JP2021071189A - Reduction gear - Google Patents

Abstract

To improve torque density as compared with a conventional reduction gear.SOLUTION: A reduction gear (1) includes an external tooth gear (14), a carrier (20) synchronized with an autorotation component of the external tooth gear (14) and an inner pin (21) for transmitting the autorotation component of the external tooth gear (14) to the carrier (20). The external tooth gear (14) has an inner pin hole (14h) arranged on a position offset from a rotation center line of the carrier (20) to insert the inner pin (21). In a cross-sectional shape of the inner pin (21) on a face vertical to a center axis (O1), a radial direction width (b1) along a radial direction of the center axis (O1) is smaller than a tangent direction width (a1) along a direction vertical to the radial direction. In a cross-sectional shape of the inner pin hole (14h) on a face vertical to the center axis (O1), a radial direction width (b2) along the radial direction of a center axis (O2) of the external tooth gear (14) is smaller than a tangent direction width (a2) along the direction vertical to the radial direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a speed reducer.

Conventionally, an eccentric swing type speed reducer that obtains a decelerated output by using an eccentric swing type external gear is known (see, for example, Patent Document 1).
In this type of reduction gear, for example, as shown in FIG. 7, a cylindrical inner pin provided in a carrier which is an output shaft is inserted into a circular inner pin hole provided in an outer gear. As a result, the rotation component of the eccentrically oscillated external gear is transmitted to the carrier via the inner pin.

Japanese Unexamined Patent Publication No. 2016-102529

In the above-mentioned conventional reduction gear, the bending stress generated at the root of the inner pin rather than the load from the external gear during torque transmission becomes a problem. Further, in the external tooth gear, the gear load generated in the thin-walled portion on the outer diameter side of the inner pin hole and the load generated from the eccentric bearing on the thin-walled portion on the inner diameter side of the inner pin hole become problems.
These strength problems became a constraint, and it was difficult to increase the torque density (output torque per unit weight of the reduction gear).

An object of the present invention is to improve the torque density as compared with the conventional case.

The present invention is an eccentric swing type speed reducer including an external gear, a carrier that synchronizes with the rotation component of the external gear, and an internal pin that transmits the rotation component of the external gear to the carrier. hand,
The external gear has an internal pin hole that is arranged at a position offset from the rotation center line of the carrier and through which the internal pin is inserted.
The cross-sectional shape of the inner pin on the plane perpendicular to the rotation center line has a radial width with respect to the rotation center line smaller than a width in the direction perpendicular to the radial direction.
In the cross-sectional shape of the inner pin hole on the plane perpendicular to the rotation center line, the width in the second radial direction with respect to the rotation center of the external gear is smaller than the width in the direction perpendicular to the second radial direction. It was configured.

According to the present invention, the torque density can be improved as compared with the conventional case.

It is sectional drawing of the speed reduction apparatus which concerns on embodiment of this invention. It is sectional drawing of the reduction gear in line AA of FIG. It is a figure which shows the modification of the inner pin. It is a partial cross-sectional view for demonstrating another modification of an inner pin. It is a figure which shows the modification of the inner pin hole. It is a figure which shows the other modification of the inner pin hole. It is a figure which shows the external tooth gear and a carrier in a conventional reduction gear.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Overall configuration of speed reducer>
FIG. 1 is a cross-sectional view of a speed reducer according to an embodiment of the present invention.
As shown in this figure, the speed reducer 1 of the present embodiment is a center crank type eccentric swing type speed reducer. The reduction gear 1 includes an input shaft 12 having a first eccentric body 12b and a second eccentric body 12c, two external gears 14 (first external gear 15 and a second external gear 16), and two external gears. An internal gear 18 that meshes with the gear 14 and a carrier 20 having an internal pin 21 are provided. Further, the reduction gear 1 includes a first cover 22, a second cover 24, a third cover 26, eccentric bearings 31, 32, carrier bearings 34, 35, and input shaft bearings 37, 38.

