JP2014196080A - Drive unit and electric assist bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a drive unit in an axial direction of a crank shaft at the drive unit used in an electric assist bicycle.SOLUTION: A drive unit 50 is used in an electric assist bicycle. The drive unit 50 includes: a motor 60; a first transmission gear 84; and a driven gear 104. A member, which has the largest diameter when viewed from an axial direction of a crank shaft 54 from among the motor 60, the first transmission gear 84, and the driven gear 104, is referred to as a first member 104. A member, which has the second largest diameter, is referred to as a second member 60. A substrate 150 is disposed between the first member 104 and the second member 60 in the axial direction of the crank shaft 54.

Description

  The present invention relates to a drive unit used for a battery-assisted bicycle and a battery-assisted bicycle including the drive unit.

  In recent years, a battery-assisted bicycle has been proposed that assists a driver's pedaling force (hereinafter referred to as a pedaling force) with the driving force of a motor. The battery-assisted bicycle includes a drive unit for assisting the pedal effort. The drive unit is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-114851.

  In the above publication, the drive unit includes a rotating member. The rotating member is rotatably provided on the same axis as the pedal crankshaft. The rotating member connects the human power drive system and the motor drive system. A motor is disposed behind the vehicle body relative to the rotating member. The motor and the rotating member are connected via a gear reducer.

JP 2008-114851 A JP 2003-219603 A

  Although not specified in the above publication, a circuit board is disposed in the drive unit. As described in Japanese Patent Application Laid-Open No. 2003-219603, the circuit board is generally arranged away from a path (driving force transmission path) through which the driving force of the motor is transmitted.

  When such a circuit board arrangement method is applied to the drive unit described in Japanese Patent Application Laid-Open No. 2008-114851, the circuit board is arranged away from the motor, the gear reducer, and the rotating member. Therefore, it becomes difficult to reduce the size of the drive unit when viewed from the axial direction of the pedal crankshaft and the size of the drive unit in the axial direction of the pedal crankshaft.

  An object of the present invention is to reduce the size of the crankshaft in the axial direction in a drive unit used in a battery-assisted bicycle.

  Another object of the present invention is to provide a battery-assisted bicycle including the drive unit.

Means for Solving the Problems and Effects of the Invention

  The drive unit of the present invention is used for a battery-assisted bicycle and includes a crankshaft, a motor, a transmission shaft, and a substrate.

  The transmission shaft extends parallel to the central axis of the crankshaft. The substrate has a mounting surface that extends in a direction perpendicular to the central axis of the crankshaft.

  The motor includes a rotor, an output shaft, and an output gear. The output shaft rotates with the rotor and extends parallel to the central axis of the crankshaft. The output gear is disposed on the output shaft.

  The drive unit further includes a first transmission gear, a second transmission gear, and a driven gear. The first transmission gear is disposed on the transmission shaft, meshes with the output gear, and has more teeth than the output gear. The second transmission gear is disposed on the transmission shaft. The driven gear is disposed on the crankshaft, meshes with the second transmission gear, and has more teeth than the second transmission gear.

  Of the motor, the first transmission gear, and the driven gear, the member having the largest diameter when viewed from the axial direction of the crankshaft is defined as the first member, and the member having the next largest diameter is defined as the second member. In this case, the substrate is disposed between the first member and the second member in the axial direction of the crankshaft.

  According to the drive unit of the present invention, the size of the drive unit in the axial direction of the crankshaft can be reduced.

It is a right view which shows schematic structure of the battery-assisted bicycle by embodiment of this invention. It is a longitudinal cross-sectional view which shows schematic structure of a drive unit. It is a right view which shows the drive unit of the state which removed the 2nd housing part. It is sectional drawing which shows the positional relationship of an output shaft, a rotor, and a bearing. It is a longitudinal cross-sectional view which expands and shows a part of FIG. It is a right view which shows the positional relationship of the rotation center of a crankshaft, the rotation center of an output shaft, and the rotation center of a transmission shaft. It is a longitudinal cross-sectional view which expands and shows a part of FIG. It is a right view for demonstrating a board | substrate. It is a right view for demonstrating a 1st area | region. It is a longitudinal cross-sectional view for demonstrating the relationship between a 1st area | region and a 2nd housing part. It is a right view for demonstrating a 2nd area | region and a 3rd area | region. It is a perspective view which shows a partition wall. It is a perspective view which shows a partition wall, Comprising: It is a perspective view which shows the partition wall seen from the direction different from FIG. FIG. 4 is a right side view showing a state where a driven gear is removed from the drive unit shown in FIG. 3.

  Hereinafter, a drive unit and a battery-assisted bicycle according to embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description of the members will not be repeated. Moreover, the dimension of the structural member in each figure does not faithfully represent the actual dimension of the structural member, the dimensional ratio of each structural member, or the like. In the following description, front, rear, left, and right mean front, rear, left, and right as viewed from the driver who is seated on the saddle 18 and holds the handle 16.

[Overall configuration of battery-assisted bicycle]
A battery-assisted bicycle 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a right side view showing a schematic configuration of the battery-assisted bicycle 10.

  The battery-assisted bicycle 10 includes a body frame 12, a front wheel 14F, a rear wheel 14R, a handle 16, a saddle 18, and a drive unit 50.

  The vehicle body frame 12 includes a head pipe 12A, a main frame 12B, a down frame 12C, a seat frame 12D, a pair of chain stays 12E and 12E, a pair of seat stays 12F and 12F, and a bracket 12G.

  The head pipe 12A is disposed at the front portion of the battery-assisted bicycle 10 and extends in the vertical direction. A stem 20 is rotatably inserted into the head pipe 12A. A handle 16 is fixed to the upper end of the stem 20. A front fork 22 is fixed to the lower end of the stem 20. A front wheel 14F is rotatably attached to the lower end of the front fork 22.

  The main frame 12B is disposed behind the head pipe 12A and extends in the front-rear direction. The front end of the main frame 12B is connected to the upper end of the head pipe 12A. The rear end of the main frame 12B is connected to the upper end of a seat frame 12D that extends in the vertical direction.

  The down frame 12C is disposed behind the head pipe 12A and extends in the front-rear direction. The down frame 12C is disposed below the main frame 12B. The front end of the down frame 12C is connected to the head pipe 12A. The rear end of the down frame 12C is connected to the lower end of the seat frame 12D.

  A seat pipe 24 is inserted into the seat frame 12D. A saddle 18 is attached to the upper end of the seat pipe 24.

  The pair of chain stays 12E and 12E extend in the front-rear direction. A rear wheel 14R is disposed between the pair of chain stays 12E and 12E. The front end of each chain stay 12E is connected to the lower end of the seat frame 12D. A rear wheel 14R is rotatably attached at the rear end of each chain stay 12E. A driven sprocket 26 is disposed on the right side of the rear wheel 14R. The driven sprocket 26 is connected to the rear wheel 14R via a one-way clutch (not shown).

