speed reduction device

Abstract

To provide a reduction gear that can properly inject lubricant into the carrier. [Solution] The reduction gear 1 of the embodiment comprises a case, a carrier 3 rotatably supported by the case, a crankshaft 4 rotatably supported by the carrier 3 via a first crank bearing 7A, and an external gear 5A rotatably supported by the crankshaft 4. The carrier 3 has a first crank insertion hole 42 into which the first crank bearing 7A fits, a ring storage recess 46 formed coaxially with the first crank insertion hole 42 and communicating with the first crank insertion hole 42, and a through hole 45 that allows the bottom surface 46a of the ring storage recess 46 to connect to the outside of the carrier 3. A distance ring 80 is provided housed in the ring storage recess 46, and the distance ring 80 has a passage 95 that allows it to pass between its inner end surface 82c and the through hole 45.

Description

Technical Field

[0001] The present invention relates to a reduction gear. Background Art

[0002] Conventionally, a so-called eccentric oscillating type reduction gear has been known as a reduction gear. This reduction gear includes a cylindrical case (casing) having an internal gear, a carrier rotatably supported by the case, a plurality of crankshafts rotatably supported by the carrier, and external gears accommodated in the carrier and rotatably supported by the plurality of crankshafts.

[0003] The carrier is formed with an accommodation space for accommodating the external gears, and is also formed with crank insertion holes. A bearing is provided in each of the crank insertion holes. Each of the crankshafts is inserted into the corresponding crank insertion hole, and is rotatably supported by the carrier via the bearing. In order to restrict the axial movement of the crankshaft and perform axial positioning of the crankshaft, an annular restriction member is provided in the crank insertion hole in addition to the bearing. The restriction member abuts against the stepped surface of the crankshaft from the axially outer side, so that the axial movement of the crankshaft is restricted and the axial positioning of the crankshaft is performed (for example, see Patent Document 1).

[0004] Incidentally, in order to improve the drive efficiency of the reduction gear as described above, a lubricant is enclosed in the crank insertion holes and the accommodation space. The enclosing of the lubricant is performed, for example, by injecting the lubricant into the inside of the carrier through the crank insertion holes. Prior Art Documents Patent Documents

[0005] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2024-93475 Summary of Invention [Problems that the invention aims to solve]

[0006] In the conventional technology described above, when a restricting member is used to restrict the axial movement and position the crankshaft, the gap between the carrier and the restricting member, and the gap between the crankshaft and the restricting member, almost disappears when the restricting member and the stepped surface of the crankshaft come into contact. As a result, the axial ends of the crankshaft hole are almost completely sealed by the restricting member. In this state, if lubricant is to be injected into the carrier through the crank insertion hole, the internal pressure of the carrier increases, making it impossible to properly inject the lubricant.

[0007] The present invention provides a speed reducer that can properly inject lubricant into the interior of the carrier. [Means for solving the problem]

[0008] A reduction gear according to one aspect of the present invention comprises a cylindrical case having an internal gear, a carrier disposed radially inside the case and rotatably supported by the case, at least one crankshaft rotatably supported by the carrier via a bearing and to which an external rotational force is input, and an external gear housed in the carrier and rotatably supported by the crankshaft and meshing with the internal gear, wherein the carrier has a crank insertion hole into which the bearing fits, a ring storage recess formed coaxially with the crank insertion hole and communicating with the crank insertion hole, and a through hole that allows the bottom surface of the recess of the ring storage recess to connect to the outside of the carrier, and a distance ring housed in the ring storage recess for axial positioning on the crankshaft, the distance ring having a passage that connects the shaft-side end face on the crankshaft side and the through hole.

[0009] This configuration allows lubricant to pass through the distance ring's passages to the inside and outside of the carrier. Therefore, even when lubricant is injected through the crank insertion hole, air can be vented to the outside of the carrier through the passages, preventing an increase in the carrier's internal pressure. Thus, lubricant can be injected into the carrier properly.

[0010] In the above configuration, the passage includes a first groove formed on the outer circumferential surface of the distance ring and a second groove formed on the recess-side end face of the distance ring on the bottom surface side of the recess.

[0011] In the above configuration, at least a portion of the corner of the first groove and at least a portion of the corner of the second groove are chamfered so that their cross-section is arc-shaped.

[0012] In the above configuration, the ring housing recess has a small-diameter recess formed on the bottom surface side of the recess and a large-diameter recess formed on the crank insertion hole side of the small-diameter recess, the diameter of the large-diameter recess is larger than the diameter of the small-diameter recess, the distance ring has a cylindrical portion that fits into the small-diameter recess and a flange portion formed on the crank insertion hole side of the cylindrical portion and housed in the large-diameter recess, the flange portion protrudes radially outward from the cylindrical portion, and the passage includes a first groove formed on the outer circumferential surface of the flange portion and a second groove formed on the outer circumferential surface of the cylindrical portion and on the recess-side end face of the cylindrical portion on the bottom surface side of the recess.

[0013] In the above configuration, the width between the two inner surfaces of the first groove and the second groove that are opposite each other in the circumferential direction gradually increases as it moves away from the first groove bottom surface of the first groove and the second groove bottom surface of the second groove.

