Gear device

Abstract

To provide a gear device in which gears constituting a plurality of power transmission paths can be disposed while saving the space, furthermore, can firmly fix members for supporting gears provided with a transmission path to the other members.SOLUTION: A reduction mechanism 4 includes: a center gear 30 including external teeth 32 in an end; a crankshaft 13 provided parallel to the center gear 30; a transmission spur gear 14 provided integral with the crankshaft 13 in an end of the crankshaft 13 and engaging the external tooth 32; and an intermediate spur gear supported to the end of the crankshaft 13 so as to be freely relatively rotatable and engaging the external tooth 32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, a so-called eccentric oscillating reduction gear has been known as a gear device. This type of gear device includes an internal gear (external cylinder), a carrier rotatably supported by the internal gear via a bearing, multiple crankshafts (crank shafts) rotatably supported by the carrier and having eccentric portions, and an oscillating external gear (external gear) housed within the carrier. A driven member, such as a robot arm, is fastened and fixed to the carrier by multiple bolts. The multiple bolts are arranged along the outer periphery of the carrier.

[0003] The crankshafts are arranged in a circumferential direction, and a crankshaft gear is provided at the axial end of each crankshaft. The external gear is rotatably supported by the crankshaft and meshes with the internal gear. A hole penetrating the axial direction is formed on the inside of the carrier and the external gear in the radial direction. A cylindrical center shaft (cylinder) is inserted into this hole. A spur gear meshing with the crankshaft gear is provided at the axial end of the center shaft. The spur gear is meshed with an intermediate gear in addition to the crankshaft gear. The intermediate gear is arranged between the crankshaft gears arranged in the circumferential direction. The intermediate gear is meshed with an input gear that rotates when driven by the electric motor.

[0004] With this configuration, when the electric motor is driven, the center shaft is rotated via the input gear and intermediate gear. The rotation of the center shaft is transmitted to the crankshaft via the spur gear and crankshaft gear. As a result, when the crankshaft rotates, the external gear oscillates while meshing with the internal gear. The oscillating rotation of the external gear rotates the carrier via the crankshaft. In this way, the rotation of the input gear, which rotates in conjunction with the drive of the electric motor, is decelerated and output from the carrier, and if the internal gear is fixed, it drives a driven member fixed to the carrier. If the carrier is fixed, the internal gear can also be used as an output.

[0005] An eccentric oscillating reduction gear transmits the rotation of the input gear to the center shaft via an intermediate gear, thereby equalizing the load on each crankshaft. Furthermore, by providing an intermediate gear, the axis of the input gear can be offset from the axis of the center shaft (carrier). This makes it possible, for example, to route a cable around the center shaft. This allows for greater flexibility in the layout of the reduction gear and reduces the space required for arranging the reduction gear. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5231530 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-described conventional technology, the spur gear, crankshaft gear, intermediate gear, and input gear that constitute multiple power transmission paths are arranged at the axial end of the reduction gear transmission, which requires securing space for arranging these gears, resulting in a problem that the axial end of the reduction gear transmission cannot be effectively utilized. Furthermore, since it is necessary to secure a space for arranging multiple gears at the axial end of the reduction gear device, it is difficult to secure a sufficient space for fixing the driven member to the carrier, which results in a problem of limitations on how firmly the carrier and the driven member can be fixed together.

[0008] The present invention provides a gear device that can arrange gears that constitute multiple power transmission paths in a space-saving manner, and that can firmly fix a member that supports the gears to which the transmission paths are provided to other members. [Means for solving the problem]

[0009] A gear device according to one embodiment of the present invention comprises a first shaft having a toothed portion at an end thereof, a second shaft arranged parallel to the first shaft, a first gear arranged integrally with the second shaft at the end thereof and meshing with the toothed portion, and a second gear supported on the end of the second shaft so as to be rotatable relative to the second shaft and meshing with the toothed portion.

[0010] By configuring it in this manner, a gear device having multiple power transmission paths in which power is transmitted in the order of the second gear, external teeth and first shaft, and first gear and second shaft can be installed in a space-saving manner when viewed from the axial direction of the first shaft and the second shaft. As a result, the member that rotatably supports the first shaft and the second shaft can have sufficient space to be used for fastening to other members. Therefore, a fastening portion such as a female screw portion can be provided in this space. Therefore, the member that rotatably supports the first shaft and the second shaft can be firmly fastened to other members (driven members).

