Reverse convection air exhaust device based on independent double motor control

Abstract

The application relates to the technical field of industrial ventilation, and discloses a reverse convection exhaust device based on independent double-motor control, which comprises a shell, a mixing cavity formed in the shell, an air inlet and an air outlet arranged at the axial two ends of the shell respectively, a main fan blade group arranged in the mixing cavity and close to one side of the air inlet and configured to rotate along a first direction around a central axis, a secondary fan blade group coaxially nested with the main fan blade group, arranged in the mixing cavity and close to one side of the air outlet, and configured to rotate along a second direction opposite to the first direction around the central axis, and a first motor drivingly connected with the main fan blade group and used for driving the main fan blade group to rotate. By monitoring the wind resistance change in real time and dynamically adjusting the rotating speed difference, the deflected airflow intersection area is re-constrained in the center of the mixing cavity, the integrity of the spiral accelerating flow field is maintained, and the efficiency cliff drop caused by the collapse of the flow field is avoided.

Description

Technical Field

[0001] This invention relates to the field of industrial ventilation technology, specifically to a reverse convection exhaust device based on independent dual-motor control. Background Technology

[0002] Axial flow fans are widely used for gas replacement in industrial ventilation. To improve exhaust efficiency, coaxial counter-rotating double-blade structures have been applied, which generate a synergistic aerodynamic effect through the counter-rotation of two stages of impellers.

[0003] In addition, although there are single-blade fans using variable frequency speed control in the existing technology, they can only adjust the speed of a single-stage fan blade, and cannot achieve coordinated control of two-stage counter-rotating fan blades, let alone solve the dynamic stability problem of the two-stage airflow convergence zone.

[0004] In summary, the existing technology lacks an exhaust device that can dynamically adjust the speed of the two-stage fan blades according to real-time operating conditions and actively maintain the stability of the spiral acceleration flow field in the mixing chamber. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a reverse convection exhaust device based on independent dual-motor control, which solves the problems of flow field collapse, efficiency reduction, and noise surge under variable wind resistance conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a reverse convection exhaust device based on independent dual-motor control, comprising:

[0007] The housing has a mixing chamber inside, and an air inlet and an air outlet are respectively provided at both axial ends of the housing;

[0008] The main fan blade assembly is located in the mixing chamber on the side near the air inlet and is configured to rotate around the central axis in a first direction;

[0009] The auxiliary fan blade assembly, coaxially nested with the main fan blade assembly, is located in the mixing chamber near the air outlet and is configured to rotate around the central axis in a second direction opposite to the first direction.

[0010] A first motor is driven and connected to the main fan blade assembly to drive the main fan blade assembly to rotate. The outer wall of the first motor is fixedly connected with a uniformly distributed second fixing plate, and the second fixing plate is fixedly connected to the inner wall of the outer casing.

[0011] The second motor is driven and connected to the auxiliary fan blade group to drive the auxiliary fan blade group to rotate. The rated power of the second motor is 0.6 to 0.8 times that of the first motor. The outer wall of the second motor is fixedly connected with a uniformly distributed first fixing plate, and the first fixing plate is fixedly connected to the inner wall of the outer shell.

[0012] The controller is electrically connected to both the first motor and the second motor, and is configured to:

[0013] The operating parameters of the first motor and the second motor are acquired in real time, including speed and drive current;

[0014] Based on the aforementioned operating parameters, calculate the wind resistance characteristic value reflecting the external wind resistance state;

[0015] The target rotational speed difference is determined based on the comparison between the wind resistance characteristic value and the preset threshold.

[0016] The speeds of the first motor and the second motor are independently adjusted so that the actual speed difference between the main fan blade group and the auxiliary fan blade group approaches the target speed difference, thereby maintaining the stability of the spiral acceleration flow field in the mixing chamber.

[0017] A rectifier grid is disposed between the mixing chamber and the air outlet. The rectifier grid includes a plurality of honeycomb-shaped through holes with a diameter of 6mm to 10mm.

