Sliding material and fluid machine

Abstract

To provide a sliding material that can suppress falling out of a fiber material at the time of sliding.SOLUTION: A sliding material 12 is constituted of a composite material 12c including a resin material 12a that is a base material and a fiber material 12b1 disposed inside of the resin material 12a and includes a sliding surface 12d at the surface of the composite material 12c. The number of fiber materials 12b oriented in a direction within ±45° relative to an axis L1 extending in a direction perpendicular to the sliding surface 12d is 50% or more relative to the overall number of fiber materials 12b included in the composite material 12c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sliding material and a fluid machine. [Background technology]

[0002] Generally, gas compressors that compress gas such as air include reciprocating gas compressors and scroll gas compressors. For example, in a reciprocating gas compressor, a piston ring is attached to a piston that reciprocates in a metal cylinder as a sliding member that slides against the inner surface of the cylinder. In a scroll gas compressor, a chip seal is attached to each end of a metal fixed scroll and an orbiting scroll that orbits against the fixed scroll and slides in contact with the fixed scroll.

[0003] The abstract of Patent Document 1 states that "A rotating cylinder member 2 and a piston holding member 5 are rotatably supported by a casing and a case top lid, respectively, and pistons 3, 4 are held at a rotation center position eccentric from the rotation center position of the piston holding member 5 so as to be rotatable around that position, and the pistons 3, 4 themselves rotate around the rotation center position and around the rotation center position due to relative rotation between the rotating cylinder member 2 and the piston holding member 5, and move in and out of the cylinder chambers 23a-23d, and the casing is provided with suction ports and discharge ports connected to the cylinder chambers 23a-23d, and the pistons 3, 4 are made of a resin material containing carbon nanofibers." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-270506 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the pistons 3 and 4 described in Patent Document 1, the orientation of the carbon nanofibers is not controlled. Therefore, when the pistons 3 and 4 slide, the carbon nanofibers may easily fall off from the pistons 3 and 4. The problem to be solved by the present disclosure is to provide a sliding material and a gas compressor capable of suppressing the falling off of fiber material during sliding. [Means for solving the problem]

[0006] The sliding material of the present disclosure is constituted by a composite material including a resin material as a base material and a fiber material disposed inside the resin material, the composite material has a sliding surface on its surface, and the number of fiber materials oriented in a direction within ±45° with respect to an axis extending in a direction perpendicular to the sliding surface is 50% or more of the total number of the fiber materials contained in the composite material. Other solutions will be described later in the description of the embodiment of the invention. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a sliding material and a gas compressor capable of suppressing the falling off of fibrous material during sliding. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a sliding portion in a fluid machine according to an embodiment; [Diagram 2] FIG. 1 is a diagram showing an ideal orientation of fiber material. [Figure 3A] FIG. 1 is a diagram showing a state in which a molten composite material flows within a mold. [Figure 3B] 3B is a cross-sectional view of the composite material obtained by cutting along the thin solid arrow in FIG. 3A. [Figure 4] 1 is a cross-sectional view showing a configuration of a scroll-type gas compressor as an example of a fluid machine. [Diagram 5] 5 is an enlarged view of a portion of the fixed scroll and the orbiting scroll of the gas compressor shown in FIG. 4. [Figure 6]FIG. 11 is a diagram showing a gas compression section constituting a reciprocating gas compressor as another embodiment of the fluid machine. [Figure 7] FIG. 1 is a diagram illustrating a method for a friction test. [Figure 8] FIG. 13 is a diagram showing the results of wear volume obtained in a friction test. [Figure 9] FIG. 1 is a diagram showing the results of the coefficient of friction obtained in a friction test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a form for carrying out the present disclosure (referred to as an embodiment) will be described with reference to the drawings. In the following description of one embodiment, other embodiments applicable to the one embodiment will also be described as appropriate. The present disclosure is not limited to the following one embodiment, and different embodiments can be combined with each other or modified as desired without significantly impairing the effects of the present disclosure. In addition, the same symbols will be used for the same members, and duplicate descriptions will be omitted. Furthermore, the same names will be used for members having the same functions. The contents shown are merely schematic, and for convenience of illustration, changes may be made from the actual configuration within a range that does not significantly impair the effects of the present disclosure, and some members may be omitted or modified between drawings. In addition, it is not necessary for the same embodiment to have all the configurations.

[0010] FIG 1 is a cross-sectional view showing a sliding portion 10 in a fluid machine 100 according to an embodiment. The fluid machine 100 is, for example, a gas compressor that compresses a gas. The gas compressor may be, for example, a scroll type or a reciprocating type. The specific structure of the gas compressor will be described later with reference to FIG 4 etc.

[0011] The sliding part 10 includes a metal member 11, such as a metal cylinder, and a sliding material 12, such as a piston ring. The sliding material 12 is fitted onto the outer periphery of a piston, for example. In the sliding part 10, the sliding material 12 comes into contact with the member 11 at a sliding surface 11c and slides thereon. The sliding surface 11c is formed on the surface of the member 11. The sliding form between the sliding material 12 and the member 11 may be a reciprocating motion, a circular motion, or an approximately circular motion that is not strictly a circular motion but is similar to a circular motion.

