Power transmission device

Abstract

To provide a technology capable of reducing heat strain generation locations while making hardness of a regulation member high.SOLUTION: A power transmission device of the present disclosure comprises motion members 52A and 52B that move by rotation of a rotating shaft 50, and a regulation member 56 for regulating movement of the motion members 52A and 52B in an axial direction X. The regulation member 56 has high-hardness regions 60A and 60B where the motion members 52A and 52B slide, and a low-hardness region 62 lower in surface hardness than the high-hardness regions 60A and 60B.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] Patent Document 1 discloses a power transmission device including an external gear that rotates by the rotation of an input shaft, a pin that penetrates the external gear, a roller disposed on the outer peripheral side of the pin, and a cover disposed axially laterally with respect to the external gear. In the power transmission device of Patent Document 1, the external gear and the roller function as moving members that move by the rotation of the rotating shaft, and the cover functions as a regulating member that regulates the axial movement of the moving members.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the power transmission device of Patent Document 1, wear at the sliding portion of the moving member in the regulating member becomes a problem. As a countermeasure against this wear, hardening by surface treatment is effective. In order to achieve this, if the workpiece that is the material of the regulating member is quenched as a whole, thermal distortion will occur in the whole workpiece. Since thermal distortion can cause post-processing after surface treatment, it is desirable to reduce the occurrence location as much as possible. A technique devised from such a viewpoint has not been proposed yet.

[0005] The present disclosure aims to provide a technique capable of reducing the occurrence location of thermal distortion while achieving hardening of the regulating member.

Means for Solving the Problems

[0006] The power transmission device of the present disclosure includes a moving member that moves by the rotation of a rotating shaft, and a restricting member that restricts the axial movement of the moving member. The restricting member includes a high-hardness region where the moving member slides, and a low-hardness region having a lower surface hardness than the high-hardness region.

Advantages of the Invention

[0007] According to the present disclosure, while achieving high hardness of the restricting member, it is possible to reduce the locations where thermal distortion occurs.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described. The same components are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the direction of the reference numerals. In this specification, when distinguishing a plurality of common components (for example, moving members, high-hardness regions, etc.), "A, B, C" are attached to the end of the reference numerals, and this is omitted when they are collectively referred to without distinction.

[0010] (First Embodiment) Referring to FIG. 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 taken out from the gear mechanism 14 to a driven machine, and a casing 18 that houses the gear mechanism 14.

[0011] The gear mechanism 14 of the present embodiment is an eccentric swing 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 a swing gear 20. This gear mechanism 14 can rotate any one of the external gears 22A, 22B and the internal gear 24A by swinging the swing gear 20, and take out the rotation component thereof as the output rotation from the output member 16.

[0012] In addition to this, the power transmission device 10 of the present embodiment includes a cover 26 disposed on one axial side (the right side in the figure; hereinafter referred to as the input side) with respect to the external gears 22A, 22B, and a carrier 28 disposed on the other axial side (the left side in the figure; hereinafter referred to as the anti-input side) with respect to the external gears 22A, 22B, a plurality of pins 30 integrated with the carrier 28, and a plurality of rollers 32 disposed on the outer peripheral side of each of the plurality of pins 30. In the present embodiment, the external gears 22A, 22B become the swing gear 20, the external gears 22A, 22B rotate by the swing of the swing gear 20, and the carrier 28 becomes the output member 16.

[0013] The input shaft 12 is rotatable by the rotational power transmitted from a drive source (not shown). The drive source is, for example, a motor, a gear motor, an engine, or the like.

[0014] The input shaft 12 is a crankshaft having a plurality of eccentric members 34. The eccentric member 34 has an axis CL2 that is eccentric with respect to the rotation center line CL1 of the input shaft 12, and by rotating around the rotation center line CL1, the oscillating gears 20 (external gear 22A, 22B) can be oscillated. The plurality of eccentric members 34 have different eccentric phases. When the number of the plurality of eccentric members 34 is M (2 in this embodiment), the eccentric phases of the plurality of eccentric members 34 are shifted by (360° / M). Note that the number of the eccentric members 34 is not particularly limited and may be either a single number or three or more numbers.

[0015] The oscillating gears 20 are individually provided corresponding to each of the plurality of eccentric members 34, and are rotatably supported by the corresponding eccentric members 34 via eccentric bearings 36. The external gears 22A, 22B serving as the oscillating gears 20 include a first external gear 22A provided on the input side and a second external gear 22B provided on the anti-input side.

[0016] The internal gear 24A of the present embodiment is integrated with the casing 18. A main bearing 38 is arranged between the casing 18 and the carrier 28.

[0017] The cover 26 covers the external gears 22A, 22B from the side 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 the pin 30 and are relatively rotatable with respect to each other.

[0018] The plurality of pins 30 protrude from the carrier 28 in the axial direction X and are integrated with the carrier 28. The pin 30 of the present embodiment is configured as a part of the same member as the carrier 28, but may be configured separately from the carrier 28. The plurality of pins 30 are cantilever-supported by the carrier 28. The plurality of pins 30 are provided at positions radially offset from the axis CL3 of the external gears 22A, 22B with an interval therearound. The plurality of pins 30 penetrate the insertion holes 40 formed in the external gears 22A, 22B in the axial direction X.

