RU55037U1 - MULTI-CAMERA NOISE MUFFLER OF INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

The utility model relates to mechanical engineering, in particular engine manufacturing, and in particular to multi-chamber, in particular, three-chamber silencers of exhaust noise of internal combustion engines. The muffler contains a cylindrical body with end walls, in which three chambers are formed by transverse perforated walls, an inlet and an outlet pipe, one of which is located coaxially to the body, while the cavity of the pipes are connected to the cavities of the respective chambers through their open sections and through perforated sections. A distinctive feature is that in the cavity of the muffler one inlet and two exhaust chambers are formed, the lengths of which, respectively, correspond as 3/8 ± 0.01: 2/8 ± 0.01: 3/8 ± 0.01 of the full length the silencer body, the inlet pipe is fixed on the end wall of the exhaust chamber, made rectilinear, located axially to the axis of the silencer body, its open section and the through perforated section are located inside the cavity of the intake chamber receiving exhaust gases, while the total passage area of the open section of the inlet of the nozzle is commensurate with the total area of the through holes of the nozzle perforation section, in addition, the open section of the nozzle is located at a distance from the transverse perforated partition that limits the inlet chamber equal to half its length, minus 0.2 ... 0.4 of the inner diameter -D - its cross section, the exhaust pipe is located coaxially to the housing, mounted on the end wall of the inlet chamber, its through perforated section and an open cut, respectively, are placed in the chambers organizing the exhaust gas and having lengths of 2/8 and 3/8 of the total length of the muffler, while

a through perforated section of the nozzle is placed between the transverse perforated partitions, on both sides of the middle of the chamber formed between them, symmetrically to the median plane perpendicular to the longitudinal axis of the silencer body, and its open section is placed inside the adjacent chamber at a distance from the transverse partition equal to half the length the chamber in which it is located, minus 0.2 ... 0.4 of the internal diameter -D- of its cross section, in addition, the total area of the passage section of the open outlet of the nozzle is commensurate with the total area of the through holes of the nozzle perforation section, the total area of the perforation holes in the partition restricting the inlet chamber is at least twice the total area of the perforation holes in the partition separating the outlet chambers, and the total area of the holes of the perforated section of the outlet nozzle and the perforation holes in the partition located in the exhaust chambers, not less than the total area of the perforation holes in the partition bounding the inlet chamber y. An example of a specific design of a utility model is given. Thanks to the use of the utility model, it becomes possible, with low production costs, to quickly learn a new, more efficient and better design of the exhaust silencer, acceptable for mass use in cars.

Description

The utility model relates to mechanical engineering, in particular engine manufacturing, and in particular to multi-chamber, in particular, three-chamber silencers of exhaust noise of internal combustion engines.

When the chamber muffler is operating in the place of expansion of the gas pipeline (that is, in the place where the chamber itself appears), an abruptly increased wave impedance is created - the “wave plug”, which in certain frequency ranges of the sound spectrum prevents the unhindered passage of sound through the muffler without noticeable attenuation, i.e. . provides a reduction in the level of acoustic energy emitted into the environment. In such a design of the muffler (such as a central expansion chamber), there is a predetermined cutoff frequency, starting only with which the muffler starts to work effectively (to drown out noise). At the same time, the damping characteristic of such a silencer is not an ascending inclined line, indicating an increase in the damping of acoustic energy with an increase in the frequency of the exhaust sound spectrum, but a curve, both with pronounced damping maxima in individual frequency ranges and pronounced “dips” "on individual discrete frequencies, or frequency bands in the damping characteristic. In some cases, at the frequencies of “dips” in the damping characteristic, not only zero damping of noise is observed, but even some amplification of exhaust noise at these frequencies.

It is these numerous “dips” that are a characteristic “acoustic defect” in the design of chamber silencers. The frequencies at which the indicated “dips” are observed correspond to the frequencies of multiple harmonics of the half-lengths of the waves that fit into the three-dimensional space of the expansion chamber of the muffler between the opposite rigid walls of the muffler chamber. To reduce the number of such dips (to minimize them), various structural elements are used in the silencers, for example, the internal introduction of sections of the gas pipe nozzles into the cavity of the silencer chamber in areas where these multiple half-long harmonics will not be excited, or, if excited, will not be output ( transmitted) from the cavity of the chamber further along the exhaust route of the gas pipeline into the environment. Such zones of exclusion (significant attenuation) of the excitation or energy transfer of the lower eigenmodes of the camera are the nodes (minima) of the sound pressure oscillations distributed over the three-dimensional space of the camera on these eigenmodes.

