JPH07151426A - Air conditioner - Google Patents

Abstract

PURPOSE:To provide an air conditioner in which a defrosting control is so conducted in a short time as not to lower heating capacity when only an inlet of an outdoor heat exchanger is frosted without losing comfortableness. CONSTITUTION:When frosting of an outdoor heat exchanger is judged based on a decrease in heating capacity and frosting of only an inlet of the exchanger is detected, a defrosting two-way valve 7 is opened to supply high temperature and high pressure refrigerant from a compressor 2 to the inlet of the exchanger 5, thereby defrosting the exchanger 5 for a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner using a non-azeotropic mixed refrigerant.

[0002]

2. Description of the Related Art As an air conditioner using this type of non-azeotropic mixed refrigerant, there is one having a refrigeration cycle as shown in FIG. In FIG. 7, the outdoor unit 1 is composed of main components such as a compressor 2, a four-way valve 3, an expansion valve 4, an outdoor heat exchanger 5, an outdoor heat exchanger temperature sensor 6, and a defrosting two-way valve 7. The indoor unit 10 includes main components such as an indoor heat exchanger 11 and an indoor heat exchanger temperature sensor 12.

In the conventional air conditioner thus constructed, in the heating operation, the high-temperature and high-pressure refrigerant gas compressed by the compressor 2 is guided to the indoor unit 10 after passing through the four-way valve 3. While flowing through the heat exchanger 11, it exchanges heat with the indoor air by an indoor blower (not shown), so that heat is released into the room and condensed. Then, the liquefied refrigerant returns to the outdoor unit 1, is decompressed by the expansion valve 4, and then exchanges heat with the outdoor air by an outdoor blower (not shown) in the outdoor heat exchanger 5 to complete the evaporation process. The heated refrigerant gas enters the compressor 2 again,
The high-temperature high-pressure refrigerant gas is discharged and discharged, and one cycle during heating is completed. When the outdoor heat exchanger 5 is frosted at a low outdoor temperature, the defrosting two-way valve 7 is opened, whereby the high-temperature and high-pressure refrigerant from the compressor 2 is passed through the defrosting two-way valve 7. The heat is supplied to the outdoor heat exchanger 5 to remove frost from the outdoor heat exchanger 5.

In the above-mentioned air conditioner, when a non-azeotropic mixed refrigerant is evaporated at a constant pressure, unlike a single refrigerant, the composition of the refrigerant changes as it evaporates.
Evaporation temperature rises. Therefore, even if the pressure inside the outdoor heat exchanger 5 which is an evaporator is constant, the temperature of the inlet portion 5a near the expansion valve 4 becomes lower than the temperature of the outlet portion 5b near the four-way valve 3. To do. As a result, during the heating operation, it freezes from the inlet portion 5a of the outdoor heat exchanger 5 and frost adheres to it, and the effective area of the heat exchanger that can be used as an evaporator decreases with the passage of time. As shown, it will cause a decline in ability. Then, defrost control is performed in order to remove the adhered frost, but when the defrost control is entered during the heating operation, the blowing temperature and the room temperature are lowered.

[0005]

As described above, in the air conditioner using the non-azeotropic mixed refrigerant, the temperature of the inlet of the outdoor heat exchanger, which is the evaporator, becomes lower than the temperature of the outlet thereof. As a result, frost adheres, and defrost control is often performed for this reason. However, when defrost control is performed, there is a problem in that the heating capacity is reduced and the user feels uncomfortable.

The present invention has been made in view of the above,
The purpose is to provide an air conditioner that does not impair comfort by performing defrosting control for a short time so as not to reduce heating capacity when only the inlet of the outdoor heat exchanger is frosted. .

[0007]

In order to achieve the above object, an air conditioner of the present invention comprises an outdoor unit having a compressor, a four-way valve, an expansion valve and an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger. An air conditioner using a non-azeotropic mixed refrigerant as a refrigerant, comprising: a temperature detecting means for detecting a temperature at a predetermined point between a heating side inlet of the outdoor heat exchanger and an intermediate portion thereof; , The temperature detected by the temperature detecting means is the first
When the temperature of the outdoor heat exchanger starts to defrost, the defrosting means ends the defrosting when the temperature detected by the temperature detecting means rises to the second predetermined temperature. Having it is the gist.

