JP2016088277A - Drive unit and electric assist bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength of a drive unit for an impact from an external part while suppressing increase of a weight of the drive unit used on an electric assist bicycle.SOLUTION: In a drive unit 40 mounted on an electric assist bicycle 1, a shaft center L3 of a motor shaft 64 is located on the lower side in the bicycle mount state than a straight line A1 formed by connecting the shaft center L1 of a crank shaft 41 and a shaft center L2 of an output shaft 81 as seen from a shaft direction of a crank shaft 41. At least a part 61La of a lower part in a bicycle mount state of a housing 51 has a shape corresponding to a motor 61 on a part for housing the motor 61 as seen from a shaft direction of the crank shaft 41. The motor shaft 64 is located on the rear side from the crank shaft 41 in a vehicle longitudinal direction of the bicycle mount state.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a drive unit used for a battery-assisted bicycle. Specifically, the present invention relates to a drive unit in which a motor is disposed in a housing.

  There is known a battery-assisted bicycle that assists a driver's pedaling force (hereinafter referred to as a pedaling force) with a 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 Nos. 2007-176354 and 2007-91159. The drive unit is mounted at a position including a crankshaft to which a pedal is attached in the battery-assisted bicycle.

JP 2007-176354 A JP 2007-91159 A

  By the way, the drive unit is mounted in the vicinity of the crankshaft of the pedal of the battery-assisted bicycle. The drive unit is mounted on the battery-assisted bicycle in a state where it is not completely covered with other members. Since the drive unit is disposed at a short distance from the road surface, and a part of the drive unit is exposed, for example, when the battery-assisted bicycle rides on the curb, the curb may come into contact with the drive unit. . Besides the curb, the drive unit may come into contact with obstacles on the road.

  In order to protect the drive unit from obstacles such as curbs, the thickness of the lower part of the housing of the drive unit may be increased, or an impact-resistant member may be separately attached. However, making the lower part of the drive unit a strong structure causes an increase in the weight of the drive unit.

  An object of the present invention is to improve the strength of a drive unit against an external impact while suppressing an increase in the weight of the 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

  A drive unit according to a first aspect of the present invention is mounted on a battery-assisted bicycle, and is supported in the housing, a first sprocket that transmits a pedaling force to the chain, and the first unit. A crankshaft that supports the sprocket, a motor disposed in the housing, a motor shaft provided in the motor, a second sprocket that transmits rotation of the motor to a chain, and a housing that is supported in the housing. And an output shaft for supporting the second sprocket. The axis of the motor shaft is positioned below the straight line connecting the axis of the crankshaft and the axis of the output shaft in the bicycle mounted state when viewed from the axial direction of the crankshaft. At least a part of the lower portion of the housing in a bicycle-mounted state has a shape corresponding to the motor in a portion that accommodates the motor when viewed from the axial direction of the crankshaft. The motor shaft is positioned behind the crankshaft in the vehicle front-rear direction in a bicycle-mounted state.

  According to the drive unit of the above aspect, the shaft center of the motor shaft is positioned below the straight line connecting the shaft center of the crank shaft and the shaft center of the output shaft in the bicycle mounted state, and the motor shaft is Is positioned rearward, and at least a part of the lower portion of the housing in a bicycle-mounted state has a shape along the motor in a portion that accommodates the motor when viewed from the axial direction of the crankshaft. Since the structure of the peripheral portion of the motor in the housing has excellent strength, the lower portion of the drive unit has excellent strength by arranging the motor in the above-described manner. Therefore, even when an impact is applied to the drive unit from below the drive unit (for example, when the drive assist bicycle is in contact with the curb when the drive unit is mounted on the drive assist bicycle), the drive unit has excellent resistance to resistance. Exhibits impact and protects the structure inside the housing of the drive unit.

  Further, according to the drive unit of the above aspect, excellent strength can be obtained by changing the position of the motor to a position where the obstacle comes into contact with the drive unit without providing a separate member to increase the strength against impact. Thus, an increase in the weight of the drive unit is suppressed. As a result, according to the drive unit of the above aspect, it is possible to obtain an excellent strength against an external impact while suppressing an increase in weight.

FIG. 1 is a right side view showing a battery-assisted bicycle according to the present embodiment. FIG. 2 is a right side view of the drive unit and the driven sprocket of the battery-assisted bicycle according to the present embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a left side view of the drive unit. FIG. 5 is a right side view of the drive unit. FIG. 6 is a right side cross-sectional view showing only a part of the structure of the drive unit. FIG. 7 is a perspective view of the drive unit as viewed obliquely from the lower left.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the dimension of the structural member in each figure does not represent the dimension of an actual structural member, the dimension ratio of each structural member, etc. faithfully.

  In the following description, front, rear, left, and right mean front, rear, left, and right as viewed from a user who is seated on the seat 24 of the battery-assisted bicycle 1 while grasping the handle 23.

