JP2023064941A - Drive unit - Google Patents

Abstract

To reduce noise while improving durability and power transmission efficiency of a drive unit.SOLUTION: A drive unit 1A in one embodiment includes: a motor 10; a first planetary gear mechanism to which rotating driving force output from the motor 10 is input; and a second planetary gear mechanism to which rotating driving force output from the planetary gear mechanism is input. The first planetary gear mechanism includes: a plurality of resin first planetary gears 22; and a resin case 25 having an inner peripheral surface on which a first internal gear 23 engaging with the first planetary gears 22 is formed. The second planetary gear mechanism includes: a plurality of metallic second planetary gears 32; and a metallic case 35 having an inner peripheral surface on which a second internal gear 33 engaging with the second planetary gears 32 is formed.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a driving device, and more particularly to a driving device that outputs rotational driving force.

2. Description of the Related Art A drive device is known that reduces the rotational speed of a rotational driving force output from a power source and increases the rotational force for output. For example, Patent Literature 1 describes a drive unit that includes a motor as a power source and a planetary gear train as a reduction mechanism.

JP 2013-221622 A

Driving devices such as those described above are required to reduce noise while improving durability and power transmission efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to reduce noise while improving the durability and power transmission efficiency of a driving device.

A driving device of one embodiment includes a motor, a first planetary gear mechanism to which rotational driving force output from the motor is input, and a second planetary gear mechanism to which rotational driving force output from the first planetary gear mechanism is input. and a planetary gear mechanism.

The first planetary gear mechanism includes a first sun gear mounted on the rotating shaft of the motor, a plurality of first planetary gears arranged around the first sun gear, and a plurality of the first planetary gears. A first planetary carrier that connects a plurality of the first planetary gears to each other and rotatably supports each of the first planetary gears; a first case having gear teeth forming an internal gear and containing at least the first sun gear and the plurality of first planetary gears.

The second planetary gear mechanism includes a second sun gear integrally formed with the first planetary carrier, a plurality of second planetary gears arranged around the second sun gear, and a plurality of the second planetary gears. a second internal gear arranged around a second planetary gear, a second planetary carrier that connects a plurality of the second planetary gears to each other and rotatably supports each of the second planetary gears; a second case formed with gear teeth forming two internal gears and housing at least the second sun gear and the plurality of second planetary gears.

The first case is made of resin, while the second case is made of metal. Also, the first sun gear, the first planetary gear, and the first internal gear are made of resin, while the first planetary carrier is made of metal. Furthermore, the second sun gear, the second planetary gear, the second internal gear and the second planetary carrier are made of metal.

According to the present invention, a low-noise driving device with improved durability and power transmission efficiency is realized.

It is an external appearance perspective view of a drive device. It is a sectional view of a drive. FIG. 4 is a perspective view of a first sun gear; FIG. 2 is a cross-sectional view taken along line AA in FIG. 1; FIG. 2 is a cross-sectional view taken along line BB in FIG. 1; FIG. 2 is a cross-sectional view taken along line CC in FIG. 1;

Hereinafter, details of the drive device according to one embodiment will be described with reference to the drawings. In principle, the same reference numerals are used for the same or substantially the same elements in all the drawings referred to in the following description. Also, elements that are the same or substantially the same as the elements that have been described once will not be described repeatedly in principle.

<Overall Configuration of Driving Device>
As shown in FIGS. 1 and 2, the driving device 1A has a motor 10, a first planetary gear mechanism 20, a second planetary gear mechanism 30, a third planetary gear mechanism 40 and an output shaft 50. FIG.

Motor 10 is a brushless motor. More specifically, motor 10 is a stepping motor driven by a DC pulse voltage input via a driver. From another point of view, the motor 10 is a pulse motor. The motor 10 includes a cylindrical motor housing 11, a rotating shaft 12, and the like.