[0014] In the above configuration, at least the corner of the first groove on the crank insertion hole side is formed to be recessed from the shaft-side end face of the distance ring, and at least the corner of the second groove on the outer circumferential surface side of the cylindrical portion is formed to be chamfered.

[0015] In the above configuration, the distance ring is formed in a porous shape. [Effects of the Invention]

[0016] The above speed reduction device can properly perform injection of lubricant into the interior of the carrier. [Brief Description of the Drawings]

[0017] [Figure 1] This is a cross-sectional view of the speed reduction device in the embodiment of the present invention. [Figure 2] This is an enlarged view of part II in Figure 1. [Figure 3] This is a perspective view of the distance ring in the embodiment of the present invention as viewed from the axially outer side. [Figure 4] This is a plan view of the distance ring in the embodiment of the present invention as viewed from the axially outer side. [Figure 5] This is a perspective view of the distance ring in the embodiment of the present invention as viewed from the axially inner side. [Modes for Carrying Out the Invention]

[0018] Next, embodiments of the present invention will be described based on the drawings.

[0019] <Speed Reduction Device> Figure 1 is a cross-sectional view of the speed reduction device 1. Figure 1 illustrates only half (the lower half in Figure 1) of the speed reduction device 1 centered on the carrier rotation axis A1 of the carrier 3 constituting the speed reduction device 1. Figure 2 is an enlarged view of part II in Figure 1. As shown in Figure 1 and Figure 2, the speed reduction device 1 includes a cylindrical case 2, a carrier 3 rotatably supported by the case 2 via two main bearings 6, and a speed reduction unit 10 provided on the carrier 3. As the main bearings 6, for example, tapered roller bearings are used.

[0020] In the following description, a direction parallel to the carrier rotation axis A1 is referred to as the axial direction. The rotation direction of the carrier 3 is referred to as the circumferential direction. The radial direction of the carrier 3 orthogonal to the axial direction and the circumferential direction is simply referred to as the radial direction. The term "axially inner side" used in the following description means the axial center side in the case 2, and "axially outer side" means the side opposite to the axial center in the case 2.

[0021] <Case> The central axis of the case 2 coincides with the carrier rotation axis A1. An internal tooth portion 21 is formed at an axially intermediate portion of the inner peripheral surface of the case 2. The "axially intermediate portion" includes not only the center between both axial ends but also the vicinity of the center. A plurality of pin grooves 21a are formed in the internal tooth portion 21. Each pin groove 21a extends in the axial direction and is formed at equal intervals in the circumferential direction. A cylindrical internal tooth pin 25 is disposed in each of the plurality of pin grooves 21a. The internal tooth pins 25 function as internal teeth constituting a part of the speed reduction portion 10.

[0022] On the inner peripheral surface of the case 2, on both sides of the internal tooth portion 21, a first outer ring holding surface 22 and a second outer ring holding surface 23 are formed via stepped surfaces 26 and 27, respectively. The outer ring 61 of the corresponding main bearing 6 is fitted to each outer ring holding surface 22. Each outer ring 61 is axially positioned by abutting against the corresponding stepped surfaces 26 and 27. On the inner peripheral surface of the case 2, on the side opposite to the internal tooth portion 21 across the first outer ring holding surface 22, a seal surface 24 is formed via a stepped surface 28. The inner diameter of the seal surface 24 is larger than the inner diameter of the first outer ring holding surface 22. An oil seal 11 is fitted to the seal surface 24. The oil seal 11 seals between the case 2 and the carrier 3.

[0023] <Carrier> The carrier 3 is composed of a base plate portion 30 and an end plate portion 50 so as to be splittable in the axial direction. The base plate portion 30 is disposed on the first outer ring holding surface 22 side of the case 2. The base plate portion 30 includes a disc-shaped base portion 31 and a plurality of unillustrated support columns protruding from the base portion 31 toward the end plate portion 50. Of the outer circumferential surface of the base portion 31, the axially outer side (opposite to the end plate portion 50) is configured as a sealing surface 34. An oil seal 11 is fitted onto the sealing surface 34. This seals the space between the case 2 and the carrier 3.

[0024] A first inner ring retaining surface 33 is formed axially inward from the sealing surface 34 of the base portion 31 via a stepped surface 35. The outer diameter of the first inner ring retaining surface 33 is smaller than that of the sealing surface 34. The inner ring 62 of the main bearing 6 is fitted onto the first inner ring retaining surface 33. This allows the base portion 30 to rotatably support the case 2. The inner ring 62 is positioned axially by abutting against the stepped surface 35.

[0025] Multiple (three in this embodiment) first mounting holes 41 are formed radially inward from the first inner ring retaining surface 33 of the base portion 31. Each first mounting hole 41 is formed to penetrate the base portion 31 in the axial direction. The multiple first mounting holes 41 are arranged at equal intervals in the circumferential direction. The crankshaft 4, which will be described later and constitutes the reduction gear 10, is inserted into the first mounting holes 41.

[0026] The first mounting hole 41 has, in order from the axial inner side, a first crank insertion hole 42, a ring storage recess 46, and a through hole 45. These first crank insertion hole 42, ring storage recess 46, and through hole 45 are formed in a circular shape when viewed from the axial direction. The first crank insertion hole 42, ring storage recess 46, and through hole 45 are each formed coaxially and are connected to each other.

