Range hood and cleaning reminding method thereof

Abstract

The application discloses an extractor hood and a cleaning reminding method thereof. The extractor hood comprises a centrifugal fan, the centrifugal fan comprises a volute and an impeller arranged in the volute, the volute comprises a ring wall, an air outlet and a volute tongue formed on the ring wall; the extractor hood further comprises a pressure sensor for detecting the pressure of the centrifugal fan to determine whether the centrifugal fan needs cleaning; the pressure sensor is arranged on the ring wall of the volute near the volute tongue, and the pressure sensor is located on the side of the volute tongue away from the air outlet. Compared with the prior art, the application has the advantages that: the pressure sensor is arranged adjacent to the volute tongue, the gap is the smallest, the pressure pulsation is the largest, and the pressure change is the most sensitive, so that the sensitivity of monitoring can be improved, the surface of the volute tongue is avoided to be arranged in the straight surface of the oil fume flow, the pollution of the oil fume and the interference of the airflow impact are avoided, and the detection precision is improved.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to a range hood and a cleaning reminder method for the range hood. Background Technology

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. They operate on the principles of fluid dynamics, using a centrifugal fan inside to draw in cooking fumes and a filter to remove some grease particles. The centrifugal fan consists of a casing, an impeller housed within the casing, and a motor that drives the impeller. As the impeller rotates, a negative pressure is generated at the center of the fan, drawing in the cooking fumes from below. After being accelerated by the fan, the fumes are collected by the casing and guided outwards.

[0003] Range hoods are responsible for filtering over 85% of cooking fumes. Over time, grease accumulates on the casing, fan, and other components. This buildup can lead to rust and damage, and weaken the fan system, resulting in poorer aerodynamic performance (pressure and airflow) and reduced fume extraction. Knowing when to clean a range hood remains a challenge. Currently, the following methods are commonly used:

[0004] 1. Clean the range hood regularly, such as once every two years;

[0005] 2. Clean the range hood based on its usage time, for example, clean it once every 300 hours of fan operation.

[0006] The above methods for cleaning range hoods have the following disadvantages:

[0007] Depending on the cooking method, under light cooking conditions, the inside of the range hood may not be ready for cleaning by the time the time is up. First, cleaning requires a service worker to come and maintain it, which wastes manpower by cleaning in advance. Second, the cleaning requires a strong alkaline detergent, which can corrode the surface of the parts and increase the risk of damage to the parts if cleaned in advance. Under heavy cooking conditions, the grease inside the range hood may have exceeded the cleaning conditions. Waiting for regular or scheduled cleaning may cause functional failures in the machine and cause irreversible damage.

[0008] To address this, Chinese Patent Application No. 202210450445.4 proposes a range hood cleaning reminder system, method, and variable frequency range hood, comprising an oil filter, a fan, and an exhaust assembly connected in sequence. The system obtains first fan operating parameters corresponding to the exhaust setting indicated by the exhaust setting command. These parameters include fan power and fan speed. A pressure sensor detects and calculates the difference between pre-set second fan operating parameters and the first fan operating parameters. When the difference meets a preset reminder threshold, a reminder command is sent to the user interaction module. Upon receiving the reminder command, the user interaction module sends a cleaning reminder to the user for either the oil filter or the exhaust assembly.

[0009] However, the existing range hoods use pressure sensors to detect the pressure of the air valve at the connection between the flue and the common flue to determine whether the fan needs cleaning. But the pressure pulsation at this point is small and the changes are not sensitive enough, so the monitoring sensitivity is lacking and therefore cannot provide timely and accurate reminders.

[0010] Existing technologies also include solutions that place pressure sensors inside the fan, such as a centrifugal fan disclosed in Chinese Patent Application No. 201610704005.1, which includes a volute with a volute tongue, a fan impeller disposed inside the volute, and a motor that drives the fan impeller to rotate. It also includes a pressure sensor and a main controller. The pressure sensor is installed on the volute tongue, and the output end of the pressure sensor is used to connect to the input end of the main controller.

