Ventilation system and ventilation method

Abstract

Provided is a ventilation system that performs ventilation control for a heating cooker for heating a cooking object by burning a gas containing hydrogen gas. This ventilation system 100 for an indoor space, in which a heating cooker BN for heating a cooking object by burning a gas containing hydrogen gas is used, the system comprises: an air quality sensor 20 that detects the oxygen concentration in the indoor space in which the heating cooker is used; a blower 30 that introduces air from an outdoor space into the indoor space by exhausting air from the indoor space to the outdoor space; and a control unit 10 that controls the blower on the basis of the oxygen concentration detected by the air quality sensor, the control unit causing the blower to operate in accordance with a first air volume to introduce the air when the air quality sensor has detected that the oxygen concentration is lower than a predetermined oxygen concentration.

Description

Ventilation system and ventilation method

[0001] The present invention relates to a ventilation system and a ventilation method.

[0002] Conventionally, heating cookers that use flammable gases containing carbon (such as methane and propane) as fuel have been widely used. In recent years, the use of hydrogen gas or hydrogen-mixed gas as clean energy for fuel has attracted attention. For example, Patent Document 1 discloses a technology that addresses the problem of falling water droplets generated when hydrogen fuel is used.

[0003] However, this document relates to a technology for heating cookers, and does not relate to a technology for performing ventilation control. That is, ventilation control adapted for heating cookers that use gas containing hydrogen gas as fuel has not yet been confirmed at this stage.

[0004] Japanese Unexamined Patent Publication No. 2014-114971

[0005] In ventilation control adapted for heating cookers that use flammable gas containing carbon as fuel, ventilation control is performed on the premise that flammable gas such as methane may leak, or carbon monoxide and carbon dioxide may be generated. However, in the case of a heating cooker that uses gas containing hydrogen gas as fuel, it is necessary to perform ventilation control according to the characteristics of the combustion gas from the heating cooker. For example, when hydrogen fuel is used in a heating cooker, the following changes in indoor air quality occur: ・No (low generation of) carbon monoxide and carbon dioxide ・Increase in water vapor accompanying combustion of hydrogen gas ・Decrease in oxygen concentration accompanying combustion of hydrogen gas ・Generation of nitrogen oxides (NOx) accompanying high-temperature combustion. For this reason, when hydrogen fuel (hydrogen gas, hydrogen-mixed gas) is used as fuel for a heating cooker, there has been a demand for a technology that performs ventilation control in accordance with the characteristics of such fuel.

[0006] Therefore, the present invention has been devised in view of such circumstances, and provides a ventilation system and a ventilation method that perform ventilation control adapted for a heating cooker that heats food by combusting gas containing hydrogen gas.

[0007] To solve the above problems, a ventilation system is provided for an indoor space in which a cooking appliance that heats food by burning a gas containing hydrogen gas is used, comprising: an air quality sensor that detects the oxygen concentration in the indoor space in which the cooking appliance is used; a blower that exhausts air from the indoor space to the outdoor space and takes in air from the outdoor space to the indoor space; and a control unit that controls the blower based on the oxygen concentration detected by the air quality sensor, wherein the control unit operates the blower at a first airflow rate to take in air when the air quality sensor detects an oxygen concentration lower than a predetermined oxygen concentration. According to this, when a cooking appliance that heats food by burning a gas containing hydrogen gas is used, a ventilation system is provided that can perform ventilation control corresponding to such a cooking appliance by controlling the airflow rate in response to the decrease in oxygen concentration due to the combustion of hydrogen gas.

[0008] Furthermore, the air quality sensor may detect the humidity of the indoor space, and the control unit may operate the blower at a second airflow rate to draw in air when the air quality sensor detects a humidity higher than a predetermined humidity. This allows for ventilation control that corresponds to a cooking appliance that uses hydrogen gas as fuel, by controlling the airflow rate based on the fact that water vapor increases with the combustion of hydrogen gas.

[0009] Furthermore, the air quality sensor may detect the concentration of harmful gases in the indoor space, and the control unit may, if the air quality sensor detects a concentration of harmful gases higher than a predetermined concentration, operate the blower at a third airflow rate, which is greater than the first airflow rate, to draw in air. This approach takes into account that when a mixed gas such as hydrogen gas and methane gas is used as fuel, harmful gases such as carbon dioxide are also generated, and by controlling the airflow rate with a large airflow rate, ventilation control corresponding to such cooking appliances can be performed.

[0010] Furthermore, the air quality sensor may detect the concentration of substances generated in the indoor space during cooking, and the control unit may operate the blower at the fourth airflow rate to draw in air when the air quality sensor detects that the concentration of substances generated during cooking is higher than a predetermined concentration. This allows for ventilation control that corresponds to a cooking appliance that uses hydrogen gas as fuel, by controlling the airflow rate while focusing on changes in oxygen concentration and changes in the concentration of substances generated during cooking.

[0011] Furthermore, the air quality sensor may detect the hydrogen concentration in the indoor space, and the control unit may operate the blower at a fifth airflow rate to draw in air if the air quality sensor detects a hydrogen concentration higher than a predetermined hydrogen concentration. This allows for early detection of hydrogen gas and prevents it from filling the room by controlling the airflow rate based on the fact that hydrogen can be detected in the event of a gas leak or combustion failure of the hydrogen gas used as fuel.

[0012] Furthermore, the air quality sensor may be positioned above and near the cooking appliance. This arrangement allows for the effective detection of a decrease in oxygen concentration caused by the use of the cooking appliance.

[0013] Furthermore, the control unit may be characterized by estimating the oxygen concentration near the cook's head based on the oxygen concentration detected by the air quality sensor when the cooking appliance is in combustion operation, and operating the blower at the sixth airflow rate to draw in air if the estimated oxygen concentration is lower than a predetermined oxygen concentration. According to this, an appropriate air environment for the user (cook) in the indoor environment can be created by estimating the oxygen concentration near the cook's head based on the detected oxygen concentration and operating the blower at the sixth airflow rate when necessary.

[0014] Furthermore, the control unit may be characterized by estimating the oxygen concentration near the cook's head based on the oxygen concentration detected by the air quality sensor when the cooking appliance is in combustion operation, and controlling the airflow of the blower according to the rate at which the estimated oxygen concentration decreases. This allows for the creation of an appropriate air environment for the user (cook) in the indoor environment by estimating the oxygen concentration near the cook's head based on the detected oxygen concentration and controlling the airflow of the blower according to the rate at which the estimated oxygen concentration decreases.

