Abutment structure for component

Abstract

In the present invention, a fuel injection valve (10) comprises a first member (11) and a second member (40), each having an abutment surface that abuts against the other in the presence of hydrogen. At least one of the first member and the second member is a movable part, and the abutment surface of the first member is configured as a first abutment surface provided with a lubricating film of which at least a part is hydrogen-terminated. The abutment surface of the second member is configured as a second abutment surface provided with a catalyst part having the function of dissociating hydrogen into hydrogen radicals.

Description

Parts contact structure CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-062749, filed on April 9, 2024, the contents of which are incorporated herein by reference.

[0002] The disclosure in this specification relates to abutment structures for parts.

[0003] As a contact structure for components that contact two mutually abutting members, a configuration in which a solid lubricant is formed on the contact surfaces of the two members is known. For example, Patent Document 1 describes a configuration in which diamond-like carbon (hereinafter, DLC) is used as the solid lubricant. Patent Document 1 discloses a configuration in which DLC is formed on the contact surface of one of the two mutually abutting members, and the contact surface of the other member, a silicon substrate, is hydrogen-terminated. Patent Document 1 also discloses that hydrogen-terminating the surface of the silicon substrate reduces the coefficient of friction between the DLC and the silicon substrate compared to when the surface of the silicon substrate is not hydrogen-terminated.

[0004] Japanese Patent Application Laid-Open No. 2003-301840

[0005] Wear of the contact surfaces of two components that come into contact with each other can be suppressed by providing the contact surfaces with a solid lubricant. However, there is a concern that dangling bonds on one contact surface may bond with those on the other contact surface due to the exposure of dangling bonds on the contact surfaces to which the solid lubricant has been provided, thereby increasing the frictional force between the two contact surfaces.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a contact structure in a part that brings two members into contact with each other, which can suppress a decrease in solid lubricating function and protect the contact surfaces.

[0007] The present disclosure provides a device comprising a first member and a second member each having an abutment surface that abuts against each other in the presence of hydrogen, wherein at least one of the first member and the second member is a movable part, the abutment surface of the first member being configured as a first abutment surface provided with a lubricating film at least a portion of which is hydrogen-terminated, and the abutment surface of the second member being configured as a second abutment surface provided with a catalyst portion that has the function of dissociating hydrogen into hydrogen radicals.

[0008] When the contact structure described above is used in a hydrogen environment, dangling bonds may be exposed in the initially hydrogen-terminated lubricating film on the first contact surface due to contact. Even in this case, hydrogen in the environment where the contact structure is provided reacts with the catalyst portion on the second contact surface, generating hydrogen radicals through the catalytic function of the catalyst portion, which then bond with the dangling bonds in the lubricating film. In other words, hydrogen is continuously supplied to the lubricating film by the hydrogen in the environment, thereby restoring the hydrogen termination. This maintains the solid lubricating function of the lubricating film. As a result, the contact surface can be protected.

[0009] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a longitudinal cross-sectional view of a fuel injector, Fig. 2 is an explanatory diagram showing the relationship between a valve body and an injection hole, Fig. 3 is a diagram explaining the state of the contact surfaces when two components are in contact, Fig. 4 is a diagram explaining the reaction between a catalyst portion and hydrogen, Fig. 5 is a diagram explaining chemical reactions when the fuel injector is opened and closed, Fig. 6 is a longitudinal cross-sectional view of a fuel injector showing the positions of a lubricating film and a catalyst portion, Fig. 7 is a diagram explaining the state of the contact surfaces at the sliding portion, Fig. 8 is a longitudinal cross-sectional view of a valve body according to another embodiment, and Fig. 9 is a longitudinal cross-sectional view of a bearing according to another embodiment.

