Starter generator and method for manufacturing the same

Abstract

The present invention provides a starter generator and a method for manufacturing the starter generator, which suppresses the increase in the number of processes and reliably discharges the sludge entering the clutch part to the outside by a simple method. The starter generator includes: a rotor having a yoke and a permanent magnet, the yoke having a cylindrical first side wall and a first bottom integrally provided with the first side wall, the permanent magnet being provided at the inner circumference of the first side wall; a flywheel having a second bottom and a cylindrical second side wall, the second bottom being provided on the side opposite to the first side wall relative to the first bottom, the second side wall extending from the second bottom to the side opposite to the first bottom; and a clutch part fixed to at least one of the second side wall and the second bottom, and the flywheel having: a recess provided at the second bottom and having an opening opening to the radially outer side of the second side wall; and a through hole formed from the inner surface of the second bottom and the second side wall toward the recess.

Description

Technical Field

[0001] The invention relates to a starter generator and a method for manufacturing the starter generator. Background Art

[0002] Conventionally, there is known a starter generator, which transmits the rotation of a stator motor to the rotating shaft of the engine in a vehicle such as an engine vehicle to start the engine, and converts the rotation energy of the engine into electric energy to charge a battery, etc. In these starter generators, the following technology is disclosed, namely, a clutch mechanism is provided coaxially with the rotating shaft of the engine, and the rotation of the stator motor is transmitted via the clutch mechanism.

[0003] For example, Patent Document 1 discloses a structure of an AC generator having a magnet rotor and a stator, wherein the magnet rotor has a yoke, and the yoke has a permanent magnet fixed to the cylindrical side and is connected to a rotating shaft. A clutch nesting portion is formed at the bottom of the yoke, and the clutch mechanism is positioned and fixed by the clutch nesting portion. According to the technology described in Patent Document 1, by providing the clutch nesting portion on the yoke, the rotor can be miniaturized.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Patent No. 4705639 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In such a generator, sludge generated by the engine may remain inside the clutch part when the generator rotates. As a method of discharging the sludge to the outside, for example, a hole penetrating in the axial direction is formed in the flywheel or the like that houses the clutch part, and the sludge is discharged from the hole.

[0009] However, when a hole penetrating in the axial direction is newly provided, an additional step for forming the hole is required, so that the number of steps increases and the manufacturing cost may increase.

[0010] Therefore, the present invention provides a starter generator and a method for manufacturing the starter generator, which can suppress an increase in the number of steps and reliably discharge sludge that has entered a clutch portion to the outside by a simple method.

[0011] Technical means of solving problems

[0012] In order to solve the above-mentioned problem, the starter generator of the present invention includes: a rotor having a yoke and a permanent magnet, the yoke having a cylindrical first side wall and a first bottom integrally provided with the first side wall, the permanent magnet being provided on the inner peripheral portion of the first side wall; a flywheel having a second bottom and a cylindrical second side wall, the second bottom being provided on the side opposite to the first side wall relative to the first bottom, the second side wall extending from the second bottom to the side opposite to the first bottom; and a clutch portion fixed to at least one of the second side wall and the second bottom, and the flywheel having: a support portion provided from the second bottom to the side opposite to the second side wall, penetrating the first bottom; a recess formed in the second bottom, between the first bottom and the second bottom, having an opening portion opening to the radially outer side of the second side wall; and a through hole extending from the inner side surface of at least one of the second bottom and the second side wall toward

[0013] The first bottom portion of the starter generator of the present invention has a ventilation hole provided at a position overlapping with the recessed portion of the second bottom portion.

[0014] The recessed portion of the starter generator of the present invention is formed in a fan shape in which the opening width in the circumferential direction increases toward the outer side in the radial direction when viewed from the axial direction of the second side wall.

[0015] The recessed portion of the starter generator of the present invention comprises: a first step portion formed at the second bottom portion; and a second step portion formed at the first step portion, the recessed depth of which is deeper than that of the first step portion.

