EP1403506B1 - Silencer for the reduction of air noise and method for the production thereof - Google Patents

Abstract

The attenuator for air noise, in particular, in the suction channel of an internal combustion engine comprises a duct (12) combined with a resonator chamber incorporating cutouts (13), partition walls (14) and a closure lid (14) distanced from the duct wall. An Independent claim is also included for a method for producing the proposed noise attenuator.

Description

State of the art

The invention relates to a silencer for reducing air noise, in particular in the intake tract of an internal combustion engine, according to the preamble of claim 1. Furthermore, the invention relates to a method for producing the above-mentioned silencer.

A silencer of the aforementioned type has been disclosed by DE 199 43 246 A1. This silencer is based on the principle of a so-called Helmholtz resonator. Here, a muffler is proposed, which is provided with an inlet, an outlet and a resonator housing arranged therebetween, wherein the resonator housing has a circular cross-section and in the resonator a charge air tube with a plurality of through-going recesses acting as resonance bores, is used. The resonance bores are distributed over the entire circumference of the circular cross section of the charge air pipe. In one embodiment of the invention, the space between the resonator housing and charge air tube is divided by Segmentierwände into individual resonator chambers. Furthermore, the resonator housing is designed as a casting and resonator housing and charge air tube have a steadily curved shape in the same sense. Here, on the one hand, there is the disadvantage of an increased space requirement, since the charge air pipe is completely enclosed by the resonator housing. On the other hand, the production is complicated, complicated and expensive due to the large number of parts and the materials used. Likewise, the production of complicated curved air ducts is extremely difficult or impossible.

DE 201.13.496 U1 describes a silencer and a method for producing a silencer according to the preamble of claims 1 and 9.

The object of the invention is to provide a silencer based on the principle of the Helmholtz resonator, which is also to be used for complicated curved geometries, requires a small footprint and is simple in construction. Likewise, the object is to develop a method for producing such a silencer.

The stated object is solved by the features of patent claim 1. Furthermore, according to claim 10, the object is achieved with respect to the method.

Advantages of the invention

The silencer according to the invention for reducing air noise, in particular in the intake tract of an internal combustion engine, has an inlet, an outlet and an air line arranged between inlet and outlet, wherein the air duct includes the means for reducing the air noise. Inlet and outlet can have any cross-sectional shape, as well as the connection possibilities at the inlet and outlet can be varied as desired. Cross-sectional shape and connection options are of course dependent on the inlet and outlet attached further air duct parts. Preferably, this air duct should be arranged in the flow direction behind an air filter, ie on the clean air side. Also shape, cross section and length of the air duct are arbitrary and adaptable to the corresponding installation conditions. In the course of the air duct, at least one partial segment at the circumference of the air duct is closed by a resonator housing cover corresponding thereto with a radial distance from the wall of the air duct to form a resonator chamber. The closed by the Resonatorgehäusedeckel sub-segment occupies only a portion of the circumference and never the entire circumference. Via webs, a distance of the resonator housing cover is made to the wall of the air duct to achieve a chamber volume for the Helmholtz resonator. The shape and design of the Resonatorgehäusedeckels depends on the desired volume of the resonator and can be arbitrarily selected depending on the desired resonance range. In the case of the existence of several resonator chambers on a portion of the air line, these are independent of each other and are not in direct connection. Recesses are provided in the wall of the air duct within the resonator chamber in order to connect the interior of the air duct to the resonator chamber.

These recesses are in shape and size dependent on the resonance areas to be covered. Due to the fact that in this solution only partial segments are used by the scope of the air duct as a resonator, there is a great advantage in terms of space compared to the full-scale resonator. Likewise, this solution offers a weight advantage because much less material is used. In the course of the ever advancing demands on space utilization and weight saving in the automotive industry in general, these advantages are to be estimated as significant. Furthermore, there is an immense economic advantage in that the number and complexity of the components used are kept low.

This embodiment also includes a possibility of use in the exhaust system of an internal combustion engine. Due to the small footprint, e.g. in the underbody of a car, and still demanded claims to the noise insulation, it is sometimes difficult to accommodate the required silencer. Likewise, due to further design-related needs, such as the attachment of the driven or non-driven axles, or compliance with aerodynamic specifications, sometimes very complex curved geometries of the exhaust line. Especially here, the silencer according to the invention is advantageous over the known in the art systems.

