WO2022162891A1

WO2022162891A1 - Drive unit and electric bicycle

Info

Publication number: WO2022162891A1
Application number: PCT/JP2021/003341
Authority: WO
Inventors: 秀樹田村; 佑介丹治
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2022-08-04

Abstract

The purpose of this invention is to provide a drive unit capable of improving an appearance of an electric bicycle and an electric bicycle having the improved appearance. A drive unit (4) according to this invention comprises a motor (43) which generates a driving force for moving forward an electric bicycle (1) and a drive circuit (42) which drives the motor (43). The motor (43) and the drive circuit (42) are arranged in a down tube (23) so as to be fit within a projection area of a cross section of the down tube (23), the down tube (23) connecting a head tube (21) and a bottom bracket shell (27) of the electric bicycle (1) with each other.

Description

drive unit and electric bicycle

The present disclosure generally relates to drive units and electric bicycles. More particularly, the present disclosure relates to drive units for electric bicycles and electric bicycles comprising such drive units.

The electric bicycle disclosed in Patent Document 1 has two wheels on the front and rear of the frame body. The frame body is composed of a main pipe on the front fork side, a vertical pipe provided upward from the main pipe, and the like, and a saddle on which a user sits is provided at the upper end of the vertical pipe. A power unit having a crankshaft is attached to the lower side of the main pipe, and a pedal is pivotally supported at the tip of a pedal arm attached to the crankshaft. Similarly, a battery unit is mounted below the main pipe and in front of the power unit.

The electric bicycle of Patent Document 1 has a power unit (driving unit) attached to the lower side of the main pipe, and the power unit spoils the appearance of the electric bicycle.

JP-A-9-2368

The present disclosure has been made in view of the above reasons, and its purpose is to provide a drive unit capable of improving the appearance of an electric bicycle, and an electric bicycle with an improved appearance.

A drive unit according to one aspect of the present disclosure is a drive unit for an electric bicycle, and includes a motor that generates driving force for propelling the electric bicycle, and a drive circuit that drives the motor. The motor and the drive circuit are arranged on a connection member that connects the head tube and the bottom bracket shell of the electric bicycle so as to fit within a projection plane of the cross section of the connection member.

An electric bicycle according to one aspect of the present disclosure includes the drive unit described above and the connection member to which the drive unit is attached.

FIG. 1 is a side view showing an electric bicycle provided with the drive unit of the first embodiment. FIG. FIG. 2 is a perspective view showing the drive unit of the same. FIG. 3 is a circuit diagram of the drive unit of the same. FIG. 4 is a front view showing a portion of the down tube to which the drive unit is mounted. FIG. 5 is a side view showing the mounting structure of the drive unit of Modification 1 of the same. FIG. 6 is a side view showing an electric bicycle provided with the drive unit of the second embodiment. FIG. 7A is a plan view of a drive circuit included in the drive unit as viewed from the first mounting surface side. FIG. 7B is a perspective view of the second mounting surface when the drive circuit of the same is viewed from the first mounting surface side. FIG. 8 is a side view of the drive circuit of the same. FIG. 9 is a cross-sectional view showing a first example of the heat transfer portion of the same. FIG. 10 is a cross-sectional view showing a second example of the heat transfer portion of the same. FIG. 11 is a cross-sectional view showing a third example of the heat transfer portion of the same.

A drive unit and an electric bicycle according to embodiments will be described in detail below with reference to the drawings. However, each drawing described in the following embodiments is a schematic drawing, and the ratio of the size and thickness of each component does not necessarily reflect the actual dimensional ratio. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications can be made according to design and the like as long as the effects of the present disclosure can be achieved.

(1) First Embodiment (1.1) Electric Bicycle An electric bicycle 1 shown in FIG. 1 is a bicycle that can run using electric power. The electric bicycle 1 is a power-assisted bicycle in which the drive unit 4 assists the driver's stepping force (sometimes referred to as "pedal force"). The direction in which the electric bicycle 1 travels is defined as the "forward direction", the opposite direction to the forward direction is defined as the "rearward direction", and the forward direction and the rearward direction are collectively defined as the "front-rear direction". In addition, two directions that are perpendicular to the front-rear direction and are opposite to each other along the horizontal plane are collectively defined as the “left-right direction”. In addition, the left and right in the "horizontal direction" refer to the left and right when facing forward. However, these directional definitions are not meant to limit the manner in which the electric bicycle 1 and drive unit 4 are used.

As shown in FIG. 1, the electric bicycle 1 includes a frame 2, front wheels 31 and rear wheels 32, and a drive unit 4.

The frame 2 supports the person who drives the electric bicycle 1 (hereinafter referred to as the driver). The frame 2 and the load of the driver are supported on the ground via the front wheels 31 and the rear wheels 32 .

