The electric motor rotates in the form of an outer rotor.

Abstract

DEPCT63 The rotor linkage (20) consists of the rotor hub (21) which is mounted on and secured to Crankshaft (102), the disc-shaped lower part (22) is fitted at the end of the rotor hub (21) on top. It is opposite to the engine (100) and is constructed in a manner congruent with the axis of rotation (C) of the shaft. Crankshaft (102) and side sections (23) that protrude and bend on the side of the engine (100) from the edge line. The outer perimeter of the base section (22) covers the outer perimeter surface of the stator (2) and has a perimeter surface. The inner part containing the magnet (34) is arranged, with a protrusion (31) extending onto the side opposite the engine. (100) will be provided on the outer perimeter and the cooling fan (4) will also be provided on. One skin (22a) of the lower part (22) on the side opposite the engine (100). -----------------------------------------------------------

Description

Outer rotor type rotating electric machine

[0001] The present invention relates to an outer rotor type rotating electric machine. This application claims priority to International Application PCT / JP2017 / 039711, filed November 2, 2017, the contents of which are incorporated herein by reference.

[0002] An outer rotor type rotating electric machine, for example, is used in vehicles such as motorcycles and has two functions: an engine start function and a power generation function that converts a portion of the engine's rotational motion into electrical energy. This type of rotating electric machine includes a stator wound with a coil and a flywheel unit (rotor) that includes a rotor yoke formed in a cylindrical shape with a bottom and surrounding the stator, with multiple magnets arranged on its inner circumferential surface. This type of rotating electric machine is disposed near the engine, and the flywheel unit is attached to the engine's crankshaft. The flywheel unit rotates integrally with the crankshaft. There is a strong demand for miniaturization and high performance in such rotating electric machines. To achieve high performance, a cooling fan for cooling the engine and rotating electric machine may be provided at the bottom of the flywheel unit.

[0003] JP 2016-111909 A

[0004] However, when a cooling fan is provided in a flywheel unit as in the conventional technology described above, in order for the cooling fan to function efficiently, it needs to be located on the opposite side of the rotating electrical machine from the engine. For example, if the cooling fan is located between the engine and the rotating electrical machine, it will be difficult for the cooling fan to take in a large amount of outside air, reducing the efficiency of the cooling fan. Therefore, by locating the cooling fan on the opposite side of the rotating electrical machine from the engine, it will be possible for the cooling fan to take in more outside air, thereby improving the efficiency of the cooling fan.

[0005] However, if the cooling fan is placed on the opposite side of the rotating electrical machine from the engine, the flywheel unit will be placed at a position away from the engine, which could make the crankshaft more likely to whirl.

[0006] Furthermore, in order to improve engine startability and the efficiency of the rotating electrical machine, it is possible to increase the weight of the rotor yoke in order to increase the inertia force of the flywheel unit. However, simply increasing the weight of the rotor yoke would result in an increase in the size of the rotor yoke, which could result in an increase in the size of the flywheel unit and the entire rotating electrical machine.

[0007] The present invention provides an outer rotor type rotating electrical machine that can be effectively downsized and has high performance.

[0008] According to a first aspect of the present invention, an outer rotor type rotating electric machine comprises a stator fixed to an engine, and a rotor yoke attached to the engine crankshaft and covering the stator from the side opposite the engine, the rotor yoke comprising a rotor boss fitted and fixed to the crankshaft, a disk-shaped bottom portion provided at the end of the rotor boss opposite the engine and formed coaxially with the rotation axis of the crankshaft, and a side portion bent and extended from the outer peripheral edge of the bottom toward the engine, covering the outer peripheral surface of the stator and having a magnet on its inner peripheral surface, and the surface of the bottom opposite the engine is provided with a protrusion on the outer peripheral portion that protrudes toward the side opposite the engine, and is provided with a cooling fan.

[0009] In this way, by forming a convex portion on the outer peripheral surface of the bottom of the rotor yoke that protrudes toward the opposite side from the engine, the weight of the outer peripheral portion of the rotor yoke can be effectively increased compared to the radial center of the rotor yoke. As a result, the inertia force of the rotor yoke can be efficiently increased while suppressing an increase in the size of the rotor yoke. Furthermore, there is no need to extend the crankshaft, and whirling of the crankshaft can be suppressed. Furthermore, since a cooling fan is provided on the surface of the bottom of the rotor yoke opposite the engine, there is no need to place a cooling fan between the engine and the outer rotor type rotating electric machine, and the cooling fan can be placed on the opposite side of the engine of the outer rotor type rotating electric machine. Therefore, the outer rotor type rotating electric machine can be made smaller and have higher performance.

[0010] According to a second aspect of the present invention, in the outer rotor type rotating electrical machine according to the first aspect of the present invention, the convex portion is formed over the entire outer periphery of the bottom portion.

[0011] With this configuration, the weight of the outer peripheral portion of the rotor yoke can be more reliably increased compared to the radial center of the rotor yoke, thereby reliably increasing the inertial force of the rotor yoke.

[0012] According to a third aspect of the present invention, the outer rotor type rotating electric machine according to the first or second aspect of the present invention has a plurality of communication holes formed in the convex portion at positions corresponding to the midpoints between adjacent magnets.

[0013] With this configuration, for example, a magnet positioning jig can be inserted into the communication hole from the outside of the bottom of the rotor yoke, making it easier to use this positioning jig and therefore easier to assemble the magnet into the rotor yoke.

[0014] According to a fourth aspect of the present invention, in an outer rotor type rotating electric machine according to any one of the first to third aspects of the present invention, a mounting seat having a mounting hole for connecting the bottom part to the rotor boss is provided in the radial center of the bottom part, and the mounting seat is positioned shifted toward the engine from the bottom part.

