JPH07208813A - Air conditioner - Google Patents

Abstract

PURPOSE:To provide an air conditioner in which disturbance of flow rate of refrigerant at a throating device can be prevented and stable operation can always be performed even if the operating condition is varied when the degree of opening of the throating device is controlled in response to the degree of over-heating of refrigerant within an indoor device during cooling operation. CONSTITUTION:A valve opening degree control device 11 calculates the over-heating degree of gaseous refrigerant on the refrigerant discharging side of an indoor heat exchanger B in reference to each of refrigerant temperatures detected by the second and the third temperature sensing means 9, 10 and the valve opening degree of the throating device 5 is controlled on the basis of the difference between the calculated over-heating degree and the target over-heating degree. In this case, at first, an over- cooling degree of the liquid refrigerant at the refrigerant discharging side of an outdoor heat exchanger 3 is calculated in response to the pressure and the temperature obtained from the first pressure sensing means 7 and the first temperature sensing means 8. Subsequently, when the over-cooling degree is low, the target over-heating degree is changed to be set to a larger value. With such an arrangement as above, the valve opening degree of the throating device is reduced and a high pressure side refrigerant pressure is increased, so that a sufficient high over-cooling degree can be stably assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for controlling the valve opening of a throttle device by the degree of superheat of the refrigerant on the refrigerant outlet side of an indoor heat exchanger.

[0002]

2. Description of the Related Art The prior art of this type of air conditioner will be described below. FIG. 19 is an overall configuration diagram showing a conventional air conditioner. In FIG. 19, A is a heat source unit which is an outdoor unit, B is an indoor unit, 1 is a compressor, 2 is a four-way switching valve, 3
Is an outdoor heat exchanger, 4 is an accumulator, 5 is a throttling device, 6 is an indoor heat exchanger, 9 is a second temperature detector attached to one of the connecting portions of the throttling device 5 and the indoor heat exchanger 6. Means 10 is a third temperature detecting means attached to the other connecting portion of the indoor heat exchanger 6, and 11d is a temperature detected by the second temperature detecting means 9 and the third temperature detecting means 10. The superheat degree of the gas refrigerant is obtained from the obtained superheat degree, and the obtained superheat degree is compared with a predetermined target superheat degree set in advance, and the valve opening degree of the expansion device 5 is controlled based on the deviation. It is a valve opening control means. In addition, FIG.
In, the solid arrow indicates the direction in which the refrigerant flows during the cooling operation.

In such an air conditioner, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is supplied to the four-way switching valve 2
After being sent to the outdoor heat exchanger 3 and exchanged heat with the outdoor air to be liquefied there, the pressure is reduced by the expansion device 5 and further sent to the indoor heat exchanger 6 to exchange heat with the indoor air. It gasifies and cools the room. Then, the gasified refrigerant is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4. In the case of such a cooling operation, the valve opening control means 11d
Is the second temperature detecting means 9 and the third temperature detecting means 10.
The superheat degree of the gas refrigerant on the outlet side of the indoor heat exchanger 6 is obtained from the respective temperatures detected in step S1, and based on the deviation obtained by comparing the superheat degree with a predetermined target superheat degree, The flow rate of the refrigerant is controlled by increasing or decreasing the valve opening.

[0004]

Since the conventional air conditioner is constructed as described above, for example, when the outdoor air temperature is lowered, the refrigerant pressure on the high pressure side is largely reduced, and the air conditioner is greatly affected. The amount of heat exchange in the outer heat exchanger 3 decreases. Therefore, the degree of supercooling of the refrigerant on the outlet side of the outdoor heat exchanger 3 decreases, the refrigerant becomes a gas-liquid two-phase state, and the refrigerant flow rate passing through the expansion device 5 of the indoor unit B may extremely decrease. As a result, there is a problem that stable cooling capacity cannot be obtained. Further, since the refrigerant flow rate in the expansion device 5 decreases, the refrigerant pressure on the low-pressure side decreases, so that the refrigerant discharge temperature rises and the compressor 1 may be damaged.

The present invention has been made in view of the above-mentioned problems of the prior art. Even when operating conditions change, the refrigerant flow rate is prevented from being disturbed in the refrigeration cycle, and stable operation can always be performed. It is intended to provide an air conditioner.

[0006]

In order to achieve the above object, the present invention comprises a compressor, an outdoor heat exchanger, a throttle device, and an indoor heat exchanger, which are sequentially connected through a refrigerant pipe. In an air conditioner that includes a refrigeration cycle and controls the valve opening degree of the expansion device based on the deviation between the superheat degree of the refrigerant on the refrigerant outlet side of the indoor heat exchanger and the corresponding target superheat degree, Supercooling degree detecting means for detecting the degree of supercooling of the refrigerant on the refrigerant outlet side of the outdoor heat exchanger, and first calculating and setting a target degree of superheat according to the degree of supercooling detected by the degree of supercooling detection means. The target superheat degree setting means is used.

Further, a refrigeration cycle in which a compressor, an outdoor heat exchanger, a throttle device, and an indoor heat exchanger are sequentially connected via a refrigerant pipe is provided, and the refrigerant on the refrigerant outlet side of the indoor heat exchanger is In the air conditioner configured to control the valve opening degree of the expansion device based on the deviation between the superheat degree and the preset target superheat degree corresponding to this, in the refrigerant outlet side of the outdoor heat exchanger A subcooling degree detecting means for detecting a subcooling degree, and a first degree for calculating and setting a valve opening operation range of the expansion device according to the subcooling degree detected by the subcooling degree detecting means.
And a valve opening operating range setting means.

Further, a refrigeration cycle in which a compressor, an outdoor heat exchanger, a throttle device provided in each of a plurality of indoor units and an indoor heat exchanger are sequentially connected through a refrigerant pipe is provided, and each room is provided. In the air conditioner configured to control the valve opening degree of the expansion device based on the deviation between the superheat degree of the refrigerant on the refrigerant outlet side of the inner heat exchanger and the target superheat degree corresponding to these, in the plurality of indoor units Among them, the operating capacity detecting means for detecting the operating capacity of the operating indoor unit, the total operating capacity calculating means for calculating the sum of the operating capacities detected by the operating capacity detecting means, and the total operating capacity calculating means Second target superheat degree setting means for calculating and setting the target superheat degree according to the sum of the operating capacities is provided.

