Power generator

Abstract

To provide a power generator that can generate power with a simple structure.SOLUTION: A power generator 10 comprises: a bracket 33; a crank shaft 4 accommodated in the bracket 33; one or more bearings 32 rotatably supporting the crank shaft 4 with respect to the bracket 33; and a stator 34 supported on the bracket 33. A magnet 311 is fixed to a side face of the crank shaft 4.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power generation device. [Background technology]

[0002] Patent Document 1 discloses a bottom bracket structure for a bicycle having an electricity generating mechanism. In this bottom bracket structure, a crankshaft is connected to a rotating part of the electricity generating mechanism via a planetary gear unit. The planetary gear unit allows the rotating part of the electricity generating mechanism to rotate faster than the crankshaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-15987 A Summary of the Invention [Problem to be solved by the invention]

[0004] The bottom bracket structure of Patent Document 1 incorporates a complex planetary gear unit and power generation mechanism in order to obtain sufficient power generation performance. Such a bottom bracket structure is costly due to its complex structure. In addition, there is a concern about the increase in weight due to the incorporation of the planetary gear unit, etc.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a power generating device capable of generating power with a simple structure. [Means for solving the problem]

[0006] A generator according to one embodiment of the present invention comprises a bracket, a crankshaft housed in the bracket, one or more bearings that rotatably support the crankshaft relative to the bracket, and a stator supported by the bracket, and a magnet is fixed to a side of the crankshaft. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view showing a schematic structure of a crankset 1 incorporating a power generating device according to an embodiment of the present invention. [Diagram 2] 1 is an exploded perspective view showing a schematic structure of a crankset 1 incorporating a power generating device according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. [Figure 4] 4 is a cross-sectional perspective view of the bottom bracket 3 and the crankshaft 4 taken along the cross section of FIG. 3. FIG. [Diagram 5] FIG. 2 is an exploded perspective view of the bottom bracket 3 and the crankshaft 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a schematic structure of a crankset 1 incorporating a power generating device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a schematic structure of a crankset 1 incorporating a power generating device according to an embodiment of the present invention. This crankset 1 is mounted on a bottom bracket shell 2 of a frame of, for example, a bicycle (including all types of bicycles such as road bikes, cross bikes, mountain bikes, and city bikes). For the sake of simplification, only the bottom bracket shell 2 of the frame that defines a cylindrical internal space is shown in FIG. 1 and FIG. 2. Although the bottom bracket shell 2 is shown to have a cylindrical outer shape, it is not limited to this shape and may have other shapes.

[0009] The crankset 1 includes a bottom bracket 3, a crankshaft 4, a right crank arm 5, a left crank arm 6, and a chain ring 7. The bottom bracket 3 is attached to a bottom bracket shell 2. The internal space of the bottom bracket shell 2 is opened through circular openings 21 and 22. The crankshaft 4 is supported by the bottom bracket 3 so as to be rotatable around an axis x. Most of the crankshaft 4 is housed within the bottom bracket 3, and one end 41 and the other end 42 of the crankshaft 4 protrude from the bottom bracket 3 in a direction along the axis x (hereinafter referred to as the "rotation axis direction"). The crankshaft 4, the right crank arm 5, and the left crank arm 6 are formed, for example, from a metal material.

[0010] The right crank arm 5 has a main body 51, a hole or mounting hole 52 formed in the main body 51 along the axis x, a plurality of portions (hereinafter referred to as "projections") 53 projecting from the main body 51 in a radial direction perpendicular to the axis x, and one arm main body 54 similarly projecting radially from the main body 51. In this example, the chain ring 7 is attached to the inside of the main body 51 in the direction of the rotation axis. During attachment, a fastening part or bolt 72 is screwed into a hole or screw hole 55 formed in the projecting portion 53 through a hole or through hole 71 formed in the chain ring 7. In this example, four screw holes 55 and four through holes 71 are formed in the right crank arm 5 and the chain ring 7 at predetermined angular intervals around the axis x.

[0011] As is clear from Fig. 2, a sawtooth groove 43, for example, is formed on the outer peripheral surface of one end 41 of the crankshaft 4, while a sawtooth groove (not shown) is also formed on the inner peripheral surface of the mounting hole 52 of the right crank arm 5. The groove 43 and the groove of the mounting hole 52 extend parallel to the axis x. These grooves 43 fit together, so that the right crank arm 5 is attached to the one end 41 of the crankshaft 4 so as to be unable to rotate relative to each other. Note that the right crank arm 5 may incorporate a mechanism (not shown) for preventing the crankshaft 4 from falling off the right crank arm 5. A pedal (not shown) is attached to the tip of an arm body 54 extending from a base end connected to the body 51.