[0015] The rotor yoke is positioned to cover the stator from the side opposite the engine. Therefore, the mounting seat connecting the rotor boss, which is fitted and fixed to the crankshaft, to the bottom can be shifted toward the engine, allowing the crankshaft protruding from the engine to be shortened. This effectively suppresses whirling of the crankshaft, further reducing the size and improving the performance of the outer rotor rotating electric machine.

[0016] According to a fifth aspect of the present invention, in the outer rotor type rotating electric machine according to the third aspect of the present invention, a magnet cover is provided which is fixed to the inner surface of the bottom of the rotor yoke and which covers the magnet from the inner surface side to hold the magnet, and a hole is formed in the magnet cover which connects the radial inside of the rotor yoke with the communication hole of the rotor yoke.

[0017] With this configuration, the magnet cover can reliably secure the magnet to the rotor yoke. Furthermore, even when the magnet cover is provided, the holes in the magnet cover and the communication holes in the rotor yoke can be used to reliably drain water droplets and other contaminants from inside the rotor yoke to the outside of the rotor yoke. In other words, the communication holes function as drainage holes. This reliably prevents malfunctions, providing a highly reliable outer rotor rotating electric machine.

[0018] According to a sixth aspect of the present invention, in the outer rotor type rotating electric machine relating to the fifth aspect of the present invention, the magnet cover comprises a cover main body covering the inner surface of the magnet, an inner flange portion extending radially inward from the bottom side end of the rotor yoke in the cover main body, and an outer flange portion extending radially outward from the opening side end of the rotor yoke in the cover main body, wherein the inner flange portion is fixed to the inner surface of the bottom and the hole is formed in the inner flange portion.

[0019] With this configuration, the magnet cover can protect the magnet while reliably discharging water droplets and the like from within the rotor yoke to the outside of the rotor yoke.

[0020] According to a seventh aspect of the present invention, in the outer rotor type rotating electric machine according to the fifth or sixth aspect of the present invention, the holes are formed at positions that do not overlap with the magnets in the radial direction.

[0021] This configuration can prevent the magnet from becoming wet, compared to when the hole is formed at a position that overlaps the magnet in the radial direction.

[0022] According to an eighth aspect of the present invention, in the outer rotor type rotating electric machine relating to the third aspect of the present invention, a magnet cover is provided which is fixed to the inner surface of the bottom of the rotor yoke and covers the magnet from the inner surface side to hold the magnet, and a slit is formed in the magnet cover to connect the radial inner side of the rotor yoke with the communication hole of the rotor yoke.

[0023] With this configuration, the magnet cover can reliably secure the magnet to the rotor yoke. Furthermore, even when the magnet cover is provided, water droplets and the like inside the rotor yoke can be reliably drained to the outside of the rotor yoke by utilizing the slits formed in the magnet cover and the communication holes formed in the rotor yoke. In other words, the communication holes function as drainage holes. Furthermore, water droplets and the like can be reliably prevented from accumulating in the gap between the rotor yoke and the inner flange portion of the magnet cover. This makes it possible to provide an outer rotor rotating electric machine that can reliably prevent malfunctions and has high reliability.

[0024] According to a ninth aspect of the present invention, in the outer rotor type rotating electric machine relating to the eighth aspect of the present invention, the magnet cover comprises a cover main body covering the inner surface of the magnet, an inner flange portion extending radially inward from the bottom side end of the rotor yoke in the cover main body, and an outer flange portion extending radially outward from the opening side end of the rotor yoke in the cover main body, wherein the inner flange portion is fixed to the inner surface of the bottom and the slit is formed in the inner flange portion.

[0025] With this configuration, the magnet cover can protect the magnet while reliably discharging water droplets and the like from within the rotor yoke to the outside of the rotor yoke.

[0026] According to a tenth aspect of the present invention, in the outer rotor type rotating electric machine according to the eighth or ninth aspect of the present invention, the slits are formed at positions that do not overlap with the magnets in the radial direction.

[0027] By configuring in this manner, the magnet can be prevented from becoming wet, compared to when a slit is formed at a position that overlaps with the magnet in the radial direction.

[0028] According to an eleventh aspect of the present invention, a motorcycle comprises an outer rotor type rotating electric machine described in any one of the above items, a body to which the outer rotor type rotating electric machine is mounted, and a side stand provided on the outside of the body in the vehicle width direction, and the outer rotor type rotating electric machine and the side stand are arranged on the same side of the body in the vehicle width direction.

[0029] When an outer rotor type rotating electric machine is mounted on the outer side of the vehicle body in the vehicle width direction of a motorcycle, water droplets and the like may accumulate on the rotor yoke depending on the tilt direction of the vehicle body. In particular, when the vehicle body is parked using the side stand, the body is tilted toward the side stand. Therefore, if an outer rotor type rotating electric machine is mounted on the same side of the vehicle body as the side stand, the side of the rotor yoke slopes downward from the opening side to the bottom side. This may result in water droplets and the like accumulating on the rotor yoke. However, a communication hole is formed in the bottom of the rotor yoke, and a hole communicating with the communication hole is formed in the magnet cover. As a result, water droplets and the like inside the rotor yoke can be reliably discharged to the outside of the rotor yoke. This reliably prevents malfunctions of the motorcycle and improves its reliability.

