JP2005155642A - Rotary compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary compressor with high reliability by preventing rollers and vanes from being abnormally worn by using polyalkylene glycol or polyalphaolefin as the base oil of lubricating oil in the compressor in which carbon dioxide as natural refrigerant is used for refrigerant. <P>SOLUTION: In this rotary compressor, carbon dioxide is used as the refrigerant, and polyalkylene glycol (nominal name) or polyalphaolefin (nominal name) or a mineral oil is used as the base oil of the lubricating oil. The rotary compressor uses the vanes having a radius of curvature Rv (cm) at its slidable contact part with the rollers of the vanes expressed by the following expression 1. The expression 1 is shown by T<Rv<Rr, where, in the expression 1, T is the thickness (cm) of the vanes, and Rr is the radius of curvature (cm) on the outer periphery of the rollers in slidable contact with the vanes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotary compressor using a natural refrigerant. More specifically, the present invention relates to a configuration of a roller and a vane that is suitable for preventing abnormal wear of rollers and vanes and providing a highly reliable rotary compressor. It is about.

  Refrigerators, vending machines, compressors for showcases, and compressors used for household and commercial air conditioners have conventionally used dichlorodifluoromethane (R12) and monochlorodifluoromethane (R22) as refrigerants. R12 and R22 are subject to Freon regulation due to the problem of destroying the ozone layer when released into the atmosphere and reaching the ozone layer over the earth due to the potential of ozone destruction. This destruction of the ozone layer is caused by chlorine groups (Cl) in the refrigerant. Therefore, refrigerants that do not contain chlorine groups, for example, HFC refrigerants such as R32, R125, and R134a, hydrocarbon refrigerants such as propane and butane, and natural refrigerants such as carbon dioxide and ammonia are considered as alternative refrigerants. .

  FIG. 1 shows a cross-sectional structure of a two-cylinder rotary compressor to which the present invention is applied, FIG. 2 is a cross-sectional explanatory view showing the relationship among cylinders, rollers, vanes, etc., and FIG. The rotary compressor denoted by reference numeral 1 as a whole includes a cylindrical sealed container 10, and an electric motor 20 and a compression device 30 accommodated in the sealed container 10. The electric motor 20 includes a stator 22 and a rotor 24 fixed to the inner wall portion of the hermetic container 10, and a rotating shaft 25 attached to the center of the rotor 24 includes two plates that close the openings of the cylinders 31 and 32. 33 and 34 are rotatably supported. A crank portion 26 provided eccentrically is formed on a part of the rotating shaft 25. Cylinders 31 and 32 are disposed inside the two plates 33 and 34. The cylinders 31 and 32 (hereinafter referred to as the cylinder 32) have the same axis as the axis of the rotary shaft 25. A refrigerant suction port 23 and a discharge port 35 are provided in the peripheral wall portion of the cylinder 32.

  A ring-shaped roller 38 is provided in the cylinder 32, and the inner peripheral surface 38 B of the roller 38 is in contact with the outer peripheral surface 26 A of the crank portion 26, and the outer peripheral surface 38 A of the roller 38 is the inner peripheral surface 32 B of the cylinder 32. To touch. A vane 40 is slidably provided on the cylinder 32, and the tip of the vane 40 comes into contact with the outer peripheral surface 38 </ b> A of the roller 38. The vane 40 is urged toward the roller 38, and the compressed refrigerant is introduced into the back surface of the vane 40 to ensure the seal between the vane tip and the roller 38. A compression chamber 50 is formed by being surrounded by the vane 40, the roller 38, the cylinder 32, the plate 34 that closes the cylinder 32, and the like. In the rotary compressor 1, for example, a polyol ester or polyvinyl ether is used as a base oil as a lubricating oil.

  Therefore, when the rotating shaft 25 rotates counterclockwise in FIG. 2, the roller 38 also rotates eccentrically in the cylinder 32, and the refrigerant gas sucked from the suction port 23 is compressed and discharged from the discharge port 35. In this suction-compression-discharge stroke, a pressing force Fv is generated at the contact portion between the roller 38 and the vane 40.

