JP2003130146A - Small-sized reducer and geared motor having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small reducer, which can avoid an overload state by stably maintaining slipping torque during slip rotation, and to provide a geared motor having the same. SOLUTION: In the small reducer 3 having a planetary gear mechanism 5, which is composed of a sun gear 10, a planetary gear 11, a carrier 12, a fixed internal gear 13, and a rotating internal gear 14, in a case 4 and also a torque limiter for allowing the fixed internal gear 13, to slip when the planetary gear mechanism 5 has been put in a heavy load state, an annular groove 122, having a concave section, is formed on an outer peripheral surface of the fixed internal gear 13 or an inner peripheral surface of the case 4, and the torque limiter is composed of an O-ring 121 fitted to the annular groove 122.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small reducer mounted mainly in a small electronic device such as a camera or a mobile phone and a geared motor including the same.

[0002]

2. Description of the Related Art Heretofore, as a compact reducer and a geared motor of this type, those described in, for example, JP-A-3-223547 have been known. This small reduction gear is composed of a planetary gear mechanism, which is the main component, and a two-divided structure housing the planetary gear mechanism, and is integrally attached to the motor via a motor-side case (geared motor). The planetary gear mechanism meshes with the sun gear fixed to the main shaft of the motor, two planetary gears that mesh with the sun gear, a carrier that supports the two planetary gears so that they can rotate and revolve around the sun gear, and the planetary gears. A fixed internal gear,
It is composed of a movable internal gear that meshes with a planetary gear and integrally forms an output shaft. Further, each of these components is formed by resin integral molding. An annular step portion is formed on the outer peripheral surface of the motor-side lower portion of the fixed internal gear, and an O-ring is attached to the annular step portion so as to contact the inner peripheral surface of the case (see FIG. 6 of the publication).
(A)). This prevents the fixed internal gear from slipping and causing the motor to become overloaded when a large external force acts on the output side.

[0003]

In such a conventional small speed reducer, the O-ring is mounted on the annular step of the fixed internal gear, so that it is crushed in the radial direction and deformed into an elliptical shape. When doing so, there was a problem that the fixed internal gear was pushed upward. However, if the annular step portion is formed to be sufficiently long vertically and the lower case is not pressed even if the O-ring is deformed, such a problem does not occur. However, in this case, the mounting position of the O-ring is not constant, and the actual sliding part becomes the inner peripheral part or the outer peripheral part of the O-ring at the time of slip rotation, and the starting torque becomes constant. The problem of disappearing occurs. Further, by forming the annular stepped portion, there is no portion for guiding the slip rotation at the lower end portion of the fixed internal gear, so that the fixed internal gear is apt to run out of shaft and the starting torque becomes unstable. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a small speed reducer capable of avoiding an overload condition and a geared motor equipped with the small speed reducer while stably maintaining the sliding torque during slip rotation.

[0005]

A compact speed reducer according to the present invention comprises:
The sun gear on the input side and the planetary gear that meshes with the sun gear,
A planetary gear mechanism consisting of a carrier that supports the planetary gear rotatably and revolvably around the sun gear, a fixed internal gear that meshes with the planetary gear, and a movable internal gear on the output side that meshes with the planetary gear In addition, in the small reduction gear with a torque limiter between the fixed internal gear and the case, which allows slip rotation of the fixed internal gear when the planetary gear mechanism reaches a high load state, An annular groove having a concave cross section is formed on the outer peripheral surface of the toothed gear or the inner peripheral surface of the case, and the torque limiter is mounted on the annular groove.
It is characterized by being composed of a ring.

According to this structure, the O-ring constitutes the torque limiter which allows slip rotation of the fixed internal gear under high load conditions, so that the planetary gear mechanism (and motor) is overloaded in a simple structure. Can be avoided. Further, since the O-ring forming the torque limiter is mounted in the annular groove of the concave cross section formed on the outer peripheral surface of the fixed internal gear or the inner peripheral surface of the case, the position of the O-ring in the annular groove is fixed. Along with this, the sliding contact portion of the O-ring with the fixed internal gear or the case during slip rotation is also constant. Furthermore, since the annular groove is formed in a concave cross section, the fixed internal gear is slip-rotated by being guided at at least both ends regardless of the axial position of the annular groove. Therefore, it is possible to prevent shaft deviation of the fixed internal gear during slip rotation.

Another miniature speed reducer of the present invention includes a sun gear on the input side, a planet gear that meshes with the sun gear, a carrier that supports the planet gear so that it can rotate and revolve around the sun gear, and a planet gear. A planetary gear mechanism consisting of a fixed internal gear that meshes and a movable internal gear on the output side that meshes with the planet gear is provided in the case, and the planetary gear mechanism is in a high load state between the fixed internal gear and the case. In a small reducer with a torque limiter that allows slip rotation of the fixed internal gear when reaching the limit, the torque limiter has a spring property formed on the outer peripheral surface of the fixed internal gear or the inner peripheral surface of the case. It is characterized in that it is composed of a protrusion.

According to this structure, the torque limiter that allows the slip rotation of the fixed internal gear is formed by the protrusion having the spring property formed on the outer peripheral surface of the fixed internal gear or the inner peripheral surface of the case. Therefore, it is possible to avoid the overload state with a simple structure without increasing the number of parts. Therefore, it is possible to effectively prevent the damage of the component parts due to the external force and the damage of the motor connected thereto. The protrusions are preferably continuous in an annular shape, but are not necessarily continuous and may be discontinuous.

