Air conditioner

Abstract

To suppress deterioration over time in the performance of a heat exchanger in an air conditioner having a 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 exhausted to the outside of a cabin and outdoor air to be introduced into the cabin; and a housing 5 in which there are formed an exhaust passage 5A for leading the exhaust air to an exhaust inlet 3A of the heat exchanger 3, an outdoor air passage 5B for leading the outdoor air to an outdoor air inlet 3B of the heat exchanger 3, a return air passage 5C for circulating return air of the cabin interior while bypassing the heat exchanger 3, and an outlet 5D for discharging the exhaust air having passed the heat exchanger 3 to the outside of the cabin. Further, the HVAC system 1 further includes a filter 7 arranged across at least the exhaust passage 5A and the outdoor air passage 5B among the exhaust passage 5A, the outdoor air passage 5B, and the return air passage 5C, upstream of the exhaust inlet 3A and the outdoor air inlet 3B of the heat exchanger 3; and a damper 9 for adjusting an amount of outdoor air introduction into the cabin by varying an opening ratio of the outdoor air passage 5B and the return air passage 5C upstream of the filter.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioner that conditions the air inside a vehicle cabin. [Background technology]

[0002] Vehicles such as automobiles are equipped with air conditioners such as HVAC (Heating, Ventilation, and Air Conditioning) systems that perform heating, ventilation, and air conditioning to keep the interior of the vehicle comfortable. As described in JP 2016-155516 A (Patent Document 1), the air conditioner has a heat exchanger that improves energy saving performance by exchanging heat between outside air introduced into the vehicle cabin and inside air exhausted to the outside of the vehicle cabin when ventilating the vehicle cabin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-155516 A Summary of the Invention [Problem to be solved by the invention]

[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 meant that the heat exchanger would become clogged over time, which could lead to 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. [Means for solving the problem]

[0006] The air conditioner includes a heat exchanger 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, and 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. In addition to the heat exchanger and the housing, the air conditioner further includes a filter that is disposed throughout 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 disposed upstream of the filter and changes the opening ratio of the outside air passage and the return air passage to adjust the amount of outside air introduced into the vehicle cabin. Effect of the Invention

[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. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an HVAC (Heating, Ventilation and Air Conditioning) system. [Diagram 2] FIG. 2 is a schematic perspective view showing an example of a static heat exchanger. [Diagram 3] FIG. 13 is an explanatory diagram of the operation of the outside air introduction mode in summer. [Figure 4] FIG. 13 is an explanatory diagram of the operation of the mixed mode in summer. [Diagram 5] FIG. 13 is an explanatory diagram of the operation of the circulation mode in summer. [Figure 6] FIG. 13 is an explanatory diagram of the operation of the outside air introduction mode in winter. [Figure 7] FIG. 13 is an explanatory diagram of the operation of the mixed mode in winter. [Figure 8] FIG. 13 is an explanatory diagram of the operation of the circulation mode in winter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of 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. It should be noted 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 the configuration. Therefore, it goes without saying that a person skilled in the art can arbitrarily 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 has 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 contains the heat exchanger 3, and a filter 7 that removes foreign matter such as dust contained in the exhaust air, the outside air, and the return air from the vehicle cabin.

[0011] The heat exchanger 3 can be, for example, a total heat exchanger that exchanges and recovers the total heat of the air conditioning energy lost by ventilation, that is, 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 inside of the vehicle cabin to the outside of the vehicle cabin and the outside air introduced from the outside of the vehicle cabin into the vehicle cabin, so that in winter the outside air is heated by the exhaust air and in summer the outside air is cooled by the exhaust air, thereby reducing the air conditioning load. In the following, a description will be given on the premise that the heat exchanger 3 is a stationary type, but as will be described later, the heat exchanger 3 may be a rotary type.

[0012] As shown in FIG. 2, the heat exchanger 3 is configured by laminating, in one direction, a partition member 3C formed by coating a fibrous base material with a polymer adsorbent and a corrugated spacing member 3D. The heat exchanger 3 is configured so that the direction in which the outside air flows and the direction in which the exhaust air flows are alternately different 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, a crosslinked sodium polyacrylate. Such a polymer adsorbent has a high rate of absorbing moisture, can desorb (release) the moisture it holds at a low temperature, and can hold moisture for a long time. Therefore, the partition member 3C formed by applying a polymer adsorbent to a fibrous base material has good heat conductivity and moisture permeability.

