Prius Primer

L. David RoperProfessor Emeritus of Physics

Virginia Polytechnic Inst. & St. Univ.roperld@vt.edu

http://arts.bev.net/roperldavid

Toyota Prius II 2004-8($21,000 to $30,000)

A serial-parallel (full) hybrid A serial-parallel (full) hybrid (gasoline + electric) car(gasoline + electric) car

http://www.hybridsynergydrive.com/en/top.html

Prius 2004-8 Under the Hood

Engine Generator/motor Motor/generator

Inverter UnitFuse box Fuse box

with with jump-start jump-start terminalsterminals

4 cylinder4 cylinder engine + electric motors = engine + electric motors = 6 cylinder6 cylinder engine performance. engine performance.

Hood Hood bracebrace

Aluminum hoodAluminum hood

Toyota Prius 2004-6

Motion selectorMotion selector

Power buttonPower button

8-feet ladder (not included)8-feet ladder (not included)

2005 Fastest selling car in the U.S.2005 Fastest selling car in the U.S.

Energy-Use Energy-Use 7” Display7” Display

generator/motorgenerator/motor

Motor/generatorMotor/generator

201.6-VoltsTraction battery 12-Volts system-start/accessories battery201.6-VoltsTraction battery 12-Volts system-start/accessories battery

““Key” fob slotKey” fob slot

Prius Cargo Areas

Small-items storage

Back seats downPull up extra space cover to make room for large suitcases.Pull up extra space cover to make room for large suitcases.False spare tire & tools are under storage bin.False spare tire & tools are under storage bin.Remove storage bin to get to 12V system-start/accessories battery on Remove storage bin to get to 12V system-start/accessories battery on right side .right side .

Cargo coverCargo cover

3’ 3” by 5’ 9” long

Prius Cargo Area

Split back seat

False False spare tire spare tire

& jack& jack

Cargo box Cargo box & tire & tire toolstools

Front tow hook.Front tow hook.

Maps & Maps & bottle bottle holder holder (both (both sides)sides)

Traction BatteryTraction BatteryBattery safety plugBattery safety plug

Small Small storage storage

binbin

12-Volts system-start/accessories battery12-Volts system-start/accessories battery

Toyota Prius 2004-6

Motion Motion selectorselectorTo start hybrid system, depress brake To start hybrid system, depress brake

pedal before pressing Power once.pedal before pressing Power once.

Smart Start option: fob can be anywhere in the car.

Smart EntrySmart EntryAlso, audio.Also, audio.

7” Multi-Display• Can be turned off (Display/Screen off)• Has daytime and nighttime settings (dark

background).• Nighttime settings are in effect when lights are

on, except when panel dimmer wheel is set to maximum.

• Can save settings for different users.• Outside temperature is shown when energy

display is active.• Several display controls are on the steering

wheel. Holding a button done turns on and off.• Audio and air conditioning controls can be

displayed, but some are also available on the dash and steering wheel.

http://john1701a.com/prius/presentations/2004-prius_tech-presentation_01.htm

Rear tie down hooks; can be replaced by tow bar for rear bicycle rack.Rear tie down hooks; can be replaced by tow bar for rear bicycle rack.

Emissions controlsEmissions controlsOil filterOil filter Oil drainOil drain

Note the flat plates to cut down on drag at high speeds.Note the flat plates to cut down on drag at high speeds.

Front of vehicleFront of vehicle

Whats Underneath.Whats Underneath.

Toyota 2004-8 Prius Specifications• Engine: 1.497 cc, 4 cyl, 16 valves, VVT-i, ETCS-i, 76 hp (57

kW) @ 5000 rpm, compression ratio 13.0/1• Motor/generator: 500-Volts Permanent Magnet rotor AC

Sync, 67 hp (50 kW) @ 1200-1540 rpm• Generator/motor: 500-Volts PM AC Sync, 34 hp (25 kW).

Starts engine at 1000 rpm when needed. Can turn up to 10,000 rpm. A crucial part of the Electronic Continuous Variable Transmission (ECVT).

• Power Split Device: fixed gears that connect engine, motor/generator & generator/motor to provide the ECVT by electronic control.

