WO2020110897A1

WO2020110897A1 - Small reduction gear

Info

Publication number: WO2020110897A1
Application number: PCT/JP2019/045603
Authority: WO
Inventors: 小川　隆雄; 清水　猛; 樹哉岸野
Original assignee: 日本電産株式会社
Priority date: 2018-11-30
Filing date: 2019-11-21
Publication date: 2020-06-04

Abstract

A small reduction gear 1 includes an input gear 33, a first planetary carrier 42, and a first planetary gear 44 which are formed by a molded body of a resin composition containing, in a base resin, an inorganic whisker that serves as a functional expression component, the combined content of the base resin and the inorganic whisker in the resin composition being 99.5% by weight or more. Or, the foregoing are formed by a molded body of a resin composition containing an inorganic whisker and a lubricant that serve as functional expression components in a base resin, the combined content of the base resin, the inorganic whisker, and the lubricant in the resin composition being 99.5% by weight or more, and the content of the lubricant being 1% by weight or more. The input gear 33 and the first planetary carrier 42, or the input gear 33 and the first planetary gear 44, are formed by the same material, and the first planetary gear 33 and the first planetary carrier 42 are formed by different materials.

Description

Small reducer

The present invention relates to a small reducer mounted in, for example, a small and thin electronic device.

As a small reducer using a planetary gear mechanism, for example, a small reducer described in Patent Document 1 is known. This small reduction gear is composed of a fixed internal gear, a movable internal gear, a planetary gear meshed with the fixed internal gear and the movable internal gear, and a planetary gear held by a holder body and a holder retainer, and a motor meshing with the planetary gear. In a small speed reducer including a sun gear directly connected to a shaft, a support beam provided in a holder body and a guide portion provided at a contact portion between a fixed internal gear and a movable internal gear. ‥

Patent Document 2 discloses that components such as a sun gear and a planetary gear in a small reduction gear are integrally molded products such as resin.

Japanese publication: Japanese Patent Laid-Open No. 4-366460 Japanese Patent Publication: Japanese Patent Laid-Open No. 2003-130145

In the small speed reducer of Patent Document 1, some or all of the components are made of synthetic resin, and the low friction coefficient of the synthetic resin improves gear transmission efficiency and the like. As a synthetic resin material, it is illustrated that a basic resin such as a polyacetal resin or a polyamide resin contains carbon fiber, glass fiber or the like. ‥

Patent Document 2 describes that a polyacetal resin, a polyamide resin, and a polyester resin are used as a resin material, and carbon fibers, whiskers, glass fibers, mica, and the like are mixed using these as a base polymer. ‥

However, even though the conventional resin material configuration described above can reduce the friction coefficient due to the base resin, when a micro gear is molded from the resin material, the surface roughness of the gear is such that the gear unit of the speed reducer is easy to assemble. The effect on the meshing of gears and gears cannot be ignored. As a result, there arises a problem that the transmission efficiency of the gear is reduced. ‥

The present invention has been made in view of the above problems, and an object of the present invention is to provide a compact speed reducer that is compact and highly accurate and that has improved moldability, durability, dimensional accuracy, wear resistance, and the like. ..

As one means for achieving the above object and solving the above problems, the present invention has the following configurations. That is, an exemplary invention of the present application is a small reducer that reduces the power from an input shaft and transmits the power to an output shaft, and includes a casing and an annular first first inner peripheral surface of the casing. An internal gear, an input gear connected to the input shaft, a first rotating shaft portion arranged coaxially with the input shaft in the casing, and a sun gear rotating together with the first rotating shaft portion, A first planetary carrier rotatable about the first rotation shaft portion; a plurality of first planetary gears rotatably supported by the first planetary carrier and meshing with the input gear and the first internal gear; A second rotating body rotatable by the sun gear, wherein the input gear, the first planet carrier, and the first planet gear are made of a thermoplastic resin as a base resin, and as a predetermined functional expression component. Of the resin composition containing inorganic whiskers, the total content of the base resin and the inorganic whiskers in the resin composition is 99.5% by weight or more, or a thermoplastic resin is used. Formed by a molded body of a resin composition containing a base resin and an inorganic whisker as a predetermined functional expression component and a lubricant, and a content rate of the base resin, the inorganic whisker and a lubricant in the resin composition in combination. Is 99.5% by weight or more and the lubricant is contained by 1% by weight or more, the input gear and the first planetary carrier are formed of the same material, and the first planetary gear is the input gear and It is characterized in that it is made of a material different from that of the first planet carrier.

According to the present invention, it is possible to provide a compact speed reducer that is compact and highly accurate and has improved moldability, durability, dimensional accuracy, wear resistance, and the like.

