WO2024100833A1

WO2024100833A1 - Heat exchange-type ventilation device

Info

Publication number: WO2024100833A1
Application number: PCT/JP2022/041881
Authority: WO
Inventors: 真也加藤; 庸充松原; 晃治岩田; 嘉範藤井
Original assignee: 三菱電機株式会社
Priority date: 2022-11-10
Filing date: 2022-11-10
Publication date: 2024-05-16

Abstract

This heat exchange-type ventilation device, which uses a heat exchange element to perform heat exchange between air passing through an exhaust air passage and air passing through a supply air passage, comprises: a housing having formed therein a circulation air passage opening which connects a portion of the supply air passage downstream of the heat exchange element and a portion of the exhaust air passage upstream of the heat exchange element; a circulation air passage damper which opens and closes the circulation air passage opening; an air cleaning unit which cleans air passing through the circulation air passage opening; and a control unit which, when the circulation air passage damper opens the circulation air passage opening, controls an exhaust air blower to increase the output of the exhaust air blower.

Description

Heat exchange ventilation system

This disclosure relates to a heat exchange ventilation device.

Conventionally, there is a heat exchange type ventilation device that has an intake air duct that supplies fresh air from the outside with an intake fan and an exhaust air duct that exhausts dirty air from the inside with an exhaust fan, and exchanges heat between the intake air and the exhaust air while performing so-called first-class ventilation that simultaneously supplies and exhausts air. There is also a heat exchange type ventilation device that has a circulation air duct opening that connects a part of the intake air duct and a part of the exhaust air duct, and a filter for air purification is installed in the circulation air duct opening. Air sucked from inside the room is passed through the circulation air duct opening, purified by the filter, and returned to the room. For example, the heat exchange type ventilation device shown in Patent Document 1 is provided with an opening/closing damper that opens and closes the bypass opening, which is the circulation air duct opening, and when the opening/closing damper is opened, the air sucked from inside the room is divided into an airflow that flows through the exhaust air duct and an airflow that flows through the bypass opening.

JP 2002-206778 A

When the open/close damper switches from the closed state to the open state, a circulating air volume is generated, and the air volume discharged from the exhaust outlet decreases. The filter installed in the bypass opening cannot remove all pollutants from the air passing through, and can only efficiently remove certain substances. Therefore, for substances that cannot be removed by the filter, there is an issue that the room cannot be cleaned by the amount of the reduced air volume discharged from the exhaust outlet. Furthermore, if the substance continues to be generated indoors, its concentration will increase over time. For example, a normal dust removal filter can remove dust, but not gas components. Therefore, carbon dioxide emitted with human activity, or volatile organic compound (VOC) gases generated from walls, etc. cannot be removed by the filter, so the indoor concentration of gas components as pollutants increases as the exhaust air volume decreases.

The present disclosure therefore aims to provide a heat exchange ventilation device that ensures an appropriate volume of air exhausted to the outside, even when performing so-called circulation air purification, in which a portion of the air exhausted from the room is purified and then led back into the room.

The heat exchange type ventilation device disclosed herein exchanges heat between air passing through an exhaust air duct and air passing through an intake air duct using a heat exchange element, and includes a housing having a circulation air duct opening that connects a portion of the intake air duct downstream of the heat exchange element and a portion of the exhaust air duct upstream of the heat exchange element, a circulation air duct damper that opens and closes the circulation air duct opening, an air purifying unit that purifies the air passing through the circulation air duct opening, and a control unit that controls the exhaust blower to increase the output of the exhaust blower when the circulation air duct damper opens the circulation air duct opening.

The heat exchange ventilation device disclosed herein can ensure an appropriate volume of air to be exhausted to the outside, even when air purification is performed through circulation.

FIG. 1 is a schematic diagram showing the configuration of a heat exchange type ventilation device 100 according to a first embodiment. FIG. 1 is a schematic diagram showing the configuration of a heat exchange type ventilation device 100 in a circulating operation state. 1 is a flowchart showing a method for controlling the operation of a heat exchange ventilation device 100. A block diagram showing an example of the hardware configuration of a control circuit 15a included in the heat exchange type ventilation device 100. FIG. 11 is a configuration diagram showing a specific example of a table for controlling the exhaust fan 8 according to a second modification of the first embodiment; FIG. 11 is a configuration diagram showing a specific example of a table for controlling the exhaust fan 8 according to a third modification of the first embodiment; FIG. 11 is a block diagram showing a specific example of a table for controlling the supply air blower 7 according to a fourth modification of the first embodiment; FIG. 13 is a configuration diagram showing a specific example of a table for controlling the intake air blower 7 and the exhaust air blower 8 according to a fifth modification of the first embodiment. FIG. 13 is a schematic diagram showing the configuration of a heat exchange type ventilation device 100a according to a 9th modification of the first embodiment. FIG. 13 is a schematic diagram showing the configuration of a heat exchange type ventilation device 100b according to a tenth modification of the first embodiment. FIG. 13 is a schematic diagram showing the configuration of a heat exchange type ventilation device 200 according to a second embodiment. FIG. 11 is a configuration diagram showing a specific example of a table for controlling the circulating-air-path damper 10 according to a modification of the second embodiment;

Below, an embodiment of the present disclosure will be described with reference to the drawings. Note that in the drawings and the following description, identical or substantially identical parts are given the same reference numerals. Therefore, descriptions of parts given the same reference numerals will not be repeated.

Embodiment 1.
FIG. 1 is a schematic diagram of a heat exchange type ventilation device 100 according to a first embodiment of the present disclosure. The heat exchange type ventilation device 100 includes a housing 1 having an outdoor intake port 3a, an indoor exhaust port 4a, an indoor intake port 5a, and an outdoor exhaust port 6a. The housing 1 has two

cylindrical connectors

3 and 6 protruding outward from one side thereof, and the openings at the tips of the connectors are the outdoor intake port 3a and the outdoor exhaust port 6a, respectively. The housing 1 has two

cylindrical connectors

5 and 4 protruding outward from the opposite side thereof, and the openings at the tips of the connectors are the indoor intake port 5a and the indoor exhaust port 4a, respectively. The

connectors

3 and 6 are connected to ducts leading to the outside of the room, and the

connectors

5 and 4 are connected to ducts leading to the inside of the room. Inside the housing 1, an intake air duct 101 connecting the outdoor intake port 3a and the indoor exhaust port 4a, and an exhaust air duct 102 connecting the indoor intake port 5a and the outdoor exhaust port 6a are formed.

The heat exchange type ventilation device 100 further includes a heat exchange element 2, an intake air blower 7, an exhaust air blower 8, a circulation air duct damper 10, an intake air shutter 11, an air purifier 12, and a controller 15. The heat exchange element 2 is provided in the housing 1, and exchanges heat between the air passing through the intake air duct 101 and the air passing through the exhaust air duct 102. The intake air blower 7 is provided in the intake air duct 101, and generates an air flow from the outdoor inlet 3a to the indoor outlet 4a. The intake air blower 7 is specifically provided in the intake air duct 101 between the heat exchange element 2 and the indoor outlet 4a, for example, near the indoor outlet 4a. The intake air blower 7 has a motor and a fan that is driven by the motor to rotate, and generates an air flow in the intake air duct 101 by the rotation of the fan.

