JP7364420B2 - power transmission device - Google Patents

Description

The present invention relates to a power transmission device such as a speed reducer.

In rotating equipment such as industrial robots and machine tools, power transmission devices such as reduction gears are used to transmit the rotation of a rotational drive source (for example, see Patent Document 1).

The power transmission device described in Patent Document 1 is an eccentric oscillating gear type speed reducer, and includes a cylindrical case, a carrier (support block) rotatably held within the case, and a rotatable speed reducer that is rotatably held in the carrier. A crankshaft supported by the crankshaft, a rocking gear that pivots and rotates within the case in response to rotation of an eccentric region of the crankshaft, and a plurality of internally toothed pins rotatably held on the inner peripheral surface of the case. There is. In the case of this power transmission device, the rotation of the rotational drive source is input to the crankshaft. Further, a plurality of pin grooves are formed along the axial direction on the inner circumferential surface of the case, and an internally toothed pin is rotatably held in each pin groove. External teeth that mesh with a plurality of internal pins are formed on the outer peripheral surface of the rocking gear. The number of external teeth is set to one less than the number of internal pins. Therefore, when the rocking gear rotates in response to the rotation of the crankshaft, it is reduced to a predetermined reduction ratio while meshing with the internal pin, and rotates in a direction opposite to the rotating direction. The rotational component of the rocking gear is transmitted to the carrier through the crankshaft. The carrier is connected to a rotating device to be used, and transmits the reduced power of the rotational drive source to the rotating device.

The crankshaft of the power transmission device described above has an eccentric region that transmits turning force to the rocking gear, and a pair of shaft support regions arranged on both sides of the eccentric region in the axial direction. The pair of shaft support regions are configured by tapered surfaces that taper toward the ends in the axial direction. Each shaft support region is rotatably supported in a shaft support hole formed in the carrier via a tapered roller bearing. In a tapered roller bearing, a plurality of tapered rollers are arranged between an inner race (inner ring) and an outer race (outer ring) so as to be able to roll freely. Tapered roller bearings allow a carrier to support the radial load and axial load that are applied to the crankshaft when power is transmitted by the crankshaft.

Japanese Patent Application Publication No. 2018-132181

However, the power transmission device described in Patent Document 1 uses a tapered roller bearing with many components to support the crankshaft on a carrier (support block). For this reason, the cost of parts around the crankshaft bearing increases, which tends to cause an increase in the product cost of the power transmission device.

The present invention provides a power transmission device that can simplify the configuration around a crankshaft bearing and reduce product costs.

A power transmission device according to one aspect of the present invention includes a support block disposed within a case , a shaft support region forming an inner race surface on an outer peripheral surface, and an eccentric region disposed adjacent to the shaft support region. and cylindrical rollers that are rolling elements that rotatably support the shaft support region of the crankshaft on the support block, and the outer circumferential surface of the shaft support region of the crankshaft is connected to the shaft support region of the crankshaft. It is constituted by a tapered surface that tapers toward the axial end of the shaft .

In the case of the power transmission device of this embodiment, since the outer circumferential surface of the shaft support region of the crankshaft constitutes the inner race surface, there is no need for an inner race exclusively for the bearing. Therefore, in the power transmission device of this embodiment, the number of parts can be reduced and product cost can be reduced.

The crankshaft has a first support region and a second support region arranged on both sides of the eccentric region in the axial direction, and at least one of the first support region and the second support region is located in the shaft support region. It is also possible to configure .

The support block may have a shaft support hole that supports the shaft support region, and at least a portion of an inner circumferential surface of the shaft support hole may constitute an outer race surface that comes into contact with the rolling element.

In this case, since the shaft support hole of the support block constitutes the outer race surface, there is no need for an outer race exclusively for the bearing. Therefore, when this configuration is adopted, the number of parts can be further reduced, and product costs can be further reduced.

It is desirable that the inner peripheral surface of the shaft support hole has a contact angle greater than 0° and less than 10°.

It is desirable that the inner circumferential surface of the shaft support hole and the contact surface of the rolling element have the same hardness.

An outer displacement regulating surface for regulating axially outer displacement of the rolling element may be integrally formed on the inner periphery of the shaft support hole.

It is desirable that the inner race surface has a contact angle greater than 0° and less than 10°.