The frame 2 is mainly formed of a hollow tubular member and has a head tube 21 , top tube 22 , down tube 23 , seat tube 24 , seat stays 25 , chain stays 26 and bottom bracket shell (BB shell) 27 . The material of the frame 2 is an aluminum alloy containing aluminum as a main component. However, the material of the frame 2 is not limited to aluminum alloy, and may be metal such as chromium molybdenum steel, high-tensile steel, or titanium, carbon, or the like.

The head tube 21 is a hollow cylindrical member that extends upward while tilting rearward, and the upper end of the head tube 21 is located slightly rearward compared to the lower end. That is, the head tube 21 is inclined to be positioned further rearward as it goes upward. A handle post 601 is inserted into the upper surface of the head tube 21 , and the head tube 21 supports the handle post 601 rotatably around the axis of the head tube 21 . A handle bar 602 is fixed to the upper end of the handle post 601 . The handlebar 602 is provided with a hand operation unit for turning on/off the electric power assist. A pair of front forks 603 aligned in the horizontal direction extend downward from the lower end of the handle post 601 . A rotating shaft of the front wheel 31 is attached to each lower end of the pair of front forks 603 , and the pair of front forks 603 rotatably supports the front wheel 31 . When the handlebar 602 is rotated around the axis of the head tube 21, the pair of front forks 603 also rotates like the head tube 21, and the direction of the front wheel 31 changes.

The top tube 22 is a hollow cylindrical member that extends rearward from the top of the head tube 21 , and the rear end of the top tube 22 is positioned below the front end of the top tube 22 . That is, the top tube 22 is inclined so as to be located further downward as it goes rearward. A front end of the top tube 22 is fixed to a rear portion of the head tube 21 by welding or the like. The rear end of the top tube 22 is fixed to the front portion of the seat tube 24 by welding or the like.

The seat tube 24 is a hollow tubular member extending in the vertical direction, and the upper end of the seat tube 24 is located slightly behind the lower end. That is, the top tube 22 is inclined so as to be positioned more rearward as it goes upward. The rear end of the top tube 22 is fixed to the upper front portion of the seat tube 24 by welding or the like. A seat post 612 extending downward from the saddle 611 is inserted into the opening of the upper end surface of the seat tube 24 . The saddle 611 is attached to the seat tube 24 by fixing the seat post 612 to the seat tube 24 with a seat clamp or the like. The lower end of the seat tube 24 is fixed to the BB shell 27 within the bracket 5 by welding or the like.

The down tube 23 is a hollow cylindrical member that extends obliquely downward and rearward from the lower portion of the head tube 21, and the rear end of the down tube 23 is positioned lower than the front end. That is, the down tube 23 is inclined so as to be positioned further downward as it goes rearward. A front end of the down tube 23 is fixed to a rear portion of the head tube 21 by welding or the like. The rear end of the down tube 23 is fixed to the BB shell 27 within the bracket 5 by welding or the like.

The pair of chain stays 26 are positioned side by side in the left-right direction with the rear wheel 32 interposed therebetween. A rotating shaft of a rear wheel 32 is attached to each rear end of the pair of chain stays 26, and the pair of chain stays 26 rotatably supports the rear wheel 32. As shown in FIG. Each front end of the pair of chain stays 26 is connected to the BB shell 27 within the bracket 5 by fitting, fastening, welding, or the like. The chain stay 26 is a hollow or solid member extending rearward from the bracket 5 .

A pair of seat stays 25 are positioned side by side in the left-right direction with the rear wheel 32 interposed therebetween. The rear ends of the pair of seat stays 25 are attached to the rear ends of the pair of chain stays 26 by fitting, fastening, welding, or the like. Each front end of the pair of seat stays 25 is connected to an intermediate portion of the seat tube 24 by fitting, fastening, welding, or the like. The seat stay 25 is a hollow or solid member extending obliquely downward and rearward from the vicinity of the upper end of the seat tube 24 .

The bracket 5 has a bracket cover 51 and a transmission mechanism 52. The transmission mechanism 52 is housed in the bracket cover 51 . The transmission mechanism 52 includes a speed reducer using a planetary gear or the like, and transmits the assist force of the drive unit 4 to the crank sprocket 634 .

Further, a BB shell 27 of the frame 2 is positioned within the bracket 5, and the BB shell 27 is connected to the lower end of the seat tube 24, the rear end of the down tube 23, and the front ends of the pair of chainstays 26. there is The BB shell 27 is formed with a cylindrical through-hole extending in the left-right direction, and accommodates a bottom bracket having a crankshaft 633 extending in the left-right direction. On the left and right sides of the BB shell 27, one end of each crank arm 632 is attached to a crankshaft 633, respectively, and the other end of each crank arm 632 is attached to a pedal 631. A rider of the electric bicycle 1 can transmit a human-powered rotational force to the crankshaft 633 by pedaling the pedals 631 .

