Eccentric oscillation type reduction gear

Abstract

The present invention provides an eccentric oscillating type reduction gear that can increase the connection strength between the first carrier and the second carrier. [Solution] The eccentric oscillating type reduction gear 10 of the embodiment is an eccentric oscillating type reduction gear having an external gear 14, an internal gear 16 that meshes with the external gear 14, and a first carrier 18 and a second carrier 20 arranged on the side of the external gear 14. The first carrier 18 is connected to the second carrier 20 via connecting legs 5 fixed to the first carrier 18. The connecting legs 5 penetrate the external gear 14 axially without contact. The second carrier 20 has a positioning part 4 that positions the connecting legs 5 in the circumferential direction.

Description

Technical Field

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

Background Art

[0002] Reduction gears that reduce and output input rotation are known. For example, Patent Document 1 describes a rotation mechanism having a first carrier that rotates around a rotation axis, a second carrier that is adjacent to the first carrier along the rotation axis, and a bolt that has an axis along the rotation axis and fastens the first carrier and the second carrier.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device described in Patent Document 1, the support portion provided on the first carrier extends in the axial direction, and the tip portion of the support portion contacts the second carrier in the axial direction. A female screw portion and a positioning recess for inserting a positioning pin are formed at the tip portion of the support portion. A bolt is inserted into a fitting hole provided in the second carrier, and this bolt is tightened to the female screw portion of the support portion, and at the same time, a positioning pin is inserted into a through hole provided in the second carrier and inserted into the insertion recess, whereby the first carrier and the second carrier are positioned and integrated.

[0005] In the device described in Patent Document 1, the placement and size of the bolts are restricted due to the presence of position-regulating recesses in the support column, making it difficult to increase the bolt size. Therefore, this device cannot increase the connection strength between the first carrier and the second carrier. In addition, the position-regulating pins are thin and therefore contribute little to the connection strength. As a result, there is a problem in that sufficient torque cannot be transmitted between the first carrier and the second carrier. Patent Document 1 does not provide sufficient disclosure from the viewpoint of increasing the connection strength between the first carrier and the second carrier.

[0006] This invention has been made in view of these problems, and one of its objectives is to provide an eccentric oscillating type reduction gear that can increase the connection strength between the first carrier and the second carrier. [Means for solving the problem]

[0007] To solve the above problems, an eccentric oscillating type reduction gear according to one aspect of the present invention is an eccentric oscillating type reduction gear having an external gear, an internal gear that meshes with the external gear, and a first carrier and a second carrier arranged on the side of the external gear, wherein the first carrier is connected to the second carrier via a connecting leg fixed to the first carrier, the connecting leg penetrates the external gear axially without contact, and the second carrier has a positioning part that positions the connecting leg in the circumferential direction.

[0008] Furthermore, any combination of the above components, or in which the components or expressions of the present invention are mutually substituted among methods, systems, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an eccentric oscillating type reduction gear that can increase the connection strength between the first carrier and the second carrier. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side cross-sectional view showing an eccentric oscillating type reduction gear of an embodiment. [Figure 2] Figure 1 is a front view showing the first carrier of the eccentric oscillating type reduction gear. [Figure 3] This is a rear view showing the second carrier of the eccentric oscillating type reduction gear shown in Figure 1. [Modes for carrying out the invention]

[0011] The present invention will be described below with reference to the drawings, based on preferred embodiments. In embodiments and modifications, the same or equivalent components and members will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, the dimensions of the members in each drawing will be enlarged or reduced as appropriate to facilitate understanding. Furthermore, some members that are not important for explaining the embodiments will be omitted from the drawings.

[0012] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves.

[0013] [Embodiment] The configuration of the eccentric oscillating type reduction gear 10 according to this embodiment will be described below with reference to Figure 1. Figure 1 is a side cross-sectional view showing the eccentric oscillating type reduction gear 10 of this embodiment. The eccentric oscillating type reduction gear 10 of this embodiment is a so-called distribution type eccentric oscillating type reduction gear. This eccentric oscillating type reduction gear 10 is configured to generate rotation of one of the internal gears and the external gears by oscillating the external gear that meshes with the internal gear, and to output the resulting rotation component from the output member to the driven device.

