Lubricant seal structure, wave gear device, and actuator

Abstract

The wave gear device (1) is provided with a lubricant sealing structure for preventing lubricant from leaking to the outside through the gap between the hollow input shaft (4) and the end plate (2). The lubricant sealing structure is provided with a labyrinth seal (20) for sealing the gap. The labyrinth seal (20) is composed of a plurality of gap portions (21a to 21e), and the plurality of gap portions are defined by an oil-repellent surface formed by adding fine grooves in a predetermined groove arrangement pattern. An oil-repellent surface is also formed on the outer peripheral surface portion (4d1) on the upstream side of the labyrinth seal (20). The oil-repellent effect of the oil-repellent surface on the upstream side, the sealing effect of the labyrinth seal (20), and the oil-repellent effect of the oil-repellent surface of the labyrinth seal (20) can reliably prevent the lubricant from leaking to the outside of the device.

Description

Technical Field

[0001] The present invention relates to a lubricant sealing structure for a wave gear device, an actuator having a wave gear device and a motor, or other mechanical devices. More specifically, the present invention relates to a lubricant sealing structure for preventing lubricant from leaking from the inside of the device to the outside through a first component and a second component that rotate relatively. Background Art

[0002] In a gear device such as a wave gear device, rotating side parts such as an input shaft and an output shaft are supported by fixed side parts such as a device housing via bearings. A gap is formed between the rotating side parts and the fixed side parts. In order to prevent lubricants such as lubricating oil and grease filled in the device from leaking through the gap to other parts in the device or outside the device, the gap is usually sealed with an oil seal.

[0003] Patent document 1 (Japanese Patent Publication No. 2006-258234) proposes a lubricant seal structure for improving the sealing performance of an oil seal. In this lubricant seal structure, a fluorine-based grease having oleophobicity to the lubricant is applied to the sealing portion of a rotating component constituted by the oil seal, thereby improving the sealing performance.

[0004] It is also known that a lubricant sealing structure using a labyrinth seal instead of an oil seal is used. Patent document 2 (Japanese Patent Publication No. 2007-333054) proposes the following rolling bearing device: a labyrinth gap formed between a fixed side component and a rotating side component, and an oil-repellent and water-repellent surface formed by coating an oil-repellent and water-repellent material on the surface where the labyrinth gap is formed. Patent document 3 (Japanese Patent Publication No. 2017-9085) proposes the following non-contact sealing device: a labyrinth flow path assembled between a housing and an axle of a gear device for a railway vehicle and defined by an oil-repellent treatment surface.

[0005] Here, as a surface modification technology for sliding surfaces, etc., surface texturing such as machining fine grooves on the surface of the object is known. Patent document 4 (Japanese Patent Publication No. 2017-214996) proposes the following technology: a periodic structure of fine grating-like concave and convex is formed on the sliding surface by surface processing using a femtosecond laser, thereby preventing increased friction and burning caused by insufficient lubrication. In addition, patent document 5 (Japanese Patent Publication No. 5465109) proposes the following technology: a lubricating fluid is sandwiched between two parts by laser processing, and a micro groove is formed on the sliding surface, thereby giving a higher friction reduction effect.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2006-258234

[0009] Patent Document 2: Japanese Patent Application Publication No. 2007-333054

[0010] Patent Document 3: Japanese Patent Application Publication No. 2017-9085

[0011] Patent Document 4: Japanese Patent Application Publication No. 2017-214996

[0012] Patent Document 5: Japanese Patent No. 5465109 Summary of the invention

[0013] An object of the present invention is to provide a lubricant seal structure that can reliably prevent lubricant from leaking through a gap portion between a first member and a second member that rotate relatively, by means of fine groove processing (surface texturing).

[0014] The present invention relates to a lubricant sealing structure for preventing lubricant from leaking from the inside of the device through a gap between a first component and a second component in a device having a first component and a second component that rotate relative to each other around a central axis.

[0015] It is characterized in that

[0016] The lubricant sealing structure comprises: a labyrinth seal for sealing the gap portion;

[0017] The labyrinth seal is formed between a first surface portion on the first component side and a second surface portion on the second component side that are opposed to each other.

[0018] An oleophobic surface having oleophobicity to the lubricant is formed on the first surface portion and the second surface portion, respectively.

[0019] An upstream side oil-repellent surface having the oil-repellent property is formed on at least one of a first upstream side surface portion on the upstream side in the leakage direction of the lubricant connected to the first surface portion and a second upstream side surface portion on the upstream side in the leakage direction connected to the second surface portion,

[0020] The oil-repellent surface and the upstream oil-repellent surface each have a surface texture in which fine grooves are formed in a predetermined groove arrangement pattern.

[0021] The micro groove has a groove width and a groove depth ranging from several micrometers to tens of nanometers.

[0022] The groove arrangement pattern is a pattern in which the fine grooves are arranged at intervals of several micrometers to several tens of nanometers.

[0023] In the lubricant sealing structure of the present invention, an oleophobic surface having a groove arrangement pattern with fine grooves is formed on the first surface portion and the second surface portion of the labyrinth seal that seals the gap between the first component and the second component. In addition, an upstream oleophobic surface is also formed on the first upstream surface portion and the second upstream surface portion that are located upstream of the labyrinth seal in the direction of lubricant leakage. The lubricant that leaks out through the gap is repelled by the upstream oleophobic surface and deformed into a spherical shape. By making the gap size of the labyrinth seal smaller than the size (diameter) of the spherical lubricant, the lubricant can be suppressed from flowing into the gap that defines the labyrinth seal. In addition, the labyrinth seal is defined by the oleophobic surface, so the flow of the lubricant flowing into the labyrinth seal can be suppressed.

