Muffler

Abstract

The present invention discloses a muffler, which comprises: a waveguide provided with a sound wave inlet; a first resonance cavity and a second resonance cavity arranged along the tube length direction of the waveguide, the first resonance cavity being arranged closer to the sound wave inlet of the waveguide than the second resonance cavity, and the first resonance cavity and the second resonance cavity being Helmholtz resonance cavities; a first neck tube communicating with the waveguide is provided on the first resonance cavity, a second neck tube communicating with the waveguide is provided on the second resonance cavity, and the cross-sectional area of the second neck tube is larger than that of the first neck tube. By arranging two Helmholtz resonance cavities with different cross-sectional areas of the neck tubes on the waveguide, the present invention has a relatively high prediction accuracy of the noise reduction effect. Secondly, the first neck tube and the second neck tube adopt a bent tube design, which can not only ensure a more compact structure, but also is beneficial to low-frequency noise reduction and miniaturization design.

Description

Technical Field

[0001] The present invention relates to the technical field of silencing devices, and more particularly to a muffler. Background Art

[0002] In the existing noise reduction technologies, the traditional method is to stick porous materials such as sound-absorbing cotton on the wall surface of the ventilation duct. If the ventilation and heat dissipation performance is to be ensured, the thickness of the sound-absorbing cotton is limited, resulting in limited noise reduction ability. In addition, designing acoustic metamaterials near the air inlets and outlets of the ventilation system can achieve a noise reduction effect of 1 - 3 dB. However, for different application scenarios, if the acoustic boundary is relatively complex, it is impossible to perform forward design through simulation, and it is difficult to grasp the target noise reduction frequency band; the noise reduction amplitude will also fluctuate with the change of the size of the ventilation opening. In the existing noise reduction technologies, designing resonance cavities on the side walls of the waveguide has been widely used, and its noise reduction effect is generally measured by transmission loss, which consists of two parts: reflection and absorption.

[0003] In the traditional method, a Helmholtz resonance cavity is designed for one frequency point. Although the transmission loss can be increased by thickening the neck tube, the upper limit of the sound energy consumed by absorption is 50%, and the remaining part of the transmission loss is contributed by reflection. The reflected sound waves may radiate outward from other positions, which is not conducive to noise reduction; at the same time, in the traditional Helmholtz resonance cavity, the neck tube is located outside the back cavity, and the height of the resonance cavity is equal to the sum of the length of the neck tube and the height of the back cavity, resulting in a large volume and low space utilization rate. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, an object of the present invention is to provide a muffler to solve the problems of poor noise reduction effect and large volume of the muffler in the related art.

[0005] The muffler according to an embodiment of the present invention includes: a waveguide provided with a sound wave inlet; a first resonance cavity and a second resonance cavity arranged along the tube length direction of the waveguide, the first resonance cavity being arranged closer to the sound wave inlet of the waveguide than the second resonance cavity, and the first resonance cavity and the second resonance cavity being Helmholtz resonance cavities; a first neck tube communicating with the waveguide is provided on the first resonance cavity, a second neck tube communicating with the waveguide is provided on the second resonance cavity, the cross-sectional area of the second neck tube is larger than that of the first neck tube, and both the first neck tube and the second neck tube are bent tubes.

[0006] The muffler according to the embodiment of the present invention is provided with a first resonance cavity and a second resonance cavity with different cross-sectional areas of the neck tube on the waveguide. While ensuring good ventilation and heat dissipation, it can bring relatively good noise reduction effect. The acoustic boundary in the waveguide remains unchanged (simple and stable), and the prediction accuracy of the noise reduction effect is relatively high, which is beneficial to the positive design of noise reduction. Moreover, by designing two Helmholtz resonance cavities at the same frequency point, a transmission loss higher than 10 dB at the target frequency can be achieved, and sound absorption plays a major role, with the sound absorption coefficient above 0.9. Secondly, the first neck tube and the second neck tube adopt a bent tube design, which can not only ensure a more compact structure but also is beneficial to low-frequency noise reduction and miniaturization design.

[0007] In some embodiments of the present invention, a first cavity is formed inside the first resonance cavity, and the first neck tube is arranged inside the first cavity; a second cavity is formed inside the second resonance cavity, and the second neck tube is arranged inside the second cavity.

