JP2001099242A - Small-sized planetary gear drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processing accuracy of an inner gear in an inner periphery of a housing. SOLUTION: This small-sized planetary gear drive is constituted by dividing a housing into an inner case in which an inner gear is formed and an output shaft housing storing an output shaft. Accordingly, both ends in an axial direction of the inner case are made open thereby processing of the inner gear is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a small planetary gear device.

[0002]

2. Description of the Related Art A conventional small planetary gear device used for a micromachine or the like is configured as shown in FIG.

The small planetary gear set shown in FIG.
An example of a column is shown. That is, the conventional small planetary gear device 1
Is a housing 2 comprising a large-diameter cylindrical portion 2a for accommodating a planetary gear mechanism and a small-diameter cylindrical portion 2b for accommodating an output shaft and a bearing.
It has. An internal gear 3 is provided on the inner peripheral surface of the large-diameter cylindrical portion 2a.

A plurality of projections 2d having mounting holes 2d 'for mounting the small planetary gear device 1 to a device such as a micromachine are provided on the outer periphery of the small diameter cylindrical portion 2b.

A disc-shaped pedestal 4 is attached to the opening surface of the large-diameter cylindrical portion 2a of the housing 2, and a central hole 4 of the pedestal 4 is provided.
An input shaft (drive shaft of the motor M) 5 is inserted inward from a, and an input gear 6 is fixed to an inner end of the input shaft 5.

On the pedestal 4 side, a plurality of screw holes 4b are provided, for example, near the distal end of the large-diameter cylindrical portion 2d of the housing 2 to fix the motor M.

The base of the output shaft 8 is rotatably accommodated in the small-diameter cylindrical portion 2b of the housing 2 by a plurality of (for example, two) bearings 7.

The two bearings 7, 7 are accommodated so as to sandwich the annular projecting portion 2c of the small-diameter cylindrical portion 2b, and the outer portions of the two bearings 7, 7 are held so that the output shaft 8 does not move in the axial direction. , Two E-rings 8a, 8a are fitted into annular grooves 8b, 8b provided on the output shaft 8.

At the center of the inner end of the output shaft 8, a fitting hole 9 is provided.
The output plate 9 having a is press-fitted and fixed. The output plate 9 is provided with a plurality (for example, three) of the planetary shafts 1 at equal intervals in the circumferential direction.
0 is fixed, and a planetary gear 11 having the same number of teeth is rotatably fitted to each planetary shaft 10.

Each planetary gear 11 meshes with the internal gear 3 on the inner periphery of the large-diameter cylindrical portion 2a of the housing 2 and also meshes with the central sun gear 12 while rotating inside the internal gear 3 while rotating. Revolves around the sun gear.

The sun gear 12 is located between the inner end of the input shaft 5 and the inner end of the output shaft 8, and is fixed to a central fitting hole 13 a of the sun plate 13.

A plurality of (for example, three) planetary shafts 14 are fixed to the sun plate 13 at equal intervals in the circumferential direction.
, Planetary gears 15 having the same number of teeth are rotatably fitted.

Each planetary gear 15 meshes with the internal gear 3 and also meshes with the central input gear 6, and revolves around the input gear 6 while rotating inside the internal gear 3.

[0014]

However, in the conventional small planetary gear device having such a structure, (1) the internal gear 3 is formed on the inner periphery of the large-diameter cylindrical portion 2a of the housing 2. , Stepped housing 2
In the large-diameter cylindrical portion 2a, which is a part of the above, processing can be performed only from one side of the opening, so that highly accurate internal tooth processing is extremely difficult. For this reason, the molding accuracy of the gears is poor, and the accuracy of meshing with the planetary gears 11 and 15 is also poor.
There were inconveniences, such as poor transmission efficiency to 1 and 15 and noise.

(2) The axial movement of the output shaft 8 is prevented by the E-ring 8a. However, in this method, it is impossible to reduce the backlash in the axial direction of the output shaft 8 to zero. For this reason, rattling is prevented by interposing a washer (not shown) between the E-ring 8a and the bearing 7, but such a method of adjusting while interposing the washer requires a lot of time and labor. Costly, which was a factor of high cost.

(3) The planetary gear device is required to be ultra-miniaturized, and therefore the output shaft 8 is also very thin. However, conventionally, the output shaft 8 has a straight shape, and as described above,
Since the force at the time of press-fitting was received at the tip of the output shaft 8,
If the output shaft 8 is long, it may bend, and the output shaft 8 cannot be made too long.

