Thank you for the Remundo info, indeed, perhaps it would be wise to have this message on this subject.
By tradition and in particular in France there is mistrust with regard to an innovation which would question an established system. Industrialists and financiers seldom scient the branch on which they are installed even if a major innovation comes to present a general economic interest because it is much more lucrative to manufacture mountains of pistons, connecting rods, crankshafts, cylinder heads, etc. than machines comprising few components and 10 times cheaper.
These industrialists are therefore reluctant to embark on new technologies which they are wary of and which could present chances of random success, particularly if we take the example of Citroën for the Wankel engine around the 1970s.
On the other hand, these same manufacturers can pursue without taking into account the sophistication of existing engines to insidiously stimulate their customers.
In the example, the pinnacle is reached with the adoption of the concept Mce5 VCR (variable compression ratio) planned (perhaps) on engines of French firms while VCR concepts much less sophisticated (eccentric on crankshaft bearings, or engine block in 2 removable parts) have already been made by several engine manufacturers but ultimately abandoned due to performance not up to the additional cost generated by the concepts.
On the Mce5, 4 additional pistons are added to actuate the VCR mechanism which also has a very complex control servo.
It is therefore useless to specify that the increase in mass and volume of the engines can include this concept which paradoxically uses (barbaric term) the “down sizing” which consists in force-feeding an engine of smaller displacement, therefore normally lighter, for obtain the same power as a larger displacement engine thanks to a modern double-stage multi-fin turbo-compressor, the supercharging of which is ensured in particular by electronically-controlled adjustable fins.
This choice lets perceive that there is whole antinomy by adopting the VCR (variable compression rate) which is supposed to reduce consumption whereas simultaneously is used a turbo-compressor which, him, it is very greedy in fuel because it is it's no secret that the fueling of a gasoline engine considerably increases consumption compared to the naturally aspirated engine due to an imperative reduction in TC to avoid detonation and the drop in torque that the Turbo generates by braking the gases exhaust.
When you imagine the cost of a double-stage turbo-compressor which is probably as high, in its salt, as a “radial turbine as standard, no need to think a lot to understand what the price of the vehicle with the concept will be. , as some say: sometimes we fall into delirium.
On the other hand the interest of the turbo is major and indisputable on the diesel which do not undergo a disturbance of the gas column due to the suction flap of the petrol engines which creates a depression or suction braking the piston and thus reducing the torque when are at low load.
Indeed, on diesel there is always complete filling of the cylinder; consequently the air compressed by the turbo exerts a favorable thrust on the piston which increases all the more the torque of the diesel engine whereas one finds oneself conversely on the petrol engine which in addition is already limited to 10 in its compression ratio due to the detonation phenomenon.
Of course, the designers of the Mce5 pride themselves on the concept of being able to lower the volumetric ratio to 6,5 so as to allow better force-feeding the engine and obtain high torque and power at low revs, a ploy especially intended to impress the layman who is unaware that with a turbo-compressed engine one can obtain higher powers. at 150hp / l for decades, they were also used a lot in Formula1 around the 1970s.
The vehicle using the concept will probably interest a limited clientele, not caring about the financial aspect but especially fond of originality and sensations.
It therefore appears that the Mce5 solution intended to allow savings to be made both for the construction of the engines and for the reduction of their consumption is not the most convincing due to cheaper and less complex choices from other firms.
Points seemingly debatable of the Mce5 concept:
1 / complexity of the link mechanism with racks, intermediate oscillating toothed wheel whose high mass can only encourage to reduce the engine speed.
2 / production of 8 cylinders and 8 pistons instead of 4 on the conventional engine.
3 / larger and heavier engine than a conventional engine of the same displacement.
4 / very specific and expensive operations of forging, stamping, machining, rectification and special heat treatments of the elements of the link mechanism.
http://www.youtube.com/watch?v=UEtm2y1yXnI&NR=1
Only the Vtec engine (Honda patent) and a few other almost similar systems have made it possible to achieve very significant reductions in consumption for more than 20 years.
Its very simple principle consists (via a device associated with the camshaft) in allowing the closing of the intake valves to be delayed in order to keep only the optimized quantity of air necessary for mixing, the excess air not necessary (at low load) being released just before closing the intake valves.
The Vtec principle therefore makes it possible to dispense for the most part with the throttle valve or intake flap mentioned above in order to reduce the phenomenon of suction generating an increase in consumption.
My vehicle with the Honda 16v Vetec engine consumes about 15% less than those with conventional engines. However, to obtain optimum consumption reductions it would be interesting to associate the Vtec principle with the VCR. It seems that this has not yet been attempted.
If we look at the charts of gasoline engines with reduced consumption, turbo-compressed engines do not appear there.
Using a turbo-compressor to reduce the displacement seems to be heresy.
In my opinion, to considerably reduce consumption, we must do the opposite, that is to say increase the cubic capacity by passing for example from 1,5l to 2,5l to finally obtain, thanks to the Vtec system, a partial filling of the cylinders, in other words, in this case, the volume of 2500cm3 would only be filled at 1500cm3 at TC10 for a prolonged expansion rate, over 2500cm3, which would become approx. equal to 17.
According to this configuration, substantial reduction in consumption can be achieved without real additional manufacturing cost.
Another fairly well-known process, Lokheed's "Turbo-compund", makes it possible to recover losses from the exhaust and reduce consumption by more than 10%. Its principle has also been successfully adopted for a few years on SCANIA and VOLVO trucks.
The fairly simple system consists in adopting an exhaust turbo, the shaft of which will be connected, via a variator and a gear reduction gear to the crankshaft or other engine shaft.
http://www.routiers.com/sejtbases/routi ... scania.pdf
In the context of the planet's exhaustible resources in the short term, I advocate for all the processes to save them.
