Power generation device

Abstract

A power generation device (10) is provided with: a bracket (33); a crankshaft (4) accommodated in the bracket (33); one or a plurality of bearings (32) for rotatably supporting the crankshaft (4) with respect to the bracket (33); and a stator (34) supported by the bracket (33). A magnet (311) is fixed to the side surface of the crankshaft (4).

Description

power generation equipment

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

[0002] Patent Document 1 discloses a bottom bracket structure for a bicycle with a generator mechanism. In this bottom bracket structure, a crankshaft is connected to a rotating part of the generator mechanism via a planetary gear unit. The planetary gear unit allows the rotating part of the generator mechanism to rotate at a higher speed than the crankshaft.

[0003] Japanese Patent Application Laid-Open No. 2006-15987

[0004] The bottom bracket structure of Patent Document 1 incorporates a complex planetary gear unit and power generation mechanism to achieve sufficient power generation performance. Such bottom bracket structures are costly due to their complex structure. There are also concerns about the increased weight caused by incorporating a planetary gear unit and other components.

[0005] Therefore, an example of an object of the present invention is to provide a power generating device that can generate power with a simple structure.

[0006] A power generating device according to a first aspect 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 fixed to a side of the crankshaft.

[0007] A power generating device according to a second aspect of the present invention includes a crank arm, a rotor fixed to the crank arm, a bracket, a stator fixed to the bracket, a bearing, and a crankshaft supported by the bracket via the bearing.

[0008] 1 is a perspective view schematically showing the structure of a crankset 1 incorporating a power generator according to a first embodiment of the present invention. FIG. 1 is an exploded perspective view schematically showing the structure of a crankset 1 incorporating a power generator according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view taken along line 3-3 of FIG. 1. FIG. 3 is a cross-sectional perspective view of the bottom bracket 3 and the crankshaft 4 taken along the cross section of FIG. 3. FIG. 4 is an exploded perspective view of the bottom bracket 3 and the crankshaft 4. FIG. 1 is a perspective view schematically showing the structure of a crankset 1A incorporating a power generator according to a second embodiment of the present invention. FIG. 1 is an exploded perspective view schematically showing the structure of a crankset 1A incorporating a power generator according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view taken along line 8-8 of FIG. 6. FIG. 8 is a partially enlarged cross-sectional view of a portion of the cross-sectional view of FIG. 8. FIG. 8 is a cross-sectional view taken along line 10-10 of FIG. 8. FIG. 11 is a perspective view schematically showing the structure of a crankset 1B incorporating a power generator according to a third embodiment of the present invention. FIG. 12 is an exploded perspective view schematically showing the structure of a crankset 1B incorporating a power generator according to the third embodiment of the present invention. FIG. 13 is a cross-sectional view taken along line 13-13 of FIG. 11. FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 13.

[0009] An embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically illustrating the structure of a crankset 1 incorporating a power generating device according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view schematically illustrating the structure of a crankset 1 incorporating a power generating device according to a first embodiment of the present invention. The crankset 1 is attached to a bottom bracket shell 2 of a bicycle frame (including all types of bicycles, such as road bikes, cross bikes, mountain bikes, and city bikes). For simplicity's sake, FIGS. 1 and 2 only illustrate the bottom bracket shell 2, which defines a cylindrical internal space within the frame. While the bottom bracket shell 2 is illustrated as having a cylindrical outer shape, it is not limited to this shape and may have other shapes.

[0010] 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 interior space of the bottom bracket shell 2 is open through circular openings 21 and 22. The crankshaft 4 is supported by the bottom bracket 3 so as to be rotatable about an axis x. Most of the crankshaft 4 is housed within the bottom bracket 3, with one end 41 and the other end 42 of the crankshaft 4 protruding from the bottom bracket 3 in a direction along the axis x (hereinafter referred to as the "rotational axis direction"). The crankshaft 4, right crank arm 5, and left crank arm 6 are made of, for example, a metal material.

