CN107859713B

CN107859713B - Gear device

Info

Publication number: CN107859713B
Application number: CN201710717179.6A
Authority: CN
Inventors: 志津庆刚
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2016-09-21
Filing date: 2017-08-21
Publication date: 2021-04-09
Anticipated expiration: 2037-08-21
Also published as: CN107859713A; JP2018048702A; JP6723652B2

Abstract

The invention aims to further promote the weight reduction of a gear device while inhibiting the reduction of strength. A gear device (12) of the present invention includes: an internal gear (16) provided to the housing (14); an external gear (21) that meshes with the internal gear; a carrier (31) disposed on the axial side of the external gear; a main bearing (41) disposed between the housing and the wheel carrier; and a plurality of column members (33) connected to the carrier and penetrating the external gear, wherein recesses (36) are provided between the column members on a surface (31E) of the carrier facing the external gear, the recesses overlapping the main bearing when viewed in the radial direction, and the recesses do not overlap the line of action (F1) of the main bearing.

Description

Gear device

The present application claims priority based on japanese patent application No. 2016-. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a gear device.

Background

Patent document 1 discloses an eccentric oscillating type gear device. The gear device is provided with: an inner gear provided to the housing; and an external gear engaged with the internal gear. A carrier is disposed on an axial side portion of the external gear, and a main bearing is disposed between the housing and the carrier. The carrier is connected to a plurality of column members that penetrate the external gear.

Patent document 1: japanese laid-open patent publication No. 2006-263878

However, the gear device having the structure in which the plurality of column members penetrating the external gear are coupled to the carrier as described in patent document 1 has the following problems: it is difficult to achieve both suppression of a decrease in strength and weight reduction of the device.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to further promote weight reduction of a gear device while suppressing a decrease in strength.

The present invention solves the above problems by a gear device including: a housing; an inner gear provided to the housing; an outer gear engaged with the inner gear; a carrier disposed on an axial side portion of the external gear; a main bearing disposed between the housing and the wheel carrier; and a plurality of column members connected to the carrier and penetrating the external gear, wherein a recess is provided between the column member and the column member on a surface of the carrier facing the external gear, the recess overlapping the main bearing when viewed in a radial direction, and the recess does not overlap a line of action of the main bearing.

In such a gear device, if a hollow portion is formed in a member or the thickness of the member is made thin unnecessarily to further promote weight reduction, the strength of the device is reduced. In the present invention, a recessed portion is formed between the column member and the column member on the surface of the carrier facing the external gear. The concave portion overlaps the main bearing when viewed in the radial direction, but the concave portion does not overlap the line of action of the main bearing.

By forming the recessed portion satisfying such a condition on the surface of the carrier facing the external gear, it is possible to more effectively reduce the weight of the carrier while suppressing a decrease in the strength of the carrier, and further to further promote the weight reduction of the gear device.

According to the present invention, it is possible to further promote weight reduction of the gear device while suppressing a decrease in strength.

Drawings

Fig. 1 is an overall cross-sectional view of a gear device according to an example of the embodiment of the present invention.

Fig. 2 is an enlarged sectional view of a main portion of fig. 1.

Fig. 3(a) is a front view of a single 1 st wheel carrier of the gear device of fig. 1, fig. 3(B) is a sectional view taken along the line of arrows iii-iiib of fig. 3(a), and fig. 3(C) is a sectional view taken along the line of arrows iii-iiic of fig. 3 (a).

Fig. 4 is a main-part cross-sectional view of a gear device according to another embodiment of the present invention.

Fig. 5 is a side view of the gear arrangement of fig. 4.

In the figure: 12-gear unit, 14-housing, 16-internal gear, 21-external gear 1, 31-first carrier, 31E-face opposite to external gear 1, 33-internal pin (column part), 41-first main bearing, 36-recess, 37-auxiliary recess, F1-1 st line of action.

Detailed Description

Hereinafter, a gear device according to an example of an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is an overall cross-sectional view of a gear device according to an example of the embodiment of the present invention.

The gear device 12 includes: a housing 14; an internal gear 16 provided in the housing 14; and a 1 st external gear 21 meshed with the internal gear 16. The 1 st carrier 31 is disposed on the input side (axial side portion) of the 1 st external gear 21 in the axial direction. The 1 st main bearing 41 is disposed between the housing 14 and the 1 st carrier 31. A plurality of inner pins 33 (column members) penetrating the 1 st external gear wheel 21 are coupled to the 1 st carrier 31. A recess 36 is provided between the inner pin 33 and the inner pin 33 on the surface 31E of the 1 st carrier 31 facing the 1 st external gear wheel 21. The recess 36 overlaps the 1 st main bearing 41 as viewed in the radial direction. However, the recess 36 does not overlap the 1 st line of action F1 of the 1 st main bearing 41.

