JP3653348B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner including a plurality of compressors and refrigerant heating means, and more particularly to a technique for eliminating refrigerant stagnation in a stop-side compressor and its suction pipe during refrigerant heating operation.
[0002]
[Prior art]
In recent years, heat pump type air conditioners that perform heating using air as a heat source are increasing in place of conventional cooling only machines. However, in the heat pump type air conditioner, when the outside air temperature is extremely low, the difference between the evaporation temperature of the refrigerant in the outdoor heat exchanger and the outside air temperature becomes very small, and heating is hardly performed. Therefore, in addition to a normal outdoor heat exchanger (air heat exchanger), a refrigerant heater is provided in the outdoor unit, and heat exchange between hot water or the like and the refrigerant (that is, refrigerant heating) is performed. Some have supplied relatively high-temperature refrigerant to the compressor. In this type of air conditioner, the latent heat of condensation in the indoor heat exchanger can be ensured regardless of the outside air temperature, so that sufficient heating is possible even in severe winter.
[0003]
On the other hand, a large air conditioner is known in which a plurality of compressors are installed in an outdoor unit, and the capacity and the number of operating units of the compressors are changed in accordance with an increase or decrease in the air conditioning load. For example, some compressors having two compressors combine a constant speed compressor and a variable compressor having a maximum capacity equal to that of the constant speed compressor, and perform capacity control over a wide range. In this air conditioner, when a capacity of 50% or less is required, only the variable compressor is driven, and when a capacity of 50% or more is required, both compressors are driven together. Accordingly, if the variable compressor can switch the capacity in five stages, the capacity can be switched in ten stages as a whole.
[0004]
[Problems to be solved by the invention]
In a heat pump type air conditioner equipped with a plurality of compressors and refrigerant heaters, if some compressors are stopped for capacity control when operating while performing refrigerant heating, Liquid refrigerant sometimes accumulated in the compressor and the suction pipe to the compressor (refrigerant stagnation). This is because the saturation temperature of the refrigerant rises when heated, and the refrigerant condenses in contact with the compressor and the suction pipe that are exposed to the outside air without any flow of the refrigerant and becomes low temperature. Progress gradually while continuing driving.
[0005]
When the refrigerant stagnates in the compressor or the suction pipe, a large amount of liquid refrigerant flows into the compression mechanism at the time of restart, and the compressor may break down due to liquid compression. In addition, if a large amount of refrigerant stagnates in the stopped compressor or its suction pipe, there is a shortage of refrigerant circulating in the operating compressor or refrigerant circuit, and air conditioning may not be performed smoothly. Furthermore, when the amount of refrigerant stagnation in the compressor increases, the winding of the electric motor may break down due to being immersed in the liquid refrigerant. A crankcase heater is attached to the lower part of the compressor. This prevents the refrigerant from being dissolved in the lubricating oil enclosed when the compressor is stopped. There was no ability to vaporize the refrigerant, and there was little effect on the liquid refrigerant that had fallen into the suction pipe.
[0006]
This invention is made | formed in view of the said situation, and it aims at providing the air conditioner which eliminated the stagnation of the refrigerant | coolant in the compressor of the stop side in the refrigerant | coolant heating operation, and its suction piping.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the invention of claim 1, a plurality of compressors connected in parallel for independent adjustment of heating capacity and operated alone or simultaneously, and refrigerant heating means utilized as a heat source during heating operation, Among the plurality of compressors, the compressor that can be stopped during the refrigerant heating operation includes a compressor heating means including a main crankcase heater and a sub crankcase heater, and the compressor heating means. Control means for operating the compressor, and when the operation of only the compressor that can be stopped during the refrigerant heating operation is stopped, the main crankcase heater and the sub crankcase heater are energized by this control means, and both compressors are operated. It is proposed that only the main crankcase heater is energized when the engine is stopped.
[0008]
According to the present invention, for example, an electric heater having sufficient heating capacity is attached to one of the two compressors that may be stopped during the refrigerant heating operation, and the stop side compressor during the refrigerant heating operation is provided. Energize the electric heater. As a result, the refrigerant no longer condenses inside the stop-side compressor, and a compressor failure or the like due to the stagnation of the refrigerant is prevented.
