In this video we analyze the engine invented by Gerhard Smith. Did you know this 5-stroke mechanism? #repairman22 #power #5stroke #horsepower #speed #turbo #engine #3danimation #3d #gtr #golf #stroke #4stroke #2stroke
An additional process (the second expansion) doesn't make this engine a 5-stroke. The intake and exhaust are overlapping, so whole cycle still completed in just 4 strokes.
imo if its not 4 stroke then its 6 stroke at best usual 4 stroke into expansion and afterwards exhaust, the optional water injection is part of the expansion stroke.
There are two cylinders. Thus, there are 4 strokes + 2 strokes = 6 strokes, but two overlap, giving 5 stokes. The process takes 5 strokes: Intake, Compression, Power, Transfer&Power, Exhaust. "Strokes" relate to processes. This gets more complex and debatable when two different RPMs are used, such as in the engine I'm developing. The induction pistons runs at 1/2 speed, so the engine has eight strokes: Intake, Intake, Compression, Compression&Transfer, Compression, Power, Transfer&Power, and Exhaust.
no this is not a5 stroke motor, and you can get a 4 stroke single cylinder engine, i would believe you that this a 5 stroke engine but we would both be wrong@@RichardLewisCaldwell
A compound engine using the same double expansion design (three cylinder with the centre being used for additional expansion) was built by the German Deutz company in 1879. A five cylinders compound engine was built by the Frenchman Forest-Gallice who patented in 1890. Rudolph Diesel, father of rolling coal patented his three cylinder double expansion engine in 1897. Edward Bales of Illinois patented his three cylinder compound engine in 1897 The three cylinder Crossley-Atkinson (of Atkinson cycle fame) compound engine was patented in 1903. These designs all suffered the same problem as the one in this video is likely to suffer; the loss of heat from the gases being passed from the high to low pressure cylinder coupled with the additional friction of the additional cylinder negated the efficiency benefits. Gerhard Smith was very late to the game.
And all of those ideas came from the steam engines of the time. With a small piston for HP steam and a larger one for low pressure steam. Even steam turbines work on this same principle, but with less mechanical parts.
There we go, i was wondering why this wasn't thought of before, as it's effectively just an in-block turbocharger in piston form, connected directly to the crankshaft. Makes sense this idea is about as old as the concept of super/turbochargers. It's just more power instead of more air, after all.
@@agt155 So to make the usual Atkinson cycle engine you have to add a generator/motor, 1/2 a ton of battery and a load of control electronics, that all add expense along with the weight. Because the valve controlled FIAT system can instantly go from Atkinson cycle to Otto cycle, it can provide both high and low power efficiently, without having to add a motor and battery for low power.
You’re right. It is “silly”. But buying rather precise parts is easier than designing and milling custom parts. The same reason the four-banger was altered to be a two-banger with a klugey re-expansion ‘cylinder(s)’.
I just came from the wiki. I want to quote the cycles here, and offer a criticism: 1, induction 2, compression 3, power 4, exhaust expansion 5, final exhaust Thats fine, if all the cylinders moved in parallel. When the final exhaust is the expansion cylinder going upward, that would imply that the power cylinders are going downward at the same time. So cycles 1 and 5 are effectively the exact same cycle. Its still a 4 cycle engine, with an expansion cylinder. Not a 5 cycle.
This is essentially an atkinson/miller cycle engine with two pistons, but with the vibrational balance of a four piston engine. The "extra moving parts" problem can be fixed by simply increasing the lobes on the camshaft, an extra camshaft and gear/chain mechanisms are not needed. The current miller cycle engines are limited by the stroke of their pistons; to make the expansion stroke double the length of the compression stroke, you can only use half the stroke for intake, limiting your power greatly. This engine solves that problem in a very intelligent way. I would have loved to see further development for this, I think there's incredible potential for high performance and high efficiency engines here. With enough funding it could start a sports car Renaissance.
I'm not convinced this actually solves the limitations of the Miller cycle. You're going from 4 partially filled cylinders of air to 2 full cylinders of air, which isn't really allowing you to get more air when you're still moving 4 cylinders of mass around. Also, instead of over expanding within the first cylinder, you're wasting some energy going through the transfer pipe.
