Eccentric oscillation type gear device

Abstract

To further restrain entry of dust into bearings.SOLUTION: An eccentric oscillation type gear device 1 comprises: external gears 22A and 22B provided with offset holes at positions offset from centers; a crankshaft 21 comprising eccentric bodies 21A and 21B inserted into the offset holes, and for oscillating the external gears 22A and 22B; crankshaft bearings 26 and 27 supporting the crankshaft 21; eccentric body bearings 25 arranged between the external gears 22A and 22B and the eccentric bodies 21A and 21B; and spacers 4 arranged on side parts of the crankshaft bearings 26 and 27. The spacers 4 inhibit the entry of abrasion powder into at least one of the crankshaft bearings 26 and 27 and the eccentric body bearings 25.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, a so-called sorting type eccentric swing type gear device has been known (see, for example, Patent Document 1). In the sorting type eccentric swing type gear device, a crankshaft having an eccentric body that swings a swing gear (external gear) is disposed at a position offset from the center.

[0003] In the sorting type eccentric swing type gear device, the distance from the meshing portion of the external gear to the eccentric body bearing and the bearing for the crankshaft is relatively short. Therefore, wear dust (powder) generated at the meshing portion of the external gear may enter the bearing, and the bearing life may be shortened.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to further suppress the entry of dust into the bearing.

Means for Solving the Problems

[0006] The present invention is an external gear provided with an offset hole at a position offset from the center, a crankshaft having an eccentric body inserted into the offset hole and swinging the external gear, a bearing for the crankshaft that supports the crankshaft, and an eccentric body bearing disposed between the external gear and the eccentric body, in an eccentric swing type gear device. It has a spacer disposed on a side portion of the bearing for the crankshaft, and the spacer inhibits entry of wear debris into at least one of the bearing for the crankshaft and the eccentric body bearing.

Advantages of the Invention

[0007] According to the present invention, entry of dust into the bearing can be further suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] [Overall Configuration of Eccentric Oscillation Type Gear Device] FIG. 1 is a longitudinal sectional view of an eccentric oscillation type gear device 1 according to the present embodiment. Hereinafter, the direction along the central axis Ax1 in the drawing is referred to as the "axial direction". Also, among the axial directions, the side connected to the external driven member (the left side in FIG. 1) is referred to as the "load side", and the side opposite to the load side (the right side in FIG. 1) is referred to as the "anti-load side".

[0011] As shown in FIG. 1, the eccentric swing type gear device 1 according to the present embodiment is a so-called distribution type eccentric swing type speed reducer. Specifically, the eccentric swing type gear device 1 includes a crankshaft (eccentric body shaft) 21 having eccentric bodies 21A and 21B, a first external gear 22A in which the eccentric body 21A of the crankshaft 21 is inserted into a through hole (offset hole) offset from the axis (central axis Ax1), and a second external gear 22B in which the eccentric body 21B of the crankshaft 21 is inserted into a through hole (offset hole) offset from the axis.

[0012] The crankshaft 21 has a distribution gear 23 that meshes with the output shaft of a motor (not shown), and rotation is input from the input shaft via the distribution gear 23. The through holes of the external gears 22A and 22B are provided at a plurality of locations (for example, three locations) in the circumferential direction around the central axis Ax1, and a plurality of crankshafts 21 are passed through. The eccentric bodies 21A and 21B are rotatably arranged in the through holes of the external gears 22A and 22B via eccentric body bearings 25 arranged between the external gears 22A and 22B.

[0013] Furthermore, the eccentric swing type gear device 1 includes an output shaft (carrier) 24 arranged on the side portions of the external gears 22A and 22B on the load side, a support plate 241 fixed to the anti-load side of the output shaft 24, and a casing 30 having an internal gear 32 that meshes with the external gears 22A and 22B. The crankshaft 21 is supported by crankshaft bearings 26 and 27 arranged between the support plate 241 and the output shaft 24. The crankshaft bearings 26 and 27 are tapered roller bearings in the present embodiment. The casing 30 rotatably supports the support plate 241 and the output shaft 24 via main bearings 28 and 29 arranged between the support plate 241 and the output shaft 24. The main bearings 28 and 29 are tapered roller bearings in the present embodiment. The output shaft 24 is fixed to a driven member (not shown).