The exhaust fan 8 is provided in the exhaust duct 102 and generates an air flow from the indoor inlet 5a to the outdoor outlet 6a. Specifically, the exhaust fan 8 is provided in the exhaust duct 102 between the heat exchange element 2 and the outdoor outlet 6a, for example, near the outdoor outlet 6a. The exhaust fan 8 has a motor and a fan that is driven by the motor to rotate, and generates an air flow in the exhaust duct 102 by the rotation of the fan.

A circulation air duct opening 9 is formed inside the housing 1, connecting the portion of the intake air duct 101 downstream of the heat exchange element 2 with the portion of the exhaust air duct 102 upstream of the heat exchange element 2. The circulation air duct opening 9 is formed in a partition wall that separates the intake air duct 101 downstream of the heat exchange element 2 from the intake air duct 101 upstream of the heat exchange element 2. The circulation air duct damper 10 opens and closes the circulation air duct opening 9. The circulation air duct damper 10 is attached to the circulation air duct opening 9 so as to be rotatable about its axis, and is arranged to face the exhaust air duct 102. When the circulation air duct damper 10 is in a closed state, it blocks the circulation air duct opening 9. When the circulation air duct damper 10 is axially rotated toward the exhaust air duct 102, the circulation air duct damper 10 is in an open state, opening the circulation air duct opening 9. Therefore, when the circulation air duct damper 10 is open, air flows through the circulation air duct opening 9, and when the circulation air duct damper 10 is closed, the air flow through the circulation air duct opening 9 is blocked.

The air purifier 12 is provided at the air circulation duct opening 9 and purifies the air flowing through the air circulation duct opening 9.

The intake air shutter 11 is provided in the intake air duct 101 upstream of the circulation air duct opening 9, and opens and closes the intake air duct 101. The intake air shutter 11 is attached inside the housing 1 so that it can rotate on its axis. When the intake air shutter 11 is in the closed state, it blocks the air duct inside the connection part 3, blocking the air flow in the intake air duct 101. When the intake air shutter 11 rotates on its axis toward the inside of the housing 1, the intake air shutter 11 opens, allowing air to flow in the intake air duct 101.

The control unit 15 controls the operation of the intake air blower 7 and the exhaust air blower 8, and controls the opening and closing of the circulating air duct damper 10 and the intake air shutter 11. The control unit 15 comprises a control box attached to the outer surface of the housing 1, and a control board housed within the control box and equipped with a control circuit 15a. This control circuit 15a is responsible for the control performed by the control unit 15. This control circuit 15a may be referred to as the "control unit".

The control unit 15 is connected to an operation switch (not shown) by wire or wirelessly, and receives a command to start operation from the operation switch. In response to the command, the heat exchange type ventilation device 100 performs heat exchange operation. The heat exchange operation is an operation state in which heat exchange is performed between the airflows flowing through the supply air duct 101 and the exhaust air duct 102 with the circulation air duct opening 9 closed. In the heat exchange operation, the control unit 15 operates the supply air blower 7 and the exhaust air blower 8 with the circulation air duct damper 10 in a closed state and the supply air shutter 11 in an open state. Therefore, as shown in FIG. 1, indoor air is sucked into the indoor intake port 5a and exhausted to the outside through the exhaust air duct 102 and the outdoor discharge port 6a, and at the same time, outdoor air is sucked into the outdoor intake port 3a and supplied to the room through the supply air duct 101 and the indoor discharge port 4a. The heat exchange element 2 then exchanges heat between the exhaust air and the supply air.

The heat exchange type ventilation device 100 also performs circulation operation. Circulation operation is an operating state in which the circulation air duct opening 9 is open and generates an airflow in the circulation air duct 103. The circulation air duct 103 is an air duct that connects the indoor intake port 5a and the indoor exhaust port 4a through the circulation air duct opening 9. In circulation operation, the control unit 15 operates the intake air blower 7 and the exhaust air blower 8 with the circulation air duct damper 10 in an open state and the intake air shutter 11 in a closed state. The circulation air duct damper 10 is in an open state and opens the circulation air duct opening 9. Even when the circulation air duct damper 10 is in an open state, it does not block the exhaust air duct 102. Therefore, as shown in FIG. 2, airflow is generated in the exhaust air duct 102 and the circulation air duct 103. In other words, a part of the indoor air sucked in from the indoor intake port 5a is exhausted to the outside through the heat exchange element 2 and the outdoor exhaust port 6a, and the other air is returned to the room through the circulation air duct opening 9 and the indoor exhaust port 4a. Furthermore, since the air intake shutter 11 is closed, no air flows in through the outdoor intake port 3a.

The control unit 15 switches between heat exchange operation and circulation operation. Specifically, the control unit 15 switches the operation state from heat exchange operation to circulation operation when the indoor air is polluted to a certain standard amount or more. For this reason, the heat exchange type ventilation device 100 is equipped with an air pollution level detection unit 13. The air pollution level detection unit 13 detects the pollution level of the air taken in from the indoor air inlet 5a. The amount of a specific pollutant contained in the air, for example, the concentration of the substance in the air, is detected as the pollution level of the air. An example of the air pollution level detection unit 13 is an air quality sensor. The air pollution level detection unit 13 is provided in the exhaust air duct 102 upstream of the circulation air duct opening 9, for example, inside the connection unit 5. The results detected by the air pollution level detection unit 13 are sent to the control unit 15. Hereinafter, the substance detected by the air pollution level detection unit 13 will be referred to as the "detected substance."

The control unit 15 controls the circulating air duct damper 10 and the intake air shutter 11 based on the detection results sent from the air pollution level detection unit 13. Specifically, the control unit 15 judges whether the detected substance in the indoor air is contained in a certain standard amount or more from the detection results of the air pollution level detection unit 13. The control unit 15 pre-stores a threshold value (threshold value A' described below) indicating the standard amount within the control unit 15, and compares the amount of detected substance detected by the air pollution level detection unit 13 with the threshold value. If it is determined that the amount of detected substance is equal to or more than the threshold value, the control unit 15 opens the circulating air duct damper 10 and closes the intake air shutter 11.

In circulation operation, air flows through the circulation air duct opening 9 and is purified by the air purifier 12. The air purifier 12 removes detected substances detected by the air pollution level detector 13. Some of the detected substances in the air sucked in from the indoor air inlet 5a are removed by the air purifier 12, and the remaining part is discharged to the outside from the outdoor discharge outlet 6a via the exhaust air duct 102.
The detection substance detected by the air pollution level detection unit 13 is set to at least one of carbon monoxide, carbon dioxide, volatile organic compounds, fine particulate matter (so-called PM2.5), dust, pollen, viruses, and odorous substances. The air purifying unit 12 has a function of removing at least the set detection substance. If the set detection substance is one or both of dust and pollen, the air purifying unit 12 is, for example, a filter made of a net, nonwoven fabric, etc., an electric dust collecting device that applies a high voltage to two electrodes and passes air between them to collect the viruses at the electrodes, etc. If the set detection substance is fine particulate matter, the air purifying unit 12 is, for example, a HEPA (High Efficiency Particle Air) filter, etc. If the set detection substance is a virus, the air purifying unit 12 is, for example, a HEPA filter, an electric virus inactivation device that applies a high voltage to two electrodes and passes air between them to inactivate the viruses, etc. If the set detection substance is at least one of carbon monoxide, carbon dioxide, and volatile organic compounds, the air purifying unit 12 is, for example, an activated carbon filter, a filter containing a chemical substance specialized for adsorbing each gas, etc. Furthermore, if the set detection substance is odor, the air purifying unit 12 is, for example, an activated carbon filter, a photocatalyst filter, etc. However, these are merely examples, and the air purifying unit 12 is not limited to these.

