JP2000274779A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air conditioner in which operation can be switched between refrigerant pump cycle and compression cycle under most suitable environment by making a switch from the refrigerant pump cycle to the compression cycle when the outdoor temperature exceeds a set level. SOLUTION: During compression cycle operation, a refrigerant pump bypass valve 3 is opened, a compressor bypass valve 7 and an expansion valve bypass valve 10 are closed to deliver gas refrigerant from a compressor 5 through a condenser 8 and an expansion valve 9 to an evaporator 4 thus cooling the indoor air. During refrigerant pump cycle operation, the refrigerant pump bypass valve 3 is closed and other bypass valves 7, 10 are opened to deliver gas refrigerant from the evaporator 4, as it is, to the condenser 8 where it is liquefied and fed to a refrigerant pump 1. When switching is made from compression cycle to refrigerant pump cycle when the outdoor temperature detected by an outdoor temperature sensor 15 exceeds a set level thus ensuring stabilized switching.

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 a high heat generating device which needs to be cooled even when the outside air temperature is low. The present invention relates to an annual cooling type air conditioner having a refrigerant pump for cooling.

[0002]

2. Description of the Related Art In general, as an indoor cooling method, there is an air conditioner using a compression refrigeration cycle. The cooling principle of the present air conditioner will be described below. The gas refrigerant is pressurized by compression and sent to the condenser as a high-temperature and high-pressure gas, where the refrigerant exchanges heat with outside air to liquefy the refrigerant. The liquid refrigerant is decompressed by the expansion valve and enters the evaporator, or cools the indoor air in the evaporator to gasify the refrigerant and return to the compressor. Hereinafter, by repeating this cycle, the indoor heat is released to the atmosphere through the evaporator and the condenser to cool the indoor.

When the outside air temperature is low, the cooling operation can be performed only by circulating the refrigerant by the refrigerant pump without operating the compressor. This method is called indirect outside air cooling because the refrigerant is once cooled by outside air and the room is cooled by the cooled refrigerant. Although water may be used as the circulating medium, if a refrigerant is used, the phase change can be used, so that the pump power can be reduced by reducing the amount of circulation.

[0004] A cooling cycle in the indirect outside air cooling will be described below. The gas refrigerant that has exited the evaporator is sent to the condenser as it is, cooled and liquefied by low-temperature outside air in the condenser, and sent to the refrigerant pump. In the refrigerant pump, the liquid refrigerant is pressurized and guided to the evaporator. In the evaporator, the refrigerant is gasified by cooling the indoor air, and returns to the condenser again. Hereinafter, this cycle is repeated, and indoor heat is released by releasing indoor heat to the atmosphere via an evaporator and a condenser.

[0005]

In view of the above, it is efficient to operate in a compression cycle when the outside air temperature is high and to operate in a refrigerant pump cycle when the outside air temperature is low. However, until now, the setting of more specific criteria or the operation method for switching between the two cycles has not been determined.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air conditioner capable of realizing a refrigerant pump cycle and a compression cycle, from the refrigerant pump cycle to the compression cycle under the most preferable environment. It is an object of the present invention to provide an air conditioner capable of performing the operation switching.

[0007]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the air conditioner according to claim 1 includes a refrigerant circuit in which a refrigerant pump, an expansion valve, an indoor heat exchanger, a compressor, and an outdoor heat exchanger are sequentially connected, and operates the refrigerant pump in the refrigerant circuit. An air conditioner capable of realizing a refrigerant pump cycle for performing indoor cooling and a compression cycle for performing indoor cooling by operating the compressor, wherein when the outside air temperature is equal to or higher than a set value, the refrigerant A control device for switching operation from a pump cycle to the compression cycle is provided.

This air conditioner switches the operation from the refrigerant pump cycle to the compression cycle based on the outside air temperature. That is, when the outside air temperature becomes sufficiently high, the cooling capacity of the refrigerant pump decreases, and in that case, a compression cycle operation with a high cooling capacity is performed. An advantageous operation can be performed from the viewpoint of the indoor cooling efficiency.

An air conditioner according to a second aspect of the present invention is an air conditioner having the same premise as the air conditioner according to the first aspect of the present invention, wherein the amount of air blown by the outdoor blower attached to the outdoor heat exchanger is increased. And a controller that switches the operation from the refrigerant pump cycle to the compression cycle when the indoor temperature is equal to or higher than a set value.

