Flexing meshing gear device

Abstract

The present invention provides a flexural meshing gear device that prevents the cage of a vibrating body bearing from contacting the outer or inner rolling surface. The vibrating body bearing (31) has a plurality of rolling elements (31b) and a cage (31c). The cage has an annular portion (313), column portions (314) spaced apart circumferentially along the annular portion, and grooves (315) for holding the rolling elements. The column portions have an outer protrusion (316) protruding circumferentially from the radially outer end and an inner protrusion (317) protruding circumferentially from the radially inner end. The cage is configured such that, in the long shaft portion of the vibrating body (30A), the outer protrusion abuts against the rolling element to prevent the cage from contacting the inner rolling surface (311), and in the short shaft portion of the vibrating body, the inner protrusion abuts against the rolling element to prevent the cage from contacting the outer rolling surface (312).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-173987, filed on October 25, 2021. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a flexural meshing gear device. Background Technology

[0003] The flexural meshing gear device has a vibrating body bearing between the flexible external gear and the vibrating body, thereby achieving smooth relative rotation between the external gear and the vibrating body.

[0004] Furthermore, the vibratory bearing has a plurality of rolling elements arranged in the direction of rotation and an annular cage that limits the spacing between the rolling elements (for example, see Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-60423

[0006] In the above-mentioned flexural meshing gear device, the contact between the outer or inner rolling surface of each rolling element of the vibrating body bearing and the cage is not considered. Summary of the Invention

[0007] The purpose of this invention is to suppress contact between the cage of the vibrating body bearing and the outer or inner rolling surface.

[0008] This invention provides a flexural meshing gear device, comprising a vibrating body, an external gear flexed and deformed by the vibrating body, an internal gear meshing with the external gear, and a vibrating body bearing disposed between the vibrating body and the external gear. In the flexural meshing gear device,

[0009] The vibratory bearing has multiple rolling elements and a cage for holding the multiple rolling elements.

[0010] The cage has an annular portion, a plurality of column portions extending axially from the annular portion and spaced apart circumferentially along the annular portion, and grooves formed between the column portions for retaining the rolling element.

[0011] The column portion has an outer protrusion that protrudes circumferentially from the radially outer end and an inner protrusion that protrudes circumferentially from the radially inner end.

[0012] The retaining structure is configured such that, in the long axis portion of the vibrator, the outer protrusion abuts against the rolling element to prevent the retainer from contacting the inner rolling surface, and in the short axis portion of the vibrator, the inner protrusion abuts against the rolling element to prevent the retainer from contacting the outer rolling surface.

[0013] According to the present invention, it is possible to suppress contact between the cage of the vibrating body bearing and the outer or inner rolling surface. Attached Figure Description

[0014] Figure 1 This is an axial sectional view showing an embodiment of the flexural meshing gear device of the present invention.

[0015] Figure 2 This is a three-dimensional diagram showing the cage of the vibrating body bearing.

[0016] Figure 3 This is a vertical sectional view of the cage.

[0017] Figure 4 It is an enlarged sectional view of the rolling element periphery located on the long axis of the vibrating body.

[0018] Figure 5 It is an enlarged sectional view of the rolling element periphery located on the short shaft of the vibrating body.

[0019] Figure 6 It is a chart showing the appropriate range of values ​​for parameters based on the dimensions of each part of the cage.

[0020] In the diagram: 1-Flexible meshing gear device, 30-Vibration body shaft, 30A-Vibration body, 31-Vibration body bearing, 31a-Outer ring, 31b-Rolling element, 31c-Cage, 35-External gear, 301L-Long shaft, 301S-Short shaft, 311-Inner rolling surface, 312-Outer rolling surface, 313-Annular part, 314-Column part, 315-Groove, 316-Outer protrusion, 317-Inner protrusion, Cp-Ellipse, O1-Rotating shaft, d-Outer diameter. Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0022] [Overall structure of the flexible meshing gear mechanism]

[0023] Figure 1 This is an axial sectional view showing the flexural meshing gear device 1 according to an embodiment of the present invention. Additionally, in Figure 1 In the diagram, the portion above the rotating shaft O1 of the flexural meshing gear device 1 is a cross-sectional view including the direction along the long axis of the vibrating body 30A (described later), and the portion below the rotating shaft O1 is a cross-sectional view including the direction along the short axis of the vibrating body 30A.

[0024] In the following description, the direction parallel to the rotation axis O1 described later is called the axial direction, the circumferential direction along the circle centered on the rotation axis O1 is called the circumferential direction, and the radial direction along the circle centered on the rotation axis O1 is called the radial direction.

[0025] The flexural gear mechanism 1 is, for example, a speed reduction device. The application of the flexural gear mechanism 1 is not particularly limited and can be used for a variety of purposes.

