Eccentric swing type reduction gear

Abstract

One of the purposes of the present invention is to provide an eccentric oscillating speed reducer capable of improving the lubricity of an eccentric bearing. The eccentric oscillating speed reducer (100) comprises: an external gear; an eccentric shaft (12) for causing the external gear to oscillate eccentrically; and an eccentric bearing (30) disposed between the external gear and the eccentric shaft (12), wherein axial movement of the eccentric bearing (30) is restricted by a pressing portion (40), the pressing portion (40) comprising a cylindrical portion (402) extending in the axial direction and a flange portion (404) extending in the radial direction of the cylindrical portion (402).

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2021-035065, filed on March 5, 2021. The entire contents of this Japanese application are incorporated herein by reference. Technical Field

[0002] The invention relates to an eccentric swing type speed reducer. Background Art

[0003] An eccentric oscillating reduction gear equipped with an eccentric bearing is known. Patent Document 1, filed by the present applicant, discloses an oscillating internal meshing planetary gear mechanism comprising an external gear meshing with an internal gear, wherein an eccentric formed on an eccentric shaft causes one of the external and internal gears to oscillate. This gear mechanism includes an eccentric shaft bearing that supports the eccentric shaft.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-285396

[0005] The present inventors have studied an eccentric oscillating type speed reducer and have obtained the following findings.

[0006] In order to ensure the reliability of the eccentric bearing disposed between the external gear and the eccentric shaft of the reduction gear, it is important to stably supply lubricant to the eccentric bearing to improve lubricity. However, the reduction gear of Patent Document 1 does not fully address these issues and there is still room for improvement. Summary of the Invention

[0007] The present invention has been made in view of the above circumstances, and one object of the present invention is to provide an eccentric oscillating type reduction gear transmission capable of improving the lubricity of an eccentric bearing.

[0008] In order to solve the above-mentioned problems, an eccentric swing type reduction device of one embodiment of the present invention comprises: an external gear; an eccentric body shaft, which causes the external gear to swing eccentrically; and an eccentric body bearing, which is arranged between the external gear and the eccentric body shaft, wherein the axial movement of the eccentric body bearing is limited by a pressing portion, and the pressing portion has a cylindrical portion extending axially and a flange portion extending radially along the cylindrical portion.

[0009] According to the present invention, an eccentric oscillating type reduction gear transmission capable of improving the lubricity of an eccentric body bearing is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a side sectional view showing an eccentric oscillating type reduction gear transmission according to the embodiment.

[0011] Figure 2 yes Figure 1 A cross-sectional view of the eccentric swing type reduction gear device taken along line AA.

[0012] Figure 3 It is an enlarged representation Figure 1 A cross-sectional view of the periphery of the eccentric body shaft.

[0013] Figure 4 It is an enlarged representation Figure 3 A cross-sectional view of the periphery of the pressing portion.

[0014] Figure 5 It is an enlarged representation Figure 3 A cross-sectional view of the periphery of the pressing portion.

[0015] In the figure: 12-eccentric body shaft, 14-external gear, 30-eccentric body bearing, 40-pressing portion, 124-concave portion, 126-convex portion, 128-eccentric portion, 129, 130, 131-outer periphery, 304-retaining frame, 306-annular portion, 308-outer periphery, 335-outer periphery, 402-cylindrical portion, 404-flange portion, 406-abutment portion, 407, 408-outer periphery, W1, W2, W3-axial dimension, 100-eccentric swing type reduction gear. DETAILED DESCRIPTION

[0016] Preferred embodiments of the present invention are described below with reference to the accompanying drawings. In the embodiments and variations, identical or equivalent components and parts are denoted by the same reference numerals, and duplicate descriptions are omitted where appropriate. Furthermore, in the drawings, the dimensions of the components are exaggerated or reduced as appropriate to facilitate understanding. Furthermore, in the drawings, some components not essential to the description of the embodiments are omitted.

[0017] Furthermore, terms including numbers such as 1 and 2 are used to describe various constituent elements, but such terms are only used to distinguish one constituent element from other constituent elements and are not used to limit the constituent elements.

