Motor unit for electric bicycle and electric bicycle

Abstract

To provide a motor unit for electric bicycles that can improve heat dissipation.SOLUTION: A motor unit for electric bicycles 3 includes a motor 5 having a stator 53, a rotor 54, and a rotating shaft 51, a unit case 4 in which part of the rotating shaft 51 is housed, a control board 35 housed in the unit case 4 and controlling the rotation of the motor 5, and a thermally conductive member 9 in contact with the control board 35 and the unit case 4 to conduct heat from the control board 35 to the unit case 4. The thermally conductive member 9 has a first thermally conductive member 91 provided between the control board 35 and the stator 53.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a motor unit for an electric bicycle and an electric bicycle equipped with the same.

Background Art

[0002] Patent Document 1 describes an electric bicycle (electric assist bicycle) equipped with a motor unit. In this motor unit, a motor is housed in a unit case serving as an outer shell. The unit case includes a motor case for housing the motor. This motor case is integrally resin-molded with the stator of the motor using a molding technique.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described conventional motor unit, there is room for improvement in the heat dissipation of the heat generated by the drive of the motor.

[0005] An object of the present invention is to provide a motor unit for an electric bicycle capable of improving heat dissipation and an electric bicycle equipped with the same.

Means for Solving the Problems

[0006] A motor unit for an electric bicycle according to an aspect of the present invention includes a motor and a unit case to which the motor is attached. The motor includes a stator, a rotor positioned surrounded by the stator, a rotating shaft fixed to the rotor, and a metal cup having an opening and housing at least a part of the stator and the rotor. The inner peripheral surface of the metal cup is in pressure contact with the stator.

[0007] An electric bicycle according to one aspect of the present invention comprises an electric bicycle motor unit according to the aforementioned aspect and a wheel to which the rotational force of the motor of the electric bicycle motor unit is transmitted.

[0008] A motor unit for an electric bicycle according to another aspect of the present invention comprises a motor having a rotating shaft, a unit case housing a part of the rotating shaft, an input shaft disposed in the unit case so as to penetrate the unit case and rotatable about an axis, an input body disposed along the outer circumferential surface of the input shaft and rotating integrally with the input shaft, an output body disposed along the outer circumferential surface of the input shaft and rotating about the axis in response to the rotational force of the input body, and a control board housed in the unit case and controlling the rotation of the motor. The unit case has a first heat dissipation section connected to a first surface of the control board and a second heat dissipation section connected to a second surface of the control board opposite to the first surface.

[0009] An electric bicycle according to another aspect of the present invention comprises an electric bicycle motor unit according to the above-mentioned other aspect and a wheel to which the rotational force of the motor of the electric bicycle motor unit is transmitted. [Effects of the Invention]

[0010] The present invention has the effect of providing an electric bicycle motor unit that can achieve improved heat dissipation, and an electric bicycle equipped therewith. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a side view of an electric bicycle according to one embodiment. [Figure 2] Figure 2A is a side view of the motor unit of the electric bicycle described above, and Figure 2B is a perspective view of the same motor unit. [Figure 3] Figure 3 is a cross-sectional view taken along line AA in Figure 2A. [Figure 4]Figure 4 is an exploded perspective view of the main components of the motor unit shown above. [Figure 5] Figure 5 is an exploded perspective view of another key part of the same motor unit. [Figure 6] Figure 6 is a side view of the metal cup of the motor unit shown above. [Figure 7] Figure 7 is a cross-sectional view of a modified example 1 of the motor unit described above. [Figure 8] Figure 8 is a cross-sectional view of a modified example 2 of the motor unit shown above. [Figure 9] Figure 9 is a cross-sectional view of a modified example 3 of the motor unit described above. [Modes for carrying out the invention]

[0012] (One embodiment) One embodiment of the electric bicycle 1 is an electric assist bicycle. One embodiment of the electric bicycle 1 comprises a frame 10, an electric bicycle motor unit 3 (hereinafter simply referred to as "motor unit 3") fixed to the frame 10, and two wheels 11 rotatably connected to the frame 10. The two wheels 11 are a front wheel 111 and a rear wheel 112. Of these, the rear wheel 112 is rotationally driven by the driving force output from the motor unit 3.

[0013] In this text, the directions of forward, backward, left, and right are defined relative to the driver of the electric bicycle 1. That is, the direction in which the driver is moving on the electric bicycle 1 is forward, the opposite direction is backward, the left direction is to the left from the driver's perspective, and the right direction is to the right from the driver's perspective. The following describes each component in detail.

[0014] First, let's explain frame 10.

[0015] As shown in Figure 1, the frame 10 has a head pipe 101, an upper pipe 102, a lower pipe 103, a vertical pipe 104, a seat stay 105, a chain stay 106, and a bracket 2.

[0016] The frame 10 (that is, each of the above-mentioned parts constituting the frame 10) is formed of a metal such as aluminum or stainless steel, but may partially contain a non-metal. The entire frame 10 may be formed of a non-metal, and the material of the frame 10 is not particularly limited.

[0017] A handle post 12 is rotatably inserted into the head pipe 101. A front fork 121 is formed at the lower end of the handle post 12. A front wheel 111 is rotatably attached to the front fork 121. A handlebar 122 is fixed to the upper end of the handle post 12.

[0018] The front end of the upper pipe 102 is fixed to the head pipe 101. The rear end of the upper pipe 102 is fixed to the upright pipe 104. A pipe 132 extending downward from the saddle 13 is inserted into the upper end opening of the upright pipe 104. By fixing this pipe 132 to the upright pipe 104, the saddle 13 is fixed. A bracket 2 is fixed to the lower end of the upright pipe 104.

[0019] The front end of the lower pipe 103 is further fixed to the head pipe 101. The rear end of the lower pipe 103 is fixed to the bracket 2.

[0020] A motor unit 3 is fixed below the bracket 2. The front end of a chain stay 106 is fixed to the rear end of the bracket 2.

[0021] The front end of a seat stay 105 is fixed to the rear end of the upper pipe 102. The rear end of the seat stay 105 is connected to the rear end of the chain stay 106, and a rear wheel 112 is rotatably mounted at this connection part. A battery 15 for supplying power to the motor unit 3 is detachably mounted on the lower pipe 103.