[0026] The flexural meshing gear device 1 includes a vibrating body shaft 30, a vibrating body bearing 31, an external gear 35, a first internal gear 411 (internal gear), a second internal gear 421 (internal gear), a housing 43, a first cover 44, a second cover 45, input bearings 46 and 47, a main bearing 48, and stop rings 51 and 52 as limiting components.

[0027] The vibrating body shaft 30 is a hollow cylindrical shaft that rotates around the rotation axis O1. It has a non-circular (e.g., elliptical) vibrating body 30A with a cross-section perpendicular to the rotation axis O1, and shaft portions 30B and 30C disposed on both axial sides of the vibrating body 30A. The ellipse does not necessarily have to be a geometrically precise ellipse; it includes approximate ellipses. The ellipse referred to here simply needs to be an oblong shape with a major axis 301L orthogonal to the rotation axis O1 and a minor axis 301S orthogonal to the major axis 301L.

[0028] Shaft sections 30B and 30C are circular shafts with a cross-section perpendicular to the rotation axis O1.

[0029] Alternatively, the vibrating body shaft 30 can also be a solid shaft.

[0030] The first internal tooth portion 411 is constructed by providing teeth on a portion of the inner periphery of the first internal tooth member 41, which is a rigid internal gear.

[0031] The second internal tooth portion 421 is constructed by providing teeth on a portion of the inner periphery of the rigid second internal tooth member 42.

[0032] The first external tooth portion 32 and the second external tooth portion 33 are integrally disposed on the outer periphery of a flexible metal cylindrical base 34, and are respectively disposed on one side and the other side in the axial direction. These first external tooth portions 32, second external tooth portions 33 and base 34 constitute an external gear 35.

[0033] Furthermore, the first external tooth portion 32 engages with the first internal tooth portion 411, and the second external tooth portion 33 engages with the second internal tooth portion 421.

[0034] The vibratory body bearing 31 is, for example, a roller bearing, and is disposed between the vibratory body 30A and the base 34 on which the first external tooth portion 32 and the second external tooth portion 33 are formed. The vibratory body 30A and the first external tooth portion 32 and the second external tooth portion 33 can rotate relative to each other via the vibratory body bearing 31.

[0035] The vibrating bearing 31 has an outer ring 31a embedded in the inner side of the base 34, a plurality of rolling elements (rollers) 31b and a cage 31c for holding the plurality of rolling elements 31b.

[0036] The plurality of rolling elements 31b have a first group of rolling elements 31b arranged radially inside the first external tooth portion 32 and the first internal tooth portion 411 and arranged circumferentially, and a second group of rolling elements 31b arranged radially inside the second external tooth portion 33 and the second internal tooth portion 421 and arranged circumferentially. These rolling elements 31b roll with the outer periphery of the vibrator 30A as the inner rolling surface 311 and the inner periphery of the outer ring 31a as the outer rolling surface 312.

[0037] Furthermore, details regarding cage 31c will be described later.

[0038] The vibrating element bearing 31 may also have an inner ring separate from the vibrating element 30A. Furthermore, the outer ring 31a may be omitted from the vibrating element bearing 31, and the inner circumference of the base 34 may be used as the outer rolling surface. The type of rolling element is not particularly limited; for example, it may be a ball. Furthermore, the number of rows of rolling elements is not limited to two; it may be one row or more than three rows.

[0039] The stop ring 51 is disposed between one end of the external gear 35 and the vibrator bearing 31 in the axial direction and the input bearing 46, and the stop ring 52 is disposed between the other end of the external gear 35 and the vibrator bearing 31 in the axial direction and the input bearing 47.

[0040] These stop rings 51 and 52 restrict the axial movement of the external gear 35 and the vibrating body bearing 31.

[0041] The housing 43 covers the outer periphery of the second internal gear member 42. An outer ring portion of a main bearing 48 is formed on the inner periphery of the housing 43, and the housing 43 supports the second internal gear member 42 for free rotation via the main bearing 48. The housing 43 is connected to the first internal gear member 41, for example, via a connecting member 431 such as a bolt.

[0042] The main bearing 48 is, for example, a crossed roller bearing, and has a plurality of rolling elements disposed between an inner ring portion integrated with the second internal gear member 42 and an outer ring portion integrated with the housing 43. Alternatively, the main bearing 48 may also be composed of a plurality of bearings (angular contact ball bearings, tapered roller bearings, etc.) axially separated between the second internal gear member 42 and the housing 43.

[0043] Furthermore, an oil seal 541 is provided between the housing 43 and the second internal gear component 42, and at a position closer to the output side than the main bearing 48, which inhibits the lubricant from flowing out axially to the outside (output side).

[0044] The first cover 44 is connected to the first internal tooth component 41, for example, via a connecting component 441 such as a bolt.

[0045] Furthermore, the first cover 44 covers the first external tooth 32 and the first internal tooth 411 from the opposite side of the output in the axial direction. The first internal tooth component 41 and the outer casing 43 are directly or indirectly connected to the external component.