[0019] The plurality of pins 30 can be synchronized with the rotation components of the external gear wheels 22A and 22B when the external gear wheels 22A and 22B swing. Here, "synchronized with the rotation component" means maintaining the rotation components of the external gear wheels 22A and 22B and the revolution component of the pins 30 to be of the same magnitude within a range including zero. When the carrier 28 becomes the output member 16 as in the present embodiment, the plurality of pins 30 revolve with a revolution component of the same magnitude as the rotation component (positive value) of the external gear wheels 22A and 22B, thereby synchronizing with the rotation components of the external gear wheels 22A and 22B. On the other hand, when the casing 18 becomes the output member 16, the plurality of pins 30 synchronize with the rotation components of the external gear wheels 22A and 22B by maintaining their own revolution components in a zero state, similar to the rotation components (zero value) of the external gear wheels 22A and 22B.

[0020] The plurality of rollers 32 are cylindrical members rotatably supported by the pins 30. The rollers 32 have a role of reducing the frictional resistance between them by being able to rollingly contact both the insertion holes 40 of the external gear wheels 22A and 22B and the pins 30. The plurality of rollers 32 penetrate the insertion holes 40 of the external gear wheels 22A and 22B, similar to the pins 30. In the present embodiment, the plurality of rollers 32 can be synchronized with the rotation components of the external gear wheels 22A and 22B, similar to the pins 30.

[0021] The operation of the power transmission device 10 described above will be explained. When the input shaft 12 rotates by a drive source, the gear mechanism 14 operates. When the gear mechanism 14 operates, the output rotation decelerated (here, decelerated) with respect 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.

[0022] In the present embodiment, the swing gear 20 swings by the eccentric body 34 of the crankshaft constituting the input shaft 12. When the swing gear 20 swings, the meshing position between the external gear wheels 22A and 22B and the internal gear wheel 24A changes in the circumferential direction. As a result, either one of the external gear wheels 22A and 22B and the internal gear wheel 24A rotates, and the rotation component thereof is taken out from the output member 16 as the output rotation.

[0023] Refer to FIG. 2. Here, the power transmission device 10 of the present embodiment includes a rotating shaft 50 that rotates during the operation of the power transmission device 10, moving members 52A and 52B that move due to the rotation of the rotating shaft 50, a side member 54 disposed laterally on the side of the axial direction X with respect to the moving members 52A and 52B, and a restricting member 56 that restricts the movement of the moving members 52A and 52B in the axial direction X.

[0024] The rotating shaft 50 is provided on the power transmission path from the input shaft 12 to the output member 16. The rotating shaft 50 of the present embodiment is the input shaft 12. Alternatively, the rotating shaft 50 may be an intermediate shaft 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.

[0025] The moving members 52A and 52B of the present embodiment include a plurality of first moving members 52A that are rollers 32 and a second moving member 52B that is a first external gear 22A. The first moving member 52A (roller) revolves around a rotation center line (in the present embodiment, the rotation center line CL1 of the rotating shaft 50) at a location different from its own axis CL4 due to the rotation of the rotating shaft 50. The second moving member 52B (the first external gear 22A) rotates around its own axis CL3 due to the rotation of the rotating shaft 50. Thus, the moving members 52A and 52B of the present embodiment move by rotating or revolving due to the rotation of the rotating shaft 50.

[0026] The side member 54 of the present embodiment is the aforementioned cover 26. 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.

[0027] The restricting member 56 is made of a steel material such as chrome molybdenum steel (SCM material according to JIS), that is, it is made of metal. The restricting member 56 is arranged on the side in the axial direction X with respect to the moving members 52A and 52B. The restricting member 56 includes a flat surface 56b provided on a side portion 56a facing the moving members 52A and 52B in the axial direction X. The flat surface 56b is parallel to a plane orthogonal to the axial direction X of the rotating shaft 50. The restricting member 56 restricts the movement of the moving members 52A and 52B in the axial direction X toward the restricting member 56 when the moving members 52A and 52B come into contact. At this time, the moving members 52A and 52B come into contact with the flat surface 56b of the side portion 56a of the restricting member 56.

[0028] The restricting member 56 of the present embodiment is provided separately from the side member 54 and has a ring shape. This restricting member 56 is fitted into the inner peripheral portion of a casing 18 as a cylindrical member arranged on the outer peripheral side thereof. The restricting member 56 is restricted from moving in the axial direction X by being sandwiched between the side member 54 and the moving members 52A and 52B. The restricting member 56 is provided so as to be relatively rotatable in the circumferential direction with respect to the side member 54 and the moving members 52A and 52B. That is, the restricting member 56 of the present embodiment is not integral with the side member 54.

