JP7666538B2 - Vane, compressor with vane, and method for manufacturing vane - Google Patents

Description

The present invention relates to a vane, a compressor equipped with the vane, and a method for manufacturing the vane.

The compression section of a rotary compressor includes a cylinder, a piston that revolves along the inner circumferential surface of the cylinder, and a pair of end plates that close both ends of the cylinder. A cylinder chamber is formed between the inner circumferential surface of the cylinder, the outer circumferential surface of the piston, and the pair of end plates. A vane that divides the cylinder chamber into a suction chamber and a compression chamber is disposed in a vane groove formed in the cylinder. The outer circumferential surface of this type of vane has a tip surface that slides against the outer circumferential surface of the piston, a side surface that slides against the inner surface of the vane groove, and an end surface that slides against the end plate. Therefore, the sliding surfaces of the vane (tip surface, side surface, end surface) are required to have wear resistance that makes them resistant to wear even when they repeatedly slide against the piston and end plate, and seizure resistance that makes them resistant to deterioration even when the temperature of the vane itself rises due to frictional heat caused by sliding. In particular, the tip surface of the vane is subjected to a large pressure from the outer circumferential surface of the piston when sliding against the piston, so it is required to have a high hardness (wear resistance) that can withstand this pressure.

JP 2013-155749 A Japanese Unexamined Patent Publication No. 60-26195 Japanese Patent Application Publication No. 11-280648

In the manufacturing process of the vane mounted on the rotary compressor described in Patent Document 1, first, a nitriding process is performed on the outer surface of the vane formed from high-speed steel as the base material, thereby changing the composition of the entire surface of the base material forming the vane into a nitrided diffusion layer. Note that since high-speed steel itself is a steel material with a low Cr content (for example, a Cr content of about 3.8 [wt%] to 4.5 [wt%]), simply nitriding the surface of the base material forming the vane does not provide sufficient wear resistance and seizure resistance required for the sliding surface of the vane. Therefore, in the manufacturing process of the vane described in Patent Document 1, a DLC (diamond-like carbon) layer is further formed as a high-hardness coating layer on the entire surface of the base material with the nitrided diffusion layer exposed on the outer surface, thereby ensuring the wear resistance and seizure resistance required for the sliding surface of the vane. However, when forming a high-hardness coating layer over the entire surface of the base material that forms the vane as described in Patent Document 1, in order to ensure that the particles that form the high-hardness coating layer are in close contact with the entire surface of the vane, the coating process is carried out with multiple vanes arranged at a distance from each other in a film-forming device for the high-hardness coating layer. This reduces the number of vanes that can be coated at one time, which increases the manufacturing costs of the vanes.

On the other hand, a prior art is also known that discloses a vane formed from a steel material with a high Cr content as a base material (Patent Document 2). In the rotary compressor described in Patent Document 2, a nitrided diffusion layer is formed by nitriding the entire surface of a vane formed from a steel material with a high Cr content as a base material, and this nitrided diffusion layer with a high Cr content is used as the sliding surface of the vane to ensure wear resistance and seizure resistance. However, the vane described in Patent Document 2 has sufficient wear resistance and seizure resistance required for the side and end surfaces of the sliding surface of the vane, but the hardness required for the tip surface of the vane, which receives a large force from the piston and receives a large surface pressure because the contact area during sliding with the piston is small, is insufficient, and wear of the tip surface may progress. In addition, in such a vane, by nitriding a steel material with a high Cr content, a hard and brittle nitride compound layer, a so-called white layer, is formed thickly on the nitrided diffusion layer formed on the surface of the base material that forms the vane. For this reason, even if an attempt is made to form a high-hardness coating layer on top of the nitride compound layer to further increase the hardness of the vane, there is a risk that the high-hardness coating layer will peel off along with the nitride compound layer, resulting in a problem of low adhesion of the high-hardness coating layer.

Patent Document 3 describes a technique for improving adhesion between a vane having a nitride compound layer formed on its surface by nitriding and a high-hardness coating layer. In the rotary compressor described in Patent Document 3, after nitriding the surface of the base material forming the vane, the nitrided surface of the base material is irradiated with ions of the constituent molecules of the high-hardness coating layer before forming the high-hardness coating layer. As a result, a mixed layer is formed on the surface of the base material forming the vane, in which the constituent molecules of the high-hardness coating layer and the constituent molecules of the base material of the vane are bonded. Then, by forming a high-hardness coating layer on the mixed layer, the adhesion between the base material having the nitride compound layer formed thereon and the high-hardness coating layer can be improved. However, adding a special process for forming a mixed layer as in Patent Document 3 increases the manufacturing cost of the vane.

The disclosed technology has been developed in consideration of the above, and aims to provide a vane, a compressor equipped with the vane, and a method for manufacturing the vane that reduces the manufacturing costs of the vane while preventing the hard coating from peeling off from the base material that forms the tip surface of the vane.

One aspect of the vane disclosed in the present application is a vane used in a compressor including a cylinder, a piston that revolves along the inner circumferential surface of the cylinder, and an end plate that closes an end of the cylinder, and divides a cylinder chamber surrounded by the cylinder, the piston, and the end plate into a suction chamber and a compression chamber. The vane has a base material formed from a material having a chromium content of more than 4.5 wt %, and a hard coating covering a tip surface of the base material, wherein a base layer and a nitriding layer are formed on the base material, the hard coating is formed from a single material on the surface of the nitriding layer of the base material and is exposed on the outer surface of the tip surface , the base material further has a side surface that slides against the cylinder and an end surface that slides against the end plate, and the side surface and the end surface of the base material have a nitriding layer exposed on the outer surfaces of the side surface and the end surface, respectively.

