Eccentric swing type reduction gear

Abstract

To provide an eccentric oscillation type speed reducer in which a roller of an eccentric body bearing is hard to come off.SOLUTION: An eccentric oscillation type speed reducer 100 is equipped with a crank shaft 12 having eccentric portions 12a and 12b, crank shaft bearings 30 and 32 supporting the crank shaft 12, and eccentric body bearings 34 and 36 disposed on the outer side in diametrical directions of the eccentric portions 12a and 12b. The eccentric body bearings 34 and 36 are full type roller bearings, and the eccentric portions 12a and 12b are depressed on a counter eccentric direction side. Rollers 34a and 36a of the eccentric bearings 34 and 36 have outer diameters of axial outer end portions that are smaller than outer diameters of axial center portion, and have coming-off preventive portions 26, 27, and 28 disposed on an outer periphery of the crank shaft 12 to restrict the movement in the axial direction of the rollers 34a and 36a. The coming-off preventive portions 26, 27, and 28 are provided separately from the crank shaft 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an eccentric swing type reduction gear.

Background Art

[0002] Patent Document 1 describes a differential reduction gear that employs a full complement needle bearing as a bearing for an eccentric portion. This reduction gear includes an output shaft supported within a casing, an internal gear, an input shaft that passes through the output shaft and the internal gear coaxially and is supported via a ball bearing, a bearing for the eccentric portion, an external gear that is inscribed in and meshes with the internal gear, and a carrier that is connected to the output shaft via a pin member that loosely inserts the external gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the reduction gear described in Patent Document 1, the external gear is externally fitted to the eccentric portion of the input shaft via a bearing for the eccentric portion, which is a full complement needle bearing. Also, the outer diameter of the eccentric portion of the input shaft is smaller than the outer diameter of the shaft support portion where the ball bearing is provided. Thus, when the outer diameter of the eccentric portion of the input shaft is smaller than the outer diameter of the shaft support portion, when incorporating the external gear, it is necessary to prevent the inner diameter of the external gear from interfering with the crankshaft. Therefore, the axial regulating portion of the roller of the bearing for the eccentric portion cannot be made too large in the radial direction. Accordingly, the roller of the bearing for the eccentric portion is likely to come off toward the shaft support side.

[0005] An object of the present invention is to provide an eccentric swing type reduction gear in which the roller of the eccentric body bearing is difficult to come off, in view of such problems.

Means for Solving the Problems

[0006] To solve the above problems, an eccentric swing type reduction gear according to an aspect of the present invention includes a crankshaft having an eccentric portion, a crankshaft bearing that supports the crankshaft, and an eccentric body bearing disposed on the radially outer side of the eccentric portion. The eccentric body bearing is a spherical roller bearing, the eccentric portion is recessed on the anti-eccentric direction side, the rollers of the eccentric body bearing have an outer diameter of the axially outer end portion smaller than the outer diameter of the axially central portion, and the crankshaft is provided with a retaining portion disposed on the outer periphery thereof to restrict the axial movement of the rollers. The retaining portion is provided separately from the crankshaft.

[0007] In addition, any combination of the above components, or those obtained by mutually replacing the components and expressions of the present invention among methods, systems, etc. are also effective as aspects of the present invention.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an eccentric swing type reduction gear in which the rollers of the eccentric body bearing are difficult to come off.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. In the embodiments and modifications, the same or equivalent components and members are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Also, the dimensions of the members in each drawing are shown enlarged or reduced as appropriate for easy understanding. Further, some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0011] Also, terms including ordinals such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from another, and the components are not limited by this term.

[0012] [First Embodiment] Hereinafter, with reference to FIGS. 1 and 2, the configuration of an eccentric swing type speed reduction device 100 (hereinafter, may be simply referred to as "speed reduction device 100") according to the first embodiment of the present disclosure will be described. FIG. 1 is a side cross-sectional view schematically showing the speed reduction device 100. The use of the speed reduction device 100 is not limited, and the speed reduction device 100 in this example can be used for various purposes such as robots.

[0013] The overall configuration of the speed reduction device 100 will be described. The speed reduction device 100 mainly includes a crankshaft 12, external gears 14 and 15, an internal gear 16, carriers 18 and 20, a casing 22, a main bearing 24, retaining parts 26, 27 and 28, crankshaft bearings 30 and 32, eccentric body bearings 34 and 36, and an inner pin 38. The speed reduction device 100 is a center crank type planetary gear device that swings the external gears 14 and 15 via the eccentric body bearings 34 and 36 by the rotation of the crankshaft 12 and transmits the rotation of the external gears 14 and 15 to the carriers 18 and 20 via the inner pin 38.

