JP2014051109A - Dynamo for bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamo for a bicycle capable of suppressing the weight increase of wheels, preventing the falling of a magnet, and facilitating the manufacturing and machining of the magnet.SOLUTION: A dynamo for a bicycle has a yoke portion 18 rotatable with a wheel 3; and an iron core portion 19 fixed to a hub shaft 15. The iron core portion 19 has first and second iron cores 21 and 22; and a magnet 23 having two poles and a coil 24 which are sandwiched between both iron cores 21 and 22. The first and second iron cores 21 and 22 have a plurality of first and second pole pieces 21a and 22a at predetermined intervals in a circumferential direction. The first and second pole pieces 21a and 22a are opposite to each other while keeping a predetermined gap 29 in a diametrical direction. The yoke portion 18 has a plurality of yoke pole pieces 18a at predetermined intervals in the circumferential direction. The yoke pole pieces 18a can freely enter/leave from spaces between the first pole pieces 21a and the second pole pieces 22a in a rotating direction of the wheel 3.

Description

  The present invention relates to a dynamo provided in a bicycle.

  Conventionally, as this kind of bicycle dynamo, for example, Patent Document 1 below discloses a permanent magnet, two stator cores, a coil, and the like provided inside a hub body of a bicycle front wheel.

  According to this, since the parts constituting the dynamo are built into the hub body, when exchanging the dynamo, it is necessary to disassemble the hub body after removing the front wheel, which is troublesome.

  As a solution to this, there is a hub dynamo 103 provided between the front wheel 101 and the front fork 102 of the bicycle as shown in FIG. In the hub dynamo 103, a fixed housing 104 is fixed to an axle 106 by a lock nut 105, and a coil 107 is disposed inside the fixed housing 104. Further, a rotation side housing 109 is attached to the spoke 108 of the front wheel 101, and a magnet 110 is provided inside the rotation side housing 109.

  The coil 107 is formed in an annular shape so as to surround the axle 106. In addition, the magnet 110 has a multipolar structure in which a plurality of magnet pieces in which the N pole and the S pole are polarized and magnetized are fixed in an annular shape so that the polarities of adjacent magnet pieces are different from each other. It arrange | positions so that the outer peripheral side of the coil 107 may be surrounded.

  According to this, when the front wheel 101 rotates, it rotates around the coil 107 with the magnet 110 fixed together with the front wheel 101, and the magnetic flux acting on the coil 107 changes, so that an electromotive force is generated in the coil 107 due to electromagnetic induction. Current flows.

  The hub dynamo 103 configured as described above is described in Patent Document 2 below.

Japanese Patent No. 3963634 Japanese Patent Laid-Open No. 10-108428

  However, in the hub dynamo 103 shown in FIG. 15, since the magnet 110 is arranged in an annular shape so as to surround the outer peripheral side of the coil 107, the outer diameter of the magnet 110 is increased and the weight is increased. Since the heavy magnet 110 is attached to the front wheel 101 in this way, there is a problem that the weight of the front wheel 101 increases and the pedal effort during driving increases. In addition, since the magnet 110 rotates integrally with the front wheel 101, the magnet 110 may fall off the rotation side housing 109 due to vibration caused by rotation.

Further, since the magnet 110 has a multipolar structure in which a plurality of magnet pieces are fixed in an annular shape, the structure of the magnet 110 is complicated, and there is a problem that manufacturing and processing of the magnet 110 are time-consuming.
An object of the present invention is to provide a bicycle dynamo that can suppress an increase in weight of a wheel, can prevent a magnet from falling off, and is easy to manufacture and process a magnet.

To achieve the above object, the first invention is a bicycle dynamo provided between a wheel and a fork in the axial direction of a hub shaft,
A yoke part attached to the wheel side and rotatable with the wheel; and an iron core part fixed to the hub axle side of the wheel;
The iron core portion includes first and second iron cores facing each other in the axial direction of the hub shaft, and a cylindrical two-pole magnet and coil sandwiched and fixed between the two iron cores,
The magnet has an N-pole abutting on one of the first and second iron cores, an S-pole abutting on the other iron core of the first and second iron cores,
The first iron core has a plurality of first pole pieces formed at predetermined intervals in the circumferential direction,
The second iron core has a plurality of second pole pieces formed at predetermined intervals in the circumferential direction,
The first pole piece and the second pole piece are opposed to each other with a predetermined gap in the radial direction of the wheel,
The yoke portion has a plurality of yoke pole pieces formed at predetermined intervals in the circumferential direction,
The yoke pole piece is inserted between the first pole piece and the second pole piece, and is freely accessible between the first pole piece and the second pole piece in the rotational direction of the wheel.

