Gear device

Abstract

A gear device (1) according to one embodiment of the present invention is provided with: a cylindrical housing (2) having an internally toothed pin (5); a substrate part (7) rotatably supported by the housing (2) via a first main bearing (41); an end plate section (8) rotatably supported by the housing (2) via a second main bearing (42); a crankshaft (13) which is rotatably supported by the base plate part (7) and the end plate part (8) and to which an external rotational force is input; and externally toothed gears (15, 16) that are disposed between the base plate section (7) and the end plate section (8) and that mesh with the internally toothed pins (5). The base plate portion (7) is provided with a base plate protrusion (51) which abuts against the end face (15e) of the first external gear (15), and the end plate portion (8) is provided with an end plate protrusion (62) which abuts against the end face (16e) of the second external gear (16).

Description

Technical Field

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

[0002] Conventionally, a so-called eccentric oscillating type reduction gear is known as a gear transmission. This reduction gear transmission comprises: an internally toothed gear; two gear carriers rotatably supported by the internally toothed gear via bearings and disposed opposite each other in the direction of the rotation axis; a crankshaft rotatably supported by the gear carriers and having an eccentric portion; and an externally toothed gear (oscillating gear) disposed between the gear carriers, rotatably supported by the crankshaft, and meshing with the internally toothed gear.

[0003] To improve the driving efficiency of such gear devices, various technologies have been proposed for distributing lubricant throughout the gear device while restricting axial movement of the externally toothed gear. For example, a technology has been disclosed in which one of the two gear carriers is provided with a protrusion that abuts the axial end face of the externally toothed gear (see, for example, Patent Document 1).

[0004] The convex portions can be formed along the entire circumference or arranged intermittently and discretely along the circumference. This configuration allows the convex portions to restrict axial movement of the externally toothed gear. Furthermore, a gap corresponding to the convex portions can be maintained between the externally toothed gear and the gear carrier. Lubricant can flow throughout the gear device through this gap.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-124730 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, in the above-mentioned prior art, there is a portion where the bearing and the external gear abut, which hinders the flow of lubricant. Therefore, the lubricant cannot be fully distributed throughout the entire gear device, which may make it difficult to reliably improve the driving efficiency of the gear device.

[0010] The present invention provides a gear device capable of reliably improving driving efficiency.

[0011] Solutions for solving problems

[0012] The gear device of one technical solution of the present invention comprises: a cylindrical housing having an internal gear; a first gear frame arranged on the radial inner side of the housing and supported by the housing in a rotatable manner by a first bearing; a second gear frame arranged on the radial inner side of the housing and opposite to the first gear frame in the axial direction of the housing, and supported by the housing in a rotatable manner by a second bearing; at least one crankshaft rotatably supported by the first gear frame and the second gear frame, to which external rotation is input force; and at least one external gear, which is arranged between the first gear frame and the second gear frame and meshes with the internal gear, the crankshaft comprising: a shaft body; and an eccentric portion, which is provided on the shaft body and eccentric with respect to the rotation axis of the shaft body, the external gear being supported on the eccentric portion in a rotatable manner, the first gear frame comprising a first protrusion abutting the end face of the external gear on the first gear frame side, and the second gear frame comprising a second protrusion abutting the end face of the external gear on the second gear frame side.

[0013] With this structure, the first and second protrusions can be used to restrict the axial movement of the externally toothed gear. The first protrusion can ensure a gap between the externally toothed gear and the first gear carrier. The second protrusion can also ensure a gap between the externally toothed gear and the second gear carrier. In this way, gaps can be ensured on both sides of the axial direction of the swinging externally toothed gear. Therefore, while restricting the axial movement of the externally toothed gear, lubricant can be fully distributed throughout the entire gear unit. This reliably improves the driving efficiency of the gear unit.

[0014] In the above structure, the first bearing and the second bearing may include: an outer ring, which is provided in the housing; an inner ring, which is arranged on the radial inner side of the outer ring and is provided on the corresponding first gear frame or the second gear frame; and a plurality of rolling elements, which are arranged between the outer ring and the inner ring, the first protrusion protruding to a position closer to the external gear side than the inner ring of the first bearing, and the second protrusion protruding to a position closer to the external gear side than the inner ring of the second bearing.

[0015] In the above configuration, a plurality of the first convex portions and a plurality of the second convex portions may be provided, and the plurality of the first convex portions and the plurality of the second convex portions may be arranged to be staggered with each other in the circumferential direction when viewed from the axial direction.

[0016] In the above structure, the first protrusion may be provided on the outer periphery of the surface of the first gear frame axially opposite to the external gear, and the second protrusion may be provided on the outer periphery of the surface of the second gear frame axially opposite to the external gear.

[0017] In the above structure, the first gear rack may include a plurality of column portions that protrude toward the second gear rack for maintaining a constant interval between the first gear rack and the second gear rack, and the first protrusion is at least provided at a position radially outward of the column portions.

[0018] In the above configuration, the second gear carrier may include a base surface on which the front end of the column portion abuts, and the front end surface of the second protrusion and the base surface may be arranged on the same plane.

[0019] In the above structure, the internal gear may include a plurality of internal pins provided on the inner peripheral surface of the housing and arranged at equal intervals in the circumferential direction, and parts of the axial end faces of the internal pins abut against the first bearing and the second bearing.

[0020] Effects of the Invention

[0021] The above-mentioned gear device can reliably improve driving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a cross-sectional view of a reduction gear transmission according to an embodiment of the present invention.

[0023] Figure 2 This is a plan view of the base plate portion according to the embodiment of the present invention as viewed from the end plate portion side.

[0024] Figure 3 This is a plan view of the end plate portion according to the embodiment of the present invention as viewed from the base plate portion side.

[0025] Figure 4 This is a plan view of the base plate portion according to the first modified example of the embodiment of the present invention as viewed from the end plate portion side.

[0026] Figure 5 This is a plan view of the end plate portion according to the first modified example of the embodiment of the present invention as viewed from the base plate portion side.

[0027] Figure 6 This is a plan view of an end plate portion according to a second modified example of the embodiment of the present invention as viewed from the base plate portion side.