[0018] [Implementation Method]

[0019] Hereinafter, the structure of an eccentric oscillating speed reduction gear 100 (hereinafter sometimes referred to as “speed reduction gear 100 ”) according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 It is a side cross-sectional view schematically showing the reduction gear transmission 100 according to the present embodiment. Figure 2 It is along Figure 1 Cross-sectional view taken along line AA. Figure 3 It is a cross-sectional view showing an enlarged view of the periphery of the eccentric body shaft 12. The application of the reduction gear 100 is not limited. In this example, the reduction gear 100 can be used for joints of a multi-joint robot, for example.

[0020] Next, the overall structure of the reduction gear 100 will be described. The reduction gear 100 mainly includes an eccentric shaft 12, an external gear 14, an internal gear 16, carriers 18 and 20, a housing 22, main bearings 24 and 26, an eccentric bearing 30, an inner pin 32, eccentric shaft bearings 33 and 34, and a pressing portion 40.

[0021] Hereinafter, the direction along the center axis La of the internal gear 16 will be referred to as the "axial direction," and the circumferential and radial directions of a circle centered on the center axis La will be referred to as the "circumferential direction" and the "radial direction," respectively. Furthermore, for convenience, the axially directed side (the right side in the figure) will be referred to as the input side, and the axially directed side (the left side in the figure) will be referred to as the counter-input side. These directional designations do not limit the operating position of the reduction gear 100; the reduction gear 100 can be used in any position.

[0022] The wheel carriers 18 and 20 include a first wheel carrier 18 arranged on the opposite side of the input of the external gear 14 and a second wheel carrier 20 arranged on the input side of the external gear 14. The main bearings 24 and 26 include a first main bearing 24 arranged on the opposite side of the input of the external gear 14 and a second main bearing 26 arranged on the input side of the external gear 14. The eccentric body shaft bearings 33 and 34 include a first eccentric body shaft bearing 33 arranged on the opposite side of the input of the external gear 14 and a second eccentric body shaft bearing 34 arranged on the input side of the external gear 14.

[0023] The reduction gear 100 of this embodiment is a center crank type reduction gear in which the eccentric shaft 12 is coaxial with the center axis La of the internal gear 16. The reduction gear 100 has a hollow portion H extending axially through the center. The hollow portion H is provided in the eccentric shaft 12.

[0024] The housing 22 forms the outer shell of the reduction gear 100. The wheel carriers 18 and 20 are arranged inside the housing 22 and rotate relative to the housing 22. The eccentric shaft 12 has a hollow cylindrical shape with a hollow portion H at the center. For example, a motor shaft is connected to the input-side end of the eccentric shaft 12 via a fastener such as a bolt.

[0025] The eccentric body shaft 12 has a plurality of eccentric portions 128, which function as eccentric bodies that cause the external gear 14 to swing. In this example, the eccentric body shaft 12 has two eccentric portions 128 that are 180 degrees out of phase with each other. The two ends of the eccentric body shaft 12 are supported on the wheel frames 18 and 20 via eccentric body shaft bearings 33 and 34. In addition, the number of eccentric portions 128 is not limited to two, and can also be one or more than three.

[0026] like Figure 3As shown, the eccentric shaft 12 has a radially inwardly recessed recess 124 near the side opposite the input of the eccentric bearing 30. Furthermore, the eccentric shaft 12 has a radially outwardly protruding projection 126 adjacent to the recess 124 on the side opposite the eccentric bearing 30. The recess 124 and projection 126 will be described later. Lubricant G is enclosed inside the housing 22 (particularly near the eccentric bearing 30).

[0027] The structure of the eccentric shaft bearings 33 and 34 is not limited. In this example, the first eccentric shaft bearing 33, which is located on the opposite side of the input, is a deep groove ball bearing whose rolling elements 332 are balls (spherical balls). The rolling elements 332 roll between the inner ring 334 and the outer ring 336. The second eccentric shaft bearing 34, which is located on the input side, is a roller bearing whose rolling elements 342 are rollers (cylindrical balls). The second eccentric shaft bearing 34 does not have an inner ring or an outer ring, and the rolling elements 342 roll between the outer peripheral surface 132 of the eccentric shaft 12 and the inner peripheral surface 202 of the second wheel carrier 20.