  According to this, when a wheel rotates, a yoke part rotates with a wheel, and a yoke pole piece goes in and out between a 1st pole piece and a 2nd pole piece in the rotation direction of a wheel. At this time, if the yoke pole piece enters between the first pole piece and the second pole piece according to the rotation of the wheel, the magnetic flux of the magnet passes from the N pole to the first iron core and passes through the first pole piece. It reaches the second pole piece through the yoke pole piece from the piece, and reaches the S pole through the second iron core.

  Further, when the yoke pole piece is retracted from between the first pole piece and the second pole piece according to the rotation of the wheel, the yoke pole piece is present between the first pole piece and the second pole piece. Since the gap is not formed, the magnetic flux of the magnet is interrupted between the first pole piece and the second pole piece, and hardly passes from the first pole piece to the second pole piece.

  In this way, the state in which the magnetic flux reaches the S pole through the pole pieces from the N pole of the magnet and the state where the magnetic flux is interrupted and does not reach the coil alternately occurs according to the rotation of the wheel. Electric current is generated and generated.

  Since the magnet is not provided on the wheel side and is fixed by being sandwiched between the first iron core and the second iron core, an increase in the weight of the wheel can be suppressed. Further, since the magnet is sandwiched and fixed between the first iron core and the second iron core, the magnet does not rotate with the wheel, and the magnet can be prevented from falling off. Further, since a cylindrical dipole magnet is used, it is not necessary to make the magnet a multipolar structure with more than two poles, the magnet structure is simplified, and the magnet can be easily manufactured.

In the bicycle dynamo in the second invention, the first and second iron cores are disk-shaped members having different outer diameters,
The first pole piece is formed on the outer periphery of the first iron core,
The second pole piece is formed on the outer periphery of the second iron core,
The hub axle is inserted through the first and second iron cores,
The magnet is disposed so as to surround the hub shaft at a radially inner side than the first and second pole pieces,
The coil is disposed between the magnet and the first and second pole pieces in the radial direction.

The bicycle dynamo in the third invention is formed by bending the first pole piece from the outer peripheral portion of the first iron core toward the axial center of the hub shaft,
The second pole piece is formed by being bent from the outer peripheral portion of the second iron core in the axial direction of the hub shaft,
The yoke pole piece is formed by being bent from the inner peripheral portion of the annular yoke portion toward the axial center of the hub shaft,
The same number of first pole pieces, second pole pieces, and yoke pole pieces are formed.

The bicycle dynamo according to the fourth aspect of the present invention is such that a cover that covers the outside is provided on the iron core.
According to this, the outer side of the iron core is protected by the cover.

  As described above, according to the present invention, the magnet is not provided on the wheel side and is fixed by being sandwiched between the first iron core and the second iron core. it can. As a result, the pedal effort during travel is reduced.

  Further, since the magnet does not rotate with the wheel, it is possible to prevent the magnet from falling off. Furthermore, since a cylindrical bipolar magnet is used, it is not necessary to make the magnet a multipolar structure with more than two poles, the magnet structure is simplified, and the magnet can be easily manufactured and processed.

Front side view of a bicycle equipped with a bicycle dynamo in an embodiment of the present invention Cross section of bicycle dynamo Same as above, side view of bicycle dynamo (view along arrow XX in FIG. 2) YY arrow view in FIG. Cross section of the iron core part of the bicycle dynamo XX arrow view in FIG. YY arrow view in FIG. Sectional view of yoke part of bicycle dynamo XX view in FIG. The enlarged view which shows the state which the yoke pole piece of the dynamo for bicycles has penetrated between the 1st pole piece and the 2nd pole piece XX arrow view in FIG. The enlarged view which shows the state which the yoke pole piece of the bicycle dynamo has withdrawn from between the 1st pole piece and the 2nd pole piece XX arrow view in FIG. Same as above, graph of flux linkage and electromotive force of Dynamo for bicycle Cross-sectional view of a conventional bicycle dynamo

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, reference numeral 1 denotes a bicycle, a front hawk 2 (an example of a hawk), a front wheel 3 (an example of a wheel), a headlamp 4 attached to the front hawk 2, and a headlamp 4. It has a dynamo 5 and the like for supplying electric power.

  The headlamp 4 is equipped with a light sensor and a vibration sensor, and is configured to automatically turn on the headlamp 4 based on the detection of the light sensor when the surroundings become dark during traveling. The front hawk 2 has a pair of left and right hawk legs 7. The front wheel 3 includes a hub 9 provided at the center of rotation, a plurality of spokes 10 provided radially from the hub 9, an annular rim 11 provided at the outer peripheral end of the spoke 10, and a rim 11. The tire 12 is fitted externally.