[0029] Refer to FIGS. 2 and 3. When the power transmission device 10 is operating, the moving members 52A and 52B and the restricting member 56 move relative to each other, so that the moving members 52A and 52B slide with respect to the side portion 56a of the restricting member 56. Here, a first sliding range Ra in which a plurality of first moving members 52A (rollers 32) slide with respect to the restricting member 56 and a second sliding range Rb in which a second moving member 52B (first external gear 22A) slides with respect to the restricting member 56 are shown.

[0030] The first moving member 52A (roller 32) slides within the first sliding range Ra by the contact of its side surface in the axial direction X. The second moving member 52B (first external gear 22A) slides within the second sliding range Rb by the contact of its side surface in the axial direction X. In the present embodiment, the first sliding range Ra and the second sliding range Rb partially overlap. Also, in the present embodiment, the first sliding range Ra forms part of the flat surface 56b of the regulating member 56, and the second sliding range Rb forms the entire flat surface 56b. Each of the first sliding range Ra and the second sliding range Rb is continuously annular. Although the plurality of first moving members 52A are arranged at intervals, since the first moving members 52A rotate (revolve) and the first moving members 52A and the regulating member 56 relatively rotate, the first sliding range Ra is continuously annular.

[0031] Refer to FIGS. 2 to 4. FIG. 4 is a view obtained by projecting 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 in the axial direction X. The regulating member 56 includes high-hardness regions 60A, 60B and a low-hardness region 62 having a surface hardness lower than that of the high-hardness regions 60A, 60B. In FIGS. 2 and 3, the high-hardness regions 60A, 60B are hatched doubly. In FIG. 2, the low-hardness region 62 is hatched singly, and in FIG. 3, the low-hardness region 62 is not hatched.

[0032] Each of the high-hardness regions 60A, 60B and the low-hardness region 62 is provided on the outer surface portion 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 every predetermined unit depth (for example, 0.1 mm) within a predetermined range (for example, 1.0 mm) in the depth direction (normal direction) from the outer surface of the mentioned location. The hardness difference between the high-hardness regions 60A, 60B and the low-hardness region 62 is, for example, 50 [HV] or more in terms of 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.

[0033] The high-hardness regions 60A and 60B are provided at the contact portions of the moving members 52A and 52B to restrict the movement of the moving members 52A and 52B in the axial direction X. The high-hardness regions 60A and 60B are provided at the locations where the moving members 52A and 52B slide when the moving members 52A, 52B and the restricting member 56 perform relative movement during the operation of the power transmission device 10. The high-hardness regions 60A and 60B are provided to ensure the wear resistance of the moving members 52A and 52B against sliding.

[0034] The high-hardness regions 60A and 60B include a first high-hardness region 60A where the first moving member 52A slides and a second high-hardness region 60B where the second moving member 52B slides. In the present embodiment, the first high-hardness region 60A also serves as the second high-hardness region 60B, and they are integrally provided on the flat surface 56b of the restricting member 56. Each of the high-hardness regions 60A and 60B is continuously annular. Thereby, when a plurality of the first moving members 52A (rollers 32) and the restricting member 56 rotate relative to each other, the first moving member 52A can always slide against the high-hardness regions 60A and 60B of the restricting member 56. The same applies when the second moving member 52B (the first external gear 22A) and the restricting member 56 rotate relative to each other.

[0035] The low-hardness region 62 is partially provided at locations other than the high-hardness regions 60A and 60B of the restricting member 56. In the present embodiment, the low-hardness region 62 is provided at locations other than the high-hardness regions 60A and 60B on the side portion 56a of the restricting member 56 and on the entire portion other than the side portion 56a of the restricting member 56. The low-hardness region 62 provided on the side portion 56a of the restricting member 56 is continuously annular, similar to the high-hardness regions 60A and 60B.

[0036] The high-hardness regions 60A and 60B and the low-hardness region 62 of the present embodiment are provided on the common flat surface 56b at the side portion 56a of the restricting member 56. These are provided at smooth locations that are continuously without steps on the flat surface 56b of the restricting member 56.

[0037] The first high-hardness region 60A is provided in a part of the first sliding range Ra where the first moving member 52A (roller) slides. The first moving member 52A will slide in both the first high-hardness region 60A and the low-hardness region 62 at the side portion 56a of the restricting 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 with the axis CL5 of the restricting member 56 as the center of the circle.

[0038] The second high-hardness region 60B is provided in a part of the second sliding range Rb where the second moving member 52B (the first external gear 22A) slides. The second moving member 52B will slide in both the second high-hardness region 60B and the low-hardness region 62 at the side portion 56a of the restricting 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.

[0039] The restricting member 56 having the above high-hardness regions 60A, 60B and the low-hardness region 62 can be obtained by surface-treating a workpiece that is the material of the restricting member 56. As this workpiece, a processed product processed into the product shape of the restricting member 56 by cutting, casting, etc. is used.

