Speed ​​reducer comprising a bearing which has a holder

Abstract

Speed ​​reducer (100) comprising: a bearing (24, 26) having a holder (40) holding several rolling elements (25) which roll between an outer ring (28) and an inner ring (27), wherein the holder (40) includes several column sections (43) which limit circumferential movements of the several rolling elements (25), and a fall-prevention section (44) formed on the column section (43) to prevent the rolling element (25) from falling in a state in which the holder (40) is installed in the outer ring (28) and the inner ring (27) is not installed in the bearing, the fall-prevention section (44) being arranged closer to one side of the column section (43) in an extension direction on an inner diameter side, the holder (40) including a fitting section (45) which fits into a recessed section (282) of the The outer ring (28) of the bearing (24, 26) fits, and the inner ring (27) of the bearing (24,26) includes a movement limiting section (273) that limits outward movement of the rolling element (25) in an axial direction.

Description

BACKGROUND OF THE INVENTION Field of invention The present invention relates to a speed reducer comprising a bearing having a holder. Description of the state of the art A planetary gear unit comprising first and second outer bearings and first and second outer rolling elements is known from JP 2002 - 161 947 A. A tapered roller bearing and a power transmission device are also known from DE 11 2014 005 332 T5. A radial angular contact roller bearing for use in a reduction device is known from WO 2019 / 170 468 A1. A speed reducer equipped with a main bearing having a rolling element is known. JP 2015 - 137 705 A describes a gear transmission device in which a carrier is supported by a housing via a bearing. This bearing is provided with an inner ring on the carrier, an outer ring on the housing, several rollers, and a holder. The housing or the carrier has a groove on a side with a large diameter for receiving an end section of the holder. SUMMARY OF THE INVENTION The inventors in this case examined a speed reducer equipped with a bearing and came to the following conclusion. The bearing contains a rolling element and a holder that surrounds the rolling element. To ensure the reliability of the speed reducer, it is important to continuously supply lubricant to the bearing's rolling element to guarantee lubrication. However, the speed reducer from JP 2015-137705A was not adequately addressed with regard to ensuring the bearing's lubrication, and there was room for improvement. The present invention was made with such a situation in mind, and one of its objectives is to provide a technique for a speed reducer to ensure the lubrication of a bearing. This problem is solved by a speed reducer according to the independent claim. According to one aspect of the present invention, a speed reducer is provided which includes a bearing having a holder that holds several rolling elements which roll between an outer ring and an inner ring, the holder comprising several column sections which limit circumferential movements of the several rolling elements, and a fall-prevention section formed on the column section to prevent the rolling element from falling off in a state in which the holder is installed in the outer ring and the inner ring is not installed in the bearing.The section for preventing falling is arranged closer to one side of the column section in an extension direction on an inner diameter side, wherein the holder includes a fitting section that fits into a recessed section of the outer ring of the bearing, and the inner ring of the bearing includes a movement limiting section that limits outward movement of the rolling element in an axial direction. Effect of the invention According to the present invention, it is possible to provide a technique for the speed reducer to ensure the lubrication of the bearing. BRIEF DESCRIPTION OF THE FIGURES Fig. 1 is a side-face cross-sectional view showing a speed reducer according to one embodiment. Fig. 2 is a cross-sectional view along line AA of the speed reducer of Fig. 1. Fig. 3 is an enlarged cross-sectional view showing a main bearing of Fig. 1. Fig. 4 is a side and front view showing an example of a bracket of Fig. 1. Fig. 5 is an enlarged view showing a column section of the bracket of Fig. 4. Fig. 6 is a diagram showing the bracket as seen from arrow B in Fig. 5. Fig. 7 is a diagram showing the bracket as seen from arrow C in Fig. 5. Fig. 8 is a cross-sectional view along line DD in Fig. 5. DETAILED DESCRIPTION OF THE INVENTION The present invention is described below with reference to each drawing based on a preferred embodiment. In the embodiment and modification examples, the same or equivalent components and elements are designated by the same reference numerals, and