gear arrangement

Abstract

In the gear device (1) of the present application, the outer ring (61) of the second main bearing (6) has a flange portion (61b) that restricts movement of a plurality of rollers (rolling elements) (63) in a direction along a roller axis (R2). The flange portion is disposed at a position on an outer side in a radial direction from the rolling elements, and is formed so as to protrude from an outer ring raceway surface (rolling surface) (61a) toward the roller axis. Furthermore, the flange portion has a flange surface (61b1) that contacts an end surface (63a) of the roller. The housing (2) has a support cylinder (2g) that covers the outer ring from an outer side in the radial direction. The support cylinder covers at least an intersection point (61p) at which the outer ring raceway surface and the flange surface intersect, from the outer side in the radial direction.

Description

Technical Field

[0001] This invention relates to gear mechanisms. Background Technology

[0002] In gear mechanisms such as gearboxes, where the gear carrier is rotatably mounted in the housing by bearings, tapered roller bearings are sometimes used as bearings. Tapered roller bearings are suitable for applications subjected to heavy loads, impact loads, and other similar conditions.

[0003] Tapered roller bearings have an inner ring, an outer ring, and multiple cylindrical rollers disposed between the inner and outer rings. The cylindrical rollers are formed in a cylindrical shape and are arranged with their axes (roller axes) inclined relative to the axes (main axes) of the housing and gear carrier.

[0004] As such tapered roller bearings, there are known bearings in which the outer ring bearing housing surface is bent into a cross-sectional shape resembling the letter S (the letter S-shaped trajectory) and an undercut guide is provided in the cage (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.

[0005] Furthermore, another type of tapered roller bearing, known for example, has a flange on the inner ring. In this case, the flange is used to restrict the movement of the cylindrical rollers along the roller axis.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 2021-517223 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In transmissions equipped with tapered roller bearings, a spacer for adjusting preload is sometimes placed between the inner ring of the tapered roller bearing and the gear carrier.

[0011] In this case, preload adjustment can be performed by replacing the spacer used for preload adjustment while disassembling and assembling the transmission. Specifically, the spacer is replaced while disassembling the transmission by loosening the fasteners of the gear carrier, and then the gear carrier is reassembled by tightening the fasteners.

[0012] At this point, when using conventional tapered roller bearings with flanges formed on the inner ring, a structure is known where the flange protrudes radially outward from the outer periphery of the gear carrier toward the main axis to facilitate replacement of the spacer. This is because, when replacing the spacer, the transmission housing and the tapered roller bearing can be temporarily assembled together, for example, by pressing the flange using a jig. This allows for easy removal of the gear carrier from the tapered roller bearing for spacer replacement.

[0013] However, in this case, the flange formed on the inner ring protrudes radially outward from the outer circumference of the gear carrier. Therefore, the flange is exposed to the outside of the gear carrier. Consequently, the flange is not surrounded by the gear carrier and is not supported by it.

[0014] Therefore, when a torque load is applied to a tapered roller bearing, unexpected deformations such as deflection at the root (thin-walled portion) of the flange can easily occur. Consequently, this may lead to a reduction in the torque stiffness of the transmission.

[0015] The purpose of this invention is to provide a gear device that can maintain sufficient moment stiffness while restricting the movement of the roller along the axis.

[0016] Solution for solving the problem

[0017] (1) A gear device according to a technical solution of the present invention is characterized by comprising: a housing configured to be rotatable about a central axis; a gear carrier configured to be rotatable relative to the central axis on the radially inner side of the housing; a gear mechanism that decelerates rotation from the outside and transmits it to the housing or the gear carrier; and a main bearing configured between the housing and the gear carrier. The main bearing comprises: an inner ring disposed on the gear carrier; an outer ring disposed on the housing; and a plurality of rolling elements held between the inner ring and the outer ring in a rollable manner, rotating about an axis inclined relative to the central axis. The outer ring has a flange portion that restricts the movement of the plurality of rolling elements in a direction along the axis. The flange portion is disposed at a position further outward in the radial direction than the plurality of rolling elements and is formed to protrude from the rolling surface of the outer ring toward the axis. Moreover, the flange portion has a flange surface that contacts the end faces of the plurality of rolling elements. The housing comprises a support cylinder that extends along the central axis and covers the outer ring from the radially outer side. The support cylinder covers at least the intersection of the rolling surface and the flange surface from the radially outer side.

[0018] According to the gear mechanism of the present invention, since the flange surface of the flange portion formed on the outer ring contacts the end faces of the multiple rolling elements, accidental movement of the rolling elements in the direction along the axis can be restricted. Therefore, the multiple rolling elements can roll stably about the axis between the inner and outer rings, maintaining the operational reliability of the main bearing. Consequently, the housing and gear carrier can rotate stably relative to each other about the central axis.

[0019] In particular, the housing has a support cylinder that surrounds the outer ring radially outward over its entire circumference. Furthermore, the support cylinder covers at least radially outward the imaginary intersection point where the rolling surface of the outer ring intersects with the flange surface of the flange portion. Therefore, the support cylinder can cover the root portion (thin-walled portion) of the flange portion near the intersection point radially outward. This allows the support cylinder to suppress unexpected displacements (retraction) such as radial outward deflection of the flange portion. Consequently, the support cylinder can function as a support member that strengthens the rigidity of the flange portion.

[0020] Therefore, during the operation of the gear assembly, even if the flange needs to displace radially outward from its root point due to a torque load acting on the main bearing, for example, the support sleeve can suppress the displacement of the flange. As a result, a gear assembly with sufficient torque stiffness can be achieved. Furthermore, torque stiffness refers to the torque load value required to tilt the gear carrier relative to the housing by a unit angle; a larger value indicates higher stiffness.

[0021] Furthermore, unlike conventional main bearings where a flange is formed on the inner ring, a flange is formed on the outer ring. Therefore, even when a spacer is provided between the inner ring and the gear carrier, the spacer can be replaced while suppressing external forces acting on the flange. For example, when replacing the spacer, even when the housing and main bearing are temporarily assembled together by pressing the inner ring with a jig, external forces are unlikely to act on the flange formed on the outer ring. Therefore, the spacer can be replaced without requiring excessive attention to the flange. Thus, the preload adjustment of the main bearing utilizing the spacer can be performed efficiently.

[0022] (2) Alternatively, the support cylinder may extend at least along the central axis to the outer end face of the outer ring and cover the entire outer ring from the radially outer side.

[0023] In this case, the support cylinder covers the entire outer ring, including the flange, from the radially outer side. Therefore, accidental deflection or other displacements of the flange can be effectively suppressed, as can displacement of the entire outer ring towards the radially outer side. Thus, the torque stiffness of the gear mechanism can be further improved.

[0024] (3) Alternatively, when viewed from the direction along the axis of the rolling element, the flange is formed to protrude from the rolling surface toward the axis in such a way that it covers more than 20% of the diameter of the rolling element, and contacts the end face of the rolling element by means of the flange surface.

[0025] In this case, the flange portion can be formed relatively long from the rolling surface of the outer ring toward the axis of the rolling element. In particular, since the flange portion is formed to be longer, covering more than 20% of the diameter of the rolling element when viewed along the axis, it is possible for the flange surface to contact the end face of the rolling element near the center of rotation (axis) of the rolling element. Therefore, the rotational resistance at the start of rolling is reduced, and the starting torque is reduced. Consequently, the initial drive of the main bearing is more stable, and the operational reliability of the main bearing is further improved.

