JPH05321837A - Refrigerant compressor - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of a shaft and a bearing and extend the life of a refrigerant compressor by forming the shaft with cast iron, and forming the bearing with powder Al alloy. CONSTITUTION:A sealed container 1 incorporates a motor mechanism, a shaft 3 transmitting the driving force generated by the motor mechanism to a compressing mechanism, and a bearing 4 supporting the shaft 3. The compressing mechanism has a cylinder 7 and a moving member compressing at least one refrigerant selected between HFC and HCF, and a refrigerating machine oil 8 compatible with this refrigerant is stored in the sealed container 1. The shaft 3 is made of cast iron, and the bearing 4 is made of powder Al alloy. The abrasion resistance of the shaft 3 and the bearing 4 is stably maintained over a long period, and a refrigerant compressor excellent in durability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant compressor using at least one refrigerant selected from HFC series and HCFC series, and more particularly to a refrigerant compressor having an improved sliding member.

[0002]

2. Description of the Related Art Refrigerant compressors are often used in indoor or in-vehicle air conditioners, refrigerators, etc. to send out cold air or hot air, and those which are durable under various usage conditions are required. .. This refrigerant compressor is classified into a hermetic refrigerant compressor for a home air conditioner and a semi-hermetic refrigerant compressor for a car air conditioner.

As an example, the structure of a large reciprocating type hermetic refrigerant compressor used in cold chain equipment and commercial refrigerators will be described with reference to FIG. In FIG. 1, a drive motor 2 is housed in an airtight container 1, and a shaft 3 rotated by this motor is supported by a bearing 4. The upper end portion of the shaft 3 is a crank portion (eccentric portion)
The large end 6 of the piston 5 is attached to this crank part.
And the piston 5 reciprocates in the cylinder 7 by the rotation of the shaft 3. The refrigerant gas is sucked from a suction port (not shown) in accordance with the reciprocating motion of the piston 5 accompanying the rotation of the shaft 3, is compressed, and is discharged (not shown).
Is discharged from. Refrigerating machine oil 8 is contained in the closed container 1 in order to facilitate the operation of the sliding portion of the compression mechanism. This refrigerating machine oil 8 is sucked up by the rotation of the shaft 3 along a pump 9 provided at the lower end of the shaft 3,
Lubricate the sliding parts.

The wear generated in the refrigerant compressor having the above-mentioned structure is caused by two causes centering on the piston 5 and the shaft 3. The first reason is that the piston 5, which reciprocates with the rotation of the shaft 3, repeatedly moves in and out with respect to the cylinder 7 at a certain angle, so that a sliding portion between the upper and lower ends of the piston 5 and the inner surface of the cylinder 7 is caused. Extreme pressure (large load) is generated at. Further, in the reciprocal sliding of the piston 5, two stop points at which the sliding speed becomes 0 occur. This is because these two factors cause plastic deformation of the surfaces of the sliding parts and breakage of the lubricating oil film, and the sliding parts are likely to come into metal contact with each other. Therefore, both the piston 5 and the cylinder 7 are easily worn.

The second cause is that the shaft 3 is replaced by the piston 5
This is because the pressure in the cylinder 7 is received via the bearing and the bearing 4 is pressed into a slightly curved shape to rotate at a high speed, so that the lubricating oil film is ruptured and metal contact easily occurs.
Therefore, both the outer surface of the shaft 3 and the inner surface of the bearing 4 are easily worn.

On the other hand, the bearing 4 of the large reciprocating type hermetic refrigerant compressor as shown in FIG. 1 is being made of an aluminum alloy because of the need to reduce the production cost. Above all AD
Aluminum die castings such as C12 are most often used because they have high productivity and are suitable for mass production. However, compared with iron-based materials that have been conventionally used, aluminum alloy materials have a problem that they are easily hard to be plastically deformed due to their low hardness and are inferior in sliding characteristics, and thus are easily worn. Further, since aluminum alloy materials are not suitable for surface treatment such as alumite treatment or chemical conversion treatment, there is a problem that improvement in wear resistance cannot be expected.

Conventionally, dichlorodifluoromethane (hereinafter abbreviated as CFC12) has been mainly used as a refrigerant in such a large reciprocating type hermetic refrigerant compressor, and as a refrigerating machine oil to be enclosed, CFC12 is used. A naphthenic or paraffinic mineral oil that is compatible with is used.

When CFC12 is used as the refrigerant, chlorine (Cl) atoms in CFC12 react with iron (Fe) atoms of the metal base material to form a lubricating film made of iron chloride. This iron chloride lubricating film is self-lubricating and has excellent wear resistance, preventing metal contact even under extreme pressure (large load) load or when sliding speed becomes 0, and is effective in preventing wear. To work. In addition, since the conventional refrigerant CFC12 and conventional refrigeration oil are both non-polar,
Low hygroscopicity. Therefore, the iron chloride layer formed on the iron-based metal substrate could exist as a stable film without causing hydrolysis.

