Electric power assisting unit of bicycle and electric power assisting bicycle

Abstract

An electric power assisting unit of a bicycle is miniaturized. The electric power assist unit is provided with: a plurality of sun gears which have mutually different numbers of teeth and into which a driver's pedal depression force is selectively input; a first planetary gear having a tooth surface that meshes with each of the plurality of sun gears; an electric motor that generates a driving force that assists the pedaling force of the pedal; a sun gear different from the plurality of sun gears to which the driving force from the electric motor is input; a second planetary gear that revolves and rotates integrally with the first planetary gear and meshes with a sun gear different from the plurality of sun gears; a ring gear provided so as not to rotate and meshing with the second planetary gear; a carrier that supports the first planetary gear and the second planetary gear; and a housing coupled to the carrier and transmitting at least one of the pedal pedaling force and the driving force to a driving wheel.

Description

Technical Field

[0001] The invention relates to an electric power-assisting unit of a bicycle and an electric power-assisting bicycle. Background Art

[0002] Patent Document 1 discloses a bicycle hub unit including a driving motor that generates driving force, a speed change mechanism that transmits human driving force to a hub shell (shell), and a speed reduction mechanism that transmits the driving force of the driving motor to the hub shell.

[0003] Prior art literature

[0004] Patent Document 1: (Japanese) Patent Publication No. 2013-039865 Summary of the invention

[0005] Technical problem to be solved by the invention

[0006] However, an electric assist bicycle requires more parts such as a battery and an electric assist unit than a general bicycle, and therefore, the electric assist unit needs to be further miniaturized.

[0007] However, in the hub unit of Patent Document 1, the speed change mechanism portion includes a transmission sun gear (sun gear), a transmission planetary gear (planetary gear), a transmission planetary carrier (planetary carrier), and a transmission outer ring gear (ring gear), and the driving force of human power is input to the transmission outer ring gear, and the transmission planetary carrier outputs the driving force to the hub shell. In addition, the reduction mechanism portion includes a reducer sun gear, a reducer planetary gear, and a reducer outer ring gear, and the reducer planetary gear meshes with the reducer outer ring gear, and the transmission planetary carrier holding the reducer planetary gear outputs the driving force to the hub shell. As described above, in the hub unit of Patent Document 1, since the sun gear, the planetary gear, and the outer ring gear are respectively provided in the speed change mechanism portion and the reduction mechanism portion, the structure is complicated and miniaturization is difficult.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to reduce the size of the electric assist unit.

[0009] Technical solutions for solving technical problems

[0010] According to one embodiment of the present invention, an electric power-assisting unit of a bicycle comprises: a plurality of sun gears having a different number of teeth from each other and selectively inputting a pedaling force of a rider; a first planetary gear having a tooth surface respectively meshing with the plurality of sun gears; an electric motor generating a driving force to assist the pedaling force; a sun gear different from the plurality of sun gears inputting the driving force from the electric motor; a second planetary gear which revolves and rotates integrally with the first planetary gear and meshes with a sun gear different from the plurality of sun gears, a ring gear which is arranged to be non-rotatable and meshes with the second planetary gear; a planetary carrier which supports the first planetary gear and the second planetary gear; and a housing which is connected to the planetary carrier and transmits at least one of the pedaling force and the driving force to a drive wheel.

[0011] Effects of the Invention

[0012] According to one embodiment of the present invention, a single ring gear is provided, which is set to be non-rotatable and meshes with the second planetary gear that revolves and rotates integrally with the first planetary gear. As a result, it is not necessary to provide individual ring gears in the speed reduction mechanism part that transmits the pedal force of the driver and the speed change mechanism part that transmits the driving force from the electric motor. Therefore, the electric power assist unit can be miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The following is a side view for explaining the outline of an electric assist unit for a bicycle and an electric assist bicycle according to an embodiment of the present invention.

[0014] Figure 2A It is a structural diagram of the electric power assist unit.

[0015] Figure 2B It is a structural diagram of an electric assist unit according to a modified example.

[0016] Figure 3A 1 is a collinear diagram of the electric assist unit and is a diagram showing a state in which the vehicle is switched to the first gear.

[0017] Figure 3B 2 is a collinear diagram of the electric assist unit and is a diagram showing a state in which the vehicle is switched to the second gear.

[0018] Figure 3C 3 is a collinear diagram of the electric power assist unit, and is a diagram showing a state in which the vehicle is switched to the third gear.

[0019] Figure 4 It is a cross-sectional view of the electric assist unit, and is a diagram showing a state in which the first gear is switched.

[0020] Figure 5 It is a cross-sectional view of the electric assist unit, and is a diagram showing a state in which the vehicle is switched to the second gear.

[0021] Figure 6 It is a cross-sectional view of the electric assist unit, and is a diagram showing a state in which the vehicle is switched to the third gear. DETAILED DESCRIPTION

[0022] Hereinafter, an electric assist unit for a bicycle (hereinafter simply referred to as “electric assist unit”) 100 and an electric assist bicycle (hereinafter simply referred to as “bicycle”) 1 including the electric assist unit 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0023] First, refer to Figure 1 , the overall structure of the bicycle 1 is described.

[0024] Figure 1 The diagram is a side view schematically illustrating the bicycle 1 including the electric assist unit 100 .

[0025] like Figure 1 As shown, the bicycle 1 includes: a frame 2, a front wheel 3a, a rear wheel 3b serving as a driving wheel, a handlebar 4, a seat 5, a driving sprocket 6a, a driven sprocket 6b, a chain 6c, a pair of pedals 7, crank arms 7b serving as a pair of crank parts, a crank shaft 7c, a support shaft 8, a controller 9a, a power storage unit 9b, and an electric power assist unit 100.

