Motor unit for use in electric bicycles and e-bikes

Abstract

Motor unit (3) for use in an electric bicycle, the motor unit comprising: a motor (5) having a rotating shaft (51); a unit housing (4) that at least partially houses the motor (5), the unit housing (4) having a first subdivision part (41) and a second subdivision part (42); an input shaft (6) arranged in the unit housing (4), passing through the unit housing (4) and rotatable about an axis (60); an input body (7) arranged about an outer circumferential surface of the input shaft (6) and configured to rotate together with the input shaft (6); an output body (8) arranged along the outer circumferential surface of the input shaft (6) and configured to rotate about the axis (60) when receiving a rotational force from the input body (7); a freewheel clutch (32) arranged such that it is located between the input body (7) and the output body (8). is;a control or regulating board (35) housed in the unit housing (4) and designed to control or regulate the rotation of the motor (5); a first bearing (552) arranged to rotatably support the rotating shaft (51); a bearing retaining element (578) arranged to hold the first bearing (552); and a second thermally conductive element (92) arranged in the unit housing (4), wherein the second subdivision part (42) has a second heat dissipation section (424) which is connected to the control board (35) via the second thermally conductive element (92), a section of the second subdivision part (42) forms the second heat dissipation section (424) which curves inwards in the unit housing (42), the bearing retaining element (578) is attached to the first subdivision part (41), the input body (7) includes: a first input body (71) which is coupled to the input shaft (6);and a second input body (72) which is coupled to the first input body (71) and is designed to transmit a rotational force to the output body (8), wherein the second input body (72) is arranged radially inwards from the freewheel clutch (32), and wherein the output body (8) is arranged radially outwards from the freewheel clutch (32).

Description

Technical field The present disclosure relates generally to a motor unit for use in electric bicycles and also relates to an electric bicycle. background Patent document 1 discloses an electric bicycle (i.e., an electrically assisted bicycle) comprising a motor unit. The motor unit houses a motor within a single housing that forms its enclosure. This housing includes a motor casing for the motor. The motor casing, together with a stator of the motor, is formed from resin using a molding technique. The motor unit known from the aforementioned patent document 1 still has room for improvement with regard to its ability to dissipate the heat generated when the motor is activated. List of citations Patent literature Patent Publication 1: WO 2014 / 184826 A1 Summary of the invention The purpose of the present disclosure is therefore to provide a motor unit intended for electric bicycles with improved heat dissipation capability and also to provide an electric bicycle that includes such a motor unit. A motor unit according to one aspect of the present disclosure is designed for use in electric bicycles. The motor unit comprises a motor and a unit housing into which the motor is fitted. The motor includes: a stator; a rotor arranged to be surrounded by the stator; a rotating shaft attached to the rotor; and a metallic shell having an opening and designed to at least partially accommodate the stator and the rotor. An inner circumferential surface of the metallic shell is in pressure contact with the stator. An electric bicycle according to another aspect of the present disclosure includes the motor unit according to one aspect; and at least one wheel to which a rotational force is transmitted from the motor of the motor unit. Brief description of the drawing Fig. 1 is a side view of an electric bicycle according to an exemplary embodiment. Fig. 2A is a side view of a motor unit intended for the electric bicycle. Fig. 2B is a perspective view of the motor unit. Fig. 3 is a cross-sectional view of the motor unit along plane AA in Fig. 2A. Fig. 4 is a perspective exploded view of essential parts of the motor unit. Fig. 5 is another perspective exploded view of some of the essential parts of the motor unit. Fig. 6 is a side view of a metallic housing of the motor unit. Fig. 7 is a cross-sectional view showing a first modification of the motor unit. Fig. 8 is a cross-sectional view showing a second modification of the motor unit. Fig. 9 is a cross-sectional view showing a third modification of the motor unit. Description of embodiments Exemplary embodiment An electric bicycle 1 according to an exemplary embodiment is implemented as an electrically assisted bicycle. The electric bicycle 1 according to the exemplary embodiment includes: a frame 10; a motor unit 3 intended for use in electric bicycles (hereinafter simply referred to as the "motor unit 3"), which is mounted on the frame 10; and two wheels 11, which are rotatably coupled to the frame 10. The two wheels 11 are a front wheel 111 and a rear wheel 112. The rear wheel 112 is driven to rotate by a driving force supplied by the motor unit 3. Note that in the following description, the respective directions, including forward / backward and right / left, are defined in relation to the rider of the electric bicycle 1. Specifically, the direction in which the rider of the electric bicycle 1 moves by pedaling is the forward direction, while the opposite direction is the backward direction. The direction to the left when viewed from the rider's perspective is the left direction, while the direction to the right when viewed from the rider's perspective is the right direction. The respective constituent elements of these directions are now described in detail. First, frame 10 is described. As shown in Fig. 1, the frame 10 includes a head tube 101, an upper tube 102, a lower tube 103, a seat tube 104, seat stays 105, chain stays 106 and a bracket 2. The frame 10 (that is, the individual parts that form the frame 10) is usually made of a metal such as aluminum or stainless steel, which may also contain a non-metallic material. Alternatively, the entire frame 10 can also be made of a non-metallic material. Therefore, the frame 10 can be made of any material without restriction. A steering stem 12 is rotatably inserted into the head tube 101. A fork 121 is provided at the lower end of the steering stem 12, to which the front wheel 111 is rotatably mounted. A steering rod 122 is attached to the upper end of the steering stem 12. A front end section of the upper tube 102 is attached to the head tube 101. A rear end section of the upper tube 102 is attached to the seat tube 104. A tube 132, extending downwards from a saddle 13, is inserted into a hole at the top of the seat tube 104. The attachment of the tube 132 to the seat tube 104 ensures that the saddle 13 is secure. The bracket 2 is attached to the bottom of the seat tube 104. A front end section of the lower tube 103 is also attached to the head tube 101. A rear end section of the lower tube 103 is attached to the bracket 2. The motor unit 3 is attached below the bracket 2. The respective front end sections of the chainstays 106 are attached to a rear end section of the bracket 2. At a rear end section of the upper tube 102, the respective front end sections of the seat stays 105 are attached. The respective rear end sections of the seat stays 105 are coupled to the respective rear end sections of the chainstays 106. The rear wheel 112 is rotatably mounted to their coupling sections. A battery 15 for supplying power to the motor unit 3 is detachably mounted to