Gear system

Abstract

To maintain sufficient moment stiffness while restricting the movement of cylindrical rollers along their axis. [Solution] The gear device is provided in which the outer race 61 of the second main bearing 6 is provided with a flange portion 61b that restricts the movement of a plurality of rollers (rolling elements) 63 in the direction along the roller axis R2, the flange portion is positioned radially outward from the rolling elements and is formed to protrude toward the roller axis from the outer ring raceway surface (rolling surface) 61a, and the flange portion further has a flange surface 61b1 that contacts the end face 63a of the roller, and the case 2 is provided with a support cylinder 2g that covers the outer race from the radially outward, the support cylinder covering at least the intersection 61p where the outer ring raceway surface and the flange surface intersect from the radially outward.

Description

Technical Field

[0001] The present invention relates to a gear device.

Background Art

[0002] In a gear device such as a transmission in which a carrier is rotatably provided in a case via bearings, for example, tapered roller bearings may be adopted as the bearings. Tapered roller bearings are suitably used in places where heavy loads, impact loads, etc. act. A tapered roller bearing includes an inner race, an outer race, and a plurality of cylindrical rollers disposed between the inner race and the outer race. The cylindrical rollers are formed in a columnar shape and are arranged such that their axes (roller axes) are inclined with respect to the axes (main axes) of the case and the carrier.

[0003] As this type of tapered roller bearing, for example, a bearing is known in which the bearing raceway surface of the outer race is curved to have an S-shaped (S-shaped course) in a sectional view, and an undercut guide is provided on the holder (see, for example, Patent Document 1). In the case of this tapered roller bearing, the movement of the cylindrical rollers in the direction along the roller axis is restricted.

[0004] Furthermore, as another conventional tapered roller bearing, for example, a tapered roller bearing provided with a flange portion on the inner race is known. In the case of this tapered roller bearing, the movement of the cylindrical rollers in the direction along the roller axis is restricted by using the flange portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In transmissions equipped with tapered roller bearings, a spacer for adjusting the preload may be placed between the inner race of the tapered roller bearing and the carrier. In this case, the preload can be adjusted by replacing the spacer during the disassembly and reassembly of the transmission. Specifically, the spacer is replaced while disassembling the transmission by loosening the carrier's fasteners, and then the carrier is re-tightened during the reassembly process.

[0007] In this case, when using a conventional tapered roller bearing with a flange formed on the inner race, a configuration is known in which the flange protrudes radially outward from the outer circumference of the carrier relative to the main axis in order to easily replace the spacer. This is because, when replacing the spacer, the transmission case and the tapered roller bearing can be temporarily assembled by, for example, pressing down on the flange with a jig. This makes it easier to remove the carrier from the tapered roller bearing and replace the spacer.

[0008] However, in this case, the flange formed on the inner race protrudes radially outward from the outer circumference of the carrier, leaving it exposed to the outside. Consequently, the flange is not surrounded by the carrier and is not supported (backed up). Therefore, when a moment load acts on the tapered roller bearing, it can cause unintended deformation, such as bending of the base portion (thin-walled portion) of the flange, potentially leading to a decrease in the moment rigidity of the transmission.

[0009] This invention has been made in consideration of these circumstances, and its purpose is to provide a gear device that can maintain sufficient moment rigidity while restricting the movement of rollers along the axis. [Means for solving the problem]

[0010] (1) A gear device according to one aspect of the present invention comprises a case rotatably arranged about a central axis, a carrier arranged radially inside the case so as to be rotatable relative to the central axis, a gear mechanism for transmitting rotation from an external source at a reduced speed to the case or the carrier, and a main bearing disposed between the case and the carrier, wherein the main bearing comprises an inner race provided on the carrier, an outer race provided on the case, and a plurality of rolling elements held rotatably between the inner race and the outer race and rotating about an axis inclined with respect to the central axis. The outer race is provided with a flange portion that restricts the movement of a plurality of rolling elements in a direction along the axis, the flange portion is positioned radially outward from the plurality of rolling elements and is formed to protrude toward the axis from the rolling surface of the outer race, and the flange portion further has a flange surface that contacts the end faces of the plurality of rolling elements, and the case is provided with a support cylinder that extends along the central axis and covers the outer race from the radially outward, the support cylinder covering at least the intersection point where the rolling surface and the flange surface intersect from the radially outward.

[0011] According to the gear apparatus of the present invention, the flange surface of the flange formed on the outer race is in contact with the end faces of the multiple rolling elements, thereby restricting unintended movement of the rolling elements in the direction along the axis. As a result, the multiple rolling elements can be stably rolled around the axis between the inner race and the outer race, and the operational reliability of the main bearing can be maintained. This allows the case and carrier to rotate relative to each other stably around the central axis.

[0012] In particular, the case has a support cylinder that surrounds the outer race from the radial outside all around. Moreover, the support cylinder covers at least from the radial outside the virtual intersection point where the rolling surface of the outer race and the flange surface of the flange intersect. Therefore, the support cylinder can cover the base portion (thin-walled portion) of the flange located near the intersection from the radial outside. This makes it possible to use the support cylinder to suppress unintended displacement (give) such as bending of the flange radially outward. Thus, the support cylinder can function as a backup member that reinforces the rigidity of the flange.

[0013] Therefore, even if, for example, a moment load acts on the main bearing during the operation of the gear mechanism, causing the flange to displace radially outward from its base, the displacement of the flange can be suppressed by using the support cylinder. As a result, a gear mechanism with sufficient moment stiffness can be achieved. Moment stiffness is the moment load value required to tilt the carrier by a unit angle relative to the case, and a larger value indicates higher stiffness.

[0014] Furthermore, unlike conventional main bearings where the flange is formed on the inner race, this bearing has the flange formed on the outer race. Therefore, even if a spacer is provided between the inner race and the carrier, the spacer can be replaced while suppressing the application of external forces to the flange. For example, when replacing a spacer, even if the inner race is held in place with a jig and the case and main bearing are temporarily assembled, external forces are less likely to act on the flange formed on the outer race. Therefore, the spacer can be replaced without requiring excessive attention to the flange. Consequently, the preload adjustment of the main bearing using spacers can be performed efficiently.

[0015] (2) The support cylinder extends along the central axis to at least reach the outer end surface of the outer race, and may cover the entire outer race from the radial outside.

[0016] In this case, the support cylinder covers the entire outer race, including the flange, from the radial outside, effectively suppressing unintended deflection and other displacements of the flange, as well as radial outward displacement of the entire outer race. Therefore, the moment rigidity of the gear mechanism can be further improved.

[0017] (3) When viewed from a direction along the axis of the rolling element, the flange is formed to protrude toward the axis from the rolling surface so as to cover 20% or more of the diameter of the rolling element, and may contact the end face of the rolling element via the flange surface.

[0018] In this case, the flange portion can be formed to be longer from the rolling surface of the outer race toward the axis of the rolling element. In particular, since the flange portion is formed to be long enough to cover more than 20% of the diameter of the rolling element when viewed from the direction along the axis, the flange surface can be used to contact the end face of the rolling element at a position close to the rotation center (axis) of the rolling element. Therefore, the rotational resistance when the rolling element starts to roll can be reduced, and the starting torque (startup torque) can be reduced. Consequently, the initial drive of the main bearing can be made more stable, and the operational reliability of the main bearing can be further improved.