A crank sprocket 634 is attached to the crank shaft 633 , and the crank sprocket 634 rotates coaxially with the crank shaft 633 . Furthermore, a rear wheel sprocket 636 is attached to the hub of the rear wheel 32 , and the rear wheel sprocket 636 rotates coaxially with the rear wheel 32 . A chain 635 is wound between the crank sprocket 634 and the rear wheel sprocket 636 . When the rider of the electric bicycle 1 pedals the pedals 631, torque is transmitted to the rear wheel 32 via the crank arm 632, crankshaft 633, crank sprocket 634, chain 635, and rear wheel sprocket 636, causing the rear wheel 32 to rotate. do.

The drive unit 4 has a function of generating an assist force that assists the pedaling force of the driver, and is attached to the down tube 23 . When the crankshaft 633 rotates, the drive unit 4 detects the rotational force of the crankshaft 633 as a pedaling force and generates an assist force according to the value of the pedaling force. The assist force generated by the drive unit 4 is transmitted to the rear wheel 32 via the transmission mechanism 52 , crank sprocket 634 , chain 635 and rear wheel sprocket 636 .

(1.2) Drive Unit The drive unit 4 is arranged on the down tube 23 so as to fit within the projected plane of the cross section of the down tube 23 so as not to impair the appearance of the electric bicycle 1 . That is, the drive unit 4 is integrally attached to the down tube 23 so as not to protrude from the outer surface of the down tube 23 . In the first embodiment, the drive unit 4 is attached to the down tube 23 so as to fit into a recess formed outside the front portion 232 of the down tube 23 .

The drive unit 4 includes a unit case 40, a battery 41, a drive circuit 42, and a motor 43, as shown in FIGS.

(1.2.1) Circuit Configuration of Drive Unit The battery 41 is a secondary battery such as a lithium ion battery, a nickel hydrogen battery, a nickel cadmium battery, or a lead storage battery, and outputs a DC voltage. Note that the battery 41 may be configured to supply power to the headlights, the hand-operated operation unit for turning on/off the electric assist, and the like. The battery 41 includes at least one assembled battery in which a plurality of single cells (or cells) are connected in series. When the battery 41 includes multiple assembled batteries, the multiple assembled batteries are connected in parallel. Note that the battery 41 may be configured to include one or more single cells.

The drive circuit 42 receives a DC voltage from the battery 41 and outputs a three-phase AC voltage to the motor 43 . That is, the drive circuit 42 performs power conversion processing for converting DC power into AC power.

Specifically, the drive circuit 42 has six switching elements Q1 to Q6, a capacitor C1, and a control circuit 421, as shown in FIG. Each of the switching elements Q1 to Q6 is an N-channel enhancement type MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The switching elements Q1 to Q6 may be semiconductor switching elements other than MOSFETs, such as bipolar transistors.

The capacitor C1 is a capacitor that smoothes the DC voltage of the battery 41. The six switching elements Q1 to Q6 are three-phase bridge-connected and convert the DC voltage of the capacitor C1 into three-phase AC voltage.

The switching elements Q1 to Q6 constitute a first arm having switching elements Q1 and Q2, a second arm having switching elements Q3 and Q4, and a third arm having switching elements Q5 and Q6. In the first arm, the drain D1 of the switching element Q1 is connected to the positive electrode of the capacitor C1, the source S1 of the switching element Q1 is connected to the drain D2 of the switching element Q2, and the source S2 of the switching element Q2 is connected to the positive electrode of the capacitor C1. Connect to the negative pole. In the second arm, the drain D3 of the switching element Q3 is connected to the positive electrode of the capacitor C1, the source S3 of the switching element Q3 is connected to the drain D4 of the switching element Q4, and the source S4 of the switching element Q4 is connected to the positive electrode of the capacitor C1. Connect to the negative pole. In the third arm, the drain D5 of the switching element Q5 is connected to the positive electrode of the capacitor C1, the source S5 of the switching element Q5 is connected to the drain D6 of the switching element Q6, and the source S6 of the switching element Q6 is connected to the positive electrode of the capacitor C1. Connect to the negative pole.

The control circuit 421 applies gate voltages to the gates G1 to G6 of the switching elements Q1 to Q6 to turn the switching elements Q1 to Q6 on and off, thereby operating the switching elements Q1 to Q6 as a three-phase inverter. The control circuit 421 has a computer such as a microcomputer having a processor and memory. In this case, the computer implements at least part of the functions of the control circuit 421 by causing the processor to execute a program stored in the memory. The program executed by the processor is pre-recorded in the memory of the computer here, but may be provided by being recorded in a non-temporary recording medium such as a memory card, or may be provided through an electric communication line such as the Internet. may Also, the control circuit 421 may be configured by combining a computer with discrete components.

The motor 43 is a brushless motor or the like. A rotating shaft 431 of the motor 43 is rotated by a three-phase AC voltage supplied from the drive circuit 42 . A rotating shaft 431 of the motor 43 is connected to the transmission mechanism 52 . Therefore, the assist force generated by rotating the rotating shaft 431 of the motor 43 is transmitted to the crank sprocket 634 via the transmission mechanism 52 .