[0028] In this embodiment, the eccentric bearing 30 has a rolling element 302 in the shape of a cylindrical roller and a retaining frame 304. A plurality of (for example, 38) rolling elements 302 are arranged at predetermined intervals around the eccentric portion 128. The retaining frame 304 rotatably retains the plurality of rolling elements 302 in a predetermined position. The retaining frame 304 has an annular ring portion 306 provided on the side of the axial ends of the rolling element 302 and a bag-shaped portion (not shown) for accommodating the rolling element 302. The eccentric bearing 30 does not have an inner ring and an outer ring, and the rolling element 302 rolls between the outer peripheral surface of the eccentric portion 128 and the inner peripheral surface of the center hole 14c of the external gear 14. As shown in FIG. Figure 3 As shown, the pressing portion 40 restricts the eccentric bearing 30 from moving toward the opposite input side in the axial direction. The retaining ring 352 and the washer 354 restrict the eccentric bearing 30 from moving toward the input side in the axial direction via the second eccentric shaft bearing 34. The pressing portion 40 will be described later.

[0029] like Figure 2 As shown, the external gear 14 is rotatably supported by the corresponding eccentric portion 128 via the eccentric body bearing 30. A center hole 14c and a plurality of inner pin holes 14h are formed on the external gear 14. The center hole 14c is a through hole set at the center of the external gear 14. The plurality of inner pin holes 14h are through holes set at positions deviated from the center of the external gear 14. Figure 2 In the example shown, ten inner pin holes 14h are arranged at 36° intervals in the circumferential direction. Inner pins 32 are inserted through inner pin holes 14h. The teeth formed on the outer circumference of external gear 14 mesh with the teeth of internal gear 16 while rotating, causing external gear 14 to oscillate.

[0030] like Figure 2As shown, the internal gear 16 meshes with the external gear 14. In this embodiment, the internal gear 16 comprises an internal gear body integral with the housing 22 and outer pins 16p (pin members) rotatably supported by the internal gear body. The outer pins 16p form 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 greater than the number of external teeth of the external gear 14 (in this example, only one more).

[0031] like Figure 1 As shown, the first carrier 18 and the second carrier 20 are rotatably supported by the housing 22 via the main bearings 24 and 26. The first carrier 18 supports the eccentric shaft 12 via the first eccentric shaft bearing 33. The second carrier 20 supports the eccentric shaft 12 via the second eccentric shaft bearing 34.

[0032] The first carrier 18 and the second carrier 20 are connected via inner pins 32. The inner pins 32 extend through inner pin holes 14h of the external gear 14 in the axial direction at positions offset in the radial direction from the axis of the external gear 14.

[0033] One of the wheel carriers 18, 20 and the housing 22 functions as an output member that outputs rotational power to the driven device, while the other functions as a fixed member fixed to an external member that supports the reduction gear 100. In this embodiment, the output members are the first wheel carrier 18 and the second wheel carrier 20, and the fixed member is the housing 22.

[0034] exist Figure 2 In the example of , 10 inner pins 32 are arranged at 36° intervals in the circumferential direction. Figure 1 In FIG, only one inner pin 32 is shown. The opposite side of the input of the inner pin 32 is fixed to the first wheel frame 18, and the input side is fixed to the second wheel frame 20. The inner pin 32 connects the first wheel frame 18 and the second wheel frame 20. Figure 1 In the example shown, the inner pin 32 is integrally formed with the first wheel carrier 18, with the input side secured to the second wheel carrier 20 by bolts B1. A sleeve 32s is provided around the outer periphery of the inner pin 32. The inner pin 32 is inserted through the inner pin hole 14h with a gap between the inner pin 32 and the inner pin hole 14h. The inner pin 32 abuts a portion of the inner pin hole 14h via the sleeve 32s. The inner pin 32 restricts the rotation of the external gear 14, allowing only its swinging motion.