[0012] The sliding material 12 is composed of a composite material 12c. The composite material 12c includes a resin material 12a as a base material and a fiber material 12b arranged inside the resin material 12a. The fiber material 12b is dispersed, for example, inside the resin material 12a, preferably uniformly. The sliding material 12 has a sliding surface 12d on the surface of the composite material 12c. The sliding surface 12d faces the sliding surface 11c, and the sliding surface 12d slides against the sliding surface 11c.

[0013] The resin material 12a can be made of any resin. For example, the resin material 12a can be a fluororesin, and at least one of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF) can be used as the fluororesin. For example, two or more of PTFE and other fluororesins can be used in combination. In addition, the resin material 12a can be a resin other than fluororesin, and examples of the resin include polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS), and modified versions of these. The resin material 12a can be a resin other than fluororesin, and for example, PTFE and a fluororesin other than PTFE can be mixed and used in combination. In addition, the resin material 12a does not have to be a fluororesin, and can be any other resin.

[0014] Among them, the resin material 12a preferably contains at least one of polyphenylene sulfide, polytetrafluoroethylene, and polyether ether ketone. By containing these, the durability of the sliding material 12 can be particularly improved. Among them, PTFE has high crystallinity and low shear strength. Therefore, when PTFE is subjected to shear, the surface layer is easily peeled off at a micro level and transferred to the mating surface (sliding surface) such as the inner surface of a cylinder, thereby improving the sliding property.

[0015] The fiber material 12b can be made of any material as long as it is a fibrous structure. Examples of the fiber material 12b include carbon fiber, glass fiber, metal fiber, and ceramic fiber. Examples of the carbon fiber that can be used include pitch-based carbon fiber and PAN-based carbon fiber. The fiber material 12b may be one type or two or more types in combination.

[0016] Among them, it is preferable that the fiber material 12b contains carbon fiber. Since the carbon fiber is soft to a certain extent, it is less aggressive to the sliding surface 11c and causes less damage to the sliding surface 11c during sliding. This improves the durability of the sliding surface 11c. Furthermore, when the carbon fiber is worn down by sliding, a carbon film is formed on the sliding surface 11c. This improves the lubricity of the sliding surface 11c. Therefore, by including the carbon fiber, it is possible to obtain an excellent effect on wear resistance. Furthermore, due to the high affinity between the carbon fiber and the resin material 12a, it is possible to make it difficult for the carbon fiber to fall off during sliding.

[0017] The type of fiber material 12b can be easily identified by performing morphological observation and chemical analysis using a scanning electron microscope, energy dispersive X-ray analysis, infrared spectroscopy, X-ray diffraction, etc. on samples such as the surface of the slide material 12 and crushed pieces of the slide material 12.

[0018] The fiber material 12b preferably has a solid rod shape with a fiber length longer than the diameter thereof. With such a shape, the fiber material 12b embedded in the resin material 12a can support the load received from the sliding surface 11c when the sliding material 12 slides.

[0019] The diameter (fiber diameter) of the fiber material 12b is, for example, preferably 2 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less. Although details will be described later, in the present disclosure, the fiber material 12b is disposed inside the resin material 12a along the wear direction. Therefore, by setting the fiber diameter within this range, the fiber material 12b can bear the load received from the sliding surface 12d through a surface with a relatively wide area. This makes it easier to support the load applied to the fiber material 12b, and prevents the fiber material 12b from falling off the resin material 12a. This effect is particularly noticeable in harsh environments such as high pressure and high temperature.

[0020] The length (fiber length) of the fiber material 12b is, for example, preferably 1 μm to 1000 μm, more preferably 50 μm to 1000 μm, and even more preferably 100 μm to 250 μm. By setting the fiber length within this range, the length of the fiber material 12b is sufficiently maintained even if the sliding material 12 is worn down due to sliding, so that the fiber material 12b is unlikely to fall off the resin material 12a.

[0021] The diameter and length of the fiber material 12b can be measured, for example, based on image analysis. Specifically, the diameter and length of the fiber material 12b are preferably measured by, for example, selecting a plurality of (e.g., five) fiber materials 12b in a cross-sectional micrograph and adopting the average values ​​of the diameter and length of each of the selected fiber materials 12b. Note that, since a cross-sectional micrograph is usually a two-dimensional image, it is possible that the diameter and length of the fiber material 12b cannot be measured for the same fiber material 12b. For this reason, the diameter and length do not need to be measured for the same fiber material 12b, and may be measured for different fiber materials 12b.

[0022] In the sliding material 12 of the present disclosure, the number of fiber materials 12b oriented in a direction within ±45° to the axis L1 extending in a direction perpendicular to the sliding surface 12d (hereinafter referred to as the number of the present disclosure) is 50% or more of the total number of fiber materials 12b included in the composite material 12c. That is, when the axis extending in the extension direction of the fiber materials 12b is the axis L2, the number of fiber materials 12b (the number of the present disclosure) in which the angle θ between the axis L1 and the axis L2 is within 45° is 50% or more based on the total number of fiber materials 12b included in the composite material 12c. Hereinafter, the ratio of the number (amount, number) of fiber materials 12b oriented in a direction within ±45° to the axis L1 to the total number (total amount, total number) of fiber materials 12b included in the composite material 12c is appropriately referred to as "orientation of fiber materials 12b, orientation of the present disclosure", etc. Therefore, in the present disclosure, the orientation of fiber materials 12b is 50% or more.

