Motor Unit

Abstract

To provide a motor unit and an electric vehicle which prevents tooth hammer noise by engagement of output gears.SOLUTION: A motor unit 3 includes a case 4, a motor 5, an output body 8, an input shaft 6, and an output gear 9. The motor 5 is stored in the case 4. The output body 8 is arranged so as to penetrate through the case 4 in a shaft line 600 direction and is rotatable around the shaft line 600. The input shaft 6 is arranged so as to penetrate through the case 4 in a shaft line 600 direction and is rotatable around the shaft line 600. The output gear 9 is mounted on the output body 8, and receives a rotational force of the motor 5 and transmits a rotational force to the output body 8. The output gear 9 has a tooth part 91 formed of the resin.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a motor unit. to Regarding. [Background technology]

[0002] Conventionally, there is known an electrically assisted bicycle equipped with a motor drive unit (see, for example, Patent Document 1). The motor drive unit disclosed in Patent Document 1 includes a unit case, a motor, an interlocking body that is fitted into a sprocket, and a reduction gear. A reduction small diameter gear portion attached to the reduction gear small diameter support shaft portion of the reduction gear meshes with a large diameter gear portion formed integrally with the interlocking body to transmit the rotational torque of the motor to the large diameter gear portion of the interlocking body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 184826 Summary of the Invention [Problem to be solved by the invention]

[0004] In the past, in electrically assisted bicycles such as those described above, the small diameter reduction gear portion of the reduction gear and the large diameter gear portion of the interlocking body were both usually made of metal, which caused a problem in that the small diameter reduction gear portion and the large diameter gear portion meshed with each other, easily generating teeth rattle noise.

[0005] In view of the above-mentioned conventional problems, the present disclosure provides a motor unit in which gear rattle noise is unlikely to occur due to meshing of output gears. to The purpose is to provide. [Means for solving the problem]

[0006] In order to solve the above problems, a motor unit according to one embodiment includes a case, a motor, and An input shaft, a reduction mechanism, Output body and ,of The motor is accommodated in the case. Input shaft penetrates the case in the axial direction and rotates around the axis By human power It is arranged to be rotatable. The reduction mechanism reduces the speed of the rotation of the motor and transmits it. The rotational force of the motor is transmitted to the output body via the reduction mechanism. The reduction mechanism has a gear that rotates by the rotational force of the motor. The gear includes a base containing metal, and a tooth portion that is located on the outer periphery of the base and is formed of resin. The reduction mechanism has a first gear that rotates by receiving the rotational force of the motor, a second gear that is separate from the first gear, and a third gear that rotates by receiving the rotational force of the second gear as the gear. The tooth portion of the second gear is formed of metal. Effect of the Invention

[0008] The motor unit according to the above aspect of the present disclosure to In this case, the meshing of the output gears makes it difficult for teeth rattle noise to occur. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of the electric bicycle according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a frame and a motor unit of the electric bicycle. [Diagram 3] FIG. 3 is a cross-sectional view taken along a plane passing through the axes of an input shaft of the motor unit, a rotating shaft of the motor, and a rotating transmission shaft of the reduction gear mechanism. [Figure 4] FIG. 4 is an enlarged perspective view of a part of an output gear of the motor unit. [Diagram 5] FIG. 5 is a cross-sectional view taken along a plane passing through the axes of the input shaft of the motor unit, the rotating shaft of the motor, and the rotating transmission shaft of the reduction gear mechanism according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present disclosure relates to a motor unit and a two-wheeled vehicle, and more specifically to a motor unit including a case, a motor, an output body, and an output gear, and to an electric bicycle such as an electrically assisted bicycle or an electric motorcycle including this motor unit.

[0011] A first embodiment of a motor unit and an electric bicycle according to the present disclosure will now be described with reference to Figs.

[0012] As shown in Fig. 1, the electric bicycle 1 includes a frame 10, wheels 11, and a motor unit 3. The electric bicycle 1 has a fixed direction of travel due to its design. In the following description, the direction of travel is defined as forward, and the opposite direction is defined as backward. Furthermore, the left and right directions refer to the left and right directions when facing forward.

[0013] The frame 10 supports a person (hereinafter, referred to as a rider) who rides the electric bicycle 1. The weight of the frame 10 and the rider is supported on the ground via a front wheel 111 and a rear wheel 112 that constitute the wheels 11.

[0014] 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. The frame 10 is made of a metal such as aluminum or stainless steel, but may contain a non-metallic material in part. Moreover, the entire frame 10 may be made of a non-metallic material, and the material of the frame 10 is not particularly limited.

[0015] As shown in FIG. 2, the head pipe 101 is a cylindrical member that opens generally in the vertical direction. Here, generally in the vertical direction means a direction that forms an angle of about 30 degrees or less with the vertical direction. As shown in FIG. 1, the handle post 12 is inserted into the head pipe 101 so as to penetrate from top to bottom. The handle post 12 is inserted into the head pipe 101 so as to be rotatable around the axial direction. 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 handle bar 122 is fixed to the upper end of the handle post 12. The handle bar 122 is provided with a hand operation unit for turning the electric power on and off, and a gear shift operation unit for changing the speed by a gear shift mechanism of the rear wheel 112.