@@Appletank8 you are correct, however the video claims 130 horsepower out of 0.7 liters of displacement. In theory, you can use a pseudo v8 configuration with larger cylinders for some crazy power with the fuel consumption of an economy car
@@ulasgursoy2838 Is it really 0.7 L of displacement though? It's still carrying around 4 pistons of weight and friction, and it's practically unusable at low RPM. It wouldn't be that far off from a 1.4L engine expelling half of its intake. A similar engine is the 1.5L M15A-FKS, which gets 123 HP at 40% efficiency, and is usable across all regular RPMs. I'm not seeing that much advantages in this 5-stroke engine here, unless they have an efficiency chart that points out its efficiency range.
Yeah I'm thinking if it "only improves efficiency under high load," then like... just make a high-revving lightweight version for sports cars, where its drivers will be happy to rev it to the moon and get decent fuel economy doing so. Economy sports cars would be fun.
Like others said, it's basically a double expansion engine. It was sometimes utilized in steam engines, but mostly not: if you pull back the johnson bar, this allows steam to work by expanding inside the cylinder instead of just pushing the piston with its pressure, and so by the time the steam is exhausted there's simply no pressure left to drive another cycle of expansion. In other words, double expansion only allows for more efficiency at maximum power setting, and doesn't do anything otherwise. That's fine on a power plant or a sea-faring vessel, but in motor vehicle applications you don't usually even use the maximum power setting, and the added complexity and weight isn't worth the benefit of slightly reduced fuel consumption when you're pushing full throttle. Which is why this extremely old technology which is also a no-brainer to add to a piston-based engine haven't found its way into production cars and trucks. In ICEs specifically there's an additional array of problems such as carbon buildup which can't be self-purged from a cylinder that never burns fuel.
Well thought out, I hadn't considered the carbon in the expansion cylinder, it would be like a gdi engine's valves not having the fuel flowing across them to clean them.
Good point. Fortunately, using a piston-topper to segregate the hot gasses from the piston allows surfaces to run above the temperature where carbon buildup occurs. “Engineering Explained “ has a good video. Search “Italian tuneup”.
I would be interested to see how this compares to a turbo 4 stroke. With the added points of failure and rebuilding of a crankshaft, it seems like a tall order when compared to current forced induction methods. The concept is interesting, regardless, and the video well put together.
Very clever, it's easentially it seems to me the same concept as the power recovery turbines on the wright turbo-compound radial engines, where the exhaust spun a turbine that turned a shaft and put that power directly back into the crank...
We don't make these because the exhaust strokes themselves (the upward motion of the 4th cycle) of the smaller cylinders are what drive the 3rd piston, not just expansion alone.. you'd need a LOT of wasted expansion from the smaller two to get any meaningful power out of the 5th stroke.. if you're wasting enough expansion on your power strokes to drive a whole separate 3rd piston as a 5th stroke without any frictional and inertial losses, I still don't see any advantage other than packaging. It's kind of a silly proposition. This is basically a turbocharger turned inside out. And you're far better off with that turbo, which is essentially doing exactly the same thing but in a much more effective manner; Harvesting the wasted heat energy from exhaust gasses.. Without the extra friction and inertia loading of an internal 3rd-piston 5th stroke
Yeah, but a turbo doesn't drive the crankshaft, it just decreases the energy from the compression stroke necessary to compress the mixture to the desired compression ratio. So i don't think this engine on its own is less efficient than a conventionnal downsized turbo 4-stroke, but if you add the fact that an additionnal turbo on the 5-stroke takes further advantage of the residual pressure in the exhaust gas, you could potentialy have more efficiency. And the final advantage is the water injection : turbo and/or 3rd piston are not very good at recycling heat (as they both use exhaust pressure), whereas water injection is, making the engine even more efficient. Of course, as water injection cools the cylinder, it decreases the pressure of the exhaust gases in the 3rd piston and the turbo (thus loosing a part of their benefits), but there could still be a net efficiency gain, especially if you use highly heat conductive materials to drive the heat from the power cylinders to the 3rd, in order to recycle it more. Other ways to achieve this could be to make traditionnal turbo 4 stroke engines, but with the 2 center pistons dedicated to collect the heat from the two others (they would only be injected with air/water mix), which would then allow the motor to use the two steam pistons as coolant, instead of a pump driven radiator, and allow the water to be condensed and recycled as their exhaust would be only steam and air.
The animation is off, the exhaust valves of the middle cylinder should open every time the middle cylinder rises, they now only do so every second time the middle cylinder rises. The voice over says the middle cam rotates twice as fast as the normal cams, but the animation shows it rotating at the same speed.
Thanks for that bit at the end about compounding a standard 4 cyl engine. I had thought about doing just that but was unsure if it would be worth while. This just saved me a bunch of time.