A rotational driving force output from the motor 10 is input to the first planetary gear mechanism 20 . The first planetary gear mechanism 20 reduces the rotational speed of the input rotational driving force and outputs it. The rotational driving force output from the first planetary gear mechanism 20 is input to the second planetary gear mechanism 30 . The second planetary gear mechanism 30 further reduces the rotational speed of the input rotational driving force and outputs it. The rotational driving force output from the second planetary gear mechanism 30 is input to the third planetary gear mechanism 40 . The third planetary gear mechanism 40 further reduces the rotation speed of the input rotational driving force and outputs it to the output shaft 50 .

As described above, the driving device 1A includes a three-stage planetary gear mechanism that is connected so as to be able to transmit power. From another point of view, the first planetary gear mechanism 20 is a first stage reduction mechanism, the second planetary gear mechanism 30 is a middle stage reduction mechanism, and the third planetary gear mechanism 40 is a final stage reduction mechanism. That is, the driving device 1A has a power source and a multi-stage speed reduction mechanism.

<First Planetary Gear Mechanism (First Stage Reduction Mechanism)>
The first planetary gear mechanism 20 includes a first sun gear 21, a plurality of first planetary gears 22, a first internal gear 23, a first planetary carrier 24 and a first case 25 shown in FIG.

≪First sun gear≫
The first sun gear 21 is attached to the tip of the rotating shaft 12 of the motor 10 . From another point of view, the first sun gear 21 is a pinion gear attached to the tip of the rotating shaft 12 .

The first sun gear 21 has a double structure shown in FIG. Specifically, the first sun gear 21 has a double structure consisting of an inner member 21a and an outer member 21b provided around the inner member 21a.

The first sun gear 21 having the double structure is formed by filling the material of the outer member 21b into a mold in which the inner member 21a is arranged. That is, the first sun gear 21 is an insert-molded product (two-color molded product), and the inner member 21a and the outer member 21b are integrated.

At the center of the inner member 21a, there is provided a shaft hole 26 into which the end of the rotating shaft 12 of the motor 10 is fitted. On the other hand, a plurality of gear teeth forming the first sun gear 21 are provided on the outer peripheral surface of the outer member 21b. The inner member 21a and the outer member 21b are made of different materials. More specifically, the inner member 21a is made of a material different from the material of the outer member 21b and having a lower elastic modulus than the material of the outer member 21b. Specifically, the inner member 21a of this embodiment is made of rubber, and the outer member 21b is made of resin.

<<First Planetary Gear and First Planetary Carrier>>
A plurality of first planetary gears 22 are arranged around the first sun gear 21, as shown in FIG. 4A. More specifically, three first planetary gears 22 are arranged around the first sun gear 21 at regular intervals (120° intervals).

Each first planetary gear 22 is made of resin. Also, the three first planetary gears 22 are connected to each other by a first planetary carrier 24 and are rotatably supported.

The first planetary carrier 24 is made of metal. Furthermore, three support shafts 27 are integrally formed on one side of the first planetary carrier 24 , and each support shaft 27 is inserted through the center of the corresponding first planetary gear 22 . As a result, each first planetary gear 22 can rotate around the support shaft 27 as a rotation axis. Also, the three first planetary gears 22 are rotatable integrally with the first planetary carrier 24 .

≪First internal gear≫
The first internal gear 23 is arranged around the three first planetary gears 22 and surrounds the three first planetary gears 22 . From another point of view, the three first planetary gears 22 are arranged between the first sun gear 21 and the first internal gear 23 . Also, each first planetary gear 22 meshes with the first sun gear 21 and the first internal gear 23 .

As a result, when the first sun gear 21 is rotated by the rotational driving force output from the motor 10 , each of the first planetary gears 22 rotates (rotates) about the support shaft 27 as the rotation axis. rotate (revolve) around Further, as the first planetary gear 22 rotates (revolves), the first planetary carrier 24 rotates (rotates).

The first internal gear 23 is composed of a plurality of gear teeth 23 a formed on the inner peripheral surface of the first case 25 . From another point of view, the first internal gear 23 is integrally formed inside the first case 25 . In other words, the first internal gear 23 is part of the first case 25 .

The first case 25 is made of resin. A plurality of gear teeth 23 a forming the first internal gear 23 are formed at the same time as other portions of the first case 25 . That is, the first internal gear 23 is made of resin. In the following description, the first case 25 may be called "resin case 25".

