JPH10141227A - Compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability and efficiency of a compressor, in a compressor to be used for a refrigerator-freezer, an air conditioner or the like. SOLUTION: An oil supplying passage to sliding parts of a cylinder 14 in which a supply hole 14a is formed on the upper part, and a piston 15 in which one oil groove 15a is formed on the front surface in the slide direction and two oil grooves 15b are formed on parts separated from both end surfaces by 10mm or less is formed, gas nitriding treatment and steam treatment in which the moisture content in NH3 gas is in the range of 3 to 10% are performed to the front surface of the piston 15, a solid solution layer having the whole film thickness in the range of 20 to 30μm or more and containing nitrogen and oxygen is formed, and an oxide film layer is formed on it, and therefore, high durability and high efficiency of a compressor can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor for use in a refrigerator or an air conditioner.

[0002]

2. Description of the Related Art In recent years, due to environmental problems such as destruction of the ozone layer and the like, the production of difluorodichloromethane (hereinafter referred to as CFC-12) containing chlorine in a molecule, which has been conventionally used, and its use in a freezing and refrigeration apparatus have been increasing. As a substitute, refrigerants 1, 1, 1, and 2 tetrafluoroethane (hereinafter, referred to as HFC-134a) containing no chlorine in the molecule are enclosed as a substitute. However, since the refrigerant containing no chlorine in the molecule has poor lubricating performance, abrasion occurs in the sliding portion where the abrasion did not occur in the case of the conventional refrigerant, the sliding loss increased, and the durability of the compressor increased. Causes a decline in sex. Therefore, it is necessary to improve the characteristics of the sliding material of the compressor and review the component configuration and the like.

An example of a conventional compressor will be described with reference to FIG. 1 is a compressor. Reference numeral 2 denotes a shaft, 3 denotes a rotor, and 4 denotes a stator. The rotor 3 and the stator 4 form an electric motor as a pair. 5 is a connecting rod, 6 is a cylinder, 7 is a piston, and 8 is a piston pin. The shaft 2 press-fitted into the rotor 3 rotates along with the bearing 9 by the motor formed by the rotor 3 and the stator 4. At this time, via a connecting rod 5 attached to the eccentric portion of the shaft 2 and a piston pin 8 attached to the other end of the connecting rod 5 and fixed to a piston 7,
The rotation of the shaft 2 is transmitted, and the piston 7 reciprocates in the cylinder 6. And the piston 7 and the cylinder 6
In the space 10 defined by the above, the refrigerant gas is sucked and compressed. After the lubricating oil 12 in the lower part of the compressor is pumped up by the oil supply pipe 13 attached to the lower part of the shaft, the oil is supplied to the shaft 2 by a spiral oil supply groove.
It is further pumped to the upper part of the compressor, and is supplied to each sliding part.

Here, conventionally, the cylinder 7 is made of cast iron (J
IS: FC200). One piston 8
Is made of cast iron (JIS: FC200), and its surface is subjected to a lubricating treatment.

[0005]

The lubricating oil 1 pumped up by an oil supply pipe 13 attached to the lower part of the shaft 2
Numeral 2 is supplied to various sliding parts in the compressor by a spiral oil supply groove, oil supply hole, oil reservoir, oil groove and the like provided on the shaft 2.

Here, the lubrication of the sliding portion between the cylinder 7 and the piston 8 is performed as follows. The lubricating oil 1 which reaches the sliding portion between the shaft 2 and the connecting rod 5 from the oil supply hole formed in the lower part of the shaft 2 by the rotation of the shaft 2
A part of 2 passes through an oiling hole formed in the connecting rod 5,
It reaches the sliding portion between the connecting rod 5 and the piston pin 8.
The lubricating oil 12 discharged from the sliding part between the connecting rod 5 and the piston pin 8 is supplied to the sliding part between the cylinder 7 and the piston 8. However,
Since the sliding portion between the cylinder 7 and the piston 8 is farthest from the oil supply pipe 13 provided at the lower portion of the shaft 2, the supply amount of the lubricating oil 12 is insufficient compared with the other sliding portions. It can be said that the lubrication conditions in this sliding portion are inferior.

[0007] However, even in the above-described configuration, the CFC-
The reason why abnormal wear or seizure did not occur in the sliding portion between the cylinder 7 and the piston 8 in the compressor using the refrigerant 12 as the refrigerant is due to the CFC-1 encapsulated as the refrigerant.
This is because No. 2 itself had high lubrication performance. Further, the lubricite coating layer 8a formed on the surface of the piston 8 and having a thickness of several μm exerts a wear resistance effect.

