Eccentric oscillating speed reducer

Abstract

To provide an eccentric oscillation type speed reducer that can improve insufficient lubrication of an eccentric part.SOLUTION: An eccentric oscillation type speed reducer 100 comprises an external gear 14, a crankshaft 12 comprising an eccentric part 12f for oscillating the external gear 14, and a plurality of rollers 34a arranged in a circumferential direction between the external gear 14 and the eccentric part 12f. The plurality of rollers 34a can come into contact with one another in the circumferential direction. The eccentric oscillation type speed reducer comprises a groove part 12e in the eccentric part 12f, and comprises a guide structure 5 for guiding a lubricant J moved to the outside from the groove part 12e, to the eccentric part 12f.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A gear device that transmits the eccentric movement of an eccentric part to an external gear via an eccentric bearing is known. For example, Patent Document 1 describes a reduction gear including an eccentric part that is eccentric with respect to an input shaft, an external gear that is rotatably mounted on the eccentric part via a needle bearing, an internal gear that is mounted on the external gear and meshes with the external gear, and a carrier that is disposed so as to sandwich the external gear. This reduction gear reduces the rotation input to the input shaft and outputs it from the carrier or the internal gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The needle bearing of the reduction gear described in Patent Document 1 is a full roller type without a retainer for holding the rollers in a predetermined position, and a restricting wall for restricting the axial movement of the rollers is provided on the input shaft. Further, a circumferential groove (circumferential direction groove) is provided on the input shaft between the restricting wall and the eccentric part. In this configuration, when the eccentric part rotates, the lubricant in the circumferential groove moves to the outer peripheral side due to the centrifugal force generated by the rotation. The lubricant that has moved to the outer peripheral side is difficult to be supplied to the circumferential groove again even when the centrifugal force disappears, and there is a problem that the lubrication of the eccentric part becomes insufficient.

[0005] The present invention has been made in view of such problems, and one object of the present invention is to provide an eccentric swing type reduction gear capable of improving insufficient lubrication of an eccentric part.

Means for Solving the Problems

[0006] To solve the above problems, an eccentric oscillating type speed reducer according to one aspect of the present invention comprises an external gear, a crankshaft having an eccentric portion that oscillates the external gear, and a plurality of rollers arranged circumferentially between the external gear and the eccentric portion. The plurality of rollers are capable of contacting each other circumferentially, and the eccentric oscillating type speed reducer has a groove portion in the eccentric portion, and has a guide structure that guides lubricant that has moved outward from the groove portion to the eccentric portion.

[0007] Furthermore, any combination of the above components, or in which the components or expressions of the present invention are mutually substituted among methods, systems, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an eccentric oscillating type speed reducer that can improve the lack of lubrication in the eccentric portion. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side cross-sectional view showing an eccentric oscillating type speed reducer according to an embodiment. [Figure 2] This is a side cross-sectional view showing the periphery of the guide structure in Figure 1. [Figure 3] This figure shows a first example of the guidance structure shown in Figure 1. [Figure 4] This is a side cross-sectional view showing a second example of the guide structure in Figure 1. [Figure 5] This is a side cross-sectional view showing a third example of the guide structure in Figure 1. [Modes for carrying out the invention]

[0010] The present invention will be described below with reference to the drawings, based on preferred embodiments. In embodiments and modifications, the same or equivalent components and members will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding. Furthermore, some members that are not important for explaining the embodiments will be omitted from the drawings.

[0011] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves.

[0012] [Embodiment] The configuration of the eccentric oscillating type reducer 100 (hereinafter sometimes simply referred to as "reducer 100") according to the embodiment of this disclosure will be described below with reference to the drawings. Figure 1 is a schematic side cross-sectional view showing the reducer 100. There are no limitations on the application of the reducer 100, and the reducer 100 in this example can be used for a variety of applications, such as robots.

[0013] The gearbox 100 has a guide structure 5 that guides the lubricant J that has escaped outward from the grooves 12e, 12g, 12j, and 12m of the crankshaft 12 due to centrifugal force to the eccentric parts 12f and 12k. The guide structure 5 will be described in detail later. First, the overall configuration of the gearbox 100 will be explained. There are no limitations to the configuration of the gearbox 100, but the gearbox 100 in this example is a center-crank type planetary gear system in which the rotation of the crankshaft 12 causes the external gears 14 and 15 to oscillate via eccentric bearings 34 and 36, and the rotation of the external gears 14 and 15 is transmitted to the carriers 18 and 20 via an internal pin 38. The gear reducer 100 mainly comprises a crankshaft 12, external gears 14 and 15, internal gear 16, carriers 18 and 20, casing 22, main bearing 24, crankshaft bearings 30 and 32, eccentric bearings 34 and 36, and an internal pin 38.

