Air conditioning device

Abstract

[Problem] In an air conditioning device having a heat exchanger, to suppress a deterioration over time in the performance of the heat exchanger. [Solution] A heating, ventilation, and air conditioning (HVAC) system 1 includes: a heat exchanger 3 for exchanging heat between exhaust air to be discharged to the outside of a vehicle cabin and outside air to be introduced into the vehicle cabin; an exhaust air passage 5A for guiding the exhaust air to an exhaust air introduction port 3A of the heat exchanger 3; an outside air passage 5B for guiding the outside air to an outside air introduction port 3B of the heat exchanger 3; a return air passage 5C for circulating return air within the vehicle cabin while bypassing the heat exchanger 3; and a housing 5 in which a discharge port 5D for discharging the exhaust air that has passed through the heat exchanger 3 to the outside of the vehicle cabin is formed. Furthermore, the HVAC system 1 additionally includes: a filter 7 which is disposed across at least the exhaust air passage 5A and the outside air passage 5B among the exhaust air passage 5A, the outside air passage 5B, and the return air passage 5C, on the upstream side of the exhaust air introduction port 3A and the outside air introduction port 3B of the heat exchanger 3; and a damper 9 for adjusting the amount of outside air introduced into the vehicle cabin by changing the opening ratios of the outside air passage 5B and the return air passage 5C on the upstream side of the filter 7.

Description

air conditioning equipment

[0001] The present invention relates to an air conditioning apparatus for conditioning the air inside a vehicle cabin.

[0002] Vehicles such as automobiles are equipped with air conditioning devices such as heating, ventilation, and air conditioning (HVAC) systems that perform heating, ventilation, and air conditioning to keep the interior of the vehicle comfortable. As described in Japanese Patent Laid-Open Publication No. 2016-155516 (Patent Document 1), the air conditioning device has a heat exchanger that improves energy-saving performance by exchanging heat between outside air introduced into the vehicle cabin and inside air discharged to the outside of the vehicle cabin during ventilation.

[0003] Japanese Patent Application Laid-Open No. 2016-155516

[0004] However, in the air conditioning device described in Patent Document 1, outside air and inside air containing foreign matter such as dust were introduced directly into the heat exchanger, which could cause the heat exchanger to become clogged over time, resulting in a decrease in the performance of the heat exchanger.

[0005] Therefore, an object of the present invention is to suppress deterioration in performance of a heat exchanger over time in an air conditioning apparatus having a heat exchanger.

[0006] The air conditioner includes a heat exchanger that exchanges heat between exhaust gas discharged from inside the vehicle cabin to outside the vehicle cabin and outside air introduced from outside the vehicle cabin into the vehicle cabin, and a housing that has an exhaust passage that guides the exhaust gas to an exhaust inlet of the heat exchanger, an outside air passage that guides outside air to an outside air inlet of the heat exchanger, a return air passage that circulates return air from the vehicle cabin while bypassing the heat exchanger, and an exhaust port that discharges the exhaust gas that has passed through the heat exchanger to outside the vehicle cabin. In addition to the heat exchanger and the housing, the air conditioner also includes a filter that is arranged throughout the exhaust passage, the outside air passage, and the return air passage upstream of the exhaust gas inlet and the outside air inlet of the heat exchanger, and a damper that is arranged upstream of the filter and that adjusts the amount of outside air introduced into the vehicle cabin by changing the opening ratio of the outside air passage and the return air passage.

[0007] According to the present invention, in an air conditioning apparatus having a heat exchanger, deterioration in performance of the heat exchanger over time can be suppressed.

[0008] FIG. 1 is a schematic diagram showing an example of an HVAC (Heating, Ventilation and Air Conditioning) system; FIG. 2 is a schematic perspective view showing an example of a static heat exchanger; FIG. 3 is an explanatory diagram of the operation of an outside air introduction mode in summer; FIG. 4 is an explanatory diagram of the operation of a mixed mode in summer; FIG. 5 is an explanatory diagram of the operation of a circulation mode in summer; FIG. 6 is an explanatory diagram of the operation of an outside air introduction mode in winter; FIG. 7 is an explanatory diagram of the operation of a mixed mode in winter; and FIG. 8 is an explanatory diagram of the operation of a circulation mode in winter.

