Motor unit and electric bicycle

Abstract

To provide a motor unit and electric bicycle characterized in that power transmission efficiency in a speed reduction mechanism is unlikely to decrease, quietness is easily upgraded, and a case can be readily downsized.SOLUTION: A motor unit 3 includes a case 4, a motor 5 stored in the case 4, an input shaft 6, an output body 8, and a speed reduction mechanism 9. The input shaft 6 pierces the case 4 in the direction of a shaft line 600 and is disposed to be rotatable about the shaft line 600. The output body 8 is disposed in the case 4 to be rotatable about the shaft line 600. The speed reduction mechanism 9 is stored in the case 4, decelerates the rotation of the motor 5, and transmits the resultant rotation to the output body 8. The speed reduction mechanism 9 includes one pair of gears that are engaged with each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a motor unit and an electric bicycle. [Background technology]

[0002] Conventionally, there is known an electrically assisted bicycle equipped with a motor drive unit (see, for example, Patent Document 1). The motor drive unit disclosed in Patent Document 1 includes a unit case, a motor, a crankshaft, a linkage fitted to a sprocket, and a reduction mechanism.

[0003] The reduction mechanism includes two gear pairs: a pair consisting of a toothed portion that rotates integrally with the motor shaft and a large-diameter gear portion that meshes with it, and a pair consisting of a small-diameter gear portion that rotates integrally with the large-diameter gear portion and a large-diameter gear portion that meshes with it as an interlocking body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 184826 Summary of the Invention [Problem to be solved by the invention]

[0005] In electrically assisted bicycles such as those described above, the reduction mechanism uses two pairs of gears to reduce speed, a so-called two-stage reduction mechanism, which means that the power transmission efficiency of the reduction mechanism is likely to decrease, noise levels are likely to decrease, and it is difficult to reduce the size of the unit case.

[0006] In view of the above-mentioned problems in the conventional technology, the present disclosure aims to provide a motor unit and an electric bicycle in which the power transmission efficiency in the reduction mechanism is less likely to decrease, noise reduction can be easily improved, and the case can be easily made smaller. [Means for solving the problem]

[0007] In order to solve the above problem, one embodiment of a motor unit includes a case, a motor housed in the case, an input shaft, an output body, and a reduction mechanism. The input shaft axially passes through the case and is arranged to be rotatable about the axis. The output body is arranged in the case to be rotatable about the axis. The reduction mechanism is housed in the case and reduces the rotation of the motor and transmits it to the output body. The reduction mechanism has only one pair of gears that mesh with each other.

[0008] In order to solve the above problems, an electric bicycle according to one embodiment includes the motor unit. Effect of the Invention

[0009] In the motor unit and electric bicycle according to the above embodiment of the present disclosure, the power transmission efficiency in the reduction mechanism is less likely to decrease, noise reduction can be easily improved, and the case can be easily made smaller. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a side view of the electric bicycle according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along a plane passing through the axes of an output body of a motor unit, a rotating shaft of the motor, and a rotating transmission shaft of a reduction gear mechanism of the electric bicycle. [Diagram 3] FIG. 3 is a side view of the motor unit. [Figure 4] FIG. 4 is a side view of a sprocket and a motor unit in the electric bicycle. [Diagram 5] FIG. 5 is a cross-sectional view taken along a plane passing through the axes of the output body of the motor unit, the rotating shaft of the motor, and the rotating transmission shaft of the reduction gear mechanism according to the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along a plane passing through the axes of the output body of the motor unit, the rotating shaft of the motor, and the rotating transmission shaft of the reduction gear mechanism according to the third embodiment. [Figure 7] FIG. 7 is a side view of the electric bicycle according to the fourth embodiment. [Figure 8] FIG. 8 is a side view of the electric bicycle according to the fifth embodiment. [Figure 9] FIG. 9 is a side view of the motor unit. [Figure 10] FIG. 10 is a side view of the electric bicycle according to the sixth embodiment. [Figure 11] FIG. 11 is a side view of the electric bicycle according to the seventh embodiment. [Figure 12] FIG. 12 is a side view of the electric bicycle according to the eighth embodiment. [Figure 13] FIG. 13 is a side view of the motor unit. [Figure 14] FIG. 14 is a side view of the electric bicycle according to the ninth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present disclosure relates to a motor unit and a two-wheeled vehicle, and more specifically to a motor unit including a case, a motor, an output body, and a reduction mechanism, and to an electric bicycle such as an electrically assisted bicycle or an electric motorcycle including this motor unit.

[0012] A first embodiment of a motor unit and an electric bicycle according to the present disclosure will now be described with reference to Figs.

[0013] As shown in Fig. 1, the electric bicycle 1 includes a frame 10, wheels 11, and a motor unit 3. The electric bicycle 1 has a fixed direction of travel due to its design. In the following description, the direction of travel is defined as forward and the opposite direction is defined as backward, the vertical direction is defined as downward and the opposite direction is defined as upward. Also, as shown in Fig. 2, the left and right directions refer to the left and right directions when facing forward.

[0014] 1, a frame 10 supports a person (hereinafter, referred to as a rider) riding an electric bicycle 1. The weight of the frame 10 and the rider is supported on the ground via a front wheel 111 and a rear wheel 112 that constitute the wheels 11.

[0015] The frame 10 has a head pipe 101, an upper pipe 102, a lower pipe 103, a vertical pipe 104, a seat stay 105, a chain stay 106, and a bracket 2. The frame 10 is made of a metal such as aluminum or stainless steel, but may contain a non-metallic material in part. Moreover, the entire frame 10 may be made of a non-metallic material, and the material of the frame 10 is not particularly limited.

[0016] The head pipe 101 is a cylindrical member that opens generally in the vertical direction. Here, generally in the vertical direction means a direction that forms an angle of about 30 degrees or less with the vertical direction. The handle post 12 is inserted into the head pipe 101 so as to penetrate from top to bottom. The handle post 12 is inserted into the head pipe 101 so as to be rotatable around the axial direction. A front fork 121 is formed at the lower end of the handle post 12. 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 handle bar 122 is provided with a hand operation unit for turning the electric power on and off, and a gear shift operation unit for changing the speed by the gear shift mechanism of the rear wheel 112.

[0017] The upper pipe 102 is a cylindrical member extending generally rearward from the head pipe 101. The upper pipe 102 does not necessarily have to be straight. Note that generally rearward here means a direction forming an angle of about 40 degrees or less with the rear. The front end of the upper pipe 102 is fixed to the side wall on the rear side of the head pipe 101 by welding or the like. The rear end of the upper pipe 102 is fixed to the stand pipe 104.

[0018] The stand pipe 104 is a tubular member that opens generally in the vertical direction. The rear end of the upper pipe 102 is fixed to the front side wall near the upper end of the stand pipe 104 by welding or the like. A shaft extending downward from the saddle 13 is inserted into the opening at the upper end of the stand pipe 104. The saddle 13 is fixed to the stand pipe 104 by fixing this shaft to the stand pipe 104. The bracket 2 is fixed to the lower end of the stand pipe 104.