[0011] However, in this type of existing range hood, the pressure sensor is installed on the front of the volute, which is directly exposed to the impact of the airflow. On the one hand, the front of the volute will generate vortices after being impacted by the airflow, and the pressure sensor will have low detection accuracy due to the interference of the airflow. On the other hand, oil stains from the fumes will condense on the sensor surface, and over time the oil stains will thicken, causing the pressure sensor to fail. Summary of the Invention

[0012] The first technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a range hood that improves sensitivity and detection accuracy and reduces pollution.

[0013] The second technical problem to be solved by the present invention is to provide a cleaning reminder method for the above-mentioned range hood.

[0014] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a range hood, including a centrifugal fan, the centrifugal fan including a volute and an impeller disposed in the volute, the volute including an annular wall, an air outlet and a volute tongue formed on the annular wall;

[0015] The range hood also includes a pressure sensor for detecting the pressure of the centrifugal fan to determine whether the centrifugal fan needs cleaning; characterized in that:

[0016] The pressure sensor is located on the annular wall of the volute near the volute tongue, and the pressure sensor is located on the side of the volute tongue away from the air outlet.

[0017] By placing the pressure sensor adjacent to the volute tongue, the pressure pulsation is greatest and the pressure change is most sensitive due to the smallest gap at this location. Placing it here can improve the monitoring sensitivity. Moreover, it avoids placing it on the surface of the volute tongue that is directly facing the oil fume flow, thus avoiding oil fume pollution and airflow impact interference, and improving detection accuracy.

[0018] To further improve detection accuracy and avoid direct impact from oil fume flow, the pressure sensor has a detection surface embedded in the ring wall.

[0019] To further improve detection accuracy and avoid direct impact from oil fume flow, the detection surface of the pressure sensor is an inclined plane, which gradually tilts away from the impeller from the side closer to the volute tongue.

[0020] To further avoid direct impact from the oil fume flow, the absolute velocity slope of the airflow at the blade outlet angle on the connecting line from the center of the impeller to the end of the volute tongue is less than the slope of the detection surface of the pressure sensor.

[0021] To ensure that the oil fume airflow is redirected to the tangential direction of the volute ring wall, the shortest distance between the detection surface of the pressure sensor and the outer edge of the impeller is L1, and L1≥15mm is satisfied.

[0022] To ensure that the pressure change meets the requirements and the detection accuracy is high, the shortest distance between the detection surface of the pressure sensor and the volute tongue is L2, and L2≤30mm.

[0023] To reduce the impact of the oil fume airflow from the impeller on the pressure sensor, the centrifugal fan also includes a motor for driving the impeller to rotate. The impeller includes a wheel for mounting the motor, and the center position of the pressure sensor coincides with the wheel along the axial direction of the impeller.

[0024] The first technical solution adopted by the present invention to solve the second technical problem mentioned above is: a cleaning reminder method for a range hood, characterized by comprising the following steps:

[0025] 1) Set the preset value P max The pressure value P measured at the maximum volute tongue clearance at a certain rotational speed m is... max ;

[0026] 2) Within at least three time periods, based on the preset value P max At the same speed of the centrifugal fan, n+1 pressure values ​​P were collected respectively. n n is a natural number not less than 2, Pn This refers to the pressure value collected by the pressure sensor for the nth time within a certain time period, and it alerts the user that the range hood needs cleaning when the following two conditions are met:

[0027] 2.1) Pressure values ​​P in each time period n The mean is greater than the preset value P max ;

[0028] 2.2) Then calculate using the covariance formula, as follows:

[0029]

[0030] When the ratio of d(P) calculated in any time period to d(P) calculated in an adjacent time period is between 0.95 and 1.05.

