Eccentric oscillation type gear unit

Abstract

To provide an eccentric oscillation type gear unit capable of excellently maintaining a lubrication state of a roller during operation of a gear unit.SOLUTION: An eccentric oscillation type gear unit comprises: a crankshaft 14 having an eccentric part; an oscillation gear 16 oscillated by the eccentric part; and a plurality of rollers 18 arranged in a circumferential direction between the eccentric part 12 and the oscillation gear 16. The eccentric part 12 has a recess part 44 formed at a position radially overlapping the rollers 18, and is provided with a guide member 52 that guides lubricant in a lateral space 50, which is on an axially lateral side of the rollers 18, toward the rollers in an axial direction during operation of the gear unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an eccentric swing type gear device.

Background Art

[0002] Patent Document 1 discloses an eccentric swing type gear device including a crankshaft having an eccentric portion, a swing gear that swings by the eccentric portion, and a plurality of rollers arranged in the circumferential direction between the swing gear and the eccentric portion. A recess serving as a lubricant reservoir is formed in the eccentric portion of the crankshaft of Patent Document 1 at a position overlapping the roller in the radial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During the operation of the gear device, due to centrifugal force, the lubricant in the recess of the eccentric portion may continue to accumulate while escaping to the lateral space axially beside the roller. If this state continues during the operation of the gear device, the amount of lubricant contributing to the lubrication of the roller becomes insufficient, which may adversely affect the lubrication state of the roller.

[0005] Therefore, one of the objects of the present disclosure is to provide an eccentric swing type gear device capable of maintaining a good lubrication state of the roller during the operation of the gear device.

Means for Solving the Problems

[0006] The eccentric swing type gear device of the present disclosure includes a crankshaft having an eccentric portion, a swing gear swung by the eccentric portion, and a plurality of rollers arranged circumferentially between the eccentric portion and the swing gear. In the eccentric swing type gear device, a concave portion is formed in the eccentric portion at a position radially overlapping with the roller, and a guide member is provided for guiding a lubricant in a lateral space axially on the side of the roller to the roller side axially during the operation of the gear device.

Advantages of the Invention

[0007] According to the eccentric swing type gear device of the present disclosure, the lubrication state of the roller can be maintained well during the operation of the gear device.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the eccentric swing type gear device (hereinafter, also simply referred to as the gear device) of the present disclosure will be described. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the direction of the reference numerals.

[0010] Refer to FIG. 1. The gear device 10 is incorporated into a driven machine as a part of the driven machine. The driven machine is, for example, various machines such as industrial machines (machine tools, construction machines, etc.), robots (industrial robots, service robots, etc.), transportation equipment (conveyors, vehicles, etc.).

[0011] The gear device 10 includes a crankshaft 14 having at least one eccentric portion 12, a rocking gear 16 rocked by the eccentric portion 12, a plurality of rollers 18 arranged circumferentially between the eccentric portion 12 and the rocking gear 16, a meshing gear 20 meshing with the rocking gear 16, and a casing 22 arranged radially outside the rocking gear 16. In addition, the gear device 10 includes a crankshaft bearing 24 that supports the shaft portion 28 of the crankshaft 14, and a carrier 26 that supports the crankshaft bearing 24. Hereinafter, the direction along the rocking center C16a of the rocking gear 16 is simply referred to as the axial direction, and with respect to the radial direction and the circumferential direction centered on the rocking center C16a, they are simply referred to as the radial direction and the circumferential direction. Also, in this specification, for convenience of explanation, one side in the axial direction (the left side of the paper surface in FIG. 1) is referred to as the output side, and the other side in the axial direction (the right side of the paper surface in FIG. 1) is referred to as the input side.

[0012] The gear device 10 includes an input member to which rotation is input from an external drive source, and an output member that outputs rotation to an external driven member. Here, an example will be described in which the crankshaft 14 is the input member and the output-side carrier 26A described later is the output member. The drive source is, for example, a motor, but in addition to this, a gear motor, an engine, etc. may also be used.