The heat exchange type ventilation device 100 further includes an air volume detection unit 14a and an air volume detection unit 14b. The air volume detection unit 14a is provided in the exhaust air duct 102 downstream of the exhaust fan 8, and detects the volume of air discharged to the outside from the outdoor discharge port 6a. The air volume detection unit 14a is, for example, a differential pressure sensor, and is provided inside the connection unit 6. The air volume detection unit 14a transmits a value indicating the volume of air discharged from the outdoor discharge port 6a as the detection result to the control unit 15. The air volume is the volume of air flowing per unit time. The control unit 15 adjusts the output of the exhaust fan 8 based on the detection result transmitted from the air volume detection unit 14a. Hereinafter, the air volume of air discharged to the outside from the outdoor discharge port 6a will be referred to as the "exhaust air volume."

The air volume detection unit 14b is provided in the supply air duct 101 downstream of the supply air blower 7, and detects the volume of air supplied from the indoor discharge port 4a to the room. The air volume detection unit 14b is, for example, a differential pressure sensor, and is provided inside the connection unit 4. The air volume detection unit 14b outputs a value indicating the volume of air supplied from the indoor discharge port 4a as the detection result to the control unit 15. The control unit 15 adjusts the output of the supply air blower 7 based on the detection result sent from the air volume detection unit 14b. Hereinafter, the volume of air supplied from the indoor discharge port 4a to the room in heat exchange operation is referred to as the "supply air volume", and the volume of air supplied from the indoor discharge port 4a to the room in circulation operation is referred to as the "circulation air volume".

In circulation operation, indoor air is taken into the heat exchange type ventilation device 100 by both the intake air blower 7 and the exhaust air blower 8, so the volume of air taken in from the room is greater than in heat exchange operation. This promotes the removal of the detected substances detected by the air pollution level detection unit 13. On the other hand, in circulation operation, the air taken in from the indoor intake port 5a branches within the housing 1 and is discharged from the outdoor discharge port 6a and the indoor discharge port 4a. Due to this branching of the air, the exhaust air volume in circulation operation is smaller than the exhaust air volume in heat exchange operation. Since the air purification unit 12 is not effective or has difficulty in removing pollutants other than the set detected substances, in circulation operation, the amount of the pollutants discharged is reduced compared to heat exchange operation. Therefore, when the operation state is switched from heat exchange operation to circulation operation, the control unit 15 controls the exhaust air blower 8 to increase its output.

In addition, generally, when the air purification unit 12 is composed of a filter, the pressure loss in the filter is large, and the pressure loss in the air path from the indoor intake port 5a to the indoor discharge port 4a in circulation operation is greater than the pressure loss in the air path from the outdoor intake port 3a to the indoor discharge port 4a in heat exchange operation. Therefore, the circulating air volume in circulation operation is also smaller than the supply air volume in heat exchange operation. In order to increase the amount of detected substances removed by the air purification unit 12, the control unit 15 controls the supply air blower 7 to also increase its output when the operating state is switched from heat exchange operation to circulation operation.

The output of each of the intake air blower 7 and exhaust air blower 8 refers to the output of each motor, and is expressed as the product of the motor torque and the motor rotation speed. When the output of the blower increases, the fan rotation speed also increases, and the volume of the airflow generated by the blower increases. The control unit 15 sets an operation command value for each blower, and adjusts the output of each blower by appropriately changing this operation command value. The operation command value is expressed, for example, as a command voltage corresponding to the drive voltage supplied to the motor. The control unit 15 transmits an operation control signal corresponding to the operation command value to the drive circuit of each blower. The intake air blower 7 and exhaust air blower 8 operate according to their respective operation command values.

Next, a method for controlling the operation of the heat exchange type ventilation device 100 will be described using the flowchart shown in Figure 3. Here, a case will be described in which the output of the exhaust blower 8 and the supply air blower 7 is increased so that the exhaust air volume and the circulation air volume in circulation operation are equal to the exhaust air volume and the supply air volume in heat exchange operation, respectively. When a command to start operation is received from the operation switch, the heat exchange type ventilation device 100 starts heat exchange operation in step S01. The control unit 15 opens the supply air shutter 11 and operates the supply air blower 7 and the exhaust blower 8 with the circulation air duct damper 10 closed. The supply air blower 7 and the exhaust blower 8 are operated, for example, so that the exhaust air volume and the supply air volume are approximately the same.

In step S02, the control unit 15 reads the air pollution level detection value A from the air pollution level detection unit 13. The control unit 15 also reads the supply air volume detection value B and the exhaust air volume detection value C from the air volume detection units 14b and 14a, respectively. The air pollution level detection value A, the supply air volume detection value B, and the exhaust air volume detection value C are values that indicate the amount of detected substance, the supply air volume, and the exhaust air volume, respectively, during heat exchange operation.

In step S03, the control unit 15 compares the air pollution level detection value A with the threshold value A' stored in the control unit 15. If it is determined that the air pollution level detection value A is smaller than the threshold value A', the process returns to step S01 and the heat exchange operation continues. If it is determined that the air pollution level detection value A is equal to or greater than the threshold value A', the process passes through step S04 and circulation operation is performed in step S05. In other words, air pollution level detection value A being equal to or greater than the threshold value A' means that the air is polluted above the standard value. In step S04, the control unit 15 stores the supply air flow rate detection value B and exhaust air flow rate detection value C read in step S02 in the control unit 15.

In step S05, the operating state of the heat exchange type ventilation device 100 switches from heat exchange operation to circulation operation. The control unit 15 closes the intake air shutter 11 and opens the circulation air duct damper 10. At this point, the output of the intake air blower 7 and the exhaust air blower 8 continues to be output in heat exchange operation. In step S06, the control unit 15 reads the circulation air volume detection value B' and the exhaust air volume detection value C' from the air volume detection units 14b and 14a, respectively. The circulation air volume detection value B' and the exhaust air volume detection value C' are values that indicate the circulation air volume and exhaust air volume, respectively, in circulation operation.

In step S07, the control unit 15 compares the exhaust airflow detection value C' with the exhaust airflow detection value C stored in the control unit 15. If the exhaust airflow detection value C' is smaller than the exhaust airflow detection value C, the control unit 15 increases the output of the exhaust blower 8 in step S09. Thus, the exhaust airflow increases. Then, the process of step S06 is performed again. On the other hand, if the exhaust airflow detection value C' is larger than the exhaust airflow detection value C, the control unit 15 decreases the output of the exhaust blower 8 in step S08. Thus, the exhaust airflow decreases. Then, the process of step S06 is performed again. The respective increase/decrease amounts of the output of the exhaust blower 8 in steps S08 and S09 correspond to the difference value between the exhaust airflow detection value C' and the exhaust airflow detection value C. The relationship between the difference value and the increase/decrease amount of the output of the exhaust blower 8 is determined in advance.

Immediately after the operating state switches from heat exchange operation to circulation operation, the exhaust air volume decreases, so in the first step S07 after circulation operation starts, it is determined that exhaust air volume detection value C' is smaller than exhaust air volume detection value C, and the output of exhaust blower 8 is increased in step S09. If the increased exhaust air volume falls below exhaust air volume detection value C, the output of exhaust blower 8 is further increased, and if the increased exhaust air volume exceeds exhaust air volume detection value C, the output of exhaust blower 8 is decreased. By repeating this operation, exhaust air volume detection value C' is brought closer to exhaust air volume detection value C.

