JP2003004315A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overheat of a compressor and avoid wet vapor suction to the compressor. SOLUTION: A double pipe type heat exchanger 4 having an outside passage 4d and an inside passage 4c to exchange heat between refrigerants flowing through the passages are provided between an outdoor side heat exchanger 3 and an indoor side heat exchanger 6. The refrigerant vaporized in the indoor side heat exchanger 6 is cooled in the double pipe type heat exchanger 4 to be partially liquefied and returned to the compressor 1. The compressor is prevented from being overheated by vaporization in the compressor 1, and further, if excessive refrigerant is returned to the compressor 1, a three-way valve 7 is switched to return the refrigerant via a bypass pipe 17 without cooling the refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to cooling a refrigerant flowing back to a compressor to prevent overheating of the compressor and a so-called liquid back phenomenon to the compressor. It relates to a configuration for preventing.

[0002]

2. Description of the Related Art A conventional refrigerant circuit of an air conditioner has, for example, a compressor 30 and an outdoor heat exchanger 3 as shown in FIG.
1, the expansion valve 33, the indoor heat exchanger 32, and the accumulator 37 are sequentially connected, while the outdoor heat exchanger 31 is connected.
A capillary tube 34 is connected between a pipe connecting the expansion valve 33 and the expansion valve 33 and a pipe connecting the indoor heat exchanger 32 and the compressor 30. The capillary tube 34 brings the heated portion 34a into contact with a pipe connecting the compressor 30 and the outdoor heat exchanger 31,
The high-temperature refrigerant discharged from heats the liquid-phase refrigerant flowing in the capillary tube 34 to separate it into a liquid-phase state and a vapor-phase state.

The high-temperature and high-pressure refrigerant discharged from the compressor 30 flows into the outdoor heat exchanger 31 and releases heat to be condensed and liquefied. The condensed and liquefied refrigerant becomes a low temperature and low pressure through the expansion valve 33 and flows into the indoor heat exchanger 32,
It absorbs heat from the surroundings and evaporates and vaporizes. The evaporated and vaporized refrigerant is returned to the compressor 30 via the accumulator 37 in a vapor phase state. The liquid-phase refrigerant that has flowed into the capillary tube 34 from the outdoor heat exchanger 31 is heated in the heated portion 34a and partially evaporated and vaporized, while part of the compressor 30 remains in the liquid phase state.
The compressor 30 is cooled by evaporating and evaporating the refrigerant in the liquid phase in which the compressor 30 is prevented from being heated.

However, in the separation of the refrigerant into the liquid phase and the gas phase by heating in the heated portion 34a, the ratio of the separation into the liquid phase and the gas phase is not constant due to the influence of the outside temperature, etc. If an excessive amount of refrigerant in the liquid phase flows into the compressor 30, a so-called liquid back phenomenon may occur, and the compressor 30 may be damaged.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention accurately controls the temperature of the refrigerant flowing back to the compressor,
An object of the present invention is to provide an air conditioner capable of preventing overheating of a compressor and a liquid back phenomenon.

[0006]

In order to solve the above-mentioned problems, the present invention connects the discharge side of the compressor to the first port of the four-way valve and the suction side to the fourth port of the four-way valve. The second port of the valve is connected to one side of the outdoor heat exchanger, the other side of the outdoor heat exchanger is connected to the first connection port provided in the outer flow path of the double pipe heat exchanger, The second connection port provided in the outer flow path is connected to one side of the indoor heat exchanger via an expansion valve, and the other side of the indoor heat exchanger is connected to the inner flow of the double-tube heat exchanger. Connecting to a third connection port provided in the passage, connecting a fourth connection port provided in the inner flow path to the third port of the four-way valve, and connecting the other side of the indoor heat exchanger to the double port. Between a pipe connecting the third connection port of the pipe heat exchanger, and a pipe connecting the fourth connection port of the double pipe heat exchanger and the second port of the four-way valve A three-way switching valve is provided at the connection between the bypass pipe and the pipe connecting the other side of the indoor heat exchanger and the third connection port of the double-pipe heat exchanger together with the bypass pipe. The first port of the switching valve is connected to the indoor heat exchanger side, the second port is connected to the third connection port side of the double pipe heat exchanger, and the third port is connected to the bypass pipe. During the cooling operation, the first port and the second port of the four-way valve are communicated with the third port and the fourth port, respectively, and the first port and the second port of the three-way switching valve are connected. Communicating with the port, the refrigerant discharged from the compressor flows into the outdoor heat exchanger through the four-way valve, condenses to a low temperature, and passes through the outer flow path of the double-tube heat exchanger. It flows into the indoor heat exchanger, evaporates and vaporizes to a high temperature, and the double tube heat The refrigerant flows into the inside flow path of the exchanger and is cooled by exchanging heat with the low temperature refrigerant flowing through the outside flow path. It is designed to prevent overheating.

