JP6757149B2 - Gear device - Google Patents

Description

The present invention relates to a gear device having a crankshaft that imparts swing rotation to the 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 swing gear.

Patent Document 1 has an input gear arranged in an outer cylinder. The input gear is located between the two swing gears. The gear portion formed on the rotating shaft of the motor meshes with the input gear. When the motor rotates the gear portion, the input gear also rotates. As a result, the crankshaft to which the input gear is attached also rotates. The crankshaft gives the two rocking gears rocking rotation. 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 orbit around 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 technique disclosed in Patent Document 1, since the input gear is arranged in the outer cylinder, the crankshaft may be short. Therefore, the gear device of Patent Document 1 can have a small dimension in the extending direction of the output shaft.

Japanese Unexamined Patent Publication No. 2009-185986

The maximum value of 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 attempts to increase the product value under the structure disclosed in Patent Document 1 without increasing the total length of the crankshaft, the designer is installed with the input gear. It is necessary to give a large value to the diameter of the mounting part of the crankshaft. However, the increase in the diameter of the attachment site results in interference between the input gear and the internal teeth of 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 capable of transmitting a large torque from an input gear to a crankshaft.

The gear device according to one aspect of the present invention includes an outer cylinder having a plurality of internal teeth formed in an annular shape around a predetermined output shaft, a oscillating gear that meshes with the plurality of internal teeth, and a center of the oscillating gear. Is relative to the outer cylinder around the output shaft under the swing rotation of the swing gear and the crankshaft that gives the swing gear a swing rotation so as to orbit around the output shaft. A carrier for rotating the crankshaft and an input gear for rotating the crankshaft are provided. The crankshaft includes a journal that rotates around a predetermined transmission shaft, and an eccentric portion to which the swing gear is attached and eccentrically rotates with respect to the transmission shaft to give the swing rotation to the swing gear. Includes a fixed portion located between the journal and the eccentric portion to which the input gear is fixed. The fixed portion is larger in diameter than the eccentric portion, the fixed portion is a spline shaft complementary to a spline hole formed in the input gear, and the small diameter of the spline shaft is the diameter of the eccentric portion. A first bearing that is larger than the sum of the eccentricity of the eccentric portion from the transmission shaft and into which the journal is fitted, the journal penetrates, and is sandwiched between the first bearing and the spline shaft. A holding ring is further provided, and the outer diameter of the first holding ring is larger than the large diameter of the spline shaft .

According to the above configuration, 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, so that even if the fixed portion is larger in diameter than the eccentric portion, Interference between the input gear and the plurality of internal teeth is unlikely to occur. The designer who designs the gear device can give the fixed portion a large diameter, which allows a large torque transmission from the input gear to the crankshaft. Moreover, 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 to the journal.

With respect 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 shaft length than the eccentric portion, the crankshaft can have a shorter shaft length. This results in a short shaft length of the gear device.

With respect to the above configuration, the fixing portion may be a spline shaft complementary to the 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, the small diameter of the spline shaft is larger than the sum of the diameter of the eccentric portion and the eccentric amount of the eccentric portion from the transmission shaft. Since the input gear can mesh with the spline shaft over the entire shaft length of the spline shaft, the crankshaft does not become unnecessarily long.

With respect to the above configuration, the gear device further includes a second bearing into which the eccentric portion is fitted, and a second holding ring through which the eccentric portion is inserted and sandwiched between the second bearing and the spline shaft. May be 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, 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, so that the input gear is unlikely to fall off to the eccentric portion.

With respect to the above configuration, the gear device may further include a main bearing fitted in 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 internal 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 above configuration, since the second inner peripheral surface of the outer cylinder holds the main bearing, the internal teeth are not formed on the second inner peripheral surface unlike the first inner 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. The designer who designs the gear device can give the fixed portion a large diameter, which allows a large torque transmission from the input gear to the crankshaft.

With respect to the above configuration, the tooth tip circle of the input gear may protrude from the tooth tip circle defined by the plurality of internal teeth.

