BEARING AND COMPRESSOR

Abstract

A bearing (10) comprises a tubular base material (12) and a resin layer (14). The resin layer (14) is bonded to an inner peripheral surface (C1) of the base material (12) and is provided, on a surface on a facing surface (C2) facing a shaft member accommodated so as to be opposite to the inner peripheral surface (C1) of the base material (12), with a plurality of grooves (MG) extending along a direction intersecting the extending direction (Z) of the shaft member. The resin layer (14) contains a synthetic resin (16) and additives (18) dispersed in the synthetic resin (16). The average particle size of the additive (18) is less than the depth (d) of the plurality of grooves (MG).

Description

Field of InterestThe present invention relates to a bearing and a compressor.BackgroundHeretofore, there has been known a configuration in which grooves are formed on the surface of the inner circumferential surface of a bearing in a cylindrical shape from the viewpoint of improving the seizure resistance by oil retention, etc. For example, a configuration is known in which grooves are formed on a bearing layer on a base material. Further, a configuration is disclosed in which a resin layer containing additives such as graphite is used as a storage layer provided on a base material.CitelistPatent LiteraturePatent Literature 1: Japanese Patent No. 5683571Patent Literature 2: JP 2018-193521 ASummaryTechnical ProblemA groove is formed by cutting a resin layer coated on a base material or the like. However, there is a case where formation of a groove having a target shape is difficult due to the influence of additives contained in the resin layer. In the conventional technology, therefore, normal grooving cannot be performed and seizure resistance is insufficient.An object of the present invention is to provide a bearing and a compressor capable of improving seizure resistance.Solution of the ProblemIn order to solve the above problem and achieve the object, a bearing according to the present invention includes: a tubular base material; and a resin layer bonded to an inner circumferential surface of the base material, which is provided on a surface on a facing surface facing a shaft member accommodated so as to oppose the inner circumferential surface of the base material, with a plurality of grooves that extend along a direction intersecting an extending direction of the shaft member and that contains a synthetic resin and an additive dispersed in the synthetic resin, wherein an average particle size of the additive is less than a depth of the plurality of grooves.Advantageous Effects of the InventionAccording to the present invention, the seizure resistance can be improved.Brief Description of the DrawingsFIG. 1A is an explanatory diagram of an example of an overall configuration of a bearing of an embodiment. FIG. 1B is an explanatory diagram of the example of the overall configuration of the bearing of the embodiment. FIG. 2 is an enlarged cross-sectional view of the example of the bearing. FIG. 3A is an explanatory view of an example of a method for manufacturing a bearing. FIG. 3B is an explanatory view of the example of the method for manufacturing a bearing. FIG. 4 is an explanatory view of an example of a conventional comparative bearing. FIG. 5 is a schematic diagram of an example of a compressor. FIG. 6 is an explanatory view of a seizure resistance test.DESCRIPTION OF EMBODIMENTSHereinafter, embodiments of a bearing and a compressor according to the present invention will be described in detail with reference to the accompanying drawings.The bearing of the present embodiment includes a tubular base material and a resin layer. The resin layer is bonded to the inner circumferential surface of the base material. The resin layer is provided on a surface on a facing surface facing a shaft member accommodated so as to oppose the inner circumferential surface of the base material with a plurality of grooves that extend along a direction intersecting an extending direction of the shaft member and that contain a synthetic resin and an additive dispersed in the synthetic resin. The resin layer contains a synthetic resin and additives dispersed in the synthetic resin. The average particle size of the additive is less than the depth of the groove.In the bearing of the present embodiment, the average particle size of the additive contained in the resin layer is less than the depth of the groove. Thus, the bearing of the present embodiment enables easy formation of grooves and can improve seizure resistance.Although the reason why the above effect occurs is not clear, it is presumed as follows. However, the present invention is not limited by the following assumption.When the average particle size of the additive contained in the resin layer is equal to or larger than the depth of the groove, it is considered that formation of a groove having a target shape may be difficult. In addition, when the average particle size of the additive contained in the resin layer is equal to or more than the depth of the groove, fallen portions formed by the additive fallen during processing of the grooves may form large defects in the shape of the groove, and there may be a case that no groove having the desired shape