JP2013203196A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner for a vehicle capable of avoiding such an event that effective heat exchange cannot be performed over a long period of time, by preventing dew or frost from accumulating in a heat exchanger.SOLUTION: An air conditioner for a vehicle includes a heat exchanger 11 which comprises a first flow passage and a second flow passage and exchanges heat between the air flowing through the first flow passage and the air flowing through the second flow passage, an inside air introduction flow passage 15 for introducing the inside air sent out from the inside of a cabin to the first flow passage, an evaporator 13 for cooling air, an evaporator discharge air introduction flow passage 19 for introducing evaporator discharge air into the inside air introduction flow passage 15, an evaporator discharge air introduction door 20 which is disposed at an inlet of the evaporator discharge air introduction flow passage 19 and can change an evaporator discharge air introduction amount according to the degree of the opening thereof, and a control unit 26 for controlling the opening of the evaporator discharge air introduction door 20 based on the difference between the outside air temperature on the outside of the vehicle and a predetermined temperature.

Description

  The present invention relates to a vehicle air conditioner provided with a heat exchanger.

  In a vehicle air conditioner, a heat exchanger such as a sensible heat exchanger or a total heat exchanger may be used when the vehicle interior is ventilated during heating. These heat exchangers flow warm air (referred to as inside air) sent from the interior of the vehicle and cold air (referred to as outside air) taken from the outside of the vehicle through two adjacent flow paths, and intake air from the exhaust. Move heat to. By recovering this heat, it is possible to save energy in the heating operation in the air conditioner.

  A vehicle air conditioner including such a heat exchanger is disclosed in, for example, Patent Document 1. In Patent Document 1, by using a sensible heat exchanger, heat is exchanged between the inside air discharged from the inside of the vehicle and the outside air introduced from the outside of the vehicle, thereby recovering the heat of the inside air to the outside air and improving the air conditioning efficiency.

JP 2002-200910 A

  In the heat exchanger, when the outside air temperature is very low, dew or frost may be generated in the flow path of the inside air. When dew or frost is generated in the heat exchanger, there is a problem that the heat exchange efficiency of the heat exchanger is greatly reduced until these are removed. In addition, once dew or frost accumulates in the heat exchanger, it takes a long time to remove these, and there is a problem that effective heat exchange cannot be performed during that time.

  An object of the present invention is to provide a vehicle air conditioner that can prevent dew or frost from accumulating in a heat exchanger, thereby avoiding a situation in which effective heat exchange cannot be performed over a long period of time.

  A vehicle air conditioner according to an aspect of the present invention includes a first flow path and a second flow path, and exchanges heat between air flowing through the first flow path and air flowing through the second flow path. A heat exchanger that conducts air, a first air passage that guides the inside air sent from the passenger compartment to the first flow path, a cooling heat exchanger that cools air, and an exhaust gas from the cooling heat exchanger that is exhausted from the first air passage. A second air passage that leads to the air passage, a flow rate changing section that can change an amount of the exhaust gas introduced into the first air passage according to an opening, and a temperature difference between an outside air temperature outside the vehicle and a predetermined temperature, And a control unit that controls the opening degree of the flow rate changing unit.

  According to the present invention, the flow rate changing unit controls the amount of exhaust of the cooling heat exchanger introduced into the first air passage leading to the first flow path of the heat exchanger, so that dew or frost is generated in the heat exchanger. It is possible to prevent a large amount of accumulation. Accordingly, it is possible to avoid a situation in which effective heat exchange cannot be performed over a long period due to generation of dew or frost generated in the heat exchanger.

The block diagram which shows the principal part of the vehicle air conditioner which concerns on Embodiment 1 of this invention. The perspective view which shows the structure of a sensible heat exchanger The flowchart which shows the procedure of the evaporator exhaust introduction door control processing performed by the control part of Embodiment 1. The principle figure which shows the principal part of the vehicle air conditioner which concerns on Embodiment 2 of this invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram showing a main part of a vehicle air conditioner according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the vehicle air conditioner of Embodiment 1 includes a sensible heat exchanger 11 as a heat exchanger, a fan 12, an evaporator 13, a heater 14, an inside air introduction passage 15, an inside air discharge passage 16, An outside air introduction channel 17, a blower channel 18, an evaporator exhaust introduction channel 19, an evaporator exhaust introduction door 20, an intake door 21, a hot air switching door 22, temperature sensors 23 and 24, a humidity sensor 25, and a control unit 26 I have.

  The inside air introduction flow path 15 is connected to the inside air introduction side of the sensible heat exchanger 11 while the introduction port leads to the vehicle interior.

