Sliding material and gas compression machine

Abstract

To provide a sliding material excellent in abrasion resistance.SOLUTION: A sliding material 12 includes: resin 12a; a first particle 12b arranged in the resin 12a and constituted by an inorganic material; and a second particle 12c arranged in the resin 12a and constituted by an inorganic material having Vickers hardness larger than that of the first particle 12b. When a value obtained by dividing the Vickers hardness of the second particle 12c by the Vickers hardness of the first particle 12b is defined as a hardness ratio and a value obtained by dividing a content of the first particle 12b with respect to the resin 12a by a content of the second particle 12c with respect to the resin 12a is defined as a content ratio, a value obtained by dividing the hardness ratio by the content ratio is 0.3 or more and 2.8 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sliding member and a gas compression machine.

Background Art

[0002] As gas compression machines for compressing gases such as air, reciprocating gas compression machines and scroll gas compression machines are known. For example, in a reciprocating gas compression machine, a piston ring is attached as a sliding member that slides on the inner surface of a cylinder to a piston that reciprocates inside a metal cylinder. Further, for example, in a scroll gas compression machine, a tip seal is attached as a sliding member to the end of a metal fixed scroll or a orbiting scroll that contacts and slides while orbiting with respect to the fixed scroll.

[0003] As the sliding member, a resin material typified by, for example, polytetrafluoroethylene (PTFE) is used. For example, since PTFE has high crystallinity and low shear strength, when it is subjected to shear, it easily exfoliates at the micro level and adheres to the mating surface (sliding surface) such as the inner surface of the cylinder. In order to improve the wear durability of a sliding member made of PTFE as a base material, a composite resin material containing metal particles is known.

[0004] The abstract of Patent Document 1 describes that "a resin sliding member for a machine tool mainly composed of a PTFE resin that slidably contacts a metal mating member under oil lubrication is blended with metal powder having a standard electrode potential lower than that of the base metal of the metal mating member and excluding copper alloys of the copper-aluminum system. Alternatively, recycled PTFE resin powder is further blended with this resin sliding member."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The inventors investigated the matter and found that the sliding material described in Patent Document 1 has problems in terms of wear resistance, although the details will be described later with reference to examples. The problem that this disclosure aims to solve is to provide sliding materials and gas compressors with excellent wear resistance. [Means for solving the problem]

[0007] The sliding material of this disclosure includes a resin, first particles disposed in the resin and made of an inorganic material, and second particles disposed in the resin and made of an inorganic material having a greater Vickers hardness than the first particles, wherein the hardness ratio is defined as the value obtained by dividing the Vickers hardness of the second particles by the Vickers hardness of the first particles, and the content ratio is defined as the value obtained by dividing the content of the second particles in the resin by the content of the first particles in the resin, and the value obtained by dividing the hardness ratio by the content ratio is 0.3 or more and 2.8 or less. Other solutions will be described later in the embodiments for carrying out the invention. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide sliding materials and gas compressors with excellent wear resistance. [Brief explanation of the drawing]

[0009] [Figure 1] This is an enlarged cross-sectional view showing the sliding portion of a gas compressor according to one embodiment. [Figure 2] This is a cross-sectional view showing the structure of a gas compressor according to one embodiment. [Figure 3] Figure 2 shows a magnified view of parts of the fixed scroll and orbiting scroll of the gas compressor shown in Figure 2. [Figure 4] This is a cross-sectional view showing the structure of a gas compressor machine in another embodiment. [Figure 5] This is a magnified view of the inside of the cylinder shown in Figure 4. [Figure 6] This is a diagram illustrating the testing method for friction testing. [Figure 7] This is a diagram illustrating the results of a friction test. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments (referred to as "models") for implementing this disclosure will be described with reference to the drawings. Within the description of one embodiment below, other embodiments applicable to that embodiment will also be described as appropriate. This disclosure is not limited to the following embodiments, and different embodiments can be combined or modified as appropriate without significantly impairing the effects of this disclosure. In addition, the same reference numerals will be used for the same components, and redundant descriptions will be omitted. Furthermore, components having the same function will be given the same name. The illustrations are for illustrative purposes only, and for illustrative purposes, the actual configuration may be changed or some components may be omitted or modified between drawings without significantly impairing the effects of this disclosure.

[0011] Figure 1 is an enlarged cross-sectional view showing the sliding part 10 in a gas compressor 20, 40 of one embodiment. Both parts in Figure 1 correspond to part A in Figure 3 and part B in Figure 5, which will be described later. As will be described in detail later, the gas compressor 20 is, for example, a scroll type, and the gas compressor 40 is, for example, a reciprocating type. First, the sliding part 10 provided in the gas compressors 20, 40 will be described with reference to Figure 1.