As shown in FIGS. 1 and 2, the resin case 25 has a cylindrical shape with an outer diameter substantially the same as that of the motor housing 11, and both ends in the longitudinal direction are open. The resin case 25 houses at least the first sun gear 21 and the plurality of first planetary gears 22 . More specifically, all of the first sun gear 21 and the plurality of first planetary gears 22 and part of the first planetary carrier 24 are housed in the resin case 25 . From another point of view, part of the first planetary carrier 24 protrudes outside the resin case 25 .

<Second planetary gear mechanism (middle speed reduction mechanism)>
The second planetary gear mechanism 30 includes a second sun gear 31, a plurality of second planetary gears 32, a second internal gear 33, a second planetary carrier 34 and a second case 35 shown in FIG.

≪Second sun gear≫
The second sun gear 31 is integrally formed with the metal first planetary carrier 24 . That is, the second sun gear 31 is made of metal. More specifically, the second sun gear 31 is integrally formed on the other side of the first planetary carrier 24 opposite to the one side of the first planetary carrier 24 on which the support shaft 27 is integrally formed.

From another point of view, the support shaft 27 is formed by a part of the first planetary carrier 24 arranged inside the resin case 25, and the other part of the first planetary carrier 24 protruding outside the resin case 25. A second sun gear 31 is formed by A second sun gear 31 that is part of the first planetary carrier 24 protrudes from the first case 25 and enters the second case 35 . As a result, the first planetary carrier 24 straddles the first case 25 and the second case 35 .

<<Second Planetary Gear and Second Planetary Carrier>>
A plurality of second planetary gears 32 are arranged around the second sun gear 31, as shown in FIG. 4B. More specifically, three second planetary gears 32 are arranged at equal intervals (120° intervals) around the second sun gear 31 .

Each second planetary gear 32 is made of metal. Also, the three second planetary gears 32 are connected to each other by a second planetary carrier 34, and are rotatably supported.

The second planetary carrier 34 is made of metal. Furthermore, three support shafts 37 are integrally formed on one side of the second planetary carrier 34 , and each support shaft 37 is inserted through the center of the corresponding second planetary gear 32 . As a result, each second planetary gear 32 is rotatable around the support shaft 37 as a rotation axis. Also, the three second planetary gears 32 are rotatable integrally with the second planetary carrier 34 .

≪Second internal gear≫
The second internal gear 33 is arranged around the three second planetary gears 32 and surrounds the three second planetary gears 32 . From another point of view, the three second planetary gears 32 are arranged between the second sun gear 31 and the second internal gear 33 . Also, each of the second planetary gears 32 meshes with the second sun gear 31 and the second internal gear 33 .

As a result, when the second sun gear 31 (the first planetary carrier 24) rotates, each of the second planetary gears 32 rotates (rotates) about the support shaft 37 as the rotation axis, and rotates around the second sun gear 31. It rotates (revolves). Further, as the second planetary gear 32 rotates (revolves), the second planetary carrier 34 rotates (rotates).

The second internal gear 33 is composed of a plurality of gear teeth 33 a formed on the inner peripheral surface of the second case 35 . From another point of view, the second internal gear 33 is integrally formed inside the second case 35 . In other words, the second internal gear 33 is part of the second case 35 .

The second case 35 is made of metal. The plurality of gear teeth 33a forming the second internal gear 33 may be formed simultaneously with other portions of the second case 35, or may be formed separately. For example, the gear teeth 33a and other parts of the second case 35 can be formed simultaneously by metal injection molding. Alternatively, the gear teeth 33a may be formed by cutting the inner peripheral surface of the cylindrical case body. In any case, the second internal gear 33 is made of metal. In the following description, the second case 35 may be called "metal case 35".

As shown in FIGS. 1 and 2, the metal case 35 has a cylindrical shape with an outer diameter substantially the same as that of the motor housing 11 and the resin case 25, and is open at both ends in the longitudinal direction. The metal case 35 houses the second sun gear 31 , the plurality of second planetary gears 32 and the second planetary carrier 34 .

