JP7240217B2 - Cycloid reducer, its manufacturing method, and motor unit - Google Patents

Description

The present invention relates to a cycloidal reduction gear, a method for manufacturing the cycloidal reduction gear, and a motor unit provided with the cycloidal reduction gear.

BACKGROUND ART Conventionally, a cycloid reducer (internal planetary gear reducer) consisting of an internal planetary gear mechanism and a constant speed internal gear mechanism is known. A typical cycloid reducer consists of an external gear that can rotate eccentrically with respect to an input shaft, an internal gear that internally meshes with the external gear, a member that extracts only the rotation component of the external gear, and a member connected to the external gear. and an output shaft. For example, Patent Literature 1 discloses a speed reducer in which the internal teeth of an internal gear fixed to a casing are composed of external pins loosely fitted in pin holes.

In this speed reducer, the external gear oscillates and rotates with the rotation of the input shaft, and the rotation of the input shaft is decelerated by the external gear due to the engagement between the external pin corresponding to the internal tooth of the internal gear and the external gear. It is output as a rotation (rotation). By adopting a pin member (outer pin) for the inner tooth of the internal gear as in the reduction gear of Patent Document 1, the internal gear and the external gear are in rolling contact, reducing mechanical loss. It can be made small and high gear efficiency can be obtained.

JP-A-5-44791

However, even if the loss can be reduced by rolling contact between the internal gear and the external gear, the cylindricity of the shape of the groove portion (corresponding to the outer pin hole in Patent Document 1) in which the pin member is rotationally held is a tolerance. If it does not fit inside, the pin member cannot roll smoothly, and loss may increase. Furthermore, in this case, vibration and noise may occur when the pin member rolls and slides on the groove.

The present invention has been devised in view of such problems, and aims to achieve low noise and high efficiency by rotating the pin member that constitutes the internal teeth with low loss. In addition to these purposes, it is also another object of the present invention to achieve functions and effects that are derived from each configuration shown in the modes for carrying out the invention described later and that cannot be obtained by conventional techniques. is.

(1) The cycloid reducer disclosed herein includes an external gear mounted eccentrically rotatably with respect to the rotation center of an input shaft, and a plurality of external gears that rotate while being flexed by internally meshing with the external teeth of the external gear. and a holder having a cylindrical inner surface for rotatably holding each of the outer pins; and a carrier for extracting only the rotation component of the external gear. The holder has a plurality of pin grooves axially recessed on the inner surface for holding the outer pins, and a recessed groove recessed over the entire circumference of the inner surface so as to cross the pin grooves. have Further, the edge of the groove is provided with a rolling surface that comes into surface contact with the outer peripheral surface of the outer pin when the outer pin bends and rotates . The pin groove has an inner diameter larger than the outer diameter of the outer pin at the position of the rolling surface, and the inner diameter at a position other than the rolling surface is equal to the outer diameter of the outer pin. are

(2) It is preferable that the inner surface of the pin groove at a position other than the rolling contact surface is formed into a semi-cylindrical surface having an inner diameter equal to the outer diameter of the outer pin and constant in the axial direction.
(3) Preferably, the holder is made of a material softer than the material of the outer pin, and the rolling surface is formed by sliding contact when the outer pin rotates.

(4) More preferably, the outer pin is made of an iron-based material, and the holder is made of an aluminum-based material.
(5) Further, it is preferable that the cycloid reducer includes a guide portion that maintains a constant axial positional relationship between the external gear, the holder, and the outer pin.

(6) The manufacturing method disclosed herein includes an external gear mounted eccentrically rotatably with respect to the rotation center of an input shaft, and a plurality of external gears rotating while being internally meshed with the external teeth of the external gear. A method of manufacturing a cycloid reduction gear comprising an internal gear having an outer pin and a holder for rotatably holding each of the outer pins, and a carrier for taking out only the rotation component of the external gear. In this manufacturing method, a plurality of pin grooves extending in the axial direction for holding the outer pins are formed on the cylindrical inner surface of the part to be the holder, and the pin grooves extend along the entire circumference of the inner surface so as to traverse the pin grooves. and a groove forming step of forming a groove extending in a vertical direction, and rotating the input shaft so that the outer pin bends toward the inside of the groove and rotates, thereby making sliding contact with the edge of the groove. and a rolling surface forming step of forming a rolling surface with the rolling surface.