If it is determined in step S07 that the exhaust airflow detection value C' is equal to the exhaust airflow detection value C, the process proceeds to step S10. In step S10, the control unit 15 compares the circulation airflow detection value B' with the supply airflow detection value B stored in the control unit 15. If the circulation airflow detection value B' is smaller than the supply airflow detection value B, the control unit 15 increases the output of the supply air blower 7 in step S12. Thus, the circulation airflow increases. Then, the process of step S06 is performed again. If the circulation airflow detection value B' is larger than the supply airflow detection value B, the control unit 15 decreases the output of the supply air blower 7 in step S11. Thus, the circulation airflow decreases. Then, the process of step S06 is performed again. The increase or decrease in the output of the supply air blower 7 in steps S11 and S12 is an amount corresponding to the difference between the circulation airflow detection value B' and the supply airflow detection value B. The relationship between the difference and the increase or decrease in the output of the supply air blower 7 is determined in advance.

Immediately after the operating state switches from heat exchange operation to circulation operation, the circulation air volume becomes smaller than the supply air volume, so in the first step S10 after the start of circulation operation, it is determined that the circulation air volume detection value B' is smaller than the supply air volume detection value B, and the output of the supply air blower 7 is increased in step S12. At this time, the change in the output of the supply air blower 7 may cause the exhaust air volume to deviate from the state equal to the exhaust air volume detection value C. Therefore, the control unit 15 repeats the processing of steps S07 to S09, and adjusts the output of the exhaust blower 8 again so that the exhaust air volume detection value C' becomes equal to the exhaust air volume detection value C. The control unit 15 then performs the processing of step S10 again.

If it is determined in step S10 that the circulating air volume detection value B' is equal to the supply air volume detection value B, the process returns to step S02. In step S02 for circulation operation, the circulating air volume detected by the air volume detection unit 14b is read as the supply air volume detection value B. If the determination in step S03 is "No", the circulation operation continues. Since the circulation air volume detection value B' and the exhaust air volume detection value C' read in the subsequent step S06 are already equal to the supply air volume detection value B and the exhaust air volume detection value C, respectively, the output of the supply air blower 7 and the exhaust air blower 8 is not changed and the process returns to step S02 again.

On the other hand, if the answer is "Yes" in step S03 after step S02 as the circulation operation, the process returns to step S01, and the operation state is switched from the circulation operation to the heat exchange operation. At this time, the control unit 15 controls the intake air blower 7 and the exhaust air blower 8 so that the outputs of the intake air blower 7 and the exhaust air blower 8 are returned to those of the heat exchange operation performed before the circulation operation.

By the above control, the exhaust air volume in exhaust operation after the air volume adjustment period is equal to the exhaust air volume in heat exchange operation, and the circulation air volume in circulation operation after the air volume adjustment period is equal to the supply air volume in heat exchange operation. The air volume adjustment period is the period during which the air volume is adjusted after the operating state is switched from heat exchange operation to circulation operation, and in Figure 3, it corresponds to the period from the first step S06 after the start of circulation operation to returning to step S02.

In addition, instead of reading the supply air volume detection value B and the exhaust air volume detection value C in step S02, the control unit 15 may read the supply air volume detection value B and the exhaust air volume detection value C from the air volume detection units 14b and 14a in step S04 and store them in the control unit 15. Also, when the determination in step S03 is "No," if the operating state is circulation operation, the process may return to step S02 without proceeding to step S04.

Furthermore, the determination of equality in steps S07 and S10 does not necessarily mean strict agreement, but also includes cases where the values roughly match. For example, in step S07, the control unit 15 may determine whether the exhaust airflow detection value C' is within a certain range that includes the exhaust airflow detection value C, or whether it is higher than the upper limit of the range or lower than the lower limit of the range. The width of this range is sufficiently smaller than the difference between the exhaust airflow detection value C and the exhaust airflow detection value C' detected in the first step S06 after the start of exhaust operation. The same can be considered for step S10.

FIG. 4 is a block diagram showing an example of the hardware configuration of the control circuit 15a. The control circuit 15a is a microcomputer composed of semiconductor integrated circuits, and includes a processor 21, a memory 22, a bus 23, three input circuits 24, two output circuits 25, and two output circuits 26. The processor 21 performs the process shown in FIG. 3 according to a program. The program is stored in the memory 22 and is provided to the processor 21 via the bus 23. The processor 21 is, for example, a central processing unit (CPU), and the memory 22 is a storage device including a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory) or a flash memory. The threshold value A' used in step S03 is, for example, stored in the non-volatile memory of the memory 22, and in step S04, the supply airflow detection value B and the exhaust airflow detection value C are stored in the volatile memory of the memory 22.

The bus 23 is connected to the processor 21, the memory 22, three input circuits 24, two output circuits 25, and two output circuits 26. The three input circuits 24 receive the detection results output from the air pollution level detection unit 13 and the air volume detection units 14a and 14b, respectively, and transfer them to the processor 21 via the bus 23. The detection results are temporarily stored in the memory 22, and may also be read from the memory 22 into the processor 21.

The two output circuits 25 receive operation control signals output from the processor 21 and send them to the intake air blower 7 and exhaust air blower 8, respectively. The two output circuits 26 receive opening/closing control signals output from the processor 21 and send them to the circulation air duct damper 10 and intake air shutter 11. The circulation air duct damper 10 and intake air shutter 11 open and close in accordance with the opening/closing control signals. These operation control signals and opening/closing control signals may be temporarily stored in the memory 22 from the processor 21, and then sent from the memory 22 to the respective output circuits. The operation control signals and opening/closing control signals may also be processed as necessary in each output circuit and sent to the respective destinations.

In this way, the control circuit 15a can be configured with a microcomputer that can also be used to control other electrical or electronic devices. However, this is not limited to this, and some or all of the processing shown in FIG. 3 can also be realized by a dedicated processing circuit.

The heat exchange ventilation device 100 configured in this manner provides the following effects:

When the circulation air duct damper 10 opens the circulation air duct opening 9, the control unit 15 controls the exhaust fan 8 to increase its output. Since the reduction in exhaust air volume caused by the circulation air duct opening 9 being open can be suppressed, an appropriate amount of air can be ensured to be exhausted to the outside even when air purification is performed by circulation operation. As a result, indoor pollutants that are not removed by the air purification unit 12 can be quickly exhausted to the outside.

In addition, during circulation operation, indoor air is taken in by both the intake air blower 7 and the exhaust air blower 8 into the heat exchange type ventilation device 100, so the volume of air taken in from inside the room is greater than in heat exchange operation. If an attempt is made to take in the same volume of air from inside the room during heat exchange operation as the volume of air taken in during circulation operation and exhaust it to the outside, the output of the exhaust air blower 8 must be increased more than in circulation operation. However, because indoor air is taken in by both the intake air blower 7 and the exhaust air blower 8, the output of each blower can be reduced. As a result, the heat exchange type ventilation device 100 achieves low noise levels.

The air pollution level detection unit 13 detects the pollution level of the air taken in from the indoor air inlet 5a, and the control unit 15 controls the circulating air duct damper 10 to open based on the results detected by the air pollution level detection unit 13. Therefore, if the air in the room becomes polluted, the circulating air duct damper 10 can be opened and closed automatically.

