reducer

Abstract

To reduce the size and weight of a speed reducer.SOLUTION: The speed reducer 100 includes: an internal gear 116 having a casing 122 encircling a main axis line 1La of the speed reducer and a plurality of outer pins 117 rotatably arranged in a pin groove 116b provided in the inner periphery of the casing; an external gear 114 meshing with the internal gear; an eccentric body 112 for oscillating the external gear; carriers 118, 120 to be rotated relative to the casing; and main bearings 124, 126 each having an inner periphery slide surface 148 to be rotated integrally with the casing and an outer periphery slide surface 149 to be rotated integrally with the carriers. One of the slide surfaces of the main bearings is made of resin, and the other is formed of a heat conductive material having higher wear resistance than the resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reducer. [Background technology]

[0002] Conventionally, there is known an eccentric oscillating reducer that reduces the rotational speed between two mating members at a predetermined reduction ratio. This eccentric oscillating reducer includes an outer cylinder fixed to one mating member, and a carrier disposed within the outer cylinder and fixed to the other mating member. The carrier rotates relative to the outer cylinder due to the oscillating rotation of an oscillating gear attached to an eccentric portion of a crankshaft.

[0003] In recent years, changes in the environment in which robots are used have led to a trend toward even smaller and lighter robots, which has resulted in demands for smaller and lighter reducers as well. As disclosed in Patent Document 1, in order to reduce the weight of the parts of the reducer, it is conceivable to use parts made of resin, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-17362 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 still has the problem of insufficient weight reduction. Furthermore, if the number of resin parts is increased to reduce weight using the technology described in Patent Document 1, the strength of the resin parts may become insufficient, which may increase the incidence of defects. Furthermore, when the temperature of the reducer rises during use, there is a problem that resin parts may suffer from problems such as deformation or malfunction.

[0006] The present invention aims to achieve an object of providing a reducer that can simultaneously achieve a reduction in weight and an improvement in rigidity. [Means for solving the problem]

[0007] Book A speed reducer according to one aspect of the present invention comprises: an internal gear having a casing (which serves as an internal gear main body) surrounding a main axis and a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing having an inner sliding surface that rotates integrally with the casing and an outer sliding surface that rotates integrally with the carrier; and One of the sliding surfaces of the main bearing is made of resin, and the other is made of a heat conductive material that has higher wear resistance than resin.

[0008] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear, which improves rigidity and heat dissipation while maintaining a small and lightweight design, thereby reducing the occurrence of failures.

[0009] Book A speed reducer according to one aspect of the present invention comprises: In the record Leave, In the main bearing, at least the inner sliding surface may be formed on the inner peripheral surface of the casing, or the outer sliding surface may be formed on the outer peripheral surface of the carrier.

[0010] Book A speed reducer according to one aspect of the present invention comprises: In the record Leave, The carrier may be made of resin, and the outer circumferential sliding surface may be formed on the outer circumferential surface of the carrier.

[0011] BookA speed reducer according to one aspect of the present invention comprises: In the record Leave, The inner sliding surface is made of a heat conductive material that is more wear-resistant than resin, The inner sliding surface may be disposed at a position overlapping the outer pin in a direction along the main axis.

[0012] (1) A speed reducer according to one aspect of the present invention includes an internal gear having a casing (which serves as an internal gear main body) surrounding a main axis and a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing having an inner sliding surface formed on an inner periphery of a metal ring that rotates integrally with the casing and an outer sliding surface formed on an outer periphery of the carrier; and the casing and the carrier are made of resin, The metal ring and the outer pin are arranged at a position where they overlap in a direction along the main axis.

[0013] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear to wrap with a metal ring, thereby further improving rigidity while maintaining a small and lightweight design and reducing the occurrence of failures.

[0014] (2) A reducer according to one aspect of the present invention includes: an internal gear provided on the inner periphery of a casing surrounding the main axis; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing having an inner sliding surface that rotates integrally with the casing and an outer sliding surface that rotates integrally with the carrier; and one of the sliding surfaces of the main bearing is made of resin, and the other is made of a heat conductive material that has higher wear resistance than resin; In the main bearing, at least one of the sliding surfaces is inclined in a direction along the main axis so as to increase or decrease a diameter dimension relative to the main axis.

[0015] According to a reducer according to one aspect of the present invention, the contact area of ​​the bearing surface of the sliding bearing can be increased, thereby improving operational stability.

[0016] (3) The reducer according to one aspect of the present invention is (2) In In the main bearing, a convex portion serving as a crushing margin can be formed on the sliding surface.

[0017] (4) The reducer according to one aspect of the present invention is (2) or (3) In In the main bearing, a groove that does not communicate with an internal space that houses the external gear may be formed in the sliding surface.

[0018] (5) A reducer according to one aspect of the present invention includes: an internal gear provided on the inner periphery of a casing surrounding the main axis; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing having an inner sliding surface formed on an inner peripheral surface of the casing and an outer sliding surface formed on an outer peripheral surface of the carrier; and the casing is made of metal and the carrier is made of resin; In the main bearing, the sliding surface is inclined so that a diameter dimension with respect to the main axis increases in a direction away from the external gear along the main axis, In the main bearing, a convex portion serving as a crushing margin is formed on the sliding surface, In the main bearing, a groove that does not communicate with the internal space that houses the external gear is formed on the sliding surface.

[0019] According to one aspect of the reducer of the present invention, dirt, excess grease, etc. can be contained in grooves on the sliding surface, preventing these from affecting the sliding condition on the sliding surface, and further preventing dirt, etc. from entering the interior of the reducer.

[0020] (6) A reducer according to one aspect of the present invention includes: An eccentric oscillating reducer that converts rotational speeds at a predetermined rotational speed ratio between a first member and a second member to transmit a driving force, an eccentric portion; an external gear having an insertion hole into which the eccentric portion is inserted and having external teeth; a casing configured to be attachable to one of the first member and the second member; a carrier configured to be attachable to the other of the first member and the second member; a main bearing having an inner sliding surface that rotates integrally with the casing and an outer sliding surface that rotates integrally with the carrier; Equipped with the casing has internal teeth that mesh with the external teeth of the external gear, the carrier is disposed radially inside the casing while holding the external gear, the casing and the carrier are concentrically rotatable relative to each other by oscillation of the external gear accompanying rotation of the eccentric portion, One of the sliding surfaces of the main bearing is made of resin, and the other is made of a heat conductive material that has higher wear resistance than resin.

[0021] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear, which improves rigidity and heat dissipation while maintaining a small and lightweight design, thereby reducing the occurrence of failures.

[0022] (7) A reducer according to one aspect of the present invention includes: An eccentric oscillating reducer having two or more eccentric bodies and external gears respectively corresponding to each eccentric body, a casing having an internal gear meshing with the external gear provided on its inner periphery; a carrier that rotates relative to the casing and the eccentric body; a main bearing having an inner sliding surface formed on an inner peripheral surface of the casing and an outer sliding surface formed on an outer peripheral surface of the carrier; and One of the sliding surfaces of the main bearing is made of resin, and the other is made of a heat conductive material that has higher wear resistance than resin.

[0023] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear, which improves rigidity and heat dissipation while maintaining a small and lightweight design, thereby reducing the occurrence of failures.

[0024] (8) A reducer according to one aspect of the present invention includes: an internal gear having a casing (which serves as an internal gear main body) surrounding a main axis and a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing disposed such that the outer pin is sandwiched between an inner peripheral surface that rotates integrally with the casing and an outer peripheral surface that rotates integrally with the carrier; and One of the inner circumferential surface, the outer circumferential surface and the outer pin is made of resin, and the other is made of a heat conductive material that is more wear-resistant than resin.

[0025] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear, which improves rigidity and heat dissipation while maintaining a small and lightweight design, thereby reducing the occurrence of failures.

[0026] (9) The reducer according to one aspect of the present invention is (8) In The outer pin may have an expanded diameter portion formed at one end (one end and / or the other end) thereof.

[0027] (10) A reducer according to one aspect of the present invention includes: an internal gear having a casing (which serves as an internal gear main body) surrounding a main axis and a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; one main bearing disposed such that the outer pin is sandwiched between an inner circumferential surface that rotates integrally with the casing and an outer circumferential surface that rotates integrally with the carrier; The other main bearing is configured as a cross roller bearing in which V-grooves having a V-shaped cross section facing each other are formed and a plurality of rollers are sandwiched between the V-grooves with axes perpendicular to each other; and and One of the inner circumferential surface, the outer circumferential surface and the outer pin is made of resin, and the other is made of a heat conductive material that is more wear-resistant than resin.

[0028] (11) A reducer according to one aspect of the present invention includes: an internal gear having a casing (which serves as an internal gear main body) surrounding a main axis and a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing disposed such that the outer pin is sandwiched between an inner peripheral surface that rotates integrally with the casing and an outer peripheral surface that rotates integrally with the carrier; and the inner peripheral surface and the outer peripheral surface are made of resin, and the outer pin is made of metal, An enlarged diameter portion having an enlarged diameter is formed at the end of the outer pin.

[0029] According to one aspect of the reducer of the present invention, an outer pin is used between the casing and the external gear, which improves rigidity and heat dissipation while maintaining a small and lightweight design, thereby reducing the occurrence of failures and improving operational reliability. [Effects of the Invention]

[0030] According to the present invention, it is possible to achieve the effects of improving rigidity and heat dissipation while maintaining a small and lightweight design, suppressing the occurrence of failures, and improving operational reliability. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a cross-sectional view taken along a main axis showing a first embodiment of a reducer according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line II-II in FIG. [Figure 3] FIG. 4 is a cross-sectional view taken along the main axis, showing a second embodiment of a reducer according to the present invention. [Figure 4] FIG. 10 is a cross-sectional view taken along the main axis, showing a third embodiment of a reducer according to the present invention. [Figure 5] 5 is a cross-sectional view taken along the arrows VV in FIG. 4. [Figure 6] FIG. 10 is a cross-sectional view taken along the main axis, showing a fourth embodiment of a reducer according to the present invention. [Figure 7] FIG. 10 is an enlarged cross-sectional view taken along the axial direction and showing the vicinity of a main bearing in a fifth embodiment of a reducer according to the present invention. [Figure 8] FIG. 13 is a cross-sectional view of a casing showing an inner sliding surface of a main bearing in a sixth embodiment of a reducer according to the present invention. [Figure 9] 13 is an enlarged cross-sectional view of a casing showing another example of the relationship between the crushed margin and the groove of the inner sliding surface in the sixth embodiment of the reducer according to the present invention. FIG. [Figure 10] 13 is a cross-sectional view of a casing showing another example of the relationship between the crushed margin and the groove of the inner sliding surface in the sixth embodiment of the reducer according to the present invention. FIG. [Figure 11] FIG. 10 is a cross-sectional view taken along the main axis, showing a seventh embodiment of a reducer according to the present invention. [Figure 12] 12 is a cross-sectional view taken along the arrows XII-XII in FIG. 11. [Figure 13] FIG. 13 is a cross-sectional view taken along the main axis, showing an eighth embodiment of a reducer according to the present invention. [Figure 14] FIG. 13 is a cross-sectional view taken along the main axis, showing a ninth embodiment of a reducer according to the present invention. [Figure 15] 15 is a cross-sectional view taken along the line XV-XV in FIG. 14. [Figure 16] FIG. 22 is a cross-sectional view taken along the main axis showing a tenth embodiment of a reducer according to the present invention. [Figure 17] FIG. 20 is a cross-sectional view taken along the main axis showing an eleventh embodiment of a reducer according to the present invention. [Figure 18] FIG. 23 is a cross-sectional view taken along the main axis showing a twelfth embodiment of a reducer according to the present invention. [Figure 19] FIG. 22 is a cross-sectional view taken along the main axis showing a thirteenth embodiment of a reducer according to the present invention. [Figure 20] FIG. 23 is a cross-sectional view taken along the main axis showing a fourteenth embodiment of a reducer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] A first embodiment of a reducer according to the present invention will be described below with reference to the drawings. Fig. 1 is a cross-sectional view taken along the main axis of a reducer according to this embodiment. Fig. 2 is a cross-sectional view taken along the line II-II in Fig. 1. The dimensions of the components in each drawing are enlarged or reduced as appropriate to facilitate understanding. Furthermore, some components that are not important for explaining the embodiment are omitted from each drawing. In the figure, reference numeral 100 denotes a speed reducer. In Fig. 2, for ease of understanding, one of the two external gears 114 is shown, and the other is not shown.

[0033] The reducer 100 of this embodiment is an eccentric oscillating reducer that causes rotation of one of the internal gear and the external gear by oscillating the external gear that meshes with the internal gear, and outputs the rotation component that has occurred from the output member to the driven device.

[0034] As shown in Figures 1 and 2, the eccentric oscillating type reducer 100 includes an input shaft 112, an external gear 114, an internal gear 116, carriers 118 and 120, a casing 122, main bearings 124 and 126, an inner pin 140, and a carrier pin 138. Hereinafter, the direction along the central axis (main axis) 1La of the internal gear 116 will be referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the central axis 1La will be referred to as the "circumferential direction" and the "radial direction," respectively. Also, hereinafter, for convenience, one side of the axial direction (the right side in FIG. 1) will be referred to as the input side, and the other side (the left side in FIG. 1) will be referred to as the counter-input side or output side.

[0035] The input shaft 112 is rotated about its rotational center line by rotational power input from a drive source. The reducer 100 of this embodiment is a center crank type in which the rotational center line of the input shaft 112 is coaxial with the central axis 1La of the internal gear 116. The drive source is, for example, a motor, a gear motor, an engine, etc.

[0036] The input shaft 112 is an eccentric shaft having a plurality of eccentric portions 112a for oscillating the external gear 114. An input shaft (eccentric body) 112 configured in this manner is sometimes called a crankshaft. The axis of the eccentric portions 112a is eccentric with respect to the rotation center line of the input shaft 112. In this embodiment, two eccentric portions 112a are provided, and the eccentric phases of adjacent eccentric portions 112a are shifted by 180°.

[0037] The input side of input shaft 112 is supported by second carrier 120 via input shaft bearing 134, and the non-input side is supported by first carrier (shaft flange) 118 via input shaft bearing 134. Input shaft 112 is supported so as to be freely rotatable relative to first carrier 118 and second carrier (hold flange) 120. There are no particular limitations on the configuration of input shaft bearing 134, but in this example it is a ball bearing with spherical rolling elements.

[0038] The internal gear 116 meshes with the external gear 114. The internal gear 116 of this embodiment shown in Figures 1 and 2 has an internal gear main body 116a integrated with the casing 122, and outer pins (internal pins) 117 arranged in pin grooves 116b formed at intervals in the circumferential direction of the internal gear main body 116a. The outer pins 117 are cylindrical or columnar pin members rotatably supported by the internal gear main body 116a. The outer pins 117 form the internal teeth of the internal gear 116. The number of outer pins 117 (the number of internal teeth) of the internal gear 116 is slightly more (by one in this example) than the number of external teeth of the external gear 114.

[0039] Basically, all of the outer pins 117 have the same shape. The diameter dimension of the outer pins 117 is set to be equal over the entire length in the direction along the central axis 1La. All of the outer pins 117 are arranged parallel to the central axis 1La. Furthermore, all of the outer pins 117 are arranged at the same position in the direction along the central axis 1La, at the same position in the radial direction, and at positions spaced apart from each other in the circumferential direction.

[0040] The casing 122 integrated with the internal gear body 116a is made of resin. Various resins can be used for the internal gear body 116a, but in this example, the casing 122 integrated with the internal gear body 116a is made of POM (polyacetal). The internal gear body 116a may also be made of a resin other than POM, such as PAEK (Polyaryletherketones), typified by PEEK (polyetheretherketone).

[0041] The resin used for the casing 122 integral with the internal gear body 116a and the other components of this embodiment may be a resin containing reinforcing fibers such as glass fiber or carbon fiber, a resin containing no reinforcing fibers, or a resin impregnated into a base material such as paper or cloth and laminated therewith. The resin used for each component of this embodiment may be a resin blended with a thermally conductive filler.

[0042] In the reducer 100, the outer pins 117 may be made of a material that has a higher thermal conductivity [W / (m·K)] and higher wear resistance than the resin of the internal gear body 116a. Hereinafter, metals and the like will be mentioned as examples of thermally conductive materials having higher wear resistance than resins, but in this specification, the term "metal" includes the above-mentioned thermally conductive materials having higher wear resistance than resins.

[0043] The material constituting the outer pins 117 may be a material that has higher wear resistance and thermal conductivity than the resin of the internal gear body 116a, and may be a metal material, a resin with high thermal conductivity, a non-metallic material, etc. The outer pins 117 may be a resin containing carbon nanotubes (CNTs) or boron nitride nanotubes (BNNTs). The outer pins 117 of this embodiment shown in Figures 1 and 2 may be made of an iron-based metal such as bearing steel.

[0044] The outer pin 117 may be a solid member or a hollow member. The outer pin 117 may be a member with a multilayer structure in which a core material is wrapped with a surface material. For example, one of the core material and the surface material of the outer pin 117 may be an iron-based metal, and the other may be a copper-based or aluminum-based metal. In this case, it is possible to achieve both mechanical properties and thermal properties. As another example, one of the core material and the surface material of the outer pin 117 may be made of metal, and the other may be made of resin. The outer pin 117 may also be made of sintered metal.