• Traction Battery: 201.6-Volts NiMH, 38 kW (51 hp)• 5 networked hybrid system computers.• Net Hybrid System power: 110 hp (82 kW)• Heated coolant when starting• Regenerative coasting and braking• Realistic Mileage: 40-55 mpg (EPA: 60 city/51 not so)

1 hp = 0.746 kW1 hp = 0.746 kW1 kW = 1.34 hp1 kW = 1.34 hp

Toyota 2004-8 Prius Specifications• Weight: 2890 lb (~$10/lb with all options.)• People and cargo capacity: 825 lbs (374 kg)• Turning radius: 17 feet (Turns around within most streets.)• Coefficient of drag: 0.26 (Only Honda Insight is lower.)• Ground clearance: 4.9 inches (Not an SUV!)• Height/width/length: 58.1/67.9/175 inches• Electric: reverse motion, initial motion, climate control,

steering, braking• Interior: size of Toyota Camry• Exterior: size of Toyota Corolla• 12-Volts battery to start system & for accessories• Tires: P185/65R15 Goodyear Integrity (low snow traction)• 11.9 gal = 450-500 miles per tank• Uses 87 octane gasoline with up to 10% ethanol• 0-60 mph in 10.1 seconds• Top speed: 103 mph

Toyota 2004-8 Prius Specifications• Air bags: 2 standard; 4 more as extras• Energy-use, climate control and audio 7” display• Tilt steering wheel• Warranty: Basic: 3 yrs/36 kmi; Hybrid system: 8 yrs/100

kmi; Power train: 5 yrs/60 kmi; Rust-through: 5 yrs/unlimited mi; Accessories purchased with car: 3 yrs/36 kmi. Road side assistance and hazard insurance: 3 yrs/36 kmi

• Excellent navigation system and wireless Bluetooth phone connection as an option

• Seats are cloth or leather. Toyota has seat covers that are easy to install, with 2 map pockets for each front seat. (2006 model offers leather seats.)

• Classified as a mid-sized car.

Standard Features ($23,000)• Micron-filter 201V electric air conditioner• Power windows and door locks• Heated outside mirrors and rear window• Remote keyless entry• Cruise control• 6-speaker AM/FM/CD stereo• Anti-lock brakes with electronic assist• Traction control• Multi-stage dual front air bags• Illuminated sun-visor mirrors• Self-leveling headlights• Much storage space for small items.

Optional Features ($30,000)• Front side and roll-sensing curtain air bags (front & back)• Intermittent rear window wiper• Key-less entry & start system (Smart Key)• Vehicle stability control (Automatically controls brakes and

hybrid system to prevent skidding when cornering on a slippery road or turning steering wheel abruptly. There is a slip-indicator icon in dash display.)

• High-intensity discharge headlamps• Integrated fog lamps• Homelink remote transmitter on auto-dimming mirror• 9-speaker AM/FM/Cassette/6-CD stereo• Immobilizing security alarm• Floor and cargo mats; cargo net• DVD Navigation system with voice activation• Bluetooth wireless telephone connection

How Does It Achieve Fuel Efficiency?• Because of electric motor assistance, the engine can

run at peak efficiency more often.• Electric motors are more efficient than gasoline

engines over a larger range of rpm.• The high voltage (500 V) for the motors/generators

cuts down resistance loss.• Deceleration and braking recharge the battery.• The engine shuts off when not needed; for example,

at stops and down hill. It then instantly restarts when needed.

• The engine receives hot coolant before starting, which enhances efficiency. Starts at 1000 rpm.

• The body is aerodynamically designed for low drag (0.26 drag coefficient).

Aerodynamics Underneath

http://privatenrg.com

Air Flow Around a Prius II

Location: Location: MinnesotaMinnesota. Mix of . Mix of city, suburban & highwaycity, suburban & highway driving. driving.http://john1701a.com/prius/prius-data10.htm

2004 Prius mpg Versus Month of Year2004 Prius mpg Versus Month of Year

12 mpg difference between January and June driving in

Minnesota. I guess 6 in Virginia.

Total Cost of a Prius• The Prius hybrid system has no clutches or friction bands to wear

out, contrary to the case for a gasoline car. There is nothing in the hybrid system to wear out except gears and bearings. The hybrid system should last for at least 500,000 miles if properly maintained.

