JP2007100517A - Hermetic compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hermetic compressor having a coated vane with sufficient sliding yield strength even against use using a natural refrigerant such as carbon dioxide as a refrigerant. <P>SOLUTION: This hermetic compressor is provided with a compression element and a motor-driven element, a driving source of this compression element in a sealed vessel, and is characterized by forming a DLC-Si coating layer 14d by applying DLC-Si processing onto a nitriding diffusion layer 14c by forming the nitriding diffusion layer 14c on the vane 14 of the compression element by applying nitriding to a base material 14b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hermetic compressor used in a refrigeration cycle and the like, and more particularly to a surface treatment that improves the wear resistance of sliding parts of the hermetic compressor.

  Conventionally, R12 (dichloro, difluoro, methane) and R22 (monochloro, difluoro, methane) have been mainly used as refrigerants for hermetic compressors used in refrigeration cycles and the like.

  When these refrigerants R12 and R22 are released into the atmosphere and reach the ozone layer over the earth, the chlorine groups contained in the refrigerant are subject to chlorofluorocarbon regulations due to the problem of destroying the ozone layer. It has been moved to HFC refrigerants that do not contain groups. However, in recent years, in order to prevent global warming, replacement of this HFC refrigerant with a natural refrigerant having a low global warming potential has been studied.

  Of the sliding parts of a rotary compressor that is an example of a hermetic compressor, the most severe sliding conditions are the vane that reciprocates in the groove of the cylinder and the eccentric part of the crankshaft. It is a contact portion with a rolling piston that is attached and rotates while contacting the inner periphery of the cylinder and the tip of the vane via an oil film and compresses the gas in the cylinder.

  Since the HFC refrigerant does not contain a chlorine atom in its molecule unlike R12, an iron chloride film having excellent wear resistance is not formed in the sliding portion. Therefore, with the introduction of the HFC refrigerant, nitriding treatment or coating is performed on the vane in order to improve the wear resistance of the vane.

Furthermore, since the compressor operating pressure is higher than that of conventional refrigerants in HFC refrigerants, particularly natural refrigerants, CrN (chromium nitride), TiN (titanium nitride), DLC (diamond-like carbon) having high wear resistance to vanes. ) Etc. tend to be applied.
Japanese Patent No. 3190541 JP 2005-155650 A

  However, the CrN coating has good adhesion strength of the film, wear resistance of the film, and slidability. However, the attack (wear) to the mating material (the vane mating material is the rolling piston) and the peeling of the film are sufficient. I can't say that. The same applies to the TiN coating. Furthermore, although the DLC coating has good film wear and sliding properties and good attack on the mating material, it cannot be said that the film adhesion strength and the film peeling are sufficient. In short, the conventional coating is insufficient as a coating applied to a vane used under high pressure conditions in applications such as natural refrigerants.

  The present invention has been made to solve the above-described problems, and is a sliding component provided with a coating having a sufficient sliding resistance even for an application using a natural refrigerant such as carbon dioxide as a refrigerant. It aims at providing the hermetic compressor provided with.

  A hermetic compressor according to the present invention is a hermetic compressor having a compression element and an electric element serving as a drive source for the compression element in a hermetic container, and at least one of sliding parts of the compression element, A nitriding treatment is performed on the base material to form a nitriding diffusion layer, and a DLC-Si treatment is further performed on the nitriding diffusion layer to form a DLC-Si coating layer.

  The hermetic compressor according to the present invention is a hermetic compressor provided with a sliding component having a coating having sufficient sliding resistance even for applications using a natural refrigerant such as carbon dioxide as a refrigerant. A compressor is obtained.

Embodiment 1 FIG.
1 to 7 are diagrams showing Embodiment 1, FIG. 1 is a longitudinal sectional view of a rotary compressor, FIG. 2 is a sectional view showing a contact state between a vane and a rolling piston, and FIG. 3 is a perspective view of the vane. 4 is a cross-sectional view of the vane, FIG. 5 is an explanatory diagram of the DLC-Si coating, FIG. 6 is a diagram comparing the characteristics of the conventional coating and the DLC-Si coating, and FIG. 7 is a diagram illustrating the characteristics of various refrigerants. .

  As shown in FIG. 1, a rotary compressor (an example of a hermetic compressor) includes a compression element 10 in a hermetic container 4 including a body 1, an upper dish container 2, and a lower dish container 3, The electric element 13 and refrigerating machine oil (not shown) are accommodated. The compression element 10 includes an upper bearing 6 (an example of a sliding part), a lower bearing 7 (an example of a sliding part) that closes both ends of a cylinder 5 (an example of a sliding part) that forms a compression chamber therein, Consists of a rolling piston 9 (an example of a sliding part) that fits in an eccentric portion of a drive shaft 8 (an example of a sliding part), a vane that reciprocates in a groove of the cylinder 5 and whose tip contacts the rolling piston 9. Is done. The electric element 13 includes a stator 12 fixed to the body portion 1 and a rotor 11 that rotates inside the stator 12.

