AT9713U1 - COMPRESSED AIR MUFFLER FOR PNEUMATIC APPLICATIONS - Google Patents

Description

2 AT 009 713 U1

The invention relates to a pneumatic silencer for pneumatic applications, with a housing closed except for an air inlet and an air outlet, which encloses a sound absorption device, which is penetrated by an air duct connecting the air inlet with the air outlet.

A compressed air silencer of this type known from DE 20 2004 005 746 U1 contains a housing enclosing a sound absorption device, which is closed apart from an air inlet provided at one end and an air outlet provided at the other end. The existing example of a porous material or a foam sound absorption device is penetrated by a perforated air duct, which defines a the air inlet to the air outlet connecting air duct. In operation, the compressed air silencer is connected in the region of its air inlet to a pneumatic device, for example to the output of an ejector, and causes a damping of the outflow noise of the compressed air. The sound-damping effect is predominantly based on absorption of the sound energy in the sound absorbing device made of suitable material.

A known from DE 202 05 068 U1 pneumatic muffler consists of a porous muffler body, which defines a conically tapering to the air outlet air duct and is completely uncovered on the outer circumference. Due to the narrowing flow cross-section, the compressed air is forced to flow through the muffler body.

A compressed air silencer described in EP 1 155 242 B1 differs from the aforementioned, inter alia, in that the silencer body is closed on the circumference and is uncovered only at the end surface bounding the air outlet.

The frequency ranges of the sound to be damped can vary greatly depending on the application. Sometimes it's the rather low and sometimes the higher frequencies that come with a very high sound pressure level. In order to take account of these different conditions which are not exhaustively listed, DE 20 2004 005 746 U1 has already proposed changing the flow cross-section of the air-guiding channel available to the compressed air by inserting one or more constriction tubes. However, this specific adaptation is relatively expensive.

It is the object of the present invention to propose measures that allow a simpler way a sound attenuation at different frequency ranges.

To achieve this object, it is provided in a compressed air silencer of the type mentioned that the sound absorption device has a plurality of different absorption zones in their frequency-dependent sound damping properties.

One and the same compressed air silencer is now able to make an effective sound attenuation within a very wide frequency spectrum. While previous mufflers usually perform a particularly effective sound absorption only within a fairly narrow frequency range, now a very broadband frequency attenuation can be guaranteed without lowering the cutoff frequency from which the muffler loses its effect. Thus, in many cases, one and the same silencer can be used for different applications in which previously had to resort to different mufflers. In addition, the sound attenuation in one and the same application is much more effective than before, which brings the additional advantage that can be comparable to the prior art sound attenuation intensity with a much shortened silencer bring about. With the pneumatic muffler equipped pneumatic devices can therefore be realized with a total of more compact dimensions. 3 AT 009 713 U1

Advantageous developments of the invention will become apparent from the dependent claims.

The sound absorption device expediently has a sleeve-like shape, wherein it coaxially surrounds the air duct, which preferably has a straight course. 5

In order to provide the compressed air a friction-free flow and at the same time to ensure optimum access to the sound absorption device for sound waves, a perforated wall expediently air duct is provided to define the air duct, which is umslos sen of the sound absorption device, the latter in a preferably coaxial manner ,

It has proven to be advantageous to design the sound absorption device such that the different absorption zones are arranged in succession in the longitudinal direction of the air duct. With the " different absorption zones " is meant by voneinan-15 the deviating frequency-dependent sound damping properties having absorption zones.

A particularly simple design of the damping system is possible if, within the individual absorption zones over the entire radially measured zone thickness, the same frequency-dependent sound damping properties are present. The different absorption zones can be formed by successive lengths of the sound absorption device.

The sound absorbing means may be formed by a single integral sound absorbing body having a sleeve-like configuration. However, it is particularly simple to realize absorption zones with different sound attenuation intensity by building up the sound absorption device from a plurality of individual sound absorption bodies juxtaposed in the longitudinal direction of the air duct. These can lie directly against one another without having a firm connection. Preferably, they are formed as a ring body, with the air duct as the center.

The different sound damping properties can be realized for example by using different sound damping materials. This solution is particularly simple in connection with a sound absorption device composed of several sound absorption bodies, since here one only has to resort to sound absorption bodies differing in the material which are combined as desired.

