With the’Alfa Romeo Tonale, the house of the biscione officially begins its electrification process. The heart of the compact SUV will be the new 48 Volt hybrid system, capable of supplying power directly to the propeller shaft and supporting the combustion engine in the most delicate phases of use, allowing a reduction in consumption and emissions. Based on the numbers released by Stellantis, it is possible to reconstruct the characteristics and the basic architecture of the hybrid that will push the Alfa Romeo Tonale.
That of the Tonale looks like a hybrid system in parallel, with the electric motor generator capable of delivering motive power to the wheels parallel to the combustion engine. With Tonale, Alfa Romeo thus introduces regenerative braking to its range, with the possibility of powering the electric motor through the energy recovered during braking that would normally be dissipated in the brakes, allowing a tangible reduction in fuel consumption. However, the greatest advantages in terms of efficiency derive from the possibility of using the hybrid system to push the vehicle in low-speed maneuvers such as starting, parking, reversing and driving in traffic. In such circumstances, in fact, the heat engine it normally works at low speed and low torque, conditions to which the worst values of efficiency and consumption correspond. In these circumstances, the electric takes over, with the thermal unit that can be used directly at higher speeds when the combustion efficiency is better. By delivering motive power directly to the transmission, the Tonale hybrid stands at a higher level than traditional BSG systems in which the electric motor works solely to support the thermal one.
On the Alfa Romeo Tonale, the electric motor generator is installed in place P2, that is to say downstream of the thermal engine and before the seven-speed gearbox. Installation P2 assumes the presence of an auxiliary clutch between the electric motor and the combustion engine, so that, in the phases in which the propulsion takes place entirely in electric, it can be opened automatically to disconnect the thermal engine and not to spend further energy in its dragging. The 48 V electric motogenerator guarantees a maximum power of 15 kW, equivalent to about 20 horsepower, and a torque of 55 Nm. Thanks to the transmission ratio of 2.5: 1, however, the electric torque delivered to the shaft upstream of the gearbox is 135 Nm. This confirms how much the ‘hybrid Tonale has been conceived to guarantee significant support at low speeds, in the maneuvers defined as e-Launch, that is the start entirely in electric, e-Queuing, that is to say driving in traffic, e-Creeping, for the recovery between 0 km / h and the minimum in first gear, as well as the e-Parking. Outside the Plug-In version, the electric energy recharged during braking is stored in the 48 V lithium-ion battery, with a capacity of 800 Wh and a maximum power of 22 kW. The total volume of the accumulator is in the order of 11 liters, outlining an energy density around 73 Wh / l and of power equal to 2 kW / l.
The Alfa Romeo Tonale Hybrid will be powered by a 130 horsepower heat engine, but an enhanced version will also be available 160 horses and a maximum torque of 240 Nm. The difference lies in the use of the variable geometry turbo (VGT), able to reduce turbo-lag and improve torque and efficiency at low revs. Once again, it is clear how much Alfa Romeo has focused on both the architecture of the hybrid and the preparation of the combustion engine on pick-up performance and on the availability of torque at all speeds. Furthermore, as in many of the hybrid engines, the combustion engine works according to a Miller cycle, with the opening timing of the valves calibrated to extend the expansion phase with respect to the compression, for a better exploitation of the energy released during combustion to the advantage of efficiency and consumption. About, the double phase variator allows a further degree of freedom in the management of the valvesand, to adapt the work cycle of the heat engine to the speed and torque demand.
In spite of the relatively low hybridization ratio, with the power of the thermal that continues to outclass the electric one, the hybrid of the Alfa Romeo Tonale still stands as an important aid in different driving conditions. Furthermore, it should not be forgotten that the Tonale is only Alfa Romeo’s first step in its path of electrification, of which important innovations are expected in the medium-term future.
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