[0019] The lower pipe 103 is a cylindrical member that extends obliquely downward generally rearward from the head pipe 101. The upper pipe 102 does not necessarily have to be straight. Note that "obliquely downward generally rearward" here means a direction that is lower than the rear and inclined downward from the direction in which the head pipe 101 extends. The front end of the lower pipe 103 is fixed by welding or the like to a portion of the rear side wall of the head pipe 101 that is lower than the portion to which the upper pipe 102 is fixed. A bracket 2 is fixed to the rear end of the lower pipe 103. The bracket 2 is part of the frame 10, and supports the motor unit 3.

[0020] A motor unit 3 is fixed to the underside of the bracket 2 and is supported by the bracket 2. Between the inner surface of the bracket 2 and the outer surface of the motor unit 3, a space for wiring is formed.

[0021] The rear end of the down pipe 103 is fixed to the front end of the bracket 2 by fitting (including shrink fitting), fastening, welding, or the like. The lower end of the upright pipe 104 is fixed to the middle part in the fore-and-aft direction of the bracket 2 by fitting (including shrink fitting), fastening, welding, or the like. 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 that extend roughly rearward from the bracket 2. In the first embodiment, the front end of the cylindrical chain stay 106 is fixed to the rear end of the bracket 2 by welding.

[0022] The front end of the seat stay 105 is fixed to the rear end of the upper pipe 102 by fitting (including shrink fitting), fastening, welding, or the like. The seat stays 105 are two hollow or solid members that extend roughly rearward from near the upper end of the vertical pipe 104. In the first embodiment, the front end of the cylindrical seat stay 105 is fixed by welding or the like. The rear end of the seat stay 105 is fixed to the rear end of the chain stay 106, and the rear wheel 112 is rotatably attached to this part.

[0023] Furthermore, the bracket 2 and the lower pipe 103 have a battery mounting section 16 on which a battery 15 for supplying power to the motor unit 3 is mounted. The battery mounting section 16 also has a plurality of terminals which are electrically connected to a plurality of battery terminals for power supply or signals formed on the lower end of the battery 15. One end of a wire is electrically connected to each of the plurality of terminals.

[0024] Further, through lower pipe 103 and the wiring space, gear shift wires and brake wires that connect the gear shift operation part and the gear shift mechanism are passed.

[0025] The motor unit 3 will be described below with reference to Figures 2 and 3. The motor unit 3 includes a case 4, a motor 5, an input shaft 6, an input body 7, an output body 8, and a reduction mechanism 9.

[0026] The case 4 constitutes an outer shell of the motor unit 3. The case 4 accommodates devices such as the reduction gear mechanism 9 in an accommodation space formed inside. The case 4 is mainly made of a metal such as aluminum, stainless steel, or a magnesium alloy, but a non-metal may also be used, and the material of the case 4 is not particularly limited.

[0027] The case 4 is divided into a first divided body 41 located on the left side and a second divided body 42 located on the right side. The first divided body 41 and the second divided body 42 are combined to form the case 4.

[0028] The second divided body 42 has an internal storage space that is open to the left. The first divided body 41 and the second divided body 42 are fitted together from the left and right so that their respective storage spaces are continuous, and are fixed to each other by fastening members 43 consisting 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. The storage space formed inside the case 4 may or may not be sealed.

[0029] The motor 5 is attached to the case 4. More specifically, the motor 5 is mainly housed in the first divided body 41. The motor 5 is housed in the case 4. The motor 5 has a rotating shaft 51, a rotor 52 that rotates integrally with the rotating shaft 51, and a stator 53. The motor 5 is an inner rotor type in which the stator 53 is located radially outside the rotating shaft 51. Note that an axial gap type motor may be adopted as the motor 5. The rotating shaft 51 is housed rotatably so that the central axis of rotation is parallel to the axis 600. The rotating shaft 51 protrudes from the stator 53 to one side, and a toothed portion 54 that meshes with the reduction mechanism 9 is formed on the outer surface of the protruding portion. The protruding portion of the rotating shaft 51 and the toothed portion 54 formed on the outer surface thereof constitute a gear that rotates integrally with the rotating shaft 51. Both ends of the rotating shaft 51 are supported by a rotating shaft support bearing 551 arranged in the first division 41 and a rotating shaft support bearing 552 arranged in the second division 42. The rotating shaft 51 is provided with a corrugated washer 553 located between the rotating shaft support bearing 552 and the second division 42. By providing this corrugated washer 553, rattling of the rotating shaft 51 can be prevented, and further, the quietness of the motor unit 3 can be improved.

[0030] The diameter 531 of the stator 53 is preferably formed to be 80 mm or less. This makes it easier to miniaturize the motor 5 and the motor unit 3. The diameter 531 of the stator 53 is more preferably formed to be 70 mm or less, which makes it easier to miniaturize the motor 5 and the motor unit 3. The diameter 531 of the stator 53 is preferably formed to be equal to or greater than the outer diameter (diameter) of the rotating shaft 51, which makes it possible to stabilize the torque obtained from the rotating shaft 51 of the motor 5. For example, the outer diameter of the rotating shaft 51 is 8 mm.

[0031] The input shaft 6 penetrates the case 4 in the direction of an axis 600 (left-right direction in the first embodiment) and is arranged to be rotatable around the axis 600 of the input shaft 6. The input shaft 6 has an input shaft body 60 and an input body 7. In the first embodiment, the input shaft body 60 is made of a solid member, but may be made of a hollow member.

[0032] The case 4 has a first bearing 45, which rotatably supports the input shaft body 60, at one end side in the direction of the axis 600 (the left end side in the first embodiment). An input shaft hole 411 through which the input shaft body 60 passes is formed in the first divided body 41, and the first bearing 45 is disposed in this input shaft hole 411. In the first embodiment, the first bearing 45 is configured by a ball bearing. Note that the first bearing 45 is not limited to a ball bearing and various other bearings, such as a roller bearing, can also be used.

[0033] The case 4 also has a second bearing 46 that rotatably supports the output body 8 at the other end side in the direction of the axis 600 (the right end side in the first embodiment). An input shaft hole 421 through which the input shaft body 60 passes is formed in the second divided body 42, and the second bearing 46 is disposed in this input shaft hole 421. In the first embodiment, the input shaft body 60 is indirectly supported by the second bearing 46 via the output body 8. In the first embodiment, the second bearing 46 is configured by a ball bearing. Note that the second bearing 46 is not limited to a ball bearing and various other bearings such as a roller bearing can also be used.

[0034] 1, one end of a crank arm 18 is fixed to the end of the input shaft body 60. A pedal 181 is rotatably attached to the other end of the crank arm 18. The rider of the electric bicycle 1 can transmit human power to the input shaft body 60 by pedaling the pedal 181.

