JP3995824B2 - air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner for high heat generation equipment that requires cooling even when the outside air temperature is low, and in particular, has a refrigerant pump that actively cools the room by utilizing the low outside air temperature. It relates to annual cooling type air conditioners.
[0002]
[Prior art]
In general, as an indoor cooling method, there is an air conditioner using a compression refrigeration cycle. The cooling principle of the 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, and the refrigerant liquefies by exchanging heat with the outside air. The liquid refrigerant is decompressed by the expansion valve and enters the evaporator, or the indoor air is cooled in the evaporator, whereby the refrigerant gasifies and returns to the compressor. Hereinafter, by repeating this cycle, indoor heat is released by releasing indoor heat into the atmosphere through an evaporator and a condenser.
[0003]
When the outside air temperature is low, the cooling operation can be performed only by circulating the refrigerant with the refrigerant pump without operating the compressor. This method is called indirect outdoor air cooling because the refrigerant is once cooled with outside air and the indoor cooling is performed with the cooled refrigerant. In some cases, water is used as a circulation medium. However, if a refrigerant is used, the phase change can be used. Therefore, the pump power can be reduced by reducing the circulation amount.
[0004]
The cooling cycle in indirect outside air cooling will be described below. The gas refrigerant exiting the evaporator is sent to the condenser as it is, cooled in the condenser with low temperature outside air, liquefied, and sent to the refrigerant pump. In the refrigerant pump, the liquid refrigerant is pressurized and guided to the evaporator. In the evaporator, the indoor air is cooled to gasify the refrigerant and return to the condenser again. Thereafter, this cycle is repeated to cool the room by releasing the indoor heat into the atmosphere through the evaporator and the condenser.
[0005]
[Problems to be solved by the invention]
In view of the above, it is efficient to operate in the compression cycle when the outside air temperature is high, and to operate in the refrigerant pump cycle when the outside air temperature is low. More specific criteria and switching operation methods such as valve operation when switching between the two cycles have not been determined.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to switch between both cycles in an air conditioner capable of realizing a refrigerant pump cycle and a compression cycle in a most suitable environment. An object of the present invention is to provide an air conditioner capable of operating a valve in a suitable refrigerant circuit at the time.
[0007]
[Means for Solving the Problems]
The present invention takes the following means in order to solve the above 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 connected in order, and the refrigerant pump is operated in the refrigerant circuit. An air conditioner capable of realizing a refrigerant pump cycle that performs indoor cooling and a compression cycle that operates the compressor to perform indoor cooling, and bypasses the refrigerant pump when switching between the two cycles. Each of the valve, the bypass valve of the expansion valve, and the bypass valve of the compressor is provided with a control device that performs a valve operation to be opened for a predetermined time.
[0008]
According to this air conditioner, when the operation is switched from the compression cycle to the refrigerant pump cycle and from the refrigerant pump cycle to the compression cycle, the bypass valves related to the compressor, the expansion valve, and the refrigerant pump are all opened. The refrigerant in the refrigerant circuit is in a naturally flowing state, and it is possible to achieve uniform refrigerant pressure in the indoor heat exchanger and the outdoor heat exchanger.
[0009]
An air conditioner according to claim 2 is an air conditioner having the same premise as the air conditioner according to claim 1, wherein the expansion valve is switched when operation is switched from the compression cycle to the refrigerant pump cycle. And a control device that performs a valve operation for closing the bypass valve of the refrigerant pump after a predetermined time has elapsed since the bypass valve of the compressor and the bypass valve of the compressor have been opened. Further, in the air conditioner according to claim 3, similarly, at the time of switching the operation from the refrigerant pump cycle to the compression cycle, after a predetermined time elapses after the bypass valve of the refrigerant pump is opened, the expansion valve A control device is provided that performs a valve operation for closing the bypass valve and the bypass valve of the compressor.
[0010]
These air conditioners implement | achieve the aspect which controls appropriately valve operation by the control apparatus in the air conditioner of Claim 1 according to each cycle transition. In other words, in any operation transition from the compression cycle to the refrigerant pump cycle and from the refrigerant pump cycle to the compression cycle, a situation where the three bypass valves are opened for a predetermined time in an appropriate state is displayed. Is possible.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described 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 refrigerant circuits that are connected in order (counterclockwise in the figure). Of these, the refrigerant pump 1 and the compressor 5 are not normally operated simultaneously. In the present embodiment, the refrigerant flow in the refrigerant circuit when the refrigerant pump 1 is in operation is indicated as “refrigerant pump cycle”, and the same applies when the compressor 5 is in operation. This is called the “compression cycle”.
[0012]
In the refrigerant circuit, in addition to the above-described components, the refrigerant pump inverter 2 and the refrigerant pump bypass valve 3 are attached to the refrigerant pump 1, and the compressor inverter 6 and the compressor bypass valve 7 are attached to the compressor 5. , Are provided. Further, an expansion valve bypass valve 10 is provided as an accessory of the expansion valve 9.