[0016] The first step portion and the second step portion of the starter generator of the present invention both have the opening portion, and the through hole is formed in the second step portion.

[0017] The manufacturing method of the starter generator of the present invention comprises: a first step of forming the second side wall and the second bottom having the recess by any one of forging and casting; and a second step of forming the through hole by cutting the second bottom from the second side wall after the first step.

[0018] Effects of the Invention

[0019] According to the present invention, a starter generator and a method for manufacturing the starter generator can be provided, which can suppress an increase in the number of steps and reliably discharge sludge that has entered a clutch mechanism to the outside by a simple method. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of the starter generator according to the first embodiment.

[0021] Figure 2 It is a perspective view of the yoke of the first embodiment.

[0022] Figure 3 It is a perspective view of the flywheel of the first embodiment.

[0023] Figure 4 for Figure 3 A top view of the second bottom portion of Part IV.

[0024] Figure 5 It is a cross-sectional view of the flywheel of the first embodiment.

[0025] Figure 6 It is a cross-sectional view of a flywheel according to the second embodiment.

[0026] Figure 7 It is a cross-sectional view of a flywheel according to a third embodiment.

[0027] [Explanation of Symbols]

[0028] 1: Start the generator;

[0029] 2: rotor;

[0030] 3: Flywheel;

[0031] 4: Clutch unit;

[0032] 20: yoke;

[0033] 21: Permanent magnet;

[0034] 22: first side wall;

[0035] 23: First bottom;

[0036] 27: Ventilation holes;

[0037] 31: second side wall;

[0038] 32: second bottom;

[0039] 33: Pillar section;

[0040] 34: concave part;

[0041] 36: First stage;

[0042] 36a: first opening (opening);

[0043] 37: Second stage;

[0044] 37a: second opening (opening);

[0045] 38: Through hole. DETAILED DESCRIPTION

[0046] Next, embodiments of the present invention will be described based on the drawings.

[0047] (First Embodiment)

[0048] (Starting generator)

[0049] Figure 1 It is a cross-sectional view of the starter generator 1 according to the first embodiment.

[0050] The starter generator 1 is an outer rotor type generator and includes: a rotor 2 that rotates integrally with the rotating shaft 11 of the engine; a stator 12 that is arranged on the inner side of the rotor; a flywheel 3 that is connected to the rotor 2 and rotates integrally with the rotating shaft 11 of the engine; a clutch part 4 that is arranged on the inner side of the flywheel 3; and a connecting member 5 that connects the rotor 2 and the flywheel 3.

[0051] (Rotor)

[0052] The rotor 2 is formed into a cylindrical shape centered on an axis C coaxial with the engine rotating shaft 11. In the following description, the direction along the axis C of the rotor 2 is referred to as an axial direction, the direction orthogonal to the axis C is referred to as a radial direction, and the direction around the axis C is referred to as a circumferential direction.

[0053] The rotor 2 includes a yoke 20 and a permanent magnet 21 disposed inside the yoke 20 .

[0054] Figure 2 It is a perspective view of the yoke 20 according to the first embodiment.

[0055] like Figure 1 and Figure 2 As shown, the yoke 20 is formed into a bottomed cylindrical shape, and has: a cylindrical first side wall 22, centered on the axis C; and a first bottom 23, which is integrally provided with the first side wall 22 and covers the opening of the first side wall 22 on the engine side. On the first side wall 22, a protrusion 22a is provided radially outward by pressing, and this protrusion 22a is used to detect the rotation position of the rotor 2 and the rotating shaft 11. The first bottom 23 of the yoke 20 is formed into a ring shape with an insertion hole 25 in the center. The insertion hole 25 is provided coaxially with the axis C. In addition to the insertion hole 25, the first bottom 23 also has a first connecting hole 26 and a ventilation hole 27. The first connecting hole 26 is provided radially outward of the insertion hole 25, and penetrates the first bottom 23 in the axial direction. A plurality of first connecting holes 26 are provided in the circumferential direction (six in this embodiment). A plurality of ventilation holes 27 are provided in the circumferential direction (six in this embodiment). The ventilation hole 27 penetrates the first bottom 23 in the axial direction.

