Gear device

Abstract

The invention provides a gear device. A speed reduction mechanism (4) according to one embodiment of the present invention is provided with: a sun gear (30) having external teeth (32) at an end; a crankshaft (13) provided parallel to the sun gear (30); a transmission spur gear (14) that is provided integrally with the crankshaft (13) at an end of the crankshaft (13) and meshes with the external teeth (32); and an intermediate spur gear which is supported at the end of the crankshaft (13) so as to be rotatable relative to the crankshaft (13) and which meshes with the external teeth (32).

Description

Technical Field

[0001] This invention relates to a gear mechanism. Background Technology

[0002] Traditionally, gear mechanisms have been known to include eccentric oscillating type reduction gears. Such gear mechanisms include: an internal gear (outer cylinder); a gear carrier rotatably supported on the internal gear by bearings; multiple crankshafts rotatably supported on the gear carrier, each having an eccentric portion; and an external gear housed within the gear carrier. Driven components, such as robotic arms, are fastened to the gear carrier using multiple bolts. These bolts are arranged along the outer periphery of the gear carrier.

[0003] Multiple crankshafts are arranged circumferentially. Crankshaft gears are provided at the axial ends of each crankshaft.

[0004] The external gear is rotatably supported on the crankshaft and meshes with the internal gear. A through-hole is formed radially inside the gear carrier and the external gear. A cylindrical central shaft (cylinder) is inserted into this hole. A spur gear that meshes with the crankshaft gear is located at the axial end of the central shaft.

[0005] In addition to the crankshaft gear, the intermediate gear also meshes with the spur gear. The intermediate gear is positioned between the crankshaft gears arranged circumferentially. The input gear, which rotates as driven by the electric motor, meshes with the intermediate gear.

[0006] Based on this structure, when the electric motor is driven, the central shaft rotates via the input gear and the intermediate gear. The rotation of the central shaft is transmitted to the crankshaft via the spur gear and the crankshaft gear. As the crankshaft rotates, the external gear oscillates while meshing with the internal gear. Due to the oscillating rotation of the external gear, the gear carrier rotates via the crankshaft. Thus, the rotation of the input gear, which rotates with the drive of the electric motor, is decelerated and output from the gear carrier. With the internal gear fixed, the driven component fixed to the gear carrier is driven. Even with the gear carrier fixed, the internal gear can also be used as an output.

[0007] An eccentric oscillating type speed reducer temporarily transmits the rotation of the input gear to the central shaft via an intermediate gear, thereby ensuring equal load distribution on each crankshaft. Furthermore, by providing the intermediate gear, the axis of the input gear can be offset from the axis of the central shaft (gear carrier). This allows, for example, a cable to be wound onto the central shaft. Therefore, the layout of the speed reducer can be made more flexible, or space can be saved when configuring the speed reducer.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 5231530 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] In the aforementioned prior art, spur gears, crankshaft gears, intermediate gears, and input gears that constitute multiple power transmission paths are arranged at the axial end of the reduction gear. Therefore, it is necessary to ensure sufficient space for arranging these gears, resulting in a problem where the axial end of the reduction gear cannot be effectively and flexibly utilized.

[0013] Furthermore, ensuring sufficient space for accommodating multiple gears at the axial end of the reduction gear makes it difficult to adequately secure space for fixing the driven component within the gear carrier. Consequently, there are limitations in the ability to securely fix the gear carrier and the driven component.

[0014] The present invention provides a gear device that can arrange gears that form multiple power transmission paths in a space-saving manner, and can securely fix and support components and other components that are provided with the transmission paths.

[0015] Solution for solving the problem

[0016] One aspect of the gear device of the present invention comprises: a first shaft having teeth at its end; a second shaft disposed parallel to the first shaft; a first gear integrally disposed at the end of the second shaft and meshing with the teeth; and a second gear supported at the end of the second shaft in a manner rotatable relative to the second shaft and meshing with the teeth.

[0017] With this configuration, the gear mechanism can be arranged in a space-saving manner when viewed from the axial direction of the first and second shafts. The gear mechanism has multiple power transmission paths that transmit power in the order of the second gear, the external gear and the first shaft, and the first gear and the second shaft.