[Embodiment 1]
[Overall configuration of battery-assisted bicycle]
FIG. 1 is a right side view showing the battery-assisted bicycle 1 according to the first embodiment. FIG. 2 is a right side view showing the drive unit 40 and the driven sprocket 45 of the battery-assisted bicycle 1 according to the first embodiment.

  As shown in FIG. 1, the battery-assisted bicycle 1 has a body frame 11. The body frame 11 extends in the front-rear direction. The vehicle body frame 11 includes a head pipe 12, a down frame 13, a seat frame 14, a pair of chain stays 16, and a pair of seat stays 17. The head pipe 12 is disposed at the front portion of the battery-assisted bicycle 1. The front end of the down frame 13 is connected to the head pipe 12. The down frame 13 extends in the front-rear direction. The down frame 13 extends obliquely downward. The seat frame 14 is connected to the rear end of the down frame 13. The seat frame 14 extends upward and obliquely rearward from the rear end of the down frame 13.

  As shown in FIG. 2, a bracket 15 is attached to the rear end of the down frame 13. A pair of chain stays 16 are connected to the rear end of the bracket 15. The pair of chain stays 16 are arranged so as to sandwich the rear wheel 22 from the left and right. As shown in FIG. 1, one end of a seat stay 17 is connected to the rear end of each chain stay 16. The pair of seat stays 17 are arranged so as to sandwich the rear wheel 22 from the left and right. As shown in FIG. 1, the other end of each seat stay 17 is connected to the upper portion of the seat frame 14.

  A handle stem 25 is rotatably inserted into the head pipe 12 as shown in FIG. A handle 23 is fixed to the upper end of the handle stem 25. A front fork 26 is fixed to the lower end of the handle stem 25. A front wheel 21 is rotatably supported on the lower end of the front fork 26 by an axle 27. A front wheel rotation detector (not shown) that detects the rotation speed of the front wheel 21 is disposed on the axle 27.

  Grips 73 are attached to the left and right ends of the handle 23, respectively. A left brake lever 74 is attached to the left part of the handle 23, and a right brake lever 75 is attached to the right part of the handle 23. The left brake lever 74 is a lever for operating a brake (not shown) of the rear wheel 22. The right brake lever 75 is a lever for operating a brake (not shown) of the front wheel 21.

  As shown in FIG. 1, a seat pipe 28 is inserted into the cylindrical seat frame 14. A seat 24 is provided at the upper end of the seat pipe 28.

  A rear wheel 22 is rotatably supported by an axle 29 at the rear ends of the pair of chain stays 16. A driven sprocket 45 coaxial with the axle 29 is provided on the right side of the rear wheel 22. The driven sprocket 45 is connected to the rear wheel 22 via a one-way clutch (not shown). The driven sprocket 45 is provided with a rear wheel rotation detector (not shown) that detects the rotational speed of the rear wheel 22.

  A chain cover 47 is attached to the body frame 11. The chain cover 47 has a main cover 48 and a sub cover 49. The main cover 48 extends in the front-rear direction. The main cover 48 covers the right front portion of the drive unit 40 and the chain 46. The sub cover 49 covers the right rear portion of the drive unit 40.

  As shown in FIG. 1, a battery unit 35 is disposed behind the seat frame 14. The battery unit 35 supplies power to the electric motor 61 (see FIG. 2) of the drive unit 40. The battery unit 35 includes a battery and a battery control unit (not shown). The battery is a chargeable / dischargeable rechargeable battery. The battery control unit controls the charging / discharging of the battery, and monitors the output current and remaining capacity of the battery.

  FIG. 3 is a cross-sectional view of the drive unit 40 of FIG. 2 taken along line III-III. As shown in FIG. 3, the drive unit 40 includes a main body 51, a crankshaft 41, a drive force generator 60, a chain tensioner 86, and a control board 38.

  The main body 51 includes a housing lid 52 and a housing main body 53. The housing lid body 52 and the housing main body 53 are combined with each other from the left and right, and are fixed to each other by a plurality of fasteners 54. The main body 51 is attached to the bracket 15 by a fastening bracket 30. As shown in FIG. 3, the housing main body 53 includes a first housing portion 53 </ b> R that forms the right portion of the drive unit 40 and a second housing portion 53 </ b> L that forms the left portion of the drive unit 40. The first housing portion 53R is formed larger than the second housing portion 53L. The first housing portion 53R and the second housing portion 53L are divided by a wall surface 53P. The housing lid body 52 is fixed to the housing main body 53 so as to close the first housing portion 53R of the housing main body 53.

  A shaft hole 53 a through which the crankshaft 41 passes is formed in the front portion of the housing body 53. Further, a shaft hole 52 a through which the crankshaft 41 passes is formed in the front portion of the housing lid body 52. The crankshaft 41 passes through the drive unit 40 by passing through the shaft holes 53a and 52a. The crankshaft 41 is rotatably supported by the housing main body 53 and the housing lid 53 through the rolling bearings 44A and 44B.

  As shown in FIG. 1, crank arms 31 and 32 are attached to both ends of the crankshaft 41. Pedals 33 and 34 are attached to the tips of the crank arms 31 and 32, respectively. When the user steps on the pedals 33 and 34, the crankshaft 41 rotates. A chain 46 is wound around the drive sprocket 42 and the driven sprocket 45.