It is desirable that the outer circumferential surface of the shaft support region and the contact surface of the rolling element have the same hardness.

The shaft support region may have an inner displacement regulating surface that regulates axially inward displacement of the cylindrical roller.

The above-described power transmission device has a simple configuration with a small number of parts, and the crankshaft can be rotatably supported by the support block, so that the product cost can be reduced.

FIG. 1 is a side view of an industrial robot according to an embodiment of the present invention. FIG. 1 is a partially sectional front view of a speed reducer (power transmission device) according to an embodiment of the present invention. 3 is a sectional view taken along line III-III in FIG. 2. FIG. FIG. 3 is a cross-sectional view taken along line IV-IV in FIG. 2;

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a side view of an industrial robot 1. FIG.
The industrial robot 1 of this embodiment is an articulated robot having a plurality of rotatable joints. In the industrial robot 1, arm parts 3, 4, 5, and 6 are rotatably connected in this order to a base 2 installed on an installation surface. A knuckle portion 7 is rotatably connected to the arm portion 6 on the distal end side. A reduction gear 10, which is one form of a power transmission device, is attached to the knuckle portion 7. The knuckle portion 7 has a built-in drive motor (not shown), and rotational torque is input from the drive motor to the input portion of the reducer 10 . For example, a gripping head (not shown) for gripping an article is attached to the output side of the speed reducer 10.

FIG. 2 is a partially sectional front view of the reducer 10 viewed from the input side. 3 is a sectional view taken along the line III--III in FIG. 2, and FIG. 4 is a sectional view taken along the line IV--IV in FIG. 2. Note that the cross-sectional portion in FIG. 2 corresponds to the cross-section taken along line II-II in FIG. 3.
The reducer 10 includes a case 11 having a generally cylindrical shape, a first carrier block 13A rotatably held on the inner peripheral surface of the case 11, a second carrier block 13B, and a first carrier block 13A. , and a plurality of (for example, three) crankshafts 14 rotatably supported by the second carrier block 13B, a first rocking gear 15A that pivots together with the two eccentric regions 14b of each crankshaft 14, and , and a second rocking gear 15B.
In this embodiment, the first carrier block 13A and the second carrier block 13B constitute a support block that rotatably supports the crankshaft 14. Further, the first carrier block 13A and the second carrier block 13B constitute a first block and a second block that are fastened and fixed to each other.

The first carrier block 13A includes a perforated disk-shaped substrate portion 13Aa, and a plurality of support portions 13Ab extending from the end surface of the substrate portion 13Aa toward the second carrier block 13B. The second carrier block 13B is formed in the shape of a disc with holes. In the first carrier block 13A, the end surfaces of the support columns 13Ab are butted against the end surfaces of the second carrier block 13B, and each support section 13Ab is fastened and fixed to the second carrier block 13B with bolts 16. Note that reference numeral 17 in the figure is a positioning pin for positioning the second carrier block 13B on each support column 13Ab before fastening with the bolts 16.

An axial gap is ensured between the substrate portion 13Aa of the first carrier block 13A and the second carrier block 13B. A first swing gear 15A and a second swing gear 15B are arranged in this gap.
Note that escape holes 19 are formed in the first rocking gear 15A and the second rocking gear 15B, through which each support column 13Ab of the first carrier block 13A passes. The escape hole 19 is formed to be sufficiently larger than the outer surface shape of the support column 13Ab so that each support column 13Ab does not interfere with the rotational movement of the first rocking gear 15A and the second rocking gear 15B.

The case 11 includes a cylindrical case body 11a and a flange 11b that protrudes radially outward from the outer peripheral surface of the case body 11a. The case body 11a and the flange 11b are integrally formed by casting or the like.

The case body 11a is disposed across the outer peripheral surface of the substrate portion 13Aa of the first carrier block 13A and the outer peripheral surface of the second carrier block 13B. A base plate portion 13Aa of a first carrier block 13A and a second carrier block 13B are rotatably supported via bearings 12 on both axial edges of the case body 11a. Further, on the inner peripheral surface of the axially central region of the case body 11a (the region facing the outer peripheral surfaces of the first rocking gear 15A and the second rocking gear 15B), first and second carrier blocks 13A, 13B are provided. A plurality of pin grooves 18 are formed extending parallel to the rotation center axis c1. A substantially cylindrical internal pin 20 is rotatably housed in each pin groove 18 . A plurality of internally toothed pins 20 attached to the inner circumferential surface of the case body 11a are opposed to the respective outer circumferential surfaces of the first swing gear 15A and the second swing gear 15B.