When the air circulation duct damper 10 opens the air circulation duct opening 9, the control unit 15 controls the exhaust blower 8 to increase the output of the air supply blower 7. This increases the amount of air purified by the air purification unit 12.

When the circulation air duct damper 10 opens the circulation air duct opening 9, the control unit 15 controls the intake air shutter 11 to close the intake air duct 101. This makes it possible to increase the amount of air purified by the air purification unit 12 compared to when air is taken in from the outdoor intake port 3a.

Next, we will explain modified examples of the heat exchange ventilation device 100.

(Variation 1)
The control unit 15 may be configured to change the output of each of the intake air blower 7 and the exhaust air blower 8 to a plurality of output levels. Hereinafter, each level will be referred to as an "air volume notch."

When the control unit 15 switches the operating state from heat exchange operation to circulation operation, it changes the air volume notch of the exhaust blower 8, and at each change, it compares the exhaust air volume detection value C' detected by the air volume detection unit 14a with the exhaust air volume detection value C detected in the heat exchange operation. The control unit 15 also changes the air volume notch of the supply air blower 7, and at each change, it compares the circulation air volume detection value B' detected by the air volume detection unit 14b with the supply air volume detection value B detected in the heat exchange operation. These operations of changing the air volume notch and comparing the detection values are appropriately repeated, and finally, the control unit 15 adjusts the output of the exhaust blower 8 to an output level at which the exhaust air volume detection value C' is closest to the exhaust air volume detection value C among the multiple adjustable output levels of the exhaust blower 8. The control unit 15 also adjusts the output of the supply air blower 7 to an output level at which the circulation air volume detection value B' is closest to the supply air volume detection value B among the multiple adjustable output levels of the supply air blower 7.

Therefore, the exhaust air volume in the circulation operation after the output adjustment period becomes close to the exhaust air volume in the heat exchange operation, and the circulation air volume in the circulation operation after the output adjustment period becomes close to the supply air volume in the heat exchange operation. At this time, the outputs of the exhaust fan 8 and the supply fan 7 in the circulation operation after the output adjustment period are controlled to be larger than the outputs of the exhaust fan 8 and the supply fan 7 in the heat exchange operation.
(Variation 2)
The air volume detection units 14a and 14b do not necessarily have to be provided in the heat exchange type ventilation device 100. Instead, data for controlling each of the exhaust blower 8 and the supply air blower 7 is stored in a memory (e.g., a non-volatile memory of the memory 22) of the control unit 15. Note that, similar to the first modified example, each of the exhaust blower 8 and the supply air blower 7 has multiple air volume notches set. Each air volume notch has a corresponding command voltage, and when an air volume notch is selected, the control unit 15 operates the blower at a power corresponding to that air volume notch based on the command voltage corresponding to that air volume notch.

The data for detecting the air volume as the data for controlling the exhaust blower 8 is configured in the form of a table in which the operating parameters and the air volumes are associated, and is stored in the memory of the control unit 15. Specifically, the table is data obtained in advance by examining the blowing characteristics of the exhaust blower 8 through testing, etc., and is configured with corresponding data between the operating parameters of the exhaust blower 8 and the exhaust air volume for each command voltage (i.e., each air volume notch) for each specific load point, and is configured with corresponding data between the operating parameters of the exhaust blower 8 and the exhaust air volume obtained in the same manner at many different load points. The operating parameters are, for example, the value of the drive current supplied to the motor of the exhaust blower 8 and the number of rotations of the motor. The control unit 15 controls the output of the exhaust blower 8 by referring to this table. The data for controlling the supply air blower 7 is also configured in the form of a table in which the operating parameters and the air volumes are associated, and the control unit 15 controls the output of the supply air blower 7 by referring to this table.

The load point of the exhaust fan 8 varies not only with the pressure loss of the exhaust air duct in the heat exchange type ventilation device, but also with the pressure loss of the duct connected to the indoor inlet 5a and the duct connected to the outdoor outlet 6a of the heat exchange type ventilation device. A specific example of a table for detecting the air volume is shown in FIG. 5. FIG. 5 is an example of a table at one load point of the exhaust air duct 102. The number of air volume notches of the exhaust fan 8 is n (n is an integer of 2 or more). As shown in FIG. 5, a table showing the exhaust air volume Ek and the operating parameters for the command voltage Dk of the exhaust fan 8 for each air volume notch is stored in memory. The operating parameters for the command voltage Dk are composed of the drive current xk and the rotation speed yk. k represents an integer from 1 to n. Note that the air volume notches in the leftmost column of FIG. 5 are listed for convenience and are not necessarily data included in the table.

In heat exchange operation, a command voltage Di corresponding to the air volume notch selected by the user is selected, and the control unit 15 controls the driving of the exhaust blower 8 in response to the command voltage Di to operate the exhaust blower 8. When the exhaust blower 8 is operated with the input power corresponding to the command voltage Di, the control unit 15 measures the drive current and rotation speed supplied to the motor of the exhaust blower 8, and based on the measured values, determines from all tables that the data having the closest points in both the measured drive current and rotation speed is the current operating point, regards the air volume of that operating point as the current exhaust air volume, and further regards the load point having that operating point as the current load point of the exhaust air duct 102 (during heat exchange operation).

When the operating state is switched from heat exchange operation to circulation operation, the control unit 15 again measures the drive current and rotation speed supplied to the motor of the exhaust blower 8, and based on the measurement values, determines from all tables the data having the closest points in both the measured drive current and rotation speed as the current operating point, regards the air volume at that operating point as the current exhaust air volume, and further regards the load point having that operating point as the current load point of the exhaust duct 102 (during circulation operation). Next, the control unit 15 determines a command voltage that realizes an air volume closest to the air volume during heat exchange operation at the determined load point (during circulation operation), and operates the exhaust blower 8 with power based on the determined command voltage, thereby making it possible to generate an exhaust air volume during circulation operation similar to that during heat exchange operation.

Although a specific example of a table for controlling the intake air blower 7 is not shown, it is data obtained in advance by investigating the blowing characteristics of the intake air blower 7 through testing, etc., and is composed of correspondence data between the operating parameters of the intake air blower 7 and the intake air volume for each command voltage (i.e., each air volume notch) for each specific load point, and is composed of correspondence data between the operating parameters of the intake air blower 7 and the intake air volume obtained in the same manner at a number of different load points. The operating parameters are, for example, the value of the drive current supplied to the motor of the intake air blower 7 and the motor rotation speed. In heat exchange operation, an operating parameter corresponding to the air volume notch arbitrarily selected by the user is selected, and the control unit 15 controls the drive of the intake air blower 7 in response to that command voltage to operate the intake air blower 7. When the supply air blower 7 is operated with an input power corresponding to the command voltage, the control unit 15 measures the drive current and rotation speed supplied to the motor of the supply air blower 7, and based on the measured values, determines from all tables the data having the closest point in both the measured drive current and rotation speed to be the current operating point, regards the air volume of that operating point as the current supply air volume, and further regards the load point having the operating point as the current load point of the supply air duct 101 (during heat exchange operation).

When the operating state is switched from heat exchange operation to circulation operation, the control unit 15 again measures the drive current and rotation speed supplied to the motor of the intake air blower 7, and based on the measurement values, determines from all tables the data having the closest points in both the measured drive current and rotation speed as the current operating point, regards the air volume at that operating point as the current circulation air volume, and further regards the load point having that operating point as the current load point (during circulation operation) of the circulation air duct 103. Next, the control unit 15 determines a command voltage that realizes an air volume closest to the intake air volume during heat exchange operation at the determined load point (during circulation operation), and operates the intake air blower 7 with power based on the determined command voltage, thereby making it possible to generate a circulation air volume during circulation operation with an air volume similar to the intake air volume during heat exchange operation.