[0012] The sliding part 10 comprises a metal (e.g., aluminum) member 11 and a sliding material 12. From the perspective of member 11, the sliding material 12 slides against member 11 when it moves, for example, by pivoting or reciprocating. From the perspective of sliding material 12, member 11 slides against sliding material 12 when it moves, for example, by pivoting or reciprocating. The sliding material 12 is provided in, for example, a fixed scroll 21 and a pivoting scroll 22 (both in Figure 3), and a piston 42 (Figure 5), although details will be described later.

[0013] In the sliding part 10, the sliding material 12 slides in contact with the member 11 on the sliding surface 13. Lubricating oil, grease, etc. may be present on the sliding surface 13. However, in the gas compressors 20 and 40, the sliding material 12 slides on the sliding surface 13 in an oil-free manner. In such cases, the effects of this disclosure can be particularly greatly enhanced. Here, "oil-free" means a state in which no lubricating oil, etc., is present at all. However, a so-called oil-less state in which sufficient lubricating oil, etc., is not present is also acceptable.

[0014] The component 11 comprises a metal material 11a and a surface layer 11b. The metal material 11a functions, for example, as a base material, and the surface layer 11b is formed on the surface of the metal material 11a. A sliding surface 13 is formed on the surface of the surface layer 11b, and the sliding material 12 slides while in contact with the surface layer 11b.

[0015] The metal material 11a is not particularly limited as long as it is a metal that has sufficient strength to be used as a component of the gas compressors 20, 40. For example, in addition to light metals such as aluminum, magnesium, and silicon, elements or compounds (alloys, etc.) of transition metals such as iron, chromium, nickel, molybdenum, titanium, and copper can be used. More specifically, for example, aluminum-based materials such as aluminum and aluminum alloys, iron-based materials such as iron and iron-nickel alloys, titanium-based materials such as titanium and titanium alloys, and copper-based materials such as copper and copper alloys can be used. Among these, aluminum-based materials are preferred, as they provide excellent wear resistance. Aluminum-based materials may contain, for example, small amounts of magnesium, silicon, etc. Iron-based materials may contain, for example, chromium, nickel, molybdenum, etc.

[0016] The surface layer 11b may be, for example, a naturally occurring oxide film formed on the metal material 11a, or an artificially applied surface coating. In the case of a naturally occurring oxide film, for example, when the metal material 11a is made of an aluminum-based material, the surface layer 11b is made of aluminum oxide. Also, when the metal material 11a is made of an iron-based material, the surface layer 11b is made of iron oxide. When the metal material 11a is made of a copper-based material, the surface layer 11b is made of copper oxide.

[0017] In the illustrated example, the surface layer 11b is an anodic oxidation layer made of aluminum oxide, and the sliding surface 13 is the surface of the anodic oxidation layer. By making the sliding surface 13 like this, the metal material 11a can be protected.

[0018] When the surface layer 11b is a surface coating, as an example, the surface layer 11b can be formed by plating, physical vapor deposition (PVD) method, chemical vapor deposition (CVD) method, carburizing treatment, etc. In this case, the surface layer 11b is usually composed of a material containing at least one of, for example, aluminum, phosphorus, chromium, iron, nickel, and zinc. Examples of surface coatings containing such elements include anodic oxidation treatment, aluminum plating, nickel plating, chromium plating, iron plating, zinc plating, etc.

[0019] In the example shown in FIG. 1, the surface layer 11b is formed on the surface of the metal material 11a. However, the surface layer 11b does not necessarily have to be formed on the metal material 11a, and the metal material 11a may be exposed on the surface of the member 11. That is, the metal surface of the member 11 may be formed of the metal constituting the metal material 11a, or may be formed of the surface layer 11b formed on the metal material 11a.

[0020] The sliding member 12 includes a resin 12a, a first particle 12b, and a second particle 12c. The resin 12a functions as a base material, for example. The resin 12a is preferably a fluororesin. By using a fluororesin, the durability can be improved. Also, the transfer of the fluororesin to the sliding surface 13 can be promoted. As the fluororesin, for example, at least one of the above-mentioned PTFE, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF) can be used. The resin 12a may use two or more different types of resins in combination. For example, PTFE and a fluororesin other than PTFE may be mixed and used in combination. Also, the resin 12a does not have to be a fluororesin, and any other resin may be used.

[0021] The first particles 12b are disposed in the resin 12a and are composed of an inorganic material. Preferably, the first particles 12b are dispersed in the resin 12a. Preferably, the first particles 12b are composed of a metal. By composing them of a metal, it is easier to set the Vickers hardness of the first particles 12b to a desired value.