  The pair of seat stays 12F, 12F extend in the front-rear direction. The front end of each seat stay 12F is connected to the upper end of the seat frame 12D. The rear end of the seat stay 12F disposed on the right side of the rear wheel 14R is connected to the rear end of the chain stay 12E disposed on the right side of the rear wheel 14R. The rear end of the seat stay 12F disposed on the left side of the rear wheel 14R is connected to the rear end of the chain stay 12E disposed on the left side of the rear wheel 14R.

  A carrier 28 is disposed behind the saddle 18. The carrier 28 is attached to the pair of seat stays 12F and 12F. A battery unit 30 is disposed on the carrier 28. The battery unit 30 supplies power to the motor 60 (see FIG. 2) of the drive unit 50. The battery unit 30 includes a battery and a control unit. The battery is a chargeable / dischargeable rechargeable battery. The control unit controls the charging / discharging of the battery, and monitors the output current and the remaining amount of the battery.

  The bracket 12G covers the rear end of the down frame 12C, the lower end of the seat frame 12D, and the front end of each chain stay 12E. The drive unit 50 is fixed to the bracket 12G by a plurality of fasteners (not shown). Details of the drive unit 50 will be described later.

  An endless chain 32 is wound around the drive sprocket 58 and the driven sprocket 26 provided in the drive unit 50.

  One end of the crank arm 34R is attached to one axial end of the crankshaft 54 included in the drive unit 50, and one end of the crank arm 34L is attached to the other axial end. A pedal 36R is attached to the other end of the crank arm 34R, and a pedal 36L is attached to the other end of the crank arm 34L.

[Drive unit]
The drive unit 50 will be described with reference to FIG. FIG. 2 is a longitudinal sectional view showing a schematic configuration of the drive unit 50.

  The drive unit 50 includes a housing 52, a crankshaft 54, a rotation member 56, a drive sprocket 58, a motor 60 and a speed reduction mechanism 62.

[housing]
The housing 52 includes a first housing part 52L and a second housing part 52R. The first housing part 52L and the second housing part 52R are each made of a metal material. The metal material is, for example, an aluminum alloy. The first housing portion 52L and the second housing portion 52R are assembled from the left and right directions and are fixed to each other by a plurality of fastening fittings 66. The housing 52 is attached to the bracket 12G by a plurality of fasteners (not shown).

  The housing 52 will be described in a little more detail. The first housing portion 52A has an overlapping surface 53A. The second housing part 52B has an overlapping surface 53B. The overlapping surface 53A and the overlapping surface 53B are surfaces perpendicular to the axial direction of the crankshaft 54, respectively. In a state where the first housing portion 52A and the second housing portion 52B are assembled, the overlapping surface 53A and the overlapping surface 53B are overlapped. That is, the first housing portion 52A and the second housing portion 52B are overlapped in the axial direction of the crankshaft 54.

[Crankshaft]
The crankshaft 54 is disposed so as to penetrate the housing 52 in the left-right direction. That is, the center axis L1 of the crankshaft 54 extends in the left-right direction. The center axis L1 coincides with the rotation center C1 of the crankshaft 54 when viewed from the axial direction of the crankshaft 54.

  The crankshaft 54 is supported by two bearings 68L and 68R so as to be rotatable around the central axis L1 of the crankshaft 54. The bearing 68L is disposed on one end side (left end side) in the axial direction of the crankshaft 54 with respect to the rotating member 56, and is fixed to the first housing portion 52L. The bearing 68R is disposed on the other axial end side (right end side) of the crankshaft 54 with respect to the bearing 68L, and is fixed to the second housing portion 52R.

  The crankshaft 54 is disposed through the rotating member 56. The drive sprocket 58 is disposed outside the housing 52 and on the right side of the housing 52, and rotates together with the rotating member 56. Details of the rotating member 56 will be described later.

[motor]
The motor 60 is disposed in the housing 52. The motor 60 generates a driving force for assisting the traveling of the battery-assisted bicycle 10 based on a control signal output from a control device (not shown). The motor 60 includes a stator 70, a rotor 72, an output shaft 74, and an output gear 76.

  The stator 70 includes a plurality (14 in this embodiment) of bobbins 70B around which coils 70A are wound. An iron core 70C is inserted into each bobbin 70B. The stator 70 is fixed to the first housing portion 52L. A cover 77 that covers the motor 60 from the left side is attached to the first housing portion 52L.

  The rotor 72 is disposed inside the stator 70. The rotor 72 is a permanent magnet in which N poles and S poles are alternately magnetized in the circumferential direction. In the present embodiment, the number of N poles and S poles is 7 respectively.

  The output shaft 74 is disposed through the rotor 72 and is fixed to the rotor 72. That is, the output shaft 74 rotates with the rotor 72.

  The output shaft 74 is made of a metal material. The metal material is, for example, iron.

  The center axis L2 of the output shaft 74 is parallel to the center axis L1 of the crankshaft 54. That is, the output shaft 74 extends in parallel to the central axis L1 of the crankshaft 54. Note that the center axis L2 coincides with the rotation center C2 of the output shaft 74 when viewed from the axial direction of the output shaft 74, that is, the axial direction of the crankshaft 54.

  The output shaft 74 is supported by the two bearings 78L and 78R so as to be rotatable around the central axis L2. In other words, the output shaft 74 is supported by the pair of bearings 78L and 78R so as to be rotatable around the central axis L2. The bearing 78 </ b> L is disposed on one axial end side (left end side) of the rotor 72 and is fixed to the cover 77. The bearing 78R is disposed on the other axial end side (right end side) of the rotor 72 and is fixed to the second housing portion 52R.

  The bearing 78L is disposed at a position different from the bearing 68L in the axial direction of the crankshaft 54. Here, “the bearing 78L and the bearing 68L are arranged at different positions in the axial direction of the crankshaft 54” means that the bearing 78L is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. This means that it does not overlap the bearing 68L. The bearing 78L is arranged farther from the bearing 68R than the bearing 68L in the axial direction of the crankshaft 54.

  The bearing 78R is disposed at a position different from the bearing 68R in the axial direction of the crankshaft 54. Here, “the bearing 78R and the bearing 68R are arranged at different positions in the axial direction of the crankshaft 54” means that the bearing 78R is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. This means that it does not overlap the bearing 68R. The bearing 78R is disposed between the bearing 68L and the bearing 68R in the axial direction of the crankshaft 54. The bearing 78R is disposed closer to the bearing 68R than the bearing 68L in the axial direction of the crankshaft 54.

  The rotation center C2 of the output shaft 74 will be described with reference to FIGS. FIG. 3 is a right side view showing the drive unit 50 with the second housing portion 52R removed.

  The rotation center C2 is located in front of the rotation center C1 of the crankshaft 54. The rotation center C2 is located above the rotation center C1 (see FIG. 3).

  The output gear 76 will be described with reference to FIG. FIG. 4 is a longitudinal sectional view showing the positional relationship between the output shaft 74, the rotor 72, and the bearings 78L and 78R.

  The output gear 76 is formed on the output shaft 74 on the other axial end side (right end side) of the rotor 72. That is, the output gear 76 is made of a metal material and is disposed on the output shaft 74.