[0045] The external gears 114 are individually provided corresponding to the multiple eccentric portions 112a. The external gears 114 are rotatably supported by the corresponding eccentric portions 112a via eccentric bearings 130. As shown in FIG. 2, the external gear 114 has ten through holes formed at equal intervals at positions offset from its axis. Of these, carrier pins 138 are inserted into and pass through three carrier pin holes 139 arranged at equal intervals of 120 degrees, and inner pins 140 are inserted into and pass through the remaining nine inner pin holes 141. These carrier pin holes 139 and inner pin holes 141 may have the same diameter.

[0046] The external gear 114 is made of resin, just like the internal gear body 116a. Various resins can be used for the external gear 114. The external gear 114 is disposed closer to the input shaft 112 than the internal gear body 116a. The external gear 114 is made of PEEK. The external gear 114 may also be made of a resin other than PEEK, such as POM.

[0047] The carrier pin hole 139 and the inner pin hole 141 are circular holes provided at the same radial position. Wave-shaped teeth are formed on the outer periphery of the external gear 114, and these teeth move while making contact with the internal gear 116, allowing the external gear 114 to oscillate within a plane normal to the central axis. An inner pin hole 141 through which an inner pin 140 passes is formed in the external gear 114. A gap is provided between the inner pin 140 and the inner pin hole 141 to provide play to absorb the oscillating component of the external gear 114. The inner pin 140 and the inner wall surface of the inner pin hole 141 come into partial contact.

[0048] The carriers 118, 120 are arranged on both axial sides of the external gear 114. The carriers 118, 120 include a first carrier (shaft flange) 118 arranged on the side of the external gear 114 opposite the input side, and a second carrier (hold flange) 120 arranged on the side of the external gear 114 on the input side. First carrier 118 and second carrier 120 are rotatably supported by casing 122 via first main bearing 124 and second main bearing 126. First carrier (shaft flange) 118 is rotatably supported by casing 122 via first main bearing 124. Second carrier (hold flange) 120 is rotatably supported by casing 122 via second main bearing 126.

[0049] The carriers 118, 120 are generally disk-shaped. The first carrier 118 rotatably supports the input shaft 112 via an input shaft bearing 134. The second carrier 120 rotatably supports the input shaft 112 via an input shaft bearing 134. The carrier pin 138 is connected to the first carrier (shaft flange) 118 and the second carrier (hold flange) 120 by a bolt 138a. The inner pin 140 is connected to the first carrier (shaft flange) 118 and the second carrier (hold flange) 120 by a bolt 140a made of, for example, an iron-based metal.

[0050] The first carrier 118 and the second carrier 120 are connected via carrier pins 138 and inner pins 140. The carrier pins 138 and inner pins 140 axially penetrate the multiple external gears 114 at positions radially offset from the axis of the external gears 114. In this example, the carrier pins 138 and inner pins 140 are provided separately from the carriers 118, 120, but some of these pins may be formed integrally as part of the carriers 118, 120.

[0051] One of first carrier 118 and casing 122 functions as an output member that outputs rotational power to a driven device, and the other functions as a fixed member that is fixed to an external member that supports reducer 100. The output member is rotatably supported by the fixed member via main bearings 124, 126. A driven member that is rotationally driven by reducer 100 may be connected by bolts or the like to the end face on the opposite input side of first carrier 118. Alternatively, a driven member that is rotationally driven by reducer 100 may be connected by bolts or the like to an outer peripheral flange of casing 122.

[0052] The casing 122 has a hollow cylindrical shape as a whole, and the internal gear 116 is provided on its inner periphery. A flange or the like may be provided on the outer periphery of the casing 122. The casing 122 is provided with a first metal ring 144 on the side opposite the input side of the casing 122, and a second metal ring 145 on the input side of the casing 122. The first metal ring 144 and the second metal ring 145 are fixed integrally with the casing 122. The first metal ring 144 and the second metal ring 145 may be fixed to the casing 122 by a plurality of bolts arranged in the circumferential direction.

[0053] The casing 122 has a recess that accommodates the first metal ring 144. The first metal ring 144 protrudes from the recess in the axial direction. In the casing 122, the first metal ring 144 serves as an outer ring of the first main bearing 124. The outer periphery of the first metal ring 144 may be flush with the outer periphery of the casing 122.

[0054] A first metal ring 144, which serves as the outer ring of the first main bearing 124, is located on the output side of the casing 122. The first metal ring 144 is exposed on the output side of the casing 122. The portion of the first metal ring 144 that protrudes in the axial direction beyond the recess forms an inner circumferential sliding surface 148, which serves as the outer ring. The inner circumferential sliding surface 148 of the first metal ring 144 is in contact with the first carrier (shaft flange) 118. The first metal ring 144 is fixed to the casing 122 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0055] The casing 122 has a recess that accommodates the second metal ring 145. The second metal ring 145 protrudes from the recess in the axial direction. In the casing 122, the second metal ring 145 serves as an outer ring of the second main bearing 126. The outer periphery of the second metal ring 145 may be flush with the outer periphery of the casing 122.

[0056] A second metal ring 145, which serves as the outer ring of the second main bearing 126, is located on the input side of the casing 122. The second metal ring 145 is exposed on the input side of the casing 122. The portion of the second metal ring 145 that protrudes in the axial direction beyond the recess forms an inner circumferential sliding surface 148, which serves as the outer ring. The inner circumferential sliding surface 148 of the second metal ring 145 is in contact with the second carrier (hold flange) 120. The second metal ring 145 is fixed to the casing 122 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0057] The main bearings 124, 126 include a first main bearing 124 disposed between the first carrier 118 and the casing 122, and a second main bearing 126 disposed between the second carrier 120 and the casing 122. The main bearings 124, 126 of the present embodiment shown in Figures 1 and 2 are plain bearings. The main bearings 124, 126 each have an inner sliding surface 148 that serves as an outer ring and an outer sliding surface 149 that serves as an inner ring. The outer circumferential sliding surface 149 is provided on the outer circumferential surfaces of the carriers 118 and 120 which are integrated with the inner rings. The inner circumferential sliding surface 148 which becomes the outer ring is provided on the inner circumferential surfaces of the metal rings 144 and 145.

[0058] The inner sliding surface 148 that forms the outer ring of the main bearings 124, 126 is made of a material with higher thermal conductivity than the resin of the carriers 118, 120 that forms the outer sliding surface 149 that forms the inner ring.

[0059] In the main bearings 124, 126, the material constituting the metal rings 144, 145 that form the outer rings may be a metal material, a non-metal material, or the like, as long as it has a higher thermal conductivity than the resin of the carriers 118, 120 that form the inner rings, and is stronger than the resin of the carriers 118, 120. The metal rings 144, 145 of the present embodiment shown in Figures 1 and 2 may be made of a copper-based or aluminum-based metal, or an iron-based metal such as bearing steel.

[0060] The metal rings 144, 145 may be solid or hollow members. The metal rings 144, 145 may be multi-layered members in which a core material is wrapped with a surface material that forms the inner sliding surface 148. For example, one of the core material and the surface material of the metal rings 144, 145 may be an iron-based metal, and the other may be a copper-based or aluminum-based metal. As another example, the metal rings 144, 145 may be made of sintered metal.

[0061] In the main bearings 124 and 126, the sliding surfaces 148 and 149 of the first metal ring 144 and the second metal ring 145 are located radially outward of the outer pin 117. 1, the first metal ring 144 and the second metal ring 145 are both arranged so that the outer pin 117 overlaps with them in the axial direction. The first metal ring 144, the second metal ring 145 and the outer pin 117 overlap with each other in the axial direction, and this allows the strength of the casing 122 to be maintained over the entire length in the axial direction.

[0062] The inner pin 140 is inserted into and passes through the inner pin hole 141 formed through the external gear 114 with a gap therebetween. One end of the inner pin 140 is fitted into the recess 118b of the first carrier 118, and the other end is fitted into the recess 120b of the second carrier 120. The inner pin 140 is fixed to the recesses 118b, 120b with a bolt 140a. The inner pin 140 may be press-fitted into the recesses 118b, 120b, in which case it does not need to be fixed with a bolt or the like. The inner pin 140 abuts and contacts a part of the inner pin hole 141 formed in the external gear 114, restricting the rotation of the external gear 114 and allowing only its oscillation. The inner pin 140 functions as a connecting member that contributes to the transmission of power between the first carrier 118, the second carrier 120, and the external gear 114.

[0063] The carrier pin 138 is inserted with a gap into the carrier pin hole 139 formed through the external gear 114. One end of the carrier pin 138 is fitted into the recess 118c of the first carrier 118, and the other end is fitted into the recess 120c of the second carrier 120. The carrier pin 138 is fixed to the recesses 118c, 120c with a bolt 138a. The carrier pin 138 may be press-fitted into the recesses 118c, 120c, in which case it is not fixed with a bolt or the like. The carrier pin 138 does not contact the carrier pin hole 139 of the external gear 114 and does not contribute to restricting the rotation of the external gear 114. The carrier pin 138 functions as a connecting member that contributes only to the connection between the first carrier 118 and the second carrier 120.

[0064] The use of reducers is expanding to collaborative robots that operate close to people. To expand the range of applications, it is desirable to reduce the weight and noise of reducers. Conventional reducers are made up of components made of iron-based metals, and one way to reduce weight is to form the components from materials with low specific gravity. Resin is a suitable example of such a material. However, if the components are made of resin, it is thought that the temperature will rise due to reduced heat dissipation, resulting in a shorter lifespan. For this reason, it is desirable to select the material for each component taking into consideration weight reduction and heat dissipation. In this case, it is necessary to avoid a decrease in strength that accompanies weight reduction.

[0065] In the reducer 100, a large amount of heat is often generated inside, particularly around the main bearings 124 and 126, which are sliding bearings. Also, a large amount of heat is often generated around the input shaft 112, which rotates at a relatively high speed. Furthermore, if the inner pin 140 and the external gear 114 do not maintain sufficient strength, malfunction of the reducer 100 may occur. In this way, if the heat generated inside the reducer is not dissipated to the outside properly, the temperature rise of the reducer will be rapid. As the temperature of resin components rises, their rigidity and strength decrease rapidly, and if they continue to be used in this state, there is a high possibility that they will malfunction.

[0066] For this reason, when one of the components that move relative to each other is made of a resin material, it is desirable to make the other out of a material that has higher wear resistance and thermal conductivity [W / (m·K)] than the resin material. In this case, the heat generated inside can be dissipated to the outside more efficiently than if the other component had a lower thermal conductivity. At the same time, the component's lifespan can be extended compared to components with lower wear resistance.

[0067] The material constituting the inner sliding surface 148 of the outer ring may be a metal, nonmetal, or highly thermally conductive material, as long as it has higher wear resistance and thermal conductivity than the resin of the internal gear main body 116a, which forms the outer sliding surface 149 of the inner ring. In the present embodiment shown in FIGS. 1 and 2, the first metal ring 144, the second metal ring 145, and the outer pin 117 constituting the inner sliding surface 148 of the outer ring may be made of an iron-based metal such as bearing steel, an aluminum-based metal, a light metal such as aluminum, magnesium, beryllium, or titanium, or a composite material thereof. Alternatively, the first metal ring 144, the second metal ring 145, and the outer pin 117 may be made of ceramics or the like. By forming the carriers 118, 120 and other components from resin, the reducer 100 can be made both lighter and with higher mechanical strength.

[0068] High-speed rotation before deceleration is input to the input shaft 112 and the input shaft bearing 134 disposed between the first carrier 118 and the input shaft 112. Therefore, their temperature rise is relatively large, and if their heat resistance is low, the allowable input rotation speed will be low. Therefore, the input shaft bearing 134, the input shaft 112, and the eccentric bearing 130 may be made of a metal such as an iron-based metal. In this case, the decrease in the allowable input rotation speed can be suppressed. Because the input shaft 112 is subjected to large torsional stress, it is desirable for the input shaft 112 to be made of a material with higher rigidity than the first carrier 118. The input shaft 112 may be made of aluminum or an iron-based metal with higher torsional strength than aluminum. The iron-based metal may be carbon steel, bearing steel, stainless steel, or the like, depending on the desired characteristics.

[0069] To ensure the strength of the connection between the first carrier 118 and the second carrier 120, it is desirable that the rigidity of the carrier pin 138 be high. From this perspective, the carrier pin 138 may be made of metal. In this example, the carrier pin 138 is made of a material that has higher wear resistance and thermal conductivity than resin, for example, a metal such as aluminum.

[0070] The operation of the reducer 100 configured as above will be described. When rotational power is transmitted from the drive device to the input shaft 112, the eccentric portion 112a of the input shaft 112 rotates around a rotation center line passing through the input shaft 112, and the eccentric portion 112a causes the external gear 114 to oscillate. At this time, the external gear 114 oscillates so that its own axis rotates around the rotation center line of the input shaft 112. When the external gear 114 oscillates, the meshing positions of the external gear 114 and the outer pins 117 of the internal gear 116 are sequentially shifted. As a result, with each rotation of the input shaft 112, rotation of one of the external gear 114 and the internal gear 116 occurs by an amount corresponding to the difference between the number of teeth of the external gear 114 and the number of outer pins 117 of the internal gear 116. In the present embodiment shown in FIGS. 1 and 2 , the rotation of the external gear 114 causes reduced rotation to be output from the first carrier 118 or the casing 122.

[0071] In the reducer 100 of this embodiment shown in Figures 1 and 2, metal rings 144, 145 are used as the main bearings 124, 126, and the first carrier 118 and second carrier 120, which account for the main weight of the reducer 100, are made of resin, thereby making it possible to reduce the weight.

[0072] In the reducer 100 of this embodiment shown in Figures 1 and 2, the metal rings 144, 145 on which the inner sliding surfaces 148 that serve as the outer rings of the main bearings 124, 126 are formed are made of a material that is more wear-resistant and has a higher thermal conductivity than the resin of the carriers 118, 120 on which the outer sliding surfaces 149 are formed, and the metal rings 144, 145 and the outer pin 117 are arranged so as to overlap in the axial direction. In this case, compared to when the outer pins 117 do not come into contact with the metal rings 144, 145, the thermal resistance between the inner sliding surface 148 and the outer sliding surface 149 is reduced, and the internal heat can be dissipated more efficiently via the metal rings 144, 145 and the outer pins 117. As a result, the rise in internal temperature can be further suppressed.

[0073] 1 and 2, as described above, the first metal ring 144, the second metal ring 145, and the outer pin 117 are configured to overlap in the axial direction, thereby maintaining strength over the entire axial length of the casing 122. Therefore, because the first metal ring 144, the second metal ring 145, and the outer pin 117 overlap in the axial direction, deformation of the casing 122 and deformation of the carriers 118, 120 can be prevented, and sufficient strength can be maintained to prevent malfunction of the external gear 114.

[0074] In the present embodiment shown in FIGS. 1 and 2, the outer pins 117 are made of metal or the like, so that sufficient strength can be maintained to prevent malfunction of the external gear 114. In the main bearings 124, 126, the inner sliding surface 148 and the outer sliding surface 149 do not overlap with the outer pin 117 in the axial direction, but are arranged substantially continuously in the axial direction. This allows the thickness of the reducer 100 to be reduced, that is, the dimension in the direction of the central axis 1La to be reduced, thereby achieving miniaturization, while maintaining the strength of the reducer 100.

[0075] The inner sliding surfaces 148 of the first metal ring 144 and the second metal ring 145 are positioned radially adjacent to the outer pin 117. In the present embodiment shown in Figures 1 and 2, this configuration allows heat transferred from the main bearings 124 and 126, which are sliding bearings, to the first metal ring 144 and the second metal ring 145 to be dissipated to the outside, improving heat dissipation.

[0076] On the sliding surfaces 148 and 149, excessive temperature rise can cause the resin on the surface to melt or stick together, which can lead to malfunctions. However, by improving heat dissipation in this way, heat will not build up in the reducer 100, preventing malfunctions. Furthermore, by making the outer pins 117 out of metal or the like, heat transferred from the vicinity of the main bearings 124, 126 can be released, preventing local temperature rises, and improving heat dissipation.

[0077] At the same time, because the main bearings 124, 126 are formed by the metal rings 144, 145 and the carriers 118, 120, it is possible to reduce the number of heavy metal parts compared to configurations such as ball bearings or roller bearings, etc. This makes it possible to achieve further weight reduction while maintaining the heat dissipation capabilities and configuration of the reducer 100.

[0078] A second embodiment of a reducer according to the present invention will be described below with reference to the drawings. FIG. 3 is a cross-sectional view taken along the main axis direction of a reducer according to this embodiment. This embodiment differs from the first embodiment described above in terms of the main bearing. Other configurations corresponding to those of the first embodiment described above are assigned the same reference numerals, and descriptions thereof will be omitted.

[0079] 3, in the reducer 100 of this embodiment, the first metal ring 144 of the first main bearing 124 is provided on the first carrier (shaft flange) 118. The first metal ring 144 has an outer periphery on which an outer periphery sliding surface 149 of the main bearing 124 is formed. The first carrier (shaft flange) 118 has a recess that accommodates the first metal ring 144. The first metal ring 144 is disposed adjacent to the outer pin 117 in the axial direction. In the first carrier (shaft flange) 118, the first metal ring 144 serves as the inner ring of the first main bearing 124. The outer periphery of the first metal ring 144 may be flush with the outer periphery of the first carrier (shaft flange) 118.

[0080] A first metal ring 144, which serves as the inner ring of the first main bearing 124, is located on the input side of the first carrier (shaft flange) 118. The outer peripheral portion of the first metal ring 144, which is flush with the outer periphery of the first carrier (shaft flange) 118, forms an outer peripheral sliding surface 149, which serves as the inner ring. The outer peripheral sliding surface 149 of the first metal ring 144 is in contact with the casing 122. The first metal ring 144 is fixed to the first carrier (shaft flange) 118 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0081] The inner peripheral surface of casing 122 that contacts outer peripheral sliding surface 149 forms inner peripheral sliding surface 148 that becomes the outer ring of first main bearing 124. The outer ring of first main bearing 124 is configured integrally with casing 122.

