JP7705294B2 - Power transmission - Google Patents

Description

This disclosure relates to a power transmission device.

Patent Document 1 discloses a power transmission device that includes an external gear that rotates with the rotation of an input shaft, a pin that passes through the external gear, a roller that is arranged on the outer periphery of the pin, and a cover that is arranged axially to the side of the external gear. In the power transmission device of Patent Document 1, the external gear and the roller function as moving members that move with the rotation of the rotating shaft, and the cover functions as a restricting member that restricts the axial movement of the moving member.

JP 2006-183848 A

In the power transmission device of Patent Document 1, wear at the sliding points of the moving parts in the regulating member is an issue. To combat this wear, surface treatment to increase hardness is an effective way to deal with this. To achieve this, if the workpiece from which the regulating member is made is entirely hardened, thermal distortion will occur throughout the workpiece. Since thermal distortion can lead to additional processing after surface treatment, it is desirable to reduce the number of places where it occurs as much as possible. No technology that takes this into account has yet been proposed.

The present disclosure aims to provide a technology that can increase the hardness of the restricting member while reducing the number of locations where thermal distortion occurs.

The power transmission device disclosed herein comprises a moving member that moves due to the rotation of a rotating shaft, and a restricting member that restricts the axial movement of the moving member, the restricting member having a high hardness region in which the moving member slides, and a low hardness region having a surface hardness lower than that of the high hardness region.

According to the present disclosure, it is possible to increase the hardness of the restricting member while reducing the number of locations where thermal distortion occurs.

1 is a side cross-sectional view of a power transmission device according to a first embodiment. FIG. 2 is an enlarged view of a portion of FIG. 4 is a view of the restricting member of the first embodiment as viewed from the axial direction. FIG. 5A and 5B are diagrams illustrating the positional relationship between a moving member and a high hardness region of a regulating member in the first embodiment. 4 is a graph showing the relationship between the depth from the surface of the high hardness region and the Vickers hardness in the first embodiment. FIG. 11 is a side cross-sectional view showing a portion of a power transmission device according to a second embodiment. 13 is a view of a restricting member according to a second embodiment as viewed from an axial direction. FIG. 13 is a diagram showing the positional relationship between a moving member and a high hardness region of a regulating member in a second embodiment. FIG. FIG. 11 is a side cross-sectional view showing a portion of a power transmission device according to a third embodiment. FIG. 13 is a side cross-sectional view showing a power transmission device according to a fourth embodiment. FIG. 11 is an enlarged view of a portion of FIG. FIG. 12 is a view of the range Sc in FIG. 11 as viewed from the axial direction.

The following describes the embodiments. Identical components are given the same reference numerals, and duplicate descriptions are omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for ease of description. The drawings should be viewed according to the orientation of the reference numerals. In this specification, when distinguishing between multiple common components (e.g., moving members, high hardness regions, etc.), "A, B, C" is added to the end of the reference numeral, and this is omitted when referring to them collectively without distinction.

(First embodiment) Refer to Figure 1. The power transmission device 10 includes an input shaft 12, a gear mechanism 14 that transmits the rotation of the input shaft 12, an output member 16 that outputs the output rotation extracted from the gear mechanism 14 to a driven machine, and a casing 18 that houses the gear mechanism 14.

The gear mechanism 14 of this embodiment is an eccentric oscillating type reduction mechanism. This gear mechanism 14 includes external gears 22A, 22B and an internal gear 24A that mesh with each other and one of which becomes the oscillating gear 20. This gear mechanism 14 rotates either the external gears 22A, 22B or the internal gear 24A on its axis by oscillating the oscillating gear 20, and the rotation component can be extracted from the output member 16 as output rotation.

In addition, the power transmission device 10 of this embodiment includes a cover 26 arranged on one axial side (right side in the figure, hereinafter referred to as the input side) of the external gears 22A, 22B, a carrier 28 arranged on the other axial side (left side in the figure, hereinafter referred to as the non-input side) of the external gears 22A, 22B, a plurality of pins 30 integrated with the carrier 28, and a plurality of rollers 32 arranged on the outer periphery of each of the plurality of pins 30. In this embodiment, the external gears 22A, 22B are oscillating gears 20, and the external gears 22A, 22B rotate on their axes due to the oscillation of the oscillating gear 20, and the carrier 28 is the output member 16.

The input shaft 12 can be rotated by rotational power transmitted from a drive source (not shown). The drive source can be, for example, a motor, a gear motor, an engine, etc.

The input shaft 12 is a crankshaft having multiple eccentric bodies 34. The eccentric body 34 has an axis CL2 that is eccentric with respect to the rotation center line CL1 of the input shaft 12, and can oscillate the oscillating gear 20 (external gears 22A, 22B) by rotating around the rotation center line CL1. The multiple eccentric bodies 34 have different eccentric phases from each other. The eccentric phases of the multiple eccentric bodies 34 are shifted by (360°/M) when the number of eccentric bodies 34 is M (two in this embodiment). The number of eccentric bodies 34 is not particularly limited, and may be either one or three or more.

The oscillating gears 20 are provided individually corresponding to each of the multiple eccentric bodies 34, and are rotatably supported by the corresponding eccentric bodies 34 via eccentric body bearings 36. The external gears 22A and 22B that make up the oscillating gears 20 include a first external gear 22A provided on the input side and a second external gear 22B provided on the opposite input side.