  As shown in FIG. 4, the output gear 76 is formed closer to the bearing 78R than the center C0 of the axial length of the output shaft 74. The center C0 is located closer to the bearing 78R than the rotor 72 is. The bearing 78 </ b> R is arranged farther from the rotor 72 than the output gear 76 in the axial direction of the output shaft 74. That is, the bearing 78 </ b> R is disposed on the opposite side of the rotor 72 with respect to the output gear 76 in the axial direction of the output shaft 74.

[Electrical component]
The electrical component 80 will be described with reference to FIGS. 2 and 5. FIG. 5 is an enlarged longitudinal sectional view showing a part of FIG.

  The electrical component 80 is disposed around the output shaft 74. The electric component 80 is used to drive and control the motor 60. At least a part of the electrical component 80 overlaps the motor 60 when viewed from the axial direction of the crankshaft 54. The electrical component 80 includes a detected portion 80A, a plurality of bus bars 80B, a substrate 80C, a detection element 80D, and a connector 80E.

  The detected portion 80 </ b> A is disposed between the rotor 72 and the output gear 76 in the axial direction of the output shaft 74. The detected portion 80A has a ring shape. An output shaft 74 is inserted into the detected part 80A. The detected portion 80A is arranged coaxially with the output shaft 74. The detected portion 80A is fixed to the output shaft 74. That is, the detected portion 80A rotates with the output shaft 74. 80 A of to-be-detected parts are arrange | positioned inside the stator 70, when it sees from the axial direction of the output shaft 74. As shown in FIG.

  Each of the plurality of bus bars 80B is embedded in a support portion 80F made of an insulating material (for example, synthetic resin). The substrate 80C is supported by the support portion 80F. The support portion 80F is attached to the bobbin 70B. In this state, the detection element 80 </ b> D provided on the substrate 80 </ b> C is disposed to face the detected portion 80 </ b> A in the axial direction of the output shaft 74. The detection element 80D detects the rotation of the detected part 80A by detecting a change in magnetism that occurs with the rotation of the detected part 80A. Using the result, a control device (not shown) controls the rotation of the rotor 72. A connector (not shown) for connecting the board 80C and the control device is connected to the connector 80E provided on the board 80C.

[Deceleration mechanism]
The speed reduction mechanism 62 will be described with reference to FIGS. 2 and 5. The speed reduction mechanism 62 includes a transmission shaft 82, a first transmission gear 84, and a second transmission gear 86.

  The transmission shaft 82 is disposed in the housing 52. The central axis L3 of the transmission shaft 82 is parallel to the central axis L1 of the crankshaft 54. That is, the transmission shaft 82 extends in parallel to the central axis L1 of the crankshaft 54. The center axis L3 coincides with the rotation center C3 of the transmission shaft 82 when viewed from the axial direction of the transmission shaft 82, that is, the axial direction of the crankshaft 54.

  The transmission shaft 82 is supported by two bearings 88L and 88R so as to be rotatable around the central axis L3. The bearing 88L is fixed to the first housing portion 52L. The bearing 88R is fixed to the second housing portion 52R.

  At least a part of the bearing 88 </ b> L overlaps the stator 70 when viewed from the axial direction of the crankshaft 54. The rotation center C3 of the transmission shaft 82 overlaps the stator 70 when viewed from the axial direction of the crankshaft 54. That is, the rotation center C3 of the transmission shaft 82 overlaps the motor 60 when viewed from the axial direction of the crankshaft 54 (see FIG. 3).

  The bearing 88L is disposed at the same position as the electrical component 80 in the axial direction of the crankshaft 54. Here, “the bearing 88L and the electric component 80 are disposed at the same position in the axial direction of the crankshaft 54” means that the bearing 88L is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. That at least a part of is overlapped with the electric component 80.

  The electrical component 80 is not disposed between the bearing 88L and the motor 60 in the axial direction of the crankshaft 54. That is, the bearing 88L and the electric component 80 are arranged at different positions in the circumferential direction around the central axis L2 of the output shaft 74. In other words, when viewed from the axial direction of the crankshaft 54, at least a part of the bearing 88 </ b> L and at least a part of the electrical component 80 overlap the motor 60 in different regions.

  The bearing 88L is disposed at a position different from the bearing 78L in the axial direction of the crankshaft 54. Here, “the bearing 88L and the bearing 78L are arranged at different positions in the axial direction of the crankshaft 54” means that the bearing 88L is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. This means that it does not overlap the bearing 78L. The bearing 88L is disposed closer to the bearing 78R than the bearing 78L in the axial direction of the crankshaft 54.

  The bearing 88R is disposed at a position different from the bearing 78R in the axial direction of the crankshaft 54. Here, “the bearing 88R and the bearing 78R are disposed at different positions in the axial direction of the crankshaft 54” means that the bearing 88R is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. This means that it does not overlap the bearing 78R. The bearing 88R is arranged farther from the bearing 78L than the bearing 78R in the axial direction of the crankshaft 54.

  As shown in FIG. 2, the bearing 88 </ b> L is disposed at a position different from the bearing 68 </ b> L in the axial direction of the crankshaft 54. Here, “the bearing 88L and the bearing 68L are arranged at different positions in the axial direction of the crankshaft 54” means that the bearing 88L is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. This means that it does not overlap the bearing 68L. The bearing 88L is disposed between the bearing 68L and the bearing 68R in the axial direction of the crankshaft 54. The bearing 88L is disposed closer to the bearing 68L than the bearing 68R in the axial direction of the crankshaft 54.

  As shown in FIG. 2, the bearing 88 </ b> R is disposed at the same position as the bearing 68 </ b> R in the axial direction of the crankshaft 54. Here, “the bearing 88R and the bearing 68R are disposed at the same position in the axial direction of the crankshaft 54” means that the bearing 88R is viewed from a direction orthogonal to the central axis L1 of the crankshaft 54. It means that at least a part overlaps the bearing 68R.

  The rotation center C3 of the transmission shaft 82 is located in front of the rotation center C1 of the crankshaft 54 and rearward of the rotation center C2 of the output shaft 74, as shown in FIGS. As shown in FIG. 3, the rotation center C3 is positioned above the rotation center C1 and above the rotation center C2.

  That is, as shown in FIG. 6, the first line segment S1 connecting the rotation center C1 and the rotation center C2, the second line segment S2 connecting the rotation center C2 and the rotation center C3, the rotation center C3, and the rotation center C1. A triangle is formed by the third line segment S3 connecting the two. The first line segment S1 is longer than the second line segment S2 and the third line segment S3.

  The description will be made with reference to FIGS. 2 and 5 again. The first transmission gear 84 is made of synthetic resin. The first transmission gear 84 is disposed on the transmission shaft 82. The first transmission gear 84 is disposed closer to the bearing 88R than the bearing 88L in the axial direction of the transmission shaft 82. The first transmission gear 84 meshes with the output gear 76. As a result, the driving force generated by the motor 60 is transmitted from the output gear 76 to the first transmission gear 84. Here, a one-way clutch 83 is disposed between the first transmission gear 84 and the transmission shaft 82. Accordingly, when the output gear 76 rotates in the forward direction (correct direction), the first transmission gear 84 rotates in the reverse direction, and the output gear 76 rotates in the reverse direction (wrong direction). In this case, the first transmission gear 84 does not rotate. The first transmission gear 84 has a larger diameter than the output gear 76 and has more teeth than the output gear 76. That is, the first transmission gear 84 is decelerated more than the output gear 76.

