JP7325016B2 - Motor unit and electric bicycle - Google Patents

Description

The present disclosure relates to motor units and electric bicycles.

2. Description of the Related Art Conventionally, an electrically assisted bicycle equipped with a motor drive unit is known (see, for example, Patent Literature 1). A motor drive unit disclosed in Patent Document 1 includes a unit case, a motor, an interlocking member fitted to a sprocket, and a reduction gear. A small-diameter reduction gear portion attached to a small-diameter support shaft portion of a reduction gear of a reduction gear meshes with a large-diameter gear portion integrally formed with an interlocking body, so that the rotational torque of the motor is transferred to the large-diameter gear portion of the interlocking body. introduce.

WO2014/184826

Conventionally, in the above-described electrically power-assisted bicycle, both the small-diameter reduction gear portion of the reduction gear and the large-diameter gear portion of the interlocking body are usually made of metal. For this reason, there is a problem that the small-diameter gear portion for speed reduction and the large-diameter gear portion are likely to mesh with each other, resulting in rattling noise.

In view of the conventional problems described above, an object of the present disclosure is to provide a motor unit and an electric bicycle in which rattling noise is less likely to occur due to meshing of an output gear.

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

In order to solve the above problems, one form of an electric bicycle includes the motor unit.

In the motor unit and the electric bicycle according to the aspect of the present disclosure, gear rattle noise is less likely to occur due to meshing of the output gear.

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 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 motor unit. FIG. 5 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 speed reduction mechanism according to the second embodiment.

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

A first embodiment of a motor unit and an electric bicycle according to the present disclosure will be described below with reference to FIGS. 1 to 4. FIG.

As shown in FIG. 1 , the electric bicycle 1 includes a frame 10 , wheels 11 and a motor unit 3 . It should be noted that the traveling direction of the electric bicycle 1 is determined in terms of design. In the following description, the forward direction is the forward direction and the rearward direction is the opposite direction. In addition, the left and right directions refer to the left and right directions 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 rear wheels 112 that constitute 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 metal such as aluminum or stainless steel, but may partially contain non-metal. Also, the entire frame 10 may be made 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 cylindrical member that opens generally vertically. It should be noted that the generally vertical direction here 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 through the head pipe 101 vertically. The handle post 12 is axially rotatably inserted into the head pipe 101 . 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 handle bar 122 is fixed to the upper end of the handle post 12 . The handlebar 122 is provided with a hand operation portion for turning on/off the electric power, and a speed change operation portion 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 generally rearward from the head pipe 101 . The upper pipe 102 does not necessarily have to be straight. In addition, the term "substantially rearward" as used herein means a direction forming an angle of about 40 degrees or less with respect to the rearward direction. A front end portion of the upper pipe 102 is fixed to a rear side wall of the head pipe 101 by welding or the like. A rear end portion of the upper pipe 102 is fixed to the standing pipe 104 .

The standing pipe 104 is a cylindrical member that opens generally vertically. The rear end of the upper pipe 102 is fixed to the front side wall near the upper end of the vertical 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 standing pipe 104, as shown in FIG. By fixing this shaft to the standing pipe 104 , the saddle 13 is fixed to the standing pipe 104 . A bracket 2 is fixed to the lower end of the standing pipe 104 .

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

A 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 portion of the lower pipe 103 is fixed to the front end portion of the bracket 2 by fitting (including shrink fitting), fastening, welding, or the like. In the first embodiment, a through hole 25 is formed vertically through the front end portion of the bracket 2 , and a cylindrical portion 251 protrudes from a portion around the through hole 25 . The rear end portion of the lower pipe 103 is put on and fitted to the cylindrical portion 251 .

A lower end portion of the standing pipe 104 is fixed to an 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 is formed vertically through the intermediate portion of the bracket 2 , and a tubular portion 261 protrudes from a portion around the through-hole 26 . The lower end of the vertical pipe 104 is put on 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. Chainstays 106 are two hollow or solid members extending generally rearward from bracket 2 . In the first embodiment, the front end portion of a tubular chain stay 106 is fixed to the rear end portion of the bracket 2 by welding. Also, a through hole 27 is formed vertically through the bracket 2 at a position corresponding to the internal space of the chain stay 106 .