(4) The planetary gears 11 and 15 meshing with the internal gear 3, the sun gear 12, and the input gear 6 have thicknesses of each planet shaft 1
Although the thickness of each of the planetary gears 11 and 15 is slightly distorted in the axial direction, the thickness of each of the planetary gears 11 and 15 is slightly greater than the thickness of the planetary gears 11 and 15. Therefore, it is difficult to increase the accuracy of meshing with the internal gear 3, the sun gear 12, and the input gear 6, and there is a possibility that rotation failure may occur.

(5) Since a mounting structure such as a screw hole is required for mounting the motor and for mounting the planetary gear device 1, the outer shape becomes larger, the size becomes longer, and the size becomes smaller. Was hindered.

An object of the present invention is to provide a small planetary gear device that solves these problems.

[0020]

In order to achieve the above object, according to the first aspect of the present invention, a planetary gear mechanism is provided in a housing and provided on a pedestal side fixed to one end of the housing in the axial direction. A small planetary gear device that transmits the rotation of the input shaft to the output shaft via the planetary gear mechanism,
The housing is divided into an internal gear case having an internal gear formed therein and an output shaft housing accommodating the output shaft.

Since the internal gear case is divided into the internal gear case and the output shaft housing, the internal gear case is open on both sides in the axial direction. For example, various high-precision processing methods, such as broaching and metal forming, can be performed. As a result, the rotation transmission to the planetary gears is also high-precision, the deceleration efficiency is increased, and noise is hardly generated.

According to a second aspect of the present invention, a cylindrical fixed bush is fixed to the output shaft so as to contact the outer end of the inner race of the bearing of the output shaft. With this configuration, rattling in the axial direction of the output shaft hardly occurs.

According to a third aspect of the present invention, a large diameter portion is provided on the output shaft, and the large diameter portion is located between an output plate fixed to the output shaft and a bearing of the output shaft. And

With this configuration, the stress applied when the output plate is press-fitted and fixed to the output shaft can be received by the large-diameter portion, and even if the output shaft is thin and long, the bending at the time of press-fitting can be prevented. As well as acting as a stopper.

According to a fourth aspect of the present invention, an annular step is provided at an intermediate portion of the planetary shaft of the planetary gear mechanism, and the thickness of the planetary gear attached to the planetary shaft is substantially equal to the thickness of the annular step. It has been reduced by just that much.

In the case of a planetary gear having a large thickness, it is difficult to improve the meshing accuracy with the internal gear if there is a small amount of distortion in the axial direction. When the thickness is reduced, the influence of the distortion in the axial direction is reduced, and the accuracy of the engagement can be increased. Further, even if the thickness is small, it is possible to prevent the annular step portion from tilting in the sideward falling direction.

According to a fifth aspect of the present invention, a planetary gear meshing with an input gear fixed to the input shaft of the planetary gear mechanism is located close to the pedestal.

As described above, since the planetary gear meshing with the input gear is located on the pedestal side, the planetary gear meshes with the root of the input gear fixed to the input shaft of the motor as close to the motor as possible. When the motor is mounted on the pedestal, the motor can be mounted in a state where the engagement between the input gear and the planetary gear has been completed.

According to a sixth aspect of the present invention, the thickness of the pedestal is smaller than the thickness of the input gear fixed to the input shaft.

As described above, since the thickness of the pedestal is smaller than the thickness of the input gear fixed to the input shaft, when the motor is mounted on the pedestal, the input gear fixed to the input shaft of the motor is connected to the planetary gear. The work of meshing with is easy.

According to a seventh aspect of the present invention, a screw portion for mounting is provided on the outer periphery of the housing, and a screw hole for mounting a motor is provided on the pedestal.

Since the housing itself is screwed, the small planetary gear device can be screwed and mounted as it is, and the motor can be directly screwed into the pedestal and mounted on the pedestal. And so on are not required, and the size can be reduced accordingly.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the small planetary gear device of the present invention used for a micromachine or the like.

FIG. 1 shows an example in which the small planetary gear set 20 has two reduction stages. This small planetary gear set 20
Has a housing 22 composed of a large-diameter cylindrical portion 21a for accommodating a planetary gear mechanism and a small-diameter cylindrical portion 21b for accommodating an output shaft and a bearing. An internal gear 23 is formed on the inner peripheral surface of the large-diameter cylindrical portion 21a.

The housing 22 has two parts: a cylindrical internal gear case 24 formed on the inner circumference with the internal gear 23 open at both ends, and an output shaft housing 25 for accommodating an input shaft. , And is divided.

