Three-section wide-frequency-domain engineering vehicle air conditioner noise reduction system

Abstract

The invention discloses a three-section wide-frequency-domain engineering vehicle air conditioner noise reduction system. The system comprises a first noise reduction section, a second noise reduction section and a third noise reduction section which are tubular and coaxial and are sequentially arranged in the airflow direction. The cross sectional area of the second noise reduction section is larger than that of the first noise reduction section, and the cross sectional area of the third noise reduction section is larger than that of the second noise reduction section. A plurality of sound absorption modules with Helmholtz resonant cavity structures are arranged on the pipe wall of the first noise reduction section; a splitter plate and a hollow perforated partition plate are arranged in the second noise reduction section, a cavity is formed in the hollow perforated partition plate, and the cavity communicates with noise reduction holes formed in one face of the hollow perforated partition plate; the air outlet of the third noise reduction section is provided with bionic flow guide fan blades used for inhibiting generation and falling of vortexes; multiple noise reduction mechanisms are integrated through the wing-shaped structure, and the wide-frequency-domain and multi-level noise reduction function of the engineering vehicle air conditioner is achieved.

Description

Technical Field

[0001] This invention belongs to the field of noise reduction technology for air conditioning systems of engineering vehicles, and particularly relates to a three-segment wideband noise reduction system for air conditioning systems of engineering vehicles. Background Technology

[0002] Air conditioning systems are an essential component of modern engineering vehicles, creating a comfortable driving environment for passengers. However, when the air conditioning is running, the high-speed airflow passing through the vents generates significant "wind noise." This noise not only reduces driving comfort but can also cause driver fatigue over time, affecting driving safety. Furthermore, engineering vehicles often operate in harsh conditions with high vibration and high dust levels. The high-powered diesel engines, hydraulic systems, and other equipment they are equipped with generate low-frequency noise and mid-to-high-frequency airflow noise, which can be transmitted into the cab through the air conditioning system, further deteriorating the driving environment.

[0003] In recent years, the application of silencing structures in the noise reduction systems of engineering vehicle air conditioning systems has become a common passive noise reduction method, but its performance still has significant shortcomings. For example, porous sound-absorbing materials such as lightweight sound-absorbing cotton and aluminum fiber sound-absorbing panels are pasted inside the air duct, relying on the internal pores of the material to dissipate sound energy. However, these materials are prone to pore blockage under long-term high dust and high humidity conditions, leading to a significant decrease in noise reduction performance and making it difficult to maintain effectiveness for a long time. Another example is the installation of airflow guiding structures such as wind deflectors and guide vanes inside the air duct, or the arrangement of resistive structures such as low-frequency resonance silencing cavities and expansion chamber silencing cavities. While the former can improve airflow organization and suppress some eddies, its absorption effect on mid-to-low frequency noise is limited, and the latter mainly targets specific frequency band noise, making it difficult to cover broadband noise. Furthermore, while airflow guiding structures designed based on biomimetic principles can effectively suppress eddy current shedding and reduce high-frequency aerodynamic noise, their attenuation capability for mid-to-low frequency noise is weak. Overall, existing methods often focus only on a single noise reduction mechanism and fail to organically combine broadband attenuation, resonant absorption and biomimetic flow guidance and vortex suppression. Therefore, it is difficult to achieve continuous, comprehensive and efficient noise reduction under the complex and ever-changing working conditions of engineering vehicles. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a three-segment wideband noise reduction system for engineering vehicle air conditioning that can achieve multi-band noise attenuation.

[0005] Technical Solution: The three-section wideband engineering vehicle air conditioning noise reduction system of the present invention includes a tubular coaxial first noise reduction section, a second noise reduction section, and a third noise reduction section arranged sequentially along the airflow direction; the cross-sectional area of ​​the second noise reduction section is larger than that of the first noise reduction section, and the cross-sectional area of ​​the third noise reduction section is larger than that of the second noise reduction section; the first noise reduction section and the second noise reduction section are connected by a first expansion chamber, and the second noise reduction section and the third noise reduction section are connected by a second expansion chamber; the first noise reduction section has a plurality of sound-absorbing modules with Helmholtz resonant cavity structures on its pipe wall; the second noise reduction section has a flow divider plate and a hollow perforated baffle plate inside, the hollow perforated baffle plate has a cavity, and the cavity communicates with a sound-absorbing hole on one side of the hollow perforated baffle plate; the air outlet of the third noise reduction section is provided with biomimetic guide fan blades for suppressing the generation and shedding of vortices.

[0006] Furthermore, both the first expansion chamber and the second expansion chamber have abrupt changes in cross-section; the ratio of the cross-sectional area of ​​the first noise reduction section to the cross-sectional area of ​​the second noise reduction section is 1:4; and the ratio of the cross-sectional area of ​​the second noise reduction section to the cross-sectional area of ​​the third noise reduction section is 1:4.

