CN112145557A - Bearing and speed reducer - Google Patents

Bearing and speed reducer Download PDF

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Publication number
CN112145557A
CN112145557A CN202010456071.8A CN202010456071A CN112145557A CN 112145557 A CN112145557 A CN 112145557A CN 202010456071 A CN202010456071 A CN 202010456071A CN 112145557 A CN112145557 A CN 112145557A
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CN
China
Prior art keywords
bearing
axial direction
inner ring
ring
main bearing
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Pending
Application number
CN202010456071.8A
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Chinese (zh)
Inventor
古田和哉
栩川佑树
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Nabtesco Corp
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Nabtesco Corp
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Publication of CN112145557A publication Critical patent/CN112145557A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/08—General details of gearing of gearings with members having orbital motion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/581—Raceways; Race rings integral with other parts, e.g. with housings or machine elements such as shafts or gear wheels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/28—Toothed gearings for conveying rotary motion with gears having orbital motion
    • F16H1/32—Toothed gearings for conveying rotary motion with gears having orbital motion in which the central axis of the gearing lies inside the periphery of an orbital gear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/02—Gearboxes; Mounting gearing therein
    • F16H57/021—Shaft support structures, e.g. partition walls, bearing eyes, casing walls or covers with bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • F16C19/364—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/38—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers
    • F16C19/383—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F16C19/385—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings
    • F16C19/386—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings in O-arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
    • F16C2240/30—Angles, e.g. inclinations
    • F16C2240/34—Contact angles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2322/00—Apparatus used in shaping articles
    • F16C2322/39—General buildup of machine tools, e.g. spindles, slides, actuators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2322/00—Apparatus used in shaping articles
    • F16C2322/50—Hand tools, workshop equipment or manipulators
    • F16C2322/59—Manipulators, e.g. robot arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2361/00—Apparatus or articles in engineering in general
    • F16C2361/61—Toothed gear systems, e.g. support of pinion shafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2361/00—Apparatus or articles in engineering in general
    • F16C2361/65—Gear shifting, change speed gear, gear box
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/28—Toothed gearings for conveying rotary motion with gears having orbital motion
    • F16H1/32—Toothed gearings for conveying rotary motion with gears having orbital motion in which the central axis of the gearing lies inside the periphery of an orbital gear
    • F16H2001/323—Toothed gearings for conveying rotary motion with gears having orbital motion in which the central axis of the gearing lies inside the periphery of an orbital gear comprising eccentric crankshafts driving or driven by a gearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/02—Gearboxes; Mounting gearing therein
    • F16H2057/02086—Measures for reducing size of gearbox, e.g. for creating a more compact transmission casing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/08—General details of gearing of gearings with members having orbital motion
    • F16H2057/085—Bearings for orbital gears

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Rolling Contact Bearings (AREA)
  • Retarders (AREA)

Abstract

The invention provides a bearing and a speed reducer. The bearing includes: an outer ring; an inner ring having an inner peripheral surface and an axial end surface; and a rolling element disposed between the outer ring and the inner ring, and having a load line of action that does not pass through the inner circumferential surface.

Description

Bearing and speed reducer
Technical Field
The invention relates to a bearing and a speed reducer.
Background
A reduction gear is used for an industrial robot, a machine tool, or the like to reduce the rotation of a rotation drive source such as a motor (see, for example, patent document 1). The reduction gear disclosed in patent document 1 includes: an external gear; an internal gear which is in internal contact engagement with the external gear; a housing provided with an internal gear; a carrier that rotates relative to the housing; a main bearing disposed between the housing and the carrier; and an eccentric body shaft rotatably supported by the carrier via a tapered roller bearing. In this reduction gear, the external gear is attached to the eccentric body of the eccentric body shaft via a needle bearing.
Further, since the main bearing uses the tapered roller bearing, the allowable torque, the rigidity of the speed reducer, and the like can be improved as compared with a structure in which the main bearing uses an angular ball bearing. On the contrary, since the load applied to the speed reducer is increased, the amount of deformation of the components of the speed reducer may be increased, and the components of the speed reducer need to be formed to have an appropriate thickness. In particular, since a load of the main bearing is easily applied to a portion of the main bearing where the inner ring is attached, it is necessary to form the main bearing to have a thickness capable of suppressing deformation.
Patent document 1: japanese patent laid-open publication No. 2016-
Disclosure of Invention
Problems to be solved by the invention
However, when the thickness of the constituent member of the speed reducer needs to be made large, there are problems such as an increase in design restrictions and an increase in the size of the speed reducer. Therefore, there is room for improvement in the conventional bearing in order to suppress an increase in thickness of a member constituting a rotating device such as a reduction gear to which the bearing is attached.
Accordingly, the present invention provides a bearing capable of reducing the thickness of a component of a rotating machine, and a reduction gear provided with the bearing.
Means for solving the problems
The bearing related to one technical scheme of the invention comprises: an outer ring; an inner ring having an inner peripheral surface and an axial end surface; and a rolling element disposed between the outer ring and the inner ring, and having a load line of action that does not pass through the inner circumferential surface.
According to the bearing of one aspect of the present invention, it is possible to avoid the load acting line from passing through the wall portion of the member having the outer peripheral surface that holds the inner peripheral surface of the inner ring of the bearing so as to cross in the radial direction.
Here, the "wall portion" refers to a portion that does not include a space such as the "hole" or the "recess".
This can suppress deformation of the wall portion of the member supporting the inner ring so as to be deflected inward in the radial direction, and can reduce the load applied to the member supporting the inner ring. Thus, the thickness of the constituent members of the apparatus to which the bearing is mounted can be reduced.
The bearing according to an aspect of the present invention includes: an outer ring having a predetermined axis as a center; an inner ring having an end surface in the direction of the axis; and a rolling element disposed between the outer ring and the inner ring, and having a load line passing through the end surface.
According to the bearing of one aspect of the present invention, it is possible to avoid the load acting line from passing through the wall portion of the member having the outer peripheral surface that holds the inner peripheral surface of the inner ring of the bearing so as to cross in the radial direction.
This can suppress deformation of the wall portion of the member supporting the inner ring so as to be deflected inward in the radial direction, and can reduce the load applied to the member supporting the inner ring. Thus, the thickness of the constituent members of the apparatus to which the bearing is mounted can be reduced.
A reduction gear according to an aspect of the present invention includes: an outer member having an outer race; an inner member having an inner ring and a bore for supporting the shaft member to be rotatable; and a bearing disposed between the outer ring and the inner ring and having a load acting line that does not pass through an inner circumferential surface of the hole of the shaft hole.