In the case of a compressor in which refrigerant HFC-134a having poor lubricating performance and containing no chlorine in the molecule is sealed, the sliding condition between the cylinder 7 and the piston 8 is particularly poor in lubricating conditions as compared with other sliding portions. In the portion, the sliding members cause metal contact with each other, and the lubricite coating layer 8a having a thickness of several μm is worn away, exposing the base material. In addition, the side surfaces near the both end surfaces of the piston, where the amount of supplied oil is small and the oil film is liable to be cut off, are particularly likely to be worn and tend to progress. Once sliding occurs between the cast irons as the base materials, adhesive wear occurs, and if this progresses, the possibility of abnormal wear or seizure increases.
Further, in order to achieve energy saving and high efficiency of the refrigerator in recent years, measures such as a variable speed operation of the compressor 1 and a low viscosity of the lubricating oil 12 are being taken. Therefore, lubricating oil 1
It can be said that the lubrication conditions of the sliding material tend to be more severe due to factors such as poor oil film forming property of 2, and difficulty in sufficiently supplying the lubricating oil 12 to each sliding portion. As a result, in the above-described configuration, the amount of wear is increased and not only the sufficient durability of the compressor is not obtained, but also the sliding loss is increased, so that the compression efficiency is deteriorated and the efficiency cannot be improved.
Therefore, it is urgently necessary to newly optimize the sliding material for the refrigerant containing no chlorine.

[0009] In view of the above problems, the present invention provides a refrigerant HFC-1.
It is an object of the present invention to optimize a sliding material and to easily form an oil film for a compressor using 34a, to reduce a sliding loss of the compressor and to improve the durability of the compressor. .

[0010]

In order to solve the above-mentioned problems, a compressor according to the present invention has a through-hole formed in an upper part of a cylinder,
And an oil groove on the piston surface in the sliding direction of the piston 1
Two oil pipes are formed within 10 mm from both end faces of the piston to form an oil supply passage to a sliding portion between the piston and the cylinder connected with the oil groove, and the entire surface of the piston contains water in NH ₃ gas. The gas nitriding treatment and the steam treatment with the amount of 3 to 10% are simultaneously performed to form a solid solution layer containing nitrogen and oxygen having a total film thickness of 20 to 30 μm or more, and an oxide film layer formed thereon. . According to the present invention, the wear of the cylinder and the piston is prevented, and the sliding loss is reduced,
As a result, improvement in durability and high efficiency of the compressor can be realized.

In order to solve the above problems, a compressor according to the present invention has a through hole formed in the upper part of a cylinder, and one oil groove in the piston surface in the sliding direction of the piston and two oil grooves within 10 mm from both end faces of the piston. Forming and forming an oil supply passage to a sliding portion between the cylinder and the piston connected with the oil groove, and performing a salt bath nitriding treatment and a steam treatment on the entire surface of the piston to have a total film thickness of 20 to 30 μm or more. And an oxide film layer formed thereon. ADVANTAGE OF THE INVENTION According to this invention, wear of a cylinder and a piston is prevented and sliding loss is reduced, As a result, improvement of durability and high efficiency of a compressor can be implement | achieved.

In order to solve the above problems, a compressor according to the present invention has a through hole formed in the upper part of a cylinder, and has one oil groove in the piston surface in the sliding direction of the piston and two oil grooves within 10 mm from both end surfaces of the piston. The oil groove is formed to form an oil supply path to a sliding portion between the cylinder and the piston connected with the oil groove, and the entire surface of the piston is subjected to a salt bath nitriding treatment in which a sulfur compound is added. A nitrided layer having a thickness of 30 μm or more and a sulfide film layer formed thereon.
ADVANTAGE OF THE INVENTION According to this invention, wear of a cylinder and a piston is prevented and sliding loss is reduced, As a result, improvement of durability and high efficiency of a compressor can be implement | achieved.

[0013]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a through hole is formed in the upper part of a cylinder, and one oil groove is formed on the piston surface in the sliding direction of the piston within 10 mm from both end faces of the piston. A gas whose NH ₃ gas has a water content of 3 to 10% on the entire surface of the piston while forming two oil passages to a sliding portion with a cylinder piston connected to the oil groove. A nitriding treatment and a steam treatment are simultaneously performed to form a solid solution layer containing nitrogen and oxygen having a total thickness of 20 to 30 μm or more, and an oxide film layer formed thereon. Thereby, wear of the cylinder and the piston is prevented, and sliding loss is reduced. As a result, improvement in durability and high efficiency of the compressor can be realized.

According to a second aspect of the present invention, a through hole is formed in the upper part of the cylinder, and one oil groove is formed on the piston surface in the sliding direction of the piston.
In addition to forming an oil supply passage to the sliding part between the piston and the cylinder having the oil grooves connected to each other within 2 mm, the entire surface of the piston is subjected to a salt bath nitriding treatment and a steam treatment to provide a total film thickness. Has a nitriding layer having a thickness of 20 to 30 μm or more and a thrust receiver having an oxide film layer formed thereon. Thereby, wear of the cylinder and the piston is prevented, and sliding loss is reduced. As a result, improvement in durability and high efficiency of the compressor can be realized.