A compressor, an outdoor heat exchanger, a throttle device provided in each of a plurality of indoor units, and an indoor heat exchanger are connected in sequence through a refrigerant pipe to provide a refrigeration cycle. In the air conditioner configured to control the valve opening degree of the expansion device based on the deviation between the superheat degree of the refrigerant on the refrigerant outlet side of the inner heat exchanger and the target superheat degree set in advance corresponding to these, Of the plurality of indoor units, operating capacity detecting means for detecting the operating capacity of the operating indoor unit, total operating capacity calculating means for calculating the sum of the operating capacities detected by the operating capacity detecting means, and total operating capacity Second valve opening operation range setting means for calculating and setting the valve opening operation range of the expansion device according to the sum of the operating capacities calculated by the calculation means is provided.

[0010]

According to the air conditioner of the present invention, the valve opening degree of the expansion device is adjusted based on the deviation between the superheat degree of the gas refrigerant on the refrigerant outlet side of the indoor heat exchanger and the corresponding target superheat degree. When controlling, the subcooling degree detection means detects the subcooling degree of the liquid refrigerant on the refrigerant outlet side of the outdoor heat exchanger. Then, the first target superheat degree setting means sets and changes the target superheat degree to a large value when the detected supercooling degree is small, for example. As a result, the valve opening of the expansion device is reduced.
Along with this, the refrigerant pressure on the high pressure side rises, so that a sufficiently large degree of supercooling can be stably ensured. As a result, the flow rate of the refrigerant passing through the expansion device can be prevented from being extremely reduced, and stable operation can be performed.

Further, the valve opening degree of the expansion device is controlled on the basis of the deviation between the superheat degree of the gas refrigerant on the refrigerant outlet side of the indoor heat exchanger and a predetermined target superheat degree set correspondingly thereto. In this case, the supercooling degree detecting means detects the supercooling degree of the liquid refrigerant on the refrigerant outlet side of the outdoor heat exchanger. And
For example, when the detected degree of supercooling is small, the first valve opening operation range setting means lowers the lower limit value of the valve opening operation range of the expansion device to change the setting and further reduce the valve opening. As a result, the pressure of the refrigerant on the high pressure side rises, so that a sufficiently large degree of supercooling can be stably ensured. As a result, the flow rate of the refrigerant passing through the expansion device can be prevented from being extremely reduced, and stable operation can be performed.

Further, when the valve opening of the expansion device is controlled based on the deviation between the degree of superheat of the gas refrigerant on the refrigerant outlet side of the plurality of indoor heat exchangers and the corresponding degree of target superheat, the operating capacity is increased. The detecting means detects the operating capacity of each indoor unit in operation. Then, the total operating capacity calculation means calculates the total sum of the detected operating capacities. Therefore, the second target superheat degree setting means sets and changes the target superheat degree to a large value, for example, when the total sum of the calculated operating capacities is large. As a result, the valve opening of the expansion device is reduced.
Therefore, the pressure of the refrigerant on the high pressure side rises, so that a sufficiently large degree of supercooling can be stably ensured. as a result,
The flow rate of the refrigerant passing through the expansion device can be prevented from being extremely reduced, and stable operation can be performed.

Then, the valve opening degree of the expansion device is determined based on the deviation between the degree of superheat of the gas refrigerant on the refrigerant outlet side of the plurality of indoor heat exchangers and the predetermined target degree of superheat corresponding to these. When performing control, the operating capacity detecting means detects the operating capacity of each indoor unit in operation. Then, the total operating capacity calculation means calculates the total sum of the detected operating capacities. Therefore, the second valve opening operation range setting means is
For example, when the total sum of the calculated operating capacities is large, the lower limit value of the valve opening operation range of the expansion device is lowered and the setting is changed to further reduce the valve opening. As a result, the pressure of the refrigerant on the high pressure side rises, so that a sufficiently large degree of supercooling can be stably ensured. As a result, the flow rate of the refrigerant passing through the expansion device can be prevented from being extremely reduced, and stable operation can be performed.

[0014]

【Example】

Example 1. A first embodiment of the present invention is shown in FIGS. FIG. 1 is an overall configuration diagram showing an air conditioner of the first embodiment. In FIG. 1, A is a heat source device which is an outdoor unit, B is an indoor unit, 1 is a compressor, 2 is a four-way switching valve, 3 is an outdoor heat exchanger, 4 is an accumulator, 5 is a throttle device, and 6 is an indoor side. A heat exchanger, 7 is first pressure detecting means for detecting the refrigerant pressure in the high pressure portion of the heat source unit A, 8 is first temperature detecting means for detecting the refrigerant temperature on the liquid refrigerant side of the outdoor heat exchanger 3, Reference numeral 9 is a second temperature detecting means attached to one connection portion of the indoor heat exchanger 6 on the expansion device 5 side, and 10 is a third temperature attached to the other connection portion of the indoor heat exchanger 6. Detecting means, 11
Calculates the degree of supercooling of the liquid refrigerant from the refrigerant pressure detected by the first pressure detecting means 7 and the refrigerant temperature detected by the first temperature detecting means 8, and sets the target degree of superheat from the degree of supercooling. ,
The superheat degree of the gas refrigerant is obtained from the refrigerant temperatures detected by the second temperature detecting means 9 and the third temperature detecting means 10, respectively, and the obtained superheat degree is compared with the target superheat degree set to be changeable. And the diaphragm device 5 based on the deviation
It is a valve opening control means for controlling the valve opening. Also, FIG.
In, the solid arrow indicates the direction in which the refrigerant flows during the cooling operation.

In the air conditioner shown in FIG. 1, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is sent to the outdoor heat exchanger 3 via the four-way switching valve 2 and exchanges heat with the outdoor air. After being liquefied in, it is sent to the indoor unit B and the expansion device 5
Is depressurized by and flows into the indoor heat exchanger 6 to exchange heat with the indoor air and gasify to cool the room. Then, the gasified refrigerant returns to the heat source unit A, and is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4. In the case of such cooling operation,
The valve opening control means 11 (an example of a first target superheat degree setting means) controls the refrigerant temperature T detected by the second temperature detection means 9.
Refrigerant temperature T detected by the _second and third temperature detecting means 10.
₃ obtains the gas refrigerant superheating degree _{SH (SH = T 3 -T 2} ) from a comparison between the changeable set the superheat degree SH is the target degree of superheat SHm, SH-SHm <0 if the throttle device 5
The valve opening degree Sj is decreased, and if SH-SHm> 0, the valve opening degree Sj is increased to control the refrigerant flow rate.