[0014] The eccentric oscillating reduction gear 10 is an eccentric oscillating reduction gear having an external gear 14, an internal gear 16 that meshes with the external gear 14, and a first carrier 18 and a second carrier 20 positioned on the side of the external gear 14. The first carrier 18 is connected to the second carrier 20 via connecting legs 5 fixed to the first carrier 18. The connecting legs 5 penetrate axially through a cavity provided in the external gear 14 without contact. In other words, the connecting legs 5 are not shaft members that contact the external gear 14 to extract power. The second carrier 20 has a positioning part 4 that positions the connecting legs 5 in the circumferential direction. The positioning part 4 and the connecting legs 5 will be described later.

[0015] The eccentric oscillating reduction gear 10 further comprises an input gear 70, a crankshaft 12, a casing 22, and main bearings 24 and 26. Hereinafter, the direction along the central axis La of the internal gear 16 will be referred to as the "axial direction," and the circumferential and radial directions of the circle centered on that central axis La will be referred to as the "circumferential direction" and "radial direction," respectively. Also, for convenience, hereafter, one side of the axial direction (right side in the figure) will be referred to as the input side, and the other side (left side in the figure) will be referred to as the non-input side.

[0016] Three input gears 70 are arranged around the central axis La of the internal gear 16. The three input gears 70 are positioned at equal intervals of 120°, offset from the central axis La. Figure 1 shows only one input gear 70. Three crankshafts 12 are provided, corresponding to the three input gears 70. The crankshafts 12 are inserted through the center of the input gears 70 and support the input gears 70. A pair of crankshaft bearings 34 are provided on both axial sides of the crankshaft 12. The crankshafts 12 are provided so as to be rotatable integrally with the input gears 70. The three input gears 70 mesh with external teeth (not shown) provided on a rotating shaft (not shown) located on the central axis La. Rotational power is transmitted to this rotating shaft from a drive device (not shown), and the rotation of this rotating shaft causes the input gears 70 to rotate integrally with the crankshafts 12. The drive device is, for example, a motor, gear motor, engine, etc.

[0017] The crankshaft 12 of the present embodiment is an eccentric shaft having a plurality of eccentric portions 12a for swinging the external gear 14. The axis of the eccentric portion 12a is eccentric with respect to the rotation center line of the crankshaft 12. In the present embodiment, two eccentric portions 12a are provided, and the eccentric phases of the adjacent eccentric portions 12a are shifted by 180°.

[0018] The input side of the crankshaft 12 is supported by the second carrier 20 via the crankshaft bearing 34, and the anti-input side thereof is supported by the first carrier 18 via the crankshaft bearing 34. The crankshaft bearing 34 on the anti-input side is fitted and supported in the crankshaft hole 18h of the first carrier 18, and the crankshaft bearing 34 on the input side is fitted and supported in the crankshaft hole 20h of the second carrier 20. That is, the crankshaft 12 is rotatably supported with respect to the first carrier 18 and the second carrier 20. The crankshaft bearing 34 is not particularly limited in its configuration, but in this example, it is a roller bearing having a cylindrical rolling element.

[0019] The internal gear 16 meshes with the external gear 14. The internal gear 16 of the present embodiment has an internal gear main body 16a integrated with the casing 22, and external pins 17 arranged in a plurality of pin grooves formed at intervals in the circumferential direction on the internal gear main body 16a. The external pin 17 is a cylindrical pin member rotatably supported by the internal gear main body 16a. The external pin 17 may be a hollow member, but in the present embodiment, it is a solid member. The external pin 17 constitutes the internal teeth of the internal gear 16. The number of external pins 17 (the number of internal teeth) of the internal gear 16 is slightly (by 1 in this example) more than the number of external teeth of the external gear 14.

[0020] The external gear 14 is provided individually corresponding to each of the plurality of eccentric portions 12a. The external gear 14 is rotatably supported by the corresponding eccentric portion 12a via the eccentric roller 32. In the external gear 14, three shaft holes 14p and three swing holes 14j are formed at a predetermined interval at positions offset from its axis.