[0012] On the other hand, the left crank arm 6 has an arm body 61 and a hole, i.e., a mounting hole 62, formed at the base end of the arm body 61. For example, a sawtooth groove 44 is formed on the outer peripheral surface of the other end 42 of the crankshaft 4, while a sawtooth groove (not shown) is also formed on the inner peripheral surface of the mounting hole 62 of the left crank arm 6. These grooves 44 extend parallel to the axis x. The groove 44 and the groove of the mounting hole 62 are fitted together, so that the left crank arm 6 is mounted to the other end 42 of the crankshaft 4 so as not to rotate relative to the left crank arm 6. Note that the left crank arm 6 may be incorporated with a mechanism (not shown) for preventing the crankshaft 4 from falling off the left crank arm 6. A pedal (not shown) is attached to the tip of the arm body 61 extending from the base end where the mounting hole 62 is formed.

[0013] FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1. FIG. 4 is a cross-sectional perspective view of the bottom bracket 3 and the crankshaft 4 taken along the cross section of FIG. 3. FIG. 5 is an exploded perspective view of the bottom bracket 3 and the crankshaft 4. Note that the bottom bracket shell 2 is omitted in FIG. 5. Referring to FIGS. 3 to 5 together, the bottom bracket 3 has a rotor 31, one or more (two in this example) bearings 32, 32, a bracket 33, and a stator 34. Each bearing 32 is, for example, a ball bearing. The rotor 31 is attached to the crankshaft 4, while the stator 34 is attached to the bracket 33. The two bearings 32, 32 support the rotor 31 so as to be rotatable relative to the bracket 33 and the stator 34.

[0014] The rotor 31 has a magnet 311 fixed to a cylindrical outer circumferential side surface 45 centered on the axis x of the crankshaft 4 described above. For example, an adhesive or the like is used for fixing. The magnet 311 is, for example, a permanent magnet. The magnet 311 is formed in a cylindrical shape centered on the axis x as a whole. The magnet 311 is attached to the outer circumferential side surface 45 by combining, for example, two or more parts divided around the axis x. In this example, the magnet 311 is embedded in a recess 46 formed in the outer circumferential side surface 45 of the crankshaft 4. The recess 46 is recessed from the outer circumferential side surface 45 in an annular shape around the axis x.

[0015] In the radial direction, the outer diameter of the cylindrical outer peripheral side surface 311a of the magnet 311 centered on the axis x coincides with the outer diameter of the outer peripheral side surface 45 of the crankshaft 4. In the crankshaft 4, the portion forming the recess 46 is formed thicker in the radial direction perpendicular to the axis x than the other portions, but this is not limited thereto. The portion forming the recess 46 may be thinner than the other portions or may have the same thickness. The outer peripheral side surface 45 of the crankshaft 4 is covered by a cylindrical cover 312 between the pair of bearings 32, 32. This cover 312 can prevent the magnet 311 from falling off and ensure the axial strength of the crankshaft 4. The cover 312 is formed of a resin material such as CFRP (carbon fiber reinforced plastic).

[0016] The inner ring of the bearing 32 is supported by the crankshaft 4. The inner ring of each bearing 32 is in contact with the right crank arm 5 or the left crank arm 6 in the rotation axis direction. A bracket 33 is attached to the outer ring of the bearing 32. The bracket 33 has a pair of outer sleeves (hereinafter referred to as "outer sleeves") 331, 331 and an inner sleeve (hereinafter referred to as "inner sleeve") 332. The outer sleeve 331 and the inner sleeve 332 are both formed in a generally cylindrical shape. The outer sleeves 331, 331 are fixed to the openings 21, 22 of the bottom bracket shell 2, respectively. Each outer sleeve 331 has a generally cylindrical portion (hereinafter referred to as "fitting portion") 331a that fits into the inner peripheral surface 23 of the bottom bracket shell 2, and a generally cylindrical portion (hereinafter referred to as "flange portion") 331b that protrudes radially outward from the fitting portion 331a.

[0017] The fitting portion 331a is formed in a generally cylindrical shape centered on the axis x. A thread groove (not shown) is cut on the outer peripheral surface of the fitting portion 331a. Meanwhile, a similar thread groove (not shown) is cut on the inner peripheral surface 23 of the bottom bracket shell 2 corresponding to the fitting portion 331a. In this manner, each outer peripheral sleeve 331 is attached to the bottom bracket shell 2 by screwing the fitting portion 331a into the inner peripheral surface 23 of the bottom bracket shell 2. Each flange portion 331b is disposed adjacent to the openings 21, 22 outside the internal space of the bottom bracket shell 2. An outer ring of the bearing 32 is attached to the inner peripheral surface of each flange portion 331b by press fitting, adhesive, or the like.

