JPH0422233Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to freezing prevention of an outdoor heat exchanger of an air conditioner.

BACKGROUND OF THE INVENTION Conventionally, in air conditioners, frost forms on the outdoor heat exchanger as the outside temperature falls during heating operation, and various methods have been devised to defrost the heat exchanger.

An example of the conventional air conditioner mentioned above will be described below with reference to the drawings.

FIG. 4 is a refrigeration cycle diagram of a heat pump type air conditioner, which includes a compressor 207, a four-way valve 208, an indoor heat exchanger 209, a pressure reducer 210, and an outdoor heat exchanger 211. During heating, the refrigerant discharged from the compressor 207 flows through the four-way valve 208 as shown by the solid line.
The heat is radiated through the indoor heat exchanger 209 and the pressure is reduced to the pressure reducer 21.
It is depressurized at 0, absorbs heat in the outdoor heat exchanger 211, and returns to the compressor 207 via the four-way valve 208.

When the outside temperature is low during heating, the outdoor heat exchanger 21
The condensed water condensed in step 1 gradually passes through the outdoor heat exchanger 21.
1, the four-way valve 208 is switched to a cooling operation to melt the frost that has formed on the outdoor heat exchanger 211. (Dotted line arrow) FIG. 5 shows an improved version of the refrigeration cycle shown in FIG. Four-way valve 308 and compressor 307
A solenoid valve 313 is provided in the middle of the bypass pipe 305 and connects with the suction pipe between the bypass pipes 305 and 305 to form a parallel circuit. During heating, when the outdoor heat exchanger 311 becomes frosted, the four-way valve 308 is switched to the cooling operation as in the case of FIG. 4, and the solenoid valve 313 is opened so that almost no refrigerant flows to the indoor heat exchanger 309. First, the refrigerant is returned to the suction side of the compressor 307 to perform defrosting operation. (For example, Publication of Utility Model Publication No. 55-45236) Problems that the invention aims to solve However, in the configuration shown in Fig. 4 above, since cooling operation is performed every time defrosting operation is performed, cold air is blown indoors, resulting in poor feeling. It had some problems. In addition, in the configuration shown in Figure 5 above, since the refrigerant is bypassed during defrosting, heat absorption on the indoor side is suppressed and the feeling is improved, and the refrigerant is directly returned to the suction side of the compressor, resulting in input to the compressor. This also increases the defrost time. However, on the other hand, it requires a solenoid valve to open and close the bypass pipe, as well as a temperature sensor or pressure sensor to detect whether frost has formed on the outdoor heat exchanger, and the number of parts such as electronic circuits increases, increasing costs. do. Furthermore, since the solenoid valve is always energized while it is open, the input power increases accordingly.

In view of the above-mentioned problems, the present invention aims to prevent freezing of an outdoor heat exchanger during heating operation of an air conditioner.

Means for Solving the Problems In order to solve the above problems, the air conditioner of the present invention is a heat pump that connects a compressor, a four-way valve, an indoor heat exchanger, a pressure reduction device, and an outdoor heat exchanger in a ring. A bypass pipe is provided from the refrigerant pipe between the outdoor heat exchanger and the pressure reducer, and the other end of the bypass pipe is connected to the suction pipe between the four-way valve and the compressor to form a parallel circuit. In addition, an on-off valve made of a shape-memory alloy whose shape changes is provided in the middle of the bypass pipe.

Function The present invention has the above-mentioned configuration, so that when condensed water forms frost on the outdoor heat exchanger, the four-way valve switches to perform cooling operation and defrost, and at the same time, the on-off valve of the bypass circuit opens and cools the refrigerant. Flows directly to the suction side of the compressor, which suppresses heat absorption on the indoor side and improves the feeling.Also, compressor input increases, reducing defrosting time, and eliminates the need for solenoid valves, sensors, etc. can also be reduced.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 of the accompanying drawings.

Figure 3 shows the refrigeration cycle of a heat pump air conditioner. 7 is a compressor, 8 is a four-way valve, 9 is an indoor heat exchanger, 10 is a pressure reducer, 11 is an outdoor heat exchanger, 5 is a bypass pipe, and 12 is an on-off valve made of a shape memory alloy. A bypass pipe 5 is provided from the refrigerant pipe between the outdoor heat exchanger 11 and the pressure reducer 10, and the other end of the bypass pipe 5 is connected to the suction pipe 6 between the four-way valve 8 and the compressor 7 to form a parallel circuit. , and an on-off valve 12 made of a shape memory alloy whose shape changes is provided in the middle of the bypass pipe 5.

FIG. 1 is a sectional view showing a state in which the on-off valve 12 is closed. 6 is a suction pipe, 5 is a bypass pipe, and the on-off valve 12 is made up of a valve 2, a shape memory alloy spring 1, and a cylinder 4.
A gauge cap 3 is connected to the suction port 14 of the compressor 7. During cooling operation and during heating operation when the outdoor heat exchanger 11 is not frosted, the shape memory alloy spring 1 is stretched, so the valve 2 is pushed by the spring force and closes the flow path of the bypass pipe 5. .