any duplicate descriptions are omitted. Furthermore, for ease of understanding, the dimensions of the elements in each drawing are shown at an appropriately enlarged or reduced size. Additionally, parts of the elements that are not essential for describing the embodiment in each drawing are omitted. Furthermore, terms including ordinal numbers such as first and second are used to describe different components, but the terms are only used for the purpose of distinguishing one component from other components, and the terms do not restrict the components. [Version] A configuration of a speed reducer 100 according to the embodiment of the present disclosure is described below with reference to the drawings. Fig. 1 is a side-face cross-sectional view schematically illustrating the speed reducer 100 of the present embodiment. Fig. 2 is a cross-sectional view along line AA of Fig. 1. The use of the speed reducer 100 is not limited, but the speed reducer 100 of the example can be used, for instance, for joints of an articulated robot arm. A complete configuration of the speed reducer 100 is described. The speed reducer 100 is primarily equipped with an eccentric body shaft 12, an external gear 14, an internal gear 16, supports 18 and 20, a housing 22, main bearings 24 and 26, an eccentric body bearing 30, an internal pin 32, and eccentric body shaft bearings 33 and 34. The main bearings 24 and 26 contain an inner ring 27, an outer ring 28, a holder 40, and several rolling elements 25. The main bearings 24 and 26 are exemplary bearings. Hereinafter, a direction along a central axis La of the internal gear 16 is referred to as an “axial direction of the speed reducer” or simply as an “axial direction,” and a circumferential direction and a radial direction of a circle centered on the central axis La are defined as a “circumferential direction” and a “radial direction,” respectively. Furthermore, for the sake of simplicity, one side in the axial direction (right side in the figure) is referred to below as a drive side, and the other side (left side in the figure) is referred to as a counter-drive side. This designation in such a direction does not restrict an orientation in which the speed reducer 100 is used, and the speed reducer 100 can be used in any orientation. The supports 18 and 20 comprise a first support 18, which is arranged on the opposite side of the external gear 14, and a second support 20, which is arranged on the drive side of the external gear 14. The main bearings 24 and 26 comprise a first main bearing 24, which is arranged on the opposite side of the external gear 14, and a second main bearing 26, which is arranged on the drive side of the external gear 14. The eccentric shaft bearings 33 and 34 comprise a first eccentric shaft bearing 33, which is arranged on the opposite side of the external gear 14, and a second eccentric shaft bearing 34, which is arranged on the drive side of the external gear 14. The speed reducer 100 of the present embodiment is a center-crank type in which the eccentric body shaft 12 is arranged on a coaxial line with the center axis La of the internal gear 16. The speed reducer 100 includes a hollow section H that penetrates a central section in the axial direction. The hollow section H is provided on the eccentric body shaft 12. The housing 22 forms an outer shell of the speed reducer 100. The supports 18 and 20 are arranged inside the housing 22 and rotate relative to the housing 22. The eccentric body shaft 12 has a hollow cylindrical shape with the hollow section H in the center. For example, a motor shaft is connected to an end section of the eccentric body shaft 12 on the drive side by a connecting tool, such as a bolt. The eccentric shaft 12 contains several eccentric sections 128 and functions as an eccentric body that oscillates the external gear 14. In this example, the eccentric shaft 12 contains two eccentric sections 128 that are phase-shifted by 180°. Both end sections of the eccentric shaft 12 are supported by the carriers 18 and 20 via the eccentric shaft bearings 33 and 34. The number of eccentric sections 128 is not limited to two and can be one, three, or more. The configuration of the eccentric body shaft bearings 33 and 34 is not restricted. In this example, the first eccentric body shaft bearing 33, located on the counter-drive side, is a deep groove ball bearing in which the rolling element is a ball (spherical). The rolling element rolls between the inner ring and the outer ring. The second eccentric body shaft bearing 34, located on the drive side, is a roller bearing in which the rolling element is a roller (cylindrical body). The second eccentric body shaft bearing 34 has no inner ring and no outer ring, and the rolling element rolls between an outer circumferential surface of the eccentric body shaft 12 and an inner circumferential surface