Eccentric oscillation type gear device

Abstract

To provide an eccentric oscillation type gear device that can ensure smooth supply of a lubricant to pin holes.SOLUTION: An eccentric oscillation type gear device 100 comprises a first external gear 7 and a second external gear 8 to be oscillated by eccentric parts 24 and 25. The first external gear 7 and the second external gear 8 comprise pin holes 46 and 47 penetrated by a pin member 48 in an axial direction. A tooth surface 72 of the first external gear 7 comprises a guide part 5 for guiding a lubricant J toward the pin hole 47 of the second external gear 8.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an eccentric swing type gear device.

Background Art

[0002] A gear device having a plurality of external gear wheels that swing with different phases is known. For example, Patent Document 1 describes a differential reduction gear including an internal gear wheel, a plurality of external gear wheels that are internally meshed with the internal gear wheel, an input shaft provided with an eccentric portion, and a carrier member having a plurality of pins. The external gear wheels have a plurality of pin holes on concentric circles, and pins are loosely inserted into each pin hole. When the input shaft rotates, the eccentric portion swings the plurality of external gear wheels with different phases from each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor obtained the following new recognition regarding the eccentric swing type gear device. In order to improve the internal lubrication state, the device described in Patent Document 1 has a configuration in which at least a part of the pin holes of one external gear wheel protrudes radially outward from the tooth bottom surface of the other external gear wheel when viewed in the axial direction of the internal gear wheel. With this configuration, it becomes easier for the lubricant to flow from the tooth bottom surface of the external gear wheel toward the pin holes. However, this configuration has limitations from the viewpoint of making the supply of the lubricant to the pin holes smoother.

[0005] In view of such problems, one object of the present invention is to provide an eccentric swing type gear device capable of making the supply of the lubricant to the pin holes smoother.

Means for Solving the Problems

[0006] In order to solve the above problems, an eccentric swing type gear device according to an aspect of the present invention is an eccentric swing type gear device including a first external gear and a second external gear that are swung in an eccentric portion, wherein the first external gear and the second external gear have pin holes through which a pin member penetrates in the axial direction. The tooth surface of the first external gear has a guiding portion for guiding a lubricant toward the pin hole of the second external gear.

[0007] In addition, any combination of the above components, or those obtained by mutually substituting the components and expressions of the present invention among methods, systems, etc., are also effective as aspects of the present invention.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an eccentric swing type gear device capable of more smoothly supplying a lubricant to a pin hole.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to the accompanying drawings based on preferred embodiments. In the embodiments and modifications, the same or equivalent components and members are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Also, the dimensions of the members in each drawing are shown enlarged or reduced as appropriate for ease of understanding. Further, some of the members that are not important for explaining the embodiments in each drawing are omitted from the display.

[0011] Also, terms including ordinals such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from another, and the components are not limited by this term.

[0012] [Embodiment] With reference to FIGS. 1 and 2, the overall configuration of an eccentric swing type gear device 100 (hereinafter sometimes referred to as "gear device 100") according to an embodiment will be described. FIG. 1 is a cross-sectional side view showing an example of the gear device 100. FIG. 2 is a view showing the periphery of the pin holes 46 and 47 of the gear device 100, and shows an enlarged view of the range of the circle Q in FIG. 1.

[0013] The gear device 100 mainly includes a crankshaft 20, external gears 7 and 8, an internal gear 16, eccentric bearings 17 and 18, a carrier 35, an input-side carrier 36, a main bearing 37, crankshaft bearings 39 and 40, a pin member 48, casings 61 and 62, and an input-side cover 63. Hereinafter, the direction along the central axis line La of the internal gear 16 is referred to as the "axial direction", and the circumferential direction and the radial direction of a circle centered on the central axis line La are referred to as the "circumferential direction" and the "radial direction", respectively. Also, the side where the external gears 7 and 8 are provided with respect to the carrier 35 in the axial direction (the right side in the figure) is referred to as the input side, and the opposite side (the left side in the figure) is referred to as the anti-input side.

[0014] The gear device 100 has a speed reduction mechanism that reduces and outputs the rotation input to the crankshaft 20 from a power source such as a motor (not shown). There is no limitation on this speed reduction mechanism as long as it can reduce and output the input rotation, and various mechanisms can be used. The gear device 100 of the embodiment is an eccentric swing type gear device that causes the external gear to rotate by swinging the external gear that meshes with the internal gear, and outputs the generated rotation component from the carrier 35 or the casings 61, 62 to the driven member. The gear device 100 of the embodiment is of a center crank type in which the central axis of the crankshaft 20 is provided on the same axis as the central axis La of the internal gear.

