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| A little Sleeve Valve Engine |
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| Joachim Steinke:
Hi to all, today I want to give you a first survey about my actual project. I aim to update this report from time to time, but not being a native speaker, writing relatively elaborated posts in English takes a lot more time for me than the activities in my German forums. And for the rest, a little time has to be left for machining all that things….ha ha ha….. So I hope you understand if continuance might come sparsely Building a miniature 4 stroke engine was on top of my to do list for a long time and in the last weeks I finitely designed the plans for a little 4.1 ccm motor. For me such a project has to have always a little thrill in it….ha ha ha…. so, to make things more complicated I choose a special design of charge changing. The engine will operate with a sleeve valve system, I think most people here would know this type of timing from the famous Bristol Airplanes build around the time of WW II. This type of engines had been already build in perfect miniatures from such experts as for example Brian Perkins with his 9 cylinder Aquillia and Tom Pasco with a 3 cylinder radial of own design. That’s a class of craftsmanship I am far away from, so I keep it simple start my first engine with a single cylinder type following my own design and my limited abilities. The basics are: stroke 16mm, bore 18mm, capacity 4.1ccm, compression ratio 6:1, spark plug ignition via Hall Sensor module, lubrication by gear oil pump, air cooling of cylinder and head. Over all sizes engine block: width 39mm, length 54mm and height 90mm. And here are some of the now completed drawings: This is a section from the right side And some details of the inner structure The oil pump And the oil distribution system The material composition of the stroke garniture is: piston, head, outer cylinder and piston rings are made from spheroidal graphite cast iron (GGG60) and the moving sleeve from high strength free cutting steel (ETG100), the crank- and camshaft are also machined from this steel. The engine block, the connecting rod and most of the other parts will be made from aluminium 7075 and the bush bearings will be made of bronze. End of Part one |
| Joachim Steinke:
Part Two The sleeve valve or otherwise said the cylinder sleeve is driven by a little ball of hardened steel sliding in a hardened cylinder which is mounted in the camshaft gear wheel. Here is a more detailed graphic of the port function: For a convenient check of the pre calculated in- and outlet port timing, which follows an elliptical curve on the circumference of the cylinder, I made an CAD animation of the involved component, you might take a look at a little sample video here, things become a lot more obvious then: http://pl-hi.de/JST/SLVE/SLVE_PORTS_02.wmv I just began the machining, so my progress is not that far. To get “warm” with the project I started with the carburettor. End of part two |
| Joachim Steinke:
Part three In between I completed the gear wheels, they are made of steel with modul 0.5 dimensions. And as I will solder them on there shafts it’s better to have a running test before getting an imprecise disaster when it’s too late, but all seems good so far. This sort of testing on the milling machine is a good method for measuring the very true distance of the axle-base too, you don’t have to rely on pure calculations and can judge the last hundreds of a millimetre from the running sound. The next part I wanted to clarify was if my design of the ignition system will work proper enough, for that circumstance would determine the further design of the engines blocks front section. The dimensions in front of the camshaft are really small and I wanted to place the magnet for the Hall Sensor in the front cover of the camshaft bearing. So the diameter of the revolving disk with the 2x4mm neodym magnet is only 9.5mm. An easy way to find out if the sensor will work through a 0.5mm wall of aluminium and if the triggering will do a precision angle repetition on such a small revolver is to ( I think you guess it…) make the next little running test…….ha ha ha…. But at last my doubts where unnecessary, the trigger works well with an 1mm aluminium sheet holding in the gap between sensor and magnet, the overall distance between the parts can have an amount of more than 3.5mm before the trigger “looses contact”. And the small diameter has no bad influence on the precision of the trigger point, I tested this on the lathe with a mark on the lathe chuck, very reliable results. So work can proceed, let’s see how it will go….. Good night from Achim |
| gbritnell:
Excellent work on your engine so far. I'm glad to hear your findings with the Hall sensor. I'm going to be using one in my current project and I was trying to keep my spacing down to within .035, .89mm. Now I won't have to be so critical with my dimensions. George |
| dsquire:
Achim Wow is about all that I can say for starters. I definitely am going to be watching for every new installment as you have time to post them. The drawings that you have made are great. It looks like you have a good start on it with the Carb and the gears already done. :ddb: :ddb: Don't worry about your English, there is nothing wrong with it. I'm just glad that I don't have to reply in German. :lol: :lol: Cheers :beer: Don |
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