According to the above configuration, the tooth tip circle of the input gear may protrude from the tooth tip circle defined by the plurality of internal teeth, so that the designer can give a large diameter to the fixed portion. 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 the schematic sectional drawing of the reduction gear exemplified as a gear device. It is a schematic sectional view of the reduction gear along the line AA shown in FIG. It is a schematic partial sectional view of the crankshaft assembly of the reduction gear shown in FIG. It is a conceptual diagram which shows the relationship between the tooth tip circle of the internal tooth ring formed by a plurality of internal tooth pins, and the tooth tip circle of an input gear.

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

1 and 2 show a speed reducer 100 exemplified as the gear device of the first 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. The speed reducer 100 will be described with reference to FIGS. 1 and 2.

The speed reducer 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), and two main units. It includes bearings 610 and 620. The driving force generated by the motor (not shown) or another drive source (not shown) is input to each of the three crankshaft assemblies 500. The driving force input to each of the three crankshaft assemblies 500 is transmitted to the gear portion 400 arranged 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, 620 allows relative rotational movement between the outer cylinder 200 and the carrier 300. The 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 portion 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 columnar internal space in which the carrier 300, the gear portion 400, and the crankshaft assembly 500 are housed. 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 of the internal tooth pins 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 in the inner wall of the case 210. Therefore, each of the internal tooth pins 220 is properly held by the case 210.

As shown in FIG. 2, the plurality of internal tooth pins 220 are arranged in an annular shape around the output shaft OAX at substantially constant intervals. The half peripheral surfaces of each of the plurality of internal tooth pins 220 project from the inner wall of the case 210 toward the output shaft OAX. Therefore, the plurality of internal tooth pins 220 function as internal teeth that mesh with the gear portion 400. In this embodiment, the plurality of internal teeth are exemplified by a plurality of internal tooth pins 220.

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

The base 310 includes a substantially disk-shaped substrate portion 311 (see FIG. 1) and three shaft portions 312 (see FIG. 2). The substrate portion 311 is substantially coaxial with the end plate 320. That is, the output shaft OAX corresponds to the central shaft 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 portion 400. The inner surface 313 and the outer surface 314 are along a virtual plane (not shown) orthogonal to the output axis OAX.

The central through hole 315 (see FIG. 1) and the 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 shaft OAX. The output shaft OAX corresponds to the central shaft 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 shaft TAX is defined at a position away from the output shaft 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 shaft TAX. The transmission shaft TAX corresponds to the rotation center shaft of the crankshaft assembly 500 and the center shaft of the holding through hole 316. A portion of the crankshaft assembly 500 is arranged 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 portion 400. The inner surface 323 and the outer surface 324 are along a virtual plane (not shown) orthogonal to the output axis OAX.

The central through hole 325 (see FIG. 1) and the 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 shaft OAX. The output shaft OAX corresponds to the central shaft 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 shaft TAX. The transmission shaft TAX corresponds to the central shaft of the holding through hole 326. A portion of the crankshaft assembly 500 is arranged 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 tip surface of each of the three shaft portions 312. The end plate 320 may be connected to the tip surfaces of each of the three shaft portions 312 by means of 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 portion 400 is arranged between the inner surface 313 of the substrate portion 311 and the inner surface 323 of the end plate 320. The three shaft portions 312 penetrate the gear portion 400 and are connected to the end plate 320.

As shown in FIG. 1, the gear unit 400 includes two swing gears 410 and 420. The oscillating gear 410 is arranged between the end plate 320 and the oscillating gear 420. The oscillating gear 420 is arranged 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 oscillating gears 410 and 420 includes a plurality of external teeth 430 (see FIG. 2) that project toward the inner wall of the case 210. When the crankshaft assembly 500 rotates around the transmission shaft TAX, the oscillating gears 410 and 420 orbit (ie, oscillate) in the case 210 while engaging the plurality of external teeth 430 with the plurality of internal tooth pins 220. Dynamic rotation). During this time, the centers of the oscillating gears 410 and 420 orbit around the output shaft OAX. The relative rotation between the outer cylinder 200 and the carrier 300 is caused by the oscillating rotation of the oscillating 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-holes 422 of the oscillating gear 420 and the circular through-holes of the oscillating gear 410 cooperate with the holding through holes 316 and 326 of the substrate portion 311 and the end plate 320 to accommodate the crankshaft assembly 500. Form a space.