[0018] Preferably, the main fan blade group adopts asymmetric airfoil blades with a blade installation angle of 30° to 40° and 6 to 8 blades; the auxiliary fan blade group adopts asymmetric airfoil blades with a blade installation angle of 25° to 32° and 1 to 3 more blades than the main fan blade group.

[0019] Preferably, the wind resistance characteristic value is the speed attenuation rate of the first motor and the second motor, and the speed attenuation rate is the ratio of the current speed to the rated speed;

[0020] The controller is configured to: increase the target speed difference when the speed decay rate is lower than a first preset threshold; and decrease the target speed difference when the speed decay rate is higher than a second preset threshold; wherein the first preset threshold is less than the second preset threshold.

[0021] Preferably, the adjustment range of the target speed difference is 150 rpm to 400 rpm.

[0022] Preferably, the controller is further configured to: while maintaining the stability of the spiral acceleration flow field, adjust the speed combination of the first motor and the second motor with the optimization goal of minimizing the combined operating noise of the first motor and the second motor.

[0023] Preferably, it also includes a wind pressure sensor, which is disposed at the air outlet and electrically connected to the controller, for detecting the static pressure value of the air outlet; the wind resistance characteristic value also includes the static pressure value.

[0024] Preferably, it also includes a flow collector shroud, which is disposed at the air inlet, and the inner wall surface of the flow collector shroud is a conical expansion surface with an expansion angle of 12° to 18°.

[0025] Preferably, a control method for a reverse convection exhaust device based on independent dual-motor control, applied to the exhaust device as described in any one of claims 1-7, is characterized by comprising the following steps:

[0026] S1: Start the first motor and the second motor to drive the main fan blade group and the auxiliary fan blade group to rotate in opposite directions at a preset initial speed;

[0027] S2: Real-time acquisition of the operating parameters of the first motor and the second motor, the operating parameters including speed and drive current;

[0028] S3: Calculate the wind resistance characteristic value based on the operating parameters, where the wind resistance characteristic value reflects the current external wind resistance status;

[0029] S4: Determine whether the wind resistance characteristic value exceeds the preset stable range;

[0030] S5: If the wind resistance characteristic value exceeds the preset stable range, calculate the target speed difference based on the wind resistance characteristic value, and independently adjust the speed of the first motor and the second motor to make the actual speed difference approach the target speed difference, so as to maintain the stability of the spiral acceleration flow field in the mixing cavity.

[0031] S6: If the wind resistance characteristic value is within the preset stable range, then maintain the current speed operation.

[0032] Preferably, the step S5 of calculating the target speed difference based on the wind resistance characteristic value includes:

[0033] A mapping relationship is established between the wind resistance characteristic value and the target speed difference, wherein the mapping relationship is as follows: when the wind resistance characteristic value increases, the target speed difference increases accordingly;

[0034] The mapping relationship is determined based on the following principle: increasing the speed difference can enhance the constraint effect of the tangential airflow generated by the secondary fan blade group, and re-constrain the axial airflow that diffuses outward due to the increase in back pressure to the central region of the mixing chamber, thereby maintaining the integrity and stability of the spiral acceleration flow field.

[0035] Preferably, step S5 further includes: while adjusting the speed difference, with the goal of minimizing overall operating noise, and under the premise of meeting air volume requirements, selecting the speed combination with the lowest noise from multiple feasible speed combinations.

[0036] This invention provides a reverse convection exhaust device based on independent dual-motor control. It has the following beneficial effects:

[0037] 1. Dynamic stability of the flow field: By monitoring the changes in wind resistance in real time and dynamically adjusting the speed difference, the deflected airflow convergence area is re-constrained to the center of the mixing chamber, maintaining the integrity of the spiral acceleration flow field and avoiding the precipitous drop in efficiency caused by the collapse of the flow field.