According to one aspect of the vane disclosed in this application, it is possible to reduce the manufacturing costs of the vane while preventing the hard coating from peeling off from the base material that forms the tip surface of the vane.

FIG. 1 is a vertical cross-sectional view showing a compressor equipped with a vane according to a first embodiment. FIG. 2 is an exploded perspective view showing a compression portion of the compressor of the first embodiment. FIG. 3 is a perspective view showing the vane of the first embodiment. FIG. 4 is a cross-sectional view showing the hard coating and the nitride layer of the vane of the first embodiment. FIG. 5 is an enlarged cross-sectional view showing the tip of the vane of the first embodiment. FIG. 6 is a schematic diagram for explaining a manufacturing method of the vane of the first embodiment. FIG. 7 is a cross-sectional view showing the surface of the base material immediately after the nitriding treatment. FIG. 8 is a schematic diagram for explaining an example of a hard coating forming process in Example 1. FIG. 9 is an enlarged cross-sectional view showing a tip portion of the vane according to the second embodiment. FIG. 10 is a schematic diagram for explaining an example of a hard coating forming process in Example 2.

Below, the vane, compressor equipped with the vane, and manufacturing method of the vane according to the embodiment disclosed in the present application will be described with reference to the drawings. Note that the following description does not limit the technology of the present disclosure. In addition, in the following description, the same components are given the same reference numerals, and duplicate descriptions will be omitted.

(Compressor configuration)
Fig. 1 is a vertical cross-sectional view showing a compressor equipped with a vane of Example 1. As shown in Fig. 1, the compressor 1 is a rotary compressor that accommodates a compression section 12 that draws in a refrigerant from an accumulator 25 and compresses the refrigerant and discharges the compressed refrigerant into the main container 10, and a motor 11 that drives the compression section 12, inside a main container 10, and discharges the high-pressure refrigerant compressed by the compression section 12 into the main container 10 and further into a refrigeration cycle through a discharge pipe 107. The compressor 1 also includes a rotating shaft 15 that transmits the driving force of the motor 11 to the compression section 12, and an accumulator 25 fixed to the outer circumferential surface of the main container 10.

The main container 10 is provided with an upper compression section suction pipe 102T and a lower compression section suction pipe 102S penetrating the main container 10 for sucking low-pressure refrigerant of the refrigeration cycle into the compression section 12. In detail, the upper guide pipe 101T is fixed to the main container 10, for example, by brazing, and the upper compression section suction pipe 102T passes through the inside of the upper guide pipe 101T and is fixed to the upper guide pipe 101T, for example, by brazing. Similarly, the lower guide pipe 101S is fixed to the main container 10, for example, by brazing, and the lower compression section suction pipe 102S passes through the inside of the lower guide pipe 101S and is fixed to the lower guide pipe 101S, for example, by brazing.

A discharge pipe 107 for discharging the high-pressure refrigerant compressed in the compression section 12 from inside the main container 10 to the refrigeration cycle is provided through the upper part of the main container 10. A base member 310 that supports the entire compressor 1 is fixed to the lower part of the main container 10 by welding.

The accumulator 25 includes an accumulator suction pipe 27 that draws refrigerant from the refrigeration cycle into the accumulator 25, and an upper gas-liquid separation pipe 31T and a lower gas-liquid separation pipe 31S for sending the gas refrigerant to the compression section 12. The accumulator suction pipe 27 is connected to the upper part of the accumulator 25. The upper gas-liquid separation pipe 31T is connected to the upper compression section suction pipe 102T via the upper connecting pipe 104T. The lower gas-liquid separation pipe 31S is connected to the lower compression section suction pipe 102S via the lower connecting pipe 104S.

2 is an exploded perspective view showing the compression section 12 of the compressor 1 of the first embodiment. As shown in FIGS. 1 and 2, the compression section 12 has an upper cylinder 121T, a lower cylinder 121S, an intermediate partition plate 140, an upper end plate 160T, and a lower end plate 160S. The upper end plate 160T, the upper cylinder 121T, the intermediate partition plate 140, the lower cylinder 121S, and the lower end plate 160S are stacked in this order and fixed by a plurality of bolts 175. The upper end plate 160T is provided with a main bearing portion 161T. The lower end plate 160S is provided with a sub-bearing portion 161S. The rotating shaft 15 is provided with a main shaft portion 153, an upper eccentric portion 152T, a lower eccentric portion 152S, and a sub-shaft portion 151. The rotating shaft 15 has a main shaft portion 153 and a sub-shaft portion 151 supported by the compression section 12. The main shaft portion 153 of the rotating shaft 15 is fitted into the main bearing portion 161T of the upper end plate 160T, and the sub-shaft portion 151 of the rotating shaft 15 is fitted into the sub-bearing portion 161S of the lower end plate 160S, so that the rotating shaft 15 is rotatably supported by the main bearing portion 161T and the sub-bearing portion 161S.

The motor 11 has a stator 111 arranged on the outside and a rotor 112 arranged on the inside. The stator 111 is fixed to the inner circumferential surface 10a of the main container 10 by, for example, shrink fitting or welding. The rotor 112 is fixed to the rotating shaft 15 by shrink fitting.

The inside of the main container 10 is filled with lubricating oil 18 in an amount that almost completely immerses the compression section 12, in order to lubricate the sliding members of the compression section 12 and to seal the high-pressure and low-pressure sections in the cylinder chamber.

Next, the compression section 12 will be described in detail with reference to Figure 2. The upper cylinder 121T has a cylindrical upper hollow section 130T therein, and an upper piston 125T is disposed in the upper hollow section 130T. The upper piston 125T is fitted into the upper eccentric section 152T of the rotating shaft 15. The lower cylinder 121S has a cylindrical lower hollow section 130S therein, and a lower piston 125S is disposed in the lower hollow section 130S. The lower piston 125S is fitted into the lower eccentric section 152S of the rotating shaft 15.

