Eccentric swing type reduction gear

Abstract

To provide an eccentric oscillation speed reducer capable of improving lubrication of an eccentric body bearing.SOLUTION: An eccentric oscillation speed reducer 100 has an external gear, an eccentric body shaft 12 that eccentrically oscillates the external gear, and an eccentric body bearing 30 arranged between the external gear and the eccentric body shaft 12. The axial movement of the eccentric body bearing 30 is restricted by a pressing part 40. The pressing part 40 has a cylindrical part 402 extending axially, and a flange part 404 extending in a radial direction of the cylindrical part 402.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] An eccentric swing type reduction gear provided with an eccentric body bearing is known. The applicant has disclosed in Patent Document 1 a swing internal meshing planetary gear device having an external gear that internally meshes with an internal gear, and configured such that either the external gear or the internal gear is swing-rotated by an eccentric body formed on an eccentric body shaft. This gear device includes a bearing for the eccentric body shaft that supports the eccentric body shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor has studied an eccentric swing type reduction gear and obtained the following recognition. In order to ensure the reliability of the eccentric body bearing disposed between the external gear of the reduction gear and the eccentric body shaft, it is important to stably supply a lubricant to the eccentric body bearing to improve lubricity. However, the reduction gear of Patent Document 1 does not adequately address these viewpoints and there is room for improvement.

[0005] The present invention has been made in view of such circumstances, and one of its objects is to provide an eccentric swing type reduction gear capable of improving the lubricity of the eccentric body bearing.

Means for Solving the Problems

[0006] In order to solve the above problems, an eccentric swing type reduction gear according to an aspect of the present invention has an external gear, an eccentric body shaft for eccentrically swinging the external gear, and an eccentric body bearing disposed between the external gear and the eccentric body shaft. In the eccentric swing type reduction gear, the axial movement of the eccentric body bearing is restricted by a pressing portion, and the pressing portion has a cylindrical portion extending in the axial direction and a flange portion extending in the radial direction of the cylindrical portion.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide an eccentric swing type reduction gear that can improve the lubricity of the eccentric body bearing.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described with reference to the accompanying drawings based on preferred embodiments. In the embodiments and modification examples, the same or equivalent components and members are denoted by the same reference numerals, and repeated explanations are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. In each drawing, some members that are not important for explaining the embodiments are omitted.

[0010] In addition, terms including ordinals such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from another, and the components are not limited by this term.

[0011] [Embodiment] Hereinafter, with reference to the drawings, the configuration of an eccentric swing type speed reducer 100 (hereinafter sometimes referred to as "speed reducer 100") according to an embodiment of the present disclosure will be described. FIG. 1 is a side cross-sectional view schematically showing the speed reducer 100 of the present embodiment. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1. FIG. 3 is a cross-sectional view showing an enlarged periphery of the eccentric body shaft 12. Although there is no limitation on the use of the speed reducer 100, the speed reducer 100 in this example can be used, for example, in the joints of a multi-joint robot.

[0012] The overall configuration of the speed reducer 100 will be described. The speed reducer 100 mainly includes an eccentric body shaft 12, an external gear 14, an internal gear 16, carriers 18 and 20, a casing 22, main bearings 24 and 26, an eccentric body bearing 30, an inner pin 32, eccentric body shaft bearings 33 and 34, and a pressing portion 40.

[0013] Hereinafter, the direction along the central axis La of the internal gear 16 is referred to as the "axial direction", and the circumferential direction and the radial direction of a circle centered on the central axis La are referred to as the "circumferential direction" and the "radial direction", respectively. Also, hereinafter, for convenience, one side in the axial direction (the right side in the figure) is referred to as the input side, and the other side (the left side in the figure) is referred to as the anti-input side. Such notation of directions does not limit the use posture of the speed reducer 100, and the speed reducer 100 can be used in any posture.

