JP4989735B2 - Refrigeration air conditioner - Google Patents

Description

  The present invention relates to a refrigeration air conditioner, and more particularly, to oil supply to a compressor.

  Some vapor compression type refrigerating and air-conditioning apparatuses are provided with an accumulator in a suction pipe between the evaporator and the compressor for storing liquid refrigerant that could not be vaporized in the evaporator. This accumulator accumulates liquid refrigerant, thereby preventing the compressor from being damaged by a so-called liquid back generated when the liquid refrigerant flows into the compressor as it is.

  This accumulator is installed on the suction side of a compressor in a refrigerating and air-conditioning apparatus in which a compressor, a condenser, an expansion mechanism, and an evaporator are connected in an annular shape via a refrigerant pipe. Store.

  When the liquid refrigerant is accumulated in the main body container of the accumulator (for example, when the air conditioner is in a heating operation where the outside air temperature is low), the liquid refrigerant and the oil may be separated into two layers. This phenomenon occurs not only when the oil incompatible with the refrigerant is used but also when the oil compatible with the refrigerant is used. For example, even when a compatible polyol ester oil is used for R410A, two-layer separation occurs at a temperature of −37 ° C. or lower. In this case, since the specific gravity of the liquid refrigerant is larger than the specific gravity of the oil, if the liquid refrigerant layer exists in the lower layer and the oil return hole is installed at the bottom of the accumulator, it becomes impossible to supply oil to the compressor.

  In order to solve such a problem, for example, “… connecting the oil level detecting means for detecting the oil level of the refrigerating machine oil stored in the storage chamber, and the oil level detecting means and the outlet pipe located near the bottom of the storage chamber are connected. Connecting means and an auxiliary oil return hole provided in the connecting means located near the oil level detecting means. The oil level detecting means uses a float whose density is lower than that of the refrigerating machine oil, and the connecting means is flexible. A tube is used "(for example, refer to Patent Document 1). In this accumulator, when the liquid refrigerant accumulates in the storage chamber and the refrigerating machine oil is separated into two layers, the oil level detection means (floating body) floats on the upper surface of the refrigerating machine oil even if the liquid refrigerant layer exists in the lower layer, Refrigerating machine oil is sucked into the oil return pipe from the auxiliary oil return hole and supplied to the compressor.

Japanese Patent Laid-Open No. 11-14200 (see paragraph 0022, FIG. 1)

However, during the operation of the refrigerating and air-conditioning apparatus, since the refrigerant flows into the accumulator vigorously, the surface of the stored oil violently waves and the floating body on the refrigerating machine oil is not stable. In such a state, there exists a subject that the oil supply to a compressor cannot be performed stably.
In addition, the flexible tube connected to the floating body has problems such as durability and clogging of auxiliary oil return holes, and further requires oil level detection means (floating body). There were problems such as increased costs.

  The present invention has been made in order to solve the above-described problems. A highly reliable refrigerating and air-conditioning apparatus that can stably supply oil to a compressor even when liquid refrigerant is accumulated in an accumulator is provided. The purpose is to obtain.

  The refrigerating and air-conditioning apparatus according to the present invention includes a refrigerant circuit in which a compressor, a condenser, a decompression unit, an evaporator, and an accumulator are annularly connected via a refrigerant pipe, and refrigerating machine oil and refrigerant exhibiting compatibility are introduced. In the refrigerating and air-conditioning apparatus, the control device for controlling the capacity of the compressor, and the control device are configured so that the evaporating temperature of the refrigerant exceeds a critical temperature at which the refrigerating machine oil and the refrigerant are separated. Control the capacity.

  According to the refrigerating and air-conditioning apparatus according to the present invention, even when the liquid refrigerant is accumulated in the accumulator, the refrigerant evaporating temperature is higher than the critical temperature at which the refrigerating machine oil and the refrigerant are separated. The refrigerant is not separated into two layers, and stable oil supply to the compressor is possible, and a highly reliable refrigeration air conditioner can be obtained.

It is a refrigerant circuit of the refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention. It is sectional drawing of the accumulator of the refrigeration air conditioner of FIG. It is sectional drawing of the other example of the accumulator of the refrigeration air conditioner of FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a refrigeration air conditioner according to the invention will be described with reference to the accompanying drawings.

