1 transmissions for hybrid vehicles image courtesy of general motors corp. 2009 chevy tahoe

1Transmissions for Hybrid VehiclesTransmissions for Hybrid Vehicles

Image courtesy of General Motors Corp.2009 Chevy Tahoe

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Manual transmissions and HybridsManual transmissions and Hybrids

• To gain full advantage from regenerative braking the Insight driver needed to keep the clutch applied while slowing down so that the engine could be driven by the driveline while the IMA motor generated electricity

• This is contrary to the way that most drivers of manual transmission cars drive their vehicles – they apply the clutch and coast to a stop

• To gain full advantage from regenerative braking the Insight driver needed to keep the clutch applied while slowing down so that the engine could be driven by the driveline while the IMA motor generated electricity

• This is contrary to the way that most drivers of manual transmission cars drive their vehicles – they apply the clutch and coast to a stop

• The only hybrid vehicle sold in the US with a manual transmission was the 2000 Honda insight

• Manual transmissions do not work well with hybrids as they must remain in gear as the vehicle is slowing down

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Light and Mild HybridsLight and Mild Hybrids

• The electric motor/generator is connected to the engine crankshaft on a light or mild hybrid.

• This allows a conventional automatic transmission to be used.

• During regenerative braking driveline torque must be passed through the transmission, turning the crankshaft and allowing the motor / generator to generate electricity.

• During regenerative braking roller clutches that normally allow the transmission to freewheel must be locked out.

• The torque converter clutch must remain applied for the driveline torque to be transferred to the crankshaft.

• The electric motor/generator is connected to the engine crankshaft on a light or mild hybrid.

• This allows a conventional automatic transmission to be used.

• During regenerative braking driveline torque must be passed through the transmission, turning the crankshaft and allowing the motor / generator to generate electricity.

• During regenerative braking roller clutches that normally allow the transmission to freewheel must be locked out.

• The torque converter clutch must remain applied for the driveline torque to be transferred to the crankshaft.

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Light and Mild HybridsLight and Mild Hybrids

• In order for the motor/generator to receive torque from the driveline during regenerative braking the torque converter clutch and overrunning clutches must remained locked.

• To reduce engine drag and maximize regenerative braking some systems deactivate cylinders during braking.

• In order for the motor/generator to receive torque from the driveline during regenerative braking the torque converter clutch and overrunning clutches must remained locked.

• To reduce engine drag and maximize regenerative braking some systems deactivate cylinders during braking.

Motor/Generator

Torque ConverterClutch

OverrunningClutch

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Conventional Automatic transmissionsConventional Automatic transmissions

• The electrically driven hydraulic pump on this transaxle keeps hydraulic pressure applied to the clutches inside the transmission during engine stop mode

• The electrically driven hydraulic pump on this transaxle keeps hydraulic pressure applied to the clutches inside the transmission during engine stop mode

• A vehicle that has a start/stop function needs to be able to keep the transmission in gear and ready to accelerate the moment the gas pedal is depressed

• A vehicle that has a start/stop function needs to be able to keep the transmission in gear and ready to accelerate the moment the gas pedal is depressed

Electrically driven pump

Image courtesy of General Motors Corp.

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CVT TransmissionsCVT Transmissions• Continuously Variable

Transmissions are ideal for mild hybrid applications.

• CVT transmissions use metal belts and pulleys to transmit power through an infinite number of gear ratios.

• A CVT transmission allows the engine RPM to stay at a constant speed as the vehicle accelerates and decelerates.

• Continuously Variable Transmissions are ideal for mild hybrid applications.

• CVT transmissions use metal belts and pulleys to transmit power through an infinite number of gear ratios.

• A CVT transmission allows the engine RPM to stay at a constant speed as the vehicle accelerates and decelerates.


