Completely custom rotary engine idea
03-15-2009, 10:08 PM
#1
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Hello all. I believe this is my first post here, but have had this idea for quite some time now. The premise would be I guess basically a V-rotary were there are 2 combustion chambers and 2 intake and exhaust ports per rotor. This means five rotations of the eccentric shaft for every one revolution of a rotor. Additionally, I was thinking because the combustion cycle is a bit shorter if the rotor was thicker and multiple sparks were used it could be a more complete burn leading to better emissions. Also, I was thinking in order to increase effeciency of the motor one side could be shut off at low speeds, much like displacement on demand. I got this idea after talking to an engine builder about a 4 rotor and deactivating rotors under low loads which he had played with but didnt work because there would be lubrication issues in the non firing rotors, however in a setup like this, as long as one spark per rotor is active then the rotor should be ok. Depending on what you guys think of this idea it may be going in a car I am currently designing. Let me know what you think of this idea. Check out the video below.. hopefully it works. I hope this wasnt all too much information right away, I have a few other ideas to incorporate if you guys want to talk about it.
[attachment=45494:Movie_1.wmv]
[attachment=45494:Movie_1.wmv]
03-15-2009, 10:10 PM
#2
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Oh, also, I have looked around but couldnt find anything on it. If a thread or discussion of a motor of this type exists anywhere could someone please forward me there? Even if it is just someone being told they are crazy for thinking they can build something like this. Thanks guys... please dont flame me too badly.
03-15-2009, 10:30 PM
#3
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It's called a compound Wankel which Moller (those loons that are trying to make skycars) and Rolls-Royce back in the 70s both have created. The only difference is you're talking about it all happening in one housing whereas the Moller and Rolls engines do it in two classically-shaped Wankel housings in series. The shape you're talking about appears in the original copy of "Rotary Engine" though. The problem is that the 5 sided rotor has to be very convex versus the concave shape of the usual rotors. This is for clearance reasons, but also means that the compression likely isn't high enough for combustion without a turbo (or two).
03-16-2009, 05:45 PM
#4
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Wow, thank you for the quick response. Do you know where I can find any information on the compound wankel? I have searched a bit for it today at work, but everything seems a bit hush hush on the details, or really even the generics of the motor. Sorry to sound completely stupid but what is the original copy of Rotary Engine? Is this a publication of sorts? I do agree on the the radius of the rotor faces had to be increased drastically to make the clearance work. I am not sure of the exact numbers right now. So in this logic, the higher the eccentricity the higher the compression and the higher the efficiency? I was under the impression of lowering the eccentricity would increase efficiency. Thanks again for your help.
Originally Posted by Nateb123' post='918415' date='Mar 15 2009, 07:30 PM
It's called a compound Wankel which Moller (those loons that are trying to make skycars) and Rolls-Royce back in the 70s both have created. The only difference is you're talking about it all happening in one housing whereas the Moller and Rolls engines do it in two classically-shaped Wankel housings in series. The shape you're talking about appears in the original copy of "Rotary Engine" though. The problem is that the 5 sided rotor has to be very convex versus the concave shape of the usual rotors. This is for clearance reasons, but also means that the compression likely isn't high enough for combustion without a turbo (or two).
03-19-2009, 06:45 PM
#5
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Originally Posted by drxlcarfreak' post='918412' date='Mar 15 2009, 08:08 PM
Hello all. I believe this is my first post here, but have had this idea for quite some time now. The premise would be I guess basically a V-rotary were there are 2 combustion chambers and 2 intake and exhaust ports per rotor. This means five rotations of the eccentric shaft for every one revolution of a rotor. Additionally, I was thinking because the combustion cycle is a bit shorter if the rotor was thicker and multiple sparks were used it could be a more complete burn leading to better emissions. Also, I was thinking in order to increase effeciency of the motor one side could be shut off at low speeds, much like displacement on demand. I got this idea after talking to an engine builder about a 4 rotor and deactivating rotors under low loads which he had played with but didnt work because there would be lubrication issues in the non firing rotors, however in a setup like this, as long as one spark per rotor is active then the rotor should be ok. Depending on what you guys think of this idea it may be going in a car I am currently designing. Let me know what you think of this idea. Check out the video below.. hopefully it works. I hope this wasnt all too much information right away, I have a few other ideas to incorporate if you guys want to talk about it.
