Pedal force detection mechanism in an electric assist bicycle

Abstract

To provide a pedal force detection mechanism for an electric-assist bicycle.SOLUTION: A pedal force detection mechanism for an electric-assist bicycle comprises: a pedal force redirection unit that transmits the pedal force from a crankshaft in one direction and redirects it along the axial direction of the crankshaft; a main thrust-retaining bearing that abuts the pedal force redirection unit in order to transmit the redirected pedal force; a strain detection unit which includes a support ring base that contacts a bearing housing and has an axial strain clearance between itself and the main thrust-retaining bearing, an elastic ring base that is placed externally to the support ring base and positioned between the main thrust-retaining bearing and the support ring base and a strain gauge; and a main transmission gear which includes an integrally molded internal ring body on the inner side of a main gear. An axial movement clearance is provided between the pedal force redirection unit and the internal ring body.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a pedaling force detection mechanism in an electric assist bicycle, and more particularly to a pedaling force detection mechanism that detects pedaling force and activates an assist motor of the electric assist bicycle to provide assist power to a crankshaft.

Background Art

[0002] In recent years, an electric assist bicycle boom has been sweeping the world. An electric assist bicycle is a bicycle equipped with an electric assist motor and a battery. When a rider pedals, the assist motor provides appropriate assist power according to the pedaling force, enabling the rider to move easily and labor-savingly even when traveling on a steep slope or a bumpy road surface.

[0003] As a method for detecting pedaling force, generally, a torque detection unit is installed outside a sleeve of a bearing in a crankshaft of an electric assist bicycle, and by detecting a change in torque, it is determined whether to activate the motor. However, when riding an electric assist bicycle, many riders may not be provided with appropriate assist power. This is because the change in pedaling force exceeds the sensitivity or detection range of the torque detection unit. In addition, in the prior art document TWI769802, a pedaling force detection mechanism for an electric assist bicycle is disclosed.

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a result of intensive studies to solve the above problems, the present inventor has developed a pedaling force detection mechanism in an electric assist bicycle that can surely detect a change in pedaling force and provide assist power accordingly.

Means for Solving the Problems

[0005] The present invention is suitable for being housed in the axle box of an electric assist bicycle so as to be arranged on a crankshaft movably installed in the axle box and connected to an assist power unit, transmits the pedaling force from the crankshaft in one direction, and transmits the pedaling force in the axial direction of the crankshaft The pressing force along A pedaling force turning part for turning; The pressing force For transmitting, a main thrust bearing contacting the pedaling force turning part, and the outside of the pedaling force turning part which is Contacting the axle box and having an axial strain clearance between it and the main thrust bearing, a support ring base, provided outside the support ring base, between the main thrust bearing and the support ring base provided An elastic ring base contacting them, and a strain detection unit having a strain gauge provided on the elastic ring base and communicatively connected to the assist power unit, a main gear, an inner ring body integrally formed inside the main gear, and an outer ring body fixed outside the main gear, and a main transmission gear movably provided between the crankshaft and the axle box, and the pedaling force turning part has an axial movement clearance with the inner ring body and rotates synchronously with the inner ring body, providing a pedaling force detection mechanism in an electric assist bicycle.

[0006] In an embodiment according to the present invention, the main thrust bearing is a thrust ball bearing.

[0007] In an embodiment according to the present invention, the support ring base has a support cylinder and a support ring flange. One end of the support cylinder has the axial strain clearance with the main thrust bearing, and the other end is fixed to the support ring flange. The support ring flange contacts between the elastic ring base and the axle box provided Therebetween.

[0008] In an embodiment according to the present invention, the main transmission gear is between the axle box and the main gear providedA first thrust bearing corresponding thereto, an adjusting nut locked to the crankshaft, and between the main gear and the adjusting nut provided It has a second thrust bearing corresponding thereto, and a fixed nut locked to the crankshaft and abutting against the adjusting nut, with the torsional direction being opposite to that of the adjusting nut.