[0056] like Figure 1As shown, permanent magnets 21 are fixed to the inner circumference 24 of the first side wall 22 of the yoke 20. A plurality of permanent magnets 21 are provided in the circumferential direction, and each permanent magnet 21 is magnetized so that magnetic poles are alternately arranged in the circumferential direction.

[0057] On the radial inner side of the permanent magnet 21, a stator 12 is arranged at a distance from the permanent magnet 21. The stator 12 is fixed to the housing (not shown) of the engine, for example. A coil (not shown) is wound around the stator 12. The winding end of the coil is electrically connected to a battery or electrical parts (not shown) carried by the vehicle body. The rotor 2 rotates relative to the stator 12, thereby generating current in the coil, charging the battery or supplying power to the electrical parts.

[0058] (flywheel)

[0059] A flywheel 3 is arranged on the engine side of the rotor 2 in the axial direction. The flywheel 3 is formed in a cylindrical shape and has: a cylindrical second side wall 31 centered on the axis C; a second bottom 32 covering the opening of the second side wall 31 on the rotor 2 side; and a support portion 33 protruding from the second bottom 32 to the rotor 2 side. The second bottom 32 of the flywheel 3 faces the first bottom 23 of the rotor 2, and the second bottom 32 and the axially outer end surfaces of the second bottom 32 abut against each other. The support portion 33 of the flywheel 3 is formed integrally with the second bottom 32. The support portion 33 protrudes from the center of the second bottom 32 to the rotor 2 side and is formed in a cylindrical shape coaxial with the axis C. The support portion 33 is inserted into the insertion hole 25 of the rotor 2. The support portion 33 has a shaft insertion hole 33a at the center, and the inner shape of the shaft insertion hole 33a is a tapered hole, that is, it is inclined in a manner of decreasing the diameter toward the rotor 2 side in contrast to the shape of the top end of the rotating shaft 11. The support portion 33 has an external thread 33 b formed at a tip portion of the rotating shaft 11 protruding toward the rotor 2 , and the support portion 33 and the rotating shaft 11 are fixed by the nut 13 so as to rotate together around the axis C.

[0060] Figure 3 It is a perspective view of the flywheel 3 according to the first embodiment. Figure 4 for Figure 3 A top view of the second bottom portion 32 of portion IV. Figure 5 It is a cross-sectional view of the flywheel 3 according to the first embodiment.

[0061] like Figure 3 As shown, the second bottom 32 of the flywheel 3 has: a recess 34 that is recessed from the second bottom 32 toward the second side wall 31; and a second connecting hole 35 and a third connecting hole 45 that penetrate the second bottom 32 in the axial direction.

[0062] The recessed portion 34 is provided in a plurality (three in this embodiment) in the circumferential direction. The recessed portion 34 is provided at a position overlapping with the ventilation hole 27 provided in the first bottom portion 23 of the yoke 20 in the circumferential direction (see Figure 1The recess 34 is provided in the second bottom portion 32 at the interface with the first bottom portion 23 of the rotor 2. Figure 4 and Figure 5 As shown, the recessed portion 34 has: a first step portion 36 formed at the second bottom portion 32; and a second step portion 37 formed at the first step portion 36, and having a deeper recessed depth than the first step portion 36. The recessed depth h1 of the first step portion 36 is less than the plate thickness t of the second bottom portion 32 (h1<t). The recessed depth h2 of the second step portion 37 is greater than the plate thickness t of the second bottom portion 32 (h2>t).

[0063] like Figure 4 As shown, the first step portion 36 is formed in a substantially fan-shaped shape in which the opening width in the circumferential direction increases toward the radially outer side when viewed from the axial direction.

