Gear device

Abstract

To provide a gear device capable of securely improving drive efficiency.SOLUTION: A reduction gear 1 comprises: a cylindrical case 2 having internal teeth pins 5; a base plate part 7 rotatably supported in the case 2 via a first main bearing 41; an end plate part 8 rotatably supported in the case 2 via a second main bearing 42; a crankshaft 13 rotatably supported by the base plate part 7 and the end plate part 8, to which external rotational force is input; and oscillating external gear wheels 15 and 16 disposed between the base plate part 7 and the end plate part 8 and meshing with the internal teeth pins 5. A base plate projection 51 is provided on the base plate part 7 to abut on an end face 15e of the first oscillating external gear wheel 15, and an end plate projection 62 is provided on the end plate part 8 to abut on an end face 16e of the second oscillating external gear wheel 16.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A so-called eccentric oscillating reduction gear has been known as a gear device. This reduction gear includes an internal gear, two carriers rotatably supported by the internal gear via bearings and arranged opposite each other in the direction of the rotation axis, a crankshaft rotatably supported by the carriers and having an eccentric portion, and an oscillating external gear arranged between the carriers, rotatably supported by the crankshafts, and meshed with the internal gear.

[0003] In order to improve the drive efficiency of such gear devices, various techniques have been proposed for spreading lubricant throughout the gear device while restricting the axial movement of the oscillating external gear. For example, a technique has been disclosed in which one of the two carriers is provided with a protrusion that abuts against the axial end face of the oscillating external gear (see, for example, Patent Document 1). The convex portions may be formed around the entire circumference or may be scattered intermittently in the circumferential direction. By configuring it in this way, the convex portions can restrict axial movement of the oscillating external gear. Furthermore, a gap corresponding to the size of the convex portions can be secured between the oscillating external gear and the carrier. Lubricant can be distributed throughout the gear device via this gap. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-124730 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, there are points where the bearing and the oscillating external gear butt against each other, which obstructs the flow of lubricant, making it difficult to ensure that the lubricant is distributed throughout the gear device, making it difficult to reliably improve the drive efficiency of the gear device.

[0006] The present invention provides a gear device that can reliably improve driving efficiency. [Means for solving the problem]

[0007] A gear device according to one embodiment of the present invention comprises a cylindrical case having an internal gear, a first carrier arranged radially inside the case and rotatably supported on the case via a first bearing, a second carrier arranged radially inside the case and opposite the first carrier in the axial direction of the case and rotatably supported on the case via a second bearing, at least one crankshaft rotatably supported on the first carrier and the second carrier and to which an external rotational force is input, and at least one oscillating external gear arranged between the first carrier and the second carrier and meshed with the internal gear, wherein the crankshaft has a shaft main body and an eccentric portion provided on the shaft main body and eccentric with respect to the rotation axis of the shaft main body, and the oscillating external gear is rotatably supported on the eccentric portion, and the first carrier is provided with a first convex portion that abuts on the end face of the oscillating external gear on the first carrier side.

[0008] With this configuration, the first convex portion and the second convex portion can restrict axial movement of the oscillating external gear. The first convex portion can ensure a gap between the oscillating external gear and the first carrier. The second convex portion can ensure a gap between the oscillating external gear and the second carrier. In this way, gaps can be secured on both sides of the axial direction of the oscillating external gear. Therefore, it is possible to restrict axial movement of the oscillating external gear while ensuring sufficient distribution of lubricant throughout the gear device. This reliably improves the drive efficiency of the gear device.

[0009] In the above configuration, the first bearing and the second bearing may comprise an outer race provided in the case, an inner race arranged radially inside the outer race and provided in the corresponding first carrier or second carrier, and a plurality of rolling elements arranged between the outer race and the inner race, and the first convex portion may protrude toward the oscillating external gear more than the inner race of the first bearing, and the second convex portion may protrude toward the oscillating external gear more than the inner race of the second bearing.

[0010] In the above configuration, the first convex portion and the second convex portion may be provided in plurality, and the plurality of first convex portions and the plurality of second convex portions may be arranged offset from each other in the circumferential direction when viewed from the axial direction.

[0011] In the above configuration, the first convex portion may be provided on the outer circumferential portion of a surface of the first carrier that faces the oscillating external gear in the axial direction, and the second convex portion may be provided on the outer circumferential portion of a surface of the second carrier that faces the oscillating external gear in the axial direction.

[0012] In the above configuration, the first carrier may have a plurality of pillar portions protruding toward the second carrier to maintain a constant distance between the first carrier and the second carrier, and the first convex portions may be provided at least radially outward of the pillar portions.

[0013] In the above configuration, the second carrier may have a seat surface against which the tip of the column portion abuts, and a tip surface of the second protrusion may be disposed on the same plane as the seat surface.

[0014] In the above configuration, the internal gear includes a plurality of internal pins provided on the inner surface of the case and arranged at equal intervals in the circumferential direction, and a portion of the axial end face of the internal pins may abut against the first bearing and the second bearing. [Effects of the Invention]

[0015] The above-described gear device can reliably improve driving efficiency. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a reduction gear transmission according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the base plate portion seen from the end plate portion side in the embodiment of the present invention. [Figure 3] FIG. 2 is a plan view of the end plate portion in the embodiment of the present invention, viewed from the base plate portion side. [Figure 4] FIG. 10 is a plan view of a base plate portion according to a first modified example of the embodiment of the present invention, viewed from the end plate portion side. [Figure 5] FIG. 10 is a plan view of an end plate portion in a first modified example of the embodiment of the present invention, viewed from the base plate portion side. [Figure 6] FIG. 10 is a plan view of an end plate portion in a second modified example of the embodiment of the present invention, viewed from the base plate portion side. [Figure 7] FIG. 11 is a plan view of a substrate portion according to a third modified example of the embodiment of the present invention, viewed from the end plate portion side. [Figure 8] FIG. 11 is a plan view of an end plate portion in a third modified example of the embodiment of the present invention, viewed from the base plate portion side. [Figure 9] FIG. 10 is a plan view of a substrate portion according to a fourth modified example of the embodiment of the present invention, viewed from the end plate portion side. [Figure 10] FIG. 11 is a plan view of an end plate portion in a fourth modified example of the embodiment of the present invention, viewed from the base plate portion side. [Figure 11] FIG. 11 is a plan view of a substrate portion according to a fifth modified example of the embodiment of the present invention, viewed from the end plate portion side. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, an embodiment of the present invention will be described with reference to the drawings.