In the groove forming step, the inner surface of the pin groove is formed into a semi-cylindrical surface having an inner diameter equal to the outer diameter of the outer pin and constant in the axial direction. The rolling surface is ground so that the inner diameter at the position of (1) is larger than the inner diameter at positions other than the rolling surface .

( 7 ) A motor unit disclosed herein is a motor having a cycloid reducer according to any one of (1) to (5) above, and a motor rotation shaft coupled to the input shaft of the cycloid reducer. and equipped with.

According to the disclosed means, it is possible to rotate the outer pin that constitutes the inner tooth with low loss, so it is possible to achieve low noise and high efficiency.

It is a figure which shows the motor unit which concerns on embodiment, shows a cycloidal reduction gear with an axial sectional view, and shows a motor with a schematic diagram. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1; FIG. 2 is a perspective view showing an outer pin holder provided in the cycloid speed reducer of FIG. 1; FIG. 2 is a perspective view of the cycloid reducer of FIG. 1; It is a figure for demonstrating the rolling surface of the cycloid reduction gear of FIG. 1, and shows the drive state of a reduction gear. FIG. 2 is a diagram for explaining a rolling surface of the cycloid reducer in FIG. 1 and shows a stopped state of the reducer; It is an example of a flow chart explaining a manufacturing method of a cycloid reduction gear concerning an embodiment.

A cycloid reducer, a method for manufacturing the same, and a motor unit as embodiments will be described with reference to the drawings. The embodiments shown below are merely examples, and there is no intention to exclude various modifications and application of techniques not explicitly described in the embodiments below. Each configuration of this embodiment can be modified in various ways without departing from the gist thereof. Also, they can be selected or combined as needed.

[1. composition]
FIG. 1 is a view showing a motor unit of the present embodiment, showing a cross-sectional view of a cycloid reducer 1 (hereinafter referred to as "reducer 1") cut in the axial direction and a schematic diagram of a motor 10. As shown in FIG. A partially enlarged view is shown in the lower right of the figure. The speed reducer 1 is an internal planetary gear speed reducer comprising an internal planetary gear mechanism and a constant speed internal gear mechanism. The speed reducer 1 of the present embodiment is unitized by being connected to the motor 10, and reduces the rotational speed of the motor 10 and outputs it. The motor 10 is, for example, a DC motor having a rotor (not shown) that rotates integrally with the motor rotating shaft 11 and a stator (not shown) fixed to the motor casing 12 . The motor 10 shown in FIG. 1 is an example, and its type, size and shape are not particularly limited.

A speed reducer 1 of this embodiment includes an input shaft 2 , an output shaft 3 , an external gear 4 , an internal gear 5 , a carrier 6 and a case 7 . Each element will be described below with reference to FIGS. 1 to 6. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, FIG. 3 is a perspective view showing an outer pin holder 51 (holder) described later, and FIG. 5 and 6 are diagrams for explaining a main part of the speed reducer 1. FIG. 5 shows the drive state of the speed reducer 1, and FIG. 6 shows the stop state of the speed reducer 1.

As shown in FIG. 1, the input shaft 2 is a hollow shaft through which the power of the motor 10 is input to the reduction gear 1, and is connected to the motor rotation shaft 11 (indicated by the dashed line in FIG. 1) of the motor 10. be done. The input shaft 2 of the present embodiment includes a cylindrical portion 2a having a center axis of the rotation center C, an eccentric portion 2b formed in an axially intermediate portion of the cylindrical portion 2a, and an inner peripheral surface of the cylindrical portion 2a. and a keyway 2c recessed along it. The center of rotation C of the cylindrical portion 2 a coincides with both the center of the motor rotation shaft 11 of the motor 10 and the center of rotation of the output shaft 3 .