At this time, the valve opening control means 11 determines the liquid refrigerant from the refrigerant pressure P ₁ detected by the first pressure detection means 7 and the refrigerant temperature T ₁ detected by the first temperature detection means 8. The degree of supercooling SC {SC = TP ₁ (refrigerant saturation temperature at pressure P ₁ ) −T ₁ } is calculated, and as shown in FIG.
Calculate and set Hm. FIG. 2 is a diagram showing the relationship between the supercooling degree SC and the target superheat degree SHm. In the figure, SC
m is a predetermined supercooling degree, SHm ₁ is a first target superheat degree, SH
m ₂ is the _second value which is larger than the first target superheat degree SHm ₁ .
Is the target superheat degree. In this case, the predetermined supercooling degree SCm is set in advance so that the supercooling degree of the liquid refrigerant flowing into the expansion device 5 can be secured at a sufficiently large value (for example, SC
m = 10), and SHm ₁ <SHm ₂ (for example, SH
m ₁ = 2, SHm ₂ = 7). That is, a configuration including the first pressure detecting means 7, the first temperature detecting means 8, and the valve opening control means 11 is an example of the supercooling degree detecting means. According to FIG. 2, the valve opening control means 1
1 indicates that if the calculated supercooling degree SC is SC <SCm, the second target superheat degree SHm ₂ is set as the target superheat degree SHm, and if SC ≧ SCm, the first target superheat degree SHm ₁ is set as the target superheat degree SHm _1. To set. When the target superheat degree SHm is set in this way, as described above, the valve opening control means 11 is based on the result of the comparison calculation with the superheat degree SH calculated from the detected temperatures T ₂ and T _3. Valve opening S
j is controlled.

FIG. 3 is a diagram showing the relationship between the valve opening degree Sj and the superheat degree SH and the supercooling degree SC. As shown in FIG. 3, for example, the calculated superheat degree SH is SHm ₁ <SH <SHm ₂
If the target superheat degree SHm is set to the first target superheat degree SHm ₁ , the valve opening degree Sj is controlled to increase. Here, since the degree of supercooling SC decreases as the valve opening degree Sj increases, it becomes impossible to secure a sufficiently large degree of supercooling of the refrigerant flowing into the expansion device 5 due to the influence of the pressure loss of the refrigerant pipe and the like. When the refrigerant becomes a gas-liquid two-phase state due to this, the refrigerant flow rate passing through the expansion device 5 is extremely reduced, and thus the cooling capacity is significantly reduced.
In addition, the discharge temperature of the compressor 1 rises due to the drawing of the low-pressure refrigerant, which may damage the compressor 1.

Therefore, as shown in FIG. 2 above, when the supercooling degree SC decreases and falls below a predetermined supercooling degree SCm, it becomes impossible to secure an appropriate subcooling degree for the operation.
By changing and setting m to the second target superheat degree SHm ₂ , the valve opening degree Sj is controlled so as to decrease. Valve opening S
When j decreases, the supercooling degree SC increases, so that a sufficient supercooling degree can be secured, the flow rate of the refrigerant passing through the expansion device 5 becomes stable, and a sufficient cooling capacity can be obtained. The relationship between the valve opening degree Sj and the superheat degree SH and the supercool degree SC shown in FIG. 3 ensures a stable supercool degree in accordance with changes in operating conditions (for example, indoor air conditions, outdoor air conditions, etc.). It also indicates that the valve opening degree Sj for the change also changes. Therefore, by performing the control described above, it is possible to appropriately cope with such a change in the operating condition, and perform an operation in which a stable cooling capacity is always secured.

Next, the control operation of the valve opening during the cooling operation will be described with reference to the flow chart shown in FIG. Step two
At 0, the refrigerant pressure P ₁ is detected by the first pressure detecting means 7, and the routine proceeds to step 21. In step 21, the first temperature detection means 8 detects the refrigerant temperature T _1, and the process proceeds to step 22. In step 22, the degree of supercooling SC of the refrigerant is calculated from the detected refrigerant pressure P ₁ and refrigerant temperature T _1, and the process proceeds to step 23. In step 23, the calculated supercooling degree SC of the refrigerant is compared with a preset predetermined supercooling degree SCm, and when the supercooling degree SC is smaller (Ye
s), the process proceeds to step 24. If the supercooling degree SC is larger (No), the process proceeds to step 25. Step 24
Then, the second target superheat degree SHm is set as the target superheat degree SHm.
Set ₂ and proceed to step 26. In step 25,
The first target superheat degree SHm ₁ is set as the target superheat degree SHm, and the routine proceeds to step 26. In step 26, the refrigerant temperature T ₂ is detected by the second temperature detecting means 9, and in step 27
Go to. In step 27, the refrigerant temperature T ₃ is detected by the third temperature detecting means 10, and the process proceeds to step 28. In step 28, the superheat degree SH of the refrigerant is calculated from the detected refrigerant temperatures T ₂ and T _3, and the process proceeds to step 29. Step two
In 9, the calculated superheat degree SH is compared with the target superheat degree SHm set at that time, and if the superheat degree SH is smaller (Yes), the process proceeds to step 30 to superheat degree S.
If H is larger (No), the process proceeds to step 31. In step 30, the valve opening degree Sj of the expansion device 5 is decreased, and the process returns to step 20. In step 31, the calculated superheat degree SH and the set target superheat degree SHm are compared, and when the superheat degree SH is larger (Yes), the process proceeds to step 32, and when the superheat degree SH is smaller. To (N
o), go to step 33. In step 32, the valve opening degree Sj of the expansion device 5 is increased, and the process returns to step 20.
In step 33, the valve opening degree Sj of the expansion device 5 is not changed as it is, and the process returns to step 20. As described above, the valve opening control means 11 controls the valve opening Sj of the expansion device.

Example 2. Embodiment 2 according to the present invention is shown in FIG.
8 to 8. FIG. 5 is an overall configuration diagram showing the air conditioner of the second embodiment, and the same portions as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Further, in FIG. 5, solid arrows indicate the direction in which the refrigerant flows during the cooling operation.

