A range hood and control method

Abstract

The application discloses a range hood, which comprises a smoke exhaust fan, a wind curtain module and a wind curtain air control module. The wind curtain module introduces part of the smoke discharged by the smoke exhaust fan to form a wind curtain with a downward component. The wind curtain air control module controls the wind curtain air speed by adjusting the rotating speed of the smoke exhaust fan according to the back pressure, and forms multi-stage control. The range hood provided by the application can generate a wind curtain without using an independent wind curtain fan, and can control the wind curtain air speed in multiple stages by adjusting the rotating speed of the smoke exhaust fan according to the back pressure, so that the control of the wind curtain air speed of the range hood is more in line with the actual use of the range hood, and the use effect of the wind curtain is improved.

Description

Technical Field

[0001] This invention belongs to the field of range hood technology, specifically relating to a range hood and its control method. Background Technology

[0002] Air curtain range hoods generate an air curtain that prevents cooking fumes from escaping, effectively reducing kitchen pollution and harm to people, and allowing the hood to remove more fumes. Current air curtain range hoods generate the air curtain using independent fans. Controlling the airflow speed requires a variable frequency fan, which is costly. This also complicates the structure of the air curtain assembly and the range hood's electrical circuitry, while increasing energy consumption, making them less energy-efficient. Summary of the Invention

[0003] The purpose of this invention is to provide a range hood that can generate an air curtain without the need for an additional independent air curtain fan, and the air curtain speed can be controlled in multiple stages by adjusting the speed of the exhaust fan according to the back pressure.

[0004] The present invention is implemented as follows: a range hood includes a smoke exhaust fan, an air curtain module, and an air curtain control module. The air curtain module introduces part of the smoke exhausted by the smoke exhaust fan to form an air curtain with a downward component. The air curtain control module controls the air curtain speed by adjusting the rotation speed of the smoke exhaust fan according to the back pressure, and forms multi-segment control.

[0005] Optionally, the air curtain module includes a guide air vent on the smoke exhaust fan housing and an air curtain assembly located at the guide air vent inside the smoke exhaust fan housing. The air curtain assembly includes an air curtain housing, which includes a detachably connected upper air curtain cover and a lower air curtain cover. The upper air curtain cover has an inlet for introducing part of the exhaust gas discharged by the smoke exhaust fan. The lower air curtain cover has an outlet, and a guide is provided between the upper and lower air curtain covers. The exhaust air from the outlet of the air curtain assembly is discharged through the guide air vent, forming an air curtain with a downward component.

[0006] Optionally, the air curtain cover has a convex cover body, which forms a pressure stabilizing cavity with the guide member. The pressure stabilizing cavity is connected to the inlet, which is located in the middle of the pressure stabilizing cavity. The convex cover body forms an inner cavity surface that expands to the left and right with the inlet as the center. The angle range of the inner cavity surface is 120°-160°. An inlet pipe is provided at the inlet, which communicates with the pressure stabilizing cavity through the inlet. The inlet pipe forms a downward included angle with an angle range of 0°-90°.

[0007] Optionally, the air curtain module further includes a bypass ventilation component, which includes a bypass ventilation pipe section. One end of the bypass ventilation pipe section is connected to the exhaust port of the exhaust fan, and the other end is provided with a connecting pipe structure. The connecting pipe structure is used to connect to the exhaust pipe. The bypass ventilation pipe section is provided with a connection port and a check valve. The connection port is connected to the inlet provided on the air curtain cover through a slender pipe.

[0008] Optionally, the air curtain control module includes a target air volume control unit and a target power control unit; in the target air volume control unit, by controlling the speed of the exhaust fan, the exhaust fan operates in a relatively stable operating state with a corresponding operating power and air volume under different back pressures; in the target power control unit, by controlling the speed of the exhaust fan, the exhaust fan operates in a relatively stable operating state with a corresponding operating power and air volume under different back pressures.

[0009] Optionally, the target power control unit and the target air volume control unit can switch within a certain back pressure range, which is 150-450 Pa; wherein the back pressure corresponding to the target power control unit is higher than the back pressure corresponding to the target air volume control unit.

[0010] Optionally, the back pressure range of the target air volume control unit is 0-250 Pa; the relatively stable air volume means that different target exhaust air volumes are adopted according to different exhaust fan speeds, and the higher the exhaust fan speed, the higher the target air volume is adopted, and the actual exhaust air volume generated by the exhaust fan is within ±15% of the target air volume.

[0011] Optionally, in the target power control unit, the higher the speed of the exhaust fan, the higher the target power is used; the relatively stable operating power means that the operating power is within ±8% of the actual constant power operating state.