[0015] Furthermore, the system may also include a receiving unit that receives operating information from the cooking appliance, and the control unit may be characterized by estimating the oxygen concentration based on the operating information of the cooking appliance received by the receiving unit. According to this, by estimating the oxygen concentration based on the operating information of the cooking appliance, the estimation accuracy is improved, and the most comfortable air environment for the cook can be created through accurate estimation.

[0016] Furthermore, the system may be equipped with a flow rate changing mechanism that changes the flow rate in the exhaust air passage that exhausts indoor air to the outdoor space and the flow rate in the circulating air passage that circulates air back into the indoor space. The control unit may be characterized by controlling the flow rate changing mechanism to increase the flow rate in the exhaust air passage when the air quality sensor detects an oxygen concentration lower than a predetermined oxygen concentration, a humidity higher than a predetermined humidity, a harmful gas concentration higher than a predetermined harmful gas concentration, a substance generated during cooking higher than a predetermined concentration, or a hydrogen concentration higher than a predetermined hydrogen concentration. With this, by further equipping the flow path changing mechanism, ventilation control corresponding to the cooking appliance can be performed by controlling the flow path changing mechanism to increase the flow rate exhausted to the outside when ventilation is necessary, and when ventilation is not necessary, the flow rate circulating back into the room can be increased to maintain the circulation state as much as possible and keep the indoor air environment constant, reducing energy loss and creating an appropriate air environment.

[0017] To solve the above problems, a ventilation method is provided for an indoor space in which a cooking appliance that heats food by burning a gas containing hydrogen gas is used, wherein the ventilation method detects the oxygen concentration in the indoor space in which the cooking appliance is used, and if the detected oxygen concentration is lower than a predetermined oxygen concentration, operates a blower at a first airflow rate and controls the exhaust from the indoor space to the outdoor space, thereby drawing air from the outdoor space into the indoor space. According to this, when using a cooking appliance that heats food by burning a gas containing hydrogen gas, a ventilation method is provided that can perform ventilation control corresponding to such a cooking appliance by controlling the airflow rate based on the fact that the oxygen concentration decreases with the combustion of hydrogen gas.

[0018] As described above, the present invention provides a ventilation system and ventilation method that perform ventilation control corresponding to a cooking appliance that heats food by burning a gas containing hydrogen gas.

[0019] Block diagram of a range hood according to the first embodiment of the present invention. Example of a house in which the range hood according to the present invention is installed. Priority table used in the control unit of the range hood according to the first embodiment of the present invention. Control flowchart using the priority table of the control unit of the range hood according to the first embodiment of the present invention. Oxygen concentration estimation table used in the control unit of the range hood according to the second embodiment of the present invention. Control flowchart using the oxygen concentration estimation table of the control unit of the range hood according to the second embodiment of the present invention. Control flowchart third embodiment of the present invention.

[0020] The following describes each embodiment of the present invention with reference to the drawings. <First Embodiment> Referring to Figures 1 to 4, a range hood 100, which is a ventilation system for the indoor space in which the heating cooker BN in this embodiment is used, will be described. Here, the heating cooker BN in this specification is a type of cooker that heats food by burning a gas containing hydrogen gas in a burner. It receives a supply of gas containing hydrogen gas from a gas pipe, and burns this gas in a burner by the user's switch operation, etc., to heat the food. The heating cooker BN has a transmitter for transmitting combustion data, cooking data, etc. to the range hood 100. The transmitter may be infrared communication, wireless communication using radio waves, or wireless communication using visible light. The gas containing hydrogen gas may be 100% hydrogen gas, or a hydrogen mixed gas (for example, a mixture of hydrogen and LPG in a ratio of 80:20). The indoor spaces in which the BN heating appliance is used are open and connected spaces that are not completely separated by walls or partitions, such as the living-dining-kitchen (LDK) space in a house, the kitchen area and seating area in a restaurant, or the cooking area and sales area in a convenience store or other retail store.

[0021] The range hood 100 is positioned above or to the side of the cooking appliance BN and sucks in oil fumes, odor-causing substances, water vapor, etc., generated by cooking performed by the cooking appliance BN, along with the indoor air, and exhausts them to the outside. The range hood 100 includes a control unit 10 that controls the functions of the range hood 100 itself, an air intake port 90 that draws in indoor air, an outdoor exhaust port 71 that exhausts the drawn-in air to the outside, a blower 30 that generates an airflow from the air intake port 90 to the outdoor exhaust port 71, an air quality sensor 20 that detects the air quality of the indoor space in which the cooking appliance BN is used, a receiving unit 50 that receives data from the transmitting unit of the cooking appliance BN, a switch 60 (including a remote control) that accepts operation from the user, and a storage unit 80 that stores information (described later) necessary for controlling the control unit 10.

[0022] Furthermore, the range hood 100 may also be equipped with a circulation indoor exhaust port 72 for returning the intake air to the room and circulating it, and a damper mechanism 40 (flow path changing mechanism) that changes the flow rate in the exhaust air path that exhausts the indoor air to the outdoor space and the flow rate in the circulation air path that circulates the air back into the room, in addition to exhausting the intake air to the outside space.

[0023] The control unit 10 is composed of a microprocessor that performs various calculations and controls the operation of the blower 30 and other components based on signals from the receiver 50, information from the air quality sensor 20, and user instructions from the switch 60, according to control programs such as the OS (Operating System), programs that define various processing procedures for the blower 30 and other components, and information stored in the memory unit 80, thereby controlling the overall function of the range hood 100. Normally, the control unit 10 operates the blower 30 at a rotation speed defined according to user instructions, such as low airflow, low airflow, medium airflow, and high airflow.

[0024] The blower 30 is not particularly limited as long as it is a fan that generates airflow from the intake port 90 to the outdoor exhaust port 71, and is generally an axial flow fan or a sirocco fan with relatively high static pressure. When the blower 30 is started to exhaust air, the room becomes negatively pressurized, so by exhausting air from the indoor space to the outdoor space, air is drawn in from the outdoor space into the indoor space through the intake port and gaps.