In the air conditioner shown in FIG. 5, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is sent to the outdoor heat exchanger 3 via the four-way switching valve 2 and exchanges heat with the outdoor air. After being liquefied in, it is sent to the indoor unit B and the expansion device 5
Is depressurized by and flows into the indoor heat exchanger 6 to exchange heat with the indoor air and gasify to cool the room. Then, the gasified refrigerant returns to the heat source unit A, and is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4. In the case of such cooling operation,
The valve opening control means 11 a (an example of a first valve opening operation range setting means) is a refrigerant temperature T ₂ detected by the second temperature detection means 9 and a refrigerant detected by the third temperature detection means 10. Superheat degree SH of gas refrigerant from temperature T ₃ (SH = T ₃ −T ₂ ).
And the target superheat degree SHm
When SH-SHm <0, the valve opening degree Sj of the expansion device 5 is decreased, and when SH-SHm> 0, the valve opening degree Sj is decreased.
To control the refrigerant flow rate. At this time, the target superheat degree SHm is set in advance as an appropriate value that can ensure a sufficient cooling capacity (for example, SHm = 7).

In this case, the valve opening Sj operates within the set operating range. That is, even if the valve opening degree Sj is operating in the state of SH-SHm <0, for example, when the indoor air temperature is low and the cooling load is small, the heat exchange capacity decreases and the superheat degree SH of the refrigerant is reduced. Difficult to attach. However, if the valve opening degree Sj is reduced too much, the cooling capacity may decrease due to the decrease in the flow rate of the refrigerant, and the discharge temperature of the compressor 1 may increase due to the drawing of the low-pressure refrigerant, resulting in damage to the compressor 1. is there.

Therefore, by setting the minimum valve opening degree Sjn as the valve opening degree Sj, such a situation is prevented from occurring. On the contrary, even if the valve opening degree Sj is increased in the state of SH-SHm> 0, for example, when the indoor air temperature is high and the cooling load is large, the heat exchange capacity is increased and the superheat degree SH of the refrigerant is increased. Tends to grow. However, if the valve opening degree Sj is increased too much, the refrigerant pressure on the high-pressure side is reduced and the degree of supercooling is less likely to increase. As a result, the refrigerant flow rate is decreased to reduce the cooling capacity, and the compression due to the drawing of the low-pressure refrigerant is performed. The discharge temperature of the compressor 1 rises and the compressor 1
May be damaged. Therefore, such a situation is prevented by setting the maximum valve opening degree Sjx to the valve opening degree Sj.

At this time, the valve opening control means 11a uses the first
From the refrigerant pressure P ₁ detected by the pressure detecting means 7 and the refrigerant temperature T ₁ detected by the first temperature detecting means 8 to the supercooling degree SC {SC = TP ₁ (refrigerant saturation temperature at pressure P ₁ ) -T ₁ } is calculated, and as shown in FIG.
Set the operating range of. FIG. 6 is a diagram showing a relationship between the degree of supercooling SC and the minimum valve opening degree Sjn. In FIG. 6, SC
m is a predetermined supercooling degree, Sjn ₁ is a first minimum valve opening degree, Sjn
n ₂ is the second minimum valve opening degree. In this case, the predetermined supercooling degree SCm is set so that the supercooling degree of the liquid refrigerant flowing into the expansion device 5 can be sufficiently secured (for example, SCm =
10) and Sjn ₁ <Sjn ₂ . According to FIG. 6, the calculated supercooling degree SC is SC <
If SCm, the second minimum valve opening Sjn ₂ is set as the minimum valve opening Sjn, and if SC ≧ SCm, the minimum valve opening Sjn is set.
The first minimum valve opening Sjn ₁ is set as n. While the minimum valve opening Sjn is set as described above, the maximum valve opening S
jx is the difference ΔSj (ΔSj = Sj from the minimum valve opening Sjn).
x-Sjn) is set to be constant. That is, a configuration including the first pressure detecting means 7, the first temperature detecting means 8, and the valve opening control means 11 is an example of the supercooling temperature detecting means.

FIG. 7 is a diagram showing the relationship between the valve opening degree Sj and the superheat degree SH and the supercooling degree SC. According to FIG. 7, for example, the calculated superheat degree SH is SH <SHm, and the valve opening degree Sj is Sj.
> Sjn ₂ , the minimum valve opening Sjn
Is set to the second minimum valve opening degree Sjn ₂ , the valve opening degree Sj is regulated to be small as described above. However, the minimum valve opening Sjn is set to the minimum valve opening Sjn ₂ second valve opening signal Sj can not be reduced only to the minimum valve opening Sjn ₂ of the second, in the valve opening degree is excessive The degree of cooling SC is too small to fall below the predetermined degree of supercooling SCm, and a proper degree of supercooling cannot be secured for operation.

Therefore, as described above with reference to FIG. 6, by setting the minimum valve opening degree to the first minimum valve opening degree Sjn ₁ , the valve opening degree Sj is further reduced and the sufficient supercooling degree SC is achieved.
Can be secured. The relationship between the valve opening degree Sj and the superheat degree SH and the supercooling degree SC shown in FIG.
It is shown that the valve opening degree Sj for ensuring a stable degree of supercooling also changes with changes in the indoor air condition, the outdoor air condition, etc.). By performing the control described above, it is possible to appropriately respond to such changes in operating conditions,
It is possible to perform an operation in which a stable cooling capacity is always secured.