According to the speed reducer of one aspect of the present invention, the load acting line can be prevented from passing through the inner circumferential surface of the hole. Thus, the portion formed with a small thickness between the outer peripheral surface of the inner member and the inner peripheral surface of the hole of the shaft hole can be suppressed from being deformed so as to be deflected inward in the radial direction, and the load applied to the portion of the inner member to which the inner ring is attached can be reduced. Therefore, the thickness of the portion of the inner member to which the inner ring is attached can be reduced, and the reduction gear can be downsized.
In the reduction gear according to the above aspect, the contact angle of the bearing may be 40 ° or more and 50 ° or less.
For the speed reducer of the above technical solution, a distance in the axial direction from an axial end surface of the inner ring to an intersection point where a surface of the inner ring intersects with the load acting line may be a, and a dimension of the entire inner ring and the outer ring in the axial direction may be B, and a relationship of 0 or more and a/B or less and 0.2 or less may be satisfied.
In the reduction gear according to the above aspect, a distance in the axial direction from the axial end surface of the inner race to an intersection point where the surface of the inner race intersects the load acting line may be a, a dimension of the inner race in the axial direction may be B1, and a relationship of 0/B1 to 0.3 may be satisfied.
A reduction gear according to an aspect of the present invention includes: a bearing, the bearing comprising: an outer ring formed in an annular shape and having an outer rolling surface facing radially inward; an inner ring disposed coaxially with the outer ring and having an inner rolling surface facing the radially outer side; and a plurality of rollers rolling on the inner rolling surface and the outer rolling surface; an outer member to which the outer ring is attached; an inner member having a bearing mounting portion to which the inner ring is mounted and the bearing mounting portion having a shaft hole; a shaft member disposed in the shaft hole and rotatably supported by the inner member; and a needle bearing interposed between the bearing mounting portion and the shaft member, the needle bearing having a plurality of rolling elements rolling on an inner peripheral surface of the shaft hole, a load acting line of the bearing passing through a position of the bearing mounting portion on an outer side in an axial direction of the bearing than the inner peripheral surface of the shaft hole, a contact angle of the bearing being 40 ° or more and 50 ° or less, a distance in the axial direction from an end portion on the outer side in the axial direction of the inner ring to an intersection point of a surface of the inner ring and the load acting line being a, a dimension of the entire inner ring and the outer ring in the axial direction being B, and a dimension of the inner ring in the axial direction being B1, wherein a relationship of 0. ltoreq. a/b.ltoreq.0.2 and a relationship of 0. ltoreq. a/B1. ltoreq.0.3 are satisfied.
According to the reduction gear of one aspect of the present invention, the thickness of the bearing mounting portion can be reduced, and the reduction gear can be miniaturized.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the aspect of the present invention, it is possible to provide a bearing capable of reducing the thickness of a component of a rotating machine, and a reduction gear including the bearing.
Drawings
Fig. 1 is a half sectional view of a speed reducer according to an embodiment.
Fig. 2 is a partially enlarged view of a cross section of the reduction gear shown in fig. 1.
Fig. 3 is a partially enlarged view of a cross section of the reduction gear shown in fig. 2.
Fig. 4 is a partially enlarged view of a cross section of the reduction gear shown in fig. 1.
Fig. 5 is a graph showing a relationship between a contact angle, a lifetime, and rigidity of the 1 st main bearing of the reduction gear according to the embodiment.
Description of the reference numerals
1. A speed reducer; 2. an outer cylinder (outer member); 3. a carrier (inner member); 4. a crankshaft (shaft member); 6A, the 1 st main bearing (bearing); 6B, the 2 nd main bearing (bearing); 7A, 1 st crankshaft bearing (needle bearing); 7B, 2 nd crankshaft bearing (needle bearing); 32. a main bearing mounting portion (bearing mounting portion); 41. 1 st axle mounting hole (axle hole); 51. a main bearing mounting portion (bearing mounting portion); 54. a 2 nd shaft mounting hole (shaft hole); 61A, 61B, an outer ring; 61c, an outer rolling surface; 62A, 62B, inner ring; 62a, an inner peripheral surface; 62b, end faces (axial end faces); 62d, inner rolling surface; 63A, 63B, rollers (rolling elements); 81. rollers (rolling bodies); AL1, AL2, load line of action; o, axis.
Detailed Description
Hereinafter, a reduction gear 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the structures having the same or similar functions. In addition, a repetitive description of these structures may be omitted. The speed reducer 1 of the present embodiment is an eccentric oscillating type gear transmission device applied to, for example, a joint portion of a robot arm.
Fig. 1 is a half sectional view of a speed reducer according to an embodiment.
As shown in fig. 1, the speed reducer 1 includes: an outer cylinder 2 (outer member) as a housing; a carrier 3 (inner member) rotatably supported by the outer tube 2; a plurality of crankshafts 4 (shaft members) rotatably supported by the carrier 3; a 1 st oscillating gear 5A and a 2 nd oscillating gear 5B rotatably attached to the plurality of crankshafts 4; a 1 st main bearing 6A and a 2 nd main bearing 6B interposed between the outer tube 2 and the carrier 3; a 1 st crank bearing 7A and a 2 nd crank bearing 7B interposed between the carrier 3 and the crankshaft 4; a 1 st eccentric bearing 8A interposed between the crankshaft 4 and the 1 st oscillating gear 5A; and a 2 nd eccentric bearing 8B interposed between the crankshaft 4 and the 2 nd oscillating gear 5B. The speed reducer 1 is an eccentric oscillating type gear transmission device that rotates an input shaft, not shown, relative to an outer cylinder 2 by relatively rotating the outer cylinder 2 and a carrier 3 about an axis O to obtain output rotation reduced in speed by the input rotation of the input shaft. In the following description, a direction along the axis O is referred to as an axial direction (axial direction), a direction perpendicular to the axis O and extending radially from the axis O is referred to as a radial direction, and a direction revolving around the axis O is referred to as a circumferential direction. In the following description, the term "axially inside" used means the center side of the outer tube 2, and the term "axially outside" means the side opposite to the center of the outer tube 2.
The outer cylinder 2 is formed in a cylindrical shape centered on the axis O. The inner circumferential surface of the outer cylinder 2 includes: an internal tooth portion 21 in which a plurality of pin grooves 21A are formed, a 1 st outer ring holding portion 22 that holds an outer ring 61A of the 1 st main bearing 6A, a 2 nd outer ring holding portion 23 that holds an outer ring 61B of the 2 nd main bearing 6B, and a seal portion 24 to which the oil seal 11 is attached.
The internal teeth 21 are formed in an axially intermediate portion of the inner peripheral surface of the outer cylinder 2. The term "intermediate" used in the present embodiment means not only the intermediate between both ends of an object but also a range inside between both ends of an object. The plurality of pin grooves 21a extend in the axial direction, respectively. The plurality of pin grooves 21a are arranged at equal intervals in the circumferential direction. In each pin groove 21a, a cylindrical internal gear pin 25 is rotatably held.
