Industry News
MIRA debuts "Plugless Plug-In Hybrid" prototype
24th April 2008
MIRA (aka Motor Industry Research Association) has unveiled a retro-fit hybrid conversion with the potential to save 61% on a petrol vehicle’s fuel costs and lower tailpipe emissions by 39%. The ‘H4V’ hybrid conversion with a removable, 22Kg lithium-ion phosphate battery pack is shown in a technology demonstrator built around a Skoda Fabia with funding from the Energy Saving Trust's Low Carbon R&D programme.
Derek Charters, MIRA's Advanced Powertrain Manager says: "With this project we’ve removed the primary limitation of the “plug-in hybrid” concept by allowing the battery pack to come to the mains, rather than having to park right next to a socket ... which is more than a little difficult if you live in a terraced house or flat."
He explains further: "MIRA’s hybrid vision is to lower tailpipe emissions and deliver better fuel efficiency than an equivalent diesel, at a diesel-level on-cost.” (Of circa £2,000, assuming optimized production on a commercial scale.) MIRA plans to apply the lessons learned in the development of this concept demonstrator to other, more commercially-oriented hybrid projects which will lead to new hybrid models in the next year or two.
The 50/50 hybrid derives power jointly from the Fabia’s 60Kw petrol engine and two 35KW inboard motors powering the FWD car’s rear wheels though MIRA's ‘e-differential’. The control system provides for pure electric driving in the city, moving to series hybrid operation ‘in the suburbs’ and parallel hybrid operation in cruising conditions.
Overall, the H4V returns 64mpg, as measured on the EU drive cycle, a 61% improvement compared to the standard petrol model’s 39 mpg. Top speed and acceleration are similar to the standard petrol car’s. (The Skoda Fabia 70hp 1.4-litre diesel version does a combined cycle 58.9 mpg, while the 1.4-litre Fabia Greenline version achieves nearly 69 mpg, slightly more than the H4V prototype.)
The H4V’s battery pack is configured as three portable cassettes, each capable of storing 30KW. These storage units could also power external devices, which could include camping equipment, or to power electric jet skis or quad bikes. They take about 30 minutes to take a full charge, and can power the H4V in electric-only mode for up to about 15 miles. The pack's 22Kg weight is expected to reduce when readied for series production.
MIRA has applied nanotechnology to increase the energy density of the lithium ion phosphate batteries, which do not suffer the propensity to catch fire on impact of standard lithium-ion battery packs. The same li-ion phosphate battery technology is deployed in a separate low voltage circuit used to start the engine.
MIRA says headline-grabbing, ‘hyper-economic’ mpg figures were never the aim for H4V - to do that the team would logically select a more frugal base vehicle. The selection of the base car is largely unimportant, as far as the technology is concerned; so long as the donor vehicle's specification included modern features, such as a throttle by-wire system and some other basics, to avoid duplicating unnecessary workload. The project code of H4V, standing simply for ‘a' Hybrid 4wd Vehicle re-enforces the generic nature of the upgrade.
A 39% improvement is beyond what most traditional hybridisation systems would normally deliver, so MIRA have retuned the engine and created a custom calibration that works in harmony with the electrically driven axle to deliver additional synergies beyond the simple fuel savings possible via ‘torque-neutral' hybridisation schemes.
A regenerative braking system features on the MIRA hybrid, and is said to deliver enough energy recovery potential to outweigh its mass penalty. An aerodynamics pack reduces drag by 8% to achieve a Cd of 0.299.
MIRA is an automotive design, development & certification consultancy based in Nuneaton with over 400 staff supplying vehicle manufacturers, Tier 1 & 2 suppliers and other independent consultancies.
(www.mira.co.uk)
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