DE19638304A1 - Gas-pipe silencer with baffles in chamber - Google Patents

Abstract

The chamber (1) between the inlet and outlet contains slides or baffles (5) at right angles to the flow direction and reducing its free cross-section. The baffles can have different free cross-sections in a chamber of constant cross-section, or alternatively the chamber can vary in cross-section while that of the baffles remains constant. There can be parallel flow passages in the chamber, containing no deflections. The baffles can be of different radial depths and at different distances apart in the axial direction, forming a steadily widening flow path, which can be curved.

Description

The invention relates to a motor vehicle with a reflection silencer according to the Preamble of claim 1 and the use of a reflection silencer according to claim 17.

Different silencer systems are used in motor vehicles. Depending on The type of sound generation can include absorption silencers or reflection silencers, combinations of these and in some cases also throttle dampers with porous ones flowed through layers are used. The silencer is used for reduction the propagation of sound in ducts, pipes and through openings without the media to prevent transport. In motor vehicles, they are used especially for exhaust To reduce noise and intake noises from internal combustion engines and compressors other. Reflecting silencers are used here to reduce the exhaust noise Use in which cross-sectional jumps and series resonators are the essential Represent damping agents. The resulting higher flow resistance leads to a low performance penalty and must be accepted. It is more difficult in the air intake ducts of the internal combustion engine or in the ventilation area. There here a higher flow resistance usually leads to enormous performance losses, is here especially steamed with absorption materials (insulation mats, mineral fibers).

The object of the present invention is a reflection silencer for motor vehicles the lowest possible flow resistance, if desired proportionally should have broadband sound reduction.

This task is achieved with the muffler described at the outset characterizing features of claim 1. With regard to use, the task solved with the features of claim 17.

Reflection silencers reduce the passage of sound in the duct by means of discards (Reflection) of the sound waves towards the sound source. This can also reduce the sound level increase in front of the silencer so that its effectiveness depends on the installation site  can be. Such dampers are more effective, the more numerous the discards are, where as cross-section jumps, deflections and row and Branch resonators are usually used. Depending on the type of sound generation However, it should be noted that cross-sectional jumps and deflections in Channel systems themselves can lead to undesirable noises, so that a reduction in the flow rate is also generally desired. In the case of the motor vehicle, however, this is due to the limited availability Spaces not realizable, so that sound reduction is a difficult problem here represent.

According to the invention, it has now been found that reflection mufflers with several immediately successive scenes and / or diaphragms in the motor vehicle for sound absorption suitable in pipelines. Immediately here means that the scenes and / or Apertures in terms of sound propagation follow one another, that is to say, for example no sound-reflecting wall, redirection, displacement or cross-sectional jump is arranged. The silencer used in motor vehicles according to the invention is therefore a reflection silencer with an inlet and an outlet for a gas flow and in between a chamber in which the cross-direction of the flow and / or orifices are arranged which reduce the flow cross section of the chamber and over the edges (not terminating with the chamber) of the flow path of the Gases leads. "About" does not mean direct contact with the flow path, it can also run over a cover of the edges, as long as sound propagation from the Flow path to the side surfaces of the scenes / panels is possible. The chamber is in front preferably constructed as a pipeline, the chamber cross-section having a variety of shapes are given. However, the chamber cross section is advantageously round or oval structure. The panels are elements that reduce the cross section on all sides Scenes reduce the cross section only over a partial area of the chamber inner wall. Plate-like structures are particularly suitable as backdrops and screens, for example Sheets, including plastic sheets that reflect sound. When using Blen the aperture hole can be round or in another geometry and in the middle or lie off-center in the chamber.

Preferably three to twenty and in particular four to fifteen orifices and / or Scenes provided, which preferably follow one another directly in the chamber. Of the through the diaphragms or over the scenes leading flow path can be essentially Chen constant cross-section or a variable cross-section, for example have a widening or tapering cross-section, and has preferably a clear width of at least that of the inlet and outlet of the chamber.  

The chamber can also be in the flow direction with the same or with a variable one Chen cross-section.

