WO2020195984A1

WO2020195984A1 - Motor unit and electric bicycle

Info

Publication number: WO2020195984A1
Application number: PCT/JP2020/011269
Authority: WO
Inventors: 将史川上; 健斗奥田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2019-03-22
Filing date: 2020-03-13
Publication date: 2020-10-01
Also published as: JP2023126597A; JP7325016B2; JP2020152357A

Abstract

Provided are: a motor unit in which engagement of an output gear does not readily produce rattling; and an electric bicycle. A motor unit (3) that comprises a case (4), a motor (5), an output body (8), an input shaft (6), and an output gear (9). The motor (5) is housed inside the case (4). The output body (8) is inserted through the case (4) in a shaft line (600) direction and can rotate around the shaft line (600). The input shaft (6) is inserted through the case (4) in the shaft line (600) direction and can rotate around the shaft line (600). The output gear (9) is attached to the output body (8), receives rotational force from the motor (5), and transmits the rotational force to the output body (8). At least tooth parts (91) of the output gear (9) are formed from resin.

Description

Motor unit and electric bicycle

This disclosure relates to a motor unit and an electric bicycle.

Conventionally, an electrically assisted bicycle equipped with a motor drive unit is known (see, for example, Patent Document 1). The motor drive unit disclosed in Patent Document 1 includes a unit case, a motor, an interlocking body fitted in a sprocket, and a reduction gear. The small-diameter deceleration gear attached to the small-diameter support shaft of the deceleration gear meshes with the large-diameter gear integrally formed with the interlocking body to transfer the rotational torque of the motor to the large-diameter gear of the interlocking body. introduce.

Conventionally, in the electric assisted bicycle as described above, both the small-diameter gear portion for deceleration of the deceleration gear and the large-diameter gear portion of the interlocking body are usually formed of metal. Therefore, there is a problem that the small-diameter gear portion for reduction and the large-diameter gear portion mesh with each other, and a rattling noise is likely to occur.

International Publication No. 2014/184926

In view of the above-mentioned conventional problems, it is an object of the present disclosure to provide a motor unit and an electric bicycle that are less likely to generate toothing noise due to meshing of output gears.

In order to solve the above problems, one form of the motor unit includes a case, a motor, an output body, an input shaft, and an output gear. The motor is housed in the case. The output body is rotatably arranged around the axis through the case in the axial direction. The input shaft is rotatably arranged around the axis through the case in the axial direction. The output gear is attached to the output body, receives the rotational force of the motor, and transmits the rotational force to the output body. At least the teeth of the output gear are made of resin.

In order to solve the above problem, one form of electric bicycle is provided with the motor unit.

FIG. 1 is a side view of the electric bicycle according to the first embodiment. FIG. 2 is a cross-sectional view of the frame and motor unit of the same electric bicycle. FIG. 3 is a cross-sectional view cut along a plane passing through the axes of the input shaft of the motor unit, the rotation shaft of the motor, and the transmission rotation shaft of the reduction mechanism. FIG. 4 is an enlarged perspective view of a part of the output gear of the same motor unit. FIG. 5 is a cross-sectional view taken along a plane passing through the axes of the input shaft of the motor unit, the rotation shaft of the motor, and the transmission rotation shaft of the speed reduction mechanism according to the second embodiment.

The present disclosure relates to a motor unit and a two-wheeled vehicle, and more particularly to an electric bicycle such as a case, a motor, an output body, a motor unit having an output gear, an electrically assisted bicycle equipped with the motor unit, and an electric motorcycle.

Hereinafter, the first embodiment of the motor unit and the electric bicycle of the present disclosure will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, the electric bicycle 1 includes a frame 10, wheels 11, and a motor unit 3. The direction of travel of the electric bicycle 1 is determined by design. In the following description, the direction of travel is forward and the opposite direction is backward. In addition, the left and right sides shall be the left and right sides when facing forward.

