HSD with tiptronic sequential manual shift mode?

The change would only require software, other than the shift switches (paddles). With HSD this wouldn't be manual shifting in the traditional sense. It would be a drive-by-wire input requesting the computer to change the transmission parameters. The computer still gets the final say as to whether the input makes sense.

Unquestionably this sort of manual shifter could be used to force the ICE to run at higher RPMs and lower torque, thereby reducing lag time when you hit the gas. However, if performance is the real objective you would do better having performance mapping for the automatic curve. The automatic curve has essentially an infinite number of shift points, which is impractical for human shifters.

The real reason to have something like this is for fun. There is no practical or engineering reason to include manual shifters, but they can be fun. I could see Toyota adding the option to some sports version of a higher performance hybrid. I don't see it being added to a mileage king like the current Prius.

Tom

 

"....is for fun..."

First, let me go on record as saying the power level of the Prius is perfect for the "job", market, for which it was designed.

That being said, a manual shift is no "fun" without at least a tad of "boy racer" mentality power level, a "surplus" of engine power. Then there is also the issue of the danger, FWD danger, of an improper, inappropriate, downshift on a slippery surface. This latter could be overcome via the use of VW's new engine DBW up-rev technique but that would require yet another firmware revision.

Convert the current Prius Atkinson cycle engine to use the Miller Cycle, add a SuperCharger(***). You could get the same FE levels as today but with extra "punch" that would warrant a manual shift PSD mode.

*** A small, lightweight carbon fiber composition positive displacement SC driven by the ICE/hybrid battery via a downsized version of the PSD. No throttle plate required, the SC only provides enough intake airflow for current power demands. Prius highway FE would probably be improved.

 

The Miller Cycle is supercharged, so you don't need to add one. If it isn't supercharged you have what is now considered the Atkinson Cycle like that used in the Prius. Of course we all know that a real Atkinson Cycle engine has that weird dual crank shaft arraignment, but the only purpose that served was to beat the patent on the Otto Cycle.

Tom

 

It does reduce internal friction, or at least shifts it to an area where it is more easily addressed. Honda's Ezlink engine isn't an exact copy of Atkinson's, but is using the same principles.

If we are going to start a wish list for a sport Prius, skip the super charge and use a hybrid turbo charger. Which, to be honest, is just an electric supercharger with an exhaust spun turbine.
[ame=http://en.wikipedia.org/wiki/Hybrid_turbocharger]Hybrid turbocharger - Wikipedia, the free encyclopedia[/ame]

 

An Atkinson engine does not have enough power left in the exhaust to spin a turbine, only enough, barely, to keep the catalyst up to operational temperature, ~800F. Same thing applies to the "hybrid" turbocharger, not enough energy in the exhaust of an Atkinson engine.

 

Sorry, really should have said "by adding a...".

 

With the turbine mechanically isolated from the compressor, wouldn't it be possible for it to be optimized for the lower energy exhaust? Granted, it wouldn't be enough electric generated for it power the compressor/super charger for sustained periods on its own, but that would be some charge going into the traction battery to offset the supercharger's draw.

 

If the exhaust energy were truly destined to be "wasted", as is the case for most turbocharged engines, then it would be best to have it spin a turbine.

But as it is it's best to spin the MG.

 

Well, we could just drop the compressor from the hybrid turbo.

 

The only problem is cost with your plan. You need to design the engine for the miller cycle which is to slightly reduce the native compression, but make it strong enough to work with boosted compression. Miller cycle with a hybrid turbo will eliminate turbo lag and provide low rpm torque. Toyota is experimenting with a non-hybrid turbo to increase efficiency.