[0082] 3, in the reducer 100 of this embodiment, the second metal ring 145 of the second main bearing 126 is provided on the second carrier (hold flange) 120. The second metal ring 145 has an outer periphery on which an outer periphery sliding surface 149 of the main bearing 126 is formed.

[0083] The second carrier (hold flange) 120 has a recess that accommodates a second metal ring 145. The second metal ring 145 is disposed adjacent to the outer pin 117 in the axial direction. In the second carrier (hold flange) 120, the second metal ring 145 serves as an inner ring of the second main bearing 126. The outer periphery of the second metal ring 145 may be flush with the outer periphery of the second carrier (hold flange) 120.

[0084] A second metal ring 145, which serves as the inner ring of the second main bearing 126, is located on the output side of the second carrier (hold flange) 120. The outer periphery of the second metal ring 145, which is flush with the outer periphery of the second carrier (hold flange) 120, forms an outer periphery sliding surface 149, which serves as the inner ring. The outer periphery sliding surface 149 of the second metal ring 145 contacts the casing 122. The second metal ring 145 is fixed to the second carrier (hold flange) 120 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0085] The inner peripheral surface of casing 122 that contacts outer peripheral sliding surface 149 forms inner peripheral sliding surface 148 that becomes the outer ring of first main bearing 124. The outer ring of first main bearing 124 is configured integrally with casing 122. The metal rings 144, 145 of the main bearings 124, 126 may be configured to cover the entire axial length of the outer periphery of the carriers 118, 120.

[0086] In the reducer 100 of this embodiment shown in Figure 3, the sliding surfaces 148, 149 are made of resin and metal, respectively, so it is possible to achieve the same effects as the first embodiment shown in Figures 1 and 2 described above.

[0087] A third embodiment of a reducer according to the present invention will be described below with reference to the drawings. Fig. 4 is a cross-sectional view taken along the main axis direction of the reducer of this embodiment, and Fig. 5 is a cross-sectional view taken along the line VV in Fig. 4. In the figure, reference numeral 200 denotes the reducer.

[0088] The reducer 200 of this embodiment is an eccentric oscillating type reducer that causes rotation of one of the internal gear and the external gear by oscillating the external gear that meshes with the internal gear, and outputs the generated rotation component from the output member to the driven device.

[0089] As shown in FIGS. 4 and 5, the reducer 200 of this embodiment differs in that one of the two external gears 214 has a phase difference of 180 degrees with respect to the other external gear 214, but the rest of the configuration is the same. 4 and 5, the reducer 200 of this embodiment includes an input shaft 212, an external gear 214, an internal gear 216, carriers 218 and 220, a casing 222, main bearings 224 and 226, an inner pin 240, and a carrier pin 238. Hereinafter, the direction along the central axis 2La of the internal gear 216 will be referred to as the "main axis direction," and the circumferential direction and radial direction of a circle centered on the central axis 2La will be referred to as the "circumferential direction" and the "radial direction," respectively. Furthermore, hereinafter, for convenience, one side of the axial direction (the right side in the drawings) will be referred to as the input side, and the other side (the left side in the drawings) will be referred to as the non-input side.

[0090] The input shaft 212 is rotated about its rotational center line by rotational power input from a drive device (not shown). The reducer 200 of this embodiment is a center crank type in which the rotational center line of the input shaft 212 is arranged coaxially with the central axis line 2La of the internal gear 216. The drive device is, for example, a motor, a gear motor, an engine, etc.

[0091] As shown in Figures 4 and 5, the input shaft 212 of this embodiment is an eccentric body shaft having multiple eccentric portions 212a for oscillating the external gear 214. An input shaft (eccentric body) 212 configured in this manner is sometimes called a crankshaft. The axis of the eccentric portions 212a is eccentric with respect to the rotation center line of the input shaft 212. In this embodiment, two eccentric portions 212a are provided, and the eccentric phases of adjacent eccentric portions 212a are shifted by 180°.

[0092] The input side of the input shaft 212 is supported by the second cover 223 via the input shaft bearing 234, and the non-input side is supported by the first carrier 218 via the input shaft bearing 234. In other words, the input shaft 212 is supported so as to be freely rotatable with respect to the first carrier 218 and the second cover 223. There are no particular limitations on the configuration of the input shaft bearing 234, but in this example, it is a ball bearing having spherical rolling elements. The input shaft bearing 234 may be pressurized, but in this example, no pressurization is applied.

[0093] The internal gear 216 meshes with the external gear 214. The internal gear 216 of this embodiment shown in Figures 4 and 5 has an internal gear main body 216a integrated with the casing 222, and outer pins (internal pins) 217 ​​arranged in pin grooves 216b formed at intervals in the circumferential direction in the internal gear main body 216a. The outer pins 217 are cylindrical pin members rotatably supported by the internal gear main body 216a. The outer pins 217 form the internal teeth of the internal gear 216. The number of outer pins 217 (the number of internal teeth) of the internal gear 216 is slightly more (by one in this example) than the number of external teeth of the external gear 214.

[0094] The internal gear body 216a is made of resin. Various resins can be used for the internal gear body 216a, but in this example, the internal gear body 216a is made of POM (polyacetal). The internal gear body 216a may also be made of a resin other than POM, such as PAEK (Polyaryletherketones), typified by PEEK (polyetheretherketone).

[0095] The resin used for the internal gear body 216a and other components of this embodiment may be a resin containing reinforcing fibers such as glass fiber or carbon fiber, a resin containing no reinforcing fibers, or a resin that is impregnated into a base material such as paper or cloth and then laminated. In particular, the resin used for each component of this embodiment may be a resin blended with a thermally conductive filler, and examples of such thermally conductive fillers include nano-order fillers, ceramic powders such as aluminum oxide and aluminum nitride, and metal powders such as aluminum, copper, and graphite.

[0096] The reducer 200 often generates a large amount of heat internally, particularly around the input shaft 212, which rotates at a relatively high speed. Thus, poor external heat dissipation of internally generated heat leads to a significant temperature rise in the reducer 200. Resin materials lose strength rapidly as their temperature rises, making them susceptible to breakage if used continuously. Therefore, when one of a pair of meshing gears is made of a resin material, it is desirable to construct the other gear from a material with a higher thermal conductivity [W / (m·K)] than the resin material. Therefore, in the eccentric oscillating reducer 200, the outer pins 217 are made from a material with a higher thermal conductivity than the resin of the internal gear body 216a. In this case, the heat generated internally is better dissipated externally than when the outer pins 217 have a low thermal conductivity.

[0097] The material constituting the outer pins 217 may be any material with a higher thermal conductivity than the resin of the internal gear body 216a, and may be a metal material, a highly thermally conductive resin, a non-metallic material, or the like. Examples of highly thermally conductive resins include resins blended with thermally conductive fillers. The outer pins 217 may also be resins blended with carbon nanotubes (CNTs) or boron nitride nanotubes (BNNTs). The outer pins 217 of this embodiment shown in Figures 4 and 5 are made of an iron-based metal such as bearing steel.

[0098] The outer pin 217 may be a solid member or a hollow member. The outer pin 217 may be a member with a multilayer structure in which a core material is wrapped with a surface material. As an example, one of the core material and the surface material of the outer pin 217 may be an iron-based metal, and the other may be a copper-based or aluminum-based metal. In this case, it is possible to achieve both mechanical properties and thermal properties. As another example, one of the core material and the surface material of the outer pin 217 may be made of metal, and the other may be made of resin. The outer pin 217 may also be made of sintered metal.

[0099] The external gears 214 are individually provided corresponding to the multiple eccentric portions 212a. The external gears 214 are rotatably supported by the corresponding eccentric portions 212a via eccentric bearings 230. The external gears 214 have 212 through holes formed at equal intervals at positions offset from the axis of the external gear 214. Of these, carrier pins 238 are inserted into and pass through three holes arranged at equal intervals of 120 degrees, and inner pins 240 are inserted into and pass through the remaining nine holes. Therefore, the former are referred to as carrier pin holes 239, and the latter are referred to as inner pin holes 241. These holes may have the same diameter, but in this example, the diameter of the carrier pin holes 239 is larger than the diameter of the inner pin holes 241.

[0100] The external gear 214 is made of resin. Various resins can be used for the external gear 214. In particular, since the external gear 214 is disposed near the input shaft 212, which experiences a large temperature rise, the external gear 214 may be made of a resin that has a higher heat resistance temperature than the internal gear main body 216a. From this perspective, the external gear 214 is made of PEEK. The external gear 214 may also be made of a resin other than PEEK, such as POM.

[0101] The carrier pin hole 239 and the inner pin hole 241 are circular holes provided at the same radial position. Wave-shaped teeth are formed on the outer periphery of the external gear 214, and these teeth move while making contact with the internal gear 216, allowing the external gear 214 to oscillate within a plane normal to the central axis. An inner pin hole 241 through which an inner pin 240 passes is formed in the external gear 214. A gap is provided between the inner pin 240 and the inner pin hole 241 to provide play for absorbing the oscillating component of the external gear 214. The inner pin 240 and the inner wall surface of the inner pin hole 241 come into partial contact.

[0102] The carriers 218, 220 are disposed on axial sides of the external gear 214. The carriers 218, 220 include a first carrier (shaft flange) 218 ​​disposed on the side opposite the input side of the external gear 214, and a second carrier (hold flange) 220 disposed on the side of the input side of the external gear 214. The first carrier 218 and the second carrier 220 are rotatably supported on a casing 222 via a first main bearing 224 and a second main bearing 226. The carriers 218, 220 are generally disk-shaped. The first carrier 218 rotatably supports the input shaft 212 via an input shaft bearing 234. The second carrier 220 may be configured to support the input shaft via an input shaft bearing, but in this example, it does not support the input shaft bearing 234 or the input shaft 212.

[0103] The first carrier 218 and the second carrier 220 are connected via carrier pins 238 and inner pins 240. The carrier pins 238 and inner pins 240 axially penetrate the plurality of external gears 214 at positions radially offset from the axis of the external gears 214. In this example, the carrier pins 238 and inner pins 240 are provided separately from the carriers 218, 220, but some of these pins may be formed integrally as part of the carriers 218, 220.

[0104] One of the first carrier 218 and the casing 222 functions as an output member that outputs rotational power to a driven device, and the other functions as a fixed member that is fixed to an external member for supporting the reducer 200. The output member is rotatably supported by the fixed member via main bearings 224 and 226. In the present embodiment shown in FIGS. 4 and 5, the output member is the first carrier 218, and the fixed member is the casing 222. A driven member 250 that is rotationally driven by the reducer 200 is connected to an end face of the first carrier 218 on the opposite input side by a bolt 250b. The bolt 250b in the present embodiment shown in FIGS. 4 and 5 may be made of an iron-based metal.

[0105] The casing 222 has a hollow cylindrical shape overall, and the internal gear 216 is provided on its inner periphery. A flange or the like may be provided on the outer periphery of the casing 222, but no flange is provided in this example. The casing 222 is provided with a first cover 221 that covers the non-input side of the casing 222, and a second cover 223 that covers the input side of the casing 222. The first cover 221 and the second cover 223 are fixed to the casing 222 by a plurality of bolts arranged in the circumferential direction.

[0106] The casing 222 is provided with a recess that accommodates the input side of the outer ring of the first main bearing 224. The first cover 221 is provided with a recess that accommodates a portion of the non-input side of the outer ring of the first main bearing 224. The outer ring of the first main bearing 224 is supported by being sandwiched axially between the casing 222 and the first cover 221. The casing 222 is provided with a recess that accommodates the non-input side of the outer ring of the second main bearing 226. The second cover 223 is provided with a recess that accommodates a portion of the input side of the outer ring of the second main bearing 226. The outer ring of the second main bearing 226 is supported by being sandwiched axially between the casing 222 and the second cover 223. The second cover 223 is provided with a recess that accommodates the outer ring of the input shaft bearing 234 on the input side. In other words, the second cover 223 rotatably supports the input side of the input shaft 212 via the input shaft bearing 234.

[0107] The main bearings 224, 226 include a first main bearing 224 arranged between the first carrier 218 and the casing 222, and a second main bearing 226 arranged between the second carrier 220 and the casing 222. In this embodiment shown in Figures 4 and 5, the main bearings 224, 226 each include metal rings 244, 245 that form an inner sliding surface 248. The metal ring 244 supports the carriers 218, 220 so that they can rotate freely.

[0108] The main bearings 224, 226 are sliding bearings and include metal rings 244, 245 that form an inner sliding surface 248 that serves as the outer ring, and an outer sliding surface 249 that serves as the inner ring. The outer sliding surface 249 that serves as the inner ring is provided on the outer peripheral surface of the carriers 218, 220. The metal rings 244, 245 that serve as the outer ring are fixed to the casing 222 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients. A preload may be applied to the main bearings 224, 226, but in this example, no preload is applied.

[0109] 4 and 5, the metal rings 244, 245 that form the outer rings of the main bearings 224, 226 are made of a material with a higher thermal conductivity than the resin of the internal gear body 216a, and the metal rings 244, 245 of the main bearings 224, 226 are in axial contact with the outer pin 217. As shown in Fig. 4, the ends of the metal rings 244, 245 and the end of the outer pin 217 may be configured to be in direct contact with each other. Furthermore, the ends of the metal rings 244, 245 and the ends of the outer pins 217 may be configured to contact each other in the axial direction via a spacer made of a material with higher thermal conductivity than the resin of the internal gear main body 216a. With this configuration, heat transferred to the outer pins 217 is dissipated to the carriers 218, 220, casing 222, etc. via the metal rings 244, 245, improving heat dissipation. Furthermore, heat transferred to the first carrier 218 is dissipated to the outside via the driven member 250, improving heat dissipation.

[0110] The material constituting the metal rings 244, 245 and the outer pin 217 may be a material with a higher thermal conductivity than the resin of the internal gear body 216a, and may be a metal material, a highly thermally conductive resin, or a non-metallic material. The metal rings 244, 245 and the outer pin 217 of the present embodiment shown in Figures 4 and 5 may be made of an iron-based metal such as bearing steel.

[0111] The material constituting the first carrier 218 may be any material with a higher thermal conductivity than the resin of the internal gear body 216a, and may be a metal material, a highly thermally conductive resin, or a non-metallic material. From the viewpoint of achieving both lightweight and mechanical strength, the first carrier 218 may be made of a light metal (a metal with a specific gravity of 4 or 5 or less), such as aluminum, magnesium, beryllium, or titanium, or a composite material thereof. The first carrier 218 of the present embodiment shown in FIGS. 4 and 5 is made of an aluminum-based metal. In this case, the first carrier 218 may be made of a metal material with a lower specific gravity than the input shaft 212.

[0112] The second carrier 220 can be made of metal or various resins. The second carrier 220 of the present embodiment shown in FIGS. 4 and 5 is made of POM. In this case, the weight of the second carrier 220 can be reduced. In order to reduce heat conduction from the input shaft bearing 234, the second carrier 220 is not in direct contact with the input shaft bearing 234 but is arranged with a gap therebetween. The second carrier 220 may also be made of a material with a higher thermal conductivity than the resin of the internal gear main body 216a. In this case, heat dissipation is further improved.

[0113] The inner pin 240 is inserted into and passes through an inner pin hole 241 formed through the external gear 214 with a gap therebetween. One end of the inner pin 240 is fitted into a recess 218b of the first carrier 218, and the other end is fitted into a recess 220b of the second carrier 220. The inner pin 240 is press-fit into the recesses 218b, 220b and is not fixed by bolts or the like. The inner pin 240 contacts a part of the inner pin hole 241 formed in the external gear 214, and restricts the rotation of the external gear 214, allowing only its oscillation. The inner pin 240 functions as a connecting member that contributes to the transmission of power between the first carrier 218 and the second carrier 220 and the external gear 214.

[0114] The carrier pin 238 is inserted with a gap into the carrier pin hole 239 formed through the external gear 214 and passes through it. One end of the carrier pin 238 is fitted into the recess 218c of the first carrier 218, and the other end is fitted into the recess 220c of the second carrier 220. The carrier pin 238 is press-fit into the recesses 218c, 220c and is not fixed by bolts or the like. The carrier pin 238 is surrounded by a tubular spacer 237. One end of the spacer 237 contacts the first carrier 218 and the other end contacts the second carrier 220. The spacer 237 functions as a spacer that maintains an appropriate distance between the first carrier 218 and the second carrier 220 in the axial direction. The carrier pins 238 and spacers 237 are not in contact with the carrier pin holes 239 of the external gear 214 and do not contribute to restricting the rotation of the external gear 214. The carrier pins 238 function as connecting members that contribute only to the connection between the first carrier 218 and the second carrier 220.

[0115] The materials constituting each of the components of this embodiment shown in Figures 4 and 5 are desirably selected with consideration given to weight reduction and heat dissipation. In recent years, the use of reducers has expanded to collaborative robots that operate in close proximity to humans. For this reason, there is a demand for reducers that are lighter and quieter. Conventional reducers are made up of components made of iron-based metals, and one way to reduce weight is to form the components from a material with a low specific gravity. Resin is a suitable example of such a material. However, if the components are made of resin, it is thought that the temperature will increase due to a decrease in heat dissipation, and the lifespan will be shortened.