In this embodiment, the internal gear 24A is integrated with the casing 18. The main bearing 38 is disposed between the casing 18 and the carrier 28.

The cover 26 covers the external gears 22A and 22B from the sides in the axial direction X. The cover 26 is connected to the casing 18 using a screw member and is integrated with the casing 18. The cover 26 and the carrier 28 are not connected via a pin 30 and can rotate relative to each other.

The multiple pins 30 protrude from the carrier 28 in the axial direction X and are integrated with the carrier 28. In this embodiment, the pins 30 are configured as part of the same member as the carrier 28, but may be configured separately from the carrier 28. The multiple pins 30 are cantilevered by the carrier 28. The multiple pins 30 are provided at intervals around the axis CL3 of the external gears 22A and 22B at positions radially offset from the axis CL3. The multiple pins 30 pass through insertion holes 40 formed in the external gears 22A and 22B in the axial direction X.

The multiple pins 30 can be synchronized with the rotational components of the external gears 22A and 22B when the external gears 22A and 22B oscillate. Here, "synchronization with the rotational components" refers to maintaining the rotational components of the external gears 22A and 22B and the revolutional components of the pins 30 at the same magnitude within a range including zero. When the carrier 28 is the output member 16 as in this embodiment, the multiple pins 30 synchronize with the rotational components of the external gears 22A and 22B by revolving with a revolutional component of the same magnitude as the rotational components (positive value) of the external gears 22A and 22B. In contrast, when the casing 18 is the output member 16, the multiple pins 30 synchronize with the rotational components of the external gears 22A and 22B by maintaining their own revolutional components at zero, just like the rotational components (zero value) of the external gears 22A and 22B.

The rollers 32 are cylindrical members rotatably supported by the pins 30. The rollers 32 are capable of rolling contact with both the insertion holes 40 of the external gears 22A and 22B and the pins 30, thereby reducing the frictional resistance between them. The rollers 32, like the pins 30, pass through the insertion holes 40 of the external gears 22A and 22B. In this embodiment, the rollers 32, like the pins 30, can be synchronized with the rotational components of the external gears 22A and 22B.

The operation of the power transmission device 10 described above will now be explained. When the input shaft 12 is rotated by the drive source, the gear mechanism 14 operates. When the gear mechanism 14 operates, the output rotation, which is speed-shifted (in this case, reduced) relative to the rotation of the input shaft 12, is taken out from the gear mechanism 14 through the output member 16 and output to the driven machine.

In this embodiment, the oscillating gear 20 is oscillated by the eccentric body 34 of the crankshaft that constitutes the input shaft 12. When the oscillating gear 20 oscillates, the meshing positions of the external gears 22A, 22B and the internal gear 24A change in the circumferential direction. As a result, either the external gears 22A, 22B or the internal gear 24A rotates, and the rotation component is taken out from the output member 16 as output rotation.

Refer to FIG. 2. Here, the power transmission device 10 of this embodiment includes a rotating shaft 50 that rotates when the power transmission device 10 is in operation, motion members 52A and 52B that move due to the rotation of the rotating shaft 50, a side member 54 that is disposed to the side of the motion members 52A and 52B in the axial direction X, and a restricting member 56 that restricts the movement of the motion members 52A and 52B in the axial direction X.

The rotating shaft 50 is provided on the power transmission path that runs from the input shaft 12 to the output member 16. In this embodiment, the rotating shaft 50 is the input shaft 12. Alternatively, the rotating shaft 50 may be an intermediate shaft that is provided on the output side of the input shaft 12 in the power transmission path. In this specification, the direction along the rotation center line of the rotating shaft 50 is referred to as the axial direction X.

The motion members 52A, 52B of this embodiment include a plurality of first motion members 52A which are rollers 32, and a second motion member 52B which is a first external gear 22A. The first motion member 52A (roller) revolves around a rotation center line (rotation center line CL1 of the rotation shaft 50 in this embodiment) located at a location different from its own axis CL4 as the rotation shaft 50 rotates. The second motion member 52B (first external gear 22A) rotates around its own axis CL3 as the rotation shaft 50 rotates. In this way, the motion members 52A, 52B of this embodiment move by rotating or revolving around the rotation of the rotation shaft 50.

The side member 54 in this embodiment is the cover 26 described above. A bearing 58 supported by the side member 54 is disposed between the side member 54 and the rotating shaft 50. The bearing 58 is a rolling bearing such as a ball bearing, and rotatably supports the rotating shaft 50.

The restricting member 56 is made of a steel material such as chrome molybdenum steel material (SCM material as defined by JIS), i.e., a metal material. The restricting member 56 is disposed to the side of the moving members 52A, 52B in the axial direction X. The restricting member 56 has a flat surface 56b provided on a side portion 56a that faces the moving members 52A, 52B in the axial direction X. The flat surface 56b is parallel to a plane perpendicular to the axial direction X of the rotating shaft 50. The restricting member 56 restricts the movement of the moving members 52A, 52B in the axial direction X toward the restricting member 56 side by the moving members 52A, 52B abutting against it. At this time, the moving members 52A, 52B abut against the flat surface 56b of the side portion 56a of the restricting member 56.