of the second support 20. In the present embodiment, the eccentric bearing 30 comprises a cylindrical roller-shaped rolling element 302 and a holder. Several (for example, 38) rolling elements 302 are arranged around the eccentric section 128 at predetermined intervals. The holder rotatably holds the several rolling elements 302 in predetermined positions. The eccentric bearing 30 contains no inner ring and no outer ring, and the rolling element 302 rolls between an outer circumferential surface of the eccentric section 128 and an inner circumferential surface of a central hole 14c of the outer gear 14. As shown in Fig. 2, the outer gear 14 is rotatably mounted by the corresponding eccentric section 128 via the eccentric body bearing 30. The outer gear 14 is formed by the central hole 14c and several internal pin holes 14h. The central hole 14c is a through hole provided in the center of the outer gear 14. The several internal pin holes 14h are through holes provided at positions offset from the center of the outer gear 14. In the example of Fig. 2, ten internal pin holes 14h are arranged circumferentially at intervals of 36°. The internal pin 32 is inserted through the internal pin hole 14h. Teeth formed on an outer circumference of the outer gear 14 rotate while engaging teeth of the inner gear 16, causing the outer gear 14 to oscillate. As shown in Fig. 2, the internal gear 16 engages with the external gear 14. The internal gear 16 of the present embodiment is configured to include an internal gear body integrated with the housing 22 and an external pin 16p (pin element) rotatably mounted through the internal gear body. The external pin 16p forms an internal tooth of the internal gear 16. The number of internal teeth of the internal gear 16 (the number of external pins 16p) is slightly greater than the number of external teeth of the external gear 14 (by only one in this example). As shown in Fig. 1, the first support 18 and the second support 20 are rotatably mounted through the housing 22 via the main bearing 24 and the main bearing 26. The first support 18 supports the eccentric body shaft 12 via the first eccentric body shaft bearing 33. The second support 20 supports the eccentric body shaft 12 via the second eccentric body shaft bearing 34. The first support 18 and the second support 20 are connected to each other via the inner pin 32. The inner pin 32 penetrates the inner pin hole 14h of the outer gear 14 in the axial direction at a position that is offset in the radial direction from an axial core of the outer gear 14. One of the housing 22 and the supports 18 and 20 functions as a driven element that outputs rotational force to a driven device, and the other functions as a fixed element that is attached to an outer element to support the speed reducer 100. In the present embodiment, the driven elements are the first support 18 and the second support 20, and the fixed element is the housing 22. In the example shown in Fig. 2, ten internal pins 32 are arranged circumferentially at intervals of 36°. Fig. 1 shows one internal pin 32. The internal pin 32 is attached to the first support 18 on the counter-drive side and to the second support 20 on the drive side. The internal pin 32 connects the first support 18 and the second support 20. In the example shown in Fig. 1, the internal pin 32 is integrally formed with the first support 18, and the drive side is attached to the second support 20 by a screw B1. A sleeve 32s is provided on an outer circumference of the internal pin 32. The internal pin 32 is inserted into the internal pin hole 14h with a gap. The internal pin 32 is in contact with a portion of the internal pin hole 14h via the sleeve 32s. The internal pin 32 restricts the rotation of the external gear 14 and allows only oscillation. The main bearings 24 and 26 are arranged between the first support 18 and the housing 22, and between the second support 20 and the housing 22. The configuration of the main bearings 24 and 26 is not restricted, but in this example, they are roller bearings where the rolling elements 25 are cylindrical rollers. The holder 40 supports several rolling elements 25. The outer rings 28 of the main bearings 24 and 26 are supported by the housing 22. The inner ring of the first main bearing 24 is integrally formed with the support 18. The inner ring of the second main bearing 26 is integrally formed with the support 20. The housing 22 is a hollow cylindrical element that surrounds the supports 18 and 20. As shown in Fig. 1, an oil seal 36 is provided between the housing 22 and the first support 18 to seal lubricant from the first main bearing 24. The feature configuration of the present embodiment is described below. The present inventors have examined a speed reducer equipped with a main bearing and have obtained the following findings. One finding of the study