  The second transmission gear 86 is made of a metal material. The metal material is, for example, iron. The second transmission gear 86 is disposed on the transmission shaft 82. The second transmission gear 86 is disposed at a position different from the first transmission gear 84 in the axial direction of the transmission shaft 82. The second transmission gear 86 is fixed to the transmission shaft 82 by spline fitting. That is, the second transmission gear 86 rotates together with the transmission shaft 82. The second transmission gear 86 is supported by the bearing 88R so as to be rotatable around the central axis L3 of the transmission shaft 82. That is, the second transmission gear 86 is further away from the bearing 88L than the first transmission gear 84.

  The second transmission gear 86 is disposed at the same position as the bearing 78 </ b> R in the axial direction of the crankshaft 54. Here, “the second transmission gear 86 and the bearing 78R are disposed at the same position in the axial direction of the crankshaft 54” means that when viewed from a direction orthogonal to the central axis L1 of the crankshaft 54, It means that at least a part of the second transmission gear 86 overlaps the bearing 78R.

  As shown in FIG. 6, when viewed from the axial direction of the crankshaft 54, the second transmission gear 86 does not overlap the first line segment S1.

[Rotating member]
The rotating member 56 will be described with reference to FIG. FIG. 7 is an enlarged longitudinal sectional view showing a part of FIG.

  The rotating member 56 is disposed coaxially with the crankshaft 54 and rotates together with the crankshaft 54. The rotating member 56 includes a connecting shaft portion 56A, a torque detection device 56B, and a one-way clutch 56C.

  The connecting shaft portion 56A is disposed at one end portion (left end portion) in the axial direction of the rotating member 56 and is located in the housing 52 (see FIG. 2). The connecting shaft portion 56A has a cylindrical shape. The crankshaft 54 is inserted into the connecting shaft portion 56A. The connecting shaft portion 56A is disposed coaxially with the crankshaft 54.

  A serration 92 is formed on the inner peripheral surface of one axial end portion of the connecting shaft portion 56A. The serrations 92 mesh with serrations 54 </ b> A formed on the outer peripheral surface of the crankshaft 54. Thereby, the connecting shaft portion 56A is connected to the crankshaft 54. As a result, the connecting shaft portion 56 </ b> A rotates together with the crankshaft 54 regardless of whether the crankshaft 54 rotates in the forward rotation direction or the reverse rotation direction. A slide bearing 106 is disposed between the other axial end portion of the connecting shaft portion 56A and the crankshaft 54.

  The torque detection device 56B is disposed in the housing 52 (see FIG. 2). The torque detection device 56B detects the torque generated in the crankshaft 54 when the driver pedals the pedals 36R and 36L (see FIG. 1). The torque detection device 56B is a magnetostrictive torque sensor.

  The torque detection device 56B includes a mounting shaft portion 94, a coil 96, a detection element 98, and a shield 100. The attachment shaft portion 94 is attached to the outer peripheral surface of the connection shaft portion 56A and rotates relative to the connection shaft portion 56A. That is, the attachment shaft portion 94 does not rotate with the connecting shaft portion 56A. The coil 96 is disposed on the outer peripheral surface of the mounting shaft portion 94. The detection element 98 detects torque generated in the crankshaft 54 by detecting a voltage change of the coil 96 due to the distortion of the connecting shaft portion 56A. The detection element 98 outputs the detected torque to a control device (not shown). The control device refers to the torque output from the detection element 98, grasps the pedaling state by the driver, and controls the motor 60. The shield 100 prevents the detection accuracy of the detection element 98 from deteriorating due to an external magnetic field. The shield 100 engages with an engagement piece (not shown) formed in the first housing portion 52L. That is, the shield 100 does not rotate with the connecting shaft portion 56A.

  The one-way clutch 56C is disposed coaxially with the crankshaft 54 on the drive sprocket 58 side than the torque detection device 56B. The one-way clutch 56 </ b> C transmits the rotational force that rotates the crankshaft 54 in the forward rotation direction to the drive sprocket 58, and does not transmit the rotational force that rotates the crankshaft 54 in the backward rotation direction to the drive sprocket 58.

  The one-way clutch 56 </ b> C includes a driving member 102 and a driven gear 104. The drive member 102 includes a main body portion 108 and a cylinder portion 110.

  The main body 108 has a ring shape. The crankshaft 54 is inserted into the main body 108. The main body 108 is disposed coaxially with the crankshaft 54.

  A serration 112 is formed on the inner peripheral surface of the main body 108. The serration 112 meshes with a serration 114 formed on the outer peripheral surface of the other axial end portion of the connecting shaft portion 56A. As a result, the main body portion 108, that is, the drive member 102 is connected to the connecting shaft portion 56A. As a result, even if the connecting shaft portion 56A rotates in either the forward rotation direction or the backward rotation direction, the main body portion 108, that is, the drive member 102 rotates together with the connecting shaft portion 56A. In other words, the drive member 102 rotates with the crankshaft 54 regardless of whether the crankshaft 54 rotates in the forward rotation direction or the reverse rotation direction.

  The cylinder part 110 is arranged coaxially with the main body part 108 on the drive sprocket 58 side of the main body part 108. The cylinder part 110 is a cylindrical member and is disposed coaxially with the crankshaft 54. The cylinder part 110 is formed integrally with the main body part 108.

  The driven gear 104 includes a shaft portion 116. The shaft portion 116 has a cylindrical shape. A crankshaft 54 is inserted into the shaft portion 116. The shaft portion 116 is disposed coaxially with the crankshaft 54 and is disposed coaxially with the drive member 102. That is, the driven gear 104 is disposed coaxially with the crankshaft 54 and is disposed coaxially with the driving member 102.

  Sliding bearings 122 and 124 are disposed between the shaft portion 116 and the crankshaft 54. As a result, the driven gear 104 can rotate relative to the crankshaft 54.

  The shaft portion 116 includes a driven shaft portion 117 and a mounting shaft portion 118. The driven shaft portion 117 is disposed closer to the drive member 102 than the mounting shaft portion 118 and is coaxial with the mounting shaft portion 118. The driven shaft portion 117 is formed integrally with the mounting shaft portion 118.

  The driven shaft portion 117 is disposed inside the cylinder portion 110 in a direction orthogonal to the central axis L1 of the crankshaft 54. A ratchet mechanism 120 is disposed between the driven shaft portion 117 and the cylindrical portion 110. As a result, the rotational force in the forward rotation direction of the driving member 102 is transmitted to the driven shaft portion 117, that is, the driven gear 104, while the rotational force in the backward rotation direction of the driving member 102 is driven to the driven shaft portion 117, that is, Is not transmitted to the driven gear 104.

  The attachment shaft portion 118 is supported by the second bearing 68R so as to be rotatable around the central axis of the crankshaft 54. The attachment shaft portion 118 has a portion located on the opposite side of the drive member 102 with respect to the second bearing 68R. A drive sprocket 58 is attached to this portion (see FIG. 2).