  The outside air introduction flow path 17 has an introduction port facing an inflow portion of air outside the vehicle. As for the ventilation flow path 18, the delivery port is connecting with the vehicle interior.

  The inside air discharge channel 16 faces a location where the outlet can discharge air to the outside of the vehicle. In addition, the air sent out from the inside air discharge passage 16 can be used by returning a part to the air conditioner without directly discharging it out of the vehicle.

  The evaporator exhaust introduction flow path 19 is connected to the inside air introduction flow path 15 on the delivery side, while the introduction port leads to the air flow path 18 near the discharge port of the evaporator 13.

  FIG. 2 is a perspective view showing the sensible heat exchanger 11.

  As shown in FIG. 2, the sensible heat exchanger 11 is a stationary heat exchanger with a fixed flow path. The sensible heat exchanger 11 has two adjacent channels A and B, flows high temperature air through one channel A (corresponding to the first channel), and the other channel B (second Flow air at a low temperature to the flow path). Thereby, in the sensible heat exchanger 11, the heat of the air of the flow path A can be moved to the air of the flow path B without mixing the air of the flow path A and the flow path B. A large number of fine channels are provided in the channels A and B of each system, and the contact areas of the channels A and B of the two systems are increased by arranging the fine channels of each system so as to intersect each other. .

  In the sensible heat exchanger 11, an inside air introduction passage 15 and an inside air discharge passage 16 are connected to one end and the other end of the passage A, respectively. Further, in the sensible heat exchanger 11, the outside air introduction flow path 17 and the suction port of the fan 12 are connected to one end and the other end of the flow path B, respectively. The blower opening of the fan 12 is connected to the blower passage 18.

  By connecting the sensible heat exchanger 11 and each flow path as described above, the inside air discharged from the vehicle interior passes through the flow path A of the sensible heat exchanger 11 and passes through the flow path B of the sensible heat exchanger 11 from the outside of the vehicle. Inhaled outside air passes. Then, in the sensible heat exchanger 11, heat is transferred from the exhausted inside air to the outside air that is sucked, and heat recovery of the exhaust is performed during ventilation.

  The fan 12 sucks outside air from the outside air introduction flow path 17 and generates pressure to send the sucked air to the vehicle interior via the air blowing flow path 18 (in FIG. 1, the flow of air is indicated by a band-shaped arrow). ).

  The evaporator 13 (corresponding to a heat exchanger for cooling) is an apparatus that cools air by flowing a refrigerant cooled by using a heat pump and exchanging heat between the refrigerant and the passing air. It is provided in the middle of the air flow path 18. When cooling is unnecessary, such as during heating, the operation of the heat pump is stopped, so that the evaporator 13 may pass air as it is without cooling the air. The evaporator 13 operates and cools the air.

  The heater 14 is a device that warms the passing air. The heater 14 can be composed of a condenser for flowing a refrigerant heated using a heat pump, or, if there is another heat source, a heat exchanger or the like that is brought to a high temperature by introducing heat from this heat source.

  The evaporator exhaust introduction door 20 is not particularly limited, but is in the form of a rotating door. The evaporator exhaust introduction door 20 is disposed at the introduction port of the evaporator exhaust introduction passage 19 and is opened and closed by electrical control by the actuator 20a.

  The hot air switching door 22 is a door for switching whether or not to flow air to the heater 14.

  The intake door 21 is a door that is provided in the outside air introduction channel 17 and adjusts the amount of outside air that is sucked into the channel B of the sensible heat exchanger 11.

  The temperature sensor 23 is a sensor that detects the temperature of outside air outside the vehicle. The sensor signal of the temperature sensor 23 is output to the control unit 26.

  The temperature sensor 24 is disposed at the inlet of the flow path A of the sensible heat exchanger 11 and detects the temperature of the air introduced into the flow path A. The humidity sensor 25 is a sensor that is disposed at the inlet of the flow path A of the sensible heat exchanger 11 and detects humidity. These temperature sensor 24 and humidity sensor 25 output sensor signals to the control unit 26. The dew point temperature can be calculated from the temperature and humidity at the inlet of the sensible heat exchanger 11.

  The control unit 26 includes an input / output circuit that inputs sensor signals from the temperature sensors 23 and 24 and the humidity sensor 25 and outputs an opening / closing control signal to an actuator 20 a that opens and closes the evaporator exhaust introduction door 20. In addition, the control unit 26 includes an arithmetic device that executes a predetermined control process.

[Control action]
Next, the control operation of the vehicle air conditioner in Embodiment 1 will be described.

[Evaporator exhaust door control]
FIG. 3 shows a flowchart of the control process of the evaporator exhaust introduction door 20 in the first embodiment, which is executed by the control unit 26.