• The engine is not stressed nearly as much as one is in a gasoline car. So, the engine should last for over 200,000 miles if properly maintained.

• The electric motors are brushless designs, so they should last for 500,000 miles if properly maintained.

• Regenerative braking greatly delays brake pad and rotor wear. So, the brakes should last for more than 100,000 miles.

• So, cost effectiveness of driving a Prius is as much due to the longevity of the hybrid system, the gasoline engine, the electric motors and the brakes as it is due to higher mpg.

• As important as high mpg is the low emissions of a Prius compared to any gasoline car. High mpg for a gasoline car does not equate to low emissions. A gasoline car optimized for low emissions usually has high mpg, but it sacrifices performance. Performance is not sacrificed in a Prius.

How Does the Prius Achieve Low Emissions?• Since it uses less fuel, it produces less emissions.• Because of electric motor assistance, the engine can run

at peak efficiency more often, which makes emissions lower.

• The engine design (Atkinson cycle, cylinder shape, fuel injection and variable firing timing) is aimed at low NOx emissions.

• The engine shuts off when not needed; at stops and going down hills. It then instantly restarts when needed. This reduces emissions.

• The engine receives hot coolant before starting, which reduces NOx emissions.

• Has bladder-lined gasoline tank to eliminate escaping fumes. (Makes it difficult to manually calculate mpg.)

• Has lowest emissions rating of any gasoline vehicle.

Bladder-Lined Gasoline Tank• Gasoline tank has a plastic bladder liner, which

expands and contracts as gasoline is added and used. This minimized evaporative losses into the environment.

• The bladder can become less flexible in cooler weather, which will keep you from putting a full 11.9 gallons in the tank.

• The bladder makes the fuel gauge (“guess” gauge) not very accurate. Always refuel when or before the last marker shows on the fuel gauge.

• Filling a nearly empty tank with less than 3 gallons will not register on the fuel gauge.

• http://i50.photobucket.com/albums/f322/fixmyset/refueling.swf

http://www.toyota.co.jp/en/k_forum/tenji/pdf/pgr_e.pdf

Drive it Drive it another another

100,000 kms 100,000 kms and watch and watch

these these differences differences

grow.grow.

Based on 10-Based on 10-years use and years use and 100,000 km 100,000 km

(62,000 miles).(62,000 miles).

Prius Life-Cycle Carbon Dioxide Emissions

1 km = 0.62 mi: 20,000 km = 12,400 mi; 100,000 km = 62,000 mi1 km = 0.62 mi: 20,000 km = 12,400 mi; 100,000 km = 62,000 mihttp://www.toyota.co.jp/en/k_forum/tenji/pdf/pgr_e.pdf

Toyota Prius 2004-2005A series-parallel full hybrid (gasoline + electric) car

The power split device (PSD) can be regarded as an asymmetrical differential, for which the two motor/generators are analogous to the two wheels that connect to a conventional differential and the engine is analogous to the crank shaft (reduction gears in the Prius) going into a conventional differential.

http://www.ecrostech.com/prius/original/PriusFrames.htm

DCDC

ACAC ACAC

AC->DCAC->DCDC->ACDC->AC

AC->DCAC->DCDC->ACDC->AC

Engine shaft Engine shaft goes through goes through MG1 shaft to MG1 shaft to the planetary the planetary carrier of the carrier of the

PSD.PSD.

Toyota Prius 2004-5 Power System

Power-split devicePower-split device

Prius Power Systemhttp://www.privatenrg.com

Large Large motor/ motor/

generatorgenerator

Power Split Power Split DeviceDevice

Small Small generator/ generator/

motormotor

Toyota Prius 2004-5 Power Split Device

Power Split DevicePower Split Device: : 7878 teeth in ring gear, teeth in ring gear, 3030 teeth in sun teeth in sun gear, 23 teeth in each planet/pinion gear. (Also called gear, 23 teeth in each planet/pinion gear. (Also called planetary gearsplanetary gears, , epicycle gearsepicycle gears and and trans-axletrans-axle.).)

http://homepage.mac.com/inachan/prius/planet_e.html

Prius Power Split Device (PSD)

Sun gear:Sun gear:MG1MG1

Ring gear:Ring gear:MG2 & WheelsMG2 & Wheels

Planet/pinion Planet/pinion gearsgears

Planetary carrier:Planetary carrier:EngineEngine

Notice how small it Notice how small it is!is!