[0018] As a result, sufficient space can be ensured for fixing to other components in the component that supports the first and second shafts to rotate freely. Therefore, fixing parts such as internal threads can be adequately provided in this space. Consequently, the component that supports the first and second shafts to rotate freely and other components (driven components) can be securely fixed.

[0019] In the above structure, the gear device includes: an internal gear having internal teeth on its inner circumferential surface; a gear carrier disposed radially inside the internal gear and supported on the internal gear in a manner rotatable relative to the internal gear; a fixing portion disposed along the outer circumference of the gear carrier for fixing the gear carrier and other components; a first shaft disposed coaxially with the gear carrier at its radial center and supported on the gear carrier in a manner rotatable relative to the gear carrier; a plurality of second shafts rotatably supported on the gear carrier and disposed around the first shaft; and an external gear housed in the gear carrier and meshing with the internal teeth. The second shaft has: a shaft body; and an eccentric portion disposed on the shaft body, eccentric relative to the axis of rotation of the shaft body, the external gear being rotatably supported on the eccentric portion, and the second gear being disposed on one of the plurality of second shafts.

[0020] In the above structure, the first gear and the second gear are arranged axially, and the second gear is supported on the second shaft by means of a bearing.

[0021] The effects of the invention

[0022] The aforementioned gear device can save space by arranging gears that form multiple power transmission paths, thereby enabling the component that supports the gears with the transmission paths to be securely fixed. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the deceleration device in an embodiment of the present invention.

[0024] Figure 2 yes Figure 1 View II.

[0025] Figure 3 yes Figure 1 Enlarged view of Part III.

[0026] Figure 4 This is an enlarged cross-sectional view of the intermediate spur gear and its surrounding area in the first modified embodiment of the present invention.

[0027] Figure 5 This is an enlarged cross-sectional view of the intermediate spur gear and its surrounding area in the second variation of the embodiment of the present invention.

[0028] Figure 6 This is an enlarged cross-sectional view of the intermediate spur gear and its surrounding area in the third variation of the embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1. Reduction gear (gear assembly); 2. Housing (internal gear); 3. Gear carrier; 4. Reduction mechanism (gear assembly); 5. Internal tooth pin (internal tooth); 12. Mounting internal thread part (fixed part); 13. Crankshaft (second shaft); 13a. Shaft body; 13b. First eccentric part (eccentric part); 13c. Second eccentric part (eccentric part); 14. Transmission spur gear (first gear); 15. First external gear (external gear); 16. Second external gear (external gear); 30. Center gear (first shaft); 32. External tooth (tooth part); 50. Intermediate spur gear (second gear). Detailed Implementation

[0031] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0032] <Driver>

[0033] Figure 1 This is a cross-sectional view of the speed reduction device 1.

[0034] like Figure 1 As shown, the reduction gear 1 is a so-called eccentric oscillating type reduction gear. The reduction gear 1 is mounted on a driven component (or other component), such as a robotic arm (not shown). The reduction gear 1 drives the driven component by reducing the rotational speed of an electric motor (not shown). The reduction gear 1 includes: a cylindrical housing 2; a gear carrier 3 rotatably disposed radially inside the housing 2; and a reduction mechanism (an example of the gear device in the claims) 4 connected to the gear carrier 3. The central axis of the housing 2 coincides with the rotational axis of the gear carrier 3.

[0035] In the following description, these central axes and axes of rotation are generally referred to as the first axis of rotation A1. The direction parallel to the first axis of rotation A1 is called the axial direction. The direction of rotation of the gear carrier 3 is called the circumferential direction. The radial direction of the housing 2, which is orthogonal to the axial and circumferential directions, is simply referred to as the radial direction. The central side of the axial direction of the housing 2 is called the central side of the axial direction. The side of the axial direction opposite to the central side is called the outer side of the axial direction.