[0024] In the lubricant sealing structure of the present invention, the oil repelling effect of the upstream oil repelling surface formed by the surface texturing based on the micro-groove processing, the sealing effect of the labyrinth seal, and the oil repelling effect of the oil repelling surface of the labyrinth seal synergistically can obtain excellent sealing performance, and can also maintain the sealing performance. Thus, it is possible to reliably prevent the lubricant from leaking from the lubricant sealing portion inside the device to the outside of the device.

[0025] Here, as the groove arrangement pattern for imparting oil repellency on the component surface, any of the following arrangement patterns (1) to (5) may be adopted, or a composite arrangement pattern obtained by combining a plurality of arrangement patterns selected from the above arrangement patterns may be adopted.

[0026] (1) The fine grooves are arranged in a pattern in which the groove intervals extend in a straight line, a curve, or a wave in a direction along the central axis of the device.

[0027] (2) The fine grooves are arranged in a pattern in which the groove intervals extend in a straight line, a curve, or a wave in a circumferential direction centered on the central axis.

[0028] (3) An arrangement pattern in which the fine grooves extend in a straight line, a curve, or a wave shape in a direction inclined relative to the direction along the central axis with the groove intervals

[0029] (4) The arrangement pattern of the fine grooves extending in a spiral shape at the groove intervals

[0030] (5) The fine grooves are arranged in a mesh pattern with the groove intervals

[0031] In the lubricant seal structure of the present invention, an oil reservoir having a large gap size can be formed in a part of the gap constituting the labyrinth seal. By capturing the lubricant intruding into the gap of the labyrinth seal in the oil reservoir, leakage of the lubricant can be reliably prevented.

[0032] In this case, an oil absorber made of a porous material such as nonwoven fabric can be mounted on the oil reservoir, thereby reliably preventing the lubricant from flowing out from the oil reservoir to the downstream side.

[0033] In addition, the inner peripheral surface of the oil reservoir can be formed as an oil-philic surface having oil-philicity for the lubricant. Thus, the lubricant stored in the oil reservoir can be effectively prevented from leaking to the downstream side.

[0034] On the other hand, a gap portion whose gap size gradually decreases toward the leakage direction of the lubricant can be formed in a part of the gap portion constituting the labyrinth seal. For example, a gap portion having a wedge-shaped cross section can be formed. By appropriately setting the gap size of the gap portion, the lubricant can be easily captured in the gap portion, thereby effectively preventing the lubricant from leaking to the downstream side. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A This is a schematic longitudinal sectional view showing a wave gear device including a lubricant seal structure according to the present invention.

[0036] Figure 1B Yes means Figure 1A An explanatory diagram of a portion 1B of a wave gear device in which a lubricant seal structure is assembled.

[0037] Figure 1C Yes means Figure 1A An explanatory diagram of a portion 1C of a wave gear device in which a lubricant seal structure is assembled.

[0038] Figure 1D Yes means Figure 1A An explanatory diagram of a portion 1D of a wave gear device in which a lubricant seal structure is assembled.

[0039] Figure 1E Yes means Figure 1B An explanatory diagram of a modified example of the lubricant seal structure shown.

[0040] Figure 2A This is a schematic longitudinal sectional view showing an actuator including the lubricant seal structure of the present invention.

[0041] Figure 2B Yes means Figure 2A FIG. 2 is an explanatory diagram of a portion 2B of an actuator assembly having a lubricant seal structure.

[0042] Figure 2C Yes means Figure 2A An explanatory diagram of a portion 2C of an actuator assembly having a lubricant seal structure.

[0043] Figure 2D Yes means Figure 2A 2D illustration of the assembly portion of the actuator having a lubricant seal structure. DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment of the lubricant seal structure to which the present invention is applied will be described with reference to the accompanying drawings. The following embodiment is a case where the lubricant seal structure of the present invention is applied to a wave gear device and an actuator having a wave gear device and a motor. The present invention can also be applied to a rotation transmission device such as a gear-type speed reducer other than a wave gear device.

[0045] [Implementation Method 1]

[0046] Figure 1A 1 is a schematic longitudinal cross-sectional view showing a wave gear device according to Embodiment 1 of the present invention. The wave gear device 1 includes: a disk-shaped end plate 2 and an end plate 3, which are opposed to each other at a predetermined interval in the direction of the central axis 1a; a hollow input shaft 4, which coaxially extends through the central portions of the end plates 2 and 3; and a wave gear mechanism 5, which is assembled between the end plates 2 and 3 in a state of coaxially surrounding the hollow input shaft 4. The hollow input shaft 4 is rotatably supported by the end plates 2 and 3 via ball bearings 6 and 7. The wave gear mechanism 5 includes: a rigid internal gear 8 formed in an annular shape; an elastic external gear 9 formed in a top hat shape; a wave generator 10 with an elliptical profile; and a cross roller bearing 11, which supports the internal gear 8 and the external gear 9 in a state of relative rotation.