[0009] Hereinafter, an embodiment for carrying out the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of an HVAC system 1 to which the present embodiment can be applied. Please note that the HVAC system 1 described below is merely an example to which the present embodiment can be applied, and should not be construed as being limited to this configuration. Therefore, it goes without saying that a person skilled in the art can freely change and modify the present embodiment within the technical scope. The HVAC system 1 is an example of an air conditioning device.

[0010] The HVAC system 1 includes a heat exchanger 3 that exchanges heat between exhaust air discharged from inside the vehicle cabin to outside the vehicle cabin and outside air introduced from outside the vehicle cabin into the vehicle cabin, a housing 5 that houses the heat exchanger 3, and a filter 7 that removes foreign matter such as dust contained in the exhaust air, outside air, and return air from inside the vehicle cabin.

[0011] The heat exchanger 3 may be, for example, a total heat exchanger that exchanges and recovers the total heat of the air conditioning energy lost through ventilation, i.e., sensible heat (temperature) and latent heat (humidity). If the heat exchanger 3 is a total heat exchanger, temperature and humidity are exchanged between the exhaust air discharged from the interior of the vehicle to the exterior of the vehicle and the outside air introduced from the exterior of the vehicle into the vehicle, so that the outside air is heated by the exhaust air in winter and cooled by the exhaust air in summer, thereby reducing the air conditioning load. The following description will be given assuming a stationary heat exchanger 3, but a rotary heat exchanger 3 may also be used, as described below.

[0012] As shown in FIG. 2 , the heat exchanger 3 is constructed by stacking, in one direction, a partition member 3C formed by coating a fibrous substrate with a polymer adsorbent and a corrugated spacing member 3D. The heat exchanger 3 is constructed so that the flow direction of the outside air and the flow direction of the exhaust air alternately differ by 90° between each layer. Therefore, the exhaust air inlet 3A and the outside air inlet 3B of the heat exchanger 3 are formed on adjacent side surfaces, respectively. The polymer adsorbent coated on the partition member 3C is composed of, for example, crosslinked sodium polyacrylate. Such polymer adsorbents have a high moisture absorption rate, can desorb (release) retained moisture at low temperatures, and can retain moisture for a long time. Therefore, the partition member 3C formed by coating a fibrous substrate with a polymer adsorbent has good heat conductivity and moisture permeability.

[0013] The housing 5 is provided at predetermined locations with an exhaust passage 5A that guides exhaust air to the exhaust inlet 3A of the heat exchanger 3, an outside air passage 5B that guides outside air to the outside air inlet 3B of the heat exchanger 3, a return air passage 5C that circulates return air from the vehicle cabin while bypassing the heat exchanger 3, and an exhaust port 5D equipped with a rubber shutter SH that discharges exhaust air that has passed through the heat exchanger 3 to the outside of the vehicle cabin. Partitions are formed between the exhaust passage 5A, the outside air passage 5B, and the return air passage 5C, and between the heat exchanger 3 and the return air passage 5C, to prevent the exhaust air, outside air, and return air flowing through each passage from mixing. Furthermore, a return air inlet 5E is formed at a predetermined location upstream of the return air passage 5C in the housing 5, to introduce return air from the vehicle cabin into the return air passage 5C.

[0014] A damper 9 that adjusts the amount of outside air introduced into the vehicle cabin by changing the opening rates of the outside air passage 5B and the return air passage 5C in conjunction with each other is disposed (housed) near the upstream end of a partition wall that separates the outside air passage 5B and the return air passage 5C in the housing 5. The damper 9 changes the opening rates of the outside air passage 5B and the return air passage 5C continuously or in stages by means of an actuator (not shown), such as a stepping motor, between an outside air introduction state (the state shown in FIG. 1 ) in which outside air is introduced and a return air circulation state in which return air is circulated.