[0030] According to the present invention, by forming a convex portion on the outer peripheral surface of the bottom of the rotor yoke that protrudes toward the opposite side from the engine, the weight of the outer peripheral portion of the rotor yoke can be effectively increased compared to the radial center of the rotor yoke. As a result, the inertia force of the rotor yoke can be efficiently increased while suppressing an increase in the size of the rotor yoke. Furthermore, there is no need to extend the crankshaft, and whirling of the crankshaft can be suppressed. Furthermore, since a cooling fan is provided on the surface of the bottom of the rotor yoke opposite the engine, there is no need to place a cooling fan between the engine and the outer rotor type rotating electric machine, and the cooling fan can be placed on the opposite side of the engine of the outer rotor type rotating electric machine. Therefore, the outer rotor type rotating electric machine can be made smaller and have higher performance.

[0031] Fig. 1 is a cross-sectional view of an outer rotor type rotating electric machine according to a first embodiment of the present invention. Fig. 2 is an exploded perspective view of an outer rotor type rotating electric machine according to the first embodiment of the present invention. Fig. 3 is an exploded perspective view of a rotor according to the first embodiment of the present invention. Fig. 4 is a plan view of a side portion of a rotor yoke according to the first embodiment of the present invention, viewed from the inner peripheral surface side. Fig. 5 is a plan view of a rotating electric machine according to a second embodiment of the present invention, attached to a body of a motorcycle, viewed from the rear in the direction of travel of the body. Fig. 6 is a perspective view of a magnet cover according to the second embodiment of the present invention.

[0032] Next, an embodiment of the present invention will be described with reference to the drawings.

[0033] (First embodiment) (Outer rotor type rotating electric machine) Fig. 1 is a cross-sectional view of an outer rotor type rotating electric machine 1. Fig. 2 is an exploded perspective view of the outer rotor type rotating electric machine 1. As shown in Figs. 1 and 2 , the outer rotor type rotating electric machine (hereinafter simply referred to as rotating electric machine) 1 includes a stator 2 fixed to a crankcase 101 of an engine 100 of, for example, a motorcycle, a flywheel unit 3 attached to a crankshaft 102 of the engine 100, and a cooling fan 4 provided in the flywheel unit 3. In the following description, a direction along a rotation axis C of the flywheel unit 3 (crankshaft 102) will be simply referred to as the axial direction, a radial direction of the flywheel unit 3 perpendicular to the axial direction will be simply referred to as the radial direction, and a rotation direction of the flywheel unit 3 perpendicular to the axial and radial directions will be simply referred to as the circumferential direction.

[0034] (Stator) The stator 2 has a substantially annular stator core 5. This stator core 5 is fastened to the crankcase 101 of the engine 100 with bolts (not shown). The stator core 5 is formed, for example, by stacking magnetic material plates in the axial direction. However, this is not limiting, and the stator core 5 may be formed, for example, by pressure molding soft magnetic powder. A through hole 5a is formed in the radial center of the stator core 5, penetrating it in the axial direction. A crankshaft 102 and a rotor boss 21 (described later) are inserted through this through hole 5a. The tip of the crankshaft 102 protrudes from the stator core 5 on the side opposite the crankcase 101 via the through hole 5a and the rotor boss 21.

[0035] The stator core 5 has three bolt insertion holes 5b formed at equal intervals around the circumference, through which bolts (not shown) can be inserted to fasten the stator core 5 to the crankcase 101. The outer peripheral surface of the stator core 5 is further provided with a plurality of teeth 6 that protrude radially outward in the radial direction. A coil 8 is wound around each tooth 6 from above an insulator 7 attached to the tooth 6. An end of each coil 8 is pulled out toward the crankcase 101 (the left side in FIG. 1 , the upper side in FIG. 2 ).

[0036] Terminal portions of these coils 8 are bundled and held by harness clips 9 provided on one surface 5c of the stator core 5 facing the crankcase 101. A female thread 5d is formed on one surface 5c of the stator core 5 for fastening and fixing the harness clip 9 with a bolt 10. The terminal portions of the coils 8 are connected to a harness and electrically connected to a higher-level controller (neither of which is shown) or the like.

[0037] A position detection sensor 11 is provided on one surface 5c of the stator core 5. The position detection sensor 11 detects the rotational position of the flywheel unit 3. The position detection sensor 11 has a sensor board 15, on which a magnetic detection element (not shown) is mounted, housed in a sensor case 12. The magnetic detection element detects the magnetic flux of a magnet 34 (described below) of the flywheel unit 3. The magnetic flux changes as the flywheel unit 3 rotates, so the position detection sensor 11 detects the rotational position of the flywheel unit 3 by detecting this change in magnetic flux. The sensor case 12 is provided with a female thread 12a for fastening the sensor case 12 to the stator core 5 with a bolt 14.

[0038] Meanwhile, the stator core 5 is formed with bolt insertion holes 13 through which bolts 14 can be inserted from the other surface 5e opposite to the one surface 5c. The bolts 14 inserted into the bolt insertion holes 13 are threaded into the female threaded portions 12a of the sensor case 12, thereby fastening and fixing the sensor case 12 to the stator core 5. The bolt insertion holes 13 are also formed with counterbore portions 13a so that the heads of the bolts 14 inserted into the bolt insertion holes 13 do not protrude from the other surface 5e of the stator core 5.

[0039] (Flywheel Unit) Figure 3 is an exploded perspective view of the flywheel unit 3. As shown in Figures 1 to 3, the flywheel unit 3 includes a rotor yoke 20 having an opening 20a on the crankcase 101 side so as to cover the stator 2 from the side opposite the crankcase 101 (the side of the other surface 5e of the stator core 5). That is, the rotor yoke 20 includes a rotor boss 21 fitted and fixed to the tip end of the crankshaft 102, a substantially disc-shaped bottom portion 22 provided at the end of the rotor boss 21 opposite the crankcase 101, and a substantially cylindrical side portion 23 that bends and extends from the outer periphery of the bottom portion 22 toward the crankcase 101 and covers the outer periphery of the stator core 5. The peripheral edge of the side portion 23 opposite the bottom portion 22 forms the opening 20a of the rotor yoke 20.