[0025] The air quality sensor 20 is a sensor that detects various air quality characteristics of the air in an indoor space. Air quality refers to the substances that make up the air (e.g., oxygen, hydrogen, carbon monoxide, carbon dioxide, etc.), substances contained in the air (e.g., moisture, oil, dust, particulate matter, nitrogen oxides (NOx), volatile organic compounds (VOCs), odor substances, etc., in particulate or gaseous form), an indicator of the kinetic energy of the air (temperature), and other gases, including so-called harmful gases. It is a concept that indicates the quality of air that humans can perceive or be affected by. The air quality sensor 20 may detect some or all of these characteristics.

[0026] Harmful gases refer to gaseous or particulate substances that are harmful to human health. Common examples, in addition to those mentioned above, include hydrogen sulfide, oxygen deficiency, ammonia, benzene, sulfur dioxide, and chlorine. Normally, air contains approximately 21% oxygen and 0.00005% hydrogen. For example, if the air quality sensor 20 detects the oxygen concentration in the indoor space and the oxygen concentration is lower than the normal 21% or the hydrogen concentration is higher than 0.00005%, the control unit 10 may increase the airflow of the blower 30 based on the oxygen and hydrogen concentrations detected by the air quality sensor 20 in order to return the air to normal by taking in air from the outside space. The air quality sensor 20 may include an oxygen concentration sensor 21, a hydrogen sensor 22, a temperature and humidity sensor 23, a CO2 sensor 24, a VOC sensor 25, a dust sensor 26, a NOx sensor 27, a thermosensor 28, etc.

[0027] Furthermore, although Figure 1 shows the air quality sensor 20 being placed inside the housing of the range hood 100, it is not limited to this, and may be placed in various locations in the room space, for example, as shown in Figure 2. For example, the air quality sensor 20 placed at a is positioned on the front of the hood of the range hood 100, near and above the cooking appliance BN; the air quality sensor 20 placed at b is positioned on the wall surrounding the cooking appliance BN, above the cooking appliance BN; the air quality sensor 20 placed at c is positioned on the dining table as a portable sensor unit; the air quality sensor 20 placed at d is positioned on the wall of the living room, away from the range hood 100 and windows, and in an area where people are active; and the air quality sensor 20 placed at e is positioned in a location incorporated into the room ventilation fan. It can be placed in a variety of locations.

[0028] The air quality sensor 20 located at a is in the closest position to the cook's head, making it suitable for detecting the decrease in oxygen concentration caused by the use of the cooking appliance BN, and is effective in most appropriately representing the air quality of the air the cook breathes. The air quality sensor 20 located at b is in the closest position to the cooking appliance BN, making it effective in most appropriately representing the air quality of the combustion gas from the cooking appliance BN. The air quality sensor 20 located at c is in the closest position when cooking with a tabletop stove that uses hydrogen gas, making it effective in most appropriately representing the air quality of the combustion gas from the tabletop stove. The air quality sensor 20 located at d is in a position where many people are actually present in the room, making it effective in most appropriately representing the air quality of the air the occupants breathe. The air quality sensor 20 located at e is in a position where the air in the room gathers, making it effective in most appropriately representing the air quality of the room.

[0029] These air quality sensors 20 may be placed in only one location for detection, or they may be placed in multiple locations and used in combination for detection. For example, by combining the air quality sensor 20 placed at a and the air quality sensor 20 placed at d, it is possible to detect changes in the oxygen concentration throughout the room as well as local changes in oxygen concentration. Furthermore, when multiple sensors are placed in multiple locations and used in combination for detection, the air quality sensors 20 may detect different air quality conditions. For example, the air quality sensor 20 placed at a may be an oxygen concentration sensor, and the air quality sensor 20 placed at d may be a combined sensor unit of an oxygen concentration sensor and a CO2 sensor. In this way, ventilation control is performed based on information from multiple air quality sensors, which reduces false detections due to temporary fluctuations.

[0030] Furthermore, the threshold values ​​of the air quality sensors 20 may differ depending on their location. For example, the threshold value of the oxygen concentration sensor 21 of the air quality sensor 20 located at a may be set to 20.5%, the threshold value of the oxygen concentration sensor 21 of the air quality sensor 20 located at b may be set to a slightly lower 20.3% because it is the first to be affected by oxygen consumption due to hydrogen combustion, and the threshold value of the oxygen concentration sensor 21 of the air quality sensor 20 located at d may be set to a slightly higher 20.7% because it takes time for the decrease in oxygen due to hydrogen combustion to diffuse.

[0031] Furthermore, since the air quality sensors 20 located at a and b are close to the cooking appliance BN and are susceptible to temporary fluctuations, the control unit 10 may perform ventilation control not only based on whether the detected value for a short period (at the time of detection) has reached the threshold, but also based on whether the average value of the detected values ​​over a certain period of time has reached the threshold. In addition, the control unit 10 operates the blower 30 when each air quality sensor exceeds the threshold, but it may also set and control the airflow according to the position of the air quality sensor 20. For example, if an air quality sensor 20 located far from the range hood 100, such as at d and e, reaches the threshold, it is highly likely that the oxygen concentration of the entire room has decreased rather than being a localized change, so the blower 30 may be operated with a relatively large airflow. If an air quality sensor 20 close to the cooking appliance BN, such as at a, reaches the threshold, the control unit 10 may check whether it is a temporary fluctuation and then operate the blower 30 with a standard airflow.

[0032] The damper mechanism 40 is positioned between the blower 30 and the outdoor exhaust port 71 and the indoor exhaust port 72 for circulation. When the entire volume of intake air is to flow to the outdoor exhaust port 71, the damper is controlled to fully open the air passage to the outdoor exhaust port 71 and close the air passage to the indoor exhaust port 72 for circulation. Conversely, when the entire volume of intake air is to flow to the indoor exhaust port 72 for circulation, the damper is controlled to fully open the air passage to the indoor exhaust port 72 for circulation and close the air passage to the outdoor exhaust port 71. The damper mechanism 40 may also be controlled to perform exhaust and circulation simultaneously. For example, the exhaust airflow may be set to 70% of the total airflow, and the circulation airflow to 30% of the total airflow.