[0022] The Vickers hardness (HV) of the first particle 12b is preferably that of a ductile soft material, specifically, for example, 50 HV or more, with an upper limit of, for example, 200 HV or less, and preferably 100 HV or less. Having a Vickers hardness within this range allows the first particle 12b to exhibit ductility when sliding on the sliding surface 13, thereby improving wear resistance.

[0023] The first particle 12b is preferably at least one of copper, a copper-based alloy, aluminum, or an aluminum-based alloy. Using these can improve wear resistance. Note that a copper-based alloy and an aluminum-based alloy mean that copper or aluminum is the most abundant metal in the alloy, respectively.

[0024] It is preferable to form a chemical conversion treatment layer between the resin 12a and the first particle 12b. By forming a chemical conversion treatment layer, various functions can be imparted due to the chemical conversion treatment layer. The chemical conversion treatment layer is formed, for example, on the surface of the first particle 12b. The chemical conversion treatment layer is, for example, an adhesion layer that improves the bonding strength between the resin 12a and the first particle 12b. The adhesion layer can be formed, for example, by coupling treatment, plating treatment, etc. Coupling treatment can be performed using, for example, a titanium-based or silicon-based coupling agent. Plating treatment can be performed using a transition metal with high chemical affinity to the resin 12a, such as nickel plating or iron plating.

[0025] The average particle size (size) of the first particle 12b is not particularly limited, but can be, for example, 10 μm or more, preferably 50 μm or more, with an upper limit of, for example, 500 μm or less, preferably 100 μm or less. The average particle size of the first particle 12b can be measured, for example, using a laser diffraction particle size distribution analyzer. d

[0026] The second particle 12c is disposed in the resin 12a and is composed of an inorganic material. Preferably, the second particle 12c is dispersed in the resin 12a. Preferably, the second particle 12c is composed of at least one of metal or ceramic. This makes it easier to set the Vickers hardness of the second particle 12c to a desired value in relation to the first particle 12b.

[0027] The second particle 12c is composed of an inorganic material having a higher Vickers hardness than the first particle 12b. Examples of such inorganic particles include hard metal particles such as diatomaceous earth, alumina, silica, titanium oxide, zinc oxide, and silicon carbide, as well as ceramic particles. In particular, the second particle 12c is preferably at least one of diatomaceous earth, alumina, silica, titanium oxide, zinc oxide, or silicon carbide. Using these materials makes it easier to achieve a higher Vickers hardness than the first particle 12b.

[0028] The average particle size (size) of the second particle 12c is not particularly limited, but can be, for example, 10 μm or more, preferably 20 μm or more, with an upper limit of, for example, 500 μm or less, preferably 100 μm or less. The average particle size of the second particle 12c can be measured, for example, using a laser diffraction particle size distribution analyzer.

[0029] When the content ratio (hereinafter referred to as the "content ratio of this disclosure") is defined as the value obtained by dividing the content of the first particle 12b relative to the resin 12a by the content of the second particle 12c relative to the resin 12a, the content ratio of this disclosure is not particularly limited. The content ratio of this disclosure is preferably 3 or more, more preferably 6 or more, with an upper limit preferably 40 or less, and more preferably 20 or less. The content ratio of this disclosure can be calculated by {content of the first particle 12b (mass%)} / {content of the second particle 12c (mass%)}.

[0030] When the hardness ratio (hereinafter referred to as the hardness ratio of this disclosure) is defined as the value obtained by dividing the Vickers hardness of the second particle 12c by the Vickers hardness of the first particle 12b, the hardness ratio of this disclosure is not particularly limited. The hardness ratio of this disclosure is preferably 6 or more, more preferably 10 or more, with an upper limit preferably 30 or less, and more preferably 25 or less. The hardness ratio of this disclosure can be calculated by {Vickers hardness (HV) of the second particle 12c} / {Vickers hardness (HV) of the first particle 12b}. Furthermore, by using Vickers hardness as an index of hardness, the hardness of the first particle 12b and the second particle 12c can be appropriately expressed, and the material selection for the first particle 12b and the second particle 12c can be appropriately performed based on the ratio of this disclosure, which will be described in detail later.

[0031] In the sliding material 12 of this disclosure, the value obtained by dividing the hardness ratio of this disclosure by the content ratio of this disclosure (hereinafter referred to as the value of this disclosure) is 0.3 or more and 2.8 or less. Therefore, it is preferable to adjust the hardness ratio of this disclosure and the content ratio of this disclosure so that the content ratio of this disclosure is within this range. By setting the value of this disclosure within this range, excellent wear resistance can be achieved, as will be described in detail later with reference to the examples. The value of this disclosure is preferably 1.1 or more, preferably 1.8 or less as the upper limit, and more preferably 1.6 or less. By setting the value of this disclosure within this range, particularly excellent wear resistance can be achieved. The value of this disclosure can be calculated by {hardness ratio of this disclosure (-) / (content ratio of this disclosure (-)}.