was that improving the lubricity of the rolling elements is effective in ensuring the service life of the main bearing of the speed reducer. The main bearing contains a holder that keeps the multiple rolling elements in predetermined positions. The holder has a section that surrounds the rolling element to retain it. This surrounding section can contribute to narrowing the lubricant flow path and reducing lubricity. Furthermore, from the perspective of improving ease of assembly, it is conceivable to include a rolling element support section in the holder of the speed reducer to support the rolling element and prevent it from falling out during main bearing assembly. However, such a rolling element support section can also narrow the lubricant flow path and reduce lubricity. Based on these facts, the present inventors have developed a holder capable of ensuring lubrication while simultaneously guaranteeing easy assembly. The holder comprises a column section that limits the circumferential movement of the multiple rolling elements, and an anti-fall section formed on the column section to prevent the rolling elements from falling off. The anti-fall section is located on an inner diameter side and is positioned closer to one side of the column section.The inclusion of the anti-fall section prevents the rolling element from falling during assembly. Furthermore, by unevenly positioning the anti-fall section on one side, the lubricant flow path is ensured, and deterioration of lubricity is suppressed. The inclusion of the holder allows for the incorporation of a speed reducer, which helps ensure the longevity of the main bearing. A specific description follows. The main bearings 24 and 26 are described with reference to Fig. 1 and Fig. 3. Here, the first main bearing 24 is described, and this description also applies to the second main bearing 26. Fig. 3 is an enlarged cross-sectional view showing the first main bearing 24 from Fig. 1. As described above, the first main bearing 24 contains the outer ring 28, the holder 40, and the multiple rolling elements 25. A lubricant G is injected into the first main bearing 24. A direction along a central axis Lb of the rolling element 25 is referred to as a "rolling element axial direction," and a circumferential direction and a radial direction of a circle centered on the central axis Lb are defined as a "rolling element circumferential direction" and a "rolling element radial direction," respectively. The holder 40 is described with reference to Figs. 1, 3, 4, and 5. Fig. 4(A) is a side view of the holder 40, and Fig. 4(B) is a front view of the holder 40. In this figure, a portion of a column section 43 is broken and shown. Fig. 5 is an enlarged view showing the column section 43 of the holder 40. The holder 40 mainly comprises a large end section 41, a small end section 42, several column sections 43, several sections 44 to prevent falling, and a fitting section 45. The holder 40 is a hollow, annular element with a substantially frustoconical outer contour as a whole. One outer diameter side of the holder 40 is surrounded by the outer ring 28, and the inner ring 27 is accommodated on the inner diameter side of the holder 40. At each end of the column section 43 of the holder 40 in one direction of extension, an end face with a larger outer diameter is designated as a large end face (end face on the counter-drive side in Fig. 3), and at each end of the column section 43 of the holder 40 in the same direction of extension, an end face with a smaller outer diameter is designated as a small end face (end face on the drive side in Fig. 3).That is, the larger outer diameter of the circle drawn through the axial center of the multiple rolling elements is called one side of the large end face, and the smaller outer diameter of the circle drawn through the axial center of the multiple rolling elements is called one side of the small end face. The holder 40 contains the large end section 41 on the side of the large end face and the small end section 42 on the side of the small end face. The large end section 41 and the small end section 42 are annular elements that are essentially coaxial with the center axis La. Reference is also made to Figs. 6, 7 to 8. Fig. 6 is a view from arrow B of Fig. 5, Fig. 7 is a view from arrow C of Fig. 5, and Fig. 8 is a cross-sectional view along line DD of Fig. 5. These figures represent a pocket Pk of holder 40. The multiple column sections 43 limit the circumferential movement of the multiple rolling elements 25. In this example, the multiple column sections 43 are arranged radially around the central axis La in the same number (for example, 61) as the multiple rolling elements 25 at predetermined intervals. The column section 43 extends in a direction inclined with respect to the central axis La on the surface passing through the