[0010] An embodiment of the component abutment structure according to the present disclosure will be described below with reference to the drawings. The abutment structure of this embodiment is applied to a hydrogen injector as a component. The hydrogen injector is applied to a direct-injection gas engine (internal combustion engine) that uses hydrogen gas, and the hydrogen gas is directly injected into the combustion chamber of the gas engine by the hydrogen injector. The hydrogen gas is a gas produced by vaporizing liquefied hydrogen stored in a hydrogen cylinder by reducing pressure, and corresponds to a hydrogen-containing gas. The gas engine is, for example, an automotive engine. In this embodiment, the fuel injection system equipped with a fuel injection valve as a hydrogen injector is a so-called low-pressure direct injection system in which hydrogen gas compressed to about several MPa is injected from the fuel injection valve into the combustion chamber.

[0011] The configuration of a fuel injection valve 10 will be described using Figure 1. Figure 1 shows a longitudinal cross-sectional structure of a main portion of the fuel injection valve 10. In the following description, the direction in which the central axis of the fuel injection valve 10 extends (i.e., the vertical direction in Figure 1) is referred to as the axial direction, the direction extending radially from the axis is referred to as the radial direction, and the direction extending circumferentially around the axis is referred to as the circumferential direction. In Figure 1, the upper side is the base end side (upstream side) of the fuel injection valve 10, and the lower side is the tip side (downstream side).

[0012] The fuel injection valve 10 includes a cylindrical housing 11 having a fuel passage 12 therein. The housing 11 is made of a magnetic material, and a non-magnetic portion 11a made of a non-magnetic material is provided in the axial middle portion. The housing 11 has a cylindrical hollow portion, and the fuel passage 12 is formed in the hollow portion and extends in the axial direction. Hydrogen gas is supplied to the fuel passage 12 from the axial base end side (upper side in the figure). In the fuel injection valve 10, the fuel passage 12 corresponds to the "gas passage," and the housing 11 corresponds to the "main body."

[0013] The housing 11 has a cylindrical portion 13 and an end plate portion 14 provided at the axial tip of the cylindrical portion 13. The end plate portion 14 is provided with an injection hole 14a for injecting hydrogen gas into the engine combustion chamber. The injection hole 14a is provided so as to be surrounded by a valve seat 15 provided in the center of the end plate portion 14. The fuel injection valve 10 is assembled to a gas engine with the end plate portion 14 exposed to the combustion chamber. Note that the end plate portion 14 does not necessarily have to be flat, extending perpendicular to the axial direction as shown, and may be, for example, conical in shape with a convex tip.

[0014] A fixed core 20 made of a magnetic material is fixed within the housing 11. The fixed core 20 has a plurality of communication passages 21 that connect the upstream side and the downstream side, and within the fuel passage 12, hydrogen gas can flow from the upstream side to the downstream side of the fixed core 20 via the communication passages 21.

[0015] A movable core 30 made of a magnetic material is disposed within the fuel passage 12 on the upstream side of the fixed core 20, in other words, on the opposite side of the injection hole 14a across the fixed core 20 in the axial direction.

[0016] The movable core 30 is capable of reciprocating in the axial direction along the inner circumferential surface of the cylindrical portion 13. The movable core 30 has a plurality of communication passages 31 that communicate with each other in the axial direction. The communication passages 31 are preferably provided at positions that are continuous with the communication passages 21 of the fixed core 20 in the axial direction.

[0017] The housing 11 is provided with a position restricting portion 16 that restricts the axial position of the movable core 30. The movable core 30 is movable in the axial direction between the position restricting portion 16 and the fixed core 20. The downstream end face of the movable core 30 and the upstream end face of the fixed core 20 face each other and are parallel to each other. The movable core 30 corresponds to the "operating portion."

[0018] A valve element 40 that opens and closes the injection hole 14a is disposed downstream of the movable core 30. The valve element 40 is needle-shaped and is inserted into the insertion hole 22 of the fixed core 20. The valve element 40 is an outward-opening valve that opens when moved outside the housing.

[0019] The valve element 40 has a tip valve portion 41 provided at the axial tip, and a shaft portion 42 extending from the tip valve portion 41. In the valve element 40, the tip valve portion 41 is conical, and the shaft portion 42 is provided integrally with the conical apex of the tip valve portion 41. The axial upper end of the shaft portion 42 abuts against the movable core 30. In addition, a flange portion 43 is provided at the end of the shaft portion 42 opposite the tip valve portion 41. A spring 44 made of a compression coil spring is provided between the flange portion 43 and the fixed core 20.