the lower tube 103. Next, motor unit 3 will be described. As shown in Figs. 2A and 2B, the majority of the housing for the motor unit 3 is formed by a unit housing 4. As shown in Fig. 3, a motor 5, which serves as the drive source for rotating the wheels 11, is fitted into the unit housing 4. The unit housing 4 contains a speed reducer 31, to which the torque of the motor 5 is transmitted, and a control board 35 for controlling the rotation of the motor 5. The unit housing 4 also contains an input shaft 6, an input body 7, an output body 8, and other components. A metallic shell 57, shaped like a cylinder with a base for housing essential parts of the engine 5, is fitted to the outer surface of the unit housing 4. The metallic shell 57 has an opening, the opening edge section 574 of which is coupled to the unit housing 4. Parts of the motor 5 not housed in the metallic shell 57 (such as a section of a rotating shaft 51, which will be described below) are housed in the unit housing 4. Several first mounting pieces 401 and several second mounting pieces 402, all of which are to be attached to the bracket 2, project from the outer surface of the unit housing 4. The unit housing 4 comprises a first subdivision part 41, which forms a left half of the unit housing 4, and a second subdivision part 42, which forms a right half of the unit housing 4. Several first mounting pieces 401 project from the first subdivision part 41, and several second mounting pieces 402 project from the second subdivision part 42. A hollow unit housing 4 is formed by joining the first subdivision part 41 and the second subdivision part 42. As shown in Figures 3 and 4 and in other figures, the first subdivision part 41 has a space that is open to the right. This space forms the left half of the housing space of the unit housing 4. The first subdivision part 41 has a wall 415 in a region oriented towards the motor 5. The wall 415 has a circular through-hole 412 and an arcuate through-hole 413 that is concentric with the through-hole 412. A part of the motor 5 (in particular the drive shaft 51, which will be described below) is inserted into the through-hole 412. A power supply cable for the motor 5 and a resin section forming the cable are passed through the through-hole 413. The second subdivision 42 has a space that is open to the left. This space forms the right half of the accommodation space of the unit housing 4. The first subdivision 41 and the second subdivision 42 are joined in such a way that their respective spaces communicate with each other. The metallic shell 57, which is provided for the motor 5, comprises: a circular bottom wall 572; a circumferential wall 573 extending from the circumferential edge of the bottom wall 572; and an opening edge section 574 formed in the form of a flange at the apex of the circumferential wall 573 (see Fig. 5 and Fig. 6). The circumferential wall 573 extends along the thickness of the bottom wall 572. The metallic shell 57 is usually made of aluminum. However, this is only one example and should not be interpreted as a limitation. Alternatively, the metallic shell 57 can also be made of iron, a magnesium alloy, titanium, or another suitable material. The opening edge section 574, which has the shape of a ring, has: several screw holes 575, which are arranged at intervals in the circumferential direction; several projections 576, which are also arranged at intervals in the circumferential direction; and an annular groove 577 (see Fig. 6). The multiple screw holes 575 are provided to accommodate multiple screws 571, each of which is to be screwed in. The multiple projections 576 are provided to position the metallic shell 57 by fitting into recesses on the outer surface of the first subdivision part 41. The groove 577 is provided to accommodate an O-ring 49. The groove 577 extends over the entire circumference of the opening edge section 574. The groove 577 is located radially inward from (that is, closer to the center of the opening of the metallic shell 57 compared to) the multiple screw holes 575 and the multiple projections 576. The profile of the groove 577 is not a perfect circle, but is curved radially inward in the areas where the screw holes 575 and the projections 576 are provided (see Fig. 6). This allows the outer dimension of the opening edge section 574 of the metallic shell 57 to decrease in the motor unit 3 according to the present embodiment. However, this is only one example of the present disclosure and should not be interpreted as limiting. Alternatively, the groove 577 can also be configured to have the profile of a perfect circle. To fasten the metallic shell 57 to the outer surface of the first subdivision part 41, several screws 571 can be inserted through the opening of the first subdivision part 41 (see Fig. 4) and screwed into their corresponding screw holes 575 through the first subdivision part 41. This allows the opening edge section 574 of the metallic shell 57 to be hermetically and elastically fastened to the outer surface of the first subdivision part 41 by means of the O-ring 49. The arrangement of the O-ring 49 between the metallic shell 57 and the unit housing 4 offers the advantage of reduced vibration transmission. As shown in Fig. 3, the motor 5 includes: a circular column-shaped rotating shaft 51; a rotor 52 coupled to and rotating with the rotating shaft 51; and a circular cylindrical stator 53 arranged to surround the rotor 52. The metallic shell 57 encloses an axial portion of the rotating shaft 51 (in particular, an axial half of the rotating shaft 51), the rotor 52, and a portion of the stator 53 (in particular, a large part of the stator 53). The remainder of the rotating shaft 51 (in particular, the other axial half of the rotating shaft 51) and the remainder of the stator 53 (in particular, a resin-molded portion of the stator 53) protrude through the opening of the metallic shell 57. A recess 578 for receiving a bearing 552 is provided on the inner surface of the bottom wall 572 of the metallic shell 57. The bearing 552 is designed to rotatably support an axial end section of the rotating shaft 51. The other axial end section of the rotating shaft 51 is rotatably supported by another bearing 551, which is located in a further recess 428 provided on the inner surface of the second subdivision part 42. Teeth 54 are formed on the outer circumferential surface of a section of the rotating shaft 51 projecting from the metallic shell 57, which mesh with the speed reducer 31. In the motor unit 3 according to the exemplary embodiment, an inner circumferential surface 570 of the metallic shell 57 (that is, the inner circumferential surface of the metallic circumferential wall 573) is in sufficiently close pressure contact with the outer circumferential surface 530 of the stator 53 over its entire circumference. For the purposes of this document, the statement "that the inner circumferential surface 570 of the metallic shell 57 is brought into pressure contact with the stator 53" means that the inner circumferential surface 570 of the metallic shell 57 is brought into contact with the stator 53 by pressure. Pressure is exerted between the inner circumferential surface 570 of the metallic shell 57 and the outer circumferential surface 530 of the stator 53, causing the inner circumferential surface 570 and the outer circumferential surface 530 to be pressed against each other. The metallic shell 57 is thermally inserted into the stator 53. Specifically, the metallic shell 57 is fitted onto the stator 53 after being heated and expanded. As the metallic shell 57 shrinks when its temperature subsequently decreases, it is brought into close pressure contact with the stator 53. The inner