[0007] Furthermore, the sound-absorbing module contains several interconnected chambers, each chamber being a cube with a side length of 13 mm; each pair of adjacent chambers is connected by a chamber connection hole; and the cross-sectional shape, cross-sectional dimensions, and / or axial length of different chamber connection holes are not exactly the same; the diameter of the chamber connection hole is 1 mm to 2 mm, and the length is 11 mm to 26 mm; the outer wall thickness of the sound-absorbing module is 1 mm.

[0008] Furthermore, the sound-absorbing modules are distributed uniformly or non-uniformly in the axial and circumferential directions of the first noise reduction section.

[0009] Furthermore, the sound-absorbing module is connected to the main air duct of the first noise reduction section through a connection hole.

[0010] Furthermore, the splitter plate has a right-angled structure, with the right-angle vertex of the splitter plate located at the axis of the second noise reduction section, and the side of the splitter plate forming a 45° angle with the axis.

[0011] Furthermore, the hollow perforated partition is wavy, and the sound-absorbing holes on the hollow perforated partition are evenly or unevenly distributed.

[0012] Furthermore, the hollow perforated partition is axially distributed along the second noise reduction section.

[0013] Furthermore, the hollow perforated partition near the channel wall has the side with the sound-absorbing holes facing the inner wall of the second noise reduction section.

[0014] Furthermore, the biomimetic guide fan blades are evenly distributed at the air outlet of the third noise reduction section, and the biomimetic guide fan blades are axially inclined relative to the third noise reduction section; a semi-elliptical biomimetic guide protrusion is distributed on one side surface of the biomimetic guide fan blade; the height of the biomimetic guide protrusion is 1mm to 2mm, the width is 1mm to 1.5mm, and the spacing between adjacent biomimetic guide protrusions is 10mm to 15mm.

[0015] Beneficial effects: Compared with the prior art, the present invention forms a multi-band noise suppression covering low, mid and high frequencies by integrating the four mechanisms of Helmholtz resonant cavity, expansion chamber resistive noise reduction, porous plate / labyrinth resistive noise reduction and biomimetic flow guiding vortex reduction. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the sound-absorbing module structure of the Helmholtz resonant cavity structure according to an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of a hollow perforated partition structure according to an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of the biomimetic guide fan blade structure according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0021] like Figure 1 As shown, the three-section wideband engineering vehicle air conditioning noise reduction system described in this embodiment includes a tubular coaxial first noise reduction section 1, a second noise reduction section 3, and a third noise reduction section 6 arranged sequentially along the airflow direction; the cross-sectional area of ​​the second noise reduction section 3 is larger than that of the first noise reduction section 1, and the cross-sectional area of ​​the third noise reduction section 6 is larger than that of the second noise reduction section 3; the first noise reduction section 1 and the second noise reduction section 3 are connected by a first expansion chamber 9, and the second noise reduction section 3 and the third noise reduction section 6 are connected by a second expansion chamber 5; the first noise reduction section 1 has a plurality of sound-absorbing modules 2 with Helmholtz resonant cavity structures on its pipe wall; the second noise reduction section 3 has a flow divider 8 and a hollow perforated partition 4 inside, the hollow perforated partition 4 has a cavity 14, and the cavity 14 communicates with a sound-absorbing hole 13 on one side of the hollow perforated partition 4; the air outlet of the third noise reduction section 6 is provided with biomimetic guide fan blades 7 for suppressing the generation and shedding of vortices.

[0022] The first noise reduction section 1 forms the initial airflow channel, possessing the smallest possible cross-sectional area. Multiple sound-absorbing modules 2 are evenly distributed along the axial and circumferential directions on the pipe wall of this section, such as... Figure 2 As shown, it is specifically designed to absorb low-to-mid frequency noise; each sound-absorbing module 2 is a multi-cavity series structure based on the Helmholtz resonance principle, which is connected to the main air duct through the chamber 10 and the connecting hole 12. The module contains multiple chambers 10, and adjacent chambers 10 are connected in series through the chamber connecting hole 11.

[0023] Preferably, the shapes, cross-sectional areas and lengths of the connecting holes 11 of different chambers do not completely overlap, so that each chamber 10 has a different resonant frequency, allowing a single sound-absorbing module 2 to cover a wider low-frequency band, while the combination of multiple sound-absorbing modules 2 further broadens the sound absorption band for mid-low frequency noise.

[0024] Preferably, the cross-section of the first noise reduction segment 1 is a square with a length of 80mm.

[0025] Preferably, the sound-absorbing module 2 is distributed in the circumferential and axial directions of the first noise reduction section 1.

[0026] Optionally, the sound-absorbing modules 2 are distributed uniformly or non-uniformly along the circumferential and axial directions.

