Eccentric rocking type gear device

Abstract

To provide an eccentric rocking type gear device having a hollow part that can be enlarged.SOLUTION: An eccentric rocking type gear device 100 includes: an internal gear 16; an external gear 14; an eccentric body to oscillate the external gear 14; a carrier arranged on a side in an axial direction of the external gear 14; and plural inner pins 32 connected to the carrier at a position offset from the center of the carrier and passing through the external gear. A ratio between a pitch circle diameter Dp of the inner pins 32 and a tooth tip diameter De of the external gear 14 (pitch circle diameter Dp / tooth tip diameter De) is 0.77 to 0.85, a ratio between a diameter Dq of the inner pin 32 and the tooth tip diameter De of the external gear 14 (inner pin diameter Dq / tooth tip diameter De) is 0.06 to 0.10, and an inner pin occupancy that is a ratio of the inner pin 32 in a pitch circle of the inner pin 32 is at or larger than 0.25.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an eccentric oscillating gear device. [Background technology]

[0002] An eccentric oscillating reducer that reduces the speed of rotation input to an input shaft is known. In Patent Document 1, the present applicant disclosed an eccentric oscillating reducer that includes an external gear that oscillates as the input shaft rotates, and an internal gear with which the external gear internally meshes. The input shaft is a hollow shaft with a large diameter hollow portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-124730 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a reducer, electrical cables, pipes for sending air, and the like (hereinafter referred to as "wiring") are passed through the hollow portion. It is desirable for the hollow portion to be large so that the wiring can pass through with sufficient clearance. However, if the hollow portion is enlarged while keeping the outer diameter of the reducer constant, the strength of the reducer may decrease.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide an eccentric oscillating gear device in which the hollow portion can be enlarged. [Means for solving the problem]

[0006] In order to solve the above problems, an eccentric oscillating gear device of one embodiment of the present invention is an eccentric oscillating gear device comprising an internal gear, an external gear, an eccentric body that oscillates the external gear, a carrier arranged on the axial side of the external gear, and a plurality of inner pins that are connected to the carrier at a position offset from the center of the carrier and pass through the external gear, wherein the ratio of the pitch circle diameter of the inner pin to the tooth tip diameter of the external gear (pitch circle diameter / tooth tip diameter) is 0.77 to 0.85, the ratio of the diameter of the inner pin to the tooth tip diameter of the external gear (inner pin diameter / tooth tip diameter) is 0.06 to 0.10, and the inner pin occupancy rate, which is the proportion of the inner pin to the pitch circumference of the inner pin, is 0.25 or more.

[0007] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0008] According to the present invention, it is possible to provide an eccentric oscillating gear device capable of expanding the hollow portion. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side cross-sectional view showing an eccentric oscillating gear device according to an embodiment. [Diagram 2] 2 is a cross-sectional view of the eccentric oscillating gear device of FIG. 1 taken along line AA. [Diagram 3] FIG. 2 is an enlarged view of the external gear of the eccentric oscillating gear device of FIG. [Figure 4] FIG. 2 is a diagram for explaining dimensions of each part of the eccentric oscillating gear device of FIG. 1. [Diagram 5] FIG. 2 is a first diagram showing stress characteristics of members of the eccentric oscillating gear device of FIG. [Figure 6] FIG. 2 is a second diagram showing stress characteristics of the members of the eccentric oscillating gear device of FIG. [Figure 7] FIG. 4 is a third diagram showing stress characteristics of the members of the eccentric oscillating gear device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modified examples, the same or equivalent components and members are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0011] In addition, terms including ordinal numbers such as first, second, etc. are used to describe various components, but these terms are used only for the purpose of distinguishing one component from another component, and the components are not limited by these terms.

[0012] [Embodiment] The configuration of an eccentric oscillating gear device 100 according to an embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a side cross-sectional view that shows a schematic view of the eccentric oscillating gear device 100 of this embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. There is no limitation on the use of the eccentric oscillating gear device 100, but the eccentric oscillating gear device 100 of this example can be used in the joints of a multi-joint robot.

[0013] The following describes the overall configuration of the eccentric oscillating gear device 100. The eccentric oscillating gear device 100 mainly includes an input shaft 12, an external gear 14, an internal gear 16, carriers 18, 20, a casing 22, main bearings 24, 26, an eccentric bearing 30, an inner pin 32, and input shaft bearings 33, 34.

