JP2002139261A - Refrigeration cycle apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the wear of slide parts such as bearings of a compressor provided in a refrigeration cycle using an HFC refrigerant, and reduce the sludge produced in mechanochemical reaction due to the wear, thereby improving the reliability. SOLUTION: The refrigeration cycle is composed of a compressor having an oil pan for holding a refrigeration oil in a container, a condenser for condensing a refrigerant discharged from the compressor, an expander for expanding the condensed refrigerant and an evaporator for evaporating the expanded refrigerant. As the refrigerant an HFC type one is used, and as the refrigeration machine oil an oil having a density inverting temperature at which the density of the oil exceeds the liquid density of the refrigerant, lower than a lower limit condensation temperature in operation of the refrigeration cycle is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating cycle such as a refrigerating air conditioner such as an air conditioner, a refrigerator and a refrigerating machine, and uses an HFC-based refrigerant as a refrigerant.

[0002]

2. Description of the Related Art A refrigeration cycle such as an air conditioner, a refrigerator and a freezer is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-1.
No. 03797. FIG. 14 shows an example of a conventional refrigeration cycle. In the figure, 1 is a compressor, 2 is a first heat exchanger, and is a condenser during cooling operation. Reference numeral 3a denotes a throttle mechanism such as an expansion valve, and 4 denotes a second heat exchanger, which is an evaporator 4 for a cooling operation, and is connected in sequence to form a refrigeration cycle.

[0003] In recent years, refrigerants used in refrigeration cycles include HFC refrigerants having little influence on the global environment, for example, HFC32, HFC125, and HFC134a mixed refrigerants, HFC125, HFC143a, and HFC13.
A mixed refrigerant of 4a, a mixed refrigerant of HFC32 and HFC125, a simple refrigerant of HFC134a, and the like are used. As the refrigerating machine oil 10, an ester oil, an ether oil, or a hard alkylbenzene oil that is incompatible with the HFC refrigerant is used.

Next, the behavior of the refrigerant and the refrigerating machine oil 10 will be described. An oil sump 1a is provided at a lower part of the compressor 1,
If a compatible oil is used, the refrigerant oil 10
Is present in the oil reservoir 1a. The oil pump 1b sucks up the refrigerating machine oil 10 or the mixed solution of the refrigerating machine oil 10 and the refrigerant accumulated in the oil reservoir 1a, and the refrigerating machine oil 10 or the mixed liquid of the refrigerating machine oil 10 and the refrigerant is slid on bearings or the like. After lubricating the moving part, the oil is returned to the oil reservoir 1a.

At this time, a part of the refrigerating machine oil 10 is discharged from the compressor discharge pipe 1f to the refrigerating cycle together with the refrigerant compressed in the compression mechanism 1c. The refrigerant and the refrigerating machine oil 10 are circulated through the condenser 2, the expansion mechanism 3a such as an expansion valve, and the evaporator 4, and then sucked into the compressor 1 again from the compressor suction pipe 1g. If there is a container for storing excess refrigerant such as the receiver 6 and the accumulator 5 in the middle of the refrigerant circuit, the refrigerating machine oil 10 is stored in the container such as the receiver 6 and the accumulator 5 and provided in the container. By the operation of the oil return mechanism, the refrigerating machine oil is returned to the refrigeration cycle.

[0006]

For example, in a conventional refrigeration cycle using a combination of an ester oil as a compatible oil and an HFC-based refrigerant, the refrigerant does not contain chlorine. The lubricating performance is reduced and the wear of the sliding part is increased as compared with the combination of (eg, subject to environmental regulations after 2003) and mineral oil.

[0007] This is because chlorine contained in the HCFC22 refrigerant has an action of suppressing wear of the sliding portion under boundary lubrication of the sliding portion such as a bearing, that is, an extreme pressure effect. Therefore, H
If a CFC-based refrigerant is used, the abrasion of the sliding portion tends to be suppressed, but the HCFC refrigerant destroys the ozone layer and adversely affects the global environment. Therefore, when using an HFC refrigerant that does not destroy the ozone layer, the refrigerant does not have an extreme pressure effect and simply dilutes the refrigerating machine oil to lower the oil viscosity and lower the lubrication performance. Under boundary lubrication such as between a vane portion and a rolling piston of a rotary compressor, abrasion has increased to cause a compressor failure.

When the HFC-based refrigerant is used in combination with an incompatible refrigerating machine oil, the liquid refrigerant may be separated into two phases depending on conditions so that the liquid refrigerant layer is positioned below the refrigerating machine oil layer. In a compressor or the like, the oil pump cannot suck the refrigerating machine oil, but starts to suck the liquid refrigerant, and the liquid refrigerant lubricates the sliding parts such as the bearings. Increased and contributed to compressor failure.

Further, sludge is generated due to the mechanochemical reaction due to the wear, and the sludge blocks a restricting mechanism such as a capillary tube having a fixed opening area of a restrictor, which hinders a refrigerating / air-conditioning apparatus. Also, in order to prevent the restriction mechanism from being blocked by sludge, it is necessary to use a high-cost electronically controlled expansion valve or the like, which has increased the cost.

An object of the present invention is to provide a refrigeration cycle device such as a compressor or a refrigeration / air-conditioning device with high reliability. It is another object of the present invention to obtain a highly reliable refrigeration cycle device without clogging of a throttle device such as a capillary tube. It is another object of the present invention to provide a refrigeration cycle apparatus in which lubrication performance does not decrease even when an HFC refrigerant is used in a refrigeration cycle. Another object is to obtain an inexpensive refrigeration cycle device.

[0011]

According to a first aspect of the present invention, there is provided a refrigeration cycle apparatus comprising a compressor having an oil sump inside a container and having a refrigerating machine oil in the oil sump, and a compressor discharged from the compressor. A refrigeration cycle is constituted by a condenser for condensing the refrigerant, an expansion device for expanding the condensed refrigerant, and an evaporator for evaporating the expanded refrigerant.
A refrigerating machine oil that uses a C-based refrigerant and has a density reversal temperature at which the density of the refrigerating machine oil is larger than the liquid density of the refrigerant is lower than the lower limit temperature of the condensing temperature operated in the refrigerating cycle. .

A refrigeration cycle apparatus according to a second aspect of the present invention has a lower limit of the condensing temperature of 30 ° C.

A refrigeration cycle apparatus according to a third aspect of the present invention uses refrigeration oil having a density reversal temperature of less than 30 ° C.

A refrigeration cycle apparatus according to a fourth aspect of the present invention has a compressor having an oil sump in a container and holding refrigerating machine oil in the oil sump, and a condenser for condensing refrigerant discharged from the compressor. And an expansion device that expands the condensed refrigerant, and an evaporator that evaporates the expanded refrigerant constitutes a refrigeration cycle, uses an HFC-based refrigerant as the refrigerant, and has a higher density of the refrigerating machine oil than the liquid density of the refrigerant. The refrigerating machine oil has a higher density reversal temperature than the lower limit of the evaporation temperature operated in the refrigeration cycle.

In a refrigeration cycle apparatus according to a fifth aspect of the present invention, the lower limit of the evaporating temperature is -20.degree.