  As shown in FIG. 3, the rotating member 56, the one-way clutch 55, and the drive sprocket 42 are disposed on the crankshaft 41 coaxially with the crankshaft 41. The rotating member 56 and the one-way clutch 55 are accommodated in the first accommodating portion 53 </ b> R of the housing body 53. The rotating member 56 is disposed slightly to the left in the center in the left-right direction of the crankshaft 41. The rotating member 56 is substantially cylindrical. The right end of the rotating member 56 is supported by the crankshaft 41 via a cylindrical slide bearing 71. The central part and the left part of the rotating member 56 are connected to the crankshaft 41. The center part and the left part of the rotation member 56 and the crankshaft 41 are connected by, for example, a spline structure. Thereby, the rotating member 56 rotates integrally with the crankshaft 41.

  The one-way clutch 55 is disposed on the right part of the crankshaft 41. The one-way clutch 55 includes an inner member 55a and an outer member 55b.

  The inner member 55 a is disposed on the right side of the rotating member 56. The inner member 55a has a substantially cylindrical shape and is rotatable with respect to the crankshaft 41. A drive sprocket 42 is attached and fixed to the outer peripheral surface at the right end of the inner member 55a. Thereby, the inner member 55a and the drive sprocket 42 rotate integrally. The drive sprocket 42 is disposed on the right side of the housing lid body 52.

  The outer member 55b is disposed so as to cover the right part of the rotating member 56 and the left part of the inner member 55a. The outer member 55b is substantially cylindrical. The outer member 55b and the rotating member 56 are connected. The outer member 55b and the rotation member 56 are connected by, for example, a spline structure. Thereby, the outer member 55b and the rotation member 56 rotate integrally.

  The outer member 55b and the inner member 55a are forwardly rotated from the outer member 55b to the inner member 55a (referred to as a clockwise direction when the battery-assisted bicycle 1 is viewed from the right side as shown in FIG. 1, the same applies hereinafter). It is connected to transmit only the rotational force. The outer member 55b and the inner member 55a are connected by, for example, a ratchet structure. The rotational force in the backward rotation direction (referred to as a counterclockwise direction when the battery-assisted bicycle 1 is viewed from the right side as shown in FIG. 1; hereinafter the same) is not transmitted from the outer member 55b to the inner member 55a.

  The crankshaft 41, the drive sprocket 42, the one-way clutch 55, and the rotating member 56 are configured as described above. As a result, when the user steps on the pedals 33 and 34 to advance the battery-assisted bicycle 1 and rotates the crankshaft 41 in the forward rotation direction, the pedaling force of the user is transferred from the crankshaft 41 to the rotating member 56. And the outer member 55b. The rotation of the outer member 55b in the forward rotation direction is transmitted to the inner member 55a. For this reason, the drive sprocket 42 attached to the inner member 55a rotates in the forward rotation direction. On the other hand, when the user rotates the crankshaft 41 in the backward rotation direction, the rotation in the backward rotation direction is not transmitted from the outer member 55b to the inner member 55a due to the ratchet structure. Therefore, the inner member 55a and the drive sprocket 42 do not rotate in the backward rotation direction.

  As shown in FIG. 3, the drive unit 40 is provided with a torque detector 57 near the outer periphery of the rotating member 56. The torque detector 57 is accommodated in the first accommodating portion 53 </ b> R of the housing body 53. The torque detector 57 detects the torque generated in the crankshaft 41 by the pedal effort. The torque detector 57 is, for example, a magnetostrictive torque sensor. In addition to the torque detector 57, the drive unit 40 may be provided with a crank rotation detector (not shown), for example.

  The torque detector 57 is not limited to a magnetostrictive torque sensor as long as the pedal depression force can be detected. The torque detector 57 may be configured to detect the torque of the crankshaft 41 from the tension generated in the chain 46 without directly detecting the torque of the crankshaft 41.

  As shown in FIG. 3, a driving force generation unit 60 is disposed in the center of the main body 51 in the front-rear direction. The driving force generator 60 includes an electric motor 61, an output shaft 81, and a gear 82.

  The electric motor 61 is accommodated in the second accommodating portion 53 </ b> L of the housing body 53. A motor cover 65 that covers the left side of the electric motor 61 is attached to the housing body 53. The motor cover 65 is fixed to the housing main body 53 by a plurality of fasteners 68. The electric motor 61 generates an auxiliary driving force for assisting the travel of the battery-assisted bicycle 1 by the pedal effort based on a control signal output from an assist control unit (not shown) of the control board 38.