In an advantageous embodiment of the invention, the entire muffler is made of an injection-moldable material. These may preferably be polyamide or polymeric materials having similar properties. A certain limitation of the choice of material results from the place of use in the engine compartment, where factors such as the temperature or possibly occurring vibrations are the influencing factors. Here, however, there are enough materials in the prior art that meet even the most difficult requirements and can be used to manufacture this silencer. In the course of the end-of-life vehicle regulation, this results in the advantage of easier recycling, since the complete silencer is made of a uniform material and does not first have to be separated into different materials.

A further advantageous embodiment of the invention provides that the resonator chamber is arranged on a bent portion of the air line. Due to the increasingly cramped space in the engine compartment, it is sometimes necessary to bend air lines in a very complex shape to give these air lines a certain curvature. Due to the simple design, it is possible to arrange a resonator to almost any, even very complex curved air duct. Thus, despite very complex laid air ducts, the demands on the noise insulation can be maintained.

In a further advantageous embodiment of the invention, the recesses are formed by perforated plate-like recesses in the wall of the air line. The size of the perforated plate-like recesses, ie the diameter and the distance from each other, have an influence on the frequency range of the resonator. Size and distance will be determined by the frequency to be minimized. Likewise, the depth of the perforated plate-like recesses due to the wall thickness of the air duct at this point has an influence on the frequencies. By varying the wall thickness of the air duct, different frequency ranges can be covered from the outset. Since the perforated plate-like recesses are formed in the wall of the air line, resulting in the interior of the wall no edges and thus an extremely small influence on the air flow.

In a further advantageous embodiment of the invention, a molded part is introduced into the recesses and firmly connected to this recess. In the molded part perforated plate-like recesses are arranged. This means that in the production of the air line, a large recess in the region of the resonator chamber is recessed and subsequently a lochblechartiges molding is introduced into this recess. This molding can, for. B. be made of sheet metal or plastic and can be connected via a whatsoever kind of welding process, a Klipsmechanismus or other, known in the art forms of connection possibilities with the air line. Again, there are extremely low edges in the region of the recess and thus a slight influence on the flow. This solution has the economic advantage that the air line can be basically made with a tool and depending on the desired frequency minimization perforated plates with different strengths, different hole spacings and different hole diameters can be introduced later. This allows the air ducts to be adapted to different internal combustion engines and their different characteristics.

It is advantageous if these perforated plate-like recesses are designed annular. This facilitates the manufacture or the use of prefabricated standard perforated plates. However, it can also be other recesses z. B. oval, elliptical or polygonal, souvenir.

A further embodiment of the invention provides that the inner height of the resonator chamber is variable by a variation of the resonator housing cover. This can be z. B. realize that the web height of the Resonatorgehäusedeckels, which yes determines the radial distance between the housing wall and the housing cover is changed. A changed web height results in a changed chamber volume, which results in a change of the effective frequency range. Likewise, an inner lid in Resonatorgehäusedeckel souvenir, which by a shift in the Resonator chamber causes a changed chamber volume. In this way, an adaptation to various internal combustion engines could be realized.

According to a further embodiment of the invention, a plurality of resonator chambers with differing resonant properties are arranged in the course of the air line. The differing resonance properties are achieved by variations of the hole diameters, the hole thicknesses, the number and the distance of the holes to each other and the available chamber volume. There is no direct connection between the individual resonator chambers and they are to be regarded as independent of each other. This makes it easy to realize a multi-chamber broadband resonator.

The inventive method for producing a muffler for reducing air noise in internal combustion engines is as follows. An air line with an inlet and an outlet is produced by injection molding, wherein in the injection molding at least one sub-segment remains recessed from the circumference of the air line. This can be achieved by a special mold of the injection mold or by a subsequent cutting or removal of this sub-segment from the air line. Preferably, the sub-segment is omitted at curved pipe segments of the air line in the outer region of the curvature. Thereafter, the sub-segment is sealed to the outside sealingly with a resonator housing cover with a radial distance to the wall of the air line. In this case, the resonator housing cover is preferably also an injection-molded part and so, by choosing the web height of the resonator housing cover, compliance with a radial distance from the wall of the air line can be set to produce a chamber volume.

In one embodiment of the method, the recess of the sub-segment is produced by perforated plate-like recesses within this sub-segment directly during the injection molding process. This can be achieved by a special embodiment of the injection mold or subsequently by z. B. drilling or punching can be achieved.

Alternatively, a lochblechartiges molding is firmly connected to the recess of the sub-segment in the wall of the air line. This perforated sheet-like molded part may be a perforated metal sheet or of an injection-moldable or extrudable material, which is either glued or welded directly to the wall of the air duct or is pressed firmly on the resonator housing cover to the wall of the air line. In both alternative methods, a substantially smooth transition results, especially in the region of the joining edges between the molded part and the air duct or in the region of the perforated plate-like recess. In the case of the perforated plate-like molded part, this can already be pre-cut or pre-produced in the form of the recess of the partial segment and thereby lead to a rapid and economical production of the silencer.