Effectively, this and Effectively, this and the electronics the electronics comprise the comprise the

continuously variable continuously variable “transmission” of the “transmission” of the Hybrid Synergy Drive.Hybrid Synergy Drive.

Toyota Prius Hybrid Synergy Drive Control

This contains the DC/AC inverters. Notice the orange power cables to the traction battery and to the motor/generator and the generator/motor.

The 5 computers are located at different places in the car. It is a “drive by wire” system similar to modern airplanes.

Effective Hybrid Transmission• The Prius does not have a "true" transmission,

instead the gear ratios are fixed. One can accelerate from zero to the maximum speed in one gear; however engine torque is not multiplied by a transmission. This lack of low-end engine torque is replaced by a large electric motor/generator and a smaller generator/motor, which are connected to the engine in a planetary gear arrangement (Power Split Device).

• The onboard computer shifts power from the engine and to and from (using the traction battery’s power) the motor/generators, determining the most efficient use of the engine and/or the electric motor/generators based on driving conditions, accessories in use and when to charge the battery.

Movement of Power-Split Device Gears

Moving in Reverse Starting Engine at Rest

Accelerating & Hill Climbing Cruising Coasting & braking

Two cases Two cases when the when the engine is not engine is not runningrunning..

2004-5 Toyota Prius 201.6-Volts Battery

Under the backseat with cooling vent beside the seat.Under the backseat with cooling vent beside the seat.• 28 sealed modules of six NiMH 1.2-Volts cells per module. 6.5 Amp-hours.28 sealed modules of six NiMH 1.2-Volts cells per module. 6.5 Amp-hours.• Weighs Weighs 86 lb86 lb (39 kg). Highest output per weight in the world (1300 W/kg). (39 kg). Highest output per weight in the world (1300 W/kg).• Charge ranges from Charge ranges from 40% to 80%40% to 80% of maximum, usually 50% to 70%. of maximum, usually 50% to 70%.• Alkaline electrolyte is Alkaline electrolyte is a gel that will not leak, even in a collisiona gel that will not leak, even in a collision..• Sealed in a steel case electrically isolated from battery terminals.Sealed in a steel case electrically isolated from battery terminals.• Each module is Each module is vented underneathvented underneath in case of overcharge gas release. in case of overcharge gas release.• All components are All components are recyclablerecyclable..• Incentive of $200 for each battery returned for recycling.Incentive of $200 for each battery returned for recycling.• Guaranteed for Guaranteed for 8 years or 100,000 miles8 years or 100,000 miles (10 years/150,000 in California). (10 years/150,000 in California).

Battery safety plug/fuse

1.31 kWh1.31 kWh

Prius Battery Module & Safety Plug/Fuse

• Note the six NiMH 1.2 Volts Note the six NiMH 1.2 Volts cells.cells.• Note the electrical Note the electrical connectors on the ends.connectors on the ends.• Note the overcharge gas Note the overcharge gas vent at the bottom left.vent at the bottom left.

Battery safety Battery safety plug and fuseplug and fuse

http://www.peve.panasonic.co.jp/catalog/e_kaku.html

Charging the Battery at Rest• Stop the car and set the parking brake firmly.• Firmly press the brake pedal.• Set the motion selector to “D”.• Press the accelerator pedal most or all of the way down.

(Only the small generator/motor is charging the battery, since the large motor/generator is at rest with the wheels. This is the reverse of starting the engine at rest.)

• The battery will be fully charged in about 5 minutes or less.

• You might want to do this before climbing or at a rest stop on a long, steep hill for which the battery eventually will run out of charge and, thus, does not supply power to the motor.