[0033] Referring to Figure 4, the control method of the control unit 10 (ventilation control process S100) will be explained. Note that S stands for step. In S102, the control unit 10 receives a signal from the heating cooker BN via the receiving unit 50 indicating that the operation of the gas stove has started. In S104, the control unit 10 acquires the sensor value detected by the air quality sensor 20, including the oxygen concentration sensor 21. In S106, the control unit 10 checks whether the sensor value has reached a threshold. The threshold is defined for each object (parameter) to be detected, as shown in Figure 3, and is stored in the storage unit 80. The control unit 10 refers to the threshold for each parameter stored in the storage unit 80 and checks whether the sensor value has reached the threshold.

[0034] For example, if the parameter is oxygen concentration, its threshold is 20.50%. The control unit 10 determines that an oxygen-deficient state exists if the detected oxygen concentration is 20.50% or less, when the normal oxygen concentration is 21%. Similarly, if the parameter is hydrogen concentration, its threshold is 1% (10,000 ppm). The control unit 10 determines that an excess hydrogen concentration exists if the detected hydrogen concentration is 1% or more, when the normal hydrogen concentration is 0.00005%. Furthermore, each parameter has a priority order according to its level of risk. If sensor values ​​for multiple parameters show abnormal values, the control unit 10 makes a decision according to the priority order.

[0035] The priority table shown in this figure sets priorities based on the magnitude of the health risk to the human body and the speed at which it occurs. Priority 1 (highest priority) is hydrogen concentration, which poses a risk of explosion depending on the concentration, and this is a life-threatening danger. For this reason, it has the highest priority. Priority 2 (second highest priority) is harmful gas concentration (e.g., CO2 concentration), which can cause headaches and dizziness depending on the concentration and tends to have an immediate effect. It is also generated in the case of hydrogen mixed gases, and because it reaches the threshold at which health risks occur faster than other parameters, it is set as the second highest priority. Priority 3 (third highest priority) is oxygen concentration, which poses a risk of impaired consciousness if it decreases for a long period of time, so it is set as the third highest priority. Priority 4 (fourth highest priority) is humidity, which has little direct impact on health but causes discomfort and condensation, so it is set as the fourth highest priority. Priority 5 (fifth highest priority) is VOC / dust concentration, which poses the lowest immediate health risk if it is VOC or dust generated during cooking, so it is set as the lowest priority.

[0036] Priorities may be set not only by those shown in this diagram, but also by other criteria. The diagram assumes that hydrogen gas or hydrogen-mixed gas is being burned, i.e., that cooking is being done with hydrogen gas. However, for example, there may be a priority table that assumes non-cooking conditions. In this case, the priorities may be set higher than those assumed during cooking, with hydrogen concentration as priority 1, harmful gas concentration (CO2 concentration) as priority 2, and VOC / dust concentration as priority 3, and oxygen concentration as priority 4 and humidity as priority 5. Some VOCs pose a significant health risk. If VOCs rise rapidly, such as when paint is spilled indoors, ventilation control may be prioritized over oxygen concentration and humidity.

[0037] Furthermore, the appropriate airflow rate is determined according to the parameters, and the control unit 10, for example, if it determines that an oxygen-deficient state is present, sets the normal airflow rate (200 m³). ３ The blower 30 is operated at a rate of 0 / h, and if it is determined that the harmful gas concentration is abnormal (CO2 concentration of 1400 ppm or higher in Figure 3), the rapid airflow rate (300 m) is increased. ３ The blower 30 is operated at 400 m³ / h, and if it is determined that the hydrogen concentration is excessive, the rapid maximum airflow (400 m³) is increased.３ The blower 30 is operated at / h).

[0038] If the threshold has not been reached, the control unit 10 returns to S104 and acquires sensor values ​​every 5 seconds. If the threshold has been reached, in S108, the control unit 10 checks whether the threshold has been reached for multiple parameters and, if so, refers to the priority. In S110, the control unit 10 checks whether the hydrogen concentration, which has the highest priority, has reached the threshold. If the hydrogen concentration has reached the threshold, in S112, the control unit 10 operates the blower 30 at a predetermined rapid maximum airflow rate. If the hydrogen concentration has not reached the threshold, in S118, the control unit 10 checks whether the harmful gas, which has the second highest priority, has reached the threshold. If the harmful gas has reached the threshold, in S120, the control unit 10 operates the blower 30 at a predetermined rapid airflow rate.

[0039] If the harmful gas level does not reach the threshold, in S122, the control unit 10 operates the blower 30 at the normal airflow rate, assuming that there were no high-priority abnormal values. After starting to operate the blower 30 at a predetermined airflow rate as described above, in S114, the control unit 10 obtains the latest sensor values ​​from the air quality sensor 20 and checks whether the sensor values ​​have fallen below the threshold due to the intake of air from the outdoor space. If the values ​​have fallen below the threshold, the control unit 10 stops the operation of the blower 30 in S116. If the values ​​have not fallen below the threshold, the control unit 10 returns to S104 and repeats the process from S104 onward. In this embodiment, the operation of the blower 30 is stopped, but this is not the only option. For example, the blower 30 may be decelerated, decelerated in stages, returned to the airflow rate before the transition, operated at a low airflow rate before stopping, or operated intermittently.

[0040] As described above, the control unit 10 controls the blower 30 based on the oxygen concentration detected by the oxygen concentration sensor 21, which detects the oxygen concentration in the indoor space where the cooking appliance BN is used. More specifically, when the oxygen concentration sensor 21 detects an oxygen concentration lower than a predetermined oxygen concentration set lower than the oxygen concentration of normal air, the control unit 10 operates the blower 30 at the first airflow rate (normal airflow rate in the above case) to take in air. In this way, when the cooking appliance BN, which heats food by burning gas containing hydrogen gas, is used, the range hood 100 can perform ventilation control corresponding to such a cooking appliance BN by controlling the airflow rate based on the fact that the oxygen concentration decreases with the combustion of hydrogen gas.

[0041] Furthermore, the above also describes a ventilation method for indoor spaces where a cooking appliance BN, which heats food by burning a gas containing hydrogen gas, is used. This ventilation method detects the oxygen concentration in the indoor space where the cooking appliance BN is used, and if the detected oxygen concentration is lower than a predetermined oxygen concentration, it operates the blower 30 at a first airflow rate, exhausting air from the indoor space to the outdoor space and controlling the intake of air from the outdoor space into the indoor space. According to this, when using a cooking appliance BN that heats food by burning a gas containing hydrogen gas, by controlling the airflow rate in accordance with the decrease in oxygen concentration due to the combustion of hydrogen gas, it is possible to provide a ventilation method that can perform ventilation control corresponding to such a cooking appliance BN.