Alternatively, or in addition to using different sound attenuation materials, the absorption zones of different sound attenuation properties can also be realized through the use of sound attenuation materials that inherently have different material densities. For example, it would be possible here to use fiber-material bodies of different degrees of compression. 45 The simplest solution from today's point of view for realizing the different frequency-dependent sound damping properties is to provide measures which cause the sound-deadening material to be radially differently compressed over the length of the sound absorption device. This can be used for all absorption zones on one and the same sound damping material. 50

The different degrees of radial compression can be achieved very easily, in particular, by providing a contour which changes in the longitudinal direction of the muffler for the receiving device receiving the sound absorption device, radially outwardly from the peripheral wall of the housing and radially inward from an air guide tube. For example, this annular receiving space can have a cross-section that changes in the longitudinal direction, so that the radial compression increases, or decreases, from one end to the other of the sound absorption device, in particular continuously.

Such a design is achieved in particular by the use of an externally conically shaped air guide tube in conjunction with a circular cylindrical inner surface having peripheral wall of the housing. However, the conicity can also be laid in the inner surface of the peripheral wall.

In order to achieve different Verpressungsgrade in connection with a cylindrical design of both the air duct and io the peripheral wall, one uses to realize the different absorption zones expediently single, successively arranged sound absorption body having different radial wall thicknesses in their initial state, before insertion into the receiving space , and which are therefore radially different degrees of compression after installation. 15

The number of different absorption zones is basically arbitrary. So far, very good experiences have been made with a standard length having compressed air silencer, especially in conjunction with three successive different absorption zones. 20

The different absorption zones can be equal to each other. In order to prefer more or less certain frequency ranges in the attenuation, but also in their length differing absorption zones may be present. 25 The invention will be explained in more detail with reference to the accompanying drawings. In this show:

Figure 1 is a composed of a dash-dotted lines indicated pneumatic device and a compressed air silencer according to the invention composed pneumatic device 30 see preferred structure, wherein the compressed air silencer is shown in longitudinal section, and

Figure 2 shows another possible embodiment of the compressed air silencer in longitudinal section. 35 A dashed line of the drawing shows a part of a pneumatic device 1 which, during its operation, flows through compressed air which leaves the device 1 via an outlet channel 2. The pneumatic device 1 can be, for example, a valve or an ejector device that can be replaced to generate negative pressure. This list is not meant to be exhaustive. 40

In order to dampen the noise of the compressed air flowing out through the outlet channel 2, an inventive compressed air silencer 3 is connected to the end section of the outlet channel 2. This has at one end a mounting portion 4, which is particularly suitable for releasable attachment to the pneumatic device 1. By way of example, it is designed as a thread section having an external thread, which can be screwed detachably into the end section of the outlet channel 2 provided with a complementary internal thread.

In the following, for simplicity's sake, only as " muffler " designated compressed air sound absorber 3 preferably has an elongated shape, wherein at one end, in the region of the attachment portion 4, an air inlet 5 and the other end has an air outlet 6. Its outer shape is expediently substantially cylindrical.

The air inlet 5 and the air outlet 6 are predetermined by a housing 7 defining the outer contour of the silencer 55 3. This is, apart from the air inlet 5 and 5 AT 009 713 U1 the air outlet 6, closed. It has a substantially sleeve-shaped peripheral wall 8 and two end walls 12, 13. The one, first end wall 12 is penetrated by the air inlet 5 and has the attachment portion 4. The axially opposite second end wall 13 is penetrated by the air outlet 6.

In the interior of the housing 7 extends, in particular straight, a the air inlet 5 with the air outlet 6 connecting air duct 14. This is preferably formed from the interior of an air duct 15 shown cut only in Figure 2, the one end for centering on the first end wall 12 and the other end the second end wall 13 can be fixed.

The compressed air arising in the operation of the pneumatic device 1 enters the air inlet 5 of the silencer 3, then flows through the air duct 14 and exits through the air outlet 6 to the atmosphere.

It is possible to form the silencer 3 in such a way that on the second end wall 13 another, preferably designed according to the principles of the invention muffler can be attached. This allows very simple variations in the overall length. In this case, the compressed air flowing out through the air outlet 6 would flow into the subsequent muffler and only leave the muffler assembly afterwards. The number of stackable silencers is basically arbitrary.

Due to a smooth-surfaced design of the inner surface of the air duct 15, the compressed air can flow through the muffler 3 with little loss.