[0021] The shaft holes 14p are provided at 120° intervals at the same radial position with respect to each other. The shaft holes 14p penetrate axially, and the connection legs 5 are inserted therethrough. The shaft holes 14p are formed larger than the outer diameter of the connection legs 5 and have a size that does not contact the connection legs 5.

[0022] The swing holes 14j are provided at 120° intervals at the same radial position with respect to each other. The swing holes 14j penetrate axially, and the eccentric portions 12a of the crankshaft 12 are inserted therethrough. The swing holes 14j are formed larger than the outer diameter of the eccentric portions 12a, and a plurality of eccentric rollers 34 are interposed between the swing holes 14j and the eccentric portions 12a. The plurality of eccentric rollers 34 are arranged at substantially equal intervals around the eccentric portions 12a and smoothly transmit the eccentric motion of the eccentric portions 12a to the swing holes 14j.

[0023] The external gear 14 is provided with a central hole 14h that penetrates the radial center. The central hole 14h is a hole provided at the radial center of the external gear 14. Although there is no limitation on the shape of the central hole 14h, the central hole 14h in this example is circular.

[0024] Wave-shaped teeth are formed on the outer periphery of the external gear 14, and by moving while contacting the internal gear 16, the external gear 14 can swing in a plane with the central axis as the normal.

[0025] The first carrier 18 and the second carrier 20 are arranged on the axial side portions of the external gear 14. The first carrier 18 is arranged on the side portion of the external gear 14 on the non-input side. The second carrier 20 is arranged on the side portion of the external gear 14 on the input side. When collectively referring to the first carrier 18 and the second carrier 20, it is denoted as "carrier". The carrier is rotatably supported by the casing 22 via the first main bearing 24 and the second main bearing 26. The carrier as a whole has a hollow disk shape or a cylindrical shape. The carrier rotatably supports the crankshaft 12 via the crankshaft bearing 34.

[0026] The first carrier 18 and the second carrier 20 have central holes 18j and 20j at their radial centers. When referring to the central holes 18j and 20j collectively, they are referred to as "central holes".

[0027] The casing 22 is a hollow cylindrical shape overall, and an internal gear 16 is provided on its inner circumference. A flange is provided on the outer circumference of the casing 22. Through holes and tapped holes are provided in the flange, spaced apart in the circumferential direction. These holes are used to connect the casing 22 to external members and driven devices.

[0028] The casing 22 is provided with a recess 22m for accommodating the outer ring 30 of the first main bearing 24 and a recess 22n for accommodating the outer ring 30 of the second main bearing 26. The casing 22 and the carrier are configured to rotate relative to each other via the first main bearing 24 and the second main bearing 26.

[0029] The main bearings 24 and 26 include a first main bearing 24 positioned between the first carrier 18 and the casing 22, and a second main bearing 26 positioned between the second carrier 20 and the casing 22. The main bearings 24 and 26 of this embodiment include a plurality of rolling elements 28 and a retainer (not shown). The plurality of rolling elements 28 are spaced apart in the circumferential direction. The rolling elements 28 of this embodiment are spherical. The retainer maintains the relative positions of the plurality of rolling elements 28 and rotatably supports the plurality of rolling elements 28. The main bearings 24 and 26 may be roller bearings or cross roller bearings.

[0030] In this embodiment, the main bearings 24 and 26 are equipped with an outer ring 30 having a rolling surface for the rolling elements 28, but without an inner ring. The inner rolling surfaces of the main bearings 24 and 26 are provided on the outer circumferential surfaces of the first carrier 18 and the second carrier 20, instead of an inner ring. The outer ring 30 is fixed to the casing 22 by a fit such as clearance fit, interference fit, or intermediate fit.

[0031] One of the first carrier 18 and the casing 22 functions as an output member that outputs rotational power to the driven device, while the other functions as a fixed member that is fixed to an external member for supporting the eccentric oscillating type reduction gear 10. In this embodiment, the output member is the first carrier 18 and the fixed member is the casing 22. Alternatively, the casing 22 may be the output member and the first carrier 18 may be the fixed member.