A refrigeration cycle apparatus according to a sixth aspect of the present invention uses a refrigerating machine oil having a density reversal temperature of less than -20 ° C.

A refrigeration cycle apparatus according to a seventh aspect of the present invention is a compressor having an oil sump inside the container and holding refrigerating machine oil in the oil sump, and a condenser for condensing the refrigerant discharged from the compressor. And a throttling device that decompresses the condensed refrigerant, and an evaporator that evaporates the depressurized refrigerant, constitutes a refrigeration cycle, uses an HFC-based refrigerant as the refrigerant, and has a higher density of the refrigerating machine oil than the liquid density of the refrigerant. The compressor is operated such that the temperature of the oil reservoir of the compressor becomes higher with respect to the density reversal temperature at which the temperature becomes larger.

A refrigeration cycle apparatus according to an eighth aspect of the present invention is provided with a heating means for heating an oil reservoir of a compressor having refrigerating machine oil therein.

A refrigeration cycle apparatus according to a ninth aspect of the present invention uses a high-pressure shell type compressor as the compressor.

[0020] A refrigeration cycle apparatus according to a tenth aspect of the present invention includes a compressor, a condenser, a high-pressure side expansion device, a receiver,
A low-pressure side expansion device and an evaporator are sequentially connected to form a refrigeration cycle, an HFC-based refrigerant is used as a refrigerant, and the density reversal temperature at which the density of the refrigerating machine oil is larger than the liquid density of the refrigerant is higher than that of the condenser. This uses a refrigerating machine oil having a condensation temperature lower than the lower limit.

A refrigeration cycle apparatus according to an eleventh aspect of the present invention uses HFC32 as a refrigerant.

The refrigeration cycle apparatus according to the twelfth aspect of the present invention uses a hard alkylbenzene-based refrigerating machine oil, an ester-based refrigerating machine oil, or an ether-based refrigerating machine oil as the refrigerating machine oil.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram illustrating an example of a refrigeration cycle device that is incorporated in a refrigeration / air-conditioning device such as an air conditioner, a refrigerator, a freezer, or the like and that forms a refrigeration cycle according to the first embodiment. In the figure, 1 is a compressor,
Reference numeral 8 denotes a four-way valve, and reference numeral 2 denotes a first heat exchanger. In the case of an air conditioner or the like, it acts as a condenser during cooling, and acts as an evaporator during heating. Reference numerals 3b and 3c denote a throttle mechanism such as a capillary tube, and 6 denotes a receiver, which can store excess refrigerant. Reference numeral 4 denotes a second heat exchanger, which acts as an evaporator during a cooling operation (solid arrow) in the case of an air conditioner or the like, and acts as a condenser during a heating operation (dotted arrow).

During a cooling operation in an air conditioner or the like, the compressor 1, the four-way valve 8, the first heat exchanger (acting as a condenser) 2, and the throttle mechanism 3b as indicated by solid arrows in the drawing. , The receiver 6, the throttle mechanism 3c, and the second heat exchanger (acting as an evaporator) 4 are sequentially connected by pipes or the like to form a closed refrigeration cycle. During the heating operation, the compressor 1, the four-way valve 8, the second heat exchanger (acting as a condenser) 4, the throttle mechanism 3c,
The receiver 6, the throttle mechanism 3b, and the first heat exchanger (acting as an evaporator) 2 are sequentially connected by a pipe or the like to form a closed refrigeration cycle.

In the compressor 1, a refrigerating machine oil 10 is sealed in an oil reservoir 1a provided in a closed container 1j.
Reference numeral 1c denotes a compression mechanism for compressing the refrigerant in a scroll or rotary type, etc., and 1b denotes an oil pump.
e. 1d is a motor rotor, 1h is a motor stator, 1m is a suction muffler, 1g is a suction pipe,
1f is a discharge pipe.

Here, when the compatible oil is used, the refrigerating machine oil 10 in which the refrigerant is dissolved is present in the oil reservoir 1a, and when the incompatible oil is used, only the refrigerating machine oil 10 or the refrigerating machine oil 1 is used.
A state in which 0 and the liquid refrigerant are separated exists in the oil reservoir 1a. The oil pump 1b draws up the refrigerating machine oil 10 or the mixed liquid of the refrigerating machine oil 10 and the refrigerant accumulated in the oil sump 1a,
The sucked refrigeration oil 10 or the mixed liquid of the refrigeration oil 10 and the refrigerant lubricates sliding parts such as bearings, and then the oil reservoir 1a
Returned to

At this time, during the cooling operation, a part of the refrigerating machine oil 10 is discharged from the discharge pipe 1f into the refrigerating cycle together with the refrigerant compressed in the compression mechanism 1c. These refrigerant and refrigerating machine oil 10 are used as a first heat exchanger (condenser).
2. Compressor suction pipe 1 after circulating through throttle mechanism 3b, receiver 6, throttle mechanism 3c, and second heat exchanger (evaporator) 4.
g is sucked into the compressor 1 again. In the case of the heating operation, after circulating through the second heat exchanger (condenser) 4, the throttle mechanism 3c, the receiver 6, the throttle mechanism 3b, and the first heat exchanger (evaporator) 2, from the compressor suction pipe 1g. It is sucked into the compressor 1 again.

The refrigerant used in the refrigeration cycle has conventionally used HCFC22. However, since it has an adverse effect on the global environment such as destruction of the ozone layer, the present invention uses an HFC-based refrigerant which does not destroy the ozone layer. I am trying to do it. In the present embodiment, HFC32 simple refrigerant is used as the refrigerant. This is because, when the HFC32 refrigerant is used alone in the refrigeration cycle, the pressure loss is small and the performance of the refrigeration cycle is improved under the same temperature conditions as compared with the case where the mixed refrigerant is used.

Normally, when the temperature is low, the density of the liquid refrigerant is higher than the density of the refrigerating machine oil. However, as the temperature increases, the density of the liquid refrigerant decreases more than the density of the refrigerating machine oil decreases. Therefore, there is a temperature at which the density of the refrigerating machine oil is higher than the density of the liquid refrigerant and the density is reversed. The temperature at which the density reverses is hereinafter referred to as the density reverse temperature.

Here, in the refrigeration cycle apparatus, it is desirable that the temperature of the oil reservoir 1a of the compressor 1 is always higher than the density inversion temperature. If the refrigerating machine oil is used in a temperature range greater than the liquid refrigerant density, the refrigerating machine oil is always located below even if the refrigerating machine oil and the liquid refrigerant are separated. High-concentration refrigeration oil can be supplied to bearings, etc. by sucking only machine oil, so lubrication performance is greatly improved and reliability is higher than when liquid refrigerant is sucked and liquid refrigerant is supplied to the bearings. A compressor and a refrigeration cycle device can be obtained. Therefore, in the present invention, the refrigeration cycle is operated by, for example, adjusting the intake gas temperature so that the temperature of the oil reservoir 1a of the compressor 1 becomes equal to or higher than the density reversal temperature.

