JP3737137B2 - Air conditioner for electric vehicles - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a defrosting means for an air conditioner for an electric vehicle, and more particularly to a defrosting means provided with a frosting detection sensor capable of accurately detecting frosting in an outside heat exchanger.
[0002]
[Prior art]
In electric vehicle air conditioners, the four-way valve is switched to the heating cycle, and the compressor is driven using battery power to circulate the heat exchange medium in the order of the vehicle interior heat exchanger and vehicle exterior heat exchanger in order of heating. To do. In this heating operation, heat is absorbed from the ambient atmosphere in the outside heat exchanger, so if the outside air temperature is very low, frost forms on the surface of the outside heat exchanger and the heat exchange efficiency deteriorates. is there.
[0003]
For this reason, conventionally, a frost detection sensor is provided in the vehicle exterior heat exchanger, and the presence or absence of frost formation in the vehicle exterior heat exchanger is estimated based on the temperature detected by the frost detection sensor. If it is judged that it is, it defrosts by switching a four-way valve and setting it as a cooling cycle.
[0004]
[Problems to be solved by the invention]
However, there is a problem that a large difference occurs in the detected temperature due to a difference in the attachment position of the frost detection sensor, and the defrosting operation is started even though the outside heat exchanger is not frosted due to a malfunction.
For example, if the frost detection sensor is installed at a position where the air blows from the fan or the traveling wind hits it, the frost is detected even though the temperature of the outside heat exchanger becomes very low and frost is generated. Depending on the air temperature, a temperature higher than the actual surface temperature of the outside heat exchanger may be detected.
[0005]
Further, immediately after the heating operation is started, the temperature of the heat exchange medium greatly fluctuates. In particular, when the frost detection sensor is provided in the vicinity of the inlet of the heat exchange medium of the outside heat exchanger, the fluctuation range is remarkable. Therefore, as a result of the temperature being lowered to a temperature (for example, −13 ° C.) which is a reference for frost determination, there is a risk of malfunction.
In view of the above problems, an object of the present invention is to provide a defrosting means for an air conditioner for an electric vehicle capable of accurately detecting a frosting state and performing a defrosting operation.
[0006]
[Means for Solving the Problems]
The present invention, in order to achieve the object, the interior side heat exchanger heat exchange medium was elevated temperature and pressure in the compressor, when performing a heating operation by circulating in the order of the exterior heat exchanger, the vehicle outer side If frost formation of the outside heat exchanger is detected based on the temperature detected from the frost detection sensor attached to the heat exchanger, the heat exchange medium is reversely circulated by switching the four-way valve to switch the outside of the vehicle. In the air conditioner for an electric vehicle that is defrosted from the heat exchanger, the frost detection sensor is a position where the air blown from the fan provided in the vicinity of the vehicle outside heat exchanger and the traveling wind cannot be blown, Immediately after the start of the heating operation, the heat exchange medium is provided at a position other than the range where the initial temperature disturbance that occurs when the heat exchange medium flows into the outside heat exchanger, and the detected temperature from the frost detection sensor is the outside heat exchange. Frost on the vessel Even if the set value or less and which is determined to have none, it is provided with a defrosting control means to continue the heating operation if beyond a certain range the variation degree of the detected temperature.
[0007]
In addition, the frost detection sensor may be provided at a position other than a range where an initial temperature disturbance occurs when the heat exchange medium flows into the vehicle exterior heat exchanger.
Furthermore, you may make it provide the defrost control means which performs frost determination after predetermined time passes since heating operation start.
[0008]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
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, the compressor 2, the vehicle interior heat exchanger 3, the vehicle exterior heat exchanger 4 and the accumulator 5 are disposed outside the four-way valve 1.
[0009]
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. Based on a control signal from a control device (not shown), the four-way valve 1 is switched as indicated by a solid line during heating, and is indicated by a dotted line during cooling. Switch as shown.
The compressor 2 is driven by the electric power supplied from the inverter 2a, and discharges the heat exchange medium sucked inside as a high temperature / high pressure state.
[0010]
The vehicle interior heat exchanger 3 and vehicle exterior heat exchanger 4 have substantially the same configuration, and the vehicle exterior heat exchanger 4 includes a plurality of flat tubes 7 between a pair of headers 6a and 6b as shown in FIG. It is formed by arranging fins 8 arranged in parallel at predetermined intervals and alternately bent between the flat tubes 7. One header 6a has a heat exchange medium inlet 9a at its lower end and an upper end. Are respectively provided with outlets 9b. The vehicle exterior heat exchanger 4 is attached to the front portion of the vehicle, and ambient air is forcibly blown from the fans 10 provided at two locations in the vicinity thereof. When the heat exchange medium flows upward while meandering from the flat tube 7 on the lower side, heat is absorbed from the air or running wind blown by the fan 10 through the fins 8 and the heat exchange medium absorbs heat. It is like that.