That is, the internal gear case 24 has a cylindrical shape whose both ends in the axial direction are open as described above, and has an internal gear 23 formed on the inner peripheral surface thereof. Annular edge plates 24a, 24b are protruded in the axial direction.

The output shaft housing 25 includes the internal tooth case 24.
A circular dish plate-like portion 26 having an outer shape adapted to fit inside the annular edge plate 24a, and a cylindrical portion 27 having a smaller diameter than the dish plate-like portion 26. 24a, and the annular edge plate 24a is caulked at a plurality of locations, so that the output shaft housing 25 and the internal tooth case 24
Are fixed integrally.

Since the inner tooth case 24 and the output shaft housing 25 are formed separately as described above, the inner tooth case 24 is open on both sides in the axial direction. Various high-precision machining methods, such as broaching, metal forming, etc., are possible for the internal gear 23 of this type. As a result, the rotation transmission to the planetary gears is also highly accurate, the deceleration efficiency is increased, and the noise is also reduced. Less likely to occur.

On the outer periphery of the cylindrical portion 27 of the output shaft housing 25, there is provided a screw portion 28 for screwing into a screw hole of a device such as a micromachine for mounting.

As described above, since the output shaft housing 25 itself is a screw, a small planetary gear device can be screwed and mounted as it is, and a special mounting projection or the like is not required, and the size can be reduced accordingly. it can.

An annular projecting portion 29 is provided substantially at the center of the inner peripheral surface of the cylindrical portion 27 in the axial direction. A disk-shaped pedestal 32 is fitted and fixed in the annular edge plate 24b on the other end side of the internal tooth case 24, and its flange 32a is in a state of abutting against the tip of the annular edge plate 24b.

A cylindrical hole 33 is provided in the center of the pedestal 32, and a screw portion 33a for screwing and mounting the motor is provided on the inner periphery of the hole 33.

As a result, the motor can be directly fixed to the pedestal 32, and a special projection for screwing and mounting parts are not required, so that the size can be reduced accordingly.

When the motor is screwed into the hole 33 and fixed, the drive shaft (input shaft 35) of the motor is inserted in alignment with the center axis of the internal gear case 24.

An input gear 36 is fixed to the input shaft 35. In the cylindrical portion 27 of the output shaft housing 25, the base of the output shaft 38 is rotatably accommodated via two bearings 37, 37 sandwiching the annular protrusion 29.

An output plate 39 having a fitting hole 39a at the center is press-fitted and fixed to the inner end of the output shaft 38. Between the output plate 39 and the inner bearing 37, the output shaft 3
8 has a large-diameter portion 38a.

With this configuration, the force applied when the output plate 39 is press-fitted and fixed to the output shaft 38 can be received by the large-diameter portion 38a. Even if the output shaft 38 is thin and long, the bending at the time of press-fitting is possible. Can be prevented.

The large-diameter portion 38a serves as a stopper for the output plate 39 and the inner bearing 37. The output plate 39 and the output shaft 38 may be formed integrally.

A cylindrical fixed bush 42 is press-fitted into the output shaft 38 from the outer end, and the large-diameter portion 38a of the output shaft 38 is pressed.
And the inner bearing 37 are in contact with each other, and the fixed bush 42 is in contact with the inner ring of the outer bearing 37.

With this arrangement, the output shaft 38 hardly rattles in the axial direction. Note that a ring-shaped leaf spring (not shown) may be interposed between the fixed bush 42 and the outer bearing 37. Further, the fixed bush 42 may be fixed to the output shaft 38 by screwing.

The output plate 39 is housed in the countersunk hole 26a of the countersunk plate portion 26 of the output shaft housing 25.

A plurality of (for example, three) first planetary shafts 44 are fixed to the output plate 39 at equal intervals in the circumferential direction, and each of the first planetary shafts 44 has the same number of teeth. One planetary gear 45 is rotatably fitted.

Each of the first planetary gears 45 meshes with the internal gear 23 on the inner periphery of the internal gear case 24 and also meshes with the central sun gear 48. Revolves around the gear 48.

The sun gear 48 includes the input gear 36 and the output shaft 3
8 and is press-fitted and fixed in a central fitting hole 49a of a disc-shaped sun plate 49.

A plurality of (for example, three) second planetary shafts 50 are fixed to the sun plate 49 at equal intervals in the circumferential direction.
The second planetary gears 5 having the same number of teeth
1 is rotatably fitted.