[0023] The direction perpendicular to the sliding surface 12d is the thickness direction of the sliding material 12, and is also the wear direction of the sliding material 12. The orientation direction of the fiber material 12b is also the longitudinal direction of the fiber material 12b.

[0024] By controlling the orientation of the fiber material 12b in this manner, the fiber material 12b can be arranged along the wear direction (extension direction of the axis L1) of the composite material 12c (sliding material 12). This can reduce the effect of the load on the side surface of the fiber material 12b during sliding. In other words, the load can be mainly received by the end surface (e.g., the circular upper surface) of the fiber material 12b during sliding, and the fiber material 12b can be prevented from falling off. As a result, the wear resistance of the sliding material 12 can be improved, and friction during sliding (e.g., the friction coefficient described below) can be reduced.

[0025] The orientation of the fiber material 12b in the sliding material 12 can be confirmed by observing the morphology of a cross section in the thickness direction of the sliding material 12 using a scanning electron microscope or the like, and calculating the directionality of each fiber material 12b in the observed cross section by image analysis. At this time, the orientation of the fiber material 12b may be confirmed for the entire cross section of the sliding material 12, but for simplification, the orientation of the fiber material 12b may be confirmed based on only a portion (for example, one arbitrary piece) of a cross-sectional micrograph, and the result may be used to consider the orientation of the fiber material 12b in the entire cross section of the sliding material 12.

[0026] The angle θ can be determined as follows: For example, in a cross-sectional photograph taken with a scanning electron microscope, an axis L2 indicating the extension direction of the fiber material 12b is determined by a suitable approximation method or the like, and the angle θ can be measured as the angle between the axis L1 and the axis L2.

[0027] Fig. 2 is a diagram showing an ideal orientation of the fiber material 12b. Ideally, it is preferable that all of the fiber material 12b faces the same direction as the axis L1. In other words, it is preferable that the axis L1 and the axis L2 are parallel, and the angle θ (Fig. 1) is 0°. In this way, when the sliding material 12 wears, the load received from the sliding surface 11c can be received by the end face of the fiber material 12b (the face on the sliding surface 12d side), making it particularly difficult for the fiber material 12b to fall off.

[0028] However, in reality, such orientation control is often difficult (however, the present disclosure does not exclude the form shown in FIG. 2). Therefore, taking into consideration the effort and ease of orientation control, the number of fiber materials 12b oriented in a direction preferably within ±30°, more preferably within ±15°, with respect to axis L1 is 50% or more of the total number of fiber materials 12b contained in composite material 12c. In other words, it is preferable that the number of fiber materials 12b having axes L2 whose angle θ is preferably within 30°, more preferably within 15°, is 50% or more of the total number of fiber materials 12b contained in composite material 12c.

[0029] 1, the number of the above-mentioned fibers according to the present disclosure is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more of the total number of fiber materials 12b contained in the composite material 12c (based on the total number of fiber materials 12b contained in the composite material 12c). In this way, as many fiber materials 12b as possible can be arranged along the axis L1, making it more difficult for the fiber materials 12b to fall off.

[0030] The reason for controlling the orientation of the fiber material 12b will be explained. The inventors conducted numerous friction tests and found that there is a correlation between the wear of the sliding material 12, which is a composite resin, and the orientation of the fiber material 12b. Specifically, it was identified that when the number of the above-mentioned present disclosure is less than 50% of the total number of the fiber material 12b contained in the composite material 12c, the shear strength of the sliding material 12 is significantly reduced. Furthermore, it was confirmed that in this case, the fiber material 12b falls off from the sliding material 12, and the effect of supporting the shear stress by the fiber material 12b is lost. As a result, it was clarified that wear increases due to the abrasive action of the fallen fiber material 12b. It was also confirmed that the abrasive action tends to increase friction because it impairs the smoothness of the surface of the sliding material 12.

[0031] On the other hand, when the number of the above-mentioned present disclosure is 50% or more of the total number of the fiber materials 12b contained in the composite material 12c, the decrease in the shear strength of the sliding material 12 is suppressed, and the durability of the composite material 12c itself is maintained. In addition, the fiber materials 12b are oriented so as to be embedded in the sliding material 12 (ideally, in a direction perpendicular to the sliding surface 12d, as shown in FIG. 2, for example) against the shear stress. Therefore, the contact area between the fiber materials 12b and the sliding material 12 at the sliding surface 12d increases. This suppresses the fiber materials 12b from falling off. As a result, it has been revealed that the effect of supporting the shear stress by the fiber materials 12b is maintained and the abrasive action is also reduced, thereby reducing wear and friction.

[0032] As described above, by appropriately controlling the orientation of the fiber material 12b in the sliding material 12, the shear strength of the composite material 12c can be maintained and the abrasive action of the fallen fiber material 12b can be reduced. This contributes to improving the wear resistance of the sliding material 12 and reducing friction.

