JP7392567B2 - air conditioner - Google Patents

Description

The present invention relates to an air conditioner capable of dehumidifying operation.

Some air conditioners perform reheating and dehumidification during the cooling cycle. For example, indoor heat exchangers are divided into heat exchangers that function as condensers and heat exchangers that function as evaporators; the former heats the indoor air, while the latter dehumidifies and cools the indoor air. Ru. Here, the heat exchanger that functions as a condenser is located on the upstream side of the refrigerant flow path, and the heat exchanger that functions as an evaporator is located on the downstream side of the refrigerant flow path. Further, a pressure reducing device is provided between the upstream heat exchanger and the downstream heat exchanger.

However, if the indoor temperature is higher than the outdoor heat exchanger, evaporation of the refrigerant is likely to occur in the upstream heat exchanger, and the gas component of the refrigerant may increase before the pressure reduction device. . In such cases, the refrigerant before the pressure reduction device becomes a highly dry gas-liquid mixed refrigerant, and the pressure loss of the refrigerant in the pressure reduction device increases, making it difficult for the refrigerant to return from the indoor heat exchanger to the compressor, resulting in so-called poor circulation. may fall into. Even if the dehumidifying operation is continued when such a state occurs, the refrigerant does not circulate through the cooling flow path, so the state in which dehumidification cannot be performed continues.

In order to avoid such poor circulation to the extent that dehumidification is not possible, there is a technique for stopping the operation of the compressor based on the compressor input current that fluctuates due to poor circulation (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2000-257984

However, the compressor input current value may vary due to factors other than poor circulation, such as normal control operations to maintain temperature or humidity set by the user. Therefore, in order to accurately detect poor circulation, it is necessary to make a judgment based on a combination of other judgment criteria in addition to the input current value, making it impossible to detect poor circulation quickly and with high precision.

In view of the above circumstances, an object of the present invention is to provide an air conditioner that can quickly and accurately detect poor circulation during reheat dehumidification.

In order to achieve the above object, an air conditioner according to one embodiment of the present invention includes an indoor unit, an outdoor unit, and a control device.
The indoor unit includes: an indoor heat exchanger having a first heat exchange section and a second heat exchange section; a pressure reducing device connected between the first heat exchange section and the second heat exchange section; and a first temperature sensor that detects the temperature of the air.
The outdoor unit includes an outdoor heat exchanger, a compressor connected between the outdoor heat exchanger and the indoor unit, and a second temperature sensor that detects the temperature of the outdoor heat exchanger.
The control device is configured to control the temperature of the outdoor heat exchanger detected by the second temperature sensor during a reheat dehumidification operation in which the first heat exchange section functions as a condenser and the second heat exchange section functions as an evaporator. When it is determined that the temperature of the indoor air detected by the first temperature sensor is higher than the temperature of the indoor air, the operation of the compressor is stopped.

In such an air conditioner, the control device determines that the temperature of the indoor air detected by the first temperature sensor is higher than the temperature of the outdoor heat exchanger detected by the second temperature sensor during reheat dehumidification operation. If this happens, there is a high probability of poor circulation, so by detecting the temperature of the outdoor heat exchanger detected by the second temperature sensor and the temperature of the indoor air detected by the first temperature sensor, reheat dehumidification operation is started. This makes it possible to detect poor circulation quickly and with high precision.

In the above air conditioner, the control device includes a first control section provided in the indoor unit and a second control section provided in the outdoor unit, and stops the operation of the compressor. The second control section controls the opening degree of the pressure reducing device when the second control section receives information from the second control section that the second control section has stopped the compressor. Control may be performed to increase the amount within a predetermined time.

In such an air conditioner, the second control section provided in the outdoor unit controls the operation of the compressor to stop, and the first control section controls the second control section to stop the compressor. When receiving the information from the second control unit, the opening degree of the pressure reducing device is controlled to be increased within a predetermined period of time, so that the processing in the control unit can be distributed.

As described above, according to the present invention, there is provided an air conditioner that can quickly and accurately detect poor circulation during reheat dehumidification.