[0028] Figure 7 This is a plan view of a base plate portion according to a third modified example of the embodiment of the present invention as viewed from the end plate portion side.

[0029] Figure 8 This is a plan view of an end plate portion according to a third modified example of the embodiment of the present invention as viewed from the base plate portion side.

[0030] Figure 9This is a plan view of a base plate portion according to a fourth modified example of the embodiment of the present invention as viewed from the end plate portion side.

[0031] Figure 10 This is a plan view of an end plate portion according to a fourth modified example of the embodiment of the present invention as viewed from the base plate portion side.

[0032] Figure 11 This is a plan view of a base plate portion according to a fifth modified example of the embodiment of the present invention as viewed from the end plate portion side.

[0033] Description of Reference Numerals

[0034] 1. Speed ​​reduction device (gear device); 2. Housing; 5. Internal tooth pin (internal tooth gear); 7. Base plate portion (1st gear frame); 8. End plate portion (2nd gear frame); 9. Column portion; 13. Crankshaft; 13a. 1st eccentric portion (eccentric portion); 13b. 2nd eccentric portion (eccentric portion); 13c. Shaft body; 15. 1st external tooth gear (external tooth gear); 15e, 16e. End face; 16. 2nd external tooth gear (external tooth gear); 41. 1st main bearing (bearing); 42. 2nd main bearing (bearing); 43. Outer ring; 44. Inner ring; 45. Rolling element; 51. Base plate protrusion (1st protrusion); 51c, 62b. Front end face; 61. Base surface; 62. End plate protrusion (2nd protrusion). DETAILED DESCRIPTION

[0035] Next, embodiments of the present invention will be described with reference to the drawings.

[0036] <Reduction gear>

[0037] Figure 1 It is a cross-sectional view of the reduction gear 1 serving as a gear device.

[0038] like Figure 1 As shown, the reduction gear 1 reduces the speed of the rotation of, for example, an electric motor (not shown) and outputs the speed. The reduction gear 1 is a so-called eccentric oscillating type reduction gear. The reduction gear 1 includes a cylindrical housing 2, a gear carrier 3 rotatably arranged radially inward of the housing 2, and a reduction mechanism 4 connected to the gear carrier 3. The central axis of the housing 2 and the rotation axis of the gear carrier 3 are aligned.

[0039] In the following description, these center axes and rotational axes are collectively referred to as the first rotational axis A1. The direction parallel to the first rotational axis A1 is referred to as the axial direction. The direction of rotation of the gear carrier 3 is referred to as the circumferential direction. The radial direction of the housing 2, which is orthogonal to the axial and circumferential directions, is referred to simply as the radial direction.

[0040] <Housing>

[0041] The housing 2 is formed, for example, from ductile iron. For example, FCD450 is used as the ductile iron. An outer flange portion 2a, projecting radially outward, is integrally formed on the outer peripheral surface of the housing 2. Multiple bolt holes 2b are formed in the outer flange portion 2a. The bolt holes 2b are arranged at equal intervals in the circumferential direction. Bolts (not shown) are inserted into these bolt holes 2b and, for example, are tightened to the arm of an industrial robot to secure the reduction gear 1.

[0042] A plurality of pin grooves 2c are formed along the axial direction on the inner circumferential surface 2d of the housing 2. The pin grooves 2c are arranged at equal intervals in the circumferential direction. An internally toothed pin 5 is inserted into each pin groove 2c. The internally toothed pins 5 function as internal teeth that mesh with externally toothed gears 15 and 16 of the reduction gear mechanism 4, described later.

[0043] On the inner circumferential surface 2d of the housing 2, housing bearing retaining surfaces 22a and 22b (a first housing bearing retaining surface 22a and a second housing bearing retaining surface 22b) are formed on either side of the pin groove 2c in the axial direction, separated by stepped surfaces 21a and 21b (a first stepped surface 21a and a second stepped surface 21b). Each housing bearing retaining surface 22a and 22b is annularly formed and radially outward of the pin groove 2c. A first main bearing 41 is provided on the first housing bearing retaining surface 22a of the two housing bearing retaining surfaces 22a and 22b. A second main bearing 42 is provided on the second housing bearing retaining surface 22b of the two housing bearing retaining surfaces 22a and 22b.

[0044] The main bearings 41 and 42 have the same structure and are symmetrically arranged about the axial center of the housing 2. Therefore, in the following description, only the first main bearing 41 will be described, and the detailed structure of the second main bearing 42 will be assigned the same reference numerals as those of the first main bearing 41, and description thereof will be omitted.

[0045] The first main bearing 41 is a so-called angular contact ball bearing. It comprises an annular outer ring 43 that engages with the first housing bearing retaining surface 22a; an annular inner ring 44 positioned radially inward of the outer ring 43; a plurality of rolling elements 45 positioned between the outer ring 43 and the inner ring 44; and a retainer 46 that retains the rolling elements 45 at equal intervals in the circumferential direction.

[0046] The outer ring 43 of each main bearing 41, 42 is located closer to the center of the housing 2 in the axial direction than the inner ring 44. The opposing end faces 43a of the outer ring 43 abut against the corresponding stepped surfaces 21a, 21b. This helps position each main bearing 41, 42 in the axial direction relative to the housing 2.

[0047] The end face 43a of the outer ring 43 of each main bearing 41, 42 protrudes slightly radially inward from the pin groove 2c. A portion of the axial end of the internal gear pin 5 abuts against the protruding inner diameter end 43b of the outer ring 43. This ensures axial positioning of the internal gear pin 5.

[0048] The carrier 3 is rotatably supported by the housing 2 via the main bearings 41 and 42 .

[0049] <Gear rack>

[0050] The gear carrier 3 includes a disc-shaped base plate portion (an example of the first gear carrier in the claims) 7 and an end plate portion (an example of the second gear carrier in the claims) 8, which are arranged axially opposite to each other. The base plate portion 7 and the end plate portion 8 are formed, for example, from ductile iron. For example, FCD450 is used as the ductile iron.