[0116] High-speed rotation before deceleration is input to the input shaft 212 and the input shaft bearing 234, which is disposed between the first carrier 218 and the input shaft 212. Therefore, their temperature rise is relatively large, and if their heat resistance is low, the allowable input rotation speed will be low. For this reason, the input shaft bearing 234, the input shaft 212, and the eccentric bearing 230 may be made of a metal such as an iron-based metal. In this case, a decrease in the allowable input rotation speed can be suppressed. Because the input shaft 212 is subjected to large torsional stress, it is desirable for the input shaft 212 to be made of a material with higher rigidity than the first carrier 218. The input shaft 212 is made of an iron-based metal, which has higher torsional strength than aluminum. The iron-based metal used for each component of this embodiment shown in FIGS. 4 and 5 can be carbon steel, bearing steel, stainless steel, or the like, depending on the desired characteristics.

[0117] To ensure the connection strength between the first carrier 218 and the second carrier 220, it is desirable that the carrier pin 238 has high rigidity. From this perspective, the carrier pin 238 may be made of metal, and the spacer 237 may be made of resin to reduce weight. In this example, the carrier pin 238 is made of an iron-based metal, and the spacer 237 is made of POM. The casing 222 is integrated with the internal gear main body 216a and may be made of the same material as the internal gear main body 216a. From the perspective of reducing weight, the first cover 221 and the second cover 223 may be made of resin. They may be made of the same resin or different resins. The first cover 221 and the second cover 223 of the present embodiment shown in Figures 4 and 5 may be made of POM.

[0118] The operation of the reducer 200 will now be described. When rotational power is transmitted from the drive device to the input shaft 212, the eccentric portion 212a of the input shaft 212 rotates around a rotation center line passing through the input shaft 212, and the eccentric portion 212a causes the external gear 214 to oscillate. At this time, the external gear 214 oscillates such that its own axis rotates around the rotation center line of the input shaft 212. When the external gear 214 oscillates, the meshing positions of the external gear 214 and the outer pins 217 of the internal gear 216 are sequentially shifted. As a result, with each rotation of the input shaft 212, rotation of one of the external gear 214 and the internal gear 216 occurs by an amount corresponding to the difference between the number of teeth of the external gear 214 and the number of outer pins 217 of the internal gear 216. In this embodiment, the external gear 214 rotates on its axis, and reduced rotation is output from the first carrier 218.

[0119] In the reducer 200 of this embodiment shown in FIGS. 4 and 5, the main bearings 224, 226 do not include metal components heavier than resin other than the metal rings 244, 245, and therefore can be made even lighter.

[0120] In the present embodiment shown in FIGS. 4 and 5, it is possible to achieve the same effects as the above-described embodiments.

[0121] A fourth embodiment of the reducer according to the present invention will be described below with reference to the drawings. 6 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the first embodiment described above in terms of the main bearings, and other components corresponding to those of the first embodiment described above are assigned the same reference numerals in the 300s rather than the 100s, and their description will be omitted.

[0122] 6, in the reducer 300 of this embodiment, the casing 322 is integral with an inner sliding surface 348 that serves as the outer ring of the main bearings 324, 326, and the entire casing 322 is made of a heat conductive material that has higher wear resistance than the resin that makes up the outer sliding surface 349 that serves as the inner ring of the main bearings 324, 326. Specifically, the casing 322 is made of metal.

[0123] 6, in the reducer 300 of this embodiment, the inner sliding surface 348 and the outer sliding surface 349 are formed so that their diameters increase with increasing distance from the external gear 314 in the direction along the central axis 3La. The inner sliding surface 348 and the outer sliding surface 349 are formed so that the angle they form with respect to the central axis 3La is in the range of 30° to 60°. Furthermore, in the reducer 300 of this embodiment shown in Figure 6, the inner sliding surface 348 and the outer sliding surface 349 can be formed so that the angle they form with respect to the central axis 3La is in the range of 40° to 50°, more preferably 45°.

[0124] Alternatively, in the reducer 300 of this embodiment shown in Fig. 6, the angle that the inner sliding surface 348 and the outer sliding surface 349 make with respect to the central axis 3La can be set to 45° to 40°. In this configuration, the angle of the end faces (outer peripheral surfaces) of the first carrier (shaft flange) 318 and the second carrier (hold flange) 320 made of resin can be reduced, thereby suppressing deformation of these. In other words, it is possible to prevent the axial thickness of the first carrier (shaft flange) 318 and the second carrier (hold flange) 320 made of resin near their outer edges from becoming too thin.

[0125] 6, the casing 322 and the first carrier (shaft flange) 318 seal the internal space of the reducer 300 via a first main bearing 324. Similarly, the casing 322 and the second carrier (hold flange) 320 seal the internal space of the reducer 300 via a second main bearing 326. The external gear 314 and the outer pin (internal pin) 317 are housed in the internal space of the reducer 300. The main bearings 324 and 326 are sliding bearings, and the internal space of the reducer 300 is sealed by sliding surfaces 348 and 349 .

[0126] 6, a drive gear 313 that inputs a driving force to an input shaft (eccentric body) 312 is provided so as to be rotatable integrally with a drive shaft 313a. Note that a carrier pin 338 is not shown in the drawing.

[0127] According to the reducer 300 of this embodiment shown in Fig. 6, the casing 322 is entirely made of a heat-conductive material, such as metal, that is more wear-resistant than resin, so that heat generated in the main bearings 324, 326 can be transferred via the casing 322 and quickly dissipated to the outside. This effectively suppresses temperature increases in the reducer 300. At the same time, by configuring the components other than the casing 322, the inner pin 340, and the drive gear 313 from resin, the weight of the reducer 300 can be reduced. Furthermore, by making the casing 322 out of metal, it is possible to maintain sufficient strength and rigidity.

[0128] Furthermore, according to the reducer 300 of this embodiment shown in Fig. 6, the angle that the inner sliding surface 348 and the outer sliding surface 349 make with respect to the central axis 3La is set within the above-mentioned range, so that the areas of the inner sliding surface 348 and the outer sliding surface 349 can be increased without increasing the thickness of the reducer in the axial direction. At the same time, the casing 322, the first carrier (shaft flange) 318, and the second carrier (hold flange) 320 can be prevented from deformation, providing sufficient strength to prevent operational malfunctions. This prevents malfunctions and maintains operational stability.

[0129] Furthermore, in this embodiment shown in FIG. 6, it is possible to achieve the same effects as the above-described embodiments.

[0130] A fifth embodiment of a reducer according to the present invention will be described below with reference to the drawings. 7 is an enlarged axial cross-sectional view showing the vicinity of the main bearing in the reducer of this embodiment. This embodiment differs from the fourth embodiment in terms of the main bearing. Other components corresponding to those of the fourth embodiment are designated by the same reference numerals and will not be described further.

[0131] 7, in the reducer 300 of this embodiment, the inner sliding surface 348 and the outer sliding surface 349 of the main bearings 324, 326 bulge outward from each other in the direction along the main axis to form a convex portion. Alternatively, the inner sliding surface 348 and the outer sliding surface 349 bulge outward from only one side in the direction along the main axis to form a convex portion.

[0132] It is preferable that the inner sliding surface 348 and the outer sliding surface 349 be in contact with each other over their entire surfaces to increase the contact area and support the sliding, but this ideal state is not always possible due to distortions and other factors that occur during manufacturing. This can lead to malfunctions such as rattles, but to prevent this, squeezes are formed in the inner sliding surface 348 and the outer sliding surface 349 beforehand.

[0133] The crushed margins formed on inner sliding surface 348 and outer sliding surface 349 can be convex portions with curved cross sections, as shown in Fig. 7. With this configuration, the contact area between inner sliding surface 348 and outer sliding surface 349 can be reliably determined in advance within the range set by the crushed margins. This prevents non-contact states due to manufacturing errors and ensures that the contact area between inner sliding surface 348 and outer sliding surface 349 is in contact with the ridge near the center in the axial direction. This improves the operational stability of first carrier (shaft flange) 318 and second carrier (hold flange) 320 relative to casing 322. Also, it is possible to provide sufficient strength to prevent deformation of the casing 322, the first carrier (shaft flange) 318, and the second carrier (hold flange) 320, thereby preventing operational malfunctions. Furthermore, it is also possible to suppress temperature rise in the main bearings 324, 326.

[0134] Furthermore, in this embodiment shown in FIG. 7, it is possible to achieve the same effects as the above-described embodiments.

[0135] A sixth embodiment of a reducer according to the present invention will be described below with reference to the drawings. 8 is a cross-sectional view of the casing showing the inner sliding surface of the main bearing in the reducer of this embodiment. This embodiment differs from the fourth embodiment in terms of the main bearing. Other components corresponding to those of the fourth embodiment are given the same reference numerals and will not be described.

[0136] In the reducer 300 of this embodiment, as shown in FIG. 8, a groove 360 ​​is formed in the inner sliding surface 348 of the casing 322. The groove 360 ​​has, on the inner sliding surface 348, a radial groove (groove) 361 extending in the radial direction, and circumferential grooves (grooves) 362 and 363 extending in the circumferential direction. A plurality of radial grooves 361 are formed on the inner sliding surface 348 and are spaced apart from one another in the circumferential direction. The radial grooves 361 are spaced apart from one another in the circumferential direction. The radial grooves 361 may also be spaced apart from one another at equal distances in the circumferential direction.

[0137] The circumferential groove 362 is formed near the center of the inner sliding surface 348 in the axial direction. The circumferential groove 363 is formed in a position on the inner sliding surface 348 close to the external gear 314 in the axial direction. The radial groove 361 is not formed in a position closer to the external gear 314 than the circumferential groove 363 in the axial direction. Furthermore, the radial groove 361 is formed to the end of the inner sliding surface 348 in the direction away from the external gear 314 in the axial direction and continues to the outside.

[0138] Circumferential grooves 362, 363 extend around the inner sliding surface 348 in the circumferential direction. Radial groove 361 is connected to circumferential groove 363 so as to terminate at circumferential groove 363. No other grooves are formed on inner sliding surface 348 at a position closer to input shaft 312 than circumferential groove 363. In other words, groove 360 ​​is spaced apart from and does not contact outer pin 317. The depth and width of the grooves 360 may all be equal, or the circumferential grooves 362 and 363 may be larger than the radial groove 361 .

[0139] According to the reducer 300 of this embodiment shown in Fig. 8, foreign matter such as dust or particles that has entered between the inner sliding surface 348 and the outer sliding surface 349 is captured by the groove 360 ​​and does not enter the internal space of the reducer 300. In other words, it is possible to prevent foreign matter such as dust or particles from affecting the operation of the external gear 314, the outer pins 317, etc. Furthermore, it is possible to capture excess grease, lubricant, etc. between the inner sliding surface 348 and the outer sliding surface 349 by the groove 360.

[0140] Furthermore, in this embodiment shown in FIG. 8, it is possible to achieve the same effects as the above-described embodiments.

[0141] Furthermore, the configuration of this embodiment shown in FIG. 8 can be combined with, for example, the configuration of the fifth embodiment shown in FIG. FIG. 9 is an enlarged cross-sectional view of a casing showing the relationship between the crushed margin and the groove on the inner sliding surface in the reducer of this embodiment. FIG. 10 is a cross-sectional view of a casing showing another example of the relationship between the crushed margin and the groove on the inner sliding surface in the reducer of this embodiment. Specifically, the inner sliding surface 348 may be formed with a plurality of convex portions having an arc-shaped cross section that serve as crushed margins, with grooves formed between them.

[0142] For example, as shown in FIG. 9 , two parallel circumferential protrusions with arc-shaped cross sections can be formed on the casing 322, with a circumferential groove 363 defined between them. Here, protrusion 348a, which is formed as a curved surface at a position on the inner sliding surface 348 that is radially closest to the input shaft 312, and protrusion 348b, which is formed as a curved surface at a position on the inner sliding surface 348 that is radially closest to the outer periphery of the casing, are formed so that their cross-sectional curvatures are approximately the same. Circumferential groove 363 is formed between protrusion 348a and protrusion 348b. This provides a crushed margin on the inner sliding surface 348, improving operational stability and preventing contamination within the reducer 300.

[0143] Alternatively, as shown in FIG. 10, the curvature of the cross section of the protrusion 348a can be made larger than the curvature of the cross section of the protrusion 348b, so that the circumferential groove 363 is positioned on the inner sliding surface 348 closer to the input shaft 312 in the radial direction.

[0144] 8 to 10, grooves 360 are formed on inner sliding surface 348 of casing 322, but grooves can also be formed on outer sliding surface 349. In this case, outer sliding surface 349 is preferably made of metal rather than resin, and inner sliding surface 348 can also be made of resin. That is, as in the second embodiment shown in FIG. 3, a metal ring can be provided on carriers 318, 320, and grooves can be formed on outer sliding surface 349.

[0145] A seventh embodiment of a reducer according to the present invention will be described below with reference to the drawings. Fig. 11 is a cross-sectional view along the axial direction showing the reducer of this embodiment. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. In the figure, reference numeral 400 denotes the reducer.

[0146] The eccentric oscillating type reducer 400 of this embodiment is applied as a reducer to the rotating parts of various machine tools such as the rotating body or arm joint of a robot, a collaborative robot, etc. This reducer 400 is used at a rotation speed of, for example, 80 rpm to 200 rpm.

[0147] In the reducer 400 of this embodiment, as shown in Figures 11 and 12, the input shaft 408 is rotated to rotate the crankshaft (eccentric body) 410, and the external gears 414, 416 are oscillated and rotated in conjunction with the eccentric portions 410a, 410b of the crankshaft 410, thereby obtaining an output rotation that is reduced in speed from the input rotation.

[0148] As shown in Figures 11 and 12, the reducer 400 includes a casing (outer cylinder) 422, a carrier 404, an input shaft 408, multiple (e.g., three) crankshafts 410, a first external gear 414, a second external gear 416, and multiple (e.g., three) transmission gears 420.

[0149] The casing 422 forms the outer surface of the reducer 400 and has a generally cylindrical shape. A large number of pin grooves 422b are formed on the inner peripheral surface of the casing 422. Each pin groove 422b is arranged to extend in the axial direction of the casing 422 and has a semicircular cross-sectional shape in a cross section perpendicular to the axial direction. These pin grooves 422b are arranged at equal intervals in the circumferential direction on the inner peripheral surface of the casing 422.

[0150] The casing 422 has a large number of internally toothed pins (external pins) 417. Each internally toothed pin 417 is attached to a pin groove 422b. Specifically, each internally toothed pin 417 is fitted into a corresponding pin groove 422b and is disposed in a position extending in the axial direction of the casing 422. As a result, the large number of internally toothed pins 417 are lined up at equal intervals along the circumferential direction of the casing 422. The first external teeth 414a of the first external gear 414 and the second external teeth 416a of the second external gear 416 mesh with these internally toothed pins 417. The large number of internally toothed pins 417 form an internal gear 417A.

[0151] Carrier 404 is accommodated in casing 422 while being disposed coaxially with casing 422. Carrier 404 rotates relative to casing 422 about the same axis. Specifically, carrier 404 is disposed radially inside casing 422, and in this state is supported by a pair of main bearings 424, 426 that are spaced apart from each other in the axial direction so as to be rotatable relative to casing 422.

[0152] The carrier 404 includes a base portion having a first carrier (shaft flange) 404a and a plurality of (for example, three) shaft portions 404c, and a second carrier (hold flange) 404b.

[0153] First carrier 404a is disposed near one axial end within casing 422. A circular through-hole 404d is provided in the radial center of first carrier 404a. A plurality of (e.g., three) crankshaft mounting holes 404e (hereinafter simply referred to as mounting holes 404e) are provided around through-hole 404d at equal intervals in the circumferential direction.

[0154] Second carrier 404b is provided axially separated from first carrier 404a and is disposed near the other axial end within casing 422. A through-hole 404f is provided in the radial center of second carrier 404b. A plurality of (e.g., three) crankshaft mounting holes 404g (hereinafter simply referred to as mounting holes 404g) are provided around through-hole 404f at positions corresponding to the plurality of mounting holes 404e of first carrier 404a. A closed space (internal space) is formed within casing 422, surrounded by the inner surfaces of both opposing second carrier 404b and first carrier 404a and the inner circumferential surface of casing 422.

[0155] The three shaft portions 404c are integral with the first carrier 404a and extend linearly from one main surface (inner surface) of the first carrier 404a toward the second carrier 404b. The three shaft portions 404c are arranged at equal intervals in the circumferential direction (see FIG. 12). Each shaft portion 404c is fastened to the second carrier 404b by a bolt 404h (see FIG. 11). This integrates the first carrier 404a, the shaft portions 404c, and the second carrier 404b.

[0156] First carrier (shaft flange) 404a and second carrier (hold flange) 404b are rotatably supported by casing 422 via first main bearing 424 and second main bearing 426. First carrier 404a is rotatably supported by casing 422 via first main bearing 424. Second carrier 404b is rotatably supported by casing 422 via second main bearing 426. The casing 422 is provided with a first metal ring 444 on the first carrier 404a side in the axial direction of the input shaft 408, and a second metal ring 445 on the second carrier 404b side in the axial direction of the input shaft 408. The first metal ring 444 and the second metal ring 445 are fixed integrally with the casing 422.

[0157] The casing 422 has a recess that houses the first metal ring 444. The first metal ring 444 is housed in the recess in the axial direction. In the casing 422, the first metal ring 444 serves as the outer ring of the first main bearing 424. The outer periphery of the first metal ring 444 is connected to the inner periphery of the casing 422.