is formed. When the formation of a groove having the desired shape is difficult, it can be considered that the bearing performance including seizure resistance may not be stable, and a problem arises with the quality of the bearing product. In addition, when the average particle size of the additive contained in the resin layer is equal to or larger than the depth of the groove, a predetermined groove shape may not be maintained during sliding with the shaft member.On the other hand, when the average particle size of the additive contained in the resin layer is less than the depth of the groove, it is considered that a groove having a target shape is formed appropriately. Further, it is considered that by forming a groove having a target shape, an appropriate oil film holding force of the lubricating oil based on the groove is obtained, and the lubrication performance is improved, and the seizure resistance can be improved.Hereinafter, the bearing and the compressor of the present embodiment will be described in detail.FIGS. 1A and 1B are explanatory diagrams of an example of an overall configuration of a bearing 10 of the present embodiment. FIG. 1A is a cross-sectional view of the bearing 10 taken along a direction intersecting the extending direction Z of the bearing 10. FIG. 1B is an external view of the bearing 10 as viewed from a direction intersecting the extending direction Z of the bearing 10.The bearing 10 is made of a base material 12 and a resin layer 14.The base material 12 is a tubular member. In the present embodiment, a shape in which the base material 12 is a cylindrical member will be described as an example. The base material 12 only needs to have a tubular shape, and is not limited to a cylindrical shape.The base material 12 is a member for receiving a shaft member 30 on the inner circumferential surface C 1 side. The shaft member 30 is a rod-shaped member long in the extending direction Z. In the present embodiment, a shape in which the extending direction Z of the base material 12 and the extending direction Z of the shaft member 30 coincide with each other will be described as an example. The extending direction Z of the base material 12 and the extending direction Z of the shaft member 30 may not coincide with each other.The resin layer 14 is a layer bonded to the inner circumferential surface C 1 of the base material 12. A surface of the resin layer 14 on the side of the facing surface C 2, the facing surface C 2 facing the shaft member 30, is provided with a plurality of grooves MG extending along a direction intersecting the extending direction Z of the shaft member 30. The groove MG extending along a direction intersecting the extending direction Z means a groove MG extending along a direction intersecting the extending direction Z.The groove MG need only be provided along a direction intersecting the extending direction Z of the shaft member 30, and may be either a direction orthogonal to the extending direction Z or a direction inclined at an angle of less than 90° with respect to the orthogonal direction. In the present embodiment, a shape in which the groove MG is provided along a direction orthogonal to the extending direction Z of the shaft member 30, that is, along the circumferential direction Q of the bearing 10 in a cylindrical shape will be described as an example. A configuration in which a groove MG is continuously spirally formed from one end portion to another end portion in the extending direction Z of the resin layer 14 is possible. Also, a configuration in which the resin layer 14 is provided with a plurality of grooves MG that are not continuous to each other from its one end side to its other end side in the extending direction Z is possible.Details of the bearing 10 will be described below.FIG. 2 is an enlarged cross-sectional view of an example of the bearing 10.The bearing 10 is a stacked body of the base material 12 and the resin layer 14 formed on the base material 12.The base material 12 is a layer that gives mechanical strength to the bearing 10. The base material 12 may also be referred to as a counter metal or counter metal layer. As the base material 12, for example, a metal plate made of an Fe alloy, Cu, a Cu alloy, or the like can be used.At least a portion of the base material 12 on the contact surface side in contact with the resin layer 14 may be formed by a sintered layer. The sintered layer is a sintered body made of metal powder, and is a porous layer having a plurality of pores. The metal powder constituting the sintered layer may be the same metal as the base material 12, or may be a metal or a material different from the base material 12. By using a sintered layer configuration, adhesion between the base material 12 and the resin layer 14 can be improved.The resin layer 14 is, as described above, a layer bonded to the inner circumferential surface C 1 of the base material 12. As described above, a surface of the resin layer 14 on the side C 2 facing the shaft member 30 is provided with the groove MG.The groove MG is a fine, precise micro-level groove portion formed on the surface of the resin layer 14. The groove MG may also be referred to as a micro groove.The shape of the groove MG is not limited. The groove MG only needs to be formed so as to