Conventionally, the contact surface 40A with the outer peripheral surface 38A of the roller 38 at the tip of the vane 40 is formed in an arc shape having a curvature radius Rv. The radius of curvature Rv has a value substantially equal to the width dimension T of the vane 40 and is about 1/10 to 1/3 of the radial dimension of the roller 38. And, as the material of the roller 38, cast iron or alloy cast iron is subjected to quenching, and as the material of the vane 40, stainless steel or tool steel or those subjected to surface treatment such as nitriding treatment are mainly used. In particular, it was common to impart high hardness and toughness to the vane material. (See Patent Document 1 and Patent Document 2)
JP-A-10-141269 JP 11-217665 A

The contact state between the roller 38 and the vane 40 can be replaced by a contact problem between cylinders having different curvatures, as shown in FIG. In such a state, when the two elastic bodies of the roller 38 and the vane 40 are pressed by the pressing force Fv of the vane 40, they generally make surface contact instead of point or line contact, and the elastic contact surface length at that time d is calculated by the above formula (7), and a Hertz stress Pmax (kgf / cm ² ) expressed by the following formula (9) is generated at the contact portion (hertz elastic contact theory).

Pmax = 4 / π · Fv / L / d Equation (9)
(Fv, L, and d in Formula (9) are the same as those in Formula (6) and Formula (7))
When the surface contact is increased and the Hertz stress is increased in this manner, the vane of the rotary compressor using the refrigerant not containing chlorine in the molecule and using the polyol ester or the polyvinyl ether as the base oil as the lubricating oil is resistant to wear. Surface treatment such as nitriding and CrN ion coating is performed to improve the properties, but the nitriding treatment does not have sufficient strength, and CrN ion coating has a risk of peeling of the coating layer At the same time, there were drawbacks such as high production costs.

  The present invention has been made to solve the problems of the related art, and in a compressor using a natural refrigerant as a refrigerant, abnormal wear of rollers and vanes is prevented, and a highly reliable rotary compressor The purpose is to provide.

  As a result of diligent research to solve the problem, the curvature radius of the contact surface with the outer peripheral surface of the roller at the tip of the vane has been changed to a value almost equal to the width dimension of the vane. In the rotary compressor using carbon dioxide, the radius of curvature is made larger than the width dimension of the vane within the range of securing the sliding contact surface at the sliding contact portion between the vane and the roller, and polyalkylene glycol or poly By using alpha olefin or mineral oil as the base oil, the Hertzian stress can be reduced and the sliding distance is increased to disperse the stress and lower the temperature at the sliding contact portion between the vane and the roller. Even without expensive coating treatment, even with inexpensive nitriding treatment (NV nitriding, nitronitriding, radical nitriding) Is effective to reduce the wear of the surface and the vane, to prevent abnormal wear of the roller and the vane, was led to form a present invention found that high reliability can be provided a rotary compressor.

  In order to solve the problems, the rotary compressor according to claim 1 of the present invention includes a refrigeration circuit in which a compressor, a condenser, an expansion device, an evaporator, and the like are sequentially connected by piping, and uses a natural refrigerant. A cylinder having a suction port and a discharge port, a rotary shaft having a crank portion disposed on an axis of the cylinder, a roller disposed between the crank portion and the cylinder and rotating eccentrically, and a cylinder And a compound layer mainly composed of Fe and S is formed on the outermost surface of the vane by nitriding, and a Fe—N layer is formed below the vane. It is characterized by being treated by a nitriding treatment for forming a diffusion layer mainly composed of.

  According to a second aspect of the present invention, in addition to the seventh aspect, the rotary compressor forms a compound layer mainly composed of Fe and S on the outermost surface of the vane by nitriding, and mainly comprises Fe-N under the nitriding treatment. A nitriding treatment for forming a diffusion layer is performed, and the compound layer mainly composed of Fe and S on at least the side surface of the vane is removed.