The restricting member 56 in this embodiment is provided separately from the side member 54 and is ring-shaped. The restricting member 56 is fitted into the inner periphery of the casing 18, which is a cylindrical member arranged on the outer periphery of the restricting member 56. The restricting member 56 is sandwiched between the side member 54 and the moving members 52A, 52B, so that the movement of the restricting member 56 in the axial direction X is restricted. The restricting member 56 is provided so as to be rotatable relative to the side member 54 and the moving members 52A, 52B in the circumferential direction. In other words, the restricting member 56 in this embodiment is not integral with the side member 54.

Refer to Figures 2 and 3. When the power transmission device 10 is in operation, the motion members 52A, 52B and the regulating member 56 move relative to each other, causing the motion members 52A, 52B to slide against the side portion 56a of the regulating member 56. Here, a first sliding range Ra in which the multiple first motion members 52A (rollers 32) slide against the regulating member 56 and a second sliding range Rb in which the second motion members 52B (first external gear 22A) slide against the regulating member 56 are shown.

The first moving member 52A (roller 32) slides in the first sliding range Ra by abutting its side surface in the axial direction X. The second moving member 52B (first external gear 22A) slides in the second sliding range Rb by abutting its side surface in the axial direction X. In this embodiment, the first sliding range Ra and the second sliding range Rb partially overlap. In this embodiment, the first sliding range Ra is a part of the flat surface 56b of the regulating member 56, and the second sliding range Rb is the entire area of the flat surface 56b. The first sliding range Ra and the second sliding range Rb are continuous in a ring shape. Although the multiple first moving members 52A are arranged at intervals, the first moving members 52A and the regulating member 56 rotate relatively when the multiple first moving members 52A rotate (revolve), so the first sliding range Ra is continuous in a ring shape.

Please refer to Figures 2 to 4. Figure 4 is a view of the side surfaces of the first moving member 52A (roller 32) and the second moving member 52B (first external gear 22A) in the axial direction X, and the high hardness regions 60A, 60B of the regulating member 56 projected in the axial direction X. The regulating member 56 has high hardness regions 60A, 60B and a low hardness region 62 having a lower surface hardness than the high hardness regions 60A, 60B. In Figures 2 and 3, the high hardness regions 60A, 60B are double hatched. In Figure 2, the low hardness region 62 is single hatched, and in Figure 3, the low hardness region 62 is not hatched.

The high hardness regions 60A, 60B and the low hardness region 62 are provided on the outer surface of the regulating member 56. The surface hardness here refers to the Vickers hardness measured by a method conforming to JIS Z2244. This surface hardness refers to the average value of the total hardness measured at a predetermined unit depth (e.g., 0.1 mm) over a predetermined range (e.g., 1.0 mm) in the depth direction (normal direction) from the outer surface of the referenced part. The hardness difference between the high hardness regions 60A, 60B and the low hardness region 62 is, for example, 50 [HV] or more in Vickers hardness. Note that the surface hardness of the moving members 52A, 52B is higher than that of the low hardness region 62 of the regulating member 56 in order to ensure strength.

The high hardness regions 60A, 60B are provided at the points where the moving members 52A, 52B abut in order to restrict the movement of the moving members 52A, 52B in the axial direction X. The high hardness regions 60A, 60B are provided at the points where the moving members 52A, 52B slide when the moving members 52A, 52B and the restricting member 56 move relative to each other during operation of the power transmission device 10. The high hardness regions 60A, 60B are provided to ensure wear resistance against the sliding of the moving members 52A, 52B.

The high hardness regions 60A, 60B include a first high hardness region 60A on which the first moving member 52A slides and a second high hardness region 60B on which the second moving member 52B slides. In this embodiment, the first high hardness region 60A also serves as the second high hardness region 60B, and these are integrally provided on the flat surface 56b of the regulating member 56. Each high hardness region 60A, 60B is continuous in an annular shape. This allows the first moving member 52A to always slide against the high hardness regions 60A, 60B of the regulating member 56 when the multiple first moving members 52A (rollers 32) and the regulating member 56 rotate relative to each other. The same is true when the second moving member 52B (first external gear 22A) and the regulating member 56 rotate relative to each other.

The low hardness region 62 is partially provided in the regulating member 56 at a location other than the high hardness regions 60A, 60B. In this embodiment, the low hardness region 62 is provided in the side portion 56a of the regulating member 56 at a location other than the high hardness regions 60A, 60B, and in the entire regulating member 56 at a location other than the side portion 56a. The low hardness region 62 provided in the side portion 56a of the regulating member 56 is continuous in an annular shape, similar to the high hardness regions 60A, 60B.

In this embodiment, the high hardness regions 60A, 60B and the low hardness region 62 are provided on a common flat surface 56b on the side portion 56a of the restricting member 56. These are provided in smooth, continuous areas on the flat surface 56b of the restricting member 56 without any steps.

The first high hardness region 60A is provided in a part of the first sliding range Ra in which the first moving member 52A (roller) slides. The first moving member 52A slides on both the first high hardness region 60A and the low hardness region 62 at the side portion 56a of the regulating member 56. The radial dimension of the annularly continuous first high hardness region 60A is smaller than the radial dimension of the annularly continuous first sliding range Ra. The radial dimension here refers to the dimension in the radial direction of a circle whose center is the axis CL5 of the regulating member 56.

The second high hardness region 60B is provided in a part of the second sliding range Rb in which the second moving member 52B (first external gear 22A) slides. The second moving member 52B slides in both the second high hardness region 60B and the low hardness region 62 at the side portion 56a of the regulating member 56. The radial dimension of the annularly continuous second high hardness region 60B is smaller than the radial dimension of the annularly continuous second sliding range Rb.

