Drive unit and power-assisted bicycle

Abstract

To provide a compact drive unit capable of minimizing a region around a crank shaft and a power-assisted bicycle provided with the same.SOLUTION: A drive unit 20 provided with a motor is placed at an intermediate position between a front wheel and a rear wheel. A crank shaft 7a and a motor 21 are placed at different axial centers from each other in the drive unit 20. A substrate 24 is placed in the drive unit 20. In a side view of the drive unit 20 along the crank shaft 7a, the substrate 24 is placed so as to have a portion overlapping with a stator 21c of the motor 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a drive unit that can be attached to an electrically assisted bicycle that can travel by adding auxiliary driving force generated by a motor to human driving force from pedaling force, and to an electrically assisted bicycle. [Background technology]

[0002] Electrically assisted bicycles (also called electric bicycles) are already widely known. They have a battery as a power source and a drive unit equipped with a motor powered by this battery, and by adding the auxiliary drive force (assist force) of the drive unit to the human drive force generated by the force applied to the pedals, they can be easily ridden even uphill.

[0003] Among these electrically assisted bicycles, there is one in which the drive unit incorporating the motor and other components is disposed where the crankshaft is located. In electrically assisted bicycles with this type of configuration, the relatively heavy drive unit is disposed in a low position in the center of the bicycle's fore-and-aft direction (i.e., halfway between the front and rear wheels). Therefore, compared to bicycles in which the motor is incorporated into the front or rear hub, electrically assisted bicycles with this configuration have the advantage of being easier to handle, such as making it easier to lift the front or rear wheel and easily getting over bumps in the road, as well as providing good riding stability.

[0004] The drive unit has a built-in board (also called a main board or drive board) on which various electronic components that drive and control the motor are mounted. This board has a relatively large surface area because it is equipped with large electronic components such as FETs and a relatively large number of electronic components. In addition, as shown in Patent Document 1, for example, this board is arranged around the crankshaft when viewed from the side (when viewed in the direction of the crankshaft center). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-203735 Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, there has been a trend toward electrically assisted bicycles where the distance from the crankshaft to the rear or front wheel is not much different from that of a regular bicycle, and where the bicycle functions well. However, when a drive unit with a circuit board arranged around the crankshaft is used, as the circuit board becomes larger, a larger area is required around the crankshaft, and the drive unit also becomes larger. Even if the drive unit is arranged in a clever way, it is difficult to get a good distance from the crankshaft. This creates a problem in that the distance to the rear wheel axle becomes quite long.

[0007] The present invention aims to solve the above-mentioned problems and to provide a drive unit for an electrically assisted bicycle that can be made compact, such as by minimizing the area around the crankshaft, and that can perform its functions well as a bicycle, and an electrically assisted bicycle equipped with this drive unit. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a drive unit for an electrically assisted bicycle that is attached to an electrically assisted bicycle that can travel by adding auxiliary driving force from a motor to human driving force from pedaling force, and that includes the motor, a crankshaft to which human driving force from the pedal is transmitted; a resultant force transmission body to which the manual driving force and the auxiliary driving force are transmitted; a reduction mechanism including a first reduction gear coaxial with the crankshaft, an intermediate shaft parallel to the crankshaft, and an intermediate shaft reduction gear attached to the intermediate shaft; a first substrate having a portion overlapping with the motor and a portion overlapping with the intermediate shaft reduction gear when viewed from a side along the axial direction of the crankshaft; Equipped with The crankshaft and the motor are disposed on different axes, the reduction mechanism reduces the rotation speed of the motor and transmits the reduced rotation speed to the resultant force transmission body; When viewed along a direction perpendicular to the axial direction of the crankshaft, the rotation shaft of the motor and the first substrate overlap.It is characterized by:

[0009] According to the drive unit of the present invention, a motor shaft reduction gear is formed on the rotary shaft, It is preferable that the intermediate shaft reduction gear and the motor shaft reduction gear mesh with each other.

[0010] According to the drive unit of the present invention, it is preferable that a one-way clutch is disposed between the intermediate shaft and the intermediate shaft reduction gear.

[0011] According to the drive unit of the present invention, there is provided a rotation detection body that rotates on the same rotation axis as the crankshaft; a second substrate on which a rotation sensor that detects the rotation of the rotation detection body is attached, The second substrate is preferably connected to the first substrate.

[0012] According to the drive unit of the present invention, a third substrate is provided on which a motor rotation sensor for reading the rotation speed of the motor is mounted, The third substrate is preferably connected to the first substrate.

[0013] According to the drive unit of the present invention, the area of the first substrate is preferably larger than the area of the second substrate and the area of the third substrate.

[0014] According to the drive unit of the present invention, A plurality of substrates are provided, and the substrate having a portion overlapping the stator of the motor is the substrate with the largest area among the plurality of substrates. is preferred.

[0015] The present invention also provides an electrically assisted bicycle comprising the drive unit described above. [Effects of the Invention]

[0016] According to the present invention, 1st The part of the board that overlaps with the motor stator when viewed from the side and the part overlapping with the intermediate shaft reduction gear By arranging the motor so that it has 1st The so-called sound insulation effect that can be blocked by the substrate can be further improved. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a left side view of an electric power-assisted bicycle to which a drive unit according to an embodiment of the present invention is attached; [Figure 2] FIG. 1 is a plan cross-sectional view of a drive unit of an electrically assisted bicycle according to the first embodiment; [Figure 3] A simplified right side cross-sectional view of the drive unit [Figure 4] FIG. 10 is a plan cross-sectional view of a drive unit according to a first modified example of the first embodiment of the present invention. [Figure 5] FIG. 10 is a plan cross-sectional view of a drive unit according to a second modified example of the first embodiment of the present invention. [Figure 6] FIG. 10 is a plan cross-sectional view of a drive unit of an electrically assisted bicycle according to a second embodiment of the present invention, in which the high-speed clutch is in a disengaged state; [Figure 7] A simplified cross-sectional view of the right side of the drive unit, with the high-speed clutch in the engaged state. [Figure 8] An enlarged cross-sectional plan view of the intermediate shaft and its surrounding area of the drive unit, with the high-speed clutch in a disengaged state. [Figure 9] In this plan cross-sectional view of the drive unit, the high-speed clutch is in the engaged state. [Figure 10] An enlarged cross-sectional plan view of the intermediate shaft and its surrounding area of the drive unit, with the high-speed clutch in an engaged state. [Figure 11] FIG. 1 is a simplified plan view showing a motor shaft, an intermediate shaft, a crankshaft, and reduction gears attached to these shafts of a drive unit of an electrically assisted bicycle according to a first embodiment of the present invention; [Figure 12] A simplified right-side cross-sectional view of the drive unit showing the force vectors (reaction forces) acting on the contact points of the gears. [Figure 13] FIG. 10 is a simplified right side cross-sectional view of the drive unit showing a state in which the force vector (reaction force) acts on the intermediate shaft. [Figure 14] 10 is a plan cross-sectional view of a drive unit of an electrically assisted bicycle according to a third embodiment of the present invention; [Figure 15] A simplified right-side cross-sectional view of the drive unit showing the force vectors (reaction forces) acting on the contact points of the gears. [Figure 16] FIG. 10 is a simplified right side cross-sectional view of the drive unit showing a state in which a force vector (reaction force) acts on the intermediate shaft. [Figure 17] FIG. 11 is a right side cross-sectional view of a drive unit according to a modification of the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] (First embodiment) The following describes an electrically assisted bicycle drive unit according to an embodiment of the present invention and an electrically assisted bicycle to which this drive unit is attached, with reference to the drawings. Note that the left-right and front-rear directions in the following description refer to directions in the direction of travel when a person is riding the electrically assisted bicycle 1. Furthermore, the configuration of this invention is not limited to the configuration described below.