[0027] The ring storage recess 46 is formed with its bottom surface 46a facing away from the first crank insertion hole 42. The ring storage recess 46 has a small-diameter recess 43 formed on the bottom surface 46a side and a large-diameter recess 44 formed closer to the first crank insertion hole 42 than the small-diameter recess 43. The inner diameter of the small-diameter recess 43 is smaller than the inner diameter of the first crank insertion hole 42. The outer diameter of the large-diameter recess 44 is larger than the first crank insertion hole 42. Therefore, the bottom surface 44a of the large-diameter recess 44 becomes a stepped surface 47 formed at the boundary between the small-diameter recess 43 and the large-diameter recess 44. The through hole 45 connects the bottom surface 46a of the ring storage recess 46 to the outer end surface 30a on the axial side of the substrate portion 30. The inner diameter of the through hole 45 is smaller than the inner diameter of the small diameter recess 43.

[0028] Of the ring housing recesses 46 configured in this way, the first crank insertion hole 42 is fitted with the first crank bearing 7A for rotatably supporting the crankshaft 4. The ring housing recess 46 also houses a distance ring 80 that restricts the axial movement of the crankshaft 4. A seal cap 12 is attached to the through hole 45 from the axial outside. Details of the first crank bearing 7A and the distance ring 80 will be described later.

[0029] Multiple support columns, not shown, are arranged between adjacent first mounting holes 41 in the circumferential direction. The end plate portion 50 of the support column abuts against the tip surface of the end plate portion 50.

[0030] The end plate portion 50 is positioned on the second outer ring holding surface 23 side of the case 2. The end plate portion 50 is fixed by bolts (not shown) in a state where it abuts against a support column (not shown) of the base plate portion 30. That is, the end plate portion 50 is positioned at a distance from the base plate portion 30 equal to the axial height of the support column. The base plate portion 30 and the end plate portion 50 are integrated.

[0031] The end plate portion 50 is formed in a disc shape. On the outer circumferential surface of the end plate portion 50, a second inner ring retaining surface 52 is formed on the axially inward side (towards the base plate portion 30) via a stepped surface 53. The outer diameter of the second inner ring retaining surface 52 is smaller than the outer diameter of the axially outward side of the end plate portion 50. The inner ring 62 of the main bearing 6 is fitted onto the second inner ring retaining surface 52. As a result, the end plate portion 50 is rotatably supported relative to the case 2. The inner ring 62 is positioned axially by the stepped surface 53.

[0032] Radially inward from the second inner ring holding surface 52 of the end plate portion 50, the same number of second mounting holes 54 as the first mounting holes 41 are formed. Each second mounting hole 54 is formed to penetrate the end plate portion 50 in the axial direction. Each second mounting hole 54 is arranged coaxially with the first mounting hole 41. The crankshaft 4, described later, is inserted into the second mounting hole 54. In the second mounting hole 54, a second crank insertion hole 55 and a female threaded portion 56 are formed in order from the axial inner side. The second crank insertion hole 55 is formed in a circular shape when viewed from the axial direction. The second crank insertion hole 55 and the female threaded portion 56 are formed coaxially and are connected to each other.

[0033] The effective diameter of the female thread portion 56 is larger than the inner diameter of the second crank insertion hole 55. A second crank bearing 7B, which rotatably supports the crankshaft 4, is fitted into the second crank insertion hole 55. Details of the second crank bearing 7B will be described later. An annular retaining bolt 16 is tightened into the female threaded portion 56. The retaining bolt 16 prevents the crankshaft 4 from coming loose from the second mounting hole 54, which will be described later.

[0034] <Deceleration part> The reduction gear 10 is a so-called eccentric oscillating type reduction gear. Specifically, the reduction gear 10 mainly consists of two external gears 5A and 5B (first external gear 5A, second external gear 5B) that are rotatably mounted on the crankshafts 4, in addition to the internal tooth pins 25 and the multiple (three in this embodiment) crankshafts 4 that are inserted through the respective mounting holes 41 and 54.

[0035] The crankshaft 4 has a first journal portion 71 rotatably supported on the base portion 30 via a first crank bearing 7A, a second journal portion 72 rotatably supported on the end plate portion 50 via a second crank bearing 7B, two eccentric portions 73 and 74 (first eccentric portion 73, second eccentric portion 74) formed on the axially inward side of each journal portion 71 and 72, and a small diameter portion 75 protruding axially outward from the second journal portion 72.

[0036] Of the two eccentric portions 73 and 74, the first eccentric portion 73 is positioned alongside the first journal portion 71. Of the two eccentric portions 73 and 74, the second eccentric portion 74 is positioned alongside the second journal portion 72. Each eccentric portion 73 and 74 is eccentric with respect to the crank rotation axis A2 of the crankshaft 4. The crank rotation axis A2 is parallel to the carrier rotation axis A1 (axial direction). Each eccentric portion 73 and 74 is positioned such that they have a phase difference of a predetermined angle (180° in this embodiment) from each other.

