Impedance silencer and working method thereof

Abstract

The invention discloses an impedance silencing device and a working method thereof.The device comprises a silencer barrel, an air inlet pipe and an air outlet pipe, the air inlet pipe and the air outlet pipe are located at the two ends of the silencer barrel, the impedance silencing device is characterized by further comprising a silencing assembly and a flow guide mechanism, the silencing assembly and the flow guide mechanism are arranged in the silencer barrel, the inner diameter of the air inlet pipe is gradually increased in the airflow direction, and the outer diameter of the air outlet pipe is gradually increased in the airflow direction. The inner diameter of the air outlet pipe is gradually reduced in the airflow direction, and the air inlet pipe, the silencer barrel and the air outlet pipe form an expansion chamber structure. The silencing assembly comprises silencing plates which are fixedly arranged in the silencer barrel and divide an inner cavity of the silencer into a plurality of silencing channels connected in parallel. The flow guide mechanism comprises a flow guide cone arranged on the air inlet pipe, the flow guide cone is connected with a control assembly used for controlling the flow guide cone to move in the axial direction of the silencer barrel, the problem that the silencing performance and operation energy consumption of a fixed silencer cannot be considered at the same time under the variable working conditions is solved, and self-adaptive broadband efficient silencing and energy-saving operation are achieved.

Description

Technical Field

[0001] This invention relates to the field of noise reduction equipment technology, and in particular to an impedance noise reduction device and its working method. Background Technology

[0002] Noise pollution has become one of the major environmental problems in industrial production, especially the pipeline noise generated by equipment such as fans and air compressors when transporting compressed air. This type of noise not only has a wide frequency range and high sound pressure level, but is also often accompanied by strong airflow pulsations, seriously endangering human health and reducing work efficiency. Therefore, developing efficient pipeline noise reduction devices is of great significance for improving the working environment and meeting environmental protection requirements.

[0003] To address the aforementioned issues, existing technologies commonly employ impedance composite silencers to reduce pipeline noise. These silencers typically consist of an outer cylinder, an inner sound-absorbing layer, and an internal structure (such as cross-shaped or grid-shaped baffles) that divides the internal cavity into multiple parallel channels. By combining the resistive silencing of the expansion chamber structure with the resistive silencing of porous sound-absorbing materials, they achieve a certain degree of suppression of broadband noise and airflow pulsation, and are widely used in the outlet pipelines of various types of fans.

[0004] However, in practical applications, it has been found that the existing fixed-structure impedance composite silencers still have significant drawbacks: their acoustic performance (such as silencing bandwidth and expansion ratio) is fixed after manufacturing, making them unable to adapt to large fluctuations in gas flow rate and velocity caused by changes in fan load and speed regulation. When the flow rate increases, the effective expansion ratio of the fixed silencer decreases relatively due to the unchanged inlet flow area, resulting in a decrease in the ability to suppress low-frequency and pulsating noise and a deterioration in the silencing effect. When the flow rate decreases, although the noise reduction requirements can be met, the fixed and smaller flow area will cause unnecessary pressure loss, leading to an increase in fan energy consumption. In other words, existing silencers lack the ability to self-adjust according to real-time operating conditions and cannot maintain optimal silencing performance and operating efficiency under varying operating conditions. This contradiction limits their further application in situations requiring frequent adjustments or with variable operating conditions. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide an impedance silencing device and its working method, which overcomes the shortcomings of traditional fixed structure impedance silencers that cannot adapt to changes in working conditions, resulting in performance degradation or increased energy consumption. It can automatically adjust according to gas flow rate and always maintain the optimal silencing effect and operating efficiency.

[0006] Technical solution:

[0007] An impedance-based silencing device includes a silencer cylinder, an inlet pipe and an outlet pipe located at both ends of the silencer cylinder, characterized in that it further includes a silencing component and a flow guiding mechanism disposed inside the silencer cylinder, wherein the inner diameter of the inlet pipe gradually increases along the airflow direction, and the inner diameter of the outlet pipe gradually decreases along the airflow direction, and the inlet pipe, the silencer cylinder, and the outlet pipe form an expansion chamber structure; the silencing component includes a silencing plate fixedly disposed inside the silencer cylinder and dividing the silencer cavity into multiple parallel silencing channels; the flow guiding mechanism includes a flow guiding cone disposed in the inlet pipe, and the flow guiding cone is connected to a control component for controlling its axial movement along the silencer cylinder.

[0008] Furthermore, both the air inlet duct and the air outlet duct are equipped with air guiding mechanisms.