[0046] Furthermore, in this embodiment, the side that connects to an external component (also called the object component, such as one of the components in the main assembly where the flexural gear mechanism 1 is assembled as a component, and which transmits power to the external component) and outputs the decelerated motion to the external component is called the output side. Figure 1 The left side of the axis, opposite to the output side, is called the output opposite side. Figure 1 (Right side of the image). An input bearing 46 is disposed between the first housing 44 and the shaft portion 30B of the vibrator shaft 30, and the vibrator shaft 30 is rotatably supported on the first housing 44. Alternatively, the input bearing 46 is exemplified as a ball bearing, but other radial bearings may also be used.

[0047] Furthermore, an oil seal 542 is provided between the first cover 44 and the shaft portion 30B of the vibrator shaft 30, and at a position further away from the output side than the input bearing 46, to prevent lubricant from flowing out axially to the outer side (output side).

[0048] The second cover 45 is connected to the second internal gear member 42, for example, via a connecting member 533 such as a bolt, and covers the second external gear portion 33 and the second internal gear portion 421 from the output side in the axial direction. The second cover 45 and the second internal gear member 42 are connected to an external member that performs the output deceleration motion (this external member is a member that rotates relative to an external member connected to the first internal gear member 41, etc.).

[0049] An input bearing 47 is disposed between the second housing 45 and the shaft portion 30C of the vibrator shaft 30, and the vibrator shaft 30 is rotatably supported on the second housing 45. The input bearing 47 is exemplified as a ball bearing, but other radial bearings may also be used.

[0050] Furthermore, an oil seal 543 is provided between the second cover 45 and the shaft portion 30C of the vibrator shaft 30, and at a position closer to the output side than the input bearing 47, to prevent lubricant from flowing out axially to the outer side (output side). Alternatively, the second cover 45 may be integrally formed with the second internal gear component 42.

[0051] Furthermore, a sealing O-ring 551 is installed between the first internal tooth component 41 and the outer casing 43.

[0052] Similarly, a sealing O-ring 552 is installed between the first inner tooth component 41 and the first cover 44, and a sealing O-ring 553 is installed between the second inner tooth component 42 and the second cover 45.

[0053] Therefore, the internal space of the flexural meshing gear device 1 (the space containing the meshing portion of the first external tooth 32 and the first internal tooth 411, the meshing portion of the second external tooth 33 and the second internal tooth 421, the main bearing 48, the input bearings 46 and 47, and the vibrating body bearing 31, etc.) is set as a lubricant-sealed space, and is sealed by oil seals 541 to 543 and O-rings 551 to 553.

[0054] [Deceleration action]

[0055] If the vibrator shaft 30 rotates via rotational motion input from a motor (not shown), the motion of the vibrator 30A is transmitted to the first external tooth 32 and the second external tooth 33. At this time, the first external tooth 32 and the second external tooth 33 are constrained to conform to the shape of the outer circumferential surface of the vibrator 30A, and when viewed axially, they flex into an elliptical shape having a major axis portion and a minor axis portion. Furthermore, the first external tooth 32 meshes with the first internal tooth 411 of the fixed first internal tooth member 41 at its major axis portion. Therefore, the first external tooth 32 and the second external tooth 33 do not rotate at the same speed as the vibrator 30A; instead, the vibrator 30A rotates relative to the inside of the first external tooth 32 and the second external tooth 33. Furthermore, accompanying this relative rotation, the first external tooth portion 32 and the second external tooth portion 33 flexurally deform by moving circumferentially at their major axis position (position on the extension line of the major axis of the vibrator 30A) and minor axis position (position on the extension line of the minor axis of the vibrator 30A). The deformation period is proportional to the rotation period of the vibrator shaft 30.

[0056] When the first external tooth 32 and the second external tooth 33 flex and deform, their long axis positions shift, thus changing the meshing position of the first external tooth 32 and the first internal tooth 411 in the rotational direction. Here, if the number of teeth in the first external tooth 32 is set to 100 and the number of teeth in the first internal tooth 411 is set to 102, then with each rotation of the meshing position, the meshing teeth of the first external tooth 32 and the first internal tooth 411 sequentially shift, thereby causing the first external tooth 32 to rotate (self-rotate). With the aforementioned number of teeth, the rotational motion of the vibrating body shaft 30 is reduced to a reduction ratio of 100:2 before being transmitted to the first external tooth 32.