Prius 12-Volts Battery Turns the hybrid system on by actuating contact relays.Turns the hybrid system on by actuating contact relays. Provides power for the five computers and the networks in the car.Provides power for the five computers and the networks in the car. Provides power for the accessories.Provides power for the accessories. Charged by the traction battery. Can be jump-started by other 12-Volts batteries Charged by the traction battery. Can be jump-started by other 12-Volts batteries

by using by using terminals in the fuse box under left side of hoodterminals in the fuse box under left side of hood. (When jump-starting . (When jump-starting other vehicles, best to charge the other battery from the Prius battery, other vehicles, best to charge the other battery from the Prius battery, disconnect the jump and then start the other vehicle.) If the 12-Volts battery disconnect the jump and then start the other vehicle.) If the 12-Volts battery becomes discharged, you cannot move the Prius with its front wheels on the becomes discharged, you cannot move the Prius with its front wheels on the ground, because it is in PARK.ground, because it is in PARK.

Will gradually discharge when car is dormant. Decrease the discharge by Will gradually discharge when car is dormant. Decrease the discharge by turning turning off the smart-key switchoff the smart-key switch under the steering wheel. For longer dormancy periods under the steering wheel. For longer dormancy periods use a use a BatteryMINDerBatteryMINDer ( (https://www.batteryweb.com/batteryminder.cfm) or ) or disconnect the cable from the positive jump-start terminal in the fuse box on the disconnect the cable from the positive jump-start terminal in the fuse box on the right under the hood (and lose memory settings). You can buy a VW solar battery right under the hood (and lose memory settings). You can buy a VW solar battery charger on eBay for parking the Prius outside for long periods.charger on eBay for parking the Prius outside for long periods.

Batteries maintenance: Batteries maintenance: http://www.vfaq.net/docs/TSBs/PG007-03.pdf

Locations of Prius Batteries This is a wrecked Prius that will be shown in more detail later. Notice the orange power cable on the left side and the small 12-V battery at the right rear. There are connections for the 12-V battery under the hood for jump starting.

Traction battery

Battery cooler

http://www.autobeyours.com/05%20Prius.htm

Prius Gasoline Engine• 1.497 cc, 76 hp (57 kW) @ 5000 rpm, 82 lb-ft (111 N-m) @

4200 rpm, 4 cyl, 16 valves, VVT-i=Variable Valve Timing-intelligent, ETCS-i=Electronic Throttle Control-intelligent, compression ratio 13.0/1

• Aluminum alloy• Atkinson/Miller cycle: short compression stroke (Valves do not

close until after the end of expansion stroke.)• Offset crank shaft allows straight down power stroke.• 3 liters of Heated coolant stored near boiling point for 3 days

used to preheat the engine before starting.• Engine stopped at precise point in cycle to minimize stress

when restarted.• Engine is cranked to 1000 rpm and oil pressure established

before spark is applied first to 2 of the 4 cylinders. This takes about ½ second.

• Variable valve timing to optimize efficiency.• Unique air intake system to reduce manifold friction.

2004/6 Prius Gasoline Engine

http://www.privatenrg.com

http://www.toyota.com/html/hybridsynergyview/2005/fall/mpgs.html

http://www.cleangreencar.co.nz/page/prius-petrol-engine

Prius Power vs rpm

Small motor extends to 10,000 rpm.Small motor extends to 10,000 rpm.

One can see One can see why the why the electric electric motor is motor is

important important for power at for power at

all, all, but but especially especially lowlow, rpm., rpm.

Prius Power Train Performance

When Does The Engine Run?• To move the vehicle.• To charge the traction battery.• To warm up for lowest emissions.• To provide heat for passengers if needed.• To power the air-conditioner compressor if

needed.• To run hybrid-system diagnostics.• Prius misconceptions:

http://john1701a.com/prius/prius-misconceptions.htm

Smooth Acceleration

Regenerative BrakingECB = ECB = Electronically Electronically Controlled Braking SystemControlled Braking System which controls the which controls the coordination between coordination between friction braking and friction braking and regenerative braking, which regenerative braking, which preferentially uses preferentially uses regenerative braking. regenerative braking. Recovers up to 90%? of the Recovers up to 90%? of the possible recoverable possible recoverable energy down to 7 mph. energy down to 7 mph. Each wheel’s brake is Each wheel’s brake is independently controlled independently controlled electronically. Hydraulic electronically. Hydraulic backup brake control is on backup brake control is on the front wheels.the front wheels.