[0014] The carriers 18 and 20 include a first carrier 18 disposed on the anti-input side of the external gear 14 and a second carrier 20 disposed on the input side of the external gear 14. The main bearings 24 and 26 include a first main bearing 24 disposed on the anti-input side of the external gear 14 and a second main bearing 26 disposed 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 disposed on the anti-input side of the external gear 14 and a second eccentric body shaft bearing 34 disposed on the input side of the external gear 14.

[0015] The speed reducer 100 of this embodiment is of the center crank type in which the eccentric shaft 12 is provided on the same axis as the central axis La of the internal gear 16. The speed reducer 100 has a hollow portion H that penetrates axially in the central portion. The hollow portion H is provided on the eccentric shaft 12.

[0016] The casing 22 constitutes the outer shell of the speed reducer 100. The carriers 18 and 20 are arranged inside the casing 22 and rotate relative to the casing 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 by a connector such as a bolt.

[0017] The eccentric shaft 12 has a plurality of eccentric portions 128 and functions as an eccentric body that swings the external gear 14. In this example, the eccentric shaft 12 has two eccentric portions 128 with a 180° phase shift. Both ends of the eccentric shaft 12 are supported by the carriers 18 and 20 via the eccentric shaft bearings 33 and 34. Note that the number of the eccentric portions 128 is not limited to two and may be one or three or more.

[0018] As shown in FIG. 3, the eccentric shaft 12 has a recess 124 that is recessed radially inward in the vicinity of the anti-input side of the eccentric shaft bearing 30. Further, the eccentric shaft 12 has a protrusion 126 that protrudes radially outward at a position adjacent to the side of the recess 124 opposite to the eccentric shaft bearing 30. The recess 124 and the protrusion 126 will be described later. A lubricant G is enclosed inside the casing 22, particularly in the vicinity of the eccentric shaft bearing 30.

[0019] There is no limitation on the configuration of the eccentric shaft bearings 33 and 34. In this example, the first eccentric shaft bearing 33 arranged on the anti-input side is a deep groove ball bearing in which the rolling elements 332 are balls (spheres). The rolling elements 332 roll between the inner ring 334 and the outer ring 336. The second eccentric shaft bearing 34 arranged on the input side is a roller bearing in which the rolling elements 342 are rollers (cylindrical bodies). The second eccentric shaft bearing 34 does not have an inner ring and 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 carrier 20.

[0020] In this embodiment, the eccentric bearing 30 has a cylindrical roller-shaped rolling element 302 and a retainer 304. A plurality (e.g., 38) of rolling elements 302 are arranged at predetermined intervals around the eccentric portion 128. The retainer 304 rotatably holds the plurality of rolling elements 302 in predetermined positions. The retainer 304 has an annular ring portion 306 provided on side portions at both axial ends of the rolling element 302 and a pocket (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 central hole 14c of the external gear 14. As shown in FIG. 3, the axial movement of the eccentric bearing 30 toward the non-input side is restricted by the pressing portion 40. The axial movement of the eccentric bearing 30 toward the input side is restricted via the second eccentric shaft bearing 34 by the retaining ring 352 and the washer 354. The pressing portion 40 will be described later.

[0021] As shown in FIG. 2, the external gear 14 is rotatably supported by the corresponding eccentric portion 128 via the eccentric bearing 30. The external gear 14 is formed with a central hole 14c and a plurality of inner pin holes 14h. The central hole 14c is a through hole provided at the center of the external gear 14. The plurality of inner pin holes 14h are through holes provided at positions offset from the center of the external gear 14. In the example of FIG. 2, ten inner pin holes 14h are arranged at 36° intervals in the circumferential direction. Inner pins 32 are inserted into the inner pin holes 14h. The teeth formed on the outer periphery of the external gear 14 rotate while meshing with the teeth of the internal gear 16, causing the external gear 14 to swing.

