JP2017166562A - Gear device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology enabling a large torque to be transmitted from an input gear to a crank shaft to be transmitted.SOLUTION: This patent application discloses a gear device comprising: an outer cylinder having several inner teeth formed in an annular form around a predetermined output shaft; an oscillation gear engaged with several inner teeth; a crank shaft giving oscillating rotation to the oscillation gear so as to cause a center of the oscillation gear to rotate around the output shaft; a carrier rotated relatively around the output shaft in respect to the outer cylinder under an oscillation rotation of the oscillation gear; and an input gear for rotating the crank shaft. The crank shaft comprises: a journal rotated around a specified transmittance shaft; an eccentric part to which the oscillation gear is attached, eccentrically rotated with respect to the transmittance shaft and giving an oscillating rotation to the oscillation gear; and a fixed part positioned between the journal and the eccentric part and to which the input gear is fixed. The fixed part has a larger diameter than that of the eccentric part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gear device having a crankshaft that swings and rotates a gear.

  Various gear devices have been developed in various technical fields such as industrial robots and machine tools (see Patent Document 1). Patent Document 1 discloses a gear device having a rocking gear.

  Patent document 1 has the input gear arrange | positioned in the outer cylinder. The input gear is located between the two oscillating gears. A gear portion formed on the rotating shaft of the motor meshes with the input gear. When the motor rotates the gear unit, the input gear also rotates. As a result, the crankshaft to which the input gear is attached also rotates. The crankshaft provides oscillating rotation to the two oscillating gears. During the oscillating rotation, the two oscillating gears mesh with a plurality of internal teeth formed on the inner wall of the outer cylinder, and move around in the outer cylinder. As a result, the carrier connected to the outer cylinder or the crankshaft can rotate around the output shaft.

  According to the technology disclosed in Patent Document 1, the input gear is disposed in the outer cylinder, and therefore the crankshaft may be short. Therefore, the gear apparatus of patent document 1 can have a small dimension in the extending direction of an output shaft.

JP 2009-185986 A

  The maximum value of the torque transmitted from the input gear to the crankshaft depends on the product of the diameter of the mounting portion of the crankshaft to which the input gear is mounted and the shaft length dimension. If the product value is large, a large torque can be transmitted from the input gear to the crankshaft. If the product value is small, a small torque can be transmitted from the input gear to the crankshaft.

  If the designer who designs the gear device tries to increase the product value without increasing the overall length of the crankshaft under the structure disclosed in Patent Document 1, the designer can install the input gear. It is necessary to give a large value to the diameter of the mounting part of the crankshaft. However, an increase in the diameter of the attachment site results in interference between the input gear and the external teeth. Therefore, the technique disclosed in Patent Document 1 is not suitable for transmitting a large torque from the input gear to the crankshaft.

  An object of the present invention is to provide a technique that enables a large torque to be transmitted from an input gear to a crankshaft.

  A gear device according to an aspect of the present invention includes an outer cylinder having a plurality of inner teeth formed around an output shaft, a swing gear that meshes with the plurality of inner teeth, and a center of the swing gear. Is rotated around the output shaft so as to rotate around the output shaft, and relative to the outer cylinder around the output shaft under the swing rotation of the swing gear. A rotating carrier and an input gear for rotating the crankshaft. The crankshaft includes a journal that rotates around a predetermined transmission shaft, an eccentric portion to which the oscillating gear is attached, and an eccentric portion that rotates eccentrically with respect to the transmission shaft and applies the oscillating rotation to the oscillating gear. And a fixed portion that is positioned between the journal and the eccentric portion and to which the input gear is fixed. The fixed portion is larger in diameter than the eccentric portion.

  According to the above configuration, since the fixed portion to which the input gear is fixed is located between the journal and the eccentric portion to which the swing gear is attached, even if the fixed portion is larger in diameter than the eccentric portion, Interference between the input gear and the plurality of internal teeth of the external teeth is unlikely to occur. Since the designer who designs the gear device can give a large diameter to the fixed portion, a large torque can be transmitted from the input gear to the crankshaft.

  With regard to the above configuration, the fixed portion may be shorter in axial length than the eccentric portion.

  According to the above configuration, since the fixed portion is shorter in axial length than the eccentric portion, the crankshaft can have a short axial length. This results in a short shaft length of the gear device.

  With regard to the above configuration, the fixed portion may be a spline shaft that is complementary to a spline hole formed in the input gear. The small diameter of the spline shaft may be larger than the sum of the diameter of the eccentric portion and the eccentric amount of the eccentric portion from the transmission shaft.