When the liquid-phase refrigerant flowing back to the compressor becomes excessive, the first port and the third port of the three-way switching valve are shut off by shutting off the first port and the second port. By communicating with the port, the refrigerant sent from the other side of the indoor heat exchanger is returned to the compressor through the bypass pipe.

Further, the three-way switching valve is provided in a pipe connected to the indoor heat exchanger, and is switched based on a detection value of a temperature sensor for detecting the temperature of the refrigerant.

Further, when the detected value of the temperature sensor reaches the saturation temperature at which the refrigerant transits from the liquid phase state to the gas phase state, the first port and the second port of the three-way switching valve are communicated with each other. The refrigerant sent from the other side of the indoor heat exchanger flows into the double-pipe heat exchanger.

Further, during the heating operation, the first port and the third port of the four-way valve are communicated with the second port and the fourth port, respectively, and the first port of the three-way switching valve is connected. And the third port are communicated with each other, and the refrigerant discharged from the compressor flows from the four-way valve through the bypass pipe into the indoor heat exchanger.

The discharge side of the compressor is connected to the first port of the four-way valve, and the suction side is connected to the fourth port of the four-way valve.
The second port of the four-way valve is connected to one side of the outdoor heat exchanger, and the other side of the outdoor heat exchanger is connected to the first connection port provided in the outer flow path of the double pipe heat exchanger. Then, the second connection port provided in the outer flow path is connected to one side of the indoor heat exchanger via an expansion valve, and the other side of the indoor heat exchanger is connected to the double tube heat exchanger. Connected to the third connection port provided in the inner flow path, the fourth connection port provided in the inner flow path is connected to the third port of the four-way valve, the other side of the indoor heat exchanger and the A pipe connecting the third connection port of the double-pipe heat exchanger, and a bypass pipe between the pipe connecting the fourth connection port of the double-pipe heat exchanger and the second port of the four-way valve. A pipe that connects the first electromagnetic on-off valve to the bypass pipe and connects the other side of the indoor heat exchanger of the bypass pipe to the third connection port of the double-pipe heat exchanger. A second electromagnetic on-off valve is provided between the connection portion and the third connection port of the double-tube heat exchanger, and during cooling operation, the first port and the second port of the four-way valve. And, while communicating the third port and the fourth port, respectively, to communicate the first port and the second port of the three-way switching valve, while closing the first solenoid on-off valve, the first (2) The electromagnetic on-off valve is opened, and the refrigerant discharged from the compressor flows into the outdoor heat exchanger via the four-way valve, condenses to a low temperature, and the outer flow path of the double-tube heat exchanger Flow into the indoor side heat exchanger, evaporate and vaporize to a high temperature, flow into the inner flow path of the double-tube heat exchanger, and exchange heat with a low temperature refrigerant flowing through the outer flow path to cool. Then, part of it becomes a liquid-phase refrigerant, returns to the compressor, evaporates, and overheats the compressor. And it has a configuration to prevent.