[0014] Hereinafter, the direction along the central axis La of the internal gear 16 will be referred to as the "axial direction," and the circumferential and radial directions of the circle centered on that central axis La will be referred to as the "circumferential direction" and "radial direction," respectively. Also, for convenience, one side of the axial direction (right side in the diagram) will be referred to as the input side, and the other side (left side in the diagram) will be referred to as the non-input side. This notation of directions does not restrict the operating position of the reducer 100, and the reducer 100 can be used in any position.

[0015] The crankshaft 12 has a hollow cylindrical shape with a hollow portion H at its center. For example, a motor shaft is connected to the input end of the crankshaft 12. The crankshaft 12 has two eccentric portions 12f and 12k that are 180° apart in phase. The eccentric portions 12f and 12k include a first eccentric portion 12f and a second eccentric portion 12k provided on the input side of the first eccentric portion 12f. The number of eccentric portions is not limited to two, and may be one or three or more.

[0016] The crankshaft 12 is supported by the carriers 18, 20 and the casing 22 via crankshaft bearings 30, 32. The crankshaft 12 has shaft supports 12c, 12p which are supported by the crankshaft bearings 30, 32. The first shaft support 12c is fitted with the first crankshaft bearing 30, which will be described later, and the second shaft support 12p is fitted with the second crankshaft bearing 32.

[0017] The crankshaft bearings 30 and 32 include a first crankshaft bearing 30 located on the non-input side of the external gears 14 and 15, and a second crankshaft bearing 32 located on the input side of the external gears 14 and 15. There are no restrictions on the configuration of the crankshaft bearings 30 and 32, but in this example, the crankshaft bearings 30 and 32 are deep groove ball bearings.

[0018] The eccentric bearings 34 and 36 are positioned between the eccentric portions 12f and 12k and the external gears 14 and 15. The eccentric bearings 34 and 36 include a first eccentric bearing 34 positioned on the outer circumference of the first eccentric portion 12f and a second eccentric bearing 36 positioned on the outer circumference of the second eccentric portion 12k. The eccentric bearings 34 and 36 are full-roller bearings having multiple rollers 34a and 36a as rolling elements. Here, a full-roller bearing is a bearing that does not have a cage (retainer) that restricts circumferential contact between adjacent rollers in the circumferential direction (restricts the circumferential position of each roller).

[0019] The external gears 14 and 15 include a first external gear 14 positioned on the outer circumference of a first eccentric bearing 34 and a second external gear 15 positioned on the outer circumference of a second eccentric bearing 36. The carriers 18 and 20 include a first carrier 18 positioned on the non-input side of the external gears 14 and 15 and a second carrier 20 positioned on the input side of the external gears 14 and 15.

[0020] The external gear wheels 14 and 15 are rotatably supported by corresponding eccentric portions 12f and 12k via eccentric bearings 34 and 36. The external gear wheels 14 and 15 are provided with central holes 14c and 15c that are provided at the centers of the external gear wheels 14 and 15 and penetrate in the axial direction. The external gear wheels 14 and 15 are provided at positions offset from the centers of the external gear wheels 14 and 15 and have a plurality of inner pin holes 14h and 15h that penetrate in the axial direction. In the example of FIG. 1, six 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.

[0021] The internal gear wheel 16 meshes with the external gear wheels 14 and 15. The internal gear wheel 16 of the present embodiment is composed of an internal gear wheel main body 16b integrated on the inner circumferential side of the casing 22 and an external pin 16a (pin member) rotatably supported by 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 1 in this example) more than the number of external teeth of the external gear wheels 14 and 15.

[0022] The first carrier 18 supports the anti-input side of the crankshaft 12 via the first crankshaft bearing 30. The first carrier 18 has a radially central hole 18h that supports the first crankshaft bearing 30 and a plurality of through holes 18p provided at predetermined intervals (for example, 60°) in the circumferential direction at positions offset radially from the central axis La.