[0009] Optionally, the taper of the guide cone at the air inlet duct position is the same as the taper of the inner cavity of the air inlet duct, and the taper of the guide cone at the air outlet duct position is the same as the taper of the inner cavity of the air outlet duct.

[0010] Optionally, the taper of the guide cone at the air inlet duct position is different from the taper of the inner cavity of the air inlet duct, and the taper of the guide cone at the air outlet duct position is different from the taper of the inner cavity of the air outlet duct.

[0011] Furthermore, the control assembly includes a slider, a lead screw, and a control motor that are fixedly connected to the guide cone. The slider is threadedly connected to the lead screw, and the lead screw is drivenly connected to the control motor.

[0012] Furthermore, the control motor is installed outside the muffler cylinder, and the control assembly also includes a transmission rod, a first steering helical gear, and a second steering helical gear. The transmission rod is connected to the output end of the control motor, the first steering helical gear is fixedly connected to the transmission rod, the second steering helical gear meshes with the first steering helical gear, and the lead screw is fixedly connected to the second steering helical gear.

[0013] Furthermore, the muffler plate has an internal mounting cavity, and the slider, lead screw, transmission rod, first steering helical gear, and second steering helical gear are all located inside the mounting cavity.

[0014] Furthermore, the control assembly also includes bearings for mounting the lead screw.

[0015] Furthermore, it also includes a control system, which includes a flow sensor for monitoring the gas flow rate or velocity within the pipeline and a controller; the controller is configured to control the operation of the control components based on signals from the flow sensor and the acoustic sensor.

[0016] The present invention also discloses a method for operating the above-mentioned impedance silencing device, comprising the following steps:

[0017] S1. Real-time data on gas flow rate or velocity passing through the silencer is obtained via a sensor;

[0018] S2. Control the axial movement of the guide cone according to the change in the flow rate or velocity data;

[0019] In step S2, when the flow rate or velocity increases, the guide cone is controlled to move outwards towards the corresponding duct to reduce the initial annular flow area between the guide cone and the inner wall of the duct; when the flow rate or velocity decreases, the guide cone is controlled to move inwards towards the silencer cylinder to increase the initial annular flow area.

[0020] Beneficial Effects: This invention, by incorporating axially movable variable-diameter guide cones in the inlet / outlet ducts, dynamically adjusts the position of the guide cones based on real-time monitored gas flow rate or velocity data, thereby altering the annular flow area at the air inlet. When the flow rate increases, the guide cones move outward to reduce the inlet area, actively increasing the system's effective expansion ratio and enhancing the resistance-based noise reduction effect, ensuring that the noise reduction performance does not decrease under high flow conditions. When the flow rate decreases, the guide cones move inward to increase the inlet area, significantly reducing airflow resistance and pressure loss while meeting basic noise reduction requirements. This allows the silencer to automatically adapt to the changing operating conditions of the fan, always operating near its optimal state. Attached Figure Description

[0021] Figure 1 This is a perspective view of the present invention;

[0022] Figure 2 This is an exploded view of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal structure of the present invention in a cross-section state;

[0024] Figure 4 This is a cross-sectional view showing that the guide cone of the present invention has the same taper as the inner cavity of the inlet and outlet air ducts;

[0025] Figure 5 This is a cross-sectional view showing that the taper of the guide cone of the present invention is greater than the taper of the inner cavity of the inlet and outlet air ducts;

[0026] Figure 6 This is a cross-sectional view of the present invention where the taper of the guide cone is smaller than the taper of the inner cavity of the inlet and outlet air duct. Detailed Implementation

[0027] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] like Figure 1-4As shown, an impedance silencing device includes a silencer cylinder 1, an inlet pipe 2 and an outlet pipe 3 located at both ends of the silencer cylinder 1. The device is characterized by further including a silencing component 4 and a flow guiding mechanism 5 disposed inside the silencer cylinder 1. The inner diameter of the inlet pipe 2 gradually increases along the airflow direction, while the inner diameter of the outlet pipe 3 gradually decreases along the airflow direction. The inlet pipe 2, the silencer cylinder 1, and the outlet pipe 3 form an expansion chamber structure. The silencing component 4 includes a silencing plate 41 fixedly disposed inside the silencer cylinder 1 and dividing the silencer cavity into multiple parallel silencing channels. The flow guiding mechanism 5 includes a flow guiding cone 51 disposed in the inlet pipe 2, and the flow guiding cone 51 is connected to a control component 52 for controlling its axial movement along the silencer cylinder 1. This structure is based on the expansion chamber principle in acoustics. Through the gradually expanding design of the inlet pipe 2, the airflow smoothly enters the silencer cylinder 1 with a larger cross-sectional area, creating a sudden change in acoustic impedance. Sound waves undergo reflection and interference at points of abrupt change in cross-section, thus consuming sound energy, especially effective for low-frequency noise and airflow pulsation. The anechoic panel 41 divides the large cavity into multiple parallel smaller channels, maintaining structural strength while increasing the contact area between airflow and sound-absorbing material, thereby enhancing the resistive noise reduction effect.