[0047] The external gear 9 includes a flexible cylindrical body 9b having external teeth 9a formed thereon, a disc-shaped diaphragm 9c extending radially outward from the end of the cylindrical body 9b, and an annular rigid boss 9d integrally formed on the outer peripheral edge of the diaphragm 9c. The portion on the opening end side of the cylindrical body 9b having the external teeth 9a formed thereon is coaxially arranged inside the internal gear 8. A wave generator 10 is coaxially embedded inside the portion on the opening end side of the cylindrical body 9b. The wave generator 10 includes a plug portion 10a integrally formed on the outer peripheral surface of the hollow input shaft 4, and a wave bearing 10b mounted on the elliptical outer peripheral surface of the plug portion 10a. The cylindrical body 9b of the external gear 9 is bent into an elliptical shape by the wave generator 10, so that the portions of the external teeth 9a located at both ends of its major axis mesh with the internal teeth 8a of the internal gear 8.

[0048] The boss 9d of the external gear 9 is sandwiched between the end plate 2 and the outer ring 12 of the cross roller bearing 11 from both sides in the direction of the central axis 1a, and in this state, the three components are fastened and fixed. The internal gear 8 is sandwiched between the end plate 3 and the inner ring 13 of the cross roller bearing 11 from both sides in the direction of the central axis 1a, and in this state, the three components are fastened and fixed.

[0049] The hollow input shaft 4 is a rotation input member connected to a motor or the like. When the hollow input shaft 4 rotates, the wave generator 10 rotates integrally with the hollow input shaft 4, so that the meshing position of the external gear 9 relative to the internal gear 8 moves in the circumferential direction. A relative rotation corresponding to the difference in the number of teeth between the two gears 8 and 9 occurs. For example, the end plate 2 to which the external gear 9 is fastened serves as a fixed side member, and the end plate 3 to which the internal gear 8 is fastened serves as a rotation output member, and relative rotation (reduced rotation) is output from the end plate 3.

[0050] The lubricated parts inside the wave gear device 1 include the meshing part between the external gear 9 and the internal gear 8, the contact part between the external gear 9 and the wave generator 10, the wave bearing 10b of the wave generator 10, the sliding part of the cross roller bearing 11, the sliding part of the ball bearings 6 and 7, etc. The wave gear device 1 is assembled with a lubricant seal structure for preventing the lubricant sealed or applied to the above parts from leaking from the inside of the device to the outside. The wave gear device 1 of this example includes: a portion 1B, in which a lubricant seal structure including a labyrinth seal 20 is assembled; a portion 1C, in which a lubricant seal structure including a labyrinth seal 30 is assembled; and a portion 1D, in which a lubricant seal structure including a labyrinth seal 40 is assembled.

[0051] The lubricant sealing structure with the labyrinth seal 20 at the portion 1B seals between the end plate 2 and the shaft end 4a of one side of the hollow input shaft 4, and prevents the lubricant from leaking out of the device from the lubricant sealing portion 26 between the external gear 9 between the end plates 2 and 3 and the hollow input shaft 4, and the ball bearing 6 portion. The lubricant sealing structure with the labyrinth seal 30 at the portion 1C seals between the end plate 3 and the shaft end 4b of the other side of the hollow input shaft 4, and prevents the lubricant from leaking out of the device from the lubricant sealing portion 26 and the ball bearing 7 portion. The lubricant sealing structure with the labyrinth seal 40 at the portion 1D seals between the outer ring 12 and the inner ring 13 of the cross roller bearing 11, and prevents the lubricant from leaking out of the device from the lubricant sealing portion 46 formed between the external gear 9, the cross roller bearing 11, and the internal gear, and the cross roller bearing 11 portion.

[0052] (Lubricant seal structure of part 1B)

[0053] Figure 1B This is an explanatory diagram showing a lubricant sealing structure provided with a labyrinth seal 20 that seals between the end plate 2 and the shaft end 4a of the hollow input shaft 4. The shaft end 4a of one side of the hollow input shaft 4 is rotatably supported by the end plate 2 via a ball bearing 6. The shaft end 4a of the hollow input shaft 4 protrudes to the outside of the device through the center portion of the end plate 2. A gap is formed between the end plate 2 and the shaft end 4a of the hollow input shaft 4, which communicates with the outside of the device from the ball bearing 6 side (lubricant sealing portion 26 side). This gap is sealed by the labyrinth seal 20.

[0054] An annular member 22 is mounted in the gap between the end plate 2 and the shaft end 4a of the hollow input shaft 4. The annular member 22 is pressed and fixed to the outer peripheral surface portion 4c of the shaft end 4a of the hollow input shaft 4. An annular protrusion 2a protruding inward is formed on the inner peripheral surface of the end plate 2 so as to face the annular member 22 in the axial direction. The labyrinth seal 20 is formed between the surface portion 2b on the side of the annular protrusion 2a of the end plate 2 and the surface portion 22a on the side of the annular member 22 of the hollow input shaft 4 facing the annular member 22.

[0055] The labyrinth seal 20 of this example is an axial labyrinth seal, and gap portions 21a, 21c, 21e extending in the axial direction and gap portions 21b, 21d extending in the radial direction are alternately formed from the upstream side to the downstream side in the leakage direction of the lubricant. In addition, the gap portions 21a to 21e are gap portions in which the gap portions on the downstream side are narrower than the gap portions on the upstream side. In addition, the radial gap size of the gap portion 21a on the most upstream side of the labyrinth seal 20 is set to a value smaller than the particle size of the lubricant that is repelled and spheroidized by the oil-repellent surface described below.