The backdrops and / or diaphragms can also, in particular with the same Cross section of the flow path and the chamber, with different distances be built to each other. By this and described in the previous paragraph Liche geometric designs (different backdrops / diaphragm heights in the stream different volumes between successive scenes or apertures reached, which creates different resonances. This is it possible to design the silencer (also: pipe damper) broadband, so that in one Range from 0.5 to 8 kHz over a continuous frequency section of at least at least 500 Hz in this a resulting attenuation of at least 15 dB (A) is achieved becomes. This attenuation is preferably at any frequency in the frequency section given. In the preferred embodiments, the frequency section is between 1 and 5 kHz and in particularly preferred embodiments the frequency extends Section above at least 1 kHz and in particular above at least 3 kHz and is available preferably in the frequency range from 2 kHz to 5 kHz. With such broadband dampers is achieved according to the invention that the muffler in particular vehicle-specific Effectively lowers noise emissions, that is, noise emissions from vehicles to vehicle due to, for example, tolerances at different frequencies occur.

In a further preferred embodiment, the flow pattern is through the orifices or over the scenes without redirecting them, that is, the screens or scenes are arranged without mutual overlaps with regard to the flow pattern. This results in a particularly low flow resistance, in particular in relation to one another Silencers achieved with resonance chambers that only have small inlet and outlet openings, usually have pipe sections for the gas flow.

The muffler according to the invention preferably comes into pipes in motor vehicles conditions in which a gas pressure of at least 0.3 bar overpressure, ins there is a special 0.6 bar overpressure. The silencer according to the invention can, however can also be used on the suction side, d. H. even in pipelines where there is a low There is negative pressure. The gas flowing through the silencer flows depending on an operating state of the motor vehicle, for. B. an engine load or fan power. A plurality of pipelines can also advantageously be arranged in parallel, in particular more than one flow path can be provided in one chamber. Especially with the latter Embodiment it becomes possible for two or more flow paths to be common  Have scenes and / or screens between which a gas exchange from one Flow path to the other (and back) is possible. To the flow resistance in to lower the flow path even further, and if necessary to make the twins to reduce spaces between the scenes or diaphragms between the stream path and the (not closing with the chamber) edges of the scenes or A sound-permeable cover can be provided, for example, by can be punctured. The holes are here with the volumes between the scenes or Adjust panels to continue good sound reduction (sound transmission through the holes). The or one of the flow paths preferably runs along the bottom inner wall area of the chamber so that the volumes (Spaces) between the scenes or panels are open at the bottom. Hereby clogging of these gaps with oil or water, for example, is also avoided.

The silencer is preferably provided for the passage of air and in particular the muffler serves as an air inlet duct for an internal combustion engine of the motor vehicle. This form of training comes in particularly advantageous with a loader, in particular Turbocharger used. The muffler according to the invention is used here in particular to dampen charger noise caused by unbalance in the charger rotor will. The disturbing noise that occurs here is not only due to the supercharger speed dependent, but even more from manufacturing tolerances, so that a broadband sound lowering in the pipe between the charger and the internal combustion engine is required is because the interference frequencies that occur are individual, that is, they cannot be specified precisely.

The invention also relates to the use of the silencer described above, ins special pipe damper in a motor vehicle or as an air intake pipe of an internal combustion engine machine, in particular an internal combustion engine operated with a loader.

The muffler according to the invention works with several Helmholtz resonators, which are in Series are connected. By changing the dimensions of the resonators (volume) between the scenes or screens, the diameter of the flow channel or the Aperture opening, length and diameter of inlet pipes and outlet pipes as well even when using covers the diameter of their openings can be adjust these to each other in order to obtain the desired broadband sound reduction.

The invention is described below with reference to drawings and exemplary embodiments described in more detail.

Show it:

Fig. 1 is a narrow-tube shock absorber;

Fig. 2 is a first wide-band-tube shock absorber;

Fig. 3 is a second wide-band-tube shock absorber;

Fig. 4 is an attenuation spectrum of a mittelbreitbandigen tube damper;

FIG. 5 shows a flow tube with two flow paths communicating with each other; and

Fig. 6 is a diagram showing the damping characteristic of the damper tube of Fig. 5.