According to a third aspect of the present invention, a through hole is formed in the upper part of the cylinder, and one oil groove is formed on the piston surface in the sliding direction of the piston.
In addition to forming an oil supply passage to the sliding portion between the cylinder and the piston having the two oil grooves formed therein within 2 mm and connecting the oil groove, the entire surface of the piston is subjected to a salt bath nitriding treatment in which a sulfur compound is added. It has a nitriding layer having a film thickness of 20 to 30 μm or more, and a thrust receiver having a sulfide coating layer formed thereon. Thereby, wear of the cylinder and the piston is prevented, and sliding loss is reduced. As a result, improvement in durability and high efficiency of the compressor can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The overall configuration of the compressor is the same as that of the conventional example, and a detailed description is omitted.

(Embodiment 1) FIG. 1 is an enlarged sectional view of the vicinity of a sliding portion between a cylinder 14 and a piston 15 according to this embodiment. Note that HFC-134a is used as the compressed gas.

As shown in FIG. 1, after the cylinder 14 is machined from cast iron (JIS: FC200), an oil supply hole 14a is formed in the upper part of the cylinder to supply oil to a sliding portion between the cylinder 14 and the piston 15. In the processing location of the oil supply hole 14a, the length A from the oil supply hole 14a to the valve plate 16 is larger than the maximum stroke length B of the piston 15. On the other hand, the piston 15 is made of cast iron (JIS: FC20).
After processing in step 0), one oil groove 15a having an obtuse angle of 90 ° or more is formed on the surface thereof in parallel with the sliding direction of the piston 15. The oil groove 15a is formed at a position where the lubricating oil 12 can be directly supplied to the oil groove 15a formed on the piston surface from the oil supply hole 14a formed in the upper part of the cylinder 14. Further, two oil grooves 15b having the same shape and having a triangular vertex at a position 5 mm from both end surfaces of the piston 15 are formed. In addition, the oil groove 15a is formed up to the oil groove 15b formed on both end surfaces of the piston 15,
Connect. This is because the oil groove 15a also has a role of allowing the lubricating oil 12 to reach the oil groove 15b near both end surfaces of the piston 15.

FIG. 2 is a partial view of the piston 15 according to the first embodiment as viewed from the side. The piston 15 is formed by processing the base material 15c as cast iron (JIS: FC200).
Further, after the oil grooves 15a and 15b are formed, a gas nitriding method and a steam processing method in which the water content in NH ₃ is 5% and the processing temperature is 500 to 520 ° C. are performed, and the total film thickness is 20 to 30.
A solid solution layer 15d containing nitrogen and oxygen of at least μm and an oxide film layer 15e formed thereon. The outermost oxide film layer 15e is porous and is mainly made of pure magnetite.

The lubricating oil pumped up from the oil supply pipe by a spiral oil supply groove or the like formed on the shaft is discharged from the sliding portion between the bearing and the thrust washer, and is returned to the upper portion of the cylinder by the time it returns to the original compressor lower portion. A part of the lubricating oil is collected. The collected lubricating oil is supplied to an oil groove provided in the upper part of the piston through an oil supply hole provided in the upper part of the cylinder. The three oil grooves formed on the surface of the piston can supply lubricating oil to the sliding portion between the cylinder and the piston, especially to the side surfaces near the both end surfaces of the piston where the occurrence and progress of wear are remarkable. Therefore, the amount of lubricating oil supplied to the sliding portion between the cylinder and the piston is increased as compared with the related art, and the lubricating conditions can be improved. Furthermore, the iron oxide film layer formed on the piston surface is porous, and when lubricating oil is supplied, the lubricating oil penetrates into the oxide film layer, making it easier to form an oil film on the sliding surface.

In the case where a sufficient oil film is not formed on the sliding surface between the cylinder and the piston due to an extremely small amount of supplied oil, for example, immediately after the start of the compressor, a lubricated layer is formed on the piston surface. With only the film thickness, the thickness is very small, several μm. Therefore, once abrasion due to metal contact progresses, there is a high possibility that the lubricated layer is instantaneously lost. Further, by forming only the gas nitriding layer on the surface of the piston, the hardness of the material of the piston is HV100.
Although the wear resistance of the piston itself is improved due to the increase of 0 to 1200, on the other hand, the aggressiveness to the cylinder increases, and there is a possibility that abnormal wear may be caused on the sliding surface of the cylinder. Therefore, if the oil film as described above is hardly formed only by improving the wear resistance of the piston itself, it is not possible to add sufficient wear resistance to the sliding portion between the cylinder and the piston. However, the oxide film layer formed on the surface of the piston in the present invention has slip characteristics, and the slip characteristics can reduce the friction coefficient of the sliding portion. A metal,
Since it has excellent non-adhesiveness to the alloy, and the hardness of the piston itself is HV1000 to 1200, it is possible to prevent adhesive wear due to metal contact in the sliding portion between the cylinder and the piston. . Therefore,
Lubrication holes and oil grooves provided for forcibly lubricating the sliding parts of the cylinder and piston, and double adhesion wear due to gas nitriding and steam treatment with slip characteristics and non-adhesion applied to the piston surface By the synergistic effect of the preventive measures and the oil film forming property improving measures, abnormal wear and seizure of the sliding portion between the cylinder and the piston can be prevented and sliding loss can be reduced even under HFC-134a having poor lubricating performance.

