JP2007321676A - Rotary compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent wear and seizure of a vane tip and a rolling piston outer circumference part of a rotary compressor. <P>SOLUTION: This rotary compressor employs the rolling piston formed out of cast iron or alloy steel containing at least one or more of Cr, Mo, and Ni as composition elements, a vane formed out of iron material containing Cr and Ni as composition elements and having coating containing Cr and CrNi alloy (alloy ratio (mass%) of Cr and Ni=3:1) as composition elements applied on a surface thereof, or a vane formed out of iron material containing Cr and Ni as composition elements, having nitriding treatment applied on a surface thereof and having coating containing Cr and CrNi alloy (alloy ratio (mass%) of Cr and Ni=3:1) as composition elements applied moreover on a surface thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention particularly relates to a rotary compressor capable of suppressing the amount of wear of a sliding portion.

Conventionally, in order to ensure the reliability of a rotary compressor, it has been an important issue to suppress the amount of wear between the vane that is the sliding portion and the piston, roller, cylinder, etc. In order to improve the properties, as a method of improving the hardness of the vane, a nitriding treatment or a coating treatment after nitriding treatment has been performed.
For example, there is a compressor in which a nickel chromium plating layer is formed on the surface of a vane made of an iron-based material (for example, Patent Document 1).
Further, in a compressor for HFC (hydrofluorocarbon) refrigerant, a compound of Cr and nitrogen (N) is formed by nitriding treatment on the surface of a vane formed of steel or cast iron containing at least chromium (Cr), and at least Cr , A roller formed of cast iron or alloy steel containing any one or more of molybdenum (Mo) and nickel (Ni) is heat treated to a hardness of HRC 40 or higher, and the cylinder is cast iron containing graphite, sintered alloy, It is disclosed that the surface is formed of any of sintered alloys obtained by applying or diffusing a lubricious organic material (for example, Patent Document 2).

JP-A-63-100292 JP 10-141269 A ([0033] and others)

In rotary compressors using conventional refrigerants, solid lubricity is emitted by the chloride protective film by chlorine atoms in the refrigerant, and the formation of a plating layer on the vane surface as described above is expected to improve wear resistance. However, in recent years when HFC (hydrofluorocarbon) and natural refrigerants are being used in refrigerants, both HFC and natural refrigerants do not contain chlorine atoms in the refrigerant. Since a protective film is not formed, it is a further important issue to prevent the sliding portion from being worn or seized.
In particular, in a carbon dioxide (CO ₂ ) refrigerant, which is one of natural refrigerants, the operating pressure is about three times that of the R410A refrigerant that operates at the highest pressure in the HFC, and therefore the sliding conditions are severe. On the other hand, in the rotary compressor using HFC as a refrigerant as described above, high-speed tool steel subjected to nitriding treatment is generally applied to the vane material, but even the vane subjected to this hardening treatment, When applied to a rotary compressor using a CO ₂ refrigerant, there is a concern that the tip of the vane is significantly worn, and the sliding portion between the tip of the vane and the outer peripheral portion of the rolling piston is significantly worn due to insufficient hardness of the vane, resulting in seizure.
As described above, when a refrigerant having a high operating pressure such as CO ₂ is applied to a rotary compressor, the vane subjected only to the nitriding treatment is likely to be worn or seized. There was concern about the film peeling.

  The present invention was made to solve the above-described problems, and by applying a coating to the vane that is a sliding part, the vane is made harder, the amount of wear is suppressed, and the coating film is further provided. The purpose is to ensure the reliability until the product life of the rotary compressor by preventing the peeling of the rotary compressor.

A rotary compressor according to the present invention includes a cylinder having a refrigerant intake portion in a radial direction, a rolling piston accommodated in a cylindrical inner surface portion of the cylinder so as to be eccentrically rotatable, and an eccentric portion on an inner peripheral surface of the rolling piston. Is inserted and rotated, and the outer peripheral surface of the rolling piston is eccentrically rotated while being in sliding contact with the inner peripheral surface of the cylinder. The crankshaft is reciprocally accommodated in the radial direction of the cylinder, and the distal end thereof is the outer peripheral surface of the rolling piston. A rotary compressor that compresses the refrigerant supplied to the inside of the cylinder, wherein the rolling piston is a cast iron or alloy containing at least one of Cr, Mo, and Ni as a constituent element Made of steel, the vane contains CrN and CrNiN alloy (alloy ratio of Cr to Ni (mass%) = 3: 1) as constituent elements It is characterized by being an iron-based material containing Cr and Ni on which a coating film is applied.
The vane is characterized in that a nitride layer is provided between the vane and the coating film.