[0011]
According to a second aspect of the present invention, there is provided an air conditioner comprising: refrigerant heating means for performing refrigerant heating operation by heating refrigerant sucked into the compressor; and a plurality of compressors connected in parallel to the same refrigerant circuit. In this machine, a compressor having a plurality of suction pipes respectively corresponding to the plurality of compressors and a communication passage for communicating the plurality of suction pipes is proposed.
[0012]
According to the present invention, even if a part of the compressors are stopped during operation, the suction pipe communicates with the suction pipe of the operation side compressor via the communication path. The refrigerant is sucked into the operation side compressor, and the refrigerant is prevented from stagnation.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 shows a refrigerant circuit (shown by a solid line) and an electric circuit (shown by an alternate long and short dash line) of an air conditioner including an indoor unit 1 and an outdoor unit 3. Housed in the indoor unit 1 are an indoor heat exchanger 5, an electric fan 7, an electric expansion valve 9, and the like, and an indoor ECU 11 that drives and controls the electric fan 7, the electric expansion valve 9, and the like. Further, in the outdoor unit 3, a pair of compressors 21, 23 arranged in parallel, an electromagnetic four-way valve 25, an outdoor heat exchanger 27 and a refrigerant heater 29 arranged in parallel, an accumulator 31, an electric fan 33 and the outdoor ECU 35 that controls the drive of the compressors 21 and 23, the four-way valve 25, the electric fan 33, and the like are housed. The outdoor heat exchanger 27 is a normal air heat exchanger, but the refrigerant heater 29 is a water heat exchanger that exchanges heat between hot water at a predetermined temperature (50 ° C. in this embodiment) and the refrigerant. It is a vessel.
[0015]
The devices in the indoor unit 1 and the outdoor unit 3 are connected by refrigerant pipes 51 to 64, and the refrigerant circulates in the direction indicated by the solid arrow during heating (during refrigerant heating operation), and the broken line during cooling operation. The refrigerant circulates in the direction indicated by the arrow. Further, the refrigerant pipe 63 and the refrigerant pipe 64 are communicated with each other through a communication pipe 65, and the refrigerant can move between the refrigerant pipes 63 and 64. In the figure, 37 and 39 are electromagnetic shut-off valves that are opened and closed by the outdoor ECU 35, and shut off the refrigerant pipes 58 and 56 to the outdoor heat exchanger 27 or the refrigerant heater 29 during cooling or heating. Reference numerals 41, 43, and 45 are check valves that allow the refrigerant to flow only in one direction, and are interposed in the refrigerant pipes 51, 52, and 60.
[0016]
FIG. 2 shows a layout around the compressors 21 and 23 and the accumulator 31. A left compressor (hereinafter referred to as a first compressor) 21 in FIG. 2 is a variable type and is preferentially driven during an air conditioning operation. The right compressor (hereinafter referred to as a second compressor) 23 is a constant speed type and is driven only when a capacity of 50% or more is required. A main crankcase heater 71 is attached to the lower part of the compressors 21 and 23, and two sub crankcase heaters 73 and 75, which are compressor heating means, are attached to the upper part of the second compressor 23. Has been. The main crankcase heater 71 and the sub crankcase heaters 73 and 75 have the same capacity (in this embodiment, 32 W), and are energized and controlled by the outdoor ECU 35 as shown in FIG.
[0017]
On the other hand, the refrigerant pipe 62 connected to the upper part of the accumulator 31 branches into two refrigerant pipes (hereinafter referred to as suction pipes) 63 and 64 and then descends along the upper surface of a base plate (not shown). After being piped, it rises and is connected to both compressors 21 and 23. The suction pipes 63 and 64 are communicated via the communication pipe 65 at the rising portions to the compressors 21 and 23.
[0018]
Hereinafter, the operation of the present embodiment will be described.
[0019]
When the outside air temperature drops below a predetermined value and heating using air as a heat source becomes impossible, the outdoor ECU 35 switches from the normal heating operation to the refrigerant heating operation. That is, the shutoff valve 37 is closed while the shutoff valve 39 is opened, and the refrigerant supply destination is changed from the outdoor heat exchanger 27 to the refrigerant heater 29. Then, the electric fan 33 is stopped and hot water from a hot water source (not shown) is supplied to the refrigerant heater 29.