[0013] In this embodiment, a center crank type eccentric swing type gear device 10 will be described. In this type of gear device 10, the aforementioned crankshaft 14 is disposed on the swing center C16a of the swing gear 16. The crankshaft 14 includes, in addition to the eccentric portion 12, shaft portions 28 provided on both axial sides of the eccentric portion 12. The shaft portions 28 continue to the ends of the crankshaft 14 on the side opposite to the eccentric portion 12 in the axial direction. The eccentric portion 12 of the present embodiment is integrally provided by the same member as the shaft portion 28, but may be provided separately from the shaft portion 28. The axis C12 of the eccentric portion 12 is eccentric with respect to the rotation center line C14 of the crankshaft 14. The eccentric portion 12 can swing the swing gear 16 by rotating around the rotation center line C14 of the crankshaft 14. Here, "swing" means that the center line of an element (here, the swing gear 16) mentioned separately from the crankshaft 14 rotates around the swing center C16a. The number of the eccentric portions 12 is not particularly limited, and may be either a single one or three or more.

[0014] In the present embodiment, the swing gear 16 is an external gear, and the meshing gear 20 is an internal gear. The swing gears 16 are provided individually corresponding to the respective plurality of eccentric portions 12, and are supported by the corresponding eccentric portions 12 via a plurality of rollers 18. The meshing gear 20 of the present embodiment is integrated with the casing 22. The casing 22 of the present embodiment is configured by connecting a plurality (here, three) of casing members 22a. A main bearing 30 is disposed between the casing 22 and the carrier 26. The crank bearing 24 and the carrier 26 of the present embodiment are provided on both axial sides with respect to the eccentric portion 12 of the crankshaft 14. Each carrier 26 is connected via a pin body 32 that penetrates the swing gear 16.

[0015] An enclosed space 34 in which a lubricant is enclosed is formed inside the gear device 10. The lubricant of the present embodiment is grease, but lubricating oil or the like may also be used. The lubricant is provided so as to adhere to at least the rollers 18. The enclosed space 34 is sealed by a seal member 36 incorporated in the gear device 10.

[0016] An example of the operation of the above-described gear device 10 will be described. When the crankshaft 14 rotates by the output of the drive source, the oscillating gear 16 oscillates due to the eccentric portion 12 of the crankshaft 14. When the oscillating gear 16 oscillates, the meshing position of the oscillating gear 16 and the meshing gear 20 changes in the circumferential direction. Accordingly, every time the crankshaft 14 makes one revolution, either one of the oscillating gear 16 and the meshing gear 20 (here, the oscillating gear 16) rotates, and the rotation component thereof is taken out by the output member (here, the output-side carrier 26). At this time, with respect to the input rotation input to the crankshaft 14, an output rotation decelerated at a reduction ratio corresponding to the difference in the number of teeth between the oscillating gear 16 and the meshing gear 20 is taken out by the output member.

[0017] Refer to FIG. 2. The plurality of rollers 18 of the present embodiment form part of an eccentric bearing 40 disposed between the eccentric portion 12 of the crankshaft 14 and the oscillating gear 16. The eccentric bearing 40 is a spherical roller bearing. In a spherical roller bearing, there is no spacer for maintaining the interval between adjacent rollers 18 between the respective rollers 18. The plurality of rollers 18 of the spherical roller bearing can be in contact with each other in the circumferential direction. The rotation center line of the roller 18 of the present embodiment extends along the axial direction.

[0018] The eccentric portion 12 of the crankshaft 14 also serves as an inner race on which the roller 18 rolls. In the present embodiment, the outer race on which the roller 18 rolls is provided integrally with the oscillating gear 16 by the same member as the oscillating gear 16, but may be provided separately from the oscillating gear 16. It can be said that the oscillating gear 16 of the present embodiment also serves as an outer race on which the roller 18 rolls.

[0019] A recess 44 is formed in the eccentric portion 12 of the crankshaft 14 at a position overlapping the roller 18 in the radial direction. The recess 44 serves as a lubricant reservoir that can store a lubricant inside itself at least when the gear device 10 is not operating. By storing the lubricant in the recess 44 in advance, during the operation of the gear device 10, the lubricant in the recess 44 can be directly supplied to the roller 18 by the centrifugal force acting due to the rotation of the crankshaft 14. By increasing the amount of lubricant held around the roller 18, it is advantageous for maintaining the lubrication state of the roller 18 over a long period of time.

[0020] The concave portion 44 of the present embodiment is formed at a position axially adjacent to the eccentric portion 12, but may be formed on the outer peripheral surface of the eccentric portion 12. The concave portion 44 of the present embodiment is individually formed at positions axially adjacent to both sides of the eccentric portion 12, but may be formed at a position adjacent to only one side thereof. The concave portion 44 of the present embodiment forms a groove shape extending along the circumferential direction, but its shape is not particularly limited, and it may be formed at intervals in the circumferential direction.