Saturn CVT Transaxle


7Mild Hybrid CVTMild Hybrid CVT

• Mild hybrids often use a mechanical CVT type transmission to optimize fuel economy

• Gear reduction is accomplished by a multi-link steel belt running between two pulleys

• The depth of the V-groove in the pulleys can be altered by changing the hydraulic pressure applied to one side of the pulley

• The only gears used inside the transaxle drive reverse gear or are used to transfer torque from the output pulley to the differential

• Mild hybrids often use a mechanical CVT type transmission to optimize fuel economy

• Gear reduction is accomplished by a multi-link steel belt running between two pulleys

• The depth of the V-groove in the pulleys can be altered by changing the hydraulic pressure applied to one side of the pulley

• The only gears used inside the transaxle drive reverse gear or are used to transfer torque from the output pulley to the differential


Output pulley

Input pulleyHydraulic

piston

Hydraulic piston

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Acceleration RPM / MPHAcceleration RPM / MPH

500

0 20 30 40 50 8060 90 100

7010

1000

1500

2000

2500

3000

3500

4000

ConventionalTransmission

CVT Transmission

Point where CVT transmission

reaches lowest overdrive

ratio

9CVT TransmissionCVT Transmission

• A CVT transmission uses a metal belt running between two adjustable pulleys to achieve an infinite number of gear ratios.

• A CVT transmission uses a metal belt running between two adjustable pulleys to achieve an infinite number of gear ratios.

Belt

Input Pulley

Output Pulley

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CVT PulleysCVT Pulleys

• Two cones combine to make a single pulley.

• The distance between the cones can be adjusted by a hydraulic cylinder.

• As the distance between the cones decreases the belt must ride further away from the center – effectively increasing the diameter of the pulley.

• Two cones combine to make a single pulley.

• The distance between the cones can be adjusted by a hydraulic cylinder.

• As the distance between the cones decreases the belt must ride further away from the center – effectively increasing the diameter of the pulley.

Moving ConeFixed Cone

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CVT PulleysCVT Pulleys

• To maintain belt tension the output pulley must mirror the change in the input pulley.

• When the spacing between the cones of the input pulley becomes smaller the spacing between the cones of the output pulley must become larger by the same amount.

• To maintain belt tension the output pulley must mirror the change in the input pulley.

• When the spacing between the cones of the input pulley becomes smaller the spacing between the cones of the output pulley must become larger by the same amount.

Input Pulley

Output Pulley

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Gear RatiosGear Ratios • When the input pulley is at

minimum diameter and the output pulley is at maximum diameter the transmission is at maximum reduction. Typically 2.5:1

• When the input pulley is at minimum diameter and the output pulley is at maximum diameter the transmission is at maximum reduction. Typically 2.5:1

• When the input pulley is at maximum diameter and the output pulley is at minimum diameter the transmission is at maximum Overdrive. Typically 0.4:1

MaxReduction

MaxOverdrive

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CVT Drive BeltCVT Drive Belt

• The belt is made up of hundreds of ‘T’ shaped links that a held together by two highly flexible steel bands.

• Unlike a rubber ‘V’ belt the metal belt transfers power by pushing through the belt – not by pulling.

• The belt is made up of hundreds of ‘T’ shaped links that a held together by two highly flexible steel bands.

• Unlike a rubber ‘V’ belt the metal belt transfers power by pushing through the belt – not by pulling.

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CVT Drive Belt and PulleysCVT Drive Belt and Pulleys

DriveBelt

InputPulley

OutputPulley

Forward/ReverseClutch

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CVT Pulley ActuatorCVT Pulley Actuator

• A hydraulic piston applies pressure to the moving cone.

• The piston is held inside the bore by spring tension.

• As the hydraulic pressure increases, the moving cone is forced into the fixed cone.

• A hydraulic piston applies pressure to the moving cone.

• The piston is held inside the bore by spring tension.

• As the hydraulic pressure increases, the moving cone is forced into the fixed cone. Hydraulic

PressureFeed

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CVT TransmissionsCVT Transmissions

• A CVT transmission changes ratios by adjusting the spacing between two cones that form the ‘V’ pulley.

• Moving the two cones together effectively increases the diameter that the belt contacts.

• Moving the cones apart effectively decreases the pulley diameter.

• A CVT transmission changes ratios by adjusting the spacing between two cones that form the ‘V’ pulley.

• Moving the two cones together effectively increases the diameter that the belt contacts.

• Moving the cones apart effectively decreases the pulley diameter.

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CVT TransmissionsCVT TransmissionsReverse Planetary

Flywheel

Output PulleyDrum

Input PulleyDrum

Belt

Starting Clutch

Valve BodyDifferential

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Starting ClutchStarting Clutch

• To get the car rolling from a dead stop the TCM applies a PWM duty cycle that lightly applies the clutch. Once the vehicle begins to move at a speed that will allow the engine to engage the driveline without stalling the clutch is fully engaged.

