JPH0914767A - Refrigerating machine - Google Patents

Abstract

PURPOSE: To achieve a two-layer separation avoidance operation alarming against insufficiency of lubrication by a method wherein the temperature of oil is compared with a saturation temperature of a refrigerant and the refrigerant and lubricating oil are determined to separate in two layers within a compressor when a difference of the oil temperature is below zero from the saturation temperature. CONSTITUTION: A comparing section 35 compares a signal indicating the temperature of oil from an oil temperature correction calculating section 33 connected to a discharge pipe temperature sensor 31 with a signal indicating a saturation temperature from a saturation temperature calculating section 34 to which the signal is outputted from an input value selecting part 32 after the signal indicating a suction pressure both during the cooling and heating operations is selected by the input value selecting part connected to a suction pressure sensor 27. As a result of the comparison, when a difference between the oil temperature and the saturation temperature is below zero, the refrigerant and lubricating oil are determined by a two-layer separation judging section 37 to separate in two layers in a compressor 25. Thus, an alarming is generated against the insufficiency of lubrication of the compressor 25 and a two- layer separation avoidance operation is performed thereby enabling preventing of wearing and burning of a sliding part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator that uses oil having a specific gravity smaller than that of a refrigerant and incompatibility with the refrigerant as a lubricating oil of a compressor. The present invention relates to a refrigerator that can detect that lubricating oil and two layers have separated.

[0002]

2. Description of the Related Art Conventionally, when an oil that is incompatible with a refrigerant is used in a refrigerator, as shown by a black dot in FIG. When dissolved, a two-layer separation occurs where the oil and refrigerant split into two layers. And
At this time, if (specific gravity of refrigerant)> (specific gravity of oil), the lower layer becomes a refrigerant rich layer having an extremely low oil concentration.

As an operation mode in which the two-layer separation occurs,
There are modes in which liquid back occurs transiently, such as startup (sleep activation), start / stop, and defrost. When the two-layer separation occurs in the oil sump of the compressor of the refrigerator, the two-layer separation surface D crosses the oil supply port S depending on the conditions, as shown in FIG. 7 (B). Then, the oil in the lower liquid refrigerant rich layer R is sucked in through the oil supply port S and is supplied to the sliding portion of the compressor C without oil being sucked in through the oil supply port S. Then, there is a problem that the lubrication failure of the compressor C occurs, causing friction and seizure of the sliding portion.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a refrigerator capable of detecting that the refrigerant and the lubricating oil are separated into two layers in the compressor.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 uses an oil having a specific gravity smaller than that of a refrigerant and substantially incompatible with the refrigerant, in a compressor 5,
In the refrigerator used as the lubricating oil of No. 25, oil temperature detecting means 15, for detecting the temperature of the oil in the compressors 5, 25,
16, 31, 33, refrigerant saturation temperature detecting means 7, 8, 10, 11, 27, 30, 32, 34 for detecting the saturation temperature of the refrigerant determined by the pressure in the compressors 5, 25, and the oil. The oil temperature detected by the temperature detecting means 15, 16, 31, 33,
The refrigerant saturation temperature detecting means 7, 8, 10, 11, 27, 30,
When the saturation temperature of the refrigerant detected by 32 and 34 is compared and the difference α between the oil temperature and the saturation temperature α = (the oil temperature−the saturation temperature) becomes zero or less (α ≦ 0). In addition, two-layer separation determination means 12, 18, 35, for determining that the refrigerant and the lubricating oil are separated into two layers in the compressors 5, 25.
And 37 are provided.

