Muffler comprising at least one fiber mesh winding unit having at least two mesh density regions, and method for producing fiber mesh winding unit

Abstract

The invention relates to a muffler (100) for a compressed air system, in particular for a brake system of a utility vehicle, comprising at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) having at least two mesh density regions (130, 132, 230, 232, 330, 332, 430, 432, 530, 532, 534, 630, 632, 634), at least one inlet, at least one outlet (120) and a housing, at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) is housed within the housing of the muffler (100) to attenuate noise emissions of air flowing from the at least one inlet to the at least one outlet (120). The invention also relates to a method (700, 800) for producing a fiber mesh roll unit (124, 224, 324, 424, 524, 624) for a muffler (100) for a compressed air system, in particular for a brake system of a utility vehicle.

Description

Technical Field

[0001] The invention relates to a silencer for a compressed air system, in particular for a brake system of a utility vehicle, comprising at least one fiber mesh roll unit having at least two mesh density regions.

[0002] Furthermore, the invention relates to a method for producing a fiber mesh roll unit for a silencer for a compressed air system, in particular for a brake system of a utility vehicle. Background Art

[0003] In practice, it is known that compressed air systems for brake systems of utility vehicles usually release a large amount of compressed air into the environment in a very short time. This expansion process generates considerable noise. In order to keep the noise emission at an acceptable level, a silencer or muffler is usually necessary for the compressed air system.

[0004] Inside the muffler, a fiber mesh can be used to prevent the airflow from passing through the muffler quickly. In other words, the flow path for compressed air inside the muffler can be extended by the fiber mesh, wherein the noise reduction performance mainly depends on the density and structure of the fiber mesh.

[0005] This is already known from WO 2019 / 063350 A1, which discloses a silencer for a compressed air system, in particular for a brake system of a utility vehicle. The silencer comprises a housing having an inlet channel for a compressed air flow and a chamber for receiving a sound-absorbing material. The inlet channel and the chamber are separated perpendicularly to the compressed air flow by a separation plate, which has a plurality of openings in the peripheral region of the compressed air flow for introducing the compressed air into the chamber. In the chamber of the silencer, a sound-absorbing fiber material having a knitted, braided or woven structure or pattern can be used, or alternatively, a granular material can be used.

[0006] Therefore, silencers of the prior art use a fiber grid in their housing which in principle has a uniform structure or density, ie the spacing between the woven or knitted fibers is constant.

[0007] However, a sound damper for discharging compressed air from a valve of a compressed air treatment system of a motor vehicle and for attenuating outflow noise is known from WO 2017 / 009445 A1. The sound damper comprises a housing having at least one inlet opening and at least one outlet opening, and a noise reduction material arranged in the housing between the at least one inlet opening and the at least one outlet opening, the purpose of which is to reduce the flow noise of the compressed air expanding in the housing and flowing through the noise reduction material. In order to reduce noise emissions, the noise reduction material has a higher packing density in a central area adjacent to the at least one inlet opening than in an outer area adjacent to the at least one outlet opening. However, the production of such a noise reduction material with a gradient density is complex and expensive.

[0008] The object of the present invention is therefore to improve a silencer as described above, in particular to increase the silencer performance and at the same time to facilitate its production. Summary of the invention

[0009] According to the invention, this object is solved by a silencer according to the features of claim 1. Accordingly, a silencer is provided for a compressed air system, in particular for a brake system of a utility vehicle, comprising at least one fiber mesh roll unit having at least two mesh density regions, at least one inlet, at least one outlet and a housing. The at least one fiber mesh roll unit is accommodated in the housing of the silencer to attenuate noise emissions of air flowing through from the at least one inlet to the at least one outlet.

[0010] The invention is based on the basic idea that the density of the fiber mesh contained in the silencer housing is partially increased in the direction of the air flow, which leads to an increase in the sound-absorbing performance, but without impairing the function of the silencer due to trapped air, i.e. without causing air to accumulate to such an extent that the flow resistance is too great. In other words, by using areas of different fiber mesh density, the flow resistance can be appropriately balanced, while the fiber mesh retains the increased sound-absorbing performance due to the higher density areas.

[0011] It can also be provided that at least one fiber mesh roll unit is made of thermoplastic fibers. The flexibility or softness of thermoplastic fibers allows them to be knitted or woven.

[0012] Furthermore, at least one fiber mesh roll unit may be knitted and / or woven.