[0026] (4) Alternatively, the flange surface may not contact the portion of the end face of the rolling element located on the outer peripheral side of the rolling element.

[0027] In this case, instead of the entire flange surface contacting the end face of the rolling element, the flange surface contacts the end face at a position close to the rotation center (axis) of the rolling element, without contacting the portion of the end face located on the outer periphery side of the rolling element. Therefore, the starting torque of the rolling element can be reduced more effectively. Consequently, the initial drive stability of the main bearing can be improved more effectively.

[0028] (5) Alternatively, the support cylinder may be in contact with the outer peripheral surface of the outer ring.

[0029] In this case, the support cylinder covers the outer ring from the radial outside while in contact with the outer circumferential surface of the outer ring. Therefore, it is possible to more effectively suppress accidental deflection and other displacements of the flange portion.

[0030] (6) Alternatively, the first length of the support cylinder along the radial direction may be longer than the second length along the radial direction between the outer circumferential surface of the outer ring and the intersection point.

[0031] In this case, the wall thickness of the support cylinder (the first length along the radial direction) can be made longer than the thickness of the root periphery of the thin-walled portion of the outer ring flange (the second length along the radial direction). Therefore, it is possible to properly prevent unexpected deflection or other displacements of the flange by using a support cylinder with sufficient rigidity.

[0032] (7) Alternatively, the outer diameter of the inner ring may be formed to be larger than the outer diameter of the gear carrier, such that when viewed from the direction along the central axis, a portion of the inner ring is exposed to a position further outward in the radial direction than the outer circumferential surface of the gear carrier.

[0033] In this case, a portion of the inner ring can be exposed radially outward from the outer circumferential surface of the gear carrier. Therefore, if a spacer is provided between the inner ring and the gear carrier, the spacer replacement operation can be performed more efficiently. For example, a jig or similar tool can be used to press down the portion of the inner ring exposed radially outward from the outer circumferential surface of the gear carrier. This allows for easy disassembly of the gear carrier and further efficient spacer replacement.

[0034] The effects of the invention

[0035] The gear mechanism according to the invention can maintain sufficient torque stiffness while restricting the movement of the rolling elements along the axis. Attached Figure Description

[0036] Figure 1 This is a side view (partial sectional view) showing an embodiment of the gear device of the present invention.

[0037] Figure 2 It is Figure 1 The enlarged sectional view of the periphery of the main bearing shown.

[0038] Figure 3 It means Figure 2 A three-dimensional view of the periphery of the rolling element (roller).

[0039] Figure 4 This is a diagram illustrating the method for determining moment stiffness based on axial load.

[0040] Figure 5 This is a diagram illustrating the method for determining moment stiffness based on radial load.

[0041] Figure 6 This is a diagram illustrating the torque stiffness of the gear mechanism.

[0042] Explanation of reference numerals in the attached figures

[0043] O, central axis; H1, wall thickness of the support cylinder (first length); H2, second length; R1, R2, roller axis (axis of rolling element); 1, gear assembly; 2, housing; 2g, 2h, support cylinder; 3, gear carrier; 4, reduction mechanism (gear mechanism); 5, first main bearing (main bearing); 6, second main bearing (main bearing); 51, 61, outer ring; 51a, 61a, outer ring track surface (rolling surface); 51b, 61b, flange; 52, 62, inner ring; 53, 63, roller (rolling element); 53a, 63a, end face of roller; 61b1, flange surface; 61e, outer circumferential surface of outer ring; 61p, intersection. Detailed Implementation

[0044] Hereinafter, embodiments of the gear device of the present invention will be described based on the accompanying drawings.

[0045] Figure 1 This is a side view (partial sectional view) of the gear device in this embodiment. Figure 2 It is Figure 1 An enlarged sectional view of the periphery of the main bearing (second main bearing) shown.

[0046] like Figure 1 As shown, the gear device 1 in this embodiment is, for example, an eccentric oscillating type gear transmission device.

[0047] The gear device 1 includes a housing 2, a gear carrier 3, a reduction mechanism (an example of the gear mechanism of the present invention) 4, a first main bearing (an example of the main bearing of the present invention) 5, a second main bearing (an example of the main bearing of the present invention) 6, and a sealing part 7.

[0048] The gear carrier 3 is rotatably assembled with the housing 2. The reduction mechanism 4 reduces the rotation of a drive source such as a motor (not shown) and transmits it to the housing 2 or the gear carrier 3. The first main bearing 5 and the second main bearing 6 support the gear carrier 3 so that it can rotate freely relative to the housing 2. The sealing part 7 seals the space between the housing 2 and the gear carrier 3.

[0049] The housing 2 is fixed to an outer shell (not shown). The outer shell may contain, for example, a drive source. The housing 2 is formed as a cylinder centered on the central axis O.

[0050] The inner circumferential surface 11 of the housing 2 is formed in a multi-stage shape along the central axis O in a manner that performs different functions. Specifically, the inner circumferential surface 11 of the housing 2 is formed in a multi-stage shape in a manner that functions as an internal gear 12, a first outer ring retaining part 13, a second outer ring retaining part 14, and a first sealing part 15.

[0051] Multiple pin grooves 12a are formed in the internal gear 12. The first outer ring retaining part 13 retains the outer ring 51 of the first main bearing 5. The second outer ring retaining part 14 retains the outer ring 61 of the second main bearing 6.

[0052] Furthermore, in this embodiment, the direction along the central axis O is defined as the axial direction. The rotational direction of the gear carrier 3 about the central axis O is defined as the circumferential direction. Moreover, the radial direction of the gear carrier 3 and the housing 2 is defined as the radial direction. Therefore, when viewed from the axial direction, the radial direction intersects the central axis O.

[0053] The portion of the housing 2 that opens toward the first module 20 constituting the gear carrier 3 is defined as the first opening end 11a. Furthermore, the portion of the housing 2 that opens toward the second module 21 constituting the gear carrier 3 is defined as the second opening end 11b.

[0054] The first outer ring retaining portion 13 and the second outer ring retaining portion 14 are arranged on both sides of the axial direction, clamping the internal gear 12 in the middle. Specifically, the first outer ring retaining portion 13 is arranged at a position closer to the first opening end 11a than the internal gear 12. The second outer ring retaining portion 14 is arranged at a position closer to the second opening end 11b than the internal gear 12.

[0055] Therefore, the internal gear 12 is axially positioned between the first outer ring retaining portion 13 and the second outer ring retaining portion 14.

[0056] Multiple pin grooves 12a extend axially. The multiple pin grooves 12a are formed at equal intervals in the circumferential direction. Each pin groove 12a holds an internal toothed pin 16.

[0057] The first outer ring retaining portion 13 is disposed axially adjacent to the internal gear 12 and is located at a position closer to the first opening end 11a than the internal gear 12. The first outer ring retaining portion 13 is disposed radially outward than the pin groove 12a.

