Torotrak Group Flywheel energy storage as a key part of future powertrains

Jon Hilton FIMechE CEng

Product Development and Sales Director Torotrak Group

Preliminary Results Announcement – 2013/14 28 May 2014

2 Torotrak product portfolio

Preliminary Results Announcement – 2013/14 28 May 2014

3

Make engines smaller

Engine downsizing

1 Transmissions

Optimising energy efficiency

2 Recover energy

Hybridisation

Infinitely Variable Transmissions

Variable Supercharging

Mechanical Kinetic Energy Recovery

3 Flybrid technology: core components

Flybrid Clutched Flywheel

Transmission

Energy storage

Flybrid High Speed Flywheel

Energy transmission

4 Bus and Truck • A ‘Parallel Hybrid’ energy recovery system

• A cost effective, low risk route to:

– Fuel Economy improvement and/or enhanced performance – CO2 & particulate emissions reduction

• Applications include: – City buses – Rural buses – Delivery trucks – Refuse collection

• First customer: Wrightbus

5 Commercial Vehicle KERS Flywheel KERS 600kJ / 120kW

Bus Gearbox

Bus Rear Axle KERS Torque at Rear Axle = 5,000Nm

Transfer Gearbox 1:1 Ratio

Power Take Off 1.8:1 Ratio

1,000,000km Life requirement

⇒ >42,000h of service

⇒ >8million storage + release cycles

9 Powertrain Considerations The opportunity to store energy on board the vehicle can transform how the whole powertrain works Until now most work in this area has been concentrated on battery electric solutions and these have particular characteristics in relation to power capability and storage capability • Power and storage capacity are related • A range of batteries are available with different power to storage ratios • The most work has been done on large storage applications at modest

power levels

But the requirement for kinetic energy storage in cars, buses and trucks is high power and small quantities of storage

10 Powertrain Considerations

11 Powertrain Considerations

Flybrid® Road Car – 3,300 W/kg, 8.3 Wh/kg

Flybrid® Commercial Vehicles – 4,000 W/kg, 6 Wh/kg

4,000

12 Powertrain Considerations There are significant opportunities for integration of the KERS with the vehicle gearbox rather than using the parallel architecture shown for the bus

• Connecting the system to a shaft with a higher speed reduces the number of gears required in the KERS unit saving size, weight and cost

• Connecting the system to a shaft with a narrower speed range than the wheels reduces the number of gears / clutches required in the KERS unit with big benefits to size, weight and cost

It is possible to connect the KERS to the layshaft of a manual gearbox and several of the Flybrid racing projects have been done this way

• With this configuration it is possible to perform additional functions like engine start / stop using the flywheel and flywheel charging straight from the engine at high efficiency

• The KERS must be switched off during gearshifts • The Flybrid® KERS can be switched off in under 10 ms and back

on in under 15 ms

Preliminary Results Announcement – 2013/14 28 May 2014

Flybrid KERS Integration into manual gearbox 13

14 Future Direction At Torotrak we want cars to be fun, which for us means fast acceleration. We also want them to be excellent on fuel and emissions, which means low losses when cruising at constant speed, low weight and minimum wastage of energy We believe that this can be achieved by separating the power required for acceleration from the power required for cruising at constant speed. These vehicles will power their ‘hotel leads’ (the low power electrical requirement to power auxiliaries, ECU, headlights, etc.) using electricity generated by a small electric generator integrated with the KERS and store this in a low voltage battery. This requirement will use about 10% of the available kinetic energy. A flywheel KERS will be used for load levelling and to achieve the desired acceleration performance

Preliminary Results Announcement – 2013/14 28 May 2014

Future Direction 15

NEDC < 70gCO2/km

AND

0-60 in <8 seconds

Extreme downsized ICE Or

Battery Electric Or

Fuel cell

100kW Flywheel Hybrid 30kW Prime Mover

Acceleration peaks

average power requirement

16 Deletion of foundation brakes With this solution we can consider deletion of foundation brakes on the driven axle • 100 kW produces a lot of braking effort in normal use • For short durations much more than 100 kW can be stored • The flywheel needs to have a big enough energy capacity to accelerate to

80 MPH so it will have 30% spare capacity when coming back down from 80 MPH (assuming 70% round trip efficiency)

• Any excess of energy, such as generated when braking down a long hill, can be trimmed off by a number of methods • Re-engaging the engine on overrun (in any chosen gear) • Slipping two CFT clutches (two gear ratios) against each other • Deliberately putting up system parasitic losses

• The vehicle can also be brought fully to rest and held there by slipping two CFT clutches against each other and then holding them shut

17 Deletion of foundation brakes We might consider a vehicle with full KERS braking on both axles whereupon the conventional brake pedal can be considered redundant • KERS braking is obviously fully brake by wire • Brakes are only operated by a foot pedal because the leg is stronger than

the hand and this additional pressure was needed • Packaging space is tight around the foot well, especially allowing for left

and right hand drive variants • Crash performance might be improved by no brake pedal

• We might consider a ‘one pedal’ car where a single control provided both

throttle and brake functionality • We have probably all driven one of these – A Dodgem • It would take a short time to get used to but has many safety benefits

including a ‘dead mans handle’ functionality

18 The future of powertrain engineering With the expected popularity of KERS functionality we can expect a range of new challenges for powertrain engineers Vehicles are not going to get slower or less powerful just because they emit less CO2 Ultimately Torotrak expects all of the energy of the vehicle braking system to be captured by the KERS and that this will be divided between energy that is returned directly to the wheels by the flywheel and that which is used to run the vehicle ‘hotel loads’ electrically The vehicle powertrain is expected to get more complicated and more expensive whilst braking systems are expected to get less powerful, ultimately tending to deletion

Contact: Jon Hilton Email: Jon.Hilton@torotrak.com Tel: +44 (0) 1772 900 900