|Peugeot 2008 HYbrid Air. The energy tank can be seen in the central tunnel, and the low-pressure tank at the rear. Click to enlarge.|
The new hybrid combines a 3-cylinder gasoline engine with a compressed air/hydraulic motor/pump system comprising an energy tank containing pressurized air installed under the body in the central tunnel; a low-pressure tank at the rear suspension cross member acting as an expansion bottle; and a hydraulic unit consisting of a motor and a pump installed under the hood on the transmission.
The compressed air/hydraulic system will assist, or even take the place of, the gasoline engine during the phases which consume the most energy, i.e. acceleration and moving off.
An EGC (Electronic Gearbox Control) manages the distribution between the two power sources; it replaces the mechanical gearbox and in addition offers automated gear changes.
The 3-cylinder gasoline engine in the 2008 HYbrid Air features optimization of weight compactness by means of maximum integration of components; a reduction of internal friction by means of the use of Diamond Carbon coating, thermo-management and split-cooling for faster warm-up. The HYbrid Air is compatible with existing platforms, benefitting occupant space, modularity and the volume of the gasoline tank, which remains unchanged.
Operating modes. The system offers three modes: Air (ZEV), Gasoline, and Combined. In the Air (ZEV) mode, only the energy contained in the compressed air tank will drive the vehicle. As it depressurizes, the air occupies an increasing amount of space in the energy tank and so displaces a corresponding volume of oil. This is an energy carrier which supplies the hydraulic motor coupled to the drivetrain. As the engine is switched off, the vehicle moves without consuming any fuel or emitting any CO2. This mode is especially suited for driving in urban areas.
In Gasoline mode, only the 1.2-liter VTi 3-cylinder gasoline engine powers the vehicle. This engine benefits from the latest technology to offer, compared to the previous generation, a reduction in weight of 21 kg, friction reduced by 30% and advanced thermo-management to reach the optimum operating temperature more quickly. This mode is particularly suited to steady speeds on main roads and motorways.
In the Combined mode, the gasoline engine and hydraulic motor operate simultaneously to move the vehicle in proportions adjusted according to the situation to achieve optimum fuel economy. Adaptable, the HYbrid Air can supply the hydraulic motor from two sources. While the quantity of energy contained in the pressurized air tank is sufficient to fulfill the driver’s request, the hydraulic motor operates using this source. Then, if necessary, it can be supplied by the hydraulic pump directly. This mode is intended in particular for the transitional phases in urban areas and on the open road (moving off, acceleration).
The energy tank is filled in two ways. On deceleration (on braking or releasing the accelerator), the speed is reduced not by application of the brake pads to the brake discs but by the resistance to the compression of the air in this accumulator. The alternative consists of filling by restarting the internal combustion engine; in this situation, some of the energy produced by the gasoline engine is used to compress the air. In both cases, the maximum energy capacity of the pressurized accumulator is reached in just ten seconds.
The adaptability of the HYbrid Air technology allows it to offer numerous advantages, Peugeot suggests. By using tried and tested components, its durability makes it suited to a wide range of road conditions encountered across the world.
According to Peugeot, customers of cars and light commercial vehicles in segments B and C equipped with the Hybrid Air technology will experience:
urban driving in Air (ZEV) mode up to 80% of the time, with no fuel consumption;
a resulting 45% reduction in fuel consumption when driving in urban areas;
smooth driving due to the automation of the transmission; and
unchanged occupant space and modularity and unchanged fuel tank capacity.
Following a homologation cycle test, the HYbrid Air achieved CO2 levels of just 69 g/km.
Peugeot says the HYbrid Air is a key step towards 2.0l/100 km (118 mpg US) in association with other technological advances. This level of fuel consumption will be achievable with the contribution of the innovations relating to the gasoline engine and the platform, the company said. Regarding the engine, the down-sizing strategy, the thermo-management and the combustion are important progress areas. The platform is the modular construction component at the heart of the design and manufacture of any new model. The use of lighter materials and innovative industrial processes permit significant reductions in weight.