JP2000130332A - Horizontal hermetic compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of leak caused by the electrical insulating property of the ice machine oil, by horizontally accomodating a machine part and a motor part for driving the machine part in a hermetic casing, and sealing a HFC refrigerant and the ester ice machine oil having a specified volume resistance value into the sealed casing. SOLUTION: A machine part and a motor part 10 for driving the machine part are horizontally accomodated in a hermetic casing, and a HFC refrigerant 17 and an ester ice machine oil 12 of 1013 Ωcm or more of volume resistance value are sealed in the hermetic casing. A shaft 2 is rotated by the torque of the motor part 10 to move a piston 5, whereby the refrigerant in a compression chamber 7 formed by a sub-bearing 3, a bearing 4 and a cylinder 6 is compressed. When a temperature of a compressor is increased by the heat generated by the compression of the refrigerant, the heat generated in the motor part 10, or the like, the ester ice machine oil and the refrigerant HFC-134a are gradually dissolved, so that the ester ice machine oil and the refrigerant HFC-134a are finally dissolved and two-layered separation is resolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal hermetic compressor using an HFC-based refrigerant and a refrigeration system having the horizontal hermetic compressor.

[0002]

2. Description of the Related Art In recent years, chlorofluorocarbon (hereinafter referred to as C)
Attention has been focused on environmental problems such as ozone layer depletion and global warming caused by the influence of FC. From this point of view, reducing the amount of CFC used as a refrigerant has become a very important theme. Conventionally, fully halogenated carbon compounds that have been used as CFCs contain at least one hydrogen.
Substitution is being attempted with halogenated carbon compounds containing more than one.

More specifically, dichlorodifluoromethane (hereinafter referred to as CFC-12) which is a typical refrigerant
Is an alternative substance to CFC, and various improvements have been made to replace it with 1,1,1,2-tetrafluoroethane (hereinafter referred to as HFC-134a) or the like which has little effect on ozone depletion.

[0004] For example, DuPo issued in October 1978
According to Research Disclosure of nt, HFC-134a is poorly compatible with any conventional oils, causes two-phase separation in all temperature ranges, and is only soluble in glycol-based oils only. However, subsequent studies have shown that it can also be dissolved in special ester-based oils. For example, in U.S. Pat. No. 4,851,144, a refrigerating machine oil in which an ester type and a glycol type are mixed is used as a refrigerant HFC.
-134a.

However, many ester refrigerating machine oils are hardly soluble in the refrigerant HFC-134a and cause two-layer separation, and the critical melting temperature is high. However, these ester refrigerating machine oils have higher reliability and lubricity than special ester refrigerating machine oils having a low critical solution temperature.

When the refrigerant and the refrigerating machine oil are separated into two layers, the refrigerating machine oil is located above the refrigerant because of its low specific gravity. Conversely, the refrigerant is located on the lower side.

[0007] It has also been found that the refrigerant HFC-134a contains a large number of hydrogen atoms, so that it is essentially easy to conduct electricity, and the electrical insulation required for the hermetic compressor is very poor.

FIG. 2 is a sectional view of a conventional hermetic compressor. In FIG. 2, reference numeral 1 denotes a mechanical unit, which comprises a shaft 2, a sub bearing 3, a bearing 4, a piston 5, and a cylinder 6. The shaft 2, the sub bearing 3, the bearing 4, the piston 5 and the cylinder 6 form a compression chamber 7. 8 is an oil supply pipe,
A mixture of refrigerant HFC-134a and ester-based refrigerating machine oil is supplied to the sliding surface. Reference numeral 10 denotes a motor unit. Also 11
Is a metallic closed casing that houses the mechanical unit 1 and the motor unit 10 described above.

[0009]

In the hermetic compressor constructed as described above, the shaft 2 is connected to the motor 1
The piston 5 is rotated by the rotational force of 0 to move the piston 5 and compress the refrigerant in the compression chamber 7 formed by the sub-bearing 3, the bearing 4 and the cylinder 6. The compressed refrigerant is cooled in the refrigeration system and returns to the compressor again.