[0020]
Thereby, the liquid refrigerant from the indoor heat exchanger 5 flows into the refrigerant heater 29 via the refrigerant pipes 55 and 56, and is relatively hot (for example, 20 to 40 ° C.) due to heat exchange with warm water therein. Gas refrigerant. The gas refrigerant flows into the accumulator 31 through the refrigerant pipes 57 and 61 and is sucked into the first and second compressors 21 and 23 through the refrigerant pipes 62 to 64. At this time, since the check valve 45 is provided in the refrigerant pipe 60, the inflow of gas refrigerant to the outdoor heat exchanger 27 side is prevented. The gas refrigerant sucked into the first and second compressors 21 and 23 is compressed therein to become high temperature and pressure and flows into the indoor heat exchanger 5 through the refrigerant pipes 51 to 54. The high-temperature gas refrigerant releases heat energy to the room air blown to the electric fan 7 to perform heating, while gradually condensing in the indoor heat exchanger 5 to become liquid refrigerant again.
[0021]
Now, when the capacity | capacitance request | requirement to an outdoor unit becomes small, outdoor ECU35 performs the capacity | capacitance control of the 1st compressor 21, and stops the 2nd compressor 23. FIG. Then, the gas refrigerant from the accumulator 31 is sucked only into the first compressor 21 through the refrigerant pipes 62 and 63 and compressed inside thereof, and then the indoor heat exchanger through the refrigerant pipes 51 and 53 to 54. 5 will flow into. At this time, since the check valve 43 is provided in the refrigerant pipe 52, the gas refrigerant discharged from the first compressor 21 is prevented from flowing into the second compressor 23 side.
[0022]
Next, a procedure for preventing the stagnation of the refrigerant in the second compressor 23 and the suction pipe 64 will be described.
[0023]
When the second compressor 23 is stopped during the refrigerant heating operation, the refrigerant may stagnate inside the suction pipe 64 or the second compressor 23. That is, when the suction pipe 64 or the second compressor 23 that has been exposed to the outside air and has a low temperature due to no refrigerant flow is touched, the gas refrigerant that has been heated and has a high saturation temperature easily condenses as a liquid refrigerant. May accumulate inside these. In the present embodiment, in order to prevent such a stagnation of the refrigerant, the following two means are employed.
[0024]
When the operation of the air conditioner is started, the outdoor ECU 35 repeatedly executes the crankcase heater energization control subroutine shown in FIG. 4 at a predetermined control interval. When this subroutine is started, the outdoor ECU 35 first reads operation information from various subroutines processed in parallel in step S1, and then determines whether or not the second compressor 23 is stopped in step S3. .
[0025]
If this determination is No, that is, if the second compressor 23 is operating, the outdoor ECU 35 stops energization of the main crankcase heater 71 and the sub crankcase heaters 73 and 75 in step S5. This is because the refrigerant circuit temperature is sufficiently high during operation, so that condensation of the refrigerant in the second compressor 23 and the suction pipe 64 cannot occur, and conversely, unnecessary heating is performed. This is because the temperature of the second compressor 23 rises excessively.
[0026]
When the determination in step S3 is Yes, the outdoor ECU 35 determines whether or not the first compressor 21 is operating and the refrigerant heating operation is performed in step S7. If this determination is No, the outdoor ECU 35 starts energizing only the main crankcase heater 71 in step S9. That is, during the cooling operation or the normal heating operation, the temperature of the second compressor 23 is kept high to some extent in order to prevent the refrigerant from being mixed in the enclosed lubricating oil. Further, even during the refrigerant heating operation, if the first compressor 21 is also stopped, there is no possibility that the refrigerant will stagnate, so the temperature of the second compressor 23 is kept high to some extent for the reasons described above.
[0027]
If the determination in step S7 is Yes, that is, if only the first compressor 21 is operating during the refrigerant heating operation, the outdoor ECU 35 energizes the main crankcase heater 71 and the sub crankcase heaters 73 and 75 in step S11. To start. Thereby, the 2nd compressor 23 is heated entirely, The internal temperature becomes higher than the saturation temperature of a gas refrigerant | coolant, and condensation of the liquid refrigerant | coolant which causes a refrigerant | coolant to sleep is prevented.