The upper cylinder 121T is provided with an upper vane groove 128T extending from the upper hollow portion 130T to the outer periphery, and an upper vane 127T is disposed in the upper vane groove 128T. The upper cylinder 121T is provided with an upper spring hole 124T leading from the outer periphery to the upper vane groove 128T, and an upper spring 126T is disposed in the upper spring hole 124T. The lower cylinder 121S is provided with a lower vane groove 128S extending from the lower hollow portion 130S to the outer periphery, and a lower vane 127S is disposed in the lower vane groove 128S. The lower cylinder 121S is provided with a lower spring hole 124S leading from the outer periphery to the lower vane groove 128S, and a lower spring 126S is disposed in the lower spring hole 124S.

When one end of the upper vane 127T is pressed against the upper piston 125T by the upper spring 126T, the space outside the upper piston 125T in the upper hollow portion 130T of the upper cylinder 121T is divided into the upper suction chamber 131T and the upper compression chamber 133T, which are upper cylinder chambers. The upper cylinder 121T has an upper suction hole 135T that communicates with the upper suction chamber 131T from the outer periphery. The upper suction hole 135T is connected to the upper compression section suction pipe 102T. When one end of the lower vane 127S is pressed against the lower piston 125S by the lower spring 126S, the space outside the lower piston 125S in the lower hollow portion 130S of the lower cylinder 121S is divided into the lower suction chamber 131S and the lower compression chamber 133S, which are lower cylinder chambers. The lower cylinder 121S has a lower suction hole 135S that communicates with the lower suction chamber 131S from the outer periphery. The lower compression section suction pipe 102S is connected to the lower suction hole 135S.

The upper end plate 160T is provided with an upper discharge hole 190T that penetrates the upper end plate 160T and communicates with the upper compression chamber 133T. The upper end plate 160T is fixed with an upper rivet 202T to the upper end plate 160T, which is an upper discharge valve 200T that is a reed valve that opens and closes the upper discharge hole 190T, and an upper discharge valve holder 201T that regulates the warping of the upper discharge valve 200T. An upper end plate cover 170T that covers the upper discharge hole 190T is arranged on the upper side of the upper end plate 160T, and an upper end plate cover chamber 180T that is closed by the upper end plate 160T and the upper end plate cover 170T is formed. The upper end plate cover 170T is fixed to the upper end plate 160T by a plurality of bolts 175 that fix the upper end plate 160T and the upper cylinder 121T. The upper end plate cover 170T is provided with an upper end plate cover discharge hole 172T that communicates between the upper end plate cover chamber 180T and the inside of the main container 10. When the compression section 12 is provided in the main container 10, the inner peripheral surface 10a of the main container 10 is shrink-fitted to the outer peripheral surface 182a of the upper end plate 160T and is joined to the main container 10 by a plurality of welded parts. The structure of the upper end plate 160T in this embodiment 1 will be described in detail later.

The lower end plate 160S is provided with a lower discharge hole 190S that penetrates the lower end plate 160S and communicates with the lower compression chamber 133S. The lower end plate 160S is fixed with a lower rivet 202S to a lower discharge valve 200S, which is a reed valve that opens and closes the lower discharge hole 190S, and a lower discharge valve holder 201S that regulates the warping of the lower discharge valve 200S. A lower end plate cover 170S that covers the lower discharge hole 190S is arranged below the lower end plate 160S, forming a lower end plate cover chamber 180S that is closed by the lower end plate 160S and the lower end plate cover 170S (see Figure 1). The lower end plate cover 170S is fixed to the lower end plate 160S by a plurality of bolts 175 that fix the lower end plate 160S and the lower cylinder 121S.

In addition, the compression section 12 is provided with a refrigerant passage hole 136 (see FIG. 2) that penetrates the lower end plate 160S, the lower cylinder 121S, the intermediate partition plate 140, the upper end plate 160T, and the upper cylinder 121T and connects the lower end plate cover chamber 180S and the upper end plate cover chamber 180T.

The flow of refrigerant caused by the rotation of the rotating shaft 15 will be described below. The rotation of the rotating shaft 15 causes the upper piston 125T fitted in the upper eccentric portion 152T of the rotating shaft 15 and the lower piston 125S fitted in the lower eccentric portion 152S to revolve, so that the upper suction chamber 131T and the lower suction chamber 131S expand in volume and draw in refrigerant. As a refrigerant intake path, the low-pressure refrigerant of the refrigeration cycle is sucked into the inside of the accumulator 25 through the accumulator suction pipe 27, and only the gaseous refrigerant is sucked into the upper gas-liquid separation pipe 31T and the lower gas-liquid separation pipe 31S. The gaseous refrigerant sucked into the upper gas-liquid separation pipe 31T is sucked into the upper suction chamber 131T through the upper connecting pipe 104T and the upper compression section suction pipe 102T. Similarly, the gas refrigerant drawn into the lower gas-liquid separation pipe 31S passes through the lower connecting pipe 104S and the lower compression section suction pipe 102S and is drawn into the lower suction chamber 131S.

Next, the flow of the discharged refrigerant caused by the rotation of the rotating shaft 15 will be explained. As the rotating shaft 15 rotates, the upper piston 125T fitted to the upper eccentric part 152T of the rotating shaft 15 revolves, compressing the refrigerant while reducing the volume of the upper compression chamber 133T. When the pressure of the compressed refrigerant becomes higher than the pressure in the upper end plate cover chamber 180T outside the upper discharge valve 200T, the upper discharge valve 200T opens and discharges the refrigerant from the upper compression chamber 133T to the upper end plate cover chamber 180T. The refrigerant discharged into the upper end plate cover chamber 180T is discharged into the main container 10 from the upper end plate cover discharge hole 172T provided in the upper end plate cover 170T.

