Development of a Novel Parallel Hybrid Transmission Lung-Wen Tsai Department of Mechanical Engineering University of California Riverside, CA (909)

Objectives To improve vehicle fuel economy To reduce hazardous emissions.

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

Toyota Prius (1998) Notable Hybrid Configurations

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

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

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

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 LWT Parallel Hybrid Transmission

Mechanism Description

Operational Modes

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

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

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

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

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

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

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

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

Kinematic and Static Analysis  1 + N 41  4 – (1+N 41 )  3 = 0.(1)  1 + N 31  3 – (1+N 41 )  2 = 0.(2) N 41  1 + (N 41 /(1+N 31 ))  2 -  4 = 0.(3) (1 + N 41 )  1 + (1 + N 41 /(1 + N 31 ))  2 +  3 = 0.(4)

Mode Shifting Analysis

Notional Shifting Strategy E3 E1 E4 Motor P2P2 P3 P1 CVTCVT Vehicle Speed Stopped Overdrive 2-DOF Charge 2-DOF Power 1-DOF Power & Charge 1st 2nd 3rd 4th

ADVISOR Model

Engine Efficiency Map

Motor Efficiency Map

Operating Limits – Hybrid Modes

ADVISOR Model Results UDDS Prius52.0 mpg (city) Advisor Torque Assist 47.6 mpg (city) LWT /59 mpg (city) Preliminary Data

ADVISOR Model Results UDDS Preliminary Data

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

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 Summary

Testing prototype on the dynamometer Continue control and shift strategy evolution Integrate in a test vehicle Patent pending Seeking for support/collaboration Future Work