[0040] The high-hardness regions 60A, 60B are constituted by surface-treatment regions provided by performing partial quenching on the workpiece of the restricting member 56. Here, laser quenching is used as the partial quenching. The high-hardness regions 60A, 60B of the present embodiment are used in the state without being processed after partial quenching. Also, the low-hardness region 62 is constituted by a base material region having the hardness of the base material of the workpiece itself. The microstructure of the high-hardness regions 60A, 60B provided in this way has, for example, a quenched structure such as α martensite as the main phase. Also, the microstructure of the low-hardness region 62 has, for example, a standard structure such as a two-phase structure of ferrite and pearlite as the main phase.

[0041] Refer to Fig. 5. Fig. 5 plots the Vickers hardness measured at multiple locations in the depth direction from the surfaces of the high-hardness regions 60A and 60B. Here, the depth direction refers to the direction perpendicular to the surfaces of the high-hardness regions 60A and 60B. The numbers attached to the measurement points in the graph indicate the change amount of the Vickers hardness (hereinafter referred to as the hardness change amount) from the measurement point adjacent to the surface side. This hardness change amount indicates the change amount of the Vickers hardness per 0.1 mm in the depth direction Pa.

[0042] The high-hardness regions 60A and 60B provided by laser quenching are composed of a surface layer region 70 and a hardness transition region 72. The surface layer region 70 is continuous from the surfaces of the high-hardness regions 60A and 60B, and is a region where the Vickers hardness does not decrease rapidly and there is no large increase or decrease in the Vickers hardness. From this relationship, the surface layer region 70 includes locations where the hardness change amount is 0 or more, and is conditioned to be at least more than -60. Also, the surface layer region 70, for example, has a difference value between the maximum value and the minimum value of the Vickers hardness of 100 or less, and the hardness change amount is in the range of more than -60 and less than or equal to +60.

[0043] The hardness transition region 72 is continuous from the surface layer region 70 to the base material region 74, and is a region where the hardness decreases rapidly in the depth direction. From this relationship, the hardness transition region 72 starts from the location where the hardness change amount switches from a value of 0 or more to a negative value in the depth direction, and includes locations where the hardness change amount 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.

[0044] The base material region 74 starts from the location where the hardness change amount switches from a negative value to 0 or more in the depth direction from the hardness transition region 72, and is a region where the hardness does not increase or decrease significantly in the depth direction. From this relationship, the base material region 74, for example, has a difference value between the maximum value and the minimum value of the Vickers hardness of 50 or less, and the hardness change amount is -50 or more and 50 or less.

[0045] A manufacturing process for obtaining the above-described regulating member 56 will be described. First, rough machining is performed to form a workpiece having the product shape of the regulating member 56. After the rough machining, finish machining is performed to grind the outer surface portion of the workpiece of the regulating member 56, targeting a predetermined portion that requires high shape accuracy. In this embodiment, the predetermined portion here is the portion that becomes the outer peripheral portion of the regulating member 56. This is because high shape accuracy is required to fit it into the inner peripheral portion of the casing 18. This finish machining is performed so that the surface roughness at the predetermined portion becomes equal to or less than the target surface roughness. After that, heat treatment for partial quenching of the workpiece of the regulating member 56 is performed, targeting the portions that will become the high-hardness regions 60A and 60B of the regulating member 56.

[0046] The effects of the above-described power transmission device 10 will be described.

[0047] (A) The regulating member 56 includes a low-hardness region 62 in addition to the high-hardness regions 60A and 60B where the moving members 52A and 52B slide. Such a regulating member 56 can be obtained by partially quenching the workpiece of the regulating member 56. Therefore, compared with the case of quenching the entire workpiece of the regulating member 56, heat distortion does not occur in the low-hardness region 62. As a result, the locations where heat distortion occurs can be reduced in hardening the regulating member 56.

[0048] If the entire workpiece is quenched, although high hardness is not originally required, in a portion that requires high shape accuracy (in this embodiment, the outer peripheral portion of the regulating member 56), depending on the degree of heat distortion, additional machining for removing the heat distortion is required. By making the portion that requires such high shape accuracy the low-hardness region 62, additional machining for such hardened portions can be made unnecessary. In addition, in order to achieve the purpose of reducing the locations where heat distortion occurs, the portion that requires high shape accuracy does not necessarily have to exist in the regulating member 56.

[0049] (B) The high-hardness regions 60A and 60B and the low-hardness region 62 of the regulating member 56 are provided on the side portion 56a of the regulating member 56. Therefore, when partially quenching the workpiece of the regulating member 56, heat distortion does not occur in the low-hardness region 62 on the side portion 56a. As a result, compared with the case of quenching the entire portion that becomes the side portion 56a of the workpiece of the regulating member 56, the occurrence locations of heat distortion on the side portion 56a can be reduced.

[0050] (C) As another embodiment, a structure is assumed in which convex portions protruding toward the moving members 52A and 52B are provided on the side portion 56a of the regulating member 56, and the movement of the moving members 52A and 52B in the axial direction X is regulated by the convex portions. In the case of this structure, since convex portions are provided on the side portion 56a of the regulating member 56, the structure becomes complicated. In this regard, according to the present embodiment, the high-hardness regions 60A and 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 moving members 52A and 52B in the axial direction X can be regulated by a simple structure as compared with the structure provided with the aforementioned convex portions. As a result, it is possible to reduce the component cost required for the regulating member 56.

