JPH08327194A - Air conditioner - Google Patents

Abstract

PURPOSE: To shorten a defrosting time and improve a comfortable feeling by a method wherein a mechatronics defrosting, a quick defrosting and a reverse defrosting operation are selected in response to a refrigerant discharging temper ature of a compressor. CONSTITUTION: There is provided a freezing cycle in which an indoor heat exchanger 5 having at least a compressor 2, a four-way valve 3 and an indoor fan 4, and an outdoor heat exchanger 8 having an expansion valve 6 and an outdoor fan 7 are connected in sequence by a refrigerant pipe. There are also provided a discharging temperature sensor 11 for use in detecting a refrigerant discharging temperature of a refrigerant discharged from the compressor 2 and a control means for performing either the mechatronics defrosting operation or the quick defrosting operation and for transferring one defrosting operation to the reverse defrosting operation in response to the discharging temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner, and more particularly to an air conditioner having an improved defrosting operation method.

[0002]

2. Description of the Related Art Conventionally, there are a reverse defrosting method, a mechatronic defrosting method, a quick defrosting method, etc. as a defrosting method for this type of air conditioner. Regardless of the amount of frost formed on the heat exchanger, each is operating independently. In the above reverse defrosting method, the four-way valve that is on during the heating operation is reversed to be turned off so that the refrigerant circulation direction is reversed from that during heating, and the opening degree of the expansion valve, which is the flow rate control valve (mechatronic valve), is the predetermined opening degree. This is a method of controlling so that the temperature is kept constant by, and stopping the operation of the indoor and outdoor fans.

That is, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor is introduced into the outdoor heat exchanger, where it is radiated and liquefied, and the radiated heat heats the frost on the outer surface of the outdoor heat exchanger. It defrosts by melting frost. Further, the liquid refrigerant liquefied in the outdoor heat exchanger flows into the indoor heat exchanger through the expansion valve, is evaporated and vaporized there, becomes a gas refrigerant, and is returned to the compressor again. Therefore, the amount of liquid bag returning to the compressor as the liquid refrigerant is small.

On the other hand, the mechatronic defrosting method is to open the expansion valve while keeping the four-way valve in the on state without turning it off during the heating operation, while simply stopping the operation of the indoor and outdoor fans. Is used to heat and frost the frost on the outdoor heat exchanger to defrost it.

Therefore, the high-temperature and high-pressure refrigerant discharged from the compressor flows into the outdoor heat exchanger through the four-way valve, the indoor heat exchanger, and the expansion valve in order, and a part of the refrigerant radiates heat in the outdoor heat exchanger. By defrosting the frost, the liquid refrigerant liquefied by the defrost is returned to the compressor, where it absorbs heat, is compressed again, and is discharged. For this reason, the compressor is cooled by the liquid refrigerant sucked inside,
The temperature gradually decreases.

Further, in the quick defrosting method, the discharge side of the compressor is discharged by opening a two-way valve in a bypass passage that communicates with the refrigerant inlet side of the outdoor heat exchanger during heating. By introducing a part of the high-temperature and high-pressure gaseous refrigerant into the outdoor heat exchanger through the bypass passage, the frost adhering to the outer surface of the outdoor heat exchanger is heated and melted to defrost.

[0007]

However, in such a reverse defrosting method, since the liquefied refrigerant flowing into the indoor heat exchanger evaporates and absorbs heat, the indoor heat exchanger is cooled. For this reason, after the reverse defrosting operation is completed, it takes several minutes to warm the indoor heat exchanger and start the heating operation. That is, there is a problem that the start-up of heating operation is delayed. Also, the refrigerant temperature of the outdoor heat exchanger during reverse defrosting gradually decreases from the gas line side (defrosting inflow side) to the liquid line side (defrosting outflow side) due to the melting of frost, so the amount of frost formation is If it is large, frost may remain on the end on the liquid line side.