central axis La. The direction of extension of the column section 43 is a direction away from the central axis La as the column section 43 approaches the large end section 41. The outer diameter side of the column section 43 is connected to the large end section 41, and the inner diameter side of the column section 43 is connected to the small end section 42. As shown in Fig.As shown in Figure 6, two circumferentially adjacent column sections 43-A and 43-B, the large end section 41 and the small end section 42 form a pocket Pk with a substantially rectangular space. The rolling element 25 is received in the pocket Pk. The holder 40 includes the anti-fall section 44, which is formed on the column section 43 to prevent the rolling element 25 from falling out of the pocket Pk. The anti-fall section 44 has, for example, a claw shape. The shape of the anti-fall section 44 is not restricted, but in this example, the anti-fall section 44 is located closer to one side of either the large end section 41 or the small end section 42 of the column section 43 on the inner diameter side.In this case, by arranging the anti-fall section 44 on the inner diameter side when the rolling element 25 is inserted into the pocket Pk from the outer diameter side, the rolling element 25 is supported by the anti-fall section 44, and it is possible to prevent the rolling element 25 from falling on the inner diameter side. The fact that the anti-fall section 44 is arranged closer to one side of the column section 43 relates to a case in which the length in the extension direction of the anti-fall section 44 located on one side, with the center of the column section 43 inserted in the extension direction, is greater than the length of the anti-fall section 44 located on the other side.Therefore, the fact that the section 44 for preventing falls is located closer to one side of the column section 43 does not include the case where the area of ​​the entire section 44 for preventing falls is non-uniform in the axial direction. Furthermore, the fact that the section 44 for preventing falls is located closer to one side of the column section 43 does not include a case where the section 44 for preventing falls is present only on one side and the length of the section 44 for preventing falls on the other side is zero. The section 44 for preventing the rolling element from falling can be arranged unevenly towards the side of the small end section 42 of the column section 43, but in this example, the section 44 for preventing the rolling element from falling is arranged unevenly towards the side of the large end section 41 of the column section 43. In this case, the rolling element 25 is supported on the side of the large end section 41, and the gap is enlarged on the side of the small end section 42 so that the flow of the lubricant G can be smoothed. The shape of the anti-fall section 44 is not restricted as long as the shape can prevent the rolling element 25 from falling. In the example of Fig. 6, the anti-fall section 44 has a curved surface shape, such as an arc shape, on a section that is in contact with the curved surface of the rolling element 25. In this case, the amount of overhang near the center of the anti-fall section 44 is increased to prevent the rolling element 25 from falling, while a gap can be formed by reducing the amount of overhang in a circumferential section, and a flow path of the lubricant G can be ensured in this section. Furthermore, in the example of Fig. 6, the maximum thickness T1 of the column section 43, excluding the anti-fall section 44 on the side with the anti-fall section 44, is greater than the maximum thickness T2 on the side without the anti-fall section 44 in the circumferential direction. In this case, the stiffness on the side supported by the rolling element 25 can be increased to suppress deformation. In this example, the maximum thickness T1 is the maximum thickness of the column section 43, excluding the anti-fall section 44, on the side of the large end section 41 with the anti-fall section 44, and the maximum thickness T2 is the maximum thickness of the column section 43 on the side of the small end section 42, excluding the anti-fall section 44. Furthermore, in the example of Fig. 5, the thickness H1 on the side of the column section 43 with the anti-fall section 44, measured in the direction perpendicular to both the extension and circumferential directions and passing through the central axis line Lb, is greater than the thickness H2 on the side of the column section 43 without the anti-fall section 44. In this case, the stiffness on the side carrying the rolling element 25 can be increased to suppress deformation. In this example, thickness H1 is the maximum thickness of the column section 43 on the side of the large end section 41 with the anti-fall section 44, and thickness H2 is the