Eccentric swing type speed reduction device

Abstract

To provide an eccentric swing type speed reduction device capable of improving the connection strength between a first bracket and a second bracket. An eccentric swing type speed reduction device (10) according to an embodiment has an external gear (14), an internal gear (16) engaged with the external gear (14), and a first bracket (18) and a second bracket (20) disposed at the side of the external gear (14). The first bracket (18) is connected to the second bracket (20) via a connecting leg (5) fixed to the first bracket (18). The connecting leg (5) penetrates the external gear (14) in the axial direction in a non-contact manner. The second bracket (20) has a positioning portion (4) that positions the connecting leg (5) in the circumferential direction.

Description

[0001] This application claims priority to Japanese Patent Application No. 2024-209127, filed on November 29, 2024. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to an eccentric oscillating type deceleration device. Background Technology

[0003] A speed reduction device is known to reduce the output speed of an input rotation. For example, Patent Document 1 describes a rotating mechanism having: a first bracket that rotates about a rotation axis; a second bracket adjacent to the first bracket along the rotation axis; and a bolt having an axis along the rotation axis and fastening the first bracket and the second bracket.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2023-090311

[0005] In the device described in Patent Document 1, a support portion provided in the first bracket extends along the axial direction, and the front end of the support portion contacts the second bracket along the axial direction. An internal thread portion and a limiting recess for inserting a limiting pin are formed at the front end of the support portion. A bolt is inserted into the fitting hole provided in the second bracket and screwed into the internal thread portion of the support portion. A limiting pin is inserted into the through hole provided in the second bracket and inserted into the insertion recess, thereby positioning and integrating the first and second brackets.

[0006] In the device described in Patent Document 1, a limiting recess is provided in the support portion, thereby restricting the arrangement or size of the bolts and making it difficult to increase the bolt size. Therefore, in this device, it is impossible to improve the connection strength between the first bracket and the second bracket. Furthermore, since the limiting pin is relatively thin, its contribution to the connection strength is small. As a result, there is a problem that torque cannot be adequately transmitted between the first bracket and the second bracket. Patent Document 1 does not provide sufficient disclosure regarding improving the connection strength between the first bracket and the second bracket. Summary of the Invention

[0007] The present invention was made in view of this problem, and its object is to provide an eccentric swing type deceleration device that can improve the connection strength between the first bracket and the second bracket.

[0008] To address the aforementioned issues, an eccentric oscillating speed reduction device according to one embodiment of the present invention includes an external gear, an internal gear meshing with the external gear, and a first bracket and a second bracket disposed on the side of the external gear. The first bracket is connected to the second bracket via a connecting leg fixed to the first bracket. The connecting leg passes through the external gear axially in a non-contact manner. The second bracket has a positioning portion for positioning the connecting leg in the circumferential direction.

[0009] Furthermore, any combination of the above-mentioned constituent elements, or the substitution of the constituent elements or expressions of the present invention among methods, systems, etc., are also valid embodiments of the present invention.

[0010] Invention Effects

[0011] According to the present invention, an eccentric swing-type deceleration device is provided that can improve the connection strength between the first bracket and the second bracket. Attached Figure Description

[0012] Figure 1 This is a side sectional view showing an embodiment of the eccentric oscillating type deceleration device.

[0013] Figure 2 It is shown Figure 1 Front view of the first bracket of the eccentric swing type speed reducer.

[0014] Figure 3 It is shown Figure 1 Rear view of the second bracket of the eccentric swing type speed reducer.

[0015] In the figure: 4-positioning part, 5-connecting foot, 14-external gear, 16-internal gear, 18-first bracket, 18p-bolt, 20-second bracket, 42-protrusion, 44-recess, 46-bolt hole, 52-internal thread hole, 56-outer periphery, 57-contact part, 58-machined surface, 10-eccentric swing type speed reducer. Detailed Implementation

[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments and modifications, the same or equivalent constituent elements and components are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. Furthermore, for ease of understanding, the dimensions of components are shown in the drawings at appropriate enlargements or reductions. Also, in the drawings, parts of components that are not important for illustrating the embodiments are omitted from the illustration.