[0018] <Deceleration device> FIG. 1 is a cross-sectional view of a reduction gear device 1, which is a gear device. As shown in Fig. 1, the reduction gear 1 reduces the rotation speed of, for example, an electric motor (not shown) and outputs the reduced speed. The reduction gear 1 is a so-called eccentric oscillating reduction gear. The reduction gear 1 includes a cylindrical case 2, a carrier 3 rotatably provided radially inside the case 2, and a reduction mechanism 4 connected to the carrier 3. The central axis of the case 2 and the rotation axis of the carrier 3 coincide with each other. In the following description, the central axis and the rotation axis will be commonly referred to as the first rotation axis A1. The direction parallel to the first rotation axis A1 will be referred to as the axial direction. The rotation direction of the carrier 3 will be referred to as the circumferential direction. The radial direction of the case 2, which is perpendicular to the axial and circumferential directions, will be simply referred to as the radial direction.

[0019] <Case> The case 2 is made of, for example, spheroidal graphite cast iron (ductile cast iron). For example, FCD450 is used as the spheroidal graphite cast iron. An outer flange portion 2a that protrudes radially outward is integrally formed on the outer peripheral surface of the case 2. A plurality of 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 the bolt holes 2b and tightened to, for example, the arm of an industrial robot to secure the reduction gear device 1.

[0020] A plurality of pin grooves 2c are formed in the inner peripheral surface 2d of the case 2 along the axial direction. The pin grooves 2c are arranged at equal intervals in the circumferential direction. An internally toothed pin 5 is fitted into each pin groove 2c. The internally toothed pin 5 functions as an internal tooth that meshes with oscillating external gears 15 and 16 of the reduction mechanism 4, which will be described later.

[0021] On the inner peripheral surface 2d of the case 2, case bearing retaining surfaces 22a, 22b (first case bearing retaining surface 22a, second case bearing retaining surface 22b) are formed on both axial sides of the pin groove 2c via step surfaces 21a, 21b (first step surface 21a, second step surface 21b), respectively. Each of the case bearing retaining surfaces 22a, 22b is formed in an annular shape radially outward from the pin groove 2c. Of the two case bearing retaining surfaces 22a, 22b, the first case bearing retaining surface 22a is provided with a first main bearing 41. Of the two case bearing retaining surfaces 22a, 22b, the second case bearing retaining surface 22b is provided with a second main bearing 42.

[0022] The main bearings 41, 42 have the same configuration and are arranged symmetrically about the axial center of the case 2. For this reason, in the following explanation, only the first main bearing 41 will be explained, and the second main bearing 42 will be given the same reference numeral as the first main bearing 41 and will not be explained in detail.

[0023] The first main bearing 41 is a so-called angular contact ball bearing. The first main bearing 41 includes an annular outer race 43 fitted to the first case bearing retaining surface 22a, an annular inner race 44 arranged radially inward of the outer race 43, a plurality of rolling elements 45 arranged between the outer race 43 and the inner race 44, and a cage 46 that retains the plurality of rolling elements 45 at equal intervals in the circumferential direction.

[0024] The outer race 43 of each main bearing 41, 42 is located closer to the center of the case 2 in the axial direction than the inner race 44. The outer races 43 have opposing end faces 43a that abut against the corresponding stepped surfaces 21a, 21b. This positions each main bearing 41, 42 in the axial direction relative to the case 2.

[0025] The end face 43a of the outer race 43 of each main bearing 41, 42 protrudes slightly radially inward beyond the pin groove 2c. A part of the axial end of the internally toothed pin 5 abuts against this protruding inner diameter end 43b of the outer race 43. This positions the internally toothed pin 5 in the axial direction. The carrier 3 is rotatably supported on the case 2 via the main bearings 41 and 42.

[0026] <Career> The carrier 3 includes a disk-shaped base plate portion (an example of a first carrier in the claims) 7 and an end plate portion (an example of a second carrier in the claims) 8, which are arranged axially opposite each other. The base plate portion 7 and the end plate portion 8 are made of, for example, spheroidal graphite cast iron (ductile cast iron). For example, FCD450 is used as the spheroidal graphite cast iron.

[0027] <Board> FIG. 2 is a plan view of the base plate portion 7 as seen from the end plate portion 8 side. 1 and 2, the base plate portion 7 is formed in a disk shape. A base plate bearing holding surface 7c is formed on the outer peripheral surface 7a of the base plate portion 7 at a location facing the first case bearing holding surface 22a in the radial direction. The base plate bearing holding surface 7c is formed in an annular shape radially inward from the outer peripheral surface 7a via a step portion 7b.

[0028] An inner race 44 of the first main bearing 41 is fitted onto the base plate bearing holding surface 7c. An axial end of the inner race 44 of the first main bearing 41 abuts against the stepped portion 7b. This positions the first main bearing 41 in the axial direction relative to the base plate 7. When this positioning is achieved, an end face 44a of the inner race 44 of the first main bearing 41 on the end plate 8 side and an end face 7f of the base plate 7 on the end plate 8 side are located on the same plane.