The first swing gear 15A and the second swing gear 15B are formed to have an outer diameter slightly smaller than the inner diameter of the case body 11a. External teeth 15Aa and 15Ba are formed on the outer peripheral surfaces of each of the first oscillating gear 15A and the second oscillating gear 15B, which mesh with and contact a plurality of internally toothed pins 20 arranged on the inner periphery of the case body 11a. has been done. The number of external teeth 15Aa and 15Ba formed on the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B is slightly smaller than the number of internally toothed pins 20 (pin grooves 18) (for example, one less) is set.

The plurality of crankshafts 14 are arranged on the same circumference around the rotation center axis c1 of the first carrier block 13A and the second carrier block 13B. Each crankshaft 14 is rotatably supported by a first carrier block 13A and a second carrier block 13B via bearings 21. Each crankshaft 14 has a pair of shaft support regions 14a arranged apart from each other in the axial direction, and two eccentric regions 14b arranged between the pair of shaft support regions 14a.
In this embodiment, one shaft support region 14a constitutes a first support region, and the other shaft support region 14a constitutes a second support region.

A gear mounting portion 14c is formed at one axial end of the crankshaft 14 adjacent to the shaft support region 14a. The outer circumferential surface S1 of each shaft support region 14a is constituted by a tapered surface that tapers toward the end of the crankshaft 14 in the axial direction. Further, each shaft support region 14a is inserted into a first support hole 13Aa-1 formed in the first carrier block 13A (substrate part 13Aa) and a second support hole 13Ba-1 formed in the second carrier block 13B. and is rotatably supported by these via bearings 21.
In this embodiment, the first support hole 13Aa-1 and the second support hole 13Ba-1 constitute a shaft support hole.

The bearing 21 is constituted by an angular bearing having cylindrical rollers 21a as rolling elements. The inner peripheral surface S2 of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B is constituted by a tapered surface that tapers toward the outside in the axial direction. There is. The inner circumferential surface S2 of the first and second support holes 13Aa-1 and 13Ba-1 is formed to be parallel to the outer circumferential surface S1 of the corresponding shaft support region 14a of the crankshaft 14. In the case of this embodiment, the outer circumferential surface S1 of the shaft support region 14a of the crankshaft 14 constitutes the inner race surface of the bearing 21, and the inner circumferential surface S2 of the first and second support holes 13Aa-1 and 13Ba-1 constitutes the inner race surface of the bearing 21. , constitutes the outer race surface of the bearing 21.

The entire crankshaft 14 is carburized and hardened, including the outer circumferential surface S1 of the shaft support region 14a. Further, the inner peripheral surfaces S2 of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B are subjected to induction hardening. Further, the plurality of cylindrical rollers 21a of the bearing 21 are rotatably held in a cage 27 so that the entire cylindrical rollers 21a are arranged in a truncated conical shape. The outer circumferential surface S1 of the shaft support region 14a and the inner circumferential surface S2 of the first and second support holes 13Aa-1 and 13Ba-1 have the same hardness as the outer circumferential surface (contact surface) of the cylindrical roller 21a.

The contact angle of the inner race surface (outer peripheral surface S1 of the shaft support region 14a) on the crankshaft 14 side with the cylindrical roller 21a is greater than 0° and less than 10°. Similarly, the contact angle of the outer race surface (inner peripheral surface S2 of the first support hole 13Aa-1 and second support hole 13Ba-1) with respect to the cylindrical roller 21a on the first and second carrier blocks 13A, 13B side is 0°. The angle is larger than 10° and less than 10°.

The axially inner portion of the shaft support region 14a of the crankshaft 14 has an inner displacement that expands in diameter in a stepped manner from the axially inner end of the shaft support region 14a and comes into contact with the axially inner end surface of the cylindrical roller 21a. A regulating surface 36 is formed. When the cylindrical roller 21a is assembled to each shaft support region 14a of the crankshaft 14, the inner displacement regulating surface 36 comes into contact with the axially inner end surface of the cylindrical roller 21a and prevents the cylindrical roller 21a from moving axially inward. Regulate displacement.