[0013] Knitting allows to create a grid structure or pattern by connecting or interlocking fiber loops, where the loop size can be used to adjust the grid density and thereby also the flow resistance of the knitted fiber grid. Knitting creates fiber loops in rows, which has the advantage that a flattened or tubular grid can be achieved. The fibers in the rows in a knitted grid follow a serpentine path, forming symmetrical loops symmetrically above and below the average path of the weaving threads. These serpentine loops can be easily stretched in different directions, making the knitted grid highly elastic.

[0014] It is well known that knitting machines or automated machines used in industry generate tubular or tube-like shaped fiber meshes due to their circular manufacturing process or direction. The tubular shape is the starting point for further preparation of the knitted fiber mesh, where the tubular shape is flattened and rolled up in a controlled manner to be inserted or housed in a silencer, muffler or sound attenuator.

[0015] In the case of weaving, on the other hand, two different sets of fibers are interwoven at right angles to form a mesh, resulting in a rigid and substantially shape-retaining mesh that is easy to process and, in particular, can be processed at higher machine speeds than other manufacturing techniques, depending on fiber strength.

[0016] Both knitting and weaving preferably result in an approximately uniform fiber pattern in each mesh density region.

[0017] Furthermore, at least one fiber mesh roll can include at least one first mesh density region and at least one second mesh density region, wherein the density of at least one first mesh density region is lower than the density of at least one second mesh density region. The different densities ensure effective noise reduction on the one hand and ensure that compressed air can still flow through on the other hand.

[0018] Furthermore, it is conceivable that at least one first mesh density region and at least one second mesh density region are arranged alternately in the circumferential direction of the tubular shape of the fiber mesh. As a result, the air flowing through is more strongly obstructed at set, substantially equidistant distances than in the middle regions, and the obstruction to the air flow is therefore distributed over the entire height of the silencer chamber.

[0019] It is also possible to arrange at least one first mesh density region near at least one inlet and at least one second mesh density region near at least one outlet so that air flowing through the muffler first passes through at least one first mesh density region of at least one fiber mesh roll unit and then passes through at least one second mesh density region of at least one fiber mesh roll unit. Arranging a mesh region with a higher density near or around at least one outlet can improve the sound-absorbing performance.

[0020] With reference to the airflow direction, the extension dimensions of the first mesh density region and the second mesh density region may be the same or different.

[0021] It is also conceivable that a plurality of at least one first mesh density area and a plurality of at least one second mesh density area are arranged alternately in a direction from at least one inlet of the muffler to at least one outlet of the muffler. In this way, the mesh areas with higher density are distributed along the entire length of the housing in the direction of the air flow, which gradually or stepwise reduces the noise.

[0022] In the case of an alternating arrangement, it is also conceivable that, with reference to the airflow direction, the extension dimensions of the mesh regions with a lower density successively decrease, while, on the contrary, the extension dimensions of the mesh regions with a higher density increase.

[0023] The fiber mesh roll unit may also include at least one third mesh density region having a higher density than the second mesh density region, wherein at least one first mesh density region, at least one second mesh density region and at least one third mesh density region are arranged in a density increasing manner in the direction from at least one inlet to at least one outlet. This causes the air flowing through the silencer to be increasingly obstructed in the direction toward the outlet. With the gradual increase in the density of consecutive regions in the reference air flow direction, (excessive) strong deceleration can be avoided at the transition between adjacent regions.

[0024] Furthermore, at least one fiber mesh roll unit may include a rolled fiber mesh having at least two mesh density regions; or include a plurality of stacked rolled fiber meshes, each having a mesh density. Depending on the production settings, a fiber mesh roll unit having different mesh density regions may be produced, for example, by knitting, wherein the different mesh density regions are obtained by setting the needles along the circumference of the circular knitting machine. On the other hand, a fiber mesh roll unit may be generated by stacking fiber mesh rolls one on top of another, wherein each fiber mesh roll has its own mesh density.

[0025] Since the silencer mostly has an inner diameter of a circular shape, it is obvious that the fiber mesh roll unit is housed or placed in the housing of the silencer, wherein the rolling direction is perpendicular to the air flow direction.

[0026] It is also conceivable that the stacked rolled fiber grids are connected to each other. This can be achieved by various known connection techniques suitable for thermoplastic fibers (such as bonding, heat melting or sewing, etc.).