The three trapezoidal through holes 413 (FIG. 1 shows one of the three trapezoidal through holes 413) are formed in the swing gear 410. The three trapezoidal through holes 423 (see FIG. 2) are formed in the swing gear 420. The shaft portion 312 of the carrier 300 penetrates the trapezoidal through holes 413 and 423. The size of the trapezoidal through holes 413 and 423 is 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 will be 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 the shaft (not shown) of the motor (not shown) in the central space formed by the central through holes 315,325,411,421. .. When the motor rotates the shaft, the input gear 510 rotates about the transmission shaft TAX.

The crankshaft 520 includes a first journal 521, a second journal 522, a first eccentric portion 523, a second eccentric portion 524, and a holding disc 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 the annular space between the first journal 521 and the inner wall of the end plate 320 forming the holding through hole 326. The journal bearing 532 is fitted into the annular space between the second journal 522 and the inner wall of the substrate portion 311 forming the holding through hole 316.

The first eccentric portion 523 is located between the first journal 521 and the second eccentric portion 524. The second eccentric portion 524 is located between the second journal 522 and the first eccentric portion 523. The crank bearing 541 is fitted in an annular space between the first eccentric portion 523 and the inner wall of the oscillating gear 410 forming the circular through hole. The crank bearing 542 is fitted in an annular space between the second eccentric portion 524 and the inner wall of the oscillating gear 420 forming the circular through hole 422.

The first journal 521 is coaxial with the second journal 522 and rotates about the transmission axis TAX. Each of the first eccentric portion 523 and the second eccentric portion 524 is formed in a columnar shape and is eccentric from the transmission shaft TAX. Each of the first eccentric portion 523 and the second eccentric portion 524 eccentrically rotates with respect to the transmission shaft TAX, and gives swing rotation to the swing gears 410 and 420. The circumferential phase difference between the oscillating 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 this 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 faces of the holding disk 525 project radially from the peripheral surfaces of the first journal 521 and the first eccentric portion 523. The holding disc 525 is substantially coaxial with the first journal 521 and the second journal 522 and rotates about the transmission shaft TAX. The input gear 510 is attached to the holding disc 525. The inner surface 323 of the end plate 320 is recessed from the connection portion between the end plate 320 and the base 310. The holding disc 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 this embodiment, the fixing portion is exemplified by a holding disk 525.

The maximum value of the torque transmitted from the input gear 510 to the crankshaft 520 is determined by the product of the diameter of the holding disc 525 and the shaft length (dimension in the direction along the transmission shaft TAX). If the product of the diameter of the holding disc 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 disc 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, so that the designer designing the speed reducer 100 , A small value may be given to the shaft length of the holding disk 525. As shown in FIG. 3, the designer sets the axial length of the holding disk 525 to be 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 tooth pins 220 are fitted into the plurality of grooves formed in the first inner peripheral surface 211. On the other hand, the second inner peripheral surface 212 is used for holding the main bearing 610 and draws a smooth circular contour without a 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 tooth tip circle of the internal tooth ring formed by the plurality of internal tooth pins 220 and the tooth 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 a second inner peripheral surface 212. Therefore, the input gear 510 can rotate around the transmission shaft TAX without interfering with the internal tooth pin 220. This means that the input gear 510 may be arranged so that the tip circle of the input gear 510 protrudes from the 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 reduction gears can employ a variety of structures, such as spline coupling and key coupling, for the mechanical connection between the input gear and the holding disc. Spline couplings are known as coupling structures suitable for transmitting large torques. In the second embodiment, the spline coupling between the input gear and the holding disc is described.

As shown in FIG. 3, the input gear 510 is spline-coupled to the holding disc 525. Spline processing is applied to the outer peripheral surface of the holding disk 525. A spline hole is formed in the center of the input gear 510. The holding disc 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 disc 525) is larger than the sum of the diameter of the first eccentric portion 523 and the eccentric amount of the first eccentric portion 523 from the transmission shaft TAX. Therefore, the tool used to machine the spline shaft does not interfere with other parts of the crankshaft 520. As a result, the holding disc 525 can function as a spline shaft over the entire shaft length.