[0022] Next, the motor unit 3 will be described.

[0023] As shown in Figures 2A and 2B, the majority of the outer shell of the motor unit 3 is formed by the unit case 4. As shown in Figure 3, the motor 5, which is the drive source for rotating the wheel 11, is mounted in the unit case 4. In addition to the reduction mechanism 31 to which the rotational force of the motor 5 is transmitted and the control board 35 that controls the rotation of the motor 5, the unit case 4 also houses the input shaft 6, input body 7, output body 8, etc.

[0024] A bottomed cylindrical metal cup 57, which houses the main part of the motor 5, is attached to the outer surface of the unit case 4. The metal cup 57 has an opening, and the opening edge 574 of the metal cup 57 is connected to the unit case 4.

[0025] The portion of the motor 5 that is not housed in the metal cup 57 (for example, a part of the rotating shaft 51 described later) is housed in the unit case 4. Multiple first mounting pieces 401, which are fixed to the bracket 2, and multiple second mounting pieces 402, which are also fixed to the bracket 2, protrude from the outer surface of the unit case 4.

[0026] The unit case 4 includes a first segment 41 that forms the left half of the unit case 4 and a second segment 42 that forms the right half of the unit case 4. Multiple first mounting pieces 401 protrude from the first segment 41, and multiple second mounting pieces 402 protrude from the second segment 42. The first segment 41 and the second segment 42 are combined to form the hollow unit case 4.

[0027] As shown in Figures 3 and 4, the first segment 41 has a space that opens to the right. This space constitutes the left half of the storage space of the unit case 4. The first segment 41 has a wall portion 415 in the part facing the motor 5. The wall portion 415 has a circular through hole 412 and an arc-shaped through hole 413 that is concentric with it. A part of the motor 5 (the rotating shaft 51 described later) is inserted through the through hole 412. The power supply path to the motor 5 and the resin portion in which it is molded are inserted through the through hole 413.

[0028] The second segment 42 has a space that is open to the left. This space constitutes the right half of the storage space of the unit case 4. The first segment 41 and the second segment 42 are fixed to each other so that their respective spaces are in communication.

[0029] The metal cup 57 of the motor 5 integrally comprises a circular bottom wall 572, a peripheral wall 573 extending from the periphery of the bottom wall 572, and a flange-shaped opening edge 574 formed at the tip of the peripheral wall 573 (see Figures 5 and 6). The peripheral wall 573 extends along the thickness direction of the bottom wall 572.

[0030] The metal cup 57 is made of aluminum (aluminum die-cast), but the material of the metal cup 57 is not limited to this, and may be made of iron, magnesium alloy, titanium, etc.

[0031] The annular opening edge 574 has multiple screw holes 575 located at intervals in the circumferential direction, multiple projections 576 also located at intervals in the circumferential direction, and an annular groove 577 (see Figure 6).

[0032] The multiple screw holes 575 are screw holes for fastening multiple screw fittings 571 one-to-one. The multiple protrusions 576 are projections that fit into recesses on the outer surface of the first segmented body 41 to position the metal cup 57. The groove 577 is a groove for positioning the O-ring 49 and is formed around the entire circumference of the opening edge 574.

[0033] The groove 577 is located radially inward (closer to the opening of the metal cup 57) than the multiple screw holes 575 and multiple protrusions 576. The outer shape of the groove 577 is not perfectly circular, and in the portion where the screw holes 575 and protrusions 576 are located, it is bent radially inward (see Figure 6). As a result, in one embodiment of the motor unit 3, the outer diameter of the opening edge 574 of the metal cup 57 is reduced, but it is also possible to form the outer shape of the groove 577 to be perfectly circular.

[0034] To fix the metal cup 57 to the outer surface of the first divided body 41, multiple screw fasteners 571 are inserted through the opening of the first divided body 41 (see Figure 4), and each screw fastener 571 is fastened through the first divided body 41 into the corresponding screw hole 575. As a result, the opening edge 574 of the metal cup 57 is hermetically fixed to the outer surface of the first divided body 41 via the elastic O-ring 49. The interposition of the O-ring 49 between the metal cup 57 and the unit case 4 also provides the effect of suppressing vibration transmission.

[0035] As shown in Figure 3, the motor 5 has a cylindrical rotating shaft 51, a rotor 52 coupled to the rotating shaft 51 so as to rotate integrally with the rotating shaft 51, and a cylindrical stator 53 positioned surrounding the rotor 52.

[0036] The metal cup 57 houses a portion of the motor 5's rotating shaft 51 in the axial direction (the axial half of the rotating shaft 51), the rotor 52, and a portion of the stator 53 (the majority of the stator 53). The remaining portion of the rotating shaft 51 (the remaining axial half of the rotating shaft 51) and the remaining portion of the stator 53 (the resin-molded portion of the stator 53) protrude from the opening of the metal cup 57.

[0037] A recess 578 for accommodating a bearing 552 is formed on the inner surface of the bottom wall 572 of the metal cup 57. The bearing 552 is a bearing that rotatably supports the axial end of the rotating shaft 51. The other axial end of the rotating shaft 51 is rotatably supported by a bearing 551 located in a recess 428 on the inner surface of the second divided body 42.

[0038] The outer circumferential surface of the portion of the rotating shaft 51 that protrudes from the metal cup 57 has teeth 54 formed on it for engaging with the reduction mechanism 31.

[0039] In one embodiment of the motor unit 3, the inner circumferential surface 570 of the metal cup 57 (i.e., the inner circumferential surface of the metal peripheral wall 573) is firmly pressed against the outer circumferential surface 530 of the stator 53 over its entire circumference. Here, the inner circumferential surface 570 of the metal cup 57 being pressed against the stator 53 means that the inner circumferential surface 570 of the metal cup 57 is in contact with the stator 53 with pressure. A pressure acting between the inner circumferential surface 570 of the metal cup 57 and the outer circumferential surface 530 of the stator 53 is acting in a radial direction, pushing them against each other.