[0014] Hereinafter, the direction along the central axis La of the internal gear 16 is referred to as the "axial direction", and the circumferential direction and the radial direction of the circle centered on the central axis La are referred to as the "circumferential direction" and the "radial direction", respectively. Also, hereinafter, for convenience, one side in the axial direction (the right side in the figure) is referred to as the input side, and the other side (the left side in the figure) is referred to as the anti-input side. Such notation of directions does not limit the usage posture of the speed reduction device 100, and the speed reduction device 100 can be used in any posture.

[0015] The speed reduction device 100 of the present embodiment functions as a center crank type eccentric swing type speed reducer in which the crankshaft 12 is provided on the same axis as the central axis La of the internal gear 16. The speed reduction device 100 has a hollow portion H that penetrates axially in the central portion.

[0016] The crankshaft 12 has a hollow cylindrical shape with a hollow portion H at the center. For example, a motor shaft is connected to the input side end of the crankshaft 12 by a connector such as a bolt. The crankshaft 12 has a plurality of eccentric portions and functions as an eccentric body that swings an external gear. In the present embodiment, the crankshaft 12 has two eccentric portions 12a and 12b that are 180° out of phase.

[0017] The eccentric portions 12a and 12b include a first eccentric portion 12a and a second eccentric portion 12b provided on the input side of the first eccentric portion 12a. The direction in which each outer peripheral surface of the eccentric portions 12a and 12b is farthest from the central axis La in the radial direction is referred to as the eccentric direction, and the direction opposite to the eccentric direction is referred to as the anti-eccentric direction. That is, the outer peripheral surface of the eccentric portions 12a and 12b in the anti-eccentric direction is the portion closest to the central axis La in the radial direction. In FIG. 1, the eccentric direction of the first eccentric portion 12a is the upward direction in the figure, and the eccentric direction of the second eccentric portion 12b is the downward direction in the figure. The eccentric portions 12a and 12b protrude toward the eccentric direction side and are recessed on the anti-eccentric direction side. The number of eccentric portions is not limited to 2, and may be 1 or 3 or more. Here, being recessed on the anti-eccentric direction side means that a predetermined range including the anti-eccentric direction position (the position 180 degrees from the maximum eccentric direction position) is recessed (the distance to the central axis La is smaller than that of the adjacent shaft support portions), and the recessed range is not particularly limited. For example, in the present embodiment, it is recessed in the range of ±45 degrees from the anti-eccentric direction.

[0018] Refer also to FIG. 2. FIG. 2 is a cross-sectional view showing the crankshaft 12. The crankshaft 12 is supported by the carriers 18 and 20 and the casing 22 via the crankshaft bearings 30 and 32. The crankshaft 12 has shaft support portions 12c and 12d supported by the crankshaft bearings 30 and 32. The shaft support portions 12c and 12d include a first shaft support portion 12c provided on the anti-input side of the eccentric portion 12a and a second shaft support portion 12d provided on the input side of the eccentric portion 12b. A first crankshaft bearing 30 described later is externally fitted to the first shaft support portion 12c, and a second crankshaft bearing 32 described later is externally fitted to the second shaft support portion 12d.

[0019] The crankshaft bearings 30 and 32 support the crankshaft 12. The crankshaft bearings 30 and 32 include a first crankshaft bearing 30 disposed on the anti-input side of the external gear wheels 14 and 15 and a second crankshaft bearing 32 disposed on the input side of the external gear wheels 14 and 15. There is no limitation on the configuration of the crankshaft bearings 30 and 32, but the rolling elements of the crankshaft bearings 30 and 32 in this example are spherical bodies.

[0020] The first crankshaft bearing 30 is externally fitted to the crankshaft 12 and is restricted from moving toward the non-input side by a washer 41 that is engaged with the outer peripheral groove of the crankshaft 12. The second crankshaft bearing 32 is externally fitted to the crankshaft 12 and is restricted from moving toward the input side by a washer 42 that is engaged with the outer peripheral groove provided in the crankshaft 12 and a washer 43 that is engaged with the inner peripheral groove provided in the bearing support hole 22h of the fourth casing 22d described later.