[0040] The rotor boss 21 has a generally cylindrical boss body 24 that is fitted and fixed onto the tip end of the crankshaft 102. The boss body 24 is disposed within the through hole 5a of the stator core 5 with a predetermined gap between it and the inner peripheral surface of the through hole 5a. A generally cylindrical boss-side connecting portion 25 that is expanded in diameter by a step portion 24a is integrally molded with the boss body 24 at the end opposite the crankshaft 102. The boss-side connecting portion 25 connects the rotor boss 21 and the bottom portion 22. A small flange portion 25a that projects radially outward is formed on the outer peripheral surface of the boss-side connecting portion 25 at a position corresponding to the step portion 24a.

[0041] Furthermore, a large flange portion 25b, which has a larger diameter than the small flange portion 25a, is integrally formed on the outer peripheral surface of the boss-side connecting portion 25 at the end opposite the boss body 24. A mounting seat 27 (described later) of the bottom portion 22 is disposed between the small flange portion 25a and the large flange portion 25b. The mounting seat 27 of the bottom portion 22 is disposed so as to be sandwiched between the small flange portion 25a and the large flange portion 25b.

[0042] Additionally, boss-side serrations 26 are formed on the outer peripheral surface of the boss-side connecting portion 25 between the small flange portion 25a and the large flange portion 25b. These boss-side serrations 26 cooperate with bottom-side serrations 29 formed on the bottom portion 22 to prevent the bottom portion 22 from rotating relative to the rotor boss 21.

[0043] A mounting seat 27 formed in a substantially annular plate shape is integrally formed in the radial center of the bottom portion 22. The mounting seat 27 is formed by pressing the bottom portion 22 so that it is slightly offset from the bottom portion 22 toward the crankcase 101. The amount of offset Δt between the bottom portion 22 and the mounting seat 27 can be set as desired.

[0044] The mounting seat 27 has a generally cylindrical bottom-side connecting portion 28 whose inner peripheral edge is bent and rises slightly toward the crankcase 101. The outer peripheral surface of the boss-side connecting portion 25 is press-fitted onto the inner peripheral surface of the bottom-side connecting portion 28. The distance between the small flange portion 25a and the large flange portion 25b of the rotor boss 21 is set to be equal to the axial height of the bottom-side connecting portion 28. As a result, the mounting seat 27 is fitted onto the rotor boss 21 and is sandwiched between the small flange portion 25a and the large flange portion 25b.

[0045] Additionally, bottom-side serrations 29 are formed on the inner peripheral surface of the bottom-side connecting portion 28. These bottom-side serrations 29, together with the boss-side serrations 26 formed on the rotor boss 21, connect the mounting seat 27 (bottom portion 22) to the rotor boss 21 so as not to rotate relative to the rotor boss 21. It is desirable to set the outer radius of curvature R1 of the bent portion of the bottom-side connecting portion 28 as small as possible. By setting the radius of curvature R1 in this manner, the area of ​​the inner peripheral surface of the bottom-side connecting portion 28 can be maximized. This ensures that the contact area between the inner peripheral surface of the bottom-side connecting portion 28 and the outer peripheral surface of the rotor boss 21 is maximized. This ensures that the rotor boss 21 and the mounting seat 27 are securely fixed to each other.

[0046] The bottom portion 22 is formed with a plurality of (e.g., three in the first embodiment) through holes 32 at equal intervals in the circumferential direction around the mounting seat 27. The through holes 32 serve to reduce the weight of the rotor yoke 20. By designing the cooling fan 4 so that the through holes 32 are not blocked, air can be drawn into the stator 2 through the through holes 32, thereby enhancing the cooling effect of the stator 2. Furthermore, the bottom portion 22 is formed with a plurality of mounting bosses 40 at equal intervals in the circumferential direction, slightly closer to the outer periphery than the through holes 32. The mounting bosses 40 are formed by pressing the bottom portion 22 so as to protrude toward the crankcase 101. The mounting bosses 40 are used to secure a magnet cover 35, which will be described later.

[0047] Furthermore, a convex portion 31 that protrudes toward the opposite side from the crankcase 101 is formed around the entire circumference of the outer periphery of the bottom portion 22. That is, the convex portion 31 is formed in a substantially annular shape when viewed in the axial direction. The convex portion 31 is formed by press-working the bottom portion 22, thereby first bending the outer periphery of the bottom portion 22 toward the opposite side from the crankcase 101 and then folding it back toward the crankcase 101. That is, the convex portion 31 has a substantially C-shaped cross section with the crankcase 101 side open, and is composed of an inner wall 31a that rises from the bottom portion 22 along the axial direction and toward the opposite side from the crankcase 101, a flat lateral wall 31b that bends and extends radially outward from the tip of the inner wall 31a, the lateral wall 31b, and an outer wall 31c that bends and extends axially from the radially outer end of the lateral wall 31b toward the crankcase 101 side.

[0048] A plurality of jig holes (communicating holes) 33 are formed in the side wall 31b at equal intervals in the circumferential direction. The jig holes 33 are formed in an oval shape that is elongated in the circumferential direction so as to form an arc shape when viewed in the axial direction. The jig holes 33 are used to position the magnets 34 provided on the inner circumferential surface of the side portion 23 (details will be described later). Here, since the convex portion 31 is formed by bending the bottom portion 22 by press working, it is desirable to set the outer radius of curvature R2 of the bent portion between the bottom portion 22 and the inner wall 31a as large as possible. Setting the radius of curvature R2 in this manner allows the thickness of the bottom portion 22 and the inner wall 31a to be set as thick as possible.