According to a second aspect of the present invention, in the refrigerator according to the first aspect, the two-layer separation determination means 12, 18, 3 are provided.
5, 37, when the operating frequency of the compressors 5 and 25 is a predetermined value and the difference α is less than or equal to zero (α ≦ 0), the refrigerant and the lubricating oil are the compressors. When it is judged that the compressor 5 and 25 are separated into two layers and the operating frequency of the compressors 5 and 25 becomes higher than the predetermined value, the difference α is increased by the increased amount. When the value αa becomes less than or equal to zero (α ≦ 0), it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressors 5,25, and the compressors 5,25 When the operating frequency becomes less than the predetermined value, when the value αa obtained by reducing the difference α by the smaller amount becomes zero or less (α ≦ 0), the refrigerant and the lubrication are It is characterized in that it is judged that oil and oil are separated into two layers in the compressors 5 and 25.

Further, the invention of claim 3 is a refrigerator using a non-compatible oil having a specific gravity smaller than that of the refrigerant and substantially incompatible with the refrigerant as a lubricating oil of the compressor, An outside air temperature sensor 57 that detects the outside air temperature, a start / stop circuit 58 that counts the number of times of starting and stopping the compressor 55 from an on state to an off state, a signal Sout indicating the outside air temperature from the outside air temperature sensor 57, and the above A signal Sn representing the number of times of starting and stopping from the starting and stopping circuit 58 is input, and when the number of times of starting and stopping of the compressor 55 reaches a predetermined number of times of determination determined by the outside air temperature, the refrigerant in the compressor The lubricating oil is separated into two layers, and a two-layer separation determination means 60 for determining that this separation surface is just before passing the oil supply port in the compressor is provided.

[0008]

As shown in FIG. 8, under a predetermined pressure in the compressor, the oil temperature (more accurately, the temperature of the mixed liquid of the oil and the refrigerant) is the saturation temperature of the refrigerant in the melting region of the refrigerant and the oil. Higher than. On the other hand, in the two-layer separation region of the refrigerant and the oil, the oil temperature becomes almost equal to the saturation temperature of the refrigerant. The invention of claim 1 is an application of the property shown in FIG.

That is, in the refrigerator according to the first aspect of the invention, the two-layer separation determining means 12, 18, 35, 37 detects the oil temperature detected by the oil temperature detecting means 15, 16, 31, 33, and the refrigerant saturation. The saturation temperature of the refrigerant detected by the temperature detecting means 7, 8, 10, 11, 27, 30, 32, 34 is compared. The determination means 12, 18, 35, 37 determines that the difference α between the oil temperature and the saturation temperature α = (the oil temperature−the saturation temperature) is less than or equal to zero (α ≦
When it becomes 0), it is judged that the refrigerant and the lubricating oil are separated into two layers in the compressors 5 and 25.

Therefore, the judging means 12, 18, 3
If it is determined that the 5 and 37 are separated into the two layers, the insufficient lubrication of the compressors 5 and 25 is warned, and the two-layer separation avoidance operation is performed. Can be prevented.

Further, in the refrigerator of the second aspect of the present invention, the two-layer separation determination means 12, 18, 35, 37 are arranged so that when the operating frequency of the compressors 5, 25 is a predetermined value, the difference α
Is less than or equal to zero (α ≦ 0), it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressors 5 and 25. Further, the judging means 12, 18, 35, 37 are
When the operating frequency of the compressors 5, 25 becomes larger than the predetermined value and the value αa obtained by increasing the difference α by the larger amount becomes zero or less (α ≦ 0). ,
It is determined that the refrigerant and the lubricating oil are separated into two layers in the compressors 5 and 25. In addition, the determination means 12,
18, 35, 37, when the operating frequency of the compressor 5, 25 becomes smaller than the predetermined value, the value αa obtained by reducing the difference α by the smaller amount is not more than zero (α ≦
When it becomes 0), it is judged that the refrigerant and the lubricating oil are separated into two layers in the compressors 5 and 25.

When the operating frequencies of the compressors 5 and 25 increase, it becomes difficult to separate the two layers even if the difference α has the same value. On the other hand, when the operating frequencies of the compressors 5 and 25 decrease,
Even if the difference α has the same value, the two layers are easily separated. Therefore, when the operating frequencies of the compressors 5 and 25 increase or decrease with respect to a predetermined value, the determining means 1
By increasing or decreasing the value α, which is the reference value of 2, 18, 35, and 37, the two-layer separation determination in the compressors 5 and 25 can be performed more accurately.