[0021] A first oil seal 45 is provided adjacent to the non-input side of the first crankshaft bearing 30 with the washer 41 interposed therebetween. A second oil seal 46 is provided adjacent to the input side of the second crankshaft bearing 32 with the washers 42 and 43 interposed therebetween. The first oil seal 45 is disposed between the radially central hole 18h of the first carrier 18 described later and the crankshaft 12. The second oil seal 46 is disposed between the bearing support hole 22h of the fourth casing 22d and the crankshaft 12.

[0022] The eccentric body bearings 34 and 36 are disposed between the eccentric portions 12a and 12b and the external gear wheels 14 and 15. The eccentric body bearings 34 and 36 include a first eccentric body bearing 34 disposed on the outer periphery of the first eccentric portion 12a and a second eccentric body bearing 36 disposed on the outer periphery of the second eccentric portion 12b. The eccentric body bearings 34 and 36 are spherical roller bearings having a plurality of rollers 34a and 36a as rolling elements. Here, a spherical roller bearing refers to a bearing that does not have a cage (retainer) that restricts the circumferential contact between adjacent rollers in the circumferential direction (restricts the circumferential position of each roller).

[0023] The external gear wheels 14 and 15 include a first external gear wheel 14 disposed on the outer periphery of the first eccentric body bearing 34 and a second external gear wheel 15 disposed on the outer periphery of the second eccentric body bearing 36. The carriers 18 and 20 include a first carrier 18 disposed on the non-input side of the external gear wheels 14 and 15 and a second carrier 20 disposed on the input side of the external gear wheels 14 and 15.

[0024] The external gear wheels 14 and 15 are rotatably supported on the corresponding eccentric portions 12a and 12b via eccentric bearings 34 and 36. The external gear wheels 14 and 15 are formed with central holes 14c and 15c and a plurality of inner pin holes 14h and 15h. The central holes 14c and 15c are through holes provided at the centers of the external gear wheels 14 and 15. The plurality of inner pin holes 14h and 15h are through holes provided at positions offset from the centers of the external gear wheels 14 and 15. In the example of FIG. 1, a plurality (for example, six) of inner pin holes 14h and 15h are arranged at predetermined intervals (for example, 60°) in the circumferential direction. Inner pins 38 are inserted into the inner pin holes 14h and 15h. The teeth formed on the outer circumferences of the external gear wheels 14 and 15 rotate while meshing with the teeth of the internal gear wheel 16, causing the external gear wheels 14 and 15 to swing.

[0025] The internal gear wheel 16 meshes with the external gear wheels 14 and 15. The internal gear wheel 16 of the present embodiment includes an internal gear wheel main body 16b integrated on the inner circumferential side of a casing 22 (a third casing 22c described later), and an external pin 16a (pin member) rotatably supported on the internal gear wheel main body 16b. The external pin 16a constitutes the internal teeth of the internal gear wheel 16. The number of internal teeth of the internal gear wheel 16 (the number of external pins 16a) is slightly (by one in this example) more than the number of external teeth of the external gear wheels 14 and 15. The input-side end of the external pin 16a is restricted from axial movement by the anti-input-side surface of a fourth casing 22d described later.

[0026] The anti-input-side end of the external pin 16a is restricted from axial movement by the input-side surface of a regulating washer 40. The regulating washer 40 is a hollow disk-shaped member whose outer peripheral portion is sandwiched between a second casing 22b and a third casing 22c described later.

[0027] The carriers 18 and 20 are circular members. The first carrier 18 supports the end portion on the anti-input side of the crankshaft 12 via the first crankshaft bearing 30. The first carrier 18 has a radially central hole 18h and a plurality of through holes 18p. The radially central hole 18h supports the first crankshaft bearing 30. The plurality (for example, six) of through holes 18p are provided at positions offset radially from the central axis La at a predetermined interval (for example, 60°) in the circumferential direction.

[0028] The second carrier 20 supports the end portion on the input side of the crankshaft 12 via the second crankshaft bearing 32. The second carrier 20 has a radially central hole 20h and a plurality of through holes 20p. The radially central hole 20h supports the second crankshaft bearing 32. The plurality (for example, six) of through holes 20p are provided at positions offset radially from the central axis La at a predetermined interval (for example, 60°) in the circumferential direction.

[0029] The first carrier 18 and the second carrier 20 are connected by an inner pin 38 inserted through the through holes 18p and 20p. In this example, the second carrier 20 functions as an inner pin support member that supports the input side of the inner pin 38.