[0015] In the housing 5, the downstream side of the heat exchanger 3 and the downstream side of the return air passage 5C join together to form a narrow passage 5F, and an electric fan 11 is disposed downstream of this narrow passage 5F to send supply air made up of at least one of the exhaust air that has passed through the heat exchanger 3 and the return air that has passed through the return air passage 5C to the downstream side. The fan 11 may be, for example, an electric blower fan.

[0016] An air supply passage 5G is formed downstream of the fan 11, through which the supply air sent out by the fan 11 is introduced into the vehicle cabin. The air supply passage 5G, located downstream of the fan 11, is provided with an evaporator 13, which constitutes a refrigerant circuit of the HVAC system 1. A portion of the air supply passage 5G located downstream of the evaporator 13 is divided into two sections along the supply air flow direction. In one section, for example, in the illustrated example, a heater core 15 is located at the bottom, which heats the supply air that has passed through the evaporator 13 and been cooled to nearly 0°C. An air mix door 17 is located upstream of the heater core 15, which adjusts the temperature of the supply air introduced into the vehicle cabin by increasing or decreasing the flow rate of the supply air passing through the heater core 15. The air mix door 17 is operated by an actuator, such as a stepping motor (not shown), and is configured to adjust the flow rate of the supply air passing through the heater core 15 continuously or in steps from approximately 0% to approximately 100%.

[0017] 1, a member BH indicated by a two-dot chain line is a bulkhead that separates the front body from the passenger compartment (the same applies to other figures). Therefore, the left side of the bulkhead BH represents the outside of the passenger compartment, and the right side of the bulkhead BH represents the inside of the passenger compartment.

[0018] The filter 7 is a member that removes foreign matter such as dust contained in the exhaust air and outside air introduced into the heat exchanger 3, and is replaceably attached to the HVAC system 1. That is, the filter 7 removes foreign matter as the HVAC system 1 operates, and therefore gradually becomes clogged over time. For this reason, the filter 7 is easily replaceable in the HVAC system 1. The filter 7 is disposed upstream of the exhaust air inlet 3A and outside air inlet 3B of the heat exchanger 3, throughout the exhaust passage 5A, outside air passage 5B, and return air passage 5C of the housing 5.

[0019] Next, the operation of the HVAC system 1 will be described. In summer, when air conditioning is used, when the driver or passenger of the vehicle switches the air conditioning system to the outside air intake mode, the damper 9 operates to close the return air passage 5C, as shown in FIG. 3 . This causes the opening rate of the outside air passage 5B to be approximately 100%, while the opening rate of the return air passage 5C to be approximately 0%. In the summer outside air intake mode, as the fan 11 operates, outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in that order, and then passes through the narrow passage 5F and the fan 11 located downstream thereof to become supply air and be introduced into the supply air passage 5G. In addition, in the summer outside air intake mode, the air mix door 17 adjusts the flow rate of supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the temperature inside the vehicle cabin closer to the set temperature.

[0020] When outside air is introduced into the vehicle cabin, the pressure inside the vehicle cabin rises, and the pressure of the inside air becomes higher than the pressure of the outside air. This pressure difference is used to introduce exhaust gas into the exhaust passage 5A via an exhaust passage (not shown). The exhaust gas introduced into the exhaust passage 5A passes through the filter 7 and the heat exchanger 3, and then pushes open a shutter SH of an exhaust port 5D formed in the housing 5, and is then discharged outside the vehicle cabin. When the exhaust gas, which is cooler than the outside air, passes through the heat exchanger 3, the outside air is cooled by the heat exchanger 3, thereby reducing the air conditioning load.

[0021] In this summer outside air introduction mode, outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 located downstream of the filter 7. This eliminates or significantly reduces the amount of foreign matter introduced into the heat exchanger 3, preventing clogging of the heat exchanger 3 and thereby preventing deterioration of the heat exchanger's performance over time.

