Motor unit and electric vehicle

Abstract

A motor unit (100) to be used in an electric vehicle comprises: a power source IC (170); a substrate (150) on which the power source IC (170) is mounted; and a case (160) which accommodates the substrate (150). The case (160) includes a screw boss (163) that protrudes towards the substrate (150) and is connected to the substrate (150), and a heat dissipation section (164) that protrudes towards the substrate (150) and is connected to a side of the screw boss (163).

Description

Motor unit and electric vehicle

[0001] The present invention relates to a motor unit and an electric vehicle.

[0002] Patent Document 1 discloses an electric bicycle equipped with a motor unit. The motor unit includes a motor, a substrate on which switching elements for driving the motor are mounted, and a case that houses the substrate. A through hole is provided in the substrate, and a metal foil is provided on the inner surface of the through hole to which the switching elements are thermally connected. A portion of the case on the opposite side of the substrate from the switching elements is thermally connected to the metal foil. It is stated that this configuration further increases the amount of heat dissipated from the switching elements.

[0003] Japanese Patent Application Laid-Open No. 2023-49765

[0004] In the conventional motor unit described above, part of the case is recessed toward the board to thermally connect it to the metal foil on the board. This increases the volume of the recessed part of the case, which creates the problem of increasing the weight of the case.

[0005] Therefore, an object of the present invention is to provide a motor unit that has high heat dissipation properties and is lightweight, and an electric vehicle equipped with such a motor unit.

[0006] A motor unit according to one aspect of the present invention is a motor unit used in an electric vehicle, and comprises a power supply circuit, a board on which the power supply circuit is mounted, and a case that houses the board, wherein the case includes a first convex portion that protrudes toward the board and is connected to the board, and a second convex portion that protrudes toward the board and is connected to the side of the first convex portion.

[0007] An electric vehicle according to one aspect of the present invention includes the motor unit according to the above aspect, wheels to which rotational force from the motor unit is transmitted, and a frame that supports the motor unit and the wheels.

[0008] According to the present invention, it is possible to provide a motor unit that has high heat dissipation properties and is lightweight, and an electric vehicle equipped with the motor unit.

[0009] Fig. 1 is a side view of an electric bicycle equipped with a motor unit according to an embodiment. Fig. 2 is a cross-sectional view of the motor unit according to an embodiment. Fig. 3 is a partially exploded perspective view showing a board and case of the motor unit according to an embodiment. Fig. 4 is a perspective view showing a heat dissipation structure of the case of the motor unit according to an embodiment. Fig. 5 is a cross-sectional view showing a power supply IC and heat dissipation structure provided on the board of the motor unit according to an embodiment.

[0010] A motor unit and an electric vehicle according to embodiments of the present invention will be described in detail below with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangements and connection forms, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0011] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0012] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or perpendicular, terms indicating the shape of elements, such as rectangular or circular, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0013] Furthermore, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

[0014] In addition, in this specification, "forward" refers to the direction of travel of an electric vehicle during normal driving, and "rear" refers to the opposite direction. Specifically, in the case of an electric bicycle, the direction in which the handlebars are positioned relative to the saddle is "forward." "Forward-backward direction" refers to the direction from rear to forward, and the opposite direction, among multiple horizontal directions (any direction parallel to the ground). "Right-left direction" refers to the direction perpendicular to the forward-backward direction, and when facing forward, the left side is the "left" and the right side is the "right."

[0015] (Embodiment) [Configuration] First, the configuration of an electric bicycle according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a side view showing the configuration of an electric bicycle 1 equipped with a motor unit 100 according to this embodiment.

[0016] The electric bicycle 1 shown in Figure 1 is an example of an electric vehicle and is a bicycle with an electric assist function. The electric assist function is a function that assists the forward movement of the electric bicycle 1 based on the pedaling force applied to the pedals 17 by the user riding the electric bicycle 1, and is executed in a so-called assist mode.

[0017] As shown in FIG. 1 , the electric bicycle 1 includes a body 10 , a battery 20 , and a motor unit 100 .

[0018] The body 10 is the main body of the electric bicycle 1. The body 10 includes a frame 11, a front wheel 12, a rear wheel 13, a handlebar 14, a saddle 15, cranks 16, pedals 17, a chain 18, a front sprocket 19a, and a rear sprocket 19b.

[0019] The frame 11 is the framework of the electric bicycle 1. The frame 11 is made of, for example, metal, carbon, or synthetic resin. The frame 11 is formed by combining multiple tubular members such as a head tube, a down tube, a seat tube, a chainstay, and a front fork. The frame 11 may also have a shock-absorbing member such as a suspension. The frame 11 supports the front wheel 12, the rear wheel 13, the handlebars 14, the saddle 15, the crank 16, the chain 18, the front sprocket 19a, and the rear sprocket 19b.

