JP5851953B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner that performs defrosting operation in heating operation using hot gas using a bypass circuit.

In a conventional air conditioner, when heating operation is performed at a low outside air temperature, frost adheres to the outdoor heat exchanger, and the capacity of the outdoor heat exchanger decreases. In order to prevent this, it is necessary to defrost if more than a certain amount of frost adheres. As a defrosting method, a reverse cycle defrosting method by switching a four-way valve, a hot gas bypass defrosting method in which a hot gas bypass passage from a compressor outlet to an outdoor heat exchanger inlet is provided, and the like are known. However, any of these methods causes a sudden pressure change immediately after switching from the heating operation to the defrosting operation, and gives unpleasant feeling to the resident due to the refrigerant sound and vibration accompanying the sudden refrigerant movement.
As a method for preventing these, there has been a method of stopping or decelerating the compressor before the start of defrosting. However, although the generation of refrigerant noise can be reduced, the defrosting time becomes longer and further improvement has to be made. (For example, see Patent Document 1)

JP 59-191850 A

  This conventional air conditioner has an object to minimize the generation of the switching sound and refrigerant sound of the two-way valve due to the pressure difference before and after the two-way valve provided in the bypass circuit, and to shorten the defrosting time. It is.

The present invention pays attention to this point and solves the above-mentioned drawbacks. In particular, the compressor is configured by sequentially connecting a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger. A bypass circuit that communicates with an outlet side of the machine and a pipe that connects the expansion valve and the outdoor heat exchanger. The bypass circuit is provided with a two-way valve that opens and closes the bypass circuit. An air conditioner that includes a defrost control unit that detects defrosting of a exchanger and determines the start and end of a defrosting operation, opens a two-way valve of the bypass circuit, and performs defrosting. A discharge temperature sensor for detecting the discharge temperature of the outdoor heat exchanger and an outdoor heat exchanger sensor for detecting the temperature of the outdoor heat exchanger, and the defrost control unit is stepwise until the expansion valve is almost fully opened at the start of defrosting. after the opening has been increased to the discharge temperature sensor and the outdoor heat exchange sensor When the temperature difference X reaches the predetermined temperature difference X1, the rotation Y of the compressor is reduced to the predetermined rotation speed Y1, the two-way valve is opened, and then the expansion valve is closed to the predetermined opening during defrosting and compression. The rotation of the compressor is increased to a predetermined rotational speed Y2, and defrosting is performed. At the end of the defrosting operation, the expansion valve is opened, the rotation of the compressor is decreased to the predetermined rotational speed Y1, and then the two-way valve is closed. The opening degree of the expansion valve and the rotation speed of the compressor are returned to the heating operation to return to the normal heating operation.

  According to this invention, the generation of the switching sound of the two-way valve and the refrigerant sound at the start of the defrosting can be made extremely small, and the heating operation is continued even during the defrosting. Therefore, it is possible to provide an air conditioner that prevents the air from being applied.

The refrigeration circuit diagram of one Example of this invention. Explanatory drawing of the defrost operation.

Next, an air conditioner according to the present invention will be described with reference to an embodiment shown in the drawings.
1 is a compressor whose rotational speed changes stepwise from 30 Hz to 110 Hz, 2 is a four-way valve for switching the flow direction of refrigerant during cooling operation and heating operation, 3 is an indoor heat exchanger, and 4 is a pressure reducing device The expansion valve 5 is an outdoor heat exchanger, 6 is an outdoor heat exchange sensor according to a frost detector attached to the inlet side of the outdoor heat exchanger 5 during heating operation, 7 is an accumulator, 8 is a compressor 1 , A bypass circuit that connects any point on the pipe connecting the expansion valve 4 and the outdoor heat exchanger 5, 9 is a two-way valve that opens and closes the bypass circuit 8, and 10 is the compressor 1. It is the discharge temperature sensor provided in the outlet side piping.

  11 is blown to the indoor heat exchanger 3 to send warm air into the room in the heating operation, and indoor air blower fan to send out cold air in the cooling operation. 12 is blown to the outdoor heat exchanger 5 and outdoor heat in the heating operation. An outdoor blower fan that absorbs heat into the exchanger 5 and exhausts heat during cooling operation.

  Reference numeral 13 denotes an indoor unit that is installed on an indoor wall or the like, and adjusts the room temperature by blowing out hot air or cold air. Reference numeral 14 is an outdoor unit that is installed outside and connected to the indoor unit 12 and the communication pipe 15 through a communication wire (not shown). Outdoor unit.

  Reference numeral 16 denotes an indoor control unit that controls the air conditioner according to a user's temperature setting and other settings by a remote controller (not shown), and 17 denotes a compressor 1 according to a command from the indoor control unit 15. An outdoor control unit 18 that controls the rotation frequency, the opening degree of the expansion valve 4 and the like is a defrost control unit provided in the outdoor control unit 17 and detects frost generated in the outdoor heat exchanger 5 during heating operation. The defrosting operation is performed.