be able to receive lubricating oil supplied upon rotational driving of the bearing 10 or on similar occasions, and to be able to receive the oil between the groove MG and the shaft member 30.FIG. 2 shows, as an example, a shape in which the cross-sectional shape of the groove MG is a V-shape. However, the cross-sectional shape of the groove MG is not limited to a V-shape. The cross-sectional shape of the groove MG may be, for example, a U-shape, a shape consisting of a flat bottom part and a pair of side wall parts erected with respect to the bottom part, or the like.The depth d of the groove MG and the width of the groove MG are not limited. The depth d and the width of the groove MG need only be a depth and a width with which lubricating oil supplied upon rotational driving of the bearing 10 or on similar occasions can be retained and the oil can be retained between the groove MG and the shaft member 30.The depth d of the groove MG refers to the distance in the thickness direction of the resin layer 14 between the bottom B of the groove MG and the apex T of the tip of the groove MG. The width of the groove MG refers to the distance between the centers of the bottoms B of the adjacent grooves MG.The depth d of the groove MG is, for example, in the range of 40 μm or more and 7.0 μm or less, but is not limited to this range. The width of the groove MG is, for example, in the range of 0.045 mm or more and 0.145 mm or less, preferably 0.075 mm or more and 0.095 mm or less, but is not limited to this range. The grooves MG are continuously formed in the width direction.The resin layer 14 is a layer containing a resin material as a main component. Specifically, the resin layer 14 is made of a synthetic resin 16 and additives 18 dispersed in the synthetic resin 16.The composition of the synthetic resin 16 is not limited. The composition of the synthetic resin 16 is preferably made of a heat-resistant resin from the viewpoint of improving abrasion resistance or the like.The synthetic resin 16 contains, for example, PTFE (polytetrafluoroethylene). In the present embodiment, a form in which PTFE particles 16A which are particulate PTFE are dispersed in the synthetic resin 16 is exemplified.The content of PTFE particles 16A in the synthetic resin 16 is not limited. For example, the content of PTFE particles 16A in the synthetic resin 16 is preferably equal to or more than 5 volume percent and equal to or less than 30 volume percent, more preferably equal to or more than 10 volume percent and equal to or less than 25 volume percent, and particularly preferably equal to or more than 12 volume percent and equal to or less than 20 volume percent.When the content of the PTFE particles 16A in the synthetic resin 16 is in the above range, the friction coefficient of the resin layer 14 can be reduced. In addition, the PTFE particles 16A have high heat resistance and are difficult to melt and decompose. By using a configuration in which PTFE particles 16A are incorporated into the synthetic resin 16, the friction coefficient of the resin layer 14 can be effectively reduced. That is, by the PTFE particles 16A, the seizure resistance of the bearing 10 can be further improved.The average particle size of the PTFE particles 16A is not limited. The average particle size of the PTFE particles 16A may be either equal to or larger than the depth d of the groove MG and smaller than the depth d of the groove MG. Specifically, the average particle size of the PTFE particles 16A is, for example, preferably equal to or larger than 1.0 μm and equal to or smaller than 25.0 μm, more preferably equal to or larger than 1.0 μm and equal to or smaller than 15.0 μm, and particularly preferably equal to or larger than 0.2 μm and equal to or smaller than 12.0 μm.When the average particle size of the PTFE particles 16A is in the above range, the total area of the surface area of the PTFE particles 16A dispersed in the synthetic resin 16 is increased. Thus, the friction coefficient of the synthetic resin layer 14 can be decreased and the seizure resistance of the synthetic resin layer 14 can be improved even if the amount of the PTFE particles 16A is a smaller amount within the above range.The average particle size of the PTFE particles 16A refers to the average primary particle size of the PTFE particles 16A. The average primary particle size refers to a cumulatively 50% volume average particle size. For the measurement of the average particle size of the PTFE particles 16A, a scanning electron microscope (SEM) may be used. The particles of the PTFE particles 16A are observed by SEM observation at an appropriate magnification (e.g., about 5000 times), and the diameter of each of 100 primary particles is measured to calculate the volume of the primary particle; the cumulatively 50% particle size can be taken as the average primary particle size. When the particle of the PTFE particle 16A is not spherical, the average value of the major axis and the minor axis is regarded as the diameter of the primary particle.The shape of the PTFE particle 16A is not limited. For example, the shape of the PTFE particles 16A may be either spherical or oblong spherical. The method for producing the PTFE particles 16A is not limited. For example, all of PTFE particles produced