The same effect as described above can be obtained by selecting and using a refrigerating machine oil having a density shown in FIG. 2 with respect to the refrigerant. FIG. 2 is a diagram showing the relationship between the respective densities of the used refrigerant and the refrigerating machine oil with respect to the temperatures. The horizontal axis represents the temperature, and the vertical axis represents the densities of the refrigerant and the refrigerating machine oil. In the present invention, as shown in FIG. 2, a refrigerating machine oil is used in which the density of the refrigerating machine oil is higher than the density of the liquid refrigerant at a temperature lower than the lower limit of the condensing temperature used in the refrigeration cycle. I am trying to do it. That is, the refrigerating machine oil having a density reversal temperature at which the density of the refrigerating machine oil is higher than the density of the liquid refrigerant is lower than the lower limit of the condensing temperature is used. The refrigerator oil shown in the figure is an example of a polyol ester oil, and the density reversal temperature for HFC32 refrigerant is about 21 ° C., which is lower than the lower limit of the condensing temperature of 30 ° C.

Therefore, within the operating range of the refrigeration cycle apparatus, the temperature of the oil sump in the compressor 1 and the temperature of the receiver 6 are higher than the condensing temperature in a normal operation state. The density is larger than the density, and even if the refrigerating machine oil and the liquid refrigerant are separated, the refrigerating machine oil is always located below, so that the liquid refrigerant is not sucked from the tip 6c of the outlet pipe 6b of the oil pump 1b or the receiver 6, Only the refrigerating machine oil can be supplied to the bearing and the like, and a highly reliable compressor and refrigerating cycle device can be obtained.

In this embodiment, the density inversion temperature is 30 ° C.
Try to use less than refrigeration oil. Here, the reason why the density reversal temperature is set to less than 30 ° C. is that the lower limit of the condensing temperature of a general refrigeration cycle is usually 3 as shown in FIG.
0 ° C., because it was desired to lower the lower limit of the condensing temperature to 30 ° C. FIG. 3 is a diagram illustrating an operation range of a general refrigeration cycle device, in which the horizontal axis represents the evaporation temperature and the vertical axis represents the condensation temperature. As shown in the figure, in a normal air conditioner or the like, the lower limit of the condensing temperature in the operation range of the refrigeration cycle is set to 30 ° C.

Therefore, in the case of the high-pressure shell type compressor, the pressure inside the closed casing 1j is the discharge pressure and the discharge temperature, and the temperature of the oil reservoir 1a is also higher than the condensing temperature. Therefore, if the density reversal temperature is set to less than 30 ° C., the temperature of the oil reservoir 1a becomes 30 ° C. or more, which is the lower limit of the condensing temperature, so that the density of the refrigerating machine oil is higher than the density of the liquid refrigerant, and Since the refrigerating machine oil 10 is heavier than the refrigerating machine oil and is located below, the refrigerating machine oil having a high concentration is sucked up from the oil pump 1b, and the bearing lubricity is improved.

Further, in the low-pressure shell type compressor, the temperature of the oil reservoir 1a is maintained for ten and several minutes after the start-up in a state where the refrigerant is laid in the oil reservoir 1a and in a normal operation state other than a transient operation such as a defrost operation. Is about 30 ° C. or more. Therefore, in a normal operation state other than the transient operation, if the density reversal temperature is set to less than 30 ° C., the refrigerating machine oil 10 is almost always heavier than the liquid refrigerant, and a high-concentration refrigerating machine oil is supplied from the oil pump 1b. It is sucked up and bearing lubricity is improved.

The refrigerating machine oil 10 is, for example, a polyol ester oil, a polyvinyl ether oil, a hard alkylbenzene oil, or the like, and is adjusted to have a density larger than that of the HFC32 liquid refrigerant at 30 ° C. Here, the hard alkylbenzene oil is incompatible with the HFC32 refrigerant. Polyol ester oils and polyvinyl ether oils are compatible with other HFC refrigerants, but have low compatibility with HFC32 refrigerants. The liquid refrigerant and the refrigerating machine oil are separated from each other in oil form to form respective layers. In other words, the commonly used low-cost refrigerating machine oil 10 for HFC refrigerant requires that the HFC32 refrigerant be treated as an incompatible oil in a combination of the HFC32 single refrigerant, so that the present invention is effective. Become.

Here, the behavior of the refrigerant and the refrigerating machine oil 10 inside the compressor 1 will be described in detail. When the compressor is started, the load on the compressor increases, and the heat generated in the motor unit and the compression unit increases. Therefore, the temperature of the oil reservoir 1a exceeds 30 ° C. in a steady operation state. At this time, when the liquid refrigerant is present in the oil reservoir 1a, the refrigerant oil and the liquid refrigerant are separated. However, since the density of the refrigerant oil is higher than the density of the liquid refrigerant, the refrigerant oil layer is located below the liquid refrigerant layer. Located, the oil pump 1b always sucks high concentration refrigerating machine oil. If there is no liquid refrigerant, only the refrigerating machine oil is naturally drawn from the oil pump 1b.

Therefore, when the load on the compressor is large, the sliding parts such as the bearings can be lubricated with the refrigerating machine oil 10 with little dilution by the refrigerant, so that the sliding parts are less worn and the sliding parts are less likely to seize. High compressor and refrigeration cycle equipment can be obtained. In addition, since the wear of the sliding part is small,
The amount of sludge generated by the mechanochemical reaction due to wear is small, and the amount of sludge attached to the throttle mechanisms 3b and 3c having a fixed throttle opening such as a capillary tube is also reduced. Therefore, a throttle mechanism 3 such as a capillary tube is used.
Since there is no blockage of b and 3c, it is possible to use even a capillary tube with a constant throttle opening, and it is not necessary to use a high-cost throttle mechanism such as an electronically controlled expansion valve, and it is low cost and highly reliable. A refrigeration cycle device can be obtained.

Further, when the compressor 1 is of a high-pressure shell type, since the inside of the closed vessel 1j has a high-temperature discharge gas atmosphere and the temperature in the oil reservoir 1a exceeds 30 ° C. immediately after starting,
Sliding parts such as bearings are always lubricated with the refrigerating machine oil 10 that is less diluted by the refrigerant. Therefore, the reliability of sliding parts such as bearings of the compressor 1 is improved as compared with the low-pressure shell type compressor,
A highly reliable compressor and refrigeration cycle device can be obtained.

A high-pressure shell type compressor is used as the compressor 1, HFC32 simple refrigerant is used as the refrigerant, and the refrigerant oil 10 is used.
When hard alkylbenzene oil, which is an incompatible oil, is used, the compressor 1 is always in a high-temperature and high-pressure discharge gas atmosphere while the compressor 1 is in operation.
The temperature of the refrigerating machine oil 10 in a is in a superheated state higher than the saturation temperature, and is in a state of a superheated gas in which no liquid refrigerant exists in the oil reservoir 1a. Therefore, even when hard alkylbenzene oil, which is a completely incompatible oil, is used as the HFC32 refrigerant, sliding parts such as bearings are lubricated with the refrigerating machine oil 10 with extremely little dilution by the refrigerant during normal operation or overload operation. Therefore, a highly reliable compressor and refrigeration cycle device with small wear of the sliding portion can be obtained.

