CN106402282B

CN106402282B - Eccentric oscillating gear device and method for manufacturing same

Info

Publication number: CN106402282B
Application number: CN201610615632.8A
Authority: CN
Inventors: 中村江児; 和中雄大
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2015-07-31
Filing date: 2016-07-28
Publication date: 2020-10-30
Anticipated expiration: 2036-07-28
Also published as: TW201708737A; TWI698599B; DE102016213887A1; KR20170015193A; JP2017032068A; JP6629000B2; CN106402282A

Abstract

The invention provides an eccentric oscillating gear device capable of increasing load capacity of a journal bearing and a manufacturing method thereof. An eccentric oscillating gear device (1) is provided with: a housing (10) having internal teeth (12) on the inner peripheral side; a gear carrier (20) rotatably held in the housing; a crankshaft (30) for rotatably holding the carrier; and a wobble gear (40) which is held by the crankshaft, has external teeth (42) that mesh with the internal teeth, and wobbles by the crankshaft. The journal portions (31a, 31b) of the crankshaft are held by the carrier via journal bearings (51, 52). Eccentric bodies (32a, 32b) of the crankshaft are held by the oscillating gear via eccentric bearings (61, 62). The outermost radius (Rj) of the rolling elements (51C, 52C) of the journal bearing is greater than the sum distance (Rc) obtained by adding the distance from the central axis of the crankshaft to the anti-eccentric portion of the eccentric body and the thickness dimension of the bearing for the eccentric body inserted into the eccentric body.

Description

Eccentric oscillating gear device and method for manufacturing same

Technical Field

The present invention relates to an eccentric oscillating gear device and a method of manufacturing the same.

Background

As an eccentric oscillating gear device including a housing having internal teeth on an inner peripheral side and an oscillating gear having external teeth meshing with the internal teeth, there is an eccentric oscillating gear device having a structure in which: the oscillating gear oscillates and rotates while having its external teeth meshed with the internal teeth of the housing, and the carrier rotatably supported by the housing rotates in accordance with the oscillating rotation of the oscillating gear.

In such a gear device, the rotation of the housing is restricted. A crankshaft is supported by the carrier, and a wobble gear is supported by the crankshaft. The crankshaft is provided with an eccentric body which is matched with a through hole arranged on the swing gear. The rotation of the eccentric member causes the oscillating gear to oscillate while meshing the external teeth thereof with the internal teeth of the housing. The rotation of the oscillating gear is transmitted to the carrier via the crankshaft. Thereby, the carrier rotates (see, for example, patent documents 1 and 2).

As shown in patent documents 1 and 2, in such a gear device, there are cases where: the carrier includes a base portion having a disk-shaped base plate portion and a shaft portion protruding from one surface of the base plate portion, and a disk-shaped end plate portion fastened in contact with a tip end of the shaft portion of the base portion.

In such a structure, usually, the shaft portion and the end plate portion are fastened by a bolt. The journal portion on one end side of the crankshaft is rotatably held by a journal bearing in a through hole formed in the base plate portion, and the journal portion on the other end side of the crankshaft is rotatably held by a journal bearing in a through hole formed in the end plate portion. As the journal bearing, a tapered roller bearing is generally used.

The tapered roller bearing comprises: an inner ring; an outer ring; a plurality of tapered rolling elements held between the inner ring and the outer ring; and a cage for holding the plurality of rolling elements in a state of being arranged at a predetermined interval. In such a tapered roller bearing, the outer ring is usually configured to be freely separable from the rolling elements. On the other hand, in the state where the outer race is thus separated, the cage and the rolling elements held by the cage are normally held in a state of being attached to the inner race. Specifically, flange portions are formed at one end portion and the other end portion in the axial direction of the inner ring, respectively, and the rolling elements are sandwiched between these flange portions. Thereby, the cage and the rolling elements held by the cage are held in a state of being attached to the inner ring.

The oscillating gear is disposed between the base plate portion and the end plate portion, and an eccentric body of the crankshaft is inserted into a through hole of the oscillating gear between the base plate portion and the end plate portion. Usually, an eccentric bearing is disposed between the eccentric body and the through hole of the oscillating gear. As the bearing for the eccentric body, a cylindrical roller bearing is generally used.

As disclosed in patent documents 1 and 2, in such a gear device, the eccentric body of the crankshaft may be composed of two eccentric bodies, and two oscillating gears may be provided. In this case, one of the two eccentric bodies is rotatably held by one of the two oscillating gears via the eccentric-body bearing. The other eccentric body of the two eccentric bodies is rotatably held by the other gear of the two oscillating gears by means of a bearing for the eccentric body.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-185631

Patent document 2: japanese patent laid-open publication No. 2014-190451

Disclosure of Invention

Problems to be solved by the invention

However, as disclosed in patent documents 1 and 2, in the conventional gear device of this type, the sum of the distance from the central axis of the crankshaft to the reverse eccentric side portion of the eccentric body disposed on the end plate side and the thickness dimension of the bearing for the eccentric body inserted into the eccentric body is larger than the outermost circumferential radius of the rolling elements of the journal bearing disposed between the through hole of the end plate portion and the journal portion of the crankshaft. The reverse eccentric side portion is a portion of the eccentric body on the opposite side of the eccentric side portion, i.e., a portion protruding outward in the radial direction.