by a suspension polymerization method, PTFE particles produced by an emulsion polymerization method, and regenerated PTFE particles can be used as the PTFE particles 16A.The synthetic resin 16 may be a configuration further including one or two or more selected from PI (polyimides), PAI (polyamide imides), PBI (polybenzimidazoles), PA (polyamides), phenol, epoxy, POM (polyacetal), PEEK (polyetheretherketone), PE (polyethylene), PPS (polyphenylene sulfide), and PEI (polyetherimide).The synthetic resin 16 may be a configuration additionally containing a silane coupling agent from the viewpoint of enhancing the bonding with the additive 18.Next, the additive 18 will be described.The additive 18 is a substance for improving the properties of the resin layer 14. That is, no resin is contained in the additive 18.The average particle size of the additive 18 of the present embodiment is smaller than the depth d of the groove MG. For example, it is essential that the average particle size of the additive 18 is less than once the depth d of the groove MG, and the average particle size is preferably less than 3 / 4 times the depth d of the groove MG, and more preferably less than 1 / 2 times the depth d of the groove MG.When the average particle size of the additive 18 is smaller than the depth d of the groove MG, it is considered that a groove MG having a target shape is appropriately formed during the manufacture of the bearing 10B. It is considered that by appropriately forming a groove MG having a target shape, an appropriate lubricating oil holding force based on the groove MG can be obtained and seizure resistance can be improved.The average particle size of the additive 18 can be measured by the following method. Specifically, for example, an electron image is obtained in which a cross section in a direction along the extending direction Z of the resin layer 14 is photographed with an electron microscope at an appropriate magnification (e.g., 1000 times). Then, the areas of the particles of the additive 18 contained in the obtained electron image are measured by a general image analysis technique for each kind of the additive 18 and converted into the average diameter, assuming that the area is a circle. The average particle size of each type of additive 18 can be determined by these processing steps.The additive 18 comprises in particular at least one of the substances graphite 20 and clay 22.By the additive 18 containing graphite 20, improvement in seizure resistance of the resin layer 14, etc. can be achieved.The average particle size of the additive 18 such as the graphite 20 need only be smaller than the depth d of the groove MG as described above. For example, it is assumed that the depth d of the groove MG is in the range of 4.0 μm or more and 7.0 μm or less. In this case, the average particle size of the graphite 20 is, for example, preferably equal to or larger than 1.0 μm and smaller than 4.0 μm, and is preferably equal to or larger than 1.0 μm and smaller than 2.0 μm.The content amount of the graphite 20 in the synthetic resin 16 is not limited. The content amount of the graphite 20 in the synthetic resin 16 is, for example, preferably equal to or more than 1 volume percent and less than 15 volume percent, more preferably equal to or more than 3 volume percent and equal to or less than 12 volume percent, and particularly preferably equal to or more than 5 volume percent and less than 9 volume percent.When the content amount of the graphite 20 in the synthetic resin 16 is within the above range, lipophilicity of the resin layer 14 can be improved and seizure resistance can be further improved.The shape of the graphite 20 is not limited. For example, the shape of the graphite 20 may be either flake-shaped or spherical. The shape of the graphite 20 is preferably flake-shaped.The scale shape means that the shape is a scale-like shape. The scale-like graphite 20 is a crystal in which a large number of AB surfaces (hexagonal cross-linked flat surfaces, basal surfaces) distributed in a planar shape by carbon atoms regularly forming a network structure are stacked, and which has a thickness in the C-axis direction perpendicular to the AB surface. Since the bonding force due to the van der Waals force between the stacked AB surfaces is much smaller than the bonding force in the in-plane direction of the AB surface, shearing forces are likely to occur between the AB surfaces. Therefore, the scale-shaped graphite 20 has a small thickness in the stacking direction with respect to the extension of the AB surface, and forms a thin plate shape as a whole.The flake graphite 20 acts as a solid lubricant by shear between AB surfaces that occur upon application of an external force. Therefore, by using flake graphite 20 as graphite 20 dispersed in synthetic resin 16, the seizure resistance of resin layer 14 can be further improved.The degree of graphitization of the graphite 20 is preferably high from the viewpoint of reducing the friction coefficient. For example, the degree of graphitization of the graphite 20 is preferably equal to or more than 95%, and more preferably equal to or more than 99%.The clay 22 is generally an Al 2 O 3- SiO 2- H 2 O-based clay mineral. The clay 22 may be calcined clay. By the additive 18 containing