Andy, Hehe - I see that hit home at a very +ve moment for changing the world
The future is Diesel?
Mmmm, is it?
HarryMann wrote: The Otto cycle is in fact more efficient than the Diesel?
True or False
== ==
People like Toyota don't mess about, and they won't be resting on their laurels I expect.. they are one of the few companies going for zero emissions and high mpg in a serious way. And they are doing it
all in-house, nothing in the Prius is contracted out, or outsourced - unheard of.
Whilst the VW Tdi and many equivalents are getting pretty good fuel consumption with diesels, they certainly aren't getting it without emssions, nor when that power is really used .
The 2004 Prius is breaking new ground in putting a proper hybrid vehicle out there in the marketplace -
credit where credit is due?
Its also no slouch, 0~60 in 10.1s is pretty respectable I'd say, for what is now a midi sized car, not a mini. The original 1275 Mini Cooper 'S' was 10 secs. and few complained about that back then.
If the first generation Prius broke con-rods I doubt this latest one will, I just can't see Toyota standing that for long, unlike other mfrs.
The cranked con-rod is to reduce the offset thrust during combustion that creates high piston/wall friction.
They work on an Atkinson cycle that is a slight variation on Otto - something along the lines of delaying the inlet valve opening to reduce cylinder filling. Seems mad?
But by then building in a higher compression ratio to start with (13:1 +) the effective compression is restored. You then end up with a greater expansion ratio, which is what leads to a thermodynamic cycle with greater efficiency.
Running in full hybrid mode, well over 50mpg in town and about 50 mpg motorway, for an average over 50mpg. I've said many times here that I am convinced people kid themselves silly with realistic mpgs they get, and I think they do, even with modern diesels. For one they seriously ignore any bad figures due to heavy town driving, and always just quote their long run 'best' figures, as well as not serioulsy record their total fuel/mileage over a full year. If they did it would almost always disappoint!
50mpg day in day out without driving stupidly carefully is amazing, and almost zero emissions - but no i wouldn't buy one - yet! One day we may have to
=== Ah! the NSU/Mazda Wankel Question ===
Whatever success Mazda has made of it - and to engineer something like that even reasonably succesfully has got to be given a least a silver star, if not a gold on their homework - they're still making them and still selling them and some really like them, no doubt about it.
But apparently it has serious thermodynamic problems, which are more important than any of its dreadful mechanical complexities could ever be. It just can't be made to be clean and efficient, even though it might seem the ideal candidate. It's just simply the first rotary IC engine, but happens to have been a very bad choice of rotor/combustion chamber design.
It compresses fast first and then slowly, and expands slowly and then fast - to some extent identical problem with the piston/crankshaft engine. The piston sits around at TDC when in fact that's the last thing you want it to do. And it has very heavy constraints over combustion chamber shape. And is 'orrible to cool and lubricate as well, and overly complex to make, witness Mazda devoting a lifetime of years getting it 90% there. It took Herr Wankel 30 years to even get a shape worked out.
In fact about its only + point is that it is entirely rotary, but unlike the quasi-turbine, can't really support continuous combustion.
Just a ramble on what might be coming in 5 or 10 years time - anyone got a CNC mill and we can have a go
Simple innit...
The Future is Multi-Fuel