Hereinafter, a specific configuration of the gear device 12 will be described in more detail.

The 1 st external gear 21 and the 2 nd external gear 22 of the present gear device 12 internally mesh with the internal gear 16 while oscillating. The reason why the internal gear 16 has two systems of external gears (i.e., the 1 st external gear 21 and the 2 nd external gear 22) is to secure a larger transmission capacity and suppress torque variation due to hunting as much as possible.

The gear device 12 includes a crankshaft 38 for rotating the 1 st external gear 21 and the 2 nd external gear 22 in an oscillating manner. The crankshaft 38 is disposed at the center in the radial direction of the gear device 12 (concentric with the axial center C16 of the internal gear 16). The crankshaft 38 has a large-diameter hollow portion 38P penetrating in the axial direction and is formed in a cylindrical shape, and a screw hole 38T is formed in an axial end portion 38E of the crankshaft 38. A power input member (not shown) for inputting power of the drive system to the gear device 12 can be coupled to the crankshaft 38 via the screw hole 38T. That is, the crankshaft 38 constitutes an input shaft of the present gear device 12.

The crankshaft 38 integrally includes a 1 st eccentric body 51 for oscillating the 1 st external gear 21 and a 2 nd eccentric body 52 for oscillating the 2 nd external gear 22. The 1 st eccentric element 51 is externally fitted with a 1 st external gear 21 via a 1 st eccentric element bearing 61. The 2 nd external gear 22 is externally fitted to the 2 nd eccentric body 52 via a 2 nd eccentric body bearing 62. The eccentric amounts of the 1 st eccentric body 51 and the 2 nd eccentric body 52 with respect to the crankshaft 38 are the same. In order to maintain the balance of the oscillation of the 1 st and 2 nd

external gears

21 and 22, the 1 st axial center C51 of the 1 st eccentric body 51 and the 2 nd axial center C52 of the 2 nd eccentric body 52 are eccentric with a phase difference of 180 degrees from each other (the direction of eccentricity is opposite).

The 1 st external gear 21 and the 2 nd external gear 22 internally mesh with the internal gear 16. In this embodiment, the internal gear 16 includes: an internal gear body 16A integrated with the housing 14; pin grooves 16B formed in the inner periphery of the internal gear body 16A in the axial direction; and a cylindrical internal gear pin 16C which is rotatably assembled in the pin groove 16B and constitutes internal teeth of the internal gear 16. The number of inner teeth of the internal gear 16 (the number of inner pins 16C) is slightly larger than the number of outer teeth of the 1 st external gear 21 and the 2 nd external gear 22 (in this example, only 1 more).

The 1 st carrier 31 is disposed on the input side (axial side portion) of the 1 st external gear 21 in the axial direction. A 2 nd carrier 32 is disposed on the output side of the 2 nd external gear 22 in the axial direction. A plurality of inner pins (column members) 33 penetrating the 1 st external gear 21 and the 2 nd external gear 22 are coupled to the 1 st carrier 31 and the 2 nd carrier 32.

More specifically, each inner pin 33 integrally protrudes from the 2 nd carrier 32 (is initially coupled to the 2 nd carrier 32 from the same material as the 2 nd carrier 32). On the other hand, inner pin recesses 31A are formed in the 1 st carrier 31 at positions corresponding to the inner pins 33, and the tip end portions 33A of the inner pins 33 are fitted into the respective inner pin recesses 31A. The inner pin 33 is coupled to the 1 st carrier 31 by an inner pin bolt 80 inserted from a side surface 31G of the 1 st carrier 31 on the opposite side from the 1 st external gear. As a result, the 1 st carrier 31 and the 2 nd carrier 32 are coupled together via the column member (i.e., the inner pin 33), and integrally operate as a large carrier body. Further, reference numeral 31H denotes a through hole through which the inner pin bolt 80 is inserted.

On the other hand, a plurality of 1 st through-holes 21A are formed in the 1 st external gear 21 of the gear device 12 at positions offset from the 1 st axial center C21. A plurality of 2 nd through holes 22A are formed in the 2 nd external gear 22 at positions offset from the 2 nd axial center C22. The inner pin 33 penetrates the 1 st through hole 21A and the 2 nd through hole 22A. An inner roller 34 for facilitating sliding is fitted around the outer periphery of the inner pin 33.

