Electric bicycle assist unit and electric bicycle

Abstract

[Problem] To suppress an increase in the burden on a rider. [Solution] This power assist unit for a bicycle comprises: a small diameter sun gear; a large diameter sun gear; a first planetary gear that meshes with the small diameter sun gear; a second planetary gear that meshes with the first planetary gear and the large diameter sun gear; a shared carrier connecting and rotatably supporting the first planetary gear and the second planetary gear; a ring gear that meshes with the second planetary gear; a first brake that can lock the rotation of the shared carrier; a second brake that can lock the rotation of the large diameter sun gear; a clutch that can separably join the small diameter sun gear and the shared carrier; an electric motor that assists the driving power in accordance with the pedaling power by the rider; a gear mechanism that transmits, to the ring gear, driving power output from the electric motor; and a case that is fixed to the ring gear and transmits at least one among the pedaling power and the driving power to a drive wheel.

Description

[Technical Field]

[0001] The present invention relates to an electrically power-assisted bicycle unit and an electrically power-assisted bicycle. [Background technology]

[0002] Patent Document 1 discloses an electrically assisted bicycle equipped with a transmission mechanism (planetary gear mechanism) having a transmission sun gear, transmission planetary gears, a transmission planetary carrier (carrier), and a transmission outer ring gear (ring gear), and a reduction mechanism having a reduction gear sun gear, reduction gear planetary gears, and a reduction gear outer ring gear. In this electrically assisted bicycle, driving force (pedaling force) from a rear sprocket is accelerated by the planetary gear mechanism and transmitted to the rear wheel, and driving force (assist torque) from a drive motor (electric motor) is decelerated by the reduction mechanism and then accelerated by the planetary gear mechanism and transmitted to the rear wheel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-168160 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electrically assisted bicycle of Patent Document 1, the planetary gear mechanism accelerates the input pedal force and transmits it to the rear wheel. Therefore, if the motor's assist torque can no longer be obtained due to a dead battery or other reason, the load may become heavier than on a normal bicycle without an electrically assisted function.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to suppress an increase in the load on the driver when assist torque from the electric motor cannot be obtained. [Means for solving the problem]

[0006] According to one aspect of the present invention, an electric assist unit for a bicycle includes a small-diameter sun gear to which a pedaling force from a rider is input, a large-diameter sun gear formed with a larger diameter than the small-diameter sun gear, a first planetary gear that meshes with the small-diameter sun gear, a second planetary gear that meshes with the first planetary gear and also meshes with the large-diameter sun gear, a shared carrier that connects and rotatably supports the first planetary gear and the second planetary gear, and a second planetary gear that meshes with the second planetary gear. the common carrier; a ring gear; a first brake capable of locking the rotation of the common carrier; a second brake capable of locking the rotation of the large diameter sun gear; a clutch that detachably connects the small diameter sun gear and the common carrier; an electric motor that assists the driving force in accordance with the pedal force applied by the driver; a gear mechanism that transmits the driving force output from the electric motor to the ring gear; and a case fixed to the ring gear that transmits at least one of the pedal force and the driving force to the drive wheels. [Effects of the Invention]

[0007] According to one aspect of the present invention, when the clutch connects the small-diameter sun gear and the shared carrier, the gear is shifted to the third gear, which is the highest gear. When the gear is shifted to the third gear, the input and output have equal speeds. Therefore, the first gear, in which the first brake stops the rotation of the shared carrier, and the second gear, in which the second brake stops the rotation of the large-diameter sun gear, can be set as low-side gears with a larger reduction ratio than the third gear. Therefore, by using the low-side gear, the driving torque due to the pedal force of the driver can be increased by deceleration. Therefore, when assist torque from the electric motor cannot be obtained, an increase in the load on the driver can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view illustrating an outline of a bicycle power assist unit and a power assisted bicycle according to an embodiment of the present invention. [Figure 2A]FIG. 2A is a skeleton diagram of the electric assist unit, showing the state in which it is switched to the first stage. [Figure 2B] FIG. 2B is a nomographic diagram of the electric assist unit, showing the state when switched to the first stage. [Figure 3A] FIG. 3A is a skeleton diagram of the electric assist unit, showing the state in which it is switched to the second stage. [Figure 3B] FIG. 3B is a nomographic diagram of the electric assist unit, showing the state when switched to the second stage. [Figure 4A] FIG. 4A is a skeleton diagram of the electric assist unit, showing the state in which it is switched to the third stage. [Figure 4B] FIG. 4B is a nomographic diagram of the electric assist unit, showing the state when switched to the third speed. [Figure 5] FIG. 5 is a cross-sectional view of the electric assist unit, showing the state in which it is switched to the first stage. [Figure 6] FIG. 6 is a diagram showing the meshing relationship of each gear in the planetary gear mechanism. [Figure 7] FIG. 7 is a cross-sectional view of the electric assist unit, showing the state in which it is switched to the second stage. [Figure 8] FIG. 8 is a cross-sectional view of the electric assist unit, showing the state in which it is switched to the third speed. DETAILED DESCRIPTION OF THE INVENTION

[0009] Below, with reference to the drawings, we will explain an electric assist unit for a bicycle (hereinafter simply referred to as an "electric assist unit") 100 according to an embodiment of the present invention and an electric assist bicycle (hereinafter simply referred to as a "bicycle") 1 equipped with the electric assist unit 100.

[0010] First, the overall configuration of a bicycle 1 will be described with reference to FIG.

[0011] FIG. 1 is a side view illustrating an outline of a bicycle 1 equipped with an electric assist unit 100. As shown in FIG.

[0012] As shown in Figure 1, the bicycle 1 includes a frame 2, a front wheel 3a, a rear wheel 3b as a driving wheel, a handlebar 4, a saddle 5, a driving sprocket 6a, a driven sprocket 6b as a sprocket, a chain 6c, a pair of pedals 7, a pair of crank arms 7b as a crank portion, a crankshaft 7c, a support shaft 8, a controller 9a, a power storage unit 9b, and an electric assist unit 100.