By the way, recently, it has been clarified that the release of the above-mentioned CFC type refrigerant and the like leads to the destruction of the ozone layer and seriously affects the human body and biological systems. For this reason, the use of CFC12, which has a high ozone depletion potential (ODP), has been gradually reduced, and it has been decided internationally that it will not be used in the future.

In order to cope with such a situation, chlorodifluoromethane (hereinafter referred to as HCFC2) is used as an alternative refrigerant for CFC12.
It is abbreviated as 2. ) And other HCFC-based refrigerants, 1,1,1,2-tetrafluoroethane (hereinafter abbreviated as HFC134a), 1,
HFC-based refrigerants such as 1-difluoroethane (hereinafter abbreviated as HFC152a) have been developed. HFC134a and HFC152a
Does not contain a chlorine (Cl) atom in the molecule, and has an ozone depletion potential (ODP) of 0. Furthermore, since the thermal characteristics of the refrigerant are close to those of CFC12, there is no need to significantly change the design of the compression mechanism. Therefore, CF
Very useful as an alternative refrigerant for C12. Also, HCFC2
2 has an extremely low ozone depletion potential (ODP), so CFC1
It is useful as an alternative refrigerant for 2.

Along with the development of HFC134a and HFC152a, it is desired to develop a compressor material suitable for these alternative refrigerants. On the other hand, during operation of the refrigerant compressor, it is necessary to prevent the refrigerating machine oil from remaining in the refrigeration cycle, reliably return the refrigerating machine oil to the compression mechanism section of the refrigerant compressor, and maintain lubrication and cooling of the compression mechanism section. .. Therefore, HF is used as the refrigerant for the refrigerant compressor.
When using C134a or HFC152a, it is necessary for the properties of the refrigerating machine oil to be compatible with the refrigerant. But HF
C134a and HFC152a are hardly soluble in conventional naphthenic refrigerating machine oil, mineral oil. Therefore, attempts have been made to use polyether oils, polyester oils, fluorine oils and the like that are compatible with HFC134a and HFC152a.

[0012]

[Problems to be Solved by the Invention] However, the above-mentioned HFC1
When HFC refrigerants such as 34a and HFC152a and polyether oils and polyester oils that are compatible with this HFC refrigerant are used in the refrigerant compressor, they are used as sliding members of the compression mechanism. The wear resistance of cast iron, carbon steel, alloy steel, sintered alloys, stainless steel, etc. is deteriorated, which causes a problem that the refrigerant compressor cannot be operated stably for a long period of time. Especially the shaft is made of cast iron,
If the bearing is made of aluminum die-cast, wear resistance is likely to be significantly reduced in the sliding parts of each other, and plastic deformation of the bearing is likely to occur, so the refrigerant compressor operates stably for a long time. The problem is that you cannot do it.

The following can be considered as the cause of this. First, when CFC12 is used as the refrigerant, the iron chloride film formed on the metal substrate has self-lubricating property and excellent wear resistance. On the other hand, when using HFC134a or HFC152a,
Since there is no chlorine (Cl) atom, the lubricating film made of the iron chloride film is not formed.

Secondly, the naphthene type refrigerating machine oil contains a cyclic compound and has a high oil film forming ability. On the other hand, HFC134
Refrigerating machine oil that is compatible with a or HFC152a is a chain compound that does not contain a cyclic compound, and thus has a low oil film forming ability and cannot hold an oil film under severe sliding conditions. Therefore, additives such as extreme pressure additives are added to the polyether oil and polyester oil.

Thirdly, aluminum die castings such as ADC 12 are not so good in wear resistance themselves and have low hardness, so they are prone to plastic deformation.

Therefore, especially when HFC134a or HFC152a is used as a refrigerant and a refrigerating machine oil having compatibility with these refrigerants, for example, a polyalkylene glycol oil or a polyester oil is used, the sliding member is in operation. When extreme pressure (large load) is applied to the
Even when it becomes 0, it is possible to prevent the plastic deformation of the bearing sliding surface and the wear of the shaft and the bearing due to the occurrence of the breakage of the lubricating oil film, and to make the refrigerant compressor usable for a long period of time.
It is an issue that needs to be resolved immediately.

The present invention has been made to solve the above problems, and when using HFC-based and HCFC-based refrigerants, it is possible to improve the wear resistance of shafts and bearings and to extend the life of the refrigerant compression. The purpose is to provide a machine.