[0011] The right crank arm 5 has a main body 51, a hole (i.e., mounting hole 52) formed in the main body 51 along the axis x, multiple portions (hereinafter referred to as "protrusions") 53 protruding from the main body 51 in a radial direction perpendicular to the axis x, and a single arm main body 54 similarly protruding radially from the main body 51. In this example, the chainring 7 is attached to the inside of the main body 51 in the rotation axis direction. For attachment, a fastening part (i.e., bolt 72) is screwed into a hole (i.e., screw hole 55) formed in the protrusion 53 and passes through a hole (i.e., through hole 71) formed in the chainring 7. In this example, four screw holes 55 and four through holes 71 are formed in the right crank arm 5 and the chainring 7, respectively, at predetermined angular intervals around the axis x.

[0012] 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, thereby attaching the right crank arm 5 to the one end 41 of the crankshaft 4 so as to prevent relative rotation. The right crank arm 5 may be equipped with 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.

[0013] On the other hand, the left crank arm 6 has an arm body 61 and a hole, i.e., an attachment hole 62, formed at the base end of the arm body 61. For example, sawtooth grooves 44 are formed on the outer peripheral surface of the other end 42 of the crankshaft 4, while sawtooth grooves (not shown) are also formed on the inner peripheral surface of the attachment hole 62 of the left crank arm 6. These grooves 44 extend parallel to the axis x. The grooves 44 and the grooves of the attachment hole 62 fit together, thereby attaching the left crank arm 6 to the other end 42 of the crankshaft 4 so as to prevent relative rotation. The left crank arm 6 may be equipped 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 attachment hole 62 is formed.

[0014] 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 crankshaft 4 taken along the cross section of FIG. 3. FIG. 5 is an exploded perspective view of the bottom bracket 3 and crankshaft 4. Note that the bottom bracket shell 2 is omitted from 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 rotatably support the crankshaft 4 with respect to the bottom bracket 3. That is, the bearings 32, 32 support the rotor 31 so that it can rotate relative to the bracket 33 and the stator 34.

[0015] The rotor 31 has a magnet 311 fixed to the cylindrical outer peripheral 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 peripheral 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 peripheral side surface 45 of the crankshaft 4. The recess 46 is recessed from the outer peripheral side surface 45 in an annular shape around the axis x.

[0016] 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 to this. The portion forming the recess 46 may be thinner than the other portions or may have the same thickness as the other portions. 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 prevents the magnet 311 from falling off and ensures the axial strength of the crankshaft 4. The cover 312 is formed of a resin material such as CFRP (carbon fiber reinforced plastic).

[0017] The inner ring of the bearing 32 is supported by the crankshaft 4. The inner ring of each bearing 32 contacts the right crank arm 5 or the left crank arm 6 in the direction of the rotation axis. 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 onto the inner circumferential 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.

[0018] The fitting portion 331a is formed in a generally cylindrical shape centered on the axis x. A thread groove (not shown) is cut into the outer peripheral surface of the fitting portion 331a. Meanwhile, a similar thread groove (not shown) is cut into the inner peripheral surface 23 of the bottom bracket shell 2 corresponding to the fitting portion 331a. In this way, each outer 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 positioned outside the internal space of the bottom bracket shell 2 and adjacent to the openings 21, 22. The outer ring of the bearing 32 is attached to the inner peripheral surface of each flange portion 331b by press fitting, adhesive, etc.

[0019] Grooves 331c are formed on the outer peripheral surface of the flange portion 331b at equal angular intervals around the axis x and parallel to the axis x (see FIGS. 4 and 5). In this example, multiple grooves 331c are arranged at equal intervals around the axis x. A tool (not shown) is engaged in these grooves 331c when removing or installing the outer sleeve 331 from the bottom bracket shell 2. The bottom bracket 3 is fixed to the bottom bracket shell 2 by tightening the thread grooves of the outer sleeve 331 into the thread grooves of the bottom bracket shell 2. In other words, the bottom bracket 3 is of a screw-in type. However, instead of a screw-in type, a press-fit 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 sleeve 331 are not necessary.