FIG. 1 is a vertical cross-sectional view of a small reducer according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view showing the configuration of a small reducer according to an exemplary embodiment of the present invention. FIG. 1 shows a cross section of a small speed reducer 1 (hereinafter, also simply referred to as a speed reducer) including a central axis J1. ‥

The reduction gear 1 includes a casing 2, an input unit 3, a first rotating body 4, a second rotating body 6, a first internal gear 5, a second internal gear 7, an input shaft 8, and an output shaft 9. And a motor 15 directly connected to the input shaft 8. The input shaft 8 is also the motor shaft of the motor 15. The speed reducer 1 has a planetary gear mechanism having a two-stage configuration of a first rotating body 4 and a second rotating body 6, and is formed with a volume of 5 mm in width, 5 mm in depth, and 20 mm in height or less, for example. ‥

<Casing> The casing 2 has a substantially cylindrical shape centered on the central axis J1. The input unit 3, the first rotating body 4, a part of the second rotating body 6, the first internal gear 5, and the second internal gear 7 are housed inside the casing 2. The input unit 3 is rotatably supported by the casing 2 about the central axis J1. Similarly, the first rotating body 4 and the second rotating body 6 are also rotatably supported by the casing 2 about the central axis J1. ‥

The casing 2 has a substantially cylindrical shape centered on a central axis J1 that faces the vertical direction in FIG. In the following description, for convenience, the second rotary body 6 side will be described as the upper side and the first rotary body 4 side will be the lower side along the central axis J1. However, the direction of the central axis J1 does not necessarily have to coincide with the gravity direction. Absent. ‥

Further, in the following description, the up-down direction, which is the direction in which the central axis J1 faces, is also referred to as the “axial direction”. Further, in the following description, the circumferential direction centering on the central axis J1 is simply referred to as “circumferential direction”, and the radial direction centering on the central axis J1 is simply referred to as “radial direction”.

<First and Second Internal Gears> The first internal gear 5 has an annular shape centered on the central axis J1. The first internal gear 5 is located outside the first rotating body 4 in the radial direction around the central axis J1. The second internal gear 7 has an annular shape centered on the central axis J1. The second internal gear 7 is located outside the second rotary body 6 in the radial direction around the central axis J1. ‥

The first internal gear 5 is arranged on the inner peripheral surface of the casing 2 on the side where the first rotating body 4 is located (also referred to as the first inner peripheral surface), and the second internal gear 7 is the second rotating body. It is arranged on the side where 6 is located (also called the second inner peripheral surface). The first internal gear 5 and the second internal gear 7 have tooth surfaces on the inner circumference of the casing 2 as described later. ‥

The outer peripheral surface of the first internal gear 5 has a substantially cylindrical shape centered on the central axis J1. The outer peripheral surface of the first internal gear 5 contacts the inner peripheral surface of the casing 2. As a result, the first internal gear 5 is fixed to the casing 2. The first internal gear 5 is fixed to the casing 2 by, for example, intermediate fitting. ‥

In other words, before the first internal gear 5 is fixed to the casing 2, the diameter of the outer peripheral surface of the first internal gear 5 is equal to the diameter of the casing 2 at the site where the first internal gear 5 and the casing 2 are scheduled to contact each other. The diameter is substantially the same as the inner peripheral surface of the. ‥

The first internal gear 5 may be indirectly fixed to the casing 2 via another member, or may be a member which is integrally connected to the casing 2 (integrally molded). ‥

The inner peripheral surface of the first internal gear 5 has a substantially cylindrical shape centered on the central axis J1. The inner peripheral surface of the first internal gear 5 is provided with a plurality of teeth arranged in the circumferential direction. In the following description, the plurality of teeth on the inner peripheral surface of the first internal gear 5 are referred to as “inner peripheral teeth”. ‥

The outer peripheral surface of the second internal gear 7 has a substantially cylindrical shape centered on the central axis J1. The outer peripheral surface of the second internal gear 7 contacts the inner peripheral surface of the casing 2. As a result, the second internal gear 7 is fixed to the casing 2. The second internal gear 7 is fixed to the casing 2 by, for example, intermediate fitting. ‥

In other words, in the state before the second internal gear 7 is fixed to the casing 2, the diameter of the outer peripheral surface of the second internal gear 7 is equal to the diameter of the casing at the site where the second internal gear 7 and the casing 2 are scheduled to contact each other. It is almost the same as the diameter of the inner peripheral surface of 2. ‥

Note that, like the first internal gear 5, the second internal gear 7 may be indirectly fixed to the casing 2 via another member, or may be a member integrally connected (integrally molded) with the casing 2. .. ‥

The inner peripheral surface of the second internal gear 7 has a substantially cylindrical shape centered on the central axis J1. The inner peripheral surface of the second internal gear 7 is provided with a plurality of teeth arranged in the circumferential direction. In the following description, the plurality of teeth on the inner peripheral surface of the second internal gear 7 are referred to as “inner peripheral teeth”. ‥

<Input Unit> The input unit 3 includes an input shaft 31 and an input gear 33. The input shaft 31 has a substantially cylindrical shape or a substantially cylindrical shape centered on the central axis J1. The input gear 33 has a substantially cylindrical shape or a substantially cylindrical shape centered on the central axis J1. That is, the input shaft 31 and the input gear 33 are located coaxially. On the outer peripheral surface of the input gear 33, a plurality of teeth arranged in the circumferential direction are provided. In the following description, the plurality of teeth on the outer peripheral surface of the input gear 33 are referred to as “outer peripheral teeth”. ‥

The input shaft 31 and the input gear 33 are located inside the casing 2. The input gear 33 is connected to the upper end portion of the input shaft 31 that projects upward from the lower surface side of the casing 2. The input gear 33 rotates together with the input shaft 31 inside the casing 2. ‥

The input gear 33 may be indirectly connected to the input shaft 31 via another member, or may be a member which is connected to the input shaft 31 (integrally molded). ‥

<First Rotating Body> The first rotating body 4 includes a first rotating shaft portion 41, a first planetary carrier 42, a plurality of first planetary shaft portions 43, a plurality of first planetary gears 44, and a sun gear 45. including. The first rotation shaft portion 41 has a substantially cylindrical shape or a substantially cylindrical shape with the central axis J1 located at the center thereof. The first rotation shaft portion 41, the first planetary carrier 42, the plurality of first planetary shaft portions 43, and the plurality of first planetary gears 44 are located inside the casing 2. ‥