[0021] As an arbitrary configuration, the crankshaft 14 includes a housing groove portion 46 that houses at least a part of the roller 18. In order to satisfy the condition of "housing", it is sufficient that at least a part of both axial ends of the roller 18 is housed in the housing groove portion 46. The housing groove portion 46 is formed so as to extend along the circumferential direction of the crankshaft 14. The housing groove portion 46 includes a pair of inner side surfaces 46a that face the roller 18 in the axial direction. The pair of inner side surfaces 46a regulate the axial movement of the roller 18 by contact with the roller 18 and guide the roller 18 so as to roll along the circumferential direction. The eccentric portion 12 of the crankshaft 14 is provided at the bottom of the housing groove portion 46.

[0022] A lateral space 50 is formed on the axially lateral side with respect to the plurality of rollers 18 inside the gear device 10. The lateral space 50 is formed as a part of the aforementioned enclosed space 34. The lateral space 50 of the present embodiment is individually formed at a position sandwiched between the plurality of rollers 18 on the output side and the crank bearing 24, and at a position axially sandwiched between the plurality of rollers 18 on the input side and the crank bearing 24. In the present embodiment, the lateral space 50 is formed at a position sandwiched between the oscillating gear 16 and the carrier 26 and the crankshaft 14.

[0023] Refer to FIGS. 2 and 3. The gear device 10 includes a guide member 52 that guides a lubricant from the lateral space 50 in the axial direction toward the roller 18 side (hereinafter simply referred to as the "roller side") during the operation of the gear device 10. Here, the "during the operation of the gear device 10" also means when the crankshaft 14 is rotating. The guide member 52 of the present embodiment is individually arranged in each of the lateral spaces 50 on the output side and the input side, but it may be arranged in only one of the lateral spaces 50. The guide member 52 includes an annular portion 54 at least partially arranged in the lateral space 50, a column portion 56 protruding axially from the annular portion 54, and a regulated portion 58 protruding radially outward from the annular portion 54. The guide member 52 is configured, for example, with a resin-based material, a metal-based material, or the like as the material.

[0024] Refer to FIGS. 2 to 4. The guide member 52 includes a guide surface 60 that guides the lubricant in the lateral space 50 toward the roller side in the axial direction. The guide surface 60 of the present embodiment is formed on the inner peripheral portion of the annular portion 54. In the present embodiment, the inner diameter of the guide surface 60 increases as it goes toward the roller side in the axial direction. To achieve this, the illustrated guide surface 60 is tapered, but it may be stepped. At least a part of the guide surface 60 is arranged radially outside the center C18 of the roller 18 when viewed from the axial direction (see FIG. 4). This condition is satisfied by the entire guide surface 60 in the present embodiment. Here, the "center C18" is the outer shape center of the roller 18 when viewed from the axial direction, and in the present embodiment, it is provided on the rotation center line of the roller 18. The guide surface 60 is provided at a position overlapping between the column portion 56 of the guide member 52 and the roller 18 when viewed from the axial direction (for example, the position in the range Sa in FIG. 4), and the lubricant in the lateral space 50 can be guided between them.

[0025] The column portions 56 are provided at intervals in the circumferential direction and are arranged between the rollers 18 adjacent to each other in the circumferential direction. The number of the column portions 56 in the present embodiment is the same as the number of the rollers 18 included in the eccentric bearing 40, but the number is not particularly limited and may be at least less than the number of the rollers 18. The eccentric bearing 40 forms a plurality of roller spaces 62 surrounded by the rolling surfaces 42 (here, the outer rolling surfaces) on which the adjacent rollers 18 roll when viewed from the axial direction. Similar to the rollers 18, the roller spaces 62 are formed to extend along the axial direction. The roller spaces 62 are formed at positions radially shifted from the contact points 18a of the adjacent rollers 18 when viewed from the axial direction. The plurality of column portions 56 are arranged in each of the roller spaces 62 formed by the eccentric bearing 40. By utilizing the roller spaces 62, the column portions 56 can be arranged between the rollers 18 without changing the design of the total roller bearing constituted by the plurality of rollers 18.