[0020] In the rotational axis direction, the ends of the inner peripheral sleeve 332 are fitted to the inner ends of the pair of outer peripheral sleeves 331. In this example, the outer peripheral surface of the inner peripheral sleeve 332 is fitted to the inner peripheral surface of the fitting portion 331a of the outer peripheral 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 peripheral sleeve 332. This seal member 333 seals the internal space of the inner peripheral sleeve 332 from the external space. A recess 332a is formed on the outer peripheral surface of the inner peripheral sleeve 332, recessed annularly radially inward. A stator 34 is supported in the recess 332a. In this example, the stator 34 includes a cylindrical coil 341, e.g., a copper wire, a cylindrical yoke or stator core 342, and a stator housing 343.

[0021] The coil 341 is a so-called coreless coil, wound in the rotational axis direction and formed into an annular shape around the axis x as a whole. The internal space around the coil 341 is, for example, hollow. The coil 341 faces the magnet 311 in the radial direction with a predetermined magnetic gap between them. 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 from a laminated body in which multiple annular silicon steel plates are stacked in the rotational axis direction. A cylindrical stator housing 343 centered on the axis x is disposed on the outer peripheral surface of the stator core 342. In this example, the stator core 342 is attached to the inner peripheral surface of the stator housing 343. Note that adhesive 344 is applied to the ends of the coil 341 and the stator core 342 on the left crank arm 6 side within the recess 332a.

[0022] At least the crankshaft 4, rotor 31 (magnet 311), bearing 32, bracket 33 (outer peripheral sleeve 331 and inner peripheral sleeve 332), and stator 34 (coil 341 and stator core 342) constitute the power generator 10 according to the present invention. The power generator 10 may further include a cover 312, a stator housing 343, or a seal member 333. In this power generator 10, the stator 34, i.e., the coil 341 and the stator core 342, are located 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.

[0023] The power generator 10 has wiring (not shown) that bundles together multiple wires drawn from the coils 341. This wiring is drawn to the outside of the bottom bracket 3, for example, 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 electronic devices include lights, electric shifters, electric brakes, a cycle computer, and various sensors. The various sensors include sensors that can communicate with the cycle computer using, for example, a predetermined wireless communication standard. The wiring drawn from each coil 341 may be connected to, for example, an electrical component such as a capacitor with a power storage function.

[0024] When such a crankset 1 is installed on 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, magnetic interaction between the magnet 311 and the coil 341 generates electrical energy in the coil 341. The electrical energy generated in this manner is sent via wiring to electronic devices mounted on the bicycle. The electronic devices can be powered 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.

[0025] In the crankset 1 described above, the generator 10 is installed inside the bottom bracket shell 2. Specifically, the rotor 31 is fixed to the outer peripheral 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. Because the generator 10 does not have a complex structure that could increase weight, the weight increase due to the installation of the generator 10 can be suppressed. With this generator 10, there is no need to install a battery on the bicycle. This eliminates the need for the bicycle to have a battery, eliminating the hassle of charging the battery. Furthermore, if a battery is already installed, the battery's weight can be reduced by reducing its capacity. Alternatively, the battery's capacity can be kept the same, and the stored electricity can be dedicated to assisting the bicycle, thereby increasing the range of the assisted bicycle itself.

[0026] Furthermore, 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. Furthermore, the generation of cogging torque due to magnetic interaction between the coil 341 and the magnet 311 can be suppressed. Furthermore, because the magnet 311 is fixed to a 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, no design changes to the conventional bottom bracket shell 2 are required when incorporating the power generating device 10.