[0009] In an embodiment according to the present invention, a ring-shaped fixed base, a ring-shaped magnet provided on the ring-shaped fixed base, a sensor provided on the axle box so as to sense the ring-shaped magnet, and between the ring-shaped fixed base and the pedal force turning portion provided It further includes a rotation detection unit having a third thrust bearing corresponding thereto and a first bearing provided between the axle box and the ring-shaped fixed base, and the crankshaft is fitted and fixed to the ring-shaped fixed base.

Advantages of the Invention

[0010] Thereby, the pedal force detection mechanism in the electric assist bicycle according to the present invention achieves the purpose of reliably providing assist power in response to changes in pedal force.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail with reference to specific embodiments and drawings so that the objects, features, and effects of the present invention can be fully understood.

[0013] As shown in FIGS. 1 to 10, the present invention is a pedaling force detection mechanism suitable for being housed in the axle box 5 of an electric assist bicycle, which is arranged on a crankshaft 20 movably installed in the axle box 5 and connected to an assist power unit 3. The axle box 5 may have a configuration similar to the combination of a first axle box 51 and a second axle box 52 described in TWI769802.

[0014] The first axle box 51 may have a positioning groove body 511 and a ring-shaped cover body 512 that covers the positioning groove body 511. The crankshaft 20 is installed through the ring-shaped cover body 512 of the first axle box 51, the positioning groove body 511, and the second axle box 52. Further, the axle box 5 may be an axle box with a different configuration. The assist power unit 3 may be a combination of an assist power source 31, a first reduction gear 32, and a second reduction gear 33 similar to the configuration described in TWI769802. Further, the assist power unit 3 may be a different type of assist power device.

[0015] The pedal force detection mechanism includes a pedal force turning portion 1, a main thrust bearing 13, a strain detection unit 14, and a main transmission gear 21. The pedal force turning portion 1 transmits the pedal force F from the crankshaft 20 in one direction and turns the pedal force F in the axial direction of the crankshaft 20. The pressing force along The pedal force turning portion 1 may be a combination of a one-way ratchet socket 10, a driving end face cam 11, and a driven end face cam 12 similar to the configuration described in TWI769802 so as to transmit the pedal force F from the crankshaft 20 in one direction and turn the pedal force F in the axial direction of the crankshaft 20. A bearing 111 is provided between the driving end face cam 11 and the positioning groove body 511 of the first axle box 51. Note that the pedal force turning portion 1 may be a different type of pedal force turning portion.

[0016] The main thrust bearing 13 The pressing force contacts the pedal force turning portion 1 to transmit. The main thrust bearing 13 The pressing force may contact the back ring surface 121 of the driven end face cam 12 of the pedal force turning portion 1 or other pedal force turning mechanisms as described in TWI769802 to transmit.

[0017] The strain detection unit 14 has a strain gauge 16, an elastic ring base 15, and a support ring base 17. The support ring base 17 may be made of steel, is provided outside the driven end face cam 12 of the tread force turning part 1, abuts against the bottom of the positioning groove body 511 of the axle box 5, and has an axial strain clearance 6 between it and the main thrust bearing 13.

[0018] The elastic ring base 15 may be made of aluminum and is provided outside the support ring base 17. The elastic ring base 15 abuts against the main thrust bearing 13 with its ring upper surface 151 and against the support ring base 17 with its ring bottom surface 152, thereby abutting between the main thrust bearing 13 and the support ring base 17. The strain gauge 16 is provided on the outer ring surface of the elastic ring base 15, is communicatively connected to the assist power unit 3, and is connected to the control circuit of the assist power unit 3 by wireless (e.g., RFID, infrared, or ultraviolet) or wired connection.

[0019] The main transmission gear 21 is movably provided between the crankshaft 20 and the axle box 5, and between the positioning groove body 511 of the first axle box 51 and the second axle box 52. The crankshaft 20 penetrates and is coupled to the main transmission gear 21 having a main gear 211, an inner ring body 210, and an outer ring body 212. The inner ring body 210 is integrally formed inside the main gear 211, and an inner bearing 217 is provided between the inner ring body 210 and the main gear 211 and the crankshaft 20. The outer ring body 212 is fixed outside the main gear 211, and an outer bearing 218 is provided to penetrate the second axle box 52 between it and the second axle box 52.

