JP2013086687A - Power-assisted bicycle driving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wheels from being locked in the case wherein a rotor and a reduction gear are locked.SOLUTION: The electric bicycle driving unit includes: a rotor supported freely to rotate; a stator provided outside in the radial direction of the rotor to rotate the rotor; a reduction gear which reduces the speed of rotation from the rotor; a connecting part 29 connecting the final stage of the reduction gear to a hub of a wheel to transmit the rotation, whose speed is reduced by the reduction gear, to the hub of the wheel; and a connection releasing part 35 formed in the connecting part to release the connection between the final stage of the reduction gear and the hub of the wheel, which is connected by the connecting part, by breaking itself.

Description

  The present invention relates to a drive unit for an electric bicycle.

  In the configuration of Patent Document 1, the planetary decelerated power is transmitted to the internal gear, and further, the power is transmitted to the side wall portion of the hub body where the internal gear is fixed with a screw to drive the front wheels. Yes.

JP 2009-12542 A

  However, in the configuration of Patent Document 1, the stator of the molded motor is fixed to the hub shaft, and when the rotor is locked (unrotatable) due to some trouble, the speed reduction mechanism, the side wall, and the hub body are also locked. The front wheels lock.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric bicycle drive unit that can prevent wheels from being locked when a rotor or a speed reduction mechanism is locked.

  The drive unit of the electric bicycle according to claim 1, wherein the rotor is rotatably supported, the stator is provided on the radially outer side of the rotor, the stator for rotating the rotor, and the rotation from the rotor is decelerated. A speed reduction mechanism, a connecting portion for connecting a final stage of the speed reduction mechanism and a wheel hub, and a rotation portion that transmits the rotation decelerated by the speed reduction mechanism to the wheel hub, and formed in the connection portion. A connection releasing part capable of releasing the connection between the final stage of the mechanism and the wheel hub by the connecting part.

  According to this drive unit, the connection release part formed in the connection part can release the connection by the connection part between the final stage of the speed reduction mechanism and the wheel hub by breaking. Therefore, when the rotor or the speed reduction mechanism is locked, the connection between the final stage of the speed reduction mechanism and the wheel hub is released by the connection release unit, thereby preventing the wheel from being locked.

  In the drive unit for the electric bicycle according to claim 2, the connecting portion is made of a material different from that of the final stage of the speed reduction mechanism.

  According to this drive unit, distortion is likely to occur between the connecting portion and the final stage of the speed reduction mechanism, and the disconnection portion is broken compared to the case where the connecting portion is made of the same material as the final stage of the speed reduction mechanism. Therefore, it is possible to easily release the connection between the final stage of the speed reduction mechanism and the wheel hub.

  In the drive unit for the electric bicycle according to claim 3, the connecting portion is made of a material having lower strength than the final stage of the speed reduction mechanism.

  According to this drive unit, it becomes easy to break the connection release portion while maintaining the strength of the final stage of the speed reduction mechanism.

  In the drive unit of the electric bicycle according to claim 4, the final stage of the speed reduction mechanism is made of a metal material, and the connecting portion is made of a resin material.

  According to this drive unit, a difference in strength between the connecting portion and the final stage of the speed reduction mechanism can be easily obtained. Therefore, the connection releasing portion can be easily broken while maintaining the strength of the final stage of the speed reduction mechanism more effectively.

  In the drive unit for the electric bicycle according to claim 5, the connecting portion is formed integrally with the final stage of the speed reduction mechanism by insert molding.

  According to this drive unit, since the connecting portion and the final stage of the speed reduction mechanism are integrally formed, handling of the connecting portion is easier than when the connecting portion and the final stage of the speed reduction mechanism are configured separately. It is.

  In the drive unit of the electric bicycle according to claim 6, the connection release part is configured by a weak part made weak by a notch formed in the connection part.

  According to this drive unit, a connection release part can be comprised, without adding components.

