For Porsche, building more efficient turbos is one of the keys to the survival of the heat engine. A patent unveils an entirely new, hybrid turbo.
What if Porsche revolutionized the turbo? After its work on synthetic gasoline, and in parallel with the development of its electric range, the German manufacturer is working hard to make the heat engine more efficient. The stakes are high for Porsche: power keep its range of pleasure cars with a heat engine, and be able to delay (or even cancel) the switch from 911 to all-electric. In a new patent revealed by the media CarBuzz, Porsche is preparing a whole new approach for its turbos of the future. Explanations.
The turbo, an imperfect solution
The operation of a conventional turbo is relatively simple. The exhaust gases cause turbine, which she operates a compressor. The latter is responsible, as its name suggests, to compress the air entering the cylinders, to maximize power developed for a given displacement. And, in theory, improve engine efficiency. This is why the standard of « downsizing », the replacement of large atmospheric engines by small heat engines, has spread like wildfire with the arrival of stricter environmental standards in recent years.
When the driver is driving calmly, the turbo is not really driven, and fuel consumption is reduced. When the need for power arises, the turbo is driven by the exhaust and full power is available. But now, the whole is not perfect. A turbo only works at its maximum efficiency in precise engine speed conditions and opening of butterflies. To solve the problem, most manufacturers now opt for smaller turbos, variable geometry turbos, or twin-turbo systems.
The hybrid at the service of turbos
But Porsche thinks it can go even further. Its patent reveals a truly hybrid turbo. Indeed, the turbine is now separate from the compressor. Between the two, an electrical energy recovery system. The idea is reminiscent of the systems used in F1 or endurance racing by hybrid LMP1s. But Porsche goes further, combining here two small exhaust turbines with a large compressor, to benefit both from the efficiency of twin-turbo systems and from the maximum power of a large turbocharger. In practice, small turbines no longer drive the compressor, but recharge a small battery. They can thus be used in the most efficient phases, and disconnected when consumption increases. In return, the compressor is driven by a electric motor, which eliminates the response time of the turbo and allows to vary its use more efficiently.
In short, a truly hybrid turbo which, if its implementation keeps its promises, could offer interesting performance while largely gaining in consumption. The only concern, as often with hybrid systems, is complexity and weight. The next generation of 911 will it be equipped? Answer in a few years.
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