|The H4V on the test track.|
MIRA (Motor Industry Research Association), a UK-based automotive design, development and certification consultancy, has unveiled a plug-in hybrid retrofit system with the potential to reduce fuel consumption and tailpipe emissions by 39%, and applied it in a demonstrator vehicle.
The ‘H4V’ (Hybrid 4 wheel drive Vehicle) features a novel removable lithium-ion phosphate battery pack. MIRA built the technology demonstrator around a Skoda Fabia with funding from the Energy Saving Trust’s Low Carbon R&D program.
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.—Derek Charters, MIRA’s Advanced Powertrain Manager
The hybrid derives power jointly from the Fabia’s 60 kW (80 hp) gasoline engine and two 35 kW inboard motors powering the front-wheel drive 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.
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.
Overall, the H4V returns 4.4 L/100km (64 mpg UK, 53 mpg US), as measured on the EU drive cycle, a 39% reduction compared to the standard gasoline model’s 7.24 L/100km. Top speed and acceleration are similar to the standard gasoline model. The Skoda Fabia 70hp 1.4-liter diesel version does a combined cycle 4.8 L/100km, while the 1.4-liter Fabia Greenline version achieves nearly 4.1 L/100km, better than the H4V prototype.
|The removable cassettes. Click to enlarge.|
The H4V’s battery pack is built from portable cassettes, each with 1.5 kWh capacity. MIRA designed and made the battery packs, using Li-Ion Phosphate cells “sourced from an American supplier.” They take about 30 minutes to take a full charge, and in combination can power the H4V in electric-only mode for up to about 15 miles. The pack’s 22 kg weight (for a double cassette pack) is expected to reduce when readied for series production.
The battery units could also power external devices, which could include camping equipment, or to power electric jet skis or quad bikes.
MIRA 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' hybridization schemes.
The MIRA hybrid uses regenerative braking, which can deliver enough energy recovery potential to outweigh its mass penalty. An aerodynamics pack reduces drag by 8% to achieve a Cd of 0.299.