[0011] In the above configuration, the device comprises an internal gear having internal teeth on its inner peripheral surface, a carrier arranged radially inside the internal gear and supported rotatably relative to the internal gear, a fixing portion arranged along the outer periphery of the carrier for fixing the carrier to another member, the first shaft arranged coaxially with the carrier at the radial center of the carrier and supported rotatably relative to the carrier, a plurality of second shafts rotatably supported by the carrier and arranged around the first shaft, and an external gear housed in the carrier and meshed with the internal teeth, wherein the second shaft 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, the external gear is rotatably supported on the eccentric portion, and the second gear is provided on one of the plurality of second shafts.

[0012] In the above configuration, the first gear and the second gear are arranged side by side in the axial direction, and the second gear is supported by the second shaft via a bearing. [Effects of the Invention]

[0013] The above-described gear device allows gears that form a plurality of power transmission paths to be arranged in a space-saving manner, and in turn allows members that support the gears to which the transmission paths are provided to be firmly fixed. [Brief explanation of the drawings]

[0014] [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 view taken along the arrow II in FIG. [Figure 3] FIG. 2 is an enlarged view of part III in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of an intermediate spur gear and its surroundings according to a first modified example of the embodiment of the present invention. [Figure 5] FIG. 10 is an enlarged cross-sectional view of an intermediate spur gear and its surroundings according to a second modified example of the embodiment of the present invention. [Figure 6]FIG. 10 is an enlarged cross-sectional view of an intermediate spur gear and its surroundings according to a third modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, an embodiment of the present invention will be described with reference to the drawings.

[0016] <Drive unit> FIG. 1 is a cross-sectional view of a reduction gear transmission 1. As shown in FIG. As shown in FIG. 1, the reduction gear 1 is a so-called eccentric oscillating reduction gear. The reduction gear 1 is attached to a driven member (another member) such as a robot arm (not shown). The reduction gear 1 drives the driven member by reducing the rotation of an electric motor (not shown) and outputting it. The reduction gear 1 includes a cylindrical case 2, a carrier 3 rotatably provided radially inside the case 2, and a reduction mechanism (an example of a gear device in the claims) 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.

[0017] In the following description, the central axis and rotation axis will be 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 referred to simply as the radial direction. The central side of the case 2 in the axial direction will be referred to as the central side of the axial direction. The side opposite the central side in the axial direction will be referred to as the outer side in the axial direction.

[0018] <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. The outer flange portion 2a and the bolt holes 2b are used to fix the reduction gear transmission 1 (case 2) to a driven member (not shown).

[0019] A plurality of pin grooves 2e are formed in the inner peripheral surface 2d of the case 2 along the axial direction. The pin grooves 2e are arranged at equal intervals in the circumferential direction. An internally toothed pin 5 is fitted into each pin groove 2e. The internally toothed pin 5 functions as an internal tooth that meshes with externally toothed gears 15 and 16 (described later) of the reduction mechanism 4. The carrier 3 is rotatably supported by the case 2 via main bearings 41 and 42.

[0020] <Career> The carrier 3 includes a disk-shaped base plate 7 and an end plate 8 arranged opposite each other in the axial direction. The base plate 7 and the end plate 8 are made of, for example, spheroidal graphite cast iron (ductile cast iron). For example, FCD450 is used as the spheroidal graphite cast iron.

[0021] <Board> FIG. 2 is a view taken along the arrow II in FIG. 1 and 2, the base plate portion 7 is formed in a disk shape. 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.

[0022] A substrate shaft insertion hole 7d is formed in the radial center of the substrate portion 7. A shaft bearing holding surface 7f is formed in the substrate shaft insertion hole 7d at the axial center. A plurality of (for example, three in this embodiment) crank insertion holes 7g are formed around the base plate shaft insertion hole 7d in the base plate portion 7. The crank insertion holes 7g are arranged at equal intervals in the circumferential direction.

