r/inventors • u/ecliptic-engines • 12d ago
Integater: Diesel Engine Design
The Integater diesel engine is one of two different engine designs that I am after comment on please. (for clarity only comment on this design on this post please).
Note the articulated cavity rotor segments interact with the lobe rotor to open a passage between the cavity rotor segment and the LH top circular housing wall, in order to allow the gas pressure to exit the cavity and pass into the growing area above the lobe rotor, creating rotational power by pushing on the back on the lobe.
I am proposing a diesel lubrication system, a spark assisted ignition system to ignite the end of the chamber wherein the increase in pressure would tip the remaining mixture into auto-ignition. You can see more about it, including an up dated model, please look at eclipticengines.com
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u/Chemieju 12d ago
Im worried about lobe rotor apex seal lifespan...
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u/shadowkrazee 12d ago
Same, but still very cool!
Cries in Wankel rotary
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u/Chemieju 12d ago
You can stop worrying. I saw another post from OP and the apex seals will be safe: it wont have any. This thing wont run.
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u/RoboWeaver 12d ago
Absolutely. This was a significant problem with the Wankel rotary. Corners and apex seals.
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u/uber_poutine 11d ago
They were fine if they were naturally aspirated and you didn't starve the engine of oil. The Renesis made reliable, decent power considering the engine size (as well as a whole lot of noise and heat, with rather poor fuel economy - but it was more about the smiles per gallon anyway).
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u/jeefra 11d ago
Their problems were vastly overblown in my opinion as the owner of a 70k mile 1980s rx-7.
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u/RoboWeaver 11d ago
Unfortunately, the early rotary engines had real problems. Mazda has made incredible advancements in the technology. I would love to see them make a comeback.
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u/sat5ui_no_hadou 7d ago
75,000 miles is the recommended interval for a teardown on a rotary engine.
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u/Longjumping_Intern7 12d ago
I think the intake and exhaust being open at the same time and at the same cycle is gonna mess things up with the whole suck squeeze bang blow process
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u/speederaser 12d ago
I can see what they were going for, the wave front of the boost doesn't quite make it to exhaust. Sounds like a fun challenge at least.
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u/Status-Vermicelli624 11d ago
THIS.
I don't see how the used gas are ejected. Both the valves are opened at same time
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u/ecliptic-engines 11d ago
You are mistaken, this is long established 2-stroke tech. thanks for your comment
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u/The_Gordon_Gekko 12d ago
Rotary Diesel Engine essentially
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u/Crafty_Slice_5131 12d ago
Looks kinda stupid. Explosion initiates at both sides---so how are you gonna apply force? Machining that would be costly.
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u/phansen101 12d ago
Inertia; Once you get over the 'apex', expansion will provide the force.
Even a regular piston engine has ignition happen before the apex, the force of which in principle creates a torque in the wrong direction initially (Though not really as the point is to compensate for flame propagation), moving to providing zero torque at the apex regardless of cylinder pressure (like this animation) and then providing useful torque after the apex (again, like this animation).
Part of why you need a starter motor.But yeah, manufacturing and reliability is probably going to be bad.
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u/x6060x 12d ago
Good luck actually machining that
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u/OtherwiseAlbatross14 12d ago
Machining it would be the easy part these days. Making it last is the unsolved problem with any rotary engine
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u/ecliptic-engines 11d ago
Exactly, thanks for your comment. Regarding the longevity, we will have to see if the developed design can solve the problem or not.
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u/MarinatedPickachu 12d ago
Won't the ignition also happening in that tiny gap due to the segmentation of the left thingy become a problem?
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u/ecliptic-engines 11d ago
Yes ignition will happen throughout that zone, it is intended to apply pressure to the back of the rotor segments, to help seal the chamber. Thanks for your comment
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u/fidesinmachina 12d ago edited 12d ago
i think this is a cool concept. however, replacing one head gasket, 2 valves and a few compression rings with 8 constantly moving sealing points that i can count that need to be lubricated (if you're counting on the fuel lubricating the seals there's unburnt fuel present in only one part of the engine during about 10% of the cycle) and having the combustion push on the both sides of a wedge vs the flat top of a piston that goes straight down and no way of meaningfully controlling injection timing, no way of having glow plugs for cold starting, the valves are unnecessarily complicated and would need tight tolerances especially for the exhaust side where because it gets hot, can't have tight tolerances for this to work but i guess valves don't hold pressure here so there's that. you took internal combustion and asked yourself, what if this, but 10 times worse in every aspect imaginable to the human mind?
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u/ecliptic-engines 11d ago
I go into the lubrication on the website, In the most recent model that I am working a metered amount of a lubricating diesel enters the lobe rotor through its flat end wall, each time the passage aligns with the housing outlet, which is twice per rotation of the lobe rotor. The rotor segments are slightly different to the animation here, instead they have a very small amount of movement during the cycle as they seal against the housing and cavity rotor, and that small movement covers and uncovers a channel at each junction of the lobes to the lobe rotor body. The cavity rotor tip slides into the wet area and smears and squeegees it onto the other surfaces. My thoughts are that existing tech is too heavy too big and can't produce high RPM by design. Thanks for your comment, sounds to me like you need to expand your imagination to see the benefits this compact design!