[0019] In Fig. 1, reference numeral 1 denotes an electrically assisted bicycle to which a drive unit according to an embodiment of the present invention is attached. As shown in Fig. 1, this electrically assisted bicycle 1 includes a head pipe 2a, a front fork 2b, an upper pipe 2c, a lower pipe 2g, a vertical pipe 2d, a chain stay 2 The bicycle comprises a metal frame 2 including a front fork 2b, a seat stay 2f, a front wheel 3 rotatably attached to the lower end of the front fork 2b, a rear wheel 4 rotatably attached to the rear end of the chain stay 2e, a handlebar 5 for changing the direction of the front wheel 3, a saddle 6 on which a rider sits, cranks 7 and pedals 8 to which human-powered driving force, which is pedaling force, is applied, a drive unit (drive unit device) 20 provided with an electric motor 21 (see also FIG. 2) as a drive source for generating auxiliary driving force (assist force) and a control unit for controlling various electric components including the motor 21, a battery 12 consisting of a secondary battery for supplying driving power to the motor 21, and a power steering unit (power steering unit) attached to the handlebar 5 etc. The electrically assisted bicycle 1 is equipped with a handheld operating unit 18 that can be operated by a person or the like and that can change settings such as switching the power supply and riding mode of the electrically assisted bicycle 1, a drive sprocket (also called a front sprocket, crank sprocket, or front gear) 13 that is attached so as to rotate coaxially with the crankshaft 7a and serves as a driving force output wheel that outputs a combined force of human-powered driving force and auxiliary driving force, a rear sprocket (sometimes called a rear gear) 14 that serves as a rear wheel attached to the hub (also called a rear hub) 9 of the rear wheel 4, and a chain 15 that serves as an endless driving force transmission body that is wound endlessly around the drive sprocket 13 and rear sprocket 14 in a rotatable state. The drive unit 20 and battery 12 also constitute a drive and power supply device (drive unit module).

[0020] The electrically assisted bicycle 1 can be driven by adding auxiliary driving force generated by the motor 21 to the human driving force generated by the pedals 8, and the combined force of the human driving force and the auxiliary driving force is transmitted from the driving sprocket 13 to the rear wheel 4 via the chain 15 and the rear sprocket 14, etc.

[0021] The battery 12 is an example of a power storage device, and a secondary battery is suitable, but the power storage device may also be a capacitor, etc. The crank 7 is made up of crank arms 7b provided on the left and right, respectively, and a crank shaft 7a connecting the left and right crank arms 7b, and pedals 8 are rotatably attached to the ends of the crank arms 7b.

[0022] As shown in Figure 1, in this electrically assisted bicycle 1, the drive unit 20 is disposed in a position midway between the front wheel 3 and the rear wheel 4, more specifically, at the location where the crankshaft 7a passes through. With this arrangement, the drive unit 20, which is relatively heavy, is disposed in the center of the fore-and-aft direction of the electrically assisted bicycle 1. This makes it easy to lift the front wheel 3 or rear wheel 4, and makes it easy to overcome steps in the road, making the body (frame 2, etc.) of the electrically assisted bicycle 1 easy to handle and providing good riding stability.

[0023] As shown in FIG. 2, the drive unit 20 has an outer shell and other components formed by a unit case 22 consisting of first to third cases 22a to 22c, and the crankshaft 7a passes laterally through the drive unit 20 (in this embodiment, a crankshaft insertion region 16 provided at the rear of the drive unit 20). The unit case 22 also has an integral mounting portion 22d for mounting the drive unit 20 at a midpoint between the front and rear wheels of the electrically assisted bicycle. Around the outer periphery of the crankshaft 7a are disposed a substantially cylindrical human power transmission body 28 to which the human-powered driving force from the crankshaft 7a is transmitted, an interlocking cylinder 23 to which the human-powered driving force from the human power transmission body 28 is transmitted, and a resultant force transmission body 29 to which the human-powered driving force from the interlocking cylinder 23 is transmitted via a one-way clutch (one-way clutch for disconnecting the auxiliary driving force) 30 and the like, and which transmits a resultant force obtained by combining the human-powered driving force and the auxiliary driving force from the motor 21 to the drive sprocket 13.

[0024] Also, inside the unit case 22 of the drive unit 20, there is a speed reduction mechanism 25 that reduces the rotation of the motor 21 and transmits it to the resultant force transmission body 29 side (intermediate shaft 40 in this embodiment), and an auxiliary drive The vehicle is provided with a motor 21 as a power (assist force) drive source, and a board (also referred to as a drive board or main board) 24 on which electronic components for various electrical controls are mounted. The board 24 and the electronic components (such as a field-effect transistor (FET) 24a, a capacitor, and a microcomputer) mounted on the board constitute a control unit. As shown in FIGS. 2 and 3, the axis of the rotating shaft 21a of the motor 21, the axis of the crankshaft 7a, and the axis of an intermediate shaft 40 (described later) are located at different positions. In this embodiment, the rotating shaft 21a of the motor 21, the intermediate shaft 40, and the crankshaft 7a are arranged in this order from the front, with the intermediate shaft 40 being located below the line connecting the crankshaft 7a and the motor shaft 21a. Also provided within drive unit 20 (more specifically, within unit case 22 of drive unit 20) are the crankshaft 7a excluding both ends, a manual power transmission body 28, interlocking cylinder 23, resultant force transmission body 29, speed reduction mechanism 25, motor 21, torque sensor 31 (described later), rotation detection body 11, rotation detector (rotation sensor) 10, etc. The manual driving force and auxiliary driving force are combined within drive unit 20, and this combined force is output from drive sprocket 13 provided outside drive unit 20 (more specifically, outside unit case 22 of drive unit 20).

