US20070295554A1

US20070295554A1 - Sound Proofing Device and Device for Conducting a Fluid

Info

Publication number: US20070295554A1
Application number: US11/629,840
Authority: US
Inventors: Matthias Flucht; Christoph Heiland; Uwe Gross; Peter Altenhofen
Original assignee: Geiger Technik GmbH
Current assignee: GEIGER TECHNOLOGIES GmbH
Priority date: 2004-06-16
Filing date: 2005-06-14
Publication date: 2007-12-27
Also published as: WO2006018336A1; DE102004029221A1

Abstract

A device for muffling the sound produced by a fluid in a duct, especially the sound produced in an intake pipe of a combustion engine, comprises a wall, whose inside defines a flow passage for the fluid. The device is at least partly tubular, i.e. it has two openings. At the outside of the wall (3) is arranged a plurality of chambers (4), each of which is connected to the flow passage via an aperture (7). The chambers (4) are bounded by the outside of the wall (3) as well as by bars (5, 6, 8) formed at the outside of the wall (3). The chambers (4) function in use as Helmholtz resonators. In addition, a device for the conduction of a fluid with the sound proofing device (1) described is presented.

Description

The invention refers to a device for muffling the sound produced by a fluid in a duct, especially the sound produced in an intake pipe of a combustion engine. Furthermore, the invention concerns a device for the conduction of a fluid, especially for the feeding of air to a combustion engine, comprising a duct.
Various concepts are known for the damping or suppression of unwanted noises resulting from the flow of fluids, especially air or exhaust gases, through piping. On the one hand, it is possible to form holes in those places in piping at which the standing waves forming in the pipe have amplitude maxima, such that diversion of the vibrational energy outwards is possible in order that the desired damping may be obtained. In this regard, it is made use of the fact that the engine compartment is usually acoustically well shielded, such that the diverted vibrations in the engine compartment continue to be damped and cannot penetrate outwards.
Alternatively, it is conceivable to absorb at least part of the sound directly in the pipe.
Various acoustic modules for the engine compartment have been developed for this which are supposed to take account of the thermal, mechanical and acoustic characteristics. With the known solutions, however, it has emerged that provisioning and installation of the modules incur high manufacturing effort, high material costs and a considerable effort on installation or conversion, especially when existing systems are retrofitted.
The object of the invention is therefore to provide a sound proofing device which permits optimized noise suppression and is simple to manufacture. Additionally, especially the possibility of integration into already existing systems is desirable.
This task is solved by a sound proofing device in accordance with claim 1 and a device for the conduction of a fluid in accordance with claim 20.
The device for muffling the sound produced by a fluid in a duct, especially the sound produced in an intake pipe of a combustion engine, comprises a wall, whose inside defines a flow passage for the fluid. Especially, the sound proofing device has, on the outside of the wall, a plurality of chambers with which the flow passage is connected.
The device mentioned is arranged especially in a duct. The device may also be suitable for retrofitting noise control to an already existing duct. Possible ducts would be, for example, a charge air pipe of a turbocharger, e.g. the intake pipe between the air filter and a turbocharger, the intake pipe of a combustion engine, an exhaust gas pipe and the like.
However, all other possible pipes, for example an exhaust gas pipe for when a turbocharger is used, can be retrofitted with the device in accordance with the invention. The sound proofing device can be used for noise attenuation anywhere in an air conduction system. Thus, optimum use of the scarce space in the engine area as well as optimum noise suppression can be achieved through the compact design of the device.
Preferably each of the chambers is connected with the flow passage via at least one aperture. Usually, one aperture is provided in each case between each chamber and the flow passage.
The dimensioning of the chambers is such that the dimensions are small in relation to the standing wave to be suppressed or damped.
The cross-section of the apertures is likewise usually small in relation to the wavelength of the acoustic wave to be damped.
The chambers are bounded preferably from the outside of the wall as well as by bars formed at the outside of the wall.
The bars are especially aligned essentially perpendicularly or parallel to the main flow direction of the fluid. At the boundary regions of the device, bars may also be provided, which form a part of enclosing flanges and edge beads, with this type of bar capable of running in any direction.
The chambers are provided in order to work as Helmholtz resonators. Usually, a Helmholtz resonator is a perforated plate, which is spaced at a distance from a wall, in this case from the enclosing wall of the duct. This distance of the perforated plate from the wall corresponds in the present design to the distance between the enclosing wall of the duct and the wall (of the sound proofing device) enclosing the flow passage, said enclosing muffling wall essentially taking on the function of the perforated plate. This distance in turn essentially corresponds to the height of the bars. The Helmholtz resonator works like a selective spring-mass system, which is excited into vibration by the impinging acoustic waves. Depending on the volume, that is especially on the length, width and height of the chambers, as well as on the dimensioning of the apertures, narrow-band damping of the acoustic waves occurs, since internal losses occur due to the excitation of vibrations of the Helmholtz resonators. In the case of resonance, the effect of the Helmholtz resonators is greatest.