[0058] The first outer ring retaining portion 13 includes a first stepped surface 13a and a first circumferential surface 13b. The first stepped surface 13a is formed as an annular shape extending radially outward from the end of the internal gear 12 located on the side of the first opening end 11a. The first circumferential surface 13b is formed as extending axially from the outer circumferential end of the first stepped surface 13a toward the first opening end 11a.

[0059] The first sealing portion 15 is disposed axially adjacent to the first outer ring retaining portion 13, and is positioned closer to the first opening end 11a than the first outer ring retaining portion 13. In the illustrated example, the inner diameter of the first sealing portion 15 is the same as the inner diameter of the first circumferential surface 13b. Therefore, the first sealing portion 15 is formed flush with the first circumferential surface 13b. The first sealing portion 15 serves to retain the sealing portion 7.

[0060] Furthermore, the first sealing portion 15 includes the first open end 11a of the housing 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 retain the sealing portion 7.

[0061] like Figure 1 and Figure 2 As shown, the second outer ring retaining portion 14 is arranged axially adjacent to the internal gear 12 and is positioned closer to the second opening end 11b than the internal gear 12. The second outer ring retaining portion 14 is arranged radially outward than the pin groove 12a.

[0062] In addition, the second outer ring retaining portion 14 may also include the second opening end 11b of the housing 2.

[0063] The second outer ring retaining portion 14 has a second stepped surface 14a and a second circumferential surface 14b. The second stepped surface 14a is formed into an annular shape extending radially outward from the end of the internal gear 12 located on the side of the second opening end 11b. The second circumferential surface 14b is formed to extend axially from the outer circumferential end of the second stepped surface 14a toward the second opening end 11b.

[0064] In this embodiment, the example will be described as follows: the radial length of the first step surface 13a is equal to the radial length of the second step surface 14a. Furthermore, the example will be described as follows: the inner diameter of the first circumferential surface 13b is the same as the inner diameter of the second circumferential surface 14b.

[0065] like Figure 1 As shown, the gear carrier 3 is connected to a driven part or a fixed part (not shown). The gear carrier 3 is disposed on the radially inner side of the housing 2. The gear carrier 3 rotates relative to the housing 2 about the central axis O as the first oscillating gear 43 and the second oscillating gear 44 (described later) oscillate and rotate.

[0066] The gear carrier 3 includes a first module 20 and a second module 21. The first module 20 and the second module 21 are arranged in an axial direction.

[0067] Furthermore, in the following description, the end of the gear carrier 3 located on the side of the first module 20 is defined as the first end 3a, and the end of the gear carrier 3 located on the side of the second module 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 gear carrier 3 as a whole.

[0068] The first end 3a and the second end 3b of the gear carrier 3 protrude outward in the axial direction from the housing 2. Specifically, the first end 3a of the gear carrier 3 protrudes outward in the axial direction from the first open end 11a of the housing 2. Moreover, the second end 3b of the gear carrier 3 protrudes outward in the axial direction from the second open end 11b of the housing 2.

[0069] The first module 20 includes: a base 22, which is supported on the housing 2 by means of a first main bearing 5; and a plurality of support portions 23 and flange portions 24, which are integrally formed with the base 22.

[0070] The base 22 is shaped, for example, as a circular plate centered on the central axis O. Multiple support sections 23 are formed to protrude axially from the end face of the base 22 toward the second end 3b. The multiple support sections 23 are arranged at equal intervals with open spaces in the circumferential direction.

[0071] Multiple support sections 23 are inserted with gaps into multiple through holes 47 formed in the first oscillating gear 43 and the second oscillating gear 44, which will be described later. Thus, the multiple support sections 23 connect the base 22 to the second module 21 while maintaining a non-contact state with respect to the first oscillating gear 43 and the second oscillating gear 44.

[0072] A flange portion 24 is provided at the end of the base portion 22 located on the first end 3a side. The flange portion 24 is, for example, formed into a circular plate shape centered on the central axis O. Furthermore, the flange portion 24 is formed to protrude radially outward from the base portion 22. Thus, the flange portion 24 is arranged to overlap with the end face of the housing 2 when viewed from the axial direction. In addition, the flange portion 24 functions as a mounting surface for mounting to a driven part or a fixed part (not shown).

[0073] The outer peripheral surface 25 of the base 22 is formed in a multi-level shape along the central axis O to perform different functions. Specifically, the outer peripheral surface 25 of the base 22 is formed in a multi-level shape to function as a first inner ring retaining part 26 and a second sealing part 27 located at a position closer to the first end 3a than the first inner ring retaining part 26.

[0074] The first inner ring retaining portion 26 retains the inner ring 52 of the first main bearing 5. The sealing portion 7 is disposed at a position closer to the first end 3a than the first inner ring retaining portion 26.

[0075] The first inner ring retaining portion 26 includes a first circumferential surface 26a and a first stepped surface 26b.

[0076] The first circumferential surface 26a is formed as an annular shape extending axially from the end of the base 22 located on the side of the second end 3b toward the side of the first end 3a. The first step surface 26b is formed as an annular shape extending radially outward from the first circumferential surface 26a.

[0077] At least a portion of the first circumferential surface 26a is radially opposed to the first circumferential surface 13b of the first outer ring retaining portion 13.

[0078] The second sealing portion 27 is disposed adjacent to the first inner ring retaining portion 26 along the axial direction. The outer diameter of the second sealing portion 27 is larger than the outer diameter of the first circumferential surface 26a of the first inner ring retaining portion 26. The second sealing portion 27 faces the first sealing portion 15 in the radial direction. Thus, the second sealing portion 27 can cooperate with the first sealing portion 15 to retain the sealing portion 7.

[0079] like Figure 1 and Figure 2 As shown, the second module 21 is supported on the housing 2 by means of the second main bearing 6. The second module 21 is shaped, for example, into a circular plate with the central axis O as the center. The second module 21 is fixed to the front end of a plurality of support sections 23 by means of fastening members 21b.

[0080] The outer peripheral surface 28 of the second module 21 is formed in a multi-level shape along the central axis O. Specifically, the outer peripheral surface 28 of the second module 21 is formed in a multi-level shape in a manner that functions as a second inner ring retaining part 29.

[0081] The second inner ring retaining portion 29 is formed in the portion located on the first end 3a side of the outer peripheral surface 28 of the second module 21. The second inner ring retaining portion 29 retains the inner ring 62 of the second main bearing 6.

[0082] The second inner ring retaining portion 29 includes a second circumferential surface 29a and a second stepped surface 29b.

[0083] The second peripheral surface 29a is formed as an annular shape extending from the end of the second module 21 located on the side of the first end 3a toward the side of the second end 3b. The second stepped surface 29b is formed as an annular shape extending from the second peripheral surface 29a toward the radially outward side. At least a portion of the second peripheral surface 29a faces the second peripheral surface 14b of the second outer ring retaining portion 14 in the radial direction.

[0084] In this embodiment, the example will be described as follows: the outer diameter of the first circumferential surface 26a is the same as the outer diameter of the second circumferential surface 29a. Furthermore, the example will be described as follows: the radial length of the first step surface 26b is equal to the radial length of the second step surface 29b.

[0085] (Speed ​​reduction mechanism)

[0086] like Figure 1 As shown, the reduction mechanism 4 includes a drive shaft 70, multiple transmission gears 41, multiple crankshafts 42, a first oscillating gear 43, and a second oscillating gear 44.

