JP2021025590A - Planetary gear speed reduction device, geared motor, and driving device - Google Patents

Abstract

To provide a planetary gear speed reduction device capable of achieving miniaturization of the entire device.SOLUTION: A planetary gear speed reduction device 22 includes: a pinion 25 connected to a motor shaft 24; a planetary gear 61 made of resin; a carrier 71 rotatable coaxially with the pinion 25; and an internal gear 232 for holding the planetary gear 61 so as to revolve around the pinion 25. The planetary gear 61 rotates according to the rotation of the pinion 25 being engaged with the pinion 25. The carrier 71 rotatably holds the planetary gear 61. The carrier 71 has a solid shaft part 712 extending coaxially with the planetary gear 61. On an upper side of the planetary gear 61, a bearing recessed part 612 is formed for receiving the solid shaft part 712 of the carrier 71. On a lower side of the planetary gear 61, a gate part 614 protruding downward is formed.SELECTED DRAWING: Figure 3

Description

The present invention relates to a planetary gear speed reducer, a geared motor, and a drive device, and more particularly to a planetary gear speed reducer including a resin planetary gear.

In a geared motor incorporated in a small drive, a planetary gear speed reducer may be used to slow down the rotation of the motor to obtain a large torque. In such a planetary gear speed reducer, since it is necessary to make the planetary gear incorporated therein small, resin planetary gears that can be easily manufactured by injection molding or the like are often used (see, for example, Patent Document 1). ..

In this injection molding, a heat-melted resin material is injected into a mold, the resin material is cooled and solidified, and then the molded product is taken out from the mold. At this time, the gate portion remains in the molded product due to the resin injection port (gate) into the molded product. In the planetary gear speed reducer disclosed in Patent Document 1, the length of the planetary gear speed reducer in the axial direction is obtained by accommodating the gate portion formed in the planetary gear inside the recess formed in the shaft portion of the carrier. Is shortened to reduce the size.

However, in the planetary gear speed reducer disclosed in Patent Document 1, since a recess is formed in the shaft portion of the carrier, the thickness of the shaft portion of the carrier in the radial direction is reduced. Therefore, in order to maintain the strength of the shaft portion of the carrier, the diameter of the shaft portion of the carrier must be increased to some extent, and there is a limit to reducing the carrier. As a result, it becomes difficult to further reduce the size of the entire planetary gear speed reducer.

Japanese Unexamined Patent Publication No. 2016-121738

The present invention has been made in view of such problems of the prior art, and a first object of the present invention is to provide a planetary gear reduction device capable of realizing miniaturization of the entire device.

A second object of the present invention is to provide a small geared motor.

Furthermore, a third object of the present invention is to provide a small drive device.

According to the first aspect of the present invention, there is provided a planetary gear reduction device capable of realizing miniaturization of the entire device. This planetary gear speed reducer is used to slow down the rotation of the input shaft and transmit it to the output shaft. The planetary gear speed reducer includes a first sun gear connected to the input shaft, a first planetary gear made of resin, a first carrier that can rotate coaxially with the first sun gear, and the above. It includes an internal gear that revolves around the first sun gear and holds the first planetary gear. The first planetary gear meshes with the first sun gear and rotates with the rotation of the first sun gear. The first carrier rotatably holds the first planetary gear. The first carrier has a first solid shaft portion that extends coaxially with the first planetary gear. On the output shaft side of the first planetary gear, a first bearing recess for receiving the first solid shaft portion of the first carrier is formed. On the input shaft side of the first planetary gear, a first gate portion protruding toward the input shaft side is formed.

According to such a configuration, since the first gate portion of the first planetary gear made of resin is formed on the input shaft side of the first planetary gear, a recess is formed in the shaft portion of the first carrier. In the first bearing recess of the first planetary gear, the first solid shaft portion of the first carrier can be received. Therefore, even if the shaft portion of the first carrier is thinned, the strength of the shaft portion of the first carrier is maintained. As a result, the size of the first carrier can be reduced, and eventually the entire planetary gear speed reducer can be reduced in size.

The first gate portion of the first planetary gear is preferably located on the central axis of the first planetary gear. In this case, the heat shrinkage during molding of the first planetary gear can be made uniform in the entire first planetary gear, and the dimensional accuracy of the first planetary gear can be improved.

