Torotrak V-Charge - Development of a Variable Drive Supercharger for OEM Application

The global automotive industry is under pressure to reduce C02 emissions, both from
legislation and consumer pressure. This is driving OEM’s to make vehicles more fuel efficient
with a variety of approaches such as reducing weight, improving aerodynamics and adopting
electric hybrid technologies.
Despite significant industry investment and incentives, hybrid electric vehicles are expected to
take a small percentage of total vehicles sales for the foreseeable future.
Internal combustion engine downsizing and downspeeding are expected to be the dominant
ways of reducing CO2 output, where a smaller engine with fewer cylinders running at lower
speeds, results in lower pumping and frictional losses which reduces fuel consumption.
Customers however are reluctant to trade bigger, more powerful engines for better fuel
economy. To regain lost performance, car makers are pressure charging these smaller engines
by a process of squeezing more air and fuel into the engine to increase its performance when
required.
The incumbent way of achieving this is by turbocharging which regains peak performance,
but on a downsized engine results in reduced driveability, and a phenomena referred to as
“turbo lag” may be experienced. This is when there is a delay between a driver pressing the
accelerator pedal and the vehicle accelerating, caused by the time it takes for the turbo to
generate boost.
The V-Charge variable drive mechanical supercharger remedies this situation by providing the
requested level of boost at any engine speed almost instantly, providing a driving experience
similar to a larger capacity naturally aspirated engine.
The key aims of the project are to assess the performance, fuel economy and emissions of a VCharge
equipped vehicle in a specific OEM application. Firstly in a modelling environment,
to produce a system specification to realise the full potential of the technology, and then in preproduction
prototype hardware on engine test bench and ultimately in vehicle.