[0020] The front wheels 12 have tires for driving the vehicle body 10. The front wheels 12 are the front wheels of two wheels aligned in the front-to-rear direction. The front wheels 12 are supported by the frame 11 so that they can rotate around an axis extending in the left-to-right direction. Note that the front wheels 12 may receive power from the motor unit 100, i.e., the rotational force of a motor 110 (see FIG. 2).

[0021] The rear wheel 13 has a tire for propelling the vehicle body 10. The rear wheel 13 is the rear wheel of two wheels aligned in the front-to-rear direction. The rear wheel 13 is supported by the frame 11 so that it can rotate about an axis extending in the left-to-right direction. In this embodiment, the rear wheel 13 receives power from the motor unit 100, i.e., the rotational force of the motor 110. The rear wheel 13 is connected to a front sprocket 19a via a chain 18 and a rear sprocket 19b.

[0022] The handlebars 14 are operated by a user riding the electric bicycle 1 to change the steering angle of the electric bicycle 1. The handlebars 14 are rotatably supported by the frame 11. A pair of grips and a pair of brake levers are provided at both ends of the handlebars 14. The pair of grips are held by the user's hands when the user is riding the electric bicycle 1 in an appropriate posture. The pair of grips are also held by the hands when pushing or supporting the electric bicycle 1 and walking, and receive forward pushing forces, etc. The pair of brake levers apply mechanical braking forces to the front wheel 12 and rear wheel 13, for example, by operating a brake device.

[0023] The saddle 15 is a portion on which a user sits. The saddle 15 is attached to the frame 11 so that the height thereof can be adjusted.

[0024] The crank 16 has a crankshaft 16a and a pair of crank arms 16b. One crank arm 16b is provided on each of the left and right sides of the motor unit 100, and is fixed to both ends of the crankshaft 16a, which extends in the left-right direction. One end of the crank arm 16b is rotatably fixed to the crankshaft 16a, and the pedal 17 is rotatably fixed to the other end of the crank arm 16b.

[0025] The pedals 17 receive pedaling force from the user riding the electric bicycle 1. The pedals 17 are attached to the longitudinal ends of each crank arm 16b on the opposite side from the crankshaft 16a. The pedals 17 are rotatably attached to the crank arms 16b. The rotation axis of the pedals 17 is approximately parallel to the rotation axis of the crankshaft 16a of the crank 16.

[0026] When a pedal force is applied to the pedal 17, the crank arm 16b rotates around the crank shaft 16a, and the manual driving force resulting from this rotation is transmitted to the rear wheel 13 via the front sprocket 19a, the chain 18, and the rear sprocket 19b. When the electric bicycle 1 operates in the assist mode, the manual driving force based on the pedal force and the auxiliary driving force of the motor 110 added to the manual driving force are transmitted to the rear wheel 13.

[0027] The chain 18 is an example of a power transmission member that transmits the rotational force of the front sprocket 19a to the rear sprocket 19b. The chain 18 connects the front sprocket 19a and the rear sprocket 19b. Note that instead of the chain 18, a belt, a shaft, a wire, a gear, or the like may be used as the power transmission member. For example, when the power transmission member is a belt, compared to when the power transmission member is a chain 18, effects such as quieter operation, improved durability, and reduced maintenance frequency can be expected.

[0028] The front sprocket 19a is attached to the crankshaft 16a of the crank arm 16b. When the user steps on the pedal 17, the front sprocket 19a rotates via the crank arm 16b and the crankshaft 16a. The rotational force of the front sprocket 19a is transmitted to the rear sprocket 19b attached to the rear wheel 13 via the chain 18. This causes the rear sprocket 19b to rotate, and the rear wheel 13 to rotate. The front sprocket 19a is also called the drive sprocket, and the rear sprocket 19b is also called the driven sprocket.

[0029] The battery 20 is a storage battery that stores power for driving the motor 110 of the motor unit 100. The battery 20 is, for example, a secondary battery, but may also be another charge / discharge element such as a capacitor. The battery 20 is electrically connected to the motor 110 and supplies power to the motor 110.

[0030] The battery 20 is removably fixed to the frame 11. There are no particular limitations on the mounting position of the battery 20. Furthermore, if the electric bicycle 1 is equipped with lighting devices such as a headlight and a taillight, and electronic devices such as a display unit, an operation unit (hand switch), and an electric gear shifter, the battery 20 can also supply power to these lighting devices and electronic devices.