Another miniature speed reducer of the present invention includes a sun gear on the input side, a planetary gear that meshes with the sun gear, a carrier that supports the planetary gear rotatably and revolvable around the sun gear, and a planetary gear. The case is equipped with a planetary gear mechanism consisting of a fixed internal gear that meshes with the output side movable internal gear that meshes with the planetary gear, and the planetary gear mechanism is in a high load state between the fixed internal gear and the case. In a small reducer equipped with a torque limiter that allows slip rotation of the fixed internal gear when it reaches the torque limiter, the torque limiter is a spring whose end is fixed to the case and is wound around the outer peripheral surface of the fixed internal gear. It is characterized by being composed of.

According to this structure, since the torque limiter for allowing the slip rotation of the fixed internal gear is constituted by the spring wound around the outer peripheral surface of the fixed internal gear (winding spring), the structure is simple. The overload condition can be avoided with. Therefore, it is possible to effectively prevent the damage of the component parts due to the external force and the damage of the motor connected thereto.

Another miniature speed reducer of the present invention comprises a sun gear on the input side, a planet gear that meshes with the sun gear, a carrier that supports the planet gear so that it can rotate and revolve around the sun gear, and a planet gear. In a small reduction gear equipped with a planetary gear mechanism, which comprises a fixed internal gear that meshes with the output internal movable gear that meshes with the planetary gear, a sun gear, a planetary gear,
Of the fixed internal gear and the movable internal gear, any two gears that mesh with each other are replaced with each other, and are brought into rolling contact with each other 2
It is characterized by being composed of two friction wheels.

According to this structure, when the external force acts on the output side, the friction wheels slip and rotate, so that the overloaded state can be avoided. Therefore, it is possible to effectively prevent the damage of the component parts due to the external force and the damage of the motor connected thereto.

In this case, it is preferable that the arbitrary two gears are a movable internal gear and a planetary gear that mesh with each other.

According to this structure, the gears closest to the output side are composed of friction wheels, and the external force from the output side can be efficiently released. Further, the gears that rotate at the lowest speed (high torque) can be configured by friction wheels.

A geared motor according to the present invention is characterized by comprising the above-mentioned small speed reducer of the present invention and a motor in which the small speed reducer is directly connected to a main shaft.

According to this structure, it is possible to effectively prevent damage to the components of the small reduction gear due to external force as well as damage due to heating of the motor.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A compact speed reducer and a geared motor including the same according to an embodiment of the present invention will be described below with reference to the accompanying drawings. 1 is an external perspective view of a geared motor, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a sectional view thereof. As shown in these figures, the geared motor 1 is composed of an ultra-small motor 2 and a small reducer 3 directly connected to the motor 2, and the motor 2 is, for example, a DC motor having a nominal diameter of about 6 mm. It is configured.

The small speed reducer 3 is provided in a substantially cylindrical case 4,
It is configured by incorporating the planetary gear mechanism 5 that forms the main body. The case 4 is an input side case 7 fixed to the motor 2.
And the output side case 8 that is joined to the input side case 7 in a snap-in manner are configured in two parts. On the other hand, the planetary gear mechanism 5 includes the input sun gear 1 directly connected to the motor 2.
0 and three planetary gears 11, 1 that mesh with the sun gear 10.
1, 11, a carrier 12 that supports the planetary gears 11 so as to be rotatable and revolvable around the sun gear 10, a fixed internal gear 13 that meshes with the planetary gears 11, and an output shaft 15 that meshes with the planetary gears 11. The movable internal gear 14 is formed integrally with the movable internal gear 14.

As shown in FIGS. 3 and 4, the input side case 7 has a cross groove 21 having a substantially cross shape in plan view inside.
It is integrally formed in a block shape, and a fitting opening 22 that fits into a boss 2b formed around the main shaft 2a of the motor 2 is formed in the central portion thereof. In the cross groove 21,
A pair of counterbore grooves 24, 24 for machine screws 23, 23 and a pair of fitting grooves 25, 2 for fixing the fixed internal gear 13.
5 and 5 are formed alternately in the circumferential direction. That is, the pair of counterbore grooves 24, 24 and the pair of fitting grooves 25, 25 are alternately arranged with their phases shifted by 90 ° in the circumferential direction. The input side case 7 includes a pair of counterbore grooves 24, 24.
Two small screws 2 screwed to the end surface 2c of the motor 2 via the
It is fixed to the output side end surface 2c of the motor 2 by screws 3 and 23.

By thus arranging the pair of counterbore grooves 24, 24 and the pair of fitting grooves 25, 25 in a cross shape, a dead space does not occur inside the input side case 7 and the input side case 7 is not formed. The space efficiency in the side case 7 can be improved. In addition, by this, the input side case 7
Can be made compact in height (length).

On the other hand, on the outer peripheral surface of the input side case 7, four locking projections 26 for snap-in and a pair of counterbore grooves 24, 24 and a pair of fitting grooves 25, 25 are provided. Two rectangular convex portions 27 are formed alternately in the circumferential direction. Each of the locking projections 26 is formed in a square spire shape with a guide slope 26a, and a locking hole 34 of an output side case 8 described later is locked by a snap-in method. Further, the output side case 8 is provided on the four rectangular convex portions 27.
The four notches 32 are fitted in, and the output side case 8 is positioned in the axial direction and the circumferential direction.