[0027] The object of the present invention can also be solved by a method for producing a fiber mesh roll unit for a silencer for a compressed air system, in particular for a brake system of a utility vehicle, wherein the silencer comprises at least one inlet, at least one outlet and a housing, and wherein the method comprises the following steps:

[0028] -- knitting a tubular fiber mesh by thermoplastic fibers so as to form at least two regions of different mesh densities;

[0029] --Controlled flattening of a tubular fiber mesh; and

[0030] --Wound flat tubular fibers;

[0031] Therein, at least two mesh density areas are arranged in a manner of increasing density or in an alternating manner with respect to a flow direction of air flowing through the silencer.

[0032] In order to obtain a tubular shape, the fiber mesh is circularly knitted by means of a corresponding knitting device, tool, machine or automated machine. Such a device comprises circularly arranged knitting needles, wherein the mesh density of the fiber mesh can be adjusted by the distribution of the needles of the device. Thus, needles arranged more closely along the needle loops of the knitting device create corresponding mesh areas with a higher density. The knitted fiber mesh is then flattened, for example between two rollers, wherein the feed of the flattening device is controlled to adjust the circumferential orientation of the fiber mesh tube. This control ensures that the arrangement of the different mesh density areas of the flattened and rolled-up fiber mesh corresponds to the predetermined arrangement of the fiber mesh roll unit so as to be accommodated in the housing of the silencer.

[0033] The advantage of this method is that a coherent fiber mesh tube is created which already has the desired order of mesh density regions arranged around the circumference.

[0034] The invention also relates to a method for producing a fiber mesh roll unit for a silencer for a compressed air system, in particular for a brake system of a utility vehicle, wherein the method comprises the following steps:

[0035] --knitting and / or weaving a plurality of fiber meshes by thermoplastic fibers, each fiber mesh having at least one mesh density;

[0036] -- winding the fiber mesh to form a fiber mesh roll; and

[0037] -- stacking the rolled fiber mesh to form a fiber mesh roll unit having at least two mesh density regions;

[0038] Therein, at least two mesh density areas are arranged in a manner of increasing density or in an alternating manner with respect to a flow direction of air flowing through the silencer.

[0039] The fiber grids can be knitted or woven from thermoplastic fibers, wherein the respective fiber grid has an individual, preferably uniform, grid density. Each fiber grid is then rolled up to form a roll, wherein the knitted fiber grids often still have to be flattened first. Thereafter, the various rolled fiber grids are stacked one above the other, wherein the order corresponds to the predetermined order of the grid densities.

[0040] The advantage of this method is that fiber mesh rolls of different densities can be produced in parallel in multiple machines and then stacked to form a fiber mesh roll unit.

[0041] The method may further comprise the step of connecting the rolled-up fiber meshes to each other, wherein typical connection techniques for thermoplastic fibers may be applied, such as gluing, heat-melting, sewing, etc.

[0042] All structural and functional features described above in connection with the fiber mesh according to the invention and its possible embodiments can also be provided, individually or in combination, by one of the methods for producing a fiber mesh roll unit according to the invention and the associated advantages can also be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further details and advantages of the present invention are now disclosed in embodiments according to the present invention in conjunction with the accompanying drawings.

[0044] In the attached picture:

[0045] Figure 1 A cross-sectional view showing an embodiment of a prior art muffler;

[0046] Figure 2 Shows Figure 1 A cross-sectional view of a lower housing of an embodiment of the present invention;

[0047] Figure 3 shows a cross-sectional view of a lower housing of a silencer according to the present invention, the silencer comprising a first embodiment of a fiber mesh roll unit;

[0048] Figure 4 Shows Figure 3 A schematic diagram of a first embodiment of a knitted fiber mesh roll unit;

[0049] Figure 5 A schematic diagram showing a second embodiment of a woven fiber mesh roll unit;

[0050] Figure 6 A schematic diagram showing a third embodiment of a knitted fiber mesh roll unit;

[0051] Figure 7 shows a schematic diagram of a fourth embodiment of a woven fiber mesh roll unit;

[0052] Figure 8shows a schematic diagram of a fifth embodiment of a knitted fiber mesh roll unit;

[0053] Fig. 9 shows a schematic diagram of a sixth embodiment of a woven fiber mesh roll unit;

[0054] Fig.10 An embodiment of a method for producing a fiber mesh roll unit according to the present invention is shown;

[0055] Fig.11 Shows Fig.10 a schematic diagram of the steps of the method; and

[0056] Fig.12 An embodiment of another method of producing a fiber mesh roll unit according to the present invention is shown. DETAILED DESCRIPTION

[0057] In order to better distinguish different embodiments and the prior art, the same or corresponding elements are all denoted by 100 in the corresponding reference numerals of the drawings.

