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[图纸] 小型发动机图纸及制作

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发表于 2011-11-12 08:00:02 | 显示全部楼层 |阅读模式
This is a tiny I.C. engine that I just completed. I first saw this engine at the LeSueur, MN. Pioneer Power Days last summer. A gentleman by the name of Jim, from Des Moines, IA. Had a couple small engines that that were beautifully built and run like a dream. Jim and I have had many conversations since we first met and he has provided me with build information talked me through several problems I had completing this engine. Jim, I can't thank you enough.
This is the smallest I.C. Engine that I ever tackled.

It has a 3/8 dia. Bore and a 1/2 inch stroke. Getting two valves and a spark plug in that small area proved to be quite a challenge.

It was the first time I tried making a spark plug. The body was made from 12L14 with a Teflon insulator and .035 music wire electrode.

The fuel mixer was also quite small. The spray bar has .018 fuel inlet and a .020 cross hole. The needle is a .025 dia sewing needle.
 楼主| 发表于 2011-11-12 08:02:21 | 显示全部楼层
本帖最后由 jjlove 于 2011-11-12 08:03 编辑


Jim recommended using S/S Machine & Engineering for a  CDI unit for the electrical end. Knowing absolutely nothing about CDI units, I contacted Roy Sholl, owner/operator of SS. I have to say that I have never worked with any supplier that has been as patient and helpful as Roy. I highly recommend him for anyone needing an ignition system for their models.
The CDI unit is very small and I was able to conceal it in the Corian base I made for this engine. The unit puts out a good spark. I ended up using a Hall Effect for my ignition.

Had a few problems getting the engine to run and stay running. I used an O-ring on the piston. The valves sealed OK. It took several tries to get the intake spring pressure correct. Once it started it run pretty good, but after a short time it would quit. I would have to choke the heck out of it to get it started again. After several runs, it wouldn't even start. I replaced the O-ring and it took off again. Apparently the finish in the bore was too rough and would ware out the O-ring quite fast. I put a good finish in the bore and haven't had a problem since.

Tiny I.C. Notes -- rev B.pdf

1.03 MB, 下载次数: 1802

小型发动机图纸及制作

Tiny 1 Frame - rev B.pdf

120.65 KB, 下载次数: 1328

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Tiny 1A Crank Ret. -- rev B.pdf

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Tiny 2 Gas Tank -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:03:34 | 显示全部楼层
Thanks to everyone for the compliments and comments. It has really been a fun & satisfying project, however frustrating at times. Smaller isn't always better & easier.
The design is essentially a 1/2 scale of the Upshur horizontal but with a lot of changes.
I did redraw every detail prior to building the unit. The drawings are not professional or even up to industry standards. I merely draw them so I can understand them and assemble the engine on the computer before I cut steel. I will post them as soon as I can check them over and figure out how to post them as PDF files.
Chuck, to answer your question, I really haven't run the engine long enough to see how hot is really gets. It does warm up quite fast.
Steve, the spark plug has a 10-32 thread, which seems too large for the cylinder size, but I cheated a little. After the threaded portion I necked it down to 1/8 for the remainder. That was the only way I could fit the plug and two valves in 3/8 dia. The Teflon machined OK but it was difficult to press onto the metal housing. It was like pushing a noodle. The plug shown was too short and did not enter the cyclinder area. The one in the engine is a little longer.

Tiny 3 Cylinder -- rev B.pdf

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Tiny 4 Crank -- rev B.pdf

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Tiny 5 Flywheel -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:04:31 | 显示全部楼层
小型发动机图纸及制作

Tiny 6 Gears -- rev B.pdf

77.51 KB, 下载次数: 1035

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Tiny 7 Piston -- rev B.pdf

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Tiny 8 Con Rod -- rev C.pdf

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Tiny 9 Head -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:06:08 | 显示全部楼层
I just looked at the downloads. It looks like I made a real mess of things. They are all separate downloads and some do not have titles.
I was hoping to download enough prints so anyone who wanted could get started on their build while I finished the rest of the prints. Maybe it is best to remove the one that got loaded and wait until they are all completed. May take awhile.
It also appears that once I upload them I have no way to manage them.

Tiny 10 Valve Cutter -- rev B.pdf

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Tiny 11 Valve -- rev B.pdf

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Tiny 12 Spark Plug -- rev B.pdf

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Tiny 13 Spark Plug Asm -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:07:24 | 显示全部楼层
Gail, I think that is exactly what I was looking for. I have all the prints drawn but many of them have been altered so I can get certain dimensions that I need. I have a DRO on the mill and work from center point in all directions now & then. I will review & correct them so that others can use them. If I can post them like you have done, then when everyone is satisfied that all the necessary information is there, I can upload a complete file.

Thank you so much Gail. I think I have mentioned it before but I am much more comfortable with a Bridgeport than I am with a computer.