[0037] The small-diameter portion 75 protrudes axially outward from the end plate portion 50. A spur gear 17, for example, is attached to this protruding portion. This spur gear 17 meshes with an input gear 18, which receives rotation from an external motor (not shown). As a result, the rotational force of the external motor (the rotational force of the input gear 18) is transmitted to the crankshaft 4 via the spur gear 17.

[0038] The two external gears 5A and 5B are formed in a disc shape so as to fit between the base portion 31 and the end plate portion 50 of the base plate portion 30. The two external gears 5A and 5B are arranged axially side by side between the base portion 31 and the end plate portion 50. Of the two external gears 5A and 5B, the first external gear 5A is located on the base portion 31 side. Of the two external gears 5A and 5B, the second external gear 5B is located on the end plate portion 50 side.

[0039] External teeth 77 are formed on the outer circumference of the two external gears 5A and 5B, respectively, which mesh with internal tooth pins 25 provided on the case 2. The number of teeth on each external tooth 77 is, for example, one less than the number of internal tooth pins 25. The two external gears 5A and 5B have multiple shaft insertion holes 78 through which each crankshaft 4 is inserted separately. A first eccentric portion 73 is attached to each shaft insertion hole 78 of the first external gear 5A via a first eccentric bearing 8A. A second eccentric portion 74 is attached to each shaft insertion hole 78 of the second external gear 5B via a second eccentric bearing 8B.

[0040] <Crank bearings and eccentric bearings> Each crank bearing 7A, 7B and each eccentric bearing 8A, 8B are so-called needle bearings. These bearings 7A, 7B, 8A, and 8B are integrated with a part of the section that provides rotatable support.

[0041] In other words, the first crank bearing 7A comprises an annular inner ring 63a integrated with the first journal portion 71, an annular outer ring 64a integrated with the base plate portion 30 to form the first crank insertion hole 42, a plurality of rolling elements 65a positioned between the inner ring 63a and the outer ring 64a, and a cage 66a that holds the plurality of rolling elements 65a. The second crank bearing 7B comprises an annular inner ring 63b integrated with the second journal portion 72, an annular outer ring 64b integrated with the end plate portion 50 to form the second crank insertion hole 55, a plurality of rolling elements 65b positioned between the inner ring 63b and the outer ring 64b, and a cage 66b that holds the plurality of rolling elements 65b.

[0042] The first eccentric bearing 8A comprises an annular inner ring 67a integrated with the first eccentric portion 73, an annular outer ring 68a integrated with the first external gear 5A to form a shaft insertion hole 78, a plurality of rolling elements 69a positioned between the inner ring 67a and the outer ring 68a, and a cage 70a that holds the plurality of rolling elements 69a. The second eccentric bearing 8B comprises an annular inner ring 67b integrated with the second eccentric portion 74, an annular outer ring 68b integrated with the second external gear 5B to form a shaft insertion hole 78, a plurality of rolling elements 69b positioned between the inner ring 67b and the outer ring 68b, and a cage 70b that holds the plurality of rolling elements 69b. Each of the rolling elements 65a, 65b, 69a, and 69b is a needle-shaped roller arranged parallel to the axial direction.

[0043] In the crankshaft 4 configured in this way, the distance ring 80 housed in the ring housing recess 46 abuts against the first axially outer end face 71a of the first journal portion 71. The pull-out bolt 16 tightened to the female thread portion 56 of the end plate portion 50 abuts against the second axially outer end face 72a of the second journal portion 72. This restricts the axial movement of the crankshaft 4 relative to the carrier 3.

[0044] <Distance Ring> Next, the details of the distance ring 80 will be described based on Figures 2 to 5. Figure 3 is a perspective view of the distance ring 80 from the axial outside. Figure 4 is a plan view of the distance ring 80 from the axial outside. Figure 5 is a perspective view of the distance ring 80 from the axial inside.

[0045] The distance ring 80 is formed in a porous state. Here, "porous" refers to a state in which oil is impregnable, and includes sintered metals and oil-impregnating resins. In other words, a porous state means that a lubricant can be impregnated into it. For example, the sintered metal may be formed by any of the following methods: powder sintering, laminated sintering of wire mesh or etched plate, fiber sintering, etc. As the sintered metal material, iron, stainless steel, copper alloy, aluminum alloy, nickel, nickel alloy, titanium, molybdenum, tungsten, tantalum, zirconium boride, etc. can be used, but a material with excellent wear resistance may be selected from among these.

[0046] As shown in Figures 2 to 5, the distance ring 80 is integrally molded with a cylindrical portion 81 that fits into a small-diameter recess 43 of the ring housing recess 46, and a flange portion 82 that protrudes radially outward from the axially inward end of the cylindrical portion 81. The outer diameter of the cylindrical portion 81 is slightly smaller than the inner diameter of the small-diameter recess 43. The cylindrical portion 81 has four cylindrical grooves (an example of the second groove in the claim) 83 formed therein, which are arranged at equal intervals in the circumferential direction. The cylindrical grooves 83 have an outer peripheral groove 84 formed axially along the outer peripheral surface 81a of the cylindrical portion 81, and an end face groove 85 formed radially along the outer end face 81b on the axially outer side of the cylindrical portion 81. The outer peripheral groove 84 and the end face groove 85 are connected.