As described above, in the present embodiment, HFC-134a is used as the gas to be compressed, a through hole is formed in the upper part of the cylinder of the compressor, and an oil groove is formed on the piston surface in the sliding direction of the piston. Book, 10 from both ends of piston
The oil supply passage to the sliding portion between the cylinder and the piston, which is formed within 2 mm and connected to the oil groove, is formed, and the water content of NH ₃ gas is 3 to 10 on the entire surface of the piston.
% Gas nitriding and water vapor treatment to give a total film thickness of 2%.
By forming a solid solution layer containing nitrogen and oxygen of 0 to 30 μm or more and an oxide film layer thereon, wear of the cylinder and piston is prevented, and sliding loss is reduced. Durability and compression efficiency can be improved.

In this embodiment, the oil groove on the piston surface has a triangular shape having a groove angle of 90 ° or more.
The corners should be chamfered into rounded triangles,
Although the number of steps is increased, it is desirable from the viewpoint of the oil film forming property of the sliding portion between the cylinder and the piston. In addition, even if the shape of the oil groove is a trapezoidal shape, the same effect as in the case of a triangular shape can be obtained.

In the present embodiment, the oil grooves having the purpose of connecting the oil grooves formed on both end surfaces of the piston are parallel to the sliding direction, but are angled with respect to the stroke direction. The same effect can be obtained as long as there is at least one point where lubricating oil can be directly supplied to the oil groove formed in the piston from the oil supply hole formed in the cylinder during the reciprocation of the piston. Is obtained. In addition, in the present embodiment, the position of the oil groove provided on the side surface near both end surfaces of the piston is 5 m from both end surfaces.
m is a triangular vertex.
The same effect can be obtained if the distance is within mm.

The cylinder has one oil supply hole. However, if the length A of the oil supply hole from the oil supply hole to the valve plate is larger than the maximum stroke length B of the piston, A plurality may be provided.

In the gas nitriding treatment and the steam treatment in the present embodiment, the water content in the NH ₃ atmosphere is 5%.
However, even when the thickness is 3 to 10%, the total film thickness is 20 to 30 μm.
Thus, the same slip characteristics and non-adhesiveness improving effect can be obtained. However, if the water content is less than 3%,
When the content is 10% or more, the thickness of the solid solution layer becomes small in both cases, and sufficient sliding properties and non-adhesion properties cannot be obtained, resulting in poor wear resistance.

Further, after the oil groove processing of the piston is performed, the entire surface of the piston is subjected to gas nitriding treatment and steam treatment. However, even if the oil groove processing is performed in a later step, the wear resistance is not affected. The effect is obtained.

Although HFC-134a is used as the gas to be compressed in the present embodiment, R-407C and 4-410A which do not contain chlorine in the molecule like the refrigerant.
The same effect can be obtained even if a hydrocarbon gas or the like is used.

(Embodiment 2) FIG. 3 is an enlarged sectional view of the vicinity of a sliding portion between a cylinder 14 and a piston 17 according to the present embodiment.

The gas to be compressed is HFC-134a
Is used. As shown in FIG. 3, after the cylinder 14 is machined with cast iron (JIS: FC200), an oil supply hole 14 a is formed in an upper portion of the cylinder to supply oil to a sliding portion between the cylinder 14 and the piston 17. In the processing location of the oil supply hole 14a, the length A from the oil supply hole 14a to the valve plate 16 is larger than the maximum stroke length B of the piston 15. On the other hand, the piston 17 is made of cast iron (JIS: FC20).
After processing in step 0), one oil groove 17a having an obtuse angle of 90 ° or more is formed on the surface of the oil groove 17a in parallel with the sliding direction of the piston 17. The oil groove 17a is formed at a position where the lubricating oil 12 can be directly supplied to the oil groove 17a formed on the piston surface from the oil supply hole 14a formed in the upper part of the cylinder 14. Further, two oil grooves 17b having the same shape and having a triangular vertex at a position 5 mm from both end surfaces of the piston 17 are formed. The oil groove 17a is formed up to oil grooves 17b formed on both end faces of the piston 17,
Connect. The oil groove 17a is located near both end faces 17 of the piston 17.
This is because it also plays a role of causing the lubricating oil 12 to reach b.