The principle of attenuation of the excitation and / or transmission of sound energy of the lower eigen resonance modes from the chamber cavity to the gas pipeline is implemented in the well-known single-chamber exhaust silencer for an internal combustion engine, USSR author's certificate No. 1092290, MKI F 01 N 1/00, BI No. 18/84, containing at least one cylindrical chamber with end walls and coaxial nozzles. A distinctive feature of the well-known muffler is that to increase the acoustic efficiency of noise damping by the expansion chamber, while achieving low hydrodynamic drags, dynamic (acoustic) sections of the inlet and outlet pipes of the chamber (i.e., conditionally elongated by 0.2 ... 0, 4D from its static geometric position, due to the attached mass of the oscillating gas at the end sections of the pipes, where D is the diameter of the passage section of the corresponding pipe) are placed in the nodal zones of lower intrinsic resonant longitudinal forms (first and second) of gas volume oscillations in the silencer chamber, i.e. realized along the length of the expansion chamber, in areas where the sound pressure value on the specified acoustic mode is close to zero, which prevents (significantly weakens) the further transmission of sound energy of these forms (modes) of vibrations by the external end section of the outlet pipe into the environment.

Such a design of a well-known muffler in some cases fits well, in particular, in the concept of sports cars, some stationary power plants with a fairly limited low noise suppression. However, its acoustic efficiency is clearly not enough for mass-produced cars, since it imposes significantly more stringent requirements of national and international standards on the maximum permissible value of the levels of external and internal noise of vehicles that protect the environment from excessive acoustic pollution.

Further improvement of the considered type of silencer is the design of a multi-chamber silencer described in USSR author's certificate No. 1420193, MKI F 01 N 1/00, BI No. 32/88 (or for more details see SN Volgin and others. Color illustrated album. Cars VAZ-2110, VAZ-2111, VAZ-2112 and their modifications. Moscow, "Third Rome", 1998, p.30-31), which has a significantly higher efficiency of damping the noise of the exhaust of an internal combustion engine, both in magnitude and more a wide frequency range of the muffler band, which, in particular, in The total time is used in a number of models of cars of serial production of AvtoVAZ OJSC. The above silencer for the exhaust of an internal combustion engine is three-chamber, contains a housing with end walls and coaxial inlet and outlet pipes, the dynamic sections of the latter being placed inside the central chamber of the housing. The silencer housing is oval and provided with at least one transverse partition to form chambers with end walls. One of the chambers (central) is made longer, its length is equal to the length of the larger axis of the body oval. The internal sections of the nozzles are placed in one of the chambers and are located at a distance of 1 / 4L from the end walls of the latter, where L is the length of the chamber. The length of the major axis of the body oval is (1.6 ... 2.5) d, where d is the diameter of the nozzle. Part of the pipe passing through the chamber is perforated, while the non-perforated part of the pipe from its inner cut is L / 2. Some design flaws of the muffler, which appear during its operation, if necessary, further improve the design to meet the more stringent perspective requirements of vehicles on the limit values of their external noise levels, as well as analysis

design excellence allows us to argue about the potential potential for its further improvement. In particular, in all known variants of the considered silencer design shown in Figs. 1-3, it can be seen that the most energy-intensive first longitudinal lowest intrinsic resonance waveform (and all subsequent odd forms) from the middle (central) silencer chamber can be freely passed into environment through the exhaust pipe 5. The same thing is observed with the second elevation (radial) eigenmode of the chamber volume oscillations. The resonant sound transmission from the camera to the environment also occurs at the fourth longitudinal eigenmode of the chamber volume oscillations (f ₄ = 4c / 2L, where f is the frequency, c is the speed of sound, L is the length of the middle chamber).