[0051] (D) The first moving member 52A slides on both the first high-hardness region 60A and the low-hardness region 62. Therefore, compared with the case where the first high-hardness region 60A is provided over the entire first sliding range Ra where the first moving member 52A slides in the regulating member 56, the range of the first high-hardness region 60A in the first sliding range Ra of the regulating member 56 can be narrowed. As a result, compared with the case of quenching the entire portion that becomes the first sliding range Ra of the workpiece of the regulating member 56, the occurrence locations of heat distortion in the first sliding range Ra can be reduced.

[0052] Also, the same effect can be obtained by a structure in which the second moving member 52B slides on both the second high-hardness region 60B and the low-hardness region 62. In this case, compared with the case where the second high-hardness region 60B is provided over the entire second sliding range Rb where the second moving member 52B slides in the regulating member 56, the occurrence locations of heat distortion in the second sliding range Rb can be reduced.

[0053] When the moving members 52A and 52B slide on the restricting member 56, a repeated load acts on the restricting member 56. This repeated load mainly acts on the high-hardness regions 60A and 60B and does not strongly act on the low-hardness region 62. As a result, even if the moving members 52A and 52B slide on the low-hardness region 62 of the restricting member 56, wear in the low-hardness region 62 does not become a major problem. Also, since the high-hardness regions 60A and 60B themselves of the restricting member 56 have a higher surface hardness than the low-hardness region 62, wear can be reduced even when such a repeated load acts. These factors combined enable the reduction of wear over the entire sliding ranges Ra and Rb by providing the high-hardness regions 60A and 60B only in a part of the sliding ranges Ra and Rb of the moving members 52A and 52B.

[0054] (E) The high-hardness regions 60A and 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. Therefore, even when each of the first moving member 52A and the second moving member 52B slides on the restricting member 56, the locations where thermal distortion occurs can be reduced as described above.

[0055] (F) The high-hardness regions 60A and 60B are provided by laser quenching, which causes less thermal distortion than high-frequency quenching or the like. Therefore, when restricting the movement of the moving members 52A and 52B by the high-hardness regions 60A and 60B of the restricting member 56, the shape accuracy of the high-hardness regions 60A and 60B can be easily ensured even without post-processing after laser quenching. Consequently, post-processing after partial quenching can be made unnecessary when ensuring shape accuracy regarding the locations where the movement of the moving members 52A and 52B is restricted.

[0056] (Second Embodiment) Refer to FIGS. 6, 7, and 8. In this embodiment, compared with the first embodiment, there are differences in the sliding ranges Ra and Rb of the respective moving members 52A and 52B with respect to the regulating member 56. Specifically, in the first embodiment, an example where the first sliding range Ra of the first moving member 52A (roller 32) with respect to the regulating member 56 and the second sliding range Rb of the second moving member 52B (first external gear 22A) overlap has been described. 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 therebetween. Specifically, the first sliding range Ra is provided on the inner peripheral side on the flat surface 56b of the side portion 56a of the regulating member 56. Also, the second sliding range Rb is provided on the outer peripheral side of the first sliding range Ra on the flat surface 56b, with a gap from the first sliding range Ra.

[0057] In order to achieve this, the sliding portion of the second moving member 52B with respect to the regulating member 56 is provided at a position radially displaced from the sliding portion of the first moving member 52A with respect to the regulating member 56. Specifically, the second moving member 52B (first external gear 22A) includes a thick portion 80 having a large axial dimension and a thin portion 82 having a smaller axial dimension than the thick portion 80. The thick portion 80 is provided at a position radially displaced to the outer peripheral side with respect to the first moving member 52A (roller 32). External teeth of the external gear 22A are provided on the thick portion 80. The side surface in the axial direction X of the thick portion 80 slides with respect to the regulating member 56. The thin portion 82 is provided on the inner peripheral side of the thick portion 80, and its side surface in the axial direction X does not slide with respect to the regulating member 56. Thereby, the sliding portion (thick portion 80) of the second moving member 52B with respect to the regulating member 56 and the sliding portion of the first moving member 52A can be displaced radially.

[0058] In the first embodiment, an example in which the first high-hardness region 60A on which the first moving member 52A slides also serves as the second high-hardness region 60B on which the second moving member 52B slides was described. The first high-hardness region 60A of the present embodiment is provided separately from the second high-hardness region 60B. Specifically, 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 different from the first sliding range Ra. Similar to each of the sliding ranges Ra and Rb, the first high-hardness region 60A is provided on the inner peripheral side on the flat surface 56b of the side portion 56a, and the second high-hardness region 60B is provided on the outer peripheral side on the flat surface 56b.

[0059] 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. Thereby, the location where thermal distortion occurs can be reduced as compared with the case where 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. Further, the low-hardness region 62 is provided on the inner peripheral side of the first high-hardness region 60A on the flat surface 56b of the side portion 56a of the restricting member 56.

[0060] In addition to this, the power transmission device 10 of the present embodiment also includes the components (not shown) described in the above (A) to (F), and the effects corresponding to those descriptions can be obtained.