[0019] (4) The flange surface may not be in contact with the portion of the end face of the rolling element that is located on the outer peripheral edge side of the rolling element.

[0020] In this case, instead of bringing the entire flange surface into contact with the end face of the rolling element, the flange surface can be brought into contact with the end face at a position close to the rotation center (axis) of the rolling element, while remaining in contact with the portion of the end face located on the outer edge of the rolling element. Therefore, the starting torque of the rolling element can be reduced more effectively. Consequently, the initial drive of the main bearing can be stabilized more effectively.

[0021] (5) The support cylinder may be in contact with the outer surface of the outer race.

[0022] In this case, since the support cylinder covers the outer race from the outside in the radial direction while being in contact with the outer peripheral surface of the outer race, displacement such as unintended deflection of the flange portion can be suppressed more effectively.

[0023] (6) The support cylinder may be formed such that a first length along the radial direction is longer than a second length along the radial direction between the outer peripheral surface of the outer race and the intersection point.

[0024] In this case, the wall thickness of the support cylinder (the first length along the radial direction) can be made longer than the thickness (the second length along the radial direction) around the root portion which is the thin portion of the flange portion in the outer race. Therefore, using a support cylinder with sufficient rigidity, displacement such as unintended deflection of the flange portion can be appropriately received.

[0025] (7) The inner race may be formed with an outer diameter larger than the outer diameter of the carrier, and a part of the inner race may be exposed outside the outer peripheral surface of the carrier in the radial direction when viewed from the direction along the central axis.

[0026] In this case, since a part of the inner race can be exposed outside the outer peripheral surface of the carrier in the radial direction, for example, when a spacer is provided between the inner race and the carrier, the replacement work of the spacer can be performed more efficiently. For example, a part of the inner race exposed outside the outer peripheral surface of the carrier in the radial direction can be pressed using a jig or the like. Thereby, the carrier can be easily removed, and the replacement work of the spacer can be performed more efficiently.

Advantages of the Invention

[0027] According to the gear device of the present invention, while restricting the movement of the rolling elements along the axis, sufficient moment rigidity can be maintained.

Brief Description of the Drawings

[0028] [Figure 1] This is a side view (partially a cross-sectional view) showing an embodiment of the gear apparatus according to the present invention. [Figure 2] This is an enlarged cross-sectional view of the area around the main bearing shown in Figure 1. [Figure 3] Figure 2 is a perspective view showing the area around the rolling element (roller). [Figure 4] This diagram illustrates the method for measuring moment stiffness using the axial loading method. [Figure 5] This diagram illustrates the method for measuring moment stiffness using the radial loading method. [Figure 6] This diagram illustrates moment stiffness in a gear system. [Modes for carrying out the invention]

[0029] Hereinafter, embodiments of the gear apparatus according to the present invention will be described with reference to the drawings. Figure 1 is a side view (partial cross-sectional view) of the gear mechanism in this embodiment. Figure 2 is an enlarged cross-sectional view of the area around the main bearing (second main bearing) shown in Figure 1.

[0030] As shown in Figure 1, the gear device 1 according to this embodiment is, for example, an eccentric oscillating type gear transmission device. The gear device 1 comprises a case 2, a carrier 3, a reduction mechanism (an example of a gear mechanism according to the present invention) 4, a first main bearing (an example of a main bearing according to the present invention) 5, a second main bearing (an example of a main bearing according to the present invention) 6, and a seal portion 7.

[0031] The carrier 3 is rotatably mounted to the case 2. The reduction mechanism 4 reduces and transmits the rotation of a drive source, such as a motor (not shown), to the case 2 or the carrier 3. The first main bearing 5 and the second main bearing 6 each rotatably support the carrier 3 relative to the case 2. The seal portion 7 seals the space between the case 2 and the carrier 3.

[0032] Case 2 is fixed to a housing (not shown). The housing, for example, houses a drive source. Case 2 is formed in a cylindrical shape with a central axis O. The inner circumferential surface 11 of case 2 is formed in a multi-stage manner along the central axis O so that it can perform different functions. Specifically, the inner circumferential surface 11 of case 2 is formed in a multi-stage manner so that it can function as an internal gear 12, a first outer race holder 13, a second outer race holder 14, and a first seal 15.

[0033] Multiple pin grooves 12a are formed in the internal gear 12. The first outer race holder 13 holds the outer race 51 of the first main bearing 5. The second outer race holder 14 holds the outer race 61 of the second main bearing 6.

[0034] In this embodiment, the direction along the central axis O is defined as the axial direction. The rotational direction of the carrier 3 around the central axis O is defined as the circumferential direction. Furthermore, the radial direction of the carrier 3 and case 2 is simply defined as the radial direction. Therefore, the radial direction intersects the central axis O when viewed from the axial direction.

[0035] In Case 2, the portion that opens towards the first block 20 constituting carrier 3 is defined as the first open end 11a. Furthermore, in Case 2, the portion that opens towards the second block 21 constituting carrier 3 is defined as the second open end 11b.

[0036] The first outer race holder 13 and the second outer race holder 14 are positioned on both sides of the internal gear 12 in the axial direction. Specifically, the first outer race holder 13 is positioned on the first open end 11a side of the internal gear 12. The second outer race holder 14 is positioned on the second open end 11b side of the internal gear 12. Therefore, the internal gear 12 is positioned in the axial direction between the first outer race holder 13 and the second outer race holder 14.

[0037] Each of the multiple pin grooves 12a extends in the axial direction. The multiple pin grooves 12a are formed at equal intervals in the circumferential direction. Each of the pin grooves 12a holds an internal tooth pin 16.

[0038] The first outer race retainer 13 is positioned adjacent to the internal gear 12 in the axial direction, and is positioned further towards the first open end 11a than the internal gear 12. In the radial direction, the first outer race retainer 13 is positioned radially outward from the pin groove 12a. The first outer race retaining portion 13 comprises a first stepped surface 13a and a first circumferential surface 13b. The first stepped surface 13a is formed in an annular shape, extending radially outward from the end of the internal gear 12 located on the first open end 11a side. The first circumferential surface 13b is formed to extend axially from the outer peripheral end of the first stepped surface 13a toward the first open end 11a.

[0039] The first seal portion 15 is positioned adjacent to the first outer race holding portion 13 in the axial direction, and is positioned closer to the first open end 11a than the first outer race holding portion 13. In the illustrated example, the inner diameter of the first seal portion 15 is the same as the inner diameter of the first circumferential surface 13b. Therefore, the first seal portion 15 is formed flush with the first circumferential surface 13b. The first seal portion 15 plays a role in holding the seal portion 7. The first sealing portion 15 includes the first open end 11a of the case 2. However, the first sealing portion 15 is not essential and may be omitted. In this case, for example, the first circumferential surface 13b may be used to hold the sealing portion 7.