The frame 10 supports a person who drives the electric bicycle 1 (hereinafter referred to as a driver). The load of the frame 10 and the driver is supported on the ground via the front wheels 111 and the rear wheels 112 that form the wheels 11.

The frame 10 has a head pipe 101, an upper pipe 102, a lower pipe 103, a standing 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-metal as a part. Further, the entire frame 10 may be formed of non-metal, and the material of the frame 10 is not particularly limited.

As shown in FIG. 2, the head pipe 101 is a tubular member that opens substantially in the vertical direction. The term "vertical direction" as used herein means a direction forming 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 vertically. The handle post 12 is rotatably inserted into the head pipe 101 in the axial direction. A front fork 121 is formed at the lower end of the handle post 12. The front wheel 111 is rotatably attached to the front fork 121. A handlebar 122 is fixed to the upper end of the handlepost 12. The handlebar 122 is provided with a hand operation unit for turning on / off the electric power, and a speed change operation unit for changing the speed by the speed change mechanism of the rear wheel 112.

As shown in FIG. 2, the upper pipe 102 is a tubular member extending substantially rearward from the head pipe 101. The upper pipe 102 does not necessarily have to be straight. It should be noted that the term "rear" as used herein means a direction forming an angle of about 40 degrees or less with the rear. The front end portion 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 vertical pipe 104.

The vertical pipe 104 is a tubular member that opens substantially in the vertical direction. The rear end portion of the upper pipe 102 is fixed to the side wall on the front side near the upper end portion of the vertical pipe 104 by welding or the like. As shown in FIG. 1, a shaft extending below the saddle 13 is inserted into the opening at the upper end of the vertical pipe 104. By fixing this shaft to the vertical pipe 104, the saddle 13 is fixed to the vertical pipe 104. The bracket 2 is fixed to the lower end of the vertical pipe 104.

As shown in FIG. 2, the lower pipe 103 is a tubular member that extends diagonally downward and substantially rearward of the head pipe 101. The upper pipe 102 does not necessarily have to be straight. It should be noted that the term "diagonally downward in the rear" as used herein means a direction in which the head pipe 101 is tilted downward from the extending direction and is lower than the rear. The front end portion of the lower pipe 103 is fixed to a portion of the side wall on the rear side of the head pipe 101 below the portion to which the upper pipe 102 is fixed by welding or the like. The bracket 2 is fixed to the rear end of the lower pipe 103. The bracket 2 is a part of the frame 10 and supports the motor unit 3.

The motor unit 3 is fixed to the lower side of the bracket 2, and the motor unit 3 is supported by the bracket 2. A wiring space 20 is formed between the inner surface of the bracket 2 and the outer surface of the motor unit 3.

The rear end of the lower 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 penetrating vertically is formed at the front end portion of the bracket 2, and the tubular portion 251 protrudes from a portion around the through hole 25. The rear end portion of the lower pipe 103 is covered and fitted to the tubular portion 251.

The lower end of the vertical pipe 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 penetrating vertically is formed in the middle portion of the bracket 2, and the tubular portion 261 projects from a portion around the through hole 26. The lower end portion of the vertical pipe 104 is covered and fitted to the tubular portion 261.

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 substantially rearward from the bracket 2. In the first embodiment, the front end portion of the tubular chain stay 106 is fixed to the rear end portion of the bracket 2 by welding. Further, a through hole 27 penetrating vertically is formed at a position corresponding to the internal space of the chain stay 106 of the bracket 2.

As shown in FIG. 1, the front end portion of the seat stay 105 is fixed to the rear end portion of the upper pipe 102 by fitting (including shrink fitting), fastening, welding, or the like. The seat stay 105 is two hollow or solid members extending substantially rearward from the vicinity of the upper end portion of the vertical pipe 104. In the first embodiment, the front end portion of the tubular seat stay 105 is fixed by welding or the like. The rear end portion of the seat stay 105 is fixed to the rear end portion of the chain stay 106, and the rear wheel 112 is rotatably attached to this portion.