The inner roller 34 contacts a part of the inner circumference of the 1 st through-hole 21A and the 2 nd through-hole 22A. The inner diameters of the 1 st through hole 21A and the 2 nd through hole 22A are larger than the outer diameter of the inner roller 34 by an amount corresponding to twice the eccentric amount of the 1 st eccentric body 51 and the 2 nd eccentric body 52, respectively. Since the inner pin 33 penetrates through the 1 st external gear 21 and the 2 nd external gear 22, the 1 st carrier 31 and the 2 nd carrier 32 coupled to the inner pin 33 operate in synchronization with the rotation of the 1 st external gear 21 and the 2 nd external gear 22.

The 1 st main bearing 41 is disposed between the housing 14 and the 1 st carrier 31. A 2 nd main bearing 42 is disposed between the casing 14 and the 2 nd carrier 32. In the gear device 12, each of the 1 st main bearing 41 and the 2 nd main bearing 42 is constituted by an angular ball bearing assembled in a back-to-back manner.

The 1 st main bearing 41 has: the 1 st rolling element 41A is constituted by a ball; a 1 st inner ring 41B integrated with the 1 st carrier 31 (made of the same material as the 1 st carrier 31); a separate 1 st outer race 41C (made of a different component than the housing 14); and a 1 st cage 41D for holding the 1 st rolling element 41A.

Since the 1 st main bearing 41 according to the present embodiment is formed of an angular ball bearing, the 1 st contact angle θ 1 of the 1 st main bearing 41 is not 0 degrees, and in this example, the 1 st contact angle θ 1 is set to 40 degrees. Here, the 1 st contact angle θ 1 of the 1 st main bearing 41 means: "an angle formed by a plane (the 1 st radial plane P1) perpendicular to the axial center C41 of the 1 st main bearing 41 and a 1 st action line F1 of a resultant force of forces transmitted to the 1 st rolling element 41A by the 1 st inner ring 41B and the 1 st outer ring 41C" (JIS B0104). In other words, the 1 st line of action F1 of the 1 st main bearing 41 of the present gear device 12 is inclined at an angle of 40 degrees equal to the 1 st contact angle θ 1 with respect to the 1 st radial plane P1 and extends in a direction from all of the 1 st rolling elements 41A toward the outside of the gear device 12 (a direction away from the 1 st radial plane P1).

The 2 nd main bearing 42 also has: a 2 nd rolling element 42A formed of a ball; a 2 nd inner race 42B integrated with the 2 nd carrier 32; a separate 2 nd outer ring 42C; and a 2 nd retainer 42D for retaining the 2 nd rolling element 42A. The 2 nd contact angle θ 2 of the 2 nd main bearing 42 is set to 40 degrees. That is, the 2 nd line of action F2 of the 2 nd main bearing 42 is inclined at an angle of 40 degrees equal to the 2 nd contact angle θ 2 with respect to the 2 nd radial plane P2 and extends in a direction from all of the 2 nd rolling elements 42A toward the outside of the gear device 12 (a direction away from the 2 nd radial plane P2).

In the gear device 12, a spot facing space 31B for accommodating a head 80A of an inner pin bolt 80 for coupling the inner pin 33 to the 1 st carrier 31 is formed in a side surface 31G of the 1 st carrier 31 on the side opposite to the 1 st external gear. The spot-facing space 31B is circular, and an inner pin bolt 80 is formed with the spot-facing space 31B. That is, the spot-facing spaces 31B are formed at positions corresponding to the eight inner pins 33 on the side surface 31G of the 1 st carrier 31 on the side opposite to the 1 st external gear, and eight spot-facing spaces 31B are formed in total.

The crankshaft 38 is supported by the 1 st carrier 31 and the 2 nd carrier 32. That is, the 1 st crank bearing 71 is disposed between the crankshaft 38 and the 1 st carrier 31. A 2 nd crankshaft bearing 72 is disposed between the crankshaft 38 and the 2 nd carrier 32. In the gear device 12, the 1 st crank bearing 71 and the 2 nd crank bearing 72 are each formed by a ball bearing having a contact angle of 0 degrees.

The housing 14 is formed with a flange portion 14B. The flange portion 14B is formed with a plurality of coupling through-holes 14A for bolt coupling to the 1 st target member (for example, a front arm of a robot not shown). The 2 nd wheel carrier 32 is formed with a plurality of screw holes 32T for bolt-coupling to the 2 nd target member (for example, a rear arm of a robot not shown).

Here, fig. 2 is an enlarged sectional view of a main portion of fig. 1, fig. 3(a) is a front view showing a structure of a single 1 st wheel carrier 31, fig. 3(B) is a sectional view taken along an arrow iii-iiib of fig. 3(a), and fig. 3(C) is a sectional view taken along an arrow iii-iiic of fig. 3 (a).

