Slide bearing device

Abstract

To provide a slide bearing device which can secure exact sealing performance, and is high in durability.SOLUTION: A slide bearing device has a first member 2 and a second member 3 which relatively rotate around the same axis, and a sealing device 4 for sealing a bearing space. An α+β type or an α-type titanium-alloy made slide face 6 in which a primary α crystal gain and a secondary α crystal gain are contained is formed at least at either of the first member 2 or the second member 3, an oxygen diffusion layer 7 whose oxygen concentration is reduced according to a depth from a surface is formed at the slide face 6, and the first member 2 or the second member 3 which opposes the slide face 6 slide-contacts with the slide face 6 via a solid lubrication material 5 having self-lubricity. The sealing device 4 has a ring-shaped case 8 arranged at either of the first member 2 or the second member 3, a ring-shaped seal body 9 arranged at the case 8, and contacting with the other member of the first member 2 or the second member 3, and an energization member 10 for energizing the seal body 9 to the other member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sliding bearing device. [Background technology]

[0002] In typical bearings, a rubber seal is provided between the inner and outer rings to prevent foreign matter from entering the bearing space. However, rubber loses elasticity in low and high temperature environments due to hardening, embrittlement, deterioration, etc. caused by changes in its molecular structure, making it difficult to use in harsh temperature environments such as space, where temperatures range from extremely low to high temperatures. For example, rubber seals may not be able to reliably prevent the intrusion of hard foreign matter such as sand (regolith) into the bearing in the lunar environment.

[0003] Therefore, for example, Patent Document 1 listed below proposes a bearing equipped with a composite seal consisting of a fiber seal placed on the inside in the axial direction as a sealing member (seal body) that is less susceptible to the effects of temperature changes, and a resin seal placed on the outside in the axial direction (see paragraphs 0045-0046, Figure 8, etc. of this document). This sealing member comes into contact with the outer circumferential surface of the inner ring by the biasing force of the radial constraint member, and is held in a predetermined position in the axial direction by the elastic force of the straight portions and elastically curved portions of two fixed plates that axially sandwich the sealing body.

[0004] The resin seal is formed with an air vent hole through which air in the bearing space can escape, and the textile seal prevents foreign matter from entering the bearing space through the air vent hole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-168068 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the configuration disclosed in Patent Document 1, there is a risk of foreign matter entering the bearing space from outside the bearing through the air vent holes formed in the resin seal and through gaps in the fibers of the fabric seal, raising concerns about sealing. In addition, because the seal member is held in place by the elastic force of the two fixed plates, when the internal pressure of the bearing space changes significantly, the fixed plates deform in the axial direction against the elastic force, compromising the holding power of the seal member, which may result in a decrease in sealing ability or damage.

[0007] In addition, in the configuration according to Patent Document 1, stainless steel is used as the material for the outer and inner rings (see paragraph 0028 of this document), but stainless steel has a relatively high specific gravity and may cause problems when applied to the space field. Changing the material of the inner and outer rings from stainless steel to a metal with a relatively low specific gravity such as a titanium alloy can contribute to improving launch capabilities and reducing costs, but compared to stainless steel, general titanium alloys are not sufficient in terms of hardness, wear resistance, fatigue strength, etc., and there are issues with durability.

[0008] Therefore, an object of the present invention is to provide a sliding bearing device that ensures reliable sealing and is highly durable. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides: A sliding bearing device comprising: a first member; a second member arranged radially outwardly of the first member and coaxially rotating relative to the first member; and a sealing device provided between the first member and the second member and sealing a bearing space formed between the two members, At least one of the first member and the second member is provided with a sliding surface made of an α+β type or α type titanium alloy containing primary α crystal grains and secondary α crystal grains, the sliding surface is provided with an oxygen diffusion layer in which the oxygen concentration decreases depending on the depth from the surface, and the first member or the second member facing the sliding surface is in sliding contact with the sliding surface via a solid lubricant having self-lubricating properties that is provided integrally with the member, a ring-shaped case provided on one of the first member and the second member; a ring-shaped seal member provided in the case and in contact with the other of the first member and the second member; a biasing member that biases the seal body against the other member; The present invention provides a plain bearing device having the above features.