By the way, when the compressor is repeatedly turned on and off at start-up and starts, the refrigerant liquid returns to the compressor every time it is turned on, and the refrigerant accumulates in the compressor. Then, when the refrigerant accumulated in the compressor reaches a predetermined amount, two-layer separation occurs in which the refrigerant and the oil are separated into two layers. According to the third aspect of the invention, the two-layer separation is detected by utilizing the correlation between the number of times of starting and stopping and the occurrence of the two-layer separation.

That is, according to the third aspect of the invention, in the two-layer separation determination means 60, the number of times of starting and stopping the compressor 55 from the ON state to the OFF state has reached a predetermined determination number determined by the outside air temperature. At this time, it is judged that the refrigerant and the lubricating oil in the compressor 55 are separated into two layers, and this separation surface is just before passing the oil supply port in the compressor 55.

Therefore, when the judging means 60 judges that the two-layer separation surface is just before passing over the filler port,
By issuing an alarm of insufficient lubrication and performing a two-layer separation avoidance operation, it is possible to prevent wear and seizure of the sliding portion.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

[First Embodiment] FIG. 1 shows the configuration of an air conditioner according to a first embodiment of the present invention. This air conditioner has an indoor heat exchanger 1 which is connected by a refrigerant line.
An outdoor heat exchanger 2, a throttle expansion part 3, a four-way switching valve 4, a compressor 5, and an accumulator 6 are provided. This air conditioner uses oil having a specific gravity smaller than that of the refrigerant used in the air conditioner and having no compatibility with the refrigerant as a lubricating oil.

A first temperature sensor 7 is attached to the indoor heat exchanger 1. A second temperature sensor 8 is attached to the outdoor heat exchanger 2. The first and second temperature sensors 7 and 8 are connected to the input value selection unit 10. The input value selection unit 10 is connected to the pipe pressure loss correction calculation unit 11. Also, this calculation unit 11
Are connected to the comparison unit 12.

On the other hand, a third temperature sensor 15 is connected to the discharge pipe 13 from the compressor 5, and the third temperature sensor 15 is connected to an oil temperature correction calculation section 16. The calculation unit 16 is connected to the comparison unit 12.

The comparison unit 12 is connected to the frequency correction unit 17, and the frequency correction unit 17 is connected to the two-layer separation determination unit 18.

The air conditioner having the above-mentioned structure is provided with the above-mentioned first, second, and
The operation of determining the two-layer separation of the refrigerant and the lubricating oil in the compressor 5 based on the temperatures detected by the third temperature sensors 7, 8, 15 will be described.

First, the input value selection unit 10 receives the signal S1 representing the temperature T1 of the indoor heat exchanger 1 from the first temperature sensor 7, and receives the temperature T of the outdoor heat exchanger 2 from the second temperature sensor 8.
A signal S2 representing 2 is received. Then, as shown in the lower part of FIG. 1, when the compressor 5 is a high-pressure dome type, the input value selection unit 10 selects and outputs the signal S2 representing the temperature T2 of the outdoor heat exchanger 2 during cooling. On the other hand, during heating, the signal S1 representing the temperature T1 of the indoor heat exchanger 1 is selected and output.
Further, when the compressor 5 is a low-pressure dome type, the selection unit 10 selects and outputs the signal S1 indicating the temperature T1 of the indoor heat exchanger 1 during cooling, while the outdoor heat exchanger 2 during heating.
The signal S2 representing the temperature T2 of is selected and output.