[0017] Furthermore, terms including ordinal numbers such as 1 and 2 are used to describe various constituent elements, but these terms are used only for the purpose of distinguishing one constituent element from other constituent elements, and do not limit the constituent elements.

[0018] [Implementation Method]

[0019] The following is for reference. Figure 1 The structure of the eccentric swing type deceleration device 10 according to the embodiment will be described. Figure 1 This is a side sectional view showing the eccentric oscillating type speed reducer 10 according to the embodiment. The eccentric oscillating type speed reducer 10 of this embodiment is a so-called distributed eccentric oscillating type speed reducer. The eccentric oscillating type speed reducer 10 is configured such that by oscillating the external gear meshing with the internal gear, one of the internal gear and the external gear will rotate, and the resulting rotation component will be output from the output member to the driven device.

[0020] The eccentric oscillating type speed reducer 10 includes an external gear 14, an internal gear 16 meshing with the external gear 14, and a first bracket 18 and a second bracket 20 disposed on the side of the external gear 14. The first bracket 18 is connected to the second bracket 20 via a connecting leg 5 fixed to it. The connecting leg 5 is provided axially through the cavity of the external gear 14 in a non-contact manner. That is, the connecting leg 5 is not a shaft component that contacts the external gear 14 to output power. The second bracket 20 has a positioning part 4 for positioning the connecting leg 5 in the circumferential direction. The positioning part 4 and the connecting leg 5 will be described later.

[0021] The eccentric oscillating type reduction gear 10 also includes an input gear 70, a crankshaft 12, a housing 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 direction and radial direction of the circle centered on this central axis La will be designated as the "circumferential direction" and "radial direction," respectively. Furthermore, for ease of explanation, the side along 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 opposite input side.

[0022] Three input gears 70 are arranged around the central axis La of the internal gear 16. The three input gears 70 are equally spaced at 120° intervals at positions offset from the central axis La. Figure 1 Only one input gear 70 is shown. Three crankshafts 12 are provided, corresponding to the three input gears 70. The crankshafts 12 pass through the central portion of the input gears 70 and support them. A pair of crankshaft bearings 34 are provided on both axial sides of the crankshafts 12. The crankshafts 12 are configured to rotate integrally with the input gears 70. The three input gears 70 mesh with the external teeth (not shown) of a rotating shaft (not shown) located on the central axis La. Rotational power is transmitted to this rotating shaft (not shown), and through the rotation of this rotating shaft, the input gears 70 rotate integrally with the crankshafts 12. The driving device is, for example, a motor, a geared motor, or an engine.

[0023] The crankshaft 12 in this embodiment is an eccentric shaft having multiple eccentric portions 12a for oscillating the external gear 14. The axis of the eccentric portion 12a is eccentric relative to the rotation center line of the crankshaft 12. In this embodiment, two eccentric portions 12a are provided, and the eccentric phases of adjacent eccentric portions 12a are offset by 180°.

[0024] The input side of crankshaft 12 is supported on the second bracket 20 via crankshaft bearing 34, and the opposite input side is supported on the first bracket 18 via crankshaft bearing 34. The crankshaft bearing 34 on the opposite input side is inserted into and supported in the crankshaft bore 18h of the first bracket 18, and the crankshaft bearing 34 on the input side is inserted into and supported in the crankshaft bore 20h of the second bracket 20. That is, crankshaft 12 is supported to be freely rotatable relative to the first bracket 18 and the second bracket 20. The structure of crankshaft bearing 34 is not particularly limited, but in this example, it is a roller bearing with cylindrical rolling elements.

[0025] The internal gear 16 meshes with the external gear 14. In this embodiment, the internal gear 16 has an internal gear body 16a integrated with the housing 22 and an outer pin 17 disposed in the internal gear body 16a with a plurality of pin slots spaced apart circumferentially. The outer pin 17 is a cylindrical pin member rotatably supported on the internal gear body 16a. The outer pin 17 may be a hollow member, but in this embodiment it is a solid member. The outer pin 17 constitutes the internal teeth of the internal gear 16. The number of outer pins 17 (number of internal teeth) of the internal gear 16 is slightly more than the number of external teeth of the external gear 14 (one more in this example).