  That is, the one-way clutch 56C allows the rotational force that rotates the drive sprocket 58 in the forward rotation direction around the center axis L1 of the crankshaft 54 to be transmitted to the drive sprocket 58, but causes the drive sprocket 58 to move in the reverse rotation direction. The rotational force to be rotated is prevented from being transmitted to the drive sprocket 58.

  The driven gear 104 meshes with the second transmission gear 86. The driven gear 104 is larger in diameter than the second transmission gear 86 and has more teeth than the second transmission gear 86. That is, the driven gear 104 is decelerated more than the second transmission gear 86.

  The driven gear 104 is disposed at the same position as the bearing 78 </ b> R in the axial direction of the crankshaft 54. Here, “the driven gear 104 and the bearing 78R are disposed at the same position in the axial direction of the crankshaft 54” means that the driven gear 104 and the bearing 78R are viewed from a direction perpendicular to the central axis L1 of the crankshaft 54. It means that at least a part of the drive gear 104 overlaps the bearing 78R.

  The driven gear 104 is made of a metal material. The metal material is, for example, iron.

  The relationship among the driven gear 104, the motor 60, and the first transmission gear 84 will be described with reference to FIG.

  When viewed from the axial direction of the crankshaft 54, the driven gear 104 has a larger diameter than the motor 60 and a larger diameter than the first transmission gear 84. The motor 60 has a larger diameter than the first transmission gear 84. That is, among the motor 60, the first transmission gear 84, and the driven gear 104, the member (first member) having the largest diameter when viewed from the axial direction of the crankshaft 54 is the driven gear 104. The member with the next largest diameter (second member) is the motor 60. The member with the smallest diameter (third member) is the first transmission gear.

  At least a part of the driven gear 104 overlaps the motor 60 when viewed from the axial direction of the crankshaft 54. At least a portion of the first transmission gear 84 overlaps a region 126 where the driven gear 104 and the motor 60 overlap when viewed from the axial direction of the crankshaft 54. That is, at least a part of the first transmission gear 84 overlaps each of the driven gear 104 and the motor 60 when viewed from the axial direction of the crankshaft 54.

[Rotation detector]
The rotation detection device 130 will be described with reference to FIG. The rotation detection device 130 is disposed in the housing 52 and detects the rotation of the crankshaft 54. The rotation detection device 130 includes a ring magnet 132 as a detected portion and a detection element 134 that detects the rotation of the ring magnet 132.

  The ring magnet 132 has an annular plate shape. In the ring magnet 132, the end surface in the axial direction becomes a magnetic pole forming surface. That is, in the ring magnet 132, N poles and S poles are alternately formed around the central axis L1 of the crankshaft 54 at the end face in the axial direction.

  The ring magnet 132 is attached to the support member 136. The support member 136 includes a cylindrical portion 138 and an annular portion 140.

  The cylindrical portion 138 extends in the axial direction of the crankshaft 54. The cylinder part 138 is fixed to the outer peripheral surface of the cylinder part 110. Examples of a method for fixing the tube portion 138 to the outer peripheral surface of the tube portion 110 include press-fitting and adhesion.

  The annular portion 140 is disposed coaxially with the cylindrical portion 138 at one axial end of the cylindrical portion 138. The annular portion 140 is formed integrally with the cylindrical portion 138. The annular portion 140 includes a mounting surface 136A. The mounting surface 136A is an end surface in the axial direction of the annular portion 140, and is an annular surface that extends in a direction perpendicular to the central axis L1 of the crankshaft 54.

  The ring magnet 132 is superposed on the annular portion 140 in the axial direction of the crankshaft 54. In this state, the end surface of the ring magnet 132 in the axial direction and the mounting surface 136A are bonded.

  As described above, the tube portion 138 is fixed to the outer peripheral surface of the tube portion 110. That is, the ring magnet 132 rotates together with the rotating member 56.

  The detection element 134 is disposed opposite to the magnetic pole forming surface of the ring magnet 132 in the axial direction of the crankshaft 54. The detection element 134 detects that the ring magnet 132 rotates together with the rotating member 56. In the present embodiment, the detection element 134 detects a change in the magnetic field generated as the ring magnet 132 rotates together with the rotating member 56. That is, in the present embodiment, the rotation detection device 130 is a magnetic rotation detection sensor.

  The ring magnet 132 is provided on the driving member 102 that rotates together with the crankshaft 54 in the rotating member 56. Therefore, the rotation of the crankshaft 54 is detected by detecting the change in the magnetic field generated with the rotation of the ring magnet 132. The detection element 134 outputs the detected rotation of the crankshaft 54 to a control device (not shown). The control device refers to not only the torque detected by the detection element 98 but also the rotation of the crankshaft 54 detected by the detection element 134, grasps the pedaling state by the driver, and controls the motor 60.

  The detection element 134 is a one-chip Hall IC and includes two detection elements. Thereby, the transverse magnetic field and the longitudinal magnetic field of the ring magnet 132 can be detected. As a result, it can be determined whether the ring magnet 132 is rotating in the forward rotation direction or the reverse rotation direction.

[substrate]
The detection element 134 is provided on the substrate 150. The board 150 is a printed wiring board. The substrate 150 is disposed in the housing 52 as shown in FIG. A control device (not shown) that controls the operation of the drive unit 50 is mounted on the substrate 150. The substrate 150 is coated with a waterproof coating material.

  The substrate 150 will be described with reference to FIGS. 2 and 8 to 11. FIG. 8 is a right side view for explaining the substrate 150. In FIG. 8, the hatched portion is the substrate 150. FIG. 9 is a right side view for explaining the first region 154. In FIG. 9, the hatched portion is the first region 154. FIG. 10 is a longitudinal sectional view for explaining the relationship between the first region 154 and the second housing portion 52R. FIG. 11 is a right side view for explaining the second region 162 and the third region 164. In FIG. 11, the hatched portions are the second region 162 and the third region 164.

  As shown in FIG. 2, the substrate 150 has a mounting surface 152. The mounting surface 152 is one end surface in the thickness direction of the substrate 150. Various electrical components for controlling the operation of the drive unit 50 are mounted on the mounting surface 152. The mounting surface 152 extends in a direction orthogonal to the central axis L1 of the crankshaft 54.

  As shown in FIG. 2, the substrate 150 is disposed between the driven gear 104 and the motor 60 in the axial direction of the crankshaft 54. Here, “the substrate 150 is disposed between the driven gear 104 and the motor 60” means that the stator 70 having the largest diameter when viewed from the axial direction of the crankshaft 54 of the motor 60, and the driven It means that the substrate 150 is disposed between the gear 104.

  As shown in FIG. 2, the substrate 150 is disposed along the overlapping surfaces 53L and 53R of the first housing portion 52L and the second housing portion 52R. Here, “the substrate 150 is arranged along the overlapping surfaces 53L and 53R” means that the end surface in the thickness direction of the substrate 150 coincides with the overlapping surfaces 53L and 53R in the axial direction of the crankshaft 54. Say.