The tubular damper 1 shown in Fig. 1 is composed of a tubular chamber 2, which is provided at its one end with an inlet nozzle 3 and at its opposite end with an outlet. 4 In the chamber 2 five ring diaphragms 5 are fastened which are connected with their outer edges 6 to the inner wall 7 of the tubular chamber 2 . The openings 8 of the ring diaphragms 5 have approximately the same clear width as the nozzles 3 and 4 and are arranged to cover them. This results in a flow path 9 (arrow) through the tubular damper 1 without deflections on the orifices 5 . In the case of a gas flow through the tube damper 1 , the spaces 10 form between the ring diaphragms 5 and the first or last ring diaphragm and the side walls 11 of the chamber 2 resonance chambers which, according to the geometry of the tube damper 1 , in the tube damper 1 to one Reduce sound in a certain frequency range.

In order to broaden the frequency range in which the sound reduction takes place, the volume of the intermediate spaces 10 can be changed by changing the distance between the ring diaphragms 5 , changing the size of the openings 8 and / or changing the outside diameter of the ring diaphragms 5 . The last two possibilities are illustrated in FIGS. 2 and 3. (Identical numbers of tens stand for similar parts) The pipe damper 101 is basically constructed in the same way as the pipe damper 1, with the difference that the openings 108 only have the clear width of the inlet connector 103 and the outlet connector 104 in the first orifice 105 seen in the direction of flow (arrow) Has. The remaining ring diaphragms 105 a have an increase in the diaphragm diameter 108 seen in the flow direction, so that the interstices 110 have decreasing volumes in the flow direction. On the side wall 111 , which corresponds to the outlet port 104 , there is also a cross-sectional jump, which also serves to dampen vibrations. In contrast to this, the tubular damper 201 from FIG. 3 has diaphragm openings 208 which all have approximately the same internal width as the nozzles 203 and 204 . However, since the chamber 202 is tapered in a funnel shape in the direction of flow (arrow), there are again decreasing volumes of the spaces 210 a as seen in FIG. 2 in the direction of flow. Here too, as in FIG. 2, a wider damping range is achieved with lower absolute values of the damping.

In FIG. 4, a further embodiment of a damper tube 301 is illustrated, which is compared to a smooth-walled pipe four hundred and first The structure of the tubular damper 301 is similar to that shown in FIG. 2 with the difference that only two different diaphragm openings, but these are arranged alternately, as seen from the center towards the inlet and outlet. This results in a reduction in the sound level of an average of 25 dB compared to tube 401, which is comparable in terms of passage and length, between 2000 and 4500 Hz, as a result of which considerable noise reduction is achieved.

The tubular damper 501 shown in Fig. 5 has a significantly different, but basically the same structure compared to the tube dampers described above. Already externally it is striking that the tubular damper 501 is bent banana-shaped and has an oval cross-section. The oval cross section is essentially constant over the course of the tubular damper. Inside, the tube damper 501 includes an upper flow path 519 and a lower flow path 529 . Between these flow paths 519 and 529 , a cross-shaped web 512 is inserted, the four legs 513 to 516 of which are connected to the inner wall 507 of the tubular damper 501 . As a result, the interior of the tubular damper 501 is divided into four axially extending subspaces, of which the upper forms the upper flow path 519 and the lower forms the lower flow path 529 . In the remaining subspaces 517 and 518 , which are opposite one another, partitions 520 are inserted at the beginning of the tubular damper 501 and at the end and at irregular intervals over the course thereof, dividing the subspaces 517 and 518 into individual sections 521 with different adjacent (but the same ones) divide opposite) volumes. Holes 522 are embedded in the legs 513 to 516 in the cross-shaped web 512 , so that the upper flow path 519 communicates with the subspaces 517 and 518 and these in turn communicate with the lower flow path 529 . This ensures that partial gas flows (arrows) flowing through the flow paths 519 and 529 and over the edges 523 of the partition walls 520 have only a low flow resistance, on the other hand the legs 513 to 516 are permeable, so that the partition walls 520 for these sen There are scenes between which there are resonance rooms for sound. This design also has the advantage that non-gaseous components, such as oil droplets, contained in the gas stream, when they separate from the upper flow path 519 , through the holes 522 , the sections 521 and again through the holes 522 into the lower flow path 529 , who then takes these components with them and carries them out. This avoids the soiling of sections 521 .

The damping effect is shown in FIG. 6, the broken line representing the sound pressure level after the pipe damper 501 , the solid line the sound pressure for a correspondingly constructed pipe without the partition walls 520 and without the cross-shaped web 512 . Between about 800 Hz and 6 kHz, a sound reduction of at least 25 dB (A) is achieved over the entire range, individual frequencies are even significantly higher. A clear reduction in the sound level has also been achieved over the entire spectrum in absolute terms (L) and also for human hearing (A) (right part of the diagram).