The 1 st outer ring holding portion 22 and the 2 nd outer ring holding portion 23 are located on opposite sides of the internal tooth portion 21. The 1 st outer ring holding portion 22 and the 2 nd outer ring holding portion 23 are respectively adjacent to the inner tooth portions 21 in the axial direction. The 1 st outer ring holding portion 22 is located on the 1 st side in the axial direction with respect to the internal tooth portions 21. The 1 st outer ring holding portion 22 extends in the axial direction with a constant inner diameter about the axis O. The 1 st outer ring holding portion 22 is connected to the internal tooth portion 21 via a step surface 26. The step surface 26 faces outward in the axial direction and extends in the circumferential direction and the radial direction. The 2 nd outer ring holding portion 23 is located on the 2 nd side in the axial direction with respect to the internal tooth portions 21. The 2 nd outer ring holding portion 23 extends in the axial direction with a constant inner diameter about the axis O. The 2 nd outer ring holding portion 23 is connected to the internal tooth portion 21 via a stepped surface 27. The step surface 27 faces the outside in the axial direction and extends in the circumferential direction and the radial direction.
The seal portion 24 is located on the opposite side of the internal gear portion 21 with the 1 st outer ring holding portion 22 interposed therebetween. The seal portion 24 is adjacent to the 1 st outer ring holding portion 22 in the axial direction. The seal portion 24 extends with a certain inner diameter with the axis O as the center. The inner diameter of the seal portion 24 is larger than that of the 1 st outer ring holding portion 22. The seal portion 24 is connected to the 1 st outer ring holding portion 22 via a step surface 28. The step surface 28 faces the outside in the axial direction and extends in the circumferential direction and the radial direction. The outer peripheral portion of the oil seal 11 contacts the seal portion 24.
The carrier 3 functions as an output shaft to which a driven part that receives the output rotation of the reduction gear 1 is attached. The carrier 3 is formed in a cylindrical shape with the axis O as the center. The carrier 3 is disposed on the inner circumferential side of the outer cylinder 2. The carrier 3 protrudes to both sides in the axial direction from the outer cylinder 2. The carrier 3 is formed so as to be axially dividable into the 1 st carrier assembly 30 and the 2 nd carrier assembly 50. The 1 st carrier assembly 30 is disposed on the 1 st side in the axial direction with respect to the 2 nd carrier assembly 50. A surface of the 1 st carrier assembly 30 facing the opposite side (the 1 st side in the axial direction) from the 2 nd carrier assembly 50 is a mounting surface 30a to which the driven portion is mounted. The 1 st carrier assembly 30 and the 2 nd carrier assembly 50 are fastened to each other and integrated.
The 1 st gear rack assembly 30 includes a base portion 31 and a plurality of strut portions, not shown. The base 31 is disposed on the same side as the 1 st outer ring holding portion 22 in the axial direction with respect to the internal teeth portion 21 of the outer cylinder 2. The base 31 is formed in a disk shape centered on the axis O. The base 31 is rotatably supported by the outer cylinder 2 via the 1 st main bearing 6A. The base portion 31 has a 1 st main bearing mounting portion 32 to which the 1 st main bearing 6A is mounted. The 1 st main bearing mounting portion 32 is formed at an end portion of the base portion 31 on the 2 nd carrier assembly 50 side in the axial direction.
The outer peripheral surface of the base 31 includes a 1 st inner ring holding portion 33 that holds the inner ring 62A of the 1 st main bearing 6A and a seal portion 34 to which the oil seal 11 is attached. The 1 st inner ring holding portion 33 is an outer peripheral surface of the 1 st main bearing mounting portion 32. At least a part of the 1 st inner ring holding portion 33 is opposed to the 1 st outer ring holding portion 22 of the outer cylinder 2 in the radial direction. The 1 st inner race holding portion 33 extends in the axial direction with a constant outer diameter with the axis O as the center. The 1 st inner ring holding portion 33 includes an axially inner end portion of the outer peripheral surface of the base portion 31. At least a part of the seal portion 34 is opposed to the seal portion 24 of the outer cylinder 2 in the radial direction. The seal portion 34 is adjacent to the 1 st inner ring holding portion 33 in the axial direction. The seal portion 34 is disposed axially outward of the 1 st inner ring holding portion 33. The seal portion 34 extends with a certain outer diameter with the axis O as the center. The seal portion 34 is connected to the 1 st inner ring holding portion 33 via a stepped surface 35. The step surface 35 faces the axially inner side and extends in the circumferential direction and the radial direction. The inner peripheral portion of the oil seal 11 is in contact with the seal portion 34.
The base 31 has a 1 st shaft mounting hole 41 (shaft hole) into which the crankshaft 4 is inserted. The 1 st shaft mounting holes 41 are provided in the same number as the plurality of crankshafts 4. The 1 st shaft mounting holes 41 are arranged at equal intervals in the circumferential direction. The inner peripheral surface of the 1 st shaft mounting hole 41 is formed in a circular shape as viewed in the axial direction. The 1 st shaft mounting hole 41 is open on the inner side in the axial direction. At least a part of the 1 st shaft mounting hole 41 is provided in the 1 st main bearing mounting portion 32. The inner circumferential surface of the 1 st shaft attachment hole 41 includes: the 1 st shaft support portion 42, the bush holding portion 43, the diameter-enlarged portion 44, and the communication portion 45. The 1 st shaft support portion 42 and the enlarged diameter portion 44 are located at the 1 st main bearing mounting portion 32. The bush holding portion 43 and the communication portion 45 are located axially outward of the 1 st main bearing mounting portion 32.
The 1 st shaft support portion 42 is formed at an axially inner end portion of the 1 st shaft mounting hole 41. The 1 st shaft support portion 42 extends in the axial direction with a certain inner diameter. The bush holding portion 43 is formed on the outer side in the axial direction with respect to the 1 st shaft support portion 42. The bush holding portion 43 is formed coaxially with the 1 st shaft support portion 42. The bush holding portion 43 extends in the axial direction with a certain inner diameter. The inner diameter of the bush holding portion 43 is smaller than the inner diameter of the 1 st shaft support portion 42. The enlarged diameter portion 44 is formed between the 1 st shaft support portion 42 and the bush holding portion 43. The enlarged diameter portion 44 is connected to the 1 st shaft support portion 42 and the bush holding portion 43. The enlarged diameter portion 44 is formed over the entire circumference so as to have an enlarged inner diameter larger than the inner diameter of the 1 st shaft support portion 42 and the inner diameter of the bush holding portion 43. The communication portion 45 is adjacent to the bush holding portion 43 in the axial direction. The communication portion 45 is formed on the opposite side of the 1 st shaft support portion 42 with the bush holding portion 43 interposed therebetween. The communication portion 45 is open on the outside in the axial direction. The inner diameter of the communication portion 45 is smaller than the inner diameter of the bush holding portion 43. A sealing cap 12 is fitted inside the communication portion 45. A stepped surface 46 is formed between the bush holding portion 43 and the communication portion 45. The step surface 46 extends in a direction orthogonal to the axial direction. The step surface 46 faces the axially inner side.