[0010] In this way, the seal body provided in the case is securely held, and high sealing performance is ensured. In addition, the seal body of the sealing device expands and contracts in diameter, allowing air in the bearing space to escape. Meanwhile, as the internal pressure of the bearing space decreases, the seal body expands and contracts in diameter due to the biasing force of the biasing member, and comes into contact with the first member or the second member, ensuring reliable sealing. In addition, by providing a sliding surface made of an α+β type or α type titanium alloy and providing an oxygen diffusion layer on this sliding surface, a weight reduction suitable for use in the space field and the like can be achieved, and sufficient wear resistance and fatigue strength to withstand use in harsh environments can be ensured, thereby improving durability.

[0011] The above-mentioned sliding bearing device can be configured to further include a biasing member that biases the seal body in a direction perpendicular to the direction in which the seal body protrudes. In this way, the seal body is positioned in the axial direction, thereby further improving the sealing performance of the seal body.

[0012] In all of the above sliding bearing devices, a plurality of the seal bodies are arranged in radial concentric contact, a joint is formed by cutting a portion of the circumferential direction of each of the seal bodies, and both ends of the joint slide in the circumferential direction to allow the seal body to expand and contract in diameter, and the circumferential positions of the respective joints of the plurality of the seal bodies can be arranged so as to be offset. In this way, by arranging the circumferential positions of the respective joints of the plurality of the seal bodies so as to be offset, the seal bodies can easily expand and contract in diameter in response to changes in the internal pressure of the bearing space, and it is also possible to prevent foreign matter from entering the bearing space through the joints.

[0013] In a configuration in which a plurality of seal bodies are arranged concentrically in the radial direction, both ends of the gap formed in each of the seal bodies can be configured to slide on mating surfaces having a normal in the axial direction, which can further prevent foreign matter from entering the bearing space through the gaps of the seal bodies arranged in the radial direction.

[0014] In all of the above sliding bearing devices, a plurality of the seal bodies are arranged in concentric contact in the axial direction, a joint is formed by cutting a portion of the circumferential direction of each of the seal bodies, and both ends of the joint slide in the circumferential direction to allow the seal body to expand and contract in diameter, and the circumferential positions of the respective joints of the plurality of the seal bodies can be arranged so as to be offset. In this way, by arranging the circumferential positions of the respective joints of the plurality of the seal bodies so as to be offset, the seal bodies can easily expand and contract in diameter in response to changes in the internal pressure of the bearing space, and it is also possible to prevent foreign matter from entering the bearing space through the joints.

[0015] In a configuration in which a plurality of seal bodies are arranged concentrically in the axial direction, both ends of the gap formed in each of the seal bodies can be configured to slide on mating surfaces having a normal in the radial direction, which can further prevent foreign matter from entering the bearing space through the gaps of the seal bodies arranged in the axial direction.

[0016] All of the above-mentioned plain bearing devices can be employed in a sleeve-type plain bearing structure.

[0017] All of the above sliding bearing devices can be used in aerospace related equipment. Effect of the Invention