[0012] A control method for a range hood, wherein, for the same air volume, the relationship between the power P and the rotational speed n of the exhaust fan motor satisfies the following formula:

[0013] P = An 3 +Bn 3 +Cn+D

[0014] In the formula, P is the power of the range hood motor, n is the motor speed, and A, B, C, and D are coefficients.

[0015] Through experiments, the specific values ​​of four coefficients (A, B, C, and D) corresponding to the target air volume of each speed setting of the exhaust fan were calculated and stored in the MCU chip of the range hood. The speed of the exhaust fan was then controlled through the following steps:

[0016] Step 1: Input the target air volume setting value and output power P1 according to 0Pa back pressure;

[0017] Step 2: After the exhaust fan motor reaches a stable operating power of P1, the actual operating speed n of the exhaust fan motor is calculated in real time by collecting the current curve of the exhaust fan motor.

[0018] Step 3: Using the formula

[0019] P = An 3 +Bn 3 +Cn+D

[0020] Calculate the power P2 corresponding to the current speed of the exhaust fan motor. If P2 is greater than P1, increase P1; if P2 is less than P1, decrease P1.

[0021] Step 4: Output the adjusted P1 value to the motor of the smoke exhaust fan to obtain the new speed n of the smoke exhaust fan motor;

[0022] Step 5: Continue to repeat steps 3 and 4 until the motor of the exhaust fan operates in a state where the difference between P1 and P2 is less than a certain range.

[0023] Optionally, in step 3, P1 increases or decreases by 1-5 watts each time; in step S5, when the difference between P1 and P2 is less than 0.5-2 watts, the air volume of the exhaust fan reaches the set value of the target air volume.

[0024] The range hood provided by this invention can generate an air curtain without the need for an additional independent air curtain fan. Furthermore, the air curtain speed can be controlled in multiple stages by adjusting the rotation speed of the exhaust fan according to the back pressure, making the air curtain speed control more suitable for actual use and improving the effectiveness of the air curtain. Other advantages of this invention are described in the following description. Attached Figure Description

[0025] Figure 1 This is a perspective view of a range hood according to an embodiment of the present invention;

[0026] Figure 2 This is a front view of the range hood according to an embodiment of the present invention;

[0027] Figure 3 yes Figure 2 Sectional view along axis AA;

[0028] Figure 4 yes Figure 2 BB-direction sectional view;

[0029] Figure 5 This is a perspective view of a range hood with its enclosure panel removed according to an embodiment of the present invention;

[0030] Figure 6 This is a perspective view of a range hood with its enclosure removed, according to another embodiment of the present invention.

[0031] Figure 7 This is an exploded view of an air curtain assembly according to an embodiment of the present invention;

[0032] Figure 8 This is an exploded view of an air curtain assembly according to another embodiment of the present invention;

[0033] Figure 9 This is a top view of the air curtain assembly according to an embodiment of the present invention;

[0034] Figure 10 When Figure 9 yes Figure 7 When the air curtain assembly is shown Figure 7 CC-direction cross-section;

[0035] Figure 11 When Figure 9 yes Figure 8 When the air curtain assembly is shown Figure 7 CC-direction cross-section;

[0036] Figure 12 This is a perspective view of a bypass ventilation assembly according to an embodiment of the present invention;

[0037] Figure 13 This is a perspective view of a bypass ventilation assembly according to another embodiment of the present invention;

[0038] Figure 14 This is a perspective view of a bypass ventilation assembly according to another embodiment of the present invention;

[0039] Figure 15 This is a cross-sectional view of a bypass ventilation duct section of a bypass ventilation assembly according to an embodiment of the present invention.

[0040] Figure 16 This is a cross-sectional view of a bypass ventilation duct section of a bypass ventilation assembly according to another embodiment of the present invention.

[0041] Figure 17 This is a PQ curve diagram of the range hood at the medium setting in an embodiment of the present invention;

[0042] Figure 18 This is a PQ curve diagram of the range hood at high speed in an embodiment of the present invention;

[0043] Figure 19 This is the PQ curve of the range hood in the stir-fry mode in this embodiment of the invention.

[0044] Reference numerals: 1. Air curtain assembly; 11. Air curtain top cover; 111. Inlet; 112. Inlet pipe; 12. Air curtain bottom cover; 121. Air outlet; 122. Clip; 13. Vertical air guide component; 14. Press-fit air outlet component; 141. Air guide outlet;

[0045] 2. Range hood housing; 21. Air intake; 22. Air guide vent; 23. Receptacle cavity;

[0046] 3. Bypass ventilation assembly; 31. Bypass ventilation duct section; 311. Connection port; 312. Pipe connection structure; 313. External inlet pipe; 314. Internal inlet pipe; 315. Air intake structure; 32. Check valve; 33. Second oil fume separation device; 34. Slender duct; 35. Multi-port connector;