[0035] The main bearings 24 and 26 are arranged between the first wheel carrier 18 and the housing 22 and between the second wheel carrier 20 and the housing 22. The structure of the main bearings 24 and 26 is not limited. In this example, the main bearings 24 and 26 are roller bearings whose rolling elements 24e and 26e are cylindrical rollers. Figure 1The retainer holding the rolling elements 24e and 26e is omitted. The outer rings of the main bearings 24 and 26 are supported by the housing 22. The inner ring of the first main bearing 24 is integrally formed with the wheel carrier 18. The inner ring of the second main bearing 26 is integrally formed with the wheel carrier 20.

[0036] The housing 22 is a hollow cylindrical member surrounding the wheel carriers 18 and 20. Figure 1 As shown, an oil seal 28 for sealing lubricant from the main bearing 24 is provided between the housing 22 and the first carrier 18 .

[0037] Hereinafter, the characteristic structure of this embodiment will be described.

[0038] The present inventors have studied the reduction gear transmission and, as a result, have obtained the following findings.

[0039] In order to achieve miniaturization and lightweighting of the reduction gear, it is necessary to miniaturize the rolling elements of the eccentric bearing disposed between the external gear and the eccentric shaft. For example, when the reduction gear 100 is applied to a joint of a robot, etc., it is preferable to increase the hollow diameter of the hollow portion H of the eccentric shaft 12 in order to allow wiring or piping to pass through. In order to increase the hollow diameter without changing the overall size, it is possible to consider reducing the roller diameter of the roller (rolling element 302) of the eccentric bearing 30. However, if the roller diameter is reduced, the life of the bearing tends to be shortened.

[0040] To reduce the roller diameter while ensuring bearing life, improving lubricity is effective. To improve lubricity, filling the interior of the reduction gear with lubricant is a possible approach. In this case, the area surrounding the high-speed rotating eccentric shaft 12 is filled with lubricant, increasing the lubricant's stirring resistance and leading to increased losses. Furthermore, if the lubricant filling level is reduced, the centrifugal force during rotation will cause the lubricant to be biased toward the outer circumference, reducing the amount of lubricant available to lubricate the rolling elements 302 and shortening their lifespan.

[0041] Based on this, the inventors have conducted extensive research to create a lubricant storage space around rolling element 302. They discovered that by pressing rolling element 302 with a pressing portion of a predetermined shape, a lubricant storage space can be secured near rolling element 302. This structure can suppress increases in the lubricant's stirring resistance while also reducing the effects of centrifugal force. This is described in detail below.

[0042] refer to Figures 3 to 5 The pressing portion 40 will be described. Figure 4 and Figure 5 It is a cross-sectional view showing an enlarged view of the periphery of the pressing portion 40 (the range of the dotted line E). Figure 5 The eccentric body shaft 12 is shown relative to Figure 4The pressing portion 40 is configured to restrict the eccentric bearing 30 from moving toward the opposite input side in the axial direction and to ensure a storage space for the lubricant G around the rolling element 302, thereby reducing the escape of the lubricant G caused by centrifugal force.

[0043] like Figures 3 to 5 As shown, the pressing portion 40 includes a cylindrical portion 402, a flange portion 404, and an abutting portion 406. The pressing portion 40 is a hollow annular member made of metal or resin. The cylindrical portion 402, flange portion 404, and abutting portion 406 of the pressing portion 40 can be uniform in the circumferential direction and have no holes, protrusions, or recesses, or they can be non-uniform in the circumferential direction and have holes, protrusions, or recesses on a portion of the circumference.

[0044] The cylindrical portion 402 is a cylindrical portion extending in the axial direction, and its outer diameter can be constant in the axial direction or can vary in the axial direction. The flange portion 404 is a flange-shaped portion extending in the radial direction of the cylindrical portion 402. In this example, the flange portion 404 extends radially outward from the end portion of the input side of the cylindrical portion 402. When viewed from the axial direction, the outer shape of the flange portion 404 can be circular or non-circular. Figures 3 to 5 As shown, the flange portion 404 abuts against the opposite-input side of the annular portion 306 of the retainer 304 of the eccentric bearing 30 .