The first planet carrier 42 has a substantially cylindrical shape with a bottom and a lid whose center is located on the central axis J1. The first rotation shaft portion 41 is connected (projected) to the upper end portion of the first planet carrier 42. The first rotating shaft portion 41 and the first planetary carrier 42 are located coaxially with respect to the central axis J1. ‥

The first rotating shaft portion 41 may be indirectly connected to the first planetary carrier 42 via another member, or may be a member that is connected to the first planetary carrier 42 (integrally molded). .. ‥

Each of the plurality of first planetary shaft portions 43 is a substantially columnar shape that faces the direction along the central axis J1, and is a member having the same shape and the same size. In the following description, the central axis of each first planetary shaft portion 43 is referred to as “first planetary shaft J2”. ‥

The above-mentioned "direction along the central axis J1" means a direction substantially parallel to the axial direction in which the central axis J1 faces, and does not need to be strictly parallel to the axial direction. That is, the first planetary axis J2 of each first planetary shaft portion 43 may be parallel to the central axis J1 or may be inclined by a small angle with respect to the central axis J1. ‥

The upper end of each first planetary shaft portion 43 is fixed to the first planetary carrier 42. As a result, each first planetary shaft portion 43 is non-rotatably fixed to the first planetary carrier 42. The plurality of first planetary shaft portions 43 are positioned radially outward of the input gear 33 at substantially equal angular intervals in the circumferential direction. In the example shown in FIG. 1, the three first planetary shaft portions 43 are arranged at intervals of 120° in the circumferential direction. ‥

The first planetary shaft portion 43 may be indirectly fixed to the first planetary carrier 42 via another member, or may be a member that is connected to the first planetary carrier 42 (integrally molded). .. ‥

The plurality of first planetary gears 44 are arranged circumferentially outside the input gear 33 in the casing 2 in the radial direction, and each of the plurality of first planetary gears 44 is arranged in the casing 2 via the plurality of first planetary shaft portions 43. It is rotatably supported by the carrier 42. In the example shown in FIG. 1, the three first planetary gears 44 are supported by the first planetary carrier 42 via the three first planetary shaft portions 43. The plurality of first planetary gears 44 are arranged at substantially the same positions as the inner peripheral teeth of the input gear 33 and the first internal gear 5 in the axial direction.

The number and arrangement of the first planetary gears 44 and the first planetary shaft portions 43 may be changed as appropriate. ‥

Each of the first planetary gears 44 has a substantially cylindrical shape with the first planetary shaft portion 43 as a rotation axis. The outer peripheral surface of each first planetary gear 44 is provided with a plurality of teeth arranged in the circumferential direction. In the following description, the plurality of teeth on the outer peripheral surface of the first planetary gear 44 are referred to as “outer peripheral teeth”. ‥

The plurality of first planetary gears 44 have the same shape and the same size, and their outer peripheral teeth are engaged with the outer peripheral teeth of the input gear 33 and the inner peripheral teeth of the first internal gear 5. Do (mesh). ‥

Each of the first planetary gears 44 is rotatably supported by the first planetary shaft portion 43 about the first planetary shaft portion 43. That is, each of the plurality of first planetary gears 44 is rotatably supported by the first planetary carrier 42 about the first planetary axis J2 that faces the direction along the central axis J1. ‥

On the other hand, the first planetary carrier 42 is rotatably supported by the first internal gear 5. As described above, since the first internal gear 5 is fixed to the casing 2, the first planet carrier 42 is rotatably supported by the casing 2. ‥

The sun gear 45 is connected to the upper end portion of the first rotating shaft portion 41. The sun gear 45 rotates together with the first rotating shaft portion 41 inside the casing 2. The sun gear 45 may be indirectly connected to the first rotating shaft portion 41 via another member, or may be a member that is connected (integrally molded) with the first rotating shaft portion 41. ‥

<Second Rotating Body> The second rotating body 6 includes a second rotating shaft portion 61, a second planet carrier 62, a plurality of second planetary shaft portions 63, and a plurality of second planetary gears 64. Or a spur gear (not shown) that meshes with the sun gear 45. The second rotation shaft portion 61 has a substantially cylindrical shape or a substantially cylindrical shape with the central axis J1 located at the center thereof. The second rotating shaft portion 61 projects upward from the upper surface of the casing 2 to the outside of the casing 2. The second planet carrier 62, the plurality of second planetary shaft portions 63, and the plurality of second planetary gears 64 are located inside the casing 2. ‥

The second planet carrier 62 has a substantially cylindrical shape with a bottom and a lid whose center is located on the central axis J1. The second rotation shaft portion 61 is connected (projected) to the upper end portion of the second planet carrier 62. The second rotary shaft portion 61 and the second planet carrier 62 are coaxially located with the central axis J1 as the center. ‥

The second rotating shaft portion 61 may be indirectly connected to the second planetary carrier 62 via another member, or may be a member that is connected to the second planetary carrier 62 (integrally molded). .. ‥

Each of the plurality of second planetary shaft portions 63 is a substantially columnar shape that faces the direction along the central axis J1, and is a member having the same shape and the same size. In the following description, the central axis of each second planetary shaft portion 63 is referred to as "second planetary axis J3". ‥

