Solenoid engine Build

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foozer:
Ages ago helped the boy build a gadget similar for his school science project. Do 'member timing was fun. Energized the coil and let it lock the piston in place. Used that to set rod length so crank was at the qtr over position (90 with BDC as 0) We set the switch to energize coil a tad after BDC and release before crank reached the 90 degree point. Was a simple gizmo and IIRC it ran the best with just the tiniest bump of juice to the coil.

Robert

cfellows:
Al, I think I see what you are trying to do. I saw a similar magnetic engine in an old Popular Mechanics (or Popular Science) magazine. It can be done if your piston (plunger) is exactly at the half way point through the coil when the crankshaft is at 90 degrees and 270 degrees. In other words, at top dead center and bottom dead center, the piston must be past the center of the coil by an equal amount. The coil coil should be energized at both top dead center and bottom dead center, then turned off when the piston is close to the center of the coil in either direction.

I doubt this form of double acting piston really gains anything in speed or efficiency over a single acting piston which is energized for the full stroke with the piston travel reaching the center of the coil at or before top dead center.

Chuck

Bernd:
My 2¢ Al, I think you'll need two selenoids to make it work. I'll try to get a C-of-C together and post it later.

Bernd

foozer:
One thing that I haven't seen in this build and have assumed you've tested it.

When you energize the coil does it center the piston in the bore or draw it to one end, shape seems to indicate that it pulls the piston all the way to the end of the stroke. If thats the case dont think a double action will fly. A pulse of juice at any point from BDC to TDC for a duration of just a few degrees should get it going

CallMeAl:
Well I finally got it to run! :ddb:

Today I did some more fiddling with the eccentric timing, bump cams positioning, and the piston rod length on the cross head and what do you know it started running.

I guess I wasn't so crazy after all and with all the encouragement to not give up on this from the members of Mad Modder I accomplished what I hoped.

You can have a double acting solenoid if you position the armature correctly when the electrical pule is applied. Since the solenoid works by drawing a iron armature in to the center of the coils magnetic field, if you do that at the same position at each end if the coil and time your switch correctly the coil should pull in on the armature from each end on the coil.

This switching has to be done just after TDC and BDC as several posters mentioned. Part of my problem was I was timed to actuate the switches a both ends of the stroke just prior to those points. You can get away with that on a IC engine because you're compressing a gas but not on a solenoid!

Another thing that was causing me grief was the solenoid I chose to use has a very narrow coil width since a hydraulic vale spool only needs to travel about .250 to .375 inch so it only needs to pull the armature that distance and it is spring offset the other direction. Here is cross section off the solenoid I used.

I believe this made the setting of the timing more critical since my total stroke is 1.500 inches. Also, a rotatory cam would probably be better than my bum cams since you could better control the on time of the coil for more power.

Anyway, thanks for all the replies, suggestions, and encouragement. :bow: I probably would have given up on it. It's still not completely finished. I want make wood base, mount a on/off switch, and fix the wobble in the flywheel among other things.
Also, I don't need the governor - it doesn't run that fast. ::) The coil heats up quite fast so running time may only be about 3 - 4 minutes.

Here is a video of actually running:

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