The planetary gear speed reducer may further include a flange having an annular wall that contacts a part of the first contact surface on the input shaft side of the first planetary gear. In this case, the first gate portion of the first planetary gear for moving the first gate portion of the first planetary gear between the first planetary gear and the flange is inside the annular wall of the flange in the radial direction. The moving space of the gate portion of the above may be specified.

According to such a configuration, when the first planetary gear rotates, the first gate portion of the first planetary gear can move in the moving space of the first gate portion without interfering with the flange. It will be possible. Further, since the first planetary gear rotates while only a part of the first contact surface of the first planetary gear is in sliding contact with the annular wall of the flange, the contact between the first planetary gear and the flange The area becomes smaller. Therefore, it is possible to reduce the frictional resistance generated when the first planetary gear rotates.

The first carrier may have a second sun gear that is arranged coaxially with the first sun gear. In this case, the planetary gear speed reducer may further include a second planetary gear made of resin and a second carrier that can rotate coaxially with the second sun gear. The second planetary gear may mesh with the second sun gear and rotate with the rotation of the second sun gear. The second carrier may rotatably hold the second planetary gear. The internal gear may revolve around the second planetary gear around the second sun gear. The second carrier may have a second solid shaft portion that extends coaxially with the second planetary gear. A second bearing recess may be formed on the output shaft side of the second planetary gear to receive the second solid shaft portion of the second carrier. A second gate portion protruding toward the input shaft side may be formed on the input shaft side of the second planetary gear.

According to such a configuration, since the second gate portion of the second planetary gear made of resin is formed on the input shaft side of the second planetary gear, a recess is formed in the shaft portion of the second carrier. The second bearing recess of the second planetary gear can receive the second solid shaft portion of the second carrier. Therefore, even if the shaft portion of the second carrier is thinned, the strength of the shaft portion of the second carrier is maintained. As a result, the size of the second carrier can be reduced, and as a result, the size of the entire planetary gear speed reducer can be reduced.

The second gate portion of the second planetary gear is preferably located on the central axis of the second planetary gear. In this case, the heat shrinkage during molding of the second planetary gear can be made uniform in the entire second planetary gear, and the dimensional accuracy of the second planetary gear can be improved.

The first carrier may have a contact portion that contacts a part of the second contact surface on the input shaft side of the second planetary gear. In this case, on the radial outer side of the contact portion of the first carrier, the second gate portion of the second planetary gear between the second planetary gear and the first carrier. A second gate portion moving space for moving the may be defined.

According to such a configuration, when the second planetary gear rotates, the second gate portion of the second planetary gear moves in the moving space of the second gate portion without interfering with the first carrier. It becomes possible to do. Further, since only a part of the second contact surface of the second planetary gear is in sliding contact with the contact portion of the first carrier, the second planetary gear rotates, so that the second planetary gear and the second planetary gear The contact area with the first carrier becomes smaller. Therefore, the frictional resistance generated when the second planetary gear rotates can be reduced.

According to the second aspect of the present invention, a small geared motor is provided. This geared motor includes the above-mentioned planetary gear reduction device and a motor having a motor shaft connected to the above-mentioned first sun gear of the above-mentioned planetary gear reduction device.

According to a third aspect of the present invention, a small drive device is provided. This drive device is used to move the object to be driven along the axial direction. The drive device includes the geared motor described above, a frame to which the geared motor is mounted, a reed screw extending in the axial direction and rotated by the geared motor, and a movable member having a nut portion screwed to the lead screw.

According to the present invention, since the first gate portion of the first planetary gear made of resin is formed on the input shaft side of the first planetary gear, it is necessary to form a recess in the shaft portion of the first carrier. In the first bearing recess of the first planetary gear, the first solid shaft portion of the first carrier can be received. Therefore, even if the shaft portion of the first carrier is thinned, the strength of the shaft portion of the first carrier is maintained. As a result, the size of the first carrier can be reduced, and eventually the entire planetary gear speed reducer can be reduced in size.

FIG. 1 is a perspective view showing a driving device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the geared motor in the drive device shown in FIG. 1 as viewed from above. FIG. 3 is an exploded perspective view of the geared motor shown in FIG. 2 as viewed from below. FIG. 4 is a partial cross-sectional view of the geared motor shown in FIG. 1 when cut along a plane including a motor shaft and one central shaft of a planetary gear.