The restricting member 56 having the above-mentioned high hardness regions 60A, 60B and low hardness region 62 can be obtained by surface treatment of the workpiece that is the material of the restricting member 56. This workpiece is a processed product that has been machined into the product shape of the restricting member 56 by cutting, casting, or the like.

The high hardness regions 60A and 60B are formed by surface treatment regions provided by partially hardening the workpiece of the restricting member 56. Here, laser hardening is used as the partial hardening. The high hardness regions 60A and 60B of this embodiment are used in an unprocessed state after partial hardening. The low hardness region 62 is formed by a base material region having the hardness of the base material of the workpiece itself. The microstructure of the high hardness regions 60A and 60B thus formed has a hardened structure such as alpha martensite as the main phase. The microstructure of the low hardness region 62 has a standard structure such as a two-phase structure of ferrite and pearlite as the main phase.

Refer to Figure 5. In Figure 5, the Vickers hardness measured at multiple points from the surface of the high hardness regions 60A, 60B in the depth direction is plotted. The depth direction here refers to the direction perpendicular to the surface of the high hardness regions 60A, 60B. The numbers attached to the measurement points in the graph indicate the change in Vickers hardness from the adjacent measurement point on the surface side (hereinafter referred to as the hardness change). This hardness change indicates the change in Vickers hardness per 0.1 mm in the depth direction Pa.

The high hardness regions 60A, 60B formed by laser hardening are composed of a surface region 70 and a hardness transition region 72. The surface region 70 is continuous with the surface of the high hardness regions 60A, 60B, and is a region where the Vickers hardness does not decrease suddenly and where there is no large increase or decrease in Vickers hardness. Due to this relationship, the surface region 70 includes a portion where the hardness change is 0 or more, and is at least greater than -60. In addition, for example, the difference between the maximum and minimum values of Vickers hardness of the surface region 70 is 100 or less, and the hardness change is in the range of greater than -60 and less than +60.

The hardness transition region 72 is continuous from the surface region 70 to the base material region 74, and is a region where the hardness decreases rapidly in the depth direction. Due to this relationship, the hardness transition region 72 begins where the amount of hardness change in the depth direction switches from a value of 0 or more to a negative value, and includes a portion where the amount of hardness change is at least -60 or less. The length of the hardness transition region 72 in the depth direction is, for example, 0.3 mm to 0.8 mm.

The base material region 74 begins at the point where the amount of hardness change in the depth direction from the hardness transition region 72 switches from a negative value to a value greater than or equal to 0, and is a region in which the hardness does not increase or decrease significantly in the depth direction. Due to this relationship, in the base material region 74, for example, the difference between the maximum and minimum Vickers hardness values is 50 or less, and the amount of hardness change is between -50 and +50.

The manufacturing process for obtaining the above-mentioned regulating member 56 will now be described. First, a rough machining is performed to form a workpiece having the product shape of the regulating member 56. After the rough machining, a finish machining is performed to grind the outer surface of the workpiece of the regulating member 56 at a predetermined location that requires high shape accuracy. In this embodiment, the predetermined location is the location that will become the outer periphery of the regulating member 56. This is because high shape accuracy is required at this location to fit into the inner periphery of the casing 18. This finish machining is performed so that the surface roughness at the predetermined location is equal to or less than the target surface roughness. After this, a heat treatment is performed to partially harden the workpiece of the regulating member 56 at the locations that will become the high hardness regions 60A and 60B of the regulating member 56.

The effects of the power transmission device 10 described above will now be explained.

(A) The regulating member 56 has a low hardness region 62 in addition to the high hardness regions 60A, 60B where the moving members 52A, 52B slide. Such a regulating member 56 can be obtained by partially hardening the workpiece of the regulating member 56. Therefore, compared to when the workpiece of the regulating member 56 is entirely hardened, no thermal distortion occurs in the low hardness region 62. Furthermore, when increasing the hardness of the regulating member 56, the number of locations where thermal distortion occurs can be reduced.

If the entire workpiece is hardened, depending on the degree of thermal distortion, additional processing may be required to remove thermal distortion in areas where high hardness is not required but high shape precision is required (in this embodiment, the outer periphery of the regulating member 56). By making such areas requiring high shape precision into low hardness regions 62, additional processing for such hardened areas can be eliminated. Note that, in order to achieve the goal of reducing the number of areas where thermal distortion occurs, areas requiring high shape precision do not need to be present in the regulating member 56.

(B) The high hardness regions 60A, 60B and low hardness region 62 of the restricting member 56 are provided on the side 56a of the restricting member 56. Therefore, when partially hardening the workpiece of the restricting member 56, thermal distortion does not occur in the low hardness region 62 on the side 56a. In addition, compared to hardening the entire part of the restricting member 56 that becomes the side 56a of the workpiece, the number of places where thermal distortion occurs on the side 56a can be reduced.

(C) As another embodiment, a structure is envisaged in which a convex portion protruding toward the movement members 52A, 52B is provided on the side portion 56a of the regulating member 56, and the movement of the movement members 52A, 52B in the axial direction X is restricted by the convex portion. In this structure, the structure is complicated because the convex portion is provided on the side portion 56a of the regulating member 56. In this respect, according to the present embodiment, the high hardness regions 60A, 60B and the low hardness region 62 of the regulating member 56 are provided on a common flat surface 56b on the side portion 56a. Therefore, the movement of the movement members 52A, 52B in the axial direction X can be restricted by a simpler structure than the structure with the convex portion described above. As a result, the cost of parts required for the regulating member 56 can be reduced.