[0056] An oil-repellent surface having oil-repellency against lubricant is formed on the surface portion 2b on the side of the end plate 2 where the gap portions 21a to 21e are formed. Figure 1B In the figure, the area where the oil-repellent surface is formed on the surface portion 2b is indicated by a dot pattern. In addition, the surface portion 22a of the annular member 22 opposite to the surface portion 2b on the end plate 2 side and the outer peripheral surface portion 4d of the hollow input shaft 4 also have an oil-repellent surface formed. The area where the oil-repellent surface is formed on the surface portion 22a and the outer peripheral surface portion 4d is also indicated by a dot pattern. In the shaft end portion 4a of the hollow input shaft 4, an oil-repellent surface (upstream oil-repellent surface) is formed not only on the outer peripheral surface portion 4d where the gap portion 21a is formed, but also on the outer peripheral surface portion 4d1 (upstream surface portion) from the outer peripheral surface portion 4d to the outer ring assembly portion of the ball bearing 6.

[0057] The oleophobic surface of this example has a surface texture with micro grooves formed in a predetermined groove arrangement pattern so as to obtain oleophobicity to the enclosed lubricant. The micro grooves have a groove width and a groove depth of several micrometers to several tens of nanometers, and the groove arrangement pattern is a pattern in which the micro grooves are arranged at a groove interval of several micrometers to several tens of nanometers. For example, Figure 1B As schematically shown in FIG. 1 , the fine grooves 25 forming the oil-repellent surface of the outer peripheral surface portion 4 d of the hollow input shaft 4 are grooves extending in the circumferential direction and are arranged at regular intervals in the direction of the central axis 1 a .

[0058] Here, various groove arrangement patterns can be used as groove arrangement patterns of the fine grooves 25 forming the oleophobic surface. For example, the following groove arrangement pattern can be used: the fine grooves 25 extending in a straight line, a curve or a wave in the direction along the central axis 1a are formed at a certain interval in the circumferential direction. It can also be the following groove arrangement pattern: the fine grooves 25 extending in a straight line, a curve or a wave in the circumferential direction centered on the central axis 1a are formed at a certain interval in the direction of the central axis 1a. It can also be the following groove arrangement pattern: composed of fine grooves 25 extending in a straight line, a curve or a wave in a direction inclined relative to the direction along the central axis 1a. In addition, it can also be the following groove arrangement pattern: composed of fine grooves 25 extending in a spiral shape at a certain pitch in the direction of the central axis 1a. In addition, it can also be formed as: a mesh-like groove arrangement pattern in which the fine grooves 25 extending in the direction of the central axis 1a intersect with the fine grooves 25 extending in the circumferential direction. In addition, it can also be formed as: a groove arrangement pattern composed of overlapping the above groove arrangement patterns.

[0059] As described above, the hollow input shaft 4 and the end plate 2 are sealed by the labyrinth seal 20 to prevent the lubricant from leaking to the outside of the device. In addition, the gap portions 21a to 21e constituting the labyrinth seal 20 are defined by the oil-repellent surface, so that the lubricant intruding into the labyrinth seal 20 can be effectively prevented from flowing out to the outside of the device. In addition, the outer peripheral surface portion 4d1 of the hollow input shaft 4 is also an oil-repellent surface (upstream oil-repellent surface). The lubricant flowing into the labyrinth seal 20 from the ball bearing 6 side is repelled by the oil-repellent surface and deformed into spherical particles before intruding into the gap portion 21a of the labyrinth seal 20. The radial gap size of the gap portion 21a is smaller than the particle size of the spherical lubricant formed, so the lubricant can be suppressed from flowing into the gap portion 21a. In addition, among the gaps 21 a to 21 e constituting the labyrinth seal 20 , the gaps on the downstream side are narrower than the gaps on the upstream side. Therefore, the lubricant that has entered the gaps on the upstream side can be effectively prevented from flowing into the gaps on the downstream side.

[0060] Here, in this example, the gap sizes of the gap portions 21a, 21c, and 21e extending in the axial direction are the same at each position in the radial direction. In addition, the gap sizes of the gap portions 21b and 21d extending in the radial direction are also the same. A gap portion whose gap size gradually decreases from the inside of the device toward the outside of the device (a gap portion with a wedge-shaped cross section) may also be used.

[0061] For example, Figure 1E As shown, the gap portion 21a can be formed as a gap portion whose radial gap size gradually decreases from the lubricant sealing portion 26 side toward the outside of the device. For example, it is sufficient to form the inner peripheral surface portion 2c of the surface portion 2b on the end plate 2 side, which forms the gap portion 21a, into a tapered inner peripheral surface. In this case, at least its minimum gap size is set to a value smaller than the particle size of the lubricant spheroidized on the oil-repellent surface. In addition, the gap portion whose gap size gradually decreases toward the downstream side can also be applied to the following lubricant sealing structures and the lubricant sealing structures in the second embodiment described later.

[0062] (Lubricant seal structure of part 1C)

[0063] Figure 1C 1 is an explanatory diagram showing a lubricant sealing structure provided with a labyrinth seal 30 that seals between the end plate 3 and the other shaft end 4b of the hollow input shaft 4. The shaft end 4b of the hollow input shaft 4 is rotatably supported by the end plate 3 via a ball bearing 7. The shaft end 4b of the hollow input shaft 4 penetrates the center portion of the end plate 3 and protrudes to the outside of the device. A gap is formed between the end plate 3 and the shaft end 4b of the hollow input shaft 4, which is connected to the outside of the device from the ball bearing 7 side (lubricant sealing portion 26 side). The gap is sealed by the labyrinth seal 30.