[0158] A first metal ring 444, which serves as the outer ring of the first main bearing 424, is located on the tip end side in the axial direction of the input shaft 408. The first metal ring 444 forms an inner circumferential sliding surface 448, which serves as the outer ring, on its inner circumferential surface. The inner circumferential sliding surface 448 of the first metal ring 444 contacts the outer circumferential surface of the first carrier 404a. The first metal ring 444 is fixed to the casing 422 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0159] The casing 422 has a recess that accommodates the second metal ring 445. The second metal ring 445 is accommodated in the recess in the axial direction. In the casing 422, the second metal ring 445 serves as an outer ring of the second main bearing 426. The outer periphery of the second metal ring 445 is connected to the inner periphery of the casing 422.

[0160] A second metal ring 445, which serves as the outer ring of the second main bearing 426, is located on the base end side in the axial direction of the input shaft 408. The second metal ring 445 forms an inner circumferential sliding surface 448, which serves as the outer ring, on its inner circumferential surface. The inner circumferential sliding surface 448 of the second metal ring 445 contacts the outer circumferential surface of the second carrier 404b. The second metal ring 445 is fixed to the casing 422 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0161] The main bearings 424, 426 include a first main bearing 424 arranged between the first carrier 404a and the casing 422, and a second main bearing 426 arranged between the second carrier 404b and the casing 422. The main bearings 424, 426 of the present embodiment shown in Figures 11 and 12 are plain bearings. The main bearings 424 and 426 each have an inner sliding surface 448 that serves as an outer ring and an outer sliding surface 449 that serves as an inner ring. Outer circumferential sliding surface 449 is provided on the outer circumferential surfaces of first carrier 404a and second carrier 404b which are integral with the inner ring.

[0162] In the main bearings 424, 426, the sliding surfaces 448, 449 of the first metal ring 444 and the second metal ring 445 are disposed at positions substantially equal to the internal tooth pin 417 in the radial direction. 11 and 12, the first metal ring 444 and the second metal ring 445 are both arranged in contact with the internally toothed pin 417 in a direction along the central axis (main axis) 4La of the input shaft 408. The first metal ring 444, the second metal ring 445, and the internally toothed pin 417 are in contact in the axial direction, thereby making it possible to maintain the strength of the casing 422 over the entire length in the axial direction.

[0163] The input shaft 408 functions as an input section to which the driving force of a drive motor (not shown) is input. The input shaft 408 is inserted into a through-hole 404f of the second carrier 404b and a through-hole 404d of the first carrier 404a. The input shaft 408 is disposed so that its central axis 4La coincides with the axes of the casing 422 and the carrier 404, and rotates about its axis. An input gear 408a is provided on the outer peripheral surface of the tip of the input shaft 408.

[0164] The three crankshafts 410 are disposed at equal intervals around the input shaft 408 within the casing 422 (see FIG. 12). Each crankshaft 410 is rotatably supported by a pair of crankshaft bearings 412a, 412b relative to the carrier 404 (see FIG. 11). Specifically, a first crankshaft bearing 412a is attached to a portion of each crankshaft 410 that is a predetermined length inward from one axial end thereof, and this first crankshaft bearing 412a is fitted into a fitting hole 404e of the first carrier 404a. Meanwhile, a second crankshaft bearing 412b is attached to the other axial end of each crankshaft 410, and this second crankshaft bearing 412b is fitted into a fitting hole 404g of the second carrier 404b. In this way, the crankshafts 410 are rotatably supported by the first carrier 404a and the second carrier 404b.

[0165] Each crankshaft 410 has a shaft body 412c and eccentric portions 410a, 410b formed integrally with the shaft body 412c. The first eccentric portion 410a and the second eccentric portion 410b are arranged side by side in the axial direction between the portions supported by the crank bearings 412a, 412b. The first eccentric portion 410a and the second eccentric portion 410b each have a cylindrical shape and protrude radially outward from the shaft body 412c while being eccentric with respect to the axis of the shaft body 412c. The first eccentric portion 410a and the second eccentric portion 410b are each eccentric from the axis by a predetermined amount and are arranged to have a predetermined phase difference from each other.

[0166] One end of the crankshaft 410, that is, a portion axially outward of the portion that is attached in the attachment hole 404e of the first carrier 404a, is provided with a fitted portion 410c to which a transmission gear 420 is attached.

[0167] The first external gear 414 is disposed in the closed space inside the casing 422 and is attached via a first roller bearing 418a to the first eccentric portion 410a of each crankshaft 410. When each crankshaft 410 rotates and the first eccentric portion 410a rotates eccentrically, the first external gear 414 oscillates and rotates while meshing with the internal pin 417 in conjunction with this eccentric rotation.

[0168] The first external gear 414 has a size slightly smaller than the inner diameter of the casing 422. The first external gear 414 has first external teeth 414a, a central through-hole 414b, a plurality (e.g., three) of first eccentric portion insertion holes 414c, and a plurality (e.g., three) of shaft portion insertion holes 414d. The first external teeth 414a have a smoothly continuous wave shape over the entire circumferential direction of the external gear 414.

[0169] The central through-hole 414b is provided in the radial center of the first external gear 414. The input shaft 408 is inserted and passes through the central through-hole 414b with some play.

[0170] The three first eccentric portion insertion holes 414c are provided at equal intervals in the circumferential direction around the central through-hole 414b in the first external gear 414. The first eccentric portions 410a of the crankshafts 410 are inserted into and pass through the respective first eccentric portion insertion holes 414c with the first roller bearings 418a interposed therebetween.

[0171] The three shaft portion insertion holes 414d are provided at equal intervals in the circumferential direction around the central portion through-hole 414b in the first external gear 414. Each shaft portion insertion hole 414d is disposed at a position between the three first eccentric portion insertion holes 414c in the circumferential direction. The corresponding shaft portion 404c is inserted into and passes through each shaft portion insertion hole 414d with some play.

[0172] The second external gear 416 is disposed in the closed space within the casing 422 and is attached to the second eccentric portion 410b of each crankshaft 410 via a second roller bearing 418b. The first external gear 414 and the second external gear 416 are arranged side by side in the axial direction in accordance with the arrangement of the first eccentric portion 410a and the second eccentric portion 410b. When each crankshaft 410 rotates and the second eccentric portion 410b rotates eccentrically, the second external gear 416 oscillates and rotates while meshing with the internal pin 417 in conjunction with this eccentric rotation.

[0173] The second external gear 416 has a size slightly smaller than the inner diameter of the casing 422 and has a configuration similar to that of the first external gear 414. That is, the second external gear 416 has second external teeth 416a, a central through-hole 416b, multiple (e.g., three) second eccentric portion insertion holes 416c, and multiple (e.g., three) shaft portion insertion holes 416d. These have the same structure as the first external teeth 414a, central through-hole 414b, multiple first eccentric portion insertion holes 414c, and multiple shaft portion insertion holes 414d of the first external gear 414. The second eccentric portion 410b of the crankshaft 410 is inserted into and passes through each second eccentric portion insertion hole 416c with a second roller bearing 418b interposed therebetween.

[0174] Each transmission gear 420 transmits the rotation of the input gear 408a to the corresponding crankshaft 410. Each transmission gear 420 is fitted onto a fitted portion 410c provided at one end of a shaft body 412c of the corresponding crankshaft 410. Each transmission gear 420 rotates integrally with the crankshaft 410 around the same axis as the rotation axis of the crankshaft 410. Each transmission gear 420 has external teeth 420a that mesh with the input gear 408a.

[0175] Here, the materials constituting each part of the reducer 400 of this embodiment shown in FIGS. 11 and 12 will be described.

[0176] In the reducer 400 of this embodiment shown in FIGS. 11 and 12, the carrier 404 and the casing 422 are made of resin, thereby reducing the weight of the reducer 400. Here, inner sliding surface 448, which becomes the outer ring of main bearings 424, 426, is made of a material with higher thermal conductivity than the resin of first carrier 404a and second carrier 404b, which forms outer sliding surface 449, which becomes the inner ring.

[0177] In the main bearings 424, 426, the material constituting the metal rings 444, 445 that form the outer rings may be a metal material, a non-metal material, or the like, as long as it has a higher thermal conductivity than the resin of the carrier 404 that forms the inner ring and is stronger than the resin of the carrier 404. The metal rings 444, 445 of the present embodiment shown in Figures 11 and 12 may be made of a copper-based or aluminum-based metal or alloy, or an iron-based metal such as bearing steel or stainless steel. The internal pin 417 may also be made of the same material as the metal rings 444, 445. Furthermore, the input shaft 408, the crankshaft 410, the first roller bearing 418a, the second roller bearing 418b, the first crank bearing 412a, the second crank bearing 412b, the transmission gear 420, etc. may be made of the same material as the metal rings 444, 445. Furthermore, the first external gear 414 and the second external gear 416 may be made of the same material as the carrier 404.

[0178] In the reducer 400 of this embodiment shown in FIGS. 11 and 12, the main bearings 424, 426 do not include metal components heavier than resin other than the metal rings 444, 445, and therefore further weight reduction can be achieved.

[0179] In the present embodiment shown in Figures 11 and 12, by being configured in this manner, heat transferred from the main bearings 424, 426, which are sliding bearings, to the first metal ring 444 and the second metal ring 445 can be dissipated to the outside, improving heat dissipation performance. By improving the heat dissipation properties of inner circumferential sliding surface 448 and outer circumferential sliding surface 449 in this way, it is possible to prevent malfunctions caused by excessive temperature rises that cause the resin on the surfaces to melt or stick together. Therefore, heat does not build up inside reducer 400, and malfunctions can be prevented.

[0180] At the inner peripheral position of the casing 422, the first metal ring 444, the internally toothed pin 417, and the second metal ring 445, all made of metal, are arranged adjacent to each other in the axial direction and in contact with each other, thereby maintaining strength over the entire axial length of the casing 422. This makes it possible to maintain sufficient strength to prevent malfunction of the reducer 400. In addition, it is possible to prevent the surface pressure on the tooth surfaces of the external gears 414, 416 from increasing, and to prevent the lifespan of the external gears 414, 416 from becoming shorter.

[0181] It should be noted that this embodiment is not limited to the above configuration, and various changes and improvements can be made without departing from the spirit of the present invention. For example, in the present embodiment shown in Figures 11 and 12, two oscillating external gears 414, 416 are provided, but this is not limiting. For example, a configuration in which one oscillating gear is provided, or a configuration in which three or more oscillating gears are provided, may also be used.

[0182] 11 and 12, the input shaft 408 is disposed in the center of the carrier 404, and the plurality of crankshafts 410 are disposed around the input shaft 408. However, the present invention is not limited to this. For example, a center crank type in which the crankshaft 410 is disposed in the center of the carrier 404 may be used. In this case, the input shaft 408 may be disposed in any position as long as the input shaft 408 is disposed so as to mesh with the transmission gear 420 attached to the crankshaft 410.

[0183] 11 and 12, the casing 422 and the carrier 404 are made of resin, and the metal rings 444, 445 are made of metal such as an aluminum alloy. However, the casing 422 and the carrier 404 may also be made of metal. In this case, they may be made of aluminum alloy, but this is not limitative. In particular, as long as the inner circumferential sliding surface 448 and the outer circumferential sliding surface 449 are made of a different material, either resin or metal, that can maintain light weight and necessary rigidity, the materials of the components of the reducer 400 can be selected appropriately.

[0184] In this embodiment shown in FIGS. 11 and 12, it is possible to achieve the same effects as the above-described embodiments.

[0185] An eighth embodiment of a reducer according to the present invention will now be described with reference to the drawings. 13 is a cross-sectional view taken along the main axis of the reducer of this embodiment, in which reference numeral 500 denotes the reducer.

[0186] The reducer 500 of this embodiment is an eccentric oscillating type, and as shown in Figure 13, has an input shaft (eccentric body) 512, an eccentric portion 503, an external gear 514 corresponding to the eccentric portion 503, an eccentric portion bearing 509, a carrier 519, and an internal gear 516.

[0187] As shown in Fig. 13, the input shaft 512 has an opening 512D at its output end in the direction of the central axis (main axis) 5La, and a protrusion 512A at its input end in the direction of the central axis 5La that can be engaged with a motor (not shown). The input shaft 512 is disposed at the radial center of the entire device. The input shaft 512 is formed with a support portion 512B at a position close to the output end in the direction along the central axis 5La. The input shaft 512 is formed with a support portion 512C at a position close to the input end in the direction along the central axis 5La.

[0188] The input shaft 512 is supported on the carrier 519 by a pair of bearings 534 and 536. The bearing 534 supports the input shaft 512 at the position of the support portion 512B. The bearing 536 supports the input shaft 512 at the position of the support portion 512C. The pair of bearings 534, 536 have balls as rolling elements, and there is a gap (play) (not shown) between the rolling elements and the inner and outer rings. An eccentric portion 503 is formed integrally with the input shaft 512, which is sandwiched between bearings 534 and 536 and also functions as an eccentric body shaft. Here, in the direction along the central axis 5La, the direction from the eccentric part 503 toward the bearing 534 is referred to as the output side. In the direction along the central axis 5La, the direction from the eccentric part 503 toward the bearing 536 is referred to as the input side.

[0189] 13, the eccentric portion 503 includes a first eccentric portion 503a, a second eccentric portion 503b, and a third eccentric portion 503c. The first eccentric portion 503a, the second eccentric portion 503b, and the third eccentric portion 503c are arranged in a line in a direction along the central axis 5La. Of the eccentric portions 503a, 503b, and 503c, the first eccentric portion 503a and the third eccentric portion 503c (two outer eccentric portions) are located at both ends in the direction along the central axis 5La. The second eccentric portion (inner eccentric portion) 503b is located inside the first eccentric portion 503a and the third eccentric portion 503c in the direction along the central axis 5La. That is, the first eccentric portion 503a and the third eccentric portion 503c sandwich the second eccentric portion 503b between them in the direction along the central axis 5La.

[0190] The centers of the three eccentric portions 503a, 503b, and 503c are each eccentric by the same amount relative to the central axis 5La of the input shaft 512. The three eccentric portions 503a, 503b, and 503c are arranged at an eccentric phase of 120 degrees, which is obtained by dividing 360 degrees by 3, which is the number of eccentric portions 503a, 503b, and 503c. The maximum eccentric positions of the eccentric portions 503a, 503b, and 503c, where the radial dimension with respect to the central axis 5La is greatest, differ depending on the circumferential position with respect to the central axis 5La.

[0191] Specifically, the maximum eccentric position of the second eccentric portion 503b is shifted by 120 degrees relative to the maximum eccentric position of the first eccentric portion 503a in a clockwise direction (or counterclockwise direction) relative to the center axis 5La of the input shaft 512, and the maximum eccentric position of the third eccentric portion 503c is shifted by a further 120 degrees from the maximum eccentric position of the second eccentric portion 503b. In addition, the maximum eccentric position of the first eccentric portion 503a is shifted by a further 120 degrees from the maximum eccentric position of the third eccentric portion 503c.

[0192] As shown in FIG. 13, the eccentric portion bearing 509 is disposed on the outer periphery of the eccentric portion 503 and is configured to transmit the eccentric rotation of the eccentric portion 503. The eccentric portion bearing 509 has a first eccentric portion bearing 509a, a second eccentric portion bearing 509b, and a third eccentric portion bearing 509c corresponding to each of the eccentric portions 503a, 503b, and 503c. Each of the three eccentric portion bearings 509a, 509b, and 509c has a roller and a retainer that regulates the circumferential position of the roller. None of the three eccentric portion bearings 509a, 509b, and 509c has an inner ring or outer ring. Here, the term "roller" includes the concept of "needle."

[0193] The external gear 514 is mounted on the outer periphery of the eccentric portion 503 via an eccentric portion bearing 509. The external gear 514 oscillates and rotates due to the eccentric portion 503. The external gear 514 has a first external gear 514a, a second external gear 514b, and a third external gear 514c corresponding to each of the eccentric portions 503a, 503b, and 503c.

[0194] Each of the three external gears 514a, 514b, and 514c has a plurality of inner pin holes 515a, 515b, and 515c. The plurality of inner pin holes 515a, 515b, and 515c pass through each of the external gears 514a, 514b, and 514c. An inner pin 540 with a rotatable inner roller 537 is fitted with play in each of the external gears 514a, 514b, and 514c.

[0195] The carrier 519 includes a first carrier (shaft flange) 518 and a second carrier (hold flange) 520. The first carrier 518 is formed integrally with an inner pin 540. The first carrier 518 and the second carrier 520 are connected and fixed together by a bolt 540a. The bolt 540a is screwed into the second carrier 520 from the outside and connected to and fixed to the inner pin 540.

[0196] The first carrier 518 is disposed at a position closer to the output side than the first external gear 514a, and the second carrier 520 is disposed at a position closer to the input side than the third external gear 514c. Carrier 519 is supported on casing 522 by main bearings 524 and 526. First carrier 518 is supported on casing 522 by first main bearing 524. Second carrier 520 is supported on casing 522 by second main bearing 526.

[0197] The main bearings 524 and 526 are both sliding bearings having sliding surfaces 548 and 549. The main bearings 524 and 526 have metal rings 544 and 545, respectively. The main bearing 524 has a first metal ring 544. The second main bearing 526 has a second metal ring 545. The first metal ring 544 is provided on the output side of the casing 522. The second metal ring 545 is provided on the input side of the casing 522. The first metal ring 544 and the second metal ring 545 are fixed to the casing 522 as a single unit.

[0198] The outer periphery of the first metal ring 544 is fixed to the inner periphery of the casing 522. A recess that accommodates the first metal ring 544 is provided in the inner periphery of the casing 522. The first metal ring 544 is accommodated in the recess in the axial direction. The first metal ring 544 serves as the outer ring of the first main bearing 524.