[0051] <Substrate part>

[0052] Figure 2 This is a plan view of the base plate portion 7 as viewed from the end plate portion 8 side.

[0053] like Figure 1 、 Figure 2 As shown, the base plate portion 7 is formed in a disk shape. A base plate bearing retaining surface 7c is formed on the outer peripheral surface 7a of the base plate portion 7 at a location radially opposed to the first housing bearing retaining surface 22a. The base plate bearing retaining surface 7c is formed in an annular shape at a position radially inward of the outer peripheral surface 7a across the step portion 7b.

[0054] The inner ring 44 of the first main bearing 41 is fitted onto the base plate bearing retaining surface 7c. The axial end of the inner ring 44 of the first main bearing 41 abuts against the stepped portion 7b. This axial positioning of the first main bearing 41 relative to the base plate 7 is achieved. In this positioned state, the end surface 44a of the inner ring 44 of the first main bearing 41 on the end plate 8 side and the end surface 7f of the base plate 7 on the end plate 8 side are flush with each other.

[0055] A seal portion 24 is provided between the outer peripheral surface 7a of the base plate 7 and the inner peripheral surface 2d of the housing 2, on the side opposite to the end plate 8 and further from the first main bearing 41. The seal portion 24 ensures sealing between the base plate 7 and the housing 2.

[0056] A base plate shaft insertion hole 7d is formed in the radial center of the base plate portion 7. Multiple (for example, three in this embodiment) crankshaft insertion recesses 7e are formed around the base plate shaft insertion hole 7d of the base plate portion 7. Each crankshaft insertion recess 7e is formed on the end surface 7f of the base plate portion 7. The crankshaft insertion recesses 7e are arranged at equal intervals in the circumferential direction. A crankshaft bearing 18 is provided in each crankshaft insertion recess 7e. The crankshaft bearing 18 is, for example, a tapered roller bearing.

[0057] Three pillars 9 are formed on the end surface 7f of the base plate portion 7, projecting toward the end plate portion 8. The pillars 9 are formed into a triangular prism shape, with their circumferential width gradually increasing radially outward when viewed from the axial direction. Each pillar 9 is positioned between circumferentially adjacent crankshaft insertion recesses 7e. The three pillars 9 are circumferentially spaced evenly apart.

[0058] Two internally threaded portions 26 are formed on the front end surface 9a of each column portion 9. The two internally threaded portions 26 are arranged side by side in the circumferential direction. A pinhole 27 is formed on the front end surface 9a of each column portion 9 at a position radially inward of the two internally threaded portions 26. These internally threaded portions 26 and pinhole 27 are used to integrate the base plate portion 7 and the end plate portion 8 (detailed description will be given later).

[0059] A plurality of (for example, three in this embodiment) substrate protrusions (an example of the first protrusion in the claims) 51 are formed on the outer periphery of the end surface 7f of the substrate portion 7. Figure 2 In the figure, in order to easily show the shape of the substrate protrusion 51, the substrate protrusion 51 is shown with hatching (the same applies to the following modified examples).

[0060] The end face 7f of the base plate portion 7 is flush with the end face 44a of the inner ring 44 of the first main bearing 41. Therefore, the base plate protrusion 51 protrudes further toward the end plate portion 8 than the inner ring 44. The protruding height of the base plate protrusion 51 is sufficiently lower than the protruding height of the column portion 9.

[0061] Three base plate protrusions 51 are formed radially outward of each crankshaft insertion recess 7e and between circumferentially adjacent columnar portions 9. The base plate protrusions 51 are formed along the outer peripheral edge of the end surface 7f of the base plate portion 7. Specifically, the base plate protrusions 51 are formed in an arc shape centered about the first rotation axis A1 when viewed from the axial direction.

[0062] A crankshaft insertion recess 7e is disposed at the circumferential center of each substrate protrusion 51. Regarding the positional relationship between the crankshaft insertion recess 7e and each substrate protrusion 51, the peripheral edge of the crankshaft insertion recess 7e is located slightly radially outward of the radially inner inner circumferential surface 51a of the substrate protrusion 51. The inner circumferential surface 51a of the substrate protrusion 51 is located on or radially outward of the imaginary circle C passing through the radially outermost side of the column 9 centered on the first rotation axis A1. Rounded corners 51b are formed at both circumferential ends of the substrate protrusion 51. The rounded corners 51b are formed in an arc shape when viewed from the axial direction.

[0063] Such a base plate protrusion 51 restricts the axial movement of a first externally toothed gear 15 to be described later (details will be described later).

[0064] <End Plate>

[0065] Figure 3 This is a plan view of the end plate portion 8 as viewed from the base plate portion 7 side.

[0066] like Figure 1 、 Figure 3 As shown, the end plate portion 8 is formed in a circular plate shape. An end plate bearing retaining surface 8c is formed on the outer peripheral surface 8a of the end plate portion 8 at a location radially opposed to the second housing bearing retaining surface 22b. The end plate bearing retaining surface 8c is formed in an annular shape radially inward of the outer peripheral surface 8a across the step portion 8b.

[0067] The inner ring 44 of the second main bearing 42 is fitted onto the end plate bearing retaining surface 8c. The axial end of the inner ring 44 of the second main bearing 42 abuts against the stepped portion 8b. This axial positioning of the second main bearing 42 relative to the end plate 8 is achieved. In this positioned state, the end surface 44a of the inner ring 44 of the second main bearing 42 on the base plate 7 side and the end surface 8f of the end plate 8 on the base plate 7 side are flush with each other.

[0068] An end plate shaft insertion hole 8d is formed in the radial center of the end plate portion 8. The end plate shaft insertion hole 8d is arranged coaxially with the base plate shaft insertion hole 7d.

[0069] A plurality (for example, three in this embodiment) of crankshaft insertion holes 8e are formed around the end plate shaft insertion hole 8d of the end plate portion 8. The crankshaft insertion holes 8e are arranged at equal intervals in the circumferential direction. Each crankshaft insertion hole 8e is coaxial with the crankshaft insertion recess 7e of the base plate portion 7. That is, the central axis A2 of the crankshaft insertion hole 8e and the crankshaft insertion recess 7e, which are axially opposed, is parallel to the first rotation axis A1. Similar to the crankshaft insertion recess 7e, a crankshaft bearing 18 is provided in each crankshaft insertion hole 8e.