[0016] As shown in Fig. 2, the upper pipe 102 is a tubular member extending generally rearward from the head pipe 101. The upper pipe 102 does not necessarily have to be straight. Note that generally rearward here means a direction forming an angle of about 40 degrees or less with the rear. The front end of the upper pipe 102 is fixed to the side wall on the rear side of the head pipe 101 by welding or the like. The rear end of the upper pipe 102 is fixed to the stand pipe 104.

[0017] The stand pipe 104 is a tubular member that opens generally in the vertical direction. The rear end of the upper pipe 102 is fixed to the front side wall near the upper end of the stand pipe 104 by welding or the like. A shaft extending downward from the saddle 13 is inserted into the opening at the upper end of the stand pipe 104, as shown in FIG. 1 . The saddle 13 is fixed to the stand pipe 104 by fixing this shaft to the stand pipe 104. The bracket 2 is fixed to the lower end of the stand pipe 104.

[0018] As shown in FIG. 2, the lower pipe 103 is a tubular member that extends obliquely downward generally rearward from the head pipe 101. The upper pipe 102 does not necessarily have to be straight. Note that "obliquely downward generally rearward" here means a direction that is lower than the rear and that is inclined downward from the direction in which the head pipe 101 extends. The front end of the lower pipe 103 is fixed by welding or the like to a portion of the rear side wall of the head pipe 101 that is lower than the portion to which the upper pipe 102 is fixed. A bracket 2 is fixed to the rear end of the lower pipe 103. The bracket 2 is part of the frame 10 and supports the motor unit 3.

[0019] A motor unit 3 is fixed to the underside of the bracket 2 and is supported by the bracket 2. Between the inner surface of the bracket 2 and the outer surface of the motor unit 3, a wiring space 20 is formed.

[0020] The rear end of the down pipe 103 is fixed to the front end of the bracket 2 by fitting (including shrink fitting), fastening, welding, or the like. In the first embodiment, a through hole 25 that penetrates vertically is formed in the front end of the bracket 2, and a cylindrical portion 251 protrudes from the periphery of the through hole 25. The rear end of the down pipe 103 is fitted over this cylindrical portion 251.

[0021] The lower end of the standpipe 104 is fixed to the intermediate portion of the bracket 2 in the front-rear direction by fitting (including shrink fitting), fastening, welding, or the like. In the first embodiment, a through hole 26 that penetrates vertically is formed in the intermediate portion of the bracket 2, and a cylindrical portion 261 protrudes from the portion surrounding the through hole 26. The lower end of the standpipe 104 is fitted over this cylindrical portion 261.

[0022] The front end of the chain stay 106 is fixed to the rear end of the bracket 2 by fitting (including shrink fitting), fastening, welding, or the like. The chain stay 106 is two hollow or solid members extending generally rearward from the bracket 2. In the first embodiment, the front end of the cylindrical chain stay 106 is fixed to the rear end of the bracket 2 by welding. Also, a through hole 27 that penetrates vertically is formed at a position of the bracket 2 corresponding to the internal space of the chain stay 106.

[0023] 1, the front end of the seat stay 105 is fixed to the rear end of the upper pipe 102 by fitting (including shrink fitting), fastening, welding, or the like. The seat stays 105 are two hollow or solid members extending roughly rearward from near the upper end of the vertical pipe 104. In the first embodiment, the front end of the cylindrical seat stay 105 is fixed by welding or the like. The rear end of the seat stay 105 is fixed to the rear end of the chain stay 106, and a rear wheel 112 is rotatably attached to this portion.

[0024] As shown in FIG. 2, the bracket 2 and the lower pipe 103 have a battery mounting section 16 on which a battery 15 (see FIG. 1) for supplying power to the motor unit 3 is mounted. The battery mounting section 16 has a lower support section 161 formed on the bracket 2 and an upper support section 162 formed on the lower pipe 103. The lower support section 161 is mounted so that the lower end of the battery 15 does not easily fall off, and supports the battery 15. The lower support section 161 also has a plurality of terminals that are electrically connected to a plurality of battery terminals for power supply or signals that are formed on the lower end of the battery 15. One end of wiring 163 is electrically connected to each of the plurality of terminals.

[0025] The upper support portion 162 has an upper end portion of the battery 15 attached thereto, and has a locking device that locks the battery 15 to prevent the battery 15 from falling off.

[0026] Further, through lower pipe 103 and wiring space 20, gear shift wires 17 connecting the gear shift operation part and the gear shift mechanism and brake wires are passed.

[0027] The motor unit 3 will be described below with reference to Fig. 3. The motor unit 3 includes a case 4, a motor 5, an output body 8, and an output gear 9. In the first embodiment, the motor unit 3 further includes an input shaft 6, an input body 7, and a reduction mechanism 31.

[0028] The case 4 constitutes an outer shell of the motor unit 3. The case 4 accommodates devices such as the reduction gear mechanism 31 in an accommodation space formed inside. The case 4 is mainly made of a metal such as aluminum or stainless steel, but a non-metal may also be used, and the material of the case 4 is not particularly limited.