[0087] The drive shaft 70 is, for example, coaxially arranged 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. Multiple crankshafts 42 are respectively connected to the multiple transmission gears 41.

[0088] Multiple transmission gears 41 and multiple crankshafts 42 are arranged coaxially with an eccentric axis P. The eccentric axis P is arranged circumferentially at equal intervals 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 circumferentially at equal intervals with respect to each other.

[0089] Each crankshaft 42 has a shaft portion 42a and two eccentric portions 42b.

[0090] The shaft portion 42a is supported on the gear carrier 3. Two eccentric portions 42b are provided on the shaft portion 42a and are eccentric relative to the eccentric axis P. The two eccentric portions 42b are circular in shape and are eccentric in different directions relative to the eccentric axis P.

[0091] Each crankshaft 42 is inserted into a through hole (not shown) formed in the gear carrier 3 (module 1 20 and module 21). At this time, the shaft portion 42a of each crankshaft 42 is inserted into the through hole by means of bearings 45. The bearings 45 are respectively positioned near both ends of the shaft portion 42a. A pair of bearings 45 support the shaft portion 42a within the through hole.

[0092] In each crankshaft 42, one of the two eccentric portions 42b is inserted into a through hole (not shown) formed in the first oscillating gear 43 by means of a bearing 46. The other eccentric portion 42b is inserted into a through hole (not shown) formed in the second oscillating gear 44 by means of a bearing 46.

[0093] Therefore, the first oscillating gear 43 and the second oscillating gear 44 oscillate and rotate in conjunction with the relative rotation of the two eccentric portions 42b of each crankshaft 42. As a result, the housing 2 and the gear carrier 3 can rotate relative to each other.

[0094] The first oscillating gear 43 and the second oscillating gear 44 are each formed, for example, into a circular plate shape with an outer diameter smaller than the inner diameter of the internal gear 12 of the housing 2. The first oscillating gear 43 and the second oscillating gear 44 are each formed with the same number of through holes 47 as the plurality of support portions 23.

[0095] Each support portion 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 portion 23, so as not to hinder the swing rotation of the first swing gear 43 and the second swing gear 44.

[0096] The outer peripheral surfaces of the first oscillating gear 43 and the second oscillating gear 44 are each formed with external teeth 48 that mesh with a plurality of internal toothed pins 16. The number of external teeth 48 is different from the number of internal toothed pins 16.

[0097] The first oscillating gear 43 and the second oscillating gear 44 move eccentrically together with the eccentric portion 42b as each crankshaft 42, which receives the rotational driving force from the drive shaft 70, rotates. As a result, the first oscillating gear 43 and the second oscillating gear 44 oscillate and rotate in a state in which the external teeth 48 are engaged with the plurality of internal tooth pins 16.

[0098] In this embodiment, when the housing 2 is fixed to a fixed member (not shown), the first oscillating gear 43 and the second oscillating gear 44 rotate together with the gear carrier 3 about the central axis O relative to the housing 2.

[0099] In contrast, when the gear 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 housing 2 about the central axis O relative to the gear carrier 3.

[0100] The sealing portion 7 is formed in an annular shape, for example, and is arranged radially between the first sealing portion 15 and the second sealing portion 27. The sealing portion 7 seals the annular space formed between the housing 2 and the gear carrier 3. The sealing portion 7, for example, prevents foreign matter from entering into the annular space from the outside, and prevents liquid lubricants or the like accumulated in the annular space from flowing out to the outside.

[0101] (Main bearing)

[0102] like Figure 1 As shown, the first main bearing 5 and the second main bearing 6 are tapered roller bearings.

[0103] The first main bearing 5 is disposed between the housing 2 and the base 22 of the first module 20 of the gear carrier 3. The first main bearing 5 includes an outer ring 51, an inner ring 52, a plurality of rollers (an example of the rolling elements of the present invention) 53 and a cage (retainer) 54.

[0104] The inner ring 52 is disposed radially inside the outer ring 51. A plurality of rollers 53 are disposed between the outer ring 51 and the inner ring 52 in a rolling manner. A cage 54 is disposed between the outer ring 51 and the inner ring 52.

[0105] The outer ring 51 is formed into a ring shape centered on the central axis O. The outer ring 51 contacts the first stepped surface 13a of the first outer ring retaining part 13 from the outer side of the axial direction (the side of the first opening end 11a) and fits into the first circumferential surface 13b of the first outer ring retaining part 13.

[0106] The outer ring 51 has an outer ring track surface (an example of the rolling surface of the present invention) 51a on its inner circumferential surface.

[0107] The outer ring track surface 51a is inclined relative to the central axis O. The outer ring track surface 51a is inclined in a way that it moves radially outward as it moves outward in the axial direction (towards the first opening end 11a). The outer ring track surface 51a is formed as a conical surface that is inclined in a way that it moves away from the central axis O as it moves axially from the first step surface 13a toward the first opening end 11a.

[0108] Therefore, the inner diameter of the outer ring track surface 51a is smaller as it gets closer to the first step surface 13a, and larger as it gets closer to the first opening end 11a.

[0109] The outer ring 51 has a flange portion 51b.

[0110] The flange portion 51b is positioned radially outward from each roller 63 and is formed to protrude from the outer raceway surface 51a toward the roller axis (an example of the axis of 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. Thus, the flange portion 51b holds the position of each roller 53 at a predetermined position on the outer raceway surface 51a.

[0111] The inner ring 52 is formed into a circular shape coaxial with the outer ring 51. The inner ring 52 is held by the first inner ring retaining portion 26 of the base 22. Specifically, the inner ring 52 contacts the first stepped surface 26b from the inner side (second end 3b side) in the axial direction and fits into the first circumferential surface 26a.

[0112] The inner ring 52 has an inner ring track surface (rolling surface) 52a on its outer circumferential surface.

[0113] The inner ring track surface 52a is inclined so as to face the outer ring track surface 51a of the outer ring 51 across the roller axis R1. The inner ring track surface 52a is formed as a conical surface that is inclined axially away from the central axis O as it moves from the second end 3b toward the first step surface 26b.

[0114] Therefore, the inner diameter of the inner track surface 52a is smaller as it gets closer to the second end 3b, and larger as it gets closer to the first step surface 26b.

[0115] Each roller 53 is a conical roller with a frustum-shaped profile. Each roller 53 is arranged in a rolling manner between the outer raceway surface 51a of the outer ring 51 and the inner raceway surface 52a of the inner ring 52. Viewed axially, each roller 53 is arranged radially with the central axis O as the center, at equal intervals in the circumferential direction. Each roller 53 is arranged such that its end face 53a on the larger diameter side of both ends of the roller axis R1 faces the first open end 11a.

[0116] Each roller 53 rolls on the outer ring track surface 51a of the outer ring 51 and the inner ring track surface 52a of the inner ring 52, while rotating circumferentially around the central axis O.

[0117] The retainer 54 holds multiple rollers 53.

[0118] The retainer 54 includes: a first annular portion and a second annular portion extending circumferentially; and a plurality of connecting portions connecting the first annular portion and the second annular portion.