Hereinafter, embodiments of the drive device including the planetary gear reduction device according to the present invention will be described in detail with reference to FIGS. 1 to 4. In FIGS. 1 to 4, the same or corresponding components are designated by the same reference numerals, and duplicate description will be omitted. Further, in FIGS. 1 to 4, the scale and dimensions of each component may be exaggerated or some components may be omitted.

FIG. 1 is a perspective view showing a drive device 1 according to an embodiment of the present invention. The drive device 1 in the present embodiment moves a drive object such as a lens or a camera as necessary in an electronic device such as a laser irradiation type disk device or a smartphone, but its use is limited to these. is not it. In the present embodiment, for convenience, the + Z direction in FIG. 1 is referred to as "up" or "upward", and the −Z direction is referred to as "down" or "downward".

As shown in FIG. 1, the drive device 1 includes a frame 10 attached to an electronic device main body (not shown) such as a smartphone main body, a geared motor 20 attached to the frame 10, and a lead extending in the Z direction (axial direction). It has a screw 30, a movable member 40 that engages with the lead screw 30, and a guide shaft 50 that guides the movement of the movable member 40 along the Z direction.

The frame 10 has an upper flange portion 11, a lower flange portion 12, and a fixing portion 13 in which a screw hole 13A through which a fixing screw is inserted is formed. The frame 10 is fixed to the electronic device main body by inserting a screw (not shown) into the screw hole 13A of the fixing portion 13 and screwing the screw into the electronic device main body.

The lead screw 30 is attached to the upper flange portion 11 and the lower flange portion 12 of the frame 10 via the upper bearing 31 and the lower bearing 32, respectively, and is rotatably supported by the frame 10. The lead screw 30 is connected to the output shaft of the geared motor 20 and is rotated by the operation of the geared motor 20. Further, the guide shaft 50 extends in the Z direction between the upper flange portion 11 and the lower flange portion 12 of the frame 10. That is, the guide shaft 50 and the lead screw 30 extend in parallel with each other.

The movable member 40 has a nut portion 41 in which a screw groove that engages with the lead screw 30 is formed, and a sliding portion 42 in which a shaft hole through which the guide shaft 50 is inserted is formed. The sliding portion 42 is adapted to slide in the Z direction on the guide shaft 50 while being guided by the guide shaft 50 inserted into the shaft hole.

FIG. 2 is an exploded perspective view of the geared motor 20 as viewed from above, and FIG. 3 is an exploded perspective view of the geared motor 20 shown in FIG. 2 as viewed from below. As shown in FIGS. 2 and 3, the geared motor 20 includes, for example, a motor 21 configured by a stepping motor and a planetary gear speed reducer 22 arranged between the motor 21 and the reed screw 30. The motor 21 has a motor shaft 24 extending upward from the center of the upper surface thereof, and the planetary gear speed reducer 22 decelerates the rotation of the motor shaft 24 as an input shaft and transmits the rotation to the lead screw 30 as an output shaft. ..

The planetary gear speed reducer 22 has a gear case 23 arranged above the motor 21. The gear case 23 has a rectangular plate shape located between the bearing holding portion 231 that holds the lower bearing 32, the cylindrical portion 233 having the internal gear 232 on the inner peripheral surface, and the bearing holding portion 231 and the cylindrical portion 233. Includes part 234 and. In the present embodiment, two upper and lower planetary gear mechanisms are housed inside the gear case 23.

As shown in FIGS. 2 and 3, the planetary gear speed reducer 22 has a flange 80 attached to the end face of the motor 21. A through hole 81 is formed in the central portion of the flange 80, and the motor shaft 24 of the motor 21 penetrates the center of the through hole 81. Further, the planetary gear speed reducer 22 includes a pinion 25 (first sun gear) fixed to the motor shaft 24 and rotating together with the motor shaft 24, and three planetary gears arranged around the pinion 25 and meshing with the pinion 25. It is arranged around a 61 (first planetary gear), a carrier 71 (first carrier) that rotatably holds the planetary gear 61, and a pinion 713 (second sun gear) formed on the carrier 71. It includes three planetary gears 62 (second planetary gears) that mesh with the pinion 713 and a carrier 72 (second carrier) that rotatably holds the planetary gears 62. FIG. 4 is a partial cross-sectional view when the geared motor 20 is cut on a plane including the motor shaft 24 and one central shaft of the planetary gear 61.