[0025] The drive unit 20 will now be described in more detail. As shown in Figures 2 and 3, the crankshaft 7a is rotatably disposed by bearings (crankshaft bearings) 26, 27, penetrating the rear portion of the drive unit 20 from side to side. A cylindrical human power transmission body 28 is fitted onto the outer periphery of the left-side portion of the crankshaft 7a via a serration portion (or spline portion) 7c, so as to rotate integrally with the crankshaft 7a. A serration portion (or spline portion) 28b is also formed on the inner periphery of the human power transmission body 28 at a position corresponding to the serration portion (or spline portion) 7c of the crankshaft 7a, and this serration portion (or spline portion) 28b meshes with the serration portion (or spline portion) 7c of the crankshaft 7a.

[0026] A magnetostrictive generator 31b with magnetic anisotropy is formed on the outer peripheral surface of the power transmitting body 28, and a coil 31a is disposed around the outer periphery of the magnetostrictive generator 31b with a certain gap (space) therebetween. The magnetostrictive generator 31b and the coil 31a constitute a magnetostrictive torque sensor (power detection unit) 31. As a result, the power transmitting body 28 transmits the power from the crankshaft 7a to the power transmitting body 28, and the torque sensor 31 detects the power. In the magnetostrictive torque sensor 31, the magnetostrictive generator 31b is formed in a spiral shape that forms, for example, +45 degrees and -45 degrees with respect to the axial direction of the power transmitting body 28. When the power transmitting body 28 receives the power, distortion occurs in the magnetostrictive generator 31b on the surface of the power transmitting body 28, resulting in increased and decreased magnetic permeability. Therefore, the magnitude of the torque (power transmitting force) can be detected by measuring the inductance difference of the coil 31a.

[0027] The interlocking cylinder 23 is disposed on the outer periphery of the crankshaft 7a at a location adjacent to the right side of the power transmitting body 28, in a state in which it can rotate freely relative to the crankshaft 7a. A serration portion (or spline portion) 28a formed on the outer periphery of the right end of the power transmitting body 28 and a serration portion (or spline portion) 23a formed on the inner periphery of the left end of the interlocking cylinder 23 are fitted together, so that the interlocking cylinder 23 rotates integrally with the power transmitting body 28. In this embodiment, the serration portion (or spline portion) 23a formed on the inner periphery of the left end of the interlocking cylinder 23 is fitted from the outside into the serration portion (or spline portion) 28a of the power transmitting body 28.

[0028] In this embodiment, a rotation detecting body 11 for detecting the rotation state of the interlocking cylinder 23 is attached to the outer periphery of the left side of the interlocking cylinder 23. A rotation detector (rotation sensor) 10 as a crankshaft rotation sensor is attached and fixed to the unit case 22 side so as to face the rotation detecting body 11 from the outer periphery side. For example, the rotation detector 10 is configured by arranging optical sensors having an emitting portion and a light receiving portion in the rotation direction of the rotation detecting body 11 (not shown). First, the rotation detection body 11 has a number of teeth extending to the right in a comb-like pattern on its outer periphery. When the rotation detection body 11 has teeth, the emitted light is reflected and received, electrically detecting whether the light is incident or not by the light receiving unit of the rotation detector 10. This detected signal is input to the control unit to detect the rotation speed (amount of rotation) and direction of rotation of the interlocking cylinder 23. Note that a magnetic sensor such as a Hall IC may be provided instead of an optical sensor to detect the rotation speed (amount of rotation) and direction of rotation of the interlocking cylinder 23. Here, the interlocking cylinder 23 rotates integrally with the power transmission body 28, which in turn rotates integrally with the crankshaft 7a. Therefore, by detecting the rotation speed and direction of the interlocking cylinder 23, the rotation speed (amount of rotation) and direction of the crankshaft 7a and the pedals 8 can also be detected.

[0029] Additionally, a resultant force transmission body 29 is disposed on the outer periphery of the right portion of the interlocking cylinder 23 via a one-way clutch (one-way clutch for disconnecting the auxiliary driving force) 30. When the pedals 8 are pressed forward, the human driving force transmitted to the interlocking cylinder 23 is transmitted to the resultant force transmission body 29 via the one-way clutch 30.

[0030] The motor 21 has its rotating shaft 21a and rotor 21b rotatably supported by motor shaft bearings 32 and 33. The rotating shaft 21a of the motor 21 protrudes to the right, and a motor shaft reduction gear 39, which will be described later, is formed on the outer periphery of this protruding portion.

[0031] The reduction mechanism 25 comprises an intermediate shaft 40 disposed parallel to the crankshaft 7a, and two pairs of reduction gears 36-39 including a large-diameter reduction gear (first reduction gear: crankshaft-side reduction gear) 36 formed on the left side of the resultant force transmission body 29, forming a two-stage reduction mechanism. The reduction mechanism 25 combines the manual driving force transmitted through the crankshaft 7a with the auxiliary driving force transmitted from the motor 21, and transmits the combined force of the manual driving force and the auxiliary driving force to the resultant force transmission body 29.

[0032] The intermediate shaft 40 extends laterally in the center of the drive unit 20 in the longitudinal direction, is parallel to the crankshaft 7a, and is rotatably supported by bearings (intermediate shaft bearings) 34 and 35. A large-diameter second intermediate shaft reduction gear 37, a small-diameter third intermediate shaft reduction gear 38, and a one-way clutch 42 for disconnecting the manual drive force are attached to the intermediate shaft 40.

[0033] The one-way clutch 42 for disconnecting the manual driving force is disposed between the outer periphery of the intermediate shaft 40 and the inner periphery of the second intermediate shaft reduction gear 37, and is intended to disconnect the manual driving force from the pedals 8. That is, when the motor 21 is not driven and no auxiliary driving force is being generated, the one-way clutch 42 for disconnecting the manual driving force from the pedals 8 is disconnected by the one-way clutch 42 for disconnecting the manual driving force, so that the rotor 21b of the motor 21 does not need to be rotated. On the other hand, when the motor 21 is driven and rotating, the intermediate shaft 40 and the second intermediate shaft reduction gear 37 are connected via the one-way clutch 42, and the second and third intermediate shaft reduction gears 37, 38 rotate integrally with the intermediate shaft 40.