[0011]
On the other hand, the vehicle interior heat exchanger 3 is disposed in a blower unit 11 provided on the vehicle interior side, and heats the inside air or the outside air sucked into the blower unit 11 by rotational driving of the blower 12.
The accumulator 5 plays a role of supplying the heat exchange medium absorbed by the vehicle exterior heat exchanger 4 to the compressor 2 in a pressurized state.
[0012]
Meanwhile, a frost detection sensor 13 such as a thermistor is attached to the outside heat exchanger 4 at a position where the air blown from the fan 10 does not directly hit as shown in FIG.
The frost detection sensor 13 can be attached using attachment members 14 and 15 as shown in FIGS.
[0013]
The attachment member 14 shown in FIGS. 3 and 4 is inserted between the fins 8 of the heat exchanger 4 on the outside of the vehicle, and is provided with a locking portion 17 that is prevented from dropping by a locking claw 16 formed at the tip, and the frost detection. It is comprised from the heat insulation part 18 which coat | covers except the part which opposes the vehicle exterior heat exchanger 4 of the sensor 13. FIG. A heat insulating material 18 a such as urethane is disposed on the concave surface of the heat insulating portion 18, so that the frost detection sensor 13 is prevented from being influenced by heat from other than the vehicle exterior heat exchanger 4.
[0014]
Further, the attachment member 15 shown in FIGS. 5 and 6 includes an attachment main body 20, a heat insulating member 21, and an attachment plate 22. The mounting body 20 includes a locking portion 19 similar to the locking portion 17 and holds the frost detection sensor 13. The heat insulating member 21 insulates the frosting detection sensor 1 from other than the vehicle exterior heat exchanger 4 by the central portion expanding and a heat insulating material 21 a disposed on the inner surface thereof. The mounting plate 22 is disposed on the side opposite to the heat insulating member 21 with respect to the vehicle exterior heat exchanger 4, and attaches the heat insulation member 21 to the vehicle exterior heat exchanger 4 with bolts, nuts, or the like.
[0015]
As described above, the frost detection sensor 13 is attached to the vehicle exterior heat exchanger 4 at a position where the air blown from the fan 10 cannot be blown and covered with the heat insulating portion 17 or the heat insulating member 20. The frost detection sensor 13 is less susceptible to heat from other than the outside heat exchanger 4 and can detect the surface temperature of the outside heat exchanger 4 more appropriately.
[0016]
Further, the attachment position of the frost detection sensor 13 is above the substantially intermediate position of the vehicle exterior heat exchanger 4. That is, as shown in the graph of FIG. 7, the heat exchange medium suddenly flows into the outside heat exchanger 4 immediately after the start of the heating operation, so that the temperature near the inlet 9a varies, but the frost formation occurs. The detection sensor 13 is provided at a position that is not easily affected by the temperature change.
[0017]
The detected temperature of the frost detection sensor 13 is input to the frost detection control device 23. The frost detection control device 23 performs the defrosting operation according to the flowchart of FIG. 8 based on the detected temperature.
[0018]
First, when a heating switch (not shown) is turned on in step S1, heating operation is started in step S2. In this heating operation, the compressor 2 is driven in a state in which the four-way valve 1 is switched as shown by a solid line in FIG. 1, so that the heat exchange medium is the vehicle interior heat exchanger 3, the vehicle exterior heat exchanger 4, and the four-way valve 1. And circulates from the accumulator 5 to the compressor 2. As a result, the heat exchange medium that has become high temperature and high pressure in the compressor 2 dissipates heat in the vehicle interior heat exchanger 3, heats the air passing through the blower unit 11, and then absorbs heat in the vehicle exterior heat exchanger 4.
[0019]
Subsequently, in step S3, it is determined whether or not the temperature detected by the frost detection sensor 13 has fallen below a set value (set to -13 ° C. in this embodiment). In this case, immediately after the start of the heating operation, the temperature of the heat exchange medium is not stable and greatly fluctuates as shown in the graph of FIG. Although the temperature below the set value may be detected, as described above, since the frost detection sensor 13 is provided above the substantially intermediate position of the vehicle exterior heat exchanger 4, the heat exchange is always performed. It can be detected in a state where the temperature of the medium is stable.
[0020]
If the detected temperature does not decrease to the set value, the outside heat exchanger 4 determines that there is no frost and the heat exchange efficiency is sufficient, and the heating operation is continued. It is determined that the heat exchange efficiency has deteriorated, and the defrosting operation is started in step S4. In this defrosting operation, the four-way valve 1 is switched as shown by the dotted line in FIG. 1 to change the heat exchange medium in the reverse direction, that is, from the compressor 2 to the four-way valve 1, the vehicle exterior heat exchanger 4, and the vehicle interior heat exchanger 2. And circulate to the compressor 2 through the four-way valve 1 and the accumulator 5. Thereby, the heating and heat absorption states between the vehicle interior heat exchanger 3 and the vehicle exterior heat exchanger 4 are reversed, and the vehicle exterior heat exchanger 4 starts defrosting.