The end of the resin case 25 and the end of the metal case 35 are butted against each other. The end portions of the resin case 25 and the metal case 35 that are butted against each other are formed with recesses and protrusions that can be fitted to each other.

<Third Planetary Gear Mechanism (Final Stage Reduction Mechanism)>
The third planetary gear mechanism 40 includes a third sun gear 41, a plurality of third planetary gears 42, a third internal gear 43, a third planet carrier 44 and a second case (metal case) 35 shown in FIG. there is

≪Third sun gear≫
The third sun gear 41 is integrally formed with the second planetary carrier 34 made of metal. That is, the third sun gear 41 is made of metal. More specifically, the third sun gear 41 is integrally molded on the other side of the second planetary carrier 34 opposite to the one side of the second planetary carrier 34 integrally molded with the support shaft 37 . From another point of view, a part of the second planetary carrier 34 forms the support shaft 37 and another part of the second planetary carrier 34 forms the third sun gear 41 .

<<Third Planetary Gear and Third Planetary Carrier>>
A plurality of third planetary gears 42 are arranged around the third sun gear 41, as shown in FIG. 4C. More specifically, three third planetary gears 42 are arranged around the third sun gear 41 at regular intervals (120° intervals).

Each third planetary gear 42 is made of metal. In addition, the three third planetary gears 42 are connected to each other by a third planetary carrier 44 and are rotatably supported.

The third planetary carrier 44 is made of metal. Furthermore, three support shafts 47 are integrally formed on one side of the third planetary carrier 44 , and each support shaft 47 is inserted through the center of the corresponding third planetary gear 42 . As a result, each third planetary gear 42 is rotatable around the support shaft 47 as a rotation axis. Also, the three third planetary gears 42 are rotatable integrally with the third planetary carrier 44 .

≪Third internal gear≫
The third internal gear 43 is arranged around and surrounds the three third planetary gears 42 . From another point of view, the three third planetary gears 42 are arranged between the third sun gear 41 and the third internal gear 43 . Each third planetary gear 42 meshes with the third sun gear 41 and the third internal gear 43 .

As a result, when the third sun gear 41 (the second planetary carrier 34) rotates, each of the third planetary gears 42 revolves around the third sun gear 41 while rotating (rotating) about the support shaft 47 as the rotation axis. It rotates (revolves). Further, as the third planetary gear 42 rotates (revolves), the third planetary carrier 44 rotates (rotates).

The third internal gear 43 is composed of a plurality of gear teeth 43 a formed on the inner peripheral surface of the metal case 35 . From another point of view, the third internal gear 43 is integrally formed inside the metal case 35 . More specifically, the second internal gear 33 is constituted by a longitudinal part of the gear teeth formed on the inner peripheral surface of the metal case 35, and the gear teeth provided on the inner peripheral surface of the metal case 35 The third internal gear 43 is configured by the other part in the longitudinal direction of . That is, a part of the gear teeth formed on the inner peripheral surface of the metal case 35 in the longitudinal direction corresponds to the gear teeth 33a (FIG. 4B), and the longitudinal direction of the gear teeth formed on the inner peripheral surface of the metal case 35 The remainder of the directions correspond to gear teeth 43a (FIG. 4C).

As described above, the third internal gear 43 is integrally formed inside the metal case 35 together with the second internal gear 33 . In other words, the second internal gear 33 and the third internal gear 43 are part of the metal case 35 .

As shown in FIG. 2, one end of the output shaft 50 is fitted in the third planetary carrier 44 and is connected to the third planetary carrier 44 so as not to rotate relative to it. Therefore, the output shaft 50 rotates integrally with the third planetary carrier 44 .

<Frame>
As shown in FIG. 1, the driving device 1A has a frame 60 that surrounds the motor 10, the resin case 25 and the metal case 35 and integrates them. From another point of view, the motor 10 , the first planetary gear mechanism 20 , the second planetary gear mechanism 30 and the third planetary gear mechanism 40 are integrated by the frame 60 .

The frame 60 includes a main body 61 containing the motor 10, the resin case 25 and the metal case 35, and a lid member 62 joined to one longitudinal end of the main body 61. As shown in FIG. The cover member 62 is welded to one longitudinal end of the main body 61 to form another side wall 63b facing the side wall 63a of the frame 60. As shown in FIG.