The carrier 71 has a carrier main body 711 and three solid shaft portions 712 (first solid shaft portions) extending downward from the carrier main body 711. The pinion 713 described above is arranged coaxially with the motor shaft 24 on the upper surface of the carrier main body 711. As shown in FIG. 2, a bearing recess 612 (first bearing recess) for receiving the solid shaft portion 712 of the carrier 71 is formed on the upper side of the planetary gear 61. By inserting the solid shaft portion 712 of the carrier 71 into the bearing recess 612, the three planetary gears 61 are rotatably supported with respect to the carrier 71.

The carrier 72 is a shaft connection in which a carrier main body 721, three solid shaft portions 722 (second solid shaft portions) extending downward from the carrier main body 721, and a lower end portion of a lead screw 30 as an output shaft are connected. It has a part 723 and a part 723. As shown in FIG. 2, a bearing recess 622 (second bearing recess) for receiving the solid shaft portion 722 of the carrier 72 is formed on the upper side of the planetary gear 62. By inserting the solid shaft portion 722 of the carrier 72 into the bearing recess 622, the three planetary gears 62 are rotatably held with respect to the carrier 72.

In such a configuration, the first stage (lower stage) planetary gear mechanism includes a pinion 25 connected to the motor shaft 24, three planetary gears 61 arranged around the pinion 25, and a cylindrical portion of the gear case 23. It is composed of an internal gear 232 formed in 233 and a carrier 71 that rotatably holds the planetary gear 61. The second stage (upper stage) planetary gear mechanism is formed on the pinion 713 formed on the carrier 71, the three planetary gears 62 arranged around the pinion 713, and the cylindrical portion 233 of the gear case 23. It is composed of an internal gear 232 and a carrier 72 that rotatably holds the planetary gear 62.

According to such a configuration, when the motor shaft 24 is rotated by the drive of the motor 21, the pinion 25 is rotated. Therefore, the three planetary gears 61 meshing with the pinion 25 are centered on the solid shaft portion 712 of the carrier 71. Rotate (rotate) as. Further, since each of the planetary gears 61 meshes with the internal gear 232 formed in the gear case 23 on the opposite side of the pinion 25, it revolves around the pinion 25 along the internal gear 232. Then, the carrier 71 rotates around the central axis as the planetary gears 61 revolve.

When the carrier 71 rotates, the pinion 713 also rotates, so that the three planetary gears 62 meshing with the pinion 713 rotate (rotate) around the solid shaft portion 722 of the carrier 72. Further, since each of the planetary gears 62 meshes with the internal gear 232 formed in the gear case 23 on the opposite side of the pinion 713, it revolves around the pinion 713 along the internal gear 232. Then, along with the revolution of these planetary gears 62, the carrier 72 rotates around the central axis. As a result, the reed screw 30 connected to the shaft connecting portion 723 of the carrier 72 rotates. As described above, since the planetary gear reduction device 22 in the present embodiment includes the two-stage planetary gear mechanism, the rotation of the motor shaft 24 of the motor 21 is reduced by a large reduction ratio, and the torque of the lead screw 30 is increased. can do.

The planetary gear 61 and the planetary gear 62 in the present embodiment are made of resin, and are manufactured by, for example, injection molding. As shown in FIG. 3, a gate portion 614 (first gate portion) generated during molding is formed on the lower side of the planetary gear 61 so as to project downward from the lower surface 615 of the planetary gear 61. As described above, in the present embodiment, since the gate portion 614 of the planetary gear 61 made of resin is formed so as to project below the planetary gear 61, the shaft of the carrier 71 is formed like a conventional planetary gear reduction device. It is not necessary to form a recess in the portion, and the bearing recess 612 of the planetary gear 61 can receive the solid shaft portion 712 of the carrier 71. Therefore, even if the shaft portion of the carrier 71 is thinned, the strength of the shaft portion of the carrier 71 is maintained. As a result, the size of the carrier 71 can be reduced, and the size of the planetary gear reduction device 22 as a whole can be reduced. The gate portion 614 of the planetary gear 61 described above is preferably located on the central axis of the planetary gear 61. If the gate portion 614 is arranged on the central axis of the planetary gear 61, the heat shrinkage during molding can be made uniform in the entire planetary gear 61, and the dimensional accuracy of the planetary gear 61 can be improved.