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

The upper support portion 162 has a lock device to which the upper end portion of the battery 15 is attached and locks the battery 15 so that the battery 15 does not fall off.

Further, a shift wire 17 and a brake wire connecting the shift operation unit and the shift mechanism are passed through the lower pipe 103 and the wiring space 20.

Hereinafter, the motor unit 3 will be described with reference to FIG. 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 speed reduction mechanism 31.

Case 4 constitutes the outer shell of the motor unit 3. In the case 4, equipment such as a speed reduction mechanism 31 is housed in a storage space formed inside. The case 4 is mainly formed of a metal such as aluminum or stainless steel, but a non-metal may be used, and the material of the case 4 is not particularly limited.

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 case 4 is formed by combining the first divided body 41 and the second divided body 42. Case 4 will be described in more detail later.

In the first partition 41, the internal accommodation space is opened to the right. Further, the first partition body 41 has a motor cup 57. The motor cup 57 projects to one side in the lateral direction and houses the motor 5 inside. The motor cup 57 is attached to a part of the first partition body 41. The motor cup 57 is fixed to the first partition body 41 by a fastening member 571 made of bolts.

The internal accommodation space of the second divided body 42 is opened 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 accommodation spaces are continuous, and are fixed to each other by a fastening member made of bolts. The first divided body 41 and the second divided body 42 are fixed to each other to form the case 4. The size, shape, thickness, etc. of the case 4 are not particularly limited. Further, the accommodation space formed inside the case 4 may or may not be sealed.

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

The input shaft 6 is rotatably arranged around the axis 600 of the input shaft 6 through the case 4 in the axis 600 direction (left-right direction in the first embodiment). The input shaft 6 has an input shaft body 60 and an input body 7. The input shaft body 60 is composed of a solid member in the first embodiment, but may be composed of a hollow member.

The case 4 has a first bearing 45 that rotatably supports the input shaft body 60 on one end side (left end side in the first embodiment) in the axis 600 direction. 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 arranged in the input shaft hole 411. In the first embodiment, the first bearing 45 is composed of ball bearings. As the first bearing 45, various other bearings such as roller bearings can also be used, and the first bearing 45 is not limited to ball bearings.

Further, the case 4 has a second bearing 46 that rotatably supports the output body 8 on the other end side (right end side in the first embodiment) in the axis 600 direction. An input shaft hole 421 through which the input shaft body 60 passes is formed in the second divided body 42, and a second bearing 46 is arranged in the 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 composed of ball bearings. As the second bearing 46, various other bearings such as roller bearings can also be used, and the second bearing 46 is not limited to ball bearings.

As shown in FIG. 1, one end side of the crank arm 18 is fixed to the end of the input shaft body 60. A pedal 181 is rotatably attached to the other end side of the crank arm 18. The driver of the electric bicycle 1 can transmit the rotational force of human power to the input shaft body 60 by pedaling the pedal 181.

As shown in FIG. 3, the input body 7 is arranged along the outer peripheral surface of the input shaft body 60 and rotates integrally with the input shaft body 60. The input body 7 is a tubular member, the axis 600 of which faces the left-right direction, and is arranged 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 and 61 that are fitted to each other so as to be relatively non-rotatable around the axis 600 in a part of the axis 600 direction. In the first embodiment, 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 are fitted with

fitting portions

711 and 61 including a spline portion or a serration portion. Is formed. The

fitting portions

711 and 61 may be configured to be fitted by male and female threads.

Further, 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 in a part of the input shaft body 60 in the left-right direction, and is housed in the first division body 41. A fitting portion 711 that fits with the input shaft body 60 is formed at the left end portion of the first input body 71. A gap 70 is formed between the first input body 71 and the input shaft body 60 in the portion to the right of the fitting portion 711 at the left end. This makes it easier to insert the input shaft body 60 into the tubular first input body 71.

