Drive unit and power-assisted bicycle

Abstract

To provide a drive unit which can effectively use a plate-like member, and to provide a power-assisted bicycle including the drive unit.SOLUTION: A drive unit 38 of a power-assisted bicycle 10 includes: a housing 48; a crank shaft 50 which penetrates through a first wall part 62 and a second wall part 64 of the housing 48 and is rotatably supported by the housing 48; a motor 52 provided within the housing 48; a plate-like member 54 which is provided within the housing 48 so as to cover at least a part of the motor 52 and fixed to the housing 48; and a speed reduction mechanism 56 provided between the plate-like member 54 and the second wall part 64 in the housing 48. The plate-like member 54 has a protruding part 130 protruding to the outside of the motor 52 when viewed from an axial direction of the crank shaft 50. The speed reduction mechanism 56 includes a first speed reducer 150 rotatably supported by the plate-like member 54 and the second wall part 64 so that a rotation axis X1 is located in the protruding part 130 when viewed from the axial direction of the crank shaft 50.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a drive unit and an electrically assisted bicycle, and more particularly to a drive unit having a motor and an electrically assisted bicycle including the same. [Background technology]

[0002] As an example of this type of prior art, Patent Document 1 discloses a drive unit that is attached to the body frame of an electrically assisted bicycle and generates driving force that is transmitted to the wheel. This drive unit includes a housing, an electric motor disposed within the housing, a pedal crankshaft that penetrates the housing in the left-right direction of the electrically assisted bicycle, and a reducer that slows down the rotation generated by the electric motor. The housing includes a first case having a recess that houses the electric motor, a second case that, together with the first case, forms the outer shell of the housing, and an inner lid that covers at least a portion of the electric motor housed in the recess of the first case. The inner lid rotatably supports the gear rotation shaft of the reducer, and its outer peripheral edge passes between the gear rotation shaft and the pedal crankshaft. The recess of the first case has a wall that follows the periphery of the electric motor, and the wall supports the inner lid. When the inner lid is viewed from a direction parallel to the output shaft of the electric motor, the outer peripheral edge of the inner lid follows the periphery of the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-62689 Summary of the Invention [Problem to be solved by the invention]

[0004] In the drive unit disclosed in Patent Document 1, the inner lid is supported by the wall of the recess, which is a highly rigid part, thereby preventing misalignment of the inner lid. This prevents misalignment of the gear rotation shaft of the reducer supported by the inner lid. Furthermore, because the inner lid does not extend toward the pedal crankshaft and is small in size, the rigidity of the inner lid can be increased. This also prevents misalignment of the gear rotation shaft of the reducer supported by the inner lid.

[0005] In this way, the drive unit can maintain the rigidity of the interior of the drive unit, but Patent Document 1 does not mention anything about making effective use of the inner lid by forming the outer edge of the inner lid to extend beyond the periphery of the electric motor.

[0006] SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide a drive unit and an electrically assisted bicycle including the same that can effectively utilize plate-shaped members. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, there is provided a drive unit comprising: a housing having a first wall portion and a second wall portion facing the first wall portion; an input shaft penetrating the first wall portion and the second wall portion and rotatably supported by the housing; a motor provided within the housing; a plate-shaped member provided within the housing so as to cover at least a portion of the motor and fixed to the housing; and a reduction mechanism provided within the housing between the plate-shaped member and the second wall portion to reduce the rotation generated by the motor, wherein the plate-shaped member has a protruding portion that protrudes outward from the motor when viewed in the axial direction of the input shaft, and the reduction mechanism includes a first reducer rotatably supported by the plate-shaped member and the second wall portion so that the rotation axis is located at the protruding portion when viewed in the axial direction of the input shaft.

[0008] In this invention, by fixing a plate-shaped member that covers at least a portion of the motor to the housing, the plate-shaped member functions as a reinforcing member for the housing, thereby substantially improving the rigidity of the housing. Furthermore, the first reducer is rotatably supported by the plate-shaped member and the second wall portion so that the rotational axis of the first reducer is located in the protruding portion that does not cover the motor when viewed in the axial direction of the input shaft. Therefore, the rotational axis of the first reducer can be relatively far from the rotational axis of the motor, improving the degree of freedom in layout of the reduction mechanism. In this way, the plate-shaped member can be effectively utilized.

[0009] Preferably, the protruding portion has an unsupported portion that is not supported by the housing, and the drive unit further includes a wiring space provided between the unsupported portion and the first wall portion. In this case, by utilizing the unsupported portion of the protruding portion, the wiring space can be easily provided between the unsupported portion and the first wall portion. By passing the wiring through the wiring space, the wiring can be kept away from gears and the like of the first reducer. Therefore, the plate-shaped member can prevent the wiring from floating and coming into contact with or getting entangled in gears and the like, without providing a new separate member.