In a special embodiment, chambers with different volumes and/or apertures with different aperture cross-sections are provided. Thus, broadband damping can also be performed across a wide spectrum. Tuning is thus possible in the frequency band or frequency range where damping is to occur, especially whether damping is to occur in one or more narrow spectra, in several frequency bands or across a large contiguous frequency range is to be absorbed. This selection can be made by the determination of the dimension(s) of the chambers.
Especially, the chambers and/or the apertures can be dimensioned such that certain frequency ranges of the sound are selectively absorbed. Through provision of chambers and/or apertures of varying size, narrow-band frequency ranges are selectively damped. As a result, a desired noise characteristic can be produced. Additionally, more frequently occurring resonant vibrations can be filtered out, i.e. the damping characteristic can be matched to the excitation spectrum of the engine.
The device is preferably formed in one piece. As a result, production and installation are relatively simple and economical.
Especially, the device is made from thermoplastic polymer. In this regard, polyphenylene sulphide (PPS), polyamide composite material, polypropylene composite material, polyurethane and similar materials, for example, may be used. The materials may comprise a glass fiber fraction in order that heat stability and stability to protracted heat exposure may be increased. Alternatively, the device may consist also of an elastomer, especially a thermoplastic elastomer, rubber or india rubber. By way of simple manufacturing process, an injection moulding method, for example, would be suitable.
The wall of the sound proofing device preferably has an essentially tubular cross-section. Thus, the device is adapted for introduction or pushing into a pipe, for example into the air feed pipe. It thereby forms a kind of lining along a certain section of the pipe.
The chambers may also be closed to the outside, however. This means that the chambers are not closed only during insertion into the pipe, but that an insert with chambers already closed to the outside is provided.
Alternatively, at least one part of the chambers has a side open to the outside. Only during insertion into a pipe are the chambers closed to the outside by the pipe wall. To this end, the outside edges of the bars are pressed against the wall of the pipe and thus more or less close off the chambers. The chambers are then connected to the environment only via the aperture to the flow passage.
The sound proofing device is especially adapted so as to be inserted into a duct such that an area of the inside of the enclosing wall of the duct covers the open sides of the chambers. In the installed state, the chambers thus form closed cavities, which act as Helmholtz resonators. As already stated, the outside edges of the bars are pressed against the enclosing wall of the duct. Perfect contact between all bars and the inside of the enclosing wall of the duct is not absolutely essential to the success of the invention.
The device has a flat shape in one preferred embodiment and, when the module is not installed, the wall is essentially arranged in one plane. In this way, production can be simplified still further. In addition, such a module can be stored in a space-saving manner.
The device just described may have at least one connecting section, which is formed such that at least two adjacent areas of the device can be adjusted at an angle to each other. During installation, the flat device must be capable of being rested against the inside of the duct. This can be effected specifically by bending points or hinges. Enough connecting sections must be provided such that satisfactory adjustment of the device to the shape of the inner wall of the duct is possible. Both plastic and elastic deformation of the connecting sections are possible. Insertion in the case of an insert made as a flat part proceeds by bending the connecting sections to form a jacket section, which roughly corresponds to the inside of the pipe section into which the part is to be introduced. Afterwards, the insert is pushed into the pipe.
Alternatively the device may be formed as an essentially flexible module, such as a mat. For example, if the device consists of an elastomer, then the flat module can be inserted easily into differently shaped ducts. If it is flexible enough, then curved pipe sections will not prevent introduction of the insert, which takes place as described in the last section. The range of applications of the device as an insert is thereby increased. Especially, the module may be used like the lining of a section of the duct fitted with an absorber.
The device is thus especially intended to be suitable for insertion into a pipe, especially also into a curved pipe, from the outside, whereby at least one part of the outside of the device introduced under application of certain pressure into the pipe rests against the inner wall of the pipe. This pressure may be relatively small. It only needs to ensure relatively secure retention of the device in a pipe, i.e. the outer shape of the device and the inside of the pipe section that is intended for the insertion of the device must be matched to one another.