[0023] A center recess 9 is formed coaxially with the base plate shaft insertion hole 7d on a first end face 7h of the base plate portion 7 opposite the end plate portion 8. The center recess 9 is formed in a circular shape when viewed in the axial direction. The radius of the center recess 9 is slightly larger than the distance between the axis of the base plate shaft insertion hole 7d and the axis of the crank insertion hole 7g. The center recess 9 communicates with the base plate shaft insertion hole 7d.

[0024] A gear accommodating recess 10 is formed in the first end face 7h of the base plate portion 7, coaxially with each crank insertion hole 7g. The gear accommodating recess 10 communicates with the center recess 9. The gear accommodating recess 10 is formed in an arc shape centered on the axis of the crank insertion hole 7g, projecting radially outward from the outer periphery of the center recess 9. The gear accommodating recess 10 communicates with the crank insertion hole 7g. The center recess 9 and gear accommodating recess 10 accommodate external teeth (an example of a teeth portion in the claims) 32 and a transmission spur gear (an example of a first gear in the claims) 14, which will be described later.

[0025] A plurality of female mounting threads 12 are formed on the first end surface 7h of the base plate portion 7 so as to surround the periphery of the center recess 9. In other words, the plurality of female mounting threads 12 are formed on the first end surface 7h of the base plate portion 7 near the outer periphery and over the entire surface between adjacent gear housing recesses 10 in the circumferential direction. The female mounting threads 12 are used to secure the reduction gear transmission 1 (carrier 3) to a driven member (not shown). In other words, the driven member (not shown) is secured to the carrier 3 by fastening bolts (not shown) to the respective female mounting threads 12.

[0026] Three pillar portions 11 are formed on the second end surface 7i of the base plate portion 7 on the end plate portion 8 side so as to protrude toward the end plate portion 8. Each pillar portion 11 is disposed between adjacent crank insertion holes 7g in the circumferential direction. The three pillar portions 11 are disposed at equal intervals in the circumferential direction. A plurality of (for example, two) female screw portions 26 and post pin holes 27 are formed on the tip surface 11a of each post portion 11. 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).

[0027] A shaft bearing 20 is provided on the shaft bearing holding surface 7f of the base plate portion 7. The shaft bearing 20 is, for example, a ball bearing. That is, an outer race 20a of the shaft bearing 20 is fitted onto the shaft bearing holding surface 7f. A cylindrical center gear (an example of the first shaft in the claims) 30 is fitted into the inner race 20b of the shaft bearing 20. The center gear 30 has a cylindrical portion 31 and external teeth 32 integrally formed on the outer circumferential surface of the cylindrical portion 31.

[0028] The inner race 20b of the shaft bearing 20 is fitted onto the outer peripheral surface of the cylindrical portion 31. The external teeth 32 are arranged on the outer peripheral surface of the cylindrical portion 31 on the axially opposite side to the end plate portion 8. The external teeth 32 are formed uniformly in the axial direction. The pitch circle diameter of the external teeth 32 is larger than the outer diameter of the cylindrical portion 31. The axial end of the inner race 20b abuts against the stepped surface 32a of the external teeth 32. This determines the axial positioning of the center gear 30 relative to the base plate portion 7.

[0029] The center gear 30, which is positioned relative to the base plate 7, has its external teeth 32 housed in the center recess 9. In this state, the end face 30a of the center gear 30 opposite the end plate 8 and the first end face 7h of the base plate 7 are positioned on approximately the same plane. In other words, the axial length of the external teeth 32 is approximately the same as the depth of the center recess 9.

[0030] <End plate> The end plate portion 8 is formed in a disk shape. An end plate shaft insertion hole 8d is formed through 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 8j (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 8j are arranged at equal intervals in the circumferential direction. Each crank insertion hole 8j is arranged coaxially with the crank insertion hole 7g in the base plate portion 7. In other words, the central axis A2 of the crank insertion holes 8j and 7g, which are axially opposed to each other, is parallel to the first rotation axis A1.

[0031] The end plate portion 8 is formed with a plurality of (for example, two) bolt insertion holes 34 and an end plate pin hole 35 at locations axially opposing the column portion 11 of the base plate portion 7. Each bolt insertion hole 34 is arranged coaxially with the female thread portion 26 of the column portion 11. The end plate pin hole 35 is arranged coaxially with the column pin hole 27. A bolt 91 is inserted into each of the bolt insertion holes 34 from the side opposite the base plate 7, and each bolt 91 is tightened into the female thread 26. A pin 92 is inserted or press-fitted into the end plate pin hole 35 and the column pin hole 27. This allows the base plate 7 and end plate 8 to be positioned with high precision, and then the end plate 8 is fixed to the base plate 7.