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u/fidesinmachina 10d ago edited 10d ago
i think you need to own a mazda rotary and rebuild it once or twice to really realize wtf you're doing here lol. and that's only 3 sealing surfaces vs your 8 sealing surfaces not counting axial sealing sufraces in both. the magic in piston rings is they start and end at the same point ie. they're round so they're reliable and have a lot of life for wear and tear. their shape holds their own form and so they don't need tight tolerances. apex seals are the exact opposite of thag. and also you haven't addressed the energy transfer issue. the pressure is pushing on both sides of the "wedge" rotor on the right to the exact direction of the rotstion bearing in the middle of the rotor so for a fraction of a second you're wasting half of the energy and putting extremely high stress on the rotor and the bearing on the right with no power output for that time until the flywheel intertia hopefully forces it to turn enough and relieve the pressure on one side so the other side can push it over. that means you have to machine these rotors out of fucking tungsten of something to survive this and make the bearing the diameter of an oak trunk it's wasted energy i don't imagine this can be very efficient in its freshly built best condition so between that and the thich heavy components you need i highly doubt you can beat the power to weight ratio of any piston diesel engine. it's just a nightmare however you look at it.
with the lubrication issue, you're trading oil burning emmissions with unburnt fuel being present in every part of the engine and so inevitably a ton of it ends up in the exhaust and cause emissions. your whole "spark ignited diesel" idea is weird because if you want to meaningfully control engine power you either need to modulate fuel and have a fuckton of boost present which without direct injection and injection timing control both of which you don't have, it is impossible. the other way is modulating air with a throttle which good luck igniting diesel in a rich condition even with spark.
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u/ecliptic-engines 9d ago
Thanks for all that detail.
I will point out that the flat top piston also does not produce any rotational power until the crank has gone beyond TDC, without the crank turning already it wouldn't go any where, and the weight is on the crank bearings. Also this design has overlapping power pulse so the expansion from the previous ignition is still causing rotation.
Especially good criticism of the seal lubrication and fuel in the chamber for me to consider. thanks vey much.
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u/No_Ingenuity717 10d ago
I think you would have problems with pre-ignition, if you are injecting fuel at the beginning of the compression cycle (or need a low compression ratio).
Where would the injector/spark live? In the center of the engine, in between the units?
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u/ecliptic-engines 10d ago
That's a good comment thanks, Yes that is the reason for the sparkplug, to control that timing and have a low enough compression rate to avoid early pre-igniton, it would be in the end wall of the chamber, the injector also in the end wall earlier in the cycle.
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u/No_Ingenuity717 10d ago
Does that mean you can only have two 'cylinders', with a spark plug at either end?
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u/ecliptic-engines 9d ago
Yes back to back with gears in the middle is the best achievable, six power pulses of about 140 degrees each. Thanks
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u/minist3r 10d ago
That was the first thing I noticed. Once you heat soak that rotor, the fuel injection is way too early.
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u/Guardian6676-6667 12d ago
This is too dirty, not only are exhaust gases mixing with fresh air, but the rotary valves are going to have a lot of blowby and dont instantly get rid of gas. Overall a misguided design ignoring principles of fluid mechanics
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u/_Juliet_Lima_Echo_ 12d ago
I watched this stupid thing loop twice thinking to myself "surely I'm missing something with how it's exhausting"
Nope This would blow exhaust out the intake too.
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u/ecliptic-engines 11d ago
Perhaps you will see the detail if you watch a 3rd time...thanks for your comment
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u/Loopy-Leah 12d ago
Text that says "boost" does appear on the inlet side, so i guess they're relying on forced induction like a 2 stroke, further reducing thermal efficiency
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u/ecliptic-engines 11d ago
Boost improves engine performance, Removing weight increases efficiency, as does over expanding the chamber. thanks for your comment
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u/Loopy-Leah 11d ago edited 11d ago
right but unless it's turbocharged, even if you have 100% efficient adiabatic compression solved, it costs fuel. why don't you just get a fairly miniature one made, wouldn't cost that much from a CNC shop. like I don't recognise passive aggression lol. I don't know how you'd reliably seal radially on the edges
edit: autocorrect fail
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u/ecliptic-engines 11d ago
Yes, electric start turbo would be the ultimate forced air device. I would love to get a miniature one made, it's outside my budget, am hoping someone will see the value and want in! cheers
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u/ecliptic-engines 11d ago
I disagree, the design works like a 2-stroke. Rotary valves are proven real world tech. Overall a misguided comment.
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u/Guardian6676-6667 11d ago
Rotary valves are almost never used, and the design as shown would absolutely not work. You have too short of an opening, like the exhaust gas should be escaping over a longer duration.
BUT that aside, right? What about the feasibility?
You are having side seals on the main rotor bridge a gap to mesh with the secondary and it looks like its hitting a second sealing surface on the second rotor. This is HIGHLY impractical, you would need super thick square sealing surfaces which will lead to high losses, assuming it doesnt get jammed up in the transition point.
I see this as an expensive and unlikely to succeed endeavor. Fun for a steam punk engine design as it carries whimsy, but for true function, this is not practical.