[0042] Furthermore, the control unit 10 may control the blower 30 based on the concentration of harmful gases detected by a CO2 sensor 24, a NOx sensor 27, or other sensors that detect the concentration of harmful gases in the indoor space. More specifically, if these sensors detect a concentration of harmful gases higher than a predetermined concentration, the control unit 10 may operate the blower 30 at a third airflow rate (rapid airflow rate in the above example) that is larger than the first airflow rate to take in air. This allows the range hood 100 to perform ventilation control corresponding to such a cooking appliance BN by controlling the airflow rate with a large airflow rate, taking into account that harmful gases such as carbon dioxide are also generated when a mixed gas such as hydrogen gas and methane gas is used as fuel.

[0043] Furthermore, the control unit 10 may control the blower 30 based on the hydrogen gas concentration detected by the hydrogen sensor 22 that detects the hydrogen gas concentration in the indoor space. More specifically, when the hydrogen sensor 22 detects a hydrogen concentration higher than a predetermined hydrogen concentration set higher than the hydrogen concentration in normal air, the control unit 10 may operate the blower 30 at a fifth air volume (rapid maximum air volume in the above description) to draw in air. According to this configuration, the range hood 100 can detect hydrogen gas at an early stage and prevent the gas from filling the room by performing air volume control based on the finding that hydrogen can be detected when there is a gas leak of hydrogen fuel or poor combustion. The fifth air volume is not limited to being set larger than the third air volume, and may be the same as the third air volume or may be set lower than the third air volume. This relationship between air volumes is appropriately set according to the indoor environment. For example, in an environment such as an open kitchen where people stay for a long time and air is easily diffused, it is preferable to continuously suppress CO₂. In such an environment, the fifth air volume may be set lower than the third air volume.

[0044] Furthermore, the control unit 10 may control the blower 30 based on the gas concentration detected by the NOx sensor 27 or the VOC sensor 25 that detects the concentration of substances generated by cooking in the indoor space. More specifically, when the control unit 10 detects the concentration of these substances generated by cooking in the indoor space and detects that the concentration of these substances is higher than a predetermined concentration, the control unit 10 may operate the blower 30 at a fourth air volume to draw in air. According to this configuration, the range hood 100 can perform ventilation control compatible with a heating cooker BN that uses hydrogen gas as fuel by performing air volume control focusing on changes in oxygen concentration and changes in the concentration of substances generated accompanying cooking.

[0045] Furthermore, the control unit 10 may control the blower 30 based on the humidity detected by the temperature and humidity sensor 23 that detects the humidity in the indoor space. When the temperature and humidity sensor 23 detects a humidity higher than a predetermined humidity, the control unit 10 may operate the blower 30 at a second air volume to draw in air. The first air volume, the second air volume, and the fourth air volume may be the same air volume or may be different air volumes.

[0046] Furthermore, the second air volume, the fourth air volume and the third air volume may be the same, the second air volume and the fourth air volume may be larger than the third air volume, or the third air volume and the fifth air volume may be the same. That is, the air volume may be appropriately set according to the purpose of control and the target indoor environment. For example, if energy efficiency is the purpose of control, in order to suppress unnecessary maximum-volume operation, the air volume when the threshold is reached may be uniformly the same from the first air volume to the fifth air volume, and the air volume may be increased stepwise according to the situation.

[0047] Furthermore, if the purpose is to optimize the environment during cooking, it is possible to detect large fluctuations in humidity and VOC concentration, and set an air volume of the same level as the third air volume, which is larger than the first air volume, for the second air volume and the fourth air volume. In addition, if the purpose is to optimize the environment where there are many people or the staying time is long, it is possible to detect changes in oxygen concentration and CO₂ concentration, and perform control such that the first air volume and the third air volume are set to air volumes of the same level (rapid air volume) to keep the oxygen and CO₂ levels constant.

[0048] <Second Embodiment> Referring to Figs. 5 and 6, a range hood 100, which is a ventilation system for an indoor space where a cooking device BN according to the present embodiment is used, will be described. The structure of the range hood 100 in the present embodiment is the same as that of the above embodiment (Fig. 1), and the description of the structure explained above is omitted to avoid redundant description. In the present embodiment, the oxygen concentration sensor 21 is disposed at position a, which is above and near the cooking device BN in Fig. 2, and is positioned closest to the cook's head, so it is disposed at the most suitable position for detecting a decrease in oxygen concentration caused by the use of the cooking device BN.

[0049] In the oxygen concentration estimation table of Fig. 5, a position 5 cm from the burner of the cooking device BN is defined as the vicinity of the burner, and it is assumed based on experimental results that the oxygen concentration changes from 21% to 15% immediately after ignition. Since the oxygen concentration sensor 21 is disposed at a position on the front surface of the hood 80 cm away from the burner, the value in this column is compared with the actual sensor value. The cook's head (the nose and mouth for breathing) is located at a position 50 cm away from the burner, which is an intermediate position between the vicinity of the burner and the front surface of the hood.

[0050] Assuming such a positional distribution in a typical indoor space, these tables show estimated changes in the oxygen concentration distribution based on the time elapsed since the start of combustion and the airflow rate of the blower 30, based on experimental results and fluid simulations. In other words, it can be seen that the oxygen concentration decreases with the passage of time due to hydrogen combustion, and at the location where the cook's head is located, which is the most important point, the oxygen concentration is slightly lower than the oxygen concentration detected by the oxygen concentration sensor 21 at the front of the hood. In this embodiment, the control unit 10 controls the range hood 100 using this oxygen concentration estimation table.