The gear device 12 has a recess 36 between an inner pin 33 (a plurality of inner pins are present) and an inner pin 33 on a surface 31E of the 1 st carrier 31 facing the 1 st external gear 21. Here, "the recess 36 is provided between the inner pin 33 and the inner pin 33" means that "in a cross section (a cross section in fig. 3 a) perpendicular to the axial center C31 of the 1 st carrier 31, a line L (C31-C31A) connecting the axial center C31 of the 1 st carrier 31 (i.e., the axial center C16 of the ring gear 16) and the center C33 of the inner pin 33 (i.e., the center C31A of the inner pin recess 31A) does not overlap the recess 36". In the gear device 12, the center C33 of the inner pin 33 coincides with the center C31H of the through hole 31H through which the inner pin bolt 80 is inserted and the center C31B of the spot facing space 31B.

In this example, eight inner pins 33 are provided in the circumferential direction, and eight recesses 36 are provided between each inner pin 33 and the inner pin 33, for a total of eight. The recess 36 overlaps the 1 st main bearing 41 by δ (36-41C) as viewed in the radial direction. In the gear device 12, the recess 36 is formed at the same position (on the same circumference) as the inner pin (column member) 33 in the radial direction. Specifically, the center C31A of the inner pin recess 31A and the center C36 of the recess 36 are on the same circumference centered on the shaft center C31 of the 1 st carrier 31. In addition, the position of the recess 36 in the radial direction does not necessarily have to be the same as the position of the inner pin 33 (inner pin recess 31A) in the radial direction.

Here, in the present invention, "the concave portion overlaps the main bearing when viewed in the radial direction" means "the concave portion overlaps at least a part of the main bearing when viewed in the radial direction". In this case, the main bearing includes concepts of an outer ring and an inner ring in addition to concepts of rolling elements. Specifically, for example, when the inner ring or the outer ring of the main bearing is formed of an independent member as in the 1 st outer ring 41C of the present gear device 12, the overlapping state is determined based on whether or not the recess portion overlaps with a part of the inner ring or the outer ring. For example, in the case where the inner ring and the outer ring of the main bearing are not formed of separate members (in the case of being integrated with a carrier or a housing) as in the 1 st inner ring 41B of the gear device 12, the overlapping state is determined by considering the width in the axial direction of the rolling elements as the width in the axial direction of the main bearing.

In the present gear device 12, the recess 36 and the 1 st main bearing 41 overlap by δ (36-41C) in the 1 st outer ring 41C when viewed in the radial direction. However, the recess 36 does not overlap the 1 st line of action F1 of the 1 st main bearing 41. Specifically, the recess 36 is spaced apart from the 1 st line of action F1 by a distance L (36-F1).

In the gear device 12, the concave portion 36 is provided with an auxiliary concave portion 37 so as to be continuous with the concave portion 36. Here, the "auxiliary recess" means: "a portion which is provided continuously from an end portion of the recess portion on the side opposite to the external gear and in which the cross-sectional area decreases with distance from the external gear is larger than that of the recess portion". The "portion 37 provided continuously from the recessed portion 36" of the present gear device 12 is provided continuously with the recessed portion 36 at the end portion of the recessed portion 36 on the side opposite to the 1 st external gear. The cross-sectional area of the portion of the recessed portion 36 is not reduced, and the cross-sectional area of the "portion 37 provided continuously from the recessed portion 36" is reduced as it is farther from the 1 st external gear 21. That is, the ratio of the sectional area decrease with distance from the 1 st external gear 21 is larger than that of the concave portion 36. Therefore, "the portion 37 provided continuously from the recess 36" corresponds to "an auxiliary recess" in the present invention.

In the gear device 12, the 1 st line of action F1 of the 1 st main bearing 41 does not overlap with the recess 36, does not overlap with the auxiliary recess 37 (the portion closest to the 1 st line of action F1), and has a distance L (36-F1). That is, the 1 st acting line F1 of the 1 st main bearing 41 does not overlap with both the concave portion 36 and the auxiliary concave portion 37.

Specifically, the auxiliary recess 37 of the gear device 12 corresponds to a portion formed by the tip of a drill when the recess 36 is formed by the drill not shown. However, in the present invention, the formation of the concave portion 36 is not limited to the post-processing by the drill, and may be an originally-provided concave portion formed by forging, casting, or the like. In other words, in the present invention, the auxiliary recess 37 is not essential, and the auxiliary recess 37 may not be provided.

