Opposed-Piston Engine (3D-Printed)

compressed air engines i've made a few of them recently all single cylinder and all with one piston per cylinder the way these engines produce power is pretty simple high pressure air is released into the cylinder and as it expands it forces a piston down the cylinder which is attached to a crankshaft which converts the linear motion to rotational motion the cylinder head means the air can only expand in one direction which in the case of these engines is exactly what you want but what if i removed the head of the engine so we now have an open cylinder well then you can put a piston in the other end of the cylinder so now you have two pistons in the cylinder so what we have here is the beginnings of an opposed piston engine so that's what i've built a 3d printed opposed piston engine but before taking a look at my engine and how i overcame the various problems throughout this project i think some background is needed [Music] the opposed piston engine is not a new idea in fact the first design dates all the way back to the late 19th century and was developed in hampstead a british gas engineer by the name of james atkinson invented the first opposed piston engine and he called it the atkinson differential engine the engine used a slightly modified version of the otto cycle humbly named the atkinson cycle because why wouldn't you name it after yourself in the end the engine was a commercial failure largely because the atkinson cycle sacrifices power output for increased fuel efficiency which 19th century industrialists weren't too bothered about [Applause] fast forward in 20 years a car powered by a 15 litre opposed piston engine became the first car to exceed 100 miles an hour averaging a speed of one hundred and three and a half miles an hour over a one kilometer distance the fact they measured the speed in imperial units and the distance in metric units pains me some of the most noteworthy opposed piston engines were a series of engines known as junkers jumos these engines were developed by another extremely humble man by the name of professor hugo junckers the most well known of these engines was the gmo 205 which was a six cylinder 12 piston 690 horsepower diesel engine and over 900 of these were produced and were used in airplanes on both sides of world war ii as well as their use in aircraft opposed piston engines were also used in submarines russian tanks [Music] trains and even trucks however in the 1970s the us enacted the clean air act and this effectively stunted the development of opposed piston engines for road use for the next few decades because these engines couldn't meet the mission standards that is until 2004 when james lenke and john walton founded aktie's power the company's goal was to develop a two-stroke opposed piston engine that can meet modern emission standards akiti's power has claimed that in comparison to a conventional engine their opposed piston engine is 30 more efficient than a diesel engine and 50 percent more efficient than a gasoline engine this also comes with lower co2 emissions and lower knox emissions so it seems like a win-win so let's have a look at how this engine actually works the engine has two crankshafts with each crankshaft attached to three pistons as you would expect from an opposed piston engine the pistons move towards and away from each other in a synchronized manner these two crankshafts are geared together to drive a single output shaft that will be used in this case to power a car or truck unlike conventional engines there are no valves for the inlet or exhaust gases instead open ports are used to allow fresh air in and exhaust gases out looking inside the engine a bit further we can see that when the pistons are at bottom dead center the airports at the top and bottom of the cylinder are exposed fresh air is pulled in through the bottom port as exhaust gases are forced out of the top port the pistons then move towards each other meeting at top dead center where diesel is injected and combustion occurs forcing the pistons back out and exposing the airports once more restarting the cycle as this is a two-stroke engine there is a power stroke every time the pistons meet at top dead center this design is what i'm going to base my engine design on but as mine is running on compressed a there's obviously going to be a few differences in an ideal world the designing of this engine would be a lovely linear process we live in the real world and in reality it's a nightmarish mess of iteration after iteration until i finally get to the first design because more often than not parts break or they don't fit either because of tolerances or because i'm an idiot and i can't 3d model so to try and keep things simple for now i'm just going to go for a single cylinder so that i only need one air inlet and one valve system so here's the basic idea of my first opposed piston engine pneumatic fitting is attached to the rear of the engine and the air supply is connected to this the air supply to the engine will be controlled by a single slide valve in order to try and minimize the amount of a that leaks to the slide valve i'm going to put graphite rods in the valve assembly the fit between the rods and the slide valves should be sufficient as to prevent significant leakage i am also hoping that as graphite is used as a lubricant as well as steel in the engine it will also lube the slide valve reducing the resistance the slide valve will be opened by a cam which is attached to one of the crankshafts and is then returned to its initial position by a tension spring when the slide valve is opened the high pressure a will be charged into the cylinder the high pressure a expands in a cylinder and forces the two pistons away from each other in opposite directions as