[0014] Hereinafter, the direction along the central axis La of the internal gear 16 will be referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the central axis La will be referred to as the "circumferential direction" and the "radial direction," respectively. Also, hereinafter, for convenience, one side in the axial direction (the right side in the figure) will be referred to as the input side, and the other side (the left side in the figure) will be referred to as the anti-input side. These directional notations do not limit the usage orientation of the eccentric oscillating gear device 100, and the eccentric oscillating gear device 100 can be used in any orientation.

[0015] The carriers 18, 20 include a first carrier 18 arranged on the non-input side of the external gear 14 and a second carrier 20 arranged on the input side of the external gear 14. The main bearings 24, 26 include a first main bearing 24 arranged on the non-input side of the external gear 14 and a second main bearing 26 arranged on the input side of the external gear 14. The input shaft bearings 33, 34 include a first input shaft bearing 33 arranged on the non-input side of the external gear 14 and a second input shaft bearing 34 arranged on the input side of the external gear 14.

[0016] The eccentric oscillating gear device 100 of this embodiment is a center crank type in which the input shaft (eccentric body shaft) 12 is arranged coaxially with the central axis La of the internal gear 16. The eccentric oscillating gear device 100 has a hollow portion H that penetrates the center in the axial direction. The hollow portion H is provided on the input shaft 12.

[0017] The casing 22 constitutes the outer shell of the eccentric oscillating gear device 100. The carriers 18, 20 are disposed inside the casing 22 and rotate relative to the casing 22. The input shaft 12 has a hollow cylindrical shape with a hollow portion H at its center. For example, a power transmission member such as a gear or pulley is connected to the input side end of the input shaft 12 by a connector such as a bolt, and the rotation of a motor disposed offset from the hollow portion H is transmitted.

[0018] The input shaft 12 has a plurality of eccentric portions 12a and functions as an eccentric body that oscillates the external gear 14. In this example, the input shaft 12 has two eccentric portions 12a that are 180° out of phase with each other. Both ends of the input shaft 12 are supported by carriers 18 and 20 via input shaft bearings 33 and 34. The number of eccentric portions 12a is not limited to two, and may be one or three or more.

[0019] There are no limitations on the configuration of the input shaft bearings 33, 34, but the rolling elements of the first input shaft bearing 33 in this example are balls (spherical bodies), and the rolling elements of the second input shaft bearing 34 are rollers (cylindrical bodies).

[0020] The external gear 14 is rotatably supported by the corresponding eccentric portion 12a via the eccentric bearing 30. The external gear 14 is formed with a center hole 14c and multiple inner pin holes 14h. The center hole 14c is a through hole provided at the center of the external gear 14. The multiple inner pin holes 14h are through holes provided on the same circumference (on the pitch circle) at positions offset from the center of the external gear 14. In the example of FIG. 2, ten inner pin holes 14h are arranged at intervals of 36° in the circumferential direction. An inner pin 32 is inserted into the inner pin hole 14h. The teeth formed on the outer periphery of the external gear 14 rotate while meshing with the teeth of the internal gear 16, causing the external gear 14 to oscillate.

[0021] The internal gear 16 meshes with the external gear 14. In this embodiment, the internal gear 16 is composed of an internal gear main body integrated with the casing 22, and an outer pin 16p (pin member) rotatably supported by this internal gear main body. The outer pin 16p forms the internal teeth of the internal gear 16. The number of internal teeth of the internal gear 16 (the number of outer pins 16p) is slightly more than the number of external teeth of the external gear 14 (by one in this example).

[0022] The first carrier 18 and the second carrier 20 are rotatably supported in the casing 22 via main bearings 24 and 26. The first carrier 18 supports the input shaft 12 via a first input shaft bearing 33. The second carrier 20 supports the input shaft 12 via a second input shaft bearing 34.

[0023] The first carrier 18 and the second carrier 20 are connected via an inner pin 32. The inner pin 32 axially passes through an inner pin hole 14h of the external gear 14 at a position radially offset from the axis of the external gear 14.

[0024] One of the carriers 18, 20 and the casing 22 functions as an output member that outputs rotational power to a reduced speed device, and the other functions as a fixed member that is fixed to an external member for supporting the eccentric oscillating gear device 100. In this embodiment, the output member is the first carrier 18 and the second carrier 20, and the fixed member is the casing 22.