When the compressor 5 is of the high-pressure dome type, and during cooling, the pipe pressure loss correction calculation unit 11 sets the temperature (condensation temperature) T2 of the outdoor heat exchanger 2 to the discharge pipe 13 To the outdoor heat exchanger 2 (condenser) is added to the pressure loss conversion temperature ΔTpc
Calculate (T2 + ΔTpc). Then, this added value (T2
+ ΔTpc) is converted into the dome internal pressure Pc of the compressor 5, and the saturated temperature Ts of the refrigerant in the dome is calculated from the converted dome internal pressure Pc.

When the compressor 5 is a high-pressure dome type, and during heating, the pipe pressure loss correction calculation unit 11 sets the temperature (condensation temperature) T1 of the indoor heat exchanger 1 to the indoor heat from the discharge pipe 13. The pressure loss conversion temperature ΔTph obtained by converting the pressure loss up to the exchanger 1 (condenser) into temperature is added, and the added value (T1 + ΔTph)
Is calculated. Then, the added value (T2 + ΔTph) is converted into the dome internal pressure Ph of the compressor 5, and the saturated temperature Ts of the refrigerant in the dome is calculated from the converted dome internal pressure Ph.

Further, when the compressor 5 is a low pressure dome type, and during cooling, the pipe pressure loss correction calculation unit 11 converts the pressure loss from the indoor heat exchanger 1 into the suction pipe into a temperature loss. The converted temperature ΔTpc is subtracted from the temperature (evaporation temperature) T1 of the indoor heat exchanger 1 to obtain a subtracted value (T1-ΔTpc)
Is calculated. Then, the subtracted value (T1−ΔTpc) is converted into the dome internal pressure Pc of the compressor 5, and the saturated temperature Ts of the refrigerant in the dome is calculated from the converted dome internal pressure Pc.

Further, when the compressor 5 is of the low-pressure dome type and at the time of heating, the pipe pressure loss correction calculation unit 11 converts the pressure loss from the outdoor heat exchanger 1 to the suction pipe into a pressure loss. The converted temperature ΔTph is subtracted from the temperature (evaporation temperature) T2 of the outdoor heat exchanger 2 to obtain a subtracted value (T2-ΔTph)
Is calculated. Then, the subtracted value (T2-ΔTph) is converted into the dome internal pressure Ph of the compressor 5, and the saturated temperature Ts of the refrigerant in the dome is calculated from the converted dome internal pressure Ph.

On the other hand, the oil temperature correction calculation unit 16 receives the signal S3 output from the discharge pipe temperature sensor 15, corrects the discharge pipe temperature T3 represented by the signal S3, and determines the oil in the compressor 5 Calculate the temperature To.

Next, the comparison unit 12 receives a signal indicating the saturation temperature Ts from the pipe pressure loss correction calculation unit 11 and a signal indicating the oil temperature To from the oil temperature correction calculation unit 16. Then, the comparison unit 12 compares the saturation temperature Ts with the oil temperature To and subtracts the saturation temperature Ts from the oil temperature To to obtain a difference α = (oil temperature To) − (saturation temperature Ts). calculate.

Next, the frequency correction unit 17 is operated by the compressor 5
Receiving a signal representing the driving frequency of the signal, and adding the correction value Δ to the difference α in accordance with the driving frequency to obtain the corrected difference αa.
= (Α + Δ) is calculated. The relationship between the correction value Δ and the driving frequency is directly proportional, and is 0 ° C. when the driving frequency is 60 Hz, as shown in FIG. 4 (B). The reason for performing such frequency correction is that if the drive frequency is lower than the predetermined frequency (60 Hz), the stirring effect cannot be obtained up to the bottom of the compressor 5 and the amount of heat generation is small, so (oil temperature To)-(saturation temperature Even if Ts) = α is 0 or more, two layers may be separated at the bottom, and conversely, if the frequency is higher than a predetermined frequency, the stirring effect is large. Because there is a possibility. By this frequency correction, the presence or absence of the two-layer separation can be grasped more accurately. The signal processing process up to this point is simplified and shown in FIG.