In the case of polyol ester oil, H
Although it shows characteristics almost incompatible with FC32 simple refrigerant, it is not completely incompatible oil but 10% in HFC32 liquid refrigerant.
About 20% melts. Therefore, even when the compressor 1 is stopped for a long period of time and the liquid refrigerant is laid in the oil reservoir 1a, the refrigeration oil 10 is dissolved in the laid liquid refrigerant by about 10 to 20%.

Therefore, even when the liquid refrigerant is started in a stagnation state, that is, at the time of the stagnation start, the lubrication state of a sliding portion such as a bearing is improved as compared with the case where hard alkylbenzene oil is used. Also, the lubricating state of the sliding parts such as bearings during normal operation is good because the lubricating oil is lubricated with the high-concentration refrigerating machine oil 10 with little refrigerant dilution, as in the case of using the hard alkylbenzene oil. Therefore, it is possible to obtain a compressor and a refrigeration cycle device in which the sliding parts such as the bearings at the time of the stagnation start-up have higher reliability.

Also, when polyvinyl ether oil is used for the refrigerating machine oil 10 in place of the polyol ester oil, the refrigerant oil dissolves in the HFC32 liquid refrigerant to the same extent as the polyol ester oil. Therefore, the reliability of the sliding portion equivalent to that of the polyol ester oil can be obtained even at the time of start-up or during normal operation. Further, polyol ester oil is liable to undergo hydrolysis degradation by reacting with a small amount of water contained in the refrigerant circuit, but polyvinyl ether oil is less susceptible to hydrolysis than polyol ester oil. A highly reliable compressor and refrigeration cycle device which generate little sludge and have a low risk of closing a throttle mechanism such as a capillary tube can be obtained.

Here, if the refrigerating cycle is stopped for a long time, the refrigerating machine oil 10 having incompatibility with the refrigerant and the liquid refrigerant are separated in the oil sump 1a of the compressor 1. Accumulate. At this time, if the temperature of the refrigeration oil 10 and the liquid refrigerant is equal to or higher than the density inversion temperature, the density of the refrigeration oil 10 is higher than the density of the liquid refrigerant, so that the refrigeration oil 10 is positioned below the liquid refrigerant. , And the vicinity of the suction port of the oil pump 1b is filled with the refrigerating machine oil 10. When the compressor 1 starts in this state, the rotor 1d of the motor and the crankshaft 1
e, the inside of the oil reservoir 1a is slightly stirred, but the oil pump 1
b shows that the refrigerating machine oil 1 has a small refrigerant dilution and a high oil concentration.
Only 0 is sucked up. Therefore, the lubrication state of the sliding parts such as the bearings is extremely good even when the refrigerant is started in a state where the refrigerant is laid down.

When the refrigerating machine oil 10 and the liquid refrigerant are separated and stored in the oil sump 1a, their temperatures are as follows:
If the temperature is equal to or lower than the density reversal temperature, since the density of the refrigerating machine oil 10 is smaller than the density of the liquid refrigerant, the refrigerating machine oil 10 is located above the liquid refrigerant and the vicinity of the suction port of the oil pump 1b is filled with the liquid refrigerant. It is. When the compressor 1 is started in this state, the oil reservoir 1a is agitated by the rotor 1d and the crankshaft 1e, so that the liquid refrigerant mixed with the refrigerating machine oil 10 as an emulsion is sucked up from the oil pump 1b, and a small amount of refrigeration is performed. The sliding parts such as bearings are lubricated by the machine oil 10.

However, since the compressor load is small immediately after the start, the bearing load is small and even if a small amount of refrigerating machine oil is mixed, the bearing is hardly damaged. After about 1 minute, the load on the compressor increases, and the temperature of the oil reservoir 1a becomes higher than the density reversal temperature due to the heat generated by the motor and the temperature of the evaporator.
Since the lubrication of the sliding portion by the high concentration refrigerating machine oil 10 starts due to the movement to the lower part a, the bearing is hardly damaged.

Therefore, a reliable refrigeration cycle with little damage to sliding parts such as bearings can be obtained even when the refrigerant is started in a state where the refrigerant is laid in the oil reservoir 1a. further,
If the compressor 1 is a high-pressure shell type compressor in which the inside of a closed vessel has a high-pressure atmosphere, the temperature of the oil reservoir 1a immediately exceeds 30 ° C. immediately after startup, so that the density and liquid The density of the refrigerant is reversed, and the sliding parts such as the bearings are lubricated with the refrigerating machine oil 10 having a high concentration. Therefore, the reliability of the sliding portion such as a bearing at the time of startup in a state where the refrigerant is laid down is further improved.

Next, the behavior of the refrigerant and the refrigerating machine oil 10 in the refrigerant circuit outside the compressor 1 will be described. Most refrigeration oil 10
Is circulated in the compressor 1 and is not discharged to the outside, but a small amount of the refrigerating machine oil 10 is discharged from the compressor discharge pipe 1f to the refrigerating cycle together with the refrigerant compressed by the compression mechanism 1c. After circulating through the condenser 2, the receiver 6, the throttle mechanism 3b, and the evaporator 4, the refrigerant and the refrigerating machine oil 10 are sucked into the compressor 1 again from the compressor suction pipe 1g. The circulating refrigeration oil 10 accumulates in the receiver 6 provided in the refrigerant circuit for storing the surplus refrigerant.

An oil return mechanism for returning the accumulated refrigerating machine oil 10 to the refrigerant circuit is provided in the receiver 6. Here, the structure of the receiver 6 is shown in FIG. FIG. 4 is a diagram showing the structure of the receiver and the state of the refrigerating machine oil. In the figure, reference numeral 6 denotes a receiver, and an inlet pipe 6a is provided in the container.
And an outlet pipe 6b are provided.
c extends to near the bottom of the container. In the receiver 6,
The temperature is intermediate between the condensing temperature and the evaporating temperature, and frequently becomes higher than 30 ° C., which is the lower limit of the condensing temperature, during steady operation. Therefore, since the temperature inside the receiver 6 is higher than the density reversal temperature (less than 30 ° C.), the density of the refrigerating machine oil 10 is almost constantly higher than that of the liquid refrigerant.
As shown in (2), the layer of the refrigerating machine oil 10 is located below the layer of the liquid refrigerant.

Here, since the tip 6c of the outlet pipe 6b of the receiver 6 is provided near the bottom of the container, the opening of the pipe is almost always filled with the refrigeration oil 10, and the refrigeration oil 10 has priority. Then, it is discharged from the receiver 6. For this reason, the refrigerating efficiency of the refrigerating machine oil 10 becomes extremely high, and a highly reliable refrigerating cycle device in which the refrigerating machine oil 10 in the compressor 1 is not depleted can be obtained.

Further, when the receiver 6 is on the high pressure side where the refrigerant is in a two-phase state, for example, a two-phase part in which the refrigerant is not completely liquefied, or when there are two condensers as shown in FIG. , When placed between the two condensers, the temperature of the receiver 6 becomes approximately the condensation temperature. FIG. 5 is a diagram illustrating a configuration of a refrigeration cycle when two condensers are present. In the figure, parts that are the same as in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted. In the figure, 2a and 2b are heat exchangers, which function as condensers. Reference numeral 6 denotes a receiver. The lower limit of the condensing temperature in the operating range is 30 ° C., and the temperature in the receiver 6 is always equal to or higher than the lower limit of the condensing temperature, and the temperature in the receiver 6 is higher than the density inversion temperature. Therefore, the layer of the refrigerating machine oil 10 always accumulates at the bottom of the receiver 6 more than the layer of the liquid refrigerant, and the oil return efficiency is further increased.