[0031] The motor unit 100 is an example of a motor unit used in an electric vehicle. As shown in FIG. 2 , the motor unit 100 includes a motor 110, a crank rotation mechanism 120, a reduction gear mechanism 130, a crank rotation sensor unit 140, a substrate 150, a case 160, and a power supply IC 170. FIG. 2 is a cross-sectional view of the motor unit 100 according to this embodiment. FIG. 2 shows a cross section including the center of the crankshaft 16 a and the center of the motor shaft 113 of the motor 110. In FIG. 2 , some components such as the crankshaft 16 a, the motor shaft 113, and the large-diameter gear 131 are shown in a schematic plan view rather than in a cross-sectional view.

[0032] The motor 110 is an electric motor that receives power from the battery 20 and is driven under the control of a control circuit provided on the substrate 150. As shown in FIG. 2 , the motor 110 has a stator 111, a rotor 112, and a motor shaft (output shaft) 113.

[0033] The motor 110 is supported by a case 160 via bearings so that the rotor 112 and motor shaft 113 can rotate. Specifically, a stator 111 receives power from the battery 20 and rotates the rotor 112. The motor shaft 113 rotates in accordance with the rotation of the rotor 112. A toothed portion 114 is provided on the tip side of the motor shaft 113, and engages with a large-diameter gear 131 of the reduction mechanism 130. The rotation of the toothed portion 114 causes the large-diameter gear 131 to rotate.

[0034] The crankshaft 16a is disposed to pass through the case 160. The crankshaft 16a is rotatably supported by bearings. The crank rotation mechanism 120 includes a manual power transmission body 121, an intermediate cylinder 122, and an interlocking body 123. The manual power transmission body 121, the intermediate cylinder 122, and the interlocking body 123 are all cylindrical members, and the crankshaft 16a is inserted into the cylinders.

[0035] The power transmitting body 121 is fitted into a serration portion 124 provided on the crankshaft 16a and is arranged to rotate integrally with the crankshaft 16a. The intermediate cylinder 122 is rotatable relative to the crankshaft 16a and is arranged to rotate integrally with the power transmitting body 121 and the interlocking body 123. A front sprocket 19a (not shown in FIG. 2) is provided on the interlocking body 123 so as to rotate integrally with the interlocking body 123. The power transmitting body 121, intermediate cylinder 122, and interlocking body 123 are each provided with one or more serration portions (spline portions), and are fitted together to rotate integrally.

[0036] Furthermore, a one-way clutch (not shown) is disposed between the intermediate cylinder 122 and the interlocking body 123. The one-way clutch is disposed on the intermediate cylinder 122, and transmits rotational force in one direction from the intermediate cylinder 122 to the interlocking body 123 by the ratchet engaging with the interlocking body 123.

[0037] With this configuration, the crankshaft 16a is rotated by the force applied to the pedal 17, and the manual driving force resulting from this rotation is transmitted to the front sprocket 19a via the manual driving force transmission body 121, the intermediate cylinder body 122, the one-way clutch (not shown), and the interlocking body 123. When the front sprocket 19a is rotated by the manual driving force, the chain 18 attached to the front sprocket 19a rotates, causing the rear sprocket 19b and the rear wheel 13 to rotate.

[0038] Additionally, an auxiliary driving force from the motor 110 is transmitted to the interlocking body 123 via the speed reducer 130. In other words, the rotation of the interlocking body 123 can be assisted by the auxiliary driving force from the motor 110, so that the front sprocket 19 a, the rear sprocket 19 b, and the rear wheel 13 can be rotated in accordance with the rotation of the interlocking body 123.

[0039] The speed reduction mechanism 130 is configured to amplify the rotational torque (i.e., auxiliary driving force) of the motor 110 and transmit it to the interlocking member 123. Specifically, as shown in Fig. 2, the speed reduction mechanism 130 has a large diameter gear 131 and a small diameter gear 132. As described above, the large diameter gear 131 rotates in response to the rotation of the motor shaft 113 of the motor 110.

[0040] In the reduction mechanism 130, the small diameter gear 132 rotates integrally with the large diameter gear 131 on the same rotation axis. The small diameter gear 132 fits into the gear portion of the interlocking body 123. When the small diameter gear 132 rotates, the interlocking body 123 rotates.

[0041] In this manner, in this embodiment, the auxiliary driving force generated by the motor 110 is transmitted to the interlocking member 123 via the reduction gear mechanism 130. That is, when the rotor 112 and the motor shaft 113 of the motor 110 rotate, the interlocking member 123 also rotates, causing the front sprocket 19a to rotate. This causes the rear wheel 13 to rotate via the chain 18 and the rear sprocket 19b.