[0031] The second technical solution adopted by the present invention to solve the above-mentioned second technical problem is: a cleaning reminder method for a range hood, characterized by comprising the following steps:

[0032] 1) Set the preset value P max The pressure value P measured at the maximum volute tongue clearance at a certain rotational speed m is... max ;

[0033] 2) Within at least three time periods, based on the preset value P max At different centrifugal fan speeds m′, n+1 pressure values ​​P are collected respectively. n ′, where n is a natural number not less than 2, P n ′ represents the pressure value collected by the pressure sensor for the nth time within a certain time period, using similarity conversion. The pressure value P at rotation speed m′ n The pressure value P converted to a rotational speed of m n The system will remind users to clean the range hood when the following two conditions are met:

[0034] 2.1) Pressure values ​​P in each time period n The mean is greater than the preset value P max ;

[0035] 2.2) Then calculate using the covariance formula, as follows:

[0036]

[0037] When the ratio of d(P) calculated in any time period to d(P) calculated in an adjacent time period is between 0.95 and 1.05.

[0038] Preferably, in step 2), a reminder is given by emitting a buzzer sound.

[0039] Compared with existing technologies, the advantages of this invention are as follows: The pressure sensor is positioned adjacent to the volute tongue, where the gap is smallest, pressure pulsation is greatest, and pressure changes are most sensitive. Positioning it here improves monitoring sensitivity and avoids placement on the surface of the volute tongue directly facing the oil fume flow, thus preventing pollution from oil fumes and interference from airflow impact, thereby improving detection accuracy. The detection surface of the pressure sensor is an inclined plane, embedded in the volute ring wall, and is not directly impacted by airflow, resulting in smaller detected values ​​and higher accuracy. The invention further enhances monitoring accuracy by employing the average pressure value at a single point and a sample set similarity method based on the covariance formula, ensuring accurate alerts. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a range hood according to an embodiment of the present invention;

[0041] Figure 2 This is a cross-sectional view of a range hood according to an embodiment of the present invention;

[0042] Figure 3 for Figure 2 A magnified schematic diagram of part I;

[0043] Figure 4 This is a schematic diagram of the profile of the centrifugal fan and pressure sensor of the range hood according to an embodiment of the present invention. Detailed Implementation

[0044] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Since the embodiments disclosed in this invention can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0046] See Figures 1-3A range hood includes a centrifugal fan 1 housed within a fan frame 2. In this embodiment, a top-mounted range hood is shown, with a smoke collection hood 3 positioned below the fan frame 2, through which cooking fumes enter the centrifugal fan 1. Alternatively, the range hood can be of any existing form, such as a side-mounted, low-mounted, or ceiling-mounted type, as long as it includes a centrifugal fan 1 as its power source.

[0047] Centrifugal fan 1 includes a volute 11, an impeller 12 disposed within the volute 11, and a motor (not shown) for driving the impeller 12 to rotate. The volute 11 includes two cover plates (not shown) spaced apart along the axial direction of the centrifugal fan and an annular wall 111 disposed between the two cover plates. The volute 11 also includes an outlet 113 and a volute tongue 112 formed on the annular wall 111. The outlet 113 is formed by the cover plates and the annular wall 111. The volute tongue 112 can be an integral structure with the annular wall 111 or a separate structure. The impeller 12 includes blades 121. The structure of the centrifugal fan 1 described above is the same as that of the prior art and will not be repeated here.

[0048] When the range hood is working, pressure is generated inside the centrifugal fan 1. When grease accumulates on the volute 11, its flow channel narrows. The gap between the volute tongue 112 and the impeller 12 is the smallest gap in the entire centrifugal fan 1; that is, the volute tongue gap is the main factor affecting the pressure of the range hood. See also Figure 2 As shown by the arrow in the diagram, when the centrifugal fan 1 is working, most of the airflow will be discharged from the air outlet 113 along the spiral channel inside the volute 11. Some of the airflow that impacts the volute tongue 112 will also be discharged from the air outlet 113 after hitting the volute tongue 112. Therefore, the volute tongue 112 is the key area for oil accumulation.