Fig. 5 is a diagram illustrating the above dimensional relationship of the conventional gear device. In fig. 5, reference numeral 100 denotes a carrier, and shows a state before a base portion 101 and an end plate portion 102 of the carrier 100 are fastened. Reference numeral 110 denotes a crankshaft, and the crankshaft 110 has two

eccentric bodies

111a and 111b, of which the eccentric body 111b is disposed on the end plate portion 102 side. A cylindrical roller bearing 112 as an eccentric bearing is inserted into the eccentric body 111 b. In fig. 5, a tapered roller bearing 114b, which is a journal bearing in a state where an outer ring is separated, is inserted into a journal portion 113b adjacent to an eccentric body 111b in a crankshaft 110. That is, fig. 5 shows a state in which the inner ring of the tapered roller bearing 114b is inserted into the journal portion 113b, and the cage and the rolling elements held by the cage are held in the inner ring.

In fig. 5, reference sign Rc' denotes an added distance obtained by adding a distance from the central axis of the crankshaft 110 to the anti-eccentric side portion of the eccentric body 111b disposed on the end plate portion 102 side and a thickness dimension of the cylindrical roller bearing (bearing for eccentric) 112 inserted into the eccentric body 111 b. Reference numeral Rj' denotes the outermost radius of the rolling elements of the tapered roller bearing (journal bearing) 114b disposed between the through hole of the end plate 102 and the journal portion 113b of the crankshaft 110. As is clear from the figure, the added distance Rc 'is larger than the outermost peripheral radius Rj' of the rolling element.

As shown in fig. 5, in the configuration having such a dimensional relationship, the cylindrical roller bearing 112 can be inserted into the eccentric body 111b held by the crankshaft 110, and the inner ring in a state where the rolling elements of the tapered roller bearing 114b are held can be inserted into the journal portion 113b of the crankshaft 110. In this state, as shown by an arrow in the figure, the cylindrical roller bearing 112 can be inserted into the through hole of the oscillating gear 120 by passing the oscillating gear 120 having the through hole into which the eccentric body 111b is inserted through the rolling elements of the tapered roller bearing 114 b. Thereafter, the outer ring can be attached to the rolling elements of the tapered roller bearing 114 b. By being able to execute the assembly procedure described above, assembly can be performed efficiently.

However, although this structure can provide advantages in terms of assembly work, the tapered roller bearing 114b as a journal bearing is restricted in its radial dimension, thereby restricting an increase in the load capacity of the bearing. The load capacity of the journal bearing is increased in some cases, for example, in a case where it is desired to increase the eccentric amount of the eccentric body of the crankshaft. That is, when the eccentric amount of the eccentric body of the crankshaft is increased, the force in the radial direction and the thrust direction transmitted from the crankshaft to the carrier is increased. Therefore, in order to properly hold the crankshaft, there are cases where it is desirable to increase the load capacity of the journal bearing.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an eccentric oscillating type gear device and a manufacturing method thereof capable of increasing the load capacity of a journal bearing disposed between a journal portion of a crankshaft and a carrier.

Means for solving the problems

The present invention is an eccentric oscillating gear device including: a housing having internal teeth on an inner peripheral side; a gear carrier rotatably held in the housing; a crankshaft rotatably held by the carrier; and a rocking gear which is held by the crankshaft, has external teeth meshing with the internal teeth, and is rocked by the crankshaft, wherein the crankshaft has a journal portion and an eccentric body provided adjacent to the journal portion, a through hole into which the journal portion is inserted is formed in the carrier, a journal bearing is disposed between the through hole of the carrier and the journal portion, the journal portion is rotatably held by the carrier via the journal bearing, a through hole into which the eccentric body is inserted is formed in the rocking gear, a bearing for the eccentric body is disposed between the through hole of the rocking gear and the eccentric body, the eccentric body is rotatably held by the rocking gear via the bearing for the eccentric body, and an outermost circumferential radius of a rolling element of the journal bearing is larger than a distance from a central axis of the crankshaft to a reverse eccentric side portion of the eccentric body and a thickness of the bearing for the eccentric body inserted into the eccentric body The added distance obtained by adding the degree sizes is large.

According to the eccentric oscillating type gear device of the present invention, the radial dimension of the journal bearing is increased. This can increase the load capacity of the journal bearing disposed between the journal portion of the crankshaft and the carrier.

In the eccentric oscillating type gear device, a transmission gear may be provided in a portion of the journal portion on a side opposite to the eccentric body side.

According to this structure, the transmission gear is supported by the journal bearing after the load capacity is increased. This can ensure a large support rigidity of the transmission gear.

In the eccentric oscillating type gear device, the journal bearing may be a tapered roller bearing.

According to this structure, the tapered roller bearing supports the crankshaft from the axial direction. This can restrict the movement of the crankshaft in the axial direction.

In the above-described eccentric oscillating type gear device, the journal bearing may include: an inner ring mounted to the journal portion; an outer ring mounted on the through hole of the carrier; and a rolling element group including a plurality of rolling elements held between the inner ring and the outer ring, wherein the journal bearing is configured such that the rolling element group is detachably separable from the inner ring.