[0049] By forming a protrusion 31 on the outer periphery of the bottom 22, a recess 41 is formed radially inward of the protrusion 31. This recess 41 functions as a cooling fan storage recess 42 that stores the cooling fan 4. In other words, the cooling fan 4 is fastened and fixed to the bottom 22 of the rotor yoke 20 while stored in the cooling fan storage recess 42. A plurality of (for example, three in the first embodiment) female threads 43 for fastening and fixing the cooling fan 4 are formed in the bottom 22 at equal intervals in the circumferential direction.

[0050] The side portion 23 of the rotor yoke 20 extends axially from the tip of the outer wall 31c of the protrusion 31. A plurality of magnets 34 are provided on the inner peripheral surface of the side portion 23 at a position facing the stator core 5 in the radial direction. The magnets 34 are arranged at equal intervals so that their magnetic poles are in order. The number of gaps between the magnets 34 matches the number of jig holes 33 formed in the rotor yoke 20. The gaps between the magnets 34 are located at the circumferential centers of the jig holes 33.

[0051] Each magnet 34 is held by a magnet cover 35 fixed to the rotor yoke 20. The magnet cover 35 is composed of a cover main body 36 that covers the inner peripheral surface of each magnet 34, an inner flange portion 37 that protrudes radially inward from the end of the cover main body 36 on the side of the bottom 22 of the rotor yoke 20, and an outer flange portion 38 that protrudes radially outward from the end of the cover main body 36 on the side of the opening 20a of the rotor yoke 20.

[0052] The cover body 36 is formed so that its outer peripheral surface abuts against the inner peripheral surface of the magnets 34 provided on the side portion 23 of the rotor yoke 20. Furthermore, the cover body 36 is formed with ridges 36a that protrude axially and radially inward at positions corresponding to the gaps between the magnets 34. These ridges 36a hold the magnets 34 at a predetermined distance. In other words, no magnets 34 are present on the ridges 46a, and the circumferential positioning of each magnet 34 is determined by the ridges 36a.

[0053] The inner flange portion 37 is composed of an inclined portion 51 that extends radially inward from the end of the cover body 36 near the bottom 22 of the rotor yoke 20 and obliquely toward the bottom 22, and an abutting portion 52 that bends and extends radially inward from the inclined portion 51 and abuts against the bottom 22 of the rotor yoke 20. The abutting portion 52 of the inner flange portion 37 is formed with a fitting hole 39 that can fit into a mounting boss 40 formed on the bottom 22 of the rotor yoke 20, at a position that corresponds to the mounting boss 40. After the mounting boss 40 is attached to the fitting hole 39, the mounting boss 40 is crimped to secure the magnet cover 35 to the rotor yoke 20.

[0054] The outer flange portion 38 is formed to cover the end of the magnet 34 on the side of the opening 20a of the rotor yoke 20. This prevents the magnet 34 from coming off the rotor yoke 20.

[0055] Here, it is desirable to set the inner radius of curvature R3 of the bend between the bottom portion 22 and the inner wall 31a as small as possible. By reducing the radius of curvature R3, the mounting boss 40 formed on the bottom portion 22 can be positioned as close as possible to the protrusion 31 of the rotor yoke 20 (positioned radially outward). By positioning the mounting boss 40 close to this protrusion 31, the size of the inner flange portion 37 can be minimized as much as possible. This makes it possible to reduce the weight and cost of the entire flywheel unit 3.

[0056] (Rotor Assembly Method) Next, a method for assembling the flywheel unit 3 will be described. Figure 4 is an explanatory diagram showing an intermediate step in the method for assembling the flywheel unit 3, and is a plan view of the side portion 23 of the rotor yoke 20 as viewed from the inner peripheral surface side. As shown in the figure, first, the positioning protrusions Zt of the jig Z are inserted into each jig hole 33 formed in the protrusion 31 of the rotor yoke 20 from the side of the surface 22a opposite to the opening 20a of the rotor yoke 20 (see Figure 3, the lower side in Figure 4).

[0057] The positioning protrusions Zt have an axial positioning portion 103 whose cross section is formed to correspond to the jig hole 33 of the rotor yoke 20, and a circumferential positioning portion 104 that protrudes from the axial positioning portion 103 toward the opening 20a of the rotor yoke 20 (upward in FIG. 4 ). The rotor yoke 20 is circumferentially positioned relative to the positioning protrusions Zt by inserting the positioning protrusions Zt into the jig hole 33 of the rotor yoke 20. Furthermore, the rotor yoke 20 is axially positioned relative to the jig Z by placing the side walls 31b of the protrusions 31 on a table or workbench (not shown) of the jig Z. For this reason, it is desirable to maximize the flatness of the side walls 31b. Increasing the flatness of the side walls 31b minimizes tilting of the rotor yoke 20 relative to the jig Z.

[0058] Next, with the jig Z attached to the rotor yoke 20, the magnet 34 is set between circumferentially adjacent positioning protrusions Zt. At this time, one axial end of the magnet 34 is abutted against the axial positioning portion 103 of the positioning protrusion Zt. Furthermore, the circumferential positioning portion 104 of the positioning protrusion Zt is interposed between circumferentially adjacent magnets 34. This positions the magnet 34 relative to the positioning jig Z. Then, since the rotor yoke 20 is positioned relative to the positioning jig Z, the magnet 34 is positioned relative to the rotor yoke 20. Thereafter, the magnet cover 35 is attached to the rotor yoke 20. This completes the assembly of the flywheel unit 3.