[0023] The second carrier 20 supports the input side of the crankshaft 12 via the second crankshaft bearing 32. The second carrier 20 has a radially central hole​​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), while the other functions as a fixed member that is fixed to an external member for supporting the reduction gear 100. In this embodiment, the output member is the first carrier 18, and the fixed member is the casing 22. The driven device (not shown) is connected to the end face of the first carrier 18 on the side opposite to the input.

[0025] Multiple internal pins 38 are arranged at predetermined intervals (e.g., 60°) in the circumferential direction. Figure 1 shows one internal pin 38. The internal pin 38 penetrates the internal pin holes 14h and 15h axially at a position radially offset from the central axis La. The internal pin 38 connects the first carrier 18 and the second carrier 20 by fitting into the through holes 18p and 20p.

[0026] A sleeve 38s is rotatably fitted to the outer circumference of the inner pin 38. The sleeve 38s is inserted through the inner pin holes 14h and 15h with a gap between them. The inner pin 38 contacts a portion of the inner pin holes 14h and 15h via the sleeve 38s. The inner pin 38 restricts the rotation of the external gears 14 and 15, allowing only their oscillation. With this configuration, the carriers 18 and 20 move in sync with the rotation of the external gears 14 and 15 via the inner pin 38.

[0027] The casing 22 is a hollow cylindrical member that constitutes the outer shell of the reducer 100. The casing 22 includes a first casing 22a, a second casing 22b, a third casing 22c, and a fourth casing 22d, which are stacked in this order from the non-input side toward the input side. The fourth casing 22d has a bearing support hole 22h in its radial center.

[0028] The first casing 22a and the second casing 22b mainly surround the first carrier 18. The third casing 22c mainly surrounds the external gears 14 and 15. An internal gear 16 is provided on the inner circumferential surface of the third casing 22c. The fourth casing 22d mainly covers the outer circumferential surface and input side surface of the second carrier 20. The bearing support hole 22h of the fourth casing 22d supports the second crankshaft bearing 32. The first casing 22a, the second casing 22b, the third casing 22c, and the fourth casing 22d are integrated by predetermined connecting means.

[0029] The main bearing 24 is positioned between the first carrier 18 and the casing 22. While there are no restrictions on the configuration of the main bearing 24, in this example, it is a cross-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 first carrier 18. The main bearing 24 rotatably supports the first carrier 18 relative to the casing 22.

[0030] The operation of the reduction gear 100 will now be explained. When rotation is transmitted to the crankshaft 12, the eccentric portions 12f and 12k of the crankshaft 12 rotate around the rotational center line passing through the crankshaft 12, causing the external gears 14 and 15 to oscillate via the eccentric bearings 34 and 36. As the external gears 14 and 15 oscillate, the meshing positions of the external gears 14 and 15 and the internal gear 16 shift sequentially. As a result, with each rotation of the crankshaft 12, a rotation occurs in either the external gears 14 and 15 or the internal gear 16 by an amount equivalent to the difference in the number of teeth between the external gears 14 and 15 and the internal gear 16. In this embodiment, a reduction rotation is output from the first carrier 18, which is synchronized with the rotation of the external gears 14 and 15, via the internal pin 38.

[0031] The guide structure 5 of this disclosure will be described with reference to Figures 1, 2, and 3. Figure 2 is a side cross-sectional view showing the periphery of the guide structure 5. Between the first shaft support 12c and the second shaft support 12p, the crankshaft 12 is provided with a first wall portion 12d, a first groove portion 12e, a first eccentric portion 12f, a second groove portion 12g, a second wall portion 12h, a third groove portion 12j, a second eccentric portion 12k, a fourth groove portion 12m, and a third wall portion 12n in the axial direction, from the anti-input side to the input side. As an example, the groove portions 12e, 12g, 12j, and 12m of the embodiment are circumferential grooves.

[0032] The walls 12d, 12h, and 12n of this embodiment are circumferential walls provided around the crankshaft 12 in the circumferential direction. The walls 12d, 12h, and 12n extend radially and overlap with a portion of the sides of the rollers 34a and 36a, restricting the axial movement of the rollers 34a and 36a. For example, the walls 12d, 12h, and 12n are provided coaxially with the central axis La. The first wall 12d is located between the first crankshaft bearing 30 and the first roller 34a, restricting the movement of the first roller 34a toward the input side. The second groove 12g is located between the first roller 34a and the second roller 36a. The third wall 12n is located between the second roller 36a and the second crankshaft bearing 32, restricting the movement of the second roller 36a toward the non-input side.