[0032] <Deceleration mechanism> The reduction mechanism 4 reduces the rotation of the electric motor (not shown) at a fixed ratio to rotate the carrier 3. The reduction mechanism 4 mainly comprises a center gear 30 rotatably supported on the base plate 7, three crankshafts (an example of the second shafts in the claims) 13 inserted into crank insertion holes 7g of the base plate 7 and crank insertion holes 8j of the end plate 8, a transmission spur gear 14 provided on each crankshaft 13, an intermediate spur gear (an example of the second gear in the claims) 50 provided on one of the three crankshafts 13, and two external gears 15, 16 (a first external gear 15 and a second external gear 16) provided between the base plate 7 and the end plate 8.

[0033] FIG. 3 is an enlarged view of part III in FIG. 1 to 3, the crankshaft 13 is rotatably supported by the base plate 7 and the end plate 8 via crank bearings 18 provided in the crank insertion holes 7g of the base plate 7 and the crank insertion holes 8j of the end plate 8. The crank bearings 18 are, for example, cylindrical roller bearings. However, the present invention is not limited to this, and various bearings can be used.

[0034] The crankshaft 13 has a shaft body 13a that rotates about a central axis A2, a support shaft 13d provided at the end of the shaft body 13a on the base plate portion 7 side, and a first eccentric portion 13b and a second eccentric portion 13c formed in the axial center of the shaft body 13a. Hereinafter, the central axis A2 will be referred to as the second rotation axis A2 of the crankshaft 13. Both axial ends of the shaft body 13a are rotatably supported by the carrier 3 (the base plate portion 7 and the end plate portion 8) via crank bearings 18.

[0035] The first eccentric portion 13b and the second eccentric portion 13c are eccentric from the second rotation axis A2. The first eccentric portion 13b and the second eccentric portion 13c are disposed adjacent to each other in the axial direction between the two crank bearings 18. In other words, the first eccentric portion 13b and the second eccentric portion 13c 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 13b and the second eccentric portion 13c are disposed with a phase angle shift of 180°.

[0036] The first external gear 15 and the second external gear 16 are rotatably supported on each crankshaft 13 via rocking bearings 19 at each of the eccentric portions 13b, 13c. The rocking bearings 19 are, for example, cylindrical roller bearings. However, the present invention is not limited to this, and various bearings can be used.

[0037] The first external gear 15 and the second external gear 16 are disposed between the base plate 7 and the end plate 8. The first external gear 15 and the second external gear 16 overlap in the axial direction. Through holes 15a, 16a are formed in the first external gear 15 and the second external gear 16. The outer peripheral surfaces of oscillating bearings 19 are fitted into the through holes 15a, 16a, respectively. As a result, when the first eccentric portion 13b and the second eccentric portion 13c are oscillatingly rotated by the rotation of the crankshaft 13, the first external gear 15 and the second external gear 16 are oscillatingly rotated via the oscillating bearing 19.

[0038] The first external gear 15 and the second external gear 16 are formed with openings 15b, 16b, respectively, to avoid interference with the column portion 11. Shaft insertion holes 15c, 16c are formed in the radial centers of the first external gear 15 and the second external gear 16. External teeth 15d, 16d are formed on the outer periphery of the first external gear 15 and the outer periphery of the second 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.

[0039] The transmission spur gear 14 is fitted and fixed to the support shaft 13d of each crankshaft 13. More specifically, a shaft-side spline 61 is formed on the outer circumferential surface of the support shaft 13d over most of the surface, from a position close to the shaft main body 13a to a tip 13e on the opposite side of the shaft main body 13a. A first retaining ring 70a is attached to the outer circumferential surface of the support shaft 13d on the shaft-side spline 61 closer to the shaft main body 13a, and a second retaining ring 70b is attached to the tip 13e side.