[0029] A seal portion 24 is provided between the outer peripheral surface 7a of the base plate portion 7 and the inner peripheral surface 2d of the case 2, on the opposite side of the first main bearing 41 from the end plate portion 8. The seal portion 24 ensures sealing between the base plate portion 7 and the case 2.

[0030] A base plate shaft insertion hole 7d is formed in the radial center of the base plate portion 7. A plurality of crank insertion recesses 7e (for example, three in this embodiment) are formed around the base plate shaft insertion hole 7d in the base plate portion 7. Each crank insertion recess 7e is formed on an end face 7f of the base plate portion 7. The crank insertion recesses 7e are arranged at equal intervals in the circumferential direction. A crank bearing 18 is provided in each crank insertion recess 7e. The crank bearing 18 is, for example, a tapered roller bearing.

[0031] Three pillar portions 9 are formed on the end surface 7f of the base plate portion 7 so as to protrude toward the end plate portion 8. The pillar portions 9 are formed in a triangular prism shape so that the circumferential width gradually increases toward the radially outer side as viewed from the axial direction. Each pillar portion 9 is disposed between adjacent crank insertion recesses 7e in the circumferential direction. The three pillar portions 9 are disposed at equal intervals in the circumferential direction.

[0032] Two female screw portions 26 are formed on the tip surface 9a of each column portion 9. The two female screw portions 26 are arranged side by side in the circumferential direction. A post pin hole 27 is formed on the tip surface 9a of each column portion 9, radially inward from the two female screw portions 26. These female screw portions 26 and post pin holes 27 are used to integrate the base plate portion 7 and the end plate portion 8 (details will be described later).

[0033] A plurality of (for example, three in this embodiment) substrate protrusions (an example of first protrusions in the claims) 51 are formed on the outer periphery of the end surface 7f of the substrate part 7. In Fig. 2, the substrate protrusions 51 are shown shaded to clearly show the shape of the substrate protrusions 51 (the same applies to the following modified examples). The end face 7f of the base plate portion 7 is located on the same plane as the end face 44a of the inner race 44 of the first main bearing 41. Therefore, the base plate protrusion 51 protrudes toward the end plate portion 8 beyond the inner race 44. The protruding height of the base plate protrusion 51 is sufficiently smaller than the protruding height of the pillar portion 9.

[0034] Three base plate protrusions 51 are formed radially outside each crank insertion recess 7e and between adjacent pillar portions 9 in the circumferential direction. The base plate protrusions 51 are formed along the outer peripheral edge of the end face 7f of the base plate portion 7. In other words, the base plate protrusions 51 are formed in an arc shape centered on the first rotation axis A1 when viewed in the axial direction.

[0035] A crank insertion recess 7e is disposed at the circumferential center of each base plate protrusion 51. The positional relationship between the crank insertion recess 7e and each base plate protrusion 51 is such that the periphery of the crank insertion recess 7e is located slightly radially outward of the inner circumferential surface 51a on the radially inner side of the base plate protrusion 51. The position of the inner circumferential surface 51a of the base plate protrusion 51 is located on an imaginary circle C centered on the first rotation axis A1 and passing through the radially outermost part of the column portion 9, or radially outward of the imaginary circle C. Rounded chamfered portions 51b are formed on both circumferential ends of the base plate protrusion 51. The rounded chamfered portions 51b are formed in an arc shape when viewed in the axial direction. Such a base plate protrusion 51 restricts the axial movement of the first oscillating external gear 15 (described in detail later).

[0036] <End plate> FIG. 3 is a plan view of the end plate portion 8 as seen from the base plate portion 7 side. 1 and 3, the end plate portion 8 is formed in a disk 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 facing the second case bearing retaining surface 22b in the radial direction. The end plate bearing retaining surface 8c is formed in an annular shape radially inward from the outer peripheral surface 8a via a stepped portion 8b.

[0037] An inner race 44 of the second main bearing 42 is fitted onto the end plate bearing retaining surface 8c. An axial end of the inner race 44 of the second main bearing 42 abuts against the stepped portion 8b. This positions the second main bearing 42 in the axial direction relative to the end plate 8. When this positioning is achieved, an end face 44a of the inner race 44 of the second main bearing 42 facing the base plate 7 and an end face 8f of the end plate 8 facing the base plate 7 are located on the same plane.

[0038] 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. A plurality of crank insertion holes 8e (for example, three in this embodiment) are formed around the end plate shaft insertion hole 8d in the end plate portion 8. The crank insertion holes 8e are arranged at equal intervals in the circumferential direction. Each crank insertion hole 8e is arranged coaxially with the crank insertion recess 7e of the base plate portion 7. That is, the central axes A2 of the crank insertion hole 8e and the crank insertion recess 7e, which are opposed in the axial direction, are parallel to the first rotation axis A1. A crank bearing 18 is provided in each crank insertion hole 8e, similar to the crank insertion recess 7e.

[0039] Three seating surfaces 61 are formed on the end face 8f of the end plate portion 8 at locations facing the column portion 9 in the axial direction, and three end plate protrusions (an example of the second protrusions in the claims) 62 are formed radially outward of the seating surfaces 61. In Fig. 3, the seating surfaces 61 and the end plate protrusions 62 are shown shaded to clearly show the shapes of the seating surfaces 61 and the end plate protrusions 62 (the same applies to the following modified examples). An end face 8f of the end plate portion 8 is located on the same plane as an end face 44a of the inner race 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 race 44.

[0040] The tip end surface 9a of the column portion 9 abuts against the seat surface 61. The seat surface 61 is formed to correspond to the shape of the column portion 9. That is, the seat surface 61 is formed in the shape of a triangular prism so that the circumferential width gradually increases toward the radially outer side when viewed from the axial direction.