[0038] 2. High-efficiency operation under wide operating conditions: It can maintain stable exhaust efficiency under operating conditions with wind resistance variation range of 0 to 200 Pa, without the need for shutdown or manual adjustment;

[0039] 3. Active noise reduction: Under the premise of maintaining flow field stability, select rotational speed combinations with noise minimization as the optimization goal to suppress the generation of turbulent noise from the source;

[0040] 4. High reliability: Electronic control replaces the complex mechanical transmission mechanism, eliminating mechanical shock and wear, and extending the service life of the equipment. Attached Figure Description

[0041] Figure 1 This is a perspective view of the present invention;

[0042] Figure 2 This is a schematic diagram of the controller structure of the present invention;

[0043] Figure 3 This is a cross-sectional perspective view of the present invention;

[0044] Figure 4 This is a cross-sectional view of the present invention.

[0045] Among them, 1. Main fan blade group; 2. Auxiliary fan blade group; 3. Mixing chamber; 4. Rectifier grid; 5. Collector cover; 6. First motor; 7. Second motor; 8. Controller; 9. Wind pressure sensor; 10. Housing; 11. Air inlet; 12. Air outlet; 13. Air outlet duct; 14. First fixing plate; 15. Second fixing plate. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example:

[0048] Please see the appendix Figure 1 - Appendix Figure 4 The present invention provides a reverse convection exhaust device based on independent dual motor control, including a housing 10, a cylindrical mixing chamber 3 formed inside the housing 10, an air inlet 11 at the left end of the housing 10 and an air outlet 12 at the right end.

[0049] Inside the housing 10, a flow collector 5, a main fan blade group 1, a secondary fan blade group 2, and a rectifier grid 4 are arranged sequentially along the airflow direction.

[0050] The main fan blade assembly 1 is driven by the first motor 6 and rotates clockwise around the central axis. The main fan blade assembly 1 adopts asymmetric airfoil blades with a blade installation angle of 35° and a number of 6 blades.

[0051] The auxiliary fan blade group 2 is coaxially nested with the main fan blade group 1 and is driven by the second motor 7 to rotate counterclockwise around the central axis. The auxiliary fan blade group 2 adopts asymmetric airfoil blades with a blade installation angle of 28° and 8 blades (2 more than the main fan blade group 1).

[0052] Both the first motor 6 and the second motor 7 are variable frequency motors with rated powers of P1 and P2, respectively, where P2 = 0.7P1. The power of the second motor 7 is less than that of the first motor 6 because the main function of the auxiliary fan blade assembly 2 is to provide tangential constraint for airflow rather than the main axial thrust.

[0053] Controller 8 is a DSP-based microcontroller, electrically connected to the first motor 6 and the second motor 7. Controller 8 acquires the speed of the two motors in real time through Hall effect sensors and the drive current of the two motors in real time through current sensors.

[0054] The wind pressure sensor 9 is located at the air outlet 12 and is electrically connected to the controller 8. It is used to detect the static pressure value of the air outlet 12.

[0055] The rectifier grid 4 is located between the mixing chamber 3 and the air outlet 12, and includes multiple honeycomb-shaped through holes with a diameter of 8 mm, which are used to eliminate the tangential velocity component of the spiral airflow.

[0056] The air intake shroud 5 is located at the air inlet 11. Its inner wall is a conical expansion surface with an expansion angle of 15°, which is used to make the airflow transition smoothly.

[0057] Control Logic Description

[0058] The core control logic of controller 8 is as follows:

[0059] 1. Calculation of wind resistance characteristic value: The controller 8 calculates the speed attenuation rate η of the first motor 6 and the second motor 7 in real time, where η = (current speed / rated speed) × 100%. When the external wind resistance increases, the motor load increases, the speed decreases, and the speed attenuation rate η decreases.

[0060] 2. Determination of target speed difference: Preset mapping relationship table within controller 8:

[0061] When η≥95%, the target speed difference ΔV=150rpm;

[0062] When 85%≤η<95%, the target speed difference ΔV=250rpm;

[0063] When 75%≤η<85%, the target speed difference ΔV=350rpm;

[0064] When η < 75%, the target speed difference ΔV = 400 rpm.

