Airflow control system, range hood, control device, and computer program

Abstract

To provide a technique capable of appropriately controlling an airflow according to a situation.SOLUTION: An airflow control system 1 according to the present disclosure includes: a VOC sensor 24; and a control device 22 for controlling an air amount of a ventilation fan 4 for ventilating a room. The control device 22 includes a processing unit 26 that executes: arithmetic processing 26a for obtaining an index i on the basis of the output of the VOC sensor 24; and control processing 26b for controlling the air amount on the basis of the index i. The arithmetic processing 26a includes: processing for obtaining the index i on the basis of a mean value of detected concentrations in a predetermined past period among detected concentrations obtained on the basis of an output of the VOC sensor 24; processing for determining whether or not the index i satisfies a predetermined condition; and processing for resetting the mean value when it is determined that the index i satisfies the predetermined condition.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an airflow control system, a range hood, a control device, and a computer program. [Background technology]

[0002] Patent Document 1 discloses a range hood. This range hood is a ventilation device that has an airflow generator such as a sirocco fan or a turbo fan built in and takes in indoor air through an opening provided in the hood and exhausts it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-115825 A Summary of the Invention [Problem to be solved by the invention]

[0004] The air volume of the range hood is sometimes automatically controlled based on the output of a sensor for detecting the concentration of pollutants in the indoor air. In air volume control based on the output of the above sensor, the stable concentration is calculated based on past detected concentrations, and the air volume is determined based on the difference between the stable concentration and the current detected concentration, or the air volume is determined based on the average value of the detected concentration over a certain period of time in the past. This allows the airflow to be adjusted according to the situation, reducing power consumption and improving usability.

[0005] Here, for example, when controlling the air volume based on the average value of the detected concentration over a certain period of time in the past, even if the current detected concentration suddenly changes due to cooking being started below the range hood or the cooking contents being changed, this may not be reflected in the control of the air volume. More specifically, when cooking is started below the range hood, the current detected concentration rises and the average detected concentration also rises. When the average detected concentration rises, the airflow is controlled to be larger. Thereafter, when cooking is finished, the current detected concentration falls, but the average detected concentration falls slowly with a delay from the current detected concentration. The airflow is controlled to be smaller in accordance with the fall in the average detected concentration. Thus, the airflow is controlled to be smaller with a further delay after cooking is finished.

[0006] In this way, when controlling the air volume based on the average value of the detected concentration over a certain period of time in the past, the difference between the current detected concentration and the average detected concentration becomes large, and a delay occurs before the current detected concentration is reflected in the average concentration, making it impossible to appropriately control the air volume according to the situation. [Means for solving the problem]

[0007] The air volume control system disclosed herein includes a sensor that detects the concentration of a pollutant in indoor air, and a control device that controls the air volume of a ventilation fan that ventilates the room. The control device includes a processing unit that executes a calculation process to determine a concentration index indicating the concentration of the pollutant based on an output of the sensor, and a control process to control the air volume based on the concentration index. The calculation process includes a process to determine the concentration index based on an average value of detected concentrations over a predetermined past period among detected concentrations obtained based on the output of the sensor, a process to determine whether the concentration index satisfies a predetermined condition, and a process to reset the average value when it is determined that the concentration index satisfies the predetermined condition. Effect of the Invention

[0008] According to the present disclosure, the air volume can be appropriately controlled according to the situation. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a partially cutaway side view of a range hood. [Diagram 2]FIG. 2 is a perspective view of the range hood. [Diagram 3] FIG. 3 is a block diagram showing an example of an air volume control system. [Figure 4] FIG. 4 is a flowchart showing an example of a calculation process performed by the processing unit. [Diagram 5] FIG. 5 is a flowchart illustrating an example of a control process performed by the processing unit. [Figure 6] Fig. 6(a) is a graph showing an example of the change over time of the index when only the index is continuously obtained using a VOC sensor, and Fig. 6(b) is a graph showing an example of the change over time of the index when the average value is reset. [Figure 7] FIG. 7 is a graph showing an example of a change in index when cooking work is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First, the contents of the embodiment will be listed and described. [Overview of the embodiment]

[0011] (1) The air volume control system disclosed herein includes a sensor that detects the concentration of a pollutant in indoor air, and a control device that controls the air volume of a ventilation fan that ventilates the room. The control device includes a processing unit that executes a calculation process to determine a concentration index indicating the concentration of the pollutant based on an output of the sensor, and a control process to control the air volume based on the concentration index. The calculation process includes a process to determine the concentration index based on an average value of detected concentrations over a predetermined past period among detected concentrations obtained based on the output of the sensor, a process to determine whether the concentration index satisfies a predetermined condition, and a process to reset the average value when it is determined that the concentration index satisfies the predetermined condition.