The refrigerant other than HFC32 simple refrigerant is H
FC simple refrigerant or HFC mixed refrigerant, for example, HFC
32, a mixed refrigerant of three types of HFC125 and HFC134a,
HFC125, HFC143a, HFC134a three-type mixed refrigerant, HFC32, HFC125 two-type mixed refrigerant,
The same effect can be obtained by using the HFC134a simple refrigerant or the like.

The refrigerating machine oil 10 may be a hard alkylbenzene oil which is an incompatible oil, a polyol ester oil having compatible oil properties, or a polyvinyl ether oil. In the case of a polyol ester oil or a polyvinyl ether oil, it shows compatible oil properties with respect to the HFC simple refrigerant other than the HFC32 simple refrigerant or the HFC mixed refrigerant. Although the complete separation of the refrigerant does not occur, if the temperature in the receiver 6 is equal to or higher than the density reversal temperature, there is a part with a concentrated concentration, and the part with a high concentration of the refrigerating machine oil 10 has a high concentration of the liquid refrigerant. It will be located below the part.

This is because the temperature in the receiver 6 is almost constantly higher than the density reversal temperature, and the density of the refrigerating machine oil 10 is almost constantly higher than the density of the liquid refrigerant. In this case, since the portion where the concentration of the refrigerating machine oil 10 is high gathers near the bottom surface of the receiver 6, the refrigerant having the high concentration of the refrigerating machine oil 10 is refrigerated from the opening of the outlet end 6c of the receiver outlet pipe 6b located near the bottom surface. Exhausted in the cycle. Therefore, the refrigerating efficiency of the refrigerating machine oil 10 is increased, and a highly reliable refrigerating cycle in which the refrigerating machine oil 10 in the compressor 1 is hardly depleted can be obtained.

Embodiment 2 FIG. 6 is a diagram illustrating an example of a refrigeration cycle device according to Embodiment 2 of the present invention. In the present embodiment, a means for heating the oil reservoir 1a of the compressor 1 is provided in the first embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. . FIG.
Is a heating means for heating the oil reservoir 1a of the compressor 1. The heating means 7 is of a type such as a crankcase heater that supplies heat from the outside of the compressor 1, or a current such that the compressor 1 does not start flowing through the windings of the stator 1 h to generate heat in the windings of the stator 1 h. Although there is a means for heating the inside of the compressor 1 called so-called constrained energization, other heating means may be used.

Any heating means may be provided as long as the heating means has a heating capacity enough to raise the temperature of the refrigerant / refrigerating oil 10 in the oil reservoir 1a to the density reversal temperature or higher. When the oil reservoir 1a of the compressor 1 is heated, the oil reservoir 1a is heated by a timer for a preset time (a time that can be raised to a density reversal temperature or more by an experiment or the like is set in advance) or the compressor is heated. A temperature thermostat or the like may be attached to the first oil sump 1a, and the thermostat may be used to heat the oil sump 1a of the compressor 1 so that the temperature becomes equal to or higher than the density inversion temperature.

Here, if the temperature of the oil reservoir 1a of the compressor 1 is heated by the heating means 7 to a density reversal temperature determined by the refrigerant used in the refrigeration cycle and the refrigerating machine oil at the time of stop or operation, the incompatible oil If a two-phase separation state occurs when the compressor is stopped when using a compressor, the layer of refrigerating machine oil will always be located below the layer of liquid refrigerant with a simple configuration such as a crankcase heater. In addition, the compressor oil and the refrigeration cycle device which can suck the refrigerating machine oil from the oil pump 1b and have high reliability can be obtained.

Embodiment 3 FIG. FIG. 7 is a diagram illustrating an example of a refrigeration cycle apparatus according to Embodiment 3 of the present invention. In the present embodiment, an accumulator is provided in the first embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted. An accumulator 5 is provided on the suction side of the compressor 1 in the refrigeration cycle.

In an apparatus constituting a refrigeration cycle requiring a large amount of refrigerant, such as a package air conditioner or an air conditioner for building air conditioning, an excess refrigerant such as the accumulator 5 is stored in addition to the receiver 6 described in the first embodiment. Containers may be provided. In this case, the receiver 6,
Since the refrigerating machine oil 10 circulating together with the refrigerant also accumulates in a container such as the accumulator 5, an oil return mechanism for returning oil from this container to the refrigerant circuit (compressor 1) is required.

When the container is the accumulator 5 provided on the compressor suction side, the critical melting of the refrigerating machine oil 10 becomes lower than the temperature of the liquid refrigerant / refrigerating machine oil 10 in the accumulator 5 during operation when the evaporation temperature is low. The temperature is higher,
There is a case where the liquid refrigerant and the refrigerating machine oil 10 are separated. Here, FIG. 8 and FIG. 9 are diagrams showing the density change with respect to the temperature of the liquid refrigerant and the refrigerating machine oil. In the figure, the horizontal axis represents the temperature, and the vertical axis represents the densities of the refrigerating machine oil and the liquid refrigerant. FIG.
In, for example, the HFC binary mixed refrigerant is R410A
(R125: 50%, R32: 50%) and HFC
R407C (R134a: 52%, R1
25: 25%, R32: 23%). The refrigerating machine oil is, for example, a polyol ester oil. In this case, the density reversal temperature is 43 ° C. for R410A and R407 for R410A.
C is 60 ° C, and the lower limit of the condensation temperature is 30 ° C.
Higher than ° C.

Therefore, as shown in FIG. 8, within the operating temperature range of the accumulator 5, the density of the refrigerating machine oil 10 is smaller than the density of the liquid refrigerant, and in the case of incompatible oil, as shown in FIG. The layer of the refrigerating machine oil 10 is separated from the layer of the liquid refrigerant, and the layer of the refrigerating machine oil 10 is positioned above the layer of the liquid refrigerant. FIG. 10 is a diagram showing a state of the liquid refrigerant and the refrigerating machine oil in the accumulator 5. In the figure,
The density of the refrigerating machine oil is smaller than the density of the liquid refrigerant,
FIG. 3 shows a two-phase separation state in which a layer of refrigerating machine oil is located above a layer of liquid refrigerant. Refrigeration oil 10 as in the case of FIG.
Even when complete separation of the refrigerant oil and the liquid refrigerant does not occur, there may be a case where a layer having a high concentration of the refrigerating machine oil 10 is located above a layer having a high liquid refrigerant concentration due to a density difference as shown in FIG. . FIG. 11 is a diagram showing a state of the liquid refrigerant and the refrigerating machine oil in the accumulator 5, and in FIGS. 10 and 11, 5 is an accumulator, 5a is a refrigerating machine oil accumulated in the accumulator 5 in a refrigerant circuit (compressor 1). An oil return hole for returning oil.