Although not shown, a plurality of column portions are provided one by one between the pair of 1 st shaft attachment holes 41 in the circumferential direction. The plurality of pillar portions project in the axial direction from the base portion 31. The plurality of strut portions are located inside the internal tooth portion 21 of the outer cylinder 2. The plurality of pillar portions are provided integrally with the base portion 31.
The 2 nd carrier assembly 50 is disposed on the opposite side of the base 31 of the 1 st carrier assembly 30 in the axial direction with the internal teeth 21 of the outer cylinder 2 interposed therebetween. That is, the 2 nd carrier assembly 50 is disposed on the 2 nd side in the axial direction with a space from the base portion 31. The 2 nd carrier assembly 50 is fastened to the protruding end portions of the plurality of column portions of the 1 st carrier assembly 30, and is integrated with the 1 st carrier assembly 30. The 2 nd carrier assembly 50 is formed in a disk shape centered on the axis O. The 2 nd carrier assembly 50 is rotatably supported by the outer cylinder 2 via the 2 nd main bearing 6B. The 2 nd carrier assembly 50 has a 2 nd main bearing mounting portion 51 to which the 2 nd main bearing 6B is mounted. The 2 nd main bearing mounting portion 51 is formed at an axially inner end portion of the 2 nd carrier assembly 50.
The 2 nd carrier assembly 50 includes a 2 nd inner ring holding portion 52 for holding the inner ring 62B of the 2 nd main bearing 6B on the outer peripheral surface thereof. The 2 nd inner ring holding portion 52 is an outer peripheral surface of the 2 nd main bearing mounting portion 51. At least a part of the 2 nd inner ring holding portion 52 is opposed to the 2 nd outer ring holding portion 23 of the outer cylinder 2 in the radial direction. The 2 nd inner race holding portion 52 extends in the axial direction with a certain outer diameter with the axis O as the center. The 2 nd inner race holding portion 52 includes an axially inner end portion of the outer peripheral surface of the 2 nd carrier assembly 50. A step surface 53 extending in the circumferential direction and the radial direction is connected to an axially outer end portion of the 2 nd inner race retaining portion 52.
The 2 nd carrier assembly 50 has a 2 nd shaft mounting hole 54 (shaft hole) into which the crankshaft 4 is inserted. The 2 nd shaft mounting holes 54 are provided in the same number as the plurality of crankshafts 4. Each 2 nd axle mounting hole 54 is formed coaxially with the 1 st axle mounting hole 41 of the 1 st carrier assembly 30. The inner peripheral surface of the 2 nd shaft mounting hole 54 is formed in a circular shape as viewed in the axial direction. The 2 nd shaft mounting hole 54 is opened on the inner side in the axial direction. At least a part of the 2 nd shaft mounting hole 54 is provided in the 2 nd main bearing mounting portion 51. The 2 nd shaft mounting hole 54 has a 2 nd shaft support 55 and a female screw 56 on its inner peripheral surface. The entire 2 nd shaft support portion 55 and a part of the female screw portion 56 are located in the 2 nd main bearing mounting portion 51.
The 2 nd shaft support portion 55 is formed at an axially inner end portion of the 2 nd shaft mounting hole 54. The 2 nd shaft support portion 55 extends in the axial direction with a certain inner diameter. The female screw portion 56 is adjacent to the 2 nd shaft support portion 55 in the axial direction. The female screw portion 56 is formed at an axially outer end of the 2 nd shaft attachment hole 54. The internal thread portion 56 has an inner diameter larger than that of the 2 nd shaft support portion 55. A step surface 57 is formed between the 2 nd shaft support portion 55 and the female screw portion 56. The step surface 57 extends in a direction orthogonal to the axial direction. The step surface 57 faces the outside in the axial direction.
Fig. 2 is a partially enlarged view of a cross section of the reduction gear shown in fig. 1.
As shown in fig. 2, the 1 st main bearing 6A is a tapered roller bearing. The 1 st main bearing 6A is disposed between the outer cylinder 2 and the base portion 31 of the 1 st carrier module 30. The 1 st main bearing 6A includes: an outer race 61A, an inner race 62A, a plurality of rollers 63A, and a cage 64A.
The outer ring 61A is formed in an annular shape centered on the axis O. The outer ring 61A is fitted to the 1 st outer ring holding portion 22 of the outer cylinder 2. The outer race 61A has: an outer peripheral surface 61a extending with a constant outer diameter, an end surface 61b facing the inside in the axial direction, and an outer rolling surface 61c inclined with respect to the axis O. The end surface 61b contacts the step surface 26. The end surface 61b faces an end portion of the internal gear pin 25, and regulates displacement of the internal gear pin 25 to the 1 st side in the axial direction. The outer rolling surface 61c faces radially inward and axially outward.
The inner ring 62A is formed in an annular shape coaxial with the outer ring 61A. The inner ring 62A is fitted to the 1 st inner ring holding portion 33 of the base portion 31 of the 1 st carrier assembly 30. The inner ring 62A has: an inner circumferential surface 62a (bore inner circumferential surface) extending with a constant inner diameter, an end surface 62b (axial end surface) facing outward in the axial direction, a chamfered portion 62c formed between the inner circumferential surface 62a and the end surface 62b, and an inner rolling surface 62d inclined with respect to the axis O. The end surface 62b contacts the step surface 35. The chamfered portion 62c is formed between an axially outer end of the inner peripheral surface 62a and a radially inner end of the end surface 62 b. The inner rolling surface 62d faces the outer rolling surface 61c of the outer race 61A. The inner rolling surface 62d faces radially outward and axially inward.
The plurality of rollers 63A are disposed between the outer ring 61A and the inner ring 62A. The plurality of rollers 63A are arranged at equal intervals in the circumferential direction. The plurality of rollers 63A revolve around the axis O while rolling on the outer rolling surface 61c of the outer ring 61A and the inner rolling surface 62d of the inner ring 62A.
The cage 64A is disposed between the outer race 61A and the inner race 62A. The retainer 64A retains the plurality of rollers 63A. The retainer 64A is formed in an annular shape coaxial with the outer ring 61A. The retainer 64A is formed with a plurality of recesses that individually retain the plurality of rollers 63A.