[0014] With such a configuration, in the eccentric swing type gear device 1, when rotational motion is transmitted to the crankshaft 21 via the distribution gear 23 by driving the motor, the eccentric bodies 21A and 21B rotate to eccentrically swing the external gear wheels 22A and 22B in different phases from each other. Due to this eccentric swing, the meshing positions of the external gear wheels 22A and 22B with the internal gear 32 change in the circumferential direction around the central axis Ax1, and since the number of teeth of both is different, the external gear wheels 22A and 22B rotate (revolve). Then, the revolving components of the external gear wheels 22A and 22B are output to the driven member via the output shaft 24.

[0015] [Contamination prevention structure of crankshaft] FIG. 2 is an enlarged view of the R portion of FIG. 1. A spacer 4 is disposed on the crankshaft 21 to prevent wear powder (contamination. Hereinafter simply referred to as "wear powder") generated at the meshing portion, bearings, etc. from entering the eccentric body bearing 25, the crankshaft bearings 26, 27, the main bearings 28, 29. The spacer 4 is formed in a substantially annular plate shape made of metal and is disposed concentrically with respect to the central axis Ax2 of the crankshaft 21. The spacer 4 of the present embodiment includes a first spacer 41 and a second spacer 42. Note that the spacer 4 only needs to inhibit the entry of wear powder into at least one of the crankshaft bearings 26, 27 and the eccentric body bearing 25. Here, "inhibition of the entry of wear powder" includes "narrowing of the passage", and "narrowing of the passage" includes a labyrinth structure. Further, "inhibition of the entry of wear powder" includes a configuration in which a filter that inhibits wear powder is disposed in a portion that narrows (narrows) the passage. Also, hereinafter, unless otherwise specified, the "radial direction" refers to a direction perpendicular to the central axis Ax2 of the crankshaft 21, and the "circumferential direction" refers to a rotational direction centered on the central axis Ax2 of the crankshaft 21.

[0016] <First spacer> The first spacer 41 is disposed between the first external gear wheel 22A and the crankshaft bearing 26 and between the second external gear wheel 22B and the crankshaft bearing 27, respectively. Hereinafter, the configuration of the first spacer 41 on the anti-load side disposed between the first external gear 22A and the bearing 26 for the crankshaft will be described. Since the first spacer 41 on the load side disposed between the second external gear 22B and the bearing 27 for the crankshaft is configured substantially in the same manner with the axial direction reversed with respect to the first spacer 41 on the anti-load side, the description thereof will be omitted.

[0017] As shown in FIG. 2, the first spacer 41 suppresses the entry of wear powder into the eccentric bearing 25, the main bearing 28, and the bearing 26 for the crankshaft. Further, the first spacer 41 restricts the axial movement of the cage 25b of the eccentric bearing 25. Specifically, the first spacer 41 has an inner diameter portion 41a, a crushed and bent portion 41b, and an outer diameter portion 41c. Among these, the inner diameter portion 41a is formed in a disc shape orthogonal to the axial direction, and the inner diameter side end portion is axially sandwiched between the inner ring 26b of the bearing 26 for the crankshaft and the crankshaft 21 (eccentric body 21A).

[0018] A plurality of hole portions 41d as passages for the lubricant are evenly arranged in the circumferential direction in the inner diameter portion 41a. Each hole portion 41d overlaps with the adjacent eccentric bearing 25 in the axial direction (overlaps when viewed from the axial direction). Each hole portion 41d only needs to overlap with the eccentric bearing 25 at least partially in the axial direction. However, it is more preferable that each hole portion 41d is formed so as to include a portion that overlaps with both of the rolling elements 25a of the two rows of eccentric bearings 25 in the axial direction. In other words, it is more preferable that each hole portion 41d is formed so as to include a portion (radial direction range) between the maximum inner diameter and the minimum outer diameter of the two rows of eccentric bearings 25. The shape of each hole portion 41d is not particularly limited, and for example, as shown in FIGS. 3(a) and (b), it may be circular or square, or may be trapezoidal with a width narrowing toward the inner diameter side as shown in FIG. 3(c).