[0064] The first step 36 has a first opening 36a that opens radially outward. Thus, when the second bottom 32 of the flywheel 3 abuts against the first bottom 23 of the rotor 2 and the recess 34 is blocked from the axial direction, the internal space formed by the first step 36 communicates with the outside of the flywheel 3 via the first opening 36a.

[0065] The second step portion 37 is located inside the first step portion 36 when viewed from the axial direction. The second step portion 37 is formed in a similar shape to the first step portion 36 when viewed from the axial direction. Specifically, the second step portion 37 is formed in a fan shape whose opening width in the circumferential direction increases as it goes radially outward, and is formed in such a way that one side of the fan shape located in the radial direction is in the same position as one side of the first step portion 36 located in the radial direction.

[0066] The second step 37 has a second opening 37a that opens radially outward. The length dimension of the second opening 37a in the circumferential direction is smaller than the length dimension of the first opening 36a in the circumferential direction. In a state where the second bottom 32 of the flywheel 3 abuts against the first bottom 23 of the rotor 2 and the recess 34 is blocked from the axial direction, the internal space formed by the second step 37 communicates with the outside of the starter generator 1 via the second opening 37a. The second opening 37a communicates with the first opening 36a in the axial direction.

[0067] A through hole 38 is provided at the radially inner end of the second step 37. The through hole 38 penetrates the second step 37 in the axial direction. The through hole 38 is a hole that penetrates the second bottom 32 because the recessed depth h2 of the second step 37 is greater than the plate thickness of the second bottom 32. Figure 1 and Figure 5As shown in FIG. 1 , the through hole 38 is formed by opening from the second side wall 31 or the inner surface of the second bottom 32 toward the recess 34, with the distance h2 from the surface of the side where the support portion 33 of the second bottom 32 protrudes to the bottom surface of the second step portion 37 being greater than the distance t from the surface of the inner side of the second bottom 32 (the side where the clutch portion is mounted) to the surface of the side where the support portion 33 of the second bottom 32 protrudes. Figure 4 As shown, the through hole 38 is provided in the entire area of ​​the second step portion 37 located radially inward of the inner circumferential surface 30 of the second side wall 31. In this embodiment, the through hole 38 is formed in a semicircular shape corresponding to the shape of the end of the second step portion 37 when viewed from the axial direction.

[0068] like Figure 3 As shown, two second connection holes 35 are provided between adjacent recesses 34 in the circumferential direction (i.e., six in total). The third connection hole 45 is provided between two second connection holes 35 provided between adjacent recesses 34 in the circumferential direction. That is, three third connection holes 45 are provided in total.

[0069] (Clutch part)

[0070] Back to Figure 1 A clutch unit 4 is provided on the inner circumference of the second side wall 31 of the flywheel 3. The clutch unit 4 includes: an annular outer ring 43 fixed to the second bottom portion 32 by bolts or the like; and a one-way clutch 41 disposed radially inward of the outer ring 43.

[0071] The outer ring 43 is press-fitted into the flywheel 3 and fastened with bolts or the like inserted into the third fastening holes 45 of the second bottom portion 32 , thereby being fixed to the flywheel 3 .

[0072] The one-way clutch 41 includes a plurality of cylindrical bearings, which are arranged in the circumferential direction relative to the inner circumferential side of the outer ring 43 and supported to be rotatable in the axial direction. The clutch part 4 supports a stator meshing gear part 44, which includes: a cylindrical member supported on the inner circumference of the one-way clutch 41; and a disc member, which is formed integrally with the cylindrical member and has a gear part formed on the outer circumference to mesh with the output gear of the stator motor (not shown).

[0073] Furthermore, the outer ring 43 may be provided with a groove or the like that communicates from the radial inside to the outside for releasing sludge generated by the engine from the one-way clutch 41 .

[0074] (Connecting parts)

[0075] In a state where the first bottom 23 of the rotor 2 is in contact with the second bottom 32 of the flywheel 3, the connecting member 5 connects the first bottom 23 and the second bottom 32. Specifically, the connecting member 5 is a fastening member such as a rivet. The connecting member 5 is inserted into the first connecting hole 26 and the second connecting hole 35 and fastened (riveted), thereby connecting the yoke 20 and the flywheel 3. As a result, the yoke 20 rotates integrally with the flywheel 3.