The contact angle θ of the 1 st main bearing 6A is 40 ° or more and 50 ° or less. The contact angle θ is an inclination angle of a generatrix of the outer rolling surface 61c of the outer ring 61A with respect to the axis O. That is, the contact angle θ is an angle formed by a normal line at an arbitrary point of the outer rolling surface 61c and a straight line orthogonal to the axis O and passing through the arbitrary point.
Here, a (see fig. 3) is a distance in the axial direction from the end surface 62b of the inner ring 62A of the 1 st main bearing 6A to an intersection point P of the surface of the inner ring 62A, which intersects with a load application line AL1 (described later). The dimension of the entire inner ring 62A and the outer ring 61A in the axial direction is B. At this time, the 1 st main bearing 6A is formed so as to satisfy the relationship shown by the following formula (1):
0≤A/B≤0.2···(1)。
further, the dimension of the inner ring 62A in the axial direction is B1. At this time, the 1 st main bearing 6A is formed so as to satisfy the relationship shown by the following equation (2):
0≤A/B1≤0.3···(2)。
fig. 4 is a partially enlarged view of a cross section of the reduction gear shown in fig. 1.
As shown in fig. 4, the 2 nd main bearing 6B is a tapered roller bearing. The 2 nd main bearing 6B is disposed between the outer cylinder 2 and the 2 nd carrier unit 50. The 2 nd main bearing 6B includes: an outer race 61B, an inner race 62B, a plurality of rollers 63B, and a cage 64B.
The outer ring 61B is fitted into the 2 nd outer ring holding portion 23 of the outer cylinder 2. The outer ring 61B has, similarly to the outer ring 61A of the 1 st main bearing 6A: an outer peripheral surface 61a extending with a constant outer diameter, an end surface 61b facing the inside in the axial direction, and an outer rolling surface 61c inclined with respect to the axis O. The end surface 61b contacts the step surface 27. The end surface 61b faces an end portion of the inner pin 25, and restricts displacement of the inner pin 25 to the 2 nd side in the axial direction.
The inner ring 62B is fitted into the 2 nd inner ring holding portion 52 of the 2 nd carrier assembly 50. The inner ring has, similarly to the inner ring 62A of the 1 st main bearing 6A: an inner circumferential surface 62a extending with a constant inner diameter, an end surface 62b facing outward in the axial direction, a chamfered portion 62c formed between the inner circumferential surface 62a and the end surface 62b, and an inner rolling surface 62d inclined with respect to the axis O. The end surface 62b is opposed to the step surface 53. An annular spacer 13 is interposed between the end surface 62b and the step surface 53.
The plurality of rollers 63B are disposed between the outer ring 61B and the inner ring 62B, respectively. The plurality of rollers 63B are arranged at equal intervals in the circumferential direction. The plurality of rollers 63B revolve around the axis O while rolling on the outer rolling surface 61c of the outer ring 61B and the inner rolling surface 62d of the inner ring 62B.
The cage 64B is disposed between the outer race 61B and the inner race 62B. The retainer 64B retains the plurality of rollers 63B. The retainer 64B is formed in an annular shape coaxial with the outer ring 61B. The retainer 64B is formed with a plurality of recesses that individually retain the plurality of rollers 63B.
The contact angle of the 2 nd main bearing 6B is 40 ° or more and 50 ° or less. The contact angle is defined as the 1 st main bearing 6A. Further, the 2 nd main bearing 6B is also formed so as to satisfy the relationship between the above formula (1) and the above formula (2) similarly to the 1 st main bearing 6A.
As shown in fig. 1, the plurality of crankshafts 4 are located on the inner peripheral side of the outer cylinder 2 and arranged at equal intervals in the circumferential direction. Each crankshaft 4 is rotatably supported by the carrier 3 via a pair of 1 st and 2 nd crank bearings 7A and 7B. Specifically, each crankshaft 4 is rotatably supported by the 1 st carrier module 30 via the 1 st crankshaft bearing 7A inside the 1 st shaft mounting hole 41 of the 1 st carrier module 30. Further, each crankshaft 4 is rotatably supported by the 2 nd carrier assembly 50 via a 2 nd crankshaft bearing 7B inside the 2 nd shaft mounting hole 54 of the 2 nd carrier assembly 50. Each crankshaft 4 has a 1 st journal portion 71 and a 2 nd journal portion 72, a 1 st eccentric portion 73 and a 2 nd eccentric portion 74, and a small diameter portion 75.
The 1 st journal portion 71 is disposed inside the 1 st shaft support portion 42 of the 1 st gear frame assembly 30. The 2 nd journal portion 72 is formed coaxially with the 1 st journal portion 71.
The 2 nd journal portion 72 is disposed at a distance from the 1 st journal portion 71 in the axial direction. The 2 nd journal portion 72 is disposed inside the 2 nd shaft support portion 55 of the 2 nd carrier assembly 50.
The 1 st eccentric portion 73 and the 2 nd eccentric portion 74 are disposed between the 1 st journal portion 71 and the 2 nd journal portion 72. The 1 st eccentric portion 73 is disposed on the 1 st journal portion 71 side with respect to the 2 nd eccentric portion 74. The 1 st eccentric portion 73 and the 2 nd eccentric portion 74 are each formed in a cylindrical shape. The 1 st eccentric portion 73 and the 2 nd eccentric portion 74 are eccentric with respect to the common axial center of the 1 st journal portion 71 and the 2 nd journal portion 72. The 1 st eccentric portion 73 and the 2 nd eccentric portion 74 are eccentric by the same eccentric amount with respect to the common axial center of the 1 st journal portion 71 and the 2 nd journal portion 72, respectively. The 1 st eccentric portion 73 and the 2 nd eccentric portion 74 are disposed so as to have a phase difference of a predetermined angle (180 ° in the present embodiment) from each other.
The small diameter portion 75 is disposed on the opposite side of the 1 st journal portion 71 via the 2 nd journal portion 72. The small diameter portion 75 protrudes outward in the axial direction from the 2 nd journal portion 72. The small diameter portion 75 is formed coaxially with the 2 nd journal portion 72. The small diameter portion 75 protrudes outward in the axial direction from the carrier 3. A gear that meshes with the input shaft is attached to the small diameter portion 75, for example.
Each crankshaft 4 is held by the carrier 3 by a restriction member 14. The restricting member 14 includes a 1 st restricting member 15 and a 2 nd restricting member 16. The 1 st regulating member 15 is disposed inside the 1 st shaft mounting hole 41 of the 1 st carrier module 30. The 1 st restriction member 15 is formed in an annular shape coaxial with the 1 st shaft attachment hole 41. The 1 st restricting member 15 is fitted inside the bush holding portion 43 of the 1 st shaft attachment hole 41. The 1 st restricting member 15 is disposed between the stepped surface 46 and the 1 st journal portion 71. The 1 st restricting member 15 contacts the step surface 46 from the inner side in the axial direction, and contacts or approaches the end surface of the 1 st journal portion 71 facing the outer side in the axial direction from the outer side in the axial direction.