Next, the control operation of the valve opening during the cooling operation will be described with reference to the flow chart shown in FIG. Step 3
In 4, the first pressure detecting means 7 detects the refrigerant pressure P ₁ and the process proceeds to step 35. In step 35, the first temperature detecting means 8 detects the refrigerant temperature T _1, and the process proceeds to step 36. In step 36, the degree of supercooling SC of the refrigerant is calculated from the detected refrigerant pressure P ₁ and refrigerant temperature T _1, and the process proceeds to step 37. In step 37, the calculated supercooling degree SC of the refrigerant is compared with a preset predetermined supercooling degree SCm, and when the supercooling degree SC is smaller (Ye
s), the process proceeds to step 38, and if the supercooling degree SC is larger (No), the process proceeds to step 39. Step 38
Then, as the minimum valve opening degree Sjn, the first minimum valve opening degree Sjn is set.
Set ₁ and proceed to step 40. In step 39,
The second target superheat degree Sjn ₂ is set as the target superheat degree Sjn, and the routine proceeds to step 40. In step 40, the second temperature detecting means 9 detects the refrigerant temperature T ₂ , and in step 41
Go to. In step 41, the refrigerant temperature T ₃ is detected by the third temperature detecting means 10, and the process proceeds to step 42. At step 42, the superheat degree SH of the refrigerant is calculated from the detected refrigerant temperatures T ₂ and T _3, and the routine proceeds to step 43. Step 4
In 3, the calculated superheat degree SH is compared with a predetermined target superheat degree SHm set in advance. If the superheat degree SH is smaller (Yes), the process proceeds to step 44, and the superheat degree SH is determined. If is larger (No), the process proceeds to step 45. In step 44, the valve opening degree Sj of the expansion device 5 is decreased, and the process returns to step 34. In step 45, the calculated superheat degree SH and the preset target superheat degree SHm are set.
If the superheat degree SH is larger than (Ye
s), the process proceeds to step 46, and when the superheat degree SH is smaller (No), the process proceeds to step 47. In step 46, the valve opening degree Sj of the expansion device 5 is increased, and step 3
Return to 4. In step 47, the valve opening Sj of the expansion device 5
Is not changed and the process returns to step 34. As described above, the valve opening control means 11a controls the valve opening Sj of the expansion device.

Example 3. FIG. 9 shows a third embodiment according to the present invention.
Through FIG. FIG. 9 is an overall configuration diagram showing the air conditioner of the third embodiment, and the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 9, B ₁ is a first indoor unit and B ₂ is a second indoor unit. Although only two indoor units are shown here, the same applies to the case where there are three or more indoor units. Further, in FIG. 9, solid arrows indicate the direction in which the refrigerant flows during the cooling operation.

In the air conditioner shown in FIG. 9, the high-temperature high-pressure gas refrigerant discharged from the compressor 1 is sent to the outdoor heat exchanger 3 via the four-way switching valve 2 and exchanges heat with the outdoor air. After being liquefied by, it is sent to the respective indoor units B ₁ and B ₂ , decompressed by the respective expansion devices 5, flows into the indoor heat exchanger 6, exchanges heat with the indoor air, is gasified, and cools each indoor. To do. Then, the gasified refrigerant returns to the heat source unit A, and is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4. In the case of such a cooling operation, the valve opening control means 11b (an example of the second target superheat degree setting means, see FIG. 10) has the refrigerant temperature T ₂ and the refrigerant temperature T ₂ detected by the second temperature detection means 9, respectively. From the refrigerant temperature T ₃ detected by the third temperature detecting means 10, the superheat degree SH of the gas refrigerant (SH = T ₃ −
T ₂ ) is calculated, and those superheat degrees SH are compared with the target superheat degree SHm that is set to be changeable, and SH-SHm <0.
If so, the valve opening degree Sj of the expansion device 5 is decreased, and SH-SH
If m> 0, the valve opening Sj is increased to control the refrigerant flow rate. At this time, the target superheat degree SHm is variably set so as to be an appropriate value that can secure a sufficient cooling capacity (for example, SHm = 7).

Further, FIG. 10 shows the indoor units B ₁ and B
₂ is a block diagram showing a valve opening control mechanism of the expansion device 5 of FIG. In the figure, 12 is a driving signal transmitting means for outputting a driving signal for specifying the indoor unit in operation, 13 is a capacity signal transmitting means for outputting a capacity signal of the indoor unit in operation, and 14 is each indoor unit B ₁ , B ₂ to receive the operation signal and the capacity signal, and calculate the total operation capacity of the entire refrigeration cycle. The operation signal transmitting means 12
The configuration including the capacity signal transmitting means 13 is an example of the operating capacity detecting means.

At this time, the valve opening control means 11b, based on the information on the sum of the operating capacities of the operating indoor units obtained from the total operating capacity calculating means 14, as shown in FIG. 11, the target superheat degree SHm. Is calculated and set to be changeable. FIG. 11 shows the relationship between the operating capacity Qj and the target superheat degree SHm. In the figure, Qjm is a predetermined operating capacity (for example, a capacity of 100% of the outdoor unit capacity), SHm ₁ is a first target superheat degree, SHm ₂ is a second target superheat degree, and in this case,
SHm ₁ <SHm ₂ (for example, SHm ₁ = 2, SHm ₂
= 7). According to FIG. 11, if the sum Qj of operating capacities is Qj <Qjm, the target superheat degree SHm
The first target superheat degree SHm ₁ is set as
If m, the target superheat degree SHm is set as the second target superheat degree SH.
Set m ₂ . When the target superheat degree SHm is set in this way, as described above, the detected refrigerant temperature T
The valve opening degree Sj of the expansion device 5 is controlled based on the result of the comparison calculation with the superheat degree SH calculated from ₂ and T ₃ .

FIG. 12 shows the relationship between the total operating capacity Qj and the degree of supercooling SC. According to the figure, as the total sum Qj of the operating capacities becomes larger, the degree of throttling of the entire refrigeration cycle (that is, the sum of the valve opening degrees Sj of the respective throttling devices 5) becomes too large, and the refrigerant pressure on the high pressure side decreases. Therefore, it is difficult to secure a sufficient degree of supercooling. Here, SCm is a predetermined degree of supercooling that is preset so as to ensure a sufficient degree of supercooling of the liquid refrigerant flowing into the expansion device 5 (for example, SCm = 10). Further, for example, the total sum Qj of the calculated operating capacities is Qj> Qjm.
If it is in the state of (predetermined operating capacity), the target superheat S
When Hm is set to the first target superheat degree SHm ₁ , the supercool degree SC does not reach the supercool degree SCm that can secure a sufficient cooling capacity. That is, each indoor unit B
Due to pressure loss and the like in the refrigerant pipes up to ₁ and B ₂ , the refrigerant flowing into each expansion device 5 is in a gas-liquid two-phase state, and the refrigerant flow rate passing through the expansion device 5 is extremely reduced, resulting in a significant cooling capacity. There is a possibility that the compressor 1 may be damaged due to a decrease in temperature or an increase in the discharge temperature of the compressor 1 due to the drawing of the low-pressure refrigerant.

