JPH08327193A - Air conditioner - Google Patents

Abstract

PURPOSE: To shorten a defrosting operation time and improve a comfortable feeling by a method wherein either a mechatronics defrosting operation for stopping an operation of an indoor fan and an outdoor fan or a reverse defrosting operation for stopping an operation of an indoor fan and an outdoor fan is selected and run in response to a detected defrosting load. CONSTITUTION: An outdoor heat exchanger 8 is provided with a surrounding air temperature sensor 10 and an evaporating temperature sensor 11. These both sensors 10 and 11 are connected to an outdoor controller 12. The outdoor controller 12 detects a presence or a non-presence of necessity of defrosting of the outdoor heat exchanger 8 and a defrosting load in response to a surrounding air temperature read from a surrouding air temperature sensor 10 and a refrigerant evaporating temperature read from an evaporating temperature sensor 11 in accordance with a program when a heating operation is carried out, one of the reverse defrosting operation and the mechatronics defrosting operation is selected in response to the defrosting load and operated. With such an arrangement as above, it is possible to shorten a defrosting time and improve a comfortable feeling.

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, etc. as a defrosting method for this type of air conditioner. In the reverse defrosting method, as shown in the sequence diagram of FIG. 6, the four-way valve that is on during the heating operation is reversed to be turned off, the circulation direction of the refrigerant is reversed from that during heating, and the expansion that is the flow control valve (mechatronic valve) is performed. This is an operation method in which the opening of the valve is controlled to be kept constant at a predetermined opening, and the operation of the indoor / outdoor fan is stopped.

That is, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor is introduced into the outdoor heat exchanger, where it radiates heat to be liquefied, and the radiated heat heats and melts frost on the outer surface of the outdoor heat exchanger. Can be defrosted and defrosted. Further, the liquid refrigerant liquefied in the outdoor heat exchanger flows into the indoor heat exchanger through the expansion valve, is vaporized 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.

However, in such a reverse defrosting system, the liquefied refrigerant flowing into the indoor heat exchanger evaporates and absorbs heat, so that the indoor heat exchanger is cooled. For this reason, after the reverse defrosting operation is completed, it takes several minutes until the indoor heat exchanger is heated and the heating operation is started. In other words, there is a feature that the start-up of heating operation is slow. Also,
When the amount of frost is large, the refrigerant temperature of the outdoor heat exchanger during reverse defrost gradually decreases from the gas line side (defrost inflow side) to the liquid line side (defrost outflow side) due to the melting of frost. In some cases, 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 feature that is not used for.

On the other hand, in the mechatronic defrosting method, the expansion valve is opened while the four-way valve is not turned off during the heating operation and is kept on while the indoor and outdoor fans are simply stopped. The frost of the outdoor heat exchanger is heated and melted by heat storage and its input (electric power) to defrost the heat.

Therefore, the high-temperature and high-pressure refrigerant discharged from the compressor sequentially flows into the outdoor heat exchanger through the four-way valve, the indoor heat exchanger, and the expansion valve, and the outdoor heat exchanger radiates a part of the refrigerant. Defrosting is performed by melting the frost, and on the other hand, the liquid refrigerant liquefied by the defrosting is returned again to the compressor, where it absorbs heat, is compressed again, and is discharged.
Therefore, the compressor is cooled by the liquid refrigerant sucked inside, and the temperature gradually decreases.

However, such a mechatronic defrosting method is a method of defrosting by frosting the frost of the outdoor heat exchanger by heating and frosting the frost of the outdoor heat exchanger by the heat storage amount of the compressor and the heat amount of its input (electric power). When the compressor cools down due to almost no heat storage in the frost, the liquid refrigerant accumulates in the compressor and eventually the liquid refrigerant and the lubricating oil in the compressor are discharged, which causes the liquid discharge phenomenon. It may break down.

[0009]

Since the conventional air conditioner is operated by either the reverse defrosting system or the mechatronic defrosting system regardless of the defrosting load (frosting amount), For example, since the reverse defrosting operation is performed even when the amount of frost is small and the defrosting load is relatively light, there is a problem that the rising of the heating operation is slow.