[0022] In summer, when air conditioning is used, if the driver or passenger of the vehicle switches the air conditioning system to the mixed mode, as shown in FIG. 4 , the damper 9 operates to be intermediate between the outside air introduction mode and the return air circulation mode, and the opening rates of the outside air passage 5B and the return air passage 5C are approximately 50%. In the summer mixed mode, as the fan 11 operates, outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and return air from the passenger compartment passes through the return air passage 5C and the filter 7 in this order. The outside air and return air then pass through the narrow passage 5F and the fan 11 located downstream of the outside air and are introduced into the supply air passage 5G as supply air. In the summer mixed mode, as in the summer outside air introduction mode, the air mix door 17 adjusts the flow rate of supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the passenger compartment temperature closer to the set temperature.

[0023] When outside air is introduced into the vehicle cabin, the pressure inside the vehicle cabin rises, and the pressure of the inside air becomes higher than the pressure of the outside air. This pressure difference is used to introduce exhaust gas into the exhaust passage 5A via an exhaust passage (not shown). The exhaust gas introduced into the exhaust passage 5A passes through the filter 7 and the heat exchanger 3, and then pushes open a shutter SH of an exhaust port 5D formed in the housing 5, and is then discharged outside the vehicle cabin. When the exhaust gas, which is cooler than the outside air, passes through the heat exchanger 3, the outside air is cooled by the heat exchanger 3, thereby reducing the air conditioning load.

[0024] In this summer mixed mode, outside air passes through the filter 7 to remove foreign matter before being introduced into the heat exchanger 3 located downstream of the filter 7. This eliminates or significantly reduces the amount of foreign matter introduced into the heat exchanger 3, preventing the heat exchanger 3 from becoming clogged, thereby preventing the performance of the heat exchanger from deteriorating over time. Furthermore, the return air introduced into the return air passage 5C has foreign matter removed by the filter 7 before being returned to the vehicle cabin via the narrow passage 5F, the fan 11, and the supply air passage 5G. Therefore, even if foreign matter such as dust gets mixed into the inside air of the vehicle cabin, the cleanliness of the vehicle cabin can be maintained.

[0025] In the summer when air conditioning is used, when the driver or passenger of the vehicle switches the air conditioning system to circulation mode, the damper 9 operates to close the outside air passage 5B, causing the opening rate of the outside air passage 5B to be approximately 0%, while the opening rate of the return air passage 5C to be approximately 100%, as shown in Figure 5. In the summer circulation mode, as the fan 11 operates, the return air passes through the filter 7, passes through the narrow passage 5F located downstream thereof, and then passes through the fan 11 to become supply air and is introduced into the supply air passage 5G. In addition, in the summer circulation mode, the air mix door 17 adjusts the flow rate of the supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the temperature inside the vehicle cabin closer to the set temperature.

[0026] In the circulation mode in summer, heat exchange between the exhaust air and the outside air is not performed by the heat exchanger 3, but the return air from the passenger compartment is returned to the passenger compartment after foreign matter has been removed by the filter 7, so the cleanliness of the passenger compartment can be maintained.

[0027] In winter, when the vehicle driver or passengers switch the air conditioning system to the fresh air intake mode, the damper 9 operates to close the return air passage 5C, as shown in Figure 6, so that the opening rate of the fresh air passage 5B is approximately 100%, while the opening rate of the return air passage 5C is approximately 0%. In the winter fresh air intake mode, as the fan 11 operates, fresh air passes through the fresh air passage 5B, the filter 7, and the heat exchanger 3 in that order, and then passes through the narrow passage 5F and the fan 11 located downstream thereof to become supply air and be introduced into the supply air passage 5G. In the summer fresh air intake mode, the air mix door 17 adjusts the flow rate of supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the temperature inside the vehicle cabin closer to the set temperature.

[0028] When outside air is introduced into the vehicle cabin, the pressure inside the vehicle cabin rises, and the pressure of the inside air becomes higher than the pressure of the outside air. This pressure difference is used to introduce exhaust gas into the exhaust passage 5A via an exhaust passage (not shown). The exhaust gas introduced into the exhaust passage 5A passes through the filter 7 and the heat exchanger 3, and then pushes open a shutter SH of an exhaust port 5D formed in the housing 5, and is then discharged outside the vehicle cabin. When the exhaust gas, which is hotter than the outside air, passes through the heat exchanger 3, the outside air is warmed by the heat exchanger 3, thereby reducing the air conditioning load.