A small compressor as shown in FIG.
In recent years, the horizontal type, that is, the mechanical unit 1 and the motor unit 10 for driving the mechanical unit are often installed horizontally for the purpose of saving space. That is, the refrigerant HFC-1
34a and a structure immersed in a mixed oil of refrigerating machine oil. Therefore, when HFC-134a having poor electrical insulation is used as it is in this compressor, ester-based refrigerating machine oil and refrigerant HFC-134a are separated into two layers. That is, since the oil has a low specific gravity, the oil forms the oil layer 12 on the upper side, and the refrigerant forms the refrigerant layer 13 on the lower side. Since the refrigerant HFC-134a contains a large number of hydrogen atoms, it is inherently easy to conduct electricity, and thus, although slightly, electricity is passed from the motor unit 10 to the closed casing 11 through the coolant layer 13. For this reason, there is a possibility that a risk of electric leakage or electric shock may occur.

When the two-layer separation state is eliminated by some means or method, that is, when the liquid refrigerant layer 13 is eliminated, but the electrical insulation of the refrigerating machine oil itself is low, the closed casing 11 is passed through the oil layer 12. Electricity may flow through

Further, the refrigerant HFC134a
The same is true when are mixed.

Accordingly, an object of the present invention is to prevent the occurrence of electric leakage due to the electrical insulation of refrigeration oil. Further, the occurrence of electric leakage is prevented by eliminating the two-layer separation.

[0014]

In order to solve the above-mentioned problems, a horizontal hermetic compressor according to the present invention has a mechanical section and a motor section for driving the mechanical section housed and arranged in a horizontal direction in a closed casing. The closed casing is filled with an HFC-based refrigerant and an ester-based refrigerating machine oil having a volume resistance value of 10 ¹³ Ωcm or more.

Since the volume resistivity of the ester refrigerating machine oil having mutual solubility with the HFC-based refrigerant is 10 ¹³ Ωcm or more, electricity is supplied from the motor unit to the refrigerating machine oil or a mixed liquid of the refrigerating machine oil and the refrigerant through the closed casing. No longer flows to Further, the ester-based refrigerating machine oil having a high volume resistivity has a low hygroscopic property, so that an undesired reaction with the insulating coating of the motor portion and other components is less likely to occur.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A compressor according to one embodiment of the present invention is described below in which a refrigerant is HFC-134a, and a refrigerating machine oil is an ester type refrigerating machine oil having a high critical solution temperature and a volume resistivity of 10 ¹³ Ωcm or more. 1, the same components as those in the conventional example will be denoted by the same reference numerals and description thereof will be omitted.

An embodiment of the present invention will be described with reference to FIG. 14 is a heater installed in the hermetic compressor, and 15 is a control device for energizing the heater 14.

Reference numeral 16 denotes an insulation resistance sensor mounted below the oil supply pipe 8 of the compressor.

Reference numeral 12 denotes a layer of an ester refrigerating machine oil having a volume resistance of 10 ¹³ Ωcm or more, which is separated from the layer 17 of HFC-134a by two layers.

The operation of the hermetic compressor constructed as described above will be described. The shaft 2 is a motor unit 1
By rotating the piston 5 with a rotational force of 0, the piston 5 is moved to compress the refrigerant in the compression chamber 7 formed by the sub-bearings 3, the bearings 4, and the cylinder 6. The temperature of the hermetic compressor increases due to the compression heat and the heat generated by the motor unit 10 at this time. On the other hand, the compressed refrigerant is cooled by the refrigeration system and returns to the compressor again. At this time, the refrigerant HFC-134a and the ester-based refrigerating machine oil are supplied to the machine unit through the oil supply device 8 for lubrication.

When the compressor is heated to a high temperature due to the heat generated during the compression of the refrigerant and the heat generated by the motor unit 10 due to the above operation, the ester-based refrigerating machine oil and the refrigerant HFC-13 are discharged.
4a gradually begins to dissolve, and finally the ester-based refrigerating machine oil and the refrigerant HFC-134a dissolve and the two-layer separation is eliminated. However, when the temperature and pressure inside the compressor decrease when the compressor stops, the refrigerant layer 17 is gradually deposited.