Further, since the mechatronics defrosting operation is performed even when the defrosting load is heavy, there is a problem that the compressor may be damaged due to discharge of liquid from the compressor.

Therefore, an object of the present invention is to shorten the defrosting operation time and improve comfort by selectively executing the mechatronics defrosting operation and the reverse defrosting operation according to the defrosting load. It is to provide an air conditioner that can.

[0012]

According to the first aspect of the present invention,
An air conditioner that has a refrigeration cycle that allows free cooling and heating 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 refrigerant piping to circulate a refrigerant. In the machine, a defrosting load detecting means for detecting a load necessary for defrosting the frost formed on the outdoor heat exchanger during the heating operation of the refrigeration cycle, and a defrosting load detected by the defrosting load detecting means. Accordingly, the circulation direction of the refrigerant circulating in the refrigeration cycle is the same as that in the heating operation, the expansion valve is opened, and the mechatronics defrosting operation for stopping the operation of the indoor and outdoor fans and the refrigeration cycle are performed. The reverse defrosting operation, in which the circulation direction of the circulating refrigerant is opposite to that in the heating operation and the operation of the indoor and outdoor fans is stopped, is executed. And a control means,.

According to a second aspect of the present invention, in the air conditioner according to the first aspect, the control means performs the mechatronic defrosting operation when it is determined that the defrosting load is light, and the reverse defrosting operation when it is determined that the defrosting load is heavy. It is configured to perform frost operation.

According to a third aspect of the present invention, in the air conditioner according to the second aspect, the control means is configured to reverse the four-way valve after stopping the indoor fan when performing the reverse defrosting operation.

According to a fourth aspect of the present invention, in the air conditioner according to the third aspect, the control means fully opens the expansion valve when the operation of the indoor fan is stopped, while narrowing the expansion valve to a predetermined opening after reversing the four-way valve. It is a composition.

According to a fifth aspect of the present invention, in the air conditioner according to any one of the first to fourth aspects, the defrost load detecting means is an outside air temperature sensor for detecting an outside air temperature, and an outdoor heat exchanger. Of the evaporation temperature sensor that detects the evaporation temperature of the refrigerant, the humidity sensor that detects the humidity of the air-conditioned space, the outdoor fan rotation speed detection means that detects the rotation speed of the outdoor fan, and the operation frequency detection means that detects the operation frequency of the compressor At least one of.

[0017]

According to the present invention, when the defrosting load detected by the defrosting load detecting means is light, the control means selects and executes the mechatronics defrosting operation. The defrosting operation can be performed while the temperature remains high. Further, since the defrosting load is light, the defrosting operation time can be shortened. For this reason, it is possible to speed up the start-up of the heating operation after the completion of the defrosting operation, so that it is possible to improve both comfort and heating efficiency.

On the other hand, when the defrosting load is heavy, the reverse defrosting operation is selected and executed by the control means, so that the liquid back amount of the refrigerant returned to the compressor can be reduced. For this reason, it is possible to prevent the failure of the compressor due to the liquid back, so that the reliability can be improved.

According to the third aspect of the invention, when the reverse defrosting operation is performed, the four-way valve is reversed (OF) after the indoor fan is stopped without immediately reversing (OFF) the four-way valve.
F), the high-temperature and high-pressure refrigerant accumulated in the indoor heat exchanger can be introduced into the outdoor heat exchanger through the ON four-way valve immediately after the defrosting operation is started, and can be effectively used for defrosting. The time required for defrosting can be shortened.

According to the fourth aspect of the invention, when the operation of the indoor fan is stopped by the start of the reverse defrosting operation, the expansion valve is fully opened, so that the high temperature and high pressure refrigerant accumulated in the indoor heat exchanger during the heating operation is A part of the refrigerant can be introduced into the outdoor heat exchanger from the refrigerant outlet side during the reverse defrosting operation through the expansion valve that is fully open. Therefore, the residual frost on the refrigerant outlet side end can be defrosted by heating it with a high-temperature and high-pressure gaseous refrigerant.