[0042] The crank rotation sensor unit 140 has a gear-shaped rotor 141 having the sensor shaft as its rotation axis. The rotor 141 of the crank rotation sensor unit 140 is provided so as to rotate integrally with the intermediate cylinder body 122.

[0043] The rotation of the rotor 141 is detected by a detector such as a photodetector. For example, the photodetector has a light-emitting portion and a light-receiving portion arranged opposite each other. The light-emitting portion and the light-receiving portion are fixed to, for example, the substrate 150 or the case 160. The rotor 141 is positioned so that its teeth block the path of light from the light-emitting portion to the light-receiving portion. As the rotor 141 rotates, the teeth block the light, and the number of times the light received by the light-receiving portion is blocked (or the number of times the light is successfully received) and the number of teeth on the rotor 141 are used to detect the rotation speed of the rotor 141. Because the rotor 141, the intermediate cylinder 122, and the crankshaft 16a rotate integrally, the rotation speed of the rotor 141 coincides with the rotation speed of the crankshaft 16a. In this manner, the crank rotation sensor 140 can detect the rotation speed of the crankshaft 16a.

[0044] The crank rotation sensor unit 140 may have any configuration as long as it can detect the rotation speed of the crankshaft 16a. The motor unit 100 may also include a motor rotation sensor that detects the rotation speed of the motor 110. The motor unit 100 may also include a pedal force sensor that detects the human driving force generated by the rotation of the crankshaft 16a based on the pedal force applied to the pedal 17.

[0045] The substrate 150 is a substrate on which various electronic components that constitute a control circuit for controlling the operation of the motor unit 100 are mounted. The control circuit includes a power supply circuit that generates the power supplied to the motor 110, a detection circuit that processes sensor signals output from various sensors, and the like. The electronic components include one or more integrated circuits including a power supply IC (Integrated Circuit) 170, electrolytic capacitors, capacitors, transistors, diodes, resistor elements, connectors, and the like. The substrate 150 is, for example, a printed wiring board. Metal wiring is provided on the substrate 150 to electrically connect the electronic components.

[0046] The substrate 150 has a first main surface 150a and a second main surface 150b opposite the first main surface 150a. The first main surface 150a and the second main surface 150b are a pair of flat surfaces parallel to each other. As shown in FIG. 2 , multiple electronic components, including a power supply IC 170, are mounted on the first main surface 150a. The stator 111 and rotor 112 of the motor 110 are disposed on the second main surface 150b side of the substrate 150. The motor shaft 113 and crankshaft 16a of the motor 110 are disposed so as to perpendicularly intersect with the substrate 150. The four rotation mechanisms (motor 110, crank rotation mechanism 120, reduction mechanism 130, and crank rotation sensor unit 140) included in the motor unit 100 are disposed so that their respective rotation axes are perpendicular to the first main surface 150a of the substrate 150. The substrate 150 is fixed to the case 160 using fasteners such as screws 190 (see FIG. 5).

[0047] The case 160 constitutes most of the outer shell of the motor unit 100. The circuit board 150 is housed and fixed in the case 160. The case 160 also houses the motor 110, the reduction mechanism 130, the crank rotation sensor unit 140, and part of the crank rotation mechanism 120. The crank shaft 16a of the crank rotation mechanism 120 is disposed so as to pass through the case 160. Both ends of the crank shaft 16a are located outside the case 160, and are connected to crank arms 16b.

[0048] The case 160 includes a first divided body 161 and a second divided body 162. The first divided body 161 and the second divided body 162 are assembled and fixed together with fastening members (not shown) such as screws to form the case 160. Specifically, the first divided body 161 and the second divided body 162 are each formed in a cylindrical shape with a bottom, and are arranged with their openings facing each other and the leading ends of their outer peripheral walls facing each other. The leading ends of the outer peripheral walls are provided with flanges with through holes, and the first divided body 161 and the second divided body 162 are fixed together with screws inserted into the through holes. Note that a gasket or the like may be provided between the leading ends of the outer peripheral walls of the first divided body 161 and the second divided body 162 to prevent moisture and the like from entering.

[0049] The first divided body 161 and the second divided body 162 are each formed using a metal material such as an aluminum alloy, a magnesium alloy, stainless steel, or steel, but may also be formed using carbon or resin. The first divided body 161 and the second divided body 162 are each integrally formed by die casting, injection molding, or the like.