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 stays 105 are two hollow or solid members extending substantially rearward from the vicinity of the upper end of the standing pipe 104 . In the first embodiment, the front end portion of the tubular seat stay 105 is fixed by welding or the like. A rear end portion of the seat stay 105 is fixed to a rear end portion of the chain stay 106, and a 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 to 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 part 161 supports the battery 15 so that the lower end of the battery 15 is not easily dropped. In addition, the lower support portion 161 has a plurality of terminals electrically connected to a plurality of battery terminals for power supply or signal formed at the lower end of the battery 15 . One end of the wiring 163 is electrically connected to each of the terminals.

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

In the lower pipe 103 and the wiring space 20, a shift wire 17 and a brake wire that connect the shift operation section and the shift mechanism are passed.

The motor unit 3 will be described below with reference to FIG. The motor unit 3 includes a case 4 , a motor 5 , an output member 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. As shown in FIG.

Case 4 forms an outer shell of motor unit 3 . The case 4 accommodates devices such as the speed reduction mechanism 31 in an accommodation space formed therein. The case 4 is mainly made of metal such as aluminum or stainless steel, but non-metal may be used, and the material of the case 4 is not particularly limited.

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

In the first divided body 41, the internal accommodation space is open to the right. The first divided body 41 also has a motor cup 57 . The motor cup 57 protrudes to one side in the short direction and accommodates the motor 5 therein. A motor cup 57 is attached to a portion of the first split body 41 . The motor cup 57 is fixed to the first divided body 41 by a fastening member 571 made of a bolt.

The second divided body 42 has an internal accommodation space 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 accommodation spaces are continuous, and are fixed to each other by fastening members made of bolts. The first divided body 41 and the second divided body 42 are fixed to each other to form the case 4 . Note that the size, shape, thickness, and the like of the case 4 are not particularly limited. Moreover, the accommodation space formed inside the case 4 may or may not be sealed.

A motor 5 is attached to the case 4 . More specifically, the motor 5 is housed within a motor cup 57 attached mainly to the first split body 41 . The motor 5 is housed inside the case 4 . The motor 5 has a rotating shaft 51 , a rotor 52 rotating integrally with the rotating shaft 51 , and a stator 53 . Rotor 52 , stator 53 and a portion of rotating shaft 51 are located within motor cup 57 . The rotating shaft 51 is rotatably accommodated so that the axial direction thereof faces the left-right direction. The rotating shaft 51 protrudes to one side (to the right in the first embodiment) from the stator 53 , and a toothed portion 54 that meshes with the speed reduction mechanism 31 is formed on the outer surface of the protruding portion. A right end portion 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 protrude from the stator 53 and is supported by a rotating shaft support bearing 552 arranged in the motor cup 57 .

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

The case 4 has a first bearing 45 that rotatably supports the input shaft 60 on one end side (the left end side in the first embodiment) in the direction of the axis 600 . 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 1st embodiment, the 1st bearing 45 is comprised by a ball bearing. Various other bearings such as a roller bearing can be used as the first bearing 45, and the first bearing 45 is not limited to a ball bearing.

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

One end of the crank arm 18 is fixed to the end of the input shaft 60, as shown in FIG. A pedal 181 is rotatably attached to the other end of the crank arm 18 . A rider of the electric bicycle 1 can transmit a human rotational force to the input shaft body 60 by pedaling the pedals 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 together with the input shaft body 60 . The input body 7 is a cylindrical member, the axis 600 of which faces the horizontal 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 unrotatable around the axis line 600 at a part in the direction of the axis line 600 . 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 formed of spline portions, serration portions, or the like. is formed. The fitting portions 711 and 61 may be configured to be fitted with a male screw and a female screw.

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 in a part of the input shaft body 60 in the left-right direction and is housed inside the first divided 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 at a 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 cylindrical first input body 71 .

The second input body 72 is located at a different position from the first input body 71 in the direction of the axis 600 (on the right side of the first input body 71 in the first embodiment) and connected to the first input body 71 . to transmit rotational force to However, the second input body 72 and the first input body 71 may be partially positioned at the same position in the horizontal direction. In the first embodiment, the left end portion of the second input member 72 is positioned radially outside the right end portion of the first input member 71, 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 together so as to be relatively unrotatable about the axis 600 . In the first embodiment, the right end of the first input body 71 and the left end of the second input body 72 are formed with fitting portions 712 and 721 made up of spline portions, serration portions, or the like. In the present disclosure, "overlapping in the radial direction" refers to a state in which at least a part of each target overlaps when viewed in the radial direction.

