JP7745468B2 - Flexure mesh gear device - Google Patents

Description

The present invention relates to a flexible mesh gear device.

BACKGROUND ART Conventionally, a flexible mesh gear device is known that includes an external gear that is flexibly deformed by a vibrator and an internal gear that meshes with the external gear (see, for example, Patent Document 1).
In this type of flexible mesh gear device, wear particles generated at the meshing portions of the gears and at the bearings, etc., get mixed into the lubricant. The wear particles mixed into the lubricant may find their way into the main bearings that support the output member. If the wear particles get into the main bearings, they accelerate wear on the main bearings and reduce their durability.

Japanese Patent Application Laid-Open No. 2021-97430

The present invention was made in consideration of the above circumstances, and aims to prevent a decrease in the durability of the main bearing.

The present invention provides a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear, an output member, a support member that supports the output member, and a main bearing that is disposed between the output member and the support member,
a communication passage that communicates between the meshing portion of the external gear and the internal gear and the main bearing;
an obstruction portion that obstructs passage of the lubricant through the communication passage;
a magnet that attracts foreign matter contained in the lubricant whose passage is obstructed by the obstruction portion ,
the communication passage has a radial gap radially communicating between the main bearing and an engagement portion of the external gear and the internal gear, the radial gap being located radially outward of the inhibition portion,
the inhibiting portion overlaps with the radial gap in the radial direction to inhibit passage of lubricant into the radial gap,
The magnet attracts foreign matter radially outward of the inhibiting portion that radially overlaps the radial gap .

This invention makes it possible to prevent a decrease in the durability of the main bearing.

FIG. 1 is a cross-sectional view showing a flexible mesh gear device according to an embodiment. FIG. 2 is an enlarged view of the vicinity of the contamination collection mechanism in FIG. 1. FIG. 10 is a diagram for explaining the operation of the contamination collection mechanism, showing the case where the flexible mesh gear device is installed horizontally. FIG. 10 is a diagram for explaining the operation of the contamination collection mechanism, showing the flexible mesh gear device installed vertically.

Embodiments of the present invention will be described in detail below with reference to the drawings.

[Configuration of flexure mesh gear device]
FIG. 1 is a cross-sectional view showing a flexible mesh gear device 1 according to this embodiment.
As shown in this figure, the flexible mesh gear device 1 is cylindrical and includes an exciter shaft 10, an external gear 11, a first internal gear 31G and a second internal gear 32G, an exciter bearing 12, a casing 33, a first cover 34, and a second cover 35.

The vibrator shaft 10 is a hollow cylindrical shaft that rotates around a rotation axis O1, and includes a vibrator 10A whose cross section perpendicular to the rotation axis O1 has a non-circular (e.g., elliptical) outer shape, and shaft portions 10B and 10C provided on both sides of the vibrator 10A in the axial direction. The elliptical shape is not limited to a geometrically strict ellipse, but also includes an approximate ellipse. The shaft portions 10B and 10C are shafts whose cross section perpendicular to the rotation axis O1 has a circular outer shape.
In the following description, the direction along the rotation axis O1 is referred to as the "axial direction," the direction perpendicular to the rotation axis O1 is referred to as the "radial direction," and the direction of rotation about the rotation axis O1 is referred to as the "circumferential direction." In addition, in the axial direction, the side that is connected to an external driven member (the left side in the drawing) is referred to as the "output side," and the side opposite the output side (the right side in the drawing) is referred to as the "anti-output side."

The external gear 11 is a flexible cylindrical member centered on the rotation axis O1, with teeth provided on its outer periphery. The material of the external gear 11 is not particularly limited, but in this embodiment it is a metal material such as steel.

The first internal gear 31G and the second internal gear 32G rotate around the rotation axis O1 around the vibrator shaft 10. Of these, the first internal gear 31G is configured by providing internal teeth at a corresponding location on the inner periphery of the first internal gear member 31. The second internal gear 32G is configured by providing internal teeth at a corresponding location on the inner periphery of the second internal gear member 32.
The first internal gear 31G and the second internal gear 32G are arranged side by side in the axial direction and mesh with the external gear 11. Specifically, the first internal gear 31G meshes with teeth of the external gear 11 on the opposite side from the axial center to the output side, and the second internal gear 32G meshes with teeth of the external gear 11 on the output side from the axial center.

The vibrator bearing 12 is, for example, a roller bearing, and is arranged between the vibrator 10A and the external gear 11. The vibrator bearing 12 has an outer ring 12a fitted onto the inner circumference of the external gear 11, multiple rolling elements (rollers) 12b, and a cage 12c that holds the multiple rolling elements 12b. The multiple rolling elements 12b roll on the outer surface of the vibrator 10A and the inner surface of the outer ring 12a as their rolling surfaces. The vibrator bearing 12 may have an inner ring separate from the vibrator 10A, or may not have an outer ring 12a.