[0013] At a predetermined position of the housing 5, an exhaust passage 5A for leading the exhaust air to the exhaust inlet 3A of the heat exchanger 3, an outside air passage 5B for leading the outside air to the outside air inlet 3B of the heat exchanger 3, a return air passage 5C for circulating the return air from the vehicle cabin while bypassing the heat exchanger 3, and an exhaust port 5D with a rubber shutter SH for discharging the exhaust air that has passed through the heat exchanger 3 to the outside of the vehicle cabin are formed. Here, partition walls 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, the outside air, and the return air flowing through each passage from mixing. Furthermore, at a predetermined position upstream of the return air passage 5C of the housing 5, a return air inlet 5E for leading the return air from the vehicle cabin to the return air passage 5C is formed.

[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 stepwise between an outside air introduction state (state shown in FIG. 1) in which outside air is introduced and a return air circulation state in which return air is circulated, for example, by an actuator (not shown) such as a stepping motor.

[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 consisting 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 to introduce the supply air sent out by the fan 11 into the vehicle interior. An evaporator 13 constituting a refrigerant circuit of the HVAC system 1 is disposed in the air supply passage 5G located downstream of the fan 11. A part of the air supply passage 5G located downstream of the evaporator 13 is divided into two along the direction in which the supply air flows, and a heater core 15 is disposed on one side, for example, on the lower side in the illustrated example, for heating the supply air cooled to nearly 0°C by passing through the evaporator 13. Furthermore, an air mix door 17 is disposed upstream of the heater core 15 to adjust the temperature of the supply air introduced into the vehicle interior by increasing or decreasing the flow rate of the supply air passing through the heater core 15. Here, the air mix door 17 is configured to be operated by an actuator such as a stepping motor (not shown) and to be able to adjust the flow rate of the supply air passing through the heater core 15 continuously or stepwise 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 (as in other drawings). 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 so becomes gradually 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 the outside air inlet 3B of the heat exchanger 3, throughout the exhaust passage 5A, the outside air passage 5B, and the return air passage 5C of the housing 5.

[0019] Next, the operation of the HVAC system 1 will be described. In summer, when cooling is used, when the driver or passenger of the vehicle switches the mode of the air conditioning system to the outside air introduction mode, the damper 9 operates to close the return air passage 5C, so that the opening rate of the outside air passage 5B becomes approximately 100%, while the opening rate of the return air passage 5C becomes approximately 0%, as shown in Fig. 3. In the outside air introduction mode in summer, the fan 11 operates, and the outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and then passes through the narrow passage 5F and the fan 11 located downstream of them to become supply air and is introduced into the supply air passage 5G. In addition, in the outside air introduction mode in summer, 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, so that the temperature inside the vehicle cabin approaches 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, and this pressure difference is used to introduce the exhaust gas into the exhaust passage 5A through 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 the exhaust port 5D formed in the housing 5, and is discharged outside the vehicle cabin. When the exhaust gas, which is at a lower temperature 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 such an outside air introduction mode in summer, outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 disposed downstream of the filter 7. As a result, no foreign matter is introduced into the heat exchanger 3 or a significant reduction is achieved, and the progression of clogging of the heat exchanger 3 is suppressed, thereby making it possible to suppress deterioration of the performance of the heat exchanger over time.

[0022] In summer, when cooling is used, when the driver or passenger of the vehicle switches the mode of the air conditioning system to the mixed mode, the damper 9 operates to be in the middle position between the outside air introduction state and the return air circulation state, and the opening ratio of the outside air passage 5B and the return air passage 5C is approximately 50%, as shown in FIG. 4. In the mixed mode in summer, the outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and the return air from the passenger compartment passes through the return air passage 5C and the filter 7 in this order, as the fan 11 operates. Then, the outside air and the return air pass through the narrow passage 5F and the fan 11 located downstream thereof, and are introduced into the supply air passage 5G as supply air. In the mixed mode in summer, 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, as in the outside air introduction mode in summer, to bring the temperature inside the passenger compartment 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, and this pressure difference is used to introduce the exhaust gas into the exhaust passage 5A through 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 the exhaust port 5D formed in the housing 5, and is discharged outside the vehicle cabin. When the exhaust gas, which is at a lower temperature 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 such a summer mixed mode, the outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 arranged downstream of the filter 7. Therefore, the foreign matter introduced into the heat exchanger 3 is eliminated or significantly reduced, and the progress of clogging of the heat exchanger 3 is suppressed, thereby making it possible to suppress the deterioration of the performance of the heat exchanger over time. In addition, the return air introduced into the return air passage 5C has foreign matter removed by the filter 7, and is then returned to the vehicle cabin via the narrow passage 5F, the fan 11, and the supply air passage 5G. Therefore, for example, even if foreign matter such as dust gets mixed into the inside air in the vehicle cabin, the cleanliness of the vehicle cabin can be maintained.