[0018] Grooves 331c are formed on the outer peripheral surface of the flange portion 331b at equal angular intervals around the axis x in parallel with the axis x (see Figs. 4 and 5). In this example, a plurality of grooves 331c are arranged at equal intervals around the axis x. A tool (not shown) is engaged with the grooves 331c when removing the outer peripheral sleeve 331 from the bottom bracket shell 2 or when attaching the outer peripheral sleeve 331 to the bottom bracket shell 2. The bottom bracket 3 is fixed to the bottom bracket shell 2 by fastening the thread groove of the outer peripheral sleeve 331 to the thread groove of the bottom bracket shell 2. In other words, the bottom bracket 3 is of a screw-in type. However, instead of the screw-in type, a press-in type bottom bracket that is press-fitted into the bottom bracket shell 2 may be used. In this case, the grooves 331c and thread grooves of the outer peripheral sleeve 331 are not necessary.

[0019] In the direction of the rotation axis, the ends of the inner sleeve 332 are fitted to the inner ends of the pair of outer sleeves 331. In this example, the outer peripheral surface of the inner sleeve 332 is fitted to the inner peripheral surface of the fitting portion 331a of the outer sleeve 331. A seal member 333 is sandwiched between the inner peripheral surface of the fitting portion 331a and the outer peripheral surface of the inner sleeve 332. This seal member 333 seals between the internal space of the inner sleeve 332 and the external space. A recess 332a is formed on the outer peripheral surface of the inner sleeve 332, which is recessed annularly toward the inner peripheral side in the radial direction. A stator 34 is supported by the recess 332a. In this example, the stator 34 has a cylindrical coil 341, for example, a copper wire, a cylindrical yoke, i.e., a stator core 342, and a stator housing 343.

[0020] The coil 341 is a so-called coreless coil, and is wound in the rotation axis direction and formed into an annular shape around the axis x as a whole. The internal space around which the coil 341 is wound is, for example, hollow. The coil 341 faces the magnet 311 in the radial direction with a predetermined magnetic gap. The coil 341 is surrounded by a cylindrical stator core 342 centered on the axis x. The stator core 342 surrounds the crankshaft 4. The stator core 342 is formed of a laminated body in which a plurality of annular silicon steel plates are laminated in the rotation axis direction. A cylindrical stator housing 343 centered on the axis x is disposed on the outer circumferential surface of the stator core 342. In this example, the stator core 342 is attached to the inner circumferential surface of the stator housing 343. An adhesive 344 is applied to the ends of the coil 341 and the stator core 342 on the left crank arm 6 side in the recess 332a.

[0021] At least the crankshaft 4, the rotor 31 (magnet 311), the bearing 32, the bracket 33 (the outer peripheral sleeve 331 and the inner peripheral sleeve 332), and the stator 34 (the coil 341 and the stator core 342) constitute the power generating device 10 according to the present invention. The power generating device 10 may further include a cover 312, a stator housing 343, or a seal member 333. In this power generating device 10, the stator 34, i.e., the coil 341 and the stator core 342, are positioned between the two bearings 32, 32 in the direction of the rotation axis. The outer diameter of the outer peripheral surface of the stator 34, i.e., the stator housing 343, is set to be equal to or smaller than the outer diameter of the outer peripheral surface of the fitting portion 331a of the outer peripheral sleeve 331 of the bracket 33.

[0022] The power generating device 10 has wiring (not shown) that bundles together a number of wires drawn from the coils 341. This wiring is drawn out to the outside of the bottom bracket 3, for example, from through holes or grooves (not shown) formed in the bracket 33, and is electrically connected to, for example, electronic devices mounted on the bicycle. Examples of the electronic devices include, for example, lights, electric shifts, electric brakes, a cycle computer, and various sensors. The various sensors include sensors that can communicate with the cycle computer, for example, using a predetermined wireless communication standard. The wiring drawn out from each coil 341 may be connected to, for example, an electrical component such as a capacitor with a power storage function.

[0023] When such a crankset 1 is installed in a bicycle, pedaling causes the right crank arm 5 and the left crank arm 6 to swing about the axis x. As a result, the crankshaft 4 rotates about the axis x. This rotation causes the rotor 31 and the stator 34 to rotate relative to each other. As a result, electrical energy is generated in the coil 341 due to magnetic interaction between the magnet 311 and the coil 341. The electrical energy thus generated is sent through wiring to electronic devices mounted on the bicycle. The electronic devices can be driven by this electrical energy. The electrical energy generated by the power generation device 10 may be temporarily stored in a power storage device such as a capacitor.