The frame 60 has a rear wall 64, a bottom wall 65 and a top wall 66 in addition to the side walls 63a and 63b. Side walls 63 a , rear wall 64 , bottom wall 65 and top wall 66 are formed by parts of main body 61 . In the following description, the side wall 63a may be called "left side wall 63a" and the side wall 63b may be called "right side wall 63b".

That is, the frame 60 has a left side wall 63 a , a back side wall 64 , a bottom side wall 65 and a top side wall 66 formed by the main body 61 and a right side wall 63 b formed by the lid member 62 . One surface (front surface) of the frame 60 facing the rear wall 64 is open.

The motor 10, the resin case 25, and the metal case 35 have the same or substantially the same outer diameter, and are arranged in a line inside the frame 60 in this order. From another point of view, the motor 10, the first planetary gear mechanism 20, the second planetary gear mechanism 30 and the third planetary gear mechanism 40 are arranged in a line inside the frame 60 in this order.

One end side (left end side/rear end side) of the motor 10 is in contact with the inner surface of the left side wall 63 a of the frame 60 . One end side (left end side/rear end side) of the resin case 25 is the other end side of the motor 10 opposite to the one end side (left end side/rear end side) of the motor 10 in contact with the left side wall 63 a of the frame 60 . (right end side/tip side).

One end (left end/rear end) of the metal case 35 is connected to the other end (right end) of the resin case 25 opposite to the one end (left end/rear end) of the resin case 25 in contact with the motor 10 . side/tip side).

One end (left end/rear end) of the metal case 35 that is in contact with the resin case 25 and the other end (right end/front end) of the metal case 35 opposite to the inner surface of the right side wall 63b of the frame 60 is in contact with

From another point of view, the motor 10, the resin case 25 and the metal case 35 are sandwiched between the left side wall 63a and the right side wall 63b of the frame 60 facing each other and are inseparably integrated. However, the motor 10, resin case 25 and metal case 35 are not fixed to each other. Motor 10 , resin case 25 and metal case 35 are also not fixed to frame 60 . Therefore, by removing the lid member 62 from the main body 61, the motor 10, the resin case 25, and the metal case 35 can be taken out from the frame 60 or separated from each other. As a result, the driving device 1A is easy to assemble, and it is easy to change the number of speed reduction steps and the speed reduction ratio.

In the driving device 1A having the above structure, the rotational driving force output from the motor 10 is transmitted in the order of the first planetary gear mechanism 20, second planetary gear mechanism 30, third planetary gear mechanism 40, and output shaft 50. be. In other words, the rotational driving force output from the motor 10 is transmitted and decelerated in the order of the first speed reduction mechanism, the middle speed reduction mechanism, and the final speed reduction mechanism.

Therefore, the load applied to the first planetary gear mechanism 20 is smaller than the load applied to the second planetary gear mechanism 30 and the third planetary gear mechanism 40 . On the other hand, the gears forming the first planetary gear mechanism 20 rotate at a higher speed than the gears forming the second planetary gear mechanism 30 and the third planetary gear mechanism 40 .

Also, the load applied to the third planetary gear mechanism 40 is larger than the load applied to the first planetary gear mechanism 20 and the second planetary gear mechanism 30 . On the other hand, the gears forming the third planetary gear mechanism 40 rotate at a lower speed than the gears forming the first planetary gear mechanism 20 and the second planetary gear mechanism 30 .

Therefore, in the present embodiment, the first planetary gear mechanism 20 is made of resin in order to prioritize the improvement of power transmission efficiency and the reduction of noise over the improvement of durability. More specifically, the first sun gear 21, the first planetary gear 22, and the first internal gear 23 (first case 25) are made of resin.

Examples of resin materials used as materials for the first sun gear 21 and the like include single resin materials such as polyacetal resin, polyimide resin, polyester resin, polycarbonate resin, acrylic resin, fluorine resin, carbon fiber, Composite resin materials mixed with glass fiber or the like can be mentioned.