Each of the second planetary gears 51 meshes with the internal gear 23 on the inner periphery of the internal gear case 24 and also meshes with the central input gear 36, so that the input is performed while rotating inside the internal gear 23. Revolves around the gear 36.

The second planetary shaft 50 is provided with an annular step portion 50a having a large diameter at the middle portion thereof.
The thickness of the second planetary gear 51 mounted on the second planetary gear 5 is reduced by the thickness of the annular step 50a, and the thickness of the second planetary gear 5 is reduced by the thickness of the annular step 50a.
The position 1 is on the pedestal 32 side.

In the case of a planetary gear having a large thickness, it is difficult to improve the meshing accuracy with the internal gear 23 if there is a small amount of distortion in the axial direction. When the thickness is reduced, the influence of the distortion in the axial direction is reduced, and the accuracy of the engagement can be improved. Further, even when the thickness is small, the annular step portion 50a can prevent the inclination in the sideward falling direction.

Since the second planetary gear 51 is located on the side of the pedestal 32 by the thickness of the annular step portion 50a, the input gear 36 fixed to the input shaft 35 of the motor should be as close as possible to the root portion on the motor side. Since the second planetary gears 51 mesh with each other, when the motor is mounted on the pedestal 32, the motor can be mounted in a state where the input gear 36 and the second planetary gears 51 have completely meshed.

When the input gear 36 is fixed to the motor body with almost no gap, the thickness of the pedestal 32 (at least the thickness of the hole 33) is adjusted by the second planetary gear 5.
When the motor is mounted on the pedestal 32, the tip of the input gear 36 can be meshed with the second planetary gear 51 before the motor itself comes into contact with the screw portion 33a of the hole 33 by making the thickness smaller than the thickness of the first planetary gear 51. The meshing work can be performed with the motor and screw
It can be easily performed without being hindered by the contact with 3a.

However, if the pedestal 32 is too thin, the length of the screw portion 33a may be insufficient, making it difficult to mount the motor or reducing the strength. Of the second planetary gear 51 may be slightly smaller than the thickness of the second planetary gear 51. For example, the thickness of the pedestal 32 may be about 0.8 times the thickness of the second planetary gear 51. Is appropriate.

The embodiment of the present invention has been described above.
The present invention is not limited to the configuration of this embodiment, and it is needless to say that various deformations can be made in each part. For example, a screw surface for mounting is formed on the outer periphery of the internal tooth case 24 forming the housing 22. May be.

A lead screw 52 is provided on the output shaft 38 as shown in FIG.
May be engaged with a pinion (not shown). Also, the diameter of the distal end side of the portion of the output shaft 38 to which the fixed bush 42 is fixed may be slightly smaller so that the fixed bush 42 is easily press-fitted. Although the bearing 37 is exemplified as the bearing, an oil-impregnated bearing may be used.

[0064]

As described above, according to the first aspect of the present invention,
In the small planetary gear device, a planetary gear mechanism is provided in the housing, and the rotation of the input shaft provided on the pedestal side fixed to one end of the housing in the axial direction is transmitted to the output shaft via the planetary gear mechanism. The housing is divided into an internal gear case having an internal gear formed therein and an output shaft housing accommodating the output shaft.

Since the internal gear case is divided into the internal gear case and the output shaft housing, the internal gear case is open on both sides in the axial direction. For example, various high-precision processing methods, such as broaching and metal forming, can be performed. As a result, the rotation transmission to the planetary gears is also high-precision, the deceleration efficiency is increased, and noise is hardly generated.

According to a second aspect of the present invention, a cylindrical fixed bush is fixed to the output shaft so as to contact the outer end of the inner race of the bearing of the output shaft. With this configuration, rattling in the axial direction of the output shaft hardly occurs.

According to a third aspect of the present invention, a large-diameter portion is provided on the output shaft, and the large-diameter portion is located between an output plate fixed to the output shaft and a bearing of the output shaft. And

With this configuration, the stress applied when the output plate is press-fitted and fixed to the output shaft can be received by the large-diameter portion, and even if the output shaft is thin and long, bending at the time of press-fitting can be prevented. As well as acting as a stopper.

According to a fourth aspect of the present invention, an annular step is provided at an intermediate portion of the planetary shaft of the planetary gear mechanism, and the thickness of the planetary gear attached to the planetary shaft is substantially equal to the thickness of the annular step. It has been reduced by just that much.

