Drive Unit and Electric-Assist 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 attached to an electric assist bicycle that can travel by adding an auxiliary driving force generated by a motor to a human driving force generated by a pedaling force from a pedal, and an electric assist bicycle.

Background Art

[0002] An electric assist bicycle (also referred to as an electric bicycle) having a battery as a power source and a drive unit including a motor powered by the battery, and adding an auxiliary driving force (assist force) of the drive unit to a human driving force generated by a pedaling force applied to a pedal, can travel easily even on an uphill slope or the like and is already widely known.

[0003] In this electric assist bicycle, there is one in which a drive unit incorporating a motor or the like is disposed at a location where a crankshaft is provided. In an electric assist bicycle having such an arrangement configuration, a relatively heavy drive unit is disposed at a low position in the center in the front-rear direction of the electric assist bicycle (that is, in the middle between the front wheel and the rear wheel). Therefore, compared with an electric assist bicycle in which a motor is built in the hub of the front wheel or the hub of the rear wheel, this electric assist bicycle with such an arrangement configuration is easy to lift the front wheel and the rear wheel, and can easily overcome a step on the traveling road. It has the advantages of easy handling of the vehicle body and good running stability.

[0004] The drive unit incorporates a substrate (also referred to as a main substrate or a drive substrate) on which various electronic components for driving or controlling the motor are mounted. Since this substrate mounts large electronic components such as FETs and a relatively large number of electronic components, it has a relatively large area. Further, as shown in Patent Document 1 or the like, this substrate is arranged around the crankshaft in a side view (viewed in the direction of the crankshaft axis).

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2016-203735 Summary of the Invention Problems to be Solved by the Invention

[0006] By the way, in recent years, in an electric assist bicycle, there are cases where a bicycle in which the distance from the crankshaft to the rear wheel or the front wheel is not much different from that of a general bicycle and the functions as a bicycle can be exhibited well is preferred. However, when a drive unit in which a substrate is arranged around the crankshaft is adopted, as the substrate becomes larger, a wider area around the crankshaft is required, and the drive unit also becomes larger. Even if the arrangement of the drive unit is contrived, the distance from the crankshaft to the axle of the rear wheel becomes considerably long, causing a problem.

[0007] The present invention solves the above problems, and aims to provide a drive unit for an electric assist bicycle that can be miniaturized such that the area around the crankshaft can be minimized, and can exhibit good functions as a bicycle, and an electric assist bicycle equipped with this drive unit. Means for Solving the Problems

[0008] In order to solve the above problems, the drive unit of the present invention is attached to an electric assist bicycle that can travel by adding an auxiliary driving force by a motor to a human driving force by a pedaling force from a pedal, and is a drive unit of an electric assist bicycle equipped with the motor, A crankshaft to which the manual driving force from the pedal is transmitted, a driving force output ring body that outputs a driving force, and , a speed reduction mechanism that reduces the rotation of the motor and transmits it to the driving force output wheel body, a first substrate to which a motor rotation sensor for reading the rotation speed of the motor is attached, and a second substrate connected to the first substrate, wherein the crankshaft and the motor are arranged with different axial centers, a motor arrangement region where the motor is arranged and a speed reduction mechanism arrangement region where the speed reduction mechanism is arranged are partitioned by a partition member, and the first substrate and the second substrate are arranged in the speed reduction mechanism arrangement region is characterized in that.

[0009] Note that the rotation shaft of the motor has a motor shaft reduction gear, and the speed reduction mechanism has an intermediate shaft arranged in parallel with the crankshaft and a reduction gear arranged with a different axial center from the intermediate shaft. The intermediate shaft includes a large-diameter intermediate shaft gear that meshes with the motor shaft reduction gear and a small-diameter intermediate shaft gear that meshes with the reduction gear. It is preferable that the first substrate is configured to be arranged between the motor and the reduction gear in the axial direction of the crankshaft.

[0010] Further, the second substrate may be arranged between the motor and the reduction gear in the axial direction of the crankshaft.

[0011] Further, when viewed from the side along the crankshaft, the first substrate and the large-diameter intermediate shaft gear may overlap.

[0012] Further, when viewed from the side along the crankshaft, it is preferable that the first substrate is configured to overlap with the stator of the motor.

[0013] Further, it is preferable that a crankshaft rotation sensor for reading the rotation of the crankshaft is attached to the second substrate.

[0014] Further, the electric assist bicycle of the present invention is characterized by including the drive unit according to any one of the above.

Advantages of the Invention

[0015] According to the present invention, First by arranging the substrate so that the portion overlapping the stator of the motor in a side view has a portion, it is possible to adopt a substrate with a sufficiently large area, and even when arranging the substrate (a separate substrate or a part of the substrate) around the crankshaft, the area of the substrate around the crankshaft can be reduced. As a result, by devising the arrangement of the drive unit, the distance from the crankshaft to the axle of the rear wheel can be made closer to that of a general bicycle. Also, First by arranging the substrate so that the portion overlapping the stator of the motor in a side view has a portion, there is also a so-called sound insulation effect that the sound generated by the motor can be blocked by the substrate.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Embodiments for Carrying Out the Invention

[0017] (First Embodiment) Hereinafter, a drive unit of an electric assist bicycle according to an embodiment of the present invention and an electric assist bicycle to which this drive unit is attached will be described with reference to the drawings. In the following description, the left - right direction and the front - rear direction refer to the directions in the state where a person is riding on the electric assist bicycle 1 in the traveling direction. Also, the configuration of the present invention is not limited to the configuration described below.