i alluded to previously there are two crankshafts one for each piston the crankshafts are then geared together to drive a singular output shaft which can be used to power something i printed off a lot of parts tested this i mean a lot oh i made a few design changes along the way such as printing the crank con rod and gear assembly as one piece this meant i didn't have to try and align the gears with the crank which was proven difficult i also 3d printed my own bearings so that i could use a bigger output shaft to prevent it from snapping i could have bought new variants but i'm cheap all the parts are printed now all that's left to do is assemble it and see if it works [Music] so this is going to be the first test of the engine and honest thoughts i don't think it's going to work on to just above 10 psi open the air valve well that was dreadful okay 20 psi this time three weeks of designing and printing and it doesn't work and at the moment as far as i can tell it's because of this specifically the slide valve the graphite rods which i hope would seal the valve don't so basically the air is just leaking out all around these gaps in the valve so i've got one idea with how i can fix the ceiling issue on the slide valve and if that doesn't work then i'm so i slightly alter the valve design so i sealed it with o-rings on both sides and it still doesn't work [Music] so as well as leaking out the sides it also leaks out of the main port when the valve is closed so yeah it's absolutely so now i think my only option is to redesign the entire engine around the new valve design i've been working on this for about three weeks already and all i've done is rule out the slide valve so i've wasted three weeks of my limited time on this [Music] so here we are again two weeks later with a complete redesign of the engine so i've got rid of the slide valve and replaced it with a valve design similar to what i've used on my previous engine it's basically just a ball bearing that sits in an o-ring the valve is opened by a push rod and then closes itself once the pushrod drops the timing of the opening and closing of the valve is controlled by a cam attached to the output shaft of the engine i made a few other changes too which i hope will improve the engine such as decreasing the complexity of the crank and decreasing the amount of friction in the engine each crank now only has one bearing compared to the previous engine which had two per crank i have used an extra bearing on the output shaft to ensure that it remains as straight as possible but even so i've still decreased the amount of bearings in the engine from five to four and i actually bought some bearings so that i'm not using a crappy 3d printed one i think that's enough talking i've been waiting two weeks to give this engine a test so let's do it [Applause] [Music] let's give it a go please work come on please work please work so it worked once kind of but then i couldn't get it to start again so because the engine's leaking i've attached this valve so i can close off the air supply to the engine while i'm pumping it up i had a feeling the flywheel was too small so i printed a bigger one but this didn't seem to help so then i thought maybe the force exerted on the ball valve by the air pressure is greater than the force generated by the engine this would mean that after i've spun it once the engine doesn't generate enough power to open the valve by itself so i decreased the valve size from seven millimeters to six millimeters to see if this would help so i don't know why it doesn't work i actually think i'm gonna have to cut my losses with this engine i can't figure out why it doesn't work [Music] but just before putting the model to rest i decided to check the fusion 360 model one more time and i noticed in the model the composition was in the wrong place with the valve being opened just as the airports are exposed so the model was showing me that the air inlet valve opening and the exhaust ports being exposed were at exactly the same time so this would mean that any air charged to the cylinder was not forcing the pistons back and was just going straight to exhaust but surely i wasn't stupid enough to replicate this mistake on the actual engine what are you an idiot sandwich so i readjusted the cam position so that it would open just off the top dead center i then reassembled the engine for one last test [Music] yes it it works it finally worked [Music] great success so now i know it finally works i'm going to finish the assembly by adding an acrylic sheet to the back with some exhaust ports and then i can do some testing [Music] with the acrylic sheet on the back you can see the internals of the engine while it's running and it looks pretty cool the results from my test runs weren't too shocking with the bigger ball valve the engine was able to run at the higher rpm but with a shorter duration and with a smaller ball valve the engine was able to run for longer but with a lower rpm one of the major positives is that nothing broke during the testing are you sure about that and the engine still runs smoothly after a number of runs i still think i could squeeze more performance out of this engine but this project's been going on long enough so i think that's enough for now thank you for watching the video if you liked it consider giving it a like if you want to see more like this in the future maybe hit that subscribe button it's free free don't forget to leave any tips suggestions or anything you want to see in future videos in the comments down below that's it for me see you next time [Music] you

Channel: Kurzey

Views: 32,246

Keywords: 3d printed, engine, compressed air, piston, crankshaft, compressed air engine

Id: 7lyepd9qTVk

Length: 15min 47sec (947 seconds)

Published: Sun Aug 01 2021