Further, when the liquid-phase refrigerant flowing back to the compressor becomes excessive, the second electromagnetic opening / closing valve is closed and the first electromagnetic opening / closing valve is opened, so that the indoor heat exchanger The refrigerant sent from the side is returned to the compressor through the bypass pipe.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail as examples based on the accompanying drawings. Figure 1
(A) is a refrigerant circuit diagram showing a first embodiment of an air conditioner according to the present invention, and FIG. 1 (B) is a sectional view showing a double-tube heat exchanger provided in the refrigerant circuit. FIG. 2A is a refrigerant circuit diagram showing the flow of the refrigerant during the cooling operation.
(B) is a refrigerant circuit diagram showing the flow of the refrigerant when the three-way switching valve described later is switched. 3 (A) is a refrigerant circuit diagram showing the flow of the refrigerant during heating operation, and FIG. 3 (B) is a refrigerant circuit diagram showing the second embodiment. The refrigerant circuit of the air conditioner according to the present invention, as shown in FIG.
The discharge side of the first pipe 9 to the first port 2a of the four-way valve 2,
The suction side is connected to the fourth port 2d of the four-way valve 2 by the eighth pipe 16 via the accumulator 8, and the second port 2b of the four-way valve 2 is connected by the second pipe 10 to the outdoor heat exchanger 3
Is connected to one side. The other side of the outdoor heat exchanger 3 is connected to the first pipe 4e of the double-pipe heat exchanger 4 by the third pipe 11.
And the second connection port 4f of the double-tube heat exchanger 4 connected to
Is connected to one side of the indoor heat exchanger 6 by a fourth pipe 12 having an expansion valve 5. The other side of the indoor heat exchanger 6 is connected to the first port 7a of the three-way switching valve 7 by the fifth pipe 13.
The second port 7b of the three-way switching valve 7 is connected to the third connection port 4g of the double pipe heat exchanger 4 by the sixth pipe 14.
It is connected to the. The fourth connection port 4h of the double-tube heat exchanger 4 is connected to the four-way valve 2 by a seventh pipe 15. Further, a bypass pipe 17 leading to the third port 7c of the three-way switching valve 7 is connected to the seventh pipe 15.

The three-way switching valve 7 is normally set so that the first port 7a and the second port 7b communicate with each other, and the switching operation allows the first port 7a and the second port 7b to communicate with each other. The first port 7a and the third port 7c are communicated with each other while blocking the space between them.

As shown in FIG. 1B, the double pipe heat exchanger 4 has the third connection port 4g and the fourth connection port 4h.
And a cylindrical inner tube 4a having both ends provided with
The first connection port 4e is formed so as to enclose the outer peripheral surface of a.
And a cylindrical outer pipe 4b provided with the second connection port 4f at both ends thereof, and the inner flow passage 4c is provided in the inner pipe 4a.
The outer flow path 4d between the outer pipe 4b and the inner pipe 4a.
Are formed respectively, and the refrigerant flowing through the inner flow passage 4c and the outer flow passage 4d exchanges heat.

Further, a temperature sensor 18 for detecting the temperature of the refrigerant is provided near the connection port of the pipe 13 with the indoor heat exchanger 6, and the detected value detected by the temperature sensor 18 is a control unit. 21 and the control section 21 switches the three-way switching valve 7.