[0049] Therefore, in this invention, a pressure sensor 4 is disposed on the annular wall 111 of the volute 11 near the volute tongue 112. The pressure sensor 4 is located on the side of the volute tongue 112 away from the air outlet 113. Since the gap is smallest at this location, the pressure pulsation is largest, and the pressure change is most sensitive, placing it here improves the monitoring sensitivity. The pressure sensor 4 has a detection surface 41, which is embedded within the annular wall 111, ensuring that the airflow does not directly impact the surface of the detection surface 41. The detected value is relatively small, and the accuracy is high, solving the problems of easy contamination and low detection accuracy of sensors mounted on the front of the volute tongue 112 as described in the prior art. The detection surface 41 is also tangent to the airflow.

[0050] See also Figure 3 and Figure 4The outlet velocity of impeller 12 is given by the following formula: C2 = U2 + W2, where: C2 is the absolute velocity of the airflow at the blade outlet angle of impeller 12; U2 is the circumferential velocity at the blade outlet of impeller 12; and W2 is the relative velocity of the airflow at the blade outlet of impeller 12. The detection surface 41 of pressure sensor 4 is an inclined plane, gradually tilting away from impeller 12 from the side closer to volute tongue 112. The slope of the absolute velocity C2 of the airflow at the blade outlet angle on the line L connecting the center O of impeller 12 to volute tongue 112 (here, the line connecting the center of impeller 12 and the endpoint M of the profile of volute tongue 112, the endpoint of the profile being the point closer to pressure sensor 4) should be less than the slope of the detection surface 41 of pressure sensor 4. The abscissa for calculating the slope is... Figure 4 The coordinate axis X shown passes through the center of impeller 12 and is perpendicular to the axis of impeller 12, at which point the air outlet 13 is vertically upward. The airflow flows from the inside of impeller 12 to the outside along the tangent of the blades. To ensure that the airflow can be redirected to the tangent of the annular wall 111 of the volute 11, the shortest distance L1 between the detection surface 41 of pressure sensor 4 and the outer edge of impeller 2 is required to be more than 15mm. If it is too far from the volute tongue 112, the pressure change will be smaller and the detection accuracy will be worse. The shortest distance between the detection surface 41 of pressure sensor 4 and volute tongue 112 is L2, and L2 ≤ 30mm is satisfied.

[0051] To reduce the impact of the airflow from the impeller 12 on the pressure sensor 4, the center of the pressure sensor 4 is aligned with the impeller 12's middle disc (dual-inlet fan) or rear disc (single-inlet fan) disc 122 in the axial direction of the impeller 12. The disc 122 is a structure for mounting to the motor, such as the mounting disc disclosed in Chinese Patent Application No. 202222903543.7, or the aluminum part disclosed in Chinese Patent Application No. 202221768954.3, which is an existing structure of the impeller 12.

[0052] For range hoods with the above-described structure, the cleaning reminder method can be one of the following two methods. Considering that using a single pressure value as the basis for judgment may lead to misjudgment due to environmental factors (changes in flue resistance causing different rotation speeds and resulting in unstable pressure values), the method in this embodiment uses a combination of single pressure value and covariance for judgment.

[0053] The first method, based on centrifugal fan 1 at the same rotational speed, includes the following steps:

[0054] 1) Set the preset value P max Given the varying operating conditions of range hoods and the significant pressure fluctuations at the volute (112), a preset value P needs to be provided. max As a parameter correction, the pressure value P measured at a certain rotational speed m at the maximum volute tongue clearance (i.e., when the centrifugal fan 1 of the range hood is not contaminated) is used. maxTherefore, any pressure value P obtained thereafter satisfies P>P max ;

[0055] 2) Within at least three time periods, based on the preset value P max At the same rotational speed m of centrifugal fan 1, n+1 pressure values ​​P are collected respectively. n n is a natural number not less than 2, P n The pressure value collected by pressure sensor 4 for the nth time within a certain time period, and under the following two conditions, will trigger a buzzer from the range hood's control module to remind the user that the range hood needs cleaning:

[0056] 2.1) Pressure values ​​P in each time period n The mean is greater than the preset value P max This proves that the range hood has met the cleaning conditions, but a single average pressure value cannot determine whether the pressure change is caused by the change in rotation speed.