[0020] The valve element 40 is inserted into the injection hole 14a, and the tip valve portion 41 closes the injection hole 14a from outside the housing. In this case, the injection hole 14a is opened by moving the tip valve portion 41 away from the end plate portion 14. The valve element 40 is preferably made of a metal material, a non-metal material, or another non-elastomer material that has excellent heat resistance. The valve element 40 has an outward opening valve structure, which prevents flames and combustion pressure in the engine combustion chamber from flowing into the injection valve.

[0021] A solenoid coil 17 is provided in the housing 11. When the solenoid coil 17 is energized by a current-carrying circuit (not shown), the movable core 30 is displaced toward the fixed core 20. In this case, as the movable core 30 is displaced, the valve element 40 moves toward the valve-opening side (downward in the figure) against the biasing force of the spring 44.

[0022] The structures of the tip valve portion 41 and the valve seat 15 that abuts against the tip valve portion 41 will be described in detail. The valve seat 15 has a tapered surface that is inclined with respect to the axial direction. In the tip valve portion 41, the side surface of the conical portion is the opposing seat portion 45 that faces the valve seat 15. In the closed valve state, the valve seat 15 and the opposing seat portion 45 abut against each other in a state of circumferential line contact or surface contact. The opposing seat portion 45 corresponds to the "opposing surface."

[0023] As shown in Figure 2, the valve seat 15 on the housing 11 side and the opposing seat portion 45 on the tip valve portion 41 side abut against each other. A lubricating film 18 is formed on the valve seat 15, and a catalyst portion 47 is formed on the opposing seat portion 45. The lubricating film 18 is formed from a solid lubricant, at least a portion of which is hydrogen-terminated. A carbon-based material, specifically diamond-like carbon, is preferably used as the solid lubricant in the lubricating film 18. The lubricating film 18 may contain elements other than carbon and hydrogen.

[0024] The catalyst portion 47 is formed of a catalyst that has the function of dissociating hydrogen into hydrogen radicals. A metal oxide such as zirconium oxide or cerium oxide is used for the catalyst portion 47. However, a noble metal such as platinum or palladium may also be used for the catalyst portion 47. The catalyst portion 47 is provided in the form of a film or layer on the counter seat portion 45. However, the catalyst portion 47 may also be provided in the form of particles, specifically, nanoparticles, on the counter seat portion 45.

[0025] When the fuel injection valve 10 is attached to a gas engine, the valve body 40 of the fuel injection valve 10 is heated by heat received from the combustion chamber, which is a heat source. In this case, the catalyst portion 47 of the seat portion 45 is activated by the heat received from the combustion chamber during engine operation.

[0026] At the contact portion between the valve seat 15 and the tip valve portion 41, the housing 11 corresponds to the "first member," and the valve seat 15 and the lubricating film 18 form a "first contact surface." The valve body 40 corresponds to the "second member," and the seat-facing portion 45 and the catalyst portion 47 form a "second contact surface."

[0027] The lubricating film 18 and the catalyst portion 47 preferably have different hardnesses. Specifically, the lubricating film 18 is preferably softer than the catalyst portion 47, and the state of chemical bonding of the lubricating film 18 is preferably changed when the lubricating film 18 and the catalyst portion 47 come into contact with each other.

[0028] In the valve body 40, in addition to the catalyst portion 47 being provided in the facing seat portion 45 of the tip valve portion 41, it is preferable that a catalyst portion 48 be provided in the stem portion 42. The catalyst portion 48 in the stem portion 42 may have the same configuration as the catalyst portion 47 in the facing seat portion 45, or may have a different configuration. For example, it is preferable that the catalyst portion 47 in the facing seat portion 45 is made of a metal oxide such as zirconium oxide or cerium oxide, while the catalyst portion 48 in the stem portion 42 is made of a precious metal such as platinum or palladium. It is also preferable that the catalyst portion 47 is provided in the facing seat portion 45 in the form of a film or layer, while the catalyst portion 48 is provided in the form of particles in the stem portion 42.