[0029] In this winter outside air introduction mode, outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 located downstream of the filter 7. This eliminates or significantly reduces the amount of foreign matter introduced into the heat exchanger 3, preventing clogging of the heat exchanger 3 and thereby preventing deterioration of the heat exchanger's performance over time.

[0030] In winter, when the vehicle driver or passengers switch the air conditioning system to the mixed mode, as shown in FIG. 7 , the damper 9 operates to be intermediate between the outside air introduction mode and the return air circulation mode, and the opening rates of the outside air passage 5B and the return air passage 5C are approximately 50%. In the winter mixed mode, as the fan 11 operates, outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and return air from the passenger compartment passes through the return air passage 5C and the filter 7 in this order. The outside air and return air then pass through the narrow passage 5F and the fan 11 located downstream of the outside air and are introduced into the supply air passage 5G as supply air. In the winter mixed mode, as in the winter outside air introduction mode, the air mix door 17 adjusts the flow rate of supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the passenger compartment temperature closer to the set temperature.

[0031] When outside air is introduced into the vehicle cabin, the pressure inside the vehicle cabin rises, and the pressure of the inside air becomes higher than the pressure of the outside air. This pressure difference is used to introduce exhaust gas into the exhaust passage 5A via an exhaust passage (not shown). The exhaust gas introduced into the exhaust passage 5A passes through the filter 7 and the heat exchanger 3, and then pushes open a shutter SH of an exhaust port 5D formed in the housing 5, and is then discharged outside the vehicle cabin. When the exhaust gas, which is hotter than the outside air, passes through the heat exchanger 3, the outside air is warmed by the heat exchanger 3, thereby reducing the air conditioning load.

[0032] In such a winter mixed mode, outside air passes through the filter 7 to remove foreign matter before being introduced into the heat exchanger 3 located downstream of the filter 7. As a result, foreign matter introduced into the heat exchanger 3 is eliminated or significantly reduced, preventing the heat exchanger 3 from becoming clogged, thereby preventing the performance of the heat exchanger from deteriorating over time. Furthermore, the return air introduced into the return air passage 5C has foreign matter removed by the filter 7 before being returned to the vehicle cabin via the narrow passage 5F, the fan 11, and the supply air passage 5G. Therefore, even if foreign matter such as dust gets mixed into the inside air of the vehicle cabin, the cleanliness of the vehicle cabin can be maintained.

[0033] In winter, when heating is used, if the driver or passenger of the vehicle switches the air conditioning system to circulation mode, the damper 9 operates to close the outside air passage 5B, causing the opening rate of the outside air passage 5B to be approximately 0%, while the opening rate of the return air passage 5C to be approximately 100%, as shown in Fig. 8. In the winter circulation mode, as the fan 11 operates, the return air passes through the filter 7, passes through the narrow passage 5F located downstream thereof, and then passes through the fan 11 to become supply air and is introduced into the supply air passage 5G. In addition, in the winter circulation mode, the air mix door 17 adjusts the flow rate of the supply air passing through the heater core 15 according to the set temperature of the air conditioning system, thereby bringing the temperature inside the vehicle cabin closer to the set temperature.

[0034] In the circulation mode in winter, heat exchange between the exhaust air and the outside air is not performed by the heat exchanger 3, but the return air from the passenger compartment is returned to the passenger compartment after foreign matter has been removed by the filter 7, so the cleanliness of the passenger compartment can be maintained.

[0035] As explained above, in either the summer or winter outdoor air intake mode, the mix mode, or the circulation mode, foreign matter has already been removed from the outdoor air or exhaust air introduced into the heat exchanger 3 by the filter 7 disposed upstream thereof. This prevents the heat exchanger 3 from becoming clogged over time in the HVAC system 1, thereby extending the maintenance interval, for example. Note that the filter 7 of the HVAC system 1 is typically replaced at predetermined intervals, so it is considered to be within the expected range even if foreign matter accumulates therein.