Spacer rings 41, 42 are provided on both axial sides of the vibrator bearing 12 and the external gear 11, abutting against them and acting as restricting members that restrict their axial movement.

The casing 33 is connected to the first internal gear member 31 by bolts 43 and covers the outer diameter side of the second internal gear 32G. A main bearing 38 (e.g., a cross roller bearing) is disposed between the casing 33 and the second internal gear member 32, and the casing 33 rotatably supports the second internal gear member 32 via the main bearing 38. Furthermore, when the flexible mesh gear device 1 is connected to an external mating device, the casing 33 and the first internal gear member 31 are connected to the mating device by tightening them together. The second internal gear member 32 is an example of an output member according to the present invention, and the casing 33 is an example of a support member according to the present invention.

The first cover 34 is connected to the first internal gear member 31 by bolts 44 and covers the meshing point between the external gear 11 and the first internal gear 31G from the non-output side in the axial direction. A first bearing 36 (e.g., a ball bearing) is arranged between the first cover 34 and the shaft portion 10B of the vibrator shaft 10, and the first cover 34 rotatably supports the vibrator shaft 10 via the first bearing 36.

The second cover 35 is connected to the second internal gear member 32 by bolts 45 and covers the meshing point between the external gear 11 and the second internal gear 32G from the axial output side. A second bearing 37 (e.g., a ball bearing) is arranged between the second cover 35 and the shaft portion 10C of the vibrator shaft 10, and the second cover 35 rotatably supports the vibrator shaft 10 via this second bearing 37. When the flexible mesh gear device 1 is connected to an external mating device, the second cover 35 and the second internal gear member 32 are fastened together to connect to the driven member of the mating device, and output reduced rotation to the driven member.

Furthermore, the flexible mesh gear device 1 includes three O-rings 46 to 48 for sealing and three oil seals 51 to 53.
O-rings 46 to 48 are provided between the first internal gear member 31 and the first cover 34, between the first internal gear member 31 and the casing 33, and between the second internal gear member 32 and the second cover 35, respectively, to prevent the movement of lubricant between them.
The oil seal 51 is disposed at the end of the axial direction on the non-output side, between the shaft portion 10B of the vibrator shaft 10 and the first cover 34, and prevents the outflow of lubricant to the non-output side. The oil seal 52 is disposed at the end of the axial direction on the output side, between the shaft portion 10C of the vibrator shaft 10 and the second cover 35, and prevents the outflow of lubricant to the output side. The oil seal 53 is disposed between the casing 33 and the second internal gear member 32, and prevents the outflow of lubricant from this portion.
As a result, the lubricant is sealed in the seal space S inside the flexible mesh gear device 1, which is sealed by the three oil seals 51 to 53 and the three O-rings 46 to 48.

[Contamination collection mechanism]
The flexible meshing gear device 1 is equipped with a contaminant collection mechanism 60 that collects wear debris (contaminants; hereinafter simply referred to as "wear debris") generated at meshing portions, bearing portions, etc. Here, the "meshing portions" include the meshing portions between the external gear 11 and the internal gears (first internal gear 31G, second internal gear 32G), and the "bearing portions" include the vibrator bearing 12, the first bearing 36, and the second bearing 37 (as will be described later, the contaminant collection mechanism 60 mainly prevents foreign matter from entering the main bearing 38, and therefore does not include foreign matter generated at the main bearing 38). Furthermore, "wear debris" refers to debris generated by the friction of metal materials (external gear 11, rolling elements, etc.) at meshing portions and bearing portions, and includes metal debris (magnetic materials).

FIG. 2 is an enlarged view of the contaminant collection mechanism 60 and its surroundings in FIG.
As shown in this figure, the contaminant collection mechanism 60 captures and collects foreign matter, including wear powder, from the lubricant, mainly to prevent the foreign matter from entering the main bearing 38. The contaminant collection mechanism 60 is provided in a communication passage 61 that connects the meshing portion of the external gear 11 and the internal gear (first internal gear 31G, second internal gear 32G) with the main bearing 38. More specifically, the communication passage 61 includes a portion that extends radially outward from the meshing portion between the first internal gear member 31 and the second internal gear member 32, and a portion that extends axially between the first internal gear member 31 and the casing 33 from that portion to the main bearing 38.