• To get the car rolling from a dead stop the TCM applies a PWM duty cycle that lightly applies the clutch. Once the vehicle begins to move at a speed that will allow the engine to engage the driveline without stalling the clutch is fully engaged.

Flywheel And Damper

Starting Clutch

TCM

Starting Clutch

Solenoid

• Honda hybrids do not use a torque converter.

• A multi-disc hydraulic clutch is used to couple and decouple the transmission form the final drive.

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Honda CVTHonda CVT

Flywheel

Damper

Input PulleyDrum

Output PulleyDrum

Belt

Starting Clutch

PressureRegulatorSolenoid

20Reverse Gear

Reverse Gear

• Reverse can be accomplished by two methods:

• Reverse can be accomplished by two methods:

Driving Gear

PlanetaryCarrier

Driven Gear

Idler Gear

Ring Gear

Sun Gear

Planetary gearset

Idler

Gearset

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Electronic CVTElectronic CVT

22Electronic CVTElectronic CVT

• The Electronic CVT transmission uses two electric motor/generators and a planetary gearset as a torque combining device

• The Electronic CVT transmission uses two electric motor/generators and a planetary gearset as a torque combining device

Motor/Generator #2Motor/Generator #1

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Two types of E-CVTTwo types of E-CVT

• Toyota Single Mode system used by:– Toyota/Lexus– Ford– Nissan

• Dual Mode hybrid system used by:– General Motors– BMW– Mercedes Benz– Chrysler

• Toyota Single Mode system used by:– Toyota/Lexus– Ford– Nissan

• Dual Mode hybrid system used by:– General Motors– BMW– Mercedes Benz– Chrysler

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SingleModeE-CVT

SingleModeE-CVT

• Toyota developed the single mode E-CVT for the original Prius.

• Toyota now licenses it’s hybrid system technology to Ford and Nissan

• Toyota developed the single mode E-CVT for the original Prius.

• Toyota now licenses it’s hybrid system technology to Ford and Nissan

2006 FordEscape Hybrid

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Torque Combining DeviceTorque Combining Device

• The single mode hybrid CVT uses a planetary gearset to combine torque from an ICE engine and two electric motor/generators.

• The single mode hybrid CVT uses a planetary gearset to combine torque from an ICE engine and two electric motor/generators.

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Planetary GearsetsPlanetary Gearsets

• The individual elements of the planetary gearset can be input, output or held.

• How the elements are driving, driven or held determines what gear ratio and direction of rotation is produced.

• The individual elements of the planetary gearset can be input, output or held.

• How the elements are driving, driven or held determines what gear ratio and direction of rotation is produced.

PlanetaryCarrier

Ring Gear

Sun Gear

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Single Mode TransmissionSingle Mode Transmission

• Ring gear– Connected to the final drive – Also connected to MG2– Rotates whenever the vehicle is in

motion

• Ring gear– Connected to the final drive – Also connected to MG2– Rotates whenever the vehicle is in

motion

PlanetaryCarrier

Ring Gear

Sun Gear

• Planetary carrier– Connected to the engine crankshaft – Rotates whenever the engine is running– Is effectively held whenever the engine is

not running

• Sun gear– Connected to MG1 – The sun gear and MG1 determine the

gear ratio and vehicle speed

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Single Mode Drive SystemSingle Mode Drive System

MG2 MG1

PlanetaryGearset

OilPump Transfer

Chain

FinalDrive

Damper

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Prius TransaxlePrius Transaxle

MG2

MG1

PlanetaryGearset

TransferChain

Damper

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www.eahart.com

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Operating ModesOperating Modes

ICE MG1 MG2

Reverse Off Freewheeling Forward

MotorMode

0 -25 MPH OFF Freewheeling Backwards

MotorMode

25 MPH Engine Start Starts HoldingMotorMode

25 – 65 MPH Cruise

RunningMotor Mode

GeneratorMode

Full Throttle Acceleration RunningMotor Mode

MotorMode

Deceleration Off Freewheeling Backwards

GeneratorMode

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Toyota Single Mode TransaxleToyota Single Mode Transaxle

MG2

DriveChain

PlanetaryGearset

Damper

MG1

OilPump

CoolantIn/Out

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Transmission & Inverter Cooling System

Transmission & Inverter Cooling System

Dedicated Radiatorfor Inverter

and Motor / Generator

ElectricWaterPump

Reservoir and Pressure Cap

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Transmission Cooling SystemTransmission Cooling System

• Note how the transaxle has 2 drain plugs.• Note how the transaxle has 2 drain plugs.