According to this configuration, in the journal bearing, the rolling element group can be freely detached from the inner ring, and therefore, the change in the assembly procedure increases. This improves the ease of assembly of the gear device.

In the eccentric oscillating type gear device, an outermost peripheral radius of the inner ring of the journal bearing may be smaller than the added distance.

Further, the present invention is a method of manufacturing an eccentric oscillating gear device including: a housing having internal teeth on an inner peripheral side; a gear carrier rotatably held in the housing; a crankshaft rotatably held by the carrier; and a rocking gear held by the crankshaft, having external teeth meshing with the internal teeth, and rocking by the crankshaft, the method for manufacturing the eccentric rocking gear device including: a step of attaching an eccentric body bearing to the eccentric body of the crankshaft; a step of mounting an inner ring of a journal bearing on a journal portion of the crankshaft; a step of inserting the bearing for the eccentric body, which is attached to the eccentric body, into the through hole by moving the oscillating gear from the journal portion side to the eccentric body side so that the inner ring passes through a through hole formed in the oscillating gear; and a step of assembling the rolling element group and the outer ring to the inner ring.

According to the manufacturing method of the present invention, in the eccentric rocking type gear device, even when the outermost peripheral radius of the rolling element of the journal bearing is larger than the added distance obtained by adding the distance from the central axis of the crankshaft to the reverse eccentric side portion of the eccentric body and the thickness dimension of the bearing for the eccentric body inserted into the eccentric body, the gear device can be efficiently manufactured. Therefore, the gear device capable of increasing the load capacity of the journal bearing disposed between the journal portion of the crankshaft and the carrier can be efficiently manufactured.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide an eccentric rocking type gear device capable of increasing the load capacity of a journal bearing disposed between a journal portion of a crankshaft and a carrier.

Drawings

Fig. 1 is a sectional view of an eccentric oscillating gear device according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a journal bearing of the eccentric oscillating gear device of fig. 1.

Fig. 3 is a diagram illustrating a method of manufacturing the eccentric rocking type gear device of fig. 1.

Fig. 4 is a diagram illustrating a method of manufacturing the eccentric rocking type gear device of fig. 1.

Fig. 5 is a diagram illustrating a dimensional relationship of a conventional eccentric rocking gear device.

Description of the reference numerals

1. An eccentric oscillating type gear device; 10. a housing; 12. internal teeth; 20. a gear carrier; 21. a substrate section; 23. a base; 24. an end plate portion; 27. 1 st journal through hole; 28. a 2 nd journal through hole; 30. a crankshaft; 31. a shaft body; 31a, 1 st journal portion; 31b, 2 nd journal part; 32a, 1 st eccentric body; 32b, 2 nd eccentric body; 33. a spur gear; 36a, an eccentric side portion; 36b, reverse eccentric side portion; 38a, an eccentric side portion; 38b, the anti-eccentric side portion; 40. a swing gear; 40a, 1 st oscillating gear; 40b, 2 nd oscillating gear; 42. an outer tooth; 42a, outer tooth 1; 42b, outer tooth 2; 44a, a through hole for the 1 st eccentric body; 44b, a 2 nd eccentric body through hole; 51. 1 st journal bearing; 51A, an inner ring; 51B, an outer ring; 51C, rolling elements; 51D, a holder; 51E, rolling element group; 52. a 2 nd journal bearing; 52A, an inner ring; 52B, an outer ring; 52C, rolling elements; 52D, a holder; 52E, rolling element group; 61. 1 st eccentric bearing; 61A, rolling elements; 61B, a retainer; 62. the 2 nd eccentric body uses the bearing; 62A, a rolling body; 62B, a retainer; l1, central axis; rc, the addition distance; rj, the outermost peripheral radius of the rolling element; rir, outermost peripheral radius of the inner race.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Structure of eccentric oscillation type Gear device)

An eccentric oscillating gear device 1 (hereinafter referred to as a gear device 1) of the present embodiment shown in fig. 1 includes: a housing 10 having internal teeth 12 on an inner peripheral side; a carrier 20 rotatably held in the casing 10; a crankshaft 30 rotatably held by the carrier 20; and a wobble gear 40 that is held by the crankshaft 30, has external teeth 42 that mesh with the internal teeth 12, and wobbles by the crankshaft 30.

The housing 10 has a housing main body 11 formed in a cylindrical shape with both ends open. The internal teeth 12 are provided on the inner peripheral surface of the housing body 11. In the figure, reference symbol L1 denotes a center axis of the housing main body 11, and more specifically, a center axis of an inner peripheral surface of the housing main body 11 provided with the internal teeth 12. Hereinafter, when simply referred to as "axial direction", the direction refers to a direction extending on the central axis L1 or a direction parallel to the central axis L1. A direction perpendicular to the center axis L1 is referred to as a radial direction, and a direction around the center axis L1 is referred to as a circumferential direction.

The internal teeth 12 are formed in pin shapes, and the internal teeth 12 are fitted and attached to a plurality of pin grooves 13 formed along the circumferential direction in the entire inner circumferential surface of the housing main body 11. The internal teeth 12 are arranged such that the longitudinal direction thereof is parallel to the central axis Ll direction. The internal teeth 12 are arranged at equal intervals in the circumferential direction on the inner circumferential surface of the housing body 11, and mesh with the external teeth 42 of the above-described oscillating gear 40.