Similarly, on the lower side of the planetary gear 62, a gate portion 624 (second gate portion) generated during molding is formed so as to project downward from the lower surface 625 of the planetary gear 62. As described above, in the present embodiment, since the gate portion 624 of the planetary gear 62 made of resin is formed so as to project below the planetary gear 62, the shaft of the carrier 72 is formed like a conventional planetary gear reduction device. It is not necessary to form a recess in the portion, and the bearing recess 622 of the planetary gear 62 can receive the solid shaft portion 722 of the carrier 72. Therefore, even if the shaft portion of the carrier 72 is thinned, the strength of the shaft portion of the carrier 72 is maintained. As a result, the size of the carrier 72 can be reduced, and eventually the entire planetary gear speed reducer 22 can be reduced in size. The gate portion 624 of the planetary gear 62 described above is preferably located on the central axis of the planetary gear 62. If the gate portion 624 is arranged on the central axis of the planetary gear 62, the heat shrinkage during molding can be made uniform in the entire planetary gear 62, and the dimensional accuracy of the planetary gear 62 can be improved.

As shown in FIGS. 2 and 3, an annular wall 85 projecting upward is formed in the vicinity of the outer edge of the flange 80. As shown in FIG. 4, the annular wall 85 of the flange 80 comes into contact with a part of the lower surface 615 (first contact surface) of each planetary gear 61, and when the planetary gear 61 rotates A part of the lower surface 615 of the planetary gear 61 slides on the annular wall 85 of the flange 80. A space S1 is formed between the planetary gear 61 and the flange 80 inside the annular wall 85 of the flange 80 in the radial direction, and the gate portion 614 of the planetary gear 61 is housed in this space S1. Therefore, when the planetary gear 61 rotates, the gate portion 614 of the planetary gear 61 can move in the space S1 without interfering with the flange 80. That is, the space S1 inside the annular wall 85 of the flange 80 in the radial direction is a first gate portion moving space for moving the gate portion 614 of the planetary gear 61 between the planetary gear 61 and the flange 80. ..

As described above, in the present embodiment, the gate portion 614 of the planetary gear 61 is configured to move in the space S1 between the planetary gear 61 and the flange 80, so that when the planetary gear 61 rotates, it moves. The gate portion 614 of the planetary gear 61 can move in the space S1 without interfering with the flange 80. Further, when the planetary gear 61 rotates, only a part of the lower surface 615 of the planetary gear 61 is in sliding contact with the annular wall 85 of the flange 80, so that the contact area between the planetary gear 61 and the flange 80 becomes small. Therefore, the frictional resistance generated when the planetary gear 61 rotates can be reduced.

Further, a disk-shaped contact portion 715 protruding upward is formed on the carrier main body 711 of the carrier 71. As shown in FIG. 4, the contact portion 715 of the carrier 71 is adapted to contact a part of the lower surface 625 (second contact surface) of each planetary gear 62, and the planetary gear 62 rotates. Then, a part of the lower surface 625 of the planetary gear 62 slides on the contact portion 715 of the carrier 71. A space S2 is formed between the planetary gear 62 and the carrier 71 on the outer side in the radial direction of the contact portion 715 of the carrier 71, and the gate portion 624 of the planetary gear 62 is housed in this space S2. Therefore, when the planetary gear 62 rotates, the gate portion 624 of the planetary gear 62 can move in the space S2 without interfering with the carrier 71. That is, the space S2 outside the contact portion 715 of the carrier 71 in the radial direction serves as a second gate portion moving space for moving the gate portion 624 of the planetary gear 62 between the planetary gear 62 and the carrier 71. There is.

As described above, in the present embodiment, the gate portion 624 of the planetary gear 62 is configured to move in the space S2 between the planetary gear 62 and the carrier 71, so that when the planetary gear 62 rotates, it moves. The gate portion 624 of the planetary gear 62 can move in the space S2 without interfering with the carrier 71. Further, when the planetary gear 62 rotates, only a part of the lower surface 625 of the planetary gear 62 slides into contact with the contact portion 715 of the carrier 71, so that the contact area between the planetary gear 62 and the carrier 71 becomes smaller. Therefore, the frictional resistance generated when the planetary gear 62 rotates can be reduced.

The planetary gear reduction device 22 in the above-described embodiment includes a two-stage planetary gear mechanism, but the number of planetary gear mechanisms included in the planetary gear reduction device 22 is not limited to this, and the number of planetary gear mechanisms is not limited to this. It may include a mechanism, or may include a planetary gear mechanism having three or more stages. Further, the number of planetary gears included in each planetary gear mechanism is not limited to the one shown in the figure.