[0041] Two bolt insertion holes 63 are formed in each base surface 61. The two bolt insertion holes 63 are aligned in the circumferential direction and are arranged coaxially with the female thread portion 26 of the column portion 9. Bolts 91 are inserted into the two bolt insertion holes 63 from the side opposite the base plate portion 7, and each bolt 91 is tightened into the female thread portion 26. This fixes the end plate portion 8 to the base plate portion 7. A space having a width equal to the height of the column portion 9 is formed between the base plate portion 7 and the column portion 9.

[0042] An end plate pin hole 64 is formed in each base surface 61 radially inward of the bolt insertion hole 63. The end plate pin hole 64 is arranged coaxially with the column pin hole 27. By inserting or press-fitting a pin 92 into these pin holes 27, 63, the base plate portion 7 and the end plate portion 8 are positioned with high precision.

[0043] The end plate protrusion 62 is formed along the outer periphery of the base surface 61 and the outer periphery of the end face 8f of the end plate portion 8. In other words, the end plate protrusion 62 is formed in an arc shape centered on the first rotation axis A1 when viewed in the axial direction. Because the end plate protrusion 62 is formed on the outer periphery of the base surface 61, the end plate protrusion 62 and the base plate protrusion 51 are arranged offset from each other in the circumferential direction when viewed in the axial direction. In other words, the end plate protrusion 62 and the base plate protrusion 51 are arranged alternately when viewed in the axial direction. Rounded chamfered portions 62a are formed on both circumferential ends of the end plate protrusion 62. The rounded chamfered portions 62a are formed in an arc shape when viewed in the axial direction. A tip end surface 62b of such an end plate protrusion 62 is arranged on the same plane as the seat surface 61. The end plate protrusion 62 restricts the axial movement of the second oscillating external gear 16 (described in detail later).

[0044] <Deceleration mechanism> 1, the speed reduction mechanism 4 reduces the rotation of the electric motor (not shown) at a fixed ratio to rotate the carrier 3. The speed reduction mechanism 4 includes three crankshafts 13 inserted into the crank insertion recesses 7e of the base plate 7 and the crank insertion holes 8e of the end plate 8, a transmission spur gear 14 provided at the axial end of each crankshaft 13, and two oscillating external gears 15, 16 (a first oscillating external gear 15 and a second oscillating external gear 16) provided between the base plate 7 and the end plate 8.

[0045] External teeth 17 are formed on the outer periphery of the transmission spur gear 14. The external teeth 17 are meshed with, for example, a motor shaft of an electric motor (not shown), causing the transmission spur gear 14 to rotate.

[0046] The crankshaft 13 is rotatably supported by the carrier 3 (the base plate 7 and the end plate 8) via crank bearings 18. The crankshaft 13 has a shaft body 13c that rotates about a 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. Both axial ends of the shaft body 13c are rotatably supported by the carrier 3 (the base plate 7 and the end plate 8) via crank bearings 18. 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 a central axis A2. Hereinafter, the central axis A2 will be referred to as the second rotation axis A2 of the crankshaft 13.

[0047] The first eccentric portion 13a and the second eccentric portion 13b are eccentric from the second rotation axis A2. The first eccentric portion 13a and the second eccentric portion 13b are disposed adjacent to each other in the axial direction between the two crank bearings 18. In other words, the first eccentric portion 13a and the second eccentric portion 13b are disposed adjacent to each other in the axial direction between the base plate portion 7 and the end plate portion 8. The first eccentric portion 13a and the second eccentric portion 13b are disposed with a phase angle shift of 180°. The inner peripheral surface of each of the eccentric portions 13a, 13b is fitted with a roller bearing 19. The roller bearing 19 is, for example, a cylindrical roller bearing. The first oscillating external gear 15 and the second oscillating external gear 16 are rotatably supported on each of the crankshafts 13 via the roller bearings 19.

[0048] The first oscillating external gear 15 and the second oscillating external gear 16 are disposed in the space between the base plate portion 7 and the end plate portion 8. The first oscillating external gear 15 and the second oscillating external gear 16 overlap in the axial direction. Through holes 15a, 16a are formed in the first oscillating external gear 15 and the second oscillating external gear 16. The outer peripheral surfaces of roller bearings 19 are fitted into the through holes 15a, 16a, respectively. As a result, when the first eccentric portion 13a and the second eccentric portion 13b are oscillatingly rotated by the rotation of the crankshaft 13, the first oscillating external gear 15 and the second oscillating external gear 16 are oscillatingly rotated via the roller bearings 19.

[0049] The first oscillating external gear 15 and the second oscillating external gear 16 are respectively formed with openings 15b, 16b to avoid interference with the column portion 9. Shaft insertion holes 15c, 16c are formed in the radial centers of the first oscillating external gear 15 and the second oscillating external gear 16. External teeth 15d, 16d are formed on the outer periphery of the first oscillating external gear 15 and the outer periphery of the second oscillating external gear 16, respectively. The number of teeth of each of the external teeth 15d, 16d is, for example, one less than the number of internal tooth pins 5 of the case 2.

[0050] The tip end surface 51c of the base plate protrusion 51 abuts against the outer periphery of the end surface 15e of the first oscillating external gear 15 on the base plate portion 7 side. Therefore, a gap G1 is formed between the end surface 15e of the first oscillating external gear 15 and the end surface 7f of the base plate portion 7. The tip end surface 62b of the end plate protrusion 62 abuts against the outer periphery of the end surface 16e of the second oscillating external gear 16 on the end plate portion 8 side. Therefore, a gap G2 is formed between the end surface 16e of the second oscillating external gear 16 and the end surface 8f of the end plate portion 8.