[0022] As shown in FIG. 2, the internal gear 16 meshes with the external gear 14. The internal gear 16 of this embodiment is composed of an internal gear main body integrated with the casing 22 and an external pin 16p (pin member) rotatably supported by the internal gear main body. The external pin 16p constitutes the internal teeth of the internal gear 16. The number of internal teeth of the internal gear 16 (the number of external pins 16p) is slightly (by 1 in this example) more than the number of external teeth of the external gear 14.

[0023] As shown in FIG. 1, the first carrier 18 and the second carrier 20 are rotatably supported by a casing 22 via main bearings 24 and 26. The first carrier 18 supports an eccentric shaft 12 via a first eccentric shaft bearing 33. The second carrier 20 supports the eccentric shaft 12 via a second eccentric shaft bearing 34.

[0024] The first carrier 18 and the second carrier 20 are connected via an inner pin 32. The inner pin 32 axially penetrates an inner pin hole 14h of the external gear 14 at a position radially offset from the axis of the external gear 14.

[0025] One of the carriers 18, 20 and the casing 22 functions as an output member that outputs rotational power to a driven device, and the other functions as a fixed member that is fixed to an external member for supporting a speed reduction device 100. In the present embodiment, the output members are the first carrier 18 and the second carrier 20, and the fixed member is the casing 22.

[0026] In the example of FIG. 2, ten inner pins 32 are arranged at intervals of 36° in the circumferential direction. In FIG. 1, one inner pin 32 is shown. The inner pin 32 has its anti-input side fixed to the first carrier 18 and its input side fixed to the second carrier 20. The inner pin 32 connects the first carrier 18 and the second carrier 20. In the example of FIG. 1, the inner pin 32 is integrally formed with the first carrier 18, and its input side is fixed to the second carrier 20 by a bolt B1. A sleeve 32s is provided on the outer periphery of the inner pin 32. The inner pin 32 is inserted through the inner pin hole 14h with a gap. The inner pin 32 is in contact with a part of the inner pin hole 14h via the sleeve 32s. The inner pin 32 restrains the rotation of the external gear 14 and allows only its rocking.

[0027] The main bearings 24 and 26 are arranged between the first carrier 18 and the casing 22 and between the second carrier 20 and the casing 22. Although there is no limitation on the configuration of the main bearings 24 and 26, in this example, the main bearings 24 and 26 are roller bearings in which the rolling elements 24e and 26e are cylindrical rollers. In FIG. 1, the description of the retainer that holds the rolling elements 24e and 26e is omitted. The outer rings of the main bearings 24 and 26 are supported by the casing 22. The inner ring of the first main bearing 24 is integrally formed with the carrier 18. The inner ring of the second main bearing 26 is integrally formed with the carrier 20.

[0028] The casing 22 is a hollow cylindrical member that surrounds the carriers 18 and 20. As shown in FIG. 1, an oil seal 28 that seals the lubricant from the main bearing 24 is provided between the casing 22 and the first carrier 18.

[0029] Hereinafter, the characteristic configuration of this embodiment will be described.

[0030] The inventor has conducted research on the reduction gear and obtained the following findings. For the purpose of reducing the size and weight of the reduction gear, there is a need to reduce the size of the rolling elements of the eccentric bearing arranged between the external gear and the eccentric shaft. For example, when the reduction gear 100 is applied to a joint of a robot or the like, it is desirable to increase the hollow diameter of the hollow portion H of the eccentric shaft 12 in order to pass wiring and piping. In order to increase the hollow diameter without changing the overall size, it is conceivable to reduce the roller diameter of the roller (rolling element 302) of the eccentric bearing 30. However, when the roller diameter is reduced, the bearing life tends to decrease.

[0031] In order to ensure the bearing life while reducing the roller diameter, it is effective to improve the lubricity. In order to improve the lubricity, it is conceivable to fully fill the inside of the reduction gear with a lubricant. In this case, the periphery of the high-speed rotating eccentric shaft 12 is filled with the lubricant, and the stirring resistance of the lubricant increases and the loss increases. Also, if the filling amount of the lubricant is reduced, it is unevenly distributed to the outer peripheral side due to the centrifugal force during rotation, and the lubricant that contributes to the lubrication of the rolling element 302 decreases, resulting in a reduction in life.