[0018] The sliding bearing device of the present invention comprises a ring-shaped case provided on one of the first member or the second member, a ring-shaped sealing body provided on the case and in contact with the other of the first member or the second member, and a biasing member that biases the sealing body against the other member, and the sliding surfaces of the members are provided with sliding surfaces made of an α+β type or α type titanium alloy, and the sliding surfaces are provided with an oxygen diffusion layer in which the oxygen concentration decreases with depth from the surface, ensuring reliable sealing performance and high durability. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing one embodiment of a sliding bearing device according to the present invention (sleeve-shaped sliding bearing structure). [Diagram 2] FIG. 2 is a cross-sectional view showing a main portion of the sliding bearing device shown in FIG. [Diagram 3] Cross-sectional view taken along line III-III in Figure 2 [Figure 4] FIG. 2 is a perspective view of a seal body used in the sliding bearing device shown in FIG. [Diagram 5] FIG. 2 is a cross-sectional view showing a modified example of the sliding bearing device shown in FIG. [Figure 6] Cross-sectional view taken along line VI-VI in Figure 5 [Figure 7] FIG. 6 is a perspective view of a seal body used in the sliding bearing device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] One embodiment of a sliding bearing device 1 (hereinafter referred to as bearing 1) according to the present invention will be described with reference to Figures 1 to 4. In the following description, the direction along the rotation axis of the inner and outer rings will be referred to as the axial direction, the direction perpendicular to the rotation axis will be referred to as the radial direction, and the direction along the arc centered on the rotation axis will be referred to as the circumferential direction.

[0021] 1, the main components of this bearing 1 are a first member 2 (hereinafter referred to as the inner ring 2 and given the same reference number as the first member 2), a second member 3 (hereinafter referred to as the outer ring 3 and given the same reference number as the second member 3) that is provided on the outer periphery of the inner ring 2 and rotates coaxially relative to the inner ring 2, and a sealing device 4 that is provided between the inner ring 2 and the outer ring 3 and seals the bearing space formed between the inner and outer rings 2, 3. The bearing 1 according to this embodiment has a sleeve-shaped sliding bearing structure in which the inner ring 2 and the outer ring 3 rotate relatively about the axis via a solid lubricant 5 (liner) having self-lubricating properties that is provided between the inner and outer rings 2, 3.

[0022] Both axial ends of the inner ring 2 and the outer ring 3 are formed with recesses for mounting the sealing device 4. A solid lubricant 5 is provided integrally with the outer ring 3 and the sealing device 4 on the surface of the outer ring 3 facing the inner ring 2 and on the axial surface of the sealing device 4 facing the inner ring 2. The inner ring 2 is made of an α+β or α type titanium alloy containing primary α crystal grains and secondary α crystal grains, and is provided with a sliding surface 6 facing the outer ring 3. The sliding surface 6 is provided with an oxygen diffusion layer 7 in which the oxygen concentration decreases with depth from the surface. The outer ring 3 is in sliding contact with the sliding surface 6 via the solid lubricant 5.

[0023] As shown enlarged in FIG. 2, the sealing device 4 has a ring-shaped case 8 having an opening facing the inner ring 2, a ring-shaped seal body 9 provided in the case 8, a biasing member 10 (hereinafter referred to as radial biasing member 10a) that biases the seal body 9 in a direction protruding from the opening, and a biasing member 10 (hereinafter referred to as axial biasing member 10b) that biases the seal body 9 in a direction perpendicular to the protruding direction.

[0024] The case 8 has enough rigidity to withstand changes in the internal pressure of the bearing space and maintain its shape. The case 8 is composed of an inner case 8a located on the axially inner side of the bearing 1, and an outer case 8b located on the axially outer side. A flange 8c extending axially outward is formed on the outer periphery of the inner case 8a. The inner case 8a and the outer case 8b are fixed together with fastening members 11 (bolts) with the tip of this flange 8c abutting against the inner surface of the outer periphery of the outer case 8b. By fixing the inner case 8a and the outer case 8b together, an annular space having an opening facing the inner ring 2 is formed inside the case 8. The case 8 is fixed to the outer ring 3 by the fastening members 11.

[0025] The seal body 9 protrudes from an opening formed in the case 8 and contacts the outer peripheral surface of the inner ring 2. This seal body 9 is made of a material that is less rigid than the case 8 and is resistant to temperature changes, and for example, when the case 8 is made of a metal such as stainless steel or a titanium alloy, the seal body 9 can be made of polyetheretherketone (PEEK) or a fluororesin whose main component is polytetrafluoroethylene (PTFE).