[0020] The axial bolt groove 2121 of the external ring body 212 may be connected to a chain ring (not shown). The axial bolt groove 122 outside the end of the driven end face cam 12 of the pedal force turning part 1 is movably connected to the axial bolt groove 2101 at the end of the internal ring body 210 in order to synchronously rotate the driven end face cam 12 of the pedal force turning part 1 with the internal ring body 210.

[0021] A support ring base 17 in which an axial movement clearance 7 having a size of 6 or more of the axial strain clearance is formed may be provided outside the connection between the driven end face cam 12 and the internal ring body 210 between the axial bolt groove 122 and the internal ring body 210. The internal ring body 210 may be provided to penetrate the bottom of the positioning groove body 511 of the first axle box 51 so as to be movably connected to the driven end face cam 12.

[0022] As described above, when the crankshaft 20 of the pedal force detection mechanism in the electric assist bicycle according to the present invention receives the pedal force F transmitted from the rider via a pedal (not shown) and a crank (not shown), the drive end face cam 11 is rotated in one direction in conjunction with the one-way ratchet socket 10 to transmit the pedal force F.

[0023] Thereafter, the driven end face cam 12 is rotated in conjunction with the drive end face cam 11 and is pushed and moved in the axial direction of the crankshaft 20 by the drive end face cam 11, so that the pedal force F is The pressing force along turned in the axial direction of the crankshaft 20. When the driven end face cam 12 moves in the axial direction of the crankshaft 20, it hits the main thrust bearing 13 and presses the main thrust bearing 13 against the ring upper surface 151 of the elastic ring base 15.

[0024] Since the ring bottom surface 152 of the elastic ring base 15 is stopped by the rear part of the support ring base 17 and the bottom of the positioning groove body 511 of the axle box 5, the elastic ring base 15 is deformed, and the piezoelectric material in the strain gauge 16 generates strain and voltage changes according to the deformation of the elastic ring base 15. Then, torque can be calculated from the voltage change, and further, the torque due to the stepping force F can be detected by the strain gauge 16. When the magnitude of the torque due to the stepping force F is equal to or greater than a predetermined torque, the assist power source 31 outputs assist power to the main gear 211 by the first reduction gear 32 and the second reduction gear 33, so that the rider can ride the bicycle easily and labor - savingly.

[0025] In addition, when the elastic ring base 15 is deformed, since there is the strain clearance 6 between the front part of the support ring base 17 and the main thrust bearing 13, when the deformation amount of the elastic ring base 15 exceeds the strain clearance 6, the support ring base 17 resists the main thrust bearing 13 so that the elastic ring base 15 will not be excessively deformed by the main thrust bearing 13 and become permanently deformed.

[0026] In addition, when the driving end - face cam 11 in the stepping - force turning part 1 pushes and moves the driven end - face cam 12 toward the crankshaft 20, since there is an axial movement clearance 7 with a magnitude equal to or greater than the axial strain clearance 6 between the driven end - face cam 12 of the stepping - force turning part 1 and the inner - circumscribing ring body 210, the driven end - face cam 12 can move freely axially in the detection process of the strain gauge 16, so that the elastic ring base 15 can be accurately deformed. Therefore, the torque due to the stepping force F can be accurately detected by the strain gauge 16.

[0027] In addition, since the inner ring body 210 is integrally formed inside the main gear 211, during assembly, it can be directly and movably connected to the driven end face cam 12 of the pedal force turning portion 1, thereby improving the workability of assembly and simplifying the processing process of the main transmission gear 21.

[0028] As shown in FIG. 13, since the pedal force detection mechanism according to the present invention can accurately detect whether there is an input of pedal force, it has a higher discrimination degree compared with the conventional pedal force detection mechanism. In addition, since the pedal force detection mechanism according to the present invention can detect a stronger pedal force, it has a wider detection range compared with the conventional pedal force detection mechanism.