[0033] For example, the "pistons 3 and 4" described in Patent Document 1 may be made of various resins as a base material and contain carbon nanotubes (hereinafter referred to as CNTs). CNTs have a smaller diameter than fiber materials such as carbon fibers. Therefore, they cannot effectively support shear stress in harsh environments such as high pressure and high temperature. In addition, CNTs have a small diameter and a short length, so the contact area with the base material is small. Therefore, they are prone to falling off from the base material and being worn away by abrasive action, especially in harsh environments.

[0034] As described above, by controlling the orientation of the fiber material 12b in the sliding material 12, it is possible to improve the wear resistance of the sliding material in a harsh environment while reducing friction.

[0035] The orientation control of the fiber material 12b can be performed, for example, as follows, but the method of orientation control is not limited to the following example.

[0036] Fig. 3A is a diagram showing a state in which molten composite material 12c flows within a mold 70. Fig. 3B is a cross-sectional view of composite material 12c obtained by cutting at the portion indicated by the thin solid arrow in Fig. 3A. In Fig. 3A, the outline arrow indicates the flow direction of molten composite material 12c.

[0037] When a composite material 12c containing a resin material 12a and a fiber material 12b is injection molded in a mold 70, for example, the composite material 12c flows from one direction to another direction in the mold 70, away from the injection port (injection port) of the composite material 12c, as shown by the white arrow. Due to the flow, the fiber material 12b in the composite material 12c is generally arranged along the flow direction of the composite material 12c (i.e., the longitudinal direction of the fiber material 12b faces the flow direction). Therefore, in the solidified composite material 12c, the orientation direction of the fiber material 12b is generally the same direction. Therefore, the orientation of the fiber material 12b is confirmed by a cross-sectional micrograph of the composite material 12c molded in this way. Then, the orientation of the fiber material 12b in the sliding material 12 can be controlled by, for example, cutting the composite material 12c at the part indicated by the thin solid arrow so that the orientation of the fiber material 12b is in a desired direction.

[0038] Returning to FIG. 1, the content of the fiber material 12b in the composite material 12c (the content of the fiber material 12b in the composite material 12c) is preferably 5% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less. By setting the content of the fiber material 12b in this range, the aggregation of the fiber material 12b inside the composite material 12cb can be suppressed, and the fiber material 12b can be dispersed and easily applied with a load. In addition, the rigidity of the molten composite material 12c during the above-mentioned injection molding can be suppressed from becoming excessively high, and injection molding can be easily performed, so that the orientation control of the fiber material 12b can be easily performed. The content of the fiber material 12b can be measured based on, for example, thermal analysis using a simultaneous thermal mass-differential heat measurement device, mass change evaluation, etc.

[0039] The composite material 12c may contain any additive other than the resin material 12a and the fiber material 12b. For example, the composite material 12c may contain a solid lubricant (not shown) disposed in the resin material 12a. The solid lubricant is preferably in particulate form and is disposed, preferably dispersed, in the resin material 12a.

[0040] Examples of the solid lubricant include at least one of polytetrafluoroethylene (PTFE), molybdenum disulfide, graphite, and boron nitride. The inclusion of the solid lubricant can improve the sliding properties. It is preferable that PTFE is included as the solid lubricant when the resin material 12a is a resin material other than PTFE. Even when the resin material 12a is PTFE, it is preferable that the PTFE constituting the resin material 12a and the PTFE constituting the solid lubricant have different physical properties, such as number average molecular weight and degree of polymerization.

[0041] Among them, the solid lubricant preferably contains at least one of polytetrafluoroethylene, molybdenum disulfide, and graphite, which can particularly improve the lubricity of the sliding material 12.

[0042] The solid lubricant may have a particle shape in which the average particle size measured by a laser diffraction particle size distribution analyzer is 10 μm or more and 500 μ or less.

[0043] The composite material 12c may include a metal material (not shown, e.g., a filler) disposed in the resin material 12a. The metal material is preferably in the form of particles and is disposed, preferably dispersed, in the resin material 12a. Examples of the metal material include at least one of copper, copper alloy, aluminum, aluminum alloy, and the like. In particular, the metal material preferably includes at least one of copper and copper alloy. By including these, the wear resistance of the sliding material 12 can be particularly improved.

[0044] The metal material may have a particle shape with an average particle size of 10 μm or more and 500 μm or less as measured by a laser diffraction particle size distribution analyzer, for example.

[0045] The composite material 12c can include at least one of ceramics, carbon, etc. By including these, it is possible to obtain the same effect as a metal material. These materials can have a particle shape with an average particle size of 10 μm or more and 500 μ or less based on a laser diffraction particle size distribution measurement device, for example.

[0046] The sliding surfaces (sliding interfaces) 11c and 12d may contain lubricants such as lubricating oil, grease, etc. However, it is preferable that the fluid machine 100 is a fluid machine that is particularly effective when used in an oil-less state without sufficient lubricating oil, etc., or when used in an oil-free state without any lubricating oil, etc.

[0047] The member 11 preferably has a surface treatment layer 11b on the surface of the metal material 11a as a base material. That is, a sliding surface 11c, which is the further surface of the surface treatment layer 11b, comes into contact with a sliding surface 12d, and the sliding material 12 slides. However, the member 11 does not necessarily have to have the surface treatment layer 11b, and the metal material 11a may be exposed without having the surface treatment layer 11b. Therefore, the sliding surface 11c, which is the surface of the member 11, may be formed of the metal constituting the metal material 11a, or may be formed of the surface treatment layer 11b.