[0032] From these, the inventor has repeatedly considered from the perspective of providing a lubricant holding space around the rolling element 302. As a result, it has been found that by pressing the rolling element 302 with a pressing portion having a predetermined shape, a lubricant holding space can be secured in the vicinity of the rolling element 302. It has been suggested that with this configuration, it is possible to reduce the influence of centrifugal force while suppressing an increase in the stirring resistance of the lubricant. This will be specifically described below.

[0033] Referring to FIGS. 3 to 5, the pressing portion 40 will be described. FIGS. 4 and 5 are cross-sectional views showing an enlarged view of the periphery (range of the broken line E) of the pressing portion 40. FIG. 5 shows a state in which the eccentric body shaft 12 has rotated 180° with respect to FIG. 4. The pressing portion 40 is configured to restrict the axial movement of the eccentric bearing 30 toward the non-input side and to secure a holding space for the lubricant G around the rolling element 302 and reduce the escape of the lubricant G due to centrifugal force.

[0034] As shown in FIGS. 3 to 5, the pressing portion 40 has a cylindrical portion 402, a flange portion 404, and a contact portion 406. The pressing portion 40 can be formed of metal or resin as a hollow annular member. The pressing portion 40 may have the cylindrical portion 402, the flange portion 404, and the contact portion 406 being uniform in the circumferential direction and having no holes, protrusions, recesses, etc., or may be non-uniform in the circumferential direction and have holes, protrusions, recesses, etc. provided in a part of the circumferential direction.

[0035] The cylindrical portion 402 is a cylindrical portion extending in the axial direction, and its outer diameter may be constant in the axial direction or may change in the axial direction. The flange portion 404 is a flange-like portion extending in the radial direction of the cylindrical portion 402. In this example, the flange portion 404 projects radially outward from the input-side end of the cylindrical portion 402. The outer shape of the flange portion 404 may be circular or non-circular when viewed from the axial direction. As shown in FIGS. 3 to 5, the flange portion 404 abuts against the non-input side of the ring portion 306 of the retainer 304 of the eccentric bearing 30.

[0036] The contact portion 406 is a portion that restricts the axial movement of the pressing portion 40. In this example, the contact portion 406 is provided on the side opposite to the flange portion 404 of the cylindrical portion 402 (the anti-input side), and protrudes radially inward from the end of the cylindrical portion 402. The inner shape of the contact portion 406 may be circular or non-circular when viewed axially. As shown in FIGS. 3 to 5, the contact portion 406 is inserted into the axial clearance between the convex portion 126 of the eccentric shaft 12 and the inner ring 334 of the first eccentric shaft bearing 33. The contact portion 406 abuts against the inner ring 334 of the first eccentric shaft bearing 33.

[0037] As shown in FIG. 4, the eccentric shaft 12 has an outer peripheral surface 132 into which the second eccentric shaft bearing 34 is fitted and an outer peripheral surface 133 on which the first eccentric shaft bearing 33 is provided. In the radial direction of the eccentric shaft 12, the direction in which the eccentric portion 128 is most eccentric to the outside is referred to as the maximum eccentricity direction, and the direction eccentric to the opposite side is referred to as the anti-maximum eccentricity direction. In FIGS. 4 and 5, the eccentric portion 128-A of the eccentric shaft 12 indicates the maximum eccentricity direction, and the eccentric portion 128-B indicates the anti-maximum eccentricity direction. The outer periphery of the eccentric portion 128-A in the maximum eccentricity direction is indicated by reference numeral 129, and the outer periphery of the eccentric portion 128-B in the anti-maximum eccentricity direction is indicated by reference numeral 130. The outer peripheral line A is a line obtained by extending the outer peripheral position of the eccentric portion 128-A in the maximum eccentricity direction in the axial direction, and the outer peripheral line B is a line obtained by extending the outer peripheral position of the eccentric portion 128-B in the anti-maximum eccentricity direction in the axial direction.

