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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.
Image courtesy of General Motors Corp.
Saturn CVT Transaxle
Image courtesy of General Motors Corp.
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
Image courtesy of General Motors Corp.
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
21
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
34
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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Dual Mode SystemDual Mode System
• 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
Image courtesy of General Motors Corp.
40
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
43
Four Hydraulic ClutchesFour Hydraulic ClutchesMultiple
DiscClutches
Image courtesy of General Motors Corp.
44
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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Compound Split ModeCompound Split Mode
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
49
Compound Split ModeCompound Split Mode
• 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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Dual Mode SystemDual Mode System
• 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
Image courtesy of General Motors Corp.
51
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
Image courtesy of General Motors Corp.
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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.
• The FWD Dual Mode transaxle is designed for small SUVs and full size cars powered by V6 engines.
Image courtesy of General Motors Corp.
• The FWD Dual Mode transaxle is designed for small SUVs and full size cars powered by V6 engines.
• 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
Image courtesy of General Motors Corp.
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End of PresentationEnd of Presentation