[0035] As shown in FIG. 2, the input body 7 is disposed along the outer circumferential surface of the input shaft body 60 and rotates integrally with the input shaft body 60. The input body 7 is a cylindrical member, and its axis 600 faces the left-right direction and is disposed concentrically with the input shaft body 60. The length of the input body 7 in the left-right direction is shorter than the length of the input shaft body 60 in the left-right direction. The input body 7 and the input shaft body 60 have fitting portions 71, 61 in a part in the axis 600 direction, which fit with each other so as to be relatively unrotatable around the axis 600. In the first embodiment, the fitting portions 71, 61 made of a spline portion or a serration portion are formed on the left end portion of the input body 7 and the input shaft body 60 corresponding to this portion. The fitting portions 71, 61 may be configured to be fitted with male and female threads.

[0036] Furthermore, in the first embodiment, the input body 7 is connected to the input shaft body 60. A gap 70 is formed between the input body 7 and the input shaft body 60. This makes it easier to insert the input shaft body 60 into the cylindrical input body 7.

[0037] The output body 8 is disposed rotatably 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 input body 7 and the output body 8 have a connecting portion that connects the input body 7 and the output body 8 so that they rotate integrally. A fitting portion 72 made of a spline portion made of concaves and convexes arranged side by side in the circumferential direction is formed on the outer peripheral surface of the input body 7. Similarly, a fitting portion 81 made of a spline portion made of concaves and convexes arranged side by side in the circumferential direction and meshing with the fitting portion 72 made of a spline portion is formed on the inner peripheral surface of the output body 8. The fitting portion 72 and the fitting portion 81 form a connecting portion.

[0038] The output body 8 is a generally cylindrical member with its axis 600 oriented in the left-right direction and arranged concentrically with the input shaft body 60. The left-right length of the output body 8 is shorter than the left-right length of the input shaft body 60. The right end of the output body 8 protrudes outside the case 4 through an input shaft hole 421 formed in the second divided body 42. The output body 8 is supported by a second bearing 46 arranged in the second divided body 42. The output body 8, together with the input shaft body 60 and the input body 7, constitutes the rotating shaft unit 30. The rotating shaft unit 30 is supported by the case 4 via a first bearing 45 and a second bearing 46.

[0039] It is preferable that the rotating shaft 51 of the motor 5 is located above the axis 600 and behind the axis 600 in the traveling direction of the electric bicycle 1. This makes it easier to align the case 4 with the stand pipe 104. The rotating shaft 51 of the motor 5 may also be located below the axis 600. In this case, the center of gravity of the electric bicycle 1 can be lowered, and stability can be improved. Also, in a configuration in which the battery 15 is built into the stand pipe 104 described below, it becomes easier to ensure storage space within the stand pipe 104.

[0040] The pitch 511 between the rotating shaft 51 of the motor 5 and the output body 8 is preferably 60 mm or less. The pitch 511 refers to the distance between the axis that is the center of rotation of the rotating shaft 51 and the axis (axis 600) that is the center of rotation of the output body 8. By forming the pitch 511 to be 60 mm or less, it becomes easier to reduce the size of the case 4 (motor unit 3). Furthermore, it is more preferable that the pitch 511 is formed to be 55 mm or less, which makes it even easier to reduce the size of the case 4 (motor unit 3). Furthermore, it is more preferable that the pitch 511 is formed to be 50 mm or less, which makes it even easier to reduce the size of the case 4 (motor unit 3). Furthermore, it is more preferable that the pitch 511 is formed to be 45 mm or less, which makes it even easier to reduce the size of the case 4 (motor unit 3). Furthermore, it is preferable that the pitch 511 is formed to be equal to or greater than the outer diameter (diameter) of the input shaft 6. This makes it possible to set an appropriate reduction ratio in the reduction mechanism 9.

[0041] A front sprocket 191 is attached to a portion of the output body 8 protruding outside the case 4. The front sprocket 191 is attached to the output body 8 on either side in the direction of the axis 600. In the first embodiment, the front sprocket 191 is fixed to a portion of the output body 8 protruding to the right side of the case 4 by a lock ring 195. The front sprocket 191 rotates integrally with the output body 8. In addition, as shown in FIG. 1, a rear sprocket 192 is fixed to the hub of the rear wheel 112. A chain 193 is wound between the front sprocket 191 and the rear sprocket 192.

[0042] 4, when viewed from the direction of axis 600, the outer contour of case 4 is contained within the outer contour of sprocket 191. This improves the appearance of electric bicycle 1 and increases the freedom in designing electric bicycle 1.

[0043] 2, a connecting portion consisting of fitting portion 72 and fitting portion 81 is formed on the input body 7 (input shaft 6) and the output body 8, so that the input shaft 6 and the output body 8 rotate integrally, and the rotation speed of the input shaft 6 matches the rotation speed of the output body 8. As a result, the phase of rotation of the input shaft 6 (input shaft body 60 and input body 7), the output body 8, and the front sprocket 191 about the axis 600 is fixed.

[0044] Furthermore, when a so-called coaster brake is employed, such a connecting portion functions effectively. A coaster brake applies a brake in the hub of the rear wheel 112 via the chain 193 by the rotational force generated when the front sprocket 191 rotates in the counter-acceleration direction. With the above configuration, the input shaft 6 and the output body 8 can rotate integrally, so that the coaster brake can function smoothly. Note that the fitting portions 72 and 81 as connecting portions are not limited to spline portions, and may be formed of serration portions, or, 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.

[0045] A gear 90 constituting the reduction mechanism 9 is attached to the output body 8. The gear 90 has teeth 91 on its outer circumferential surface. The gear 90 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, a one-way clutch 32 is provided between the reduction mechanism 9 and the output body 8. Specifically, the gear 90 is connected to the output body 8 via the one-way clutch 32. The one-way clutch 32 is disposed on the outer periphery of the output body 8, and the central axis of rotation of the one-way clutch 32 is located on the axis 600. This eliminates the need to dispose the one-way clutch 32 in a portion apart from the input shaft 6 and the output body 8 in the case 4, and makes it easier to form a space in a portion apart from the input shaft 6 and the output body 8 in the case 4.

[0046] When a rotational force is applied from the motor 5 to the gear 90 in a direction that accelerates 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 when a rotational force is applied in the opposite direction to the acceleration direction, the one-way clutch 32 does not transmit this rotational force to the output body 8. Also, when a rotational force in the acceleration direction is applied to the output body 8, the one-way clutch 32 does not transmit this rotational force to the gear 90.

[0047] The reduction mechanism 9 is housed in the case 4, and reduces the speed of the rotation of the motor 5 before transmitting it to the output body 8. The reduction mechanism 9 has only one pair of gears that mesh with each other. Specifically, the reduction mechanism 9 includes a driving gear (a portion protruding from the rotating shaft 51 and having a toothed portion 54 formed thereon) that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The reduction mechanism 9 reduces the speed of the rotation of the motor 5 by so-called single-stage reduction before transmitting it to the output body 8.