  According to the above configuration, since the small diameter of the spline shaft is larger than the sum of the diameter of the eccentric portion and the amount of eccentricity of the eccentric portion from the transmission shaft, no rounded-up portion is generated in the processing of the spline shaft. Since the input gear can mesh with the spline shaft over the entire length of the spline shaft, the crankshaft does not become unnecessarily long.

  With regard to the above configuration, the gear device may further include a first bearing into which the journal is fitted, and a first holding ring through which the journal penetrates and is sandwiched between the first bearing and the spline shaft. . An outer diameter of the first holding ring may be larger than a large diameter of the spline shaft.

  According to the above configuration, since the outer diameter of the first holding ring sandwiched between the first bearing and the spline shaft is larger than the large diameter of the spline shaft, the input gear is unlikely to fall off the journal.

  With regard to the above configuration, the gear device further includes a second bearing into which the eccentric portion is fitted, and a second holding ring that passes through the eccentric portion and is sandwiched between the second bearing and the spline shaft. Also good. The outer diameter of the second holding ring may be larger than the large diameter of the spline shaft.

  According to the above configuration, since the outer diameter of the second holding ring sandwiched between the second bearing and the spline shaft is larger than the large diameter of the spline shaft, the input gear is unlikely to drop off to the eccentric portion.

  With respect to the above configuration, the gear device may further include a main bearing that is fitted into an annular space formed between the outer cylinder and the carrier. The outer cylinder may include a first inner peripheral surface on which the plurality of inner teeth are formed, and a second inner peripheral surface that holds the main bearing. The input gear may be surrounded by the second inner peripheral surface.

  According to the said structure, since the 2nd internal peripheral surface of an outer cylinder hold | maintains a main bearing, an internal tooth is not formed in a 2nd internal peripheral surface unlike a 1st internal peripheral surface. Since the input gear is surrounded by the second inner peripheral surface, interference between the input gear and the plurality of internal teeth of the external teeth is unlikely to occur. Since the designer who designs the gear device can give a large diameter to the fixed portion, a large torque can be transmitted from the input gear to the crankshaft.

  In the above configuration, the tip circle of the input gear may protrude from the tip circle defined by the plurality of internal teeth.

  According to the above configuration, the tip circle of the input gear may protrude from the tip circle defined by the plurality of internal teeth, so that the designer can give the fixed portion a large diameter. Therefore, the gear device can transmit a large torque from the input gear to the crankshaft.

  The gear device described above makes it possible to transmit a large torque from the input gear to the crankshaft.

It is a schematic sectional drawing of the reduction gear illustrated as a gear apparatus. It is a schematic sectional drawing of the reduction gear along an AA line shown by FIG. It is a schematic fragmentary sectional view of the crankshaft assembly of the reduction gear shown by FIG. It is a conceptual diagram showing the relationship between the tip circle of the internal tooth ring formed of a plurality of internal tooth pins and the tip circle of the input gear.

<First Embodiment>
In the first embodiment, an exemplary gear device capable of transmitting a large torque from an input gear to a crankshaft is described.

  FIG.1 and FIG.2 shows the reduction gear 100 illustrated as a gear apparatus of 1st Embodiment. FIG. 1 is a schematic cross-sectional view of the speed reducer 100. FIG. 2 is a schematic cross-sectional view of the speed reducer 100 along the line AA shown in FIG. With reference to FIG.1 and FIG.2, the reduction gear 100 is demonstrated.

  The reduction gear 100 includes an outer cylinder 200, a carrier 300, a gear portion 400, three crankshaft assemblies 500 (FIG. 1 shows one of the three crankshaft assemblies 500), two main shafts, Bearings 610 and 620. Driving forces generated by a motor (not shown) and other driving sources (not shown) are input to the three crankshaft assemblies 500, respectively. The driving force input to each of the three crankshaft assemblies 500 is transmitted to the gear portion 400 disposed in the internal space surrounded by the outer cylinder 200 and the carrier 300.

  As shown in FIG. 1, the two main bearings 610 and 620 are fitted into an annular space formed between the outer cylinder 200 and the carrier 300 surrounded by the outer cylinder 200. Each of the two main bearings 610 and 620 enables a relative rotational movement between the outer cylinder 200 and the carrier 300. A common central axis of the two main bearings 610 and 620 corresponds to the output shaft OAX. The outer cylinder 200 and the carrier 300 are relatively rotated around the output shaft OAX by the driving force transmitted to the gear unit 400.