[0012] According to the above configuration, by setting predetermined conditions so as to determine whether there is a possibility of an abnormality in the average value, such as the average value of the detected concentration for the past period being higher than necessary, the average value can be reset if it is determined that there is an abnormality in the average value, and the difference between the current detected concentration and the average value of the concentration for the past period represented by the concentration index can be eliminated. As a result, the currently detected concentration can be quickly reflected in the concentration index, and the air volume can be appropriately controlled according to the situation.

[0013] (2) In the air volume control system of (1) above, the control process may include, when the average value is reset, a process of maintaining the control content immediately before the average value was reset for a certain period of time after the average value is reset. Immediately after the average value is reset, the amount of detected concentration data used to calculate the concentration index is small, and the concentration index may not be stable. In this regard, according to the present configuration, the immediately preceding control content is maintained for a certain period of time, so that it is possible to prevent the use of a concentration index from a period that may be unstable.

[0014] (3) In the air volume control system of (1) above, the predetermined condition may include at least a condition for the concentration index and a condition for a predetermined amount of change in the concentration index per unit time. In this case, the condition for resetting the average value can take into account not only the concentration index but also the amount of change in the concentration index, allowing for more precise determination of whether or not an abnormality has occurred in the average value of the detected concentrations over the past period.

[0015] (4) In the air volume control system of (3) above, the predetermined condition may include the concentration index being in one of the following three states: First state: The amount of change in the concentration index per unit time is less than a first threshold value, and the concentration index is less than a first lower limit value or equal to or greater than a first upper limit value. Second state: The amount of change in the concentration index per predetermined unit time is less than a second threshold value that is greater than the first threshold value, and the concentration index is less than a second lower limit value that is less than the first lower limit value or is equal to or greater than a second upper limit value that is greater than the first upper limit value. Third state: The amount of change in the concentration index per predetermined unit time is less than a third threshold value that is greater than the second threshold value, and the concentration index is less than a third lower limit value that is less than the second lower limit value, or is equal to or greater than a third upper limit value that is greater than the second upper limit value.

[0016] In this case, the concentration index and the amount of change in the concentration index in the condition for resetting the average value are restricted in more detail, so that it is possible to more precisely determine whether or not an abnormality has occurred in the average value of the detected concentrations over the past period.

[0017] (5) In addition, in the air volume control system of (4) above, the specified condition may include any one of the three states continuing for a specified duration, and the system can be configured to reset the average value when any one of the three states continues.

[0018] (6) In the air volume control system according to any one of (1) to (5) above, the sensor preferably includes a volatile organic compound sensor.

[0019] (7) Also, from another viewpoint, the present disclosure is a range hood. The range hood includes a ventilation fan that ventilates a room, a sensor that detects a concentration of a pollutant in the air in the room, and a control device that controls an air volume of the ventilation fan. The control device includes a processing unit that executes a calculation process to determine a concentration index indicating the concentration of the pollutant based on an output of the sensor, and a control process to control the air volume based on the concentration index. The calculation process includes a process to determine the concentration index based on an average value of detected concentrations over a predetermined past period among detected concentrations obtained based on the output of the sensor, a process to determine whether the concentration index satisfies a predetermined condition, and a process to reset the average value when it is determined that the concentration index satisfies the predetermined condition.

[0020] (8) From another viewpoint, the present disclosure is a control device for controlling an air volume of a ventilation fan for ventilating a room. The control device includes a processing unit that executes a calculation process for determining a concentration index indicating a concentration of a pollutant based on an output of a sensor that detects the concentration of the pollutant in the air in the room, and a control process for controlling the air volume based on the concentration index. The calculation process includes a process for determining the concentration index based on an average value of detected concentrations over a predetermined past period among detected concentrations obtained based on the output of the sensor, a process for determining whether the concentration index satisfies a predetermined condition, and a process for resetting the average value when it is determined that the concentration index satisfies the predetermined condition.

[0021] (9) From another viewpoint, the present disclosure is a computer program for causing a computer to execute a process for controlling an air volume of a ventilation fan that ventilates a room. This computer program causes the computer to execute a calculation step of determining a concentration index indicating a concentration of a pollutant based on an output of a sensor that detects the concentration of the pollutant in the air in the room, and a control step of controlling the air volume based on the concentration index. The calculation step includes a step of determining the concentration index based on an average value of detected concentrations over a predetermined past period among detected concentrations obtained based on the output of the sensor, a step of determining whether the concentration index satisfies a predetermined condition, and a step of resetting the average value when it is determined that the concentration index satisfies the predetermined condition.