[0050] The case 160 has a heat dissipation structure for dissipating heat generated by the power supply IC 170 provided on the substrate 150. A specific example of the heat dissipation structure of the case 160 will be described later.

[0051] The power supply IC 170 is an example of a power supply circuit. The power supply IC 170 includes a linear regulator or a DC / DC converter. The power supply IC 170 is provided with multiple switching elements such as transistors, which generate heat during operation. By efficiently dissipating the heat generated by the power supply IC 170, problems such as malfunctions caused by heat can be suppressed.

[0052] The power supply IC 170 generates the power to be supplied to the motor 110, for example, based on the power from the battery 20. Furthermore, if the electric bicycle 1 is equipped with lighting devices such as a headlight and a taillight, and electronic devices such as a display unit, an operation unit (hand switch), and an electric transmission, the power supply IC 170 may generate the power to be supplied to these lighting devices and electronic devices based on the power from the battery 20.

[0053] [Major Characteristic Configuration] Next, the major characteristic configuration of the motor unit 100 according to this embodiment will be described with reference to FIGS.

[0054] Fig. 3 is a partially exploded perspective view showing the substrate 150 and case 160 of the motor unit 100 according to this embodiment. Fig. 4 is a perspective view showing the heat dissipation structure of the case 160 of the motor unit 100 according to this embodiment. Fig. 5 is a cross-sectional view showing the power supply IC 170 and heat dissipation structure provided on the substrate 150 of the motor unit 100 according to this embodiment. As shown in Fig. 5, the motor unit 100 further includes a heat dissipation sheet 180 and screws 190.

[0055] In the present embodiment, case 160 includes a screw boss portion 163 and a heat dissipation portion 164. Specifically, first divided body 161 of case 160 includes screw boss portion 163 and heat dissipation portion 164. Board 150 is fixed to first divided body 161, and stator 111 and rotor 112 of motor 110 are housed therein.

[0056] The screw boss portion 163 is an example of a first protrusion that protrudes toward the substrate 150 and is connected to the substrate 150. The screw boss portion 163 protrudes toward the substrate 150 from a part of the bottom surface of the bottomed cylindrical first divided body 161. The screw boss portion 163 is a bottomed cylindrical protrusion, but is not limited to this. A screw hole 163a is provided at the tip portion corresponding to the bottom of the bottomed cylindrical shape, i.e., the tip portion in the protruding direction of the screw boss portion 163, as shown in Figures 3 and 4 .

[0057] 5 , a screw 190 is inserted into the screw hole 163a. ​​Specifically, a screw hole 150c is provided in the substrate 150. The screw 190 is inserted into the screw hole 150c and then the screw hole 163a, and the substrate 150 is sandwiched and fixed between the head of the screw 190 and the tip of the screw boss portion 163.

[0058] The heat dissipation portion 164 is an example of a second convex portion that protrudes toward the substrate 150. The heat dissipation portion 164 protrudes toward the substrate 150 from a part of the bottom surface of the first divided body 161, which has a cylindrical shape with a bottom. The shape of the heat dissipation portion 164 is a convex portion in the shape of a rectangular cylinder with a bottom, but is not limited to this. The tip portion corresponding to the bottom of the rectangular cylinder with a bottom, i.e., tip portion 164a of the heat dissipation portion 164, is a flat surface.

[0059] 5, in this embodiment, the distance between the tip 164a of the heat dissipation portion 164 and the substrate 150 is longer than the distance between the screw boss portion 163 and the substrate 150. In other words, the height of the heat dissipation portion 164 is shorter than the height of the screw boss portion 163. Note that the "height" here refers to the length in the protruding direction of the screw boss portion 163 or the heat dissipation portion 164. The tip of the screw boss portion 163 is in contact with the second main surface 150b of the substrate 150. In contrast, the tip 164a of the heat dissipation portion 164 is not in contact with the second main surface 150b, leaving a gap therebetween. The heat dissipation sheet 180 is provided in this gap.

[0060] The heat dissipation sheet 180 is an example of a heat dissipation member, and is disposed between the tip end 164a of the heat dissipation portion 164 and the second main surface 150b of the substrate 150, and is in contact with each other. The heat dissipation sheet 180 is a sheet-like member formed using a resin with high thermal conductivity or the like. The heat dissipation sheet 180 can efficiently transfer heat from the substrate 150 to the heat dissipation portion 164.

[0061] In a plan view of the substrate 150, the power supply IC 170 and the heat dissipation section 164 overlap. This allows the power supply IC 170, which is a heat source, to be thermally connected to the heat dissipation section 164 over the shortest distance. Specifically, heat generated in the power supply IC 170 is quickly transferred to the heat dissipation section 164 via the substrate 150 and the heat dissipation sheet 180. This improves heat dissipation.