Next, the two-layer separation determination section 18 receives the signal indicating the correction difference αa from the frequency correction section 17, and when the correction difference αa becomes less than or equal to zero (αa ≦ 0), the refrigerant is determined. It is determined that the lubricating oil and the lubricating oil are separated into two layers in the compressor 5, and a signal indicating that the two layers are separated is output. On the other hand, the two-layer separation determination unit 18 determines the correction value αa.
Is greater than zero (αa> 0), it is determined that the refrigerant and the lubricating oil are not separated into two layers in the compressor 5, and a signal indicating that they are not separated into two layers is output.

If the two-layer separation determination section 18 outputs a signal indicating that two layers are separated, a warning of insufficient lubrication of the compressor 5 is issued to perform the two-layer separation avoidance operation. It is possible to prevent friction and seizure of the sliding portion of the compressor due to the separation of the two layers.

Second Embodiment Next, FIG. 2 shows the configuration of an air conditioner as a second embodiment. In this second embodiment,
An indoor heat exchanger 21, an outdoor heat exchanger 22, a throttle expansion unit 23, a four-way switching valve 24, a compressor 25, and an accumulator 26, which are connected by a refrigerant pipe, respectively. This air conditioner uses, as a lubricating oil, oil having a specific gravity smaller than that of the refrigerant used in the air conditioner and having no compatibility with the refrigerant.

A suction pressure sensor 27 is attached to a suction pipe to the accumulator 26. In addition, the discharge pipe 28
A discharge pressure sensor 30 and a discharge pipe temperature sensor 31 are attached to the. The second embodiment also includes an input value selection unit 32 connected to the suction pressure sensor 27 and the discharge pressure sensor 30, and an oil temperature correction calculation unit 33 connected to the discharge pipe temperature sensor 31. ing.

The input value selection unit 32 is the saturation temperature calculation unit 3
4 and the saturation temperature calculation unit 34 is connected to the comparison unit 35. On the other hand, the oil temperature correction calculator 33
Is connected to the comparison unit 35. The comparison unit 35 is connected to the frequency correction unit 36, and the frequency correction unit 36 is connected to the two-layer separation determination unit 37.

The air conditioner having the above-described structure is provided with the suction pressure sensor 27, the discharge pressure sensor 30, and the discharge pipe temperature sensor 31.
The operation of determining the two-layer separation in the compressor 25 on the basis of the signal from will be described.

First, the input value selection unit 32 outputs the signal Ss representing the suction pressure Ps in the suction pipe from the suction pressure sensor 27.
In response to the discharge pressure P from the discharge pressure sensor 30
A signal Sd representing d is received. Then, as shown in the lower part of FIG. 2, when the compressor 25 is a high-pressure dome type, the input value selection unit 32 selects the signal Sd representing the discharge pressure Pd during both cooling and heating, and The signal Sd is output to the saturation temperature calculation unit 34. On the other hand, when the compressor 25 is a low-pressure dome type, the input value selection unit 32 selects the signal Ss representing the suction pressure Ps during both cooling and heating, and the signal Ss is selected.
s is output to the saturation temperature calculation unit 34.

Next, the saturation temperature calculation unit 34 determines the discharge pressure P
When a signal Sd representing d is received, a saturation temperature conversion formula for the discharge pressure is used to change the discharge pressure Pd from the compressor 25.
The saturation temperature Ts of the refrigerant at is calculated. When receiving the signal Ss representing the suction pressure Ps, the saturation temperature calculation unit 34 calculates the saturation temperature Ts of the refrigerant in the compressor 25 from the suction pressure Ps using the saturation temperature conversion formula for the suction pressure. To do.

On the other hand, the oil temperature correction calculation unit 33 receives the signal St output from the discharge pipe temperature sensor 31, corrects the discharge pipe temperature Td represented by the signal St, and corrects the oil in the compressor 25. Calculate the temperature To.