[0013]
Further, an indoor fan 13 is provided in the vicinity of the evaporator 4, and an indoor fan air volume control device 14 is connected to the fan 13. Similarly, an outdoor fan 11 and an outdoor fan air volume control device 12 connected to the outdoor fan 11 are also provided near the condenser 8. In addition, the refrigerant circuit is provided with a controller (control device) 16 for performing operation control of these devices, and an outside air temperature sensor 15 is connected to the controller 16.
[0014]
In the annual cooling type air conditioner including the refrigerant circuit having the above-described configuration, the operation of the compression cycle and the refrigerant pump cycle is as follows.
First, when operating in a compression cycle, the refrigerant pump bypass valve 3 is opened, and the compressor bypass valve 7 and the expansion valve bypass valve 10 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. The condenser 8 exchanges heat with the outside air and liquefies the refrigerant. The liquid refrigerant is decompressed by the expansion valve 9 and reaches the evaporator 4, and the refrigerant is gasified by cooling the indoor air in the evaporator 4 and returns to the compressor 5. Hereinafter, by repeating this cycle, indoor heat is released by releasing indoor heat into the atmosphere via the evaporator 4 and the condenser 8.
[0015]
On the other hand, when operating with 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 discharged from the evaporator 4 is sent to the condenser 8 as it is, cooled by the low-temperature outside air in the condenser 8 and liquefied, 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 indoor air and returns to the condenser 8 again. Thereafter, this cycle is repeated, and the indoor heat is released by releasing the indoor heat into the atmosphere through the evaporator 4 and the condenser 8.
[0016]
By the way, in the present invention, both the compression cycle and the refrigerant pump cycle described above are switched by valve operation as described below.
FIG. 2 is a flowchart regarding valve operation at the time of switching from the compression cycle to the refrigerant pump cycle. That is, the figure assumes that the compression cycle is being operated. First, as step S1, it is determined whether or not the operation of the compressor 5 is stopped. When the compressor 5 is not stopped, the process returns to step S1, and when it is stopped, the process proceeds to step S2. The stop of the compressor 5 referred to here is, for example, when the controller 16 switches from the compression cycle to the refrigerant pump cycle when the outside air temperature is determined to be lower than a predetermined set value by measuring the outside air temperature or the like. This means that the operation is stopped by first controlling the operation of the compressor 5 when switching the operation.
[0017]
Next, as steps S2 and S3, both the bypass valve 10 of the expansion valve and the compressor bypass valve 7 are opened. As a result, the refrigerant does not flow through the expansion valve 9 and the compressor 5. At this time, it should be noted that the refrigerant pump bypass valve 3 is still open. That is, the bypass valves 3, 7, and 10 provided in the refrigerant circuit of the present air conditioner are all open.
[0018]
In step S4, the three bypass valves 3, 7, and 10 are kept open and wait for a predetermined time until a predetermined time elapses. When the set time has elapsed, the process proceeds to step S5, and the refrigerant pump bypass valve 3 is closed. At this point, the refrigerant pump cycle is established as the refrigerant flow in the refrigerant circuit, and the operation by the cycle, that is, the operation of the refrigerant pump 1 is actually started (step S6).
[0019]
FIG. 3 is a flowchart regarding valve operation at the time of switching from the refrigerant pump cycle to the compression cycle. That is, in this case, contrary to FIG. 2, it is assumed that the refrigerant pump cycle is being operated. First, as Step U1, it is determined whether or not the operation of the refrigerant pump 1 is stopped. When refrigerant pump 1 has not stopped, it returns to Step U1 again, and when it has stopped, it progresses to Step U2. The stop of the refrigerant pump 1 here is an operation stop associated with cycle switching, and the determination (for example, the outside air temperature is equal to or higher than the set value) is made in advance before the operation stop in FIG. This is the same as the description related to step S1.
[0020]
Next, as step U2, the refrigerant pump bypass valve 3 is opened. As a result, the refrigerant does not flow into the refrigerant pump 1. Further, at this time, the three bypass valves 3, 7, and 10 are all open, as in steps S2 and S3 in FIG.
[0021]
Then, after waiting for the set time to elapse in step U3, in steps U4 and U5, both the bypass valve 10 of the expansion valve and the compressor bypass valve 7 are closed. At this point, the compression cycle is established as the flow of the refrigerant in the refrigerant circuit, and the operation of the cycle, that is, the operation of the compressor 5 is actually started (step U6).
[0022]
From the above description, it should be noted in FIGS. 2 and 3 that there is a state in which the three bypass valves 3, 7, and 10 are open at the time of cycle switching. In the refrigerant circuit, by performing such an operation, the refrigerant in the refrigerant circuit is in a natural flow state, and pressure equalization with respect to the evaporator 4 and the condenser 8 proceeds.