[0008] In some embodiments of the present invention, the bent tube includes at least two tube portions, at least two of the tube portions are connected in sequence, and an included angle is formed between any two adjacent tube portions, and the included angle is 0 to 90 degrees.

[0009] In some embodiments of the present invention, any two adjacent tube portions are connected by a right-angle transition or an arc transition.

[0010] In some embodiments of the present invention, the cross-sectional area of the first neck tube and the cross-sectional area of the second neck tube are 0.3% to 20% of the cross-sectional area of the waveguide.

[0011] In some embodiments of the present invention, the distance between the first neck tube and the second neck tube is 50 mm to 300 mm.

[0012] In some embodiments of the present invention, the cross-sectional profiles of the first resonance cavity and the second resonance cavity are rectangular.

[0013] In some embodiments of the present invention, the first neck tube is eccentrically arranged on the first resonance cavity and is located on the side away from the second resonance cavity, and the second neck tube is eccentrically arranged on the second resonance cavity and is located on the side away from the first resonance cavity.

[0014] In some embodiments of the present invention, the cross-sectional profiles of the first neck tube and the second neck tube are circular or square.

[0015] In some embodiments of the present invention, the first resonance cavity and the second resonance cavity are arranged in multiple groups along the tube length direction of the waveguide, and each group includes a first resonance cavity and a second resonance cavity.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned by practice of the present invention. Brief Description of the Drawings

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is an internal cross-sectional view of a muffler in an embodiment of the present invention;

[0019] Figure 2 is an internal cross-sectional view of the first resonance cavity of the muffler in an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of an eccentric structure of the resonance cavity of the muffler in an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of an internal insertion tube type of the resonance cavity of the muffler in an embodiment of the present invention.

[0022] Reference Signs:

[0023] 100, muffler;

[0024] 10, waveguide;

[0025] 20, first resonance cavity; 201, first neck tube; 202, first cavity;

[0026] 30, second resonance cavity; 301, second neck tube; 302, second cavity; 1011, tube portion. Detailed Description of the Embodiments

[0027] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0028] Reference will be made below to Figures 1 - 4 , to describe a muffler 100 according to an embodiment of the present invention. The muffler 100 can be applied to a variety of devices that require noise reduction, for example, the muffler 100 can be applied to an air duct machine. The muffler 100 is connected to the air outlet of the air duct machine to achieve noise reduction of the air duct machine. For another example, the muffler 100 can also be applied to the compressor compartment of a refrigerator to eliminate the noise generated by the compressor. Of course, only examples are given here, and the muffler 100 can also be applied to other devices that require noise reduction, which will not be elaborated here.

[0029] As Figures 1 to 4 shown, the muffler 100 according to an embodiment of the present invention includes: a waveguide 10, a first resonance cavity 20, and a second resonance cavity 30.

[0030] An acoustic wave inlet (not shown in the figure) is provided on the waveguide 10; the first resonance cavity 20 and the second resonance cavity 30 are arranged along the tube length direction of the waveguide 10, the first resonance cavity 20 is arranged closer to the acoustic wave inlet of the waveguide 10 than the second resonance cavity 30, and the first resonance cavity 20 and the second resonance cavity 30 are Helmholtz resonance cavities; a first neck tube 201 communicating with the waveguide 10 is provided on the first resonance cavity 20, a second neck tube 301 communicating with the waveguide 10 is provided on the second resonance cavity 30, the cross-sectional area of the second neck tube 301 is larger than the cross-sectional area of the first neck tube 201, and both the first neck tube 201 and the second neck tube 301 are bent tubes.

[0031] It can be understood that the waveguide 10 can play a role in ventilation and heat dissipation, and can control the sound propagation path, and cooperate with the first resonance cavity 20 and the second resonance cavity 30 to play a noise reduction role. The cross-sectional area of the first neck tube 201 of the first resonance cavity 20 is relatively small, its reflection coefficient is relatively low, and its sound absorption coefficient is relatively high, mainly playing a sound absorption role, and the sound absorption effect is relatively good. The cross-sectional area of the second neck tube 301 of the second resonance cavity 30 is relatively large, its reflection coefficient is relatively high, and its sound absorption coefficient is relatively low, mainly playing a reflection role, and the effect of reflecting acoustic waves is relatively good. The acoustic wave enters from the waveguide 10, first passes through the first resonance cavity 20, and then passes through the second resonance cavity 30 and radiates outward. Through the combined action of the first resonance cavity 20 and the second resonance cavity 30, the peak value of the sound absorption coefficient can be increased to 0.9474, which is equivalent to a noise reduction of 12.8 dB, and the transmittance is as low as 0.0028. The transmission loss is mainly contributed by sound absorption, and more than 94% of the sound energy is converted into heat energy through friction in the resonance cavity.