[0029] 2(a) and 2(b), in the fuel injection valve 10, as the valve body 40 opens and closes, the catalyst portion 47 on the tip valve portion 41 side repeatedly comes into contact with the lubricating film 18 on the valve seat 15 side (see FIG. 2(a)), and then moves away from the lubricating film 18 (see FIG. 2(b)). In this case, the contact between the catalyst portion 47 and the lubricating film 18 may expose dangling bonds on the contact surface.

[0030] 3A shows, as a comparative example, a movable member 60 and a fixed member 70 in which dangling bonds are exposed at the interface between the members and the space. As shown in FIG. 3B, when the movable member 60 and the fixed member 70 come into contact with each other, the dangling bonds bond together. In this case, the chemical bonding force between the contacting surfaces is constantly acting on each other, which raises concerns about an increase in the frictional force between the contacting surfaces.

[0031] In this embodiment, as shown in FIG. 4 , hydrogen derived from the fuel is present around the valve body 40. The hydrogen is dissociated in the valve body 40 by the catalytic function of the catalyst portion 47, generating hydrogen radicals. The generated hydrogen radicals bond with exposed dangling bonds in the lubricating film 18. This reduces the number of exposed dangling bonds in the lubricating film 18, and the lubricating film 18 is hydrogen-terminated, thereby reducing friction between the lubricating film 18 and the catalyst portion 47.

[0032] Next, a detailed description will be given of the mechanism by which the lubricating film 18 is hydrogen-terminated. Figures 5(a) to 5(d) are diagrams for explaining the chemical reactions that occur when the fuel injection valve 10 is opened or closed.

[0033] FIG. 5A shows the fuel injection valve 10 in an open state. Note that hydrogen atoms fixed to the lubricating film 18 are not shown in FIG. 5A . Here, hydrogen is present around the valve body 40. As shown in FIG. 5B , when the fuel injection valve 10 is closed, the tip valve portion 41 abuts against the valve seat 15. In this case, as shown in FIG. 5C , the catalyst portion 47 dissociates hydrogen due to thermal energy received from the engine combustion chamber and kinetic energy when the tip valve portion 41 abuts, generating hydrogen radicals. Furthermore, when the engine is operating, the stem portion 42 of the valve body 40 is heated to a high temperature along with the tip valve portion 41, and hydrogen radicals are also generated in the catalyst portion 48 of the stem portion 42 due to hydrogen dissociation.

[0034] As shown in FIG. 5D, the generated hydrogen radicals bond to the exposed dangling bonds of the lubricating film 18, thereby hydrogen-terminating the lubricating film 18.

[0035] In the fuel injection valve 10, a lubricating film 18 is formed on the valve seat 15 on the housing 11 side, and a catalyst portion 47 is provided on the opposing seat portion 45 on the valve body 40 side. Therefore, even if dangling bonds are exposed in the lubricating film 18 due to the contact between the valve seat 15 and the tip valve portion 41, hydrogen radicals generated by the catalytic function of the catalyst portion 47 bond with the dangling bonds. This maintains the solid lubricating function of the lubricating film 18. As a result, the contact portion of the fuel injection valve 10 can be protected.

[0036] The catalyst portion 47 functions to dissociate hydrogen into hydrogen radicals under a predetermined high temperature condition. In this regard, in the fuel injection valve 10 configured as described above, the tip valve portion 41 provided with the catalyst portion 47 becomes hot due to heat received from the engine combustion chamber, so that the frequency with which exposed dangling bonds of the lubricating film 18 bond with hydrogen radicals can be increased.

[0037] By forming the catalyst portion 48 on the shaft portion 42, hydrogen radicals are generated upstream of the tip valve portion 41 due to the catalytic function of the catalyst portion 48. The generated hydrogen radicals move to the contact portion between the tip valve portion 41 and the valve seat 15, and hydrogen-terminate the lubricating film 18 formed on the valve seat 15.