(D) The first moving member 52A slides in both the first high hardness region 60A and the low hardness region 62. Therefore, compared to when the first high hardness region 60A is provided in the entire first sliding range Ra in which the first moving member 52A slides in the restricting member 56, the range of the first high hardness region 60A in the first sliding range Ra of the restricting member 56 can be narrowed. Furthermore, compared to when the entire area of the first sliding range Ra of the workpiece of the restricting member 56 is hardened, the number of places where thermal distortion occurs in the first sliding range Ra can be reduced.

A similar effect can also be achieved by a structure in which the second moving member 52B slides in both the second high hardness region 60B and the low hardness region 62. In this case, the number of locations where thermal distortion occurs in the second sliding range Rb can be reduced compared to a case in which the second high hardness region 60B is provided in the restricting member 56 over the entire second sliding range Rb in which the second moving member 52B slides.

When the motion members 52A and 52B slide on the regulating member 56, a repeated load acts on the regulating member 56. This repeated load acts mainly on the high hardness regions 60A and 60B, and does not act strongly on the low hardness region 62. As a result, even if the motion members 52A and 52B slide on the low hardness region 62 of the regulating member 56, wear in the low hardness region 62 does not become a major problem. In addition, since the high hardness regions 60A and 60B themselves of the regulating member 56 have a higher surface hardness than the low hardness region 62, wear can be reduced even if such a repeated load acts on them. These factors combine to reduce wear in the entire sliding range Ra and Rb by simply providing the high hardness regions 60A and 60B in only a part of the sliding range Ra and Rb of the motion members 52A and 52B.

(E) The high hardness regions 60A, 60B include a first high hardness region 60A in which the first moving member 52A slides, and a second high hardness region 60B in which the second moving member 52B slides. Therefore, even when the first moving member 52A and the second moving member 52B each slide against the restricting member 56, as described above, the locations where thermal distortion occurs can be reduced.

(F) The high hardness regions 60A, 60B are formed by laser hardening, which has less thermal distortion compared to induction hardening and the like. Therefore, when restricting the movement of the motion members 52A, 52B by the high hardness regions 60A, 60B of the restricting member 56, the shape precision of the high hardness regions 60A, 60B can be easily ensured even without processing after laser hardening. Furthermore, post-processing after partial hardening can be eliminated to ensure shape precision for the areas that restrict the movement of the motion members 52A, 52B.

(Second embodiment) See Figs. 6, 7, and 8. In this embodiment, the sliding ranges Ra, Rb of each of the moving members 52A, 52B relative to the regulating member 56 are different from those in the first embodiment. In detail, in the first embodiment, an example was described in which the first sliding range Ra of the first moving member 52A (roller 32) and the second sliding range Rb of the second moving member 52B (first external gear 22A) relative to the regulating member 56 overlap. In contrast, in this embodiment, the first sliding range Ra of the first moving member 52A and the second sliding range Rb of the second moving member 52B are provided with a gap between them. In detail, the first sliding range Ra is provided on the inner periphery of the flat surface 56b of the side portion 56a of the regulating member 56. In addition, the second sliding range Rb is provided on the outer periphery of the flat surface 56b with a gap between them.

To achieve this, the sliding location of the second moving member 52B relative to the regulating member 56 is provided at a position radially shifted from the sliding location of the first moving member 52A relative to the regulating member 56. In detail, the second moving member 52B (first external gear 22A) has a thick-walled portion 80 having a large axial dimension and a thin-walled portion 82 having an axial dimension smaller than that of the thick-walled portion 80. The thick-walled portion 80 is provided at a position radially shifted toward the outer periphery side relative to the first moving member 52A (roller 32). The external teeth of the external gear 22A are provided on the thick-walled portion 80. The side surface of the thick-walled portion 80 in the axial direction X slides against the regulating member 56. The thin-walled portion 82 is provided on the inner periphery side of the thick-walled portion 80, and the side surface of the thin-walled portion in the axial direction X does not slide against the regulating member 56. This allows the sliding location of the second moving member 52B (thick portion 80) relative to the restricting member 56 to be shifted radially from the sliding location of the first moving member 52A.

In the first embodiment, an example was described in which the first high hardness region 60A in which the first moving member 52A slides also serves as the second high hardness region 60B in which the second moving member 52B slides. The first high hardness region 60A in this embodiment is provided separately from the second high hardness region 60B. In more detail, the first high hardness region 60A is provided in a part of the first sliding range Ra, and the second high hardness region 60B is provided in a part of the second sliding range Rb that is separate from the first sliding range Ra. As with each sliding range Ra, Rb, the first high hardness region 60A is provided on the inner periphery of the flat surface 56b of the side portion 56a, and the second high hardness region 60B is provided on the outer periphery of the flat surface 56b.

In addition, a low hardness region 62 is provided between the first high hardness region 60A and the second high hardness region 60B on the side portion 56a of the restricting member 56. This reduces the number of locations where thermal distortion occurs, compared to when the low hardness region 62 between the first high hardness region 60A and the second high hardness region 60B is made into the high hardness regions 60A and 60B. In addition, the low hardness region 62 is provided on the flat surface 56b of the side portion 56a of the restricting member 56, on the inner side of the first high hardness region 60A.