In the case of a planetary gear having a large thickness, it is difficult to improve the meshing accuracy with the internal gear if there is a small amount of distortion in the axial direction. When the thickness is reduced, the influence of the distortion in the axial direction is reduced, and the accuracy of the engagement can be increased. Further, even if the thickness is small, it is possible to prevent the annular step portion from tilting in the sideward falling direction.

According to a fifth aspect of the present invention, the planetary gear meshing with the input gear fixed to the input shaft of the planetary gear mechanism is located close to the pedestal.

As described above, since the planetary gear meshing with the input gear is located on the pedestal side, the planetary gear meshes with the root portion of the input gear fixed to the input shaft of the motor as close to the motor as possible. When the motor is mounted on the pedestal, the motor can be mounted in a state where the engagement between the input gear and the planetary gear has been completed.

According to a sixth aspect of the present invention, the thickness of the pedestal is smaller than the thickness of the input gear fixed to the input shaft.

As described above, since the thickness of the pedestal is smaller than the thickness of the input gear fixed to the input shaft, when the motor is mounted on the pedestal, the input gear fixed to the input shaft of the motor is connected to the planetary gear. The work of meshing with is easy.

According to a seventh aspect of the present invention, a mounting screw portion is provided on the outer periphery of the housing, and a screw hole for mounting a motor is provided on the pedestal.

As described above, since the housing itself is screwed, the small planetary gear device can be screwed and mounted as it is, and the motor can be screwed as it is to the pedestal and mounted on the pedestal. And so on are not required, and the size can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional small planetary gear device.

[Explanation of symbols]

 Reference Signs List 20 small planetary gear device 22 housing 23 internal gear 24 internal gear case 25 output shaft housing 28 screw surface 32 pedestal 35 input shaft 36 input gear 37 bearing 38 output shaft 39 output plate 42 fixed bush 44 first planetary shaft 45 first Planetary gear 46 annular spacer 48 sun gear 49 sun plate 50 second planetary shaft 50a annular step 51 second planetary gear

Claims (7)

[Claims] 1. A planetary gear mechanism is provided in a housing,
In a small planetary gear device for transmitting rotation of an input shaft provided on a pedestal side fixed to one end in an axial direction of the housing to an output shaft via the planetary gear mechanism, the housing is formed with an internal gear. A small planetary gear device, which is divided into an internal gear case and an output shaft housing that houses the output shaft. 2. A planetary gear mechanism is provided in a housing,
In a small planetary gear device for transmitting rotation of an input shaft provided on a pedestal side fixed to one end in an axial direction of the housing to an output shaft via the planetary gear mechanism, an outer end of an inner ring of a bearing of the output shaft. A small planetary gear device characterized in that a cylindrical fixed bush is fixed to the output shaft so as to contact the output shaft. 3. A planetary gear mechanism is provided in a housing,
In a small planetary gear device for transmitting rotation of an input shaft provided on a pedestal side fixed to one end in the axial direction of the housing to an output shaft via the planetary gear mechanism, a large-diameter portion is provided on the output shaft, A small planetary gear device wherein a large diameter portion is formed as a stopper located between an output plate fixed to the output shaft and a bearing of the output shaft. 4. A planetary gear mechanism is provided in a housing,
In a small planetary gear device that transmits the rotation of an input shaft provided on a pedestal side fixed to one end in the axial direction of the housing to an output shaft via the planetary gear mechanism, an intermediate portion of the planetary shaft of the planetary gear mechanism. A small planetary gear device having an annular step portion, wherein the thickness of a planetary gear mounted on the planet shaft is reduced by substantially the thickness of the annular step portion. 5. A planetary gear mechanism is provided in a housing,
A small planetary gear device that transmits rotation of an input shaft provided on a pedestal side fixed to one end in the axial direction of the housing to an output shaft via the planetary gear mechanism, wherein the planetary gear mechanism is fixed to the input shaft. A planetary gear meshing with the input gear is positioned close to the pedestal. 6. A planetary gear mechanism is provided in a housing,
In a small planetary gear device that transmits rotation of an input shaft provided on a pedestal side fixed to one end in the axial direction of the housing to an output shaft via the planetary gear mechanism, the thickness of the pedestal is adjusted to the input shaft. A small planetary gear device characterized in that the thickness is smaller than the thickness of a fixed input gear. 7. A planetary gear mechanism is provided in a housing,
In a small planetary gear device for transmitting rotation of an input shaft provided on a pedestal side fixed to one end in the axial direction of the housing to an output shaft via the planetary gear mechanism, a mounting screw portion is provided on an outer periphery of the housing. A small planetary gear device, wherein a screw hole for mounting a motor is provided on the pedestal.