[0064] An annular member 32 is mounted in the gap between the end plate 3 and the shaft end 4b of the hollow input shaft 4. The annular member 32 is pressed and fixed to the outer peripheral surface portion 4e of the shaft end 4b of the hollow input shaft 4. An annular protrusion 3a protruding inward is formed on the inner peripheral surface of the end plate 3 so as to be opposed to the annular member 32 in the axial direction. The labyrinth seal 30 is formed between the surface portion 3b on the side of the annular protrusion 3a of the end plate 3 and the surface portion 32a on the side of the annular member 32 opposed thereto.

[0065] In the labyrinth seal 30 of this example, gap portions 31a, 31c, 31e extending in the axial direction and gap portions 31b, 31d extending in the radial direction are alternately formed from the upstream side of the lubricant leakage direction toward the downstream side (toward the direction from the lubricant sealing portion 26 to the outside of the device). In addition, for the gap portions 31a to 31e, the gap portion on the downstream side is narrower than the gap portion on the upstream side. In addition, the radial gap size of the gap portion 31a on the most upstream side of the labyrinth seal 30 is set to a value smaller than the particle size of the lubricant that is repelled and spheroidized by the oil-repellent surface described below.

[0066] The surface portion 3b on the side of the end plate 3 forming each of the gap portions 31a to 31e is an oil-repellent surface having oil-repellency against the lubricant. Figure 1C In the figure, the range where the oil-repellent surface is formed is indicated by a dot pattern. The surface portion 32a of the annular member 32 opposite to the surface portion 3b is also an oil-repellent surface. The range where the oil-repellent surface is formed on the surface portion 32a is indicated by a dot pattern. In addition, at the shaft end portion 4b of the hollow input shaft, an oil-repellent surface (upstream side surface portion) is also formed on a portion of the outer peripheral surface portion 4f where the ball bearing 7 is assembled. The oil-repellent surface has the same structure as the oil-repellent surface of the labyrinth seal 20 described above, so its description is omitted.

[0067] Here, an oil storage portion is formed in the gap portion 31a of the labyrinth seal 30. That is, a groove 32b extending in the circumferential direction and having a rectangular cross-section is formed on the inner peripheral surface of the annular protrusion 3a of the end plate 3. The groove 32b is used to form an oil storage portion having a radial gap size larger than that of other parts of the gap portion 31a. In addition, the groove 32b is filled with an oil absorber 33 made of a porous material such as a non-woven fabric. In addition, the bottom portion of the groove 32b and the inner peripheral side portions on both sides are subjected to surface treatment to become an oleophilic surface that is lipophilic to the lubricating oil. Figure 1C In the figure, the formation area of ​​the oil-wet surface is represented by a mesh pattern.

[0068] The lubricant flows out from the ball bearing 7 side inside the device to the gap between the hollow input shaft 4 and the end plate 3. The lubricant can be prevented from leaking to the outside of the device by the labyrinth seal 30. In addition, the gap portions 31a to 31e constituting the labyrinth seal 30 are narrower on the downstream side than on the upstream side, so the lubricant that has intruded into the gap portion on the upstream side can be effectively prevented from flowing into the gap portion on the downstream side. In addition, the gap portions 31a to 31e constituting the labyrinth seal 30 are defined by the oil-repellent surface, so the lubricant that has intruded into the labyrinth seal 30 can be effectively prevented from flowing out toward the outside of the device. In addition, the lubricant that flows from the ball bearing 7 side toward the labyrinth seal 30 is repelled by the oil-repellent surface formed at the outer peripheral surface portion 4f of the shaft end portion 4b of the hollow input shaft 4, and is deformed into spherical particles before intruding into the gap portion 31a of the labyrinth seal 30. Since the radial gap size of the gap portion 31 a is smaller than the particle size of the formed spherical lubricant, it is possible to suppress the lubricant from flowing into the gap portion 31 a.

[0069] In addition, an oil reservoir filled with an oil absorber 33 is formed in the gap portion 31a of the labyrinth seal 30. The lubricant that has entered the labyrinth seal 30 is captured by the oil reservoir and prevented from flowing out toward the downstream side (outside the device). The inner peripheral surface of the groove forming the oil reservoir is divided into an oil-philic surface, thereby preventing the lubricant captured by the oil reservoir from flowing out toward the downstream side. In this way, the lubricating oil can be reliably prevented from leaking out of the device by the sealing effect of the labyrinth seal 30, the effect of the oil-repellent surface, and the effect of the oil reservoir having the oil absorber and the oil-philic surface.

[0070] (Lubricant seal structure of part 1D)

[0071] Next, a lubricant sealing structure including the labyrinth seal 40 that seals the gap between the outer ring 12 and the inner ring 13 of the cross roller bearing 11 will be described. Figure 1D 1 is an explanatory diagram showing a lubricant sealing structure having a labyrinth seal 40 that seals between the outer ring 12 and the inner ring 13. A gap that communicates with the outside of the device from the track groove 14 is formed between the outer ring 12 and the inner ring 13. The gap is sealed by the labyrinth seal 40. The labyrinth seal 40 is formed between the inner peripheral side surface portion 12a of the outer ring 12 and the outer peripheral side surface portion 13a of the inner ring 13 that is opposite to the inner peripheral side surface portion 12a.