Next, the flow of the refrigerant in the above-mentioned refrigerant circuit will be described. During operation of the refrigerant, the first port 2a and the second port 2b of the four-way valve 2 are connected to the third port 2
c and the fourth port 2d communicate with each other, and the three-way switching valve 7 communicates with the first port 7a and the second port 7b as described above, and the first port 7a and the third port. 7c is cut off.
The high-temperature high-pressure refrigerant discharged from the discharge side of the compressor 1 is transferred to the outdoor heat exchanger 3 via the four-way valve 2 and the second pipe 10 as shown in FIG. 2 (A). Inflow,
The heat is released from the outdoor heat exchanger 3 in the same room to be condensed and liquefied to become a low-temperature refrigerant which flows from the first connection port 4e of the double-tube heat exchanger 4 into the outer flow path 4d. Same outside flow path 4d
The refrigerant flowing through the second connection port 4f is decompressed by the expansion valve 5 and flows into the indoor heat exchanger 6,
The indoor heat exchanger 6 absorbs ambient heat and evaporates and vaporizes. The evaporated high-temperature refrigerant passes through the fifth pipe 13 from the first port 7a of the three-way switching valve 7 to the second port 7b, and from the third connection port 4g to the double pipe heat exchange. It flows into the inner flow path 4c of the container 4. The high-temperature vapor-phase refrigerant that has flowed into the inner flow passage 4c is transferred to the outer flow passage 4c.
It is cooled by exchanging heat with the low-temperature liquid-phase refrigerant flowing through d, and a part of it is in a liquid-phase state. The refrigerant in the liquid phase is mixed with the refrigerant in the gas phase, flows through the seventh pipe 15 and flows back to the compressor 1 through the four-way valve 2, and evaporates and vaporizes in the compressor 1. The compressor 1 is cooled to prevent its overheating.

However, when an excessive amount of liquid-phase refrigerant flows into the compressor 1, there is a risk of damage to the inside of the compressor 1. In order to prevent such a situation, the indoor heat exchanger 6 is prevented. When the detection value of the temperature sensor 18 provided in the vicinity is lower than the set reference value, the three-way switching valve 7 is switched to the first port 7a and the second port 7
The first port 7a and the third port 7c are made to communicate with each other while blocking the connection with b. As a result, as shown in FIG. 2B, the indoor heat exchanger 6 is
The refrigerant flowing out from the three-way switching valve 7 passes from the first port 7a through the third port 7c to the bypass pipe 17
To the compressor 1 through the seventh pipe 15 and the four-way valve 2 without passing through the double pipe heat exchanger 4.

When the value detected by the temperature sensor 18 reaches the saturation temperature at which the refrigerant changes from the liquid phase state to the gas phase state,
The first port 7a and the second port b of the three-way switching valve 7 are communicated with each other again, and the refrigerant sent from the indoor heat exchanger 6 flows into the double-pipe heat exchanger 4, The refrigerant exchanges heat with the refrigerant flowing through the outer flow path 4d, is cooled, and is returned to the compressor 1.

Next, the flow of the refrigerant during the heating operation will be described. During the heating operation, the four-way valve 2 is switched so that the first port 2a and the third port 2c communicate with each other and the third port 2b and the fourth port 2d communicate with each other,
The three-way switching valve 7 blocks the first port 7a and the second port 7b while the first port 7a and the third port 7c communicate with each other.
The high-temperature and high-pressure refrigerant discharged from the discharge side of the compressor 1 flows into the bypass pipe 17 from the seventh pipe 15 via the four-way valve 2 as shown in FIG. 3, and the three-way switching valve 7 From the third port 7c through the first port 7a to flow into the indoor heat exchanger 6. The refrigerant flowing into the indoor heat exchanger 6 releases heat and condenses, and the outdoor heat exchanger 3 passes through the expansion valve 5 and the outer flow path 4d of the double-pipe heat exchanger 4. And is absorbed in the outdoor heat exchanger 3 to evaporate. The evaporated refrigerant recirculates to the compressor 1 via the four-way valve 2.

Next, a second embodiment will be shown. In the example shown in FIG. 3B, the bypass pipe 17 is provided with a first electromagnetic opening / closing valve 19,
A second electromagnetic on-off valve 20 is provided in each of the sixth pipes 14, the first electromagnetic on-off valve 19 is closed, the second electromagnetic on-off valve 20 is opened, and flows out from the indoor heat exchanger 6 during a cooling operation. When the refrigerant that has been cooled passes through the double-pipe heat exchanger 4 and returns to the compressor 1, while excess liquid-phase refrigerant may return to the compressor 1, the second electromagnetic switching By closing the valve 20 and opening the first electromagnetic opening / closing valve 19, the refrigerant flowing out of the indoor heat exchanger 6 flows back to the compressor 1 through the bypass pipe 17. In addition, during the heating operation, the first electromagnetic on-off valve 19 is opened and the second electromagnetic on-off valve 20 is closed to perform the operation. By using a pair of electromagnetic on-off valves, the cost can be reduced. Reductions are being made.