[0057] On the other hand, the second external tooth 33, which shares a base 34 with the first external tooth 32, meshes with the second internal tooth 421. Therefore, the rotation of the vibrator shaft 30 causes the meshing position of the second external tooth 33 and the second internal tooth 421 to change in the rotational direction. Furthermore, the number of teeth in the second internal tooth 421 is the same as the number of teeth in the second external tooth 33. Therefore, the second external tooth 33 and the second internal tooth 421 do not rotate relative to each other, and the rotational motion of the second external tooth 33 is transmitted to the second internal tooth 421 with a reduction ratio of 1:1. Thus, the rotational motion of the vibrator shaft 30 is reduced to a reduction ratio of 100:2 and then transmitted to the second internal tooth component 42 and the second cover 45. Moreover, this reduced rotational motion is output to the external components.

[0058] [Detailed information about the cage of the vibratory bearing]

[0059] Figure 2 This is a perspective view of the cage 31c of the vibrating element bearing 31. Figure 3 This is a vertical sectional view of the cage 31c.

[0060] The vibrator bearing 31 undergoes a radially periodic deformation motion by rotating around the long and short shaft portions of the inner vibrator 30A. During this time, the cage 31c of the vibrator bearing 31 periodically alternates between moving towards the inner rolling surface 311 and towards the outer rolling surface 312.

[0061] In contrast, conventional vibratory bearing cages do not consider the need to avoid contact with the inner and outer rolling surfaces. Therefore, the cage may come into contact with either the inner or outer rolling surface when it approaches it. Furthermore, if the cage contacts the inner or outer rolling surface, the rolling elements will slip, causing their rolling to be obstructed, which may lead to increased damage or loss such as wear or breakage.

[0062] The inventors of this application focused on a protrusion used to prevent the rolling elements from falling off when assembling the rolling elements into the cage, and achieved the concept of providing an outer protrusion 316 and an inner protrusion 317 that, in addition to having the function of preventing the rolling elements from falling off, also have the function of preventing the cage 31c from contacting the inner rolling surface 311 and the outer rolling surface 312.

[0063] The detailed structure of cage 31c is described below.

[0064] As shown in the figure, the radial thickness of the cage 31c of the vibrating body bearing 31 is uniform throughout the entire circumference, and its overall shape is perfectly round when viewed from the axial direction. Furthermore, the cage 31c is made of a resin material that is more flexible than other components made of metal, but is not particularly limited to this material.

[0065] Furthermore, the cage 31c has a pair of annular portions 313 arranged axially, annular portions 313 extending axially from one side and connected to the other side annular portion 313 and having a plurality of column portions 314 spaced apart in the circumferential direction of the annular portions 313, and grooves 315 formed between the column portions 314 for holding the rolling element 31b.

[0066] Furthermore, each column portion 314 has an outer protrusion 316 that protrudes circumferentially from the radially outer end and an inner protrusion 317 that protrudes circumferentially from the radially inner end.

[0067] The overall shape of the cage 31c is a short cylindrical shape in the axial direction.

[0068] Both the outer protrusion 316 and the inner protrusion 317 have a wedge shape with a sharp front end extending circumferentially in their vertical cross-section. The outer protrusion 316 and the inner protrusion 317 are formed on a portion or entirely of the column portion 314 in the axial direction. When the rolling element 31b is a roller, the outer protrusion 316 and the inner protrusion 317 are formed over a wide range in the axial direction, and preferably over the entire axial length of the column portion 314.

[0069] Figure 4 This is an enlarged sectional view of the periphery of the rolling element 31b, which is centered on the long axis portion (on the extension line of the long axis 301L) of the vibrating body 30A. Figure 5 It is an enlarged sectional view of the rolling element 31b, which is centered on the short axis of the vibrating body 30A (on the extension line of the short axis 301S).

[0070] In addition, Figure 3 In this paper, the number of rolling elements 31b and grooves 315 is omitted to a minimum, but in reality, multiple grooves are provided at equal intervals along the circumference.

[0071] The outer protrusion 316 has a surface on the outer periphery of the retainer 31c (designated as the outer surface) and a surface on the inner side of the groove 315 (designated as the inner surface). The outer surface is continuous with the outer periphery of the retainer 31c and forms the same circumferential surface with it.

[0072] The inner protrusion 317 has an inner circumferential surface of the retainer 31c (designated as the outer surface) and an inner surface of the groove 315 (designated as the inner surface). The outer surface is continuous with the inner circumferential surface of the retainer 31c and forms the same circumferential surface with it.

[0073] The groove 315 is a through hole that is rectangular in shape and passes through the retainer 31c when viewed radially. Moreover, the groove 315 has four inner surfaces: the opposing surfaces of two adjacent column portions 314 along the circumferential direction and the opposing surfaces of a pair of annular portions 313.

[0074] The opposing surfaces (i.e., the two inner surfaces) of the two pillars 314 are each formed by a plane that is radially parallel to the middle of the two inner surfaces and axially parallel to the flexural meshing gear device 1.

[0075] The opposing surfaces (i.e., the two inner surfaces) of the pair of annular portions 313 are each formed by a plane perpendicular to the axial direction of the flexural meshing gear device 1.