[0040] More specifically, the metal cup 57 is shrink-fitted to the stator 53. That is, the metal cup 57 expands due to heating and is fitted onto the stator 53, and then contracts as the temperature drops, causing the metal cup 57 to press firmly against the stator 53. The inner circumferential surface 570 of the metal cup 57 is a metal surface that is connected to an annular shape. The inner circumferential surface 570 of the metal cup 57 is in close contact with the outer circumferential surface 530 of the stator 53 under pressure along its entire circumference.

[0041] The portion of the outer surface 530 of the stator 53 that is not resin-molded is the metal surface 535. The stator 53 is not entirely resin-molded, but is partially resin-molded so that at least the metal surface 535 is exposed on the outer surface. The metal surface 535 is the outer surface of the iron core 533 of the stator 53. The coil 534 wound around the iron core 533 is covered with resin molding.

[0042] Thus, in the motor unit 3 of one embodiment, the stator 53 is resin-molded (partially molded) except for a portion. This portion includes the part of the stator 53 that is pressed against the inner circumferential surface 570 of the metal cup 57 (i.e., the outer circumferential surface 530 of the stator 53).

[0043] Therefore, the heat generated inside the motor 5 is directly transferred from the stator 53 to the metal cup 57 and efficiently dissipated to the outside air through the metal cup 57. The surface of the metal cup 57 can be exposed to the airflow while driving. Note that, as will be shown in the modified examples described later, the resin molding in the stator 53 is not essential.

[0044] As shown in Figure 5, a rotation-preventing pin 48 is positioned between the metal cup 57 and the stator 53. A straight groove 538 is formed on the outer circumferential surface 530 of the stator 53 so that a portion of the pin 48 fits into it. A straight groove 579 is formed on the inner circumferential surface 570 of the metal cup 57 so that another portion of the pin 48 fits into it (see Figure 6).

[0045] The pin 48 is positioned parallel to the axial direction of the motor 5 (i.e., the axial direction of the rotation axis 51). By fitting the pin 48 between the metal cup 57 and the stator 53, the relative rotation of the metal cup 57 and the stator 53 is more firmly suppressed.

[0046] Incidentally, in one embodiment of the motor unit 3, the stator 53 includes a portion 531 that protrudes through the opening of the metal cup 57 (see Figure 4). In the axial direction of the motor 5, this portion 531 of the stator 53 protrudes toward the side opposite to the side where the bottom wall 572 of the metal cup 57 is located. This portion 531 also functions as a guide when the O-ring 49 is fitted.

[0047] Up to this point, we have mainly described the structure of the motor 5. Next, we will describe the various mechanisms housed in the unit case 4.

[0048] As shown in Figure 3, the unit case 4 houses the input shaft 6 so as to be rotatable around its axis 60. The first divided body 41 has a through hole 411 through which the input shaft 6 is inserted. The second divided body 42 has a through hole 421 through which the input shaft 6 is inserted.

[0049] Crank arms 18 are fixed to both ends of the input shaft 6. Pedals 181 are rotatably attached to the ends of the crank arms 18 (see Figure 1). The driver can apply human-powered rotational force to the input shaft 6 by pedaling the pedals 181.

[0050] Within the unit case 4, the input body 7 is positioned along the outer circumferential surface of the input shaft 6. The input body 7 is a cylindrical member and rotates integrally with the input shaft 6.

[0051] The input body 7 is divided into a first input body 71 and a second input body 72. The first input body 71 is connected to the input shaft 6 within the first divided body 41. The second input body 72 is connected to the first input body 71 within the second divided body 42 and transmits rotational force to the output body 8.

[0052] The output unit 8 is a cylindrical member and is rotatably positioned along the outer circumferential surface of the input shaft 6. One end of the output unit 8 protrudes out of the unit case 4 through the through hole 421 of the second divided body 42.

[0053] The front sprocket 191 is fixed to the portion of the output unit 8 that protrudes from the unit case 4. The front sprocket 191 rotates integrally with the output unit 8. The rear sprocket 192 is fixed to the hub of the rear wheel 112 (see Figure 1). A chain 193 is routed between the front sprocket 191 and the rear sprocket 192.

[0054] As shown in Figure 3, a one-way clutch 32 is positioned inside the unit case 4 between the input body 7 and the output body 8. The one-way clutch 32 is configured to transmit rotational force in the acceleration direction to the output body 8 when a rotational force in the acceleration direction is applied to the input body 7, and to block the transmission of rotational force to the output body 8 when a rotational force in the deceleration direction is applied to the input body 7. Here, the acceleration direction means the direction in which the electric bicycle 1 is accelerated in the direction of travel. The deceleration direction is the opposite direction to the acceleration direction.

[0055] The output unit 8 integrally comprises a web 81 and a rim 82. The web 81 protrudes radially outward from the output unit 8. The rim 82 is continuous with the radially outer end of the web 81. Teeth 83 that engage with the reduction mechanism 31 are formed on the outer circumferential surface of the rim 82.

[0056] The reduction mechanism 31 housed in the unit case 4 is configured to reduce the rotation of the motor 5 and transmit it to the output unit 8.

[0057] The reduction gear 31 includes a rotating shaft 310 and a first transmission gear 311 and a second transmission gear 312 supported by the rotating shaft 310.

[0058] The first transmission gear 311 is a cylindrical member that receives rotational force from the rotating shaft 51 of the motor 5. Teeth 313 that mesh with the teeth 54 of the rotating shaft 51 are formed on the outer circumferential surface of the first transmission gear 311.

[0059] The rotating shaft 310 is rotatably housed in the unit case 4 with its axial direction being the left-right direction. One end of the rotating shaft 310 is rotatably supported by a bearing 314 located in the second divided body 42.

[0060] The first transmission gear 311 is connected to the rotating shaft 310 via a one-way clutch 315.

[0061] The one-way clutch 315 is configured to transmit rotational force to the rotating shaft 310 when an acceleration rotational force is applied to the first transmission gear 311, and to block the transmission of rotational force to the rotating shaft 310 when a deceleration rotational force is applied to the first transmission gear 311.

[0062] The second transmission gear 312 is fixed so as to rotate integrally with the rotating shaft 310. The second transmission gear 312 transmits the rotational force transmitted from the first transmission gear 311 via the rotating shaft 310 to the teeth 83 of the output body 8. Teeth 316 that mesh with the teeth 83 are formed on the outer circumferential surface of the second transmission gear 312.