As shown in FIGS. 3 and 5, the output side case 8 is integrally molded in a substantially cylindrical shape by the peripheral wall portion 8a and the cover wall portion 8b on the front end side, and the central portion of the cover wall portion 8b. A circular slidable contact opening 31 that rotatably supports the movable internal gear 14 is formed in the shaft (details will be described later). At the joint portion of the output side case 8 in the peripheral wall portion 8a, four projecting pieces 33 are provided by the four notch portions 32 arranged evenly in the circumferential direction.
And a locking hole 34 for locking the locking projection 26 of the input side case 7 is formed in each of the projecting pieces 22.

Input side case 7 screwed to the motor 2
On the other hand, when the output side case 8 is pushed in from the axial direction after aligning the four cutout portions 32 with the four rectangular convex portions 27, the respective projecting pieces 33 of the output side case 8 are locked by the input side case. (Guide slope 26a) 26 overcoming the locking hole 3
It is locked in 4 by snap-in type. Further, in this state, the four cutout portions 32 of the output side case 8 are fitted into the four rectangular convex portions 27 of the input side case 7, and the output side case 8
Is fixedly connected to the input side case 7 in a state in which it does not come off.

As shown in FIGS. 2 and 3, the sun gear 1
Reference numeral 0 includes a sun gear forming portion 37 and a shaft hole forming portion 38 connected to the sun gear forming portion 37 on the side of the motor 2 and is integrally formed of resin or the like. The shaft hole forming portion 38 is formed to have a diameter slightly larger than that of the sun gear forming portion so as to support the sun gear forming portion, and a main shaft (input shaft) of the motor 2 is inserted through a shaft hole 39 having a substantially semicircular cross section.
It is mounted so as to be driven into 2a. Further, the sun gear forming portion 37 meshes with a large gear forming portion 44 of each planetary gear 11, which will be described later.

As shown in FIG. 3, FIG. 6 and FIG. 7, each planetary gear 11 is coaxial with the gear body 41, and a pair of support shaft portions 42 are provided so as to project coaxially from both ends of the gear body 41 in the axial direction.
a and 42b, which are integrally molded of resin or the like. The gear body 41 is integrally formed with a small gear forming portion 43 that meshes with the movable internal gear 14, and a large gear forming portion 44 that is continuous with the motor 2 side of the small gear forming portion 43. The sun gear 10 meshes with the fixed internal gear 13 and also meshes with it.

The small gear forming portion 43 and the large gear forming portion 44 have the same number of teeth and the same phase of each tooth, but different modules. Therefore, the pinion forming portion 43
Has a pitch circle diameter smaller than that of the large gear forming portion 44,
In addition, the contour line is contained within the contour line of the large gear forming portion 44. This makes it possible to obtain a desired reduction gear ratio and simplify the die cutting of the die.

The three planetary gears 11, 11, 11 thus configured are arranged at 120 ° point symmetric positions with respect to each other and their axes are parallel to each other, and each pair of supporting shaft portions 42a. , 42b are rotatably supported by the carrier 12 with both ends. As a result, each planetary gear 1
1 revolves around the sun gear 10 via the carrier 12 while rotating on its axis. In the present embodiment, the planetary gear 11
The upper part of the figure is the small gear forming part 43 having a small pitch circle diameter, and the lower part is the large gear forming part 44 having a large pitch circle diameter. The form (difference in pitch circle diameter, difference in number of teeth, and mutual phase) is appropriately determined depending on the reduction ratio and the like, and the present invention is not limited to the above embodiment in this respect.

The carrier 12 is 2 at a substantially intermediate position in the axial direction.
The divided input side piece 12a and output side piece 12b are joined to each other. More specifically,
The carrier 12 is the large gear forming portion 4 of the planetary gear 11.
4 at the position corresponding to the boundary between the pinion 4 and the pinion forming portion 43
The input side piece 12a is divided and the output side piece 12b faces the small gear forming portion 43.

The input-side piece 12a comprises a thick disk-shaped bearing portion 51 and three columnar connecting portions 52, 52, 52 extending from the bearing portion 51 toward the output-side piece 12b. Is molded into. A circular escape opening 53 into which the sun gear 10 is loosely inserted is formed in the center of the bearing portion 51. The three columnar connecting portions 52 are evenly arranged by alternately sandwiching the three planetary gears 11 in the circumferential direction (120 ° point symmetry), and the bearing portion 51 is located between the columnar connecting portions 52, 52. The planetary gear (spindle 42
a) Three bearing holes 54, 5 for rotatably supporting 11
4, 54 are formed.

At the tip of each columnar connecting portion 52, a columnar joining pin 55 for joining to the output side piece 12b is projected. Further, each columnar connecting portion 52 is formed in a substantially triangular cross-section, and two sides facing the planetary gear 11 are formed in an arc shape so as to escape the planetary gear 11, and the other one side located on the outer side. Are formed in an arc shape so as to be flush with the outer peripheral surface of the bearing portion 51. The end of the bearing portion 51 on the motor 2 side is an annular protrusion 56 that is thinly formed, and the carrier 12 has the annular protrusion 56.
Is rotatably supported by the annular stepped portion 76 of the fixed internal gear 13 and is axially positioned (details will be described later).