[0034] The small-diameter motor shaft reduction gear 39 formed on the rotating shaft 21a of the motor 21 is meshed with the large-diameter second intermediate shaft reduction gear 37. Therefore, when the motor 21 rotates and an auxiliary driving force is output, the rotation of the motor 21 is reduced, and the torque of the auxiliary driving force from the motor 21 is amplified and transmitted to the intermediate shaft 40. The small-diameter third intermediate shaft reduction gear 38 is meshed with the large-diameter first reduction gear 36 integrally formed with the resultant force transmission body 29. Therefore, the torque of the auxiliary driving force transmitted to the intermediate shaft 40 is further amplified and transmitted to the first reduction gear 36. The resultant force transmission body 29, with which the first reduction gear 36 is integrally formed, combines the manual driving force and the auxiliary driving force from the motor 21, and outputs the resultant driving force from the drive sprocket 13, which serves as a driving force output wheel. Here, the reduction ratio, which is the ratio of the rotation speed of the motor 21 to the rotation speed of the drive sprocket 13, is set to 30 to 37 (30 or more and 37 or less). The minimum radius of the moving unit 20 around the crankshaft 7a (around the crankshaft) is set to 50 mm or less.

[0035] In this embodiment, only one large-area substrate 24 is provided within the unit case 22 of the drive unit 20. When the drive unit 20 is viewed from the side along the crankshaft 7a (when viewed from the side along the axial direction of the crankshaft 7a), the substrate 24 is arranged so as to have a portion that overlaps with the stator 21c of the motor 21 (more specifically, the region where the stator core of the stator of the motor 21 is provided), as shown in FIG. 3 . In this embodiment, the substrate 24 is arranged so as to overlap with more than half of the area of the stator 21c of the motor 21. Furthermore, in this embodiment, the substrate 24 is arranged so as to overlap from the region where the stator 21c of the motor 21 is provided to the region around the crankshaft 7a.

[0036] In this embodiment, the substrate 24 is also provided in an area overlapping with the rotor 21b of the motor 21 when viewed from the side, as shown in Fig. 3. The substrate 24 is arranged so as to overlap with more than half of the area of the rotor 21b of the motor 21. That is, in this embodiment, the substrate 24 is also provided in an area overlapping with the motor 21 (the entire motor) when viewed from the side, as shown in Fig. 3, and the substrate 24 is arranged so as to overlap with more than half of the area of the motor 21.

[0037] In this embodiment, the substrate 24 is also provided in an area where the first reduction gear 36 and the stator 21c of the motor 21 do not overlap when viewed from the side, as shown in FIG. 3. As shown in FIG. 2, the substrate 24 is provided between the motor 21 and the first reduction gear 36, the resultant force transmission body 29, and the interlocking cylinder 23 when viewed from the top (or front), as shown in FIG. 2. When viewed from the front (when viewed along the front-to-rear direction), the substrate 24 is provided in an area where it overlaps with the human power transmission body 28, as shown schematically in FIG. 2. In this embodiment, the substrate 24 is provided in an area where it does not overlap with the second reduction gear 37 when viewed from the side, as shown in FIG. 3. When viewed from the front (when viewed along the front-to-rear direction), the substrate 24 is provided in an area where it does not overlap with the second reduction gear 37, as shown schematically in FIG. 2. However, the present invention is not limited to this, and the substrate 24 may be provided so that it partially overlaps with the second reduction gear 37 when viewed from the side.

[0038] In this embodiment, a rotation detector (rotation sensor) 10 (more specifically, connection legs of the rotation detector (rotation sensor) 10) serving as a crankshaft rotation sensor that reads the rotation of the crankshaft is attached to the substrate 24. In this embodiment, as shown in Fig. 2, in plan view, the substrate 24 is provided between the rotation detection body 11 and the rotation detector (rotation sensor) 10 and the bearing 26 that supports the crankshaft 7a and the like (the bearing 26 that supports the crankshaft 7a from the side opposite to the side where the drive sprocket 13 is provided) and the torque sensor 31.

[0039] In this embodiment, rotor 21b of motor 21 has a plurality of magnets arranged circumferentially such that adjacent magnets have different magnetic poles, and is provided with a substantially cylindrical magnetism imparting member 21d having similar magnetic poles. The outer periphery of magnetism imparting member 21d protrudes to the right, and a motor rotation sensor 43 that reads the rotation of motor 21 is provided facing end 21da of protruding magnetism imparting member 21d. Motor rotation sensor 43 is attached to substrate 24.

[0040] The magnetism imparting member 21d may be magnetized only at its end 21da in the same manner as the arrangement of the rotor 21b of the motor 21. In this embodiment, the magnetism imparting member 21d is arranged in the area where the reduction mechanism 25 having a plurality of reduction gears 36 to 39 is arranged (the reduction gear). The reduction gears 36-39 are also used as partition members separating the area where the reduction gears 36-39 are installed (reduction mechanism installation area) from the area where the motor 21 is installed (motor installation area). The reduction gears 36-39 are also used to prevent grease and other materials that reduce friction between the reduction gears 36-39 from entering the motor 21 side, but this is not a limitation. 21ca in Fig. 2 is a connecting wire for supplying electricity to the coil of the stator 21c.

[0041] In the above configuration, when the pedal 8 is depressed while traveling forward, a human-powered driving force based on the force applied to the pedal 8 is transmitted from the crankshaft 7a to the human power transmission body 28, the interlocking cylinder 23, and the combiner body 29, and the human-powered driving force is detected by a torque sensor 31 provided on the human power transmission body 28. An auxiliary driving force corresponding to the human-powered driving force is then transmitted to the combiner force transmission body 29 via the reduction gear 36 of the reduction mechanism 25, and the combined force at the combiner force transmission body 29 is transmitted from the drive sprocket 13 to the rear wheel 4 via the chain 15. In this way, by adding the auxiliary driving force (assist force) of the motor 21 corresponding to the human-powered driving force, the bicycle can travel easily even uphill.

[0042] Furthermore, with the above configuration, the substrate 24 is arranged so that a portion thereof overlaps with the stator 21c of the motor 21 in a side view, making it possible to employ a substrate with a sufficiently large area for the substrate 24. Furthermore, even when the substrate 24 is also arranged around the crankshaft 7a as in this embodiment, the area of the region of the substrate 24 around the crankshaft 7a can be kept small, and therefore, by devising an arrangement of the drive unit 21 (for example, by arranging the motor 21 forward of the crankshaft 7a), the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made closer to that of a general bicycle (for example, a so-called sports bicycle).