Further, the air conditioner of the present invention comprises a compressor,
An air conditioner comprising an outdoor unit having a four-way valve, an expansion valve and an outdoor heat exchanger and an indoor unit having an indoor heat exchanger, wherein the outdoor heat exchanger is a non-azeotropic mixed refrigerant. When it is determined that the outdoor heat exchanger is frosted based on the determination result of the determination means for determining the reduction of the heating capacity to identify whether or not frost is formed, the outdoor heat exchanger Detecting that only the inlet of the outdoor heat exchanger is frosted and that the outlet is not frosted and the outlet is not frosted. In that case, the gist of the present invention is to have a defrosting means for supplying high-temperature and high-pressure refrigerant from the compressor to the inlet of the outdoor heat exchanger to defrost the outdoor heat exchanger for a short time.

Further, in the air conditioner of the present invention, in the above-mentioned constitution, the judging means detects the temperature of the indoor heat exchanger or the blowing temperature of the indoor heat exchanger by the temperature detecting means and the temperature detecting means. It is a gist to have a heating capacity reduction identifying means for identifying a reduction in heating capacity based on temperature.

Further, in the air conditioner of the present invention, in the above structure, the detecting means is provided at the inlet of the outdoor heat exchanger, and the inlet temperature detecting means for detecting the temperature of the inlet,
An outlet temperature detection means, an inlet temperature detection means, and an outlet temperature detection means, which are provided at a point somewhere from the intermediate portion to the outlet portion of the outdoor heat exchanger and detect a temperature at some point from the intermediate portion to the outlet portion. The gist of the present invention is to have an inlet portion frost formation determining means for determining that only the inlet portion of the outdoor heat exchanger is frosted and the outlet portion is not frosted on the basis of the temperatures respectively detected in.

In the air conditioner of the present invention, in the above structure, the defrosting means performs defrosting for a predetermined time, means for performing defrosting until the freezing of the inlet of the outdoor heat exchanger is thawed, At least a group consisting of means for performing defrosting until the temperature of the indoor heat exchanger drops below a predetermined temperature, and means for performing defrosting until the blowout temperature of the outdoor heat exchanger falls below a predetermined temperature. The gist is to have one means.

[0012]

In the air conditioner of the present invention, the temperature at a predetermined point between the heating-side inlet of the outdoor heat exchanger and the intermediate portion is detected, and when the detected temperature drops to the first predetermined temperature,
When the defrosting of the outdoor heat exchanger is started and the detected temperature rises to the second predetermined temperature, the defrosting is ended.

Further, in the air conditioner of the present invention, it is determined that the outdoor heat exchanger has frosted on the basis of the reduction of the heating capacity,
Further, when it is detected that only the inlet portion of the outdoor heat exchanger is frosted, the outdoor heat exchanger is defrosted for a short time.

Further, in the air conditioner of the present invention, the reduction of the heating capacity is identified based on the temperature of the indoor heat exchanger or the blowing temperature of the indoor heat exchanger.

Furthermore, in the air conditioner of the present invention, the outdoor heat exchange is carried out based on the temperature of the inlet of the outdoor heat exchanger and the temperature of any one point between the substantially middle portion and the outlet of the outdoor heat exchanger. It is determined that only the inlet part of the vessel is frosted and the outlet part is not frosted.

In the air conditioner of the present invention, short-time defrosting is performed by defrosting for a predetermined time, defrosting until the freezing of the inlet of the outdoor heat exchanger is thawed, or indoor heat exchange. The defrosting is performed until the temperature of the vessel drops below a predetermined temperature, or the defrosting is performed until the blowout temperature of the outdoor heat exchanger falls below a predetermined temperature.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of a refrigeration cycle of an air conditioner according to an embodiment of the present invention. The air conditioner shown in FIG. 1 uses a non-azeotropic mixed refrigerant as a refrigerant, but is composed of an indoor unit 10 and an outdoor unit 20, and the indoor unit 10 includes an indoor heat exchanger 11 and an indoor heat exchanger 11.
The outdoor unit 20 is composed of main components such as an indoor heat exchanger temperature sensor 12 that detects the temperature of the outdoor heat exchanger, and the outdoor unit 20 includes a compressor 2, a four-way valve 3, an expansion valve 4, an outdoor heat exchanger 5, and heating of the outdoor heat exchanger 5. A temperature sensor 31, which is provided at an intermediate point which is a predetermined point between the side inlet and the intermediate portion, detects the temperature of the intermediate point, and is connected between the outlet of the compressor 2 and the inlet of the outdoor heat exchanger 5. It is composed of main components such as the defrosted two-way valve 7 and the like.