Further, since the four-way valve is turned off almost at the same time as the reverse defrosting operation is started, the heat of the high temperature and high pressure refrigerant accumulated in the indoor heat exchanger is dissipated in the refrigerant pipe and the suction cup, and the defrosting is performed. There is a problem that it is not used for.

Further, in the mechatronic defrosting and quick defrosting methods, since the frost of the outdoor heat exchanger is heated and melted by the amount of heat stored in the compressor and the amount of heat of its input (electric power) to defrost, During defrosting, when the amount of heat stored in the compressor almost disappears and the compressor cools down, the only heat source that can be supplied for defrosting the compressor is the input (electric power). A liquid discharge phenomenon may occur in which the liquid refrigerant accumulates in the machine and finally the liquid refrigerant and the lubricating oil in the compressor are discharged, and the compressor may fail.

Therefore, an object of the present invention is to select and execute mechatronic defrosting, quick defrosting, or reverse defrosting operation in accordance with the refrigerant discharge temperature of the compressor, thereby shortening the defrosting operation time and making it comfortable. It is to provide an air conditioner that can improve the performance.

[0011]

According to the first aspect of the present invention,
An air conditioner having a refrigeration cycle in which an indoor heat exchanger having at least a compressor, a four-way valve, an indoor fan, an expansion valve, and an outdoor heat exchanger having an outdoor fan are sequentially connected by a refrigerant pipe, A discharge temperature temperature sensor for detecting the discharge temperature of the refrigerant discharged from the air conditioner, and the expansion valve is opened while the circulation direction of the refrigerant circulating in the refrigeration cycle is the same as in the heating operation, and the indoor and outdoor fans are operated. Defrosting to stop mechatronics, or to operate either defrosting of quick defrosting to introduce a part of the refrigerant discharged from the compressor into the outdoor heat exchanger during heating operation, and the discharge temperature. Depending on the discharge temperature detected by the sensor, the circulation direction of the refrigerant circulating in the refrigeration cycle from one defrosting operation is opposite to that in the heating operation and Among comprises control means allowed to shift to the reverse defrosting operation allowed to stop the operation of the outer fan, a.

According to a second aspect of the invention, in the air conditioner according to the first aspect, the control means reverses from the mechatronic defrosting operation or the quick defrosting operation when the detected value of the discharge temperature is higher than a predetermined value. This is a configuration for shifting to the defrosting operation.

According to a third aspect of the invention, in the air conditioner according to the second aspect, the control means returns to the heating operation when the discharge temperature detected during the defrosting operation falls below a first predetermined value. It is a configuration that allows it.

The invention according to claim 4 is the invention according to claim 2 or 3.
In the air conditioner described above, the control means is configured to return to the heating operation when the discharge temperature detected during the defrosting operation rises by a predetermined value above the stored minimum discharge temperature during the defrosting operation.

The invention according to claim 5 is the air conditioner according to any one of claims 1 to 4, wherein the control means is:
Instead of the discharge temperature, any one of the compressor case temperature, which is the compressor case temperature, the degree of dilution, and the difference between the compressor case temperature and the saturation temperature of the high-pressure reference of the refrigerant is used as a criterion.

[0016]

According to the first to fifth aspects of the invention, the discharge temperature detected by the discharge temperature sensor, the compressor case temperature,
When the degree of dilution, Δt, etc. is high, the heat storage amount of the compressor is large and the compressor is at a high temperature. Therefore, the control means performs defrosting based on the heat storage amount of the compressor, or mechatronic defrosting or quick defrosting. Be driven. Thus, the high-temperature and high-pressure gaseous refrigerant that has absorbed the heat accumulated in the compressor can be introduced into the outdoor heat exchanger through the indoor heat exchanger to defrost the frost. Moreover, since defrosting is performed while the temperature of the indoor heat exchanger remains high, startup can be accelerated when heating operation is restarted, and comfort can be improved.