[0036] <Shell>

[0037] The housing 2 is formed of, for example, spheroidal graphite cast iron. For example, FCD450 is used as the spheroidal graphite cast iron. An outer flange 2a extending radially outward is integrally formed on the outer peripheral surface of the housing 2. A plurality of bolt holes 2b are formed in the outer flange 2a. The bolt holes 2b are arranged at equal intervals in the circumferential direction. These outer flanges 2a and bolt holes 2b are used to secure the reduction gear 1 (housing 2) to a driven component (not shown).

[0038] Multiple pin grooves 2e are formed along the axial direction on the inner circumferential surface 2d of the housing 2. The pin grooves 2e are arranged at equal intervals in the circumferential direction. An internal toothed pin 5 is embedded in each pin groove 2e. The internal toothed pin 5 functions as internal teeth that mesh with the external gears 15 and 16, which will be discussed later in the reduction mechanism 4. The gear carrier 3 is rotatably supported on the housing 2 by means of the main bearings 41 and 42.

[0039] <Gear Carrier>

[0040] The gear carrier 3 includes a circular plate-shaped base plate portion 7 and an end plate portion 8 arranged opposite each other in the axial direction. The base plate portion 7 and the end plate portion 8 are formed of, for example, spheroidal graphite cast iron. For example, FCD450 is used as spheroidal graphite cast iron.

[0041] <Substrate part>

[0042] Figure 2 yes Figure 1 View II.

[0043] like Figure 1 , Figure 2 As shown, the substrate portion 7 is formed in the shape of a circular plate. A sealing portion 24 is provided between the outer peripheral surface 7a of the substrate portion 7 and the inner peripheral surface 2d of the housing 2, at a position opposite to the end plate portion 8, relative to the first main bearing 41. The sealing between the substrate portion 7 and the housing 2 is ensured by the sealing portion 24.

[0044] A substrate shaft insertion hole 7d is formed in the radial center of the substrate portion 7. A bearing retaining surface 7f is formed in the axial center of the substrate shaft insertion hole 7d.

[0045] A plurality of crankshaft insertion holes 7g are formed around the substrate shaft insertion hole 7d in the substrate portion 7. Each crankshaft insertion hole 7g is arranged at equal intervals in the circumferential direction.

[0046] On the first end face 7h of the substrate portion 7, opposite to the end plate portion 8, a central recess 9 is formed coaxially with the substrate shaft insertion hole 7d. The central recess 9 is circular in shape when viewed axially. The radius of the central recess 9 is slightly larger than the distance between the axis of the substrate shaft insertion hole 7d and the axis of the crankshaft insertion hole 7g. The central recess 9 communicates with the substrate shaft insertion hole 7d.

[0047] On the first end face 7h of the base plate portion 7, a gear receiving recess 10 is formed coaxially with each crankshaft insertion hole 7g. The gear receiving recess 10 communicates with the central recess 9. The gear receiving recess 10 is formed in an arc shape extending radially outward from the outer periphery of the central recess 9, with the axis of the crankshaft insertion hole 7g as the center. The gear receiving recess 10 communicates with the crankshaft insertion hole 7g. The external gear (an example of the tooth portion in the claim) 32 and the transmission spur gear (an example of the first gear in the claim) 14, which will be discussed later, are housed in these central recesses 9 and gear receiving recesses 10.

[0048] On the first end face 7h of the base plate 7, a plurality of mounting internal threads 12 are formed around the central recess 9. In other words, the plurality of mounting internal threads 12 are formed on the outer periphery of the first end face 7h of the base plate 7 and along the entire surface between the circumferentially adjacent gear receiving recesses 10. The mounting internal threads 12 are used to fix the reduction gear 1 (gear carrier 3) to the driven member (not shown). That is, the driven member (not shown) is fixed to the gear carrier 3 by tightening the bolts (not shown) to each mounting internal thread 12.

[0049] Three pillars 11 are formed on the second end face 7i of the base plate portion 7 on the side near the end plate portion 8, protruding toward the end plate portion 8. Each pillar 11 is disposed between crankshaft insertion holes 7g that are adjacent in the circumferential direction. The three pillars 11 are arranged at equal intervals in the circumferential direction.