[0025] In this example, ten inner pins 32 are arranged at intervals of 36° in the circumferential direction on the same circumference (pitch circle) offset from the center (axis) of the first carrier 18. FIG. 1 shows one inner pin 32. The inner pin 32 has a non-input side fixed (connected) to the first carrier 18 and an input side fixed (connected) to the second carrier 20. The inner pin 32 connects the first carrier 18 and the second carrier 20. In the example of FIG. 2, the inner pin 32 is formed integrally with the first carrier 18, and the input side is fixed to the second carrier 20 by a bolt B2. A sleeve 32s is provided on the outer periphery of the inner pin 32. The inner pin 32 is inserted into the inner pin hole 14h with a gap therebetween. The inner pin 32 abuts against a part of the inner pin hole 14h via the sleeve 32s. The inner pin 32 restricts the rotation of the external gear 14 and allows only its oscillation.

[0026] The main bearings 24, 26 are disposed between the first carrier 18 and the casing 22 and between the second carrier 20 and the casing 22. There are no limitations on the configuration of the main bearings 24, 26, but the main bearings 24, 26 in this example are angular contact ball bearings in which the rolling elements are spheres. The outer rings of the main bearings 24, 26 are supported by the casing 22. The inner ring of the first main bearing 24 is formed integrally with the carrier 18. The inner ring of the second main bearing 26 is formed integrally with the carrier 20.

[0027] The casing 22 is a hollow cylindrical member that surrounds the carriers 18, 20. The casing 22 has a large diameter portion 22f that protrudes radially outward. The large diameter portion 22f is provided with a bolt hole 22h that penetrates in the axial direction. The large diameter portion 22f is connected to an external mating member 50.

[0028] An oil seal 28 that seals out the lubricant from the main bearing 24 is provided between the casing 22 and the first carrier 18 .

[0029] The characteristic configuration of this embodiment will be described below.

[0030] The present inventors have studied eccentric oscillating gear devices and have obtained the following findings. Eccentric oscillating gear devices are used in a variety of applications, such as industrial robots and machine tools. Electrical cables and other wiring are passed through the hollow portion of the eccentric oscillating gear device. If the gap between this wiring and the hollow portion is small, they may interfere with each other, causing stress on the wiring and resulting in damage. Therefore, from the viewpoint of allowing the wiring to pass through with ease, it is desirable for the diameter of the hollow portion to be large.

[0031] The load applied to a gear device is large in a large gear device and small in a small gear device. Therefore, the hollow portion diameter can be generalized in relation to the size of the gear device. From the viewpoint of reducing the influence of variations in the casing shape, in this specification, the diameter of the hollow portion is generalized by the ratio (hollow portion diameter / tooth tip diameter) to the diameter of a circle passing through each tooth tip of the external gear (hereinafter referred to as "tooth tip diameter"). Hereinafter, this diameter ratio may be referred to as the hollow portion diameter ratio.

[0032] The stress at each part of the eccentric oscillating gear device 100 due to the load will be described with reference to Figures 3 and 4. Figure 3 is an enlarged view of a part of the external gear 14. Figure 4 is an explanatory diagram explaining the dimensions of each part. Figure 4 shows the hollow portion diameter Dh, the tooth tip diameter De, and the pitch circle diameter Dp. The tooth tip diameter De is the diameter of a circle that passes through each tooth tip 14e. The pitch circle diameter Dp is the diameter of the pitch circle 32d that passes through the center of each inner pin 32 (pitch circle diameter: PCD).

[0033] The inventors of the present invention conducted repeated experiments and simulations on the eccentric oscillating gear device 100 of this embodiment from the viewpoint of enlarging the hollow portion diameter Dh, and investigated the effects of changing the dimensions of each portion. As a result, they found that the stresses of the inner pin 32, the portion 14j between the tooth bottom 14b of the external gear 14 and the inner pin hole 14h, and the portion 14k between the center hole 14c and the inner pin hole 14h are important. In other words, they found that a life strength sufficient for practical use can be achieved by ensuring that the stresses of these portions satisfy the stress standards determined by market demands in normal applications of eccentric oscillating gear devices, such as industrial robots and machine tools.

[0034] First, the effects of changing the dimensions of each part will be described. When the hollow part diameter Dh is enlarged, the thickness of the part 14k between the center hole 14c of the external gear 14 and the inner pin hole 14h becomes thinner, so it is advantageous for the pitch circle diameter Dp of the inner pin 32 (which can also be called the pitch circle diameter of the inner pin hole 14h) to be larger. On the other hand, if the pitch circle diameter Dp is too large, the thickness of the part 14j between the tooth bottom 14b of the external gear 14 and the inner pin hole 14h becomes thinner, and there is a risk that the desired strength cannot be satisfied.