[0029] The case 4 is divided into a first divided body 41 located on the left side and a second divided body 42 located on the right side. The first divided body 41 and the second divided body 42 are combined to form the case 4. The case 4 will be described in more detail later.

[0030] In the first split body 41, the internal storage space is open to the right. The first split body 41 also has a motor cup 57. The motor cup 57 protrudes to one side in the short side direction and stores the motor 5 therein. The motor cup 57 is attached to a part of the first split body 41. The motor cup 57 is fixed to the first split body 41 by a fastening member 571 made of a bolt.

[0031] The second divided body 42 has an internal storage space that is open to the left. The first divided body 41 and the second divided body 42 are aligned from the left and right so that their respective storage spaces are continuous, and are fixed to each other with fastening members made of bolts. The case 4 is formed by fixing the first divided body 41 and the second divided body 42 to each other. The size, shape, thickness, etc. of the case 4 are not particularly limited. The storage space formed inside the case 4 may or may not be sealed.

[0032] The motor 5 is attached to the case 4. More specifically, the motor 5 is mainly housed in a motor cup 57 attached to the first divided body 41. The motor 5 is housed in the case 4. The motor 5 has a rotating shaft 51, a rotor 52 that rotates integrally with the rotating shaft 51, and a stator 53. The rotor 52, the stator 53, and a part of the rotating shaft 51 are located in the motor cup 57. The rotating shaft 51 is housed rotatably so that the axial direction faces the left-right direction. The rotating shaft 51 protrudes from the stator 53 to one side (to the right in the first embodiment), and a tooth portion 54 that meshes with the reduction mechanism 31 is formed on the outer surface of the protruding part. The right end of the rotating shaft 51 is supported by a rotating shaft support bearing 551 arranged in the second divided body 42. The left end of the rotating shaft 51 does not particularly protrude from the stator 53, and is supported by a rotating shaft support bearing 552 arranged in the motor cup 57.

[0033] The input shaft 6 penetrates the case 4 in the direction of an axis 600 (left-right direction in the first embodiment) and is arranged to be rotatable around the axis 600 of the input shaft 6. The input shaft 6 has an input shaft body 60 and an input body 7. In the first embodiment, the input shaft body 60 is made of a solid member, but may be made of a hollow member.

[0034] The case 4 has a first bearing 45, which rotatably supports the input shaft body 60, at one end side in the direction of the axis 600 (the left end side in the first embodiment). An input shaft hole 411 through which the input shaft body 60 passes is formed in the first divided body 41, and the first bearing 45 is disposed in this input shaft hole 411. In the first embodiment, the first bearing 45 is configured by a ball bearing. Note that the first bearing 45 is not limited to a ball bearing and various other bearings, such as a roller bearing, can also be used.

[0035] The case 4 also has a second bearing 46 that rotatably supports the output body 8 at the other end side in the direction of the axis 600 (the right end side in the first embodiment). An input shaft hole 421 through which the input shaft body 60 passes is formed in the second divided body 42, and the second bearing 46 is disposed in this input shaft hole 421. In the first embodiment, the input shaft body 60 is indirectly supported by the second bearing 46 via the output body 8. In the first embodiment, the second bearing 46 is configured by a ball bearing. Note that the second bearing 46 is not limited to a ball bearing and various other bearings such as a roller bearing can also be used.

[0036] 1, one end of a crank arm 18 is fixed to the end of the input shaft body 60. A pedal 181 is rotatably attached to the other end of the crank arm 18. The rider of the electric bicycle 1 can transmit human power to the input shaft body 60 by pedaling the pedal 181.

[0037] As shown in FIG. 3, the input body 7 is disposed along the outer circumferential surface of the input shaft body 60 and rotates integrally with the input shaft body 60. The input body 7 is a cylindrical member, and its axis 600 faces the left-right direction, and is disposed concentrically with the input shaft body 60. The length of the input body 7 in the left-right direction is shorter than the length of the input shaft body 60 in the left-right direction. The input body 7 and the input shaft body 60 have fitting portions 711, 61 in a part in the axis 600 direction, which fit with each other so as to be relatively unrotatable around the axis 600. In the first embodiment, the fitting portions 711, 61 made of a spline portion or a serration portion are formed on the left end portion of the input body 7 (more specifically, the first input body 71 described later) and the input shaft body 60 corresponding to this portion. The fitting portions 711, 61 may be configured to be fitted with a male screw and a female screw.

[0038] Furthermore, in the first embodiment, 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 body 60. The first input body 71 is located at a part of the input shaft body 60 in the left-right direction, and is housed in the first divided body 41. A fitting portion 711 that fits with the input shaft body 60 is formed at the left end of the first input body 71. A gap 70 is formed between the first input body 71 and the input shaft body 60 in a portion to the right of the fitting portion 711 at the left end of the first input body 71. This makes it easier to insert the input shaft body 60 into the cylindrical first input body 71.