In this air conditioner, the operation is switched from the refrigerant pump cycle to the compression cycle based on the amount of air blown by the outdoor blower and the indoor temperature as criteria. In such a case, the fact that the outdoor air blowing amount is the maximum and the indoor temperature is equal to or higher than the set value means that, in other words, the indoor cooling is limited even though the maximum cooling capacity in the refrigerant pump cycle is exhibited. Means that no further cooling effect can be expected. Therefore, it is understood that switching the operation to the compression cycle in such a case is effective for indoor cooling.

Further, in the air conditioner according to the third aspect, similarly, when an abnormality is detected in the refrigerant flow rate or the refrigerant pump in the refrigerant circuit, the operator switches from the refrigerant pump cycle to the compression cycle. Is provided.

This air conditioner switches the operation from the refrigerant pump cycle to the compression cycle based on the refrigerant flow rate or the abnormality of the refrigerant pump. Here, the abnormal flow rate is detected, for example, when the refrigerant pump fails or when cavitation occurs in the refrigerant pump. In such a case, switching the operation to the compression cycle makes it possible to avoid an inoperable situation due to a refrigerant pump failure, and to avoid a subsequent refrigerant pump failure due to cavitation.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the annual cooling type air conditioner according to the present invention includes a refrigerant pump 1, an expansion valve 9, an evaporator (indoor heat exchanger) 4, a compressor 5, and a condenser (outdoor heat exchanger) 8. It has a refrigerant circuit connected in order (counterclockwise in the figure). Of these, the refrigerant pump 1 and the compressor 5 do not normally operate at the same time. In the present embodiment, when the refrigerant pump 1 is in operation, the flow of the refrigerant in the refrigerant circuit is referred to as “refrigerant pump cycle”, and the same applies to the case where the compressor 5 is in operation. Will be referred to as the “compression cycle”.

In the refrigerant circuit, in addition to the above components, an inverter 2 for the refrigerant pump,
A refrigerant pump bypass valve 3 and a compressor inverter 6 and a compressor bypass valve 7 are provided as accessory equipment of the compressor 5, respectively. Further, a bypass valve 10 of the expansion valve is provided as an accessory to the expansion valve 9.

Further, the indoor blower 1 is located near the evaporator 4.
The indoor air blower 13 is connected to an indoor air blower air volume control device 14. Similarly, an outdoor blower 11 and an outdoor blower air volume control device 12 connected to the outdoor blower 11 are also provided near the condenser 8. In addition, the refrigerant circuit is provided with a controller (control device) 16 for controlling the operation of each of these devices, and the controller 16 is connected to an outside air temperature sensor 15.

The operation of the compression cycle and the refrigerant pump cycle in the annual cooling type air conditioner provided with the refrigerant circuit having the above configuration is as follows. First, when operating in the compression cycle, the refrigerant pump bypass valve 3 is opened, and the compressor bypass valve 7 and the bypass valve 10 of the expansion valve are closed.
The compression cycle operates as follows. The gas refrigerant is pressurized by the compressor 5 and sent to the condenser 8 as a high-temperature and high-pressure gas, where the refrigerant exchanges heat with outside air to liquefy the refrigerant. The liquid refrigerant is decompressed by the expansion valve 9 and reaches the evaporator 4.
By cooling the indoor air at, the refrigerant gasifies and returns to the compressor 5. Hereinafter, by repeating this cycle,
Indoor cooling is performed by releasing indoor heat to the atmosphere via the evaporator 4 and the condenser 8.

On the other hand, when operating in a refrigerant pump cycle, the refrigerant pump bypass valve 3 is closed, and the compressor bypass valve 7 and the expansion valve bypass valve 10 are opened. The refrigerant pump cycle operates as follows. The gas refrigerant leaving the evaporator 4 is sent to the condenser 8 as it is, cooled and liquefied by low-temperature outside air in the condenser 8, and sent to the refrigerant pump 1. In the refrigerant pump 1, the liquid refrigerant is pressurized and guided to the evaporator 4. In the evaporator 4, the refrigerant is gasified by cooling the room air, and returns to the condenser 8 again. Hereinafter, this cycle is repeated, and the indoor heat is released to the atmosphere through the evaporator 4 and the condenser 8 to cool the indoor air.

The present invention is characterized in that both the compression cycle and the refrigerant pump cycle are switched according to the following criteria. FIG. 2 is a flowchart relating to the determination of switching from the compression cycle to the refrigerant pump cycle. That is, FIG. 2 assumes that the refrigerant pump cycle is in operation, and each step shows various criteria for switching from the refrigerant pump cycle to the compression cycle. First, as step S1, the outside air temperature is detected, and when the temperature becomes equal to or higher than a set value or rises to or above the set value, the operation is switched from the refrigerant pump cycle to the compression cycle. Here, it is needless to say that the measurement of the outside air temperature is performed by the outside air temperature sensor 15 and the determination regarding the set value is performed by the controller 16. Incidentally, such a method based on the outside air temperature can be said to be the simplest method for switching from the compression cycle to the refrigerant pump cycle.