[0029] As shown in FIG. 9, in one embodiment according to the present invention, the main thrust bearing 13 may be a thrust ball bearing. Thereby, the strength and durability of the main thrust bearing 13 of the present invention are improved.

[0030] As shown in FIGS. 1 to 4 and FIG. 9, in one embodiment according to the present invention, the support ring base 17 may have a support cylinder 171 and a support ring flange 172. The front portion of the support cylinder 171 has the strain clearance 6 between it and the main thrust bearing 13, the rear portion of the support cylinder 171 is fixed to the support ring flange 172, and the support ring flange 172 abuts between the ring bottom surface 152 of the elastic ring base 15 and the bottom of the positioning groove body 511 of the axle box 5. Thereby, the strength and durability of the support ring base 17 of the present invention can be improved.

[0031] As shown in FIGS. 1, 2, 5, 6 and FIG. 9, in one embodiment according to the present invention, the main transmission gear 21 may have a first thrust bearing 213 (for example, a thrust needle roller bearing), a second thrust bearing 214 (for example, a thrust ball bearing), an adjusting nut 215, and a fixing nut 216. The first thrust bearing 213 abuts between the bottom of the positioning groove body 511 of the axle box 5 and the main gear 211 and covers the inner ring body 210.

[0032] The second thrust bearing 214 contacts between the main gear 211 and the adjusting nut 215 and is provided by covering the crankshaft 20 in the external circumferential ring body 212. The adjusting nut 215 is provided by being locked to the crankshaft 20 in the external circumferential ring body 212. The fixing nut 216 is locked to the crankshaft 20, contacts the adjusting nut 215, and is arranged in the external circumferential ring body 212. Also, the twisting direction of the fixing nut 216 is opposite to that of the adjusting nut 215.

[0033] Thereby, before the assembly of the pedal force detection mechanism according to the present invention is completed, the adjusting nut 215 is screwed between the crankshaft 20 and the external circumferential ring body 212. When the strain gauge 16 detects a signal (i.e., the detection starting point of the strain gauge 16), the fixing nut 216 is screwed between the crankshaft 20 and the external circumferential ring body 212, thereby locking the adjusting nut 215 and completing the assembly of the pedal force detection mechanism according to the present invention. Thereby, the pedal force detection mechanism according to the present invention is excellent in assembly workability, and it is possible to confirm whether the strain gauge 16 can operate normally at the time of completion of assembly.

[0034] As shown in FIGS. 1, 2, 9, 11, and 12, in an embodiment according to the present invention, the pedal force detection mechanism according to the present invention may further include a rotation detection unit 19. The rotation detection unit 19 includes a sensor 191 (for example, a magnetic sensor), a ring-shaped magnet 192 (for example, a Hall sensor magnet), a ring-shaped fixed base 193, a third thrust bearing 194 (for example, a thrust needle roller bearing), and a first bearing 195. The crankshaft 20 is fitted and fixed to the fixing hole 1931 of the ring-shaped fixed base 193.

[0035] The third thrust bearing 194 abuts between the rear part of the ring-shaped fixed base 193 and the drive end face cam 11 of the pedal force turning part 1. The first bearing 195 is provided on the ring-shaped lid 512 of the axle box 5 and covers the front part of the ring-shaped fixed base 193. The ring-shaped magnet 192 is provided in a ring-shaped fixed groove 1932 in the front part of the ring-shaped fixed base 193. The sensor 191 is provided on the ring-shaped lid 512 of the axle box 5 so as to detect the ring-shaped magnet 192.

[0036] Thus, the pedal force detection mechanism according to the present invention can detect whether the crankshaft 20 is rotating and its rotation speed by the sensor 191 and the ring-shaped magnet 192. Therefore, in order to prevent a sudden acceleration of the bicycle, when the crankshaft 20 is rotating and the magnitude of the torque due to the pedal force F is equal to or greater than a predetermined torque, the assist power unit 3 provides assist power.