[0025] In summer, when cooling is used, if the driver or passenger of the vehicle switches the mode of the air conditioning system to the circulation mode, the damper 9 operates to close the outside air passage 5B, so that the opening rate of the outside air passage 5B becomes approximately 0%, while the opening rate of the return air passage 5C becomes approximately 100%, as shown in Fig. 5. In the circulation mode in summer, the fan 11 operates, and the return air passes through the filter 7, and then passes through the narrow passage 5F and the fan 11 located downstream of the filter 7, and is introduced into the supply air passage 5G as supply air. In addition, in the circulation mode in summer, 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, so that the temperature inside the vehicle cabin approaches the set temperature.

[0026] In the summer circulation mode, heat exchanger 3 does not exchange heat between the exhaust air and the outside air, but the return air from inside the vehicle cabin is returned to the vehicle cabin after foreign matter has been removed by filter 7, thereby maintaining the cleanliness of the vehicle cabin.

[0027] In winter, when the vehicle driver or passengers set the air conditioning system to the outside air introduction mode, the damper 9 operates to close the return air passage 5C, so that the opening rate of the outside air passage 5B becomes approximately 100%, while the opening rate of the return air passage 5C becomes approximately 0%, as shown in Fig. 6. In the outside air introduction mode in winter, the fan 11 operates, and the outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and then passes through the narrow passage 5F and the fan 11 located downstream of the outside air passage 5B, and is introduced into the supply air passage 5G as supply air. In the outside air introduction mode in summer, 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, so that the temperature inside the vehicle cabin approaches 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, and this pressure difference is used to introduce the exhaust gas into the exhaust passage 5A through 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 the shutter SH of the exhaust port 5D formed in the housing 5, and is 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 such an outside air introduction mode in winter, outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 disposed downstream of the filter 7. As a result, no foreign matter is introduced into the heat exchanger 3 or a significant reduction is achieved, and the progression of clogging of the heat exchanger 3 is suppressed, thereby making it possible to suppress deterioration of the performance of the heat exchanger over time.

[0030] In winter, when the vehicle driver or passengers use heating, when the vehicle air conditioning system is set to the mixed mode, the damper 9 operates to be in the middle position between the outside air introduction state and the return air circulation state, and the opening ratio of the outside air passage 5B and the return air passage 5C is approximately 50%, as shown in FIG. 7. In the mixed mode in winter, the outside air passes through the outside air passage 5B, the filter 7, and the heat exchanger 3 in this order, and the return air from the passenger compartment passes through the return air passage 5C and the filter 7 in this order, as the fan 11 operates. The outside air and the return air then pass through the narrow passage 5F and the fan 11 located downstream of the fan 11, and are introduced into the supply air passage 5G as supply air. In the mixed mode in winter, 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, as in the outside air introduction mode in winter, to bring the temperature inside the passenger compartment 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, and this pressure difference is used to introduce the exhaust gas into the exhaust passage 5A through 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 the shutter SH of the exhaust port 5D formed in the housing 5, and is 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, the outside air passes through the filter 7 to remove foreign matter, and is then introduced into the heat exchanger 3 arranged downstream of the filter 7. Therefore, the foreign matter introduced into the heat exchanger 3 is eliminated or significantly reduced, and the progress of clogging of the heat exchanger 3 is suppressed, thereby making it possible to suppress the deterioration of the performance of the heat exchanger over time. In addition, the return air introduced into the return air passage 5C is returned to the vehicle cabin through the narrow passage 5F, the fan 11, and the supply air passage 5G after the foreign matter is removed by the filter 7, so that the cleanliness of the vehicle cabin can be maintained even if foreign matter such as dust gets mixed into the inside air in the vehicle cabin.