[0050] Each of the pillar portions 11 has a plurality of (e.g., two) internal thread portions 26 and pin holes 27 formed on its top surface 11a. These internal thread portions 26 and pin holes 27 are used to integrate the base plate portion 7 and the end plate portion 8 (details will be discussed later).

[0051] A bearing 20 is provided on the bearing retaining surface 7f of the substrate portion 7. The bearing 20 is, for example, a ball bearing. That is, the outer ring 20a of the bearing 20 is fitted into the bearing retaining surface 7f.

[0052] A cylindrical central gear (an example of the first shaft in the claim) 30 is fitted into the inner ring 20b of the bearing 20. The central gear 30 has a cylindrical portion 31 and external teeth 32 integrally formed with the outer peripheral surface of the cylindrical portion 31.

[0053] The inner ring 20b of the bearing 20 is fitted into the outer peripheral surface of the cylindrical portion 31. The external teeth 32 are disposed on the side of the outer peripheral surface of the cylindrical portion 31 opposite to the end plate portion 8 in the axial direction. The external teeth 32 are formed in the same axial direction.

[0054] The pitch circle diameter of the external gear 32 is larger than the outer diameter of the cylindrical portion 31. The axial end of the inner ring 20b abuts against the stepped surface 32a of the external gear 32. Thus, the central gear 30 is axially positioned relative to the base plate portion 7.

[0055] The outer teeth 32 of the central gear 30, positioned relative to the base plate portion 7, are housed in the central recess 9. In this state, the end face 30a of the central gear 30 on the side opposite to the end plate portion 8 is located on approximately the same plane as the first end face 7h of the base plate portion 7. That is, the axial length of the outer teeth 32 is approximately the same as the depth of the central recess 9.

[0056] <Endplate Section>

[0057] The end plate portion 8 is formed in the shape of a circular plate. An end plate shaft insertion hole 8d is formed through the radial center of the end plate portion 8. The end plate shaft insertion hole 8d and the substrate shaft insertion hole 7d are arranged coaxially.

[0058] A plurality of crankshaft insertion holes 8j are formed around the end plate shaft insertion hole 8d of the end plate portion 8. Each crankshaft insertion hole 8j is arranged at equal intervals in the circumferential direction. Each crankshaft insertion hole 8j is arranged coaxially with the crankshaft insertion hole 7g of the base plate portion 7. That is, the central axis A2 of the crankshaft insertion holes 8j and crankshaft insertion holes 7g that are opposite each other in the axial direction is parallel to the first rotation axis A1.

[0059] In the end plate portion 8, a plurality of (e.g., two) bolt insertion holes 34 and end plate pin holes 35 are formed at locations along the axial direction opposite to the column portion 11 of the base plate portion 7. Each bolt insertion hole 34 is coaxially disposed with the internal thread portion 26 of the column portion 11. The end plate pin hole 35 is coaxially disposed with the column pin hole 27.

[0060] Bolts 91 are inserted into bolt insertion holes 34 from the side opposite to the base plate 7, and bolts 91 are fastened to the internal thread portion 26. Pins 92 are inserted into or pressed into end plate pin holes 35 and pin holes 27. Thus, based on the accurate positioning between the base plate 7 and the end plate 8, the end plate 8 is fixed to the base plate 7.

[0061] <Speed ​​Reduction Mechanism>

[0062] The reduction mechanism 4 reduces the rotation of the electric motor (not shown) at a certain rate, thereby causing the gear carrier 3 to rotate. The reduction mechanism 4 has the following main components: a central gear 30, which is rotatably supported on the base plate 7; three crankshafts (an example of the second shaft in the claim) 13, which are respectively inserted into the crankshaft insertion hole 7g of the base plate 7 and the crankshaft insertion hole 8j of the end plate 8; a transmission spur gear 14, which is provided on each crankshaft 13; an intermediate spur gear (an example of the second gear in the claim) 50, which is provided on one of the three crankshafts 13; and two external gears 15 and 16 (first external gear 15 and second external gear 16), which are provided between the base plate 7 and the end plate 8.