The input shaft 12 has a shaft portion 12a centered on the rotation shaft O1 and a first eccentric body 12b and a second eccentric body 12c provided eccentrically by an eccentric amount e from the rotation shaft O1 (see FIG. 2). .. The first eccentric body 12b and the second eccentric body 12c have a circular cross section perpendicular to the rotation axis O1, and the rotation of the input shaft 12 causes eccentric rotation in different phases.
In the following description, unless otherwise specified, the direction along the rotation axis O1 is "axial direction", the direction perpendicular to the rotation axis O1 is "diametrical direction", and the rotation direction centered on the rotation axis O1 is "axial direction". It is called "circumferential direction". The inner side in the radial direction is called the "inner diameter side", and the outer side in the radial direction is called the "outer diameter side". Further, among the axial directions, the direction in which the input shaft 12 is exposed (right side in FIG. 1) is referred to as an input side, and the direction in which the carrier 20 is exposed (left side in FIG. 1) is referred to as a load side. However, in the description of the external gear 14 and the internal pin hole 14h offset from the rotating shaft O1, the direction perpendicular to the central axis (rotation center) O2 of the external gear 14 is referred to as the "radial direction" as described later. The direction of rotation about the central axis O2 is called the "circumferential direction".

The input shaft 12 is an integrally molded product made of, for example, a resin material, including the shaft portion 12a, the first eccentric body 12b, and the second eccentric body 12c. When composed of a resin material, high strength between each part can be obtained by forming an integrally molded product. As the resin material, for example, POM, PEEK, FRP (Fiber-Reinforced Plastic), CFRP (Carbon Fiber Reinforced Plastic) and the like can be applied. However, the present invention is not limited to these, and various resin materials such as paper bake material and cloth bake material may be applied as the resin material.
The input shaft 12 may be partially or wholly made of a metal material, or may have a plurality of parts formed as separate bodies and connected to each other. As the metal material, a metal having a specific gravity lower than that of iron such as aluminum, an aluminum alloy, and a magnesium alloy may be applied, or an iron-based metal may be applied.

The two external gears 14 are made of a resin material. Specific examples of the resin material are the same as those described above. Of these, the first external gear 15 is incorporated into the first eccentric body 12b via an eccentric bearing 31, and swings as the input shaft 12 rotates. On the other hand, the second external gear 16 is incorporated into the second eccentric body 12c via the eccentric bearing 32, and the input shaft 12 rotates to swing in a phase different from that of the first external gear 15. A wrinkle 28 is arranged between the first external gear 15 and the second external gear 16 so as to provide an interval.

In each of the two external gears 14, a plurality of inner pin holes 14h through which the inner pins 21 of the carrier 20 are passed are separated in the circumferential direction at positions offset in the radial direction from the rotation axis O1. It is provided (see FIG. 2). The inner pin hole 14h of the first external gear 15 and the inner pin hole 14h of the second external gear 16 are arranged so as to partially overlap each other, and the inner pin 21 is passed through the overlapping portion. Each inner pin 21 is in contact with the inner peripheral surface of the inner pin hole 14h of the first outer gear 15 and is in contact with the inner peripheral surface of the inner pin hole 14h of the second outer gear 16. It is passed through the hole 14h.
The specific shape of the inner pin hole 14h will be described later.

The internal gear 18 meshes with the external teeth in the maximum eccentric direction of the first external gear 15 and the external teeth in the maximum eccentric direction of the second external gear 16. The internal gear 18 is made of a resin material, but may be made of a metal. Specific examples of the resin material and the metal material are the same as those described above.

The carrier 20 is connected to two external gears 14 via an integrally molded inner pin 21, and rotates in synchronization with the rotation of the two external gears 14. That is, the inner pin 21 transmits the rotation component of the two external gears 14 to the carrier 20. The carrier 20 has a shaft portion 20a having a rotation shaft O1 as a central axis (rotation center line). The carrier 20 having the shaft portion 20a and the plurality of inner pins 21 is an integrally molded product made of a resin material. By making it an integrally molded product, high strength between each part can be obtained. Specific examples of the resin material are the same as those described above.
The specific shape of the inner pin 21 will be described later.