In addition, as the rotating shaft 15 rotates, the lower piston 125S fitted in the lower eccentric portion 152S of the rotating shaft 15 revolves, compressing the refrigerant while reducing the volume of the lower compression chamber 133S. When the pressure of the compressed refrigerant becomes higher than the pressure in the lower end plate cover chamber 180S outside the lower discharge valve 200S, the lower discharge valve 200S opens and discharges the refrigerant from the lower compression chamber 133S to the lower end plate cover chamber 180S. The refrigerant discharged to the lower end plate cover chamber 180S passes through the refrigerant passage hole 136 and the upper end plate cover chamber 180T and is discharged into the main body container 10 from the upper end plate cover discharge hole 172T provided in the upper end plate cover 170T.

The refrigerant discharged into the main container 10 is guided to the top of the motor 11 through a notch (not shown) on the outer periphery of the stator 111 that connects the top and bottom, or through a gap in the winding part of the stator 111 (not shown), or through a gap 115 (see Figure 1) between the stator 111 and the rotor 112, and is discharged from a discharge pipe 107 located at the top of the main container 10.

Next, the flow of the lubricating oil 18 will be explained. The lubricating oil 18 sealed in the lower part of the main container 10 is supplied to the compression section 12 through the inside of the rotating shaft 15 (not shown) by the centrifugal force of the rotating shaft 15. The lubricating oil 18 supplied to the compression section 12 is entrained in the refrigerant and is discharged into the inside of the main container 10 together with the refrigerant in a mist form. The mist of the lubricating oil 18 discharged into the inside of the main container 10 is separated from the refrigerant by the centrifugal force of the rotational force of the motor 11, and returns to the bottom of the main container 10 as oil droplets. However, some of the lubricating oil 18 is not separated and is discharged into the refrigerant together with the refrigerant into the refrigeration cycle. The lubricating oil 18 discharged into the refrigeration cycle circulates through the refrigeration cycle and returns to the accumulator 25, where it is separated inside the accumulator 25 and accumulates in the lower part of the accumulator 25. The lubricating oil 18 accumulated in the lower part of the accumulator 25 is sucked into the upper suction chamber 131T and the lower suction chamber 131S together with the suctioned refrigerant.

(Characteristic configuration of compressor 1)
Next, the characteristic configuration of the vane of the first embodiment will be described. FIG. 3 is a perspective view showing the vane of the first embodiment. The upper vane 127T and the lower vane 127S (hereinafter also referred to as vane 127) have the same structure, so the upper vane 127T will be described below, and the description of the lower vane 127S will be omitted. The upper vane 127T has a tip surface 129a that slides against the outer circumferential surface of the upper piston 125T, and a first side surface 129b and a second side surface 129c that slide against the inner surface of the upper vane groove 128T. The upper vane 127T also has a first end surface 129d that slides against the end surface of the upper end plate 160T, a second end surface 129e that slides against the end surface of the intermediate partition plate 140 as an end plate, and a back surface 129f that is pressed by the upper spring 126T. In addition, to supplement the description of the lower vane 127S, the lower vane 127S has a first end face 129d that slides against an end face of the intermediate partition plate 140 serving as an end plate, and a second end face 129e that slides against an end face of the lower end plate 160S. The first side face 129b and the second side face 129c, and the first end face 129d and the second end face 129e are each formed in a flat plate shape.

The tip surface 129a of the upper vane 127T is formed in an arc shape when viewed from a direction perpendicular to the first end surface 129d and the second end surface 129e. The back surface 129f of the upper vane 127T has an engagement portion 138 with which the end of the upper spring 126T engages, which is formed by cutting out a part of the flat back surface 129f.

The upper vane 127T includes a base material 210 and a hard coating 220. The base material 210 has a base layer 211 (described later) formed of a material with a chromium (Cr) content of more than 4.5 [wt%]. Examples of materials include SUS440C (a type of martensitic stainless steel) with a chromium (Cr) content of about 16 [wt%] to 18 [wt%], SKD61 (a type of die steel) with a chromium (Cr) content of about 4.8 [wt%] to 5.5 [wt%], and SKD11 (a type of die steel) with a chromium (Cr) content of about 11.0 [wt%] to 13.0 [wt%]. In this way, the upper vane 127T has an appropriate wear resistance and seizure resistance because the base material layer 211 of the base material 210 is formed of a material with a chromium (Cr) content of more than 4.5 [wt%]. Furthermore, when the base material layer 211 of the base material 210 of the upper vane 127T is made of stainless steel with a chromium (Cr) content exceeding 10 wt%, the wear resistance and seizure resistance of the first side surface 129b and the second side surface 129c, which have a particularly large sliding area, can be sufficiently ensured.

Figure 4 is a cross-sectional view showing the hard coating 220 of the vane 127 of Example 1. Figure 4 shows a cross-section perpendicular to the first end face 129d and the second end face 129e of the vane 127. Figure 5 is a cross-sectional view showing an enlarged tip portion of the vane 127 of Example 1. Figure 5 shows a cross-section perpendicular to the first side face 129b and the second side face 129c of the vane 127.

As shown in FIG. 4, a hard coating 220 is formed on the tip surface 129a of the upper vane 127T. In addition, a nitride diffusion layer 212 is formed on the entire outer peripheral surface of the base material 210 so as to cover the base material layer 211, and a dense layer 213 is formed on the nitride diffusion layer 212.