[0032] Secondly, both the first neck tube 201 of the first resonance cavity 20 and the second neck tube 301 of the second resonance cavity 30 are bent tubes. Adopting this method can extend the tube lengths of the first neck tube 20 and the second neck tube 301, and ensure that their structures are relatively compact, so that the first-order resonance frequency of the resonance cavity is greatly reduced, which is suitable for low-frequency noise reduction.

[0033] The muffler 100 according to the embodiments of the present invention is provided with a first resonance cavity 20 and a second resonance cavity 30 with different cross-sectional areas of the neck tube on the waveguide 10. While ensuring good ventilation and heat dissipation, it can bring a relatively good noise reduction effect. The acoustic boundary in the waveguide 10 remains unchanged, and the prediction accuracy of the noise reduction effect is relatively high. Moreover, by designing two Helmholtz resonance cavities at the same frequency point, a transmission loss higher than 10 dB at the target frequency can be achieved, and sound absorption plays a major role, with the sound absorption coefficient being above 0.9. Secondly, the first neck tube 201 and the second neck tube 301 adopt a bent tube design, which can not only ensure a more compact structure but also is beneficial to low-frequency noise reduction and miniaturization design.

[0034] As Figure 1 , Figure 2 , Figure 4 shown, in some embodiments of the present invention, a first cavity 202 is formed inside the first resonance cavity 20, and the first neck tube 201 is arranged in the first cavity 202; a second cavity 202 is formed inside the second resonance cavity 20, and the second neck tube 201 is arranged in the second cavity 202.

[0035] Specifically, the first neck tube 201 and the second neck tube 301 are respectively arranged in the first cavity 202 and the second cavity 302, so that the first neck tube 201 constitutes an inner insertion tube design on the first resonance cavity 20, and the second neck tube 301 constitutes an inner insertion tube design on the second resonance cavity 20. This reduces the back cavity height of the two Helmholtz resonance cavities, shrinks the volume of the muffler 100, makes its structure more compact, and makes the application range of the muffler 100 wider; at the same time, arranging the first neck tube 201 and the second neck tube 301 in the first cavity 202 and the second cavity 302 respectively also improves the space utilization rate of the muffler 100.

[0036] As Figure 1 , Figure 2 In some embodiments of the present invention, both the first neck tube 201 and the second neck tube 301 are bent tubes. The bent tube includes at least two tube portions 1011, and the at least two tube portions 1011 are connected in sequence. An angle is formed between any two adjacent tube portions 1011, and the angle is 0 to 90 degrees. That is to say, the angle formed between any two tube portions 201 can be any value among 0 degrees, 10 degrees, 30 degrees, 45 degrees, 60 degrees, 80 degrees, and 90 degrees. For example, when α is 0 degrees, two adjacent tube portions 1011 are arranged parallel to each other. Of course, the angle α is not limited to the above examples and can also be other values within the range of 0 to 90 degrees, which can be specifically set according to the situation.

[0037] In some embodiments of the present invention, any two adjacent tube portions 1011 are connected by a right-angle transition or an arc transition. That is to say, the bent part of the two tube portions 1011 can be a right angle or an arc, with the final actual situation as the design reference.

[0038] In some embodiments of the present invention, the cross-sectional area of the first neck tube 201 and the cross-sectional area of the second neck tube 301 are 0.3% to 20% of the cross-sectional area of the waveguide 10.

[0039] It can be understood that for a wavelength tube 10 of a certain area, as the cross-sectional area of the neck tube of the Helmholtz resonance cavity increases, the sound absorption coefficient first increases and then decreases, with a maximum value of 0.5, the reflection coefficient continuously increases, and the transmission loss continuously increases; therefore, the first neck tube 201 of the first resonance cavity 20 should be the pipe diameter size when the sound absorption coefficient is close to 0.5, and the second neck tube 301 of the second resonance cavity 30 should be the pipe diameter size when the transmittance of the Helmholtz resonance cavity is relatively low and the reflectance is relatively high. At this time, the first resonance cavity 20 and the second resonance cavity 30 cooperate to have the best noise reduction ability; the optimal pipe diameter range for both is that the cross-sectional areas of the first neck tube 201 and the second neck tube 301 are 0.3% to 20% of the cross-sectional area of the waveguide 10. The cross-sectional areas of the first neck tube 201 and the second neck tube 301 can be any value among 0.3%, 0.5%, 1%, 2%, 4%, 8%, 10%, 15%, 20% of the cross-sectional area of the waveguide 10. Of course, they can also be other values within the range, which will not be elaborated here one by one. The final value shall be subject to the design requirements of the waveguide pipe diameter.