[0070] Three base surfaces 61 are formed on the end surface 8f of the end plate portion 8 at locations axially opposite to the column portion 9, and three end plate protrusions (an example of the second protrusion in the claims) 62 are formed radially outside the base surfaces 61. Figure 3 In the figure, the base surface 61 and the end plate protrusion 62 are shown with hatching in order to easily show the shapes of the base surface 61 and the end plate protrusion 62 (the same applies to the following modified examples).

[0071] The end surface 8f of the end plate portion 8 is flush with the end surface 44a of the inner ring 44 of the second main bearing 42. Therefore, the seat surface 61 and the end plate protrusion 62 protrude further toward the base plate portion 7 than the inner ring 44.

[0072] The front end face 9a of the column 9 contacts the base face 61. The base face 61 is formed to correspond to the shape of the column 9. Specifically, the base face 61 is formed in a triangular prism shape such that the circumferential width thereof gradually increases radially outward when viewed from the axial direction.

[0073] Two bolt insertion holes 63 are formed in each base surface 61. The two bolt insertion holes 63 are arranged circumferentially and coaxially with the internal thread portion 26 of the column portion 9. Bolts 91 are inserted into the two bolt insertion holes 63 from the side opposite to the base plate portion 7 and each bolt 91 is tightened into the internal thread portion 26. This secures the end plate portion 8 to the base plate portion 7. A space having a width corresponding to the height of the column portion 9 is formed between the base plate portion 7 and the column portion 9.

[0074] Each base surface 61 is provided with an end plate pin hole 64 radially inward of the bolt insertion hole 63. The end plate pin hole 64 is coaxially arranged with the stud hole 27. By inserting or press-fitting a pin 92 into these pin holes 27 and 63, the base plate portion 7 and the end plate portion 8 can be positioned with high precision.

[0075] The end plate protrusion 62 is formed along the outer periphery of the base surface 61 and the outer periphery of the end surface 8f of the end plate portion 8. That is, when viewed from the axial direction, the end plate protrusion 62 is formed in an arc shape with the first rotation axis A1 as the center. Since the end plate protrusion 62 is formed on the outer periphery of the base surface 61, the end plate protrusion 62 and the substrate protrusion 51 are arranged to be staggered with each other in the circumferential direction when viewed from the axial direction. In other words, the end plate protrusion 62 and the substrate protrusion 51 are arranged to be staggered when viewed from the axial direction. Rounded corners 62a are formed at both ends of the circumference of the end plate protrusion 62. The rounded corners 62a are formed in an arc shape when viewed from the axial direction.

[0076] The front end surface 62b of the end plate protrusion 62 is arranged on the same plane as the base surface 61. The end plate protrusion 62 restricts axial movement of the second externally toothed gear 16 described later (details will be described later).

[0077] <Reduction Mechanism>

[0078] Return to Figure 1 The reduction mechanism 4 reduces the rotation of the electric motor (not shown) at a predetermined rate, thereby rotating the gear carrier 3. The reduction mechanism 4 includes: three crankshafts 13, which are respectively inserted into the crankshaft insertion recess 7e of the base plate portion 7 and the crankshaft insertion hole 8e of the end plate portion 8; a transmission spur gear 14, which is provided at the axial end of each crankshaft 13; and two externally toothed gears 15 and 16 (a first externally toothed gear 15 and a second externally toothed gear 16), which are provided between the base plate portion 7 and the end plate portion 8.

[0079] External teeth 17 are formed on the outer periphery of the transmission spur gear 14. The external teeth 17 mesh with, for example, a motor shaft of an electric motor (not shown).

[0080] The crankshaft 13 is rotatably supported on the gear carrier 3 (base plate 7 and end plate 8) by crankshaft bearings 18. The crankshaft 13 includes a shaft body 13c that rotates about the central axis A2, and a first eccentric portion 13a and a second eccentric portion 13b formed in the axial center of the shaft body 13c. The shaft body 13c is rotatably supported on both sides of the shaft body 13c by crankshaft bearings 18 on the gear carrier 3 (base plate 7 and end plate 8).

[0081] The shaft body 13c and the transmission spur gear 14 are coaxially arranged and integrated. That is, the crankshaft 13 and the transmission spur gear 14 rotate integrally about the central axis A2. Hereinafter, the central axis A2 will be referred to as the second rotation axis A2 of the crankshaft 13.

[0082] The first eccentric portion 13a and the second eccentric portion 13b are eccentric relative to the second rotation axis A2. The first eccentric portion 13a and the second eccentric portion 13b are axially adjacent to each other between the two crankshaft bearings 18. In other words, the first eccentric portion 13a and the second eccentric portion 13b are axially adjacent to each other between the base plate portion 7 and the end plate portion 8. The first eccentric portion 13a and the second eccentric portion 13b are arranged with a phase angle of 180°.

[0083] The inner circumferential surface of each eccentric portion 13a, 13b is fitted with a roller bearing 19. The roller bearing 19 is, for example, a cylindrical roller bearing. The first externally toothed gear 15 and the second externally toothed gear 16 are rotatably supported on each crankshaft 13 via the roller bearings 19.

[0084] The first externally toothed gear 15 and the second externally toothed gear 16 are arranged in the space between the base plate portion 7 and the end plate portion 8. The first externally toothed gear 15 and the second externally toothed gear 16 overlap in the axial direction. Through-holes 15a and 16a are formed in the first externally toothed gear 15 and the second externally toothed gear 16. The outer circumferential surface of a roller bearing 19 is fitted into each through-hole 15a and 16a. As a result, when the first eccentric portion 13a and the second eccentric portion 13b oscillate due to the rotation of the crankshaft 13, the first externally toothed gear 15 and the second externally toothed gear 16 oscillate via the roller bearings 19.