[0062] The size of the tip 164a of the heat dissipation portion 164 in a plan view is larger than, for example, the size of the power supply IC 170 in a plan view. In a plan view, the power supply IC 170 is arranged so that its entirety overlaps the tip 164a of the heat dissipation portion 164. Furthermore, the area of ​​the tip 164a of the heat dissipation portion 164 is larger than the area of ​​the tip of the screw boss portion 163. This makes it possible to increase the thermal contact area of ​​the heat dissipation portion 164 with the substrate 150, thereby improving heat dissipation.

[0063] In this embodiment, the heat dissipation portion 164 is connected to the side of the screw boss portion 163. Specifically, as shown in FIGS. 4 and 5 , a connection portion 165 is provided between the heat dissipation portion 164 and the screw boss portion 163. The screw boss portion 163, the heat dissipation portion 164, and the connection portion 165 are integrally formed. For example, in a plan view, the corners of the rectangular heat dissipation portion 164 and the side surfaces of the screw boss portion 163 are connected by the connection portion 165. This allows the screw boss portion 163, the heat dissipation portion 164, and the connection portion 165 to have uniform thicknesses. The uniform thickness reduces the occurrence of defects such as sink marks when manufactured by die casting.

[0064] Furthermore, by connecting the heat dissipation portion 164 and the screw boss portion 163, not only the heat dissipation portion 164 but also the screw boss portion 163 can be used as a heat dissipation path. This further improves heat dissipation. The screw boss portion 163 is a necessary portion for fixing the substrate 150 to the case 160 (first divided body 161). Therefore, even if a convex portion with the same height as the screw boss portion 163 is provided as the heat dissipation portion 164, it does not significantly increase the volume of the case 160 (first divided body 161). Furthermore, because the screw boss portion 163 can be used as a heat dissipation path, the volume of the heat dissipation portion 164 itself can be reduced. This allows the case 160 to be made lighter, and therefore the motor unit 100 to be made lighter.

[0065] Furthermore, the reduced volume of the heat dissipation section 164 allows for a larger space within the case 160. This increases the degree of freedom in the layout of the rotation mechanism and other components housed within the case 160. Furthermore, the area in which the board 150 and the case 160 are close to each other also decreases, increasing the space near the board 150. This also increases the degree of freedom in the layout of the electronic components mounted on the board 150.

[0066] Furthermore, at the screw boss portion 163, the screw 190 applies a force that presses the substrate 150 against the screw boss portion 163. As a result, the substrate 150 can apply a force in a direction that crushes the heat dissipation sheet 180 provided between the substrate 150 and the heat dissipation portion 164. This increases the degree of adhesion between the heat dissipation sheet 180 and the substrate 150 and the heat dissipation portion 164, respectively, and strengthens the thermal bond. Specifically, since it is difficult for gaps to form between the heat dissipation sheet 180 and the substrate 150 and the heat dissipation portion 164, heat generated in the power supply IC 170 can be efficiently released to the heat dissipation portion 164. This further improves heat dissipation.

[0067] In this embodiment, the heat dissipation unit 164 and the power supply IC 170 are located away from other heat sources such as the motor 110. Specifically, in a plan view of the substrate 150, the crankshaft 16a, the shaft of the rotating body 141 of the crank rotation sensor unit 140, and the like are located between the heat dissipation unit 164 and the power supply IC 170 and the motor shaft 113. FIG. 3 shows a recess 166 located near the heat dissipation unit 164 and the screw boss portion 163. The recess 166 is a recess into which the shaft of the rotating body 141 of the crank rotation sensor unit 140 is inserted. The crankshaft 16a is also located near the crank rotation sensor unit 140. By locating the heat dissipation unit 164 away from other heat sources, mutual thermal interference can be suppressed, and heat dissipation can be improved.

[0068] In this embodiment, both the screw boss portion 163 and the heat dissipation portion 164 are provided near the outer peripheral wall 167 of the first divided body 161. Specifically, no other protrusions such as bosses are provided between the outer peripheral wall 167 and each of the screw boss portion 163 and the heat dissipation portion 164. In other words, in a plan view of the substrate 150, the power supply IC 170 and the heat dissipation portion 164 are provided on the outer peripheral side within the case 160 (first divided body 161). By providing the heat dissipation portion 164 near the outer peripheral wall 167, heat transferred to the heat dissipation portion 164 can be quickly dissipated via the outer peripheral wall 167. This improves heat dissipation.