  This control process is repeatedly executed at a predetermined cycle (for example, a cycle of 5 minutes) while the electric system of the vehicle is powered on.

  In addition, when the vehicle air conditioner is configured to be able to switch between the operation and stop of the ventilation operation (drive of the fan 12), the control process of FIG. 3 is repeatedly executed only during the operation of the ventilation operation. You may comprise. Further, in the case where the presence / absence of outside air introduction is switched by opening / closing the intake door 21, the control process of FIG. 3 may be repeatedly executed only during a period in which outside air introduction is performed. .

  When this control process is started, the control unit 26 first inputs sensor signals from the temperature sensor 24 and the humidity sensor 25, and the sensible heat exchanger inlet temperature (hereinafter referred to as "sensible heat inlet temperature"). Ti and sensible heat exchanger inlet humidity (hereinafter referred to as “sensible heat inlet humidity”) Ra are acquired. Then, the control unit 26 calculates the dew point temperature Td from the sensible heat inlet temperature Ti and the sensible heat inlet humidity Ra (step S11). At the same time, the control unit 26 inputs the sensor signal of the temperature sensor 23 and also acquires the outside air temperature To.

  Subsequently, the control unit 26 compares the outside air temperature To with the dew point temperature Td (steps S12 to S14), and adjusts the opening degree Va of the evaporator exhaust introduction door 20 based on the comparison result (steps S15 to S18). .

  Next, the control unit 26 determines that the value obtained by subtracting the dew point temperature Td from the outside air temperature To (temperature difference between the outside air temperature To and the dew point temperature Td) is higher than the arbitrary temperature T1 (“Yes” in step S12). ), The evaporator exhaust introduction door 20 is closed by a relatively large fixed amount (Vy) (step S18).

  In addition, if the control unit 26 determines that the value obtained by subtracting the dew point temperature Td from the outside air temperature To is between 0 and an arbitrary temperature T1 (“Yes” in step S13), the control unit 26 moves the evaporator exhaust introduction door 20 relatively. Only a small fixed amount (Vx) is closed (step S17).

  If the control unit 26 determines that the value obtained by subtracting the dew point temperature Td from the outside air temperature To is between -T2 (T2 is an arbitrary temperature) and 0 ("Yes" in step S14), the evaporator exhaust introduction is performed. The opening degree Va of the door 20 is not changed (step S16).

  If the control unit 26 determines that the value obtained by subtracting the dew point temperature Td from the outside air temperature To is −T2 or less (“No” in step S14), the evaporator exhaust introduction door 20 is opened by a certain amount (Vz). .

  By adjusting the opening degree Va of the evaporator exhaust introduction door 20, the evaporator exhaust introduction door 20 is gradually opened when the sensible heat exchanger 11 is likely to generate dew or frost, and the evaporator 13 dehumidifies and cools it. The amount of introduced air (evaporator exhaust) is increased. For example, when the outside air temperature To is lower than the dew point temperature Td, the evaporator exhaust introduction door 20 is opened, and when the outside air temperature To is slightly lower than the dew point temperature Td, the evaporator exhaust introduction door 20 is opened slowly.

  That is, when the outside air temperature To is lower than the predetermined temperature (dew point temperature Td) (“No” in step S13), the evaporator exhaust introduction door 20 is moved in accordance with the temperature difference between the outside air temperature To and the dew point temperature Td. Open and control to increase the amount of exhaust.

  Here, if the evaporator exhaust introduction door 20 increases the introduction amount of the exhaust of the evaporator 13 (evaporator exhaust) too much, the temperature of the inside air introduced from the inside of the vehicle is lowered, and the efficiency of the sensible heat exchanger 11 is also lowered. It is desirable to moderate the amount of evaporator exhaust introduced.

  If the opening degree of the evaporator exhaust introduction door 20 is adjusted in steps S15 to S18, the control unit 26 ends this control process. Then, this control process is started again at the next cycle.

  By such opening / closing control of the evaporator exhaust introduction door 20, when the relative temperature of the outside air temperature To based on the dew point temperature Td is high, the introduction amount of the evaporator exhaust is reduced. On the other hand, when the relative temperature of the outside air temperature To is low, the amount of evaporator exhaust introduced is increased. Therefore, the inside air cooled by the evaporator 13 is mixed with the inside air introduced from the inside of the vehicle, so that the absolute humidity and dew point temperature of the air passing through the sensible heat exchanger 11 are reduced and the sensible heat exchanger 11 is exposed to dew or frost. Is prevented from accumulating.