The eccentric portion 2b is a cylindrical portion that protrudes radially outward from the outer peripheral surface of the cylindrical portion 2a. The center C' of the eccentric portion 2b is slightly displaced from the rotation center C of the cylindrical portion 2a. The key groove 2c is a groove into which a key (not shown) for connecting the input shaft 2 and the motor rotating shaft 11 of the motor 10 is fitted. An inner ring of a ball bearing 9 (second rolling bearing) is fixed to both end portions of the cylindrical portion 2a. Both ends of the input shaft 2 are rotatably supported by the ball bearings 9 .

The output shaft 3 is a hollow shaft for outputting the power amplified by the speed reducer 1 and is arranged coaxially with the cylindrical portion 2a of the input shaft 2 . The output shaft 3 of the present embodiment is composed of a cylindrical portion 3a having the center axis of the rotation center C and a flange portion 3b formed at one end of the cylindrical portion 3a. The flange portion 3b is a portion for connecting the output shaft 3 and the carrier 6, and is formed with a plurality of through holes (not shown). A fastener 31 for coupling with the carrier 6 is fastened to each through hole. It should be noted that the driven object may be directly connected to the carrier 6 to take out the output, in which case the output shaft 3 can be omitted.

The external gear 4 is a gear attached to the rotation center C of the input shaft 2 so as to be eccentrically rotatable. As shown in FIGS. 1 and 2, the external gear 4 of this embodiment is fitted on the eccentric portion 2b of the input shaft 2 so as to be relatively rotatable via a needle roller bearing 21. As shown in FIG. The external gear 4 is regulated by the washer 22 described above so as not to shift its axial position.

As shown in FIG. 2, the outer periphery of the external gear 4 is provided with external teeth 4t such as a trochoid tooth profile or an arc tooth profile. In addition, the external gear 4 has a plurality of cylindrical carrier pin holes 4h extending axially around the center hole in which the needle roller bearing 21 is fitted. In the external gear 4 of the present embodiment, six carrier pin holes 4h are arranged on the same circumference at regular intervals in the circumferential direction (the phases are shifted by 60 degrees). In addition, in the reduction gear 1 of this embodiment, one external gear 4 is attached to the input shaft 2 .

The internal gear 5 is a substantially cylindrical gear located on the outer periphery of the external gear 4 . As shown in FIGS. 1 and 2, the internal gear 5 includes a plurality of outer pins 50 that internally mesh with the outer teeth 4t and rotate while being bent, and outer pin holders that rotatably hold the outer pins 50. 51. The outer pin 50 is a cylindrical pin member that is thin enough to bend under the force of the external gear 4 during rotation. do. The number of outer pins 50 (the number of inner teeth) of the present embodiment is a value obtained by adding 1 to the number of outer teeth 4 t of the external gear 4 . The difference between the number of outer pins 50 (the number of inner teeth) and the number of teeth of the external gear 4 can be a natural number other than 1 depending on the design of the speed reduction ratio.

As shown in FIG. 3, the outer pin holder 51 has a cylindrical outer shape and a cylindrical inner surface. The inner surface of the outer pin holder 51 is formed with a substantially semicircular pin groove 51a recessed in the axial direction and a recessed groove 51b recessed across the pin groove 51a. The pin grooves 51 a are grooves for holding the outer pins 50 , are provided in the same number as the outer pins 50 , and have a curvature that substantially matches the curvature of the outer pins 50 . On the other hand, the concave groove 51b is a groove for holding a lubricant (for example, grease or oil), and is formed along the entire circumference of the inner surface of the outer pin holder 51. As shown in FIG. The outer pin holder 51 of this embodiment is made of a material softer than the material of the outer pin 50 . For example, the outer pin holder 51 is made of an aluminum-based material (aluminum alloy) or a soft material such as resin, and the outer pin 50 is made of an iron-based material.