[0048] The number of teeth of the driving gear, i.e., the number of teeth in the toothed portion 54, is preferably 9 or less. This allows the reduction ratio by meshing between the driving gear and the driven gear 90 to be large, making it easier to achieve the desired reduction ratio even in one-stage reduction, and making it easier to miniaturize the reduction mechanism 9 and the motor unit 3. In addition, the number of teeth of the driving gear is more preferably 5 or less. This allows the reduction ratio by meshing between the driving gear and the driven gear 90 to be even larger, making it easier to achieve the desired reduction ratio even in one-stage reduction, making it easier to miniaturize the reduction mechanism 9 and the motor unit 3. In addition, the number of teeth of the driving gear is more preferably 4 or less. This allows the reduction ratio by meshing between the driving gear and the driven gear 90 to be even larger, making it easier to achieve the desired reduction ratio even in one-stage reduction, making it easier to miniaturize the reduction mechanism 9 and the motor unit 3.

[0049] In addition, it is preferable that the surface of the driving gear (the surface of the teeth 54) is shot peened, air blasted, plated or has a coating.

[0050] Examples of shot peening include hard shot peening, semi-hard shot peening, WPC treatment, molybdenum disulfide shot peening, and Sirius processing. By subjecting the surface of the driving gear to shot peening, the surface roughness of the driving gear is improved and the slipperiness of the driving gear surface is increased, so that the frictional resistance between the driving gear and the driven gear 90 is reduced, and the effects of suppressing noise during driving and suppressing wear of the driven gear 90 are obtained. In addition, the wear resistance of the driving gear is improved, and heat generation at the meshing portion between the driving gear and the driven gear 90 is suppressed.

[0051] Air blasting includes, for example, air blasting using #100 media and air blasting using #400 media. By performing air blasting on the surface of the driving gear, the surface roughness of the driving gear is improved and the slipperiness of the surface of the driving gear is increased, thereby reducing frictional resistance between the driving gear and driven gear 90, thereby suppressing noise during driving and wear of the driven gear 90.

[0052] Coatings include DLC (Diamond-Like Carbon) coating, Teflon (registered trademark) coating, dry lube treatment, alumite treatment, hard alumite treatment, molybdenum disulfide coating, and various plating treatments. Various plating treatments include, for example, hard chrome plating, electrolytic hard chrome carbide plating, trivalent chromate plating, nickel plating, electroless nickel plating, fluorine composite electroless nickel plating, fluorine composite electroless nickel plating, and Parker treatment.

[0053] By applying the above-mentioned coating to the surface of the drive side gear, the surface roughness of the drive side gear is improved and the surface slipperiness of the drive side gear is increased, so that the frictional resistance between the drive side gear and the driven side gear 90 is reduced, and the effects of suppressing noise during driving and suppressing wear of the driven side gear 90 are obtained. In addition, it is preferable that the drive side gear is polished. By polishing, the surface roughness of the gear surface is reduced and the slipperiness of the drive side gear surface is increased. As a result, the frictional resistance between the drive side gear and the driven side gear 90 is reduced, and the effects of suppressing noise during driving and suppressing wear of the driven side gear 90 are obtained.

[0054] It is preferable that at least a part of the driven gear 90 is made of resin. Making at least a part of the gear 90 of resin includes making at least the teeth of the gear 90 of resin. The driven gear 90 is a gear molded into a cylindrical shape using resin as a material. Specifically, the resin is polyacetal, but other resins such as nylon can also be used.

[0055] Polyacetal is a self-lubricating material. By molding the driven gear 90 from polyacetal, wear of the driven gear 90 is suppressed, which has the effect of suppressing noise during driving and increasing durability.

[0056] Generally, the driven gear included in the reduction mechanism tends to be large in diameter and heavy, but in the first embodiment, the driven gear 90 is molded from a resin such as polyacetal, thereby realizing a reduction in weight of the reduction mechanism 9 and, in turn, a reduction in weight of the entire electric bicycle 1. In addition, the reduction in weight of the driven gear 90 reduces the rotational moment of the driven gear 90, realizing a swift operation when the electric bicycle 1 is driven by the motor 5.

[0057] In comparison with the case where the material of the driven gear 90 is assumed to be nylon, if the material of the driven gear 90 is polyacetal, there are advantages in that durability is further improved and that it can be provided at a relatively low cost. Note that polyacetal is weak against heat and its durability decreases at high temperatures, but since the reduction gear mechanism 9 is a single-stage reduction gear, the rotation of the driven gear 90 is slower and it is less likely to become hot and its durability is less likely to decrease compared to a two-stage reduction gear.

[0058] Polyacetal is classified into two types, homopolymer and copolymer, based on its molecular structure. Either type of polyacetal, homopolymer or copolymer, can be used as the material for the driven gear 90.

[0059] The diameter 901 of the driven gear 90 is preferably 110 mm or less. This makes it easier to miniaturize the reduction gear 9 and the motor unit 3. The diameter 901 of the gear 90 is more preferably 95 mm or less, which makes it easier to miniaturize the reduction gear 9 and the motor unit 3. The diameter 901 of the gear 90 is more preferably 80 mm or less, which makes it easier to miniaturize the reduction gear 9 and the motor unit 3. The diameter 901 of the gear 90 is preferably equal to or greater than the diameter of the rotating shaft 51. This makes it easier to ensure the holding rigidity of the gear 90, prevents the gear 90 from falling, and improves the noise reduction and durability of the gear. Furthermore, by reducing the outer diameter of the gear 90, it is possible to reduce the fall of the helical gear due to a load in the thrust direction (axis 600 direction), thereby improving the noise reduction and durability of the reduction gear 9.

[0060] Moreover, it is preferable that the driving gear and the driven gear 90 are helical gears, which improves durability and improves the meshing ratio and noise reduction compared to when they are spur gears.

[0061] When the rider pedals 181 of the electric bicycle 1, a rotational force in the acceleration direction is applied to the input shaft body 60. When the input shaft body 60 rotates, the input body 7 rotates integrally with the input shaft body 60. The rotational force in the acceleration direction of the input body 7 is applied to the output body 8, and the output body 8 and the front sprocket 191 rotate in the acceleration direction. When the front sprocket 191 rotates in the acceleration direction, a rotational force in the acceleration direction is applied to the rear sprocket 192 via the chain 193, and the rear sprocket 192 and the rear wheel 112 rotate in the acceleration direction. This causes the electric bicycle 1 to move forward in the forward direction.

[0062] Also, while the electric bicycle 1 is moving forward in the forward direction by human power, the rotational force from the motor 5 can be applied to the output body 8 as an auxiliary force. This will be explained in detail below. When the rotating shaft 51 of the motor 5 rotates in the acceleration direction, the gear 90 that meshes with the gear (tooth portion 54) that rotates integrally with the rotating shaft 51 of the motor 5 rotates in the acceleration direction. The rotational force of the gear 90 in the acceleration direction is transmitted to the output body 8 via the one-way clutch 32. In other words, the output body 8 functions as a force combiner that combines the rotational force of human power from the input body 7 and the rotational force from the motor 5. The motor unit 3 in the first embodiment is a so-called single-shaft motor unit 3.

[0063] 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 rotation speed per unit time of the input shaft 60. The torque applied to the input shaft 60 is detected by a torque detection unit 33. The torque detection unit 33 is disposed along the surface of the input shaft 6, and detects the torque applied to the input shaft 6.