  Further, carbon dioxide is used as a refrigerant in the rotary compressor according to the present invention.

  According to this invention, the vane of the rotary compressor is made of an iron-based material containing Cr and Ni as its constituent elements, and Cr and CrNi alloy (the alloy ratio of Cr and Ni (mass%) = 3: 1), or after nitriding the vane, a coating containing Cr and a CrNi alloy (Cr: Ni alloy ratio (mass%) = 3: 1) was applied. Therefore, even if a carbon dioxide refrigerant having a high operating pressure is used, the amount of wear at the tip of the vane sliding with the rolling piston can be suppressed, and further the peeling of the coating film formed on the vane surface can be suppressed.

Embodiment 1 FIG.
1 is a longitudinal sectional view of a rotary compressor according to the present invention, and FIG. 2 is a transverse sectional view of a cylinder portion corresponding to the AA ′ portion in FIG. 1, so that the eccentricity of the crankshaft 5 can be understood. The position of 5 is indicated by a broken line. In the figure, a rotary compressor 1 contains an electric motor unit 3 and a compression mechanism unit 4 driven by the electric motor unit 3 in a hermetic container 2, and is compressed by a crankshaft 5 driven to rotate by the electric motor unit 3. It has a structure in which the mechanism part 4 operates. The electric motor unit 3 includes a stator 6 fixed in the sealed container 2 by press-fitting and the like, and a rotor 7 accommodated in the stator 6 so as to be concentrically rotatable. Are fixed concentrically.
On the other hand, the compression mechanism 4 has a cylinder 8 fixed by press-fitting or the like in the sealed container 2, and the upper and lower ends of the cylinder 8 are sandwiched between the upper bearing 10 and the lower bearing 11, respectively, and the lower part of the crankshaft 5 is While being supported rotatably, the upper and lower ends of the opening of the cylinder chamber 8a are hermetically closed.

In FIG. 2, the cylinder 8 has a cylindrical inner surface, and an annular rolling piston 12 is accommodated in the inner cylinder chamber 8a so as to be eccentrically rotatable. An eccentric portion 5a of the crankshaft 5 is fitted into the annular space portion of the rolling piston 12, and the rolling piston 12 rotates eccentrically in the cylinder chamber 8a by the rotation of the crankshaft 5.
The cylinder 8 is provided with a vane groove 13 formed in the radial direction so as to communicate with the cylinder chamber 8a, and a suction port 16 formed so as to communicate with the cylinder chamber 8a and the outside of the annular cylinder 8. Is done. The refrigerant (CO ₂ refrigerant having a high operating pressure in the present embodiment) supplied from the suction port 16 into the cylinder chamber 8 a is compressed by the eccentric rotation of the rolling piston 12 and discharged from the upper bearing 10. After being discharged into the sealed container 2 from the outlet (not shown), the refrigerant is discharged from the discharge pipe 9 to the outside.
The vane groove 13 accommodates a vane 15 and a vane spring 14 that always elastically presses the vane 15 from the back surface toward the rolling piston 12, and the tip 15 a of the vane 15 is placed on the outer peripheral wall of the rolling piston 12. By always slidably and slidably contacting the vane 15, the vane 15 reciprocates vertically in the vane groove 13 as indicated by an arrow X in the figure, while the cylinder chamber 8a is moved to the high pressure side and the low pressure side. It is designed to be divided and sealed.
Thus, during the operation of the compressor, the vane always wears by sliding with the outer peripheral wall of the rolling piston 12.

  Here, the material of the rolling piston 12 and the vane 15 will be described. The rolling piston 12 is made of cast iron or alloy steel containing at least one of Cr, Mo, and Ni as its constituent elements, and the surface hardness of the rolling piston 12 is about HV700 in terms of Vickers hardness. The vane 15 uses an iron-based material containing Cr and Ni as its constituent elements, such as stainless steel, stainless cast steel, heat-resistant steel cast steel, nickel chrome molybdenum steel, and the like, and performs a desired treatment.

