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Brushless Electric-Wankel Hybrid Engine.

A Conventional Wankel engine, with an inbuilt electric motor.
  (+6, -1)
(+6, -1)
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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...

bs0u0155, Sep 18 2012


       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.
tumblewit, Sep 18 2012

       Look up "Curie Point". A Wankel engine will generate a lot of heat. Heat is bad for permanent magnets....
Vernon, Sep 18 2012

       One major benefit of hybridization is that the engine and subsequent friction therein may be negated when it is not needed.
WcW, Sep 19 2012

       [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.
DIYMatt, Sep 19 2012

       //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 Wankel.
bs0u0155, Sep 19 2012

       //rotor tips// and the other surfaces of the rotor, against the sides, no ?
FlyingToaster, Sep 19 2012

       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.
bs0u0155, Sep 19 2012

       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 lay in 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.
Alterother, Sep 22 2012


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