[0032] The connecting leg 5 and positioning part 4 will be explained with reference to Figures 2 and 3. Figure 2 is a front view of the first carrier 18, as seen from the input side. Figure 3 is a rear view of the second carrier 20, as seen from the opposite input side. The first carrier 18 and the second carrier 20 are connected via the connecting leg 5. In other words, the connecting leg 5 functions as a connecting part that contributes to the connection between the first carrier 18 and the second carrier 20. In this embodiment, the connecting leg 5 is a shaft-shaped portion that extends axially from the first carrier 18 toward the second carrier 20 and is formed integrally with the first carrier 18.

[0033] The connecting leg 5 is inserted through the shaft hole 14p formed in the external gear 14 with a gap between them. The input-side tip of the connecting leg 5 is in contact with the non-input end face of the second carrier 20 and is fixed to the second carrier 20. When the connecting leg 5 is fixed to the second carrier 20, a part of the connecting leg 5 is positioned by the positioning part 4 and bolted in place by a bolt 18p.

[0034] The configuration of the positioning part 4 is not limited as long as the connecting leg 5 can be positioned in the circumferential direction. In this embodiment, the positioning part 4 includes a projection 42 that protrudes from the connecting leg 5. As shown in Figure 1, the projection 42 in this example includes a portion that extends toward the non-input side and has a shape that encloses the outer circumference 56 of the connecting leg 5. In this example, the projection 42 is provided continuously in the circumferential direction, but it may also be provided intermittently.

[0035] The positioning section 4 in this example includes a recess 44 that accommodates the connecting leg 5. The recess 44 has an arc-shaped inner circumferential surface that surrounds the connecting leg 5. As an example, the positioning section 4 in this example is positioned by the contact portion 57 of the outer circumference 56 of the connecting leg 5 contacting the recess 44, as shown in Figure 2. In the positioning section 4 in this example, the outer circumference 56 of the connecting leg 5 contacts the recess 44 at multiple points. In this example, it contacts the recess 44 at three contact portions 57, but the number of contact portions 57 can be one or more.

[0036] The connecting leg 5 may be cylindrical or non-cylindrical. If it is non-cylindrical, its shape can be designed according to the arrangement of other components of the reduction gear, such as the crankshaft 12, and its strength can be improved. In this example, the connecting leg 5 is a roughly triangular prism formed by moving a triangle with large radii at its corners in the axial direction. The connecting leg 5 may also be a polygonal prism with four or more corners, such as a quadrangular prism.

[0037] In this example, the outer contour of the tip portion of the connecting leg 5, including the contact portion 57, which is housed in the recess 44, is non-circular, such as a polygon or ellipse. The outer contour of the cross-section along a plane perpendicular to the axial direction of the connecting leg 5 is a triangle with large radii at its corners, and each corner functions as a contact portion 57. From the viewpoint of ensuring positioning accuracy, the contact portion 57, which is the part of the connecting leg 5 that contacts the recess 44, is a machined surface 58. For example, the connecting leg 5 can be formed by die casting, and the portion that becomes the contact portion 57 can be machined to form the machined surface 58.

[0038] When connecting the first carrier 18 and the second carrier 20, the tip portion of the connecting leg 5, including the contact portion 57, is fitted into the recess 44, and the leg is positioned with the contact portion 57 in contact with the recess 44. In this positioned state, the connecting leg 5 is bolted to the second carrier 20 by passing the bolt 18p through the bolt hole 46 of the second carrier 20 from the input side and screwing it into the female screw hole 52 provided on the end face of the connecting leg 5.

[0039] The operation of the eccentric oscillating reduction gear 10 configured as described above will now be explained. When rotational power is transmitted from the drive unit to the rotating shaft, the rotational power is distributed from the rotating shaft to a plurality of input gears 70, and each input gear 70 rotates in the same phase. As each input gear 70 rotates, the eccentric portion 12a of the crankshaft 12 rotates around the rotational center line passing through the crankshaft 12, and the external gear 14 oscillates due to this eccentric portion 12a. As the external gear 14 oscillates, the meshing positions of the external gear 14 and the external pins 17 of the internal gear 16 shift sequentially. As a result, with each rotation of the crankshaft 12, one of the external gear 14 or internal gear 16 rotates by an amount equivalent to the difference between the number of teeth of the external gear 14 and the number of external pins 17 of the internal gear 16. In this embodiment, the external gear 14 rotates, and a reduction rotation is output from the first carrier 18.