On the other hand, the second planetary gear mechanism 30 and the third planetary gear mechanism 40 are made of metal, giving priority to improving durability over improving power transmission efficiency and reducing noise. More specifically, the second sun gear 31, the second planetary gear 32, the second internal gear 33 (second case 35), and the second planetary carrier 34 are made of metal. Also, the third sun gear 41, the third planetary gear 42, the third internal gear 43 (the second case 35) and the third planetary carrier 44 are made of metal.

Metal materials used for the second sun gear 31 and the like include carbon alloys, stainless steel, molybdenum steel, and the like. Examples of methods for manufacturing the second sun gear 31 and the like from metal materials include a metal injection molding method and a powder compaction method.

In other words, in the driving device 1A according to the present embodiment, a resin gear that is superior to metal gears in terms of power transmission efficiency and noise, and a metal gear that is superior in durability to resin gears are used in the right place. used in As a result, the driving device 1A achieves both improved durability and power transmission efficiency and reduced noise.

Furthermore, a first case 25 in which a first internal gear 23 (gear teeth 23a) is formed, and a second internal gear 33 (gear teeth 33a) and a third internal gear 43 (gear teeth 43a) in which are formed. 2 and the case 35 are separate bodies. From another point of view, the gear case is divided into two or more. As a result, the number of gear teeth 23a formed on the inner peripheral surface of the first case 25 and the number of gear teeth 33a, 43a formed on the inner peripheral surface of the second case 35 can be made different. That is, the number of teeth of the first internal gear 23 and the number of teeth of the second internal gear 33 and the third internal gear 43 can be made different. That is, the driving device 1A according to the present embodiment has a high degree of freedom in setting and changing the gear ratio (reduction ratio).

In addition, in this embodiment, the number of teeth of the first internal gear 23 is smaller than the number of teeth of the second internal gear 33 and the third internal gear 43 . Specifically, the number of teeth of the second internal gear 33 and the third internal gear 43 is "43", while the number of teeth of the first internal gear 23 is "40". As a result, wear of the first planetary gear mechanism 20, which rotates more than the second planetary gear mechanism 30 and the third planetary gear mechanism 40, is suppressed, and noise emitted from the first planetary gear mechanism 20 is reduced.

Furthermore, the first sun gear 21 of the driving device 1A according to this embodiment has a double structure. Specifically, the inner member 21a provided with the shaft hole 26 into which the rotating shaft 12 of the motor 10 is fitted is more elastic than the outer member 21b provided with the gear teeth forming the first sun gear 21. It is made of a material with a small modulus. In short, in this embodiment, the inner member 21a in contact with the rotating shaft 12 of the motor 10 is more flexible than the outer member 21b in contact with the first planetary gear 22. FIG.

Therefore, when the motor is started, all of the load connected to the drive device 1A (output shaft 50) is not directly applied to the motor 10. FIG. From another point of view, the load to which the driving device 1A is connected is temporarily absorbed by the elastic deformation of the inner member 21a. As a result, the motor 10 can be started even when the load to which the driving device 1A is connected is larger than the starting torque of the motor 10 .

The present invention is not limited to the above embodiments, and can be modified in various ways without departing from the scope of the invention. For example, fourth and fifth planetary gear mechanisms may be added after the third planetary gear mechanism. Further, the number and size of gears provided in each planetary gear mechanism and the number of gear teeth constituting each gear can be changed as appropriate.

A driving device to which the present invention is applied is suitable for use in compact cameras and portable information terminals. However, the use of the driving device to which the present invention is applied is not limited, and it can be used in various devices and equipment.

