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Design of an Electromechanical Ratio and Clamping

Force Actuator for a Metal V-belt Type CVT

Koen van de Meerakker, Nick Rosielle,

Bram Bonsen, Tim Klaassen

Technische Universiteit Eindhoven

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Related sessions

Low level control of CVT’s 1 (4) Bram Bonsen

Low level control of CVT’s 2 (13) Tim Klaassen

(49) Bram

Veenhuizen

Theory in CVT applications (3) Bram Bonsen

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Belt CVT basics

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4

Variator actuation tasks

Sheave position -> Transmission ratio

Belt clamping force

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Typical CVT layout

Picture: Nissan Europe

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CVT driveline efficiency

With CVT, efficient IC engine use

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However:

Car with MT often more fuel-efficient

Power loss in CVT

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Power loss sources

Bearings, gears, seals

Torque converter

Variator efficiency

Hydraulic actuation

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Actuation power loss

Pump efficiency

Superfluous oil flow

Leak -> larger pump

Overclamping -> high oil pressure

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Variator actuation alternatives

Two stage pump

Electro-hydraulics

Electromechanical actuation

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EMconcept

M ratio

M clamp

Pri

Sec

Engine, TC

Wheels

Spindle

Spindle

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SpindlePulley shaft

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EMconcept

M ratio

M clamp

Pri

Sec

Engine, TC

Wheels

Spindle

Spindle

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Prototype approach

Modification of existing transmission

Actuators only in and on new outer

cover

Separate electric oil pump for

accessories

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Picture: Nissan Europe

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2222

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Features

Pri-sec mechanisms on same transmission side

Energy exchange pri-sec

Separate ratio and clamping force motors

No adjustment = no thrust bearing or el. motor

rotation

Electric motors outside transmission housing

Stiff in comparison to low pressure hydraulics

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Next

- Prototype assembly

- Assessment on test rig

- Assessment in Vehicle

-Redesign of research proto

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Picture: Audi AG

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Conclusions

Efficiency potential

EM actuation proposed

Prototype evaluation coming soon