[0024] In the crankset 1 described above, the generator 10 is assembled in the bottom bracket shell 2. Specifically, the rotor 31 is fixed to the outer peripheral side surface 45 of the crankshaft 4, and the stator 34 is fixed to the bracket 33 that houses the crankshaft 4. In this way, the generator 10 can generate electricity with a simple structure. Since the generator 10 does not have a complex structure that can increase the weight, the increase in weight due to the assembly of the generator 10 can be suppressed. With the generator 10, it is not necessary to mount a battery on the bicycle. This relieves the user from the trouble of charging the battery. In addition, if a battery is already mounted, the battery capacity can be reduced to reduce the weight of the battery itself. Alternatively, the battery capacity can be kept the same, and the use of the electricity stored in the battery can be dedicated to assisting the bicycle, thereby increasing the range of the assisted bicycle itself.

[0025] Moreover, the coil 341 of the stator 34 is a so-called coreless coil, and is not wound around the stator core 342. As a result, the weight of the stator 34 can be reduced. Moreover, the generation of cogging torque due to magnetic interaction between the coil 341 and the magnet 311 can be suppressed. Also, since the magnet 311 is fixed to the recess 46 formed in the outer peripheral side surface 45 of the crankshaft 4, the outer diameter of the crankshaft 4 remains the same as before. Furthermore, the coil 341 and the stator core 342 are located between the two bearings 32, 32, and their outer diameters are set to be equal to or smaller than the outer diameter of the fitting portion 331a of the outer peripheral sleeve 331. Therefore, when the power generating device 10 is assembled, there is no need to change the design of the conventional bottom bracket shell 2.

[0026] Next, a scene in which the above-mentioned crankset 1 is mounted on the bottom bracket shell 2 will be described. First, the bottom bracket 3 is mounted on the bottom bracket shell 2. Specifically, two outer peripheral sleeves 331 to which bearings 32 are attached are fixed to the openings 21 and 22 of the bottom bracket shell 2, respectively. An inner peripheral sleeve 332 to which a stator 34 has been previously attached is supported on one of the outer peripheral sleeves 331. Then, the crankshaft 4, to which the right crank arm 5 to which the chain ring 7 has already been attached is previously attached at one end 41, is attached by insertion or the like into the bottom bracket 3. Then, the left crank arm 6 is attached to the other end 42 of the crankshaft 4. In this manner, the crankset 1 is mounted on the bottom bracket shell 2.

[0027] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is clear from the claims that such modifications or improvements can also be included in the technical scope of the present invention.

[0028] The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The components of the above-described embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those illustrated, and can be modified as appropriate. Furthermore, components shown in different embodiments can be partially substituted or combined with each other within the scope of technical inconsistency. [Explanation of symbols]

[0029] 1 crank set, 2 bottom bracket shell, 21 opening, 22 opening, 23 inner peripheral surface, 3 bottom bracket, 31 rotor, 311 magnet, 311a outer peripheral side surface, 312 cover, 32 bearing, 33 bracket, 331 outer peripheral sleeve (outer peripheral sleeve), 331a mating portion (mating portion), 331b protruding portion (flange portion), 331c groove, 332 inner peripheral sleeve (inner peripheral sleeve), 332a recess, 333 seal member, 34 stator, 341 coil, 342 yoke (stator core), 343 stator housing, 344 adhesive, 4 crankshaft, 41 one end, 42 other end, 43 groove, 44 groove, 45 outer peripheral side surface, 46 recess, 5 right crank arm, 51 main body, 52 hole (mounting hole), 53 protruding part (protruding part), 54 arm body, 55 hole (screw hole), 6 left crank arm, 61 arm body, 62 hole (mounting hole), 7 chain ring, 71 hole (through hole), 72 bolt, 10 generator, x-axis line

Claims

1. A bracket and A crankshaft accommodated in the bracket; and one or more bearings that rotatably support the crankshaft relative to the bracket; a stator supported by the bracket, A generator having a magnet fixed to a side surface of the crankshaft.

2. The power generating device according to claim 1 , wherein the stator comprises a cylindrical yoke surrounding the crankshaft, and a cylindrical coil surrounded by the yoke.

3. The power generating device according to claim 2 , wherein the coil is wound in a direction of a rotation axis.

4. The power generating device according to claim 1 , wherein the magnet is fixed to an outer circumferential side surface of the crankshaft.

5. The power generating device according to claim 1 , wherein the magnet is fixed to a recess in an outer circumferential side surface of the crankshaft.

6. A plurality of the bearings are provided, The power generating device according to claim 1 , wherein the magnet and the stator are positioned between the plurality of bearings in the rotation axis direction.

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