[0076] In addition, the connecting member 5 may be a fastening member such as a bolt and a nut, or a member welded by welding or heat caulking, etc. Furthermore, instead of using a fastening member, serrations may be formed on the outer peripheral surface of the support portion 33 of the flywheel 3, and the inner peripheral surface of the insertion hole 25 of the rotor 2 and the support portion 33 may be fixed by engagement.

[0077] (Manufacturing method of starter generator)

[0078] Next, a method for manufacturing the starter generator 1 will be described.

[0079] The manufacturing method of the starter generator includes: a first step of forming a second side wall 31 and a second bottom 32 having a recess 34 by forging or casting; a second step of forming a through hole 38 by cutting the second bottom 32 from the side of the second side wall 31 after the first step; and a third step of connecting the flywheel 3 to the rotor 2 after the second step.

[0080] In the present embodiment, in the first step, the flywheel 3 is first formed by forging. Figure 5 As shown by the two-dot chain line, during the forging process, the outer shape of the flywheel 3 is formed in such a way that the thickness of the second side wall 31, the second bottom 32 and the support part 33 of the flywheel 3 is greater than the design value. Specifically, the radial thickness and axial length of the second side wall 31, the axial thickness of the second bottom 32, and the radial thickness of the support part 33 are respectively greater than the design value. In addition, by providing a convex portion at a position corresponding to the concave portion 34 on the die of the forging process, for example, a second bottom 32 having the concave portion 34 is formed.

[0081] In a state where the first step is completed, the pre-cutting thickness Tf of the second bottom portion 32 is greater than the maximum depth h2 of the recessed portion 34 (Tf>h2).

[0082] Next, in the second step, in order to manufacture the inner diameter dimension of the flywheel 3, a tool such as an end mill or a lathe is inserted axially from the second side wall 31 side of the flywheel 3, thereby performing a removal process on the inner circumference of the flywheel 3. Specifically, the axial end face of the second side wall 31, the inner circumferential surface 30 of the second side wall 31, and the inner end face of the second bottom 32 are cut. At this time, the cutting is performed until the inner circumferential surface 30 of the second side wall 31 is located radially outward relative to the radial inner end of the second step 37. Furthermore, the cutting is performed until the thickness of the second bottom 32 is smaller than the depth dimension h2 of the second step 37. By performing the axial removal process in this way, a through hole 38 that connects the space inside the second side wall 31 with the recess 34 is formed.

[0083] Furthermore, at this time, the second connection hole 35 is formed by cutting.

[0084] Moreover, for example, after cutting with an end mill or the like, the flywheel 3 can be rotated at a high speed while the support portion 33 of the flywheel 3 is fixed with a chuck or the like, so that the tool contacts the inner periphery of the flywheel 3 for turning, thereby finishing the inner periphery and forming a through hole 38 from the inner side of the second side wall 31 or the second bottom 32 (the side on which the clutch portion 4 is installed) toward the recessed portion 34.

[0085] In addition, the second connection hole 35 may also be formed by the forging process in the first step.

[0086] In the third step, the flywheel 3 formed in the first and second steps is connected to the rotor 2. Specifically, the first bottom 23 and the second bottom 32 are brought into contact with each other, and the connecting member 5 is inserted into the first connecting hole 26 and the second connecting hole 35, thereby fastening and fixing the flywheel 3 and the rotor 2.

[0087] In this way, the starter generator 1 is manufactured through the first step, the second step, and the third step.

[0088] Moreover, after the first step, the surface on the support portion 33 side of the second bottom portion 32 may be cut in a second step, and after the flywheel 3 and the rotor 2 are fixed in a third step, the inner surface of the second bottom portion 32 (the side on which the clutch portion 4 is installed) may be processed by turning or the like to manufacture a starter generator 1 having a flywheel 3 and a rotor 2 with a through hole 38 formed on the inner surface of the second side wall 31 or the second bottom portion 32.