[0048] The metal material 11a may be at least one of light metals such as aluminum, magnesium, and silicon, and transition metals such as iron, chromium, nickel, molybdenum, titanium, and copper. Specific examples of the metal material 11a include: Aluminum, aluminum alloys and other aluminum-based materials, Iron, iron-nickel alloys and other ferrous materials, Titanium, titanium alloys and other titanium-based materials, Copper, copper alloys and other copper-based materials, At least one of the above can be used. Among them, when an aluminum-based material is used, excellent effects can be obtained in terms of wear resistance. The aluminum-based material may contain, for example, a small amount of magnesium, silicon, etc. Also, the iron-based material may contain, for example, chromium, nickel, molybdenum, etc.

[0049] The surface treatment layer 11b is, for example, a natural oxide film naturally formed on the metal material 11a, an artificially applied surface coating, etc. In other words, the surface treatment layer 11b may be a layer formed by natural processing in the natural environment, or a layer artificially processed by any surface treatment (for example, sulfuric acid anodizing). In the case of a natural oxide film, for example, if the metal material 11a is aluminum, the surface treatment layer 11b is made of aluminum oxide, if the metal material 11a is iron, it is made of iron oxide, and if the metal material is copper, it is made of copper oxide.

[0050] When the surface treatment layer 11b is a surface coating layer, for example, the surface coating layer can be formed by plating, physical vapor deposition (PVD), chemical vapor deposition (CVD), carburization, etc. The surface coating layer is made of a material containing at least one of aluminum, phosphorus, chromium, iron, nickel, and zinc. Examples of surface coatings containing such elements include anodizing, aluminum plating, nickel plating, chromium plating, iron plating, and zinc plating.

[0051] 4 is a cross-sectional view showing a configuration of a scroll-type gas compressor 20 as an example of fluid machinery 100. Gas compressor 20 includes a casing 23 forming an outer shell of gas compressor 20, a drive shaft 24 rotatably provided in casing 23, a fixed scroll 21 attached to casing 23, and an orbiting scroll 22 rotatably provided on a crankshaft 24A of drive shaft 24.

[0052] The fixed scroll 21 includes 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 includes a orbiting end plate 22a and a orbiting scroll wrap 22b formed in a spiral shape on one main surface side of the orbiting end plate 22a. The orbiting scroll 22 includes a boss portion 22f protruding from the center of the back side of the orbiting end plate 22a.

[0053] The orbiting scrolls 22 are disposed opposite to each other so that the orbiting scroll wrap 22b and the fixed scroll wrap 21b mesh with each other, thereby forming a compression / expansion chamber 25 as a working space for compressing or expanding gas between the fixed scroll wrap 21b and the orbiting scroll wrap 22b.

[0054] The compression / expansion chamber 25 is provided in the gas compressor 20 (an example of a fluid machine 100), and is an example of a chamber that performs at least one of compression and expansion. However, the compression / expansion chamber 25 may be a chamber that performs both compression and expansion. The sliding portion 30 is provided in the gas compressor 20, and includes a sliding member 12 that slides on a sliding surface 12d that defines the compression / expansion chamber 25. The sliding member 12 is a chip seal 291, 292 described below. The sliding surface 12d is a wrap bottom surface 21e, 22e (FIG. 5) described below.

[0055] An intake port 26 is formed on the outer periphery of the fixed head 21a. The intake port 26 communicates with the compression / expansion chamber 25 on the outermost periphery. A discharge port 27 is formed in the center of the fixed head 21a. The discharge port 27 opens into the compression / expansion chamber 25 on the innermost periphery.

[0056] The drive shaft 24 is rotatably supported by 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 form the crankshaft 24A. The axis of the crankshaft 24A is eccentric with respect to the axis of the drive shaft 24 by a predetermined dimension.

[0057] An annular thrust receiving portion 31 is provided on the inner circumference on the side of the orbiting scroll 22. A thrust plate 32 is provided between the thrust receiving portion 31 and the orbiting end plate 22a. The thrust plate 32 is formed as an annular plate body made of a metal material such as iron. When the orbiting scroll 22 orbits, the surface of the orbiting scroll 22 slides against the orbiting end plate 22a. At this time, the thrust plate 32, together with the thrust receiving portion 31, receives a load in the thrust direction (the direction in which the orbiting scroll 22 moves away from the fixed scroll 21) acting on the orbiting scroll 22 mainly during compression operation. This suppresses galling, abnormal wear, and the like between the casing 23 and the orbiting end plate 22a.

[0058] An Oldham ring 33 is provided between the thrust receiving portion 31 and the orbiting end plate 22a at a position closer to the center than the thrust plate 32. When the orbiting scroll 22 is rotationally driven by the drive shaft 24, the Oldham ring 33 suppresses the rotation of the orbiting scroll 22 and imparts a circular motion with a predetermined orbital radius to the crankshaft 24A.