circumferential surface 570 of the metallic shell 57 is an annular, continuous metallic surface. The inner circumferential surface 570 of the metallic shell 57 is in close contact with the outer circumferential surface 530 of the stator 53 over its entire circumference by means of pressure. A portion of the outer circumferential surface 530 of the stator 53 that is not formed from resin is the metallic surface 535. The stator 53 is not entirely, but only partially, formed from resin such that at least the metallic surface 535 on its outer circumference is exposed. The metallic surface 535 is the outer circumferential surface of an iron core 533 of the stator 53. A coil 534, which is wound around the iron core 533, is formed from resin. As can be seen, in the exemplary embodiment of motor unit 3, the stator 53, with the exception of a part thereof, is formed entirely from resin. This part includes a section of the stator 53 which is designed to be in pressure contact with the inner circumferential surface 570 of the metallic shell 57 (i.e., the outer circumferential surface 530 of the stator 53). Therefore, the heat generated inside the motor 5 is transferred directly from the stator 53 to the metallic shell 57 and efficiently dissipated through the metallic shell 57 into the open air. The surface of the metallic shell 57 can be exposed to the air blowing against the moving electric bicycle. As will be described below with reference to variations, the stator 53 need not be made of resin. As shown in Fig. 5, a counter-rotating pin 48 is provided between the metallic shell 57 and the stator 53. A straight groove 538, into which part of the pin 48 is fitted, is formed on the outer circumferential surface 530 of the stator 53. A straight groove 579, into which another part of the pin 48 is fitted, is formed on the inner circumferential surface 570 of the metallic shell 57 (see Fig. 6). The pin 48 is arranged parallel to the axis of the motor 5 (i.e., to the axis of the rotating shaft 51). The insertion of the pin 48 between the metallic shell 57 and the stator 53 allows for more reliable monitoring of the relative rotation of the metallic shell 57 with respect to the stator 53. In addition, in the exemplary embodiment of the motor unit 3, the stator 53 includes a section 531 that protrudes through the opening of the metallic shell 57 (see Fig. 4). This section 531 serves as a guide when the O-ring 49 is fitted or is fitted. The preceding description refers to the structure of the motor 5. Next, various types of mechanisms housed in the unit casing 4 are described. As shown in Fig. 3, the input shaft 6 is rotatably mounted about the axis 60 of the unit housing 4. The first subdivision part 41 has a through-hole 411 into which the input shaft 6 is inserted. The second subdivision part 42 also has a through-hole 421 into which the input shaft 6 is inserted. Crank arms 18 are attached to both ends of the input shaft 6. A pedal 181 is rotatably mounted at the tip of each crank arm 18 (see Fig. 1). The rider can exert a physical rotational force on the input shaft 6 by pedaling the pedals 181. In the unit housing 4, the input body 7 is arranged along the outer circumferential surface of the input shaft 6. The input body 7 is a cylindrical element and rotates together with the input shaft 6. The input body 7 is divided into a first input body 71 and a second input body 72. The first input body 71 is coupled to the input shaft 6 in the first subdivision 41. The second input body 72 is coupled to the first input body 71 in the second subdivision 42. The second input body 72 transmits a rotational force to the output body 8. The output body 8 is a cylindrical body and is rotatably arranged along the outer circumferential surface of the input shaft 6. An end section of the output body 8 extends through the through-hole 421 of the second subdivision part 42 and projects from the unit housing 4. A front sprocket 191 is attached to the section of the output body 8 projecting from the unit housing 4. The front sprocket 191 rotates together with the output body 8. A rear sprocket 192 is attached to a hub of the rear wheel 112 (see Fig. 1). A chain 193 runs between the front sprocket 191 and the rear sprocket 192. As shown in Fig. 3, a freewheel clutch 32 is arranged in the unit housing 4 such that it is located between the input body 7 and the output body 8. The freewheel clutch 32 is designed to transmit a torque to the output body 8 when a torque is applied to the input body 7 in an acceleration direction, and is also designed to interrupt the transmission of the torque to the output body 8 when a torque is applied to the input body 7 in a deceleration direction. For the purposes of this document, the "acceleration direction" refers to the direction in which the electric bicycle 1 is accelerated in its direction of movement, while the "deceleration direction" is opposite to the acceleration direction. The output body 8 includes a web 81 and a rim 82 as its integral elements. The web 81 projects radially outwards with respect to the output body 8. The rim 82 is continuous with a radially outer end section of the web 81. Teeth 83 are formed on the outer circumferential surface of the rim 82, which mesh with the velocity reducer 31. The speed reducer 31, which is housed in the unit casing 4, is designed to reduce the speed of the motor 5 and to transmit a reduced torque to the output body 8. The speed reducer 31 includes a rotating shaft 310 as well as a first gear wheel 311 and a second gear wheel 312, both of which are supported by the rotating shaft 310. The first gear wheel 311 is a cylindrical element that receives the rotational force from the rotating shaft 51 of the motor 5. Teeth 313 are formed on the outer circumferential surface of the first gear wheel 311, which mesh with the teeth 54 of the rotating shaft 51. The rotary shaft 310 is rotatably housed in the unit housing 4 such that its axis is aligned with the right / left direction. An end section of the rotary shaft 310 is rotatably supported by a bearing 314, which is arranged in the second subdivision part 42. The first gear wheel 311 is coupled to the rotating shaft 310 via a freewheel clutch 315. The freewheel clutch 315 is designed to transmit the torque to the rotating shaft 310 when a torque is transmitted to the first gear wheel 311 in an acceleration direction, and is also designed to interrupt the transmission of the torque to the rotating shaft 310 when a torque is transmitted to the first gear wheel 311 in a deceleration direction. The second gear wheel 312 is attached to the rotating shaft 310 in such a way that it rotates together with the rotating shaft 310. The second gear wheel 312 transmits the rotational force from the transmission of the first gear wheel 311 via the rotating shaft 310 to the teeth 83 of the output body 8. Teeth 316 are formed on the outer circumferential surface of the second gear wheel 312, which mesh with the teeth 83. The motor unit 3, according to the exemplary embodiment, has such a design. Therefore, when the input shaft 6 rotates in the direction of acceleration as the rider pedals the electric bicycle 1, the first input body 71 and the second input body 72 rotate together with the input shaft 6. If the rotational force in the direction of acceleration of the second input body 72 is transmitted to the output body 8 via the freewheel clutch 32, the output body 8 and the front sprocket 191 rotate in the direction of acceleration. When the front sprocket 191 rotates in the direction of acceleration, its rotational force is transmitted via the chain 193 to the rear sprocket 192, which causes the rear sprocket 192 to rotate in the direction of acceleration and thereby