[0063] In one embodiment, the motor unit 3 has the above configuration, so when the driver pedals the electric bicycle 1 and the input shaft 6 rotates in the acceleration direction, the first input body 71 and the second input body 72 rotate together with the input shaft 6. When the rotational force of the second input body 72 in the acceleration direction is transmitted to the output body 8 via the one-way clutch 32, the output body 8 and the front sprocket 191 rotate in the acceleration direction. When the front sprocket 191 rotates in the acceleration direction, the rear sprocket 192 rotates in the acceleration direction via the chain 193, and the rear wheel 112 is driven to rotate in the acceleration direction.

[0064] Furthermore, in the motor unit 3 of one embodiment, it is possible to apply the rotational force output from the motor 5 to the output body 8, as will be explained below.

[0065] When the rotating shaft 51 of the motor 5 rotates in the acceleration direction, the first transmission gear 311, which meshes with the rotating shaft 51, also rotates in the acceleration direction. The rotational force of the first transmission gear 311 in the acceleration direction is transmitted to the rotating shaft 310 and the second transmission gear 312 via the one-way clutch 315, causing the second transmission gear 312 to rotate in the acceleration direction. The rotational force of the second transmission gear 312 in the acceleration direction is transmitted to the output unit 8. The output unit 8 receives a combination of the rotational force from the motor 5 and the rotational force generated by the driver pedaling the pedal 181.

[0066] In one embodiment of the electric bicycle 1, a control unit on the control board 35 controls the rotation of the motor 5 according to the torque applied to the input shaft 6 and the rotational speed of the input shaft 6 per unit time. The torque applied to the input shaft 6 is detected by a torque detector 33 housed in a unit case 4. The torque detector 33 is a magnetostrictive torque detector comprising a magnetostrictive generating section 331 formed on the outer circumferential surface of the first input body 71 and a coil 332 positioned at a small distance from the magnetostrictive generating section 331.

[0067] The rotational speed of the input shaft 6 per unit time is detected by the rotation detector 34. The rotation detector 34 is an optical rotation detector comprising a rotating body 341 that rotates integrally with the input body 7 and a light sensor 342 positioned at a small distance from the rotating body 341.

[0068] The control unit of the control board 35, for example, has a microcomputer and controls the operation of each element by executing a program stored in a storage unit such as a ROM (Read Only Memory). A known control unit can be used as appropriate.

[0069] In one embodiment, the motor unit 3 has the above configuration, so that the heat from the stator 53 is directly transferred to the metal cup 57 through the metal surface 535, and the heat is efficiently dissipated from the outer surface of the metal cup 57. In addition, since the amount of resin used is reduced, the entire motor unit 3 is made lighter.

[0070] (modified version) Next, various modifications of the motor unit 3 and electric bicycle 1 according to one embodiment will be described. In the various modifications described below, components that are the same as those already described will be denoted by the same reference numerals and their detailed descriptions will be omitted.

[0071] Figure 7 shows a cross-section of Modification 1 of the motor unit 3. In the motor unit 3 shown in Figure 3, etc., the stator 53 is partially molded in resin, but in Modification 1 of the motor unit 3, the stator 53 is not molded in resin.

[0072] In other words, neither the iron core 533 of the stator 53 nor the coil 534 wound around it are resin-molded. The metal surface 535 formed on the outer surface of the iron core 533 and the inner surface 570 of the metal cup 57 are in close contact with each other under mutual pressure.

[0073] In Modification 1, the stator 53 is not resin-molded, so the entire motor 5 is further lightened. In contrast, if the stator 53 is resin-molded except for the metal surface 535, there are advantages such as the rapid temperature rise of the stator 53 being suppressed by the heat retention properties of the resin part, the resin part exhibiting vibration suppression and noise suppression functions, and the insulation between the coil 534 and the metal cup 57 being improved by the resin part.

[0074] Figure 8 shows a cross-section of Modification 2 of the motor unit 3. While the motor unit 3 shown in Figure 3, etc., is a so-called single-axis motor unit, Modification 2 of the motor unit 3 is a double-axis motor unit 3.

[0075] In modified example 2, the motor unit 3 includes a second output unit 310B that is different from the output unit 8.

[0076] The first end of the second output unit 310B is located inside the unit case 4. The second output unit 310B is rotatably supported by a bearing 3191B located on the first segment 41 and a bearing 3192B located on the second segment 42.

[0077] The second end of the second output unit 310B protrudes outside the unit case 4. A sprocket 194B is fixed to the second end of the second output unit 310B. A chain 193 is attached to the sprocket 194B.

[0078] A large-diameter gear 318B is attached to the outer surface of the second output unit 310B via a one-way clutch 317B. The gear 318B meshes with the teeth 54 of the rotating shaft 51 of the motor 5.

[0079] In the electric bicycle 1 equipped with a modified example 2 of the motor unit 3, when the driver pedals 181 and the motor 5's rotating shaft 51 rotates in the acceleration direction, the gear 318B rotates in the acceleration direction, and this rotational force is transmitted to the second output unit 310B via the one-way clutch 317B, and further transmitted to the chain 193.

[0080] Next, a third modified example of the motor unit 3 will be described based on Figure 9.

[0081] In Modification 3, the first segment 41 of the unit case 4, which is made of metal, integrally includes a first heat dissipation section 414. In Modification 3, a portion of the first segment 41 is formed to be thicker than the surrounding portion, and this thicker portion constitutes the first heat dissipation section 414 made of metal that protrudes inward from the unit case 4.

[0082] The first heat dissipation section 414 is connected to the first surface 351 in the thickness direction of the control board 35 via a first thermal conductive sheet 91, which is a thermal conductive member 9. The concept of connection used in this text includes not only direct contact without other members, but also indirect connections via other members.

[0083] The thickness direction of the control board 35 is the thickness direction of the printed circuit board 354 on which the control board 35 is located, and in the modified example 3, it is the left-right direction. The first surface 351 of the control board 35 is the main body of one surface in the thickness direction of the printed circuit board 354. The second surface 352 of the control board 35 is the main body of the other surface in the thickness direction of the printed circuit board 354.