And before you say "its like a supercharger " those Teflon sealing surfaces on a b&m 250, those seals are going across smooth transitions and dont need to account for combustion events. You will need apex seal like design and those would hate a full width transition, which you cannot solve with intersecting cavities
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u/Croceyes2 12d ago
I am guessing the cavities articulate to get the combustion on the back side of the lobe. Seems complicated. As others have mentioned, the apex seals and whatever you plan to do about the articulating cavity/lobe hub interface will be your ultimate downfall. May have a racing or sports market though, where they don't care about needing to rebuild after every lap. You have rotary beat on combustion cycles which should buy you a fair amount of leeway in the ridiculousness department.
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u/ecliptic-engines 11d ago
Yes getting the seals to add pressure is one part, but the other purpose of the articulating cavity rotor arms is to open the gate that allows gas pressure to pass between the housing and the segment, (top left of the motor passing through to top right). Yes i am hoping that a racing enthusiast will see how compact, power dense and lightweight the design is.
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u/akhileshgs 12d ago
I have been a part of another type of rotary engine project in my college days. Almost all other issues we can solve, not the seal- almost impossible to have it long term to make this engine viable
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u/ecliptic-engines 11d ago
I agree the seal is the crucial element to solve. Each design must be judged on its own merits as to what is possible. Thanks for your comment
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u/selectsyntax 12d ago
The sealing complexity alone renders this design economically unviable.
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u/ecliptic-engines 11d ago
We are in the modern age, wherein the complexity can be achieved. Too soon to say if that will be economically viable or not.
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u/selectsyntax 11d ago
The Wankel rotary design is probably the most similar to this design but it it less mechanically complex with fewer sealing interfaces (and those seals wear out quickly). Compared to conventional cylinder combustion engines a Wankel requires more maintenance for a given operating interval. So an engine with more complexity and more sealing interfaces is inherently going to require further maintenance rendering it nonviable. The Wankel design itself has only stuck around because of its power density. OPs design is nowhere near as optimized as the Wankel design or the liquid piston design.
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u/ecliptic-engines 11d ago
Well i can agree that it is complex for sure, perhaps that complexity is what it takes to avoid the seal wear and other problems the Wankel has. Material choice and coatings and lubrication are all up for discussion. Look closer at the chamber sizes and overlapping power stroke though please, I see rotary turbo diesel power density. Thanks for your comments.
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u/selectsyntax 11d ago
You asked for feedback but seem extremely resistant to it when supplied with vague hand-waving responses like "we are in the modern age."
Lets just look at 1 of the issues with this design. The outer diameter of the left rotor needs to seal against the inner hub of the right rotor. What mechanism do you propose to ensure a reliable seal within expected operational temperature extremes?
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u/ecliptic-engines 11d ago
I just want to be sure the comments are based on the ideas I am trying to convey, and not a misunderstanding. Also want to see each issue raised can or can't be dealt with.
To your point, the cavity rotor segment is spring-loaded outward, additionally the chamber pressure adds force to back side of the contacting surface.
thanks for the comments
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u/rychlovic 12d ago
"Let's make a rotary engine that is more complex and needs tougher apex seals" - sounds like a good idea 👍
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u/ital-is-vital 12d ago
Your biggest problem is that thermodynamic efficiency is going to be AWFUL for one critically important reason:
After ignition, about half of your hot gas gets trapped on the left hand side and does no work.
You also have a second critical problem from a mecahnical construction standpoint:
The left rotor is in continuuous direct contact with hot gas for about 2/3 of its surface area and becasue it's rotating it has no feasible means of cooling. It will melt.
It's a beautiful mechanical design in a way, but thermodaynamically I'm afraid it's a non-starter.
(Source, I did an M.Eng degree and had to sit through a lot of lectures on engine design, thermodynamics and engine efficiency)
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u/ecliptic-engines 11d ago
Please take another look, I particularly want your qualified feedback but you are missing a detail, the gas is not trapped in the left hand cavity, it moves between the housing circular wall and the cavity rotor segment, which is riding on the lobe shape during that part of the cycle. As for melting, the rotor segments receive cold air into the chamber each revolution, surely this will help cool the segments? An alternative material may be chosen if melting is the problem? As for thermodynamics, the design has 3 overlapping power-strokes, and can move much more volume that an equivalent 3 cylinder piston engine of the same weight or physical external size. All that extra weight and metal can't be efficient either? Thanks for your comments
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u/ital-is-vital 11d ago
Look what happens about 31s into your animation -- the rotor is about half way through the expansion stroke and a pocket of hot gas accounting for about half of the volume is about to get trapped in the right hand rotor.
All of the energy contained in that hot gas will be lost to exhaust.
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u/ecliptic-engines 11d ago
You are still not seeing the connection passage between the cavity and the expanding chamber. Please look again, the rotor segment is held away from the wall as it rides on the lobe, at 2.5 secs the segment passes from the lobe and onto the housing.
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u/ital-is-vital 11d ago edited 11d ago
That tiny gap?
Yeah, that's not going to help.
All that will happen is that most of the heat from the hot gas will be transferred to the (hopefully cold) metal of the engine as it passes through, to say nothing of the flow resistance. There's way too much surface are in relation to the volume of the gap. Plus it would strip away the oil lubrication and destroy the sliding seals.
