JP3563479B2 - Electric vehicle air conditioner - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an air conditioner for an electric vehicle, and more particularly to an air conditioner for an electric vehicle in which fogging of a windshield is prioritized over defrosting of an outside heat exchanger.
[0002]
[Prior art]
Conventionally, in an air conditioner for an electric vehicle, by circulating a heat exchange medium in a heat pump cycle, the inside air or outside air is heated or cooled by a heat exchanger inside the vehicle, and a predetermined airflow mode is selected, so that a predetermined air blowing mode is selected. Warm or cool air is supplied from the position. In this case, the outside heat exchanger absorbs heat when radiating heat in the inside heat exchanger, and radiates heat when absorbing heat. Therefore, when the outside air temperature is extremely low during heating, if heat is absorbed by the heat exchanger on the outside of the vehicle, frost may form on the surface of the heat exchanger. Therefore, in order to prevent the heat exchange efficiency of the vehicle-side heat exchanger from being lowered or damaged, the frost is removed by changing the circulation direction of the heat exchange medium and heating the vehicle-side heat exchanger itself. The defrost operation is performed.
[0003]
[Problems to be solved by the invention]
However, in the conventional air conditioner for electric vehicles, when frost is formed on the outside heat exchanger during heating, the air conditioner is switched to the cooling mode, so that the air passing through the inside heat exchanger is cooled. As a result, cold air was supplied to the interior of the vehicle, causing discomfort to the occupants. In addition, when frost or fogging is occurring on the outer surface of the windshield, even when the DEF mode in which air is directly blown to the windshield is selected, the defrosting operation is performed by the heat exchanger on the outside of the vehicle. For example, there is a problem that the air passing through the heat exchanger inside the vehicle is cooled, and the frost and fogging cannot be removed.
[0004]
In view of the above problems, the present invention minimizes the discomfort experienced by the occupant even when frost is formed on the vehicle exterior heat exchanger, and reduces frost and fogging on the windshield. It is an object of the present invention to provide an electric vehicle air conditioner that can be removed to secure visibility.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a compressor, an inboard heat exchanger, an outboard heat exchanger, a heat pump cycle having an expansion valve, by switching a circulation direction of a heat exchange medium to a heating mode or a cooling mode, After heating or cooling the air passing through the heat exchanger inside the vehicle, while selecting a blowing mode to supply warm air or cold air from a predetermined air outlet inside the vehicle, By detecting frost formation, in an electric vehicle air conditioner that performs a defrosting operation by changing the circulation direction of the heat exchange medium,
If the DEF mode in which the air is blown directly to the inner surface of the windshield is selected as the blowing mode, the circulating direction of the heat exchange medium is kept in the heating mode, and the frost formation in the heat exchanger outside the vehicle is detected. Even if there is, an air conditioner control means for delaying the detection of the frost formation for a predetermined time is provided.
[0006]
The air conditioner control means may delay the start of the defrosting operation until the degree of frost formation exceeds a predetermined threshold. In this case, the degree of frost formation may be estimated from the surface temperature of the vehicle-side heat exchanger, or may be estimated from the pressure of the heat exchange medium.
[0008]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0009]
In the electric vehicle air conditioner shown in FIG. 1, the cycle in which the heat exchange medium circulates can be switched between the heating cycle and the cooling cycle by the four-way valve 1. During these cycles, a compressor 2, an inboard heat exchanger 3, a throttle valve 4, an outboard heat exchanger 5, and an accumulator 6 are provided in addition to the four-way valve 1.
[0010]
The four-way valve 1 has a structure in which a rotating body having a pair of communication passages is accommodated in a valve body, and is switched as indicated by a solid line in a heating mode and a dotted line in a cooling mode based on a control signal from a cycle switching device 7. It switches as shown by.
[0011]
The compressor 2 is driven by a built-in motor (not shown) by a frequency adjusting device 8 at a predetermined frequency, and discharges the heat exchange medium sucked into the inside at a predetermined flow rate in a high temperature / high pressure state according to the driving frequency. I do.
[0012]
The inside heat exchanger 3 and the outside heat exchanger 5 have a structure in which flat tubes and corrugated fins are laminated and integrated. When the heat exchange medium flows meandering through the flat tubes, the fins are interposed. Heat exchange with the passing air.
[0013]
The in-vehicle heat exchanger 3 is disposed in the unit 9 at the front of the vehicle, and radiates heat in the heating mode to warm the passing air, and cools it in the cooling mode. An in-vehicle heat exchange temperature sensor 10 is provided near the downstream side of the in-vehicle heat exchanger 3 to detect the surface temperature.
[0014]
On the other hand, the vehicle-side heat exchanger 5 is attached to a front portion of the vehicle, and heat exchange is performed between a heat exchange medium flowing inside the vehicle and the traveling wind. An outside heat exchange temperature sensor 11 is provided near the downstream of the outside heat exchanger 5 so that the surface temperature of the outside heat exchanger 5 is detected.