[0051] Figure 6 shows the control method (ventilation control process S200) of the control unit 10 in this embodiment. In the ventilation control process S200, the control starts when the automatic mode is selected, in which the oxygen concentration is estimated by the operation of switch 60 and the fan is controlled automatically. In S202, the control unit 10 acquires the sensor value regarding the oxygen concentration in the indoor space detected by the oxygen concentration sensor 21 before ignition and sets this as the initial value (non-cooking state in Figure 5: 21.0%). In S204, the control unit 10 receives information via the receiving unit 50 that the operation of the gas stove has started in the heating cooker BN and information regarding the heat output. Information regarding heat output includes burner information (for example, in the case of a three-burner stove, information on which burner is actually being used among the high-power burner, standard-power burner, and low-power burner), as well as approximate heat output information such as 3,900 kcal / h for the high-power burner, 2,600 kcal / h for the standard-power burner, and 1,500 kcal / h for the low-power burner. This information also includes information on the heat output during operation, such as whether the high-power burner is set to high heat (3,900 kcal / h) or whether the low-power burner is set to simmer (860 kcal / h).

[0052] In S206, the control unit 10 reads out an oxygen concentration estimation table corresponding to the heat output of the burner in use of the cooking appliance BN. As shown in Figure 5, there are three types of oxygen concentration estimation tables: (A) normal ventilation table, (B) rapid ventilation table, and (C) slow ventilation table, all of which are stored in the storage unit 80. Here, (A) normal ventilation table is used when using two burners, a high-power burner and a standard burner, with the high-power burner set to medium to high heat and the standard burner set to medium heat. (B) rapid ventilation table is used when using two burners, a high-power burner and a standard burner, with the high-power burner set to high heat and the standard burner also set to high heat. (C) slow ventilation table is used when using two burners, a high-power burner and a standard burner, with the high-power burner set to low heat and the standard burner set to simmer.

[0053] Therefore, when the control unit 10 receives information about the heat output in addition to the on / off status of the cooking appliance BN, i.e., the actual amount of heat used by the burner during operation (kW), it can estimate the oxygen concentration based on the oxygen consumption amount according to the oxygen concentration estimation table corresponding to this amount of heat used, and control it appropriately. For example, if the control unit 10 receives information that the burner in use is a high-power burner and a high flame setting has been applied, it reads out the (B) rapid ventilation table.

[0054] In S208, the control unit 10 acquires the current sensor value from the oxygen concentration sensor 21. In S210, the control unit 10 checks whether the acquired sensor value has reached a predetermined threshold requiring ventilation. The determination of whether the predetermined threshold has been reached is the same as the determination described in the above embodiment. If the predetermined threshold has been reached, in S226, the control unit 10 performs a predetermined ventilation control according to the oxygen concentration parameter. If the predetermined threshold has not been reached, in S212, the control unit 10 acquires the sensor value from the oxygen concentration sensor 21 every minute and monitors the oxygen concentration.

[0055] During monitoring, in S214, the control unit 10 compares the acquired oxygen concentration sensor value and the elapsed time information since the start of operation of the cooking appliance BN with the read-out oxygen concentration estimation table. In S216, the control unit 10 checks whether the compared oxygen concentration sensor value is a value that requires ventilation. For example, (A) when referring to the normal ventilation table, if a 0.2% decrease in oxygen concentration (oxygen concentration of 20.8%) is detected 15 minutes after the start of combustion of the cooking appliance BN, it is determined that this is a value that requires ventilation. That is, at 15 minutes after the start of combustion, the oxygen concentration near the cook's head (50 cm) is estimated to be 20.5%, and ventilation is performed at the normal airflow rate.

[0056] Furthermore, the control unit 10 can not only control based on such an estimated value at a single point in time, but can also perform control based on a decreasing trend. For example, if the control unit 10 estimates that the oxygen concentration will decrease from 20.5% after 15 minutes from the start of combustion of the cooking appliance BN to 20.4% after 20 minutes, it may perform airflow control according to the decreasing trend of the oxygen concentration. In this case, the control unit 10 may determine that the oxygen concentration decreases by 0.1% in 5 minutes, which is within the typical range in an environment where combustion equipment is used, and that if ventilation is performed earlier according to the rate of decrease, it will be sufficient even without the normal airflow. Therefore, after 15 minutes, instead of ventilation at the normal airflow, it may perform intermittent ventilation at a weaker airflow to continuously prevent the oxygen concentration from reaching the threshold.

[0057] Thus, when the heating appliance BN is in combustion operation, the control unit 10 may estimate the oxygen concentration near the cook's head based on the oxygen concentration detected by the oxygen concentration sensor 21, and if the estimated oxygen concentration is lower than a predetermined oxygen concentration, it may control the blower to take in air at the sixth airflow rate. This allows for the estimation of the oxygen concentration near the cook's head based on the detected oxygen concentration, and by operating the blower 30 at the sixth airflow rate when necessary, an appropriate air environment can be created for the user (cook) in the indoor environment. The sixth airflow rate may be the same as or different from the first, second, and fourth airflow rates described above. Also, the sixth airflow rate may be the same as or different from the third airflow rate, and the sixth airflow rate may be the same as or different from the fifth airflow rate. In other words, the setting of the sixth airflow rate may be set appropriately according to the purpose of control, the target indoor environment, and the situation of oxygen concentration estimation.

[0058] Furthermore, for example, when referring to (B) the rapid ventilation table, if a 0.2% decrease in oxygen concentration (oxygen concentration of 20.8%) is detected 5 minutes after the start of combustion of the cooking appliance BN, it is determined that ventilation is necessary. That is, 5 minutes after the start of combustion, it is estimated that the oxygen concentration near the cook's head will fall below the ventilation threshold (20.5%) (20.4%) 2 minutes later, so considering the rapid rate of decrease in oxygen concentration, ventilation is performed with a rapid airflow. Also, for example, when referring to (C) the slow ventilation table, if a 0.2% decrease in oxygen concentration (oxygen concentration of 20.8%) is detected 30 minutes after the start of combustion of the cooking appliance BN, it is estimated that 10 minutes after the start of combustion, the oxygen concentration near the cook's head will be close to the ventilation threshold, so considering the slow rate of decrease in oxygen concentration, ventilation is performed with a slow airflow. In this way, by having multiple oxygen concentration estimation tables according to the airflow generated by the blower 30, it is possible to estimate various rates of decrease in oxygen concentration.

[0059] Thus, when the heating appliance BN is in combustion operation, the control unit 10 may estimate the oxygen concentration near the cook's head based on the oxygen concentration detected by the oxygen concentration sensor 21, and control the airflow rate of the blower 30 according to the rate at which the estimated oxygen concentration decreases. By doing so, an appropriate air environment can be created for the user (cook) in the indoor environment by estimating the oxygen concentration near the cook's head based on the detected oxygen concentration and controlling the airflow rate of the blower 30 according to the rate at which the estimated oxygen concentration decreases.