Furthermore, the device may comprise a connecting unit for connecting the device to an appropriate connection point in the engine area. For example, the connecting unit can extend as one piece to that section of the device intended for muffling. During insertion, the device is then introduced into a pipe until the connecting unit protrudes from the opening of the pipe and so facilitates connection to a further connection point, for example to the exit of an air filter, the inlet to the turbocharger or a connecting pipe. The connecting unit can in this way replace a rubber sleeve, which would otherwise have to be attached additionally to the opening section of the pipe. Additionally, it can fulfill sealing functions at connecting sections or serve the purpose of uncoupling two modules, which otherwise would similarly require the use of separate parts. This solution arising from the use of a mono module in accordance with the invention is economical and assembly of individual components is simple to accomplish.
The task posed is also resolved by a device for the conduction of a fluid, especially for the supply of air to a combustion engine, which device comprises a duct and a sound proofing device, as described above. The sound proofing device described above thereby serves especially as an insert for the duct. The device for the conduction of the fluid may be produced especially by retrofitting an already existing duct with the sound proofing device.
Especially, the duct may be adapted to accommodate the sound proofing device in a section of the duct.
The inside of the duct in the area of the section preferably has a bulge for admitting the sound proofing device. To this end, for example, a niche may be formed in the duct, into which the sound proofing device can be inserted. The niche and the design of the external shape of the sound proofing device may be specifically matched to each other.
Especially, the flow cross-section for the fluid in the transition area from the duct to the flow passage of the sound proofing device bounded by the wall does not change, or not substantially, at any rate continuously and not suddenly. A sudden change in the flow cross-section would have the disadvantage that the flow resistance for the fluid increases and thus unwanted energy losses as well as turbulences would arise. Through mutual adjustment of the duct and the sound proofing device, it is possible, despite the fitting or retrofitting of a sound proofing device, to achieve across the entire flow section a more aerodynamic through-flow cross-section which follows the optimum contour.
Further characteristics and advantages of the object of the invention are apparent from the following description of special embodiments. These show in
FIG. 1 a perspective view of a device in accordance with the invention for muffling;
FIG. 2 an enlarged representation of a cross-sectional view of the sound proofing device;
FIG. 3 the device in accordance with the invention of FIG. 1 in another perspective;
FIG. 4 an intake pipe with integrated sound proofing device, partly cut open; and
FIG. 5 the opening area of the intake pipe with integrated sound proofing device.
FIG. 1 shows the device in accordance with the invention for muffling, designated in the following as sound proofing device 1. The sound proofing device 1 in the embodiment is a single-piece insert formed separately from an intake pipe. This has the advantage that the sound proofing device 1 and the intake pipe of a combustion engine or a turbocharger, into which the insert is to be inserted, can be manufactured independently of each other. Especially, one can easily retrofit an already existing air duct with an appropriately adapted sound proofing device 1. Additionally, simple handling of the module during installation as well as economical production are possible.
The sound proofing device 1 is preferably made from plastic. It has been shown that plastic parts can be produced not only simply and more economically, but that materials also are meanwhile available which meet the specified mechanical, thermal and acoustic requirements excellently. For example, the module may consist of thermoplastics with suitable characteristics regarding wear, heat resistance and processability. Possible materials may be polyphenylene sulphide (PPS), polyamide or polypropylene composite materials, to which a glass fiber fraction may be added where necessary. An alternative material for the production of the mono module may be an elastomer.
The outer shape of the sound proofing device 1 is essentially determined by the formation of the section of a pipe/pipe into which the sound proofing device 1 is to be inserted. Especially, the outer shape of the sound proofing device 1 can be adapted to already existing pipes, such that the pipes can be retrofitted with the sound proofing device 1.
The front side of the sound proofing device 1 in the present embodiment has an essentially circular aperture 2 with a diameter d, which is bounded by the flange 8. The diameter d may correspond thereby to the diameter of an outlet opening of an air filter or the diameter of a pre-positioned or connecting duct section in order that losses due to flow resistance may be avoided if possible. Altogether, the influence of the sound proofing device 1 on the flow and thus the pressure loss along the flow path are to be minimized.
The flow passage for the air or the exhaust gases connected to opening 2 is bounded by a wall 3. When a fluid, for example air or exhaust gas, is flowing through the sound proofing device 1, the inside of the wall 3 of the sound proofing device 1 can act as resonator, whereby standing acoustic waves may form. In order that sound suppression and/or muffling may be achieved, the sound proofing device 1 has a plurality of chambers 4, which are bounded by the outside of the wall 3 as well as by radial bars 5 and by bars 6 perpendicular to it and running in a longitudinal direction. As is clear from FIG. 1, the bars 5, 6 form a kind of lattice structure on the outside surface of the wall 3. The chambers 4 are open to the outside in insert 1, but during insertion into the intake pipe are closed by its enclosing wall from the outside, such that defined cavities are created. The chambers 4 can act then as Helmholtz resonators to attenuate the noise. Alternatively, however, chambers 4 already closed to the outside could be formed in the sound proofing device 1.