Next, the configuration of the vane 15 according to the present invention will be described with reference to the drawings. As described above, the vane 15 uses an iron-based material containing Cr and Ni as its constituent elements, such as stainless steel, stainless cast steel, heat-resistant steel cast steel, nickel chrome molybdenum steel, and the like. A coating film 15c containing Cr and CrNi alloy as elements is formed. Examples of the coating film 15c containing Cr and a CrNi alloy as constituent elements include a Cr—Ni—N nitride film. Examples of the Cr—Ni alloy include Cr ₃ NiN, CrNiN, and CrNi ₃ N depending on the Ni content.
As a film forming method including Cr and Cr ₃ NiN, CrNiN, CrNi ₃ N, etc., here, as a kind of physical vapor deposition (PVD), an arc ion plating (AIP) apparatus is used to form Cr-Ni. A -N nitride film was deposited. As the cathode target, Cr and CrNi alloy (Cr and Ni alloy ratio (mass%) = 3: 1, 1: 1, 1: 3) were used. When the Cr / Ni alloy ratio of the CrNi alloy is 3: 1, Cr ₃ NiN is produced. When it is 1: 1, CrNiN is produced, and when it is 1: 3, CrNi ₃ N is produced. Vapor deposition uses a magnetic field induction evaporation source (super cathode) to form a high-quality film with a small surface roughness. For example, an arc current of 100 A, a bias voltage of 40 V, and a high-purity N ₂ gas atmosphere Vapor deposition was performed at a medium pressure (total pressure of about 2.5 Pa). During deposition, the vane is heated to about 500 ° C., and nitrogen diffuses into the base material of the vane to form a Cr—Ni—N nitride inside the base material. On the other hand, the coating is also a Cr-Ni-N nitride film, and the Cr-Ni-N nitride suppresses the hardness difference between the base material and the coating film, and also due to the connection between the Cr-Ni-N nitrides. The adhesion between the base material and the coating film is improved. The thickness of the coating film 15c is desirably about 3 ± 1 μm. When it is thinner than 1 μm, the effect of wear resistance is not achieved, and when it is thicker than 10 μm, the shearing force in the film increases, and there is a concern about peeling from the base material.
The vane comprised above was used for the rotary compressor shown in FIG.

Next, a wear test was performed in order to confirm the wear resistance of the vane after film formation.
FIG. 4 shows the wear test conditions, and FIG. 5 shows the results. The abrasion test was performed by pressing the vane 15 against the rolling piston 12 and rotating the rolling piston 12. The test conditions are as shown in FIG. 4, but all were performed using refrigeration oil. All rolling pistons use MoNiCr cast iron, vane material is prepared with conventional SKH51 and stainless steel according to the present invention, SKH51 is nitrided as before, stainless steel is CrN coated (Ni content is 0) As Comparative Example 1, three examples according to the present invention were prepared. The thickness of the coating film on the stainless steel surface is about 3 μm.
FIG. 5 shows a relative comparison result of the total wear amount obtained by adding the wear amount of the rolling piston and the wear amount of the vane 15. The vane material SKH51 has a hardness of HV670, and stainless steel has a hardness of HV320. From the conventional nitriding treatment of SKH51, it can be seen that coating with stainless steel significantly reduces the amount of wear. Furthermore, the total wear of the vane and rolling piston is less when the vane is coated with Cr and Cr ₃ NiN than the total wear of the vane and rolling piston when the vane is coated with CrN. When CrN was used as a vane coating, the aggressiveness of the vane against the rolling piston was great and the wear of the rolling piston was great. When the CrNiN coating is applied to the vane and the CrNi ₃ N coating, the vane and rolling piston have a large total wear because the vane surface hardness is low and the vane wear is large. From the results of FIG. 5, it is understood that it is effective to coat the vane with CrN and Cr ₃ NiN.
Moreover, it was found that the vanes obtained by coating the stainless steel with a coating film did not show any peeling after the sliding test and had sufficient adhesion strength.

