Porsche six-stroke engine: how it works and when it arrives

The Porsche has filed patents relating to the development of an a six times. But how could it work this engine and that advantages would it bring? Let’s analyze all the secrets, starting from the basics of how an engine works and observing the differences compared to a traditional one 4 strokes.

operation: the basics

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To discover how the 6-stroke engine works, let’s start from the concept of “tempo” same in the thruster. It is defined as time every half a revolution of the crankshaft, which corresponds to a movement of the piston. In a traditional four-stroke engine we therefore have a first phase with the phase aspirationin which air is introduced into the cylinder and the piston descends towards bottom dead centre. The second time is given by the piston rising towards the top dead center (compression) followed by lo explosionwhich returns the piston to bottom dead center and subsequently to I unloadwith the piston returning to top dead center and the exhaust valve opening to let spent gases escape. A six-stroke engine like the one that would be patented by Porsche would then six movements of the piston in the same cycle, rather than the four in the case just observed.

operation: 6 times

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But what would these six times be? Naturally, in this case too, we begin withaspiration (the piston drops to BDC), which is followed by compression and then explosion. Subsequently to first explosionhowever, the piston, thanks to a technical solution that we will explain later, does not return to the same one bottom dead center of the aspiration phase, but rather “descends” further, thus allowing dei ducts present on the walls of the cylinder to introduce new fresh air inside the combustion chamber. Simultaneously with the entry of air from the ducts, the valve opens I unload to vent the exhaust gases. The fourth period can thus take place, which in this case is not an unloading phase, but rather one new compressionin which the piston rises, which is followed by a new explosion and, finally, it I unloadwith the piston reaching top dead center and the exhaust valve opening. Thus ends cycle.

Operation: why 6 times?

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The only time”useful” inside a heat engine is that of the phase explosionbecause it is the only one that generates power engine by rotating the crankshaft. In fact, suction, compression and exhaust occur only as consequence of the rotation of the crankshaft itself. So, if a 4-stroke engine has a useful phase out of 4, Porsche’s six-stroke enjoys it 2 useful phases out of 6having two bursts within the same cycle.

operation: the crankshaft

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A question therefore remains to be resolved: how does the piston have two lower dead points different? The secret lies in the fact that this six-stroke engine adopts a crankshaft specially developed, in solidarity with a toothed ring which rotates inside a second, larger toothed ring (see figure above). This pair of additional gears makes it possible toalternation between the two lower dead points. Let’s analyze the situation better. Following theaspirationthe crankshaft completes its half rotation and moves to the position in which the piston is at bottom dead center. At the same time, the smaller toothed ring to which it is integral is located in a position “A”, to which corresponds aheight “X” of the bottom dead center of the cylinder, such that i ducts remain on the cylinder walls excluded outside of the combustion chamber. Compression and unloading then occur, two timeswhich therefore correspond to a revolution of the crankshaft. This rotation is also performed by the smaller toothed ring, which leads the shaft to reach the position “B”to which corresponds aheight “Y” of the bottom dead center of the piston, sufficient to let in in the combustion chamber the air present in the ducts on the walls.

Advantages and critical issues

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Among professionals, this solution has generated numerous questions. On the one hand, we recognize the greater efficiency of a system in which the useful phases are one in threerather than one in four, but on the other hand several questions are raised. In addition of course to the increase in complexity compared to a traditional engine, which therefore involves increased costs and risks of breakages, the unknown remains the consequence of the greater frictiondue to the addition of the new gears. There remains a doubt regarding the lubrication of the cylinder: if the ducts are located below the bottom dead center, where we would normally have theengine oilhow can air get in? In fact, we cannot think of adding the combustion of oil to the equation as in an engine two times (whose intake “lights”, among other things, are reminiscent of the side ducts of this 6-stroke engine). To resolve all these unknowns, all that remains is to wait if this innovative engine will actually come into existence production.