  The end surface in the thickness direction of the substrate 150 may not exactly coincide with the overlapping surfaces 53L and 53R in the axial direction of the crankshaft 54. For example, the overlapping surfaces 53L and 53R may be at the same position as the substrate 150 in the axial direction of the crankshaft 54. Here, “the overlapping surfaces 53L and 53R are in the same position as the substrate 150 in the axial direction of the crankshaft 54” means that the overlapping surfaces are viewed from a direction orthogonal to the central axis L1 of the crankshaft. This means that 53L and 53R overlap the substrate 150.

As shown in FIG. 2, the substrate 150 has a first transmission gear 84 in the axial direction of the crankshaft 54.
Are arranged at the same position. Here, “the substrate 150 and the first transmission gear 84 are disposed at the same position in the axial direction of the crankshaft 54” means that when viewed from a direction orthogonal to the central axis L1 of the crankshaft 54, This means that the substrate 150 overlaps the first transmission gear 84.

  As shown in FIG. 8, when viewed from the axial direction of the crankshaft 54, the substrate 150 is disposed on the opposite side of the rotation center C3 with respect to the first line segment S1.

  As shown in FIG. 8, when viewed from the axial direction of the crankshaft 54, the substrate 150 does not overlap the rotation center C1 and the rotation center C2.

  As shown in FIG. 9, the substrate 150 has a first region 154 that overlaps the motor 60 when viewed from the axial direction of the crankshaft 54.

  As shown in FIG. 9, the electrical component 156 is disposed in the first region 154. The electrical component 156 is a switching element that supplies power to the motor 60. The electrical component 156 is disposed on the mounting surface 152.

  As shown in FIG. 9, the heat transfer sheet 158 is disposed in a region of the first region 154 where the electrical component 156 is disposed. The heat transfer sheet 158 is disposed on the back surface of the substrate 150 (the surface opposite to the mounting surface 152 in the thickness direction of the substrate 152). The heat transfer sheet 158 has a higher thermal conductivity than the coating material that coats the substrate 150. The heat transfer sheet 158 releases heat generated by the electric component 156.

  As shown in FIG. 10, the heat transfer sheet 158 contacts the inner surface of the second housing portion 52R. In other words, the first region 154 contacts the inner surface of the second housing portion 52R via the heat transfer sheet 158.

  As shown in FIG. 10, the second housing portion 52 </ b> R has a plurality of heat radiation fins 160 in a region overlapping with the heat transfer sheet 158. The plurality of heat dissipating fins 160 are formed in a region overlapping the heat transfer sheet 158 when viewed from the axial direction of the crankshaft 54 on the outer surface of the second housing portion 52R. By having the plurality of heat dissipating fins 160, heat generated by the electric component 156 is easily released.

  As shown in FIG. 11, the substrate 150 has a second region 162 that overlaps the driven gear 104 when viewed from the axial direction of the crankshaft 54.

  As shown in FIG. 11, the second region 162 includes a third region 164 that overlaps the ring magnet 132 when viewed from the axial direction of the crankshaft 54. The detection element 134 is disposed at a position overlapping the third region 164.

[Partition wall]
The partition wall 170 will be described with reference to FIGS. 2, 3, 8, 12, 13, and 14. 12 and 13 are perspective views showing the partition wall 170. FIG. In FIG. 14, the driven gear 104 is removed compared to FIG. 3.

  The partition wall 170 is arrange | positioned in the housing 52, as shown in FIG.2 and FIG.3. As shown in FIGS. 8 and 12 to 14, the partition wall 170 includes a first wall part 172, a second wall part 174, a third wall part 176, and a fourth wall part 178.

  As shown in FIG. 14, the first wall portion 172 extends in a direction orthogonal to the central axis L <b> 1 of the crankshaft 54. As shown in FIGS. 8 and 12 to 14, a through hole 180 is formed in the first wall portion 172. As shown in FIG. 14, the drive member 102 is disposed in the through hole 180. As apparent from FIGS. 2, 3, 8, and 14, the first wall portion 172 is disposed between the substrate 150 and the driven gear 104 in the axial direction of the crankshaft 54. Here, “the first wall portion 172 is disposed between the substrate 150 and the driven gear 104” means that the first wall portion 172 has teeth (second transmission) that the substrate 150 and the driven gear 104 have. It is arranged between the gear 86 and the portion engaged with the gear 86. That is, the space formed between the substrate 150 and the teeth of the driven gear 104 (the portion that meshes with the second transmission gear 86) is partitioned by the first wall portion 172.

  As shown in FIGS. 3 and 8, the second wall portion 174 extends in a direction orthogonal to the central axis L <b> 1 of the crankshaft 54. As shown in FIG. 3, the second wall portion 174 is disposed at a position different from the first wall portion 172 in the axial direction of the crankshaft 54. Here, “the second wall portion 174 is disposed at a position different from the first wall portion 172 in the axial direction of the crankshaft 54” means that the second wall portion 174 is viewed from a direction orthogonal to the central axis L1 of the crankshaft. The second wall portion 174 does not overlap the first wall portion 172.

  As shown in FIGS. 8, 12, and 13, two through holes 182 and 184 are formed in the second wall portion 174. When viewed from the axial direction of the crankshaft 54, the through hole 182 is larger than the through hole 184.

  As shown in FIG. 8, the rotation center C <b> 2 is located in the through hole 182 when viewed from the axial direction of the crankshaft 54. As apparent from FIGS. 2 and 8, the bearing 88 </ b> L is located in the through hole 182 when viewed from the axial direction of the crankshaft 54.

  As shown in FIG. 8, the output shaft 74 is positioned in the through hole 184 when viewed from the axial direction of the crankshaft 54. That is, the output shaft 74 is inserted through the through hole 184.

  As shown in FIGS. 8, 12, and 13, the third wall portion 176 is formed along the outer edge of the second wall portion 174. The third wall portion 176 extends from the one end surface in the thickness direction of the second wall portion 174 in one thickness direction.

  As shown in FIGS. 8, 12, and 13, the third wall portion 176 includes a first peripheral wall portion 186 and a second peripheral wall portion 188. The first peripheral wall portion 186 is formed around the through hole 182. The second peripheral wall portion 188 is formed around the through hole 184. One end in the circumferential direction of the first peripheral wall portion 186 and the other end in the circumferential direction of the second peripheral wall portion 188 are connected. The other circumferential end of the first peripheral wall 186 and one circumferential end of the second peripheral wall 188 are connected.

  As shown in FIG. 8, when viewed from the axial direction of the crankshaft 54, the first transmission gear 84, the second transmission gear 86, and the output gear 76 are disposed inside the third wall portion 176.

  Specifically, the first transmission gear 84 is disposed inside the first peripheral wall 186. In other words, the first transmission gear 84 is disposed at the same position as the third wall portion 176 in the axial direction of the crankshaft 54 as shown in FIG. Here, “the first transmission gear 84 is disposed at the same position as the third wall portion 176 in the axial direction of the crankshaft 54” means when viewed from a direction orthogonal to the central axis L 1 of the crankshaft 54. In addition, it means that at least a part of the first transmission gear 84 overlaps the third wall portion 176.