[0013] Bicycle 1 is ridden by a rider sitting astride saddle 5 and pedaling crank arms 7b via pedals 7. Bicycle 1 drives rear wheel 3b with pedal force (driving torque) transmitted from crank arms 7b to crankshaft 7c and driving force (assist torque) from electric assist unit 100, the magnitude of which corresponds to the pedal force.

[0014] The frame 2 is a so-called diamond frame that is generally parallelogram-shaped when viewed from the side. A front wheel 3a and a rear wheel 3b are rotatably attached to the frame 2. The frame 2 has a front fork 2a that supports the front wheel 3a.

[0015] The front wheel 3a is steered left and right by the rotation of the front fork 2a caused by the rider's operation of the handlebars 4.

[0016] The rear wheel 3b rotates around a support shaft 8. A driven sprocket 6b and an electric assist unit 100 are attached to the rear wheel 3b.

[0017] The driving torque is transmitted to the driven sprocket 6b via a chain 6c that is wound around the driving sprocket 6a, to which the driving force from the crank arm 7b is input.

[0018] The electric assist unit 100 generates an assist torque according to the pedaling force applied by the rider. The electric assist unit 100 can switch between three gears: first gear (lowest gear), second gear, and third gear (highest gear). The electric assist unit 100 will be described in detail later.

[0019] The pedal 7 is used by the driver to input driving torque, and is connected to a crankshaft 7c via a crank arm 7b.

[0020] The support shaft 8 is attached to the frame 2. The support shaft 8 is provided so as to be unable to rotate relative to the frame 2.

[0021] The controller 9a is composed of a microcomputer equipped with a CPU, RAM, ROM, input / output interface, etc. The controller 9a can also be composed of multiple microcomputers. The controller 9a performs various processes by having the CPU read and execute programs stored in the ROM. Specifically, the controller 9a calculates an assist torque based on an electrical signal corresponding to the magnitude of the pedal force input from a torque sensor (not shown), which will be described later, and outputs a command signal so that the electric motor 70 generates the assist torque.

[0022] The power storage unit 9b is a rechargeable secondary battery such as a nickel-metal hydride battery, a lithium-ion battery, etc. The power storage unit 9b is provided so as to be detachable from the frame 2.

[0023] Next, the configuration of the electric assist unit 100 and each gear will be described with reference to Figures 2A to 4B. Here, only the input and output of the pedal force from the driver will be described, and the input and output of the assist torque from the electric motor 70 will be described in detail later with reference to Figures 5 to 8.

[0024] FIG. 2A is a skeleton diagram of the electric assist unit 100, showing the state when switched to the first stage. FIG. 2B is a nomographic diagram of the electric assist unit 100, showing the state when switched to the first stage. FIG. 3A is a skeleton diagram of the electric assist unit 100, showing the state when switched to the second stage. FIG. 3B is a nomographic diagram of the electric assist unit 100, showing the state when switched to the second stage. FIG. 4A is a skeleton diagram of the electric assist unit 100, showing the state when switched to the third stage. FIG. 4B is a nomographic diagram of the electric assist unit 100, showing the state when switched to the third stage.

[0025] As shown in FIG. 2A, the electric assist unit 100 includes a planetary gear mechanism 20, a low brake 21 as a first brake, a second brake 22 as a second brake, and a clutch 23.

[0026] The planetary gear mechanism 20 includes a small diameter sun gear 31, a large diameter sun gear 32, a short planetary gear 41 as a first planetary gear, a long planetary gear 42 as a second planetary gear, a carrier 50 as a shared carrier, and a ring gear 60.

[0027] A pedal depression force by the driver is input to small diameter sun gear 31. Large diameter sun gear 32 is formed to have a larger diameter than small diameter sun gear 31.

[0028] The short planetary gear 41 meshes with the small diameter sun gear 31. The long planetary gear 42 meshes with the short planetary gear 41 and also with the large diameter sun gear 32.

[0029] The carrier 50 connects the short planetary gear 41 and the long planetary gear 42 and supports them rotatably.

[0030] The ring gear 60 meshes with the long planetary gear 42. A case 10 (see FIG. 5) that supports the rear wheel 3b rotatably relative to the support shaft 8 is fixed to the ring gear 60.

[0031] Low brake 21 can lock the rotation of carrier 50. Second brake 22 can lock the rotation of large diameter sun gear 32. Clutch 23 connects small diameter sun gear 31 and carrier 50 so as to be able to be separated from each other.

[0032] As shown in FIG. 2A, when the gear is switched to first gear, which is the lowest gear, low brake 21 fixes carrier 50 to support shaft 8 and locks it so that it cannot rotate. Driving torque input from driven sprocket 6b is transmitted from small sun gear 31 to short planetary gear 41, and from short planetary gear 41 to ring gear 60 via long planetary gear 42. At this time, because carrier 50 is locked so that it cannot rotate, the pedal force input from small sun gear 31 is reduced in speed and transmitted from ring gear 60 to rear wheel 3b. Therefore, as shown in FIG. 2B, the driver's pedal force is transmitted to rear wheel 3b at the largest reduction ratio.

[0033] As shown in FIG. 3A, when the gear is shifted to second gear, second brake 22 fixes large-diameter sun gear 32 to support shaft 8, locking it so that it cannot rotate. Driving torque input from driven sprocket 6b is transmitted from small-diameter sun gear 31 to short planetary gear 41, and from short planetary gear 41 to ring gear 60 via long planetary gear 42. At this time, because large-diameter sun gear 32 is locked so that it cannot rotate, the pedal force input from small-diameter sun gear 31 is reduced in speed and transmitted from ring gear 60 to rear wheel 3b. Therefore, as shown in FIG. 3B, the driver's pedal force is transmitted to rear wheel 3b at a smaller reduction ratio than when the gear is first gear.

[0034] As shown in Fig. 4A, when the gear position is switched to the third gear, which is the highest gear, clutch 23 connects small-diameter sun gear 31 and carrier 50 to rotate them together. Driving torque input from driven sprocket 6b is transmitted from small-diameter sun gear 31 to short planetary gear 41, from short planetary gear 41 to ring gear 60 via long planetary gear 42, and also to carrier 50 via clutch 23, and from carrier 50 to ring gear 60 via long planetary gear 42. At this time, small-diameter sun gear 31 and carrier 50 are connected to rotate together, so that the rotational speeds of small-diameter sun gear 31 and ring gear 60 are the same, as shown in Fig. 4B. Therefore, when the gear is in the first or second gear, it is a reduction gear, whereas when the gear is in the third gear, the pedal force input from the small diameter sun gear 31 is transmitted from the ring gear 60 to the rear wheel 3b at a constant speed without being reduced.