[0061] (Third Embodiment) Refer to FIG. 9. In this embodiment, the regulating member 56 is different from that in the first embodiment. Specifically, in the first embodiment, an example where the regulating member 56 is separate from and not integrated with the side member 54 was described. The regulating member 56 in this embodiment is the side member 54 (cover 26) itself. The side member 54 serving as the regulating member 56 includes a flat surface 56b provided on a side portion 56a facing the moving members 52A and 52B in the axial direction X, similar to the first embodiment. This side member 54 includes a first high-hardness region 60A and a second high-hardness region 60B where the moving members 52A and 52B slide, and a low-hardness region 62, similar to the first embodiment. Each of the high-hardness regions 60A and 60B is provided on the flat surface 56b of the regulating member 56, similar to the first embodiment, and the low-hardness region 62 is partially provided at locations other than the high-hardness regions 60A and 60B of the side member 54.

[0062] (G) As a result, in restricting the movement of the moving members 52A and 52B in the axial direction X, a dedicated regulating member that is not integrated with the side member 54 supporting the bearing 58 becomes unnecessary. Consequently, the component cost can be reduced by reducing the number of components.

[0063] Note that, in order to obtain a similar effect, the regulating member 56 may be integrated with the side member 54. Here, "integrated" means that the side member 54 and the regulating member 56 are fixed immovably in both the axial direction X and the circumferential direction. Also, in order to obtain a similar effect, as described in the fourth embodiment to be described later, the side member 54 may support an oil seal 110 instead of the bearing 58.

[0064] (Fourth Embodiment) Referring to FIG. 10. The power transmission device 10 includes an input shaft 12, a gear mechanism 14, an output member 16, and a casing 18, similar to the first embodiment. The gear mechanism 14 of this embodiment is different in that it is a deflection meshing type reduction mechanism compared to the first embodiment. This gear mechanism 14 includes an external gear 22C and internal gears 24B and 24C that mesh with each other and one of which is a deflection gear 90. This gear mechanism 14 can rotate one of the external gear 22C and the internal gears 24B and 24C by deflecting the deflection gear 90, and extract the rotation component as output rotation from the output member 16. The gear mechanism 14 of this embodiment is a cylindrical deflection meshing type reduction mechanism using the first internal gear 24B and the second internal gear 24C.

[0065] In addition to this, the power transmission device 10 of this embodiment includes an input side cover 92 disposed on the input side in the axial direction with respect to the deflection gear 90, a counter-input side cover 94 disposed on the counter-input side in the axial direction with respect to the deflection gear 90, and a pressing member 95 disposed between the counter-input side cover 94 and the deflection gear 90. In this embodiment, the external gear 22C becomes the deflection gear 90, and the output member 16 becomes the counter-input side cover 94.

[0066] The input shaft 12 of this embodiment is an oscillation body shaft. The input shaft 12, which is an oscillation body shaft, includes an oscillation body 96 that deflects the deflection gear 90 and shaft portions 98 provided on both sides in the axial direction with respect to the oscillation body 96. The outer peripheral shape of the oscillation body 96 is elliptical in a cross section perpendicular to the axial direction of the oscillation body shaft. The "ellipse" in this specification is not limited to a geometrically exact ellipse and includes a substantially ellipse.

[0067] The deflection gear 90 is rotatably supported by the oscillation body 96 via an oscillation body bearing 100. The external gear 22C constituting the deflection gear 90 is a flexible cylindrical member. The oscillation body bearing 100 corresponds to each of the plurality of internal gears 24B and 24C and is individually disposed inside the corresponding internal gears 24B and 24C.

[0068] The first internal gear 24B has an internal tooth number (e.g., 102) different from the external tooth number (e.g., 100) of the external gear 22C, and the second internal gear 24C has the same number of internal teeth as the external tooth number 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 and integrated with the anti-input side cover 94.

[0069] The casing 18 includes a first casing member 102 that also serves as the first internal gear 24B, and a second casing member 104 disposed on the outer peripheral side 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 disposed between the second casing member 104 and the second internal gear 24C.

[0070] The input side cover 92 covers the external gear 22C from the axial input side. The anti-input side cover 94 covers the external gear 22C from the axial anti-input side.

[0071] The pressing member 95 is provided separately from the anti-input side cover 94 and is ring-shaped. The pressing member 95 restricts the movement of the flexure gear 90 in the axial direction X by contacting the flexure gear 90.

[0072] In the above power transmission device 10, when the oscillator 96 on the oscillator shaft (input shaft 12) rotates, the flexure gear 90 is flexurally deformed to form an elliptical shape according to the shape of the oscillator 96. When the flexure gear 90 is flexurally deformed in this way, the meshing positions of the external gear 22C and the internal gears 24B and 24C change in the rotation direction of the oscillator 96. At this time, every time the meshing position of the external gear 22C and the first internal gear 24B with different tooth numbers makes one revolution, the meshing teeth shift in the circumferential direction. As a result, one of them (the external gear 22C in this embodiment) rotates. In this embodiment, since the external gear 22C and the second internal gear 24C have the same number of teeth, they synchronize without relative rotation even when their meshing positions make one revolution. Therefore, the rotation component of the external gear 22C is taken out from the anti-input side cover 94 as the output member 16 through the second internal gear 24C that synchronizes with the external gear 22C.