Next, in step S2, it is determined whether or not the outdoor air blowing amount is maximum. If not, the process returns to step S1. If it is the maximum, the process proceeds to the next step S3. At this time, the “outdoor outdoor airflow amount maximum” is specifically, as a cooling capacity that can be exhibited in the refrigerant pump cycle operation, the rotation amount of the outdoor air blower 11 when the maximum value is achieved. Refers to That is, when the process proceeds to step S3 in step S2, the operation at the maximum cooling capacity of the refrigerant pump cycle is being performed.

In step S3, the room temperature is measured, and based on the result, it is determined whether or not the room temperature is equal to or higher than a predetermined set value. If it is not less than the set value, the operation is switched to the compression cycle, and if not, the process proceeds to the next step S4. The meaning of step S3 is as follows. That is, step S
That the determination according to No. 3 is performed means that the refrigerant pump cycle is currently being operated at the maximum cooling capacity, as described above. If the room temperature is higher than a certain set value in spite of this state, if the room temperature is left unchecked, the indoor environment may be deteriorated. That is, since the operation is being performed at the maximum cooling capacity at this time, it is not possible to expect a further cooling effect for the room. Therefore, in such a case, the operation is switched from the refrigerant pump cycle to the compression cycle. As a result, the indoor environment is properly maintained.

In step S3, the room temperature may be monitored for a certain period of time instead of performing the determination immediately. That is, the operation with the maximum cooling capacity in the refrigerant pump cycle may be performed for a while, and if the room temperature still does not fall below the set value, the operation may be switched to the compression cycle for the first time.

In step S4, it is determined whether or not the measured flow rate of the refrigerant flowing through the refrigerant circuit is equal to or greater than a set value. That is, it is determined whether the refrigerant flow rate is normal or abnormal. If it is determined that the operation is abnormal, the operation is switched from the refrigerant pump cycle to the compression cycle. If no flow rate abnormality is detected, the flow returns to step S1, and the above-described various determinations are performed again. Incidentally, this flow rate check is performed by the flow meter M shown in FIG.

By the way, the abnormality of the refrigerant flow rate mentioned above is specifically as described below. For example, it is directly due to the failure of the refrigerant pump 1.
In such a case, it is apparent that the flow rate of the refrigerant in the refrigerant circuit immediately becomes abnormal. Also, when cavitation occurs in the refrigerant pump 1, a steady flow of the refrigerant is no longer realized, and an abnormality in the flow rate will be seen. In this case, the refrigerant pump 1
Therefore, it is preferable to immediately stop the operation by the refrigerant pump cycle since it is expected that the failure will occur successively.

In step S4, in the above case,
The operation is switched from the refrigerant pump cycle to the compression cycle. In other words, for example, if the refrigerant pump 1 in the above example fails, it is no longer possible to carry out the operation by the refrigerant pump cycle, so that the operation immediately shifts to the compression cycle without leaving such a situation. Then, the indoor cooling will be continued. Further, when cavitation occurs, the process shifts to the compression cycle and the appropriate cooling operation is continued before the malfunction such as the failure of the refrigerant pump 1 is caused.

As described above, in the air conditioner according to the present embodiment, the switching from the refrigerant pump cycle to the compression cycle depends on the outside air temperature, the amount of air blown by the outdoor blower 11,
In addition, the determination is made based on the flow rates of the refrigerant in the refrigerant circuit, and the switching is performed under appropriate conditions.

In the above embodiment, the measurement / judgment relating to the outside air temperature (step S1), the measurement / judgment of the outdoor air flow rate (step S2), the measurement / determination relating to the indoor temperature
The determination (step S3) and the measurement and determination of the refrigerant flow rate (step S4) are performed in the same flow, but the present invention is not limited to such a form. That is, for example, in the above embodiment,
The measurement / judgment according to steps S2 and S3 may be performed, and the measurement / judgment according to step S4 may be omitted.