As shown in FIG. 3, the crankshaft assembly 500 further includes thin plate-shaped stopper rings 551 and 552 that secure the input gear 510 on the holding disc 525. The first journal 521 penetrates the stopper ring 551 and the journal bearing 531. The operator assembling 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. As a result, the stopper ring 551 is sandwiched between the journal bearing 531 and the holding disk 525. The stopper ring 551 has a larger outer diameter than the large diameter of the spline shaft (holding disc 525). Therefore, the stopper ring 551 can prevent the input gear 510 from being displaced toward the first journal 521. In this embodiment, the journal is exemplified by the first journal 521. The first bearing is exemplified by the journal bearing 531. The first holding ring is exemplified by the stopper ring 551.

The first eccentric portion 523 penetrates the stopper ring 552 and the crank bearing 541. The operator assembling 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 has a larger outer diameter than the large diameter of the spline shaft (holding disc 525). Therefore, the stopper ring 552 can prevent the input gear 510 from being displaced toward the first eccentric portion 523. In this embodiment, the eccentric portion is exemplified by the first eccentric portion 523. The second bearing is exemplified by the crank bearing 541. The second holding ring is exemplified by the stopper ring 552.

In the above embodiment, the holding disk 525 is integrally formed with the first journal 521 and the first eccentric portion 523. Alternatively, the holding disc 525 may be a disc member formed differently from the crankshaft 520. In this case, the holding disc 525 may be spline-coupled 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 device described in connection with the other other embodiment. The above design principle is also applicable to center crank type gear devices.

The principles of the above embodiments are suitably utilized in various gear devices.

100 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Reducer 200 ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ Outer cylinder 211 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First inner peripheral surface 212 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Second inner peripheral surface 220 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Internal tooth pin 300 ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Carrier 410 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Swing gear 510 ..................... Input gear 520 .....・ ・ ・ ・ ・ ・ ・ Crankshaft 521 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First Journal 523 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First eccentric part 525 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Holding disk 531 ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Journal bearing 541 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Crank bearings 551,552 ... Stopper ring 610 ...・ ・ ・ ・ Main bearing OAX ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Output shaft TAX ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Transmission axis

Claims (6)

An outer cylinder having a plurality of internal teeth formed in an annular shape around a predetermined output shaft,
A oscillating gear that meshes with the plurality of internal teeth,
A crankshaft that gives the oscillating gear oscillating rotation so that the center of the oscillating gear orbits 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.
With an input gear for rotating the crankshaft,
The crankshaft includes a journal that rotates around a predetermined transmission shaft, and an eccentric portion to which the swing gear is attached and eccentrically rotates with respect to the transmission shaft to give the swing rotation to the swing gear. Includes a fixed portion located between the journal and the eccentric portion to which the input gear is fixed.
The fixed portion is larger in diameter than the eccentric portion and
The fixing portion is a spline shaft complementary to the spline hole formed in the input gear.
The small diameter of the spline shaft is larger than the sum of the diameter of the eccentric portion and the eccentric amount of the eccentric portion from the transmission shaft.
The first bearing into which the journal is fitted and
Further comprising a first holding ring through which the journal penetrates and sandwiched between the first bearing and the spline shaft.
A gear device in which the outer diameter of the first holding ring is larger than the large diameter of the spline shaft. The gear device according to claim 1, wherein the fixed portion has a shorter axial length than the eccentric portion. Diameter before Symbol spline shaft, a gear device according to claim 1 or 2 larger than the sum of the eccentricity of the eccentric portion from a diameter between the transmission axis of the eccentric portion. The second bearing into which the eccentric portion is fitted and
A second holding ring through which the eccentric portion penetrates and is sandwiched between the second bearing and the spline shaft is further provided.
The outer diameter of the second holding ring, gear device according to claim 1 is greater than diameter of the spline shaft. Further provided with 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 internal 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 4 , wherein the input gear is surrounded by the second inner peripheral surface. The gear device according to claim 5 , wherein the tooth tip circle of the input gear protrudes from the tooth tip circle defined by the plurality of internal teeth.

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