[0043] Furthermore, by arranging the board 24 so that it overlaps with at least half the area of the stator 21c of the motor 21 in a side view as described above, the area of the region around the crankshaft 7a on the board 24 can be minimized. Therefore, the distance from the crankshaft 7a to the axle of the rear wheel 4 of the electrically assisted bicycle 1 can be made closer to the functionality of a typical bicycle (for example, a so-called sports bicycle). Furthermore, by arranging the board 24 so that it has a portion that overlaps with the stator 21c of the motor 21 in a side view, the board 24 can block the sound generated by the motor 21. In other words, by arranging the board 24 so that it overlaps with at least half the area of the stator 21c of the motor 21 as described above, the sound insulation effect can be further enhanced.

[0044] In the above embodiment, the motor rotation sensor 43 that detects the rotation of the motor 21 and the rotation detector 10 serving as a crankshaft rotation sensor that detects the rotation of the crankshaft 7a are mounted on the board 24. This configuration allows the number of components in the board 24 itself within the drive unit 20 to be just one, reducing the number of components and the effort required to mount the board. In the present invention, as shown in FIG. 2, the board 24 is disposed between the motor 21 and the first reduction gear 36, the resultant force transmission body 29, and the interlocking cylinder 23 in a plan view (or front view), which provides the advantage of easily mounting the motor rotation sensor 43 and the rotation detector 10 serving as a crankshaft rotation sensor on the board 24. Furthermore, as shown in FIG. 2, the board 24 is disposed so as to overlap the rotor 21b and the magnetism imparting member 21d of the motor 21 in a side view, which provides the advantage of easily mounting the motor rotation sensor 43 on the board 24.

[0045] However, the present invention is not limited to this. As shown in FIG. 4, a crankshaft rotation sensor auxiliary board 24A on which a rotation detector 10 as a crankshaft rotation sensor is mounted may be provided separately from the board (main board) 24, and this crankshaft rotation sensor auxiliary board 24A may be connected to the board (main board) 24 (first modified example of the first embodiment). Also, as shown in FIG. 5, a motor rotation detection auxiliary board 24B on which a motor rotation sensor 43 is mounted may be provided separately from the board (main board). Alternatively, the motor rotation detection auxiliary board 24B may be provided separately from the main board 24, and connected to the board (main board) 24 (a second modification of the first embodiment). In this embodiment, as shown in FIGS. 4 and 5, in plan view, the board (main board) 24 is provided between the rotation detection body 11 or the rotation detector (rotation sensor) 10 and the bearing 26 that supports the crankshaft 7a and the like (the bearing 26 on the opposite side of the crankshaft 7a from the side on which the drive sprocket 13 is provided) and the torque sensor 31. Even in these cases, it is preferable that the board (main board) 24 is larger (has a larger area) than the crankshaft rotation sensor auxiliary board 24A and the motor rotation detection auxiliary board 24B.

[0046] Furthermore, the rotation of motor 21 is transmitted to drive sprocket 13, which serves as a driving force output wheel, via two-stage reduction mechanism 25, and the reduction ratio, which is the ratio of the rotation speed of motor 21 to the rotation speed of drive sprocket 13, is set to be 30 to 37. This allows a relatively small diameter to be used for first reduction gear 36, which is coaxial with crankshaft 7a. As a result, it is possible to reduce the diameter (radius and diameter) around crankshaft 7a in drive unit 20, and ultimately, by devising an arrangement for drive unit 21 (for example, by arranging motor 21 forward of crankshaft 7a), the distance from crankshaft 7a to the axle of rear wheel 4 can be made closer to that of a typical bicycle (for example, a so-called sports bicycle).

[0047] Furthermore, by setting the minimum radius around the crankshaft 7a of the drive unit 20 to 50 mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made even closer to that of a typical bicycle (for example, a so-called sports bicycle).By setting the minimum radius around the crankshaft 7a of the drive unit 20 to 45 mm or less, the distance from the crankshaft 7a to the axle of the rear wheel 4 can be made even closer to that of a typical bicycle (for example, a so-called sports bicycle).

[0048] (Second embodiment) In the above embodiment, the case where the reduction ratio of the reduction mechanism 25 is constant is described, but this is not limited to this, and a reduction mechanism 25A having a speed change function that can select and switch between multiple reduction ratios (two gear stages in this embodiment) may be provided within the drive unit 20.

[0049] As shown in Figures 6 to 10, the reduction mechanism 25A provided in the drive unit 20 in this embodiment has a plurality of selectable gear stages with different gear ratios (two gear stages, a low gear stage and a high gear stage in this embodiment) via a one-way clutch (a one-way clutch for disconnecting auxiliary driving force) 30 on the outer circumferential side and right side of the interlocking cylinder 23, and transmits the driving force to the resultant force transmission body 29.

[0050] The reduction mechanism 25A includes a rotation transmission cylinder 49 that is rotatably disposed on the outer periphery of the crankshaft 7a and to which the rotation of the interlocking cylinder 23 is transmitted via a one-way clutch (one-way clutch for disconnecting the auxiliary driving force) 30, a low-speed stage change gear (also referred to as a crankshaft side low-speed stage change gear) 36A that is formed integrally with and extends radially outward from the right cylindrical portion of the rotation transmission cylinder 49, a low-speed stage clutch 51 that is disposed between the rotation transmission cylinder 49 and the resultant force transmission body 29 and is capable of transmitting the driving force of the crankshaft side low-speed stage change gear 36A to the resultant force transmission body 29, and a high-speed stage change gear (also referred to as a crankshaft side high-speed stage change gear) 36A that is rotatably disposed on the outer periphery of the resultant force transmission body 29. a low-speed stage transmission gear (also referred to as intermediate shaft side low-speed stage transmission gear) 36B, a low-speed stage transmission gear (also referred to as intermediate shaft side low-speed stage transmission gear) 38A formed integrally with the intermediate shaft 40 and meshing with a tooth portion (or serration portion or spline portion) 55b formed on the inner peripheral side of a high-speed stage clutch 55 described later, an intermediate shaft tooth portion 40a formed integrally with the intermediate shaft 40 and meshing with a tooth portion (or serration portion or spline portion) 55b formed on the inner peripheral side of a high-speed stage clutch 55 described later, a high-speed stage clutch 55 provided on the outer periphery of the intermediate shaft tooth portion 40a of the intermediate shaft 40 and in an area to the right of the same, capable of transmitting a resultant force from the intermediate shaft 40 to the crankshaft side high-speed stage transmission gear 36B and resultant force transmission body 29, and is configured with engaging claws that can freely extend and retract from the main body 55a) of the high-speed clutch 55 to the outer periphery and are capable of freely engaging and disengaging with the crankshaft-side high-speed-shift gear 36B (the intermediate shaft-side high-speed-shift tooth portion, which is the so-called engaging claw portion of the high-speed clutch 55) 38B (see Figures 9 and 10), a gear change body 61 that can be freely engaged and disengaged from the outer periphery to the right side of the intermediate shaft-side high-speed-shift tooth portion 38B and that moves according to the selected gear, and a gear change movement arm 62 that engages with the gear change body 61 and moves the gear change body 61 in the crankshaft direction.