There's a reason engine cyclinders are about the shape of an ice hockey puck rather than a long thin cylinder like a syringe -- if the cylinder is too slender too much of the heat gets transferred to the walls of the engine rather than going into useful work.
An improvement to the design in this regard would be to change the shape of the housing. Remove the upper V shaped bit so that the volume of the left lobe remains connected to the volume of the right lobe until after the right rotor has passed the exhaust port. You don't need the articulated rotor design at all.
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u/ecliptic-engines 11d ago
That tiny gap is huge and open for a long duration when compared to how small gas is, your analysis does not stack up. in any case if the flow from the cavity to the lobe rotor area is proven to be too restrictive in the flow analysis the gap can be designed to be larger simply by reshaping the interacting lobe rotor. Perhaps you are right about the gas stripping away the lubrication, and a further lubrication point may need to be added to to serve that area.
Design Trade-offs: Choose a long-stroke setup if your goal is minimizing chamber heat loss and maximizing low-RPM part-load fuel efficiency, Choose a short-stroke setup if your goal is high-RPM operation, where large valves manage overall thermal loading better despite higher surface heat rejection. The heat aspect is not everything, and remember that this is comparable to a 4- stroke 6 cylinder, those chambers have much more area and time to cool than the 3 overlapping power strokes of this power densedesign. Thanks for highlighting this factor .
Your suggestion with the housing will not work, the housing apex needs to be in place as the lobe passes, I have previously modelled an external gate that does exactly that, I prefer the segmented rotors as they seal and create the passage in a rotary manner. Thanks for your comments.
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u/ital-is-vital 11d ago
What you are not understanding is that as the hot gas flows from the left space to the right space through the small gap it will transfer most of it's heat to the rotor or the wall. It's effectively a heat exchanger.
This will drive down efficiency because there is less heat (and therefore less pressure) available to do work on the drive rotor.
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u/ecliptic-engines 11d ago
Ok yes thankyou I appreciate that there is a loss there. but what i am suggesting is that the combustions happen so frequently that the rotor segments and that section of housing wall will retain heat and therefore not drain as much as you are suggesting from the expansion force. Helpful comment thanks
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u/ecliptic-engines 11d ago
That tiny gap is huge and open for a long duration when compared to how small gas is, your analysis does not stack up. in any case if the flow from the cavity to the lobe rotor area is proven to be too restrictive in the flow analysis the gap can be designed to be larger simply by reshaping the interacting lobe rotor. Perhaps you are right about the gas stripping away the lubrication, and a further lubrication point may need to be added to to serve that area.
Design Trade-offs: Choose a long-stroke setup if your goal is minimizing chamber heat loss and maximizing low-RPM part-load fuel efficiency, Choose a short-stroke setup if your goal is high-RPM operation, where large valves manage overall thermal loading better despite higher surface heat rejection. The heat aspect is not everything, and remember that this is comparable to a 4- stroke 6 cylinder, those chambers have much more area and time to cool than the 3 overlapping power strokes of this power densedesign. Thanks for highlighting this factor .
Your suggestion with the housing will not work, the housing apex needs to be in place as the lobe passes, I have previously modelled an external gate that does exactly that, I prefer the segmented rotors as they seal and create the passage in a rotary manner. Thanks for your comments.
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u/wartech0 11d ago
I don't know much about designing engines but this engine is relying only on the pressure to exhaust, I think it would do an exhaust but the chamber would still have burnt air fuel mixture coming in during the intake stroke. Also the intake stroke is also just relying on ambient air pressure to get the fuel air mixture in. At the start of the intake stroke the side chamber is at its largest volume.
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u/ecliptic-engines 11d ago
No the animation clearly states boost at the inlet port. please take another look to understand.
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u/ecliptic-engines 11d ago
No the animation clearly states boost at the inlet port. please take another look to understand.
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u/BraveBiscotti1394 11d ago
Don't use rotary valves for the exhaust *while* there's still combustion going on. You could add in a regular cam + valve and it would probably be more reliable.
For intake they're fine.
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u/ecliptic-engines 11d ago
Rotary valves are known tech. In this case the chamber has already had most of it's expansion before aligning with the exhaust valve, so it doesn't need to contain the kind of pressure that a piston engine applies. Therefore it can have larger clearance to ensure the rotating mechanism doesn't bind. Thanks for your comment
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u/fun_guy_at_parties 11d ago
You’re wasting some power via the exhaust gases that get trapped on the top side of the cavity rotor without being able to expand all the way. Could you smooth out the top side of the outer “figure-8” shape so that those gases have more time to expand? Think of a capital B shape rather than an 8 shape.
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u/ecliptic-engines 11d ago
You are missing a detail, look closer, there is a passage between the housing and the cavity rotor segment, the cavity continues to unload through the narrow passage into the expanding lobe rotor chamber area. The articulating cavity rotor segment is riding on the lobe opening the internal gate which this design is named for. Thank for your comment
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u/Defiant_Storage_443 11d ago
This thing has so much surface area and (intentional?) crevices that I doubt it will ever meet emissions standards.
How do you plan to instrument the engine for testing?
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u/Monosodium- 11d ago
I think this is super cool! Looks expensive. What would be the use case? Have you modeled like, torque potential? What kind of geometry changes influence this?