It is side surface sectional drawing of the drive unit which concerns on one Embodiment of this invention. It is a disassembled perspective view of the drive unit shown by FIG. FIG. 3 is a perspective view of the cover assembly shown in FIG. 2. It is a perspective view which shows the internal gear and connection part which concern on this embodiment. It is side surface sectional drawing which shows the internal gear and connection part which concern on this embodiment. It is a perspective view which expands and shows the connection cancellation | release part which concerns on this embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an electric bicycle drive unit 10 according to an embodiment of the present invention includes a pair of fixed shafts 12, 14, a rotor 16, a stator 18, a motor housing 20, and an external gear 22. And a carrier 24, a wheel hub 26, which is an example of a rotating member, and an internal gear 28 as main components. In the figure, the arrow A direction indicates the axial direction of the drive unit 10, the arrow A1 direction indicates the axial outer side of the drive unit 10, and the arrow A2 direction indicates the axial inner side of the drive unit 10. With the axial center S (see FIG. 1) of the drive unit 10 (rotor 16, stator 18) as the boundary, the axial direction away from the axial center S is the axial outer side, and the axial direction approaching the axial center S is the axial direction. Inside. In the figure, the arrow B direction indicates the radial direction of the drive unit 10, the arrow B1 direction indicates the radial outside of the drive unit 10, and the arrow B2 direction indicates the radial inner side of the drive unit 10.

  The pair of fixed shafts 12 and 14 are arranged coaxially with each other. Screw portions 12A and 14A are formed on the pair of fixed shafts 12 and 14, respectively, and nuts 30 and 32 are screwed onto the screw portions 12A and 14A, respectively. One fixed shaft 12 is fixed to the outside using a nut 30, and the other fixed shaft 14 is fixed to the outside using a nut 32. The outside in this case is, for example, a bicycle body.

  The rotor 16 constitutes a brushless motor together with a stator 18 described later. The rotor 16 has an output shaft 34 disposed coaxially with the pair of fixed shafts 12 and 14 between the pair of fixed shafts 12 and 14. On the other fixed shaft 14 side of the output shaft 34, an eccentric shaft 36 is provided in an eccentric state. The eccentric shaft 36 is coupled to the output shaft 34 by a serration coupling portion 38, and has a shaft portion 36A that protrudes on the opposite side of the output shaft 34 in the axial direction. The shaft portion 36 </ b> A is formed coaxially with the output shaft 34.

  The stator 18 is formed in an annular shape and is provided outside the rotor 16 in the radial direction. In the brushless motor having the rotor 16 and the stator 18, when a rotating magnetic field is generated in the stator 18, an attractive / repulsive force acts between the rotor 16 and the stator 18, and the output shaft 34 is rotated together with the rotor 16. The

  The motor housing 20 includes a first housing 40 attached to the stator 18 from one fixed shaft 12 side, and a second housing 42 attached to the stator 18 from the other fixed shaft 14 side. The first housing 40, the stator 18, and the second housing 42 are fixed by bolts 44. Further, the first housing 40 and the stator 18 are fixed by bolts 45.

  The first housing 40 is formed in a flat container shape having a bottom portion on the one fixed shaft 12 side. A disc-like spacer 46 is fixed to the bottom of the first housing 40 with bolts 48. A cylindrical portion 50 is formed at the center of the spacer 46, and one fixed shaft 12 is press-fitted and fixed to the cylindrical portion 50.

  On the other hand, the second housing 42 is formed in a disc shape. The second housing 42 is an example of an opposing wall portion, and is opposed to a carrier body 68 formed on the carrier 24 described later and the output shaft 34 in the axial direction. An accommodation recess 52 is formed in the second housing 42. The housing recess 52 has a concave shape that opens toward the carrier body 68 and is inserted inside the stator 18.

  An annular bearing housing 54 is formed at the center of the bottom of the housing recess 52, and a bearing 56, which is an example of a first bearing, is housed in the bearing housing 54. Similarly, a bearing housing portion 58 is formed at the center of the bottom of the first housing 40 described above, and a bearing 60 that is an example of a first bearing is housed in the bearing housing portion 58. The pair of bearings 56 and 60 rotatably supports both end portions of the output shaft 34 in the axial direction.