FIG. 4 is a partial view of the piston 17 according to the second embodiment as viewed from the side. The piston 17 is formed by processing the base material 17c as cast iron (JIS: FC200),
Further, after forming the oil grooves 17a and 17b, the processing temperature 50
A salt bath nitriding treatment and a steam treatment were performed at 0 to 600 ° C. for 1.5 to 2 hours, and the total film thickness was 20 to 30 μm.
The nitriding layer 17d composed of the above and the oxide film layer 1 thereon
7e. The outermost oxide film layer 17e is porous and is mainly made of pure magnetite.

The lubricating oil pumped up from the oil supply pipe by a spiral oil supply groove or the like formed on the shaft is discharged from the sliding portion between the bearing and the thrust washer, and is returned to the upper part of the cylinder by the time it returns to the original compressor lower part. A part of the lubricating oil is collected. The collected lubricating oil is supplied to an oil groove provided in the upper part of the piston through an oil supply hole provided in the upper part of the cylinder. The three oil grooves formed on the surface of the piston can supply lubricating oil to the sliding portion between the cylinder and the piston, especially to the side surfaces near the both end surfaces of the piston where the occurrence and progress of wear are remarkable. Therefore, the amount of lubricating oil supplied to the sliding portion between the cylinder and the piston is increased as compared with the related art, and the lubricating conditions can be improved. Furthermore, the iron oxide film layer formed on the piston surface is porous, and when lubricating oil is supplied, the lubricating oil penetrates into the oxide film layer, making it easier to form an oil film on the sliding surface.

For example, when a sufficient oil film is not formed on the sliding surface between the cylinder and the piston due to an extremely small amount of supplied oil, for example, immediately after the start of the compressor, the film is formed only by forming the lubricated layer on the piston surface. Since the thickness is as thin as several μm, once the abrasion due to metal contact progresses, there is a high possibility that the lubricated layer disappears instantaneously.
Further, by forming only the salt bath nitriding layer on the surface of the piston, the hardness of the piston material is HV700 to 800.
Therefore, the wear resistance of the piston itself is improved, but on the other hand, the aggressiveness against the cylinder is increased, and there is a possibility that abnormal wear may be caused on the sliding surface of the cylinder.
Therefore, if the oil film as described above is hardly formed only by improving the wear resistance of the piston itself, it is not possible to add sufficient wear resistance to the sliding portion between the cylinder and the piston. However, the oxide film layer formed on the surface of the piston in the present invention has a slip characteristic,
It is possible to reduce the friction coefficient of the sliding part by this sliding property, the oxide film layer has excellent non-adhesion property to the metal or alloy as the mating material, and the hardness of the piston itself is HV700. Since it is ８００800, adhesive wear due to metal contact in the sliding portion between the cylinder and the piston can be prevented beforehand.

Therefore, an oil supply hole and an oil groove provided for forcibly supplying oil to a sliding portion of the cylinder and the piston,
Double adhesion abrasion prevention measures by salt bath nitridation and steam treatment with slip characteristics and non-adhesion applied to the piston surface,
Also, due to the synergistic effect of the oil film forming property improving measure, abnormal wear and seizure of the sliding portion between the cylinder and the piston can be prevented and the sliding loss can be reduced even under HFC-134a having poor lubrication performance.

As described above, in the present embodiment, HFC-134a is used as the gas to be compressed, a through hole is formed in the upper part of the cylinder of the compressor, and an oil groove is formed on the piston surface in the sliding direction of the piston. Book, 10 from both ends of piston
The oil supply path to the sliding portion between the cylinder and the piston in which the oil groove is frozen by forming two oil grooves within mm is formed, and a processing temperature of 500 to 600 ° C. and a processing time of 1.5 to By performing a salt bath nitriding treatment and steam treatment for 2 hours to form a solid solution layer containing nitrogen and oxygen having a total film thickness of 20 to 30 μm or more and an oxide film layer thereon, the cylinder and the piston are formed. Wear can be prevented and sliding loss can be reduced, so that the durability and compression efficiency of the compressor can be improved.

The hardness of the nitriding layer formed by the salt bath nitriding method in this embodiment is about 1/2 to 2/3 of the hardness of the solid solution layer formed by the gas nitriding method. The sliding properties of the oxide film layer on the outer periphery and the non-adhesiveness to the mating metal or alloy are almost the same as those of the gas nitriding method. Here, in the case of the salt bath nitriding treatment method, the time required for the treatment is 1.5 to 1 hour,
Even if the processing time required for the subsequent steam processing is added, the processing time in the gas nitriding processing and the steam processing is 1 /
3 or less. That is, since the time required for the treatment of the film having wear resistance is relatively short, the method is excellent in mass productivity.

In the present embodiment, the shape of the oil groove on the piston surface is triangular with a groove angle of 90 ° or more, but the groove angle is about 120 to 130 °, and the corner angle is chamfered to roundness. Although it is more preferable to make the shape of a triangle, the man-hour is increased from the viewpoint of the oil film forming property of the sliding portion between the cylinder and the piston. In addition, even if the shape of the oil groove is a trapezoidal shape, the same effect as in the case of a triangular shape can be obtained.