[0022] [Details of the embodiment] Hereinafter, preferred embodiments will be described with reference to the drawings. At least a part of each of the embodiments described below may be combined in any manner.

[0023] [Overall structure of range hood] Fig. 1 is a partially cutaway side view of a range hood 1. Two arrows in Fig. 1 indicate the height direction and depth direction of the range hood 1, respectively. Fig. 2 is a perspective view of the range hood 1. Three arrows in Fig. 2 indicate the height direction, width direction, and depth direction of the range hood 1, respectively. The range hood 1 is a ventilation device including a ventilation unit 10 and an air volume control system 20. The ventilation unit 10 has a function of ventilating the room in which the range hood 1 is installed. The ventilation unit 10 of this embodiment can be installed with its back surface in contact with a wall surface inside a room (wall-mounted type). The ventilation unit 10 may also be mounted on a wall by its side surface. The ventilation unit 10 may also be installed in contact with a ceiling without contacting a wall surface (ceiling-mounted type). The ventilation unit 10 has an air blower box 3 with a built-in ventilation fan 4 that is an airflow generator, a flat box-shaped hood 2 with an open bottom attached to the lower part of the air blower box 3, and a straightening plate 9. The ventilation box 3 is provided between the hood 2 and a ventilation opening (not shown) that communicates between the inside and outside of the room.

[0024] The hood 2 has an inner panel 5. The inner panel 5 has an opening 5A for taking air into the ventilation box 3. A filter 6 is provided in the opening 5A. The periphery of the opening 5A of the inner panel 5 has a surface shape that is horizontal or approximately horizontal when the range hood 1 is installed. The inner panel 5 is formed from a plate material made of a magnetic material, for example, structural steel or the like.

[0025] Air is taken into the blower box 3 by an airflow generated by the ventilation fan 4. The ventilation fan 4 has a fan body 4a and a motor 4b. The fan body 4a is driven to rotate by the motor 4b. The ventilation fan 4 generates an airflow for ventilation by the rotation of the fan body 4a.

[0026] The straightening plate 9 is attached to the rear edge in the depth direction of the hood 2. The straightening plate 9 straightens the flow of air sucked from the opening 5A. The straightening plate 9 has a rectangular plate shape. The current plate 9 is attached to the hood 2 via a hinge 7. The hinge 7 connects the current plate 9 to the hood 2 so that the current plate 9 is rotatable in the up and down direction.

[0027] The current plate 9 has a pair of magnetically attached portions 8. The pair of magnetically attached portions 8 are magnetically attached to the magnetically attached portions 5B at corresponding positions on the inner panel 5. When the magnetically attracted portion 8 is magnetically attracted to the magnetically attracted portion 5B, the current plate 9 is in a closed state. The closed state of the current plate 9 refers to a state in which the current plate 9 is in a position P1 indicated by a solid line in FIG. When the magnetic attraction of the magnetic part 8 to the magnetically attracted part 5B is released, the current plate 9 is in an open state. The open state of the current plate 9 refers to a state in which the current plate 9 is in a position P2 indicated by a dotted line in FIG.

[0028] The ventilation unit 10 draws in the air from the room in which the range hood 1 is installed through the opening 5A by the airflow generated by the ventilation fan 4. At that time, the air passes through the filter 6, and oil, dust, and other substances contained in the air are collected by the filter 6. The air from the room drawn in through the opening 5A is taken into the air blower box 3, passes through the air blower box 3, and is exhausted from the ventilation port. This ventilates the room.

[0029] The air volume control system 20 has a function of controlling the air volume of the ventilation fan 4. As shown in Fig. 1 and Fig. 2, the air volume control system 20 is provided in the hood 2, for example.

[0030] [Air volume control system] FIG. 3 is a block diagram showing an example of the air volume control system 20. 3, the air volume control system 20 includes a control device 22 and a VOC sensor 24. The control device 22 and the VOC sensor 24 are mounted on a single circuit board and provided in the hood 2, for example. The VOC sensor 24 is a sensor that detects the concentration of volatile organic compounds. A detection portion of the VOC sensor 24 is exposed on the underside of the hood 2. The VOC sensor 24 detects the concentration of pollutants (volatile organic compounds) contained in oily smoke, steam, and the like generated by cooking or the like performed below the ventilation unit 10. The VOC sensor 24 is connected to the control device 22. The VOC sensor 24 provides the detected output to the control device 22. The control device 22 is connected to the motor 4b and is capable of giving control commands to the motor 4b.