In this way, the air volume detection units 14a and 14b are no longer necessary, and the configuration of the heat exchange ventilation device 100 can be simplified.

(Variation 3)
As data for controlling each of the exhaust blower 8 and the supply air blower 7, data on the operation command values in the heat exchange operation and the circulation operation may be stored in a memory in the control unit 15 (e.g., a non-volatile memory in the memory 22) instead of the data in the second modification. The data for controlling the exhaust blower 8 is configured in the form of a table in which the operation command value Gk of the exhaust blower 8 in the circulation operation is associated with the operation command value Fk of the exhaust blower 8 in the heat exchange operation for each air volume notch, as shown in FIG. 6. The operation command value Fk and the operation command value Gk are set so that the larger the air volume notch k, the larger the operation command value Fk and the operation command value Gk are. At each air volume notch k, the operation command value Gk is larger than the operation command value Fk. Note that the air volume notches in the leftmost column of FIG. 6 are listed for convenience and are not necessarily data included in the table.

In heat exchange operation, a certain operation command value Fi is selected, and the control unit 15 transmits an operation control signal corresponding to the operation command value Fi to the exhaust blower 8. When the operation state is switched from heat exchange operation to circulation operation, the control unit 15 obtains an operation command value Gi corresponding to the operation command value Fi from the table. The control unit 15 then transmits an operation control signal corresponding to the operation command value Gj to the exhaust blower 8. In heat exchange operation, the exhaust blower 8 operates according to the operation command value Fi, and in circulation operation, it operates according to the operation command value Gi. Therefore, the output of the exhaust blower 8 in circulation operation is greater than in heat exchange operation.

The operation command value Gi may be determined so that the exhaust air volume during circulation operation is equal to the exhaust air volume during heat exchange operation, but this is not necessarily required. It is sufficient that the operation command value Gi is set so that the output of the exhaust fan 8 during circulation operation is greater than that during heat exchange operation.

Similarly, the data for controlling the supply air blower 7 is configured in the form of a table in which the operation command value of the supply air blower 7 in heat exchange operation and the operation command value of the supply air blower 7 in circulation operation are associated with each air volume notch. When the control unit 15 switches the operation state from heat exchange operation to circulation operation, it refers to the table, selects the operation command value for circulation operation that corresponds to the operation command value selected in heat exchange operation, and sends the corresponding operation control signal to the supply air blower 7. The operation command value for circulation operation that corresponds to each operation command value for heat exchange operation may be determined so that the circulation air volume is equal to the supply air volume, but this is not necessarily required. It is desirable to set the operation command value so that the output of the supply air blower 7 in circulation operation is greater than in heat exchange operation.

The tables for controlling the exhaust blower 8 and the intake blower 7 may hold the change amount from the operation command value in heat exchange operation, rather than the operation command value in circulation operation, in correspondence with the operation command value in heat exchange operation. The control unit 15 can also refer to the table to determine the circulation operation command value for each blower in circulation operation by adding the corresponding change amount to the operation command value for the blower in heat exchange operation.

(Variation 4)
In the heat exchange type ventilation device 100, the circulation air volume during circulation operation may be set according to the detection result of the air pollution level detection unit 13. In this case, the air volume detection unit 14b does not need to be provided. Also, the circulation air volume does not need to be the same as the supply air volume.

For example, as shown in FIG. 7, data for controlling the air supply blower 7 is stored in a memory in the control unit 15 (e.g., the non-volatile memory of the memory 22). This data is in the form of a table in which thresholds A'1 to A'n relating to the amount of detected substance detected by the air pollution level detection unit 13 correspond to operation command values H1 to Hn for the air supply blower 7. n is an integer of 2 or more. The thresholds A'1 to A'n increase in this order, and are set so that the higher the threshold, the higher the corresponding operation command value H1 to Hn for the air supply blower 7.

When the amount of detected substances detected by the air pollution level detection unit 13 is less than the threshold A'1, the heat exchange type ventilation device 100 operates in heat exchange operation. When the control unit 15 determines that the amount of detected substances is equal to or greater than the threshold A'1, it controls the operation state to be switched from heat exchange operation to circulation operation. In circulation operation, when the control unit 15 determines that the amount of detected substances is in the range of equal to or greater than the threshold A'k and less than A'(k+1), it transmits an operation command value Hk corresponding to the threshold A'k to the supply air blower 7. In other words, the fourth modification is configured to increase the amount of circulation air as the amount of detected substances in the room increases. Even in circulation operation, when the amount of detected substances is small, the circulation air volume does not need to be increased more than necessary, so the rotation speed of the supply air blower 7 can be suppressed, making it possible to reduce noise and power consumption. The smaller of the operation command values H1 to Hn, for example, the minimum operation command value H1, may be the same as the operation command value of the supply air blower 7 during heat exchange operation.

Modification 4 can be applied to any of modifications 1 to 3. When modification 4 is applied to each of

modifications

2 and 3, exhaust fan 8 is controlled by the operation command value shown in the table of FIG. 5 or FIG. 6, and intake fan 7 is controlled by the operation command value shown in the table shown in FIG. 7.

(Variation 5)
As shown in FIG. 8, the table according to the fourth modification may further include operation command values J1 to Jn for the exhaust fan 8 corresponding to each threshold value. In this case, the air volume detection unit 14a may not be provided. The operation command values J1 to Jn are set so that the larger the threshold value, the larger the corresponding operation command values J1 to Jn. In the circulation operation, when the control unit 15 determines that the amount of the detected substance detected by the air pollution level detection unit 13 is in the range of the threshold value A'k or more and less than A'(k+1), the control unit 15 transmits the operation command value Jk corresponding to the threshold value A'k to the exhaust fan 8. In other words, as the amount of the detected substance in the room increases, the exhaust air volume also increases. The operation command values J1 to Jn are set so as to be larger than the operation command values during the heat exchange operation.

In addition to discretely adjusting the output of each blower by referring to the table in the fourth and fifth variations, the control unit 15 may be configured to continuously adjust the output of each blower according to the amount of detected substance detected by the air pollution level detection unit 13.

(Variation 6)
In the heat exchange type ventilation device 100, when the control unit 15 switches the operating state from heat exchange operation to circulation operation, the output of the supply air blower 7 may be continued without being changed. Therefore, the air volume detection unit 14b for detecting the supply air volume may not be provided. This modification 6 is applicable to any of modifications 1 to 3. When modification 6 is applied to each of

modifications

2 and 3, the table for controlling the supply air blower 7 becomes unnecessary.

(Variation 7)
In the sixth modified example, the air volume detection unit 14a may not be provided. The control unit 15 may be simply configured to set the operation command value for the exhaust blower 8 in the circulation operation to a value obtained by adding a certain fixed value to the operation command value for the exhaust blower 8 in the heat exchange operation, and change the output of the exhaust blower 8. A table for controlling the exhaust blower 8 is also not required. The output of the exhaust blower 8 in the circulation operation is greater than that in the heat exchange operation, but the exhaust air volume in the circulation operation does not need to be the same as the exhaust air volume in the heat exchange operation.