[0033] The grooves 12e, 12g, 12j, and 12m are circumferential grooves that are recessed radially and are provided around the crankshaft 12 in the circumferential direction. For example, the grooves 12e, 12g, 12j, and 12m are provided coaxially with the central axis La. The grooves 12e and 12g are provided on both sides of the first eccentric portion 12f, sandwiching it in the axial direction. In other words, the first groove 12e is provided between the first wall portion 12d and the first eccentric portion 12f, and the second groove 12g is provided between the first eccentric portion 12f and the second wall portion 12h. A first arrangement portion 33, which is an annular space in which the first roller 34a is arranged, is formed on the outer circumference side of the grooves 12e, 12g and the first eccentric portion 12f.

[0034] The grooves 12j and 12m are provided on both sides of the second eccentric portion 12k, sandwiching it in the axial direction. In other words, the third groove 12j is provided between the second wall portion 12h and the second eccentric portion 12k, and the fourth groove 12m is provided between the second eccentric portion 12k and the third wall portion 12n. A second arrangement portion 35, which is an annular space in which the second roller 36a is arranged, is formed on the outer circumference of the grooves 12j and 12m and the second eccentric portion 12k.

[0035] Thus, when the crankshaft 12 has grooves 12e, 12g, 12j, and 12m, the lubricant J in the eccentric portions 12f and 12k moves outward along the grooves when centrifugal force acts. Even after the centrifugal force is removed, the lubricant that has moved outward does not easily return to its original area in the eccentric portions 12f and 12k, which may result in insufficient lubrication between the eccentric portions 12f and 12k and the rollers 34a and 36a. Therefore, the reducer 100 of this embodiment has a guide structure 5 that guides the lubricant J that has moved outward from the grooves 12e, 12g, 12j, and 12m of the crankshaft 12 due to centrifugal force to the eccentric portions 12f and 12k.

[0036] (Example 1) A first example of the guide structure 5 will be described with reference to Figures 2 and 3. Figure 3 is a diagram showing the first example of the guide structure 5. In the first example, the guide structure 5 includes guide grooves 51, 52, 53, and 54 that extend radially with opposing surfaces 12q, 12r, 12s, and 12t that face the axially opposite rollers 34a and 36a of the wall portions 12d, 12h, and 12n that form the groove portions 12e, 12g, 12j, and 12m. Below, the guide groove 51 of the first wall portion 12d will be mainly described, but the description of guide groove 51 can also be applied to the other guide grooves 52, 53, and 54. Figure 3 is a view of the first wall portion 12d from the input side, showing the guide groove 51. Multiple guide grooves 51 are arranged at predetermined intervals in the circumferential direction (for example, 24).

[0037] The guide groove 51 is recessed in the opposite direction from the opposing surface 12q to the roller 34a. By providing the guide groove 51, it is expected that the lubricant J that has moved outward will be drawn towards the eccentric portion 12f by capillary action.

[0038] The guide groove may be constant, but as shown in Figure 3, the guide groove 51 in this embodiment has a wider width as it extends radially outward. In this case, because the guide groove 51 is wider radially, it is easier to collect the lubricant J that falls from the radially outward side when the centrifugal force is removed. The outermost width W1 (maximum width) of the guide groove 51 is greater than the innermost width W2 (minimum width). In this case, it is expected that the lubricant J from the wider outer region of the guide groove 51 will be drawn to the narrower inner region by capillary action and supplied to the eccentric portion 12f.

[0039] From the viewpoint of not impairing the movement restriction function of the wall portion 12d for the roller 34a, the maximum width W1 of the guide groove 51 is set to be smaller than the width of the area 34s of the roller 34a that faces the guide groove 51. In this case, the possibility of the roller 34a entering the guide groove 51 can be reduced.