[0040] The features of the eccentric oscillating type reduction gear 10 configured as described above will now be explained. The eccentric oscillating type reduction gear 10 is an eccentric oscillating type reduction gear having an external gear 14, an internal gear 16 that meshes with the external gear 14, and a first carrier 18 and a second carrier 20 arranged on the side of the external gear 14. The first carrier 18 is connected to the second carrier 20 via connecting legs 5 fixed to the first carrier 18. The connecting legs 5 penetrate the external gear 14 axially without contact. The second carrier 20 has a positioning part 4 that positions the connecting legs 5 in the circumferential direction.

[0041] With this configuration, the connecting leg 5 is positioned by the positioning unit 4, so it is not necessary to provide space for a position regulating pin in the connecting leg 5. This allows for larger or more numerous connecting bolts to increase the connection strength between the first carrier 18 and the second carrier 20. As a result, torque transmission capacity can be easily ensured between the first carrier 18 and the second carrier 20. Since it is not necessary to provide space for a position regulating pin in the connecting leg 5, the connecting leg 5 can be made smaller, which is advantageous for miniaturizing the eccentric oscillating type reduction gear 10. Furthermore, since it is not necessary to provide a hole for a position regulating pin in the connecting leg 5, it is advantageous in terms of the strength of the connecting leg 5. In addition, since it is not necessary to provide a position regulating pin in the connecting leg 5, productivity is improved.

[0042] As an example, the positioning part 4 includes a projection 42 that protrudes from the connecting leg 5. In this case, the projection 42 and the connecting leg 5 can be brought into contact to restrict their position.

[0043] For example, the positioning section 4 includes a recess 44 for accommodating the connecting leg 5. In this case, accommodating the connecting leg 5 in the recess 44 allows for temporary positioning, which is advantageous in terms of productivity.

[0044] For example, the positioning unit 4 is positioned by the outer circumference 56 of the connecting leg 5 contacting the recess 44. In this case, the recess 44 and the connecting leg 5 can be brought into contact to restrict their position.

[0045] For example, the shape of the recess 44 of the positioning part 4 is a circular shape with a portion of the outer circumference on the radially outer side missing, and its shape differs from the outer contour of the connecting leg 5. In this case, because the recess 44 is a circular shape with a portion of the outer circumference missing, the shape is simple and easy to manufacture, and precision control can be achieved by controlling the diameter of the circle, the roundness, the coordinates of the center of the circle, etc., which is advantageous in terms of management man-hours.

[0046] Here, we will explain the reason for cutting off a portion of the outer circumference of the recess 44 to create an opening. Considering the torque and strength of the connecting leg 5, a triangular prism shape with a large radius at the corners that are radially thicker is advantageous for the connecting leg 5. In other words, it is easier to machine the outer circumference of a triangular prism shape with a large radius at the corners as a circle centered on the central axis of the reducer. In this case, if the recess 44 is made circular and the circumferential portion of the triangular prism shape with a large radius at the corners comes into contact with the inner circumference, the outer circumference will be left open, making it easier to machine than if the outer circumference of the recess 44 were not cut off.

[0047] For example, in the positioning section 4, the outer circumference 56 of the connecting leg 5 contacts the recess 44 at multiple points, and the outer contour of the part of the connecting leg 5 that is housed in the recess 44 is non-circular. In this case, the parts requiring machining precision can be limited to the contact points of the connecting leg 5, making manufacturing easier compared to ensuring overall machining precision.

[0048] For example, the positioning section 4 has a machined surface 58 at the point where it contacts the recess 44 of the connecting leg 5. In this case, by making that portion a machined surface 58, the positioning accuracy can be improved compared to when it is an unmachined surface.