[0015]
The accumulator 6 stores a heat exchange medium, separates gas and liquid, and supplies only gas to the compressor 2.
[0016]
Inside the unit 9, a blower 12 and an electric heater 13 are arranged outside the vehicle-side heat exchanger 3.
[0017]
The blower 12 is located upstream of the heat exchanger 3 on the inside of the vehicle, and is based on a control signal from an air volume controller 14 in the case of manual control, and based on a control signal from an air volume controller 15 in the case of automatic control. Inside air or outside air is sucked into the unit 9 by the rotating blower motor 12a, and is blown to the inside of the vehicle.
[0018]
The electric heater 13 is provided downstream of the heat exchanger 3. Based on a control signal from the power supply control device 16, the electric heater 13 is insufficiently heated only with the in-vehicle heat exchanger 3 to obtain a desired blast temperature, or after being dehumidified and cooled by the in-vehicle heat exchanger 3. It is used when performing dehumidifying and heating.
[0019]
The most downstream portion of the unit 9 is a blower unit 9a, which can open and close the air outlets 18a and 18b by a damper 17 or the like so that air can be blown into the vehicle from a desired air outlet inside the vehicle. The opening and closing of the damper 17 and the like is performed based on a control signal from the air outlet setting device 19. For example, if the DEF mode is selected by the blower opening setting device 19, it is possible to blow air directly to the inner surface of the windshield by opening the blower outlet 18a with the damper 17.
[0020]
Outside air temperature sensor 10 and outside air temperature sensor 11, inside air sensor 20 (a sensor provided at the foot of the front part inside the vehicle and detecting inside air temperature), solar radiation sensor 21 (dash in the front part inside the vehicle) Detection signals from various sensors, such as a sensor provided on a board or the like and detecting the amount of solar radiation, are input to the air conditioner control device 22.
[0021]
The air conditioner control device 22 outputs control signals to the cycle switching device 7, the frequency adjustment device 8, the air volume control device 15, the energization control device 16, and the air outlet setting device 19 based on these input signals, and according to the flowchart of FIG. Perform air conditioning control.
[0022]
That is, first, in step S1, detection signals (in-vehicle external conditions) from the respective sensors are read, and in step S2, a target air-blowing temperature and a target air-blowing amount are calculated based on the vehicle internal and external conditions by a conventionally known method. I do.
[0023]
In step S3, the drive speed of the blower 12, the drive frequency of the compressor 2, and the amount of electricity supplied to the electric heater 13 are drive-controlled based on the calculated target air temperature and target air volume, respectively, and the air conditioning inside the vehicle is performed. Is started (the inside temperature of the vehicle is adjusted to the set temperature by performing air conditioning in the vehicle at the target air temperature and the target air volume).
[0024]
Next, in step S4, it is determined whether the in-vehicle air conditioning is performed in the heating mode. The determination as to whether the mode is the heating mode is made based on a control signal from the cycle switching device 7 for switching the four-way valve 1.
[0025]
If the heating mode has not been selected, steps S1 to S3 are repeated. On the other hand, when the heating mode is selected, it is determined in step S5 whether frost has formed on the vehicle-side heat exchanger 5 or not. In this case, the frost formation in the outside heat exchanger 5 is estimated based on whether or not the temperature detected by the outside heat exchange temperature sensor 11 is equal to or lower than a predetermined threshold. That is, since the vehicle exterior heat exchange temperature sensor 11 detects the surface temperature of the vehicle exterior heat exchanger 5, if the detected temperature is equal to or lower than the threshold value (for example, -13 ° C.), frost formation occurs. It is because it can be guessed that there is. The frost formation may be inferred from the pressure of the heat exchange medium flowing inside the vehicle-side heat exchanger 5, and the pressure of the heat exchange medium is determined by a pressure sensor (not shown) during the heat pump cycle. ) May be detected.
[0026]
If it is estimated that there is no frost, the steps S1 to S4 are repeated, and the blower 12 and the like are drive-controlled based on the target air temperature and the target air volume calculated from the various conditions inside and outside the vehicle, and the air conditioning in the vehicle is performed as usual. continue.
[0027]
On the other hand, when it is estimated that there is frost, it is determined in step S6 whether the DEF mode is selected as the blowing mode. This determination is made based on a selection signal from the air outlet setting device 19.