[0069] [Summary] The main features of the motor unit 100 and the electric bicycle 1, which is an example of an electric vehicle, described based on the above embodiment will be described below.

[0070] Motor unit 100 according to a first aspect of the present invention is a motor unit used in an electric vehicle, and includes a power supply circuit (power supply IC 170), a substrate 150 on which the power supply circuit is mounted, and a case 160 that houses substrate 150. Case 160 includes a screw boss portion (first convex portion) 163 that protrudes toward substrate 150 and is connected to substrate 150, and a heat dissipation portion (second convex portion) 164 that protrudes toward substrate 150 and is connected to the side of screw boss portion 163.

[0071] This allows not only the heat dissipation portion 164 but also the screw boss portion 163 to be used as a heat dissipation path. Therefore, the volume of the heat dissipation portion 164 can be made smaller than when only the heat dissipation portion 164 is used as a heat dissipation path. This allows the weight of the case 160 to be reduced. Therefore, a lightweight motor unit 100 with high heat dissipation properties can be realized.

[0072] The motor unit 100 according to the second aspect of the present invention is the motor unit according to the first aspect, and in plan view of the substrate 150, the power supply IC 170 and the heat dissipation section 164 overlap each other.

[0073] This shortens the distance between the power supply IC 170 and the heat dissipation section 164 , so that heat generated in the power supply IC 170 can be dissipated quickly via the heat dissipation section 164 .

[0074] The motor unit 100 according to the third aspect of the present invention is a motor unit according to the first or second aspect, and the tip of the screw boss portion 163 is provided with a screw hole (recess) 163a into which a screw (fastening member) 190 for fixing the substrate 150 to the case 160 is inserted.

[0075] This allows not only the heat dissipation portion 164 but also the screw boss portion 163 to be used as a heat dissipation path. Therefore, the volume of the heat dissipation portion 164 can be made smaller than when only the heat dissipation portion 164 is used as a heat dissipation path. This allows the weight of the case 160 to be reduced. Therefore, a lightweight motor unit 100 with high heat dissipation properties can be realized.

[0076] The motor unit 100 according to the fourth aspect of the present invention is a motor unit according to any one of the first to third aspects, in which the distance between the tip 164a of the heat dissipation portion 164 and the substrate 150 is longer than the distance between the screw boss portion 163 and the substrate 150.

[0077] This allows the heat dissipation sheet 180 or the like to be placed in the gap between the tip 164 a of the heat dissipation portion 164 and the substrate 150 .

[0078] The motor unit 100 according to the fifth aspect of the present invention is a motor unit according to any one of the first to fourth aspects, and further comprises a heat dissipation sheet (heat dissipation member) 180 that is arranged between the tip end 164a of the heat dissipation portion 164 and the substrate 150 and is in contact with each of them.

[0079] Thus, by providing the heat dissipation sheet 180, the heat of the substrate 150 can be efficiently propagated to the heat dissipation section 164. Furthermore, because the heat dissipation sheet 180 is disposed near the screw boss section 163, the fastening force of the screw 190 makes it easier for the heat dissipation sheet 180 to adhere to both the heat dissipation section 164 and the substrate 150. Heat generated in the power supply IC 170 can be efficiently dissipated to the heat dissipation section 164, further improving heat dissipation.

[0080] The motor unit 100 according to a sixth aspect of the present invention is a motor unit according to any one of the first to fifth aspects, in which the area of ​​the tip 164a of the heat dissipation portion 164 is larger than the area of ​​the tip of the screw boss portion 163.

[0081] This increases the thermal contact area of ​​the heat dissipation portion 164 with the substrate 150, thereby improving heat dissipation.

[0082] A motor unit 100 according to a seventh aspect of the present invention is the motor unit according to any one of the first to sixth aspects, in which the power supply circuit is an integrated circuit element (power supply IC 170).

[0083] An electric bicycle 1, which is an electric vehicle according to the eighth aspect of the present invention, comprises a motor unit 100 according to any one of the first to seventh aspects, a rear wheel (wheel) 13 to which rotational force from the motor unit 100 is transmitted, and a frame 11 that supports the motor unit 100 and the rear wheel 13.

[0084] This makes it possible to realize an electric bicycle 1 equipped with a motor unit 100 that has high heat dissipation properties and is lightweight.

[0085] (Others) The motor unit and the electric vehicle according to the present invention have been described above based on the above-mentioned embodiment, but the present invention is not limited to the above-mentioned embodiment.