Further, in the inner regions of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B, from the axially outer end of the inner circumferential surface S2 (outer race surface) An outer displacement regulating surface 35 is formed which has a reduced diameter in a step-like manner and comes into contact with the axially outer end surface of the cylindrical roller 21a. The outer displacement regulating surface 35 is pressed against the axially outer end surface of the corresponding cylindrical roller 21a by bolting the second carrier block 13B to the first carrier block 13A with the crankshaft 14 assembled therein. , thereby applying a preload to the cylindrical roller 21a.

The two eccentric regions 14b of the crankshaft 14 have respective central axes c3 and c4 eccentric with respect to the central axis c2 of the shaft support region 14a. Furthermore, the two eccentric regions 14b are eccentric so that their phases are shifted by 180° around the central axis c2 of the shaft support region 14a (the central axis of the crankshaft 14).

Further, each eccentric region 14b of the crankshaft 14 passes through the first swing gear 15A and the second swing gear 15B, respectively. Each eccentric region 14b is rotatably engaged with a support hole 22 formed in the first rocking gear 15A and the second rocking gear 15B via an eccentric bearing 23 (cylindrical roller bearing).

In the reducer 10 of this embodiment, when the plurality of crankshafts 14 rotate in one direction in response to an external force, each eccentric region 14b of the crankshafts 14 turns in the same direction with a predetermined radius, and accordingly, the first oscillation occurs. The movable gear 15A and the second oscillating gear 15B rotate (swing) in the same direction with the same radius. At this time, each of the external teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B mesh with a plurality of internally toothed pins 20 held on the inner periphery of the case body 11a.
Note that the gear mounting portion 14c of each crankshaft 14 passes through the second shaft support hole 13Ba-1 of the second carrier block 13B and projects outward in the axial direction of the second carrier block 13B. A crankshaft gear 28 is attached to the gear attachment portion 14c protruding from the second carrier block 13B. Each crankshaft gear 28 meshes with an input gear (not shown). The input gear rotates in response to the driving force of a drive motor (not shown).

In the reducer 10 of this embodiment, the number of external teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B is slightly smaller than the number of internally toothed pins 20 on the case body 11a side. Therefore, while the first swing gear 15A and the second swing gear 15B make one revolution, the first swing gear 15A and the second swing gear 15B move from the internal pin 20 on the case body 11a side. It receives a reaction force in the direction of rotation and rotates by a predetermined pitch in the direction opposite to the direction of rotation. As a result, the first and second carrier blocks 13A and 13B, which are engaged with the first and second swing gears 15A and 15B via the crankshaft 14, It also rotates in the same direction and at the same pitch. As a result, the rotation of the crankshaft 14 is decelerated and output as rotation of the first and second carrier blocks 13A, 13B.
In addition, in this embodiment, since the two eccentric regions 14b of the crankshaft 14 are eccentric so as to be shifted by 180 degrees around the axis, the rotational phases of the first swing gear 15A and the second swing gear 15B are shifted by 180 degrees. It turns out.

Here, the flange 11b on the outer periphery of the case 11 is provided with mutually parallel flat surfaces at the top, bottom, left and right portions in FIG. As a result, the flange 11b is provided with four arc-shaped parts and four direct-shaped parts that connect the ends of the circumferentially adjacent arc-shaped parts. In the case of the present embodiment, the arc-shaped portion constitutes a high region 11b-H with a constant protrusion height from the outer peripheral surface of the case body 11a, and the linear portion constitutes a high region 11b-H with a constant protrusion height from the outer peripheral surface of the case body 11a. constitutes a low region 11b-L lower than the high region 11b-H.

A plurality of bolt insertion holes 29 passing through the flange 11b along the axial direction of the case 11 are formed in each high region 11b-H of the flange 11b. The bolt insertion holes 29 are formed at equal intervals along the circumferential direction of the case body 11a. A bolt (not shown) for fastening and fixing the reducer 10 to the knuckle portion 7 (see FIG. 1) of the industrial robot 1 is inserted into each bolt insertion hole 29. In the reducer 10, a part of the case body 11a (the region on the right side of the flange 11b in FIGS. 3 and 4) is fitted into the fitting hole of the knuckle portion 7, and in this state, the high region 11b-H of the flange 11b is inserted into the fitting hole of the knuckle portion 7. It is fastened and fixed to the fastening surface of the knuckle portion 7 with a bolt.