[0051] <Method of manufacturing the base plate portion and the end plate portion> Next, a method for manufacturing the base plate portion 7 and the end plate portion 8 will be described. The base plate 7 and the end plate 8 are formed by casting. That is, the base plate 7 and the end plate 8 are formed by pouring, for example, molten FCD450 into a sand mold (not shown). Thereafter, in the substrate portion 7, the substrate bearing holding surface 7c, the tip surface 9a of the column portion 9, the tip surface 51c of the substrate protrusion 51, etc. are cut using, for example, a lathe (not shown). Here, the position of the inner peripheral surface 51a of the substrate protrusion 51 is on an imaginary circle C that passes through the radially outermost part of the column portion 9 and is centered on the first rotation axis A1, or is located radially outward of the imaginary circle C. Therefore, the column portion 9 does not get in the way when the substrate protrusion 51 is cut using the lathe.

[0052] In the end plate 8, the end plate bearing retaining surface 8c, the seat surface 61, the tip surface 62b of the end plate protrusion 62, and the like are cut using, for example, a lathe (not shown). Here, the tip surface 62b of the end plate protrusion 62 is disposed on the same plane as the seat surface 61. Therefore, the end plate protrusion 62 and the seat surface 61 can be machined simultaneously. In this way, the manufacturing of the base plate portion 7 and the end plate portion 8 is completed.

[0053] <Operation of the reduction gear device and the action of the base plate protrusions and end plate protrusions> Next, the operation of the reduction gear transmission 1 and the functions of the base plate protrusions 51 and the end plate protrusions 62 will be described. First, the operation of the reduction gear 1 will be described. The reduction gear 1 (inside the case 2 and inside the carrier 3) is filled with a lubricant (not shown). In the reduction gear 1, a portion of the external teeth 15d, 16d of each of the oscillating external gears 15, 16 meshes with the internal tooth pin 5 of the case 2. In this state, for example, when the rotation of an electric motor (not shown) is transmitted to each crankshaft 13 via the transmission spur gear 14, these crankshafts 13 rotate about the second rotation axis A2.

[0054] As a result, each of the oscillating external gears 15, 16 is oscillated and rotated. Here, the number of teeth of each of the external teeth 15d, 16d is, for example, one less than the number of the internal pins 5. Therefore, each of the oscillating external gears 15, 16 is rotated on its axis such that the meshing points of each of the external teeth 15d, 16d with respect to the internal pin 5 (case 2) are sequentially shifted in the circumferential direction. This rotation is decelerated relative to the rotation of the crankshaft 13.

[0055] As each of the oscillating external gears 15, 16 rotates, each of the crankshafts 13 also revolves around the first rotation axis A1 while rotating about the second rotation axis A2. Each of the crankshafts 13 is rotatably supported by the carrier 3 (base plate portion 7, end plate portion 8). Therefore, the carrier 3 rotates as each of the crankshafts 13 revolves. As a result, the reduction gear 1 reduces the rotation of, for example, an electric motor (not shown) and outputs the reduced rotation. If the carrier 3 is fixed to the arm of an industrial robot or the like, the reduction gear 1 can reduce the rotation of, for example, an electric motor (not shown) and output it from the case 2. On the other hand, if the case 2 is fixed to the arm of an industrial robot or the like, the reduction gear 1 can reduce the rotation of, for example, an electric motor (not shown) and output it from the carrier 3.

[0056] Next, the functions of the base plate protrusion 51 and the end plate protrusion 62 will be described. The tip end surface 51c of the base plate protrusion 51 abuts against the end surface 15e of the first oscillating external gear 15 on the base plate portion 7 side. Therefore, the base plate protrusion 51 restricts the movement of the first oscillating external gear 15 in the axial direction toward the base plate portion 7 side. The tip end surface 62b of the end plate protrusion 62 abuts against the end surface 16e of the second oscillating external gear 16 on the end plate portion 8 side. Therefore, the end plate protrusion 62 restricts the movement of the second oscillating external gear 16 toward the end plate portion 8 in the axial direction. Moreover, the oscillating external gears 15 and 16 overlap each other in the axial direction.

[0057] Therefore, according to the reduction gear transmission 1 described above, the base plate protrusions 51 and the end plate protrusions 62 can restrict the axial movement of each of the oscillating external gears 15, 16. In addition, the base plate protrusion 51 ensures a gap G1 between the end face 15e of the first oscillating external gear 15 and the end face 7f of the base plate portion 7. The end plate protrusion 62 ensures a gap G2 between the end face 16e of the second oscillating external gear 16 and the end face 8f of the end plate portion 8. In this way, gaps G1 and G2 can be ensured on both sides of the oscillating external gears 15 and 16 in the axial direction. This allows the lubricant to be sufficiently distributed throughout the reduction gear 1, thereby reliably improving the drive efficiency of the reduction gear 1.

[0058] Each of the main bearings 41, 42, which rotatably support the carrier 3 relative to the case 2, includes an outer race 43, an inner race 44, and a plurality of rolling elements 45. The base plate protrusion 51 protrudes further toward the end plate 8 than the inner race 44 of the first main bearing 41. The end plate protrusion 62 protrudes further toward the base plate 7 than the inner race 44 of the second main bearing 42. Therefore, the base plate protrusion 51 can reliably ensure a gap between the first oscillating external gear 15 and the first main bearing 41. The end plate protrusion 62 can reliably ensure a gap between the second oscillating external gear 16 and the second main bearing 42. This makes it easier for lubricant to flow into each of the main bearings 41, 42, further improving the drive efficiency of the reduction gear transmission 1.

[0059] When viewed from the axial direction, the end plate protrusions 62 and the base plate protrusions 51 are arranged alternately in the circumferential direction. This ensures that the gaps G1, G2 between the oscillating external gears 15, 16 and the carrier 3 (base plate portion 7, end plate portion 8) are well balanced in the circumferential direction. This makes it easier to spread the lubricant throughout the reduction gear 1.