In the present embodiment, the oil grooves having the purpose of connecting the oil grooves formed on both end surfaces of the piston are parallel to the sliding direction, but are angled with respect to the stroke direction. The same effect can be obtained as long as there is at least one point where lubricating oil can be directly supplied to the oil groove formed in the piston from the oil supply hole formed in the cylinder during the reciprocation of the piston. Is obtained. In addition, in the present embodiment, the position of the oil groove provided on the side surface near both end surfaces of the piston is 5 m from both end surfaces.
m is a triangular vertex.
The same effect can be obtained if the distance is within mm.

Although the cylinder has one oil supply hole, if the length A of the oil supply hole from the oil supply hole to the valve plate is larger than the maximum stroke length B of the piston, A plurality may be provided.

According to the present embodiment, the thickness of all the coating layers is set to 20 to 30 μm or more, but if it is less than 20 μm, the wear resistance of the piston itself cannot be ensured.

After the oil groove processing of the piston is performed, the entire surface of the piston is subjected to the gas nitriding treatment and the steam treatment. However, even if the oil groove processing is performed in a subsequent step, the wear resistance is not affected. The effect is obtained.

Although HFC-134a is used as the gas to be compressed in the present embodiment, R-407C and R-410A which do not contain chlorine in the molecule similarly to the refrigerant.
The same effect can be obtained even if a hydrocarbon gas or the like is used.

(Embodiment 3) FIG. 5 is an enlarged sectional view of the vicinity of a sliding portion between a cylinder 14 and a piston 18 according to this embodiment. Note that HFC-134a is used as the compressed gas.

As shown in FIG. 5, the cylinder 14 is formed of cast iron (JIS: FC200), and then an oil supply hole 14a is formed in the upper part of the cylinder to supply oil to a sliding portion between the cylinder 14 and the piston 18. In the processing location of the oil supply hole 14a, the length A from the oil supply hole 14a to the valve plate 16 is larger than the maximum stroke length B of the piston 15. On the other hand, the piston 18 is made of cast iron (JIS: FC20).
After processing in step 0), one oil groove 18a having an obtuse angle of 90 ° or more is formed on the surface thereof in parallel with the sliding direction of the piston 18. The oil groove 18a is formed at a position where the lubricating oil 12 can be directly supplied from the oil supply hole 14a formed in the upper part of the cylinder 14 to the oil groove 18a formed on the piston surface. Further, two oil grooves 18b having the same shape and having a triangular center at a position 5 mm from both end surfaces of the piston 18 are formed. Incidentally, the oil groove 18a is formed up to the oil groove 18b formed on both end surfaces of the piston 18,
Connect. This is because the oil groove 18a also has a role of allowing the lubricating oil 12 to reach the oil groove 18b near both end faces of the piston 18.

FIG. 6 is a partial view of the piston 18 according to the third embodiment as viewed from the side. The piston 18 is formed by processing the base material 18c as cast iron (JIS: FC200),
After forming the oil grooves 18a and 18b, the processing temperature 57
Only a salt bath nitriding treatment method to which a sulfur compound is added is performed at 0 ° C. and a treatment time of 1.5 to 2 hours, and the total film thickness is 20 to 30 μm
The nitriding layer 18d composed of the above and the sulfide coating layer 1 thereon
8e.

The lubricating oil pumped up from the oil supply pipe by a spiral oil supply structure or the like applied to the shaft is discharged from the sliding portion between the bearing and the thrust washer, and is returned to the upper portion of the cylinder before returning to the original compressor lower portion. A part of the lubricating oil is collected. The collected lubricating oil is supplied to an oil groove provided in the upper part of the piston through an oil supply hole provided in the upper part of the cylinder. The three oil grooves formed on the surface of the piston can supply lubricating oil to the sliding portion between the cylinder and the piston, especially to the side surfaces near the both end surfaces of the piston where the occurrence and progress of wear are remarkable. Therefore, the amount of lubricating oil supplied to the sliding portion between the cylinder and the piston is increased as compared with the related art, and the lubricating conditions can be improved.

For example, when a sufficient oil film is not formed on the sliding surface between the cylinder and the piston due to an extremely small amount of supplied oil, for example, immediately after the start of the compressor, the film is formed only by forming a lubricated layer on the piston surface. Since the thickness is as thin as several μm, once the abrasion due to metal contact progresses, there is a high possibility that the lubricated layer disappears instantaneously.
If only the salt bath nitriding layer is formed on the surface of the piston, the hardness of the piston material is increased to HV700 to 800, so that the wear resistance of the piston itself is improved. The possibility remains that abnormal wear may occur on the sliding surface of the cylinder. Therefore, it is not possible to improve the durability of the compressor sufficiently only by improving the wear resistance of the piston itself. However, the sulfide film layer formed on the surface of the cylinder in the present invention hardly exhibits its wear resistance in a lubricating friction region, that is, a mild wear region where normal wear is performed, but a non-lubricating friction region, that is, adhesion or adhesion. In severe wear in which thermal wear mainly appears, particularly excellent adhesion and seizure resistance are exhibited.