[0018] In FIG. 1, reference numeral 1 denotes an electric assist bicycle to which a drive unit according to an embodiment of the present invention is attached. As shown in FIG. 1, this electric assist bicycle 1 includes a metal frame 2 composed of a head pipe 2a, a front fork 2b, an upper pipe 2c, a lower pipe 2g, a vertical pipe 2d, a chain stay 2 e, a seat stay 2f, etc., 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 handle 5 for changing the direction of the front wheel 3, a saddle 6 on which a rider sits, a crank 7 and pedals 8 to which a human - power driving force consisting of pedaling force is applied, an electric motor 21 (also see FIG. 2) as a drive source for generating an auxiliary driving force (assist force), and a control unit for controlling various electrical components including this motor 21, etc., provided with a drive unit (drive unit device) 20, a battery 12 composed of a secondary battery for supplying driving power to the motor 21, a hand operation unit 18 attached to the handle 5, etc., operable by a rider, etc., for setting and changing the power - on / off and traveling mode, etc., of the electric assist bicycle 1, a drive sprocket (also referred to as a front sprocket, a crank sprocket, or a front gear) 13 attached so as to rotate integrally coaxially with the crankshaft 7a and outputting a combined force of the human - power driving force and the auxiliary driving force, a rear sprocket (sometimes also referred to as a rear gear) 14 as a rear wheel body attached to the hub (also referred to as a rear hub) 9 of the rear wheel 4, and a chain 15 as an endless driving - force transmission body wound endlessly in a rotatable state between the drive sprocket 13 and the rear sprocket 14. Also, the drive unit 20 and the battery 12 constitute a drive power supply device (drive unit module).

[0019] The electric assist bicycle 1 can travel by adding the auxiliary driving force generated by the motor 21 to the human power driving force by the pedaling force from the pedal 8, and the resultant force obtained by adding the auxiliary driving force to the human power driving force is transmitted from the drive sprocket 13 to the rear wheel 4 via the chain 15, the rear sprocket 14, and the like.

[0020] Note that the battery 12 is an example of a power storage device, and a secondary battery is preferable, but the power storage device may be a capacitor or the like. The crank 7 includes crank arms 7b provided on the left and right, respectively, and a crankshaft 7a that connects the left and right crank arms 7b, and the pedal 8 is rotatably attached to the end of the crank arm 7b.

[0021] As shown in FIG. 1, in this electric assist bicycle 1, the drive unit 20 is disposed at an intermediate position between the front wheel 3 and the rear wheel 4, more specifically, at a location where the crankshaft 7a passes through. By adopting such an arrangement configuration, the drive unit 20, which is relatively heavy, is disposed at the center in the front-rear direction of the electric assist bicycle 1. As a result, it is easy to lift the front wheel 3 and the rear wheel 4, and even if there is a step on the traveling road, it can be easily overcome. Thus, the handling of the vehicle body (such as the frame 2) of the electric assist bicycle 1 is good, and the traveling stability is also good.

[0022] As shown in Fig. 2, the drive unit 20 has an outer shell portion and the like formed by a unit case 22 composed of first to third cases 22a to 22c, and the crankshaft 7a passes through the drive unit 20 (in this embodiment, the crankshaft insertion region 16 provided at the rear of the drive unit 20) from left to right. Further, the unit case 22 is integrally formed with a mounting portion 22d for mounting the drive unit 20 at an intermediate position between the front wheel and the rear wheel in the electric assist bicycle. Further, on the outer periphery of the crankshaft 7a, there are provided a substantially cylindrical power transmission body 28 to which the manual driving force from the crankshaft 7a is transmitted, an interlocking cylinder body 23 to which the manual driving force from the power transmission body 28 is transmitted, and a resultant force transmission body 29 to which the manual driving force from the interlocking cylinder body 23 is transmitted via a one-way clutch (one-way clutch for cutting off the auxiliary driving force) 30 and the like, and the resultant force obtained by combining the manual driving force and the auxiliary driving force from the motor 21 is transmitted to the drive sprocket 13.

[0023] Further, 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 (in this embodiment, the intermediate shaft 40), and an auxiliary drive A motor 21 is provided as a power (assist power) drive source, and a substrate (also referred to as a drive substrate or a main substrate) 24 on which various electronic components for performing various electrical controls are provided is also provided. A control unit is constituted by the substrate 24 and the electronic components (such as an FET (field effect transistor) 24a, a capacitor, and a microcomputer) mounted on this substrate. As shown in FIGS. 2 and 3, the axis of the rotation shaft 21a of the motor 21, the axis of the crankshaft 7a, and the axis of an intermediate shaft 40 described later are different from each other in position. Further, in this embodiment, the rotation shaft 21a of the motor 21, the intermediate shaft 40, and the crankshaft 7a are arranged in order from the front, and the intermediate shaft 40 is arranged below the straight line connecting the crankshaft 7a and the motor shaft 21a. Further, inside the drive unit 20 (specifically, inside the unit case 22 of the drive unit 20), portions excluding both end portions of the crankshaft 7a, a human power transmission body 28, an interlocking cylinder body 23, a resultant force transmission body 29, a speed reduction mechanism 25, the motor 21, a torque sensor 31 described later, a rotation detection body 11, a rotation detector (rotation sensor) 10, etc. are provided. Then, the human power driving force and the auxiliary driving force are synthesized inside the drive unit 20, and the synthesized resultant force is configured to be output from a drive sprocket 13 provided outside the drive unit 20 (specifically, outside the unit case 22 of the drive unit 20).

[0024] The drive unit 20 will be described in more detail. As shown in FIGS. 2 and 3, the crankshaft 7a is rotatably arranged by bearings (crankshaft bearings) 26 and 27 in a state of penetrating the rear part of the drive unit 20 from left to right. And, on the outer periphery of the left-side portion of this crankshaft 7a, a cylindrical human power transmission body 28 is fitted in a state of rotating integrally with the crankshaft 7a via a serration portion (or spline portion) 7c. Note that a serration portion (or spline portion) 28b is also formed at a location corresponding to the serration portion (or spline portion) 7c of the crankshaft 7a on the inner periphery of the human power transmission body 28 and meshes with the serration portion (or spline portion) 7c of the crankshaft 7a.