[0049] The embodiments of the present invention have been described in detail above. The embodiments described above are merely examples of how to implement 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 as long as they do not depart from the spirit of the invention as defined in the claims. In the embodiments described above, such design changes are described with notations such as "of the embodiments" or "in the embodiments," but this does not mean that design changes are not permitted for contents without such notations. Furthermore, the hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied.

[0050] The following describes modified examples. In the drawings and descriptions of the modified examples, components and parts that are the same or equivalent as those in the embodiments are denoted by the same reference numerals. Descriptions that overlap with those in the embodiments will be omitted as appropriate, and the descriptions will focus on the configurations that differ from those in the embodiments.

[0051] [Differentiation] In the above description, an example was shown in which the connecting leg 5 is integrally formed with the first carrier 18, but the present invention is not limited to this. For example, the connecting leg may be formed as a separate component from the first carrier and fixed to the first carrier by fixing methods such as bolting or welding.

[0052] In the above description, an example was shown in which two bolts are used to connect one connecting leg 5 to the second carrier 20, but the present invention is not limited to this. The number of bolts may be one or three or more. From the viewpoint of productivity, it is preferable that the number of bolts be five or less.

[0053] In the above description, an example was shown in which the central hole 20j of the second carrier 20 is a through hole, but the present invention is not limited to this. The central hole 20j may be a non-through hole with the input side closed. For example, the central hole 20j may be a recess that is axially recessed from the non-input side of the second carrier 20.

[0054] In the above description, the number of crankshafts 12 and input gears 70 was set to 3, but the present invention is not limited to this. The number of crankshafts 12 and input gears 70 may be 1, 2, or 4 or more.

[0055] The above description shows an example with two external gears 14, but the present invention is not limited to this. Three or more external gears 14 may be provided. For example, the crankshaft may be provided with three eccentric portions 12a, each 120° apart in phase, and three external gears 14 may be provided that are oscillated by these three eccentric portions 12a. Alternatively, there may be only one external gear 14.

[0056] The above description shows an example in which the second main bearing 26 and the first main bearing 24 do not have inner rings, but the present invention is not limited thereto. The second main bearing 26 and the first main bearing 24, or one or both, may be bearings having inner rings.

[0057] Each of the above-described modifications produces the same functions and effects as the above-described embodiments.

[0058] Any combination of the embodiments and modifications described above is also useful as an embodiment of the present invention. The new embodiments resulting from these combinations possess the combined effects of each of the embodiments and modifications that are combined. [Explanation of symbols]

[0059] 4 Positioning part, 5 Connecting leg, 14 External gear, 16 Internal gear, 18 First carrier, 18p Bolt, 20 Second carrier, 42 Protrusion, 44 Recess, 46 Bolt hole, 52 Female screw hole, 56 Outer circumference, 57 Contact part, 58 Machined surface, 10 Eccentric oscillating type reduction gear.

Claims

1. An eccentric oscillating reduction gear having an external gear, an internal gear that meshes with the external gear, and a first carrier and a second carrier arranged on the side of the external gear, The first carrier is connected to the second carrier via connecting legs fixed to the first carrier. The connecting leg penetrates the external gear axially without contact, The second carrier is an eccentric oscillating type reduction gear having a positioning part that positions the connecting leg in the circumferential direction.

2. The eccentric oscillating type reduction gear according to claim 1, wherein the positioning portion includes a projection that protrudes from the connecting leg.

3. The eccentric oscillating type reduction gear according to claim 1, wherein the positioning portion includes a recess for accommodating the connecting leg.

4. The eccentric oscillating type reduction gear according to claim 3, wherein the positioning portion is positioned by the outer circumference of the connecting leg contacting the recess.

5. The positioning portion is such that the outer circumference of the connecting leg contacts the recess at multiple locations. The eccentric oscillating type reduction gear according to claim 4, wherein the outer contour of the portion of the connecting leg that is housed in the recess is non-circular.

6. The eccentric oscillating type reduction gear according to claim 4, wherein the positioning portion is a machined surface in the portion of the connecting leg that contacts the recess.

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