[0065] 3. Speed ​​Regulation: The controller 8 independently regulates the speeds of the first motor 6 and the second motor 7, making the actual speed difference approach the target speed difference ΔV. Increasing the speed difference enhances the constraint effect of the tangential airflow generated by the auxiliary fan blade group 2, and re-constrains the axial airflow that diffuses outward due to the increased back pressure to the central region of the mixing chamber 3, thereby maintaining the stability of the spiral acceleration flow field.

[0066] 4. Noise Reduction Optimization: While maintaining the target speed difference, controller 8 optimizes by minimizing the overall operating noise of the two motors, selecting the speed combination with the lowest noise from multiple feasible speed combinations. For example, when the target speed difference is 250 rpm, it can select either (main fan blade group 1200 rpm + auxiliary fan blade group 1450 rpm) or (main fan blade group 1500 rpm + auxiliary fan blade group 1750 rpm), and controller 8 selects the speed combination with the lower noise.

[0067] Example 2

[0068] The difference between this embodiment and Embodiment 1 lies in the adjustment of the control strategy:

[0069] The blade installation angle of the main fan blade group 1 is 32°, the blade installation angle of the auxiliary fan blade group 2 is 26°, and the adjustment range of the target speed difference ΔV is 180rpm~350rpm.

[0070] This embodiment is suitable for scenarios where wind resistance changes relatively gradually and noise control requirements are high. A smaller blade installation angle can reduce the aerodynamic noise baseline, and a narrower speed difference adjustment range can avoid frequent speed switching.

[0071] Example 3

[0072] The difference between this embodiment and Embodiment 1 is that:

[0073] The blade installation angle of the main fan blade group 1 is 38°, the blade installation angle of the auxiliary fan blade group 2 is 30°, and the adjustment range of the target speed difference ΔV is 200rpm~400rpm.

[0074] This embodiment is suitable for industrial ventilation scenarios with drastic changes in wind resistance and high requirements for exhaust volume. A larger blade installation angle can provide greater basic thrust, and a wider range of speed difference adjustment can cope with greater wind resistance fluctuations.

[0075] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A reverse convection exhaust device based on independent dual-motor control, characterized in that, include: The housing (10) has a mixing chamber (3) inside. An air inlet (11) and an air outlet (12) are respectively provided at both ends of the axial direction of the housing (10). A (13) is provided on one side of the housing (10). The main fan blade assembly (1) is located in the mixing chamber (3) on one side near the air inlet (11) and is configured to rotate around the central axis in a first direction; The auxiliary fan blade group (2) is coaxially nested with the main fan blade group (1) and is located in the mixing chamber (3) on the side near the air outlet (12). It is configured to rotate around the central axis in a second direction opposite to the first direction. The first motor (6) is driven and connected to the main fan blade group (1) to drive the main fan blade group (1) to rotate. The outer wall of the first motor (6) is fixedly connected with a uniformly distributed second fixing plate (15), and the second fixing plate (15) is fixedly connected to the inner wall of the outer shell (10). The second motor (7) is driven and connected to the auxiliary fan blade group (2) to drive the auxiliary fan blade group (2) to rotate. The rated power of the second motor (7) is 0.6 to 0.8 times the rated power of the first motor (6). The outer wall of the second motor (7) is fixedly connected with a uniformly distributed first fixing plate (14), and the first fixing plate (14) is fixedly connected to the inner wall of the outer shell (10). The controller (8) is electrically connected to the first motor (6) and the second motor (7) respectively, and the controller (8) is configured to: The operating parameters of the first motor (6) and the second motor (7) are acquired in real time, including the speed and drive current; Based on the aforementioned operating parameters, calculate the wind resistance characteristic value reflecting the external wind resistance state; The target rotational speed difference is determined based on the comparison between the wind resistance characteristic value and the preset threshold. The speeds of the first motor (6) and the second motor (7) are independently adjusted so that the actual speed difference between the main fan blade group (1) and the auxiliary fan blade group (2) approaches the target speed difference, thereby maintaining the stability of the spiral acceleration flow field in the mixing chamber (3). A rectifier grid (4) is disposed between the mixing chamber (3) and the air outlet (12). The rectifier grid (4) includes a plurality of honeycomb-shaped through holes with a diameter of 6 mm to 10 mm.