[0119] The first annular portion and the second annular portion are configured to correspond to the first annular portion 65 and the second annular portion 66 in the second main bearing 6, which will be described later. Furthermore, the connecting portion is configured to correspond to the connecting portion 67 in the second main bearing 6, which will also be described later. Therefore, detailed descriptions of the first annular portion, the second annular portion, and the connecting portion are omitted regarding the retainer 54 of the first main bearing 5.

[0120] like Figure 1 and Figure 2 As shown, the second main bearing 6 is disposed between the housing 2 and the second module 21 of the gear carrier 3. The second main bearing 6 includes an outer ring 61, an inner ring 62, a plurality of rollers (an example of the rolling elements of the present invention) 63, and a cage (retainer) 64.

[0121] The inner ring 62 is disposed radially inside the outer ring 61. A plurality of rollers 63 are disposed between the outer ring 61 and the inner ring 62 in a rolling manner. A cage 64 is disposed between the outer ring 61 and the inner ring 62.

[0122] The outer ring 61 is formed in a circular shape centered on the central axis O. With its end face 61d contacting the second stepped surface 14a of the second outer ring retaining portion 14 from the outer side of the axial direction (the side of the second opening end 11b), the outer peripheral surface 61e of the outer ring 61 is fitted into the second peripheral surface 14b of the second outer ring retaining portion 14. Therefore, the outer peripheral surface 61e of the outer ring 61 is in contact with the second peripheral surface 14b.

[0123] The outer ring 61 has an outer ring track surface (an example of the rolling surface of the present invention) 61a, which serves as the inner circumferential surface.

[0124] The outer ring track surface 61a is inclined relative to the central axis O. The outer ring track surface 61a is inclined in a way that it moves radially outward as it moves axially outward (towards the second opening end 11b). The outer ring track surface 61a is formed as a conical surface that is inclined axially away from the central axis O as it moves away from the second step surface 14a toward the second opening end 11b.

[0125] Therefore, the inner diameter of the outer ring track surface 61a is smaller as it gets closer to the second step surface 14a, and larger as it gets closer to the second opening end 11b.

[0126] The outer ring 61 has a flange portion 61b.

[0127] A flange 61b is positioned radially outward from each roller 63 and is formed to protrude from the outer raceway surface 61a toward the roller axis (an example of the axis of the present invention) R2. The flange 61b supports each roller 63 by contacting the end face 63a of each roller 63. More specifically, the flange 61b restricts the movement of each roller 63 in the direction along the roller axis R2, thereby maintaining the position of each roller 63 at a predetermined position on the outer raceway surface 61a.

[0128] The inner ring 62 is formed into a circular shape coaxial with the outer ring 61. The inner ring 62 is held in the second inner ring holding portion 29. Specifically, the inner ring 62 contacts the second stepped surface 29b from the inner side (first end 3a side) in the axial direction through the spacer 69, and fits into the second circumferential surface 29a.

[0129] The spacer 69 is formed in an annular shape centered on 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 module 21.

[0130] In the illustrated example, the case where the inner diameter of spacer 69 is slightly larger than the outer diameter of the second circumferential surface 29a, and the outer diameter of spacer 69 is slightly smaller than the outer diameter of the outer circumferential surface 28 of the second module 21, is taken as an example.

[0131] The spacer 69 is configured to be axially sandwiched between the inner ring 62 and the second module 21. The spacer 69 serves to apply preload to the first main bearing 5 and the second main bearing 6.

[0132] Therefore, by adjusting the thickness of the spacer 69 through operations such as replacing the spacer 69, the preload of the first main bearing 5 and the second main bearing 6 can be adjusted.

[0133] The inner ring 62 has an inner ring track surface (rolling surface) 62a on its outer circumferential surface.

[0134] The inner ring track surface 62a is inclined so as to face the outer ring track surface 61a of the outer ring 61 across the roller axis R2. The inner ring track surface 62a is formed as a conical surface that is inclined axially away from the central axis O as it moves from the first end 3a toward the second step surface 29b.

[0135] Therefore, the inner diameter of the inner track surface 62a is smaller the closer it is to the first end 3a, and larger the closer it is to the second step surface 29b.

[0136] Each roller 63 is a tapered roller with a frustum-shaped profile. The roller axis R2 of each roller 63 is inclined at a predetermined angle relative to the axial direction in the opposite direction to that of each roller 53 of the first main bearing 5. Each roller 63 is disposed between the outer ring raceway surface 61a of the outer ring 61 and the inner ring raceway surface 62a of the inner ring 62.

[0137] like Figure 2 and Figure 3 As shown, when viewed from the axial direction, each roller 63 is arranged at equal intervals in the circumferential direction in a radial arrangement with the central axis O as the center. Figure 3 It is Figure 2An enlarged perspective view of the vicinity of the end face 63a of the roller 63 of the second main bearing 6. Furthermore, in Figure 3 The illustration of retainer 64 is omitted.

[0138] Each roller 63 is arranged such that the end face 63a of the larger diameter portion at both ends along the roller axis R2 faces the second open end 11b. Each roller 63 rotates circumferentially about the central axis O while rolling on the outer ring track surface 61a of the outer ring 61 and the inner ring track surface 62a of the inner ring 62.

[0139] The retainer 64 holds multiple rollers 63.

[0140] The retainer 64 includes: a first annular portion 65 and a second annular portion 66 extending circumferentially; and a plurality of connecting portions 67 connecting the first annular portion 65 and the second annular portion 66.

[0141] The first annular portion 65 extends circumferentially along the end face of one of the plurality of rollers 63 opposite to the end face 63a. The second annular portion 66 is disposed on the side opposite to the first annular portion 65, separated by the plurality of rollers 63, and extends circumferentially along the end face 63a of the plurality of rollers 63.

[0142] 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 track surface 61a of the outer ring 61 and the inner ring track surface 62a of the inner ring 62, and connects the first annular portion 65 and the second annular portion 66 along the roller axis R2.

[0143] Furthermore, each connecting part 67 is separately configured from the outer ring track surface 61a and the inner ring track surface 62a.

[0144] The retainer 64 has a recess formed by a first annular portion 65, a second annular portion 66, and a pair of circumferentially adjacent connecting portions 67. Therefore, the recesses are arranged at circumferential intervals. Each roller 63 is held within its respective recess in a rolling manner.

[0145] The first main bearing 5 and the second main bearing 6 are further described in detail.

[0146] The first main bearing 5 and the second main bearing 6 are arranged substantially symmetrically in the axial direction and have substantially the same structure. Therefore, in this embodiment, the second main bearing 6 will be described in detail.

[0147] like Figure 1 and Figure 2As shown, the flange portion 61b of the outer ring 61 contacts the end face 63a of each roller 63, thereby restricting the movement of each roller 63 along the roller axis R2. The flange portion 61b has a flange surface 61b1 that contacts the end face 63a of each roller 63.

[0148] In this embodiment, the intersection point (imaginary intersection point) where the outer ring track surface 61a of the outer ring 61 intersects with the flange surface 61b1 of the flange portion 61b is defined as intersection point 61p. Intersection point 61p is located at the root portion 61f of the flange portion 61b, which is a thin-walled portion.