[0026] As shown in Figs. 1 to 4, in this embodiment, two seal bodies 9 are arranged in a radially concentric manner in contact with each other. Hereinafter, the seal body 9 on the radially inner side is referred to as the inner seal body 9a, and the seal body 9 on the radially outer side is referred to as the outer seal body 9b. The inner seal body 9a and the outer seal body 9b each have a joint 12 formed by cutting a part of the circumferential direction in a step shape. As shown in Figs. 3 and 4, the joint 12 of the inner seal body 9a and the joint 12 of the outer seal body 9b are formed so that their circumferential positions are shifted, specifically, at opposite positions in the circumferential direction. At both ends of the joint 12, a mating surface 13 having a normal in the axial direction is formed. The mating surfaces 13 slide at both ends of the joint 12 in the circumferential direction, so that the inner seal body 9a and the outer seal body 9b can expand and contract in diameter.

[0027] A key hole is formed between the inner seal body 9a and the outer seal body 9b, which are arranged in contact with each other, and a common key member 14 is inserted axially into the key hole and is interposed between the two seal bodies 9a and 9b. The key member 14 prevents the two seal bodies 9a and 9b from rotating relative to each other around the axis. In order to prevent the inner seal body 9a and the outer seal body 9b from rotating relative to each other around the axis, a means other than the key member 14 may be used. In addition, for example, when a frictional force of a predetermined magnitude is generated between the inner seal body 9a and the outer seal body 9b to limit the relative rotation, a configuration without using the key member 14 may be used.

[0028] The radial biasing member 10a is housed inside an annular space formed in the case 6. In this embodiment, a coil spring having an inner diameter smaller than the outer diameter of the outer seal body 9b in a no-load state is used as the radial biasing member 10a. The seal body 9 is pressed toward the outer peripheral surface of the inner ring 2 by the inner peripheral edge of this radial biasing member 10a. In addition to the coil spring, a C-shaped spring having an inner diameter smaller than the outer diameter of the outer seal body 9b can also be used.

[0029] The axial biasing member 10b is provided so as to be interposed between the inner surface of the case 8 (inner case 8a) and the seal body 9 (inner diameter seal body 9a, outer diameter seal body 9b). The axial biasing member 10b is provided on the non-exposed side where foreign matter outside the bearing does not directly contact, that is, on the axially inner side of the seal body 9. In this embodiment, a wave spring is used as the axial biasing member 10b. This wave spring can be either a single-wound type or a multiple-wound type. The seal body 9 is pressed toward the outer case 8b by this axial biasing member 10b. The seal body 9 can also be configured to be biased in the axial direction by an elastic body other than a wave spring.

[0030] In order to adapt to a wide range of temperatures from extremely low to high in the space environment, it is preferable to use metals such as stainless steel and titanium alloys as the materials for the case 8 (inner case 8a, outer case 8b), fastening members 11, key members 14, radial biasing members 10a, and axial biasing members 10b, and it is preferable to use polyether ether ketone (PEEK) or a fluorine-based resin mainly composed of polytetrafluoroethylene (PTFE) as the materials for the seal body 9 and solid lubricant 5, but the types of materials are merely examples and are not limited to these.

[0031] The operation of the bearing 1 according to the above embodiment will be described. The seal body 9 (inner seal body 9a, outer seal body 9b) is biased by the biasing force of the radial biasing member 10a, and the inner seal body 9a is pressed against the outer circumferential surface of the inner ring 2. When the bearing 1 is placed in a low-pressure environment such as space and the internal pressure of the bearing space increases relatively, the seal body 9, which is a weak part of the sealing device 4 relative to the case 8, expands in diameter against the biasing force of the radial biasing member 10a (see the arrow in FIG. 3), and air in the bearing space escapes from a gap generated between the seal body 9 and the outer circumferential surface of the inner ring 2. When the internal pressure of the bearing space decreases, the seal body 9 is again pressed against the outer circumferential surface of the inner ring 2 by the biasing force of the radial biasing member 10a, ensuring the sealing of the bearing space.