[0038] In the valve body 40, in addition to the catalyst portion 47 in the tip valve portion 41, a catalyst portion 48 is provided in the stem portion 42, which allows hydrogen gas to come into contact with the catalyst upstream of the lubricating film 18 on the valve seat 15. This increases the amount of hydrogen radicals generated by the catalytic function, and when dangling bonds are exposed in the lubricating film 18, the dangling bonds and hydrogen radicals bond more frequently.

[0039] 6, in the fuel injection valve 10, in addition to the contact portion between the valve seat 15 and the counter seat portion 45, a lubricating film and a catalyst portion are provided at the contact portion between the cylindrical portion 13 of the housing 11 and the movable core 30. In this case, the inner peripheral surface 13a of the cylindrical portion 13 and the outer peripheral surface 30a of the movable core 30 are in slidable contact with each other, and the movable core 30 slides relative to the cylindrical portion 13 when the valve element 40 is opened or closed.

[0040] In this configuration, a lubricating film 32 is formed on the outer peripheral surface 30a of the movable core 30, and a catalyst portion 19 is formed on the inner peripheral surface 13a of the cylindrical portion 13. The outer peripheral surface 30a of the movable core 30 and the lubricating film 32 form a "first contact surface," and the inner peripheral surface 13a of the cylindrical portion 13 and the catalyst portion 19 form a "second contact surface."

[0041] The lubricating film 32 is formed of a solid lubricant at least a portion of which is hydrogen-terminated, similar to the lubricating film 18 described above, and preferably uses a carbon-based material as the solid lubricant. Similarly to the catalyst portion 47 described above, the catalyst portion 19 is formed of a catalyst that has the function of dissociating hydrogen into hydrogen radicals. The configuration of the catalyst portion 19 may be the same as that of the catalyst portion 47. The catalyst portion 19 is preferably provided on a portion of the inner circumferential surface 13a of the cylindrical portion 13 that abuts against the outer circumferential surface 30a of the movable core 30.

[0042] The lubricating film 32 and the catalyst portion 19 preferably have different hardnesses. Specifically, the lubricating film 32 is preferably softer than the catalyst portion 19, and the state of chemical bonding of the lubricating film 32 is preferably changed when the lubricating film 32 and the catalyst portion 19 come into contact with each other.

[0043] When the fuel injection valve 10 opens and closes, the movable core 30 slides with its outer peripheral surface 30a in contact with the inner peripheral surface 13a of the cylindrical portion 13. This sliding movement may expose dangling bonds at the contact surface. Hydrogen flowing from the fuel passage 12 may be present in the minute clearance between the cylindrical portion 13 and the movable core 30. Therefore, the catalyst portion 19 dissociates hydrogen through its catalytic function to generate hydrogen radicals. The generated hydrogen radicals bond with exposed dangling bonds in the lubricating film 32. This reduces the number of exposed dangling bonds in the lubricating film 32. That is, as shown in FIG. 7 , the lubricating film 32 is hydrogen-terminated, reducing friction between the lubricating film 32 and the catalyst portion 19 compared to when dangling bonds remain exposed in the lubricating film 32. This protects the sliding surfaces of the movable core 30 and the cylindrical portion 13. 7, the white circles representing the lubricating film 32 represent atoms that make up the lubricating film 32. The black circles representing the catalyst portions 19 represent atoms that make up the catalyst portions 19.

[0044] In the fuel injection valve 10, the catalyst portion provided at the contact portion between the valve seat 15 and the opposing seat portion 45 (catalyst portion 47 on the opposing seat portion 45 side) may have a different configuration from the catalyst portion provided at the contact portion between the cylindrical portion 13 of the housing 11 and the movable core 30 (catalyst portion 19 on the cylindrical portion 13 side). Note that the catalyst portion 47 corresponds to the "first catalyst portion," and the catalyst portion 19 corresponds to the "second catalyst portion."