[0060] The base plate protrusion 51 is formed along the outer peripheral edge of the end face 7f of the base plate portion 7. The end plate protrusion 62 is formed along the outer peripheral edge of the end face 8f of the end plate portion 8. With this configuration, each protrusion 51, 62 can abut the corresponding oscillating external gears 15, 16 as far radially outward (closer to the outer periphery) as possible. This makes it possible to suppress runout of each oscillating external gear 15, 16 as much as possible, and to suppress rattle of each oscillating external gear 15, 16 as much as possible. This further improves the drive efficiency of the reduction gear device 1.

[0061] The position of the inner peripheral surface 51a of the substrate protrusion 51 is on an imaginary circle C that passes through the radially outermost portion of the column portion 9 and is centered on the first rotation axis A1, or is located radially outward of the imaginary circle C. Therefore, when cutting the substrate protrusion 51 using a lathe, the column portion 9 does not get in the way. In other words, it is possible to cut the tip surface 51c of the substrate protrusion 51 while avoiding the column portion 9. This improves the processability of the substrate portion 7.

[0062] The tip surface 62b of the end plate protrusion 62 is disposed on the same plane as the seat surface 61. Therefore, the end plate protrusion 62 and the seat surface 61 can be machined simultaneously, thereby improving the workability of the end plate portion 8.

[0063] The end face 43a of the outer race 43 in each of the main bearings 41 and 42 protrudes slightly radially inward beyond the pin groove 2c. A part of the axial end of the internal pin 5 abuts against this protruding inner diameter end 43b of the outer race 43. Therefore, the internal pin 5 can be positioned in the axial direction by each of the main bearings 41 and 42.

[0064] By abutting only a portion of the axial end of the internally toothed pin 5 against the inner diameter end 43b of the outer race 43, the internally toothed pin 5 can be exposed as much as possible inside the case 2. This makes it easier to spread the lubricant to the internally toothed pin as well. The convex portions 51, 62 ensure gaps G1, G2 between the main bearings 41, 42 and the oscillating external gears 15, 16, respectively, which allows the lubricant to be more evenly distributed over the internal pins 5. This further improves the drive efficiency of the reduction gear transmission 1.

[0065] In the above embodiment, the reduction gear mechanism 4 has been described as having three crankshafts 13. Correspondingly, the base plate portion 7 has three pillar portions 9 protruding therefrom, and three base plate protrusions 51 have been described. The end plate portion 8 has three seat surfaces 61 and three end plate protrusions 62. However, this is not limited to this, and it is sufficient that there is at least one crankshaft 13, and that there is also at least one base plate protrusion 51 and one end plate protrusion 62. The number of crankshafts 13 and the numbers of base plate protrusions 51 and end plate protrusions 62 can be determined arbitrarily. Specific examples will be described below with reference to FIGS. 4 to 11.

[0066] [First Modification] First, the first modified example will be described with reference to FIGS. Fig. 4 is a plan view of the base plate portion 7 in the first modified example, viewed from the end plate portion 8 side. Fig. 4 corresponds to Fig. 2 described above. Fig. 5 is a plan view of the end plate portion 8 in the first modified example, viewed from the base plate portion 7 side. Fig. 5 corresponds to Fig. 3 described above. 4 and 5, for example, the reduction gear 1 may be a so-called center crank type eccentric oscillating reduction gear equipped with a single crankshaft 13 (not shown in FIGS. 4 and 5; the same applies to the following modified examples). In this case, the single crankshaft 13 is arranged coaxially with the first rotation axis A1, and the single crankshaft 13 oscillates and rotates the oscillating external gears 15, 16 (not shown in FIGS. 4 and 5; the same applies to the following modified examples).

[0067] For this reason, a crank insertion recess 7e is formed in the radial center of the base plate 7. A plurality of pillars 9 (eight in the first modified example, for example) protruding from the base plate 7 are provided around the crank insertion recess 7e. In the first modified example, the pillar portions 9 are formed in a cylindrical shape. A female screw portion 26 is formed on the tip surface 9a of each pillar portion 9. A plurality of (eight in this embodiment, for example) board protrusions 51 are formed on the outer periphery of the end surface 7f of the substrate portion 7. The board protrusions 51 are formed along the outer periphery of the end surface 7f of the substrate portion 7 and between adjacent pillar portions 9 in the circumferential direction.

[0068] A crank insertion hole 8e is formed in the radial center of the end plate portion 8. Eight seating surfaces 61 are formed on the end face 8f of the end plate portion 8 at locations facing the column portion 9 in the axial direction, and eight end plate protrusions 62 are formed on the radially outer sides of the seating surfaces 61. Even in this configuration, the same effects as those of the above-described embodiment are achieved.

[0069] [Second Modification] Next, a first modified example will be described with reference to FIG. 6 is a plan view of the end plate portion 8 in the second modified example, viewed from the side of the base plate portion 7. FIG. 6 corresponds to the above-mentioned FIG. In the above-described first modified example, eight seat surfaces 61 are formed on the end face 8f of the end plate portion 8 at locations facing the column portions 9 in the axial direction, and eight end plate protrusions 62 are formed radially outward of the seat surfaces 61. However, this is not limited to this, and the number of seat surfaces 61 and end plate protrusions 62 does not have to be the same as the number of column portions 9.

[0070] For example, as shown in Fig. 6, the number of seating surfaces 61 and end plate protrusions 62 may be four. In this case, of the eight seating surfaces 61 and eight end plate protrusions 62 shown in Fig. 5, two seating surfaces 61 and two end plate protrusions 62 adjacent in the circumferential direction are formed to be connected. That is, the seating surfaces 61 and end plate protrusions 62 in the second modified example are formed to be longer in the circumferential direction than the seating surfaces 61 and end plate protrusions 62 in the first modified example. The seating surfaces 61 and end plate protrusions 62 in the second modified example are formed in an arc shape centered on the first rotation axis A1 when viewed in the axial direction. Even in this configuration, the same effects as those of the above-described embodiment are achieved.