(Variation 8)
The operating state of the heat exchange type ventilation device 100 may be switched by the user operating an operation switch on a remote control or the like, regardless of the detection result of the air pollution level detection unit 13. The control unit 15 receives a switching command from the operation switch operated by the user, and switches between heat exchange operation and circulation operation. The control unit 15 may inform the user of indoor air pollution, for example by notifying the operation switch when the amount detected by the air pollution level detection unit 13 becomes equal to or greater than a certain reference value, i.e., threshold value A'. Alternatively, the air pollution level detection unit 13 may not be provided in the heat exchange type ventilation device 100. The user can recognize indoor air pollution by another means. This modification 8 can be applied to any of modifications 1 to 7.
(Variation 9)
As shown in Fig. 9, a heat exchange type ventilator 100a according to the ninth modification is configured by further providing an air pollution level detection unit 16 for detecting the pollution level of the outside air in the heat exchange type ventilator 100. The amount of a specific pollutant contained in the air taken in from the outdoor air inlet 3a, for example, the concentration of the substance in the air, is detected as the pollution level of the outside air. An example of the air pollution level detection unit 16 is an air quality sensor. The air pollution level detection unit 16 is provided in the supply air duct 101 upstream of the heat exchange element 2, for example, inside the connection unit 3.

The control unit 15 controls the opening and closing of the intake air shutter 11 based on the detection results from the air pollution level detection unit 16. If the control unit 15 determines that the concentration of pollutants in the outside air received from the air pollution level detection unit 13 is equal to or higher than a certain reference value, it closes the intake air shutter 11 regardless of the operating state of the heat exchange type ventilation device 100a. If the control unit 15 determines that the concentration of pollutants in the outside air is lower than a certain reference value, the control unit 15 opens the intake air shutter 11 in heat exchange operation and closes it in circulation operation. In this way, it is possible to prevent outside air from being taken in if the outside air is polluted during heat exchange operation. This variant 9 can be applied to any of variants 1 to 8.

(Variation 10)
As shown in FIG. 10, the heat exchange type ventilation device 100b according to the modification 10 is configured by further providing

filters

18 and 19 to the heat exchange type ventilation device 100. The

filters

18 and 19 are provided at the upstream inlets of the exhaust air duct 102 and the supply air duct 101 in the heat exchange element 2. The

filters

18 and 19 capture dust, pollen, fine particulate matter, etc., both indoors and outdoors, and prevent clogging of the heat exchange element 2. In particular, the filter 19 also prevents these substances from entering the room. In this case, it is preferable that the air purifying unit 12 is a filter that captures substances that are not captured by the filter 18, that is, substances that do not cause clogging of the heat exchange element 2 even if they pass through the heat exchange element 2 (for example, odorous substances or viruses in the room) from the air. This modification 10 can be applied to any of the modifications 1 to 9.

Embodiment 2.
11 is a schematic diagram of a heat exchanger type ventilation device 200 according to embodiment 2. The configuration and operation of the heat exchanger type ventilation device 200 will be described below, but those not described are assumed to be the same or substantially the same as the configuration and operation of the heat exchanger type ventilation device 100 according to embodiment 1.

The heat exchange type ventilation device 200 does not have the intake shutter 11 of the heat exchange type ventilation device 100. Therefore, in circulation operation as well as heat exchange operation, as shown in FIG. 11, air flows from the outdoor intake port 3a to the indoor exhaust port 4a through the intake air duct 101 by the operation of the intake air blower 7. The air flowing through the intake air duct 101 exchanges heat with the air flowing through the exhaust air duct 102 by the heat exchange element 2.

The heat exchange type ventilation device 200 also includes an air volume detection unit 14c instead of the air volume detection unit 14b. The air volume detection unit 14c is provided in the supply air duct 101 upstream of the circulation air duct opening 9, and detects the volume of air sucked in from the outdoor air inlet port 3a. The air volume detection unit 14c is, for example, a differential pressure sensor, and is provided inside the connection unit 3. The air volume detection unit 14c outputs a value indicating the volume of air as a detection result to the control unit 15. The control unit 15 receives the detection result from the air volume detection unit 14c, and adjusts the output of the supply air blower 7 according to the detection result. In the second embodiment, the volume of air sucked in from the indoor air inlet port 5a is called the "supply air volume", and the volume of air flowing through the circulation air duct opening 9 is called the "circulation air volume". Therefore, in the second embodiment, the volume of air supplied from the indoor discharge port 4a to the room is equal to the supply air volume in the heat exchange operation, and is equal to the supply air volume plus the circulation air volume in the circulation operation.

The method of controlling the operation of the heat exchange type ventilation device 200 is the same as that of the heat exchange type ventilation device 100 of the first embodiment. However, in FIG. 3, "supply air volume detection value B" is replaced with the supply air volume detection value indicating the supply air volume detected by the air volume detection unit 14c in heat exchange operation, and "circulation air volume detection value B'" is replaced with the supply air volume detection value indicating the supply air volume detected by the air volume detection unit 14c in circulation operation. Therefore, the exhaust air volume in circulation operation is equal to the exhaust air volume in heat exchange operation, and the supply air volume in circulation operation is also equal to the supply air volume in heat exchange operation. At this time, when the operating state is switched from heat exchange operation to circulation operation, the exhaust fan 8 and the supply air fan 7 are controlled to increase their output, respectively.

The heat exchange ventilation device 200 configured in this manner provides the following effects:

When the operating state is switched from heat exchange operation to circulation operation, the exhaust air volume decreases unless the output of the exhaust blower 8 and the supply air blower 7 is changed, as in the heat exchange type ventilation device 100. Therefore, when the operating state is switched from heat exchange operation to circulation operation, the control unit 15 controls the exhaust blower 8 to increase its output. Therefore, even when air purification is performed by circulation operation, an appropriate amount of air can be ensured to be exhausted to the outside. As a result, indoor pollutants that are not removed by the air purification unit 12 can be quickly discharged to the outside.

Even during circulation operation when the circulation air duct opening 9 is open, the heat exchange element 2 exchanges heat between the air passing through the supply air duct 101 and the air passing through the exhaust air duct 102. This reduces the loss of thermal energy inside the room.

Furthermore, the control unit 15 controls the output of the exhaust blower 8 and the supply blower 7 so that the exhaust air volume is equal in the circulation operation and the heat exchange operation, and the supply air volume is also equal in the circulation operation and the heat exchange operation. Therefore, the difference between the air volume of the air sucked in from the indoor intake port 5a and the air volume of the air supplied from the indoor discharge port 4a in the circulation operation is equal to the difference between the air volume of the air sucked in from the indoor intake port 5a and the air volume of the air supplied from the indoor discharge port 4a in the heat exchange operation. Therefore, even if the operation state is switched from the heat exchange operation to the circulation operation, the change in the pressure inside the room can be suppressed. Note that, when the exhaust air volume and the supply air volume are the same in the heat exchange operation, the air volume of the air sucked in from the indoor intake port 5a and the air volume of the air supplied from the indoor discharge port 4a are the same in the circulation operation.

Next, we will explain a modified example of the heat exchange ventilation device 200.