[0022]

As described above, according to the present invention,
Between the outdoor heat exchanger and the indoor heat exchanger, an outer flow passage and an inner flow passage are provided, and a double-pipe heat exchanger for exchanging heat between the refrigerants flowing through these is provided, and the indoor side is provided. Refrigerant evaporatively vaporized in the heat exchanger is cooled in the double-tube heat exchanger to liquefy a part of the refrigerant and recirculate to the compressor to evaporate and vaporize in the compressor to prevent overheating of the compressor. When excess liquid-phase refrigerant is returned to the compressor, the refrigerant is cooled by switching the three-way switching valve provided between the indoor heat exchanger and the double-tube heat exchanger. It is possible to provide an air conditioner with improved reliability that can prevent a so-called liquid back phenomenon by allowing the air to flow back to the compressor via a bypass pipe instead.

[Brief description of drawings]

FIG. 1A is a refrigerant circuit diagram showing a first embodiment of an air conditioner according to the present invention. (B) is a cross-sectional view showing a double-tube heat exchanger provided in the air conditioner according to the present invention.

FIG. 2A is a refrigerant circuit diagram showing a refrigerant flow during a cooling operation. (B) is a refrigerant circuit diagram showing a refrigerant flow when the three-way selector valve is switched during the cooling operation.

FIG. 3A is a refrigerant circuit diagram showing a refrigerant flow during heating operation. (B) is a refrigerant circuit diagram showing a second embodiment.

FIG. 4 is a refrigerant circuit diagram showing an example of a conventional air conditioner.

[Explanation of symbols]

1 compressor 2 four-way valve 2a First port 2b Second port 2c Third port 2d 4th port 3 Outdoor heat exchanger 4 Double tube heat exchanger 4a inner tube 4b outer tube 4c inner channel 4d outer channel 4e First connection port 4f Second connection port 4g Third connection port 4h Fourth connection port 5 expansion valve 6 Indoor heat exchanger 7 three-way switching valve 7a First port 7b Second port 7c Third port 8 Accumulator 9 First piping 10 Second piping 11 Third piping 12 Fourth piping 13 Fifth piping 14 sixth piping 15 Seventh piping 16 eighth pipe 17 Bypass pipe 18 Temperature sensor 19 First solenoid on-off valve 20 Second solenoid on-off valve 21 Control unit

Claims (7)