The extreme (side) muffler chambers, Fig. 1, according to the graphic description of a muffler known from the general prior art, which are identical end-face end resonators, are tuned to the same resonant frequency range of noise suppression, which leads to unjustified duplication of sound suppression of identical resonant modes, which ultimately limits (narrows) the muffler muffler, and also, in this case, contributes to the unwanted mutual resonant interaction of identical Shackle (end) chambers and prevents the use of each of the cells targeted for noise reduction particular individual (distinguishing) the resonance range in predetermined frequency domain of the audio spectrum.

In modern designs of noise suppressors of automobile ICEs, sound-absorbing gaskets of chamber cavities with fibrous porous materials are widely used to increase the attenuation of sound transmission on these intrinsic resonance modes, such as an expansion cylindrical chamber with internal pipes. An example is the design of silencers for automobile ICEs described in the utility model certificates No. 15494, IPC 7 F 01 N 1/24, 2000, No. 26595, IPC 7 F 01 N 1/00, 2002, No. 27408, IPC F 01 N 1/08, 2003, No. 28733, IPC 7 F 01 N 1/00, 2003. In particular, most automobile manufacturers producing cars use the design of one of the silencers of the exhaust system of an internal combustion engine with filling the chamber cavity (from several chambers) of the muffler with basalt fiber packing. Having sufficiently high heat-resistant and sound-absorbing characteristics, such

the fibrous-porous sound-absorbing packing, in most cases, attenuates unwanted defective resonant high-frequency “whistles” of the muffler, primarily on the “small-sized” fourth longitudinal and second radial eigenmodes of oscillation of the air chamber volume. However, this design has a number of significant drawbacks, the main of which are as follows:

- Porous packing of fibrous basalt fiber 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 service life. It should be noted here that it is internal corrosion, and not mechanical loads, that are the main cause of the destruction of silencers in automobile ICEs;

- The use of fibrous basalt fiber, due to the above reasons, forces, in turn, to use expensive stainless chromium-nickel steels, use additional devices for forced suction of the accumulated condensate from the chamber cavity by various diffuser receivers, which additionally complicates the design and makes it more expensive;

- During the operation of the vehicle, basalt fibers are partially blown away by the flow of exhaust gases from the silencer cavity into the environment, which leads to harmful and harmful to human health air pollution by small particles of basalt fibers;

- 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 (as a rule, at the frequency of the lowest zero eigenmode of the chamber cavity);

- During the long-term operation of the device, the porosity of the fibrous packing of the chamber decreases due to the accumulating effect of carbon particles (soot) and liquid condensate (“coking” of the pores), which entails 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;

- The use of basalt fibers in the production technology of 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.

In connection with the technical, cost, and environmental shortcomings and problems outlined above, the designs of multi-chamber resonator silencers continue to improve, lacking to one extent or another many of the disadvantages inherent in silencers containing fibrous sound-absorbing packings.

As a prototype, the design of the silencer of the exhaust noise of an internal combustion engine is described, described in the USSR author's certificate No. 1618898, IPC 5 F 01 N, publ. 01/07/91, BI No. 1. The silencer comprises a housing with end walls, first and second nozzles installed in the end walls and partially placed inside the housing with the output sections placed respectively from the opposite end walls and on different sides of the median plane perpendicular to the axis of the housing and passing through its geometric center, and transverse perforated partitions, the first pipe crossing the partitions and provided with an internal perforated section, and the second placed coaxially to the housing and provided with a section perforations placed between the partitions and placed in the casing.

The complex geometry of one of the pipes (two bends in length) complicates the design of the muffler. In addition, an analysis of the design of the silencer shows that there are opportunities to further increase the efficiency of sound attenuation, as well as to reduce hydraulic and aerodynamic drags, but to further optimize the design and the relative position of individual elements of sound attenuation.

The technical result of the claimed utility model, which is objectively manifested when using it, is to simplify the design, increase its manufacturability, while increasing the efficiency of reducing exhaust noise.