[0051] When the pedals 8 are pressed down to move forward, the human driving force transmitted to the interlocking cylinder 23 is transmitted to the rotation transmission cylinder 49. In this embodiment, the high-speed stage clutch 55 is disposed on the outer circumferential side of the intermediate shaft 40 so as to be movable in the same axial direction as the axis of the intermediate shaft 40.

[0052] Here, the crankshaft side low-speed step-transmission gear 36A has a larger diameter than the crankshaft side high-speed step-transmission gear 36B, and the intermediate shaft side low-speed step-transmission gear 38A has a smaller diameter than the intermediate shaft side high-speed step-transmission tooth portion 38B. As a result, the rotational force of the intermediate shaft 40 is transmitted at a low rotation speed to the crankshaft side low-speed step-transmission gear 36B and the rotation transmission tube 49, and is also transmitted at a high rotation speed to the crankshaft side high-speed step-transmission gear 36B.

[0053] It is preferable that the speed-changing movement arm 62 is driven by an electric speed change device 51 (shown simply in FIG. 7) provided inside the drive unit 20 (or outside the drive unit), and it is preferable that a gear change switch be provided in the handheld operation unit 18 so that the speed change can be changed. However, this is not limitative, and the speed-changing movement arm 62 (a speed change unit that is moved via a wire or the like) may be provided near the handle.

[0054] 6 and 8, when a low speed is selected, the speed changer body 61 is moved to a leftward position by the speed change movement arm 62, and the intermediate shaft side high speed stage transmission tooth portion 38B, which is made up of the retractable engagement pawl of the high speed stage clutch 55, is tilted and separated from the crankshaft side high speed stage transmission gear 36B. Therefore, the manual driving force transmitted from the interlocking cylinder 23 side via the one-way clutch (one-way clutch for disconnecting the auxiliary driving force) 30 and the auxiliary driving force transmitted from the motor side via the intermediate shaft 40 and the intermediate shaft side low speed stage transmission gear 38A are transmitted and combined to the rotation transmission cylinder 49 at a relatively low rotation speed, and this rotational driving force (resultant force) is output from the drive sprocket 13 via the low speed stage clutch 51 and resultant force transmission body 29.

[0055] 9, 10, etc., when a high speed gear is selected, the gear shifting body 61 is moved to a position closer to the right by the gear shift movement arm 62, and a pawl that can engage with the crankshaft-side high-speed step transmission gear 36B of the high-speed step clutch 55 (more specifically, the teeth of the crankshaft-side high-speed step transmission gear 36B) is made able to stand up, and the rotation of the crankshaft-side high-speed step transmission gear 36B becomes able to be transmitted to the resultant force transmission body 29. Therefore, the manual driving force transmitted from the interlocking cylinder 23 via the one-way clutch (one-way clutch for disconnecting the auxiliary driving force) 30 is transmitted to the intermediate shaft 40 via the crankshaft-side low-speed step transmission gear 36A and the intermediate shaft-side low-speed step transmission gear 38A, and is combined with the auxiliary driving force to become a resultant force. This resultant force is then transmitted through the intermediate shaft side high-speed step-transmission gear 38B and the crankshaft side high-speed step-transmission gear 36B to the resultant force transmission body 29 via the high-speed stage clutch 55 in a state of relatively high-speed rotation, and is then output from the drive sprocket 13. At this time, since the resultant force transmission body 29 rotates at a higher speed than the rotation transmission tube 49, the low-speed stage clutch 51 is idle.

[0056] In this way, by using this drive unit 20, it is possible to change the speed within the drive unit 20. Also, in this embodiment, by providing the base plate 24 and the like in the same arrangement as in the above embodiment, the same effects can be obtained. Also, the reduction ratio, which is the ratio of the rotation speed of the motor 21 to the rotation speed of the drive sprocket 13 at the low speed, is 30 to 37. By configuring the reduction ratio at high speed stages to be equal to or less than this, it is possible to use a crankshaft-side low-speed stage transmission gear 36A (and crankshaft-side high-speed stage transmission gear 36B) that is coaxial with the crankshaft 7a and has a relatively small diameter, thereby achieving the same advantageous effects.

[0057] In the above embodiment, the high-speed stage clutch 55 is provided on the outer periphery of the intermediate shaft 40, but the present invention is not limited to this and the high-speed stage clutch 55 may be provided in the outer periphery of the crankshaft 7a. Also, as in the above embodiment, a crankshaft rotation sensor auxiliary board 24A on which a rotation detector 10 serving as a crankshaft rotation sensor is attached may be provided separately from the board (main board) 24, and this crankshaft rotation sensor auxiliary board 24A may be connected to the board (main board) 24. Also, a motor rotation detection auxiliary board 24B on which a motor rotation sensor 43 is attached may be provided separately from the board (main board) 24, and this motor rotation detection auxiliary board 24B may be connected to the board (main board) 24.

[0058] In the above-described embodiments (first and second embodiments), the motor shaft (rotating shaft 21a of motor 21) is disposed forward of the crankshaft 7a, and the intermediate shaft 40 is disposed below the line connecting the crankshaft 7a and motor shaft 21a. As shown in FIG. 11, the second and third intermediate shaft reduction gears 37 and 38 attached to the intermediate shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft-side reduction gear) 36 disposed on the outer periphery of the crankshaft 7a are all helical (helical tooth) gears to reduce noise. Note that FIG. 11 corresponds to the first embodiment. Furthermore, when the motor 21 is driven and an auxiliary driving force is output, the motor shaft 21a and the motor shaft reduction gear 39 rotate clockwise (right) when viewed from the right side, the second intermediate shaft reduction gear 37 meshing with the motor shaft reduction gear 39, the intermediate shaft 40 and the third intermediate shaft reduction gear 38 rotate counterclockwise (left) when viewed from the right side, and the first crankshaft side reduction gear 36 meshing with the third intermediate shaft reduction gear 38 rotates clockwise (right) when viewed from the right side.