The second input body 72 is located at a position different from that of the first input body 71 in the axis 600 direction (to the right of the first input body 71 in the first embodiment), is connected to the first input body 71, and is connected to the output body 8. The rotational force is transmitted to. However, the second input body 72 may be partially located at the same position as the first input body 71 in the left-right direction. In the first embodiment, the left end portion of the second input body 72 is located outside the right end portion of the first input body 71 in the radial direction and overlaps in the radial direction. The first input body 71 and the second input body 72 have fitting portions 712 and 721 that are fitted to each other so as to be relatively non-rotatable around the axis 600. In the first embodiment, fitting portions 712 and 721 including spline portions, serration portions and the like are formed at the right end portion of the first input body 71 and the left end portion of the second input body 72. In the present disclosure, "overlapping in the radial direction" means a state in which at least a part of each object is viewed and overlapped in the radial direction.

The output body 8 is rotatably arranged around the axis 600 along the outer peripheral 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 member having a substantially tubular shape, the axis 600 of which faces the left-right direction, and is arranged concentrically with the input shaft body 60. The length of the output body 8 in the left-right direction is shorter than the length of the input shaft body 60 in the left-right direction. The right end portion of the output body 8 projects to the outside of the case 4 through the input shaft hole 421 formed in the second divided body 42. The output body 8 is supported by a second bearing 46 arranged in the second split body 42. The output body 8 constitutes the rotary shaft unit 30 together with the input shaft body 60 and the input body 7. The rotary shaft unit 30 is supported by the case 4 via the first bearing 45 and the second bearing 46.

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

As shown in FIG. 3, in the first embodiment, the one-way clutch 32 is arranged between the input body 7 and the output body 8. When the input body 7 is subjected to a rotational force in the direction of accelerating the electric bicycle 1 in the traveling direction (hereinafter referred to as the acceleration direction), the one-way clutch 32 transmits this rotational force to the output body 8 and is opposite to the acceleration direction. When a rotational force in the direction is applied, this rotational force is not transmitted to the output body 8. Further, the one-way clutch 32 does not transmit this rotational force to the input body 7 when a rotational force in the acceleration direction is applied to the output body 8 via the reduction mechanism 31 described later. In the first embodiment, the one-way clutch 32 has a ratchet and grease is supplied. As the one-way clutch 32, various ones 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.

Further, in the first embodiment, the second input body 72 and the output body 8 overlap in a part range in the axis 600 direction. A one-way clutch 32 is provided between the overlapping second input body 72 and the output body 8.

The second bearing 46 overlaps the one-way clutch 32 and the input shaft body 60 in the radial direction in a part of the axis 600 direction. In the first embodiment, the second bearing 46 is located outside the one-way clutch 32.

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 the reduction mechanism 31, and the rotational force is transmitted to the output body 8. The output gear 9 has a tooth portion 91 of the reduction mechanism 31 on the outer peripheral surface. The output gear 9 will be described later.

The deceleration mechanism 31 is housed in the case 4, decelerates the 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 a steel material.

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 formed of a tubular member, and a tooth portion 313 that meshes with a tooth portion 54 formed on the rotating shaft 51 of the motor 5 is formed on the outer peripheral surface thereof. The first transmission gear 311 is arranged along the outer peripheral surface of the transmission rotation shaft 310 included in 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 between the first transmission gear 311. The transmission rotation shaft 310 is formed of a metal such as a steel material.

The transmission rotation shaft 310 is rotatably housed in the case 4 so that the axis direction faces the left-right direction. The transmission rotation shaft 310 is located behind the rotation shaft 51 of the motor 5, and is arranged at substantially the same position as the portion of the rotation shaft 51 protruding to the right from the stator 53 in the left-right direction. The transmission rotation shaft 310 may be located in front of the rotation shaft 51 of the motor 5. The right end of the transmission rotary shaft 310 is supported by the transmission rotary shaft support bearing 3141 arranged in the second split body 42. The left end of the transmission rotary shaft 310 is supported by the transmission rotary shaft support bearing 3142 arranged in the first partition 41.

