Gear device

Abstract

To provide a gear device that can reduce a mechanical loss caused by sliding of a seal member.SOLUTION: A gear device 10 comprises a rotating body 16 comprising a pinion shaft 12, an outside member 18 arranged radially outside the rotating body 16, and a seal member 20 arranged between the rotating body 16 and the outside member 18. An inside diameter R20-1 of the seal member 20 is smaller than a tooth bottom diameter 12a-1 in a pinion part 12a of the pinion shaft 12. The gear device comprises a bearing 22 rotatably supporting the rotating body 16. An outside diameter R20-2 of the seal member 20 may be smaller than an inside diameter R22 of the bearing 22.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a gear device.

Background Art

[0002] Patent Document 1 discloses a gear device including a rotating body having a pinion shaft, a cover disposed on the radially outer side of the rotating body, and a seal member disposed between the cover and the rotating body. Under the structure of Patent Document 1, the inner diameter of the seal member is larger than the tip diameter of the pinion portion of the pinion shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a seal member is used, mechanical loss usually occurs due to the sliding of the seal member against the sliding partner (the rotating body in Patent Document 1). The inventor of the present application has recognized that there is room for improvement in the disclosed technology of Patent Document 1 in reducing this mechanical loss.

[0005] One object of the present disclosure is to provide a gear device capable of reducing mechanical loss due to the sliding of a seal member.

Means for Solving the Problems

[0006] A gear device including a rotating body having a pinion shaft, an outer member disposed on the radially outer side of the rotating body, and a seal member disposed between the outer member and the rotating body, wherein the inner diameter of the seal member is smaller than the root diameter of the pinion portion of the pinion shaft.

Effects of the Invention

[0007] According to the present disclosure, mechanical losses due to sliding of the seal member in the gear device can be reduced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the gear device of the present disclosure will be described. The same or equivalent elements 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 should be viewed in accordance with the orientation of the reference numerals.

[0010] Referring to FIG. 1, the gear device 10 is incorporated into the driven machine as a part of the driven machine. The driven machine is, for example, various machines such as industrial machines (machine tools, construction machines, etc.), robots (industrial robots, service robots, etc.), and transportation equipment (conveyors, vehicles, etc.).

[0011] The gear device 10 includes a high-speed rotating body 16 having a pinion shaft 12 and a transmission shaft 14 that can rotate integrally with the pinion shaft 12, an outer member 18 disposed radially outside the high-speed rotating body 16, a seal member 20 disposed between the high-speed rotating body 16 and the outer member 18, a bearing 22 that rotatably supports the high-speed rotating body 16, and a device main body 24 provided on the opposite side in the axial direction to the transmission shaft 14 with respect to the pinion shaft 12. The device main body 24 includes a low-speed rotating body 26, a power transmission mechanism 28 that transmits power between the high-speed rotating body 16 and the low-speed rotating body 26, and a support body 32 that is supported by an external support member and rotatably supports the low-speed rotating body 26 via a main bearing 30.

[0012] Hereinafter, the direction along the rotation center line C16 of the high-speed rotating body 16 is simply referred to as the axial direction, and with respect to the radial direction and the circumferential direction centered on the rotation center line C16, they are also simply referred to as the radial direction and the circumferential direction. Also, for convenience of explanation, one side in the axial direction (the left side of the paper surface in FIG. 1) is referred to as the load side, and the other side in the axial direction (the left side of the paper surface in FIG. 1) is referred to as the anti-load side.

[0013] In this embodiment, the high-speed rotating body 16 serves as an input member to which rotation is input from an external drive source, and the low-speed rotating body 26 serves as an output member that outputs rotation to an external driven member. The drive source is, for example, a motor, but in addition to this, a gear motor, an engine, etc. may also be used.

[0014] The power transmission mechanism 28 includes at least a transmission gear 34 that meshes with the pinion shaft 12. The power transmission mechanism 28 of this embodiment further includes a gear mechanism 36 provided on the power transmission path constituted by the power transmission mechanism 28. The power transmission mechanism 28 decelerates the rotation of the high-speed rotating body 16 and transmits it to the low-speed rotating body 26. The power transmission mechanism 28 of this embodiment performs primary deceleration by the transmission gear 34 that meshes with the pinion shaft 12, and performs secondary deceleration by the gear mechanism 36.

[0015] The high-speed rotating body 16, the outer member 18, the seal member 20, and the bearing 22 constitute a rotating body assembly 38 attached to the support 32 of the apparatus main body 24. In addition to these, the rotating body assembly 38 includes members (for example, regulation members 66A, 66B, etc. described later) attached to the high-speed rotating body 16 and the outer member 18. The apparatus main body 24 is constituted by the constituent members of the gear device 10 other than the rotating body assembly 38. The gear device 10 of the present embodiment is characterized by the configuration around the high-speed rotating body 16. First, the apparatus main body 24 will be described.

[0016] The gear device 10 of the present embodiment is a distribution type eccentric swing type gear device. This gear device 10 includes the above-described transmission gear 34, a plurality of crank shafts 42 having at least one eccentric portion 40 to which the transmission gear 34 is fixed by a spline structure or the like, a swing gear 44 swung by the eccentric portion 40, a meshing gear 46 meshing with the swing gear 44, carriers 50A, 50B that rotatably support the crank shaft 42 via a crank bearing 48, a pin body 52 that protrudes from the carriers 50A, 50B and penetrates the swing gear 44, and a casing 54 disposed on the radially outer side of the swing gear 44. In the present embodiment, the above-described low-speed rotating body 26 is the carriers 50A, 50B and the pin body 52, the power transmission mechanism 28 is the transmission gear 34, the crank shaft 42, the swing gear 44, and the meshing gear 46, and the support 32 is the casing 54. Further, the gear mechanism 36 is an eccentric swing type gear mechanism including the swing gear 44 and the meshing gear 46.