[0149] Moreover, such as Figure 2 and Figure 3 As shown, the flange portion 61b is formed such that, when viewed along the roller axis R2, it protrudes from the outer raceway surface 61a toward the roller axis R2 in such a way that it covers more than 20% of the maximum diameter of each roller 63. Thus, the flange portion 61b contacts the end face 63a of the roller 63 via the flange surface 61b1. Consequently, the flange portion 61b is formed such that, when viewed along the roller axis R2, the distance along the end face 63a between the roller axis R2 and the flange portion 61b is less than 30% of the maximum diameter of the roller 63.

[0150] like Figure 2 As shown, the flange portion 61b is formed such that the entire flange surface 61b1 does not contact the end face 63a, but rather the portion of the end face 63a located near the roller axis R2. Therefore, the flange portion 61b is formed such that the flange surface 61b1 does not contact the portion of the end face 63a located on the outer peripheral side of the roller 63.

[0151] Specifically, a clearance portion 68 is formed at the root 61f of the flange portion 61b to avoid contact with the portion of the end face 63a located on the outer peripheral side of the roller 63. The clearance portion 68 is formed to be a semi-circular recess facing outward in longitudinal section. As a result, the flange surface 61b1 can contact the portion of the end face 63a located near the roller axis R2.

[0152] (Support cylinder)

[0153] like Figure 2 As shown, the housing 2 has a support cylinder 2g that covers the outer ring 61 of the second main bearing 6 from the radially outer side.

[0154] The support cylinder 2g is formed to extend axially toward the outside (towards the second end 3b of the gear carrier 3) away from the first oscillating gear 43 and the second oscillating gear 44, and is formed to be cylindrical with an inner circumferential surface and an outer circumferential surface 2g1.

[0155] In particular, the inner circumferential surface of the support cylinder 2g functions as the second circumferential surface 14b of the second outer ring retaining portion 14. Therefore, the support cylinder 2g having the second circumferential surface 14b constitutes a part of the second outer ring retaining portion 14.

[0156] The support cylinder 2g is formed to cover the outer ring 61 radially outward and at least radially cover the intersection point 61p. In the illustrated example, the support cylinder 2g extends axially outward beyond the outer end face 61c of the outer ring 61. Therefore, the support cylinder 2g covers the entire outer ring 61 radially outward. Moreover, the support cylinder 2g contacts the outer peripheral surface 61e of the outer ring 61 without gaps along its entire length.

[0157] Thus, the outer ring 61 is held radially outward by the support cylinder 2g (second outer ring retaining part 14).

[0158] In particular, the support cylinder 2g covers the intersection point 61p of the root portion 61f of the flange portion 61b, which is a thin-walled portion, from the radially outer side. Therefore, the support cylinder 2g can suppress unexpected displacement (retraction) such as deflection of the flange portion 61b towards the radially outer side. As a result, the support cylinder 2g can function as a support member that strengthens the rigidity of the flange portion 61b.

[0159] Furthermore, the support cylinder 2g extends axially with a constant wall thickness H1 (the first length of the present invention). Therefore, the wall thickness H1 of the support cylinder 2g is constant throughout its entire length. In addition, the wall thickness H1 of the support cylinder 2g corresponds to the radial interval between the second circumferential surface 14b, which is the inner circumferential surface, and the outer circumferential surface 2g1.

[0160] In particular, the wall thickness H1 of the support cylinder 2g is formed to be longer (larger) than the radial distance H2 (the second length of the invention) between the outer peripheral surface 61e of the outer ring 61 and the intersection point 61p.

[0161] Corresponding to the support cylinder 2g constructed as described above, such as Figure 1 As shown, the portion of housing 2 that surrounds the first main bearing 5 and the sealing portion 7 from the radially outer side functions as a support cylinder 2h. Therefore, the support cylinder 2h covers the entire outer ring 51 of the first main bearing 5, including the flange portion 51b, from the radially outer side and constitutes a portion of the first outer ring retaining portion 13. The support cylinder 2h and the first main bearing 5 have the same relationship as the relationship between the support cylinder 2g and the second main bearing 6.

[0162] (The function of the gear mechanism)

[0163] Next, the operation of the gear assembly 1 configured as described above will be explained. In particular, the explanation will focus on the second main bearing 6.

[0164] In the gear assembly 1 of this embodiment, the flange surface 61b1 of the flange portion 61b formed on the outer ring 61 contacts the end face 63a of each roller 63. Therefore, the flange portion 61b can restrict accidental movement of each roller 63 in the direction along the roller axis R2. This allows the multiple rollers 63 to roll stably around the roller axis R2 between the inner ring 62 and the outer ring 61, maintaining the operational reliability of the second main bearing 6. Consequently, the housing 2 and the gear carrier 3 can rotate stably relative to each other around the central axis O.

[0165] In particular, the housing 2 has a support cylinder 2g that surrounds the outer ring 61 radially outward throughout its entire circumference. Furthermore, the support cylinder 2g covers at least radially outward the imaginary intersection point 61p where the outer ring rolling surface 61a intersects with the flange surface 61b1 of the flange portion 61b. Therefore, the support cylinder 2g can radially outward cover the root portion (thin-walled portion) 61f of the flange portion 61b located near the intersection point 61p. Thus, the support cylinder 2g can suppress unexpected displacement (retraction) of the flange portion 61b, such as radial outward deflection.

[0166] Therefore, during the operation of the gear assembly 1, even if the flange portion 61b is to displace radially outward with the root portion 61f as the base point due to, for example, a torque load acting on the second main bearing 6, the displacement of the flange portion 61b can be suppressed by the support sleeve 2g, which functions as a support member. As a result, the gear assembly 1 can be made to ensure sufficient torque stiffness.

[0167] Specifically, it can increase the torque stiffness [Nm / arc.min.] of gear device 1 by about 5% to 20%.

[0168] In summary, the gear device 1 according to this embodiment can maintain sufficient torque stiffness while restricting the movement of the plurality of rollers 63 along the roller axis R2.

[0169] In addition, the torque stiffness of the gear device 1 refers to the torque load value required to tilt the gear carrier 3 relative to the housing 2 by a unit angle. The larger the value, the higher the stiffness.

[0170] Specifically, the torque stiffness of the gear device 1 refers to the quantity defined by "△M / △θ" relative to the torque △M required to return the axis of the gear carrier 3 to the direction of the central axis O of the housing 2 when the axis of the gear carrier 3 is tilted by an angle △θ relative to the central axis O of the housing 2.

[0171] To support the gear carrier 3 against unbalanced centrifugal forces and inertial forces such as vibrations acting on it from the outside, the first main bearing 5 and the second main bearing 6 need to consider not only the balance of radial forces but also the balance of torques. In this case, the bearing stiffness of the first main bearing 5 and the second main bearing 6 is responsible for the balance of torques and forces.

[0172] Moment stiffness, for example, utilizes Figure 4 The axial load method shown or Figure 5 The radial load method shown is used for measurement. Furthermore, Figure 4 This is a diagram illustrating the method for determining moment stiffness based on axial load. Figure 5 This is a diagram illustrating the method for determining moment stiffness based on radial load.

[0173] In the case of measuring moment stiffness, such as Figure 4 and Figure 5 As shown, for example, with the housing 2 of the gear assembly 1 fixed to the fixing part S1, the rod-shaped measuring part S2 is mounted on the gear carrier 3. Next, an axial load F is applied to the front end of the measuring part S2, and the displacement of the outer periphery of the housing 2 is measured using a displacement gauge S4 (see reference). Figure 4 In addition, in Figure 4 In the diagram, the displacement gauge S4 is indicated by an arrow. Alternatively, a radial load F is applied to the front end of the measuring unit S2, and the displacement gauge S4 is used to measure the displacement near the outer periphery of the gear carrier 3 (see reference). Figure 5 ).