[0072] In the labyrinth seal 40, gaps 41a, 41c, 41e extending in the axial direction and gaps 41b, 41d extending in the radial direction are alternately formed from the lubricant sealing portion toward the outside of the device. In addition, among the gaps 41a to 41e, the gaps on the downstream side are narrower than the gaps on the upstream side.

[0073] The inner peripheral side surface portion 12a of the outer ring 12 forming each of the gap portions 41a to 41e is an oil-repellent surface having oil-repellency against the lubricant. Figure 1D In FIG. 1 , the range where the oil-repellent surface is formed is indicated by a dot pattern. In addition, the outer peripheral side surface portion 13a of the inner ring 13 opposite to the inner peripheral side surface portion 12a is also an oil-repellent surface. Figure 1D In FIG. 1 , the range where the oil-repellent surface is formed on the outer peripheral surface portion 13 a is indicated by a dot pattern. The oil-repellent surface has the same structure as the oil-repellent surface of the labyrinth seal 20 described above, and therefore, description thereof will be omitted.

[0074] The lubricant flows out from the track groove 14 side of the cross roller bearing 11 inside the device to the gap between the outer ring 12 and the inner ring 13. The labyrinth seal 40 can prevent the lubricant from leaking to the outside of the device. In addition, in the gap portions 41a to 41e constituting the labyrinth seal 40, the gap portion on the downstream side is narrower than the gap portion on the upstream side, so the lubricant that has invaded the gap portion on the upstream side can be effectively prevented from flowing into the gap portion on the downstream side. In addition, the gap portions 41a to 41e are defined by the oil-repellent surface, so the lubricant that has invaded the labyrinth seal 40 can be effectively prevented from flowing toward the outside of the device. In this way, the lubricating oil can be reliably prevented from leaking to the outside of the device through the gap by the sealing effect brought by the labyrinth seal 40 and the oil-repellent effect brought by the oil-repellent surface.

[0075] [Implementation Method 2]

[0076] Figure 2A 1 is a schematic longitudinal sectional view showing an actuator having a lubricant seal structure of the present invention. The actuator 100 is a hollow type actuator having a hollow portion extending through the center thereof, and comprises a motor 110 and a wave gear device 120. The motor 110 comprises: a hollow motor shaft 111; a rotor 112 mounted on the outer peripheral surface of the hollow motor shaft 111; and a stator 113 coaxially surrounding the rotor 112. The hollow motor shaft 111 is rotatably supported by a motor housing 116 at both ends thereof via ball bearings (only one ball bearing 114 is shown in the figure).

[0077] A large-diameter mounting flange 117 is provided at the front end of the motor housing 116. A wave gear device 120 is coaxially mounted on the front surface of the mounting flange 117. The wave gear device 120 includes: a rigid internal gear 121; a top-hat-shaped flexible external gear 122; a wave generator 123; a cross roller bearing 124 that supports the internal gear 121 and the external gear 122 in a state of relative free rotation; and a disc-shaped output shaft 125.

[0078] The wave generator 123 includes a hollow input shaft 126 coaxially connected to the hollow motor shaft 111, and a plug 127 having an elliptical profile is integrally formed on the outer peripheral surface of the hollow input shaft 126. A wave bearing 128 is mounted on the elliptical outer peripheral surface of the plug 127. The cylindrical body portion of the external gear 122 having the external teeth 122a formed thereon is bent into an elliptical shape by the wave generator 123, so as to partially mesh with the internal teeth 121a of the internal gear 121.

[0079] The annular boss 122c of the external gear 122 is sandwiched between the mounting flange 117 and the outer ring 124a of the cross roller bearing 124, and in this state, the three components are fastened and fixed. The internal gear 121 is sandwiched between the inner ring 124b of the cross roller bearing 124 and the output shaft 125, and in this state, the three components are fastened and fixed. The output rotation of the motor 110 is input to the wave generator 123 from the hollow motor shaft 111. When the wave generator 123 rotates, the internal gear 121 is decelerated, and the decelerated rotation is output from the output shaft 125 connected to the internal gear 121 to the load side (not shown).

[0080] The lubricated parts inside the wave gear device 120 are the meshing part between the external gear 122 and the internal gear 121, the contact part between the external gear 122 and the wave generator 123, the wave bearing 128 of the wave generator 123, the cross roller bearing 124, etc. In order to prevent the lubricant from leaking from the lubricant sealing parts 131 and 132 inside the wave gear device 120 to the outside of the device or the motor 110 side, the wave gear device 120 is assembled with: a lubricant sealing structure 2B having a labyrinth seal 140, a lubricant sealing structure 2C having a labyrinth seal 150, and a lubricant sealing structure 2D having a labyrinth seal 160.

[0081] (Lubricant seal structure of part 2B)

[0082] Figure 2B 1 is an explanatory diagram showing a portion of a lubricant sealing structure having a labyrinth seal 140 that seals between the hollow input shaft 126 and the output shaft 125. The hollow input shaft 126 that rotates at a high speed and the output shaft 125 that rotates at a reduced speed are sealed by the lubricant sealing structure having the labyrinth seal 140. The internal space of the external gear 122 in which the wave bearing 128 is arranged is a lubricant sealing portion 131 (see FIG. 1 ) in which the lubricant supplied to the wave bearing 128 and the sliding portion between the wave bearing 128 and the external gear 122 is sealed. Figure 2A). A gap is formed between the hollow input shaft 126 and the output shaft 125, which communicates with the outside of the device from the wave bearing 128 located inside the device. The gap is sealed by a labyrinth seal 140. The labyrinth seal 140 is formed between a surface portion 125a on the inner peripheral side of the output shaft 125 and a surface portion 126a on the shaft end side of the hollow input shaft 126 that is opposite to the surface portion 125a on the inner peripheral side.