[0040] The transmission spur gear 14 is formed in a disk shape. A shaft insertion hole 14a is formed in the radial center of the transmission spur gear 14. A gear-side spline 62 is formed in the shaft insertion hole 14a. The shaft-side spline 61 and the gear-side spline 62 are fitted together, so that the transmission spur gear 14 is fitted to the support shaft 13d so as not to rotate relative to it. Teeth 14b are formed on the outer circumferential surface of the transmission spur gear 14.

[0041] The transmission spur gear 14 is positioned relative to the support shaft 13d when one surface of the transmission spur gear 14 abuts against a first retaining ring 70a attached to the support shaft 13d. The transmission spur gear 14 positioned on the support shaft 13d is then housed in the gear housing recess 10 of the base plate 7. In this state, the teeth 14b of the transmission spur gear 14 and the external teeth 32 of the center gear 30 are engaged with each other.

[0042] The intermediate spur gear 50 is provided axially alongside the transmission spur gear 14 on a support shaft 13d of one of the three crankshafts 13. More specifically, a bushing 63 is fitted onto the support shaft 13d, closer to the tip 13e than the transmission spur gear 14. A bushing-side spline 64 is formed on the inner peripheral surface of the bushing 63. The shaft-side spline 61 and the bushing-side spline 64 are fitted together, so that the bushing 63 is fitted onto the support shaft 13d so as not to rotate relative to it. The intermediate spur gear 50 is rotatably supported on the outer peripheral surface of the bushing 63 via a plurality of cylindrical rollers 65. Teeth 50a are formed on the outer peripheral surface of the intermediate spur gear 50.

[0043] A recess 51 is formed over most of the radial center of a surface 50b of the intermediate spur gear 50 opposite the transmission spur gear 14. The recess 51 is formed in a circular shape when viewed in the axial direction. A flat washer 52 fitted to the support shaft 13d is placed on a bottom surface 51a of the recess 51. A surface 52a of the flat washer 52 opposite the bottom surface 51a abuts against a second retaining ring 70b attached to the support shaft 13d.

[0044] This prevents the intermediate spur gear 50 from coming off the support shaft 13d and positions the intermediate spur gear 50 relative to the support shaft 13d. In this state, one surface 50b of the intermediate spur gear 50 and the first end surface 7h of the base plate portion 7 are positioned on approximately the same plane. The pitch circle diameter of the teeth 50a of the intermediate spur gear 50 is the same as the pitch circle diameter of the teeth 14b of the transmission spur gear 14. Therefore, the teeth 50a of the intermediate spur gear 50 mesh with the external teeth 32 of the center gear 30, just like the transmission spur gear 14.

[0045] In addition, an input gear 80 attached to the motor shaft of an electric motor (not shown) is meshed with the intermediate spur gear 50. The input gear 80 and the transmission spur gear 14 are not meshed with each other.

[0046] <Operation of the reduction gear> Next, the operation of the reduction gear 1 will be described. When the input gear 80 is rotated by the drive of an electric motor (not shown), the intermediate spur gear 50 meshing with the input gear 80 is rotated. The intermediate spur gear 50 is rotatably supported by the support shaft 13d. Therefore, only the intermediate spur gear 50 rotates without rotating the crankshaft 13. When the intermediate spur gear 50 rotates, the center gear 30 meshing with the intermediate spur gear 50 is rotated.

[0047] When the center gear 30 is rotated, the three transmission spur gears 14 meshed with the center gear 30 are simultaneously rotated. The corresponding crankshafts 13 are rotated integrally with these transmission spur gears 14. As a result, the external gears 15, 16 are 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 external gears 15, 16 is rotated on its axis such that the meshing points of the external teeth 15d, 16d with respect to the internal pins 5 (case 2) are sequentially shifted in the circumferential direction. This rotation is decelerated relative to the rotation of the crankshaft 13.

[0048] As each external gear 15, 16 rotates, each crankshaft 13 also rotates about the second rotation axis A2 while revolving around the first rotation axis A1. Each crankshaft 13 is rotatably supported by the carrier 3 (base plate portion 7, end plate portion 8). Therefore, as each crankshaft 13 revolves, the carrier 3 rotates.