[0085] Openings 15b and 16b are formed in the first externally toothed gear 15 and the second externally toothed gear 16, respectively, to prevent interference with the column portion 9. Shaft insertion holes 15c and 16c are formed in the radial centers of the first externally toothed gear 15 and the second externally toothed gear 16, respectively. External teeth 15d and 16d are formed on the outer circumferences of the first externally toothed gear 15 and the second externally toothed gear 16, respectively. The number of teeth on each of the externally toothed gears 15d and 16d is, for example, one less than the number of internally toothed pins 5 of the housing 2.

[0086] The front end surface 51c of the base plate protrusion 51 contacts the outer peripheral portion of the end surface 15e on the base plate portion 7 side of the first externally toothed gear 15. Therefore, a gap G1 is formed between the end surface 15e of the first externally toothed gear 15 and the end surface 7f of the base plate portion 7.

[0087] The front end surface 62b of the end plate protrusion 62 contacts the outer peripheral portion of the end surface 16e on the end plate 8 side of the second externally toothed gear 16. Therefore, a gap G2 is formed between the end surface 16e of the second externally toothed gear 16 and the end surface 8f of the end plate 8.

[0088] <Method for Manufacturing Base Plate and End Plate>

[0089] Next, a method for manufacturing the base plate portion 7 and the end plate portion 8 will be described.

[0090] The base plate portion 7 and the end plate portion 8 are formed by casting. Specifically, for example, molten FCD 450 is poured into a sand mold (not shown) to form the base plate portion 7 and the end plate portion 8.

[0091] Thereafter, the base plate portion 7 is subjected to cutting processing, for example, using a lathe (not shown), on the base plate bearing retaining surface 7c, the front end surface 9a of the column portion 9, and the front end surface 51c of the base plate protrusion 51. Here, the inner circumferential surface 51a of the base plate protrusion 51 is positioned on an imaginary circle C passing through the radially outermost portion of the column portion 9 centered on the first rotation axis A1, or radially outward of the imaginary circle C. Therefore, when the base plate protrusion 51 is cut using a lathe, the column portion 9 does not become an obstacle.

[0092] The end plate portion 8 is machined using, for example, a lathe (not shown) to machine the end plate bearing retaining surface 8c, the base surface 61, and the front end surface 62b of the end plate protrusion 62. The front end surface 62b of the end plate protrusion 62 is flush with the base surface 61. Therefore, the end plate protrusion 62 and the base surface 61 can be machined simultaneously.

[0093] In this manner, the manufacture of the base plate portion 7 and the end plate portion 8 is completed.

[0094] <Operation of the Speed ​​Reducer and the Role of the Base Plate and End Plate Protrusions>

[0095] Next, the operation of the reduction gear device 1 and the functions of the base plate protrusions 51 and the end plate protrusions 62 will be described.

[0096] First, the operation of the reduction gear 1 will be described.

[0097] The interior of the reduction gear 1 (inside the housing 2 and the gear carrier 3) is filled with a lubricant (not shown). In the reduction gear 1, portions of the external teeth 15d and 16d of the externally toothed gears 15 and 16 mesh with the internally toothed pins 5 of the housing 2. In this state, when the rotation of, for example, an electric motor (not shown) is transmitted to the crankshafts 13 via the transmission spur gear 14, the crankshafts 13 rotate about the second rotation axis A2.

[0098] As a result, each externally toothed gear 15, 16 oscillates and rotates. The number of teeth on each externally toothed gear 15d, 16d is, for example, one less than the number of internally toothed pins 5. Consequently, each externally toothed gear 15, 16 rotates so that the meshing points of each externally toothed gear 15d, 16d with the internally toothed pins 5 (housing 2) are sequentially offset in the circumferential direction. This rotation is reduced relative to the rotation of the crankshaft 13.

[0099] As the external gears 15 and 16 rotate, the crankshafts 13 also rotate around the first rotation axis A1 while rotating around the second rotation axis A2. The crankshafts 13 are supported on the gear rack 3 (base plate portion 7, end plate portion 8) in a rotatable manner. Therefore, the gear rack 3 rotates as the crankshafts 13 revolve. As a result, the reduction gear 1 decelerates and outputs the rotation of, for example, an electric motor not shown in the figure. Assuming that the gear rack 3 is fixed to the arm of an industrial robot, etc., the reduction gear 1 can decelerate and output the rotation of, for example, an electric motor not shown in the figure from the housing 2. In contrast, assuming that the housing 2 is fixed to the arm of an industrial robot, etc., the reduction gear 1 can decelerate and output the rotation of, for example, an electric motor not shown in the figure from the gear rack 3.

[0100] Next, the functions of the base plate protrusions 51 and the end plate protrusions 62 will be described.

[0101] The front end surface 51c of the base plate protrusion 51 contacts the base plate 7 side end surface 15e of the first externally toothed gear 15. Therefore, the base plate protrusion 51 restricts the movement of the first externally toothed gear 15 toward the base plate 7 in the axial direction.

[0102] The front end surface 62b of the end plate protrusion 62 contacts the end surface 16e of the second externally toothed gear 16 on the end plate 8 side. Therefore, the end plate protrusion 62 restricts the axial movement of the second externally toothed gear 16 toward the end plate 8 side.

[0103] Furthermore, the externally toothed gears 15 and 16 overlap in the axial direction.

[0104] Therefore, according to the above-described speed reduction device 1 , the axial movement of the externally toothed gears 15 and 16 can be restricted by the base plate protrusions 51 and the end plate protrusions 62 .

[0105] Furthermore, the base plate protrusions 51 ensure a gap G1 between the end face 15e of the first externally toothed gear 15 and the end face 7f of the base plate portion 7. The end plate protrusions 62 ensure a gap G2 between the end face 16e of the second externally toothed gear 16 and the end face 8f of the end plate portion 8. In this way, gaps G1 and G2 are ensured on both sides of the externally toothed gears 15 and 16 in the axial direction, respectively. Consequently, lubricant can be fully distributed throughout the reduction gear 1, reliably improving the driving efficiency of the reduction gear 1.