The carrier 20 includes: a base portion 23 having a disk-shaped substrate portion 21 and a shaft portion 22 protruding from one surface of the substrate portion 21; and a disc-shaped end plate portion 24 fastened in contact with the tip end of the shaft portion 22 of the base portion 23. A plurality of shaft portions 22 are formed in a state of being arranged in the circumferential direction. The end plate 24 abuts against the tip of each shaft 22 and is fastened to each shaft 22. In the illustrated example, the end plate portion 24 and the shaft portion 22 are fastened by a bolt 25 that straddles the end plate portion 24 and the shaft portion 22.

The carrier 20 is rotatably supported on the inner peripheral surface of the case body 11 by a pair of main bearings 26 disposed on the outer peripheral side of the substrate portion 21 and the outer peripheral side of the end plate portion 24. Thereby, the carrier 20 is rotatable about the central axis L1 with respect to the casing 10. In the present embodiment, the main bearing 26 is formed of an angular ball bearing.

The crankshaft 30 includes: a shaft main body 31 having a central axis; two eccentric bodies, namely a 1 st eccentric body 32a and a 2 nd eccentric body 32 b; a spur gear 33 as a transmission gear. In the shaft main body 31, a 1 st journal portion 31a is formed on one end portion side (the substrate portion 21 side), and a 2 nd journal portion 31b is formed on the other end portion side (the end plate portion 24 side).

In the carrier 20, a 1 st journal through hole 27 for inserting a 1 st journal portion 31a is formed in the base plate portion 21, and a 2 nd journal through hole 28 for inserting a 2 nd journal portion 31b is formed in the end plate portion 24. The 1 st journal through hole 27 and the 2 nd journal through hole 28 extend in the axial direction. A 1 st eccentric body 32a and a 2 nd eccentric body 32b are provided in a portion of the shaft main body 31 between the 1 st journal portion 31a and the 2 nd journal portion 31 b.

A 1 st journal bearing 51 is disposed between the 1 st journal through hole 27 and the 1 st journal portion 31 a. Thereby, the 1 st journal portion 31a is rotatably held by the carrier 20 via the 1 st journal bearing 51. Further, a 2 nd journal bearing 52 is disposed between the 2 nd journal through hole 28 and the 2 nd journal portion 31 b. Thereby, the 2 nd journal portion 31b is rotatably held by the carrier 20 via the 2 nd journal bearing 52.

In the present embodiment, the 1 st journal bearing 51 is configured as a tapered roller bearing. The 1 st journal bearing 51 includes: an inner ring 51A attached to the 1 st journal portion 31A; an outer ring 51B attached to the 1 st journal through hole 27; a rolling element group 51E including a plurality of tapered rolling elements 51C held between the inner ring 51A and the outer ring 51B, and a cage 51D holding the plurality of rolling elements 51C in a state where the plurality of rolling elements 51C are arranged at a predetermined interval.

Similarly, in the present embodiment, the 2 nd journal bearing 52 is configured as a tapered roller bearing. The 2 nd journal bearing 52 includes: an inner ring 52A attached to the 2 nd journal portion 31 b; an outer ring 52B attached to the 2 nd journal through hole 28; a rolling element group 52E including a plurality of tapered rolling elements 52C held between the inner ring 52A and the outer ring 52B, and a cage 52D holding the plurality of rolling elements 52C in a state where the plurality of rolling elements 52C are arranged at a predetermined interval.

Fig. 2 shows the 2 nd journal bearing 52 in an enlarged and schematic manner. As shown in fig. 2 (a) and 2 (B), the 2 nd journal bearing 52 of the present embodiment is configured such that the rolling element group 52E can be freely detached from the inner ring 52A. Specifically, in the 2 nd journal bearing 52, after the outer ring 52B is detachably separated from the rolling element group 52E, the rolling element group 52E can be detachably separated from the inner ring 52A.

In the present embodiment, the radial dimension (radius) of the outer peripheral surface of the inner ring 52A gradually decreases from one end portion to the other end portion in the axial direction. A flange portion 52F is formed at an end portion of the inner race 52A on the side where the radial dimension is large in the axial direction. On the other hand, no flange portion is formed at an end portion (an end portion on a side where the radial dimension is small) opposite to the end portion on the side where the flange portion 52F is formed. This enables the rolling element group 52E to be separated from the end of the inner ring 52A on the side where the flange is not formed.

When the rolling element group 52E is separated from the inner ring 52A, the state in which the cage 52D holds the plurality of rolling elements 52C is maintained in the rolling element group 52E. Further, by inserting the rolling element group 52E into the inner ring 52A, the rolling element group 52E can be assembled to the inner ring 52A. In the present embodiment, the 2 nd journal bearing 52 is configured to be detachable and separable from the rolling element group 52E as described above, and the 1 st journal bearing 51 may have a similar configuration.