[0030] Both the inlet duct 2 and the outlet duct 3 are equipped with flow guiding mechanisms 5. The presence of flow guiding mechanisms 5 at both the inlet and outlet ends enables active control of the entire flow path. The flow guiding cone 51 at the inlet duct 2 primarily adjusts the inlet conditions, controlling the airflow state and acoustic inlet impedance entering the expansion chamber; the flow guiding cone 51 at the outlet duct 3 adjusts the exhaust conditions, optimizes the airflow pattern, and reduces outlet turbulence and regenerated noise. Together, these mechanisms enhance overall noise reduction stability and flow field quality.

[0031] In this embodiment, the taper of the guide cone 41 at the air inlet duct 2 is the same as the taper of the inner cavity of the air inlet duct 2, and the taper of the guide cone 41 at the air outlet duct 3 is the same as the taper of the inner cavity of the air outlet duct 3. The radial gap between the outer surface of the guide cone 51 and the inner wall of the duct remains constant along the axial direction. At this time, the cross-sectional area of ​​the annular flow channel will change linearly along the airflow direction. For the air inlet duct 2, the airflow flows from the smaller diameter end to the larger diameter end, and the flow area gradually expands, causing the airflow to naturally expand and decelerate during the delivery process. This reduces the direct impact of the airflow on the surface of the guide cone 51 on the airflow, and allows the airflow to transition more smoothly into the space of the subsequent silencer cylinder 1, effectively suppressing the eddies and separation losses caused by the abrupt change in cross-section, and creating a more uniform flow field condition for efficient dissipation of sound energy.

[0032] Optionally, the taper of the guide cone 41 at the air inlet duct 2 can also be different from the taper of the inner cavity of the air inlet duct 2, and the taper of the guide cone 41 at the air outlet duct 3 can be different from the taper of the inner cavity of the air outlet duct 3.

[0033] like Figure 5As shown, the taper of the guide cone 51 is greater than the taper of the duct cavity. At this point, the gap gradually converges along the airflow direction, causing the airflow to decelerate slowly or even accelerate, which can enhance turbulent mixing and sound energy dissipation, but at the cost of increased flow resistance. Figure 6 As shown, the taper of the guide cone 51 is smaller than the taper of the duct cavity, and the gap gradually expands along the airflow direction, causing the airflow to decelerate and diffuse, which is beneficial for pressure recovery and reducing outlet losses. This design is suitable for applications with strict pressure loss requirements. Different combinations of tapers provide flexible design means to match specific noise spectra and flow resistance characteristics.

[0034] The control component 52 includes a slider 521, a lead screw 522, and a control motor 523 fixedly connected to the guide cone. The slider 521 is threadedly connected to the lead screw 522, and the lead screw 522 is driven by the control motor 523. The helical transmission mechanism formed by the slider 521 and the lead screw 522 can accurately convert the rotational motion of the control motor 523 into the linear displacement of the guide cone 51. This transmission method has high precision, high rigidity, and self-locking characteristics, which can ensure that the guide cone 51 maintains a stable position under continuous aerodynamic load and avoids drift due to pressure fluctuations.

[0035] The control motor 523 is installed outside the muffler cylinder 1. The control assembly 52 also includes a transmission rod 524, a first helical gear 525, and a second helical gear 526. The transmission rod 524 is connected to the output end of the control motor 523. The first helical gear 525 is fixedly connected to the transmission rod 524. The second helical gear 526 meshes with the first helical gear 525. The lead screw 522 is fixedly connected to the second helical gear 526. Placing the control motor 523 outside the muffler cylinder 1 keeps it away from the high temperature, high humidity, and dusty airflow environment inside, significantly improving the reliability and lifespan of the drive components. The transmission rod 524 transmits power into the device. Through the spatial gear pair formed by the first helical gear 525 and the second helical gear 526, the axial rotation of the transmission rod 524 is converted into the radial rotation required by the lead screw 522, realizing spatial decoupling and efficient power transmission between the external power source and the internal linear actuator.