[0084] The control board 35 further includes a plurality of electrical components 353 mounted on the printed circuit board 354. These electrical components 353 include, for example, capacitors 3532, integrated circuits (Hall ICs) 3533, and especially heat-generating elements 3531. The heat-generating elements 3531 are, for example, switching elements such as FETs that supply power to the motor 5, diodes, coils, etc. Other electrical components 353 may include various resistors, connectors, etc.

[0085] The second segment 42 of the unit case 4 integrally includes a second heat dissipation section 424. In modified example 3, a part of the second segment 42 is formed to be recessed inward compared to the surrounding part, and the bottom of this recessed portion constitutes a metal second heat dissipation section 424 that protrudes inward from the unit case 4.

[0086] The second heat dissipation section 424 is connected to the second surface 352 of the control board 35 via a second heat conductive sheet 92, which is a heat conductive member 9. The second surface 352 is the surface facing the opposite side from the first surface 351.

[0087] Multiple heat-generating elements 3531 are in contact with the second thermal conductive sheet 92. The heat generated by the multiple heat-generating elements 3531 is efficiently dissipated from the outer surface of the unit case 4 via the second thermal conductive sheet 91 and the second heat dissipation section 424.

[0088] The number of heating elements 3531 in contact with the second thermal conductive sheet 91 is not limited to multiple; it may be just one. Furthermore, one or more heating elements 3531 may be in contact with the first thermal conductive sheet 91, or one or more heating elements 3531 may be in contact with both the first thermal conductive sheet 91 and the second thermal conductive sheet 92.

[0089] As described above, in the modified example 3, the first heat dissipation section 414, which is integrally formed with the unit case 4, is connected to the first surface 351 of the control board 35, and the second heat dissipation section 424, which is integrally formed with the unit case 4, is connected to the second surface 352 of the control board 35. The heat from the control board 35 (for example, the heat generated by the heat-generating element 3531) is efficiently dissipated from both sides in the thickness direction, thereby improving the heat dissipation performance of the electric bicycle motor unit 3.

[0090] In addition, the improved heat dissipation of the control board 35 allows for a narrower spacing between the multiple heat-generating elements 3531 mounted on the printed circuit board 354, thereby enabling miniaturization of the control board 35.

[0091] As shown in Figure 9, in the modified example 3, when viewed in the thickness direction (i.e., left-right direction) of the control board 35, both the first heat dissipation section 414 and the second heat dissipation section 424 are located in positions that overlap with the heat-generating element 3531. Therefore, the heat generated by the heat-generating element 3531 is efficiently dissipated through the first heat dissipation section 414 and the second heat dissipation section 424. It is sufficient that at least a portion of the first heat dissipation section 414 and the second heat dissipation section 424 overlaps with the heat-generating element 3531.

[0092] As shown in Figure 9, when viewed in the thickness direction of the control board 35, the first heat dissipation section 414 is located in a position that overlaps with the second heat dissipation section 424. In the modified example 3, a part of the control board 35 (specifically, the edge of the control board 35 that is away from the input shaft 6) is sandwiched from both sides by the first heat dissipation section 414 and the second heat dissipation section 424. This improves heat dissipation, as well as the reliability of fixing the control board 35 and the vibration resistance of the motor unit 3. The first heat dissipation section 414 only needs to be located in a position that overlaps with the second heat dissipation section 424 in at least a portion of it.

[0093] In modified example 3, the thermal conductive member 9 includes a first thermal conductive sheet 91 and a second thermal conductive sheet 92, but it is also possible that the thermal conductive member 9 does not include either the first thermal conductive sheet 91 or the second thermal conductive sheet 92.

[0094] If the thermal conductive member 9 does not include the first thermal conductive sheet 91, the first heat dissipation section 414 is in direct contact with the first surface 351 of the control board 35. If the thermal conductive member 9 does not include the second thermal conductive sheet 92, the second heat dissipation section 424 is in direct contact with the second surface 352 of the control board 35.

[0095] Furthermore, in Modification 3, the first thermal conductive sheet 91 and the second thermal conductive sheet 92 are formed from different sheet materials, but the first thermal conductive sheet 91 and the second thermal conductive sheet 92 may be formed from the same sheet material. In other words, a portion of the sheet material constituting the thermal conductive member 9 may constitute the first thermal conductive sheet 91, and another portion of the sheet material may constitute the second thermal conductive sheet 92.

[0096] The above-described modifications 1 to 3 are merely a few of many possible modifications. The metal cup 57 only needs to house at least a portion of the stator 53 and rotor 52. In one embodiment and its modifications 1 to 3, a portion of the stator 53 protrudes from the opening of the metal cup 57, but the entire stator 53 may be housed in the metal cup 57. In one embodiment and its modifications 1 to 3, the electric bicycle equipped with the motor unit 3 is a so-called electric assist bicycle, but it is not limited to this, and may be an electric bicycle that can rotate the wheels 11 using only the rotational force of the motor 5. Also, in one embodiment and its modifications 1 to 3, the electric bicycle has two wheels 11, but the number of wheels 11 is not particularly limited, and for example, it may have three wheels 11.

[0097] Furthermore, in the embodiment and its modifications 1 to 3, the metal cup 57 and the stator 53 are fixed using a shrink-fitting method, but adhesive may also be interposed between the metal cup 57 and the stator 53 (for example, between the inner circumferential surface 570 of the metal cup 57 and the outer circumferential surface 530 of the stator 53). In other words, in order to fix the metal cup 57 and the stator 53, in addition to fixing by shrink-fitting, fixing with adhesive may also be performed. Alternatively, the metal cup 57 and the stator 53 may be pressed together by a method other than shrink-fitting (for example, a press-fitting method), and fixing with adhesive may also be performed in addition to this.

[0098] (Appearance) As is clear from the description of the above embodiment and various modifications thereof, the motor unit (3) for an electric bicycle according to the first embodiment comprises a motor (5) and a unit case (4) to which the motor (5) is mounted. The motor (5) comprises a stator (53), a rotor (52) located surrounded by the stator (53), a rotating shaft (51) fixed to the rotor (52), and a metal cup (57) that houses at least a portion of the stator (53) and rotor (52). The metal cup (57) has an opening. The inner circumferential surface (570) of the metal cup (57) is in contact with the stator (53).

