VALVE INSTEAD OF THE SPOOLEvery modeller wants the motor on his model, and starts with one pull, and worked “like clockwork.” But the fine-tuning motor is not only extremely high precision. It requires not only considerable knowledge, but also certain abilities. Because the manufacture and fitting of any part or Assembly is unthinkable without its “tricks”. How many cares one brings suction system! The variety of constructive decisions shows, so far not found the optimal variant.

Lately increasingly turning to valve designs. And in fact, this inlet of the working mixture in the crankcase has a number of advantages over conventional Zolotnik suction system. First of all, the valve works automatically. No need to pick up the opening phase of the valve. But often this selection is done intuitively, or take data from other engines, which showed good results. And that absorption phase is determined (with an unknown degree of accuracy) only one mode and without the need to change them even for the same engines with different mechanical condition. The valve itself adapts to engine speed, providing good start-up and output for maximum power with a resonant exhaust pipe. Additionally, there are friction losses and valve site, which is not so small.
Valve, which will be discussed, is mounted in the rear wall of the engine working volume of 2.5 cm3. The casing is made from a material D16T. Seat sizes a and b are performed but the existing sump. To reduce podpolnogo volume, it is advisable to cut the leash of the shaft for driving the spool, or to make the wall of the engine with an annular groove under the leash. The channel under the core rastaquouere on a milling machine or lathe with a specially made gon. Coming into the crankcase hole is brought to the rectangular duct work.
The valve core is made with the diffuser of the carburettor. Material — D16T or V95. Bifurcated channel closed petals done: drilled the center hole to the future jumper, then milled beveled plane. To “improve” it, epilep the bridge to diamond-shaped cross-section. Don’t forget to mark the edge of the future channel. It should be no closer than 1.5 mm from the boundaries of the plane on which to lay the petals.
Now it is over by the petals. The best material for them is leaf spring steel of a thickness of 0.03 mm. Can be used titanium foil of the same thickness. Cut them out with scissors valid, but it is better to apply the etching and subsequent Stripping of the edges on a grinding stone.
Control valve
Control valve:
1 — housing, 2 — insert, 3 — gasket, 4 — petal, 5 — core, 6 — nozzle.
An important detail of the valve — shaped insert. She has two tasks. The first is to reduce the volume of the crankcase. The second is to set fold plates form conducive to their quick return to the closed position and a sharp cut off of flow of the mixture. The insert gives the opportunity to use foil, which you cannot do with the free limb. And the thickness is the stiffness of the petals, their weight, inertness and clarity the valve is open. The thin material allows to open all the fairly wide cross-section of the inlet channel, which is not previously used freely folded plates.
The best material inserts — nylon. It is quite flexible and forms a wear small fibers, as the PCB. Carved from several pieces, drilled on the axis of the technological hole Ø 7 mm. It allows to process the files channel insert, and it makes sense for different parts to make different curves of the surfaces, which lie folded petals. Choosing insert, you can achieve perfect operation of the entire valve. On the same surface, it is useful to perform a series of grooves or holes, to avoid adhesion of the petals. Her profile should be close to the parabola, which will give the greatest closing speed of the valve.
During Assembly until the desired core position by selecting the thickness of the strip. Better if his jumper will be in the plane of symmetry of the engine. This will ensure efficient cooling of the piston by both parts of the fresh mixture jet.

Recommend to read

    In the journal "modelist-Konstruktor" No. 4'2003 was a good publication about the interesting developments of the members of the club of Tambov veloturistov: different models for every...
    When working with wood panels, sheets of particle Board or plywood is often necessary to sand narrow frontal and lateral plane. Usually pick up the sandpaper and get to work: in the best...