[0026] The bicycle 1 is driven by a rider sitting on a seat 5 and pedaling a crank arm 7b via a pedal 7. The bicycle 1 drives the rear wheel 3b by the pedaling force (driving torque) transmitted from the crank arm 7b to the crank axle 7c and the driving force (assist torque) of the electric assist unit 100 of a magnitude corresponding to the pedaling force.

[0027] The vehicle frame 2 is a so-called diamond-shaped vehicle frame having a substantially parallelogram shape in side view. A front wheel 3a and a rear wheel 3b are rotatably mounted on the vehicle frame 2. The vehicle frame 2 has a front fork 2a that supports the front wheel 3a.

[0028] The front wheel 3a is turned left and right by the front fork 2a being rotated by the operator's operation of the handlebars 4.

[0029] The rear wheel 3b rotates around the support shaft 8. The driven sprocket 6b and the electric assist unit 100 are mounted on the rear wheel 3b.

[0030] The driving torque is transmitted to the driven sprocket 6b via the chain 6c suspended between the driven sprocket 6b and the driving sprocket 6a to which the driving force from the crank arm 7b is input.

[0031] The electric power assist unit 100 generates an assist torque to assist the driver's pedal force. Figure 2A as well as Figure 2B Explain in detail.

[0032] The pedal 7 is a member for the driver to input driving torque, and is connected to a crankshaft 7c via a crank arm 7b.

[0033] The support shaft 8 is mounted on the vehicle frame 2. The support shaft 8 is provided so as to be non-rotatable relative to the vehicle frame 2.

[0034] The controller 9a is composed of a microcomputer having a CPU, a RAM, a ROM, an input / output interface, etc. The controller 9a can also be composed of a plurality of microcomputers. The controller 9a performs various processes by reading and executing the program stored in the ROM through the CPU. Specifically, the controller 9a calculates the assist torque based on an electrical signal corresponding to the magnitude of the pedal force input from a torque sensor (omitted in the figure) described later, and outputs a command signal to cause the electric motor 70 to generate the assist torque.

[0035] The power storage unit 9 b is a rechargeable and dischargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The power storage unit 9 b is provided so as to be detachable from the vehicle frame 2 .

[0036] Next, refer to Figure 2A as well as Figure 2B The structure of the electric assist unit 100 will be described.

[0037] Figure 2A is a structural diagram of the electric power assist unit 100 . Figure 2B 1 is a diagram showing a configuration of an electric assist unit 100 according to a modified example.

[0038] like Figure 2A As shown, the electric power assist unit 100 includes a housing unit 10, a planetary gear mechanism 20, a torque sensor (not shown), an electric motor 70, a plurality of (three in this case) one-way clutches 81, 82, 83, and a power input member 90. The electric power assist unit 100 can switch the gear speed between the first gear (lowest gear), the second gear, and the third gear (highest gear).

[0039] The housing unit 10 includes a stationary housing 11 , a rotating housing 12 as a housing, a support member 13 , and a motor support portion 14 .

[0040] The fixed housing 11 is fixed to the support shaft 8 . The fixed housing 11 does not rotate relative to the support shaft 8 .

[0041] The rotating housing 12 is provided separately from the fixed housing 11. The rotating housing 12 supports the rear wheel 3b rotatably relative to the support shaft 8. The rotating housing 12 is provided integrally with the planetary carrier 50 described later of the planetary gear mechanism 20. The rotating housing 12 rotates together with the planetary carrier 50 relative to the support shaft 8. The rotating housing 12 is connected to the planetary carrier 50 and transmits at least one of the pedal force and the driving force to the rear wheel 3b. The rotating housing 12 rotates together with the rear wheel 3b relative to the fixed housing 11 with the support shaft 8 as the center. The rear wheel 3b is mounted on the outer periphery of the rotating housing 12 through spokes (not shown).

[0042] The support member 13 rotates together with the rotating case 12 (planetary carrier 50 ) and supports planetary gears 40 and 43 of the planetary gear mechanism 20 to be described later on the rotating case 12 . The support member 13 supports the planetary gears 40 and 43 of the planetary gear mechanism 20 to be described later on the rotating case 12 .

[0043] As described above, since the support member 13 supports the planetary gear 40 and the planetary gear 43 between the planetary gears 40 and 43 on the rotating housing 12, the planetary gears 40 and the planetary gears 43 are supported by the rotating housing 12 in a double manner. Therefore, compared with the case where the planetary gears 40 and the planetary gears 43 are supported by the rotating housing 12 in a cantilever manner from the end, the planetary gears 40 and the planetary gears 43 can be stably supported on the rotating housing 12. In addition, compared with the planetary gears 43 formed to have a large diameter in order to reduce the rotation of the electric motor 70, the support portion of the planetary carrier 50 side of the support member 13 is arranged on the inner peripheral surface side of the rotating housing 12 of the support member 13, so that the radial length of the planetary gears of the support member 13 can be shortened, and the support member 13 can be miniaturized.

[0044] It should be noted that if Figure 2B As shown, the planetary gears 40 and 43 may be arranged in sequence along the axial direction, and the support member 13 may support the position farthest from the inner circumference of the rotating housing 12. That is, the planetary gears 40 and 43 may be double-supported at both ends by the rotating housing 12 and the support member 13.

[0045] The motor support portion 14 is formed as a part of the fixed housing 11. The motor support portion 14 non-rotatably supports a stator 71 described later of the electric motor 70. The motor support portion 14 non-rotatably supports a ring gear 60 described later of the planetary gear mechanism 20.

[0046] The planetary gear mechanism 20 includes sun gears 31 and 32 as a plurality of sun gears, a sun gear 33 as a sun gear different from the plurality of sun gears, a planetary gear 40 as a first planetary gear, a planetary gear 43 as a second planetary gear, a carrier 50 , and a ring gear 60 .