Here again, the “direction along the central axis J1” means a direction substantially parallel to the axial direction to which the central axis J1 faces, and does not need to be strictly parallel to the axial direction. That is, the second planetary axis J3 of each second planetary shaft portion 63 may be parallel to the central axis J1 or may be inclined by a small angle with respect to the central axis J1. ‥

The upper end of each second planetary shaft portion 63 is fixed to the second planetary carrier 62. As a result, each second planetary shaft portion 63 is non-rotatably fixed to the second planetary carrier 62. The plurality of second planetary shaft portions 63 are positioned radially outward of the sun gear 45 at substantially equal angular intervals in the circumferential direction. In the example shown in FIG. 1, the three second planetary shaft portions 63 are arranged at intervals of 120° in the circumferential direction. ‥

The second planetary shaft portion 63 may also be indirectly fixed to the second planetary carrier 62 via another member, or may be a member that is integrally connected to the second planetary carrier 62 (integrally molded). .. ‥

The plurality of second planetary gears 64 are arranged in the casing 2 in the circumferential direction on the outer side in the radial direction of the sun gear 45, and the second planetary gears 64 are respectively arranged in the casing 2 via the plurality of second planetary shaft portions 63. The carrier 62 is rotatably supported. In the example shown in FIG. 1, the three second planetary gears 64 are supported by the second planetary carrier 62 via the three second planetary shaft portions 63. The plurality of second planetary gears 64 are arranged at approximately the same positions in the axial direction as the inner peripheral teeth of the sun gear 45 and the second internal gear 7. ‥

The number and arrangement of the second planetary gears 64 and the second planetary shaft portions 63 may be changed as appropriate. ‥

Each second planetary gear 64 has a substantially cylindrical shape with the second planetary shaft portion 63 as a rotation axis. The outer peripheral surface of each second planetary gear 64 is provided with a plurality of teeth arranged in the circumferential direction. In the following description, the plurality of teeth on the outer peripheral surface of the second planetary gear 64 are referred to as “outer peripheral teeth”. ‥

The plurality of second planetary gears 64 are members having the same shape and the same size, and their outer peripheral teeth are engaged with the outer peripheral teeth of the sun gear 45 and the inner peripheral teeth of the second internal gear 7. Mate (mesh). ‥

Each second planetary gear 64 is rotatably supported by the second planetary shaft portion 63 about the second planetary shaft portion 63. That is, each of the plurality of second planetary gears 64 is rotatably supported by the second planetary carrier 62 about the second planetary axis J3 oriented in the direction along the central axis J1. ‥

On the other hand, the second planet carrier 62 is rotatably supported by the second internal gear 7. As described above, since the second internal gear 7 is fixed to the casing 2, the second planet carrier 62 is rotatably supported by the casing 2. ‥

<Output Shaft> The output shaft 9 is connected to the upper end portion of the second rotary shaft portion 61. The output shaft 9 rotates together with the second rotating shaft portion 61 outside the casing 2. ‥

The output shaft 9 may be indirectly connected to the second rotary shaft portion 61 via another member. As a connection method, various methods such as a connection using a key groove, a connection using a D-cut, and a connection using a gear component can be used. Further, the output shaft 9 may be a member that is integrally connected (integrally molded) with the second rotating shaft portion 61. ‥

<Operation of Reducer> In the small reducer 1, the input gear 33 rotates around the central axis J1 together with the input shaft 31 which is a high speed shaft. In other words, the input unit 3 rotates about the central axis J1. By the rotation of the input gear 33, each first planetary gear 44 engaged with the input gear 33 rotates about the first planetary shaft J2. ‥

As described above, since each first planetary gear 44 is also engaged with the first internal gear 5 fixed to the casing 2, the plurality of first planetary gears 44 rotate about the central axis J1. ‥

Here, the rotation of each first planetary gear 44 about the first planetary axis J2 and the rotation of the second planetary gear 64 about the second planetary axis J3 are referred to as "rotation". Further, the rotation of the plurality of first planetary gears 44 and the plurality of second planetary gears 64 about the central axis J1 is referred to as “revolution”. ‥

As described above, the first planetary carrier 42 is connected to the plurality of first planetary gears 44 via the plurality of first planetary shaft portions 43, and the first rotating shaft portion 41, which is the low speed shaft, is connected to the first planetary carrier 42. It is connected. Therefore, as the plurality of first planetary gears 44 revolve, the first planetary carrier 42, the first rotating shaft portion 41, and the sun gear 45 rotate about the central axis J1. That is, the first rotating body 4 rotates about the central axis J1. ‥

Due to the rotation of the first rotating body 4, the sun gear 45 rotates together with the first rotating shaft portion 41 about the central axis J1. By the rotation of the sun gear 45, each second planetary gear 64 engaged with the sun gear 45 rotates about the second planetary axis J3. As described above, since each second planetary gear 64 is also engaged with the second internal gear 7 fixed to the casing 2, the plurality of second planetary gears 64 rotate about the central axis J1. ‥

As described above, the second planetary carrier 62 is connected to the plurality of second planetary gears 64 via the plurality of second planetary shaft portions 63, and the second rotating shaft portion 61, which is the low speed shaft, is connected to the second planetary carrier 62. It is connected. Therefore, with the revolution of the plurality of second planetary gears 64, the second planetary carrier 62 and the second rotation shaft portion 61 rotate about the central axis J1. That is, the second rotating body 6 rotates about the central axis J1. ‥