The output body 8 is rotatably arranged around the axis 600 along the outer peripheral surface of the input shaft 60 and penetrates the case in the direction of the axis 600 . The output body 8 receives rotational force from the input body 7 . The output body 8 is a substantially cylindrical member, and its axis 600 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. A right end portion of the output body 8 protrudes outside the case 4 through an input shaft hole 421 formed in the second split body 42 . The output body 8 is supported by a second bearing 46 arranged on the second split body 42 . The output body 8 constitutes the rotating shaft unit 30 together with the input shaft body 60 and the input body 7 . The rotating shaft unit 30 is supported by the case 4 via the first bearing 45 and the second bearing 46 .

A front sprocket 191 is fixed by a lock ring 195 to the portion of the output member 8 protruding outside the case 4 . The front sprocket 191 rotates integrally with the output body 8 . Also, 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 .

As shown in FIG. 3, a one-way clutch 32 is arranged between the input body 7 and the output body 8 in the first embodiment. The one-way clutch 32 transmits the rotational force to the output body 8 when a rotational force is applied to the input body 7 in a direction that accelerates the electric bicycle 1 in the direction of travel (hereinafter referred to as the acceleration direction). When a directional rotational force is applied, this rotational force is not transmitted to the output body 8 . Further, the one-way clutch 32 does not transmit the rotational force to the input body 7 when the rotational force in the acceleration direction is applied to the output body 8 via the speed reduction mechanism 31 to be described later. In the first embodiment, the one-way clutch 32 has a ratchet and is greased. Various types of one-way clutch 32 can be used as appropriate, and are not limited. For example, a roller type one-way clutch or a sprag type one-way clutch may be used.

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 . A one-way clutch 32 is provided between the overlapping second input member 72 and output member 8 .

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

An output gear 9 is attached to the output body 8 . The output gear 9 rotates integrally with the output body 8 as a part of 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 rotational force of the motor 5 is received by the output gear 9 via the speed reduction mechanism 31 and transmitted to the output body 8 . The output gear 9 has teeth 91 of the speed reduction mechanism 31 on its outer peripheral surface. The output gear 9 will be described later.

The speed reduction mechanism 31 is housed in the case 4 to reduce the speed of rotation of the motor 5 and transmit it to the output body 8 . The speed reduction mechanism 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 greater than the number of teeth of the second transmission gear 312 . The second transmission gear 312 is made of metal such as steel.

The first transmission gear 311 meshes with the rotating shaft 51 of the motor 5 and rotates by the torque received from the rotating shaft 51 . In the first embodiment, the first transmission gear 311 is formed of a tubular member, and has a toothed portion 313 formed on the outer peripheral surface thereof to mesh with the toothed portion 54 formed on the rotating shaft 51 of the motor 5 . The first transmission gear 311 is arranged along the outer peripheral surface of the transmission rotation shaft 310 of the speed reduction mechanism 31 . In the first embodiment, the first transmission gear 311 receives the rotational force directly from the rotating shaft 51 of the motor 5, but a gear may be interposed therebetween. Transmission rotary shaft 310 is made of metal such as steel.

The transmission rotary shaft 310 is rotatably accommodated in the case 4 so that the axial direction thereof faces the left-right direction. The transmission rotary shaft 310 is positioned behind the rotary shaft 51 of the motor 5 and is arranged at substantially the same position as the portion of the rotary shaft 51 protruding rightward from the stator 53 in the left-right direction. Note that the transmission rotation shaft 310 may be positioned forward of the rotation shaft 51 of the motor 5 . A right end portion of the transmission rotary shaft 310 is supported by a transmission rotary shaft support bearing 3141 arranged in the second split body 42 . A left end portion of the transmission rotary shaft 310 is supported by a transmission rotary shaft support bearing 3142 arranged in the first split body 41 .

The first transmission gear 311 is connected to the transmission rotary shaft 310 via a one-way clutch 315 . The one-way clutch 315 transmits the rotational force to the transmission rotary shaft 310 when the first transmission gear 311 receives rotational force in the acceleration direction, and transfers the rotational force when the rotational force in the direction opposite to the acceleration direction is applied. It does not transmit to the transmission 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 .