Returning to fig. 1, a 1 st stopper 29a is provided on the inner peripheral surface of the 1 st journal through hole 27. The 1 st retaining ring 29a abuts against the outer ring 51B of the 1 st journal bearing 51 from the outside in the axial direction (the side opposite to the side of the swing gear 40), and thereby restricts the movement of the 1 st journal bearing 51 to the outside in the axial direction. Similarly, a 2 nd retaining ring 29b is provided on the inner peripheral surface of the 2 nd journal through hole 28. The 2 nd retaining ring 29B abuts against the outer ring 52B of the 2 nd journal bearing 52 from the outside in the axial direction (the side opposite to the side of the swing gear 40), and thereby restricts the movement of the 2 nd journal bearing 52 to the outside in the axial direction.

The 1 st eccentric body 32a and the 2 nd eccentric body 32b in the crankshaft 30 are integrally formed with the shaft main body 31. The 1 st eccentric body 32a and the 2 nd eccentric body 32b are arranged in an axially aligned state. The 1 st eccentric body 32a is disposed adjacent to the 1 st journal portion 31a, and the 2 nd eccentric body 32b is disposed adjacent to the 2 nd journal portion 31 b.

Each of the

eccentric bodies

32a, 32b is formed in a disc shape (or a cylindrical shape). The

eccentric bodies

32a and 32b are eccentric with respect to the shaft main body 31. In detail, in the drawing, reference symbol ac denotes a central axis of the shaft main body 31, reference symbol aca denotes a central axis of the 1 st eccentric body 32a, and reference symbol acb denotes a central axis of the 2 nd eccentric body 32 b. As shown by these axes, the center axis aca of the 1 st eccentric body 32a and the center axis acb of the 2 nd eccentric body 32b are offset from the center axis ac of the shaft main body 31. When viewed along the center axis ac of the shaft main body 31, the center axis aca of the first eccentric body 32a and the center axis acb of the 2 nd eccentric body 32b are symmetrically arranged around the center axis ac of the shaft main body 31.

Reference numeral 36a in the drawing denotes an eccentric side portion of the 1 st eccentric body 32a that is eccentric (protruded) to the outermost side in the direction from the central axis ac of the shaft main body 31 toward the central axis aca of the 1 st eccentric body 32a, and reference numeral 36b denotes an anti-eccentric side portion of the 1 st eccentric body 32a that is located on the opposite side from the eccentric side portion 36 a. Likewise, reference numeral 38a in the drawing denotes an eccentric side portion of the 2 nd eccentric body 32b that is eccentric (protruded) to the outermost side in the direction from the central axis ac of the shaft main body 31 toward the central axis acb of the 2 nd eccentric body 32a, and reference numeral 38b denotes an anti-eccentric side portion of the 2 nd eccentric body 32b that is located on the opposite side from the eccentric side portion 38 a. The

eccentric bodies

32a and 32b are inserted into through holes formed in the swing gear 40, thereby holding the swing gear 40. The details of which are discussed later.

Further, the 2 nd journal portion 31b of the shaft main body 31 protrudes outward in the axial direction from the end plate portion 24 of the carrier 20 via the 2 nd journal bearing 52. The above-mentioned spur gear 33 is fixed to a portion of the 2 nd journal portion 31b that protrudes from the end plate portion 24. That is, the spur gear 33 is provided at a portion of the 2 nd journal portion 31b opposite to the 2 nd eccentric body 32b side. Rotation is transmitted from an input gear not shown to the spur gear 33, whereby the crankshaft 30 is rotated.

In the present embodiment, three 1 st journal through-holes 27 and three 2 nd journal through-holes 28 are formed in the carrier 20, and the three crankshafts 30 are rotatably held by the carrier 20. Therefore, three journal bearings 51, 2 nd journal bearing 52, and spur gear 33 are provided.

Next, the swing gear 40 is composed of a 1 st swing gear 40a and a 2 nd swing gear 40 b. The oscillating gears 40a and 40b are arranged in the axial direction and are disposed in a space formed between the base plate portion 21 and the end plate portion 24 of the carrier 20. The 1 st oscillating gear 40a is disposed on the substrate portion 21 side, and the 2 nd oscillating gear 40b is disposed on the end plate portion 24 side.

The 1 st external tooth 42a of the external teeth 42 is formed on the outer peripheral portion of the 1 st wobble gear 40 a. The 2 nd external teeth 42b of the external teeth 42 are formed on the outer peripheral portion of the 2 nd oscillating gear 40 b. The number of teeth of the 1 st external tooth 42a and the 2 nd external tooth 42b is smaller (for example, one less) than the number of teeth of the internal teeth 12 of the housing 10. As a result, the eccentric rotations of the

eccentric bodies

32a and 32b cause the oscillating gears 40a and 40b to oscillate and rotate relative to the housing 10 while the external teeth 42 thereof mesh with the internal teeth 12.

In the present embodiment, the 1 st oscillating gear 40a is formed with three 1 st eccentric body through holes 44a for inserting the 1 st eccentric body 32a of the crankshaft 30 and a 1 st shaft portion through hole 45a for inserting the shaft portion 22 of the carrier 20. The 2 nd oscillating gear 40b is formed with three 2 nd eccentric through holes 44b for inserting the 2 nd eccentric body 32b of the crankshaft 30 and a 2 nd axial through hole 45b for inserting the axial portion 22 of the carrier 20.