  As shown in FIG. 2, the vane 14 (an example of a sliding part) is pressed against the rolling piston 9 by a pressure difference between the vane spring 15 and the cylinder 5 inside and outside. In the rotary compressor, when the vane 14 reciprocates along the groove 16 of the cylinder 5 in accordance with the eccentric rotational movement of the rolling piston 9, the tip of the vane 14 has the spring force of the vane spring 15 and the cylinder. 5 slid with the outer peripheral surface of the rolling piston 9 in a state of being biased by the pressure difference between the inside and the outside, so that the tip of the vane 14 and the outer peripheral surface of the rolling piston 9 are worn. Further, since the side surface of the vane 14 slides in contact with the groove 16 of the cylinder 5 and the sliding surfaces of the upper bearing 6 and the lower bearing 7, the side surface of the vane 14 is also worn. Furthermore, since the drive shaft 8 slides with the bearing portions of the upper bearing 6 and the lower bearing 7 that support the rotation of the drive shaft 8, the drive shaft 8 and the bearing portion are worn.

  Therefore, in order to reduce the wear of each sliding portion, refrigeration oil is stored in the sealed container 4, and the refrigeration oil (not shown) is supplied to each sliding portion to lubricate and reduce the wear. Let

  As shown in FIG. 3, the vane 14 has a circular arc shape at a contact portion 14 a with the rolling piston.

  As shown in the refrigerant characteristic comparison table of FIG. 7, in an application in which carbon dioxide gas is used as the refrigerant, the operating pressure is about 10 MPa (maximum 14 MPa) which is about five times R22, and each sliding part of the rotary compressor However, the sliding condition between the tip of the vane 14 and the outer peripheral surface of the rolling piston 9 becomes strict.

  In the present embodiment, a DLC-Si (diamond-like carbon-silicon) coating is applied to the vane 14 to improve the wear resistance of the vane 14 and the rolling piston 9 as a counterpart material.

  The vane 14 shown in FIG. 4 is formed by nitriding a base material 14b (material is high-speed tool steel: SKH51 (JIS)) to form a nitrided diffusion layer 14C (80 μm), and a DLC-Si coating thereon. Layer 14d (3 μm) is formed. As shown in FIG. 5, the DLC-Si coating layer 14d is amorphous carbon containing silicon, and has a surface layer hardness of 2500 Hmv and a film thickness of 3 μm.

  The reason for the nitriding treatment is to reduce the hardness difference from the coating layer and increase the adhesion strength of the film, and is a method generally performed for other coatings.

  Normally, the nitriding process and the coating process are performed separately, but in this embodiment, the processes from nitriding to coating are continuously performed in the same apparatus. For this reason, it is difficult for impurities to adhere to the surface of the workpiece that easily affects the adhesion strength of the DLC-Si film, and stable treatment can be performed.

In the conventional DLC process, only a film having a thickness of 1 μm could be generated and the adhesion strength was low, whereas in the DLC-Si process, the residual stress of the film itself can be reduced by containing Si. Thus, a film having a high adhesiveness and a thickness of about 10 μm at the maximum can be generated.
The Si concentration contained in the film is desirably 10 to 25%.

  As shown in FIG. 6, DLC-Si is not as excellent in adhesion strength of the film as CrN or TiN, but has very good slidability and little attack on the mating material (the mating material is less worn). In addition, since there is little risk of peeling of a wide range of the film at once, if the DLC-Si coating is applied to the sliding parts of the rotary compressor, the life of the rotary compressor can be extended.

A carbon dioxide (CO ₂ ) refrigerant having a high operating pressure (up to 14 MPa) is used. For example, a base 14b (material is a high-speed tool steel: SKH51 (JIS)) in a vane 14 of a rotary compressor for a water heater. A nitrided diffusion layer 14C (80 μm) is formed by performing nitriding treatment, and a DLC-Si coating layer 14d (3 μm) is further formed thereon. Among the sliding parts of the rotary compressor, the sliding between the tip of the vane 14 and the outer peripheral part of the rolling piston 9 which are in the boundary lubrication state is the most severe on condition, and the SKH 51 used in the conventional rotary compressor is used as it is. However, it is difficult to ensure sufficient sliding strength only by nitriding treatment, but by using the vane 14 subjected to DLC-Si treatment, a water heater using a carbon dioxide (CO ₂ ) refrigerant is used. There is almost no wear even under such severe sliding conditions.