[Claims] 1. The discharge side of the compressor is connected to the first port of the four-way valve, and the suction side is connected to the fourth port of the four-way valve, and the second port of the four-way valve is connected to one side of the outdoor heat exchanger. Connected to the other side of the same room outside heat exchanger to the first connection port provided in the outer flow path of the double-tube heat exchanger, the second connection port provided in the outer flow path is expanded. Connected to one side of the indoor heat exchanger via a valve, and connect the other side of the indoor heat exchanger to a third connection port provided in the inner flow path of the double-pipe heat exchanger, A pipe connecting the fourth connection port provided in the inner flow path to the third port of the four-way valve, and connecting the other side of the indoor heat exchanger and the third connection port of the double-pipe heat exchanger. A bypass pipe is provided between a pipe connecting the fourth connection port of the double-pipe heat exchanger and the second port of the four-way valve, and the bypass pipe, and A three-way switching valve is provided at the connection between the other side of the indoor heat exchanger and the pipe connecting the third connection port of the double-pipe heat exchanger, and the first port of the three-way switching valve is used for the indoor heat exchange. The second port is connected to the third pipe, the second port is connected to the third connection port side of the double-pipe heat exchanger, and the third port is connected to the bypass pipe. During cooling operation, the first port of the four-way valve is connected. The port and the second port are communicated with the third port and the fourth port, respectively, and the first port and the second port of the three-way switching valve are communicated with each other, and discharged from the compressor. Refrigerant flows into the outdoor heat exchanger through the four-way valve, condenses to a low temperature, flows into the indoor heat exchanger through the outer flow path of the double-tube heat exchanger, and evaporates. Becomes high temperature and flows into the inner flow path of the double pipe heat exchanger, and flows through the outer flow path. An air conditioner which is cooled by exchanging heat with a low-temperature refrigerant, and part of which becomes a liquid-phase refrigerant to flow back to the compressor and evaporate to prevent overheating of the compressor. 2. When the liquid-phase refrigerant flowing back to the compressor becomes excessive, the three-way switching valve is shut off between the first port and the second port, and the first port and the third port are shut off. The air conditioner according to claim 1, wherein the refrigerant sent from the other side of the indoor heat exchanger is returned to the compressor through the bypass pipe by communicating with the port. Machine. 3. The three-way switching valve is provided in a pipe connected to the indoor heat exchanger, and is switched based on a detection value of a temperature sensor that detects the temperature of the refrigerant. The air conditioner according to Item 1. 4. When the detected value of the temperature sensor reaches a saturation temperature at which the refrigerant transits from a liquid phase state to a gas phase state, the first port and the second port of the three-way switching valve are communicated with each other. The air conditioner according to claim 2, wherein the refrigerant sent from the other side of the indoor heat exchanger is allowed to flow into the double-pipe heat exchanger. 5. During heating operation, the first port and the third port of the four-way valve are communicated with the second port and the fourth port, respectively, and the first port of the three-way switching valve is connected. And the third port are communicated with each other, and the refrigerant discharged from the compressor flows into the indoor heat exchanger through the bypass pipe from the four-way valve. Air conditioner 6. The discharge side of the compressor is connected to the first port of the four-way valve, the suction side is connected to the fourth port of the four-way valve, and the second port of the four-way valve is connected to one side of the outdoor heat exchanger. Connected to the other side of the same room outside heat exchanger to the first connection port provided in the outer flow path of the double-tube heat exchanger, the second connection port provided in the outer flow path is expanded. Connected to one side of the indoor heat exchanger via a valve, and connect the other side of the indoor heat exchanger to a third connection port provided in the inner flow path of the double-pipe heat exchanger, A pipe connecting the fourth connection port provided in the inner flow path to the third port of the four-way valve, and connecting the other side of the indoor heat exchanger and the third connection port of the double-pipe heat exchanger. A bypass pipe is provided between a pipe connecting the fourth connection port of the double-pipe heat exchanger and the second port of the four-way valve, and the bypass pipe has a first electrical connection. A magnetic on-off valve, a connecting portion of a pipe connecting the other side of the indoor heat exchanger of the bypass pipe and a third connection port of the double-pipe heat exchanger, and the double-pipe heat exchanger A second electromagnetic on-off valve is provided between the third connection port and the third connection port, respectively, during cooling operation, the first port and the second port of the four-way valve, the third port and the fourth port While communicating with each other, the first port and the second port of the three-way switching valve are communicated with each other, the first electromagnetic on-off valve is closed, while the second electromagnetic on-off valve is opened, and discharged from the compressor. Refrigerant flows into the outdoor heat exchanger through the four-way valve, condenses to a low temperature, flows into the indoor heat exchanger through the outer flow path of the double-tube heat exchanger, and evaporates. Become high temperature and flow into the inner flow path of the double-tube heat exchanger and flow through the outer flow path. Is cooled by the refrigerant heat exchange with hot, partially air conditioner characterized by comprising to prevent overheating refluxed to the compressor becomes a liquid phase refrigerant evaporated in the compressor. 7. When the liquid-phase refrigerant flowing back to the compressor becomes excessive, the second electromagnetic on-off valve is closed and the first electromagnetic on-off valve is opened, so that the indoor heat exchanger The air conditioner, wherein the refrigerant sent from the side is returned to the compressor through the bypass pipe.