[0040] As shown in Figures 1 and 2, the second outer race retainer 14 is positioned adjacent to the internal gear 12 in the axial direction, and is located on the second open end 11b side of the internal gear 12. In the radial direction, the second outer race retainer 14 is positioned radially outward from the pin groove 12a. The second outer race holding portion 14 may also include the second open end 11b of the case 2.

[0041] The second outer race retaining portion 14 comprises a second stepped surface 14a and a second circumferential surface 14b. The second stepped surface 14a is formed in an annular shape, extending radially outward from the end of the internal gear 12 located on the second open end 11b side. The second circumferential surface 14b is formed to extend axially from the outer peripheral end of the second stepped surface 14a toward the second open end 11b.

[0042] In this embodiment, the case where the radial length of the first stepped surface 13a and the radial length of the second stepped surface 14a are equal is used as an example for explanation. Furthermore, the case where the inner diameter of the first circumferential surface 13b and the inner diameter of the second circumferential surface 14b are the same is used as an example for explanation.

[0043] As shown in Figure 1, the carrier 3 is connected to a driven or stationary part (not shown). The carrier 3 is located radially inside the case 2. The carrier 3 rotates relative to the case 2 around the axis of the central axis O as the first oscillating gear 43 and the second oscillating gear 44, which will be described later, oscillate.

[0044] Carrier 3 comprises a first block 20 and a second block 21. The first block 20 and the second block 21 are arranged to be aligned in the axial direction. In the following explanation, the end of the carrier 3 located on the side of the first block 20 is defined as the first end 3a, and the end located on the side of the second block 21 is defined as the second end 3b. Therefore, the first end 3a and the second end 3b function as the axial ends of the entire carrier 3.

[0045] The first end 3a and the second end 3b of carrier 3 protrude axially outward from case 2. Specifically, the first end 3a of carrier 3 protrudes axially outward from the first open end 11a of case 2. Furthermore, the second end 3b of carrier 3 protrudes axially outward from the second open end 11b of case 2.

[0046] The first block 20 comprises a base 22 supported by the case 2 via a first main bearing 5, and a plurality of support columns 23 and flange portions 24 integrally molded with the base 22.

[0047] The outer shape of the base portion 22 is formed, for example, as a disc shape centered on the central axis O. The multiple support columns 23 are formed to protrude axially from the end face of the base portion 22 toward the second end 3b. The multiple support columns 23 are arranged at equal intervals in the circumferential direction. Multiple support columns 23 are inserted with some play into multiple through holes 47 formed in each of the first oscillating gear 43 and the second oscillating gear 44, which will be described later. As a result, the multiple support columns 23 connect the base 22 and the second block 21 while maintaining a non-contact state with the first oscillating gear 43 and the second oscillating gear 44.

[0048] The flange portion 24 is provided at the end of the base portion 22 located on the first end 3a side. The outer shape of the flange portion 24 is formed, for example, as a disc shape centered on the central axis O. The flange portion 24 is formed to protrude radially outward from the base portion 22. As a result, the flange portion 24 is positioned to overlap the end face of the case 2 when viewed from the axial direction. The flange portion 24 functions as a mounting surface to be attached to a driven part or a fixed part (not shown).

[0049] The outer circumferential surface 25 of the base portion 22 is formed in a multi-stage manner along the central axis O so that it serves different functions. Specifically, the outer circumferential surface 25 of the base portion 22 is formed in a multi-stage manner so that it functions as a first inner race holding portion 26 and a second sealing portion 27 provided on the first end 3a side of the first inner race holding portion 26. The first inner race retaining portion 26 holds the inner race 52 of the first main bearing 5. The seal portion 7 is located on the first end 3a side of the first inner race retaining portion 26.

[0050] The first inner race holding portion 26 comprises a first circumferential surface 26a and a first stepped surface 26b. The first circumferential surface 26a is formed in an annular shape, extending axially from the end located on the second end 3b side of the base 22 toward the first end 3a side. The first stepped surface 26b is formed in an annular shape, extending radially outward from the first circumferential surface 26a. At least a portion of the first circumferential surface 26a faces radially with respect to the first circumferential surface 13b of the first outer race holding portion 13.

[0051] The second seal portion 27 is positioned adjacent to the first inner race holding portion 26 along the axial direction. The second seal portion 27 is formed such that its outer diameter is larger than the outer diameter of the first circumferential surface 26a of the first inner race holding portion 26. The second seal portion 27 faces the first seal portion 15 in the radial direction. This allows the second seal portion 27 to cooperate with the first seal portion 15 to hold the seal portion 7.

[0052] As shown in Figures 1 and 2, the second block 21 is supported by the case 2 via the second main bearing 6. The outer shape of the second block 21 is formed, for example, as a disc shape centered on the central axis O. The second block 21 is fixed to the ends of the multiple support columns 23 by fastening members 21b. The outer circumferential surface 28 of the second block 21 is formed in a multi-stage manner along the central axis O. Specifically, the outer circumferential surface 28 of the second block 21 is formed in a multi-stage manner so as to function as the second inner race holding portion 29.

[0053] The second inner race retaining portion 29 is formed on the outer circumferential surface 28 of the second block 21, on the side of the first end 3a. The second inner race retaining portion 29 holds the inner race 62 of the second main bearing 6.

[0054] The second inner race holding portion 29 comprises a second circumferential surface 29a and a second stepped surface 29b. The second circumferential surface 29a is formed in an annular shape, extending from the end of the second block 21 located on the first end 3a side toward the second end 3b side. The second stepped surface 29b is formed in an annular shape, extending radially outward from the second circumferential surface 29a. At least a portion of the second circumferential surface 29a faces radially toward the second circumferential surface 14b of the second outer race holding portion 14.

[0055] In this embodiment, the case where the outer diameter of the first circumferential surface 26a and the outer diameter of the second circumferential surface 29a are the same is explained as an example. Furthermore, the case where the radial length of the first stepped surface 26b and the radial length of the second stepped surface 29b are equivalent is explained as an example.

[0056] (Deceleration mechanism) As shown in Figure 1, the reduction mechanism 4 comprises a drive shaft 70, a plurality of transmission gears 41, a plurality of crankshafts 42, a first oscillating gear 43, and a second oscillating gear 44.

[0057] The drive shaft 70 is, for example, positioned coaxially with the central axis O and connected to a drive source (not shown). Multiple transmission gears 41 mesh with the drive gear 70a of the drive shaft 70. Each of the multiple crankshafts 42 is connected to one of the multiple transmission gears 41. Multiple transmission gears 41 and multiple crankshafts 42 are arranged coaxially with an eccentric axis P. The eccentric axis P is arranged at equal intervals in the circumferential direction with respect to the central axis O and is parallel to the central axis O. Therefore, the multiple transmission gears 41 and multiple crankshafts 42 are arranged at equal intervals from each other in the circumferential direction.