[0017] The number of transmission gears 34 in this embodiment is three, and only one of them is shown in the figure, but the number may be singular. The plurality of crankshafts 42 are arranged at intervals in the circumferential direction around the swing center C44A at positions offset in the radial direction of the swing gear 44 from the swing center C44A of the swing gear 44. The number of crankshafts 42 in this embodiment is three, and only one of them is shown in the figure. The axis C40 of the eccentric portion 40 of the crankshaft 42 is eccentric with respect to the rotation center line C42 of the crankshaft 42. The eccentric portion 40 can swing the swing gear 44 by rotating around the rotation center line C42 of the crankshaft 42. Here, "swing" means that the gear center C44B of the swing gear 44 rotates around the swing center C44A. The number of eccentric portions 40 is not particularly limited and may be either singular or three or more.

[0018] In this embodiment, the swing gear 44 is an external gear, and the meshing gear 46 is an internal gear. The swing gear 44 is individually provided corresponding to each of the plurality of eccentric portions 40 and is supported by the corresponding eccentric portion 40 via an eccentric bearing 56. The meshing gear 46 of this embodiment includes a meshing gear body 46a integrated with the casing 54 and a plurality of tooth portions 46b provided on the meshing gear body 46a and meshing with the swing gear 44. The plurality of tooth portions 46b may be integrally provided by the same member as the meshing gear body 46a or may be provided separately from the meshing gear body 46a.

[0019] The carriers 50A and 50B include a load-side carrier 50A provided on the load side and a counter-load-side carrier 50B provided on the counter-load side. Each of the carriers 50A and 50B is connected via a pin body 52 that penetrates the oscillating gear 44 using a knock pin 72 and a connecting bolt 74. The knock pin 72 and the connecting bolt 74 will connect the respective carriers 50A and 50B. The knock pin 72 connects the respective carriers 50A and 50B by positioning the load-side carrier 50A and the counter-load-side carrier 50B in the circumferential direction. To achieve this, the knock pin 72 of the present embodiment is inserted into a pin hole provided in a pin body 52 integrated with one of the load-side carrier 50A and the counter-load-side carrier 50B (here, the load-side carrier 50A) and a pin hole provided in the other thereof. In addition to this, the knock pin 72 may be inserted into a pin hole provided in one pin portion integrated with the load-side carrier 50A and a pin hole provided in the other pin portion integrated with the counter-load-side carrier 50B after axially dividing the pin body 52 to form a pair of pin portions. The connecting bolt 74 is screwed into a female screw hole provided in the pin body 52, and then the respective carriers 50A and 50B are connected by clamping the respective carriers 50A and 50B via the pin body 52. Here, an example is shown in which at least a part of the load-side carrier 50A and the pin body 52 are integrated, and the head of the connecting bolt 74 sits on the counter-load-side carrier 50B, but at least a part of the counter-load-side carrier 50B and the pin body 52 may be integrated, and the head of the connecting bolt 74 may sit on the load-side carrier 50A.

[0020] An example of the operation of the above-described gear device 10 will be described. When the high-speed rotating body 16 rotates due to the output of the drive source, the rotation of the high-speed rotating body 16 is transmitted to the crankshaft 42 via the pinion shaft 12 and the transmission gear 34 of the high-speed rotating body 16. When the crankshaft 42 rotates, the oscillating gear 44 oscillates due to the eccentric portion 40 of the crankshaft 42. When the oscillating gear 44 oscillates, the meshing position between the oscillating gear 44 and the meshing gear 46 changes in the circumferential direction. Along with this, every time the crankshaft 42 makes one rotation, either one of the oscillating gear 44 and the meshing gear 46 (here, the oscillating gear 44) rotates, and the rotation component thereof is taken out by the low-speed rotating body 26 (here, the carriers 50A and 50B and the pin body 52).

[0021] (Pinion shaft) Refer to FIGS. 1 and 2. The pinion shaft 12 includes a pinion portion 12a that meshes with the transmission gear 34, an insertion portion 12b that is integrally rotatably inserted into a shaft hole 14a provided in the transmission shaft 14, and an intermediate portion 12c provided between the pinion portion 12a and the insertion portion 12b. A plurality of tooth portions 12d that mesh with the transmission gear 34 are formed on the outer peripheral portion of the pinion portion 12a. The insertion portion 12b is provided on the side opposite to the load side with respect to the pinion portion 12a. Although the insertion portion 12b of the present embodiment shows an example of being integrally rotatable with the shaft hole 14a of the transmission shaft 14 by an interference fit, it may be integrally rotatable by a key structure, a spline structure, or the like. A part (insertion portion 12b) of the pinion shaft 12 is inserted into the shaft hole 14a of the transmission shaft 14 with an interference fit.

[0022] (Transmission shaft) The transmission shaft 14 has a role of connecting the pinion shaft 12 and the external shaft 60 and transmitting rotational power between the external shaft 60 and the pinion shaft 12. The external shaft 60 here is, for example, an output shaft for outputting the power of a drive source such as a motor shaft.