[0036] Here, we will explain the control system of the HVAC system 1. The control system of the HVAC system 1 according to the first embodiment has a concentration sensor that detects the CO2 concentration (carbon dioxide concentration) of the return air flowing through the return air passage 5C of the housing 5, and a control unit that controls the position of the damper 9 in response to an output signal from the concentration sensor. Here, the control unit may be, for example, a microcomputer incorporating an arithmetic unit, a storage device, an input / output device, a communication device, etc., or a control circuit configured with an LSI (Large Scale Integration), an IC (Integrated Circuit), resistors, capacitors, etc. (the same applies hereinafter).

[0037] The following describes an example of a damper control process that is repeatedly executed by the control unit when the mode of the air conditioning system is switched to the mixed mode or the circulation mode upon activation of the HVAC system 1. If the control unit is a microcomputer, an application program for executing the damper control process is pre-stored in a storage device.

[0038] In a first step, the control unit reads the CO2 concentration from the concentration sensor.

[0039] In the second step, the control unit determines whether the CO2 concentration read from the concentration sensor is equal to or greater than a predetermined concentration. Here, the predetermined concentration is a threshold value at which the occupant's level of alertness is considered to decrease, and may be, for example, 3000 ppm. If the control unit determines that the CO2 concentration is equal to or greater than the predetermined concentration (Yes), the control unit proceeds to the third step. On the other hand, if the control unit determines that the CO2 concentration is less than the predetermined concentration (No), the control unit terminates the damper control process for the current control cycle.

[0040] In the third step, the control unit outputs a control signal to an actuator (not shown), such as a stepping motor, that changes the position of the damper 9, thereby increasing the opening ratio of the outside air passage 5B in the housing 5 and decreasing the opening ratio of the return air passage 5C, thereby increasing the amount of outside air introduced into the vehicle cabin. After controlling the damper 9, the control unit ends the damper control process for the current control cycle.

[0041] By implementing this damper control process in the control unit, when the CO2 concentration of the return air flowing through the return air passage 5C of the housing 5, i.e., the inside air in the vehicle cabin, exceeds a predetermined concentration, the amount of outside air introduced into the vehicle cabin is increased. Therefore, the CO2 concentration in the vehicle cabin is maintained below the predetermined concentration, thereby preventing a decrease in the level of alertness of the driver and passengers. Note that when the mode is switched to the outside air introduction mode, fresh outside air is introduced into the vehicle cabin continuously or intermittently, so there is no need to control the damper 9.

[0042] The control system of the HVAC system 1 of the second embodiment has a temperature and humidity sensor that detects the temperature and humidity of the return air flowing through the return air passage 5C of the housing 5, an outside air temperature sensor that detects the outside air temperature, and a control unit that controls the position of the damper 9 in accordance with the output signals of the temperature and humidity sensor and the outside air temperature sensor.

[0043] The following describes an example of a damper control process that is repeatedly executed by the control unit when the mode of the air conditioning system is switched to the mixed mode or the circulation mode upon activation of the HVAC system 1. If the control unit is a microcomputer, an application program for executing the damper control process is pre-stored in a storage device.

[0044] In a first step, the control unit reads the temperature and humidity from the temperature and humidity sensor, and in a second step, the control unit reads the outside air temperature from the outside air temperature sensor.

[0045] In the third step, the control unit calculates the dew point temperature based on the temperature and humidity read from the temperature and humidity sensor. Specifically, the control unit calculates the dew point temperature by using a predetermined formula, a saturated water vapor pressure table, and a psychrometric chart to determine the temperature at which the water vapor pressure determined from the temperature and relative humidity of the return air flowing through the return air passage 5C of the housing 5 (i.e., the inside air in the vehicle cabin) becomes saturated water vapor.