(1.2.2) Mounting of Drive Unit The down tube 23 corresponds to a connection member that connects the head tube 21 and the bottom bracket shell 27 . The down tube 23 has an elongated shape extending from the head tube 21 toward the bottom bracket shell 27 , and a recess 230 extending along the longitudinal direction of the down tube 23 is formed in the rear portion 231 of the down tube 23 . The drive unit 4 is attached so as to fit into the recess 230 .

The unit case 40 is a hollow rod that constitutes the outer shell of the drive unit 4, and is made of resin or the like. A unit case 40 houses a battery 41 , a drive circuit 42 and a motor 43 . A heat radiating portion 403 (see FIGS. 2 and 4) is formed on the front surface of the unit case 40 . The unit case 40 is attached to the recess 230 of the down tube 23 so as to block the recess 230 , and the battery 41 , drive circuit 42 and motor 43 are positioned inside the down tube 23 . The unit case 40 has a locking mechanism, a fitting mechanism, or a screwing mechanism, and is fixed to the down tube 23 by locking, fitting, screwing, or the like. The rear surface of the unit case 40 covering the recess 230 is flush with the outer surface of the down tube 23 . Alternatively, the rear surface of the unit case 40 covering the recess 230 is located inside the down tube 23 from the outer surface of the down tube 23 . Also, the heat radiating portion 403 of the drive unit 4 attached to the down tube 23 faces the front portion 232 of the down tube 23 . That is, the drive unit 4 is included in the projection plane of the down tube 23 when viewed from the axial direction of the down tube 23 . Note that “the driving unit 4 is included in the projection plane of the down tube 23 ” includes that the contour of the driving unit 4 matches the contour of the projection plane of the down tube 23 .

As described above, the drive unit 4 of the first embodiment is attached to the down tube 23 so as to be integrated with the down tube 23 without protruding from the outer surface of the down tube 23 . Therefore, the drive unit 4 can improve the appearance of the electric bicycle 1 .

Moreover, by mounting the drive unit 4 on the rear portion 231 of the down tube 23, the drive unit 4 is prevented from falling off from the down tube 23 compared to the case where the drive unit 4 is mounted on the front portion 232 of the down tube 23. can. Furthermore, by attaching the drive unit 4 to the rear portion 231 of the down tube 23 , compared to the case where the drive unit 4 is attached to the front portion 232 of the down tube 23 , when the electric bicycle 1 is running, the drive unit 4 is more likely to be hit by flying stones and the like. becomes difficult to collide with

As shown in FIG. 2, the unit case 40 has an elongated shape, and both longitudinal ends of the unit case 40 are a first end 401 and a second end 402 . When unit case 40 is mounted in recess 230 , first end 401 is closer to head tube 21 than second end 402 , and second end 402 is closer to bracket 5 than first end 401 .

Inside the unit case 40, the battery 41, the drive circuit 42, and the motor 43 are mounted in this order from the first end 401 to the second end 402. . Specifically, the battery 41 is attached to the first end 401 side of the unit case 40 , and the motor 43 is attached to the second end 402 side of the unit case 40 . Drive circuit 42 is positioned between battery 41 and motor 43 . The second end 402 is located near the bracket 5 and the motor 43 is arranged adjacent to the transmission mechanism 52 within the bracket 5 . Therefore, the drive unit 4 can shorten the distance between the motor 43 and the transmission mechanism 52, and can reduce the transmission loss of the assist force. Also, since the battery 41, the drive circuit 42, and the motor 43 are located near the bottom bracket shell 27 in the order of the motor 43, the drive circuit 42, and the battery 41, the wiring between the battery 41, the drive circuit 42, and the motor 43 is length can be shortened, and electrical loss can be reduced.

Also, the unit case 40 is preferably divided into a case 40a to which the battery 41 is attached and a case 40b to which the drive circuit 42 and the motor 43 are attached (see FIG. 2). In this case, the case 40a is detachably attached to the case 40b, and the battery 41 is detachably attached to the case 40a. Therefore, when the unit case 40 is attached to the recess 230 of the down tube 23, the case 40a is removed from the case 40b, the battery 41 attached to the case 40a is removed, and another battery 41 is attached to the case 40a. , the battery 41 can be replaced by reattaching the case 40a to the case 40b. Therefore, the replacement work of the battery 41 is facilitated.

(1.2.3) Heat Dissipation of Drive Unit A heat dissipation portion 403 (see FIGS. 2 and 4) of the drive unit 4 is formed on the front surface of the unit case 40 and has a heat dissipation function of dissipating heat generated by the drive unit 4 . The heat dissipation part 403 has heat dissipation fins 404 . The radiation fins 404 are rectangular convex bodies extending from the first end 401 toward the second end 402 of the unit case 40 . In the drive unit 4 attached to the concave portion 230 , the heat radiating fin 404 is a convex body extending along the longitudinal direction of the down tube 23 facing the front portion 232 of the down tube 23 . In FIGS. 2 and 4, two heat radiation fins 404 are arranged side by side in the left-right direction, and the tips of the heat radiation fins 404 face forward. That is, the front surface of the unit case 40 is the uneven heat dissipation portion 403, and the surface area of the front surface of the unit case 40 becomes larger than when the front surface of the unit case 40 is flat, thereby achieving efficient heat dissipation.