When the compressor is gradually cooled by the operation of the mechatronic defrosting or the quick defrosting, and the heat storage amount is gradually reduced to lower the refrigerant discharge temperature of the compressor, the four-way valve is turned off by the control means. Is reversed to switch to reverse defrosting operation. As a result, all of the high-temperature and high-pressure gaseous refrigerant from the compressor is directly introduced into the outdoor heat exchanger to radiate heat and defrost. The liquid refrigerant that radiates heat and liquefies in the outdoor heat exchanger evaporates and absorbs heat in the indoor heat exchanger and is returned to the compressor in a gas state. Therefore, since the refrigerant absorbs heat in the indoor heat exchanger, the supply heat source for defrosting is not insufficient, and the refrigerant is returned to the compressor in a gas state, so that the amount of liquid back is small. Therefore, the compressor is less likely to be hindered and its reliability can be improved.

According to the third aspect of the present invention, by the mechatronics or quick defrosting operation, the heat storage amount of the compressor is reduced by the liquid back and the temperature of the compressor is gradually lowered, and the compressor detected by the discharge temperature sensor. The first refrigerant discharge temperature is
When the temperature falls below a predetermined value of, the defrosting operation is forcibly terminated and the heating operation is restored.

As a result, the temperature of the compressor can be maintained above the first predetermined value at all times, so that ΔT, which is the difference between the compressor case temperature and the saturation temperature based on the high pressure, can always be secured during defrosting. Therefore, it is possible to effectively prevent the deterioration of the lubricating performance of the lubricating oil in the compressor due to the decrease of ΔT and the liquid discharge of discharging the gas-liquid two-phase refrigerant mixed with the lubricating oil. The reliability can be improved.

According to the fourth aspect of the present invention, the amount of heat stored in the compressor is gradually reduced by the liquid back due to the mechatronics or quick defrosting operation, and the temperature of the compressor is gradually lowered. 2 from the stored minimum discharge temperature
When the predetermined value such as deg rises, the defrosting operation is forcibly ended by the control means and the heating operation is restored.
Therefore, also in the present invention, since the temperature of the compressor can be always kept constant as in the case of the third aspect of the invention, each inconvenience caused by the decrease in ΔT is effectively prevented and the reliability is improved. be able to.

[0021]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a refrigeration cycle diagram of an embodiment of an air conditioner according to the present invention. In this figure, an air conditioner 1 is a compressor 2, which is driven by an inverter (not shown) so that the rotation speed can be controlled freely. An indoor heat exchanger having a four-way valve 3, an indoor fan 4, an expansion valve 6, which is a flow control valve (mechatronic valve) 6, an outdoor heat exchanger 8 having an outdoor fan 7, and a refrigerant pipe 9
Thus, the refrigerating cycle in which the refrigerant is reversibly circulated is sequentially connected in this order and in a ring shape. In this refrigeration cycle, when the indoor and outdoor fans 4 and 7 are operating, the refrigerant is circulated in the direction of the solid line arrow in the figure by the switching operation of the four-way valve 3, and is circulated in the direction of the broken line arrow in the figure. The cooling operation is performed by. Further, at least when the indoor and outdoor fans 4 and 7 are stopped, the refrigerant is circulated in the direction of the solid line arrow to perform the mechatronics defrosting operation, and by being circulated in the direction of the broken line arrow to perform the reverse defrosting operation. It

The outdoor heat exchanger 8 is provided with an evaporation temperature sensor 10 for detecting the evaporation temperature TE of the refrigerant evaporated in the outdoor heat exchanger 8, while the discharge temperature of the refrigerant is set on the discharge side of the compressor 2. A discharge temperature sensor 11 for detecting is provided, and these two sensors 10, 11 are electrically connected to an outdoor controller 12 which is a control means by a signal line.

The outdoor controller 12 is composed of, for example, a microprocessor and the like, and during the heating operation, according to the first control program shown in FIG. 2, the discharge temperature Td of the refrigerant read from the discharge temperature sensor 11 and the evaporation temperature sensor 10 are read. The necessity of defrosting is judged based on the refrigerant refrigerant evaporation temperature TE to perform the mechatronic defrosting, and further,
The mechatronics defrosting operation is switched to the reverse defrosting operation.