[0010] Preferably, the unsupported portion has a first recess facing the first wall portion, in which case a bent portion of the wiring, a coupler, etc. can be accommodated in the first recess of the unsupported portion.

[0011] More preferably, the first wall portion has a second recess portion facing the first recess portion, in which case a large wiring space can be formed by the first recess portion and the second recess portion facing each other.

[0012] Preferably, the wiring space overlaps with a line segment connecting the axis of the input shaft and the rotation axis of the first reducer when viewed in the axial direction of the input shaft. In this case, by passing the wire through the wiring space, it is possible to route the wire over the shortest distance.

[0013] Preferably, the drive unit further includes a torque sensor disposed within the housing near the input shaft for detecting torque transmitted to the input shaft, and the protruding portion is provided so as to be able to come into contact with the torque sensor to function as a rotation stopper for the torque sensor. In this case, the torque sensor rotation stopper can be easily configured simply by expanding the protruding portion so as to be able to come into contact with the torque sensor, and the protruding portion can smoothly restrict rotation of the torque sensor. Furthermore, the height of the protruding portion is highly flexible in the axial direction of the input shaft, improving design freedom.

[0014] More preferably, the drive unit further includes a circuit board disposed within the housing between the plate-shaped member and the second wall portion and fixed to at least the protruding portion. In this case, the circuit board can be fixed to the protruding portion by utilizing the free space within the housing, and the plate-shaped member can be used to fix the board. This also allows for grounding. Furthermore, by using the plate-shaped member to fix the board, it is not necessary to provide a boss for fixing the board on the housing. This allows for more space for wiring and allows for a smaller housing.

[0015] Preferably, the drive unit further includes a circuit board disposed within the housing between the plate-shaped member and the second wall and thermally connected to the protruding portion. In this case, the circuit board can be thermally connected to the protruding portion by utilizing the free space within the housing, allowing the plate-shaped member to function as a heat dissipation portion. Therefore, a heat dissipation member need not be provided on the circuit board, or the heat dissipation member provided on the circuit board can be made smaller. As a result, the degree of freedom in arranging electronic components can be improved, and the housing can be made smaller.

[0016] Preferably, the plate-like member has a bearing support portion provided coaxially with the rotational axis of the first reducer, and the drive unit further has a bearing interposed between the first reducer and the bearing support portion. In this case, at least a portion of the bearing support portion is located in the protruding portion of the plate-like member, and the bearing support portion can support a bearing for rotatably supporting the first reducer.

[0017] More preferably, the protruding portion has a through hole, the first wall portion has a third recess at a position corresponding to the through hole, and the drive unit further has a knock pin inserted into the through hole and the third recess. In this case, inserting the knock pin into the through hole of the protruding portion and the third recess of the first wall portion can contribute to fixing the plate-like member to the housing.

[0018] Preferably, the reduction mechanism further includes a second reducer rotatably supported by the plate-like member and the second wall portion to reduce the rotation generated by the motor and transmit the reduced rotation to the first reducer. In this case, the first reducer and the second reducer, i.e., the plurality of reducers, can be rotatably supported by the plate-like member and the second wall portion.

[0019] Preferably, the input shaft has a first end and a second end opposite the first end where the drive sprocket is located, and the motor is located on the first end side when viewed from a direction perpendicular to the axial direction of the input shaft. This invention is suitable when the motor and the drive sprocket are located on opposite sides of the axial direction of the input shaft.

[0020] The drive unit according to the present invention can be suitably used in an electrically assisted bicycle. [Effects of the Invention]