To “B” or not to “B”The The “B” selection“B” selection on the motion selector on the motion selector causes the engine to causes the engine to turn without firingturn without firing, using air compression and engine friction to , using air compression and engine friction to turn some of the vehicle’s motion energy into heat. Some of the turn some of the vehicle’s motion energy into heat. Some of the motion energy still goes into charging the battery, but not as motion energy still goes into charging the battery, but not as much as when “B” is not selected. (After using “B” you will need much as when “B” is not selected. (After using “B” you will need to reset the cruise control.) to reset the cruise control.) When might one use “B”?When might one use “B”?::

Be sure to move Be sure to move the motion the motion selector back to selector back to “D” after using “D” after using “B”, or you will “B”, or you will decrease the mpg decrease the mpg for normal driving.for normal driving.

When the battery is fully charged: When the battery is fully charged: all battery all battery bars are greenbars are green and you want to slow down. and you want to slow down.

When a sign says “When a sign says “Trucks use low gearTrucks use low gear”.”. When When going down a steep hillgoing down a steep hill and the cruise and the cruise

control cannot hold the car to less than 5 control cannot hold the car to less than 5 mph above the speed setting. mph above the speed setting.

B = engine braking.B = engine braking.

Constant Driving in B• Some owners of Prii drove all the time in B. I

know of two examples of this.• They complained that the mpg was low.• The reason is that the engine spins at high

rpm, without firing, going down hills and when braking, instead of turning off.

• It is an easy mistake to make, since the B position is straight down from the rest position of the movement selector. One has to move it to the left and then down for D.

Towing a Prius

• Do not leave the front wheels on the ground when towing if hybrid system is not on and in neutral. Doing so could damage the hybrid system.

• Towing hook for front is in cargo storage box; screw it into covered hole in front bumper.

• Best to use a flat-bed tow truck and raise the front wheels before pulling the Prius onto the truck.

• Two tie-down hooks are under the back, do not use them to tow the Prius from the back. Can be replaced by a tow bar for a bicycle rack.

• Do not allow towing or tie-down chain attachments to car frame; always use the front tow hook and the back tie-down hooks!

• If it must be towed with front wheels on ground, turn on hybrid system and put hybrid system in “N” and have someone guide it and work the brakes.

• Towing by Prius: should not be done! (Some have towed small trailers with a tow bar.)

Towing a Prius

Best way to put a Prius in Neutral to tow it with all wheels on the road:

• Press the power button twice without pressing the brake (IG ON mode).

• Put foot on brake and shift into Neutral. Hold the motion selector in Neutral for 3 seconds.

• Then it can be towed with the wheels on the road.

Prius as a Powerful Computer Network

• There are many Local Area Networks (LANs) connecting 5 computers in the vehicle. (All new vehicles have powerful computers and networks; hybrids take that one giant step further.)

• The LANs communicate through super networks. E.g., the climate-control network and the braking network communicate with the power-train network.

• For the keyless entry & start option, the vehicle’s main computer powers up using the 12-Volts battery when you approach the vehicle. When you press the Power button the other computers and LANs are turned on, powered by the 500-Volts traction battery.

• Pressing on the accelerator activates the motive networks according to the movement selection.

Prius as a Powerful ComputerECU = Electronic Control Unit = 32-bit computerECU = Electronic Control Unit = 32-bit computer

See See http://www.hybridcars.com/computer-control-systems.html and andhttp://techno-fandom.org/~hobbit/cars/bodyecuhttp://techno-fandom.org/~hobbit/cars/bodyecu

SOC = State of Charge of traction batterySOC = State of Charge of traction battery

What Happens When Your Press on the Accelerator?

1. The motive power demand from depression of the accelerator pedal (not the "throttle") goes to the Hybrid-ECU.

2. The Hybrid-ECU also gets power demand from the battery-ECU ("charge me" or "discharge me"), the air conditioner, etc.

3. The Hybrid-ECU decides where to get this power from, the ICE or the battery. If it wants power from the ICE, it sends a power demand to the Engine-ECU.

4. The Engine-ECU figures out how to get that much power from the ICE at the best efficiency and tells the Hybrid-ECU its choice of spin (torque) so that MG1 can be controlled appropriately.

5. The Hybrid-ECU controls MG2 to add or subtract power at the final drive as necessary.

6. Electrical power generated or consumed by MG1 and MG2 will result in a net surplus or deficiency that is provided or absorbed by the battery. In theory, this will correspond to the battery-ECU’s charge demand (see 2 above) but in practice there is much lee-way for things to come out differently and other power demands still to be met exactly. In a sense, the battery makes up the error.