First thing I thought when I saw the diagram was a steam triple expansion engine, which is suppose this is a variance of...Speaking of which, couldn't said steam on the water injection be recycled, again such as the old ship engines did?
I'd love to see an exhaust turbine similar to the posche 919 added. The 5 stroke engine design has fascinated me for years and i believe it has a future as an efficient generator design
You could probably get away with heating the intake with the exhaust since you have the extra expansion. The problem with doing this on regular engines is it effectively increases the compression ratio by increasing the temperature of the air without increasing the expansion ratio. So more work is done to compress the air without actually getting that work back through expansion. This has shown to increase the efficiency of turbine engines.
I believe heating the intake would decrease the air density leading to less power and the warmer F/A mixture will more easily pre-detonate leading to lesser compression and retarded spark timing to compensate
3:21 a similar system was in the F-80 Shooting Star where water was injected into the exhaust of the jet where the water turned into steam providing additional thrust
its so similar to a steam engine, a double expansion or triple expansion, where a small piston initially has the high pressure, then a second piston (much larger ) has the exhaust of the first cylinder, which would otherwise be wasted
The exhaust gases need to still have enough energy to keep the after treatment hot. Otherwise it can never pass the current EU6 and defiantly not EU7 requirement. There legislations are actually extremely hard to meet even with a regular 4-stroke engine!
Turbo relies on also putting more fuel in the combustion chamber to accommodate for the increased air density (more power => more fuel consumption). Like the turbo, the center piston uses exhaust gas and pressure difference to operate. However, this engine doesn’t need extra fuel to further assist the turning of the crankshaft (more power => same fuel consumption => more efficient)
What it's actually similar to are Miller Cycle engines. They expel a portion of the intake in order to have a longer power stroke. This ""5-stroke"" has half the intake for the same "expansion" ratio, or 0.7L of compression, 1.4L of expansion.
Yes a turbo makes use of the waste exhaust pressure but does so in a way to increase air density and thus more fuel and power, but not efficiency. This design increases the efficiency (and to a smaller extent) and power of an engine without using more fuel
@murraymadness4674 True, but the smaller engine will still typically use the same amount of fuel as a larger engine when producing the same hp, they are still burning the same amount of air and fuel the smaller boosted engine is just cramming it all into a smaller space. Thats assuming they are running at full power however, realistically the smaller boosted engine will spend most of its time off boost and thus will be using less fuel than a larger NA engine
To further enhance efficiency, a catalytic converter can be added to the manifold that feeds the central cylinder. That would add heat to the flow into tue center cylinder and enhance the water injection as well.
Could be tricky to actually pull off with the limited space available over the short transfer port lengths but it makes thermal sense to me. It seems to me that the shorter the transfer track the better. EDIT: Given that the engine is already has a restricted effective RPM range I suspect that there would be an ideal transfer port length that would be able to take advantage of harmonic gas wave effects like a tuned length extractor exhaust system. That may even enable room and gas dwell time sufficient for your catalytic converter idea. The narrow usable RPM range would be likely to become even skinnier though.
@@ddjohnson9717 the chemical reaction that is catalyzed is exothermic. Cats introduce a flow restriction though, thats where they sap performance especially because the extra heat produced is normally always completely wasted. In this twin expansion design though, that energy goes to enhancing efficiency Edit: some people prefer dogs anyway.
@@lordchickenhawk the port should be built into the head, I'd think. The catalyzer needs to be an insert that fits in place. If you are converting a 4 banger then maybe simplicity is a better option.
@@lcambilargiu Yeah, I think so too... like I said, space would be the tricky bit, either way. And the flow restriction you mentioned to ddjohnson would present further difficulties. I like your idea but I think it would be very difficult to it pull off in actual practical application.
They make it sound this this is a new design or development, I remember researching about this when I was a kid about 15 years ago. Still a neat design, has definite potential for stationary engines and generators
What an excellent explanation! Showing all the different models of this idea felt like an adventure! I love the simple conclusions at the end. The friction and complexity remind me of the opposite type of engine used the Sachsenring Trabant 601. Boy I want to see that animated so bad.
