By March 5, 2011 Read More →

Audi Q5 hybrid quattro

The 2.0 TFSI in the Audi Q5 hybrid quattro has a displacement of 1984 cc. Its output is 155 kW (211 hp), with the maximum torque of 350 Nm (258.15 lb-ft) permanently available between 1500 and 4200 rpm. The four-cylinder unit combines gasoline direct injection with turbocharging. The Audi valve lift system (AVS) further increases power, torque and efficiency by switching the stroke of the exhaust valves between two stages depending on the load and rpm. The 2.0 TFSI has been overhauled in some respects for use in the Audi Q5 hybrid. The drive of the ancillary units has been dropped, and the crankshaft bearing and fine tuning of the turbocharger have been adapted to the specific demands. A secondary air system at the cylinder head makes sure that the exhaust gas treatment cuts in particularly fast. Integrated in the engine control unit, the so-called hybrid manager controls the efficient change and smooth transitions between the operating modes.

The 2.0 TFSI and the electric motor of the Audi Q5 hybrid are mounted directly behind one another as a parallel hybrid system – a straight-line concept with impressive efficiency. Together they have a system output of 180 kW (245 hp) and a system torque of 480 Nm (354.03 lb-ft). The Audi Q5 hybrid sprints from 0 to 100 km/h in 7.1 seconds. In the normal cycle, the Audi Q5 hybrid quattro consumes 6.9 liters of fuel per 100 km (33.60 US mpg) – that corresponds to a CO2 emissions level of 159 g per km.

A largely modified eight-speed tiptronic serves as the power transmission without the aid of a torque converter. Its place is taken by the disk-shaped electric motor, combined with a multi-plate clutch bathed in oil, which couples and decouples the electric motor and the TFSI. The innovative decoupler operates precisely and smoothly in any situation. The highly comfortable and fast-shifting hybrid gear unit contributes significantly to the efficiency of the Audi Q5 hybrid – its eight gears are widely spaced. When the 2.0 TFSI is deactivated, an electric pump maintains the oil pressure in the hydraulic system to safeguard the convenient start-stop feature.

The radiator tank in the engine bay houses the power electronics. The so-called pulse-controlled inverter serves as a controller between the battery, which outputs direct current, and the electric motor that operates on alternating current. Innovative technologies keep the volume and weight of the power electronics low, with cooling provided by a separate low-temperature water-filled circuit. The component includes a DC/DC converter that couples the electric consumers in the 12 V electrical system with the high-voltage network. A permanently excited synchronous machine serves as an electric motor, as a starter and – during deceleration – as an alternator. It delivers up to 40 kW (54 hp) of power and 210 Nm (155.63 lb-ft) of torque. The electric motor is integrated in the engine’s cooling circuit.

A lithium-ion battery system, weighing merely 38 kg (83.78 lb), serves as the energy store for the electric motor of the Audi Q5 hybrid quattro. The compact unit with its 26-liter (6.87 US-gallon) capacity is positioned in a crash-safe area under the loading floor, with hardly any detriment to the luggage compartment. The battery consists of 72 cells; at 266 volts its nominal energy is 1.3 kWh and its output 39 kW. The lithium-ion battery is cooled by air in two ways, depending on the requirement. At low-temperature load, it draws temperate air from the vehicle interior by way of a fan. If its temperature exceeds a certain limit, a separate refrigerant circuit is activated. It is coupled to the main climate control system of the vehicle and uses a separate evaporator. This efficient, active cooling mechanism is a major factor in the hybrid system’s high electric availability and sets the Audi Q5 hybrid quattro apart from many other hybrid vehicles.

The Audi Q5 hybrid quattro can be driven in five operating modes. Driving with the combustion engine alone, with the electric drive alone or in hybrid mode is possible, as are recuperation and boosting. At a standstill – before starting or at a traffic light, for instance – both drive sources are deactivated. In this “comfort” start-stop mode, the climate control system remains active. Once the driver releases the brake, the Q5 hybrid quattro begins coasting. It can be driven up to 100 km/h (62.14 mph) under electric power – with almost no noise or local emissions. At a constant speed of 60 km/h (37.28 mph), it has a range of 3 km – enough for many residential areas and city centers. The driver can change between three programs using a button on the center console or the selector lever. The EV characteristic map gives priority to the electric drive in the city, the D mode controls both motors for optimal consumption, and the S mode as well as the touch control gate of the tiptronic are designed for a sporty driving style.

If the driver accelerates quickly, the combustion engine takes over and delivers traction. Now the electric motor’s main job is to power the on-board consumers and keep the accumulator battery charged. In quick acceleration, or “boosting,” the electric motor operates together with the TFSI; at full throttle in the S mode the full system output is briefly available. In such cases, the hybrid drive supplies the propulsion power of a large naturally aspirated engine, but with far more efficiency. When the driver releases the accelerator, the electric motor acts as an alternator and recovers energy. In most situations the TFSI is then decoupled from the drive system so as not to cause any drag losses. The electricity recovered by the electric motor here and in braking is buffered in the lithium-ion battery. If the driver brakes only slightly, the electric motor performs the deceleration by itself; in more forceful braking the hydraulic braking system is simultaneously activated.

Quattro permanent four-wheel drive reliably applies the power of both power units to the road in any situation. In the normal condition the sporty drive is emphasized at the rear; if need be, it transmits most of the power to the axle with the better traction. The sophisticated chassis includes many aluminum components for reduced weight. The Audi Q5 hybrid quattro is capable of pulling trailer loads of up to 2000 kg (4,409 lb). The steering is based on an electromechanical system. The system is extremely efficient because it consumes no energy when driving straight ahead. The brake servo is additionally supplied by an electric vacuum pump. A complex control strategy adapts the braking to the conditions of electric driving and energy recuperation.

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