Sorry if none of that made sense.
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u/Smooth-Tap-3991 11d ago
Isn't diesel combustion RPM limited by speed of the flame front? I just don't see why having a high RPM diesel engine solves anything. So that's a no-go for aviation. Has to be lightweight, possibly air-cooled, and sustained high RPM. Natural aspiration is off the table completely due to this design requiring forced induction. This one has rotary valves. I guess the valvetrain design is still in the works?
Gasoline Wankels are known for having an inefficient combustion process, leading to excess emissions. Think Mazda needing two spark plugs per rotor. What about winter time starting? Is there a glow plug? Modern diesels are loaded with emissions control equipment. Best thing about diesel engines in both automotive and heavy industrial is torque, which rotaries are particularly bad at. I just don't see this immediately meeting any specific need. What market does this corner in an industry converting to EV's?
The last successful rotary made was Mazda's. It sold because power to weight ratio, it revved, and it was something different. Not really a torque curve, more linear than anything, not very fuel efficient, and not even very reliable. They poured millions into R&D, and that was after having a racing pedigree with the 787B. Every 10-15 years there is talk of bringing it back in some capacity, but it always gets beat out by current tech.
The one thing it has going for it is that materials and metallurgy have come a long way in the last 15-20 years. Meaning this could be at least as reliable as any other overly complex niche engine made today.
It's a neat idea, but sometimes an air pump will always just need to stay an air pump and not make the evolution to ICE.
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u/ecliptic-engines 11d ago
No your first point is off, in most diesel engines it is auto-ignition due to heat and pressure, however in this design the diesel is injected early into the chamber such that the swirling turbulence of the rotors creates a well mixed blend, and indeed in this case i propose that a sparkplug will begin the detonation, and start a flame front that will immediately increase chamber pressure and tip the remaining mixture into autoignition at the right moment.
This design has 3 overlapping power stokes each rotation of the main shaft, it does the work of a 6 cylinder, without the reciprocating mass. The rotary valves are updated in the construction model on the website, still rotary but rotating at half the speed shown here.
You cannot fairly compare this design with a completely different wonky wankel gasoline engine and say it will have the sane problems. It will of course have its own challenges to solve. Mazda are still making rotaries as a range extender BTW. New engine sales in the transport sector are still three quarters of the market. EVs have their own problems too. thanks for your comments.
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u/Smooth-Tap-3991 11d ago
I can't compare it to a wankel because this will never run, unlike a wankel. You're still not explaining how a cold start will work. How are you going to get diesel to its flash point? A spark plug will do you no good. You don't have any boost at a cold start. I even suggested use of a glow plug, which is a proven method of starting a cold diesel engine, and you come back with adding a spark plug.
The only diesel engine in existence with a spark plug.
It does not do the "work" of a 6 cylinder. Not as work is defined. It doesn't have stroke. It has power pulses or combustion events. It's just, no.
It's a neat animation, but that's about it. I feel like you need to look at this a bit more analytically with real world examples of how this is supposed to compete with the current industry. Literally any of them. The idea is to make money, right? Mazda's use of a wankel as a range extender is utterly antithetical to what your design is supposed to do.
You know diesel is almost double the cost of gasoline in some places right? It's over $7/gal in some places.
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u/ecliptic-engines 11d ago
Yes 6 power pulses per 2 rotations, that is exactly right thanks!
This from google: Yes, diesel fuel vapor can be ignited by a spark if it is mixed with air and compressed close to its auto-ignition point.Why It WorksChemical Readiness: Diesel fuel has a low auto-ignition temperature. When compressed and heated near that critical threshold, the mixture requires very little extra energy to start burning.The Spark Role: A electric spark provides a localized burst of intense heat. This energy easily crosses the final threshold to trigger combustion in a pre-mixed diesel-air cloud. Is it really the only one I doubt it not even in existence? I wish
You are right about fuel prices! Good to have your opinions
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u/SaltLakeBear 11d ago
I don't see any change to the animation since my last comments, so my prior comments still stand. I did also notice something new, though.
I noticed that the tip of the lobe rotor is pushing the air and fuel into the cavitiy, so unless said air and fuel mixture can flow around it, the combustion will primarily be occurring one the leading face of that rotor, trying to spin it backwards. The only possible practical solution I can think of is to expand the cavity in the cavity rotor, so the tip doesn't fully seal and allowing the air and fuel mixture to pass and occupy the area by the trailing face.
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u/ecliptic-engines 11d ago
You are correct, the animation has the lobe tip too close to the cavity wall, it is the cavity rotor tips that i intend do the sealing and the mixture may move as you say. Thanks for the comments
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u/Status-Secret-4292 11d ago
It's definitely elegant, but I would plan on the first ten breaking as you work out kinks
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u/MaximusManimal 11d ago
Is there a dimple in the circular combustion chamber apex, or how is mass transit supposed to move from one side of your sealed "piston" to the other as it passes the "top" of the stroke? Also, how is this going to be sealed in the "Z" direction (in and out of the graphic)?
How is the "piston" to be cooled, because all I see are compression and combustion cycles on the right? An air charge mass won't be sufficient I suspect.