[0031] The control device 22 is a type of information processing device such as a computer, etc. The control device 22 includes a processing unit 26 and a storage unit 28. The processing unit 26 is, for example, any of various processors suitable for computer control, such as a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), or a field programmable gate array (FPGA).

[0032] The storage unit 28 is, for example, a flash memory, a hard disk, a ROM (Read Only Memory), a RAM (Random Access Memory), or the like. The storage unit 28 stores computer programs and necessary information to be executed by the processing unit 26. The processing unit 26 executes computer programs stored in a computer-readable non-transitory recording medium such as the storage unit 28, thereby realizing various processing functions possessed by the processing unit 26.

[0033] The processing unit 26 has a function of acquiring the detected concentration of VOCs based on the output of the VOC sensor 24. The processing unit 26 also has a function of giving a control command to the motor 4b to control the rotation speed of the motor 4b. The processing unit 26 also has a function of determining whether the motor 4b is in an ON state. The ON state means that the motor 4b is in an operating state due to the application of power, and the OFF state means that the motor 4b is not in an operating state due to the absence of power. The processing unit 26 can control the volume of the airflow generated by the ventilation fan 4 by controlling the rotation speed of the motor 4b.

[0034] The processing unit 26 has a function of executing a calculation process 26a and a control process 26b. The calculation process 26a is a process for determining an index i (concentration index) indicating the concentration of VOCs based on the output of the VOC sensor 24. The control process 26b is a process for controlling the air volume (the rotation speed of the motor 4b) based on the index i.

[0035] [Regarding arithmetic processing and control processing] FIG. 4 is a flowchart showing an example of the calculation process performed by the processing unit 26.

[0036] 4, the processing unit 26 first acquires the detected concentration (step S1 in FIG. 4). The processing unit 26 acquires the detected concentration based on the current output of the VOC sensor 24, and stores it in the storage unit . The processing unit 26 acquires and stores the detected concentration every time the calculation process is repeated. Therefore, the detected concentration is stored in the storage unit 28 as time-series discrete value data.

[0037] Next, the processing unit 26 calculates the index i and the amount of change Δi of the index i (step S2 in FIG. 4). The processing unit 26 obtains an average value of the detected concentration for a predetermined past period. Furthermore, the processing unit 26 obtains an index i based on the average value of the detected concentration for the past period. The index i is a concentration index that expresses the average value of the detected concentration as a relative value. In this embodiment, the predetermined past period is, for example, 2 hours. The processing unit 26 sets the value when the average value of the detected concentration is stable (stable value) as index i=100, and calculates the relative value of the average value of the detected concentration when the stable value is used as a reference, as index i. At this time, the processing unit 26 maps the index i to a value ranging from the lower limit 0 to the upper limit 500.

[0038] The stable value is a value when the average value of the detected concentration has been stable for a long period of time in the past. In other words, the stable value can be said to be the average value of the detected concentration when cooking or the like is not performed below the ventilation unit 10 and almost no VOC generation is observed. In addition, if there is a difference between the current detected concentration and the current stable value, and the current detected concentration has been maintained in a stable state for a longer period than the past period, the processing unit 26 may adjust the current stable value to be closer to the current detected concentration.

[0039] Processing unit 26 calculates index i every time the calculation process is repeated, and stores it in storage unit 28. Therefore, index i is also stored in storage unit 28 as time-series discrete value data, similar to the detected concentration. The processing unit 26 refers to the discrete value data of the index i stored in the storage unit 28 and calculates the amount of change Δi of the index i. The change amount Δi of index i is the change amount of index i per a predetermined unit time. In this embodiment, the predetermined unit time is, for example, 3 minutes. The processing unit 26 obtains the difference between the maximum value and the minimum value of index i within the most recent unit time as the change amount Δi. The unit time of the change amount Δi is preferably set according to the timing when the cooking task changes, for example. In order to determine the change in the cooking task status, about three minutes is generally sufficient, and from this point of view, the unit time of the change amount Δi is set to three minutes.

[0040] After calculating the index i and the amount of change Δi, the processing unit 26 determines whether or not the motor 4b is in the ON state (step S3 in FIG. 4). The motor 4b may be switched between an ON state and an OFF state in conjunction with other surrounding electric devices, or may be switched between an ON state and an OFF state by an externally operable switch. The processing unit 26 performs different processes depending on the state of the motor 4b.