[0032] The reasons for setting the values ​​of this disclosure within the above range are as follows. The inventors conducted numerous friction tests according to the test method shown in Figure 7 below, for example. As a result, the inventors found a correlation between the amount of wear of the sliding material 12 and the hardness ratio and content ratio of the first particle 12b and the second particle 12c of this disclosure. Specifically, they identified that if the hardness ratio of the disclosure is too high or the content ratio of the disclosure is too low, the amount of wear increases due to the abrasive action of the first particle 12b and the second particle 12c. On the other hand, they clarified that if the hardness ratio of the disclosure is too low or the content ratio of the disclosure is too high, the durability of the sliding material 12 itself decreases and the amount of wear increases.

[0033] On the other hand, if the hardness ratio and content ratio of the first particles 12b and second particles 12c are controlled within an appropriate range, the relatively harder second particles 12c primarily effectively support the shear stress during sliding. In addition, the relatively softer first particles 12b support the shear stress, and their wear particles partially adhere to the member 11, thereby reducing the aggressiveness from the harder member 11. These synergistic effects are realized when the values ​​of the disclosure, with the hardness ratio and content ratio of the disclosure as one parameter, are appropriately controlled. Therefore, the values ​​of the disclosure contribute, for example, to improving the wear resistance of the sliding material 12 in harsh environments.

[0034] The sliding material 12 may further contain fibers. The fibers are arranged in the resin 12a, preferably dispersed in the resin 12a. Including fibers can improve the mechanical strength of the sliding material 12. Examples of fibers include at least one of carbon fibers, glass fibers, metal fibers, and ceramic fibers. Among these, carbon fibers are preferred. Using carbon fibers allows for both weight reduction and improved strength of the sliding material 12.

[0035] The length and diameter of the fibers are not particularly limited as long as they do not significantly impair the effects of this disclosure, but for example, the length may be, for example, 10 μm to 300 μm, and the diameter may be, for example, 1 μm to 30 μm. The length and diameter may be determined by actual measurements taken from a cross-sectional micrograph of the sliding material 12.

[0036] The sliding material 12 may further contain a solid lubricant. The solid lubricant is preferably in particulate form, for example, having a particle size of 10 μm or more and 500 μm or less. The particle size can be measured, for example, as the average particle size using a laser diffraction particle size distribution analyzer.

[0037] The solid lubricant is disposed in the resin 12a, preferably dispersed within the resin 12a. Examples of solid lubricants include at least one of molybdenum disulfide, graphite, or boron nitride. Among these, molybdenum disulfide is preferred as the solid lubricant. By using molybdenum disulfide, friction can be reduced and wear resistance can be improved, as well as the strength of the sliding material 12 against stresses such as shear stress.

[0038] In the sliding material 12, the types of at least the resin 12a, first particles 12b, and second particles 12c can be confirmed as follows. Specifically, the type of resin 12a, first particles 12b, and second particles 12c can be easily confirmed by chemical analysis such as scanning electron microscopy, energy dispersive X-ray analysis, infrared spectroscopy, and X-ray diffraction of the surface or crushed material of the sliding material 12. Furthermore, the hardness of the first particles 12b and second particles 12c can be confirmed by hardness measurement such as a nanoindenter, and the content of the first particles 12b and second particles 12c can be easily confirmed by thermogravimetric analysis, etc.

[0039] The sliding material 12 can be manufactured, for example, as follows. Specifically, a uniform mixed powder is obtained by mixing resin 12a powder, first particles 12b, and second particles 12c with, for example, powder such as carbon fiber or molybdenum disulfide using a mixer. Next, a molded product is obtained by molding the mixture into an arbitrary shape by compression molding or injection molding. Finally, the sliding material 12 is obtained by firing the molded product in an electric furnace or the like. It is preferable to adjust the temperature range appropriately during firing according to the type of resin 12a etc. used.

[0040] Figure 2 is a cross-sectional view showing the structure of a gas compressor 20 according to one embodiment. In the example shown in Figure 2, the gas compressor 20 is a scroll-type gas compressor. The gas compressor 20 includes a casing 23 that forms the outer shell of the gas compressor 20, a drive shaft 24 rotatably mounted on the casing 23, a fixed scroll 21 attached to the casing 23, and a pivotable scroll 22 pivotally mounted on the crankshaft 24A of the drive shaft 24.