[0023] The transmission shaft 14 includes the aforementioned shaft hole 14a into which the insertion portion 12b of the pinion shaft 12 is integrally rotatably inserted, an external shaft connection portion 14b to which the external shaft 60 is connected, a bearing arrangement portion 14c where the bearing 22 is arranged, and a recess 14d provided between the shaft hole 14a and the bearing arrangement portion 14c.

[0024] The shaft hole 14a is provided at the load side end of the transmission shaft 14. The external shaft connection portion 14b is provided on the side opposite to the load side with respect to the shaft hole 14a of the transmission shaft 14. The external shaft connection portion 14b of the present embodiment has a cylindrical shape, and the shaft hole 14a is provided at its inner bottom portion. An external shaft 60 inserted from the side opposite to the load side is integrally rotatably connected to the inside of the external shaft connection portion 14b. The external shaft 60 is integrally rotatably connected using a connection structure such as a key structure or a spline structure, for example.

[0025] The bearing arrangement portion 14c of the present embodiment is provided on the outer peripheral portion of the flange portion 14e that protrudes radially outward and is provided on the load side portion of the transmission shaft 14. The outer diameter R14c (see FIG. 1) of the bearing arrangement portion 14c is larger than the outer diameter R14b of the external shaft connection portion 14b. Here, the outer diameter R14b of the external shaft connection portion 14b refers to the outer diameter at the location where it is the largest among the locations where the external shaft connection portion 14b is inserted.

[0026] The recess 14d is provided as a cutout portion for reducing the weight of the transmission shaft 14. The recess 14d of the present embodiment is provided at a location that overlaps radially with the outer peripheral portion of the flange portion 14e and the shaft hole 14a. The recess 14d includes an opening 14da that opens on the side surface portion on one axial side of the transmission shaft 14, and is provided so as to be recessed axially from the opening 14da. The recess 14d is provided so as to surround the periphery of the shaft hole 14a. Under the condition of satisfying this, the recess 14d of the present embodiment is continuously annular, but may be provided intermittently with an interval in the circumferential direction.

[0027] (Outer member) The outer member 18 of the present embodiment is a cover that covers the apparatus main body 24 from the non-load side. The outer member 18 includes a cover portion 18a that covers the apparatus main body 24 from the non-load side, a non-load side cylindrical portion 18b that protrudes from the inner peripheral side portion of the cover portion 18a to the non-load side, and a load side cylindrical portion 18c that protrudes from the outer peripheral side portion of the cover portion 18a to the load side and is attached to the apparatus main body 24. The cover portion 18a includes an inner flange portion 18d that protrudes radially inward more than the non-load side cylindrical portion 18b. The load side cylindrical portion 18c includes a fitting portion 18e that is in an inlay fit with the load side end portion of the support 32 of the apparatus main body 24. The load side cylindrical portion 18c is in an inlay fit with the load side end portion of the support 32 of the apparatus main body 24 and is then attached using bolts or the like (not shown). The attachment mode of the load side cylindrical portion 18c to the apparatus main body 24 is not particularly limited, and it may be attached using flange connection or the like. An O-ring 76 is disposed between the outer member 18 and the apparatus main body 24. Here, the O-ring 76 is disposed between the fitting portion 18e of the outer member 18 and the support 32 of the apparatus main body 24.

[0028] (Sealing member) The sealing member 20 seals an enclosed space 62 provided inside the gear device 10 and filled with a lubricant. The power transmission mechanism 28 of the gear device 10 is arranged in the enclosed space 62. The lubricant is, for example, lubricating oil, grease, etc. The enclosed space 62 is sealed by sealing members 64A, 64B, and 64C in addition to the sealing member 20. The sealing members 64A to 64C of the present embodiment include a first sealing member 64A arranged between the support 32 of the device body 24 and the low-speed rotating body 26 (load-side carrier 50A). In addition to this, the sealing members 64A to 64C include a second sealing member 64B that covers and closes the load-side end of the first hollow portion 24a (described later) of the device body 24, and a third sealing member 64C that covers and closes the load-side end of the second hollow portion 24b through which the crankshaft 42 is arranged and penetrates the device body 24. The first sealing member 64A is, for example, an oil seal, and the second and third sealing members 64B and 64C are, for example, seal caps.

[0029] The sealing member 20 is a contact-type seal that contacts both the outer member 18 and the high-speed rotating body 16. The sealing member 20 of the present embodiment will be described by taking an oil seal as an example, but its specific example is not particularly limited, and an O-ring or the like may also be used. The sealing member 20 includes a mounting portion 20a attached to the outer member 18 by interference fitting or the like, and a sliding portion 20b provided integrally with the mounting portion 20a and sliding on the high-speed rotating body 16. The mounting portion 20a of the present embodiment is attached to the inner peripheral portion of the inner flange portion 18d of the outer member 18. The sliding portion 20b is constituted by, for example, the seal lip portion of an oil seal. The outer member 18 serves as the mating member for mounting the sealing member 20, and the high-speed rotating body 16 serves as the mating member for sliding the sealing member 20. The contact portion between this mating member for sliding and the sealing member 20 becomes the sliding portion of the sliding portion 20b of the sealing member 20.