[0021]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5, 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 operation of the indoor fan 4 is stopped, the mechatronic defrosting operation is performed by circulating the refrigerant in the direction of the solid line arrow in the figure, and the reverse defrosting operation is performed by circulating the refrigerant in the direction of the broken line arrow in the figure.

The outdoor heat exchanger 8 has an outside air temperature sensor 10 for detecting the outside air temperature To as defrosting load detecting means.
And an evaporation temperature sensor 11 that detects the evaporation temperature TE of the refrigerant that evaporates in the outdoor heat exchanger 8, and these sensors 10 and 11 are electrically connected to an outdoor controller 12 which is a control means by a signal line. Connected to.

The outdoor controller 12 is composed of, for example, a microprocessor, and during heating operation, the outside air temperature To read from the outside air temperature sensor 10 and the refrigerant evaporation temperature TE read from the evaporation temperature sensor 11 according to the control program shown in FIG. The presence or absence of the need for defrosting of the outdoor heat exchanger 8 and the defrosting load are detected based on, and one of the reverse defrosting operation and the mechatronics defrosting operation is selected and executed based on the defrosting load. Is.

Next, a control program for the defrosting operation 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 11 in S2 is, for example, Lower than -2 ° C (TE <-
2) It is repeatedly judged whether or not the state is continued for 30 minutes, and if Yes, it is judged that defrosting is necessary, and the outside air temperature To read from the outside air temperature sensor 10 in S3 is, for example, 2 ° C. or less. It is determined whether or not (To ≦ 2). If Yes, it is determined that the defrosting load on the outdoor heat exchanger 8 is heavy, and the reverse defrosting operation of S4 is selected and executed.
In the case of o, it is determined that the defrosting load is light, and the mechatronics defrosting operation is selectively executed in S5.

The reverse defrosting operation is carried out in accordance with the sequence shown in FIG. 3. During the heating operation, the four-way valve 3 is reversed from ON to OFF at the start of the defrosting operation, and the circulation direction of the refrigerant is shown. 1 Reverse in the direction of the dashed arrow.
Further, the operating frequency of the compressor 2 is reduced to, for example, 62 Hz, and the operation of the indoor fan 4 is stopped. However, for the outdoor fan 7, a predetermined time, for example, 20
The operation is stopped after a second, and the opening degree of the expansion valve (mechatronics valve) 6 is kept constant at an opening degree substantially the same as the opening degree 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. Liquefy with. Therefore, the outdoor heat exchanger 8 can be heated by the heat radiation, and the frost on the outer surface can be heated and melted to remove the frost. Since the operation of the outdoor fan 7 is continued for about 20 seconds from the start of defrosting, the outdoor heat exchanger 8
The amount of heat exchange in is large.

Then, the liquid refrigerant liquefied in the outdoor heat exchanger 8 flows through the expansion valve 6 having a predetermined opening degree into the indoor heat exchanger 5 in which the operation of the indoor fan 4 is stopped, where it naturally flows. 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 liquid back amount of the liquid refrigerant returned to the compressor 2. By repeating this, the outdoor heat exchanger 8 is heated and the frost is defrosted. Therefore, in the next S6, it is repeatedly determined whether or not the evaporation temperature TE is higher than 5 ° C. (TE> 5), and TE When> 5 is satisfied, it is determined that the defrosting is completed, the process returns to S1 again, the heating operation is started, and the following steps are repeated again.

On the other hand, in the mechatronic defrosting of S5, even if the defrosting operation is started as shown in the sequence of FIG. 4, the four-way valve 3 is continuously turned on without being inverted from on to off. It is different from the reverse defrosting operation in that the opening of the expansion valve 6 is controlled to be fully opened or close to it.

Therefore, the circulation direction of the cooling 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 that is on, sequentially passes 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
Hereinafter, by repeating this, the frost on the outdoor heat exchanger 8 is defrosted. Next, in S7, the refrigerant evaporation temperature TE is, for example, 5 ° C.
It is repeatedly determined whether or not (TE> 5) is exceeded, and in the case of Yes, the process returns to S1 again to start the heating operation.