[0041] In step S3 of FIG. 4, when it is determined that the motor 4b is in the ON state, the processing unit 26 proceeds to step S4, and determines whether the index i and the amount of change Δi correspond to any one of the following first state, second state, and third state (step S4 in FIG. 4).

[0042] First state: The change amount Δi is less than the first threshold value Th1, and the index i is less than the first lower limit value iL1 or is equal to or greater than the first upper limit value iU1. Second state: The change amount Δi is less than the second threshold value Th2, and the index i is less than the second lower limit value iL2 or greater than or equal to the second upper limit value iU2. Third state: The change amount Δi is less than the third threshold value Th3, and the index i is less than the third lower limit value iL3 or greater than or equal to the third upper limit value iU3.

[0043] In this embodiment, the first threshold Th1 is 15, the second threshold Th2 is 30, and the third threshold Th3 is 50. In addition, the first lower limit value iL1 is 90, the second lower limit value iL2 is 70, and the third lower limit value iL3 is 50. In addition, the first upper limit value iU1 is 110, the second upper limit value iU2 is 200, and the third upper limit value iU3 is 300.

[0044] When the index i and the amount of change Δi satisfy both the first state and the second state, the processing unit 26 determines that the state of the index i and the amount of change Δi is the first state. When the index i and the amount of change Δi satisfy both the second state and the third state, the processing unit 26 determines that the state of the index i and the amount of change Δi is the second state.

[0045] In step S4 in FIG. 4, when it is determined that the index i and the amount of change Δi do not correspond to any of the first state, the second state, and the third state described below, the processing unit 26 returns to step S1. On the other hand, if it is determined that the index i and the amount of change Δi correspond to any one of the first state, the second state, and the third state described below, the processing unit 26 proceeds to step S5, and determines whether each state has continued for a predetermined duration (step S5 in FIG. 4).

[0046] When the state of the index i and the amount of change Δi is the first state, the predetermined duration is 5 minutes. Note that in this case, it may be limited to the case where either the first or second condition below is satisfied. First condition: Less than 10 seconds or more than 80 minutes have passed since the motor 4b was turned on. Second condition: index i is less than 90

[0047] When the state of the index i and the amount of change Δi is the second state, the predetermined duration is 10 minutes. Note that in this case, it may be limited to the case where either the above-mentioned first condition or the following third condition is satisfied. Third condition: Index i is less than 70

[0048] When the state of the index i and the amount of change Δi is the third state, the predetermined duration is 30 minutes. Note that in this case, it may be limited to the case where either the first condition above or the fourth condition below is satisfied. Fourth condition: Index i is less than 50

[0049] In step S5 in FIG. 4, when it is determined that each state has not continued for the predetermined duration, the processing unit 26 returns to step S1. On the other hand, when it is determined that each state has continued for the predetermined duration, the processing unit 26 proceeds to step S6, resets the average value of the detected concentration for the past period (step S6 in FIG. 4), and returns to step S1. In this case, the processing unit 26 calculates the average value of the detected concentrations using the detected concentrations acquired after resetting the average value of the detected concentrations, and calculates the index i. Therefore, the average value after reset is not affected by the detected concentrations before reset. In step S6, the processing unit 26 may reset the index i. In this case, the processing unit 26 also calculates an average value of the detected concentrations using the detected concentrations acquired after the reset, and calculates a new index i.

[0050] If it is determined in step S3 in FIG. 4 that the motor 4b is not in the ON state, the processing unit 26 proceeds to step S7 (FIG. 4) and determines whether the index i and the change amount Δi correspond to either the first state or the third state (step S7 in FIG. 4).

[0051] In step S7 in FIG. 4, when it is determined that the index i and the amount of change Δi do not correspond to either the first state or the third state, the processing unit 26 returns to step S1. On the other hand, if it is determined that the index i and the amount of change Δi correspond to either the first state or the third state described below, the processing unit 26 proceeds to step S8, and determines whether or not the index i and the amount of change Δi correspond to the first state (step S8 in FIG. 4).

[0052] In step S8 in FIG. 4, when it is determined that the index i and the amount of change Δi correspond to the first state, the processing unit 26 determines whether the first state has continued for 30 seconds and whether 30 hours have passed since the average value of the detected concentration for the previous period was reset (step S9 in FIG. 4).

[0053] In step S9 in FIG. 4, if it is determined that the first state has not continued for 30 seconds or that 30 hours have not elapsed since the average value of the detected concentration in the previous period was reset, the processing unit 26 returns to step S1. On the other hand, if it is determined that the first state continues for 30 seconds and 30 hours have passed since the average value of the detected concentration for the previous period was reset, the processing unit 26 proceeds to step S6, resets the average value of the detected concentration for the previous period (step S6 in Figure 4), and returns to step S1.

