A SILENCER DEVICE FOR EXHAUSTS OF MOTORS AND SIMILAR, WITH ACOUSTIC INTERFERENCE

Abstract: The device reduces the intensity of noises with localized outlet like those present in the exhaust pipes of endothermic motors, making use of sound-interferences determined by an elastic vibration by means of springs (10) or (12) or (15) of a rigid rod (6) having its fulcrum in (11) and passing through coupled tubes (1) and (2). The acoustic waves spreading in the exhaust and acting onto blade (7) out of one piece with said rod (6) inside the exhaust pipe (1), determine the vibration of the corresponding blade (8) out of one piece with the opposite part of said rod (6) and housed in the coupled pipe (2) so as to generate vibrations in perfect phase opposition interfering at the exhaust pipe's outlet, thus anulling or strongly reducing the noise.

Description: "A silencer device for exhausts of motors and similar, with acoustic interference" The present invention concerns a silencer device for exhausts of motorcycles, vehicles, air conditioners, air compressors and all other acoustic pollution sources. Until today the attempt of reducing the noise, which is one of the most serious components of the pollution in the indu¬ strial society, has been develloped with sound-absorbing means suited for reducing the intensity thereof. In particular for what concerns the reduction of the noises produced by the exhausts of motors of any kind, the outlet gases are forced to pass through winding passages and hurt against absorbing walls which however do not determine a sound reduction level that makes the civic centers, the work- ing ambients and places like autodromes and the like more comfortable. It is the aim of the present invention to completely elimi¬ nate the noises produced by the exhausts of motors, condi- tioners, compressors and similar by means of a process dif¬ ferent that absorption. It is already known that the physical phenomenon of interfe¬ rence allows in case of overlaying of acoustic waves in phase opposition, to anul a sound with a "counter-sound", charac- terized in a phase-displacement corresponding to a displace¬ ment of wave length. It is the aim of the present invention to realize an active silencer device that will produce for each sound passing through the exhaust pipe of any kind of motor, a correspond¬ ing counter-sound in phase opposition that will be superimpos¬ ed to the primary sound in correspondence to the noise's out¬ let, thus anulling it. The evident advantage of the present invention consists in the capacity of the device to make any noise source with lo¬ calized outlet noiseless, without therefore causing any re¬ duction in the efficiency of the motor itself but, on the contrary, inproving the functioning of the same. The present invention will be explained more in detail here- inbelow relating to the enclosed drawings in which a prefer¬ red embodiment is shown. Figure 1 shows a vertical section of a silencer device for exhausts of motors and similar with acoustic inter¬ ference. Figure 2 shows an axonometric exploded view of the device according to figure 1. Figure 3 shows a scheme of a mechanical variant of the devi¬ ce according to the present invention. Figure 4 shows a scheme of a variant of the device according to the present invention provided with external springs. The figures show a silencer device for exhausts of motors and similar with acoustic interference, consisting of a pipe 1 with walls being insulating against heat and sounds with amianthus, that may be applied, in a well known manner, to exhaust pipes of any kind, or that may be obtained inside the end part of said pipes. To said first pipe 1 a second pipe 2 is applied parallel and out of one piece, being closed at the end of the se ispheri- cal cap 3 with hole(s) 4 for the air from the outside. Said parts 1 and 2 converge in the same outlet end 5 being preferably outwardly tapered. A main feature of the device according to the present inven- tion consists in the rigid rod 6 passing through an opening 11 provided in said parts 1 and 2, and provided with end blades 7 and 8 having its fulcrum on the spherical knot 9 or similar, placed in the point of contact of said parts of the pipes 1 and 2 and that will elastically vibrate due to the presence of springs or similar applied on both sides, under the impulse of the acoustic waves spreading in the exhausts in part 1 and acting onto blade 7 so that the corresponding blade 8 produces vibrations in the air entering pipe 2 through hole 4, in perfect phase opposition with respect to the exhaust waves. Infact, to each compression phase of said blade 7 an oppo¬ site phase of rarefaction of the coupled blade 8 corresponds and vice versa, so that blade 8 in turne produces a sound in phase opposition to the one spreading in the exhaust and act- ing on said balde 7. Said two composed sounds, or noises, now reach outlet end 5 overlapping and therefore reciprocally anulling themselves according to the aim set forth. For what concerns the variant according to figure 3, above mentioned springs 10 are replaced by an elastic blade 12 pre¬ ferably out of a double steel layer or similar, for making the vibration of said rigid rod 6 elastic in correspondence with each frequence of the sound wave spreading in the ex¬ haust and therefore in the part of pipe 1. In all variations the present invention provides a jet-break¬ er 13 fixed to the walls of pipe 1 by means of small bars 14 or similar, placed for exactly covering blade 7 and provid¬ ed with an aerodynamic shape such as to deviate the exhaust flow and to prevent said blade 7, even if always vibrating due to the resonance with the sound waves coupled to the exhaust, from getting inclined by the mechanical impact of the exhaust, improving the efficiency thereof. Should the temperature of the exhaust be such as to reduce the elasticity of the internal springs 10 or 12, the pre- sent invention provides, in a variant; that the vibrations of the rigid rod 6 be determinet, through a transversal rod 16, by helicoidal springs 15 or springs of any other kind housed outside pipes 1 and 2, as shown in figure 4.

Claims: CLAIMS 1. A silencer device for exhausts of motors and similar with acoustic interference, comprising means for generating a sound being in phase opposition to the one of the exhaust, and for the overlapping thereof at the outlet so as to de¬ termine the reciprocal annulment of the two sounds, cha¬ racterized in: - a part of pipe (1) with walls insulating from heat and from sounds, applied to the exhaust pipes or obtained inside the end part of said pipes; - a pipe (2),closed at the end thereof by a semispherical cap (3 with hole(s) for the inlet of air from the out¬ side, coupled in parallel to said part(1)and converg- ing in the same outlet end (5); - two blades (7) and (8), bound one to the other by a ri¬ gid rod (6) passing through an opening (11) provided in said parts (1) and (2) and having its fulcrum on the spherical knot (9) placed at the contact point of said pipe parts (1) and (2) and that will elastically vibrate due to the presence of springs (10) or similar applied to both sides under the impulse of the acoustic waves spreading in the exhaust of part (1) and acting onto blade (7), so that the corresponding blade (8) causes vibrations in the air entering into pipe (2) through hole (4), in perfect phase opposition with respect to the waves of the exhaust. 2. A silencer device according to claim 1 characterized in that said springs (10) are replaced by an elastic blade (12) preferably out of a double steel layer or similar, that will make the vibration of said rigid rod (6) elastic. 3. A silencer device according to claims 1 and 2 characte¬ rized in a jet-breaker (13) fixed to the walls of tube (1) by means of small bars (14) or similar, placed for exactly covering blade (7), and being provided with an aerodynamic shape for the deviation of the exhaust's flow. 4. A silencer device according to claim 1 characterized in that helicoidal springs (15) or similar are placed insi- de pipes (1) and (2) so as to determine, by means of a transversal rod (16), the vibrations of the rigid rod (6).

Inventors: MASCIOLI ALESSANDRO, MASCIOLI, ALESSANDRO
Applicants: MASCIOLI ALESSANDRO, MASCIOLI, ALESSANDRO
Application year: 1988
Main classification: F01N1
IPC codes: F01N1, F01N7