[0047] 4. Left baffle; 5. Right baffle; 6. PM2.5 detection module; 7. Enclosure; 8. Smoke exhaust fan. Detailed implementation method:

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0050] Example 1

[0051] This embodiment provides a range hood, such as... Figure 1-6As shown, the system includes a smoke hood housing 2, an air curtain assembly 1, a bypass ventilation assembly 3, and a surrounding panel 7. The smoke hood housing 2 is equipped with an air intake 21, an exhaust vent 22, and a guide vent 22. The air intake vent 21 and the exhaust vent form a smoke exhaust duct, within which an exhaust fan 8 is installed. The surrounding panel 7 partially covers the smoke exhaust duct, serving a decorative purpose. Furthermore, a gap exists between the surrounding panel 7 and the wall of the smoke exhaust duct, allowing the slender pipe 34 of the bypass ventilation assembly 3 to pass through. Therefore, the surrounding panel 7 also protects the slender pipe 34. The air intake vent 21 is elongated, horizontally positioned, and extends in the left-right direction; that is, the length direction of the air intake vent 21 is the left-right direction. The guide vent 22 is also elongated and positioned parallel to the air intake vent 21. The air curtain is blown out from the air guide vent 22. The air guide vent 22 should be set in front of the air intake vent 21. This setting can separate people and oil fumes, effectively reduce the escape of oil fumes, and effectively prevent people from inhaling too much oil fumes.

[0052] In this embodiment, two air guide vents 22 are provided, one on the left and one on the right. The air curtain blown out by the air guide vent 22 on the left is called the left air curtain, and the air curtain blown out by the air guide vent 22 on the right is called the right air curtain. There can also be one, three, or even more air guide vents 22. A left baffle 4 and a right baffle 5 are respectively provided on the left and right sides of the range hood housing 2. The air guide vent 22 is located between the left baffle 4 and the right baffle 5. The left baffle 4 and the right baffle 5 serve two purposes: first, to prevent oil fumes from escaping from the left and right sides of the range hood; and second, to prevent the air curtain air at the left end of the left air curtain and the air curtain air at the right end of the right air curtain from escaping from the left and right sides of the range hood and from being sucked away by the air intake vent 21.

[0053] The range hood housing 2 contains a cavity 23. Ventilation holes are provided on the upper wall of the cavity 23, allowing it to connect to the atmosphere. A PM2.5 detection module 6 is installed within the cavity 23. This module 6, equipped with a fan, draws in outside air through the ventilation holes. The PM2.5 detection module 6 detects the PM2.5 level in the inhaled air. When the PM2.5 level exceeds a set value, it sends a signal to the range hood's MCU chip. Upon receiving this signal, the MCU chip adjusts the speed of the exhaust fan 8. This makes the range hood more intelligent. Its applications are numerous. For example, when cooking, a person's hands are sometimes covered in grease, making it inconvenient to manually adjust the exhaust fan 8. When the exhaust fan 8 is set too low, causing excessive oil fumes to escape or overflow, these escaped fumes will be detected by the PM2.5 detection module 6. After the PM2.5 detection module 6 sends a signal to the MCU chip, the MCU chip automatically controls the exhaust fan 8 to be set higher. Therefore, the inclusion of the PM2.5 detection module 6 enables this range hood to automatically detect whether the PM2.5 content in the outside air exceeds the standard, and automatically adjust the exhaust fan 8 to a higher setting when the PM2.5 content exceeds the standard, effectively improving the practicality, intelligence, and environmental friendliness of this range hood.

[0054] like Figure 7-11 As shown, the air curtain assembly 1 includes an air curtain housing and a guide member. The air curtain housing includes an upper air curtain cover 11 and a lower air curtain cover 12, and the guide member is disposed between the upper air curtain cover 11 and the lower air curtain cover 12. The upper air curtain cover 11 is provided with an inlet 111 for introducing part of the smoke discharged by the range hood exhaust fan 8. The lower air curtain cover 12 has a narrow air outlet 121 for forming an air curtain with a downward component. The guide member ensures that the air curtain blows straight along its guiding direction, rather than in a turbulent manner.

[0055] The upper cover 11 and the lower cover 12 of the air curtain are detachably connected, facilitating the cleaning and replacement of the upper cover 11, the lower cover 12, and the guide components. There are many ways to achieve this detachable connection, including but not limited to snap-fit ​​connections, screw connections, or a combination of snap-fit ​​and screw connections. For example, if the upper cover 11 and the lower cover 12 are connected by snap-fit, snap-fit ​​122 can be provided on the lower cover 12, and corresponding slots can be provided on the upper cover 11. Alternatively, a snap-fit ​​structure can be provided on the upper cover 11, and a slot structure on the lower cover 12. The connection between the upper cover 11 and the lower cover 12 of the air curtain should be sealed. Therefore, a sealing connection means is formed between the upper cover 11 and the lower cover 12 of the air curtain. The sealing connection means can also have various structural forms, such as a sponge layer that is compressed and deformed, a receiving groove provided on the connection surface between the upper cover 11 and the lower cover 12 of the air curtain, and a deformable sealing ring or sealing gasket provided in the receiving groove.