In addition, the power transmission device 10 of this embodiment also includes the components (not shown) described above in (A) to (F), and provides the effects corresponding to those descriptions.

(Third embodiment) See FIG. 9. This embodiment is different from the first embodiment in the regulating member 56. More specifically, in the first embodiment, an example was described in which the regulating member 56 is separate from the side member 54 and is not integrated with the side member 54. The regulating member 56 in this embodiment is the side member 54 (cover 26) itself. The side member 54 that becomes the regulating member 56 has a flat surface 56b provided on the side portion 56a that faces the moving members 52A and 52B in the axial direction X, similar to the first embodiment. This side member 54 has a first high hardness region 60A and a second high hardness region 60B in which the moving members 52A and 52B slide, and a low hardness region 62, similar to the first embodiment. As in the first embodiment, the high hardness regions 60A and 60B are provided on the flat surface 56b of the restricting member 56, and the low hardness region 62 is partially provided in a portion of the side member 54 other than the high hardness regions 60A and 60B.

(G) As a result, in order to restrict the movement of the motion members 52A and 52B in the axial direction X, a dedicated restricting member that is not integrated with the side member 54 that supports the bearing 58 is not required. In addition, the number of parts can be reduced, thereby reducing the cost of parts.

In order to obtain the same effect, the restricting member 56 may be integral with the side member 54. In this case, "integral" means that the side member 54 and the restricting member 56 are fixed so as not to move in both the axial direction X and the circumferential direction. In addition, in order to obtain the same effect, the side member 54 may support an oil seal 110 instead of the bearing 58, as will be described in the fourth embodiment below.

(Fourth embodiment) See FIG. 10. The power transmission device 10 includes an input shaft 12, a gear mechanism 14, an output member 16, and a casing 18, as in the first embodiment. The gear mechanism 14 of this embodiment differs from the first embodiment in that it is a flexible mesh type reduction mechanism. This gear mechanism 14 includes an external gear 22C and internal gears 24B, 24C that mesh with each other and one of which becomes a flexible gear 90. This gear mechanism 14 rotates one of the external gear 22C and the internal gears 24B, 24C by flexibly deforming the flexible gear 90, and the rotation component can be taken out as output rotation from the output member 16. The gear mechanism 14 of this embodiment is a cylindrical flexible mesh type reduction mechanism using a first internal gear 24B and a second internal gear 24C.

The power transmission device 10 of this embodiment also includes an input side cover 92 arranged on the axial input side of the flex gear 90, a counter-input side cover 94 arranged on the axial non-input side of the flex gear 90, and a pressing member 95 arranged between the counter-input side cover 94 and the flex gear 90. In this embodiment, the external gear 22C is the flex gear 90, and the output member 16 is the counter-input side cover 94.

The input shaft 12 in this embodiment is an exciter shaft. The input shaft 12, which is an exciter shaft, includes an exciter 96 that flexes and deforms the flexure gear 90, and shaft portions 98 provided on both axial sides of the exciter 96. The outer peripheral shape of the exciter 96 is elliptical in a cross section perpendicular to the axial direction of the exciter shaft. In this specification, "ellipse" is not limited to a geometrically strict ellipse, but also includes an approximate ellipse.

The flex gear 90 is rotatably supported by the vibrator 96 via the vibrator bearing 100. The external gear 22C that constitutes the flex gear 90 is a flexible cylindrical member. The vibrator bearing 100 corresponds to each of the multiple internal gears 24B, 24C, and is individually disposed inside the corresponding internal gear 24B, 24C.

The first internal gear 24B has a number of internal teeth (e.g., 102) different from the number of external teeth (e.g., 100) of the external gear 22C, and the second internal gear 24C has a number of internal teeth equal to the number of external teeth of the external gear 22C. The first internal gear 24B is integrated with the casing 18 and the input side cover 92. The second internal gear 24C is connected to the non-input side cover 94 and integrated therewith.

The casing 18 includes a first casing member 102 that also serves as the first internal gear 24B, and a second casing member 104 that is arranged on the outer periphery of the second internal gear 24C. The first casing member 102 and the second casing member 104 are integrated by being connected to each other. A main bearing 38 is arranged between the second casing member 104 and the second internal gear 24C.

The input side cover 92 covers the external gear 22C from the axial input side. The non-input side cover 94 covers the external gear 22C from the axial non-input side.

The pressing member 95 is provided separately from the non-input side cover 94 and has a ring shape. The pressing member 95 abuts against the flexure gear 90 to restrict its movement in the axial direction X.

In the above power transmission device 10, when the vibrator 96 of the vibrator shaft (input shaft 12) rotates, the flex gear 90 is flexibly deformed to form an ellipse that matches the shape of the vibrator 96. When the flex gear 90 is flexibly deformed in this manner, the meshing positions of the external gear 22C and the internal gears 24B, 24C change in the direction of rotation of the vibrator 96. At this time, the meshing positions of the external gear 22C and the first internal gear 24B, which have different numbers of teeth, shift in the circumferential direction every time they rotate once. As a result, one of them (the external gear 22C in this embodiment) rotates. In this embodiment, the external gear 22C and the second internal gear 24C have the same number of teeth, so even if their meshing positions rotate once, they are synchronized without rotating relative to each other. Therefore, the rotation component of the external gear 22C is taken out from the non-input side cover 94, which serves as the output member 16, through the second internal gear 24C, which is synchronized with the external gear 22C.