[attachment=45494:Movie_1.wmv]
[attachment=45494:Movie_1.wmv]
Look here for Kenici Yamamoto's books. http://foxed.ca/foxed/index.php?page=rx7manual bottom of the page.
also dozens of Mazda data for free........................
Lynn E. Hanover
Download for free. Hyperlink is from Paul Lamars web site.
03-20-2009, 01:39 PM
#7
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Originally Posted by drxlcarfreak' post='918466' date='Mar 16 2009, 03:45 PM
...I do agree on the the radius of the rotor faces had to be increased drastically to make the clearance work. I am not sure of the exact numbers right now. So in this logic, the higher the eccentricity the higher the compression and the higher the efficiency? I was under the impression of lowering the eccentricity would increase efficiency. Thanks again for your help.
That may be the case that a lower e would increase efficiency for an air pump. I honestly am not acquainted with the engine well enough to know for sure, though your impression seems correct. However an engine is clearly more complex and as eccentricity goes to zero, so does the change in volume during a combustion cycle. So a hit in efficiency is necessary to make power, but power comes from a high surface area to volume ratio of the working chamber. That means MORE eccentricity. So why don't we up eccentricity? After all, that's what Mazda has done with the 16X and torque is up significantly over 13b designs.
The real problem as I know it isn't extracting efficiency from the rotary engine, but remaining efficient while gaining torque and power. There are a few ways to do this. Traditionally, higher revs are used to gain power and shorter gearing is used to provide the needed torque. Eccentricity is another way to increase low end torque while maintaining high revving capability. However the eccentricity has a physical limit: the rotor face hitting the housing. This limit reduces the eccentricity which is possible and therefore the torque (as a result of efficiency, compression, etc.). As you gain more rotor faces, you get less wiggle room in the trochoid's shape. This means the surface area to volume ratio grows and torque to be had is greatly minimized, which causes a loss of torque.
Some other things to consider is that fuel will stick more to the housing and rotor face with so much surface area to volume. This means more fuel wasted and is a big reason rotaries thus far aren't very efficient. Also, with more chambers the rotor is going to be much bigger and the chambers will be smaller than the usual wankel of comparable size. That means scaling up your engine to gain necessary torque and power. Plus there's more weight from that big fat rotor in the middle over the usual triangle. However, there is promise as the e shaft spins once every fifth of a rotor revolution, which means the whole engine takes on less stress. Overall, this leads me to think it may be a good engine for a bigger vehicle, but not a sportscar engine.
03-21-2009, 06:26 PM
#8
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Originally Posted by drxlcarfreak' post='918413' date='Mar 15 2009, 08:10 PM
Oh, also, I have looked around but couldnt find anything on it. If a thread or discussion of a motor of this type exists anywhere could someone please forward me there? Even if it is just someone being told they are crazy for thinking they can build something like this. Thanks guys... please dont flame me too badly.
There is (almost) nothing new under the sun. Wankel didn't invent the engine. He stole the shapes from patent drawings owned by a mechanical engineer who worked for a truck manufacturer. The design was for a brake air compressor.
He was looking for pure rotary motion. NSU signed on with Felix and built two of his designs. The outer (rotor housing) rotated at 2/3 rotor speed. The plugs were inside the rotors. No way in hell was it viable as a production engine.
NSU engineers and techs came up with the fixed housing engine you have today. Felix got pissed and left.
When NSU tried to patent the design, they found the true owner of the patent. DUH.......He gifted the patent giving away millions.
Check out Paul Lamar's web page at: http://www.rotaryeng.net/
Check the news group archives for various iterations on the rotary. Today and yesterday there were some pictures of the various shapes proposed.