Therefore, according to the present embodiment, when the defrosting load on the outdoor heat exchanger 8 is heavy, the refrigerant discharged from the compressor 2 is directly guided to the outdoor heat exchanger 8 by the reverse defrosting operation, so that the outdoor heat exchanger 8 is reliably attached. Since frost is defrosted, liquid back can be reduced. Therefore, it is possible to effectively prevent the occurrence of the failure of the compressor 2 due to the liquid back, and thus the reliability can be improved.

When the defrosting load is light, defrosting is performed by the mechatronics defrosting operation. However, since the defrosting load is light, the defrosting operation time can be shortened and the refrigerant discharged from the compressor 2 can be discharged. First, since it is guided to the indoor heat exchanger 5, the temperature of the indoor heat exchanger 5 can be maintained at a high level, and the warm air blow-up can be speeded up at the start of heating operation after the completion of defrosting, thus improving comfort. You can

FIG. 5 shows another sequence when the reverse defrosting operation is performed by the outdoor controller 12.
This is because the four-way valve 3 is not turned off immediately but kept on for a predetermined time of, for example, about 30 seconds after the stop of the indoor fan 4 whose operation is stopped at the start of defrosting, and after the predetermined time has passed. It is characterized in that it is turned off and reversed, and that the opening degree of the expansion valve 6 is fully opened for a predetermined time of, for example, about 30 seconds after the operation of the indoor fan 4 is stopped, and then it is narrowed down to the predetermined opening degree.

That is, when the four-way valve 3 is turned off and reversed at almost the same time as the start of the reverse defrosting operation, the indoor heat exchanger 5
The high-temperature and high-pressure refrigerant heat accumulated inside is radiated by the refrigerant pipe 9 and the suction cup 2a and cannot be used for defrosting. Therefore, in the present embodiment, the four-way valve 3 is not turned off almost at the same time as the start of the reverse defrosting operation, and is kept in the on state for, for example, 30 seconds. The heat exchanger 8 through the four-way valve 3 in the on state and the expansion valve 6 in the fully opened state.
It can be introduced inside and used for defrosting. Therefore, the defrosting operation time can be shortened accordingly, and the comfort can be improved.

Further, in the present embodiment, since the opening degree of the expansion valve 6 is fully opened for, for example, about 30 seconds after the operation of the indoor fan 4 is stopped, the inside of the indoor heat exchanger 5 is passed through the expansion valve 6 which is being fully opened. A part of the high-temperature and high-pressure gaseous refrigerant accumulated in the above can be introduced into the outdoor heat exchanger 8 from the liquid line side (refrigerant outlet side during reverse defrosting). For this reason, the temperature of the refrigerant decreases during reverse defrosting, and as shown in FIG.
Since the residual frost on the outer surface of the end portion on the liquid line side can be heated and defrosted before the reverse defrosting is started, the residual frost 13 is not generated after the reverse defrosting is completed.

In each of the above-mentioned embodiments, the outside air temperature sensor 10 and the steam temperature sensor 1 are used as defrosting load detecting means.
1 and 2 are used in combination, the present invention, in addition to these sensors 10 and 11, a humidity sensor, an outdoor fan rotation speed detecting means for detecting the rotation speed of the outdoor fan 7, an operating frequency of the compressor 2. Any of the operating frequency detecting means for detecting the above, or an appropriate combination thereof may be used.

[0038]

As described above, in the inventions of claims 1 to 4, when the defrosting load detected by the defrosting load detecting means is light, the control means selects and executes the mechatronic defrosting operation. Therefore, the defrosting operation can be performed while the temperature of the indoor heat exchanger remains high. Also,
Since the defrosting load is light, the defrosting operation time can be shortened. For this reason, it is possible to speed up the start-up of the heating operation after the completion of the defrosting operation, so that it is possible to improve both comfort and heating efficiency.