The specified technical result in the implementation of the utility model, characterized by an independent claim 1 of the formula of the utility model, is achieved by the fact that in the known silencer of exhaust gas exhaust gas of an internal combustion engine comprising a cylindrical body with end walls, in which through transverse perforated partitions

three chambers are formed, the inlet and outlet pipes, one of which is located coaxially with the housing, while the cavity of the pipes are connected to the cavities of the respective chambers by means of their open sections and through perforated sections, one inlet and two exhaust chambers are formed in the silencer cavity, the lengths of which, respectively, correlate as 3/8 ± 0.01: 2/8 ± 0.01: 3/8 ± 0.01 of the full length of the silencer body, the inlet pipe is fixed to the end wall of the exhaust chamber, made rectilinear, located axially to the axis of the silencer body, its open section and the perforated through section are located inside the cavity of the intake chamber receiving exhaust gases, the total passage area of the open section of the inlet pipe is comparable with the total area of the through holes of the pipe perforation section, in addition, the open section of the pipe is located at a distance from the transverse perforated partition, limiting the inlet chamber, equal to half its length, minus 0.2 ... 0.4 of the inner diameter -D- of its cross section, the outlet pipe ra laid coaxially to the housing, mounted on the end wall of the inlet chamber, its through-perforated section and open section, respectively, are placed in the chambers organizing the exhaust gas and having lengths 2/8 and 3/8 of the total length of the muffler, while the through-perforated section of the pipe is located between transverse perforated partitions, on both sides of the middle of the chamber formed between them, symmetrically to the median plane perpendicular to the longitudinal axis of the silencer body, and its open slice is placed inside an adjacent with it the camera, at a distance from the transverse partition equal to half the length of the chamber in which it is located, minus 0.2 ... 0.4 of the inner diameter -D- of its cross section, in addition, the total area of the passage section of the open exhaust outlet the nozzle is commensurate with the total area of the through holes of the nozzle perforation section; the total area of the perforation holes in the partition restricting the inlet chamber is at least twice the total area of the perforation holes in the partition separating the outlets chamber, and the total area of the holes of the perforated portion of the exhaust pipe and perforations in the partition wall, disposed in the outlet chamber is not less than the total area of perforations in the wall bounding the inlet chamber.

In the specifically considered example of the design of the muffler, the prototype of which was the object of acoustic research (the results are given below), the distance -a between the axes of the pipes is 63 mm, while the pipes have an outer diameter of 45 mm, the wall thickness s = 1.5 mm, and through perforated portions of the nozzles are composed of 72 perforation holes with a diameter of d = 5 mm and a pitch of h = 10 mm. The transverse partitions are made in the form of a stamped part from a metal sheet with a thickness of s = 1.5 mm, the distance -b- between the partitions is 125 mm, while 60 perforation holes with a diameter of d = 5 mm and a pitch are made in the partition placed inside the cavity of the outlet chamber h = 12.5 mm, and 125 perforation holes with a diameter of d = 5 mm and a pitch of h = 9 mm are made in the partition of the outlet chamber located inside the cavity. The maximum cross-sectional dimension of the silencer body is 200 mm, the minimum is 130 mm, and the length of the silencer body is 500 mm.

With this design, the silencer design is simplified, and the cost of its manufacture is reduced. At the same time, the efficiency of the silencer not only does not deteriorate, but also increases due to the fact that the new design creates prerequisites for minimizing the resistances and increasing the proportion of dissipation of acoustic energy in the perforation holes of the pipes and partitions. In addition, conditions have been created under which the entire cavity of the silencer body (all three chambers) begins to work efficiently (drown out noise) from lower frequencies, i.e. Perform the function of an effective low-frequency damping device. The optimization of the degree of perforation of the pipes and internal partitions, as well as the lengths (volumes) of the chambers, made it possible to provide low acoustic, hydraulic, and aerodynamic drags, which reduced the power loss of the internal combustion engine.

Comparison of scientific, technical and patent documentation on the priority date in the main and related sections of the MKI shows that the set of essential features of the claimed solution was not previously known, therefore, it meets the patentability condition of “novelty”.

The proposed technical solution is industrially applicable, because can be manufactured industrially, efficiently, feasibly and reproducibly, therefore, meets the patentability condition "industrial applicability". At the same time, industrial production is useful

models are possible on standard equipment using well-known, well-established technologies.