Next, the first control program of the outdoor controller 12 will be described with reference to the flowchart of FIG. Note that S1 to S7 in FIG. 2 indicate steps of the flowchart.

First, when the outdoor controller 12 starts the heating operation of the air conditioner 1 in S1, the evaporation temperature TE of the refrigerant evaporated in the outdoor heat exchanger 8 read from the evaporation temperature sensor 10 in S2. For example, lower than -2 ° C (TE <-
2) It is repeatedly judged whether or not the state continues for 30 minutes, and if Yes, it is judged that defrosting of the outdoor heat exchanger 8 is necessary, and the refrigerant discharge temperature Td read from the discharge temperature sensor 11 in S3. Is, for example, 50 ° C or higher (Td ≦ 50)
If Yes, it is determined that the heat storage amount of the compressor 2 is large, and the mechatronics defrosting operation is selected and executed in S4. If No, the heat storage amount of the compressor 2 is small. The reverse defrosting operation is selected and executed in S5.

In the mechatronic defrosting of S4, even if the defrosting operation is started as shown in the sequence of FIG. 3, the four-way valve 3 is not turned from ON to OFF but is kept in the ON state, while the expansion valve is opened. This is different from the reverse defrosting operation in that the opening of No. 6 is controlled to be fully opened or close to it.

Therefore, the circulation direction of the refrigerant is the same as that during the heating operation as shown by the solid arrow in FIG. For this reason, the high-temperature and high-pressure gaseous refrigerant from the compressor 2 is guided by the four-way valve 3 which is on, sequentially flows through the indoor heat exchanger 5 and the expansion valve 6, and then flows into the outdoor heat exchanger 8. At this time, since the operation of the indoor fan 4 is stopped, the heat dissipation and liquefaction of the refrigerant are hardly performed in the indoor heat exchanger 5, and the refrigerant radiates and liquefies in the outdoor heat exchanger 8, and the heat dissipation causes the outdoor heat exchange. The vessel 8 is heated to heat and melt the defrost to defrost it. The liquid refrigerant liquefied in the outdoor heat exchanger 8 is again sucked into the compressor 2 through its suction port, where the refrigerant absorbs the heat of the compressor 2 and is compressed and discharged again to the four-way valve 3. It
The compressor 2 is gradually cooled by the heat absorption of the liquid refrigerant. Hereinafter, by repeating this, the frost on the outdoor heat exchanger 8 is defrosted. Next, in S6, it is determined whether the refrigerant evaporation temperature TE exceeds a first predetermined value, for example, 5 ° C. (TE> 5),
In the case of Yes, it is determined that the defrosting is completed, and the process returns to S1 again to return to the heating operation.

However, in the case of No in S6, that is, when the refrigerant evaporation temperature TE is 5 ° C. or lower, it is judged that defrosting is still necessary, and the process returns to S3, and the refrigerant discharge temperature Td is 50 ° C.
It is determined whether or not (Td ≧ 50), and Td ≧ 50
When the above condition is satisfied, it is determined that the heat storage amount of the compressor 2 is still sufficient, and the mechatronic defrosting is continued in S4, but N
o, that is, when Td ≧ 50 is not established, it is determined that the heat storage amount of the compressor 2 is small and is cold, and the process proceeds to reverse defrosting in S5 as shown in FIG.

The reverse defrosting operation is carried out in accordance with the sequence shown in FIG. 3, and the four-way valve 3 is switched from ON to O.
It is reversed to FF, and the circulation direction of the refrigerant is reversed in the direction of the broken line arrow in FIG. Moreover, the operating frequency of the compressor 2 is reduced to, for example, 62 Hz, and the operation of the indoor and outdoor fans 4 and 7 is stopped. The opening degree of the expansion valve 6 is kept constant at substantially the same opening degree as that of the constant superheat control during the heating operation.