[0026] The column portion 56 of the present embodiment includes a rolling surface facing surface 56a facing the rolling surface 42 in the radial direction and a pair of roller facing surfaces 56b facing the roller 18 in the radial direction. The rolling surface facing surface 56a has an arc shape similar to a part of the rolling surface 42. The rolling surface facing surface 56a can be in contact with the rolling surface 42 indirectly or directly via a lubricant. The roller facing surface 56b has an arc shape similar to a part of the outer peripheral surface of the roller 18. The roller facing surface 56b can be in contact with the outer peripheral surface of the roller 18 indirectly or directly via a lubricant.

[0027] The column portion 56 includes a groove inner arrangement portion 56c protruding radially inward from the guide surface 60 of the guide member 52 when viewed from the axial direction. A part of the groove inner arrangement portion 56c is arranged in the accommodation groove portion 46 of the crankshaft 14. The arrangement position of the groove inner arrangement portion 56c in the accommodation groove portion 46 changes so as to progress in the circumferential direction when the guide member 52 swings. In this process, a part of the groove inner arrangement portion 56c repeats a movement such that a part of it enters the accommodation groove portion 46 while another part exits from the accommodation groove portion 46.

[0028] The column portion 56 of this embodiment has a cantilever structure supported by the annular portion 54. The cantilever structure here refers to a structure supported by one annular portion 54 only on one side in its axial direction. It can also be said that the column portion 56 does not have a double-supported structure in which both sides in its axial direction are supported by individual annular portions. As a result, the guide member 52 can be assembled to the eccentric bearing 40 simply by inserting the column portion 56 of the guide member 52 between the adjacent rollers 18 on one axial side of the eccentric bearing 40, and the assembling workability is improved.

[0029] When the column portion 56 has a cantilever structure, the assembling workability is better than that in the case of a double-supported structure. However, as a trade-off, the guide member 52 has low strength. In this regard, in this embodiment, a spherical roller bearing is used as the eccentric bearing 40. Therefore, by dispersing the load acting on one roller 18 to the other rollers 18, the load transmitted from one roller 18 to the column portion 56 of the guide member 52 is reduced. Consequently, even when a guide member 52 with low strength is used, the long life of the guide member 52 can be achieved.

[0030] Referring to FIG. 2, the gear device 10 includes a pair of regulating members 70A and 70B that face each other in the axial direction and regulate the axial movement of the guide member 52. The pair of regulating members 70A and 70B includes a first regulating member 70A disposed on the roller side in the axial direction with respect to the regulated portion 58 of the guide member 52, and a second regulating member 70B disposed on the side opposite to the roller side (the side opposite to the roller 18) in the axial direction with respect to the regulated portion 58. The axial position of the guide member 52 can be held by the pair of regulating members 70A and 70B. In this embodiment, the first regulating member 70A is the oscillating gear 16, and the second regulating member 70B is the outer race 24a of the crank bearing 24. Specific examples of the pair of regulating members 70A and 70B are not particularly limited. For example, these may be a combination of the oscillating gear 16 and the carrier 26, a combination of the crankshaft 14 and the inner race of the crank bearing 24, etc.

[0031] Each of the pair of restricting members 70A and 70B restricts the axial movement of the restricted portion 58 of the guide member 52 and includes restricting surfaces 72A and 72B that face each other in the axial direction. As this restricting surface, the first restricting member 70A includes a first restricting surface 72A, and the second restricting member 70B includes a second restricting surface 72B.

[0032] Refer to FIGS. 2 and 5. In FIG. 5, hatching is applied to the location where the restricted portion 58 of the guide member 52 overlaps with the first restricting surface 72A of the first restricting member 70A, and the second restricting surface 72B of the second restricting member 70B is indicated by a two-dot chain line. Also, double hatching is applied to the location sandwiched between the first restricting surface 72A and the second restricting surface 72B.