[0025] On the outer peripheral surface of the manual transmission body 28, a magnetostrictive generation portion 31b imparted with magnetic anisotropy is formed, and a coil 31a is disposed on the outer periphery thereof with a certain gap (space) therebetween. The magnetostrictive torque sensor (manual force detection portion) 31 is constituted by these magnetostrictive generation portion 31b and coil 31a. Thereby, the manual driving force from the crankshaft 7a is transmitted to the manual transmission body 28, and the manual driving force is detected by the torque sensor 31. Further, in this magnetostrictive torque sensor 31, the magnetostrictive generation portion 31b is formed in a spiral shape forming, for example, +45 degrees and -45 degrees with respect to the axial direction of the manual transmission body 28. When a manual driving force is transmitted to the manual transmission body 28, strain occurs in the magnetostrictive generation portion 31b on the surface of the manual transmission body 28, and an increasing portion and a decreasing portion of the magnetic permeability are generated. Thus, the magnitude of the torque (manual driving force) can be detected by measuring the inductance difference of the coil 31a.

[0026] The interlocking cylinder body 23 is disposed in a rotatable state with respect to the crankshaft 7a at a location adjacent to the right side of the manual transmission body 28 on the outer periphery of the crankshaft 7a. Then, a serration portion (or spline portion) 28a formed on the outer periphery of the right end portion of the manual transmission body 28 and a serration portion (or spline portion) 23a formed on the inner periphery of the left end portion of the interlocking cylinder body 23 are fitted to each other, and the interlocking cylinder body 23 rotates integrally with the manual transmission body 28. In this embodiment, the serration portion (or spline portion) 23a formed on the inner periphery of the left end portion of the interlocking cylinder body 23 is fitted to the serration portion (or spline portion) 28a of the manual transmission body 28 from the outside.

[0027] Further, in this embodiment, a rotation detector 11 for detecting the rotation state of the interlocking cylinder body 23 is attached to the outer periphery of the left side portion of the interlocking cylinder body 23. Further, 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 detector 11 from the outer peripheral side. For example, the rotation detector 10 is configured such that optical sensors having an emission portion and a light receiving portion are arranged in the rotation direction of the rotation detector 11 (not shown (2) The rotation detector 11 has a number of tooth portions on its outer peripheral side that extend to the right in a comb-like shape. When there are tooth portions on the rotation detector 11, the emitted light is reflected and received, and the light incident state and non-incident state are electrically detected by the light receiving portion of the rotation detector 10. Then, the detected signal is input by the control unit to detect the rotation speed (rotation amount) and rotation direction of the interlocking cylinder body 23. Instead of the optical sensor, a magnetic sensor such as a Hall IC may be provided to detect the rotation speed (rotation amount) and rotation direction of the interlocking cylinder body 23. Here, the interlocking cylinder body 23 rotates integrally with the power transmission body 28, and the power transmission body 28 rotates integrally with the crankshaft 7a. Therefore, by detecting the rotation amount and rotation direction of the interlocking cylinder body 23, the rotation speed (rotation amount) and rotation direction of the crankshaft 7a and the pedal 8 can also be detected.

[0028] Also, on the outer periphery of the right side portion of the interlocking cylinder body 23, a resultant force transmission body 29 is disposed via a one-way clutch (a one-way clutch for cutting off the auxiliary driving force) 30. When the pedal 8 is paddled forward, the human power driving force transmitted to the interlocking cylinder body 23 is transmitted to the resultant force transmission body 29 via the one-way clutch 30.

[0029] The motor 21 has its rotating shaft 21a and rotor 21b rotatably supported by motor shaft bearings 32 and 33. Also, the rotating shaft 21a of the motor 21 protrudes to the right side, and a motor shaft reduction gear 39, which will be described later, is formed on the outer periphery of this protruding portion.

[0030] The reduction mechanism 25 includes an intermediate shaft 40 disposed in parallel with the crankshaft 7a and two pairs of reduction gears 36 - 39 including a large-diameter reduction gear (the first reduction gear: the crankshaft-side reduction gear) 36 formed on the leftward portion of the resultant force transmission body 29, and constitutes a two-stage reduction mechanism. Then, the reduction mechanism 25 synthesizes the human power driving force transmitted through the crankshaft 7a and the auxiliary driving force transmitted from the motor 21, and transmits the resultant force formed by the synthesis of the human power driving force and the auxiliary driving force to the resultant force transmission body 29.

[0031] The intermediate shaft 40 extends horizontally at the center in the front-rear direction of the drive unit 20 in a posture 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 cutting off the manual driving force are attached to the intermediate shaft 40.

[0032] The one-way clutch 42 for cutting off the manual driving force is disposed between the outer circumference of the intermediate shaft 40 and the inner circumference of the second intermediate shaft reduction gear 37, and is for cutting off the manual driving force from the pedal 8. That is, when the motor 21 is not driven and no auxiliary driving force is generated, the manual driving force from the pedal 8 is cut off by the one-way clutch 42 for cutting off 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 and 38 rotate integrally with the intermediate shaft 40.