[0027] Next, the installation of the crankset 1 described above into the bottom bracket shell 2 will be described. First, the bottom bracket 3 is attached to the bottom bracket shell 2. Specifically, two outer sleeves 331 with bearings 32 attached are fixed to the openings 21 and 22 of the bottom bracket shell 2, respectively. An inner sleeve 332 with a stator 34 already attached is supported by one of the outer sleeves 331. Next, the crankshaft 4, with the right crank arm 5 already attached to one end 41 and the chainring 7 already attached, is installed in the bottom bracket 3 by insertion or the like. Then, the left crank arm 6 is installed to the other end 42 of the crankshaft 4. In this manner, the crankset 1 is installed into the bottom bracket shell 2.

[0028] Fig. 6 is a perspective view schematically showing the structure of a crankset 1A incorporating a power generator according to a second embodiment of the present invention. Fig. 7 is an exploded perspective view schematically showing the structure of a crankset 1A incorporating a power generator according to the second embodiment of the present invention. This crankset 1A includes a bottom bracket 3A, a crankshaft 4, a right crank arm 5A, a left crank arm 6, and a chain ring 7. Compared to the crankset 1 described above, the structures of the bottom bracket 3A and the right crank arm 5A differ from those of the bottom bracket 3 and the right crank arm 5. Otherwise, the same components as those of the crankset 1 of the first embodiment described above are designated by the same reference numerals, and redundant description will be omitted here.

[0029] FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 6. Referring to FIGS. 6 to 8 together, the stator 8 is fixed to the bottom bracket 3A adjacent to the main body 51 of the right crank arm 5. Specifically, the stator 8 is fixed to the outer peripheral surface 331d of the flange portion 331b of the outer sleeve 331 of the bottom bracket 3. The outer peripheral surface 331d is defined by, for example, a cylindrical surface centered on the axis x. This outer peripheral surface 331d faces away from the inner peripheral surface 331e on the crankshaft 4 side. In this example, the side opposite the crankshaft 4 side is defined as the right crank arm 5A side. That is, the stator 8 is fixed to the outer peripheral surface 331d on the side of the right crank arm 5 opposite the crankshaft 4. Meanwhile, the bearing 32 is fixed to the inner peripheral surface 331e on the side of the crankshaft 4 opposite the right crank arm 5A.

[0030] A rotor 9 is disposed radially opposite the stator 8, perpendicular to the axis x. Specifically, as shown in FIGS. 7 and 8 , the rotor 9 is fixed to one side surface, i.e., the inner surface 51a, of the main body 51 of the right crank arm 5A, on the crankshaft 4 side in the direction of the rotation axis. In this example, the inner surface 51a extends, for example, along an imaginary plane perpendicular to the axis x. FIG. 9 is a partially enlarged cross-sectional view of a portion of the cross-sectional view of FIG. 8. FIG. 10 is a cross-sectional view taken along line 10-10 in FIG. 8. Note that, for simplification, the right crank arm 5A and the chain ring 7 are omitted from FIG. 10. Referring to FIGS. 9 and 10 together, the stator 8 has a magnetic body, i.e., a stator core 81, a coil 82, and an insulator 83.

[0031] The stator core 81 is formed from a laminate of magnetic materials such as silicon steel plates. The stator core 81 functions as a yoke for the stator 8. The stator core 81 has a cylindrical portion (hereinafter referred to as the "cylindrical portion") 84 centered on the axis x, and a plurality of (e.g., 18) teeth 85 extending radially outward from the outer circumferential surface of the cylindrical portion 84. The stator core 81 is attached to the outer circumferential surface 331d of the outer sleeve 331 at the inner circumferential surface 84a of the cylindrical portion 84. A coil 82 is wound around each tooth 85 with its winding axis in the radial direction. An insulator 83 is disposed between the tooth 85 and the coil 82. The insulator 83 insulates the stator core 81 from the coil 82.