[0040] (Second example) A second example of the guide structure 5 will be described with reference to Figure 4. Figure 4 is a diagram showing the second example of the guide structure 5. It is desirable that the guide structure 5 be able to smoothly guide the lubricant J that has moved outward to the eccentric portions 12f and 12k. Therefore, in the second example, as shown in Figure 4, the guide structure 5 includes inner diameter enlargement portions 14d and 15d whose inner diameter is enlarged axially outward from the arrangement portions 33 and 35 where the rollers 34a and 36a of the external gears 14 and 15 are arranged. The inner diameter enlargement portions 14d and 15d are provided radially inward from a plurality of through holes (internal pin holes 14h and 15h) provided in the external gears 14 and 15 at positions offset from the centers of the external gears 14 and 15. In particular, in the embodiment, the enlarged inner diameter portions 14d and 15d are provided radially inward from the inscribed circles of a plurality of through holes (internal pin holes 14h and 15h) provided in the external gears 14 and 15 at positions offset from the centers of the external gears 14 and 15. The enlarged inner diameter portions 14d and 15d may also be provided radially inward from the outer diameter of the first crankshaft bearing 30. The enlarged inner diameter portions 14d and 14e are formed on the non-input side and input side of the external gear 14. The enlarged inner diameter portions 15d and 15e are formed on the non-input side and input side of the external gear 15. As an example, the external gear 14 may have an enlarged inner diameter portion 14d in the portion that radially overlaps with the guide groove 51.

[0041] The region sandwiched between the enlarged inner diameter portions 14d and 14e of the external gear 14 in the axial direction is a width reduction region 14f, in which the axial width is smaller than that of the region 14g further outward. The axial width of the width reduction region 14f may be approximately the same as the axial width of the roller 34a. The region sandwiched between the enlarged inner diameter portions 15d and 15e of the external gear 15 in the axial direction is a width reduction region 15f, in which the axial width is smaller than that of the region 15g further outward. The axial width of the width reduction region 15f may be approximately the same as the axial width of the roller 36a.

[0042] The following description will mainly focus on the internal diameter enlargement portion 14d of the external gear 14, but the description of the internal diameter enlargement portion 14d can also be applied to the other internal diameter enlargement portion 15d.

[0043] The inner diameter enlargement portion 14d is formed in a stepped shape. When the inner diameter enlargement portion 14d is present, the axial clearance between the external gear 14 and its opposing member (first crankshaft bearing 30) is larger compared to when the inner diameter enlargement portion 14d is not present, and the resistance to the movement of the lubricant J is reduced. As a result, the lubricant J that has moved outward can be easily moved to the inner circumference, and the lubricant J can be smoothly guided to the eccentric portions 12f and 12k. In addition, the lubricant J that moves outward due to centrifugal force can be retained on the outer stepped portion of the inner diameter enlargement portion 14d, and when the centrifugal force is removed, the lubricant J retained on the stepped portion can be supplied to the inner circumference. The outer stepped portion of the inner diameter enlargement portion 14d faces the guide groove 51 in the radial direction.

[0044] (Third example) A third example of the guide structure 5 will be described with reference to Figure 5. Figure 5 is a diagram showing the third example of the guide structure 5. It is desirable that the lubricant J that has moved outward be efficiently guided toward the eccentric portion 12f. Therefore, in the third example, a projection 60 is provided on the outer circumference of a specific wall portion 12d, which is the outermost wall portion 12d in the axial direction among the wall portions 12d, 12h, and 12n, projecting radially from the outer circumference. The guide structure 5 includes an outer diameter reduction portion 62, the outer diameter of which decreases as it approaches the roller 34a of the projection portion 60. In this case, when the centrifugal force is eliminated, the lubricant J on the outer circumference is guided toward the roller 34a by the outer diameter reduction portion 62, so that the lubricant J is efficiently guided toward the eccentric portion 12f. In this example, the outer diameter of the outer diameter reduction portion 62 gradually decreases toward the center of the external gear 14.

[0045] In the example shown in Figure 5, the protrusion 60 is provided on a partition plate 6, which is an annular member. The partition plate 6 can be formed, for example, from a sheet material by press molding. The partition plate 6 has, in order from the inner circumference, a disc-shaped radially extending portion 63, a cylindrical axially extending portion 64, a conical cylindrical outer diameter reduction portion 62, and a disc-shaped radially extending portion 65. In this case, since the protrusion 60 is formed separately from the specific wall portion 12d, the desired shape can be easily realized. Also, the protrusion 60 can be made thin. In the example shown in Figure 5, a protrusion 60 is also provided on the outer circumference of the wall portion 12n. The protrusion 60 of the wall portion 12n has the same configuration as the protrusion 60 of the wall portion 12d described above and performs the same function. A redundant explanation of this configuration will be omitted.