[0026] The external gear 14 is individually provided in correspondence with each of the plurality of eccentric portions 12a. The external gear 14 is rotatably supported on the corresponding eccentric portion 12a via eccentric rollers 32. In the external gear 14, three shaft holes 14p and three swing holes 14j are formed at predetermined intervals at positions offset from its axis.

[0027] The shaft holes 14p are arranged at 120° intervals at the same radial position. The shaft holes 14p extend axially through the shaft hole for the connecting leg 5 to be inserted through. The shaft holes 14p are formed to be larger than the outer diameter of the connecting leg 5 and have a size that does not contact the connecting leg 5.

[0028] The swing holes 14j are arranged at 120° intervals at the same radial position. The swing holes 14j extend axially and allow the eccentric portion 12a of the crankshaft 12 to be inserted through them. The swing holes 14j are formed to be larger than the outer diameter of the eccentric portion 12a, and a plurality of eccentric rollers 32 are provided between the swing holes 14j and the eccentric portion 12a. The plurality of eccentric rollers 32 are arranged at approximately equal intervals around the eccentric portion 12a, so as to smoothly transmit the eccentric movement of the eccentric portion 12a to the swing holes 14j.

[0029] A central hole 14h is provided in the external gear 14, extending radially through its center. The central hole 14h is a hole located radially at the center of the external gear 14. The shape of the central hole 14h is not limited, but in this example, the central hole 14h is circular.

[0030] The outer gear 14 has wave-shaped teeth formed on its outer periphery. Through these teeth, it contacts and moves with the inner gear 16, allowing the outer gear 14 to oscillate in a plane with the central axis as the normal.

[0031] The first bracket 18 and the second bracket 20 are disposed on the axial side of the external gear 14. The first bracket 18 is disposed on the side opposite to the input of the external gear 14. The second bracket 20 is disposed on the side of the input of the external gear 14. When collectively referred to as the first bracket 18 and the second bracket 20, they are marked as "brackets". The brackets are rotatably supported on the housing 22 via the first main bearing 24 and the second main bearing 26. The brackets are generally hollow disc-shaped or cylindrical. The brackets rotatably support the crankshaft 12 via the crankshaft bearing 34.

[0032] The first bracket 18 and the second bracket 20 have central holes 18j and 20j at their radial centers. When referring to the central holes 18j and 20j collectively, they are marked as "central holes".

[0033] The housing 22 is generally hollow and cylindrical, with an internal gear 16 disposed on its inner periphery. A flange is disposed on the outer periphery of the housing 22. Through holes or threaded holes are disposed at intervals along the circumference of the flange. These holes are used to connect the housing 22 to external components or driven devices.

[0034] The housing 22 has 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 housing 22 and the bracket are configured to rotate relative to each other via the first main bearing 24 and the second main bearing 26.

[0035] The main bearings 24 and 26 include a first main bearing 24 disposed between the first bracket 18 and the housing 22, and a second main bearing 26 disposed between the second bracket 20 and the housing 22. In this embodiment, the main bearings 24 and 26 have a plurality of rolling elements 28 and a cage (not shown). The plurality of rolling elements 28 are arranged at intervals along the circumference. In this embodiment, the rolling elements 28 are balls. The cage holds 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 can be roller bearings or crossed roller bearings.

[0036] In this embodiment, the main bearings 24 and 26 have an outer ring 30 with rolling surfaces having rolling elements 28, but no inner ring. The inner rolling surfaces of the main bearings 24 and 26 are provided on the outer peripheral surfaces of the first bracket 18 and the second bracket 20, replacing the inner ring. The outer ring 30 is fixed to the housing 22 by a clearance fit, interference fit, or transition fit.

[0037] One of the first bracket 18 and the housing 22 functions as an output component that outputs rotational power to the driven device, while the other functions as a fixed component that is fixed to an external component used to support the eccentric oscillating type speed reducer 10. In this embodiment, the output component is the first bracket 18, and the fixed component is the housing 22. Alternatively, the housing 22 can be used as the output component, and the first bracket 18 as the fixed component.