[0060] If the compared oxygen concentration sensor value is a value that requires ventilation, the control unit 10 performs ventilation control in S218 by referring to the corresponding oxygen concentration estimation table. If the sensor value is not a value that requires ventilation, the control unit 10 checks in S224 whether the value of the air quality sensor 20 other than the oxygen concentration sensor 21 is a sensor value that requires ventilation. If the sensor value is a value that requires ventilation, the control unit 10 performs predetermined ventilation control according to each parameter in S226.

[0061] Next, in S220, the control unit 10 checks whether there is an instruction to change the operation via switch 60. If there is an instruction to change the operation, in S222, the control unit 10 terminates the automatic mode and changes to the instructed operating state; if there is no instruction, it terminates without doing anything. While the automatic mode is set, the control unit 10 operates based on the oxygen concentration estimation table and the values ​​of the air quality sensor 20, and when input is received from switch 60, it prioritizes this operation and terminates the automatic mode.

[0062] Figure 7 shows a modified example of the control method of the control unit 10 in this embodiment (ventilation control process S300). In S302, the control unit 10 acquires the sensor value regarding the oxygen concentration in the indoor space detected by the oxygen concentration sensor 21 before ignition and sets this as the initial value (non-cooking state in Figure 5: 21.0%). In S304, the control unit 10 receives information via the receiving unit 50 that the operation of the gas stove has started in the cooking appliance BN and information regarding its heat output. In S306, the control unit 10 reads out an oxygen concentration estimation table corresponding to the heat output of the burner in use in the cooking appliance BN.

[0063] The control unit 10 may also estimate the oxygen concentration based on the operating information of the cooking appliance BN received by the receiving unit 50. The operating information of the cooking appliance BN refers not only to on / off information but also to information about the heat output, such as whether a high-power burner is being used, how high the heat output is, and how many burners are being used. By estimating the oxygen concentration based on the operating information of the cooking appliance BN, the estimation accuracy is improved, and an air environment that is most comfortable for the cook can be created through accurate estimation.

[0064] In S308, the control unit 10 obtains the current sensor value from the oxygen concentration sensor 21. In S310, the control unit 10 checks whether the obtained sensor value has reached a predetermined threshold requiring ventilation. If the predetermined threshold has been reached, in S328, the control unit 10 controls the damper mechanism 40 to exhaust the intake air from the outdoor exhaust port 71. If the predetermined threshold has not been reached, in S312, the control unit 10 controls the damper mechanism 40 to exhaust the intake air from the indoor circulating exhaust port 72.

[0065] Next, in S314, the control unit 10 acquires the sensor value of the oxygen concentration sensor 21 every minute and monitors the oxygen concentration. During monitoring, in S316, the control unit 10 compares the acquired oxygen concentration sensor value with the read oxygen concentration estimation table. In S318, the control unit 10 checks whether the compared oxygen concentration sensor value is a value that requires ventilation. If the compared oxygen concentration sensor value is a value that requires ventilation, the control unit 10 executes ventilation control in S328. If the sensor value is not a value that requires ventilation, the control unit 10 checks in S320 whether the value of the air quality sensor 20 other than the oxygen concentration is a sensor value that requires ventilation. If the sensor value is a value that requires ventilation, the control unit 10 performs predetermined ventilation control in S328. If the sensor value is not a value that requires ventilation, the control unit 10 continues circulating operation in S322.

[0066] Next, in S324, the control unit 10 checks whether there is an instruction to change the operation via switch 60. If there is an instruction to change the operation, in S326, the control unit 10 terminates the automatic circulating ventilation operation and changes to the instructed operating state; if there is no instruction, it terminates without doing anything.

[0067] <Third Embodiment> Referring to Figure 8, the range hood 100, which is a ventilation system for the indoor space in which the cooking appliance BN in this embodiment is used, will be described. The structure of the range hood 100 in this embodiment is the same as in the above embodiment (Figure 1), and in order to avoid redundant explanation, the explanation of the structure described above will be omitted.

[0068] Figure 8 shows a modified example of the control method of the control unit 10 in this embodiment (circulation ventilation control process S400). In S402, the control unit 10 receives a signal via the receiving unit 50 indicating that the operation of the gas stove has started in the heating cooker BN. In S404, the control unit 10 obtains the current sensor value from the air quality sensor 20. In S406, the control unit 10 checks whether the obtained sensor value has reached a predetermined threshold requiring ventilation. If the predetermined threshold has been reached, in S422, the control unit 10 controls the damper mechanism 40 to exhaust the intake air from the outdoor exhaust port 71. If the predetermined threshold has not been reached, in S408, the control unit 10 controls the damper mechanism 40 to exhaust the intake air from the indoor circulation exhaust port 72.

[0069] Next, in S410, the control unit 10 acquires sensor values ​​from the air quality sensor 20 every minute and monitors the sensor values ​​of each sensor. During monitoring, in S412, the control unit 10 checks whether the acquired oxygen concentration sensor value is a value that requires ventilation. If the compared oxygen concentration sensor value is a value that requires ventilation, in S422, the control unit 10 performs a predetermined ventilation control according to the oxygen concentration parameter. If that sensor value is not a value that requires ventilation, in S414, the control unit 10 checks whether the values ​​of the air quality sensors 20 other than oxygen concentration are sensor values ​​that require ventilation. If those sensor values ​​are values ​​that require ventilation, in S422, the control unit 10 performs a predetermined ventilation control according to the parameter. If those sensor values ​​are not values ​​that require ventilation, in S416, the control unit 10 continues the circulation operation.

[0070] Furthermore, while S422 states that the intake air is exhausted from the outdoor exhaust port 71, and S408 / S416 states that the intake air is exhausted from the indoor circulating exhaust port 72, this does not mean setting the airflow of one to 0% and the other to 100%. Rather, "In S422, the intake air is exhausted from the outdoor exhaust port 71" includes increasing the proportion of intake air exhausted from the outdoor exhaust port 71 (decreasing the proportion exhausted from the indoor circulating exhaust port 72), and "In S408 / S416, the intake air is exhausted from the indoor circulating exhaust port 72" includes increasing the proportion of intake air exhausted from the indoor circulating exhaust port 72 (decreasing the proportion exhausted from the outdoor exhaust port 71).