[0035] As described above, when clutch 23 connects small-diameter sun gear 31 and carrier 50, the gear is shifted to third gear, which is the highest gear. When the gear is shifted to third gear, the input and output have equal speeds. Therefore, first gear, in which low brake 21 stops the rotation of carrier 50, and second gear, in which second brake 22 stops the rotation of large-diameter sun gear 32, can be set as low-side gears with a larger reduction ratio than third gear.

[0036] Therefore, when assist torque from the electric motor 70 is no longer available due to, for example, the power storage unit 9b running out of charge (described later), the driver can use a lower gear to decelerate and increase the driving torque due to the pedal force. Therefore, when assist torque from the electric motor 70 is no longer available, an increase in the driver's load can be suppressed. Specifically, when assist torque is available, the driver's load is low, so the rear wheel 3b, which is the driving wheel, is often set to the highest gear, which rotates fastest relative to the rotation of the pedals 7. However, when assist torque is no longer available, the driver can shift from the highest gear to a lower gear to increase torque due to the reduction ratio, thereby suppressing an increase in the driver's load. Furthermore, in the third gear, which is the highest gear that is often selected when assist torque is available, the clutch 23 locks the small-diameter sun gear 31 and the carrier 50 and rotates them together. This suppresses torque transmission by the gears of the planetary gear mechanism 20, reduces wear on the planetary gear mechanism 20, and improves the durability of the electric assist unit 100.

[0037] Next, the specific configuration of the electric assist unit 100 and each gear position will be described with reference to FIGS.

[0038] Fig. 5 is a cross-sectional view of the electric assist unit 100, showing a state in which it has been switched to the first speed. Fig. 6 is a view showing the meshing relationship of the gears in the planetary gear mechanism 20. Fig. 7 is a cross-sectional view of the electric assist unit 100, showing a state in which it has been switched to the second speed. Fig. 8 is a cross-sectional view of the electric assist unit 100, showing a state in which it has been switched to the third speed.

[0039] As shown in FIG. 5, the electric assist unit 100 includes a case 10, a planetary gear mechanism 20, a low brake 21 as a first brake, a second brake 22 as a second brake, a clutch 23, an electric motor 70, a gear mechanism 73, a power input member 90, a one-way clutch 81, a one-way clutch 82, a first sliding engagement member 91, a transmission shaft 92, and a second sliding engagement member 94.

[0040] The case 10 supports the rear wheel 3b rotatably about the support shaft 8. The case 10 is fixed to the ring gear 60 of the planetary gear mechanism 20.

[0041] Case 10 supports rear wheel 3b rotatably relative to support shaft 8, supports ring gear 60 of planetary gear mechanism 20 rotatably relative to support shaft 8 around the axis of ring gear 60, and rotates together with ring gear 60 relative to support shaft 8. Case 10 rotates together with rear wheel 3b relative to support shaft 8, centering on support shaft 8. Rear wheel 3b is attached to the outer periphery of case 10 via spokes (not shown).

[0042] The case 10 has a first case 10a, a second case 10b, and a plurality of bolts (not shown) as fastening members.

[0043] The first case 10a is formed in a generally cup shape with one axial surface being open over substantially the entire surface. The first case 10a is supported on the outer periphery of the power input member 90 via a bearing 16 so as to be rotatable relative to the support shaft 8. The first case 10a houses the planetary gear mechanism 20 and the one-way clutch 81. The first case 10a is disposed so that the openings thereof face the second case 10b. One flange 17 to which spokes are connected is disposed on the outer periphery of the first case 10a so as to protrude outward.

[0044] The second case 10b is formed in a generally cup shape with almost the entire other axial surface open. The second case 10b is supported on the outer periphery of the support shaft 8 via a bearing 15 so as to be rotatable relative to the support shaft 8. The second case 10b houses an electric motor 70 and a gear mechanism 73. The second case 10b and the first case 10a are provided so that their openings face each other, and the second case 10b is fastened to the first case 10a with bolts in a state where a flange 61 protruding from the outer periphery of the ring gear 60 is sandwiched between them. The other flange 17 to which spokes are connected is provided on the outer periphery of the second case 10b so as to protrude outward.

[0045] This allows the electric assist unit 100 to be assembled by simply accommodating the planetary gear mechanism 20 and one-way clutch 81 in the first case 10a and the electric motor 70 and gear mechanism 73 in the second case 10b, and then butting together the openings of the first case 10a and the second case 10b and fastening them together with bolts.

[0046] The planetary gear mechanism 20 includes a small diameter sun gear 31, a large diameter sun gear 32, a short planetary gear 41, a long planetary gear 42, a carrier 50, and a ring gear 60.

[0047] 6, planetary gear mechanism 20 has, as rotating elements, small-diameter sun gear 31, large-diameter sun gear 32, short planetary gears 41, long planetary gears 42, carrier 50, and ring gear 60. Planetary gear mechanism 20 functions as a double-pinion planetary gear mechanism.

[0048] The carrier 50 rotatably supports the short planetary gears 41 and the long planetary gears 42. The short planetary gears 41 mesh with both the small-diameter sun gear 31 and the long planetary gears 42. The long planetary gears 42 mesh with the large-diameter sun gear 32 and the ring gear 60. The large-diameter sun gear 32 is adjacent to the small-diameter sun gear 31 in the axial direction. The long planetary gears 42 also mesh with the short planetary gears 41. The short planetary gears 41 and the long planetary gears 42 are arranged adjacent to each other in the circumferential direction and mesh with each other.

[0049] As shown in Figure 5, a portion of small diameter sun gear 31 is provided on the inner periphery of power input member 90 via one-way clutch 81. Small diameter sun gear 31 is provided so as to face power input member 90. Small diameter sun gear 31 meshes with short planetary gear 41. Small diameter sun gear 31 has splines 31a on its inner periphery as first engagement portions. Small diameter sun gear 31 transmits power to short planetary gear 41 at each gear position.