Similarly, the output side piece 12b includes a thick-walled disc-shaped bearing portion 61 and the input side piece 1 from the bearing portion 61.
Three columnar connecting portions 62, 62, 6 extending toward 2a
2 and are integrally formed of resin or the like. A circular shaft hole 63 that rotatably engages with a shaft projection 84 of the movable internal gear 14 described later is formed in the center of the bearing portion 61 (details will be described later). Further, around the circular shaft hole 63, an annular convex portion 64 that slightly projects in the axial direction toward the movable internal gear 14 is formed. As a result, the carrier 12 is positioned in the axial direction, and when the movable internal gear 14 is in rotational contact with the output side piece 12b, this is done in a small area.

Three columnar connecting portions 6 of the output side piece 12b
2 are evenly arranged by alternately sandwiching the three planetary gears 11 in the circumferential direction (120 ° point symmetry), and the bearing portion 61 is located between the columnar coupling portions 62, 62, and the planetary gears ( Three bearing holes 65, 65, 65 for rotatably supporting the support shaft portion 42b) 11 are formed. A joint hole 66 into which the joint pin 55 of the input-side piece 12a is joined is formed at the axis of each columnar connecting portion 62.
It penetrates through the columnar connecting portion 62 and the bearing portion 61. As a result, the bearing portion 61 of the output side piece 12b has three
One bearing hole 65 and three joint holes 66 are formed alternately and at equal pitches in the circumferential direction.

Similarly to the above, each columnar connecting portion 62 is formed in a substantially triangular cross section, two sides facing the planetary gear 11 are formed in an arc shape, and the other one side located outside is a circle. The projection is formed in an arc shape. The pinion connecting portion 62 of the output side piece 12b has a pinion gear forming portion 43 of the planetary gear 11.
The columnar connecting portion 52 of the input-side piece 12 a faces the large gear forming portion 44 of the planetary gear 11. Therefore, the cross section of the columnar connecting portion 62 of the output side piece 12b is formed to be slightly larger than the cross section of the columnar connecting portion 52 of the input side piece 12a. As a result, the input side piece 12b
A connecting pin 55 is attached to the columnar connecting portion 52 of the output side piece 1.
The joint holes 66 can be formed (molded) in the columnar connecting portions 62 of 2b without difficulty.

After assembling the three planetary gears 11, the input side piece 12a and the output side piece 12b are joined together to form bearings 51, 6 having the same diameter.
The ones face each other in parallel with each other, and the planetary gears 11 are rotatably supported by the ones. Further, in this state, the carrier 12 is rotatably supported coaxially on the output side by the shaft projection 84 of the movable internal gear 14, and coaxially on the input side in the annular step of the fixed internal gear 13. It is rotatably supported by the portion 76.

As a result, the rotating carrier 12 can be supported by both ends, and can also be supported by the fixed internal gear 13 and the movable internal gear 14 which require higher component accuracy than the case 4 or the like. You can Therefore, the carrier 12 and the planetary gear 11 including the rotating portion can be assembled with high accuracy, and the loss (friction loss) in power transmission can be reduced. In addition, the carrier 12
When the movable internal gear 13 and the movable internal gear 13 rotate in the same direction, the relative rotation difference can be reduced, and the friction loss between the two can be further reduced.

As shown in FIGS. 3 and 8, the fixed internal gear 13 is connected to the fixed gear forming portion 71 that meshes with the large gear forming portion 44 of each planetary gear 11, and to the motor 2 side of the fixed gear forming portion 71. It is composed of a gear support portion 72 and is integrally formed of resin or the like. The axial length (tooth width) of the fixed gear formation portion 71 is formed sufficiently larger than the length of the large gear formation portion 44 of the planetary gear 11 that meshes with the fixed gear formation portion 71. Further, on the movable internal gear 14 side of the fixed gear forming portion 71, a thin fixed-side annular sliding contact portion 73 with which the movable internal gear 14 is rotatably engaged is formed via a step portion. In this case, the movable side annular sliding contact portion 86 of the movable internal gear 14 which will be described later is disposed inside and the fixed side annular sliding contact portion 73 is disposed outside.

By the way, as shown in FIG. 8, the fixed-side annular sliding contact portion 73 is formed with three notched portions 74, 74, 74 which are evenly arranged in the circumferential direction. As described above, the fixed internal gear 13 is an integrally molded product such as a resin and is extremely small. Therefore, in the die cutting at the time of molding, three cutout portions 74 are formed as the abutting portions of the projecting pins P (see the phantom line in the drawing). That is, when the fixed internal gear 13 is pulled out from the mold, the three protruding pins P are attached to the three cutout portions 74.
I'm trying to pull it out evenly against the.

As a result, the protruding pin P can be formed to have a relatively large diameter, and the fixed internal gear 13
It is possible to abut against the thick portion (end face of the fixed gear forming portion 71) of. Therefore, it is possible to smoothly perform die cutting, and at that time, it is possible to effectively prevent the fixed internal gear 13 from being damaged. The size and the number (plurality) of the cutout portions 74 are arbitrary as long as they do not hinder the smooth rotation of the movable internal gear 14.

