JPH06174313A - Air conditioner - Google Patents

Abstract

PURPOSE:To provide an air conditioner with a satisfactorily stable freezing cycle and with a stabilized performance. CONSTITUTION:In a freezing cycle where there are successively connected a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 4, and an indoor heat exchanger 5, a suction temperature sensor 12 is provided on a suction side of the compressor 1. The temperature sensor 12 detects overheating of the compressor 1 and liquid back to the same. There is further provided a bypass circuit 10 which serves to return upon overheating of the compressor 1 a refrigerant existent between the expansion valve 4 and the indoor heat exchanger 5 to the suction side of the compressor 1 and returns upon liquid back of the compressor 1 a refrigerant discharged from the compressor 1 to the suction side of the compressor 1.

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 an air conditioner in which a refrigeration cycle is provided with a bypass circuit for preventing overheating and liquid back of the compressor to improve the stability of the refrigeration cycle. .

[0002]

2. Description of the Related Art In this type of refrigeration cycle, a thermal type expansion valve or an electric expansion valve is used as an expansion valve, and its opening is controlled so that the refrigerant flow rate becomes appropriate according to the load of the refrigeration cycle. It

However, even if such an expansion valve such as a heat-sensitive expansion valve or an electric expansion valve is used, the discharge temperature tends to be overheated due to a sudden change in load or the like, and conversely, a liquid back is formed on the suction side. It will occur.

Therefore, conventionally, when the discharge becomes overheated, the liquid refrigerant is compressed through a condenser outlet and a bypass passage (injection circuit) provided on the compressor suction side in order to lower the temperature of the discharged refrigerant. I was trying to return to the suction side.

Further, when liquid back occurs, in order to lower the temperature of the suction refrigerant, the discharge refrigerant is passed through the bypass passage (release circuit) provided on the discharge side and the suction side of the compressor. I was going to return it to.

[0006]

However, in the conventional cycle, since each bypass circuit is provided independently, the refrigerating cycle itself becomes complicated and becomes a large size.

Further, when the defrosting system is a so-called bypass defrosting system in which the discharged refrigerant is directly introduced to the outdoor heat exchanger, the circuit is further added, so that the refrigeration cycle becomes more and more complicated.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, to cope with discharge refrigerant overheating and liquid back, and to perform bypass defrosting without making the refrigeration cycle complicated and large. To provide a harmony machine.

[0009]

To achieve the above object, the present invention provides a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger are connected in sequence,
A suction temperature sensor is installed on the suction side of the compressor.The temperature sensor detects overheating and liquid back of the compressor, and when the compressor overheats, the refrigerant between the expansion valve and the indoor heat exchanger is sucked into the compressor. And a bypass circuit for returning the refrigerant discharged from the compressor to the suction side of the compressor when the compressor is backed up, and also the compressor, the four-way valve, the outdoor heat exchanger, the expansion valve and the indoor In a refrigeration cycle in which heat exchangers are sequentially connected, a suction temperature sensor is provided on the suction side of the compressor, the discharge side of the compressor and the heating inlet side of the outdoor heat exchanger are connected by a defrost line, and the expansion valve And the indoor heat exchanger and the suction side of the compressor are connected by a bypass line, the defrosting line and the bypass line are connected by a bypass four-way valve, the refrigerant between the expansion valve and the indoor heat exchanger Return to the suction side of the compressor, and A bypass circuit that returns the refrigerant to the suction side of the compressor is formed, and an electronic control valve is connected to the bypass circuit on the downstream side of the bypass four-way valve, and the detection value of the suction temperature sensor is input and based on the detection value. A control device for switching the bypass four-way valve and controlling the opening degree of the electronic control valve is provided.

[0010]

According to the above construction, by connecting the injection circuit, the release circuit and the defrosting circuit by using the bypass four-way valve, respectively, the refrigeration cycle is simplified and the bypass defrosting is performed at the time of defrosting. When the compressor is overheated, the refrigerant between the expansion valve and the indoor heat exchanger is returned to the compressor via the bypass circuit to prevent it from overheating.
Further, at the time of liquid back, the liquid back can be prevented by returning the high temperature and high pressure refrigerant to the compressor through the bypass circuit.