[0071] For example, in seasons with comfortable temperatures and humidity where outside air can be actively utilized, the proportion of outdoor exhaust can be increased, such as outdoor:indoor = 80:20. Also, in winter when outside temperatures are low, or in summer when air conditioners are running, it is desirable to minimize heat loss due to ventilation and the decrease in cooling efficiency, so the proportion of circulating indoor exhaust can be increased, such as outdoor:indoor = 20:80, in order to ventilate while reusing indoor air as much as possible. Furthermore, when cooking with a heating cooker BN, the ratio can be changed depending on the concentration of substances generated during cooking, for example, outdoor:indoor = 70:30 for grilled fish and outdoor:indoor = 10:90 for simmered dishes.

[0072] Thus, the range hood 100 has a damper mechanism 40, and when ventilation is necessary, that is, when the air quality sensor 20 detects an oxygen concentration lower than a predetermined oxygen concentration, a humidity higher than a predetermined humidity, a harmful gas concentration higher than a predetermined harmful gas concentration, or a substance generated during cooking at a concentration higher than a predetermined concentration, or a hydrogen concentration higher than a predetermined hydrogen concentration, the control unit 10 can increase the flow rate in the exhaust air passage and control the damper mechanism 40 to increase the flow rate to exhaust to the outside, thereby performing ventilation control corresponding to the cooking appliance BN. Furthermore, when ventilation is not necessary, the flow rate circulating into the room can be increased to maintain the circulation state as much as possible and keep the indoor air environment constant, reducing energy loss and creating an appropriate air environment.

[0073] Next, in S418, the control unit 10 checks whether there is an instruction to change the operation via switch 60. If there is an instruction to change the operation, in S420, the control unit 10 terminates the automatic circulating ventilation operation and changes to the instructed operating state; if there is no instruction, it terminates without doing anything.

[0074] It should be noted that the present invention is not limited to the exemplary embodiments, and can be implemented in configurations that do not depart from the content described in each claim. In other words, although the present invention is illustrated and described in particular with respect to specific embodiments, those skilled in the art can make various modifications to the embodiments described above in terms of quantity and other detailed configurations without departing from the scope of the technical idea and objectives of the present invention.

[0075] 100 Range hood 10 Control unit 20 Air quality sensor 21 Oxygen concentration sensor 22 Hydrogen sensor 23 Temperature and humidity sensor 24 CO2 sensor 25 VOC sensor 30 Blower 40 Damper mechanism (flow path change mechanism) 50 Receiver 60 Range hood switch 70 Exhaust port 71 Outdoor exhaust port 72 Indoor exhaust port for circulation 80 Memory unit BN Cooking appliance (gas stove)

Claims

1. A ventilation system for an indoor space in which a cooking appliance that heats food by burning a gas containing hydrogen gas is used, comprising: an air quality sensor that detects the oxygen concentration in the indoor space in which the cooking appliance is used; a blower that exhausts air from the indoor space to the outdoor space and takes in air from the outdoor space to the indoor space; and a control unit that controls the blower based on the oxygen concentration detected by the air quality sensor, wherein the control unit operates the blower at a first airflow rate to take in air when the air quality sensor detects an oxygen concentration lower than a predetermined oxygen concentration.

2. The ventilation system according to claim 1, characterized in that the air quality sensor detects the humidity of the indoor space, and the control unit operates the blower at a second airflow rate to take in air when the air quality sensor detects a humidity higher than a predetermined humidity.

3. The ventilation system according to claim 1, characterized in that the air quality sensor detects the concentration of harmful gases in the indoor space, and when the air quality sensor detects a concentration of harmful gases higher than a predetermined concentration, the control unit operates the blower at a third airflow rate greater than the first airflow rate to take in air.

4. The ventilation system according to claim 1, characterized in that the air quality sensor detects the concentration of substances generated in the indoor space during cooking, and the control unit operates the blower at a fourth airflow rate to take in air when the air quality sensor detects that the concentration of substances generated during cooking is higher than a predetermined concentration.

5. The ventilation system according to claim 1, characterized in that the air quality sensor detects the hydrogen concentration in the indoor space, and the control unit operates the blower at a fifth airflow rate to take in air when the air quality sensor detects a hydrogen concentration higher than a predetermined hydrogen concentration.

6. The ventilation system according to any one of claims 1 to 5, characterized in that the air quality sensor is positioned above and near the cooking appliance.

7. The ventilation system according to claim 6, characterized in that the control unit estimates the oxygen concentration near the cook's head based on the oxygen concentration detected by the air quality sensor when the heating appliance is in combustion operation, and operates the blower at a sixth airflow rate to take in air if the estimated oxygen concentration is lower than a predetermined oxygen concentration.

8. The ventilation system according to claim 6, characterized in that the control unit estimates the oxygen concentration near the cook's head based on the oxygen concentration detected by the air quality sensor when the cooking appliance is in combustion operation, and controls the airflow rate of the blower according to the rate of decrease of the estimated oxygen concentration.

9. The ventilation system according to claim 6, further comprising a receiving unit that receives operating information of a cooking appliance from the cooking appliance, wherein the control unit estimates the oxygen concentration based on the operating information of the cooking appliance received by the receiving unit.

10. The ventilation system according to claim 6, comprising a flow rate changing mechanism that changes the flow rate in an exhaust air passage that exhausts indoor air to an outdoor space and the flow rate in a circulating air passage that circulates air back into the indoor space, wherein the control unit controls the flow rate changing mechanism to increase the flow rate in the exhaust air passage when the air quality sensor detects an oxygen concentration lower than a predetermined oxygen concentration, a humidity higher than a predetermined humidity, a harmful gas concentration higher than a predetermined harmful gas concentration, or a concentration of substances generated during cooking higher than a predetermined concentration, or a hydrogen concentration higher than a predetermined hydrogen concentration.

11. A ventilation method for an indoor space in which a cooking appliance that heats food by burning a gas containing hydrogen gas is used, wherein the method detects the oxygen concentration in the indoor space in which the cooking appliance is used, and if the detected oxygen concentration is lower than a predetermined oxygen concentration, operates a blower at a first airflow rate and controls the system to exhaust air from the indoor space to the outdoor space, thereby drawing air from the outdoor space into the indoor space.

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