Next, the case where the refrigerant HFC-134a is dissolved in the refrigerating machine oil will be described. The volume resistance value, which is one of the indices indicating the insulating properties, is shown for each substance.

HFC 134a 10 ⁹ Ωcm glycol-based refrigerating machine oil 10 ¹⁰ Ωcm CFC-12 10 ¹⁵ Ωcm Conventional refrigerating machine oil 10 ¹⁴ Ωcm Ester-based refrigerating machine oil 10 ¹³ Ωcm (measured by our company) The larger the value, the higher the insulation. When a large amount of HFC-134a is dissolved in the refrigerating machine oil, the electrical insulation property is rapidly lowered.

According to the present invention, the insulation resistance sensor 16 eliminates the two-layer separation between the refrigerant oil and the refrigerant HFC-134a by utilizing the fact that the insulation resistance changes depending on the amount of the refrigerant dissolved in the refrigerant oil. Refrigerant HFC- in refrigerant oil
The purpose is to reduce the amount of 134a dissolved. That is,
When the motor of the hermetic compressor is stopped, the insulation resistance between the insulation resistance sensor 16 and the hermetic compressor is measured by the insulation resistance sensor 16, and when the insulation resistance falls below a predetermined value, the heater is turned on. Heater 1 by controller 15
4 is energized to heat the refrigerator oil.

That is, when the insulation resistance of the hermetic compressor is reduced to a predetermined value or less by the heater 14 and the control device 15 for energization, the hermetic compressor is heated to heat the refrigerating machine oil and the refrigerant HFC-134a. By raising the temperature, the refrigerant oil and refrigerant HFC-134a are not separated into two layers, eliminating the lubrication of the refrigerant at the time of starting the compressor, and the amount of refrigerant HFC-134a dissolved in the refrigerant oil is reduced and the oil level is reduced. By lowering, the electric insulation is improved, and no current flows in the casing, so that there is no danger of electric leakage or electric shock.

The power consumption can be reduced by turning the heater 14 on and off by the insulation resistance sensor 16.

As described above, according to this embodiment, the amount of the refrigerant HFC-134a dissolved in the refrigerating machine oil is reduced,
The electrical insulation is improved, and the refrigerating machine oil itself uses an ester oil having a large volume resistance value, so that it is possible to more effectively prevent electric leakage and electric shock.

In the above embodiment, HFC-134a has been described as an example of the HFC-based refrigerant. However, a fluorocarbon compound containing at least one hydrogen may be used.

[0029]

According to the horizontal hermetic compressor of the present invention and a refrigeration system including the horizontal hermetic compressor, a mechanical section and a motor section for driving the mechanical section are housed and arranged in a horizontal direction in a closed casing. Since the HFC-based refrigerant and the ester-based refrigerating machine oil having a volume resistance value of 10 ¹³ Ωcm or more are sealed in the closed casing, the high electrical insulation of the ester oil itself effectively prevents electric leakage and electric shock. The windings of the motor section and the insulating film may be those conventionally used without special consideration.

[Brief description of the drawings]

FIG. 1 is a sectional view of a horizontal hermetic compressor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Machine part 10 Motor part 12 Ester refrigerating machine oil 14 Heater 15 Control device for energization 16 Insulation resistance sensor 17 HFC-type refrigerant (HFC-134a)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F04B 49/10 331 F04B 49/10 331Z F25B 1/00 395 F25B 1/00 395Z // C10N 40:30

Claims (3)

[Claims] An HF is provided, wherein a mechanical unit and a motor unit for driving the mechanical unit are housed and arranged in a closed casing in a horizontal direction.
A refrigerant whose main component is a C-based refrigerant and whose volume resistance value is 10 ¹³ Ωc
A horizontal hermetic compressor in which an ester refrigeration oil of at least m is enclosed. 2. The closed casing is provided with a heater for heating the closed casing.
A horizontal hermetic compressor as described. 3. A refrigeration apparatus comprising the horizontal hermetic compressor according to claim 1.