[0038] In the present embodiment, the axial movement of the eccentric bearing 30 is restricted by the pressing portion 40, and the pressing portion 40 has 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 held in the inner space of the cylindrical portion 402.

[0039] From the viewpoint of securing a holding space for the lubricant G around the rolling elements 302, it is desirable that the axial dimension W1 of the cylindrical portion 402 be large. Therefore, in the present embodiment, the axial dimension W1 of the cylindrical portion 402 is larger than the axial dimension W2 of the ring portion 306 of the retainer 304 of the eccentric bearing 30. In this case, the holding space for the lubricant G can be widened under the condition that the total axial dimension is constant.

[0040] Similarly, from the viewpoint of securing a holding space for the lubricant G, in the present 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, when the total axial dimension of the pressing portion 40 satisfies certain conditions, the holding space for the lubricant G can be widened.

[0041] Similarly, from the viewpoint of securing a holding space for the lubricant G, in the present embodiment, the eccentric shaft 12 has a recess 124 that is recessed radially inward at a position that overlaps with the pressing portion 40 when viewed from the radial direction. By having the recess 124, the holding space for the lubricant G is widened accordingly. Further, the recess 124 may be radially opposed to (overlap when viewed from the radial direction) the ring portion 306 of the retainer 304. In this case, the lubricant G in the recess 124 is likely to get entangled with the eccentric bearing 30, which is advantageous for improving lubricity.

[0042] If the recess 124 is far from the holding space for the lubricant G, the lubricant G in the recess 124 is less likely to get entangled with the eccentric bearing 30. Therefore, in the present embodiment, the recess 124 is radially opposed to (overlaps with) the flange portion 404 when viewed from the radial direction. In this case, the lubricant G in the recess 124 effectively contributes to the lubrication of the eccentric bearing 30.

[0043] If the lubricant G in the recess 124 escapes to the anti-input side, it is disadvantageous for the lubrication of the eccentric bearing 30. Therefore, in the present embodiment, the eccentric shaft 12 has a convex portion 126 that protrudes radially outward at a position adjacent to the side opposite to the eccentric bearing 30 of the recess 124. In this case, the lubricant G in the recess 124 can be blocked to reduce the escape to the anti-input side. In the present embodiment, the axial dimensions of the recess 124 and the convex portion 126 are substantially the same.

[0044] If the positional relationship between the pressing portion 40 and the concave portion 124 is unstable, the effect of improving the lubricity of the eccentric bearing 30 by the lubricant G in the concave portion 124 becomes unstable. Therefore, in the present embodiment, the pressing portion 40 is provided on the side opposite to the flange portion 404 of the cylindrical portion 402, and has a contact portion 406 that contacts the convex portion 126 to restrict the axial movement of the pressing portion 40. In this case, by axially opposing the convex portion 126 to the contact portion 406, the position of the pressing portion 40 with respect to the eccentric shaft 12 of the eccentric body becomes stable, and the effect of improving the lubricity by the lubricant G can be stabilized. The contact portion 406 is interposed in the axial clearance between the inner ring 334 of the first eccentric shaft bearing 33 and the convex portion 126, and is axially in contact with both of them.

[0045] From the viewpoint of securing a holding space for the lubricant G, in the present embodiment, as shown in FIG. 4, in the maximum eccentricity direction of the eccentric shaft 12, the outer periphery 407 of the cylindrical portion 402 is located radially outside the outer periphery 129 of the eccentric portion 128 of the eccentric shaft 12. By increasing the outer periphery 407, the holding space for the lubricant G can be widened. In the present embodiment, in the maximum eccentricity direction of the eccentric shaft 12, the outer periphery of the cylindrical portion 402 is located radially outside the eccentric portion 128 over the entire axial length.

[0046] Further, in the present embodiment, the outer periphery 407 of the cylindrical portion 402 is located radially inside 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. In this case, the possibility that the pressing portion 40 interferes with a retainer (not shown) of the first eccentric shaft bearing 33 can be reduced.