[0039] The second input body 72 is connected to the first input body 71 at a position different from the first input body 71 in the direction of the axis 600 (to the right of the first input body 71 in the first embodiment) and transmits a rotational force to the output body 8. However, the second input body 72 may be partially located at the same position in the left-right direction as the first input body 71. In the first embodiment, the left end of the second input body 72 is located radially outside the right end of the first input body 71, and overlaps with each other in the radial direction. The first input body 71 and the second input body 72 have fitting portions 712, 721 that fit with each other so as to be relatively unrotatable around the axis 600. In the first embodiment, the fitting portions 712, 721 made of a spline portion or a serration portion are formed on the right end of the first input body 71 and the left end of the second input body 72. In this disclosure, "overlapping in the radial direction" refers to a state in which at least a part of each object overlaps when viewed in the radial direction.

[0040] The output body 8 is disposed rotatably around the axis 600 along the outer circumferential surface of the input shaft body 60, and penetrates the case in the direction of the axis 600. The output body 8 receives a rotational force from the input body 7. The output body 8 is a generally cylindrical member, and the axis 600 of the output body 8 faces the left-right direction, and is disposed concentrically with the input shaft body 60. The left-right length of the output body 8 is shorter than the left-right length of the input shaft body 60. The right end of the output body 8 protrudes outside the case 4 through an input shaft hole 421 formed in the second divided body 42. The output body 8 is supported by the second bearing 46 disposed in the second divided body 42. The output body 8, together with the input shaft body 60 and the input body 7, constitutes the rotating shaft unit 30. The rotating shaft unit 30 is supported by the case 4 via the first bearing 45 and the second bearing 46.

[0041] A front sprocket 191 is fixed by a lock ring 195 to a portion of the output body 8 protruding outside the case 4. The front sprocket 191 rotates integrally with the output body 8. In addition, as shown in FIG. 1, a rear sprocket 192 is fixed to the hub of the rear wheel 112. A chain 193 is wound between the front sprocket 191 and the rear sprocket 192.

[0042] As shown in FIG. 3, in the first embodiment, a one-way clutch 32 is disposed between the input body 7 and the output body 8. When a rotational force in a direction that accelerates the electric bicycle 1 in the traveling direction (hereinafter referred to as the acceleration direction) is applied to the input body 7, the one-way clutch 32 transmits the rotational force to the output body 8, and when a rotational force in a direction opposite to the acceleration direction is applied, the one-way clutch 32 does not transmit the rotational force to the output body 8. In addition, when a rotational force in the acceleration direction is applied to the output body 8 via a speed reduction mechanism 31 described later, the one-way clutch 32 does not transmit the rotational force to the input body 7. In the first embodiment, the one-way clutch 32 has a ratchet and is supplied with grease. Note that various types of one-way clutch 32 can be appropriately used and are not limited. For example, a roller type one-way clutch or a sprag type one-way clutch may be used.

[0043] Furthermore, in the first embodiment, the second input body 72 and the output body 8 overlap in a partial range in the direction of the axis 600. The one-way clutch 32 is provided between the overlapping second input body 72 and the output body 8.

[0044] The second bearing 46 overlaps with the one-way clutch 32 in the radial direction of the input shaft 60 over a portion of the direction of the axis 600. In the first embodiment, the second bearing 46 is located outside the one-way clutch 32.

[0045] An output gear 9 is attached to the output body 8. The output gear 9 becomes a part of the output body 8 and rotates integrally with the output body 8, receives the rotational force of the motor 5, and transmits the rotational force to the output body 8. In the first embodiment, the output gear 9 receives the rotational force of the motor 5 via a reduction mechanism 31, and transmits the rotational force to the output body 8. The output gear 9 has a tooth portion 91 of the reduction mechanism 31 on its outer circumferential surface. The output gear 9 will be described later.

[0046] The reduction gear 31 is housed in the case 4, and reduces the speed of rotation of the motor 5 and transmits it to the output body 8. The reduction gear 31 has a first transmission gear 311 and a second transmission gear 312. The outer diameter of the first transmission gear 311 is larger than the outer diameter of the second transmission gear 312. The number of teeth of the first transmission gear 311 is larger than the number of teeth of the second transmission gear 312. The second transmission gear 312 is formed of a metal such as steel.

[0047] The first transmission gear 311 meshes with the rotating shaft 51 of the motor 5 and rotates by the rotational force received from the rotating shaft 51. In the first embodiment, the first transmission gear 311 is made of a cylindrical member, and has teeth 313 formed on its outer circumferential surface to mesh with teeth 54 formed on the rotating shaft 51 of the motor 5. The first transmission gear 311 is disposed along the outer circumferential surface of the transmission rotating shaft 310 of the reduction mechanism 31. In the first embodiment, the first transmission gear 311 is configured to receive the rotational force directly from the rotating shaft 51 of the motor 5, but a gear may be interposed therebetween. The transmission rotating shaft 310 is formed of a metal such as steel.

[0048] The transmission rotation shaft 310 is rotatably housed in the case 4 so that the axial direction faces the left-right direction. The transmission rotation shaft 310 is located rearward of the rotation shaft 51 of the motor 5, and is disposed in approximately the same position in the left-right direction as the portion of the rotation shaft 51 that protrudes rightward from the stator 53. The transmission rotation shaft 310 may be disposed forward of the rotation shaft 51 of the motor 5. The right end of the transmission rotation shaft 310 is supported by a transmission rotation shaft support bearing 3141 disposed in the second division body 42. The left end of the transmission rotation shaft 310 is supported by a transmission rotation shaft support bearing 3142 disposed in the first division body 41.