A 1 st eccentric body bearing 61 is disposed between the 1 st eccentric body through hole 44a and the 1 st eccentric body 32 a. Thereby, the 1 st eccentric body 32a is rotatably held by the 1 st oscillating gear 40a via the 1 st eccentric body bearing 61. Further, a 2 nd eccentric bearing 62 is disposed between the 2 nd eccentric through hole 44b and the 2 nd eccentric body 32b, and the 2 nd eccentric body 32b is rotatably held by the 2 nd oscillating gear 40b via the 2 nd eccentric bearing 62.

In the present embodiment, the bearing 61 for the 1 st eccentric body is configured as a cylindrical roller bearing (needle bearing). Specifically, in this example, the 1 st eccentric bearing 61 is configured by a plurality of cylindrical rolling elements 61A and a cage 61B that holds the plurality of rolling elements 61A. Therefore, in a state where the 1 st eccentric body bearing 61 is disposed between the 1 st eccentric body through hole 44a and the 1 st eccentric body 32a, each rolling element 61A approaches or abuts the 1 st eccentric body through hole 44a and approaches or abuts the 1 st eccentric body 32 a.

Similarly, in the present embodiment, the 2 nd eccentric bearing 62 is configured as a cylindrical roller bearing (needle bearing). In this example, the 2 nd eccentric bearing 62 is also configured by a plurality of cylindrical rolling elements 62A and a cage 62B that holds the plurality of rolling elements 62A. Therefore, in a state where the 2 nd eccentric body bearing 62 is disposed between the 2 nd eccentric body through hole 44b and the 2 nd eccentric body 32b, each rolling element 62A approaches or abuts the 2 nd eccentric body through hole 44b and the 2 nd eccentric body 32 b.

Here, in fig. 1, reference sign Rc denotes an added distance obtained by adding a distance from the central axis (ac) of the crankshaft 30 to the anti-eccentric side portion 38b of the 2 nd eccentric body 32b and a thickness dimension of the 2 nd eccentric body bearing 62 inserted into the eccentric body 32 b. Further, reference symbol Rj denotes an outermost peripheral radius (maximum runout radius) of the rolling elements 52C of the 2 nd journal bearing 52 inserted into the 2 nd journal portion 31b of the crankshaft 30. In the present embodiment, the rolling elements 52C are formed in a tapered shape such that the central axis thereof is inclined with respect to the central axis of the 2 nd journal bearing 52. The outer peripheral edge of the end portion of the rolling element 52C on the side of the major diameter extends outward in the radial direction with respect to the center axis of the 2 nd journal bearing 52. The outermost radius Rj is a distance from the center axis of the 2 nd journal bearing 52 to the outer peripheral edge of the end of the rolling element 52C on the side of the larger diameter.

As is apparent from fig. 1, in the present embodiment, the outermost circumferential radius Rj of the rolling elements 52C of the 2 nd journal bearing 52 is greater than the added distance Rc. In addition, reference numeral Rir in the figure denotes the outermost peripheral radius of the inner ring 52A of the 2 nd journal bearing 52. The outermost peripheral radius Rir of the inner race 52A is less than the added distance Rc. In the present embodiment, the outermost circumferential radius of the rolling elements 51C of the 1 st journal bearing 51 is also larger than the sum of the distance from the central axis of the crankshaft 30 to the anti-eccentric portion 36b of the 1 st eccentric body 32a and the thickness of the 1 st eccentric body bearing 61 inserted into the eccentric body 32 a.

In the gear device 1 having the above-described configuration, when torque from a motor or the like, not shown, is transmitted to the spur gear 33, the crankshaft 30 rotates. At this time, the 1 st eccentric body 32a and the 2 nd eccentric body 32b of the crankshaft 30 eccentrically rotate, respectively. When the

eccentric bodies

32a, 32b eccentrically rotate, the respective swing gears 40a, 40b revolve (revolve) around the central axis line of the carrier 20. At this time, the oscillating gears 40a and 40b rotate relative to the housing 10 while the external teeth 42 thereof mesh with the internal teeth 12 of the housing 10. As a result, the carrier 20 supporting the swing gears 40a and 40b via the crankshaft 30 rotates relative to the casing 10.

Such a gear device 1 can be used as a reduction gear for a revolving unit such as a revolving body and an arm joint of a robot, a revolving unit of various machine tools, and the like. As a specific example, by fixing the housing 10 to the base of the robot and coupling the carrier 20 to the revolving unit of the robot, the revolving unit can be rotated with high torque with respect to the base and the rotation of the revolving unit can be controlled with high accuracy.

(method of manufacturing eccentric oscillating gear device)

Next, a method of manufacturing the gear device 1 will be described with reference to fig. 3 and 4.

In the method of manufacturing the gear device 1 according to the present embodiment, first, as shown in fig. 3, the assembly is performed until the crankshaft 30 is erected and placed on the base portion 23 of the work surface. At this time, first, the base 23 of the carriage 20 is placed on the work surface so that the base plate 21 of the base 23 abuts against the work surface. The 1 st stopper 29a is provided on the inner peripheral surface of the 1 st journal through hole 27 of the substrate portion 21.