As shown in Fig. 5, a hard coating 220 is formed on the entire tip surface 129a of the upper vane 127T. The hard coating 220 is formed on the surface side of the dense layer 213 of the base material 210 and is in close contact with the dense layer 213. The hard coating 220 is formed of a material having a Vickers hardness of 1500 HV or more. Examples of the hard coating 220 include diamond-like carbon (DLC), chromium nitride (CrN), and dichromium nitride (Cr ₂ N). Since the hard coating 220 is provided on the tip surface 129a of the upper vane 127T, the wear resistance of the tip surface 129a is appropriately ensured.

(Method of manufacturing vane)
The manufacturing method of the vane of Example 1 is a method for manufacturing the vane 127 of Example 1 configured as described above. Figure 6 is a schematic diagram for explaining the manufacturing method of the vane of Example 1. Figure 6 shows that the properties of the vane 127 change in the order of Figure 6(a) to Figure 6(d) by the manufacturing method of the vane of Example 1.

As shown in FIG. 6(a), the entire base material 210 of the vane 127 before nitriding is made of a material with a chromium (Cr) content of more than 4.5 wt%. In the embodiment, the region of the base material 210 that has the same composition as the base material 210 before nitriding is called the base material layer 211. The high chromium (Cr) content in the base material layer 211 of the base material 210 ensures the vane 127's wear resistance and seizure resistance. In the vane 127 of the embodiment 1, for example, the base material layer 211 of the base material 210 is made of martensitic stainless steel with a chromium (Cr) content of about 16 wt% to 18 wt%. The vane 127 has a base material layer 211 of the base material 210 formed from stainless steel with a chromium (Cr) content of more than 10 wt %, which ensures sufficient wear resistance and seizure resistance, especially on the first side surface 129b and the second side surface 129c, which have a large sliding area.

After the base material 210 is formed, it is quenched (a heat treatment in which the metal is heated until it becomes an austenitic structure, and then rapidly cooled to obtain a martensite structure). This quenching improves the wear resistance and mechanical strength of the base material 210. After quenching the base material 210, it is tempered (a heat treatment that stabilizes the metal structure by holding the metal, whose structure has become unstable due to quenching, etc., at an appropriate temperature). This tempering improves the toughness of the base material 210.

After the base material 210 is tempered, the base material 210 is subjected to a nitriding process (step S1). Examples of nitriding processes include gas nitriding, gas soft nitriding, and ion nitriding. As shown in FIG. 6(b), in the nitriding process, nitrogen atoms N penetrate and diffuse from the surface of the base material 210 to the inside, forming a nitride layer 214 on the surface of the base material 210. Therefore, the nitride layer 214 is formed so as to surround the base material layer 211. The nitride layer 214 here refers to a layer formed by changing the structure of the base material layer 211 by the nitriding process. Note that the part of the base material 210 that is formed with the same composition as the base material layer 211 of the base material 210 at the stage immediately before the nitriding process is referred to as the base material layer 211 even after the nitriding process.

FIG. 7 is an enlarged cross-sectional view showing the surface of the base material 210 immediately after the nitriding treatment. In the embodiment, the nitride layer 214 is formed of a nitride diffusion layer 212 and a nitride compound layer 216 (white layer). The nitride diffusion layer 212 is formed on the outer surface side of the base material layer 211. The nitride diffusion layer 212 is formed of an α (alpha) phase having a body-centered cubic structure, and nitrogen atoms N are solid-dissolved in the nitride diffusion layer 212. The nitride compound layer 216 (white layer) is formed of a dense layer 213 and a porous layer 217. The dense layer 213 is formed on the outer surface side of the nitride diffusion layer 212. The dense layer 213 is mainly composed of iron nitride Fe ₄ N and is formed of a γ′ (gamma prime) phase having a face-centered cubic structure. The porous layer 217 is formed on the outer surface side of the dense layer 213 and is formed so as to be exposed to the outer surface of the base material 210 immediately after the nitriding treatment. The porous layer 217 is composed mainly of iron nitrides Fe ₂ N and Fe ₃ N, and is formed from an ε (epsilon) phase having a close-packed hexagonal crystal structure. Therefore, on the surface of the base material 210 immediately after the nitriding process, the porous layer 217, the dense layer 213, the nitrided diffusion layer 212, and the base layer 211 are arranged in this order from the outside.

After the base material 210 is nitrided, the surface of the base material 210 is scraped (step S2). In this process, the surface layers of the nitride compound layer 216 formed on the tip surface 129a, the first side surface 129b, the second side surface 129c, the first end surface 129d, and the second end surface 129e are scraped. As a result, the surface layer having minute bulges and minute recesses generated on the surface of the base material 210 due to the nitriding process is scraped, and the first side surface 129b, the second side surface 129c, the first end surface 129d, and the second end surface 129e are flattened, thereby ensuring the dimensional accuracy and surface accuracy (flatness) of the vane 127 sliding against the inner surface of the upper vane groove 128T (lower vane groove 128S), the upper end plate 160T (lower end plate 160S), and the end surface of the intermediate partition plate 140. In Example 1, at least the porous layer 217 of the nitride layer 216 (white layer) is removed so that the dense layer 213 is exposed on the surface of the base material 210.

After the surface of the base material 210 is scraped, a hard coating 220 is formed on the tip end surface 129a of the base material 210 (step S3). The hard coating 220 is made of a material having a Vickers hardness of 1500 HV or more. Examples of the material include diamond-like carbon (DLC), chromium nitride (CrN), and dichromium nitride (Cr ₂ N). This improves the wear resistance of the tip end surface 129a of the vane 127. In the first embodiment, the hard coating 220 is formed so as to adhere closely to the dense layer 213 of the tip end surface 129a.