[0199] A first metal ring 544, which serves as the outer ring of the first main bearing 524, is located on the output side of the casing 522. The first metal ring 544 has an inner periphery that forms an inner sliding surface 548 that serves as the outer ring. The inner sliding surface 548 of the first metal ring 544 is in contact with the first carrier (shaft flange) 518. The first metal ring 544 is fixed to the casing 522 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0200] The outer periphery of the second metal ring 545 is fixed to the inner periphery of the casing 522. A recess that accommodates the second metal ring 545 is provided in the inner periphery of the casing 522. The second metal ring 545 protrudes further from the recess toward the input side in the direction along the central axis 5La. In the casing 522, the second metal ring 545 serves as an outer ring of the second main bearing 526.

[0201] A second metal ring 545, which serves as the outer ring of the second main bearing 526, is located on the input side of the casing 522. The second metal ring 545 is exposed on the input side of the casing 522. The inner periphery of the second metal ring 545 forms an inner circumferential sliding surface 548, which serves as the outer ring. The inner circumferential sliding surface 548 of the second metal ring 545 contacts the second carrier (hold flange) 520. The second metal ring 545 is fixed to the casing 522 by a fit such as a clearance fit, an interference fit, or an intermediate fit. The fit gap may be set to correspond to the difference in thermal expansion coefficients.

[0202] The main bearings 524 , 526 include a first main bearing 524 disposed between the first carrier 518 and the casing 522 , and a second main bearing 526 disposed between the second carrier 520 and the casing 522 . The main bearings 524 and 526 are in contact with an inner circumferential sliding surface 548 that serves as an outer ring, and are provided with an outer circumferential sliding surface 549 that serves as an inner ring. Outer peripheral sliding surface 549 is provided on the outer peripheral surfaces of carriers 518 and 520 which are integrated with the inner rings. Outer peripheral sliding surface 549 moves while maintaining a rubbing state with inner peripheral sliding surface 548 which is the outer ring provided on the inner peripheral surfaces of metal rings 544 and 545.

[0203] The main bearings 524, 526 have an outer peripheral sliding surface 549 of the inner ring integrated with the first and second carriers 518, 520, respectively, and an inner peripheral sliding surface 548 of the outer ring supported on the inner circumference of the casing 522 as separate metal rings 544, 545.

[0204] In the main bearings 524, 526, the sliding surfaces 548, 549 formed on the first metal ring 544 and the second metal ring 545 are disposed at positions substantially equal to the outer pin (internal tooth pin) 517 in the radial direction. 13, the first metal ring 544 and the second metal ring 545 are arranged so as to contact the internally toothed pin 517 in the direction along the central axis 5La of the input shaft 512. By arranging the first metal ring 544, the second metal ring 545, and the internally toothed pin 517 so as to contact each other in the direction along the central axis 5La, it is possible to maintain the strength of the casing 522 over the entire length in the direction along the central axis 5La.

[0205] The inner sliding surface 548 that forms the outer ring of the main bearings 524 and 526 is made of a material with a higher thermal conductivity than the resin of the carriers 518 and 520 that forms the outer sliding surface 149 that forms the inner ring.

[0206] In the main bearings 524, 526, the material constituting the metal rings 544, 545 that serve as the outer rings may be a metal material, a non-metal material, or the like, as long as it has a higher thermal conductivity than the resin of the carriers 518, 520 that serve as the inner rings and is stronger than the resin of the carriers 518, 520. The metal rings 544, 545 of the present embodiment shown in Fig. 13 may be made of a copper-based or aluminum-based metal, or an iron-based metal such as bearing steel.

[0207] The internal gear 516 has an internal gear body 516a in which a cylindrical internal pin 517 and a pin groove 516b that rotatably supports the internal pin 517 are formed. The internal gear body 516a is integral with a casing 522. There is a slight difference in the number of teeth between the internal gear 516 and the first external gear 514a. There is a slight difference in the number of teeth between the internal gear 516 and the second external gear 514b. There is a slight difference in the number of teeth between the internal gear 516 and the third external gear 514c. An oil seal 533 is disposed between the casing 522 and the first carrier 518, at an outer position of a metal ring 544.

[0208] When the input shaft 512 rotates due to the drive of a motor (not shown), the eccentric portion 503 provided on the outer periphery of the input shaft 512 rotates eccentrically integrally with the input shaft 512. Due to the rotation of the eccentric portion 503, the external gears 514a, 514b, and 514c corresponding to the eccentric portions 503a, 503b, and 503c, respectively, also attempt to oscillate and rotate around the input shaft 512. However, because their rotation is restricted by the internal gear 516, the external gears 514a, 514b, and 514c move almost exclusively in an oscillating motion while in contact with the internal gear 516.

[0209] At this time, the oscillation component is absorbed by the inner pin holes 515a, 515b, 515c and the inner pin 540 (and the inner roller 537). As a result, the first external gear 514a, the second external gear 514b, and the third external gear 514c rotate relative to the internal gear 516, which is in a fixed state, by an amount corresponding to the difference in the number of teeth between the internal gear 516 and the first external gear 514a, the second external gear 514b, and the third external gear 514c. In other words, only the rotation component resulting from the difference in the number of teeth between the internal gear 516 and the first external gear 514a, the second external gear 514b, and the third external gear 514c is transmitted to the carrier 519.

[0210] Here, the materials constituting each part of the reducer 500 of this embodiment shown in FIG. 13 will be described.

[0211] In the reducer 500 of this embodiment shown in Figure 13, the carrier 519, casing 522, first external gear 514a, second external gear 514b, and third external gear 514c are made of resin, making the reducer 500 lightweight. Here, inner sliding surface 548, which becomes the outer ring of main bearings 524, 526, may be made of a material with higher thermal conductivity than the resin of first carrier 518 and second carrier 520, which form outer sliding surface 549, which becomes the inner ring.

[0212] In the main bearings 524, 526, the material constituting the metal rings 544, 545 that form the outer rings may be a metal material, a non-metal material, or the like, as long as it has a higher thermal conductivity than the resin of the carrier 519 that forms the inner ring and is stronger than the resin of the carrier 519. The metal rings 544, 545 of the present embodiment shown in Fig. 13 may be made of a copper-based or aluminum-based metal or alloy, or an iron-based metal such as bearing steel or stainless steel. The internal tooth pin 517 may also be made of the same material as the metal rings 544 and 545. The input shaft 512, the eccentric bearing 509, the bearings 534 and 536, etc. may also be made of the same material as the metal rings 544 and 545.

[0213] In the reducer 500 of this embodiment shown in FIG. 13, the main bearings 524, 526 do not include metal components heavier than resin other than the metal rings 544, 545, and therefore further weight reduction can be achieved.

[0214] In the present embodiment shown in FIG. 13, by being configured in this manner, heat transferred from the main bearings 524, 526, which are sliding bearings, to the first metal ring 544 and the second metal ring 545 can be dissipated to the outside, improving heat dissipation performance. By improving the heat dissipation properties of inner circumferential sliding surface 548 and outer circumferential sliding surface 549 in this way, it is possible to prevent malfunctions caused by excessive temperature rises that cause the resin on the surfaces to melt or stick together. Therefore, heat does not build up inside reducer 500, and malfunctions can be prevented.

[0215] At the inner peripheral position of the casing 522, the first metal ring 544, the internal tooth pin 517, and the second metal ring 545, which are made of metal, are arranged adjacent to each other in the axial direction and in contact with each other, thereby making it possible to maintain strength over the entire axial length of the casing 522. As a result, it is possible to maintain sufficient strength to prevent malfunction of the reducer 500.

[0216] In the embodiment shown in Fig. 13, the first carrier 518 functions as an output shaft for a mating machine (not shown). In the embodiment shown in Fig. 13, the carrier 519 is provided with the second carrier 520 and has the inner pin 540 supported on both sides, but the carrier may have the inner pin supported on one side. Furthermore, the present invention is not limited to a configuration in which three or more eccentric bodies are arranged with an eccentric phase of 360 degrees / (number of eccentric bodies), and the axial length of the inner eccentric body located inside the outer eccentric body is longer than the axial length of the two outer eccentric bodies located at both ends of the axial direction among the three or more eccentric bodies.

[0217] In this embodiment shown in FIG. 13, it is possible to achieve the same effects as the above-described embodiments.

[0218] A ninth embodiment of a reducer according to the present invention will now be described with reference to the drawings. Fig. 14 is a cross-sectional view taken along the main axis direction of the reducer of this embodiment. Fig. 15 is a cross-sectional view taken along the line XV-XV in Fig. 14. In the figure, reference numeral 600 denotes the reducer.

[0219] The reducer 600 of this embodiment is an eccentric oscillating reducer that causes rotation of one of the internal gear and the external gear by oscillating the external gear that meshes with the internal gear, and outputs the rotation component that has occurred from the output member to the driven device.

[0220] As shown in Figures 14 and 15, the reducer 600 of this embodiment includes an input shaft 612, an external gear 614, an internal gear 616, carriers 618, 620, a casing 622, main bearings 624, 126, an inner pin 140, and a carrier pin 138. Hereinafter, the direction along the central axis (main axis) 6La of the internal gear 616 will be referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the central axis 6La will be referred to as the "circumferential direction" and the "radial direction," respectively. Also, hereinafter, for convenience, one side of the axial direction (the right side in FIG. 14) will be referred to as the input side, and the other side (the left side in FIG. 14) will be referred to as the anti-input side or output side.

[0221] The input shaft 612 is rotated about its rotational center line by rotational power input from a drive source. The reducer 600 of this embodiment shown in Figures 14 and 15 is a center crank type in which the rotational center line of the input shaft 612 is coaxial with the central axis line 6La of the internal gear 616. The drive source is, for example, a motor, a gear motor, an engine, etc.

[0222] The input shaft 612 is an eccentric shaft having a plurality of eccentric portions 612a for oscillating the external gear 614. An input shaft (eccentric body) 612 configured in this manner is sometimes called a crankshaft. The axis of the eccentric portions 612a is eccentric with respect to the rotation center line of the input shaft 612. In the present embodiment shown in FIGS. 14 and 15, two eccentric portions 612a are provided, and the eccentric phases of adjacent eccentric portions 612a are shifted by 180°.

[0223] Input shaft 612 has its input side supported by second carrier 620 via input shaft bearing 634, and its non-input side supported by first carrier 618 via input shaft bearing 634. Input shaft 612 is supported so as to be freely rotatable with respect to first carrier 618 and second carrier 620. There are no particular limitations on the configuration of input shaft bearing 634, but in this example it is a ball bearing with spherical rolling elements.

[0224] The internal gear 616 meshes with the external gear 614. The internal gear 616 of this embodiment shown in Figures 14 and 15 has an internal gear main body 616a integrated with a casing 622, and outer pins (internal pins) 617 arranged in pin grooves 616b formed at intervals in the circumferential direction on the internal gear main body 616a. The outer pins 617 are cylindrical or columnar pin members rotatably supported on the internal gear main body 616a. The outer pins 617 have the same diameter over their entire axial length. The outer pins 617 form the internal teeth of the internal gear 616. The number of outer pins 617 (the number of internal teeth) of the internal gear 616 is slightly more (by one in this example) than the number of external teeth of the external gear 614.

[0225] The casing 622 integrated with the internal gear main body 616a is made of resin. Various resins can be used for the internal gear main body 616a, but in this example, the casing 622 integrated with the internal gear main body 616a is made of POM (polyacetal). The internal gear main body 616a may also be made of a resin other than POM, such as PEEK (polyetheretherketone).

[0226] The resin used for the casing 622 integrated with the internal gear main body 616a and the other components of this embodiment may be a resin containing reinforcing fibers such as glass fiber or carbon fiber, a resin containing no reinforcing fibers, or a resin impregnated into a base material such as paper or cloth and laminated therewith. The resin used for each component of this embodiment may be a resin blended with a thermally conductive filler.

[0227] In the reducer 600, the outer pins 617 may be made of a material having a higher thermal conductivity [W / (m·K)] than the resin of the internal gear body 616a.

[0228] The material constituting the outer pins 617 may be any material that has higher thermal conductivity and rigidity than the resin of the internal gear body 616a, and may be a metal material, a highly thermally conductive resin, a non-metallic material, etc. The outer pins 617 may be a resin containing carbon nanotubes (CNTs) or boron nitride nanotubes (BNNTs). The outer pins 617 of the present embodiment shown in Figures 14 and 15 may be made of an iron-based metal such as bearing steel.

[0229] The outer pin 617 may be a solid member or a hollow member. The outer pin 617 may be a member with a multilayer structure in which a core material is wrapped with a surface material. For example, one of the core material and the surface material of the outer pin 617 may be an iron-based metal, and the other may be a copper-based or aluminum-based metal. In this case, it is possible to achieve both mechanical properties and thermal properties. As another example, one of the core material and the surface material of the outer pin 617 may be made of metal, and the other may be made of resin. The outer pin 617 may also be made of sintered metal, ceramic, or the like.

[0230] The external gears 614 are individually provided corresponding to the multiple eccentric portions 612a. The external gears 614 are rotatably supported by the corresponding eccentric portions 612a via eccentric bearings 630. As shown in FIG. 15, the external gears 614 are formed with multiple carrier pin holes (inner pin holes) 639 that pass through the external gears 614 and are equally spaced in the circumferential direction at positions offset from the axis of the external gears 614. Carrier pins (inner pins) 638 are inserted into the carrier pin holes 139. All of these multiple carrier pin holes 639 have the same diameter. The diameter of the carrier pin holes 639 is set larger than the diameter of the carrier pins 638.

[0231] The external gear 614 is made of resin, just like the internal gear main body 616a. Various resins can be used for the external gear 614. The external gear 614 is disposed closer to the input shaft 612 than the internal gear main body 616a. The external gear 614 may be made of PEEK. The external gear 614 may be made of a resin other than PEEK, such as POM.

[0232] The multiple carrier pin holes 639 are circular through-holes provided at the same radial position. Wave-shaped teeth are formed on the outer periphery of the external gear 614, and these teeth move while making contact with the internal gear 616, allowing the external gear 614 to oscillate within a plane normal to the central axis 6La. A carrier pin 638 passes through the carrier pin hole 639. A gap is provided between the carrier pin 638 and the carrier pin hole 639 to provide play for absorbing the oscillating component of the external gear 114. The carrier pin 638 and the inner wall surface of the carrier pin hole 639 come into partial contact.

[0233] The carriers 618, 620 are arranged on both axial sides of the external gear 614. The carriers 618, 620 include a first carrier (shaft flange) 618 arranged on the side of the external gear 614 opposite the input side, and a second carrier (hold flange) 620 arranged on the side of the external gear 614 on the input side. First carrier 618 and second carrier 620 are rotatably supported by casing 122 via first main bearing 624 and second main bearing 626. First carrier (shaft flange) 618 is rotatably supported by casing 622 via first main bearing 624. Second carrier (hold flange) 620 is rotatably supported by casing 622 via second main bearing 626.

[0234] The carriers 618 and 620 are generally disk-shaped. The first carrier 618 rotatably supports the input shaft 612 via an input shaft bearing 634. The second carrier 620 rotatably supports the input shaft 612 via an input shaft bearing 634. The carrier pin (inner pin) 638 is connected to the first carrier (shaft flange) 618 and the second carrier (hold flange) 620 by a bolt 638a made of a rigid material such as an iron-based metal.

[0235] The first carrier 618 and the second carrier 620 are connected via a plurality of carrier pins 638. The carrier pins 638 axially penetrate the plurality of external gears 614 at positions radially offset from the axis of the external gears 614. In this example, the carrier pins 638 are provided separately from the carriers 618, 620, but some of these pins may be formed integrally as part of the carriers 618, 620.

[0236] One of first carrier 618 and casing 622 functions as an output member that outputs rotational power to a driven device, and the other functions as a fixed member that is fixed to an external member that supports reducer 600. The output member is rotatably supported by the fixed member via main bearings 624, 626. A driven member that is rotationally driven by reducer 600 may be connected by bolts or the like to the end face on the opposite input side of first carrier 618. Alternatively, a driven member that is rotationally driven by reducer 600 may be connected by bolts or the like to an outer peripheral flange of casing 622.

[0237] The casing 622 has a hollow cylindrical shape as a whole, and the internal gear 616 is provided on its inner periphery. A flange or the like may be provided on the outer periphery of the casing 622. In the casing 622, pin grooves 616b that support the outer pins 617 are formed to both ends in the direction of the central axis 6La. The outer pins 617 extend outward beyond the pin grooves 616b in the direction of the central axis 6La. In other words, the length of the outer pins 617 in the direction of the central axis 6La is set to be greater than the length of the pin grooves 616b in the direction of the central axis 6La. The outer pins 617 protrude outward from the pin grooves 616b in the direction of the central axis 6La.

[0238] The carriers 618, 620 are provided with circumferential recesses 646, 647 that accommodate the outer pins 617 protruding from the pin grooves 616b. The circumferential recesses 646, 647 are formed over the entire circumferential length of the carriers 618, 6202. The circumferential recesses 646, 647 have a uniform cross-sectional shape over the entire circumferential length. The radial cross section of the peripheral recesses 646, 647 is rectangular. The radial cross section of the peripheral recesses 646, 647 corresponds to the axial cross section of the outer pin 617. Each of the circumferential recesses 646, 647 has an annular surface 649a that is a flat surface along the radial direction, and an outer circumferential surface 649b that is a cylindrical surface that continues to the annular surface 649a at a position close to the central axis 6La.