[0056] The air curtain cover 11 has a convex cover body, which forms a pressure stabilizing cavity with the guide member. This pressure stabilizing cavity is connected to the inlet 111, which is located in the middle of the pressure stabilizing cavity. The convex cover body forms an inner cavity surface that expands to the left and right with the inlet 111 as the center, allowing the flue gas introduced through the inlet 111 to diffuse more quickly and evenly throughout the pressure stabilizing cavity, resulting in a more uniform air curtain. The angle of this inner cavity surface is between 120° and 160°, for example, it can be 120°, 123°, 130°, 144°, 152°, 160°, etc. An inlet pipe 112 is provided at the inlet 111, which communicates with the pressure stabilizing cavity. The inlet pipe 112 forms a downward angle, with an angle range of 0°-90°, facilitating the connection of the air curtain assembly 1 to the pipeline.

[0057] There are various structural forms of guide components, one of which is as follows: Figure 7 , Figure 9 and Figure 10 As shown, the guide includes a vertical air guiding component 13 and a pressing air outlet component 14, which are arranged one above the other. The vertical air guiding component 13 can be located below the pressing air outlet component 14, such as... Figure 7As shown; it can also be located above the press-fit air outlet component 14. To ensure the air curtain blows straight along its guiding direction rather than in a turbulent manner, the vertical air guide component 13 needs a certain height, or thickness, and cannot be too high or too thick. The height of the vertical air guide component 13 is between 1.5-18mm, specifically 1.5mm, 3.2mm, 6.3mm, 13mm, 15.7mm, 18mm, etc. The vertical air guide component 13 has a hexagonal honeycomb guiding structure and can be made of plastic or metal. The press-fit air outlet component 14 has a narrow, elongated air outlet 141, which corresponds to the air outlet 121 of the lower cover 12 of the air curtain. The press-fit air outlet component 14 has a thin-walled plate surface with a certain degree of elasticity, providing an elastic pressing function.

[0058] Another structure of the guide is as follows Figure 8 , Figure 9 and Figure 11 As shown, the guide component consists of only one vertical air guiding element 13, and it is integrally formed with the lower cover 12 of the air curtain. The guide component has a rectangular grid-shaped structure and can be made of plastic or metal. The height of the guide component is between 1.5-18mm, specifically 1.5mm, 4.4mm, 7.5mm, 12.6mm, 16.4mm, 18mm, etc.

[0059] The two structural forms of the guide component each have their advantages and disadvantages. The first structural form makes the guide component easy to disassemble, clean, and replace, but workers are prone to omissions during assembly, leading to substandard product quality. The second structural form avoids omissions, but is not as convenient for disassembly, cleaning, and replacement. In addition, the guide component also has other structural forms, such as one with two components: a vertical air guiding component 13 and a press-fit air outlet component 14, both integrally formed with the lower cover 12 of the air curtain, etc., which will not be listed here.

[0060] like Figure 5 and Figure 6 As shown, the air curtain assembly 1 is disposed in the receiving cavity 23 of the range hood housing 2. The receiving cavity 23 also houses the PM2.5 detection module 6, circuit boards, and other electrical components and circuit structures. The air curtain assembly 1 introduces purified flue gas. Even after purification, it can still contaminate the electrical components and circuit structures in the receiving cavity 23. Therefore, it is necessary to provide a sealing connection between the lower cover 12 of the air curtain and the range hood housing 2, such as a pressable and deformable sealing ring. This prevents the air containing oil fumes introduced by the air curtain assembly 1 from entering the receiving cavity 23 of the range hood housing 2 through the air outlet 121 of the lower cover 12 of the air curtain, thus avoiding contamination of the electrical components and circuit structures in the receiving cavity 23.

[0061] The fumes introduced by the air curtain assembly 1 are discharged through the air outlet 121 of the lower cover 12 of the air curtain and the guide air outlet 22 of the range hood housing, forming an air curtain. The direction of the air curtain is not required to be vertically downward; it can be appropriately tilted forward or backward, but there must be a downward component. The principle is that the exhaust air from the guide air outlet 22, i.e., the air curtain, must be able to be drawn into the air intake 21 and discharged by the exhaust fan 8.

[0062] like Figure 12-16 As shown, the bypass ventilation assembly 3 includes a bypass ventilation duct section 31, a check valve 32, a second oil fume separation device 33, and a slender duct 34. In some embodiments, it also includes a multi-port connector 35. The second oil fume separation device 33 and the check valve 32 are disposed on the bypass ventilation duct section 31.