Therefore, as shown in FIG. 10, when the liquid refrigerant and the refrigerating machine oil 10 are separated from each other, the oil level (height) varies depending on the amount of the accumulated liquid refrigerant. When the position of the refrigerating machine oil is higher than the position of the oil return hole 5a, only the liquid refrigerant is sent from the oil return hole 5a to the refrigerant circuit, and the refrigerating machine oil of the compressor 1 runs short. FIG. 11 shows that the liquid refrigerant and the refrigerating machine oil are not separated.
Even in such a case, the oil return hole 5a is located in a portion where the liquid refrigerant concentration is high, so that most of the oil is returned by the liquid refrigerant, and the oil return efficiency is poor. When the oil return characteristics are poor, the refrigerating machine oil in the compressor is depleted and sliding parts such as bearings of the compressor may be damaged.

When the immiscible oil and the HFC refrigerant are used in combination, even if the immiscible oil is used, the extreme pressure effect of the refrigerant cannot be obtained as in the case of the immiscible oil. Because the refrigerant hardly dissolves and the refrigerant does not dilute the refrigerating machine oil 10, the oil viscosity does not decrease and lubrication is better than that of the compatible oil even under boundary lubrication, and sludge generation is reduced. For this reason, the incompatible oil is less likely to block the capillary tube or the like due to the generation of sludge than the compatible oil, and thus the incompatible oil has better lubrication performance than the compatible oil.

For example, as shown in FIG. 9, at room temperature, as the refrigerating machine oil in which the specific gravity of the refrigerating machine oil 10 becomes smaller than the specific gravity of the refrigerant, an incompatible oil such as a hard alkylbenzene oil other than the ester oil is used. In the case, when the refrigerant stagnates in the oil reservoir 1a in the compressor 1 when the compressor is stopped for a long time,
The liquid refrigerant and the refrigerating machine oil 10 are separated, and a layer of the liquid refrigerant having a large specific gravity is located below the layer of the refrigerating machine oil 10, and a portion near the suction port of the oil pump 1 b located at a lower part in the compressor 1 is filled with the liquid refrigerant. It is. When the compressor 1 is started in this state, the oil reservoir 1a is stirred by the rotor 1d and the crankshaft 1e of the motor, and a mixture of the liquid refrigerant and the refrigerating machine oil 10 in an emulsion form is sucked from the oil pump 1b. It is necessary to lubricate sliding parts such as bearings with a small amount of refrigerating machine oil 10, which causes bearing damage.

When a container such as the accumulator 5 and the receiver 6 for storing surplus refrigerant is provided, the refrigerating machine oil 10 circulating together with the refrigerant also accumulates in this container. Therefore, an oil return mechanism is required to return oil from this container to the refrigerant circuit, and an oil return hole 5a is provided as shown in FIG. Further, in the case where the refrigerating machine oil is an incompatible oil, the refrigerating machine oil and the liquid refrigerant are separated as shown in FIG. At this time, in the accumulator 5, since the density of the refrigerating machine oil is always smaller than the liquid refrigerant density within the operating temperature range in which the accumulator is used (see FIG. 9), as shown in FIG. The state is located above the liquid refrigerant layer.

In the receiver 6 provided between the condenser 2 and the evaporator 4, the density of the refrigerating machine oil almost constantly decreases, so that the refrigerating machine oil layer is located above the liquid refrigerant layer. Since the amount of the liquid refrigerant changes according to the operating conditions of the refrigeration cycle, the position (height) of the refrigeration oil layer also changes according to the operating conditions.

Here, FIG. 10 shows the case where the accumulator 5 is used as a container. FIG. 12 shows the positional relationship between the refrigerating machine oil layer and the liquid refrigerant layer when the receiver 6 is used. FIG. 12 is a diagram illustrating a state of the refrigerating machine oil and the liquid refrigerant in the receiver 6, and illustrates a state in which the layer of the refrigerating machine oil and the layer of the liquid refrigerant are separated. In the figure, 6a is an inlet pipe, 6b is an outlet pipe, and 6c is a tip of the outlet pipe.
In order to return oil from the container to the refrigerant circuit, the tip 6c of the outlet pipe 6b is provided near the lower end in the container as shown in FIG.

Therefore, if the refrigerating machine oil layer is positioned below the liquid refrigerant layer, the refrigerating machine oil is sucked from the tip 6c, so that there is no problem.
As shown in FIG. 11, the refrigerating machine oil and the liquid refrigerant are separated. At this time, in the receiver 6, the density of the refrigerating machine oil is smaller than the liquid refrigerant density under most of the temperature conditions within the operating temperature range in which the receiver is used (see FIG. 9), and as shown in FIG. The refrigerator oil layer is located above the liquid refrigerant layer.

In either case of the accumulator 5 or the receiver 6, the oil return hole 5a and the outlet pipe tip 6c which should always be located between the refrigerating machine oil layers are within the operating temperature range in which the accumulator 5 or the receiver 6 is used. Is located in the liquid refrigerant layer in most temperature zones. In this case, since only the liquid refrigerant is returned to the compressor 1, the oil return efficiency is reduced. In such a state where the oil return efficiency is low, the refrigerating machine oil in the oil reservoir 1a is depleted, and there is a possibility that the sliding parts such as bearings may be damaged.

Since the height position of the refrigerating machine oil layer also fluctuates due to the fluctuation of the liquid refrigerant layer, it was difficult to determine the positions of the oil return hole 5a and the outlet pipe tip 6c, and the oil return mechanism could not be designed. For this reason, when the incompatible oil and the HFC refrigerant are used in combination, the amount of the refrigerant required for the refrigeration cycle is small and the refrigerating machine oil 10 accumulates the surplus refrigerant that accumulates like the accumulator 5 or the receiver 6. Only room air conditioners and refrigerators that do not require a simple container were used. Therefore, by providing the heating means as described in the second embodiment also in the accumulator 5 and the receiver 6, the problem described in FIGS. 8 and 9 can be solved. That is, by providing the accumulator 5 and the receiver 6 with the heating means as described in the first embodiment,
What is necessary is just to heat the refrigerant used for the refrigeration cycle and the refrigerating machine oil to the density reversal temperature or higher so that the refrigerating machine oil layer is always positioned below the liquid refrigerant layer.

Here, a method other than providing the heating means will be described with reference to FIG. FIG. 13 is a diagram showing the relationship between the respective densities of the used refrigerant and the refrigerating machine oil with respect to the temperature. The horizontal axis represents the temperature, and the vertical axis represents the density of the refrigerant and the refrigerating machine oil. In the present invention, as shown in FIG. 13, a refrigerating machine oil is used in which the density of the refrigerating machine oil is higher than the density of the liquid refrigerant at a temperature lower than the lower limit temperature of the evaporation temperature used in the refrigerating cycle. I am trying to do it. That is, the refrigerating machine oil having a density reversal temperature at which the density of the refrigerating machine oil is higher than the density of the liquid refrigerant is lower than the lower limit of the evaporation temperature is used.