[0076] Here, the dimensions of each part of the cage 31c will be explained.

[0077] The width of the inner circumferential (strictly speaking, tangential) side of the groove 315 is set as the groove width (1) (refer to...). Figure 5 ).

[0078] The interval between the front ends of the two opposing inner protrusions 317 (i.e., the opening width in the circumferential (strictly speaking, tangential) direction of the groove 315 on the inner circumferential side of the retainer 31c) is set as the inner opening width (2) (refer to...). Figure 5 ).

[0079] The interval between the front ends of the two outer protrusions 316 (i.e., the opening width in the circumferential (strictly speaking, tangential) direction of the groove 315 on the outer periphery of the retainer 31c) is set as the outer opening width (3) (refer to) Figure 5 ).

[0080] Set the radial thickness of cage 31c to the cage thickness (4) (reference) Figure 4 ).

[0081] The width of the inner side of the groove 315 in the thickness direction (through direction of the groove 315) of the retainer 31c (excluding the width of the outer protrusion 316 and the inner protrusion 317) is set as the groove depth (5) (refer to). Figure 4 ).

[0082] The radial distance (strictly speaking, the thickness direction of the cage 31c: the through direction of the groove 315) from the center of the rolling element 31b located on the long axis position (on the extension line of the long axis 301L) of the vibrator 30A to the inner protrusion 317 (the root portion) is defined as the inner protrusion side depth (6) (refer to...). Figure 4 ).

[0083] The radial distance (strictly speaking, the thickness direction of the cage 31c: the through direction of the groove 315) from the center of the rolling element 31b located on the long axis position (on the extension line of the long axis 301L) of the vibrator 30A to the outer protrusion 316 (the root portion) is defined as the outer protrusion side depth (7) (refer to...). Figure 4 ).

[0084] Relative to the outer diameter (diameter) d of the rolling element 31b, the dimensions of (1) to (5) are set as follows: groove width (1) > d, inner opening width (2) < d, outer opening width (3) < d, cage thickness (4) < d, and groove depth (5) < d.

[0085] By setting the dimensions as described above (1) to (5), the detachment of the rolling element 31b from the groove 315 toward the radially inner and radially outer sides is suppressed.

[0086] Furthermore, by setting the dimensions as described in (1) to (5), when the rolling element 31b moves radially outward based on the vibrating body 30A, the gap between the outer periphery of the rolling element 31b and the inner surface of the outer protrusion 316 is reduced.

[0087] Furthermore, when the rolling element 31b moves radially inward based on the vibrating element 30A, the gap between the outer periphery of the rolling element 31b and the inner surface of the inner protrusion 317 decreases.

[0088] Figure 3 The symbol Cp represents an ellipse connecting the center positions of each rolling element 31b. Each rolling element 31b is arranged along an ellipse Cp maintaining a certain radial distance relative to the inner rolling surface 311 and the outer rolling surface 312. Furthermore, at the major axis position of the vibrator 30A, the movement of the cage 31c towards the inner rolling surface 311 is restricted because the gap between the outer periphery of the rolling element 31b and the outer protrusion 316 is reduced. Similarly, at the minor axis position of the vibrator 30A, the movement of the cage 31c towards the outer rolling surface 312 is restricted because the gap between the outer periphery of the rolling element 31b and the inner protrusion 317 is reduced.

[0089] Therefore, it is possible to suppress contact between the cage 31c and the inner rolling surface 311 and the outer rolling surface 312.

[0090] According to the above structure, it is possible to suppress the contact between the cage 31c and the inner rolling surface 311 and the outer rolling surface 312 to a certain extent. However, it is preferable to suppress the contact between the cage 31c and the inner rolling surface 311 and the outer rolling surface 312 more strictly.

[0091] Furthermore, it is preferable that there is always a clearance between each rolling element 31b and each outer protrusion 316 and each inner protrusion 317, which is capable of forming a gap. If the clearance is insufficient, the friction between the rolling elements 31b and the outer protrusions 316 or inner protrusions 317 will increase when they come into contact, the rotation of the rolling elements 31b will be hindered, and slippage may occur.

[0092] Therefore, the inventors of this application have obtained the following insight: by appropriately setting the numerical range of the six parameters based on (1) to (7), it is possible to strictly suppress the contact between the cage 31c and the inner rolling surface 311 and the outer rolling surface 312, and even at any position between the long axis position and the short axis position, it is possible to maintain clearance between the rolling element 31b and the outer protrusion 316 and the inner protrusion 317.