In the reducer 10, the flange 11b is fastened and fixed to the knuckle portion 7 such that the lower region 11b-L of the flange 11b faces the rotation direction of the knuckle portion 7. The low region 11b-L of the flange 11b has a low protrusion height from the outer circumferential surface of the case body 11a, so when the knuckle portion 7 rotates with respect to the arm portion 6, the flange 11b does not interact with other surrounding members. Less likely to interfere. The lower region 11b-L of the flange 11b is located at a location to avoid interference with surrounding members. Therefore, a sufficient movable angle of the knuckle portion 7 can be ensured.

As described above, in the reducer 10 (power transmission device) of this embodiment, the outer peripheral surface S1 of the shaft support region 14a of the crankshaft 14 constitutes the inner race surface of the bearing 21. Therefore, the reducer 10 of this embodiment does not require an inner race dedicated to the bearing 21. Therefore, the reducer 10 of this embodiment can support the crankshaft 14 on the first carrier block 13A and the second carrier block 13B with a simple configuration with a small number of parts, and can suppress a rise in product costs. I can do it.

Further, in the reducer 10 of the present embodiment, the inner peripheral surface S2 of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B constitutes the outer race surface of the bearing 21. are doing. Therefore, the reducer 10 of this embodiment does not require an outer race dedicated to the bearing 21. Therefore, when the speed reducer 10 of this embodiment is adopted, the number of parts can be further reduced, and the product cost can be further reduced.

Furthermore, since the reducer 10 of this embodiment uses cylindrical rollers 21a, which are easy to manufacture, instead of conical rollers as the rolling elements of the bearing 21, the product cost can also be reduced from this point of view. In the reducer 10 of this embodiment, the contact angle of the outer circumferential surface S1 (inner race surface) of the shaft support region 14a with respect to the cylindrical roller 21a is set to an angle greater than 0° and less than or equal to 10°. . Therefore, when the reducer 10 of this embodiment is adopted, the differential slip that occurs between the cylindrical rollers 21a and the outer circumferential surface S1 (inner race surface) of the shaft support region 14a during rotation transmission by the crankshaft 14 can be prevented. , it can be set within a range that does not cause any practical problems.

Furthermore, in the reducer 10 of the present embodiment, similarly, the inner circumferential surface S2 (outer race) of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B is cylindrical. The contact angle with respect to the roller 21a is set to be greater than 0° and less than 10°. For this reason, in the reducer 10 of the present embodiment, when rotation is transmitted by the crankshaft 14, a generated Differential slippage can also be kept within a range that does not pose a problem in practice.

Further, in the reducer 10 of the present embodiment, an inner displacement regulating surface 36 that regulates the axially inner displacement of the cylindrical roller 21a is integrally formed on the axially inner portion of the shaft support region 14a of the crankshaft 14. There is. Therefore, there is no need to attach a separate retaining ring to the crankshaft 14 in order to restrict the axially inward displacement of the cylindrical rollers 21a. Therefore, when this configuration is adopted, the number of parts can be reduced and product costs can be further reduced.

Furthermore, the reducer 10 of the present embodiment is provided in the inner regions of the first and second support holes 13Aa-1 and 13Ba-1 of the first carrier block 13A and the second carrier block 13B, and on the axially outer side of the cylindrical rollers 21a. An outer displacement regulating surface 35 is integrally formed to regulate the displacement of the cylindrical roller 21a and apply a preload to the cylindrical roller 21a. Therefore, there is no need to attach a separate retaining ring to the first carrier block 13A or the second carrier block 13B in order to apply preload to the cylindrical roller 21a. Therefore, when this configuration is adopted, it is possible to further reduce the number of parts and further reduce the product cost.