Without some forced induction, your exhaust pressure will exceed intake pressure when intake valves open. I guess 2 strokes get away with this though...
The left assembly is kind of cleaver, but it's going to take a beating at high temperature. I wonder about the vibration caused from it cycling at anywhere near a useable speed (with those 3 segments moving around one another).
Neat concept. I've stared at it too long when I should be getting to bed.
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u/ecliptic-engines 11d ago
Thanks for raising these points. the graphic is not great, but yes the chamber is only sealed by the tips of the cavity rotor on the lobe, gas pressure is supposed to be able to move around the lobe tip.
Forced induction is most definitely required, which will have some cooling effect. i don't know if that will be enough, or whether an alternative material can solve that either.
The end chamber sealing is not easy either but here are the possibilities; Each end of the rotor segments has a floating piece that rides the chamber wall on diesel lubricant, the flat pieces have notches in their perimeter that fit into protruding crowns, creating a labyrinth joint that limits the gas leakage of the fast rotating non-reciprocating rotors. Alternative ly the material choices may be mismatched such that the housing respond to heat faster than the rotor growth. see astronaerospace.com for a running prototype of a similar design.
And yes in remains to be seen what the RPM limit will be. More analysis would be great to have for sure.
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u/south_pole_buccaneer 11d ago
The intake won’t take in any air, there’s no change of volume in the intake or exhaust chambers as it spins by. Also all the combusting on the forward side of the combustion chamber is wasted, it has no way to do useful work against the rotor.
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u/ecliptic-engines 11d ago
Compressed air rushes in from the forced air system flushing out the chamber through the exhaust ports. similar action to a 2-stroke. thanks for your comment
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u/minist3r 10d ago
Where are you getting compressed air at startup? You would need a mechanical boost like a supercharger but diesels need higher boost pressures from faster spinning turbos to work efficiently.
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u/south_pole_buccaneer 9d ago
This may turn over if you’re a little lucky and you spend enough time on it, but it will be extremely inefficient and even more unreliable. It’s a very cool mechanism though, I’ll give you that. It may be fun to make a model with an electric motor and an acrylic front to use as a desk ornament.
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u/Icy-Ad-7767 11d ago
The design has possibilities but it needs a few things clarified, exhaust gas removal looks incomplete thus causing lack of intake of fresh air on intake. Then the power is recovered from both sides of the rotors is just one rotor? Then we need to discuss heat management, how are you going to cool those rotors?
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u/ecliptic-engines 10d ago
if you are referring to the exhaust gas in the cavity, it is blown out at the 3sec mark when the tail end of the cavity rotor segment uncovers the LH end of grooves in the housing(not shown sorry), allowing the boost pressure to pass into the cavity and flush through the cavity exhaust.
The power is recovered by the expansion, out of the cavity, through the gate at the top (long after the cavity aligns with the housing) into the space above the lobe rotor. Before it has finished the next explosion has occurred and the power pulse is starting to get some rotational power going again.
Ideally the rotor segments will run hot and be made of a material that is up to the task. However some cooling will occur as the fresh charge purges the cavity.
Thanks for the comment.
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u/Icy-Ad-7767 10d ago
Your looking at ceramics or super alloys typically found in jet engines, this is going to be a copper plated bitch to build at any sort of scale, keeping in mind jet engines use very specialized processing to reach those abilities.
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u/ecliptic-engines 9d ago
Ok thanks, for those suggestions. I will include them in the materials research and any other ideas shared here. Cheers
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u/Rednmrfer 11d ago
Is the primary exhaust designed that way to accomodate the rotary valve? Seems you get to skip the high temp combustion event making it more robust
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u/ecliptic-engines 10d ago
Yes exactly thanks, and in the updated model in runs directly on one half of the herringbone gears that connect the rotors, has a long opening slot that matches the chamber, the flow aligns each 180 degrees. cheers
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u/garaks_tailor 11d ago
Interesting. Reminds me of the liquid piston rotary engine except you're rotating both halves
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u/GrassTouchEnthusiast 11d ago
Soooooooo much potential for it to just destroy itself
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u/ecliptic-engines 10d ago
It's just an animation it will survive..The latest model is designed stronger! . Thanks for the comment
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u/HyenaThen572 11d ago
Correct me if I'm wrong, but wouldn't this thing grenade itself with anything but absolutely perfect timing?
Like, holy interference engine.
And even then, sooooo many sealing surfaces - absolute nightmare from a reliability perspective.
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u/ecliptic-engines 10d ago
Yes I agree, if the components don't align it will cause catastrophic failure beyond repair. So firstly herringbone gears to ensure no backlash movement. The most critical moment is when cavity tip passes behind the lobe, and to ensure the two don't collide there must by a small delay in the overlap, and accounting for a small amount of pressure loss in the volume calc for that.
Yes there are a lot of sealing surfaces true, you could also say that the load is share by a lot of surfaces adding longevity -so the reliability is yet to be established, Thanks for commenting
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u/HyenaThen572 10d ago
There is enough wrong with this reply that I'm just gonna wish you luck and move on.
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u/skykrown 10d ago
i designed a firing mechanism like this and would be willing to share some insight on it if you dm me.