Here, the shape of the inner surface of the outer pin holder 51 will be described in detail with reference to FIGS. 5 and 6 as well. 5 and 6 are sectional views of the outer pin holder 51, the outer pin 50, and the external gear 4 cut along the axial center of the outer pin 50 meshing with the external teeth 4t of the external gear 4. FIG. be. 5 and 6 are enlarged views of the periphery of the edge of the recessed groove 51b, and the central bottom view of FIG. The lower center figure is an axis-perpendicular cross-sectional view cut along the concave groove 51b other than the edge. The term "edge" used herein means a corner formed by the bottom surface of the pin groove 51a and the side surface of the groove 51b, and two edges are provided for each pin groove 51a. As shown in FIG. 3, each edge has a semicircular shape when viewed from the axial direction.

As shown in FIGS. 5 and 6, the edge of the recessed groove 51b of the outer pin holder 51 is provided with a rolling surface 51d that comes into surface contact with the outer peripheral surface of the outer pin 50 while the outer pin 50 is bent and rotated. . When the speed reducer 1 is in a driven state, the outer pin 50 receives force (lateral pressure) from the external gear 4 as indicated by the white arrow in FIG. As a result, the outer pin 50 rotates while bending outward in the radial direction of the internal gear 5, and rolls and slides in the pin groove 51a as shown in the cross-sectional view taken along the line BB. The rolling surface 51d has a shape that makes surface contact with the outer peripheral surface of the outer pin 50 in this rotating state. That is, the rolling surface 51d is formed in a shape obtained by chamfering the edge of the recessed groove 51b, as shown enlarged in FIG.

In the speed reducer 1 of the present embodiment, the rolling surface 51d is ground by sliding contact when the outer pin 50 rotates. Since the outer pin 50 of this embodiment is made of a harder material than the outer pin holder 51, when the outer pin 50 rotates in a flexed state and keeps sliding contact with the edge, the edge is pushed by the outer pin 50. The outer pin 50 is cut by a predetermined amount in a substantially circular arc shape, and eventually becomes a shape having a cylindricity and a clearance that allow the outer pin 50 to smoothly rotate on the rolling contact surface 51d. The edge is dulled at the timing when the outer peripheral surface of the outer pin 50 and the predetermined surface contact state are established. The outer pin 50 rolls most easily when the wear of the edge is saturated.

Further, in the outer pin holder 51 of this embodiment, there are portions with different inner diameters (radii) within one pin groove 51a. Specifically, the inner diameter at the position of the rolling surface 51d is larger than the inner diameter at positions other than the rolling surface 51d. Furthermore, the inner diameter of the pin groove 51a is set equal to the outer diameter of the outer pin 50 at the position of the rolling surface 51d. As a result, when the speed reducer 1 is stopped, the clearance between the outer peripheral surface of the outer pin 50 and the inner surface of the pin groove 51a is substantially zero, as shown in the cross-sectional view perpendicular to the axis in FIG. On the other hand, as shown in the cross-sectional view perpendicular to the axis in FIG. 5, the inner diameter at the position of the rolling surface 51d is larger than the outer diameter of the outer pin 50. Therefore, when the speed reducer 1 is in a driven state, the clearance between the outer peripheral surface of the outer pin 50 and the inner surface of the pin groove 51a becomes large, and play occurs, so that the outer pin 50 can rotate with low loss.