[0021] According to the present invention, it is possible to obtain a drive unit and an electrically assisted bicycle including the same, which can effectively utilize plate-shaped members. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a side view showing an electrically assisted bicycle including a drive unit according to one embodiment of the present invention. [Figure 2] FIG. 2 is a front perspective view showing the drive unit. [Figure 3] FIG. [Figure 4]FIG. 2 is a left side view showing the drive unit. [Figure 5] FIG. 2 is a plan view showing the drive unit. [Figure 6] FIG. 5 is a cross-sectional diagram of line AA shown in FIG. [Figure 7] FIG. 2 is a diagram showing a state in which the motor is housed in the first case. [Figure 8] 8 is a diagram showing a state in which a crankshaft, a torque sensor, etc. are attached to the first case of FIG. 7. FIG. [Figure 9] 9 is a diagram showing a state in which a plate-shaped member is attached to the first case of FIG. 8. FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] 10 is a diagram showing a state in which a circuit board and the like are attached to the first case of FIG. 9. FIG. [Figure 14] 14 is a diagram showing a state in which an output shaft, a reduction mechanism, etc. are attached to the first case of FIG. 13. FIG. [Figure 15] 10A and 10B are diagrams showing modified examples of the plate-shaped member; [Figure 16] 10A and 10B are diagrams illustrating modified examples of the plate-shaped member and the torque sensor. [Figure 17] 10A and 10B are diagrams showing modified examples of the plate-like member and the circuit board; [Figure 18] 10A and 10B are diagrams showing other modified examples of the plate-shaped member and the circuit board. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] In the embodiment of the present invention, the front, rear, left, right, and top and bottom of the drive unit 38 refer to the front, rear, left, right, and top and bottom when the drive unit 38 is mounted on the power-assisted bicycle 10. In the drawings, "Fr" indicates the front, "Rr" indicates the rear, "R" indicates the right, "L" indicates the left, "U" indicates the top, and "Lo" indicates the bottom.

[0025] 1, an electrically assisted bicycle 10 according to one embodiment of the present invention includes a frame 12. The frame 12 includes a bottom bracket 14, a down tube 16, a seat post 18, a pair of seat stays 20, a pair of chain stays 22, a head tube 24, and a front fork 26.

[0026] A down tube 16 curves and extends diagonally upward and forward from the bottom bracket 14, a seat post 18 extends upward from the bottom bracket 14 at a slight rearward tilt, and a pair of chain stays 22 extend rearward from the bottom bracket 14. A pair of seat stays 20 connect the upper part of the seat post 18 to the rear ends of the pair of chain stays 22. A head tube 24 is connected to the front end of the down tube 16. A front fork 26 is rotatably inserted through the head tube 24 and is provided so as to be tilted slightly rearward.

[0027] A handlebar stem 28 is attached to the upper end of the front fork 26, and a handlebar 30 is supported by the handlebar stem 28. A saddle 32 is supported by the seat post 18. A front wheel 34 is rotatably supported by the lower end of the front fork 26, and a rear wheel 36 is rotatably supported by the rear ends of the pair of chain stays 22.

[0028] A drive unit 38 is attached to the bottom bracket 14. Details of the drive unit 38 will be described later.

[0029] A pair of crank arms 40 are attached to both ends of a crank shaft 50 (described below), i.e., a first end 82a and a second end 82b (described below). Pedals 42 are attached to the end of each crank arm 40. A drive sprocket 44 is attached to an end (in this embodiment, the right end) of an output shaft 84 (described below) of the drive unit 38 (see FIG. 6). The drive sprocket 44 is located closer to the second end (in this embodiment, the right end) 82b of the crank shaft 50 and is connected to the output shaft 84. The rear wheel 36 has a rear sprocket (not shown). The drive sprocket 44 and the rear sprocket are connected via a chain (not shown).

[0030] A control unit consisting of a CPU and an inverter device (neither of which are shown) are provided near the bottom bracket 14, and a battery 46 is attached to the seat post 18. Based on instructions from the control unit, the inverter device converts DC power from the battery 46 into AC power and supplies it to a motor 52 (described below). The motor 52 generates driving force according to the input AC power. The driving force is transmitted to the drive sprocket 44 via a reduction mechanism 56 (described below) and an output shaft 84.

[0031] When a pedaling force is input from the pedals 42, the drive unit 38 uses the motor 52 to generate an auxiliary drive output corresponding to the pedaling force, thereby supplementing the pedaling force. The drive sprocket 44 rotates in conjunction with the rotation of the crank arms 40, and receives the output from the motor 52. That is, the drive unit 38 transmits the pedaling force from the pedals 42 and crank arms 40 and the output from the motor 52 to the drive sprocket 44. The power transmitted to the drive sprocket 44 is then transmitted to the rear wheel 36 via a chain.

[0032] 2 to 6, the drive unit 38 includes a housing 48, a crankshaft 50, a motor 52, a plate-like member 54, and a reduction mechanism 56.

[0033] The housing 48 has a two-piece structure (in this embodiment, a left-right two-piece structure) and includes a first case 58 and a second case 60. The first case 58 and the second case 60 each have a first wall portion 62 and a second wall portion 64. When the first case 58 and the second case 60 are fitted together, the first wall portion 62 and the second wall portion 64 face each other.