[0032] In addition, the air inside the sealing device 4 is allowed to escape through the gaps in the wave spring used as the axial biasing member 10b to the inner diameter side of the seal body 9, where it merges with the air in the bearing space and is released to the outside of the bearing 1.

[0033] In the above embodiment, the inner ring 2 is made of an α+β or α type titanium alloy containing primary α crystal grains and secondary α crystal grains provided with an oxygen diffusion layer 7, and the outer ring 3 and the sealing device 4 are provided with a solid lubricant 5, but the outer ring 3 can also be made of the titanium alloy provided with an oxygen diffusion layer 7, and the inner ring 2 can be provided with a solid lubricant 5. Both the inner ring 2 and the outer ring 3 can also be made of the titanium alloy provided with an oxygen diffusion layer 7.

[0034] A modified example of the bearing 1 shown in FIG. 1 is shown in FIGS. 5 to 7. The bearing 1 according to this modified example has a basic configuration in common with the bearing 1 shown in FIG. 1, but the configuration of the sealing device 4 is partially different. In the sealing device 4 according to this modified example, two seal bodies 9 are arranged in contact with each other concentrically in the axial direction. Hereinafter, the seal body 9 on the inner side in the axial direction is referred to as the inner seal body 9c, and the seal body 9 on the outer side in the axial direction is referred to as the outer seal body 9d. The joints 12 between the inner seal body 9c and the outer seal body 9d are formed so that their circumferential positions are shifted, specifically, at opposite positions in the circumferential direction. At both ends of the joint 12, mating surfaces 13 having a normal in the radial direction are formed. The mating surfaces 13 slide at both ends of the joint 12 in the circumferential direction, so that the inner seal body 9c and the outer seal body 9d can expand and contract in diameter.

[0035] A key hole is formed between the inner seal body 9c and the outer seal body 9d, which are arranged in contact with each other, and a common key member 14 interposed between the two seal bodies 9c, 9d is inserted from the radial direction into the key hole. The function of this key member 14 is the same as described above, so a description thereof will be omitted.

[0036] Similar to the configuration shown in Fig. 1, the inner ring 2 is made of an α+β or α type titanium alloy containing primary α grains and secondary α grains, and is provided with a sliding surface 6 facing the outer ring 3. The sliding surface 6 is provided with an oxygen diffusion layer 7 in which the oxygen concentration decreases with depth from the surface.

[0037] In this modification, the inside diameter of case 8 is larger than the inside diameter of seal body 9 and smaller than the diameter of mating surface 13 of seal body 9. This prevents foreign matter from entering through joint 12, while ensuring a high level of sealing by ensuring reliable contact between the outer circumferential surface of inner ring 2 and seal body 9.

[0038] In any of the above embodiments, an α+β type or α type titanium alloy is used as the titanium alloy forming the sliding surface 6. Examples of α+β type titanium alloys include Ti-6Al-4V and Ti-6Al-2Sn-4Zr-6Mo, and examples of α type titanium alloys include Ti-5Al-2.5Sn and Ti-8Al-1Mo-1V.

[0039] The sliding surface 6 of the bearing 1 made of the titanium alloy is strengthened by increasing the surface hardness through a series of processes described below. The titanium alloy used in the bearing 1 contains a plurality of α grains. The α grains are grains made of the α phase. The α grains include primary α grains and secondary α grains. The primary α grains are grains made of the primary α phase. The secondary α grains are grains made of the secondary α phase.

[0040] The primary α phase is the α phase that remains without transforming into the β phase in any of the solution treatment process, aging treatment process, and pickling treatment process described below. The secondary α phase is the α phase that is formed by martensitic transformation or massive transformation when cooled after being transformed into the β phase. The secondary α phase includes the α' phase with a hcp structure and the α'' phase with an orthorhombic structure.