[0106] Each main bearing 41, 42 that supports the gear carrier 3 in a manner that allows it to rotate freely relative to the housing 2 includes an outer ring 43, an inner ring 44, and a plurality of rolling elements 45. The base plate protrusion 51 protrudes to a position closer to the end plate portion 8 than the inner ring 44 of the first main bearing 41. The end plate protrusion 62 protrudes to a position closer to the base plate portion 7 than the inner ring 44 of the second main bearing 42. Therefore, the base plate protrusion 51 can reliably ensure a gap between the first external gear 15 and the first main bearing 41. The end plate protrusion 62 can reliably ensure a gap between the second external gear 16 and the second main bearing 42. As a result, lubricant can be easily flowed into each main bearing 41, 42, and the driving efficiency of the reduction gear 1 can be further improved.

[0107] When viewed axially, the end plate protrusions 62 and the base plate protrusions 51 are arranged alternately in the circumferential direction. This ensures that the gaps G1 and G2 between the externally toothed gears 15 and 16 and the gear carrier 3 (base plate 7 and end plate 8) are uniformly maintained in the circumferential direction. This facilitates the distribution of lubricant throughout the reduction gear 1.

[0108] The base plate protrusion 51 is formed along the outer peripheral edge of the end surface 7f of the base plate portion 7. The end plate protrusion 62 is formed along the outer peripheral edge of the end surface 8f of the end plate portion 8. This configuration allows the protrusions 51 and 62 to abut the corresponding externally toothed gears 15 and 16 as closely as possible radially outward (toward the outer periphery). This minimizes the shaking and rattling of the externally toothed gears 15 and 16. Consequently, the driving efficiency of the reduction gear 1 can be further improved.

[0109] The inner circumferential surface 51a of the substrate protrusion 51 is located on an imaginary circle C passing through the radially outermost portion of the post 9 centered on the first rotation axis A1, or radially outward of the imaginary circle C. Therefore, when the substrate protrusion 51 is cut using a lathe, the post 9 does not become an obstacle. In other words, the front end surface 51c of the substrate protrusion 51 can be cut while avoiding the post 9. This improves the machinability of the substrate portion 7.

[0110] The front end surface 62b of the end plate convex portion 62 is arranged on the same plane as the base surface 61. Therefore, the end plate convex portion 62 and the base surface 61 can be processed simultaneously. This improves the processability of the end plate portion 8.

[0111] The end face 43a of the outer ring 43 of each main bearing 41, 42 protrudes slightly radially inward from the pin groove 2c. A portion of the axial end of the internal gear pin 5 abuts against the protruding inner diameter end 43b of the outer ring 43. Therefore, the main bearings 41, 42 can be used to position the internal gear pin 5 in the axial direction.

[0112] By making the inner diameter end 43b of the outer ring 43 abut only a portion of the axial end of the internal gear pin 5, the internal gear pin 5 can be exposed as much as possible inside the housing 2. Accordingly, the lubricant can be easily distributed over the internal gear pin.

[0113] Since the convex portions 51 and 62 respectively ensure gaps G1 and G2 between the main bearings 41 and 42 and the external gears 15 and 16, the lubricant can be further spread over the internal gear pin 5. This further improves the driving efficiency of the reduction gear 1.

[0114] In the above-mentioned embodiment, the case where the reduction mechanism 4 has three crankshafts 13 is described. Correspondingly, the case where three columnar portions 9 are protrudingly formed on the substrate portion 7 and three substrate protrusions 51 are formed is described. The case where three base surfaces 61 and three end plate protrusions 62 are formed on each end plate portion 8 is described. However, this is not limited to this. It is sufficient to have at least one crankshaft 13, and the number of substrate protrusions 51 and end plate protrusions 62 can also be at least one. The number of crankshafts 13, the number of substrate protrusions 51, and the number of end plate protrusions 62 can be determined arbitrarily. In the following, based on Figures 4 to 11 Specific examples are given for explanation.

[0115] [First Modification]

[0116] First, based on Figure 4 、 Figure 5 A first modification example will be described.

[0117] Figure 4 This is a plan view of the base plate portion 7 according to the first modified example as viewed from the end plate portion 8 side. Figure 4 With the above Figure 2 correspond. Figure 5 This is a plan view of the end plate portion 8 according to the first modification as viewed from the base plate portion 7 side. Figure 5 With the above Figure 3 correspond.

[0118] like Figure 4 、 Figure 5 As shown, for example, the reduction gear 1 may be provided with one crankshaft 13 (in Figure 4 、 Figure 5 Not shown in the figure. The same applies to the following modified examples) of the so-called center crankshaft type eccentric oscillating type speed reducer. In this case, a crankshaft 13 is arranged coaxially with the first rotation axis A1, and the external gears 15 and 16 (at Figure 4 、 Figure 5 Not shown in the figure. The same applies to the following modified examples) swing rotation.

[0119] Therefore, a crankshaft insertion recess 7e is formed in the radial center of the base plate 7. A plurality of pillars 9 (e.g., eight in the first modified example) are provided around the crankshaft insertion recess 7e.

[0120] In the first modified example, the pillars 9 are formed in a cylindrical shape. An internal thread 26 is formed on the front end face 9a of each pillar 9. A plurality (e.g., eight in this embodiment) of substrate protrusions 51 are formed on the outer periphery of the end face 7f of the substrate 7. The substrate protrusions 51 are formed between circumferentially adjacent pillars 9 along the outer periphery of the end face 7f of the substrate 7.

[0121] A crankshaft insertion hole 8e is formed in the radial center of the end plate 8. Eight seating surfaces 61 are formed on the end surface 8f of the end plate 8 at locations axially opposite the column 9, and eight end plate protrusions 62 are formed radially outward of the seating surfaces 61.

[0122] Even in the case of such a configuration, the same effects as those of the aforementioned embodiment can be achieved.

[0123] [Second Modification]

[0124] Then, based on Figure 6 A first modification example will be described.

[0125] Figure 6 This is a plan view of the end plate portion 8 according to the second modification as viewed from the base plate portion 7 side. Figure 6 With the aforementioned Figure 3 correspond.