[0099] In the first embodiment of the electric bicycle motor unit (3), heat from the stator (53) is transferred to the metal cup (57) pressed against it, and the heat is efficiently dissipated through the metal cup (57). Therefore, the heat dissipation performance of the electric bicycle motor unit (3) can be improved. In addition, the adoption of the metal cup (57) in the first embodiment of the electric bicycle motor unit (3) enables further weight reduction.

[0100] The motor unit (3) for electric bicycles according to the second embodiment is realized by combining it with the first embodiment. In the motor unit (3) for electric bicycles according to the second embodiment, at least a portion of the outer circumferential surface (530) of the stator (53) is a metal surface (535). The inner circumferential surface (570) of the metal cup (57) is in pressure contact with the metal surface (535).

[0101] In the motor unit for electric bicycles (3) of the second embodiment, the inner circumferential surface (570) of the metal cup (57) is pressed against a metal surface (535) that is relatively easy to achieve precision with and conducts heat well, so heat is easily transferred between the metal cup (57) and the stator (53), and high heat dissipation is obtained.

[0102] The motor unit (3) for electric bicycles according to the third embodiment is realized by combination with the first or second embodiment. In the motor unit (3) for electric bicycles according to the third embodiment, the stator (53) is resin-molded except for a portion. This portion includes the part of the stator (53) that is pressed against the metal cup (57).

[0103] In the third embodiment of the electric bicycle motor unit (3), the rapid temperature rise of the stator 53 is suppressed by partial resin molding, and vibration is also suppressed by the resin molding. Furthermore, the partial resin molding enhances the insulation between the stator (53) and the metal cup (57).

[0104] The motor unit (3) for electric bicycles according to the fourth embodiment is realized by combining it with any one of the first to third embodiments. The motor unit (3) for electric bicycles according to the fourth embodiment further comprises a reduction mechanism (31) to which the rotational force of the motor (5) is transmitted, and the reduction mechanism (31) is housed in the unit case (4).

[0105] In the motor unit (3) for electric bicycles of the fourth embodiment, the motor (5) and the reduction mechanism (31) that transmits its rotational force are integrated into a single unit.

[0106] The motor unit (3) for electric bicycles according to the fifth embodiment is realized by combining it with the fourth embodiment. The motor unit (3) for electric bicycles according to the fifth embodiment further comprises an O-ring (49) interposed between the unit case (4) and the metal cup (57). The metal cup (57) has an open edge (574) against which the O-ring (49) presses.

[0107] In the motor unit (3) for electric bicycles according to the fifth embodiment, the O-ring (49) can improve the airtightness between the metal cup (57) and the unit case (4), and can also suppress the transmission of vibrations.

[0108] The motor unit for electric bicycles (3) of the sixth embodiment is realized by combining with the fifth embodiment. In the motor unit for electric bicycles (3) of the sixth embodiment, the stator (53) includes a portion (531) that protrudes from the metal cup (57) through an opening.

[0109] In the sixth embodiment of the electric bicycle motor unit (3), the portion (531) of the stator (53) that protrudes from the metal cup (57) functions as a guide when attaching the O-ring (49).

[0110] The motor unit for electric bicycles (3) of the seventh embodiment is realized by combining it with any one of the first to sixth embodiments. In the motor unit for electric bicycles (3) of the sixth embodiment, the metal cup (57) is shrink-fitted to the stator (53).

[0111] In the motor unit for electric bicycles (3) of the seventh embodiment, the metal cup (57) can be firmly pressed against the stator (53).

[0112] The motor unit (3) for electric bicycles according to the eighth embodiment is realized by combining it with any one of the first to seventh embodiments. In the motor unit (3) for electric bicycles according to the eighth embodiment, the motor (5) further comprises a bearing (552) that rotatably supports a rotating shaft (51). A recess (578) for arranging the bearing (552) is formed in a part of the metal cup (57).

[0113] In the motor unit for electric bicycles (3) of the eighth embodiment, the structure for arranging the bearing (552) can be made of a part of the metal cup (57), thereby achieving further weight reduction.

[0114] The electric bicycle (1) of the ninth embodiment comprises an electric bicycle motor unit (3) of any one of the first to eighth embodiments and a wheel (11) to which the rotational force of the motor (5) of the electric bicycle motor unit (3) is transmitted.

[0115] In the electric bicycle (1) of the ninth embodiment, improved heat dissipation of the electric bicycle motor unit (3) can be achieved. In addition, the electric bicycle (1) of the ninth embodiment can be made lighter.

[0116] Furthermore, as is clear from the description of the above embodiment and various modifications thereof (particularly modification 3), the motor unit (3) for electric bicycles of the tenth embodiment comprises a motor (5) having a rotating shaft (51), a unit case (4) in which a part of the rotating shaft (51) is housed, an input shaft (6) arranged in the unit case (4) so ​​as to penetrate the unit case (4) and rotatable about an axis (60), an input body (7) arranged along the outer circumferential surface of the input shaft (6) and rotating integrally with the input shaft (6), an output body (8) arranged along the outer circumferential surface of the input shaft (6) and rotating about an axis (60) by receiving the rotational force of the input body (7), and a control board (35) housed in the unit case (4) and controlling the rotation of the motor (5). The unit case (4) has a first heat dissipation section (414) connected to the first surface (351) of the control board (35) and a second heat dissipation section (424) connected to the second surface (352) opposite to the first surface (351) of the control board (35).

[0117] In the motor unit (3) for electric bicycles according to the tenth embodiment, the heat from the control board (35) is efficiently dissipated from both sides via the first heat dissipation section (414) and the second heat dissipation section (424). Therefore, the heat dissipation performance of the motor unit (3) for electric bicycles can be improved.

[0118] The motor unit (3) for electric bicycles according to the eleventh embodiment is realized by combining it with the tenth embodiment. The motor unit (3) for electric bicycles according to the eleventh embodiment further comprises a heat conductive member (9) disposed within the unit case (4). The heat conductive member (9) is disposed between the first heat dissipation section (414) and the control board (35), and between the second heat dissipation section (424) and the control board (35), at least one of the two.