  As shown in FIG. 3, the electric motor 61 has a stator 62, a rotor 63, and a motor shaft 64. The stator 62 is fixed to the housing body 53. A shaft hole 53c through which the motor shaft 64 passes is formed in the wall surface 53P of the housing body 53. A motor shaft support portion 65 c that supports the motor shaft 64 is formed on the right side surface of the motor cover 65. The motor shaft 64 passes through the shaft hole 53c and is supported by the motor shaft support portion 65c, thereby being positioned from the second housing portion 53L to the first housing portion 53R. The motor shaft 64 is rotatably supported by the housing body 53 and the motor cover 65 via rolling bearings 66 and 67. A rotor 63 is fixed to the motor shaft 64. A gear groove 64a is formed on the outer periphery of the motor shaft 64 from the right end toward the center. In addition, the electric motor 61 may include, for example, a motor rotation detection unit (not shown).

  A shaft hole 52 b through which the output shaft 81 passes is formed in the rear portion of the housing lid portion 52. An output shaft support portion 53 b that supports the output shaft 81 is formed on the rear and right side of the housing body 53. The output shaft 81 penetrates the shaft hole 52b and is supported by the output shaft support portion 53b, so that the output shaft 81 is positioned so as to protrude rightward from the first housing portion 53R. The output shaft 81 is rotatably supported by the housing lid 52 and the housing main body 53 via rolling bearings 83 and 84.

  A gear 82 is attached to the output shaft 81 via a one-way clutch 85. The gear 82 is disposed coaxially with the output shaft 81 between the rolling bearing 83 and the rolling bearing 84. The gear 82 meshes with a gear groove 64 a formed on the motor shaft 64 of the electric motor 61. The gear groove 64a and the gear 82 formed in the motor shaft 64 constitute a reduction gear. In the present embodiment, when the electric motor 61 operates, the motor shaft 64 rotates in the forward rotation direction. For this reason, the gear 82 rotates in the backward rotation direction by the rotation of the motor shaft 64 in the forward rotation direction.

  The one-way clutch 85 is configured to transmit only the rotation in the backward rotation direction generated in the gear 82 or the output shaft 81. For this reason, when the electric motor 61 operates and the gear 82 rotates in the backward rotation direction, the rotation is transmitted to the output shaft 81 and the output shaft 81 rotates in the backward rotation direction. On the other hand, even if rotation in the forward direction occurs on the output shaft 81, rotation in the forward direction is not transmitted to the gear 82.

  As shown in FIG. 3, a resin cover 59 that covers the gear 82 and the right side of the motor shaft 64 is attached to the housing main body 53. The control board 38 is disposed on the right side of the resin cover 59 and is fixed to the resin cover 59 and the housing main body 53 by a fastening bracket 39.

  An auxiliary sprocket 43 is connected to the right end of the output shaft 81 and to the right of the resin cover 59. The auxiliary sprocket 43 and the output shaft 81 are connected by, for example, a spline structure. The auxiliary sprocket 43 rotates integrally with the output shaft 81. Thereby, when the electric motor 61 is operated, the rotation of the motor shaft 64 of the electric motor 61 is transmitted to the auxiliary sprocket 43 via the gear 82, the one-way clutch 85, and the output shaft 81. That is, the auxiliary driving force generated by the driving force generator 60 is transmitted from the output shaft 81 to the auxiliary sprocket 43, and the auxiliary sprocket 43 rotates in the backward rotation direction.

  As shown in FIG. 3, a chain tensioner 86 is disposed at the rear part of the main body 51. A tension sprocket 90 is rotatably attached to the chain tensioner 86 by a support bolt 89. As shown in FIG. 2, one end of the chain tensioner 86 is rotatably connected to the housing lid 52 by a support bolt 88. The other end of the chain tensioner 86 is connected to the housing lid 52 via a tension spring 87. A chain 46 is wound around the tension sprocket 90 so as to push the tension sprocket 90 rearward and downward. The chain tensioner 86 applies an appropriate tension to the chain 46 by the elastic force of the tension spring 87.

  As shown in FIG. 2, in the battery-assisted bicycle 1 of the present embodiment, the drive sprocket 42 and the auxiliary sprocket 43 transmit driving force to the rear wheel 22 via a chain 46. Specifically, the pedal depression force generated when the user steps on the pedals 33 and 34 causes the driving sprocket 42 to rotate in the forward rotation direction and the driving force to rotate the rear wheel 22 in the forward rotation direction via the chain 46. As transmitted. The rotational force generated by the operation of the electric motor 61 is transmitted as an auxiliary driving force that rotates the auxiliary sprocket 43 in the backward rotation direction and rotates the rear wheel 22 in the forward rotation direction via the chain 46. Thereby, the pedal depression force generated by the user depressing the pedals 33 and 34 is assisted by the driving force output from the electric motor 61.

  FIG. 4 is a left side view of the drive unit 40. FIG. 5 is a right side view of the drive unit 40. The positional relationship among the crankshaft 41, the output shaft 81, the electric motor 61, and the motor shaft 64 will be described with reference to FIGS. The arrows indicating the vertical direction and the front-rear direction shown in FIGS. 4 and 5 indicate the vertical direction and the front-rear direction when the drive unit 40 is mounted on the battery-assisted bicycle 1. In the following expression, when the end portion of the shaft such as the front end or the lower end of the crankshaft 41 is expressed, the shaft is grasped in consideration of the radial thickness. On the other hand, the expression “axial center” means a straight line that becomes the center of rotation of the cylindrical “axis” or the center of rotation of the shaft when viewed from the axial direction.