In this way, the rotational force is transmitted between the input unit 3, the first rotating body 4, and the second rotating body 6. As a result of the transmission of the rotational force, the rotational force of the input shaft 8 that is directly connected to the motor 15 and rotates is taken out from the output shaft 9. ‥

<Material of Rotating Body Constituent Member> The small speed reducer 1 according to the present embodiment is formed to have a volume equal to or smaller than the external dimensions (width 5 mm, depth 5 mm, height 20 mm) described above, and The module of the first planetary gear 44 and the second planetary gear 64 of the second rotating body is, for example, 0.2 to 0.05 mm. Thereby, a microminiature molded part can be obtained. Further, by using such a component, it becomes possible to manufacture a precise speed reducer having the above-mentioned outer dimensions and suitable for mounting on other small-sized equipment. ‥

The input gear 33, the first planetary carrier 42, and the first planetary gear 44 are formed of a molded body of a resin composition containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined functional expression component. There is. The total content of the base resin and the inorganic whiskers in the resin composition is 99.5% by weight or more. ‥

Alternatively, the input gear 33, the first planetary carrier 42, and the first planetary gear 44 are molded products of a resin composition containing a thermoplastic resin as a base resin and containing an inorganic whisker and a lubricant as predetermined functional expression components. Is formed by. The total content of the base resin, the inorganic whiskers and the lubricant in the resin composition is 99.5% by weight or more, and the lubricant is contained by 1% by weight or more. ‥

The input gear 33 and the first planet carrier 42 or the input gear 33 and the first planet gear 44 are made of the same material, and the first planet gear 44 and the first planet carrier 42 are made of different materials. ‥

As a result of development studies by the present inventors, it is possible to obtain a result that wear of the gears can be reduced if the meshing gears are made of different materials. That is, since the first internal gear 5 is a strength component that constitutes the outer shape of the actuator, it is made of a material such as a metal sintered body by powder compaction with high tensile strength, a metal injection molding method (MIM), or a metal cut-out material. It is preferably formed. ‥

The meshing of the gears includes meshing of the input gear 33 and the first planetary gear 44, meshing of the first planetary gear 44 and the first internal gear 5, and meshing of the first planetary carrier 42 and the second rotating body 6. There are three types of engagement with.

In the case of a planetary speed reducer, the second rotating body 6 meshes with the sun gear 45 and the second planetary gear 64, and in the case of a spur gear, it meshes with the sun gear 45 and the spur gear. Here, since torque is also required for each gear, strength that can withstand the torque is required. In this case, the strength is not sufficient only with a base resin such as a polyamide resin, and it is preferable to add an inorganic whisker such as potassium titanate as a functional expression component. ‥

On the other hand, the inorganic whiskers have a higher hardness than the base resin, so that there is a problem that the base resin is worn. Therefore, by including an inorganic whisker and a lubricant in the base resin in one of the meshing gears, the coefficient of friction of the gear is reduced, and the excellent effect of reducing the amount of wear of the gear can be obtained. ‥

Hereinafter, specific combinations of materials will be described with reference to examples. [Embodiment 1] In the small speed reducer of Embodiment 1, the input gear 33 and the first planetary carrier 42 are resin molded bodies containing a thermoplastic resin as a base resin and an inorganic whisker as a predetermined functional component. Has been formed. The first planetary gear 44 is formed of a resin molded body containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined functional expression component and a lubricant. The first internal gear 5 is formed of a metal sintered body by powder compacting or a metal injection molding (MIM) method.

More specifically, the input gear 33, the first rotating shaft portion 41, which is a component of the first rotating body 4, the first planetary carrier 42, and the sun gear 45 are, for example, a thermoplastic resin such as a polyamide resin. Is used as a base resin, and a molded product of a resin composition containing inorganic whiskers in the base resin. The plurality of first planetary shaft portions 43 and the plurality of first planetary gears 44 are made of, for example, a thermoplastic resin such as polyamide resin as a base resin, and a resin composition containing an inorganic whisker and a lubricant in the base resin. Use as a molded body. ‥

The inorganic whiskers are, for example, potassium titanate fibers having an aspect ratio of 10 or more, and the first planetary carrier 42 and the like exhibit functionality such as fine moldability, durability, and releasability as a small component. It is the ingredient to do. That is, the potassium titanate fiber has a function of providing not only a high aspect ratio but also high strength and high rigidity in the mixed material with the resin. Further, the potassium titanate fiber has an extremely fine shape because its average fiber length is almost equal to the diameter of glass fiber, carbon fiber and the like. From this, in addition to the reinforcing property as the resin filler, excellent moldability and the like are exhibited in the ultra-small (micro-size) component used in the speed reducer according to the present embodiment. ‥

In the case of a molded product of a resin composition containing an inorganic whisker in the base resin like the input gear 33, the first planetary carrier 42, etc., the resin composition contains the base resin and the inorganic whisker in combination. The rate is 99.5% by weight or more. Specifically, the content of the base resin is, for example, 59.5 to 94.5% by weight, and the content of the inorganic whiskers is, for example, 5 to 40% by weight. The content of the inorganic whiskers in the resin composition is preferably 15-40% by weight, more preferably 20-30% by weight. The resin composition may contain components that are unavoidably mixed as other components (the balance) in addition to the above components. ‥

When the first planetary carrier 42 and the like are formed of a thermoplastic resin containing an inorganic whisker, they can be molded by using a method such as injection molding. A resin composition containing a polyamide resin containing an inorganic whisker is suitable for a small precision gear because it has excellent strength such as impact resistance and load resistance, and dimensional accuracy. ‥