  As shown in FIG. 2, the outer cylinder 200 includes a substantially cylindrical case 210 and a plurality of internal tooth pins 220. The case 210 defines a cylindrical internal space in which the carrier 300, the gear portion 400, and the crankshaft assembly 500 are accommodated. The plurality of internal tooth pins 220 are arranged in an annular shape along the inner peripheral surface of the case 210 to form an internal tooth ring.

  Each internal tooth pin 220 is a columnar member extending in the extending direction of the output shaft OAX. Each of the internal tooth pins 220 is fitted into a groove formed on the inner wall of the case 210. Therefore, each internal tooth pin 220 is appropriately held by the case 210.

  As shown in FIG. 2, the plurality of internal tooth pins 220 are annularly arranged around the output shaft OAX at a substantially constant interval. A half circumferential surface of each of the plurality of internal teeth pins 220 protrudes from the inner wall of the case 210 toward the output shaft OAX. Accordingly, the plurality of internal teeth pins 220 function as internal teeth that mesh with the gear portion 400. In the present embodiment, the plurality of internal teeth are exemplified by the plurality of internal teeth pins 220.

  As shown in FIG. 1, the carrier 300 includes a base portion 310 and an end plate 320. The carrier 300 is generally cylindrical. The end plate 320 has a substantially disk shape. The carrier 300 can rotate around the output axis OAX in the outer cylinder 200. Alternatively, the outer cylinder 200 can rotate around the output axis OAX around the carrier 300.

  The base portion 310 includes a substantially disc-shaped substrate portion 311 (see FIG. 1) and three shaft portions 312 (see FIG. 2). The substrate unit 311 is substantially coaxial with the end plate 320. That is, the output shaft OAX corresponds to the central axis of the substrate portion 311 and the end plate 320.

  The substrate portion 311 includes an inner surface 313 and an outer surface 314 opposite to the inner surface 313. The inner surface 313 faces the gear unit 400. The inner surface 313 and the outer surface 314 are along a virtual plane (not shown) orthogonal to the output axis OAX.

  A central through hole 315 (see FIG. 1) and three holding through holes 316 (FIG. 1 shows one of the three holding through holes 316) are formed in the substrate portion 311. The central through hole 315 extends between the inner surface 313 and the outer surface 314 along the output axis OAX. The output shaft OAX corresponds to the central axis of the central through hole 315. The centers of the three holding through holes 316 are arranged at substantially equal intervals on a virtual circle (not shown) centered on the output shaft OAX.

  FIG. 1 shows a transmission shaft TAX in addition to the output shaft OAX. The transmission axis TAX is defined at a position away from the output axis OAX. The transmission shaft TAX is substantially parallel to the output shaft OAX. The holding through hole 316 extends between the inner surface 313 and the outer surface 314 along the transmission axis TAX. The transmission shaft TAX corresponds to the rotation center axis of the crankshaft assembly 500 and the center axis of the holding through hole 316. A part of the crankshaft assembly 500 is disposed in the holding through hole 316.

  The end plate 320 includes an inner surface 323 and an outer surface 324 opposite to the inner surface 323. The inner surface 323 faces the gear unit 400. The inner surface 323 and the outer surface 324 are along a virtual plane (not shown) orthogonal to the output axis OAX.

  A central through hole 325 (see FIG. 1) and three holding through holes 326 (FIG. 1 shows one of the three holding through holes 326) are formed in the end plate 320. The central through hole 325 extends between the inner surface 323 and the outer surface 324 along the output axis OAX. The output shaft OAX corresponds to the central axis of the central through hole 325. The centers of the three holding through holes 326 are arranged at substantially equal intervals on a virtual circle (not shown) centered on the output shaft OAX. Each of the three holding through holes 326 extends between the inner surface 323 and the outer surface 324 along the transmission axis TAX. The transmission shaft TAX corresponds to the central axis of the holding through hole 326. A part of the crankshaft assembly 500 is disposed in the holding through hole 326. The three holding through holes 326 formed in the end plate 320 are substantially coaxial with the three holding through holes 316 formed in the substrate portion 311.

  Each of the three shaft portions 312 extends from the inner surface 313 of the substrate portion 311 toward the inner surface 323 of the end plate 320. The end plate 320 is connected to the front end surface of each of the three shaft portions 312. The end plate 320 may be connected to the front end surfaces of the three shaft portions 312 by reamer bolts, positioning pins, or other suitable fixing techniques. The principle of the present embodiment is not limited to a specific connection technique between the end plate 320 and each of the three shaft portions 312.