[0047] The sun gears 31 and 32 have different numbers of teeth. The driver's pedal force is selectively input to the sun gears 31 and 32 .

[0048] The sun gear 31 is disposed on the outer periphery of the power input member 90. The sun gear 31 is disposed so as to sandwich the sun gear 32 between the sun gear 31 and the inner peripheral surface of the rotating housing 12. When the speed is switched to the first speed with the largest reduction ratio, the sun gear 31 transmits power to the tooth surface 41 of the planetary gear 40 described later.

[0049] The sun gear 32 is disposed on the outer periphery of the power input member 90. The sun gear 32 is disposed in a manner that it is aligned with the sun gear 31 in the axial direction and faces the inner peripheral surface of the rotating housing 12. The sun gear 32 has a larger outer diameter than the sun gear 31. When the speed gear is switched to the second gear having a smaller reduction ratio than the first gear, the sun gear 32 transmits power to the tooth surface 42 of the planetary gear 40 described later.

[0050] The sun gear 33 is provided separately from the sun gears 31 and 32. The sun gear 33 is provided on the outer periphery of the support shaft 8. The driving force from the electric motor 70 is input to the sun gear 33. The sun gear 33 transmits the assist torque of the electric motor 70 to the planetary gear 43.

[0051] The planetary gear 40 is supported by the planetary carrier 50. The planetary gear 40 rotates around the rotation axis A and revolves around the outer circumference of the sun gear 31. The planetary gear 40 meshes with the sun gears 31 and 32, respectively, and has a plurality of tooth surfaces 41 and 42 that are coaxially arranged and rotate integrally. That is, the plurality of tooth surfaces 41 and 42 are coaxially arranged with each other to constitute the planetary gear 40.

[0052] The tooth surface 41 is provided so as to sandwich the tooth surface 42 between the tooth surface 41 and the inner peripheral surface of the rotating housing 12. The tooth surface 41 meshes with the sun gear 31. When the speed is switched to the first speed, the power from the sun gear 31 is transmitted to the tooth surface 41.

[0053] The tooth surface 42 is arranged in parallel with the tooth surface 41 in the axial direction and faces the inner peripheral surface of the rotating housing 12. The tooth surface 42 is coaxially arranged with the tooth surface 41 and rotates integrally. The tooth surface 42 meshes with the sun gear 32. The tooth surface 42 is formed to have a smaller outer diameter than the tooth surface 41. When the speed gear is switched to the second gear, the power from the sun gear 32 is transmitted to the tooth surface 42.

[0054] The planetary gear 43 is provided separately from the planetary gear 40 and supported by the planetary carrier 50. The planetary gear 43 is provided in a manner that the support portion of the support member 13 is sandwiched between the planetary gear 40. The planetary gear 43 rotates around the rotation axis A and revolves around the outer periphery of the sun gear 33. The planetary gear 43 is provided coaxially with the planetary gear 40 and revolves and rotates integrally. The planetary gear 43 has a tooth surface 44 meshing with the sun gear 33 and a tooth surface 45 meshing with the ring gear 60.

[0055] The tooth surface 44 is formed to have the largest outer diameter among the tooth surfaces 41 , 42 , 44 , and 45 . The assist torque from the electric motor 70 is transmitted to the tooth surface 44 via the sun gear 33 regardless of the gear speed.

[0056] The tooth surface 45 is arranged axially with the tooth surface 44 and is disposed at a position farther from the inner peripheral surface of the planetary gear 40 side of the rotating housing 12 than the tooth surface 44. The tooth surface 45 is disposed coaxially with the tooth surface 44 and rotates integrally. The tooth surface 45 is formed to have a larger outer diameter than the planetary gear 40 and a smaller outer diameter than the tooth surface 44. The tooth surface 45 meshes with the inner periphery of the ring gear 60.

[0057] In this way, since the outer diameter of the tooth surface 45 meshing with the inner periphery of the ring gear 60 is smaller than the outer diameter of the tooth surface 44, it is possible to suppress the radial expansion of the rotating housing 12, and it is possible to increase the reduction ratio of the electric motor 70 and increase the assist torque. Instead, it is also possible to configure the ring gear 60 to mesh with the outer periphery of the tooth surface 44 without providing the tooth surface 45. In this case, since it is not necessary to provide the tooth surface 45, the axial length of the electric assist unit 100 can be reduced.

[0058] The planetary carrier 50 is provided integrally with the rotating housing 12 and supports one axial end of the planetary gears 40 and 43. A portion away from one axial end of the planetary gears 40 and 43 is supported by the support member 13. That is, the planetary gears 40 and 43 are supported by the planetary carrier 50 and the support member 13 at two locations. The planetary carrier 50 supports the planetary gears 40 and 43 so that they can rotate (rotate) around the rotation axis A. The planetary carrier 50 rotates together with the rotating housing 12 around the support shaft 8 as the planetary gears 40 and 43 revolve.

[0059] In this way, the pedal force of the driver is transmitted from the inner periphery to the outer periphery in sequence to the sun gears 31 and 32, the planetary gears 40, the planetary carrier 50, the rotating housing 12, and the rear wheel 3b. Therefore, compared with the case where the driving force is input from the ring gear outside the planetary carrier as a speed change mechanism and the driving force is output to the rotating housing outside the ring gear, the input path and output path of the driving force can be made into a simple structure. Therefore, the electric power assist unit 100 can be miniaturized.