As the thermoplastic resin described above, for example, a polycarbonate resin, an acrylic resin, a polyphenylene resin, a fluorine resin, or the like can be used instead of the polyamide resin. Further, in the inorganic whiskers, instead of potassium titanate fibers, for example, zinc oxide fibers, magnesium oxide fibers, aluminum oxide fibers, calcium sulfate fibers, silicon carbide fibers, silicon nitride fibers, mullite fibers, magnesium borate fibers, borated Titanium fiber or the like can be used. ‥

Therefore, the resin composition can be appropriately selected and combined from the above-mentioned thermoplastic resin and inorganic whiskers. Above all, a configuration in which a polyamide resin and potassium titanate fiber are combined is preferable. ‥

Further, in the case of a molded product of a resin composition in which an inorganic whisker and a lubricant are contained in a base resin like the above first planetary gear 44, the base resin, the inorganic whisker and the lubricant are combined in the resin composition. The ratio is 99.5% by weight or more, and the lubricant is contained by 1% by weight or more. Specifically, the base resin content is, for example, 59.5 to 94.5% by weight, the inorganic whisker content is, for example, 4 to 30% by weight, and the lubricant content is, for example, 1 to 10% by weight. .. The content of the lubricant in the resin composition is more preferably 1 to 5% by weight. The resin composition may contain components that are unavoidably mixed as other components (the balance) in addition to the above components. ‥

Examples of the lubricant include fluorine resin and olefin resins such as polyolefin. Examples of the fluorine resin include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylene-propene copolymer (FEP), polyvinylidene fluoride (PVDF), Examples thereof include polychlorotrifluoroethylene (PCTFE) and ethylene-chlorotrifluoroethylene copolymer (ECTFE). ‥

The configuration of the small speed reducer of the first embodiment is particularly effective when the load is large and wear resistance is required. Specifically, considering the meshing of a series of gears, first, by mixing the first planetary gear 44 with a lubricant, the meshing of all the gears can be made of different materials, and the wear of each gear can be prevented. The effect which can be prevented is acquired. In particular, when the first planetary gear 44 and the first internal gear 5 are meshed with each other, the lubricant is contained in the first planetary gear 44, so that the lubricity of the first planetary gear 44 with respect to the metal can be improved. .. As a result, the wear of the gear is further reduced and the durability of the gear unit can be improved. ‥

That is, since the first planetary gear 44 receives the input of the input gear 33, the first planetary gear 44 also has a large number of rotations, and the number of times the first planetary gear 44 comes into contact with the input gear 33 and the first planetary carrier 42 is large, so that more wear resistance is required. By including a lubricant in the first planetary gear 44 and using a material different from that of the input gear 33 and the first planetary carrier 42, it is possible to obtain an effect that the first planetary gear 44 is less likely to be scraped. ‥

On the other hand, the second rotary shaft portion 61, the second planetary carrier 62, and the second internal gear 7, which are the components of the second rotary body 6, are made of a sintered body by compaction molding or a metal injection molding method (MIM). Has been formed. The plurality of second planetary shaft portions 63 and the plurality of second planetary gears 64 are formed of a resin molded body containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined function expressing component and a lubricant. .. ‥

[Embodiment 2] In the small speed reducer of Embodiment 2, the input gear 33 and the first planetary gear 44 are resin molded bodies containing a thermoplastic resin as a base resin and containing inorganic whiskers as predetermined functional components. Has been formed. The first planetary carrier 42 is formed of a resin molded body containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined functional expression component and a lubricant. The first internal gear 5 is formed of a metal sintered body by powder compacting or a metal injection molding (MIM) method. ‥

On the other hand, the second rotary shaft portion 61, the second planetary carrier 62, and the second internal gear 7, which are the components of the second rotary body 6, are made of a sintered body by compaction molding or a metal injection molding method (MIM). Has been formed. The plurality of second planetary shaft portions 63 and the plurality of second planetary gears 64 are formed of a resin molded body containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined function expressing component.

The small speed reducer of the second embodiment exhibits basically the same operational effects as the small speed reducer of the first embodiment. That is, by forming the input gear 33 and the first planetary carrier 42 and the first planetary gear 44 with different materials, it is possible to obtain an effect that the first planetary gear 44 is less likely to be scraped. ‥

In the above-described first and second embodiments, the plurality of first planetary gears 44 and the plurality of second planetary gears 64 can be molded as a resin molded body with a common mold, and the cost can be reduced. Further, by using a common mold, the first planetary gear 44 and the second planetary gear 64 have the same tooth thickness, and the same tooth thickness results in the same surface roughness and tooth ratio. Therefore, the effect that it is easy to assemble is obtained. ‥

[Third Embodiment] In the small reduction gear of the third embodiment, the input gear 33 and the first planetary carrier 42 are resin moldings containing a thermoplastic resin as a base resin and an inorganic whisker as a predetermined functional expression component. Has been formed. The first planetary gear 44 is formed of a resin molded body containing a thermoplastic resin as a base resin and containing an inorganic whisker as a predetermined functional expression component and a lubricant. The first internal gear 5 is formed of a metal sintered body by powder compacting or a metal injection molding (MIM) method. ‥

On the other hand, the second rotary shaft portion 61, the second planetary carrier 62, the second internal gear 7, the plurality of second planetary shaft portions 63, and the plurality of second planetary gears 64, which are the components of the second rotating body 6, It is formed by a metal sintered body by powder compaction or a metal injection molding method (MIM). ‥