[0047] Further, in the present embodiment, as shown in FIG. 5, in the anti-maximum eccentricity direction of the eccentric shaft 12, the outer periphery 130 (outer peripheral line B) of the eccentric portion 128 of the eccentric shaft 12 is located radially inside the outer periphery 131 of the convex portion 126. Further, in the present embodiment, as shown in FIG. 4, in the maximum eccentricity direction of the eccentric shaft 12, the outer periphery 129 (outer peripheral line A) of the eccentric portion 128 of the eccentric shaft 12 is located radially outside the outer periphery 131 of the convex portion 126.

[0048] In addition, in the present embodiment, as shown in FIGS. 4 and 5, the cylindrical portion 402 has a shape in which the side of the eccentric bearing 30 has a larger diameter in the axial direction, and the outer peripheral contour line is inclined with respect to the axial direction. The cylindrical portion 402 may have, for example, a tapered shape, and the outer peripheral contour line may be a straight line or a curve. In this case, by making the side of the eccentric bearing 30 have a larger diameter, the holding space for the lubricant G can be made wider than in the case of a smaller diameter.

[0049] In addition, in the present embodiment, as shown in FIG. 4, in the maximum eccentricity direction of the eccentric shaft 12, the outer periphery 408 of the flange portion 404 is located radially outside the outer periphery 308 of the retainer 304. In this case, the outer periphery 408 of the flange portion 404 blocks the lubricant G in the vicinity of the retainer 304, reducing the escape of the lubricant G.

[0050] In addition, in the present embodiment, as shown in FIG. 5, in the direction opposite to the maximum eccentricity direction of the eccentric shaft 12, the inner periphery 409 of the flange portion 404 is located radially inside the outer periphery 308 of the retainer 304. In this case, the contact area between the flange portion 404 and the ring portion 306 of the retainer 304 can be ensured, so that the possibility of the retainer 304 coming off during the manufacturing process can be reduced.

[0051] The operation of the speed reduction device 100 configured as described above will be described. When rotation is transmitted from the motor to the eccentric shaft 12, the eccentric portion 128 of the eccentric shaft 12 rotates around the rotation center line passing through the eccentric shaft 12, and the external gear 14 swings via the eccentric bearing 30. When the external gear 14 swings, the meshing position between the external gear 14 and the internal gear 16 shifts sequentially. As a result, every time the eccentric shaft 12 makes one revolution, rotation of one of the external gear 14 and the internal gear 16 corresponding to the difference in the number of teeth between the external gear 14 and the internal gear 16 occurs. In the present embodiment, the external gear 14 rotates, and decelerated rotation is output from the first carrier 18 and the second carrier 20 via the inner pin 32.

[0052] The features of the speed reducer 100 configured as described above will be described. The speed reducer 100 is an eccentric swing type speed reducer having an external gear 14, an eccentric shaft 12 that eccentrically swings the external gear 14, and an eccentric bearing 30 disposed between the external gear 14 and the eccentric shaft 12. The eccentric bearing 30 is restricted from axial movement by a pressing portion 40. The pressing portion 40 has a cylindrical portion 402 extending in the axial direction and a flange portion 404 extending in the radial direction of the cylindrical portion 402.

[0053] According to this configuration, the pressing portion 40 can secure a space for holding the lubricant near the rolling elements 302. Also, according to this configuration, the influence of centrifugal force can be reduced while suppressing an increase in the stirring resistance of the lubricant G. As a result, the lubricity of the eccentric bearing 30 can be improved.

[0054] As described above, the examples of the embodiments of the present invention have been described in detail. The above-described embodiments are merely specific examples for implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are possible without departing from the inventive concept defined in the claims. In the above-described embodiments, regarding the content for which such design changes are possible, explanations have been given with notations such as "in the embodiment" and "in the embodiment", but design changes are not necessarily not allowed for the content without such notations. Also, the hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached.