[0059] In this configuration, as shown in Fig. 12, when the reduction gears 36 to 39 of the reduction mechanism 25 mesh with each other, force vectors (reaction forces) V1 to P6 are generated, which act on the intermediate shaft 40 as shown in Fig. 13. Note that Fig. 12 shows the force vectors (reaction forces) acting on the contact portions of the gears (force vectors (reaction forces) that ultimately relate to the intermediate shaft 40), and Fig. 13 shows a state in which the force vectors (reaction forces) act on the intermediate shaft 40 (a state in which the force vectors are concentrated at the axis of the intermediate shaft 40).

[0060] 12 and 13, V1 is a tangential force vector on the intermediate shaft bearing 35 due to meshing between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, V2 is a separating force vector on the intermediate shaft bearing 35 due to meshing between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, and V3 is a load vector due to a thrust force on the intermediate shaft bearing 35 due to meshing between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37. In addition, V4 is a tangential force vector on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, V5 is a separating force vector on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, V6 is a load vector due to the thrust force on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, and V7 is a reaction force (resultant force) vector acting (combined) on the intermediate shaft 40.

[0061] According to the above-described arrangement, the force vectors V1 to P6 generated on the intermediate shaft 40 when the reduction gears 36 to 39 mesh with each other rarely cancel each other out, and therefore, a relatively large force vector V7 acts on the intermediate shaft 40 when these force vectors V1 to P6 are combined. Therefore, the intermediate shaft bearings 34 and 35 that rotatably support the intermediate shaft 40, particularly the bearings that transmit the resultant force, The right-side intermediate shaft bearing 35, which is close to the third intermediate shaft reduction gear 38 that meshes with the first crankshaft-side reduction gear 36, receives a large reaction force, so a large one that can support a large force must be used, which results in an increase in the size of the drive unit 20 (particularly in this embodiment, the width direction dimension of the portion where the intermediate shaft 40 of the drive unit 20 is arranged becomes large).

[0062] In this way, when the drive unit 20 becomes larger and the width dimension of the drive unit 20 increases, the distance L1 (see Figure 2) between the left and right crank arms 7b becomes significantly larger than that of a general bicycle (e.g., a so-called sports bicycle), which creates the drawback that it becomes difficult to achieve the same functions as a general bicycle (e.g., a so-called sports bicycle).

[0063] To address these difficulties, in drive unit 20 of an electrically assisted bicycle according to a third embodiment of the present invention shown in Figures 14 to 16, rotating shaft 21a of motor 21, intermediate shaft 40, and crankshaft 7a are arranged from the front (this arrangement is the same as in the above-described embodiments), but unlike the above-described embodiments, intermediate shaft 40 is arranged above the line connecting crankshaft 7a and motor shaft 21a. In this case, as shown in Figure 15, when drive unit 20 is viewed from the right side facing the direction of travel, crankshaft 7a, motor shaft 21a, and intermediate shaft 40 are arranged so that the angle α between line A connecting the axis of crankshaft 7a and the axis of motor shaft 21a and the line connecting the axis of crankshaft 7a and the axis of intermediate shaft 40 is within a range of 30 to 70 degrees in the clockwise direction.

[0064] The drive unit 20 of the electrically assisted bicycle according to this third embodiment differs from the drive unit 20 according to the first embodiment mainly in the arrangement of the intermediate shaft 40, crankshaft 7a, and motor shaft 21a and the structure (size, etc.) of the bearings associated with this arrangement, but the other configurations are the same as those of the drive unit 20 according to the first embodiment. That is, the second and third intermediate shaft reduction gears 37, 38 attached to the intermediate shaft 40, the motor shaft reduction gear 39 attached to the motor shaft 21a, and the first reduction gear (crankshaft side reduction gear) 36 arranged on the outer periphery of the crankshaft 7a are all helical (helical tooth) gears, as shown in FIG. 11, to reduce noise. Furthermore, when the motor 21 is driven and an auxiliary driving force is output, the motor shaft 21a and the motor shaft reduction gear 39 rotate clockwise (right) when viewed from the right side, the second intermediate shaft reduction gear 37 meshing with the motor shaft reduction gear 39, the intermediate shaft 40 and the third intermediate shaft reduction gear 38 rotate counterclockwise (left) when viewed from the right side, and the first crankshaft side reduction gear 36 meshing with the third intermediate shaft reduction gear 38 rotates clockwise (right) when viewed from the right side.

[0065] In this configuration, as shown in Fig. 15, when the reduction gears 36 to 39 of the reduction mechanism 25 mesh with each other, force vectors (reaction forces) V11 to P16 are generated, which act on the intermediate shaft 40 as shown in Fig. 16. Note that Fig. 15 shows the force vectors (reaction forces) acting on the contact portions of the gears (force vectors (reaction forces) that ultimately relate to the intermediate shaft 40), and Fig. 16 shows a state in which the force vectors (reaction forces) act on the intermediate shaft 40 (a state in which the force vectors are concentrated at the axis of the intermediate shaft 40).

[0066] 15 and 16, V11 is a tangential force vector on the intermediate shaft bearing 35 due to the meshing of the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, V12 is a separating force vector on the intermediate shaft bearing 35 due to the meshing of the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, and V13 is a load vector due to a thrust force on the intermediate shaft bearing 35 due to the meshing of the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37. Also, V14 is a tangential force vector on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, V15 is a separating force vector on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, and V16 is a load vector due to a thrust force on the intermediate shaft bearing 35 due to the meshing of the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38. P17 is a load vector due to the thrust force on the intermediate shaft bearing 35 caused by the meshing of the reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, and P17 is a reaction force (resultant force) vector acting (combined) on the intermediate shaft 40.

[0067] According to the above-described arrangement, the forces V11 to P16 acting on the intermediate shaft 40 when the reduction gears 36 to 39 mesh with each other cancel each other out, ultimately reducing the reaction force (resultant force) P17 acting on the intermediate shaft. This allows the use of a small intermediate shaft bearing 35 (one that is small in the width direction or radial direction) that can support a relatively small load, thereby enabling the drive unit 20 to be made smaller (for example, the drive unit 20 can be made smaller in the width direction, etc.). As a result, the distance L2 between the crank arms can be made closer to the distance between the crank arms of a typical bicycle (for example, a so-called sports bicycle).