[0027] Optionally, the two connecting holes (connecting hole 12 and chamber connecting hole 11) of the first chamber (the chamber connected to the main channel) of the sound-absorbing module 2 are axially perpendicular or intersecting in three dimensions.

[0028] Preferably, the noise frequencies covered by the chamber 10 are not all the same.

[0029] Preferably, the noise frequency range covered by the sound-absorbing module 2 is not entirely the same.

[0030] Optionally, the cross-sectional shape of the connecting hole 12 is circular or polygonal.

[0031] Preferably, the perforated surface of the sound-absorbing module 2 is on the same horizontal plane as the flow channel surface of the first noise reduction section 1.

[0032] Preferably, the wall thickness of the sound-absorbing module 2 is 1 mm.

[0033] Preferably, the diameter of the chamber connection hole 11 is 1 mm to 2 mm and the length is 11 mm to 26 mm, and the chamber 101 is a cube with a side length of 13 mm.

[0034] Preferably, the sound-absorbing modules 2 are spaced 135mm apart along the axial direction of the first noise reduction section 1, and the number of them distributed axially is 4-12.

[0035] Preferably, the noise reduction frequency band of the noise reduction module 2 is 300-1200Hz.

[0036] Preferably, the outlet of the first noise reduction section 1 is connected to the first expansion chamber 9. The flow cross-section of the first expansion chamber 9 is significantly larger than that of the first noise reduction section 1, forming the first abrupt change in cross-section. This structure utilizes the principle of acoustic impedance mismatch to cause some of the mid-frequency sound waves propagating there to be reflected and interfere with each other, thereby achieving the first reactive noise cancellation.

[0037] After passing through the first expansion chamber 9, the airflow enters the second noise reduction section 3, which has a medium cross-sectional area. A flow divider 8 is provided in the second noise reduction section 3, which initially divides the oncoming airflow into two streams, upper and lower.

[0038] Preferably, the cross-sectional shape of the second noise reduction segment 3 is a square with a length of 160mm.

[0039] Preferably, the ratio of the cross-sectional area of ​​the first noise reduction segment 1 to the cross-sectional area of ​​the second noise reduction segment 3 is 1:4; and the ratio of the cross-sectional area of ​​the second noise reduction segment 3 to the cross-sectional area of ​​the third noise reduction segment 6 is 1:4.

[0040] Preferably, the diverter plate 8 is a raised flat plate structure with an angle of 90° between the two plates and a thickness of 2mm.

[0041] Preferably, the distance between the diverter plate and the front end of the second noise reduction section 3 is 15mm, and its upper surface is at a 45° angle to the central symmetry plane of the first expansion chamber 9.

[0042] The core noise reduction component of the second noise reduction stage 3 is a number of hollow perforated partitions 4.

[0043] Preferably, the hollow perforated partitions 4 are spaced 30mm apart.

[0044] The interior is a cavity 14. Hollow perforated baffles 4 are located at the top and bottom of the flow channel, with their perforated surfaces close to the inner wall of the second noise reduction section 3 to optimize the sound absorption effect of the boundary layer.

[0045] Preferred, such as Figure 3 As shown, the hollow perforated baffle 4 is preferably made in a wave shape, and a large number of sound-absorbing holes 13 are uniformly opened on its surface. Multiple hollow perforated baffles 4 are arranged at intervals along the direction of airflow in the second noise reduction section 3, forming a tortuous flow channel and sound wave reflection path. When the airflow carrying noise passes through this area, the sound waves are forced to reflect multiple times in the tortuous path formed by the baffles 4, and continuously enter and exit the cavity 14 through the sound-absorbing holes 13, generating friction and dissipation. This process prolongs the propagation path of the sound waves, converting mid-to-high frequency sound energy into heat energy.

[0046] Preferably, the hollow perforated baffles 4 located at the top and bottom of the flow channel of the second noise reduction section 3 have their perforated surfaces close to the inner wall of the second noise reduction section 3 to optimize the sound absorption effect of the boundary layer. The flow divider 8 is embedded in the array of hollow perforated baffles 4.

[0047] Preferably, the hollow perforated partition is a thin-walled structure with an internal cavity thickness of 1 mm and a wall thickness of 0.5 mm.

[0048] Optionally, apart from the orientation of the perforated surface of the hollow perforated baffle 4 located at the top and bottom of the flow channel of the second noise reduction section 3, the other orientation combinations of the hollow perforated baffle 4 include a variety of combinations.

[0049] Optionally, the number of the hollow perforated partitions 4 may vary.

[0050] Optionally, the shape, size, spacing, and number of sound-absorbing holes on the surface of the hollow perforated partition 4 can be varied.