  Further, the output gear 76 is disposed inside the second peripheral wall portion 188. In other words, the output gear 76 is disposed at the same position as the third wall portion 176 in the axial direction of the crankshaft 54 as shown in FIG. Here, "the output gear 76 is disposed at the same position as the third wall portion 176 in the axial direction of the crankshaft 54" means that when viewed from a direction orthogonal to the central axis L1 of the crankshaft 54, It means that at least a part of the output gear 76 overlaps the third wall portion 176.

  As shown in FIG. 2, the second transmission gear 86 is arranged at a position different from the third wall portion 176 in the axial direction of the crankshaft 54. Here, “the second transmission gear 86 is disposed at a position different from the third wall portion 176 in the axial direction of the crankshaft 54” means that the second transmission gear 86 is viewed from a direction orthogonal to the central axis L 1 of the crankshaft 54. In addition, the second transmission gear 86 does not overlap the third wall 176.

  As shown in FIG. 8, the substrate 150 is disposed outside the second peripheral wall portion 188 in a direction orthogonal to the central axis L <b> 2 of the output shaft 74. That is, the space formed between the substrate 150 and the output gear 76 is partitioned by the second peripheral wall portion 188.

  As shown in FIGS. 8, 12, and 13, the fourth wall portion 178 extends in a direction orthogonal to the central axis L <b> 1 of the crankshaft 54. The fourth wall portion 178 is connected to the first wall portion 172.

  As shown in FIG. 8, the fourth wall portion 178 overlaps the substrate 150 when viewed from the axial direction of the crankshaft 54.

  In the battery-assisted bicycle 10, the crankshaft 54 rotates in the forward rotation direction when the driver pedals the pedals 36 </ b> L and 36 </ b> R. When the crankshaft 54 rotates in the forward rotation direction, the connecting shaft portion 56A rotates in the forward rotation direction. When the connecting shaft portion 56A rotates in the forward rotation direction, the drive member 102 rotates in the forward rotation direction. When the driving member 102 rotates in the forward rotation direction, the driven gear 104 rotates in the forward rotation direction. When the drive member 102 rotates in the backward rotation direction, that is, when the crankshaft 54 rotates in the backward rotation direction, the drive member 102 rotates relative to the driven gear 104. When the driven gear 104 rotates in the forward rotation direction, the drive sprocket 58 rotates in the forward rotation direction. The rotational force of the drive sprocket 58 is transmitted to the driven sprocket 26 via the chain 32.

  Torque is generated in the crankshaft 54 when the driver pedals the pedals 36L and 36R. Torque generated in the crankshaft 54 is detected by the torque detector 56B. When the state where the torque generated in the crankshaft 54 exceeds a predetermined reference value continues for a certain period or longer, the rotor 72 of the motor 60, that is, the output shaft 74 rotates in the forward rotation direction. When the output shaft 74 rotates in the forward rotation direction, the output gear 76 rotates in the forward rotation direction. When the output gear 76 rotates in the forward rotation direction, the first transmission gear 84 rotates in the backward rotation direction. When the first transmission gear 84 rotates in the backward rotation direction, the second transmission gear 86 rotates in the backward rotation direction. When the second transmission gear 86 rotates in the backward rotation direction, the driven gear 104 rotates in the forward rotation direction. When the driven gear 104 rotates in the forward rotation direction, the attachment shaft portion 118 rotates in the forward rotation direction. When the attachment shaft portion 118 rotates in the forward rotation direction, the drive sprocket 58 rotates in the forward rotation direction. As a result, pedaling by the driver is assisted.

  Here, in the battery-assisted bicycle 10, the rotation detection device 130 detects the rotation of the crankshaft 54. Therefore, not only the torque generated in the crankshaft 54 but also the rotation of the crankshaft 54 can be referred to and the state of pedaling by the driver can be grasped. As a result, the state of pedaling by the driver can be accurately grasped, so that, for example, it becomes easier to detect a failure and more accurate assistance can be performed.

  Further, the battery-assisted bicycle 10 includes a drive unit 50. The drive unit 50 includes a crankshaft 54, a motor 60, a transmission shaft 82 and a substrate 150.

  The transmission shaft 82 extends in parallel to the central axis L1 of the crankshaft 54. The substrate 150 has a mounting surface 152 that extends in a direction orthogonal to the central axis L1 of the crankshaft 54.

  The motor 60 includes a rotor 72, an output shaft 74, and an output gear 76. The output shaft 74 rotates together with the rotor 72 and extends parallel to the central axis L1 of the crankshaft 54. The output gear 76 is disposed on the output shaft 74.

  The drive unit 50 further includes a first transmission gear 84, a second transmission gear 86, and a driven gear 104. The first transmission gear 84 is disposed on the transmission shaft 82, meshes with the output gear 76, and has more teeth than the output gear 76. The second transmission gear 86 is disposed on the transmission shaft 82. The driven gear 104 is disposed on the crankshaft 54, meshes with the second transmission gear 86, and has more teeth than the second transmission gear 86.

  Of the motor 60, the first transmission gear 84, and the driven gear 104, the member having the largest diameter when viewed from the axial direction of the crankshaft 54 is defined as the first member 104, and the member having the next largest diameter is defined as the second member. 60. In this case, the substrate 150 is disposed between the first member 104 and the second member 60 in the axial direction of the crankshaft 54.

  In the drive unit 50, the substrate 150 is disposed between the driven gear 104 (first member) and the motor 60 (second member) in the axial direction of the crankshaft 54. Therefore, the size of the drive unit 50 in the axial direction of the crankshaft 54 can be reduced.

  In the drive unit 50, the first transmission gear 84 has more teeth than the output gear 76. The driven gear 104 has more teeth than the second transmission gear 86. Therefore, in the drive unit 50, the size of the drive unit 50 in the axial direction of the crankshaft 54 can be reduced while ensuring a reduction ratio.

  In the present embodiment, the substrate 150 is coated with a waterproof coating material. Therefore, the waterproofness of the substrate 150 can be ensured.

  Further, the mounting surface 152 of the substrate 150 extends in the vertical direction in a state where the drive unit 50 is disposed on the battery-assisted bicycle 10. Therefore, even if water adheres to the substrate 150, it is difficult for water to stay on the substrate 150. As a result, the waterproofness of the substrate 150 is further improved.

  In the drive unit 50, the substrate 150 has regions 154 and 162 that overlap at least one of the first member 104 and the second member 60 when viewed from the axial direction of the crankshaft 54. In this case, the size of the drive unit 50 when viewed from the axial direction of the crankshaft 54 can be reduced.

  The drive unit 50 further includes a housing 52. The housing 52 accommodates the motor 60, the first transmission gear 84, the driven gear 104, and the substrate 150. At least a part of the region 154 contacts the inner surface of the housing 52.

  In this case, the heat of the board 150 and the electrical components mounted on the board 150 can be easily released.

  In the present embodiment, the portion of the housing 50 that contacts the substrate 150 is made of a metal material. Therefore, the heat of the substrate 150 is easily released.

  In the present embodiment, the substrate 150 is in contact with the inner surface of the housing 52 via the heat transfer sheet 158. Therefore, it becomes easier to release the heat of the substrate 150.