The hard film 220 is formed, for example, by vacuum deposition and sputtering in a processing chamber provided in the film forming apparatus. FIG. 8 is a schematic diagram for explaining an example of the formation process of the hard film 220 in Example 1. In the formation process (step S3) of the hard film 220, a plurality of base materials 210 are arranged in a processing chamber provided in the film forming apparatus. At this time, the plurality of base materials 210 are arranged so that the side surfaces 129b, 129c of the base materials 210 placed side by side are in contact with each other, i.e., the opposing first side surface 129b and the second side surface 129c, and the end surfaces 129d, 129e of the base materials 210 placed side by side are in contact with each other, i.e., the opposing first end surface 129d and the second end surface 129e. The film forming apparatus forms the hard film 220 on each tip surface 129a of the plurality of base materials 210 arranged in this manner at once. This allows the number of base materials 210 on which the hard coating 220 is formed to be increased in one formation process, thereby reducing the manufacturing cost of the vane 127.

Furthermore, by arranging the side surfaces 129b, 129c and end surfaces 129d, 129e of adjacent base materials 210 so that they are in contact with each other, the side surfaces 129b, 129c and end surfaces 129d, 129e can be masked so that the hard coating 220 is not formed on the side surfaces 129b, 129c and end surfaces 129d, 129e. In this way, by using other vanes 127 as masking members for coating the vanes 127, it is not necessary to provide a separate process for masking the surfaces of the base material 210 on which the hard coating 220 is not formed, and the masking process can be reduced. The vane manufacturing method can reduce the manufacturing cost of the vanes 127 by eliminating the masking process.

The adhesion of the hard coating 220 to the dense layer 213 is better than that of the hard coating 220 to the porous layer 217. Therefore, the vane 127 of Example 1, which is manufactured so that the hard coating 220 is adhered to the dense layer 213, can adhere the hard coating 220 to the base material 210 more strongly than other vanes in which the hard coating 220 and the base material 210 are adhered to each other via the porous layer 217, and can prevent the hard coating 220 from peeling off from the tip surface 127a.

The porous layer 217 has the characteristics of being hard but brittle. Therefore, the vane 127 of Example 1, in which the dense layer 213 is exposed on the surface of the base material 210 by removing the porous layer 217 and then the hard film 220 is formed so as to adhere to the dense layer 213, can prevent abnormal wear caused by the porous layer falling off when sliding at high surface pressure compared to other vanes in which the hard film 220 and the base material 210 are adhered to each other via the porous layer 217.

(Effect of the vane 127 of the first embodiment)
The vane 127 of Example 1 is used in a compressor 1 that has an upper cylinder 121T (lower cylinder 121S), an upper piston 125T (lower piston 125S) that revolves along the inner surface of the upper cylinder 121T (lower cylinder 121S), and an upper end plate 160T (lower end plate 160S, intermediate partition plate 140) that closes the end of the upper cylinder 121T (lower cylinder 121S), and divides the upper cylinder chamber (lower cylinder chamber) surrounded by the upper cylinder 121T (lower cylinder 121S), the upper piston 125T (lower piston 125S), and the upper end plate 160T (lower end plate 160S, intermediate partition plate 140) into an upper suction chamber 131T (lower suction chamber 131S) and an upper compression chamber 133T (lower compression chamber 133S). The vane 127 has a base material 210 formed from a material with a chromium (Cr) content exceeding 4.5 wt %, and a hard coating 220 covering a tip end surface 129a of the base material 210. The base material 210 has a base material layer 211 and a nitride diffusion layer 212, or the base material layer 211, the nitride diffusion layer 212, and a dense layer 213 made of a gamma prime phase containing Fe4N as a main component formed on the nitride diffusion layer 212. The hard coating 220 is formed on the surface of either the nitride diffusion layer 212 of the base material 210 or the dense layer 213 of the base material 210. As a result, the vane 127 ensures the hardness of the tip surface 129a, which requires particularly high wear resistance, by the hard coating 220, while also ensuring the wear resistance and seizure resistance of the sliding surfaces (other than the tip surface 129a) on which the hard coating 220 is not formed, and can prevent the hard coating 220 from peeling off from the tip surface 129a.

The base material 210 of the vane 127 of the first embodiment further includes a first side surface 129b and a second side surface 129c that slide against the upper cylinder 121T (lower cylinder 121S), and a first end surface 129d (second end surface 129e) that slides against the upper end plate 160T (lower end plate 160S, intermediate partition plate 140). The first side surface 129b and the second side surface 129c of the base material 210 and the first end surface 129d (second end surface 129e) are exposed on the outer surface of either a nitride diffusion layer 212, a dense layer 213 made of a gamma prime phase mainly composed of iron nitride Fe ₄ N, or a porous layer 217 mainly composed of iron nitride Fe ₂ N and Fe ₃ N. As a result, vane 127 can ensure sufficient wear resistance and seizure resistance for the sliding surfaces other than tip surface 129a (first side surface 129b, second side surface 129c, first end surface 129d, and second end surface 129e).

The hard coating 220 of the vane 127 in Example 1 has a Vickers hardness of 1500 HV or more. This allows the vane 127 to ensure adequate wear resistance of the tip surface 129a. For example, the hard coating 220 is made of diamond-like carbon (DLC). This allows the vane 127 to ensure particularly adequate wear resistance of the tip surface 129a.

The base material 210 of the vane 127 of the first embodiment is formed of stainless steel with a chromium (Cr) content of 10.5 wt. % or more. For example, the base material 210 is formed of martensitic stainless steel with a chromium (Cr) content of about 16 wt. % to 18 wt. %. In this way, the vane 127 can ensure sufficient wear resistance and seizure resistance, especially for the first side surface 129b, the second side surface 129c, the first end surface 129d, and the second end surface 129e, which have a large sliding area, because the base material layer 211 of the base material 210 has a high chromium (Cr) content.

