Lego Pneumatic Engine

[Aleh]

I didn't catch where the grey tube goes?
And does the bottle has regural pressure or what??

[LegoEmbodiment]

18 hours ago, Aleh said:

I didn't catch where the grey tube goes?
And does the bottle has regural pressure or what??

The grey tube has a plug, but that tube is needed to connect it to an other cylinder. 

The bottle has no regular pressure, it's because the sleeve valve closes quickly and then the pressure goes down when the piston goes down. 

[Aleh]

5 hours ago, LegoEmbodiment said:

The grey tube has a plug, but that tube is needed to connect it to an other cylinder. 

The bottle has no regular pressure, it's because the sleeve valve closes quickly and then the pressure goes down when the piston goes down. 

Aahh, this does not even need a compressed air! Double cool! 

[2GodBDGlory]

By the way, in case anyone doesn't know, the valve used in the engine is known as a valve stem core (I think), and normally screws into the valves on car wheels. I imagine they can be bought at auto parts or tire stores. Also, ones from bicycles seem to have a different design, to my chagrin.

[LegoEmbodiment]

13 minutes ago, 2GodBDGlory said:

By the way, in case anyone doesn't know, the valve used in the engine is known as a valve stem core (I think), and normally screws into the valves on car wheels. I imagine they can be bought at auto parts or tire stores. Also, ones from bicycles seem to have a different design, to my chagrin.

It's all correct. 

[Aleh]

11 hours ago, 2GodBDGlory said:

By the way, in case anyone doesn't know, the valve used in the engine is known as a valve stem core (I think), and normally screws into the valves on car wheels. I imagine they can be bought at auto parts or tire stores. Also, ones from bicycles seem to have a different design, to my chagrin.

About bicycle wheel - it has two types of valves  - Schrader (thick one from auto) and Presta (Thin one).

[2GodBDGlory]

9 hours ago, Aleh said:

About bicycle wheel - it has two types of valves  - Schrader (thick one from auto) and Presta (Thin one).

Good point. Even the Schrader cores are different from carbone's, though, at least on the one I ripped apart. (I don't have the special screwdriver to remove it, but I was surprisingly able to unscrew it with my Swiss Army Knife tweezers)

[LegoEmbodiment]

 

[LegoEmbodiment]

YouTube: Remote Control V2 LPE Powered buggy with Flow Control System 

[2GodBDGlory]

I like your innovation in pneumatic engines! Good work!

[tibo_gosse]

I made a very powerfull and small v4 engine. I want to show you the result, tell me what you think of it.

 

[Gray Gear]

Very cool! I just wish there was a way to not have a pneumatic hoze coming out of the car...

[2GodBDGlory]

3 hours ago, Gray Gear said:

Very cool! I just wish there was a way to not have a pneumatic hoze coming out of the car...

I've always wondered if one could put a small spray can of compressed air into a model with a pneumatic engine, and then control the can's throttle with a remote-controlled motor. It would be fairly big, and potentially expensive, but it could work well provided pressure and run time were high enough.

[Gray Gear]

@2GodBDGlory there are these small preassurized co2 capsules, like this:

Edited December 15, 2021 by Gray Gear

[tibo_gosse]

But it's very hard an dangerous to use, because it's about 40bars. And even if it works, it would only be for a few minutes maybe.

For me the best solution seems to be the pneumatic hoze.

 

[Bluehose]

Niiiiiiice

[2GodBDGlory]

17 hours ago, Gray Gear said:

@2GodBDGlory there are these small preassurized co2 capsules, like this:

I've got myself an old aerosol can (air intake cleaner) and an automotive valve stem, and I'm thinking I might punch a hold in the bottom of the can, drill it out larger, drain out any fluids, and then insert the valve stem to (hopefully) make a refillable can of compressed air. Apparently puncturing these cans can be dangerous, though, so try it at your own risk while I try to come up with the safest way possible! (And after that, too)

It'll be interesting to see how it works, and especially how long it will last for. 

[tibo_gosse]

To have an idea of "how long it will last" I can give you my experience.

I have a compressor with a 2L Bottle, at 4 bar, with my V4, at full throttle, it last about 30 seconds, if I reduce the pressure at 1 bar to the engine, it can last 2 min, but at 1 bar there is not enough power to do somthing.

And I want to say that this engine is one of the best I have ever made,  it's not leaking, the pistons and the switches are exellent, this engine is very efficient.

(I m sorry, I m not very good in english so....)

[2GodBDGlory]

16 hours ago, tibo_gosse said:

To have an idea of "how long it will last" I can give you my experience.

I have a compressor with a 2L Bottle, at 4 bar, with my V4, at full throttle, it last about 30 seconds, if I reduce the pressure at 1 bar to the engine, it can last 2 min, but at 1 bar there is not enough power to do somthing.

I guess my only hope for a longer run time is pumping the air up to higher pressures, taking advantage of the can's metal construction

[tibo_gosse]

with : PV = nRT

In 2 liters at 4 bars, there is  9.5*10^(-3) mol

If you want the same quantity of material but in 200 ml ( like in a aerosol can ) you need a pressure of 39 bars.

Good luck, and be careful 

[nerdsforprez]

On 2/15/2021 at 7:03 PM, 2GodBDGlory said:

I've always wondered if one could put a small spray can of compressed air into a model with a pneumatic engine, and then control the can's throttle with a remote-controlled motor. It would be fairly big, and potentially expensive, but it could work well provided pressure and run time were high enough.

I did something similar to what you are talking about years ago.  Not exactly, but somewhat.  I don't think trying to fit a aerosol can with even more compressed air would be a good idea though.  Even though, like you can see here, traditional ways of storing air just don't lead to enough run time.  

Also, here is a video with using the small pneumatic cylinders instead of the large ones.  Less power, but much more run time.  THough I would argue it appears the power is even less than PF or PU.