Specifically, the contaminant collection mechanism 60 includes two magnets 62 (a first magnet 63 and a second magnet 64) that attract foreign matter contained in the lubricant while defining a portion of the communication passage 61. Each magnet 62 is formed in an axisymmetric shape with the rotation axis O1 as the axis of symmetry.
Of these, the first magnet 63 has an L-shaped cross section, with a disk portion 631 formed in the shape of an annular plate and a cylindrical portion 632 extending from the inner circumferential end of the disk portion 631 to the output side. The first magnet 63 is housed in a recess 31a formed in the output-side end face of the first internal gear member 31 facing the communicating passage 61. However, the output-side end of the cylindrical portion 632 of the first magnet 63 protrudes axially from the recess 31a into the communicating passage 61, forming an inhibiting portion 632a that inhibits the passage of lubricant through the communicating passage 61. In other words, the portion of the first magnet 63 other than the inhibiting portion 632a is housed in the recess 31a. It is preferable that the inhibiting portion 632a has a surface parallel to the axial direction.

The second magnet 64 faces the first magnet 63 in the axial direction, with a gap between them. Specifically, the second magnet 64 is tapered so that its diameter gradually decreases toward the output side, and is disposed on the non-output side end face of the second internal gear member 32 so as to face the disc portion 631 of the first magnet 63. Therefore, the non-output side surface of the second magnet 64 facing the first magnet 63 forms a tapered surface 64a that is inclined with respect to the axial direction. The communication passage 61 includes a portion formed by the gap between the first magnet 63 and the second magnet 64, and is narrowed toward the outer diameter side by the second magnet 64 (tapered surface 64a).

With the above-described configuration, the contaminant collection mechanism 60 effectively captures and collects foreign matter in the lubricant flowing through the communication passage 61, regardless of the installation state (orientation) of the flexible mesh gear device 1.

Specifically, when the flexible mesh gear device 1 is placed horizontally with its axial direction approximately parallel to the horizontal, as shown in Figure 3, the lubricant in the seal space S moves from the meshing portion between the external gear 11 and the internal gears 31G, 32G to the outer diameter side (downward) through the communication passage 61 due to gravity and centrifugal force from the external gear 11 and the second internal gear member 32. This lubricant contains foreign matter, including wear powder generated in the meshing portion and bearing portion.
At this time, the lubricant flows toward the outer diameter side through the output side of the inhibiting portion 632a, while foreign matter including wear debris is attracted to the inhibiting portion 632a, which is a magnet, by the inhibiting portion 632a that protrudes from the non-output side into the communicating passage 61. The lubricant that passes beside the inhibiting portion 632a flows diagonally toward the outer diameter side along the tapered surface 64a of the second magnet 64, while foreign matter including wear debris is further attracted by the second magnet 64 arranged on the outer diameter side. The lubricant then passes through the contaminant collection mechanism 60 and flows through the communicating passage 61 toward the main bearing 38.
In this way, the contaminant collection mechanism 60 can suitably capture and collect foreign matter in the lubricant flowing through the communication passage 61 when the flexible mesh gear device 1 is placed horizontally.

Furthermore, when the flexible mesh gear device 1 is placed vertically with its axial direction approximately perpendicular to the horizontal plane and the output side is on the upper side (vertically upper side), as shown in Figure 4(a), the lubricant in the seal space S moves from the meshing portion between the external gear 11 and the internal gears 31G, 32G to the outer diameter side within the communication passage 61 due to the centrifugal force received from the external gear 11 and the second internal gear member 32. This lubricant contains foreign matter, including wear powder generated in the meshing portion and bearing portion.
At this time, the lubricant flows toward the outer diameter side through the output side (upper side) of the inhibiting portion 632a, while foreign matter including wear debris is attracted to the inhibiting portion 632a, which is a magnet, by the inhibiting portion 632a that protrudes from the anti-output side (lower side) into the communicating passage 61. The lubricant that passes above the inhibiting portion 632a falls into the recess 31a of the first internal gear member 31, and foreign matter including wear debris is further attracted to the disk portion 631 of the first magnet 63, while the lubricant flows toward the outer diameter side over the disk portion 631. The lubricant then passes through the contamination collection mechanism 60 and flows through the communicating passage 61 toward the main bearing 38.
In this way, the contamination collection mechanism 60 can effectively capture and collect foreign matter in the lubricant flowing through the communicating passage 61 even when the flexible mesh gear device 1 is installed vertically and the output side is on the upper side (vertically upper side).