[0033] Since the small-diameter motor shaft reduction gear 39 formed on the rotary shaft 21a of the motor 21 meshes with the large-diameter second intermediate shaft reduction gear 37, when the motor 21 is rotated and an auxiliary driving force is output, the rotation of the motor 21 is decelerated, and the torque of the auxiliary driving force from the motor 21 is amplified and transmitted to the intermediate shaft 40 side. Further, since the small-diameter third intermediate shaft reduction gear 38 meshes with the large-diameter first reduction gear 36 integrally formed on the resultant force transmission body 29, the torque of the auxiliary driving force transmitted to the intermediate shaft 40 is further amplified and transmitted to the first reduction gear 36. Then, in the resultant force transmission body 29 in which the first reduction gear 36 is integrally formed, the manual driving force and the auxiliary driving force from the motor 21 are combined and output from the drive sprocket 13 as a driving force output ring body. 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). Also, the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 is set to 50 mm or less.

[0034] Also, in this embodiment, inside the unit case 22 of the drive unit 20, only one large-area substrate 24 is provided as the substrate. And when this substrate 24 is viewed from the side along the crankshaft 7a (when viewed from the side along the axial direction of the crankshaft 7a), as shown in FIG. 3, it is arranged so as to have a portion overlapping with the stator of the motor 21 (more specifically, the region where the stator core in the stator of the motor 21 is provided) 21c. Further, in this embodiment, this 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, this substrate 24 is arranged so as to overlap from the region where the stator 21c of the motor 21 is arranged to the region around the crankshaft 7a.

[0035] Also, in this embodiment, the substrate 24 is also provided in a region overlapping with the rotor 21b of the motor 21 when viewed from the side, as shown in FIG. 3. And this 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 a region overlapping with the motor 21 (the entire motor) when viewed from the side, as shown in FIG. 3, and this substrate 24 is arranged so as to overlap with more than half of the area of the motor 21.

[0036] Further, in this embodiment, as shown in FIG. 3 in side view, the substrate 24 is also provided in a region where the first reduction gear 36 and the stator 21c of the motor 21 do not overlap. Also, as shown in FIG. 2 in plan view (or front view), the substrate 24 is provided between the motor 21, the first reduction gear 36, the resultant force transmission body 29, and the interlocking cylinder body 23. Further, when viewed from the front (when viewed along the front-rear direction), the substrate 24 is provided in a region that overlaps with the manual transmission body 28, as schematically shown in FIG. 2. Note that in this embodiment, as shown in FIG. 3 in side view, the substrate 24 is provided in a region that does not overlap with the second reduction gear 37. Also, when viewed from the front (when viewed along the front-rear direction), the substrate 24 is provided in a region that does not overlap with the second reduction gear 37, as schematically shown in FIG. 2. However, the present invention is not limited to this, and when the substrate 24 is viewed from the side, it may be provided so as to partially overlap with the second reduction gear 37.

[0037] Further, in this embodiment, a rotation detector (rotation sensor) 10 (more specifically, a connecting leg portion of the rotation detector (rotation sensor) 10) serving as a crankshaft rotation sensor for reading the rotation of the crankshaft is attached to the substrate 24. Note that in this embodiment, as shown in FIG. 2 in plan view, the substrate 24 is provided between the rotation detection body 11, the rotation detector (rotation sensor) 10, 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.

[0038] Further, in this embodiment, a plurality of magnets are arranged in the circumferential direction on the rotor 21b of the motor 21 such that the magnetic poles of adjacent magnets are different, and a substantially cylindrical magnetic imparting member 21d having the same magnetic poles as these magnetic poles is arranged. The outer peripheral portion of the magnetic imparting member 21d is shaped to protrude to the right, and a motor rotation sensor 43 for reading the rotation of the motor 21 is arranged so as to face the end portion 21da of the protruding magnetic imparting member 21d. Then, this motor rotation sensor 43 is attached to the substrate 24.

[0039] Note that only the end portion 21da of the magnetic member 21d may be magnetized in the same manner as the arrangement of the rotor 21b of the motor 21. Further, in this embodiment, the magnetic member 21d also serves as a partition member that partitions the region (reduction mechanism arrangement region) where the reduction mechanism 25 having a plurality of reduction gears 36 to 39 and the like is arranged and the region (motor arrangement region) where the motor 21 is arranged. Although grease or the like for reducing the friction between the reduction gears 36 to 39 is designed not to enter the motor 21 side, it is not limited thereto. Also, 21ca in FIG. 2 is a connection wire for energizing the coil of the stator 21c. In the above configuration, when the pedal 8 is depressed during forward travel, the manual driving force based on the depressing force applied to the pedal 8 is transmitted from the crankshaft 7a to the manual transmission body 28, the interlocking cylinder body 23, and the resultant force body 29, and the manual driving force is detected by the torque sensor 31 provided on the manual transmission body 28. Then, the auxiliary driving force corresponding to the manual driving force is transmitted to the resultant force transmission body 29 via the reduction gear 36 or the like of the reduction mechanism 25, and the resultant force combined by the resultant force transmission body 29 is transmitted from the drive sprocket 13 to the rear wheel 4 via the chain 15. Thereby, by adding the auxiliary driving force (assist force) of the motor 21 corresponding to the manual driving force, it is possible to travel easily even on an uphill or the like.

[0040]

[0041] Further, according to the above configuration, since the substrate 24 is arranged so as to have a portion overlapping the stator 21c of the motor 21 when viewed from the side, a substrate 24 having a sufficiently large area can be adopted. Also, even when the substrate 24 is arranged around the crankshaft 7a as in this embodiment, the area of the region around the crankshaft 7a in the substrate 24 can be suppressed to be small. Therefore, by devising the arrangement of the drive unit 21 (for example, arranging the motor 21 in front 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 type bicycle).