[0093] In the flexural meshing gear device 1, such as Figure 6 As shown, the six parameters based on (1) to (7) above are composed of the ratio of the groove width (1) to the outer diameter d of the rolling element 31b ((1) / d), the ratio of the inner opening width (2) to the outer diameter d of the rolling element 31b ((2) / d), the ratio of the outer opening width (3) to the outer diameter d of the rolling element 31b ((3) / d), the ratio of the cage thickness (4) to the outer diameter d of the rolling element 31b ((4) / d), the ratio of the groove depth (5) to the outer diameter d of the rolling element 31b ((5) / d), the ratio of the inner protrusion side depth (6) to the outer protrusion side depth (7) α, and the ratio of the short axis deformation of the vibrator 30A to the long axis deformation β (α / β).

[0094] In addition, “ratio α” represents the value of (6) / (7).

[0095] Furthermore, "ratio β" is the ratio of the length of the deformation of the vibrating body 30A to the length of the deformation of the vibrating body 30A, that is, the value of the deformation of the short axis of the vibrating body 30A divided by the deformation of the long axis of the vibrating body 30A.

[0096] Furthermore, the "minor axis deformation of the vibrating body 30A" is the value obtained by subtracting the minor axis length of the vibrating body 30A from the equivalent circle diameter of the vibrating body 30A (the diameter of a circle whose circumference is equal to that of the vibrating body 30A).

[0097] (Minor axis deformation) = (Equivalent circle diameter) - (Minor axis length)

[0098] Furthermore, the "major axis deformation of the vibrator 30A" is the value obtained by subtracting the equivalent circle diameter of the vibrator 30A from the major axis length of the vibrator 30A.

[0099] (Major axis deformation) = (Major axis length) - (Equivalent circle diameter)

[0100] The parameters ((1) / d) to ((5) / d) mentioned above are ratios relative to the outer diameter d of the rolling element 31b. Therefore, regardless of the size of the outer diameter d of the rolling element 31b, the values ​​for achieving non-contact between the rolling element 31b and the inner and outer rolling surfaces 311 and 312, and for forming clearance between the rolling element 31b and each outer protrusion 316 and inner protrusion 317 can be determined.

[0101] Furthermore, the parameter of the comparison value (α / β) is also a ratio value. Therefore, regardless of the magnitude of the short axis deformation and long axis deformation of the vibrator 30A, the value of achieving non-contact between the cage 31c and the inner and outer rolling surfaces 311, 312 and forming the clearance between the rolling element 31b and each outer protrusion 316 and inner protrusion 317 can be determined.

[0102] Specifically, by setting the ratio ((2) / d) to a value range of 0.93 or higher and 0.97 or lower, setting the ratio ((3) / d) to a value range of 0.95 or higher and 0.99 or lower, and setting the ratio ((4) / d) to a value range of 0.55 or higher and 0.61 or lower, it is possible to more effectively prevent the inner circumference of the cage 31c from contacting the inner rolling surface 311 when the vibrator 30A moves the rolling element 31b toward the radially outward side, and the outer circumference of the cage 31c from contacting the outer rolling surface 312 when the vibrator 30A moves the rolling element 31b toward the radially inward side.

[0103] Furthermore, by setting the ratio ((1) / d) to a value range of 1.01 or higher and 1.04 or lower, setting the ratio ((5) / d) to a value range of 0.26 or higher and 0.32 or lower, and setting the contrast value (α / β) to a value range of 2.22 or higher and 3.18 or lower, in both cases where the vibrator 30A moves the rolling element 31b toward the radially outward side and when the vibrator 30A moves the rolling element 31b toward the radially inward side, each rolling element 31b can form clearance relative to the inner surface of the groove 315, each outer protrusion 316, and each inner protrusion 317.

[0104] In addition, in fact, a certain cage 31c may be affected by gravity and become in contact with the inner surface of any one of the outer protrusions 316, inner protrusions 317 or grooves 315. However, the term "forming clearance" here means, for example, in a weightless state, that the cage 31c can be configured such that all rolling elements 31b confined between the inner rolling surface 311 and the outer rolling surface 312 form a clearance relative to all outer protrusions 316 and inner protrusions 317 (including the inner surface of all grooves 315).

[0105] Figure 6 The numerical ranges of the parameters shown above are numerical ranges that can be calculated in a manner that enables the following: under various conditions, regardless of the outer diameter of the rolling element 31b, at the short axis position and the long axis position of the vibrator 30A, the inner rolling surface 311 and the outer rolling surface 312 to be in a non-contact state with the cage 31c, and clearance (gap) to be maintained between each rolling element 31b and each outer protrusion 316 and each inner protrusion 317.

[0106] The conditions are as follows: (i) the ratio β of the minor shaft deformation to the major shaft deformation, which corresponds to the minimum to maximum reduction ratio typically required in the field of flexural gear mechanisms, holds true; (ii) the dimensional tolerances based on the manufacturability of the flexural gear mechanism 1 are taken into account; and (iii) the external dimensions of each part, which are typically required in the field of flexural gear mechanisms, hold true.