Next, the comparison section 35 receives the signal representing the saturation temperature Ts from the saturation temperature calculation section 34 and the signal representing the oil temperature To from the oil temperature correction calculation section 33, and receives the saturation temperature T.
s is compared with the oil temperature To, the saturation temperature Ts is subtracted from the oil temperature To, and the difference α = (oil temperature To) − (saturation temperature Ts)
Is calculated.

Next, the frequency correction unit 36 receives the signal representing the drive frequency of the compressor 25, adds the correction value Δ to the difference α according to the drive frequency, and corrects the difference αa =
Calculate (α + Δ). The relationship between the correction value Δ and the driving frequency is directly proportional, and is 0 ° C. when the driving frequency is 60 Hz, as shown in FIG. 4 (B). The signal processing process up to this point is simplified and shown in FIG.

Next, the two-layer judging section 38 is used by the frequency correcting section 3
When the signal representing the correction difference αa is received from 6 and the correction difference αa becomes zero or less (αa ≦ 0), the refrigerant and the lubricating oil are separated into two layers in the compressor 25. Then, a signal indicating that the two layers are separated is output. On the other hand, when the correction value αa exceeds zero (αa> 0), the two-layer separation determination unit 37 indicates that the refrigerant and the lubricating oil are not separated into two layers in the compressor 25. Is output.

When the two-layer separation determination section 37 outputs a signal indicating that two layers are separated, a lubrication shortage alarm is issued to perform the two-layer separation avoidance operation. It is possible to prevent friction and seizure of the sliding part due to.

[Third Embodiment] Next, FIG. 3 shows the configuration of an air conditioner as a third embodiment. This air conditioner
An indoor heat exchanger 51, an outdoor heat exchanger 52, a throttle expansion section 53, a four-way switching valve 54, a compressor 55, and an accumulator 56, which are connected to each other through refrigerant lines, are provided. This air conditioner uses oil having a specific gravity smaller than that of the refrigerant used in the air conditioner and having no compatibility with the refrigerant as a lubricating oil.

The air conditioner also has an outside air temperature sensor 57 for detecting the outside air temperature. The air conditioner also includes a start / stop circuit 58 and a two-layer separation detection circuit 60. The two-layer separation detection circuit 60 includes an outside air temperature sensor 5
7, the signal Sout indicating the outside air temperature Tout, the signal Sss indicating the start / stop time tss from the start / stop circuit 58, and the start / stop count n.
A signal Sn indicating is input.

The start / stop circuit 58 does not count the on / off operation as start / stop when the compressor 55 is stopped after being continuously operated for 5 minutes or more. In addition, the start / stop circuit 58
When the compressor 55 is continuously operated for 10 minutes or more, the count number of the start / stop count is returned to zero and a new count is started. The reason for this is that the refrigerant has been discharged from the compressor 55 in the state of continuous operation for 10 minutes or more.

As shown in FIG. 5, the two-layer separation detection circuit 60 is arranged so that when the number of times n the compressor 55 is started and stopped exceeds the number of times Nj determined by the outside air temperature tout, the refrigerant in the compressor 55 is cooled. And the lubricating oil are separated into two layers, and it is judged that this separated surface exceeds the oil supply port in the compressor 55.

The two-layer separation detection circuit 60 of the air conditioner having the above-mentioned configuration receives the signal Sout from the outside air temperature sensor 57 and detects the outside air temperature Tout. Then, the two-layer separation detection circuit 60 receives the signals Sss and Sn from the start / stop circuit 58, and the number n of start / stop of turning the compressor 55 from the ON state to the OFF state is determined by the outside air temperature tout. When the predetermined number of times of judgment Nj is reached, it is judged that the refrigerant and the lubricating oil in the compressor 55 are separated into two layers, and this separation surface is just before passing over the oil supply port in the compressor 55.