Refer to FIG. 11. Here, the power transmission device 10 of this embodiment includes a rotating shaft 50, a moving member 52C, a side member 54, and a restricting member 56, similar to the first embodiment.

The rotating shaft 50 in this embodiment is the input shaft 12 (vibrator shaft). The moving member 52C in this embodiment is a flexible gear 90. The moving member 52C is flexibly deformed by the rotation of the rotating shaft 50 so as to change the meshing position of the external gear 22C and the internal gears 24B and 22C in the rotational direction.

The side member 54 in this embodiment is the input side cover 92. Unlike the first embodiment, an oil seal 110 supported by the side member 54 is disposed between the side member 54 and the rotating shaft 50. The oil seal 110 seals a sealed space 112 in which the gear mechanism 14 is disposed. A lubricant used to lubricate the gear mechanism 14 is enclosed in the sealed space 112.

See Figures 11 and 12. The regulating member 56 is formed of a side member 54, as in the third embodiment. This regulating member 56 has a flat surface 56b provided on a side portion 56a that faces the moving member 52C in the axial direction X, as in the first and third embodiments. The moving member 52C (flex gear 90) slides in the sliding range Rc by abutting its side surface in the axial direction X. The sliding range Rc is continuous in an annular shape.

As in the above-described embodiment, this regulating member 56 has a high hardness region 60C and a low hardness region 62 along which the moving member 52C slides. The high hardness region 60C is provided on the flat surface 56b of the regulating member 56, and the low hardness region 62 is provided at a location other than the high hardness region 60C of the side member 54. The high hardness region 60C and the low hardness region 62 are provided on a common flat surface 56b on the side portion 56a of the regulating member 56.

The power transmission device 10 of this embodiment also includes the components (not shown) described above in (A)-(D), (F), and (G), and provides the effects corresponding to those descriptions.

Other variations of each component will be described. Hereinafter, when referring to components (moving members, etc.) collectively with the suffixes "A, B, C," these will be omitted.

Specific examples of the gear mechanism 14 are not particularly limited. The gear mechanism 14 may be, for example, a planetary gear mechanism, an orthogonal shaft gear mechanism, a parallel shaft gear mechanism, or the like.

As a specific type of eccentric oscillating gear mechanism 14, a center crank type in which the crankshaft (input shaft 12) is positioned on the axis of the internal gear 24 has been described. This type is not particularly limited, and for example, a distribution type in which multiple crankshafts are positioned at positions radially offset from the axis of the internal gear 24 may be used. Furthermore, in the eccentric oscillating gear mechanism 14, when the external gear 22 is used as the oscillating gear 20, the casing 18 may be used as the output member 16. Furthermore, the internal gear 24 may be used as the oscillating gear 20 instead of the external gear 22.

A cylindrical type has been described as a specific type of flexible meshing gear mechanism 14. This type is not particularly limited, and may be, for example, a cup type or a top hat type. Furthermore, when the external gear 22C is the flexible gear 90 in the flexible meshing gear mechanism 14, the casing 18 may be the output member 16. Furthermore, the internal gear 24 may be the flexible gear 90 instead of the external gear 22.

The moving member 52 may be any member that moves due to the rotation of the rotating shaft 50, and specific examples thereof are not particularly limited. The moving member 52 may be, for example, a gear such as a spur gear or a bevel gear, regardless of the type of the gear mechanism 14. In addition, the moving member 52 may be a rolling element or a retainer of a bearing such as the eccentric body bearing 36 or the vibrator bearing 100.

The combination of the moving member 52 and the regulating member 56 may be such that they slide against each other when the moving member 52 moves due to the rotation of the rotating shaft 50. To satisfy this condition, the moving mode of the moving member 52 is not particularly limited. For example, when the moving member 52 is an oscillating gear 20, the moving mode of the moving member 52 may be an oscillation without rotation. In this case, for example, in the example of FIG. 2, when the oscillating gear 20 that becomes the moving member 52 oscillates without rotation due to the rotation of the rotating shaft 50, the regulating member 56 and the oscillating gear 20 slide against each other without relative rotation. The oscillating gear 20 that moves by oscillating without rotation in this way may be the moving member 52. It can be said that the relative rotation between the moving member 52 and the regulating member 56 is not essential for the sliding against each other due to the movement of the moving member 52 (oscillating gear 20).

The oscillating gear 20 can be considered to oscillate by revolving around its axis, regardless of whether it rotates on its axis or not. When the oscillating gear 20 is considered to be a moving member 52, the moving member 52 can be said to rotate on its axis or revolve.

In addition, when the moving member 52 is a flexure gear 90, the moving mode of the moving member 52 may be a flexure deformation without rotation. In this case, for example, in the example of FIG. 10, when the rotation of the rotating shaft 50 causes the flexure gear 90, which is the moving member 52, to flexure deform without rotation, the pressing member 95 and the flexure gear 90 slide against each other without relative rotation. The flexure gear 90 that moves by flexure deformation without rotation in this way may be the moving member 52, and the pressing member 95 that slides due to the movement of the flexure gear 90 may be the regulating member 56. It can be said that the relative rotation between the moving member 52 and the regulating member 56 is not essential for the sliding of the moving member 52 and the regulating member 56 against each other due to the movement of the moving member 52 (flexure gear 90).