[0015] The crankshaft 20 is a shaft body that extends from the input side to the anti-input side in the axial direction and is rotated around the rotation center line La by the input rotation. The crankshaft 20 in this example is a hollow shaft, but it may also be a solid shaft. On the outer periphery of the crankshaft 20, in order from the anti-input side to the input side, a first shaft portion 22, a first eccentric portion 24, a second eccentric portion 25, and a second shaft portion 26 are provided. When the first eccentric portion 24 and the second eccentric portion 25 are collectively referred to, they are called the eccentric portions 24, 25. The first shaft portion 22 and the second shaft portion 26 support the inner rings of the crankshaft bearings 39, 40. The first eccentric portion 24 and the second eccentric portion 25 are cylindrical portions having a larger diameter than the first shaft portion 22 and are eccentric as will be described later. The second shaft portion 26 is a cylindrical portion having the same diameter as the first shaft portion 22.

[0016] The first shaft portion 22 on the anti-input side of the crankshaft 20 is supported by the carrier 35 via the crankshaft bearing 39. The second shaft portion 26 on the input side of the crankshaft 20 is supported by the input side cover 63 via the second crankshaft bearing 40. That is, the crankshaft 20 is rotatably supported with respect to the carrier 35 and the input side cover 63. The input side cover 63 is disposed on the side portion on the input side of the external gears 7, 8. The input side cover 63 is connected to the input side of the casings 61, 62 described later using bolts B1 and covers the input side of the speed reduction mechanism.

[0017] The crankshaft bearing 39 is disposed between the carrier 35 and the shaft portion 22 of the crankshaft 20. The input side of the crankshaft bearing 40 is disposed between the input side cover 63 and the shaft portion 26 of the crankshaft 20, and the anti-input side of the crankshaft bearing 40 is disposed between the input side carrier 36 and the shaft portion 26 of the crankshaft 20. For the crankshaft bearings 39 and 40, various known bearing mechanisms can be adopted. In this example, the crankshaft bearings 39 and 40 are ball bearings having spherical rolling elements.

[0018] The crankshaft 20 is an eccentric shaft having a plurality of eccentric portions 24 and 25 for swinging the external gear wheels 7 and 8, and may be referred to as an input shaft. The axial centers of the eccentric portions 24 and 25 are eccentric with respect to the rotation center line of the crankshaft 20 (coincident with the central axis La). In the embodiment, two eccentric portions 24 and 25 are provided, and the eccentric phases of the adjacent eccentric portions 24 and 25 are shifted by 180°. Eccentric bearings 17 and 18 are disposed on the outer circumferences of the eccentric portions 24 and 25. The eccentric bearings 17 and 18 in this example are roller bearings having a plurality of cylindrical rolling elements.

[0019] The external gear wheels 7 and 8 include a first external gear wheel 7 and a second external gear wheel 8 disposed on the input side of the first external gear wheel 7. When distinguishing them, they are denoted as the first external gear wheel 7 and the second external gear wheel 8, and when not distinguishing them, they are denoted as the external gear wheels 7 and 8.

[0020] The external gear wheels 7 and 8 are swingably incorporated on the outer circumferences of the eccentric portions 24 and 25 via the eccentric bearings 17 and 18. The external gear wheels 7 and 8 are internally meshed with the internal gear wheel 16 while swinging respectively. Corrugated external teeth 71 and 81 are formed on the outer circumferences of the external gear wheels 7 and 8, and by the movement of these teeth while contacting the internal gear wheel 16, the external gear wheels 7 and 8 can swing in a plane with the central axis as the normal line.

[0021] In order to facilitate the supply of the lubricant J to the pin holes 46 and 47, in the embodiment, a part of the pin hole 47 of the second external gear 8 protrudes radially outward from the outer peripheral surface of the external teeth 71 of the first external gear 7. Further, the tooth surface 72 of the external teeth 71 faces axially a part of the pin hole 47. That is, the teeth of the first external gear 7 overlap axially at least a part of the pin hole 47 of the second external gear 8. Similarly, a part of the pin hole 46 of the first external gear 7 protrudes radially outward from the outer peripheral surface of the external teeth 81 of the second external gear 8. Further, the tooth surface 82 of the external teeth 81 faces axially a part of the pin hole 46. That is, the teeth of the second external gear 8 overlap axially at least a part of the pin hole 46 of the first external gear 7.