[0063] Figure 3 yes Figure 1 Enlarged view of Part III.

[0064] like Figures 1-3 As shown, the crankshaft 13 is rotatably supported on the base plate 7 and the end plate 8 by means of crankshaft bearings 18 respectively provided in the crankshaft insertion holes 7g in the base plate 7 and the crankshaft insertion holes 8j in the end plate 8. The crankshaft bearings 18 are, for example, cylindrical roller bearings. However, it is not limited to this and various types of bearings can be used.

[0065] The crankshaft 13 includes: a shaft body 13a that rotates about a central axis A2; a support shaft 13d disposed at the end of the shaft body 13a on the side near the base plate portion 7; and a first eccentric portion 13b and a second eccentric portion 13c formed at the center of the axial direction of the shaft body 13a. Hereinafter, the central axis A2 will be referred to as the second rotation axis A2 of the crankshaft 13. The two axial sides of the shaft body 13a are rotatably supported on the gear carrier 3 (base plate portion 7 and end plate portion 8) by means of crankshaft bearings 18.

[0066] The first eccentric portion 13b and the second eccentric portion 13c are eccentric relative to the second rotation axis A2. The first eccentric portion 13b and the second eccentric portion 13c are arranged axially adjacent between the two crankshaft bearings 18. In other words, the first eccentric portion 13b and the second eccentric portion 13c are arranged axially adjacent between the base plate portion 7 and the end plate portion 8. The first eccentric portion 13b and the second eccentric portion 13c are arranged with a phase angle offset of 180°.

[0067] At each eccentric portion 13b, 13c, the first external gear 15 and the second external gear 16 are rotatably supported on each crankshaft 13 by means of a sway bearing 19. The sway bearing 19 is, for example, a cylindrical roller bearing. However, it is not limited to this and various types of bearings can be used.

[0068] The first external gear 15 and the second external gear 16 are disposed between the base plate portion 7 and the end plate portion 8. The first external gear 15 and the second external gear 16 overlap in the axial direction. Through holes 15a and 16a are formed in the first external gear 15 and the second external gear 16. The outer peripheral surface of the swing bearing 19 is engaged with each through hole 15a and 16a. Thus, if the first eccentric portion 13b and the second eccentric portion 13c swing and rotate due to the rotation of the crankshaft 13, the first external gear 15 and the second external gear 16 swing and rotate by means of the swing bearing 19.

[0069] Openings 15b and 16b are formed on the first external gear 15 and the second external gear 16, respectively, to avoid interference with the column portion 11. Shaft insertion holes 15c and 16c are formed at the radial center of the first external gear 15 and the second external gear 16. External teeth 15d and 16d are formed on the outer periphery of the first external gear 15 and the second external gear 16, respectively. The number of teeth on each external tooth 15d and 16d is, for example, one less than the number of internal toothed pins 5 in the housing 2.

[0070] The transmission spur gear 14 is fitted and fixed to the support shaft 13d of each crankshaft 13. More specifically, a shaft-side spline 61 is formed on the outer peripheral surface of the support shaft 13d, extending from a position near the shaft body 13a to the top end 13e on the side opposite to the shaft body 13a. On the outer peripheral surface of the support shaft 13d, a first retaining ring 70a is installed on the shaft-side spline 61 on the shaft body 13a side, and a second retaining ring 70b is installed on the top end 13e side.

[0071] The transmission spur gear 14 is formed in the shape of a circular plate. A shaft insertion hole 14a is formed in the radial center of the transmission spur gear 14. A gear side spline 62 is formed in the shaft insertion hole 14a. By engaging these shaft side splines 61 and gear side splines 62, the transmission spur gear 14 and the support shaft 13d are engaged to prevent relative rotation. Teeth 14b are formed on the outer peripheral surface of the transmission spur gear 14.

[0072] The transmission spur gear 14 is positioned relative to the support shaft 13d by abutting against the first retaining ring 70a mounted on the support shaft 13d. The transmission spur gear 14, positioned relative to the support shaft 13d, is housed in the gear housing recess 10 of the base plate portion 7. In this state, the teeth 14b of the transmission spur gear 14 mesh with the external teeth 32 of the center gear 30.