[0047] In the outer groove 84, the widths of the two inner surfaces 84a that face each other in the circumferential direction gradually increase as they move away from the bottom surface 84b, that is, as they move radially outward. In other words, the two inner surfaces 84a are formed obliquely such that their circumferential width gradually increases as they move radially outward. A rounded chamfer 86a is formed at the corner between the inner surface 84a and the outer surface 81a such that the cross-section along the radial direction is arc-shaped. An arcuate surface 86b is formed at the corner between the inner surface 84a and the bottom surface 84b such that the cross-section along the radial direction is arc-shaped.

[0048] In the end face groove 85, the widths of the two inner surfaces 85a that face each other in the circumferential direction gradually increase as they move away from the bottom surface 85b, that is, as they move outward in the axial direction. In other words, the two inner surfaces 85a are formed obliquely such that their axial width gradually increases as they move outward in the axial direction. In addition, the cylindrical portion 81 has a first beveled portion 89a formed at the corner between the outer circumferential surface 81a and the outer end surface 81b. A second beveled portion 89b is formed at the corner between the inner circumferential surface 81c and the outer end surface 81b. These beveled portions 89a and 89b are formed flat.

[0049] The flange portion 82 is housed in the large-diameter recess 44 of the ring housing recess 46. The outer diameter of the flange portion 82 is larger than the inner diameter of the small-diameter recess 43 and smaller than the inner diameter of the large-diameter recess 44. Therefore, the outer circumferential surface 82a of the flange portion 82 does not come into contact with the inner circumferential surface of the large-diameter recess 44. Four flange side grooves (an example of the first groove in the claim) 87 are formed on the outer circumferential surface 82a of the flange portion 82. The four flange side grooves 87 are arranged at equal intervals in the circumferential direction so as to be aligned with the cylindrical side groove 83 in the axial direction.

[0050] In the flange side groove 87, the widths of the two inner surfaces 87a that face each other in the circumferential direction gradually increase as they move away from the bottom surface 87b, that is, as they move radially outward. In other words, the two inner surfaces 87a are formed obliquely such that their circumferential width gradually increases as they move radially outward.

[0051] A rounded chamfer 88a is formed at the corner between the inner surface 87a and the outer surface 82a of the flange portion 82, such that the cross-section along the radial direction is arc-shaped. An arcuate surface 88b is formed at the corner between the inner surface 87a and the bottom surface 87b, such that the cross-section along the radial direction is arc-shaped. This arcuate surface 88b is formed to be the same shape as the arcuate surface 86b of the outer groove 84 and is continuous with the arcuate surface 86b of the outer groove 84.

[0052] At the corner between the outer end surface 82b on the axial side of the flange portion 82 and the outer circumferential surface 81a of the cylindrical portion 81, an arcuate surface 91a is formed such that the cross-section along the axial direction is arc-shaped. A rounded chamfer portion 91b is formed on the periphery of the outer end surface 82b such that the cross-section along the axial direction is arc-shaped. A stepped surface 92 is formed on the outer edge of the inner end face 82c on the axially inward side of the flange portion 82. The stepped surface 92 is recessed from the inner end face 82c and is located axially outward from the inner end face 82c.

[0053] In this configuration, the outer end surface 81b of the cylindrical portion 81 abuts against the bottom surface 46a of the ring housing recess 46 of the distance ring 80. In addition, the first end surface 71a of the crankshaft 4 abuts against the inner end surface 82c of the flange portion 82 of the distance ring 80. Furthermore, the cage 66a of the first crank bearing 7A abuts against the inner end surface 82c of the flange portion 82. As a result, the crankshaft 4 and the first crank bearing 7A are positioned via the distance ring 80. Consequently, the first crank bearing 7A is also positioned relative to the crankshaft 4.

[0054] <Regarding the inclusion of lubricant> Next, the process of sealing a lubricant (not shown) into the reduction gear 1 will be explained based on Figures 1 and 2. As shown in Figures 1 and 2, when a lubricant (not shown) is sealed inside the reduction gear 1, the lubricant is injected into the carrier 3 through the second crank insertion hole 55 of the end plate portion 50. The end plate portion 50 side is the side to which the rotational force (power) of an external motor (not shown) is input to the crankshaft 4. When the lubricant is injected, the seal cap 12 is removed.

[0055] The injected lubricant penetrates the interior through the space between the crankshaft 4 and the carrier 3 and the outer gears 5A and 5B. In other words, the lubricant penetrates the interior of the carrier 3 through each bearing 7A, 7B, 8A, and 8B. When lubricant is injected, the internal volume of the space inside the carrier 3 decreases, and the internal pressure tends to increase. In this case, the increased internal pressure acts as resistance, making it difficult for the lubricant to penetrate the interior of the carrier 3.

[0056] Incidentally, a distance ring 80 is provided on the base plate portion 30 opposite to the end plate portion 50 where the lubricant is injected. The outer end surface 81b of the cylindrical portion 81 abuts against the bottom surface 46a of the ring storage recess 46 of the distance ring 80, and the first end surface 71a of the crankshaft 4 abuts against the inner end surface 82c of the flange portion 82. As a result, the distance ring 80 blocks the flow of lubricant and air in the first crank insertion hole 42 where the first crank bearing 7A is provided and the ring storage recess 46 leading to this crank insertion hole 42.