Therefore, as shown in FIG. 11 above, when the total operating capacity Qj increases and exceeds the predetermined operating capacity Qjm and an appropriate degree of supercooling cannot be secured, the target degree of superheat SHm is set to the first value. By changing the setting from the target superheat degree SHm ₁ to the second target superheat degree SHm ₂ , each indoor unit B
The valve openings Sj of ₁ and B ₂ are controlled so as to decrease. When the valve opening degree Sj decreases, the supercooling degree SC increases,
A sufficient degree of subcooling of the liquid refrigerant flowing into the expansion device 5 can be secured, and stable cooling capacity can be obtained.

Next, the control operation of the valve opening during the cooling operation will be described with reference to the flow chart shown in FIG. In step 48, the sum total Qj of the operating capacities is calculated by receiving the operating signals and the capacity signals from the indoor units B ₁ and B ₂ , and step 4
Proceed to 9. In step 49, the calculated total sum Qj of the operating capacities is compared with a preset predetermined operating capacity Qjm, and if the total sum Qj of the operating capacities is smaller (Ye
s), the process proceeds to step 50, and when the total operating capacity Qj is larger (No), the process proceeds to step 51. At step 50, the first target superheat degree SHm ₁ is set as the target superheat degree SHm, and the routine proceeds to step 52. Step 51
Then, the second target superheat degree SHm is set as the target superheat degree SHm.
Set ₂ and proceed to step 52. In step 52,
The refrigerant temperature T ₂ is detected by the second temperature detecting means 9, and the routine proceeds to step 53. In step 53, the third temperature detecting means 10 detects the refrigerant temperature T _3, and the process proceeds to step 54. At step 54, the superheat degree SH of the refrigerant is calculated from the detected refrigerant temperatures T ₂ and T _3, and the routine proceeds to step 55. In step 55, the calculated superheat degree SH and the target superheat degree SHm set at that time are compared. If the superheat degree SH is smaller (Yes), the process proceeds to step 56, and the superheat degree SH is determined. Is larger (No), step 57
Go to. In step 56, the valve opening degree Sj of the expansion device 5 is decreased, and the process returns to step 48. In step 57, the calculated superheat degree SH is compared with the set target superheat degree SHm, and if the superheat degree SH is larger (Yes),
When the degree of superheat SH is smaller (No), the process proceeds to step 59. In step 58, the valve opening degree Sj of each expansion device 5 is increased, and the process returns to step 48. In step 59, the valve opening degree Sj of the expansion device 5 is not changed as it is, and the process returns to step 48. As described above, the valve opening control means 11b controls the valve opening Sj of the expansion device 5.

Example 4. FIG. 1 shows a fourth embodiment according to the present invention.
4 to FIG. FIG. 14 is an overall configuration diagram showing an air conditioner of a fourth embodiment, and the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 14, B ₁ is a first indoor unit and B ₂ is a second indoor unit. here,
Although only two indoor units are shown, the same applies when the number of indoor units is three or more. Further, in FIG. 14, solid line arrows indicate the direction in which the refrigerant flows during the cooling operation.

In the air conditioner shown in FIG. 14, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is sent to the outdoor heat exchanger 3 via the four-way switching valve 2 and exchanges heat with the outdoor air. After being liquefied in, each indoor unit B ₁ , B ₂
Is sent to the indoor heat exchanger 6 to be heat-exchanged with the indoor air and gasified to cool each room. The gasified refrigerant is the heat source unit A.
Back to the four-way switching valve 2, accumulator 4 and compressor 1
Inhaled into. In such a cooling operation, the valve opening control means 11c (an example of the second valve opening operation range setting means, see FIG. 15) causes the refrigerant temperature T ₂ detected by the second temperature detection means 9 and From the refrigerant temperature T ₃ detected by the third temperature detecting means 10, the superheat degree SH of the gas refrigerant (SH = T ₃ −T)
₂ ) is obtained, the superheat degree SH1 is compared with a predetermined target superheat degree SHm set in advance, and if SH-SHm <0, the valve opening degree Sj of the expansion device 5 is decreased, and SH-SHm> 0.
If so, the valve opening Sj is increased to control the refrigerant flow rate. At this time, the target superheat degree SHm is set in advance as an appropriate value that can ensure a sufficient cooling capacity (for example, SHm = 7).

In this case, the valve opening Sj operates within the set operating range. That is, even if the valve opening degree Sj is reduced in the state of SH-SHm <0, for example, when the indoor air temperature is low and the cooling load is small, the heat exchange capacity decreases and the degree of superheat of the refrigerant decreases. SH is hard to attach. However, if the valve opening degree Sj is excessively reduced, there is a possibility that the cooling capacity is reduced due to the reduction of the refrigerant flow rate, and the discharge temperature of the compressor 1 is increased due to the drawing of the low-pressure refrigerant, resulting in damage to the compressor 1. There is.

Therefore, such a problem is prevented by setting the minimum valve opening degree Sjn to the valve opening degree Sj. On the contrary, even if the valve opening Sj is operated to increase in the state of SH-SHm> 0, for example, when the indoor air temperature is high and the cooling load is large, the heat exchange capacity increases and the degree of superheat of the refrigerant increases. It is easy to increase SH. However, if the valve opening degree Sj is increased too much, the refrigerant pressure on the high-pressure side is reduced and the degree of supercooling is less likely to increase. As a result, the refrigerant flow rate is decreased to reduce the cooling capacity and the compression due to the drawing of the low-pressure refrigerant is performed. In some cases, the discharge temperature of the machine 1 rises and the compressor 1 is damaged. Therefore, the above-mentioned inconvenience is prevented by setting the maximum valve opening Sjx to the valve opening Sj. Further, FIG. 15 shows that each indoor unit B ₁ ,
Is a block diagram showing the control mechanism of the valve opening degree of the throttle device 5 B _2. Here, 12 is an operation signal transmission means, 13 is a capacity signal transmission means, 14 is each indoor unit B _{1 in operation} ,
It is a total operating capacity calculation means for receiving the operating signal and the capacity signal from B ₂ and calculating the total operating capacity of the entire refrigeration cycle. Further, the configuration including the operation signal transmission means 12 and the capacity signal transmission means 13 is an example of the operation capacity detection means.