[0046] Figure 5 shows an example where the partition plate 6 is an independent component, but the design is not limited to this. For example, the protrusion 60 may be integrated with the oil seal of the bearing (first crankshaft bearing 30) provided on the side of the specific wall portion 12d. In this case, ease of assembly is improved, and interference between the protrusion 60 and the external gear 14 can be reduced.

[0047] It is desirable to guide the lubricant J to the eccentric portion 12f more efficiently. Therefore, in the third example, the external gear 14 has a width reduction portion 14j in the portion that overlaps radially with the outer diameter reduction portion 62, where the axial width decreases as it approaches the center of the external gear 14. In this case, when the centrifugal force is eliminated, the lubricant J on the outer circumference moves along the width reduction portion 14j toward the roller 34a, so that the lubricant J is efficiently guided to the eccentric portion 12f. In this example, the axial width of the width reduction portion 14j gradually decreases toward the center of the external gear 14. In particular, in this embodiment, the width reduction portion 14j is located axially outward from the arrangement portion 33 where the rollers 34a of the external gear 14 are arranged, and radially inward from the inscribed circles of the multiple through holes provided in the external gear 14 at a position offset from the center of the external gear 14, and has a larger inner diameter than the arrangement portion 33. In the example of Figure 5, the external gear 15 has a width reduction portion 15j. The width reduction section 15j has the same configuration as the width reduction section 14j and performs the same function. A redundant explanation of this configuration will be omitted.

[0048] The features of the eccentric oscillating type reducer 100 according to the embodiment will now be described. The eccentric oscillating type reducer 100 includes an external gear 14, a crankshaft 12 having an eccentric portion 12f that oscillates the external gear 14, and a plurality of rollers 34a arranged circumferentially between the external gear 14 and the eccentric portion 12f. The plurality of rollers 34a are capable of contacting each other circumferentially, and the eccentric oscillating type reducer has a groove portion 12e in the eccentric portion 12f, and a guide structure 5 that guides lubricant J that has moved outward from the groove portion 12e to the eccentric portion 12f.

[0049] With this configuration, the lubricant J that has moved outward from the groove 12e due to centrifugal force is guided to the eccentric portion 12f by the guide structure 5, making it easier for the lubricant J to return to the eccentric portion 12f. As a result, the lack of lubrication in the eccentric portion 12f can be improved.

[0050] The embodiments of the present invention have been described in detail above. The embodiments described above are merely examples of how to implement the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not depart from the spirit of the invention as defined in the claims. In the embodiments described above, such design changes are described with notations such as "of the embodiment" or "in the embodiment," but design changes are also permitted for contents without such notations. Furthermore, the hatching applied to the cross-section in the drawings does not limit the material to which the hatching is applied.

[0051] The following describes modified examples. In the drawings and descriptions of modified examples, components and parts that are the same as or equivalent to those in the embodiments are denoted by the same reference numerals. Descriptions that overlap with those in the embodiments will be omitted as appropriate, and the descriptions will focus on the configurations that differ from those in the embodiments.

[0052] [Differentiation] In the description of the embodiment, an example was shown in which the grooves 12e, 12g, 12j, and 12m are formed circumferentially, but the embodiment is not limited to this. The grooves 12e, 12g, 12j, and 12m may be discontinuous recesses, such as dimples. In this case, the walls 12d, 12h, and 12n may be discontinuous walls.

[0053] In the description of the embodiment, an example was shown where the width of the guide groove 51 increases as the width viewed from the axial direction (circumferential width) increases towards the radially outward direction, but this is not limited to this. The width of the guide groove 51 may be such that the width in the axial direction (groove depth) increases towards the radially outward direction, or both the circumferential width and groove depth may increase towards the radially outward direction. In this case, the lubricant J that falls from the radially outward direction can be recovered more easily.

[0054] Although an example has been shown where the reduction gear 100 is a so-called center-crank type planetary gear system, the present invention is not limited to this. The present invention can also be applied to eccentric oscillating reduction gears such as the distribution type.

[0055] In the description of the embodiment, an example was shown in which the number of external gears is 2, but the number of external gears may be 1 or 3 or more.

[0056] In addition to the inner pin 38, carrier pins that do not contribute to the transmission of driving force may be provided as pin members for connecting carriers 18 and 20.

[0057] In the description of the embodiment, an example was shown in which the inner pin 38 is separate from the first carrier 18, but the inner pin 38 may be formed integrally with the first carrier 18.