Lynn E. Hanover
03-23-2009, 10:54 PM
#9
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From what I am reading increasing the eccentricity would increase compression, would could increase fuel effeciency as well then. Hmm, reading through this, it sounds as though you are correct unless we make the overall rotor quite small in comparison to a 13B. Say a 5 sided rotor has half the displacement of a typical 3 sided rotor. Although this would increase weight as more rotors are needed to keep necessary power. I do believe you are right, this is an engine idea more likely for a larger car than a sports car... :-(
I thought I was on to something!
I thought I was on to something!
Originally Posted by Nateb123' post='918749' date='Mar 20 2009, 11:39 AM
That may be the case that a lower e would increase efficiency for an air pump. I honestly am not acquainted with the engine well enough to know for sure, though your impression seems correct. However an engine is clearly more complex and as eccentricity goes to zero, so does the change in volume during a combustion cycle. So a hit in efficiency is necessary to make power, but power comes from a high surface area to volume ratio of the working chamber. That means MORE eccentricity. So why don't we up eccentricity? After all, that's what Mazda has done with the 16X and torque is up significantly over 13b designs.
The real problem as I know it isn't extracting efficiency from the rotary engine, but remaining efficient while gaining torque and power. There are a few ways to do this. Traditionally, higher revs are used to gain power and shorter gearing is used to provide the needed torque. Eccentricity is another way to increase low end torque while maintaining high revving capability. However the eccentricity has a physical limit: the rotor face hitting the housing. This limit reduces the eccentricity which is possible and therefore the torque (as a result of efficiency, compression, etc.). As you gain more rotor faces, you get less wiggle room in the trochoid's shape. This means the surface area to volume ratio grows and torque to be had is greatly minimized, which causes a loss of torque.
Some other things to consider is that fuel will stick more to the housing and rotor face with so much surface area to volume. This means more fuel wasted and is a big reason rotaries thus far aren't very efficient. Also, with more chambers the rotor is going to be much bigger and the chambers will be smaller than the usual wankel of comparable size. That means scaling up your engine to gain necessary torque and power. Plus there's more weight from that big fat rotor in the middle over the usual triangle. However, there is promise as the e shaft spins once every fifth of a rotor revolution, which means the whole engine takes on less stress. Overall, this leads me to think it may be a good engine for a bigger vehicle, but not a sportscar engine.
The real problem as I know it isn't extracting efficiency from the rotary engine, but remaining efficient while gaining torque and power. There are a few ways to do this. Traditionally, higher revs are used to gain power and shorter gearing is used to provide the needed torque. Eccentricity is another way to increase low end torque while maintaining high revving capability. However the eccentricity has a physical limit: the rotor face hitting the housing. This limit reduces the eccentricity which is possible and therefore the torque (as a result of efficiency, compression, etc.). As you gain more rotor faces, you get less wiggle room in the trochoid's shape. This means the surface area to volume ratio grows and torque to be had is greatly minimized, which causes a loss of torque.
Some other things to consider is that fuel will stick more to the housing and rotor face with so much surface area to volume. This means more fuel wasted and is a big reason rotaries thus far aren't very efficient. Also, with more chambers the rotor is going to be much bigger and the chambers will be smaller than the usual wankel of comparable size. That means scaling up your engine to gain necessary torque and power. Plus there's more weight from that big fat rotor in the middle over the usual triangle. However, there is promise as the e shaft spins once every fifth of a rotor revolution, which means the whole engine takes on less stress. Overall, this leads me to think it may be a good engine for a bigger vehicle, but not a sportscar engine.
03-23-2009, 10:55 PM
#10
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Join Date: Apr 2008
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WOW, that is a TON of information, thank you!
Originally Posted by Lynn E. Hanover' post='918698' date='Mar 19 2009, 04:45 PM
Look here for Kenici Yamamoto's books. http://foxed.ca/foxed/index.php?page=rx7manual bottom of the page.
also dozens of Mazda data for free........................
Lynn E. Hanover
Download for free. Hyperlink is from Paul Lamars web site.
also dozens of Mazda data for free........................
Lynn E. Hanover
Download for free. Hyperlink is from Paul Lamars web site.
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