[0046] In step 4, the control unit determines whether the dew-point temperature is equal to or higher than the outside air temperature. If the control unit determines that the dew-point temperature is equal to or higher than the outside air temperature (Yes), the control unit proceeds to step 5. On the other hand, if the control unit determines that the dew-point temperature is lower than the outside air temperature (No), the control unit ends the damper control process for this control cycle.

[0047] In the fifth step, the control unit outputs a control signal to an actuator (not shown), such as a stepping motor, that changes the position of the damper 9, thereby increasing the opening ratio of the outside air passage 5B in the housing 5 and decreasing the opening ratio of the return air passage 5C, thereby increasing the amount of outside air introduced into the vehicle cabin. After controlling the damper 9, the control unit ends the damper control process for the current control cycle.

[0048] By implementing this damper control process in the control unit, when the dew point temperature of the return air flowing through the return air passage 5C of the housing 5 (i.e., the interior air inside the vehicle cabin) becomes equal to or higher than the outside air temperature, the amount of outside air introduced into the vehicle cabin increases. Therefore, the dew point temperature inside the vehicle cabin is maintained below the outside air temperature, which can prevent, for example, condensation and fogging on the windshield. Note that when the mode is switched to the outside air introduction mode, fresh outside air is continuously or intermittently introduced into the vehicle cabin, making it difficult for condensation to form on the windshield, and therefore there is no need to control the damper 9.

[0049] Furthermore, a person skilled in the art will easily understand that new embodiments can be created by omitting parts of the technical ideas of the various above-mentioned embodiments, appropriately combining parts of the ideas with each other, or replacing parts of the ideas with well-known technology.

[0050] For example, the HVAC system 1 may be configured to be detachably attached to an inside / outside air inlet of the HVAC unit. The filter 7 is not limited to being disposed throughout the exhaust passage 5A, the outside air passage 5B, and the return air passage 5C, but may be disposed at least throughout the exhaust passage 5A and the outside air passage 5B.

[0051] 1... HVAC system (air conditioning device), 3... heat exchanger, 3A... exhaust air inlet, 3B... outside air inlet, 5... housing, 5A... exhaust passage, 5B... outside air passage, 5C... return air passage, 5D... exhaust port, 7... filter, 9... damper

Claims

1. An air conditioning apparatus comprising: a heat exchanger that exchanges heat between exhaust air discharged from inside a vehicle cabin to outside the vehicle cabin and outside air introduced into the vehicle cabin from outside the vehicle cabin; a housing in which an exhaust passage that guides the exhaust air to an exhaust inlet of the heat exchanger, an outside air passage that guides the outside air to an outside air inlet of the heat exchanger, a return air passage that circulates return air from inside the vehicle cabin while bypassing the heat exchanger, and an exhaust port that discharges the exhaust air that has passed through the heat exchanger to outside the vehicle cabin; a filter that is arranged across at least the exhaust passage and the outside air passage among the exhaust passage, the outside air passage and the return air passage, upstream of the exhaust inlet and the outside air inlet of the heat exchanger; and a damper that is arranged upstream of the filter and adjusts the amount of outside air introduced into the vehicle cabin by changing the opening rate of the outside air passage and the return air passage.

2. The air conditioning apparatus according to claim 1, wherein the heat exchanger is a total heat exchanger.

3. The air conditioning apparatus of claim 1, further comprising: a concentration sensor that detects the carbon dioxide concentration of the return air flowing through the return air passage; and a control unit configured to control the damper so that the carbon dioxide concentration detected by the concentration sensor is less than a predetermined concentration.

4. The air conditioning apparatus of claim 1, further comprising: a temperature and humidity sensor that detects the temperature and humidity of the return air flowing through the return air passage; an outside air temperature sensor that detects the outside air temperature; and a control unit configured to calculate a dew point temperature based on the temperature and humidity detected by the temperature and humidity sensor and to control the damper so that the dew point temperature is lower than the outside air temperature detected by the outside air temperature sensor.

5. The air conditioning device according to claim 1, configured to be detachably attached to an indoor / outdoor air inlet of an HVAC unit.

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