[0041] The fixed scroll 21 has a fixed end plate 21a and a fixed scroll wrap 21b formed in a spiral shape on one main surface side of the fixed end plate 21a. The orbiting scroll 22 has an orbiting end plate 22a and an orbiting scroll wrap 22b formed in a spiral shape on one main surface side of the orbiting end plate 22a. The orbiting scroll 22 has a boss portion 22f protruding from the center of the back side of the orbiting end plate 22a.

[0042] The orbiting scrolls 22 are positioned opposite each other such that the orbiting scroll wrap 22b engages with the fixed scroll wrap 21b. This creates a compression / expansion chamber 25 between the fixed scroll wrap 21b and the orbiting scroll wrap 22b. The compression / expansion chamber 25 is provided in the gas compressor 20 and performs at least one of compression or expansion on a gas. In the illustrated example, the incoming gas is compressed in the compression / expansion chamber 25.

[0043] An intake port 26 is drilled on the outer circumference of the fixed end plate 21a of the fixed scroll 21. The intake port 26 communicates with the outermost compression and expansion chamber 25. In addition, an outlet port 27 is drilled in the center of the fixed end plate 21a of the fixed scroll 21. The outlet port 27 opens into the innermost compression and expansion chamber 25.

[0044] The drive shaft 24 is rotatably supported in the casing 23 via a ball bearing 28. One end of the drive shaft 24 is connected to an electric motor (not shown) or the like outside the casing 23, and the other end of the drive shaft 24 extends into the casing 23 to become a crankshaft 24A. The axis of the crankshaft 24A is eccentric by a predetermined dimension with respect to the axis of the drive shaft 24.

[0045] An annular thrust bearing portion 31 is provided on the inner circumference of the casing 23 on the side facing the orbiting scroll 22. A thrust plate 32 is provided between the thrust bearing portion 31 and the orbiting end plate 22a. The thrust plate 32 is formed as an annular plate from a metal material such as iron. When the orbiting scroll 22 rotates, its surface slides against the orbiting end plate 22a. As a result, the thrust plate 32, together with the thrust bearing portion 31, receives the thrust load (the direction that separates the orbiting scroll 22 from the stationary scroll 21) that acts on the orbiting scroll 22 mainly during compression operation. This suppresses galling and abnormal wear between the casing 23 and the orbiting end plate 22a.

[0046] Furthermore, an Oldham ring 33 is provided between the thrust bearing portion 31 and the slewing end plate 22a, at a position closer to the center than the thrust plate 32. When the slewing scroll 22 is rotationally driven by the drive shaft 24, the Oldham ring 33 suppresses the rotation of the slewing scroll 22 and imparts circular motion with a predetermined radius of rotation by the crankshaft 24A.

[0047] When the drive shaft 24 is rotated by an electric motor (not shown), the orbiting scroll 22 rotates with a predetermined orbital radius, and the outside air drawn in from the intake port 26 is sequentially compressed in the compression and expansion chamber 25. This compressed air is discharged from the discharge port 27 of the fixed scroll 21 to an external air tank or the like.

[0048] Figure 3 is an enlarged view of a portion of the fixed scroll 21 and orbiting scroll 22 of the gas compressor 20 shown in Figure 2. The fixed scroll 21 and orbiting scroll 22 are examples of the components 11 shown in Figure 1. The tip seals 291 and 292 are examples of the sliding material 12 shown in Figure 1. Therefore, the sliding part 10 comprises the fixed scroll 21, the orbiting scroll 22, and the tip seals 291 and 292.

[0049] A groove 21d is formed on the end face 21c of the fixed scroll wrap 21b that faces the slewing end plate 22a, and a tip seal 291 is fitted into this groove 21d. Similarly, a groove 22d is formed on the end face 22c of the slewing scroll wrap 22b that faces the fixed end plate 21a, and a tip seal 292 is fitted into this groove 22d as well.

[0050] The tip seals 291 and 292 slide over the lap bottom surfaces 21e and 22e that partition the compression and expansion chamber 25. The lap bottom surfaces 21e and 22e are examples of the sliding surfaces 13 shown in Figure 1. The fixed scroll 21 and the orbiting scroll 22 are made of aluminum-based materials such as aluminum or aluminum alloy. The surfaces of the fixed scroll 21 and the orbiting scroll 22 are anodized. Therefore, the lap bottom surfaces 21e and 22e are the surfaces of the anodized layer.

[0051] As the orbiting scroll 22 rotates, the tip seal 291 slides against the bottom surface 22e of the orbiting end plate 22a, and the tip seal 292 slides against the bottom surface 21e of the fixed end plate 21a. This suppresses contact between the fixed scroll wrap 21b and the bottom surface 22e of the orbiting end plate 22a, and between the orbiting scroll wrap 22b and the bottom surface 21e of the fixed end plate 21a. As a result, a smooth sliding state can be obtained.