A second transmission gear 312 is fixed to the right side of the portion of the transmission rotary shaft 310 to which the one-way clutch 315 is fixed so as to rotate integrally with the transmission rotary shaft 310 . The second transmission gear 312 meshes with the teeth 91 of the output gear 9 and transmits the torque received from the first transmission gear 311 via the transmission rotation shaft 310 to the teeth 91 of the output gear 9 . The second transmission gear 312 has teeth 316 on its outer peripheral surface that mesh with the teeth 91 of the output gear 9 .

When the rider pedals the pedals 181 of the electric bicycle 1, a rotational force is applied to the input shaft body 60 in the acceleration direction. When the input shaft body 60 rotates, the first input body 71 and the second input body 72 rotate together with the input shaft body 60 . The rotational force of the second input member 72 in the acceleration direction is applied to the output member 8 via the one-way clutch 32, and the output member 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 moves in the direction of travel.

Further, while the electric bicycle 1 is moving in the traveling direction by human power, the rotational force from the motor 5 can be applied to the output member 8 as an auxiliary force. A detailed description is given below. When the rotation shaft 51 of the motor 5 rotates in the acceleration direction, the first transmission gear 311 meshing with the rotation 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 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 is transmitted in the acceleration direction. Rotate. The rotational force of the second transmission gear 312 in the accelerating direction is transmitted to the output gear 9 meshing with the second transmission gear 312 . In other words, the output member 8 functions as a resultant force in which the human torque from the input member 7 and the torque from the motor 5 are combined. The motor unit 3 in the first embodiment is a so-called uniaxial motor unit 3 .

Also, a case will be described in which the motor 5 is not driven while the electric bicycle 1 is manually traveling in the direction of travel. 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. , is not transmitted to the first transmission gear 311 by the one-way clutch 315 . As a result, the rotating 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 60 and the number of rotations of the input shaft 60 per unit time. Torque applied to the input shaft 60 is detected by the torque detector 33 . The torque detector 33 is arranged in a partial range in the direction of the axis 600 along the outer peripheral surface of the rotating shaft unit 30 .

In the first embodiment, a magnetostriction generating portion 331 imparted with magnetic anisotropy is formed on the outer peripheral surface of the first input body 71 . A coil 332 is arranged with a slight gap from the portion of the outer peripheral surface of the first input member 71 where the magnetostriction generating portion 331 is provided. A magnetostrictive torque sensor as the torque detector 33 is configured by the magnetostrictive generator 331 and the coil 332 . Various magnetostrictive torque sensors can be used as appropriate. Moreover, the torque detection unit 33 is not limited to a magnetostrictive torque sensor.

The torque detector 33 is arranged on the left side 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. As shown in FIG.

The number of revolutions per unit time of the input shaft 60 is detected by the rotation detector 34 . The rotation detector 34 is arranged in a partial range in the direction of the axis 600 along the outer peripheral surface of the rotary shaft unit 30 .

In the first embodiment, on the outer peripheral surface side of the input body 7 and on the right side of the coil 332 of the torque detection unit 33, there are light transmitting portions formed between teeth at regular intervals in the circumferential direction. A rotating body 341 is fixed so as to rotate integrally with the input body 7 . Further, optical sensors 342 are arranged so as to sandwich the teeth 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 and a light receiving portion arranged on the right side of the tooth, but the positional relationship between the light emitting portion and the light receiving portion is not limited. As the rotation detector 34 having such a rotating body 341 and optical sensor 342, various devices can be used as appropriate. Also, the rotation detection unit 34 is not limited to having the rotating body 341 and the optical sensor 342 .

The rotation detector 34 is located at the same position as the first transmission gear 311 in the direction of the axis 600 and is arranged to the left 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 direction of the axis 600" refers to a state in which at least a portion overlaps when viewed in a direction perpendicular to the direction of the axis 600. FIG.

In the motor unit 3 , a control board 35 having a control section for controlling the motor 5 is arranged inside 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). A variety of such control units can be used as appropriate, and detailed description thereof will be omitted. The controller controls the torque from the motor 5 based on the torque detected by the torque detector 33 and the number of rotations detected by the rotation detector 34 .

The output gear 9 is attached with the output body 8 fitted therein. 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 the connection is not particularly limited. At least the tooth portion 91 of the output gear 9 is 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 rotary shaft 310 that mesh with the tooth portion 91 are made of metal.

