Connaught develops "bolt-on" hybrid system
Connaught's "bolt-on" Hybrid+ system, the first application of which is in TESCO Ford Transit cargo vans, takes drive from the lower front pulley of the vehicle's engine.
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Small-scale UK auto manufacturer Connaught has developed an auxiliary mild-hybrid system, named Hybrid+, that is designed to be retrofitted to autos and light commercial vehicles. The first customer for the system is the home-delivery division of UK-based supermarket Tesco, which delivers groceries to customers at home. Seven Ford Transit refrigerated delivery vehicles will initially be equipped with the Hybrid+ system.
Connaught Chief Designer Geoff Matthews said that the system could be fitted to "any vehicle where there is sufficient space." He explained that the system uses a secondary, brushed, 48-V motor/alternator driven off the lower pulley drive on the front of the engine. "The unique bit is the constantly variable transmission (CVT) drive between the engine and motor/alternator. Even if the diesel engine is turning at 800 rpm, the CVT drive will ensure that the motor/alternator is spinning at its optimum 3000 rpm," he continued. The motor/alternator is sourced in the UK, while the CVT system is supplied from the U.S.
The vehicles are not equipped with an automatic engine stop/start system as with many hybrids because the engine must operate the refrigeration unit. The charge produced by the motor/alternator is stored in a Maxwell supercapacitor module about the same size as a heavy-duty 12-V battery. According to Matthews, the complete system, with supercapacitors, has a mass of about 50 kg (110 lb). He believes that this represents a considerable weight saving compared with a system using batteries. For the Tesco Ford Transits, the supercapacitor module is fitted beneath the load floor.
Matthews acknowledges that the vehicle's standard alternator could be removed when the Hybrid+ system is fitted, but Connaught has chosen to leave it in place for this application, "If the belt drive for the system were to fail, it would never disable the vehicle," he said.
The motor/alternator can provide an additional 15 bhp (11 kW) of power when the vehicle is accelerating. The supercapacitors feed the stored energy back to the motor/alternator, which then adds a degree of assistance to the engine via the belt drive. In the Tesco vehicles, the diesel engine retains the same power output as before, enabling them to call on the additional 15 bhp when needed. As Matthews pointed out, it would also be possible to reduce the power output of the diesel engine by 15 bhp to reduce fuel consumption and emissions.
On an urban delivery route, Matthews expects a reduction in fuel consumption and carbon dioxide emissions of between 15 and 20%—and possibly 25%—depending on the cycle, traffic conditions, and driver. Servicing of the Hybrid+ system is required every 30,000 mi (48,000 km), and the servicing is centered on the motor/alternator, which uses brushes that need to be inspected.
The cost of the Hybrid+ system would be around £2500, but would depend on the number of vehicles involved. "The system was designed and developed for high-volume vehicles," explained Matthews. "And this takes six months of design and development to tailor the system to a specific application."
The Connaught name was revived in 2002 by the current company. The original Connaught Engineering Company was a successful producer of Grand Prix and sports cars in the 1950s and early 1960s. The company's Type D hybrid sports coupe is scheduled to reach production later in 2007.
John Kendall