Next, the 1 st eccentric body bearing 61 is inserted and attached to the 1 st eccentric body 32a of the crankshaft 30 in a state separated from the base 23, and the 2 nd eccentric body bearing 62 is inserted and attached to the 2 nd eccentric body 32 b. The 1 st eccentric bearing 61 is inserted into the 1 st eccentric through hole 45a of the 1 st oscillating gear 40a, and the 1 st oscillating gear 40a is held by the crankshaft 30.

Next, the 1 st journal bearing 51 is inserted and mounted to the 1 st journal portion 31a of the crankshaft 30. The 1 st journal bearing 51 is attached to the 1 st journal portion 31A in a state where the inner ring 51A, the outer ring 51B, and the rolling element group 51E are integrated. In addition, only the inner race 52A of the 2 nd journal bearing 52 is inserted and mounted to the 2 nd journal portion 31b of the crankshaft 30.

Next, the 1 st journal bearing 51 held by the crankshaft 30 is inserted into the 1 st journal through hole 27 of the base plate portion 21, and the outer race 51B thereof is press-fitted into a state of abutting against the 1 st retaining ring 29 a. Thereby, the state shown in fig. 3 is set.

Next, as shown in fig. 3 and 4, the 2 nd oscillating gear 40b is moved from the 2 nd journal portion 31b side to the 2 nd eccentric body 32b side so that the inner ring 52A of the 2 nd journal bearing 52 passes through the 2 nd eccentric body through hole 44b formed in the 2 nd oscillating gear 40b, and the 2 nd eccentric body bearing 62 attached to the 2 nd eccentric body 32b is inserted into the 2 nd eccentric body through hole 44 b.

Thereafter, as shown in fig. 4, the rolling element group 52E is assembled to the inner ring 52A of the 2 nd journal bearing 52, and the outer ring 52B is assembled to the rolling element group 52E. In the illustrated example, the outer ring 52B of the 2 nd journal bearing 52 is inserted into the 2 nd journal through hole 28 of the end plate portion 24. Therefore, the outer ring 52B is assembled to the rolling element group 52E while being held by the end plate portion 24. After that, the assembly work is completed by fastening the end plate portion 24 and the shaft portion 22 of the base portion 23 with the bolt 25. Thereby, the gear device 1 is manufactured.

(Effect)

According to the gear device 1 of the present embodiment described above, the outermost peripheral radius Rj of the rolling elements 52C of the 2 nd journal bearing 52 is larger than the added distance Rc obtained by adding the distance from the central axis of the crankshaft 30 to the reverse eccentric side portion 38b of the 2 nd eccentric body 32b and the thickness dimension of the 2 nd eccentric body bearing 62 inserted into the eccentric body 32 b. According to this structure, the radial dimension of the 2 nd journal bearing 52 is increased. The same applies to the 1 st journal bearing 51. This can increase the load capacity of the

journal bearings

51 and 52 disposed between the

journals

31a and 31b of the crankshaft 30 and the carrier 20.

In addition, a spur gear 33 as a transmission gear is provided at a portion of the 2 nd journal portion 31b of the crankshaft 30 inserted with the 2 nd journal bearing 52, the portion being opposite to the 2 nd eccentric body 32b side. Accordingly, the spur gear 33 is supported by the 2 nd journal bearing 52 having an increased load capacity, and therefore, the support rigidity of the spur gear 33 can be secured to a large extent.

The

journal bearings

51 and 52 are tapered roller bearings, and therefore support the crankshaft 30 from the axial direction. This can restrict the movement of the crankshaft 30 in the axial direction.

In addition, the 2 nd journal bearing 52 includes: an inner ring 52A attached to the 2 nd journal portion 31 b; an outer ring 52B attached to the 2 nd journal through hole 28 of the carrier 20; the 2 nd journal bearing 52 is configured to include a rolling element group 52E including a plurality of rolling elements 52C held between the inner ring 52A and the outer ring 52B, and to be detachable from the inner ring 52A and to separate the rolling element group 52E. Accordingly, the assembling variability is increased, and the assembling property of the gear device 1 can be improved.

In the manufacturing method of the present embodiment, as described above, the following steps are performed: a step of attaching the 2 nd eccentric body bearing 62 to the 2 nd eccentric body 32b of the crankshaft 30; a step of attaching the inner ring 52A of the 2 nd journal bearing 52 to the 2 nd journal portion 31b of the crankshaft 30; a step of moving the 2 nd oscillating gear 40b from the 2 nd journal portion 31b side to the 2 nd eccentric body 32b side so that the inner ring 52A passes through the 2 nd eccentric body through hole 44b formed in the 2 nd oscillating gear 40b, and inserting the 2 nd eccentric body bearing 62 into the 2 nd eccentric body through hole 44 b; and a step of assembling the rolling element group 52E and the outer ring 52B to the inner ring 52A.

According to such a manufacturing method, even when the outermost peripheral radius Rj of the rolling elements 52C of the 2 nd journal bearing 52 is larger than the added distance Rc obtained by adding the distance from the central axis of the crankshaft 30 to the anti-eccentric portion 38b of the 2 nd eccentric body 32b and the thickness dimension of the 2 nd eccentric bearing 62 inserted into the eccentric body 32b as in the gear device 1 of the present embodiment, the gear device 1 can be efficiently manufactured.