Other features and advantages of the claimed utility model will become apparent from the following detailed description, given solely in the form of a non-limiting example and with reference to the accompanying drawings, illustrating a preferred embodiment, which shows a diagram of the proposed exhaust silencer and its individual components.

Figure 1 shows a specific embodiment of the inventive exhaust silencer. The arrows indicate the trajectory of the exhaust gases inside the silencer body;

Figure 2 shows a cross-section along aa of the silencer body;

Figure 3 shows a prefabricated module of the internal elements of the silencer, including the inlet and outlet pipes installed in the perforated partitions;

Figures 4 and 5 show views of "A" and "B" on perforated partitions;

Figures 6 and 7 show a perforated baffle of the silencer inlet chamber;

On Fig and 9 shows a perforated partition of the exhaust chamber of the muffler.

The letters in the drawings show:

X-X - the median transverse plane of the muffler;

Y-Y - the longitudinal axis of the silencer body;

D is the inner diameter of the inlet or outlet pipes, mm;

a is the distance between the axes of the nozzles, mm;

d is the diameter of the perforation holes in the pipes and partitions, mm;

b is the distance between the partitions, mm;

h is the pitch of the perforation holes, mm;

s is the wall thickness of the nozzles and partitions, mm

Figure 10 ... 12 shows the results of an experimental evaluation of the effectiveness of the inventive silencer. The tests were carried out on a Class B passenger car mounted on a dynamometer stand with running drums in a large semi-anechoic acoustic chamber. In particular:

Figure 10 presents graphs of changes in the total sound levels (noise) of the exhaust in dBA;

Figure 11 presents the noise levels of the exhaust at the main frequency of the working process (the frequency of the exhaust impulses along the exhaust route), equal to Hz (where n is the number of revolutions of the four-stroke four-cylinder internal combustion engine);

On Fig presents 1/3 octave spectrum of exhaust noise levels, recorded 0.25 m from the cut of the tail pipe of the main muffler, at an angle of 60 ° to its axis, at maximum torque r = 3500 rpm, at full load (fully open throttle).

The exhaust silencer shown in Fig. 1 comprises a cylindrical body 1 with end walls 2 and 3, in which three chambers are formed by transverse perforated walls 4 and 5 - inlet 6 and two outlet 7 and 8, inlet 9 and outlet 10 nozzles, one of which is located coaxially to the housing 1, while the cavities of the nozzles 9 and 10 are connected to the chamber cavities by means of their open sections 11 and 12 and through perforated sections 13 and 14. The perforation holes in the partitions 4 and 5 are respectively shown at positions 15 and 16. The perforation holes Baths portions 13 and 14 respectively show the numerals 17 and 18. Branch pipes 9 and 10 in the partitions 4 and 5 are fixed in cylindrical otflantsovkah 19 and 20 covering the outer walls and the pipes placed on each of the partition walls in opposite directions

The silencer shown in FIG. 1 operates in the usual manner. The exhaust gases and the sound waves accompanying them (“noisy” exhaust gases) pass through the inlet pipe 9 into the inlet chamber 6 through the open cut 11 and the perforated section 13. From the chamber 6, the gas and sound flows through the perforation holes 15 in the baffle 4 into the outlet chamber 8 and, at the same time, through the perforation holes 18, an open cut 12 in the pipe 10 and perforation holes 16 in the partition 5, gas and sound are also

get into the exhaust chamber 7. From the chamber 7 through the open cut 12 and from the chamber 8 through the perforation holes 14, significantly weakened sound and gas-pulsating flows are discharged into the environment. Moreover, in the process of continuous multiple reflections of sound waves in the cavities of the silencer chambers, the resulting reflected sound waves interact with direct incident sound waves and, due to antiphase additions (interactions), are partially compensated. In areas of sharp changes in the cross sections of the waveguide and the concomitant effect of friction losses (mainly friction of the gas on the surface of the walls of the through holes of the perforation), in particular when resonant vibrations of gas with large amplitudes of vibrations in the necks of the holes of the perforation, irreversible transformations of sound (vibrational) energy occur into thermal energy (friction), with a corresponding weakening of the transmission of sound energy through the exhaust system sequentially from the intake, intermediate and exhaust expansion cameras in the environment.

