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The leaning tower of Piezo
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Everyone loves Wankel engines, for obvious reasons.
However, they're not so good with fuel consumption.
Hybrid cars developed to alleviate this problem, are
available in many flavors, but boil down to having
independent electric motors and internal combustion
engines linked by electrical or
mechanical means. I
propose joining the two in a much closer relationship. The
device would look and operate like a standard Wankel
engine. However, the rotor contains three powerful rare-
Earth magnets, these will be in the usual conformation of a
3-pole DC motor. The rotor housing will be constructed of
aluminium, with electromagnets embedded in the wall.
Careful optimization will be required to minimize the
distance between the rotor magnets and housing
electromagnets. The rotor may then be driven by
switching current to the electromagnets in the housing.
This will effectively become an eccentric (but otherwise
conventional)brushless DC motor.
With the same rotor being driven by electricity AND/OR
gasoline we have the ability to move the engine as a pure
electric motor, as a pure gasoline Wankel engine, and as
an electrically-boosted gasoline Wankel engine. This would
enable the power and torque produced by the engine to be
semi-independent of the RPM. Secondly, the drive-train
would be much simpler than existing hybrids: the
transmission may be completely conventional and the
electrical component of the engine would function perfectly
as a large permanent-magnet alternator to harvest
electrical energy from kinetic energy. The engine will be
both tremendously compact and simple; several
components become unnecessary: the starter motor and
alternator for example.
There might also be ways of boosting the efficiency of
combustion by using the electrical component to 'resist and
assist' the rotor at various points in the cycle. Not sure
about that though...
||Brilliant idea overall. The Wankel end of that fusion may need to be improved, but the concept is great. Reliability was an issue with the "Wrankle" which is why you don't see many today.
Perhaps you could work a magneto into the design and get rid of more unnecessary parts.
||Look up "Curie Point". A Wankel engine will generate a lot of heat. Heat is bad for permanent magnets....
||One major benefit of hybridization is that the engine and subsequent friction therein may be negated when it is not needed.
||[WcW] A fact which was stupendously lost on the designers of the Chevy Volt. I don't see how this idea is any less efficient then a typical hybrid that connects its electric motor to the regular transmission. The Wankel won't be burning any fuel or creating any more friction than a normal electric motor when running in electric mode.
||//A Wankel engine will generate a lot of heat.//
||Point taken. The system will still work with
induction. The alternative is cooling via radially
fed oil, probably combined with some snazzy
exotic ceramics for insulation. Also, please
remember that the rotor will cool pretty quickly in
the absence of combustion... i.e. the engine
doesn't burn fuel all the time, and therefore total
engine heat won't be as large.
||//The Wankel won't be burning any fuel or
creating any more friction than a normal electric
motor when running in electric mode.//
||I suspect that there will be more friction in my
system, there are only 2 bearings in a conventional
brushless motor. Here, there are 2 bearings (or 1.5
if you're sharing the central one in a 2-rotor setup)
and 3/6 rotor tips moving against the housing.
While it's NOWHERE NEAR the losses incurred in a
reciprocating piston engine... it's still much more
than a motor.
||However, it's simple, compact, light and addresses
the torque&efficiency issues of a standard
||//rotor tips// and the other surfaces of the rotor, against the sides, no ?
||well, no one talks about the sides... always the apex
seals. Presumably the sides are a non-issue in terms
of sealing... not sure about efficiency... not easy
information to find.
||The apex seals are (supposedly) no longer an issue in the
latest generation of Wankels, and there is at least one
contract shop in the US that has developed a retrofit for
older models. As always, the other major concerns seem to
side-loading on the mainshaft and ignition limiting--if the
limiter fails (be it mechanical or electronic), the motor will
blow itself up. Adding the factor of resistance from an out-
of-control dynamo could dramatically enhance the hilarity.
||Other than the detail of operating the motor in electric-
only mode, which would be ridiculously inefficient in
comparison to a conventional brushless motor of
equivalent weight, this is a great idea. [+]
||Some fancy design tricks may be required to prevent the
aluminium rotor from tearing itself apart. Perhaps Mazda
will foot the R&D bill.