[0045] The abutment portion 406 is a portion that limits the axial movement of the pressing portion 40. In this example, the abutment portion 406 is provided on the side of the cylindrical portion 402 opposite to the flange portion 404 (the opposite input side), and extends radially inward from the end of the cylindrical portion 402. When viewed from the axial direction, the inner shape of the abutment portion 406 can be circular or non-circular. Figures 3 to 5 As shown, the contact portion 406 is inserted into the axial gap between the protrusion 126 of the eccentric shaft 12 and the inner ring 334 of the first eccentric shaft bearing 33. The contact portion 406 contacts the inner ring 334 of the first eccentric shaft bearing 33.

[0046] like Figure 3 As shown, the eccentric body shaft 12 has an outer peripheral surface 132 that is fitted with the second eccentric body shaft bearing 34 and an outer peripheral surface 133 for setting the first eccentric body shaft bearing 33. The direction in which the eccentric portion 128 in the radial direction of the eccentric body shaft 12 is eccentric to the outermost side is called the maximum eccentric direction, and the direction in which the eccentric portion 128 is eccentric to the opposite side is called the maximum counter-eccentric direction. Figure 4 and Figure 5In the figure, eccentric portion 128-A of eccentric body shaft 12 indicates the direction of maximum eccentricity, and eccentric portion 128-B indicates the direction of maximum counter-eccentricity. Reference numeral 129 denotes the outer periphery of eccentric portion 128-A in the direction of maximum eccentricity, and reference numeral 130 denotes the outer periphery of eccentric portion 128-B in the direction of maximum counter-eccentricity. Outer periphery line A is a line extending axially from the outer periphery of eccentric portion 128-A in the direction of maximum eccentricity, and outer periphery line B is a line extending axially from the outer periphery of eccentric portion 128-B in the direction of maximum counter-eccentricity.

[0047] In this embodiment, the axial movement of the eccentric bearing 30 is restricted by the pressing portion 40, which includes a cylindrical portion 402 extending in the axial direction and a flange portion 404 extending in the radial direction of the cylindrical portion 402. In this case, the lubricant G can be stored in the inner space of the cylindrical portion 402.

[0048] To ensure sufficient storage space for the lubricant G around the rolling elements 302, the cylindrical portion 402 preferably has a larger axial dimension W1. Therefore, in this embodiment, the axial dimension W1 of the cylindrical portion 402 is larger than the axial dimension W2 of the annular portion 306 of the retainer 304 of the eccentric bearing 30. This allows for greater storage space for the lubricant G while maintaining a constant overall axial dimension.

[0049] Similarly, to ensure storage space for the lubricant G, in this embodiment, the axial dimension W1 of the cylindrical portion 402 is larger than the axial dimension W3 of the flange portion 404. In this case, the storage space for the lubricant G can be expanded while keeping the total axial dimension of the pressing portion 40 constant.

[0050] Similarly, to ensure sufficient storage space for the lubricant G, in this embodiment, the eccentric shaft 12 includes a radially inwardly recessed recess 124 at a location where it overlaps with the pressing portion 40 when viewed radially. The recess 124 increases the storage space for the lubricant G. Furthermore, the recess 124 may be radially opposed to (overlapping with) the annular portion 306 of the retainer 304. In this case, the lubricant G in the recess 124 easily entangles with the eccentric bearing 30, thereby improving lubricity.

[0051] If the recess 124 is away from the storage space for the lubricant G, the lubricant G in the recess 124 is less likely to entangle with the eccentric bearing 30. Therefore, in this embodiment, when viewed from the radial direction, the recess 124 overlaps (radially opposes) the flange portion 404. In this case, the lubricant G in the recess 124 effectively contributes to the lubrication of the eccentric bearing 30.

[0052] If the lubricant G within the recess 124 escapes to the side opposite the input, it will be detrimental to the lubrication of the eccentric bearing 30. Therefore, in this embodiment, the eccentric shaft 12 has a radially outwardly projecting convex portion 126 at a position adjacent to the side of the recess 124 opposite the eccentric bearing 30. This can block the lubricant G within the recess 124, thereby reducing its escape toward the side opposite the input. In this embodiment, the axial dimensions of the recess 124 and the convex portion 126 are substantially the same.