Hi! Some years ago I made water injection system on my VW Golf Mk2. No fuel economy. For right operation this setup needs control temperature of the engine before we can inject water, because if engine temperature is low, we get situation of no combustion/ motor stops. In F1 engines in old days they use water injection only in extreme temperature/ pressure/ knock prevention situations. This thing works only as engine horsepower booster when engine is hot. Be happy! :)
@@jiroyamamoto2878 Yes. For me - in my setup - it works very fine in very hot summer time when asphalt reach extreme temperatures. Lean mixture and cold water mist temperature makes it ideal conditions for clean/ humid/ powerful combustion - engine inside and manifolds was clean always and it gives very quiet engine work. If there is Arduino between all that parts and if it is controlled everything - it will work fine - beautifully! My system was not so advanced and it blows up in one day :)!
Toyota hybrids operate on the Miller-Atkinson cycle; they just close the intake valves later to make the expansion longer than the compression with good efficiency at low speeds. No need for an extra cylinder :)
These would make for great small generator engines, especially stationary ones. Even better on small long range ships since they already would need a water purification system. If you remove the water injection, they make for great airplane engines. If used on cars, they could be used as gas over electric hybrid vehicles similar to the Audi Dakar racecar. As other commenters pointed out, the catalytic system would have to be built into the block as the exting low temperature water-contaminated exhaust would not be compatible with traditional systems. Another idea would be to us the waste pressure and heat to drive a separate turbine as a multi-cycle engine. Again, this would likely only be most efficient at specific engine speeds and would increase in efficiency with scale. A good in between would be to use a turbo as in a car engine, it's very nearly the same concept, yet less complex and more flexible.
I remember seeing this very setup in an old Engine Design book from the early 1920s. Same process but it used a standard cam in the block and pushrods driving the overhead valves. I believe the Engine was from about 1915...
It's because you don't just need regular water but distilled water, as using regular water with lots of impurities in it will ruin the cylinder real quick as mineral deposits starts building up on the cylinder walls.
I think the Argentinian pendulum engine is the best non mass produced engine variant. Oil isn’t required because there is no friction and 100% goes to turning the crankshaft instead of rubbing the cylinder wall
Also, the expansion piston could be coated to retain heat. Something you don't want with a normal shiny aluminum piston. As that leads to pre-ignition under normal conditions. But the expansion piston, if it retains heat, would be more efficient at converting the water to steam instantly.
Better to run the second expansion cylinder on something like 1-way valves like reed valves. Also, to combat the loss of efficiency at low load and the lower pressure/energy causing turbo lag, make the second expansion cylinder the same size as the normal cylinders instead of 2x the size. Also make the whole engine in general "under square" for thermal efficiency. Also, for better frictional efficiency, you could make the whole thing a Taurozzi Pendulum engine.
Making the second expansion cylinder the same size as the primary cylinders defeats the point. The reason it's larger is because it requires less mechanical force to push a smaller chamber's volume into a larger one. if they were the same size, the force pushing back on the primary cylinder would completely negate any force imparted on the secondary cylinder, and you would run at less efficiency than if you didn't have the secondary cylinder at all because it would just be dead weight.
The biggest issue I see with this engine is that the central LP cylinder gases it’s cam timing locked to the HP cylinders. This prevents it from having variable expansion ratios, giving the engine only a small band of high power and high efficiency.
One downside I see is a problem my 3-cylinder Geo Metro had. It would burn out the center intake valve because the exhaust gas was too hot. Hopefully this engine has better steel alloy to avoid that issue.
I had a similar idea - but I was thinking oof using a standard 4 cylinder engine custom cams and modified intake/exhaust manifolds. Basically this thing is like the gas version of a 2 stage compound steam engine.
Get rid of the valves on the central piston & just have exhaust ports at the bottom of the cylinder like in the 2-stroke diesel, use a V3 design for more direct flow & shorten the exhaust travel into the cylinder & don't upsize the exhaust cylinder.
The double speed cam in the animation is turning same as right hand intake cam, so once left hand cyl exhaust sroke fills centre bore it has nowhere to go but to get compressed again
If you put catalytic converters between the cylinders, such that the exhaust from the HP cylinder goes thru the CC before entering the LP cylinder, that might improve both efficiency and emissions. My 2c.
It seems to me that this cycle could also be used in combination with your previously described Mazda 2-stroke engine. In other words a two piston engine design, with the small cylinder operating according to the Mazda 2-stroke cycle, exhausts into the large cylinder using water injection as described in this video. Would that make it a 3-stroke engine? ;-)
I attempted to patent exactly this, some 15 years ago (totally oblivious that it was aready in development stage, under the title "double expansion / internal combustion engine". I hade the same layout, two smaller pistons either side of a much larger piston. Kinda freaky, but just convergent evolution i guess.
