THE SILENCER IN THE MUFFLER

MUFFLER SILENCERThe problem of noise of operation of internal combustion engines exist in all types of modeling. The modelers of the upper boundary of the acceptable level of noise has long been accepted 80 dB (when exceeding this value the result immediately canceled) have increasingly measured the noise of the flying machines, especially RC, are cases of control “of holosystolic” of micromachines and the competition of avtomodelistov. Performance requirements for noise suppression tougher every year, probably close to the time when the point of maximum noise will be introduced in the competition rules for all classes.
But now most of the serial motors if any, and is supplied with silencer, only for the conformity of the product vague modern rules clearly talking about the need for a muffler and not a word about its effectiveness. Serial muffler the scheme closed empty volume with inlet and outlet nozzles considerable section. In this embodiment, the device is able at best only to the suppression of a narrow band of a broad frequency spectrum of the exhaust noise.
 
Engine muffler
Engine muffler “rainbow-7” after modifications:
 
1 — housing of the main muffler, 2 — plate lamella muffler (stainless steel 0.3 mm thick), 3 — stopper, 4 — end plate lamella muffler (stainless steel 0.8 mm thick, holes for the passage of gases does not have), 5 — washers-spacers (any metal, thickness 0,4—0,5 mm), 6 — output pipe (for installation of lamella muffler to Shine with case), 7 — extra long M3 screws, 8 — strip gaskets (paronite or PTFE sheet, to put to seal the joint and reduce heat transfer from the muffler to the engine crankcase), 9 — engine.

 
However, there is an interesting method that allows at minimal cost of materials and labor to transform the classic muffler effective means of dealing with exhaust noise. This… placement in the cavity of the second muffler! A similar technique based on the creation of a labyrinth of cocoa, known in the practice of modeling, but in all cases the decision was a compromise. Had to find a “Golden mean” between the permissible reduction power and the required noise reduction. At the expense of combining the two single-purpose devices could radically improve jamming a wide spectrum of sound with minimal power loss.
 
A device for proscenia round holes in sheet metal
Device for proscenia round holes in sheet metal:
1 — punch (steel hardened), 2 — bolt M4, 3 — plate stock, 4 — ring knife (steel hardened), 5 — M4 nut.

 
The principle of refinement is clear from the drawings. Inside the regular muffler on the elongated bolts mounting the muffler to the engine is a set of consecutive round washers-spacers and thin plates. Structurally, the insertion repeats the device proposed by the modelers 15 years ago the American firm “Dubro”. Such a silencer, despite all the advantages over bulky, not found proper distribution. Most likely athletes were not satisfied with the wide spray used oil under the informal direction of the exhaust and the tendency of the engine to overheat when working with such a device at extremely high speed. In ordinary circumstances the muffler from the plates with a motor of 10 cm3 were given two times smaller reset speed
the same efficiency that classic volume option. For specific conditions device characteristics can be easily pick up by changing the number of washers and plates. The principle of operation was based on the fragmentation of the jet exhaust on a lot of small, malointeresny gas streams.
 
Arrangement of lamella in the amount of muffler muffler engine
The scheme of installation of lamella muffler volume silencer engine “Talka-7”
 
Particularly valuable in the muffler “Dubro” can be considered a minimal restriction of exhaust. This property allowed us to establish a set of plates inside the main volume of the muffler “Rainbow-7”, almost no impact on power data of the engine itself. “Rainbow 7” was chosen for the experiments as the most massive flight micromotor, and have developed Srebrenica. However, testing of a similar system in conjunction with the “clean-up day-7” showed the tendency of the engine to overheat throughout the operating speed range. Therefore, given such an option, when plates are placed at the incoming tangentially into the cavity of the muffler pipe.
 
A typical muffler company
Standard muffler company “Dubro”
1 — set of records (for radioprotecao engine working volume of 10 cm3 optimum number — 8), 2 — adapter-adapter to the exhaust pipe of the engine crankcase

 
Such a scheme is dual muffler can be recommended for engines up to 10 cm3, working even at high rpm. The important thing is to find the optimal number of washers and plates. In any case, the last contour must overlap the outlines of the hole of the exhaust pipe at least 3 mm around the perimeter.
 
V. CHIBISOV, engineer

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