[0063] like Figure 3 , Figure 5 , Figure 6 and Figure 12 As shown, one end of the bypass ventilation duct section 31 is connected to the exhaust port of the exhaust fan 8, and the other end is equipped with a connecting pipe structure 312. The connecting pipe structure 312 includes an inner lining pipe section and a snap-fit ​​groove section. The connecting pipe structure 312 is used to connect the exhaust pipe, which is sleeved on the inner lining pipe section. The exhaust pipe has a snap-fit ​​or snap-fit ​​structure, which can snap onto the snap-fit ​​groove section of the connecting pipe structure 312. The bypass ventilation duct section 31 is part of the exhaust duct. The flue gas discharged from the exhaust fan 8 enters the exhaust pipe after passing through the bypass ventilation duct section 31. Therefore, the bypass ventilation duct section 31 is located downstream of the exhaust fan 8 and its interior is a positive pressure zone.

[0064] like Figure 5 , Figure 6 , Figure 12 , Figure 15 and Figure 16 As shown, a connection port 311 is provided on the bypass ventilation duct section 31, and an external inlet pipe 313 is provided on the bypass ventilation duct section 31 outside the connection port 311. The external inlet pipe 313 can be integrally formed with the bypass ventilation duct section 31 or it can be a separate structure. The external inlet pipe 313 is connected to the air curtain assembly 1 through a slender pipe 34. Since the inside of the bypass ventilation duct section 31 is a positive pressure zone, the flue gas passing through it can partially enter the air curtain assembly 1 through the slender pipe 34, and be discharged through the air outlet 121 of the lower cover of the air curtain 12 and the guide air outlet 22 of the smoke machine housing, forming an air curtain.

[0065] The bypass ventilation component 3 has several structural forms, the first of which is as follows: Figure 5 , Figure 12 and Figure 15As shown, the check valve 32 is located downstream of the second oil fume separation device 33. The connection port 311 is located between the second oil fume separation device 33 and the check valve 32, and there are two connection ports 311. Each connection port 311 has an external inlet pipe 313 on its outer side. Each external inlet pipe 313 is connected to an air curtain assembly 1 via a slender pipe 34. The check valve 32, located downstream of the second oil fume separation device 33, protects the second oil fume separation device 33 from the influence of external air duct pollutants. Simultaneously, the check valve 32 also prevents back pressure from the external air duct from causing exhaust air to the guide air vent 22, which could pollute the kitchen. The angle between the external inlet pipe 313 and the horizontal plane is in the range of 20°-80°, specifically 20°, 45°, 60°, 80°, etc. At the same time, the connection port 311 forms a constriction structure with the external inlet pipe 313, so that the oil fumes in the bypass ventilation pipe section 31 can enter the external inlet pipe 313 through the connection port 311, and then enter the air curtain assembly 1 through the slender pipe 34.

[0066] The second structure of the bypass ventilation component 3 is as follows Figure 6 , Figure 13 and Figure 15 As shown, the check valve 32 is located downstream of the second oil fume separation device 33. The connection port 311 is located between the second oil fume separation device 33 and the check valve 32, but only one connection port 311 is provided. An external inlet pipe 313 is provided on the outside of this connection port 311. This external inlet pipe 313 is connected to a multi-way connector 35 via a slender pipe 34. Here, the multi-way connector 35 is a three-way structure; it can also be a four-way connector, etc. The number of ends of the multi-way connector 35 should be one more than the number of air curtain components 1, but the number of ends of the multi-way connector 35 should not be excessive. The other two ends of this multi-way connector 35 are each connected to an air curtain component 1 via a slender pipe 34.

[0067] The third structure of the bypass ventilation component 3 is as follows Figure 14 As shown, the difference between it and the second structure of the bypass ventilation component 3 is that the check valve 32 is not located downstream of the second oil fume separation device 33, but upstream of the second oil fume separation device 33. This can reduce the impact of pollution from the second oil fume separation device 33 on the internal air duct section, and make the second oil fume separation device 33 easy to disassemble, clean and maintain.

[0068] The fourth structure of the bypass ventilation component 3 is as follows Figure 16As shown, an inner inlet pipe 314 and an outer inlet pipe 313 are respectively provided on the inner and outer sides of the connection port 311. The end of the inner inlet pipe 314 away from the connection port 311 is provided with a downward-opening air-guiding structure 315. The air-guiding structure 315 can be an inclined shell-shaped or bowl-shaped structure. The air-guiding structure 315 can increase the air volume passing through the connection port 311, forming a larger air curtain. This structure also eliminates the need for the outer inlet pipe 313 to be inclined upward.