[0060] In addition, by setting the driving force input gear for inputting driving force from the electric motor 70 as the sun gear 33, the driving force from the electric motor 70 is transmitted to the sun gear 33, the planetary gear 43, the planetary carrier 50, the rotating housing 12, and the rear wheel 3b in sequence from the inner periphery to the outer periphery in the same manner as the input of the pedal force. Therefore, compared with the case where the driving force is input from the ring gear outside the planetary carrier as a speed change mechanism and the driving force is output to the rotating housing outside the ring gear, the input path and output path of the driving force can be made into a simple structure. Therefore, the electric power assist unit 100 can be miniaturized.

[0061] In addition, the electric booster unit 100 is provided with a single ring gear 60 which is provided so as not to rotate and meshes with the planetary gear 43 which revolves and rotates integrally with the planetary gear 40. Therefore, it is not necessary to provide individual ring gears in the speed change mechanism part which transmits the pedal force of the driver and the speed reduction mechanism part which transmits the driving force from the electric motor 70. Therefore, the electric booster unit 100 can be miniaturized.

[0062] The ring gear 60 is non-rotatably supported on the support shaft 8. The ring gear 60 meshes only with the tooth surface 45 of the planetary gear 43, but the ring gear 60 is a common ring gear for the planetary gears 40, 43 because the planetary gears 40, 43 are coaxially arranged and revolve and rotate integrally.

[0063] As described above, since the ring gear 60 is commonly used in the input path of the pedal force of the driver and the input path of the driving force of the electric motor 70 , the number of components can be reduced.

[0064] The electric motor 70 assists the driving force according to the pedaling force of the driver. The electric motor 70 is driven by a command from the controller 9a. The electric motor 70 generates assist torque using the electric power supplied from the power storage unit 9b.

[0065] The torque sensor detects driving torque generated by the driver stepping on the crank arm 7b through the pedal 7 and transmitted to the crank shaft 7c. The torque sensor is, for example, a non-contact torque sensor that detects torque based on the torsion of the crank shaft 7c measured by magnetism.

[0066] The one-way clutch 81 is provided between the inner periphery of the sun gear 31 and the outer periphery of the power input component 90. The one-way clutch 81 switches between a state in which the pedal force of the driver is transmitted to the sun gear 31 through the power input component 90 and a state in which the rotation of the sun gear 31 is not transmitted to the pedal 7. Thus, the one-way clutch 81 transmits the pedal force of the driver to the sun gear 31 through the power input component 90. The one-way clutch 81 does not transmit the rotation of the sun gear 31 to the pedal 7.

[0067] The one-way clutch 82 is provided between the inner periphery of the sun gear 32 and the outer periphery of the power input component 90. The one-way clutch 82 switches between a state in which the pedal force of the driver is transmitted to the sun gear 32 through the power input component 90 and a state in which the rotation of the sun gear 32 is not transmitted to the pedal 7. Thus, the one-way clutch 82 transmits the pedal force of the driver to the sun gear 32 through the power input component 90. The one-way clutch 82 does not transmit the rotation of the sun gear 32 to the pedal 7.

[0068] The one-way clutch 83 is provided between the inner periphery of the rotating housing 12 and the outer periphery of the power input member 90. The one-way clutch 83 switches between a state in which the pedal force of the driver is transmitted to the rotating housing 12 through the power input member 90 and a state in which the rotation of the rotating housing 12 is not transmitted to the pedal 7. The one-way clutch 83 transmits the pedal force of the driver to the rotating housing 12 via the power input member 90.

[0069] As described above, since a plurality of one-way clutches 81, 82, 83 are provided, even if a pedal force is input from two adjacent ones of the one-way clutches 81, 82, 82 during a gear shift, the pedal force is not transmitted to the one with a higher rotation speed among the sun gears 31, 32 and the rotating housing 12. Therefore, the gear shift can be smoothly changed.

[0070] The power input component 90 is provided on the inner periphery of the driven sprocket 6b to which the pedal force is input. The power input component 9 is a cylindrical component rotatably provided on the outer periphery of the support shaft 8. The power input component 90 selectively transmits the driving torque input from the driven sprocket 6b to any one of the sun gears 31, 32 and the rotating housing 12 through any one of the one-way clutches 81, 82, 83.

[0071] Next, refer to Figure 3A to Figure 3C , each gear stage of the electric power assist unit 100 will be described.

[0072] Figure 3A 1 is a collinear diagram of the electric assist unit 100 and is a diagram showing a state in which the first gear is switched. Figure 3B 2 is a collinear diagram of the electric assist unit 100 and shows a state in which the gear is switched to the second gear. Figure 3C 2 is a collinear diagram of the electric assist unit 100 and shows a state in which the gear is switched to the third gear.

[0073] like Figure 3AAs shown, in the state where the speed gear is switched to the lowest gear, i.e., the first gear, the driving torque input from the driven sprocket 6b via the power input member 90 is transmitted to the sun gear 31 through the one-way clutch 81. Since the sun gear 31 meshes with the tooth surface 41 of the planetary gear 40, the driving force is transmitted from the sun gear 31 to the planetary gear 40, and the revolution of the planetary gear 40 is transmitted from the planetary carrier 50 to the rotating housing 12. As a result, the pedal force of the driver is decelerated and transmitted to the rear wheel 3b.

[0074] At this time, because the outer diameter of the sun gear 31 is smaller than that of the sun gear 32, and the outer diameter of the tooth surface 41 in the planetary gear 40 is larger than that of the tooth surface 42 (the number of teeth formed on the tooth surface 41 is greater than the number of teeth formed on the tooth surface 42), the driver's pedal force is transmitted to the rear wheel 3b with the maximum reduction ratio.