A heat radiating portion 403 of the drive unit 4 attached to the down tube 23 faces the front portion 232 of the down tube 23 . Therefore, as shown in FIG. 4 , the front portion 232 of the down tube 23 preferably has an insertion hole 233 at a location facing the heat radiating portion 403 . In FIG. 4, the down tube 23 has six insertion holes 233 with circular cross sections. When the electric bicycle 1 runs (forwards), air flows into the down tube 23 from the front of the electric bicycle 1 through the insertion hole 233 . The air that has flowed into the down tube 23 moves upward or downward along the heat radiation fins 404 extending in the longitudinal direction of the down tube 23 . That is, the drive unit 4 is cooled by the air that has flowed into the down tube 23 from the insertion hole 233, and the ability to dissipate heat from the drive unit 4 is improved. The heat generated by the drive unit 4 includes heat generated by the battery 41, heat generated by the switching elements Q1 to Q6 of the drive circuit 42, and heat generated by the motor 43. FIG. In addition, the number of the radiation fins 404 may be other than two, and may be one or three or more.

It should be noted that the down tube 23 only needs to have at least one insertion hole 233 . Also, the cross-sectional shape of the insertion hole may be other than circular, and may be, for example, triangular, quadrangular, elliptical, linear, or grid-like.

Also, between at least one of the battery 41, drive circuit 42, and motor 43 and the unit case 40, a thermally conductive member such as a silicon sheet or silicon compound may be placed. As a result, the heat dissipation performance of the drive unit 4 is further improved.

Also, the switching elements Q1 to Q6 of the drive circuit 42 are preferably positioned to face the front portion 232 of the down tube 23 when the drive unit 4 is mounted inside the down tube 23 . In this case, the switching elements Q1 to Q6 are efficiently dissipated.

(1.3) Modification 1
As shown in FIG. 5 , the drive unit 4 may be attached to the side 234 of the downtube 23 . In this case, a recess 235 is formed in the side portion 234 of the down tube 23 , and the drive unit 4 is attached so as to fit in the recess 235 .

The drive unit 4 of this modified example is also integrally attached to the down tube 23 without protruding from the outer surface of the down tube 23 . Mounting the drive unit 4 on the side portion 234 of the down tube 23 facilitates attachment and detachment of the drive unit 4 with respect to the down tube 23 .

(1.4) Modification 2
The heat radiating portion 403 may have a rectangular projection extending in the lateral direction on the front surface of the unit case 40 as a heat radiating fin.

(2) Second Embodiment FIG. 6 shows an electric bicycle 1A and a drive unit 4A according to a second embodiment. In addition, the same code|symbol is attached|subjected to the structure similar to 1st Embodiment, and description is abbreviate|omitted.

The down tube 23 of the electric bicycle 1A is a hollow cylindrical member that extends obliquely downward and rearward from the lower portion of the head tube 21, and does not have the recess 230 of the first embodiment.

The drive unit 4A is arranged on the down tube 23 so as to fit within the projected plane of the cross section of the down tube 23 so as not to impair the appearance of the electric bicycle 1A. That is, the drive unit 4A is integrally attached to the down tube 23 so as not to protrude from the outer surface of the down tube 23 . In the second embodiment, the drive unit 4A is attached inside the down tube 23 . The drive unit 4A includes a battery 41, a drive circuit 42, and a motor 43. Therefore, the drive unit 4A can improve the appearance of the electric bicycle 1A.

(2.1) Configuration of Drive Circuit As shown in FIGS. 7A, 7B, and 8, the drive circuit 42 includes a rectangular plate-shaped substrate 420, which includes switching elements Q1 to Q6, a capacitor C1, and a control circuit 421 (see FIG. 3). The substrate 420 has a rectangular first mounting surface 4201 and a second rectangular mounting surface 4202 facing each other. 7A is a plan view of the drive circuit 42 viewed from the first mounting surface 4201 side. FIG. 7B is a perspective view of the second mounting surface 4202 when the drive circuit 42 is viewed from the first mounting surface 4201 side. 8 is a side view of the drive circuit 42. FIG.