[0051] Preferably, the noise reduction frequency band of the hollow perforated partition 4 is the mid-to-high frequency band above 1200Hz.

[0052] Preferably, the second noise reduction section 3 and the third noise reduction section 6 are connected by a second expansion chamber 5. The third noise reduction section 6 has the largest cross-sectional area and a biomimetic guide fan blade 7 at the air outlet.

[0053] Preferably, the cross-section of the third noise reduction segment 6 is a square with a size of 320mm.

[0054] Furthermore, the structure of the biomimetic guide fan blade 7 mimics the protrusions at the tip of an owl's feathers. As air exits from the outlet, these biomimetic protrusions can suppress the generation and shedding of vortices (which generate noise), reducing noise generation at its source.

[0055] Preferably, the spacing between the biomimetic guide fan blades 7 is 15mm.

[0056] Preferably, the biomimetic guide fan blades 7 are evenly distributed at the air outlet.

[0057] Preferably, the biomimetic guide fan blade 7 is placed at an angle at the air outlet.

[0058] Preferred, such as Figure 4 As shown, the biomimetic guide fan blade 7 is provided with a semi-elliptical biomimetic guide protrusion 15.

[0059] Preferably, the biomimetic flow guiding protrusion 15 has a height of 1mm to 2mm, a width of 1mm to 1.5mm, and a spacing of 10mm to 15mm between adjacent biomimetic flow guiding protrusions 15.

Claims

1. A three-segment wideband engineering vehicle air conditioning noise reduction system, characterized in that, It includes a tubular, coaxial noise reduction section (1), a second noise reduction section (3), and a third noise reduction section (6) arranged sequentially along the airflow direction; the cross-sectional area of ​​the second noise reduction section (3) is larger than that of the first noise reduction section (1), and the cross-sectional area of ​​the third noise reduction section (6) is larger than that of the second noise reduction section (3); the first noise reduction section (1) and the second noise reduction section (3) are connected by a first expansion chamber (9), and the second noise reduction section (3) and the third noise reduction section (6) are connected by a second expansion chamber (5). The first noise reduction section (1) has several sound-absorbing modules (2) with Helmholtz resonant cavity structures on its pipe wall; the second noise reduction section (3) has a flow divider (8) and a hollow perforated partition (4) inside, and the hollow perforated partition (4) has a cavity (14) in it, and the cavity (14) is connected to a sound-absorbing hole (13) on one side of the hollow perforated partition (4); the third noise reduction section (6) has a biomimetic guide fan blade (7) at its air outlet to suppress the generation and shedding of vortices.

2. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The first expansion chamber (9) and the second expansion chamber (5) are both cross-sectional abrupt structures; the ratio of the cross-sectional area of ​​the first noise reduction section (1) and the second noise reduction section (3) is 1:4; the ratio of the cross-sectional area of ​​the second noise reduction section (3) and the third noise reduction section (6) is 1:

4.

3. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The sound-absorbing module (2) contains several interconnected chambers (10), each chamber (10) being a cube with a side length of 13 mm. Each pair of adjacent chambers (10) are connected by a chamber connection hole (11). The cross-sectional shape, cross-sectional dimensions, and / or axial length of different chamber connection holes (11) are not exactly the same. The diameter of the chamber connection hole (11) is 1 mm to 2 mm, and the length is 11 mm to 26 mm. The outer wall thickness of the sound-absorbing module (2) is 1 mm.

4. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The sound-absorbing modules (2) are distributed uniformly or non-uniformly in the axial and circumferential directions of the first noise reduction section (1).

5. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The sound-absorbing module (2) is connected to the main air duct of the first noise reduction section (1) through the connection hole (12).

6. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The diverter plate (8) is a right-angled structure. The right-angle vertex of the diverter plate (8) is located at the axis of the second noise reduction section (3), and the side of the diverter plate (8) forms an angle of 45° with the axis.

7. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The hollow perforated partition (4) is wavy, and the sound-absorbing holes (13) on the hollow perforated partition (4) are evenly or unevenly distributed.

8. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The hollow perforated partition (4) is axially distributed along the second noise reduction section (3).

9. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The hollow perforated partition (4) near the channel wall has the side with the sound-absorbing hole (13) facing the inner wall of the second noise reduction section (3).

10. The three-segment wideband engineering vehicle air conditioning noise reduction system according to claim 1, characterized in that, The bionic guide fan blades (7) are evenly distributed at the air outlet of the third noise reduction section (6), and the bionic guide fan blades (7) are axially inclined relative to the third noise reduction section (6); a semi-elliptical bionic guide protrusion (15) is distributed on one side surface of the bionic guide fan blades (7); the height of the bionic guide protrusion (15) is 1mm to 2mm, the width is 1mm to 1.5mm, and the distance between adjacent bionic guide protrusions (15) is 10mm to 15mm.

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