[0075] like Figure 3B As shown, in the state where the speed gear is switched to the second gear, the driving torque input from the driven sprocket 6b via the power input member 90 is transmitted to the sun gear 32 through the one-way clutch 82. Since the sun gear 32 is meshed with the tooth surface 42 of the planetary gear 40, the driving force is transmitted from the sun gear 32 to the planetary gear 40, and the revolution of the planetary gear 40 is transmitted from the planetary carrier 50 to the rotating housing 12. As a result, the pedal force of the driver is decelerated and transmitted to the rear wheel 3b.

[0076] At this time, because the outer diameter of the sun gear 32 is larger than that of the sun gear 31, and the outer diameter of the tooth surface 42 in the planetary gear 40 is smaller than that of the tooth surface 41 (the number of teeth formed on the tooth surface 42 is less than the number of teeth formed on the tooth surface 41), the driver's pedal force is transmitted to the rear wheel 3b with a smaller reduction ratio compared to the case where the gear shift gear is the first gear.

[0077] like Figure 3C As shown in the figure, when the gear is switched to the highest gear, i.e., the third gear, the driving torque input from the driven sprocket 6b via the power input member 90 is directly transmitted to the rotating housing 12 through the one-way clutch 83. At this time, the driven sprocket 6b, the power input member 90, and the rotating housing 12 rotate integrally. As a result, the pedal force of the driver is directly transmitted to the rear wheel 3b without deceleration.

[0078] Next, refer to Figure 4~Figure 6 , the specific structure of the electric power assist unit 100 is described. It should be noted that, because the structure of the electric power assist unit 100 has been referred to Figure 2A as well as Figure 2B The above description has been given, so repeated description will be omitted as appropriate.

[0079] Figure 4 1 is a cross-sectional view of the electric assist unit 100 , showing a state in which the first gear is switched. Figure 51 is a cross-sectional view of the electric assist unit 100 , showing a state in which the gear is switched to the second gear. Figure 6 1 is a cross-sectional view of the electric assist unit 100 , showing a state in which the gear is switched to the third gear.

[0080] The electric assist unit 100 includes a housing unit 10 , a planetary gear mechanism 20 , a torque sensor, an electric motor 70 , a plurality of one-way clutches 81 , 82 , and 83 , a power input member 90 , a speed change shaft 92 , and a slide engagement member 94 .

[0081] The housing unit 10 includes a stationary housing 11 , a rotating housing 12 , a support member 13 , and a motor support portion 14 .

[0082] The stationary housing 11 is formed in a substantially cup shape with substantially the entire surface of one axial surface open. The stationary housing 11 is attached to the support shaft 8 and rotates integrally with the support shaft 8. The stationary housing 11 accommodates the electric motor 70, the sun gear 33, and the ring gear 60.

[0083] The rotating housing 12 includes a first housing 12 a , a second housing 12 b , and a plurality of bolts 12 c as fastening members.

[0084] The first housing 12a is formed into a cup shape with the substantially entire surface of the other axial surface open. The first housing 12a is rotatably supported on the outer periphery of the power input member 90 via a bearing 16. The first housing 12a accommodates the sun gears 31, 32, the planetary gears 40, 43, and the one-way clutches 81, 82, 83. The first housing 12a is provided in a manner that the fixed housing 11 and the opening portion are opposed. A flange 17 for connecting the spokes is provided on the outer periphery of the first housing 12a in a manner that protrudes toward the outer periphery.

[0085] The second housing 12b is formed into a cup shape with substantially the entire surface of one axial side open. The second housing 12b is spaced apart from the outer surface of the fixed housing 11 in a manner covering the outer side of the fixed housing 11. The second housing 12b is rotatably supported on the outer periphery of the fixed housing 11 by a bearing 15. The second housing 12b is provided in a manner opposing the first housing 12a and the opening portion, and is fastened to the first housing 12a by a bolt 12c. The opening portion of the second housing 12b opens in the same direction as the opening portion of the fixed housing 11. On the outer periphery of the second housing 12b, another flange 17 for connecting the spokes is provided in a manner protruding toward the outer periphery.

[0086] Thus, the sun gears 31, 32, planetary gears 40, 43 and one-way clutches 81, 82, 83 are accommodated in the first housing 12a. When the electric motor 70, the sun gear 33 and the ring gear 60 are accommodated in the fixed housing 11, the electric power assist unit 100 can be assembled simply by placing the openings of the first housing 12a and the fixed housing 11 opposite to each other, installing the second housing 12b and fastening it with the first housing 12a and the bolts 12c.

[0087] The substantially entire surface of one axial side of the support member 13 is open, and the rotation center portion of the other side and the vicinity thereof are formed into a substantially cup shape that is open so that the support shaft 8 can be inserted. The support member 13 is formed to have an outer diameter smaller than that of the first housing 12a. The support member 13 is mounted on the inner wall surface extending in the radial direction of the first housing 12a in such a manner that one open surface faces the inner wall surface extending in the radial direction of the first housing 12a. The support member 13 supports the planetary gears 40, 43 through the bearing 13a so that the planetary gears 40, 43 can rotate around the rotation axis A. The support member 13 rotates together with the planetary gears 40, 43 around the support shaft 8 as the planetary gears 40, 43 revolve.

[0088] The planetary carrier 50 is provided integrally with the rotating housing 12. In other words, the planetary carrier 50 constitutes a part of the rotating housing 12. The planetary carrier 50 supports the planetary gears 40, 43 via the bearings 50a so that the planetary gears 40, 43 can rotate about the rotation axis A. The planetary carrier 50 rotates together with the planetary gears 40, 43 about the support shaft 8 as the planetary gears 40, 43 revolve.

[0089] The electric motor 70 includes a stator 71 and a rotor 72. The stator 71 is supported by the motor support portion 14 so as not to rotate. The rotor 72 is provided on the inner circumference of the stator 71 and rotates relative to the stator 71. The sun gear 33 is attached to the rotor 72. The rotor 72 rotates together with the sun gear 33.