[0022] The input side carrier 36 is a hollow disk-shaped member surrounding the central axis La and is disposed between the second external gear 8 and the input side cover 63. The input side carrier 36 is fixed to the input side of the pin member 48 and restricts the axial movement of the second external gear 8. The second shaft portion 26 of the crankshaft 20 penetrates the input side carrier 36 via the crankshaft bearing 40. The input side carrier 36 is supported by the second shaft portion 26 so as to be rotatable with respect to the crankshaft 20.

[0023] The internal gear 16 meshes with the external gears 7 and 8. The internal gear 16 of the embodiment is composed of internal teeth integrally provided on the inner peripheral side of the second casing 62. The number of internal teeth of the internal gear 16 is slightly (by 2 in this example) more than the number of external teeth of the external gears 7 and 8.

[0024] The external gears 7 and 8 are formed with central holes 44 and 45 and a plurality of pin holes 46 and 47. The central holes 44 and 45 are axial through holes provided coaxially with the rotation centers of the external gears 7 and 8. The eccentric portions 24 and 25 penetrate the central holes 44 and 45 via the eccentric bearings 17 and 18. The plurality of pin holes 46 and 47 are axial through holes provided at positions offset from the rotation centers of the external gears 7 and 8 at predetermined intervals in the circumferential direction. The pin member 48 penetrates the pin holes 46 and 47.

[0025] As an example, the external gears 7 and 8 have a tooth profile with a small number of teeth of a trochoid tooth profile, where the number of teeth is approximately one times the module of the gear. The central hole 44 of the first external gear 7 and the pin hole 47 of the second external gear 8 communicate with each other when viewed axially. The central hole 45 of the second external gear 7 and the pin hole 46 of the first external gear 7 communicate with each other when viewed axially. The side surface 77 of the first external gear 7 and the side surface 87 of the second external gear 8 are arranged so as to slide relative to each other with a slight gap therebetween.

[0026] In the embodiment, in order to smoothly slide with the pin holes 46 and 47, a cylindrical inner roller 49 is disposed on the outer periphery of the pin member 48. Note that it is not essential to provide the inner roller 49, and the pin member 48 may be configured to directly slide with the pin holes 46 and 47 without using the inner roller 49. In the following description, an example in which the inner roller 49 slides with the pin holes 46 and 47 is shown. However, when the pin member 48 directly slides with the pin holes 46 and 47, the inner roller 49 shall be read as the pin member 48.

[0027] The outer diameter of the inner roller 49 is smaller than the inner diameter of the pin holes 46 and 47 by an amount equivalent to twice the eccentricity. A clearance serving as play for absorbing the rocking components of the external gears 7 and 8 is provided between the inner roller 49 and the pin member 48, and the pin member 48 is always in contact with a part of the pin holes 46 and 47 via the inner roller 49. The pin member 48 revolves around the axis of the crankshaft 20 in synchronization with the rotation components of the external gears 7 and 8, and rotates the carrier 35 around the axis of the crankshaft 20. The pin member 48 functions as an inner pin contributing to the transmission of power between the carrier 35 and the external gears 7 and 8. In this case, the pin holes 46 and 47 may be referred to as inner pin holes. Note that the pin member 48 may include a connecting pin that does not contribute to the transmission of power between the carrier 35 and the external gears 7 and 8.

[0028] The casings 61 and 62 have a cylindrical shape that constitutes the outer shell of the gear device 100. The casings 61 and 62 include a first casing 61 and a second casing 62 connected to the input side of the first casing 61. The first casing 61 mainly surrounds the main bearing 37 and the oil seal S1. An internal gear 16 is provided on the inner peripheral surface of the second casing 62. The first casing 61, the second casing 62, and the input side cover 63 are connected using bolts B1.

[0029] The carrier 35 has a hollow circular shape. The carrier 35 is disposed on the side of the outer gears 7 and 8 opposite to the input side. The carrier 35 is rotatably supported with respect to the casings 61 and 62 via the main bearing 37. The carrier 35 rotatably supports the anti-input side of the crankshaft 20 via the first crankshaft bearing 39. The input side cover 63 rotatably supports the input side of the crankshaft 20 via the second crankshaft bearing 40.

[0030] The main bearing 37 is disposed between the first casing 61 and the carrier 35. The main bearing 37 can adopt various known bearing mechanisms. In this example, the main bearing 37 is a cross roller bearing. The outer ring of the main bearing 37 is formed on the first casing 61 and does not have a dedicated outer ring. The inner ring of the main bearing 37 is formed on the carrier 35 and does not have a dedicated inner ring.