FIG. 1 is a block configuration diagram showing an overview of an air conditioner according to the present embodiment. FIG. 2 is a block diagram illustrating the respective controls of the first control section and the second control section and the electrical communication between the first control section and the second control section. It is a flow chart showing an example of control of reheat dehumidification operation of this embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In each drawing, XYZ axis coordinates may be introduced. In addition, the same members or members having the same function may be given the same reference numerals, and the description may be omitted as appropriate after the member has been described. Further, the numerical values shown below are just examples, and are not limited to these examples.

FIG. 1 is a block configuration diagram showing an overview of an air conditioner according to this embodiment. The configuration shown in FIG. 1 is an example of the air conditioner of this embodiment, and is not limited to this example. Note that "connection" in the following refers to the state in which the heat exchanger and pressure reducing device, which are parts of the refrigerant circuit, are connected through the pipe (refrigerant piping) shown by the solid line in Figure 1, and a refrigerant flow path is formed. means.

The air conditioner 1 includes an indoor unit 10, an outdoor unit 30, and a control device 40. The air conditioner 1 is an air conditioner that is capable of heating operation in addition to cooling operation and reheat dehumidification operation.

The indoor unit 10 includes an indoor heat exchanger 100, a pressure reducing device 130, a first temperature sensor 140, and an indoor fan 150. Indoor heat exchanger 100 has a first heat exchange section 110 and a second heat exchange section 120. Each of the first heat exchange section 110 and the second heat exchange section 120 includes, for example, a plurality of metal fins. In FIG. 1, the indoor fan 150 is schematically installed near each of the first heat exchange section 110 and the second heat exchange section 120, but only one indoor fan 150 may be provided.

The pressure reducing device 130 is, for example, an electromagnetic expansion valve (electromagnetic valve) whose opening degree can be adjusted. The pressure reducing device 130 is connected between the first heat exchange section 110 and the second heat exchange section 120. The first heat exchange section 110, the pressure reducing device 130, and the second heat exchange section 120 are connected in series.

The first heat exchange section 110 is connected to the pressure reduction device 330 of the outdoor unit 30 on the opposite side from the pressure reduction device 130. The second heat exchange section 120 is connected to the four-way valve 320 of the outdoor unit 30 on the opposite side from the pressure reducing device 130. Indoor fan 150 is arranged near each of first heat exchange section 110 and second heat exchange section 120.

The first temperature sensor 140 detects the temperature of indoor air to which the indoor unit 10 is attached. Examples of the first temperature sensor 140 include a thermocouple, a thermistor, and the like. The first temperature sensor 140 is not limited to being installed in the indoor unit 10, but may be installed in a remote controller that enables turning on/off the air conditioner 1, setting the temperature, etc. In this case, it is assumed that the remote controller is included in the indoor unit 10.

The outdoor unit 30 includes an outdoor heat exchanger 300, a compressor 310, a four-way valve 320, a pressure reducing device 330, a second temperature sensor 340, and an outdoor fan 350. The outdoor heat exchanger 300 includes, for example, a plurality of metal fins. The pressure reducing device 330 is, for example, an expansion valve.

Compressor 310 is connected between second heat exchange section 120 and outdoor heat exchanger 300. However, a four-way valve 320 is connected between the second heat exchange section 120 and the compressor 310 and between the outdoor heat exchanger 300 and the compressor 310.

Outdoor heat exchanger 300 is connected between four-way valve 320 and pressure reducing device 330. The pressure reducing device 330 is connected between the outdoor heat exchanger 300 and the first heat exchange section 110. The four-way valve 320, the outdoor heat exchanger 300, and the pressure reducing device 330 are connected in series. Outdoor fan 350 is arranged near outdoor heat exchanger 300.

The second temperature sensor 340 detects the temperature of the outdoor heat exchanger 300. For example, during cooling operation or reheat dehumidification operation, second temperature sensor 340 detects the temperature at the outlet of outdoor heat exchanger 300. The temperature at the outlet of the outdoor heat exchanger 300 corresponds to the temperature of the refrigerant flowing out from the outdoor heat exchanger 300 after heat exchange is performed by the outdoor heat exchanger 300. Examples of the second temperature sensor 340 include a thermocouple, a thermistor, and the like.