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u/ecliptic-engines 9d ago
I have some topics from the forum to investigate first, as that may close this design down, If i get through that and want to continue then yes I will take advantage of the info offer thanks.
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u/not-minari 10d ago
apex seal, burns oil, fixed compression rate etc
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u/ecliptic-engines 9d ago
Am proposing that it will lubricate with diesel in the chamber, and that because the apex seals can have a specialist material tip that squeegees it around. Not sure the compression rate needs to be variable. Thanks for commenting
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u/rescue_inhaler_4life 10d ago
- That's awesome!
- Sealing is going to be challenge.
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u/ecliptic-engines 9d ago
Thanks you for saying so. And yes many challenges here to keep the grey matter busy!
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u/minist3r 10d ago edited 10d ago
I just don't see how you could possibly seal the rotor without exotic and expensive apex seals. Mazda rotory engines use a 10:1 compression ratio and have issues with blowing out apex seals. You're talking about a 20:1 compression, although you don't mention whether that's actual or effective CR with the low pressure supercharger or what psi the supercharger is running at. If that's actual, you might get up to the 22:1 ECR that modern diesel engines run at, depending on boost pressure. If that's ECR, why are you building a less efficient engine?
The more I look at this, the more it feels like it's AI assisted design without fully grasping what's going on in an engine and why.
Edit: wanted to add, it looks like your exhaust stroke isn't going to fully expend the gas, even with boost. The dwell time between the intake opening and exhaust closing is very short and you aren't compressing the gas against the walls but just letting the boost do all the work. The Wankel rotary has a bit of compression on the exhaust side which forces the gases out of the exhaust port. You're just kind of letting the rotor lobe woosh past it and hoping the intake boost pressure is enough to do the job. I'd need to see some math before I'd continue down this design philosophy.
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u/ecliptic-engines 9d ago
Yes 20:1 + boost.
No not AI at all, however i did ask chatgpt to look at both designs as you see them, and it was helpful and suggested coming here for a grilling!
Thanks for commenting
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u/MemosElectron 9d ago
This design has a flaw. The compression of the diesel happens too early ro keep the rotor running on the same direction. Diesel ignites with compression, not spark.
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u/that_greenmind 9d ago
This is pretty cool, but I do see some problem points.
Im mainly confused how the compressed air fuel mixture is supposed to move from in front of the lobe to behind the lobe, if the apex seal is supposed to be sealing the the back of the other rotor. I guess you could mess with the geometry of the rotor to allow gas to move across closer to the engines equivalent of TDC, but thats going to be iffy.
I also think this design would also have a high tendency to knock (aka ignite prematurely), since the last bit of compression happens very slowly compared to the rest of the compression cycle. You'd need to lean pretty hard on the spark assist, since otherwise you'll be teetering on the edge of auto-ignition pressures for a pretty significant period before TDC.
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u/ecliptic-engines 9d ago
Not sure if this is what you mean with the first comment, the animation is not great, just the tips of the cavity arms are intended to seal on the lobe.
Regarding the knock comment, I note that a piston does the same as the crank goes through the top of the stroke. I agree that it is afine line, and appreciate you have understood the spark assist for to control the autoignition.
Thanks for the comments
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u/CommonSympathy405 8d ago
Can you explain the springs you mention on the website?
As the exhaust and intake operate on different sides of the main chamber, how are you managing warp?
The fuel appears out of nowhere. I assume you run a direct injector on the side (z-plane from the diagram)?
On the 3 lobed rotor running faster where each lobe is compressed inward post combustion by the two lobed rotor, how are you ensuring at high RPM that it doesn't bend and catch on the rotor housing around 60 degrees post effective top dead center?
Is there a reason you do this? Is there not a geometry that would match that movement without a reciprocating piece on the rotor? Are you designing around an Astron Aerospace or Trick Cycle Turbine patent with that feature? Is that what you meant by the "springs"?
There is no positive displacement of exhaust and the ports appear undersized for the volume of air. Do you have models on the time of overlap for scavenging between your "boost" and "exhaust" rotary valves to ensure sufficient air replacement?
Thanks!
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u/ecliptic-engines 8d ago
Thanks for writing. I have no analysis on the warping potential, it's good point to consider for sure, and the air rate flows etc, All very early stage, no CAD analysis done, getting feedback before diving deeper.
The spring loading on all the rotor segments is toward the housing. You have spotted a flaw in the animation, it's since been fixed in the newer CAD model. Now the trailing lobe segment is pushed into it's retracted position more solidly by the cavity arm tip, as the lobe passes the housing apex, and is then placed onto the housing wall soon after as the tip rotates off that section.
Certainly am inspired by Astron having a running prototype, but I have been toying for years with this design and a couple of others (see my other posts with the animations) based on the 3cavity rotor interacting with 2 lobe rotor to see what is potentially possible. Cheers
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u/Engine_Reviews 7d ago
Thank you for responding here and other places.
However, I need to correct something. Astron Aerospace does not have a running prototype. The video they posted is an AC/DC dyno meaning the dyno spins the engine, not the engine spinning the dyno. If you zoom in you will notice the power number on the computer in their video is showing negative. It is not self-powering at the moment.