The switching elements Q1, Q3, and Q5 are mounted on the first mounting surface 4201. A conductor W<b>1 made of copper foil or the like is formed on the first mounting surface 4201 , and the conductor W<b>1 is formed in an elongated rectangular shape along the longitudinal direction of the first mounting surface 4201 . The switching elements Q1, Q3, Q5 are arranged side by side along the longitudinal direction of the conductor W1, and the respective drains D1, D3, D5 of the switching elements Q1, Q3, Q5 are mechanically and electrically connected to the conductor W1 by soldering or the like. connected to

　On the second mounting surface 4202, the switching elements Q2, Q4, Q6, the capacitor C1, and the control circuit 421 are mounted. A conductor W<b>2 made of copper foil or the like is formed on the second mounting surface 4202 , and the conductor W<b>2 is formed in an elongated rectangular shape along the longitudinal direction of the second mounting surface 4202 . The switching elements Q2, Q4, Q6 are arranged side by side along the longitudinal direction of the conductor W2, and the respective sources S2, S4, S6 of the switching elements Q2, Q4, Q6 are mechanically and electrically connected to the conductor W2 by soldering or the like. connected to

The switching elements Q1 and Q2 are arranged facing each other in the thickness direction of the substrate 420 . Switching elements Q3 and Q4 are arranged to face each other in the thickness direction of substrate 420 . Switching elements Q5 and Q6 are arranged to face each other in the thickness direction of substrate 420 . That is, when viewed from the thickness direction of the substrate 420, the projection planes of the switching elements Q1 and Q2, the projection planes of the switching elements Q3 and Q4, and the projection planes of the switching elements Q5 and Q6 are respectively overlap each other. Therefore, the wiring length between the switching elements Q1 and Q2, the wiring length between the switching elements Q3 and Q4, and the wiring length between the switching elements Q5 and Q6 can be shortened. Also, the space required for mounting the switching elements Q1 to Q6 can be reduced.

One end of the conductor W1 is connected to the positive electrode of the capacitor C1, and one end of the conductor W2 is connected to the negative electrode of the capacitor C1. That is, the direction of the current flowing through the conductor W1 and the direction of the current flowing through the conductor W2 are opposite to each other. Therefore, the conductors W1 and W2 are routed so that the projected planes of the conductors W1 and W2 overlap (or almost overlap) when viewed from the thickness direction of the substrate 420 . In other words, the conductors W1 and W2 are formed in the same shape (or substantially the same shape) so as to face each other in the thickness direction of the substrate 420 . Since the direction of the magnetic field generated by the current flowing through the conductor W1 and the direction of the magnetic field generated by the current flowing through the conductor W2 are opposite to each other, electrical noise emitted from the drive circuit 42 can be suppressed. At least a part of each projection plane of the conductors W1 and W2 should just overlap each other.

(2.2) Heat Dissipation of Drive Circuit The drive circuit 42 includes switching elements Q1 to Q6 as shown in FIG. 2, and heat is generated due to power loss in the switching elements Q1 to Q6. Therefore, as shown in FIGS. 9 to 11, a heat transfer portion 44 is arranged inside the down tube 23, which is a hollow cylindrical member. The heat transfer portion 44 is thermally coupled to the switching elements Q1 to Q6 of the drive circuit 42 within the down tube 23 and is also thermally coupled to the down tube 23 . That is, the heat transfer portion 44 has a function of thermally coupling the switching elements Q1 to Q6 and the down tube 23 and transferring the heat generated by the switching elements Q1 to Q6 to the down tube 23 to dissipate the heat. As a result, it is possible to further suppress the temperature of the drive circuit 42 from becoming excessively high. It should be noted that the heat transfer portion 44 is preferably made of metal such as an aluminum alloy, copper, or iron.

FIG. 9 shows a first example of the heat transfer section 44. FIG. In FIG. 9 , the down tube 23 has an annular cross-sectional shape, and two

heat transfer portions

441 and 442 are housed inside the down tube 23 as the heat transfer portion 44 . The heat transfer portion 441 is arranged on the right side inside the down tube 23 and has a shape extending along the longitudinal direction of the down tube 23 . The heat transfer portion 442 is arranged on the left side inside the down tube 23 and has a shape extending along the longitudinal direction of the down tube 23 . The

heat transfer portions

441 and 442 respectively include

flat surfaces

44a and 44c facing each other in the left-right direction. The heat transfer portion 441 further includes a curved surface 44b that is in surface contact with the inner surface of the down tube 23 from the front portion 232 to the right side. The heat transfer portion 442 further includes a curved surface 44d that is in surface contact with the inner surface of the down tube 23 from the front portion 232 to the left side. The drive circuit 42 is positioned between the plane 44a and the plane 44c, and arranged forward in the down tube 23 so that the longitudinal direction of the substrate 420 is aligned with the longitudinal direction of the down tube 23 . That is, drive circuit 42 is closer to front portion 232 of down tube 23 than to rear portion 231 of down tube 23 .

In the drive circuit 42 positioned between the plane 44a and the plane 44c, the first mounting surface 4201 of the substrate 420 faces the plane 44a, and the second mounting surface 4202 of the substrate 420 faces the plane 44c. The packages of the switching elements Q1, Q3, Q5 are in surface contact with the plane 44a, and the packages of the switching elements Q2, Q4, Q6 are in surface contact with the plane 44c. As a result, the heat generated by the switching elements Q1, Q3, and Q5 is transferred to the down tube 23 via the heat transfer portion 441 and radiated. Also, the heat generated by the switching elements Q2, Q4, and Q6 is transferred to the down tube 23 via the heat transfer portion 442 and radiated.