1A... Drive device, 10... Motor, 11... Motor housing, 12... Rotating shaft, 20... First planetary gear mechanism, 21... First sun gear, 21a... Inner member, 21b... Outer member, 22... First planetary gear , 23... First internal gear 23a... Gear tooth 24... First planetary carrier 25... First case (resin case) 26... Shaft hole 27... Support shaft 30... Second planetary gear mechanism 31... Second sun gear 32 Second planetary gear 33 Second internal gear 33a Gear tooth 34 Second planetary carrier 35 Second case (metal case) 37 Support shaft 40 Third Planetary gear mechanism 41 Third sun gear 42 Third planetary gear 43 Third internal gear 43a Gear tooth 44 Third planetary carrier 47 Support shaft 50 Output shaft 60 Frame , 61...Main body 62...Lid member 63a...Side wall (left side wall) 63b...Side wall (right side wall) 64...Back wall 65...Bottom wall 66...Top wall

Claims (8)

A drive having a motor, a first planetary gear mechanism to which rotational driving force output from the motor is input, and a second planetary gear mechanism to which rotational driving force output from the first planetary gear mechanism is input a device,
The first planetary gear mechanism is
a first sun gear mounted on the rotating shaft of the motor;
a plurality of first planetary gears arranged around the first sun gear;
a first internal gear arranged around the plurality of first planetary gears;
a first planetary carrier that couples the plurality of first planetary gears to each other and rotatably supports each of the first planetary gears;
a first case having gear teeth forming the first internal gear formed on an inner peripheral surface and housing at least the first sun gear and the plurality of first planetary gears;
The second planetary gear mechanism is
a second sun gear integrally formed with the first planetary carrier;
a plurality of second planetary gears arranged around the second sun gear;
a second internal gear arranged around the plurality of second planetary gears;
a second planetary carrier that couples the plurality of second planetary gears to each other and rotatably supports each of the second planetary gears;
a second case having gear teeth forming the second internal gear formed on an inner peripheral surface, and housing at least the second sun gear and the plurality of second planetary gears;
The first case is made of resin, while the second case is made of metal,
The first sun gear, the first planetary gear, and the first internal gear are made of resin, while the first planetary carrier is made of metal,
The driving device, wherein the second sun gear, the second planetary gear, the second internal gear and the second planetary carrier are made of metal. further comprising a third planetary gear mechanism that is housed in the second case and receives the rotational driving force output from the second planetary gear mechanism;
The third planetary gear mechanism is
a third sun gear integrally formed with the second planetary carrier;
a plurality of third planetary gears arranged around the third sun gear;
a third internal gear arranged around the plurality of third planetary gears;
a third planetary carrier that couples the plurality of third planetary gears to each other and rotatably supports each of the third planetary gears;
A part of the gear teeth provided on the inner peripheral surface of the second case constitutes the second internal gear, and another part of the gear teeth provided on the inner peripheral surface of the second case. The third internal gear is configured by
2. The driving device according to claim 1, wherein said third sun gear, said third planetary gear, said third internal gear and said third planetary carrier are made of metal. a frame surrounding the motor, the first case and the second case;
the motor, the first case and the second case are arranged in a line in this order inside the frame;
one end of the motor abuts against a side wall of the frame;
one end side of the first case contacts the other end side of the motor opposite to the one end side of the motor contacting the side wall of the frame;
one end side of the second case contacts the other end side of the first case opposite to the one end side of the first case contacting the motor;
2. The other end side of said second case opposite to the one end side of said second case that is in contact with said first case is in contact with another side wall of said frame that faces said side wall. Or the driving device according to 2. 3. The frame has a main body including the side wall against which the motor abuts, and a lid member joined to the main body forming the side wall of the frame against which the second case abuts. 4. The driving device according to 3. Claims 1 to 4, wherein the number of gear teeth formed on the inner peripheral surface of the first case and the number of gear teeth formed on the inner peripheral surface of the second case are different. A drive device according to any one of the preceding claims. 6. The device according to claim 5, wherein the number of gear teeth formed on the inner peripheral surface of the first case is smaller than the number of gear teeth formed on the inner peripheral surface of the second case. drive. the first sun gear has a dual structure consisting of integrated inner and outer members,
The inner member is provided with a shaft hole into which the rotating shaft of the motor is fitted,
Gear teeth forming the first sun gear are provided on the outer peripheral surface of the outer member,
The driving device according to any one of claims 1 to 6, wherein the inner member is made of a material different from the material of the outer member and having a lower elastic modulus than the material of the outer member. A driving device according to any one of claims 1 to 7, wherein the motor is a stepping motor.

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