Each of the chambers 4 is connected with the interior of the sound proofing device via an aperture 7. This is clear from FIG. 2.
With the aid of FIG. 2, which shows an enlarged cross-sectional view of the sound proofing device 1, the mechanism of the sound proofing device will be explained.
Each of the chambers 4 forms a cavity, which is bounded by the outside surface of the wall 3 as base surface and by the bars 5, 6. The volume of the cavities is determined by the spacing of the bars 5, 6 as well as their height. The cavities are connected with aperture 7 to the interior, i.e. to the flow passage, of the sound proofing device 1. The cavities then act as Helmholtz resonators when the sound proofing device has been inserted. Air does not usually flow through the chambers 4 themselves. Even during manufacture, the chambers 4 can be alternatively made as outwardly closed cavities of the sound proofing device 1.
The absorption frequency of a Helmholtz resonator essentially depends on the size of the chambers 4 as well as on the dimensioning of the apertures 7. In this way, certain frequency bands can be selectively damped. This offers the possibility of selecting and tuning the noise characteristic of the frequency spectrum not absorbed by the sound proofing device. On the other hand, via the arrangement of different cross-sections of the apertures 7 and/or by the use of different-sized chambers 4, damping can be performed across a broad band in order that muffling may be as complete as possible. The wall 3 of sound proofing device 1 with apertures 7 essentially forms a circularly curved perforated plate, which is arranged at a certain distance from the inner wall of the duct in which sound proofing device 1 is to be arranged. The distance is thereby determined substantially by the height of the bars 5, 6. In the operating state, each of the Helmholtz resonators acts in a narrow band through excitation of vibrations, which generate internal losses. The damping effect of the Helmholtz resonators is greatest in the case of resonance. The parameters determining resonance volume, namely height, width and depth of the resonance chambers 4, are smaller in this regard than the wavelengths of the acoustic waves to be absorbed.
FIG. 3 shows the sound proofing device in accordance with the invention 1 from another perspective. The second opening 12 of the flow passage of the sound proofing device 1, which in the illustration in FIG. 1 points into the plane of the page, is bounded by a second flange 11.
In the present case, the sound proofing device is formed and/or its openings are arranged such that the sound proofing device can be inserted in the area of a duct bend. The gases entering the first opening 2 flow through the flow passage bounded by the wall 3 and exit the sound proofing device 1 again through the second opening 12 in one or more directions R2, other than the inflow direction R1. The invention is not to be restricted, however, to this embodiment, but, for example, also definitely comprises sound proofing devices with constant flow direction of the fluid.
FIG. 4 shows a cross-sectional view of an intake pipe 9, which has a section 10, in which, as shown in FIG. 1, a sound proofing device 1 is arranged. The bulge in section 10 is caused by the provision of an additional cavity extending beyond the average flow cross-section of the intake pipe 9, into which cavity the sound proofing device 1 is inserted. The section 10 of the intake pipe 9 and the sound proofing device 1 are matched in terms of shape to each other such that the sound proofing device 1 can be inserted precisely into the cavity provided in addition to the flow volume. The diameter d (see FIG. 1) of the flow passage of the sound proofing device 1 is just as large in this regard as the inside diameter of the pipe section which connects in area 10′ to section 10. The same applies to the other opening of the sound proofing device in area 10″. As a result, an increase in flow resistance is prevented relative to an intake pipe not equipped with a sound proofing device. The flow passage of the sound proofing device 1 can therefore aerodynamically follow the contours of the flow cross-section of the intake pipe in the transition areas 10′, 10″, whereby, in the case of retrofitting as well, an aerodynamic, space-saving as well as simple and economically manufacturable solution is provided.
The sound proofing device 1 is safely held in its service position by contact of the flange 8 with a catch of the intake pipe 9 as well as by contact with a second catch in the area of the rear aperture.
Especially, the intake pipe 9 is an air-intake pipe between air filter and turbocharger. The invention is not restricted, however, to this application. Rather, the sound proofing device in accordance with the invention can be used in all possible pipes through which a fluid, for example air or exhaust gas, flows. For example, the exhaust gas pipe of a combustion engine can also be fitted with the sound proofing device in accordance with the invention 1.
The intake pipe 9 can be manufactured from a suitable plastic. In principle, a one-piece design of the sound proofing device 1 with the intake pipe 9 is also conceivable.
FIG. 5 shows the opening area of the intake pipe 9 with inserted sound proofing device. The apertures 7 of the sound proofing device 1 connect the flow passage of the sound proofing device 1 with the chambers 4 behind it, which work as Helmholtz resonators. In the present example, the sound proofing device 1 is arranged in the region of a bend in the pipe. The sound proofing device 1 can, however, in the context of the invention, extend into any area of the intake pipe 9 and across any section 10.