FIG. 10 shows a second example of the heat transfer section 44. FIG. In FIG. 10 , the cross-sectional shape of the down tube 23 is a square ring, and two

heat transfer portions

443 and 444 are housed inside the down tube 23 as the heat transfer portion 44 . The heat transfer portion 443 is arranged on the right side inside the down tube 23 and has a shape extending along the longitudinal direction of the down tube 23 . The heat transfer portion 444 is arranged on the left side inside the down tube 23 and has a shape extending along the longitudinal direction of the down tube 23 . The

heat transfer portions

443 and 444 respectively include flat surfaces 44e and 44h facing each other in the left-right direction. The heat transfer portion 443 further includes

flat surfaces

44f and 44g that are in surface contact with the inner surface from the front portion 232 to the right side portion of the down tube 23 . The heat transfer portion 444 further includes

flat surfaces

44 i and 44 j that are in surface contact with the inner surface from the front portion 232 to the left side of the down tube 23 . The drive circuit 42 is located between the plane 44e and the plane 44h, and is arranged forward in the down tube 23 so that the longitudinal direction of the substrate 420 is along the longitudinal direction of the down tube 23. As shown in FIG. That is, drive circuit 42 is closer to front portion 232 of down tube 23 than to rear portion 231 of down tube 23 .

In the drive circuit 42 located between the plane 44e and the plane 44h, the first mounting surface 4201 of the substrate 420 faces the plane 44e, and the second mounting surface 4202 of the substrate 420 faces the plane 44h. The packages of the switching elements Q1, Q3, Q5 are in surface contact with the plane 44e, and the packages of the switching elements Q2, Q4, Q6 are in surface contact with the plane 44h. As a result, the heat generated by the switching elements Q1, Q3, and Q5 is transferred to the down tube 23 via the heat transfer portion 443 and radiated. Also, the heat generated by the switching elements Q2, Q4, and Q6 is transferred to the down tube 23 via the heat transfer portion 444 and radiated.

FIG. 11 shows a third example of the heat transfer section 44. FIG. In FIG. 11 , the down tube 23 has an annular cross-sectional shape, and one heat transfer portion 445 is housed inside the down tube 23 as the heat transfer portion 44 . The heat transfer portion 445 has a flat surface 44 k facing the rear portion 231 and a curved surface 44 m that contacts the inner surface of the front portion 232 of the down tube 23 . The drive circuit 42 is located behind the plane 44 k and arranged forward in the down tube 23 so that the longitudinal direction of the substrate 420 is aligned with the longitudinal direction of the down tube 23 . That is, drive circuit 42 is closer to front portion 232 of down tube 23 than to rear portion 231 of down tube 23 .

In the drive circuit 42 of FIG. 11, the switching elements Q1 to Q6 are mounted on the mounting surface 4203 of the substrate 420, and the mounting surface 4203 faces the plane 44k. Each package of the switching elements Q1 to Q6 is in surface contact with the plane 44k. As a result, the heat generated by each of the switching elements Q1 to Q6 is transferred to the down tube 23 via the heat transfer portion 445 and radiated.

Also, the heat transfer portion 44 is in surface contact with the front portion 232 of the down tube 23 . Therefore, when the electric bicycle 1A runs (forwards), the relative air flow F1 from the front of the electric bicycle 1A toward the front portion 232 of the down tube 23 increases the amount of heat released by the heat transfer portion 44 .

(2.3) Modification 3
Of the battery 41, drive circuit 42, and motor 43 included in the drive unit 4A, at least the battery 41 is preferably detachable from the down tube 23. As shown in FIG. In this case, a portion of the down tube 23 is configured to be openable and closable at least for attachment and detachment of the battery 41 . For example, only the battery 41 included in the drive unit 4A, the battery 41 and the drive circuit 42 included in the drive unit 4A, or the battery 41, the drive circuit 42, and the motor 43 included in the drive unit 4A are configured to be detachable from the down tube 23. be.

In addition, it is preferable that the drive unit 4A further includes heat radiation fins to dissipate the heat generated by the drive unit 4A. The heat radiation fins preferably have a shape extending along the longitudinal direction of the down tube 23 .

Further, an insertion hole 233 may be provided in the front portion 232 of the down tube 23, and the air flowing into the down tube 23 from the insertion hole 233 may cool the drive unit 4A.

Further, the front surface of the down tube 23 may be made uneven so that the front surface of the down tube 23 also functions as a heat radiating section.

It should be noted that the configurations of the first embodiment, the second embodiment, and the modifications described above can be appropriately combined.

(3) Summary The drive unit (4, 4A) of the first aspect according to the above embodiment is a drive unit for the electric bicycle (1, 1A). The drive unit (4, 4A) includes a motor (43) that generates driving force for propelling the electric bicycle (1), and a drive circuit (42) that drives the motor (43). The motor (43) and the drive circuit (42) are connected to the connecting member (23) connecting the head tube (21) and the bottom bracket shell (27) of the electric bicycle (1). positioned to fit inside.