[0059] (Operation of Rotating Electric Machine) Next, the operation of the rotating electric machine 1 will be described. First, the power generation function of converting part of the rotational motion of the engine into electrical energy will be described. When the crankshaft 102 rotates, the flywheel unit 3 rotates integrally with the crankshaft 102. This changes the magnetic flux of the magnet 34 of the flywheel unit 3, which passes through the teeth 6 of the stator 2. This change in magnetic flux becomes an electromotive force, which generates a current in the coil 8 of the stator 2. The current generated in the coil 8 is used for storing electricity in a battery (not shown) or for supplying power to an attached electrical device (not shown).

[0060] Here, the rotor yoke 20 of the flywheel unit 3 has a protrusion 31 formed on its outer periphery. This effectively increases the weight of the outer periphery of the rotor yoke 20 compared to the radial center of the rotor yoke 20. As a result, the inertial force of the rotor yoke 20 can be efficiently increased, and this inertial force can be used to rotate the rotor yoke 20 by inertia. This allows current to be generated in the coil 8 efficiently.

[0061] Next, the engine starting function will be described. When the rotating electric machine 1 starts the engine 100, current stored in the battery is selectively supplied to the coils 8. Which coils 8 to supply current to is controlled based on the detection result of the rotational position of the flywheel unit 3 by the position detection sensor 11. When current is supplied to the coils 8, magnetic flux is formed in the predetermined teeth 6, and magnetic attraction and repulsion are generated between this magnetic flux and the magnets 34 of the flywheel unit 3. As a result, the flywheel unit 3 rotates, which in turn rotates the crankshaft 102. This starts the engine 100. Here, because the rotor yoke 20 has the protrusions 31, a large inertial force can be obtained when the rotor yoke 20 begins to rotate. This inertial force can be used to efficiently rotate the crankshaft 102.

[0062] As described above, in the first embodiment, the outer periphery of the bottom portion 22 constituting the rotor yoke 20 is formed with a convex portion 31 that protrudes toward the opposite side from the crankcase 101. This effectively increases the weight of the outer periphery of the rotor yoke 20 compared to the radial center of the rotor yoke 20. As a result, the inertial force of the rotor yoke 20 can be efficiently increased. Furthermore, there is no need to increase the weight of the entire rotor yoke 20 in order to increase the inertial force of the rotor yoke 20. This prevents the rotor yoke 20 from becoming too large. Therefore, there is no need to extend the crankshaft 102 to attach the rotor yoke 20, and whirling of the crankshaft 102 can be suppressed.

[0063] Furthermore, the cooling fan 4 is provided on one surface 22a of the bottom 22 of the rotor yoke 20 opposite the crankcase 101. Therefore, the cooling fan 4 is not disposed between the crankcase 101 and the rotating electric machine 1. In other words, since the cooling fan 4 can be disposed on the side of the rotating electric machine 1 opposite the crankcase 101, the rotating electric machine 1 can be made smaller and have higher performance. Moreover, the recess 41 formed radially inward of the protrusion 31 of the rotor yoke 20 functions as a cooling fan storage recess 42 that stores the cooling fan 4. Therefore, even when the cooling fan 4 is provided on the rotor yoke 20, the overall axial length of the rotating electric machine 1 can be kept as small as possible.

[0064] Furthermore, the convex portion 31 of the rotor yoke 20 is formed around the entire outer periphery of the bottom portion 22. This allows the weight of the outer periphery of the rotor yoke 20 to be more effectively increased compared to the radial center of the rotor yoke 20. This reliably increases the inertial force of the rotor yoke 20. Furthermore, the lateral wall 31b of the convex portion 31 is formed with a plurality of jig holes 33 at equal intervals in the circumferential direction. The positioning protrusions Zt of a jig Z are inserted into these jig holes 33 from the side of the one surface 22a of the rotor yoke 20 to position the magnet 34 relative to the rotor yoke 20. In this way, the jig Z for the magnet 34 can be inserted from the outside (side of the one surface 22a) of the bottom portion 22 of the rotor yoke 20, facilitating the use of the jig Z. This facilitates the assembly of the magnet 34 to the rotor yoke 20.

[0065] Furthermore, a mounting seat 27 that connects to the rotor boss 21 is integrally formed in the radial center of the bottom portion 22 that constitutes the rotor yoke 20. The mounting seat 27 is formed by pressing the bottom portion 22 so that it is slightly offset from the bottom portion 22 toward the crankcase 101. Here, the rotor yoke 20 is provided so as to cover the stator 2 from the side of the stator 2 opposite the crankcase 101. Therefore, by offsetting the mounting seat 27 that connects to the rotor boss 21 that is externally fitted and fixed to the crankshaft 102 toward the crankcase 101, the length of the crankshaft 102 that protrudes from the crankcase 101 can be set as short as possible. This reliably suppresses whirling of the crankshaft 102, thereby enabling the rotating electric machine 1 to be more reliably made smaller and with higher performance.

[0066] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figures 5 and 6, with reference to Figures 1, 3, and 4. The same components as those in the first embodiment are designated by the same reference numerals, and a description thereof will be omitted. Figure 5 is a plan view of a rotating electric machine 201 according to the second embodiment attached to a body 202 of a motorcycle 200, as viewed from the rear of the body 202 in the direction of travel. Figure 5 also shows a state in which the body 202 is stopped using a side stand 203.

[0067] As shown in FIGS. 1 and 5 , in the second embodiment, a rotating electric machine 201 includes a stator 2 fixed to a crankcase 101 of an engine 100, a flywheel unit 3 attached to a crankshaft 102 of the engine 100, and a cooling fan 4 provided in the flywheel unit 3, similar to the first embodiment. Also, similar to the first embodiment, the flywheel unit 3 of the rotating electric machine 201 includes a rotor yoke 220 having an opening 220a on the crankcase 101 side so as to cover the stator 2 from the side opposite the crankcase 101 (the other surface 5e side of the stator core 5). Also, similar to the first embodiment, the magnet 34 provided on the rotor yoke 220 is held by a magnet cover 235. Other than this, the rotating electric machine 201 of the second embodiment has the same basic configuration as the rotating electric machine 1 of the first embodiment.