  The operation of the defrosting operation will be described. When the four-way valve 2 is switched to the heating operation (in the direction of the broken arrow in FIG. 1) and the heating operation is performed, the high-temperature refrigerant discharged from the compressor 1 is converted into the indoor heat exchanger. 3, warm air is blown into the room by the indoor fan 11 and heating is performed. The refrigerant whose temperature has been reduced after the heat radiation in the indoor heat exchanger 3 is reduced in pressure by the expansion valve 4 and reaches a low temperature and reaches the outdoor heat exchanger 5. It returns to the compressor 1 through the valve 2.

  Since the outdoor heat exchanger 5 is below freezing when the outside air temperature is low, if the heating operation is continued, frost gradually adheres to the outdoor heat exchanger 5 and the heat exchange capacity decreases due to clogging of the outdoor heat exchanger 5. Furthermore, frost increases. In order to prevent this, the defrosting operation is performed due to a decrease in the value of the outdoor heat exchange sensor 6.

  The defrosting operation is performed by opening the two-way valve 9 provided in the bypass circuit 8 and sending the warm discharged refrigerant to the outdoor heat exchanger 5, and at the start of the defrosting operation, before and after the two-way valve 9 Since the pressure difference is large, noise with a large opening sound of the two-way valve 9 and refrigerant sound is generated. Therefore, in order to reduce this noise, after the defrosting condition is established, the expansion valve 4 is gradually opened gradually to be in the fully open state, and the discharge temperature sensor 10 (about 80 ° C.) and the outdoor heat exchange sensor 6 (about After the temperature difference X of −10 ° C. becomes small and reaches the predetermined temperature difference X1 (about 20 deg), if the rotational speed Y of the compressor 1 is further reduced to the predetermined rotational speed Y1 (about 60 Hz), the two-way valve The pressure difference around 9 further decreases, and even when the two-way valve 9 is switched, the opening sound and refrigerant sound of the two-way valve 9 are almost eliminated.

  After the switching of the two-way valve 9, the indoor heating is continued simultaneously with the defrosting operation. Therefore, the expansion valve 4 is throttled to the defrosting opening degree, and the rotation of the compressor is set to the rotational speed Y2 (about approx. 110 Hz), the frost adhering to the outdoor heat exchanger 5 is melted, and when the defrosting termination condition is satisfied from the time when the frost is almost eliminated, the temperature of the refrigeration circuit, etc., the normal speed of the expansion valve 4 Is opened, the rotational speed of the compressor 1 is reduced to a predetermined rotational speed Y2 (about 60 Hz), and the two-way valve 9 is closed, the defrosting operation is completed, the opening degree of the expansion valve 4 and the rotation of the compressor 1 The number returns to normal heating operation. A series of operations related to the defrosting operation is controlled by the defrosting operation control unit 18, and the defrosting operation control unit 18 is provided in the outdoor control unit 17.

  Thus, the generation of the switching sound of the two-way valve 9 and the refrigerant sound at the start of the defrosting can be made extremely small, and the heating operation is continued even during the defrosting, so that the user feels uncomfortable due to the defrosting operation. The air conditioner which prevents giving can be provided.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Indoor heat exchanger 4 Expansion valve 5 Outdoor heat exchanger 6 Outdoor heat exchange sensor 8 Bypass circuit 9 Two-way valve 10 Discharge temperature sensor 16 Indoor control part 17 Outdoor control part 18 Defrost control part

Claims (1)

A pipe that connects a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger sequentially, and connects the outlet side of the compressor, the expansion valve, and the outdoor heat exchanger. The bypass circuit is provided with a two-way valve that opens and closes the bypass circuit, and detects the frost formation of the outdoor heat exchanger during the heating operation and determines the start and end of the defrost operation. In an air conditioner that is provided with a frost control unit and performs defrosting by opening the two-way valve of the bypass circuit, a discharge temperature sensor that detects the discharge temperature of the compressor, and a temperature of the outdoor heat exchanger An outdoor heat exchange sensor is provided, and the defrost control unit increases the opening stepwise until the expansion valve is almost fully opened at the start of defrosting , and then the temperature of the discharge temperature sensor and the outdoor heat exchange sensor. When the difference X reaches the predetermined temperature difference X1, the rotation Y of the compressor is rotated by a predetermined amount. Decrease to Y1, open the two-way valve, then close the expansion valve to a predetermined opening at the time of defrosting, increase the rotation of the compressor to a predetermined rotational speed Y2 to perform defrosting, and at the end of the defrosting operation After opening the expansion valve and reducing the rotation of the compressor to the predetermined rotational speed Y1, the two-way valve is closed, and then the opening degree of the expansion valve and the rotational speed of the compressor are returned to the heating operation so that the normal heating operation is performed. An air conditioner characterized by being restored.

Images