[0126] In the first modified example described above, eight seating surfaces 61 are formed on the end surface 8f of the end plate portion 8 at locations axially opposed to the column portion 9, and eight end plate protrusions 62 are formed radially outward of the seating surfaces 61. However, this is not limiting, and the number of seating surfaces 61 and end plate protrusions 62 may not be the same as the number of column portions 9.

[0127] For example, you can also Figure 6 As shown, the number of the base surface 61 and the end plate protrusion 62 is set to 4. In this case, the connection Figure 5 The eight seat surfaces 61 and eight end plate protrusions 62 shown are formed so that two seat surfaces 61 and two end plate protrusions 62 that are adjacent in the circumferential direction are formed. That is, the seat surfaces 61 and end plate protrusions 62 of the second modified example are formed longer in the circumferential direction than those of the first modified example. The seat surfaces 61 and end plate protrusions 62 of the second modified example are formed in an arc shape centered on the first rotation axis A1 when viewed from the axial direction.

[0128] Even in the case of such a configuration, the same effects as those of the aforementioned embodiment can be achieved.

[0129] [Third Modification]

[0130] Then, based on Figure 7 、 Figure 8 A third modified example will be described.

[0131] Figure 7 This is a plan view of the base plate portion 7 according to the third modified example as viewed from the end plate portion 8 side. Figure 8 With the aforementioned Figure 2 correspond. Figure 8This is a plan view of the end plate portion 8 according to the third modification as viewed from the base plate portion 7 side. Figure 8 With the aforementioned Figure 3 correspond.

[0132] For example, you can also Figure 7 、 Figure 8 As shown, the reduction gear 1 is an eccentric oscillating type reduction gear including two crankshafts (not shown).

[0133] In this case, the base plate 7 has crankshaft insertion recesses 7e formed on either side of the first rotation axis A1. Two pillars 9 are formed protruding from the base plate 7, one between each of the circumferentially adjacent crankshaft insertion recesses 7e. Two base plate protrusions 51 are formed radially outward of each crankshaft insertion recess 7e and between the circumferentially adjacent pillars 9. The base plate protrusions 51 are formed along the outer circumferential edge of the end surface 7f of the base plate 7.

[0134] The end plate portion 8 has crankshaft insertion holes 8e formed coaxially with the crankshaft insertion recesses 7e of the base plate portion 7. A seating surface 61 and an end plate protrusion 62 are formed on the end surface 8f of the end plate portion 8, at locations axially opposed to the column portion 9. Two seating surfaces 61 and two end plate protrusions 62 are provided on either side of the first rotation axis A1 between circumferentially adjacent crankshaft insertion recesses 7e.

[0135] Even in the case of such a configuration, the same effects as those of the aforementioned embodiment can be achieved.

[0136] [Fourth Modification]

[0137] Then, based on Figure 9 、 Figure 10 A fourth modification example will be described.

[0138] Figure 9 This is a plan view of the base plate portion 7 according to the fourth modified example as viewed from the end plate portion 8 side. Figure 9 With the aforementioned Figure 2 correspond. Figure 10 This is a plan view of the end plate portion 8 according to the fourth modification as viewed from the base plate portion 7 side. Figure 10 With the aforementioned Figure 3 correspond.

[0139] For example, you can also Figure 9 、 Figure 10 As shown, the reduction gear 1 is an eccentric oscillating type reduction gear including four crankshafts (not shown).

[0140] In this case, four crankshaft insertion recesses 7e are formed in the base plate portion 7 around the base plate shaft insertion hole 7d. Four pillars 9 are formed protruding from the base plate portion 7, one located between circumferentially adjacent crankshaft insertion recesses 7e. Four base plate protrusions 51 are formed radially outward of each crankshaft insertion recess 7e and between circumferentially adjacent pillars 9. The base plate protrusions 51 are formed along the outer circumferential edge of the end surface 7f of the base plate portion 7.

[0141] The end plate portion 8 has crankshaft insertion holes 8e formed coaxially with the crankshaft insertion recesses 7e of the base plate portion 7. The end surface 8f of the end plate portion 8 has four seating surfaces 61 and four end plate projections 62 formed at locations axially opposed to the column portion 9.

[0142] Even in the case of such a configuration, the same effects as those of the aforementioned embodiment can be achieved.

[0143] [Fifth Modification]

[0144] Then, based on Figure 11 A fifth modification example will be described.

[0145] Figure 11 This is a plan view of the base plate portion 7 according to the fifth modification example as viewed from the end plate portion 8 side. Figure 11 With the aforementioned Figure 2 correspond.

[0146] In the above embodiment, the inner peripheral surface 51 a of the substrate protrusion 51 is located on the radially outermost imaginary circle C of the column portion 9 centered on the first rotation axis A1 or radially outward of the imaginary circle C.

[0147] However, it is not limited to this, and can also be Figure 11 As shown, the base plate protrusion 51 is formed with a protrusion 51 d that protrudes radially inward.

[0148] The protrusion 51d is disposed between circumferentially adjacent columnar portions 9. The protrusion 51d extends along the periphery of the crankshaft insertion recess 7e. However, the present invention is not limited thereto, and the protrusion 51d may not extend along the periphery of the crankshaft insertion recess 7e.

[0149] Even with this configuration, the base plate protrusions 51 and the end plate protrusions 62 can restrict axial movement of the externally toothed gears 15 and 16. A gap G1 can be maintained between the end face 15e of the first externally toothed gear 15 and the end face 7f of the base plate portion 7, and a gap G2 can be maintained between the end face 16e of the second externally toothed gear 16 and the end face 8f of the end plate portion 8. Consequently, lubricant can be fully distributed throughout the reduction gear 1, reliably improving the driving efficiency of the reduction gear 1. The protrusions 51 and 62 minimize the wobbling and rattling of the externally toothed gears 15 and 16.

[0150] [Other Modifications]

[0151] The present invention is not limited to the above-described embodiment, and includes embodiments in which various modifications are added to the above-described embodiment without departing from the spirit of the present invention.

[0152] For example, in the above embodiment, so-called angular contact ball bearings, i.e., main bearings 41 and 42, are provided to rotatably support the gear carrier 3 relative to the housing 2. However, this is not limiting, and various bearings can be used as the main bearings 41 and 42. For example, in addition to rolling bearings, sliding bearings can also be used.