[0032] The rotor 9, which faces the stator 8 in the radial direction, has a magnet 91, a yoke 92, and a housing 93. The magnet 91 is a cylindrical permanent magnet centered on the axis x. The magnet 91 may be a single cylindrical permanent magnet, or multiple permanent magnets may be connected circumferentially to form a cylindrical shape. The cylindrical inner surface of the magnet 91 faces the outer peripheral surfaces of the teeth 85 of the stator core 81 across a predetermined magnetic gap. The cylindrical outer surface of the magnet 91 is fixed, for example, by adhesive or the like, to the inner peripheral surface of a substantially cylindrical yoke 92 centered on the axis x. The yoke 92 is formed, for example, from a magnetic material.

[0033] The housing 93 includes a first housing 931 disposed on the right crank arm 5A side and a second housing 932 disposed on the left crank arm 6 side. Both the first housing 931 and the second housing 932 are formed in an annular shape. The first housing 931 includes, for example, a flat plate portion 931a (hereinafter referred to as the "flat plate portion") extending annularly along an imaginary plane perpendicular to the axis x, and a side wall portion 931b (hereinafter referred to as the "side wall portion") extending annularly from the outer peripheral end of the flat plate portion 931a toward the second housing 932 along the axis x. The first housing 931 is fixed to the inner surface 51a of the main body 51 by the flat plate portion 931a. Fastening parts (not shown), such as bolts, are used for the fixation.

[0034] The second housing 932 has, for example, a flat plate portion (hereinafter referred to as the "flat plate portion") 932a extending annularly along an imaginary plane perpendicular to the axis x, and a side wall portion (hereinafter referred to as the "side wall portion") 932b extending annularly from the outer peripheral end of the flat plate portion 932a toward the first housing 931 along the axis x. The yoke 92 has its outer peripheral surface fixed to the inner peripheral surface of the side wall portion 931b of the first housing 931 and the inner peripheral surface of the side wall portion 932b of the second housing 932, for example, by adhesive or the like. In this way, the first housing 931 and the second housing 932 as a whole define, for example, an annular accommodation space for accommodating the above-mentioned stator 8.

[0035] At least the right crank arm 5A, rotor 9, bracket 33, bearing 32, stator 8, and crankshaft 4 described above constitute a power generator 10A according to a second embodiment of the present invention. The power generator 10A includes wiring (not shown) that bundles together multiple wires drawn from the coil 82. This wiring is electrically connected to, for example, electronic devices mounted on the bicycle. Examples of electronic devices include lights, electric shifters, electric brakes, a cycle computer, and various sensors. The various sensors include sensors capable of communicating with the cycle computer using, for example, a predetermined wireless communication standard. The wiring drawn from the coil 82 may also be connected to an electrical component such as a capacitor with a power storage function.

[0036] When such a crankset 1A is installed on a bicycle, pedaling causes the right crank arm 5A 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 stator 8 and the rotor 9 to rotate relative to each other. As a result, magnetic interaction between the magnet 91 and the coil 82 generates electrical energy in the coil 82. The electrical energy generated in this manner is sent via wiring to electronic devices mounted on the bicycle. The electronic devices can be powered by this electrical energy. The electrical energy generated by the power generation device 10A may be temporarily stored in a power storage device such as a capacitor.

[0037] In the crankset 1A described above, the power generator 10A is installed adjacent to the bottom bracket shell 2. Specifically, the stator 8 and rotor 9 are disposed outside the bottom bracket 3A, adjacent to the inner surface 51a of the right crank arm 5A. The stator 8 is fixed to the bottom bracket 3A, while the rotor 9 is fixed to the right crank arm 5A. In this way, the power generator 10A can generate electricity with a simple structure. Because the power generator 10A does not have a complex structure that could increase weight, the weight increase due to the installation of the power generator 10A can be suppressed. With this power generator 10A, there is no need to install a battery on the bicycle. This eliminates the hassle of battery charging. Furthermore, if a battery is already installed, the battery itself can be made lighter by reducing its capacity. Alternatively, the battery capacity can be kept the same, and the stored electricity in the battery can be dedicated to assisting the bicycle, thereby increasing the range of the assisted bicycle itself.