The control device 40 controls the indoor unit 10 and the outdoor unit 30. The control device 40 includes a first control section 41 provided in the indoor unit 10 and a second control section 42 provided in the outdoor unit 30. In the air conditioner 1, wired or wireless electrical communication (for example, serial communication, etc.) is performed between the first control section 41 and the second control section 42. Note that the control device 40 including the first control section 41 and the second control section 42 may be installed in either the indoor unit 10 or the outdoor unit 30.

For example, FIG. 2 is a block diagram showing the respective controls of the first control section and the second control section, as well as the first control section and the second control section.

The first control unit 41 controls, for example, the pressure reducing device 130, the indoor fan 150, and the like. The temperature of the indoor air detected by the first temperature sensor 140 is transmitted to the first control unit 41 . The indoor air temperature received by the first control unit 41 is transmitted to the second control unit 42 . Further, the first control unit 41 controls switching between the cooling operation and the reheat dehumidification operation of the air conditioner 1 according to the difference between the temperature detected by the first temperature sensor 140 and the set temperature set by the user. conduct. For example, if the temperature detected by the first temperature sensor 140 is higher than the set temperature, the reheating and dehumidifying operation is switched to the cooling operation.

The second control unit 42 controls, for example, the compressor 310, the pressure reducing device 330, the outdoor fan 350, and the like. The temperature at the outlet of the outdoor heat exchanger 300 detected by the second temperature sensor 340 is transmitted to the second control unit 42 . The second control unit 42 can stop the compressor 310 according to the temperatures detected by the first temperature sensor 140 and the second temperature sensor 340. This control will be described later. Further, information that the second control unit 42 has stopped the compressor 310 is transmitted to the first control unit 41 .

For example, in the reheat dehumidification operation, the first heat exchange section 110 functions as a condenser, and the second heat exchange section 120 functions as an evaporator. On the other hand, in the cooling operation, each of the first heat exchange section 110 and the second heat exchange section 120 functions as an evaporator. Since the flow of refrigerant in the reheat dehumidification operation is performed in the same direction as the cooling cycle, the operation of the cooling operation will be explained before explaining the operation of the reheat dehumidification operation.

(Cooling operation)

The flow of refrigerant during cooling operation is shown by solid arrows in FIG. First, when the compressor 310 is driven, high-pressure refrigerant flowing out from the compressor 310 flows into the four-way valve 320, and then flows into the outdoor heat exchanger 300 via the four-way valve 320. The refrigerant that has flowed into the outdoor heat exchanger 300 exchanges heat with the outside air taken in by the outdoor fan 350 and is condensed. The refrigerant flowing out from the outdoor heat exchanger 300 is decompressed when passing through the decompression device 330 whose opening degree corresponds to the cooling operation.

Next, the refrigerant flowing out from the pressure reducing device 330 flows into the first heat exchange section 110, passes through the pressure reducing device 130, which is fully opened during cooling operation, and flows into the second heat exchange section 120. . In each of the first heat exchange section 110 and the second heat exchange section 120, the refrigerant exchanges heat with the indoor air taken in by the indoor fan 150 and evaporates. As a result, cooled indoor air is discharged from the indoor unit 10.

Thereafter, the refrigerant flowing out from the second heat exchange section 120 is sucked into the compressor 310 again via the four-way valve 320 and is compressed.

(Reheat dehumidification operation)

In reheat dehumidification operation, the flow direction of the refrigerant is the same as in cooling operation. However, in the reheat dehumidification operation, the pressure reducing device 330 is fully opened, and the pressure reducing device 130 has an opening degree corresponding to the reheat dehumidification operation. Thereby, the first heat exchange section 110 functions as a condenser together with the outdoor heat exchanger 300, and the second heat exchange section 120 functions as an evaporator.

For example, the refrigerant that has undergone heat exchange with the outside air in the outdoor heat exchanger 300 passes through the pressure reducing device 330 that is fully open, and flows into the first heat exchange section 110. The refrigerant that has flowed into the first heat exchange section 110 exchanges heat with the indoor air taken in by the indoor fan 150 and is condensed. Thereafter, the refrigerant flows out from the first heat exchange section 110, passes through the pressure reducing device 130 that is opened to a predetermined degree, and is depressurized. The refrigerant then flows into the second heat exchange section 120, exchanges heat with the indoor air taken in by the indoor fan 150, and evaporates.

