Machine Design
Jaguar’s high-power hybrid concept car harnesses a pair of micro gas turbines

Jaguar’s high-power hybrid concept car harnesses a pair of micro gas turbines

Jaguar Cars Ltd.,

Engineers at Jaguar Cars Ltd. took a truly innovative approach when designing the C-X75 concept car. The two-seater’s hybrid drive uses a 145-kW (195-hp) hub motor on each wheel, giving the car four-wheel drive. A floor-mounted lithium-ion battery pack delivers 19.6 kW-hr. But most noteworthy is the pair of micro gas turbines that burn gasoline, natural gas, diesel, or biofuel. Each turns a generator that recharges or augments the batteries. So the C-X75, which was named in tribute to the company’s 75th anniversary, has an all-electric range of 68 miles, which the turbines can extend to 560 miles. And the battery pack can be recharged using household current in 6 hr.

The axial-flow turbines, made by Bladon Jets, U. K., each weighs about 77 lb and generate 77 kW (94 hp) running at a constant 80,000 rpm, They are mounted in an acoustically insulated compartment directly behind the cockpit and, according to the company, do not generate excessive noise or vibration. Air comes from a variety of vents, including ones behind the side windows and along the roof. Running at a constant rpm lets the turbines operate at peak efficiency. The turbines spin a pair of switched-reluctance generators supplied by SR Drives, U. K. The turbines operate in sequence or together, depending on the situation, to charge the battery pack or send electricity to the 110-lb hub motors. When electricity from both the generators and batteries goes to the hub motors, the concept car can accelerate from 0 to 62 mph in 3.4 sec and have a top speed of 205 mph.

Compared to piston-powered alternatives, the turbines use fewer moving parts and rely on air bearings that need no lubrication. The turbines also don’t need water cooling. And the turbines spool up to operating speed and temperature in seconds, so they can charge the batteries in short bursts without lowering fuel consumption or battery life.

Jaguar engineers even figured out a way to use the exhaust thrust from the turbines: It gets funneled via vanes in exhaust ports to flow over a diffuser and under the vehicle where the shaped underbody uses it to create downforce. To make this safe, Jaguar coated the carbon-fiber diffuser with a zirconia-molybdenum material that protects it against the hot gases.

Aluminum makes up the body and the extruded and bonded chassis, and half that is recycled aluminum. The front grille and cooling vents for the brakes open only when necessary to keep drag to a minimum. And control surfaces in front of the rear wheels automatically adjust at high speeds to direct airflow aft of the wheels to increase stability. And the diffuser includes an active airfoil that lowers when speed increases for more downforce, which increases the grip the tires have on the road.

On the inside, both seat are fixed. It’s the steering wheel, controls, and pedals that adjust to fit the driver. Another innovation in the cockpit is the surround-sound speaker system made up of dozens of efficient, moving-coil speakers in an ultrathin honeycomb pattern lining the doors and rear wall.

© 2010 Penton Media, Inc.

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