[0035] In addition, in order to increase the hollow portion diameter Dh while ensuring the thickness of the portion 14k and the portion 14j, it is advantageous to have a small inner pin hole diameter Dr. On the other hand, if the inner pin hole diameter Dr is made small, the inner pin diameter Dq will also be made small, and in this case, there is a risk that the strength of the inner pin will not be sufficient.

[0036] In order to satisfy the strength requirement while minimizing the inner pin diameter Dq, it is possible to increase the number of inner pins to distribute the load applied to each inner pin. The inner pin occupancy rate Eq may be increased to increase the overall strength of the multiple inner pins. However, if the inner pin occupancy rate Eq is increased too much, the spacing between the inner pins becomes small, making forging difficult, and manufacturing problems such as interference of the tool with the inner pin during processing may occur. The inner pin occupancy rate Eq is the ratio of the inner pin 32 to the circumference of the pitch circle 14d of the inner pin 32.

[0037] The inventors of the present invention came up with the idea that in order to increase the hollow portion diameter Dh while satisfying the stress standard, it is important to find appropriate ranges for the pitch circle diameter Dp, the inner pin diameter Dq, and the inner pin occupancy Eq of the inner pin 32. In the present invention, it can be said that the fact that this idea has been reached is itself extremely important.

[0038] 5 to 7, the relationship between the pitch circle diameter Dp, inner pin diameter Dq, and inner pin occupancy rate Eq of the inner pin 32 and the stress at each portion will be described. The pitch circle diameter Dp and inner pin diameter Dq can be generalized in relation to the size of the gear device. Hereinafter, the pitch circle diameter Dp and inner pin diameter Dq will be treated as ratios to the tooth tip diameter De of the external gear 14.

[0039] In Figs. 5 to 7, the vertical axis indicates the stress of each part. In these figures, (a) indicates the stress of the inner pin 32, (b) indicates the stress of the part 14j between the tooth bottom 14b and the inner pin hole 14h of the external gear 14, and (c) indicates the stress characteristic line of the part 14k between the center hole 14c and the inner pin hole 14h. These stresses are the stresses that occur in each part when a predetermined test load is applied to the gear device. The predetermined test load is a load that is set to simulate the load resistance required in the market for the gear device. In addition, "standard" indicates the standard level (upper limit level) of stress determined by market requirements. In these figures, the value of the horizontal axis at the intersection of the stress characteristic line and the standard line is the lower limit or upper limit of the standard range of stress (hereinafter simply referred to as "lower limit" or "upper limit"). In other words, when the value of the horizontal axis is within the range from the lower limit to the upper limit, it can be said that the stress is within the standard.

[0040] 5 shows the change in stress in the inner pin 32, the portion 14j, and the portion 14k when the ratio of the pitch circle diameter Dp to the tooth tip diameter De (pitch circle diameter Dp / tooth tip diameter De) is changed. The horizontal axis of this figure is the ratio of the pitch circle diameter Dp to the tooth tip diameter De.

[0041] As shown in Figure 5, as the pitch circle diameter Dp increases, the stress in the inner pin 32 and the portion 14k decreases, and the stress in the portion 14j increases. From this figure, when the ratio of the pitch circle diameter Dp to the tooth tip diameter De is in the range of 0.77 to 0.85, the stresses in the inner pin 32, the portion 14j, and the portion 14k are all within the standard range. The lower limit of the portion 14k is 0.77, which is larger than the lower limit of the inner pin 32, and the slope of the stress characteristic line is also large, so it is the lower limit of the entire range. The upper limit of the portion 14j is 0.85, which is the upper limit of the entire range.

[0042] FIG. 6 shows the change in stress of the inner pin 32, the portion 14j, and the portion 14k when the ratio of the inner pin diameter Dq to the tooth tip diameter De (inner pin diameter Dq / tooth tip diameter De) is changed. As shown in FIG. 6, as the inner pin diameter Dq increases, the stress of the inner pin 32 decreases, and the stress of the portion 14j and the portion 14k increases. From this figure, when the ratio of the inner pin diameter Dq to the tooth tip diameter De is in the range of 0.06 to 0.10, the stress of the inner pin 32, the portion 14j, and the portion 14k are all within the standard. The lower limit of the inner pin 32 is 0.06, which is the lower limit of the entire range. The upper limit of the portion 14j is 0.10, which is smaller than the upper limit of the portion 14k, and the slope of the stress characteristic line is also large, so it is the upper limit of the entire range.