[0038] refer to Figure 2 , Figure 3 The connecting foot 5 and the positioning part 4 will be described. Figure 2 This is a front view of the first bracket 18, viewed from the input side. Figure 3 This is a rear view showing the second bracket 20, viewed from the side opposite the input. The first bracket 18 and the second bracket 20 are connected via a connecting leg 5. In other words, the connecting leg 5 functions as a connecting portion that facilitates the connection between the first bracket 18 and the second bracket 20. In this embodiment, the connecting leg 5 is a shaft-like portion extending axially from the first bracket 18 toward the second bracket 20, and is integrally formed with the first bracket 18.

[0039] The connecting leg 5 is inserted through the shaft hole 14p formed on the external gear 14 with a gap between it and the shaft hole 14p. The front end of the input side of the connecting leg 5 contacts the end face opposite to the input side of the second bracket 20, and the connecting leg 5 is fixed to the second bracket 20. When the connecting leg 5 is fixed to the second bracket 20, a portion of the connecting leg 5 is positioned by the positioning part 4 and is threaded by the bolt 18p.

[0040] The structure of the positioning part 4 is not limited as long as the connecting leg 5 can be positioned circumferentially. In this embodiment, the positioning part 4 includes a protrusion 42 that protrudes relative to the connecting leg 5. Figure 1 As shown, the protrusion 42 in this example includes a portion extending toward the opposite side of the input and has a shape that surrounds the outer periphery 56 of the connecting foot 5. The protrusion 42 in this example is continuously provided in the circumferential direction, but it can also be provided intermittently.

[0041] In this example, the positioning part 4 includes a recess 44 for receiving the connecting leg 5. The recess 44 has an arc-shaped inner circumferential surface surrounding the connecting leg 5. As an example, such as Figure 2As shown, in this example, the positioning part 4 is positioned by contacting the recess 44 with the contact portion 57 of the outer periphery 56 of the connecting leg 5. In this example, the outer periphery 56 of the connecting leg 5 contacts the recess 44 at multiple locations. In this example, the recess 44 is contacted by three contact portions 57, but the number of contact portions 57 need to be more than one.

[0042] The connecting leg 5 can be cylindrical or non-cylindrical. If it is non-cylindrical, its shape can be designed according to the configuration of other components of the reducer, such as the crankshaft 12, thereby improving strength. In this example, the connecting leg 5 is an approximate triangular prism formed by moving a triangle with a large radius at its corners axially. The connecting leg 5 can also be a polygonal prism with four or more corners, such as a quadrangular prism.

[0043] In this example, the outer contour of the portion of the connecting leg 5 that is accommodated in the recess 44 (i.e., the front end portion including the contact portion 57) is non-circular, such as a polygon or an ellipse. The outer contour of the connecting leg 5 along a plane orthogonal to the axial direction is a triangle with large radius angles at its corners, each corner functioning as the contact portion 57. From the viewpoint of ensuring positioning accuracy, the portion of the connecting leg 5 that contacts the recess 44, i.e., the contact portion 57, is a machined surface 58. For example, the connecting leg 5 can be formed by die casting, and the machined surface 58 can be formed by machining the portion that becomes the contact portion 57.

[0044] When the first bracket 18 and the second bracket 20 are connected together, the front end portion of the connecting leg 5, including the contact portion 57, is fitted into the recess 44 and positioned so that the contact portion 57 is in contact with the recess 44. In this positioned state, the connecting leg 5 is threadedly fixed to the second bracket 20 by passing the bolt 18p through the bolt hole 46 of the second bracket 20 from the input side and screwing it into the internal thread hole 52 provided on the end face of the connecting leg 5.