[0052] In the sliding portion between the thrust plate 32 (Figure 2) and the slewing end plate 22a, the surface of the thrust plate 32 or the surface of the slewing end plate 22a that forms these sliding surfaces may be coated with the sliding material 12. Furthermore, although the above description shows an example in which the thrust plate 32 is made of a metal material such as iron, the thrust plate 32 itself may also be made of the sliding material 12.

[0053] Furthermore, the above description illustrates a mechanism that suppresses the rotation of the orbiting scroll 22 using a thrust plate 32 and an Oldham ring 33 positioned closer to the center than the thrust plate 32. However, the scroll-type gas compressor 20 is not limited to this, and this disclosure can also be applied to scroll-type gas compressors using other anti-rotation mechanisms, such as auxiliary cranks and Oldham couplings, which are not shown in the illustrations.

[0054] Figure 4 is a cross-sectional view showing the structure of a gas compressor 40 in another embodiment. In the example shown in Figure 4, the gas compressor 40 is a reciprocating gas compressor. The gas compressor 40 has a cylinder 41 and a piston 42 that reciprocates inside the cylinder 41. A compression-expansion chamber 43 is formed in the space defined by the piston 42 within the cylinder 41. The compression-expansion chamber 43 is an example of a chamber that performs at least one of compression or expansion on a gas. In the illustrated example, the incoming gas is compressed in the compression-expansion chamber 43.

[0055] The upper end of the cylinder 41 is closed by a partition plate 44, and the partition plate 44 is provided with an intake port 44a and an outlet port 44b. The intake port 44a and the outlet port 44b are provided with an intake valve 44c and an outlet valve 44d, respectively, and piping (not shown) is connected to the ends of the intake valve 44c and the outlet valve 44d, respectively.

[0056] The cylinder 41 is open at its lower end and is connected to the housing 45 at this lower end. A connecting rod 46 is connected to the piston 42 via a piston pin 46a. A motor 47 is housed inside the housing 45. The motor 47 is connected to the connecting rod 46 via a pulley 48 and a belt 49 wound between the pulleys 48.

[0057] When the gas compressor 40 is in operation, power from the motor 47 is transmitted to the piston 42 via a belt 49, pulley 48, and connecting rod 46. By moving the piston 42 up and down, outside air is drawn into the compression / expansion chamber 43 from the intake port 44a, and the intake gas is compressed in the compression / expansion chamber 43. The compressed gas is discharged outside the compression / expansion chamber 43 through the discharge port 44b and recovered by piping.

[0058] Figure 5 is a magnified view of the inside of the cylinder 41 shown in Figure 4. The cylinder 41 is an example of the member 11 shown in Figure 1. The piston ring 421 is an example of the sliding material 12 shown in Figure 1. Therefore, the sliding part 10 comprises the cylinder 41 and the piston ring 421. The rider ring 422 may also be formed from the sliding material 12.

[0059] The cylinder 41 may be made of metal or resin. For example, the cylinder 41 may be made of an aluminum-based material such as aluminum or an aluminum alloy. The inner circumferential surface 43a of the cylinder 41 (an example of the sliding surface 13 shown in Figure 1) is anodized. Therefore, the inner circumferential surface 43a is the surface of the anodized layer.

[0060] The piston 42 is fitted with a piston ring 421 and a rider ring 422. As the piston 42 moves up and down, the piston ring 421 and rider ring 422 slide against the inner circumferential surface 43a of the cylinder 41. This suppresses contact and galling between the piston 42 and the cylinder 41. As a result, a smooth sliding state between the piston 42 and the cylinder 41 can be obtained.

[0061] In the gas compressors 20 and 40, the gas supplied to the compression and expansion chambers 25 and 43 may be, for example, atmospheric air, or a dry gas with extremely low water vapor content. The sliding material 12 of this disclosure can exhibit sufficient wear resistance regardless of the type of gas being compressed. For this reason, the gas compressors 20 and 40 to which the sliding material 12 of this disclosure is applied can also be used, for example, to compress a dry gas. Examples of dry gases include gases with a dew point of -30°C or lower. Specifically, examples include synthetic air, high-purity nitrogen gas, oxygen gas, helium gas, argon gas, hydrogen gas, etc. [Examples]

[0062] The present disclosure will be explained in more detail below with reference to examples.

[0063] The sliding materials for Examples 1-7 and Comparative Examples 1-5 were prepared using the materials shown in Table 1 below. For resin 12a, PTFE was used as an example of a fluororesin. The first particle 12b was copper as an example of a metal, with an average particle size of 60 μm. The second particle 12c was diatomaceous earth, silica, or alumina, all examples of ceramics. The average particle size of diatomaceous earth was 36 μm, the average particle size of silica was 24 μm, and the average particle size of alumina was 50 μm.