In the reheat dehumidification operation, the outdoor heat exchanger 300 and the first heat exchange section 110 function as a condenser, and the second heat exchange section 120 functions as an evaporator. That is, the indoor air is heated in the first heat exchange section 110, and the indoor air is dehumidified and cooled in the second heat exchange section 120.

While the reheat dehumidification operation is operating normally, the temperature at the outlet of the outdoor heat exchanger 300 (the temperature of the refrigerant at the outlet) is generally higher than the temperature of the indoor air. By flowing the refrigerant at a temperature higher than that of the indoor air into the first heat exchange section 110 and exchanging heat with the indoor air, in the reheating and dehumidifying operation, an extreme temperature drop in the indoor air is suppressed, and the temperature of the indoor air is reduced. Dehumidification can be achieved.

Note that during heating operation, the direction in which the refrigerant flows is opposite to that of cooling operation (or reheat dehumidification operation). That is, the refrigerant flows in the direction opposite to the solid arrow, the outdoor heat exchanger 300 functions as an evaporator, and the first heat exchange section 110 and the second heat exchange section 120 function as a condenser. The flow of refrigerant in and out of the four-way valve 320 during heating operation is indicated by broken line arrows in the figure.

Before explaining the operation of the air conditioner 1 of this embodiment, a phenomenon that may occur in the air conditioner during reheat dehumidification operation will be explained.

For example, when a strong wind, gust of wind, etc. flows into the outdoor unit 30 during reheat dehumidification operation, heat exchange in the outdoor heat exchanger 300 is excessive, and the refrigerant in the outdoor heat exchanger 300 is rapidly cooled. There are cases. As a result, the temperature of the indoor air may become higher than the temperature at the outlet of the outdoor heat exchanger 300.

In such a case, even in the reheat dehumidification operation mode, the first heat exchange section 110 absorbs heat from the indoor air, and the first heat exchange section 110 no longer functions as a condenser. For example, during reheat dehumidification operation, the first heat exchange section 110 temporarily acts as an evaporator.

As a result, the ratio of gas increases in the first heat exchange section 110, and the gas ratio increases in the first heat exchange section 110 corresponding to the upstream side of the pressure reduction device 130 or between the first heat exchange section 110 and the pressure reduction device 130. A highly dry two-phase refrigerant (a refrigerant in which a gas phase and a liquid phase are mixed) stagnates in the pipe between them (the part indicated by A in FIG. 1). Here, dryness means the ratio of the amount of steam (gas refrigerant) in wet steam (two-phase refrigerant). That is, it means that the higher the dryness of the two-phase refrigerant, the higher the proportion of the gas phase in the two-phase refrigerant.

When such a highly dry two-phase refrigerant is formed upstream of the pressure reducing device 130, the pressure reducing device 130, which is adjusted to a predetermined opening degree during reheat dehumidification operation, becomes a flow path with high resistance for the refrigerant, and the refrigerant becomes difficult to pass through the pressure reducing device 130.

As a result, the amount of refrigerant flowing downstream of the pressure reducing device 130 decreases, and the amount of refrigerant flowing into the second heat exchange section 120 and the amount of refrigerant flowing back to the compressor 310 decrease. As a result, the compressor 310 continues to operate with little refrigerant in the compressor 310, a state similar to so-called dry operation of the compressor, and it is difficult for the compressor 310 to push refrigerant to the outdoor heat exchanger 300 side. This leads to poor circulation.

Furthermore, even if the air conditioner is operated in such a state of poor circulation, the second heat exchange section 120 cannot sufficiently function as an evaporator due to the small amount of refrigerant in the second heat exchange section 120. Otherwise, sufficient dehumidification will not be possible at the set temperature. That is, even if the user selects the dehumidification mode, dehumidification will not be performed.

In particular, this phenomenon may occur during the initial operation of the air conditioner 1 when dehumidification (reheat dehumidification) is selected by the user and the compressor 310 is not sufficiently warmed. This is because the compressor 310 itself cannot supply warm refrigerant from the compressor 310 to the outdoor heat exchanger 300 because the compressor 310 is cold.

Further, driving the compressor 310 without refrigerant being returned to the compressor 310 places a load on the compressor 310. For example, the main body of the compressor 310, the motor that drives the compressor 310, etc. may fail.