Therefore, if refrigerating machine oil having a density reversal temperature lower than the lower limit of the evaporation temperature is used, the oil reservoir 1a of the compressor 1 can be provided without providing the heating means 7 such as the crankcase heater described in the second embodiment. Since the refrigerating machine oil 10 is always located below the liquid refrigerant in the inside of the accumulator 5 and the receiver 6, the refrigerating machine oil having a high oil concentration can be supplied to the bearing portion, and a highly reliable compressor and refrigerating cycle with a simple configuration. A device is obtained. In addition, since it is not necessary to separately provide a heating means such as a crankcase heater, a highly reliable compressor and refrigeration cycle apparatus that can reduce the time required for mounting the heating means at low cost can be obtained.

In this embodiment, the density reversal temperature is −20.
Refrigerator oil below ℃ is used. here,
The density reversal temperature is set to less than -20 ° C because the lower limit of the evaporation temperature of a general refrigeration cycle is -20 ° C as shown in FIG. 3, and the lower limit of the evaporation temperature is -20 ° C.
Because I wanted to lower it. As shown in the figure, in a normal air conditioner or the like, the lower limit of the evaporation temperature in the operation range of the refrigeration cycle is set to -20 ° C.

Therefore, in the case of the high-pressure shell type compressor, the pressure inside the closed casing 1j is the discharge pressure and the discharge temperature, and the temperature of the oil reservoir 1a is higher than the evaporation temperature. Therefore, if the density reversal temperature is set to less than −20 ° C., the temperature of the oil reservoir 1a becomes equal to or higher than the lower limit of the evaporating temperature of −20 ° C., so that the density of the refrigerating machine oil is higher than the density of the liquid refrigerant, Since the refrigerating machine oil 10 is heavier than the liquid refrigerant and located below, the refrigerating machine oil having a high concentration is sucked up from the oil pump 1b, and the bearing lubricity is improved.

Also in the low-pressure shell type compressor, the temperature of the oil reservoir 1a is not lower than the lower limit of the evaporation temperature, even when the refrigerant is laid in the oil reservoir 1a and the transient operation such as the defrost operation is considered. This is because the temperature becomes -20 ° C or more. Therefore, if the density reversal temperature is set to a temperature lower than the evaporation temperature lower limit temperature of −20 ° C., the refrigeration oil 10 will always be more liquefied than the liquid refrigerant even in most operation states such as a transient operation state and a steady operation state. It is heavier and the refrigerating machine oil having a high concentration is sucked up from the oil pump 1b, so that a highly reliable compressor or refrigeration cycle device in which the bearing lubrication performance does not decrease can be obtained.

[0076]

The refrigeration cycle apparatus according to the first aspect of the present invention has a compressor having an oil sump inside the container and holding the refrigerating machine oil in the oil sump, and condensing the refrigerant discharged from the compressor. A condenser, an expansion device for expanding the condensed refrigerant,
A refrigerating cycle is constituted by an evaporator for evaporating the expanded refrigerant, and an HFC-based refrigerant is used as the refrigerant, and the density reversal temperature at which the density of the refrigerating machine oil is larger than the liquid density of the refrigerant is operated in the refrigeration cycle. Since the refrigerating machine oil having a temperature lower than the lower limit temperature of the condensing temperature is used, the oil sump in the compressor 1 and the temperature of the receiver 6 become equal to or higher than the condensing temperature in a normal operation state. Liquid refrigerant is not sucked from the tip 6c of the outlet pipe 6b, and a highly reliable compressor and refrigeration cycle device can be obtained.

In the refrigeration cycle apparatus according to the second aspect of the present invention, since the lower limit of the condensing temperature is set at 30 ° C., the density of the refrigerating machine oil is higher than that of the liquid refrigerant, and the refrigerating machine oil 10 has a higher density than the liquid refrigerant. Is heavier and located below, and a high concentration of refrigerating machine oil is sucked up from the oil pump, so that a highly reliable compressor and refrigeration cycle device with improved bearing lubrication can be obtained.

In the refrigeration cycle apparatus according to the third aspect of the present invention, since the refrigerating machine oil having a density reversal temperature of less than 30 ° C. is used, the refrigerating machine oil is substantially heavier than the liquid refrigerant. A highly reliable compressor and refrigeration cycle device in which high-concentration refrigerating machine oil is sucked up and bearing lubricity is improved can be obtained.

A refrigeration cycle apparatus according to a fourth aspect of the present invention has a compressor having an oil sump inside the container and holding refrigerating machine oil in the oil sump, and a condenser for condensing the refrigerant discharged from the compressor. And an expansion device that expands the condensed refrigerant, and an evaporator that evaporates the expanded refrigerant constitutes a refrigeration cycle, uses an HFC-based refrigerant as the refrigerant, and has a higher density of the refrigerating machine oil than the liquid density of the refrigerant. Refrigeration oil having a lower density reversal temperature than the lower limit of the evaporation temperature operated in the refrigeration cycle is used. Therefore, even if the heating means 7 such as a crankcase heater is not provided, the oil in the oil sump of the compressor can be obtained. In the accumulators and receivers, the refrigerating machine oil is always located below the liquid refrigerant, and can supply the refrigerating machine oil with a high oil concentration to the bearings. Le device is obtained.

In the refrigeration cycle apparatus according to the fifth aspect of the present invention, since the lower limit of the evaporation temperature is -20 ° C., the refrigerating machine oil is always heavier than the liquid refrigerant even in a transient operation state or a steady operation state. In addition, a high concentration of refrigerating machine oil is sucked from the oil pump, and a highly reliable compressor or refrigerating cycle device in which bearing lubrication performance does not decrease can be obtained.

The refrigeration cycle apparatus according to the seventh aspect of the present invention uses refrigeration oil having a density reversal temperature of less than -20 ° C., so that the liquid refrigerant is always kept in a transient operation state or a steady operation state. The refrigerating machine oil is heavier than the refrigerating machine oil, and the refrigerating machine oil having a high concentration is sucked up from the oil pump, so that a highly reliable compressor or refrigerating cycle device in which the bearing lubrication performance does not decrease can be obtained.

A refrigeration cycle apparatus according to a seventh aspect of the present invention has a compressor having an oil sump inside the container and holding refrigerating machine oil in the oil sump, and a condenser for condensing the refrigerant discharged from the compressor. And a throttling device that decompresses the condensed refrigerant, and an evaporator that evaporates the depressurized refrigerant, constitutes a refrigeration cycle, uses an HFC-based refrigerant as the refrigerant, and has a higher density of the refrigerating machine oil than the liquid density of the refrigerant. The compressor is operated so that the temperature of the oil sump of the compressor becomes higher with respect to the density reversal temperature, which is larger than that of the case where the liquid refrigerant is sucked and supplied to the bearing. The lubrication performance is greatly improved, and a refrigeration cycle apparatus having high reliability and good lubrication of sliding parts such as bearings of a compressor can be obtained.

In the refrigeration cycle apparatus according to the eighth aspect of the present invention, since the heating means for heating the oil sump of the compressor having the refrigerating machine oil therein is provided, the refrigeration cycle apparatus can be installed at low cost and the installation time of the heating means can be shortened. A highly efficient compressor and refrigeration cycle device can be obtained.