Embodiment 1 FIG.
1 is a refrigerant circuit diagram of a refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the refrigerating and air-conditioning apparatus according to Embodiment 1 includes an outdoor unit 1 and an indoor unit 2. The outdoor unit 1 includes a compressor 3 that compresses and discharges the refrigerant, a condenser 4 that condenses the refrigerant discharged from the compressor 3, and an accumulator 7 that stores liquid refrigerant and refrigeration oil. The indoor unit 2 includes an expansion valve 5 as decompression means for decompressing the refrigerant flowing out from the condenser 4, an evaporator 6 that evaporates the refrigerant decompressed by the expansion valve 5, and a blower fan 6 a that sends air to the evaporator 6. And. The compressor 3, the condenser 4, the expansion valve 5, the evaporator 6, and the accumulator 7 are connected in a ring shape by a refrigerant pipe 11 to constitute a refrigeration cycle (refrigerant circuit).

  The refrigerating and air-conditioning apparatus according to Embodiment 1 includes a control device 8 that controls the capacity of the compressor 3, the opening degree of the expansion valve 5, and the rotational speed of the blower fan 6a. Consists of My Computer etc. A temperature sensor 9 and a pressure sensor 10 are attached to the refrigerant pipe 11 on the inlet side of the accumulator 7, and the suction superheat degree is obtained from the measurement outputs of the temperature sensor 9 and the pressure sensor 10. Is detected.

Next, the flow of the refrigerant in the refrigeration air conditioner in Embodiment 1 will be described.
The high-temperature and high-pressure gas refrigerant discharged from the compressor 3 is condensed and liquefied by the condenser 4, then reduced in pressure by the expansion valve 5 to become a two-phase refrigerant, evaporated and gasified by the evaporator 6, and then compressed through the accumulator 7. The refrigerant is circulated by forming a refrigeration cycle that is sucked into the machine 3 and circulated.

Next, the flow of refrigerating machine oil in the refrigerating and air-conditioning apparatus according to Embodiment 1 will be described.
The refrigerating machine oil discharged together with the gas refrigerant from the compressor 3 flows into the accumulator 7 through the condenser 4, the expansion valve 5 and the evaporator 6. In the accumulator 7, the refrigerating machine oil and the gas refrigerant are separated, and the separated oil stays at the bottom of the accumulator 7.

2 and 3 are configuration examples of the accumulator 7.
In the example shown in FIG. 2, an oil return hole 13 is provided at the bottom of the outlet tube 12 inserted into the accumulator 7.
In the example shown in FIG. 3, an oil return hole 13 is provided at the bottom of the accumulator 7.
In the accumulator 7 of FIGS. 2 and 3, all the refrigerating machine oil staying there is returned to the compressor 3 through the oil return hole 13.

  By the way, in the operation in which the liquid refrigerant is accumulated in the accumulator 7, for example, in the case of the liquid back operation due to the failure that the expansion valve 5 is not closed, in the air conditioner, when the excess refrigerant is generated in the heating operation with the low outside air temperature, or in the refrigerator For example, there is an operation mode in which the blower fan 6a of the evaporator 6 is stopped for a predetermined time in order to precool the evaporator after completion of the frost operation.

As described above, when the liquid refrigerant is accumulated in the accumulator 7, if the refrigerant is incompatible with the refrigerating machine oil, the liquid refrigerant and the refrigerating machine oil are separated into two layers, but the refrigerant is compatible with the refrigerating machine oil. Even if, for example, R410A is used as the refrigerant and polyol ester oil is used as the refrigerating machine oil, the two layers are separated at a low temperature of -37 ° C. In this case, the density of the R410A refrigerant is about 1200 kg / m ³ , the density of the polyol ester oil is about 1000 kg / m ³ , and the refrigerant has a higher specific gravity than the refrigerating machine oil. It will be formed on the liquid refrigerant.