[0050] The large-diameter sun gear 32 is arranged axially alongside the small-diameter sun gear 31, sandwiching the small-diameter sun gear 31 between it and the power input member 90. The large-diameter sun gear 32 has a larger outer diameter than the small-diameter sun gear 31. The large-diameter sun gear 32 meshes with the long planetary gear 42. The large-diameter sun gear 32 has internal teeth 22a of the second brake 22 formed on its inner periphery. When the second brake 22 is activated and the gear is switched to the second gear, which has a smaller reduction ratio than the first gear, the large-diameter sun gear 32 is locked by the second brake 22 so that it cannot rotate.

[0051] The short planetary gear 41 is supported by the carrier 50 via a support shaft 55. The short planetary gear 41 meshes with the small diameter sun gear 31. The short planetary gear 41 rotates relative to the carrier 50 and revolves around the outer periphery of the small diameter sun gear 31. Power is transmitted to the short planetary gear 41 from the small diameter sun gear 31 at each gear position.

[0052] The long planetary gear 42 is supported by the carrier 50 via a support shaft 56. The long planetary gear 42 is provided so as to face the inner circumferential surface of the first case 10a. The long planetary gear 42 meshes with the large diameter sun gear 32. The long planetary gear 42 rotates relative to the carrier 50 and revolves around the outer periphery of the large diameter sun gear 32. The long planetary gear 42 is formed to have a longer axial length than the short planetary gear 41. The long planetary gear 42 transmits power to the ring gear 60 regardless of the gear position.

[0053] The carrier 50 is rotatably supported within the first case 10a via bearings 50a. The carrier 50 is connected to a support shaft 55, and rotatably (rotates) the short planetary gear 41 via the support shaft 55. The carrier 50 is connected to a support shaft 56, and rotatably (rotates) the long planetary gear 42 via the support shaft 56. The carrier 50 rotates about the support shaft 56 as the short planetary gear 41 and the long planetary gear 42 revolve.

[0054] In this way, the pedal force applied by the rider is transmitted from the inner periphery to the outer periphery through the small-diameter sun gear 31, short planetary gear 41, long planetary gear 42, ring gear 60, case 10, and rear wheel 3b in that order. Therefore, the input and output paths of the driving force can be made simpler in structure than when the driving force is input from the ring gear 60 on the outer side of the carrier 50 and output to the case 10 on the outer side of the ring gear 60. Therefore, the electric assist unit 100 can be made smaller.

[0055] The carrier 50 has a first support plate 51, a second support plate 52, a third support plate 53, and a fourth support plate .

[0056] The first support plate 51 is a substantially annular plate that supports one end of a support shaft 55 that rotatably supports the short planetary gear 41 and one end of a support shaft 56 that rotatably supports the long planetary gear 42. The first support plate 51 is rotatably supported within the first case 10a via a bearing 50a.

[0057] The second support plate 52 is a substantially annular plate that supports the other end of the support shaft 56 that rotatably supports the long planetary gear 42. The second support plate 52 is provided coaxially with the first support plate 51. The outer periphery of the second support plate 52 is connected to the first support plate 51.

[0058] The third support plate 53 is a substantially annular plate that supports the other end of the support shaft 55 that rotatably supports the short planetary gear 41. The third support plate 53 is provided coaxially with the first support plate 51 and the second support plate 52. The third support plate 53 is provided between the first support plate 51 and the second support plate 52 in the axial direction. The internal teeth 23a of the clutch 23 are formed on the inner circumference of the third support plate 53.

[0059] The fourth support plate 54 is attached to the second support plate 52. The fourth support plate 54 is provided on the side of the second support plate 52 where the long planetary gear 42 is not provided. The fourth support plate 54 is a substantially annular plate. The fourth support plate 54 is provided coaxially with the first support plate 51, the second support plate 52, and the third support plate 53. The internal teeth 21a of the low brake 21 are formed on the inner circumference of the fourth support plate 54.

[0060] The ring gear 60 is supported so as to rotate together with the case 10 about the support shaft 8. The ring gear 60 meshes with the long planetary gear 42. The ring gear 60 supports a carrier 77 of the gear mechanism 73 via a one-way clutch 82, which will be described later. The ring gear 60 has a flange 61 that protrudes from its outer periphery. The ring gear 60 is attached to the case 10 with the flange 61 sandwiched between the first case 10a and the second case 10b.

[0061] The low brake 21 is a dog brake consisting of internal teeth 21a provided on the inner periphery of the fourth support plate 54 and external teeth 94b provided on the outer periphery of the second sliding engagement member 94. The low brake 21 is activated when the second sliding engagement member 94 slides and the internal teeth 21a and the external teeth 94b mesh together, and locks the carrier 50 to the support shaft 8 so that it cannot rotate.

[0062] Second brake 22 is a dog brake made up of internal teeth 22a provided on the inner periphery of large diameter sun gear 32 and external teeth 94b provided on the outer periphery of second sliding engagement member 94. Second brake 22 is activated when second sliding engagement member 94 slides and the internal teeth 22a and external teeth 94b mesh together, and locks large diameter sun gear 32 to support shaft 8 so that it cannot rotate.

[0063] Clutch 23 is a dog clutch consisting of internal teeth 23a provided on the inner periphery of third support plate 53 and external teeth 91a provided on the outer periphery of first sliding engagement member 91. Clutch 23 is activated when first sliding engagement member 91 slides and the internal teeth 23a and external teeth 91a mesh together, connecting small-diameter sun gear 31 and carrier 50 to rotate them integrally.

[0064] The electric motor 70 assists the driving force in accordance with the pedal force applied by the driver. The electric motor 70 is driven by a command from the controller 9a. The electric motor 70 generates an assist torque using electric power supplied from the power storage unit 9b.