Drain for Inverter / Transaxle coolant

Drain for Transmission Fluid

2006 Highlander

Hybrid

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ControlsControls

• Range Selector knob electronically signals Hybrid Control Module for operating range.

• The ‘B’ range is used for engine braking on prolonged downhill driving.

• Range Selector knob electronically signals Hybrid Control Module for operating range.

• The ‘B’ range is used for engine braking on prolonged downhill driving.

• Park switch activates the park servo motor that engages the parking pawl in the transmission.

• There is no transmission control cable. All transmission controls are done electronically.

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Single Mode inefficiency at highway speedsSingle Mode inefficiency at highway speeds

• The single mode system is less efficient at highway speeds than a conventional transmission.

• At highway speeds MG2 generates electricity and MG1 uses that electricity to produce power.

• In this process about 20% of the overall energy produced by MG2 is lost to heat in the motors and inverter.

• The single mode system is less efficient at highway speeds than a conventional transmission.

• At highway speeds MG2 generates electricity and MG1 uses that electricity to produce power.

• In this process about 20% of the overall energy produced by MG2 is lost to heat in the motors and inverter.

Inverter

MG1MG2

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Dual Mode SystemDual Mode System

• The dual mode transmission combines the low speed efficiency of the single mode system with the high speed efficiency of a conventional mechanical planetary system.

• The dual mode transmission combines the low speed efficiency of the single mode system with the high speed efficiency of a conventional mechanical planetary system.

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• The dual mode system was a joint development project by engineers from:– General Motors– BMW– Mercedes Benz– Chrysler

• The first vehicle to use this system is the 2008 Chevy Tahoe & 2008 GMC Yukon.

• The basic system was developed in 1997 for GMC city busses – over 1000 of these are on the road.

• The dual mode system was a joint development project by engineers from:– General Motors– BMW– Mercedes Benz– Chrysler

• The first vehicle to use this system is the 2008 Chevy Tahoe & 2008 GMC Yukon.

• The basic system was developed in 1997 for GMC city busses – over 1000 of these are on the road.

39Dual Mode TransmissionDual Mode Transmission

• 3 Planetary Gearsets• 4 Multiple disc clutches

• 3 Planetary Gearsets• 4 Multiple disc clutches


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Dual Mode TransmissionDual Mode Transmission

• The Dual Mode transmission has a damper unit and does not use a torque converter.

• The damper drives an oil pump for high speed operation.

• An electrically driven oil pump is used for low speed operation.

• The Dual Mode transmission has a damper unit and does not use a torque converter.

• The damper drives an oil pump for high speed operation.

• An electrically driven oil pump is used for low speed operation.

Damper

ElectricOil Pump

MechanicalOil Pump

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MG2MG1

OutputPlanetaryGearset

InputPlanetaryGearset

Damper

Dual Mode Transmission componentsDual Mode Transmission components

• Two 60 KW [80 HP] electric motor / generators provide power for low speed electrical operation.

• Two 60 KW [80 HP] electric motor / generators provide power for low speed electrical operation.

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Three Planetary GearsetsThree Planetary Gearsets

• The two electric motors are connected to elements of the front and center planetary gearsets

• The two electric motors are connected to elements of the front and center planetary gearsets

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Four Hydraulic ClutchesFour Hydraulic ClutchesMultiple

DiscClutches


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Dual Mode ComponentsDual Mode Components

Input Planetary

ReactionPlanetary

OutputPlanetary

MG1 MG2

DrivingClutch A

HoldingClutch B

DrivingClutch C

HoldingClutch D

Damper

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Input Split ModeInput Split Mode

• Input split mode functions just like the single mode of the Toyota System

• The two electric motors provide torque for low speed operation and the power of the ICE engine can be combined with the two motors to provide maximum torque for acceleration.

• Hydraulic clutch ‘D’ [ 2nd gear] is needed to connect the two front planetaries to the output shaft.

• Input split mode functions just like the single mode of the Toyota System

• The two electric motors provide torque for low speed operation and the power of the ICE engine can be combined with the two motors to provide maximum torque for acceleration.

• Hydraulic clutch ‘D’ [ 2nd gear] is needed to connect the two front planetaries to the output shaft.