2. The exhaust device according to claim 1, characterized in that, The main fan blade group (1) adopts asymmetric airfoil blades with a blade installation angle of 30° to 40° and a number of blades of 6 to 8; the auxiliary fan blade group (2) adopts asymmetric airfoil blades with a blade installation angle of 25° to 32° and a number of blades of 1 to 3 more than that of the main fan blade group (1).

3. The exhaust device according to claim 1, characterized in that, The wind resistance characteristic value is the speed attenuation rate of the first motor (6) and the second motor (7), and the speed attenuation rate is the ratio of the current speed to the rated speed; The controller is configured to: increase the target speed difference when the speed decay rate is lower than a first preset threshold; and decrease the target speed difference when the speed decay rate is higher than a second preset threshold; wherein the first preset threshold is less than the second preset threshold.

4. The exhaust device according to claim 1, characterized in that, The target speed difference can be adjusted within a range of 150 rpm to 400 rpm.

5. The exhaust device according to claim 1, characterized in that, The controller is also configured to: while maintaining the stability of the spiral acceleration flow field, adjust the speed combination of the first motor (6) and the second motor (7) with the optimization goal of minimizing the combined operating noise of the first motor (6) and the second motor (7).

6. The exhaust device according to claim 1, characterized in that, It also includes a wind pressure sensor (9), which is located at the air outlet (12) and electrically connected to the controller, for detecting the static pressure value of the air outlet (12); the wind resistance characteristic value also includes the static pressure value.

7. The exhaust device according to claim 1, characterized in that, It also includes a flow collector (5), which is located at the air inlet (11). The inner wall of the flow collector (5) is a conical expansion surface with an expansion angle of 12° to 18°.

8. A control method for a reverse convection exhaust device based on independent dual-motor control, applied to the exhaust device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Start the first motor and the second motor to drive the main fan blade group and the auxiliary fan blade group to rotate in opposite directions at a preset initial speed; S2: Real-time acquisition of the operating parameters of the first motor and the second motor, the operating parameters including speed and drive current; S3: Calculate the wind resistance characteristic value based on the operating parameters, where the wind resistance characteristic value reflects the current external wind resistance status; S4: Determine whether the wind resistance characteristic value exceeds the preset stable range; S5: If the wind resistance characteristic value exceeds the preset stable range, calculate the target speed difference based on the wind resistance characteristic value, and independently adjust the speed of the first motor and the second motor to make the actual speed difference approach the target speed difference, so as to maintain the stability of the spiral acceleration flow field in the mixing cavity. S6: If the wind resistance characteristic value is within the preset stable range, then maintain the current speed operation.

9. The control method according to claim 8, characterized in that, Step S5, which involves calculating the target speed difference based on the drag characteristic value, includes: A mapping relationship is established between the wind resistance characteristic value and the target speed difference, wherein the mapping relationship is as follows: when the wind resistance characteristic value increases, the target speed difference increases accordingly; The mapping relationship is determined based on the following principle: increasing the speed difference can enhance the constraint effect of the tangential airflow generated by the secondary fan blade group, and re-constrain the axial airflow that diffuses outward due to the increase in back pressure to the central region of the mixing chamber, thereby maintaining the integrity and stability of the spiral acceleration flow field.

10. The control method according to claim 8, characterized in that, Step S5 also includes: while adjusting the speed difference, with the goal of minimizing overall operating noise, and under the premise of meeting air volume requirements, selecting the speed combination with the lowest noise from multiple feasible speed combinations.

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