[0089] (Function, Effect)

[0090] Next, the operation and effects of the starter generator 1 and the method for manufacturing the starter generator will be described.

[0091] According to the starter generator 1 of the present invention, a clutch portion 4 is provided on the inner periphery of the flywheel 3, so that the flywheel 3 is driven in a prescribed direction, for example, by a stator motor (not shown) connected to the stator meshing gear portion 44. Thus, the engine of the vehicle can be started. In addition, a support portion 33 is formed on the second bottom portion 32 of the flywheel 3, the support portion 33 passes through the first bottom portion 23, and the connecting member 5 connects the first bottom portion 23 and the second bottom portion 32, thereby connecting the yoke 20 to the flywheel 3. Thereby, the flywheel 3 rotates integrally with the yoke 20. Therefore, by rotating the yoke 20 relative to the stator 12 arranged on the inner periphery of the yoke 20, a charger or the like carried by the vehicle can be charged.

[0092] The second bottom portion 32 has a recess 34, and a through hole 38 is formed in the recess 34, which penetrates the second side wall 31 or the inner surface of the second bottom portion 32 in the axial direction and the radial direction, so that the sludge generated by the clutch portion 4 when the starter generator 1 rotates is Figure 1 As shown by the arrow A, the sludge moves from the inner side (clutch unit 4 mounting side) of the second bottom portion 32 through the through hole 38 to the recess 34 of the flywheel 3. Furthermore, the recess 34 has a first opening 36a and a second opening 37a that are opened radially outward, so that the sludge moved to the recess 34 moves radially outward of the recess 34 due to centrifugal force and is discharged to the outside of the starter generator 1 due to the centrifugal force. Therefore, the sludge that has entered the clutch unit 4 can be reliably discharged to the outside, and the performance reduction of the starter generator 1 caused by the sludge being retained in the clutch unit 4 can be suppressed.

[0093] Furthermore, the recessed direction of the recessed portion 34 and the penetrating direction of the through hole 38 are formed in a manner along the axial direction of the flywheel 3, so that the recessed portion 34 and the through hole 38 can be formed by processing from the axial direction. In particular, when holes other than the through hole 38 such as the second connecting hole 35 are formed in the flywheel 3 by cutting, these processes can be coaxially performed with the processing of the through hole 38. Therefore, compared with the conventional technology of forming a hole penetrating the flywheel 3 in the radial direction for discharging sludge, the processing equipment can be simplified, and the hole for discharging sludge can be easily formed.

[0094] Therefore, it is possible to provide a starter generator 1 that suppresses an increase in the number of steps and that reliably discharges the sludge that has entered the clutch portion 4 to the outside by a simple method.

[0095] The first bottom portion 23 of the yoke 20 is provided with a ventilation hole 27 at a position overlapping with the recess 34, so that air introduced for cooling the stator 12 or the like is blown toward the recess 34 through the ventilation hole 27 and discharged to the outside of the starter generator 1 through the recess 34. Therefore, the heat generated by the stator 12 or the rotor 2 can be efficiently discharged to the outside, and the performance degradation of the starter generator 1 due to the heat can be suppressed.

[0096] When viewed from the axial direction, the recess 34 is formed in a fan shape with the opening width in the circumferential direction increasing from the radial inside to the radial outside, so that the sludge that moves into the recess 34 through the through hole 38 is easily moved radially outward by centrifugal force. Therefore, the sludge can be discharged to the outside more reliably by centrifugal force.

[0097] Since the recessed portion 34 is divided into the first step portion 36 and the second step portion 37, the amount of processing required when forming the recessed portion 34 can be reduced compared to the case where a single recessed portion 34 with a deep recessed depth is formed. Therefore, the rigidity of the flywheel 3 can be maintained high.