[0086] For example, in the electric bicycle 1, the rotational force of the motor 110 is transmitted to the rear wheel 13, but this is not limitative. The rotational force of the motor 110 may be transmitted to the front wheel 12. Alternatively, the rotational force of the motor 110 may be transmitted to both the front wheel 12 and the rear wheel 13.

[0087] Furthermore, for example, the electric vehicle is not limited to a two-wheeled bicycle. The electric vehicle may be a tricycle with two front wheels and two rear wheels. Alternatively, the electric vehicle may be a bicycle with four or more wheels. Furthermore, the electric vehicle may be a specific small motorized bicycle such as an electric kick scooter.

[0088] Furthermore, for example, the height of the screw boss portion 163 and the height of the heat dissipation portion 164 may be the same. In this case, the heat dissipation sheet 180 may be provided not only between the tip portion 164a of the heat dissipation portion 164 and the substrate 150, but also between the tip portion of the screw boss portion 163 and the substrate 150. For example, the heat dissipation sheet 180 may be provided with a screw hole for inserting the screw 190. Furthermore, the heat dissipation sheet 180 does not have to be provided. Instead of the heat dissipation sheet 180, grease for heat dissipation or the like may be provided. Alternatively, the second main surface 150b of the substrate 150 may be in contact with the tip portion 164a of the heat dissipation portion 164.

[0089] Furthermore, the heat dissipation section 164 and the power supply IC 170 do not have to overlap in a plan view of the substrate 150. For example, the power supply IC 170 may be provided so that at least a portion of the power supply IC 170 falls within a predetermined circular range centered on the heat dissipation section 164 in a plan view of the substrate 150. The predetermined circular range is, for example, a circular range inscribed with the screw boss section 163 and centered on the heat dissipation section 164, but is not limited to this.

[0090] Furthermore, the first convex portion connected to the substrate 150 may be a convex portion other than the screw boss portion 163. For example, the first convex portion may be connected to the substrate 150 by fitting a part of the substrate 150 therein. Specifically, the substrate 150 may be provided with a protrusion that protrudes toward the first convex portion, and the protrusion may be fitted into a recess or a through-hole provided in the first convex portion. Furthermore, an adhesive may be provided at the tip of the first convex portion, and the first convex portion and the substrate 150 may be connected via the adhesive. In this way, the first convex portion connected to the substrate 150 may be a convex portion that is used to fix and position the substrate 150, and the specific connection mode is not particularly limited.

[0091] The first protrusion may be a protrusion provided on the case 160, and may be a screw boss for fixing a component other than the substrate 150. Alternatively, the first protrusion may be a protrusion provided on the case 160 so that the case 160 can support a component housed therein.

[0092] Furthermore, the fastening members for fixing the substrate 150 to the case 160 are not limited to screws. For example, the fastening members may be a combination of bolts and nuts.

[0093] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the present invention.

[0094] REFERENCE SIGNS LIST 1 Electric bicycle (electric vehicle) 11 Frame 12 Front wheel (wheel) 13 Rear wheel (wheel) 100 Motor unit 110 Motor 150 Circuit board 160 Case 163 Screw boss portion (first convex portion) 163a Screw hole (concave portion) 164 Heat dissipation portion (second convex portion) 164a Tip portion 170 Power supply IC (power supply circuit) 180 Heat dissipation sheet (heat dissipation member) 190 Screw (fastening member)

Claims

1. A motor unit for use in an electric vehicle, comprising: a power supply circuit; a board on which the power supply circuit is mounted; a case that houses the board; and the case including: a first convex portion that protrudes toward the board and is connected to the board; and a second convex portion that protrudes toward the board and is connected to a side of the first convex portion.

2. The motor unit according to claim 1, wherein the power supply circuit and the second protrusion overlap in a plan view of the substrate.

3. The motor unit according to claim 2, wherein the tip of the first protrusion is provided with a recess into which a fastening member for fixing the circuit board to the case is inserted.

4. A motor unit according to any one of claims 1 to 3, wherein the distance between the tip of the second protrusion and the substrate is longer than the distance between the first protrusion and the substrate.

5. The motor unit according to claim 4, further comprising a heat dissipation member disposed between the tip of the second protrusion and the substrate and in contact with each other.

6. A motor unit according to any one of claims 1 to 3, wherein the area of ​​the tip of the second protrusion is larger than the area of ​​the tip of the first protrusion.

7. The motor unit according to any one of claims 1 to 3, wherein the power supply circuit is an integrated circuit element.

8. An electric vehicle comprising: a motor unit according to any one of claims 1 to 3; a wheel to which rotational force from said motor unit is transmitted; and a frame supporting said motor unit and said wheel.

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