[0030] One of the first carrier 18 and the casing 22 functions as an output member that outputs rotational power to a driven device (not shown), and the other functions as a fixed member that is fixed to an external member for supporting the speed reduction device 100. In the present embodiment, the output member is the first carrier 18, and the fixed member is the casing 22. Bolt holes 18c for connecting the driven device are provided on the end face on the anti-input side of the first carrier 18.

[0031] The inner pins 38 penetrate axially through the inner pin holes 14h and 15h of the external gear wheels 14 and 15 at positions radially offset from the axial centers of the external gear wheels 14 and 15. In this example, a plurality (for example, six) of inner pins 38 are arranged at predetermined intervals in the circumferential direction. In FIG. 1, one inner pin 38 is shown. The inner pin 38 is inserted into the through hole 18p of the first carrier 18 from the anti-input side, passes through the inner pin holes 14h and 15h, and fits into the through hole 20p of the second carrier 20, thereby being a connecting pin that connects the first carrier 18 and the second carrier 20.

[0032] A sleeve 38s is rotatably fitted on the outer periphery of the inner pin 38. The sleeve 38s is inserted into the inner pin holes 14h and 15h with a gap. The inner pin 38 abuts against a part of the inner pin holes 14h and 15h via the sleeve 38s. The inner pin 38 restrains the rotation of the external gear wheels 14 and 15 and allows only their rocking. With this configuration, the carriers 18 and 20 move in synchronization with the rotation of the external gear wheels 14 and 15 via the inner pin 38.

[0033] The casing 22 constitutes the outer shell of the speed reduction device 100. The casing 22 includes a first casing 22a, a second casing 22b, a third casing 22c, and a fourth casing 22d that are laminated in this order from the anti-input side toward the input side. The first casing 22a, the second casing 22b, and the third casing 22c are hollow cylindrical members. The fourth casing 22d is a substantially disc-shaped member having a bearing support hole 22h at the radial center.

[0034] The first casing 22a and the second casing 22b mainly surround the first carrier 18. The third casing 22c mainly surrounds the external gear wheels 14 and 15. An internal gear 16 is provided on the inner peripheral surface of the third casing 22c. The fourth casing 22d mainly covers the outer peripheral surface and the input side surface of the second carrier 20. The bearing support hole 22h of the fourth casing 22d is an axially through hole that supports the second crankshaft bearing 32.

[0035] The first casing 22a, the second casing 22b, and the third casing 22c are fixed by bolts B1. The bolts B1 penetrate the first casing 22a and the second casing 22b from the non-input side and are screwed into the threaded holes 22m of the third casing 22c. The fourth casing 22d is fixed to the third casing 22c by bolts B2. The bolts B2 penetrate the fourth casing 22d from the input side and are screwed into the threaded holes 22n of the third casing 22c. With this configuration, the casings 22 are integrated.

[0036] The main bearing 24 is disposed on the non-input side of the external gear teeth 14, 15. The main bearing 24 is disposed between the first carrier 18 and the casing 22. Although there is no limitation on the configuration of the main bearing 24, the main bearing 24 in this example is a crossed roller bearing. The outer ring of the main bearing 24 is integrally formed with the first casing 22a and the second casing 22b. The inner ring of the main bearing 24 is integrally formed with the carrier 18. The main bearing 24 rotatably supports the first carrier 18 with respect to the casing 22.

[0037] Referring to FIGS. 1 and 2, the characteristic configuration of this embodiment will be described. FIG. 2 is a cross-sectional view showing the crankshaft 12. In order to increase the strength of the eccentric bearings 34, 36, it is conceivable to increase the diameter of the rollers 34a, 36a of the eccentric bearings 34, 36. However, simply increasing the diameter of the rollers will correspondingly increase the size of the speed reducer 100. Therefore, in this embodiment, the first outer diameter D1 of the eccentric portions 12a, 12b of the crankshaft 12 is smaller than the second outer diameter D2 of the shaft support portions 12c, 12d supported by the crankshaft bearings 30, 32 of the crankshaft 12. Since the first outer diameter D1 is small, even if the diameter of the rollers 34a, 36a is increased, an increase in the size of the device can be suppressed.

