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
• [phone]
• Lwtsai_at_engr.ucr.edu

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Objectives

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

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Background on Hybrid Electric Vehicles (HEVs)

• DOE Initiatives
• PNGV program
• GATE program
• Series Hybrid
• Early times
• Parallel Hybrid
• New trend

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Notable Hybrid Configurations

• Toyota Prius (1998)

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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

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Notable Hybrid Configurations

• Honda Insight (2000)

• Integrated Motor Assist
• Starter
• Motor
• Generator
• Damper
• MYBRID
• 5-speed gearbox

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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

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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

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Mechanism Description
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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

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Engine 3 Mode (1-DOF)

• Used during moderate speed, average torque
  conditions
• 11 gear ratio (very efficient)
• 3rd gear or direct drive equivalent

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Power 3 Mode (1-DOF)

• For moderate speed, high torque conditions
• 11 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

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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

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Power 2 Mode (2-DOF)

• Broad speed range, low to moderate torque
  conditions
• CVT operation

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Kinematic and Static Analysis

• w1 N41w4 (1N41)w3 0. (1)
• w1 N31w3 (1N41)w2 0. (2)
• N41t1 (N41/(1N31))t2-t4 0. (3)
• (1 N41)t1 (1 N41/(1 N31))t2 t3 0. (4)

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Mode Shifting Analysis
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Notional Shifting Strategy
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ADVISOR Model
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Engine Efficiency Map
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Motor Efficiency Map
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Operating Limits Hybrid Modes
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ADVISOR Model Results
Prius 52.0 mpg (city) Advisor Torque Assist
47.6 mpg (city) LWT400 50.6/59 mpg (city)

• UDDS

Preliminary Data
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ADVISOR Model Results

• UDDS

Preliminary Data
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Prototype Development

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

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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

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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