[0045] The operation of the eccentric oscillating reduction gear 10 configured as described above will be explained. If rotational power is transmitted from the drive unit to the rotating shaft, the rotational power is distributed from the rotating shaft to multiple input gears 70, each input gear 70 rotating in the same phase. As each input gear 70 rotates, the eccentric portion 12a of the crankshaft 12 rotates about the rotation center line passing through the crankshaft 12, and the external gear 14 oscillates through this eccentric portion 12a. As the external gear 14 oscillates, the meshing position of the external gear 14 and the outer pin 17 of the internal gear 16 shifts sequentially. As a result, each rotation of the crankshaft 12 generates a rotation of either the external gear 14 or the internal gear 16 equal to the difference between the number of teeth on the external gear 14 and the number of outer pins 17 on the internal gear 16. In this embodiment, the external gear 14 rotates, outputting decelerated rotation from the first bracket 18.

[0046] The features of the eccentric oscillating type speed reducer 10 configured as described above will be explained. The eccentric oscillating type speed reducer 10 includes an external gear 14, an internal gear 16 meshing with the external gear 14, and a first bracket 18 and a second bracket 20 disposed on the side of the external gear 14. The first bracket 18 is connected to the second bracket 20 via a connecting leg 5 fixed to it. The connecting leg 5 passes through the external gear 14 axially in a non-contact manner. The second bracket 20 has a positioning portion 4 for positioning the connecting leg 5 in the circumferential direction.

[0047] According to this structure, the connecting leg 5 is positioned by the positioning part 4. Therefore, there is no need to provide space for a limit pin on the connecting leg 5. Thus, the size or number of connecting bolts can be increased to improve the connection strength between the first bracket 18 and the second bracket 20. This allows torque transmission capability to be easily ensured between the first bracket 18 and the second bracket 20. Since there is no need to provide space for a limit pin on the connecting leg 5, the size of the connecting leg 5 can be correspondingly reduced, which is beneficial for miniaturization of the eccentric oscillating type speed reducer 10. Furthermore, since there is no need to provide a hole for a limit pin on the connecting leg 5, the strength of the connecting leg 5 is correspondingly improved. And since there is no need to provide a limit pin on the connecting leg 5, production efficiency is correspondingly improved.

[0048] As an example, the positioning part 4 includes a protrusion 42 that protrudes relative to the connecting foot 5. At this time, the protrusion 42 is brought into contact with the connecting foot 5, thereby limiting its movement.

[0049] As an example, the positioning part 4 includes a recess 44 for receiving the connecting foot 5. In this case, by receiving the connecting foot 5 in the recess 44, temporary positioning can be achieved, which is advantageous in terms of production efficiency.

[0050] As an example, the positioning part 4 positions the connecting foot 5 by bringing the outer periphery 56 of the connecting foot 5 into contact with the recess 44. At this time, by bringing the recess 44 into contact with the connecting foot 5, it is possible to limit its movement.

[0051] As an example, the recess 44 of the positioning part 4 has a circular shape with a portion of its outer periphery cut off, which is different from the shape of the outer contour of the connecting foot 5. At this time, since the recess 44 is a circular shape with a portion of its outer periphery cut off, the shape is simple and easy to process, and by managing the diameter, roundness, center coordinates, etc. of the circle, precision management can be achieved, which helps to reduce management time.

[0052] Here, the reason for notching open a portion of the outer periphery of the recess 44 will be explained. Considering the torque or strength of the connecting leg 5, a triangular prism shape with a large radius (R) at the radially thicker corner of the connecting leg 5 is advantageous. That is, this is because, in machining, it is easier to machine the outer periphery of the triangular prism shape with the large R into a circle centered on the central axis of the reducer. In this case, by making the recess 44 circular, and with the circumferential portion of the triangular prism shape with the large R contacting the inner periphery of the recess 44, it ultimately becomes a shape with an open outer periphery, thus making machining easier compared to the case where the outer periphery of the recess 44 is not notched.

[0053] As an example, in the positioning part 4, the outer periphery 56 of the connecting foot 5 contacts the recess 44 at multiple points, and the outline of the portion of the connecting foot 5 that is accommodated in the recess 44 is non-circular. In this case, since the part requiring machining accuracy can be limited to the contact points of the connecting foot 5, manufacturing becomes easier compared to ensuring overall machining accuracy.