In the reducer 10 of the present embodiment, the hardness of the outer peripheral surface S1 of the shaft support region 14a of the crankshaft 14, the first and second support holes 13Aa-1 of the first carrier block 13A and the second carrier block 13B, The hardness of the inner circumferential surface S2 of 13Ba-1 is set to be equal to the hardness of the outer circumferential surface (contact surface) of the cylindrical roller 21a. Therefore, when power is transmitted by the crankshaft 14, the outer circumferential surface S1 of the shaft support region 14a, the outer circumferential surface (contact surface) of the cylindrical roller 21a, and the inner circumferences of the first and second support holes 13Aa-1 and 13Ba-1 Deformation and damage are unlikely to occur on any of the surfaces S2. Therefore, when the speed reducer 10 of this embodiment is employed, stable rolling of the cylindrical rollers 21a, which are rolling elements, can be maintained over a long period of time.

Note that the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the gist thereof.
For example, in the above embodiment, the speed reducer 10 constitutes a power transmission device, but the power transmission device according to the present invention is not necessarily limited to a speed reducer, and is not limited to a power transmission device that does not have a speed reduction function. It may be.

Further, in the above embodiment, the inner race surface is integrally formed in both the first shaft support region 14a of the crankshaft 14 and the second shaft support region 14a of the crankshaft 14. However, the inner race surface may be integrally formed only on one of the two shaft support regions 14a.
Similarly, in the above embodiment, the outer race surface is integrally formed in both the first support hole 13Aa-1 and the second support hole 13Ba-1, but the first support hole 13Aa-1 and the second support hole The outer race surface may be integrally formed only on either one of 13Ba-1.
Furthermore, although the crankshaft 14 of the above embodiment has a pair of shaft support regions 14a arranged on both sides of the eccentric region 14b in the axial direction, the number of shaft support regions provided on the crankshaft is not limited to two, but may be one. However, there may be three or more.
Furthermore, in the above embodiment, almost the entire inner circumferential surface of the shaft support hole (first support hole 13Aa-1 and second support hole 13Ba-1) constitutes an outer race surface that comes into contact with the cylindrical roller 21a. However, the outer race surface may be formed by a part of the shaft support hole.

10...Reducer 11...Case 13A...First carrier block (first block, support block)
13Aa-1...First support hole (shaft support hole)
13B...Second carrier block (second block, support block)
13Ba-1...Second support hole (shaft support hole)
14...Crankshaft 14a...Shaft support area (first support area, second support area)
14b... Eccentric region 21... Bearing 21a... Cylindrical roller (rolling element)
35...Outer displacement regulating surface 36...Inner displacement regulating surface S1...Outer peripheral surface (inner race surface)
S2...Inner peripheral surface (outer race surface)

Claims (9)

A support block placed inside the case,
a crankshaft having a shaft support region forming an inner race surface on an outer circumferential surface, and an eccentric region disposed adjacent to the shaft support region;
cylindrical rollers that are rolling elements that rotatably support the shaft support region of the crankshaft on the support block;
Equipped with
In the power transmission device, the outer circumferential surface of the shaft support region of the crankshaft is constituted by a tapered surface tapered toward an axial end of the crankshaft. The crankshaft has a first support region and a second support region arranged on both sides of the eccentric region in the axial direction,
The power transmission device according to claim 1, wherein at least one of the first support region and the second support region constitutes the shaft support region. The support block has a shaft support hole that supports the shaft support region,
The power transmission device according to claim 1 or 2, wherein at least a portion of the inner circumferential surface of the shaft support hole constitutes an outer race surface that comes into contact with the rolling element. The power transmission device according to claim 3, wherein the inner circumferential surface of the shaft support hole has a contact angle greater than 0° and less than 10°. The power transmission device according to claim 3 or 4, wherein the inner circumferential surface of the shaft support hole and the contact surface of the rolling element have the same hardness. The power transmission device according to any one of claims 3 to 5, wherein an outer displacement regulating surface for regulating axially outer displacement of the rolling element is integrally formed on the inner periphery of the shaft support hole. The power transmission device according to any one of claims 1 to 6, wherein the inner race surface has a contact angle greater than 0° and less than 10°. The power transmission device according to any one of claims 1 to 7, wherein the outer circumferential surface of the shaft support region and the contact surface of the rolling element have the same hardness. The power transmission device according to any one of claims 1 to 8, wherein the shaft support region has an inner displacement regulating surface that regulates axially inward displacement of the cylindrical roller.

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