RU195483U1 - Muffler - Google Patents

Abstract

The invention relates to functional elements of exhaust systems of internal combustion engines (ICE) of vehicles. The muffler has a cylindrical body 1 with end caps 2, an axial perforated pipe 4 is installed inside the body. The volume between the body 1 and the axial pipe 4 is divided into expansion chambers 6 - two and more. The cameras are not packed. Between adjacent chambers 6 transverse partitions are installed, having the form of a ring with flanges along the inner hole and along the outer contour. The holes in the transverse partition are punctured without loss of material with the formation of serrated edges. The holes in the transverse partition can be evenly distributed around the circumference. Achievable technical result is an increase in the efficiency of damping the sound wave in a wide frequency range with the exception of the possibility of resonance oscillations in the silencer chambers while decrease in hydraulic resistance.

Description

The utility model relates to the functional elements of exhaust systems of internal combustion engines (ICE) of vehicles, and can also be used in stationary power plants equipped with ICE, in other sources of pulsating gas flows and exhaust paths.

In the context of this application, the term "silencer" is used in the broadest sense - as a device that reduces the transmission of sound through the channel, without interfering with the transfer of the medium, that is, not only in relation to such a functional element as the main silencer, designed to completely dampen the sound of the system exhaust emissions, but also for other silencers, such as:

- a resonator (auxiliary silencer) designed to suppress peak low-frequency sounds that occur when opening the exhaust valves of the internal combustion engine, as well as to compensate for resonant vibrations that occur during alternate detonation of the fuel mixture;

- flame arrester - an additional resonator;

- Stronger (exhaust pipe silencer), designed to optimize the operation of the exhaust system, accelerate and twist the movement of exhaust gases and to create an obstacle to the pressure of the counterflow. Stronger is not directly responsible for the compensation of sound waves, however, when a sound wave enters it, it is subjected to additional attenuation.

In modern designs of silencers of automobile ICEs, sound-absorbing chamber packings with fibrous materials are widely used to improve the sound suppression of an expansion cylindrical chamber with internal perforated pipes. As an example, we can cite the design of the silencer of automobile ICE engines, described in the utility model patent No. 15494, publ. 10/20/2000. The silencer contains a housing with an axial perforated pipe installed in it, surrounded by a composite sound-absorbing material. In patent No. 15494 it is noted that glass fiber and / or basalt fiber and / or metal fiber and / or glass canvas and / or glass mesh can be used as a composite sound-absorbing material. The perforated partitions installed between the axial perforated pipe and the casing divide the internal volume into chambers. Partitions also help reduce sound levels.

Currently, most companies producing cars use silencers, in the construction of which, between the body and the axial perforated tube, a packing of mineral, often basalt fiber, so-called dissipative silencers is used. With sufficiently high heat-resistant and sound-absorbing characteristics, such a fibrous-porous sound-absorbing packing weakens unwanted defective resonant high-frequency “whistles” of the muffler. However, this design has a number of significant drawbacks, the main of which are as follows:

- the packing made of fibrous mineral material actively absorbs and accumulates chemically aggressive condensate contained in the exhaust gases in the cavity, which causes accelerated internal corrosion of the walls and partitions of the silencer body, significantly reducing its life. This forces the use of expensive stainless chrome-nickel steels for the manufacture of the body and axial pipe,

- filling the expansion chambers of the silencer with a fibrous noise-absorbing packing causes some loss in the efficiency of damping low-frequency noise due to the partial loss of the volume of the cavity of the expansion chamber filling the packing,

- during long-term operation of the device, the porosity of the fibrous packing of the chamber decreases due to the accumulated effect of carbon particles (soot) and liquid condensate (“coking” of the pores), which leads to a deterioration in the sound-absorbing characteristics of the fibrous packing and a corresponding decrease in the sound-damping ability of the silencer as a whole;

- engine operation in forced modes leads to melting and sintering of the mineral filler and muffler failure;

- the use of mats from mineral fine fibers in the technology of manufacturing silencers is associated with harmful production conditions due to the possible ingress of small particles of fibers through the respiratory system into the human body.

There are known designs of silencers, devoid of the above disadvantages due to the partial or complete refusal to use gaskets made of mineral filler - the so-called resonant and reflective silencers (in the terminology of GOST 31328-2006 Noise. Guidance on reducing noise by silencers).

In the patent for utility model No. 185332, publ. 11/30/2018 a silencer design is described, the casing of which is divided by internal partitions into the inlet, center and outlet expansion chambers. The inlet chamber is completely filled with sound-absorbing packing (basalt fiber). The pipe is installed in the indicated partitions along the axis of the casing and has in the central chambers narrowing the passage section, redirecting the flow of exhaust gases. Groups of holes are made in the partitions, organizing the movement of the specified flow inside the housing. In the partition between the inlet chamber, completely filled with sound-absorbing packing, and the central chamber adjacent to it, two groups of holes are arranged symmetrically with respect to the axis of the housing. In the remaining internal partitions, one group of holes is made, alternately located on opposite sides relative to the axis of the housing. The noise energy of the exhaust gases of an internal combustion engine is primarily absorbed by the packing in the inlet chamber. Sound waves that enter the central chambers that are not filled with fiber and pass through groups of holes are significantly attenuated due to interference with reflected waves arising from collisions with dull sections of partitions. The design can significantly reduce the exhaust noise of the internal combustion engine’s exhaust gases, however, due to the presence of an inlet chamber filled with sound-absorbing mineral packing, it retains the disadvantages inherent in dissipative structures.