The 2 nd limiting member 16 is disposed inside the 2 nd shaft mounting hole 54 of the 2 nd carrier assembly 50. The 2 nd restriction member 16 is formed in an annular shape coaxial with the 2 nd shaft attachment hole 54. The 2 nd restriction member 16 is attached to the female screw portion 56. An external thread 16a that engages with the internal thread portion 56 is formed on the outer peripheral surface of the 2 nd restriction member 16. The 2 nd restriction member 16 surrounds the small diameter portion 75, and is in contact with or close to the end surface of the 2 nd journal portion 72 facing the outside in the axial direction.
The 1 st crank bearing 7A is a needle bearing. The 1 st crank bearing 7A is disposed between the 1 st carrier assembly 30 and the crankshaft 4. The 1 st crank bearing 7A includes a plurality of rollers 81 (rolling elements) and a retainer 82 that retains the plurality of rollers 81.
The plurality of rollers 81 are disposed between the 1 st shaft support portion 42 of the 1 st carrier assembly 30 and the outer peripheral surface of the 1 st journal portion 71 of the crankshaft 4. The plurality of rollers 81 are arranged at equal angular intervals around the 1 st journal portion 71. The plurality of rollers 81 are formed in a cylindrical shape extending in the axial direction. Each roller 81 rolls on the 1 st shaft support part 42 and the outer peripheral surface of the 1 st journal part 71. That is, the 1 st main bearing mounting portion 32 has the 1 st shaft support portion 42 as an inner peripheral surface, and the 1 st main bearing mounting portion 32 functions as an outer ring of the 1 st crank bearing 7A. The 1 st journal portion 71 functions as an inner ring of the 1 st crank bearing 7A.
The retainer 82 extends annularly along the 1 st shaft support portion 42. The retainer 82 is formed with a recess portion for individually retaining the plurality of rollers 81. The retainer 82 protrudes to both sides in the axial direction than the plurality of rollers 81. The axially outer end of the retainer 82 is contactable with the 1 st restricting member 15 from the axially inner side.
The 2 nd crankshaft bearing 7B is a needle bearing. The 2 nd crank bearing 7B is disposed between the 2 nd carrier assembly 50 and the crankshaft 4. The 2 nd crank bearing 7B is formed in the same manner as the 1 st crank bearing 7A. That is, the 2 nd crankshaft bearing 7B includes a plurality of rollers 81 and a retainer 82.
The plurality of rollers 81 are disposed between the 2 nd shaft support portion 55 of the 2 nd carrier assembly 50 and the outer peripheral surface of the 2 nd journal portion 72 of the crankshaft 4. Each roller 81 rolls on the 2 nd shaft support portion 55 and the outer peripheral surface of the 2 nd journal portion 72. That is, the 2 nd main bearing mounting portion 51 has the 2 nd shaft support portion 55 as an inner peripheral surface, and the 2 nd main bearing mounting portion 51 functions as an outer ring of the 2 nd crank bearing 7B. The 2 nd journal portion 72 functions as an inner ring of the 2 nd crank bearing 7B. The axially outer end of the retainer 82 is capable of contacting the 2 nd restricting member 16 from the axially inner side.
The 1 st and 2 nd oscillating gears 5A and 5B are disposed between the base portion 31 of the 1 st carrier assembly 30 and the 2 nd carrier assembly 50. The 1 st swing gear 5A is disposed on the base portion 31 side of the 1 st gear frame assembly 30 with respect to the 2 nd swing gear 5B. The 1 st and 2 nd oscillating gears 5A and 5B are formed in a disk shape having an outer diameter smaller than the inner diameter of the inner teeth 21 of the outer cylinder 2. The 1 st and 2 nd oscillating gears 5A and 5B are capable of oscillating rotation with respect to the carrier 3 and are capable of rotating about the axis O in synchronization with the carrier 3.
The 1 st oscillating gear 5A has external teeth 91 and the same number of shaft insertion holes 92 as the plurality of crankshafts 4. The external teeth 91 are arranged on the outer peripheral surface of the 1 st oscillating gear 5A over the entire circumference, and can mesh with the internal tooth pins 25 of the outer cylinder 2. The plurality of crankshafts 4 penetrate the respective shaft through holes 92 one by one. The 1 st eccentric portion 73 of the crankshaft 4 is disposed inside each shaft insertion hole 92. The shaft through hole 92 is attached to the 1 st eccentric portion 73 via the 1 st eccentric bearing 8A.
The 2 nd swing gear 5B is formed in the same manner as the 1 st swing gear 5A. The 2 nd eccentric portion 74 of the crankshaft 4 is disposed inside each shaft insertion hole 92. The shaft through hole 92 is attached to the 2 nd eccentric portion 74 via the 2 nd eccentric bearing 8B.
When the 1 st eccentric portion 73 eccentrically rotates by the rotation of each crankshaft 4, the 1 st oscillating gear 5A oscillates and rotates about the axis O while meshing with a part of the plurality of internal tooth pins 25 among the internal tooth pins 25 in conjunction with the eccentric rotation of the 1 st eccentric portion 73. When each crankshaft 4 rotates and the 2 nd eccentric portion 74 eccentrically rotates, the 2 nd oscillating gear 5B oscillates and rotates about the axis O while meshing with a part of the plurality of internal tooth pins 25 in conjunction with the eccentric rotation of the 2 nd eccentric portion 74. Therefore, the plurality of crankshafts 4 supported by the 1 st and 2 nd oscillating gears 5A and 5B revolve around the axis O, and the carrier 3 supporting the plurality of crankshafts 4 rotates around the axis O.
Although not shown, the 1 st and 2 nd swing gears 5A and 5B are each formed with the same number of escape holes as the plurality of support portions of the 1 st gear frame assembly 30. The plurality of column parts penetrate the escape holes one by one. Each escape hole is formed with a sufficiently large inner diameter with respect to the column portion so that each column portion does not interfere with the swing rotation of the 1 st swing gear 5A and the swing rotation of the 2 nd swing gear 5B.
The 1 st eccentric bearing 8A is a needle bearing. The 1 st eccentric bearing 8A is disposed between the 1 st oscillating gear 5A and the crankshaft 4. The 1 st eccentric bearing 8A includes a plurality of rollers 101 and a retainer 102 that retains the plurality of rollers 101.
The plurality of rollers 101 are disposed between the inner peripheral surface of the shaft insertion hole 92 of the 1 st swing gear 5A and the outer peripheral surface of the 1 st eccentric portion 73 of the crankshaft 4. The plurality of rollers 101 are arranged at equal angular intervals around the 1 st eccentric portion 73. The plurality of rollers 101 are formed in a cylindrical shape extending in the axial direction. Each roller 101 rolls on the inner peripheral surface of the shaft insertion hole 92 of the 1 st swing gear 5A and the outer peripheral surface of the 1 st eccentric portion 73.