[0069] The slender duct 34 is made of transparent flexible tubing with a diameter ranging from 10-20mm, specifically 10mm, 15mm, 18mm, 20mm, etc., and a length between 25-80 times its diameter. The transparent flexible tubing passes through the gap or cavity between the wall of the positive pressure zone of the exhaust duct and the surrounding panel 27. Using transparent flexible tubing offers the following advantages: firstly, it facilitates observation of whether the interior requires cleaning; secondly, the fluctuating oil fume air introduced by the air curtain assembly 1 is reduced by the transparent flexible tubing, making the air curtain more stable.

[0070] Since the air curtain assembly 1 introduces the fumes discharged by the exhaust fan 8, the fumes entering the air curtain assembly must be purified. This range hood includes at least two purification devices. The exhaust fan 8 is the first fume separation device. When the blades of the exhaust fan 8 rotate at high speed, the rotating blades rub against the fumes, causing oil droplets to condense on the blades and be thrown onto the inner wall of the volute, flowing from the oil leakage hole at the bottom of the volute into the oil collection tank or oil cup. The second fume separation device 33 is installed on the bypass ventilation duct section 31 and includes a discharge electrode and an oil collection electrode. The oil collection electrode adopts a membrane structure or a plate structure. The purification principle of the second fume separation device 33 is similar to that of electrostatic dust removal. Particulate matter in the fumes becomes negatively charged after entering the high-voltage electric field generated by the discharge electrode and is adsorbed by the positively charged oil collection electrode. After being purified by the first and second fume separation devices 33, the PM2.5 purification rate can reach over 98%.

[0071] The working principle of this invention: The air curtain assembly 1 of this invention generates an air curtain by introducing purified oil fumes discharged by the exhaust fan 8 through the bypass ventilation assembly 3. This eliminates the need for a separate, independently controlled air curtain fan. This not only simplifies the structure of the air curtain assembly 1 and the circuitry of the range hood, but also saves on equipment costs and energy consumption.

[0072] In actual use, when the back pressure of a range hood is low, the exhaust of fumes is smooth, requiring little or no air curtain. However, as the back pressure increases, exhaust becomes more difficult. During operation, the air curtain assembly 1 is connected to the common flue. As the back pressure within the common flue increases, the air curtain speeds up accordingly. This faster air curtain effectively blocks and presses down the escaping fumes, allowing the exhaust fan 8 to draw them away.

[0073] Example 2

[0074] This embodiment provides a control method for a range hood. This control method controls the exhaust fan 8 based on back pressure, which is also the control of the air curtain. Back pressure detection is existing technology, and many types of range hoods have back pressure detection modules and functions, so it will not be described further here.

[0075] Traditional range hoods use a constant power and / or constant speed design, meaning that at the same speed setting, the exhaust fan motor operates at a constant power or constant speed. Currently, all range hood manufacturers advertise large exhaust volumes, ranging from 16 cubic meters per minute to 20, 24, or even 26 cubic meters per minute. While large exhaust volumes barely meet national standards for space ventilation, without proper airflow organization, even large volumes cannot effectively reduce oil fume pollution or control airflow direction at the mouth and nose. Furthermore, they consume more electricity, resulting in lower social benefits. In actual use, the exhaust performance of a range hood is affected by the air pressure in the shared exhaust duct. This air pressure is called back pressure. When the back pressure is low, the range hood only needs a small power to achieve a high airflow to meet the exhaust requirements; when the back pressure is high, the range hood needs to increase its power to maintain the airflow. This invention designs a constant airflow algorithm to address the actual usage of range hoods.

[0076] In this embodiment, the range hood has three speed settings: medium, high, and high-heat. With airflow Q as the horizontal axis and back pressure P as the vertical axis, PQ curves were designed for the three speed settings. The PQ curves for the medium, high, and high-heat settings are shown below. Figure 17 , Figure 18 and Figure 19 As shown.

[0077] At medium speed, with a back pressure of 0-35Pa, the airflow is 10.5m³ / h. 3 / min; under a back pressure of 35-250Pa, the air volume is 10.5m³ / min. 3 / min; under a back pressure of 250-300Pa, the air volume drops back to 10.5m³ / min. 3 / min.

[0078] At the high setting, with a back pressure of 0-35Pa, the airflow is 11.5m³ / h. 3 / min; under a back pressure of 35-250Pa, the air volume is 12m³ / min. 3 / min; under a back pressure of 250-300Pa, the air volume drops back to 11.5m³ / min. 3 / min.

[0079] When in the stir-fry mode, the airflow is 13m³ / h under a back pressure of 0-35Pa. 3 / min; under a back pressure of 35-250Pa, the air volume is 13.5m³ / min. 3 / min; Under a back pressure of 250-300Pa, the air volume drops back to 13m³ / min. 3 / min.

