Device for reducing airborne and structure-borne sound

Abstract

A device for reducing airborne and structure-borne sound has a flow channel with a flow channel wall (22, 22′, 22″) and at least one resonator chamber (40, 40′, 40″) adjacent the flow channel wall (22, 22′, 22″). The flow channel wall is formed by a sound absorber (30, 30′, 30″) at least in a part bordering the resonator chamber (40, 40′, 40″). The sound absorber (30, 30′, 30″) is covered towards the resonator chamber (40, 40′, 40″) by an acoustically reflecting inner wall (42, 42′, 42″) of the resonator chamber with at least one wall aperture (44, 44′, 44″). Openings (32, 32′, 32″) completely covers the wall aperture (44, 44′, 44″) of the inner wall (42, 42′, 42″) of the resonator chamber such that sound waves flowing through the flow channel must pass the sound absorber (30, 30′, 30″) to enter the resonator chamber (40, 40′, 40″).

Claims

1. A device for reducing airborne and structure-borne sound (10, 10′, 10″), comprising a flow channel (20, 20′, 20″) with a flow channel wall (22, 22′, 22″) and at least one resonator chamber (40, 40′, 40″) adjacent to the flow channel wall (22, 22′, 22″), the flow channel wall (22, 22′, 22″) being formed by a sound absorber (30, 30′, 30″) at least in a part of the area bordering the resonator chamber (40, 40′, 40″), wherein the sound absorber (30, 30′, 30″) is covered towards the resonator chamber (40, 40′, 40″) by an acoustically reflecting inner wall (42, 42′, 42″) of the resonator chamber with at least one window (44, 44′, 44″) extending from the flow channel (20, 20′, 20″) to the at least one resonator chamber (40, 40′, 40″), wherein the sound absorber (30, 30′, 30″) is formed from a porous or fibrous material and is provided with straight openings (32, 32′, 32″) extending through the sound absorber (30, 30′, 30″) from the flow channel (20, 20′, 20″) to the at least one resonator chamber (40, 40′, 40″), and the sound absorber (30, 30′, 30″) that is provided with the straight openings (32, 32′, 32″) completely covers the window (44, 44′, 44″) of the inner wall (42, 42′, 42″) of the resonator chamber such that sound waves flowing through the flow channel (20, 20′, 20″) must pass the sound absorber (30, 30′, 30″) to enter the at least one resonator chamber (40, 40′, 40″).

2. The device of claim 1, wherein the inner wall of the resonator chamber (42, 42′) has exactly one window (44, 44′).

3. The device of claim 1, wherein the sound absorber (30, 30′, 30″) covers an area of the flow channel wall (22, 22′, 22″) that is larger than an area defined by the at least one window (44, 44′, 44″).

4. The device of claim 1, wherein the sound absorber (30, 30′, 30″) covers an area of the flow channel wall (22, 22′, 22″) that is at least twice as large as an area defined by the at least one window (44, 44′, 44″).

5. The device of claim 1, wherein the sound absorber (30, 30′, 30″) covers an area of the flow channel wall (22, 22′, 22″) that is at least three times as large as an area defined by the at least one window (44, 44′, 44″).

6. The device of claim 1, wherein the sound absorber (30, 30′, 30″) is formed from foam.

7. The device of claim 1, wherein the surface of the sound absorber (30, 30′, 30″) is roughened.

8. The device of claim 1, wherein the sound absorber (30) is covered with a fleece (34) towards the flow channel (20).

9. The device of claim 1, wherein the flow channel wall (22″) is formed concavely in its longitudinal direction (101″) at least in the area bordering the resonator chamber (40″) and forms an open channel.

10. A device for reducing airborne and structure-borne sound (10, 10′, 10″), comprising: a flow channel wall (22, 22′, 22″) with an inlet (24′), an outlet (24′) and a flow channel (20, 20′, 20″) extending between the inlet (24′) and the outlet (26′); a resonator chamber (40, 40′, 40″) adjacent to the flow channel wall (22, 22′, 22″) and external of the flow channel (20, 20′, 20″) so that a part of the flow channel wall (22, 22′, 22″) defines an acoustically reflecting inner wall (42, 42′, 42″) of the resonator chamber (40, 40′, 40″); a window (44, 44′, 44″) formed through the flow channel wall (22, 22′, 22″) and extending between the flow channel (20, 20′, 20″) and the at least one resonator chamber (40, 40′, 40″); and a sound absorber (30, 30′, 30″) disposed on a side of the flow channel wall (22, 22′, 22″) opposite the resonator chamber (40, 40′, 40″) and completely covering the window (44, 44′, 44″), the sound absorber (30, 30′, 30″) being formed from a porous or fibrous material and being provided with straight openings (32, 32′, 32″) extending from the flow channel (20, 20′, 20″) to the resonator chamber (40, 40′, 40″), wherein the sound absorber (30, 30′, 30″) accommodates sound waves flowing between the flow channel (20, 20′, 20″) and the at least one resonator chamber (40, 40′, 40″).

11. The device of claim 10, wherein a surface area of the flow channel wall (22, 22′, 22″) facing into the flow channel (20, 20′, 20″) includes a recess, the window (44, 44′, 44″) being formed through a part of the flow channel wall (22, 22′, 22″) having the recess, the sound absorber (30, 30′, 30″) being disposed in the recess.