In the air conditioner thus constructed, the temperature sensor 31 is provided at the intermediate point, which is a predetermined point between the heating-side inlet of the outdoor heat exchanger 5 and the intermediate section, whereby the intermediate point of the intermediate point is provided. The temperature is detected, and defrosting is started and ended based on the detected temperature at the intermediate point.

That is, the temperature at the intermediate point detected by the temperature sensor 31 is slightly higher than 0 ° C. at the beginning of heating operation, as shown in FIG.
As described above, when the heating operation is performed using the non-azeotropic mixed refrigerant, the temperature of the inlet of the outdoor heat exchanger 5 becomes lower than the temperature of the outlet thereof, and the temperature of the inlet becomes as shown in FIG. As shown, the temperature gradually decreases to 0 ° C. or lower, freezes from the inlet portion, and frost starts to adhere to the inlet portion.

Therefore, the temperature sensor 31 detects the temperature of the intermediate point near the inlet of the outdoor heat exchanger 5, and the detected temperature becomes the first predetermined temperature of 0 ° C. or less shown by X in FIG. If it becomes, defrost control is started. When this defrosting control is started, the frost attached to the inlet of the outdoor heat exchanger 5 is gradually melted, and the temperature at the midpoint of the outdoor heat exchanger 5 detected by the temperature sensor 31 is shown in FIG. As described above, when the detected temperature exceeds 0 ° C. and reaches the second predetermined temperature indicated by Y in FIG. 2, the defrosting is ended, so that the outdoor heat exchanger 5 Frost at the entrance can be removed properly.

Defrosting at the inlet of the outdoor heat exchanger 5
This can be performed by supplying the high-temperature and high-pressure refrigerant from the compressor 2 to the inlet of the outdoor heat exchanger 5 via the defrosting two-way valve 7.

FIG. 3 is a diagram showing the structure of a refrigerating cycle of an air conditioner according to another embodiment of the present invention. The air conditioner shown in FIG. 3 uses a non-azeotropic mixed refrigerant as the refrigerant as in FIG. 1, but is composed of an indoor unit 10 and an outdoor unit 100, and the indoor unit 10 has an indoor heat exchanger 11,
The indoor heat exchanger 11 is composed of main components such as an indoor heat exchanger temperature sensor 12 for detecting the temperature of the indoor heat exchanger 11 and an outlet temperature sensor 13 for detecting the outlet temperature of the indoor heat exchanger 11. The valve 3, the expansion valve 4, the outdoor heat exchanger 5, the first temperature sensor 61 provided on the inlet side of the outdoor heat exchanger 5, and one point provided between the approximately middle portion and the outlet portion of the outdoor heat exchanger 5. Second temperature sensor 62, a third temperature sensor 63 provided inside the outdoor heat exchanger 5, and defrosting connected between the outlet of the compressor 2 and the inlet of the outdoor heat exchanger 5. It is composed of main parts such as the two-way valve 7.

The air conditioner of this embodiment having the above-described structure is different from the conventional air conditioner shown in FIG. 7 in that the first and second temperature sensors 61 and 62 and the blowing temperature sensor 13 are provided. Is very different. As described in the related art, the defrosting two-way valve 7 is opened when the inlet portion of the outdoor heat exchanger 5 is frosted by performing the heating operation using the non-azeotropic mixed refrigerant. As a result, the high temperature and high pressure refrigerant from the compressor 2 is transferred to the defrosting two-way valve 7
Is supplied to the inlet part of the outdoor heat exchanger 5 via the heat exchanger to remove frost from the inlet part of the outdoor heat exchanger 5.

FIG. 4 is a frosting state determination diagram by the first, second and third temperature sensors 61, 62 and 63, in which the horizontal axis indicates from the inlet side to the outlet side of the outdoor heat exchanger 5. Positions are shown, and the temperature at each of these positions is shown on the vertical axis. Further, the horizontal axis represents the position of the first temperature sensor 61 located on the inlet side of the outdoor heat exchanger 5, and the second temperature sensor 62 located between approximately the middle portion and the outlet portion of the outdoor heat exchanger 5. , And the position of the third temperature sensor 63 located inside the outdoor heat exchanger 5, and the temperatures detected by the temperature sensors 61, 62, 63 at these positions are shown.