[0065] The electric motor 70 has a stator 71 and a rotor 72. The stator 71 is non-rotatably supported on the outer periphery of the support shaft 8. The rotor 72 is provided on the outer periphery of the stator 71 and rotatably supported on the inner periphery of the motor support member 70a via a bearing 72a. The rotor 72 rotates relative to the stator 71. A sun gear 74 (described later) of the gear mechanism 73 is attached to the rotor 72 via a connecting member 74a. The rotor 72 rotates together with the sun gear 74.

[0066] The motor support member 70a is non-rotatably supported by the support shaft 8. The motor support member 70a rotatably supports the rotor 72 via a bearing 72a. The motor support member 70a non-rotatably supports a ring gear 78 (described later) of the gear mechanism 73.

[0067] The torque sensor detects the driving torque generated when the rider pedals the crank arm 7b via the pedals 7 and transmitted to the crankshaft 7c. The torque sensor is, for example, a non-contact torque sensor that detects torque based on the torsion of the crankshaft 7c measured magnetically.

[0068] The gear mechanism 73 transmits the driving force output from the electric motor 70 to the ring gear 60. The gear mechanism 73 has a sun gear 74, a large diameter planetary gear 75, a small diameter planetary gear 76, a carrier 77, and a ring gear 78.

[0069] The sun gear 74 is rotatably provided on the outer periphery of the support shaft 8. The sun gear 74 transmits the assist torque of the electric motor 70 to the large diameter planetary gear 75.

[0070] Large diameter planetary gear 75 is rotatably supported by carrier 77 via support shaft 79. Large diameter planetary gear 75 meshes with sun gear 74. Large diameter planetary gear 75 is formed to have a larger outer diameter than small diameter planetary gear 76. Assist torque from electric motor 70 is transmitted to large diameter planetary gear 75 via sun gear 74 regardless of the gear position.

[0071] The small diameter planetary gear 76 is rotatably supported by a carrier 77 via a support shaft 79. The small diameter planetary gear 76 is aligned with the large diameter planetary gear 75 in the axial direction and is located closer to the bottom surface of the second case 10b (the bottom surface of the second case 10b, which is formed in a generally cup-like shape with an opening) than the large diameter planetary gear 75. The small diameter planetary gear 76 is located coaxially with the large diameter planetary gear 75 and rotates integrally therewith. The small diameter planetary gear 76 meshes with the inner periphery of a ring gear 78.

[0072] The carrier 77 is rotatably supported on the fourth support plate 54 of the carrier 50 via a bearing 77a. The carrier 77 is provided on the inner periphery of the ring gear 60 via a one-way clutch 82.

[0073] The ring gear 78 is supported non-rotatably on the support shaft 8 via the motor support member 70a. The ring gear 78 meshes with the small diameter planetary gear 76.

[0074] One-way clutch 81 is provided between the outer periphery of a cylindrical protrusion of small diameter sun gear 31 that protrudes toward driven sprocket 6b and the inner periphery of power input member 90. One-way clutch 81 switches between a state in which the pedal force applied by the driver is transmitted to small diameter sun gear 31 and a state in which the rotation of small diameter sun gear 31 is not transmitted to pedals 7. One-way clutch 81 transmits the pedal force applied by the driver to small diameter sun gear 31 via power input member 90. One-way clutch 81 does not transmit the rotation of small diameter sun gear 31 to pedals 7.

[0075] In this way, by providing the one-way clutch 81, when the rotational speed of the power input member 90 is faster than the rotational speed of the small diameter sun gear 31, the rotation of the small diameter sun gear 31 is not transmitted to the pedal 7, so that the pedal 7 can be stopped when the rear wheel 3b is rotating at high speed due to inertia.

[0076] The one-way clutch 82 is provided between the inner periphery of the ring gear 60 and the outer periphery of the carrier 77. The one-way clutch 82 switches between a state in which the driving force of the electric motor 70 is transmitted to the ring gear 60 and a state in which the rotation of the ring gear 60 is not transmitted to the electric motor 70. The one-way clutch 82 transmits the driving force of the electric motor 70 to the ring gear 60. The one-way clutch 82 does not transmit the rotation of the ring gear 60 to the electric motor 70.

[0077] Power input member 90 is provided on the inner periphery of driven sprocket 6b, to which pedal force is input. Power input member 90 is a cylindrical member rotatably provided on the outer periphery of support shaft 8 via bearing 90a. Power input member 90 transmits the driving torque input from driven sprocket 6b to small-diameter sun gear 31 via one-way clutch 81.

[0078] The transmission shaft 92 is capable of sliding axially inside the support shaft 8, and switches to selectively activate the low brake 21, the second brake 22, and the clutch 23 depending on the sliding position (the position of the transmission shaft 92 inside the support shaft 8, the position at which the transmission shaft 92 stops inside the support shaft 8 as a result of the transmission shaft 92 moving in the axial direction of the support shaft 8).

[0079] This allows the gear position to be changed simply by changing the axial position of the speed change shaft 92 based on the rider's operation. Therefore, for example, the rider can change the gear position by operating a lever or the like at hand, just like changing gears on a normal bicycle.

[0080] The connecting member 93 is provided perpendicular to the central axis of the transmission shaft 92, and engages with the transmission shaft 92 in the axial direction. The connecting member 93 connects the transmission shaft 92 and the second sliding engagement member 94, and allows them to move together in the axial direction.

[0081] The first sliding engagement member 91 is provided so as to be slidable in the axial direction of the support shaft 8 relative to the small diameter sun gear 31. The first sliding engagement member 91 switches the operating state of the clutch 23 depending on the sliding position. The first sliding engagement member 91 engages with the small diameter sun gear 31 and rotates together with the small diameter sun gear 31. The first sliding engagement member 91 has external teeth 91a, a spline 91b as a second engagement portion, and a locking portion 91c.

[0082] The splines 91b engage with the splines 31a of the small-diameter sun gear 31. The splines 91b are formed to have an axial length shorter than that of the splines 31a. The splines 91b are axially movable relative to the splines 31a while engaged with the splines 31a.

[0083] The locking portion 91c is locked to the second sliding engagement member 94 so as to be immovable relative to the second sliding engagement member 94 in the axial direction. The locking portion 91c is rotatable relative to the second sliding engagement member 94 in the circumferential direction. As a result, the second sliding engagement member 94 is supported on the support shaft 8 so as to be imrotatable, whereas the first sliding engagement member 91 is supported on the support shaft 8 so as to be rotatable.