FIG. 2 is a sectional view showing a state in which the on-off valve 12 is open. During heating operation, when the outside air temperature decreases, the evaporation pressure decreases and the outdoor heat exchanger 6
The condensed water gradually forms frost. As frosting progresses, the four-way valve 8 is switched to enter cooling operation, and high-temperature, high-pressure refrigerant flows into the indoor heat exchanger 6, resulting in defrosting operation. At this time, the pressure on the suction side of the compressor 7 becomes close to negative pressure, and the amount of refrigerant circulated through the compressor 7 is extremely reduced. Since the gauge cap 3 is connected to the cylinder 4 from the suction port 14 of the compressor 7, when the suction pressure decreases, the temperature inside the cylinder 4 also decreases. the result,
The shape-memory alloy spring 1 gradually contracts, and the valve 2 that closes the flow path of the bypass pipe 5 opens, allowing the refrigerant to flow directly from the bypass pipe 5 to the suction side of the compressor 7, as shown by the dashed line, so that most of the heat is inside the room. No refrigerant flows into the exchanger 9. When defrosting is completed, the suction pressure of the compressor 7 gradually increases and the valve 2 closes again as shown in FIG.

It is generally known that shape memory alloys undergo deformation at the transformation temperature, that is, they undergo a shape change and return to the memorized shape on both the low temperature and high temperature sides, and the present invention takes advantage of this effect. We are using.

In a typical air conditioner, the intake temperature of the compressor 7 is at least around 0°C during cooling operation, at least around -10°C during heating operation, and about - during defrosting operation. The temperature is around 30℃. Therefore, by setting the transformation temperature of the shape memory alloy to around -30°C, the on-off valve 2 can be opened only during defrosting and closed during normal cooling operation.

Therefore, the outdoor heat exchanger 11 and the pressure reducer 10
A bypass pipe 5 is provided from the refrigerant pipe between the bypass pipe 5 and the other end of the bypass pipe is connected to the suction pipe 6 between the four-way valve 8 and the compressor 7 to form a parallel circuit.
By providing an on-off valve 12 made of a shape memory alloy whose shape changes in the middle, when the outdoor heat exchanger 11 becomes frosted during heating operation, the four-way valve 8 is switched to switch to defrosting operation. Since the on-off valve 12 opens and the refrigerant flows directly to the suction side of the compressor 7 through the bypass pipe 5, almost no refrigerant flows to the indoor heat exchanger 9, and as a result, heat absorption on the indoor side is suppressed and the feeling is improved. . Furthermore, since the refrigerant directly returns to the suction side of the compressor 7, the input to the compressor 7 also increases and the defrosting time can be shortened.
Furthermore, a solenoid valve 13 for opening and closing the bypass pipe 5
Further, there is no need for a pressure sensor or a temperature sensor or an electronic circuit for detecting the opening/closing timing of the electromagnetic valve 13, so the number of parts can be reduced, costs can be reduced, and the structure is simple.
Furthermore, since the solenoid valve 13 is not used, input can also be reduced.

Effects of the invention As is clear from the above explanation, the present invention constructs a heat pump refrigeration cycle by connecting a compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger in a ring. A bypass pipe is provided from the refrigerant pipe between the outdoor heat exchanger and the pressure reducer, and the other end of the bypass pipe is connected to the suction pipe between the four-way valve and the compressor to form a parallel circuit. is equipped with an on-off valve made of a shape-memory alloy that changes its shape, so when the outdoor heat exchanger becomes frosted during heating operation, the four-way valve 8 is switched to defrost operation and the on-off valve is turned off. Since the refrigerant flows directly to the suction side of the compressor through the open bypass pipe, almost no refrigerant flows to the indoor heat exchanger, and as a result, heat absorption on the indoor side is suppressed and the feeling is improved. Furthermore, since the refrigerant directly returns to the suction side of the compressor, the input to the compressor 7 increases as a result, making it possible to shorten the defrosting time. Furthermore, there is no need for solenoid valves to open and close the bypass pipe, as well as pressure sensors or temperature sensors and electronic circuits to detect the timing of opening and closing of the solenoid valves, reducing the number of parts, lowering costs, and simplifying the structure. It is. In addition, since no electromagnetic valve is used, input power can be reduced, and other advantages are provided.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing the structure of an on-off valve in an embodiment of the present invention, Figure 3 is a refrigeration cycle diagram in an embodiment of the present invention, and Figures 4 and 5 are conventional refrigeration systems. It is a cycle diagram. 1... Spring made of shape memory alloy, 2...
Valve, 4...Cylinder, 12...Opening/closing valve.

Claims (1)

[Scope of utility model registration request] Compressor, four-way valve, indoor heat exchanger, pressure reducing device,
A heat pump refrigeration cycle is constructed by sequentially connecting the outdoor heat exchangers in a ring shape, a bypass pipe is provided from the refrigerant pipe between the outdoor heat exchanger and the pressure reducer, and the other end of the bypass pipe is connected to a four-way valve. Connecting the suction pipe between the compressors to form a parallel circuit, and providing an on-off valve having a shape memory alloy in the cylinder part in the middle of the bypass pipe, and connecting the suction side of the compressor and the cylinder part of the on-off valve with a gauge cap. The shape memory alloy is connected to An air conditioner that changes shape to be in an open state, and in which refrigerant flows directly to the suction side of the compressor through the bypass pipe depending on the open state of the on-off valve, thereby performing hot gas bypass defrosting.