As shown in FIGS. 2 and 3, the outer pin holder 51 is provided with a plurality of through holes 51c in the circumferential direction, through which fastening members 73 for fastening the internal gear 5 and the case 7 are inserted. That is, the outer pin holder 51 of the internal gear 5 is fixed to the case 7 and does not rotate. Therefore, although the external gear 4 meshing with the internal gear 5 tries to rotate with the eccentric rotation of the input shaft 2, the position of the external pin 50 meshing with the external tooth 4t does not move. The reaction force causes the input shaft 2 to swing in a direction opposite to the direction of rotation. Specifically, when the input shaft 2 rotates once, the external gear 4 shifts (rotates) in the opposite direction from the internal gear 5 by one tooth. That is, the rotation of the input shaft 2 is decelerated by the reciprocal of the number of teeth of the external gear 4 (1/number of teeth), and the external gear 4 rotates in the reverse direction.

The case 7 is a member that accommodates elements other than the output shaft 3 . As shown in FIGS. 1 and 4, the case 7 of the present embodiment is arranged on the first case portion 71 arranged on the motor 10 side (right side in the figure) and on the output shaft 3 side (left side in the figure). The second case portion 72 is connected with a plurality of fastening members 73 . Each of the first case portion 71 and the second case portion 72 has a cylindrical shape with a bottom, and has a circular opening 7a in the bottom portion thereof. The two case parts 71 and 72 are attached so as to sandwich the outer pin holder 51 from both sides in the axial direction.

The case 7 of this embodiment has only a very small clearance between the axial end faces of the outer pin holder 51 and the end face of the outer pin 50, which allows the outer pin 50 to rotate smoothly without side slippage. Regulate so that the directional positions do not deviate from each other. Further, as described above, the axial position of the external gear 4 is regulated by the washer 22 . That is, in the speed reducer 1 of the present embodiment, the case 7 and the washer 22 have a function as a guide portion for maintaining a constant axial positional relationship between the external gear 4, the outer pin holder 51, and the outer pin 50. . As a result, the outer peripheral surface of the outer pin 50 and the rolling contact surface 51d are kept in a predetermined contact state in the driving state.

The carrier 6 is a member that extracts only the rotation component of the external gear 4 described above and transmits it to the output shaft 3 . As shown in FIG. 1 , the carrier 6 has carrier pins 60 that rotate inscribed in the carrier pin holes 4 h of the external gear 4 , and support portions 61 that support the carrier pins 60 . The carrier pin 60 is a columnar pin member, is arranged so that its axial direction is parallel to the rotation center C, and has a function of taking out only the rotation component of the external gear 4 . As shown in FIG. 2, in the carrier 6 of this embodiment, six carrier pins 60 are provided, and needle roller bearings 62 are mounted on each carrier pin 60 . That is, in the present embodiment, the carrier pin 60 contacts the inner peripheral surface of the carrier pin hole 4h via the needle roller bearing 62, thereby suppressing sliding loss between the carrier pin 60 and the support portion 61. , the carrier pin 60 rotates the support portion 61 (carrier 6).

As shown in FIG. 1 , the support portion 61 is a portion that supports one end of each carrier pin 60 and connects all the carrier pins 60 . The carrier pin 60 of the present embodiment is supported by the support portion 61 so as not to rotate about its axis and relatively unrotatable, and the carrier pin 60 and the support portion 61 of the carrier 6 rotate integrally. The flange portion 3 b of the output shaft 3 is fixed to the support portion 61 . As a result, the output shaft 3 and the carrier 6 rotate together. One end of each carrier pin 60 may be configured to be relatively rotatably supported by the support portion 61 via a bearing, a bush, or the like.

Further, the carrier 6 of this embodiment has two support portions 61 that support both ends of the carrier pin 60 respectively. The two support portions 61 are opposed to each other with the external gear 4 interposed therebetween, and support the carrier pins 60 on both sides. Each support portion 61 is fixed to the outer ring of the ball bearing 9 that supports the input shaft 2 and is fixed to the inner ring of the outer ball bearing 8 that supports the carrier 6 so as to be rotatable. In addition, the outer ring of the ball bearing 8 is fixed to the case 7 .