drives the rear wheel 112 to rotate in the direction of acceleration. In addition, according to the exemplary embodiment, the motor unit 3 can transmit the torque output by the motor 5 to the output body 8, which is described below. When the rotating shaft 51 of the motor 5 rotates in the direction of acceleration, the first gear wheel 311, which is engaged with the rotating shaft 51, also rotates in the direction of acceleration. The torque in the direction of acceleration of the first gear wheel 311 is transmitted to the rotating shaft 310 and the second gear wheel 312 via the freewheel clutch 315, causing the second gear wheel 312 to rotate in the direction of acceleration. The torque in the direction of acceleration of the second gear wheel 312 is transmitted to the output body 8. The torque generated by the motor 5 and the torque generated by the rider pressing the pedals 181 are transmitted to the output body 8 in combination. In the electric bicycle 1 according to the exemplary embodiment, a control unit, which is included in the control board 35, controls the rotation of the motor 5 according to a torque exerted on the input shaft 6 and the rotational speed per unit time of the input shaft 6. The torque exerted on the input shaft 6 is detected by a torque detector 33, which is housed in the unit housing 4. The torque detector 33 is a magnetostrictive torque detector which includes a magnetostriction generation unit 331, which is formed on the outer circumferential surface of the first input body 71, and a coil 332, which is arranged at a very short distance from the magnetostriction generation unit 331. The rotational speed per unit time of the input shaft 6 is detected by a rotary detector 34. The rotary detector 34 is an optical rotary detector comprising a rotator 341, which rotates together with the input body 7, and an optical sensor 342, which is arranged at a very short distance from the rotator 341. The control unit of the control board 35 can, for example, contain a microcomputer and controls the operation of the respective constituent elements by executing a program stored on a storage medium, such as a read-only memory (ROM). A known control unit can be used as the control unit as required. In the motor unit 3 according to the exemplary embodiment with such a design, the heat in the stator 53 is transferred directly to the metallic shell 57 via the metallic surface 535 and then efficiently dissipated from the outer surface of the metallic shell 57. Since the amount of resin used as a material is also reduced, the motor unit 3 can have a lower overall weight. Variations Next, some modifications of the motor unit 3 and the electric bicycle 1 according to the exemplary embodiment are described. In the subsequent description of modifications, any constituent element that has the same function as a counterpart in the previously described exemplary embodiment is designated with the same reference numeral as the counterpart, and a detailed description of it is omitted. Fig. 7 shows a cross-section through a first modification of the motor unit 3. In the motor unit 3 shown in Fig. 3 and in other figures, the stator 53 is partially formed from resin. According to the first modification of the motor unit 3, however, the stator 53 is not formed from resin. This means that neither the iron core 533 of the stator 53 nor the coil 534 wound around the iron core 533 is made of resin. The metallic surfaces 535, formed by the outer circumferential surface of the iron core 533 and the inner circumferential surface 570 of the metallic shell 57, are in close contact with each other due to pressure, causing the surfaces 535 and 570 to be pressed against each other. In the first modification of the motor unit 3, the stator 53 is not made of resin, which allows the motor 5 to have an even lower overall weight. However, if the stator 53 is made entirely of resin, with the exception of the metallic surface 535 (i.e., in the embodiment shown in Fig. 3 and other figures), advantages are achieved in that a significant increase in the temperature of the stator 53 due to the heat storage properties of the resin section is reduced, the resin section also reduces noise and vibrations, and increases the degree of insulation between the coil 534 and the metallic shell 57. Fig. 8 shows a cross-section through a second modification of the motor unit 3. The motor unit 3 shown in Fig. 3 and in other figures is a so-called "uniaxial or single-axis motor unit". In contrast, the second modification of the motor unit 3 is a biaxial or two-axis motor unit 3. In the second modification of the motor unit 3, the motor unit 3 includes a second output body 310B, which is different from the output body 8. A first end section of the second output body 310B is located in the unit housing 4. The second output body 310B is rotatably supported by a bearing 3191B, which is arranged in the first subdivision part 41, and a bearing 3192B, which is arranged in the second subdivision part 42. A second end section of the second output body 310B projects from the unit housing 4. A sprocket 194B is attached to the second end section of the second output body 310B. A chain 193 is guided around the sprocket 194B. A large-diameter wheel or gear 318B is mounted on the outer circumferential surface of the second output body 310B via a freewheel clutch 317B. The wheel or gear 318B meshes with the teeth 54 on the rotating shaft 51 of the motor 5. In the electric bicycle 1, which includes the second modification of the motor unit 3, when the rotating shaft 51 of the motor 5 rotates in the acceleration direction while the rider is riding by pedaling 181, the wheel or gear 318B rotates in the acceleration direction, and the rotational force is transmitted via the freewheel clutch 317B to the second output body 310B and then to the chain 193. Next, a third modification of the motor unit 3 will be described with reference to Fig. 9. In the third modification of the motor unit 3, the first subdivision part 41 of the unit housing 4, which is made of a metallic material, includes as an integral part a first heat dissipation section 414. One section of the first subdivision part 41 is thicker than a surrounding section. This thicker section of the first subdivision part 41 forms the first heat dissipation section 414, which is made of a metallic material and curves inwards within the unit housing 4. The first heat dissipation section 414 is connected to a first surface 351 along the thickness of the control board 35 via a first thermally conductive layer 91, which serves as a thermally conductive element 9. For the purposes of this document, when something is "connected" to something else, these two things can be in direct contact with each other naturally, without any other element being arranged between them; however, they can also be connected indirectly, with another element being arranged between them. The thickness of the control board 35 is the thickness of a printed circuit board 354 contained within the control board 35 and corresponds to the right / left direction in the third modification of the motor unit 3. The first surface 351 of the control board 35 is a surface along the thickness of the printed circuit board 354 and forms a substantial part of it. A second surface 352 of the control board 35 is another surface along the thickness of the printed circuit board 354 and forms a substantial part of it. The control board 35 further includes several electrical components 353, which are mounted together on the printed circuit board 354. These electrical components 353 include, for example, not only capacitors 3532 and integrated circuits 3533, but also heat-generating elements 3531, which