[0030] The bearing 22 is a rolling bearing such as a ball bearing or a roller bearing. The bearing 22 in this embodiment shows a deep groove ball bearing which is an example of a ball bearing, but its specific example is not particularly limited. The bearing 22 is disposed between the high-speed rotating body 16 and the outer member 18. The bearing 22 is supported by the outer member 18 and rotatably supports the high-speed rotating body 16. The bearing 22 in this embodiment is disposed inside the anti-load side cylindrical portion 18b of the outer member 18.

[0031] In addition to a plurality of rolling elements 22a, the bearing 22 includes an outer ring 22b and an inner ring 22c on which the plurality of rolling elements 22a roll. The bearing 22 in this embodiment includes a dedicated outer ring 22b separate from the outer member 18, but may be provided integrally with the outer member 18 by a part of the outer member 18. The outer ring 22b is attached to the outer member 18, for example, by interference fitting or the like. The bearing 22 in this embodiment includes a dedicated inner ring 22c separate from the high-speed rotating body 16, but may be provided integrally with the high-speed rotating body 16 by a part of the high-speed rotating body 16 (here, the transmission shaft 14). The inner ring 22c is attached to the transmission shaft 14, for example, by interference fitting or the like.

[0032] The axial movement of the outer ring 22b with respect to the outer member 18 is restricted by a first restricting member 66A such as a retaining ring provided on the anti-load side with respect to the outer ring 22b. The first restricting member 66A is attached, for example, by fitting into an annular groove provided in the inner peripheral portion of the anti-load side cylindrical portion 18b of the outer member 18. The axial movement of the inner ring 22c with respect to the transmission shaft 14 is restricted by a second restricting member 66B such as a retaining ring provided on the load side with respect to the inner ring 22c. The second restricting member 66B is attached to the transmission shaft 14 by fitting into an annular groove provided in the outer peripheral portion of the flange portion 14e of the transmission shaft 14.

[0033] Between the high-speed rotating body 16 and the outer member 18, a hollow space 70 communicating with the external space 68 is formed on the side opposite to the sealed space 62 with respect to the seal member 20, and a bearing 22 is disposed in the hollow space 70. The hollow space 70 of the present embodiment is axially separated from the sealed space 62 by the inner flange portion 18d of the outer member 18. If the bearing 22 is disposed on the side of the sealed space 62 rather than the seal member 20 between the high-speed rotating body 16 and the outer member 18, the flow of the lubricant is inhibited by the bearing 22, making it difficult for the lubricant to reach the seal member 20. In this regard, according to the present embodiment, the bearing 22 is disposed in the hollow space 70 on the side of the external space 68 rather than the seal member 20 between the high-speed rotating body 16 and the outer member 18. Therefore, a situation where the flow of the lubricant is inhibited by the bearing 22 does not occur, and the amount of the lubricant flowing to the seal member 20 can be increased. As a result, even when the seal member 20 is about to be heated due to frictional heat or the like at the sliding portion of the seal member 20, the high temperature of the seal member 20 can be suppressed by cooling with the lubricant.

[0034] The inner diameter R20-1 of the seal member 20 is smaller than the root diameter R12a-1 of the tooth bottom in the pinion portion 12a of the pinion shaft 12. The inner diameter R20-1 and the outer diameter R20-2 of the seal member 20 here are based on the state of contact with the high-speed rotating body 16 and the outer member 18. The root diameter R12a-1 here refers to the radius of a circle inscribed in the tooth bottom of the tooth portion 12d in the pinion portion 12a with the rotation center line C12 of the pinion shaft 12 as the center of the circle. On the premise of satisfying the condition of R20-1 < R12a-1, the seal member 20 of the present embodiment contacts the outer peripheral surface of the intermediate portion 12c of the pinion shaft 12. In addition to this, on the premise of satisfying this condition, the seal member 20 may contact the outer peripheral surface of the transmission shaft 14 at a position radially overlapping with the insertion portion 12b of the pinion shaft 12, for example.

[0035] The outer diameter R12c of the intermediate portion 12c is smaller than the root diameter R12a-1 of the pinion portion 12a. The advantages of this will be described. If the outer diameter R12c of the intermediate portion 12c ≥ the root diameter R12a-1 of the pinion portion 12a, when forming the tooth portion 12d on the pinion portion 12a with a tooth cutting tool, in addition to the pinion portion 12a, the portion of the intermediate portion 12c closer to the pinion portion 12a can be tooth cut. In this case, it is necessary to provide the contact portion of the seal member 20 at a position shifted toward the anti-load side from the tooth cut portion of the intermediate portion 12c, and the axial dimension of the entire pinion shaft 12 becomes unnecessarily long. In this regard, according to the present embodiment, by setting the outer diameter R12c of the intermediate portion 12c < the root diameter R12a-1 of the pinion portion 12a, when tooth cutting the pinion portion 12a with a tooth cutting tool, it is not necessary to tooth cut the intermediate portion 12c. Therefore, the contact portion of the seal member 20 can be made as close as possible to the pinion portion 12a, which is advantageous for reducing the axial dimension of the entire pinion shaft 12.

[0036] The outer diameter R20-2 of the seal member 20 is smaller than the inner diameter R22 of the bearing 22. In addition to this, the outer diameter R20-2 of the seal member 20 is smaller than the outer diameter R14b of the external shaft connection portion 14b of the transmission shaft 14. Also, the inner diameter R22 of the bearing 22 is larger than the tip diameter R12a-2 of the pinion portion 12a of the pinion shaft 12. The tip diameter R12a-2 here refers to the radius of the circle that circumscribes the tooth tip of the tooth portion 12d in the pinion portion 12a with the rotation center line C12 of the pinion shaft 12 as the center of the circle.