FIG. 3 illustrates the above situation.
In FIG. 3, the operation switching from the refrigerant pump cycle to the compression cycle is performed by independent routes R1, R2, and R3. Route R1 is
The outside air temperature "only" is used as a criterion, and when the temperature is equal to or less than a set value, the operation is switched to a compression cycle (step U1). In other words, FIG. 2 shows a case where only step S1 is performed alone. By the way,
In FIG. 3, the set value of the outside air temperature is 18 ° C.
Specific numerical values are shown. In the route R2, the operation is switched to the compression cycle by judging whether or not the indoor temperature is equal to or higher than the set value and whether or not the outdoor air blowing amount is maximum (Step V1). That is, in FIG. 2, it can be seen that steps S2 and S3 are performed. Further, the route R3 is based on whether or not there is a refrigerant flow rate abnormality (step W1). In this case, step S4 alone in FIG. 2 is performed. Thus, in FIG. 3, the route R1,
R2 and R3 will be implemented independently of each other.
However, in some cases, each route R1, R2, and R
3 may be incorporated in the controller 16 as software so that the selection can be made.

In any case, FIGS. 2 and 3
The above embodiment as shown in FIG.
All of these are within the concept of the present invention, such as the independent implementation of Steps 2 and S3, and the implementation of Step S4 alone.

[0029]

As described above, the air conditioner according to the first aspect switches the operation from the refrigerant pump cycle to the compression cycle based on the outside air temperature, so that when the outside air temperature becomes sufficiently high. Since the cooling capacity of the refrigerant pump is reduced, a compression cycle operation with a high cooling capacity is performed in that case.According to the air conditioner of the present invention, an advantageous operation from the viewpoint of indoor cooling efficiency is performed. Can be implemented.

The air conditioner according to the second aspect of the present invention provides a criterion for determining the operation switching between the two cycles, that is, a criterion that the outdoor air flow rate is maximum and the indoor temperature is equal to or higher than a set value. It can be seen that the operation switching is performed in a situation where a cooling effect cannot be expected, which is effective for indoor cooling.

Furthermore, in the air conditioner according to the third aspect of the present invention, similarly, since the refrigerant flow rate in the refrigerant circuit is provided as a criterion, it is possible to avoid an inoperable state due to a failure of the refrigerant pump, that is, to perform no cooling. Avoidance of things,
Further, it is possible to avoid the occurrence of a subsequent refrigerant pump failure due to the occurrence of cavitation.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a refrigerant circuit configuration of an air conditioner according to the present invention.

FIG. 2 is an operation flowchart of the air conditioner according to the present invention.

FIG. 3 is an operation flowchart in which one or more of the steps shown in FIG. 2 are independently performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigerant pump 2 Refrigerant pump inverter 3 Refrigerant pump bypass valve 4 Evaporator (indoor heat exchanger) 5 Compressor 6 Compressor inverter 7 Compressor bypass valve 8 Condenser (outdoor heat exchanger) 9 Expansion valve 10 Expansion valve 11 Outdoor air blower 12 Outdoor air blower air flow control device 13 Indoor air blower 14 Indoor air flow control device 15 Outside air temperature sensor 16 Controller

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigenori Waratani 3-4-1, Shibaura, Minato-ku, Tokyo F-term in NTT Facilities Corporation (reference) 3L060 AA03 CC03 DD02 DD07 EE02

Claims (3)

[Claims] 1. A refrigerant circuit in which a refrigerant pump, an expansion valve, an indoor heat exchanger, a compressor, and an outdoor heat exchanger are sequentially connected. In the refrigerant circuit, the refrigerant pump is operated to cool the room. An air conditioner capable of realizing a refrigerant pump cycle and a compression cycle in which the compressor is operated to cool a room, wherein when the outside air temperature is equal to or higher than a set value, the refrigerant pump cycle is switched to the compression cycle. An air conditioner comprising a control device for switching operation. 2. A refrigerant circuit in which a refrigerant pump, an expansion valve, an indoor heat exchanger, a compressor, and an outdoor heat exchanger are sequentially connected. In the refrigerant circuit, the refrigerant pump is operated to cool the room. A refrigerant pump cycle and an air conditioner capable of realizing a compression cycle of operating the compressor to cool the interior of the room, wherein the amount of air blown by an outdoor blower attached to the outdoor heat exchanger is maximum, and An air conditioner comprising: a control device that switches operation from the refrigerant pump cycle to the compression cycle when the room temperature is equal to or higher than a set value. 3. A refrigerant circuit in which a refrigerant pump, an expansion valve, an indoor heat exchanger, a compressor, and an outdoor heat exchanger are sequentially connected. In the refrigerant circuit, the refrigerant pump is operated to cool the room. An air conditioner capable of realizing a refrigerant pump cycle and a compression cycle of operating the compressor to cool the room, and when an abnormality is detected in the refrigerant flow rate or the refrigerant pump in the refrigerant circuit, An air conditioner, comprising: a control device that switches operation from the refrigerant pump cycle to the compression cycle.