  As shown in FIGS. 4 and 5, the shaft center L <b> 3 of the motor shaft 64 is positioned below a straight line A <b> 1 that connects the shaft center L <b> 1 of the crankshaft 41 and the shaft center L <b> 2 of the output shaft 81. More preferably, the axis L3 of the motor shaft 64 is positioned below the axis L1 of the crankshaft 41 and below the axis L2 of the output shaft 81. Thereby, more excellent strength can be obtained against an impact applied from below the drive unit 40.

  As shown in FIG. 5, the motor 61 is preferably positioned below the lower end 41 l of the crankshaft 41. As described above, the lower end 41l of the crankshaft 41 means the lower end when the radial thickness of the crankshaft 41 is taken into consideration. In other words, it means the lower end of a cross section obtained by cutting the crankshaft 41 along a plane perpendicular to the axial direction. Moreover, the lower end here means the lower end (portion closest to the road surface) when the drive unit 40 is mounted on the battery-assisted bicycle 1. Specifically, it is desirable that the upper end 61 u of the motor 61 is located below the lower end 41 l of the crankshaft 41. Thereby, more excellent strength can be obtained against an impact applied from below the drive unit 40. The upper end 61u of the motor 61 means the upper end of the stator 62 of the motor 61. Moreover, the upper end here means the upper end in a state where the drive unit 40 is mounted on the battery-assisted bicycle 1.

  The position of the motor 61 in the vehicle front-rear direction will be described. The shaft center L3 of the motor shaft 64 is positioned behind the rear end 41r of the crankshaft 41, as shown in FIGS. The motor shaft 64 is disposed in front of the output shaft 81.

  The position of the front end 61f of the motor 61 is preferably in front of the position of the rear end 41r of the crankshaft 41, as shown in FIGS. The front end 61 f of the motor 61 means the front end of the stator 62 of the motor 61 in the vehicle front-rear direction. Similarly, the front end referred to here means a front end in a state where the drive unit 40 is mounted on the battery-assisted bicycle 1. More preferably, the position of the front end 61f of the motor 61 is between the position of the front end 41f and the position of the rear end 41r of the crankshaft 41. Note that the front end 41f and the rear end 41r of the crankshaft 41 mean a front end and a rear end in consideration of the radial thickness of the crankshaft 41. Similarly, the front end and the rear end in a state where the drive unit 40 is mounted on the battery-assisted bicycle 1 are meant. In this case, the position of the front end 61f of the motor 61 is preferably close to the position of the axis L1 of the crankshaft 41 between the position of the front end 41f and the position of the rear end 41r of the crankshaft 41. Further, it is more preferable that the position of the front end 61f of the motor 61 is the same as the position of the axis L1 of the crankshaft 41 in the vehicle longitudinal direction. Since the position of the front end 61f of the motor 61 in the vehicle front-rear direction is in front of the position of the rear end 41r of the crankshaft 41, the motor 61 can be disposed in the front portion of the drive unit 40. Further, since the position of the front end 61f of the motor 61 in the vehicle front-rear direction is behind the position of the front end 41f of the crankshaft 41, an increase in the size of the drive unit 40 is suppressed.

  FIG. 6 shows only the housing main body 53, the crankshaft 41, the output shaft 81, the gear 82, the electric motor 61, and the substrate 38 in the drive unit 40. The arrows indicating the vertical direction and the front-rear direction shown in FIG. 6 indicate the vertical direction and the front-rear direction in a state where the drive unit 40 is mounted on the battery-assisted bicycle 1. The hatched area indicated by reference numeral 53A indicates the contact surface with the housing lid 52. As shown in FIG. 6, the substrate 38 is disposed between the axis L <b> 1 of the crankshaft 41 and the axis L <b> 2 of the output shaft 81. Further, the lower edge 38 l of the substrate 38 is positioned above the lower end 61 l of the electric motor 61.

  A part of the lower portion of the housing main body 53 and the motor case 65 has a shape corresponding to the stator 62 of the motor 61 when viewed from the left as shown in FIG. A portion of the housing main body 53 that has a shape corresponding to the stator 62 of the motor 61 is referred to as a portion 61La. A portion of the motor case 65 that has a shape corresponding to the stator 62 of the motor 61 is referred to as a portion 61Lb. The portion 61La and the portion 61Lb are positioned so as to be visible from the front of the drive unit 40.

  The shapes of the portion 61La and the portion 61Lb may be a part of a concentric circle with the stator 62 when viewed from the left, or may be a part of a circle having a different center. Further, the portion 61La and the portion 61Lb may be curved as viewed from the left, may be a combination of straight lines and curves, or may be a combination of straight lines. That is, the shape of the portion 61La and the portion 61Lb is not particularly limited as long as the shape is designed in accordance with the shape of the stator 62 in order to accommodate the stator 62.