  In the present embodiment, a plurality of radiating fins 160 are provided in a portion of the housing 50 that contacts the substrate 150. Therefore, it becomes easier to release the heat of the substrate 150.

  In the drive unit 50, an electrical component 156 is disposed in the region 154. In this case, the heat generated by the electrical component 156 can be easily released.

  In the drive unit 50, one of the first member 104 and the second member 60 is a motor 60. The region 154 is a first region 154 that overlaps the motor 60. The electrical component 156 is a component that supplies power to the motor 60.

  The electric power required for driving the motor 60 is larger than the electric power for control. Therefore, the electrical component 156 is likely to generate heat. In the drive unit 50, the first region 154 in which the electric component 156 is disposed is brought into contact with the inner surface of the housing 52. Therefore, the heat generation of the electrical component 156 is suppressed.

  In the drive unit 50, when viewed from the axial direction of the crankshaft 54, the substrate 150 is third with respect to a line segment S 1 connecting the rotation center C 1 of the first member 104 and the rotation center C 2 of the second member 60. The member 84 is disposed on the opposite side to the rotation center C3. In this case, the size of the drive unit 50 when viewed from the axial direction of the crankshaft 54 can be reduced. In addition, it is easy to secure a space in which the substrate 150 is disposed.

  In the drive unit 50, the substrate 150 is disposed at the same position as the third member 84 in the axial direction of the crankshaft 54. In this case, the size of the drive unit 50 in the axial direction of the crankshaft 54 can be reduced.

  In the drive unit 50, one of the first member 104 and the second member 60 is a driven gear 104. The region 162 is a second region 162 that overlaps the driven gear 104. A detection element 134 that detects the rotation of the crankshaft 54 is disposed in the second region 162.

  In this case, it is not necessary to separately provide a substrate for arranging the detection element 134 in addition to the substrate 150.

  The drive unit 50 further includes a partition wall 170. The partition wall 170 is disposed between at least one of the output gear 76, the first transmission gear 84, and the driven gear 104 and the substrate 150.

  In this case, it becomes difficult for grease or metal powder to adhere to the substrate 150.

  Specifically, the second peripheral wall portion 188 is disposed between the substrate 150 and the output gear 76. Therefore, it is possible to suppress the grease arranged at the meshing portion between the output gear 76 and the first transmission gear 84 from being scattered on the rotation of the output gear 76 and adhering to the substrate 150.

  Further, the first wall portion 172 is disposed between the substrate 150 and the teeth of the driven gear 104 (the portion that meshes with the second transmission gear 86). Therefore, the grease arranged at the meshing portion between the driven gear 104 and the second transmission gear 86 and the metal powder generated by the contact between the metals repeated at the meshing portion between the driven gear 104 and the second transmission gear 86 are generated. As a result of being scattered with the rotation of the driven gear 104, it is possible to suppress adhesion to the substrate 150.

  The drive unit 50 further includes a one-way clutch 56C. The one-way clutch 56C is disposed on the crankshaft 54. The one-way clutch 56 </ b> C transmits a rotational force that rotates the crankshaft 54 in the first direction to a drive sprocket 58 disposed on the crankshaft 54. The one-way clutch 56 </ b> C does not transmit the rotational force that rotates the crankshaft 54 in the direction opposite to the first direction to the drive sprocket 58. The one-way clutch 56 </ b> C includes a driven gear 104.

  In the drive unit 50, the driven gear 104 includes an attachment shaft portion 118 to which the drive sprocket 58 is attached.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 10 Electric assist bicycle 50 Drive unit 52 Housing 54 Crankshaft 56C One-way clutch 58 Drive sprocket 60 Motor 72 Rotor 74 Output shaft 76 Output gear 78R Bearing (first bearing)
80 Electrical component 82 Transmission shaft 84 First transmission gear 86 Second transmission gear 88L Bearing (second bearing)
104 Driven gear 118 Mounting shaft portion 150 Substrate 152 Mounting surface 154 First region 156 Electrical component 162 Second region 170 Partition wall C0 Center of the axial length of the output shaft C1 Center of rotation of the crankshaft C2 Center of rotation of the output shaft C3 Rotation center of transmission shaft

Claims (12)

A drive unit used for a battery-assisted bicycle,
A crankshaft,
A motor,
A transmission shaft extending parallel to the central axis of the crankshaft;
A substrate having a mounting surface extending in a direction perpendicular to the center axis of the crankshaft,
The motor is
A rotor,
An output shaft that rotates with the rotor and extends parallel to a central axis of the crankshaft;
An output gear disposed on the output shaft,
The drive unit further includes:
A first transmission gear disposed on the transmission shaft, meshing with the output gear, and having more teeth than the output gear;
A second transmission gear disposed on the transmission shaft;
A driven gear disposed on the crankshaft, meshed with the second transmission gear, and having more teeth than the second transmission gear;
Of the motor, the first transmission gear, and the driven gear, a member having the largest diameter when viewed from the axial direction of the crankshaft is defined as a first member, and a member having the next largest diameter is defined as a second member. In this case, the substrate is disposed between the first member and the second member in the axial direction of the crankshaft. The drive unit according to claim 1,
The board has a region that overlaps at least one of the first member and the second member when viewed from the axial direction of the crankshaft. The drive unit according to claim 2,
The drive unit further includes a housing that houses the motor, the first transmission gear, the driven gear, and the substrate,
The drive unit, wherein at least a part of the region is in contact with the inner surface of the housing. The drive unit according to claim 3,
A drive unit in which electrical components are arranged in the region. The drive unit according to claim 4,
One of the first member and the second member is the motor,
The region is a first region overlapping the motor,
The electric component is a drive unit that supplies electric power to the motor. It is a drive unit given in any 1 paragraph of Claims 1-5,
When viewed from the axial direction of the crankshaft, the substrate is opposite to the rotation center of the third member with respect to a line segment connecting the rotation center of the first member and the rotation center of the second member. Drive unit arranged on the side. It is a drive unit given in any 1 paragraph of Claims 1-6,
The drive unit is disposed at the same position as the third member in the axial direction of the crankshaft. The drive unit according to claim 2,
One of the first member and the second member is the driven gear,
The region is a second region overlapping the driven gear,
The drive unit, wherein a detection element that detects rotation of the crankshaft is disposed in the second region. The drive unit according to any one of claims 1 to 8,
A drive unit further comprising a partition wall disposed between at least one of the output gear, the first transmission gear, and the driven gear and the substrate. It is a drive unit given in any 1 paragraph of Claims 1-9,
A rotational force that is disposed on the crankshaft and rotates the crankshaft in a first direction is transmitted to a drive sprocket disposed on the crankshaft, and the crankshaft is moved in a direction opposite to the first direction. A one-way clutch that does not transmit the rotational force to rotate to the drive sprocket;
The one-way clutch is a drive unit including the driven gear. The drive unit according to claim 10, wherein
The driven gear includes a drive shaft to which the drive sprocket is attached.   A battery-assisted bicycle comprising the drive unit according to any one of claims 1 to 11.

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