clay 22, the abrasion resistance of the resin layer 14 can be improved.The average particle size of the clay 22 need only be smaller than the depth d of the groove MG as described above. For example, it is assumed that the depth d of the groove MG is in the range of 4.0 μm or more and 7.0 μm or less. In this case, for example, the average particle size of the clay 22 is preferably equal to or larger than 2.0 μm and equal to or smaller than 4.0 μm, and preferably equal to or larger than 2.0 μm and smaller than 3.5 μm.The content amount of the sound 22 in the synthetic resin 16 is not limited. The content amount of the clay 22 in the synthetic resin 16 is, for example, preferably equal to or more than 1 volume percent and equal to or less than 5 volume percent, and more preferably equal to or more than 1 volume percent and equal to or less than 3 volume percent. When the content amount of the clay 22 is in the above range, the abrasion resistance of the resin layer 14 can be improved and a decrease in the fatigue strength can be suppressed.(Method for Producing a Bearing)The bearing 10 of the present embodiment is manufactured by the following steps, for example.FIGS. 3A and 3B are explanatory diagrams of an example of a method of manufacturing the bearing 10.As illustrated in FIG. 3A, the constituent elements of the resin layer 14 of the above configuration are applied to a base material 12, thereby forming a resin material layer 15 (a resin material layer forming step). Subsequently, the resin material layer 15 formed on the base material 12 is dried. As the application conditions and drying conditions, known conditions can be used.Next, a groove processing step is performed. In the groove machining step, the edge of a cutting tool is moved along the surface of the resin material layer 15, and thereby the surface of the resin material layer 15 is scraped along a cutting surface CS of a groove MG of a target shape. By the groove processing step, as illustrated in FIG. 3B, a bearing 10 including a resin layer 14 in which a groove MG is formed is manufactured.The formation of the groove MG is not limited to the formation by cutting the resin material layer 15 with a cutting tool. The groove MG may be formed by, for example, etching, a roller, or the like.Here, the additives 18 are contained in the resin material layer 15. The larger the relative size of the additive 18 contained in the resin material layer 15 with respect to the groove MG, the more difficult the processing of the groove MG may be. However, as described above, in the present embodiment, the average particle size of the additive 18 is smaller than the depth d of the groove MG. Therefore, in the present embodiment, the groove MG can be easily formed even when the additives 18 are contained in the resin material layer 15.During the formation of the groove MG, the additive 18 may fall off from the resin layer 14 due to cutting of the resin material layer 15 or the like, and fallen portions F may be formed on the surface of the resin layer 14 (see FIG. 3B ). However, as described above, in the present embodiment, the average particle size of the additive 18 is smaller than the depth d of the groove MG. Therefore, in the bearing 10 of the present embodiment, the shape of the groove MG substantially maintains the target shape (see FIG. 3B ) even when portions F fallen due to the falling of the additive 18 during the formation of the groove MG form on the surface of the resin layer 14. That is, in the present embodiment, a bearing 10 having a groove MG in which the rate of the shape defects with respect to the target shape is suppressed (i.e., a normal groove MG) can be manufactured.On the other hand, in a conventional bearing in which the average particle size of the additive 18 is equal to or larger than the depth d of the groove MG, it is difficult to form a groove MG having a target shape.FIG. 4 is an explanatory view of an example of a comparative bearing 1000. In the comparative bearing 1000, the average particle size of an additive 19 such as graphite 21 or clay 23 dispersed in a synthetic resin 16 of a comparative resin layer 17 is equal to or larger than the depth d of a groove MG. Therefore, in the comparative bearing 1000, the relative size of the additive 19 with respect to the groove MG is large, and there was a case where it was difficult to perform the processing of the groove MG on the surface of the resin material layer of the comparative resin layer 17.Further, in the comparative bearing 1000, the relative size of a fallen portion F formed by the additive 19 falling during the formation of the groove MG with respect to the groove MG is large, and as a result, a case has occurred in which a groove MG having a shape greatly deviating from a target shape is formed (see FIG. 4 ). Therefore, in the comparative bearing 1000, it is considered that a normal groove MG cannot be provided, and it is difficult to achieve stable bearing performance, and a problem arises in the quality of a bearing product.On the other hand, in the bearing 10 of the present embodiment, the average particle size of the additive 18 is smaller than the depth d of the groove MG. Therefore, in the present embodiment, the groove MG can be easily formed even when the additives 18 are contained in the resin material layer 15. Further, as illustrated in FIG. 3B, in the bearing 10 of the present embodiment, the ratio of the shape errors with respect to the target shape of the groove MG is smaller than in the conventional comparative bearing 1000, and it is assumed that a bearing 10 having a groove MG that is closer to or more agrees with the target shape can be manufactured.Therefore, in the present embodiment, it is considered that by forming a groove MG having a target shape, an appropriate lubricating oil holding force can be obtained based on the groove MG, and the seizure resistance of the bearing 10 can be improved.