[0041] Primary α grains and secondary α grains can be distinguished by their shapes. Primary α grains have an elliptical shape, while secondary α grains have an acicular shape. Each α crystal phase is distinguished by its crystal orientation. Specifically, if the deviation between the crystal orientation of one α crystal phase and the crystal orientation of another α crystal phase adjacent to the first α crystal phase is 15° or more, the α crystal phases are considered to be separate α crystal grains.

[0042] The measurement of the crystal orientation (identification of each α grain boundary) is performed, for example, by using the EBSD (Electron Back Scatter Diffraction) method. In this measurement, when the difference in crystal orientation between two different points in the EBSD observation image is 15° or more, it is determined that a grain boundary exists between the two points, and the area of ​​each crystal grain is identified. Then, in the entire region of this observation image, the areas of the crystal grains are added in descending order from the largest grain to the smallest grain, and when the sum reaches 70% of the total crystal grain area in this observation image, the average value of the sizes of each crystal grain added up to that point is adopted as the "average grain size". From the viewpoint of wear resistance, fatigue strength, etc., it is preferable that fine crystal grains with an average grain size of 15 μm or less are formed on the sliding surface 6.

[0043] The oxygen concentration in the titanium alloy is measured by EPMA (Electron Probe Micro Analyzer). The titanium alloy preferably contains 0.8 mass percent or more of oxygen (O) on the surface, more preferably 1.4 mass percent or more of oxygen on the surface, and even more preferably 1.8 mass percent or more of oxygen on the surface.

[0044] The manufacture of the titanium alloy bearing 1, in which the sliding surface 6 contains primary α grains and secondary α grains as described above, involves the steps of preparation, solution treatment, aging treatment, pickling, and post-treatment.

[0045] The preparation process is a process in which an inner ring 2 or an outer ring 3 (hereinafter referred to as the target material), which has a sliding surface 6 made of either an α+β type titanium alloy or an α type titanium alloy, is machined to dimensions and a shape close to those of the final product.

[0046] The solution treatment process is a process in which the target material that has been machined to a certain shape in the preparation process is heated and held in a heat treatment furnace for a specified temperature and time. At this time, an inert gas such as argon, helium, or nitrogen is introduced into the furnace, and the pressure inside the furnace is set to normal pressure. The solution treatment process requires a holding process and a cooling process.

[0047] The holding step is a step of holding the target material at a predetermined holding temperature (hereinafter referred to as the "first temperature") for a predetermined time in a heat treatment furnace. The first temperature is a temperature lower than the β single-phase transformation point of the titanium alloy constituting the target material. The β single-phase transformation point is the temperature at which all of the α phase in the titanium alloy constituting the target material transforms into the β phase, and when the holding step is performed at the first temperature, a part of the α phase in the titanium alloy constituting the target material transforms into the β phase. The cooling step is a step of cooling the target material that has undergone the holding step, and is performed following the holding step. By this cooling step, the α phase that transformed into the β phase in the holding step becomes a secondary α phase.

[0048] The aging treatment process is a process for precipitating a β phase finer than the secondary α grains after the solution treatment process. In this aging treatment process, the target material is held at a predetermined temperature (hereinafter referred to as the "second temperature") for a predetermined time and then cooled. The second temperature is a temperature lower than the β transformation start point of the titanium alloy constituting the target material. The β transformation start point is the temperature at which at least a part of the α phase in the titanium alloy constituting the target material starts to transform into the β phase.

[0049] The pickling process is a process for forming a high-hardness oxygen diffusion layer 7 on the surface of the sliding surface 6 after the solution treatment process and the aging treatment process. This pickling process is carried out by holding the target material at a predetermined holding temperature (hereinafter referred to as the "third temperature") for a predetermined time. The third temperature is preferably lower than the β single-phase transformation point from the viewpoint of suppressing coarsening of crystal grains contained in the titanium alloy constituting the target material.

[0050] This acid soaking process is carried out in an atmospheric gas containing carbon dioxide (CO2). This atmospheric gas may further contain an inert gas such as argon, helium, nitrogen, etc. The pressure of the atmospheric gas is preferably normal pressure (atmospheric pressure).