[0049] The first transmission gear 311 is connected to the transmission rotation shaft 310 via a one-way clutch 315. When a rotational force in the acceleration direction is applied to the first transmission gear 311, the one-way clutch 315 transmits the rotational force to the transmission rotation shaft 310, and when a rotational force in the direction opposite to the acceleration direction is applied, the one-way clutch 315 does not transmit the rotational force to the transmission rotation shaft 310. Also, when a rotational force in the acceleration direction is applied to the transmission rotation shaft 310, the one-way clutch 315 does not transmit the rotational force to the first transmission gear 311.

[0050] A second transmission gear 312 is fixed to the right of the portion of the transmission rotation shaft 310 to which the one-way clutch 315 is fixed so as to rotate integrally with the transmission rotation shaft 310. The second transmission gear 312 meshes with the teeth portion 91 of the output gear 9 to transmit the rotational force received from the first transmission gear 311 via the transmission rotation shaft 310 to the teeth portion 91 of the output gear 9. The second transmission gear 312 has teeth 316 on its outer circumferential surface which meshes with the teeth portion 91 of the output gear 9.

[0051] When the rider pedals the pedals 181 of the electric bicycle 1, a rotational force in the acceleration direction is applied to the input shaft body 60. When the input shaft body 60 rotates, the first input body 71 and the second input body 72 rotate integrally with the input shaft body 60. The rotational force in the acceleration direction of the second input body 72 is applied to the output body 8 via the one-way clutch 32, and the output body 8 and the front sprocket 191 rotate in the acceleration direction. When the front sprocket 191 rotates in the acceleration direction, a rotational force in the acceleration direction is applied to the rear sprocket 192 via the chain 193, and the rear sprocket 192 and the rear wheel 112 rotate in the acceleration direction. This causes the electric bicycle 1 to move forward in the forward direction.

[0052] In addition, while the electric bicycle 1 is moving forward by human power, the rotational force from the motor 5 can be added to the output body 8 as an auxiliary force. This will be described in detail below. When the rotating shaft 51 of the motor 5 rotates in the acceleration direction, the first transmission gear 311 meshing with the rotating shaft 51 of the motor 5 rotates in the acceleration direction. The rotational force of the first transmission gear 311 in the acceleration direction is transmitted to the transmission rotating shaft 310 and the second transmission gear 312 fixed to the transmission rotating shaft 310 via the one-way clutch 315, and the second transmission gear 312 rotates in the acceleration direction. The rotational force of the second transmission gear 312 in the acceleration direction is transmitted to the output gear 9 meshing with the second transmission gear 312. That is, the output body 8 functions as a force combining body that combines the rotational force of the human power from the input body 7 and the rotational force from the motor 5. The motor unit 3 in the first embodiment is a so-called single-shaft motor unit 3.

[0053] Next, a case will be described where the motor 5 is not driven while the electric bicycle 1 is moving forward by human power. In this case, since the output body 8 is rotating in the acceleration direction, the second transmission gear 312 and the transmission rotation shaft 310 meshing with the output gear 9 rotate in the acceleration direction, but the rotational force of the transmission rotation shaft 310 in the acceleration direction is not transmitted to the first transmission gear 311 by the one-way clutch 315. As a result, when the motor 5 is not driven, the rotation shaft 51 and the rotor 52 are prevented from rotating.

[0054] In the electric bicycle 1, the rotational force from the motor 5 is controlled according to the torque applied to the input shaft body 60 and the rotation speed per unit time of the input shaft body 60. The torque applied to the input shaft body 60 is detected by a torque detection unit 33. The torque detection unit 33 is disposed within a partial range in the direction of the axis 600 along the outer circumferential surface of the rotating shaft unit 30.

[0055] In the first embodiment, a magnetostrictive generating section 331 having magnetic anisotropy is formed on the outer peripheral surface of the first input body 71. A coil 332 is disposed at a slight distance from the portion of the outer peripheral surface of the first input body 71 where the magnetostrictive generating section 331 is provided. The magnetostrictive generating section 331 and the coil 332 constitute a magnetostrictive torque sensor as the torque detection section 33. Various types of magnetostrictive torque sensors can be appropriately used as such a magnetostrictive torque sensor. Furthermore, the torque detection section 33 is not limited to a magnetostrictive torque sensor.

[0056] The torque detection unit 33 is disposed to the left of the first transmission gear 311, the second transmission gear 312, the one-way clutch 32, and the second bearing 46 in the direction of the axis 600.

[0057] The number of rotations per unit time of the input shaft 60 is detected by the rotation detection section 34. The rotation detection section 34 is disposed in a partial range along the outer circumferential surface of the rotating shaft unit 30 in the direction of the axis 600.

[0058] In the first embodiment, a rotor 341 having teeth and light transmitting portions formed between the teeth at regular intervals in the circumferential direction is fixed to the right of the coil 332 of the torque detection unit 33 on the outer peripheral surface side of the input body 7 so as to rotate integrally with the input body 7. Furthermore, an optical sensor 342 is arranged so as to sandwich the teeth of the rotor 341 from the left and right. The optical sensor 342 has a light emitting portion arranged on the left side of the teeth and a light receiving portion arranged on the right side of the teeth, but the positional relationship between the light emitting portion and the light receiving portion is not limited. As the rotation detection unit 34 having such a rotor 341 and an optical sensor 342, various ones can be appropriately used. In addition, the rotation detection unit 34 is not limited to one having the rotor 341 and the optical sensor 342.