15 Computers in a “Loaded” Prius1. HV ECU High Voltage ECU This is the brains of the HSD receiving and sending signals from all parts of the HSD turning driver request (shift, accelerator, break) into action by parts of the HSD system.

2. ECM Engine Module controls the ICE (spark, fuel injection, valve timing etc) delivering the proper amount of power to the system under direction of the HV ECU and informs HV ECU of ICE state.

3. Transmission ECU after receiving On signal from HV ECU monitors the Parking Switch (button) and when pressed it locks the hybrid trans axle and locks when brake is pressed and car is placed in D, R, N

4. Skid Control ECU Controls regenerative brake effect by MG2 and the hydraulic system to mimic a conventional hydraulic system as well as functions of Brake Assist, ABS (Antilock Brake System) and VSC (Vehicle Stability Control)

5. ECB ECU = Electronically Controlled Brake integrated into the Skid control ECU to calculate required brake force based on peddle effort and force.

6. EPS ECU = Electronic Power Steering ECU controls the power assist to steering column calculated from input from the Skid Control ECU and various sensors

7. Battery ECU monitors the SOC (State Of Charge) and battery temperature communicates with the HV ECU and controls the HV battery cooling fan.

8. Power Source Control ECU Controls the push button start system receives signals from switches and ECUs communicates to the HV ECU power on power off

9. Air Conditioning ECU calculates the compressor speed based on input from sensors using a nonlinear fuzzy logic system controls blower speed

10. Meter ECU Transmits vehicle speed signal, receives information if smart key is in vehicle and sound the warning sound in car on request of other ECUs (the source of the annoying beeps)

11. Body ECU receives door lock and unlock request and monitors if smart key is in vehicle transmits this to Smart ECU over a serial connection.

12. Transponder ECU Controls the HV immobilizer by recognizing the key ID code also works with Smart ECU in cars equipped with SKS. Transmits an HV stat authorization to the HV ECU

13. Smart ECU Checks ID code received from wireless transponders in the car and transmits the code to the Transponder ECU

14. Navigation ECU provides navigational features as well as Voice recognition and Bluetooth connection.

15. Gateway ECU provides communication between the 3 LANs (Local Area Network)

Prius Safe Computer “Hacks”• Turn off the backup beeper:

– Cycle ODO/TRIP, stopping on ODO.– Power off.– Power on, within 6 seconds, hold ODO for at least 10 seconds.– While still holding ODO shift into Reverse and back into Park.– "b-on" shows on display, press ODO to cycle to "b-off".

• Allow navigation destination parameters to be set while moving:– Press the "Menu" button (hardware button).– Press the "Voice" icon on the display.– Press the upper left corner of the display, where the speaker icon is.– Press the lower left corner.– Press the upper left corner again.– Press the lower left corner again.– The screen should change to a diagnostic screen.– Hold the "Override" button for several seconds until it changes to black

and a beep is heard.– Press the “Back” button.– This will be in effect only until the Power is turned off.– Warning: do not play with things on this screen that you don't know

about!

Prius Electric Safety• Battery is placed between the frame rails and in front of

the axle where it is least likely to be damaged in an accident.

• High-voltage cables are metal shielded, orange colored and placed away from possible damage in collisions.

• Battery power is cut off when an air bag deploys and other collision sensors activate.

• Vehicle does an electric system check when powered up.• Toyota provides special pamphlets for emergency

personnel: http://techinfo.toyota.com/public/main/2ndprius.pdf

• See http://www.asashop.org/autoinc/april2004/collision.cfm http://www.asashop.org/autoinc/aug2002/special.cfm

• See http://autos.groups.yahoo.com/group/toyota-prius/message/8834 for information about the difficulty of getting shocked by a Toyota Prius.

Prius Electric Safety

A ground-fault A ground-fault monitor keeps the monitor keeps the car frame from being car frame from being accidentally charged.accidentally charged.

Battery shut-off Battery shut-off relays.relays.

Fused safety plug: Fused safety plug: Pulling it out turns off Pulling it out turns off the high voltage.the high voltage.