[0064] [Table 1]

[0065] For each material used, the Vickers hardness of copper is 57 HV, diatomaceous earth is 600 HV, silica is 900 HV, and alumina is 1385 HV. Therefore, diatomaceous earth, silica, and alumina all have a Vickers hardness greater than that of copper. The hardness ratio of this disclosure is 11 when the first particle 12b is copper and the second particle 12c is diatomaceous earth, the hardness ratio of this disclosure is 16 when the first particle 12b is copper and the second particle 12c is silica, and the hardness ratio of this disclosure is 24 when the first particle 12b is copper and the second particle 12c is alumina.

[0066] In Examples 1-7 and Comparative Examples 1-4, copper is used as the first particle 12b. In Comparative Example 5, the first particle 12b is not used. In Examples 1-3, 5, 7 and Comparative Examples 2, 4, diatomaceous earth is used as the second particle 12c. In Example 4 and Comparative Examples 3, 5, silica is used as the second particle 12c. In Example 6, alumina is used as the second particle 12c. In Comparative Example 1, the second particle 12c is not used, and Comparative Example 1 corresponds to the technology described in Patent Document 1 above.

[0067] In Examples 1-7, the values ​​of the disclosed material are between 0.3 and 2.8. In Comparative Examples 1-5, the values ​​of the disclosed material are either less than 0.3 or greater than 2.8. In Comparative Example 5, the content ratio of the disclosed material is 0, and the denominator when the value of the disclosed material is expressed as a fraction is 0. Therefore, the value of the disclosed material cannot be uniquely conceivable and becomes infinite. However, even in this case, the value of the disclosed material is at least greater than 2.8.

[0068] Figure 6 illustrates the friction test method. The sliding materials of Examples 1-7 and Comparative Examples 1-5 were processed into block-shaped test pieces 71, and a ring-shaped test piece 72 was brought into contact with the upper surface of the test piece 71. The test piece 71 has a roughly rectangular prism shape with a width of 6 mm, a length of 20 mm, and a height of 5 mm. On the test piece 71, a chamfer of 0.5 mm in depth was made at two opposing corners at the top of the prism. The test piece 72 is made of aluminum alloy and its surface is treated with sulfuric acid anodizing. The test piece 72 has a cylindrical shape with an inner diameter of 9 mm and an outer diameter of 13 mm.

[0069] A friction test was performed by rotating test piece 72 while test piece 71 was fixed. The experimental conditions for the friction test were controlled to a contact pressure of 1 MPa, a speed of 2 m / s, and a temperature of 120°C, and the two pieces were slid for 15 hours.

[0070] Figure 7 illustrates the results of the friction test. The vertical axis of the graph in Figure 7 shows the amount of wear on the test specimen 71 after the friction test. The amount of wear was determined by dividing the mass loss before and after the friction test by the density of the test specimen 71. Furthermore, to make the results easier to understand, the amount of wear is expressed as a relative value with Comparative Example 1 set to 100.

[0071] In Examples 1 to 7, where the value of this disclosure was between 0.3 and 2.8, the amount of wear was all below 100, which corresponds to the value of the technology described in Patent Document 1. In particular, the amount of wear was especially low when the value of this disclosure was between 1.1 and 1.8 (Examples 2 to 5). On the other hand, in Comparative Examples 1 to 5, where the value of this disclosure was less than 0.3 or greater than 2.8, the amount of wear was 100 or more. In particular, in Comparative Example 5, the amount of wear was 1600, which was 16 times that of Comparative Example 1.

[0072] These results demonstrate that by using first particles 12b and second particles 12c, which have different Vickers hardnesses, in combination, and by setting the value of this disclosure to between 0.3 and 2.8, the amount of wear can be reduced and the wear resistance can be improved. In particular, by using first particles 12b and second particles 12c in combination, and by setting the value of this disclosure to between 0.3 and 2.8, the amount of wear can be reduced compared to when each is used individually (Comparative Examples 1 and 5).

[0073] On the other hand, in Comparative Examples 1 and 2, where the values ​​in this disclosure are less than 0.3, it is thought that the first particle 12b and the second particle 12c easily yielded due to external shear stress. For this reason, the durability of the material itself is low, and the amount of wear is thought to have increased compared to Examples 1 to 7.

[0074] In the technology described in Patent Document 1, which corresponds to Comparative Example 1, PTFE is used as the base material and a copper alloy is added. Since copper and copper alloys are soft, in harsh environments such as high pressure, they cannot support shear stress and easily yield, leading to increased wear. The copper alloy is classified as the first particle 12b in this disclosure, and the material corresponding to the second particle 12c is not used. For this reason, in the sliding material described in Patent Document 1, the hardness ratio of this disclosure is small and the content ratio of this disclosure is large. That is, because the value of this disclosure is small, it is thought that in harsh environments the durability of the material itself is insufficient and the amount of wear increases.