The outer diameter of the air guide tube 15 is smaller than the inner diameter of the sleeve-shaped, in the embodiment substantially hollow cylindrical peripheral wall 8. This is between the radially outwardly facing outer peripheral surface 16 of the air guide tube 15 and the radially inwardly facing inner peripheral surface 17 of the peripheral wall 8 an annular cross-section exhibiting Recording room 18 is formed. This receiving space 18 is filled by a total designated by reference numeral 22 sound absorption device. This consists of a material with sound-absorbing properties, which is simply referred to as sound damping material.

The wall of the air guide tube 15 is perforated and has a plurality of radially continuous wall openings 23. These wall openings 23 allow the sound waves a passage through the pipe wall and thus an entrance and exit into and out of the sound absorption device 22. Within the sound absorption device 22 sound energy is absorbed and thereby lowered the noise level. Further details on the sound-damping process can be found in DE 20 2004 005 746 U1, so that details are omitted here.

As the compressed air flows through the muffler 3, there is practically a " separation " of compressed air flow and sound waves instead. The compressed air flows largely undisturbed alone in the interior of the air duct 14 and does not or only slightly into the sound absorption device 22 on.

The peculiarity of the sound absorption device 22 is that it has a plurality of different in their frequency-dependent sound damping properties absorption zones 24. The individual " different absorption zones 24 " So they are coordinated so that they have their optimal Frequenzdämpfungsvermögen in different frequency ranges. As a result, the sound absorption device 22 as a whole can be designed such that it has a high sound absorption capacity in an extremely broadband frequency range. The silencer 3 is therefore able to attenuate the sound produced by the outflowing compressed air much more effective than 6 AT 009 713 U1

Designs of the prior art, which have only a narrow optimal frequency attenuation spectrum. In addition, the muffler 3 can be used for a variety of pneumatic applications in which previously had to be used a plurality of differently designed mufflers. 5

Although hereinafter referred to as " different absorption zones " designated absorption zones 24 different Frequenzdämpfungsvermögens over the volume of the sound absorbing device 22 may be distributed - even in the radial direction several such absorption zones 24 could be arranged side by side - recommends the io embodiments Realisiere with successively arranged in the longitudinal direction of the air duct 14 different absorption zones 24th The longitudinal axis of the air duct 14 is indicated at 25 in phantom.

Overall, the sound absorption device 22 preferably has a sleeve-like shape, 15 wherein it surrounds the air duct 15 and therefore also the air duct 14 located therein coaxially.

All embodiments furthermore have in common that the different absorption zones 24 are formed by successive longitudinal sections of the sound absorption device 22 20. Within a respective absorption zone 24, the same frequency-dependent sound damping properties are consistently present in the thickness direction with respect to the longitudinal axis 25.

Preferably, the sound absorption device 22 is composed of a plurality of individual, in the longitudinal direction of the air duct 14 juxtaposed sound absorption bodies 26 together. They can be successively inserted into the receiving space 18 during assembly. In the assembled state, they are held immobile in the receiving space 18 by the entire arrangement of sound absorbing bodies 26 at one end on the inner surface of the first end wall 12 and the other end on the inner surface of the second end wall 30 13 is supported.

The sound absorption body 26 are expediently annular, wherein they preferably have no interruption in their circumferential direction. In order to be able to optimally design the sound absorption device 22 with regard to the attenuation spectrum to be covered, the different absorption zones 24-which in the present case are formed by the individual sound absorption bodies 26-can have the same overall length between each other (FIG. 1) and, at least in part, have different lengths (Figure 2). 40

In the embodiment of Figure 1, the different frequency-dependent sound damping properties of the individual absorption zones 24 result using one and the same sound damping material due to a different strong radial compression. This is particularly easy to implement with a relatively easily deformable sound damping material, for example foam material or compressed fiber material. For example, polyurethane foam may be used as the foam material. Thus, the sound absorption device 22 can be realized in the form of one or more foam body. The radial compression differing from each other is obtained, in particular, by the fact that in the initial state identical thickness absorption sound absorbing bodies 26 are inserted into a receiving space 18 which has a cross section which varies over its overall length. The sound absorption device 22 is thus pressed less strongly radially in the areas of larger receiving space cross-section than in the 55 areas of smaller receiving space cross-section. The sound absorption device 22 is therefore radially biased to different extents at regions distributed over its length. From radially outward, the inner peripheral surface 17 of the peripheral wall 8 and from radially inward the outer circumferential wall 16 of the air guide tube 15 acts on the sound absorption device 22 in an impinging manner. 5

In order to obtain the receiving space cross section changing in the longitudinal direction, in the exemplary embodiment of FIG. 1, the inner circumferential surface 17 is circular-cylindrical, while the outer circumferential surface 16 of the air guiding tube 15 is conically tapered in the direction of the air outlet 6. The angle of inclination of the outer circumferential surface 16 assumed with respect to the longitudinal axis 25 is illustrated in FIG. 1 at 27.