[0068] In this embodiment, the drive sprocket 13 has a shape in which the center bulges to the right, but by using a small intermediate shaft bearing 35, the intermediate shaft bearing 35 and the portion of the first case 22a that holds the intermediate shaft bearing 35 can be positioned so that they fit into the bulging portion of the drive sprocket 13, making it possible to further miniaturize the drive unit 20 (for example, miniaturizing the drive unit 20 in the width direction, etc.). As a result, the distance L2 between the crank arms can be made closer to that of a typical bicycle (for example, a so-called sports bicycle).

[0069] In the drive unit 20 of the electrically assisted bicycle according to the third embodiment, when the motor shaft (rotating shaft of the motor 21) 21a is located forward of the crankshaft 7a, the intermediate shaft 40 is located below the line connecting the crankshaft 7a and the motor shaft 21a. However, this is not the only possible case. That is, as shown in Fig. 17, when the motor shaft 21a is located rearward of the crankshaft 7a, the intermediate shaft 40 may be configured to be located above the line connecting the crankshaft 7a and the motor shaft 21a.

[0070] Furthermore, in either case, such as when the intermediate shaft 40 is disposed to the right or left of the straight line connecting the crankshaft 7a and the motor shaft 21a, it is preferable to dispose the crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 so that, when the drive unit 20 is viewed from the side from the right side facing the direction of travel, the angle at which the line connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a intersects with the line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 is within a range of 30 degrees to 70 degrees in the clockwise direction.

[0071] Furthermore, similar effects can be obtained by applying a similar arrangement to a drive unit 20 that incorporates a gear change mechanism, such as the drive unit 20 of the electrically assisted bicycle according to the second embodiment. [Industrial Applicability]

[0072] The present invention is applicable to drive units for various electrically assisted bicycles that can travel by adding auxiliary driving force generated by a motor to the human driving force from the pedals, and to such electrically assisted bicycles. [Explanation of symbols]

[0073] 1. Electrically assisted bicycle 7a Crankshaft 8 pedals 10 Rotation detector (rotation sensor) 11 Rotation detection element 20 Drive unit 21 Motor 21a Rotation axis 21b Stator 24 Substrate (first substrate) 24A Auxiliary board for crankshaft rotation sensor (second board) 24B Auxiliary board for motor rotation detection (third board) 25, 25A reduction mechanism 29 Resultant force transmission body 36 First reduction gear 37 Second intermediate shaft reduction gear (intermediate shaft reduction gear) 39 Motor shaft reduction gear 40 Intermediate shaft 42 One-way clutch 43 Motor rotation sensor

Claims

1. A drive unit for an electrically assisted bicycle, which is attached to an electrically assisted bicycle and can travel by adding auxiliary driving force from a motor to human driving force from pedals, and which includes the motor, The electrically assisted bicycle has a mounting portion that is attached to a midpoint between the front wheel and the rear wheel, a crankshaft insertion region through which a crankshaft through which human-powered driving force from the pedals is inserted, and a driving force output wheel that outputs driving force, The crankshaft and the motor are disposed on different axes, A drive unit for an electrically assisted bicycle, characterized in that a substrate is arranged inside the drive unit, and this substrate is arranged so that, when viewed from the side along the crankshaft, it has a portion that overlaps with the stator of the motor.

2. 2. The drive unit for an electrically assisted bicycle according to claim 1, wherein the substrate is arranged so as to overlap with the stator of the motor by an area of at least half of the stator when viewed from the side.

3. 3. The drive unit for an electrically assisted bicycle according to claim 1 or 2, characterized in that, when viewed from the side, the substrate is arranged so as to overlap from the area where the stator of the motor is arranged to the area around the crankshaft.

4. 4. The drive unit for an electrically assisted bicycle according to claim 1, wherein a motor rotation sensor for reading the rotation of the motor is attached to the board.

5. 5. The drive unit for an electrically assisted bicycle according to claim 1, wherein a crankshaft rotation sensor for reading the rotation of the crankshaft is attached to the board.

6. A drive unit for an electric assisted bicycle as described in any one of claims 1 to 3, characterized in that a motor rotation sensor that reads the rotation of the motor and a crankshaft rotation sensor that reads the rotation of the crankshaft are attached to the substrate.

7. A drive unit for an electric assisted bicycle as described in any one of claims 1 to 6, characterized in that multiple substrates are provided, and the substrate having a portion overlapping the stator of the motor is the substrate with the largest area among the multiple substrates.

8. The rotation of the motor is transmitted to a driving force output wheel that outputs a driving force via a two-stage reduction mechanism, 8. The drive unit for an electrically assisted bicycle according to claim 1, wherein a reduction ratio, which is the ratio of the rotation speed of the motor to the rotation speed of the drive force output wheel, is 30 to 37.

9. 9. The drive unit for an electrically assisted bicycle according to claim 1, wherein the minimum radius around the crankshaft is 50 mm or less.

10. a reduction mechanism having a plurality of pairs of reduction gears is provided; the reduction mechanism includes an intermediate shaft disposed parallel to the crankshaft, a plurality of intermediate shaft reduction gears provided on the intermediate shaft, a crankshaft side reduction gear rotatably disposed on the outer periphery of the crankshaft to which the manual drive force and the auxiliary drive force are transmitted, and a motor shaft reduction gear provided on a motor shaft; an intermediate shaft bearing that rotatably supports the intermediate shaft, The intermediate shaft is disposed between the crankshaft and the motor shaft in the front-rear direction, and when the motor shaft is disposed forward of the crankshaft, the intermediate shaft is disposed between the crankshaft and the motor shaft. When the motor shaft is located rearward of the crankshaft, the intermediate shaft is located above the line connecting the crankshaft and the motor shaft. An electrically assisted bicycle comprising the drive unit according to any one of claims 1 to 9.

11. 11. An electrically assisted bicycle equipped with a drive unit according to claim 10, characterized in that the crankshaft, motor shaft, and intermediate shaft are arranged so that, when viewed from the side from the right side facing the direction of travel of the electrically assisted bicycle, the angle at which a line connecting the axis of the crankshaft and the axis of the motor shaft intersects with a line connecting the axis of the crankshaft and the axis of the intermediate shaft is within a range of 30 to 70 degrees in a clockwise direction.

12. A drive power supply device comprising: a drive unit for an electrically assisted bicycle according to any one of claims 1 to 9; and a power storage device for supplying power to the drive unit.

13. An electrically assisted bicycle comprising the drive unit of an electrically assisted bicycle according to any one of claims 1 to 9, or the drive power supply device according to claim 12.

Images