  The portion of the housing main body 53 that accommodates the motor 61 and the motor case 65 are formed more firmly than the other portions for the purpose of supporting the weight of the motor 61 and suppressing the noise and vibration of the motor 61. Yes. Specifically, it is formed to have a slightly larger thickness than other portions. The portion of the housing main body 53 that houses the motor 61 means an area defined by a set of portions of the housing main body 53 that are closest to the motor 61.

  FIG. 7 is a perspective view of the drive unit 40. As shown in FIG. 7, the housing lid 52 is formed with a flange 91 projecting outward at the lower portion. The flange 91 protrudes downward and forward. The flange 91 is positioned in front of the motor case 65 in the vehicle mounted state when viewed from the axial direction of the crankshaft 41.

  The front portion 91a of the flange 91 is thinner than the rear portion 91b. By making the thickness of the front portion 91a thinner than that of the rear portion 91b, the weight of the entire flange 91 is suppressed.

  Since the flange 91 is formed at the lower part of the housing lid 52, when the front lower part of the drive unit 40 comes into contact with an obstacle, the front part 91a of the flange 91 usually comes into contact with the obstacle first. Since the front portion 91a is thin, it is easily deformed by the impact of an obstacle. When the front unit 91a of the flange 91 is deformed at the time of contact with the obstacle of the drive unit 40, the impact of the contact is absorbed by the flange 91, and the impact is not easily transmitted to the internal structure of the housing main body 53.

  Further, when the impact when the drive unit 40 comes into contact with an obstacle is large, the obstacle contacts the front portion 91a of the flange 91 to deform the front portion 91a, and then contacts the rear portion 91b. Is also possible. In this case, since the rear portion 91b is formed to be thicker than the front portion 91a, the structure and the like inside the drive unit 40 can be protected by receiving an impact at the rear portion 91b.

[Other Embodiments]
In the above-described embodiment, it has been described that the flange 91 is formed on the housing lid 52. However, the flange 91 is not an essential configuration. If the housing lid 52 is not provided with the flange 91, when an obstacle comes into contact with the front lower portion of the drive unit 40, a portion 61 La of the housing body 53 having a shape corresponding to the stator 62 of the motor 61, In the motor case 65, the obstacle comes into contact with the portion 61Lb having a shape corresponding to the stator 62 of the motor 61. Even in this case, the portion that accommodates the first motor 6 is formed to have excellent strength, so that the structure of the drive unit 40 can be protected.

  In the above-described embodiment, the flange 91 of the housing lid 52 has been described as being configured by the front portion 91a having a small thickness and the rear portion 91b having a large thickness. However, the entire flange 91 has a uniform thickness. It may be.

  The drive unit 40 according to the first aspect of the present invention is a drive unit 40 mounted on the battery-assisted bicycle 1, and includes a housing 51, a first sprocket 42 that transmits pedal force to the chain 46, Is supported by the crankshaft 41 that supports the first sprocket 42, the motor 61 disposed in the housing 51, the motor shaft 64 provided in the motor 61, and the rotation of the motor 61 transmitted to the chain 46. 2 sprockets 43 and an output shaft 81 supported in the housing 51 and supporting the second sprocket 43. The shaft center L3 of the motor shaft 64 is positioned below the straight line A1 connecting the shaft center L1 of the crankshaft 41 and the shaft center L2 of the output shaft 81 when viewed from the axial direction of the crankshaft 41 in the bicycle mounted state. Yes. At least a part of the lower portion of the housing 51 in the bicycle mounting state has a shape corresponding to the motor 61 in a portion that accommodates the motor 61 when viewed from the axial direction of the crankshaft 41. The motor shaft 64 is positioned rearward of the crankshaft 41 in the vehicle front-rear direction of the bicycle mounted state.

  According to the drive unit 40 of the above aspect, the shaft center L3 of the motor shaft 64 is positioned below the straight line A1 connecting the shaft center L1 of the crankshaft 41 and the shaft center L2 of the output shaft 81 in the bicycle mounted state. The motor shaft 64 is positioned rearward of the crankshaft 41, and at least a part of the lower portion of the housing 51 in the bicycle mounting state is a portion in which the motor 61 is accommodated when viewed from the axial direction of the crankshaft 41. It has a shape corresponding to 61. Since the structure of the peripheral portion of the motor 61 in the housing 51 has excellent strength, the lower portion of the drive unit 40 has excellent strength by arranging the motor 61 in the above-described manner. Therefore, even when an impact is applied to the drive unit 40 from below the drive unit 40 (for example, when the battery-assisted bicycle 1 contacts the curb when the drive unit 40 is mounted on the battery-assisted bicycle 1). The unit 40 exhibits excellent impact resistance, and the structure inside the housing 51 of the drive unit 40 is protected.

  Moreover, according to the drive unit 40 of the said aspect, it was excellent by changing the position of the motor 61 to the position where an obstruction contacts the drive unit 40, without providing another member in order to raise the intensity | strength with respect to an impact. Since strength is obtained, an increase in the weight of the drive unit 40 is suppressed. As a result, according to the drive unit 40 of the said aspect, the intensity | strength excellent with respect to the impact from the outside can be obtained, suppressing a weight increase.