[0054] In step S8 in FIG. 4, when it is determined that the index i and the amount of change Δi do not correspond to the first state (correspond to the third state), the processing unit 26 determines whether the third state has continued for five minutes (step S10 in FIG. 4).

[0055] When it is determined in step S10 in FIG. 4 that the third state has not continued for five minutes, the processing unit 26 returns to step S1. On the other hand, when it is determined that the third state has continued for five minutes, the processing unit 26 proceeds to step S6, resets the average value of the detected concentration for the past period (step S6 in FIG. 4), and returns to step S1. In this manner, the processing unit 26 performs the calculation process to obtain the index i.

[0056] FIG. 5 is a flowchart showing an example of the control process performed by the processing unit 26. The processor 26 controls the air volume (the rotation speed of the motor 4b) to one of three levels: "strong", "medium", and "weak" according to the value of the index i. When the air volume is "strong", the rotation speed of the motor 4b is the fastest and the air volume is the largest. When the air volume is "weak", the rotation speed of the motor 4b is the slowest and the air volume is the smallest.

[0057] As shown in FIG. 5, the processing unit 26 first determines whether or not the motor 4b is in an ON state (step S21 in FIG. 5). The processing unit 26 repeats step S21 until it determines that the motor 4b is in the ON state. When it is determined that the motor 4b is in the ON state, the processing unit 26 determines whether or not the average value of the detected concentration in the immediately previous period has been reset (step S22 in FIG. 5). When it is determined that the average value of the detected concentration has been reset, the processing unit 26 maintains the current control content of the motor 4b for a certain period of time (for example, one minute) (step S23 in FIG. 5), and returns to step S21.

[0058] When it is determined that the average value of the detected concentrations has not been reset, the processing unit 26 determines whether the current index i is equal to or greater than 110 (step S24 in FIG. 5). When it is determined in step S24 in FIG. 5 that the index i is not equal to or greater than 110 (is less than 110), the processing unit 26 controls the motor 4b so that the airflow rate becomes "weak" (step S25), and the process returns to step S21.

[0059] When it is determined in step S24 in FIG. 5 that the index i is equal to or greater than 110, the processing unit 26 determines whether or not the index i is equal to or greater than 250 (step S26 in FIG. 5).

[0060] When it is determined in step S26 in FIG. 5 that the index i is not equal to or greater than 250 (is less than 250), the processing unit 26 controls the motor 4b so that the airflow rate becomes "medium" (step S27), and the process returns to step S21. In step S26 in FIG. 5, when it is determined that the index i is equal to or greater than 250, the processing unit 26 controls the motor 4b so that the airflow rate becomes "high" (step S28), and the process returns to step S21. In this way, the processing unit 26 controls the air volume (the rotation speed of the motor 4b) based on the index i.

[0061] The calculation process 26a configured as described above includes a process of determining an index i (concentration index) and an amount of change Δi based on an average value of the detected concentrations over a predetermined past period among the detected concentrations obtained based on the output of the VOC sensor 24 (step S2 in FIG. 4), a process of determining whether or not the index i satisfies predetermined conditions (steps S4-5, S7-10 in FIG. 4), and a process of resetting the average value when it is determined that the index i satisfies the predetermined condition (step S6 in FIG. 4).

[0062] According to this configuration, a predetermined condition is set so that it is possible to determine whether or not there is a possibility that an abnormality has occurred in the average value, such as the average value of the detected concentration over the past period being larger than necessary, and the average value is reset when it is determined that an abnormality has occurred in the average value. Thus, it is possible to eliminate the difference between the currently detected concentration and the average value of the concentration over the past period represented by index i. As a result, the currently detected concentration can be quickly reflected in the index i, and the air volume can be appropriately controlled according to the situation.

[0063] Furthermore, in this embodiment, when the average value is reset, a process is included in which the control content immediately before the average value was reset is maintained for one minute after the average value is reset (steps S22 and S23 in FIG. 5). Immediately after the average value is reset, the amount of detected concentration data used to calculate index i is small, and index i may not be stable. In this regard, according to the present configuration, the immediately preceding control content is maintained for a certain period of time, making it possible to prevent index i from being used during a period that may be unstable.