[0059] When the drive shaft 24 is rotated by an electric motor (not shown) or the like, the orbiting scroll 22 orbits with a predetermined orbital radius. As a result, the outside air sucked in from the suction port 26 is compressed in the compression / expansion chamber 25 defined between the fixed scroll wrap 21b and the orbiting scroll wrap 22b. The generated compressed air is discharged from the discharge port 27 of the fixed scroll 21 to an external air tank (not shown) or the like.

[0060] Fig. 5 is an enlarged view of a portion of the fixed scroll 21 and the orbiting scroll 22 of the gas compressor 20 shown in Fig. 4. A groove 21d is formed in an end face 21c of the fixed scroll wrap 21b facing the orbiting end plate 22a, and a tip seal 291 (sliding material) is fitted into the groove 21d. A groove 22d is also formed in an end face 22c of the orbiting scroll wrap 22b facing the fixed end plate 21a, and a tip seal 292 (sliding material) is also fitted into the groove 22d.

[0061] As the orbiting scroll 22 orbits, the tip seal 291 slides against the wrap bottom surface 21e (sliding surface) of the orbiting end plate 22a, and the tip seal 292 slides against the wrap bottom surface 22e (sliding surface) of the fixed end plate 21a. This makes it possible to suppress contact between the fixed scroll wrap 21b and the wrap bottom surface 21e, and between the orbiting scroll wrap 22b and the wrap bottom surface 22e, thereby obtaining a smooth sliding state.

[0062] In Fig. 5, the fixed scroll 21 and the orbiting scroll 22 correspond to the member 11 in Fig. 1. The fixed scroll 21 and the orbiting scroll 22 (particularly the wrap bottom surfaces 21e, 22e) are made of an aluminum-based material such as aluminum or an aluminum alloy. The wrap bottom surfaces 21e, 22e, together with the fixed scroll wrap 21b and the orbiting scroll wrap 22b, define a compression / expansion chamber 25. An anodized aluminum layer (not shown) is formed on each surface of the fixed scroll 21 and the orbiting scroll 22 as an example of the surface treatment layer 11b (Fig. 1). Therefore, in the gas compressor 20, the sliding surface 11c is formed on the surface of an aluminum member containing aluminum and is the surface of the anodized aluminum layer.

[0063] In the sliding portion 30 between the thrust plate 32 and the swiveling mirror plate 22a, the surface of the thrust plate 32 or the surface of the swiveling mirror plate 22a forming the sliding surface thereof may be coated with the composite resin material described above. Also, in the above explanation, an example was shown in which the thrust plate 32 is made of a metal material such as iron, but the thrust plate 32 itself may be made of the sliding material 12 (composite resin material).

[0064] In the above description, gas compressor 20 is provided with a mechanism (rotation suppression mechanism) for suppressing rotation of orbiting scroll 22 by thrust plate 32 and Oldham ring 33 provided at a position closer to the center than thrust plate 32. However, gas compressor 20 is not limited to the above description, and may be a scroll-type gas compressor provided with a rotation prevention mechanism such as an auxiliary crank, an Oldham coupling (not shown), or the like.

[0065] FIG. 6 is a diagram showing a gas compression section 40 constituting a reciprocating gas compressor 400 as another embodiment of the fluid machine 100. There are two types of gas compressors 400. The first type is a normal piston type in which a connecting rod has a bearing at the compression / expansion chamber side end and has a piston supported by the bearing so as to be able to swing. A normal piston type gas compressor compresses gas by the reciprocating motion of a piston supported by a bearing so as to be able to swing. The second type is a swing piston type in which a connecting rod has no bearing at the compression / expansion chamber side and has a piston integrated with the connecting rod. FIG. 6 shows a gas compression section 40 of the swing piston type, which is the second type, as an example.

[0066] The gas compression section 40 includes a cylinder 41 and a piston 42 that reciprocates while oscillating inside the cylinder 41. The cylinder 41 (one example of the member 11) is made of an aluminum-based material such as aluminum or an aluminum alloy. An anodized aluminum layer (not shown) is formed on an inner surface 48 of the cylinder 41 as an example of the surface treatment layer 11b (FIG. 1). However, the surface treatment layer 11b such as the anodized aluminum layer does not have to be formed. The anodized aluminum layer may be formed by natural oxidation or by anodizing. The inner surface 48 is one example of the sliding surface 11c, and is formed on the surface of an aluminum member containing aluminum, and is the surface of the anodized aluminum layer. The inner surface 48, together with the partition plate 45 and the piston 42, defines a compression / expansion chamber 44.

[0067] A piston ring 43 (an example of a sliding member 12) is fitted around the piston 42. A compression / expansion chamber 44, which is a working space for compressing or expanding a gas, is formed in the space above the piston 42 within the cylinder 41. The compression / expansion chamber 44 is provided in a gas compressor 400 (an example of a fluid machine 100), and is an example of a chamber that performs at least one of compression or expansion. However, the compression / expansion chamber 44 may be a chamber that performs both compression and expansion.

[0068] The upper end of the cylinder 41 is closed by a partition plate 45, which is provided with an intake port 45a and an exhaust port 45b. An intake valve 45c and an exhaust valve 45d are provided in the intake port 45a and the exhaust port 45b. The intake port 45a and the exhaust port 45b are each connected to a pipe (not shown).