  The drive unit 40 according to the second aspect of the present invention is the drive unit 40 according to the first aspect, wherein at least a part of the lower part of the housing 51 in the bicycle mounting state corresponding to the motor 61 is formed. It is positioned so as to be visible from the front of the drive unit 40.

  According to the drive unit 40 of the aspect described above, at least a part of the portion 61La having a shape corresponding to the motor 61 in the lower portion of the housing 51 in the bicycle mounted state is located from the axial direction of the crankshaft 41 rather than the motor shaft 64. Since it is positioned forward in the vehicle front-rear direction, it has excellent strength against an impact applied from the front and lower side of the drive unit 40. For example, when the battery-assisted bicycle 1 is running, when the drive unit 40 hits an obstacle such as a curb on the road, the drive unit 40 receives an impact from the front and below. Even in such a situation, the drive unit 40 of the above aspect has excellent strength.

  The drive unit 40 according to the third aspect of the present invention is the control board disposed in the housing 51 in a plane substantially perpendicular to the axial direction of the crankshaft 41 in the drive unit 40 of the first or second aspect. 38. In the bicycle mounting state, the lower end of the control board 38 is positioned above the lower end of the motor 61.

  According to the drive unit 40 of the above aspect, since the lower end of the control board 38 is positioned above the lower end of the motor 61, even when an impact is applied to the drive unit 40 from below, the motor 61 From this, the control board 38 can be protected.

  The drive unit 40 according to the fourth aspect of the present invention is the drive unit 40 of any one of the first to third aspects, wherein the motor shaft 64 is in front of the output shaft 81 in the vehicle front-rear direction of the bicycle mounted state. Is positioned. The output shaft 81 is positioned below the crankshaft 41 in the bicycle mounted state.

  According to the drive unit 40 of the above aspect, since the motor shaft 64 is positioned in front of the output shaft 81 and the output shaft 81 is positioned below the crank shaft 41, the motor shaft 64 is applied from the lower portion and the front of the drive unit 40. Excellent strength against impact is obtained.

  The drive unit 40 according to the fifth aspect of the present invention is the drive unit 40 according to any one of the first to fourth aspects, wherein the shaft center L3 of the motor shaft 64 is viewed from the axial direction of the crankshaft 41. It is positioned below the axis L1 of the crankshaft 41 and the axis L2 of the output shaft 81 in the bicycle mounted state.

  According to the drive unit 40 of the above aspect, the shaft center L3 of the motor shaft 64 is positioned below the shaft center L1 of the crankshaft 41 and the shaft center L2 of the output shaft 81 in the bicycle mounted state. Excellent strength against impact applied from below the drive unit 40 is obtained.

  In the drive unit 40 according to the sixth aspect of the present invention, in the drive unit 40 of any one of the first to fifth aspects, the motor 61 is positioned below the lower end of the crankshaft 41.

  According to the drive unit 40 of the above aspect, since the motor 61 is positioned below the lower end of the crankshaft 41, excellent strength can be obtained with respect to an impact applied from below the drive unit 40.

  The drive unit 40 according to the seventh aspect of the present invention is the drive unit 40 according to any one of the first to sixth aspects, wherein the front end of the motor 61 is connected to the crankshaft 41 in the vehicle front-rear direction in a bicycle-mounted state. It is positioned in front of the rear end.

  According to the drive unit 40 of the above aspect, the front end of the motor 61 is positioned in front of the rear end of the crankshaft 41, so that it is excellent with respect to an impact applied from below and from the front of the drive unit 40. Strength is obtained.

  The drive unit 40 according to the eighth aspect of the present invention is the drive unit 40 according to any one of the first to seventh aspects, wherein the position of the front end of the motor 61 in the front-rear direction of the vehicle mounted on the bicycle is a crankshaft. It overlaps between the position of the front end of 41, and the position of a rear end.

  According to the drive unit 40 of the above aspect, since the position of the front end of the motor 61 is positioned so as to overlap the position of the crankshaft 41, the drive unit 40 is excellent against an impact applied from below and from the front of the drive unit 40. High strength.

  The drive unit 40 according to the ninth aspect of the present invention is the drive unit 40 according to the eighth aspect, so that the front end of the motor 61 overlaps the axis L1 of the crankshaft 41 in the vehicle front-rear direction of the bicycle mounted state. It is positioned.

  According to the drive unit 40 of the above aspect, the position of the front end of the motor 61 is positioned so as to overlap with the axis L1 of the crankshaft 41, so that an impact applied from below and from the front of the drive unit 40 can be prevented. Excellent strength.

  The drive unit 40 according to the tenth aspect of the present invention is the drive unit 40 according to any one of the first to ninth aspects, wherein the housing 51 includes a motor body 61 and a housing body 53 that houses the motor shaft 64; A housing lid 52 fitted to the housing main body 53. The housing lid 52 has a flange 91 that protrudes outward in the lower portion in the bicycle-mounted state.