[0068] As shown in Fig. 5, the rotating electric machine 201 is attached to the outer side in the vehicle width direction of the vehicle body 202. The rotor yoke 220 of the rotating electric machine 201 is attached with the opening 220a facing the vehicle body 202 (engine 100, not shown in Fig. 5, see Fig. 1).

[0069] A side stand 203 is provided on one of both outer sides in the vehicle width direction of the vehicle body 202, on the same side as the side on which the rotating electric machine 201 is attached. The side stand 203 is used to maintain the posture of the body 202 when the motorcycle 200 is stopped. When the body 202 is stopped using the side stand 203, it leans slightly toward the side on which the side stand 203 is provided. Therefore, when the motorcycle 200 is stopped using the side stand 203, the side portion 223 of the rotor yoke 220 of the rotating electric machine 201 slopes downward from the opening 220a side toward the bottom 222 side.

[0070] Here, in the magnet cover 235 of the second embodiment, a plurality of drain holes 204 and slits 205 are formed in the inner flange portion 237. This is a point that differs from the first embodiment described above.

[0071] 6 is a perspective view of the magnet cover 235 in the second embodiment. The drainage holes 204 are formed in the inclined portion 51 of the inner flange portion 237. The drainage holes 204 are formed in a substantially circular shape in a plan view. The slits 205 extend radially outward from the inner peripheral edge of the abutting portion 52 of the inner flange portion 237. The slits 205 are formed between the inner peripheral edge of the abutting portion 52 of the inner flange portion 237 and the abutting portion 52 side of the inclined portion 51. The slits 205 are formed so as to gradually taper toward the inclined portion 51.

[0072] The drain holes 204 and slits 205 are formed at positions corresponding to the protruding ridges 36a of the magnet cover 235. That is, the drain holes 204 and slits 205 are arranged so as to be aligned in the axial direction with the protruding ridges 36a of the magnet cover 235. Furthermore, the drain holes 204 and slits 205 are arranged alternately in the circumferential direction.

[0073] Here, the inner circumferential surface of side portion 223 of rotor yoke 220 and the outer circumferential portion on the inner surface side of bottom portion 223 are covered by magnet cover 235. Among the areas covered by magnet cover 235, a plurality of jig holes 33 are formed in lateral wall 31b (see FIG. 3 ) of rotor yoke 220. Therefore, drainage holes 204 and slits 205 formed in magnet cover 235 communicate with jig holes 33 at a radially inner side of magnet cover 235 of rotor yoke 220.

[0074] With this configuration, for example, if water droplets enter rotor yoke 220 through opening 220a of rotor yoke 220, the water droplets will run down toward bottom 222 because side 223 of rotor yoke 220 slopes downward from opening 220a toward bottom 222. The water droplets then enter between magnet cover 235 and side 223 of rotor yoke 220 through drainage holes 204 and slits 205 formed in magnet cover 235. The water droplets are then drained to the outside of rotor yoke 220 through jig hole 33 formed in rotor yoke 220. In other words, jig hole 33 functions as a hole for inserting jig Z for positioning magnet 34, as well as a drainage hole.

[0075] Therefore, according to the second embodiment described above, in addition to the same effects as those of the first embodiment described above, even if water droplets or the like enter the rotor yoke 220, the water droplets or the like can be reliably discharged. Therefore, malfunction of the rotating electric machine 201 due to water droplets or the like can be reliably prevented, and the reliability of the rotating electric machine 201 can be improved.

[0076] Furthermore, the drainage holes 204 and the slits 205 are each arranged so as to be aligned in the axial direction with the protruding ridges 36a of the magnet cover 235. In other words, the drainage holes 204 and the slits 205 are formed in positions that do not overlap with the magnet 34 in the radial direction. Therefore, compared to when the drainage holes 204 and the slits 205 are formed in positions that overlap with the magnet 34 in the radial direction, the magnet 34 can be prevented from becoming wet.

[0077] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. For example, in the above-described embodiment, the rotating electric machine 1, 201 is attached to the engine 100 of a motorcycle 200 or the like. However, the present invention is not limited to this, and the rotating electric machine 1, 201 can be used in various devices.

[0078] In the first embodiment described above, the protrusions 31 are formed along the entire outer periphery of the bottom 22 of the rotor yoke 20. However, this is not limiting, and multiple protrusions 31 may be formed intermittently along the outer periphery of the bottom 22. This configuration allows the inertial force of the rotor yoke 20 to be adjusted. In this case, it is also desirable to arrange the protrusions 31 at equal intervals. This allows the rotational balance of the rotor yoke 20 to be maintained.

[0079] Furthermore, in the above-described first embodiment, the protrusion 31 is formed by pressing the bottom portion 22. However, this is not limited to this, and the protrusion 31 may be provided separately on the outer periphery of the bottom portion 22. Also, in the above-described first embodiment, the mounting seat 27 formed in the radial center of the bottom portion 22 is slightly shifted from the bottom portion 22 toward the crankcase 101. However, this is not limited to this, and the bottom portion 22 and the mounting seat 27 may be formed on the same plane as needed.

