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Variable Compression 2


The invention of the company FEV aims for the solution of an old problem of the petrol engine in a relatively easy way. Mechanically, an infinitely variable change of the compression ratio is possible. What makes the design special is that it is relatively easy to integrate into the present series production. Also the increase in weight of the engine is acceptable, not to mention potential problems with the sealing and the mechanical strain of other solutions.

In combination with charging of the engine, engineers prognosticate consumption savings of up to 25%. This number refers to the part load, which is especially important in practice, and also comes about by using fewer cylinders with equal performance. Hopefully, the torque development of turbocharged engines for the lowest speed range approaches that of cubic capacity-bigger aspired engines. It will be interesting to experience the engine noise with the decreased cylinder number and the higher compression.

How it works

Because precise publications are not yet published, only the principle can be explained here. Very often simple is economical. Thus they implemented additional eccentric journal bearings to the main bearings of the crankshaft. The eccentric main bearings are being turned steadily at every journal bearing by a segmented gearwheel. The thickness of the gearwheel disk takes its toll for the bearing width. For the gear rim, however, there is enough space further outside. It may jut out above the crankpin - different than it is displayed above. In this case, the oil pan needs an additional shaft which moves the cog segments via a servo motor.

The side forces may be critical in the middle of the control range. Here the main bearing axis must probably be aimed anew. Probably it is shifted in the final bearing to the right. The problem of the axially offset presents itself from a totally new perspective.


Is the system - of course, with less effect and a higher mechanical expenditure - also suitable for diesel engines in the part load range?