As a result, the high-temperature and high-pressure gaseous refrigerant from the compressor 2 is guided by the four-way valve 3 which is reversed from that during the heating operation, first flows into the outdoor heat exchanger 8 and radiates heat there. The outdoor heat exchanger 8 is liquefied by heating and the outdoor heat exchanger 8 is heated, and the frost on the outer surface of the outdoor heat exchanger 8 is heated and melted for defrosting.

Then, the liquid refrigerant liquefied in the outdoor heat exchanger 8 passes through the expansion valve 6 having a predetermined opening degree and flows into the indoor heat exchanger 5 in which the operation of the indoor fan 4 is stopped. After absorbing heat by convection and evaporating, it is guided by the four-way valve 3 and returned to the compressor 2 from the suction port again. Therefore, it is possible to reduce the amount of liquid back that the liquid refrigerant is returned to the compressor 2, so that the reliability of the compressor 2 can be improved. Since the outdoor heat exchanger 8 is heated and the frost is defrosted by repeating the above, in the next S7, it is repeatedly determined whether the evaporation temperature TE is higher than 5 ° C. (TE> 5), When TE> 5 is satisfied, it is determined that the defrosting is completed, the process returns to S1, the heating operation is resumed, and the following steps are repeated.

Therefore, according to this embodiment, the refrigerant discharge temperature detection value Td detected by the discharge temperature sensor 11 is obtained.
The temperature of the compressor 2, that is, the heat storage amount is detected based on the above, and when the heat storage amount is sufficient, the mechatronics defrosting operation of defrosting by the heat storage of the compressor 2 is performed, so that the indoor heat exchanger 5 is cooled. It is possible to defrost while keeping it in a high temperature state without performing it. Therefore, the temperature of the warm air heated by the indoor heat exchanger 5 can be speeded up when the heating operation is returned. In other words, it is possible to speed up the start-up of heating restoration and improve comfort.

Further, when the heat storage amount of the compressor 2 is gradually reduced by the mechatronic defrosting and the discharge temperature is reduced to, for example, 50 ° C. or less, it is judged that the supply heat source for the defrosting is exhausted, and the reverse defrosting operation is started. However, in this reverse defrosting, the refrigerant absorbs heat in the indoor heat exchanger 5, so the heat source for defrosting is not exhausted. Further, since the amount of liquid back to the compressor 2 is small, troubles and the like of the compressor 2 due to liquid back can be prevented and reliability can be improved.

FIG. 4 is a refrigerating cycle diagram of the second embodiment of the present invention. This air conditioner 21 has a compressor 2 with respect to the refrigerating cycle of the air conditioner 1 as an outdoor heat exchanger. Quick defrosting is possible by providing a bypass passage 22 communicating with the refrigerant passage connecting the exchanger 8 and the expansion valve 6 and a capillary tube 23 and a two-way valve 24 interposed in the bypass passage 22 respectively. And the point that the outdoor controller 12A is configured to freely switch between quick defrosting and reverse defrosting during heating operation based on the discharge temperature.

That is, the outdoor controller 12A operates the quick defrosting based on the discharge temperature Td during the heating operation according to the second control program shown in FIG. 5, for example, or from the quick defrosting to the reverse defrosting. The control for shifting is performed.

That is, the second embodiment is the first embodiment shown in FIG.
The S4 mechatronic defrost in the control program of FIG. 6 is replaced with the quick defrost of S14 in the second control program shown in FIG. 5, and the mechatronic defrost in the sequence shown in FIG. It is characterized in that it is replaced with quick defrost Quick defrost is a part of the high-temperature high-pressure gaseous refrigerant discharged from the compressor 2 by opening the two-way valve 24 shown in FIG. 4 during the heating operation. Is introduced into the outdoor heat exchanger 8 through the bypass passage 22 to radiate heat and liquefy, and the radiated heat heats and melts the frost on the outdoor heat exchanger 8 to defrost it. Then, the liquid refrigerant liquefied in the outdoor heat exchanger 8 is guided by the four-way valve 3 which is on and sucked into the compressor 2, where it absorbs the heat stored in the compressor 2 and is compressed again and discharged.