Specifically, when the outside air temperature is −2 ° C.,
As shown in FIG. 6, the start / stop circuit 58 counts the start / stop count n according to the start / stop pattern in which the compressor 55 is turned on / off. Then, as the number of times of starting / stopping n increases to 1, 2, ..., The oil concentration (wt%) at the filler port decreases.
Then, when the number of times of starting and stopping n reaches 3, the two-layer separation detection circuit 60 receives the signal Sn indicating that the number of times of starting and stopping n = 3 from the starting and stopping circuit 58, and the refrigerant in the compressor 55 It is judged that the lubricating oil is separated into two layers, and this separated surface is just before passing the oil supply port in the compressor 55. When this determination is made, if the two-layer separation detection circuit 60 outputs a lubrication shortage alarm signal to perform the two-layer separation avoidance operation, the sliding portion friction and seizure of the compressor due to poor lubrication can be prevented. Can be prevented.

[0049]

As is apparent from the above, in the refrigerator of the first aspect of the invention, the two-layer separation determination means detects the oil temperature detected by the oil temperature detection means and the refrigerant detected by the refrigerant saturation temperature detection means. Compare with saturation temperature. When the difference α between the oil temperature and the saturation temperature α = (oil temperature−saturation temperature) becomes less than or equal to zero (α ≦ 0), the determination means determines that the refrigerant and the lubricating oil are It is determined that the compressor is separated into two layers.

Therefore, according to the present invention, the presence / absence of the two-layer separation in the compressor can be determined. Further, when the determination means determines that the two layers are separated, the insufficient lubrication of the compressor is warned, and the two-layer separation avoidance operation is performed, so that wear and seizure of the sliding portion can be prevented. Can be prevented.

Further, in the refrigerator according to the second aspect of the present invention, the two-layer separation determination means causes the difference α to be zero or less (α ≦ 0) when the operating frequency of the compressor is a predetermined value. Then, it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressor. Further, when the operating frequency of the compressor becomes higher than the predetermined value, the determining means increases the difference α by an amount corresponding to the higher value, and the value becomes zero or less (α ≦ 0). Then, it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressor. Further, when the operating frequency of the compressor becomes lower than the predetermined value, the determining means reduces the difference α by a value corresponding to the decrease, and the value becomes zero or less (α ≦ 0). Then, it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressor.

When the operating frequency of the compressor increases,
Even if the difference α has the same value, it becomes difficult to separate the two layers, while when the operating frequency of the compressor decreases, even if the difference α has the same value, the two layers easily separate. Therefore, when the operating frequency of the compressor is increased or decreased with respect to a predetermined value, the determination means increases or decreases the determination reference value α, so that the two-layer separation in the compressor is performed. The judgment can be made more accurately.

According to a third aspect of the present invention, the two-layer separation determination means is configured so that, when the number of times of starting and stopping the compressor from the on state to the off state reaches a predetermined number of determinations determined by the outside air temperature. It is judged that the refrigerant and the lubricating oil in the compressor are separated into two layers, and this separation surface is just before passing the oil supply port in the compressor.

Therefore, according to the present invention, the presence / absence of the two-layer separation in the compressor can be determined. Further, when the determination means determines that the two-layer separation surface is just before passing over the oil supply port, an alarm of insufficient lubrication is issued, and the two-layer separation avoidance operation is performed. It is possible to prevent burn-in.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an air conditioner as a first embodiment of a refrigerator of the present invention.

FIG. 2 is a block diagram showing a configuration of an air conditioner as a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an air conditioner as a third embodiment of the present invention.

FIG. 4A is a diagram showing a flow of signal processing of the present invention, and FIG. 4B is a frequency correction characteristic diagram.

FIG. 5 is a diagram showing that, in a third embodiment of the present invention, the number of times of starting and stopping increases until the two-layer separation surface passes over the fuel filler port as the outside air temperature rises.

FIG. 6 is a time chart showing how the oil concentration in the oil supply port gradually decreases and two-layer separation occurs as the compressor starts and stops when the outside air temperature is −2 ° C.

FIG. 7 (A) is a two-layer separation diagram showing the two-layer separation region with respect to temperature and refrigerant fraction, and FIG. 7 (B) is a schematic diagram showing the two-layer separation state in the compressor. .