[0036] The muffler plate 41 has an internal mounting cavity, where the slider 521, lead screw 522, transmission rod 524, first steering helical gear 525, and second steering helical gear 526 are all housed. Integrating most of the precision components of the drive and control system into the mounting cavity within the muffler plate 41 achieves a highly compact, integrated design. This layout effectively protects the transmission mechanism from direct airflow, oil contamination, and corrosion, while also avoiding the need for additional acoustic treatment space within the muffler cavity, ensuring the effective volume of the muffler cylinder 1, and helping to isolate any weak noise that may be generated by mechanical movement.

[0037] It also includes a control system, which includes a flow sensor for monitoring the flow rate or velocity of gas in the pipeline and a controller; the controller is configured to control the operation of the control component 52 based on the signals from the flow sensor and the acoustic sensor.

[0038] The controller (typically a programmable logic controller (PLC) or an embedded microprocessor) receives and processes analog or digital signals from these sensors at the hardware level. At the software level, its built-in control strategy is key to achieving adaptive optimization. The core of this strategy is a pre-defined "condition-position" mapping rule base based on expert experience and experimental data; essentially, it's a multi-dimensional lookup table. This rule base takes "flow rate value" and "noise spectrum characteristics" as input conditions and "optimal position of the guide cone" as the output target.

[0039] The specific execution process of the control strategy is as follows: First, the controller smooths the real-time collected flow signal and compares it with the set flow threshold range to determine whether the system is in a high, medium, or low load range. Simultaneously, it analyzes the noise spectrum to identify the peak noise frequencies that need to be suppressed. Then, the controller uses the current "flow range" and "dominant noise frequency" as a joint query key, performs matching and interpolation calculations in a preset rule base, and finally calculates the precise target position coordinates of the guide cone 51 under the current operating conditions in real time. This position coordinate is designed to achieve specific objectives: for example, when the flow rate is high and low-frequency noise is prominent, priority is given to ensuring high noise reduction, and the calculated position will cause the guide cone to move outward to reduce the inlet area; when the flow rate is low and the noise level meets the standard, priority is given to low flow resistance, and the calculated position will cause the guide cone to move inward to increase the inlet area.

[0040] After calculating the target position, the controller sends a command to the control motor 523 in the control component 52 through its digital or analog output interface. The control motor 523 drives the lead screw 522 to rotate, which in turn drives the guide cone 51 to move axially via the slider 521. The actual position of the guide cone 51 can be obtained through a closed-loop position feedback formed by a rotary encoder linked to the lead screw 522 or an independent displacement sensor, ensuring movement accuracy. When the guide cone 51 reaches the target position, the system enters steady-state monitoring, waiting for the next change in operating conditions to trigger a new adjustment cycle. Through the above-mentioned closed-loop control process of real-time sensing, strategy matching, precise execution, and feedback confirmation, the system can dynamically adjust the inlet acoustic impedance and fluid resistance characteristics of the silencer, thereby automatically maintaining the optimal balance between noise reduction performance and operating energy consumption across the entire operating range.

[0041] Example 2

[0042] The present invention also discloses a method for operating the above-mentioned impedance silencing device, comprising the following steps:

[0043] S1. Real-time data on gas flow rate or velocity passing through the silencer is obtained via a sensor;

[0044] S2. Control the axial movement of the guide cone 51 according to the change in the flow rate or flow velocity data;

[0045] In step S2, when the flow rate or velocity increases, the guide cone 51 is controlled to move outward in the direction of the corresponding duct to reduce the initial annular flow area between the guide cone 51 and the inner wall of the duct; when the flow rate or velocity decreases, the guide cone 51 is controlled to move inward in the silencer cylinder 1 to increase the initial annular flow area.

[0046] The principle of this method lies in maintaining the optimal operating point of the silencer by dynamically adjusting the inlet geometry. When an increase in flow rate is detected, the controller instructs the guide cone 51 to move outwards from the duct. At this time, the thicker part of the guide cone 51 enters or gets closer to the throat of the duct, reducing the initial annular flow area. According to the expansion chamber silencing theory, the effective expansion ratio of the silencer is determined by the ratio of the cross-sectional area of ​​the silencer cylinder 1 to the inlet flow area. The decrease in the expansion ratio directly leads to an increase in the expansion ratio, thereby significantly enhancing the silencer's resistance to low-frequency noise and compensating for the insufficient silencing that may be caused by increased flow rate and increased sound source intensity.