[0058] Figure 1 A cross-sectional view of an embodiment of a prior art muffler 10 is shown.

[0059] The muffler 10 includes an upper shell 12 and a lower shell 14, each of which encloses a chamber 16. The muffler 10 also includes an air inlet 18 and an air outlet 20, wherein compressed air 22 flows from the air inlet 18 to the air outlet 20.

[0060] exist Figure 2 In the embodiment of the invention, only the lower shell 14 is shown, which contains the sound-absorbing material in the form of a fiber mesh 24 having a uniform structure. This means that the air flow is generally obstructed, but the transmission of noise is not effectively reduced.

[0061] In contrast, Figure 3 The lower housing 114 of the silencer 100 according to the invention is shown housing a first embodiment of a fiber mesh roll unit 124 through which the compressed air 122 flows from top to bottom.

[0062] Figure 4 Further details are shown Figure 3 The fiber mesh roll unit 124, wherein the flow of compressed air 122 is from left to right.

[0063] Figure 4 The fiber mesh of the fiber mesh roll unit 124 is knitted, ie, a plurality of rows 126 (each row 126 including a plurality of loops 128 ) are connected or interlocked, wherein each loop 128 is connected to adjacent loops 128 of the previous and next rows 126 .

[0064] The ring row 126 is made of thermoplastic fibers 129 .

[0065] Figure 4 An advantage of the knitted fiber mesh 124 is that, due to its loops 128, it is stretchable.

[0066] also, Figure 4 The fiber mesh has a first mesh density region 130 and a second mesh density region 132 , wherein the mesh density can be adjusted by the size of the ring 128 .

[0067] The mesh density of the first mesh density region 130 is lower than the mesh density of the second mesh density region 132 .

[0068] Therefore, passing air 122 is increasingly obstructed when flowing from left to right, ie, when moving from first mesh density region 130 to second mesh density region 132 .

[0069] The fiber mesh roll unit 124 may be formed of a single knitted fiber mesh tube having a first mesh density region 130 and a second mesh density region 132, or may be formed of two stacked fiber mesh rolls, wherein the upper fiber mesh roll forms the first mesh density region 130 of the fiber mesh roll unit 124 and the lower fiber mesh roll forms the second mesh density region 132 of the fiber mesh roll unit 124. The same applies to the following embodiments.

[0070] Figure 5 A second embodiment of a fiber mesh roll unit 224 according to the present invention is shown in FIG. The fiber mesh 224 is woven, that is, the thermoplastic fibers are interwoven perpendicularly to each other. Figure 4 This provides greater rigidity to the fiber mesh 224 in comparison.

[0071] The fiber mesh roll unit 224 further includes a first mesh density region 230, which is first arranged in the direction of the airflow 222, and a second mesh density region 232. Therefore, likewise, the flowing air 222 is increasingly obstructed, resulting in higher sound-absorbing performance.

[0072] Figure 6 3. A third embodiment of a fiber mesh roll unit 324 according to the present invention is shown in FIG. The fiber mesh 324 is knitted and includes a plurality of first mesh density regions 330 and a plurality of second mesh density regions 332, wherein the first mesh density regions 330 and the second mesh density regions 332 are alternately arranged in the direction of the airflow 322.

[0073] Referring to the airflow 322, the grid density regions 330, 332 extend less than Figure 4 Thus, the airflow 322 is slowed down in an alternating manner, ie after a set, substantially equidistant distance, the airflow is more obstructed than in the middle region.

[0074] For Figure 7 The same is true for the fourth embodiment of the fiber mesh 424 according to the present invention shown in FIG. The fiber mesh roll unit 424 is as Figure 5 The fiber mesh roll unit 224 is woven like this.

[0075] exist Figure 8 and Fig. 9 Another order of grid density regions is shown in FIG. 1 , wherein the order shown can be understood as respectively according to Figure 4 and Figure 5 A continuation or extension of a sequence.

[0076] exist Figure 8 In FIG. 5 , a fifth embodiment of a fiber mesh roll unit 524 according to the present invention is shown, and in FIG. Fig. 9 , a sixth embodiment of a fiber mesh roll unit 624 according to the present invention is shown.

[0077] Likewise, the two fiber grids 524, 624 differ in manufacturing technique in that the fiber grid roll unit 524 is knitted, whereas the fiber grid roll unit 624 is woven.