[0049] As the carrier 3 rotates, the reduction gear 1 reduces the rotation of the electric motor and outputs it to a driven member (not shown). This drives the driven member. If the driven member were fixed, the reduction gear 1 would be able to reduce the rotation of the electric motor and output it from the case 2.

[0050] Incidentally, the driven member (not shown) fixed to the carrier 3 is fixed by fastening bolts (not shown) to a plurality of female mounting threads 12 formed on the first end face 7h of the base plate portion 7. The plurality of female mounting threads 12 are formed on the first end face 7h of the base plate portion 7 near the outer periphery and over the entire area between adjacent gear housing recesses 10 in the circumferential direction.

[0051] For example, suppose that the intermediate spur gear 50 for transmitting the rotation of the input gear 80 to the center gear 30 is not arranged next to the transmission spur gear 14 in the axial direction, but is arranged at a location different from the location where the transmission spur gear 14 is arranged as viewed from the axial direction. In such a case, the intermediate spur gear 50 is arranged between two transmission spur gears 14 that are adjacent in the circumferential direction. This reduces the space on the first end surface 7h of the base plate portion 7 for forming the female mounting thread portion 12. This reduces the fixing force between the carrier 3 and the driven member (not shown).

[0052] Therefore, according to the above-described embodiment, the transmission spur gear 14 and the intermediate spur gear 50 are provided on one crankshaft 13, thereby saving the space occupied by the transmission spur gear 14 and the intermediate spur gear 50 when viewed in the axial direction. As a result, a plurality of female mounting thread portions 12 can be formed on the first end face 7h of the base plate portion 7, near the outer periphery, and over the entire surface between adjacent gear housing recesses 10 in the circumferential direction. This allows the carrier 3 to be firmly fixed to a driven member (not shown).

[0053] Although the transmission spur gear 14 and the intermediate spur gear 50 are provided on a single crankshaft 13, the crankshaft 13 and the intermediate spur gear 50 are arranged to rotate freely relative to each other. This makes it possible to transmit power in the following order: input gear 80, intermediate spur gear 50, center gear 30, and transmission spur gear 14. In this way, the reduction mechanism 4 having multiple transmission paths (intermediate spur gear 50, center gear 30, transmission spur gear 14) can be installed in a space-saving manner as viewed in the axial direction. In an eccentric oscillating type reduction gear device such as the reduction gear device 1, a sufficient space can be secured on the first end face 7h of the base plate portion 7 for fixing a driven member (not shown).

[0054] The intermediate spur gear 50 is arranged alongside the transmission spur gear 14 in the axial direction. This allows the transmission spur gear 14 and the intermediate spur gear 50 to be arranged together. This allows the space occupied by the transmission spur gear 14 and the intermediate spur gear 50 to be saved accordingly. This allows the reduction mechanism 4 to be arranged in an even more space-saving manner.

[0055] [Variations] In the above embodiment, the intermediate spur gear 50 is supported on the support shaft 13d via the bushing 63 and the plurality of cylindrical rollers 65 so as to be rotatable relative to the support shaft 13d. The shaft-side splines 61 are formed on the outer peripheral surface of the support shaft 13d, and the bushing-side splines 64 are formed on the inner peripheral surface of the bushing 63. The shaft-side splines 61 and the bushing-side splines 64 are engaged with each other so as to be non-rotatable relative to the support shaft 13d. In other words, the support shaft 13d and the bushing 63 are spline-engaged. However, the present invention is not limited to this, and it is sufficient that the intermediate spur gear 50 is supported on the support shaft 13d so as to be rotatable relative to the support shaft 13d. More specific details will be described below.

[0056] 4 is an enlarged cross-sectional view of the intermediate spur gear 50 and its surroundings in the first modified example. FIG. 4 corresponds to FIG. 3 described above. 4, in the first modified example, the shaft-side spline 61 is not formed on the outer circumferential surface of the support shaft 13d at the location where the intermediate spur gear 50 is fitted. On the other hand, the bushing-side spline 64 is not formed on the inner circumferential surface of the bushing 63. The bushing 63 is simply fitted onto the outer circumferential surface of the support shaft 13d by, for example, press fitting.