[0031] The pin members 48 are rod-shaped members extending axially from the input side of the carrier 35 toward the input side carrier 36, and a plurality of them are provided at predetermined intervals in the circumferential direction. The plurality of pin members 48 penetrate the pin holes 46 and 47 of the first outer gear 7 and the second outer gear 8. The anti-input side of the plurality of pin members 48 is integrated by the carrier 35. In this example, the plurality of pin members 48 are formed separately from the carrier 35 and connected to the carrier 35. Some or all of the plurality of pin members 48 may be formed integrally with the carrier 35 from a single-piece material. The input side of the plurality of pin members 48 is integrated by the input side carrier 36. The input side of the plurality of pin members 48 is fitted into holes provided in the input side carrier 36.

[0032] The deceleration operation of the gear device 100 will be described. When rotational power is transmitted to the crankshaft 20, the eccentric portions 24 and 25 rotate around the rotation center line passing through the crankshaft 20. When the eccentric portions 24 and 25 rotate, the external gear wheels 7 and 8 swing via the eccentric body bearings 17 and 18. When the external gear wheels 7 and 8 swing, the meshing positions of the internal teeth of the external gear wheels 7 and 8 and the internal gear 16 shift sequentially. As a result, every time the crankshaft 20 makes one rotation, rotation of one of the external gear wheels 7 and 8 and the internal gear 16 occurs by an amount corresponding to the difference between the number of teeth of the external gear wheels 7 and 8 and the number of teeth of the internal gear 16. In the embodiment, the external gear wheels 7 and 8 rotate, and decelerated rotation is output from the carrier 35. When the carrier 35 rotates, a driven member (not shown) connected to the carrier 35 is rotationally driven.

[0033] A lubricant J is enclosed inside the gear device 100, and the lubricant J is sealed by oil seals S1, S2, and S3. The oil seal S1 is disposed on the anti-input side of the main bearing 37, the oil seal S2 is disposed on the anti-input side of the crankshaft bearing 39, and the oil seal S3 is disposed on the input side of the crankshaft bearing 40.

[0034] Next, the lubrication of the pin holes 46 and 47 will be described. When the external gear wheels 7 and 8 rotate, the inner roller 49 contacts the inner peripheral surfaces of the pin holes 46 and 47. Therefore, it is important to supply the lubricant J to the pin holes 46 and 47 in order to ensure lubrication of these. In order to enhance the reliability of these contact portions, it is desirable to make the supply of the lubricant J to the pin holes 46 and 47 smoother, but the configuration described in Patent Document 1 has limitations from this viewpoint. Therefore, in the embodiment, the tooth surface 72 of the first external gear wheel 7 has a guiding portion 5 for guiding the lubricant J toward the pin hole 47 of the second external gear wheel 8.

[0035] Further, the tooth surface 82 of the second external gear 8 has another guiding portion 6 for guiding the lubricant J toward the pin hole 46 of the first external gear 7. Compared with a configuration without the guiding portion 6, the supply of the lubricant J to the pin hole 46 of the first external gear 7 can be made smoother. When the guiding portion 5 and the guiding portion 6 are collectively referred to, they are called guiding portions 5 and 6. The guiding portions 5 and 6 may be in any form as long as they can guide the lubricant J. Hereinafter, some examples of the guiding portion 5 will be described. The description of the guiding portion 5 is similarly applicable to the guiding portion 6.

[0036] With reference to FIGS. 3 to 5, the first to third examples of the guiding portion 5 will be described. FIG. 3 shows the first example of the guiding portion 5, FIG. 4 shows the second example of the guiding portion 5, and FIG. 5 shows the third example of the guiding portion 5. In FIGS. 3 to 5, (i) are the arrow views A, B, and C, (ii) is a partial front view of the first external gear 7, and (iii) are enlarged views of the circles E, F, and G.

[0037] The tooth surface 72 of the first external gear 7 has a tooth root 75, a tooth tip 76, and a region therebetween. As an example, the guiding portion 5 is provided in a tooth root region 73 of the tooth surface 72 that does not contact the internal gear 16. The tooth root region 73 is a region including the tooth root 75 and is a region that does not contact the internal gear 16 when meshing with the internal gear 16. By providing the guiding portion 5 in the tooth root region 73, wear of the guiding portion 5 can be suppressed when meshing with the internal gear 16. Note that the guiding portion 5 may be provided in a contact region of the tooth surface 72 that contacts the internal gear 16.