[0034] 7, the first wall portion 62 includes inner walls 66, 68. The plate-like member 54 is attached to the inner walls 66, 68. The first case 58 is divided by the inner wall 66 into a space S1 on the crankshaft 50 side and a space S2 on the motor 52 side. A through hole 70 through which the crankshaft 50 passes is provided on the space S1 side of the first wall portion 62, and a bearing support portion 72 for the motor 52 is provided on the inner surface of the first wall portion 62 on the space S2 side, approximately in the center of the space S2.

[0035] The second wall portion 64 is provided with a through hole 74 through which the crankshaft 50 passes, and a bearing support portion 76 for the motor 52 is provided on the inner surface of the second wall portion. The through hole 74 is provided at a position corresponding to the through hole 70, and the bearing support portion 76 is provided to face the bearing support portion 72. The second wall portion 64 is provided with bearing supports 78, 80 for the reduction mechanism 56 between the through hole 74 and the bearing support portion 76.

[0036] The crankshaft 50 has a first end 82a and a second end 82b opposite the first end 82a and on the side where the drive sprocket 44 is located. The crankshaft 50 passes through the through holes 70, 74 so that the first end 82a and the second end 82b protrude from the housing 48, i.e., the first case 58 and the second case 60. In other words, the crankshaft 50 passes through the first wall portion 62 and the second wall portion 64.

[0037] An output shaft 84 is fitted onto the outer periphery of the crankshaft 50. The output shaft 84 includes a connecting shaft 86 and a one-way clutch 88. The connecting shaft 86 is formed in a cylindrical shape, connected to the crankshaft 50 by spline fitting, and rotatable together with the crankshaft 50. The one-way clutch 88 includes an outer member 90 and an inner member 92 provided within the outer member 90. A bearing 94 is interposed between the crankshaft 50 and the through-hole 70. The outer member 90 is connected to the connecting shaft 86 via the inner member 92, a bearing 96 is interposed between the outer member 90 and the crankshaft 50, and a bearing 98 is interposed between the outer member 90 and the through-hole 74. Therefore, the crankshaft 50 is rotatably supported by the housing 48. The outer member 90 is rotatable relative to the housing 48 and the crankshaft 50. The forward rotation of the crankshaft 50 is transmitted to the one-way clutch 88 via the connecting shaft 86, causing the outer member 90 to rotate forward. On the other hand, due to the action of the one-way clutch 88, even if the outer member 90 rotates forward, the rotation is not transmitted to the crankshaft 50. In addition, the outer member 90 has a gear 100.

[0038] 8, a torque sensor 102 is provided within the housing 48 around the connecting shaft 86, i.e., in the vicinity of the crankshaft 50. The torque sensor 102 has a generally C-shaped outer shape with a recess 104. The torque sensor 102 is supported by the first case 58. The torque sensor 102 can detect the torque transmitted to the crankshaft 50 and ultimately to the connecting shaft 86 when the pedals 42 are pedaled. In other words, the torque sensor 102 can detect the torque generated in the crankshaft 50 when the pedals 42 are pedaled.

[0039] The motor 52 includes a stator 106, a rotor 108, and a rotor shaft 110, and is provided within the housing 48. The motor 52 is located on the first end 82a side (on the left side in this embodiment) when viewed from a direction perpendicular to the axial direction of the crankshaft 50. The stator 106 is formed in a substantially hollow cylindrical shape, is provided in the space S2 of the first case 58, and is fixed within the first case 58. The rotor shaft 110 is rotatably supported by the first case 58, the second case 60, and the plate-like member 54. That is, one end of the rotor shaft 110 is supported by the first wall portion 62 via a bearing 112 fitted in the bearing support portion 72, the other end of the rotor shaft 110 is supported by the second wall portion 64 via a bearing 114 fitted in the bearing support portion 76, and an approximately central portion of the rotor shaft 110 is supported by the plate-like member 54 via a bearing 116, thereby rotatably providing the rotor shaft 110 within the housing 48. The rotor 108 is fitted onto the outer periphery of the rotor shaft 110 so that the outer periphery of the rotor 108 faces the inner periphery of the stator 106, and is fixed to the rotor shaft 110 so as to be rotatable together with the rotor shaft 110. The rotor shaft 110 also has an output gear 118.

[0040] 9, plate-like member 54 is provided within housing 48 and fixed to a first case 58 of housing 48 so as to cover at least a portion of motor 52. Plate-like member 54 is made of, for example, metal, has a generally scoop-like shape, and is provided so as to extend in the front-to-rear direction. Therefore, when viewed in the axial direction of crankshaft 50, portions of motor 52 located on both sides of plate-like member 54 (in this embodiment, the upper and lower sides) are not covered by plate-like member 54.