[0019] With such hole portions 41d, the lubricant can be suitably circulated between the eccentric bearing 25 and the bearing 26 for the crankshaft. That is, the lubricant is supplied and enclosed into the device from the anti-load side (GR part in FIG. 1) of the crankshaft 21 and is supplied to the eccentric bearing 25, the bearings 26, 27 for the crankshaft, and the main bearings 28, 29. At this time, although the inner diameter part 41a of the first spacer 41 is arranged between the eccentric bearing 25 and the bearings 26, 27 for the crankshaft, a hole part 41d is formed in the inner diameter part 41a so as to overlap the eccentric bearing 25 in the axial direction. Therefore, the lubricant can be suitably flowed in the axial direction through the hole part 41d. Also, the inner ring 26b of the bearing 26 for the crankshaft has a corner part on the outer diameter side of the load side (eccentric bearing 25 side) cut out in a tapered shape to form a notch part 26e. This notch part 26e (tapered surface) overlaps the surface (outer peripheral surface) of the eccentric body 21A where the eccentric bearing 25 is arranged in the axial direction. Therefore, compared with the case where the inner ring 26b of the bearing 26 for the crankshaft does not have the notch part 26e and the end face on the load side stands upright, the lubricant can be suitably flowed in the axial direction.

[0020] The crushed and bent part 41b is continuous with the outer diameter end of the inner diameter part 41a, and is formed by bending toward the load side from the outer diameter end and then folding back to the anti-load side. That is, the crushed and bent part 41b includes an extending part extending in the axial direction. The crushed and bent part 41b corresponds to an example of the "first inhibiting part" according to the present invention. The extending part according to the present invention may be provided so as to protrude in the axial direction from a part extending in the radial direction, or a plurality of extending parts may be provided. The crushed and bent part 41b faces a stepped part 221 formed on the anti-load side surface of the first external gear 22A. The stepped part 221 of the first external gear 22A is formed so as to be located stepwise on the load side as it goes toward the inner diameter side. The crushed and bent part 41b faces the stepped part 22a such that the part on the load side overlaps the stepped part 22a in the radial direction (overlaps when viewed from the radial direction). Also, the radial position of the crushed and bent part 41b is set so as not to contact the stepped part 22a of the first external gear 22A even when the first external gear 22A is eccentric to the innermost diameter side around the central axis Ax1. The stepped part 22a is an example of the facing part according to the present invention, and it suffices that it faces the extending part in the radial direction. For example, there may be a continuous inclined part without steps, and the inclined part may face the extending part in the radial direction. As a result, the crushed and bent portion 41b defines a communication passage including a labyrinth structure with the stepped portion 22a of the first external gear 22A. Here, the labyrinth structure refers to a configuration including a passage portion having at least an axial direction component and a passage portion having a radial direction component. Further, at least one of these passage portions is narrower than the upstream side or the downstream side of the communication passage, and is a constricted portion where a large resistance acts on the lubricant passing therethrough. With this labyrinth structure, it is possible to preferably prevent the wear powder generated at the meshing portion between the first external gear 22A and the internal gear 32 from entering the eccentric bearing 25.

[0021] The outer diameter portion 41c is continuous with the end portion on the anti-load side of the crushed and bent portion 41b and is formed in a disc shape perpendicular to the axial direction. The outer diameter portion 41c corresponds to an example of the "second inhibiting portion" according to the present invention. The axial position of the outer diameter portion 41c corresponds to the retainer 28d of the main bearing 28, and the end portion on the outer diameter side faces the retainer 28d in the radial direction and forms a constricted portion therebetween. With this constricted portion, it is possible to preferably prevent the wear powder generated at the meshing portion between the first external gear 22A and the internal gear 32 from entering the main bearing 28 or the crankshaft bearing 26. Further, the axial position of the outer diameter portion 41c is different (not overlapping in the axial direction) from the communication passage 28e that communicates between the inner ring 28b of the main bearing 28 and the retainer 28d. Specifically, the outer diameter portion 41c does not project axially beyond the flange portion of the retainer 28d. Therefore, the outer diameter portion 41c does not block the communication passage 28e and inhibit the supply of lubricant to the main bearing 28.

[0022] <Second Spacer> The second spacer 42 is disposed between the crankshaft bearing 26 and the distribution gear 23 and suppresses the entry of wear powder into the crankshaft bearing 26. Specifically, the second spacer 42 has an inner diameter portion 42a and a U-shaped portion 42b. Among these, the inner diameter portion 42a is formed in a disc shape perpendicular to the axial direction and is axially sandwiched between the inner ring 26b of the crankshaft bearing 26 and the sleeve 231.