  As shown in FIG. 2, the hub 9 includes a cylindrical hub body 14 having collars 13 at both ends, and a hub shaft 15 inserted through the hub body 14. The hub body 14 is rotatably supported by the hub shaft 15 via a bearing. The hub shaft 15 is attached and fixed between the lower end portions of both fork legs 7 of the front fork 2 by hub nuts 16 screwed to both ends. Thereby, the front wheel 3 is rotatably attached to the front fork 2.

  The dynamo 5 is provided between the front wheel 3 and the front fork 2 in the axial direction A of the hub shaft 15, that is, between any one of the flanges 13 of the hub 9 and the lower part of the one fork foot 7. The dynamo 5 includes a yoke portion 18 that is attached to the front wheel 3 side and is rotatable with the front wheel 3, and an iron core portion 19 that is fixed to the hub shaft 15 side.

  As shown in FIGS. 2 and 5 to 7, the iron core portion 19 is sandwiched between the first and second iron cores 21 and 22 opposed in the axial direction A, and both the iron cores 21 and 22. A fixed permanent magnet 23 and a coil 24 are provided. Among these, the 1st iron core 21 is a disk-shaped member which has the through-hole 26 in the center part, and has the some 1st pole piece 21a in the outer peripheral part. These first pole pieces 21 a are provided in a comb shape at predetermined intervals in the circumferential direction, and are bent inward in the axial direction A from the outer peripheral portion of the first iron core 21.

  Moreover, the 2nd iron core 22 is a disk-shaped member which has the through-hole 28 in the center part, and has the some 2nd pole piece 22a in the outer peripheral part. These second pole pieces 22 a are provided in a comb shape at predetermined intervals in the circumferential direction, and are bent outward in the axial direction A from the outer peripheral portion of the second iron core 22.

  The outer diameter of the second iron core 22 is smaller than the outer diameter of the first iron core 21, and the second pole piece 22 a is disposed inward of the first pole piece 21 a in the radial direction B of the front wheel 3. The pole piece 21a and the second pole piece 22a are positioned so as to oppose and overlap each other with a predetermined gap 29 in the radial direction B.

  One end portion of the hub shaft 15 is inserted into both through holes 26 and 28 of the first and second iron cores 21 and 22, and is sandwiched between the lower portion of one of the fork legs 7 and the first iron core 21 so as to be hub shaft. The first and second iron cores 21 and 22 are fixed to the hub shaft 15 by an iron core fixing nut 30 that is screwed to one end of 15. The iron core fixing nut 30 is processed with a non-magnetic material that suppresses leakage magnetic flux.

  Between the outer peripheral surface of one end of the hub shaft 15 and the inner peripheral surfaces of the through holes 26 and 28, an annular iron core washer 31 processed with a nonmagnetic material that suppresses leakage magnetic flux is fitted. Yes. The iron core washer 31 has a flange portion 31 a extending from the outer periphery to the outer side in the radial direction B over the entire periphery, and the flange portion 31 a is an inner peripheral portion of the first iron core 21 and an inner portion of the second iron core 22. It is sandwiched between the periphery.

  The permanent magnet 23 is formed in a cylindrical shape so as to surround the hub shaft 15 on the inner side in the radial direction B than the first and second pole pieces 21a and 22a. The permanent magnet 23 has a two-pole structure in which the outer surface in the axial direction A is N-pole and the inner back surface is S-pole, and the N-pole is in contact with the first iron core 21 (an example of one iron core). The S pole is in contact with the second iron core 22 (an example of the other iron core).

  The coil 24 is wound via a coil bobbin 33 and is disposed between the permanent magnet 23 and the first and second pole pieces 21a and 22a in the radial direction B. One end of the coil 24 is sandwiched between and electrically connected to the first iron core 21 or the second iron core 22, and is grounded to the vehicle body of the bicycle 1 via the hub shaft 15. As shown in FIGS. 5 and 6, the other end 24 a of the coil 24 is drawn to the outside of the first iron core 21 and connected to the output terminal 41. The output terminal 41 is attached to the coil bobbin 33 by a terminal attachment screw 42 and is insulated from the first iron core 21. The output terminal 41 and the headlamp 4 are electrically connected via a cord 43.