[0023]
To explain this in more detail, during the compression cycle operation, the refrigerant pressure in the condenser 8 shown in FIG. 1 becomes higher than that in the evaporator 4, and conversely during the refrigerant pump cycle operation, the condenser The refrigerant pressure at 8 is lower than that of the evaporator 4. For example, during the compression cycle operation, 9 kg / cm ² refrigerant pressure in the condenser 8, whereas it is 6 kg / cm ² in the evaporator 4, the condenser 8 at the time of the refrigerant pump cycle operation 5 kg / cm ^2, the evaporator 6 kg / cm ² and so on. Normally, the refrigerant pressure in the evaporator 4 is approximately equal in both cycles (both are 6 kg / cm ^{2 in the} above case), so when the cycle is switched, the pressure in the condenser 8 changes greatly (also from 9 kg / cm ² to 5 kg / cm ^2). Or 5 kg / cm ² to 9 kg / cm ² ). Therefore, when sudden cycle switching is performed, the compressor 5 and the refrigerant pump 1 are suddenly subjected to reverse pressure, which causes a problem in operation. Therefore, as described above, it is effective to achieve uniform refrigerant pressure with respect to the evaporator 4 and the condenser 8 by performing the valve operation so that the three bypass valves 3, 7, and 10 are simultaneously opened. I understand. In particular, at the time of operation transition from the compression cycle to the refrigerant pump cycle, if other conditions are prepared, after causing natural circulation in the refrigerant circuit, the refrigerant pump bypass valve 3 is closed (step S5 is performed). )
[0024]
As described above, according to the present air conditioner, the refrigerant in the refrigerant circuit, particularly the refrigerant relating to the evaporator 4 and the condenser 8 is switched when the operation is switched from the compression cycle to the refrigerant pump cycle and from the refrigerant pump cycle to the compression cycle. Since the uniform pressure is achieved, there is no sudden pressure change in the compressor 5 and the refrigerant pump 1, and there is no adverse effect on them. That is, in this embodiment, stable cycle switching can be performed.
[0025]
【The invention's effect】
As described above, in the air conditioner according to claim 1, since the bypass valves related to the compressor, the expansion valve, and the refrigerant pump are all open when switching between the two cycles, the refrigerant in the refrigerant circuit is It becomes a natural flow state and realizes uniform refrigerant pressure in the indoor heat exchanger and the outdoor heat exchanger. Therefore, the air conditioner according to the present invention can perform stable operation as a whole, including the cycle switching, without causing an excessive pressure change to the compressor and the refrigerant pump in the cycle switching.
[0026]
In the air conditioner according to claims 2 and 3, the valve operation corresponding to each case of operation switching from the compression cycle to the refrigerant pump cycle and operation switching from the refrigerant pump cycle to the compression cycle is performed. Therefore, the most appropriate control can be obtained, and naturally, the effect obtained by the air conditioner according to the first aspect can be enjoyed in the same manner.
[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 relating to operation switching from a compression cycle to a refrigerant pump cycle in the air conditioner of the present invention.
FIG. 3 is an operation flowchart relating to operation switching from the refrigerant pump cycle to the compression cycle in the air conditioner of the present invention.
[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)
DESCRIPTION OF SYMBOLS 9 Expansion valve 10 Bypass valve 11 of expansion valve Outdoor fan 12 Outdoor fan air volume control device 13 Indoor fan 14 Indoor fan air flow controller 15 Outside temperature sensor 16 Controller

Claims (3)

A refrigerant pump cycle in which a refrigerant pump, an expansion valve, an indoor heat exchanger, a compressor, and an outdoor heat exchanger are sequentially connected, and in the refrigerant circuit, the refrigerant pump is operated to cool the room; An air conditioner that can be operated by switching between a compression cycle that operates the compressor and cools the room indoors, and when the operation is switched between the two cycles, a bypass valve of the refrigerant pump, a bypass valve of the expansion valve, And the air conditioner characterized by including the control apparatus which performs valve operation so that all the bypass valves of the said compressor may be opened for predetermined time. 2. The air conditioner according to claim 1, wherein at the time of operation switching from the compression cycle to the refrigerant pump cycle, after a predetermined time elapses after the bypass valve of the expansion valve and the bypass valve of the compressor are opened, An air conditioner comprising a control device that performs a valve operation to close a bypass valve of a refrigerant pump. 2. The air conditioner according to claim 1, wherein when the operation is switched from the refrigerant pump cycle to the compression cycle, after a predetermined time has elapsed since the bypass valve of the refrigerant pump is opened, the bypass valve of the expansion valve and the An air conditioner comprising a control device that performs a valve operation to close a bypass valve of a compressor.

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