[0055] Hereinafter, modification examples will be described. In the drawings and descriptions of the modification examples, the same or equivalent components and members as those in the embodiment are denoted by the same reference numerals. Descriptions overlapping with those of the embodiment are appropriately omitted, and the configurations different from those of the embodiment will be mainly described.

[0056] [Modification Example] In the description of the embodiment, an example in which the reduction gear 100 is a center crank type eccentric swing type reduction gear has been shown, but the present invention is not limited to this. The reduction gear only needs to be one in which an eccentric bearing is arranged between the external gear and the eccentric shaft, and the type of the reduction mechanism is not particularly limited. For example, it may be a so-called distribution type eccentric swing type reduction gear in which a plurality of crank shafts are arranged at positions offset from the center.

[0057] In the description of the embodiment, an example in which the number of external gears 14 is 2 has been shown, but the number of external gears may be 1 or 3 or more.

[0058] In the description of the embodiment, an example in which an inner pin 32 that contributes to the transmission of the driving force of the external gear 14 is provided as a pin member for connecting the carriers 18 and 20 has been shown. A carrier pin that does not contribute to the transmission of the driving force may be provided separately from the inner pin 32 as a pin member for connecting the carriers 18 and 20.

[0059] In the description of the embodiment, an example in which the inner pin 32 is integrally formed with the first carrier 18 has been shown, but the inner pin 32 may be formed separately from the first carrier 18 and connected by a fixture such as a bolt.

[0060] In the description of the embodiment, an example in which the eccentric bearing 30 does not have an inner ring and an outer ring has been shown, but the eccentric bearing 30 may have an inner ring or an outer ring.

[0061] In the description of the embodiment, an example in which the inner rings of the main bearings 24 and 26 are integrally formed with the carriers 18 and 20 has been shown, but the inner ring of the main bearing may be separate from the carrier.

[0062] In the description of the embodiments, an example was shown in which the rolling elements 24e and 26e of the main bearings 24 and 26 are cylindrical rollers. However, the rolling elements of the main bearings may have a shape different from that of cylindrical rollers, such as tapered rollers or spheres. Further, the main bearings are not limited to those composed of a pair of bearings, and for example, a cross roller bearing may be used. In the description of the embodiments, an example was shown in which the rolling element 332 of the eccentric shaft bearings 33 and 34 is a sphere. However, the rolling elements of the eccentric shaft bearings may have a shape different from that of a sphere (for example, a cylindrical roller shape or the like). In the description of the embodiments, an example was shown in which the rolling element 302 of the eccentric bearing 30 is a cylindrical roller. However, the rolling elements of the eccentric bearing may have a shape different from that of a cylindrical roller (for example, a sphere or the like).

[0063] In the description of the embodiments, as an adjacent example, an example was shown in which the convex portion 126 of the eccentric shaft 12 is disposed immediately adjacent to the concave portion 124. However, a flat portion or the like may be provided between the convex portion and the concave portion of the eccentric shaft.

[0064] In the description of the embodiments, as an example in which, in the maximum eccentricity direction of the eccentric shaft 12, the outer periphery of the cylindrical portion 402 is located radially outside the eccentric portion 128 over the entire axial length in the maximum eccentricity direction of the eccentric shaft 12, an example was shown. However, the fact that the outer periphery of the cylindrical portion is located radially outside the eccentric portion 128 may be a configuration in which a part of the axial range of the outer periphery of the cylindrical portion is located radially outside the eccentric portion.

[0065] Each of the above-described modified examples exhibits the same operations and effects as the embodiments.

[0066] Any combination of the components of the above-described embodiments and the modified examples is also useful as an embodiment of the present invention. The new embodiments resulting from the combination have the effects of the combined embodiments and modified examples.