[0018]

The refrigerant compressor of the present invention comprises:
A motor mechanism, a shaft for transmitting the driving force generated by the motor mechanism to the compression mechanism, and a bearing for supporting the shaft are built in the airtight container, and the compression mechanism slides in contact with the cylinder and the HFC system and In a refrigerant compressor having a movable member for compressing at least one refrigerant selected from HCFC system and containing refrigerating machine oil compatible with the refrigerant, the shaft is made of cast iron, and the bearing is powder Al alloy. It is characterized by consisting of.

As the cast iron used in the shaft according to the present invention, the materials used in ordinary hermetic compressors can be used. For example, FC250 (JIS standard, G
5501).

Powder Al used in the bearing according to the present invention
As the alloy, various combinations of alloys are possible,
Most preferable is a powdered Al alloy containing 25 to 30% by weight of Si particles having a diameter of 3 to 6 μm. Si particle diameter is 3 ~ 6
When the content is in the range of 25 to 30% by weight, the Si particles do not act as a starting point of wear, and the cast iron, which is the mating sliding member, does not wear. Further, the machinability does not significantly decrease.

The HFC type refrigerant according to the present invention is preferably a compound composed of carbon, hydrogen and fluorine, and the thermal characteristic of the refrigerant is close to that of CFC12. Preferred compounds are HFC134a and HFC152a. The HCFC-based refrigerant preferably has an extremely low ozone depletion potential (ODP), such as HCFC22. These HFC-based refrigerants and HCFC-based refrigerants can be used alone or in a mixture.

The refrigerating machine oils compatible with the above HFC refrigerants include polyether oils, polyester oils and fluorine oils, and the refrigerating machine oils compatible with the HCFC refrigerants include naphthene-based or paraffin-based oils. Examples include mineral oils.

As a combination of a refrigerant and a refrigerating machine oil that are less likely to cause ozone layer depletion, a refrigerant such as HFC134a or HFC152a and a refrigerating machine oil such as a polyether type oil, a polyester type oil or a fluorine type oil are preferable.

[0024]

As described above, the sliding member using cast iron for the shaft and powdered Al alloy for the bearing has the following effects on the sliding surface. First, extreme pressure (large load) on the sliding surface
When loaded, Si with high hardness existing on the surface of the powdered Al alloy
Since the particles slide while protruding from the Al base material, wear resistance is improved. Secondly, even under the condition where the lubricating oil film breaks and metal contact occurs, the Si particles project on the surface of the powdered Al alloy to form an oil reservoir, which improves the lubricating oil retaining property. Third, since the powder Al alloy is used for the bearing, the material strength and hardness are increased, and plastic deformation of the bearing is avoided.

As described above, the sliding of the shaft and the bearing in a refrigerant compressor using an HFC type refrigerant and a refrigerating machine oil compatible with the HFC type refrigerant, for example, polyether type oil, fluorine type oil, polyester type oil, etc. The wear resistance of the portion is improved, and the plastic deformation of the bearing is prevented. Therefore, the life of the refrigerant compressor can be extended. Further, since the powder Al alloy according to the present invention is easy to perform near net shape molding with a small volume shrinkage during molding, the productivity of the bearing is improved and the production cost is reduced.

[0026]

EXAMPLES The present invention will be described in detail below based on examples. Example 1 An example in which the sliding member according to the present invention is applied to the shaft 3 and the bearing 4 of the hermetic refrigerant compressor shown in FIG. 1 will be described. Since the structure of the hermetic refrigerant compressor of this embodiment is the same as the structure of the conventional hermetic refrigerant compressor shown in FIG. 1, it will be described with reference to FIG.

The shaft 3 in the first embodiment is made of cast iron (F
(C250) A base material was cut into a predetermined shape and manufactured.

The bearing 4 was manufactured by the following method. First,
Powder A containing 26% by weight of Si particles having a diameter of 3 to 4 μm
A predetermined amount of 1 was filled in a bearing mold by a vibration method or the like.
After that, molding under pressure molding conditions of 400 ℃, 200 kg / cm ² ,
The powder Al alloy bearing 4 was obtained by performing a cutting process for increasing accuracy.

The wear resistance of the obtained shaft and bearing was evaluated using an apparatus as shown in FIG. This device
In a refrigerant HFC134a atmosphere, a ring 10 made of the same material as the bearing 4 is made to face a disk 11 made of the same material (FC250) as the shaft 3, and pressure is applied from the rear of the ring 10 so that the disk 11 has a constant radius. The driving motor 12 is used to make a turning motion. In this test,
Lubricating the sliding surfaces of the ring 10 and the disk 11 with a polyester refrigerating machine oil compatible with HFC134a, a surface pressure of 30 kgf / cm ² and a sliding speed of 0.75 m / s were tested for 3 hours. The wear amount (weight) of the ring 10 and the disk 11 was examined. The measurement result is shown in FIG. Note that FIG.
2 indicates that the smaller the amount of wear of the ring 10, the higher the wear resistance of the ring material, and the smaller the amount of wear of the disk 11, the smaller the attack of the ring material on the disk material (counterpart material). Therefore, the smaller the wear amounts of the ring 10 and the disk 11, the better the sliding member. According to FIG. 3, the sliding characteristics of the powdered Al alloy material of Example 1 were superior to those of the cast Al of Comparative Example 4.