  The external gear 22 is rotatably supported on the eccentric shaft 36 via a bearing 62 which is an example of a second bearing. As shown in FIG. 2, a plurality of external teeth 22 </ b> A are formed on the outer peripheral surface of the external gear 22. The external gear 22 has a plurality of conductive holes 64 arranged in the rotational direction. As shown in FIG. 1, the external gear 22 is housed in the housing recess 52 together with the internal gear 28 described later.

  As shown in FIG. 2, the carrier 24 integrally includes a plurality of inner pins 66 inserted into the plurality of conductive holes 64 in an eccentric state and a disc-shaped carrier body 68 that supports the plurality of inner pins 66. Have. The carrier body 68 is formed integrally with the other fixed shaft 14. As shown in FIG. 1, a bearing 70 is provided between the carrier main body 68 and the shaft portion 36A. Further, as shown in FIG. 2, the carrier 24 is formed with a through hole 72 that is coaxial with some of the plurality of inner pins 66 and penetrates in the axial direction of the inner pins 66. Has been.

  On the other hand, a plurality of press-fitting holes 74 into which the respective distal end portions of the plurality of inner pins 66 are press-fitted (light press-fitting) are formed in the second housing 42 facing the carrier body 68. A screw hole 74A (see FIG. 1) is formed in the press-fit hole 74 located coaxially with the through-hole 72 among the plurality of press-fit holes 74. The carrier main body 68 and the second housing 42 are fixed to each other by inserting a bolt 76 through the through hole 72 and screwing the tip of the bolt 76 into the screw hole 74A. The through-hole 72 only needs to be formed in at least one of the plurality of inner pins 66. Further, the screw hole portion 74 </ b> A may be formed in all of the plurality of press-fitting holes 74.

  In addition, as the tip of the bolt 76 is screwed into the screw hole 74A in this way, the tip of each of the plurality of inner pins 66 is press-fitted into the plurality of press-fitting holes 74. The respective distal ends of the inner pins 66 are fixed to the second housing 42.

  The hub 26 includes a substantially cylindrical case 78 and a cover 80 that closes an opening located on the other fixed shaft 14 side among the openings formed in the case 78. The case 78 houses the rotor 16, the stator 18, the motor housing 20, the carrier 24, the external gear 22, the internal gear 28, and the like. In addition, a bearing housing portion 82 is formed in an opening located on the one fixed shaft 12 side among the openings formed in the case 78, and the bearing housing portion 82 is an example of a third bearing. The bearing 84 which is is accommodated. The bearing 84 rotatably supports the case 78 with respect to the above-described spacer 46 fixed to the one fixed shaft 12 so as to be integrally rotatable.

  On the other hand, a bearing housing portion 86 is formed at the center of the cover 80, and a bearing 88 that is an example of a third bearing is housed in the bearing housing portion 86. The bearing 88 rotatably supports the cover 80 with respect to the carrier 24 formed integrally with the other fixed shaft 14. Further, as shown in FIG. 3, the cover 80 is provided with a coupling portion 90 for coupling the cover 80 and the internal gear 28 at a position radially outward from the internal gear 28. The coupling portion 90 includes an annular portion 90A that is formed in an annular shape, and a plurality of protruding portions 90B that protrude radially outward from the annular portion 90A.

  The internal gear 28 forms a speed reduction mechanism together with the external gear 22 and the carrier 24 described above, and functions as the final stage of the speed reduction mechanism. The internal gear 28 has a plurality of internal teeth 28 </ b> A on the inner peripheral surface of the inner portion in the axial direction (see FIG. 5), and the external gear 22 is in mesh with the internal gear 28. .

  As shown in FIGS. 4 and 5, the internal gear 28 is provided with a connecting portion 29 that connects the internal gear 28 and the cover 80 (hub 26). Specifically, the connecting portion 29 is axially outer than the internal teeth 28A forming the gear portion of the internal gear 28, that is, the side surface side of the hub 26 along the axial direction of the rotor 16 (the outer surface of the cover 80). ).

  The connecting portion 29 is made of a material different from that of the internal gear 28, and has a strength different from that of the internal gear 28. Specifically, the connecting portion 29 is made of a material having a lower strength than the internal gear 28. Specifically, for example, the internal gear 28 is made of a metal material, whereas the connecting portion 29 is made of a resin material. Moreover, the connection part 29 is integrally formed with the internal gear 28 by insert molding.

