Quark fuel-cell roadgoing QUAD
Peugeot's futuristic prototype two-seater, 4WD Quark was built to showcase the company's fuel cell technology. The Quark has a removable interactive interface, which appears to be a PDA on steroids. The unit serves the same purpose as an ignition key and is used in conjunction with an instrument panel. Positioned in its housing, it provides information concerning the traction system and the fuel cell, speed, SATNAV, etc ... protected by a small transparent and waterproof cover, it allows the vehicle to be started when in place and immobilises it when removed. Far more than just a show floor dummy, the Quark competed successfully at the recent Michelin Bibendum Challenge.
Apart from the innovative PDA concept, the vehicle looks set to create its own class of roadgoing four wheeler, quite similar to the 4WD off-road machines which are selling so well in America at present, yet created as a low-emission inner-urban fuel-cell vehicle.
An electric motor drives each of the four 17'' diameter wheels, themselves connected to the chassis by means of triangular wishbones.
In fact, it is in town that the main qualities of the fuel cell - noiseless operation and absence of pollution at the point of use - are most relevant. In addition, when used in and around town, i.e. in driving conditions that involve frequent deceleration phases, it is possible to use the vehicle's electric motors to enable regenerative braking, thereby recovering energy expended during deceleration at no cost and reducing the vehicle's overall fuel consumption.
The fuel cell supplements electrical energy supplied by a Nickel Metal Hydride (NiMH) battery consisting of 40 individual cells, each with a voltage of 7.2 volts. The battery can therefore provide a nominal overall voltage of 288 Volts. In parallel, PSA Peugeot Citro‘n have also developed new solutions to simplify the fuel cell and reduce its size to help integration into more compact vehicles.
Firstly, the fuel cell of the Quark is not water-cooled, but air-cooled. This avoids the need for a bulky water-cooling system and removes one of the major constraints of the fuel cell: the incompatibility between pure water/negative ambient temperatures. When the ambient temperature hits freezing point, water can cause irreversible damage to a water-cooled cell, since an anti-freeze suitable for a fuel cell has yet to be developed. It is therefore not necessary to garage the Quark regardless of weather conditions.
The Quark uses a 9-litre hydrogen tank at a pressure of 700 bars. Requiring the same amount of space as a 350 bars bottle, this makes it possible to increase the quantity of on-board hydrogen and thereby extend the vehicle's range. Over a complete cycle, the latter is around 100 km (up to 130 km in economy mode) and the Quark has a simple and rapid method of refilling the vehicle with hydrogen, with a "plug & drive" system that makes it easy to replace an empty bottle with a full one.
The Quark power train is innovative. Electrical power supplied by the batteries and the fuel cell is transmitted, not to a central motor, but to four individual electric motors located in each of the vehicle's wheels. Each motor provides a maximum torque of 100 Nm, a continuous output of 2.5 kW and a maximum output of 7 kW. Thanks to its four individual motors, the Quark therefore has a maximum torque of 400 Nm, a nominal power of 10 kW and a maximum power of 28 kW.
Electrical current from the batteries is controlled by a converter, which supplies the stator windings and generates a rotating magnetic field. This rotating field drives permanent magnets attached to the rotor, itself connected directly to the hub of the wheel, which therefore follows the rotational movement of the motor's magnetic field. This technology offers advantages in terms of the weight and space of the motors, as well as their power efficiency.
The motor housing (stator) serves as a pivot. Due to the fitment of four individual motors, the vehicle has permanent four-wheel drive. An electronic control module controls the motors independently. It supplies torque in accordance with the demands requested by the driver (controlled current). This module, combined with all four individual motors, serves the purpose of the differentials on a traditional vehicle. In addition to regenerative braking, the system can accommodate advanced functions (not implemented on the demonstrator) such as ABS, ESP, cornering assistance (at very slow speed) to reduce the turning circle radius by provoking wheel slip.
The braking system combines regenerative electric braking and hydraulically controlled mechanical braking acting on discs. The braking control regulates both braking modes so that electric braking takes priority over hydraulic braking (ensuring deceleration of around 0.3 g), which is beneficial to the energy balance.