[0083] The labyrinth seal 140 is an axial labyrinth seal, and has gaps 141a, 141c, 141e extending in the radial direction and gaps 141b, 141d, 141f extending in the axial direction, which are alternately formed from the lubricant sealing portion toward the outside of the device. In addition, the gaps 141a to 141e are gaps in which the gaps on the downstream side are narrower than the gaps on the upstream side. In addition, the axial gap size of the gap 141a on the most upstream side of the labyrinth seal 140 is set to a value smaller than the particle size of the lubricant that is repelled and spheroidized by the oil-repellent surface described below.

[0084] An oleophobic surface having oleophobic properties to the lubricant is formed on the surface portion 125a on the inner circumference of the output shaft 125 forming each of the gap portions 141a to 141f. In addition, an oleophobic surface (upstream oleophobic surface) is also formed on the outer circumference portion 125b (upstream surface portion) connected to the inner side of the device of the gap portion 141a (upstream side in the direction of lubricant leakage). In addition, an oleophobic surface is also formed on the surface portion 126a of the hollow input shaft 126. Figure 2B In order to show the surface portion where the oleophobic surface is formed, a dot pattern is added along the surface portion. In addition, the oleophobic surface is the surface portion where fine grooves are formed in a predetermined groove arrangement pattern, similarly to the oleophobic surface on the labyrinth seal 20 side in the first embodiment described above, so their description is omitted.

[0085] The lubricant flows out from the inside of the device to the gap between the hollow input shaft 126 and the output shaft 125. The gap is sealed by the labyrinth seal 140, so the lubricant can be prevented from leaking to the outside of the device. In addition, for the gap portions 141a to 141f constituting the labyrinth seal 140, the gap portion on the downstream side is narrower than the gap portion on the upstream side, so the lubricant that has invaded the gap portion on the upstream side can be effectively prevented from flowing into the gap portion on the downstream side. In addition, the gap portions 141a to 141f are defined by the oil-repellent surface, so the lubricant that has invaded the labyrinth seal 140 can be effectively prevented from flowing out toward the outside of the device. In addition, the lubricant that has flowed into the labyrinth seal 140 is repelled by the oil-repellent surface formed at the outer peripheral surface portion 125b of the output shaft 125 and is deformed into spherical particles before invading the gap portion 141a of the labyrinth seal 140. Since the axial gap dimension of the gap portion 141 a is smaller than the particle diameter of the formed spherical lubricant, it is possible to suppress the lubricant from flowing into the gap portion 141 a .

[0086] In this way, the oil repellent effect of the upstream oil repellent surface, the sealing effect of the labyrinth seal 140 , and the oil repellent effect of the oil repellent surface defining the labyrinth seal 140 can reliably prevent the lubricating oil from leaking to the outside of the device.

[0087] (Lubricant seal structure of part 2C)

[0088] Figure 2C 1 is an explanatory diagram showing a portion of a lubricant sealing structure having a labyrinth seal 150 that seals between the wave gear device 120 and the motor 110. The lubricant sealing structure can prevent the lubricant from leaking from the wave gear device 120 side to the motor 110 side. A ball bearing 114 is mounted between the inner peripheral edge 117a of the mounting flange 117 and the shaft end 111a of the hollow motor shaft 111 facing the mounting flange 117. The front end of the shaft end 111a of the hollow motor shaft 111 penetrates the mounting flange 117 and protrudes toward the wave gear device 120 side. The hollow input shaft 126 of the wave gear device 120 is coaxially connected and fixed to the shaft end 111a of the hollow motor shaft 111.

[0089] A gap is formed between the inner peripheral edge portion 117a of the mounting flange 117 and the hollow input shaft 126 opposed thereto. The gap is sealed by a labyrinth seal 150. The labyrinth seal 150 is formed between a surface portion 117b of the inner peripheral edge portion 117a of the mounting flange and a surface portion 126c of the shaft end of the hollow input shaft 126 opposed to the surface portion 117b in the axial direction.

[0090] The labyrinth seal 150 is configured to alternately form gap portions 151a, 151c, 151e extending in the radial direction and gap portions 151b, 151d extending in the axial direction from the wave gear device 120 side toward the motor 110 side. In addition, the gap portions 151a to 151e are gap portions in which the gap portions on the downstream side are narrower than the gap portions on the upstream side. In addition, the axial gap size of the gap portion 151a on the most upstream side of the labyrinth seal 150 is set to a value smaller than the particle size of the lubricant that is repelled and spheroidized by the oil-repellent surface described below.

[0091] The surface portion 117b of the inner peripheral portion 117a of the mounting flange forming each gap portion 151a to 151e is an oil-repellent surface having oil-repellency against lubricants. In addition, the surface portion 126c of the shaft end of the hollow input shaft 126 opposite to the surface portion 117b is also an oil-repellent surface. In addition, the outer peripheral surface portion 126d (upstream side surface portion) on the inner side of the device relative to the gap portion 151a is also an oil-repellent surface (upstream side oil-repellent surface). Figure 2C In order to show the surface portion where the oleophobic surface is formed, a dot pattern is added along the surface portion. In addition, the oleophobic surface is the surface portion where fine grooves are formed in a predetermined groove arrangement pattern, similarly to the oleophobic surface on the labyrinth seal 20 side described above, so their description is omitted.