[0059] The rotation detection unit 34 is located at the same position as the first transmission gear 311 in the direction of the axis 600, and is disposed to the left of the second transmission gear 312, the one-way clutch 32, and the second bearing 46. In this disclosure, "located at the same position in the direction of the axis 600" refers to a state in which at least a portion of them overlap when viewed in a direction perpendicular to the direction of the axis 600.

[0060] The motor unit 3 has a control board 35 disposed in a case 4 and having a control unit for controlling the motor 5. The control unit has, for example, 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). Various types of control unit can be appropriately used as this type of control unit, and detailed description will be omitted. The control unit controls the rotational force from the motor 5 based on the torque detected by the torque detection unit 33 and the number of rotations detected by the rotation detection unit 34.

[0061] The output gear 9 is attached by fitting the output body 8 inside. The inner surface of the output gear 9 and the outer surface of the output body 8 are connected by a spline connection or the like, but is not particularly limited to this. At least the teeth portion 91 of the output gear 9 is made of resin. In the first embodiment, the entire output gear 9 is made of resin. In contrast, the second transmission gear 312 and the transmission rotation shaft 310 that mesh with the teeth portion 91 are made of metal.

[0062] By forming the toothed portion 91 of the output gear 9 from resin, even if the toothed portion 91 meshes with a metal (the second transmission gear 312 in the first embodiment), collision between metals does not occur, and tooth rattle noise due to meshing of the toothed portion 91 of the output gear 9 is unlikely to occur. This makes it easy to configure a quiet motor unit 3.

[0063] Furthermore, in the first embodiment, when the rotating shaft 51 of the motor 5 is not rotating, the rotation speed of the input shaft 6 and the rotation speed of the output body 8 match. In other words, no gear is interposed between the input shaft 6 and the output body 8 for transmitting the rotational force of the input shaft 6 to the output body 8. For this reason, no gear rattle noise, which is likely to occur when gears are interposed, occurs, making it easier to configure an even quieter motor unit 3.

[0064] Furthermore, in the first embodiment, the rotational force of the motor 5 is transmitted to the output body 8 by so-called two-stage reduction via the first transmission gear 311 and the second transmission gear 312, so that large reduction in speed can be easily achieved.

[0065] In the first embodiment, the position of the second bearing 46 partially overlaps with the position of the tooth portion 91 of the output gear 9 in the radial direction of the output body 8. By overlapping the position of the second bearing 46 with the position of the tooth portion 91 in the direction of the axis 600 in this manner, it is easy to shorten the length of the motor unit 3 in the direction of the axis 600.

[0066] In the first embodiment, as shown in Fig. 4, the output gear 9 is a helical gear having a tooth portion 91 with helical teeth. This improves the meshing ratio of the tooth portion 91, making it easier to configure a quieter motor unit 3. The tooth portion 91 may be spur teeth.

[0067] In the first embodiment, the outer diameter D of the output gear 9 (twice the length from the rotational axis of the output gear 9 to the tip of the tooth portion 91) is 125 mm or less. This makes it possible to reduce the size of the motor unit 3 and the two-wheeled vehicle (electric bicycle 1). In particular, the so-called rear-center distance from the center of the rear wheel 112 to the axis 600 of the input shaft body 60 can be shortened, making it easier to handle the two-wheeled vehicle (electric bicycle 1).

[0068] Furthermore, it is more preferable that the outer diameter D of the output gear 9 is 98 mm or less. This allows the motor unit 3 and the two-wheeled vehicle (electric bicycle 1) to be further reduced in size, making the two-wheeled vehicle (electric bicycle 1) even easier to handle.

[0069] Furthermore, if the outer diameter D of the output gear 9 is 50 mm or more and less than 75 mm, the motor unit 3 can be made even more compact. Furthermore, by making the toothed portion 91 into a helical tooth with a torsion angle θ (the angle formed by the longitudinal direction of the helical tooth with respect to the width W direction) of 25° or less, or into a spur tooth, the posture stability of the gear 91 can be improved. Furthermore, if the length of the toothed portion 91 in the width W direction (coincident with the axis 600 direction) is 10 mm or more and 35 mm or less, the motor unit 3 can be made even more compact. In this case, it is preferable that the output torque of the output body 8 is 20 Nm or more and less than 50 Nm.

[0070] Furthermore, if the outer diameter D of the output gear 9 is 75 mm or more and 130 mm or less, the output torque of the output body 8 can be easily adjusted and increased. Furthermore, by setting the twist angle θ of the helical teeth of the tooth portion 91 (the angle formed by the longitudinal direction of the helical teeth with respect to the width W direction) to 10° or more and 25° or less, the durability of the tooth portion 91 can be improved and noise can be reduced. Furthermore, if the length of the tooth portion 91 in the width W direction (coincident with the axis 600 direction) is 19 mm or more and 35 mm or less, the output torque of the output body 8 can be more easily adjusted and increased. In this case, it is preferable that the output torque of the output body 8 is 50 Nm or more.