The cross-sectional shape of the concave portion 36 (the cross-sectional shape perpendicular to the axial center C16 of the internal gear 16: the cross-sectional shape in fig. 3 a) is not limited to a circular shape. For example, the cross-sectional shape (cross-sectional shape perpendicular to the axis) of the recess 36 may be an oval or a rectangle, or may be formed in a drum shape in which the dimension in the circumferential direction of the center portion in the radial direction is smaller than the dimension in the circumferential direction of the outer and inner portions in the radial direction, corresponding to the shape of the adjacent inner pins 33 or inner rollers 34. In the case where a plurality of recesses 36 are formed, the shapes of the respective recesses 36 may be different from each other.

The number of the recesses 36 is not limited to the number of the recesses 36 provided between the inner pins 33. For example, two recesses 36 arranged in the radial direction may be formed between the inner pins 36, or the recesses 36 may not be formed between a part of the inner pins 33 and the inner pins 33. Further, only one concave portion 36 may be formed between a specific (not a plurality of) inner pins 33 and the inner pin 33. In the gear device 12, the cross-sectional area of the cross section of the recess 36 perpendicular to the axis is constant in the axial direction, but is not limited to this, and for example, the cross-sectional area may be formed in a shape that gradually decreases as it goes away from the surface 31E facing the 1 st external gear 21.

In the gear device 12, the recess 36 is spaced apart from the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41 by a distance L (36-C41A) in a radial direction, and does not overlap with the center C41A in the radial direction.

However, when viewed in the radial direction, the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41 overlaps the auxiliary concave portion 37. In other words, the auxiliary recess 37 extends δ (37-C41A) further to the side opposite to the 1 st external gear than the center C41A of the 1 st rolling element 41A.

As shown in fig. 3(a) to 3(C), the gear device 12 further includes a 2 nd recessed portion 36Sp between the inner pin 33 and the inner pin 33, and a through hole 31P penetrating the 1 st carrier 31 is formed in the 2 nd recessed portion 36Sp so as to be continuous with the 2 nd recessed portion 36 Sp. The cross-sectional area of the through-hole 31P is smaller than the cross-sectional area of the 2 nd recess 36 Sp. In other words, the gear device 12 ″ has the 2 nd concave portion 36Sp between the inner pin 33 and the inner pin 33, and the gear device 12 further has the through hole 31P communicating with the 2 nd concave portion 36Sp, having a sectional area smaller than that of the 2 nd concave portion 36Sp, and penetrating the 1 st carrier 31 ″. In the gear device 12, the through-hole 31P serves as a grease discharge port. In this example, the shape of the 2 nd concave portion 36Sp when the through-hole 31P is not formed is the same as the shape of the concave portion 36.

Next, the operation of the gear device 12 will be described.

When the crankshaft (input shaft) 38 is rotated by driving of a motor or the like (not shown), the 1 st eccentric body 51 and the 2 nd eccentric body 52 integrated with the crankshaft 38 rotate together with the crankshaft 38. When the 1 st eccentric body 51 and the 2 nd eccentric body 52 rotate, the 1 st external gear 21 and the 2 nd external gear 22 assembled via the 1 st eccentric body bearing 61 and the 2 nd eccentric body bearing 62 perform an oscillating rotation. The 1 st external gear 21 and the 2 nd external gear 22 internally mesh with the internal gear 16. The number of teeth of the 1 st external gear 21 and the 2 nd external gear 22 is one less than that of the internal gear 16.

Therefore, every 1 rotation of the crankshaft 38, the 1 st external gear 21 and the 2 nd external gear 22 oscillate 1 time, and their phases are shifted from the internal gear 16 by an amount corresponding to the difference in the number of teeth (corresponding to 1 tooth), thereby rotating. This rotation is transmitted to the inner rollers 34 and the inner pins 33 that penetrate the 1 st external gear 21 and the 2 nd external gear 22, and the inner pins 33 revolve around the axial center C16 of the internal gear 16. The 1 st carrier 31 and the 2 nd carrier 32 supporting the inner pin 33 rotate around the axial center C16 of the internal gear 16 by the revolution of the inner pin 33.

As a result, the rear arm (the 2 nd target member) of the manipulator connected to the 2 nd wheel carrier 32 is rotated at a decelerated speed with respect to the front arm (the 1 st target member) of the manipulator connected to the flange portion 14B of the housing 14.