[0239] The outer pin 617 protruding from the pin groove 616b is movable in the circumferential direction inside the circumferential recesses 646,647 in accordance with the relative rotation of the carriers 618,620 and the casing 622 about the central axis 6La. Circumferential recesses 646,647 in the carriers 618,620 form the inner rings of the main bearings 624,626.

[0240] Each of the main bearings 624, 626 has an outer pin 617 and a pin groove 616b that serves as a retainer that regulates the circumferential position of the outer pin 617. The internal gear body 616a of the main bearings 624, 626 corresponds to the outer ring. In other words, the main bearings 624, 626 of this embodiment shown in Figures 14 and 15 are rolling bearings that use the outer pin 617. The main bearings 624 , 626 include a first main bearing 624 disposed between the first carrier 618 and the casing 622 , and a second main bearing 626 disposed between the second carrier 620 and the casing 622 .

[0241] The first main bearing 624 is composed of a pin groove 616b of the casing 622, an outer pin 617, and a circumferential recess 646 provided on the outer periphery of the first carrier 618 on the input side. In the circumferential recess 646, an end face 617b of the outer pin 617 is slightly spaced from or occasionally comes into contact with an annular surface 649a that extends along the radial direction. In the circumferential recess 646, a circumferential surface 617c of the outer pin 617 comes into contact with an outer peripheral surface 649b that is closer to the output side than the annular surface 649a.

[0242] An output-side end face 617b of the outer pin 617 moves without contacting or in sliding contact with the annular surface 649a in accordance with the relative rotation about the central axis 6La between the first carrier 618 and the casing 622. A peripheral surface 617c near the end face 617b of the outer pin 617 moves in rolling contact with the outer peripheral surface 649b in accordance with the relative rotation about the central axis 6La between the first carrier 618 and the casing 622. The peripheral surface 617c of the outer pin 617 maintains a state of linear contact with the outer peripheral surface 649b in the direction of the central axis 6La.

[0243] The second main bearing 626 is composed of a pin groove 616b of the casing 622, an outer pin 617, and a circumferential recess 647 provided on the outer periphery of the second carrier 620 on the output side. In the circumferential recess 647, an end face 617b of the outer pin 617 is slightly spaced from or occasionally comes into contact with an annular surface 649a that extends along the radial direction. In the circumferential recess 647, a circumferential surface 617c of the outer pin 617 comes into contact with an outer circumferential surface 649b that is closer to the input side than the annular surface 649a.

[0244] An input-side end face 617b of the outer pin 617 moves without contacting or in sliding contact with the annular surface 649a in accordance with the relative rotation about the central axis 6La between the second carrier 620 and the casing 622. A peripheral surface 617c near the end face 617b of the outer pin 617 moves in rolling contact with the outer peripheral surface 649b in accordance with the relative rotation about the central axis 6La between the second carrier 620 and the casing 622. The peripheral surface 617c of the outer pin 617 maintains a state of linear contact with the outer peripheral surface 649b in the direction of the central axis 6La.

[0245] In the main bearings 624, 626, the contact length in the direction of the central axis 6La between the peripheral surface 617c and the outer peripheral surface 649b is equal for all of the multiple outer pins 617. Furthermore, in the main bearings 624, 626, the contact positions between the peripheral surface 617c and the outer peripheral surface 649b are spaced apart by an equal circumferential distance for all of the multiple outer pins 617. This circumferential distance for the multiple outer pins 617 is maintained by the circumferential separation distance of the pin grooves 616b.

[0246] In the main bearings 624, 626, a radially outward force is applied from the circumferential recesses 646, 647 to both ends of the outer pin 617 in the direction along the central axis 6La. Also, a radially inward force is applied from the pin groove 616b to the center of the outer pin 617 in the direction along the central axis 6La. As a result, the main bearings 624, 626 support the casing 622 and the carriers 618, 620 so that they can rotate relative to each other all around.

[0247] In the circumferential recess 646 of the first carrier 618 and the circumferential recess 647 of the second carrier 620, the distance between the annular surface 649a of the circumferential recess 646 and the annular surface 649a of the circumferential recess 647 in the direction along the central axis 6La is set to be slightly larger than or approximately equal to the axial dimension of the outer pin 617. The diameter of the outer peripheral surface 649b of the peripheral recesses 646, 647 from the central axis 6La is set to a value obtained by subtracting the diameter of the outer pin 617 from the maximum diameter of the pin groove 616b.

[0248] The radial dimension of the annular surface 649a can be set equal to the radial dimension of the outer pin 617. In this case, the outer peripheral surfaces of the carriers 618, 620 have the same radial dimension as the cylindrical surface connecting the radially outermost positions of the outer pin 617. At the same time, the entire end surface 617b of the outer pin 617 can come into contact with the annular surface 649a. Alternatively, the radial dimension of the annular surface 649a can be set to be smaller than the radial dimension of the outer pin 617. In this case, the cylindrical surface connecting the radially outermost positions of the outer pin 617 has a larger radial dimension than the outer peripheral surfaces of the carriers 618, 620. The axial length of the outer peripheral surface 649b and the axial length of the peripheral surface 617c of the outer pin 617 that contacts the outer peripheral surface 649b are set to be approximately equal values.

[0249] In the main bearings 624, 626, the outer pin 617 is made of a heat conductive material that is more wear-resistant than the resin of the casing 622 that forms the pin groove 616b, which becomes the inner surface 648 of the outer ring, and the carriers 118, 120 that form the outer surface 649b, which becomes the inner ring. Specifically, the material constituting the outer pin 617 may be a metal material, a non-metal material, or the like, as long as it has a higher thermal conductivity than the resin of the casing 622 that forms the outer ring and the resin of the carriers 618, 120 that form the inner ring, and is stronger than the resin of the carriers 618, 620. The outer pin 617 of the present embodiment shown in Figures 14 and 15 may be made of a copper-based or aluminum-based metal or alloy, or an iron-based metal such as bearing steel.

[0250] In the main bearings 624, 626, the outer pin 617 is sandwiched between a pin groove 616b that forms an inner peripheral surface 648 of the outer ring and an outer peripheral surface 649b of the peripheral recesses 646, 647 that form the inner ring. That is, the outer pin 617 is sandwiched between the casing 622 and the carriers 118 and 120 .

[0251] The outer pins 617 that protrude in the direction along the central axis 6La from the pin grooves 616b that form the main bearings 624, 626 also serve as the outer pins 617 that form the internal gear 616. Therefore, the main bearing 624, the internal gear 616, and the main bearing 626 are arranged adjacent to each other along the central axis 6La. This makes it possible to maintain the strength of the reducer 600 over the entire length in the axial direction.

[0252] The carrier pin (inner pin) 638 is inserted with a gap into and passes through a carrier pin hole (inner pin hole) 639 formed through the external gear 614. One end of the carrier pin 638 is fitted into a recess 618c of the first carrier 618, and the other end is fitted into a recess 620c of the second carrier 620. The carrier pin 638 is fixed to the recesses 618c, 620c with a bolt 638a. The carrier pin 638 may be press-fitted into the recesses 618c, 620c, in which case it is not fixed by a bolt or the like.

[0253] The carrier pins (inner pins) 638 abut against and are in contact with parts of carrier pin holes 639 formed in the external gear 614, restricting the rotation of the external gear 614 and allowing only its oscillation. The carrier pins 638 function as connecting members that contribute to the transmission of power between the first carrier 618 and the second carrier 620 and the external gear 614. Furthermore, carrier pins 638 that do not contact the carrier pin holes 639 of the external gear 614 may be provided, and in this case the carrier pins 638 do not contribute to restricting the rotation of the external gear 614. This carrier pin 638 functions as a connecting member that contributes only to the connection between the first carrier 618 and the second carrier 620.

[0254] The use of reducers is expanding to collaborative robots that operate close to humans. To expand their applications, it is desirable to reduce the weight and noise of reducers. Conventional reducers are made up of components made of iron-based metals. To reduce weight, it is possible to form the components from low-density materials. Resin is a suitable material for this purpose. However, using resin for the components can lead to problems such as breakdowns due to reduced strength and rigidity. Furthermore, resin can lead to increased temperature due to reduced heat dissipation, shortening the component's lifespan. For this reason, it is desirable to select the materials for each component while taking into consideration maintaining strength, reducing weight, and dissipating heat. In particular, it is necessary to avoid a decrease in strength that accompanies weight reduction.

[0255] The reducer 600 can be made lighter by constructing many of its components from resin. The casing 622, carriers 618, 620, and external gear 614 account for a large portion of the volume of the components of the reducer 600, so by constructing these components from resin, a significant weight reduction can be achieved. At the same time, in consideration of strength and heat dissipation, it is preferable that the input shaft 612, carrier pin (inner pin) 638 and bolt 638a, eccentric bearing 630, input shaft bearing 634, and outer pin 617 be constructed from metal.

[0256] Furthermore, in the reducer 600, the outer pin 617 is used as the main bearings 624, 626 to rotatably support the casing 622 and the carriers 618, 620 without providing separate bearings, thereby achieving further weight reduction. Also, the main bearings 624, 626 do not include any metal components other than the outer pin 617, thereby achieving further weight reduction.

[0257] At the same time, in the main bearings 624, 626, the peripheral surface 617c of the outer pin 617 moves in rolling contact with the outer peripheral surface 649b in accordance with the relative rotation about the central axis 6La of the carriers 618, 620 and the casing 622, so that friction can be reduced and operational stability can be improved compared to a configuration in which sliding contact occurs. Also, because the annular surface 649a and the outer peripheral surface 649b are made of resin and the outer pin 617 is made of metal, heat generated at the points where these come into contact with each other can be efficiently released, improving heat dissipation.

[0258] In the reducer 600, a large amount of heat is often generated inside, particularly around the main bearings 624, 626. Also, a large amount of heat is often generated around the input shaft 612, which rotates at a relatively high speed. Furthermore, if the carrier pin (inner pin) 638 and the external gear 614 do not maintain sufficient strength, malfunction of the reducer 600 may occur. In this way, if the heat generated inside the reducer is not dissipated to the outside, the temperature rise of the reducer will be rapid. As the temperature of resin components increases, their rigidity and strength decrease rapidly, and if they continue to be used in this state, there is a high possibility that they will break.

[0259] For this reason, when one of the components that move relative to each other is made of a resin material, it is desirable to make the other out of a material that has higher wear resistance and thermal conductivity [W / (m·K)] than the resin material. In this case, the heat generated inside can be dissipated to the outside better than if the other component had a low thermal conductivity. At the same time, the component's lifespan can be extended compared to when the component has low wear resistance. Furthermore, noise can also be reduced.

[0260] The material constituting the outer pin 617 that becomes the main bearings 624, 626 may be a material that has higher wear resistance and higher thermal conductivity than the resin constituting the annular surface 649a and outer peripheral surface 649b of the inner ring, and may be a metallic material, a non-metallic material, or a highly rigid and highly thermally conductive material. 14 and 15, the outer pin 617 constituting the main bearings 624, 626 of the present embodiment may be made of an iron-based metal such as bearing steel, an aluminum-based metal, or a light metal such as aluminum, magnesium, beryllium, or titanium, or a composite material of these. Alternatively, the outer pin 617 may be made of ceramics or the like. By forming the other components such as the carriers 618, 620 and the casing 622 from resin, it is possible to achieve both a reduction in weight and mechanical strength of the reducer 600.

[0261] High-speed rotation before deceleration is input to the input shaft 612 and the eccentric bearing 630 and input shaft bearing 634 arranged in contact with the input shaft 612. Therefore, their temperature rise is relatively large, and if their heat resistance is low, the allowable input rotation speed will be low. For this reason, the input shaft 612, the input shaft bearing 634, and the eccentric bearing 630 may be made of a metal such as an iron-based metal. In this case, the decrease in the allowable input rotation speed can be suppressed. Because the input shaft 612 is subjected to large torsional stress, it is desirable for the input shaft 612 to be made of a material with higher rigidity than the carriers 618 and 620. The input shaft 612 may be made of an iron-based metal, which has higher torsional strength than aluminum. The iron-based metal may be carbon steel, bearing steel, stainless steel, or the like, depending on the desired characteristics.

[0262] To ensure the transmission of rotation to the external gear 614, it is desirable that the rigidity of the carrier pin (inner pin) 638 be high. Also, to ensure the connection strength between the first carrier 618 and the second carrier 620, it is desirable that the rigidity of the carrier pin 638 be high. From these perspectives, the carrier pin 638 and the bolt 638a may be made of metal. In this example, the carrier pin 638 can be made of an iron-based metal.

[0263] The operation of the reducer 600 configured as above will be described. When rotational power is transmitted from the drive device to the input shaft 612, the eccentric portion 612a of the input shaft 612 rotates around a central axis 6La that serves as the center of rotation passing through the input shaft 612, and the eccentric portion 612a causes the external gear 614 to oscillate. At this time, the external gear 614 oscillates so that its own axis rotates around the rotation center line of the input shaft 612. As the external gear 614 oscillates, the meshing positions of the external gear 614 and the outer pins 617 of the internal gear 616 are sequentially shifted. As a result, with each rotation of the input shaft 612, rotation of one of the external gear 614 and the internal gear 616 occurs by an amount corresponding to the difference between the number of teeth of the external gear 614 and the number of outer pins 617 of the internal gear 616. In the present embodiment shown in FIGS. 14 and 15 , the rotation of the external gear 614 causes reduced rotation to be output from the first carrier 618 or the casing 622.

[0264] At this time, in the main bearings 624, 626, the outer pin 617 protruding from the pin groove 616b moves while rolling relative to the circumferential recesses 646, 647 in accordance with the relative rotation about the central axis 6La between the carriers 618, 620 and the casing 622. The circumferential surface 617c of the outer pin 617 is in linear contact with the outer circumferential surface 649b in the direction of the central axis 6La.

[0265] In the reducer 600 of this embodiment shown in Figures 14 and 15, the outer pins 617 serve both as internal pins that form the internal teeth of the internal gear 616 and as rollers for the main bearings 624, 626. This allows for a reduction in the number of components, making it possible to reduce the size and weight of the reducer 600. In particular, since there is no need to provide main bearings as separate members outside the outer pins 617, the thickness dimension of the reducer 600 can be reduced. Furthermore, since the outer pins 617 are arranged so as to cover most of the thickness near the outer periphery of the reducer 600, the reducer 600 can have sufficient strength against malfunctions and the like caused by deformation.

[0266] 14 and 15 , the reducer 600 of this embodiment does not include any metal component heavier than resin other than the outer pin 617 as the main bearings 624, 626, thereby achieving further weight reduction. Furthermore, when one component is made of a resin component, the other component can be made of a material that has higher wear resistance and thermal conductivity than the resin component, thereby achieving weight reduction, higher rigidity, higher heat dissipation, and improved operational reliability.

[0267] In the present embodiment shown in FIGS. 14 and 15, it is possible to achieve the same effects as the above-described embodiments.

[0268] A tenth embodiment of a reducer according to the present invention will now be described with reference to the drawings. Fig. 16 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the ninth embodiment shown in Figs. 14 and 15 above in terms of the outer pins. Other components corresponding to those of the ninth embodiment shown in Figs. 14 and 15 above are designated by the same reference numerals, and description thereof will be omitted.

[0269] In the reducer 600 of this embodiment, as shown in Fig. 16, the outer pin 617 of the main bearings 624, 626 is formed with expanded diameter portions (bushings) 617f at both ends. The expanded diameter portions 617f are formed in the portion protruding from the pin groove 616b. The portion of the outer pin 617 housed in the pin groove 616b has the same configuration as that of the ninth embodiment shown in Figs. 14 and 15 described above. The diameter of the expanded diameter portion 617f is larger than the diameter of the portion of the outer pin 617 housed in the pin groove 616b. The diameter of the expanded diameter portion 617f is constant over the entire length of the expanded diameter portion 617f in the direction along the central axis 6La. Furthermore, the expanded diameter portions 617f formed on both ends of the outer pin 617 have the same shape.

[0270] The end face 617b of the outer pin 617 with the expanded diameter portion 617f is at the same axial position as when no expanded diameter portion is formed, and is slightly spaced apart from or occasionally comes into contact with the annular surface 649a. The peripheral surface 617c of the expanded diameter portion 617f contacts the outer peripheral surface 649b. Accordingly, the radial positions of the peripheral recesses 646, 647 also become closer to the central axis 6La. Similarly, the radial dimension of the annular surface 649a also becomes larger.

[0271] The peripheral recess 646 is larger in the radial direction than the ninth embodiment shown in FIGS. 14 and 15 in accordance with the cross-sectional shape of the expanded diameter portion 617f. The peripheral surface 617c of the expanded diameter portion 617f moves in rolling contact with the outer peripheral surface 649b in accordance with the relative rotation about the central axis 6La between the carriers 618, 620 and the casing 622. The peripheral surface 617c of the outer pin 617 maintains a state of linear contact with the outer peripheral surface 649b in the direction of the central axis 6La.

[0272] In the reducer 600 of this embodiment shown in Fig. 16, the diameter of the circumferential surface 617c of the expanded diameter portion 617f is larger than that of the circumferential surface 617c in the ninth embodiment shown in Fig. 14 and Fig. 15. Therefore, when the rotation speed of the outer pin 617 is the same, the circumferential speed of the circumferential surface 617c increases in proportion to the diameter. As a premise, the outer pin 617 rotates at a constant speed when it comes into contact with the external gear 614 as an internal pin of the internal gear 616 in accordance with the relative rotation of the carriers 618, 620 and the casing 622 about the central axis 6La.