[0042] ​Further, as described above, by arranging the substrate 24 so as to overlap with more than half of the area of the stator 21c of the motor 21 in a side view, the area of the region around the crankshaft 7a on the substrate 24 can be minimized. Therefore, the distance from the crankshaft 7a to the axle of the rear wheel 4 of the electric assist bicycle 1 can be made closer to that of a general bicycle (for example, a so-called sports bicycle). Also, by arranging the substrate 24 so as to have a portion overlapping with the stator 21c of the motor 21 in a side view, the sound generated by the motor 21 can be blocked by the substrate 24. That is, by arranging the substrate 24 so as to overlap with more than half of the area of the stator 21c of the motor 21 as described above, the sound insulation effect can be further enhanced.

[0043] Further, in the above embodiment, a motor rotation sensor 43 for reading the rotation of the motor 21 and a rotation detector 10 as a crankshaft rotation sensor for reading the rotation of the crankshaft 7a are attached to the substrate 24. With this configuration, the number of parts of the substrate 24 itself in the drive unit 20 can be made only one, and it is possible to reduce the number of parts and the labor of attaching the substrate. And in the present invention, as schematically shown in FIG. 2, the substrate 24 is provided between the motor 21, the first reduction gear 36, the resultant force transmission body 29, and the interlocking cylinder body 23 in a plan view (or a front view). Therefore, there is an advantage that it is easy to attach the motor rotation sensor 43 and the rotation detector 10 as a crankshaft rotation sensor to the substrate 24. Also, as shown in FIG. 2, in a side view, the substrate 24 is provided so as to overlap with the rotor 21b and the magnetic member 21d of the motor 21. Therefore, there is also an advantage that it is easy to attach the motor rotation sensor 43 to the substrate 24.

[0044] However, it is not limited to this. As shown in FIG. 4, an auxiliary substrate 24A for a crankshaft rotation sensor to which the rotation detector 10 as a crankshaft rotation sensor is attached may be provided separately from the substrate (main substrate) 24, and this auxiliary substrate 24A for a crankshaft rotation sensor may be configured to be connected to the substrate (main substrate) 24 (the first modification of the first embodiment). Also, as shown in FIG. 5, an auxiliary substrate 24B for motor rotation detection to which the motor rotation sensor 43 is attached is the substrate ( The auxiliary substrate 24B for motor rotation detection may be provided separately from the main substrate 24 and configured to be connected to the substrate (main substrate) 24 (the second modification of the first embodiment). In this embodiment, as shown in FIGS. 4 and 5, in a plan view, the substrate (main substrate) 24 is provided between the rotation detector 11, the rotation detector (rotation sensor) 10, the bearing 26 that supports the crankshaft 7a, etc. (the bearing 26 on the side opposite to the side where the drive sprocket 13 is provided on the crankshaft 7a), and the torque sensor 31. In these cases as well, it is preferable that the substrate (main substrate) 24 is larger (has a larger area) than the auxiliary substrate 24A for crankshaft rotation sensor and the auxiliary substrate 24B for motor rotation detection.

[0045] Further, the rotation of the motor 21 is configured to be transmitted to the drive sprocket 13 as a driving force output ring body via the two-stage reduction mechanism 25, and 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 configured to be 30 to 37. As a result, a relatively small-diameter first reduction gear 36 that is coaxial with the crankshaft 7a can be used. As a result, it becomes possible to reduce the diameter (radius and diameter) around the crankshaft 7a in the drive unit 20, and thus, by devising the arrangement of the drive unit 21 (for example, arranging the motor 21 in front 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-type bicycle).

[0046] Further, by setting the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 to 50 mm or less, it becomes possible to further reduce the distance from the crankshaft 7a to the axle of the rear wheel 4 to be closer to that of a general bicycle (for example, a so-called sports-type bicycle). And by setting the minimum radius around the crankshaft 7a (around the crankshaft) of the drive unit 20 to 45 mm or less, it becomes possible to further reduce the distance from the crankshaft 7a to the axle of the rear wheel 4 to be closer to that of a general bicycle (for example, a so-called sports-type bicycle).

[0047] (Second Embodiment) In the above embodiment, the case where the reduction ratio of the speed reduction mechanism 25 is constant has been described. However, the present invention is not limited thereto, and a speed reduction mechanism 25A having a shift function capable of selecting and switching a plurality of reduction ratios (two shift stages in this embodiment) may be provided in the drive unit 20.

[0048] As shown in FIGS. 6 to 10, the speed reduction mechanism 25A provided in the drive unit 20 according to this embodiment has a plurality of selectable shift stages (two shift stages of a low speed stage and a high speed stage in this embodiment) with different gear ratios on the outer peripheral side and the right side of the interlocking cylinder 23, and transmits the driving force to the resultant force transmission body 29 via a one-way clutch (one-way clutch for cutting off the auxiliary driving force) 30.

[0049] The speed reduction mechanism 25A includes a rotation transmission cylinder 49 that is rotatably disposed on the outer periphery of the crankshaft 7a and transmits the rotation of the interlocking cylinder 23 via a one-way clutch (one-way clutch for cutting off the auxiliary driving force) 30, a low speed stage transmission gear (also referred to as a crankshaft side low speed stage transmission gear) 36A that extends radially outward from the right cylindrical portion of the rotation transmission cylinder 49 and is integrally formed, a low speed stage clutch 51 that is disposed between the rotation transmission cylinder 49 and the resultant force transmission body 29 and can transmit the driving force of the crankshaft side low speed stage transmission gear 36A to the resultant force transmission body 29, a high speed stage transmission gear (also referred to as a crankshaft side high speed stage transmission gear) 36B 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 an intermediate shaft side low speed stage transmission gear) 38A that is integrally formed on the intermediate shaft 40 and meshes with the crankshaft side low speed stage transmission gear 36A, an intermediate shaft tooth portion 40a that is integrally formed on the intermediate shaft 40 and meshes 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, and a high speed stage clutch 55 that is provided on the outer periphery and the right side region of the intermediate shaft tooth portion 40a of the intermediate shaft 40 and can transmit the resultant force from the intermediate shaft 40 to the crankshaft side high speed stage transmission gear 36B and the resultant force transmission body 29. This high speed stage clutch 55 (specifically It is composed of engaging claws that can extend and retract from the main body 55a of the high-speed clutch 55 to the outer peripheral side, and has a high-speed gear part (the high-speed gear part on the intermediate shaft side, which is the engaging claw part of the so-called high-speed clutch 55) 38B that can be engaged and disengaged with the high-speed transmission gear 36B on the crankshaft side (see FIGS. 9 and 10). A shift stage switching body 61 that can be engaged and disengaged from the outer peripheral side of the right side part of the high-speed gear part 38B on the intermediate shaft side and is moved according to the selected shift stage, and a shift movement arm 62 that engages with the shift stage switching body 61 and moves the shift stage switching body 61 in the crankshaft direction are provided.