Further, the suction temperature sensor controls the opening of the electronic control valve to control the amount of refrigerant flowing through the bypass circuit, thereby sufficiently responding to the transient temperature change at the time of starting the compressor to stabilize the cycle. I can drive.

[0012]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a refrigeration cycle of an air conditioner of the present invention, in which a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an electronically controlled expansion valve 4 and an indoor heat exchanger 5 are sequentially connected. A refrigeration cycle is constructed.

The discharge side of the compressor 1 and the heating inlet side 3a of the outdoor heat exchanger 3 are connected by a defrost line 6, and a two-way defrost valve 7 is connected to the defrost line 6. A bypass line 8 connects the expansion valve 4 and the indoor heat exchanger 5 to the suction side of the compressor 1. This defrost line 6 and bypass line 8
A bypass four-way valve 9 is connected to the bypass circuit 1
0 is formed. An electronic control valve 11 is connected to the bypass circuit 10 on the downstream side of the bypass four-way valve 9.

A suction temperature sensor 12 is attached to the suction side of the compressor 1, and the suction temperature sensor 12 is provided.
The detected value of is input to the control device 13. The control device 13 controls the opening degree of the expansion valve 4 so that the suction temperature becomes a constant value, determines whether the compressor 1 is in the overheated state or the liquid back state based on the detection value of the suction temperature sensor 12, and determines whether the overheated state is reached. At this time, while the bypass four-way valve 9 is OFF, the electronic control valve 11 is opened to control the opening thereof, and in the liquid back state, the bypass four-way valve 9 is operated (ON) and the port shown by the dotted line in the figure is shown. The switching is performed so as to connect the two, and the opening degree of the electronic control valve 11 is controlled.

Next, the operation of the embodiment will be described.

During the cooling operation, the high-temperature high-pressure refrigerant from the compressor 1 flows as shown by the solid line arrow. That is, the high-temperature high-pressure refrigerant from the compressor 1 flows through the four-way valve 2 to the outdoor heat exchanger 3, where it is heat-exchanged with outdoor air to be condensed, decompressed by the expansion valve 4 and flowed into the indoor heat exchanger 5. Then, the heat is exchanged with the room air to cool the room, and the refrigerant becomes an evaporative refrigerant and returns to the compressor 1 via the four-way valve 2.

During the heating operation, the four-way valve 2 is switched, and the refrigerant is caused to flow in the reverse cycle of the cooling operation, as indicated by the dotted line arrow in the figure. That is, the high temperature high pressure refrigerant from the compressor 1 is
After flowing through the four-way valve 2 to the indoor heat exchanger 5, where it is condensed to heat the room, the pressure is reduced by the expansion valve 4, evaporated by the outdoor heat exchanger 3, and returned to the compressor through the four-way valve 2. It becomes a flow.

Next, referring to Table 2, the control of the controller 13 will be described.

[0020]

[Table 1]

The control device 13 includes a suction temperature sensor 12
It is determined whether the compressor 1 is in the overheated state, the liquid back state, or the defrosting of the outdoor heat exchanger 3 during the heating operation is necessary based on the detection value of 1.

First, when the compressor 1 is overheated, the electronic control valve 11 is fully closed to fully opened while the defrosting two-way valve 7 is off and the bypass four-way valve 9 is off. Control according to the overheat condition. As a result, the refrigerant from the indoor heat exchanger 5 and the expansion valve 4 flows through the bypass four-way valve 9 to the bypass line 8 as shown by the white arrow in the figure,
After the amount of the refrigerant is controlled by the electronic control valve 11 so that the suction temperature becomes 5 to 7 ° C., for example, the refrigerant is combined with the evaporated refrigerant of the refrigeration cycle and enters the compressor 1 to prevent overheating there.