[0038] Next, the installation of the crankset 1A described above into the bottom bracket shell 2 will be described. First, the bottom bracket 3A is installed into the bottom bracket shell 2. Specifically, an outer peripheral sleeve 331 on the right crank arm 5A side, to which the bearing 32 and stator 8 are attached, and an outer peripheral sleeve 331 on the left crank arm 6 side, to which the bearing 32 and seal member 333 are attached, are fixed in the openings 21 and 22 of the bottom bracket shell 2, respectively. Note that an inner peripheral sleeve 332 is supported by one of the outer peripheral sleeves 331. Next, the crankshaft 4, to which the right crank arm 5A, to which the chainring 7, first housing 931, magnet 91, and yoke 92 are already attached, is installed at one end 41, and then inserted into the bottom bracket 3A. After the second housing 932 is attached to the yoke 92, the left crank arm 6 is attached to the other end 42 of the crankshaft 4. In this manner, the crankset 1A is installed into the bottom bracket shell 2.

[0039] Fig. 11 is a perspective view schematically showing the structure of a crankset 1B incorporating a power generator according to a third embodiment of the present invention. Fig. 12 is an exploded perspective view schematically showing the structure of a crankset 1B incorporating a power generator according to the third embodiment of the present invention. Referring to Figs. 11 and 12 together, this crankset 1B includes a bottom bracket 3A, a crankshaft 4, a right crank arm 5B, a left crank arm 6, and a chain ring 7. That is, compared to the crankset 1A described above, the structure of the right crank arm 5B is different from the structure of the right crank arm 5A. Other components similar to those of the crankset 1A of the second embodiment described above are designated by the same reference numerals, and redundant description will be omitted here.

[0040] Compared to the structure of the crank arm 5A according to the second embodiment, specifically, the housing 931 of the rotor 9 of the crankset 1 according to the second embodiment is formed integrally with the right crank arm 5B. As specifically shown in Figure 12, a recess 56 for accommodating the stator 8 and rotor 9 is formed in the body 51 of the right crank arm 5B. In this example, the recess 56 defines a flat, cylindrical accommodation space centered on the axis x. A magnet 91 and a yoke 92 that constitute the rotor 9 are fixed to the inner circumferential surface of the side wall 57 of the body 51 that forms the recess 56.

[0041] Figure 13 is a cross-sectional view taken along line 13-13 in Figure 11. Figure 14 is a cross-sectional view taken along line 14-14 in Figure 13. Referring to Figures 11 to 13 together, as in the second embodiment, the stator 8 is fixed to the outer peripheral surface 331d of the outer peripheral sleeve 331 of the bottom bracket 3A. The stator 8 has a stator core 81, a coil 82, and an insulator 83. A magnet 91 fixed to the side wall 57 of the recess 56 in the main body 51 faces the stator 8 in the radial direction, with a predetermined magnetic gap between them.

[0042] The rotor 9 has a housing 94 that covers the recess 56. The housing 94 has a flat, annular plate portion (hereinafter referred to as the "flat plate portion") 941 that is flat around the axis x, and a protrusion 942 that protrudes radially from the outer periphery of the flat plate portion 941. A hole, i.e., a through-hole 943 that extends parallel to the axis x is formed in the protrusion 942. A fastening part, i.e., a bolt 95, is threaded through this through-hole 943 and into a hole, i.e., a screw hole 58, formed in the protrusion 53 of the main body 51, thereby fixing the housing 94 to the right crank arm 5B. The flat plate portion 941 of the housing 94 covers the recess 56 around the bottom bracket 3A.

[0043] At least the above-described right crank arm 5B, rotor 9, bracket 33, bearing 32, stator 8, and crankshaft 4 constitute a power generator 10B according to a third embodiment of the present invention. In this crankset 1B, the power generator 10B is assembled adjacent to the bottom bracket shell 2, similar to the crankset 1A. Specifically, the stator 8 and rotor 9 are disposed outside the bottom bracket 3A and within a recess 56 in the right crank arm 5B. The stator 8 is fixed to the bottom bracket 3A, while the rotor 9 is fixed to the right crank arm 5B. In this way, the power generator 10B can generate electricity with a simple structure.