In the example of FIG. 10, when the flexure gear 90 flexes without rotating, the input cover 92 and the flexure gear 90 slide against each other with relative rotation, and the pressing member 95 and the flexure gear 90 slide against each other without relative rotation. The flexure gear 90 is the moving member 52, and each of the input cover 92 and the pressing member 95 that slide due to the movement of the flexure gear 90 may be an individual regulating member 56.

The restricting member 56 may be any member capable of restricting the movement of the moving member 52 in the axial direction X, and there are no particular limitations on the specific example. The restricting member 56 may be, for example, the cover 26, the carrier 28, the casing 18, the main bearing 38, etc.

The side member 54 is disposed to the side of the moving member 52 in the axial direction X, and may be any member that supports the bearing 58 or the oil seal 110, and there is no particular limitation on the specific example. The side member 54 may be, for example, the carrier 28, the casing 18, etc., other than the cover 26.

It is sufficient that at least a high hardness region 60 is provided on the side 56a of the regulating member 56, and it is not essential to provide a low hardness region 62. For example, a high hardness region 60 may be provided over the entire side 56a of the regulating member 56, and a low hardness region 62 may be provided on the outer surface of the regulating member 56 at a location other than the side 56a of the regulating member 56. Also, a high hardness region 60 may be provided over the entire sliding range of the moving member 52 on the side 56a of the regulating member 56, and a low hardness region 62 may be provided at a location other than the sliding range on the side 56a.

The high hardness region 60 and the low hardness region 62 do not have to be provided on the common flat surface 56b of the regulating member 56. This assumes, for example, a case in which a convex portion protruding toward the moving member 52 is provided on the side portion 56a of the regulating member 56, a high hardness region is provided on the convex portion, and a low hardness region is provided elsewhere.

In the above example, the regulating member 56 has multiple high hardness regions 60 against which each of the multiple moving members 52 slides. The number of high hardness regions 60 is not particularly limited. For example, if there are three or more moving members 52, there may be three or more high hardness regions 60 corresponding to the number of moving members 52. The number of high hardness regions 60 on the regulating member 56 may be one. This assumes that there is one moving member 52 sliding against the regulating member 56.

The partial hardening used to provide the high hardness region 60 in the restricting member 56 may be achieved by laser hardening or by induction hardening or other hardening performed outside the furnace. In addition, this partial hardening may be achieved by hardening performed in a heating furnace with areas other than the heat treatment area masked with anti-carburization or the like. When providing the high hardness region 60, additional processing may be performed on the high hardness region 60 after partial hardening to remove thermal distortion.

The above embodiments and variations are merely examples. The technical ideas abstracted from these should not be interpreted as being limited to the contents of the embodiments and variations. Many design changes are possible in the contents of the embodiments and variations, such as changing, adding, or deleting components. In the above-mentioned embodiments, the contents in which such design changes are possible are emphasized by adding the notation "embodiment". However, design changes are also permitted even in contents not so notated. Hatching on cross sections in the drawings does not limit the material of the hatched object. Furthermore, the structures referred to in the embodiments and variations naturally include those that can be considered to be the same when manufacturing errors are taken into account.

Any combination of the above components is also valid. For example, an embodiment may be combined with any of the description items of other embodiments, and a variant may be combined with any of the description items of an embodiment and another variant.

10...power transmission device, 22A, 22B, 22C...external gear, 32...roller, 50...rotating shaft, 52A...first moving member, 52B...second moving member, 52C...moving member, 54...side member, 56...regulating member, 56a...side portion, 56b...flat surface, 58...bearing, 60A...first high hardness region, 60B...second high hardness region, 60C...high hardness region, 62...low hardness region, 110...oil seal.

Claims (8)

In a power transmission device,
A motion member that moves due to rotation of a rotation shaft;
A restricting member that restricts the axial movement of the moving member,
The regulating member includes a high hardness region in which the moving member slides and a low hardness region having a surface hardness lower than that of the high hardness region ,
The motion members include a first motion member and a second motion member,
The power transmission device , wherein the high hardness region includes a first high hardness region in which the first moving member slides and a second high hardness region in which the second moving member slides . The power transmission device according to claim 1 , wherein the low hardness region is provided between the first high hardness region and the second high hardness region. the first moving member is a roller passing through the external gear,
3. The power transmission device according to claim 2 , wherein the second moving member is the external gear. In a power transmission device,
A motion member that moves due to rotation of a rotation shaft;
A restricting member that restricts the axial movement of the moving member,
The regulating member includes a high hardness region in which the moving member slides and a low hardness region having a surface hardness lower than that of the high hardness region,
a side member disposed on a side of the moving member in the axial direction and supporting either a bearing or an oil seal;
The regulating member is the side member itself or is integral with the side member. In a power transmission device,
A motion member that moves due to rotation of a rotation shaft;
A restricting member that restricts the axial movement of the moving member,
The regulating member includes a high hardness region in which the moving member slides and a low hardness region having a surface hardness lower than that of the high hardness region,
The power transmission device, wherein the high hardness region is provided by laser hardening. The regulating member has a side portion facing the moving member in the axial direction,
The power transmission device according to claim 1 , wherein the high hardness region and the low hardness region are provided in the side portion. the side portion has a flat surface;
The power transmission device according to claim 6 , wherein the high hardness region and the low hardness region are provided on the common flat surface. 8. The power transmission device according to claim 7 , wherein the moving member slides on both the high hardness area and the low hardness area.

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