At this time, the valve opening control means 11c calculates and sets the operating range of the valve opening Sj as shown in FIG. 16 based on the information of the total operating capacity Qj from the operating capacity calculating means 14. . FIG. 16 is a diagram showing the relationship between the total operating capacity Qj and the minimum valve opening degree Sjn. In the figure, Qjm
Is the specified operating capacity (for example, 100% of the outdoor unit capacity)
Capacity), Sjn ₁ is the first minimum valve opening degree, Sjn ₂ is the second minimum valve opening degree, and Sjn ₁ <Sjn ₂ is satisfied. According to FIG. 16, if the sum Qj of operating capacities is Qj <Qjm, the second minimum valve opening Sjn ₂ is set as the minimum valve opening Sjn, and if Qj ≧ Qjm, the minimum minimum valve opening Sjn is set as the first minimum. Set the valve opening Sjn ₁ .
In this way, the minimum valve opening Sjn is set, while the maximum valve opening Sjx is different from the minimum valve opening Sjn by a difference ΔSj (ΔSj
= Sjx-Sjn) is set to be constant.

FIG. 17 shows the relationship between the total operating capacity Qj and the degree of supercooling SC. As the total operating capacity Qj increases, the degree of throttling of the entire refrigeration cycle (ie,
This indicates that the sum of the valve opening Sj of each expansion device 5) becomes large, the refrigerant pressure on the high pressure side decreases, and it becomes difficult to secure the supercooling degree SC. Here, SCm is a predetermined degree of supercooling that is set in advance so as to ensure a sufficient degree of supercooling of the liquid refrigerant flowing into each expansion device 5 (for example, S
Cm = 10). Further, for example, the total sum Q of the calculated operating capacities
If j is Qj> Qjm, the minimum valve opening S
When jn is set to the second minimum valve opening degree Sjn ₂ , the subcooling degree SC has not reached the subcooling degree SCm at which sufficient cooling capacity can be secured. That is, due to the pressure loss of the refrigerant pipes to the indoor units B ₁ and B ₂ , the refrigerant flowing into each expansion device 5 is in a gas-liquid two-phase state, and the flow rate of the refrigerant passing through each expansion device 5 is extremely reduced. There is a possibility that the cooling capacity is significantly reduced by the above, or the discharge temperature of the compressor 1 rises due to the drawing of the low-pressure refrigerant and the compressor 1 is damaged.

Therefore, as shown in FIG. 16, when the total operating capacity Qj increases and exceeds the predetermined operating capacity Qjm and an appropriate degree of subcooling cannot be ensured, the minimum valve opening S
By setting jn to the first minimum valve opening degree Sjn ₁ , the valve opening degree Sj of each indoor unit B ₁ , B ₂ is controlled to decrease. As the valve opening degree Sj decreases in this way, the supercooling degree SC increases, so that the subcooling degree of the liquid refrigerant flowing into each expansion device 5 can be sufficiently secured, and a stable cooling capacity can be obtained.

Next, the control operation of the valve opening during the cooling operation will be described with reference to the flow chart shown in FIG. In step 60, the sum Qj of the operating capacities is calculated based on the information of the operating signals and the capacity signals from the indoor units B ₁ and B _2, and the process proceeds to step 61. In step 61, the total sum Qj of the calculated operating capacities and the predetermined operating capacity Qj set in advance.
If the total sum Qj of the operating capacities is smaller (Yes), the process proceeds to step 62, where the total sum Q of the operating capacities is compared.
If j is larger (No), the process proceeds to step 63. At step 62, the first minimum valve opening Sjn ₁ is set as the minimum valve opening Sjn, and the routine proceeds to step 64. At step 63, the second minimum valve opening Sjn ₂ is set as the minimum valve opening Sjn, and the routine proceeds to step 64. In step 64, the coolant temperature T ₂ is detected by the second temperature detecting means 9, and the process proceeds to step 65. In step 65, the refrigerant temperature T ₃ is detected by the third temperature detecting means 10, and in step 66
Go to. At step 66, the superheat degree SH of the refrigerant is calculated from the detected refrigerant temperatures T ₂ and T _3, and the routine proceeds to step 67. In step 67, the calculated superheat degree SH is compared with a preset target superheat degree SHm. If the superheat degree SH is smaller (Yes), the process proceeds to step 68.
If the superheat degree SH is larger (No), step 6
Proceed to 9. In step 68, the valve opening S of each expansion device 5
Decrease j and return to step 60. In step 69, the calculated superheat degree SH and the preset target superheat degree SHm are compared. If the superheat degree SH is larger (Yes), the process proceeds to step 70, and the superheat degree SH is smaller. If (No), the process proceeds to step 71. In step 70, the valve opening degree Sj of each expansion device 5 is increased, and the process returns to step 60. In step 71, the valve opening degree Sj of each expansion device 5 is not changed as it is, and step 60
Return to. As described above, the valve opening control means 11c controls the valve opening Sj of each throttle device 5.

[0043]

According to the air conditioner of the present invention, the valve opening of the expansion device is opened based on the deviation between the degree of superheat of the refrigerant detected on the refrigerant outlet side of the indoor heat exchanger and its target degree of superheat. When controlling the temperature, the target superheat degree is changed according to the degree of supercooling of the refrigerant on the outlet side of the outdoor heat exchanger, so the operating conditions of the refrigeration cycle have changed due to changes in air conditions, etc. Even in such a case, since the degree of supercooling of the liquid refrigerant flowing into the expansion device can be sufficiently secured, it is possible to prevent the cooling capacity from being lowered. Further, it is possible to prevent damage to the compressor due to a rise in discharge temperature caused by drawing in the low-pressure gas refrigerant.

In the case of controlling the valve opening of the expansion device based on the deviation between the degree of superheat of the refrigerant detected on the refrigerant outlet side of the indoor heat exchanger and the preset target degree of superheat, Since the operating range of the valve opening is set and changed according to the degree of supercooling of the refrigerant on the outlet side of the outdoor heat exchanger, even if the operating conditions of the refrigeration cycle change due to changes in air conditions, etc. Since the degree of supercooling of the liquid refrigerant flowing into the expansion device can be sufficiently ensured, it is possible to prevent the cooling capacity from decreasing. Further, it is possible to prevent damage to the compressor due to the rise in the discharge temperature due to the low-pressure drawing of the gas refrigerant.

Further, it has a plurality of indoor units each having an indoor heat exchanger and a throttle device, and the degree of superheat of the refrigerant detected at the refrigerant outlet side of each indoor heat exchanger and the corresponding degree. In the case of controlling the valve opening of the expansion device based on the deviation from the target superheat degree, the target superheat degree is set and changed according to the total operating capacity of the operating indoor units. Even if the operating conditions of the refrigeration cycle change due to changes in conditions, etc., it is possible to sufficiently secure the degree of subcooling of the liquid refrigerant flowing into each expansion device, and therefore it is possible to prevent the cooling capacity from decreasing. Further, it is possible to prevent damage to the compressor due to the rise in the discharge temperature due to the low-pressure drawing of the gas refrigerant.

