Transmission Systems for Hybrids

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new MPS6 Powershift transmission with a 3-shaft design for I4 and V6 in C- and CD- cars and on the other hand the SPS6 Powershift transmission with an ...
Transmission Systems for Hybrids

Summary

Powershift - New Transmission Technologies Today’s car industry is requesting higher performance from transmission technologies in terms of efficiency, speed, torque and flexibility in launch and shift characteristics. The newly developed double-clutch transmissions from GETRAG FORD Transmissions combine the advantages of conventional six-speed manual-shift gearbox with the qualities of a modern automatic transmission. Two variants with a torque range up to 450 Nm are explained, on the one hand the new MPS6 Powershift transmission with a 3-shaft design for I4 and V6 in C- and CDcars and on the other hand the SPS6 Powershift transmission with an extremely short 2x2 shaft design for I5 and I6 in CD-car and SUVs. The design of such Powershift transmissions, which provides excellent acceleration without any interruption of powerflow, is shown and the technologies to meet customers’ requirements of immense agility and driving pleasure are explained. The modular design and manufacturing principles demonstrate cost and resource orientated production: design highlights like the hydraulic gear change and clutch actuation, the integrated TCU, the parallel wet clutch and 3-chamber oil management demonstrate newest product technologies:



The benefits of the hydraulic concept are a commonized and compact main control, reduced number of cost-intensive variable force solenoids and good

controllability during shifting, excellent clutch controllability, improved thermal stability for creep & hill hold with improved cold shiftability. •

An integrated control unit for double-clutch transmission guarantees gear shifting in milliseconds, with a silky-smooth shifting without jerks or interruption of tractive force.



The benefits of parallel wet clutch design are excellent controllability and robustness due to fully centrifugal compensation on both clutches, equal gains on both clutches and separate lube/cooling for both clutches.

State-of-the art control software architecture with an automatic shift strategy for drive situation detection and shift scheduling and a drive line manager who coordinates all modules required for changing gears complete the design walk of the Powershift transmissions Detailed efficiency measurements for gasoline and diesel applications underline the remarkable improvements in fuel consumption.

Hybrid Extension of Powershift Technology Hybrids have to be seen on a technology migration path for transmissions. State of the art automatic transmissions will be enhanced to hybrid aggregates, thus providing the entry ticket in electric driving era. The key drivers for hybrids are changing environmental conditions, constraints in oil supply, high oil prices and the need for technological differentiation among OEM’s. For Hybrid to become a commercial success it is important to find sound business cases like in commercial vehicles with electric range or extremely fuel saving passenger cars. GETRAG FORD Transmissions looks upon its system as a 2nd generation Hybrid based upon dual clutch transmission technology and the use of two electric machines sized 15-25 kw. This system enables parallel and serial hybrid operation. The size of the electric motors does not need adaptation to combustion engine size due to the parallel hybrid

concept as opposed to an E-CVT. The system allows engine downsizing through massive boosting, regenerative braking, start stop, hill hold and electrical reverse in serial hybrid mode without battery storage constraints. Dual clutch transmission functionality is uncompromised. The project is currently in the early prototyping phase. In a comparison of operating modes of hybrid electric powershift (HEPS) and a powersplit hybrid layout which is in production is it particularly evident that Powershift based hybrid technology has significant advantages in steady state long distance driving compared to powersplit technology, which makes HEPS an excellent solution for North American and European customer usage.

4th International CTI-Symposium Innovative Automotive Transmissions 4. Internationales CTI Symposium Innovative Fahrzeug-Getriebe 5 to 8 December 2005, Berlin, Germany

Transmission Systems for Hybrids

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Rolf Najork, GETRAG FORD Transmissions

06/07-Dec-2005 / Rolf Najork - CTI Berlin

Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 2

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Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 3

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Drivers for Hybrid Expansion •

Security of oil supply - political instability in Arab World and shrinking oil reserves will drive fuel efficient vehicles



Increasing emission restriction - further challenges for diesels, reducing the cost gap between Hybrids and Diesels



Competitive pressure - OEMs setting the pace in environmentally friendly products and market them well



Technology shift - Hybrids provide entry in electric driving era, creating the basis for fuel cell technology



Western OEM’s need next-generation vehicles to maintain competitive advantage low cost competition from emerging markets

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 4

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Market Projection on Hybrid Sales 3M Projection 2015 Actual 2004