  When the liquid refrigerant and the refrigerating machine oil are separated into two layers and the refrigerating machine oil layer is formed on the liquid refrigerant, it becomes impossible to supply oil to the compressor 3 from the oil return hole 13 installed in the bottom of the accumulator 7. In addition, poor lubrication due to oil depletion of the compressor 3 occurs, causing damage.

  In the refrigerating and air-conditioning apparatus according to the first embodiment, refrigerating machine oil and refrigerant exhibiting compatibility are introduced, and when the control device 8 detects a liquid back based on the measurement outputs of the temperature sensor 9 and the pressure sensor 10, The capacity of the compressor 3 is controlled, and the evaporation temperature, that is, the temperature measured by the temperature sensor 9 or the saturation temperature of the pressure measured by the pressure sensor 10 exceeds the critical temperature at which the refrigerating machine oil and the refrigerant are separated. To control. For this reason, the refrigerating machine oil and the refrigerant stored in the accumulator 7 are not separated, and the oil can be supplied from the oil return hole 13 to the compressor 3. By the way, at this time, the refrigerant is also supplied to the compressor 3 through the oil return hole 13, but the amount is small and liquid back does not occur.

In addition, although the liquid return detection means of this invention which detects the liquid return in the suction pipe of the compressor 3 (detects a liquid back | bag) was demonstrated, the example comprised by the control apparatus 8, the temperature sensor 9, and the pressure sensor 10 was demonstrated. The present invention is not limited to this. For example, a liquid level sensor or a float that detects the liquid level in the accumulator 7 may be used.
In addition, the evaporation temperature is controlled by controlling at least one of the opening degree of the expansion valve 5 and the air volume (rotation speed) of the blower fan 6a together with the control of the capacity of the compressor 3 or instead of the capacity of the compressor 3. The evaporating temperature of the refrigerant may be a temperature exceeding the critical temperature at which the refrigerating machine oil and the refrigerant are separated.

  As described above, in the first embodiment, even when the liquid refrigerant is accumulated in the accumulator 7, the liquid refrigerant and the refrigerating machine oil are operated above the critical temperature at which the two-layer separation is performed. The refrigerating machine oil is not separated into two layers, and the refrigerating machine oil can always be stably supplied to the compressor 3 to obtain a highly reliable refrigerating air conditioner.

  DESCRIPTION OF SYMBOLS 1 Outdoor unit, 2 Indoor unit, 3 Compressor, 4 Condenser, 5 Expansion valve, 6 Evaporator, 6a Blower fan, 7 Accumulator, 8 Control apparatus, 9 Temperature sensor, 10 Pressure sensor, 11 Refrigerant piping, 12 Derived pipe , 13 Oil return hole.

Claims (5)

In a refrigeration air conditioner in which a compressor, a condenser, a decompression means, an evaporator, and an accumulator are provided with a refrigerant circuit connected in an annular shape through a refrigerant pipe, and refrigeration oil and refrigerant exhibiting compatibility are introduced,
A control device for controlling the capacity of the compressor;
The control device controls the capacity of the compressor so that the evaporation temperature of the refrigerant exceeds a critical temperature at which the refrigerating machine oil and the refrigerant are separated from each other. Liquid return detection means for detecting liquid return in the suction pipe of the compressor,
The said control apparatus controls the capacity | capacitance of the said compressor so that the evaporation temperature of the said refrigerant | coolant will become the temperature exceeding the said critical temperature, if the said liquid return detection means detects a liquid return. Item 2. The refrigeration air conditioner according to item 1. A blower fan for blowing air to the evaporator;
The pressure reducing means is composed of an expansion valve,
The controller is
With the control of the capacity of the compressor or instead of the capacity of the compressor,
The at least one of the opening degree of the expansion valve and the air volume of the blower fan is controlled so that the evaporation temperature of the refrigerant becomes a temperature exceeding the critical temperature. Refrigeration air conditioner of description.   The refrigerating and air-conditioning apparatus according to any one of claims 1 to 3, wherein a refrigerant having a specific gravity greater than that of the refrigerating machine oil is used.   The refrigerating and air-conditioning apparatus according to any one of claims 1 to 4, wherein the accumulator includes an oil return hole for supplying the refrigerating machine oil to the compressor at a lower part thereof.

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