[0075] Furthermore, in Comparative Examples 3 to 5, where the value of this disclosure exceeded 2.8, wear increased due to abrasive action. In particular, in Comparative Example 5, which did not contain the first particle 12b, it is thought that the abrasive action was strong due to the silica having an extremely high Vickers hardness, resulting in an extremely large amount of wear.

[0076] In Comparative Example 5, the relatively soft first particle 12b is not used as described above, and the second particle 12c, which is composed of relatively hard silica, is used. Hard materials such as silica and alumina generate abrasive particles due to shearing and other factors as described above. As a result, the amount of wear due to cutting action tends to increase. Therefore, in a sliding material that does not use the first particle 12b and uses only the second particle 12c, the hardness ratio of the disclosed material is large and the content ratio of the disclosed material is small. That is, because the value of the disclosed material is large, it is thought that the amount of wear increased due to abrasive action.

[0077] As described above, the sliding material 12 of this disclosure can improve wear resistance (friction durability). Therefore, by applying the sliding material 12 to, for example, tip seals 291, 292 (Figure 3), piston rings 421 (Figure 5), etc., the replacement life of these can be extended. As a result, the maintenance cycle and lifespan of gas compressors 20, 40 can be extended. [Explanation of symbols]

[0078] 10 Sliding part 12 Sliding material 12a Resin 12b 1st particle 12c 2nd particle 13 Sliding surface 20 Gas Compressor Machine 21 Fixed scroll (sliding part) 21e Wrap bottom surface (sliding surface) 22e Wrap bottom surface (sliding surface) 22. Swivel scroll (sliding part) 25 Compression and expansion chamber (chamber) 291 Tip seal (sliding material, sliding part) 292 Tip seal (sliding material, sliding part) 40 Gas Compressor 41 Cylinder (sliding part) 421 Piston ring (sliding material, sliding part) 43 Compression and expansion chamber (chamber) 43a Inner surface (sliding surface)

Claims

1. Resin and First particles arranged in the resin and made of an inorganic material; second particles arranged in the resin and made of an inorganic material having a Vickers hardness greater than that of the first particles; When a value obtained by dividing the Vickers hardness of the second particles by the Vickers hardness of the first particles is defined as a hardness ratio, and a value obtained by dividing the content of the first particles relative to the resin by the content of the second particles relative to the resin is defined as a content ratio, The value obtained by dividing the hardness ratio by the content ratio is 0.3 or more and 2.8 or less, The second particles are at least one of alumina, silica, zinc oxide, and silicon carbide. A sliding material characterized by:

2. the first particles are made of a metal; The second particles are made of at least one of a metal and a ceramic.

2. The sliding material according to claim 1 .

3. The Vickers hardness of the first particles is 50 HV or more and 200 HV or less.

2. The sliding material according to claim 1 .

4. The resin is a fluororesin.

2. The sliding material according to claim 1 .

5. The first particles are at least one of copper, an alloy mainly composed of copper, aluminum, and an alloy mainly composed of aluminum.

2. The sliding material according to claim 1 .

6. Further, the present invention includes a fiber disposed in the resin.

2. The sliding material according to claim 1 .

7. The fibers are carbon fibers.

7. The sliding material according to claim 6.

8. Further, the present invention includes a solid lubricant disposed in the resin.

2. The sliding material according to claim 1 .

9. The solid lubricant is molybdenum disulfide.

9. The sliding material according to claim 8.

10. A chemical conversion layer is formed between the resin and the first particles.

2. The sliding material according to claim 1 .

11. A chamber for performing at least one of compression and expansion of a gas; a sliding portion including a sliding member that slides on a sliding surface that defines the chamber; Equipped with The sliding material is Resin and First particles arranged in the resin and made of an inorganic material; second particles arranged in the resin and made of an inorganic material having a Vickers hardness greater than that of the first particles; When a value obtained by dividing the Vickers hardness of the second particles by the Vickers hardness of the first particles is defined as a hardness ratio, and a value obtained by dividing the content of the first particles relative to the resin by the content of the second particles relative to the resin is defined as a content ratio, The value obtained by dividing the hardness ratio by the content ratio is 0.3 or more and 2.8 or less, The second particles are at least one of alumina, silica, zinc oxide, and silicon carbide. A gas compression machine characterized by:

12. The sliding surface is a surface of an anodized aluminum layer.

12. A gas compression machine according to claim 11.

13. The sliding material slides on the sliding surface in an oil-free manner.

12. A gas compression machine according to claim 11.

Images