Since the tooth portion 91 of the output gear 9 is made of resin, even if the counterpart (the second transmission gear 312 in the first embodiment) that meshes with the tooth portion 91 is metal, collision between metals does not occur. Rattling noise due to meshing of the tooth portion 91 of the output gear 9 is less likely to occur. This makes it easy to configure a quiet motor unit 3 .

Further, in the first embodiment, when the rotary 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 for transmitting the rotational force of the input shaft 6 to the output body 8 is interposed between the input shaft 6 and the output body 8 . Therefore, rattling noise that tends to occur when gears are interposed does not occur, and the motor unit 3 can be configured to be even quieter.

In addition, in the first embodiment, the rotational force of the motor 5 is transmitted to the output member 8 by so-called two-stage reduction via the first transmission gear 311 and the second transmission gear 312, so that large reduction is 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 direction of the axis 600 in this way, it is easy to shorten the length of the motor unit 3 in the direction of the axis 600 .

Further, in the first embodiment, as shown in FIG. 4, the output gear 9 is a helical gear whose tooth portion 91 is helical. As a result, the meshing ratio of the tooth portion 91 is improved, and the quieter motor unit 3 can be easily configured. Note that the tooth portion 91 may be a spur tooth.

Further, in the first embodiment, the outer diameter D of the output gear 9 (twice the length from the center axis of rotation of the output gear 9 to the tip of the tooth portion 91) is 125 mm or less. As a result, the size of the motor unit 3 and the two-wheeled vehicle (electric bicycle 1) can be reduced. 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).

Furthermore, 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 two-wheeled vehicle (electric bicycle 1) can be handled more easily.

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, the gear 91 can be stabilized in posture by making the tooth portion 91 a helical tooth having 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 a spur tooth. can be improved. Further, if the length of the tooth portion 91 in the width W direction (which coincides with the direction of the axis 600) is 10 mm or more and 35 mm or less, the motor unit 3 can be made more compact. In this case, the output torque of the output member 8 is preferably 20 Nm or more and less than 50 Nm.

Moreover, 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, the torsion angle θ of the helical teeth of the tooth portion 91 (the angle formed by the longitudinal direction of the helical tooth with respect to the width W direction) is set to 10° or more and 25° or less, thereby improving the durability of the tooth portion 91. It can be muted. Further, if the length of the tooth portion 91 in the width W direction (aligned with the direction of the axis 600) 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, the output torque of the output body 8 is preferably 50 Nm or more.

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

Also, 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 explained based on FIG. The motor unit 3 of the second embodiment is mostly the same as the motor unit 3 of the first embodiment. Hereinafter, mainly different parts from the second embodiment will be described.

In the first embodiment shown in FIG. 3, a one-way clutch 32 is arranged between the input member 7 and the output member 8. As shown in FIG. 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 are connected to each other so that the input body 7 and the output body 8 rotate integrally. different in that they have

A spline portion 73 is formed on the outer peripheral surface of the input body 7 and is formed of unevenness arranged in parallel in the circumferential direction. Similarly, on the inner peripheral surface of the output member 8 , a spline portion 82 is formed which is arranged in parallel in the circumferential direction and which is made up of protrusions and recesses that mesh with the spline portion 73 . A connecting portion is configured by the spline portion 73 and the spline portion 82 .

By forming such a connection part in the input body 7 and the output body 8, it becomes easy to rotate the input body 7 and the output body 8 integrally. Especially when a so-called coaster brake is employed, such a connecting portion functions effectively.

The connection portion is not limited to the spline portion 73 and the spline portion 82. For example, key grooves may be formed on the outer surfaces of the input body 7 and the output body 8, and a key may be fitted into the key groove. good.

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

The rotational force of the motor 5 may be transmitted to the output member 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 helical gear.

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

In the first embodiment and the second embodiment, 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 teeth 91 attached to the outer peripheral surface of the base. The base contains greater than 50% metal other than aluminum. Metals other than aluminum are preferably iron and SUS, but are not particularly limited. Also, the base may be a sintered metal alloy containing more than 50% of a metal other than aluminum, such as iron or SUS.

Since aluminum has a large thermal expansion, the thermal expansion can be suppressed by using a metal other than aluminum, such as iron or SUS. In addition, since metals such as iron and SUS have higher strength per volume than aluminum, the motor unit 3 can be easily made compact with the same strength.