12. The device of claim 10, wherein an area defined by the sound absorber (30, 30′, 30″) is larger than an area defined by the window (44, 44′, 44″).

13. The device of claim 10, wherein the straight openings (32, 32′, 32″) extending through the sound absorber (30, 30′, 30″) are aligned transverse to a longitudinal center line (201′) of the flow channel (20, 20′, 20″) extending between the inlet (24′) and the outlet (26′).

14. The device of claim 10, wherein each of the straight openings (32, 32′, 32″) defines a cross-sectional area that is smaller than a cross-sectional area of the window (44, 44′, 44″).

15. The device of claim 10, further comprising a fleece (34) covering a surface of the sound absorber (30) facing towards the flow channel (20).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a conceptual sectional representation of a device for reducing airborne and structure-borne sound according to the invention.

(2) FIG. 2 is a sectional side view of a device for reducing airborne and structure-borne sound according to the invention.

(3) FIG. 3 is a spatial representation of another device for reducing airborne and structure-borne sound according to the invention, cut along lines III-III of FIG. 4.

(4) FIG. 4 is a view of the embodiment of FIG. 3, cut along line IV-IV.

DETAILED DESCRIPTION

(5) Identical reference numbers in the Figures indicate identical or analogous elements.

(6) FIG. 1 shows a sectional view of a device according to the invention for reducing airborne and structure-borne sound 10. The device comprises a flow channel 20 with a flow channel wall 22 and a resonator chamber 40 adjacent to the flow channel wall 22. In the example shown, the flow channel wall 22 is formed in the entire area bordering the resonator chamber 40 by a sound absorber 30 with openings 32. However, the face of the sound absorber 30 may also protrude beyond the area bordering the resonator chamber 40, or only make up part of the bordering area. Towards the resonator chamber 40, the sound absorber 30 is covered by an acoustically reflecting inner wall 42 of the resonator chamber with a wall aperture 44.

(7) FIG. 2 shows a sectional side view of a device for reducing airborne and structure-borne sound 10′ according to the invention. The device comprises a flow channel 20′ which, starting from its longitudinal center line 201′, is bounded in radial direction by a flow channel wall 22′. The flow channel 20′ has an inlet 24′ and an outlet 26′ through which sound waves can enter and exit the flow channel 20′. A resonator chamber 40′ which is adjacent to the flow channel wall 22′ is arranged between the inlet 24′ and the outlet 26′. The flow channel wall 22′ is formed in the area bordering the resonator chamber 40′ from a sound absorber 30′ provided with openings 32′. Towards the resonator chamber 40′, the sound absorber 30′ is covered by an acoustically reflecting inner wall 42′ of the resonator chamber, which comprises a wall aperture 44′. In the embodiment example shown, the inner wall 42′ of the resonator chamber only has one wall aperture 44′. However, it may also have multiple wall apertures 44′. Furthermore, in the embodiment example of FIG. 1, the face of the sound absorber 30′ in the area bordering the resonator chamber 40′ is larger than the face of the wall aperture 44′. However, it may be sufficient if both faces are approximately the same size. Preferably, the face of the sound absorber 30′ in the area bordering the resonator chamber 40′ is at least twice as large as the face of the wall aperture 44′. It may also be three times as large as the face of the wall aperture 44′ or even larger still. Preferably, the sound absorber 30′ is formed from a foam that is roughened on its surface. For a particularly good reduction of turbulent flow, the sound absorber 30′ may be covered with a fleece (not shown here) towards the flow channel 20′. Furthermore, the resonator chamber may have one or more guide webs (not shown here).

(8) FIG. 3 shows a further embodiment of a device for reducing airborne and structure-borne sound 10″ according to the invention, in which four resonator chambers 40″ are arranged in series one behind the other in the flow direction of the sound waves between an inlet 24″ and an outlet 26″ of a flow channel 20″. The volumes of the resonator chambers 40″ are separated by end walls 46″. The resonator chambers 40″ may have guide webs 50″ which start from the outer wall 48″ of the resonator chamber facing away from the flow channel 20″, are spaced apart from the inner wall 42″ of the resonator chamber and run parallel to the end walls 46″ of the resonator chambers 40″. According to the embodiment example in FIG. 3, the individual resonator chambers 40″ have guide webs 50″ of different lengths. However, the guide webs 50″ may also be of the same length. As can be seen in FIG. 4, which shows a view of the embodiment of FIG. 3 cut along line IV-IV, the resonator chambers 40″ have a rectangular cross-section transverse to the longitudinal direction 101″ of the device for reducing airborne and structure-borne sound 10″. The outer wall of the resonator chamber 48″ runs parallel to the longitudinal direction 101″, while in the embodiment example of FIGS. 3 and 4 the flow channel wall 22″ is formed concavely in its longitudinal direction at least in the area bordering the resonator chamber 40″ and forms an open channel.

(9) Of course, the embodiments discussed in the special description and shown in the Figures are only illustrative embodiment examples of the present invention. This disclosure provides the person skilled in the art with a wide range of possible variations.