1M 83000 USA

60000 Japan

1M 12000 Europe

The projection is based on a publication by Prof. Dudenhoeffer

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 5

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Business Case Scenarios for Hybrids We need to define market niches for Hybrids to design systems that meet customer needs and can be sold profitably • Performance hybrid vehicles diesel and gasoline for Europe and US without trailer towing restrictions (significant advantage over conventional diesel powertrains required) • Quiet and zero-emission passenger cars that can access areas which are not permitted for conventional cars (taxi driving, pedestrian zones, holiday resorts, private customers with focus on environment) • Light Trucks for special delivery zones (pedestrian zones, hotels, hospitals) • Commercial Vehicles which need power supply 220V/2000W for business purpose, camping and outdoor occasions

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 6

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Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 7

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GFT Hybrid Requirements •

Torque split instead of power split



Parallel and serial hybrid operation



Power transferred mainly through mechanical path



Wide range of ratios and speeds within gearbox (reduced size of electrical motors, mechanical fallback layer)



Significantly reduced need for battery capacity (cost and weight impact)



Deliver economy far superior to classic diesel powertrains



Capability for mild and full hybrid functionality

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 8

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Powershift Concept HEPS / SHEPS • Dual clutch base transmission • 2 electric motors (scaleable for power and battery size) • Electric motor power 15 and 25 kW (total 40 kW) • Gearbox integrated design for package and installation benefits • Start/Stop at standstill and during drive (electric coasting, full electric drive – depending on energy storage size) • Recuperative breaking / electric boosting • Hill hold, launch and reverse electrically assisted

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 9

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Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 10

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MPS6/SPS6 Concept MPS6 (3 shafts)

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 11

SPS6 (2x2 shafts)

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Extension Hybrid MPS6 Base

Mild Hybrid

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Full Hybrid

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Extension Hybrid SPS6 Base

Mild Hybrid

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Full Hybrid

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Packaging of Electric Motors

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GFT Full Hybrid Powershift Concept HEPS* • Based on XPS lay shaft transmission architecture (parallel clutch) • Two electric motors acting on input shafts Configuration allows for a multitude of working modes (serial & parallel) EM 1

Current SPS6

1,3,5 ICE

FD 2,4,6 EM 2

* Patents pending (Torque split vs conventional Power split approach) 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 15

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GFT Short Hybrid Powershift Concept SHEPS* • Based on XPS lay shaft transmission architecture (parallel clutch) • Two electric motors, one connected to crankshaft, one connected to input shaft Configuration allows for a multitude of working modes (serial & parallel) EM 1

Current SPS6

1,3,5 ICE

FD 2,4,6 EM 2

* Patents pending (Torque split vs conventional Power split approach) 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 16

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Overview • • • • • •

Business Environment SHEPS /HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 17

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Comparison of different driving modes (1) HEPS versus Power-Split

Engine start at standstill HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Insensitive to EM control (no talk-through of variations) • Both EMs available (cold start)

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 18

B

EM 2

• Sensitive to EM control (variations feel able in vehicle) • Only one EM available (other EM needed to counteract start torque) Together for Success

Comparison of different driving modes (2) HEPS versus Power-Split

Launch with engine running HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Normal launch without any EMs possible • Boosting during launch with both EMs possible • Launch torque limited by transmission torque only 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 19

B

EM 2

• One EM works as generator, one EM works as booster • ICE launch torque limited by EM (generator) size

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Comparison of different driving modes (3) HEPS versus Power-Split

Creep or Reverse HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Boosting during launch with both EMs possible • Normal launch without any EMs possible • Launch torque limited by transmission torque only 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 20

B

EM 2

• One EM works as generator, one EM works as booster • Electrical IVT

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Comparison of different driving modes (4) HEPS versus Power-Split

Normal driving (complete range) HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Pure mechanical drive (high efficiency) • Boosting with both EMs possible (depending on battery capacity) • Recuperative braking with one or two EMs • 6 speed transmission with powershift • ICE power independent of EM power 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 21

B

EM 2

• Up to 1/3 of the energy transferred electrically • One EM works as generator, one EM works as booster • Drives as CVT • Maximal ICE power depending on maximal EM power Together for Success

Comparison of different driving modes (5) HEPS versus Power-Split

Normal driving (specific speed range) HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Pure mechanical drive (high efficiency) • Boosting with both EMs possible (depending on battery capacity) • Recuperative braking with one or two EMs • 6 speed transmission with powershift • ICE power independent of EM power 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 22