Notwithstanding the arrangement of Figure 1, the tapering direction of the outer peripheral surface 16 could also be opposite, the air guide tube 15 so in the region of the air outlet 6 have a larger outer diameter than in the region of the air inlet 5. 15 Such a shape is indicated by dashed lines in Figure 2 at 28.

It is also possible to obtain the different degrees of radial prestressing of the sound absorption device 22 by resorting to an air guide tube 15 having a circular-cylindrical outer peripheral surface 16, as is the case in the exemplary embodiment of FIG. Here, as indicated by dash-dotted lines at 32 in FIG. 2, the circumferential wall 8 may have an inner peripheral surface tapering conically in one or the other axial direction. This results in practically a reversal of the geometrical relationships from FIG. 1. In principle, in order to achieve a receiving space cross section which varies in the longitudinal direction, both the outer peripheral surface 16 and the inner circumferential surface 17 can be provided with a noncircular shape.

In the embodiment of Figure 2, not only the air duct 15 has a 30 circular cylindrical outer peripheral surface 16, but also the inner peripheral surface 17 of the peripheral wall 8 is circular cylindrical. The ring cross section of the receiving space 18 is thus constant over the entire receiving space length.

The different radial compression of the sound absorption device 22 results in this exemplary embodiment from the fact that several sound absorption bodies 26 are used to form the various absorption zones 24, all of which have a radial wall thickness which is greater than in the initial state considered prior to installation in the receiving space 18 The radial width of the annular receiving space 18. In addition, the sound absorption body 26 differ from each other in the aforementioned radial Aus-40 gang wall thickness. If they are subsequently inserted according to FIG. 2 into the receiving space 18, they all experience a radial compression, which, however, also varies to a different degree due to the different output wall thickness.

In the figure 2, the initial dimensions of the individual sound absorption body 26 are indicated at 33 45 by dashed lines. Depending on the degree of compression, different frequency-dependent sound damping properties of the sound absorption device 22 result. In this way, a very simple, yet effective adaptation to the given application is possible. In order to form the different absorption zones 24, it is also possible to use a sound absorption device 22 consisting of different sound damping materials. This measure can be chosen as an alternative or in addition to the above-described measure of different degrees of compression. 55 It is also possible, in addition to or as an alternative to the above measures

Claims (24)