[0051] The above series of treatment steps can be carried out on the entire surface of the inner ring 2 or the outer ring 3. It is also possible to provide the oxygen diffusion layer 7 only on the sliding surface 6 by masking the target material.

[0052] The conditions for the pickling treatment are explained in more detail below. That is, argon-based CO2 gas is introduced into a furnace under normal pressure, and the target titanium alloy material is heated and held in the furnace, and then cooled. When the titanium alloy is heated in a CO2 gas atmosphere, the CO2 gas dissociates into O and C on the surface of the target material, and these elements diffuse and penetrate from the surface of the target material into the interior. Note that carbon has a narrower solid solubility limit in titanium alloys than oxygen, so it has almost no effect on the solid solution strengthening of the target material.

[0053] The post-treatment process is a process in which the target material is finished to a specific dimensional accuracy by machining such as turning and polishing after the pickling process. This post-treatment process removes the brittle compound layer made of TiC, TiO2, or TiO that was formed on the surface of the target material in the pickling process. Following this post-treatment process, solid lubricant 5 molded into a specified shape is bonded to a specified position on inner ring 2 or outer ring 3, and the bearing 1 is assembled.

[0054] The sliding surfaces 6 of the inner ring 2 and the outer ring 3 manufactured by the above series of processes will have fine crystal grains with an average grain size of 15 μm or less, an oxygen concentration of approximately 0.8 percent by mass or more, and a hardness of approximately 550 Hv or more.

[0055] In the bearing 1 according to the above embodiment, the case 8 is made of a metal such as stainless steel or titanium alloy and has a rigidity that can withstand changes in the internal pressure of the bearing space and maintain its shape, so that the case 8 is unlikely to deform even if the internal pressure of the bearing space changes significantly. Therefore, the seal body 9 provided in the case 8 is securely held in place, ensuring high sealing performance. In addition, the seal body 9 is made of a resin that is resistant to temperature changes, such as a fluororesin mainly composed of polyether ether ketone or polytetrafluoroethylene, and the rigidity of the seal body 9 is relatively smaller than that of the case 8. Therefore, the seal body 9, which is a weak part of the sealing device 4, expands and contracts in diameter to allow air to escape from the bearing space, and high sealing performance is ensured even in environments where large temperature changes occur, such as in space.

[0056] Furthermore, in the bearing 1 according to each of the above embodiments, the sealing body 9 is biased by the radial biasing member 10a and the axial biasing member 10b. Therefore, even if a temperature change occurs in the bearing 1 or a diameter difference occurs between the sealing body 9 and the raceway ring due to wear or deformation of the sealing body 9, the occurrence of gaps in the sealing surface of the sealing body 9 can be prevented and the tracking ability of the sealing body 9 can be improved.

[0057] Furthermore, in the bearing 1 according to each of the above embodiments, at least one of the inner ring 2 or the outer ring 3 is provided with a sliding surface 6 made of an α+β type or α type titanium alloy, and an oxygen diffusion layer 7 is provided on this sliding surface 6, thereby achieving a weight reduction suitable for use in the space field, etc., while ensuring sufficient wear resistance and fatigue strength to withstand use in severe environments, and improving durability.

[0058] Furthermore, in the bearing 1 according to each of the above embodiments, a plurality of sealing bodies 9 have joints 12 formed by cutting a portion of the circumference thereof, and the joints 12 are arranged so that their circumferential positions are shifted. This allows the sealing bodies 9 to easily expand and contract in diameter in response to changes in the internal pressure of the bearing space, and prevents foreign matter from entering the bearing space through the joints 12.

[0059] Furthermore, in the bearing 1 according to each of the above embodiments, the multiple seal bodies 9 arranged in contact with each other are prevented from rotating relatively around the axis by the key members 14 interposed between the seal bodies 9. As a result, the relative phase of the gaps between the seal bodies 9 is fixed, making it possible to reliably prevent the intrusion of foreign matter through the gaps 12.