[0174] In this case, the torque ΔM 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 the housing 2 or gear carrier 3). Additionally, the angle Δθ can be calculated based on the measured value of the displacement gauge S4 and the distance I (the distance between the displacement gauge S4 and the center point of the housing 2 or gear carrier 3).

[0175] The torque stiffness of gear device 1 can be determined using the above methods.

[0176] Furthermore, in the gear device 1 of this embodiment, such as Figure 2 As shown, the support cylinder 2g covers the entire outer ring 61, including the flange portion 61b, from the radially outer side. Therefore, it can effectively suppress accidental deflection and other displacements of the flange portion 61b, and can also suppress the displacement of the entire outer ring 61 towards the radially outer side. Thus, the torque stiffness of the gear device 1 can be further improved.

[0177] In addition, the support cylinder 2g covers the outer ring 61 radially from the outside in a state of contact with the outer peripheral surface 61e of the outer ring 61, thus enabling it to exert the aforementioned effects more effectively.

[0178] Furthermore, the wall thickness H1 of the support cylinder 2g is larger than the radial distance H2 between the outer peripheral surface 61e of the outer ring 61 and the intersection point 61p, thus ensuring sufficient rigidity of the support cylinder 2g. Therefore, the support cylinder 2g can be used to prevent accidental deflection or other displacements of the flange portion 61b. Consequently, displacement of the flange portion 61b and displacement of the outer ring 61 as a whole can be effectively suppressed.

[0179] Furthermore, in this embodiment, considering the contact resistance between the flange 61b and the roller 63, there is a tendency for the contact resistance to increase as the contact area between the flange surface 61b1 and 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 61b and the end face 63a.

[0180] Furthermore, when considering the torque resistance acting on roller 63, the smaller the distance between the roller axis R2 and the flange 61b at end face 63a, the smaller the torque resistance from the flange 61b that hinders the rotation of roller 63. Moreover, the magnitude of the torque resistance is determined by the distance between the roller axis R2 and the flange 61b. Therefore, when the torque resistance to roller 63 is small, the rotational performance of roller 63 is improved, similar to suppressing the contact resistance to roller 63.

[0181] Furthermore, when the end face 63a is not a plane but a convex curved surface, the contact area between the flange surface 61b1 and the end face 63a can be reduced. Therefore, the contact resistance between the roller 63 and the flange portion 61b can be reduced, and the rotational resistance of the roller 63 can be reduced, thereby improving the rotational performance of the roller 63.

[0182] By combining the above-mentioned necessary conditions, the rotational resistance of roller 63 can be reduced, thereby improving its rotational performance.

[0183] In this respect, in this embodiment, when viewed from the direction along the roller axis R2, the flange portion 61b is formed to be relatively long, covering more than 20% of the maximum diameter of the roller 63. Therefore, the flange surface 61b1 can contact the end face 63a of the roller 63 near the roller axis R2. Furthermore, thanks to the clearance portion 68, the flange portion 61b does not contact the portion of the end face 63a located on the outer peripheral side.

[0184] Therefore, the rotational resistance when the roller 63 starts rolling can be reduced, and the starting torque can be reduced. Thus, 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. Consequently, the starting torque and drive torque of the gear assembly 1 can be stabilized.

[0185] Furthermore, unlike conventional main bearings where a flange portion 61b is formed on the inner ring 62, in this embodiment, a flange portion 61b is formed on the outer ring 61. Therefore, the spacer 69 can be replaced while suppressing external forces acting on the flange portion 61b.

[0186] For example, when replacing the spacer 69, even when the housing 2 and the second main bearing 6 are temporarily assembled together by pressing the inner ring 62 with a jig, external forces are unlikely to act on the flange portion 61b formed on the outer ring 61. Therefore, the spacer 69 can be replaced without paying excessive attention to the flange portion 61b. Thus, the preload adjustment of the second main bearing 6 using the spacer 69 can be performed efficiently.

[0187] In particular, the outer diameter of the inner ring 62 of the second main bearing 6 is larger than the outer diameter of the second module 21 constituting the gear carrier 3. Therefore, the outer circumferential surface 62c of the inner ring 62 protrudes radially outward than the outer circumferential surface 28 of the second module 21. Thus, when viewed axially, a portion of the inner ring 62 is exposed radially outward than the outer circumferential surface 28 of the second module 21, making this portion visually identifiable.

[0188] Therefore, before disassembling the second module 21, the portion of the inner ring 62 exposed radially outward from the outer peripheral surface 28 of the second module 21 can be pressed using a jig or similar device. This maintains the housing 2 and the second main bearing 6 in a temporarily assembled state. Consequently, accidental disassembly of the second main bearing 6 during removal of the second module 21 can be prevented.

[0189] Therefore, the spacer 69 can be easily replaced, and the preload of the second main bearing 6 can be easily and smoothly adjusted.

[0190] (Confirmation test)

[0191] Next, the verification test of torque stiffness, which is a specific example of the gear device in this invention, will be described.

[0192] In this confirmation test, for Figures 1-3 The torque stiffness of the gear device 1 shown in this embodiment was measured. As a measurement method, a... Figure 4 and Figure 5 The method shown was used to determine the moment stiffness. In this validation test, seven gear units 1 with altered outer diameters (outer diameters of housing 2) were prepared, and the moment stiffness was measured for each gear unit 1. The seven gear units 1 differed only in their outer diameters; otherwise, their structures were identical.

[0193] Figure 6This represents the results of measuring the torque stiffness of seven gear units 1 with different outer diameters.

[0194] exist Figure 6 In the diagram, "〇" indicates the torque stiffness measured for each of the seven gear units 1. For example... Figure 6 As shown, it can be understood that the larger the outer diameter of gear device 1 (outer diameter of housing 2), the greater the torque stiffness of gear device 1.

[0195] Furthermore, in this verification test, as a comparative example of the present invention, seven gear assemblies were prepared in which the flange portion 61b was not formed on the outer ring of the main bearing (e.g., the outer ring 61 of the second main bearing 6) but on the inner ring (e.g., the inner ring 62 of the second main bearing 6) as in the conventional manner. The torque stiffness of these seven gear assemblies was also measured.

[0196] exist Figure 6 In the figure, “◇” is used to indicate the torque stiffness measured for the seven gear devices used as comparative examples.

[0197] like Figure 6 As shown, it was actually confirmed that, compared with the gear device 1 of this embodiment, which is an example, the seven gear devices used as comparative examples all had lower torque stiffness for the same outer diameter. Specifically, compared with the conventional gear devices used as comparative examples, the torque stiffness of the gear device 1 of this embodiment increased by at least 105% and by a maximum of 117%.

[0198] Therefore, in the case where a flange portion 61b is formed on the outer ring 61 as in this embodiment, and the outer ring 61 is surrounded from the radial outside by the support cylinder 2g of the housing 2 and at least from the radial outside by the intersection point 61p of the flange surface 61b1 and the outer ring track surface 61a, it has been confirmed that the torque stiffness of the gear device 1 is increased by at least 5%.