Further, a bearing 4 was produced using the powdered Al alloy material of Example 1, and a shaft 3 was produced using FC250,
Assemble the refrigerant compressor shown in Fig. 1 and use HFC134a as the refrigerant.
And a polyester-based refrigerating machine oil compatible with HFC134a was used as a refrigerating machine oil, and a real machine test was conducted.
Bearing 4 and shaft 3 even after running for a long time of 0 hours
No wear was observed between the two, indicating good wear resistance.

Example 2 A shaft 3 and a bearing 4 having the same shapes as in Example 1 were used, except that powder Al containing 25 wt% of Si particles having a diameter of 4 to 5 μm was used as the material of the bearing 4. It was produced by the method. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG. The sliding properties of Example 2 were superior to those of Comparative Examples 1 to 4.

Example 3 A shaft 3 and a bearing 4 having the same shape as in Example 1 are the same as those in Example 1 except that powder Al containing 30% by weight of Si particles having a diameter of 5 to 6 μm is used as the material of the bearing 4. It was produced by the method. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG. Compared with the sliding characteristics of Comparative Examples 1 to 4, the sliding characteristics of Example 3 were excellent.

Comparative Example 1 A shaft 3 and a bearing 4 having the same shape as in Example 1 are the same as those in Example 1 except that powder Al containing 17% by weight of Si particles having a diameter of 1 to 2 μm is used as the material of the bearing 4. It was produced by the method. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG.

Comparative Example 2 A shaft 3 and a bearing 4 having the same shape as in Example 1 are the same as those in Example 1 except that powder Al containing 35% by weight of Si particles having a diameter of 1 to 2 μm is used as the material of the bearing 4. It was produced by the method. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG.

Comparative Example 3 A shaft 3 and a bearing 4 having the same shape as in Example 1 were the same as in Example 1 except that powder Al containing 35% by weight of Si particles having a diameter of 3 to 4 μm was used as the material of the bearing 4. It was produced by the method. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG.

Comparative Example 4 A shaft 3 having the same shape as that of Example 1 was manufactured by the same method as that of Example 1. Moreover, as a material, Si with a diameter of 7 to 8 μm is used.
A bearing 4 was produced using cast Al containing 17% by weight of particles. The wear resistance of the obtained shaft and bearing was evaluated using the same device as in Example 1. The measurement result is shown in FIG.

[0037]

The refrigerant compressor of the present invention uses HFC as a refrigerant.
System and at least one refrigerant selected from the HCFC system,
Refrigerating machine oil compatible with these refrigerants as refrigerating machine oil is housed in a closed container, the shaft of the compression mechanism is cast iron, the bearing is 3 to 6 μm, and the Si particles are 25 to 30 μm.
Since it is made of the powdered Al alloy containing wt%, the wear resistance of the shaft and the bearing can be stably maintained for a long period of time, and a refrigerant compressor excellent in durability can be obtained. Also, in the production of bearings, since the powder Al alloy according to the present invention is easy to perform near net shape molding with small volume shrinkage at the time of molding, it is possible to easily and efficiently produce highly accurate bearings.
As a result, the production cost of the refrigerant compressor is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a refrigerant compressor showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of a friction and wear tester.

FIG. 3 is a diagram showing the results of an abrasion resistance test.

[Explanation of symbols]

1 ...... Closed container, 2 ......... Motor, 3 ......... Shaft, 4 ......... Bearing, 5 ...... Piston, 6 ......... Large end, 7 ......... Cylinder, 8 ... Machine oil, 9 ... Pump, 10 ... Ring, 11 ... Disk, 12 ...
...... Device drive motor.

Claims (1)

[Claims] 1. A motor mechanism, a shaft for transmitting a driving force generated by the motor mechanism to a compression mechanism, and a bearing for supporting the shaft are built in a hermetic container, and the compression mechanism includes a cylinder and a cylinder. HFC system and
In a refrigerant compressor having a movable member for compressing at least one refrigerant selected from HCFC system, and containing refrigerating machine oil compatible with the refrigerant, the shaft is made of cast iron, and the bearing is A refrigerant compressor comprising a powdered Al alloy.