[0038] As an example, the guiding portion 5 has at least one of a parallel groove 52 parallel to the axial direction and an inclined groove 53 inclined with respect to the axial direction. The shapes of the parallel groove 52 and the inclined groove 53 can be set by experiments or simulations so as to obtain a desired lubricant guiding effect. By having the inclined groove 53 or the inclined groove 53, these grooves function as a space for collecting the lubricant J and also function as a flow path for the lubricant J toward the pin hole 47 of the second external gear 8.

[0039] In the first example shown in FIG. 3, the guiding portion 5 has inclined grooves 53 that are inclined with respect to the axial direction. In this example, the inclined grooves 53 inclined at 45° with respect to the axial direction are arranged in two groups in the circumferential direction with the bottom of the tooth 75 interposed therebetween. Each group has four inclined grooves 53. The two groups of inclined grooves 53 are configured to be line-symmetrical with respect to the bottom of the tooth 75. One group of the two groups of inclined grooves 53 and the other group of inclined grooves 53 are inclined so as to approach the bottom of the tooth 75 in the axial direction toward the pin hole 47 of the second external gear 8. The inclined grooves 53 of one group and the inclined grooves 53 of the other group are inclined such that the distance therebetween gradually decreases in the axial direction toward the pin hole 47 of the second external gear 8.

[0040] In the second example shown in FIG. 4, the guiding portion 5 has parallel grooves 52 parallel to the axial direction. In this example, three parallel grooves 52 are arranged spaced apart from each other in the circumferential direction, and the middle parallel groove 52 extends along the bottom of the tooth 75. The three parallel grooves 52 may be arranged at equal intervals or at unequal intervals. Each parallel groove 52 extends uniformly in the axial direction from one end to the other end of the tooth surface 72.

[0041] In the third example shown in FIG. 5, the guiding portion 5 has parallel grooves 52 parallel to the axial direction and inclined grooves 53 inclined with respect to the axial direction. In this example, the inclined grooves 53 inclined at 45° with respect to the axial direction are arranged in two groups in the circumferential direction with the bottom of the tooth 75 interposed therebetween, and one parallel groove 52 extends along the bottom of the tooth 75. The inclined grooves 53 in the third example are the same as the inclined grooves 53 in the first example. The parallel groove 52 in the third example is the same as the middle parallel groove 52 in the second example.

[0042] A fourth example of the guiding portion 5 will be described with reference to FIG. 6. FIG. 6 is a diagram showing the fourth example of the guiding portion 5. In FIG. 6, (i) is a partial front view of the first external gear 7, and (ii) is a side cross-sectional view of the first external gear 7. In the fourth example, the guiding portion 5 is provided in the bottom region 73 of the tooth and has a tapered portion 55 that tapers toward the second external gear 8 side (right side in the side cross-sectional view). The tapered portion 55 extends in the axial direction from one end to the other end of the tooth surface 72. The shape of the tapered portion 55 can be set by experiments or simulations so as to obtain a desired lubricant guiding effect.

[0043] The features of the gear device 100 of the embodiment will be described. The gear device 100 of the embodiment is an eccentric swing type gear device including a first external gear 7 and a second external gear 8 that are swung by eccentric portions 24 and 25. The first external gear 7 and the second external gear 8 have pin holes 46 and 47 through which a pin member 48 penetrates in the axial direction. On the tooth surface 72 of the first external gear 7, there is a guiding portion 5 that guides the lubricant J toward the pin hole 47 of the second external gear 8.

[0044] According to this configuration, since the lubricant J is guided to the pin hole 47 by the guiding portion 5, it becomes possible to supply the lubricant J to the pin hole 47 more smoothly. As a result, lubrication of the contact portion between the inner peripheral surface of the pin hole 47 and the inner roller 49 can be ensured, and the reliability of this contact portion can be enhanced.

[0045] According to the inventor's simulation, in the lubricant guiding effect, the first example is more preferable than the second example, the fourth example is more preferable than the first example, and the third example is more preferable than the fourth example. Also, a configuration in which the tapered portion 55 of the fourth example is combined with the third example is more preferable than the third example in the lubricant guiding effect. Further, according to the inventor's simulation, in the workability of the guiding portion 5 leading to the productivity of the gear device 100, the first example is more preferable than the fourth example, and the second example is more preferable than the first example.