  The DLC-Si film is worn about 0.5 to 1 μm in the initial sliding. However, since the coefficient of friction is as small as 0.1 or less thereafter, the wear hardly progresses and a stable sliding state can be maintained over a long period of time.

  The DLC-Si film has wear and peeling in a state where the surface pressure is high to some extent. The state where the surface pressure is high occurs due to the tendency of the corners to swell when the shape accuracy of the vane 14 or the rolling piston 9 varies or when nitriding is performed. Abrasion and peeling can be taken only at the periphery of the portion where the surface pressure is high, and there is no chain peeling over a wide area. Moreover, since wear or peeling occurs in part, the state of high surface pressure is partially eliminated, so wear and peeling hardly proceed.

By forming the DLC-Si film on the vane 14, sufficient wear resistance can be maintained even during sliding under a high-pressure refrigerant such as a carbon dioxide (CO ₂ ) refrigerant.

  Since the friction coefficient of the DLC-Si film is as low as 0.1 or less, it is difficult to wear the rolling piston 9 of the mating member, and the problem of performance degradation of the rotary compressor due to wear of the outer diameter of the rolling piston 9 is unlikely to occur.

  Since the DLC-Si film is difficult to peel over a wide area at a time, even if there is a partial increase in surface pressure, only the portion with high surface pressure will wear and peel, and the high surface pressure will be repaired automatically. Is done. For this reason, long-term reliability can be ensured without suddenly reaching the end of life due to wide-area peeling.

  Since the DLC-Si film can be coated on the entire surface of the component, wear suppression and seizure can be prevented not only for the tip of the vane 14 but also for sliding between the side surface of the vane 14 and the groove 16.

  In the above, the example in which the DLC-Si film is mainly applied to the vane 14 has been described. However, by applying the DLC-Si film to other sliding parts, for example, the upper bearing 6, the lower bearing 7, and the drive shaft 8, respectively. The wear resistance can be improved.

  As described above, the rotary compressor has been described as an example. However, the sliding parts of other scroll compressors and reciprocating compressors are subjected to nitriding treatment to form a nitriding diffusion layer, and further on the nitriding diffusion layer. A DLC-Si treatment may be applied to form a DLC-Si coating layer, and the same effect is obtained.

It is a figure which shows Embodiment 1, and is a longitudinal cross-sectional view of a rotary compressor. It is a figure which shows Embodiment 1, and is sectional drawing which shows the contact state of a vane and a rolling piston. FIG. 5 shows the first embodiment, and is a perspective view of a vane. FIG. 5 shows the first embodiment, and is a cross-sectional view of a vane. It is a figure which shows Embodiment 1 and is explanatory drawing of DLC-Si coating. It is a figure which shows Embodiment 1, and is the figure which compared the characteristic of the conventional coating and DLC-Si coating. It is a figure which shows Embodiment 1, and is a figure which shows the characteristic of various refrigerant | coolants.

Explanation of symbols

  1 body part, 2 upper dish container, 3 lower dish container, 4 closed container, 5 cylinder, 6 upper bearing, 7 lower bearing, 8 drive shaft, 9 rolling piston, 10 compression element, 11 rotor, 12 stator, 13 electric element , 14 vane, 14a contact part with rolling piston, 14b base material, 14c nitrided diffusion layer, 14d DLC-Si coating layer, 15 vane spring, 16 groove.

Claims (5)

In a hermetic compressor having a compression element and an electric element serving as a drive source for the compression element in a hermetic container,
At least one of the sliding parts of the compression element is subjected to nitriding treatment on the base material to form a nitriding diffusion layer, and further subjected to DLC-Si (diamond-like carbon-silicon) treatment on the nitriding diffusion layer, A hermetic compressor in which a DLC-Si coating layer is formed.   A vane, which is one of the sliding parts of the compression element, is subjected to nitriding treatment to form a nitriding diffusion layer, further subjected to DLC-Si treatment on the nitriding diffusion layer, and a DLC-Si coating layer The hermetic compressor according to claim 1, wherein:   The hermetic compressor according to claim 1 or 2, wherein the concentration of Si contained in the DLC-Si coating layer is 10 to 25%.   The hermetic compressor according to any one of claims 1 to 3, wherein the nitriding process and the DLC-Si process are continuously performed in the same apparatus.   The hermetic compressor according to any one of claims 1 to 4, wherein carbon dioxide is used as the refrigerant.

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