B

EM 2

• Lock-up clutch engaged • Boosting with one EM possible (depending on battery capacity) • Drives with designed ratio (high efficiency) Together for Success

Comparison of different driving modes (6) HEPS versus Power-Split

Electric drive HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Electric drive with one or two EMs possible • Torque can be multiplied by ratio

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 23

B

EM 2

• Electric Drive in base configuration only with EM2 • If ICE is braked by sprag clutch, electric drive with both EMs possible • Torque limited due to constant ratio Together for Success

Comparison of different driving modes (7) HEPS versus Power-Split

Start/Stop HEPS

Power split type

EM 1 EM 1 1,3,5 ICE

FD

ICE

P/S

FD

2,4,6

B

EM 2

• Launch during engine start possible • After engine start, boosting with two EMs possible

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 24

B

EM 2

• Start/Stop implemented by control of EM1 • Quality of Start/Stop is depending on control strategy Together for Success

Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 25

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Simulation Model for Fuel Economy Investigations

• Matlab Simulink based simulation • Detailed complete vehicle model with major parasitic losses • Engine, transmission, auxiliary drives maps included 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 26

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NEDC Fuel Economy Simulations (Hybrid Drive Strategy vs ICE Mode)

Speed [km/h] ICE base torque [Nm] ICE Hybrid torque [Nm] EM1 torque [Nm] EM2 torque [Nm]

Speed [km/h] ICE base torque [Nm] ICE Hybrid torque [Nm] EM1 torque [Nm] EM2 torque [Nm]

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 27

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Performance and Fuel Efficiency (Assumption Equal 0-100 Performance)

Gasoline, 400Nm Gasoline, 320Nm Gasoline, 320Nm+2*EM

Equal 0-100 acceleration

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 28

Gasoline, 400Nm Gasoline, 320Nm Gasoline, 320Nm+2*EM

Pure electric drive

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Drive Modes During City Driving Efficiency Optimized Driving

= ICE running, EMs used as generators charging battery = ICE off, electric coasting with one EM, battery discharging = ICE off, recup breaking with one or two EM, charging battery = All off during idle 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 29

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Drive Modes During City Driving Emissions Optimized Driving

= ICE on, boosting with EMs, battery discharging = ICE on or off, charging battery with EMs or electric coasting = ICE off, recup breaking with one or two EM, charging battery = All off during idle 06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 30

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Simulation Roadmap in NEDC Base: SUV, Gasoline 400Nm, torque converter automatic transmission Hybrid: SUV, Gasoline 320Nm, DCT based (2*20kW, 150kg additional weight) Software complexity 1

2

3

4

Mild Hybrid with ISG. Fuel consumption change (EC00) Performance change (0-100 km/h)

1 -5%

2

Full Hybrid 2x20KW Rule based strategy. No Battery SoC)

Hardware Complexity

-24%

3

+1%

-9%

Full Hybrid , ext. rule based strategy modified gearbox enhanced batt -25%

-1%

Full Hybrid 2x20KW.Rule based strategy. SoC feedback -21%

-9%

Full Hybrid Ext. rule based strategy incl SoC feedb. enh.batt. Mod gear. -30%

-1%

Full Hybrid 2x20KW. Rule based strategy. SoC feedback, Gear shift control. -28%

-1%

Full Hybrid Ext. rule based Strategy SoC feedb. Gearshift Ctrl enh. batt mod gear

-32%

-1%

Full Hybrid 2x20KW Evolutionary algorithm for optimal solution (time ind.) -36%

NA

Full Hybrid Evolutionary algorithm for optimal,enh. Batt. mod. Gear. -33%

NA

F/E Opportunities: •DCT: 5% (incl. weight handicap) •Downsizing: 5% •Base hybridization (Start/Stop, Boosting, Recuperative braking, low speed E-Drive): 15% •Enhanced hybridization (special DCT modes, evolutionary algorithms, GPS): up to 11%

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 31

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Overview • • • • • •

Business Environment SHEPS/HEPS Concept Powershift Base Transmission Operating Strategy Projected Fuel Economy Savings Conclusion

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 32

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Conclusion •

DCT technology provides an excellent basis for Hybrid



Torque split with multiple gears instead of power split improves steady state fuel economy



Reduced size of electric motors, power electronics and battery



Hybrid transmission electric motor power widely independent from combustion engine power



Mild hybrid and full hybrid option



Parallel and serial mode operation



Significant fuel economy improvements

06/07-Dec-2005 / Rolf Najork - CTI Berlin / page 33

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