[0064] In the first embodiment, a magnetostrictive generating part 331 having magnetic anisotropy is formed on the outer peripheral surface of the input body 7. In addition, a coil 332 is disposed at a slight distance from the portion of the outer peripheral surface of the input body 7 where the magnetostrictive generating part 331 is provided. The magnetostrictive generating part 331 and the coil 332 constitute a magnetostrictive torque sensor as the torque detection part 33. Various types of magnetostrictive torque sensors can be appropriately used as such a magnetostrictive torque sensor. In addition, the torque detection part 33 is not limited to a magnetostrictive torque sensor.

[0065] The number of rotations per unit time of the input shaft 60 is detected by the input shaft rotation detection unit 34. The input shaft rotation detection unit 34 has a detected portion 344 attached to the rotating shaft unit 30 and a detection portion 345 fixed to a portion other than the rotating shaft unit 30.

[0066] In the first embodiment, the rotor 341 is attached to the outer circumferential surface of the input shaft body 60. The rotor 341 is attached by press-fitting the outer circumferential surface of the input shaft body 60 into the inner circumferential surface of the rotor 341. The rotor 341 rotates integrally with the input shaft body 60. The rotor 341 has teeth at the tip of a portion extending in the radial direction of the input shaft 6. A rotor 342 having teeth meshing with the teeth is rotatably attached on the rotation orbit of the teeth of the rotor 341. A rotor 343 having teeth meshing with the teeth is rotatably attached on the rotation orbit of the teeth of the rotor 342. The rotor 343 extends in the direction of the axis 600 of the input shaft 6, and has magnets arranged at regular intervals in the circumferential direction as the detection target portion 344 at its tip. The rotors 341 to 343 are for allowing the input shaft rotation detection unit 34 to detect the rotation speed of the input shaft 6.

[0067] Furthermore, as the detection unit 345, a Hall IC that detects the magnetic force of the magnet is disposed at a position corresponding to the rotational orbit of the magnet that is the detected unit 344. The detection unit 345 is attached to the control board 35, which will be described later. By directly attaching the detection unit 345 to the control board 35, connectors and wiring that connect the detection unit 345 and the control board 35 are not required, making it easier to miniaturize the motor unit 3.

[0068] It should be noted that various types of detectors can be appropriately used as the input shaft rotation detector 34 having such a magnet and a Hall IC. Also, the input shaft rotation detector 34 is not limited to one having a magnet and a Hall IC.

[0069] Rotating body 341 is located on the opposite side of torque detection unit 33 to the side on which sprocket 191 is located in the direction of axis 600. In terms of torque detection unit 33, sprocket 191 is located on the right side, while rotating body 341 is located on the left side. This allows rotating body 341 to be located away from sprocket 191, improving design freedom.

[0070] The motor unit 3 further has a motor rotation detection section 36 that detects the number of rotations of the rotor 52. The motor rotation detection section 36 has a detection section 361. As the detection section 361, a Hall IC that detects the magnetic force of the rotor 52 is disposed at a position corresponding to the rotational orbit of the rotor 52 of the motor 5. The magnetic force detected by the Hall IC may be the magnetic force of the rotor 52 itself, or may be the magnetic force of a member that rotates together with the rotor 52. The detection section 361 is attached to the control board 35. By directly attaching the detection section 361 to the control board 35, a connector or wiring that connects the detection section 361 and the control board 35 is not required, making it easier to miniaturize the motor unit 3.

[0071] Various types of motor rotation detector 36 having such a magnet and Hall IC can be appropriately used. In addition, motor rotation detector 36 is not limited to one having a magnet and Hall IC. In addition, a sensor other than a Hall IC can be used as detector 361. For example, a resolver or an optical sensor can be used as detector 361.

[0072] The motor unit 3 has a control board 35 disposed in a case 4, the control board 35 having a control unit for controlling the motor 5. The control unit has, for example, a microcomputer, and controls the operation of each element by executing a program stored in a storage unit such as a ROM (Read Only Memory). Various types of control units can be used as appropriate, and detailed descriptions 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 input shaft rotation detection unit 34.

[0073] In the electric bicycle 1 of the first embodiment, the reduction mechanism 9 has only one pair of gears that mesh with each other, so the power transmission efficiency in the reduction mechanism 9 is less likely to decrease, noise reduction can be improved, and the case 4 (motor unit 3) and the electric bicycle 1 can be made more compact. In particular, by making the case 4 more compact, the so-called rear-center distance from the center of the rear wheel 112 to the axis 600 of the input shaft 60 can be shortened, making the electric bicycle 1 easier to handle.

[0074] Next, the motor unit 3 of the second embodiment will be described with reference to Fig. 5. Note that since the motor unit 3 of the second embodiment is mostly the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0075] 2, in the first embodiment, the rotating shaft support bearing 551 that supports the rotating shaft 51 is located to the left of the first bearing 45 that supports the input shaft body 60 (opposite the front sprocket 191). In contrast, in the second embodiment, the rotating shaft support bearing 551 is located at a position overlapping with the first bearing 45 in the direction of the axis 600. This makes it easier to make the left side surface of the case 4 flat and simple.

[0076] Next, the motor unit 3 of the third embodiment will be described with reference to Fig. 6. Note that since the motor unit 3 of the third embodiment is largely the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0077] In the first embodiment, as shown in Fig. 2, three rotors 341 to 343 are provided as rotors for causing the input shaft rotation detection unit 34 to detect the rotation speed of the input shaft 6. In contrast, in the third embodiment, as shown in Fig. 6, only one rotor 346 is provided.

[0078] In the first embodiment, as shown in Fig. 2, the rotor 341 attached to the input shaft 6 is located on the left side of the torque detection unit 33. In contrast, in the third embodiment, as shown in Fig. 6, the rotor 346 attached to the input shaft 6 is located on the right side of the torque detection unit 33.

[0079] In the third embodiment, since only one rotating body 346 is provided, it is easy to reduce the size of the case 4 (motor unit 3) and the size of the electric bicycle 1.

[0080] Next, the motor unit 3 of the fourth embodiment will be described with reference to Fig. 7. Note that since the motor unit 3 of the fourth embodiment is mostly the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0081] In the first embodiment, as shown in Fig. 2, the battery 15 is exposed as a part of the surface of the down pipe 103. In contrast, in the fourth embodiment, as shown in Fig. 7, the battery 15 is built into the down pipe 103, making the battery 15 less likely to be stolen.

[0082] Next, the motor unit 3 of the fifth embodiment will be described with reference to Figures 8 and 9. Note that since the motor unit 3 of the fifth embodiment is mostly the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0083] In the first embodiment, as shown in Fig. 2, the battery 15 is provided in the down pipe 103. In contrast, in the fifth embodiment, as shown in Fig. 8, the battery 15 is built into the upright pipe 104. Wiring connected to the battery 15 is connected to a connector 37 of the motor unit 3 as shown in Fig. 9. The connector 37 is formed at the upper end of the case 4.