tend to generate heat particularly easily. Examples of heat-generating elements 3531 include not only switching elements, such as a field-effect transistor (FET), a diode, and an inductor, which are used to supply power to the motor 5, but also, for example, various types of resistors and connections. The second subdivision 42 of the unit housing 4 includes a second heat dissipation section 424 as an integral part thereof. In the third modification of the motor unit 3, a section of the second subdivision 42 is designed such that it is recessed inwards relative to a surrounding section thereof. The base of the recessed section of the second subdivision 42 forms the second heat dissipation section 424, which is made of a metallic material and curves inwards within the unit housing 4. The second heat dissipation section 424 is connected to the second surface 352 of the control board 35 via a second thermally conductive layer 92, which serves as a thermally conductive element 9. The second surface 352 is oriented in the opposite direction to the first surface 351. Several heat-generating elements 3531 are in contact with the second thermally conductive layer 92. The heat generated by the several heat-generating elements 3531 is efficiently dissipated from the outer surface of the unit housing 4 via the second thermally conductive layer 92 and the second heat dissipation section 424. Note that the number of heat-generating elements 3531 in contact with the second thermally conductive layer 92 need not be greater than 1, but can also be equal to 1. Furthermore, the one or more heat-generating elements 3531 can be in contact with the first thermally conductive layer 91. The one or more heat-generating elements 3531 can be in contact with each of the first thermally conductive layer 91 and the second thermally conductive layer 92. As can be seen, in the third modification of the motor unit 3, the first heat dissipation section 414, which forms an integral part of the unit housing 4, is connected to the first surface 351 of the control board 35, and the second heat dissipation section 424, which also forms an integral part of the unit housing 4, is connected to the second surface 352 of the control board 35. Since the heat generated by the control board 35 (for example, the heat generated by the heat-generating elements 3531) is efficiently dissipated from both sides of it along its thickness, the motor unit 3, intended for use in electric bicycles, can exhibit improved heat dissipation. In the third modification of the motor unit 3, the control board 35 can have improved heat dissipation, and the several heat-generating elements 3531 on the printed circuit board 354 can be arranged closer together, which reduces the size of the control board 35. As shown in Fig. 9, in the third modification of the motor unit 3, when viewed along the thickness of the control board 35 (i.e., viewed in the clockwise / counterclockwise direction), the first heat dissipation section 414 and the second heat dissipation section 424 are both positioned such that they overlap with the heat-generating elements 3531. This allows the heat generated by the heat-generating elements 3531 to be efficiently dissipated via the first heat dissipation section 414 and the second heat dissipation section 424. The first heat dissipation section 414 and the second heat dissipation section 424 can each be positioned such that they partially overlap with the heat-generating elements 3531. As shown in Fig. 9, the first heat dissipation section 414, viewed along the thickness of the control board 35, is positioned such that it overlaps with the second heat dissipation section 424. In the third modification of the motor unit 3, a section of the control board 35 (in particular, a side edge section of the control board 35 located further away from the input shaft 6) is enclosed layer by layer from both sides between the first heat dissipation section 414 and the second heat dissipation section 424. This not only improves the heat dissipation capacity of the control board 35 but also allows the control board 35 to be more securely mounted, thus improving the vibration resistance of the motor unit 3. The first heat dissipation section 414 must be arranged such that it overlaps at least partially with the second heat dissipation section 424. In the third embodiment of the motor unit 3, the thermally conductive element 9 includes both the first thermally conductive layer 91 and the second thermally conductive layer 92. However, this is only an example for the purposes of this disclosure and should not be interpreted as limiting. Alternatively, the thermally conductive element 9 can include either the thermally conductive layer 91 or the second thermally conductive layer 92, omitting the other layer. If the thermally conductive element 9 does not include the first thermally conductive layer 91, the first heat dissipation section 414 is in direct contact with the first surface 351 of the control board 35. If the thermally conductive element 9 does not include the second thermally conductive layer 92, the second heat dissipation section 424 is in direct contact with the second surface 352 of the control board 35. Furthermore, in the third modification of the motor unit 3, the first thermally conductive layer 91 and the second thermally conductive layer 92 are formed from mutually distinct layer elements. However, this is only an example for the purposes of the present disclosure and should not be interpreted restrictively. Alternatively, the first thermally conductive layer 91 and the second thermally conductive layer 92 can also be formed from the same layer element. This means that a portion of the layer element forming the thermally conductive element 9 can serve as the first thermally conductive layer 91, and another portion of the layer element can serve as the second thermally conductive layer 92. Note that the first to third variations described above are only a few of numerous variations. At least a part of the stator 53 and at least a part of the rotor 52 must be housed in the metallic shell 57. In the exemplary embodiment and the first to third variations thereof, a part of the stator 53 protrudes from the opening of the metallic shell 57. However, this is only an example for the present disclosure and should not be interpreted as limiting. Alternatively, the stator 53 can be completely housed in the metallic shell 57. In the exemplary embodiment and the first to third variations thereof, the electric bicycle equipped with the motor unit 3 is implemented as a so-called "electrically assisted bicycle". However, this is only an example for the present disclosure and should not be interpreted as limiting.Alternatively, the electric bicycle can also be an e-bike designed to propel the wheels 11 solely by the rotational force of the motor 5. Furthermore, according to the exemplary embodiment and the first to third variations thereof, the electric bicycle includes two wheels 11. However, the number of wheels 11 provided is not limited to a specific number, but can, for example, also be three. Furthermore, in the exemplary embodiment and the first to third variations thereof, the metallic shell 57 and the stator 53 are attached to one another using a thermal insertion technique. Optionally, an adhesive can also be applied between the metallic shell 57 and the stator 53 (for example, between the inner circumferential surface 570 of the metallic shell 57 and the outer circumferential surface 530 of the stator 53). This means that the metallic shell 57 and the stator 53 can be attached to one another not only by thermal insertion but also by means of an adhesive. Alternatively, the metallic shell 