  According to the drive unit 40 of the above aspect, the housing lid 52 has the flange 91 projecting outward in the lower part in the bicycle-mounted state. Therefore, even when an obstacle is in contact with the lower part of the drive unit 40, the flange 91 can protect the drive unit 40 from an impact by an obstacle. Further, by adjusting the strength of the flange 91 so that the flange 91 is deformed when an impact is applied to the drive unit 40, the flange 91 can absorb the impact.

  The drive unit 40 according to the eleventh aspect of the present invention is the drive unit 40 according to the tenth aspect, wherein at least a part of the flange 91 is a motor in the lower part of the housing body 53 as viewed from the axial direction of the crankshaft 41. It is positioned in front of the portion in which the vehicle 61 is mounted in the vehicle mounted state.

  According to the drive unit 40 of the above aspect, the flange 91 provided on the housing lid body 52 is positioned in front of the lower portion of the housing main body 53 in the vehicle mounted state with respect to the portion that houses the motor 61. When the front lower part of the drive unit 40 comes into contact with the obstacle, the flange 91 comes into contact with the obstacle before the motor housing part at the lower part of the housing main body 53. Therefore, when an obstacle comes into contact with the drive unit 40, the impact received by the structure inside the drive unit 40 is reduced.

  The battery-assisted bicycle 1 according to the twelfth aspect of the present invention includes the drive unit 40 according to any one of the first to eleventh aspects.

  According to the battery-assisted bicycle 1 of the present invention, since the drive unit 40 according to any one of the first to eleventh aspects is provided, an increase in the weight of the drive unit 40 is suppressed and an impact from the outside is prevented. Excellent strength can be obtained.

L1 Center axis of crankshaft L2 Centerline of output shaft L3 Centerline of motor shaft 1 Motor-assisted bicycle 40 Drive unit 41 Crankshaft 42 First sprocket 43 Second sprocket 46 Chain 51 Housing 61 Motor 64 Motor shaft 81 Output shaft

Claims (12)

A drive unit mounted on a battery-assisted bicycle,
A housing;
A first sprocket that transmits pedal force to the chain;
A crankshaft supported in the housing and supporting the first sprocket;
A motor disposed within the housing;
A motor shaft provided in the motor;
A second sprocket for transmitting the rotation of the motor to the chain;
An output shaft supported in the housing and supporting the second sprocket;
Have
The axis of the motor shaft is positioned below the straight line connecting the axis of the crankshaft and the axis of the output shaft in the bicycle mounted state when viewed from the axial direction of the crankshaft,
At least a part of the lower portion of the housing in a bicycle-mounted state has a shape corresponding to the motor in a portion that accommodates the motor when viewed from the axial direction of the crankshaft.
The drive shaft is positioned behind the crankshaft in the vehicle front-rear direction of the bicycle mounted state. The drive unit according to claim 1, wherein
A drive unit in which at least a part of a portion corresponding to the motor in a lower portion of the housing in a bicycle-mounted state is positioned so as to be visible from the front of the drive unit 40. The drive unit according to claim 1 or 2,
A control board disposed in a plane substantially perpendicular to the axial direction of the crankshaft in the housing;
The drive unit in which a lower end of the control board is positioned above a lower end of the motor in a bicycle-mounted state. In the drive unit according to any one of claims 1 to 3,
The motor shaft is positioned in front of the output shaft in the vehicle front-rear direction in a bicycle-mounted state,
The drive shaft is positioned below the crankshaft in a bicycle-mounted state. In the drive unit according to any one of claims 1 to 4,
The drive unit, wherein the axis of the motor shaft is positioned below the axis of the crankshaft and the axis of the output shaft in a bicycle-mounted state when viewed from the axial direction of the crankshaft. In the drive unit according to any one of claims 1 to 5,
The drive unit, wherein the motor is positioned below a lower end of the crankshaft. In the drive unit according to any one of claims 1 to 6,
A drive unit in which a front end of the motor is positioned in front of a rear end of the crankshaft in a vehicle front-rear direction in a bicycle-mounted state. In the drive unit according to any one of claims 1 to 7,
A drive unit in which a front end position of the motor overlaps between a front end position and a rear end position of the crankshaft in a vehicle front-rear direction in a bicycle-mounted state. The drive unit according to claim 8,
A drive unit in which a front end of the motor is positioned so as to overlap an axis of the crankshaft in a vehicle front-rear direction in a bicycle-mounted state. In the drive unit according to any one of claims 1 to 9,
The housing is
A housing body that houses the motor and the motor shaft;
A housing lid fitted to the housing body;
Including
The housing lid body has a flange projecting outward at a lower portion in a bicycle-mounted state. The drive unit according to claim 10,
At least a part of the flange is positioned in front of the lower portion of the housing body in the vehicle mounting state relative to the portion of the lower portion of the housing body that houses the motor.   A battery-assisted bicycle comprising the drive unit according to any one of claims 1 to 11.

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