Compared with the prototype, the claimed utility model is more technologically advanced to manufacture and has a simpler design, which is expressed by the execution of both nozzles in a straight line and the execution of all perforation holes on the nozzles and partitions are basically the same. At the same time, a higher efficiency of the muffler was achieved due to its more optimal acoustic tuning, by rational placement of its individual noise attenuation elements in the expansion chambers of the housing, confirmed by the performed experimental estimates, shown in Fig.10 ... 12. From the presented graphs it is clearly seen that the noise-attenuating efficiency of the claimed design of the muffler mounted as a part of the standard elements of the serial exhaust system of the internal combustion engine of a passenger car manufactured by AVTOVAZ OJSC, model 2110, in comparison with the established standard main exhaust silencer as a part of other regular elements of the system (neutralizer, additional silencer), is significantly higher. The inventive muffler as part of a standard exhaust system showed a higher efficiency of damping exhaust noise:

- by general levels (Fig. 10) - the effect of additional noise reduction averaged 3 dBA;

- additional (to the standard system) noise reduction at the main frequency of the working process (Fig. 11) is 2 ... 11 dBA;

- in the 1/3 octave spectrum with centers 100 ... 250 Hz, the noise level is additionally (to the standard system) reduced by 2 ... 6 dBA, and in the frequency range 630 ... 10000 Hz - up to 6 dBA (Fig. 12 )

Thanks to the use of a technical device made in accordance with the above description and the formula of the utility model, it becomes possible to quickly learn a new, more efficient and better design of exhaust silencers, acceptable for mass use in cars, with low production costs.

Of course, the utility model is not limited to the specific constructive example of its implementation described above, shown in the accompanying figures. Minor changes of various elements remain possible, or their replacement with technically equivalent ones that do not go beyond the scope of the present utility model. In particular, the perforation holes may not be round, but oval, or in the form of slotted slots, their relative position in grouped belts (without going beyond the limitations of the formula and description) can also be different.

Claims (1)

An exhaust silencer of an exhaust gas of an internal combustion engine, comprising a cylindrical body with end walls, in which three chambers are formed by transverse perforated walls, an inlet and an outlet pipe, one of which is located coaxially to the body, while the cavity of the pipes are connected to the cavities of the respective chambers through their open sections and through perforated sections, characterized in that in the cavity of the muffler formed one inlet and two exhaust chambers, the length of which, with responsibly, they are correlated as 3/8 ± 0.01: 2/8 ± 0.01: 3/8 ± 0.01 of the full length of the silencer body, the inlet pipe is fixed to the end wall of the exhaust chamber, made rectilinear, located axially to the axis of the silencer body , its open section and the through perforated section are located inside the cavity of the intake chamber receiving exhaust gases, while the total area of the through section of the open section of the inlet pipe is comparable to the total area of the through holes of the section of the perforation of the pipe, in addition, the open section of the pipe is located at a distance from the transverse perforated partition that borders the inlet chamber equal to half its length, minus 0.2 ... 0.4 of the inner diameter D of its cross section, the outlet pipe is located coaxially to the housing, mounted on the end wall of the inlet chamber, its through the perforated section and the open section, respectively, are placed in the chambers organizing the exhaust gas and having lengths of 2/8 and 3/8 of the total length of the muffler, while a through perforated section of the pipe is located between the transverse perforations partitioned walls, on both sides of the middle of the chamber formed between them, symmetrically to the median plane perpendicular to the longitudinal axis of the silencer body, and its open slice is placed inside the chamber adjacent to it, at a distance from the transverse partition equal to half the length of the chamber in which it is located, minus 0.2 ... 0.4 of the inner diameter D of its cross section, in addition, the total bore area of the open cut of the outlet pipe is comparable with the total area of the through holes of the perforated section radios of the nozzle, the total area of the perforation holes in the partition restricting the inlet chamber is not less than twice the total area of the perforations in the partition separating the outlet chambers, and the total area of the holes of the perforated portion of the outlet pipe and the perforations in the partition located in the outlet chambers is not less than the total area of the perforation holes in the partition restricting the inlet chamber.