(Compressor)Next, an example of an application form of the bearing 10 will be described. The bearing 10 is used as a bushing in a fuel injection pump, various bearings, a compressor, or the like, for example.FIG. 5 is a schematic diagram of an example of a compressor 40. the compressor 40 is an example of an application form of the stocker 10. FIG. 5 shows a scroll compressor as an example. The scroll compressor is used for compressing a gas such as a refrigerant gas in an air conditioner for an automobile, a household, a railway, or a company.The compressor 40 is composed of a cylindrical casing 41 having both ends closed. The center of the housing 41 is arranged along a z-axis, for example. The direction of the z-axis coincides with a direction parallel to the vertical direction. The +z direction is a vertical direction and may be referred to as above. The -z direction is an anti-vertical direction and may be referred to as below.Above (in the -z direction) the housing 41, an intake pipe 44 for drawing in the atmosphere is provided. On a side surface of the housing 41, a discharge pipe 46 for discharging the compressed air stored in a chamber 45 in the housing 41 is provided. Inside the housing 41, a bearing 10 fixed to the housing 41 and a shaft member 30 rotatably supported by the bearing 10 are arranged in a direction along the z-axis. That is, FIG. 5 exemplarily shows a shape in which the extending directions Z of the shaft member 30 and the bearing 10 and the z-axis direction, which is a direction parallel to the vertical direction, coincide with each other. In other words, FIG. 5 exemplarily describes a form in which the compressor 40 is a vertical compressor.A fixed scroll member 47 provided with a scroll blade is fixed to an upper portion of the internal space of the housing 41 of the compressor 40. At the bottom of the fixed scroll member 47, a movable scroll member 48 provided with a spiral vane having the opposite winding direction to the vane of the fixed scroll member 47 is disposed so as to face the fixed scroll member 47. The movable scroll member 48 forms a compression chamber together with the fixed scroll member 47.The shaft member 30 has a crank pin 30A at the upper part. When the shaft member 30 is rotated by a motor 43 provided inside the housing 41, the crank pin 30A rotates. The crank pin 30A is accommodated in a pin receiver 48A provided below the movable scroll member 48, and rotates the movable scroll member 48 by itself rotating.When the movable scroll member 48 rotates, the atmosphere sucked from the intake pipe 44 flows into the compression chamber formed by the movable scroll member 48 and the fixed scroll member 47, is compressed, and is stored in the chamber 45. The compressor 40 discharges the compressed air stored in the chamber 45 to the outside via the discharge pipe 46.Generally, a compressor 40 (an air conditioner compressor) that compresses a refrigerant contains lubricating oil (refrigerating machine oil) in the refrigerant, and supplies the lubricating oil to each bearing 10 by circulation of the refrigerant. In the stopped state, when the refrigerant does not circulate, the lubricating oil is not supplied. Therefore, lubrication of the bearings 10 in the period between the standstill and the start of the start is performed only by oil held (adhering) between the bearings 10 and the shaft member 30.At the time of starting the compressor 40, lubrication is performed with oil held between the bearing 10 and the shaft member 30, and the shaft member 30 is rotated. If this oil is used up before the refrigerant circulates, seizure occurs.In the bearing 10 of the present embodiment, a groove MG is provided on the surface C 2 of the resin layer 14 facing the shaft member 30.Thus, the oil holding force for the lubricating oil that has entered the gap between the bearing 10 and the shaft member 30 is increased by the groove MG provided in the resin layer 14. It is therefore assumed that the resin layer 14 of the bearing 10 and the shaft member 30 are lubricated at the time of starting the compressor 40, and that a situation in which oil shortage occurs at the start of the rotation start of the shaft member 30 and seizure is caused is suppressed.It is therefore considered that the compressor 40 including the bearing 10 of the present embodiment can improve seizure resistance.FIG. 5 shows, as an example, a form in which the compressor 40 is a vertical compressor. However, the compressor 40 may be a horizontal compressor in which the extending directions Z of the shaft member 30 and the bearing 10 coincide with the horizontal direction. Further, the