  The connecting portion 29 includes an annular portion 29A that is formed in an annular shape, and a plurality of protruding portions 29B that protrude radially outward from the annular portion 29A. Each projecting portion 29B is disposed so as to overlap the projecting portion 90B of the coupling portion 90, and the coupling portion 29 and the coupling portion 90 are coupled by a bolt 92, whereby the internal gear 28 and the cover 80 (hub) are connected. 26) are connected. Further, the cover 80 is fixed to the case 78 with bolts 94.

  In the drive unit 10, when the output shaft 34 is rotated together with the rotor 16, the eccentric shaft 36 is rotated, whereby the meshing position between the internal gear 28 and the external gear 22 is changed. The hub 26 is rotated together with the internal gear 28. That is, the rotation from the rotor 16 is decelerated by the speed reduction mechanism (the internal gear 28, the external gear 22 and the carrier 24), and the decelerated rotation is transmitted to the cover 80 (via the connecting portion 29 and the coupling portion 90). To the hub 26).

  Here, in the present embodiment, the connection part 29 is formed with a connection release part 35 capable of releasing the connection of the internal gear 28 and the cover 80 (hub 26) by the connection part 29 by breaking. Specifically, the connection release part 35 is made weak by the width (circumferential length) being reduced by the notch 27 formed between the annular part 29A and the protruding part 29B of the connection part 29. It is considered a vulnerable part. As a result, when a predetermined torque is applied between the annular portion 29A and the protruding portion 29B of the connecting portion 29, it breaks between them. The predetermined torque is set by the size of the cutout 27, the material strength of the connecting portion 29, the strength difference between the connecting portion 29 and the internal gear 28, and the like.

  As shown in FIGS. 1 and 2, in the drive unit 10, one fixed shaft 12, first bearings 56 and 60 (see FIG. 1), rotor 16, stator 18, motor housing 20, and spacer. 46 (see FIG. 1) are assembled together to form a motor assembly 96. Further, the eccentric shaft 36, the bearing 62, the bearing 70, and the external gear 22 are assembled together to constitute a gear assembly 98. Further, as shown in FIGS. 1 and 3, the cover 80, the bearing 88, and the internal gear 28 are assembled together to form the cover assembly 100.

  The drive unit 10 is assembled in the following manner, for example. That is, first, the motor assembly 96, the gear assembly 98, and the cover assembly 100 are each assembled.

  Subsequently, the bolt 76 is inserted into the through-hole 72, and the tip of the bolt 76 is screwed into the screw hole 74A, whereby the carrier body 68 and the second housing 42 are fixed to each other. At this time, the front end portions of the plurality of inner pins 66 are press-fitted into the plurality of press-fitting holes 74 as the front end portions of the bolts 76 are screwed into the screw hole portions 74 </ b> A.

  Further, the bearing 84 is assembled to the bearing housing 82 and the motor assembly 96 is assembled to the case 78 before and after the assembly of the carrier body 68 to the second housing 42. In this state, the cover 80 is fixed to the case 78 with the bolt 94. The drive unit 10 is assembled in the manner described above.

  Next, the operation and effect of one embodiment of the present invention will be described.

  According to the drive unit 10 according to the present embodiment, when the rotor 16 and the speed reduction mechanism (the internal gear 28, the external gear 22 and the carrier 24) are locked for some reason, the connection release portion formed in the connection portion 29. When 35 is broken, the connection by the connecting portion 29 between the internal gear 28 and the cover 80 (hub 26) is released. Thereby, since the internal gear 28 idles with respect to the hub 26 (cover 80, coupling | bond part 90) in the inner peripheral side of the cyclic | annular part 90A of the coupling | bond part 90, the lock | rock of a wheel can be prevented.

  Further, according to the drive unit 10, since the connecting portion 29 and the internal gear 28 are made of different materials, distortion is likely to occur between the connecting portion 29 and the internal gear 28. Compared with the case where the internal gear 28 and the internal gear 28 are made of the same material, the connection release portion 35 is easily broken, so that the internal gear 28 and the hub 26 can be easily disconnected.