In the present embodiment, the sulfurized layer formed by the salt bath nitriding treatment to which a sulfur compound is added is a porous oil film forming ability such as an oxide film layer formed by performing a salt bath nitriding treatment and a steam treatment, and a slip. Although it does not have the characteristics, the same effect as or more than that of the oxide film layer can be obtained particularly with respect to anti-adhesion and wear resistance in the non-lubricated friction region. As a result, adhesive wear due to metal contact at the sliding portion between the cylinder and the piston can be prevented. Also, since only the salt bath nitriding treatment to which a sulfur compound is added is sufficient, the number of steps is smaller than the method of performing the salt bath nitriding treatment and the steam treatment to form the oxide film layer and the nitriding treatment layer. Therefore, the method is excellent in mass productivity.

Accordingly, an oil supply hole and an oil groove provided for forcibly supplying oil to a sliding portion of the cylinder and the piston,
HFC with poor lubrication performance due to the synergistic effect of double adhesion wear prevention measures by salt bath nitridation treatment with sulfur compound added to the piston surface which has adhesion resistance and seizure resistance and oil film formation property improvement Under -134a, abnormal wear and seizure of the sliding portion between the cylinder and the piston can be prevented, and the sliding loss can be reduced.

As described above, in this embodiment, the non-compressed gas is formed by using HFC-134a, a through hole is formed in the upper part of the cylinder of the compressor, and an oil groove is formed in the piston surface in the sliding direction of the piston. One, one from both ends of piston
While forming two oil lines within 0 mm and forming an oil supply path to a sliding portion between a cylinder and a piston connected to the oil groove,
Treatment temperature 570 ° C, treatment time 1.5 on all piston surfaces
Abrasion of the cylinder and piston is prevented by performing a salt bath nitriding treatment with sulfur compound added for up to 2 hours to form a nitriding layer having a total thickness of 20 to 30 μm or more and a sulfide coating layer thereon. In addition, the sliding loss can be reduced, and as a result, the durability and compression efficiency of the compressor can be improved.

In this embodiment, the shape of the oil groove on the piston surface is triangular with a groove angle of 90 ° or more, but the groove angle is about 120 to 130 °, and the corner angle is chamfered and rounded. Although the method of forming a triangular shape is necessary, although the number of steps is increased, it is desirable from the viewpoint of forming an oil film on the sliding portion between the cylinder and the piston. In addition, even if the shape of the oil groove is a trapezoidal shape, the same effect as in the case of a triangular shape can be obtained.

In the present embodiment, the oil grooves having the purpose of connecting the oil grooves formed on both end faces of the piston are parallel to the sliding direction, but are angled with respect to the stroke direction. The same effect can be obtained as long as there is at least one point where lubricating oil can be directly supplied to the oil groove formed in the piston from the oil supply hole formed in the cylinder during the reciprocation of the piston. Is obtained. In addition, in this embodiment, the position of the oil groove provided on the side surface near both end surfaces of the piston is 5 mm from both end surfaces.
Is a triangular vertex, but 10m from both end faces
Within m, the same effect can be obtained.

The cylinder has one oil supply hole. However, if the length A of the oil supply hole from the oil supply hole to the valve plate is larger than the maximum stroke length B of the piston, A plurality may be provided.

According to the present embodiment, the thickness of all the coating layers is set to 20 to 30 μm or more, but if it is less than 20 μm, the wear resistance of the piston itself cannot be secured.

After the oil groove processing of the piston is performed, the entire surface of the piston is subjected to a salt bath nitriding treatment in which a sulfur compound is added. However, even if the oil groove processing is performed in a later step, the wear resistance is not affected. The same effect can be obtained.

Although HFC-134a is used as the gas to be compressed in the present embodiment, R-407C and R-410A which do not contain chlorine in the molecule like the refrigerant.
The same effect can be obtained even if a hydrocarbon gas or the like is used.

[0057]

As described above, according to the present invention, a through hole is formed in the upper part of the cylinder of the compressor, and one oil groove is formed in the piston surface in the sliding direction of the piston.
The oil supply passage to the sliding portion between the cylinder and the piston, which is formed within 2 mm and connected to the oil groove, is formed, and the water content of NH ₃ gas is 3 to 10 on the entire surface of the piston.
% Gas nitriding and water vapor treatment to give a total film thickness of 2%.
By forming a solid solution layer containing nitrogen and oxygen of 0 to 30 μm or more and an oxide film layer thereon, it is possible to improve the lubrication and wear characteristics of the sliding portion between the cylinder and the piston. The durability and compression efficiency of the machine can be improved.