That is, the radially outer ball bearing 8 rotatably supports the support portion 61 with respect to the case 7 , and the radially inner ball bearing 9 rotatably supports the input shaft 2 with respect to the carrier 6 . In the speed reducer 1 of the present embodiment, two ball bearings 8 and 9 are provided and arranged at the same axial position. The term "same axial position" as used herein does not only mean that the axial positions of the end surfaces of the two ball bearings 8 and 9 are completely aligned, but also that the balls of the ball bearings 8 and 9 Includes overlapping positions. As a result, the axial dimension of the case 7 is reduced, and the size reduction of the speed reducer 1 is achieved.

[2. Production method]
FIG. 7 is a flow chart showing an example of a method for manufacturing the speed reducer 1 described above. Here, the method of forming the inner surface shape of the outer pin holder 51 will be mainly described. It is assumed that each component such as the input shaft 2 and the output shaft 3 is prepared in advance.

First, a plurality of pin grooves 51a for holding the outer pins 50 in the axial direction are formed on the cylindrical inner surface of the component (cylindrical component with a constant thickness in the axial direction) that will become the outer pin holder 51 shown in FIG. form (step S1). In step S1, the inner surface of the pin groove 51a is formed into a semi-cylindrical surface having an inner diameter equal to the outer diameter of the outer pin 50 and constant in the axial direction. The number of pin grooves 51 a is the same as the number of teeth of the internal gear 5 , and the arrangement thereof is set at equal intervals in the circumferential direction of the inner surface of the outer pin holder 51 . A small space is provided between two pin grooves 51a adjacent in the circumferential direction.

Next, the concave groove 51b is formed on the inner surface of the component that will become the outer pin holder 51 (step S2). The recessed groove 51b extends over the entire circumference of the inner surface so as to cross the axially intermediate portion of the pin groove 51a, and is recessed in a substantially rectangular shape with a depth dimension larger than that of the pin groove 51a. At this stage, the corner (edge) formed by the bottom surface of the pin groove 51a and the side surface of the groove 51b is a right angle. Note that steps S1 and S2 are called a groove forming step.

After the groove forming process, the input shaft 2, the output shaft 3, the external gear 4, the internal gear 5, the carrier 6, and the case 7 are assembled (step S3). Then, the input shaft 2 is rotated (the speed reducer 1 is driven), and the outer pin 50 rotates while bending toward the inside of the groove 51b, thereby making sliding contact with the edge of the groove 51b, and rolling the rolling surface 51d. is formed (cut) (step S4). In other words, when the edge of the outer pin 50 is worn away and the amount of wear reaches a certain amount and it becomes impossible to grind it any more, the rolling surface 51d is formed. This step S4 is called a rolling surface forming step.

In the rolling surface forming step, the edge of the concave groove 51b is ground to form the rolling surface 51d, so the inner diameter of the pin groove 51a becomes large at the position of the rolling surface 51d. In the rolling surface forming step of the present embodiment, the rolling surface 51d is formed such that the inner diameter at the position of the rolling surface 51d is larger than the inner diameter at positions other than the rolling surface 51d. Thus, the inner surface shape of the outer pin holder 51 is formed through the groove forming process and the rolling surface forming process.

[3. effect]
(1) According to the speed reducer 1 described above, since the edge of the groove 51b is provided with the rolling surface 51d that comes into surface contact when the outer pin 50 bends and rotates, the outer pin 50 can easily roll. can be done. As a result, the outer pin 50 forming the inner teeth can be rotated with low loss, so that noise reduction and efficiency improvement can be achieved.

(2) In the speed reducer 1 described above, since there are locations with different inner diameters in one pin groove 51a, different clearances can be used depending on whether the speed reducer 1 is driven or stopped. That is, during driving, the outer pin 50 rotates while bending on the rolling surface 51d having a large clearance between the outer peripheral surface of the outer pin 50 and the inner surface of the pin groove 51a. A large backlash can be ensured, and the rotation loss of the outer pin 50 can be reduced. On the other hand, when the speed reducer 1 is stopped, the outer pin 50 does not bend and the clearance becomes smaller, so that the backlash between the outer tooth 4t and the inner tooth (outer pin 50) can be reduced.

