5-Stroke Engine - Operating Principle

5-stroke engine, the alternative to the 4-stroke engine.

[jackychan]

Very good idea to lengthen the expansion ratio to retrieve maximum fuel combustion energy on the low pressure piston. In the Steam Era, triple expansion marine steam engine seems having the same principal to extract maximum steam engine, keeping the final exhaust pressure near zero or even vacuum when before passing to condenser, great work, hoping would be success on coming time.

[ManWithBeard]

Expanding the hot air to a larger volume than was ingested during the inlet stroke is always good for efficiency. It's harnessing the energy still present in the exhaust gases which otherwise would just get vented out the exhaust valve, chuffed out, blown off, wasted as heat and noise. Like turbocompounding, or some Atkinson or Miller cycle engines, this has the potential to perform better than a standard Otto engine. Good job.

[jbindics]

This is an amazing concept. What is difficult to understand, why did it take 100+ years to come up with this idea 😊

[Slouchification]

This is a great idea! Not only do you get to use fuel to a much greater efficiency by burning it twice, but you also recoup energy from pumping the exhaust out.

[maddhatter]

when i was 16 i had a concept i drew of a 5 stroke. the first 4 were conventional but added steam (water injection) in the final cycle. i have seen 1 video of a guy that tried it with limited success

[Lcsk]

Make the middle piston rotate 180º, this way both volumes of the expansion cycle are added. Say that cilynder 1 and 2 has 1units and 3 (middle) has 3units, the way it is vol 1 is sibtracted from vol 3, 3-1=2, cil1 is contracting and cil 3 is expanding. The way im suggesting at the power stroke both cilinders (1 an 3) are expanding, 3+1=4, a 100% increase of volume expansion. the drawback is more reciprocating mass wich can be countered by a balancing mecanism.

[rdGenGuy]

SO all it does is use the exhaust from another cylinder to push the middle piston down.

[rebelusa]

Why we dont see 5 stroke engine on the road.

[SCmaro]

Reminds me of how the old piston steam engines operated. I wonder if it would be more efficient still to direct the exhaust into a turbine that can somehow either directly contribute power to the wheels or store it electrically like a hybrid for later use in addition to or rather than dumping it into an additional piston.

[BaileyEvans]

interesting, it's like the old multi stage steam boat engines, but they have up to like 4 different sized cylinders.

[danielthompson]

Would it be possible to ignite both power cylinders at once? Seems like it would be a better design since you'd have higher volume of gas and more efficient power stroke in the center

[dallatorretdu]

I think that it will work, it's the same principle of double/triple expansion steam engines but I don't know how IllmorUK can have a 140hp/liter engine if one cylinder (the biggest) is not working as powerful as a classic one!

[MaxLeeMe]

This is a great idea!
But if we're simply utilizing expanding exhaust gasses, then its easier to simply turbocharge the motor and tune the engine economically.  Rather than add another (almost 2 cycle) piston into the engine

[isaaclowe]

the problem I see is the exhaust piston is going to fouled up becouse there is no fuel being introduced to keep it clean, also catalytic converters have to have a specific heat fuel and air to work properly, but I'd like to see if they find a way to solve these problems

[tiberiupetrescu]

Could there be a diesel alternative and if so would the emissions be lower than a 4-stroke diesel?

[OVshyguy]

shouldn't the extra expansion cylinder be smaller? that way the expanding gasses push the piston down.

[wernerschulte]

Gebaut wurde sowas schon von einem englischen Motorenentwickler (fa. Hart?), hat auch bei bestimmten Betriebsbedingungen einen achtbaren Wirkungsgrad. Aaaaber, die Restenergie des Abgases ist bei den üblichen Motoren nicht mehr so groß, dass der Ausnutzung einen größeren mechanischen Aufwand rechtfertigt. Im Auslegungspunkt bläst wird das Abgas beim Öffnen des Auslassventile überkritisch abgeblasen, währen der Restdruck im Zylinder noch Arbeit verrichtet bis möglichst zum unteren Totpunkt. Diese Drosselverluste durch das Abblasen werden auch durch Turbolader nicht eliminiert. Beim Fünftakter kann man mit dem Überströmdruck spielen und ihn so hoch setzen, dass das Abgas unterkritisch strömt und weniger Verluste entstehen. Allerdings muß der mittlere Expansionskolben das weitgehend entspannte Abgas auch wieder ausschieben - was Energie kostet. Er braucht also ein sehr großes Auslaßventil, was mit den beiden Einlaßventilen des rechten und des linken Zylinders nichts in Konflikt kommen darf. Es wird schnell deutlich, dass das Konzept nicht für hohe Drehzahlen geeignet ist.

Besonders dumm wird die Geschichte, wenn im Teillast gefahren wird. Dann ist der Abgasdruck vor Ausströmen aus dem Verbrennungszylinder so niedrig, dass das größere Volumen des Expansionszylinders nicht mehr gefüllt werden kann. Dann "saugt" dieser Zylinder seinen Vorarbeiter leer und verbraucht Energie, die er beim Ausschieben nicht mehr wieder bekommt.

[bowpilot]

Basically the same principle as a compound steam engine .. the centre piston has a larger bore to take advantage of the lower exhaust pressure from adjacent cylinders .?

[TheEsseboy]

nope, they expand in the extra cylinder, reduces the exhaust tempreture and gaining power, up to 186HP/Liter and you`re turbo will live longer due to lower tempretures!

[brettknoss]

What if instead you had 4 cylenders of equal size, and camless valves so it can opperate as a four or five stroke?