[0028]
On the other hand, the gas refrigerant from the accumulator 31 flows into the suction pipe 64 through the refrigerant pipe 62 and then gradually condenses by touching the tube wall that has become low temperature. And since the liquid refrigerant produced | generated by condensation has larger specific gravity than a gas refrigerant, it accumulates in the lower part of the suction piping 64. FIG. In this embodiment, however, the suction pipe 64 is communicated with the suction pipe 63 via the communication pipe 65, and the communication part is provided at the lowermost part of the suction pipe 64 and at the rising portion to the second compressor 23. Therefore, a gas refrigerant flows in the suction pipe 64, and almost no liquid refrigerant is generated. Further, even when the liquid refrigerant is generated, it is quickly sucked into the first compressor 21 without accumulating in the suction pipe 64. As a result, the stagnation of the liquid refrigerant in the suction pipe 64 is completely prevented, and the liquid refrigerant is prevented from flowing into the second compressor 23 even when the second compressor 23 is restarted.
[0029]
As described above, in the present embodiment, the sub-crankcase heaters 73 and 75 are attached to the second compressor 23 to appropriately control energization, and the suction pipes 63 and 64 of both the compressors 21 and 23 are communicated. Therefore, it was possible to prevent the stagnation of the refrigerant in the second compressor 23 and the suction pipe 64 thereof. As a result, problems such as compressor failure due to liquid compression, air conditioning failure due to lack of refrigerant, and insulation breakdown of the windings of the electric motor, which have been problems with conventional devices, have been completely solved.
[0030]
The description of the specific embodiment is finished above, but the present invention is not limited to the above-described embodiment. For example, in the above embodiment, the compressor heating means and the communication path are used together, but a predetermined effect can be obtained with only one of them. In the above embodiment, the present invention is applied to an air conditioner having one variable compressor and one constant speed compressor. However, one variable compressor and two or more compressors are used. You may apply to the air conditioner provided with the constant speed type compressor. In addition, the present invention may be applied to an air conditioner that includes a plurality of constant speed compressors and operates them alternately, and in that case, it is desirable to include a sub crankcase heater in all the compressors. . Moreover, although the said embodiment is applied to the air conditioner provided with the electric compressor, it may be applied to a gas heat pump type air conditioner or the like, and is provided with a plurality of indoor units and outdoor units. You may apply. Furthermore, the specific configuration of the apparatus, the control procedure, and the like can be changed as appropriate without departing from the spirit of the present invention.
[0031]
【The invention's effect】
As described above, according to the refrigerator of the present invention, the compressor stopped during the refrigerant heating operation is heated by the compressor heating means, or the suction pipes of the plurality of compressors are communicated. It is possible to prevent the stagnation of the refrigerant in the suction pipe and the troubles such as the compressor failure due to the liquid compression, the air conditioning failure due to the lack of the refrigerant, and the insulation breakdown of the winding of the electric motor.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a layout around a compressor and an accumulator.
FIG. 3 is a side view of the compressor.
FIG. 4 is a flowchart showing a procedure of a crankcase heater energization control subroutine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Indoor unit 3 Outdoor unit 21 1st compressor 23 2nd compressor 27 Outdoor heat exchanger 29 Refrigerant heater 31 Accumulator 35 Outdoor ECU
37, 39 Shut-off valve 63, 64 Suction pipe 65 Communication pipe 71 Main crankcase heater 73, 75 Sub crankcase heater

Claims (2)

In an air conditioner having a plurality of compressors connected in parallel for adjustment of heating capacity and operated alone or simultaneously and a refrigerant heating means used as a heat source during heating operation, among the plurality of compressors, The compressor that can be stopped during the refrigerant heating operation includes compressor heating means including a main crankcase heater and a sub crankcase heater, and control means for operating the compressor heating means, and is stopped during the refrigerant heating operation. When the operation of only the compressor is stopped, the main crankcase heater and sub-crankcase heater are energized by this control means when only the compressor is stopped. When both compressors are stopped, only the main crankcase heater is energized. Because of this, due to a decrease in heating capacity, the compressor that has been shut down when the compressor is operating alone is heated to An air conditioner characterized by being difficult to the medium stagnation. 2. The air conditioner according to claim 1 , further comprising a plurality of suction pipes respectively corresponding to the plurality of compressors and a communication passage communicating the plurality of suction pipes.

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