[0084] In the fifth embodiment, the battery 15 is built into the stand pipe 104, which improves the degree of freedom in designing the down pipe 103. In addition, since the battery 15 is built into the stand pipe 104, it is less likely to be stolen.

[0085] Next, a motor unit 3 according to a sixth embodiment will be described with reference to Fig. 10. Note that since the motor unit 3 according to the sixth embodiment is largely the same as the motor unit 3 according to the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0086] In the first embodiment, as shown in Fig. 2, the battery 15 is provided in the lower pipe 103. In contrast, in the sixth embodiment, as shown in Fig. 10, the battery 15 is built into the upper pipe 102.

[0087] In the sixth embodiment, the battery 15 is built into the upper pipe 102, which improves the degree of freedom in designing the lower pipe 103. In addition, since the battery 15 is built into the upper pipe 102, it is less likely to be stolen.

[0088] Next, the motor unit 3 of the seventh embodiment will be described with reference to Fig. 11. Note that since the motor unit 3 of the seventh embodiment is mostly the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0089] In the first embodiment, as shown in Fig. 2, the battery 15 is provided on the down pipe 103. In contrast, in the seventh embodiment, as shown in Fig. 11, the battery 15 is provided on the hub of the front wheel 111. This improves the degree of freedom in designing the frame 10.

[0090] Next, the motor unit 3 of the eighth embodiment will be described with reference to Figures 12 and 13. Note that since the motor unit 3 of the eighth embodiment is mostly the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0091] In the first embodiment, as shown in Fig. 2, the rotating shaft 51 of the motor 5 is located above the axis 600 and rearward of the axis 600 in the traveling direction of the electric bicycle 1. In contrast, in the eighth embodiment, as shown in Fig. 12, the rotating shaft 51 of the motor 5 is located above the axis 600 and forward of the axis 600 in the traveling direction of the electric bicycle 1. The wiring connected to the battery 15 is connected to a connector 37 of the motor unit 3 as shown in Fig. 13. The connector 37 is formed on the side of the case 4.

[0092] In the eighth embodiment, it becomes easier to shorten the distance between the battery 15 and the motor 5, and it becomes easier to shorten the length of the wiring.

[0093] Next, the motor unit 3 of the ninth embodiment will be described with reference to Fig. 14. Note that since the motor unit 3 of the ninth embodiment is largely the same as the motor unit 3 of the first embodiment, a description of the same parts will be omitted and differences will be mainly described.

[0094] In the first embodiment, as shown in Fig. 2, the rotating shaft 51 of the motor 5 is located above the axis 600 and behind the axis 600 in the traveling direction of the electric bicycle 1. In contrast, in the ninth embodiment, as shown in Fig. 14, the rotating shaft 51 of the motor 5 is located above the axis 600 and ahead of the axis 600 in the traveling direction of the electric bicycle 1. In addition, the motor unit 3 has a terminal 38 connected to a battery 15 for supplying power to the motor unit 3.

[0095] In the ninth embodiment, the battery 15 can be directly connected to the terminal 38 of the motor unit 3, eliminating the need for wiring to connect the battery 15 and the motor unit 3. If the terminal 38 fits within the outer casing of the sprocket 191 when viewed in the direction of the axis 600, the motor unit 3 can be made smaller. If the terminal 38 does not fit within the outer casing of the sprocket 191 when viewed in the direction of the axis 600, the possibility of the user's hand interfering with the sprocket 191 when attaching the battery 15 can be reduced.

[0096] As a modification of the above embodiment, a one-way clutch may be disposed between the input body 7 and the output body 8. When a rotational force in the accelerating direction is applied to the input body 7, the one-way clutch transmits this rotational force to the output body 8, and when a rotational force in the direction opposite to the accelerating direction is applied, the one-way clutch does not transmit this rotational force to the output body 8. Also, when a rotational force in the accelerating direction is applied to the output body 8, the one-way clutch does not transmit this rotational force to the input body 7.

[0097] A one-way clutch may be disposed between the input shaft 6 and the input body 7. In this case, the one-way clutch transmits a rotational force to the input body 7 when a rotational force in the accelerating direction is applied to the input shaft 6, and does not transmit the rotational force to the input body 7 when a rotational force in the opposite direction to the accelerating direction is applied. In addition, the one-way clutch does not transmit a rotational force to the input shaft 6 when a rotational force in the accelerating direction is applied to the input body 7. In this way, when a one-way clutch is disposed between the input body 7 and the output body 8, or between the input shaft 6 and the input body 7, the input shaft 6 does not rotate together with the sprocket 191 even if the sprocket 191 rotates in the accelerating direction. Therefore, it is useful when the electric bicycle is driven only by the driving force of the motor 5. For example, the electric bicycle is driven only by the driving force of the motor 5 in a push-walk control (walk mode).

[0098] As is apparent from the above-described embodiment and its modified examples, the motor unit 3 of the first aspect includes a case 4, a motor 5 housed in the case 4, an input shaft 6, an output body 8, and a reduction mechanism 9. The input shaft 6 passes through the case 4 in the direction of an axis 600 and is arranged so as to be rotatable about the axis 600. The output body 8 is arranged in the case 4 so as to be rotatable about the axis 600. The reduction mechanism 9 is housed in the case 4, and reduces the rotation of the motor 5 and transmits it to the output body 8. The reduction mechanism 9 has only one pair of gears that mesh with each other.

[0099] According to the first aspect, the power transmission efficiency in the reduction mechanism 9 is less likely to decrease, noise reduction can be easily improved, and the size of the case 4 can be easily reduced.

[0100] The second aspect can be realized by combining with the first aspect. In the second aspect, the motor 5 is an inner rotor type motor.

[0101] According to the second aspect, the motor 5 can be configured as an inner rotor type motor, which is widely used.

[0102] The third aspect can be realized by combining with the first or second aspect. In the third aspect, the motor unit 3 further includes a sprocket 191 attached to the output body 8. When viewed from the direction of the axis 600, the outer contour of the case 4 is contained within the outer contour of the sprocket 191.

[0103] According to the third aspect, the appearance of the electric bicycle 1 having the motor unit 3 is improved, and the freedom in designing the electric bicycle 1 is increased.

[0104] The fourth aspect can be realized by combining with any one of the first to third aspects. In the fourth aspect, the diameter 531 of the stator 53 of the motor 5 is 80 mm or less.

[0105] According to the fourth aspect, the motor 5 and the motor unit 3 can be easily reduced in size.

[0106] The fifth aspect can be realized by combining with any one of the first to third aspects. In the fifth aspect, the diameter 531 of the stator 53 of the motor 5 is 70 mm or less.

[0107] According to the fifth aspect, the motor 5 and the motor unit 3 can be made even more compact.

[0108] The sixth aspect can be realized by combining with any one of the first to fifth aspects. In the sixth aspect, the pitch 511 between the rotary shaft 51 and the output body 8 of the motor 5 is 60 mm or less.

[0109] According to the sixth aspect, the case 4 (motor unit 3) can be easily reduced in size.

[0110] The seventh aspect can be realized by combining with any one of the first to fifth aspects. In the seventh aspect, the pitch 511 between the rotary shaft 51 and the output body 8 of the motor 5 is 55 mm or less.