Furthermore, when the flexible mesh gear device 1 is placed vertically with its axial direction approximately perpendicular to the horizontal plane and the output side is on the lower side (vertically lower side), as shown in Figure 4(b), the lubricant in the seal space S moves from the meshing portion between the external gear 11 and the internal gears 31G, 32G to the outer diameter side within the communication passage 61 due to the centrifugal force received from the external gear 11 and the second internal gear member 32. This lubricant contains foreign matter, including wear powder generated in the meshing portion and bearing portion.
At this time, the lubricant flows through the output side (lower side) of the inhibitor 632a toward the outer diameter side, while foreign matter including wear debris is attracted to the inhibitor 632a, which is a magnet, by the inhibitor 632a that protrudes from the non-output side (upper side) into the communicating passage 61. The lubricant that passes below the inhibitor 632a flows diagonally toward the outer diameter side along the tapered surface 64a of the second magnet 64, while foreign matter including wear debris is further attracted by the second magnet 64 arranged on the outer diameter side. The lubricant then passes through the contaminant collection mechanism 60 and flows through the communicating passage 61 toward the main bearing 38.
In this way, the contamination collection mechanism 60 can effectively capture and collect foreign matter in the lubricant flowing through the communicating passage 61 even when the flexible mesh gear device 1 is installed vertically and the output side is on the lower side (vertically lower side).

[Operation of the reduction gear]
Next, the operation of the flexible mesh gear device 1 will be described.
When the vibrator shaft 10 is driven to rotate by a drive source such as a motor, the motion of the vibrator 10A is transmitted to the external gear 11. At this time, the external gear 11 is constrained to a shape that conforms to the outer circumferential surface of the vibrator 10A and is bent into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Furthermore, the external gear 11 is meshed with the fixed first internal gear 31G at its major axis portion. Therefore, the external gear 11 does not rotate at the same rotational speed as the vibrator 10A, and the vibrator 10A rotates relatively inside the external gear 11. Then, with this relative rotation, the external gear 11 is bent and deformed so that the major axis position and the minor axis position move circumferentially. The period of this deformation is proportional to the rotation period of the vibrator shaft 10.

When the external gear 11 flexes and deforms, its major axis position moves, causing the meshing position between the external gear 11 and the first internal gear 31G to change in the rotational direction. For example, if the external gear 11 has 100 teeth and the first internal gear 31G has 102 teeth, the meshing teeth between the external gear 11 and the first internal gear 31G will shift with each rotation of the meshing position, causing the external gear 11 to rotate (spin on its axis). With the above number of teeth, the rotational motion of the vibrator shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the external gear 11.

Meanwhile, because the external gear 11 also meshes with the second internal gear 32G, the meshing position between the external gear 11 and the second internal gear 32G also changes in the rotational direction as the vibrator shaft 10 rotates. Here, because the number of teeth on the second internal gear 32G is the same as the number of teeth on the external gear 11, the external gear 11 and the second internal gear 32G do not rotate relative to each other, and the rotational motion of the external gear 11 is transmitted to the second internal gear 32G at a reduction ratio of 1:1. As a result, the rotational motion of the vibrator shaft 10 is slowed down at a reduction ratio of 100:2 and transmitted to the second internal gear member 32 and second cover 35, and this rotational motion is output to the driven member.

At this time, as described above, within the seal space S, foreign matter in the lubricant flowing through the communication passage 61 is effectively captured and collected by the contaminant collection mechanism 60, regardless of the installation state (orientation) of the flexible mesh gear device 1. This prevents foreign matter from entering the main bearing 38, and ultimately prevents a decrease in the durability of the main bearing 38.

[Technical effect of this embodiment]
As described above, according to the flexible meshing gear device 1 of this embodiment, in the communication passage 61 that connects the meshing portions of the external gear 11 and the internal gears 31G, 32G with the main bearing 38, the passage of lubricant is obstructed by the obstructing portion 632a, and foreign matter contained in the lubricant whose passage is obstructed is attracted by the magnet 62.
This prevents foreign matter from entering the main bearing 38, and thus prevents a decrease in the durability of the main bearing 38. Furthermore, because the lubricant is purified, the durability of meshing parts and bearing parts other than the main bearing 38 is also improved.

Furthermore, according to the flexible mesh gear device 1 of this embodiment, the magnet 62 itself constitutes the inhibiting portion 632a.
This allows the configuration to be simpler than when the magnet and the inhibiting portion are separate, while still being able to effectively inhibit the flow of lubricant in the communication passage 61 and adsorb foreign matter.

Furthermore, according to the flexible mesh gear device 1 of this embodiment, the gap between the first magnet 63 and the second magnet 64 forms the communication passage 61 .
This allows foreign matter in the lubricant flowing through the communication passage 61 to be suitably attracted by at least one of the first magnet 63 and the second magnet 64 .