The first cover 22 covers one of the internal gears 18, the two external gears 14 and the internal pin 21 in the axial direction (load side), and the second cover 24 covers the other (input side) in the axial direction. .. The first cover 22, the second cover 24, and the internal gear 18 are connected via the connecting member 41.
The first cover 22 rotatably supports the shaft portion 20a of the carrier 20 via the carrier bearings 34 and 35. The second cover 24 rotatably supports the shaft portion 12a of the input shaft 12 via the input shaft bearings 37 and 38. The third cover 26 is fixed to the first cover 22 via a screw 42 in one axial direction (load side) and covers one axial direction (load side) of the carrier bearings 34 and 35.
The first cover 22, the second cover 24, and the third cover 26 are made of a resin material, but a part or all of them may be made of a metal. Specific examples of the resin material and the metal material are the same as those described above.

The eccentric bearings 31 and 32 are, for example, ball bearings, and have an inner ring, a rolling element, and an outer ring.
The carrier bearings 34 and 35 are, for example, ball bearings, and have an inner ring, a rolling element, and an outer ring.
The input shaft bearings 37 and 38 are, for example, ball bearings, and have an inner ring, a rolling element, and an outer ring. The input shaft bearing 38 is fixed by applying pressure in the axial direction from the pressure screw 43 screwed into the screw hole of the second cover 24.
The eccentric body bearings 31 and 32, the carrier bearings 34 and 35 and the input shaft bearings 37 and 38 are made of metal, but these may also be made of the resin material described above. Further, the eccentric body bearings 31 and 32, the carrier bearings 34 and 35 and the input shaft bearings 37 and 38 may have a configuration in which the inner ring, the outer ring, or both of them are omitted, and a type of bearing other than the ball bearing is adopted. May be good.

<Shape of inner pin>
FIG. 2 is a cross-sectional view of the speed reducer 1 along the line AA of FIG. 1, FIG. 3 is a diagram showing a modified example of the cross-sectional shape of the inner pin 21, and FIG. 4 is a diagram showing a modified example of the cross-sectional shape of the inner pin 21. It is a partial cross-sectional view for demonstrating the modification of. In FIG. 3, the vertical direction of the paper surface corresponds to the radial direction (the upper side corresponds to the outer diameter side).
Each inner pin 21 is cantilevered from the shaft portion 20a of the carrier 20 along the axial direction, and in the present embodiment, the cross-sectional shape on the plane perpendicular to the axial direction (hereinafter, simply “cross-sectional shape””. ) Is formed in a uniform shape. As shown in FIG. 2, the cross-sectional shape of the inner pin 21 of the present embodiment is formed in an elliptical shape elongated in the circumferential direction. More specifically, the cross-sectional shape of the inner pin 21 is formed in an elliptical shape in which the short axis substantially follows the radial direction and the long axis substantially follows the circumferential direction (to be exact, the direction perpendicular to the radial direction in the cross section). ing.

The cross-sectional shape of the inner pin 21 is not limited to an elliptical shape, and the radial width b1 along the radial direction may be smaller than the tangential width a1 along the direction perpendicular to the radial direction. Here, "~ width" means the maximum width of the inner pin 21 along the direction, and in the present embodiment, the tangential width a1 corresponds to the long axis and the radial width b1 corresponds to the short axis. Therefore, this cross-sectional shape may be an oval shape (rounded rectangle) shown in FIG. 3 (a), or as shown in FIG. 3 (b), both sides in the radial direction are cut out based on the circle. It may have a notch shape or the like. In the case of the notch shape, the notch portion does not have to be flat, and may be concave or convex as shown in FIGS. 3 (c) and 3 (d), or may be a flat cut as shown in FIG. 3 (e). The shape may be such that both sides of the notch are chamfered. In FIGS. 3 (c) to 3 (e), only the outer diameter side (diameter outside: upper side in the drawing) of the center 21c is cut out, but the inner diameter side (diameter inside:) of the center 21c is shown. The lower side in the figure) may also be cut out. In this case, the cutouts having different shapes on the outer diameter side and the inner diameter side may be used.
Thereby, for example, the cross-sectional coefficient in the circumferential direction of the inner pin 21 can be increased as compared with the case where the inner pin 21 has a circular cross section.