The indoor heat exchanger and the expansion device are provided in a plurality of indoor units, and the degree of superheat of the refrigerant detected at the refrigerant outlet side of each indoor heat exchanger is preset. When controlling the valve opening of the expansion device based on the deviation from the target superheat degree, the operating range of the valve opening is set and changed according to the total operating capacity of the indoor units in operation. Even when the operating conditions of the refrigeration cycle change due to changes in the air conditions, for example, the degree of subcooling of the liquid refrigerant flowing into each expansion device can be sufficiently ensured, so that the cooling capacity can be prevented from decreasing. Further, it is possible to prevent damage to the compressor due to the rise in the discharge temperature due to the low-pressure drawing of the gas refrigerant.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a supercooling degree and a target superheat degree of the air conditioner according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a valve opening degree and a superheat degree and a supercool degree in the air conditioner according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing the control of the valve opening degree of the air conditioner according to the first embodiment of the present invention.

FIG. 5 is an overall configuration diagram of an air conditioner according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a degree of supercooling and a minimum valve opening degree of an air conditioner according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a valve opening degree and a superheat degree and a supercool degree in an air conditioner according to a second embodiment of the present invention.

FIG. 8 is a flowchart showing control of a valve opening degree of the air conditioner according to the second embodiment of the present invention.

FIG. 9 is an overall configuration diagram of an air conditioner according to a third embodiment of the present invention.

FIG. 10 is a block diagram showing a control mechanism of an air conditioner according to a third embodiment of the present invention.

FIG. 11 is a diagram showing the relationship between the operating capacity and the target degree of superheat of the air conditioner according to the third embodiment of the present invention.

FIG. 12 is a diagram showing the relationship between the operating capacity and the degree of supercooling of the air conditioner according to the third embodiment of the present invention.

FIG. 13 is a flowchart showing control of a valve opening degree of an air conditioner according to a third embodiment of the present invention.

FIG. 14 is an overall configuration diagram of an air conditioner according to a fourth embodiment of the present invention.

FIG. 15 is a block diagram showing a control mechanism of the air-conditioning apparatus according to Embodiment 4 of the present invention.

FIG. 16 is a diagram showing the relationship between the operating capacity and the minimum valve opening of the air-conditioning apparatus according to Embodiment 4 of the present invention.

FIG. 17 is a diagram showing the relationship between the operating capacity and the degree of supercooling of the air-conditioning apparatus according to Embodiment 4 of the present invention.

FIG. 18 is a flowchart showing control of the valve opening of the air-conditioning apparatus according to Embodiment 4 of the present invention.

FIG. 19 is an overall configuration diagram of an air conditioner according to a conventional technique of the present invention.

[Explanation of symbols]

A heat source unit (outdoor unit) B indoor unit B ₁ indoor unit B ₂ indoor unit 1 compressor 2 four-way switching valve 3 outdoor heat exchanger 5 throttling device 6 indoor heat exchanger 7 first pressure detection means 8 first Temperature detection means 9 second temperature detection means 10 third temperature detection means 11 valve opening control means 11a valve opening control means 11b valve opening control means 11c valve opening control means 12 operation signal transmission means 13 capacity signal Transmission means 14 Total operating capacity calculation means

Claims (4)

[Claims] 1. A refrigeration cycle comprising a compressor, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger, which are sequentially connected via a refrigerant pipe, and a refrigerant at a refrigerant outlet side of the indoor heat exchanger. In the air conditioner configured to control the valve opening degree of the expansion device based on the deviation between the superheat degree and the target superheat degree corresponding thereto, supercooling of the refrigerant on the refrigerant outlet side of the outdoor heat exchanger. Supercooling degree detecting means for detecting the degree,
An air conditioner comprising: first target superheat degree setting means for calculating and setting the target superheat degree according to the supercool degree detected by the supercool degree detecting means. 2. A refrigeration cycle comprising a compressor, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger, which are sequentially connected via a refrigerant pipe, and a refrigerant at a refrigerant outlet side of the indoor heat exchanger. In the air conditioner configured to control the valve opening of the expansion device based on the deviation between the degree of superheat and the target degree of superheat set in advance corresponding thereto, in the refrigerant outlet side of the outdoor heat exchanger. And a first valve for calculating and setting the valve opening operation range of the expansion device according to the degree of supercooling detected by the degree of supercooling detected by the degree of supercooling detection means. An air conditioner characterized by being provided with opening degree operation range setting means. 3. A refrigeration cycle in which a compressor, an outdoor heat exchanger, a throttle device provided in each of a plurality of indoor units, and an indoor heat exchanger are sequentially connected via a refrigerant pipe,
In the air conditioner configured to control the valve opening of the throttle device based on the deviation between the superheat degree of the refrigerant on the refrigerant outlet side of each of the indoor heat exchangers and the target superheat degree corresponding to these, An operating capacity detecting means for detecting an operating capacity of an operating indoor unit among the plurality of indoor sides; a total operating capacity calculating means for calculating a sum of the operating capacities detected by the operating capacity detecting means; An air conditioner comprising: second target superheat degree setting means for calculating and setting the target superheat degree according to the total sum of the operating capacities calculated by the total operating capacity calculator. 4. A refrigeration cycle in which a compressor, an outdoor heat exchanger, a throttle device provided in each of a plurality of indoor units, and an indoor heat exchanger are sequentially connected via a refrigerant pipe,
The degree of valve opening of the expansion device is controlled based on the deviation between the degree of superheat of the refrigerant on the refrigerant outlet side of each of the indoor heat exchangers and the target degree of superheat set in advance corresponding thereto. In the air conditioner, among the plurality of indoor units, an operating capacity detecting unit that detects an operating capacity related to the indoor side in operation, and a total operating capacity that calculates the sum of the operating capacities detected by the operating capacity detecting unit. Computing means,
Second valve opening operation range setting means for calculating and setting the valve opening operation range of the expansion device according to the sum of the operating capacities calculated by the total operating capacity calculation means is provided. Air conditioner.