[0041] 10 to 12, the plate-shaped member 54 has a through hole 120, through which the rotor shaft 110 is inserted, approximately near the center. The plate-shaped member 54 includes a narrow portion 122 formed on one side (the front side in this embodiment) of the through hole 120, and a wide portion 124 formed on the other side (the rear side in this embodiment) of the through hole 120. Bearing supports 126 and 128 for the reduction mechanism 56 are provided on a main surface of the wide portion 124 that faces the second wall portion 64. The bearing supports 126 and 128 face the bearing supports 78 and 80 of the second wall portion 64, respectively. The bearing support 126 is provided coaxially with a rotational axis X1 of a first reducer 150 (described below), and the bearing support 128 is provided coaxially with a rotational axis X2 of a second reducer 152 (described below) (see FIG. 6).

[0042] Furthermore, the plate-like member 54 (wide portion 124) has a protruding portion 130 that protrudes outward from the motor 52 when viewed in the axial direction of the crankshaft 50 (see FIG. 9 ). The protruding portion 130 protrudes beyond the contour of the stator 106. In this embodiment, the protruding portion 130 is formed at an end of the wide portion 124. A flat portion 132 having substantially the same shape as the contact surface of the inner wall 66 is formed on the main surface of the protruding portion 130 that faces the first wall portion 62, in order to come into surface contact with the inner wall 66 of the first wall portion 62. A flat portion 134 is formed on the main surface of the end of the narrow portion 122 that faces the first wall portion 62, in order to come into surface contact with the inner wall 68 of the first wall portion 62. This allows the plate-like member 54 to come into contact with the inner walls 66, 68 over a wider area, allowing it to be supported by the housing 48.

[0043] The protruding portion 130 has a through hole 136. The through hole 136 is formed in the center of the bearing support portion 126 and is formed approximately in the center of the flat portion 132.

[0044] Furthermore, the protruding portion 130 has an unsupported portion 138 at its end (the rear end in this embodiment) that is not supported by the housing 48. That is, the unsupported portion 138 is formed at the end of the protruding portion 130 where the flat portion 132 is not formed, and is provided outside the through-hole 136. The unsupported portion 138 has a first recess 140 facing the first wall portion 62.

[0045] 6 and 7 , the first wall portion 62 has a second recess 142 at a position facing the first recess 140, and the inner wall 66 of the first wall portion 62 has a third recess 144 and a fourth recess 146. A rib 147 protruding inward from the first wall portion 62 is formed between the through hole 70 and the inner wall 66, thereby forming the second recess 142 between the rib 147 and the inner wall 66. The third recess 144 is provided at a position corresponding to the through hole 136. The fourth recess 146 is formed by recessing the surface of the inner wall 66 facing the crankshaft 50 (in this embodiment, the rear surface) toward the through hole 136. When the plate-like member 54 is attached to the first wall portion 62, a knock pin 148 is inserted into the through hole 136 and the third recess 144.

[0046] A wiring space S is provided between the non-support portion 138 and the first wall portion 62. When viewed in the axial direction of the crankshaft 50, the wiring space S overlaps with a line segment L that connects the axis P of the crankshaft 50 and the rotation axis X1 of the first reducer 150 (see FIG. 7).

[0047] The speed reduction mechanism 56 is provided within the housing 48 between the plate-like member 54 and the second wall portion 64. The speed reduction mechanism 56 is also provided within the housing 48 between the crankshaft 50 and the rotor shaft 110. The speed reduction mechanism 56 reduces the speed of the rotation generated by the motor 52 and increases the output torque of the motor 52.

[0048] The reduction mechanism 56 includes a first reduction gear 150 and a second reduction gear 152 .

[0049] 6 and 9 , the first reducer 150 is rotatably supported by the plate-like member 54 and the second wall portion 64 such that the rotation axis X1 of the first reducer 150 is located at the protruding portion 130 when viewed in the axial direction of the crankshaft 50. The first reducer 150 includes a rotating shaft 154, a large-diameter gear 156, and a small-diameter gear 158. One end of the rotating shaft 154 is supported by the plate-like member 54 via a bearing 160 fitted in the bearing support portion 126, and the other end of the rotating shaft 154 is supported by the second wall portion 64 via a bearing 162 fitted in the bearing support portion 78, thereby rotatably providing the rotating shaft 154 within the housing 48.