[0069] The operating principle of gas compression is explained below. Piston 42 is integrally formed with connecting rod 46. As crankshaft 47 rotates, piston 42 moves up and down. As a result, gas is sucked into compression / expansion chamber 44 from intake port 45a, and the gas is compressed in compression / expansion chamber 44. The compressed gas (compressed gas) is discharged to the outside through discharge port 45b and collected by piping (not shown).

[0070] Sliding part 50 in gas compressor 400 will be described below. Sliding part 50 is provided in gas compressor 400 (an example of fluid machine 100), and includes piston ring 43 (an example of sliding material 12) that slides on inner surface 48 that defines compression / expansion chamber 44. Piston ring 43 is fitted onto the outer periphery of piston 42 as described above. Piston 42 is a separate part from connecting rod 46 that supports piston 42. Connecting rod 46 may be made of metal or resin. Piston 42 and piston ring 43 slide on the inner circumferential surface of cylinder 41 as piston 42 reciprocates up and down.

[0071] In the above description, the reciprocating gas compressor 400 is of a rocking piston type, but is not limited thereto and may be of the normal piston type. In the normal piston type, for example, the sliding material 12 can be applied to a piston ring, a rider ring, etc. (neither of which are shown in the figures) which are sliding materials.

[0072] The gas supplied by the gas compressor 20,400 is not limited to air, but may be atmospheric air or a dry gas with an extremely small amount of water vapor. Examples of dry gas include gas with a dew point of -30°C or less. Examples of dry gas include synthetic air, high-purity nitrogen gas, oxygen gas, helium gas, argon gas, and hydrogen gas.

[0073] The sliding material 12 can exhibit sufficient wear resistance and low friction effect regardless of the type of gas to be compressed. Therefore, a gas compressor to which the sliding material 12 is applied can be used to compress, for example, dry gas. EXAMPLES

[0074] The present disclosure will now be described more specifically with reference to examples.

[0075] Through an experiment using a friction test method, the effects of improving the wear resistance and reducing friction of the sliding material 12 were confirmed.

[0076] <Materials used> In the studies of Examples 1 to 3 and Comparative Examples 1 and 2, polyphenylene sulfide (PPS) was used as the resin material 12a (FIG. 1), and carbon fiber was used as the fiber material 12b (FIG. 1). The content of the fiber material 12b in the composite material 12c (FIG. 1) was 10 mass%. The length and diameter of the carbon fiber were 130 μm and 12 μm, respectively, as the average length and average diameter based on the above measurement method.

[0077] In Examples 1 to 3, the orientation of the fiber material 12b (orientation according to the present disclosure) was set to 50% or more. Specifically, it was 75% in Example 1, 60% in Example 2, and 50% in Example 3. On the other hand, in Comparative Examples 1 and 2, the orientation of the fiber material 12b (orientation according to the present disclosure) was set to less than 50%. Specifically, it was 35% in Comparative Example 1, and 20% in Comparative Example 2. The materials used and the orientation of the fiber material 12b are summarized in Table 1 below.

[0078] [Table 1]

[0079] <Friction test method> Fig. 7 is a diagram for explaining the method of the friction test. Each of the composite materials 12c of Examples 1 to 3 and Comparative Examples 1 and 2 was molded into a block-shaped test piece 61. The test piece 61 imitates the above-mentioned sliding material 12 (Fig. 1). The test piece 61 was a rectangular parallelepiped with a width of 6 mm, a length of 20 mm, and a height of 5 mm, and was produced by C-chamfering two opposing sides in the longitudinal direction of the upper surface. The C-chamfering was set to 0.5 mm each.

[0080] The test piece 62 used in the friction test was prepared by the following method. The test piece 62 imitates, for example, the above-mentioned member 11 (FIG. 1). The test piece 62 was prepared by molding an aluminum alloy into a ring shape (annular, cylindrical) with an outer diameter of 13 mm and an inner diameter of 9 mm. An anodized aluminum layer was formed on the surface of the test piece 62 (particularly the lower surface) by sulfuric acid anodizing treatment.

[0081] The friction test was performed by contacting and rotating (i.e., sliding) the lower surface of a ring-shaped test piece 62 with the upper surface of a test piece 61. The test conditions were controlled as follows: contact pressure: 0.9 MPa, rotation speed: 1.9 m / s, temperature: 90° C., and rotation for 15 hours.

[0082] FIG. 8 is a diagram showing the results of the wear amount obtained in the friction test. The wear amount was the difference in mass of the test piece 61 before and after the wear test. In both FIG. 8 and FIG. 9 described later, the wear amount is expressed as a relative value when Comparative Example 2 is set to 1. In all of Examples 1 to 3, the wear amount was reduced to about 0.3 (30%) compared to Comparative Example 2. On the other hand, in Comparative Example 1, the wear amount was about 0.9 (90%) compared to Comparative Example 2, and it was found that there was no significant difference in the wear amount between Comparative Examples 1 and 2.

[0083] FIG. 9 is a diagram showing the results of the friction coefficient obtained in the friction test. The friction coefficient was calculated by dividing the mass loss (amount of wear) before and after the friction test by the density of the test piece 61. It can be said that the smaller the friction coefficient, the less likely it is to wear, and the higher the durability such as wear resistance. In all of Examples 1 to 3, the friction coefficient was reduced to about 0.6 (60%) compared to Comparative Example 2. On the other hand, Comparative Example 1 was almost the same as Comparative Example 2, and it was found that there was no significant difference in the friction coefficient.