[0071] 3, in the first embodiment, length 521 in the axial direction (the same as the direction of axis 600) of rotor 52 is shorter than length 531 in the axial direction of stator 53. This makes it easier to shorten the length of the magnet of rotor 52 in the axial direction, and therefore easier to reduce costs.

[0072] Moreover, the output of the motor 5 can be changed by changing only the length 521 of the rotor 52 without changing the length 531 of the stator 53 .

[0073] Next, the motor unit 3 of the second embodiment will be described with reference to Fig. 5. The motor unit 3 of the second embodiment is mostly the same as the motor unit 3 of the first embodiment. Below, differences from the second embodiment will be mainly described.

[0074] 3, the one-way clutch 32 is disposed between the input body 7 and the output body 8. In contrast, the second embodiment differs in that the one-way clutch 32 is not disposed, and the input body 7 and the output body 8 have a connecting portion that connects the input body 7 and the output body 8 so that the input body 7 and the output body 8 rotate integrally.

[0075] A spline portion 73 consisting of projections and recesses arranged side by side in the circumferential direction is formed on the outer peripheral surface of the input body 7. Similarly, a spline portion 82 consisting of projections and recesses arranged side by side in the circumferential direction and meshing with the spline portion 73 is formed on the inner peripheral surface of the output body 8. The spline portion 73 and the spline portion 82 form a connecting portion.

[0076] By forming such a connecting portion on the input body 7 and the output body 8, it becomes easier to rotate the input body 7 and the output body 8 together. In particular, when a so-called coaster brake is adopted, such a connecting portion functions effectively.

[0077] The connecting portion is not limited to the spline portion 73 and the spline portion 82, but may be, for example, a portion in which a key groove is formed on the outer surface of the input body 7 and the output body 8 and a key is fitted into the key groove.

[0078] Next, modifications of the first and second embodiments will be described.

[0079] The rotational force of the motor 5 may be transmitted to the output body 8 without passing through the first transmission gear 311 and the second transmission gear 312.

[0080] The output gear 9 may be a spur gear instead of a helical gear.

[0081] The outer diameter D, width W, and twist angle in the case of a helical gear of the output gear 9 are not particularly limited.

[0082] In the first and second embodiments, the entire output gear 9 is made of resin. Alternatively, only the tooth portion 91 may be made of resin. The output gear 9 has a base and the tooth portion 91 attached to the outer circumferential surface of the base. The base contains more than 50% of a metal other than aluminum. As the metal other than aluminum, iron and SUS are preferable, but are not particularly limited. Furthermore, the base may be a sintered alloy of a metal containing more than 50% of a metal other than aluminum, such as iron or SUS.

[0083] Since aluminum has a large thermal expansion, the thermal expansion can be suppressed by using metals other than aluminum, such as iron, SUS, etc. In addition, since metals such as iron and SUS have a greater strength per volume than aluminum, it is easy to make the motor unit 3 more compact with the same strength.

[0084] As is clear from the first and second embodiments and their modified examples described above, the motor unit 3 of the first aspect includes a case 4, a motor 5, an output body 8, an input shaft 6, and an output gear 9. The motor 5 is housed in the case 4. The output body 8 passes through the case 4 in the axial direction (the same as the direction of the axis 600) and is arranged so as to be rotatable about the axis. The input shaft 6 passes through the case 4 in the direction of the axis 600 and is arranged so as to be rotatable about the axis 600. The output gear 9 is attached to the output body 8, and receives the rotational force of the motor 5 and transmits the rotational force to the output body 8. At least a tooth portion 91 of the output gear 9 is formed of resin.

[0085] According to the first aspect, since the tooth portion 91 of the output gear 9 is made of resin, even if the tooth portion 91 meshes with a metal, collision between metals does not occur, and tooth rattle noise due to meshing of the tooth portion 91 of the output gear 9 is unlikely to occur. This makes it easy to configure a quiet motor unit 3.

[0086] The motor unit 3 of the second aspect can be realized by combining with the first aspect. In the second aspect, the motor unit 3 further includes a transmission rotation shaft 310. The transmission rotation shaft 310 has a first transmission gear 311 that rotates in mesh with the rotation shaft 51 of the motor 5, and a second transmission gear 312 that meshes with the output gear 9 to transmit rotational force to the output gear 9.

[0087] According to the second aspect, the power is transmitted to the output body 8 by so-called two-stage reduction, so that large reduction in speed can be easily achieved.

[0088] The motor unit 3 of the third aspect can be realized by combining with the motor unit 3 of the first or second aspect. In the third aspect, the rotation speed of the input shaft 6 and the rotation speed of the output body 8 are the same.

[0089] According to the third aspect, the gear rattle noise that is likely to occur when gears are present does not occur, making it easier to configure an even quieter motor unit 3.

[0090] The motor unit 3 of the fourth aspect can be realized by combining with the third aspect. In the fourth aspect, the case 4 has a bearing (second bearing 46) that rotatably supports the rotating shaft unit 30 including the input shaft 6. The position of the bearing (second bearing 46) and the position of the output gear 9 overlap in the radial direction of the output body 8.