Here, in the gear device 12, a recess 36 is provided between the inner pin (post member) 33 and the inner pin 33 on the surface 31E of the 1 st carrier 31 facing the 1 st external gear 21. The recess 36 overlaps the 1 st main bearing 41 by δ (36-41C) when viewed in the radial direction. However, the 1 st contact angle θ 1 of the 1 st main bearing 41 of the present embodiment is not 0 degrees, and the recess 36 is not overlapped with the 1 st action line F1 of the 1 st main bearing 41 by a distance L (36 to F1). That is, no material-free space exists on the 1 st acting line F1 of the resultant force of the force transmitted to the 1 st rolling element 41A in the 1 st carrier 31. Therefore, the 1 st carrier 31 has less strength reduction due to the formation of the concave portion 36.

On the other hand, in the gear device 12, a plurality of concave portions 36 (having a size that can overlap the 1 st main bearing 41 in the radial direction) are formed on a surface 31E of the 1 st carrier 31 facing the 1 st external gear wheel 21. Therefore, the weight of the 1 st carrier 31 can be greatly reduced by the total volume of the plurality of large recesses 36, and accordingly, the weight of the entire apparatus can be greatly reduced.

In addition, although the gear device 12 has a problem that the volume of the internal space of the device is small and the sealing space of the lubricant is small, the space of the concave portion 36 and the auxiliary concave portion 37 can be used as an additional sealing space of the lubricant for the problem. This can further alleviate the temperature rise and pressure rise of the lubricant in the gear device 12, can further improve the durability of the oil seal, and can further suppress the deterioration of the lubricant.

Here, in the present gear device 12, an auxiliary recess 37 is provided continuously with the recess 36 at an end portion of the recess 36 on the opposite side to the 1 st external gear. The structure and operation of the concave portion 36 and the auxiliary concave portion 37 of the gear device 12 are summarized as follows.

First, in the present gear device 12, the 1 st line of action F1 of the 1 st main bearing 41 does not overlap not only the recess 36 but also the auxiliary recess 37 by the distance L (36-F1) (does not overlap both the recess 36 and the auxiliary recess 37). Therefore, the influence of the strength drop due to the additional formation of the auxiliary recess 37 so as to be continuous with the recess 36 can be further reduced.

Next, the 1 st main bearing 41 has a 1 st contact angle θ 1 of not 0 degrees, and the load transmitted to the 1 st rolling element 41A basically acts on the 1 st line of action F1, but may act in the radial direction. However, in the present gear device 12, the recess 36 is not overlapped with the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41 by a distance L (36-C41A) when viewed in the radial direction. Therefore, even if a load is generated in the radial direction, it is possible to cope with the load with high strength.

On the other hand, the auxiliary concave portion 37 has a larger reduction ratio of the cross-sectional area with distance from the 1 st external gear wheel 21 than the concave portion 36, and its influence on the decrease in strength is originally smaller than the concave portion 36. In consideration of this point, in the present gear device 12, the auxiliary concave portion 37 is provided so as to overlap the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41 when viewed in the radial direction. That is, the auxiliary concave portion 37 is extended to a position deeper by δ (37-C41A) than the center C41A of the 1 st rolling element 41A. As a result, the volumes of the recess 36 and the auxiliary recess 37 can be ensured to be larger, and a larger weight reduction effect can be obtained.

In this way, in the present gear device 12, the formation position and size of the concave portion 36 or the auxiliary concave portion 37 formed in the 1 st carrier 31 are determined by the relationship with the position of the 1 st main bearing 41 and the 1 st line of action F1. In other words, only by determining these configurations by the combination of the two elements described above, the weight of the 1 st wheel frame 31 can be reduced effectively and reasonably while suppressing the decrease in strength of the 1 st wheel frame 31.

The concave portion 36 or the auxiliary concave portion 37 in the present invention is defined as a "concave portion", that is, a "bottomed space" having a "bottom" in the wheel frame. That is, the concept of the concave portion 36 or the auxiliary concave portion 37 does not include a through hole penetrating the wheel frame. Further, the present invention does not include a recess or an auxiliary recess which satisfies the above-described configuration by forming a recess or a through-hole which does not satisfy the above-described conditions in the wheel frame and then blocking a part of the recess or the through-hole with another member. In other words, the bottom of the recess is constituted by the material of the wheel carrier.

More specifically, for example, a space in which a part of a through-hole is closed by a member other than the wheel frame, such as a bolt, a knock pin, or a plug of a grease supply/discharge port, after the through-hole is formed in the wheel frame, and the above-described condition is finally satisfied is not included in the recess or the auxiliary recess of the present invention. This is because, when the recessed portion or the through hole is formed in a state not satisfying the above-described conditions, the strength of the wheel frame expected in the present invention cannot necessarily be maintained even if the wheel frame is subsequently closed by another member.