[0058] Each crankshaft 42 is provided with a shaft portion 42a and two eccentric portions 42b. The shaft portion 42a is supported by the carrier 3. Two eccentric portions 42b are provided on the shaft portion 42a and are eccentric with respect to the eccentric axis P. The two eccentric portions 42b are formed in a circular shape and are eccentric in different directions with respect to the eccentric axis P. Each crankshaft 42 is inserted into a through hole (not shown) formed in the carrier 3 (first block 20 and second block 21). At this time, the shaft portion 42a of each crankshaft 42 is inserted into the through hole via bearings 45. The bearings 45 are positioned near both ends of the shaft portion 42a. The pair of bearings 45 support the shaft portion 42a within the through hole.

[0059] In each crankshaft 42, one of the two eccentric portions 42b is inserted via a bearing 46 into a through hole (not shown) formed in the first oscillating gear 43. The other of the two eccentric portions 42b is inserted via a bearing 46 into a through hole (not shown) formed in the second oscillating gear 44. Therefore, the first oscillating gear 43 and the second oscillating gear 44 oscillate in conjunction with the relative rotation of the two eccentric portions 42b of each crankshaft 42. This makes it possible to rotate the case 2 and the carrier 3 relative to each other.

[0060] The outer shapes of the first oscillating gear 43 and the second oscillating gear 44 are formed in a disc shape, for example, having an outer diameter smaller than the inner diameter of the internal gear 12 of the case 2. Each of the first oscillating gear 43 and the second oscillating gear 44 has the same number of through holes 47 as the number of support columns 23. Each support column 23 is inserted into each through hole 47. The inner diameter of each through hole 47 is larger than the outer diameter of each support column 23 so as not to hinder the oscillating rotation of the first oscillating gear 43 and the second oscillating gear 44.

[0061] External teeth 48 that mesh with a plurality of internal tooth pins 16 are formed on the outer circumferential surfaces of the first oscillating gear 43 and the second oscillating gear 44. The number of teeth on the external teeth 48 is formed to differ from the number of internal tooth pins 16. The first oscillating gear 43 and the second oscillating gear 44 move eccentrically together with the eccentric portion 42b as the crankshafts 42, which receive rotational driving force from the drive shaft 70, rotate. As a result, the first oscillating gear 43 and the second oscillating gear 44 rotate while engaging the external teeth 48 with the multiple internal tooth pins 16.

[0062] In this embodiment, when the case 2 is fixed to a fixed member (not shown), the first oscillating gear 43 and the second oscillating gear 44 rotate together with the carrier 3 around the central axis O relative to the case 2. In contrast, when the carrier 3 is fixed to a fixed member (not shown), the first oscillating gear 43 and the second oscillating gear 44 rotate together with the case 2 around the central axis O relative to the carrier 3.

[0063] The seal portion 7 is formed, for example, in an annular shape and is positioned radially sandwiched between the first seal portion 15 and the second seal portion 27. The seal portion 7 seals the annular space formed between the case 2 and the carrier 3. The seal portion 7 prevents foreign matter from entering the annular space from the outside, and also prevents liquid lubricant or the like stored in the annular space from flowing out to the outside.

[0064] (Main bearing) As shown in Figure 1, the first main bearing 5 and the second main bearing 6 are tapered roller bearings. The first main bearing 5 is positioned between the case 2 and the base 22 of the first block 20 of the carrier 3. The first main bearing 5 comprises an outer race 51, an inner race 52, a plurality of rollers (an example of rolling elements according to the present invention) 53, and a retainer 54.

[0065] The inner race 52 is located radially inside the outer race 51. Multiple rollers 53 are arranged to roll between the outer race 51 and the inner race 52. The retainer 54 is located between the outer race 51 and the inner race 52.

[0066] The outer race 51 is formed in an annular shape with the central axis O as its center. The outer race 51 contacts the first stepped surface 13a of the first outer race holding portion 13 from the axial outside (first open end 11a side) and is fitted into the first circumferential surface 13b of the first outer race holding portion 13.

[0067] The outer race 51 is provided with an outer ring raceway surface (an example of a rolling surface according to the present invention) 51a on its inner circumferential surface. The outer ring raceway surface 51a is inclined with respect to the central axis O. The outer ring raceway surface 51a is inclined radially outward as it moves axially outward (towards the first open end 11a). The outer ring raceway surface 51a is formed in a conical shape that is inclined to move away from the central axis O as it moves axially from the first stepped surface 13a towards the first open end 11a. Therefore, the inner diameter of the outer ring raceway surface 51a becomes smaller as it approaches the first stepped surface 13a, and larger as it approaches the first open end 11a.

[0068] The outer race 51 is equipped with a flange portion 51b. The flange portion 51b is positioned radially outward from each roller 63 and is formed to protrude from the outer ring raceway surface 51a toward the roller axis (an example of an axis according to the present invention) R1. The flange portion 51b supports each roller 53 by contacting the end face 53a of each roller 53. More specifically, the flange portion 51b restricts the movement of each roller 53 in the direction along the roller axis R1. In this way, the flange portion 51b holds the position of each roller 53 in a predetermined position on the outer ring raceway surface 51a.

[0069] The outer shape of the inner race 52 is formed as an annular shape coaxial with the outer race 51. The inner race 52 is held by the first inner race holding portion 26 of the base portion 22. Specifically, the inner race 52 contacts the first stepped surface 26b from the axial inner side (second end 3b side) and is fitted into the first circumferential surface 26a.

[0070] The inner race 52 has an inner ring raceway surface (rolling surface) 52a on its outer circumference. The inner ring raceway surface 52a is inclined to face the outer ring raceway surface 51a of the outer race 51 across the roller axis R1. The inner ring raceway surface 52a is formed in a conical shape that inclins away from the central axis O as it moves from the second end 3b toward the first step surface 26b in the axial direction. Therefore, the inner diameter of the inner ring raceway surface 52a becomes smaller as it approaches the second end 3b, and larger as it approaches the first step surface 26b.

[0071] Each roller 53 is a conical roller with an outer shape formed in the shape of a truncated cone. Each roller 53 is arranged to roll between the outer ring raceway surface 51a of the outer race 51 and the inner ring raceway surface 52a of the inner race 52. When viewed from the axial direction, each roller 53 is arranged at equal intervals in the circumferential direction so as to be arranged radially with respect to the central axis O. Each roller 53 is arranged such that the end face 53a on the larger diameter side of both ends along the roller axis R1 faces the first open end 11a.

[0072] Each roller 53 rolls on the outer raceway surface 51a of the outer race 51 and on the inner raceway surface 52a of the inner race 52, while rotating circumferentially around the central axis O.

[0073] The retainer 54 holds multiple rollers 53. The retainer 54 comprises a first annular portion and a second annular portion extending in the circumferential direction, and a plurality of connecting portions connecting the first annular portion and the second annular portion. The first and second annular sections are configured to correspond to the first and second annular sections 65 and 66 of the second main bearing 6, which will be described later. Furthermore, the connecting section is configured to correspond to the connecting section 67 of the second main bearing 6, which will be described later. Therefore, a detailed explanation of the first annular section, the second annular section, and the connecting section of the cage 54 of the first main bearing 5 will be omitted.