  Further, according to the drive unit 10, the connecting portion 29 is made of a resin material whose strength is lower than that of the internal gear 28, while the internal gear 28 is made of a metal material. . For this reason, it becomes easy to make the connection cancellation | release part 35 fracture | rupture, maintaining the intensity | strength of the internal gear 28. FIG.

  Further, according to the drive unit, the connecting portion 29 and the internal gear 28 are integrally formed by insert molding, so that the connecting portion 29 and the internal gear 28 are connected as compared with the case where the connecting portion 29 and the internal gear 28 are formed separately. The handling of the part 29 is simple.

  Moreover, according to the drive unit 10, since the connection release part 35 is comprised by the weak part weakened by the notch 27 formed between the annular part 29A and the protrusion part 29B of the connection part 29, The connection release part 35 can be comprised, without adding components.

  Further, a coupling portion 90 that couples the cover 80 and the internal gear 28 is provided on the outer side in the radial direction from the internal gear 28, whereby force transmitted from the internal gear 28 to the cover 80 (hub 26). A long moment length is secured. Thereby, for example, the configuration of the coupling portion 90 can be simplified.

  Next, a modification of one embodiment of the present invention will be described.

  In the present embodiment, the connecting portion 29 and the internal gear 28 are made of different materials, but may be made of the same material.

  In the present embodiment, the connecting portion 29 is made of a material having a lower strength than the internal gear 28, but may be made of a material having a higher strength than the internal gear 28.

  Moreover, in this embodiment, although the connection part 29 was integrally formed with the internal gear 28 by insert molding, you may form separately.

  Further, in the present embodiment, the connecting portion 29 is disposed so as to be shifted outward in the axial direction from the internal teeth 28A forming the gear portion of the internal gear 28, but overlaps the internal teeth 28A in the axial direction. May be arranged.

  Further, in the present embodiment, the connection release portion 35 is a weakened portion made weak by the notch 27 formed in the connecting portion 29. For example, in addition to or instead of the notch 27, the connecting portion It may be formed by making 29 thin.

  Further, the case 78 is rotatably supported by the spacer 46 via the bearing 84, but may be rotatably supported by the one fixed shaft 12 via the bearing 84.

  Similarly, the cover 80 is rotatably supported by the carrier 24 via the bearing 88, but may be rotatably supported by the other fixed shaft 14 via the bearing 88.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and other various modifications can be made without departing from the spirit of the present invention. It is.

DESCRIPTION OF SYMBOLS 10 ... Drive unit, 16 ... Rotor, 18 ... Stator, 22 ... External gear (deceleration mechanism), 24 ... Carrier (deceleration mechanism), 26 ... Hub, 27 ... -Notch, 28 ... Internal gear (final stage of reduction mechanism), 28A ... Internal gear (gear part), 29 ... Connection part, 35 ... Connection release part

Claims (6)

A rotor supported rotatably;
A stator provided on the radially outer side of the rotor for rotating the rotor;
A speed reduction mechanism that decelerates rotation from the rotor;
A connecting portion for connecting the final stage of the speed reduction mechanism and a wheel hub, and transmitting the rotation decelerated by the speed reduction mechanism to the wheel hub;
A connection release portion formed in the connection portion and capable of releasing the connection by the connection portion between the final stage of the speed reduction mechanism and the wheel hub by breakage;
Electric bicycle drive unit equipped with.   2. The electric bicycle drive unit according to claim 1, wherein the connecting portion is made of a material different from that of the final stage of the speed reduction mechanism.   The drive unit of the electric bicycle according to claim 2, wherein the connecting portion is made of a material having a lower strength than a final stage of the speed reduction mechanism. The final stage of the speed reduction mechanism is made of a metal material,
The electric bicycle drive unit according to claim 3, wherein the connecting portion is made of a resin material.   The electric bicycle drive unit according to claim 4, wherein the connecting portion is formed integrally with the final stage of the speed reduction mechanism by insert molding.   The drive unit of the electric bicycle according to any one of claims 1 to 5, wherein the connection release part is configured by a weak part weakened by a notch formed in the connection part.