[0090] The power input member 90 is rotatably supported on the outer periphery of the support shaft 8 via a bearing 91. The power input member 90 has a spline 90a as a first engagement portion and a spline 90b as a second engagement portion.

[0091] The spline 90a is formed on the outer periphery of the large diameter portion formed to have a large diameter, and engages with the spline formed on the inner peripheral surface of the driven sprocket 6b.

[0092] The spline 90b is formed on the outer periphery of the small diameter portion, which is smaller in diameter than the spline 90a and is formed at an axially offset position, and the spline 90b engages with the spline 94a of the sliding engagement member 94. Regardless of the axial position of the sliding engagement member 94, the spline 90b always engages with the spline 94a.

[0093] The speed change shaft 92 is slidable in the axial direction inside the support shaft 8 , and the axial engagement position with the slide engagement member 94 switches which inner ring 81 a , 82 a , 83 a the slide engagement member 94 rotates with.

[0094] Thus, the shift speed can be changed by simply changing the axial position of the shift shaft 92 based on the driver's operation. Therefore, for example, the shift speed can be changed by the driver's operation of a lever or the like, similar to the shifting of a normal bicycle.

[0095] The connection member 93 is provided at a right angle to the central axis of the speed change shaft 92 and axially engages with the speed change shaft 92. The connection member 93 connects the speed change shaft 92 and the slide engagement member 94 and allows the speed change shaft 92 and the slide engagement member 94 to move integrally in the axial direction.

[0096] The slide engagement member 94 is axially slidably provided relative to the power input member 90 and is engaged with the power input member 90 so as to rotate together with the power input member 90. The slide engagement member 94 is engaged with any one of the inner rings 81a, 82a, 83a of the plurality of one-way clutches 81, 82, 83 so as to rotate together.

[0097] Specifically, the sliding engagement member 94 is a member composed of two coaxial cylindrical portions. The inner circumference of the small diameter cylindrical portion located on the inner circumference side of the sliding engagement member 94 engages with the connecting member 93. The inner circumference of the large diameter cylindrical portion located on the outer circumference side of the sliding engagement member 94 is formed with a spline 94a as a third engagement portion, and the outer circumference is formed with a spline 94b as a fourth engagement portion.

[0098] The spline 94a is engaged with the spline 90b of the power input member 90. The spline 94b is selectively engaged with any one of the inner rings 81a, 82a, 83a of the one-way clutches 81, 82, 83.

[0099] Thus, the pedal force input from the power input member 90 can be transmitted to any one of the one-way clutches 81 , 82 , and 83 simply by sliding the slide engagement member 94 in the axial direction.

[0100] Next, each gear stage of the electric booster unit 100 will be described.

[0101] exist Figure 4In the state shown, the gear of the electric power assist unit 100 is shifted to the first gear. At this time, the driving torque input from the driven sprocket 6b via the power input component 90 is transmitted to the sun gear 31 through the sliding engagement component 94 and the one-way clutch 81. Because the sun gear 31 is meshed with the tooth surface 41 of the planetary gear 40, the driving force is transmitted from the sun gear 31 to the planetary gear 40, and the revolution of the planetary gear 40 is transmitted from the planetary carrier 50 to the rotating housing 12. As a result, the rotation of the driven sprocket 6b rotated by the pedal force of the driver is decelerated and transmitted to the rear wheel 3b. When the speed change shaft 92 slides in the direction of exiting from the housing unit 10 based on the driver's operation, the state is switched from this state to Figure 5 Status shown.

[0102] exist Figure 5 In the state shown, the gear of the electric power assist unit 100 is shifted to the second gear. At this time, the driving torque input from the driven sprocket 6b through the power input component 90 is transmitted to the sun gear 32 through the sliding engagement component 94 and the one-way clutch 82. Because the sun gear 32 is meshed with the tooth surface 42 of the planetary gear 40, the driving force is transmitted from the sun gear 32 to the planetary gear 40, and the revolution of the planetary gear 40 is transmitted from the planetary carrier 50 to the rotating housing 12. As a result, the rotation of the driven sprocket 6b rotated by the pedal force of the driver is decelerated and transmitted to the rear wheel 3b. When the speed change shaft 92 further slides in the direction of exiting from the housing unit 10 based on the driver's operation, the state is switched from this state to Figure 6 Status shown.

[0103] exist Figure 6 In the state shown, the gear shift of the electric power assist unit 100 is shifted to the third gear. At this time, the driving torque input from the driven sprocket 6b via the power input component 90 is directly transmitted to the rotating housing 12 via the sliding engagement component 94 and the one-way clutch 83. At this time, the driven sprocket 6b, the power input component 90 and the rotating housing 12 rotate integrally. As a result, the rotation of the driven sprocket 6b rotated by the pedal force of the driver is directly transmitted to the rear wheel 3b without deceleration.

[0104] As described above, in the electric power assist unit 100, the input and output are configured to be equal in speed at the third speed, and the first speed and the second speed have a speed ratio on the deceleration side. Thus, when the electric motor 70 transmits the assist torque to the drive wheel, i.e., the rear wheel 3b, in the state of switching to the third speed, which is the highest gear with the highest frequency of use, the pedal force of the driver is directly transmitted to the rotating shell 12 without passing through the various structures of the planetary gear mechanism 20. Therefore, the load applied to the various structures of the planetary gear mechanism 20 of the electric power assist unit 100 can be avoided, and the durability of the electric power assist unit 100 can be improved.

[0105] The above configuration and operational effects of the present embodiment will be summarized and described.