[0038] If the diameters of the eccentric portions 12a and 12b are reduced, the strength of the crankshaft 12 may decrease. In particular, stress may concentrate at the corners of the regions recessed in the anti-eccentric direction of the eccentric portions 12a and 12b (hereinafter referred to as "concave corners"). In the example of FIG. 2, in order to disperse the stress at the concave corners, the bent portion 12k is provided in the region recessed in the anti-eccentric direction of the eccentric portions 12a and 12b. The bent portion 12k is a portion that is connected by a curve from the first opposing surface 12u that axially opposes the rollers 34a and 36a to the second opposing surface 12v that radially opposes the rollers 34a and 36a in the region in the anti-eccentric direction of the eccentric portions 12a and 12b.

[0039] Also, curved surfaces 34k and 36k are provided at the axial ends of the rollers 34a and 36a to avoid interference with the bent portion 12k. The bent portion 12k and the curved surfaces 34k and 36k may have various shapes including a curved surface, a flat surface, a composite surface of a curved surface and a flat surface, etc. in addition to an R shape. The shapes of the bent portion 12k and the curved surfaces 34k and 36k can be set by simulation according to the desired strength.

[0040] As shown in FIG. 2, the outer diameters De of the axial ends of the rollers 34a and 36a of the eccentric body bearings 34 and 36 are smaller than the outer diameter Dc of the axial center portion. In this case, the rollers 34a and 36a can avoid interference with the bent portion 12k.

[0041] Preferably, the outer diameter De of the axial ends of the rollers 34a and 36a may be 20% or less of the outer diameter Dc of the axial center portion of the rollers 34a and 36a. In this case, even when the curvature radius of the bent portion 12k is large, interference with the bent portion 12k can be avoided. Also, the axial ends of the rollers 34a and 36a do not have to have a flat surface perpendicular to the axial direction (the outer diameter De is zero). As an example, the axial ends of the rollers 34a and 36a may be spherical surfaces with a constant curvature radius, or may even be hemispherical, or may be curved surfaces with a non-constant curvature radius. In this case, the sliding resistance with the retaining portions 26, 27, and 28 of the rollers 34a and 36a can be reduced.

[0042] When the curved surface portions 34k and 36k are provided on the rollers 34a and 36a, the possibility of the rollers 34a and 36a coming off toward the crankshaft bearings 30 and 32 increases. Further, since the sliding counterparts of the roller end faces change among the external gear, the eccentric portion, and the adjacent roller, it is disadvantageous in terms of lifespan. To prevent the rollers from coming off, it is conceivable to integrally provide a flange portion having a diameter larger than that of the eccentric portion over the entire circumference on the outer periphery of the crankshaft. However, in this case, since the flange portion is integral with the crankshaft, increasing the outer diameter of the flange portion interferes with the central hole of the external gear and makes assembly difficult.

[0043] Therefore, in the present embodiment, in order to restrict the axial movement of the rollers 34a and 36a, the hollow disk-shaped retaining portions 26, 27, and 28 are arranged on the outer periphery of the crankshaft 12 separately from the crankshaft 12. With this configuration, while maintaining assemblability, it is possible to increase the diameter of the retaining portions 26, 27, and 28, and effectively prevent the rollers 34a and 36a from coming off.

[0044] In the present embodiment, the retaining portions 26, 27, and 28 include a first retaining portion 26 arranged between the first crankshaft bearing 30 and the first roller 34a, a second retaining portion 28 arranged between the second crankshaft bearing 32 and the second roller 36a, and an intermediate retaining portion 27 arranged between the first eccentric body bearing 34 and the second eccentric body bearing 36.

[0045] By having the first retaining portion 26, the movement of the first roller 34a toward the first crankshaft bearing 30 side can be restricted. By having the second retaining portion 28, the movement of the second roller 36a toward the second crankshaft bearing 32 side can be restricted. By having the intermediate retaining portion 27, the mutual interference between the first roller 34a and the second roller 36a can be prevented. As shown in FIG. 1, the intermediate retaining portion 27 abuts on the external gears 14 and 15 when it is located in the anti-eccentric direction and when it is located in the eccentric direction. In this case, the intermediate retaining portion 27 contacts the external gears 14 and 15 regardless of the rocking position of the external gears 14 and 15, and can also restrict the axial movement of the external gears 14 and 15.

[0046] As shown in Fig. 1, in the present embodiment, the outer shapes of the retaining portions 26, 27, and 28 extend radially outside the center lines L34 and L36 of the rollers 34a and 36a located in the eccentric direction. In this case, the rollers 34a and 36a can be more effectively prevented from coming off.