[0073] An intermediate spur gear 50 and a transmission spur gear 14 are arranged axially on a support shaft 13d of one of the three crankshafts 13. More specifically, a bushing 63 is fitted into the support shaft 13d on the portion closer to the top 13e of the transmission spur gear 14. Bushing-side splines 64 are formed on the inner circumferential surface of the bushing 63. Through the engagement of these shaft-side splines 61 and bushing-side splines 64, the bushing 63 and the support shaft 13d are fitted together and cannot rotate relative to each other. The intermediate spur gear 50 is rotatably supported on the outer circumferential surface of the bushing 63 by means of a plurality of cylindrical rollers 65. Teeth 50a are formed on the outer circumferential surface of the intermediate spur gear 50.

[0074] On one side 50b of the intermediate spur gear 50 opposite to the transmission spur gear 14, a recess 51 is formed in the radial center. The recess 51 is circular in shape when viewed axially. A flat washer 52 that engages with the support shaft 13d is placed on the bottom surface 51a of the recess 51. The side 52a of the flat washer 52 opposite to the bottom surface 51a abuts against the second retaining ring 70b mounted on the support shaft 13d.

[0075] This prevents the intermediate spur gear 50 from detaching from the support shaft 13d and positions the intermediate spur gear 50 relative to the support shaft 13d. In this state, one side 50b of the intermediate spur gear 50 and the first end face 7h of the base plate portion 7 are located on approximately the same plane.

[0076] The pitch circle diameter of the tooth 50a in the intermediate spur gear 50 is the same as the pitch circle diameter of the tooth 14b in the transmission spur gear 14. Therefore, the tooth 50a of the intermediate spur gear 50 meshes with the external tooth 32 of the center gear 30 in the same way as the transmission spur gear 14.

[0077] Furthermore, the input gear 80, mounted on the motor shaft of an electric motor (not shown), meshes with the intermediate spur gear 50. The input gear 80 does not mesh with the transmission spur gear 14.

[0078] <Operation of the speed reduction device>

[0079] Next, the operation of the deceleration device 1 will be explained.

[0080] If the input gear 80 rotates due to the drive of an electric motor (not shown), the intermediate spur gear 50, which meshes with the input gear 80, will also rotate. The intermediate spur gear 50 is rotatably supported on the support shaft 13d. Therefore, the crankshaft 13 does not rotate, only the intermediate spur gear 50 rotates. If the intermediate spur gear 50 rotates, the center gear 30, which meshes with the intermediate spur gear 50, will also rotate.

[0081] As the central gear 30 rotates, the three transmission spur gears 14 meshing with the central gear 30 rotate simultaneously. The corresponding crankshaft 13 rotates integrally with these transmission spur gears 14.

[0082] Therefore, each external gear 15 and 16 oscillates and rotates. Here, the number of teeth on each external gear 15d and 16d is, for example, one less than the number of internal gear pins 5. Therefore, each external gear 15d and 16d deviates circumferentially from its meshing position with respect to the internal gear pins 5 (housing 2), and each external gear 15 and 16 rotates. Its rotation is decelerated relative to the rotation of the crankshaft 13.

[0083] As the external gears 15 and 16 rotate, each crankshaft 13 also rotates on its own axis about the second rotation axis A2 and revolves around the first rotation axis A1. Each crankshaft 13 is rotatably supported on the gear carrier 3 (base plate 7 and end plate 8). Therefore, the gear carrier 3 rotates along with the revolution of each crankshaft 13.

[0084] As the gear carrier 3 rotates, the reduction gear 1 slows down the rotation of the electric motor and outputs it to the driven member (not shown). This drives the driven member. Assuming the driven member is fixed, the reduction gear 1 can slow down the rotation of the electric motor and output it from the housing 2.

[0085] However, the driven member (not shown) fixed to the gear carrier 3 is secured by fastening a bolt (not shown) to a plurality of mounting internal threads 12 formed on the first end face 7h of the base plate portion 7. The plurality of mounting internal threads 12 are formed on the outer periphery of the first end face 7h of the base plate portion 7 and along the entire surface between the circumferentially adjacent gear receiving recesses 10.