When the second rotating body 6 is composed of a spur gear that meshes with the sun gear 45, the spur gear is formed by a metal sintered body by powder compaction or a metal injection molding method (MIM). ‥

The small speed reducer of the third embodiment exhibits basically the same operational effects as the small speed reducers of the first and second embodiments. That is, by forming the input gear 33 and the first planetary carrier 42 and the first planetary gear 44 with different materials, it is possible to obtain an effect that the first planetary gear 44 is less likely to be scraped. ‥

In the speed reducers of Examples 1 to 3 described above, the gears constituting the gear unit are microminiature molded bodies, and in order to obtain good rotation between the gears, the tooth thickness portion of one gear is There must be an accurate mesh between the teeth of the. In this case, if the surface roughness of the teeth is rough, it is difficult for the teeth to mesh, and if the surface roughness is small, it is difficult for the teeth to mesh. Therefore, the ratio between the surface roughness and the tooth thickness of the internal gear is examined below. ‥

For example, the reference circle pitch diameter of the planetary gear: 1.5 mm, the number of teeth of the planetary gear: 14 pieces, the module of the planetary gear: the reference circle pitch diameter/the number of teeth = 0.107, the tooth thickness of the planetary gear: π/2 × Module ≈ 0.168 mm ・Internal gear surface roughness: 1.0 × 10 ^-3 mm or more and 8.0 × 10 ^-3 or less.

Here, since the tooth thickness of the planetary gear and the tooth thickness of the internal gear that meshes with the planetary gear are the same, the tooth thickness of the internal gear is approximately 0.168 mm as described above. Therefore, it is considered that a reasonable range is 0.12 mm or more and 0.2 mm or less with a margin for tooth thickness. ‥

From the above numerical values, Table 1 shows the ratio of the surface roughness Ra to the tooth thickness T that the internal gear can take (surface roughness/tooth thickness). Therefore, from Table 1, the range of the ratio of the surface roughness that can be realistically obtained when molding by the metal injection molding method (MIM) is 5.0×10 ⁻³ ≦(Ra/T)≦66.7× It becomes 10 ^-3 .

By defining the relationship between the tooth thickness T of the internal gear and the arithmetic mean roughness Ra as described above, the meshing with the gear that meshes with the internal gear, for example, the planetary gear that is a molded body of the resin composition is improved. As a result, the planetary gears that form the rotating assembly rotate smoothly. ‥

As described above, the small reduction gear 1 according to the present embodiment is the small reduction gear 1 that reduces the power from the input shaft 31 and transmits it to the output shaft 9, and includes the casing 2 and the first casing 2. An annular first internal gear 5 located on the inner peripheral surface, an input gear 33 connected to the input shaft 31, a first rotating shaft portion 41 arranged coaxially with the input shaft 33 in the casing 2, A first planetary carrier 42 that has a sun gear 45 that rotates together with the rotating shaft 41 and is rotatable around the first rotating shaft 41, and is rotatably supported by the first planetary carrier 42, and has an input gear 33 and a first planetary carrier 42. A plurality of first planetary gears 44 meshing with the first internal gear 42 and a second rotating body 6 rotatable by a sun gear 45 are provided. ‥

In the above-described structure of the small reduction gear 1, the input gear 33, the first planet carrier 42, and the first planet gear 44 are made of a thermoplastic resin as a base resin and contain an inorganic whisker as a predetermined functional component. Formed from a molded product of the resin composition, the total content of the base resin and the inorganic whiskers in the resin composition is 99.5% by weight or more, or the thermoplastic resin is used as the base resin, and a predetermined functionality is exhibited. Formed by a molded body of a resin composition containing an inorganic whisker as a component and a lubricant, wherein the total content of the base resin, the inorganic whisker and the lubricant in the resin composition is 99.5% by weight or more, Further, the lubricant is contained in an amount of 1% by weight or more, and the input gear 33 and the first planetary carrier 42, or the input gear 33 and the first planetary gear 44 are formed of the same material, and the first planetary gear 44 and the first planetary carrier 42 are formed. Are made of different materials.

Therefore, according to the small speed reducer according to the present embodiment, by mixing the lubricant in one of the gears that mesh with each other and configuring the gears that mesh with each other with different materials, each gear is less likely to be scraped and wear resistance is improved. To do. That is, since one of the gears is made of a soft material, it is possible to obtain an excellent effect that it is less likely to be scraped than the hard objects colliding with each other and scraping each other. ‥

In addition, a member close to the input shaft of the small reducer is made of a resin molded product that is ultra-compact, has good power transmission, and has high impact resistance and load resistance. By constructing all of them with metal, it is possible to realize a small speed reducer having durability and strength according to an applied load. Further, by adopting the resin, it becomes possible to mass-produce the members and improve the yield, and it is possible to reduce the cost of the speed reducer. Further, since the member near the input shaft that rotates at a high speed is made of resin, it is possible to perform a silent design that reduces noise during operation of the small reducer. ‥

In particular, by using a resin composition containing an inorganic whisker such as potassium titanate fiber in a thermoplastic resin such as a polyamide resin, fine moldability and durability as a small component are improved, and thin wall molding becomes possible. Become. In addition, the mold releasability from the mold is improved, and it is possible to manufacture a small precision gear with a high dimensional accuracy that suppresses burrs. At the same time, when the small parts are molded, the gate breakage of the resin is improved. ‥

Furthermore, unlike conventional speed reducers, the base resin does not contain carbon fiber, glass fiber, etc., so the fibers scraped away due to the mutual wear of meshing gears become dust or dust, which causes the rotation of gears. There is no problem of hindering. ‥

The present invention is not limited to the above-described embodiments and modifications, and can be implemented in various other forms without departing from the scope of the present invention. ‥

The small speed reducer according to the present invention can be used in various devices such as small cameras, robots, and other small and thin devices. The small speed reducer according to the present invention can also be used for other purposes.