[0064] Furthermore, the predetermined condition for determining the index i is set to a condition that makes it possible to determine whether or not there is a possibility that an abnormality has occurred in the average value, as described above. For example, when the amount of change Δi corresponds to the first state and the conditions of steps S4 and S5 are satisfied, it is assumed that no significant change has occurred in the index i even though cooking is in progress. In addition, when the amount of change Δi corresponds to the second state and satisfies the conditions of steps S4 and S5, it is assumed that the state in which index i deviates from 100 and fluctuates remains for a certain period of time and index i does not return to the vicinity of 100. In addition, when the amount of change Δi corresponds to the third state and satisfies the conditions of steps S4 and S5, it is assumed that the state in which index i deviates significantly from 100 and exhibits large fluctuations remains for a long period of time, and index i does not return to the vicinity of 100. If index i satisfies these conditions, there may be an anomaly in the average value.

[0065] When the motor 4b is not in the ON state, if the amount of change Δi corresponds to the first state and the condition of step S9 is satisfied, it is assumed that the ventilation unit 10 has not been used for a long period of time. In this case, even if the ventilation unit 10 has not been used for a long period of time, the index i is reset at regular intervals to keep it constant. In addition, when the motor 4b is not in the ON state, if the amount of change Δi corresponds to the third state and the condition of step S10 is satisfied, it is assumed that cooking is performed with the ventilation unit 10 stopped.

[0066] As described above, the above conditions include a condition for the index i and a condition for the amount of change Δi. Therefore, it is possible to precisely determine whether or not an abnormality has occurred in the average value.

[0067] [About verification testing] Next, a verification test carried out on this embodiment will be described. First, the results of checking the change in index i when the average value is reset will be described.

[0068] Fig. 6(a) is a graph showing an example of the change over time of index i when only index i is continuously obtained using the VOC sensor 24. Fig. 6(b) is a graph showing an example of the change over time of index i when the average value is reset. In FIG. 6(a) and FIG. 6(b), the vertical axis represents index i, and the horizontal axis represents time. 6(a) and 6(b) show the index i measured in the same test environment, in which cooking and other activities were not performed and the ventilation unit 10 was not operated.

[0069] As shown in FIG. 6(a), when the index i is calculated continuously, the index i increases as time passes. In contrast, in Fig. 6(b), the average value is reset approximately every hour. The average value is reset at time t1, time t2, and time t3. This shows that the index i is generally stable at around 100. From this result, it can be seen that if the average value is reset at a certain timing, the index i can be stabilized at around 100.

[0070] Next, the results of checking the change in index i when cooking is performed below range hood 1 will be described. FIG. 7 is a graph showing an example of a change in index i when cooking work is performed. In Fig. 7, the horizontal axis represents time. The upper part of Fig. 7 shows the change in index i. The lower part of Fig. 7 shows the duration of the cooking operation.

[0071] As shown in FIG. 7, the cooking operation is carried out between time t11 and time t13. At time t11, index i is near 100. When cooking work starts, index i rises to near 500. Time t12 is the time when index i is 300. After time t11, the index i exceeds 250 near time t12, so the processing unit 26 controls the motor 4b so that the airflow rate becomes "strong."

[0072] Although the cooking operation ends at time t13, index i continues to remain near 500. This is because index i represents the average value of the detected concentration over the past period. Therefore, even if the current concentration detected by the VOC sensor 24 has sufficiently decreased after the cooking operation is finished, the ventilation fan 4 continues ventilation at the "strong" airflow rate, and the index i remains near 500, so that the processing unit 26 maintains the "strong" airflow rate.

[0073] Time t14 is assumed to be 30 minutes after time t12. In this case, the state of index i is maintained in the third state from time t12 to time t14. Therefore, the processing unit 26 determines that index i corresponds to the third state at time t14 and that the third state has been maintained for 30 minutes (steps S4 and S5 in FIG. 4). Furthermore, the processing unit 26 resets the average value (step S6 in FIG. 4). The index i after time t14 is stable at around 100. In FIG. 7, the dashed line shows an example of how the index i changes when the average value is not reset.

[0074] In this way, if the average value is not reset, the index i (average value) will be maintained at a larger value than necessary, resulting in a large difference between the average value and the currently detected concentration, and a delay will occur before the currently detected concentration is reflected in the average concentration value, making it difficult to appropriately control the airflow according to the situation. In this regard, as shown in FIG. 7, according to this embodiment, it is possible to eliminate the difference between the current detected concentration and the index i by resetting the average value. These test results demonstrate that, according to this embodiment, it is possible to quickly reflect the currently detected concentration in the concentration index, and to appropriately control the air volume according to the situation.