The retainer 102 extends in an annular shape along the inner peripheral surface of the shaft insertion hole 92. The retainer 102 is formed with a recess portion for retaining the plurality of rollers 101 one by one. The retainer 102 protrudes to both sides in the axial direction than the plurality of rollers 102.
The 2 nd eccentric bearing 8B is a needle bearing. The 2 nd eccentric bearing 8B is disposed between the 2 nd oscillating gear 5B and the crankshaft 4. The 2 nd eccentric bearing 8B is formed in the same manner as the 1 st eccentric bearing 8A. That is, the 2 nd eccentric bearing 8B includes a plurality of rollers 101 and a retainer 102.
The plurality of rollers 101 are disposed between the inner peripheral surface of the shaft insertion hole 92 of the 2 nd oscillating gear 5B and the outer peripheral surface of the 2 nd eccentric portion 74 of the crankshaft 4. The plurality of rollers 101 are arranged at equal angular intervals around the 2 nd eccentric portion 74. The plurality of rollers 101 are formed in a cylindrical shape extending in the axial direction. Each roller 101 rolls on the inner peripheral surface of the shaft insertion hole 92 of the 2 nd oscillating gear 5B and the outer peripheral surface of the 2 nd eccentric portion 74.
The load lines of the 1 st main bearing 6A and the 2 nd main bearing 6B will be described. The load acting line is a line extending from a midpoint of the central axis (rolling axis) of each of the rollers 63A and 63B so as to be orthogonal to the central axis.
As shown in fig. 2, a load acting line AL1 of the 1 st main bearing 6A passes through a position axially outward of the inner peripheral surface 62A of the inner ring 62A of the 1 st main bearing 6A. That is, the load acting line AL1 does not pass through the inner peripheral surface 62A of the inner ring 62A of the 1 st main bearing 6A. More specifically, the load acting line AL1 passes through the chamfered portion 62c of the inner race 62A.
The 1 st main bearing 6A has a contact angle θ of 40 ° or more and 50 ° or less, and is formed such that the 1 st main bearing 6A satisfies a relationship between at least one of the above formula (1) and the above formula (2). Thus, the load acting line AL1 passes through a position axially outward of the inner peripheral surface (the 1 st shaft support portion 42 and the enlarged diameter portion 44) of the 1 st main bearing mounting portion 32 of the 1 st carrier module 30. In the present embodiment, the load acting line AL1 passes through the axially outer side of the 1 st main bearing attachment portion 32. The load acting line AL1 passes through a position axially outward of the entire 1 st shaft attachment hole 41.
As shown in fig. 4, a load acting line AL2 of the 2 nd main bearing 6B passes through a position axially outward of the inner peripheral surface 62a of the inner ring 62B of the 2 nd main bearing 6B. More specifically, the load acting line AL2 passes through the chamfered portion 62c of the inner race 62B. The load acting line AL2 passes through the 2 nd main bearing mounting portion 51 at a position axially outward of the 2 nd inner ring holding portion 52 on the inner peripheral surface.
As described above, in the present embodiment, the load acting line AL1 of the 1 st main bearing 6A does not pass through the inner peripheral surface 62A of the inner ring 62A. According to this configuration, it is possible to avoid the load acting line AL1 passing through the wall of the member having the outer peripheral surface that holds the inner peripheral surface 62A of the inner ring 62A, that is, the wall of the 1 st main bearing attachment portion 32 of the carrier 3 that supports the 1 st main bearing 6A, so as to cross in the radial direction. This suppresses deformation of the wall of the 1 st main bearing mounting portion 32 so as to deflect inward in the radial direction, and can reduce the load applied to the 1 st main bearing mounting portion 32. Thus, the thickness of the 1 st main bearing mounting portion 32 can be reduced.
Further, the speed reducer 1 of the present embodiment includes the 1 st main bearing 6A described above, and the load acting line AL1 does not pass through the inner peripheral surface of the 1 st shaft mounting hole 41 of the 1 st main bearing mounting portion 32. With this configuration, it is possible to avoid the load acting line AL1 from passing through the outer peripheral surface (the 1 st inner ring holding portion 33) of the 1 st main bearing mounting portion 32 and the inner peripheral surface of the 1 st shaft mounting hole 41. This suppresses deformation of the thin portion formed between the outer peripheral surface of the 1 st main bearing mounting portion 32 and the inner peripheral surface of the 1 st shaft mounting hole 41 so as to be bent inward in the radial direction, and can reduce the load applied to the 1 st main bearing mounting portion 32. Therefore, the reduction in size of the speed reducer 1 due to the reduction in thickness of the 1 st main bearing mounting portion 32 can be achieved. In addition, the diameter of the 1 st shaft mounting hole 41 can be increased.
The 1 st main bearing 6A may be formed such that the load acting line AL1 passes through the end surface 62b of the inner ring 62A. According to this configuration, since load acting line AL1 does not pass through 1 st main bearing attachment 32 of carrier 3 that supports 1 st main bearing 6A, the load applied to 1 st main bearing attachment 32 can be reduced. Therefore, deformation of the 1 st main bearing mounting portion 32 is suppressed, and thus the thickness of the 1 st main bearing mounting portion 32 can be reduced.
Here, the relationship between the contact angle of the 1 st main bearing, the life of the reduction gear, and the rigidity of the reduction gear in the reduction gear of the embodiment will be described. The speed reducer of the embodiment corresponds to the speed reducer 1 of the above embodiment, and the contact angle of the 1 st main bearing is changed by appropriately changing the shape of the outer rolling surface 61c of the outer ring 61A of the 1 st main bearing 6A, the shape of the inner rolling surface 62d of the inner ring 62A, and the shape of the rollers 63. In the case of the 1 st main bearing of example, the load acting line passes through the axially outer side of the inner circumferential surface of the inner ring when the contact angle is 40 ° or more. Further, the load acting line passes through the end face of the inner ring when the contact angle is 45 ° or more.
Fig. 5 is a graph showing a relationship between a contact angle, a lifetime, and rigidity of the 1 st main bearing of the reduction gear according to the embodiment. In fig. 5, the horizontal axis represents the contact angle of the 1 st main bearing, the 1 st vertical axis on the left side represents the life of the reduction gear, and the 2 nd vertical axis on the right side represents the rigidity of the reduction gear.