[0045] In other words, the contact portion between the valve seat 15 and the opposing seat portion 45 is a portion where the valve seat 15 and the opposing seat portion 45 come into contact as the opposing seat portion 45 butts against the valve seat 15. In contrast, the contact portion between the cylindrical portion 13 of the housing 11 and the movable core 30 is a portion where the cylindrical portion 13 and the movable core 30 come into contact in a sliding state. Since the load and surface pressure on the catalyst portion differ at each of these contact portions, it is preferable that the catalyst portion be configured taking these differences into consideration.

[0046] When the valve body 40 opens and closes the injection hole 14a, a load is applied to the catalyst portion 47 provided in the tip valve portion 41 in the axial direction of the fuel injection valve 10. Therefore, the load applied to the catalyst portion 47 is greater than the load applied to the catalyst portion 19. Here, it is preferable that the thickness of the catalyst portion 47 is greater than the thickness of the catalyst portion 19. In this case, by providing a thick catalyst portion in a portion where a greater load is applied, the strength of the catalyst portion can be increased.

[0047] The catalyst portion 47 is preferably a film-like or layer-like metal oxide having high strength, and the catalyst portion 19 is preferably a particulate precious metal having lower strength than the film-like or layer-like metal oxide. By providing a catalyst portion made of a strong material in a portion that is subjected to a greater load, the strength of the catalyst portion can be increased.

[0048] (Other Embodiments) The above embodiment may be modified as follows, for example.

[0049] In the above embodiment, the contact structure of the present disclosure is applied to an injection valve that injects hydrogen gas as a hydrogen-containing gas. However, this may be modified to apply the contact structure of the present disclosure to an injection valve that injects other hydrogen-containing gases, such as compressed natural gas (CNG) or liquefied natural gas (LNG).

[0050] The fuel injection valve 10 may be configured such that the movable core 30 and the valve element 40 are integral with each other. In this case, the fuel injection valve 10 is configured such that the lubricating film 32 is provided on the outer circumferential surface of the valve element 40 that abuts against the inner circumferential surface 13 a of the cylindrical portion 13.

[0051] In the above embodiment, the component structure of the present disclosure is applied to a hydrogen injection valve that directly injects hydrogen gas into the combustion chamber of a gas engine. However, this may be modified to apply the component structure of the present disclosure to an injection valve for port injection.

[0052] In the above embodiment, the valve body 40 has an outward opening structure. However, this may be changed so that the valve body 40 has an inward opening structure.

[0053] In the above embodiment, the seat 45 on which the catalyst portion 47 is formed may have an uneven shape. For example, as shown in FIG. 8 , a recess 46 extending in the circumferential direction is formed in the seat 45 of the tip valve portion 41. The recess 46 may be provided as multiple axially arranged windings or in a spiral shape on the seat 45, which forms a conical side surface. The depth of the recess 46 may be on the order of micrometers. The amount of hydrogen radicals generated by the reaction between hydrogen and the catalyst portion 47 increases as the surface area of ​​the catalyst portion 47 increases. Here, by having the contact surface on which the catalyst portion 47 is formed have an uneven shape, the amount of dissociated hydrogen increases, thereby increasing the amount of hydrogen radicals supplied to the lubricating film 18. This increases the frequency with which dangling bonds in the lubricating film 18 bond with hydrogen radicals when they are exposed.

[0054] The valve body 40 may be made of a porous metal material, and recesses may be formed on the surface of the valve body by the pores of the porous metal material.

[0055] In the fuel injection valve 10 configured as described above, in addition to the seating portion 45 of the tip valve portion 41, the catalyst portion 48 is provided on the stem portion 42 of the valve body 40, but this may be modified so that the catalyst portion 48 is not provided on the stem portion 42. Also, in the fuel injection valve 10, in addition to the abutting portion between the valve seat 15 and the seating portion 45, a lubricating film and a catalyst portion are provided on the abutting portion between the cylindrical portion 13 of the housing 11 and the movable core 30, but this may be modified so that the lubricating film and a catalyst portion are not provided on the abutting portion between the cylindrical portion 13 and the movable core 30.