[0053] If the positional relationship between the pressing portion 40 and the recessed portion 124 is unstable, the lubricity-enhancing effect of the eccentric body bearing 30 based on the lubricant G in the recessed portion 124 will become unstable. Therefore, in this embodiment, the pressing portion 40 has an abutment portion 406 provided on the side of the cylindrical portion 402 opposite the flange portion 404, which abuts against the convex portion 126 to restrict the axial movement of the pressing portion 40. In this case, by axially aligning the convex portion 126 with the abutment portion 406, the position of the pressing portion 40 relative to the eccentric body shaft 12 can be stabilized, thereby stabilizing the lubricity-enhancing effect based on the lubricant G. The abutment portion 406 is present in the axial gap between the inner ring 334 of the first eccentric body shaft bearing 33 and the convex portion 126, and abuts against both in the axial direction.

[0054] From the viewpoint of ensuring storage space for the lubricant G, in this embodiment, Figure 4 As shown, in the direction of maximum eccentricity of the eccentric body shaft 12, the outer periphery 407 of the cylindrical portion 402 is located radially outward relative to the outer periphery 129 of the eccentric portion 128 of the eccentric body shaft 12. By increasing the outer periphery 407, it is possible to increase the storage space for the lubricant G. In this embodiment, in the direction of maximum eccentricity of the eccentric body shaft 12, the entire axial range of the outer periphery 407 of the cylindrical portion 402 is located radially outward relative to the eccentric portion 128.

[0055] Furthermore, in this embodiment, the outer periphery 407 of the cylindrical portion 402 is located radially inward of the outer periphery 335 of the inner ring 334 of the first eccentric shaft bearing 33. In other words, the outer diameter of the outer periphery 407 is smaller than the outer diameter of the outer periphery 335. This reduces the possibility of the pressing portion 40 interfering with the retainer (not shown) of the first eccentric shaft bearing 33.

[0056] Furthermore, in this embodiment, Figure 5 As shown, in the maximum anti-eccentric direction of the eccentric body shaft 12, the outer periphery 130 (outer periphery line B) of the eccentric portion 128 of the eccentric body shaft 12 is located radially inward of the outer periphery 131 of the convex portion 126. Figure 4As shown, in the maximum eccentricity direction of the eccentric body shaft 12 , the outer periphery 129 (outer periphery line A) of the eccentric portion 128 of the eccentric body shaft 12 is located radially outward of the outer periphery 131 of the convex portion 126 .

[0057] Furthermore, in this embodiment, Figure 4 and Figure 5 As shown, the cylindrical portion 402 has a shape whose diameter increases axially toward the eccentric bearing 30, and the outer circumferential contour line is inclined relative to the axial direction. The cylindrical portion 402 may have a conical shape, for example, and the outer circumferential contour line may be a straight line or a curved line. In this case, by increasing the diameter toward the eccentric bearing 30, the storage space for the lubricant G can be increased compared to a case where the diameter toward the eccentric bearing 30 is small.

[0058] Furthermore, in this embodiment, Figure 4 As shown, in the direction of maximum eccentricity of the eccentric body shaft 12, the outer periphery 408 of the flange portion 404 is located radially outward from the outer periphery 308 of the retainer 304. At this time, the outer periphery 408 of the flange portion 404 blocks the lubricant G near the retainer 304, thereby reducing the escape of the lubricant G.

[0059] Furthermore, in this embodiment, Figure 5 As shown, in the direction of maximum counter-eccentricity of the eccentric body shaft 12, the inner periphery 409 of the flange portion 404 is located radially inwardly of the outer periphery 308 of the retainer 304. In this case, the contact area between the flange portion 404 and the annular portion 306 of the retainer 304 can be ensured, thereby reducing the possibility of the retainer 304 falling off during the manufacturing process.