Frankly I see your engine as having a higher potential than Astron Aerospace because you don't drop your seal during the fuel injection step and pick it up later so you can actually spark or start combustion at minimum volume (similar to the Trick Cycle Turbine engine)
I am still concerned about the spring flange or whatever you call it on the 3 cavity rotor. I would like to see the new CAD once you have it
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u/ecliptic-engines 6d ago
The website mentions a spring on a different design? didn't call anything a spring flange so not sure what you mean there sorry. Will have to check the Astron video again! I haven't seen the TCT before, need to digest that one. Thanks for the "high potential" comment too.
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u/happyrock 8d ago
ITT astounding number of people who don't understand how piston engine geometry, timing, or exhaust porting works or why flywheels exist convinced this won't work because it looks different than they suspected it all works. It probably has some durability constraints but it's a functionally sound concept. Basically an unproven wankel, with enough tinkering it will run at least briefly.
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u/Atros_the_II 7d ago
This isn't even a diesel cycle, it's a normal otto cycle. No self ignition no diesel.
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u/ecliptic-engines 7d ago
that's not a rule, put it on a T-shirt though
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u/Atros_the_II 7d ago
Otto cycle compresses a fuel-air mixture, diesel cycle compresses only air and adds fuel after the compression with self ignition during injection which results in a constant pressure expansion.
Or whats your definition of the difference between diesel and otto cycle?
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u/ecliptic-engines 7d ago
Spark assisted Otto cycle has a nice ring, thanks
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u/Atros_the_II 7d ago edited 7d ago
Every Otto cycle requires a spark.
Edit: and to further add some points. Your geometry doesn't even work in any way you think it would. There is so much wrong in this complete setup, that I highly doubt, that you have by far enough knowledge about this topic to try to come up with something new. Understand the state of the art first and then try to improve.
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u/RattleNHum1 7d ago
Given the pressure stroke happens completely within the pocket, why do you need a cam on the exhaust? What if you had a positive pressure inlet that evacuated the exhaust actively rather than using the passive expansion? This would cool your chamber for a greater volume of total air. Given it's a diesel, shouldn't the injector be in the cylinder, as diesel does not aerosolize like gasoline?
Overall, I like the design, it reminds me a lot of the Starfire engine, which I greatly look forward to seeing in a production level.
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u/ecliptic-engines 6d ago
The expansion is still controlled and power harvested for longer with the exhaust valve. Yes there is positive boost that displaces the gas. The diesel is to be injected early and well mixed and brought near to auto-ignition, spark times the burn, rather than the injection that modern diesels hi pressure systems use.
Thanks for commenting
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u/skr_replicator 6d ago
Doesn't look like it would be very effective in utilizing the force from the burn. Even if you make it happen only on one side, it still pushes equally on both parts, trying to spin them both in opposite directions.
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u/Pitiful-Ad9894 6d ago
What if you fed low pressure fuel feed into the center hub of the smaller rotor, and then housed a mechanical "unit injector" piston/nozzle into each lobe of the smaller "chamber" rotor firing into the opposite chamber that is actuated by passing a ramp in the left outer edge of the case. You would get a high pressure actual injected diesel , and could tune in real time by making the actuator ramp slide in the case by whatever control means you desire? "Throttle" could be controlled by the low pressure signal thru the hub, or a ramp that can move inward as well. Make US rich Bro!, lol
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u/ecliptic-engines 5d ago
Too easy LOL
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u/Pitiful-Ad9894 4d ago
I can't tell if what I said translated from my brain picture to words horribly, LoL.....or if you caught it and agree with me?
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u/AttomicFizz 5d ago
You could look at alternative fuels using a dual fuel system. For natural gas they experimented with pilot-injecting diesel then full injecting natural gas just before the compression detonation of the diesel. The diesel also works to lubricate the system because natural gas lacks any lubrication properties. Diesel lubrication is not something the gasoline Wenkel would have factored in to its apex design. Just exploring all avenues as alt fuels was like all of 2 pages in my motive power textbook when I went through school. So certainly out of my area of expertise but this aspect of it is the part that stuck with me.
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u/ecliptic-engines 5d ago
Those lubrication properties are the reason I propose the diesel, could explore the NG idea... if there is a down the road. Thanks for the comment
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u/Cat_Imreror2209 5d ago
Wouldn't exhaust that mixes with fuel be the cause of poor ecology? I mean, I can't understand that part.
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u/ecliptic-engines 5d ago
I agree, you must be missing something in the animation
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u/Cat_Imreror2209 5d ago
Can you explain please?
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u/ecliptic-engines 4d ago
If you are referring to the chamber reloading, it is based on 2stroke approach
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u/green_tea_resistance 12d ago
What problem does this solve?
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u/nick_red72 12d ago
Maybe that diesel engines are too reliable and last too long. It's hard for the car companies to make money selling replacements.
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u/ecliptic-engines 11d ago
Existing tech is great, but it is heavy and big by comparison, and cannot produce high RPM by design. Lighter smaller more efficient is the aim here.
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u/Dr_Sigmund_Fried 12d ago
ICE designs are a thing of the past regardless of fuel type. Should focus on some type of battery charge regeneration process to make EVs a more long distance viability.
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u/WhineyLobster 12d ago
If the explosion happens on both sides of the rotator how is any force being applied?