[0033] The restricted portion 58 of the guide member 52 is provided radially outside of the roller 18 that is axially adjacent to the guide member 52. A part of the restricted portion 58 (the location of the double hatching in FIG. 5) is disposed between the restricting surfaces 72A and 72B within the first circumferential range 74 around the eccentric portion 12. The other part of the restricted portion 58 is disposed at a position radially inwardly displaced from between the restricting surfaces 72A and 72B within the second circumferential range 76 around the eccentric portion 12. The first circumferential range 74 includes the location 78 in the restricted portion 58 that is in the maximum eccentricity direction D1 of the eccentric portion 12. The second circumferential range 76 includes the location 80 in the restricted portion 58 that is in the anti-maximum eccentricity direction D2 of the eccentric portion 12. Here, the eccentric portion 12 refers to the eccentric portion 12 that swings the guide member 52, and the circumferential range around the eccentric portion 12 refers to the circumferential range centered on the axis C12 of the eccentric portion 12. Also, the maximum eccentricity direction D1 refers to the direction from the rotation center line C14 of the crankshaft 14 toward the axis C12 of the eccentric portion 12. The anti-maximum eccentricity direction D2 refers to the direction that is exactly opposite to the maximum eccentricity direction D1 with respect to the rotation center line C14.

[0034] The restricted portion 58 of the guide member 52 is guided in the circumferential direction by a pair of restricting members 70A and 70B when the guide member 52 swings due to the eccentric portion 12 of the crankshaft 14. At this time, the restricted portion 58 of the guide member 52 is guided while sliding along at least one of the first restricting member 70A and the second restricting member 70B. Thereby, the guide member 52 can be swung while maintaining its axial position. In particular, even when the column portion 56 of the guide member 52 has a cantilever structure, it is effective in that the column portion 56 does not come out from between the adjacent rollers 18 during the swinging process of the guide member 52.

[0035] The operation regarding the above guide member 52 will be described. When the crankshaft 14 rotates, the eccentric portion 12 of the crankshaft 14 causes each roller 18 to swing together with the swing gear 16. At this time, the guide member 52 also swings due to the eccentric portion 12 of the crankshaft 14. In order to achieve this, in the present embodiment, the column portion 56 of the guide member 52 is arranged between the adjacent rollers 18, and the guide member 52 can swing together with each roller 18. When each roller 18 revolves around the axis C12 of the eccentric portion 12, the guide member 52 can rotate around its axis C12 by being pushed by each roller 18.

[0036] Referring to FIG. 6(A), when the crankshaft 14 rotates, the centrifugal force acts on the lubricant because the lubricant tries to rotate together with the crankshaft 14, and the lubricant tries to flow in the direction D3 toward the radially outer side. Here, during the operation of the gear device 10, the guide member 52 guides the lubricant in the lateral space 50 that tries to flow radially outward due to the centrifugal force in the axial direction toward the roller 18 side in the direction D4 by its guide surface 60. At this time, as described above, the guide surface 60 guides the lubricant between the column portion 56 of the guide member 52 and the roller 18.

[0037] Refer to FIG. 6(B). The guide member 52 of the present embodiment is swingable by the eccentric portion 12 of the crankshaft 14. As a result, a part of the guide surface 60 of the guide member 52 repeats a movement of moving toward the radially inner direction D5 and then moving toward the radially outer side. When a part of the guide surface 60 moves in the direction D5 toward the radially inner side in this way, the lubricant is also guided axially toward the roller side in the side space 50 by pushing the lubricant axially toward the roller side in the direction D6 by the guide surface 60. Thereby, compared with the case where the guide member 52 does not swing, the amount of lubricant that can be guided axially toward the roller side by the guide member 52 can be increased.

[0038] The effects of the above-described gear device 10 will be described. During the operation of the gear device 10, due to centrifugal force, the lubricant in the concave portion 44 of the eccentric portion 12 may escape to the side space 50 axially lateral to the roller 18. This problem can occur when the lubricant in the concave portion 44 is discharged radially outward by centrifugal force and then pushed out axially by the roller 18.

[0039] Here, according to the present embodiment, even if the lubricant escapes to the side space 50 during the operation of the gear device 10, the guide member 52 can guide the lubricant that has escaped to the side space 50 axially toward the roller side. Therefore, by returning the lubricant that has escaped to the side space 50 around the roller 18, the amount of lubricant contributing to the lubrication of the roller 18 can be ensured, and the lubrication state of the roller 18 can be maintained well during the operation of the gear device 10. If the amount of lubricant around the roller 18 becomes insufficient, in addition to the roller 18, there is a risk of wear due to oil film rupture on the rolling surface on which the roller 18 rolls. In this regard, by ensuring the amount of lubricant contributing to the lubrication of the roller 18, wear of the roller 18 and the like due to oil film rupture can be suppressed during the operation of the gear device 10.