[0023] The U-shaped portion 42b is formed in a U-shape (concave shape) that opens to the load side. More specifically, the U-shaped portion 42b is formed such that after bending from the outer diameter end of the inner diameter portion 42a toward the non-load side, it bends toward the outer diameter side, and its outer diameter end bends toward the load side. Thereby, the space inside the U-shaped portion 42b functions as a grease pocket P that stores lubricant from the load side (the side of the crankshaft bearing 26). The crankshaft bearing 26, which is a tapered roller bearing, allows grease to easily move toward the inner diameter side of the rolling elements (rollers) 26a, that is, toward the non-load side. The U-shaped portion 42b can suitably receive the lubricant that has moved to this non-load side.

[0024] The end portion on the outer diameter side of the U-shaped portion 42b axially faces the C-ring 242 that regulates the axial position of the outer ring 26c of the crankshaft bearing 26. Also, the end portion on the outer diameter side of the U-shaped portion 42b radially faces the support plate 241 and forms a constricted portion therebetween. This constricted portion can suitably prevent wear debris generated at the meshing portion of the idler gear 23 from entering the crankshaft bearing 26 (and further the eccentric bearing 25). Also, the end portion on the outer diameter side of the U-shaped portion 42b constitutes a labyrinth structure with the support plate 241 and the C-ring 242. Thereby, the entry of wear powder into the crankshaft bearing 26 (and further the eccentric bearing 25) can be more suitably inhibited.

[0025] [Technical Effects of the Embodiment] As described above, according to the present embodiment, the spacer 4 disposed on the side portion of the crankshaft bearing 26 inhibits the entry of wear debris (dust) into at least one of the crankshaft bearing 26 and the eccentric bearing 25. Thereby, the entry of wear powder into at least one of the crankshaft bearing 26 and the eccentric bearing 25 can be further suppressed.

[0026] Further, according to the present embodiment, among the spacers 4, a first spacer 41 disposed between the first external gear 22A and the crankshaft bearing 26 has a crushed and bent portion 41b (first inhibiting portion) that inhibits the entry of wear debris into the eccentric bearing 25. With this crushed and bent portion 41b, the entry of wear powder into the eccentric bearing 25 can be suppressed. Furthermore, the first spacer 41 has an outer diameter portion 41c (second inhibiting portion) that cooperates with the retainer 28d of the main bearing 28 to inhibit the entry of wear debris into the crankshaft bearing 26. With this outer diameter portion 41c, the entry of wear debris into the crankshaft bearing 26 can be suppressed.

[0027] Also, according to the present embodiment, the external gear has a stepped portion 221 that faces the radially extending portion in the axial direction of the crushed and bent portion 41b. Thereby, a labyrinth structure is formed by the crushed and bent portion 41b and the stepped portion 221, and the entry of wear powder into the eccentric bearing 25 can be suppressed. Also, since it is a non-contact labyrinth structure, loss torque can be suppressed.

[0028] Also, according to the present embodiment, the outer diameter portion 41c (second inhibiting portion) of the first spacer 41 forms a constricted portion facing the retainer 28d of the main bearing 28 in the radial direction. With this constricted portion, the entry of wear powder into the main bearing 28 and the crankshaft bearing 26 can be suppressed. Further, the outer diameter portion 41c (second inhibiting portion) does not overlap the communication passage 28e that communicates between the inner ring 28b of the main bearing 28 and the retainer 28d in the axial direction. Therefore, the outer diameter portion 41c does not block the communication passage 28e and inhibit the supply of lubricant to the main bearing 28.

[0029] Also, according to the present embodiment, the first spacer 41 has a hole portion 41d in a portion that overlaps the eccentric bearing 25 in the axial direction. With this hole portion 41d, the lubricant can be suitably flowed in the axial direction between the eccentric bearing 25 and the crankshaft bearing 26.

[0030] Further, according to the present embodiment, among the spacers 4, the second spacer 42 disposed between the bearing 26 for the crankshaft and the distribution gear 23 inhibits the entry of wear debris from the distribution gear 23 side into the bearing 26 for the crankshaft. By means of this second spacer 42, it is possible to suppress the entry of wear debris into the bearing 26 for the crankshaft. Also, the bearing space for the crankshaft can be isolated from the surrounding gears (distribution gear, external gear).