[0050] The second reducer 152 is disposed between the rotor shaft 110 and the first reducer 150, and is rotatably supported by the plate-like member 54 and the second wall portion 64. The second reducer 152 includes a rotating shaft 164, a small-diameter gear 166, a large-diameter gear 168, and a one-way clutch 170. One end of the rotating shaft 164 is supported by the plate-like member 54 via a bearing 172 fitted in the bearing support portion 128, and the other end of the rotating shaft 164 is supported by the second wall portion 64 via a bearing 174 fitted in the bearing support portion 80, thereby rotatably providing the rotating shaft 164 within the housing 48. The one-way clutch 170 is interposed between the rotating shaft 164 and the gear 168. As a result, the forward rotation of the rotor shaft 110 is transmitted to the rotating shaft 164 of the second reducer 152, but the forward rotation of the rotating shaft 164 is not transmitted to the rotor shaft 110.

[0051] 14, gear 168 meshes with output gear 118 on rotor shaft 110, gear 166 meshes with gear 156, and gear 158 meshes with gear 100 on outer member 90 of one-way clutch 88.

[0052] The first reducer 150 and the second reducer 152 reduce the speed of the rotation generated by the motor 52 and increase the output torque of the motor 52 before transmitting it to the outer member 90 of the output shaft 84.

[0053] 6, 13, and 14, a circuit board 176 is provided between the plate-like member 54 and the second wall portion 64 within the housing 48. The circuit board 176 is formed in a generally bifurcated shape so as to avoid the motor 52, the first reducer 150, and the second reducer 152. Referring further to FIG. 9, the circuit board 176 is attached to a plurality of bosses 178a, 178b, and 178c of the first wall portion 62 with fastening members 180. A wire guide 182 is disposed between the first case 58 and the torque sensor 102. Wires 184 drawn from the circuit board 176 are guided between the wire guide 182 and the first case 58 through the routing space S. That is, the wiring 184 drawn out from the circuit board 176 passes between the plate-like member 54 and the first wall portion 62 and between the crankshaft 50 and the rotating shaft 154 of the first reducer 150 as seen in the axial direction of the crankshaft 50, and is then guided between the wire guide 182 and the first wall portion 62. In this manner, the wiring 184 passes between the crankshaft 50 and the rotating shaft 154 of the first reducer 150, which is the reducer closest to the crankshaft 50 as seen in the axial direction of the crankshaft 50. Note that in this embodiment, the wiring 186 from the torque sensor 102 is connected to the circuit board 176 via a route that does not pass through the routing space S. In addition, a heat dissipation sheet 188 is attached to the circuit board 176.

[0054] In this embodiment, the crankshaft 50 corresponds to the input shaft.

[0055] In an electrically assisted bicycle 10 having such a drive unit 38, the plate-shaped member 54, which covers at least a portion of the motor 52, is fixed to the housing 48, so that the plate-shaped member 54 functions as a reinforcing member for the housing 48 and substantially improves the rigidity of the housing 48. Furthermore, the first reducer 150 is rotatably supported by the plate-shaped member 54 and the second wall portion 64 so that the rotation axis X1 of the first reducer 150 is located in the protruding portion 130 that does not cover the motor 52 when viewed in the axial direction of the crankshaft 50. Therefore, the rotation axis X1 of the first reducer 150 can be relatively far from the rotation axis X3 of the motor 52, improving the degree of freedom in the layout of the reduction mechanism 56. In this way, the plate-shaped member 54 can be used effectively.

[0056] By utilizing the unsupported portion 138 of the protruding portion 130, it is possible to easily provide a wiring space S between the unsupported portion 138 and the first wall portion 62. By passing the wiring 184 through the wiring space S, it is possible to keep the wiring 184 away from the gears 156, 158 of the first reducer 150, the gear 100 of the outer member 90, and the like. Therefore, without providing a new separate member, the plate-like member 54 can prevent the wiring 184 from floating and coming into contact with or becoming entangled in the gears 100, 156, 158, and the like.

[0057] The bent portion of the wiring 184, the coupler, etc. can be accommodated in the first recess 140 of the non-supporting portion 138.

[0058] A wide wiring space S can be formed by the first recess 140 and the second recess 142 facing each other.

[0059] When viewed in the axial direction of the crankshaft 50, the wiring space S overlaps with a line segment L connecting the axis P of the crankshaft 50 and the rotation axis X1 of the first reducer 150. By passing the wiring 184 through such wiring space S, it is possible to route the wiring over the shortest distance.

[0060] At least a portion of the bearing support portion 126 is located in the protruding portion 130 of the plate-shaped member 54, and the bearing support portion 126 can support a bearing 160 for rotatably supporting the first reducer 150.

