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Thread: A rotary gear engine

  1. #1 A rotary gear engine 
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    I could imagine an engine disign and whish to know what could be
    problems with it.It is similar to Wankel engine but difference is that
    it uses few gears.It has a round combustion chamber with teeth inside
    all around it.Inside there is a few gears: a central gear which is connected
    to a shaft and designed in a way that it could rotate only in one direction.
    and two or three more gears which serve like mediators between central
    gear and inner teeth in a combustion chamber.So it is somewhat similar to
    Wankel but somehat different design.


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  3. #2  
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    The Wankel engine was a bust, producing poor fuel efficiency and high exhaust emissions. How would your engine design solve the problems of the Wankel?


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  4. #3  
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    How would your engine design solve the problems of the Wankel?
    Combustion chambers could be a beat more roomy.Since four gears make like a triangle inside of casing,
    with 120 degree to each other,room between gears which is used for combustion could be regulated to
    optimize for better efficiency.You just change size of central gear to make it bigger or smaller what is better
    for you.Also it eliminates unpredictable spacing between rotor and casing which in usual Wankel could lead to
    excessive wear with time or energy looses.In new design every friction is coming through gears.But gears usually do not cause lot of friction if they are lubricated.I whish to create drawing of desing I mean but do not know how to put drawings on forum.It seems I found name for desing.This is planetary gear.
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  5. #4  
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    As I understand you the gears whould take the place of the seals that Wankle used instead of piston rings. The problem is that instead of one seal at each secton of the engine your design has 2, the intersection of the "partition" Gears with the shaft gear and the intersection with the cylinder wall. 2 places to leak for every one on a wankle.
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  6. #5  
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    I've seen a true rotary engine disign back in the 70's. It's problem was the tolerances needed. Three meshing lobes were used for the chambers and tied together with gears, but the tolerances needed to stay under 1/10,000 of an inch.
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    I've wondered if Wankel engines would have a role in hybrid vehicles--they are relatively simple, run best at high rpm where power could be generated, are light weight and pretty efficient in small sizes-- a lot of good matches for hybrids who need power. Their emissions might not be so bad compared to the size of the vehicle.

    Stanley a sketch of your idea would help.
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  8. #7  
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    Mazda has made successful use of the Wankel Rotary for years. If you've ever gotten to drive an RX-7, bad ass ride.
    Mazda Wankel engine - Wikipedia, the free encyclopedia
    jocular likes this.
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    I've wondered if Wankel engines would have a role in hybrid vehicles--they are relatively simple, run best at high rpm where power could be generated, are light weight and pretty efficient in small sizes-- a lot of good matches for hybrids who need power.
    I think that an ultimate engine for a hybrid would be an engine which doesn't contain any moving parts at all, but an energy converter which is directly converts heat or energy of gases into electric power. For example some type of compact and low temperature MHD generator. I thought before on device which could be described as a "hydrodynamic wimshurst machine" in which cloud of electric charge created by electronic emission is blown by hot gases from one electrode to another. Both electrodes could be a volumetric metallic nets. Principally I have many ideas in such fields, but dream about sponsoring.
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  10. #9  
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    What do you think about this design?
    It was used as a steam turbine engine in 19-th century.
    Would it work well as a ICE?
    rotor-motor.avi - YouTube
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  11. #10  
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    Quote Originally Posted by Stanley514 View Post
    I could imagine an engine disign and whish to know what could be
    problems with it.It is similar to Wankel engine but difference is that
    it uses few gears.It has a round combustion chamber with teeth inside
    all around it.Inside there is a few gears: a central gear which is connected
    to a shaft and designed in a way that it could rotate only in one direction.
    and two or three more gears which serve like mediators between central
    gear and inner teeth in a combustion chamber.So it is somewhat similar to
    Wankel but somehat different design.
    I agree with Harold. The issue with developing any alternative to the reciprocating IC engine is the degree to which it has now been refined, in terms of efficiency and emissions. Bear in mind that other criteria such as reliability, smoothness and noise level have been optimised so much that any improvement in these areas is not likely to be compelling.

    If you want to interest anybody in an alternative, you need to come forward with reasons as to why your new design would be expected to be superior, on both of these first two criteria.

    Do you have reasons to expect this?
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  12. #11  
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    Old thread. At least some sort of picture...(finally)

    Wankels are still being made for applications that take advantage of their benefits such a light weight and knock resistance to low octane fuels.
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    Quote Originally Posted by exchemist View Post
    I agree with Harold. The issue with developing any alternative to the reciprocating IC engine is the degree to which it has now been refined, in terms of efficiency and emissions. Bear in mind that other criteria such as reliability, smoothness and noise level have been optimised so much that any improvement in these areas is not likely to be compelling.
    That's path dependency, and is often not a good thing in terms of innovation. Apply the same improvements to, say, a free-piston engine or a wave disk engine and you might see even greater efficiencies, flexibilities, durabilities etc. The first version of any of the above will not match a modern IC recip engine because of the decades of tweaking that went into the recip engine. That, however, should not discourage people from developing new engines that, in the long run, could be even better than a recip engine.
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by exchemist View Post
    I agree with Harold. The issue with developing any alternative to the reciprocating IC engine is the degree to which it has now been refined, in terms of efficiency and emissions. Bear in mind that other criteria such as reliability, smoothness and noise level have been optimised so much that any improvement in these areas is not likely to be compelling.
    That's path dependency, and is often not a good thing in terms of innovation. Apply the same improvements to, say, a free-piston engine or a wave disk engine and you might see even greater efficiencies, flexibilities, durabilities etc. The first version of any of the above will not match a modern IC recip engine because of the decades of tweaking that went into the recip engine. That, however, should not discourage people from developing new engines that, in the long run, could be even better than a recip engine.
    Sure, that's what I meant. You need to have a reason why it could be better in some respect, don't you?
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  15. #14  
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    Quote Originally Posted by exchemist View Post
    Sure, that's what I meant. You need to have a reason why it could be better in some respect, don't you?
    Definitely, and such engines do have some advantages over conventional engines. It would take years of development to get them to the point where they were useful though.
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  16. #15  
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    Quote Originally Posted by exchemist View Post
    Sure, that's what I meant. You need to have a reason why it could be better in some respect, don't you?
    Wankels already have advantages in power to weight, reliability and low vibration.