[0031] Further, according to the present embodiment, the second spacer 42 has a U-shaped portion 42b that opens to the bearing 26 for the crankshaft side. Thereby, the space inside the U-shaped portion 42b can function as a grease pocket P.

[0032] [Other] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments. For example, in the above embodiment, the outer diameter portion 41c of the first spacer 41 is set to have an axial position corresponding to the retainer 28d of the main bearing 28. However, it is sufficient that the outermost diameter portion of the outer diameter portion 41c forms a constricted portion by facing the retainer 28d in the radial direction. For example, as shown in FIG. 4, the outer diameter portion 41c of the first spacer 41 may have a shape that bends outward in the diameter direction on the load side from the end of the crushed and bent portion 41b, further than the retainer 28d of the main bearing 28, and then bends in the anti-load direction at the outermost diameter portion and extends to a portion facing the retainer 28d. In this case, the distance between the outer diameter portion 41c of the first spacer 41 and the first external gear 22A can be made smaller than in the above embodiment. As a result, the entry of wear powder into the eccentric bearing 25 can be more suitably suppressed.

[0033] Also, the bearing types of the eccentric bearing, the bearing for the crankshaft, and the main bearing are not particularly limited. Furthermore, the present invention is not particularly limited as long as it is an eccentric swing type gear device in which the crankshaft is arranged at an offset position from the center, and can be widely applied to eccentric swing type gear devices. For example, it can also be applied to a device in which a ring gear is meshed with a distribution gear of a plurality of crankshafts, and a pinion shaft offset from the center is meshed with the ring gear.

[0034] In addition, the details shown in the above embodiments can be appropriately changed without departing from the gist of the invention.

Explanation of Reference Numerals

[0035] 1 Eccentric swing type gear device 4 Spacer 21 Crankshaft 21A, 21B Eccentric body 22a Step portion 22A First external gear 22B Second external gear 23 Distribution gear 24 Output shaft 25 Eccentric body bearing 26, 27 Bearings for crankshaft 26b Inner ring 26e Notch portion 28, 29 Main bearings 28b Inner ring 28d Retainer 28e Communication passage 30 Casing 32 Internal gear 41 First spacer 41a Inner diameter portion 41b Crushed and bent portion (first inhibiting portion, extending portion) 41c Outer diameter portion (second inhibiting portion) 41d Hole portion 42 Second spacer 42a Inner diameter portion 42b U-shaped portion (concave portion) 221 Step portion Ax2 Central axis P Grease pocket

Claims

1. An external gear having an offset hole provided at a position offset from the center, A crankshaft having an eccentric body inserted into the offset hole and configured to swing the external gear, A bearing for the crankshaft that supports the crankshaft, In an eccentric swing type gear device having an eccentric bearing disposed between the external gear and the eccentric body, It has a spacer disposed on a side portion of the bearing for the crankshaft, The spacer inhibits the entry of wear debris into at least one of the bearing for the crankshaft and the eccentric bearing, An eccentric swing type gear device.

2. Further comprising a carrier disposed on a side portion of the external gear, a casing having an internal gear meshing with the external gear, and a main bearing disposed between the carrier and the casing, The spacer includes a first spacer disposed between the external gear and the bearing for the crankshaft, The first spacer, A first inhibiting portion that inhibits the entry of wear debris into the eccentric bearing, A second inhibiting portion that cooperates with a retainer of the main bearing to inhibit the entry of wear debris into the bearing for the crankshaft, And has, The eccentric swing type gear device according to claim 1.

3. The first spacer has an extending portion extending in the axial direction, The external gear has an opposing portion that opposes the extending portion in the radial direction, The eccentric swing type gear device according to claim 2.

4. The first spacer has a hole portion in a portion that overlaps the eccentric bearing in the axial direction, The eccentric swing type gear device according to claim 2 or 3.

5. The second inhibiting portion, Opposes the retainer in the radial direction to form a constricted portion, The communication passage that communicates between the inner ring of the main bearing and the retainer does not overlap in the axial direction. The eccentric swing type gear device according to claim 2.

6. The crankshaft has a distribution gear. The spacer includes a second spacer disposed between the bearing for the crankshaft and the distribution gear. The second spacer inhibits wear debris from the distribution gear side from entering the bearing for the crankshaft. The eccentric swing type gear device according to claim 1 or 2.

7. The second spacer has a concave portion that opens to the bearing side for the crankshaft. The eccentric swing type gear device according to claim 6.

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