  As shown in FIG. 1, the gear unit 400 is disposed between the inner surface 313 of the substrate unit 311 and the inner surface 323 of the end plate 320. The three shaft portions 312 pass through the gear portion 400 and are connected to the end plate 320.

  As shown in FIG. 1, the gear unit 400 includes two oscillating gears 410 and 420. The swing gear 410 is disposed between the end plate 320 and the swing gear 420. The oscillating gear 420 is disposed between the substrate portion 311 and the oscillating gear 410. The oscillating gears 410 and 420 may be formed based on a common design drawing.

  Each of the rocking gears 410 and 420 includes a plurality of external teeth 430 (see FIG. 2) that protrude toward the inner wall of the case 210. When the crankshaft assembly 500 rotates around the transmission shaft TAX, the swing gears 410 and 420 rotate around the case 210 (that is, the swing gears 410) while meshing the plurality of external teeth 430 with the plurality of internal teeth pins 220. Dynamic rotation). During this time, the centers of the rocking gears 410 and 420 circulate around the output shaft OAX. The relative rotation between the outer cylinder 200 and the carrier 300 is caused by the swinging rotation of the swinging gears 410 and 420.

  The central through hole 411 is formed at the center of the swing gear 410. The central through hole 421 is formed at the center of the swing gear 420. The central through hole 411 communicates with the central through hole 325 of the end plate 320 and the central through hole 421 of the swing gear 420. The central through hole 421 communicates with the central through hole 315 of the substrate portion 311 and the central through hole 411 of the swing gear 410. The central through holes 411 and 421 of the oscillating gears 410 and 420 are larger in diameter than the central through holes 315 and 425 of the substrate portion 311 and the end plate 320.

  As shown in FIG. 2, three circular through holes 422 are formed in the swing gear 420. Similarly, three circular through holes are formed in the swing gear 410. The circular through hole 422 of the oscillating gear 420 and the circular through hole of the oscillating gear 410 cooperate with the holding through holes 316 and 326 of the base plate portion 311 and the end plate 320 to accommodate the crankshaft assembly 500. Create a space.

  Three trapezoidal through holes 413 (FIG. 1 shows one of the three trapezoidal through holes 413) are formed in the swing gear 410. Three trapezoidal through holes 423 (see FIG. 2) are formed in the rocking gear 420. The shaft portion 312 of the carrier 300 passes through the trapezoidal through holes 413 and 423. The sizes of the trapezoidal through holes 413 and 423 are determined so as not to interfere with the shaft portion 312.

  FIG. 3 is a schematic partial cross-sectional view of the crankshaft assembly 500. The crankshaft assembly 500 is described with reference to FIGS. 1 to 3.

  Each of the three crankshaft assemblies 500 includes an input gear 510, a crankshaft 520, two journal bearings 531 and 532, and two crank bearings 541 and 542. The input gear 510 meshes with a gear portion (not shown) formed on a shaft (not shown) of a motor (not shown) in a central space formed by the central through holes 315, 325, 411, and 421. . When the motor rotates the shaft, the input gear 510 rotates around the transmission axis TAX.

  The crankshaft 520 includes a first journal 521, a second journal 522, a first eccentric part 523, a second eccentric part 524, and a holding disk 525. The first journal 521 is inserted into the holding through hole 326 of the end plate 320. The second journal 522 is inserted into the holding through hole 316 of the substrate portion 311. The journal bearing 531 is fitted into an annular space between the first journal 521 and the inner wall of the end plate 320 that forms the holding through hole 326. The journal bearing 532 is fitted into an annular space between the second journal 522 and the inner wall of the substrate portion 311 that forms the holding through hole 316.

  The first eccentric part 523 is located between the first journal 521 and the second eccentric part 524. The second eccentric part 524 is located between the second journal 522 and the first eccentric part 523. The crank bearing 541 is fitted into an annular space between the first eccentric portion 523 and the inner wall of the swing gear 410 that forms a circular through hole. The crank bearing 542 is fitted into an annular space between the second eccentric portion 524 and the inner wall of the swing gear 420 that forms the circular through hole 422.

  The first journal 521 is coaxial with the second journal 522 and rotates around the transmission axis TAX. Each of the first eccentric portion 523 and the second eccentric portion 524 is formed in a cylindrical shape and is eccentric from the transmission shaft TAX. Each of the first eccentric portion 523 and the second eccentric portion 524 rotates eccentrically with respect to the transmission shaft TAX, and swings and rotates the swing gears 410 and 420. The rotational phase difference between the rocking gears 410 and 420 is determined by the difference in the eccentric direction between the first eccentric portion 523 and the second eccentric portion 524. In the present embodiment, the eccentric portion is exemplified by the first eccentric portion 523.