In this way, the temperature sensors 61, 62, 63
Detects the temperature of each of the inlet portion, the intermediate portion and the outlet portion of the outdoor heat exchanger 5, and the inside temperature. In particular, the first and second temperature sensors 61 and 62 are provided.
Constitutes a frost detection means for determining the frosted state of the outdoor heat exchanger 5 from these detected temperatures.

As can be seen from FIG. 4, the temperature at the inlet of the outdoor heat exchanger 5 detected by the first temperature sensor 61 is the middle of the temperature of the outdoor heat exchanger 5 detected by the second temperature sensor 62. It is as described in the prior art that the temperature is lower than the temperature at some point from the section to the outlet section. Figure 4
In (2), the line indicated by (1) shows the characteristics during normal operation when the outdoor heat exchanger is not frozen, and the line indicated by (2) shows that only the inlet part of the outdoor heat exchanger 5 is frozen and frosted. Shows the characteristics when the inlet part is frozen, and the line shown in (3) is the outdoor heat exchanger 5
Shows the characteristics when is completely frozen and frosted.

The frost formation detecting means which is composed of the temperature sensors 61 and 62 has a temperature t _{1 at} the inlet of the outdoor heat exchanger 5 detected by the first temperature sensor 61 and a second temperature sensor 6
Assuming that the temperature at some point from the intermediate portion to the outlet portion of the outdoor heat exchanger 5 detected at ₂ is t ₂ , if t ₁ > 0 and t ₂ > 0, the outdoor heat exchanger 5 is frosted. If t ₁ <0 and t ₂ > 0, it is determined that only the inlet of the outdoor heat exchanger 5 is frosted, and t ₁ <0 and t ₂
When <0, it is determined that the outdoor heat exchanger 5 is entirely frosted.

Next, the operation will be described.

First, during the normal heating operation shown by the characteristic (1) in FIG. 4, the expansion valve 4 is set to the throttle of the refrigeration cycle,
The defrosting two-way valve 7 is set to the closed state. In the state set as described above, the high-temperature and high-pressure refrigerant gas compressed by the compressor 2 is guided to the indoor unit 10 after passing through the four-way valve 3, and is not illustrated while flowing through the indoor heat exchanger 11. By exchanging heat with the indoor air by the indoor blower, heat is released into the room and condensed. Then, the liquefied refrigerant returns to the outdoor unit 100, is decompressed by the expansion valve 4, and then exchanges heat with the outdoor air by an outdoor blower (not shown) while flowing through the outdoor heat exchanger 5, thus completing the evaporation process. The heated refrigerant gas enters the compressor 2 again, and is discharged as high-temperature and high-pressure refrigerant gas.

Next, the operation at the time of defrosting the inlet portion shown by the characteristic (2) in FIG. 4 will be described with reference to the flow chart shown in FIG.

In FIG. 5, first, it is checked whether or not the heating capacity of the air conditioner has decreased to determine whether or not the outdoor heat exchanger 5 has frosted (step 110).

The determination of the decrease of the heating capacity is made by the indoor heat exchanger temperature sensor 1 attached to the indoor heat exchanger 11.
2 or the temperature of the indoor heat exchanger 11 detected by the indoor heat exchanger temperature sensor 12 or the indoor heat exchanger 1 detected by the blowing temperature sensor 13 using the blowing temperature sensor 13
This is performed depending on whether or not the blowout temperature of 1 has dropped. That is, in general, the air conditioner does not change the operating frequency and the air volume, and when the heat load does not change, the temperature of the indoor heat exchanger 11 or the blowing temperature hardly changes. When the temperature of the indoor heat exchanger 11 or the blowing temperature changes, the outdoor heat exchanger 5 is frosted, so that the effective area that can be used as a heat exchanger is reduced, and thus the reduction in capacity is started. it is conceivable that.

When a decrease in heating capacity is detected based on the decrease in the temperature detected by the indoor heat exchanger temperature sensor 12 or the blowout temperature sensor 13 as described above, the inlet of the outdoor heat exchanger 5 which functions as an evaporator. It is checked whether the copy is frozen (step 120). As described with reference to FIG. 4, the first temperature sensor 61 provided at the inlet of the outdoor heat exchanger 5 determines whether the inlet of the outdoor heat exchanger 5 is frozen. It is performed depending on whether the detected temperature of the inlet portion is 0 ° C. or lower.