Therefore, the quick defrost is similar to the mechatronic defrost in that the heat of the compressor 2 is used as a heat source for the defrost, and the indoor heat exchanger 5 can be kept at a high temperature without being cooled, and the effect is almost the same. The effect can be obtained. , That is, compressor 2
When the discharge temperature Td of is equal to or higher than 50 ° C. (Td ≧ 50), it is determined that the heat storage of the compressor 2 has a sufficient amount of heat necessary for defrosting, and quick defrosting is performed, or the discharge temperature Td is 5
When the temperature is 0 ° C. or lower, reverse defrosting is performed, so that the same effect as the second embodiment is obtained.

In each of the above embodiments, the discharge temperature sensor 11 is provided and the defrosting operation is controlled according to the heat storage amount of the compressor 2 in accordance with the refrigerant discharge temperature Td. However, the present invention has this discharge temperature Td. Instead of this, the case temperature or the degree of dilution of the compressor 2 or ΔT, which is the difference between the case temperature of the compressor 2 and the saturation temperature of the high-pressure reference, may be used.

FIG. 7 is a flow chart of a control program according to the third embodiment of the present invention. This is performed by the outdoor controller 12 or 12A for storing heat in the compressor 2 as in the case of mechatronic defrosting shown in the sequence diagram of FIG. In the case of defrosting based on the temperature of the compressor 2 that contains lubricating oil, the defrosting operation is terminated in accordance with the case temperature of the compressor 2 (hereinafter referred to as the comp case temperature) or the change of the comp case temperature. Is characterized in that it is returned to the heating operation in a state in which is always kept above a predetermined value.

Here, the Compcase temperature will be described as an example, but the Compcase temperature is proportional to the discharge temperature, and the discharge temperature may be detected instead of the Compcase temperature and the following control may be performed. Further, the degree of dilution of the refrigerant or ΔT may be used, and the same effect can be obtained by these.

Next, the outdoor controller 12 or 12A
The control program will be described with reference to the flowchart of FIG. In FIG. 7, S21 to S28 indicate steps of the flowchart.

First, when the heating operation is started in S21, it is repeatedly judged in the next S22 whether or not the state in which the refrigerant evaporation temperature TE of the outdoor heat exchanger 8 is, for example, −2 ° C. or lower has continued for 30 minutes, and Yes. When it is determined that defrosting is necessary, S
The defrosting operation is started at 23. This defrosting operation is, for example, the case of defrosting by storing heat of the compressor 2 such as mechatronic defrosting shown in FIG. 8, so that the comp case temperature Tk gradually decreases as defrosting progresses.

When the Compcase temperature Tk decreases and the difference ΔT (see FIG. 9) between the Compcase temperature Tk and the high temperature standard saturation temperature of the refrigerant approaches zero, the liquid refrigerant condenses in the compressor 2. As a result, the viscosity of the lubricating oil is reduced. Further, when a larger amount of liquid refrigerant is condensed, a liquid discharge phenomenon occurs in which the condensed liquid refrigerant and lubricating oil are discharged from the compressor 2, and the reliability of the compressor 2 is reduced.

Therefore, in the next step S24, the Compcase temperature Tk is a first predetermined value, for example, 50 ° C. or lower (Tk <
50), and if Yes, the defrosting is ended in S25 and the heating operation is resumed. As a result, it is possible to prevent the Comp case temperature Tk from lowering to 50 ° C. or less and the liquid ejection phenomenon to occur, thereby improving the reliability.

After the heating operation is returned, the state in which the refrigerant evaporation temperature TE is lower than -2 ° C. (TE <-2) is again 2 in S26.
It is determined whether or not 0 minute has continued, and if Yes, it is determined that defrosting is necessary again, and the defrosting of S23 is started again. There is no residual frost because the period of defrosting is accelerated.