Embodiment 2. FIG.
In Embodiment 1 described above, nitrogen diffused into the vane material during the formation of the coating film, which contributed to the improvement of the adhesion. In the present embodiment, an embodiment in which nitriding treatment is performed before the coating film is formed will be described. .
As in the first embodiment, the rolling piston 12 is made of cast iron or alloy steel containing at least one of Cr, Mo, and Ni as a constituent element, and the surface hardness of the rolling piston 12 is about Vickers hardness. HV700. On the other hand, a vane is prepared containing Cr and Ni as constituent elements, and the vane surface is subjected to nitriding treatment. By performing the nitriding treatment, it is possible to improve the hardness of the vane surface and also increase the amount of nitrogen diffusion, so that the amount of Cr—Ni—N nitride inside the vane can be increased. Accordingly, it is possible to further improve the adhesion between the coating film 15c formed in the coating performed after the nitriding treatment and the base material.
Examples of the nitriding method include ion nitriding. When a compound layer is formed on the surface of the vane in the nitriding treatment, the coating film 15c formed by the coating applied after the nitriding treatment is liable to be peeled off. Therefore, a method in which the compound layer is not formed on the surface is used in the nitriding treatment. It is desirable. Further, when the compound layer is formed, the same effect can be obtained by removing the compound layer by lapping or the like and then coating it.

Next, a coating film 15c containing Cr and CrNi alloy as constituent elements is formed on the vane surface 15b subjected to nitriding by coating.
In general, when coating is performed, if the hardness difference between the base material and the coating film 15c is large, peeling of the coating film 15c is likely to occur. At this time, in order to suppress peeling of the coating film 15c, nitriding treatment is often performed before coating. The nitriding treatment improves the hardness of the base material and reduces the hardness difference between the coating film 15c and the base material, and thus has an effect of suppressing the peeling of the coating film 15c. In addition, when an iron-based material containing Cr and Ni as constituent elements is used for the vane material, the nitrogen diffused on the surface of the base metal reacts with Cr and Ni contained in the base material when nitriding is performed. Cr—Ni—N nitride is formed. Also in coating, a coating film 15c containing Cr and a CrNi alloy as constituent elements is formed on the surface of the base material. What is a Cr—Ni—N nitride formed by nitriding and a coating film formed by coating? Since they are the same or similar compounds, it is possible to further improve the adhesion and to suppress the peeling of the coating film 15c.

  The nitriding treatment was subjected to the same wear test as in the first embodiment, but the same result was obtained. Moreover, no peeling was observed, and the adhesion was good.

It is a longitudinal cross-sectional view which shows the structure of the rotary compressor used for this invention. It is a cross-sectional view of the cylinder part in FIG. It is a figure which shows the structure of the vane used for the rotary compressor by Embodiment 1 of this invention. It is a figure which shows the conditions of the abrasion test between the vane and rolling piston by this Embodiment 1. FIG. It is a figure which shows the abrasion resistance of the vane by Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary compressor, 2 Airtight container, 3 Electric motor part, 4 Compression mechanism part,
5 Crankshaft, 5a Eccentric part, 6 Stator, 7 Rotor,
8 cylinder, 8a cylinder chamber, 9 discharge pipe, 10 upper bearing,
11 Lower bearing, 12 Rolling piston, 13 Vane groove,
14 vane spring, 15 vane, 15a vane tip,
15b Nitrogen diffusion layer, 15c coating film, 16 suction port.

Claims (3)

A cylinder having a refrigerant intake in the radial direction;
A rolling piston housed in a cylindrical inner surface of the cylinder so as to be eccentrically rotatable;
A crankshaft whose eccentric part is fitted on the inner peripheral surface of the rolling piston and rotates eccentrically while sliding the outer peripheral surface of the rolling piston in contact with the inner peripheral surface of the cylinder;
A vane that is reciprocally housed in the radial direction of the cylinder and whose tip is pressed against the outer peripheral surface of the rolling piston,
In the rotary compressor for compressing the refrigerant supplied into the cylinder,
The rolling piston is made of cast iron or alloy steel containing at least one of Cr, Mo, Ni as a constituent element,
The vane is an iron-based material containing Cr and Ni with a coating film containing CrN and a CrNiN alloy (alloy ratio (mass%) of Cr: Ni = 3: 1) as constituent elements. A featured rotary compressor. The rotary compressor according to claim 1, wherein the vane is made of an iron-based material subjected to nitriding treatment and includes a nitride layer between the vane and the coating film. The rotary compressor according to claim 1 or 2, wherein the refrigerant is carbon dioxide.

Images