[0060] Next, the operation of the reduction gear 100 constructed in this manner will be described. If rotation is transmitted from the motor to the eccentric body shaft 12, the eccentric portion 128 of the eccentric body shaft 12 rotates around the rotation center line passing through the eccentric body shaft 12, and the external gear 14 swings via the eccentric body bearing 30. If the external gear 14 swings, the meshing positions of the external gear 14 and the internal gear 16 are sequentially offset. As a result, for each rotation of the eccentric body shaft 12, one of the external gear 14 and the internal gear 16 rotates by an amount equivalent 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 the reduced rotation is output from the first wheel frame 18 and the second wheel frame 20 via the inner pin 32.

[0061] Next, the features of the thus constructed reduction gear 100 will be described. The reduction gear 100 comprises an external gear 14; an eccentric shaft 12 for eccentrically oscillating the external gear 14; and an eccentric bearing 30 disposed between the external gear 14 and the eccentric shaft 12. Axial movement of the eccentric bearing 30 is restricted by a pressing portion 40, which comprises an axially extending cylindrical portion 402 and a radially extending flange portion 404.

[0062] With this structure, the pressing portion 40 ensures a space for retaining lubricant near the rolling element 302. Furthermore, this structure suppresses an increase in stirring resistance of the lubricant G and reduces the influence of centrifugal force. Consequently, the lubricity of the eccentric bearing 30 can be improved.

[0063] The examples of the embodiments of the present invention have been described in detail above. The above embodiments are merely specific examples for implementing the present invention. The contents of the embodiments are not intended to limit the technical scope of the present invention, and various design changes such as changes, additions, and deletions of constituent elements can be made without departing from the scope of the inventive concept specified in the technical solution. In the above embodiments, the contents that can make such design changes are explained with phrases such as "embodiment" and "in the embodiment", but this does not mean that design changes are not allowed without the contents of such phrases. In addition, in the accompanying drawings, the hatching lines marked on the cross-sections are not used to limit the material of the objects marked with hatching lines.

[0064] The following describes a modified example. In the drawings and descriptions of the modified example, the same or equivalent components and parts as those in the embodiment are marked with the same reference numerals. Explanations that overlap with the embodiment are omitted as appropriate, and the focus is on the structures that differ from the embodiment.

[0065] [Modification]

[0066] While the embodiment describes an example of a center crank type eccentric oscillating speed reduction gear 100, the present invention is not limited thereto. The type of speed reduction mechanism is not particularly limited, as long as the speed reduction gear has an eccentric bearing disposed between the external gear and the eccentric shaft. For example, a so-called distributed eccentric oscillating speed reduction gear in which multiple crankshafts are disposed at positions offset from the center may also be employed.

[0067] In the description of the embodiment, an example in which the number of the external gears 14 is two is shown, but the number of the external gears may be one or three or more.

[0068] In the description of the embodiment, an example is shown in which the pin member for connecting the carriers 18 and 20 includes the inner pin 32 that helps transmit the driving force of the external gear 14. The pin member for connecting the carriers 18 and 20 may also include a carrier pin that is different from the inner pin 32 and does not contribute to the transmission of the driving force.

[0069] In the description of the embodiment, an example is shown in which the inner pins 32 are formed integrally with the first carrier 18 . However, the inner pins 32 may be formed separately from the first carrier 18 and connected with a fastener such as a bolt.

[0070] In the description of the embodiment, an example is shown in which the eccentric bearing 30 does not include an inner ring and an outer ring. However, the eccentric bearing 30 may include an inner ring or an outer ring.

[0071] In the description of the embodiment, an example is shown in which the inner rings of the main bearings 24 and 26 are formed integrally with the carriers 18 and 20 , but the inner rings of the main bearings may be formed separately from the carriers.

[0072] In the description of the embodiment, an example is shown in which the rolling elements 24e and 26e of the main bearings 24 and 26 are cylindrical rollers, but the rolling elements of the main bearings may also have a shape different from the cylindrical rollers, such as tapered rollers or spheres. Furthermore, the main bearings are not limited to those composed of a pair of bearings, and may also be, for example, cross-roller bearings. In the description of the embodiment, an example is shown in which the rolling elements 332 of the eccentric shaft bearings 33 and 34 are spheres, but the rolling elements of the eccentric shaft bearings may also have a shape different from the spheres (for example, a cylindrical roller shape, etc.). In the description of the embodiment, an example is shown in which the rolling elements 302 of the eccentric bearing 30 are cylindrical rollers, but the rolling elements of the eccentric bearings may also have a shape different from the cylindrical rollers (for example, a sphere, etc.).