In a further embodiment of the method, the resonator housing cover is connected to the wall of the air duct surrounding the subsegment via a friction welding process. However, this connection could also be realized via bonding or other connection methods known in the prior art.

These and other features of preferred embodiments of the invention will become apparent from the claims and from the description and the drawings, wherein the individual features are realized individually or in each case in the form of sub-combinations in the embodiment of the invention and in other fields and can represent advantageous and protectable versions for which protection is claimed here.

drawing

Figur 1

Darstellung des erfindungsgemäßen Schalldämpfers mit dazugehörigem Lochblech

Figur 2

Darstellung des erfindungsgemäßen Schalldämpfers mit integrierten Aussparungen

Further details of the invention are described in the drawing with reference to schematic embodiments. This shows

FIG. 1

Representation of the silencer according to the invention with associated perforated plate

FIG. 2

Representation of the silencer according to the invention with integrated recesses

Description of the embodiments

FIG. 1 shows an embodiment of the silencer according to the invention. Shown is an air line 12 with means for sound reduction, disposed between an inlet 10 and an outlet 11. Preferably, the air line 12 has a substantially circular cross-sectional shape. The air duct 12 has in this embodiment, a significant curvature, but can also be bent over a complicated curved or straight, without any curvature fraction. Inlet 10 and outlet 11 have mounting surfaces on to install this line piece between two secondary lines or an air filter and a secondary line. These mounting pads can be made arbitrarily. They are executed according to the corresponding pads. Preferably, the air line with inlet and outlet made of an injection-moldable material, in particular glass fiber reinforced polyamide executed. Injection moldable materials result in a high degree of design variety but are not absolutely necessary. A metallic or partially metallic design is conceivable and would lead to the same positive results in the noise reduction. In the outer curved portion of the air duct 12, three recesses 13 are provided, which occupy only a portion of the circumference of the air line 12. The recesses 13 can be excluded or omitted directly in the manufacture of the air line, in particular during injection molding by appropriate choice of tools, but it is also possible to make these recesses later by means of a cutting or burning tool. The recesses 13 are separated from one another by webs 14. The webs 14 cause a separation of the recesses 13 and thus achieve independence of the individual thus forming chambers. A corresponding to the size of the recesses 13 resonator housing cover 15 closes the recesses 13 sealingly. The resonator housing cover 15 may have any shape adapted to the installation conditions. The height of the forming chambers between the resonator housing cover 15 and air duct 12 and the recesses 13 is formed by the webs 14. In FIG. 1 it can be seen that three resonator chambers result here, which are independent of one another and are closed together by the resonator housing cover 15. Preferably, the resonator housing cover 15 is made of an injection moldable material, but it is also possible to use metal or a metal-plastic combination here. The connection between the resonator housing cover 15 and the air duct 12 preferably takes place via a friction welding method, but all other welding or connecting methods which are known in the prior art are also possible. To achieve the Helmholtz effect perforated plate-like moldings 17 are provided with recesses 16. The shape of the mold parts 17 is adapted to the recesses 13. Preferably, these perforated plate-like moldings 17 are made of metal, but they may also consist of plastic, such as polyamide or other materials known in the art. The recesses 16 may be round, oval or angular, but they are preferably, as seen in Figure 1, round, due to the fact that prefabricated perforated plates are already ready to relate. The wall thickness of the perforated plates is freely selectable, the wall thickness has an influence on the neck length and thus has on the resonator properties of the respective resonator chamber. The molded part 17 is introduced into the recesses 13 in such a way that as little as possible, otherwise only a very small edge results in the flow of the fluid flowing through. The fixation of the moldings 17 is then carried out either via an adhesive or welding process, it is also conceivable that these moldings 17 are pressed firmly by corresponding corresponding parts in the resonator housing cover 15, in the recesses 13. The muffler set forth in FIG. 1 has three resonator chambers and can therefore filter out a broadband spectrum of resonance frequencies. By choosing a different wall thickness of the molded part 17 or different arrangement or design of the recesses 16 and a different from the web height of the webs 14 and the resonator housing cover 15 resulting Resonatorgehäusevolumens can be specifically adjusted to be insulated resonance frequencies. The silencer shown here consists of only five different parts, which can be assembled in a simple manner. This offers a high economic and time advantage over the solutions of the prior art. Furthermore, it is possible with this solution to provide complex and complicated curved Luftleitungswandungen with a broadband multi-chamber resonator. This embodiment is extremely space-saving compared to a full-scale resonator housing known in the prior art and offers great advantages, especially in the increasingly limited area of the engine compartment.