As shown in fig. 5, at least in the range where the contact angle of the 1 st main bearing is 30 ° or more and 60 ° or less, the life of the reducer is extended as the contact angle of the 1 st main bearing increases. In addition, at least in a range where the contact angle of the 1 st main bearing is 30 ° or more and 60 ° or less, the rigidity of the reducer increases as the contact angle of the 1 st main bearing decreases. By setting the contact angle of the 1 st main bearing 6A to 40 ° or more and 50 ° or less, both the life and rigidity of the speed reducer 1 can be ensured with good balance.
Further, since the 1 st main bearing 6A satisfies the relationship of the above equation (1), the load acting line AL1 can pass through the position axially outward of the 1 st main bearing mounting portion 32. Therefore, the load applied to the 1 st main bearing mounting portion 32 can be reduced.
Further, since the 1 st main bearing 6A satisfies the relationship of the above equation (2), the load acting line AL1 can pass through the position axially outward of the 1 st main bearing mounting portion 32. Therefore, the load applied to the 1 st main bearing mounting portion 32 can be reduced.
In addition, the speed reducer 1 includes a 1 st crank bearing 7A having a roller 81. The roller 81 rolls on the 1 st shaft support portion 42 on the inner peripheral surface of the 1 st shaft mounting hole 41. According to this configuration, since the 1 st main bearing mounting portion 32 in which the 1 st shaft mounting hole 41 is formed can function as the outer ring of the 1 st crank bearing 7A, the outer ring which is a separate component can be omitted, and at least one of reduction in the diameter of the 1 st main bearing mounting portion 32 and reduction in the diameter of the 1 st shaft mounting hole 41 can be achieved in accordance therewith. The same applies to the 2 nd crank bearing 7B.
In addition, although the operational effects related to the 1 st main bearing 6A have been mainly described above, the same operational effects are also exerted with respect to the 2 nd main bearing 6B. The 1 st main bearing 6A is disposed closer to the mounting surface 30a of the carrier 3 than the 2 nd main bearing 6B. Therefore, the moment applied to the 1 st main bearing 6A is larger than the moment applied to the 2 nd main bearing 6B, and the above-described operational effect can be obtained to a large extent for the 1 st main bearing 6A.
The present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the 1 st crank bearing 7A is a needle bearing and the main bearing mounting portion 32 functions as an outer ring, but an outer ring may be provided as a separate member. The same applies to the 2 nd crank bearing 7B. The 1 st and 2 nd crankshaft bearings are not limited to the needle bearings, and at least either of them may be a tapered roller bearing, for example.
In the above embodiment, the case where the carrier 3 is used as the output shaft is described as an example, but the present invention is not limited thereto. That is, it is also possible to fixedly provide the carrier 3 and use the case 2 as the output shaft.
In addition, the components of the above-described embodiments may be replaced with known components as appropriate within a range not departing from the gist of the present invention.
(attached note 1)
A bearing, wherein,
the bearing includes:
an outer ring which is formed in an annular shape with a predetermined axis as a center and has an outer rolling surface facing a 1 st side in an axial direction along the axis and facing an inner side in a radial direction;
an inner ring that is disposed coaxially with the outer ring and has an inner rolling surface facing the 2 nd side in the axial direction and facing the outer side in the radial direction and an inner circumferential surface extending in the axial direction with a constant inner diameter; and
a plurality of rollers rolling on the inner rolling surface and the outer rolling surface,
the load acting line passes through the 1 st side in the axial direction with respect to the inner peripheral surface.
(attached note 2)
A bearing, wherein,
the bearing includes:
an outer ring which is formed in an annular shape with a predetermined axis as a center and has an outer rolling surface facing a 1 st side in an axial direction along the axis and facing an inner side in a radial direction;
an inner ring disposed coaxially with the outer ring and having an inner rolling surface facing the 2 nd side in the axial direction and facing the outer side in the radial direction and an end surface facing the 1 st side in the axial direction; and
a plurality of rollers rolling on the inner rolling surface and the outer rolling surface,
the load line of action passes through the end face of the inner race.

Claims (7)

1. A bearing, wherein,
the bearing includes:
an outer ring;
an inner ring having an inner peripheral surface and an axial end surface; and
and a rolling element disposed between the outer ring and the inner ring, and having a load line of action that does not pass through the inner circumferential surface.
2. A bearing, wherein,
the bearing includes:
an outer ring having a predetermined axis as a center;
an inner ring having an end surface in the direction of the axis; and
and a rolling element disposed between the outer ring and the inner ring, and having a load line passing through the end surface.
3. A speed reducer, wherein,
this reduction gear includes:
an outer member having an outer race;
an inner member having an inner ring and a bore for supporting the shaft member to be rotatable; and
and a bearing disposed between the outer ring and the inner ring and having a load acting line passing through an inner circumferential surface of the hole of the shaft hole.
4. A decelerator according to claim 3 wherein,
the contact angle of the bearing is 40 DEG or more and 50 DEG or less.
5. A decelerator according to claim 3 wherein,
a distance in the axial direction from an axial direction end surface of the inner ring to an intersection point where a surface of the inner ring intersects the load acting line is A,
the dimension of the whole of the inner ring and the outer ring in the axial direction is B,
the following relationship is satisfied:
0≤A/B≤0.2。
6. a decelerator according to claim 3 wherein,
a distance in the axial direction from an axial direction end surface of the inner ring to an intersection point where a surface of the inner ring intersects the load acting line is A,
the dimension of the inner race in the axial direction is B1,
the following relationship is satisfied:
0≤A/B1≤0.3。
7. a speed reducer, wherein,
this reduction gear includes:
a bearing, the bearing comprising: an outer ring formed in an annular shape and having an outer rolling surface facing radially inward; an inner ring disposed coaxially with the outer ring and having an inner rolling surface facing the radially outer side; and a plurality of rollers rolling on the inner rolling surface and the outer rolling surface;
an outer member to which the outer ring is attached;
an inner member having a bearing mounting portion to which the inner ring is mounted and the bearing mounting portion having a shaft hole;
a shaft member disposed in the shaft hole and rotatably supported by the inner member; and
a needle roller bearing interposed between the bearing mounting portion and the shaft member, the needle roller bearing having a plurality of rolling elements rolling on an inner circumferential surface of the shaft hole,
a load line of the bearing passes through the bearing mounting portion at a position on the outer side in the axial direction of the bearing than the inner peripheral surface of the shaft hole,
the contact angle of the bearing is 40 DEG or more and 50 DEG or less,
a is a distance in the axial direction from an outer end of the inner ring in the axial direction to an intersection point of a surface of the inner ring intersecting the load acting line,
b is the dimension of the whole of the inner ring and the outer ring in the axial direction,
when the dimension of the inner ring in the axial direction is B1, the following relationship is satisfied:
0 or more and A/B or less than 0.2, and
0≤A/B1≤0.3。
CN202010456071.8A 2019-06-27 2020-05-26 Bearing and speed reducer Pending CN112145557A (en)

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