  Further, in order to secure a sliding surface at the sliding contact portion of the vane with the roller, the eccentric amount (cm) of the rotation center (O1) and the roller center (O2) of the rotation shaft is set to E, and the curvature radius (Rv) of the vane. The angle between the straight line (L1) connecting the center (O3) and the roller center (O2) and the straight line (L2) connecting the center (O3) and the rotation center (O1) is α, and the straight line (L1) is the roller When the sliding distance between the point intersecting the outer peripheral surface and the point where the straight line (L2) intersects the outer peripheral surface of the roller is ev, T, Rv, Rr, E, α, ev are expressed by the following equations (2) to ( It may be in the relationship represented by 4).

T> 2 · Rv · E / (Rv + Rr) Formula (2)
sin α = E / (Rv + Rr) Formula (3)
ev = Rv · E / (Rv + Rr) Formula (4)
In addition, in consideration of elastic contact during high-load operation, the height of the vane is set to L (cm) and the longitudinal elastic modulus of the vane and roller is set to ensure a sliding surface at the sliding contact portion of the vane with the roller. E1 and E2 (kgf / cm ² ), vane and roller Poisson's ratios ν1 and ν2, respectively, design pressure ΔP (kgf / cm ² ), and the equivalent radius (cm) calculated by equation (5) where ρ is the pressing force of the vane calculated by the equation (6) is Fv (kgf), and the elastic contact surface length calculated by the equation (7) is d (cm) using these, T, Rv, Rr, E, d may be in a relationship represented by the following formula (8).

T> [2.Rv.E / (Rv + Rr)] + d Formula (8)
[However, in Formula (8), T, Rv, Rr, and E represent the same as Formula (1) and Formula (2). ]

Further, the vane is formed of an iron-based material having a longitudinal elastic modulus of 1.96 × 10 ^{5 to} 2.45 × 10 ⁵ N / mm ² .

  Alternatively, the treatment may be performed by a nitriding treatment in which a compound layer mainly composed of Fe and N is formed on the outermost surface of the vane and a diffusion layer mainly composed of Fe and N is formed thereunder.

  Alternatively, the vane surface may be treated by a nitriding process in which only a diffusion layer mainly composed of Fe and N is formed.

  Further, a nitriding treatment is performed in which a compound layer mainly composed of Fe and N is formed on the outermost surface of the vane, and a diffusion layer mainly composed of Fe and N is formed thereon, and at least the Fe and N on the side surface of the vane are formed. The compound layer containing the main component may be removed.

The material of the roller that is in sliding contact with the vane is formed of an iron-based material having a longitudinal elastic modulus of 9.81 × 10 ^{4 to} 1.47 × 10 ⁵ N / mm ² .

The kinematic viscosity of the base oil is 30 to 120 mm ² / s at 40 ° C.

  The rotary compressor according to claim 1 of the present invention can reduce Hertzian stress while ensuring a sliding surface at the sliding contact portion between the vane and the roller even when a natural refrigerant is used, and has a large sliding distance (ev). Thus, the stress is dispersed, the temperature at the sliding contact portion between the vane and the roller is lowered, and abnormal wear of the roller and the vane can be prevented.

  The rotary compressor according to claim 1 of the present invention does not perform an expensive coating process on the vane, and can sufficiently wear the outer peripheral surface of the roller and the vane even by an inexpensive nitriding process (NV nitriding, nitrosulphurizing, radical nitriding). There is an effect to reduce, and high reliability.

  The rotary compressor according to claim 2 of the present invention can improve the wear resistance of the vane.

  The present invention will be described in detail below.

  FIG. 6 uses polyalkylene glycol or polyalpha-olefin as a lubricating base oil, and compresses carbon dioxide, which is a natural refrigerant, that is, carbon dioxide, which does not contain chlorine molecules in molecules such as evaporated HFC refrigerant. An example of a refrigerating circuit in which the rotary compressor a of the present invention, a condenser b for condensing the refrigerant, an expansion device c for reducing the pressure of the refrigerant, an evaporator d for evaporating the liquefied refrigerant, etc. are sequentially connected by a refrigerant pipe. Indicates.

  FIG. 5 is a cross-sectional explanatory view showing the relationship between the rollers and the vanes of the rotary compressor of the present invention.