[0047] When a decrease in flow rate is detected, the controller instructs the guide cone 51 to move inward toward the inside of the silencer cylinder 1. At this time, the thinner part of the guide cone 51 is located at the throat of the duct, increasing the initial area of ​​the annular flow and thus reducing the expansion ratio. Although the resistance silencing effect is weakened, the local drag coefficient of the airflow is significantly reduced, resulting in a significant decrease in the pressure difference before and after the device. Since the noise source intensity is already low under low flow conditions, appropriately reducing the silencing intensity can still meet environmental protection requirements, and the reduction in flow resistance directly translates into energy savings for the fan, achieving energy-saving operation.

[0048] The entire working process forms a closed-loop adaptive system. The device senses changes in operating conditions through real-time sensors, and the controller makes decisions based on preset strategies, driving the guide cone 51 to precisely adjust its position, thereby changing the acoustic characteristics of the silencer in real time, and ultimately achieving an automatic optimal balance between the device's noise reduction performance and operating economy under varying operating conditions.

[0049] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An impedance silencing device, comprising a silencer cylinder (1), an air inlet pipe (2) and an air outlet pipe (3) located at both ends of the silencer cylinder (1), characterized in that, It also includes a silencing component (4) and a flow guiding mechanism (5) disposed inside the silencer cylinder (1). The inner diameter of the air inlet pipe (2) gradually increases along the airflow direction, and the inner diameter of the air outlet pipe (3) gradually decreases along the airflow direction. The air inlet pipe (2), the silencer cylinder (1), and the air outlet pipe (3) form an expansion chamber structure. The silencing component (4) includes a silencing plate (41) fixedly disposed inside the silencer cylinder (1) and dividing the silencer cavity into multiple parallel silencing channels. The flow guiding mechanism (5) includes a flow guiding cone (51) disposed in the air inlet pipe (2). The flow guiding cone (51) is connected to a control component (52) for controlling its axial movement along the silencer cylinder (1).

2. The impedance silencing device according to claim 1, characterized in that, Both the air inlet pipe (2) and the air outlet pipe (3) are equipped with a flow guiding mechanism (5).

3. The impedance silencing device according to claim 2, characterized in that, The taper of the guide cone (41) at the air inlet pipe (2) is the same as the taper of the inner cavity of the air inlet pipe (2), and the taper of the guide cone (41) at the air outlet pipe (3) is the same as the taper of the inner cavity of the air outlet pipe (3).

4. The impedance silencing device according to claim 1, characterized in that, The taper of the guide cone (41) at the air inlet pipe (2) is different from the taper of the inner cavity of the air inlet pipe (2), and the taper of the guide cone (41) at the air outlet pipe (3) is different from the taper of the inner cavity of the air outlet pipe (3).

5. The impedance silencing device according to claim 1, characterized in that, The control component (52) includes a slider (521), a lead screw (522), and a control motor (523) that are fixedly connected to the guide cone. The slider (521) is threadedly connected to the lead screw (522), and the lead screw (522) is drivenly connected to the control motor (523).

6. The impedance silencing device according to claim 5, characterized in that, The control motor (523) is installed outside the muffler cylinder (1). The control assembly (52) also includes a transmission rod (524), a first steering helical gear (525), and a second steering helical gear (526). The transmission rod (524) is connected to the output end of the control motor (523). The first steering helical gear (525) is fixedly connected to the transmission rod (524). The second steering helical gear (526) is meshed with the first steering helical gear (525). The lead screw (522) is fixedly connected to the second steering helical gear (526).

7. The impedance silencing device according to claim 6, characterized in that, The muffler plate (41) has an installation cavity inside, and the slider (521), lead screw (522), transmission rod (524), first steering helical gear (525), and second steering helical gear (526) are all located inside the installation cavity.

8. The impedance silencing device according to claim 6, characterized in that, The control assembly (52) also includes a bearing (527) for mounting the lead screw (522).

9. The impedance silencing device according to claim 1, characterized in that, It also includes a control system, which includes a flow sensor for monitoring the flow rate or velocity of gas in the pipeline and a controller; the controller is configured to control the operation of the control component (52) based on the signals from the flow sensor and the acoustic sensor.

10. A method of operating the impedance silencing device as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Real-time data on gas flow rate or velocity passing through the silencer is obtained via a sensor; S2. Control the axial movement of the guide cone (51) according to the change of the flow rate or velocity data; In step S2, when the flow rate or velocity increases, the guide cone (51) is controlled to move outward in the direction of the corresponding duct to reduce the initial annular flow area between the guide cone (51) and the inner wall of the duct; when the flow rate or velocity decreases, the guide cone (51) is controlled to move inward in the direction of the silencer cylinder (1) to increase the initial annular flow area.

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