[0098] The first step portion 36 has a first opening portion 36a, and the second step portion 37 has a second opening portion 37a, so that the sludge moved into the recessed portion 34 can be reliably discharged from the opening portions 36a and 37a to the outside of the starter generator 1. In addition, the through hole 38 is formed in the second step portion 37 having a deeper recessed depth than the first step portion 36, so that the processing amount of the flywheel 3 can be reduced and the through hole 38 can be easily formed.

[0099] According to the method for manufacturing a starter generator according to the aspect of the present invention, the method for manufacturing a starter generator includes a first step and a second step.

[0100] In the first step, the second side wall 31 and the second bottom 32 having the recessed portion 34 are formed by forging or casting. In this way, in the first step, the second side wall 31 and the second bottom 32 can be formed together by forging or casting. In a state where the first step is completed, the recessed portion 34 is formed in the second bottom 32. Therefore, the recessed portion 34 can be easily formed.

[0101] In the second process, after the first process, the second bottom portion 32 is cut from the second side wall 31 to form the through hole 38. Here, for example, when the clutch portion 4 is arranged on the inner peripheral portion of the second side wall 31, it is necessary to perform finishing of the inner peripheral portion of the second side wall 31 by cutting. In the finishing, the second side wall 31 is cut from the second side wall 31 so as to reduce the thickness of the second bottom portion 32 of the flywheel 3, so that the radial inner space of the second side wall 31 is connected to the recess 34 provided in the second bottom portion 32. The hole formed in this way can be used as the through hole 38, and the sludge and the like that has entered the clutch portion 4 can be discharged to the outside through the through hole 38. Therefore, it is not necessary to form the through hole 38 by separate processing, and the manufacturing process can be simplified.

[0102] In this way, by going through the first step and the second step, it is possible to provide a method for manufacturing a starter generator, which can suppress an increase in the number of steps and reliably discharge the sludge that has entered the clutch portion 4 to the outside by a simple method.

[0103] (Second Embodiment)

[0104] Next, based on Figure 6 A starter generator 1 according to a second embodiment will be described. In the starter generator 1 according to the second embodiment, components identical or similar to those of the starter generator 1 according to the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0105] Figure 6 It is a cross-sectional view of the flywheel 3 according to the second embodiment.

[0106] The second embodiment is different from the first embodiment in that the recessed portion 34 does not have the second step portion 37 .

[0107] In the second embodiment, a recess 234 is formed in the second bottom portion 32. The recess 234 is formed by a single step portion having a recess depth h3 greater than the plate thickness t of the second bottom portion 32 (t<h3). The radial inner end of the recess 234 is located radially inward of the inner circumferential surface 30 of the second side wall 31. The recess 234 has a through hole 238. The through hole 238 penetrates the second bottom portion 32 in the axial direction.

[0108] According to the starter generator 1 of the second embodiment, the recessed portion 234 has a single step portion, so that the structure of the die used in the forging process can be simplified compared to the case where the recessed portion 234 has a plurality of steps.

[0109] (Third Embodiment)

[0110] Next, based on Figure 7 A starter generator 1 according to a third embodiment will be described. In the starter generator 1 according to the third embodiment, components identical or similar to those of the starter generators 1 according to the first and second embodiments are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0111] Figure 7 It is a cross-sectional view of a flywheel 3 according to a third embodiment.

[0112] The third embodiment is different from the first embodiment in that the recessed portion 34 has a tapered surface.

[0113] In the third embodiment, a recessed portion 334 is formed in the second bottom portion 32. The recessed portion 334 has a tapered surface 339 whose depth gradually increases from the axially outer end surface of the second bottom portion 32 toward the bottom surface 334a of the recessed portion 334. A through hole 338 is formed at the boundary portion between the bottom surface 334a of the recessed portion 334 and the tapered surface 339. The through hole 338 penetrates the second bottom portion 32 in the axial direction.

[0114] According to the starter generator 1 of the third embodiment, since the recessed portion 334 has the tapered surface 339, the removability of the die can be improved during the forging process. Therefore, the starter generator 1 can be provided with excellent manufacturability.