The gear support portion 72 has a shape like an end face wall connected to the fixed gear formation portion 71, and the center portion thereof has
A circular opening 75 that escapes the shaft hole forming portion 38 of the sun gear 10 is formed. Further, an annular step portion 76 is formed on the inner peripheral surface of the gear support portion 72, and the carrier (the annular protrusion 56 thereof) 12 is rotatable in the annular step portion 76 while being axially positioned. Supported by.

On the other hand, on the motor 2 side of the gear support 72,
The pair of fitting protrusions 77, 77 are formed so as to be point-symmetric with respect to each other by 180 °. As described above, the pair of fitting grooves 25, 25 is formed in the input side case 7, and the pair of fitting projections 77, 77 are fitted into the pair of fitting grooves 25, 25 to fix the inside of the fixed portion. By mounting the toothed gear 13 on the input side case 7, the fixed internal gear 13 is fixed to the input side case 7 in a rotation-stopped state.

As shown in FIGS. 3, 5 and 7, the movable internal gear 14 comprises a bottomed cylindrical gear body 81 and an output shaft 15 projecting axially forward from the gear body 81. It is integrally molded with resin. The gear body 81 is
It is composed of a cylindrical movable gear forming portion 82, an end face wall portion 83 connected to the movable gear forming portion 82, and a shaft protrusion 84 formed inside the end face wall portion 83, and the carrier 12 is rotated by the shaft protrusion 84. It is supported freely. Also, the output shaft 15
Has a pair of annular shift preventing portions 85, 85, and is extended outside the end surface wall portion 83 coaxially with the shaft protrusion 84.

Similar to the fixed gear forming portion 71, the movable gear forming portion 82 has an axial length (tooth width) sufficiently larger than that of the small gear forming portion 43 of the planetary gear 11 meshing therewith. Has been formed. Further, on the fixed internal gear 13 side of the movable gear forming portion 82, a thin-walled movable side annular sliding contact portion 86 with which the fixed side annular sliding contact portion 73 is rotatably engaged is formed via a step portion. Has been done.

On the other hand, the shoulder portion of the end face wall portion 83 on the output shaft 15 side is an annular step portion connected to the one shift preventing portion 85, and this end face wall step portion 87 is the output side case 8 described above. Is rotatably engaged with the sliding contact opening 31. That is, in the movable internal gear 14, the movable annular slide contact portion 86 is rotatably brought into sliding contact with the fixed annular slide contact portion 73 of the fixed internal gear 13, and the end surface wall step 87 is provided in the output side case 8. The slide contact opening 31 is rotatably slidably contacted and is rotatably supported at two axial positions. This makes it possible to improve the rotation support accuracy of the movable internal gear 14, and to rotate the movable internal gear 14 coaxially with the sun gear 10 with high accuracy. In addition, the output side case 8 of the movable internal gear 14
The output side case 8 itself can be made compact in terms of length (length) by using the end face wall step portion 87 instead of the output shaft 15 as the rotation support portion for.

On the other hand, the shaft protrusion 84 is slightly tapered toward the carrier 12, and the circular shaft hole 63 of the carrier 12 is rotatably engaged with the shaft protrusion 84. As described above, the movable internal gear 14 is an integrally molded product made of resin or the like, and the shaft projection 84 protrudes and serves as the abutting portion of the pin P when the die is removed during molding (see the phantom line in FIG. 7). For this reason,
By making the shaft projection 63 into a tapered shape, the movable internal gear 14 can be smoothly demolded, and the movable internal gear 14 can be effectively prevented from being damaged by the protruding pin P. When the shaft protrusion 84 is not formed on the movable internal gear 14, it is preferable that the movable annular slide contact portion 86 has a cutout portion for the protruding pin P, similarly to the fixed internal gear 13.

As described above, each component is a molded product such as resin. In this case, the resin material is preferably a polyacetal resin, a polyamide resin, a polyester resin or a base polymer obtained by blending carbon fibers, whiskers, glass fibers, mica and the like.

Next, another embodiment of each part will be described. FIG. 9 shows another embodiment around the input side case 7 (second embodiment).
Embodiment). In this embodiment, one character groove 91 having a substantially one-character shape in a plan view is formed inside the input side case 7, and the pair of counterbore grooves 24, 24 and the pair of fitting grooves are formed at both ends of the one character groove 91. A pair of deep grooves 92, 92 that also serve as 25, 25 are formed. That is, in this embodiment, the pair of counterbore grooves 24, 24 and the pair of fitting grooves 25, 25 are arranged in an overlapping manner. in this case,
Each deep groove 92 has a cross-sectional shape that prioritizes the shape into which the fitting protrusion 77 of the fixed internal gear 13 fits.

Since the counterbore groove 24 and the fitting groove 25 are also used in this manner, the number of grooves formed in the input side case 7 can be reduced and the structure of the input side case 7 can be simplified. can do. This also facilitates the structure of the mold for the integral molding and the die cutting, so that the input side case 7 can be easily formed. Both grooves 24,
It is also possible to use the extra space as a storage space for other parts by using the doubled space 25.

10 to 13 show another embodiment (third embodiment) around a carrier. This embodiment facilitates the assembling of the carrier 12 of each planetary gear 11 in consideration of each component being ultra-compact. The carrier 12 may have a two-divided structure as described above, but in this embodiment, an integrated structure is used.