maximum thickness of the column section 43 on the side of the small end section 42 without the anti-fall section 44. The fitting section 45 is described. In the example of Fig. 3, the holder 40 contains the fitting section 45, which fits into the recessed section 282 of the outer ring 28 of the first main bearing 24. In this case, the rolling element 25 is placed on the holder 40 with the large end section 41 pointing downwards, the outer ring 28 is placed therein, and the fitting section 45 is fitted into the recessed section 282, so that it is possible to treat these components as an integral unit. For example, the recessed section 282 can be a peripheral recessed section located on an inner circumferential surface of the outer ring 28. For example, the fitting section 45 can be a projection extending radially from the large end section 41. The fitting sections 45 can be provided continuously in the circumferential direction, but in the present embodiment, the fitting sections 45 are provided intermittently at predetermined intervals in the circumferential direction. In particular, the fitting section 45 is provided between the first column section 43-A and the second column section 43-B, which are arranged side by side in the circumferential direction, beneath the multiple column sections 43 in the large end section 41. In this case, the fitting section 45 can be easily fitted into the recessed section 282. In the present embodiment, the fitting section 45 is fitted into the recessed section 282 of the outer ring 28 by elastic deformation. Since, in this case, the holder 40 is temporarily attached to the outer ring 28 due to the elastic deformation, these components can easily be handled as an integral unit. For example, in this unit, the shapes of the fitting section 45 and the recessed section 282 can be adjusted to achieve a tight fit where the outer ring 28, facing downwards, does not detach under its own weight. A stepped section 433 of the column section 43 is described. In the example of Fig. 3, the stepped section 433 is provided on the surface of the column section 43 facing the rolling element 25. In this case, the column section 43 forms a gap between itself and the rolling element 25, and the lubrication is improved. The surface of the column section 43 facing the rolling element 25 can be a surface perpendicular to the circumferential direction. In the example shown in Fig. 3, the step section 433 extends in a direction inclined with respect to the extension direction of the column section 43 and in a direction perpendicular to both the extension direction and the circumferential direction. Since the gap with the rolling element 25 expands in the extension direction and the perpendicular direction, the lubrication is improved over a wide range in this case. In the example shown in Fig. 3, the step section 433 extends parallel in the axial direction (direction along the central axis line La) of the speed reducer 100. In this case, the gap with the rolling element 25 can be extended in the direction along the central axis line La. Furthermore, it is easy to machine the mold for forming the holder 40 with resin. The inner ring 27 is described with reference to Fig. 3. The inner ring 27 of the first main bearing 24 includes a movement limiting section 273, which restricts outward movement of the rolling element 25 in the axial direction. In this case, it is possible to prevent the rolling element 25 from dislodging in the axial direction. In the example of Fig. 3, the movement limiting section 273 has a collar shape that faces an end section of the rolling element 25 on the side of the large end section 41. The outer ring 28 is described with reference to Fig. 3. The outer ring 28 of the first main bearing 24 includes a retainer movement limiting section 283, which limits inward movement of the retainer 40 in the axial direction. Since this prevents the retainer 40 from coming loose, it is easy to handle the unit in which the retainer 40 is temporarily attached to the outer ring 28. In the example of Fig. 3, the retainer movement limiting section 283 is an overhanging section with a concave disk shape that overhangs inward in the radial direction. The operating principle of the speed reducer 100 configured in this way is described. When rotation is transmitted from the motor or the like to the eccentric body shaft 12, the eccentric section 128 of the eccentric body shaft 12 rotates about a centerline of rotation passing through the eccentric body shaft 12, and the outer gear 14 oscillates via the eccentric body bearing 30. As the outer gear 14 oscillates, the engagement positions of the outer gear 14 and the inner gear 16 are sequentially shifted. Consequently, each time the eccentric body shaft 12 completes one revolution, either the outer gear 14 or the inner gear 16 rotates about its