For example, the gear device 12 has a 2 nd recessed portion 36Sp between the inner pin 33 and the inner pin 33, and further has a through-hole 31P communicating with the 2 nd recessed portion 36Sp, having a smaller cross-sectional area than the 2 nd recessed portion 36Sp, and penetrating the 1 st carrier 31. In the structure of "forming the through-hole 31P by the 2 nd concave portion 36 Sp", since the portion having a larger cross-sectional area (the 2 nd concave portion 36Sp) exists inside the device, for example, when this structure is used for a grease discharge port, an advantage that the flow at the time of grease discharge is smoother can be obtained. Further, the structure is reasonable because the weight reduction effect of the 2 nd recessed portion 36Sp formed at the same position (having a large cross-sectional area and a small strength drop) in the same shape as the recessed portion 36 and the effect of suppressing the strength drop due to the smaller cross-sectional area of the through-hole 31P are both achieved.

However, even if the through-hole 31P having such a structure is partially plugged after the grease supply and finally has a spatial structure according to the condition of the concave portion of the present invention, it is impossible to avoid a decrease in strength of the wheel frame material due to the formation of the through-hole 31P. Therefore, in the present invention, the 2 nd recessed portion 36Sp that is closed by a member different from the wheel frame and eventually becomes the configuration of the recessed portion 36 of the present invention is excluded from the concept of the recessed portion of the present invention (even if the position and shape of the 2 nd recessed portion 36Sp itself are the same as those of the other recessed portions 36).

In other words, in the gear device 12, the recessed portions 36 according to the present invention have only seven recessed portions other than the 2 nd recessed portion 36 Sp. As described above, in the present invention, it is not excluded that the wheel frame is formed with the recessed portions or the through holes other than the recessed portions according to the present invention.

Fig. 4 and 5 show examples of other embodiments of the present invention.

In the gear device 90, the recess 81 overlaps δ (81-41C) with the 1 st outer ring 41C of the 1 st main bearing 41 when viewed in the radial direction, but the recess 81 does not overlap with the 1 st action line F1 of the 1 st main bearing 41 by a distance L (81-F1). Therefore, the basic operational effect of "suppressing the decrease in strength" obtained according to the present invention can be sufficiently achieved.

However, in the present gear device 90, the concave portion 81 is formed by forging or casting, and has a bottom surface 81B perpendicular to the axis. That is, the auxiliary recess is not connected to the recess 81.

Further, since the bottom surface 81B of the concave portion 81 enters δ (81-C41A) into the 1 st carrier 31 from the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41, the concave portion 81 overlaps with the center C41A of the 1 st rolling element 41A of the 1 st main bearing 41 as viewed in the radial direction. That is, the recess 81 is formed larger than in the previous embodiment, and weight reduction can be achieved.

In the gear device 90, the spot facing space 31K for accommodating the head 80A of the inner pin bolt 80 for connecting the inner pin 33 to the 1 st carrier 31 is formed of an annular space that continuously winds one turn in the circumferential direction. Therefore, the spot-facing space 31K can be made lighter as compared with the case where the circular spot-facing space 31B is formed for each inner pin bolt 80 as in the conventional gear device 12.

Since other structures are the same as those of the conventional gear device 12, the same or similar portions are denoted by the same reference numerals as those of the gear device 12 in the drawings, and redundant description thereof is omitted.

In the above embodiment, an angular ball bearing having a contact angle of 40 degrees is used as the main bearing (the 1 st main bearing 41). However, the contact angle of the main bearing according to the present invention does not necessarily have to be 40 degrees. For example, the contact angle may be about 20 degrees, or may be 0 degrees (that is, the bearing may be a bearing in which the line of action is on a radial plane). However, if the contact angle of the main bearing is set to a small value of 0 degrees or close to 0 degrees, the formable concave portion tends to be small, and therefore the contact angle of the main bearing is preferably not 0 degrees, and more preferably 15 degrees or more.

Further, although the 1 st main bearing 41 and the 2 nd main bearing 42 in which the rolling elements are constituted by "balls" are used in the gear device 12 or 90, the present invention can be similarly applied to an angular contact roller bearing, a tapered roller bearing in which the rolling elements are constituted by "rollers", or a roller bearing in which a contact angle is 0 degree.

In the gear device 12, 90, the

concave portion

36, 81 is provided on the surface 31E of the 1 st carrier 31 facing the 1 st external gear 21. However, the concave portion according to the present invention may be provided on a surface 32E of the 2 nd carrier 32 facing the 2 nd external gear 22 to which the inner pin (column member) 33 is integrally connected, for example. Of course, the concave portion according to the present invention may be provided on both the surface 31E of the 1 st carrier 31 facing the 1 st external gear 21 and the surface 32E of the 2 nd carrier 32 facing the 2 nd external gear 22.