When the temperature of the inlet of the outdoor heat exchanger 5 detected by the first temperature sensor 61 is 0 ° C. or lower and it is detected that the inlet of the outdoor heat exchanger 5 is frozen, The check whether the outlet of the outdoor heat exchanger 5 is frozen is based on the temperature at one point from the intermediate portion of the outdoor heat exchanger 5 to the outlet detected by the second temperature sensor 62. The same is done (step 130). When the temperature at some point from the intermediate portion to the outlet portion detected by the second temperature sensor 62 is not 0 ° C. or lower and it is not frozen, the process proceeds to step 140, and the defrosting control is performed for a short time (step When the defrosting control is completed for a short time 140), the defrosting control is returned (step 150) and the normal operation is resumed (step 170).

In this short-time defrosting control, the high-temperature and high-pressure refrigerant from the compressor 2 is opened in the outdoor heat exchanger 5 by opening the defrosting two-way valve 7. It is supplied to the inlet part, thereby performing hot gas defrosting, and the outdoor heat exchanger 5
Remove the frost at the entrance of the. As shown in FIG. 6, this defrosting control is performed for a short time so as not to give a user an unpleasant feeling, but this short-time defrosting control is performed for a defrosting time of, for example, 30 seconds or 60 seconds. Such a predetermined time is determined in advance, and the first method of performing only during this short defrosting time is that the frost at the inlet of the outdoor heat exchanger 5 has melted.
Second method carried out until the temperature sensor 61 detects the temperature t ₃ detected by the third temperature sensor 63 of the outdoor heat exchanger 5, and the third method carried out until the temperature t ₃ detected by the third temperature sensor 63 of the outdoor heat exchanger 5 becomes higher than 0. A fourth method, which is implemented by returning from the defrost control when the temperature of the indoor heat exchanger 11 detected by the indoor heat exchanger temperature sensor 12 of the indoor heat exchanger 11 falls below a predetermined temperature, There is a fifth method or the like that is executed by returning from the defrosting control when the blowout temperature of the indoor heat exchanger 11 detected by the blowout temperature sensor 13 of the heat exchanger 11 falls below a predetermined temperature.

In the fourth and fifth methods described above, when the temperature of the indoor heat exchanger 11 or the blowing temperature is lowered, the comfort of the user is taken into consideration so that the user does not feel cold. In addition, when the indoor heat exchanger temperature or the blowout temperature becomes equal to or lower than a predetermined temperature, the defrosting control is restored.

On the other hand, as a result of the check in step 130,
The temperature of one point from the intermediate portion of the outdoor heat exchanger 5 to the outlet portion detected by the second temperature sensor 62 is 0 ° C. or lower, and the outlet portion of the outdoor heat exchanger 5 is also frozen. If it is detected, the outdoor heat exchanger 5 is in a state of being completely frozen and frosted, so the routine proceeds to step 160, where normal defrosting control is carried out, and the entire surface of the outdoor heat exchanger 5 is After defrosting is released, normal operation is resumed (step 17
0).

[0039]

As described above, according to the present invention,
The temperature at a predetermined point between the heating-side inlet of the outdoor heat exchanger and the intermediate portion is detected by the temperature detecting means, and the detected temperature is the first temperature.
When the detected temperature rises to a second predetermined temperature, the defrosting of the outdoor heat exchanger is started when the temperature drops to a predetermined temperature of 1. 1
Defrosting can be performed relatively easily and easily by the individual temperature detecting means, and economic efficiency can be achieved, and since the defrosting time is relatively short, without causing discomfort to the user, Can be defrosted.

Further, according to the present invention, when it is determined that the outdoor heat exchanger is frosted on the basis of the reduction of the heating capacity, and it is further detected that only the inlet portion of the outdoor heat exchanger is frosted. Since the outdoor heat exchanger is defrosted for a short time, it is possible to prevent the average heating capacity from being reduced and to defrost the user without causing discomfort.