[0057] However, the distance ring 80 has a cylindrical groove 83 and a flange groove 87 formed therein. This creates a passage 95 that runs between the inner end face 82c of the distance ring 80 and the through hole 45. As a result, lubricant and air flow to the outside of the substrate portion 30 through the passage 95 (see arrow Y in Figure 2). Therefore, it is possible to prevent the internal pressure of the carrier 3 from rising and to properly inject lubricant into the interior of the carrier 3.

[0058] Furthermore, the inner surfaces 84a and 85a of the cylindrical side groove 83 are formed at an angle such that their circumferential width gradually increases as they move away from the bottom surfaces 84b and 85b. The two inner surfaces 87a of the flange side groove 87 are formed at an angle such that their circumferential width gradually increases as they move away from the bottom surface 87b. As a result, the cross-sectional area of ​​the passage 95 can be made as large as possible. Therefore, the fluidity of air and lubricant can be improved, and lubricant can be injected into the carrier 3 more smoothly.

[0059] Since the distance ring 80 is formed in a porous manner, the lubricant is sufficiently impregnated into the distance ring 80. After sealing a lubricant (not shown) inside the reduction gear 1, a seal cap 12 is attached to the through hole 45. This completes the lubricant sealing process.

[0060] <Operation of the speed reducer> Next, the operation of the reduction gear 1 will be explained. When an external motor (not shown) is driven, the three crankshafts 4 are rotated simultaneously via the input gear 18 and the spur gear 17. This causes the first eccentric part 73 to rotate eccentrically, and in conjunction with the eccentric rotation of the first eccentric part 73, the first external gear 5A oscillates around the crank rotation axis A2 while meshing with a portion of the internal tooth pin 25. In addition, the second eccentric part 74 rotates eccentrically, and in conjunction with the eccentric rotation of the second eccentric part 74, the second external gear 5B oscillates around the crank rotation axis A2 while meshing with a portion of the internal tooth pin 25.

[0061] Each external gear 77 has one fewer tooth than, for example, the number of internal pins 25. Therefore, each external gear 5A, 5B rotates such that the meshing points of each external gear 77 with respect to the internal pins 25 (case 2) are sequentially shifted in the circumferential direction. This rotation is decelerated relative to the rotation of the crankshaft 4.

[0062] As each external gear 5A and 5B rotates, each crankshaft 4 also rotates on its own axis around the crank rotation axis A2 while revolving around the carrier rotation axis A1. Each crankshaft 4 is rotatably supported on the carrier 3 (base plate portion 30, end plate portion 50). Therefore, the carrier 3 rotates in conjunction with the revolution of each crankshaft 4. In this case, if the case 2 is fixed to, for example, an external device (not shown), the carrier 3 will reduce the rotation of, for example, an external motor (not shown) relative to the case 2 and output it.

[0063] Here, the crankshaft 4 rotates in conjunction with the oscillating rotation of the external gears 5A and 5B, generating a skew force F (see Figure 2) toward the base plate 30. This causes the first end face 71a of the crankshaft 4 to press against the inner end face 82c of the distance ring 80. Since no grooves or the like are formed on the inner end face 82c of the distance ring 80, it is possible to prevent an increase in the surface pressure on the crankshaft 4 and the first crank bearing 7A that press against the distance ring 80.

[0064] The distance ring 80, which is pressed against the crankshaft 4, may rotate along with the crankshaft 4. In this case, the cylindrical portion 81 of the distance ring 80 is simply fitted into the small-diameter recess 43 of the ring housing recess 46. Therefore, compared to the case where the entire outer surface of the distance ring 80 is fitted into the entire inner surface of the ring housing recess 46, the sliding resistance of the distance ring 80 against the base plate portion 30 can be reduced.

[0065] Furthermore, the distance ring 80 has rounded chamfered portions 86a, 88a, 91b and flat chamfered portions 89a, 89b. The inner surfaces 84a, 85a of the cylindrical side groove 83 are formed at an angle such that the circumferential width gradually increases as it moves away from the bottom surfaces 84b, 85b. As a result, the distance ring 80 does not get caught in the ring storage recess 46 when it rotates together.

[0066] Since a stepped surface 92 is formed on the outer edge of the inner end surface 82c of the distance ring 80, it is possible to avoid strong contact between the distance ring 80 and the cage 66a of the first crank bearing 7A.

[0067] As described above, in the reduction gear 1, the distance ring 80 has a cylindrical groove 83 and a flange groove 87. This allows for the formation of a passage 95 between the inner end face 82c of the distance ring 80 and the through hole 45. This prevents the internal pressure of the carrier 3 from rising and allows for the proper injection of lubricant into the interior of the carrier 3.

[0068] The ring storage recess 46 has a small-diameter recess 43 formed on the bottom surface 46a side and a large-diameter recess 44 formed on the first crank insertion hole 42 side of the small-diameter recess 43. The distance ring 80 is integrally molded with a cylindrical portion 81 that fits into the small-diameter recess 43 and a flange portion 82 that is housed in the large-diameter recess 44. As a result, the distance ring 80 can be made as small as possible. This makes it easier to secure the wall thickness of the carrier 3 in the area where the distance ring 80 is provided. For example, it is easier to secure the wall thickness of the base plate portion 30 in the area of ​​the distance ring 80 that corresponds to the flange portion 82. As a result, it is also possible to miniaturize the reduction gear 1.