The manufacturing method of the vane of Example 1 is a manufacturing method used when manufacturing the vane 127 of Example 1, and includes a process (step S1) of nitriding a base material 210 to form a nitride layer 214 (including a nitride diffusion layer 212, a dense layer 213, and a porous layer 217 mainly composed of iron nitrides Fe ₂ N and Fe ₃ N) on the base material 210 by changing the structure of the base material layer 211 by the nitriding process, a process (step S2) of removing at least the porous layer 217 of the nitride layer 214 on the tip surface 129 a after the nitride layer 214 is formed on the base material 210 to expose the dense layer 213 of the nitride layer 214, and a process (step S3) of forming a hard coating 220 on the surface of the dense layer 213 on the tip surface 129 a after the dense layer 213 is exposed. According to this method of manufacturing the vane, the hard coating 220 can be strongly adhered to the dense layer 213 of the tip surface 129a of the base material 210, thereby preventing the hard coating 220 from peeling off from the base material 210 that forms the tip surface 129a of the vane 127.

In addition, the base material 210 further includes a first side surface 129b and a second side surface 129c that slide against the upper cylinder 121T (lower cylinder 121S), and a first end surface 129d (second end surface 129e) that slides against the upper end plate 160T (lower end plate 160S, intermediate partition plate 140). In the manufacturing method of the vane of Example 1, in the process (step S3) of forming the hard coating 220 on the base material 210, the multiple base materials 210 are arranged so that the first side surfaces 129b and the second side surfaces 129c or the first end surfaces 129d (second end surfaces 129e) of adjacent base materials 210 are in contact with each other, and the hard coating 220 is formed on each tip surface 129a of the multiple base materials 210 at once. According to such a vane manufacturing method, for example, the number of base materials 210 on which the hard coating 220 is formed in one formation process can be increased, thereby reducing the manufacturing cost of the vane 127. In addition, for example, the manufacturing cost of the vane 127 can be reduced by using other vanes 127 as masking members for coating the vane 127.

As shown in Figures 9 and 10, the vane of Example 2 is the same as the vane 127 of Example 1 described above, except that the dense layer 213 of the vane 127 of Example 1 described above is omitted. Figure 9 is a cross-sectional view showing the vane of Example 2. Figure 10 is a schematic diagram for explaining the manufacturing method of the vane of Example 2. Figure 10 shows that the properties of the vane 127 change in the order of Figures 10(a) to 10(d) due to the manufacturing method of the vane of Example 2.

As shown in FIG. 9, the vane of Example 2 has a hard coating 220 formed over the entire tip surface 129a, similar to the vane 127 of Example 1 described above. The hard coating 220 is formed on the surface of the nitrided diffusion layer 212 of the base material 210 and adheres to the nitrided diffusion layer 212. The vane of Example 2 differs from the vane of Example 1 in that the hard coating 220 adheres to the nitrided diffusion layer 212 as a result of not only the porous layer 217 but also the dense layer 213 being removed in the process of scraping the surface of the base material 210 described below.

The manufacturing method of the vane of Example 2 is a method for manufacturing the vane 127 of Example 2, and as shown in FIG. 10, step S1 of the manufacturing method of the vane of Example 2 is similar to step S1 of the manufacturing method of the vane of Example 1 described above. On the other hand, in the manufacturing method of the vane of Example 2, the process of step S2 of the manufacturing method of the vane of Example 1 described above is replaced with another process, step S4. Also, in the manufacturing method of the vane of Example 2, the process of step S3 of the manufacturing method of the vane of Example 1 is replaced with another process, step S5. In the manufacturing method of the vane of Example 2, after the base material 210 is nitrided in step S1, the surface of the base material 210 is scraped, and the dense layer 213 and the porous layer 217 are removed so that the nitride diffusion layer 212 is exposed on the surface of the base material 210 (step S4). After the surface of the base material 210 is scraped in step S4, a hard film 220 is formed on the nitriding layer 212 of the tip surface 129a of the base material 210 (step S5). According to this vane manufacturing method, the vane 127 of Example 2 is appropriately manufactured so that the hard film 220 is formed on the surface of the nitriding layer 212 of the base material 210 and adheres closely to the nitriding layer 212.

The adhesion of the hard coating 220 to the nitride diffusion layer 212 is roughly equivalent to the adhesion of the hard coating 220 to the dense layer 213, and is better than the adhesion of the hard coating 220 to the porous layer 217. Therefore, like the vane 127 of the first embodiment described above, the vane of the second embodiment can more strongly adhere the hard coating 220 to the tip surface 129 of the base material 210, and can prevent the hard coating 220 from peeling off from the tip surface 127a, compared to other vanes in which the hard coating 220 and the base material 210 are in contact with each other via the porous layer 217.

The vane of Example 2 is formed so that the nitride diffusion layer 212 is exposed on the outer surface of the base material 210 at the first side surface 129b, the second side surface 129c, the first end surface 129d, and the second end surface 129e. The nitride diffusion layer 212, like the dense layer 213, has better wear resistance and seizure resistance than the base material layer 211. Therefore, the vane of Example 2 can ensure sufficient wear resistance and seizure resistance, like the vane 127 of Example 1 described above, even at sliding points (side surfaces and end surfaces) where the hard coating 220 is not formed.

In addition, in the vane of Example 2, the entire nitride compound layer 216 (dense layer 213, porous layer 217), which is a white layer formed by nitriding, is removed. Therefore, compared to the case in Example 1 in which the dense layer 213 is exposed on the outer surface of the vane 127, the possibility of the dense layer 213 falling off from the surface of the nitride diffusion layer 212 can be eliminated.

In contrast, the vane of the described Example 1 is easier to process than the vane of Example 2 because it is only necessary to remove the porous layer 217 (for example, removing the surface layer of the white layer by about several μm) of the nitride compound layer 216 (dense layer 213, porous layer 217), which is a white layer formed by nitriding.