[0037] The effects of the above-described gear device 10 will be described.

[0038] (A) The inner diameter R20-1 of the seal member 20 is smaller than the root diameter R12a-1 of the pinion portion 12a of the pinion shaft 12. Therefore, when the inner diameter R20-1 of the seal member 20 is made larger than the tip diameter R12a-2 of the pinion shaft 12 while maintaining the radial dimension of the seal member 20, the diameter of the sliding portion of the seal member 20 with respect to the sliding partner (here, the high-speed rotating body 16) can be reduced. As a result, by reducing the peripheral speed difference between the seal member 20 and the sliding partner at the sliding portion of the seal member 20, the mechanical loss due to the sliding can be reduced.

[0039] The outer diameter R20-2 of the seal member 20 is smaller than the inner diameter R22 of the bearing 22. Therefore, when the seal member 20 is attached to the outer member 18 as in the present embodiment, the press-fitting force when press-fitting the seal member 20 into the planned attachment position of the outer member 18 can be reduced compared to when the outer diameter R20-2 of the seal member 20 becomes equal to or larger than the inner diameter R22 of the bearing 22, and the workability is improved. Also, different from the present embodiment, when the seal member 20 slides on the outer member 18, the diameter of the sliding portion of the seal member 20 with respect to the outer member 18 can be reduced compared to when the outer diameter R20-2 of the seal member 20 becomes equal to or larger than the inner diameter R22 of the bearing 22, and the mechanical loss due to the sliding can be further reduced. In particular, when the overall outer diameter of the high-speed rotating body 16 is reduced for good workability or reduction of mechanical loss, downsizing the bearing 22 causes a decrease in bearing capacity, but this can be avoided, which is advantageous.

[0040] If the seal member 20 is disposed at a location that overlaps with the insertion portion 12b of the pinion shaft 12 in the radial direction, since the transmission shaft 14 is present between the seal member 20 and the pinion shaft 12, the inner diameter R20-1 of the seal member 20 becomes large. In this regard, the seal member 20 of the present embodiment is in contact with the intermediate portion 12c of the pinion shaft 12. Therefore, when the seal member 20 is disposed at a location that overlaps with the insertion portion 12b of the pinion shaft 12 in the radial direction while maintaining the radial dimension of the seal member 20, the inner diameter R20-1 of the seal member 20 can be made smaller than in the case where the seal member 20 is disposed at a location that overlaps with the insertion portion 12b of the pinion shaft 12 in the radial direction. As a result, compared with the case where the seal member 20 is disposed in this way, the diameter of the sliding portion of the seal member 20 with respect to the sliding partner (here, the high-speed rotating body 16) can be made smaller, and the mechanical loss due to the sliding can be reduced. In particular, if the entire high-speed rotating body 16 is reduced in outer diameter in order to reduce mechanical loss, reducing the outer diameter of the bearing 22 will cause a reduction in bearing capacity, but this can be avoided, which is advantageous.

[0041] The transmission shaft 14 includes a concave portion 14d that serves as a cutout portion between the shaft hole 14a and the bearing arrangement portion 14c. Therefore, the inertia of the transmission shaft 14 can be reduced compared with the case where the transmission shaft 14 does not have the concave portion 14d. From this viewpoint, the bottom portion 14db of the concave portion 14d is preferably located on the side opposite to the opening portion 14da in the axial direction (here, the anti-load side) with respect to the axial center position C22 of the bearing 22.

[0042] When the outer diameter R14c of the bearing arrangement portion 14c of the transmission shaft 14 is larger than the outer diameter R14b of the external shaft connection portion 14b, due to the increase in the outer diameter of the transmission shaft 14 around the bearing arrangement portion 14c (around the flange portion 14e) of the transmission shaft 14, its inertia tends to increase. Even in this case, it is advantageous in that the inertia can be reduced by the concave portion 14d of the transmission shaft 14. In particular, if the entire transmission shaft 14 is reduced in outer diameter in order to reduce inertia, reducing the outer diameter of the bearing 22 will cause a reduction in bearing capacity, but this can be avoided, which is advantageous. The effect of being advantageous in this regard also applies to the configuration in the previous paragraph.

[0043] Next, other features of the gear device 10 will be described. Refer to FIGS. 2 and 3. The insertion portion 12b of the pinion shaft 12 includes a base-end side shaft portion 12ba and a tip-end side shaft portion 12bb provided on the tip-end side of the base-end side shaft portion 12ba. The shaft hole 14a of the transmission shaft 14 includes a base-end side hole portion 14aa into which the base-end side shaft portion 12ba of the pinion shaft 12 is inserted, and a tip-end side hole portion 14ab into which the tip-end side shaft portion 12bb is inserted. The outer diameter R12ba of the base-end side shaft portion 12ba of the pinion shaft 12 is larger than the outer diameter R12bb of the tip-end side shaft portion 12bb. The inner diameter R14aa of the base-end side hole portion 14aa of the transmission shaft 14 is larger than the inner diameter R14ab of the tip-end side hole portion 14ab. These outer and inner diameters are based on the state where the pinion shaft 12 is not press-fitted into the shaft hole 14a.

[0044] Note that the axial dimension of the base-end side shaft portion 12ba is smaller than the axial dimension of the tip-end side shaft portion 12bb. Also, the axial dimension of the base-end side hole portion 14aa is smaller than the axial dimension of the tip-end side hole portion 14ab.