[0073] In the description of the embodiment, the example in which the convex portion 126 of the eccentric shaft 12 is arranged adjacent to the concave portion 124 is shown as an adjacent example. However, a flat portion or the like may be provided between the convex portion and the concave portion of the eccentric shaft.

[0074] In the description of the embodiment, as an example in which the entire axial range of the outer periphery 407 of the cylindrical portion 402 in the direction of the maximum eccentricity of the eccentric body shaft 12 is located radially outward than the eccentric portion 128, an example is shown in which the entire axial range of the outer periphery 407 of the cylindrical portion 402 in the direction of the maximum eccentricity of the eccentric body shaft 12 is located radially outward than the eccentric portion 128. However, the structure in which the structure in which the structure is located radially outward than the eccentric portion 128 may also be a structure in which a part of the axial range of the outer periphery of the cylindrical portion is located radially outward than the eccentric portion.

[0075] The above-mentioned modifications also have the same functions and effects as those of the embodiment.

[0076] Any combination of the constituent elements and modifications of the above-described embodiments is also effective as an embodiment of the present invention. New embodiments generated by the combination have the effects of the combined embodiments and modifications.

Claims

1. An eccentric swing type reduction gear device, comprising: External gear; An eccentric body shaft causes the external gear to oscillate eccentrically; and The eccentric bearing is arranged between the external gear and the eccentric shaft. The eccentric oscillating type reduction gear is characterized in that: The axial movement of the eccentric bearing is restricted by the pressing portion. The pressing portion includes a cylindrical portion extending in the axial direction and a flange portion extending in the radial direction of the cylindrical portion. The eccentric body shaft is provided with a restriction portion for restricting the movement of the pressing portion toward the eccentric body bearing side. The eccentric body shaft has a recessed portion between the restriction portion and the eccentric body bearing, the recessed portion being recessed radially inward relative to an outer shape of the restriction portion.

2. The eccentric oscillating speed reduction device according to claim 1, characterized in that: The axial dimension of the cylindrical portion is larger than the axial dimension of the annular portion of the retainer of the eccentric bearing.

3. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: The axial dimension of the cylindrical portion is larger than the axial dimension of the flange portion.

4. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: The recessed portion overlaps with the pressing portion when viewed in the radial direction.

5. The eccentric oscillating speed reduction device according to claim 4, characterized in that: When viewed in the radial direction, the recessed portion overlaps with the flange portion.

6. The eccentric oscillating speed reduction device according to claim 4, characterized in that: The eccentric body shaft has a convex portion protruding radially outward at a position adjacent to the concave portion on the opposite side to the eccentric body bearing.

7. The eccentric oscillating speed reduction device according to claim 1, wherein: The pressing portion includes an abutment portion provided on a side of the cylindrical portion opposite to the flange portion, and the abutment portion abuts against the restriction portion to restrict movement of the pressing portion in the axial direction.

8. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: In the maximum eccentricity direction of the eccentric body shaft, the outer periphery of the cylindrical portion is located radially outward of the outer periphery of the eccentric portion of the eccentric body shaft.

9. The eccentric oscillating speed reduction device according to claim 6, wherein: In the maximum anti-eccentricity direction of the eccentric body shaft, the outer periphery of the eccentric portion of the eccentric body shaft is located radially inward of the outer periphery of the convex portion.

10. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: The recessed portion overlaps with the eccentric bearing when viewed in the radial direction.

11. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: In the direction of maximum eccentricity of the eccentric body shaft, the outer periphery of the flange portion is located radially outward of the outer periphery of the retainer of the eccentric body bearing.

12. The eccentric oscillating speed reduction device according to claim 1 or 2, characterized in that: In the maximum counter-eccentricity direction of the eccentric body shaft, the inner periphery of the flange portion is located radially inward of the outer periphery of the retainer of the eccentric body bearing.

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