[0091] According to the fourth aspect, by overlapping the position of the second bearing 46 and the position of the tooth portion 91 in the radial direction of the output body 8, it is easy to shorten the length of the motor unit 3 in the direction of the axis 600.

[0092] The motor unit 3 of the fifth aspect can be realized by combining with any one of the first to fourth aspects. In the fifth aspect, the output gear 9 has a base and a tooth portion 91 attached to the outer circumferential surface of the base. The base contains more than 50% of a metal other than aluminum.

[0093] According to the fifth aspect, it is easy to suppress thermal expansion of the output gear 9, and it is also easy to make the motor unit 3 compact.

[0094] The motor unit 3 of the sixth aspect can be realized by combining with any one of the aspects 1 to 5. In the sixth aspect, the outside diameter of the output gear 9 is 125 mm or less.

[0095] According to the sixth aspect, the motor unit 3 can be made smaller.

[0096] The motor unit 3 of the seventh aspect can be realized by combining with any one of the first to sixth aspects. In the seventh aspect, the tooth portion 91 is a helical tooth.

[0097] According to the seventh aspect, the meshing ratio of the tooth portion 91 is improved, making it easier to configure a quieter motor unit 3.

[0098] The motor unit 3 of the eighth aspect can be realized by combining with any one of the aspects 1 to 7. In the eighth aspect, the outside diameter of the output gear 9 is 98 mm or less.

[0099] According to the eighth aspect, the motor unit 3 can be made smaller.

[0100] The electric bicycle 1 of the ninth aspect is realized by combining with any one of the first to eighth aspects. The electric bicycle 1 of the ninth aspect includes the motor unit 3 of any one of the first to eighth aspects.

[0101] According to the ninth aspect, it is easy to provide an electric bicycle 1 equipped with a quiet motor unit 3. [Explanation of symbols]

[0102] 1. Electric bicycle 3 Motor unit 30 Rotating shaft unit 310 Transmission Rotating Shaft 311 First transmission gear 312 Second transmission gear 4 Cases 46 No. 2 bearing 5 Motor 51 Rotation axis 6 Input shaft 600 axis 8 Output Body 9 Output gear 91 Teeth

Claims

1. Case and A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis by human power; a reduction mechanism that reduces the speed of rotation of the motor and transmits the reduced speed; an output body to which a rotational force of the motor is transmitted via the reduction mechanism, the reduction mechanism has a gear that rotates by a rotational force of the motor, the gear includes a base portion containing metal, and a tooth portion located on an outer periphery of the base portion and formed of resin, The reduction mechanism includes: a first gear that rotates by receiving a rotational force of the motor; A second gear different from the gear; a third gear that rotates by receiving a rotational force of the second gear, The teeth of the second gear are made of metal. Motor unit.

2. A case, a motor housed in the case and having a rotating shaft on which a motor tooth portion is formed; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis by human power; a reduction mechanism that reduces the speed of rotation of the motor and transmits the reduced speed; an output body to which a rotational force of the motor is transmitted via the reduction mechanism, the reduction mechanism has a gear that rotates by a rotational force of the motor, the gear includes a base portion containing metal, and a tooth portion located on an outer periphery of the base portion and formed of resin, The reduction mechanism includes: a first gear that rotates by receiving a rotational force of the motor teeth portion formed on the rotary shaft of the motor; A second gear different from the gear; a third gear that rotates by receiving a rotational force of the second gear, The teeth of the second gear are made of metal. Motor unit.

3. The output body rotates by the rotational force of the input shaft and the rotational force of the motor.

3. The motor unit according to claim 1 or 2.

4. The width of the tooth portion of the second gear is greater than the width of the tooth portion of the third gear. The motor unit according to claim 1 .

5. The teeth of the third gear are helical teeth.

5. A motor unit according to claim 1 or 4.

6. The twist angle of the helical teeth is greater than or equal to 10° and less than or equal to 25°. The motor unit according to claim 5.

7. The reduction mechanism has a one-way clutch. The motor unit according to any one of claims 1 to 6.

8. The second gear is rotatable by the rotation of the first gear. The motor unit according to claim 1 .

9. The second gear is rotatable by the rotation of the first gear. The motor unit according to claim 2.

10. The reduction mechanism includes a transmission rotation shaft, The first gear and the second gear are attached to the transmission rotation shaft. The motor unit according to claim 8.

11. The reduction mechanism includes a transmission rotation shaft, the first gear and the second gear are attached to the transmission rotation shaft, the case is disposed on one end side of the transmission rotation shaft in an axial direction thereof, and a first transmission rotation shaft support bearing is disposed on one end side of the transmission rotation shaft so as to rotatably support the transmission rotation shaft; a second transmission rotating shaft support bearing located on the other end side of the transmission rotating shaft in the axial direction and rotatably supporting the transmission rotating shaft, The first gear is mounted between the first transmission rotating shaft support bearing and the second transmission rotating shaft support bearing. The motor unit according to claim 2.

12. The motor has a motor rotating shaft, The first gear is rotatable by the rotation of the motor rotation shaft. The motor unit according to claim 8 or 10.

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