[0060] Furthermore, while the bearing 1 according to each of the above embodiments is configured so that the outer peripheral surface of the inner ring 2 slides against the seal body 9, it may also be configured so that the inner peripheral surface of the outer ring 3 slides against the seal body 9. In this case, the radially biasing member 10a may be, for example, a coil spring whose outer diameter in an unloaded state is larger than the inner diameter of the seal body 9, and the outer peripheral edge of this radially biasing member 10a may press the seal body 9 against the inner peripheral surface of the outer ring 3.

[0061] Furthermore, in the bearing 1 according to each of the above embodiments, the sealing device 4 is configured with two seal bodies 9, but the number can be changed as appropriate.

[0062] Furthermore, although the bearing 1 in each of the above embodiments has been described by taking a sealed sliding bearing 1 as an example, it can also be applied to a rolling bearing in which rolling elements are provided between the inner ring 2 and the outer ring 3.

[0063] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0064] 2 First component (inner ring) 3 Second component (outer ring) 4 Sealing device 5 Solid lubricant 6 Sliding surface 7 Oxygen diffusion layer 8 Cases 9 Seal body 10. Pressing member 12 Joint 13 Mating surface

Claims

1. A sliding bearing device comprising: a first member (2); a second member (3) that is arranged radially outward of the first member (2) and rotates coaxially relative to the first member (2); and a sealing device (4) that is provided between the first member (2) and the second member (3) and seals a bearing space formed between the two members (2, 3), At least one of the first member (2) and the second member (3) is provided with a sliding surface (6) made of an α+β type or α type titanium alloy containing primary α crystal grains and secondary α crystal grains, the sliding surface (6) is provided with an oxygen diffusion layer (7) in which the oxygen concentration decreases depending on the depth from the surface, the first member (2) or the second member (3) facing the sliding surface (6) is in sliding contact with the sliding surface (6) via a solid lubricant material (5) having self-lubricating properties that is provided integrally with the member (2, 3), a ring-shaped case (8) provided on one of the first member (2) or the second member (3); a ring-shaped seal body (9) provided in the case (8) and in contact with the other of the first member (2) and the second member (3); a biasing member (10) for biasing the seal body (9) against the other member; A sliding bearing device comprising:

2. The sliding bearing device according to claim 1, further comprising a biasing member (10) that biases the seal body (8) in a direction perpendicular to the direction in which the seal body protrudes.

3. 3. A sliding bearing device according to claim 2, wherein a plurality of the seal bodies (8) are arranged in concentric contact in the radial direction, a joint (12) is formed by cutting a portion of the circumferential direction of each of the seal bodies (8), and both ends of the joint (12) slide in the circumferential direction, allowing the seal body (9) to expand and contract in diameter, and the circumferential positions of the respective joints (12) of the plurality of the seal bodies (9) are arranged so as to be misaligned.

4. 4. A sliding bearing device according to claim 3, wherein both ends of abutments (12) formed in each of the seal bodies (9) slide on mating surfaces (13) having a normal in the axial direction.

5. 3. A sliding bearing device according to claim 2, wherein a plurality of the seal bodies (9) are arranged in concentric contact in the axial direction, a joint (12) is formed by cutting a portion of the circumferential direction of each of the seal bodies (9), and both ends of the joint (12) slide in the circumferential direction, allowing the seal body (9) to expand and contract in diameter, and the circumferential positions of the respective joints (12) of the plurality of the seal bodies (9) are arranged so as to be misaligned.

6. 6. A sliding bearing device according to claim 5, wherein both ends of abutments (12) formed in each of the seal bodies (9) slide on mating surfaces (13) having a normal in the radial direction.

7. 2. The sliding bearing device according to claim 1, which employs a sleeve-shaped sliding bearing structure.

8. 2. The sliding bearing device according to claim 1, which is employed in aerospace-related equipment.

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