[0074] As shown in Figures 1 and 2, the second main bearing 6 is positioned between the case 2 and the second block 21 of the carrier 3. The second main bearing 6 comprises an outer race 61, an inner race 62, a plurality of rollers (an example of rolling elements according to the present invention) 63, and a retainer 64.

[0075] The inner race 62 is positioned radially inward of the outer race 61. Multiple rollers 63 are rotatably arranged between the outer race 61 and the inner race 62. A retainer 64 is positioned between the outer race 61 and the inner race 62.

[0076] The outer race 61 has an annular shape centered on the central axis O. The outer race 61 has an end face 61d that is in contact with the second stepped surface 14a of the second outer race holding portion 14 from the axial outside (second open end 11b side), and the outer circumferential surface 61e is fitted to the second circumferential surface 14b of the second outer race holding portion 14. Therefore, the outer circumferential surface 61e of the outer race 61 is in contact with the second circumferential surface 14b.

[0077] The outer race 61 is provided with an outer ring raceway surface (an example of a rolling surface according to the present invention) 61a as its inner circumferential surface. The outer ring raceway surface 61a is inclined with respect to the central axis O. The outer ring raceway surface 61a is inclined radially outward as it moves axially outward (towards the second open end 11b). The outer ring raceway surface 61a is formed in a conical shape that is inclined to move away from the central axis O as it moves axially from the second stepped surface 14a towards the second open end 11b. Therefore, the inner diameter of the outer ring raceway surface 61a becomes smaller as it approaches the second stepped surface 14a, and larger as it approaches the second open end 11b.

[0078] The outer race 61 is equipped with a flange portion 61b. The flange portion 61b is positioned radially outward from each roller 63 and is formed to protrude from the outer ring raceway surface 61a toward the roller axis (an example of an axis according to the present invention) R2. The flange portion 61b supports each roller 63 by contacting the end face 63a of each roller 63. More specifically, the flange portion 61b maintains the position of each roller 63 at a predetermined position on the outer ring raceway surface 61a by restricting the movement of each roller 63 in the direction along the roller axis R2.

[0079] The outer shape of the inner race 62 is formed as an annular shape coaxial with the outer race 61. The inner race 62 is held in the second inner race holding portion 29. Specifically, the inner race 62 contacts the second stepped surface 29b from the axial inner side (first end 3a side) via the spacer 69 and is fitted into the second circumferential surface 29a.

[0080] The spacer 69 is formed in an annular shape with respect to the central axis O. The inner diameter of the spacer 69 is equal to or slightly larger than the outer diameter of the second circumferential surface 29a. The outer diameter of the spacer 69 is equal to or slightly smaller than the outer diameter of the outer circumferential surface 28 of the second block 21. In the illustrated example, the spacer 69 is shown as having an inner diameter slightly larger than the outer diameter of the second circumferential surface 29a, and an outer diameter slightly smaller than the outer diameter of the outer circumferential surface 28 of the second block 21.

[0081] The spacer 69 is positioned axially sandwiched between the inner race 62 and the second block 21. The spacer 69 plays a role in applying preload to the first main bearing 5 and the second main bearing 6. Therefore, by adjusting the thickness of the spacer 69 through replacement work or other means, it becomes possible to adjust the preload of the first main bearing 5 and the second main bearing 6.

[0082] The inner race 62 has an inner ring raceway surface (rolling surface) 62a on its outer circumference. The inner ring raceway surface 62a is inclined to face the outer ring raceway surface 61a of the outer race 61 across the roller axis R2. The inner ring raceway surface 62a is formed in a conical shape that inclins away from the central axis O as it moves from the first end 3a toward the second step surface 29b in the axial direction. Therefore, the inner diameter of the inner ring raceway surface 62a becomes smaller as it approaches the first end 3a, and larger as it approaches the second step surface 29b.

[0083] Each roller 63 is a conical roller with an outer shape formed in the shape of a truncated cone. The roller axis R2 of each roller 63 is inclined at a predetermined angle in the opposite direction to that of each roller 53 of the first main bearing 5 with respect to the axial direction. Each roller 63 is positioned between the outer ring raceway surface 61a of the outer race 61 and the inner ring raceway surface 62a of the inner race 62.

[0084] As shown in Figures 2 and 3, each roller 63 is arranged at equal intervals in the circumferential direction so as to be arranged radially around the central axis O when viewed from the axial direction. Figure 3 is an enlarged perspective view of the area around the end face 63a of the roller 63 of the second main bearing 6 shown in Figure 2. Note that the cage 64 is not shown in Figure 3. Each roller 63 is positioned such that the end face 63a of the larger diameter portion of both ends along the roller axis R2 faces the second open end 11b. Each roller 63 rolls on the outer ring raceway surface 61a of the outer race 61 and on the inner ring raceway surface 62a of the inner race 62, while rotating circumferentially around the central axis O.

[0085] The retainer 64 holds multiple rollers 63. The retainer 64 comprises a first annular portion 65 and a second annular portion 66 extending in the circumferential direction, and a plurality of connecting portions 67 connecting the first annular portion 65 and the second annular portion 66.

[0086] The first annular portion 65 extends circumferentially along the end face of the multiple rollers 63 that is opposite to the end face 63a. The second annular portion 66 is positioned on the opposite side of the first annular portion 65, with the multiple rollers 63 in between, and extends circumferentially along the end face 63a of the multiple rollers 63.

[0087] Each connecting portion 67 extends radially when viewed from the axial direction. Multiple connecting portions 67 are arranged at predetermined intervals in the circumferential direction. Each connecting portion 67 extends between the outer ring raceway surface 61a of the outer race 61 and the inner ring raceway surface 62a of the inner race 62, and connects the first annular portion 65 and the second annular portion 66 along the roller axis R2. Each connecting portion 67 is positioned at a distance from the outer ring raceway surface 61a and the inner ring raceway surface 62a, respectively.

[0088] The retainer 64 has pockets surrounded by a first annular portion 65, a second annular portion 66, and a pair of circumferentially adjacent connecting portions 67. Thus, each pocket is spaced apart along the circumferential direction. Each roller 63 is held within each pocket so as to be able to roll.

[0089] The first main bearing 5 and the second main bearing 6 will be explained in more detail. The first main bearing 5 and the second main bearing 6 are arranged almost symmetrically in the axial direction and have substantially the same configuration. Therefore, in this embodiment, the second main bearing 6 will be described in detail.

[0090] As shown in Figures 1 and 2, the flange portion 61b of the outer race 61 restricts the movement of each roller 63 along the roller axis R2 by contacting the end face 63a of each roller 63. The flange portion 61b has a flange surface 61b1 that contacts the end face 63a of each roller 63. In this embodiment, the intersection point (virtual intersection point) where the outer raceway surface 61a of the outer race 61 and the flange surface 61b1 of the flange portion 61b are intersected is defined as intersection point 61p. Intersection point 61p is located at the base portion 61f, which is a thinned portion of the flange portion 61b.