[0084] From these results, it was found that the wear amount and the friction coefficient can be reduced by controlling the orientation of the fiber material 12b (the orientation of the present disclosure) to 50% or more. In particular, as shown in FIG. 9, completely different results were obtained between Examples 1 to 3 and Comparative Examples 1 to 2 at the boundary of 50%, and the advantage of setting the orientation of the fiber material 12b to 50% or more can be confirmed from FIG. 9. Such results are considered to be the result of the fiber material 12b being difficult to come out of the resin material 12a during sliding because most of the fiber material 12b is oriented along the wear direction of the sliding material 12. And, since it is difficult to come out, the fiber material 12b can support the load from the sliding surface 12d for a long period of time, and it is considered that the abrasive action can be suppressed. Therefore, it was confirmed that by setting the orientation of the fiber material 12b to 50% or more, it is possible to simultaneously improve the wear durability of the sliding material 12 and reduce the friction coefficient.

[0085] Therefore, by applying the sliding material 12 to, for example, a tip seal of a scroll gas compressor or a piston of a reciprocating gas compressor, the wear resistance of the tip seal, piston, etc. can be improved, and the replacement life of these can be extended. In addition, loss due to friction can be reduced. As a result, the maintenance cycle and life of fluid machinery such as a scroll gas compressor or a reciprocating gas compressor can be extended and the efficiency can be improved.

[0086] On the other hand, it was found that Comparative Example 1 was almost the same as Comparative Example 2, and there was no significant difference in the amount of wear and the coefficient of friction. This result is believed to be due to the fact that the shear strength of the composite material 12c was reduced and the contact area with the resin material 12a on the sliding surface 12d was reduced, resulting in an increase in the amount of fiber material 12b falling off. As a result, it is believed that the amount of wear increased and the coefficient of friction increased due to the abrasive action. [Explanation of symbols]

[0087] 10 Sliding part 100 Fluid machinery 11 Materials 11a Metal material 11b Surface treatment layer 11c Sliding surface 12 Sliding material 12a Resin material 12b Fiber materials 12c composite material 12c composite material 12d sliding surface 20 Gas Compressor 21 Fixed Scroll 21a Fixed head plate 21b Fixed Scroll Wrap 21c end face 21d groove 21e Bottom surface of lap (sliding surface) 22 Swivel Scroll 22a Swivel head plate 22b Swivel Scroll Wrap 22c end face 22e Bottom surface of lap (sliding surface) 25 Compression and expansion chamber (chamber) 291 Chip seal (sliding material) 292 Chip seal (sliding material) 30 Sliding part 40 Gas compression section 400 Gas Compressor 41 Cylinder 42 Piston 43 Piston ring (sliding material) 44 Compression and expansion chamber (chamber) 45 Partition 48 Inner surface (sliding surface) 50 Sliding part 61,62 Test specimen L1,L2 axis

Claims

1. The bearing is made of a composite material including a resin material as a base material and a fiber material disposed inside the resin material, and has a sliding surface on the surface of the composite material; the number of fiber materials oriented in a direction within ±45° with respect to an axis extending in a direction perpendicular to the sliding surface is 50% or more of the total number of fiber materials contained in the composite material, The resin material is Fluorine resin, or At least one of polyphenylene sulfide and polyether ether ketone, is A sliding material characterized by:

2. The fibrous material has a solid rod shape with a fiber length greater than the diameter.

2. The sliding material according to claim 1.

3. The fiber length is 1 μm or more and 1000 μm or less.

3. The sliding material according to claim 2.

4. The fiber material includes carbon fiber.

2. The sliding material according to claim 1.

5. The fluororesin is polytetrafluoroethylene.

2. The sliding material according to claim 1.

6. The composite material includes a solid lubricant disposed in the resin material.

2. The sliding material according to claim 1.

7. The solid lubricant contains at least one of polytetrafluoroethylene, molybdenum disulfide, and graphite.

7. The sliding material according to claim 6.

8. The composite material includes a metal material disposed in the resin material.

2. The sliding material according to claim 1.

9. The metal material includes at least one of copper and a copper alloy.

9. The sliding material according to claim 8.

10. The content of the fiber material in the composite material is 5% by mass or more and 30% by mass or less.

2. The sliding material according to claim 1.

11. a chamber for compressing or expanding a gas; a sliding portion including a sliding member that slides on a sliding surface that defines the chamber; The sliding material is The bearing is made of a composite material including a resin material as a base material and a fiber material disposed inside the resin material, and has a sliding surface on the surface of the composite material; the number of fiber materials oriented in a direction within ±45° with respect to an axis extending in a direction perpendicular to the sliding surface is 50% or more of the total number of fiber materials contained in the composite material, The resin material is Fluorine resin, or At least one of polyphenylene sulfide and polyether ether ketone, is A fluid machine characterized by:

12. The sliding surface is It is formed on the surface of an aluminum member containing aluminum, The surface of the anodized aluminum layer The fluid machinery according to claim 11.

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