[0047] As shown in Fig. 2, in the present embodiment, the first retaining portion 26 fits into an extension portion on the input side of the first shaft support portion 12c adjacent to the non-input side of the first eccentric portion 12a, and the second retaining portion 28 fits into an extension portion on the non-input side of the shaft support portion 12d adjacent to the input side of the second eccentric portion 12b. The intermediate retaining portion 27 fits into the eccentric region of the first eccentric portion 12a and the eccentric region of the second eccentric portion 12b.

[0048] The operation of the speed reduction device 100 will be described. When rotation is transmitted from the motor to the crankshaft 12, the eccentric portions 12a and 12b of the crankshaft 12 rotate around the rotation center line passing through the crankshaft 12, and the external gear wheels 14 and 15 swing via the eccentric body bearings 34 and 36. When the external gear wheels 14 and 15 swing, the meshing positions of the external gear wheels 14 and 15 and the internal gear wheel 16 shift sequentially. As a result, every time the crankshaft 12 makes one rotation, rotation of one of the external gear wheels 14 and 15 and the internal gear wheel 16 corresponding to the difference in the number of teeth between the external gear wheels 14 and 15 and the internal gear wheel 16 occurs. In the present embodiment, decelerated rotation is output from the first carrier 18 that is synchronized with the rotation of the external gear wheels 14 and 15 via the inner pin 38.

[0049] The features of the speed reduction device 100 configured as described above will be described. Since the speed reduction device 100 has the bent portion 12k in the region recessed in the non-eccentric direction of the eccentric portion, stress concentration on this portion can be alleviated. Also, since the outer shape of the retaining portion can be enlarged, axial movement of the rollers 34a and 36a can be restricted, and leakage of the lubricant of the eccentric portions 12a and 12b to the main bearing 24 side can be suppressed. Further, since the intermediate retaining portion 27 is provided, the sliding partners of the end faces of the rollers 34a and 36a do not change, which is advantageous in terms of life, and leakage of the lubricant of the eccentric portions 12a and 12b from the center holes 14c and 15c of the external gear wheels 14 and 15 can be suppressed.

[0050] Hereinafter, the second to fifth embodiments of the present disclosure will be described. In the drawings and descriptions of the second to fifth embodiments, the same or equivalent components and members as those in the first embodiment are denoted by the same reference numerals. Descriptions overlapping with the first embodiment are omitted as appropriate, and configurations different from the first embodiment will be mainly described. Therefore, the description of the first embodiment is applicable to the same or equivalent components and members as those in the first embodiment in the second to fifth embodiments.

[0051] [Second Embodiment] Referring to FIG. 3, the configuration of the eccentric swing type reduction gear 100 according to the second embodiment of the present disclosure will be described. FIG. 3 is a cross-sectional view showing the overall configuration of the reduction gear 100 according to the present embodiment.

[0052] In the present embodiment, it is different from the first embodiment in that the second retaining portion 28 is integrally formed with the second carrier 20, and a protrusion 12p corresponding to the second retaining portion 28 is provided on the crankshaft 12, and other configurations are common. Therefore, mainly the second retaining portion 28 and the protrusion 12p of the crankshaft 12 will be described.

[0053] In the example of FIG. 3, the second carrier 20 has a carrier main body portion 20b that supports the input side of the inner pin 38, and a hollow disk-shaped extending retaining portion 20c that extends radially inward from the inner peripheral portion of the carrier main body portion 20b. The carrier main body portion 20b and the extending retaining portion 20c are integrally formed. The extending retaining portion 20c has an inner shape that does not overlap with the center line L36 of the roller 36a (the upper roller in the figure) located in the anti-eccentric direction when viewed axially, and overlaps with the center line L36 of the roller 36a (the lower roller in the figure) located in the eccentric direction.

[0054] In the example of FIG. 3, the protrusion 12p is a substantially disk-shaped portion that protrudes radially outward from an extension portion of the second shaft support portion 12d toward the anti-input side at an axial position corresponding to the extending retaining portion 20c. When viewed axially, the protrusion 12p overlaps with the center line L36 of the roller 36a (the upper roller in the figure) located in the anti-eccentric direction and does not overlap with the center line L36 of the roller 36a (the lower roller in the figure) located in the eccentric direction.

[0055] This embodiment exhibits the same operations and effects as the first embodiment.

[0056] [Third Embodiment] Referring to FIG. 4, the configuration of the eccentric swing type reduction gear 100 according to the third embodiment of the present disclosure will be described. FIG. 4 is a cross-sectional view showing the overall configuration of the reduction gear 100 according to this embodiment.