57 can be brought into pressure contact with the stator 53 using a technique other than thermal insertion (for example, by pressure fitting).In another alternative, the metallic shell 57 and the stator 53 can be attached to each other not only using the alternative technique, but also using an adhesive. Aspects As can be readily seen from the preceding description of an exemplary embodiment and its variations, a motor unit (3) is designed according to a first aspect for use in electric bicycles. The motor unit (3) comprises a motor (5) and a unit housing (4) into which the motor (5) is fitted. The motor (5) comprises: a stator (53); a rotor (52) arranged such that it is surrounded by the stator (53); a rotating shaft (51) attached to the rotor (52); and a metallic shell (57) that at least partially encloses the stator (53) and the rotor (52). The metallic shell (57) has an opening. An inner circumferential surface (570) of the metallic shell (57) is in pressure contact with the stator (53). In the motor unit (3), according to the first aspect, the heat generated by the stator (53) is transferred to the metallic shell (57), which is in pressure contact with the stator (53), and can be efficiently dissipated by the metallic shell (57). This improves the heat dissipation capacity of the motor unit (3) intended for use in electric bicycles. Additionally, according to the first aspect, the motor unit (3) can have an even further reduced overall weight when the metallic shell (57) is used. A motor unit (3) according to a second aspect can be implemented in combination with the first aspect. In the motor unit (3) according to the second aspect, at least part of an outer circumferential surface (530) of the stator (53) is a metallic surface (535). The inner circumferential surface (570) of the metallic shell (57) is in pressure contact with the metallic surface (535). In the motor unit (3), according to the second aspect, the inner circumferential surface (570) of the metallic shell (57) is in pressure contact with the metallic surface (535), whose properties make the surface sufficiently smooth and suitable for heat transfer. This allows heat to be easily transferred between the metallic shell (57) and the stator (53), resulting in excellent heat dissipation. A motor unit (3) according to a third aspect can be implemented in combination with the first or second aspect. In the motor unit (3) according to the third aspect, the stator (53) is formed entirely from resin, with the exception of a specific part thereof. This specific part comprises a section of the stator (53) with which the metallic shell (57) is in pressure contact. In the motor unit (3), according to the third aspect, the provision of the resin-molded section that partially covers the stator (53) not only reduces a significant increase in the temperature of the stator (53), but also vibrations. Additionally, the presence of the resin-molded section also increases the degree of insulation between the stator (53) and the metallic shell (57). A motor unit (3) according to a fourth aspect can be implemented in combination with one of the first to third aspects. The motor unit (3) according to the fourth aspect further includes a speed reducer (31) to which a torque from the motor (5) is transmitted. The speed reducer (31) is housed in the unit casing (4). In the motor unit (3) according to the fourth aspect, the motor (5) and the speed reducer (31) are provided as a unit. A motor unit (3) according to a fifth aspect can be implemented in combination with the fourth aspect. The motor unit (3) according to the fifth aspect further includes an O-ring (49) which is arranged between the unit housing (4) and the metallic shell (57). The metallic shell (57) has an opening edge section (574) against which the O-ring (49) is pressed. In the motor unit (3), according to the fifth aspect, the O-ring (49) can increase the extent of the close contact between the metallic shell (57) and the unit housing (4) and also reduce the transmission of vibrations. A motor unit (3) corresponding to a sixth aspect can be implemented in combination with the fifth aspect. In the motor unit (3) corresponding to the sixth aspect, the stator (53) includes a section (531) that projects from the metallic shell (57) through the opening. In the motor unit (3) according to the sixth aspect, the section (531) of the stator (53) projecting from the metallic shell (57) can serve as a guide if the O-ring (49) is or is fitted. A motor unit (3) corresponding to a seventh aspect can be implemented in combination with one of the first to sixth aspects. In the motor unit (3) corresponding to the seventh aspect, the metallic shell (57) is thermally introduced into the stator (53). In the motor unit (3) according to the seventh aspect, the metallic shell (57) can be brought into sufficiently close pressure contact with the stator (53). A motor unit (3) corresponding to an eighth aspect can be implemented in combination with one of the first to seventh aspects. In the motor unit (3) corresponding to the eighth aspect, the motor (5) further includes a bearing (552) designed to rotatably support the rotating shaft (51). A section of the metallic shell (57) has a recess (578) for receiving the bearing (552). In the motor unit (3) according to the eighth aspect, a structure for receiving the bearing (552) can be formed by part of the metallic shell (57), which further reduces the weight of the motor unit (3). An electric bicycle (1) according to a ninth aspect includes the motor unit (3) according to one of the first to eighth aspects; and at least one wheel (11) to which a rotational force is transmitted from the motor (5) of the motor unit (3). The electric bicycle (1) according to the ninth aspect can improve the heat dissipation capability of the motor unit (3) and also have a much lower weight. As can be readily seen from the preceding description of an exemplary embodiment and its variations (for example, among others, the third variation), a motor unit (3) according to a tenth aspect is designed for use in electric bicycles and comprises: a motor (5) having a rotating shaft (51); a unit housing (4) that partially houses the rotating shaft (51); an input shaft (6) arranged in the unit housing (4) such that it passes through the unit housing (4) and is rotatable about an axis (60); an input element (7) arranged around an outer circumferential surface of the input shaft (6) and designed to rotate together with the input shaft (6); an output element (8) arranged along the outer circumferential surface of the input shaft (6) and designed to rotate about the axis (60) when receiving a rotational force from the input element (7); and a control orThe control board (35) is housed in the unit housing (4) and is designed to control the rotation of the motor (5). The unit housing (4) includes: a first heat dissipation section (414) connected to a first surface (351) of the control board (35); and a second heat dissipation section (424) connected to a second surface (352) of the control board (35). The second surface (352) faces opposite the first surface (351). In the motor unit (3) according to the tenth aspect, the heat generated in the control board (35) can be efficiently dissipated from both sides via the first heat dissipation section (414) and the second heat dissipation section (424), which improves the heat dissipation capability of the motor unit (3) intended for use in electric bicycles. A motor unit (3) according to an eleventh aspect can be implemented in combination with the tenth aspect. The motor unit (3) according to the eleventh aspect further includes a thermally conductive element (9) arranged in the unit housing (4). The