Further, a through hole is formed in the upper part of the cylinder of the compressor, and one oil groove is formed on the piston surface in the sliding direction of the piston, and two oil grooves are formed within 10 mm from both end surfaces of the piston to connect the oil grooves. Along with forming an oil supply passage to the sliding part between the cylinder and the piston, the entire surface of the piston is subjected to a salt bath nitriding treatment and a steam treatment with a treatment temperature of 500 to 600 ° C. and a treatment time of 1.5 to 2 hours, Total film thickness is 20-3
By forming a solid solution layer containing nitrogen and oxygen of 0 μm or more and an oxide film layer thereon, it is possible to improve the lubrication and wear characteristics of the sliding portion between the cylinder and the piston, and as a result, the Durability and compression efficiency can be improved.

Also, a through hole is formed in the upper part of the cylinder of the compressor, and one oil groove is formed on the piston surface in the sliding direction of the piston, and two oil grooves are formed within 10 mm from both end surfaces of the piston to connect the oil grooves. The oil supply path to the sliding portion between the cylinder and the piston was formed, and the entire surface of the piston was subjected to a salt bath nitriding treatment with a treatment temperature of 570 ° C. and a treatment time of 1.5 to 2 hours to which a sulfur compound was added. Film thickness 20-30
By forming a nitrided layer of at least μm and a sulfide film layer on it, the lubrication and wear characteristics of the sliding part between the cylinder and the piston can be improved, resulting in the durability and compression efficiency of the compressor Can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view around a sliding portion between a cylinder and a piston according to a first embodiment of the present invention.

FIG. 2 is a partial view of the piston according to the embodiment as viewed from the side.

FIG. 3 is an enlarged cross-sectional view around a sliding portion between a cylinder and a piston according to a second embodiment of the present invention.

FIG. 4 is a partial view of the piston according to the embodiment as viewed from the side.

FIG. 5 is an enlarged cross-sectional view around a sliding portion between a cylinder and a piston according to a third embodiment of the present invention.

FIG. 6 is a partial view of the piston according to the embodiment as viewed from the side.

FIG. 7 is a sectional view of a conventional compressor.

FIG. 8 is an enlarged cross-sectional view around a conventional cylinder and piston sliding portion.

FIG. 9 is a partial view of a conventional piston viewed from the side.

[Explanation of symbols]

 7, 14 Cylinder 14a Oil supply hole 8, 15, 17, 18 Piston 8a Lubrite treatment layer 15a, 17a, 18a Oil groove 15b, 17b, 18b Oil groove 15c, 17c, 18c Base material 15d Solid solution layer 17d, 18d Nitriding treatment Layers 15e, 17e Oxide layer 18e Sulfide layer

Claims (3)

[Claims] 1. A shaft connected to an electric motor, a connecting rod having a bearing at one end thereof attached to the shaft, a piston pin attached to a bearing at the other end of the connecting rod, and a piston fixed to the piston pin. And a component of the compressor comprising a cylinder integrally forming a compression chamber with the piston, wherein a through hole is formed in the upper part of the cylinder, and one oil groove is formed on the piston surface in the sliding direction of the piston. 10 from both ends of piston
In addition to forming an oil supply passage to a sliding portion between a piston and a cylinder having the oil grooves connected to each other within 2 mm and having a water content of 3 to 10% in NH ₃ gas on the surface of the piston,
Is subjected to gas nitriding and steam treatment to a total film thickness of 20
A compressor comprising a solid solution layer containing nitrogen and oxygen having a thickness of 30 μm or more and an oxide film layer formed thereon. 2. A shaft connected to an electric motor, a connecting rod having a bearing at one end attached to the shaft, a piston pin attached to a bearing at the other end of the connecting rod, and a piston fixed to the piston pin. And a cylinder integrally forming a compression chamber with the piston, wherein a through hole is formed in the upper portion of the cylinder, and one oil groove is formed on the piston surface in the piston sliding direction. 10m from both ends
m and two oil grooves are connected to form a lubricating passage to the sliding part between the cylinder and the piston, which are connected to the oil groove, and the surface of the piston is subjected to a salt bath nitriding treatment and a steam treatment, so that the total film thickness is reduced. A compressor comprising a nitrided layer having a thickness of 20 to 30 μm or more and an oxide film layer formed thereon. 3. A shaft connected to an electric motor, a connecting rod having a bearing at one end thereof attached to the shaft, a piston pin attached to a bearing at the other end of the connecting rod, and a piston fixed to the piston pin. And a cylinder integrally forming a compression chamber with the piston, wherein a through hole is formed in the upper portion of the cylinder, and one oil groove is formed on the piston surface in the piston sliding direction. 10m from both ends
m, forming a lubricating path to a sliding portion between the cylinder and the piston, the oil grooves being connected to each other, and a salt bath nitriding treatment in which a sulfur compound is added to the surface of the piston,
A compressor comprising a nitriding layer having a total thickness of 20 to 30 μm or more and a sulfide film layer formed thereon.