  As described above, according to the vehicle air conditioner of the first embodiment, the condition where dew is likely to be generated in the sensible heat exchanger 11 from the relationship between the outside air temperature and the dew point temperature at the inlet of the sensible heat exchanger 11. Sometimes the evaporator exhaust introduction door 20 is opened and closed so that the amount of air cooled by the evaporator 13 increases. Therefore, the absolute humidity and temperature of the air passing through the sensible heat exchanger 11 can be kept moderate, and a large amount of dew or frost can be prevented from accumulating in the sensible heat exchanger 11. Therefore, the situation where the sensible heat exchanger 11 cannot be effectively used over a long period due to dew or frost can be avoided.

(Embodiment 2)
FIG. 4 is a principle diagram showing a main part of the vehicle air conditioner in the second embodiment.

  The vehicle air conditioner according to the second embodiment is different from the vehicle air conditioner according to the first embodiment in that a fan 28 and an evaporator 13 are provided between the outside air introduction passage 27 and the outside air discharge passage 29. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The outside air introduction passage 27 has an introduction port facing an inflow portion of air outside the vehicle, and a delivery side connected to the suction port of the fan 28. The blower opening of the fan 28 is connected to the evaporator 13.

  The outside air discharge channel 29 faces a location where the outlet can discharge air to the outside of the vehicle. In addition, an evaporator exhaust introduction passage 19 and an evaporator exhaust introduction door 20 are installed in the vicinity of the evaporator outlet.

  The vehicle air conditioner according to the second embodiment prevents a large amount of dew or frost from accumulating in the sensible heat exchanger 11 by the same operation as that of the first embodiment, and the sensible heat exchanger 11 due to the dew or frost. It is possible to avoid such a situation that cannot be used effectively over a long period of time.

  The embodiments of the present invention have been described above.

  In the first and second embodiments, a value obtained by subtracting the dew point temperature Td from the outside air temperature To is used. However, instead of the dew point temperature Td, the sensible heat exchanger inlet temperature (sensible heat inlet temperature) Ti) can be used. In addition, the freezing temperature of water can be used instead of the dew point temperature Td. The freezing temperature of water changes with atmospheric pressure.

  The sensible heat inlet temperature Ti or the freezing temperature of water can be used in place of the dew point temperature Td because these temperatures can serve as reference temperatures for predicting the occurrence of dew or frost. Because there is.

  In the above-described embodiment, the evaporator exhaust introduction door 20 has been described as an example in which the flow rate is changed by opening and closing the door. However, the evaporator exhaust introduction door 20 is employed in various valves, for example. The known forms can be applied.

  Moreover, although the said embodiment demonstrated as an example the structure which applied the sensible heat exchanger as a heat exchanger, the structure which applied the total heat exchanger is also employable.

  In addition, the details shown in the embodiment, such as the conditions for opening and closing the evaporator exhaust introduction door 20 and the amount of opening and closing, can be changed without departing from the spirit of the invention.

  The present invention can be applied to a ventilator or an air conditioner mounted on a vehicle.

DESCRIPTION OF SYMBOLS 11 Sensible heat exchanger 12, 28 Fan 13 Evaporator 14 Heater 15 Inside air introduction flow path 16 Inside air discharge flow path 17, 27 Outside air introduction flow path 18 Blower flow path 19 Evaporator exhaust introduction flow path 20 Evaporator exhaust introduction door 21 Intake door 22 Temperature Wind switching door 23, 24 Temperature sensor 25 Humidity sensor 26 Control unit 29 Outside air discharge flow path

Claims (6)

A heat exchanger having a first channel and a second channel and exchanging heat between the air flowing through the first channel and the air flowing through the second channel;
A first air passage for guiding the inside air sent from the passenger compartment to the first passage;
A cooling heat exchanger for cooling the air;
A second air passage for guiding the exhaust of the heat exchanger for cooling to the first air passage;
A flow rate changing unit capable of changing an amount of the exhaust gas introduced into the first air passage according to an opening;
A control unit for controlling the opening of the flow rate changing unit based on a temperature difference between an outside air temperature outside the vehicle and a predetermined temperature;
A vehicle air conditioner comprising: When the outside air temperature is lower than the predetermined temperature, the control unit opens the flow rate changing unit in a direction to increase the amount of the exhaust gas as the temperature difference between the outside air temperature and the predetermined temperature increases. To control the
The vehicle air conditioner according to claim 1. The predetermined temperature is a dew point temperature at the inlet of the heat exchanger.
The vehicle air conditioner according to claim 1. The predetermined temperature is a temperature at an inlet of the heat exchanger.
The vehicle air conditioner according to claim 1. The predetermined temperature is a freezing temperature of water.
The vehicle air conditioner according to claim 1. The heat exchanger is a sensible heat exchanger,
The vehicle air conditioner according to claim 1 or 2.

Images