The features required for the understanding of the invention of Figure 2 are as far as they correspond to parts of Figure 1 by the same reference numerals. FIG. 2 also shows an air line 12 with an inlet 10 and an outlet 11. The air line 12 is bent and has recesses 13 on part of its circumference. The connection configurations of inlet 10 and outlet 11 as well as the geometry of the air line itself can be taken from the description of FIG. The recesses 13 of the air line 12 are separated by webs 14 from each other. This separation causes a complete independence of the individual chambers from each other. The recesses 13 have different recesses 16. The recesses differ by their size and their cross-section in the respective recesses 13. Preferably, the air duct 12 is made of an injection-moldable material and the recesses 16 are formed directly during injection molding by the tool. Alternatively, however, these recesses 16 can also be retrofitted with the aid of suitable tools. In both cases, the recesses 16 may have circular, angular or otherwise any known shape. A variation of the cross-sectional area of the recesses 16 and the wall thickness of the air duct 12, as well as a variation of the resonator chamber volume, results in a change in the effective frequency range, which is reduced. The wall thickness of the air line 12 in the region of the recesses 13 can be influenced by the injection molding process and the existing tool geometry. However, the design of the silencer made of non-injection moldable material and metal would offer no disadvantages in terms of noise reduction. The volume of the individual resonator chambers can be influenced, as in FIG. 1, via the web height and the configuration of the resonator housing cover.

The muffler described in Figure 2 can be made in a simple way of only one material. In the preferred case, no material mix takes place, so that this muffler is sorted and thus has a great advantage in recycling this part. Equally advantageous is the low cost of assembly and the very high flexibility with respect to the installation situation. Furthermore, the muffler described in Figure 2 for different motors with different frequency ranges to be eliminated can be prefabricated and easily adapted by suitable introduction of the recesses 16 of the respective situation. Here the so-called module idea is taken into account, d. H. that a module can be used in different engine variants.

Claims (10)

1. Silencer for the reduction of air noise, having an inlet (10) and an outlet (11), an air duct (12) arranged between inlet (10) and outlet (11), whereby the air duct (12) contains means for the reduction of air noise, whereby - in the course of the air duct (12) - at least one partial segment of the circumference of said air duct (12) is closed by a corresponding resonator housing cover (15), having a radial distance to the wall of the air duct (12) to a resonator chamber, whereby the partial segments are independent from each other and the resonator chamber is connected with the interior of the air duct (12) by recesses (13) provided in the wall of the air duct (12), characterized in that at least one shaped part (17) is inserted into the recess (13) and firmly connected therewith, whereby perforated plate-like recesses (16) are arranged in the shaped part.
2. Silencer according to claim 1, characterized in that the silencer is made from an injection-mouldable material.
3. Silencer according to one of the claims 1 to 2, characterized in that the resonator chamber is arranged at a curved section of the air duct (12).
4. Silencer according to one of the preceding claims, characterized in that the recess (13) is formed by perforated plate-like recesses (16) in the wall of the air duct (12).
5. Silencer according to claim 4, characterized in that the recesses (16) are of circular shape.
6. Silencer according to one of the preceding claims, characterized in that the internal height of the resonator chamber can be modified by a variation of the resonator housing cover (15).
7. Silencer according to one of the preceding claims, characterized in that several resonator chambers with resonance characteristics varying from each other are arranged in the course of the air duct (12).
8. Air-intake system of an internal combustion engine having a silencer for the reduction from air noise according to claim 1.
9. Method for the production of a thermoplastic silencer for the reduction of air noise with internal combustion engines, whereby an air duct (12), having an inlet (10) and an outlet (11) is manufactured by injection-moulding, whereby - in the injection-moulding process - at least one partial segment is recessed by of the circumference of the air duct (12) and said partial segment is independent from other partial segments and whereby the partial segment is firmly closed and sealed towards the outside by a resonator housing cover (15) at a radial distance to the wall of the air duct (12), characterized in that a perforated plate-like shaped part (17) is firmly connected with the recess (13) and that it offers a substantially smooth transition inside the air duct (12), particularly within the area of the joining edges between shaped part (17) and air duct (12).
10. Method according to claim 9, characterized in that the resonator housing cover (15) is connected with the wall of the air duct (12) which surrounds the partial segment by way of friction-welding.

Images