Claims

1-23. (canceled)

24. A device for muffling sound produced by a fluid in a duct, the device comprising:

a wall having an inside surface that defines a flow passage for the fluid; and

a plurality of chambers formed on at least one exterior surface of the device;

wherein the plurality of chambers are fluidly connected with the flow passage.

25. The device as claimed in claim 24, wherein the at least one exterior surface comprises a plurality of apertures; and wherein each chamber of the plurality of chambers is fluidly connected with the flow passage by at least one aperture of the plurality of apertures.

26. The device as claimed in claim 25, wherein at least some chambers of the plurality of chambers have different volumes relative to one another; and

wherein at least some apertures of the plurality of apertures have different relative cross-sectional areas relative to one another.

27. The device as claimed in claim 25, wherein the plurality of chambers and the plurality of apertures are dimensioned so as to dampen a predetermined frequency range of sound.

28. The device as claimed in claim 24, wherein each chamber of the plurality of chambers is bounded by an exterior surface of the wall and by a plurality of defining bars, the bars being formed extending from the exterior surface of the wall.

29. The device as claimed in claim 28, wherein at least some of the plurality of defining bars are aligned substantially perpendicular to a primary flow direction of the fluid.

30. The device as claimed in claim 28, wherein at least some of the plurality of defining bars are aligned substantially parallel to a primary flow direction of the fluid.

31. The device as claimed in claim 28, wherein the plurality of chambers are closed on a side opposite the exterior surface of the wall.

32. The device as claimed in claim 28, wherein at least some chambers of the plurality of chambers have an open side opposite the exterior surface of the wall.

33. The device as claimed in claim 32, wherein the device is constructed and arranged such that when inserted into the duct, an area of an inside of an enclosing wall forming the duct covers the open side of the chambers.

34. The device as claimed in claim 24, wherein the plurality of chambers form a plurality of Helmholtz resonators.

35. The device as claimed in claim 24, wherein the device is formed as one piece.

36. The device as claimed in claim 24, wherein the device comprises a thermoplastic polymer.

37. The device as claimed in claim 36, wherein the thermoplastic polymer is selected from the group consisting of: polyphenylene sulphide, a polyamine composite material, a polypropylene composite material, and polyeurethane.

38. The device as claimed in claim 36, wherein the thermoplastic polymer comprises a glass fiber fraction.

39. The device as claimed in claim 24, wherein the device comprises an elastomer.

40. The device as claimed in claim 39, wherein the elastomer comprises a thermoplastic elastomer.

41. The device as claimed in claim 24, wherein the wall has a tubular cross-section.

42. The device as claimed in claim 24, wherein the device is substantially flat; and wherein the wall is arranged in a plane.

43. The device as claimed in claim 42, further comprising at least one connecting section, the at least one connecting section being constructed and arranged such that two adjacent areas of the device are adjusted to one another at an angle by the at least one connecting section.

44. The device as claimed in claim 42, wherein the device is a flexible module.

45. The device as claimed in claim 24, wherein the device is constructed and arranged to be inserted into a pipe from an outside of the pipe; and wherein, once the device is inserted into the pipe, at least a portion of an exterior of the device rests against an inner wall of the pipe.

46. The device as claimed in claim 45, wherein the pipe is a curved pipe.

47. The device as claimed in claim 45, wherein the pipe is coupled to an engine; and wherein the device comprises a connecting unit that connects the device to a connection point in the engine.

48. A device for conducting fluid, the device comprising:

a duct; and

a sound-proofing device disposed within the duct, the soundproofing device comprising a wall having an interior surface that defines a flow passage for the fluid, and a plurality of chambers formed on at least one exterior surface of the wall, the plurality of chambers being fluidly connected with the flow passage.

49. The device for conducting fluid as claimed in claim 48, wherein the device is constructed and arranged to supply air to a combustion engine.

50. The device for conducting fluid as claimed in claim 48, wherein the duct comprises a bulge to accommodate the soundproofing device; and wherein the soundproofing device is disposed within the bulge.

51. The device for conducting fluid as claimed in claim 48, wherein a flow cross-section of transition area from the duct to the flow passage of the soundproofing device is constant.

52. The device for conducting fluid as claimed in claim 48, wherein a flow cross-section of transition area from the duct to the flow passage of the soundproofing device changes at a continuous and constant rate.