[0084] The second sliding engagement member 94 moves in the axial direction of the support shaft 8 together with the first sliding engagement member 91 as the transmission shaft 92 slides, and is supported non-rotatably on the support shaft 8. The second sliding engagement member 94 switches the operating states of the low brake 21 and the second brake 22 depending on its sliding position. The second sliding engagement member 94 has a spline 94a as a third engagement portion and external teeth 94b.

[0085] The second sliding engagement member 94 is a member consisting of two coaxial cylindrical portions. A spline 94a is formed on the inner peripheral surface of the small-diameter cylindrical portion located on the inner peripheral side of the second sliding engagement member 94. External teeth 94b are formed on the outer peripheral surface of the large-diameter cylindrical portion located on the outer peripheral side of the second sliding engagement member 94.

[0086] The spline 94a engages with a spline 8a serving as a fourth engaging portion formed on the outer periphery of the support shaft 8. The spline 94a is formed to have a shorter axial length than the spline 8a. While engaged with the spline 8a, the spline 94a is movable in the axial direction relative to the spline 8a.

[0087] In this way, by providing the first sliding engagement member 91 and the second sliding engagement member 94, it is possible to selectively activate any one of the low brake 21, the second brake 22, and the clutch 23 simply by sliding the first sliding engagement member 91 and the second sliding engagement member 94 in the axial direction.

[0088] Next, each gear of the electric assist unit 100 will be described.

[0089] In the state shown in Fig. 5, the gear position of the electric assist unit 100 is shifted to the first gear. At this time, the internal teeth 21a of the low brake 21 are engaged with the external teeth 94b, so that the carrier 50 is fixed to the support shaft 8 and locked so as not to rotate. The driving torque input from the driven sprocket 6b is transmitted from the small diameter sun gear 31 to the short planetary gear 41, and from the short planetary gear 41 to the ring gear 60 via the long planetary gear 42. At this time, because the carrier 50 is locked so as not to rotate, the pedal force input from the small diameter sun gear 31 is reduced in speed and transmitted from the ring gear 60 to the rear wheel 3b. Therefore, the pedal force of the driver is transmitted to the rear wheel 3b at the largest reduction ratio.

[0090] From this state, when the transmission shaft 92 slides in the direction retracting from the case 10 (moves in the axial direction of the support shaft 8) based on the driver's operation, the first sliding engagement member 91 and the second sliding engagement member 94 move toward the driven sprocket 6b along the axial direction of the support shaft 8. As a result, the external teeth 94b of the second sliding engagement member 94 disengage from the internal teeth 21a of the fourth support plate 54 and mesh with the internal teeth 22a of the large-diameter sun gear 32. This switches to the state shown in FIG. 7.

[0091] In the state shown in FIG. 7 , the gear position of the electric assist unit 100 is shifted to the second gear. At this time, the internal teeth 22a and the external teeth 94b of the second brake 22 are engaged, so that the large-diameter sun gear 32 is fixed to the support shaft 8 and locked so as not to rotate. The driving torque input from the driven sprocket 6b is transmitted from the small-diameter sun gear 31 to the short planetary gears 41, and from the short planetary gears 41 to the ring gear 60 via the long planetary gears 42. At this time, because the large-diameter sun gear 32 is locked so as not to rotate, the pedal force input from the small-diameter sun gear 31 is reduced in speed and transmitted from the ring gear 60 to the rear wheel 3b. Therefore, the pedal force of the driver is transmitted to the rear wheel 3b at a smaller reduction ratio than when the gear position is the first gear.

[0092] For example, when traveling up a steep slope, the driver can reduce the required pedal force by switching the gear to second gear, which has a speed reduction ratio compared to third gear, thereby preventing the driver's load from increasing.

[0093] From this state, when the speed change shaft 92 slides further in the direction retracting from the case 10 based on the driver's operation, the first sliding engagement member 91 and the second sliding engagement member 94 move toward the driven sprocket 6b along the axial direction of the support shaft 8. As a result, the external teeth 94b of the second sliding engagement member 94 disengage from the internal teeth 22a of the large-diameter sun gear 32, and the external teeth 91a of the first sliding engagement member 91 mesh with the internal teeth 23a of the third support plate 53. This switches to the state shown in FIG.

[0094] 8, the gear position of the electric assist unit 100 has been shifted to the third gear. At this time, the internal teeth 23a and external teeth 91a of the clutch 23 are engaged with each other, so that the small diameter sun gear 31 and the carrier 50 are connected to each other and rotate together. The driving torque input from the driven sprocket 6b is transmitted from the small diameter sun gear 31 to the short planetary gears 41, from the short planetary gears 41 to the ring gear 60 via the long planetary gears 42, and also transmitted to the carrier 50 via the clutch 23, and from the carrier 50 to the ring gear 60 via the long planetary gears 42. At this time, the small diameter sun gear 31 and the carrier 50 are connected to each other and rotate together, so that the rotational speeds of the small diameter sun gear 31 and the ring gear 60 are the same. Therefore, when the gear is in the first or second gear, it is a reduction gear, whereas when the gear is in the third gear, the pedal force input from the small diameter sun gear 31 is transmitted from the ring gear 60 to the rear wheel 3b at a constant speed without being reduced.

[0095] In this way, the electric assist unit 100 is configured so that the input and output have equal speeds in third gear, and first and second gears have speed reduction gear ratios. As a result, when switched to third gear, which is the highest gear and is most frequently used, the pedal force of the rider is transmitted to the case 10 without the relative rotation of each component of the planetary gear mechanism 20. Therefore, wear on each gear portion of the planetary gear mechanism 20 can be suppressed, and the durability of the electric assist unit 100 can be improved.

[0096] Furthermore, when the pedaling force of the rider is increased and transmitted to the rear wheel 3b at a certain gear, a large assist torque is required, which may increase the amount of power consumed by the electric motor 70. In contrast, the electric assist unit 100 maintains a constant speed even in the highest gear, third gear, and does not increase the pedaling force of the rider, so the required assist torque can be reduced. Therefore, the electric assist unit 100 can reduce power consumption and increase the range of the bicycle 1.