axis by the amount corresponding to the difference in the number of teeth between the outer gear 14 and the inner gear 16. In the present embodiment, the outer gear 14 rotates about its axis and the delay rotation is output by the first support 18 and the second support 20 via the inner pin 32. The features of the speed reducer 100 configured in this way are described. The speed reducer 100 is a speed reducer provided with the bearing (main bearing 24, 26) which has the holder 40 for holding the multiple rolling elements 25, wherein the holder 40 includes the column section 43, which limits the circumferential movements of the multiple rolling elements 25, and the anti-fall section 44, which is formed on the column section 43 and serves to prevent the rolling element 25 from falling, and the anti-fall section 44 is arranged closer to one side of the column section 43 in the extension direction on the side of the inner diameter. Since the anti-fall section 44 is located closer to one side, this configuration makes it easy to supply the lubricant G to the main bearings 24 and 26 from the side, bypassing the anti-fall section 44. Furthermore, the gap is formed in the anti-fall section 44, ensuring a consistent flow path for the lubricant G within this gap. Previously, examples of embodiments of the present invention were described in detail. All the above descriptions of embodiments are merely specific examples for implementing the present invention. The content of the embodiment does not limit the technical scope of the present invention, and many design modifications, such as changes, additions, and omissions of components, are possible within the scope that does not deviate from the idea of ​​the invention as specified in the aspects. In the embodiment described above, the elements that can be changed in such a design are described by terms such as "the embodiment" and "in the embodiment," but this does not mean that elements without such designation may not change the design.Furthermore, the hatching applied to the cross-section of the drawing does not restrict the material of the object to which the hatching was applied. Modification examples are described below. In the drawings and descriptions of the modification examples, the same components and elements as those in the embodiment are designated with the same reference numerals. Descriptions that overlap with the embodiment are omitted where appropriate, and configurations that differ from the embodiment are described in detail. [Modification examples] The description of the exemplary embodiment shows an example in which the speed reducer 100 is a so-called speed reducer with eccentric oscillation of the center crank type, but the present invention is not limited to this. The speed reducer can be any type that has the main bearing, and the type of speed reducer is not particularly restricted.For example, the speed reducer may be a so-called eccentric oscillation speed reducer of the distribution type, in which several crankshafts are arranged at positions offset from the center, or it may be a flexible engagement speed reducer, such as a cylinder type, a pot type, or a cylinder hat type, or it may be a simple planetary gear type speed reducer, or it may be various known speed reducers, such as a parallel shaft speed reducer, a concentric shaft speed reducer, and a perpendicular shaft speed reducer. The description of the embodiment shows an example in which the inner ring of the main bearings 24 and 26 is formed integrally with the supports 18 and 20, but the inner ring of the main bearings can be a body separate from the support. In the description of the embodiment, an example was shown in which the rolling elements 25 of the main bearings 24 and 26 are cylindrical rollers, but the rolling element of the main bearing can have a shape that differs from that of the cylindrical roller, such as a tapered roller. The description of the embodiment includes an example where the number of external gears is 14, but the number of external gears can be one, three, or more. The description of the embodiment shows an example in which the inner pin 32, which contributes to transmitting the driving force of the outer gear 14, is provided as a pin element for connecting the supports 18 and 20. A support pin that does not contribute to transmitting the driving force can be provided separately from the inner pin 32 as a pin element for connecting the supports 18 and 20. The description of the embodiment shows an example in which the inner pin 32 is formed integrally with the first support 18, but the inner pin 32 can be formed separately from the first support 18 and can be connected by a fastening such as a screw. The description of the embodiment shows an example in which the eccentric body bearing 30 does not contain an inner ring and an outer ring, but the