[0040] The guide surface 60 of the guide member 52 guides the lubricant between the column portion 56 and the roller 18. Thus, the lubricant can reach far in the axial direction via the space between the column portion 56 and the roller 18, and the lubricant can be retained between them. As a result, the lubricant guided by the guide member 52 can be retained between the column portion 56 and the roller 18 in a wide axial range over a long period of time, and the lubrication state of the roller 18 can be maintained even better. In this way, in order to retain the lubricant between the column portion 56 and the roller 18, a plurality of recesses serving as lubricant reservoirs may be formed in the roller contact surface 56b of the column portion 56. The plurality of recesses are formed, for example, by dimpling or the like. In order to make the lubricant reach far by the column portion 56 of the guide member 52, the column portion 56 is preferably provided at a position overlapping the recess 44 of the eccentric portion 12 when viewed in the radial direction. In order to satisfy this condition, when there are a plurality of recesses 44 in the eccentric portion 12, the column portion 56 is preferably provided at a position overlapping at least one recess 44 on the guide surface 60 side of the guide member 52, and more preferably at a position overlapping two recesses 44. Also, in order to make the lubricant reach far, the column portion 56 is preferably provided at a position overlapping the axial center position of the roller 18 when viewed in the radial direction, and more preferably at a position overlapping the end portion of the roller 18 on the side opposite to the guide surface 60 with respect to the axial center position.

[0041] Next, other features of the gear device 10 will be described. Refer to FIG. 2. Let the axial dimension of the first clearance 82 provided between the accommodation groove portion 46 of the crankshaft 14 and the groove inner arrangement portion 56c of the guide member 52 be δ1 (mm). The first clearance 82 is provided to allow axial relative movement of the guide member 52 with respect to the crankshaft 14. The axial dimension δ1 is obtained by subtracting the axial dimension L56c of the groove inner arrangement portion 56c of the guide member 52 from the axial dimension L46c between a pair of inner surfaces 46a in the accommodation groove portion 46 of the crankshaft 14. The axial dimension L46c of the accommodation groove portion 46 refers to the minimum axial dimension at the location where the axial movement of the groove inner arrangement portion 56c is restricted by the pair of inner surfaces 46a. The axial dimension L56c of the groove inner arrangement portion 56c refers to the maximum axial dimension at the location where the axial movement is restricted by contact with the pair of inner surfaces 46a in the groove inner arrangement portion 56c.

[0042] Let the axial dimension of the second clearance 84 provided between the pair of regulating members 70A and 70B and the regulated portion 58 of the guide member 52 be δ2 (mm). Here, an example is shown where the second clearance 84 is very small and does not appear in the figure. The second clearance 84 is provided to allow axial relative movement of the guide member 52 with respect to the pair of regulating members 70A and 70B. The axial dimension δ2 is obtained by subtracting the axial dimension L58 of the regulated portion 58 of the guide member 52 from the axial dimension L72 between the regulating surfaces 72A and 72B of the pair of regulating members 70A and 70B. The axial dimension L70 of the pair of regulating members 70A and 70B refers to the minimum axial dimension at the location where the axial movement of the regulated portion 58 is restricted by the regulating surfaces 72A and 72B. The axial dimension L58 of the regulated portion 58 refers to the maximum axial dimension at the location where the axial movement is restricted by contact with the regulating surfaces 72A and 72B in the regulated portion 58.

[0043] At this time, the axial dimension δ2 of the second clearance 84 is smaller than the axial dimension δ1 of the first clearance 82. That is, δ1 > δ2. As a result, when the guide member 52 is tilted axially due to a moment or the like applied to the guide member 52, the restricted portion 58 thereof contacts one of the restricting members 70A and 70B before the groove inner arrangement portion 56c of the guide member 52 contacts the inner surface 46a of the accommodation groove portion 46, thereby preventing the tilt. If the guide member 52 is tilted greatly axially, a part of the groove inner arrangement portion 56c thereof is likely to be caught between the oscillating gear 16 and the opening peripheral edge portion of the accommodation groove portion 46 in the process of trying to enter the accommodation groove portion 46. In this regard, according to the present embodiment, since a large tilt of the guide member 52 can be prevented, it is difficult for the groove inner arrangement portion 56c of the guide member 52 to be caught, and the oscillating motion of the guide member 52 can be made smooth. In addition, on the premise of δ1 > δ2, the axial dimension δ2 of the second clearance 84 may be zero. Further, the magnitude relationship between the axial dimensions δ1 and δ2 of each clearance is not particularly limited. They may be the same, or δ1 < δ2 may be satisfied.