compressor 40 may be a shape in which the extending directions Z of the shaft member 30 and the bearing 10 are arranged in directions intersecting both the horizontal direction and the vertical direction.The timing of forming the groove MG is not limited. For example, the groove MG may be formed before the bearing 10 is attached to the compressor 40. That is, the compressor 40 can be manufactured by a method in which a bearing 10 in which a groove MG is formed is fixed to the compressor 40.Further, the groove MG may be formed by a method in which a bearing 10 having a resin material layer 15 in which no groove MG is formed is attached to the compressor 40, and then a groove processing step is performed on the resin material layer 15. As described above, in the bearing 10 of the present embodiment, the average particle size of the additive 18 contained in the resin material layer 15 is smaller than the depth d of the groove MG to be formed. Therefore, in the present embodiment, even when the additives 18 are contained in the resin material layer 15, the groove MG can be easily formed. That is, in the present embodiment, even in the case where the groove MG is formed after the bearing 10 is attached to the compressor 40, a groove MG of a target shape can be formed with ease and high accuracy.[Examples]The present invention will now be described specifically by way of Examples, but the present invention is not limited to these Examples.The following test pieces containing resin layers 14 and comparative resin layers were prepared, and the seizure resistance was evaluated for these test pieces.Preparation of a test pieceAs the base material 12, a steel sheet (SPCC (JIS)) having a thickness of 1.5 mm was prepared. A solution of the components of the resin layer 14 was prepared in which the additives shown in Examples 1 to 3 of Table 1 were added to the synthetic resins of the composition shown in Examples 1 to 3 of Table 1, respectively.Subsequently, this solution was applied to the base material 12 by the doctor blade application method. After application, drying was carried out in the range of room temperature to about 200°C for 60 to 90 minutes. Thereafter, the temperature was raised to about 300°C and fired for 30 to 90 minutes. Through these steps, a resin material layer 15 was formed on the base material 12. Further, the edge of a cutting tool was moved along the surface of the resin material layer 15, and thereby the surface of the resin material layer 15 was scraped along a cutting surface CS of a groove MG of a target shape. The target shape was set to a V-shaped cross-sectional shape with a depth d of the groove MG of 4.0 μm and a width of the groove MG of 0.075 μm.Through these processing steps, a test piece of the resin layer 14 of Examples 1 to 3 was prepared, respectively.Further, test pieces of comparative resin layers 17 of Comparative Examples 1 to 3 were prepared in a similar manner to the resin layers 14 of Examples 1 to 3 except that the synthetic resins and the additives shown in Comparative Examples 1 to 3 of Table 1 were used as components of the comparative resin layers 17.As graphite, flake graphite having a degree of graphitization of 99% was used. As the clay, a clay having the structural formula Al 2 O 3-2 SiO 2 was used.Table 1 Table 1Example 1Remainder: Remainder:15,06,01,53,93,04,00,075K<d84MG processing was performed (form is normal)Example 2Remainder: Remainder:17,07,02,01,02,04,00,075129MG processing was performed (form is normal)Comparative Example 1Remainder: Remainder:15,07,02,05,05,0--K≥d48MG processing was not performed Table 2Table 2Example 3Remainder: Remainder:-6,0-2,0-4,00,075K<d-Shape is normalComparative Example 2Remainder: Remainder:-6,0-12,0-4,00,075K≥d-Shape is abnormalComparative Example 3Remainder: Remainder:-6,0-28,0-4,00,075-Shape is abnormal- Evaluation -- Seizure resistance -The seizure resistance was evaluated for the test pieces of Examples and the test piece of Comparative Example. The evaluation of seizure resistance was performed with a testing machine illustrated in FIG. 6.FIG. 6 is an explanatory view of a seizure resistance test. The groove MG side of the test piece corresponding to the resin layer 14 and the comparative resin layer 17 was placed to face the shaft member 30, and 45 mg of lubricating oil was applied to the surface of the groove MG side. Then, the shaft member 30 was rotated while applying a load, thereby evaluating the seizure resistance. The evaluation was carried out under the following conditions.Testing machine: a seizure testing machine (see FIG. 6 )- Load: 5 MPa- Rotational speed (circumferential speed): 2 m / s- Test temperature (ambient temperature): 40°Cmaterial of the shaft member 30: SCM 415 (Hv: 500 or higher)Surface roughness Ra of the shaft member 30: 0.15 μmLubricating oil: liquid paraffin (viscosity: 4.4×10 -3 Pa·s)- Lubrication method: application of lubricating oil; 45 mg- Oil distance: 100 μmdetermining seizure: the time (seconds) required from the start of the rotational drive of the shaft member 30 until the friction torque reaches 4.8 N·mThe shaft member 30 was rotated under the above-mentioned conditions, and the time (seconds) required from the start of the rotational drive of the shaft member 30 until the friction