Development of a Novel Parallel Hybrid Transmission

1. Development of a Novel Parallel Hybrid Transmission Lung-Wen Tsai Department of Mechanical Engineering University of California Riverside, CA 92521 (909) 787-2128 Lwtsai@engr.ucr.edu

2. Objectives • To improve vehicle fuel economy • To reduce hazardous emissions.

3. Background on Hybrid Electric Vehicles (HEVs) • DOE Initiatives • PNGV program • GATE program • Series Hybrid • Early times • Parallel Hybrid • New trend

4. Notable Hybrid Configurations • Toyota Prius (1998)

5. Toyota Hybrid System (THS) • 2-DOF (CVT) torque split device • Continuous mechanical and electrical paths from engine to output shaft • Uses 2 motor/generators • Single PG set

6. Notable Hybrid Configurations • Honda Insight (2000) • Integrated Motor Assist • Starter • Motor • Generator • Damper • MYBRID • 5-speed gearbox

7. Notable Hybrid Configurations • Chrysler • Dodge Durango (2003) • Electric front wheel drive & conventional rear wheel drive • Dodge Ram Contractor Special (2004) • Hybrid power train & auxiliary power generator • Ford Motor Co. • Escape SUV (2003) • General Motors • Epsilon platform SUV (2004) • MIBRID ParadiGM system

8. LWT Parallel Hybrid Transmission • Automatic transmission design with no torque converter • Operates as a 1-DOF or 2- DOF (CVT) mechanism • Sums torque • Splits torque • Uses only one electric motor/generator • 5 basic operational modes

9. Mechanism Description

10. Operational Modes

11. Motor Mode (1 DOF) • Used to initially move the vehicle from a standstill and for low speed driving in city traffic • “1st gear” equivalent

12. Engine 1 Mode (1 DOF) • Used during low speed, low torque cruising conditions • Lowest reduction • “2nd gear” equivalent

13. Power 1 Mode (1-DOF) • For low speed, high torque conditions • Power-assist compliment to E1

14. Engine 3 Mode (1-DOF) • Used during moderate speed, average torque conditions • 1:1 gear ratio (very efficient) • “3rd gear” or “direct drive” equivalent

15. Power 3 Mode (1-DOF) • For moderate speed, high torque conditions • 1:1 gear ratio (very efficient) • Power-assist compliment to E3

16. Engine 4 Mode (1-DOF) • Used during highway cruising conditions • “4th gear” or “overdrive” equivalent

17. CVT/Charge Mode (2-DOF) • Used to charge the batteries when battery state-of-charge is low and power requirement for cruising is low • Broad speed range

18. Power 2 Mode (2-DOF) • Broad speed range, low to moderate torque conditions • CVT operation

19. Kinematic and Static Analysis w1 + N41w4 – (1+N41)w3 = 0. (1) w1 + N31w3 – (1+N41)w2 = 0. (2) N41t1 + (N41/(1+N31))t2-t4 = 0. (3) (1 + N41)t1 + (1 + N41/(1 + N31))t2 + t3 = 0. (4)

20. Mode Shifting Analysis

21. Overdrive 2-DOF Charge 1-DOF Power & Charge 2-DOF Power E4 4th Vehicle Speed C V T 3rd P 2 E3 P3 2nd E1 P1 Stopped 1st Motor Notional Shifting Strategy

22. ADVISOR Model

23. Engine Efficiency Map

24. Motor Efficiency Map

25. Operating Limits – Hybrid Modes

26. ADVISOR Model Results Prius 52.0 mpg (city) Advisor Torque Assist 47.6 mpg (city) LWT400 50.6/59 mpg (city) • UDDS Preliminary Data

27. ADVISOR Model Results • UDDS Preliminary Data

28. Prototype Development • Based on GM THM-400 • Prototype complete • Preliminary testing started

29. Summary • A parallel hybrid transmission conceived with: • 1-DOF, 2 DOF (CVT), or combination capability • No torque converter • Only one motor/generator • Based on conventional automatic transmission components • Torque coupling and gear change transmission in a single embodiment • Well suited for hybrids requiring larger motor than MYBRIDS • Well suited for front-wheel drive applications • Can operate in engine-only modes during low lower cruising • Easily manufactured from existing automatic transmission tooling

30. Future Work • Testing prototype on the dynamometer • Continue control and shift strategy evolution • Integrate in a test vehicle • Patent pending • Seeking for support/collaboration Bourns College of Engineering