  In FIG. 5, the eccentricity (cm) between the rotation center (O1) of the rotating shaft 25 and the roller center (O2) of the roller 38 is E, and the center (O3) of the curvature radius (Rv) of the vane 40 and the roller center (O2). ) Is a line (L2) connecting the center (O3) and the rotation center (O1) of the rotary shaft 25 to α, and the straight line (L1) intersects the outer peripheral surface 38A of the roller 38. When the sliding distance between the point and the point where the straight line (L2) intersects the outer peripheral surface 38A of the roller 38 is ev, ev is calculated by the above equation (4).

The curvature radius (Rv) of the vane 40 at the sliding contact portion with the roller 38, the thickness (T) of the vane 40, the outer peripheral curvature radius (Rr) of the roller 38 slidingly contacting the vane 40, the amount of eccentricity (E), Specifically, when the longitudinal elastic modulus of the roller 38 is E1, E2, the Poisson's ratio of the vane 40 and the roller 38 is respectively set as ν1, ν2, and the design pressure ΔP,
ρ is calculated by the equation (5), the vane pressing force Fv is calculated by the equation (6), the elastic contact surface length d is calculated by the equation (7), and the Hertz stress Pmax is calculated by the equation (9).

  For example, T, Rr, E1, E2, ν1, ν2, and ΔP are set for a two-cylinder rotary compressor having a cylinder inner diameter of 39 mm × height of 14 mm, an eccentricity (E) of 2.88 mm, and an excluded volume of 4.6 cc × 2. Ρ, Fv, d, ev, (T-ev-d) when Rv is changed to 3.2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 16.6 mm (same as Rr) with the values shown in Table 1. ) / 2, Pmax and other calculation results are shown in Table 1.

From Table 1, the Hertzian stress Pmax decreases with increasing Rv, assuming that T = Rv is 100%, while ev (sliding distance) increases, and when Rv = 10 mm, the Hertzian stress Pmax is 66%. Thus, ev is about 2.3 times. However, when Rv = 16.6 mm = Rr, the Hertz stress Pmax is 57%, but (T−ev−d) /2≈0.16 and the sliding contact surface at the sliding contact portion between the vane and the roller. It can be seen that it is difficult to ensure the above.

  From the above results, when Rv is in the range of T <Rv <Rr represented by the above formula (1), Hertzian stress can be reduced while ensuring a sliding surface at the sliding contact portion between the vane and the roller, It can be seen that the sliding distance (ev) is increased, the stress is dispersed, the temperature at the sliding contact portion between the vane and the roller is lowered, and abnormal wear of the roller and the vane can be prevented. A highly reliable rotary compressor that does not perform expensive coating treatment on the vane, and has an effect of sufficiently reducing the wear of the outer peripheral surface of the roller and the vane even by inexpensive nitriding treatment (NV nitriding, nitrosulphurizing, radical nitriding) Can provide.

  When T is in the range of T> 2 · Rv · E / (Rv + Rr) expressed by the above formula (2), the sliding contact surface at the sliding contact portion of the vane with the roller can be secured safely.

  When T is in the range of T> [2 · Rv · E / (Rv + Rr)] + d expressed by the above formula (8), the sliding at the sliding contact portion of the vane with the roller is possible even during high load operation. The contact surface can be secured safely.

The vane is formed of a ferrous material having a longitudinal elastic modulus of 1.96 × 10 ^{5 to} 2.45 × 10 ⁵ N / mm ² , but if the elastic modulus is too small, the wear resistance of the vane is insufficient. Deformation cannot be expected, stress reduction cannot be achieved, and wear resistance cannot be obtained.

  The surface of the vane is treated by nitriding treatment that forms only a diffusion layer mainly composed of Fe and N, or a compound layer mainly composed of Fe and N is formed on the outermost surface of the vane, and Fe And a nitriding treatment in which a diffusion layer mainly composed of N is formed, or a compound layer mainly composed of Fe and S is formed on the outermost surface of the vane, and diffusion mainly composed of Fe—N is formed thereunder. JP-A-10-141269, JP-A-11-217665, JP-A-5-73918 disclose that vanes treated by nitriding to form a layer are effective in wear resistance of the vanes. And the like. However, the wear resistance is not sufficient under HFC refrigerant.