[0044] The crankshaft 14 is provided on the outer peripheral portion of the crankshaft 14 and includes an opposing surface 86 that is radially opposed to the guide surface 60 of the guide member 52. As described above, the guide surface 60 has an increasing inner diameter as it goes toward the roller side in the axial direction. The opposing surface 86 has an increasing outer diameter as it goes toward the roller side in the axial direction. In order to achieve this, the opposing surface 86 is tapered in the present embodiment, but may be stepped. Thereby, when the guide member 52 oscillates, the guide surface 60 of the guide member 52 can be brought closer to the opposing surface 86 until they overlap axially (see FIG. 6(B)). As a result, the lubricant between the two can be guided to the roller 18 side by the guide surface 60 as much as possible. The shape of the opposing surface 86 is not particularly limited. For example, the opposing surface 86 may be formed to extend flatly along the axial direction.

[0045] Refer to FIGS. 6(A) and 6(B). Pay attention to the movement of the restricted portion 58 of the guide member 52 during the process of swinging by the eccentric portion 12. During this process, a part of the restricted portion 58 first approaches radially until it axially overlaps with a part of the second restricting surface 72B of the second restricting member 70B, and then repeatedly moves radially away so as not to axially overlap with a part of the second restricting surface 72B. Thus, when the restricted portion 58 of the guide member 52 is at a position where it does not axially overlap with a part of the second restricting surface 72B (see FIG. 6(B)), the axial movement of a part of the restricted portion 58 is no longer restricted by a part of the second restricting surface 72B. Accordingly, a part of the restricted portion 58 may be axially displaced toward the second restricting surface 72B side. If such displacement occurs, there is a risk that the restricted portion 58 of the guide member 52 may hit the second restricting member 70B when the restricted portion 58 approaches the second restricting surface 72B in the radial direction.

[0046] Here, an inclined surface 90 is provided at a location on the restricted portion 58 of the guide member 52 that axially faces the second restricting surface 72B. The inclined surface 90 extends so as to axially move away from the second restricting surface 72B as it goes radially outward. Consider the case where the guide member 52 is slightly axially displaced toward the second restricting surface 72B side and the restricted portion 58 of the guide member 52 approaches the second restricting surface 72B in the radial direction. At this time, when the inclined surface 90 hits the second restricting member 70B, a part of the restricted portion 58 can be guided to the side opposite to the second restricting surface 72B in the axial direction (the right side of the drawing in the figure). As a result, by eliminating this displacement, the swinging operation of the guide member 52 can be made smooth.

[0047] The above-described modified forms of the gear device will be explained. As an example of the specific type of the eccentric swing type gear device, the center crank type was described. This type is not particularly limited. For example, a distribution type in which a plurality of crank shafts 14 are arranged at positions offset from the swing center C16a of the swing gear 16 may also be used.

[0048] Instead of the carrier 26, the casing 22 may serve as the output member. Instead of the external gear, an internal gear may be used as the oscillating gear 16, and instead of the internal gear, an external gear may be used as the meshing gear 20. The gear device 10 may function as a speed increasing device. In this case, instead of the crankshaft 14, the carrier 26 or the casing 22 may be the input member, and instead of the carrier 26 or the casing 22, the crankshaft 14 may be the output member.

[0049] The specific example of the eccentric bearing 40 is not limited to the spherical roller bearing. The eccentric bearing 40 may be a roller bearing in which a spacer and a part of a cage are arranged between adjacent rollers 18. It can also be said that adjacent rollers 18 do not have to contact each other.

[0050] The guide member 52 does not have to include the column portion 56. The column portion 56 of the guide member 52 may have a both-end supported structure. The guide member 52 does not have to include the restricted portion 58. Even when the guide member 52 does not swing by the eccentric portion 12 of the crankshaft 14, the guide member 52 may include the restricted portion 58. The guide surface 60 of the guide member 52 may be arranged radially inward of the center C18 of the roller 18 when viewed from the axial direction. The space 62 between the rollers where the column portion 56 is arranged has been described by way of example as being formed by being surrounded by adjacent rollers 18 and the outer rolling surface 42 when viewed from the axial direction. In addition to this, the space 62 between the rollers may be formed by being surrounded by adjacent rollers 18 and the inner rolling surface on which the roller rolls.