  As shown in FIGS. 2, 4, 8, and 9, the yoke portion 18 is attached to the spoke 10 of the front wheel 3 by one and the other mounting brackets 35 and 36 and a plurality of yoke mounting screws 37. Yes. The yoke portion 18 is an annular member, and has a plurality of yoke pole pieces 18a on the inner peripheral portion. The yoke pole pieces 18a are provided in a comb-like shape at predetermined intervals in the circumferential direction, and are bent outward from the inner circumference of the yoke portion 18 in the axial direction A to be first pole pieces 21a and second pole pieces 22a. 10 and 12, as shown in FIG. 10 and FIG. 12, in the rotational direction C of the front wheel 3, the first pole piece 21a and the second pole piece 22a can freely enter and exit.

  The yoke pole piece 18a, the first pole piece 21a, and the second pole piece 22a are respectively provided in the same number (same number of poles). As an example, in FIG. 7 and FIG. 9, 18 pole pieces (18 poles). 18a, 21a, and 22a are provided.

  Each of the one and the other mounting brackets 35 and 36 is an annular member, and is provided so as to sandwich the spoke 10 from both sides in the axial direction A. One mounting bracket 35 is fitted on the flange 13 of the hub body 14, and the yoke portion 18 is abutted against the one mounting bracket 35. The yoke portion 18 and one and the other mounting brackets 35 and 36 are connected and fixed by a yoke mounting screw 37.

  As shown in FIGS. 2 and 3, the first iron core 21 is provided with a cover 38 that covers the outer side in the axial direction A and the outer periphery of the first pole piece 21 a. The cover 38 is externally fitted to the iron core fixing nut 30 and sandwiched between the fork legs 7 of the front fork 2 and the first iron core 21, and the first iron core 21 is covered by a plurality of cover mounting screws 39. It is fixed to.

The cover 38 has a terminal cover portion 38a that covers the output terminal 41, and the cord 43 is connected to the output terminal 41 through a lower opening 38b of the terminal cover portion 38a.
Hereinafter, the operation of the above configuration will be described.

  When the bicycle 1 is run and the front wheel 3 rotates, as shown in FIGS. 10 to 13, the yoke portion 18 rotates together with the front wheel 3, and the yoke pole piece 18 a becomes the first pole in the rotation direction C of the front wheel 3. It goes in and out between the piece 21a and the second pole piece 22a. At this time, as shown in FIGS. 10 and 11, if the yoke pole piece 18 a enters between the first pole piece 21 a and the second pole piece 22 a according to the rotation of the front wheel 3, the permanent magnet 23. As indicated by the arrow, the magnetic flux of the second iron piece 22 passes through the first iron core 21 from the N pole and passes through the first pole piece 21a of the first iron core 21 and the yoke pole piece 18a. 22a, and reaches the S pole through the second iron core 22.

  Further, as shown in FIGS. 12 and 13, when the yoke pole piece 18a is retracted from between the first pole piece 21a and the second pole piece 22a in accordance with the rotation of the front wheel 3, the first pole A gap 29 in which the yoke pole piece 18a does not exist is formed between the piece 21a and the second pole piece 22a. For this reason, the magnetic flux of the permanent magnet 23 is interrupted between the first pole piece 21a and the second pole piece 22a, and hardly passes from the first pole piece 21a to the second pole piece 22a.

  Thus, according to the rotation of the front wheel 3, the magnetic flux reaches the S pole from the N pole of the permanent magnet 23 through the pole pieces 18 a, 21 a, 22 a (see FIGS. 10 and 11) and in the middle. Since the state of being blocked and not reaching (see FIGS. 12 and 13) alternately and repeatedly occurs, a current is generated in the coil 24 and power is generated. The current generated in the coil 24 in this way flows through the cord 43 and is supplied to the headlamp 4, and the headlamp 4 is automatically turned on according to the ambient brightness.

  FIG. 14A is a graph showing a change in linkage magnetic flux, and FIG. 14B is a graph showing a change in generated electromotive force. In FIG. 14A, the range D1 corresponds to the time when the yoke pole piece 18a enters between the first pole piece 21a and the second pole piece 22a as shown in FIGS. 10 and 11, and the range D2 Corresponds to when the yoke pole piece 18a is retracted from between the first pole piece 21a and the second pole piece 22a and the magnetic flux is interrupted as shown in FIGS. Further, as shown in FIG. 14B, since the electromotive force is generated due to the change of the linkage flux, it is generated with a deviation from the cycle of the linkage flux.

  As shown in FIG. 2, in the configuration of the dynamo 5, the permanent magnet 23 is not provided on the front wheel 3 and is fixed between the first iron core 21 and the second iron core 22. An increase in the weight of the front wheel 3 can be suppressed. As a result, the pedal effort during travel is reduced.