[0106] (1)(7) The electric assist unit 100 of the bicycle 1 includes: a plurality of sun gears 31, 32 having different numbers of teeth from each other and selectively inputting the pedal force of the rider; a planetary gear 40 having tooth surfaces 41, 42 respectively meshing with the plurality of sun gears 31, 32; an electric motor 70 generating a driving force to assist the pedal force; a sun gear 33 different from the plurality of sun gears 31, 32 to which the driving force from the electric motor 70 is input; a planetary gear 43 revolving and rotating integrally with the planetary gear 40 and meshing with a sun gear 33 different from the plurality of sun gears 31, 32; a ring gear 60 arranged to be non-rotatable and meshing with the planetary gear 43; a planetary carrier 50 supporting the planetary gears 40 and the planetary gears 43; and a rotating housing 12 connected to the planetary carrier 50 and transmitting at least one of the pedal force and the driving force to the rear wheel 3b.

[0107] According to this structure, the electric booster unit 100 is provided with a single ring gear 60 which is set to be non-rotatable and meshes with the planetary gear 43 which revolves and rotates integrally with the planetary gear 40. Therefore, it is not necessary to provide ring gears separately in the speed change mechanism part which transmits the pedal force of the driver and the speed reduction mechanism part which transmits the driving force from the electric motor 70. Therefore, the electric booster unit 100 can be miniaturized.

[0108] In addition, the pedal force of the driver is transmitted from the inner periphery to the outer periphery in sequence to the sun gears 31 and 32, the planetary gears 40, the planetary carrier 50, the rotating housing 12, and the rear wheel 3b. Therefore, compared with the case where the driving force is input from the ring gear outside the planetary carrier as a speed change mechanism and the driving force is output to the rotating housing outside the ring gear, the input path and output path of the driving force can be made into a simple structure. Therefore, the electric power assist unit 100 can be miniaturized.

[0109] (2) The rotating case 12 supports the rear wheel 3 b rotatably with respect to the support shaft 8 , and rotates together with the planetary carrier 50 with respect to the support shaft 8 .

[0110] According to this structure, the pedal force of the driver is input to the sun gear 31, 32 or the rotating housing 12 of the electric power assist unit 100 via the driving sprocket 6a and the driven sprocket 6b. When the number of teeth of the driven sprocket 6b is smaller than the number of teeth of the driving sprocket 6a, the driving force transmitted from the driving sprocket 6a to the driven sprocket 6b is increased, and the torque input to the sun gear 31, 32 or the rotating housing 12 is reduced accordingly. Therefore, the endurance of each structural component of the electric power assist unit 100 can be reduced, and the enlargement of the electric power assist unit 100 can be suppressed.

[0111] (3) The electric assist unit 100 further includes a plurality of one-way clutches 81 , 82 that switch between a state in which the pedal force of the driver is transmitted to the plurality of sun gears 31 , 32 and a state in which the rotation of the plurality of sun gears 31 , 32 is not transmitted to the pedal 7 .

[0112] According to this configuration, since the one-way clutches 81 and 82 are provided, even if pedal force is input from both the one-way clutches 81 and 82 during the gear shift, the pedal force is not transmitted to the sun gear 31 or 32 with a higher rotation speed. Therefore, the gear stage can be changed smoothly.

[0113] (4) In addition, the electric assist unit 100 further comprises: a power input component 90, which is arranged on the inner periphery of the driven sprocket 6b that inputs the pedal force; and a sliding engagement component 94, which is arranged to slide freely in the axial direction relative to the power input component 90, and is engaged with the power input component 90 in a manner that rotates together with the power input component 90, and is engaged in a manner that rotates together with any one of the inner rings 81a, 82a, 83a of the multiple one-way clutches 81, 82, 83.

[0114] According to this configuration, the pedal force input from the power input member 90 can be transmitted to any one of the one-way clutches 81 , 82 , and 83 simply by sliding the slide engagement member 94 in the axial direction.

[0115] (5) The electric booster unit 100 further includes a speed change shaft 92 that is axially slidable inside the support shaft 8 and switches which inner ring 81 a , 82 a , 83 a the slide engagement member 94 rotates with, depending on the axial engagement position with the slide engagement member 94 .

[0116] According to this structure, the shift speed can be changed by simply changing the axial position of the shift shaft 92 based on the driver's operation. Therefore, for example, the shift speed can be changed by the driver's operation of the lever at hand, etc., similar to the shifting of a normal bicycle.

[0117] (6) The electric booster unit 100 further includes the support member 13 that supports the planetary gears 40 and 43 with respect to the rotating housing 12 .

[0118] According to this structure, since the support member 13 supports the planetary gear 40 and the planetary gear 43 between the rotating housing 12, the planetary gear 40 and the planetary gear 43 are cantilever-supported on the rotating housing 12. Therefore, compared with the case where the planetary gear 40 and the planetary gear 43 are supported from both ends, the axial length of the planetary gear 40 and the planetary gear 43 can be reduced.

[0119] As mentioned above, although the embodiment of the present invention is described, the above embodiment is only one application example of the present invention, and it is not intended that the technical scope of the present invention is limited to the specific structure of the above embodiment.

[0120] For example, in the above-mentioned embodiment, the electric power assist unit 100 and the driven sprocket 6b are installed together on the rear wheel 3b. However, the electric power assist unit 100 can also be installed together with the driving sprocket 6a on the crankshaft 7c. In this case, it can also be configured that the driver steps on the crank arm 7b via the pedal 7, and the pedal force (driving torque) transmitted from the crank arm 7b to the crankshaft 7c is input to the sun gear 31, 32 or the rotating housing 12. In addition, it can also be a structure as follows: the output of the electric power assist unit 100 is transmitted to the driving sprocket 6a through the rotating housing 12, and is transmitted to the driven sprocket 6b through the chain 6c suspended between the driven sprocket 6b and the driving sprocket 6a, and the rear wheel 3b is rotated.