Furthermore, according to the flexible mesh gear device 1 of this embodiment, the surface of the second magnet 64 that faces the first magnet 63 is a tapered surface 64a that is inclined with respect to the axial direction.
This allows the lubricant to flow along the tapered surface 64a, while the tapered surface 64a can suitably adsorb foreign matter.

Furthermore, according to the flexible meshing gear device 1 of this embodiment, the magnet 62 (first magnet 63) has a stored portion that is stored in a recess 31a that is recessed from the communicating passage 61, and a portion that protrudes from the recess 31a into the communicating passage 61 and forms an inhibiting portion 632a.
As a result, the flow of the lubricant in the communication passage 61 is obstructed by the obstructing portion 632a, while foreign matter in the lubricant that has flowed into the recess 31a can be adsorbed by the receiving portion.

Furthermore, according to the flexible mesh gear device 1 of this embodiment, the inhibiting portion 632a has a surface that is parallel to the axial direction.
This makes it possible to effectively inhibit the flow of lubricant in the radial direction.

<Others>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.
For example, the specific configuration of the contaminant collection mechanism 60 is not limited to that of the above embodiment, as long as it has an obstruction portion that obstructs the passage of lubricant through the communication passage 61 and a magnet that attracts foreign matter contained in the lubricant whose passage has been obstructed. For example, it may be configured by combining two magnets that face each other and have an L-shaped cross section. Furthermore, the magnet and the obstruction portion may be separate bodies, or there may be only one magnet.

Furthermore, in the above embodiment, the function of the contaminant collection mechanism 60 when the flexible mesh gear device 1 is installed horizontally or vertically has been described as an example. However, even when the flexible mesh gear device 1 is installed with its axial direction oblique to the vertical direction, the contaminant collection mechanism 60 functions appropriately in a manner similar to that of the horizontal or vertical installation, which is close to the installation state.

In the above embodiment, a so-called cylindrical type has been exemplified as the flexible mesh gear device 1. However, the present invention is not limited to this and can also be applied to, for example, a so-called cup type or top hat type flexible mesh gear device.
In addition, the details shown in the above embodiment can be modified as appropriate without departing from the spirit of the invention.

1 Flexible mesh gear device 10A Vibrator 11 External gear 12 Vibrator bearing 31 First internal gear member 31a Recess 31G First internal gear 32 Second internal gear member (output member)
32G Second internal gear 33 Casing (support member)
38 Main bearing 60 Contamination collection mechanism 61 Communication passage 62 Magnet 63 First magnet 631 Disk portion 632 Cylindrical portion 632a Inhibition portion 64 Second magnet 64a Tapered surface O1 Rotation axis S Sealed space

Claims (7)

A flexible mesh gear device comprising: a vibration exciter; an external gear that is flexibly deformed by the vibration exciter; an internal gear; an output member; a support member that supports the output member; and a main bearing that is disposed between the output member and the support member,
a communication passage that communicates between the meshing portion of the external gear and the internal gear and the main bearing;
an obstruction portion that obstructs passage of the lubricant through the communication passage;
a magnet that attracts foreign matter contained in the lubricant whose passage is obstructed by the obstruction portion ,
the communication passage has a radial gap radially communicating between the main bearing and an engagement portion of the external gear and the internal gear, the radial gap being located radially outward of the inhibition portion,
the inhibiting portion overlaps with the radial gap in the radial direction to inhibit passage of lubricant into the radial gap,
the magnet attracts foreign matter radially outward of the inhibiting portion that radially overlaps with the radial gap;
Flexible mesh gearing. A part of the magnet is disposed in the communication passage and constitutes the inhibiting portion.
2. The flexible mesh gear device according to claim 1. The magnets include a first magnet and a second magnet facing the first magnet with a gap provided therebetween,
a gap between the first magnet and the second magnet constitutes the communication passage;
A surface of the second magnet facing the first magnet is inclined with respect to the radial direction.
2. The flexible mesh gear device according to claim 1 . a portion of either the first magnet or the second magnet protrudes into the communication passage to form the inhibiting portion;
4. The flexible mesh gear device according to claim 3. the communication passage includes an inner gap radially inward of the inhibiting portion,
The inner gap is axially longer than the radial gap.
2. The flexible mesh gear device according to claim 1 . The magnet has a received portion that is received in a recess that is recessed from the communication passage, and a portion that protrudes from the recess into the communication passage and constitutes the inhibiting portion.
The flexible mesh gear device according to any one of claims 1 to 5 . The inhibition portion has a surface parallel to the axial direction.
7. The flexible mesh gear device according to claim 6 .