[0040] As Figure 1 、 Figure 3 shown, in some embodiments of the present invention, the distance between the first neck tube 201 and the second neck tube 301 is 50 mm to 300 mm.

[0041] Specifically, the distance between the first neck tube 201 and the second neck tube 301 within the range of 50 mm to 300 mm does not affect the sound frequency band targeted for noise reduction; if the distance between the first neck tube 201 and the second neck tube 301 exceeds the range, sound will transmit out of the wavelength tube 10, weakening the noise reduction effect of the muffler 100; another important function of the distance range between the first neck tube 201 and the second neck tube 301 is to provide installation space for the first resonance cavity 20 and the second resonance cavity 30, improving space utilization. For example, the distance d1 between the first neck tube 201 and the second neck tube 301 can be any value among 50 mm, 80 mm, 100 mm, 150 mm, 180 mm, 200 mm, 250 mm, 280 mm, 300 mm. Of course, it can also be other values within the range of 50 mm to 300 mm, which will not be elaborated here one by one.

[0042] As Figure 1 、 Figure 2As shown, in some embodiments of the present invention, the cross-sectional profiles of the first resonance cavity 20 and the second resonance cavity 30 are rectangular. Specifically, the cross-sectional shapes of the first resonance cavity 20 and the second resonance cavity 30 do not affect the noise reduction ability of the muffler 100. Therefore, different cross-sectional designs provide more possibilities for the appearance design of the muffler 100. Thus, the cross-sectional profiles of the waveguide 10, the first resonance cavity 20, and the second resonance cavity 30 can be configured as a square or a rectangle. To maximize the use of space, the cross-sectional profiles of the waveguide 10, the first resonance cavity 20, and the second resonance cavity 30 of the device 100 are designed as squares.

[0043] As Figure 3 shown, in some embodiments of the present invention, the first neck tube 201 is eccentrically arranged on the first resonance cavity 20 and is located on the side away from the second resonance cavity 30, and the second neck tube 301 is eccentrically arranged on the second resonance cavity 30 and is located on the side away from the first resonance cavity 20. The eccentric design of the first neck tube 201 and the second neck tube 301 shortens the total length of the muffler 100 without changing the distance between the first resonance cavity 20 and the second resonance cavity 30, which is beneficial to the miniaturization design of the muffler 100, enabling the muffler 100 to be applicable to more spatial structures and being more flexible and convenient to use.

[0044] In some embodiments of the present invention, the cross-sectional profiles of the first neck tube 201 and the second neck tube 301 are circular or square. Specifically, the cross-sectional profile shapes of the first neck tube 201 and the second neck tube 301 do not affect the noise reduction effect of the muffler 100. For example, if the cross-sectional profiles of the first neck tube 201 and the second neck tube 301 are circular, their cross-sectional profiles can also be square, rectangular, or of course other regular shapes, which will not be elaborated here one by one.

[0045] In some embodiments of the present invention, the first resonance cavity 20 and the second resonance cavity 30 are arranged in multiple groups along the tube length direction of the waveguide 10, and each group includes a first resonance cavity 20 and a second resonance cavity 30.

[0046] That is to say, since the first resonance cavity 20 and the second resonance cavity 30 are composed of Helmholtz resonance cavities, the Helmholtz resonance cavities have extremely high sound absorption coefficients and extremely low transmittance, and can achieve the sound absorption and noise reduction effect targeted at a specific sound frequency band. The combination of multiple groups of the first resonance cavity 20 and the second resonance cavity 30 can achieve targeted noise reduction for multiple sound frequency bands within a range.

[0047] Next, a specific embodiment of the muffler 100 of the present invention will be described with reference to the accompanying drawings.