[0097] The configuration and effects of the present embodiment will now be described.

[0098] (1)(9) The electric assist unit 100 includes a small-diameter sun gear 31 to which a pedal force from the driver is input, a large-diameter sun gear 32 formed to have a larger diameter than the small-diameter sun gear 31, a short planetary gear 41 that meshes with the small-diameter sun gear 31, a long planetary gear 42 that meshes with the short planetary gear 41 and also meshes with the large-diameter sun gear 32, a carrier 50 that connects the short planetary gear 41 and the long planetary gear 42 and supports them rotatably, and a rear wheel that meshes with the long planetary gear 42. The vehicle comprises a ring gear 60, a low brake 21 capable of locking the rotation of the carrier 50, a second brake 22 capable of locking the rotation of the large diameter sun gear 32, a clutch 23 that connects the small diameter sun gear 31 and the carrier 50 in a detachable manner, an electric motor 70 that assists the driving force in accordance with the pedal force applied by the driver, a gear mechanism 73 that transmits the driving force output from the electric motor 70 to the ring gear 60, and a case 10 fixed to the ring gear 60 and that transmits at least one of the pedal force and the driving force to the rear wheel 3b.

[0099] According to this configuration, when clutch 23 connects small-diameter sun gear 31 and carrier 50, the gear is shifted to third gear, which is the highest gear. When the gear is shifted to third gear, the input and output have equal speeds. Therefore, the first gear, in which low brake 21 stops the rotation of carrier 50, and the second gear, in which second brake 22 stops the rotation of large-diameter sun gear 32, can be set as low-side gears with a larger reduction ratio than third gear. Therefore, by using the low-side gear, the driving torque due to the pedal force of the driver can be increased by deceleration. Therefore, when assist torque from electric motor 70 cannot be obtained, an increase in the load on the driver can be suppressed.

[0100] Furthermore, the pedal force applied by the rider is transmitted from the inner periphery to the outer periphery in the following order: small-diameter sun gear 31, short planetary gear 41, long planetary gear 42, ring gear 60, case 10, and rear wheel 3b. Therefore, the input and output paths of the driving force can be made simpler in structure than when the driving force is input from ring gear 60 on the outer side of carrier 50 and output to case 10 on the outer side of ring gear 60. Therefore, the electric assist unit 100 can be made smaller.

[0101] (2) The case 10 of the electric assist unit 100 supports the rear wheel 3 b rotatably about the support shaft 8 .

[0102] With this configuration, the pedal force of the rider is input to the small diameter sun gear 31 of the electric assist unit 100 via the drive sprocket 6a and the driven sprocket 6b. The driving force transmitted from the drive sprocket 6a to the driven sprocket 6b is accelerated, and the torque input to the small diameter sun gear 31 is reduced accordingly. This makes it possible to reduce the strength of each component of the electric assist unit 100, and to prevent the electric assist unit 100 from becoming larger.

[0103] (3) The electric assist unit 100 further includes a one-way clutch 81 that switches between a state in which the pedal force of the driver is transmitted to the small diameter sun gear 31 and a state in which the rotation of the small diameter sun gear 31 is not transmitted to the pedal.

[0104] According to this configuration, by providing a one-way clutch 81, when the small diameter sun gear 31 is rotating faster than the pedal 7, the rotation of the small diameter sun gear 31 is not transmitted to the pedal 7, so that the pedal 7 can be stopped when the rear wheel 3b is rotating at high speed due to inertia.

[0105] (4) The electric assist unit 100 further includes a speed change shaft 92 that is axially slidable inside the support shaft 8 and switches between the low brake 21, the second brake 22, and the clutch 23 to selectively activate them.

[0106] With this configuration, the gear position can be changed simply by changing the axial position of the speed change shaft 92 based on the rider's operation. Therefore, for example, the rider can change the gear position by operating a lever or the like at hand, just like changing gears on a normal bicycle.

[0107] (5) The electric assist unit 100 further includes a first sliding engagement member 91 that is axially slidable relative to the small-diameter sun gear 31 and engages with the small-diameter sun gear 31 so as to rotate together with the small-diameter sun gear 31, and a second sliding engagement member 94 that moves axially together with the first sliding engagement member 91 as the transmission shaft 92 slides and is supported non-rotatably on the support shaft 8, and the clutch 23 is switched depending on the position of the first sliding engagement member 91 (the position, sliding position of the transmission shaft 92 inside the support shaft 8), and the low brake 21 and the second brake 22 are switched depending on the position of the second sliding engagement member 94 (the position, sliding position of the transmission shaft 92 inside the support shaft 8).

[0108] According to this configuration, it is possible to selectively activate any one of the low brake 21, the second brake 22, and the clutch 23 simply by sliding the first sliding engagement member 91 and the second sliding engagement member 94 in the axial direction.

[0109] (6) When the gear is shifted to the first gear, the low brake 21 fixes the carrier 50 to the support shaft 8, preventing it from rotating, and the pedal force input from the small-diameter sun gear 31 is decelerated and transmitted from the ring gear 60 to the rear wheel 3b.

[0110] According to this configuration, when assist torque from the electric motor 70 cannot be obtained due to, for example, the power storage unit 9b running out of charge, the driver can increase the driving torque due to the pedaling force by decelerating by switching the gear to the first gear, which has the largest reduction ratio. Therefore, when assist torque from the electric motor 70 cannot be obtained, an increase in the load on the driver can be suppressed.

[0111] (7) When the gear is shifted to the second gear, the second brake 22 fixes the large diameter sun gear 32 to the support shaft 8, preventing it from rotating, and the pedal force input from the small diameter sun gear 31 is decelerated and transmitted from the ring gear 60 to the rear wheel 3b.

[0112] With this configuration, when traveling up a steep slope, the driver can reduce the required pedal force by switching to the second gear, which has a speed-reduction gear ratio, thereby preventing the driver's load from increasing.