The first transmission gear 311 is connected to the transmission rotation shaft 310 via the one-way clutch 315. The one-way clutch 315 transmits this rotational force to the transmission rotary shaft 310 when a rotational force is applied to the first transmission gear 311 in the acceleration direction, and applies this rotational force when a rotational force is applied in the direction opposite to the acceleration direction. Transmission Do not transmit to the rotary shaft 310. Further, when a rotational force in the acceleration direction is applied to the transmission rotary shaft 310, this rotational force is not transmitted to the first transmission gear 311.

The second transmission gear 312 is fixed to the right side of the portion where the one-way clutch 315 of the transmission rotation shaft 310 is fixed so as to rotate integrally with the transmission rotation shaft 310. The second transmission gear 312 meshes with the tooth portion 91 of the output gear 9 and transmits the rotational force received from the first transmission gear 311 via the transmission rotation shaft 310 to the tooth portion 91 of the output gear 9. The second transmission gear 312 has a tooth portion 316 on the outer peripheral surface that meshes with the tooth portion 91 of the output gear 9.

When the driver pedals the pedal 181 of the electric bicycle 1, the input shaft body 60 is subjected to a rotational force in the acceleration direction. 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. As for the rotational force in the acceleration direction of the second input body 72, the rotational force in the acceleration direction 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. As a result, the electric bicycle 1 advances in the traveling direction.

Further, while the electric bicycle 1 is manually moving in the traveling direction, the rotational force from the motor 5 can be applied 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 that meshes with the rotating shaft 51 of the motor 5 rotates in the acceleration direction. The rotational force in the acceleration direction of the first transmission gear 311 is transmitted to the transmission rotation shaft 310 and the second transmission gear 312 fixed to the transmission rotation shaft 310 via the one-way clutch 315, and the second transmission gear 312 moves in the acceleration direction. Rotate. The rotational force in the acceleration direction of the second transmission gear 312 is transmitted to the output gear 9 that meshes with the second transmission gear 312. That is, the output body 8 functions as a resultant force body in which the rotational force of human power from the input body 7 and the rotational force from the motor 5 are combined. The motor unit 3 in the first embodiment is a so-called uniaxial motor unit 3.

Further, a case where the motor 5 is not driven while the electric bicycle 1 is manually moving in the traveling direction will be described. 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 that mesh 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 , The one-way clutch 315 does not transmit to the first transmission gear 311. As a result, the rotation shaft 51 and the rotor 52 are prevented from rotating when the motor 5 is not driven.

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 number of rotations of the input shaft body 60 per unit time. The torque applied to the input shaft body 60 is detected by the torque detection unit 33. The torque detection unit 33 is arranged in a part of the range in the axis 600 direction along the outer peripheral surface of the rotary shaft unit 30.

In the first embodiment, a magnetostrictive generating portion 331 to which magnetic anisotropy is imparted is formed on the outer peripheral surface of the first input body 71. Further, the coils 332 are arranged at a slight distance from the portion of the outer peripheral surface of the first input body 71 where the magnetostrictive generating portion 331 is provided. The magnetostriction generating unit 331 and the coil 332 constitute a magnetostriction type torque sensor as the torque detecting unit 33. As such a magnetostrictive torque sensor, various types can be appropriately used. Further, the torque detection unit 33 is not limited to the magnetostrictive torque sensor.

The torque detection unit 33 is arranged on the left side of the first transmission gear 311 and the second transmission gear 312, the one-way clutch 32, and the second bearing 46 in the axis 600 direction.

The rotation speed of the input shaft body 60 per unit time is detected by the rotation detection unit 34. The rotation detection unit 34 is arranged in a part of the range in the axis 600 direction along the outer peripheral surface of the rotation shaft unit 30.

