Mercedes-AMG new F1 engine
In 2014, Formula 1 introduced a new set of rules requiring all participating cars have engines with turbos and some form of electric hybridization. The approach taken by some teams uses what they call MGU-K (motor generator unit – kinetic) which is the same process used in most road going hybrids like the Prius. When the car slows down, its kinetic energy is converted to electricity which can be used to propel the car when desired. This increases the car’s efficiency, but not the engine’s.
The Mercedes engine uses an approach called MGU-H, (motor generator unit – heat). It recovers energy from the heat in the engine’s exhaust.
Turbochargers and superchargers both increase the power of an engine by forcing more air into it. The supercharger draws power from the engine, but can be tuned to make good intake pressure even at low engine speeds and throttle settings, which in turn provides quick response if power is called for suddenly. Turbochargers recover energy from the hot engine exhaust to turn a compressor, serving the same function as the supercharger. The advantage is that it does not rob energy from the engine, but it can be slow to respond, as the engine has to be making a considerable amount of exhaust before the turbo can generate a significant amount of intake pressure.
The MGU-H is a kind of split turbocharger, with an electric motor-generator bridging the compressor at one end and the turbo at the other. When the exhaust is making more power than is required to run the compressor, the electricity can be used to charge a battery, or to power the MGU-K (if the car has both) to drive the car forward. The MGU-H can also use battery power to increase the speed at which the turbo spools up, making power delivery much quicker and predictable.
Mercedes positions the turbo and compressor at far ends of the engine, with the MGU-H occupying the valley of the V6 engine. This means that the compressor is isolated from the hot exhaust and so does not need as much intercooling.
Audi SQ7 Engine
Audi’s new 4-litre turbo diesel V8 is a brand new engine.
It uses two turbochargers which are both fed by one of the two exhaust valves per cylinder. Under low load one turbocharger is kept idle by not opening the exhaust valves connected to it. This forces more exhaust to the other turbo, helping it respond faster.
Under high loads, all exhaust valves are opened and both turbos are used to force air into the intake.
And when all this trickery isn’t enough, an electric compressor fed off the car’s 48V electrical system can be used to add more air to eliminate turbo lag.
The Principles
Principle 15 – Dynamics: Mercedes is able to direct electrical power to and from their turbocharger as the need arises, either to direct more power to the wheels or to spin up the turbocharger for immediate power. Audi is taking control of the flow of exhaust to spin up one or both turbos to reduce turbo lag.
Principle 1 – Segmentation: Audi has segmented the flow from the pair of exhaust valves so that under low load the exhaust is directed to a single turbo.
Principle 24 – Intermediary: Mercedes is using battery storage as an intermediary. Whereas normally turbo power can only be derived from exhaust gases when they are being produced, they are taking that power to charge a battery which can later be used to power the compressor.
Principle 6 – Universality: Both Audi and Mercedes are incorporating battery storage in these cars which in turn can be used for powering the drive wheels and for driving more air into the engine. In Audi’s case, the same battery storage can be used for active suspension control, as well.