Further, the cross-sectional shape of the inner pin 21 does not have to be uniform in the axial direction.
In this case, it is preferable that the cross-sectional area of the base end portion of the inner pin 21 (cross-sectional area perpendicular to the axial direction) is larger than the cross-sectional area of the portion on the tip end side from the base end portion. As a result, the stress generated at the base (base end surface) of the inner pin 21 during torque transmission can be relaxed. In this case, the base end portion of the inner pin 21 having a large cross-sectional area may overlap with the first external gear 15 in the axial direction.
Further, in this case, as shown in FIG. 4, it is more preferable that the base end portion 21d of the inner pin 21 has a step portion in which the cross-sectional area gradually increases toward the base end side (load side). Then, this step portion may be used as a regulating portion (regulating surface) for restricting the movement of the first external gear 15 to the axial load side. As a result, the sliding surface (contact surface) between the carrier 20 and the first external gear 15 is made smaller than in the case where this step is not provided (for example, in the state of FIG. 1), and the external gear 14 is axially smaller. Movement can be regulated.

<Shape of inner pin hole>
Each inner pin hole 14h is provided corresponding to the inner pin 21, and the cross-sectional shape (that is, the shape seen from the axial direction) on the plane perpendicular to the axial direction corresponds to the cross-sectional shape of the inner pin 21. In the present embodiment, the cross-sectional shape of the inner pin hole 14h is formed into an elliptical shape elongated in the circumferential direction as shown in FIG. More specifically, the cross-sectional shape of the inner pin 21 is formed in an elliptical shape in which the short axis substantially follows the radial direction and the long axis substantially follows the circumferential direction (to be exact, the direction perpendicular to the radial direction in the cross section). ing.
However, the external gear 14 is formed in a concentric shape centered on the central axis O2 (rotation center) eccentric from the rotation axis O1 by the amount of eccentricity e. Therefore, the inner pin hole 14h is formed in a shape based on the central axis O2 instead of the rotation axis O1. Hereinafter, in the description of the shape of the inner pin hole 14h, unless otherwise specified, the "diameter direction" refers to the direction perpendicular to the central axis O2, and the "circumferential direction" refers to the rotation direction centered on the central axis O2. To do.

The cross-sectional shape of the inner pin hole 14h is not limited to an elliptical shape, and the radial width b2 along the radial direction of the external gear 14 is larger than the tangential width a2 along the direction perpendicular to the radial direction. It should be small. Here, "~ width" means the maximum width of the inner pin hole 14h along the direction, and in the present embodiment, the tangential width a2 corresponds to the long axis and the radial width b2 corresponds to the short axis. Therefore, the cross-sectional shape of the inner pin hole 14h may be an oval shape (rounded rectangle) as in the inner pin 21, or may be a notch shape in which both sides in the radial direction are cut out based on the circle. You may.
As a result, as compared with the case where the inner pin hole 14h is circular, for example, the wall thickness on the outer diameter side from the inner pin hole 14h to the outer peripheral tooth bottom of the outer gear 14 and the eccentric body bearing 31 from the inner pin hole 14h, The wall thickness on the inner diameter side up to the inner peripheral surface into which the outer ring of 32 is fitted can be increased.