[0092] The lubricant flows out from the inside of the device to the gap between the hollow input shaft 126 and the inner peripheral edge portion 117a of the mounting flange. The gap is sealed by the labyrinth seal 150, so the lubricant can be prevented from leaking to the outside of the device. In addition, for the gap portions 151a to 151e constituting the labyrinth seal 150, the gap portion on the downstream side is narrower than the gap portion on the upstream side, so the lubricant that has intruded into the gap portion on the upstream side can be effectively prevented from flowing into the gap portion on the downstream side. In addition, the gap portions 151a to 151e are defined by the oil-repellent surface, so the lubricant that has intruded into the labyrinth seal 150 can be effectively prevented from flowing out toward the outside of the device. In addition, the lubricant that has flowed into the labyrinth seal 150 is repelled by the oil-repellent surface formed at the outer peripheral surface portion 126d of the shaft end of the hollow input shaft 126, and is deformed into spherical particles before intruding into the gap portion 151a of the labyrinth seal 150. Furthermore, since the axial gap dimension of the gap portion 151 a is smaller than the particle size of the formed spherical lubricant, it is possible to suppress the lubricant from flowing into the gap portion 151 a .

[0093] In this way, the lubricating oil can be reliably prevented from leaking to the outside of the device by the oil-repellent effect of the upstream oil-repellent surface of the labyrinth seal 150, the sealing effect of the labyrinth seal 150, and the oil-repellent effect of the oil-repellent surface specified for the labyrinth seal 150.

[0094] (Lubricant seal structure of part 2D)

[0095] Figure 2D 1 is an explanatory diagram showing a portion of a lubricant sealing structure between the outer ring 124a and the inner ring 124b of the cross roller bearing 124. The portion 2D of the lubricant sealing structure having the labyrinth seal 160 is arranged at a portion of the cross roller bearing 124 that supports the external gear 122 and the internal gear 121 so as to be relatively rotatable. That is, it is arranged to seal the gap between the outer ring 124a and the inner ring 124b of the cross roller bearing 124. This lubricant sealing structure is similar to the one used in Embodiment 1. Figure 1D The lubricant sealing structure of the labyrinth seal 40 shown is substantially the same, and therefore, a detailed description thereof will be omitted.

Claims

1. A lubricant sealing structure for preventing lubricant from leaking out from inside the device through a gap between a first component and a second component in a device having a first component and a second component that rotate relative to each other about a central axis, characterized in that: The lubricant sealing structure comprises: a labyrinth seal for sealing the gap portion; The labyrinth seal is formed between a first surface portion on the first component side and a second surface portion on the second component side that are opposed to each other. An oleophobic surface having oleophobicity to the lubricant is formed on the first surface portion and the second surface portion, respectively. An upstream side oil-repellent surface having the oil-repellent property is formed on at least one of a first upstream side surface portion on the upstream side in the leakage direction of the lubricant connected to the first surface portion and a second upstream side surface portion on the upstream side in the leakage direction connected to the second surface portion, The oil-repellent surface and the upstream oil-repellent surface each have a surface texture in which fine grooves are formed in a predetermined groove arrangement pattern. The micro groove has a groove width and a groove depth ranging from several micrometers to tens of nanometers. The groove arrangement pattern is a pattern in which the fine grooves are arranged at a groove interval of several micrometers to several tens of nanometers. The labyrinth seal comprises a first gap portion having a first gap size, An oil reservoir having a second gap size larger than the first gap size is formed at a position midway in the leakage direction of the first gap portion. An oleophilic surface having oleophilicity with respect to the lubricant is formed at a portion of the first surface portion and a portion of the second surface portion defining the oil reservoir.

2. The lubricant sealing structure according to claim 1, characterized in that: The oil storage portion is provided with an oil absorber made of a porous material.

3. The lubricant sealing structure according to claim 1, characterized in that: At least a portion of the first gap portion is a gap portion whose gap size gradually decreases toward a leakage direction of the lubricant.

4. A wave gear device, comprising: Input shaft; A wave gear mechanism that reduces the speed of rotation of the input shaft and outputs the speed; a device housing that supports the input shaft in a rotatable state via a bearing; as well as The lubricant seal structure according to claim 1 is arranged to prevent the lubricant from leaking from the inside of the device to the outside through the gap portion formed between the device housing as the first component and the input shaft as the second component.

5. An actuator, comprising: motor; a wave gear device including an input shaft coaxially connected to the motor, a wave gear reduction mechanism for reducing the speed of rotation of the input shaft, and an output shaft for outputting the reduced rotation; and The lubricant seal structure according to claim 1 is arranged to prevent the lubricant from leaking from the inside of the wave gear device to the outside through a gap portion formed between the output shaft as the first member and the input shaft as the second member.

6. An actuator, comprising: motor; a wave gear device coaxially mounted on a mounting flange provided at a front end of the motor; a motor shaft that passes through the mounting flange and extends inside the wave gear device; an input shaft coaxially connected to the front end portion of the motor shaft inside the wave gear device; and The lubricant seal structure according to claim 1 is configured to prevent lubricant from leaking from the wave gear device into the interior of the motor through a gap portion formed between the mounting flange as the first component and the motor shaft and the input shaft as the second components.

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