[0044] Next, the installation of the crankset 1B described above into the bottom bracket shell 2 will be described. First, the bottom bracket 3A is installed into the bottom bracket shell 2. Specifically, the outer peripheral sleeve 331 on the right crank arm 5B side, to which the bearing 32 and stator 8 are attached, and the outer peripheral sleeve 331 on the left crank arm 6 side, to which the bearing 32 is attached, are fixed in the openings 21 and 22 of the bottom bracket shell 2, respectively. Note that an inner peripheral sleeve 332 is supported by one of the outer peripheral sleeves 331. Next, the crankshaft 4, to which the right crank arm 5B, to which the chainring 7, magnet 91, and yoke 92 are already attached, is installed at one end 41, by insertion or the like, into the bottom bracket 3A. After the housing 94 is installed on the right crank arm 5B, the left crank arm 6 is installed at the other end 42 of the crankshaft 4. In this manner, the crankset 1B is installed into the bottom bracket shell 2.

[0045] 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 will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0046] 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 arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified 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.

[0047] 1, 1A, 1B Crankset, 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 Fitting portion (fitting portion), 331b Protruding portion (flange portion), 331c Groove, 331d Outer peripheral surface, 331e Inner peripheral surface, 332 Inner peripheral sleeve (inner peripheral sleeve), 332a Recess, 333 Sealing 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, 51a one side surface (inner surface), 52 hole (mounting hole), 53 protruding portion (protruding portion), 54 arm main body, 55 hole (screw hole), 56 recess, 57 side wall, 58 hole (screw hole), 6 left crank arm, 61 arm main body, 62 hole (mounting hole), 7 chain ring, 71 hole (through hole), 72 bolt, 8 stator, 81 magnetic body (stator core), 82 coil, 83 insulator, 84 cylindrical portion (cylindrical portion), 84a inner peripheral surface, 85 teeth, 9 rotor, 91 magnet, 92 yoke, 93 housing, 931 first housing, 931a flat portion (flat portion), 931b side wall portion (side wall portion), 932 second housing, 932a flat portion (flat portion), 932b Side wall portion (side wall portion), 94 housing, 941 flat plate portion (flat plate portion), 942 protrusion, 943 hole (through hole), 95 fastening part (bolt), 10, 10A, 10B power generation device, x axis

Claims

1. A generator comprising: 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, wherein a magnet is fixed to a side 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 the direction of the rotation axis.

4. The power generating device according to any one of claims 1 to 3, wherein the magnet is fixed to the outer circumferential side surface of the crankshaft.

5. The power generating device according to any one of claims 1 to 3, wherein the magnet is fixed in a recess in the outer circumferential side surface of the crankshaft.

6. A power generating device according to any one of claims 1 to 5, comprising a plurality of the bearings, the magnet and the stator being positioned between the plurality of bearings in the direction of the rotation axis.

7. A power generating device comprising: a crank arm; a rotor fixed to the crank arm; a bracket; a stator fixed to the bracket; a bearing; and a crankshaft supported by the bracket via the bearing.

8. The power generating device of claim 7, wherein the rotor comprises a magnet.

9. The power generating device according to claim 7 or 8, wherein the stator comprises a magnetic body and a coil wound around the magnetic body.

10. The power generating device according to any one of claims 7 to 9, wherein the rotor is fixed to a surface of the crank arm facing the crankshaft.

11. The power generating device according to any one of claims 7 to 10, wherein the stator is fixed to a surface of the bracket on the crank arm side.

12. The power generating device according to any one of claims 7 to 11, wherein the bearing is fixed to a surface of the bracket on the crankshaft side.

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