[0080] In the second embodiment described above, the drain holes 204 and the slits 205 are formed in the inner flange portion 237 of the magnet cover 235. Furthermore, the drain holes 204 and the slits 205 are arranged alternately in the circumferential direction in the magnet cover 235. However, this is not limited to this, and it is sufficient that the magnet cover 235 has at least one of a hole and a slit that communicates at least the radially inner side of the magnet cover 235 of the rotor yoke 220 with the jig hole 33 of the rotor yoke 220.

[0081] In the above embodiment, a case has been described in which a plurality of jig holes 33 are formed in the side wall 31b of the rotor yoke 20. The case has been described in which these jig holes 33 are used to position the magnets 34 by inserting the jig Z. However, this is not limited to this, and the jig holes 33 may be simple communication holes through which the jig Z cannot be inserted. Even in this configuration, the communication holes can function as drainage holes.

[0082] According to the outer rotor type rotating electric machine described above, by forming a convex portion on the outer peripheral surface of the bottom of the rotor yoke that protrudes toward the opposite side from the engine, the weight of the outer peripheral portion of the rotor yoke can be effectively increased compared to the radial center of the rotor yoke. As a result, the inertia force of the rotor yoke can be efficiently increased. Furthermore, since there is no need to increase the weight of the entire rotor yoke, the rotor yoke can be prevented from becoming larger. This eliminates the need to extend the crankshaft, thereby suppressing whirling of the crankshaft. Furthermore, since a cooling fan is provided on the surface of the bottom of the rotor yoke opposite the engine, there is no need to place a cooling fan between the engine and the outer rotor type rotating electric machine, and the cooling fan can be placed on the opposite side of the outer rotor type rotating electric machine from the engine. This allows the outer rotor type rotating electric machine to be made smaller and with higher performance.

[0083] DESCRIPTION OF SYMBOLS 1,201...outer rotor type rotating electric machine, 2...stator, 3...flywheel unit, 4...cooling fan, 20,220...rotor yoke, 21...rotor boss, 22,222...bottom, 22a...one surface (surface), 23,223...side, 27...mounting seat, 28...bottom side connecting portion (mounting hole), 31...protrusion, 33...jig hole (communicating hole), 34...magnet, 35...magnet cover, 36...cover main body, 37...inner flange portion, 38...outer flange portion, 51...inclined portion (inner flange portion), 52...abutment portion (inner flange portion), 100...engine, 102...crankshaft, 200...motorcycle, 202...vehicle body, 203...side stand, 204...drain hole (hole), 205...slit, 235...magnet cover, C...rotation axis, Z...jig (positioning jig)

Claims

DEPCT631. The external rotor type electric motor consists of: a stator mounted to the engine; and a rotor coupling mounted to the engine crankshaft and covering the stator on the side opposite to the engine, where the rotor coupling consists of a rotor hub mounted on and secured to the crankshaft; a disc-shaped underbody provided at the end of the rotor hub on the side opposite to the engine and constructed axially with the axis of rotation of the crankshaft; and side projections and bends on the engine side from the outer edge of the underbody, covering the outer surface of the stator and having an inner surface with many magnets arranged at equal intervals; and where projections on the side opposite to the engine are provided on the outer surface of the underbody and a cooling fan is provided on the surface of the underbody on the side opposite to the engine.

2. The external rotor type electric motor according to claim 1, where projections are constructed over the entire outer surface of the underbody.3.The electric motor rotates an outer rotor type according to claim 1 or 2, where multiple connection holes are created in a sequence corresponding to the center points between adjacent magnets of multiple magnets on the protrusions.

4. The electric motor rotates an outer rotor type according to one of claims 1 through 3, where a mounting shoulder with mounting holes connecting the base to the rotor hub is arranged radially at the center of the base, and the mounting shoulder is made such that it deflects toward the engine side from the base.

5. The electric motor rotates an outer rotor type according to claim 3, consisting of: a magnetic cover attached to the inner surface of the base at the rotor connection and a magnetic cover from the inner perimeter surface to retain the magnet, where holes allowing the inner side of the rotor connection in the radial direction to connect to the connection holes of the rotor connection are created in the magnetic cover. 6.The electric motor rotating outer rotor type according to claim 5, where the magnetic cover consists of the main body cover that encloses the inner surface of the magnet, an inner flange extending from the end of the main body cover on the side of the rotor connection base to the inner radial direction, and an outer flange extending from the end of the main body cover on the side of the rotor connection opening to the outer radial direction, and the inner flange is fixed to the inner surface of the bottom surface and holes are created in the inner flange.

7. The electric motor rotating outer rotor type according to claim 5 or 6, where holes are created at positions where the holes do not overlap the magnet radially.

8. The electric motor rotating outer rotor type according to claim 3, consists of: a magnetic cover fixed to the inner surface of the rotor connection base and a magnetic cover from the inner surface to retain the magnet, where grooves that connect the inner radial surface of the rotor connection to the rotor connection holes are created in the magnetic cover. 9.The electric motor rotates in an outer rotor configuration according to claim 8, where the magnetic cover consists of a main body cover that encloses the inner surface of the magnet, an inner flange extending from the end of the main body cover on the side of the rotor connection opening to the inner side in a radial direction, and an outer flange extending from the end of the main body cover on the side of the rotor connection opening to the outer side in a radial direction, and where the inner flange is fastened to the inner surface of the base and holes are made in the inner flange.

10. The electric motor rotates in an outer rotor configuration according to claim 8 or 9, where grooves are made at positions where the grooves do not overlap the magnet in a radial direction.11.A motorcycle consists of: an external rotor-type electric motor as specified in any one of claims 1 through 10; the chassis on which the external rotor-type electric motor is mounted; and a side stand provided on the outside of the chassis in the chassis width direction, where the external rotor-type electric motor and the side stand are mounted on the same surface of the chassis in the chassis width direction.