[0069] Furthermore, to restrict the radial movement of the distance ring 80, for example, the small-diameter recess 43 and the cylindrical portion 81 can be fitted together. A gap may be left between the large-diameter recess 44 and the flange portion 82. In this case, the sliding resistance of the distance ring 80 against the carrier 3 can be reduced. This makes it possible to improve the driving efficiency of the crankshaft 4 that contacts the distance ring 80, for example.

[0070] The distance ring 80 has an outer groove 84 formed on the outer circumferential surface 81a of the cylindrical portion 81 and an end groove 85 formed on the outer end surface 81b, in order to allow passage between the first end face 71a of the crankshaft 4 and the through hole 45. A flange side groove 87 is formed on the outer circumferential surface 82a of the flange portion 82. Therefore, compared to the case where a groove is formed on the inner end surface 82c of the distance ring 80, it is possible to prevent the surface pressure on the cage 66a of the first crank bearing 7A and the surface pressure on the first end face 71a of the crankshaft 4 from becoming excessive. Thus, damage to the first crank bearing 7A and the crankshaft 4 can be prevented.

[0071] Furthermore, by simply forming grooves 84, 85, and 87 on the outer peripheral surfaces 81a, 82a and the outer end surface 81b, respectively, the distance ring 80 can be passed through the inside and outside of the carrier 3. This makes it easy to manufacture the distance ring 80.

[0072] Each inner surface 84a, 85a of the cylindrical side groove 83 is formed at an angle such that its circumferential width gradually increases as it moves away from the bottom surface 84b, 85b. The two inner surfaces 87a of the flange side groove 87 are formed at an angle such that their circumferential width gradually increases as they move away from the bottom surface 87b. As a result, the cross-sectional area of ​​the passage 95 can be made as large as possible. Therefore, the fluidity of air and lubricant can be improved, and lubricant can be injected into the interior of the carrier 3 more smoothly.

[0073] A stepped surface 92 is formed on the outer edge of the inner end face 82c of the distance ring 80. In other words, a stepped surface 92 is formed at the corner of the flange side groove 87 on the side of the first crank insertion hole 42. A rounded chamfered portion 86a is formed at the corner between the inner surface 84a and the outer surface 81a of the cylinder side groove 83. By the way, when flange side grooves 87 and cylindrical side grooves 83 are formed, edges are created. These edges could catch on the retainer 66a and ring storage recess 46, potentially damaging the retainer 66a and ring storage recess 46. However, by forming stepped surfaces 92 and rounded chamfers 86a, damage to the retainer 66a and ring storage recess 46 can be suppressed.

[0074] The distance ring 80 is formed in a porous manner. Therefore, the distance ring 80 can be sufficiently impregnated with lubricant. As a result, the sliding resistance between the distance ring 80 and the crankshaft 4, the sliding resistance between the distance ring 80 and the first crank bearing 7A, and the sliding resistance between the distance ring 80 and the base plate portion 30 can be reduced.

[0075] The present invention is not limited to the embodiments described above, but includes various modifications to the embodiments described above, without departing from the spirit of the invention.

[0076] For example, in the above embodiment, the reduction gear 1, as an eccentric oscillating type reduction gear, was described as having three crankshafts 4 and two external gears 5A and 5B. The case in which the two external gears 5A and 5B are oscillating and rotating by the three crankshafts 4 was described. However, it is not limited to this, and it is sufficient to have at least one crankshaft 4. It is also sufficient to have at least one external gear 5A and 5B.

[0077] In the above-described embodiment, the distance ring 80 was described in a case where the cylindrical portion 81 and the flange portion 82 are integrally molded. However, it is not limited to this, and the distance ring 80 can take on various shapes. For example, the distance ring 80 may be formed in a simple annular or disc shape. In this case, grooves may be formed on the outer circumferential surface of the distance ring 80 and on the end face on the bottom surface 46a side of the ring housing recess 46, forming a passage 95 that connects the inner end face 82c of the distance ring 80 to the through hole 45.

[0078] Furthermore, when forming the passage 95, it is not necessary to form grooves on the outer circumferential surface of the distance ring 80 and on the end face on the bottom surface 46a side of the ring storage recess 46. It is sufficient if the groove passes through the inner end face 82c of the distance ring 80 and the through hole 45. For example, a hole may be formed that passes through the distance ring 80, or a groove may be formed on the inner end face 82c over its entire radial direction.

[0079] In the above-described embodiment, the case in which the distance ring 80 has rounded chamfers 86a, 88a, 91b and flat chamfers 89a, 89b was described. The case in which each inner surface 84a, 85a of the cylindrical side groove 83 is formed at an angle such that the circumferential width gradually increases as it moves away from the bottom surface 84b, 85b was described. The case in which the width of the inner surface 87a of the flange side groove 87 is formed at an angle such that the circumferential width gradually increases as it moves away from the bottom surface 87b was described. However, it is not limited to these, and the distance ring 80 does not have to have rounded chamfers 86a, 88a, 91b and flat chamfers 89a, 89b. The inner surface 84a, 85a of the cylindrical side groove 83 and the inner surface 87a of the flange side groove 87 do not have to be formed at an angle.