Further, the cross-sectional shape of the inner pin hole 14h is preferably formed in an envelope shape drawn by (the outer edge of) the inner pin 21 when the inner pin 21 swings around with a swing radius of the eccentric amount e. Therefore, for example, when the cross-sectional shape of the inner pin 21 is elliptical, the cross-sectional shape of the inner pin hole 14h is also elliptical as shown in FIG. 5A, and when the cross-sectional shape of the inner pin 21 is oval. As shown in FIG. 5B, it is preferable that the cross-sectional shape of the inner pin hole 14h is also an elliptical shape.
As a result, the rotation component of the external tooth gear 14 that swings eccentrically with the eccentric amount e can be suitably transmitted to the inner pin 21 via the inner pin hole 14h.

Further, as shown in FIG. 6, the cross-sectional shape of the inner pin hole 14h is on the inner diameter side (diameter inside: in the figure) from the center 14hc of the virtual circle having the maximum width (tangential width a2 in the example of the figure) as the diameter. It is preferable that the radial distance c2 to the lower) end is larger than the radial distance d2 from the center 14hc to the outer (radial outer: upper in the figure) end. In this case, the cross-sectional shape of the corresponding inner pin 21 has the same shape. That is, the cross-sectional shape of the inner pin 21 in this case is, for example, as shown in FIGS. 3C to 3E, the radial distance from the center 21c of the virtual circle having the maximum width as the diameter to the inner diameter side end portion. c1 is larger than the radial distance d1 from the center 21c to the outer diameter side end. Here, the radial distance from the inner diameter side end portion or the outer diameter side end portion corresponds to the surface from the center 14hc of the virtual circle to the inner pin hole 14h (or from the center 21c of the virtual circle to the inner pin 21). The largest radial distance on the side.
As a result, the wall thickness on the outer diameter side from the inner pin hole 14h of the outer tooth gear 14 to the tooth bottom of the outer tooth can be made thicker than in the case where the distance c2 is equal to the distance d2, for example (see FIG. 2).

<Operation explanation>
In the speed reducer 1, when power is transmitted from the outside and the input shaft 12 rotates, the first eccentric body 12b and the second eccentric body 12c rotate eccentrically. Then, along with this, the two external gears 14 swing with a phase difference of, for example, 180 degrees. The two external gears 14 are inscribed in mesh with the internal gears 18, and the internal gears 18 are connected to the first cover 22 and the second cover 24. Therefore, each time the input shaft 12 rotates, the two external gears 14 rotate relative to the internal gear 18 by the difference in the number of teeth (rotation). The rotation component of the two external gears 14 is transmitted to the carrier 20 via the inner pin 21. As a result, the rotational movement of the input shaft 12 is decelerated at a reduction ratio of 1 / (the number of teeth common to the two external gears 14) and output to the shaft portion 20a of the carrier 20.

At this time, the inner pin 21 that transmits the rotation component of the external gear 14 to the carrier 20 is formed in a cross-sectional shape in which the radial width b1 is smaller than the tangential width a1. That is, since the width of the inner pin 21 in the circumferential direction is larger than the width in the radial direction, the cross-sectional coefficient of the inner pin 21 in the circumferential direction can be increased as compared with the case of a simple circular cross section. As a result, the bending stress in the circumferential direction generated at the root of the inner pin 21 at the time of torque transmission can be relaxed.
At this time, in the inner pin hole 14h for transmitting the rotation component of the outer gear 14 to the inner pin 21, the radial width b2 perpendicular to the central axis O2 (center of rotation) of the outer gear 14 is perpendicular to the radial direction. It is formed in a cross-sectional shape smaller than the width a2 in the tangential direction. That is, since the width of the inner pin hole 14h in the circumferential direction is larger than the width in the radial direction, the outer diameter side from the inner pin hole 14h to the outer peripheral tooth bottom of the outer gear 14 is compared with the case of a simple circular cross section. And the wall thickness on the inner diameter side from the inner pin hole 14h to the inner peripheral surface can be increased respectively. As a result, the stress acting on the outer peripheral gear of the external gear 14 and the stress acting on the inner peripheral surface of the eccentric bearings 31 and 32 can be relaxed.