[0057] In this embodiment, it is different from the first embodiment in that protrusions 12q and 12r corresponding to the first retaining portion 26 are provided on the crankshaft 12, and other configurations are common. Therefore, mainly the protrusions 12q and 12r of the crankshaft 12 will be described.

[0058] In the example of FIG. 4, the protrusion 12q is a substantially disc-shaped portion that protrudes radially outward from an extension portion on the input side of the first shaft support portion 12c at an axial position corresponding to the first retaining portion 26. The protrusion 12r is a substantially disc-shaped portion that protrudes radially outward from an extension portion on the non-input side of the second shaft support portion 12d at an axial position corresponding to the second retaining portion 28. The outer shape of the protrusion 12q does not overlap with the center line L34 of the roller 34a located in the eccentric direction when viewed from the axial direction. Also, the inner shape of the first retaining portion 26 overlaps with the outside of the protrusion 12q when viewed from the axial direction. The outer shape of the protrusion 12r does not overlap with the center line L36 of the roller 36a located in the eccentric direction when viewed from the axial direction. Also, the inner shape of the second retaining portion 28 overlaps with the outside of the protrusion 12r when viewed from the axial direction.

[0059] This embodiment exhibits the same operations and effects as the first embodiment.

[0060] [Fourth Embodiment] Referring to FIG. 5, the configuration of the eccentric swing type reduction gear 100 according to the fourth embodiment of the present disclosure will be described. FIG. 5 is a cross-sectional view showing the overall configuration of the reduction gear 100 according to this embodiment.

[0061] In this embodiment, it is different from the first embodiment in that the inside of the first retaining portion 26 has a larger diameter and a protrusion 12s corresponding to the first retaining portion 26 is provided on the crankshaft 12, and other configurations are common. Therefore, mainly the protrusion 12s of the crankshaft 12 will be described.

[0062] In the example of FIG. 5, the protrusion 12s is a substantially disc-shaped portion that protrudes radially outward from an extension portion on the input side of the first shaft support portion 12c at an axial position corresponding to the first retaining portion 26. The outer shape of the protrusion 12s in this embodiment is larger than the outer shape of the protrusion 12q in the first embodiment. Also, the inner shape of the first retaining portion 26 in this embodiment does not overlap with the protrusion 12s when viewed axially. Therefore, the first retaining portion 26 surrounds the outer periphery of the protrusion 12s with a gap therebetween.

[0063] This embodiment exhibits the same operations and effects as the first embodiment.

[0064] As described above, the examples of the embodiments of the present invention have been described in detail. The above-described embodiments are merely specific examples for implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention, and many design changes such as changes, additions, deletions, etc. of components are possible without departing from the idea of the invention defined in the claims. In the above-described embodiments, regarding the content for which such design changes are possible, descriptions are given with notations such as "in the embodiment" and "in the embodiment", but design changes are not necessarily not allowed for the content without such notations. Also, the hatching attached to the cross-section of the drawings does not limit the material of the object to which the hatching is attached.

[0065] Hereinafter, modified examples will be described. In the drawings and descriptions of the modified examples, the same or equivalent components and members as those in the embodiments are denoted by the same reference numerals. Descriptions overlapping with those of the embodiments will be omitted as appropriate, and the configurations different from those of the embodiments will be mainly described.

[0066] [Modified Example] In the description of the embodiment, an example in which the casing 22 is composed of four members is shown, but the casing may be composed of three or fewer or five or more members.

[0067] In the description of the embodiment, an example in which the number of external gears is 2 has been shown. However, the number of external gears may be 1 or 3 or more.

[0068] In addition to the inner pin 38, a carrier pin that does not contribute to the transmission of the driving force may be provided as a pin member for connecting the carriers 18 and 20.

[0069] In the description of the embodiment, an example in which the inner pin 38 is separate from the first carrier 18 has been shown. However, the inner pin 38 may be integrally formed with the first carrier 18.

[0070] In the description of the embodiment, an example in which the inner ring of the main bearing 24 is integrally formed with the carrier 18 and the outer ring of the main bearing 24 is integrally formed with the casing 22 has been shown. However, the inner ring or the outer ring of the main bearing may be separate from the carrier or the casing.

[0071] In the description of the embodiment, an example in which the speed reduction device 100 is a so-called center crank type planetary gear device has been shown. However, the present invention is not limited to this. The present invention can also be applied to, for example, an eccentric swing type speed reduction device such as a distribution type.