In order to avoid such poor circulation, the air conditioner 1 of this embodiment performs the control shown in FIG. 3.

FIG. 3 is a flow diagram showing an example of control of the reheat dehumidification operation of this embodiment. The left side of FIG. 3 shows the flow of control in the indoor unit 10, and the right side shows the flow of control in the outdoor unit 30. The flow shown in FIG. 3 is automatically performed by the control device 40. For example, the indoor unit 10 is controlled by the first control unit 41, and the outdoor unit 30 is controlled by the second control unit 42.

For example, when a user selects the reheat dehumidification operation mode of the air conditioner 1 using a remote controller located indoors, the remote controller issues an instruction for reheat dehumidification operation to the first control unit 41 of the indoor unit 10 ( Step S10). Thereby, the reheating and dehumidifying operation of the air conditioner 1 is started (step S11).

When the reheat dehumidification operation is started, in the outdoor unit 30, the second control section 42 starts the operation of the outdoor unit 30. For example, the second control unit 42 starts driving the compressor 310 and starts rotating the outdoor fan 350 (step S30).

On the other hand, in the indoor unit 10, when the compressor 310 is driven for a predetermined period of time, the pressure difference of the refrigerant between the upstream side and the downstream side of the pressure reducing device 130 (electromagnetic valve) becomes a predetermined pressure difference. When this predetermined pressure difference is reached, the opening degree of the pressure reducing device 130 is adjusted to a predetermined opening degree by the first control section 41 (step S12). The predetermined opening degree of the pressure reducing device 130 is an opening degree such that the first heat exchange section 110 serves as a condenser and the second heat exchange section 120 serves as an evaporator. Note that the pressure difference between the refrigerant on the upstream side and the downstream side of the pressure reducing device 130 may be detected using a pressure sensor.

After that, the indoor unit 10 transmits the temperature (indoor temperature) detected by the first temperature sensor 140 to the second control unit 42 of the outdoor unit 30 (step S13). That is, before determining whether the temperature detected by each of the first temperature sensor 140 and the second temperature sensor 340 is high or low, the first control unit 41 of the indoor unit 10 sends the first control unit 42 to the second control unit 42 of the outdoor unit 30. The temperature of the indoor air detected by the temperature sensor 140 is transmitted.

On the other hand, the outdoor unit 30 performs a warm-up operation to warm up the compressor in order to stabilize the refrigerant pressure within the refrigeration cycle. For example, the operation of the refrigeration cycle is continued by a warm-up operation for a predetermined warm-up time (for example, several tens of minutes) (step S31). This prevents repeated restarts due to false detection of poor circulation. Note that in order to detect whether the compressor 310 has sufficiently warmed up, the temperature of the drive motor of the compressor 310 may be detected.

Next, in the outdoor unit 30, it is determined whether the indoor temperature is higher than the temperature of the outdoor heat exchanger 300 (step S32). For example, it is determined whether "the temperature detected by the second temperature sensor 340<the temperature detected by the first temperature sensor 140".

Here, if the temperature of the outdoor heat exchanger 300≧the indoor temperature (step S32-NO), it is subsequently determined whether the indoor temperature is higher than the temperature of the outdoor heat exchanger 300. On the other hand, if the temperature of the outdoor heat exchanger 300<the indoor temperature (step S32-YES), the compressor 310 is stopped (step S33). Further, information that the compressor 310 has stopped is transmitted from the second control section 42 to the first control section 41.

Next, the first control unit 41 of the indoor unit 10 determines whether the compressor 310 is stopped based on the information transmitted from the compressor 310 (step S14). Here, if the compressor 310 is not stopped (step S14-NO), the first control unit 41 continues to determine whether the compressor 310 is stopped.

On the other hand, if the first control unit 41 determines that the compressor 310 is stopped (S14-YES), the first control unit 41 controls the pressure reducing device 130 (electromagnetic (valve) fully open.

In this way, the second control unit 42 controls the operation of the compressor 310 to be stopped. Further, when the first control unit 41 receives information from the second control unit 42 that the second control unit 42 has stopped the compressor 310, the first control unit 41 adjusts the opening degree of the pressure reducing device 130 during the reheat dehumidification operation within a predetermined time. Control is performed to increase the opening degree more than the opening degree.