thermally conductive element (9) is arranged between the first heat dissipation section (414) and the control board (35) and / or between the second heat dissipation section (424) and the control board (35). In the case of the motor unit (3) according to the eleventh aspect, the heat generated in the control board (35) can be dissipated more efficiently by the thermally conductive element (9). A motor unit (3) corresponding to a twelfth aspect can be implemented in combination with the eleventh aspect. In the motor unit (3) corresponding to the twelfth aspect, the control board (35) includes an electrical component (353). The thermally conductive element (9) is in contact with the electrical component (353). In the motor unit (3) according to the twelfth aspect, the heat generated by the electrical component board (353) can be efficiently dissipated by the thermally conductive element (9). A motor unit (3) corresponding to a thirteenth aspect can be implemented in combination with one of the tenth to twelfth aspects. In the motor unit (3) corresponding to the thirteenth aspect, the control board (35) includes a heat-generating element (3531). At least one of the first heat dissipation section (414) or the second heat dissipation section (424) is arranged such that, when viewed along the thickness of the control board (35), it overlaps with the heat-generating element (3531). In the case of the motor unit (3) according to the thirteenth aspect, the heat generated by the heat-generating element (3531), whose temperature tends to increase very noticeably on the control board (35), can be dissipated even more efficiently. A motor unit (3) corresponding to a fourteenth aspect can be implemented in combination with one of the tenth to thirteenth aspects. In the motor unit (3) corresponding to the fourteenth aspect, the first heat dissipation section (414) is arranged such that, when viewed along the thickness of the control board (35), it overlaps with the second heat dissipation section (424). In the motor unit (3), as described in the fourteenth aspect, the control board (35) is enclosed in layers on both sides between the first heat dissipation section (414) and the second heat dissipation section (424). This not only improves heat dissipation but also allows the control board (35) to be more securely mounted, which may increase the vibration resistance of the motor unit (3). An electric bicycle (1) according to a fifteenth aspect includes the motor unit (3) according to one of the tenth to fourteenth aspects; and at least one wheel (11) to which a rotational force is transmitted from the motor (5) of the motor unit (3). The electric bicycle (1) according to the fifteenth aspect can improve the heat dissipation capability of the motor unit (3) intended for use in electric bicycles. Reference symbol list 1 Electric bicycle 11 Wheel 3 Motor unit 31 Speed ​​reducer 4 Unit housing 49 O-ring 5 Motor 51 Drive shaft 52 Rotor 53 Stator 530 Outer circumferential surface 535 Metallic surface 552 Bearing 57 Metallic shell 570 Inner circumferential surface 574 Opening edge section 578 Recess QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature WO 2014 / 184826 A1

[0004]

Claims

Motor unit (3) for use in an electric bicycle, the motor unit comprising: a motor (5) having a rotating shaft (51); a unit housing (4) that at least partially houses the motor (5), the unit housing (4) having a first subdivision part (41) and a second subdivision part (42); an input shaft (6) arranged in the unit housing (4), passing through the unit housing (4) and rotatable about an axis (60); an input body (7) arranged about an outer circumferential surface of the input shaft (6) and configured to rotate together with the input shaft (6); an output body (8) arranged along the outer circumferential surface of the input shaft (6) and configured to rotate about the axis (60) when receiving a rotational force from the input body (7); a freewheel clutch (32) arranged such that it is located between the input body (7) and the output body (8). is;a control or regulating board (35) housed in the unit housing (4) and designed to control or regulate the rotation of the motor (5); a first bearing (552) arranged to rotatably support the rotating shaft (51); a bearing retaining element (578) arranged to hold the first bearing (552); and a second thermally conductive element (92) arranged in the unit housing (4), wherein the second subdivision part (42) has a second heat dissipation section (424) which is connected to the control board (35) via the second thermally conductive element (92), a section of the second subdivision part (42) forms the second heat dissipation section (424) which curves inwards in the unit housing (42), the bearing retaining element (578) is attached to the first subdivision part (41), the input body (7) includes: a first input body (71) which is coupled to the input shaft (6);and a second input body (72) which is coupled to the first input body (71) and is designed to transmit a rotational force to the output body (8), wherein the second input body (72) is arranged radially inwards from the freewheel clutch (32), and wherein the output body (8) is arranged radially outwards from the freewheel clutch (32). Motor unit (3) according to claim 1, wherein the motor (5) further comprises a stator (53), and the second heat dissipation section (424) and the second thermally conductive element (92) are arranged such that they overlap with the stator (53) when viewed along the thickness of the control board (35). Motor unit (3) according to claim 1 or 2, wherein the output body (8) is cylindrical and an axial end section of the output body (8) passes through a through hole (421) of the second subdivision part (42) and protrudes from the unit housing (4). Motor unit (3) according to one of claims 1 to 3, wherein the second heat dissipation section (424) is located further away from the input shaft (6) than a speed reducer (31) which is housed in the unit housing (4). Motor unit (3) according to one of claims 1 to 4, wherein the first bearing (525) rotatably supports an axial end section of the rotating shaft (51). Motor unit (3) according to one of claims 1 to 5, further comprising a first thermally conductive element (91), wherein the first subdivision part (41) has a first heat dissipation section (441) which is connected to the control board (35) via the first thermally conductive element (91), wherein a section of the first subdivision part (41) forms the first heat dissipation section (441) which curves inwards in the unit housing (4). Motor unit (3) according to claim 6, wherein the first heat dissipation section (414) is arranged such that it overlaps with the second heat dissipation section (424) when viewed along the thickness of the control board (35). Motor unit (3) for use in an electric bicycle, the motor unit comprising: a motor (5) having a rotating shaft (51); a unit housing (4) that at least partially houses the motor (5), the unit housing (4) having a first subdivision part (41) and a second subdivision part (42); an input shaft (6) arranged in the unit housing (4), passing through the unit housing (4) and rotatable about an axis (60); an input body (7) arranged about an outer circumferential surface of the input shaft (6) and configured to rotate together with the input shaft (6); an output body (8) arranged along the outer circumferential surface of the input shaft (6) and configured to rotate about the axis (60) when receiving a rotational force from the input body (7); a freewheel clutch (32) arranged such that it is located between the input body (7) and the output body (8). is;a control or regulating board (35) housed in the unit housing (4) and