[0048] As Figures 1 - 3 shown, the muffler 100 includes: a waveguide 10, a first resonance cavity 20, and a second resonance cavity 30.

[0049] The waveguide 10 is used for the flow of air, ensuring the heat dissipation effect of the connected equipment.

[0050] The first resonance cavity 20 and the second resonance cavity 30 are arranged along the tube length direction of the waveguide 10 and communicate with the outer tube wall of the waveguide 10. The first resonance cavity 20 is arranged closer to the air inlet of the waveguide 10 relative to the second resonance cavity 30. Both the first resonance cavity 20 and the second resonance cavity 30 are Helmholtz resonance cavities. The cross-sectional area of the second neck tube 301 of the second resonance cavity 30 is larger than the cross-sectional area of the first neck tube 201 of the first resonance cavity 20.

[0051] The first neck tube 201 of the first resonance cavity 20 is inside the first cavity 202, and the second neck tube 301 of the second resonance cavity 30 is inside the second cavity 302.

[0052] Both the first neck tube 201 and the second neck tube 301 are bent tubes.

[0053] The first neck tube 201 is bent to form three tube parts 1011, and the second neck tube 301 is bent to form two tube parts 1011. The included angle formed between any two tube parts 1011 is 90 degrees.

[0054] The first neck tube 201 is eccentrically arranged on the first resonance cavity 20 and is on the side far from the second resonance cavity 30. The second neck tube 301 is eccentrically arranged on the second resonance cavity 30 and is on the side far from the first resonance cavity 20.

[0055] The distance between the first resonance cavity 20 and the second resonance cavity 30 is 50 mm.

[0056] The cross-sectional area of the first neck tube 201 is 0.3% of the cross-sectional area of the waveguide 10, and the cross-sectional area of the second neck tube 301 is 1.5% of the cross-sectional area of the waveguide 10.

[0057] The cross-sectional profiles of the waveguide 10, the first resonance cavity 20, the second resonance cavity 30, the first neck tube 201, and the second neck tube 301 are square.

[0058] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0059] In the description of this specification, the descriptions with reference to the terms "some embodiments", "optionally", "further", "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0060] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A muffler, characterized in that, Comprising: A waveguide, with a sound wave inlet provided on the waveguide; A first resonance cavity and a second resonance cavity, the first resonance cavity and the second resonance cavity are arranged along the tube length direction of the waveguide, the first resonance cavity is arranged closer to the sound wave inlet of the waveguide relative to the second resonance cavity, and the first resonance cavity and the second resonance cavity are Helmholtz resonance cavities; A first neck tube communicating with the waveguide is provided on the first resonance cavity, a second neck tube communicating with the waveguide is provided on the second resonance cavity, the cross-sectional area of the second neck tube is larger than the cross-sectional area of the first neck tube, and both the first neck tube and the second neck tube are bent tubes; A first cavity is formed inside the first resonance cavity, and the first neck tube is arranged inside the first cavity; a second cavity is formed inside the second resonance cavity, and the second neck tube is arranged inside the second cavity.

2. The muffler according to claim 1, characterized in that, The bent tube includes at least two tube portions, the at least two tube portions are connected in sequence, and an included angle is formed between any two adjacent tube portions, and the included angle is 0 to 90 degrees.

3. The muffler according to claim 2, characterized in that, Any two adjacent tube portions are connected by a right-angle transition or an arc transition.

4. The muffler according to claim 1, characterized in that, The cross-sectional area of the first neck tube and the cross-sectional area of the second neck tube are 0.3% to 20% of the cross-sectional area of the waveguide.

5. The muffler according to claim 1, characterized in that, The distance between the first neck tube and the second neck tube is 50 mm to 300 mm.

6. The muffler according to claim 1, characterized in that, The cross-sectional profiles of the first resonance cavity and the second resonance cavity are rectangular.

7. The muffler according to claim 1, characterized in that, The first neck tube is eccentrically arranged on the first resonance cavity and is located on the side away from the second resonance cavity, and the second neck tube is eccentrically arranged on the second resonance cavity and is located on the side away from the first resonance cavity.

8. The muffler according to claim 1, characterized in that, The cross-sectional profiles of the first neck tube and the second neck tube are circular or square.

9. The muffler according to claim 1, characterized in that, The first resonance cavity and the second resonance cavity are arranged in multiple groups along the tube length direction of the waveguide, and each group includes one first resonance cavity and one second resonance cavity.

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