[0073] Refer to FIG. 11. Here, the power transmission device 10 of the present embodiment includes a rotating shaft 50, a moving member 52C, a side member 54, and a regulating member 56, similar to the first embodiment.

[0074] The rotating shaft 50 of the present embodiment is the input shaft 12 (oscillator shaft). The moving member 52C of the present embodiment is a flexible gear 90. The moving member 52C is flexurally 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.

[0075] The side member 54 of the present embodiment is the input side cover 92. Different from 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 for lubricating the gear mechanism 14 is enclosed in the sealed space 112.

[0076] Refer to FIGS. 11 and 12. The regulating member 56 is constituted by the side member 54, similar to the third embodiment. This regulating member 56 includes a flat surface 56b provided on a side portion 56a facing the moving member 52C in the axial direction X, similar to the first and third embodiments. The moving member 52C (flexible gear 90) slides within a sliding range Rc by the contact of its side surface in the axial direction X. The sliding range Rc is continuously annular.

[0077] This regulating member 56 includes a high hardness region 60C and a low hardness region 62 on which the moving member 52C slides, similar to the foregoing embodiments. 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 at the side portion 56a of the regulating member 56.

[0078] The power transmission device 10 of the present embodiment also includes the components (not shown) described in the foregoing (A) to (D), (F), and (G), and the effects corresponding to those descriptions can be obtained.

[0079] Other deformation forms of each component will be described. Hereinafter, when collectively referring to components (such as moving members) with "A, B, C" appended to the end of the reference signs, this will be omitted.

[0080] The specific example of the gear mechanism 14 is not particularly limited. The gear mechanism 14 may be, for example, any of a planetary gear mechanism, an orthogonal axis gear mechanism, a parallel axis gear mechanism, etc.

[0081] As a specific type of the eccentric swing type gear mechanism 14, the center crank type in which the crank shaft (input shaft 12) is arranged 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 a plurality of crank shafts are arranged at positions offset radially from the axis of the internal gear 24 may also be used. Further, when the external gear 22 is used as the swing gear 20 in the eccentric swing type gear mechanism 14, the casing 18 may be used as the output member 16. Further, instead of the external gear 22, the internal gear 24 may be used as the swing gear 20.

[0082] As a specific type of the flexure engagement type gear mechanism 14, the cylindrical type has been described. This type is not particularly limited, and for example, a cup type or a silk hat type may also be used. Further, when the external gear 22C is used as the flexure gear 90 in the flexure engagement type gear mechanism 14, the casing 18 may be used as the output member 16. Further, instead of the external gear 22, the internal gear 24 may be used as the flexure gear 90.

[0083] The moving member 52 only needs to move by the rotation of the rotating shaft 50, and its specific example is 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 to this, the moving member 52 may be a rolling element or a retainer of a bearing such as an eccentric bearing 36 or an oscillation body bearing 100.

[0084] The combination of the moving member 52 and the restricting member 56 only needs to be such that they slide relative to each other when the moving member 52 moves due to the rotation of the rotation shaft 50. Under the condition of satisfying this, the motion mode of the moving member 52 is not particularly limited. For example, when the moving member 52 is the oscillating gear 20, the motion mode of the moving member 52 may be oscillation without rotation. In this case, for example, in the example of FIG. 2, when the oscillating gear 20 serving as the moving member 52 oscillates without rotation due to the rotation of the rotation shaft 50, the restricting member 56 and the oscillating gear 20 slide relative to each other without relative rotation. Thus, the oscillating gear 20 that moves by oscillating without rotation may be used as the moving member 52. It can also be said that relative rotation is not essential for the moving member 52 (oscillating gear 20) to move and for the moving member 52 and the restricting member 56 to slide relative to each other.

[0085] Note that the oscillating gear 20 can be regarded as oscillating by revolving the axis of the oscillating gear 20 regardless of whether it rotates or not. When the oscillating gear 20 is regarded as the moving member 52, the moving member 52 can be said to rotate or revolve.

[0086] In addition to this, when the moving member 52 is the flexible gear 90, the motion mode of the moving member 52 may be flexible deformation without rotation. In this case, for example, in the example of FIG. 10, when the flexible gear 90 serving as the moving member 52 undergoes flexible deformation without rotation due to the rotation of the rotation shaft 50, the pressing member 95 and the flexible gear 90 slide relative to each other without relative rotation. Thus, the flexible gear 90 that moves by undergoing flexible deformation without rotation may be used as the moving member 52, and the pressing member 95 that slides due to the movement of the flexible gear 90 may be used as the restricting member 56. It can also be said that relative rotation is not essential for the moving member 52 (flexible gear 90) to move and for the moving member 52 and the restricting member 56 to slide relative to each other.