<Technical effect of this embodiment>
As described above, according to the speed reducer 1 of the present embodiment, the cross-sectional shape of the inner pin 21 is such that the radial width b1 along the radial direction is larger than the tangential width a1 along the direction perpendicular to the radial direction. small. Therefore, the cross-sectional coefficient in the circumferential direction of the inner pin 21 can be increased as compared with the case of a simple circular cross section, and the bending stress in the circumferential direction generated at the root of the inner pin 21 at the time of torque transmission can be relaxed.
Further, the cross-sectional shape of the inner pin hole 14h is such that the radial width b2 along the radial direction with respect to the central axis O2 (rotation center) of the external gear 14 is tangential width a2 along the direction perpendicular to the radial direction. Is also small. Therefore, as compared with the case of a simple circular cross section, the wall thickness on the outer diameter side from the inner pin hole 14h to the outer peripheral tooth bottom and the wall thickness on the inner diameter side from the inner pin hole 14h to the inner peripheral surface of the outer tooth gear 14 And can be thickened respectively.
As a result, the load capacity of the inner pin 21 and the inner pin hole 14h (external gear 14) can be improved and a larger transmission torque can be tolerated as compared with the conventional case in which the inner pin and the inner pin hole have a circular cross section. Therefore, the torque density can be improved as compared with the conventional case.

The cross-sectional shape of the inner pin hole 14h is such that the radial distance c2 of the external gear 14 from the center 14hc of the virtual circle whose diameter is the maximum width to the inner diameter side end is the outer diameter side end from the center 14hc. It may be configured to be larger than the radial distance d2 up to.
As a result, the wall thickness on the outer diameter side from the inner pin hole 14h of the outer tooth gear 14 to the tooth bottom of the outer tooth can be made thicker than, for example, as compared with the case where the distance c2 is equal to the distance d2. Therefore, in the external gear 14, the stress generated in the outer gear on which a load larger than that on the inner peripheral side acts can be further relaxed.

Further, the cross-sectional shape of the inner pin hole 14h preferably has a portion formed in an envelope shape drawn by the inner pin 21 when the inner pin 21 swings around with a swing radius of the eccentric amount e.
As a result, the rotation component of the external tooth gear 14 that swings eccentrically with the eccentric amount e can be suitably transmitted to the inner pin 21 via the inner pin hole 14h.

Further, the inner pin 21 may be integrally formed with the carrier 20 in a cantilever shape, and the cross-sectional area of the base end portion thereof may be larger than the cross-sectional area of the portion on the tip end side from the base end portion. As a result, the stress generated at the base (base end surface) of the inner pin 21 during torque transmission can be relaxed.
Further, in this case, the base end portion 21d of the inner pin 21 may have a step portion in which the cross-sectional area gradually increases toward the base end side. As a result, the sliding surface (contact surface) between the carrier 20 and the first external gear 15 is made smaller than that in the case where the base end portion 21d does not have a step portion, and the step portion is made of the first external gear 15. It can be used as a regulatory unit that regulates movement to the axial load side.

<Others>
The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the carrier 20 including the inner pin 21 is made of a resin material, but the carrier 20 may be partially or wholly made of metal. Insert molding may be performed in which only the inner pin 21 is made of resin and the remaining portion is made of metal. Similarly, the external gear 14 may also be made of metal. Specific examples of the metal material are the same as those described above. The resin-made one can freely form the inner pin 21 and the inner pin hole 14h, but even if it is made of metal, it can be dealt with by using, for example, a 3D printer.

Further, in the above embodiment, the inner pin 21 is integrally molded with the carrier 20, but the inner pin 21 and the carrier 20 may be formed separately and connected to each other.