[0054] As an example, in the positioning part 4, the portion of the connecting foot 5 that contacts the recess 44 is a machined surface 58. In this case, by making this portion a machined surface 58, the positioning accuracy can be improved compared to making it a non-machined surface.

[0055] The embodiments of the present invention have been described in detail above. The foregoing embodiments are merely specific examples of implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention; various design changes, such as alterations, additions, and deletions of constituent elements, can be made without departing from the inventive concept specified in the technical solution. In the foregoing embodiments, the content on which such design changes can be made is described with the addition of terms such as "in the embodiment" or "in the embodiment," but this does not mean that design changes are not prohibited for content without such descriptions. Furthermore, the shaded lines marked on the cross-sections of the accompanying drawings do not limit the material of the objects marked with shaded lines.

[0056] The following describes modified examples. In the accompanying drawings and descriptions of the modified examples, the same reference numerals are used to denote the same or equivalent components and parts as in the embodiment. Descriptions that are repeated in the embodiment are omitted where appropriate, and the focus is on describing structures that differ from the embodiment.

[0057] [Variation Example]

[0058] In the above description, an example is shown where the connecting leg 5 is integrally formed with the first bracket 18, but the present invention is not limited thereto. For example, the connecting leg may be formed as a different component from the first bracket and fixed to the first bracket by a fixing method such as threading or welding.

[0059] In the above description, an example of two bolts being used for connecting to the second bracket 20 is shown for one connecting leg 5, but the invention is not limited to this. The number of bolts can be one or more. From a production efficiency point of view, the number of bolts is preferably five or less.

[0060] In the above description, an example of a through hole 20j in the central hole 20j of the second bracket 20 is shown, but the invention is not limited thereto. The central hole 20j can be a non-through hole that is blocked on the input side. For example, the central hole 20j can be a recessed portion axially recessed from the input side of the second bracket 20.

[0061] In the above description, the number of crankshaft 12 and input gear 70 is set to 3, but the present invention is not limited to this. The number of crankshaft 12 and input gear 70 can be 1, 2 or more.

[0062] In the above description, an example with two external gears 14 was shown, but the present invention is not limited thereto. Three or more external gears 14 may be provided. For example, three eccentric portions 12a with their phases offset from each other by 120° may be provided on the crankshaft, and three external gears 14 may be provided that are oscillating by the three eccentric portions 12a. Furthermore, there may be only one external gear 14.

[0063] In the above description, an example is shown where the second main bearing 26 and the first main bearing 24 do not have inner rings, but the present invention is not limited thereto. One or both of the second main bearing 26 and the first main bearing 24 may be bearings with inner rings.

[0064] The above-described variations have the same function and effect as the above-described embodiments.

[0065] Any combination of the above-described embodiments and modifications is also effective as an embodiment of the present invention. New embodiments resulting from combinations possess the effects of each of the combined embodiments and modifications.

Claims

1. An eccentric oscillating type speed reduction device, comprising an external gear, an internal gear meshing with the external gear, and a first bracket and a second bracket disposed on the side of the external gear, wherein, The first bracket is connected to the second bracket via a connecting leg fixed to the first bracket. The connecting leg passes through the external gear axially in a non-contact manner. The second bracket has a positioning part for positioning the connecting foot in the circumferential direction.

2. The eccentric oscillating type speed reduction device according to claim 1, wherein, The positioning part includes a protrusion that protrudes relative to the connecting foot.

3. The eccentric oscillating type speed reduction device according to claim 1, wherein, The positioning part includes a recess for accommodating the connecting foot.

4. The eccentric oscillating type speed reduction device according to claim 3, wherein, The positioning part positions the connecting foot by contacting the recess with the outer periphery of the connecting foot.

5. The eccentric swing-type speed reduction device according to claim 4, wherein, In the positioning part, the outer periphery of the connecting foot contacts the recess at multiple points. The outer contour of the portion of the connecting foot that is accommodated in the recess is non-circular.

6. The eccentric oscillating type speed reduction device according to claim 4, wherein, In the positioning part, the part of the connecting foot that contacts the recess is a machined surface.

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