Next, the case where the compressor 1 is in the liquid back state will be described.

The controller 13 turns off the defrosting two-way valve 7 and turns on the bypass four-way valve 9 at the time of liquid back.
The electronic control valve 11 is controlled from fully closed to fully open according to the liquid back state of the compressor 1. As a result, a part of the high-temperature high-pressure refrigerant from the compressor 1 flows through the bypass four-way valve 9 into the bypass line 8 as shown by the double-dashed chain line arrow in the figure, and the electronic control valve 11 changes the suction temperature to 5 After the amount of the refrigerant is controlled so as to be ˜7 ° C., the refrigerant is mixed with the refrigerant in which the evaporative gas and the liquid of the refrigeration cycle are mixed and enters the compressor 1, where the liquid back is prevented.

When the outdoor heat exchanger 3 is frosted to perform the defrosting operation, the defrosting two-way valve 7 is turned on, the bypass four-way valve 9 is turned off, and the electronic control valve 11 is fully closed. As a result, a part of the high-temperature and high-pressure refrigerant from the compressor 1 flows into the outdoor heat exchanger 3 as shown by a dashed line in the figure to perform defrosting. This defrosting operation is ended by detection of a defrosting return temperature sensor (not shown) provided in the outdoor heat exchanger 3. That is, the detection value of the defrosting temperature sensor is input to the control device 13, and the control device 13 detects the temperature of the outdoor heat exchanger 3 during the defrosting operation, and when frost is removed and the temperature rises to a predetermined temperature. , The defrosting two-way valve 7 is turned off to end the defrosting operation.

As described above, the controllability is exhibited in the transient state such as the discharge temperature overshoot at the time of starting the compressor, and the cycle can be stabilized early. Further, since the amount of refrigerant flowing through the bypass circuit 10 is extremely small, it does not affect heat exchange in the refrigeration cycle so much. In this way, the reliability of the compressor is improved by eliminating the liquid bag and hunting. Furthermore, by using the electronic control valve 11, it is easy to introduce control such as fuzzy control.

[0027]

In summary, according to the present invention, bypass defrosting can be performed during defrosting without making the refrigeration cycle complex and large, and the refrigerant between the expansion valve and the indoor heat exchanger can be used when the compressor overheats. Is returned to the compressor via the bypass circuit to prevent its overheating, and at the time of liquid back, the high temperature and high pressure refrigerant is returned to the compressor via the bypass circuit to prevent liquid back.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Expansion valve 5 Indoor heat exchanger 10 Bypass circuit 12 Suction temperature sensor

Claims (2)

[Claims] 1. In a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger are sequentially connected, a suction temperature sensor is provided on the suction side of the compressor, and the temperature sensor is used to operate the compressor. Detects overheating and liquid back, when the compressor is overheated, returns the refrigerant between the expansion valve and the indoor heat exchanger to the suction side of the compressor, and when the liquid is back up in the compressor, the refrigerant discharged from the compressor is compressed. An air conditioner having a bypass circuit for returning to the suction side of the air conditioner. 2. In a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger are sequentially connected, a suction temperature sensor is provided on the suction side of the compressor, and the suction side is connected to the discharge side of the compressor. The heating inlet side of the outdoor heat exchanger is connected with a defrost line, the expansion valve and the indoor heat exchanger are connected with a suction side of the compressor with a bypass line, and the defrost line and the bypass line are bypassed. Connected by a four-way valve for use to form a bypass circuit that returns the refrigerant between the expansion valve and the indoor heat exchanger to the suction side of the compressor, and returns the refrigerant discharged from the compressor to the suction side of the compressor. An electronic control valve is connected to a bypass circuit on the downstream side of the bypass four-way valve, the detection value of the suction temperature sensor is input, and the bypass four-way valve is switched based on the detection value and the opening degree of the electronic control valve is controlled. Provide a control device An air conditioner characterized by that.