All of the modified examples 1 to 10 described in the first embodiment can be applied to the heat exchange type ventilation device 200 of the second embodiment. For example, when the modified example 1 is applied to the second embodiment, in the circulation operation, the control unit 15 adjusts the output of the exhaust blower 8 to an output level at which the exhaust airflow detection value C' is closest to the exhaust airflow detection value C among the multiple adjustable output levels of the exhaust blower 8. The control unit 15 also adjusts the output of the supply air blower 7 to an output level at which the supply airflow detection value detected by the airflow detection unit 14c is closest to the supply airflow detection value detected in the heat exchange operation among the multiple adjustable output levels of the supply air blower 7. When the modified example 2 is applied to the second embodiment, a table showing the predicted value of the supply airflow in the heat exchange operation and the predicted value of the supply airflow in the circulation operation for the operation command value of the supply air blower 7 for each airflow notch is prepared as a table for controlling the supply air blower 7.

When variant 9 is applied to embodiment 2, the heat exchange type ventilation device 200 is provided with an intake air shutter 11. When the control unit 15 determines that the concentration of pollutants in the outside air received from the air pollution level detection unit 13 is equal to or higher than a certain reference value, it closes the intake air shutter 11 regardless of the operating state. When the control unit 15 determines that the concentration of pollutants in the outside air is lower than the reference value, it opens the intake air shutter 11 regardless of the operating state.

In addition to applying the modifications 1 to 10, in the heat exchange type ventilation device 200, the control unit 15 may be configured to adjust the opening of the circulation air duct damper 10 in accordance with the detection result of the air pollution level detection unit 13 during circulation operation in which the circulation air duct opening 9 is open. For example, as shown in FIG. 12, data in a table format in which threshold values A'1 to A'n relating to the amount of detected substance detected by the air pollution level detection unit 13 correspond to the opening degrees X1 to Xn of the circulation air duct damper 10 is stored in the memory of the control unit 15 (e.g., the non-volatile memory of the memory 22). The threshold values A'1 to A'n increase in this order, and are set so that the opening degrees X1 to Xn increase as the threshold value increases.

When the amount of detected substance detected by the air pollution level detection unit 13 is less than the threshold A'1, the heat exchange type ventilation device 100 operates in heat exchange operation. When the control unit 15 determines that the amount of detected substance is equal to or greater than the threshold A'1, it controls the operation state to be switched from heat exchange operation to circulation operation. In circulation operation, when the control unit 15 determines that the amount of detected substance detected by the air pollution level detection unit 13 is in the range of equal to or greater than the threshold A'k and less than A'(k+1), it controls the circulation air duct damper 10 to be opened at an opening degree Xk corresponding to the threshold A'k.

Therefore, in circulation operation, the circulation air volume is adjusted to increase when the level of pollution in the room is higher. In other words, even in circulation operation, when the pollution in the room is not very advanced, the circulation air volume is kept from being more than necessary. When switching the operating state from heat exchange operation to circulation operation, the control unit 15 increases the output of the exhaust blower 8 and the supply air blower 7 so that the exhaust air volume and the supply air volume are predetermined amounts. At this time, the opening of the circulation air duct damper 10 is suppressed, so the output of the exhaust blower 8 and the supply air blower 7 is also suppressed. This makes it possible to reduce noise and power consumption of the exhaust blower 8 and the supply air blower 7.

In addition to discretely adjusting the opening degree of the circulating air duct damper 10 by referring to the table, the control unit 15 may be configured to continuously adjust the opening degree of the circulating air duct damper 10 according to the amount of detected substance detected by the air pollution level detection unit 13.

The embodiments disclosed herein are illustrative, and components may be modified, omitted, or added to each embodiment without departing from the scope of the claims.

Reference Signs List 1 Housing, 2 Heat exchange element, 3 to 6 Connection section, 3a Outdoor intake port, 4a Indoor exhaust port, 5a Indoor intake port, 6a Outdoor exhaust port, 7 Air supply fan, 8 Exhaust fan, 9 Circulation air duct opening, 10 Circulation air duct damper, 11 Air supply shutter, 12 Air purifier, 13 Air pollution level detector, 14a, 14b Air volume detector, 15 Control section, 15a Control circuit, 100 Heat exchange type ventilation device, 101 Air supply air duct, 102 Exhaust air duct

Claims

a housing having an outdoor suction port, an indoor discharge port, an indoor suction port, and an outdoor discharge port, and having an air supply duct connecting the outdoor suction port and the indoor discharge port, and an air exhaust duct connecting the indoor suction port and the outdoor discharge port formed therein;
a heat exchange element provided inside the housing and performing heat exchange between air passing through the intake air passage and air passing through the exhaust air passage;
a supply air blower provided in the supply air duct to generate an air flow from the outdoor inlet to the indoor outlet, and a exhaust air blower provided in the exhaust air duct to generate an air flow from the indoor inlet to the outdoor outlet,
a circulation air duct opening that connects a portion of the intake air duct downstream of the heat exchange element and a portion of the exhaust air duct upstream of the heat exchange element is formed inside the housing;
The heat exchange type ventilation device further comprises:
a circulation air duct damper for opening and closing the circulation air duct opening;
An air purifying unit that purifies the air passing through the circulation air duct opening; and
a control unit that controls the exhaust fan to increase an output of the exhaust fan when the circulation air duct damper opens the circulation air duct opening;
A heat exchange type ventilation device equipped with:
an air pollution level detection unit that detects the pollution level of air taken in through the indoor air inlet,
2. The heat exchange type ventilation device according to claim 1, wherein the control unit controls the circulating air duct damper to open the circulating air duct opening based on the result detected by the air pollution level detection unit.
The heat exchange type ventilation device according to claim 1, wherein the control unit controls the air supply fan to increase the output of the air supply fan when the air circulation duct damper opens the air circulation duct opening.
The heat exchange type ventilation device according to any one of claims 1 to 3, further comprising an intake air shutter that is provided in the intake air duct upstream of the portion to which the circulation air duct opening is connected and opens and closes the intake air duct, and the control unit controls the intake air shutter to close the intake air duct when the circulation air duct damper opens the circulation air duct opening.
The heat exchange type ventilation device according to any one of claims 1 to 3, wherein when the circulating air duct damper is open, the heat exchange element exchanges heat between the air passing through the intake air duct and the air passing through the exhaust air duct.
When the circulating air duct damper is open, the heat exchange element exchanges heat between the air passing through the intake air duct and the air passing through the exhaust air duct,
3. The heat exchange type ventilation device according to claim 2, wherein the control unit is capable of adjusting an opening degree of the circulating air duct damper in accordance with the degree of pollution detected by the air pollution level detection unit while the circulating air duct damper is open.
An air volume detection unit is provided to detect the volume of air discharged from the outdoor discharge port,
The control unit is capable of changing the output of the exhaust fan to a plurality of output levels,
7. The heat exchange type ventilation device according to claim 1, wherein the control unit adjusts the output of the exhaust fan to an output level among the multiple output levels at which the air volume detected by the air volume detection unit with the circulation air duct damper opening the circulation air duct is closest to the air volume detected by the air volume detection unit with the circulation air duct damper closing the circulation air duct opening.
The control unit stores a table in which an operating parameter is associated with a value indicating an air volume associated with the operating parameter,
the operating parameters indicate a value of a drive current supplied to a motor included in either the exhaust fan or the intake fan and a rotation speed of the motor,
The air volume is a predicted value of the air volume of the airflow generated by the operation of the blower including the motor,
7. The heat exchange type ventilation device according to claim 1, wherein the control unit adjusts an output of the blower including the motor by referring to the table.
The heat exchange type ventilation device according to any one of claims 1 to 8, wherein the air purification section removes at least one of carbon monoxide, carbon dioxide, volatile organic compounds, fine particulate matter, dust, pollen, viruses, and odorous substances from the air flowing through the circulation air duct opening.