[0061] By inserting the knock pin 148 into the through hole 136 of the protruding portion 130 and the third recess 144 of the first wall portion 62, it is possible to contribute to fixing the plate-like member 54 to the housing 48.

[0062] The plate-like member 54 and the second wall portion 64 can rotatably support the first reducer 150 and the second reducer 152, that is, a plurality of reducers.

[0063] The plate-like member 54 functions as a guide for the wiring 184, so the size of the wire guide 182 can be reduced.

[0064] This invention is suitable for a case where the motor 52 and the drive sprocket 44 are located on opposite sides of the crankshaft 50 in the axial direction, as in the drive unit 38 .

[0065] The drive unit 38 according to the present invention can be suitably used in the power-assisted bicycle 10.

[0066] The plate-like member may be configured as shown in FIG.

[0067] 15 has a protruding portion 130a that is formed by extending the protruding portion 130 of the plate-shaped member 54 further toward the torque sensor 102. The protruding portion 130a has an engaging portion 190 that can engage with the recess 104 of the torque sensor 102. In other words, the protruding portion 130a is formed to be able to come into contact with the torque sensor 102 in order to function as a rotation stopper for the torque sensor 102.

[0068] In this case, a rotation stopper for the torque sensor 102 can be easily configured simply by expanding the protruding portion 130a so that it can come into contact with the torque sensor 102, and the protruding portion 130a can smoothly restrict the rotation of the torque sensor 102. Furthermore, there is a high degree of freedom in the height of the protruding portion 130a in the axial direction of the crankshaft 50, improving the degree of freedom in design.

[0069] The plate-like member and the torque sensor may also be configured as shown in FIG.

[0070] The torque sensor 102a shown in Fig. 16 has a wall 192 facing the plate-shaped member 54b. The plate-shaped member 54b has a protruding portion 130b that extends from the protruding portion 130 of the plate-shaped member 54 toward the torque sensor 102a, and the protruding portion 130b has a protruding portion 194 that can be fixed to the wall 192. By fixing the protruding portion 194 to the wall 192, the protruding portion 130b functions as a rotation stopper for the torque sensor 102a. In this case, the same effect as when the plate-shaped member 54a shown in Fig. 15 is used can be obtained.

[0071] Furthermore, the plate-like member and the circuit board may be configured as shown in FIG.

[0072] In the embodiment shown in FIG. 17, plate-shaped member 54c is formed by further widening plate-shaped member 54. More specifically, protruding portion 130c of plate-shaped member 54c is formed by further widening protruding portion 130 of plate-shaped member 54. Furthermore, circuit board 176a is formed by further widening circuit board 176. This allows the overlapping area of ​​plate-shaped member 54c (protruding portion 130c) and circuit board 176a to be increased, and plate-shaped member 54c (protruding portion 130c) and circuit board 176a are fastened by fastening member 180 to the overlapping area. Therefore, circuit board 176a is fixed to at least protruding portion 130c, and in this embodiment, is fixed to protruding portion 130c and first case 58 of housing 48.

[0073] In this case, the circuit board 176a can be fixed to the protruding portion 130c by utilizing the empty space in the housing 48, and the plate-like member 54c can be used to fix the board. This also allows for grounding. Furthermore, by using the plate-like member 54c to fix the board, it is not necessary to provide a boss for fixing the board on the housing. In this embodiment, the boss 178a (see FIG. 9) on the housing 48 does not need to be provided. In this case, the space for wiring can be increased, and the housing can be made smaller.

[0074] The plate-like member and the circuit board may also be configured as shown in FIG.

[0075] In the embodiment shown in FIG. 18 , plate-shaped member 54d is formed by further widening plate-shaped member 54. More specifically, protruding portion 130d of plate-shaped member 54d is formed by further widening protruding portion 130 of plate-shaped member 54. Furthermore, circuit board 176b is formed by further widening circuit board 176. This increases the overlapping area between plate-shaped member 54d (protruding portion 130d) and circuit board 176b, and plate-shaped member 54d (protruding portion 130d) and circuit board 176b are connected to each other via heat conductive member 196 in a heat-conductive manner within the overlapping area. Therefore, heat generated in circuit board 176b can be dissipated from plate-shaped member 54d via heat conductive member 196.

[0076] In this case, circuit board 176b can be thermally conductively connected to protruding portion 130d by utilizing the empty space within housing 48, allowing plate-like member 54d to function as a heat dissipation portion. Therefore, it is not necessary to provide a heat dissipation member (such as heat dissipation sheet 188 shown in FIG. 14) on circuit board 176b, or the heat dissipation member provided on circuit board 176b can be made smaller. As a result, the degree of freedom in arranging electronic components can be improved, and the housing can also be made smaller.