As shown in FIGS. 10 and 11, in this embodiment, the carrier 12 has the input side bearing portion 101.
Output bearing 102 and both bearings 101, 10
Three columnar connecting portions 103, 103, 103 for connecting 2
And are molded integrally with resin or the like. In addition, three bearing holes (54, 6) of each bearing portion 101, 102
The portion corresponding to 5) is a "U" -shaped 3 formed by cutting in the radial direction from the outer peripheral surfaces of the bearing portions 101, 102.
Two outward bearing grooves 104a and 104b are formed.
That is, the planetary gears 11 are mounted on the carrier 12 from the outer side in the radial direction (direction substantially orthogonal to the axial direction).

As a result, the planetary gear 11 can be easily assembled to the carrier 12, and the carrier 12 itself can be integrally formed. However, with such a configuration, the planetary gear 11 has a meshing intersection between the sun gear 10, the fixed internal gear 13, and the movable internal gear 14 that mesh with the planetary gear 11. However, in a stable rotation state, rattling does not pose a problem due to the rotation balance of each gear. Therefore, in this embodiment, at least one of the support shaft portions 105a and 105b of each planetary gear 11 can be positioned.

That is, one support shaft portion 105b pivotally supported by the output side bearing portion 102 of each planetary gear 11 extends so as to project from the output side bearing portion 102, while the end of the movable internal gear 14 is extended. The support shaft portion 1 is provided on the inner surface of the face wall portion 83.
A concave annular guide groove (annular guide portion) 107 into which the protruding portion 106 of 05b is inserted is formed. In this case, although the annular guide groove 107 can be configured as a shallow groove, the axis of the sun gear (or carriage 12) 10 and the axis of the planetary gear 11 can be maintained in parallel (cantilever support). It is preferable that one of the support shafts 105b is a deep groove whose position can be regulated.

As the carrier 12 rotates, the planetary gear 1
When 1 circles (revolves) around the sun gear 10,
The protruding portion 106 of the support shaft portion 105b is formed in the annular guide groove 10.
Guided by 7 and make a circular motion. As a result, each planetary gear 1
1 is a position-regulated, sun gear 10, fixed internal gear 1
3 and the movable internal gear 14 are kept in good mesh. Although not particularly shown, the other support shaft portion 105a of each planetary gear 11 is also projected from the input side bearing portion 101,
The protruding portion may be slidably engaged with an annular guide portion such as a step portion or a groove portion formed on the fixed internal gear 13.

FIG. 12 shows a first modification of the third embodiment. In this modification, the input side bearing portion 101 has three "U" -shaped outwardly extending radially from the outer peripheral surface thereof. While the bearing groove 104a is formed, the output side bearing portion 1
02, three "U" -shaped inward bearing grooves 108 extending in the radial direction from the inner peripheral surface (circular opening 109) are formed. In addition, a ring (forming a circular shaft hole 63 inside) 110 for preventing the support shaft portion 105b mounted in the inward bearing groove 108 from coming off is fitted into the circular opening 109. In this case, this one support shaft portion 105b is positioned by the ring 110, and thereby the axis line of the sun gear (or carriage 12) 10 and the axis line of the planetary gear are maintained in parallel (cantilevered support), preferable.

In this structure, the planetary gear 11 is tilted at an angle.
By holding the support shaft portions 105a and 105b at the open portions of the outward bearing groove 104a and the inward bearing groove 108 to return the inclination of the planetary gear 11 to the support shaft portions 105a and 105b. Both bearing grooves 104
a, 108. Then, the ring 110 is attached to the circular opening 109, and the attachment of each planetary gear 11 to the carrier 12 is completed. The outward bearing groove 104a of the input side bearing portion 101 may be an inward bearing groove. Further, as described above, the other supporting shaft portion 105a may be extended and the protruding portion thereof may be guided by the fixed internal gear 13.

FIG. 13 shows a second modification of the third embodiment. In this modification, the input side bearing portion 101 is formed with three bearing holes 112 having inclined guide portions 112a, while the output is provided. The side bearing portion 102 has three "U" -shaped outward bearing grooves 1 radially extending from the outer peripheral surface thereof.
04b is formed. The inclined guide portion 112a is formed by slightly inclining a substantially half portion of the bearing hole 112 on the planetary gear 11 side outward in the radial direction. Also in this case, the one support shaft portion 105a is positioned by the bearing hole 112, and the sun gear (or the carriage 12) is thereby positioned.
It is preferable that the axis of 10 and the axis of the planetary gear 11 are kept parallel (cantilevered support).

In this structure, the planetary gear 11 is tilted at an angle.
Is held and guided to the inclined guide portion 112a to receive the bearing hole 1
While inserting one support shaft portion 105a into 12, the inclination of the planetary gear 11 is returned to the other support shaft portion 105b.
Is mounted in the outward bearing groove 104b from the side. In addition,
As described above, the other supporting shaft portion 104b may be extended and the protruding portion thereof may be guided by the movable internal gear 14. It is also possible to form an outward bearing groove in the input side bearing portion 101 and a bearing hole in the output side bearing portion 102. Furthermore, it is also possible to adopt a configuration in which the first modification and the second modification are combined.