In the gear device 12, 90, the present invention is applied to a so-called central crank type eccentric oscillation gear device 12, 90 in which the crankshaft 38 that oscillates the 1 st external gear 21 and the 2 nd external gear 22 is positioned on the axial center C16 of the internal gear 16. However, as an eccentric oscillating type gear device, there is also known a so-called split type gear device in which a plurality of crankshafts 38 are provided at positions offset from the axial center C16 of the internal gear 16.

When using a distribution gear, the following structure is generally adopted: a pair of wheel carriers are disposed on axial side portions of the external gear, and the wheel carriers are connected together by wheel carrier pins corresponding to the column members. Also, the crankshaft itself may be considered as a pillar member. Therefore, when the gear device having such a structure is used, the concave portion that overlaps the main bearing when viewed in the radial direction but does not overlap the line of action of the main bearing can be formed between the carrier pin and the carrier pin, between the crankshaft and the crankshaft, or between the carrier pin and the crankshaft on the surface of the carrier that faces the external gear. That is, the present invention can be applied to such a distributed eccentric oscillating type gear device as well, and the same operational effects can be obtained.

Further, the above-described gear device shows the external-tooth oscillating type eccentric oscillating gear device 12, 90 in which the 1 st external gear 21 and the 2 nd external gear 22 oscillate with respect to the internal gear 16 by the crankshaft 38. However, as an eccentric oscillating type gear device, an internal-tooth oscillating type gear device in which an internal gear oscillates with respect to an external gear via a crankshaft is also known. The present invention can be similarly applied to such an eccentric oscillating type gear device of a type that oscillates the internal gear, and can obtain the same operational effects.

The present invention is not limited to the eccentric oscillating type gear device, and can be applied to a gear device having a simple planetary gear mechanism, for example. In the case of using a gear device having a simple planetary gear mechanism, a concave portion that overlaps the main bearing when viewed in the radial direction but does not overlap the line of action of the main bearing may be formed between the planetary pins (column members) that support the planetary gears and the planetary pins, which are disposed on the surface of the carrier on the side portion in the axial direction of the planetary gears (external gears) that faces the planetary gears. This also achieves the same operational effect.

In addition, the carrier according to the present invention does not necessarily have to be provided in a pair on both sides in the axial direction of the external gear. For example, the column member may be provided only on one side portion in the axial direction of the external gear, and may protrude from the carrier in a cantilever state so as to penetrate the external gear. In such a gear device, the same operational effect can be obtained by forming the concave portions that overlap the main bearing but do not overlap the line of action of the main bearing when viewed in the radial direction between the column members and the column members on the surface of the carrier facing the external gear.

The gear device according to the present invention is not limited to the use of the gear device as a speed reducer or as a speed increasing device.

Claims

1. A gear device is provided with: a housing; an inner gear provided to the housing; an outer gear engaged with the inner gear; a carrier disposed on an axial side portion of the external gear; a main bearing disposed between the housing and the wheel carrier; and a plurality of column members connected to the carrier and penetrating the external gear, the gear device being characterized in that,

a recessed portion is provided between the column member and the column member on a surface of the wheel carrier facing the external gear,

the recess overlaps the main bearing as viewed radially,

without the recess overlapping the line of action of the main bearing.

2. The gear arrangement according to claim 1,

the gear device further has an auxiliary recess portion that is provided continuously from an end portion of the recess portion on the opposite side from the external gear, and that has a larger proportion of a cross-sectional area that decreases with distance from the external gear than the recess portion,

the line of action of the main bearing does not overlap with both the recess and the auxiliary recess.

3. Gear unit according to claim 1 or 2,

the center of the rolling element of the main bearing does not overlap the recess when viewed in the radial direction.

4. The gear arrangement according to claim 1,

the center of the rolling element of the main bearing overlaps with the auxiliary recess when viewed in the radial direction.

5. The gear arrangement according to claim 2,

6. A gear device is provided with: a housing; an inner gear provided to the housing; an outer gear engaged with the inner gear; a carrier disposed on an axial side portion of the external gear; a main bearing disposed between the housing and the wheel carrier; and a plurality of column members connected to the carrier and penetrating the external gear, the gear device being characterized in that,

the recess overlaps the main bearing as viewed radially,

while the recess does not overlap the line of action of the main bearing,

the gear device further has a 2 nd recessed portion between the column member and the column member, and a through hole communicating with the 2 nd recessed portion, having a smaller cross-sectional area than the 2 nd recessed portion, and penetrating the wheel carrier.