[0080] At a minimum, it is desirable that a stepped surface 92 is formed on the inner end surface 82c of the distance ring 80. Furthermore, it is desirable that a rounded chamfer 86a is formed at the corner between the inner surface 84a and the outer surface 81a of the cylindrical side groove 83. This configuration helps to prevent damage to the retainer 66a and the ring storage recess 46. Instead of the stepped surface 92, a chamfered portion may be formed on the inner end surface 82c of the distance ring 80. In other words, it is sufficient that the outer edge of the inner end surface 82c is recessed from the inner end surface 82c.

[0081] The case described above involves the distance ring 80 having four cylindrical side grooves 83 and four flange side grooves 87. However, it is not limited to this case; at least one of each groove 83, 87 is sufficient.

[0082] In the above-described embodiment, the case in which the distance ring 80 has rounded chamfers 86a, 88a, 91b or flat chamfers 89a, 89b has been described. However, it is not limited to this, and various chamfer shapes can be used. The only requirement is that the distance ring 80 does not get caught in the ring storage recess 46 by forming the chamfers. For example, rounded chamfers may be used instead of flat chamfers 89a, 89b.

[0083] For example, the case described above was one in which the rounded chamfered portions 86a, 88a, and 91b are formed to have an arc-shaped cross-section. However, this is not the only case, and flat chamfered portions may be formed instead of the rounded chamfered portions 86a, 88a, and 91b. The cross-section of the rounded chamfered portions 86a, 88a, and 91b may be formed to be an arc shape rather than an arc shape.

[0084] Among the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective. [Explanation of Symbols]

[0085] 1...Reduction device 2…case 3… Career 4…Crankshaft 5A...First external gear (external gear) 5B... Second external gear (external gear) 7A…First crank bearing (bearing) 7B...Second crank bearing (bearing) 21...Internal gear section (internal gear) 25... Internal gear pin (internal gear) 42…First crank insertion hole (crank insertion hole) 43... Small diameter recess 44...Large diameter recess 45…Through hole 46... Ring storage recess 46a...Bottom surface (recessed bottom surface) 55…Second crank insertion hole (crank insertion hole) 80... Distance Ring 81...Cylindrical section 81a...Outer surface 81b...Outer end face (end face on the recess side) 82…Flange section 82a...Outer surface 84…Outer perimeter grooves (1st groove, 2nd groove) 85...End groove (second groove) 86a... Rounded chamfered section 87…Flange side groove (first groove) 88a... Rounded chamfered section 89a...First planar section 89b...Second planar section 91b... Rounded chamfered section 92...Step surface 95…Passageway

Claims

1. A cylindrical case having an internal gear, A carrier is positioned radially inside the case and is rotatably supported by the case, The carrier is rotatably supported via bearings, and an external rotational force is input to at least one crankshaft, An external gear housed in the carrier and rotatably supported on the crankshaft, and meshing with the internal gear, Equipped with, The aforementioned carrier, The crank insertion hole into which the bearing is fitted, A ring storage recess is formed coaxially with the crank insertion hole and is connected to the crank insertion hole, A through hole that allows the bottom surface of the recess in the ring storage recess to pass through to the outside of the carrier, It has, The ring storage recess houses a distance ring that is used to position the crankshaft in the axial direction, The distance ring has a passage formed between the shaft-side end face on the crankshaft side and the through hole. Reduction device.

2. The aforementioned passage is The first groove formed on the outer circumferential surface of the distance ring, A second groove formed on the recess-side end face of the recess on the bottom surface side of the distance ring, including, The speed reduction device according to claim 1.

3. At least a portion of the corner of the first groove and at least a portion of the corner of the second groove are chamfered so that their cross-section is arc-shaped. The reduction gear according to claim 2.

4. The aforementioned ring storage recess is A small-diameter recess formed on the bottom surface side of the recess, A larger diameter recess formed on the crank insertion hole side of the smaller diameter recess, It has, The diameter of the large-diameter recess is larger than the diameter of the small-diameter recess. The aforementioned distance ring is A cylindrical portion that fits into the aforementioned small-diameter recess, A flange portion formed on the crank insertion hole side of the cylindrical portion and housed in the large-diameter recess, It has, The flange portion protrudes radially outward from the cylindrical portion. The aforementioned passage is The first groove formed on the outer circumferential surface of the flange portion, A second groove formed on the outer circumferential surface of the cylindrical portion and on the recess-side end surface of the cylindrical portion on the bottom surface of the recess, including, The speed reduction device according to claim 1.

5. The width between the two opposing inner surfaces of the first groove and the second groove, respectively, gradually increases as it moves away from the first groove bottom surface of the first groove and the second groove bottom surface of the second groove. The speed reduction device according to claim 4.

6. Of the first groove, at least the corner on the crank insertion hole side is formed to be recessed from the shaft-side end face of the distance ring, Of the second groove, at least the corners on the outer circumferential surface side of the cylindrical portion are chamfered. The reduction gear according to claim 5.

7. The distance ring is formed in a porous manner. A speed reduction device according to any one of claims 1 to 6.

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