[0080] The design concept of the PQ curves for the three levels is the same, which are mainly divided into three segments: 0-35Pa: low back pressure and low air volume area, using constant air volume algorithm control; 35-250Pa: medium and high back pressure and large air volume area, using constant air volume algorithm control; and above 250Pa, high back pressure area, switching from constant air volume algorithm control to constant power control.

[0081] In addition to having three speed settings, range hoods can also have only two speed settings, or even four or more speed settings, depending on the actual product requirements.

[0082] The constant air volume algorithm is designed based on its underlying physical principles. According to the analysis of the physical model of the fan, at the same air volume, the relationship between the motor power P and the speed n satisfies the following formula:

[0083] P = An 3 +Bn 3 +Cn+D

[0084] In the formula, P represents the power of the exhaust fan motor, n represents the motor speed, and A, B, C, and D are coefficients. Different air volumes correspond to different sets of coefficients. By measuring the parameters of the range hood system, data such as air volume, speed, and power are obtained for each air volume setting under a back pressure of 0-250Pa. By calculating these corresponding coefficients, the relationship between power P and fan speed n can be obtained, thereby achieving the goal of constant air volume control.

[0085] Specifically, experiments were conducted using a prototype range hood to calculate the specific values ​​of four coefficients (A, B, C, and D) corresponding to the target airflow at each speed setting of the exhaust fan 8. These values ​​were then stored in the range hood's MCU chip. The speed of the exhaust fan 8 was then controlled through the following steps:

[0086] Step 1: Input the target air volume setting value and output power P1 according to 0Pa back pressure;

[0087] Step 2: After the motor of the exhaust fan 8 reaches the power P1 in stable operation, the actual operating speed n of the exhaust fan 8 motor is calculated in real time by collecting the current curve of the exhaust fan 8 motor.

[0088] Step 3: Using the formula

[0089] P = An 3 +Bn 3 +Cn+D

[0090] Calculate the power P2 corresponding to the current speed of the exhaust fan 8 motor. If P2 is greater than P1, increase P1 by 1-5 watts, specifically 1 watt, 2 watts, 3.5 watts, 5 watts, etc.; if P2 is less than P1, decrease P1 by 1-5 watts, specifically 1 watt, 2 watts, 3.5 watts, 5 watts, etc.

[0091] Step 4: Output the adjusted P1 value to the motor of the smoke exhaust fan 8 to obtain the new speed n of the motor of the smoke exhaust fan 8;

[0092] Step 5: Continuously repeat steps 3 and 4 until the motor of the exhaust fan 8 operates at a power difference of less than 0.5-2 watts between P1 and P2. This is a continuous feedback operation process, which remains dynamic. Therefore, the operation of the exhaust fan 8 does not strictly follow the PQ curve, but constantly fluctuates up and down based on the PQ curve as a standard.

[0093] As described above, the control of the exhaust fan 8 is divided into target airflow control and target power control, which we refer to as the target airflow control unit and the target power control unit, or the target airflow control segment and the target power control segment. The target power control unit and the target airflow control unit switch within a certain back pressure range. In this embodiment, the switching is based on a back pressure of 250 Pa. However, this switching back pressure value is not required to be exactly 250 Pa; it can be within the range of 150-450 Pa. As shown in the PQ curve, the back pressure corresponding to the target power control unit is higher than the back pressure corresponding to the target airflow control unit.

[0094] In the target air volume control unit, the speed of the exhaust fan 8 is controlled to ensure that the exhaust fan 8 operates at a relatively stable air volume at the corresponding operating power under different back pressures. Relatively stable air volume means that different target exhaust volumes are used depending on the speed setting of the exhaust fan 8; the higher the speed setting of the exhaust fan 8, the higher the target air volume is used, and the actual exhaust volume generated by the exhaust fan 8 is within ±15% of the target air volume. In this embodiment, the back pressure range corresponding to the target air volume control unit is 0-250 Pa. When the back pressure value is switched to 300 Pa, the pressure range corresponding to the target air volume control unit is 0-300 Pa.

[0095] In the target power control unit, the higher the speed of the exhaust fan 8, the higher the target power. The target power control unit controls the speed of the exhaust fan 8 to ensure it operates at a relatively stable power level for the corresponding airflow volume under different back pressures. Relatively stable power means the operating power is within ±8% of the actual constant power operating range.

[0096] Since the air curtain assembly 1 of the present invention generates an air curtain by introducing part of the exhaust air from the smoke exhaust fan 8, it can be said that the control of the air curtain speed in the present invention is also achieved by controlling the smoke exhaust fan 8. Specifically, it is achieved by controlling the rotational speed of the smoke exhaust fan 8 according to the back pressure. Thus, it can be seen that the control of the air curtain speed in the present invention is also carried out in multiple stages.