Clutch DApplied

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Input Split ModeInput Split Mode

• In Input-Split mode the vehicle can operate under electric power or a combination of electric power and ICE power.

• Under electric operation MG1 acts as a generator and MG2 acts as a motor.

• Input-split mode uses 1st and 2nd gear fixed gear ranges.

• The Input-Split mode usually functions at speeds between 0 and 30 MPH.

• In Input-Split mode the vehicle can operate under electric power or a combination of electric power and ICE power.

• Under electric operation MG1 acts as a generator and MG2 acts as a motor.

• Input-split mode uses 1st and 2nd gear fixed gear ranges.

• The Input-Split mode usually functions at speeds between 0 and 30 MPH.

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Compound Split ModeCompound Split Mode

• Compound-Split mode provides 4 fixed gear ratios using multiple disc clutches and planetary gearsets.

• Power from the engine is delivered directly to the four multiple disc clutches and two rear planetary gearsets.

• Compound-Split mode provides 4 fixed gear ratios using multiple disc clutches and planetary gearsets.

• Power from the engine is delivered directly to the four multiple disc clutches and two rear planetary gearsets.

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A B C D

Clutch ‘A’ Clutch ‘B’ Clutch ‘C’ Clutch ‘D’

First Gear On Off Off On

Second Gear Off Off On Off

Third Gear On Off On Off

Fourth Gear Off On On Off

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• Compound-Split mode provides greater efficiency than Input-split mode at highway speeds.

• When running in the Compound-Split mode the electric motors can kick-in whenever additional torque is required.

• Compound-Split mode usually begins at about 30 MPH.

• When the vehicle is running in compound split mode the electric motors can be turned off.

• Compound-Split mode provides greater efficiency than Input-split mode at highway speeds.

• When running in the Compound-Split mode the electric motors can kick-in whenever additional torque is required.

• Compound-Split mode usually begins at about 30 MPH.

• When the vehicle is running in compound split mode the electric motors can be turned off.

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• The Duel Mode electrical system is essentially the same as the single mode system.

• Since the Dual Mode system is more efficient a simple transmission cooler is sufficient for removal of excess heat from the electric motors.

• The Duel Mode electrical system is essentially the same as the single mode system.

• Since the Dual Mode system is more efficient a simple transmission cooler is sufficient for removal of excess heat from the electric motors.

Inverter

300 volt Ni-MH Battery

pack

Dual Mode Transmission

12 volt Battery


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Additional Fuel Saving TechnologyAdditional Fuel Saving Technology

• The Dual Mode system also uses:

– Adaptive Fuel Management• 2 or 4 Cylinders are turned of during cruise• Active pulsation dampening is used to reduce

vibration

– Late Intake valve closing• Atkinson cycle

• The Dual Mode system also uses:

– Adaptive Fuel Management• 2 or 4 Cylinders are turned of during cruise• Active pulsation dampening is used to reduce

vibration

– Late Intake valve closing• Atkinson cycle

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Dual Mode System for Front Wheel DriveDual Mode System for Front Wheel Drive• Just before the GM bankruptcy GM

introduced a front wheel drive version of the Dual Mode system using a 3.6 liter V6

• Just before the GM bankruptcy GM introduced a front wheel drive version of the Dual Mode system using a 3.6 liter V6

• The transaxle for the Vue was adopted for use in the Chevy Volt plug in hybrid


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Dual Mode System for Front Wheel Drive

Dual Mode System for Front Wheel Drive

• The FWD Dual Mode transaxle is designed for small SUVs and full size cars powered by V6 engines.





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GM 2009 Hybrid FWD PowertrainGM 2009 Hybrid FWD Powertrain

• This powertrain was used brifely in the 2009 on the:

– Chevy Malibu Hybrid– Saturn Aura Hybrid

• This powertrain was used brifely in the 2009 on the:

– Chevy Malibu Hybrid– Saturn Aura Hybrid

3.6 liter V-6 ICE engine with direct injection

330 Volt Ni-MHbattery array

12 Volt auxiliary battery

Dual Mode Transaxle


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End of PresentationEnd of Presentation

1 transmissions for hybrid vehicles image courtesy of general motors corp. 2009 chevy tahoe

Documents

engine crankshaft

overrunning clutches

mild hybrids

electric motorgenerator

motor generator

driven pump

insight driver

chevy tahoe slide