In the vane manufacturing method of the second embodiment described above, the entire surface of the base material 210 is scraped off so that both the dense layer 213 and the porous layer 217 are removed in step S4, but the surface of the base material 210 may be scraped off so that the dense layer 213 remains on a surface (side or end surface) other than the tip surface 129a. In the vane manufactured by this vane manufacturing method, as in the vane of the embodiment described above, the hard film 220 is in close contact with the nitride diffusion layer 212, and the hard film 220 can be prevented from peeling off from the tip surface 129a while ensuring the wear resistance and seizure resistance of the surface on which the hard film 220 is not formed.

In the vane manufacturing method of the embodiment described above, the entire surface of the base material 210 is scraped off so that the porous layer 217 is removed in step S2 or step S4, but the porous layer 217 may be scraped off so that the porous layer 217 remains on a surface (side surface or end surface) other than the tip surface 129a. In the vane manufactured by such a vane manufacturing method, as in the vane of the embodiment described above, the hard coating 220 is in close contact with the dense layer 213 or the nitride diffusion layer 212, and the hard coating 220 can be prevented from peeling off from the tip surface 129a while ensuring the wear resistance and seizure resistance of the surface on which the hard coating 220 is not formed.

In the vane manufacturing method of the embodiment described above, the hard coating 220 is formed on the tip surfaces 129a of the multiple base materials 210 with the side surfaces and end surfaces in close contact with each other, but the hard coating 220 may be formed on the tip surfaces 129a of the multiple base materials 210 with the side surfaces and end surfaces not in close contact with each other. In this case, the surfaces (side surfaces and end surfaces) of the multiple base materials 210 different from the tip surfaces 129a may be masked so that the hard coating 220 is not formed.

In the above-described embodiment, a two-cylinder rotary compressor having two cylinders 121, an upper cylinder 121T and a lower cylinder 121S, was used as an example of the compressor 1, but a one-cylinder rotary compressor having only one cylinder 121 may also be used.

Although the embodiments have been described above, the embodiments are not limited to the above. The above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the spirit of the embodiments.

1 Compressor 121T Upper cylinder (cylinder)
121S Lower Cylinder (Cylinder)
125T upper piston (piston)
125S Lower piston (piston)
127 Vane 127T Upper Vane (Vane)
127S Lower vane (vane)
129a Tip surface 129b First side surface 129c Second side surface 129d First end surface 129e Second end surface 160T Upper end plate (end plate)
160S Lower end plate (end plate)
210 Base material 211 Base material layer 212 Nitrided diffusion layer 213 Dense layer 214 Nitrided layer 216 Nitrided compound layer (white layer)
217 Porous layer 220 Hard coating

Claims (9)

A cylinder;
A piston that revolves along an inner circumferential surface of the cylinder;
an end plate that closes an end of the cylinder;
The compressor is used in a compressor having
a vane that divides a cylinder chamber surrounded by the cylinder, the piston, and the end plate into a suction chamber and a compression chamber,
A base material formed from a material having a chromium content of more than 4.5 wt %;
A hard coating covering a tip surface of the base material,
A base layer and a nitride diffusion layer are formed on the base material,
the hard coating is formed of a single material on the surface of the nitride diffusion layer of the base material , and is exposed on an outer surface of the tip end face ;
The base material further includes a side surface that slides against the cylinder and an end surface that slides against the end plate,
The side surface and the end surface of the base material have a nitride diffusion layer exposed on the outer surface of each of the side surface and the end surface.
A vane comprising: The vane according to claim 1 , wherein the hard coating has a Vickers hardness of 1500 HV or more. The vane of claim 2 , wherein the hard coating is formed from diamond-like carbon. 2. The vane of claim 1, wherein the base material is formed from stainless steel having a chromium content of 10.5 wt. % or more. The vane of claim 4 , wherein the base material is formed from a martensitic stainless steel. A vane according to any one of claims 1 to 5;
The cylinder;
The piston;
The end plate;
A compressor comprising: A cylinder;
A piston that revolves along an inner circumferential surface of the cylinder;
an end plate that closes an end of the cylinder;
The compressor is used in a compressor having
A method for manufacturing a vane that divides a cylinder chamber surrounded by the cylinder, the piston, and the end plate into a suction chamber and a compression chamber,
The vane is
A base material formed from a material having a chromium content of more than 4.5 wt %;
A hard coating covering a tip surface of the base material,
A base layer and a nitride diffusion layer are formed on the base material,
The method for manufacturing the vane includes the steps of:
a step of subjecting the base layer of the base material to a nitriding treatment to form a nitride layer on the base material, the nitride layer including the nitride diffusion layer, a dense layer made of a gamma prime phase containing Fe ₄ N as a main component, and a porous layer containing Fe ₂ N and Fe ₃ N as main components;
a step of removing the porous layer and the dense layer of the nitride layer after the nitride layer is formed on the base material to expose the nitride diffusion layer of the nitride layer;
and after exposing the nitriding diffusion layer, forming the hard coating made of a single material on the surface of the nitriding diffusion layer of the tip end face to expose the hard coating on the outer surface of the tip end face .
A method for manufacturing a vane. The tip end surface of the base material is formed into a curved shape such that the center of the width direction of the vane protrudes toward the piston,
In the step of forming the hard coating, the hard coating is formed in the curved area of the tip surface of the base material.
A method for manufacturing the vane according to claim 7. The base material further includes a side surface that slides against the cylinder and an end surface that slides against the end plate,
8. The method for manufacturing a vane according to claim 7, wherein in the step of forming the hard coating on the base material, a plurality of the base materials are arranged so that the side surfaces or the end faces of adjacent base materials are in contact with each other, and a hard coating is formed on each tip surface of the plurality of the base materials at once.

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