[0045] The base-end side shaft portion 12ba is press-fitted into the base-end side hole portion 14aa with a first interference fit, and the tip-end side shaft portion 12bb is press-fitted into the tip-end side hole portion 14ab with a second interference fit. The first interference fit is represented by the outer diameter R12ba of the base-end side shaft portion 12ba - the inner diameter R14aa of the base-end side hole portion 14aa (outer diameter R12ba > inner diameter R14aa). The second interference fit is represented by the outer diameter R12bb of the tip-end side shaft portion 12bb - the inner diameter R14ab of the tip-end side hole portion 14ab (outer diameter R12bb > inner diameter R14ab).

[0046] In this embodiment, by setting the first tightening allowance to be larger than the second tightening allowance, i.e., the first tightening allowance > the second tightening allowance, when inserting the pinion shaft 12 into the shaft hole 14a, the insertion resistance when inserting the tip-side shaft portion 12bb into the tip-side hole portion 14ab can be suppressed as compared with the case where the second tightening allowance is made the same as the first tightening allowance. Further, by inserting the tip-side shaft portion 12bb into the tip-side hole portion 14ab to align the radial position of the pinion shaft 12 with respect to the shaft hole 14a, the base-end-side shaft portion 12ba with a larger tightening allowance can be easily inserted into the base-end-side hole portion 14aa, and the workability during the insertion operation is improved. Also, as compared with the case where the first tightening allowance is made the same as the second tightening allowance, the fixing degree of the pinion shaft 12 with respect to the transmission shaft 14 at the location of the first tightening allowance can be increased.

[0047] In addition to this, the insertion portion 12b of the pinion shaft 12 includes a tip-side tapered portion 12bc provided on the tip side of the tip-side shaft portion 12bb and having an outer diameter that decreases toward the tip side, and a base-end-side tapered portion 12bd provided on the base-end side of the base-end-side shaft portion 12ba and having an outer diameter that decreases toward the tip side.

[0048] Note that the relationship between the respective tightening allowances is not particularly limited, and either the first tightening allowance = the second tightening allowance or the first tightening allowance < the second tightening allowance may be used. Also, in the insertion portion 12b of the pinion shaft 12 and the shaft hole 14a of the transmission shaft 14, in addition to the portions that are interference-fitted with the first tightening allowance and the portions that are interference-fitted with the second tightening allowance, there may be portions that are interference-fitted with a tightening allowance different from these. Further, in this embodiment, the outer diameters of the respective portions of the pinion shaft 12 are as follows. The relationship between the outer diameters and the axial dimensions of the respective portions of the pinion shaft 12 listed here is merely an example, and other conditions may also be applicable. The root diameter R12a-1 of the tooth bottom of the pinion portion 12a > the outer diameter R12c of the intermediate portion 12c > the outer diameter R12ba of the base-end-side shaft portion 12ba of the insertion portion 12b > the outer diameter R12bb of the tip-side shaft portion 12bb of the insertion portion 12b

[0049] A slip prevention structure 80 is provided in at least a part of the axial range of the interference fit portions of the pinion shaft 12 and the transmission shaft 14. Here, the interference fit portion of the pinion shaft 12 is the insertion portion 12b (the proximal end side shaft portion 12ba and the distal end side shaft portion 12bb) of the pinion shaft 12 described above, and the interference fit portion of the transmission shaft 14 is a part of the shaft hole 14a (the proximal end side hole portion 14aa and the distal end side hole portion 14ab) described above.

[0050] The slip prevention structure 80 of the present embodiment is constituted by a knurled portion provided in a part of the axial range of the pinion shaft 12 at the interference fit portion. In the present embodiment, the slip prevention structure 80 is provided on the proximal end side shaft portion 12ba of the pinion shaft 12 and is not provided on other parts (such as the distal end side shaft portion 12bb) of the insertion portion 12b. The knurled portion is constituted by forming a plurality of minute knurled grooves by knurling. The knurled portion of the present embodiment has a plain pattern in which the knurled grooves along the axial direction are arranged in the circumferential direction. In addition to this, the knurled portion may have a twill pattern in which knurled grooves inclined with respect to the axial direction are provided in a net shape, and the specific pattern is not particularly limited.

[0051] When the slip prevention structure 80 is constituted by the knurled portion, a part of the mating member (here, the transmission shaft 14) that is interference-fitted into the knurled groove bites in, thereby exerting a slip prevention effect. In the present embodiment, since the slip prevention structure 80 is constituted by the knurled portion with a plain pattern, the slip prevention effect in the circumferential direction is exerted, so that the fixing degree in the circumferential direction can be increased. In addition to this, when the slip prevention structure 80 is constituted by a knurled portion with a twill pattern or the like, the slip prevention effect in the circumferential direction and the axial direction is exerted, so that the fixing degree in the circumferential direction and the axial direction can be increased. In particular, when the slip prevention effect in the circumferential direction and the axial direction can be exerted, when a moment load acts on the transmission shaft 14, by increasing the fixing degree in the axial direction by the slip prevention structure 80, it is advantageous in that the pinion shaft 12 can be prevented from coming out of the shaft hole 14a.