Description of Reference Numerals

[0067] 12 eccentric body shaft, 14 external gear, 30 eccentric body bearing, 40 pressing part, 124 concave part, 126 convex part, 128 eccentric part, 129, 130, 131 outer circumference, 304 retainer, 306 ring part, 308 outer circumference, 335 outer circumference, 402 cylindrical part, 404 flange part, 406 contact part, 407, 408 outer circumference, W1, W2, W3 axial dimensions, 100 eccentric swing type reduction gear device.

Claims

1. An external gear, An eccentric shaft for eccentrically swinging the external gear, In an eccentric swing type reduction gear having an eccentric bearing disposed between the external gear and the eccentric shaft, The eccentric bearing is restricted from axial movement by a pressing portion, The pressing portion has a cylindrical portion extending in the axial direction and a flange portion extending in the radial direction of the cylindrical portion, A restricting portion for restricting the movement of the pressing portion toward the eccentric bearing side is provided on the eccentric shaft, The eccentric shaft has a recess recessed radially inward from the outer shape of the restricting portion between the restricting portion and the eccentric bearing, and is characterized in that it is an eccentric swing type reduction gear.

2. The eccentric swing type reduction gear according to claim 1, wherein the axial dimension of the cylindrical portion is larger than the axial dimension of the ring portion of the retainer of the eccentric bearing.

3. The eccentric swing type reduction gear according to claim 1 or 2, wherein the axial dimension of the cylindrical portion is larger than the axial dimension of the flange portion.

4. The eccentric swing type reduction gear according to any one of claims 1 to 3, wherein the recess overlaps with the pressing portion when viewed in the radial direction.

5. The eccentric swing type reduction gear according to claim 4, wherein the recess overlaps with the flange portion when viewed in the radial direction.

6. An external gear, An eccentric shaft for eccentrically swinging the external gear, In an eccentric swing type reduction gear having an eccentric bearing disposed between the external gear and the eccentric shaft, The eccentric bearing is restricted from axial movement by a pressing portion, The pressing portion has a cylindrical portion extending in the axial direction and a flange portion extending in the radial direction of the cylindrical portion, The eccentric shaft has a recess recessed radially inward at a position overlapping with the pressing portion when viewed in the radial direction, The eccentric shaft has a convex portion protruding radially outward at a position adjacent to the side opposite to the eccentric bearing of the recess, and is characterized in that it is an eccentric swing type reduction gear.

7. The pressing portion has a contact portion provided on the side opposite to the flange portion of the cylindrical portion, and the contact portion contacts the restricting portion to restrict the axial movement of the pressing portion, and is characterized in that it is an eccentric swing type reduction gear according to claim 1.

8. The eccentric swing type reduction gear according to any one of claims 1 to 7, wherein the outer circumference of the cylindrical portion is located radially outside the outer circumference of the eccentric portion of the eccentric shaft in the maximum eccentric direction of the eccentric shaft.

9. The eccentric swing type reduction gear according to claim 7, wherein, in the direction opposite to the maximum eccentricity direction of the eccentric body axis, the outer periphery of the eccentric portion of the eccentric body axis is located radially inward of the outer periphery of the restricting portion.

10. The eccentric swing type reduction gear according to any one of claims 1 to 9, wherein the recess overlaps the eccentric bearing when viewed in the radial direction.

11. An external gear, An eccentric body shaft for eccentrically swinging the external gear, In an eccentric swing type reduction gear having an eccentric bearing disposed between the external gear and the eccentric body shaft, The movement of the eccentric bearing in the axial direction is restricted by a pressing portion, The pressing portion has a cylindrical portion extending in the axial direction and a flange portion extending in the radial direction of the cylindrical portion, The eccentric swing type reduction gear, wherein, in the maximum eccentricity direction of the eccentric body shaft, the outer periphery of the flange portion is located radially outside the outer periphery of the retainer of the eccentric bearing.

12. The eccentric swing type reduction gear according to any one of claims 1 to 11, wherein, in the direction opposite to the maximum eccentricity direction of the eccentric body shaft, the inner periphery of the flange portion is located radially inside the outer periphery of the retainer of the eccentric bearing.

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