(3) In the speed reducer 1 described above, the outer pin holder 51 is made of a material softer than the outer pin 50, and the rolling surface 51d is formed by the outer pin 50 itself due to sliding contact during rotation of the outer pin 50. As a result, the outer pin 50 can be put in a state where it is most likely to roll. For this reason, the outer pin 50 can be rotated with less loss, so that low noise and high efficiency can be achieved. Furthermore, in order to achieve low noise, high-precision machining is required to improve the cylindricity of the pin grooves 51a.

(4) For example, if the outer pin holder 51 is made of an aluminum-based material and the outer pin 50 is made of an iron-based material, the flexing, rolling, and sliding motion of the outer pin 50 ensures that the outer pin holder 51 can be formed with a rolling surface 51d.

(5) In addition, the above-described speed reducer 1 is provided with the case 7 and the washer 22 as a guide portion for maintaining a constant axial positional relationship between the external gear 4, the outer pin holder 51, and the outer pin 50. , the position of the force acting on the outer pin 50 from the external gear 4 can be made constant. As a result, the amount of bending (the manner of bending) of the outer pin 50 can be made constant, and the outer pin 50 can always rotate on the rolling surface 51d, so that low noise and high efficiency can be stably achieved.

(6) Since the above-described manufacturing method includes the groove forming step and the rolling surface forming step, the rolling surface 51d can be formed on the outer pin 50 itself, and the outer pin 50 is in a state where it can roll most easily. can be As a result, the outer pin 50 can be rotated with less loss without requiring high-precision machining, thereby achieving low noise, high efficiency, and low cost.

(7) Furthermore, according to the manufacturing method described above, portions having different inner diameters can be provided in one pin groove 51a, and different clearance portions can be used depending on whether the speed reducer 1 is driven or stopped. As a result, a large backlash between the outer teeth 4t and the inner teeth (outer pins 50) can be ensured during driving, and the rotation loss of the outer pins 50 can be reduced. ) can be reduced.

(8) In addition, according to the motor unit composed of the speed reducer 1 and the motor 10 described above, the outer pin 50 can be rotated with low loss, so that the motor unit as a whole can achieve low noise and high efficiency. can be planned.

[4. others]
The speed reducer 1 and the motor unit described above are examples, and are not limited to those described above. In the speed reducer 1 described above, the rolling surface 51d is formed by the outer pin 50 itself, but the rolling surface 51d may be formed by machining. In this case, the material of the outer pin holder 51 and the outer pin 50 is not particularly limited, and for example, the outer pin holder 51 and the outer pin 50 may be made of the same material. At least the edge of the recessed groove 51b of the outer pin holder 51 has a rolling surface formed in a shape that is in surface contact with the outer peripheral surface of the outer pin 50 when the outer pin 50 bends and rotates (driving state of the speed reducer 1). If 51d is provided, the outer pin 50 can be rotated with low loss, so that low noise and high efficiency can be achieved.

The pin groove 51a is formed with an inner diameter equal to the outer diameter of the outer pin 50 at a position other than the rolling surface 51d, but may be formed with an inner diameter slightly larger than the outer diameter of the outer pin 50. . The pin groove 51a may have at least a shape and size that allow the outer pin 50 to rotate within the pin groove 51a. The number of outer pins 50 forming inner teeth and the number of pin grooves 51a for supporting them are not limited to those described above. Moreover, although one external gear 4 is provided in the speed reducer 1 described above, the number of the external gears 4 may be two or more. Further, in the speed reducer 1 described above, the case 7 and the washer 22 have a function as a guide portion. good too.

The configurations of the input shaft 2, the output shaft 3, and the case 7 are not limited to those described above. For example, the input shaft 2 may be extended so as to protrude outside the first case portion 71, or the cylindrical portion 2a and the eccentric portion 2b may be separately provided and then joined together. good too. Further, although the needle roller bearing 21 is fixed to the eccentric portion 2b of the input shaft 2, the support structure of the input shaft 2 is not particularly limited. The fixing structure between the output shaft 3 and the carrier 6 is not particularly limited, and the case 7 may be integrated.