On the other hand, when S24 is No, that is, when the Compcase temperature Tk is lower than the second predetermined value of 50 ° C., the Compcase temperature Tk is set to the minimum Compcase temperature (Tkmin) of, for example, 2 deg in S27. Is higher than the second predetermined value Tkmin + 2 which is the second predetermined value (T
k> Tkmin + 2), and if Yes, S2
At 5 the defrosting is terminated and the heating operation is resumed. As a result, liquid ejection can be prevented in advance. That is, if liquid compression continues, the discharge pressure rises, and the discharge temperature and the Compcase temperature rise accordingly. Therefore, when the Compcase temperature changes from a decrease to an increase, liquid discharge has begun to occur. become. Therefore, the liquid discharge can be prevented by ending the defrosting when the Compcase temperature starts to rise.

However, in the case of No in S27, that is, in the case where the Compcase temperature does not rise, it is judged in S28 whether or not the refrigerant evaporation temperature TE is 5 ° C. or higher. If it is Yes in S28, it is determined that the defrosting is completed, and the process returns to S21 to return to the heating operation again.

Therefore, according to the present embodiment, since the Compcase temperature Tk can be maintained at a predetermined value or more during defrosting, ΔT can be always secured during the defrosting operation as shown in FIG. As a result, it is possible to prevent deterioration of the lubricating performance of the lubricating oil and discharge of the liquid due to the decrease of ΔT, so that the reliability of the compressor 2 can be improved.

Instead of the Compcase temperature, the discharge temperature of the refrigerant, the degree of dilution, or ΔT may be used, and the same effect can be obtained.

[0051]

As described above, in the inventions of claims 1 to 5, when the discharge temperature detected by the discharge temperature sensor, the compressor case temperature, the dilution degree, Δt, etc. are high, the heat storage amount of the compressor is high. Since the compressor is at a high temperature in many cases, the control unit operates the mechatronics defrosting for defrosting or the quick defrosting for defrosting based on the heat storage amount of the compressor. Thus, the high-temperature and high-pressure gaseous refrigerant that has absorbed the heat accumulated in the compressor can be introduced into the outdoor heat exchanger through the indoor heat exchanger to defrost the frost. Moreover, since defrosting is performed while the temperature of the indoor heat exchanger remains high, startup can be accelerated when heating operation is restarted, and comfort can be improved.

When the compressor is gradually cooled by the operation of the mechatronic defrosting or the quick defrosting, and the heat storage amount is gradually reduced to lower the refrigerant discharge temperature of the compressor, the four-way valve is turned off by the control means. Is reversed to switch to reverse defrosting operation. As a result, the high-temperature and high-pressure gaseous refrigerant from the compressor is introduced into the outdoor heat exchanger to radiate heat and defrost. The liquid refrigerant that radiates heat and liquefies in the outdoor heat exchanger evaporates and absorbs heat in the indoor heat exchanger and is returned to the compressor in a gas state. Therefore, since the refrigerant absorbs heat in the indoor heat exchanger,
A shortage of the supply heat source for defrosting does not occur, and the refrigerant is returned to the compressor in a gas state, so the amount of liquid back is small. For this reason, there are few problems with the compressor,
The reliability can be improved.

According to the third aspect of the invention, the amount of heat stored in the compressor is reduced by the liquid back due to the mechatronics or quick defrosting operation, the temperature of the compressor is gradually lowered, and the compressor detected by the discharge temperature sensor is used. The first refrigerant discharge temperature is
When the temperature falls below a predetermined value of, the defrosting operation is forcibly terminated and the heating operation is restored.

As a result, the temperature of the compressor can be constantly maintained at or above the first predetermined value, so that ΔT, which is the difference between the compressor case temperature and the saturation temperature of the high-pressure reference, can be always ensured during defrosting. Therefore, it is possible to effectively prevent the deterioration of the lubricating performance of the lubricating oil in the compressor due to the decrease of ΔT and the liquid discharge of discharging the gas-liquid two-phase refrigerant mixed with the lubricating oil. The reliability can be improved.