1 reducer 2 casing 3 input part 4 1st rotating body 5 1st internal gear 6 2nd rotating body 7 2nd internal gear 8 input shaft 9 output shaft 15 motor 31 2nd input shaft 33 input gear 41 1st rotating shaft part 42 1st planetary carrier 43 1st planetary shaft part 44 1st planetary gear 45 1st planetary gear 45 2nd rotating part 62 2nd planetary carrier 63 2nd planetary shaft part 64 2nd planetary gear J1 central axis J2 1st planetary axis J3 3rd 2 planetary axes

Claims

A small reducer that reduces the power from the input shaft and transmits it to the output shaft, which is connected to the casing, an annular first internal gear located on the first inner peripheral surface of the casing, and the input shaft. Having an input gear, a first rotating shaft portion arranged coaxially with the input shaft in the casing, and a sun gear rotating together with the first rotating shaft portion, and rotating around the first rotating shaft portion. Possible first planetary carrier, a plurality of first planetary gears that are rotatably supported by the first planetary carrier and mesh with the input gear and the first internal gear, and a second rotation that can be rotated by the sun gear. A body, the input gear, the first planet carrier, and the first planet gear are made of a thermoplastic resin as a base resin, and a resin composition containing an inorganic whisker as a predetermined functional component. The content ratio of the base resin and the inorganic whiskers in the resin composition, which is formed by a molded body, is 99.5% by weight or more, or a thermoplastic resin is used as a base resin, and a predetermined functional expression component is obtained. And a content of the base resin, the inorganic whiskers and the lubricant in the resin composition is 99.5% by weight or more. And, the lubricant is contained by 1% by weight or more, the input gear and the first planet carrier, or the input gear and the first planet gear are formed of the same material, the first planet gear and the first planet Small reducer characterized in that the carrier is made of different materials.
The input gear and the first planet carrier are made of a thermoplastic resin as a base resin and formed of inorganic whiskers as a predetermined functional expression component, and the first planet gear is made of a thermoplastic resin as a base resin and have a predetermined function. The small reduction gear according to claim 1, wherein the first internal gear is formed of a metal sintered body, and the first internal gear is formed of an inorganic whisker as a property expressing component and a lubricant.
2. The relationship between the tooth thickness T of the first internal gear and the arithmetic mean roughness Ra satisfies 5.0×10 −3 ≦(Ra/T)≦66.7×10 −3. Small reducer described in.
The miniature speed reducer according to claim 1, wherein the second rotating body is a gear and is a resin composition made of the same material as that of the first planetary gear.
The second rotating body is composed of a second planetary gear, a second planetary carrier, and a second internal gear. The second planetary gear uses a thermoplastic resin as a base resin and as a predetermined functional expression component. Formed of a molded product of a resin composition containing the inorganic whiskers, and the total content of the base resin and the inorganic whiskers in the resin composition is 99.5% by weight or more. The miniature speed reducer according to claim 1, wherein the planet carrier and the second internal gear are formed of a metal sintered body.
The second rotating body is composed of a second planetary gear, a second planetary carrier, and a second internal gear. The second planetary gear is made of a thermoplastic resin as a base resin and serves as a predetermined functional expression component. Formed of a molded product of a resin composition containing an inorganic whisker, and the combined content of the base resin, the inorganic whisker and a lubricant in the resin composition is 99.5% by weight or more, and The small reduction gear according to claim 1, wherein the lubricant is contained in an amount of 1% by weight or more, and the second planet carrier and the second internal gear are formed of a sintered metal body.
The miniature speed reducer according to any one of claims 1 to 6, wherein the resin composition contains 15 to 40% by weight of the inorganic whiskers.
The miniature speed reducer according to claim 7, wherein the resin composition preferably contains 20 to 30% by weight of the inorganic whiskers.
The miniature speed reducer according to any one of claims 1 to 8, wherein the inorganic whiskers are potassium titanate fibers.
The miniature speed reducer according to claim 1, wherein the thermoplastic resin is a polyamide resin.
7. The small reduction gear according to claim 1, wherein the resin composition contains the lubricant in an amount of 1 to 10% by weight.
The miniature speed reducer according to claim 11, wherein the resin composition preferably contains the lubricant in an amount of 1 to 5% by weight.
The small speed reducer according to claim 11 or 12, wherein the lubricant is a fluorine resin or an olefin resin.
The miniature speed reducer according to claim 1, wherein the modules of the first planetary gear and the second planetary gear are 0.2 mm or less.
The small reducer according to claim 1, wherein the outer dimensions of the small reducer are formed to have a volume of 5 mm in width, 5 mm in depth, and 20 mm in height or less.
A first rotating body that transmits rotational force between the input gear, the first planetary carrier having the sun gear, the first planetary gear, and the first rotating shaft portion with the input shaft. The second planetary carrier, the second planetary gear, and the second rotating shaft portion form a second rotating body that transmits rotational force between the first rotating body and the first rotating body. The small reduction gear described in 1.