[0086] Here, for example, the intermediate spur gear 50, which transmits the rotation of the input gear 80 to the central gear 30, is not arranged axially with the transmission spur gear 14, but is positioned at a different location from the location where the transmission spur gear 14 is arranged. In this case, the intermediate spur gear 50 is positioned between two circumferentially adjacent transmission spur gears 14. This correspondingly reduces the space in the first end face 7h of the base plate portion 7 for forming the mounting internal thread portion 12. Therefore, the fixing force between the gear carrier 3 and the driven member (not shown) is reduced.

[0087] Therefore, according to the above embodiment, a transmission spur gear 14 and an intermediate spur gear 50 are provided on a single crankshaft 13, thus saving space in terms of the space occupied by the transmission spur gear 14 and the intermediate spur gear 50 when viewed axially. Therefore, multiple mounting internal thread portions 12 can be formed on the entire surface of the first end face 7h of the base plate portion 7, near the outer periphery and adjacent to the circumferentially adjacent gear receiving recesses 10. Therefore, the gear carrier 3 and the driven member (not shown) can be securely fixed.

[0088] A transmission spur gear 14 and an intermediate spur gear 50 are provided on a single crankshaft 13, and the crankshaft 13 and the intermediate spur gear 50 are configured to rotate freely relative to each other. Therefore, power can be transmitted in the order of input gear 80, intermediate spur gear 50, center gear 30, and transmission spur gear 14. In this way, a reduction mechanism 4 with multiple transmission paths (intermediate spur gear 50, center gear 30, and transmission spur gear 14) can be arranged in a space-saving manner when viewed axially.

[0089] In an eccentric oscillating type speed reduction device such as speed reduction device 1, sufficient space can be ensured at the first end face 7h of the base plate 7 for fixing the driven member (not shown).

[0090] The intermediate spur gear 50 and the transmission spur gear 14 are arranged axially. Therefore, the transmission spur gear 14 and the intermediate spur gear 50 can be arranged in a concentrated manner. Accordingly, the space occupied by the transmission spur gear 14 and the intermediate spur gear 50 can be saved. Therefore, the reduction mechanism 4 can be arranged in a more space-saving manner.

[0091] [Variation Example]

[0092] In the above embodiment, the intermediate spur gear 50 is supported on the support shaft 13d in a manner that allows it to rotate freely relative to the support shaft 13d by means of a bushing 63 and a plurality of cylindrical rollers 65. The following situation was described: a shaft-side spline 61 is formed on the outer peripheral surface of the support shaft 13d, and a bushing-side spline 64 is formed on the inner peripheral surface of the bushing 63. Furthermore, the situation was described where the shaft-side spline 61 and the bushing-side spline 64 are fitted together so that they cannot rotate relative to each other. In other words, the situation was described where the support shaft 13d is splinedly fitted with the bushing 63. However, this is not a limitation; the intermediate spur gear 50 can simply be supported on the support shaft 13d in a manner that allows it to rotate freely relative to the support shaft 13d. More specifically, the following description will elaborate on this.

[0093] Figure 4 This is an enlarged cross-sectional view of the intermediate spur gear 50 and its surroundings in the first variant. Figure 4 With the aforementioned Figure 3 Correspondingly.

[0094] like Figure 4 As shown, in the first modified example, no shaft-side spline 61 is formed on the outer peripheral surface of the support shaft 13d at the location where the intermediate spur gear 50 is fitted. On the other hand, no bushing-side spline 64 is formed on the inner peripheral surface of the bushing 63. The bushing 63 is fitted only with the outer peripheral surface of the support shaft 13d by, for example, pressing.

[0095] Figure 5 This is an enlarged cross-sectional view of the intermediate spur gear 50 and its surroundings in the second variation. Figure 5 With the aforementioned Figure 3 Correspondingly.