8 AT 009 713 U1 on sound damping material with different material density from home. In this case, one and the same different sound damping material can be used. The sound absorption device 2 may in particular be designed so that the material density and / or the degree of compression of the sound absorption device 22 increases starting from the air inlet 5 to the air outlet 6 - this is shown by way of example in Figure 1 - or decreases in this direction, as shown in Figure 2 is illustrated. The measures described can be implemented not only in a sound absorption device 22 composed of several axially successive sound absorption bodies 26, but also in one embodiment with a single sound absorption body functioning as a sound absorption device 22 and then having a corresponding length. This design is particularly useful in cases in which the under-15 different sound absorption properties caused by different degrees of radial compression of the material. For example, in the case of FIG. 1, where the individual sound absorption bodies 26 also have a varying compression over their length due to the conicity of the air guidance tube 15, then the sound absorption body 26 forming the entire sound absorption device 22 can vary in thickness over its length be radially compressed. This results in a continuous flow of a plurality of absorption zones 24 different frequency-dependent Schalldämpfungsvermögens. 25 Claims: 1. Compressed air muffler for pneumatic applications, with a closed except for an air inlet (5) and an air outlet (6) housing (7), which encloses a sound absorption device (22) by a the air inlet (5) the air outlet channel (6) connecting air duct (14) is interspersed, characterized in that the sound absorption device (22) has a plurality of different in their frequency-dependent sound damping properties absorption zones (24). 2. Compressed air silencer according to claim 1, characterized in that the sound absorption device (22) has a sleeve-like shape and surrounds the air duct (14) having a straight course coaxially. 3. Compressed air silencer according to claim 1 or 2, characterized in that the air duct (14) from the interior of a perforated wall having, from the sound absorbing means 40 (22) in particular coaxially enclosed air duct (15) is formed. 4. Compressed air silencer according to one of claims 1 to 3, characterized in that the different absorption zones (24) in the longitudinal direction of the air duct 45 (14) are arranged successively. 5. Compressed air silencer according to one of claims 1 to 4, characterized in that the different absorption zones (24) of successive longitudinal sections of the sound absorption device (22) are formed. 50 6. Compressed air silencer according to claim 4 or 5, characterized in that present within a respective absorption zone (24) of the sound absorption device (22) in the radial thickness direction consistently at least substantially the same frequency-dependent sound damping properties. 55 9 AT 009 713 U1 7. Compressed air silencer according to one of claims 1 to 6, characterized in that the different absorption zones (24) of individual, in the longitudinal direction of the air duct (14) juxtaposed sound absorption bodies (26) of the sound absorption device (22) are formed. 5 8. Compressed air silencer according to claim 7, characterized in that the sound absorption body (26) are annular. 9. Compressed air muffler according to one of claims 1 to 6, characterized in that io the different absorption zones (24) are formed by a single, the Schallabsorptionsein direction (22) in their entirety defining and preferably integral sound absorbing body. 10. Compressed air silencer according to one of claims 1 to 9, characterized in that 15 have the different absorption zones (24) in the longitudinal direction of the air duct (14) with each other the same length or a different length. 11. Compressed air silencer according to one of claims 1 to 10, characterized in that the sound absorption device (22) one or more foam body 20 summarizes. 12. Compressed air silencer according to one of claims 1 to 11, characterized in that the sound absorption device (22) comprises one or more pressed fiber material body. 25 13. Compressed air silencer according to one of claims 1 to 11, characterized in that the sound absorption device (22) for forming the different absorption zones (24) consists of different sound damping materials. 14. Compressed air silencer according to one of claims 1 to 13, characterized in that the sound absorption device (22) for forming the different absorption zones (24) consists of sound damping material with different material density. 15. Compressed air silencer according to one of claims 1 to 14, characterized in that the sound absorption device (22) for forming the different absorption zones (24) consists of different degrees radially compressed silencer material. 16. Compressed air silencer according to claim 15, characterized in that the different degrees pressed sound damping material is a foam material. 40 17. Compressed air silencer according to claim 15 or 16, characterized in that the sound absorption device (22) for obtaining the by different radial Ver-squeezing intensities auszeichnenden absorption zones (24) with different degrees of bias between the sound absorption device (22) peripherally surrounded 45th the peripheral wall (8) of the housing (7) and a the air duct (14) definie-generating air duct (15) is clamped. 18. Compressed air silencer according to claim 17, characterized in that in the initial state hollow cylindrical sound absorption device (22) on a conical 50 outer shape having air guide tube (15) sits. Compressed air muffler according to claim 18, characterized in that the peripheral wall (8) has a sound absorbing means (22) facing circular cylindrical inner peripheral surface (17). 55 10 AT 009 713 U1 20. Compressed air silencer according to one of claims 17 to 19, characterized in that a hollow cylindrical in the initial state sound absorption device (22) by a conical inner peripheral surface (17) having circumferential wall (8) of the housing (7) is enclosed. 5 21. Compressed air silencer according to claim 20, characterized in that the air guide tube (15) is designed outside circular cylindrical. 22. Compressed air silencer according to claim 17, characterized in that between the io peripheral wall (8) of the housing (7) and the air guide tube (15) on the Schallabsorpti onseinrichtung (22) receiving, over its length a constant annular cross-section exhibiting Receiving space (18) is defined, wherein the sound absorbing means (22) consists of a plurality of axially successive annular sound absorption bodies (26) which differ in their prior to insertion into the receiving space 15 (18) existing radial output wall thickness. 23. Compressed air silencer according to one of claims 14 to 22, characterized in that in the longitudinal direction of the air duct (14) successive absorption zones (24), the order of the absorption zones (24) is selected so that the material density and / or 20 the compression intensity increases or decreases from the air inlet (5) to the air outlet (6). Compressed air silencer according to one of claims 1 to 23, characterized in that the housing (7) in the region of the air inlet (5) has a fastening to a pneumatic device (1) enabling mounting portion (4). For this purpose 1 sheet of drawings 30 35 40 45 50 55