[0115] The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. The addition, omission, substitution and other changes of the structure can be made within the scope of not departing from the gist of the present invention. The present invention is not limited by the description described above, but only by the attached claims.

[0116] For example, in the above-described embodiment, the recess 34 is formed in a fan-shaped structure when viewed from the axial direction, but the present invention is not limited thereto. That is, when viewed from the axial direction, the recess 34 may be formed in a shape other than the fan-shaped shape, such as a triangle, a rectangle, or a semicircle. However, the fan-shaped shape is superior to the rectangular shape in that the width of the openings 36a and 37a can be ensured to be large in the circumferential direction.

[0117] The support part 33 and the second bottom part 32 may be formed separately. That is, the support part 33 and the flywheel 3 may be formed separately and then integrated with the second bottom part 32 of the flywheel 3 by fastening or press-fitting.

[0118] In the above embodiment, the first step portion 36 and the second step portion 37 are both provided with the openings 36a and 37a, but one of them may not have an opening. That is, when the first step portion 36 is provided with the first opening 36a, the second opening 37a may not exist. When the second step portion 37 is provided with the second opening 37a, the first opening 36a may not exist.

[0119] The number of steps provided in the recessed portion 34 is not limited to the above-described embodiment.

[0120] The through hole 38 may be formed in the first step. That is, the forging process may be performed so that the maximum plate thickness h2 of the recessed portion 34 is larger than the plate thickness Tf before cutting (h2>Tf), and then the diameter of the through hole 38 may be expanded by cutting in the second step.

[0121] The flywheel 3 may be formed by casting in the first step.

[0122] Furthermore, structural elements of the embodiments may be appropriately replaced with well-known structural elements within the scope not departing from the gist of the present invention, and the embodiments may be appropriately combined.

Claims

1. A starter generator, characterized in that: include: A rotor having a yoke and a permanent magnet, wherein the yoke has a cylindrical first side wall and a first bottom integrally provided on the first side wall, and the permanent magnet is provided on the inner circumference of the first side wall; The flywheel has a second bottom and a second cylindrical side wall, wherein the second bottom is arranged on a side opposite to the first side wall relative to the first bottom, and the second side wall extends from the second bottom to a side opposite to the first bottom. a clutch portion fixed to at least one of the second side wall and the second bottom portion, and The flywheel comprises: a support portion, which is provided from the second bottom to the side opposite to the second side wall and penetrates the first bottom; a recessed portion, which is formed in the second bottom and between the first bottom and the second bottom, and has an opening portion which opens to the radially outer side of the second side wall; and a through hole formed from an inner surface of at least one of the second bottom portion and the second side wall toward the recessed portion.

2. The starter generator according to claim 1, characterized in that: The first bottom portion has a ventilation hole provided at a position overlapping with the recessed portion of the second bottom portion.

3. The starter generator according to claim 1 or 2, characterized in that: The recessed portion is formed in a fan shape in which an opening width in the circumferential direction increases toward the outer side in the radial direction when viewed from the axial direction of the second side wall.

4. The starter generator according to claim 3, characterized in that: The recess has: A first step portion formed at the second bottom portion; and The second step portion is formed on the first step portion and has a deeper recess than the first step portion.

5. The starter generator according to claim 4, characterized in that: The first step portion and the second step portion both have the opening portion, The through hole is formed in the second step portion.

6. The starter generator according to claim 1 or 2, characterized in that: The recess has: A first step portion formed at the second bottom portion; and The second step portion is formed on the first step portion and has a deeper recess than the first step portion.

7. The starter generator according to claim 6, characterized in that: The first step portion and the second step portion both have the opening portion, The through hole is formed in the second step portion.

8. A method for manufacturing a starter generator, manufacturing the starter generator according to any one of claims 1 to 7, characterized in that: include: A first step is to form the second side wall and the second bottom having the concave portion by either forging or casting. as well as The second step is to form the through hole by cutting the second bottom portion from the second side wall side after the first step.

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