[0121] In the above embodiment, the rotor 72 is a so-called inner rotor provided on the inner periphery of the stator 71. Instead of this configuration, a so-called outer rotor may be used in which the stator is provided on the inner periphery and the rotor rotates on the outer periphery of the stator.

[0122] In addition, in the above-mentioned embodiment, a plurality of one-way clutches 81 and 82 are provided, and the plurality of one-way clutches 81 and 82 switch between a state in which the pedal force of the driver is transmitted to the plurality of sun gears 31 and 32 respectively, and a state in which the rotation of the sun gears 31 and 32 is not transmitted to the pedal 7. Instead of this configuration, only a plurality of clutches may be provided, and the plurality of clutches switch between a state in which the pedal force of the driver is transmitted to the plurality of sun gears 31 and 32 respectively, and a state in which the rotation of the sun gears 31 and 32 is not transmitted to the pedal 7.

[0123] In addition, in the above-mentioned embodiment, the structure is provided with: the power input member 90, which is provided on the inner periphery of the driven sprocket 6b that inputs the pedal force; and the sliding engagement member 94, which is provided to slide freely in the axial direction relative to the power input member 90, and is engaged with the power input member 90 in a manner of rotating together with the power input member 90, and is engaged in a manner of rotating together with any one of the inner rings 81a, 82a, 83a of the plurality of one-way clutches 81, 82, 83. Instead of this structure, it is also possible to have a structure that includes a rotation engagement member that is engaged in a manner of rotating together with any one of the inner rings 81a, 82a, 83a of the plurality of one-way clutches 81, 82, 83 by rotating relative to the shaft.

[0124] In addition, in the above-mentioned embodiment, the support member 13 is further provided to support the planetary gear 40 and the planetary gear 43 between the rotating housing 12, and the planetary gears 40 and 43 are arranged in sequence in the axial direction, and the support member 13 does not support the position farthest from the inner peripheral surface of the rotating housing 12 on the side of the planetary gear 40. Instead of this configuration, it is also possible to have a configuration in which the support member 13 is not provided and the cantilever of the planetary carrier 50 is supported only on the wall portion of the rotating housing 12.

[0125] Description of Reference Numerals

[0126] 100: electric power assist unit; 1: bicycle; 3b: rear wheel (driving wheel); 6b: driven sprocket; 7: pedal; 8: supporting shaft; 12: rotating housing (housing); 13: supporting member; 31, 32: sun gear; 33: sun gear; 40: planetary gear (first planetary gear); 41, 42: tooth surface; 43: planetary gear (second planetary gear); 44, 45: tooth surface; 50: planetary carrier; 60: ring gear; 70: electric motor; 81, 82, 83: one-way clutch; 81a, 82a, 83a: inner ring; 90: power input member; 92: speed change shaft; 94: sliding engagement member.

Claims

1. An electric power assist unit for a bicycle, characterized in that: have: a plurality of sun gears having mutually different numbers of teeth and selectively inputting a driver's pedal force; A first planetary gear having tooth surfaces respectively meshing with the plurality of sun gears; An electric motor that generates a driving force to assist the pedaling force; a sun gear different from the plurality of sun gears to which the driving force from the electric motor is input; a second planetary gear that orbits and rotates integrally with the first planetary gear and meshes with a sun gear different from the plurality of sun gears; A ring gear, which is arranged to be non-rotatable and meshes with the second planetary gears; a planet carrier, which supports the first planetary gear and the second planetary gear; A housing is connected to the planetary carrier and transmits at least one of the pedal force and the driving force to a driving wheel.

2. The electric power assist unit for a bicycle according to claim 1, characterized in that: The housing supports the drive wheel rotatably with respect to the support shaft, and rotates together with the planetary carrier with respect to the support shaft.

3. The electric power assist unit for a bicycle according to claim 2, characterized in that: Also available: A plurality of one-way clutches are configured to switch between a state in which the pedal force of the driver is transmitted to the plurality of sun gears respectively and a state in which the rotation of the plurality of sun gears is not transmitted to the pedal.

4. The electric power assist unit for a bicycle according to claim 3, characterized in that: Also available: A power input component, which is arranged on the inner periphery of the driven sprocket for inputting the pedal force; The sliding engagement member is axially slidably provided relative to the power input member, is engaged with the power input member so as to rotate together with the power input member, and is engaged with any one of the inner rings of the plurality of one-way clutches so as to rotate together with the power input member.

5. The electric power assist unit for a bicycle according to claim 4, characterized in that: Also available: The speed change shaft is axially slidable inside the support shaft, and switches which inner ring the sliding engagement member rotates with according to an axial engagement position with the sliding engagement member.

6. The electric power assist unit for a bicycle according to any one of claims 1 to 5, characterized in that: Also available: A support member supports the first planetary gear and the second planetary gear between the first planetary gear and the second planetary gear on the housing.

7. An electric power-assisted bicycle, characterized in that: have: a plurality of sun gears having mutually different numbers of teeth and selectively inputting a driver's pedal force; A first planetary gear having tooth surfaces respectively meshing with the plurality of sun gears; An electric motor that generates a driving force to assist the pedaling force; a sun gear different from the plurality of sun gears to which the driving force from the electric motor is input; a second planetary gear that orbits and rotates integrally with the first planetary gear and meshes with a sun gear different from the plurality of sun gears; A ring gear, which is arranged to be non-rotatable and meshes with the second planetary gears; a planet carrier, which supports the first planetary gear and the second planetary gear; A housing is connected to the planetary carrier and transmits at least one of the pedal force and the driving force to a driving wheel.

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