[0071] [Third Modification] Next, a third modified example will be described with reference to FIGS. Fig. 7 is a plan view of the base plate portion 7 in the third modified example, seen from the end plate portion 8 side. Fig. 8 corresponds to Fig. 2 described above. Fig. 8 is a plan view of the end plate portion 8 in the third modified example, seen from the base plate portion 7 side. Fig. 8 corresponds to Fig. 3 described above. As shown in FIGS. 7 and 8, for example, the reduction gear 1 may be an eccentric oscillating reduction gear including two crankshafts (not shown).

[0072] In this case, crank insertion recesses 7e are formed on both sides of the first rotation axis A1 in the base plate portion 7. Two pillar portions 9 protruding from the base plate portion 7 are provided between adjacent crank insertion recesses 7e in the circumferential direction. Two base plate protrusions 51 are formed radially outside each crank insertion recess 7e and between adjacent pillar portions 9 in the circumferential direction. The base plate protrusions 51 are formed along the outer peripheral edge of the end face 7f of the base plate portion 7.

[0073] The end plate 8 has crank insertion holes 8e formed coaxially with the crank insertion recesses 7e of the base plate 7. The end face 8f of the end plate 8 has a seat surface 61 and an end plate protrusion 62 formed at a location facing the column 9 in the axial direction. Two seat surfaces 61 and two end plate protrusions 62 are provided between adjacent crank insertion recesses 7e in the circumferential direction, on either side of the first rotation axis A1. Even in this configuration, the same effects as those of the above-described embodiment are achieved.

[0074] [Fourth Modification] Next, a fourth modified example will be described with reference to FIGS. Fig. 9 is a plan view of the base plate portion 7 in the fourth modified example, seen from the end plate portion 8 side. Fig. 9 corresponds to Fig. 2 described above. Fig. 10 is a plan view of the end plate portion 8 in the fourth modified example, seen from the base plate portion 7 side. Fig. 10 corresponds to Fig. 3 described above. As shown in FIGS. 9 and 10, for example, the reduction gear 1 may be an eccentric oscillating reduction gear including four crankshafts (not shown).

[0075] In this case, four crank insertion recesses 7e are formed around the base plate shaft insertion hole 7d in the base plate portion 7. Four pillar portions 9 protruding from the base plate portion 7 are provided between each pair of adjacent crank insertion recesses 7e in the circumferential direction. Four base plate protrusions 51 are formed radially outside each crank insertion recess 7e and between each pair of adjacent pillar portions 9 in the circumferential direction. The base plate protrusions 51 are formed along the outer peripheral edge of the end face 7f of the base plate portion 7.

[0076] The end plate 8 has crank insertion holes 8e formed coaxially with the crank insertion recesses 7e of the base plate 7. The end face 8f of the end plate 8 has seating surfaces 61 and four end plate protrusions 62 formed at locations facing the column 9 in the axial direction. Even in this configuration, the same effects as those of the above-described embodiment are achieved.

[0077] [Fifth Modification] Next, a fifth modified example will be described with reference to FIG. 11 is a plan view of the base plate portion 7 in the fifth modified example, viewed from the side of the end plate portion 8. FIG. 11 corresponds to FIG. In the above-described embodiment, the position of the inner surface 51a of the substrate protrusion 51 is described as being on an imaginary circle C passing through the radially outermost part of the column portion 9 centered on the first rotation axis A1, or is located radially outward of the imaginary circle C. However, the present invention is not limited to this, and as shown in FIG. 11, the board protrusion 51 may be formed with a protrusion 51d that protrudes inward in the radial direction.

[0078] The protrusion 51d is disposed between the pillar portions 9 adjacent in the circumferential direction. The protrusion 51d extends along the periphery of the crank insertion recess 7e. However, this is not limiting, and the protrusion 51d does not have to extend along the periphery of the crank insertion recess 7e.

[0079] Even with this configuration, the base plate protrusions 51 and the end plate protrusions 62 can restrict axial movement of each of the oscillating external gears 15, 16. A gap G1 can be secured between the end face 15e of the first oscillating external gear 15 and the end face 7f of the base plate portion 7, and a gap G2 can be secured between the end face 16e of the second oscillating external gear 16 and the end face 8f of the end plate portion 8. This allows the lubricant to be sufficiently distributed throughout the entire interior of the reduction gear 1, reliably improving the drive efficiency of the reduction gear 1. The protrusions 51, 62 can minimize runout of each of the oscillating external gears 15, 16, and minimize rattling of each of the oscillating external gears 15, 16.

[0080] [Other variations] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention.

[0081] For example, in the above embodiment, the main bearings 41, 42, which are so-called angular contact ball bearings, are provided to rotatably support the carrier 3 on the case 2. However, this is not limited to this, and various bearings can be used as the main bearings 41, 42. For example, in addition to rolling bearings in general, sliding bearings and the like can also be used.

[0082] In the above embodiment, the first main bearing 41 has been described as having an outer race 43 fitted to the first case bearing retaining surface 22a and an inner race 44 fitted to the base plate bearing retaining surface 7c. The second main bearing 42 has been described as having an outer race 43 fitted to the second case bearing retaining surface 22b and an inner race 44 fitted to the end plate bearing retaining surface 8c. However, this is not limited to this, and the outer races 43 of the main bearings 41, 42 may be integral with the case 2. In this case, this also includes a case where the outer races 43 are cast into the bearing retaining surfaces 22a, 22b. The inner races 44 of the main bearings 41, 42 may be integral with the corresponding base plate portion 7 or end plate portion 8. In this case, this also includes a case where the inner races 44 are cast into the bearing retaining surfaces 7c, 8c.