[0087] In the example of FIG. 10, when the flexible gear 90 is flexurally deformed without rotating, the input-side cover 92 and the flexible gear 90 slide relative to each other with relative rotation, and the pressing member 95 and the flexible gear 90 slide relative to each other without relative rotation. The flexible gear 90 may be used as the moving member 52, and the input-side cover 92 and the pressing member 95 that slide due to the movement of the flexible gear 90 may be used as individual restricting members 56, respectively.

[0088] The restricting member 56 only needs to be able to restrict the movement of the moving member 52 in the axial direction X, and its specific example is not particularly limited. The restricting member 56 may be, for example, in addition to the cover 26, the carrier 28, the casing 18, the main bearing 38, etc.

[0089] The side member 54 is disposed on the side in the axial direction X of the moving member 52 and only needs to support the bearing 58 or the oil seal 110, and its specific example is not particularly limited. The side member 54 may be, for example, in addition to the cover 26, the carrier 28, the casing 18, etc.

[0090] It is sufficient that at least the high-hardness region 60 is provided on the side portion 56a of the restricting member 56, and it is not essential to provide the low-hardness region 62. For example, the high-hardness region 60 may be provided over the entire side portion 56a of the restricting member 56, and the low-hardness region 62 may be provided on the outer surface portion of the restricting member 56 at locations other than the side portion 56a. Also, the high-hardness region 60 may be provided over the entire sliding range of the moving member 52 in the side portion 56a of the restricting member 56, and the low-hardness region 62 may be provided at locations other than the sliding range in the side portion 56a.

[0091] The high-hardness region 60 and the low-hardness region 62 do not necessarily need to be provided on the common flat surface 56b of the restricting member 56. This assumes, for example, a case where a convex portion protruding toward the moving member 52 side is provided on the side portion 56a of the restricting member 56, the high-hardness region is provided on the convex portion, and the low-hardness region is provided at other locations.

[0092] The restricting member 56 has been described with an example of including a plurality of high-hardness regions 60 on which each of the plurality of moving members 52 slides. The number of these high-hardness regions 60 is not particularly limited. For example, when 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. Also, the number of high-hardness regions 60 of the restricting member 56 may be one. This assumes the case where the number of moving members 52 sliding on the restricting member 56 is one.

[0093] The partial quenching used when providing the high-hardness region 60 in the restricting member 56 may be realized by quenching performed outside the furnace such as high-frequency quenching in addition to laser quenching. In addition to this, this partial quenching may also be realized by quenching performed in a heating furnace in a state where parts other than the heat treatment part are masked by anti-carburizing treatment or the like. When providing the high-hardness region 60, after the partial quenching, finishing work for removing thermal distortion may be performed on the high-hardness region 60.

[0094] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the contents of the embodiments and modified forms. Many design changes such as changes, additions, and deletions of components are possible for the contents of the embodiments and modified forms. In the above-described embodiments, with regard to the contents for which such design changes are possible, the notation "embodiment" is added for emphasis. However, design changes are also permitted for the contents without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached. Also, the structures mentioned in the embodiments and modified forms naturally include those that can be regarded as the same considering manufacturing errors.

[0095] Any combination of the above components is also effective. For example, any explanatory matter of other embodiments may be combined with an embodiment, or any explanatory matter of an embodiment and other modified forms may be combined with a modified form.

Explanation of Reference Numerals

[0096] 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…Lateral 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

1. In a power transmission device, a moving member that moves by the rotation of a rotating shaft, and a regulating member that regulates the axial movement of the moving member, wherein the regulating member includes a high-hardness region on which the moving member slides and a low-hardness region having a surface hardness lower than that of the high-hardness region, the moving member includes a first moving member and a second moving member, and the high-hardness region includes a first high-hardness region on which the first moving member slides and a second high-hardness region on which the second moving member slides. A power transmission device.

2. 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.

3. The first moving member is a roller that penetrates an external gear, and the second moving member is the external gear. The power transmission device according to claim 2.

4. In a power transmission device, a moving member that moves by the rotation of a rotating shaft, and a regulating member that regulates the axial movement of the moving member, wherein the regulating member includes a high-hardness region on 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 that is disposed laterally in the axial direction with respect to the moving member and supports either a bearing or an oil seal is provided, and the regulating member is the side member itself or is integral with the side member. A power transmission device.

5. In a power transmission device, a moving member that moves by the rotation of a rotating shaft, and a regulating member that regulates the axial movement of the moving member, wherein the regulating member includes a high-hardness region on which the moving member slides and a low-hardness region having a surface hardness lower than that of the high-hardness region, and the high-hardness region is provided by laser hardening. A power transmission device.

6. The regulating member includes a side portion facing the moving member in the axial direction, and the high-hardness region and the low-hardness region are provided on the side portion. The power transmission device according to any one of claims 1 to 5.

7. The side portion has a flat surface, and the high-hardness region and the low-hardness region are provided on the common flat surface. The power transmission device according to claim 6.

8. The moving member slides on both the high-hardness region and the low-hardness region. The power transmission device according to claim 7.

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