As a prototype, an automobile muffler was selected, described in the patent for utility model No. 63454, publ. 05/27/2007. An automobile muffler comprises a cylindrical body with end walls, coaxial inlet and outlet pipes, internal transverse partitions with crosswise cuts in perforation. As described in patent No. 63454, at the entrance of exhaust gases through the inlet pipe, isentropic expansion occurs in the inlet section and weak shock waves are formed, which, when passing through the perforated baffle, reduce their parameters (pressure, velocity head) due to interference of gas flows and vortex formation at the exit them from cross-shaped channels. The flow of gases passing through each of the subsequent perforated partitions weakens, which enhances the effect of sound absorption. The muffler of the prototype does not provide for the use of sound-absorbing packing, that is, it does not have the corresponding disadvantages described above. However, the construction No. 63454 described in the patent cannot provide sufficiently effective noise absorption, since the silencer does not have separate expansion chambers that allow damping the pressure fluctuations of the exhaust gases, and all chambers are actually classical resonator chambers, each of which will have its own fundamental frequency and overtones, generating spurious sound vibrations at different engine speeds. In addition, exhaust gases passing through rather large cruciform slots create aerodynamic vortices at the edges of the slots, which leads to the subsequent generation of sound waves of an unpredictable frequency and the appearance of resonant vibrations in the silencer chambers at different frequencies. It should also be noted that the entire volume of exhaust gases passes through a series of partitions with crosswise slots. This leads to an increase in hydraulic resistance and an increase in outlet temperature.

The utility model is based on the task of expanding the arsenal of tools and creating a new silencer design. Achievable technical result is an increase in the efficiency of damping a sound wave in a wide frequency range with the exception of the possibility of resonance oscillations in the silencer chambers, while reducing hydraulic resistance.

The problem is solved in that the claimed silencer has a cylindrical body with end caps. A perforated axial tube is installed inside the housing, the volume between the housing and the axial pipe is divided into expansion chambers that are free of packing. Between adjacent chambers, a transverse partition is installed, having the form of a ring with flanges along the inner hole and along the outer contour; holes are made in the partition by puncture without loss of material with the formation of serrated edges.

The holes in the partition can be evenly distributed around the circumference.

The silencer may have at least two expansion chambers.

In order to better demonstrate the distinctive features of the utility model, as an example, which does not have any restrictive character, the variants of specific implementation are described below with reference to mufflers of various designs. Examples of implementation are illustrated by the figures of the drawings, which schematically represent the structure:

FIG. 1 - collector arrester, FIG. 2 - flame arrester, FIG. 3 - resonator, FIG. 4 - Stronger, FIG. 5 - a partition between cameras.

The silencer has a cylindrical housing 1. The cylinder may be circular or elliptical. The body length is from 80 mm to 800 mm, the diameter is from 75 mm to 200 mm. Case 1 to improve the performance of damping sound on powerful ICE can be two-layer. The housing is closed by end caps, which can be flat (caps 2), conical (caps 3 in Fig. 1), rounded. The covers may be rolled, welded, or integral with the housing, as shown in FIG. 4. Inside the housing 1, a perforated tube is installed along its axis 4. Perforation holes made in the axial tube 4 can have a rounded shape (punching holes), but slotted perforation with blinds (aerodynamic visors) can also be used. The degree of perforation can be from 15% to 34%. The perforated axial tube 4 can be connected to the inlet and outlet pipe (see Fig. 4).

Between the housing 1 and the axial pipe 4 there is a transverse partition 5 dividing the volume into expansion chambers 6. The partition 5 may be several - two or more, thus, the structure may have two (Fig. 1) or more expansion chambers 6. The chambers 6 are not have gaskets (filler), their length varies from 40 mm to 250 mm.

The partition 5 has the shape of a ring with a flange 7 on the outer contour in contact with the silencer body 1, and a flange 8 on the inner hole in contact with the axial tube 4. The partition is fixed by welding.

In the partition 5 holes are made by puncture. The holes can be arranged in a circle. When performing a puncture, plastic deformation of the septum material occurs with the formation of cones, the vertices of which break during further deformation and, in contrast to round calibrated holes, holes with jagged edges 9 are formed.

The operation of the silencer is based on the principle of destructive interference of sound waves, according to which the conditions for superposition of sound waves are created in the chambers of the device. The partition serves as a reflector, and the presence of protruding notches at the edges of the openings of the partitions contributes to the "crushing" of the waves, a change in their frequency parameters and a multiple change in directionality. As a result of mixing the primary sound waves reflected from the plane of the septum and from the protrusions with notches, weakening of the resulting acoustic wave is achieved. Sound passing through each of the subsequent perforated partitions weakens, which enhances the effect of sound absorption. In addition, such a "crushing" eliminates the occurrence of resonant oscillations. Unlike the prototype, in which the entire volume of exhaust gas passes through the openings in the partitions, in the claimed utility model, the main gas flow passes through the pipe 4. That is, the partitions do not introduce a significant increase in hydraulic resistance.

Claims (4)

1. A silencer, characterized in that it has a cylindrical body with end caps, an axial perforated pipe is installed inside the body, the volume between the body and the axial pipe is divided into expansion chambers free of packing, between the adjacent expansion chambers there is a transverse partition in the form of a ring with flanges along the inner hole and along the outer contour, in the transverse partition, holes are made by puncture without loss of material with the formation of serrated edges. 2. A muffler according to claim 1, characterized in that the openings in the transverse partition are evenly distributed around the circumference. 3. The muffler according to claim 1 or 2, characterized in that it has two expansion chambers. 4. The silencer according to claim 1 or 2, characterized in that it has three expansion chambers.

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