Next, FIGS. 14 and 18 show another embodiment (fourth embodiment) around the fixed internal gear 13. In this embodiment, when an external force acts on the output side,
In particular, it is to prevent the motor 2 from being overloaded,
Some of the components are slip-rotating.

As shown in FIGS. 14 and 15, in this embodiment, the fixed internal gear 13 is not provided with the above-mentioned fitting projection 77, and the output side case (case 2) 8 is provided.
Between the fixed internal gear 13 and the internal gear 13 is a torque limiter.
The ring 121 is interposed. On the outer peripheral surface of the fixed internal gear 13, an annular mounting groove 122 having a "U" -shaped cross section is formed near the input side case 7, and the O-ring 121 is mounted in the annular mounting groove 122. There is. When the output side case 8 is snapped in with the O-ring 121 mounted on the fixed internal gear 13, the O-ring 12 having a circular cross section is formed.
1 is crushed somewhat.

In this configuration, when an external force acts on the output side and a fixed torque (high load state) acts on the fixed internal gear 13, the fixed internal gear 1 resists the frictional force of the O-ring 121.
3 slip-rotates so that an overload condition can be avoided. As a result, damage to each component gear and the motor 2
The image sticking can be effectively prevented. The annular mounting groove 122 in which the O-ring 121 is mounted may be formed on the inner peripheral surface of the output side case 8. Further, although not particularly shown, in the structure in which the input side case 7 accommodates the fixed internal gear 13, the O-ring 121 includes the input side case 7
It goes without saying that it is interposed between the fixed internal gear 13 and the fixed internal gear 13.

FIG. 16 shows a first modification of the fourth embodiment. In this modified example, instead of the above-mentioned O-ring 121, an annular projection portion 124 exhibiting a spring property is integrally formed on the outer peripheral surface of the fixed internal gear 13. Also in this case, when an external force acts on the output side and a fixed torque (high load state) acts on the fixed internal gear 13, the annular protrusion 124
The fixed internal gear 13 slips and rotates against the frictional force of
It is designed to avoid overload conditions. Further, similarly to the above, the annular protruding portion 124 may be formed on the inner surface of the output side case 8.

FIG. 17 shows a second modification of the fourth embodiment. In this modification, instead of the O-ring 121, the coiled spring 12 is provided on the outer peripheral surface of the fixed internal gear 13.
6 is wound up. In this case, the spring 126 has both ends thereof locked in the slit 127 formed in the output side case 8 in a rotationally stopped state. In addition, the spring 12 is adjusted so that the slip rotation direction is the direction in which the spring 126 is wound and tightened.
6 are provided. In this case, when an external force acts on the output side and a fixed torque (high load state) acts on the fixed internal gear 13, the fixed internal gear 13 slips and rotates against the frictional force of the wound spring 126, It is designed to avoid overload conditions.

FIG. 18 shows a third modification of the fourth embodiment. In this modification, instead of the movable gear forming portion 82 of the movable internal gear 14, this portion is constituted by a movable friction wheel 128, and instead of the small gear forming portion 43 of each planetary gear 11, this portion is a small friction wheel 129. It is composed of, so-called mechanical friction wheels rolling contact with each other (friction transmission mechanism). Also in this case, when an external force acts on the output side and a fixed torque (high load state) acts on the fixed internal gear 13, both friction wheels 128 and 129 slip rotate to avoid an overload state. Has become. Needless to say, other gears that mesh with each other, for example, the fixed internal gear 13 and the planetary gear 11 may be friction wheels.

[0063]

As described above, according to the small speed reducer of the present invention and the geared motor having the same, it is possible to avoid an overload state with a simple structure and to position the O-ring in the annular groove. Can be kept constant and the shaft deviation of the fixed internal gear during slip rotation can be prevented, so that the slip-out torque during slip rotation can be maintained stable and an overload state can be appropriately avoided. You can

[Brief description of drawings]

FIG. 1 is an external perspective view of a geared motor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the geared motor according to the embodiment.

FIG. 3 is a vertical cross-sectional view of the small reduction gear according to the embodiment.

FIG. 4 is an exploded perspective view of an input side case and a fixed internal gear of the small reduction gear according to the embodiment.

FIG. 5 is an exploded perspective view of an output side case and a movable internal gear of the small reduction gear according to the embodiment.

FIG. 6 is an exploded perspective view of a carrier and a planetary gear of the small reduction gear according to the embodiment.

FIG. 7 is an exploded perspective view of a carrier, a planetary gear, and a movable internal gear of the compact speed reducer according to the embodiment.

FIG. 8 is an exploded perspective view of a fixed internal gear of the small reduction gear according to the embodiment.

FIG. 9 is an exploded perspective view of an input side case and a fixed internal gear of a compact speed reducer according to a second embodiment.

FIG. 10 is a vertical cross-sectional view of a small reducer according to a third embodiment.

FIG. 11 is an exploded perspective view around a carrier of a small speed reducer according to a third embodiment.

FIG. 12 is an exploded perspective view around a carrier of a small speed reducer according to a first modified example of the third embodiment.

FIG. 13 is an exploded perspective view around a carrier of a small speed reducer according to a second modification of the third embodiment.

FIG. 14 is a vertical cross-sectional view of a small reducer according to a fourth embodiment.