In the first embodiment, on the outer peripheral surface side of the input body 7, on the right side of the coil 332 of the torque detection unit 33, there are light-transmitting portions formed between the tooth portions at regular intervals in the circumferential direction. The rotating body 341 is fixed so as to rotate integrally with the input body 7. Further, the optical sensor 342 is arranged so as to sandwich the tooth portion of the rotating body 341 from the left and right. The optical sensor 342 has a light emitting portion arranged on the left side of the tooth portion and a light receiving portion arranged on the right side of the tooth portion, 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 rotating body 341 and an optical sensor 342, various ones can be appropriately used. Further, the rotation detection unit 34 is not limited to the one having the rotating body 341 and the optical sensor 342.

The rotation detection unit 34 is located at the same position as the first transmission gear 311 in the axis 600 direction, and is arranged on the left side of the second transmission gear 312, the one-way clutch 32, and the second bearing 46. In the present disclosure, "located at the same position in the axis 600 direction" means a state in which at least a part of the axis overlaps in the direction orthogonal to the axis 600 direction.

In the motor unit 3, a control board 35 having a control unit for controlling the motor 5 is arranged in the case 4. 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 such control units can be appropriately used, and detailed description thereof 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 rotation speed detected by the rotation detection unit 34.

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 spline coupling or the like, but are not particularly limited. At least the tooth portions 91 of the output gear 9 are made of resin. In the first embodiment, the entire output gear 9 is made of resin. On the other hand, the second transmission gear 312 and the transmission rotation shaft 310 that mesh with the tooth portion 91 are made of metal.

Since the tooth portion 91 of the output gear 9 is formed of resin, even if the mating partner (second transmission gear 312 in the first embodiment) that meshes with the tooth portion 91 is metal, collision between the metals does not occur. The toothing noise due to the meshing of the tooth portions 91 of the output gear 9 is unlikely to occur. This makes it easy to configure the quiet motor unit 3.

Further, in the first embodiment, when the rotation 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, there is no gear 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. Therefore, the rattling noise that is likely to occur when the gears are interposed is not generated, and it is easier to configure the quiet motor unit 3.

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

Further, in the first embodiment, the position of the second bearing 46 and the position of the tooth portion 91 of the output gear 9 partially overlap in the radial direction of the output body 8. By overlapping the position of the second bearing 46 and the position of the tooth portion 91 in the axis 600 direction in this way, the length of the motor unit 3 in the axis 600 direction can be easily shortened.

Further, in the first embodiment, as shown in FIG. 4, the output gear 9 is a helical gear whose tooth portion 91 is a tooth. As a result, the meshing ratio in the tooth portion 91 is improved, and it is easier to form the quiet motor unit 3. The tooth portion 91 may be a flat tooth.

Further, in the first embodiment, the outer diameter D of the output gear 9 (twice the length from the rotation center axis of the output gear 9 to the tip of the tooth portion 91) is 125 mm or less. As a result, the motor unit 3 and the two-wheeled vehicle (electric bicycle 1) can be miniaturized. In particular, the distance between the so-called rear center from the center of the rear wheel 112 to the axis 600 of the input shaft body 60 can be shortened, which facilitates the handling of the two-wheeled vehicle (electric bicycle 1).

Further, it is more preferable that the outer diameter D of the output gear 9 is 98 mm or less. As a result, the motor unit 3 and the two-wheeled vehicle (electric bicycle 1) can be further miniaturized, and the handling of the two-wheeled vehicle (electric bicycle 1) becomes easier.

Further, 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 more compact. Further, by making the tooth portion 91 a tooth with a torsion angle θ (angle formed by the longitudinal direction of the tooth with respect to the width W direction) of 25 ° or less, or a spur tooth, the posture stability of the output gear 9 is stable. Can be improved. Further, if the width of the tooth portion 91 in the W direction (corresponding to the axis line 600 direction) is 10 mm or more and 35 mm or less, the motor unit 3 can be made more compact. At this time, the output torque of the output body 8 is preferably 20 Nm or more and less than 50 Nm.