[0078] Both fiber mesh roll units 524, 624 include a first mesh density region 530, 630, a second mesh density region 532, 632, and a third mesh density region 534, 634, wherein these three regions are arranged in a manner of increasing mesh density with reference to the airflow 522, 622. Therefore, the airflow 522, 622 is increasingly obstructed, wherein the density difference from one mesh density region to the next mesh density region is Figure 4 and Figure 5 The embodiment is smaller than that of FIG.

[0079] exist Fig.10 In FIG. 7 , an embodiment of a method 700 for producing a fiber mesh roll unit for a silencer for a compressed air system according to the present invention is shown.

[0080] also, Fig.11 It is shown in Fig.10 Some of the steps in .

[0081] In a first method step 702 , a tubular fiber mesh 704 is knitted out of thermoplastic fibers 706 .

[0082] In order to obtain the tubular shape, the fiber grid 704 is knitted in an annular manner by a corresponding knitting device. Such a device comprises knitting needles arranged in an annular manner, wherein the grid density of the fiber grid 704 can be adjusted by the distribution of the needles of the device. Thus, needles arranged more closely along the needle loop of the knitting device create corresponding grid areas with higher density.

[0083] In the knitting device, a fiber grid 704 is produced in direction L.

[0084] The obtained tubular mesh 704 has the same Figures 3 to 8 The described embodiments of the fiber mesh have the same advantages and structural and functional features, in particular at least two regions of different mesh density.

[0085] In a second method step 708, the knitted tubular fiber mesh 704 is flattened. This can be achieved primarily by passing the tubular mesh 704 between two rollers or cylinders in the direction L. The flattening is controlled by adjusting the orientation before passing through the rollers so that the arrangement of the mesh density areas after flattening corresponds to the predetermined arrangement of the mesh density areas. In this way, a double-layer mesh belt 710 is obtained.

[0086] In a third method step 712 , the flattened tubular mesh or double-layer mesh strip 710 is wound around an axis perpendicular to the production direction L, thereby obtaining a roll 714 of the knitted and flattened fiber mesh.

[0087] The roll 714 of flattened tubular fiber mesh 704 is housed within the muffler such that regions of different mesh density are aligned in a manner such that density increases or alternates in the direction of flow of the passing compressed air.

[0088] exist Fig.12 , another method 800 of producing a fiber mesh roll unit is shown.

[0089] In a first method step 802 , a first fiber mesh of a first mesh density is woven and / or knitted out of thermoplastic fibers. Thereafter, in a second method step 804 , the first fiber mesh is rolled up.

[0090] Separately, and possibly in parallel, in a third method step 806 , a second fiber mesh of a second mesh density is likewise woven and / or knitted from thermoplastic fibers. Likewise, in a fourth method step 808 , the second fiber mesh is rolled up.

[0091] Finally, in a fifth method step 810 , the first fiber mesh roll and the second fiber mesh roll are stacked and placed in a housing of the silencer.

[0092] Reference numerals list

[0093] 10. Silencer

[0094] 12 Upper shell

[0095] 14, 114 lower shell

[0096] 16 Chamber

[0097] 18 Air Inlet

[0098] 20, 120 air outlet

[0099] 22, 122, 222, 322, 422, 522, 622 airflow

[0100] 24 Fiber Mesh

[0101] 100 Silencer

[0102] 124, 324, 524, 704 knitted fiber mesh roll units

[0103] 224, 424, 624 Woven Fiber Mesh Roll Units

[0104] 126 Ring

[0105] 128 rows

[0106] 129, 706 Thermoplastic Fiber

[0107] 130, 230, 330, 430, 530, 630 First grid density area

[0108] 132, 232, 332, 432, 532, 632 Second grid density area

[0109] 534, 634 Third grid density area

[0110] 700 The first method for producing fiber mesh

[0111] 702 First Method Step

[0112] 704 Tubular Grid

[0113] 708 Second method step

[0114] 710 Double Layer Grid Belt

[0115] 712 Third Method Step

[0116] 714 Fiber Mesh Roll

[0117] 800 Second method for producing fiber mesh

[0118] 802 First method step

[0119] 804 Second method step

[0120] 806 Third method step

[0121] 808 Fourth method step

[0122] 810 Fifth method step

[0123] L Production direction

Claims

1. A silencer (100) for a compressed air system, in particular for a brake system of a utility vehicle, the silencer (100) comprising at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624), the fiber mesh roll unit having at least two mesh density regions (130, 132, 230, 232, 330, 332, 430, 432, 530, 532, 534, 630, 632, 634), at least one inlet, at least one outlet (120) and a housing, wherein: At least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) is housed within a housing of the muffler (100) to attenuate noise emissions from air flowing through from at least one inlet to at least one outlet (120).