[0091] Furthermore, as shown in Figures 2 and 3, the flange portion 61b is formed to protrude from the outer ring raceway surface 61a toward the roller axis R2 so as to cover more than 20% of the maximum diameter of each roller 63 when viewed from the direction along the roller axis R2, and contacts the end face 63a of the roller 63 via the flange surface 61b1. Therefore, the flange portion 61b is formed such that, when viewed from the direction along the roller axis R2, the distance between the roller axis R2 and the flange portion 61b along the end face 63a is less than 30% of the maximum diameter of the roller 63.

[0092] As shown in Figure 2, the flange portion 61b is not formed so that the entire flange surface 61b1 contacts the end surface 63a, but rather the flange surface 61b1 contacts only the portion of the end surface 63a located near the roller axis R2. Therefore, the flange portion 61b is formed so that the flange surface 61b1 does not contact the portion of the end surface 63a located on the outer peripheral edge side of the roller 63. Specifically, the base portion 61f of the flange portion 61b has a relief portion 68 formed therein to avoid contact with the portion of the end face 63a located on the outer peripheral edge side of the roller 63. The relief portion 68 is formed to be semicircular indented outward in the radial direction when viewed in a longitudinal section. This makes it possible to bring the flange surface 61b1 into contact with the portion of the end face 63a located near the roller axis R2.

[0093] (Support tube) As shown in Figure 2, case 2 is equipped with a support cylinder 2g that covers the outer race 61 of the second main bearing 6 from the radial outside. The support cylinder 2g is formed to extend outward along the axial direction, away from the first oscillating gear 43 and the second oscillating gear 44 (towards the second end 3b of the carrier 3), and is formed in a cylindrical shape having an inner circumferential surface and an outer circumferential surface 2g1. In particular, the inner circumferential surface of the support cylinder 2g functions as the second circumferential surface 14b of the second outer race holding portion 14. Therefore, the support cylinder 2g having the second circumferential surface 14b constitutes a part of the second outer race holding portion 14.

[0094] The support tube 2g is formed to cover the outer race 61 from the radial outside and to cover the intersection 61p at least from the radial side. In the illustrated example, the support tube 2g extends axially so as to project outward from the outer end surface 61c of the outer race 61. Thus, the support tube 2g covers the entire outer race 61 from the radial outside. Furthermore, the support tube 2g is in gapless contact with the outer peripheral surface 61e of the outer race 61 along its entire length.

[0095] As a result, the entire outer race 61 is held from the radial outside by the support cylinder 2g (second outer race holding part 14). In particular, the support cylinder 2g covers the intersection 61p located at the base portion 61f of the flange portion 61b, which is considered a thin-walled portion, from the radial outside. Therefore, the support cylinder 2g is able to suppress unintended displacement (give) such as bending radially outward of the flange portion 61b. This allows the support cylinder 2 to function as a backup member that reinforces the rigidity of the flange portion 61b.

[0096] Furthermore, the support cylinder 2g extends axially with a constant wall thickness H1 (first length according to the present invention). Therefore, the wall thickness H1 of the support cylinder 2g is constant over the entire length of the support cylinder 2g. Note that the wall thickness H1 of the support cylinder 2g corresponds to the radial distance between the inner circumferential surface, the second circumferential surface 14b, and the outer circumferential surface 2g1. In particular, the wall thickness H1 of the support cylinder 2g is formed to be longer (larger) than the radial distance H2 (second length according to the present invention) between the outer circumferential surface 61e of the outer race 61 and the intersection point 61p.

[0097] Corresponding to the support cylinder 2g configured as described above, as shown in Figure 1, the portion of case 2 that surrounds the first main bearing 5 and the seal portion 7 from the radial outside functions as a support cylinder 2h. Therefore, the support cylinder 2h, including the flange portion 51b, covers the entire outer race 51 of the first main bearing 5 from the radial outside and also constitutes a part of the first outer race holding portion 13. The support cylinder 2h has a relationship with the first main bearing 5 similar to the relationship between the support cylinder 2g and the second main bearing 6.

[0098] (Operation of gear mechanisms) Next, we will explain the operation of the gear mechanism 1 configured as described above. We will focus particularly on the second main bearing 6. In the gear apparatus 1 of this embodiment, the flange surface 61b1 of the flange portion 61b formed on the outer race 61 is in contact with the end face 63a of each roller 63, thereby restricting unintended movement of each roller 63 in the direction along the roller axis R2. As a result, multiple rollers 63 can be stably rolled around the roller axis R2 between the inner race 62 and the outer race 61, and the operational reliability of the second main bearing 6 can be maintained. This allows the case 2 and the carrier 3 to rotate relative to each other stably around the central axis O.

[0099] In particular, Case 2 has a support cylinder 2g that surrounds the outer race 61 from the radial outside around its entire circumference. Moreover, the support cylinder 2g covers at least from the radial outside the virtual intersection point 61p where the outer ring rolling surface 61a and the flange surface 61b1 of the flange portion 61b intersect. Therefore, the support cylinder 2g can cover the base portion (thin-walled portion) 61f of the flange portion 61b located near the intersection point 61p from the radial outside. As a result, the support cylinder 2g can be used to suppress unintended displacement (give) such as deflection of the flange portion 61b toward the radial outside.

[0100] Therefore, even if, for example, a moment load acts on the second main bearing 6 during the operation of the gear unit 1, causing the flange portion 61b to attempt to displace radially outward from the root portion 61f, the displacement of the flange portion 61b can be suppressed by utilizing the support cylinder 2g, which functions as a backup member. As a result, a gear unit 1 with sufficient moment rigidity can be achieved. Specifically, it is possible to increase the moment rigidity [Nm / arc.min.] of the gear unit 1 by approximately 5% to 20%.

[0101] Based on the above, the gear device 1 of this embodiment can maintain sufficient moment rigidity while restricting the movement of multiple rollers 63 along the roller axis R2.

[0102] The moment stiffness in the gear unit 1 is the moment load value required to tilt the carrier 3 by a unit angle relative to the case 2, and a larger value indicates higher stiffness. Specifically, the moment stiffness in the gear unit 1 is defined as "△M / △θ" in relation to the moment △M that tries to return the axis of the carrier 3 to the direction of the central axis O of the case 2 when the axis of the carrier 3 is tilted at an angle △θ with respect to the central axis O of the case 2.

[0103] In order to support the carrier 3 against centrifugal forces acting unbalanced on it, and inertial forces such as vibrations acting from the outside, it is necessary to consider not only the balance of radial forces but also the balance of moments in the first main bearing 5 and the second main bearing 6. In this case, the balance of moments and forces is maintained by the bearing rigidity of the first main bearing 5 and the second main bearing 6.

[0104] Moment stiffness is measured, for example, by the axial loading method shown in Figure 4, or the radial loading method shown in Figure 5. Figure 4 illustrates the measurement method of moment stiffness using the axial loading method. Figure 5 illustrates the measurement method of moment stiffness using the radial loading method.