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A range hood comprising an exhaust fan, characterized in that: further comprising a wind curtain module and a wind curtain air control module, the wind curtain module introduces part of the exhaust gas discharged by the exhaust fan to form a wind curtain with a downward component, the wind curtain air control module controls the wind curtain air speed by adjusting the rotation speed of the exhaust fan according to the back pressure, and forms a multi-stage control; the multi-stage control includes a constant air volume stage control that makes the exhaust fan operate at a target air volume by iterative power adjustment; the constant air volume stage control specifically includes: step S1, according to the target air volume set value, output the initial power P1 to the motor of the exhaust fan under zero back pressure, and during the constant air volume stage control, the power-speed of the motor of the exhaust fan satisfies the relationship P=An3+Bn2+Cn+D; step S2, after the motor operates stably at the power P1, the actual speed n of the motor is collected in real time; step S3, the actual speed n is substituted into the power-speed relationship P=An3+Bn2+Cn+D corresponding to the target air volume to calculate the theoretical power P2 under the current speed; step S4, compare the size of P1 and P2: if P2 > P1, increase the power output to the motor by a constant value ΔP; if P2 < P1, decrease the power output to the motor by the constant value ΔP; step S5, repeat steps S2 to S4 until the difference |P1-P2| is less than the preset convergence threshold, at which time the air volume of the exhaust fan reaches the target air volume set value; wherein the coefficients A, B, C, and D are parameters corresponding only to the target air volume, which are calibrated by experiments on the range hood system, and a set of coefficients corresponding to different target air volume set values. 2.A range hood according to claim 1, characterized in that: the wind curtain module comprises a guide air inlet provided on the hood shell and a wind curtain assembly provided in the hood shell at the guide air inlet, the wind curtain assembly comprises a wind curtain shell, the wind curtain shell comprises a detachable wind curtain upper cover and a wind curtain lower cover, the wind curtain upper cover is provided with an inlet, and part of the exhaust gas discharged by the exhaust fan is introduced through the inlet; the wind curtain lower cover has an air outlet, and a guide member is arranged between the wind curtain upper cover and the wind curtain lower cover; the air discharged from the air outlet of the wind curtain assembly is discharged through the guide air inlet to form a wind curtain air with a downward component. 3.A range hood according to claim 2, characterized in that: the wind curtain upper cover has a convex cover body, a pressure stabilizing cavity is formed between the convex cover body and the guide member, the pressure stabilizing cavity communicates with the inlet, the inlet is arranged in the middle of the pressure stabilizing cavity, the convex cover body forms an inner cavity surface that expands to the left and right with the inlet as the center, the angle range of the inner cavity surface is 120°-160°, and an inlet pipe that communicates with the pressure stabilizing cavity through the inlet is arranged at the inlet, the inlet pipe forms a downward angle with an angle range of 0°-90°. 4.A range hood according to claim 2, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The air curtain module further comprises a bypass air assembly, the bypass air assembly comprises a bypass air pipe section, one end of the bypass air pipe section is connected with an exhaust port of the exhaust fan, the other end is provided with a connecting pipe structure, the connecting pipe structure is used for connecting an exhaust pipe, the bypass air pipe section is provided with a connecting port and a non-return valve, the connecting port is connected with an inlet provided on the air curtain upper cover through an elongated pipe.

5. The extractor hood according to claim 1, characterized in that: The air curtain air control module comprises a target air volume control unit and a target power control unit; in the target air volume control unit, the rotational speed of the exhaust fan is controlled, so that the exhaust fan operates in a corresponding operating state with relatively stable air supply volume corresponding to different back pressures; In the target power control unit, the rotational speed of the exhaust fan is controlled, so that the exhaust fan operates in a corresponding operating state with relatively stable operating power corresponding to different air supply volumes.

6. The extractor hood according to claim 5, characterized in that: The target power control unit and the target air volume control unit are switched within a certain back pressure range, the back pressure range is 150-450 Pa; wherein the back pressure corresponding to the target power control unit is higher than the back pressure corresponding to the target air volume control unit.

7. The extractor hood according to claim 5, characterized in that: In the target air volume control unit, the corresponding back pressure range is 0-250 Pa; the relatively stable air supply volume means that different target air volumes are adopted according to different gears of the exhaust fan, and the higher the gear of the exhaust fan, the higher the target air volume adopted, and the actual air supply volume generated by the exhaust fan is within the range of ± 15% of the target air volume.

8. The extractor hood according to claim 5, characterized in that: In the target power control unit, the higher the gear of the exhaust fan, the higher the target power adopted; the relatively stable operating power means that the operating power is within the range of ± 8% of the actual constant power operating state.

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