[0153] In the above embodiment, the outer ring 43 of the first main bearing 41 is described as being fitted with the first housing bearing retaining surface 22a, and the inner ring 44 is fitted with the base plate bearing retaining surface 7c. The outer ring 43 of the second main bearing 42 is described as being fitted with the second housing bearing retaining surface 22b, and the inner ring 44 is fitted with the end plate bearing retaining surface 8c. However, this is not limiting. The outer rings 43 of each main bearing 41 or 42 may be integral with the housing 2. In this case, the outer rings 43 may be cast into the bearing retaining surfaces 22a or 22b, respectively. The inner rings 44 of each main bearing 41 or 42 may be integral with the corresponding base plate 7 or end plate 8, respectively. In this case, the inner rings 44 may be cast into the bearing retaining surfaces 7c or 8c, respectively.

[0154] In the above embodiment, the case where the housing 2, base plate 7, and end plate 8 are each formed of ductile iron has been described. For example, FCD450 has been used as the ductile iron. However, this is not limiting, and a variety of materials can be used for the housing 2, base plate 7, and end plate 8.

[0155] In the above embodiment, the reduction mechanism 4 is described as having two externally toothed gears 15 and 16. However, this is not limiting; the reduction mechanism 4 only needs to have at least one externally toothed gear. If there is only one externally toothed gear, the base plate protrusion 51 and the end plate protrusion 62 can each abut against both surfaces of the externally toothed gear.

[0156] In the above embodiment, the crankshaft insertion recess 7e for rotatably supporting the shaft body 13c of the crankshaft 13 is formed in the base plate 7. However, the present invention is not limited thereto, and the crankshaft insertion recess 7e may be a hole.

[0157] In the above-mentioned embodiment, the case where the substrate protrusion 51 is formed along the outer peripheral edge of the end face 7f of the substrate portion 7 is described. The case where the end plate protrusion 62 is formed along the outer peripheral edge of the end face 8f of the end plate portion 8 is described. However, this is not limited to this, and the substrate protrusion 51 may not be formed completely along the outer peripheral edge of the end face 7f of the substrate portion 7. The end plate protrusion 62 may not be formed completely along the outer peripheral edge of the end face 8f of the end plate portion 8. However, the substrate protrusion 51 is preferably formed on the outer peripheral portion of the end face 7f of the substrate portion 7. The end plate protrusion 62 is preferably formed on the outer peripheral portion of the end face 8f of the end plate portion 8. By configuring in this way, the same effect as that of the above-mentioned embodiment is achieved.

[0158] In the above-described embodiment, the case where the end plate protrusion 62 and the substrate protrusion 51 are arranged so as to be staggered in the circumferential direction when viewed from the axial direction has been described. In other words, the case where the end plate protrusion 62 and the substrate protrusion 51 are arranged so as to be staggered in the axial direction has been described. The staggered arrangement mentioned here includes either a case where the end plate protrusion 62 and the substrate protrusion 51 are slightly staggered in the circumferential direction when viewed from the axial direction, or a case where they are completely staggered. In other words, the case includes either a case where a portion of the end plate protrusion 62 and the substrate protrusion 51 overlap in the axial direction, or a case where there is no overlapping portion between the end plate protrusion 62 and the substrate protrusion 51.

[0159] In the embodiments disclosed in this specification, components composed of multiple objects may be integrated into one object, or conversely, components composed of one object may be divided into multiple objects. Regardless of whether they are integrated or not, the components may be constructed so as to achieve the purpose of the invention.

Claims

1. A gear device, wherein: The gear unit has: a cylindrical housing having an internally toothed gear; a first gear carrier disposed radially inward of the housing and rotatably supported by the housing via a first bearing; a second gear carrier disposed radially inward of the housing and opposed to the first gear carrier in the axial direction of the housing, and rotatably supported by the housing via a second bearing; at least one crankshaft rotatably supported by the first carrier and the second carrier, to which an external rotational force is input; as well as at least one external gear disposed between the first gear frame and the second gear frame and meshing with the internal gear. The crankshaft has: a shaft body; and an eccentric portion provided on the shaft body and eccentric relative to the rotation axis of the shaft body, The externally toothed gear is rotatably supported by the eccentric portion. The first carrier includes a first protrusion that abuts against an end surface of the externally toothed gear on the first carrier side. The second carrier includes a second protrusion that contacts an end surface of the externally toothed gear on the second carrier side.

2. The gear device according to claim 1, wherein: The first bearing and the second bearing include: an outer ring, which is provided on the housing; an inner ring disposed radially inward of the outer ring and provided on the corresponding first gear carrier or the second gear carrier; and A plurality of rolling elements are arranged between the outer ring and the inner ring, The first protrusion protrudes to a position closer to the external gear than the inner ring of the first bearing. The second protrusion protrudes to a position closer to the external gear than the inner ring of the second bearing.

3. The gear device according to claim 1 or 2, wherein: There are a plurality of the first convex portion and the second convex portion, The plurality of first protrusions and the plurality of second protrusions are arranged so as to be offset from each other in the circumferential direction when viewed from the axial direction.

4. The gear device according to claim 3, wherein: The first protrusion is provided on an outer peripheral portion of a surface of the first gear carrier that faces the external gear in the axial direction. The second protrusion is provided on an outer peripheral portion of a surface of the second carrier that faces the externally toothed gear in the axial direction.

5. The gear device according to claim 4, wherein: The first gear frame includes a plurality of columns, which protrude toward the second gear frame and are used to maintain a constant interval between the first gear frame and the second gear frame. The first protrusion is provided at least radially outward of the column portion.

6. The gear device according to claim 5, wherein: The second gear rack has a base surface for the front end of the column portion to abut against. The front end surface of the second protrusion and the base surface are arranged on the same plane.

7. The gear device according to claim 1, wherein: The internal gear includes a plurality of internal tooth pins provided on the inner peripheral surface of the housing and arranged at equal intervals in the circumferential direction. Part of the axial end surface of the internal gear pin abuts against the first bearing and the second bearing.

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