JPH0340310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a defrosting operation control method during heating operation in an air heat source type air conditioner.

Conventional configurations and their problems Generally speaking, when heating a so-called heat pump type air conditioner, if the temperature of the air used as a heat source decreases, frost will grow on the surface of the heat exchanger on the heat absorption side, and the specified heating capacity will be reduced. Since this is no longer possible, a defrost operation is carried out to remove the frost that has grown.

Figure 1 shows the configuration of a conventional air conditioner, where 1 is a compressor, 2 is a four-way switching valve, 3 is an indoor heat exchanger, 4 is a pressure reducing device, 5 is an outdoor heat exchanger, and 6
is a liquid reservoir (accumulator), which are connected in sequence to form a refrigeration cycle. _F3 is a blower that blows air to the indoor heat exchanger 3, and _F5 is a blower that blows air to the outdoor heat exchanger 5.

In this refrigeration cycle, during heating operation, the refrigerant gas compressed by the compressor 1 flows through the four-way switching valve 2 to the indoor heat exchanger 3, radiates heat, performs heating air conditioning, and becomes a refrigerant liquid, and then the pressure reducing device The refrigerant gas absorbs heat and evaporates in the outdoor heat exchanger 5 whose pressure is reduced by 4, and becomes refrigerant gas again through the four-way switching valve 2, passes through the liquid reservoir 6, and returns to the compressor 6. The refrigerant gas is then compressed again and the above cycle is repeated.

Further, during operation of the above-mentioned refrigeration cycle, when the outside air temperature decreases and frost adheres to the endothermic heat exchanger, that is, the outdoor heat exchanger 5, and this grows, a defrosting operation is performed. In defrosting operation, the four-way switching valve 2 is switched, the blowers F ₃ and F 5 of the indoor heat exchanger 3 and the outdoor heat exchanger ₅ are stopped, and the refrigerant gas compressed by the compressor 1 is transferred to the outdoor heat exchanger. The heat of the refrigerant gas is radiated by the outdoor heat exchanger 5 to melt the frost.

Figure 2 shows the amount G of liquid refrigerant present in the refrigeration cycle.
FIG. 2 is a diagram showing the refrigerant circuit corresponding to each component of the refrigerant circuit shown in FIG. 1, and the numbers 1 to 6 on the horizontal axis indicate the numbers assigned to each component shown in FIG. FIG. 2A shows the state during the heating operation, and FIG. 2B shows the state immediately after the defrosting operation starts when the heating operation is switched to the defrosting operation.

As is clear from FIG. 2, when switching from heating operation to defrosting operation, the four-way switching valve 2 switches to connect the indoor heat exchanger 3 where refrigerant liquid is stored and the liquid reservoir 6. As a result, the refrigerant flows into the liquid reservoir 6 as a liquid. At this time, a large amount of refrigerant liquid flows in, so it is necessary to provide a fairly large liquid reservoir. Further, due to the structure of the liquid reservoir 6, it is impossible to completely store the liquid, and the more refrigerant liquid that flows in, the more the amount that enters the compressor 1 in a liquid state increases. Then, the compressor 1 causes liquid compression, giving a large impact to components such as the cylinder, vane, and piston that constitute the compressor 1.

Further, as shown in FIG. 3, refrigerating machine oil 20 is stored in the lower part of the compressor 1, and the crankshaft of the compressor 1
Refrigerating machine oil 20 is pumped up by an oil pump 13 provided at 0, and is supplied to each sliding part such as the upper bearing 8, cylinder 6, piston 7, and lower bearing 9 through oil supply holes 14, 15, 16, etc. However, when the liquid refrigerant is discharged by the liquid compression, the liquid refrigerant accumulates on the upper surface of the refrigerating machine oil 20 and evaporates there, so the refrigerating machine oil 20 also foams at the same time and flows out of the compressor 1, causing the oil in the refrigerating machine oil 20 to bubble. The oil level of the refrigerating machine oil 20 is lowered than the oil pump 13 by lowering the surface.
As a result, oil is not supplied to each part, and the compressor becomes more worn.

When liquid refrigerant flows into the compressor in this way, there is a problem in that it causes great damage to the compressor and significantly shortens its life.

In FIG. 3, 11 and 12 are a rotor and a stator, respectively, which constitute the electric motor section of the compressor 1, and 6 is a liquid reservoir.

Purpose of the invention The present invention solves the problems of the above conventional example,
The purpose is to extend the life of the compressor.

Structure of the Invention In order to achieve this object, the present invention performs a defrost start preparation operation before starting a defrost operation during heating, and performs a defrost start preparation operation that is continued for a predetermined period of time. An operation period is provided, and during this preparatory operation period for the start of defrosting, the indoor blower is operated and the operation of the compressor is stopped or the capacity of the compressor is reduced.

By providing this defrosting start preparation operation, liquid refrigerant does not flow into the compressor.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 4A and 4B, and FIGS. 5 and 6. Here, the refrigeration cycle structure and compressor structure are conventionally well-known structures, and are the same as those shown in FIGS. 1 and 3.