2. The silencer (100) according to claim 1, characterized in that: The at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) is made of thermoplastic fibers.

3. The silencer (100) according to claim 1 or 2, characterized in that: The at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) is knitted and / or woven.

4. The silencer (100) according to any one of the preceding claims, characterized in that The at least one fiber mesh roll unit (124, 224, 324, 424) includes at least one first mesh density region (130, 230, 330, 430) and at least one second mesh density region (132, 232, 332, 432), wherein the density of the at least one first mesh density region (130, 230, 330, 430) is lower than the density of the at least one second mesh density region (132, 232, 332, 432).

5. The silencer (100) according to claim 4, characterized in that: The at least one first mesh density region (130, 230, 330, 430) is arranged near the at least one inlet, and the at least one second mesh density region (132, 232, 332, 432) is arranged near the at least one outlet (120), so that air flowing through the silencer (100) first passes through the at least one first mesh density region (130, 230, 330, 430) of the at least one fiber mesh roll unit (124, 224, 324, 424), and then passes through the at least one second mesh density region (132, 232, 332, 432) of the at least one fiber mesh roll unit (124, 224, 324, 424).

6. The silencer (100) according to claim 4, characterized in that: The at least one first mesh density region (130, 230, 330, 430) and the at least one second mesh density region (132, 232, 332, 432) are alternately arranged in a direction from the at least one inlet to the at least one outlet (120) of the muffler (100).

7. The silencer (100) according to any one of claims 1 to 4, characterized in that: The fiber mesh roll unit (524, 624) further comprises at least one third mesh density region (534, 634), the third mesh density region having a higher density than the second mesh density region (532, 632), wherein the at least one first mesh density region, the at least one second mesh density region and the at least one third mesh density region (530, 532, 534, 630, 632, 634) are arranged in a manner of increasing density in a direction from the at least one inlet to the at least one outlet (120).

8. The silencer (100) according to any one of the preceding claims, characterized in that The at least one fiber mesh roll unit (124, 224, 324, 424, 524, 624) comprises: a rolled fiber mesh having at least two mesh density regions (130, 132, 230, 232, 330, 332, 430, 432, 530, 532, 534, 630, 632, 634); or a plurality of stacked rolled fiber meshes, each fiber mesh having a mesh density region (130, 132, 230, 232, 330, 332, 430, 432, 530, 532, 534, 630, 632, 634).

9. The silencer (100) according to claim 8, characterized in that: The rolling direction is perpendicular to the direction of air flowing through the silencer (100).

10. The silencer (100) according to claim 8 or 9, characterized in that: The stacked rolled fiber grids are connected to each other.

11. A method (700) for producing a fiber mesh roll unit (124, 224, 324, 424, 524, 624) for a silencer (100) for a compressed air system, in particular for a brake system of a utility vehicle, wherein: The muffler (100) comprises at least one inlet, at least one outlet (120) and a housing, and wherein the method (700) comprises the following steps: - knitting (702) a tubular fiber mesh (704) by means of thermoplastic fibers (706) so as to form at least two regions having different mesh densities; -- controlled flattening (708) of the tubular fiber mesh (704); and -- Winding (712) the flattened tubular fiber mesh (704); Wherein, at least two mesh density areas are arranged in a manner of increasing density or in an alternating manner with respect to a flow direction of air flowing through the silencer (100).

12. A method (800) for producing a fiber mesh roll unit (124, 224, 324, 424, 524, 624) for a silencer (100) for a compressed air system, in particular for a brake system of a utility vehicle, wherein: The method comprises the following steps: -- Knitting and / or weaving a plurality of fiber meshes by thermoplastic fibers, each fiber mesh having at least one mesh density; -- winding (804, 808) the fiber mesh to form a fiber mesh roll; and -- stacking (810) the rolled fiber mesh to form a fiber mesh roll unit having at least two mesh density regions; Wherein, at least two mesh density areas are arranged in a manner of increasing density or in an alternating manner with respect to a flow direction of air flowing through the silencer (100).

13. The method (800) of claim 12, further comprising the step of interconnecting the rolled fiber meshes.

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