torque reached 4.8 N-m was measured as the elapsed time until seizure. The elapsed time until seizure is the time required from the start of the rotational drive of the shaft member 30 until the occurrence of seizure. The measurement results are shown in Table 1. It is understood from Table 1 that the longer the elapsed time to seizure, the higher the seizure resistance, i.e., the better the seizure resistance.Evaluation of improvement of seizure resistance based on the groove MG-As is clear from Table 1, all the test pieces of the examples having grooves MG had a longer elapsed time to seizure than the test piece of a comparative example having no grooves MG. Thus, evaluation results were obtained in which the test pieces of the resin layers 14 of the examples have higher seizure resistance than the test piece of the resin layer 17 of the comparative example.Determination of the processability of the groove shapeThe molding processability of the groove MG was evaluated for the test pieces of the examples and the test pieces of the comparative examples. The evaluation results are shown in Table 2.As shown in Table 2, when the Gr particle size was smaller than the depth of the groove MG, the rate of the shape defects of the groove shape was small (the shape is normal). Further, as shown in Table 2, when the Gr particle size was larger than the depth of the groove MG, the rate of the shape defects of the groove shape was large (the shape is abnormal).Specifically, for the test pieces of the examples and the test pieces of the comparative examples, the surface of the groove MG of each of the bearings 10 and the comparative bearings 1000 along the extending direction Z was scanned with a roughness meter (SE-3400 manufactured by Kosaka Laboratory Ltd.), and an enlarged curve of the surface shape along the extending direction Z of the groove MG was obtained. Then, for each of the test pieces of the examples and the test pieces of the comparative examples, the average value av of the depths d of the plurality of grooves MG included in the enlarged surface shape curve and the standard deviation σ of the depth d of the groove MG were calculated.Further, for each of the test pieces of the examples and the test pieces of the comparative examples, among the plurality of grooves MG included, a groove MG having a depth d within the range of the standard deviation σ×1 / 2 with respect to the average value av was determined to be normal, and a groove MG having a depth d outside the range was determined to be defective. Then, for each of the test pieces of the examples and the comparative examples, the shape of the groove MG was determined to be abnormal when the ratio of the grooves MG determined to be defective at the plurality of grooves MG was equal to or greater than 20%. Further, for each of the test pieces of the examples and the test pieces of the comparative examples, the shape of the groove MG was determined to be normal when the ratio of the grooves MG determined to be defective among the plurality of grooves MG included was less than 20%, and when the ratio was equal to or greater than 20%, the shape of the groove MG was determined to be abnormal. The results of the determination are shown in Table 1 and Table 2.As shown in Table 2, in all the test pieces of the examples, the shape of the groove MG was determined to be normal. On the other hand, in all the test pieces of the comparative examples, it was found that the shape of the groove MG is abnormal.The various materials and compositions thereof used in the above-described examples are merely examples, and the present invention is not limited thereto. The resin layer 14 according to the present invention may further contain inevitable impurities, etc. The specific structure of the bearing 10 is not limited to the structure shown in FIGS. 1A to 2 or the like.List of reference characters10 BEARING 12 BASE MATERIAL 14 RESIN LAYER 16 SYNTHETIC RESIN 16A PTFE PARTICLE 18 ADDITIVE 20 GRAPHITE 22 CLAY 40 COMPRESSORReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 5683571

[0002] JP 2018-193521 A

[0002]

Claims

A bearing comprising: a tubular base material; and a resin layer bonded to an inner circumferential surface of the base material, which is provided on a surface on a facing surface facing a shaft member accommodated so as to oppose the inner circumferential surface of the base material with a plurality of grooves extending along a direction intersecting an extending direction of the shaft member and containing a synthetic resin and an additive dispersed in the synthetic resin, wherein an average particle size of the additive is smaller than a depth of the plurality of grooves.The bearing of claim 1, wherein the additive includes at least one of graphite and clay.The bearing according to claim 2, wherein an average particle size of the graphite is equal to or more than 1.0 μm and less than 4.0 μm, an average particle size of the clay is equal to or more than 2.0 μm and less than 3.5 μm, and a depth of the groove is equal to or more than 4 μm and equal to or less than 7 μm.The bearing according to claim 1, wherein the synthetic resin contains PTFE particles.A compressor comprising the bearing of claim 1.

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