In addition, the carrier 6 is provided with two support portions 61 that respectively support both ends of the carrier pin 60 , but only one support portion 61 is provided so as to support one end of the carrier pin 60 . may have been In this case, the other end of the carrier pin 60 has a cantilever support structure in which only one end is supported. Moreover, the needle roller bearing 62 may not be attached to the carrier pin 60 . Although the two ball bearings 8 and 9 are arranged at the same axial position, the axial positions of these bearings 8 and 9 may be different. Moreover, the bearings 8 and 9 may be rolling bearings, and the type thereof is not limited to ball bearings.

1 Reducer (cycloidal reducer)
2 input shaft 4 external gear 4t external gear 5 internal gear 6 carrier 7 case (guide portion)
10 motor 11 motor rotating shaft 22 washer (guide part)
50 outer pin 51 outer pin holder (holder)
51a Pin groove 51b Concave groove 51d Rolling surface C Rotation center

Claims (7)

an external gear mounted eccentrically rotatably with respect to the rotation center of the input shaft;
an internal gear having a plurality of outer pins that internally mesh with the external teeth of the external gear and rotate while bending; and a holder that has a cylindrical inner surface and rotatably holds each of the outer pins;
A carrier that takes out only the rotation component of the external gear,
The holder has a plurality of pin grooves axially recessed on the inner surface for holding the outer pins, and a recessed groove recessed over the entire circumference of the inner surface so as to traverse the pin grooves. has
An edge of the groove is provided with a rolling surface that comes into surface contact with an outer peripheral surface of the outer pin when the outer pin bends and rotates ,
The pin groove has an inner diameter larger than the outer diameter of the outer pin at the position of the rolling surface, and the inner diameter at a position other than the rolling surface is equal to the outer diameter of the outer pin. ing
A cycloid reducer characterized by: The inner surface of the pin groove other than the rolling surface is formed into a semi-cylindrical surface having an inner diameter equal to the outer diameter of the outer pin and constant in the axial direction.
The cycloid reducer according to claim 1, characterized by: The holder is made of a material softer than the material of the outer pin,
3. The cycloid reducer according to claim 1, wherein said rolling surface is formed by sliding contact during rotation of said outer pin. The outer pin is made of a ferrous material,
4. The cycloid reducer according to claim 3, wherein said holder is made of an aluminum-based material. The cycloid reducer according to any one of claims 1 to 4, further comprising a guide portion that maintains a constant axial positional relationship between the external gear, the holder, and the outer pin. An external gear mounted to be eccentrically rotatable with respect to the rotation center of the input shaft, a plurality of outer pins that internally mesh with the external teeth of the external gear and rotate while bending, and each of the outer pins are rotatable. A method for manufacturing a cycloid reduction gear comprising: an internal gear having a holder held in the
A plurality of pin grooves extending in the axial direction for holding the outer pins, and grooves extending along the entire circumference of the inner surface so as to traverse the pin grooves are formed on the cylindrical inner surface of the component that serves as the holder. a recessed groove forming step;
a rolling surface forming step of rotating the input shaft so that the outer pin rotates while bending toward the inside of the groove, thereby slidingly contacting the edge of the groove to form a rolling surface; with
In the groove forming step, the inner surface of the pin groove is formed into a semi-cylindrical surface having an inner diameter equal to the outer diameter of the outer pin and constant in the axial direction,
In the rolling surface forming step, the rolling surface is ground so that the inner diameter at the position of the rolling surface is larger than the inner diameter at positions other than the rolling surface.
A method for manufacturing a cycloid reducer, characterized by: A cycloid reducer according to any one of claims 1 to 5;
and a motor having a motor rotation shaft connected to the input shaft of the cycloid reducer.

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