[0077] Also, a spring part may be used in place of the heat conducting member 196 to function as an earth connection part for noise reduction.

[0078] In the above embodiment, the reduction mechanism 56 includes the first reducer 150 and the second reducer 152, but the present invention is not limited to this. The reduction mechanism may include only the first reducer, and the driving force from the motor may be reduced by the first reducer before being transmitted to the output shaft.

[0079] This invention can also be applied to a drive unit in which a motor is housed in a motor housing. In this case, the first case may have a motor housing that houses a stator of the motor, and the motor housing may be configured as a separate member from the other parts of the first case. In this case, the first wall portion is formed to extend from the motor housing to the other parts.

[0080] The circuit board may also be fixed only to the plate-like member within the housing. [Explanation of symbols]

[0081] 10 Electrically assisted bicycles 38 Drive Unit 44 drive sprocket 48 Housing 50 crankshaft 52 Motor 54, 54a, 54b, 54c, 54d Plate-shaped members 56 Reduction mechanism 62 1st wall section 64 2nd wall 72,76,78,80,126,128 Bearing support part 70, 74, 120, 136 Through holes 82a First end 82b Second end 84 Output shaft 94,96,98,112,114,116,160,162,172,174 Bearings 102,102a Torque sensor 130, 130a, 130b, 130c, 130d protruding parts 138 Non-supporting part 140 First recess 142 Second recess 144 Third Recess 146 4th Recess 148 Knock pin 150 1st reducer 152 2nd reducer 176, 176a, 176b Circuit board 180 Fastening members 184,186 Wiring 196 Thermal Conduction Materials L: A line segment connecting the center of the crankshaft and the rotational axis of the first reducer P axis center S routing space X1,X2,X3 Rotation axis

Claims

1. a housing having a first wall portion and a second wall portion facing the first wall portion; an input shaft that passes through the first wall portion and the second wall portion and is rotatably supported by the housing; a motor provided within the housing; a plate-like member provided within the housing and fixed to the housing so as to cover at least a portion of the motor; a speed reduction mechanism provided in the housing between the plate-like member and the second wall portion to reduce the speed of rotation generated by the motor, the plate-shaped member has a protruding portion that protrudes outward from the motor when viewed in the axial direction of the input shaft, The reduction mechanism includes a first reducer rotatably supported by the plate-shaped member and the second wall portion so that the rotation axis is located in the protruding portion when viewed in the axial direction of the input shaft.

2. the protruding portion has an unsupported portion that is not supported by the housing, The drive unit according to claim 1 , further comprising a wiring space provided between the non-supporting portion and the first wall portion.

3. The drive unit according to claim 2 , wherein the non-supporting portion has a first recess facing the first wall portion.

4. The drive unit according to claim 3 , wherein the first wall portion has a second recess portion facing the first recess portion.

5. The drive unit according to claim 2 , wherein the wiring space overlaps with a line segment connecting an axis of the input shaft and a rotation axis of the first reducer when viewed in the axial direction of the input shaft.

6. a torque sensor provided in the housing near the input shaft for detecting torque transmitted to the input shaft; The drive unit according to claim 1 , wherein the protruding portion is provided so as to be able to come into contact with the torque sensor in order to function as a rotation stopper for the torque sensor.

7. The drive unit according to claim 1 , further comprising a circuit board provided in the housing between the plate-like member and the second wall portion and fixed to at least the protruding portion.

8. The drive unit according to claim 1 , further comprising a circuit board provided in the housing between the plate-like member and the second wall portion and connected to the protruding portion in a thermally conductive manner.

9. the plate-like member has a bearing support portion provided coaxially with the rotation axis of the first reducer, The drive unit according to claim 1 , further comprising a bearing interposed between the first reducer and the bearing support.

10. The protruding portion has a through hole, the first wall portion has a third recess at a position corresponding to the through hole, The drive unit according to claim 1 , further comprising a knock pin inserted into the through hole and the third recess.

11. 2. The drive unit according to claim 1, wherein the reduction mechanism further includes a second reducer rotatably supported by the plate-like member and the second wall portion to reduce the rotation generated by the motor and transmit the reduced rotation to the first reducer.

12. The input shaft has a first end and a second end opposite the first end and on which a drive sprocket is located, The drive unit according to claim 1 , wherein the motor is located on the first end side when viewed from a direction perpendicular to the axial direction of the input shaft.

13. An electrically assisted bicycle comprising the drive unit according to claim 1.

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