The invention enables simple and inexpensive sound reduction in gas-carrying Pipes, especially for pipes with air flow.

Claims (20)

1. Motor vehicle with a gas throughflow formed as a reflection muffler pipeline through which gas flows during operation of the motor vehicle depending on the operating state, characterized in that the reflection muffler (* 01 ) has an inlet (* 03 ), an outlet (* 04 ) and In between there is a chamber (* 02 ), in which transverse to the flow direction (arrow), the flow cross-section narrowing backdrops ( 520 ) and / or diaphragms (* 05 ) are arranged, over the edges of a flow path (* 09 , 519 , 529 ) of the gas leads. 2. Motor vehicle according to claim 1, characterized in that at least three coolies sen ( 520 ) and / or panels (* 05 ) are provided. 3. Motor vehicle according to claim 1 or 2, characterized in that the scenes ( 520 ) and / or diaphragms (* 05 ) in the flow path guided over this (* 09 , 519 , 529 ) release the same and / or different flow cross sections. 4. Motor vehicle according to one of the preceding claims, characterized in that the chamber (* 02 ) in the flow direction (arrow) has the same and / or different cross sections. 5. Motor vehicle according to claim 4, characterized in that the cross section of the chamber ( * 02 ) increases or decreases in the direction of flow (arrow). 6. Motor vehicle according to one of the preceding claims, characterized in that the scenes ( 520 ) and / or diaphragms (* 05 ) are matched such that in the range between 500 Hz and 8 kHz over a section of at least 500 Hz a resultant damping of at least 15 dB (A) are reached. 7. Motor vehicle according to one of the preceding claims, characterized in that the scenes ( 520 ) and / or panels (* 05 ) are arranged without overlaps, so that between the inlet (* 03 ) and the outlet (* 04 ) a middle if necessary curved flow course without deflections on the scenes ( 520 ) and or orifices (* 05 ). 8. Motor vehicle according to one of the preceding claims, characterized in that the reflection silencer (* 01 ) is designed for an operating pressure of at least 0.3 bar, in particular at least 0.6 bar. 9. Motor vehicle according to one of the preceding claims, characterized in that that a plurality of gas-flowable pipelines arranged in parallel are provided. 10. Motor vehicle according to one of the preceding claims, characterized in that in the chamber ( 502 ) a plurality of flow paths ( 519 , 529 ) are provided. 11. Motor vehicle according to claim 10, characterized in that at least two of the flow paths ( 519 , 529 ) have common scenes ( 520 ) and / or diaphragms between which the flow paths ( 519 , 529 ) can communicate with one another. 12. Motor vehicle according to one of the preceding claims, characterized in that a sound-permeable cover ( 512 ) is arranged between the edges ( 523 ) of the scenes ( 520 ) or diaphragms and the flow path ( 519 , 529 ) running over these edges ( 523 ) . 13. Motor vehicle according to claim 12, characterized in that the sound-permeable cover ( 512 ) has holes ( 522 ). 14. Motor vehicle according to one of the preceding claims, characterized in that the reflection silencer (* 01 ) is designed to flow with air. 15. Motor vehicle according to claim 14, characterized in that the reflection sound damper (* 01 ) is an air inlet pipe for an internal combustion engine of the motor vehicle, through which combustion air flows to the internal combustion engine during operation of the internal combustion engine. 16. Motor vehicle according to claim 15, characterized in that the reflection sound damper (* 01 ) is arranged between the internal combustion engine and a charger or compressor, in particular a turbocharger. 17. Use of a reflection muffler with an inlet, an outlet and in between is a chamber in which the flow is transverse to the direction of flow cross-sectional backdrops and / or panels arranged in succession are, over the edges of which a flow path of a gas leads, in a motor vehicle. 18. Use according to claim 17, characterized in that the reflection sound air flows through the damper. 19. Use according to claim 17 or 18, characterized in that the reflection muffler is an air inlet pipe of an internal combustion engine of the motor vehicle. 20. Use according to claim 19, characterized in that the air inlet pipe is intended for use between the internal combustion engine and a charger or Compressor, in particular a turbocharger, which is intended for the internal combustion engine to be charged with combustion air.