[0028]
When the DEF mode is selected, the process returns to step S1 and continues heating by the in-vehicle heat exchanger 3, as in steps S4 and S5. That is, during heating, the DEF mode is selected when the windshield is frosted or fogged. Even if frost is formed, the heat is absorbed by the heat exchanger 5 on the outside and the heating by the heat exchanger 3 on the inside is continued. In this case, the heat exchange in the vehicle-side heat exchanger 5 cannot be performed sufficiently due to frost, so that the heating capacity in the vehicle-side heat exchanger 3 is slightly deteriorated, but warm wind can be supplied to the windshield. As a result, it is possible to remove frost or fogging of the windshield. Further, since the air passing through the inside heat exchanger 3 is not cooled by the start of the defrosting operation, no cool air is supplied to the inside of the vehicle, and the occupant does not feel uncomfortable.
[0029]
On the other hand, if the DEF mode has not been selected, the defrosting operation is started in step S7. In this case, it is preferable to suppress or stop the amount of air blown by the blower 12. Thus, the supply of the air cooled by the vehicle interior heat exchanger 3 to the vehicle interior can be suppressed or prevented, and the discomfort experienced by the occupant can be minimized.
[0030]
If the defrosting operation is started in this way, it is determined in step S8 whether or not the defrosting has been completed. If the defrosting has not been completed, the defrosting operation (step S7) is continued, and the defrosting operation is continued. Is completed, the process returns to step S1 to repeat the above operation. In this case, the completion of the defrosting is determined based on whether or not the temperature detected by the vehicle outside heat exchange temperature sensor 11 exceeds a predetermined threshold value, similarly to the determination of the frost formation. However, the threshold for judging the completion of the defrosting is set slightly higher than the threshold for judging the frosting (for example, −5 ° C.). Accordingly, it is possible to prevent a problem that the determination of whether frost is formed or the defrost is completed is frequently switched due to a change in the temperature detected by the vehicle outside heat exchange temperature sensor 11. If the DEF mode is selected in step S6 during the defrosting operation, the process returns to step S1 to start the heating operation even if the defrosting operation is being performed.
[0031]
In the above-described embodiment, when the heating mode is selected, the defrosting operation is forcibly started in step S6 if the DEF mode is selected even if frost is formed on the vehicle-side heat exchanger 5. Although not performed, the detection of frost formation may be delayed for a predetermined time.
[0032]
In this case, the time for delaying the frost detection is set to a time at which it is estimated that the fogging generated on the windshield can be removed to a certain level, or it is estimated that the outside heat exchanger 5 is damaged by frost. For example, it can be set to a predetermined time shorter than the required time. Further, this time does not necessarily have to be a constant value, and may be freely changed in accordance with various conditions inside and outside the vehicle, for example, when the outside air temperature is relatively high, the time is set again longer.
[0033]
In addition to the time management as described above, it is assumed that the temperature detected by the vehicle exterior heat exchange temperature sensor 11 and the pressure detected by the pressure sensor detect the temperature or pressure at which frost formation is expected to be detected. Also, the defrosting operation may not be started until the temperature (for example, −18 ° C.) or the pressure (for example, 0.15 MPa), which is expected to be detected when the degree of frosting has progressed to some extent, or less. Good.
[0034]
According to this, it is possible to cause the inside-side heat exchanger 3 to perform heating to a limit state in which a problem due to frost formation in the outside-side heat exchanger 5 (such as obstruction of air blowing or a decrease in heat absorption capacity) does not become a problem. It becomes possible.
[0035]
【The invention's effect】
As is apparent from the above description, according to the present invention, even if frost is formed on the vehicle-side heat exchanger, if the DEF mode is selected, the vehicle-side heat exchanger is forced to operate. , The heat can be heated by the heat exchanger inside the vehicle, so that it is possible to supply warm wind to the windshield, and it is possible to effectively remove the fogging.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an electric vehicle air conditioner according to an embodiment.
FIG. 2 is a flowchart illustrating air conditioning control according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Four-way valve 2 Compressor 5 Outside heat exchanger 7 Cycle switching device 17 Dampers 18a, 18b Air outlet 22 Air conditioner control device

Claims (2)

A heat pump cycle having a compressor, an inboard heat exchanger, an outboard heat exchanger, and an expansion valve switches a circulation direction of a heat exchange medium to a heating mode or a cooling mode, and heats air passing through the inboard heat exchanger. Or, after cooling, the air supply mode is selected to supply warm air or cold air from a predetermined air outlet inside the vehicle, while detecting frost on the heat exchanger outside the vehicle in the heating mode, the heat exchange medium In an air conditioner for an electric vehicle that performs a defrosting operation by changing a circulation direction of
If the DEF mode in which the air is blown directly to the inner surface of the windshield is selected as the blowing mode, the circulating direction of the heat exchange medium is kept in the heating mode, and the frost formation in the heat exchanger outside the vehicle is detected. An air conditioner for an electric vehicle, further comprising an air conditioner control means for delaying detection of the frost even for a predetermined time. 2. The air conditioner for an electric vehicle according to claim 1, wherein the air conditioner control means delays the start of the defrosting operation until the degree of frost formation exceeds a predetermined threshold.

Images