Hybrid Reliability• Consumer Reports listed Toyota Prius and Honda Civic hybrid among the most

reliable vehicles for 2005 models.• Toyota Prius traction batteries regularly last for over 200,000 miles driving. Should

last 15 years.• The Toyota Synergy Hybrid System is much simpler mechanically than gasoline

vehicles (no transmission). The complexity is in the electronics, which is highly reliable.

• Engine does not always run, standard brakes are not always used for stopping and there is no starter or alternator to wear out. Brakes should last 100,000 miles.

• Early 2004-5 Toyota Prii had a software problem that caused the engine to stop. (EV still worked to move vehicle.) A software download fixed the problem after 68 known incidents of engine stalling. http://news.yahoo.com/s/ap/20051013/ap_on_bi_ge/prius_recall_1http://home.comcast.net/~bskattebol/50p.pdfhttp://www.earthtoys.com/emagazine.php?issue_number=05.08.01&article=naftc

• The modular design of the Toyota Prius allows defective modules to be quickly diagnosed and replaced.

• Prius Maintenance: http://john1701a.com/prius/prius-maintain04.htm

http://www.artsautomotive.com/Hybrid.htm• Car Talk Prius excellent review:

http://www.cartalk.com/content/testdrives/Reviews/toyota-prius-2004.htmlI have had one 2005 Prius recall to replace the steering column.

Prius I Engine Efficiency

http://techno-fandom.org/~hobbit/cars/prius-curves.gifhttp://techno-fandom.org/~hobbit/cars/prius-curves.gif

Peak efficiency is at about half power. The

“sweet spot”.

1500 rpm 2200 rpm 3000 rpm

Better to floorboard than to creep!Better to floorboard than to creep!

Worst efficiency is at low power.Worst efficiency is at low power.

http://john1701a.com/prius/presentations/prius_ths-presentation_07.htmhttp://john1701a.com/prius/presentations/prius_ths-presentation_07.htm

Differences in Driving a Prius• Power button starts the hybrid system, rather than a key. The

“key” fob must be somewhere in the car for “smart start” option; in the fob slot otherwise.

• Engine does not start immediately after system power is turned on; it starts about 7 seconds later to warm up the engine, then shuts off a few seconds later if not needed.

• Engine turns off at stops and when going down hills; also it does not provide power for backing up.

• Creep is built in at stops, provided by the electric motor. It is increased on an upward and downward slope to hold car in place. It can be turned off by pressing the brake pedal or putting the movement selector in the Neutral position.

• Slight sounds occur after stopping the car as hot coolant is pumped into the thermos container.

• Electric whine during slows starts and braking.• Special Brake position of movement selector to cause engine

braking.

How to Drive a Prius Efficiency• Use “Pulse Driving”:

– Accelerate rapidly at about half power, because a brief medium engine load uses less fuel than a prolonged low engine load. Best is when only the engine is moving the vehicle.

– Decelerate slowly well ahead of the stopping point to maximize brake regeneration. Best is when neither engine nor motor is moving the vehicle and the battery is not charging (gliding).

• Keep the vehicle in a garage during cold weather because a cold vehicle reduces brake regeneration.

• Keep tire pressure at recommended levels or higher to reduce tire friction losses. I up them by 2 psi.

• Steady 55 mph (55-60 mpg) is the point of peak efficiency. 75 mph: 40-45 mpg. For every mph faster than 55 mph, fuel economy drops by about 1 percent.

• http://home.earthlink.net/~graham1/MyToyotaPrius/Driving/Economy.htm

Driving for Lowest Emissions and Highest MPG

• MPG is much lower for the first 5-10 minutes of driving, because the engine is run until it reaches the best temperature for the lowest emissions. So, combine short-trips to save gasoline.

• MPG, as for all new cars, increases as the miles are driven up to about 10,000 miles.

• Higher tire pressure=higher MPG. Maximum pressure for the tires=44 psi. (Standard=35 front/33 back) Should be 2 psi greater in front than in back. I use 38/36; many use 42/40.

• Use cruise control when possible to get best MPG.

MPG versus MPH for 2003-8 Prius

Note the big decrease in mpg above 70 mph!Note the big decrease in mpg above 70 mph!