FIG. 15 is an exploded perspective view of an input side case and a fixed internal gear of a small reducer according to a fourth embodiment.

FIG. 16 is a vertical cross-sectional view of a small speed reducer according to a first modification of the fourth embodiment.

FIG. 17 is a vertical cross-sectional view of a small reducer according to a second modification of the fourth embodiment.

FIG. 18 is a vertical cross-sectional view of a small reducer according to a third modified example of the fourth embodiment.

[Explanation of symbols]

1 Geared Motor 2 Motor 2a Spindle 2c End Face 3 Small Reducer 4 Case 5 Planetary Gear Mechanism 7 Input Side Case 8 Output Side Case 10 Sun Gear 11 Planetary Gear 12 Carrier 12a Input Side Piece 12b Output Side Piece 13 Fixed Internal Gear 14 Internal gear 15 Output shaft 24 Counterbore groove 25 Fitting groove 31 Sliding opening 41 Gear body 42a Support shaft portion 42b Support shaft portion 51 Bearing portion 52 Columnar connecting portion 54 Bearing hole 56 Annular protrusion 61 Bearing portion 62 Columnar connecting portion 63 Circular shaft hole 64 Annular convex portion 65 Bearing hole 71 Fixed gear forming portion 73 Fixed side annular sliding contact portion 74 Notch portion 76 Annular step 77 Fitting protrusion 81 Gear body 82 Movable gear forming portion 83 End face wall portion 84 Shaft protrusion 86 Movable side annular sliding contact part 87 End face wall step part 92 Deep groove 101 Input side bearing part 102 Output side bearing part 104a Outward Bearing groove 104b Outward bearing groove 105a Support shaft portion 105b Support shaft portion 106 Projection portion 107 Annular guide groove 108 Inward bearing groove 109 Circular opening 110 Ring 112 Bearing hole 112a Inclined guide portion 121 O
Ring 122 Annular mounting groove 124 Annular projection 126 Spring 128 Moving friction wheel 129 Small friction wheel P Projecting pin

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 17/00 G03B 17/00 W H02K 7/116 H02K 7/116 F term (reference) 2H020 MC22 MC32 MC33 3J027 FA50 FB28 FB40 GC13 GC24 GC26 GD04 GD07 GD12 GE11 3J062 AA33 AA36 AB06 CF04 CF06 3J063 AA40 AB12 AC01 BB15 BB50 CA01 CB05 CD41 CD70 5H607 AA01 AA12 BB01 BB04 BB14 CC03 DD19 EE33

Claims (6)

[Claims] 1. A sun gear on the input side, a planetary gear that meshes with the sun gear, a carrier that rotatably supports the planetary gear and revolves around the sun gear, and fixed internal teeth that mesh with the planetary gear. A planetary gear mechanism comprising a gear and an output-side movable internal gear that meshes with the planetary gear,
A small size which is provided in the case and has a torque limiter between the fixed internal gear and the case, which allows slip rotation of the fixed internal gear when the planetary gear mechanism reaches a high load state. In the speed reducer, an annular groove having a concave cross section is formed on the outer peripheral surface of the fixed internal gear or the inner peripheral surface of the case, and the torque limiter is composed of an O-ring mounted in the annular groove. Small reducer characterized by. 2. A sun gear on the input side, a planetary gear that meshes with the sun gear, a carrier that rotatably supports the planetary gear and revolves around the sun gear, and fixed internal teeth that mesh with the planetary gear. A planetary gear mechanism comprising a gear and an output-side movable internal gear that meshes with the planetary gear,
A small size which is provided in the case and has a torque limiter between the fixed internal gear and the case, which allows slip rotation of the fixed internal gear when the planetary gear mechanism reaches a high load state. In the speed reducer, the small-sized speed reducer is characterized in that the torque limiter is formed of a protrusion having a spring property formed on an outer peripheral surface of the fixed internal gear or an inner peripheral surface of the case. 3. A sun gear on the input side, a planetary gear that meshes with the sun gear, a carrier that rotatably supports the planetary gear and revolves around the sun gear, and fixed internal teeth that mesh with the planetary gear. A planetary gear mechanism comprising a gear and an output-side movable internal gear that meshes with the planetary gear,
A small size which is provided in the case and has a torque limiter between the fixed internal gear and the case, which allows slip rotation of the fixed internal gear when the planetary gear mechanism reaches a high load state. In the speed reducer, the torque limiter is a small speed reducer having an end fixed to the case and a spring wound around the outer peripheral surface of the fixed internal gear. 4. A sun gear on the input side, a planetary gear that meshes with the sun gear, a carrier that rotatably supports the planetary gear and revolves around the sun gear, and fixed internal teeth that mesh with the planetary gear. In a small reduction gear provided with a planetary gear mechanism consisting of a gear and an output-side movable internal gear that meshes with the planetary gear, the sun gear, the planetary gear, the fixed internal gear and the movable internal gear Among them, a small speed reducer characterized in that any two gears that mesh with each other are constituted by two friction wheels that are in rolling contact with each other instead of the two gears. 5. The small reduction gear according to claim 4, wherein the arbitrary two gears are the movable internal gear and the planetary gear that mesh with each other. 6. A geared motor comprising: the small reducer according to claim 1; and a motor in which the small reducer is directly connected to a main shaft.