Further, the inner pin according to the present invention transmits the rotation component of the external gear to the carrier, and includes a configuration having this function. Therefore, for example, when carriers are on both sides of the input side and the load side and a pin-shaped configuration connects these two carriers, this pin-shaped configuration transmits power (torque) from the external gear to the carrier. If (for example, as described in Japanese Patent No. 5103444), this is included in the inner pin according to the present invention. However, a connecting pin or a carrier pin that connects these two carriers but does not have a torque transmission function (for example, those described in Japanese Patent No. 5791542 and Japanese Patent Application Laid-Open No. 2019-82255) is the present invention. It is not included in the inner pin related to.

Further, in the above embodiment, the center crank type eccentric swing type speed reducer is shown, but the speed reducer according to the present invention is not particularly limited as long as it is an eccentric swing type, for example, a carrier shaft. It includes a so-called distribution type in which an axis having an eccentric body is arranged at a position offset in the radial direction from the center.
In addition, the details shown in the embodiments can be appropriately changed without departing from the spirit of the invention.

1 Speed reducer 12b 1st eccentric body 12c 2nd eccentric body 14 External gear 14h Internal pin hole 14hc Center 15 (of virtual circle of internal pin hole) Center 15 1st external gear 16 2nd external gear 18 Internal gear 20 Carrier 20a Shaft 21 Inner pin 21c (inner pin virtual circle) center 21d Base end a1 (inner pin) tangential width b1 (inner pin) radial width c1 (inner pin virtual circle center to inner diameter side Radial distance to the end d1 Radial distance from the center of the virtual circle of the inner pin to the outer peripheral end a2 Tangent width b2 (of the inner pin hole) Radial direction Width c2 (in the radial direction from the center of the virtual circle of the inner pin hole to the inner diameter side end) Distance d2 (in the radial direction from the center of the virtual circle of the inner pin hole to the outer diameter side end) distance e Eccentricity O1 Rotation axis (rotation center line)
O2 (external gear) central axis (rotation center)

Claims (7)

An eccentric swing type speed reducer including an external gear, a carrier that synchronizes with the rotation component of the external gear, and an internal pin that transmits the rotation component of the external gear to the carrier.
The external gear has an internal pin hole that is arranged at a position offset from the rotation center line of the carrier and through which the internal pin is inserted.
The cross-sectional shape of the inner pin on the plane perpendicular to the rotation center line has a radial width with respect to the rotation center line smaller than a width in the direction perpendicular to the radial direction.
In the cross-sectional shape of the inner pin hole on the plane perpendicular to the rotation center line, the width in the second radial direction with respect to the rotation center of the external gear is smaller than the width in the direction perpendicular to the second radial direction. ,
Decelerator. The cross-sectional shape of the inner pin is such that the radial distance from the center of the virtual circle whose diameter is the maximum width to the inner diameter side end is the radial distance from the center of the virtual circle to the outer diameter side end. Greater than the distance,
The cross-sectional shape of the inner pin hole has the second radial distance from the center of the virtual circle whose diameter is the maximum width to the inner diameter side end portion, and the second radial distance from the center to the outer diameter side end portion. Greater than the radial distance of
The speed reducer according to claim 1. The external gear is eccentric from the rotation center line by a predetermined amount of eccentricity.
The cross-sectional shape of the inner pin hole has a portion formed in an envelope shape drawn by the inner pin when the inner pin swings around with a swing radius of the eccentric amount.
The speed reducer according to claim 1 or 2. The inner pin is made of a resin material.
The speed reducer according to any one of claims 1 to 3. The inner pin
It is integrally molded with the carrier in a cantilever shape.
The cross-sectional area of the base end portion is larger than the cross-sectional area of the portion on the tip end side from the base end portion.
The speed reducer according to claim 4. The inner pin has a stepped portion in which the cross-sectional area gradually increases toward the proximal end side.
The speed reducer according to claim 5. The external gear is made of a resin material.
The speed reducer according to any one of claims 4 to 6.

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