[0105] When measuring moment stiffness, as shown in Figures 4 and 5, for example, with the case 2 of the gear unit 1 fixed to the fixing part S1, a rod-shaped measuring part S2 is attached to the carrier 3. Next, an axial load F is applied to the tip of the measuring part S2, and the displacement on the outer circumference of the case 2 is measured by a displacement meter S4 (see Figure 4). Alternatively, a radial load F is applied to the tip of the measuring part S2, and the displacement near the outer circumference of the carrier 3 is measured by a displacement meter S4 (see Figure 5). In this case, the moment △M can be calculated based on the axial load F and the distance L (the distance between the point of application of the axial load F and the center point of case 2 or carrier 3). Additionally, the angle △θ can be calculated based on the measurement value from the displacement sensor S4 and the distance I (the distance between the displacement sensor S4 and the center point of case 2 or carrier 3). Using the method described above, it becomes possible to measure the moment stiffness of the gear mechanism 1.

[0106] Furthermore, in the gear device 1 of this embodiment, as shown in Figure 2, the support cylinder 2g covers the entire outer race 61, including the flange portion 61b, from the radial outside. This effectively suppresses unintended deflection and other displacements of the flange portion 61b, as well as radial outward displacement of the entire outer race 61. Therefore, the moment rigidity of the gear device 1 can be further improved. In addition, since the support tube 2g covers the outer race 61 from the radial outside while in contact with the outer peripheral surface 61e of the outer race 61, the above-mentioned effects can be achieved even more effectively.

[0107] Furthermore, since the wall thickness H1 of the support cylinder 2g is greater than the radial distance H2 between the outer peripheral surface 61e of the outer race 61 and the intersection point 61p, sufficient rigidity of the support cylinder 2g can be ensured. Therefore, the support cylinder 2g can be used to absorb unintended deflection and other displacements of the flange portion 61b, and the displacement of the flange portion 61b and the outer race 61 as a whole can be effectively suppressed.

[0108] Furthermore, in this embodiment, when considering the contact resistance between the flange portion 61b and the roller 63, the contact resistance tends to increase as the contact area of ​​the flange surface 61b1 with respect to the end face 63a increases. This leads to an increase in the rotational resistance of the roller 63. Therefore, in order to improve the rotational performance of the roller 63, it is preferable to minimize the contact area between the flange portion 61b and the end face 63a. Furthermore, focusing on the moment resistance acting on the roller 63, the smaller the distance between the roller axis R2 and the flange 61b at the end face 63a, the smaller the moment resistance from the flange 61b that hinders the rotation of the roller 63. The magnitude of the moment resistance is determined by the distance between the roller axis R2 and the flange 61b. Therefore, when the moment resistance on the roller 63 is small, the rotational performance of the roller 63 improves, similar to when the contact resistance on the roller 63 is suppressed.

[0109] Furthermore, if the end face 63a is a convex curved surface rather than a flat surface, the contact area of ​​the flange surface 61b1 that contacts the end face 63a can be reduced. As a result, the contact resistance between the roller 63 and the flange portion 61b can be reduced, which reduces the rotational resistance of the roller 63 and improves the rotational performance of the roller 63.

[0110] By utilizing the above-mentioned requirements in combination, the rotational resistance of roller 63 can be reduced, leading to improved rotational performance. In this regard, in this embodiment, the flange portion 61b is formed to be long enough to cover more than 20% of the maximum diameter of the roller 63 when viewed from the direction along the roller axis R2, so that it can contact the end face 63a of the roller 63 via the flange surface 61b1 at a position close to the roller axis R2. Furthermore, the flange portion 61b is kept non-contact with the portion of the end face 63a located on the outer peripheral edge side by the relief portion 68.

[0111] Therefore, the rotational resistance when the roller 63 begins to roll can be reduced, and the starting torque (startup torque) can be reduced. Consequently, the initial drive of the second main bearing 6 can be stabilized, and the rotational performance and operational reliability of the second main bearing 6 can be improved. As a result, the starting torque and drive torque of the gear unit 1 can be stabilized.

[0112] Furthermore, in this embodiment, unlike conventional main bearings in which a flange portion 61b is formed on the inner race 62, the flange portion 61b is formed on the outer race 61. Therefore, the spacer 69 can be replaced while suppressing the application of external forces to the flange portion 61b. For example, when replacing the spacer 69, even if the inner race 62 is held down with a jig or the like and the case 2 and the second main bearing 6 are temporarily assembled, it is difficult for external forces to act on the flange portion 61b formed on the outer race 61. Therefore, the spacer 69 can be replaced without requiring excessive attention to the flange portion 61b. Consequently, the preload adjustment of the second main bearing 6 using the spacer 69 can be performed efficiently.

[0113] In particular, the outer diameter of the inner race 62 of the second main bearing 6 is larger than the outer diameter of the second block 21 that constitutes the carrier 3. Therefore, the outer circumferential surface 62c of the inner race 62 protrudes radially outward from the outer circumferential surface 28 of the second block 21. Consequently, when viewed from the axial direction, a portion of the inner race 62 can be exposed radially outward from the outer circumferential surface 28 of the second block 21, and that portion can be seen.

[0114] Therefore, before removing the second block 21, the portion of the inner race 62 that is exposed radially outward from the outer circumferential surface 28 of the second block 21 can be held down using a jig or the like. This allows the case 2 and the second main bearing 6 to be maintained in a temporarily assembled state. As a result, it is possible to prevent the second main bearing 6 from unintentionally disassembling when the second block 21 is removed. Therefore, the spacer 69 can be easily replaced, and the preload of the second main bearing 6 can be easily and smoothly adjusted.

[0115] (Confirmation test) Next, we will describe a moment stiffness verification test performed as a specific example of a gear device according to the present invention. In this verification test, the moment stiffness of the gear assembly 1 of this embodiment shown in Figures 1 to 3 was measured. The moment stiffness was measured using the method shown in Figures 4 and 5. In this verification test, seven gear assembly 1s were prepared, each with a different outer diameter (outer diameter of case 2), and the moment stiffness was measured for each. The seven gear assembly 1s differed only in their outer diameters; all other components were identical.

[0116] Figure 6 shows the results of measuring the moment stiffness of seven gear units 1 with different outer diameters. In Figure 6, the moment stiffness measured for each of the seven gear units 1 is indicated by a circle ("○"). As shown in Figure 6, it can be seen that the moment stiffness of the gear unit 1 increases as the outer diameter increases.

[0117] Furthermore, in this verification test, as comparative examples of the present invention, seven gear units were prepared in which the flange portion 61b was formed on the inner race (for example, the inner race 62 of the second main bearing 6) instead of the outer race (for example, the outer race 61 of the second main bearing 6), as in the conventional method. The moment stiffness was also measured for these seven gear units. In Figure 6, the moment stiffness measured for each of the seven comparative gear units is indicated by the "◇" mark.

[0118] As shown in Figure 6, it was confirmed that the seven comparative gear systems all exhibited lower moment stiffness compared to the gear system 1 of this embodiment, which is an example, for the same outer diameter. Specifically, the gear system 1 of this embodiment showed a moment stiffness increase of at least 105% and up to 117% compared to the conventional gear system used as a comparative example.