  Since the permanent magnet 23 is sandwiched and fixed between the first iron core 21 and the second iron core 22, the permanent magnet 23 does not rotate with the front wheel 3, and the permanent magnet 23 is removed. Can be prevented.

  Furthermore, since the cylindrical two-pole permanent magnet 23 is used, there is no need for the permanent magnet 23 to have a multipole structure with more than two poles, and the structure of the permanent magnet 23 is simplified, Easy to manufacture and process. Further, the cover 38 protects the outside of the iron core portion 19 including the output terminal 41.

  When exchanging the dynamo 5, first, both hub nuts 16 are removed from both ends of the hub shaft 15, and the front wheel 3 is removed from the front fork 2. Thereafter, the set of iron cores 19 can be removed from the hub shaft 15 by removing the iron core fixing nut 30 from the hub shaft 15. Further, by removing the yoke mounting screw 37, the yoke portion 18 and both mounting brackets 35 and 36 can be removed together from the front wheel 3. As a result, the dynamo 5 can be easily replaced.

  In the above embodiment, as shown in FIG. 2, the dynamo 5 is provided between the front wheel 3 and one fork foot 7 of the front fork 2, but between the rear wheel and one fork foot of the rear fork. May be provided.

  In the above embodiment, the N pole of the permanent magnet 23 is brought into contact with the first iron core 21 and the S pole is brought into contact with the second iron core 22. However, the N pole is brought into contact with the second iron core 22. The S pole may be brought into contact with the first iron core 21.

  In the above embodiment, as shown in FIG. 7 and FIG. 9, 18 yoke pole pieces 18a, first pole pieces 21a and second pole pieces 22a are provided (18 poles), respectively. It may be individual (multiple poles). In addition, since the power generation frequency increases as the number of pole pieces (number of poles) increases, flickering of the headlamp 4 during lighting can be suppressed.

  In the present invention, electricity generated by the dynamo is supplied to the headlamp, but may be supplied to an electrical device other than the headlamp (for example, a taillight).

1 Bicycle 2 Front Hawk (Hawk)
3 Front wheels
5 Dynamo 15 Hub shaft 18 Yoke part 18a Yoke pole piece 19 Iron core part 21 First iron core 21a First pole piece 22 Second iron core 22a Second pole piece 23 Permanent magnet 24 Coil 29 Air gap 38 Cover A Axial direction B Radial direction C Rotation direction

Claims (4)

A bicycle dynamo provided between a wheel and a fork in the axial direction of the hub shaft,
A yoke part attached to the wheel side and rotatable with the wheel; and an iron core part fixed to the hub axle side of the wheel;
The iron core portion includes first and second iron cores facing each other in the axial direction of the hub shaft, and a cylindrical two-pole magnet and coil sandwiched and fixed between the two iron cores,
The magnet has an N-pole abutting on one of the first and second iron cores, an S-pole abutting on the other iron core of the first and second iron cores,
The first iron core has a plurality of first pole pieces formed at predetermined intervals in the circumferential direction,
The second iron core has a plurality of second pole pieces formed at predetermined intervals in the circumferential direction,
The first pole piece and the second pole piece are opposed to each other with a predetermined gap in the radial direction of the wheel,
The yoke portion has a plurality of yoke pole pieces formed at predetermined intervals in the circumferential direction,
The yoke pole piece is inserted between the first pole piece and the second pole piece, and is freely accessible between the first pole piece and the second pole piece in the rotation direction of the wheel. Dynamo. The first and second iron cores are disk-shaped members having different outer diameters,
The first pole piece is formed on the outer periphery of the first iron core,
The second pole piece is formed on the outer periphery of the second iron core,
The hub axle is inserted through the first and second iron cores,
The magnet is disposed so as to surround the hub shaft at a radially inner side than the first and second pole pieces,
The bicycle dynamo according to claim 1, wherein the coil is arranged between the magnet and the first and second pole pieces in the radial direction. The first pole piece is formed by being bent from the outer peripheral portion of the first iron core in the axial direction of the hub shaft,
The second pole piece is formed by being bent from the outer peripheral portion of the second iron core in the axial direction of the hub shaft,
The yoke pole piece is formed by being bent from the inner peripheral portion of the annular yoke portion toward the axial center of the hub shaft,
The bicycle dynamo according to claim 1 or 2, wherein the same number of first pole pieces, second pole pieces, and yoke pole pieces are formed. The bicycle dynamo according to any one of claims 1 to 3, wherein a cover that covers the outside is provided on the iron core.

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