[0050] When the pedal 8 is paddled forward, the human power driving force transmitted to the interlocking cylinder body 23 is transmitted to the rotary transmission cylinder 49. In this embodiment, the high-speed clutch 55 is disposed on the outer peripheral side of the intermediate shaft 40 so as to be movable in the same axial direction as the axis of the intermediate shaft 40.

[0051] Here, the low-speed transmission gear 36A on the crankshaft side has a larger diameter than the high-speed transmission gear 36B on the crankshaft side, and the low-speed transmission gear 38A on the intermediate shaft side has a smaller diameter than the high-speed gear part 38B on the intermediate shaft side. As a result, the rotational force of the intermediate shaft 40 is transmitted to the low-speed transmission gear 36B on the crankshaft side and the rotary transmission cylinder 49 at a low speed, and is transmitted to the high-speed transmission gear 36B on the crankshaft side at a high speed.

[0052] The shift movement arm 62 is preferably driven by an electric transmission device 51 (schematically shown in FIG. 7) provided inside (or outside) the drive unit 20. For example, it is preferable to provide a shift stage switching switch on the hand operation unit 18 to configure the shift stage to be switchable. However, it is not limited to this, and the shift movement arm (the shift part moved via a wire or the like) 62 may be provided near the handle.

[0053] When the low-speed stage is selected, as shown in FIGS. 6 and 8, the shift stage switching body 61 is moved to a position closer to the left by the shift movement arm 62, and the intermediate shaft side high-speed stage shift gear part 38B, which consists of an engaging claw that can be retracted and extended from the high-speed stage clutch 55, is tilted and separated from the crankshaft side high-speed stage shift gear 36B. Therefore, the human power driving force transmitted from the interlocking cylinder body 23 side via the one-way clutch (one-way clutch for cutting off 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 shift gear 38A are transmitted to the rotation transmission cylinder 49 in a relatively low rotation state and combined, and this rotational driving force (resultant force) is output from the drive sprocket 13 via the low-speed stage clutch 51 and the resultant force transmission body 29.

[0054] When the high-speed stage is selected, as shown in FIGS. 9 and 10, the shift stage switching body 61 is moved to a position closer to the right by the shift movement arm 62, and the claw part that can engage with the crankshaft side high-speed stage shift gear 36B (specifically, the tooth part of the crankshaft side high-speed stage shift gear 36B) of the high-speed stage clutch 55 is made to be able to stand up, and the rotation of the crankshaft side high-speed stage shift gear 36B can be transmitted to the resultant force transmission body 29. Therefore, the human power driving force transmitted from the interlocking cylinder body 23 side via the one-way clutch (one-way clutch for cutting off the auxiliary driving force) 30 is transmitted to the intermediate shaft 40 via the crankshaft side low-speed stage shift gear 36A and the intermediate shaft side low-speed stage shift gear 38A, and the auxiliary driving force is combined to form a resultant force. Then, this resultant force is transmitted to the resultant force transmission body 29 via the intermediate shaft side high-speed stage shift gear 38B and the crankshaft side high-speed stage shift gear 36B in a relatively high rotation state via the high-speed stage clutch 55 and 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 cylinder 49, the low-speed stage clutch 51 is idling.

[0055] Thus, by using this drive unit 20, it is also possible to switch the gear stage within the drive unit 20. Also, in this embodiment as well, by providing the substrate 24 and the like in the same arrangement as in the above-described embodiment, the same operational effects can be obtained. Further, the reduction ratio, which is the ratio of the rotational speed of the motor 21 to the rotational speed of the drive sprocket 13 in the low-speed stage, is 30 to 37 and by configuring such that the reduction ratio in the high-speed stage is less than this, a relatively small-diameter crankshaft-side low-speed stage transmission gear 36A (and crankshaft-side high-speed stage transmission gear 36B), which is coaxial with the crankshaft 7a, can be used, and the same operational effects can be obtained.

[0056] Note that in the above-described embodiment, the case where the high-speed stage clutch 55 is provided on the outer periphery of the intermediate shaft 40 has been described, but it is not limited thereto, and it may be provided in the outer peripheral region of the crankshaft 7a. Also, similar to the above-described embodiment, an auxiliary substrate 24A for the crankshaft rotation sensor for attaching the rotation detector 10 as the crankshaft rotation sensor may be provided separately from the substrate (main substrate) 24, and this auxiliary substrate 24A for the crankshaft rotation sensor may be configured to be connected to the substrate (main substrate) 24. Further, an auxiliary substrate 24B for motor rotation detection for attaching the motor rotation sensor 43 may be provided separately from the substrate (main substrate) 24, and the auxiliary substrate 24B for motor rotation detection may be configured to be connected to the substrate (main substrate) 24.