[0107] [Technical Effects of the Embodiments of the Invention]

[0108] The aforementioned flexural meshing gear device 1 is configured such that, in the long shaft portion of the vibrator 30A, the outer protrusion 316 of the vibrator bearing 31 abuts against the rolling element 31b, thereby preventing the cage 31c from contacting the inner rolling surface 311, while in the short shaft portion of the vibrator 30A, the inner protrusion 317 abuts against the rolling element 31b, thereby preventing the cage 31c from contacting the outer rolling surface 312.

[0109] Therefore, when the cage 31c is located at the major axis position of the vibrator 30A, thus being closest to the inner rolling surface 311, the outer protrusion 316 prevents it from contacting the inner rolling surface 311. And when the cage 31c is located at the minor axis position of the vibrator 30A, thus being closest to the outer rolling surface 312, the inner protrusion 317 prevents it from contacting the outer rolling surface 312. Thus, even at any position on the entire circumference of the cage 31c, it is possible to effectively prevent it from contacting the inner rolling surface 311 and the outer rolling surface 312.

[0110] Therefore, regardless of whether the rolling element 31b is located in the long shaft portion or the short shaft portion, slippage of the rolling element 31b can be suppressed, thereby reducing damage such as wear or breakage, and further reducing the loss of the flexural meshing gear device 1.

[0111] Furthermore, the following parameters are set in such a way that the cage 31c avoids contact with the inner rolling surface 311 in the long shaft portion of the vibrator 30A through the outer protrusion 316 and avoids contact between the cage 31c and the outer rolling surface 312 in the short shaft portion of the vibrator 30A through the inner protrusion 317: the ratio of the inner opening width (2) to the outer diameter d of the rolling body 31b ((2) / d); the ratio of the outer opening width (3) to the outer diameter d of the rolling body 31b ((3) / d); and the ratio of the cage thickness (4) to the outer diameter d of the rolling body 31b ((4) / d).

[0112] That is, if these parameters are set, a flexural meshing gear device 1 can be realized that can effectively avoid contact with the inner rolling surface 311 and the outer rolling surface 312 at any position on the entire circumference of the cage 31c. Therefore, it has a high degree of design freedom, thereby making the design easier.

[0113] In particular, by setting the ratio ((2) / d) to 0.93 or more and 0.97 or less, setting the ratio ((3) / d) to 0.95 or more and 0.99 or less, and setting the ratio ((4) / d) to 0.55 or more and 0.61 or less, it is possible to provide a flexural meshing gear device 1 that can effectively avoid contact with the inner rolling surface 311 and the outer rolling surface 312 at any position on the entire circumference of the cage 31c.

[0114] Furthermore, the following values ​​are set in such a way that the outer protrusion 316 in the long axis portion of the vibrator 30A prevents the cage 31c from contacting the inner rolling surface 311, and the inner protrusion 317 in the short axis portion of the vibrator 30A prevents the cage 31c from contacting the outer rolling surface 312: the ratio of the groove width (1) to the outer diameter d of the rolling body 31b ((1) / d); the ratio of the groove depth (5) to the outer diameter d of the rolling body 31b ((5) / d); the ratio of the inner protrusion side depth (6) to the outer protrusion side depth (7) α to the ratio of the short axis deformation amount of the vibrator 30A to the long axis deformation amount β (α / β).

[0115] That is, if these parameters are set, when the vibrator 30A rotates, each rolling element 31b can form a clearance (gap) relative to the inner surface of the groove 315, each outer protrusion 316 and each inner protrusion 317, thus its design freedom is high, thereby making the design easier.

[0116] In particular, by setting the ratio ((1) / d) to a value range of 1.01 or higher and 1.04 or lower, setting the ratio ((5) / d) to a value range of 0.26 or higher and 0.32 or lower, and setting the comparison value (α / β) to a value range of 2.22 or higher and 3.18 or lower, when the vibrator 30A rotates, each rolling element 31b can appropriately form a clearance relative to the inner surface of the groove 315, each outer protrusion 316 and each inner protrusion 317, which can more effectively suppress the slippage of the rolling element 31b, thereby reducing damage and further reducing the loss of the flexural meshing gear device 1.

[0117] Furthermore, with the vibrator bearing 31 assembled onto the vibrator 30A, the cage 31c maintains the same shape as before assembly. This means that the cage 31c is not subjected to deformation loads caused by the contact pressure between each rolling element 31b and each outer protrusion 316 and inner protrusion 317 due to the assembly of the vibrator bearing 31, indicating that each rolling element 31b appropriately forms clearance relative to the inner surface of the groove 315, each outer protrusion 316, and each inner protrusion 317. Therefore, a flexural meshing gear device 1 can be provided that reduces damage to the rolling elements 31b and minimizes losses.

[0118] [other]

[0119] The details shown in the above embodiments may be appropriately modified without departing from the spirit of the invention.