Further, 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. Further, by setting the torsion angle θ (angle formed by the longitudinal direction of the tooth portion with respect to the width W direction) of the tooth portion 91 to 10 ° or more and 25 ° or less, the durability of the tooth portion 91 is improved. It can be made quiet. Further, if the width of the tooth portion 91 in the W direction (corresponding to the axis line 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. At this time, the output torque of the output body 8 is preferably 50 Nm or more.

Further, in the first embodiment, as shown in FIG. 3, the length 521 of the rotor 52 in the axial direction (same as the axial direction 600) is shorter than the length 531 of the stator 53 in the axial direction. As a result, the length of the magnet of the rotor 52 in the axial direction can be easily shortened, and the cost can be easily suppressed.

Further, 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.

Next, the motor unit 3 of the second embodiment will be described with reference to FIG. The motor unit 3 of the second embodiment is almost the same as the motor unit 3 of the first embodiment. Hereinafter, the parts different from the second embodiment will be mainly described.

In the first embodiment shown in FIG. 3, the one-way clutch 32 is arranged between the input body 7 and the output body 8. On the other hand, in the second embodiment, the one-way clutch 32 is not arranged, and the input body 7 and the output body 8 have a connecting portion for connecting the input body 7 and the output body 8 so as to rotate integrally. It differs in that it has.

A spline portion 73 composed of irregularities arranged side by side in the circumferential direction is formed on the outer peripheral surface of the input body 7. Similarly, on the inner peripheral surface of the output body 8, a spline portion 82 which is juxtaposed in the circumferential direction and has irregularities that mesh with the spline portion 73 is formed. The spline portion 73 and the spline portion 82 form a connecting portion.

By forming such a connecting portion on the input body 7 and the output body 8, the input body 7 and the output body 8 can be easily rotated integrally. In particular, when a so-called coaster brake is adopted, such a connecting portion functions effectively.

The connecting portion is not limited to the spline portion 73 and the spline portion 82, and for example, even if a key groove is formed on the outer surfaces of the input body 7 and the output body 8 and the key is fitted into the key groove. Good.

Next, a modified example of the first embodiment and the second embodiment will be described.

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.

The output gear 9 may be a spur gear instead of a screw tooth gear.

The outer diameter D, width W, and torsion angle of the output gear 9 in the case of a helical tooth gear are not particularly limited.

In the first embodiment and the second embodiment, the entire output gear 9 was made of resin. On the other hand, only the tooth portion 91 may be formed of resin. The output gear 9 has a base portion and a tooth portion 91 attached to the outer peripheral surface of the base portion. The base contains more than 50% of metals other than aluminum. The metal other than aluminum is preferably iron or SUS, but is not particularly limited. Further, the base may be a sintered alloy of a metal containing more than 50% of a metal other than aluminum such as iron and SUS.

Since aluminum has a large thermal expansion, it is possible to suppress the thermal expansion by using a metal other than aluminum such as iron and SUS. Further, since metals such as iron and SUS have a higher strength per volume than aluminum, it is easy to make the motor unit 3 compact with the same strength.

As is clear from the first embodiment and the second embodiment described above and their modifications, the motor unit (3) of the first aspect includes the case (4), the motor (5), and the output body ( 8), an input shaft (6), and an output gear (9) are provided. The motor (5) is housed in the case (4). The output body (8) is rotatably arranged around the axis through the case (4) in the axial direction (same as the axis (600) direction). The input shaft (6) is rotatably arranged around the axis (600) through the case (4) in the axis (600) direction. The output gear (9) is attached to the output body (8), receives the rotational force of the motor (5), and transmits the rotational force to the output body (8). At least the teeth (91) of the output gear (9) are made of resin.

According to the first aspect, since the tooth portion (91) of the output gear (9) is formed of resin, even if the mating partner with the tooth portion (91) is a metal, collision between the metals can occur. However, the tooth striking noise due to the 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).