According to the fourth aspect of the present invention, by the mechatronics or quick defrosting operation, the heat storage amount of the compressor is gradually reduced by the liquid back and the temperature of the compressor is gradually lowered, and then the discharge temperature is stored. When the predetermined temperature rises above the minimum discharge temperature during the defrosting operation, the control means forcibly terminates the defrosting operation and returns to the heating operation. Therefore, also in the present invention, since the temperature of the compressor can be always kept constant as in the case of the third aspect of the invention, each inconvenience caused by the decrease in ΔT is effectively prevented and the reliability is improved. be able to.

[Brief description of drawings]

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

FIG. 2 is a flowchart of a control program of the outdoor controller shown in FIG.

FIG. 3 is a sequence diagram of control for shifting from mechatronic defrosting to reverse defrosting by the outdoor controller shown in FIG. 1.

FIG. 4 is a refrigeration cycle diagram of a second embodiment of the present invention.

5 is a flowchart of a control program of the outdoor controller shown in FIG.

6 is a sequence diagram of control for shifting from quick defrost to reverse defrost by the outdoor controller shown in FIG.

FIG. 7 is a flowchart of a control program according to the third embodiment of the present invention.

FIG. 8 is a sequence diagram of the defrosting operation shown in FIG. 7.

9 is a graph showing that ΔT of the compressor can be constantly secured during defrosting by the defrosting operation shown in FIG. 7.

[Explanation of symbols] 1,21 Air conditioner 2 Compressor 3 Four-way valve 4 Indoor fan 5 Indoor heat exchanger 6 Expansion valve 7 Outdoor fan 8 Outdoor heat exchanger 9 Refrigerant piping 10 Evaporation temperature sensor 11 Discharge temperature sensor 12, 12A Outdoor controller 22 Bypass passage 24 Two-way valve

Claims (5)

[Claims] 1. An air conditioner having a refrigeration cycle in which at least a compressor, a four-way valve, an indoor heat exchanger equipped with an indoor fan, an expansion valve, and an outdoor heat exchanger equipped with an outdoor fan are sequentially connected by a refrigerant pipe. In the discharge temperature temperature sensor for detecting the discharge temperature of the refrigerant discharged from the compressor, the refrigerant circulating in the refrigeration cycle has the same circulation direction as in the heating operation and the expansion valve is opened, and ，
While operating either mechatronic defrosting, which stops the operation of the outdoor fan, or quick defrosting, which introduces part of the refrigerant discharged from the compressor into the outdoor heat exchanger during heating operation. According to the discharge temperature detected by the discharge temperature sensor, the circulation direction of the refrigerant circulating in the refrigeration cycle from one defrosting operation is opposite to that in the heating operation, and the operation of the indoor and outdoor fans is stopped. An air conditioner comprising: a control unit that shifts to reverse defrosting operation. 2. The air conditioner according to claim 1, wherein the control means shifts from the mechatronics defrosting or quick defrosting operation to the reverse defrosting operation when the detected value of the discharge temperature is higher than a predetermined value. An air conditioner having a configuration. 3. The air conditioner according to claim 2, wherein the control means is configured to return to the heating operation when the discharge temperature detected during the defrosting operation falls below a first predetermined value. A characteristic air conditioner. 4. The air conditioner according to claim 2 or 3, wherein the control means, when the discharge temperature detected during the defrosting operation rises by a predetermined value from the stored minimum discharge temperature during the defrosting operation. An air conditioner characterized by being configured to return to heating operation. 5. The air conditioner according to any one of claims 1 to 4, wherein the control means replaces the discharge temperature with a CompCase temperature which is a case temperature of the compressor, a dilution degree, and the CompCase. An air conditioner characterized by being configured to use either of the difference between the temperature and the saturation temperature of the high pressure standard of the refrigerant as a judgment standard.