[0120] For example, in the above embodiment, an example of a cylindrical structure for the flexural meshing gear device 1 was described. However, the same structure as the above-described flexural meshing bearing 31 can also be used for the vibrating body bearing of flexural meshing gear devices other than cylindrical ones (e.g., cup-shaped or top-hat-shaped flexural meshing gear devices).

[0121] Furthermore, the example shown is that the rolling element 31b of the vibrating bearing 31 is a roller, but the type of rolling element is not particularly limited. For example, the rolling element can also be a ball.

Claims

1. A flexural meshing gear device comprising a vibrating body, an external gear flexed and deformed by the vibrating body, an internal gear meshing with the external gear, and a vibrating body bearing disposed between the vibrating body and the external gear, characterized in that... The vibratory bearing has a plurality of rolling elements, a cage for holding the plurality of rolling elements, an inner rolling surface located radially inside the rolling elements for the rolling elements to roll, and an outer rolling surface located radially outside the rolling elements for the rolling elements to roll. The cage has an annular portion, a plurality of column portions extending axially from the annular portion and spaced apart circumferentially along the annular portion, and grooves formed between the column portions for retaining the rolling element. The column portion has an outer protrusion that protrudes circumferentially from the radially outer end and an inner protrusion that protrudes circumferentially from the radially inner end. The retaining structure is configured such that, in the long axis portion of the vibrating body, the outer protrusion abuts against the rolling element to prevent the retainer from contacting the inner rolling surface, and in the short axis portion of the vibrating body, the inner protrusion abuts against the rolling element to prevent the retainer from contacting the outer rolling surface. In the long axis portion of the vibrating body, the rolling element moves radially outward based on the vibrating body, and the gap between the outer periphery of the rolling element and the inner surface of the outer protrusion decreases. In the short shaft portion of the vibrating body, the rolling element moves radially inward based on the vibrating body, and the gap between the outer periphery of the rolling element and the inner protrusion decreases.

2. The flexural meshing gear device according to claim 1, characterized in that, The following values ​​are set so that the cage avoids contact with the inner rolling surface by abutting the rolling element through the outer protrusion in the long shaft portion of the vibrator, and the cage avoids contact with the outer rolling surface by abutting the rolling element through the inner protrusion in the short shaft portion of the vibrator: The ratio of the opening width of the groove on the inner circumference side of the cage to the outer diameter of the rolling element, as determined by the inner protrusion. The ratio of the circumferential opening width of the groove on the outer periphery of the cage, as determined by the outer protrusion, to the outer diameter of the rolling element; The ratio of the radial thickness of the cage to the outer diameter of the rolling element.

3. The flexural meshing gear device according to claim 2, characterized in that, The ratio of the opening width of the groove on the inner circumference side of the cage, as determined by the inner protrusion, to the outer diameter of the rolling element is set to a value within the range of 0.93 or more and 0.97 or less. The ratio of the opening width of the groove on the outer periphery of the cage, as determined by the outer protrusion, to the outer diameter of the rolling element is set to a value within the range of 0.95 or more and 0.99 or less. The ratio of the radial thickness of the cage to the outer diameter of the rolling element is set to a value within the range of 0.55 or higher and 0.61 or lower.

4. The flexural meshing gear device according to claim 2 or 3, characterized in that, To prevent the cage from contacting the inner rolling surface and to prevent the cage from contacting the outer rolling surface, the following values ​​are also set: The ratio of the inner circumferential width of the groove to the outer diameter of the rolling element; The ratio of the width of the interior of the groove in the thickness direction of the cage to the outer diameter of the rolling element; The comparison value of two ratios: the ratio of the radial distance from the center of the rolling element located at the major axis position of the vibrator to the inner protrusion to the radial distance from the center of the rolling element located at the major axis position of the vibrator to the outer protrusion, and the ratio of the minor axis deformation of the vibrator to the major axis deformation.

5. The flexural meshing gear device according to claim 4, characterized in that, The ratio of the inner circumferential width of the groove to the outer diameter of the rolling element is set to a value within the range of 1.01 or higher and 1.04 or lower. The ratio of the width of the interior of the groove in the thickness direction of the cage to the outer diameter of the rolling element is set to a value within the range of 0.26 or more and 0.32 or less. The ratio of the two ratios, namely the ratio of the radial distance from the center of the rolling element located at the major axis position of the vibrator to the radial distance from the center of the rolling element located at the major axis position of the vibrator to the radial distance from the center of the rolling element located at the major axis position of the vibrator to the outer protrusion, and the ratio of the minor axis deformation of the vibrator to the major axis deformation, is set to a value within the range of 2.22 or higher and 3.18 or lower.

6. The flexural meshing gear device according to any one of claims 1 to 5, characterized in that, With the vibrator bearing assembled onto the vibrator, the cage maintains the same shape as before assembly.

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