eccentric body bearing 30 may contain an inner ring or an outer ring. In the description of the embodiment, the main bearings 24 and 26 are illustrated by way of example as the bearings according to the aspects, but the bearings according to the aspects can be other bearings of the speed reducer, such as an eccentric body bearing. Each of the modification examples described above exhibits the same process and effect as the first embodiment. Any combination of the components of the embodiment described above and the modification examples can also be used as an embodiment of the present invention. New embodiments resulting from the combination exhibit the effects of each of the combined embodiment and the modification examples. Brief description of the reference symbols 100 Speed ​​reducer 25 Rolling element 27 Inner ring 28 Outer ring 40 Holder 41 Large end section 43 Column section 44 Anti-fall section 45 Fitting section 273 Movement limiting section 282 Recessed section 283 Holder movement limiting section 433 Step section

Claims

Speed ​​reducer (100) comprising: a bearing (24, 26) having a holder (40) holding several rolling elements (25) which roll between an outer ring (28) and an inner ring (27), wherein the holder (40) includes several column sections (43) which limit circumferential movements of the several rolling elements (25), and a fall-prevention section (44) formed on the column section (43) to prevent the rolling element (25) from falling in a state in which the holder (40) is installed in the outer ring (28) and the inner ring (27) is not installed in the bearing, the fall-prevention section (44) being arranged closer to one side of the column section (43) in an extension direction on an inner diameter side, the holder (40) including a fitting section (45) which fits into a recessed section (282) of the The outer ring (28) of the bearing (24, 26) fits, and the inner ring (27) of the bearing (24,26) includes a movement limiting section (273) that limits outward movement of the rolling element (25) in an axial direction. Speed ​​reducer (100) according to claim 1, wherein the section (44) is arranged closer to a side of a large end section (41) to prevent it from falling, the end section having a large outer diameter of a circle drawn through an axial center of the multiple rolling elements (25). Speed ​​reducer (100) according to claim 1 or 2, wherein the section (44) has a curved surface shape on a section which is in contact with a curved surface of the rolling element (25) to prevent it from falling off. Speed ​​reducer (100) according to one of claims 1 to 3, wherein, for a thickness in a circumferential direction, a maximum thickness (T1) of an outer ring-side end surface of the column section (43) on a side with the section (44) to prevent falling is greater than a maximum thickness (T2) of the outer ring-side end surface of the column section (43) on a side without the section (44) to prevent falling. Speed ​​reducer (100) according to one of claims 1 to 4, wherein, in the case of a thickness in a direction which passes through a central axis line of the speed reducer (100) and is perpendicular to both the extension direction and a circumferential direction of the column section (43), a thickness of the column section (43) on a side with the section (44) for preventing it from falling is greater than a thickness of the column section (43) on a side without the section (44) for preventing it from falling. Speed ​​reducer (100) according to claim 1, wherein the fitting section (45) is provided on a large end section (41) of the holder (40) between two column sections (43) arranged side by side in a circumferential direction, below the multiple column sections (43) and is fitted into the recessed section (282) of the outer ring (28) by elastic deformation. Speed ​​reducer (100) according to one of claims 1 to 6, wherein a step section (433) is provided on a surface of the column section (43) facing the rolling element (25). Speed ​​reducer (100) according to claim 7, wherein the step section (433) extends in a direction inclined with respect to the extension direction of the column section (43) and in a direction perpendicular to both the extension direction and a circumferential direction. Speed ​​reducer (100) according to one of claims 1 to 8, wherein the outer ring (28) of the bearing (24, 26) includes a holder movement limiting section (283) which limits movement of the holder (40) inwards in the axial direction. Speed ​​reducer (100) according to one of claims 1 to 9, further comprising: an internal gear (16) provided in a housing (22); an external gear (14) engaging with the internal gear (16); and a support (18, 20) arranged axially on a side section of the external gear (14), wherein the bearing (24, 26) is arranged between the housing (22) and the support (18, 20).

Images