designed to control or regulate the rotation of the motor (5); and a second thermally conductive element (92) arranged in the unit housing (4), wherein the second subdivision part (42) has a second heat dissipation section (424) which is connected to a second surface (352) of the control or regulating board (35) via the second thermally conductive element (92), a section of the second subdivision part (42) forming the second heat dissipation section (424) which curves inwards in the unit housing (42), the input body (7) comprising: a first input body (71) coupled to the input shaft (6); and a second input body (72) which is coupled to the first input body (71) and designed to transmit a rotational force to the output body (8). Motor unit (3) according to claim 8, wherein the output body (8) is cylindrical and an axial end section of the output body (8) passes through a through hole (421) of the second subdivision part (42) and protrudes from the unit housing (4). Motor unit (3) according to claim 8 or 9, further comprising: a first bearing (525) rotatably supporting an axial end section of the rotary shaft (51). Motor unit (3) according to claim 10, wherein the motor (5) comprises: a stator (53), a rotor (52) arranged such that it is surrounded by the stator (53), and a metallic shell (57) having an opening and designed to at least partially accommodate the stator (53) and the rotor (52), wherein a section of the metallic shell (57) has a recess (578) designed to receive the bearing (552). Motor unit (3) according to one of claims 8 to 11, further comprising a first thermally conductive element (91), wherein the first subdivision part (41) has a first heat dissipation section (441) which is connected to a first surface (351) of the control or regulating board (35) via the first thermally conductive element (91), and a section of the first subdivision part (41) forms the first heat dissipation section (441) which curves inwards in the unit housing (4). Motor unit (3) according to claim 12, wherein the first heat dissipation section (414) is arranged such that, when viewed along the thickness of the control board (35), it overlaps with the second heat dissipation section (424); and / or the second surface (352) of the control board (35) is opposite to the first surface (351) of the control board (35). Motor unit (3) for use in electric bicycles, the motor unit (3) comprising: a motor (5) having a rotating shaft (51); a unit housing (4) partially enclosing the rotating shaft (51), the unit housing (4) being made of a metallic material; an input shaft (6) arranged in the unit housing (4), passing through the unit housing (4) and rotatable about an axis (60); an input element (7) arranged around an outer circumferential surface of the input shaft (6) and configured to rotate with the input shaft (6); an output element (8) arranged along the outer circumferential surface of the input shaft (6) and configured to rotate about the axis (60) when receiving a rotational force from the input element (7); a control board (35) housed in the unit housing (4) and configured to control the rotation of the motor (5). orto regulate; and motor parts housed within a metallic shell (57), wherein the metallic shell (57) is coupled to the unit housing (4), wherein a rotational force of the rotating shaft (51) is transmitted to the output body (8) via a gear wheel (312) arranged within the unit housing (4), the unit housing (4) comprising a first subdivision part (41) and a second subdivision part (42), the first subdivision part (41) comprising, as an integral part of the first subdivision part (41), a first heat dissipation section (414) connected to a first surface (351) of the control or regulating board (35) in a thickness direction of the control or regulating board (35), the second subdivision part (42) comprising, as an integral part of the second subdivision part (42), a second heat dissipation section (424) connected to a surface (351) of the first subdivision part (42) (351) opposite or opposite to the control board (35)is connected to the opposite second surface (352) of the control or regulating board (35), a section of the first subdivision part (41) is thicker than a surrounding section thereof, wherein this thicker section of the first subdivision part (41) forms the first heat dissipation section (414) which curves inwards in the unit housing (4). Motor unit (3) according to claim 14, further comprising: a thermally conductive element (9) arranged in the unit housing (4), wherein the thermally conductive element (9) is arranged between the first heat dissipation section (414) and the control or regulating board (35) and / or between the second heat dissipation section (424) and the control or regulating board (35). Motor unit (3) according to claim 15, wherein the control board (35) includes an electrical component (353), and the thermally conductive element (9) is in contact with the electrical component (353). Motor unit (3) according to one of claims 14 to 16, wherein the control board (35) includes a heat-generating element (3531), and at least one of the first heat dissipation section (414) or the second heat dissipation section (424) is arranged such that it overlaps with the heat-generating element (3531) when viewed in the thickness direction of the control board (35). Motor unit (3) according to one of claims 14 to 17, wherein the first heat dissipation section (414) is arranged such that it overlaps with the second heat dissipation section (424) when viewed in the thickness direction of the control or regulating board (35). Motor unit (3) according to claim 15, wherein the control board (35) includes a heat-generating element (3531), at least one of the first heat dissipation section (414) or the second heat dissipation section (424) is arranged such that, when viewed in the thickness direction of the control board (35), it overlaps with the heat-generating element (3531), the second heat dissipation section (424) is connected to the control board (35) via a second thermally conductive element (9) which is included in the thermally conductive element (9), and several heat-generating elements (3531) are in contact with the second thermally conductive element (9). Motor unit (3) according to claim 19, wherein the first heat dissipation section (414) is connected to the control board (35) via a first thermally conductive element (9) which is included in the thermally conductive element (9), and several heat-generating elements (3531) are in contact with the first thermally conductive element (9). Motor unit (3) according to one of claims 14 to 20, wherein a section of the second subdivision part (42) is designed such that it is recessed inwards in relation to a surrounding section thereof, and the bottom of the recessed section of the second subdivision part (42) forms the second heat dissipation section (424) which curves inwards in the unit housing (4). Motor unit according to one of claims 14 to 21, wherein a side edge section of the control or regulating board (35) located further away from the input shaft (6) is enclosed layer by layer between the first heat dissipation section (414) and the second heat dissipation section (424) from both sides. Motor unit (3) according to one of claims 14 to 22, wherein the output body (8) is a cylindrical element and is rotatably arranged along the outer circumferential surface of the input shaft (6), and an end section of the output body (8) passes through a through hole (421) of the second subdivision part (42) and protrudes from the unit housing (4). Electric bicycle (1) comprising the motor unit (3) according to any one of claims 1 to 23.

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