  The holding disk 525 is located between the first journal 521 and the first eccentric portion 523. Both end surfaces of the holding disk 525 protrude in the radial direction from the peripheral surfaces of the first journal 521 and the first eccentric portion 523. The holding disk 525 is substantially coaxial with the first journal 521 and the second journal 522 and rotates around the transmission axis TAX. The input gear 510 is attached to the holding disk 525. An inner surface 323 of the end plate 320 is recessed from a connection portion between the end plate 320 and the base portion 310. The holding disk 525 and the input gear 510 can rotate in the space between the recessed portion of the inner surface 323 and the swing gear 410. In the present embodiment, the fixing portion is exemplified by the holding disk 525.

  The maximum value of torque transmitted from the input gear 510 to the crankshaft 520 is determined by the product of the diameter of the holding disk 525 and the shaft length (dimension in the direction along the transmission shaft TAX). If the product value of the diameter of the holding disk 525 and the shaft length is large, a large torque can be transmitted from the input gear 510 to the crankshaft 520. As shown in FIG. 3, the holding disk 525 is larger in diameter than each of the first eccentric portion 523, the second eccentric portion 524, the first journal 521, and the second journal 522. A small value may be given to the axial length of the holding disk 525. As shown in FIG. 3, the designer makes the axial length of the holding disk 525 much shorter than the axial length of each of the first journal 521, the second journal 522, the first eccentric portion 523, and the second eccentric portion 524. can do. This results in a short shaft length of the entire crankshaft 520. Therefore, the dimension between the outer surfaces 314 and 324 of the carrier 300 can also be set to a small value.

  As shown in FIG. 1, the case 210 includes a first inner peripheral surface 211 and a second inner peripheral surface 212. The plurality of internal teeth pins 220 are fitted into a plurality of grooves formed on the first inner peripheral surface 211. On the other hand, the second inner peripheral surface 212 is used to hold the main bearing 610 and draws a smooth circular contour having no groove. The main bearing 610 is fitted into an annular space formed between the outer peripheral surface of the end plate 320 and the second inner peripheral surface 212.

  FIG. 4 is a conceptual diagram showing the relationship between the tip circle of the internal tooth ring formed by the plurality of internal teeth pins 220 and the tip circle of the input gear 510. The speed reducer 100 will be further described with reference to FIGS. 1 and 4.

  As shown in FIG. 1, the input gear 510 is surrounded by the second inner peripheral surface 212. Therefore, the input gear 510 can rotate around the transmission axis TAX without interfering with the internal tooth pin 220. This means that the input gear 510 may be arranged so that the tooth tip circle of the input gear 510 protrudes from the tooth tip circle of the internal tooth ring, as shown in FIG. Therefore, the designer can give a large value to the diameter of the holding disk 525. As a result, a large torque is transmitted from the input gear 510 to the crankshaft 520.

Second Embodiment
Designers designing the reduction gear can employ various structures such as spline coupling and key coupling for the mechanical connection between the input gear and the holding disk. Spline coupling is known as a suitable coupling structure for transmitting large torques. In the second embodiment, a spline connection between the input gear and the holding disk is described.

  As shown in FIG. 3, the input gear 510 is splined to the holding disk 525. Spline processing is applied to the outer peripheral surface of the holding disk 525. A spline hole is formed at the center of the input gear 510. The holding disk 525 is inserted into the spline hole of the input gear 510 and functions as a spline shaft complementary to the spline hole.

  As shown in FIG. 3, the small diameter of the spline shaft (holding disk 525) is larger than the sum of the diameter of the first eccentric portion 523 and the amount of eccentricity of the first eccentric portion 523 from the transmission shaft TAX. Therefore, the tool used for machining the spline shaft does not interfere with other parts of the crankshaft 520. As a result, the holding disk 525 can function as a spline shaft over the entire axial length.