[0043] FIG. 7 shows the change in stress of the inner pin 32, the portion 14j, and the portion 14k when the inner pin occupancy rate Eq is changed. As shown in FIG. 6, as the inner pin occupancy rate Eq increases, the stress of the inner pin 32, the portion 14j, and the portion 14k decreases. From this figure, when the inner pin occupancy rate Eq is in the range of 0.25 or more, the stress of the inner pin 32, the portion 14j, and the portion 14k is all within the standard. The lower limit of the inner pin 32 is 0.25, which is larger than the lower limits of the portions 14j and 14k, and the slope of the stress characteristic line is also large, so it is the lower limit of the entire range. Note that the upper limits of the inner pin 32, the portion 14j, and the portion 14k are limited by the processing limit, and the upper limit will increase as the processing technology improves and the processing limit increases.

[0044] From these, it can be said that when all of the following conditions (1) to (3) are satisfied, the eccentric oscillating gear device 100 satisfies the stress standard determined by market demands in normal applications. (1) The ratio of the pitch circle diameter Dp of the inner pin 32 to the tooth tip diameter De of the external gear 14 (pitch circle diameter Dp / tooth tip diameter De) is 0.77 to 0.85. (2) The ratio of the diameter Dq of the inner pin 32 to the tooth tip diameter De of the external gear 14 (diameter Dq of the inner pin 32 / tooth tip diameter De) is 0.06 to 0.10. (3) An inner pin occupancy rate Eq, which is the ratio of the inner pin 32 to the pitch circumference of the inner pin 32, is 0.25 or more.

[0045] If the inner pin occupancy rate Eq is too large, the distance between the adjacent inner pin holes 14h becomes small, which may cause insufficient rigidity during hole machining and reduced machining accuracy. Therefore, the inner pin occupancy rate Eq in this embodiment is set to less than 0.4. In this case, the reduction in machining accuracy can be suppressed.

[0046] There is a market demand for gear devices having hollow portions large enough to allow wiring such as electric cables to pass through with ease. In the eccentric oscillating gear device 100 of this embodiment, the input shaft 12 having the eccentric portion 12a has a hollow structure having a hollow portion H, and by adopting the above-mentioned configuration, a large-diameter hollow portion H is realized in which the ratio of the diameter Dh of the hollow portion H to the tooth tip diameter De (hollow portion diameter Dh / tooth tip diameter De) is 0.4 or more. In this case, wiring can pass through the hollow portion H with ease, meeting market demands.

[0047] In an eccentric oscillating gear device, the smaller the reduction ratio, the greater the eccentricity of the eccentric portion 12a, and the larger the diameter Dr of the inner pin hole 14h. Therefore, the smaller the reduction ratio, the more difficult it is to increase the diameter of the hollow portion H. However, in the eccentric oscillating gear device 100 of this embodiment, which employs the above-mentioned configuration, a large-diameter hollow portion H (a large-diameter hollow portion H in which the ratio of the diameter Dh of the hollow portion H to the tooth tip diameter De (hollow portion diameter Dh / tooth tip diameter De) is 0.4 or more) can be realized even when the reduction ratio is 30 or less.

[0048] As described above, this disclosure has shown that optimizing the three indexes of pitch circle diameter Dp, inner pin diameter Dq, and inner pin occupancy rate Eq makes it possible to satisfy the inner pin stress standard and the external gear (14j portion, 14k portion) stress standard determined by market demands in normal applications of the eccentric oscillating gear device 100. Furthermore, this disclosure has arrived at the optimal ranges for the three indexes of pitch circle diameter Dp, inner pin diameter Dq, and inner pin occupancy rate Eq, and has shown the results.

[0049] The operation of the eccentric oscillating gear device 100 thus configured will be described. When rotation is transmitted from the motor to the input shaft 12, the eccentric portion 12a of the input shaft 12 rotates around a rotation center line passing through the input shaft 12, and the external gear 14 oscillates via the eccentric bearing 30. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the internal gear 16 are shifted sequentially. As a result, with each rotation of the input shaft 12, one of the external gear 14 and the internal gear 16 rotates by an amount corresponding to the difference in the number of teeth between the external gear 14 and the internal gear 16. In this embodiment, the external gear 14 rotates, and reduced rotation is output from the first carrier 18 and the second carrier 20 via the inner pin 32.