[0199] Therefore, it has been confirmed that the unexpected displacement of the flange 61b can be suppressed by using the support cylinder 2g of the housing 2, thereby improving the moment stiffness.

[0200] The embodiments of the present invention have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Embodiments and their variations include, for example, techniques readily conceived by those skilled in the art, substantially the same techniques, techniques of equivalent scope, etc.

[0201] For example, in the above embodiment, the case where the reduction mechanism 4 uses a crankshaft 42 rotating about the eccentric axis P to make the first oscillating gear 43 and the second oscillating gear 44 oscillate and rotate is described. However, it is not limited to this structure.

[0202] For example, the reduction mechanism 4 may also have an input shaft 80 that is coaxial with the central axis O and has multiple eccentric portions 42b (see reference). Figure 1 The double-dotted line shown is used to replace the drive shaft 70, drive gear 70a, transmission gear 41, and multiple crankshafts 42. In this case, multiple oscillating gears that oscillate and rotate in conjunction with the rotation of multiple eccentric portions 42b can be used instead of the first oscillating gear 43 and the second oscillating gear 44. Even with this configuration, the same effect as the above-described embodiment can be achieved.

[0203] Furthermore, in the above embodiment, the example described is that the support cylinder 2g constituting the second outer ring retaining portion 14 covers the entire outer ring 61 of the second main bearing 6 from the radially outer side, but it is not limited to this case. For example, the support cylinder 2g can be formed to at least cover the intersection point 61p from the radially outer side.

[0204] Furthermore, the second circumferential surface 14b, which is the inner circumferential surface of the support cylinder 2g, does not necessarily need to contact the outer circumferential surface 61e of the outer ring 61. As long as the support cylinder 2g covers the outer ring 61 from the radial outside, a slight gap can be formed between the second circumferential surface 14b and the outer circumferential surface 61e of the outer ring 61.

[0205] Furthermore, in the above embodiment, the structure having spacer 69 was described as an example, but spacer 69 is not necessary and may not be included.

[0206] Furthermore, in the embodiments disclosed in this specification, for a component composed of multiple objects, these multiple objects can also be integrated into one, or conversely, a component composed of a single object can be divided into multiple objects. Whether or not they are integrated, as long as the configuration achieves the purpose of the invention, it is acceptable.

[0207] Furthermore, the present invention includes the following technical solutions.

[0208] <1>

[0209] A gear mechanism, characterized in that,

[0210] The gear mechanism has the following features:

[0211] The housing is configured to rotate about a central axis;

[0212] A gear carrier is arranged radially inside the housing in a manner that allows it to rotate relative to the central axis;

[0213] A gear mechanism that reduces rotational speed from the outside and transmits it to the housing or the gear carrier; and

[0214] The main bearing is disposed between the housing and the gear carrier.

[0215] The main bearing comprises:

[0216] The inner ring is located on the gear carrier;

[0217] Outer ring, which is disposed on the housing; and

[0218] Multiple rolling elements, held in a rolling manner between the inner and outer rings, rotate about an axis inclined relative to the central axis.

[0219] The outer ring has a flange portion that restricts the movement of the plurality of rolling elements in the direction along the axis.

[0220] The flange is positioned radially outward from the plurality of rolling elements and is formed to protrude from the rolling surface of the outer ring toward the axis.

[0221] Furthermore, the flange portion has a flange surface that contacts the end faces of the plurality of rolling elements.

[0222] The housing includes a support cylinder that extends along the central axis and covers the outer ring from the radially outer side.

[0223] The support cylinder covers at least the intersection of the rolling surface and the flange surface from the radially outer side.

[0224] <2>

[0225] According to the gear device described in <1>, wherein...

[0226] The support cylinder extends at least along the central axis to the outer end face of the outer ring and covers the entire outer ring from the radially outer side.

[0227] <3>

[0228] According to the gear device described in <1> or <2>, wherein,

[0229] When viewed from the direction along the axis of the rolling element, the flange is formed to protrude from the rolling surface toward the axis in such a way that it covers more than 20% of the diameter of the rolling element, and contacts the end face of the rolling element by means of the flange surface.

[0230] <4>

[0231] According to the gear device described in <3>, wherein...

[0232] The flange surface does not contact the portion of the end face of the rolling element located on the outer peripheral side of the rolling element.

[0233] <5>

[0234] The gear device according to any one of <1> to <4>, wherein,

[0235] The support cylinder is in contact with the outer peripheral surface of the outer ring.

[0236] <6>

[0237] According to the gear device described in <5>, wherein...

[0238] The first radial length of the support cylinder is formed to be longer than the second radial length between the outer circumferential surface of the outer ring and the intersection point.

[0239] <7>

[0240] The gear device according to any one of <1> to <6>, wherein,

[0241] The outer diameter of the inner ring is formed to be larger than the outer diameter of the gear carrier.

[0242] When viewed from the direction along the central axis, a portion of the inner ring is exposed at a position radially outer than the outer circumferential surface of the gear carrier.

Claims

1. A gear mechanism, characterized in that, The gear mechanism has the following features: The housing is configured to rotate about a central axis; A gear carrier is arranged radially inside the housing in a manner that allows it to rotate relative to the central axis; A gear mechanism that reduces rotation from the outside and transmits it to the housing or the gear carrier; as well as The main bearing is disposed between the housing and the gear carrier. The main bearing comprises: The inner ring is located on the gear carrier; Outer ring, which is disposed on the housing; and Multiple rolling elements, held in a rolling manner between the inner and outer rings, rotate about an axis inclined relative to the central axis. The outer ring has a flange portion that restricts the movement of the plurality of rolling elements in the direction along the axis. The flange is positioned radially outward from the plurality of rolling elements and is formed to protrude from the rolling surface of the outer ring toward the axis. Furthermore, the flange portion has a flange surface that contacts the end faces of the plurality of rolling elements. The housing includes a support cylinder that extends along the central axis and covers the outer ring from the radially outer side. The support cylinder covers at least the intersection of the rolling surface and the flange surface from the radially outer side.

2. The gear device according to claim 1, wherein, The support cylinder extends at least along the central axis to the outer end face of the outer ring and covers the entire outer ring from the radially outer side.

3. The gear device according to claim 1 or 2, wherein, When viewed from the direction along the axis of the rolling element, the flange is formed to protrude from the rolling surface toward the axis in such a way that it covers more than 20% of the diameter of the rolling element, and contacts the end face of the rolling element by means of the flange surface.

4. The gear device according to claim 3, wherein, The flange surface does not contact the portion of the end face of the rolling element located on the outer peripheral side of the rolling element.

5. The gear device according to claim 1 or 2, wherein, The support cylinder is in contact with the outer peripheral surface of the outer ring.

6. The gear device according to claim 5, wherein, The first radial length of the support cylinder is formed to be longer than the second radial length between the outer circumferential surface of the outer ring and the intersection point.

7. The gear device according to claim 1 or 2, wherein, The outer diameter of the inner ring is formed to be larger than the outer diameter of the gear carrier. When viewed from the direction along the central axis, a portion of the inner ring is exposed at a position radially outer than the outer circumferential surface of the gear carrier.

Images