[0052] With such an anti-slip structure 80, the degree of fixation at the interference fit portion between the pinion shaft 12 and the transmission shaft 14 can be increased as compared with the case where there is no anti-slip structure 80. In particular, when a concave portion 14d serving as a cutout portion is provided around the shaft hole 14a of the transmission shaft 14, the tightening of the transmission shaft 14 against the pinion shaft 12 tends to become loose, and the degree of fixation at the interference fit portion tends to decrease. In such a case, it is advantageous in that the degree of fixation can be increased.

[0053] In addition, the anti-slip structure 80 may be provided over the entire insertion portion 12b of the pinion shaft 12, or may be provided on a part or all of the shaft hole 14a of the transmission shaft 14. The specific example of the anti-slip structure 80 is not particularly limited, and in addition to the knurled portion, it may be constituted by a surface treatment layer provided on the surface portion of at least one of the pinion shaft 12 and the transmission shaft 14. The surface treatment layer has a larger surface roughness than the base material constituting one of the pinion shaft 12 and the transmission shaft 14. This surface treatment layer may be obtained by performing a surface treatment (such as shot peening) for roughening the surface roughness on the surface of the base material. When the anti-slip structure 80 is constituted by such a surface treatment layer, the anti-slip effect in the circumferential direction and the axial direction is exhibited.

[0054] Refer to FIG. 1. The gear device 10 includes a first hollow portion 24a provided in the device main body 24 and penetrating in the axial direction. The first hollow portion 24a of the present embodiment is constituted by through holes individually formed in the central portions of the carriers 50A, 50B and the swing gear 44. The internal space of the first hollow portion 24a is provided at a position overlapping the pinion shaft 12 in the axial direction. Thereby, as will be described later, during the assembly process of the gear device 10, by moving the inside of the first hollow portion 24a of the device main body 24 axially toward the transmission shaft 14 side, the pinion shaft 12 can be inserted into the shaft hole 14a of the transmission shaft 14 from the load side. In the present embodiment, a part of the load side of the pinion shaft 12 is disposed inside the first hollow portion 24a.

[0055] Next, the assembly method of the gear device 10 will be described. This assembly method has, for example, two patterns: the first pattern and the second pattern described below. First, the assembly method of the first pattern will be described.

[0056] Refer to FIG. 4. In the assembling method of the first pattern, first, a first preparation step is performed to prepare a sub-assembly 90 including an outer member 18 and a transmission shaft 14 supported by the outer member 18 via a bearing 22. Here, the range of the sub-assembly 90 obtained by the first preparation step is indicated by reference numerals. In the first preparation step, a first sub-step is performed to attach a seal member 20 to the outer member 18. In the first preparation step, before and after the first sub-step, a second sub-step is performed to attach an inner ring 22c of the bearing 22 to a bearing arrangement portion 14c of the transmission shaft 14 by interference fit and then attach a second restricting member 66B for restricting the axial movement of the bearing 22 to the transmission shaft 14. At this time, a bearing 22 in which rolling elements 22a and an outer ring 22b are assembled to the inner ring 22c is used. In the first preparation step, a third sub-step is performed to attach an outer ring 22b of the bearing 22 to the anti-load side cylindrical portion 18b of the outer member 18 obtained in the first sub-step by interference fit and then attach a first restricting member 66A for restricting the axial movement thereof to the outer member 18. Thereby, the aforementioned sub-assembly 90 is obtained.

[0057] In the assembling method of the first pattern, next, a second preparation step is performed to incorporate the device body 24 into the sub-assembly 90 by attaching the outer member 18 of the sub-assembly 90 to a support 32 of the device body 24.

[0058] In the assembling method of the first pattern, next, as shown in FIG. 4, an insertion step is performed in which the pinion shaft 12 is moved axially toward the transmission shaft 14 within a first hollow portion 24a of the device body 24 and then the pinion shaft 12 is inserted into a shaft hole 14a of the transmission shaft 14. After this, although not shown, the gear device 10 can be obtained by attaching a second sealing member 64B to the first hollow portion 24a of the device body 24.

[0059] Next, the assembly method of the second pattern will be described. Refer to FIG. 5. In this assembly method as well, the first preparation step of preparing the aforementioned sub-assembly 90 is performed. In this assembly method, next, an insertion step of inserting the pinion shaft 12 into the shaft hole 14a of the transmission shaft 14 of the sub-assembly 90 is performed. This insertion step will be carried out before attaching the outer member 18 of the sub-assembly 90 to the apparatus main body 24.

[0060] Refer to FIG. 6. After that, an attachment step of attaching the outer member 18 of the sub-assembly 90 to the support 32 of the apparatus main body 24 is performed. In the case of this assembly method of the second pattern, when the first hollow portion 24a is provided in the apparatus main body 24 as in the present embodiment, the second sealing member 64B may be attached to the first hollow portion 24a at an arbitrary timing.

[0061] The modified forms of the above gear device will be described.

[0062] In the embodiment, an example in which the high-speed rotating body 16 is the input member and the low-speed rotating body 26 is the output member has been described. In this case, the gear device 10 functions as a speed reduction device that reduces the rotation input to the high-speed rotating body 16 and outputs it from the low-speed rotating body 26. Instead of this, the high-speed rotating body 16 may be the output member and the low-speed rotating body 26 may be the input member. In this case, the gear device 10 functions as a speed increase device that increases the rotation input to the low-speed rotating body 26 and outputs it from the high-speed rotating body 16. In this case, the power transmission mechanism 28 will increase the rotation of the low-speed rotating body 26 and transmit it to the high-speed rotating body 16.