Right now it is cocktail hour for us oldtimers. Will post prints tomorrow.


* Tiny 14 Spray Bar -- rev B.pdf (89.42 KB - downloaded 286 times.)
* Tiny 15 Needle Asm -- rev B.pdf (66.8 KB - downloaded 271 times.)
* Tiny 16 Mixer Body -- rev B.pdf (94.23 KB - downloaded 287 times.)
* Tiny 17 Stand Off -- rev B.pdf (60.3 KB - downloaded 273 times.)

Tiny 14 Spray Bar -- rev B.pdf

93.36 KB, 下载次数: 963

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Tiny 15 Needle Asm -- rev B.pdf

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Tiny 16 Mixer Body -- rev B.pdf

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Tiny 17 Stand Off -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:08:03 | 显示全部楼层
Thanks to Gail, I am going to try to provide enough photos and prints to build the Tiny I.C. engine. The first PDF file is a series of written notes that may or may not help you. I'm sure many of you have your own way of attacking a project and this is just one way.
The first part is the frame. It is a fairly easy part to build and once it is done, you get the feeling you are well on your way.

Next is the combination base and gas tank.

The next part would be the cylinder. I have had good luck following the procedure for putting the cylinder sleeve into the hopper frame on several engines that I have built. It even works better on the larger bore sizes.

Tiny 18 Rocker Arm -- rev B.pdf

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Tiny 19 Linkage -- rev B.pdf

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Tiny 20 Cam Follower -- rev B.pdf

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 楼主| 发表于 2011-11-12 08:08:20 | 显示全部楼层
You might want to tackle the gears next. I suggest this in case you have to make or purchase any tools to get the job done.
The whole size and c-bore in the larger gear is up to your discretion. I happened to have some little shoulder screws on hand so I made the gear to fit. You may have to make your shoulder screw if you have none available.

The connecting rod is a little different than most because of the space available on this small engine. I made a horizontal clamp instead of a vertical one to reduce the size under the crank.

The head is probably the most difficult part on the engine. There is a lot to crowd into a small area.
There are a couple of set ups that are difficult to explain in words so I'll show some photos.
Set up for locating & drilling the spark plug hole.

Set up for locating, spot facing, drilling & tapping the spark plug hole.

This is what you should end up with.


 楼主| 发表于 2011-11-12 08:08:35 | 显示全部楼层
OK, found the old disk and reloaded the software for the scanner. Hopefully it will last long enough to complete this project.
These valves are probably as small as you will have to make for any engine. I cheated a little and used some hardened punch pins that we used to use for core pins in plastic molds. They have a 3/32 shank and a 60 degrees swaged head. The head had slight seams on the taper so I had to grind a smooth surface with my simulated tool post grinder. Also had to grind a groove for the retainer as they are too hard to drill cross holes in them.
You will probably be making your valves from scratch using drill rod.


While I had the compound set up at 30 degrees, I machined the valve seat cutter out of drill rod.
This insured that I had the same angle on the valves and valve seat.  George Britnell's post is a very good guide for making valve seat cutters.

Next is the spark plug. I was always intimidated at the thought of making a small spark plug, but after following some of the post on HMEM by more experienced builder than me, I decided to give it a try. It actually wasn't that bad.
I used 1/4 hex stock for the body, Teflon for the insulator, & .032 music wire for the electrode.
Because of the cylinder size I was very restricted to the spark plug size. I chose to use a 10-32 thread and then neck the rest of the body down to 1/8.
 楼主| 发表于 2011-11-12 08:08:47 | 显示全部楼层

Machining the Teflon with that small dia is kind of difficult. I decided to start by turning a dia. Down to 1/4" and drilling a .032 hole through it. Next I machine the brass ferrule & soldered a piece of music wire in it. By pressing the music wire into the Teflon it help stiffen the Teflon.
To provide additional support for machining I drilled a .032 hole in the center of a piece of 3/16 brass rod.  I then held the brass rod in the tail stock chuck. There was about .10 length of music wire sticking out of the Teflon that would stick into the brass rod and support the assembly, just like turning between center.

After turning the body and the insulator the pieces can be pressed together. The smaller .079 dia Teflon should just be a nice slip fit in the body. If it is too tight, it will just bunch up in the body.
Lastly is machining the overall length and finishing the electrode end. I machined about 1/32 off each side on the end of the spark plug down to the dia of the electrode. There is some Teflon left that you will have to remove with a knife. Final result is a surface gap spark plug.


Back again with a few prints. Getting close to the end. I have been getting some real nice comments on these posts and I thank all of you. I would like to make any necessary corrections on these prints before I put the entire package into one PDF file. I need some feedback from anyone who has found errors or missing information of the prints. You can post or PM any corrections.
The fuel mixer is a very critical part of this engine, and I guess for any engine. This one has some pretty small holes to drill so you might have to prepare for that if you don't have the drills, taps, & dies.
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