This eliminates poor circulation in which the pressure loss of the refrigerant in the pressure reduction device 130 becomes large and makes it difficult for the refrigerant to return from the indoor heat exchanger 100 to the compressor 310. The high-pressure refrigerant on the side flows downstream of the pressure reducing device 130, and it is possible to equalize the pressure of the refrigerant on the upstream and downstream sides of the pressure reducing device 130. In other words, the amount of refrigerant flowing downstream from the pressure reducing device 130 increases, the amount of refrigerant flowing into the second heat exchange section 120, and the amount of refrigerant flowing back to the compressor 310 increases.

As a result, even if the reheat dehumidification operation is restarted (step S11), there is a sufficient amount of refrigerant in the compressor 310, so the compressor 310 is unlikely to run dry, and the compressor 310 The refrigerant can be pushed out to the outdoor heat exchanger 300 side. In other words, dry operation of the compressor in which the compressor 310 operates with little refrigerant in the compressor 310 is avoided, and poor circulation such as the compressor 310 being unable to push refrigerant to the outdoor heat exchanger 300 side is avoided. Avoided.

At this time, the compressor 310 is sufficiently warm and can supply high-pressure, high-temperature refrigerant to the outdoor heat exchanger 300. As a result, the refrigerant in the outdoor heat exchanger 300 is no longer cooled rapidly, the temperature of the outdoor heat exchanger 300≧the indoor temperature is maintained, and the reheat dehumidification operation is stably continued.

As described above, in this embodiment, the second temperature sensor 340 is activated during the reheat dehumidification operation in which the control device 40 causes the first heat exchange section 110 to function as a condenser and the second heat exchange section 120 to function as an evaporator. If it is determined that the temperature of the indoor air detected by the first temperature sensor 140 is higher than the detected temperature of the outdoor heat exchanger 300, a reset operation (restart) is performed to stop the operation of the compressor 310, Reheat dehumidification operation is executed again. Note that after the reset operation, as described above, there is a sufficient amount of refrigerant in the compressor 310, so the compressor 310 can push out the refrigerant to the outdoor heat exchanger 300 side, and the reheat dehumidification is performed. Operation continues.

In particular, in this embodiment, the reset operation is applied to the compressor 310 by directly determining the difference between the temperature of the outdoor heat exchanger and the temperature of the indoor air, which is the starting point of poor circulation during reheat dehumidification operation. Therefore, it is possible to quickly and accurately detect poor circulation during reheat dehumidification operation without having to make a judgment based on a combination of other judgment criteria in addition to the input current value of the compressor.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and can be modified in various ways. Each embodiment is not necessarily an independent form, and can be combined to the extent technically possible.

1... Air conditioner 10... Indoor unit 30... Outdoor unit 40... Control device 41... First control section 42... Second control section 100... Indoor heat exchanger 110... First heat exchange section 120... Second heat exchange section 130 ...Pressure reducing device 140...First temperature sensor 150...Indoor fan 300...Outdoor heat exchanger 310...Compressor 320...Four-way valve 330...Pressure reducing device 340...Second temperature sensor 350...Outdoor fan

Claims (2)

An indoor heat exchanger having a first heat exchange part and a second heat exchange part, a pressure reducing device connected between the first heat exchange part and the second heat exchange part, and detecting the temperature of indoor air. an indoor unit having a first temperature sensor;
an outdoor unit including an outdoor heat exchanger, a compressor connected between the outdoor heat exchanger and the indoor unit, and a second temperature sensor that detects the temperature of the outdoor heat exchanger;
During a reheat dehumidification operation in which the first heat exchange section functions as a condenser and the second heat exchange section functions as an evaporator, the temperature of the outdoor heat exchanger detected by the second temperature sensor is higher than the temperature of the first heat exchanger. An air conditioner comprising: a control device that stops the operation of the compressor when it is determined that the temperature of the indoor air detected by the temperature sensor is higher. The air conditioner according to claim 1,
The control device includes a first control section provided in the indoor unit and a second control section provided in the outdoor unit,
The second control unit performs control to stop the operation of the compressor,
When the first control unit receives information from the second control unit that the second control unit has stopped the compressor, the first control unit controls the opening degree of the pressure reducing device to be increased within a predetermined time. harmonizer.

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