[0063] The apparatus main body 24 does not necessarily have to be provided with the first hollow portion 24a. A specific example of the power transmission mechanism 28 of the apparatus main body 24 is not particularly limited. For example, the gear mechanism 36 of the power transmission mechanism 28 may cooperate with the pinion shaft 12 to form a simple planetary gear mechanism. Specifically, the pinion shaft 12 may be used as a sun gear, and in addition to the transmission gear 34 as a planetary gear, the gear mechanism 36 may be provided with an internal gear that meshes with the planetary gear. In addition to this, the gear mechanism 36 may form an eccentric swing type gear mechanism such as a center crank type. When the gear mechanism 36 is an eccentric swing type gear mechanism, an internal gear may be used as the swing gear 44 instead of the external gear, and an external gear may be used as the meshing gear 46 instead of the internal gear.

[0064] Specific examples of the low-speed rotating body 26 and the support 32 of the apparatus main body 24 are not particularly limited. For example, instead of the carrier and the pin body 52, the casing 54 may be the low-speed rotating body 26, and the carrier and the pin body 52 may be the support 32. Further, the low-speed rotating body 26 may be a rotating shaft that rotates integrally with the transmission gear 34.

[0065] The outer diameter R14c of the bearing arrangement portion 14c of the transmission shaft 14 may be equal to or less than the outer diameter R14b of its external shaft connection portion 14b. The transmission shaft 14 does not necessarily have to be provided with the recess 14d that serves as a hollowed-out portion. The recess 14d may open not only on the side surface portion on the load side of the transmission shaft 14 but also on the side surface portion on the opposite side of the load. In either case, it may open on the flange portion 14e of the transmission shaft 14.

[0066] The attachment portion 20a of the seal member 20 may be attached to the high-speed rotating body 16 instead of the outer member 18, and its sliding portion 20b may slide on the outer member 18 instead of the high-speed rotating body 16. It can also be said that the seal member 20 may be attached with one of the high-speed rotating body 16 and the outer member 18 as the attachment partner and slide with the other as the sliding partner. Even when the seal member 20 slides on the outer member 18, the effect of (A) described above can be obtained. The outer diameter R20-2 of the seal member 20 may be equal to or greater than the inner diameter R22 of the bearing 22.

[0067] The interference fit portions of the pinion shaft 12 and the transmission shaft 14 may not be provided with an anti-slip structure 80.

[0068] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the content of the embodiments and modified forms. Many design changes such as changes, additions, and deletions of components are possible for the content of the embodiments and modified forms. In the foregoing embodiments, with regard to the content for which such design changes are possible, the notation "embodiment" is added for emphasis. However, design changes are also permitted for the content without such notation. The hatching attached to the cross-section of the drawings does not limit the material of the object to which the hatching is attached. Structures and numerical values mentioned in the embodiments and modified forms naturally include those that can be regarded as the same considering manufacturing errors and the like. Components configured by a single member in the embodiments may be configured by a plurality of members. Similarly, components configured by a plurality of members in the embodiments may be configured by a single member.

Description of Reference Numerals

[0069] 10... gear device, 12... pinion shaft, 12a... pinion part, 12b... insertion part, 12c... intermediate part, 14... transmission shaft, 14a... shaft hole, 14b... external shaft connection part, 14c... bearing arrangement part, 14d... recess, 16... rotating body (high-speed rotating body), 18... outer member, 20... seal member, 22... bearing, 24... device body, 24a... hollow part, 60... external shaft, 80... anti-slip structure.

Claims

1. A rotating body having a pinion shaft, An outer member disposed radially outside the rotating body, A gear device including a seal member disposed between the outer member and the rotating body, wherein The inner diameter of the seal member is smaller than the root diameter of the pinion portion of the pinion shaft.

2. The gear device according to claim 1, further comprising a bearing that rotatably supports the rotating body, wherein The outer diameter of the seal member is smaller than the inner diameter of the bearing.

3. The rotating body includes a transmission shaft, The pinion shaft includes an insertion portion that is integrally rotatably inserted into a shaft hole provided in the transmission shaft, and an intermediate portion provided between the pinion portion and the insertion portion, and The gear device according to claim 1, wherein the seal member contacts the intermediate portion.

4. The gear device according to claim 1, further comprising a bearing that rotatably supports the rotating body, The rotating body includes a transmission shaft, The transmission shaft includes a shaft hole into which a part of the pinion shaft is integrally rotatably inserted, a bearing arrangement portion where the bearing is disposed, and a recess provided between the shaft hole and the bearing arrangement portion.

5. The transmission shaft includes an external shaft connection portion to which an external shaft is connected, and The gear device according to claim 4, wherein the outer diameter of the bearing arrangement portion is larger than the outer diameter of the external shaft connection portion.

6. The rotating body includes a transmission shaft in which a part of the pinion shaft is press-fitted, and The gear device according to claim 1, wherein an anti-slip structure is provided in at least a part of the axial range of the press-fitting portion of the pinion shaft and the transmission shaft.

7. The rotating body includes a transmission shaft into which a part of the pinion shaft is integrally rotatably inserted, The gear device includes a device body provided on the side opposite to the transmission shaft in the axial direction with respect to the pinion shaft, A hollow portion penetrating in the axial direction is provided in the device body, and The gear device according to claim 1, wherein the internal space of the hollow portion is provided at a position overlapping the pinion shaft in the axial direction.

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