[0119] In the motor unit (3) for electric bicycles according to the eleventh embodiment, heat from the control board (35) is dissipated more efficiently through the thermally conductive member (9).

[0120] The motor unit for electric bicycles (3) of the twelfth embodiment is realized by combining it with the eleventh embodiment. In the motor unit for electric bicycles (3) of the twelfth embodiment, the control board (35) includes electrical components (353). The thermal conductive member (9) is in contact with the electrical components (353).

[0121] In the motor unit (3) for electric bicycles according to the twelfth embodiment, heat from the electrical components (353) is efficiently dissipated through the heat-conducting member (9).

[0122] The motor unit for electric bicycles (3) of the 13th embodiment is realized by combining it with any one of the 10th to 12th embodiments. In the motor unit for electric bicycles (3) of the 13th embodiment, the control board (35) includes a heating element (3531). At least one of the first heat dissipation section (414) and the second heat dissipation section (424) is positioned to overlap with the heating element (3531) when viewed in the thickness direction of the control board (35).

[0123] In the motor unit for electric bicycles (3) of the 13th embodiment, the heat generated by the heat-generating element (3531) in the control board (35), which tends to get particularly hot, is dissipated more efficiently.

[0124] The motor unit for electric bicycles (3) of the 14th embodiment is realized by combining it with any one of the 10th to 13th embodiments. In the motor unit for electric bicycles (3) of the 14th embodiment, the first heat dissipation section (414) is located in a position that overlaps with the second heat dissipation section (424) when viewed in the thickness direction of the control board (35).

[0125] In the motor unit (3) for electric bicycles according to the 14th embodiment, the control board (35) is sandwiched from both sides by the first heat dissipation section (414) and the second heat dissipation section (424), which improves heat dissipation, as well as the reliability of fixing the control board (35), and consequently improves the vibration resistance of the motor unit (3).

[0126] The electric bicycle (1) of the 15th embodiment comprises an electric bicycle motor unit (3) of any one of the 10th to 14th embodiments and a wheel (11) to which the rotational force of the motor (5) of the electric bicycle motor unit (3) is transmitted.

[0127] In the electric bicycle (1) of the 15th embodiment, improved heat dissipation of the electric bicycle motor unit (3) can be achieved in the electric bicycle (1). [Explanation of Symbols]

[0128] 1. Electric bicycle 11 wheels 3 Motor Unit 31 Reduction mechanism 35 Control board 353 Electrical components 3531 Heating element 4 Unit Case 414 1st heat dissipation section 424 2nd heat dissipation section 49 O-rings 5 Motors 51 Rotation axis 52 rotors 53 Status 530 Outer surface 535 Metal surface 552 Bearing 57 Metal cup 570 Inner surface 574 Opening edge 578 recess 6 Input axes 60 axis 7 Input fields 8 Output Units 9. Thermally conductive members

Claims

1. A motor having a stator, rotor, and rotating shaft, A unit case in which a part of the aforementioned rotating shaft is housed, A control board housed in the aforementioned unit case controls the rotation of the motor, The system includes a thermally conductive member that, by contacting the control board and the unit case, conducts heat from the control board to the unit case, When viewed in the axial direction of the rotation axis, the control board and the stator are arranged so that at least a portion of them overlap. The heat-conducting member is in contact with the surface of the control board facing the stator and the unit case. Motor unit for electric bicycles.

2. The unit case comprises a first divided body and a second divided body, The first divided body is in contact with the heat-conducting member, The portion of the first divided body that is in contact with the heat-conducting member is formed to be thicker than the surrounding portion and is formed to protrude inward into the unit case. Motor unit for electric bicycle according to claim 1.

3. A motor having a stator, a rotor, and a rotating shaft, A unit case in which a part of the aforementioned rotating shaft is housed, A control board, housed in the unit case, having a first surface and a second surface opposite to the first surface, controls the rotation of the motor, The system includes a thermally conductive member that, by contacting the control board and the unit case, conducts heat from the control board to the unit case, When viewed in the axial direction of the rotation shaft of the motor, the control board and the stator are arranged so that at least a portion of them overlap, and the first surface of the control board faces the stator. The thermal conductive member comprises a first thermal conductive member that contacts the first surface of the control board and the unit case, and a second thermal conductive member that contacts the second surface of the control board and the unit case. Motor unit for electric bicycles.

4. The unit case comprises a first divided body and a second divided body, The first thermal conductive member is in contact with the first divided body, The second thermal conductive member is in contact with the second divided body. The motor unit for an electric bicycle according to claim 3.

5. The unit case further comprises a reduction mechanism that is housed therein and reduces and transmits the rotation of the motor, The first divided body supports the reduction mechanism. The motor unit for an electric bicycle according to claim 4.

6. The second heat-conducting member is provided in a position that overlaps with the motor when viewed in the axial direction of the rotation shaft of the motor, A motor unit for an electric bicycle according to any one of claims 3 to 5.

7. A motor equipped with a rotating shaft, A unit case in which a part of the aforementioned rotating shaft is housed, An input shaft is positioned within the unit case so as to penetrate the unit case and is rotatable around its axis, An input body is arranged along the outer circumferential surface of the input shaft and rotates integrally with the input shaft, An output body is arranged along the outer circumferential surface of the input shaft and rotates around the axis in response to the rotational force of the input body, A one-way clutch is disposed between the input and output units, The unit case is housed in the aforementioned unit case and comprises a control board for controlling the rotation of the motor, The aforementioned unit case is A first heat dissipation unit connected to the first surface of the control board, The control board has a second heat dissipation section connected to a second surface opposite to the first surface, The input body comprises a first input body connected to the input shaft and a second input body that transmits rotational force to the output body. The second input body is positioned radially inward of the one-way clutch, The output unit is positioned radially outward of the one-way clutch. Motor unit for electric bicycles.

8. The unit case further comprises a heat-conducting member, The heat-conducting member is disposed between the first heat dissipation unit and the control board, and between the second heat dissipation unit and the control board, The motor unit for an electric bicycle according to claim 7.

9. The control board includes a heating element, At least one of the first heat dissipation section and the second heat dissipation section is located in a position that overlaps with the heat generating element when viewed in the thickness direction of the control substrate. The motor unit for an electric bicycle according to claim 7.