The terms "upper", "upper", "lower", "lower", and other terms indicating the positional relationship used in the present specification are used in relation to the illustrated embodiment. It changes depending on the relative positional relationship of the devices.

Although the preferred embodiment of the present invention has been described so far, it goes without saying that the present invention is not limited to the above-described embodiment and may be implemented in various different forms within the scope of the technical idea.

1 Drive device 10 Frame 11 Upper flange part 12 Lower flange part 13 Fixed part 20 Geared motor 21 Motor 22 Planetary gear reduction device 23 Gear case 24 Motor shaft 25 Pinion (first sun gear)
30 Reed screw 31 Upper bearing 32 Lower bearing 40 Moving member 41 Nut part 42 Sliding part 50 Guide shaft 61 Planetary gear (first planetary gear)
62 Planetary gears (second planetary gears)
71 carrier (first carrier)
72 carriers (second carrier)
80 Flange 85 Circular wall 231 Bearing holding part 232 Internal gear 233 Cylindrical part 234 Rectangular plate-shaped part 612 Bearing recess (first bearing recess)
614 Gate (first gate)
615 Bottom surface (first contact surface)
622 Bearing recess (second bearing recess)
624 Gate (second gate)
625 Bottom surface (second contact surface)
711 Carrier body 712 Solid shaft (1st solid shaft)
713 pinion (second sun gear)
715 Contact part 721 Carrier body 722 Solid shaft part (second solid shaft part)
723 Axle connection part S1 First gate part movement space S2 Second gate part movement space

Claims (8)

A planetary gear speed reducer that slows down the rotation of the input shaft and transmits it to the output shaft.
The first sun gear connected to the input shaft and
A first planetary gear made of resin, the first planetary gear that meshes with the first sun gear and rotates with the rotation of the first sun gear.
A first carrier that is rotatable coaxially with the first sun gear and that holds the first planetary gear rotatably.
It includes an internal gear that revolves around the first sun gear and holds the first planetary gear.
The first carrier has a first solid shaft portion that extends coaxially with the first planetary gear.
On the output shaft side of the first planetary gear, a first bearing recess for receiving the first solid shaft portion of the first carrier is formed.
On the input shaft side of the first planetary gear, a first gate portion protruding toward the input shaft side is formed.
Planetary gear speed reducer. The planetary gear reduction device according to claim 1, wherein the first gate portion of the first planetary gear is located on the central axis of the first planetary gear. Further comprising a flange having an annular wall that contacts a portion of the first contact surface on the input shaft side of the first planetary gear.
Moving the first gate portion for moving the first gate portion of the first planetary gear between the first planetary gear and the flange inside the annular wall of the flange in the radial direction. Space is defined,
The planetary gear speed reducer according to claim 1. The first carrier has a second sun gear that is located coaxially with the first sun gear.
The planetary gear speed reducer
A second planetary gear made of resin, which is a second planetary gear that meshes with the second sun gear and rotates with the rotation of the second sun gear.
A second carrier that is rotatable coaxially with the second sun gear and further includes a second carrier that rotatably holds the second planetary gear.
The internal gear holds the second planetary gear so as to revolve around the second sun gear.
The second carrier has a second solid shaft portion that extends coaxially with the second planetary gear.
On the output shaft side of the second planetary gear, a second bearing recess for receiving the second solid shaft portion of the second carrier is formed.
On the input shaft side of the second planetary gear, a second gate portion protruding toward the input shaft side is formed.
The planetary gear speed reducer according to claim 1. The planetary gear reduction device according to claim 4, wherein the second gate portion of the second planetary gear is located on the central axis of the second planetary gear. The first carrier has a contact portion that contacts a part of the second contact surface on the input shaft side of the second planetary gear.
To move the second gate portion of the second planetary gear between the second planetary gear and the first carrier to the outside of the contact portion of the first carrier in the radial direction. The second gate movement space of is defined,
The planetary gear speed reducer according to claim 4. The planetary gear speed reducer according to claim 1,
A geared motor comprising a motor having a motor shaft connected to the first sun gear of the planetary gear speed reducer. A drive device that moves an object to be driven along the axial direction.
The geared motor according to claim 7 and
The frame to which the geared motor is attached and
A reed screw that extends in the axial direction and is rotated by the geared motor,
A drive device including a movable member having a nut portion screwed into the lead screw.

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