The refrigeration cycle apparatus according to the ninth aspect of the present invention uses a high-pressure shell type compressor as the compressor. Since the temperature exceeds the lower limit of condensation temperature,
Sliding parts such as bearings are always lubricated with refrigerating machine oil with little dilution by refrigerant, and the reliability of sliding parts such as bearings of compressors is improved compared to compressors of low-pressure shell type. A refrigeration cycle device can be obtained.

The refrigeration cycle apparatus according to the tenth aspect of the present invention comprises a compressor, a condenser, a high-pressure side throttle device, a receiver,
A low-pressure side expansion device and an evaporator are sequentially connected to form a refrigeration cycle, an HFC-based refrigerant is used as a refrigerant, and the density reversal temperature at which the density of the refrigerating machine oil is larger than the liquid density of the refrigerant is higher than that of the condenser. The use of refrigerating machine oil with a condensing temperature below the lower limit reduces the amount of sludge adhering to the throttle mechanism with a fixed throttle opening such as a capillary tube, and does not cause blockage of the throttle mechanism. However, there is no need to use a costly throttle mechanism such as an electronically controlled expansion valve, and a low-cost and highly reliable refrigeration cycle apparatus can be obtained.

Since the refrigeration cycle apparatus according to the eleventh aspect of the present invention uses HFC32 as the refrigerant, the pressure loss is smaller and the performance of the refrigeration cycle is lower than in the case of using the mixed refrigerant under the same temperature condition. An improved high-performance refrigeration cycle device can be obtained.

The refrigeration cycle apparatus according to the twelfth aspect of the present invention uses a hard alkylbenzene-based refrigeration oil, an ester-based refrigeration oil, or an ether-based refrigeration oil as the refrigeration oil. Even with this, it is possible to obtain a compressor and a refrigeration cycle device with even higher reliability of sliding parts such as bearings at the time of start-up.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a refrigeration cycle device constituting a refrigeration cycle according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating a relationship between a density and a temperature of a refrigerant and a refrigerating machine oil used according to Embodiment 1 of the present invention.

FIG. 3 is a diagram illustrating an operation range of a general refrigeration cycle device according to Embodiment 1 of the present invention.

FIG. 4 is a diagram illustrating a structure of a receiver and a state of refrigerating machine oil according to Embodiment 1 of the present invention.

FIG. 5 is a diagram illustrating a configuration of a refrigeration cycle when the condenser according to Embodiment 1 of the present invention is divided into two.

FIG. 6 is a diagram showing an embodiment of a refrigeration cycle apparatus according to Embodiment 2 of the present invention. .

FIG. 7 is a diagram showing an embodiment of a refrigeration cycle apparatus according to Embodiment 3 of the present invention. .

FIG. 8 is a diagram illustrating a density change with respect to a temperature of a liquid refrigerant and a refrigerating machine oil according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a density change with respect to the temperature of the liquid refrigerant and the refrigerating machine oil according to the third embodiment of the present invention.

FIG. 10 is a diagram illustrating a state of a liquid refrigerant and refrigerating machine oil in an accumulator 5 according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating a state of a liquid refrigerant and refrigerating machine oil in an accumulator 5 according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating states of refrigeration oil and liquid refrigerant in a receiver 6 according to the third embodiment of the present invention.

FIG. 13 is a diagram illustrating the relationship between the density of the refrigerant used and the temperature of the refrigerating machine oil according to the third embodiment of the present invention.

FIG. 14 is a diagram illustrating an example of a conventional refrigeration cycle.

[Explanation of symbols]

1 compressor, 1a oil sump, 1b oil pump, 1c compression mechanism, 1d rotor, 1e crankshaft, 1f discharge pipe, 1g suction pipe, 1h stator, 1m suction muffler, 2nd heat exchanger, 3a throttle mechanism, 3b, 3c
Restrictor, 4th heat exchanger, 5 accumulator, 5a
Oil return hole, 6 receiver, 6a inlet pipe, 6b outlet pipe, 6c outlet pipe tip, 7 crankcase heater, 8 four-way valve, 10 refrigeration oil.

Claims (12)

[Claims] 1. A compressor having an oil reservoir inside a container and having refrigerating machine oil in the oil reservoir, a condenser for condensing a refrigerant discharged from the compressor, and an expansion for expanding the condensed refrigerant. A device and an evaporator for evaporating the expanded refrigerant constitute a refrigeration cycle, and an HFC-based refrigerant is used as the refrigerant. A refrigeration cycle apparatus using refrigeration oil having a temperature lower than a lower limit temperature of a condensing temperature operated in the refrigeration cycle. 2. The refrigeration cycle apparatus according to claim 1, wherein the lower limit of the condensing temperature is 30 ° C. 3. The refrigeration cycle apparatus according to claim 1, wherein a refrigerating machine oil having a density reversal temperature of less than 30 ° C. is used. 4. A compressor having an oil sump inside the container and holding refrigerating machine oil in the oil sump, a condenser for condensing a refrigerant discharged from the compressor, and an expansion for expanding the condensed refrigerant. A device and an evaporator for evaporating the expanded refrigerant constitute a refrigeration cycle, and an HFC-based refrigerant is used as the refrigerant. A refrigeration cycle apparatus using refrigeration oil having a temperature lower than a lower limit temperature of an evaporation temperature operated in the refrigeration cycle. 5. The refrigeration cycle apparatus according to claim 4, wherein the lower limit of the evaporation temperature is −20 ° C. 6. The refrigeration cycle apparatus according to claim 4, wherein a refrigerating machine oil having a density reversal temperature lower than −20 ° C. is used. 7. A compressor having an oil sump inside the container and holding refrigerating machine oil in the oil sump, a condenser for condensing the refrigerant discharged from the compressor, and a restrictor for decompressing the condensed refrigerant. A refrigeration cycle is constituted by the apparatus and an evaporator for evaporating the depressurized refrigerant, and the HFC-based refrigerant is used as the refrigerant, and the density of the refrigeration oil is higher than the liquid density of the refrigerant. A refrigeration cycle apparatus wherein the compressor is operated such that the temperature of the oil reservoir of the compressor becomes higher than the temperature. 8. The refrigeration cycle apparatus according to claim 1, further comprising heating means for heating the oil reservoir of the compressor having refrigeration oil therein. 9. The refrigeration cycle apparatus according to claim 1, wherein a high-pressure shell type compressor is used as the compressor. 10. A refrigeration cycle is configured by sequentially connecting a compressor, a condenser, a high-pressure side expansion device, a receiver, a low-pressure side expansion device, and an evaporator, and using an HFC-based refrigerant as a refrigerant,
A refrigeration cycle apparatus using a refrigerating machine oil having a density reversal temperature at which the density of the refrigerating machine oil is higher than the liquid density of the refrigerant is equal to or lower than a lower limit of the condensation temperature of the condenser. 11. The refrigeration cycle apparatus according to claim 1, wherein HFC32 is used as a refrigerant. 12. The refrigeration cycle apparatus according to claim 1, wherein a hard alkylbenzene-based refrigerating machine oil, an ester-based refrigerating machine oil, or an ether-based refrigerating machine oil is used as the refrigerating machine oil.