On the other hand, when the defrosting load is heavy, the reverse defrosting operation is selected and executed by the control means, so that defrosting can be reliably performed and the liquid back amount of the refrigerant returned to the compressor is reduced. be able to. For this,
Since it is possible to prevent breakdown of the compressor due to liquid back, reliability can be improved.

In the third aspect of the present invention, when the reverse defrosting operation is performed, the four-way valve is reversed (OFF) without stopping the indoor fan without immediately reversing (OFF) the four-way valve.
F), the high-temperature and high-pressure refrigerant accumulated in the indoor heat exchanger can be introduced into the outdoor heat exchanger through the ON four-way valve immediately after the defrosting operation is started, and can be effectively used for defrosting. The time required for defrosting can be shortened.

According to the fourth aspect of the present invention, the expansion valve is fully opened when the operation of the indoor fan is stopped by the start of the reverse defrosting operation, so that the high temperature and high pressure refrigerant accumulated in the indoor heat exchanger during the heating operation is A part of the refrigerant can be introduced into the outdoor heat exchanger from the refrigerant outlet side during the reverse defrosting operation through the expansion valve that is fully open. Therefore, the residual frost on the refrigerant outlet side end can be defrosted by heating it with a high-temperature and high-pressure gaseous refrigerant.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of an 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 a reverse defrosting operation according to the embodiment shown in FIG.

FIG. 4 is a sequence diagram of a mechatronic defrosting operation according to the embodiment shown in FIG.

5 is a sequence diagram of another mechatronic defrosting operation according to the embodiment shown in FIG.

FIG. 6 is a sequence diagram of a conventional reverse defrosting operation.

[Explanation of symbols]

 1 Air Conditioner 2 Compressor 2a Suction Cup 3 Four Way Valve 4 Indoor Fan 5 Indoor Heat Exchanger 6 Expansion Valve (Flow Control Valve) 7 Outdoor Fan 8 Outdoor Heat Exchanger 9 Refrigerant Piping 10 Outside Air Temperature Sensor 11 Evaporation Temperature Sensor 12 Outdoor Controller (control means) 13 Residual frost

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F24F 11/02 101 F24F 11/02 101Q

Claims (5)

[Claims] 1. A refrigerating system capable of cooling and heating 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 to circulate a refrigerant. In an air conditioner having a cycle, a defrost load detection means for detecting a load necessary for defrosting frost formed on the outdoor heat exchanger during a heating operation of the refrigeration cycle, and the defrost load detection means In accordance with the detected defrost load, the circulation direction of the refrigerant circulating in the refrigeration cycle is the same as that during the heating operation, the expansion valve is opened, and the mechatronics defrosting operation is performed to stop the operation of the indoor and outdoor fans. , A reverse defrosting operation in which the circulation direction of the refrigerant circulating in the refrigeration cycle is opposite to that in the heating operation and the operation of the indoor and outdoor fans is stopped. An air conditioner characterized in that it has an execution allowed to control means. 2. The air conditioner according to claim 1, wherein the control means performs a mechatronics defrosting operation when it is determined that the defrosting load is light, and performs a reverse defrosting operation when it is determined that the defrosting load is heavy. An air conditioner characterized by being present. 3. The air conditioner according to claim 2, wherein the control means is configured to reverse the four-way valve after stopping the indoor fan when performing the reverse defrosting operation. . 4. The air conditioner according to claim 3, wherein the control means is configured to fully open the expansion valve when the operation of the indoor fan is stopped, and to throttle the expansion valve to a predetermined opening after reversing the four-way valve. And an air conditioner. 5. The air conditioner according to any one of claims 1 to 4, wherein the defrosting load detecting means detects an outside air temperature sensor for detecting an outside air temperature and an evaporation temperature of the refrigerant in the outdoor heat exchanger. At least one of an evaporating temperature sensor, a humidity sensor for detecting the humidity of the air-conditioned space, an outdoor fan rotation speed detecting means for detecting the rotation speed of the outdoor fan, and an operating frequency detecting means for detecting the operating frequency of the compressor. An air conditioner characterized by that.