[0051] The guide member 52 does not have to swing by the eccentric portion 12 of the crankshaft 14. Also in this case, the guide member 52 may guide the lubricant between the column portion 56 of the guide member 52 and the roller 18. The specific example for swinging the guide member 52 is not particularly limited. For example, by integrating the oscillating gear 16 and the guide member 52, the guide member 52 may be swung together with the oscillating gear 16. It can also be said that the guide member 52 may be swingable together with either the eccentric bearing 40 or the oscillating gear 16.

[0052] The above embodiments and modified forms are illustrative. The technical ideas abstracted from these should not be construed as being limited to the contents of the embodiments and modified forms. Many design changes such as changes, additions, deletions, etc. of components are possible for the contents of the embodiments and modified forms. In the foregoing embodiments, with respect to the contents for which such design changes are possible, the notation "embodiment" is attached and emphasized. However, design changes are also permitted for the contents without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached. Structures and numerical values mentioned in the embodiments and modified forms naturally include those that can be regarded as the same considering manufacturing errors and the like.

[0053] Components configured by a single member in the embodiment may be configured by a plurality of members. Similarly, components configured by a plurality of members in the embodiment may be configured by a single member. For example, although an example in which the guide member 52 is configured by a single member is shown, it may be configured by a plurality of members.

Description of Reference Numerals

[0054] 10... Eccentric swing type gear device, 12... Eccentric portion, 14... Crankshaft, 16... Swing gear, 44... Concave portion, 46... Accommodating groove portion, 50... Lateral space, 52... Guide member, 54... Annular portion, 56... Column portion, 56b... Opposing surface, 56c... Portion arranged in the groove, 58... Restricted portion, 60... Guide surface, 62... Roller space, 70A, 70B... Restricting members, 82... First clearance, 84... Second clearance, 86... Opposing surface.

Claims

1. A crankshaft having an eccentric portion, A swing gear swung by the eccentric portion, A plurality of rollers arranged circumferentially between the eccentric portion and the swing gear, and an eccentric swing type gear device comprising: A concave portion is formed in the eccentric portion at a position radially overlapping the roller, An eccentric swing type gear device comprising a guide member for guiding a lubricant in a side space axially lateral to the roller axially toward the roller during operation of the gear device.

2. The guide member is the eccentric swing type gear device according to claim 1 swung by the eccentric portion.

3. The guide member includes a column portion disposed between the rollers adjacent to each other in the circumferential direction and a guide surface for guiding the lubricant axially toward the roller side, The guide surface is the eccentric swing type gear device according to claim 1 for guiding the lubricant between the roller and the column portion.

4. The guide member includes an annular portion at least partially disposed in the side space, The column portion is a cantilever structure supported by the annular portion, and the eccentric swing type gear device according to claim 3.

5. The plurality of rollers are circumferentially contactable with each other, and the eccentric swing type gear device according to claim 4.

6. The column portion is disposed in a roller space surrounded by the rollers adjacent to each other in the circumferential direction and a rolling surface on which the rollers roll, and the eccentric swing type gear device according to claim 5.

7. The guide member includes a regulated portion whose axial movement is regulated by a pair of regulating members facing each other in the axial direction, and the eccentric swing type gear device according to claim 1.

8. The regulated portion is circumferentially guided by the pair of regulating members when the guide member swings due to the eccentric portion, and the eccentric swing type gear device according to claim 7.

9. The regulated portion is provided radially outside the roller, The regulated portion is disposed between the pair of regulating members in a circumferential range around the eccentric portion including a location in the maximum eccentric direction of the eccentric portion, and the eccentric swing type gear device according to claim 8.

10. The crankshaft includes a housing groove portion for housing at least a part of the roller, The guide member includes a groove inner arrangement portion disposed in the housing groove portion, When the axial dimension of a first clearance provided between the housing groove portion and the groove inner arrangement portion is δ1 and the axial dimension of a second clearance provided between the pair of regulating members and the regulated portion is δ2, The eccentric swing type gear device according to claim 7, wherein the axial dimension δ2 is smaller than the axial dimension δ1.

11. The guide member includes a guide surface that guides a lubricant toward the roller side in the axial direction. The eccentric swing type gear device according to claim 1, wherein the inner diameter of the guide surface increases as it goes toward the roller side in the axial direction.

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