[0096] like Figure 5 As shown, in the second modified example, the bushing 63 is not fitted onto the outer peripheral surface of the support shaft 13d. Multiple cylindrical rollers 65 are provided on the outer peripheral surface of the support shaft 13d. The intermediate spur gear 50 is directly supported on the support shaft 13d in a rotatable manner by means of the cylindrical rollers 65.

[0097] Figure 6This is an enlarged cross-sectional view of the intermediate spur gear 50 and its surroundings in the third variation. Figure 6 With the aforementioned Figure 3 Correspondingly.

[0098] like Figure 6 As shown, in the third variation, the intermediate spur gear 50 is rotatably supported on the support shaft 13d by means of a deep groove ball bearing 75.

[0099] In the third variation, a variety of bearings can be used to replace the deep groove ball bearing 75.

[0100] Furthermore, the present invention is not limited to the embodiments described above, but includes embodiments in which various modifications are made to the embodiments described above without departing from the spirit of the present invention.

[0101] For example, in the above embodiment, the reduction mechanism 4 constituting the eccentric oscillating type reduction device 1 was described as an example of a gear device. However, it is not limited to this, and the gear device may at least include the following components: two shafts arranged in parallel (e.g., a central gear 30 and a crankshaft 13); a gear (e.g., a transmission spur gear 14) integrally disposed on one of the two shafts and meshing with the gear (e.g., an external gear 32) of the other shaft; and a gear (e.g., an intermediate spur gear 50) rotatably disposed on one of the two shafts and meshing with the gear of the other shaft.

[0102] In the above embodiments, the reduction mechanism 4 was described with two external gears 15 and 16. The reduction mechanism 4 was also described with three crankshafts 13. However, it is not limited to this; the reduction mechanism 4 may have at least one external gear. The number of crankshafts 13 may also be multiple.

[0103] In the above embodiments, the case where each main bearing 41, 42 is, for example, a tapered roller bearing has been described. However, it is not limited to this, and various types of bearings can be used instead of tapered roller bearings as each main bearing 41, 42.

[0104] In the above embodiment, the intermediate spur gear 50 and the transmission spur gear 14 are arranged axially. However, this is not a limitation; the intermediate spur gear 50 may not be arranged axially with the transmission spur gear 14. The intermediate spur gear 50 may also be provided at the end of the crankshaft 13 opposite to the end where the transmission spur gear 14 is provided, that is, on the end plate portion 8 side. In this case, the end of the crankshaft 13 on the end plate portion 8 side can protrude axially outward through the end plate portion 8.

[0105] In the embodiments disclosed in this specification, a component composed of multiple objects can either be integrated into one object, or the component composed of a single object can be divided into multiple objects. Regardless of whether they are integrated or not, they can be configured in a manner that achieves the purpose of the invention.

Claims

1. A gear mechanism comprising: The first shaft has teeth at its end; The second axis is arranged parallel to the first axis; A first gear, integrally disposed at the end of the second shaft and meshing with the teeth of the second shaft; and The second gear is supported at the end of the second shaft in a manner that allows it to rotate freely relative to the second shaft, and meshes with the teeth.

2. The gear device according to claim 1, wherein, The gear device includes: An internal gear, which has internal teeth on its inner circumferential surface; A gear carrier is disposed radially inside the internal gear and is supported on the internal gear in a manner that allows it to rotate freely relative to the internal gear. A fixing part, which is arranged along the outer periphery of the gear carrier, is used to fix the gear carrier and other components; The first shaft is coaxially arranged with the gear carrier at its radial center and is supported on the gear carrier in a manner that allows it to rotate freely relative to the gear carrier. A plurality of the second shafts, which are rotatably supported on the gear carrier and arranged around the first shaft; and The external gear, housed in the gear carrier, meshes with the internal gear. The second axis has: Shaft body; and An eccentric portion is disposed on the shaft body and is eccentric relative to the axis of rotation of the shaft body. The external gear is rotatably supported on the eccentric part. The second gear is disposed on one of the plurality of the second shafts.

3. The gear device according to claim 1 or 2, wherein, The first gear and the second gear are arranged axially. The second gear is supported on the second shaft by means of a bearing.

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