The motor unit (3) of the second aspect can be realized in combination with the first aspect. In the second aspect, the motor unit (3) further comprises a transmission rotation shaft (310). The transmission rotation shaft (310) transmits a rotational force to the first transmission gear (311) that meshes with the rotation shaft (51) of the motor (5) and rotates, and meshes with the output gear (9) to transmit the rotational force to the output gear (9). It has a second transmission gear (312).

According to the second aspect, the so-called two-stage deceleration is transmitted to the output body (8), so that a large deceleration can be easily achieved.

The motor unit (3) of the third aspect can be realized by combining with 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) match.

According to the third aspect, the rattling noise that is likely to occur when a gear is intervened is not generated, and it is easier to configure a quiet motor unit (3).

The motor unit (3) of the fourth aspect can be realized in combination with the third aspect. In a fourth aspect, the case (4) has a bearing (second bearing (46)) that rotatably supports the rotary 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).

According to the fourth aspect, the axis (600) of the motor unit (3) is formed 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 in the direction.

The motor unit (3) of the fifth aspect can be realized by combining with any one of the first to fourth aspects. In a fifth aspect, the output gear (9) has a base and teeth (91) attached to the outer peripheral surface of the base. The base contains more than 50% of metals other than aluminum.

According to the fifth aspect, it is easy to suppress the thermal expansion of the output gear (9), and it is easy to make the motor unit (3) compact.

The motor unit (3) of the sixth aspect can be realized by combining with any one of the first to fifth aspects. In the sixth aspect, the outer diameter of the output gear (9) is 125 mm or less.

According to the sixth aspect, the size of the motor unit (3) can be reduced.

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 tooth.

According to the seventh aspect, the meshing rate at the tooth portion (91) is improved, and it is easier to form a quiet motor unit (3).

The motor unit (3) of the eighth aspect can be realized by combining with any one of the first to seventh aspects. In the eighth aspect, the outer diameter of the output gear (9) is 98 mm or less.

According to the eighth aspect, the size of the motor unit (3) can be reduced.

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 any one of the first to eighth motor units (3).

According to the ninth aspect, it is easy to make an electric bicycle (1) equipped with a quiet motor unit (3).

1 Electric bicycle 3 Motor unit 30 Rotating shaft unit 310 Transmission rotating shaft 311 1st transmission gear 312 2nd transmission gear 4 Case 46 2nd bearing 5 Motor 51 Rotating shaft 6 Input shaft 600 Axis 8 Output body 9 Output gear 91 Tooth

Claims

With the case
The motor housed in the case and
An output body that is rotatably arranged around the axis through the case in the axial direction,
An input shaft that is rotatably arranged around the axis through the case in the axial direction,
An output gear that is attached to the output body and receives the rotational force of the motor and transmits the rotational force to the output body.
With
The output gear is a motor unit whose teeth are made of resin at least.
Further equipped with a transmission rotation axis,
The first transmission gear, wherein the transmission rotation shaft includes a first transmission gear that meshes with the rotation shaft of the motor and rotates, and a second transmission gear that meshes with the output gear and transmits a rotational force to the output gear. Motor unit.
The motor unit according to claim 1 or 2, wherein the rotation speed of the input shaft and the rotation speed of the output body match.
The case has bearings that rotatably support a rotary shaft unit that includes the input shaft.
The motor unit according to claim 3, wherein the position of the bearing and the position of the output gear overlap in the radial direction of the output body.
The output gear has a base and the tooth portion attached to the outer peripheral surface of the base.
The motor unit according to any one of claims 1 to 4, wherein the base portion contains more than 50% of a metal other than aluminum.
The motor unit according to any one of claims 1 to 5, wherein the outer diameter of the output gear is 125 mm or less.
The motor unit according to any one of claims 1 to 6, wherein the tooth portion is a tooth.
The motor unit according to any one of claims 1 to 7, wherein the outer diameter of the output gear is 98 mm or less.
An electric bicycle comprising the motor unit according to any one of claims 1 to 8.