[0119] Therefore, as in this embodiment, when a flange portion 61b is formed on the outer race 61, the outer race 61 is surrounded from the radial outside using the support cylinder 2g of the case 2, and the intersection point 61p between the flange surface 61b1 and the outer ring raceway surface 61a is covered from at least the radial outside, it was confirmed that the moment rigidity of the gear device 1 actually increases by at least 5%. Therefore, we were able to confirm that by using the support cylinder 2g in Case 2, unintended displacement of the flange portion 61b can be suppressed, leading to an improvement in moment rigidity.

[0120] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Embodiments and their modifications include, for example, those that can be easily imagined by those skilled in the art, those that are substantially the same, and those that are equivalent.

[0121] For example, in the above embodiment, the case was described in which the reduction mechanism 4 oscillates and rotates the first oscillating gear 43 and the second oscillating gear 44 by a crankshaft 42 that rotates around an eccentric axis P. However, the configuration is not limited to this. For example, the reduction mechanism 4 may include an input shaft 80 (see the dashed line in Figure 1) that is arranged coaxially with the central axis O and has multiple eccentric portions 42b, instead of the drive shaft 70, drive gear 70a, transmission gear 41, and multiple crankshafts 42. In this case, instead of the first oscillating gear 43 and the second oscillating gear 44, it may be provided with multiple oscillating gears that oscillate in conjunction with the rotation of the multiple eccentric portions 42b. Even with this configuration, the same effects as in the above embodiment can be achieved.

[0122] Furthermore, in the above embodiment, the example given was that the support cylinder 2g constituting the second outer race holding portion 14 covers the entire outer race 61 of the second main bearing 6 from the radial outside, but the embodiment is not limited to this case. For example, the support cylinder 2g only needs to be formed to cover at least the intersection 61p from the radial outside. Furthermore, the second circumferential surface 14b, which is the inner circumferential surface of the support cylinder 2g, does not necessarily need to be in contact with the outer circumferential surface 61e of the outer race 61. As long as the support cylinder 2g covers the outer race 61 from the radial outside, a small gap may be formed between the second circumferential surface 14b and the outer circumferential surface 61e of the outer race 61.

[0123] Furthermore, although the above embodiment was described using a configuration with a spacer 69 as an example, the spacer 69 is not essential and may be omitted.

[0124] Furthermore, in the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective.

[0125] Furthermore, the present invention includes the following embodiments. <1> A case that is rotatably positioned around a central axis, A carrier is arranged radially inside the case so as to be rotatable relative to the central axis, The case or carrier is provided with a gear mechanism that transmits rotation from an external source at a reduced speed, A main bearing is disposed between the case and the carrier, The main bearing is, An inner race provided on the carrier, An outer lace provided in the aforementioned case, The system comprises a plurality of rolling elements that are rotatably held between the inner race and the outer race and rotate around an axis inclined with respect to the central axis, The outer race is provided with a flange portion that restricts the movement of the plurality of rolling elements in the direction along the axis, The flange portion is positioned radially outward from the plurality of rolling elements and is formed to protrude toward the axis from the rolling surface of the outer race. Furthermore, the flange portion has a flange surface that contacts the end faces of the multiple rolling elements. The case comprises a support cylinder that extends along the central axis and covers the outer race from the radially outer side. The gear apparatus is characterized in that the support cylinder covers the intersection point where the rolling surface and the flange surface intersect from at least the radially outer side. <2> The support cylinder extends along the central axis to at least reach the outer end surface of the outer race, and covers the entire outer race from the radial outside. <1> The gear mechanism described above. <3> Viewed from a direction along the axis of the rolling element, the flange is formed to protrude toward the axis from the rolling surface so as to cover 20% or more of the diameter of the rolling element, and is in contact with the end face of the rolling element via the flange surface. <1> or <2> The gear mechanism described above. <4> The flange surface is not in contact with the portion of the end face of the rolling element that is located on the outer peripheral edge side of the rolling element. <3> The gear mechanism described above. <5> The support cylinder is in contact with the outer surface of the outer race. <1> from <4> A gear mechanism as described in any one of the following. <6> The support cylinder is formed such that its first length along the radial direction is longer than its second length along the radial direction between the outer circumferential surface of the outer race and the intersection point. <5> The gear mechanism described above. <7> The inner race is formed with an outer diameter larger than the outer diameter of the carrier. A portion of the inner race is exposed radially outward from the outer surface of the carrier when viewed from a direction along the central axis. <1> from <6> A gear mechanism as described in any one of the following. [Explanation of symbols]

[0126] O…Central axis line H1...Wall thickness of the support tube (first length) H2…Second length R1, R2... Roller axis (axis of the rolling element) 1... Gear system 2…case 2g, 2h... support tube 3… Career 4…Reduction mechanism (gear mechanism) 5…First main bearing (main bearing) 6…Second main bearing (main bearing) 51, 61… Outer lace 51a, 61a... Outer ring raceway surface (rolling surface) 51b,61b…Tsubabe 52, 62… Inner lace 53, 63... (rolling body) 53a, 63a... end faces 61b1…Tsubamen 61e...Outer surface of the outer race 61p…intersection

Claims

1. A case that is rotatably positioned around a central axis, A carrier is arranged radially inside the case so as to be rotatable relative to the central axis, The case or carrier is provided with a gear mechanism that transmits rotation from an external source at a reduced speed, A main bearing is disposed between the case and the carrier, The main bearing is, An inner race provided on the carrier, An outer lace provided in the aforementioned case, The system comprises a plurality of rolling elements that are rotatably held between the inner race and the outer race and rotate around an axis inclined with respect to the central axis, The outer race is provided with a flange portion that restricts the movement of the plurality of rolling elements in the direction along the axis, The flange portion is positioned radially outward from the plurality of rolling elements and is formed to protrude toward the axis from the rolling surface of the outer race. Furthermore, the flange portion has a flange surface that contacts the end faces of the multiple rolling elements. The case comprises a support cylinder that extends along the central axis and covers the outer race from the radially outer side. The gear apparatus is characterized in that the support cylinder covers the intersection point where the rolling surface and the flange surface intersect from at least the radially outer side.

2. The gear apparatus according to claim 1, wherein the support cylinder extends along the central axis to at least reach the outer end surface of the outer race and covers the entire outer race from the radially outside.

3. The gear apparatus according to claim 1 or 2, wherein, when viewed from a direction along the axis of the rolling element, the flange is formed to protrude toward the axis from the rolling surface so as to cover 20% or more of the diameter of the rolling element, and contacts the end face of the rolling element via the flange surface.

4. The gear apparatus according to claim 3, wherein the flange surface is not in contact with the portion of the end face of the rolling element that is located on the outer peripheral edge side of the rolling element.

5. The gear apparatus according to claim 1 or 2, wherein the support cylinder is in contact with the outer circumferential surface of the outer race.

6. The gear apparatus according to claim 5, wherein the support cylinder is formed such that the first length along the radial direction is longer than the second length along the radial direction between the outer circumferential surface of the outer race and the intersection point.

7. The inner race is formed with an outer diameter larger than the outer diameter of the carrier. The gear apparatus according to claim 1 or 2, wherein a portion of the inner race is exposed radially outward from the outer surface of the carrier when viewed from a direction along the central axis.

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