As is clear from the first and second embodiments and their modifications described above, the motor unit 3 of the first aspect includes the case 4, the motor 5, the output member 8, and the input shaft 6. , an output gear 9 . The motor 5 is housed inside the case 4 . The output body 8 penetrates the case 4 in the axial direction (same as the direction of the axis 600) and is arranged rotatably around the axis. The input shaft 6 penetrates the case 4 in the direction of the axis 600 and is arranged rotatably around the axis 600 . 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 tooth portion 91 of the output gear 9 is made of resin.

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, the metals do not collide with each other. Tooth rattling noise due to meshing of the tooth portion 91 is less likely to occur. This makes it easy to configure a quiet motor unit 3 .

The motor unit 3 of the second aspect can be realized by combining with the first aspect. In a second aspect, the motor unit 3 further comprises a transmission rotary shaft 310. As shown in FIG. The transmission rotary shaft 310 has a first transmission gear 311 that meshes with the rotation shaft 51 of the motor 5 and rotates, and a second transmission gear 312 that meshes with the output gear 9 and transmits rotational force to the output gear 9 .

According to the second aspect, the transmission to the output member 8 is achieved by so-called two-stage speed reduction, so it is easy to achieve a large speed reduction.

The motor unit 3 of the third mode can be realized by combining with the first or second mode. In the third aspect, the rotational speed of the input shaft 6 and the rotational speed of the output member 8 are the same.

According to the third aspect, it is easy to configure a quieter motor unit 3 without generating rattling noise that tends to occur when gears are interposed.

The motor unit 3 of the fourth aspect can be realized by combining with the third aspect. In the fourth aspect, case 4 has a bearing (second bearing 46 ) that rotatably supports rotary shaft unit 30 including 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, by overlapping the position of the second bearing 46 and the position of the tooth portion 91 in the radial direction of the output member 8, the length of the motor unit 3 in the direction of the axis 600 can be easily shortened.

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 greater than 50% metal other than aluminum.

According to the fifth aspect, thermal expansion of the output gear 9 can be easily suppressed, and the size of the motor unit 3 can be easily reduced.

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 a seventh aspect, the teeth 91 are helical teeth.

According to the seventh aspect, the meshing ratio of the tooth portion 91 is improved, and the quieter motor unit 3 can be easily constructed.

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, the electric bicycle 1 equipped with the quiet motor unit 3 can be easily obtained.

1 electric bicycle 3 motor unit 30 rotary shaft unit 310 transmission rotary shaft 311 first transmission gear 312 second transmission gear 4 case 46 second bearing 5 motor 51 rotary shaft 6 input shaft 600 axis 8 output body 9 output gear 91 teeth

Claims (9)

a case;
a motor housed in the case;
an output body that passes through the case in the axial direction and is arranged to be rotatable about the axis;
an input shaft penetrating the case in the axial direction and arranged to be rotatable about the axis by human power ;
an output gear attached to the output body for receiving the rotational force of the motor and transmitting the rotational force of the motor to the output body;
with
the output body is rotated by receiving the rotational force of the input shaft and the rotational force of the motor;
The output gear has a tooth portion formed of resin ,
The motor unit , wherein the inner surface of the output gear attached to the outer surface of the output body is made of metal . further comprising a transmission rotary shaft,
2. The transmission rotary shaft according to claim 1, comprising: a first transmission gear that meshes with and rotates with the rotation shaft of the motor; and a second transmission gear that meshes with the output gear and transmits rotational force to the output gear. motor unit. The motor unit according to claim 1 or 2, wherein the number of rotations of the input shaft and the number of rotations of the output member are the same. the case has a bearing that rotatably supports a rotating shaft unit including the input shaft;
The motor unit according to claim 3, wherein the position of the bearing overlaps the position of the output gear in the radial direction of the output body. The output gear has a base portion including an inner surface of the output gear attached to the outer surface of the output body , and the tooth portion attached to the outer peripheral surface of the base portion,
The motor unit according to any one of claims 1 to 4, wherein the base contains more than 50% metal other than aluminum. The motor unit according to any one of claims 1 to 5, wherein the output gear has an outer diameter of 125 mm or less. The motor unit according to any one of claims 1 to 6, wherein the teeth are helical teeth. The motor unit according to any one of claims 1 to 7, wherein the output gear has an outer diameter of 98 mm or less. An electric bicycle comprising the motor unit according to any one of claims 1 to 8.

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