[0273] When the rotating peripheral surface 617c comes into contact with the outer peripheral surface 649b of the peripheral recesses 646, 647, in an ideal rotation state, the peripheral surface 617c and the outer peripheral surface 649b are in rolling contact. However, if the peripheral speed of the outer pin 617 differs too much from the peripheral speed of the outer peripheral surface 649b, the peripheral surface 617c and the outer peripheral surface 649b will be in sliding contact. Compared to rolling contact, sliding contact can cause phenomena such as increased wear, increased heat generation, shorter product life, increased noise, and an increased failure rate, and there is a demand for an improvement in this regard.

[0274] 16, the outer pin 617 is thickened by providing the expanded diameter portion 617f as described above, thereby reducing the state of sliding contact between the circumferential surface 617c and the outer peripheral surface 649b and maintaining a state of rolling contact, thereby making it possible to adjust the circumferential speed of the outer pin 617. That is, by providing the expanded diameter portion 617f on the outer pin 617, sliding resistance from the carriers 618, 620 is reduced, and the outer pin 617 can be rotated mainly due to contact resistance with the external gear 614.

[0275] This makes it possible to make the rotational speeds of the many outer pins 617 uniform, thereby improving the stability of the relative rotation between the carriers 618, 620 and the casing 622 around the central axis 6La. The preferable rotation speed of the outer pin 617 varies depending on the diameters of the carriers 618, 620 and the casing 622, the relative rotational state thereof about the central axis 6La, and other factors.

[0276] In this way, by forming the expanded diameter portion 617f to expand the diameter of the outer pin 617 and increasing the circumferential speed of the circumferential surface 617c that contacts the outer peripheral surface 649b, the circumferential speed of the outer pin 6178 can be made closer to the circumferential speed of the outer peripheral surface 649b even if the rotation speed of the outer pin 617 is the same. This makes it possible to easily match the relative rotation speed between the carriers 618, 620 and the casing 622. Therefore, the efficiency of adjusting the rotation speed of a large number of outer pins 617 can be improved.

[0277] In other words, in the reducer 600 of this embodiment shown in FIG. 16, the peripheral speed at the peripheral surface 617c of the enlarged diameter portion (bush) 617f is faster than at the position where it contacts the pin groove 616b. Since the outer pins 617 are in contact with the outer peripheral surface 649b while rotating at a high speed, it is ideally preferable that the peripheral speed of the peripheral surface 617c that contacts the outer peripheral surface 649b be the same for all of the outer pins 617.

[0278] Here, the greater the relative speed of contact, the greater the effect of adjusting for speed variations in the outer pins 617, i.e., suppressing variations in circumferential speed. For this reason, by forming the expanded diameter portions 617f, it is possible to make the rotation speeds of the many outer pins 617 uniform and make the circumferential speeds of all the outer pins 617 the same. Therefore, it is possible to suppress variations in the peripheral speed of the many outer pins 617.

[0279] 16, the reduction gear 600 of this embodiment can increase the peripheral speed at the position of contact with the outer peripheral surface 649b by increasing the diameter dimension with the expanded diameter portion 617f without affecting the external gear (oscillating gear) 614 that meshes with the outer pin 617 on the radially inner side. This provides the effect of easily making the rotation speeds of the many outer pins 617 uniform.

[0280] In this embodiment shown in FIG. 16, it is possible to achieve the same effects as the above-described embodiments.

[0281] In the present embodiment shown in FIG. 16, the expanded diameter portion 617f is formed on both ends of the outer pin 617, but it is also possible to form the expanded diameter portion 617f on only one side.

[0282] An eleventh embodiment of a reducer according to the present invention will now be described with reference to the drawings. Fig. 17 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the tenth embodiment shown in Fig. 16 in that the carrier is divided. Other components corresponding to those of the ninth embodiment shown in Figs. 14 and 15 and the tenth embodiment shown in Fig. 16 are designated by the same reference numerals and will not be described.

[0283] In the reducer 600 of this embodiment, as shown in Fig. 17, the first carrier (shaft flange) 618 is divided into two pieces in the direction of the central axis 6La. Here, the dividing surface has the central axis 6La as its normal line and can coincide with the annular surface 649a, as shown by the dashed line in Fig. 17. Here, the first carrier (shaft flange) 618 is divided into an inner shaft flange 618a on the side surrounding the internal space of the reducer 600 and an outer shaft flange 618b on the side facing the outside of the reducer 600.

[0284] The inner shaft flange 618a is located on the side surrounding the internal space of the reducer 600. The periphery of the inner shaft flange 618a coincides with the outer peripheral surface 649b. The thickness of the inner shaft flange 618a is set to be equal to the axial dimension of the outer peripheral surface 649b. The outer shaft flange 618b is located on the side facing the outside of the reducer 600. A portion of the periphery of the outer shaft flange 618b coincides with the annular surface 649a. The first carrier (shaft flange) 618 is configured such that an inner shaft flange 618a and an outer shaft flange 618b are stacked in a direction along the central axis 6La.

[0285] Similarly, in the reducer 600 of this embodiment, the second carrier (hold flange) 620 can be divided into two pieces in the direction of the central axis 6La, as shown in Fig. 17. In this case, the dividing surface can be normal to the central axis 6La and coincide with the annular surface 649a, as shown by the dashed line in Fig. 17. Here, the second carrier (hold flange) 620 is divided into an inner hold flange 620a on the side surrounding the internal space of the reducer 600 and an outer hold flange 620b on the side facing the outside of the reducer 600.

[0286] The inner hold flange 620a is located on the side that surrounds the internal space of the reducer 600. The periphery of the inner hold flange 620a coincides with the outer peripheral surface 649b. The thickness of the inner hold flange 620a is set to be equal to the axial dimension of the outer peripheral surface 649b. The outer hold flange 620b is located on the side facing the outside of the reducer 600. A portion of the periphery of the outer hold flange 620b coincides with the annular surface 649a. The second carrier (hold flange) 620 is configured such that an inner hold flange 620a and an outer hold flange 620b are stacked in a direction along the central axis 6La.

[0287] The four flanges, ie, the inner shaft flange 618a, the outer shaft flange 618b, and the inner hold flange 620a and the outer hold flange 620b, are all connected to a carrier pin (inner pin) 638 by a bolt 638a and fixed to one another.

[0288] In this configuration, when assembling the reducer 600, first, the input shaft 612 and its surrounding members, the outer pin 617, the external gear 614, etc. are housed in the casing 622. In this state, the inner shaft flange 618a and the inner hold flange 620a are assembled so as to come into contact with the enlarged diameter portions 617f of the outer pins 617.

[0289] Furthermore, a carrier pin 638 is inserted into the carrier pin hole 639, and the outer shaft flange 618b and the outer hold flange 620b are positioned in contact with or close to the end face 617b of the outer pin 617, and these four are connected to the carrier pin (inner pin) 638 by a bolt 638a.

[0290] As a result, when assembling the reducer 600, there is no influence due to the formation of the enlarged diameter portion (bush) 617f on the outer pin 617, and it is possible to shorten the assembly time and improve efficiency. Furthermore, the outer peripheral surface 649b with which the outer pin 617 comes into contact can be formed simply by machining the outer peripheral contours of the inner shaft flange 618a and the inner hold flange 620a, which improves ease of machining. When the carrier pin 638 is formed integrally with the first carrier (shaft flange) 618, it can be formed integrally with the inner shaft flange 618a.

[0291] In this embodiment shown in FIG. 17, it is possible to achieve the same effects as the above-described embodiments.

[0292] In this embodiment shown in FIG. 17, it is also possible to adopt a configuration in which the outer pin 617 does not have the expanded diameter portion 617f, as in the ninth embodiment shown in FIGS.

[0293] A twelfth embodiment of a reducer according to the present invention will now be described with reference to the drawings. Fig. 18 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the ninth to eleventh embodiments shown in Figs. 14 to 17 above in terms of the main bearings, and other components corresponding to those of the ninth to eleventh embodiments shown in Figs. 14 to 17 above are designated by the same reference numerals and will not be described again.

[0294] 18, in the reducer 600 of this embodiment, a cross roller bearing is provided as a main bearing 624 at a position that is to be one end of the outer pin 617. The other end of the outer pin 617 also serves as a main bearing 626, similar to the ninth to eleventh embodiments shown in FIGS. In the main bearing 626, the pin groove 616b forming the outer peripheral surface covers the entire length along the central axis 6La of the outer pin 617. The pin groove 616b extends from a radially outer position of the external gear 614 to a radially outer position of the second carrier 620.

[0295] Therefore, the casing 622 integrally formed with the internal gear 616 also extends to a radially outer position of the second carrier 620, similar to the pin groove 616b. In this way, the outer pins 617 and pin grooves 616 b that form the internal teeth of the internal gear 616 can be considered to be formed integrally with the inner peripheral surface 648 of the main bearing 626 .

[0296] Main bearing 624 has an outer ring 624a that rotates integrally with casing 622, an inner ring 624b that rotates integrally with first carrier 618, and rollers 624c that serve as rolling elements. V-grooves with a V-shaped cross section are formed on the opposing surfaces of outer ring 624a and inner ring 624b. A plurality of rollers 624c are sandwiched between outer ring 624a, inner ring 624b, and the V-grooves, and are arranged alternately with their axes perpendicular to each other.

[0297] The main bearing 624, which is a cross roller bearing, is adjacent to the output side of the outer pin 617 in the direction along the central axis 6La. An outer ring 624a is adjacent to the output side end of the outer pin 617. The inner ring 624b is disposed apart from the external gear 614 located on the output side in the direction along the central axis 6La. The main bearing 624, which is a cross roller bearing, is preferably constructed from metal.

[0298] Outer ring 624a is attached to a recess formed in casing 622. In the present embodiment shown in Fig. 18, member 650, which serves as a fixed member or output member, is attached to casing 622 with bolts 650a, and outer ring 628a of main bearing 624 is sandwiched in this attachment portion. In other words, the casing 622 and the member 650 integral with the casing 622 cover the outer ring 624a of the main bearing 624. The inner ring 624b of the main bearing 624 is attached to the outside of the first carrier 618 in the radial direction.

[0299] 18, a reducer 600 of this embodiment has a flange portion 638b at an end on the output side of a carrier pin 638. The end on the output side of the carrier pin 638 passes through a hole portion 618d of the first carrier 618. The end on the output side of the carrier pin 638 is fixed to the first carrier 618 by the flange portion 638b. The input side end of carrier pin 638 is fitted into hole 620d of second carrier 620. A male thread 638e is formed on the input side end of carrier pin 638, and carrier pin 638 is fixed to second carrier 620 by a nut 638d. Carrier pin 638 is surrounded by a tubular inner roller 637 in an annular shape. The carrier pin (inner pin) 638 is inserted into and passes through a carrier pin hole (inner pin hole) 639 formed through the external gear 614 with a gap therebetween.

[0300] 18, an input shaft bearing 634 supports the output side end of the input shaft 612. Here, a motor shaft or the like (not shown) can be connected to the input side of the input shaft 612, and the input side of the input shaft 612 can be supported by a bearing for the motor shaft or the like. For this reason, a bearing is not shown on the input side of the input shaft 612.

[0301] 18, the output-side main bearing 624 is a cross roller bearing, which reduces resistance through rolling contact and stabilizes the relative rotation between the carriers 618, 620 and the casing 622. In particular, this improves the positional stability of the carriers 618, 620 and the casing 622 in the thrust direction during rotation.

[0302] In this embodiment shown in FIG. 18, it is possible to achieve the same effects as the above-described embodiments.

[0303] A thirteenth embodiment of a reducer according to the present invention will be described below with reference to the drawings. Fig. 19 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the twelfth embodiment shown in Fig. 18 above in terms of the main bearings, and other components corresponding to those of the twelfth embodiment shown in Fig. 18 above are assigned the same reference numerals and description thereof will be omitted.

[0304] In the reducer 600 of this embodiment, as shown in FIG. 19, the input side end of the outer pin 617 also serves as the main bearing 626, similar to the twelfth embodiment shown in FIG. In the main bearing 626, the pin groove 616b forming the outer peripheral surface 648 does not cover the entire length along the central axis 6La of the outer pin 617. In other words, the pin groove 616b is located radially outside the external gear 614, and is not provided radially outside the second carrier 620.

[0305] The casing 622 covers the radially outer position of the external gear 614, as does the pin groove 616b. The casing 622 does not extend to the radially outer position of the second carrier 620. The input-side end face 622a of the casing 622 may be flush with the output-side end face of the second carrier 620 at an inner peripheral position close to the central axis 6La. Therefore, the outer pins 617 do not contact the pin grooves 616b at the radially outer position of the second carrier 620.

[0306] In the reducer 600 of this embodiment shown in FIG. 19, the casing 622 is not provided radially outside the second carrier 620, thereby enabling further weight reduction. In this embodiment shown in FIG. 19, it is possible to achieve the same effects as the above-described embodiments.

[0307] A fourteenth embodiment of a reducer according to the present invention will be described below with reference to the drawings. Figure 20 is a cross-sectional view of the reducer of this embodiment taken along the axial direction. This embodiment differs from the twelfth and thirteenth embodiments shown in Figures 18 and 19 described above in terms of the main bearings. Other components corresponding to those of the twelfth and thirteenth embodiments shown in Figures 18 and 19 described above are designated by the same reference numerals, and description thereof will be omitted.

[0308] In the reducer 600 of this embodiment, as shown in Fig. 20, the input side end of the outer pin 617 doubles as the main bearing 626, similar to the thirteenth embodiment shown in Fig. 19 described above, and is not covered by the pin groove 616b which forms the outer peripheral surface 648. Also, the input side end of the outer pin 617 is provided with an expanded diameter portion 617f, similar to the tenth embodiment shown in Fig. 16 described above.

[0309] An expanded diameter portion 617f is provided on the outer pin 617 of the main bearing 626 at a portion on the input side that is not in contact with the pin groove 616b. The outer pin 617 is provided with the expanded diameter portion 617f at a portion that is closer to the input side in the axial direction than the end face 622a of the casing 622. The expanded diameter portion 617f is provided on a portion of the outer pin 617 that is exposed from the pin groove 616b. The expanded diameter portion 617f is sandwiched between the end face 622a and the annular surface 649a in the direction of the central axis 6La. A portion of the expanded diameter portion 617f that is located radially outward of the second carrier 620 in the direction of the central axis 6La is exposed outward beyond the circumferential recess 647.

[0310] As a result, on the output side of reducer 600, main bearing 624, which is a cross roller bearing, stabilizes positioning in the thrust direction, and main bearing 624 made of metal ensures stability in the rotational operation of casing 622 and carriers 618, 620. At the same time, on the input side of the reducer 600, the position of the expanded diameter portion 617f on the output side in the direction of the central axis 6La is restricted by the end face 622a, and the position of the expanded diameter portion 617f on the output side in the direction of the central axis 6La is restricted by the annular surface 649a, thereby restricting the positions of the casing 622 and the carriers 618, 620 in the direction of the central axis 6La. Therefore, the operational stability of the reducer 600 can be improved.

[0311] In this embodiment shown in FIG. 20, it is possible to achieve the same effects as the above-described embodiments.

[0312] In the present invention, the individual configurations in the above-described embodiments may be individually combined, or specific configurations may not be individually adopted or combined.

[0313] Furthermore, PAEKs (Polyaryletherketones) also include PEK (Polyetherketone), PEKK (Polyetherketoneketone), PEKKEK (Polyetherketoneketoneetherketone), and the like. [Industrial Applicability]

[0314] Examples of applications of the present invention include equipment that is physically close to humans, such as service robots, collaborative robots, and power-assisted devices, and can achieve the effect of intrinsic safety due to its lightweight nature. [Explanation of symbols]

[0315] 100,200,300,400,500,600...Reducer 1La, 2La, 3La, 4La, 5La, 6La...Central axis line (principal axis line) 112, 212, 312, 512, 612...Input shaft (eccentric body) 112a,212a,312a,410a,410b,503,612a...Eccentric part 114, 214, 314, 414, 416, 514, 614...External gear 116, 216, 316, 417A, 516, 616...Internal gear 116b, 216b, 316b, 422b, 516b, 616b...Pin groove 117, 217, 317, 417, 517, 617...Outer pin (internal pin) 118, 218, 318, 404a, 518, 618...First carrier (shaft flange) 120, 220, 320, 404b, 520, 620...Second carrier (hold flange) 122,222,322,422,522,622…Casing 124, 224, 324, 424, 524, 624...Main bearing 126,226,326,426,526,626...Main bearing 148, 248, 348, 448, 548...Inner sliding surface 149, 249, 349, 449, 549...Peripheral sliding surface 221...First cover 223...Second cover 144, 145, 244, 245, 444, 445, 544, 545...Metal rings 348a,348b...projection 360…Groove 361...Diameter groove (groove) 362,363…Peripheral groove (groove) 404,519…Career 408...Input shaft 410...Crankshaft (eccentric body) 617b...End face 617c...peripheral surface 617f...Expanded diameter part 646,647...peripheral recess 648…Inner peripheral surface 649a...Ring 649b…Outer surface 624a...outer ring 624b…Inner circle 624c…Laura

Claims

[Claim 1] Casing surrounding the main axis and an internal gear having a plurality of outer pins rotatably arranged in pin grooves provided on the inner periphery of the casing; an external gear that meshes with the internal gear; an eccentric body that oscillates the external gear; a carrier that rotates relative to the casing; a main bearing having an inner sliding surface formed on an inner periphery of a metal ring that rotates integrally with the casing and an outer sliding surface formed on an outer periphery of the carrier; and the casing and the carrier are made of resin, The metal ring and the outer pin are arranged at a position where they overlap in a direction along the main axis. reducer.

Images