10. The first heat dissipation section is located in a position that overlaps with the second heat dissipation section when viewed in the thickness direction of the control board. The motor unit for an electric bicycle according to claim 7.

11. The control board includes a heating element, At least one of the first heat dissipation section and the second heat dissipation section is located in a position that overlaps with the heat generating element when viewed in the thickness direction of the control substrate. The thermal conductive member has a second thermal conductive member disposed between the second heat dissipation section and the control substrate. The second heat-conducting member is in contact with the plurality of heat-generating elements. The motor unit for an electric bicycle according to claim 8.

12. The thermal conductive member has a first thermal conductive member disposed between the first heat dissipation unit and the control substrate, The first thermal conductive member is in contact with the plurality of heating elements. The motor unit for an electric bicycle according to claim 11.

13. The first divided part of the unit case integrally includes the first heat dissipation section, A portion of the first divided body is formed to be thicker than the surrounding portion. The first heat dissipation section is configured such that the thick portion protrudes inward from the unit case. The motor unit for an electric bicycle according to claim 7.

14. The second divided part of the unit case integrally includes the second heat dissipation section, A portion of the second divided body is formed to be recessed inward compared to the surrounding portion. The second heat dissipation section is configured such that the bottom of the recessed portion protrudes inward from the unit case. The motor unit for an electric bicycle according to claim 7.

15. The edge portion of the control board that is away from the input shaft is sandwiched between the first heat dissipation portion and the second heat dissipation portion. The motor unit for an electric bicycle according to claim 7.

16. The output body is a cylindrical member, rotatably arranged along the outer circumferential surface of the input shaft, One end of the output unit protrudes outside the unit case through the through hole of the second divided body. The motor unit for an electric bicycle according to claim 14.

17. The first heat dissipation unit or the second heat dissipation unit is provided in the vicinity of the motor. The motor unit for an electric bicycle according to claim 7.

18. The first heat dissipation section or the second heat dissipation section is provided in a position that overlaps with the motor when viewed in the axial direction of the motor's rotation shaft. The motor unit for an electric bicycle according to claim 7.

19. The first heat dissipation section and the second heat dissipation section are formed on the inner surface of the unit case. The motor unit for an electric bicycle according to claim 7.

20. The control board is placed on the first heat dissipation unit or the second heat dissipation unit. The motor unit for an electric bicycle according to claim 7.

21. The system further includes a reduction mechanism for transmitting the rotational force of the motor, The first heat dissipation section or the second heat dissipation section is located further from the input shaft than the reduction mechanism. The motor unit for an electric bicycle according to claim 7.

22. The motor unit for electric bicycles according to claim 7, The electric bicycle motor unit comprises a wheel to which the rotational force of the motor is transmitted. Electric bicycle.

23. A motor having a rotating shaft, A unit case in which a part of the aforementioned rotating shaft is housed, The aforementioned unit case has an input shaft that is rotatable around its axis, An input body is arranged along the outer circumferential surface of the input shaft and rotates integrally with the input shaft, An output body is arranged along the outer circumferential surface of the input shaft and rotates around its axis in response to the rotational force of the input body, A one-way clutch is disposed between the input and output units, A motor unit for an electric bicycle, comprising: a control board housed in the unit case, having a first surface and a second surface opposite to the first surface, and controlling the rotation of the motor, A first thermal conductive member in contact with the first surface, A first heat dissipation section that contacts the first heat conductive member and conducts heat from the control board to the outer shell of the electric bicycle motor unit, A second thermal conductive member in contact with the second surface, The device comprises a second heat dissipation section that contacts the second heat conductive member and conducts heat from the control board to the outer shell of the electric bicycle motor unit, The input body comprises a first input body connected to the input shaft and a second input body that transmits rotational force to the output body. The second input body is positioned radially inward of the one-way clutch, The output unit is positioned radially outward of the one-way clutch. Motor unit for electric bicycles.

24. A motor having a rotating shaft, A unit case that houses a part of the aforementioned rotating shaft and has a first divided body and a second divided body, The aforementioned unit case has an input shaft that is rotatable around its axis, An input body is arranged along the outer circumferential surface of the input shaft and rotates integrally with the input shaft, An output body is arranged along the outer circumferential surface of the input shaft and rotates around the axis in response to the rotational force of the input body, A one-way clutch is disposed between the input and output units, A reduction mechanism housed in the aforementioned unit case, which reduces and transmits the rotational force of the motor, A sprocket that outputs the resultant force of the human power transmitted to the input body and the rotational force of the motor transmitted by the reduction mechanism, A control board housed in the aforementioned unit case controls the rotation of the motor, The unit case comprises a heat-conducting member disposed within the unit case, The second divided body is formed to be recessed inward from the surrounding portion of the unit case, and the bottom of the recessed portion has a heat dissipation section connected to the control board. The heat dissipation section is connected to the control board via the thermal conductive member, The input body comprises a first input body connected to the input shaft and a second input body that transmits rotational force to the output body. The second input body is positioned radially inward of the one-way clutch, The output unit is positioned radially outward of the one-way clutch. Motor unit for electric bicycles.

25. The contact surface between the thermal conductive member and the control substrate is located on the side of the first divided body than the joint surface between the first divided body and the second divided body. The motor unit for an electric bicycle according to claim 24.

26. The control board includes electrical components, The heat-conducting member is in contact with the electrical component. Motor unit for electric bicycle according to claim 24 or 8.

27. The heat dissipation section is provided in a position that overlaps with the motor when viewed in the axial direction of the motor's rotating shaft. The motor unit for an electric bicycle according to claim 24.

28. The control board has a capacitor, The capacitor is positioned so as to overlap with the motor when viewed in the axial direction of the motor's rotating shaft. Motor unit for electric bicycle according to claim 24 or 7.

29. The heat dissipation section is located further away from the input shaft than the reduction mechanism. The motor unit for an electric bicycle according to claim 24.

30. The unit case is further equipped with a torque detector that is housed therein and detects the torque applied to the input shaft, The control board is positioned so as to overlap with the torque detector when viewed from a direction perpendicular to the axial direction of the motor's rotation shaft. The motor unit for an electric bicycle according to claim 24.

Images