That is, in the case of the structure in which the outermost peripheral radius Rj of the rolling elements 52C of the 2 nd journal bearing 52 is greater than the added distance Rc, the following assembly procedure is also conceivable: after the 2 nd oscillating gear 40b is attached to the 2 nd eccentric bearing 62, the 2 nd journal bearing 52 is attached to the 2 nd journal portion 31b of the crankshaft 30, and then the 2 nd journal bearing 52 is inserted into the 2 nd journal through hole 28 of the end plate portion 24 on the crankshaft 30. However, such an assembly sequence is relatively labor and time consuming. In contrast to such an assembly procedure, the manufacturing method of the present embodiment performs the following steps: the 2 nd oscillating gear 40b is moved from the 2 nd journal portion 31b side to the 2 nd eccentric body 32b side so that the inner ring 52A passes through the 2 nd eccentric through hole 44b formed in the 2 nd oscillating gear 40b, and the 2 nd eccentric bearing 62 is inserted into the 2 nd eccentric through hole 44 b. This can simplify the assembly procedure, and therefore, the gear device 1 can be efficiently manufactured. Therefore, the gear device 1 capable of increasing the load capacity of the

journal bearings

51, 52 can be efficiently manufactured.

In the present embodiment, the outermost peripheral radius Rir of the inner race 52A of the 2 nd journal bearing 52 is smaller than the added distance Rc. Accordingly, the step of moving the 2 nd oscillating gear 40b from the 2 nd journal portion 31b side to the 2 nd eccentric body 32b side so that the inner ring 52A passes through the 2 nd eccentric body through hole 44b formed in the 2 nd oscillating gear 40b can be reliably performed. Therefore, the assembling work can be smoothly performed.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the example in which the gear device 1 is provided with three crankshafts 30 has been described, but the number of crankshafts 30 is not particularly limited.

For example, in the above-described embodiment, in the 2 nd journal bearing 52, the flange portion 52F is formed at the end portion on the side where the radial dimension in the axial direction of the inner race 52A is large, and the flange portion is not formed at the end portion (the end portion on the side where the radial dimension is small) of the inner race 51A on the side opposite to the end portion on the side where the flange portion 52F is formed. Thereby, the rolling element group 52E can be separated from the end portion of the inner ring 52A on the side where the flange portion is not formed. However, the rolling element group 52E may be separated from the inner ring 52A by forming flange portions at both axial end portions of the inner ring 52A and deforming the flange portion at the end portion on the side where the radial dimension of the inner ring 52A is small.

Claims

1. An eccentric oscillating gear device comprising:

a housing having internal teeth on an inner peripheral side;

a gear carrier rotatably held in the housing;

a crankshaft rotatably held by the carrier; and

a wobble gear held by the crankshaft, having external teeth meshing with the internal teeth, and being wobbled by the crankshaft,

the crankshaft has a journal portion and an eccentric body disposed adjacent to the journal portion,

the carrier is formed with a through hole for inserting the journal portion,

a journal bearing is disposed between the through hole of the carrier and the journal portion,

the journal portion is rotatably held to the carrier by the journal bearing,

a through hole for inserting the eccentric body is formed in the swing gear,

an eccentric body bearing is disposed between the through hole of the swing gear and the eccentric body,

the eccentric body is rotatably held to the oscillating gear by means of the eccentric body bearing,

it is characterized in that the preparation method is characterized in that,

the journal bearing has: an inner ring mounted to the journal portion; an outer ring mounted on the through hole of the carrier; a rolling element group including a plurality of rolling elements held between the inner ring and the outer ring, wherein the journal bearing is configured such that the rolling element group is detachably separable from the inner ring,

an outermost circumferential radius of the rolling element of the journal bearing is larger than an added distance obtained by adding a distance from a central axis of the crankshaft to a reverse eccentric side portion of the eccentric body and a thickness dimension of the bearing for the eccentric body inserted into the eccentric body, and the outermost circumferential radius of the inner ring of the journal bearing is smaller than the added distance.

2. The eccentric oscillating gear device according to claim 1,

a transmission gear is provided at a portion of the journal portion on a side opposite to the side of the eccentric body.

3. The eccentric oscillating gear device according to claim 1 or 2,

the journal bearing is a tapered roller bearing.

4. A method of manufacturing an eccentric oscillating gear device, the eccentric oscillating gear device comprising: a housing having internal teeth on an inner peripheral side; a gear carrier rotatably held in the housing; a crankshaft rotatably held by the carrier; a wobble gear held by the crankshaft, having external teeth meshing with the internal teeth, and being wobbled by the crankshaft,

the method for manufacturing the eccentric oscillating gear device comprises the following steps:

a step of attaching an eccentric body bearing to the eccentric body of the crankshaft;

a step of mounting an inner ring of a journal bearing on a journal portion of the crankshaft;

a step of inserting the bearing for the eccentric body, which is attached to the eccentric body, into the through hole by moving the oscillating gear from the journal portion side to the eccentric body side so that the inner ring passes through a through hole formed in the oscillating gear;

and a step of assembling the rolling element group and the outer ring to the inner ring,

the outermost peripheral radius of the inner ring of the journal bearing is smaller than an added distance obtained by adding a distance from a central axis of the crankshaft to a reverse eccentric side portion of the eccentric body and a thickness dimension of the bearing for the eccentric body inserted into the eccentric body.