[0075] 〔others〕 It should be noted that the embodiments disclosed herein are illustrative in all respects and are not restrictive. For example, in the above embodiment, a VOC sensor is used as the sensor for detecting the concentration of a pollutant, but a sensor other than a VOC sensor may be used as long as it detects the concentration of a pollutant.

[0076] In the above embodiment, the index i is a concentration index that represents the average value of the detected concentration as a relative value, but the index i may be the average value of the detected concentration as it is.

[0077] The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0078] 1. Range hood 2. Food 3. Blower box 4. Ventilation fan 4a Fan body 4b Motor 5 Inner Panel 5A opening 5B Magnetized part 6 Filters 7 Hinge 8 Magnetized part 9 Rectifier plate 10 Ventilation unit 20 Airflow control system 22 Control device 24 VOC sensor 26 Processing section 26a Calculation Processing 26b Control Processing 28 Memory section 500 Upper limit P1 position P2 position

Claims

1. A sensor for detecting a concentration of a pollutant in the indoor air; A control device for controlling the air volume of a ventilation fan that ventilates the room, The control device includes: A calculation process for determining a concentration index indicating a concentration of the pollutant based on an output of the sensor; a control process for controlling the air volume based on the concentration index, The arithmetic processing is A process of calculating the concentration index based on an average value of detected concentrations for a predetermined past period among detected concentrations obtained based on an output of the sensor; A process of determining whether the concentration index satisfies a predetermined condition; and resetting the average value when it is determined that the concentration index satisfies a predetermined condition. Airflow control system.

2. The control process includes, when the average value is reset, a process of maintaining the control content immediately before the average value is reset for a certain period of time after the average value is reset. The airflow control system according to claim 1 .

3. The predetermined conditions include at least a condition for the concentration index and a condition for a predetermined amount of change of the concentration index per unit time. The airflow control system according to claim 1 .

4. The predetermined condition includes that the concentration index is in one of the following three states: The airflow control system according to claim 3 . First state: the amount of change in the concentration index per unit time is less than a first threshold value, and the concentration index is less than a first lower limit value or equal to or greater than a first upper limit value. Second state: the amount of change in the concentration index per predetermined unit time is less than a second threshold value that is greater than the first threshold value, and the concentration index is less than a second lower limit value that is less than the first lower limit value or is equal to or greater than a second upper limit value that is greater than the first upper limit value. Third state: the amount of change in the concentration index per predetermined unit time is less than a third threshold value that is greater than the second threshold value, and the concentration index is less than a third lower limit value that is less than the second lower limit value or is equal to or greater than a third upper limit value that is greater than the second upper limit value

5. The predetermined condition includes that any one of the three states continues for a predetermined duration. The airflow control system according to claim 4.

6. The sensor includes a volatile organic compound sensor. The air volume control system according to any one of claims 1 to 5.

7. A ventilation fan to ventilate the room, a sensor for detecting a concentration of a contaminant in the air of the room; A control device for controlling the air volume of the ventilation fan, The control device includes: A calculation process for determining a concentration index indicating a concentration of the pollutant based on an output of the sensor; a control process for controlling the air volume based on the concentration index, The arithmetic processing is A process of calculating the concentration index based on an average value of detected concentrations for a predetermined past period among detected concentrations obtained based on an output of the sensor; A process of determining whether the concentration index satisfies a predetermined condition; and resetting the average value when it is determined that the concentration index satisfies a predetermined condition. Range hood.

8. A control device for controlling the air volume of a ventilation fan that ventilates a room, A calculation process for calculating a concentration index indicating a concentration of the pollutant based on an output of a sensor that detects the concentration of the pollutant in the indoor air; a control process for controlling the air volume based on the concentration index, The arithmetic processing is A process of calculating the concentration index based on an average value of detected concentrations for a predetermined past period among detected concentrations obtained based on an output of the sensor; A process of determining whether the concentration index satisfies a predetermined condition; and resetting the average value when it is determined that the concentration index satisfies a predetermined condition. Control device.

9. A computer program for causing a computer to execute a process for controlling an air volume of a ventilation fan that ventilates a room, The computer includes: a calculation step of determining a concentration index indicating a concentration of the pollutant based on an output of a sensor that detects the concentration of the pollutant in the indoor air; a control step of controlling the air volume based on the concentration index, The calculation step includes: determining the concentration index based on an average value of detected concentrations during a predetermined past period among detected concentrations obtained based on an output of the sensor; determining whether the concentration index satisfies a predetermined condition; and resetting the average value if it is determined that the concentration index satisfies a predetermined condition. Computer Programs

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