[0056] In Figure 6, instead of the configuration in which a lubricating film 32 is provided on the outer peripheral surface 30a of the movable core 30 and a catalyst portion 19 is provided on the inner peripheral surface 13a of the cylindrical portion 13 as the abutment structure between the movable core 30 and the cylindrical portion 13, a configuration in which a catalyst portion is provided on the outer peripheral surface 30a of the movable core 30 and a lubricating film is provided on the inner peripheral surface 13a of the cylindrical portion 13 may be used.

[0057] The hydrogen present around the abutment structure of the present disclosure may be in a gaseous or liquid state.

[0058] The catalysts forming the catalyst portions 47, 48, and 19 are not limited to metal oxides and precious metals. Specifically, they may be catalysts containing transition elements other than precious metals that have the function of dissociating hydrogen into hydrogen radicals.

[0059] The component abutment structure disclosed herein can be applied to abutting parts that repeatedly come into and out of contact with each other, sliding parts that slide against each other, and rolling parts. Examples of applications of rolling parts include bearings and engine valve trains. Specifically, when the abutment structure disclosed herein is applied to a bearing, it is conceivable to form a lubricating film on one of the bearing's rolling elements and the member with which the rolling elements abut, and provide a catalyst part on the other.

[0060] 9 is a cross-sectional view of the bearing 80 taken along the rotation axis. The bearing 80 includes an outer ring member 81, an inner ring member 82, and a plurality of rolling elements 83 (specifically, cylindrical rollers) arranged between the outer ring member 81 and the inner ring member 82. The rolling elements 83 are supported so as to be rotatable relative to the outer ring member 81 and the inner ring member 82, with their cylindrical side surfaces in contact with the outer ring member 81 and the inner ring member 82. A shaft body 90 rotatably supported by the bearing 80 is fixed to the inner ring member 82. When the shaft body 90 rotates, the inner ring member 82 rotates integrally with the shaft body 90, and the rolling elements 83 rotate in conjunction with the rotation of the inner ring member 82.

[0061] In this configuration, a catalyst portion 85 is formed on the outer peripheral surface 83a of the rolling element 83. Furthermore, lubricating films 86, 87 are formed on opposing surfaces 81a, 82a of the outer ring member 81 and the inner ring member 82 that face the outer peripheral surface 83a of the rolling element 83. Similar to the lubricating film 18 described above, the lubricating films 86, 87 are formed from a solid lubricant that is at least partially hydrogen-terminated, and it is preferable that a carbon-based material be used as the solid lubricant. Furthermore, similar to the catalyst portion 47 described above, the catalyst portion 85 is formed from a catalyst that has the function of dissociating hydrogen into hydrogen radicals. The configuration of the catalyst portion 85 may be the same as that of the catalyst portion 47.

[0062] 9, instead of the configuration in which the catalyst portion 85 is provided on the rolling element 83 side and the lubricating films 86, 87 are provided on the outer ring member 81 and the inner ring member 82 side, a configuration in which a lubricating film is provided on the rolling element 83 side and catalyst portions are provided on the outer ring member 81 and the inner ring member 82 side may be used. In a configuration in which catalyst portions are provided on the outer ring member 81 and the inner ring member 82 side, it is preferable that at least one of the outer ring member 81 and the inner ring member 82 is heated by receiving heat from a heat source.

[0063] Furthermore, when the abutment structure of the present disclosure is applied to an engine valve mechanism, it is conceivable to form a lubricating film on one of the cam of the camshaft and the lifter that opens and closes the intake valve or exhaust valve, and to provide a catalyst part on the other.