[0057] In the above-described embodiments (the first and second embodiments), the motor shaft (the rotation shaft 21a of the motor 21) is disposed forward of the crankshaft 7a, and the intermediate shaft 40 is disposed below the straight line connecting the crankshaft 7a and the motor shaft 21a. Note that 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 gears as shown in FIG. 11, and noise reduction is achieved. Note that FIG. 11 corresponds to the first embodiment. Further, when the motor 21 is driven to output an auxiliary driving force, the motor shaft 21a and the motor shaft reduction gear 39 are rotated clockwise (rightward) when viewed from the right side, the second intermediate shaft reduction gear 37 meshing with the motor shaft reduction gear 39, and the intermediate shaft 40 and the third intermediate shaft reduction gear 38 are rotated counterclockwise (leftward) when viewed from the right side, and the first crankshaft-side reduction gear 36 meshing with the third intermediate shaft reduction gear 38 is rotated clockwise (rightward) when viewed from the right side.

[0058] In such a configuration, as shown in FIG. 12, when the reduction gears 36 to 39 of the speed reduction mechanism 25 mesh with each other, force vectors (reaction forces) V1 to P6 are generated and 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 (the force vectors (reaction forces) finally related to the intermediate shaft 40), and FIG. 13 shows the state in which the force vectors (reaction forces) act on the intermediate shaft 40 (the state in which the force vectors are concentrated on the axis of the intermediate shaft 40).

[0059] In FIGS. 12 and 13, V1 is the tangential force vector to the intermediate shaft bearing 35 due to the engagement between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, V2 is the separating force vector to the intermediate shaft bearing 35 due to the engagement between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37, and V3 is the load vector due to the thrust force to the intermediate shaft bearing 35 due to the engagement between the motor shaft reduction gear 39 and the second intermediate shaft reduction gear 37. Further, V4 is the tangential force vector to the intermediate shaft bearing 35 due to the engagement between the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, V5 is the separating force vector to the intermediate shaft bearing 35 due to the engagement between the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, V6 is the load vector due to the thrust force to the intermediate shaft bearing 35 due to the engagement between the first reduction gear (crankshaft side reduction gear) 36 and the third intermediate shaft reduction gear 38, and V7 is the reaction force (resultant force) vector acting on the intermediate shaft 40 (the combined one).

[0060] According to the above arrangement configuration, since the force vectors V1 to P6 to the intermediate shaft 40 generated when the reduction gears 36 to 39 mesh with each other rarely cancel each other out, a relatively large force vector V7 acts on the intermediate shaft 40 in a state where 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 right intermediate shaft bearing 35 close to the third intermediate shaft reduction gear 38 that meshes with the first crankshaft side reduction gear 36 for transmitting the resultant force, receives a large reaction force, so a large-sized one that can support a large force is used. As a result, the drive unit 20 becomes large-sized (particularly in this embodiment, the width direction dimension of the portion where the intermediate shaft 40 of the drive unit 20 is disposed becomes large). In this way, when the drive unit 20 becomes large-sized and the width direction dimension of the drive unit 20 becomes large, the distance L1 (see FIG. 2) between the left and right crank arms 7b increases significantly compared to a general bicycle (for example, a so-called sports type bicycle). Therefore, there is a drawback that it becomes difficult to approach the function as a general bicycle (for example, a so-called sports type bicycle).

[0061]

[0062] To address such problems, in the drive unit 20 of the electric assist bicycle according to the third embodiment of the present invention shown in FIGS. 14 to 16, the rotary shaft 21a of the motor 21, the intermediate shaft 40, and the crankshaft 7a are arranged in order from the front (this arrangement is the same as that of the above embodiment). However, different from the above embodiment, the intermediate shaft 40 is arranged above the straight line connecting the crankshaft 7a and the motor shaft 21a. Further, in this case, as shown in FIG. 15, when the drive unit 20 is viewed from the side on the right side facing the traveling direction, the angle α at which the line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 intersects with the line A connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is within 30 degrees to 70 degrees in the clockwise direction. The crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are arranged accordingly.

[0063] Note that the drive unit 20 of the electric assist bicycle according to this third embodiment is mainly different from the drive unit 20 according to the first embodiment in the arrangement of the intermediate shaft 40, the crankshaft 7a, and the motor shaft 21a, and the structure (such as size) of the bearings associated with this arrangement. 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 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 arranged on the outer periphery of the crankshaft 7a are all helical gears as shown in FIG. 11, and noise reduction is achieved. Also, when the motor 21 is driven and the auxiliary driving force is output, the motor shaft 21a and the motor shaft reduction gear 39 are rotated clockwise (rightward) 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 are rotated counterclockwise (leftward) when viewed from the right side, and the first crankshaft side reduction gear 36 meshing with the third intermediate shaft reduction gear 38 is rotated clockwise (rightward) when viewed from the right side.

[0064] In such a 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 and 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 portion of the gears (the force vectors (reaction forces) ultimately related to the intermediate shaft 40), and FIG. 16 shows the state in which the force vectors (reaction forces) act on the intermediate shaft 40 (the state in which the force vectors are concentrated on the axis of the intermediate shaft 40).

[0065] In FIGS. 15 and 16, V11 is the tangential force vector to 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 the separating force vector to 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 the load vector due to the thrust force to 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 the tangential force vector to 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 the separating force vector to 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 the load vector due to the thrust force to 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 P17 is the reaction force (resultant force) vector acting on the intermediate shaft 40 (the combined one).

[0066] According to the above arrangement configuration, V11 to P16 acting on the intermediate shaft 40 generated when the reduction gears 36 to 39 mesh with each other cancel each other out, and finally, the reaction force (resultant force) P17 acting on the intermediate shaft becomes small. Therefore, as the intermediate shaft bearing 35, a small-sized one (miniaturized in the width direction and the radial direction) that can support a relatively small load can be adopted, and as a result, the drive unit 20 can be miniaturized (for example, the drive unit 20 can be miniaturized in the width direction or the like). As a result, the distance L2 between the crank arms can be made close to the distance between the crank arms of a general bicycle (for example, a so-called sports type bicycle).