[0083] In the above embodiment, the case 2, the base plate 7, and the end plate 8 are each formed from spheroidal graphite cast iron. For example, the case where FCD450 is used as the spheroidal graphite cast iron has been described. However, this is not limited to this, and various materials can be used for the case 2, the base plate 7, and the end plate 8.

[0084] In the above embodiment, the reduction mechanism 4 is described as having two oscillating external gears 15, 16. However, this is not limited to this, and the reduction mechanism 4 may have at least one oscillating external gear. When there is one oscillating external gear, the base plate protrusion 51 and the end plate protrusion 62 may abut against both surfaces of the oscillating external gear, respectively. In the above embodiment, the crank insertion recess 7e for rotatably supporting the shaft main body 13c of the crankshaft 13 is formed in the base plate portion 7. However, this is not limitative, and the crank insertion recess 7e may be a hole.

[0085] In the above-described embodiment, the substrate protrusion 51 is formed along the outer periphery of the end face 7f of the substrate portion 7. The end plate protrusion 62 is formed along the outer periphery of the end face 8f of the end plate portion 8. However, this is not limited to this, and the substrate protrusion 51 does not have to be formed completely along the outer periphery of the end face 7f of the substrate portion 7. The end plate protrusion 62 does not have to be formed completely along the outer periphery of the end face 8f of the end plate portion 8. However, it is preferable that the substrate protrusion 51 is formed on the outer periphery of the end face 7f of the substrate portion 7. It is preferable that the end plate protrusion 62 is formed on the outer periphery of the end face 8f of the end plate portion 8. By configuring in this manner, the same effects as those of the above-described embodiment can be achieved.

[0086] In the above embodiment, the end plate protrusions 62 and the base plate protrusions 51 are described as being circumferentially offset from each other when viewed from the axial direction. In other words, the end plate protrusions 62 and the base plate protrusions 51 are described as being staggered when viewed from the axial direction. Here, "staggered" includes both cases where the end plate protrusions 62 and the base plate protrusions 51 are slightly offset from each other in the circumferential direction when viewed from the axial direction, and cases where they are completely offset from each other when viewed from the axial direction. In other words, it includes both cases where a portion of the end plate protrusions 62 and a portion of the base plate protrusions 51 overlap when viewed from the axial direction, and cases where there is no overlap between the end plate protrusions 62 and the base plate protrusions 51.

[0087] Among the embodiments disclosed in this specification, those that are comprised of multiple objects may be integrated, and conversely, those that are comprised of a single object may be separated into multiple objects. Regardless of whether they are integrated, it is sufficient that they are configured to achieve the object of the invention. [Explanation of symbols]

[0088] 1...Reduction device (gear device) 2. Case 5...Internal pin (internal gear) 7...Board part (first carrier) 8...End plate (second carrier) 9...Column part 13...Crankshaft 13a...First eccentric part (eccentric part) 13b...Second eccentric part (eccentric part) 13c...shaft body 15...First oscillating external gear (oscillating external gear) 15e,16e...end face 16... Second oscillating external gear (oscillating external gear) 41...First main bearing (bearing) 42...Second main bearing (bearing) 43...Outer Race 44...Inner race 45...Rolling element 51...Substrate convex portion (first convex portion) 51c,62b…Tip surface 61...Pedestal surface 62...End plate convex portion (second convex portion)

Claims

1. a cylindrical case having an internal gear; a first carrier disposed radially inside the case and rotatably supported by the case via a first bearing; a second carrier disposed radially inside the case and facing the first carrier in the axial direction of the case, and rotatably supported by the case via a second bearing; at least one crankshaft rotatably supported by the first carrier and the second carrier and receiving an external rotational force; at least one oscillating external gear disposed between the first carrier and the second carrier and meshed with the internal gear; Equipped with The crankshaft is A shaft body; an eccentric portion provided on the shaft body and eccentric with respect to a rotation axis of the shaft body; and the oscillating external gear is rotatably supported by the eccentric portion, the first carrier is provided with a first protrusion that abuts against an end face of the oscillating external gear on the first carrier side, and the second carrier is provided with a second protrusion that abuts against an end face of the oscillating external gear on the second carrier side. Gearing.

2. The first bearing and the second bearing are an outer race provided in the case; an inner race disposed radially inside the outer race and provided on the corresponding first carrier or second carrier; a plurality of rolling elements disposed between the outer race and the inner race; Equipped with the first protrusion protrudes toward the oscillating external gear beyond the inner race of the first bearing, the second protrusion protrudes toward the oscillating external gear beyond the inner race of the second bearing, 2. The gear device of claim 1.

3. a plurality of the first convex portions and a plurality of the second convex portions are provided, the plurality of first protrusions and the plurality of second protrusions are arranged to be shifted from each other in the circumferential direction when viewed from the axial direction, 3. A gear device according to claim 1 or claim 2.

4. the first convex portion is provided on an outer circumferential portion of a surface of the first carrier that faces the oscillating external gear in the axial direction, the second convex portion is provided on an outer circumferential portion of a surface of the second carrier that faces the oscillating external gear in the axial direction, 4. The gearing of claim 3.

5. the first carrier includes a plurality of pillar portions that protrude toward the second carrier and that maintain a constant distance between the first carrier and the second carrier; The first protrusion is provided at least radially outward of the column portion.

5. The gearing of claim 4.

6. the second carrier has a base surface against which the tip of the column portion abuts, a tip surface of the second protrusion is disposed on the same plane as the base surface; 6. The gearing of claim 5.

7. the internal gear includes a plurality of internal pins provided on an inner peripheral surface of the case and arranged at equal intervals in the circumferential direction, a part of an axial end surface of the internally toothed pin abuts against the first bearing and the second bearing; 2. The gear device of claim 1.

Images