Further, according to the present invention, the reduction of the heating capacity is identified based on the temperature of the indoor heat exchanger or the blowing temperature of the indoor heat exchanger, and only the inlet portion of the outdoor heat exchanger is frosted,
The outlet part determines whether or not frost has formed, based on the temperature at the inlet part of the outdoor heat exchanger and the temperature at a point somewhere from approximately the middle part of the outdoor heat exchanger to the outlet part. As the frost, for example, defrosting is performed for a predetermined time such as 30 or 60 seconds, defrosting is performed until the freezing of the inlet of the outdoor heat exchanger is thawed, and the temperature of the indoor heat exchanger is kept below a predetermined temperature. The defrosting is performed until the temperature drops, or the defrosting is performed until the blowout temperature of the outdoor heat exchanger drops below a predetermined temperature, and the comfort is controlled not to be impaired.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a refrigeration cycle of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a temperature change detected by a temperature sensor used in the embodiment shown in FIG.

FIG. 3 is a diagram showing a configuration of a refrigeration cycle of an air conditioner according to an embodiment of the present invention.

FIG. 4 is a frosting state determination diagram by a temperature sensor used in the air conditioner shown in FIG.

5 is a flow chart showing the operation of the air conditioner shown in FIG.

FIG. 6 is a diagram showing changes in heating capacity of the air conditioner shown in FIG. 3 with respect to time.

FIG. 7 is a diagram showing a configuration of a refrigeration cycle of a conventional air conditioner.

FIG. 8 is a diagram showing a change in capacity with time in a conventional air conditioner.

[Explanation of symbols]

 2 Compressor 3 Four-way valve 4 Expansion valve 5 Outdoor heat exchanger 7 Defrosting two-way valve 10 Indoor unit 11 Indoor heat exchanger 12 Indoor heat exchanger temperature sensor 13 Blowing temperature sensor 31, 61, 62, 63 Temperature sensor 100 Outdoor unit

Claims (5)

[Claims] 1. An air conditioner comprising a compressor, a four-way valve, an expansion valve, an outdoor unit having an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger, wherein a non-azeotropic mixed refrigerant is used as a refrigerant. Then, the temperature detecting means for detecting the temperature at a predetermined point between the heating-side inlet of the outdoor heat exchanger and the middle part, and the temperature detected by the temperature detecting means are lowered to the first predetermined temperature. In this case, air having defrosting means for starting defrosting of the outdoor heat exchanger and ending the defrosting when the temperature detected by the temperature detecting means rises to a second predetermined temperature. Harmony device. 2. An air conditioner comprising a compressor, a four-way valve, an expansion valve, an outdoor unit having an outdoor heat exchanger and an indoor unit having an indoor heat exchanger, and using a non-azeotropic mixed refrigerant as a refrigerant. Therefore, it is determined that the outdoor heat exchanger is frosted based on the determination result of the determination means for determining the reduction of the heating capacity in order to identify whether the outdoor heat exchanger has frosted or not. In the case where only the inlet part of the outdoor heat exchanger is frosted and the outlet part is not frosted, only the inlet part of the outdoor heat exchanger is detected based on the detection result and the detection result of the detector. When it is detected that frost is formed, it has a defrosting means for supplying a high-temperature and high-pressure refrigerant from the compressor to the inlet of the outdoor heat exchanger to defrost the outdoor heat exchanger for a short time. An air conditioner characterized by the above. 3. The temperature determining means for detecting the temperature of the indoor heat exchanger or the blowout temperature of the indoor heat exchanger, and the heating means for identifying the reduction in heating capacity based on the temperature detected by the temperature detecting means. The air conditioner according to claim 2, further comprising a capacity reduction identifying means. 4. The inlet means for detecting the temperature of the inlet provided in the inlet of the outdoor heat exchanger, the detecting means, one point between the intermediate portion of the outdoor heat exchanger and the outlet. An inlet of the outdoor heat exchanger is provided based on the temperature detected by the outlet temperature detecting means for detecting the temperature of one point between the intermediate portion and the outlet portion, the inlet temperature detecting means and the outlet temperature detecting means. The air conditioner according to claim 2 or 3, further comprising an inlet frost formation determining unit that determines that only one portion is frosted and that the outlet portion is not frosted. 5. The defrosting means is means for performing defrosting for a predetermined time, means for performing defrosting until the freezing of the inlet of the outdoor heat exchanger is thawed, and the temperature of the indoor heat exchanger is below a predetermined temperature. At least one of a group consisting of means for performing defrosting until the temperature drops to a certain level, and means for performing defrosting until the blow-out temperature of the outdoor heat exchanger drops below a predetermined temperature. Claim 2, 3 or 4
The air conditioner described.