[0072] Each of the above-described modification examples has the same operations and effects as the embodiment.

[0073] Any combination of the components of the above-described embodiment and the modification examples is also useful as an embodiment of the present invention. The new embodiment resulting from the combination has the effects of the combined embodiment and modification example.

Description of Reference Numerals

[0074] 12 crankshaft, 12a first eccentric portion, 12b second eccentric portion, 12c first shaft support portion, 12d second shaft support portion, 12k bent portion, 12p protrusion, 12u first opposing surface, 12v second opposing surface, 14 first external gear, 15 second external gear, 18 first carrier, 20 second carrier, 22 casing, 26 first retaining portion, 27 intermediate retaining portion, 28 second retaining portion, 30 first crankshaft bearing, 32 second crankshaft bearing, 34 first eccentric body bearing, 34k curved surface portion, 36 second eccentric body bearing, 34a, 36a roller, 100 eccentric swing type reduction gear device.

Claims

1. A crankshaft having an eccentric portion, a crankshaft bearing for supporting the crankshaft, an eccentric body bearing disposed radially outside the eccentric portion, and comprising: the eccentric body bearing is a spherical roller bearing, the eccentric portion is recessed on the anti-eccentric direction side, the rollers of the eccentric body bearing have an outer diameter at the axially outer end portion smaller than the outer diameter at the axially central portion, the crankshaft has a retaining portion disposed on the outer periphery thereof to restrict axial movement of the roller, the retaining portion includes an outer retaining portion for restricting axial movement of the roller to the outside of the main reduction gear, the outer retaining portion is provided separately from the crankshaft, the crankshaft has a first opposing surface facing the roller and restricting movement of the roller in the same direction as the direction restricted by the outer retaining portion, the outer retaining portion is characterized in that its outer shape extends radially outside the center line of the roller located in the eccentric direction, an eccentric swing type reduction gear.

2. The crankshaft has a curved portion that is connected by a curve from a first opposing surface axially facing the roller to a second opposing surface radially facing the roller in a region of the anti-eccentric direction of the eccentric portion, the eccentric swing type reduction gear according to claim 1.

3. The outer diameter of the axially end portion of the roller is 20% or less of the outer diameter of the axially central portion of the roller, the eccentric swing type reduction gear according to claim 1 or 2.

4. The eccentric body bearing includes a first eccentric body bearing and a second eccentric body bearing disposed axially spaced apart, the retaining portion is disposed between the first eccentric body bearing and the second eccentric body bearing and includes an intermediate retaining portion for restricting axial movement of the first eccentric body bearing and the second eccentric body bearing, the intermediate retaining portion is provided on the outer peripheral surface of the eccentric portion, the eccentric swing type reduction gear according to claim 1 or 2.

5. A crankshaft having an eccentric portion, a crankshaft bearing for supporting the crankshaft, an eccentric body bearing disposed radially outside the eccentric portion, and comprising: the eccentric body bearing is a spherical roller bearing, the eccentric portion is recessed on the anti-eccentric direction side, the rollers of the eccentric body bearing have an outer diameter at the axially outer end portion smaller than the outer diameter at the axially central portion, the crankshaft has a retaining portion disposed on the outer periphery thereof to restrict axial movement of the roller, the retaining portion is provided separately from the crankshaft, the crankshaft has a carrier that oscillates in synchronization with the rotation of an external gear that rotates as the crankshaft rotates. The anti-disengagement portion includes an extending anti-disengagement portion that extends radially inward from the inner peripheral portion of the carrier, and the eccentric swing type reduction gear is characterized by this.

6. The eccentric body bearing includes a first eccentric body bearing and a second eccentric body bearing that are arranged at an axial distance from each other. The anti-disengagement portion is arranged between the first eccentric body bearing and the second eccentric body bearing, and includes an intermediate anti-disengagement portion that restricts the axial movement of the first eccentric body bearing and the second eccentric body bearing. The eccentric swing type reduction gear according to any one of claims 1 to 5, wherein the intermediate anti-disengagement portion is provided separately from the crankshaft.

7. It has an external gear that swings as the crankshaft rotates. The eccentric swing type reduction gear according to claim 6, wherein the intermediate anti-disengagement portion restricts the axial movement of the external gear when it is located in the anti-eccentric direction and when it is located in the eccentric direction.

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