[0057] 2.2) Then, the value measured at the same rotational speed is determined using the covariance formula. The detected pressure value can be used as the basis for judgment. The formula is as follows:

[0058] The similarity method of the sample set is used to eliminate the interference of the correlation between variables and to clarify the reliability of the data. That is, when d(P) approaches the mean of the sample set; when the ratio of d(P) calculated in any time period to d(P) calculated in adjacent time periods is between 0.95 and 1.05, it means that the mean pressure value of each time period is close and the pressure value is the value measured at the same speed.

[0059] The second method, based on centrifugal fan 1 at different speeds, includes the following steps:

[0060] 1) Set the preset value P max Given the varying operating conditions of range hoods and the significant pressure fluctuations at the volute (112), a preset value P needs to be provided. max As a parameter correction, the pressure value P measured at a certain rotational speed m at the maximum volute tongue clearance (i.e., when the centrifugal fan 1 of the range hood is not contaminated) is used. max Therefore, any pressure value P obtained thereafter satisfies P>P max ;

[0061] 2) Within at least three time periods, based on the preset value P max At different speeds m′ of centrifugal fan 1, n+1 pressure values ​​P are collected respectively. n ′, where n is a natural number not less than 2, P n ′ represents the pressure value collected by pressure sensor 4 for the nth time within a certain time period, using similarity conversion. The pressure P at different rotational speeds m′ n Converted to pressure value P at the same rotational speed (m) n The range hood's control module will emit a buzzer to remind the user that the range hood needs cleaning when the following two conditions are met:

[0062] 2.1) When the pressure value P in each time period n The mean is greater than the preset value P max This proves that the range hood has met the cleaning conditions, but a single average pressure value cannot determine whether the pressure change is caused by the change in rotation speed.

[0063] 2.2) Then, the value measured at the same rotational speed is determined using the covariance formula, as follows:

[0064] The method of using the similarity of sample sets can be used to eliminate the interference of correlation between variables and clarify the reliability of the data. Specifically, when d(P) approaches the mean of the sample set, and when the ratio of d(P) calculated in a certain time period to d(P) calculated in an adjacent time period is between 0.95 and 1.05, it means that the cleaning condition is met.

Claims

1. A range hood, comprising a centrifugal fan (1), the centrifugal fan (1) comprising a volute (11) and an impeller (12) disposed within the volute (11), the volute (11) comprising an annular wall (111), an air outlet (113) and a volute tongue (112) formed on the annular wall (111); The range hood also includes a pressure sensor (4) for detecting the pressure of the centrifugal fan (1) to determine whether the centrifugal fan (1) needs cleaning; characterized in that: The pressure sensor (4) is located on the annular wall (111) of the volute (11) near the volute tongue (112), and the pressure sensor (4) is located on the side of the volute tongue (112) away from the air outlet (113). The pressure sensor (4) has a detection surface (41) embedded in the annular wall (111). The detection surface (41) of the pressure sensor (4) is an inclined surface. The detection surface (41) gradually tilts away from the impeller (12) from the side close to the volute tongue (112) to the side away from the volute tongue (112).

2. The hood according to claim 1, characterized in that: The absolute velocity slope of the airflow at the blade outlet angle on the connecting line (L) from the center (O) of the impeller (12) to the end point (M) of the volute tongue (112) profile is less than the slope of the detection surface (41) of the pressure sensor (4).

3. The range hood according to claim 1, characterized in that: The shortest distance between the detection surface (41) of the pressure sensor (4) and the outer edge of the impeller (12) is: and satisfy .

4. The range hood according to claim 1, characterized in that: The shortest distance between the detection surface (41) of the pressure sensor (4) and the volute (112) is and satisfy .

5. The range hood according to claim 1, characterized in that: The centrifugal fan (1) also includes a motor for driving the impeller (12) to rotate. The impeller (12) includes a wheel disc (122) for mounting the motor. Along the axial direction of the impeller (12), the center position of the pressure sensor (4) coincides with the wheel disc (122).

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