
0
2
4
6
8
10
12
14
16
%
ISA
EMV
EPAS
Stop/Start
Water pump
K 42v Vehicle Electrical System
14V
42V
DC
DC
Ctrl unit Ctrl unit Ctrl unit Ctrl unit
Alternator
Starter
Fuelpump
(100W)
Reardefroster(400W)
Windscreendefroster(500W)
Seatheating &
positioning(max.
2000W)
Windscreenwipers(90W)
Rearwiper(90W)
ABSpump
(600W)
Powersteering(300W)
Brake-by-wire
Electricalvalvetiming
Passengercomp.blower(500W)
Enginecoolant
fan(800W)
Lambdasensorheater(40W)
Waterpump
(300W)
Side-lights
(4 * 5W)
Dipped(low) head-
lights(2 * 55W)
Highbeam
(2 * 65W)
Rearfog
lights(2 * 21W)
Reversinglights
(2 * 21W)
Brakelights
(2 * 21W)
Indicators(blinkers)(4 * 21W)
Fuelinjector(s)
Interiorlight
(25W)
Glovebox light(10W)
Windscreenwashers(20W)
Windowlifters
(4 * 350W)
Doorlocks
(4 * 100W)
ISU Airbag ABS Radio/Cass
Instr. HVAC ECU
ValvesPyrotechn.gas gen.
To H.T.and spark plugs
Steeringwheel
heating(120W)
Source: Siemens
K European Outlook for 42v Car Production
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
2000 2002 2004 2006 2008 2010
Pro
duct
ion
(000
s)
• 2002-3: special niche applications
• 2004: 14/42v by variant
• 2006: introduction on new platforms
• 2007: first 42v only system
• 2010: All new vehicles
K Starter Alternators
Alter-nator
Starter
Gear
Engine
GearBox
Belt Drive
Fly Wheel Clutch
Current Separate Components
Engine
Fly wheel, Starter
Alternator
ECU
Clutch
Gearbox
ECU
StarterAlternator
Engine
Gearbox
Fly wheel Clutch
Combined Starter Alternators
Trans-mission
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
• 42v 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 14v 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 14v motors– Motors with speed and position control
• There would be modest benefits in weight and packaging