[0037] Although the present invention has been disclosed by suitable embodiments, it is obvious to those skilled in the art that the embodiments are merely examples of the present invention and do not limit the scope of the present invention. Any modifications and substitutions equivalent to the embodiments are considered to be included in the scope of the present invention. Therefore, the scope of the present invention is defined based on what is specified in the claims.

Description of Reference Numerals

[0038] 1 Pedal force turning part 10 One-way ratchet socket 11 Drive end face cam 111 Bearing 12 Driven end face cam 121 Back ring surface 122 Axial bolt groove 13 Main thrust bearing 14 Strain detection unit 15 Elastic ring base 151 Ring upper surface 152 Ring bottom surface 16 Strain gauge 17 Support ring base 171 Support cylinder 172 Support ring flange 19 Rotation detection unit 191 Sensor 192 Ring-shaped magnet 193 Ring-shaped fixed base 1931 Fixed hole 1932 Ring-shaped fixed groove 194 Third thrust retaining bearing 195 First bearing 20 Crankshaft 21 Main transmission gear 210 Inner ring body 2101 Axial bolt groove 211 Main gear 212 Outer ring body 2121 Axial bolt groove 213 First thrust retaining bearing 214 Second thrust retaining bearing 215 Adjusting nut 216 Locking nut 217 Inner bearing 218 Outer bearing 3 Assist power unit 31 Assist power source 32 First reduction gear 33 Second reduction gear 5 Axle box 51 First axle box 511 Positioning groove body 512 Ring-shaped cover 52 Second axle box 6 Axial strain clearance 7 Axial movement clearance F Pedal force

Claims

1. A pedaling force detection mechanism for an electric assist bicycle, which is adapted to be accommodated in the axle box of the electric assist bicycle, arranged on a crankshaft movably installed in the axle box and connected to an assist power unit, comprising: a pedaling force turning portion that transmits the pedaling force from the crankshaft in one direction and turns the pedaling force into a pressing force along the axial direction of the crankshaft; a main thrust bearing that contacts the pedaling force turning portion to transmit the pressing force; a support ring base provided outside the pedaling force turning portion, contacting the axle box and having an axial strain clearance between the main thrust bearing; an elastic ring base provided outside the support ring base, between the main thrust bearing and the support ring base and contacting them; and a strain gauge provided on the elastic ring base and communicatively connected to the assist power unit, forming a strain detection unit; a main gear, an inscribed ring body integrally formed inside the main gear, and a circumscribed ring body fixed outside the main gear, including a main transmission gear movably provided between the crankshaft and the axle box; the pedaling force turning portion rotates synchronously with the inscribed ring body while having no axial movement clearance between it and the inscribed ring body; A pedaling force detection mechanism for an electric assist bicycle.

2. The main thrust bearing is a thrust ball bearing. The pedaling force detection mechanism according to claim 1.

3. The support ring base has a support cylinder and a support ring flange. One end of the support cylinder has the axial strain clearance between it and the main thrust bearing, and the other end is fixed to the support ring flange. The support ring flange is provided between the elastic ring base and the axle box and contacts them. The pedaling force detection mechanism according to claim 1.

4. The main transmission gear has a first thrust bearing provided between the axle box and the main gear and contacting them, an adjusting nut locked to the crankshaft, a second thrust bearing provided between the main gear and the adjusting nut and contacting them, and a fixing nut locked to the crankshaft and contacting the adjusting nut, with a torsion direction opposite to that of the adjusting nut. The pedaling force detection mechanism according to claim 1.

5. A rotation detection unit further includes a ring-shaped fixed base, a ring-shaped magnet provided on the ring-shaped fixed base, a sensor provided on the journal box so as to detect the ring-shaped magnet, a third thrust bearing provided between the ring-shaped fixed base and the tread force turning portion and abutting against them, and a first bearing provided between the journal box and the ring-shaped fixed base. The crankshaft is fitted and fixed to the ring-shaped fixed base. The tread force detection mechanism according to claim 1.

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