  Therefore, in the present invention, the curvature radius (Rv) of the vane in the sliding portion between the vane and the roller is calculated by the above formulas (1) to (8), and has such a curvature radius (Rv). Higher wear resistance can be obtained by using the vane having the shape in combination with the above treatment.

  Further, a compound layer mainly composed of Fe and N is formed on the outermost surface of the vane, and a diffusion layer mainly composed of Fe and N is formed thereunder, so that at least Fe and N on the side surface of the vane are formed. Nitriding treatment in which a compound layer mainly composed of the main component is removed, a compound layer mainly composed of Fe and S is formed on the outermost surface of the vane, and a diffusion layer mainly composed of Fe-N is formed thereunder, The one in which the compound layer mainly composed of Fe and S on the side surface of the vane is removed corresponds to the dimensional change caused by the change in the crystal structure due to the treatment. Even if removed, high wear resistance can be obtained.

The material of the roller that is in sliding contact with the vane is formed of an iron-based material having a longitudinal elastic modulus of 9.81 × 10 ^{4 to} 1.47 × 10 ⁵ N / mm ² , but if the longitudinal elastic modulus is too small, the wear resistance of the roller is reduced. If it is insufficient and too large, elastic deformation cannot be expected, the stress between the vane and the roller cannot be reduced, and the wear resistance cannot be obtained.

In the present invention, the kinematic viscosity of a base oil made of polyalkylene glycol, polyalphaolefin, or mineral oil used in a rotary compressor using carbon dioxide as a refrigerant is not particularly limited. However, the kinematic viscosity of the base oil is preferably 30 to 120 mm ² / s at 40 ° C. If the kinematic viscosity of the base oil is less than 30 mm ² / s, there is a possibility that abrasion at the sliding contact portion cannot be prevented, and if it exceeds 120 mm ² / s, there is a possibility that it becomes uneconomical such as an increase in power consumption.

  The present invention is not limited to the above-described embodiments, and the refrigerant does not contain a chlorine group, for example, HFC refrigerants such as R32, R125 and R134a, or hydrocarbon refrigerants such as propane and butane, Alternative refrigerants such as natural refrigerants such as carbon dioxide and ammonia may be used, and various modifications may be made without departing from the scope of the claims.

It is explanatory drawing which shows the cross-section of the 2 cylinder type rotary compressor to which this invention is applied. FIG. 2 is a cross-sectional explanatory view showing the relationship among cylinders, rollers, vanes, etc. of the rotary compressor shown in FIG. 1. It is explanatory drawing of the vane of the rotary compressor shown in FIG. FIG. 2 is an explanatory cross-sectional view showing a relationship between rollers and vanes of the rotary compressor shown in FIG. 1. FIG. 2 is a cross-sectional explanatory view showing the relationship between the rotation center of the rotary shaft of the rotary compressor shown in FIG. 1, the center of the roller and the center of curvature radius of the vane. It is explanatory drawing which shows the refrigerating circuit of the rotary compressor shown in FIG.

Explanation of symbols

a rotary compressor b condenser c expansion device d evaporator 1 rotary compressors 31 and 32 cylinder 23 suction port 35 discharge port 26 crank part 38 roller 40 vane

Claims (2)

In rotary compressors using natural refrigerants,
A cylinder having a suction port and a discharge port, a rotary shaft having a crank portion disposed on the axis of the cylinder, a roller disposed between the crank portion and the cylinder and rotating eccentrically, and a groove provided in the cylinder And a compound layer mainly composed of Fe and S is formed on the outermost surface of the vane by nitriding, and a diffusion mainly composed of Fe-N is formed thereunder. A rotary compressor characterized by being treated by a nitriding treatment for forming a layer. By nitriding, a compound layer mainly composed of Fe and S is formed on the outermost surface of the vane, and a diffusing layer mainly composed of Fe—N is formed thereunder, and Fe and S on at least the side surface of the vane are performed. The rotary compressor according to claim 1, wherein the compound layer mainly composed of is removed.