5 and 6 respectively show operation time charts of the compressor 1, four-way switching valve 2, and blowers F ₃ and F ₅ according to the defrosting operation control method of the present invention.
FIG. 5 shows a case where the compressor 1 has a single capacity, and FIG. 6 shows a case where the compressor 1 has a single capacity.

That is, when using a single-capacity compressor 1 whose capacity is not variable, in _the operation time chart shown in _FIG . However, at this time T ₂
At time T ₁ prior to , the blower F ₃ is operated continuously and the blower F ₅ is stopped. moreover,
The compressor 1 is temporarily stopped from time T ₁ to time T ₂ ,
The period from time T ₁ to time T ₂ is defined as a preparatory operation period for starting defrosting. When the compressor 1 is temporarily stopped at time T ₁ , the pressure on the indoor heat exchanger 3 side decreases, and the refrigerant liquid in the indoor heat exchanger 3 is transferred to the outdoor heat exchanger 5 through the pressure reducing device 4 . This reduces the amount of refrigerant liquid that accumulates in the indoor heat exchanger 3. Reducing the refrigerant liquid accumulated in the indoor heat exchanger 3 can be achieved in a short time because the indoor heat exchanger 3 is cooled by operating the indoor blower _F3 . The amount G of liquid refrigerant in each component of the refrigerant circuit during the preparatory operation period for the start of defrosting is as shown by the solid line in Figure 4A, and compared to the state during heating operation shown by the broken line in the same figure, the indoor heat exchange is Vessel 3
The amount G of liquid refrigerant in is significantly reduced. Thereafter, at time T ₂ , when the four-way switching valve 2 is switched and the compressor 1 is operated again at the same time, defrosting operation is started, but the amount G of liquid refrigerant in each component of the refrigerant circuit immediately after the defrosting operation is as shown in As shown by the solid line in Figure B, compared to the conventional case shown by the broken line in the same figure, that is, the case where there is no preparatory operation period for the start of defrosting,
Less liquid refrigerant returns from the indoor heat exchanger 3 to the liquid reservoir 6, and the refrigerant is prevented from entering the compressor 1 in a liquid state.

Next, the operation time chart when using the variable capacity compressor 1 is as shown in FIG. 6, and the period from time T ₁ to time T ₃ corresponds to the preparatory operation period for starting defrosting.
Between time T ₁ and time T ₂ , indoor fan F ₃
The capacity of the compressor 1 is gradually reduced with the outdoor blower F5 in the operating state and the outdoor fan _F5 in the stopped state. Then, the time T ₂ is reached while the state of the blowers F ₃ and F ₅ is continued.
The compressor 1 is operated at a constant low capacity from time _T3 to time T3, and at time _T3 , the four-way switching valve 2 is switched from the heating operation state to the defrosting operation state, and the indoor blower _F3 is stopped. The capacity of the compressor 1 is increased and defrosting operation is started.

Effects of the Invention As is clear from the above embodiments, the defrosting operation control method for an air conditioner according to the present invention provides a preparatory operation period for starting defrosting before starting the defrosting operation, and during this preparatory operation period for starting defrosting, Reduce or temporarily stop the compressor capacity, and after this period of preparatory operation to start defrosting,
Immediately after switching to defrosting operation, as the liquid refrigerant accumulated in the indoor heat exchanger decreases during this preparatory operation period for starting defrosting, immediately after switching to defrosting operation,
A large amount of liquid refrigerant does not flow into the liquid reservoir or further into the compressor, so the liquid reservoir can be made smaller.
Furthermore, damage to the compressor due to liquid compression can be prevented, and since the high pressure in the refrigerant circuit at the start of defrosting is reduced, the switching noise of the four-way switching valve for defrosting operation is also reduced. In addition, since the indoor fan is operated during the preparatory operation period to start defrosting, the preparatory operation period for defrosting start can be shortened, and the defrosting operation can be started relatively quickly. Since the heat possessed by the exchanger can be used to heat the room until defrosting operation is performed, fluctuations in room temperature can be suppressed.

[Brief explanation of drawings]

Figure 1 is a refrigerant circuit diagram of an air conditioner, Figure 2 A,
B is a liquid refrigerant amount distribution diagram in each component of the refrigerant circuit in the conventional air conditioner defrosting operation control method;
Figure 3 is a cross-sectional view of the compressor section in the refrigerant circuit;
Figures A and B are liquid refrigerant amount distribution diagrams in each component of the refrigerant circuit in the defrosting operation control method of an air conditioner according to the present invention, and Figures 5 and 6 are respectively the defrosting operation control method according to the embodiment of the present invention. This is a time chart. 1... Compressor, 2... Four-way switching valve, 3... Indoor heat exchanger, 4... Pressure reducing device, 5... Outdoor heat exchanger, 6... Liquid reservoir, F ₃ , F ₅ ... Blower.

Claims (1)

[Claims] 1. Before the start of defrosting operation, which is performed by switching the four-way switching valve to reverse cycle during heating operation of an air heat source type air conditioner, a defrosting start preparation period that continues for a predetermined period of time is established, and this defrosting start operation period is established. In defrosting operation control that performs defrosting operation after the preparatory operation period,
A defrosting operation control method for an air conditioner, wherein during the defrosting start preparation operation period, an indoor blower is operated, and a compressor is either stopped or its capacity is reduced.