[0033] In winter, when the vehicle driver or passenger switches the air conditioning system to the circulation mode, the damper 9 operates to close the outside air passage 5B, so that the opening rate of the outside air passage 5B becomes approximately 0%, while the opening rate of the return air passage 5C becomes approximately 100%, as shown in Fig. 8. In the circulation mode in winter, the fan 11 operates, and the return air passes through the filter 7, passes through the narrow passage 5F located downstream of the filter 7, and is introduced into the supply air passage 5G as supply air. In addition, in the circulation mode in winter, 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, so that the temperature inside the vehicle cabin approaches the set temperature.

[0034] In the circulation mode in winter, heat exchanger 3 does not exchange heat between the exhaust air and the outside air, but the return air from inside the vehicle cabin is returned to the vehicle cabin after foreign matter has been removed by filter 7, thereby maintaining the cleanliness of the vehicle cabin.

[0035] As described above, in either the summer or winter outdoor air introduction 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 arranged upstream thereof. This prevents the heat exchanger 3 from becoming clogged over time in the HVAC system 1, thereby making it possible to extend the maintenance cycle, for example. Note that since the filter 7 of the HVAC system 1 is normally replaced at a predetermined interval, it is considered to be within the expected range even if foreign matter accumulates therein.

[0036] Here, the control system of the HVAC system 1 will be described. 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 composed of an LSI (Large Scale Integration), an IC (Integrated Circuit), a resistor, a capacitor, etc. (the same applies below).

[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 mix mode or the circulation mode upon startup of the HVAC system 1. When the control unit is made of a microcomputer, an application program for executing the damper control process is stored in advance in the 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 wakefulness 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 advances the process 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 ends the damper control process in 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. Then, after controlling the damper 9, the control unit ends the damper control process in the current control cycle.

[0041] By implementing such a 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, that is, the inside air in the vehicle cabin, reaches or 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, which prevents the driver and passengers from decreasing in alertness. When the mode is switched to the outside air introduction mode, fresh outside air is continuously or intermittently introduced into the vehicle cabin, 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 mix mode or the circulation mode upon startup of the HVAC system 1. When the control unit is made of a microcomputer, an application program for executing the damper control process is stored in advance in the storage device.

[0044] In the first step, the control unit reads the temperature and humidity from the temperature and humidity sensor. 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 obtain 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, in other words, the air inside the vehicle cabin, becomes saturated water vapor.

[0046] In the fourth step, 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 advances the process to the fifth step. 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 in the current control cycle.

[0047] In a 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. Then, after controlling the damper 9, the control unit ends the damper control process in the current control cycle.

[0048] By implementing such a 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 inside air in the vehicle cabin, becomes equal to or higher than the outside air temperature, the amount of outside air introduced into the vehicle cabin is increased. Therefore, the dew point temperature in the vehicle cabin is maintained below the outside air temperature, and for example, it is possible to prevent the windshield from condensing and fogging up. 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 the windshield to condense, 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, combining parts of them appropriately with each other, or replacing parts of them with well-known technology.

[0050] As an 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 arranged over the entire exhaust passage 5A, the outside air passage 5B, and the return air passage 5C, but may be arranged over at least the exhaust passage 5A and the outside air passage 5B. [Explanation of symbols]

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

Claims

1. a heat exchanger that exchanges heat between exhaust air discharged from inside the vehicle interior to outside the vehicle interior and outside air introduced from the outside of the vehicle interior into the vehicle interior; a housing having an exhaust passage that guides the exhaust gas to an exhaust gas 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 within 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 the outside of the vehicle cabin; a filter disposed across at least the exhaust passage and the outside air passage among the exhaust passage, the outside air passage, and the return air passage, on the upstream side of the exhaust inlet and the outside air inlet of the heat exchanger; a damper disposed upstream of the filter, the damper changing an opening ratio of the outside air passage and the return air passage to adjust an amount of outside air introduced into the vehicle interior; An air conditioning device having the above structure.

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

3. A concentration sensor for detecting a carbon dioxide concentration of the return air flowing through the return air passage; 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; The air conditioner of claim 1 , further comprising:

4. A temperature and humidity sensor for detecting the temperature and humidity of the return air flowing through the return air passage; An outside air temperature sensor for detecting an outside air temperature; 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 an outside air temperature detected by the outside air temperature sensor; The air conditioner of claim 1 , further comprising:

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

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