[0113] (8) When the gear is shifted to the third gear, the clutch 23 connects the small diameter sun gear 31 and the carrier 50, causing them to rotate together, and the pedal force input from the small diameter sun gear 31 is transmitted at a constant speed from the ring gear 60 to the rear wheel 3b.

[0114] According to this configuration, the electric assist unit 100 is configured so that the input and output are equal in third gear, and first and second gears have a speed reduction side gear ratio. As a result, when switched to third gear, which is the highest gear and is most frequently used, the pedal force of the rider is transmitted directly to the case 10 without passing through the components of the planetary gear mechanism 20. This improves the durability of the electric assist unit 100.

[0115] Although an embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0116] For example, in the above embodiment, the electric assist unit 100 is attached to the rear wheel 3b together with the driven sprocket 6b. However, the electric assist unit 100 may also be attached to the crankshaft 7c together with the driving sprocket 6a. In this case, the rider may pedal the crank arm 7b via the pedal 7, and the pedaling force (driving torque) transmitted from the crank arm 7b to the crankshaft 7c may be input to the small-diameter sun gear 31. Alternatively, the output of the electric assist unit 100 may be transmitted from the ring gear 60 via the case 10 to the driving sprocket 6a, and then to the driven sprocket 6b via a chain 6c wound around the driving sprocket 6a, thereby rotating the rear wheel 3b.

[0117] In the above embodiment, the rotor 72 is a so-called outer rotor that is provided on the outer periphery of the stator 71. Alternatively, the stator may be provided on the outer periphery side, and the rotor may be a so-called inner rotor that rotates on the inner periphery of the stator. [Explanation of symbols]

[0118] 100 Electric assist unit 1. Bicycle (electrically assisted bicycle) 3b Rear wheels (drive wheels) 6b Driven sprocket (sprocket) 7 Pedals 8 Support shaft 10 cases 21 Low brake (first brake) 22 Second brake (second brake) 23 Clutch 31 Small diameter sun gear 32 Large diameter sun gear 41 Short planetary gear (first planetary gear) 42 Long planetary gear (second planetary gear) 50 Carriers (Shared Carriers) 60 ring gear 70 Electric Motor 73 Gear mechanism 81 One-way clutch 91 First sliding engagement member 92 Speed ​​change shaft 94 Second sliding engagement member

Claims

1. An electric assist unit for a bicycle, a small diameter sun gear to which a pedal force from a driver is input; a large-diameter sun gear formed to have a diameter larger than that of the small-diameter sun gear; a first planetary gear that meshes with the small diameter sun gear; a second planetary gear that meshes with the first planetary gear and with the large diameter sun gear; a common carrier that connects the first planetary gear and the second planetary gear and rotatably supports them; a ring gear that meshes with the second planetary gear; a first brake capable of locking rotation of the shared carrier; a second brake capable of locking the rotation of the large diameter sun gear; a clutch that detachably couples the small diameter sun gear and the common carrier; an electric motor that assists the driving force in accordance with the pedal force applied by the driver; a gear mechanism that transmits a driving force output from the electric motor to the ring gear; a case fixed to the ring gear and configured to transmit at least one of a pedal force and a driving force to a driving wheel; Electric assist unit for bicycles.

2. 2. The bicycle power assist unit according to claim 1, The case supports the drive wheel rotatably relative to a support shaft. Electric assist unit for bicycles.

3. 3. The bicycle power assist unit according to claim 2, a one-way clutch that switches between a state in which a pedal depression force applied by a driver is transmitted to the small diameter sun gear and a state in which rotation of the small diameter sun gear is not transmitted to the pedals; Electric assist unit for bicycles.

4. 3. The bicycle power assist unit according to claim 2, a transmission shaft that is axially slidable inside the support shaft and switches between the first brake, the second brake, and the clutch to selectively operate the first brake, the second brake, and the clutch; Electric assist unit for bicycles.

5. 5. The bicycle power assist unit according to claim 4, a first sliding engagement member that is provided axially slidably relative to the small diameter sun gear and engages with the small diameter sun gear so as to rotate together with the small diameter sun gear; a second sliding engagement member that moves axially together with the first sliding engagement member as the transmission shaft slides and is supported non-rotatably on the support shaft; Further provided with The clutch is switched depending on the position of the first sliding engagement member, and the first brake and the second brake are switched depending on the position of the second sliding engagement member. Electric assist unit for bicycles.

6. 6. An electric assist unit for a bicycle according to any one of claims 2 to 5, When the gear position is switched to the first position, the first brake fixes the common carrier to the support shaft and locks it so that it cannot rotate, and the pedal force input from the small diameter sun gear is decelerated and transmitted from the ring gear to the drive wheels. Electric assist unit for bicycles.

7. 6. An electric assist unit for a bicycle according to any one of claims 2 to 5, When the gear position is switched to the second position, the second brake fixes the large diameter sun gear to the support shaft and locks it so that it cannot rotate, and the pedal force input from the small diameter sun gear is decelerated and transmitted from the ring gear to the drive wheels. Electric assist unit for bicycles.

8. 6. An electric assist unit for a bicycle according to any one of claims 2 to 5, When the gear stage is switched to the third stage, the clutch connects the small diameter sun gear and the shared carrier to rotate them together, and the pedal force input from the small diameter sun gear is transmitted from the ring gear to the drive wheels at a constant speed. Electric assist unit for bicycles.

9. An electrically assisted bicycle, a small diameter sun gear to which a pedal force from a driver is input; a large-diameter sun gear formed to have a diameter larger than that of the small-diameter sun gear; a first planetary gear that meshes with the small diameter sun gear; a second planetary gear that meshes with the first planetary gear and with the large diameter sun gear; a common carrier that connects the first planetary gear and the second planetary gear and rotatably supports them; a ring gear that meshes with the second planetary gear; a first brake capable of locking rotation of the shared carrier; a second brake capable of locking the rotation of the large diameter sun gear; a clutch that detachably couples the small diameter sun gear and the common carrier; an electric motor that assists the driving force in accordance with the pedal force applied by the driver; a gear mechanism that transmits a driving force output from the electric motor to the ring gear; a case fixed to the ring gear and configured to transmit at least one of a pedal force and a driving force to a driving wheel; Equipped with Electric assist bicycle.

Images