[0111] According to the seventh aspect, it becomes easier to reduce the size of the case 4 (motor unit 3).

[0112] The eighth aspect can be realized by combining with any one of the first to seventh aspects. In the eighth aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The diameter 901 of the driven gear 90 is 110 mm or less.

[0113] According to the eighth aspect, the reduction gear mechanism 9 and the motor unit 3 can be easily reduced in size.

[0114] The ninth aspect can be realized by combining with any one of the first to seventh aspects. In the ninth aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The diameter 901 of the driven gear 90 is 95 mm or less.

[0115] According to the ninth aspect, the reduction gear mechanism 9 and the motor unit 3 can be made even more compact.

[0116] The tenth aspect can be realized by combining with any one of the first to ninth aspects. In the tenth aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The driving gear has nine or less teeth.

[0117] According to the tenth aspect, a large reduction ratio can be achieved by meshing the driving gear and the driven gear 90, making it easier to achieve a desired reduction ratio even in one-stage reduction, and making it easier to reduce the size of the reduction mechanism 9 and the motor unit 3.

[0118] The eleventh aspect can be realized by combining with any one of the first to ninth aspects. In the eleventh aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The number of teeth of the driving gear is four or less.

[0119] According to the eleventh aspect, the reduction ratio due to the meshing of the driving gear and the driven gear 90 can be made even larger, making it easier to achieve the desired reduction ratio even in one-stage reduction, and making it even easier to reduce the size of the reduction mechanism 9 and the motor unit 3.

[0120] The twelfth aspect can be realized by combining with any one of the first to eleventh aspects. In the twelfth aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. At least a part of the driven gear 90 is made of resin.

[0121] According to the twelfth aspect, wear of the driven gear 90 is easily suppressed, and noise during driving is easily suppressed.

[0122] The thirteenth aspect can be realized in combination with the twelfth aspect. In the thirteenth aspect, the resin is a polyacetal resin.

[0123] According to the thirteenth aspect, wear of the driven gear 90 is easily suppressed, and noise during driving is easily suppressed.

[0124] The fourteenth aspect can be realized by combining with any one of the first to thirteenth aspects. In the fourteenth aspect, the reduction gear 9 includes a driving gear that rotates integrally with the rotating shaft 51 of the motor 5, and a driven gear 90 that rotates integrally with the output body 8. The surface of the driving gear is shot peened, air blasted, plated, ground, rolled, forged, or coated.

[0125] According to the fourteenth aspect, the surface roughness of the driving gear is improved and the slipperiness of the surface of the driving gear is increased, thereby reducing the frictional resistance between the driving gear and the driven gear 90, making it easier to suppress noise during driving and to suppress wear of the driven gear 90.

[0126] The fifteenth aspect can be realized by combining with any one of the first to fourteenth aspects. In the fifteenth aspect, the motor unit 3 further includes a control board 35 and a motor rotation detector 36. The control board 35 has a control unit that controls the motor 5. The motor rotation detector 36 detects the number of rotations of the rotor 52 of the motor 5. The motor rotation detector 36 is provided on the control board 35.

[0127] According to the fifteenth aspect, connectors and wiring for connecting the motor rotation detector 36 and the control board 35 become unnecessary, and the motor unit 3 can be easily made smaller.

[0128] The sixteenth aspect can be realized by combining with any one of the first to fifteenth aspects. In the sixteenth aspect, the motor unit 3 further includes a control board 35 and an input shaft rotation detection unit 34. The control board 35 has a control unit that controls the motor 5. The input shaft rotation detection unit 34 detects the number of rotations of the input shaft 6. The input shaft rotation detection unit 34 is provided on the control board 35.

[0129] According to the sixteenth aspect, the connector and wiring for connecting the input shaft rotation detection unit 34 and the control board 35 become unnecessary, and the motor unit 3 can be easily made smaller.

[0130] The seventeenth aspect can be realized by combining with any one of the first to sixteenth aspects. In the seventeenth aspect, the motor unit 3 further includes a torque detection unit 33. The torque detection unit 33 is disposed along the surface of the input shaft 6 and detects the torque applied to the input shaft 6. The output body 8 and the input shaft 6 are fitted to each other by fitting portions 72, 81 formed of a spline portion or a serration portion.

[0131] According to the seventeenth aspect, since the torque and bending moment from the output body 8 are not easily transmitted to the input shaft 6, detection of the torque of the input shaft 6 is not easily influenced by the torque and bending moment from the output body 8.

[0132] The eighteenth aspect can be realized by a combination with any one of the first to seventeenth aspects. In the eighteenth aspect, the motor unit 3 further includes a sprocket 191, a torque detection unit 33, an input shaft rotation detection unit 34, and a rotor 341. The sprocket 191 is attached to the output body 8 on either side in the direction of the axis 600. The torque detection unit 33 is disposed along the surface of the input shaft 6 and detects the torque applied to the input shaft 6. The input shaft rotation detection unit 34 detects the number of revolutions of the input shaft 6. The rotor 341 is for causing the input shaft rotation detection unit 34 to detect the number of revolutions of the input shaft 6, and is attached to the input shaft 6 so as to rotate integrally with the input shaft 6. The rotor 341 is located on the opposite side of the torque detection unit 33 from the side on which the sprocket 191 is located in the direction of the axis 600.

[0133] According to the eighteenth aspect, the rotor 341 can be disposed at a position separated from the sprocket 191, improving the degree of freedom in design.

[0134] The nineteenth aspect can be realized by a combination with any one of the first to seventeenth aspects. In the nineteenth aspect, the motor unit 3 further includes a sprocket 191, a torque detection unit 33, an input shaft rotation detection unit 34, and a rotor 341. The sprocket 191 is attached to the output body 8 on either side in the direction of the axis 600. The torque detection unit 33 is disposed along the surface of the input shaft 6 and detects the torque applied to the input shaft 6. The input shaft rotation detection unit 34 detects the number of revolutions of the input shaft 6. The rotor 341 is for causing the input shaft rotation detection unit 34 to detect the number of revolutions of the input shaft 6, and is attached to the input shaft 6 so as to rotate integrally with the input shaft 6. The rotor 341 is located on the side where the sprocket 191 is located with respect to the torque detection unit 33 in the direction of the axis 600.

[0135] According to the nineteenth aspect, the rotor 341 can be disposed in a position close to the sprocket 191, improving the degree of freedom in design.

[0136] The twentieth aspect can be realized by combining with any one of the first to nineteenth aspects. In the twentieth aspect, the pair of gears of the reduction mechanism 9 are helical gears.

[0137] According to the twentieth aspect, the durability of the pair of gears of the reduction gear mechanism 9 is improved, and the meshing ratio is improved, resulting in improved quietness.

[0138] The twenty-first aspect can be realized by combining with any one of the first to twentieth aspects. In the twenty-first aspect, the motor unit 3 has a terminal 38 connected to the battery 15 for supplying power to the motor unit 3.