Good Day : At time about 3:23 "Water Injection" what an excellent idea . To get that clean de-mineralized water , all you would need is a "Water Maker" . These are small and compact and can also be seen in regular use on board Navy ships .
In my opinion you can get the same effect with the Miller or Atkinson cycles. The advantages of these cycles is that you keep the number of moving parts. Using these cycles it is also possible to vary the compression to expansion stroke ratio. So you can operate the engine in the Otto cycle limit for best power and in the Atkinson or Miller cycle for best efficiency. In general, all these engines are much to complex for unexpensive manufacturing.
It seems like you could achieve a similar thing using a regular Atkinson engine with just the exhaust portion of the turbo connected to a generator like on a formula one engine. You also don't really need the turbo to compress incoming air, so a regular high-compression NA with an exhaust turbine would be more efficient.
Agreed, but only if you have somewhere to use that power in the drivetrain. This engine converts exhaust pressure directly into mechanical energy at the crankshaft. The turbo-style generator would first convert mechanical energy (moving gas particles) into electricity, then somewhere down the line convert back to mechanical energy through an electric motor. The added two steps converting energy may end up being less efficient, but who knows 🍻
@@oscarschott8905 You're right, but most engines already have an alternator which could be upgraded (like some modern engines - see the Jeep Wrangler 4xe and Alfa Tonale hybrids) to a 3-phase motor generator. That also means you can remove the starter motor from the engine because the 3-phase belt-driven motor can start the engine. These motors can be upwards of 90% efficient, and I believe turbines can be similarly efficient to pistons as well while taking up a lot less space.
@@oscarschott8905 but this engine is only suitable for electric generation anyway. The additional benefit of a separate turbine generator is that you can put it after the catalytic converter to scavenge some additional heat, introduced by the reaction.
As you mentioned that 5 stroke benefits only higher engine loads, forget cars and motorcycles and add marine and aircraft engines to generators and range extenders. The need for those continuously high load engines are million units a year. This innovation really has markets.
Lol, no, there isn't a third cam for the center exhaust, there's just an extra exhaust lobe on that cylinder's section, so it opens each time the piston rises.
This engine is very interesting. It shows that there is more researches on the piston engine. Why isn't there more researches on the turbine engine for vehicles?
Such products say more about the tenacity of the inventor than about the effectiveness of the invention. And in the end it is proved: in general more disadvantages, and the advantage only in special conditions.
Build up on intake cams / ports to middle pistons will be an issue...and if stroke is variable (nissan VC technology)... the low load issue could be solved...
As a further simplification, why not just put two sets of lobes on the center piston's cam shafts so you can drive them from the same shaft without gearing them up?
Well if you add a small electric engine to handle the low rev states of the car (like the ones found in hybrids such as e.g the Suzuki swift hybrid) I think you can negate the negatives and take advantage of the positives of this engine type
I had the same idea, but any increase in the volume of the transfer tube decreases efficiency: At the point when the transfer tube opens, you have the high pressure cylinder fully expanded plus the volume of the transfer tube (plus zero from the low pressure cylinder because it is at top dead center). When the transfer is finished, the exhaust gases are contained in the full volume of the low pressure cylinder plus the volume of the transfer tube. Assuming that the swept volume of the low pressure cylinder is twice the volume of the high pressure cylinder (which you probably don't want to stray too far from because of the weight balance of the pistons); If the transfer tube has the same volume as the small cylinder, then that results in a 2:3 expansion; if the transfer tube has the size of the large cylinder, then you only get a 3:4 expansion. Ideally the transfer tube would have no volume, which gives you the full expansion ratio of 1:2.
I am glad to be the first comment writer. I opine that proposed engine needs further funding and research to weed out the problems and refine it. Funding often differentiates failed engines from successful ones.
Another big drawback is lower power density from mass and packaging perspectives. You still have that big engine, but with the displacement of a 2 cylinder.
That is just a great idea; also, an engine like that almost needs no exhaust muffler, at least way less expensive; it WAS always very sad to me, to see engines exhaust with a BANG,(remove the exhaust manifold, and you'll see...)meaning that A LOT of energy was wasted; For racing, the center Piston can be used as a "Turbocharger", a Blower.
So it uses the pressure of exhaust to turn the crankshaft. So a turbocharger, but instead of that rotational energy going into bringing in more intake pressure, it goes straight into the crankshaft. So really, an inverse supercharger, instead if using crankshaft energy to bring in more fresh air, it uses exhaust to give more crankshaft rotation.