[0057] 5 is an enlarged cross-sectional view of an intermediate spur gear 50 and its surroundings in the second modified example. FIG. 5 corresponds to FIG. 5, in the second modified example, a bushing 63 is not fitted to the outer peripheral surface of the support shaft 13d. A plurality of cylindrical rollers 65 are provided on the outer peripheral surface of the support shaft 13d. The intermediate spur gear 50 is rotatably supported on the support shaft 13d directly via the cylindrical rollers 65.

[0058] 6 is an enlarged cross-sectional view of an intermediate spur gear 50 and its surroundings in a third modified example. FIG. 6 corresponds to the above-mentioned FIG. As shown in FIG. 6, in the third modified example, an intermediate spur gear 50 is rotatably supported on a support shaft 13d via a deep groove ball bearing 75. In the third modification, various bearings can be used in place of the deep groove ball bearing 75.

[0059] Furthermore, the present invention is not limited to the above-described embodiments, and includes various modifications to the above-described embodiments without departing from the spirit of the present invention.

[0060] For example, in the above embodiment, the reduction mechanism 4 constituting the eccentric oscillating reduction gear 1 has been described as an example of a gear device. However, the present invention is not limited to this, and the gear device may include at least two shafts arranged in parallel (e.g., the center gear 30 and the crankshaft 13), a gear (e.g., the transmission spur gear 14) that is integrally provided on one of the two shafts and meshes with a gear (e.g., the external teeth 32) of the other shaft, and a gear (e.g., the intermediate spur gear 50) that is relatively rotatably provided on one of the two shafts and meshes with the other gear.

[0061] In the above embodiment, the reduction gear mechanism 4 has been described as having two external gears 15, 16. The reduction gear mechanism 4 has been described as having three crankshafts 13. However, this is not limited to this, and the reduction gear mechanism 4 may have at least one external gear. The number of crankshafts 13 may also be plural.

[0062] In the above embodiment, the main bearings 41, 42 are, for example, tapered roller bearings. However, this is not limiting, and various bearings can be used as the main bearings 41, 42 instead of tapered roller bearings.

[0063] In the above embodiment, the intermediate spur gear 50 is arranged side by side with the transmission spur gear 14 in the axial direction. However, this is not limiting, and the intermediate spur gear 50 does not have to be arranged side by side with the transmission spur gear 14 in the axial direction. The intermediate spur gear 50 may be arranged on the end of the crankshaft 13 opposite the end on which the transmission spur gear 14 is arranged, i.e., on the end plate 8 side. In this case, it is preferable that the end of the crankshaft 13 on the end plate 8 side protrudes outward in the axial direction via the end plate 8.

[0064] 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]

[0065] 1...Reduction device (gear device) 2...Case (internal gear) 3. Career 4...Reduction mechanism (gear device) 5...Inner tooth pin (inner tooth) 12...Female mounting thread (fixing part) 13...Crankshaft (second shaft) 13a...Shaft body 13b...First eccentric part (eccentric part) 13c…Second eccentric part (eccentric part) 14...Transmission spur gear (first gear) 15...First external gear (external gear) 16...Second external gear (external gear) 30...Center gear (first shaft) 32...External teeth (tooth part) 50...Intermediate spur gear (2nd gear)

Claims

1. a first shaft having teeth at an end thereof; a second shaft provided parallel to the first shaft; a first gear provided integrally with the second shaft at an end of the second shaft and meshing with the tooth portion; a second gear supported on an end of the second shaft so as to be relatively rotatable and meshed with the tooth portion; Equipped with Gearing.

2. an internal gear having internal teeth on an inner peripheral surface; a carrier that is disposed radially inside the internal gear and supported by the internal gear so as to be rotatable relative to the internal gear; a fixing portion disposed along an outer periphery of the carrier for fixing the carrier to another member; the first shaft disposed coaxially with the carrier at the radial center of the carrier and supported by the carrier so as to be rotatable relative to the carrier; a plurality of second shafts rotatably supported by the carrier and arranged around the first shaft; an external gear housed in the carrier and meshing with the internal teeth; Equipped with The second shaft 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 external gear is rotatably supported by the eccentric portion, The second gear is provided on one of the second shafts.

2. The gear device of claim 1.

3. The first gear and the second gear are arranged side by side in the axial direction, The second gear is supported on the second shaft via a bearing.

3. A gear device according to claim 1 or claim 2.

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