FIG. 8 shows the saturation temperature of the refrigerant in the compressor with a broken line,
It is a solubility diagram which showed the temperature of oil by the solid line.

[Explanation of symbols]

1,21,51 ... Indoor heat exchanger, 2,22,52 ... Outdoor heat exchanger, 3,23,53 ... Throttle expansion part, 4,24,54 ... Four way switching valve, 5,25,55 ... Compression Machine, 6, 26, 56 ... Accumulator, 7 ... First temperature sensor, 8 ... Second temperature sensor, 10, 32 ... Input value selection unit, 11 ... Pipe pressure loss correction calculation unit, 12, 35 ... Comparison unit, 13 ... Discharge pipe, 15 ... Third temperature sensor, 16, 33 ... Oil temperature correction calculation section, 17, 3
6 ... Frequency correction unit, 18, 37 ... Two-layer separation determination unit, 27
... suction pressure sensor, 30 ... discharge pressure sensor, 31 ... discharge pipe temperature sensor, 34 ... saturation temperature calculation unit, 57 ... outside air temperature sensor, 58 ... start / stop circuit, 60 ... two-layer separation detection circuit.

Claims (3)

[Claims] 1. A refrigerator using oil, which has a specific gravity smaller than that of a refrigerant and is substantially incompatible with the refrigerant, as a lubricating oil for the compressor (5, 25). , 25) oil temperature detection means (15, 16, 31, 33) for detecting the temperature of the oil, and a refrigerant saturation temperature for detecting the saturation temperature of the refrigerant determined by the pressure in the compressor (5, 25). Detection means (7,8,1
0, 11, 27, 30, 32, 34), the oil temperature detected by the oil temperature detection means (15, 16, 31, 33), and the refrigerant saturation temperature detection means (7, 8, 10, 11, Two
7, 30, 32, 34) is compared with the saturation temperature of the refrigerant, and the difference α = (oil temperature−saturation temperature) between the oil temperature and the saturation temperature is zero or less (α ≦ 0). ),
Two-layer separation determination means (12, 1) for determining that the refrigerant and the lubricating oil are separated into two layers in the compressor (5, 25).
8, 35, 37) and a refrigerator. 2. The refrigerator according to claim 1, wherein the two-layer separation determination means (12, 18, 35, 37) is used when the operating frequency of the compressor (5, 25) is a predetermined value. When the difference α becomes less than or equal to zero (α ≦ 0), it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressor (5, 25), When the operating frequency of (525) becomes larger than the above-mentioned predetermined value, the difference α becomes
When the increased value (αa) becomes zero or less (α ≦ 0), it is determined that the refrigerant and the lubricating oil are separated into two layers in the compressor (525). However, when the operating frequency of the compressor (5, 25) becomes lower than the predetermined value, the difference α becomes
When the reduced value (αa) becomes less than or equal to zero (α ≦ 0), the refrigerant and the lubricating oil are separated from each other by the compressor (5, 25).
A refrigerator characterized in that it is judged to be separated into two layers inside. 3. An outside air temperature for detecting an outside air temperature in a refrigerator using a non-compatible oil having a specific gravity smaller than that of the refrigerant and having substantially no compatibility with the refrigerant as a lubricating oil of a compressor. A sensor (57), a start / stop circuit (58) for counting the number of start / stop times when the compressor (55) is turned from an on state to an off state, and a signal indicating the outside air temperature from the outside air temperature sensor (57).
(Sout) and a signal (Sn) indicating the number of times of starting and stopping from the starting and stopping circuit (58) are input, and the number of times of starting and stopping the compressor (55) is determined by the outside air temperature. Is reached, the refrigerant and lubricating oil in the compressor are separated into two layers, and the two-layer separation determination means (60) for determining that this separation surface is just before passing over the oil supply port in the compressor. A refrigerator characterized by being provided.