[0050] The following describes the features of the eccentric oscillating gear device 100 configured as above. By satisfying the optimum ranges of the above three indexes, it is possible to provide an eccentric oscillating gear device that allows the diameter Dh of the hollow portion H to be enlarged. The above is a description of the embodiment.

[0051] The above describes in detail the examples of the embodiments of the present invention. The above-mentioned embodiments are merely examples of the implementation of the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are possible within the scope of the invention as defined in the claims. In the above-mentioned embodiments, the contents for which such design changes are possible are described with notations such as "in the embodiment" and "in the embodiment", but this does not mean that design changes are not permitted for contents without such notations. In addition, hatching on the cross sections of the drawings does not limit the material of the objects to which the hatching is applied.

[0052] The following describes the modified examples. In the drawings and description of the modified examples, the same or equivalent components and members as those in the embodiment are denoted by the same reference numerals. Descriptions that overlap with the embodiment will be omitted as appropriate, and the description will focus on configurations that differ from the embodiment.

[0053] [Variations] In the description of the embodiment, an example has been shown in which the casing 22 is configured as a single member, but the casing may be configured as a plurality of members.

[0054] In the description of the embodiment, an example in which the number of external gears 14 is two has been shown, but the number of external gears may be one or three or more.

[0055] In the description of the embodiment, an example has been shown in which the inner pin 32 that contributes to the transmission of the driving force of the external gear 14 is provided as a pin member for connecting the carriers 18, 20. However, a carrier pin that does not contribute to the transmission of the driving force may be provided as a pin member for connecting the carriers 18, 20 in addition to the inner pin 32.

[0056] In the description of the embodiment, an example was shown in which the inner pin 32 is formed integrally with the first carrier 18, but the inner pin 32 may also be formed separately from the first carrier 18 and connected by a fastener such as a bolt.

[0057] In the description of the embodiment, an example was shown in which the number of the inner pins 32 and the number of the inner pin holes 14h were 10, but these numbers may be 9 or less or 11 or more. Also, the number of the inner pins 32 may be less than the number of the inner pin holes 14h.

[0058] In the description of the embodiment, an example has been shown in which the inner rings of the main bearings 24, 26 are formed integrally with the carriers 18, 20, but the inner rings of the main bearings may be separate from the carriers. In addition, the present invention is particularly effective for an eccentric oscillating gear device having a hollow portion H, but is not limited to this and can also be applied to an eccentric oscillating gear device equipped with an input shaft 12 that does not have a hollow portion H.

[0059] Each of the above-described modified examples provides the same functions and effects as the embodiment.

[0060] Any combination of the components and modifications of the above-described embodiments is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the respective embodiments and modifications. [Explanation of symbols]

[0061] 12 input shaft, 12a eccentric portion, 14 external gear, 14b tooth root, 14c center hole, 14d pitch circle, 14e tooth tip, 14h inner pin hole, 16 internal gear, 18 carrier, 18 first carrier, 20 second carrier, 22 casing, 24 first main bearing, 26 second main bearing, 32 inner pin, 32d pitch circle, 100 eccentric oscillating gear device.

Claims

1. An eccentric oscillating gear device comprising: an internal gear; an external gear meshing with the internal gear; an eccentric body that oscillates the external gear; a carrier disposed on an axial side of the external gear; and a plurality of inner pins that are connected to the carrier as either an integral part or separate parts at positions offset from the center of the carrier and that pass through the external gear, a ratio of a pitch circle diameter of the inner pin to a tooth tip diameter of the external gear (pitch circle diameter / tooth tip diameter) of 0.77 to 0.85, a ratio of a diameter of the inner pin to a diameter of the tooth tip of the external gear (inner pin diameter / tooth tip diameter) of 0.06 to 0.10, An eccentric oscillating gear device, wherein an inner pin occupancy rate, which is a ratio of the inner pins to the pitch circumference, is 0.25 or more and less than 0.

4.

2. An eccentric oscillating gear device as described in Claim 1, wherein the eccentric shaft having the eccentric body has a hollow structure.

3. An eccentric oscillating gear device as described in Claim 2, characterized in that the ratio of the hollow portion diameter to the tooth tip diameter (hollow portion diameter / tooth tip diameter) is 0.4 or more.

4. 4. The eccentric oscillating gear device according to claim 1, wherein the reduction ratio is 30 or less.

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