  As shown in FIG. 3, the crankshaft assembly 500 further includes thin plate-like stopper rings 551 and 552 for fixing the input gear 510 on the holding disk 525. The first journal 521 passes through the stopper ring 551 and the journal bearing 531. An operator who assembles the crankshaft assembly 500 inserts the first journal 521 into the stopper ring 551 and then fits the journal bearing 531 and the first journal 521 together. As a result, the stopper ring 551 is sandwiched between the journal bearing 531 and the holding disk 525. The stopper ring 551 is larger in outer diameter than the large diameter of the spline shaft (holding disk 525). Therefore, the stopper ring 551 can prevent the displacement of the input gear 510 toward the first journal 521. In the present embodiment, the journal is exemplified by the first journal 521. The first bearing is exemplified by a journal bearing 531. The first retaining ring is exemplified by a stopper ring 551.

  The first eccentric portion 523 passes through the stopper ring 552 and the crank bearing 541. An operator who assembles the crankshaft assembly inserts the first eccentric portion 523 into the stopper ring 552 and then fits the first eccentric portion 523 and the crank bearing 541. As a result, the stopper ring 552 is sandwiched between the crank bearing 541 and the holding disk 525. The stopper ring 552 is larger in outer diameter than the large diameter of the spline shaft (holding disk 525). Therefore, the stopper ring 552 can prevent the displacement of the input gear 510 toward the first eccentric portion 523. In the present embodiment, the eccentric portion is exemplified by the first eccentric portion 523. The second bearing is exemplified by a crank bearing 541. The second retaining ring is exemplified by a stopper ring 552.

  In the above-described embodiment, the holding disk 525 is formed integrally with the first journal 521 and the first eccentric portion 523. Alternatively, the holding disk 525 may be a disk member formed differently from the crankshaft 520. In this case, the holding disk 525 may be splined or key-coupled to the crankshaft 520.

  The design principles described in connection with the various embodiments described above are applicable to various gear devices. Some of the various features described in connection with one of the various embodiments described above may be applied to the gear apparatus described in connection with another other embodiment. The design principle described above can also be applied to a center crank type gear device.

  The principle of the above-described embodiment is suitably used for various gear devices.

100 ... reducer 200 ...・ ・ ・ ・ Outer cylinder 211 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First inner peripheral surface 212 ... 2nd inner peripheral surface 220 ... Internal tooth pin 300 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Carrier 410 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Oscillating gear 510 ... Input gear 520 ...・ ・ ・ ・ ・ ・ ・ Crankshaft 521 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First Journal 523 ························ First eccentric portion 525 ··········· ............... Journal bearing 541 ... ... Crank bearings 551, 552 ......... Stopper ring 610 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Main bearing OAX ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Output shaft TAX ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... Transmission shaft

Claims (7)

An outer cylinder having a plurality of internal teeth formed in a ring around a predetermined output shaft;
A rocking gear meshing with the plurality of internal teeth;
A crankshaft that imparts oscillating rotation to the oscillating gear such that the center of the oscillating gear circulates around the output shaft;
A carrier that rotates relative to the outer cylinder around the output shaft under the swing rotation of the swing gear;
An input gear for rotating the crankshaft,
The crankshaft includes a journal that rotates around a predetermined transmission shaft, an eccentric portion to which the oscillating gear is attached, and an eccentric portion that rotates eccentrically with respect to the transmission shaft and applies the oscillating rotation to the oscillating gear. A fixed portion that is positioned between the journal and the eccentric portion and to which the input gear is fixed;
The fixed portion is a gear device that is larger in diameter than the eccentric portion. The gear device according to claim 1, wherein the fixed portion is shorter in axial length than the eccentric portion. The fixed portion is a spline shaft complementary to a spline hole formed in the input gear,
The gear device according to claim 1, wherein a small diameter of the spline shaft is larger than a sum of a diameter of the eccentric portion and an eccentric amount of the eccentric portion from the transmission shaft. A first bearing into which the journal is inserted;
A first retaining ring that penetrates the journal and is sandwiched between the first bearing and the spline shaft;
The gear device according to claim 3, wherein an outer diameter of the first holding ring is larger than a large diameter of the spline shaft. A second bearing into which the eccentric portion is fitted;
A second retaining ring that penetrates the eccentric part and is sandwiched between the second bearing and the spline shaft;
The gear device according to claim 4, wherein an outer diameter of the second holding ring is larger than a large diameter of the spline shaft. A main bearing fitted in an annular space formed between the outer cylinder and the carrier;
The outer cylinder includes a first inner peripheral surface on which the plurality of inner teeth are formed, and a second inner peripheral surface that holds the main bearing,
The gear device according to any one of claims 1 to 5, wherein the input gear is surrounded by the second inner peripheral surface. The gear apparatus according to claim 6, wherein a tip circle of the input gear protrudes from a tip circle defined by the plurality of internal teeth.

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