[0021]
Thereafter, in step S5, it is determined whether or not the defrosting is completed depending on whether or not the temperature detected by the frost detection sensor 13 is higher than a predetermined value. If the defrosting is not completed, the defrosting operation is continued. If completed, the process returns to step S2 to resume the heating operation.
[0022]
In addition, in the said Example, by starting defrost operation based on the detected temperature in the frosting detection sensor 13 provided in the upper side rather than the substantially intermediate position of the vehicle outside heat exchanger 4, it is immediately after heating operation start. Although malfunction due to variations in the temperature of the heat exchange medium is prevented, the following may be possible.
[0023]
That is, the frost determination is not performed for a predetermined time (for example, 10 minutes) immediately after the start of the heating operation. This is because immediately after the start of the heating operation, the heat exchange medium suddenly flows into the outside heat exchanger 4 and the temperature on the inflow port 9a side suddenly decreases. Therefore, as shown in the graph of FIG. This is because there is a large variation in the temperature and an appropriate temperature measurement cannot be performed.
[0024]
Even if the detected temperature is equal to or lower than the set value, the heating operation is continued if the degree of variation exceeds a certain range. This is because the fluctuation range of the detected temperature is large even though frosting has not occurred for a predetermined time after the heating operation is started.
[0025]
【The invention's effect】
As is apparent from the above description, according to the present invention, the frost detection sensor is provided at a position where the air blown from the fan and the traveling wind cannot be blown, and the temperature of the heat exchange medium does not fluctuate greatly. As a result, the surface temperature of the vehicle exterior heat exchanger can be accurately detected without fear of malfunctioning, and appropriate defrosting operation can be performed.
[0026]
Further, the defrosting operation is started only when the temperature detected by the frost detection sensor is equal to or lower than a predetermined value and the fluctuation range per unit time is within a predetermined range. Regardless of this, it is possible to reliably detect the frosting state.
Further, since the frost determination is not performed immediately after the start of the heating operation, the accuracy of the determination of the presence or absence of frost can be further increased.
[Brief description of the drawings]
FIG. 1 is a schematic view of an air conditioner for an electric vehicle according to the present embodiment.
FIG. 2 is a front view of the vehicle exterior heat exchanger of FIG. 1;
FIG. 3 is a perspective view showing a part of a frost detection sensor mounting member and a vehicle exterior heat exchanger.
4 is a perspective view showing a state in which the frost detection sensor and the attachment member of FIG. 3 are viewed from another angle.
FIG. 5 is an exploded perspective view of a mounting member of another frost detection sensor.
6 is a cross-sectional view showing a state of attachment by the attachment member of FIG.
FIG. 7 is a graph showing changes in outside air temperature and detected temperature.
FIG. 8 is a flowchart showing defrosting operation control by the frost detection control device of FIG. 1;
[Explanation of symbols]
4 ... Vehicle outside heat exchanger, 10 ... Fan, 13 ... Frosting detection sensor, 21 ... Heat insulation member.

Claims (3)

Interior heat exchanger heat exchange medium was elevated temperature and pressure in the compressor, when performing a heating operation by circulating in the order of the exterior heat exchanger, the frost detecting sensor attached to the vehicle outer side heat exchanger If frost formation of the vehicle exterior heat exchanger is detected based on the detected temperature of the vehicle, the four-way valve is switched to reversely circulate the heat exchange medium to defrost the vehicle exterior heat exchanger. In automotive air conditioners,
The frost detection sensor is located at a position where air blown from a fan provided in the vicinity of the vehicle exterior heat exchanger and running air are not blown, and immediately after the heating operation is started, the heat exchange medium is placed in the vehicle exterior heat exchanger. Provided at a position other than the range where the initial temperature disturbance that occurs when flowing in,
Even if the detected temperature from the frost detection sensor is equal to or lower than a set value at which frost formation is determined to occur in the outside heat exchanger, the heating operation is performed if the detected temperature variation degree exceeds a certain range. An air conditioner for an electric vehicle, characterized in that a defrost control means for continuing the operation is provided.   The air conditioner for an electric vehicle according to claim 1, wherein the frost sensor is covered with a heat insulating member that blocks a thermal influence from other than the outside heat exchanger.   3. The electric vehicle air conditioner according to claim 1, further comprising a defrosting control unit configured to perform frosting determination after a predetermined time has elapsed from the start of the heating operation.

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