[0139] According to the twenty-first aspect, the wiring for connecting the battery 15 and the motor unit 3 becomes unnecessary.

[0140] The 22nd aspect can be realized by combining with any one of the 1st to 21st aspects. In the 22nd aspect, the electric bicycle 1 includes the motor unit 3 according to any one of the 1st to 21st aspects.

[0141] According to the twenty-second aspect, the power transmission efficiency in the reduction mechanism 9 is less likely to decrease, noise reduction can be easily improved, and the size of the case 4 can be easily reduced.

[0142] The 23rd aspect can be realized by combining with the 22nd aspect. In the 23rd aspect, the rotating shaft 51 of the motor 5 is located above the axis 600 and behind the axis 600 in the traveling direction of the electric bicycle 1.

[0143] According to the twenty-third aspect, the case 4 can be easily aligned along the stand pipe 104.

[0144] The 24th aspect can be realized by combining with the 22nd aspect. In the 24th aspect, the rotating shaft 51 of the motor 5 is located below the axis 600.

[0145] According to the twenty-fourth aspect, the degree of freedom in design is improved.

[0146] The 25th aspect can be realized by combining with any of the 22nd to 24th aspects. In the 25th aspect, the electric bicycle 1 includes a battery 15 for supplying power to the motor unit 3, and a frame 10 having an upper pipe 102, a lower pipe 103, and a stand pipe 104. The battery 15 is built into the stand pipe 104.

[0147] According to the twenty-fifth aspect, since the battery 15 is built in the upright pipe 104, the degree of freedom in designing the down pipe 103 is improved.

[0148] The 26th aspect can be realized by combining the 22nd to 24th aspects. In the 26th aspect, the electric bicycle 1 includes a battery 15 for supplying power to the motor unit 3, and a frame 10 having an upper pipe 102, a lower pipe 103, and a vertical pipe 104. The battery 15 is built into the upper pipe 102.

[0149] According to the twenty-sixth aspect, since the battery 15 is built in the upper pipe 102, the degree of freedom in designing the lower pipe 103 is improved. [Explanation of symbols]

[0150] 1. Electric bicycle 10 Frames 102 Upper Pipe 103 Lower pipe 104 Standpipe 15 Battery 191 Front sprocket 3 Motor unit 33 Torque detector 34 Input shaft rotation detector 341 Rotating Body 35 Control Board 36 Motor rotation detector 38 Terminals 4 Cases 5 Motor 51 Rotation axis 511 Pitch 52 Rotor 53 Stator 531 diameter 6 Input shaft 600 axis 8 Output Body 9 Reduction mechanism 90 Driven gear 901 diameter 91 Teeth

Claims

1. Case and A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, The motor is an inner rotor type motor. Motor unit.

2. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, A sprocket is further provided which is attached to the output body. When viewed in the axial direction, the outer periphery of the case is contained within the outer periphery of the sprocket. Motor unit.

3. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, A control board having a control unit for controlling the motor; a motor rotation detection unit that detects the number of rotations of a rotor of the motor, The motor rotation detector is provided on the control board. Motor unit.

4. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, A control board having a control unit for controlling the motor; An input shaft rotation detector that detects the rotation speed of the input shaft, The input shaft rotation detector is provided on the control board. Motor unit.

5. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, A torque detector is further provided along a surface of the input shaft to detect a torque applied to the input shaft. The output body and the input shaft are fitted together by a fitting portion formed of a spline portion or a serration portion. Motor unit.

6. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, a sprocket attached to the output body on either side in the axial direction; a torque detection unit disposed along a surface of the input shaft and detecting a torque applied to the input shaft; an input shaft rotation detector that detects the number of rotations of the input shaft; a rotor attached to the input shaft so as to rotate integrally with the input shaft to cause the input shaft rotation detector to detect the rotation speed of the input shaft, The rotating body is located on the opposite side of the torque detection unit from the side on which the sprocket is located in the axial direction. Motor unit.

7. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, a sprocket attached to the output body on either side in the axial direction; a torque detection unit disposed along a surface of the input shaft and detecting a torque applied to the input shaft; an input shaft rotation detector that detects the number of rotations of the input shaft; a rotor attached to the input shaft so as to rotate integrally with the input shaft to cause the input shaft rotation detector to detect the rotation speed of the input shaft, The rotating body is located on the side where the sprocket is located with respect to the torque detection unit in the axial direction. Motor unit.

8. A case, A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, The reduction mechanism is a motor unit having only one pair of gears that mesh with each other, The motor unit has a terminal for connection to a battery for supplying power thereto. Motor unit.

9. The diameter of the stator of the motor is 80 mm or less. A motor unit according to any one of claims 1 to 8.

10. The diameter of the stator of the motor is 70 mm or less. A motor unit according to any one of claims 1 to 8.

11. The pitch between the rotating shaft of the motor and the output body is 60 mm or less. The motor unit according to any one of claims 1 to 10.

12. The pitch between the rotating shaft of the motor and the output body is 55 mm or less. The motor unit according to any one of claims 1 to 10.

13. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, The diameter of the driven gear is 110 mm or less. A motor unit according to any one of claims 1 to 12.

14. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, The diameter of the driven gear is 95 mm or less. A motor unit according to any one of claims 1 to 12.

15. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, The number of teeth of the driving gear is 9 or less. A motor unit according to any one of claims 1 to 14.

16. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, The number of teeth of the driving gear is 4 or less. A motor unit according to any one of claims 1 to 14.

17. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, At least a portion of the driven gear is made of resin. A motor unit according to any one of claims 1 to 16.

18. The resin is a polyacetal resin.

18. A motor unit according to claim 17.

19. The reduction mechanism includes a drive gear that rotates integrally with a rotating shaft of the motor, and a driven gear that rotates integrally with the output body, The surface of the driving gear is shot peened, air blasted, plated, ground, rolled, forged, or coated. A motor unit according to any one of claims 1 to 18.

20. The pair of gears of the reduction mechanism are helical gears. A motor unit according to any one of claims 1 to 19.

21. A motor unit comprising the motor unit according to any one of claims 1 to 20. Electric bicycle.

22. An electric bicycle equipped with a motor unit, The motor unit includes: Case and A motor housed in the case; an input shaft that passes through the case in an axial direction and is arranged to be rotatable about the axis; an output body that is disposed in the case so as to be rotatable about the axis; a reduction mechanism that is housed in the case and reduces the speed of rotation of the motor and transmits the reduced speed to the output body, the reduction mechanism has only one pair of gears that mesh with each other, The rotation shaft of the motor is located above the axis and behind the axis in the traveling direction of the electric bicycle. Electric bicycle.

23. The rotating shaft of the motor is located below the axis.

22. The electric bicycle according to claim 21.

24. A battery for supplying power to the motor unit; A frame having an upper pipe, a lower pipe, and a vertical pipe; The battery is built into the standpipe. The electric bicycle according to any one of claims 21 to 23.

25. A battery for supplying power to the motor unit; A frame having an upper pipe, a lower pipe, and a vertical pipe; The battery is built into the upper pipe. The electric bicycle according to any one of claims 21 to 23.

Images