    They failed to be the engine of choice in auto because they tend to be dirty like all 2 cycles which increasingly couldn't meet environmental standards and their torque and power curves also require completely different transmissions for best efficiency.
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  17. #16  
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    Quote Originally Posted by Lynx_Fox View Post
    Quote Originally Posted by exchemist View Post
    Sure, that's what I meant. You need to have a reason why it could be better in some respect, don't you?
    Wankels already have advantages in power to weight, reliability and low vibration.

    They failed to be the engine of choice in auto because they tend to be dirty like all 2 cycles which increasingly couldn't meet environmental standards and their torque and power curves also require completely different transmissions for best efficiency.
    I think it was poor emissions (crevice volume etc) and poor reliability of the the rotor tip seals that did for them. Te crevice volume issue is quite important with combustion chambers that are not rectilinear.
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  18. #17  
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    Split cycle Wankel engine proposed.
    Halfbakery: Split Cycle Wankel Engine

    Though I do not see what would be advantage of such engine over piston reciprocation engine.
    Two rotors will make it pretty complicated and expensive.
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  19. #18  
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    There is this: Libralato Engines - Technology

    I don't know how well it works in practice but it may be that the requirements for a hybrid car make it more practical.
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    What would you think about advantages and disadvantages of screw conveyor - type engine?
    I think advantages could be elimination of reciprocation motion and crankshaft. Good thing for an electric generator.

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  21. #20  
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    Quote Originally Posted by Stanley514 View Post
    What would you think about advantages and disadvantages of screw conveyor - type engine?
    I think advantages could be elimination of reciprocation motion and crankshaft. Good thing for an electric generator.

    How does that have any advantage over conventional generators and turbines?
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  22. #21  
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    Quote Originally Posted by Stanley514 View Post
    What would you think about advantages and disadvantages of screw conveyor - type engine?
    I think advantages could be elimination of reciprocation motion and crankshaft. Good thing for an electric generator.

    An Archimedean screw - interesting. I suppose one difference from a turbine is that you have a positive seal, preventing leakage of the working fluid through the mechanism. Perhaps this would be an advantage for a low pressure, slow-moving, working fluid, or for fluids from fuels that can't be burnt in a reciprocating engine.

    But as Billvon says, conventional turbines would be the alternative. In combined cycle mode these have efficiencies of over 60% nowadays - but that does require a non-aggressive liquid or gaseous fuel for the gas turbine stage, so has its limitations. (You can't burn heavy fuel oil in one of these, for example).
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  23. #22  
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    But as Billvon says, conventional turbines would be the alternative. In combined cycle mode these have efficiencies of over 60% nowadays - but that does require a non-aggressive liquid or gaseous fuel for the gas turbine stage, so has its limitations.
    I think it could be an alternative to reciprocating generator similar to one in a Chevy Volt - a serial hybrid.
    Chevrolet Volt - Wikipedia, the free encyclopedia
    Gas turbines are not very efficient at small sizes and expensive. A screw conveyor would be simpler than reciprocating engine, having smaller amount of moving parts. In the same time it may lack problems associated with free-piston generator such as noise, vibration, and sophisticated controls. It doesn't need crankshaft and hence smaller friction and looses.
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  24. #23  
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    Quote Originally Posted by Stanley514 View Post
    But as Billvon says, conventional turbines would be the alternative. In combined cycle mode these have efficiencies of over 60% nowadays - but that does require a non-aggressive liquid or gaseous fuel for the gas turbine stage, so has its limitations.
    I think it could be an alternative to reciprocating generator similar to one in a Chevy Volt - a serial hybrid.
    Chevrolet Volt - Wikipedia, the free encyclopedia
    Gas turbines are not very efficient at small sizes and expensive. A screw conveyor would be simpler than reciprocating engine, having smaller amount of moving parts. In the same time it may lack problems associated with free-piston generator such as noise, vibration, and sophisticated controls. It doesn't need crankshaft and hence smaller friction and looses.
    If it were an improvement on the conventional IC engine, why would it apply particularly to a generator application? But in any case a great deal of work is needed to turn this operating principle, which is all you have at the moment, into an engine. Where and how would the fuel be burnt, how would the air supply and fuel metering be arranged, at what speed and at what pressures would the screw operate, where and how would expansion of the working fluid occur, would how would the exhaust be configured to allow the shaft to transmit power to the load, how would the screw be sealed, and so on. At the moment none of this is apparent.
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