(Re: As a followup to the single point of using a
small Wankel as the lighter weight back-up engine
(ICE) for what is basically a plug-in hybrid, with
intermediate range (50-60 miles)...
--- Standing Bear wrote:
> Mazda sold this for years in the RX-7 to mixed
success. Problem was always excessive oil
consumption.
True, back then, but perhaps not as relevant to this
envisioned implementation.
This particular point (of using a light-weight backup
ICE instead of more batteries) is worth addressing in
detail for a number of reasons. Mainly cost and
availability.
Look at the alternatives:
- especially when first introduced, any advanced
battery ("bettery") especially if it uses expensive
raw materials like lithium, will be sold at a premium,
and the range will always be considered by some to be
too low. Even the shortest charging-times are far in
excess of filling up at a station, and unacceptable
for long trips. The infrastructure for the ICE is
already in place, which is very important for
marketing.
Now - why rotary instead of reciprocating ICE?
1) The rotary engine is ~half or less the weight of
the 4-cycle ICE for the same power. This would be most
important for a back-up gen-set in a very lightweight
plug-in, using a carbon fiber body.
2) The rotary design can be highly efficient, BUT only
in a narrow (high speed) RPM range. When out of range,
it is not efficient. Fortunately, usage as a gen-set
allows the engine to be used ONLY within that narrow
RPM range of high efficiency. This is also true of oil
consumption.
3) All, or most of NSU's former Intellectual Property
on the basic design has expired (but not Mazda's).
4) Most of the oil consumption problem has been solved
in the latest Mazda version, but anyway, this is not a
big issue with an engine which would only be used
infrequently in a plug-in hybrid.
Hopefully the average driver could go for weeks of
normal commuting or shopping, without the need for the
ICE to kick-in at all; but at the same time, with the
assurance that if she needs to go see Mom over in the
next county, she will not end-up stranded out in the
boondocks on the way back.
> No way to keep it sealed given the odd
> shaped combustion chamber
Mazda's new RX-8 (Renesis engine) brings fuel and oil
consumption within a "better than normal" range for US
4-cycle engines, and even passes California's very
strict Low Emissions Vehicle or LEV standards. This is
stricter than the normal standard.
Actually, this is quite a remarkable transformation
from the old "oil-burner" status. Looking ahead, one
wonders if an advance ceramic version of this design
could not be made oil free? Plus of all engines, Mazda
has shown that the rotary is BY FAR the best design to
use with hydrogen, due to the higher flame speed of
the fuel combined with the inherent high RPM
efficiency of the Wankel. The Renesis using hydrogen
is an amazing 45% Carnot efficiency, which is better
than any auto-diesel and almost as good as the grid
plant.
Yes, hydrogen is way, way off into the future - if at
all- except for this: the in situ hydro-booster
(electrolysis) add-on. That may be looking too far
ahead, for these purposes, so let's stick to what is
available now.
Anyway, this solution is all available now, and I see
the Wankel in a backup role to an intermediate battery
array, as a near perfect solution to the high cost and
high weight of a full plug-in capable of 200 mile
range ... not to mention ... that full plug-in
technology may never happen, given how slow it has
been (historically) to develop the proper 'bettery'
Jones