[0046] The present invention has been described based on the embodiments. These embodiments are illustrative, and it is understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and such modified examples and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0047] (Modification example) Hereinafter, a modification example will be described. In the drawings and descriptions of the modification example, the same reference numerals are given to the components and members that are the same as or equivalent to those in the embodiment. Descriptions overlapping with the embodiment will be omitted as appropriate, and the configurations different from the embodiment will be mainly described.

[0048] In the description of the embodiment, an example in which the guiding portions 5 are provided on both of the external gear wheels 7 and 8 has been shown, but the present invention is not limited thereto. For example, a guiding portion may be provided on one of the two external gear wheels, and the other may not be provided with a guiding portion.

[0049] In the description of the embodiment, an example in which the extending end of the inclined groove 53 does not contact the axial end portion of the tooth surface 72 has been shown, but the present invention is not limited thereto. The extending end of the inclined groove may contact the axial end portion of the tooth surface, or may extend from one end to the other end of the tooth surface.

[0050] In the description of the embodiment, an example in which the gear device 100 includes only the external gear wheels 7 and 8 as external gear wheels has been shown, but the present invention is not limited thereto. For example, the gear device may include three or more external gear wheels. In this case, the guiding portion on the tooth surface of the intermediate external gear wheel sandwiched between the two external gear wheels on both sides may be configured to guide the lubricant toward the inner pin holes of the external gear wheels on both sides. For example, the guiding portion of the intermediate external gear wheel may include two groups of grooves that are inclined in opposite directions with respect to the axial direction. These two groups of grooves may be arranged on both sides from the axial center of the tooth surface.

[0051] In the description of the embodiment, an example in which the internal gear wheel 16 is composed of internal teeth integrally formed on the inner circumference of the casing has been shown, but the present invention is not limited thereto. For example, the internal gear wheel may be composed of a columnar pin member that is rotatably supported by a pin groove provided on the inner circumference of the casing.

[0052] In the description of the embodiment, an example in which the main bearing 37 is a cross roller bearing has been shown, but the present invention is not limited thereto. The main bearing may be a bearing of a type different from the cross roller bearing, such as an angular ball bearing or an angular roller bearing.

[0053] In the description of the embodiment, an example in which the crankshaft bearings 39 and 40 are ball bearings has been shown, but the present invention is not limited thereto. The crankshaft bearings may be bearings of a type different from the ball bearings, such as roller bearings.

[0054] In the description of the embodiment, an example in which the gear device 100 is a so-called center crank type eccentric swing type gear device has been shown, but the present invention is not limited to this. For example, the gear device may be a so-called distribution type eccentric swing type gear device in which a plurality of crank shafts are provided at positions offset from the central axis of the internal gear.

[0055] In the description of the embodiment, an example in which the external gears 7 and 8 have trochoidal teeth has been shown, but the present invention is not limited to this. The teeth of the external gear may have any tooth profile.

[0056] Each of these modifications has the same operations and effects as the embodiment.

[0057] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment produced by the combination has the effects of the combined embodiments and modifications.

Description of Reference Numerals

[0058] 5, 6 Induction part, 7 First external gear, 8 Second external gear, 16 Internal gear, 35 Carrier, 46, 47 Pin hole, 48 Pin member, 49 Inner roller, 52 Parallel groove, 53 Inclined groove, 55 Taper part, 71 External tooth, 72 Tooth surface, 73 Tooth bottom region, 75 Tooth bottom, 100 Eccentric swing type gear device.

Claims

**Claim 1** An eccentric swing type gear device including a first external gear and a second external gear that are swung by an eccentric portion, wherein the first external gear and the second external gear have pin holes through which a pin member penetrates in the axial direction, and the tooth surface of the first external gear has a guiding portion for guiding a lubricant toward the pin hole of the second external gear. An eccentric swing type gear device. **Claim 2** The eccentric swing type gear device according to claim 1, wherein at least a part of the pin hole of the second external gear overlaps the teeth of the first external gear in the axial direction. **Claim 3** including an internal gear meshing with the first external gear, wherein the guiding portion is provided in a tooth root region of the tooth surface that does not contact the internal gear. The eccentric swing type gear device according to claim 1. **Claim 4** The eccentric swing type gear device according to claim 3, wherein the guiding portion is provided in the tooth root region and includes a tapered portion that tapers toward the second external gear side. **Claim 5** The eccentric swing type gear device according to claim 1, wherein the guiding portion has at least one groove parallel to the axial direction and a groove inclined with respect to the axial direction. **Claim 6** The eccentric swing type gear device according to claim 1, wherein the tooth surface of the second external gear has another guiding portion for guiding a lubricant toward the pin hole of the first external gear.

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