[0067] Also, in this embodiment, as the drive sprocket 13, one with a shape that bulges to the right on the central side is used. By using a small intermediate shaft bearing 35, the bulging portion of the drive sprocket 13 can be arranged so that the intermediate shaft bearing 35 and the portion for holding the intermediate shaft bearing 35 in the first case 22a can be inserted, and the drive unit 20 can be made smaller (for example, the drive unit 20 can be made smaller in the width direction or the like). As a result, the distance L2 between the crank arms can be made closer to that of a general bicycle (for example, a so-called sports-type bicycle).

[0068] In addition, in the drive unit 20 of the electric assist bicycle according to the third embodiment, when the motor shaft (rotation shaft of the motor 21) 21a is arranged in front of the crankshaft 7a, the case where the intermediate shaft 40 is arranged below the straight line connecting the crankshaft 7a and the motor shaft 21a has been described, but it is not limited to this. That is, as shown in FIG. 17, when the motor shaft 21a is arranged behind the crankshaft 7a, the intermediate shaft 40 may be configured to be arranged above the straight line connecting the crankshaft 7a and the motor shaft 21a.

[0069] Also, in any case, such as when the intermediate shaft 40 is arranged on the right side or the left side of the straight line connecting the crankshaft 7a and the motor shaft 21a, when the drive unit 20 is viewed from the side from the right side facing the traveling direction, the intersection angle of the line connecting the axis of the crankshaft 7a and the axis of the intermediate shaft 40 with respect to the line connecting the axis of the crankshaft 7a and the axis of the motor shaft 21a is preferably within 30 degrees to 70 degrees in the clockwise direction, and the crankshaft 7a, the motor shaft 21a, and the intermediate shaft 40 are arranged.

[0070] Also, in a drive unit 20 incorporating a transmission mechanism, such as the drive unit 20 of the electric assist bicycle according to the second embodiment, by applying a similar arrangement configuration, similar operational effects can be obtained.

Industrial Applicability

[0071] The present invention is applicable to a drive unit for various electric assist bicycles that can travel by adding auxiliary driving force generated by a motor to the human driving force from a pedal, and to such electric assist bicycles.

Explanation of reference numerals

[0072] 1 Electric assist bicycle 2 Frame 3 Front wheel 4 Rear wheel 5 Handlebar 7 Crank 8 Pedal 10 Rotation detector (crankshaft rotation sensor) 11 Rotation detecting body 12 Battery (electric storage device) 13 Drive sprocket (driving force output wheel body) 14 Rear sprocket 15 Chain (endless driving force transmission body) 20 Drive unit 21 Motor 22 Unit case 23 Interlocking cylinder body 24 Substrate 25, 25A Reduction mechanism 28 Human power transmission body 29 Resultant force transmission body 30 One-way clutch (one-way clutch for cutting off auxiliary driving force) 31 Torque sensor 36 First reduction gear (reduction gear) 36A Low-speed stage shift gear (low-speed stage shift gear on the crankshaft side) 36B High-speed stage shift gear (high-speed stage shift gear on the crankshaft side) 37 Second reduction gear (reduction gear) 38 Third reduction gear (reduction gear) 39 Motor shaft reduction gear 40 Intermediate shaft 42 One-way clutch (one-way clutch for cutting off human driving force) 43 Motor rotation sensor 49 Rotation transmission cylinder 38A Low-speed stage transmission gear (low-speed stage transmission gear on the intermediate shaft side) 38B High-speed stage transmission gear part (high-speed stage transmission gear part on the intermediate shaft side) 61 Transmission stage switching body 62 Transmission movement arm

Claims

1. 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 a human driving force from pedaling force, comprising: A crankshaft to which human driving force from the pedal is transmitted; A driving force output wheel that outputs a driving force; a reduction mechanism that reduces the rotation speed of the motor and transmits the reduced rotation speed to the driving force output wheel; a first substrate on which a motor rotation sensor for reading the number of rotations of the motor is attached; a second substrate connected to the first substrate, The crankshaft and the motor are disposed on different axes, a motor arrangement area in which the motor is arranged and a speed reduction mechanism arrangement area in which the speed reduction mechanism is arranged are separated by a partition member, the first substrate and the second substrate are disposed in the reduction mechanism arrangement area; Drive unit.

2. The rotating shaft of the motor has a motor shaft reduction gear, the reduction mechanism includes an intermediate shaft disposed parallel to the crankshaft and a reduction gear disposed on an axis different from that of the intermediate shaft, the intermediate shaft includes a large-diameter intermediate shaft gear that meshes with the motor shaft reduction gear, and a small-diameter intermediate shaft gear that meshes with the reduction gear, the first base plate is disposed between the motor and the reduction gear in the axial direction of the crankshaft; 2. A drive unit according to claim 1.

3. The second substrate is disposed between the motor and the reduction gear in the axial direction of the crankshaft. A drive unit according to claim 2.

4. When viewed from the side along the crankshaft, The first base plate and the large diameter intermediate shaft gear overlap each other. A drive unit according to claim 2 or 3.

5. When viewed from the side along the crankshaft, the first substrate overlaps with a stator of the motor; A drive unit according to any one of claims 1 to 4.

6. A drive unit described in any one of claims 1 to 5, wherein a crankshaft rotation sensor that reads the rotation of the crankshaft is attached to the second board.

7. An electrically assisted bicycle having a drive unit described in any one of claims 1 to 6.

Images