The drive unit (4, 4A) described above can improve the appearance of the electric bicycle (1, 1A).

In addition, in the drive unit (4) of the second aspect according to the embodiment, in the first aspect, the motor (43) and the drive circuit (42) are formed outside the front portion (232) of the connection member (23). are preferably mounted in recesses (230, 235).

The drive unit (4) described above can improve the appearance of the electric bicycle (1).

Further, in the third aspect of the drive unit (4) according to the embodiment, in the second aspect, the motor (43) and the drive circuit (42) are formed in the rear part (231) of the connection member (23). (230) is preferably attached.

The drive unit (4) described above can prevent the drive unit (4) from coming off the connection member (23). Furthermore, when the electric bicycle (1) is running, it becomes difficult for stones and the like to collide with the drive unit (4).

In addition, in the drive unit (4) of the fourth aspect according to the embodiment, in the second aspect, the motor (43) and the drive circuit (42) are formed on the side portion (234) of the connection member (23). It is preferably attached to (235).

The drive unit (4) described above can be easily attached to and detached from the connection member (23).

Further, in the drive unit (4A) of the fifth aspect according to the embodiment, it is preferable that the motor (43) and the drive circuit (42) are attached inside the connection member (23) in the first aspect.

The drive unit (4A) described above can improve the appearance of the electric bicycle (1A).

In addition, the drive unit (4, 4A) of the sixth aspect according to the embodiment, in any one of the first to fifth aspects, further includes a battery (41) for supplying power to the drive circuit (42). It is preferable to have

The drive unit (4, 4A) described above can secure a storage space for the battery (41) while improving the appearance of the electric bicycle (1, 1A).

In addition, in the drive unit (4, 4A) of the seventh aspect according to the embodiment, in the sixth aspect, the battery (41) is preferably detachable from the connection member (23).

In the drive units (4, 4A) described above, the batteries (41) can be easily replaced.

In addition, it is preferable that the drive unit (4, 4A) of the eighth aspect according to the embodiment further includes heat radiation fins (404) in any one of the first to seventh aspects.

The drive unit (4, 4A) described above can efficiently dissipate heat from the drive unit (4, 4A).

In addition, in the drive unit (4, 4A) of the ninth aspect according to the embodiment, in the eighth aspect, the connection member (23) is elongated, and the heat radiation fins (404) are arranged so that the connection member (23 ) preferably extends along the length of the .

Further, in the drive unit (4, 4A) of the tenth aspect according to the embodiment, in any one of the first to ninth aspects, the connection member is a down tube (23) of the electric bicycle (1, 1A). ) is preferred.

Further, an electric bicycle (1, 1A) of an eleventh aspect according to the embodiment includes any one of the first to tenth drive units (4, 4A) and a connection to which the drive unit (4, 4A) is attached. a member (23);

The electric bicycle (1, 1A) described above can improve its appearance.

Further, in the electric bicycle (1, 1A) of the twelfth aspect according to the embodiment, in the eleventh aspect, the connection member (23) has at least one insertion hole in the front portion (232) of the connection member (23). (233) is preferably provided.

The electric bicycle (1, 1A) described above can efficiently dissipate heat from the drive unit (4, 4A).

1, 1A electric bicycle 21 head tube 23 down tube (connecting member)
230 recessed portion 231 rear portion 232 front portion 233 insertion hole 234 side portion 235 recessed portion 27

bottom bracket shell

4, 4A drive unit 41 battery 43 motor 42 drive circuit 404 heat radiation fin

Claims

A drive unit for an electric bicycle,
a motor that generates driving force for propelling the electric bicycle;
a drive circuit for driving the motor,
A drive unit in which the motor and the drive circuit are arranged in a connection member that connects the head tube and the bottom bracket shell of the electric bicycle so as to fit within a projection plane of the cross section of the connection member.
2. The drive unit according to claim 1, wherein the motor and the drive circuit are mounted in recesses formed in portions other than the front portion of the connection member.
3. The drive unit of claim 2, wherein the motor and the drive circuit are mounted in the recess formed in the rear portion of the connecting member.
3. The drive unit of claim 2, wherein the motor and the drive circuit are mounted in the recess formed in the side of the connecting member.
2. The drive unit of claim 1, wherein the motor and the drive circuit are mounted inside the connecting member.
6. A drive unit as claimed in any one of claims 1 to 5, further comprising a battery for powering the drive circuit.
7. The drive unit according to claim 6, wherein the battery is detachable with respect to the connection member.
8. The drive unit according to any one of claims 1 to 7, further comprising heat radiating fins.
The connection member has an elongated shape,
9. The drive unit according to claim 8, wherein said heat radiating fins extend along the longitudinal direction of said connecting member.
The drive unit according to any one of claims 1 to 9, wherein the connection member is a down tube of the electric bicycle.
A drive unit according to any one of claims 1 to 10;
and the connection member to which the drive unit is attached.
12. The electric bicycle according to claim 11, wherein the connecting member has at least one insertion hole in a front portion of the connecting member.