[0058] In the description of the embodiment, an example was shown in which the inner ring of the main bearing 24 is formed integrally with the carrier 18 and the outer ring of the main bearing 24 is formed integrally with the casing 22. However, the inner ring of the main bearing may be separate from the carrier, and the outer ring may be separate from the casing.

[0059] In the description of the embodiment, an example was shown in which the casing 22 is composed of four members, but the casing may be composed of three or fewer members, or five or more members.

[0060] Each of the above-described modifications produces the same functions and effects as the embodiments.

[0061] Any combination of the components and modifications of the embodiments described above is also useful as an embodiment of the present invention. The new embodiments resulting from these combinations possess the combined effects of both the combined embodiments and the modifications. [Explanation of Symbols]

[0062] 5 Guide structure, 12 Crankshaft, 12d, 12h, 12n Wall section, 12f, 12k Eccentric section, 12e, 12g, 12j, 12m Groove section, 14, 15 External gear, 14d, 15d Enlarged inner diameter section, 14j, 15j Reduced width section, 34a, 36a Roller, 51, 52, 53, 54 Guide groove, 60 Protrusion, 62 Reduced outer diameter section, 100 Eccentric oscillating type reducer.

Claims

1. It comprises an external gear, a crankshaft having an eccentric portion that causes the external gear to oscillate, and a plurality of rollers arranged circumferentially between the external gear and the eccentric portion, The aforementioned multiple rollers can contact each other in the circumferential direction, The eccentric oscillating type reduction gear has a groove in the eccentric portion, It has a guide structure that guides the lubricant that has moved outward from the groove to the eccentric portion, The guide structure includes a radially extending guide groove formed on the opposing surface side of the wall portion forming the groove, which faces the roller in the axial direction, and is an eccentric oscillating type speed reducer.

2. The eccentric oscillating type reducer according to claim 1, wherein the guide groove has a width that increases towards the radially outward direction.

3. A gear comprising an external gear, a crankshaft having an eccentric portion for oscillating the external gear, and a plurality of rollers arranged circumferentially between the external gear and the eccentric portion, The aforementioned multiple rollers can contact each other in the circumferential direction, The eccentric oscillating type reduction gear has a groove in the eccentric portion, It has a guide structure that guides the lubricant that has moved outward from the groove to the eccentric portion, The guide structure includes an enlarged inner diameter portion, which has a larger inner diameter than the arrangement portion, located axially outward from the arrangement portion where the rollers of the external gear are arranged, and radially inward from a plurality of through holes provided in the external gear at a position offset from the center of the external gear. This is an eccentric oscillating type speed reducer.

4. A gear comprising an external gear, a crankshaft having an eccentric portion for oscillating the external gear, and a plurality of rollers arranged circumferentially between the external gear and the eccentric portion, The aforementioned multiple rollers can contact each other in the circumferential direction, The eccentric oscillating type reduction gear has a groove in the eccentric portion, It has a guide structure that guides the lubricant that has moved outward from the groove to the eccentric portion, A projection is provided on the outer circumference of a specific wall portion that is the outermost wall portion in the axial direction among the wall portions forming the groove portion, projecting radially from the outer circumference. The protruding portion has an outer diameter reduction portion in which the outer diameter decreases as it is directed axially toward the roller side, The guide structure is an eccentric oscillating type reducer, including the outer diameter reduction portion.

5. The guide structure includes an enlarged inner diameter portion, which has a larger inner diameter than the arrangement portion, located axially outward from the arrangement portion where the rollers of the external gear are arranged, and radially inward from the inscribed circles of a plurality of through holes provided in the external gear at a position offset from the center of the external gear. The eccentric oscillating type reducer according to claim 4, wherein the external gear has the internal diameter enlargement portion in a portion that overlaps radially with the external diameter reduction portion.

6. The guide structure includes an enlarged inner diameter portion, which has a larger inner diameter than the arrangement portion, located axially outward from the arrangement portion where the rollers of the external gear are arranged, and radially inward from the inscribed circles of a plurality of through holes provided in the external gear at a position offset from the center of the external gear. The aforementioned specific wall portion has a guide groove extending radially on the opposing surface side that faces the roller in the axial direction, The eccentric oscillating type reducer according to claim 4, wherein the external gear has the enlarged inner diameter portion in the portion that overlaps radially with the guide groove.

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