[0064] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A component abutment structure comprising a first member and a second member each having an abutment surface that abuts against each other in the presence of hydrogen, at least one of the first member and the second member being a movable part, the abutment surface of the first member being configured as a first abutment surface provided with a lubricating film at least a portion of which is hydrogen-terminated, and the abutment surface of the second member being configured as a second abutment surface provided with a catalyst portion that has the function of dissociating hydrogen into hydrogen radicals. [Configuration 2] The component abutment structure according to Configuration 1, wherein at least the second member of the first member and the second member is a member that is heated by receiving heat from a heat source. [Configuration 3] The component abutment structure according to Configuration 1 or 2, wherein the second abutment surface has an uneven shape. [Configuration 4] The abutment structure for a part according to any one of Configurations 1 to 3, which is applied to a hydrogen injector (10) that injects hydrogen-containing gas, the hydrogen injector having: a main body (11) having a gas passage (12) through which the hydrogen-containing gas passes and an injection hole (14a) through which the hydrogen-containing gas in the gas passage is injected; and a valve body (40) that opens and closes the injection hole, the valve body having a tip valve portion (41) at an axial tip of the hydrogen injector, the tip valve portion abutting a valve seat (15) provided in the main body so as to surround the injection hole, the valve seat being the first abutment surface, and an opposing surface (45) of the tip valve portion that faces the valve seat and abuts against the valve seat being the second abutment surface. [Configuration 5] The abutment structure for a part according to Configuration 4, [Configuration 6] The hydrogen injection valve has an abutment structure for parts as described in Configuration 4 or 5, in which the valve body or an operating part (30) that operates together with the valve body is slidable relative to the main body, and one of the sliding surfaces between the valve body or the operating part and the main body is the first abutment surface, and the other is the second abutment surface.[Configuration 7] The abutment structure for parts according to Configuration 6, wherein the catalyst portion provided on the tip valve portion is a first catalyst portion (47), the catalyst portion provided on the sliding surface is a second catalyst portion (19), and the thickness of the first catalyst portion is greater than the thickness of the second catalyst portion. [Configuration 8] The abutment structure for parts according to Configuration 6 or 7, wherein the catalyst portion provided on the tip valve portion is a first catalyst portion (47), the catalyst portion provided on the sliding surface is a second catalyst portion (19), and the first catalyst portion is made of a metal oxide, and the second catalyst portion is made of a precious metal.

[0065] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A contact structure for parts comprising a first member and a second member each having a contact surface that contacts each other in the presence of hydrogen, wherein at least one of the first member and the second member is a movable part, the contact surface of the first member being configured as a first contact surface provided with a lubricating film at least a portion of which is hydrogen-terminated, and the contact surface of the second member being configured as a second contact surface provided with a catalyst portion that has the function of dissociating hydrogen into hydrogen radicals.

2. The component contact structure according to claim 1, wherein at least the second member of the first and second members is a member that is heated by receiving heat from a heat source.

3. The component abutment structure according to claim 1, wherein the second abutment surface has an uneven shape.

4. The abutment structure for a part described in claim 1, which is applied to a hydrogen injection valve (10) that injects hydrogen-containing gas, the hydrogen injection valve having: a main body (11) having a gas passage (12) through which hydrogen-containing gas passes and an injection hole (14a) that injects the hydrogen-containing gas in the gas passage; and a valve body (40) that opens and closes the injection hole, the valve body having a tip valve portion (41) at the axial tip of the hydrogen injection valve, the tip valve portion abutting against a valve seat (15) provided in the main body so as to surround the injection hole, the valve seat being the first abutment surface, and an opposing surface (45) of the tip valve portion that faces the valve seat and abuts against the valve seat being the second abutment surface.

5. The component abutment structure according to claim 4, wherein the catalyst portion is provided on the valve body not only on the opposing surface but also upstream of the tip valve portion in the flow direction of hydrogen gas in the gas passage.

6. The hydrogen injection valve has a contact structure for parts as described in claim 4 or 5, wherein the valve body or an operating part (30) that operates together with the valve body is slidable relative to the main body, and one of the sliding surfaces between the valve body or the operating part and the main body is the first contact surface, and the other is the second contact surface.

7. The contact structure of a part described in claim 6, wherein the catalyst portion provided on the tip valve portion is a first catalyst portion (47), the catalyst portion provided on the sliding surface is a second catalyst portion (19), and the thickness of the first catalyst portion is greater than the thickness of the second catalyst portion.

8. The contact structure of a part described in claim 6, wherein the catalyst portion provided on the tip valve portion is a first catalyst portion (47), the catalyst portion provided on the sliding surface is a second catalyst portion (19), the first catalyst portion is made of a metal oxide, and the second catalyst portion is made of a precious metal.

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