Hybrid rally car a first for Citroën

  • 13-Oct-2008 04:07 EDT

Citroën's C4 WRC HYmotion4 combines a 125-kW motor generator driving the rear wheels with a 320-PS (235-kW) gasoline engine driving all four wheels.

Hybrid was a powerful theme at the Citroën booth at the Paris Motor Show, featuring a range of technologies from micro-hybrid stop/start in the C3 Picasso to the concept hybrid rally car of the C4 WRC HYmotion4. The C3 Picasso made its public debut at the show, and the company used its latest model to showcase the next step in its stop/start micro-hybrid technology.

Citroën will introduce the next phase in the development of the system in 2010, based on the Valeo StARS starter alternator system, which the company first used in 2004 for the C3 compact sedan. The next generation of the system will introduce regenerative braking, which Citroën claims will reduce fuel consumption and carbon dioxide emissions by a further 15%. Fitted with the system and the company’s six-speed electronically controlled gearbox, the C3 Picasso show car is said to return 4.2 L/100 km on the European combined cycle, with carbon dioxide emissions of 110 g/km.

With the C4 WRC HYmotion4, Citroën claims a first for a world rally car, in being fitted with a hybrid energy-recovery system. Main components of the system include a 125-kW motor generator connected to the rear differential. A 990-cell 22-A·h lithium-ion battery pack operating at 400 V is positioned above the fuel tank. Both the motor generator and batteries are equipped with their own cooling systems. The radiator is positioned under the right-hand side of the floor. A separate electronic control unit manages the system’s power electronics.

Drivers can choose from four operating modes. Internal combustion engine only is the car’s most frequently used mode. On rally stages, the energy-recovery system can be activated to improve resistance to brake fade and also to charge the batteries. Similarly, the car can be powered from the electric motor only with energy recovery, a mode that may be useful for non-competitive sections. Finally, boost mode can be used to boost torque by 300 N·m (221 lb·ft) for a limited period.

The C4 WRC HYmotion4 is powered by a turbocharged gasoline engine developed from the PSA Peugeot Citroën EW10J4S 2.0-L engine producing 320 PS (235 kW) at 5500 rpm. The engine is controlled by a Magneti-Marelli MHT460 ECU. The transmission system incorporates a triple-plate carbon clutch, four-wheel-drive system with mechanical front and rear differentials, an active center differential, and six-speed automated sequential gearbox. In total, the car has a total mass of 1350 kg (2976 lb).

Citroën has shown its C-Cactus concept at a number of recent European shows. The car, which features an interior devoid of unnecessary equipment, made its appearance at Paris with an electric drivetrain. Equipped with lithium-ion batteries, the car is said to have a top speed of 110 km/h (69 mph) and a range of 150 km (93 mi).

Citroën envisages a range of potential power sources for the car from an optimized 1.0-L gasoline engine, a two-wheel-drive internal combustion/electric hybrid, as well as the all-electric variant.

Hybrid power was also central to the Hypnos design concept. In this case, the system is a PSA Peugeot Citroën hybrid platform also seen at the Peugeot booth in Paris. It is a parallel hybrid with four-wheel drive, but in this case the 200-bhp (147-kW) 2.0-L diesel engine drives the front wheels via a six-speed automated gearbox and the single 37-kW electric motor, offering 200 N·m (148 lb·ft) of torque to drive the rear axle. Like the C3 Picasso on display, it also features an automatic stop and start system with energy recovery. Citroën claims a European combined-cycle fuel consumption of 4.5 L/100 km with carbon dioxide emissions of 120 g/km.

Describing the Hypnos, designer Carlo Bonzanigo told AEI, “We tried to give the status of a sedan, the dynamism of a coupe, and two attributes of an SUV—the high driving position and a feeling of protection.”

Interior designer Leanne Early was inspired by visiting the Milan Furniture Fair: “I wanted to do something really innovative and create a sculpture in an interior.”

Her inspiration for the interior's central tunnel came from a traditional hand-held fan. “I took a dowel, started drilling holes, and took about a hundred sticks and put them on the central axis and started twisting and creating the spiral. Then I realized that it looks like seats, so I started looking at the seating. The whole idea was that you had the seats and then you could almost pull pieces out from the spiral, like the screen or the controls or a table. The ‘blades’ start from the dashboard and start spiraling. They integrate into the seats. The seats integrate into the rear seats, and the rear seats integrate into the boot area.”

Small LEDs inside the air vents match their color to the air temperature—red for warm and blue for cool. The brightly colored leather is spray-painted. Color is also used to create a calming interior. A ceiling mounted camera uses anthropometric data to judge the driver’s state of mind and adjusts the cabin lighting and air freshener fragrance accordingly.

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