Pedal force detection mechanism for 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 for an electrically assisted bicycle, and more particularly to a pedaling force detection mechanism that detects the pedaling force and activates the assist motor of the electrically assisted bicycle to provide assist power to the crankshaft. [Background technology]

[0002] In recent years, there has been a boom in electric-assist bicycles all over the world. An electric-assist bicycle is a bicycle equipped with an electric assist motor and a battery. When the rider pedals, the assist motor provides an appropriate amount of assist power according to the force applied to the pedal, allowing the rider to move easily and with less effort, even when riding up steep slopes or over bumpy roads.

[0003] A typical method for detecting pedaling force is to install a torque detection unit on the outside of the bearing sleeve of the crankshaft of an electrically assisted bicycle, and determine whether to start the motor by detecting changes in torque. However, many riders may not receive adequate assist power when riding an electrically assisted bicycle because the changes in pedaling force exceed the sensitivity or detection range of the torque detection unit. A pedaling force detection mechanism for an electrically assisted bicycle is disclosed in the prior art document TWI769802. Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of extensive research into solving the above problems, the present inventors have developed a pedaling force detection mechanism for an electrically assisted bicycle that can reliably detect changes in pedaling force and provide assist power accordingly. [Means for solving the problem]

[0005] The present invention is suitable for being accommodated in an axle box of an electrically assisted bicycle so as to be disposed on a crankshaft movably installed in an axle box and connected to an assist power unit, and includes a pedaling force turning section that transmits a pedaling force from the crankshaft in one direction and turns the pedaling force in the axial direction of the crankshaft, a main thrust stop bearing that abuts on the pedaling force turning section in order to transmit the turned pedaling force, a support ring base that is provided outside the pedaling force turning section, abuts on the axle box, and has an axial strain clearance between it and the main thrust stop bearing, and a support ring base that is provided outside the support ring base and turns the main thrust stop bearing. The present invention provides a pedaling force detection mechanism for an electrically assisted bicycle, comprising: a strain detection unit having an elastic ring base between a strike stop bearing and the support ring base, and a strain gauge provided on the elastic ring base and communicatively connected to the assist power unit; a main transmission gear having a main gear, an inscribed ring body integrally molded on the inside of the main gear, and an extrinsic ring body fixed to the outside of the main gear, and movably provided between the crankshaft and the axle box, wherein the pedaling force turning portion rotates synchronously with the inscribed ring body while having an axial active clearance between the inscribed ring body and the inscribed ring body.

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

[0007] In an embodiment according to the present invention, the support ring base has a support tube and a support ring flange, one end of the support tube has the axial strain clearance between the support tube and the main thrust stop bearing, and the other end is fixed to the support ring flange, The support ring flange abuts between the elastic ring base and the axle box.

[0008] In an embodiment according to the present invention, the main transmission gear includes a first thrust stop bearing between the axle box and the main gear and abutting them, an adjusting nut locked to the crankshaft, a second thrust stop bearing between the main gear and the adjusting nut and a fixing nut locked to the crankshaft and abutting the adjusting nut, the fixing nut having a twisting direction opposite to that of the adjusting nut.

[0009] In an embodiment of the present invention, the rotation detection unit further includes a ring-type fixed base, a ring-type magnet provided on the ring-type fixed base, a sensor provided on the axle box to detect the ring-type magnet, a third thrust stop bearing between the ring-type fixed base and the pedal force turning portion, and a first bearing provided between the axle box and the ring-type fixed base, and the crankshaft is fitted into and fixed to the ring-type fixed base. Effect of the Invention

[0010] As a result, the pedaling force detection mechanism in the electrically assisted bicycle according to the present invention achieves the object of providing assist power in a reliable manner in response to changes in pedaling force. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view of a pedaling force detection mechanism, a crankshaft, an assist power unit, and an axle box according to a specific embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of a pedaling force detection mechanism, a crankshaft, an assist power unit, and an axle box according to a specific embodiment of the present invention. [Diagram 3] FIG. 1 is an exploded perspective view of a force deflection portion, a main thrust stop bearing, and a strain detection unit according to a specific embodiment of the present invention. [Figure 4] FIG. 2 is an exploded perspective view of a force deflection portion, a main thrust stop bearing, and a strain detection unit according to a specific embodiment of the present invention. [Diagram 5] FIG. 1 is a perspective view of a main transmission gear according to a specific embodiment of the present invention. [Figure 6] FIG. 2 is a perspective view of a main transmission gear according to a specific embodiment of the present invention. [Figure 7] FIG. 1 is an assembled perspective view of a pedaling force detection mechanism, a crankshaft, an assist power unit, and an axle box according to a specific embodiment of the present invention. [Figure 8] FIG. 2 is an assembled perspective view of a pedaling force detection mechanism, a crankshaft, an assist power unit, and an axle box according to a specific embodiment of the present invention. [Figure 9] FIG. 8 is a vertical cross-sectional view of the crankshaft of FIG. [Figure 10] FIG. 13 is a reference diagram showing axial strain clearance according to a specific embodiment of the present invention. [Figure 11] FIG. 1 is a perspective view of a ring-type fixed base according to a specific embodiment of the invention. [Figure 12] FIG. 2 is a perspective view of a ring-type fixed base according to a specific embodiment of the invention. [Figure 13] 10 is a reference diagram showing the results of a comparison of torque between a conventional pedal force detection mechanism and the pedal force detection mechanism of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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] 1 to 10, the present invention relates to a pedaling force detection mechanism for an electrically assisted bicycle that is suitable for being housed in an axle box 5 of an electrically assisted bicycle so as to be disposed 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-type cover body 512 that covers the positioning groove body 511. The crankshaft 20 is installed by penetrating the ring-type cover body 512 of the first axle box 51, the positioning groove body 511, and the second axle box 52. The axle box 5 may be an axle box of 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. The assist power unit 3 may be a different type of assist power device.

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

[0016] The main thrust stop bearing 13 abuts against the foot force diverting portion 1 to transmit the diverted foot force F. The main thrust stop bearing 13 may abut against a back ring surface 121 of a driven end cam 12 of the foot force diverting portion 1, or against another foot force diverting mechanism, as described in TWI769802, to transmit the diverted foot force F.

[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 on the outside of the driven end cam 12 of the tread force deflection unit 1, abuts on 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 stop 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 is provided between the main thrust stop bearing 13 and the support ring base 17 by having a ring top surface 151 contact the main thrust stop bearing 13 and a ring bottom surface 152 contact the support ring base 17. The strain gauge 16 is provided on the outer ring surface of the elastic ring base 15 and is communicatively connected to the assist power unit 3 and is connected to a 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 a positioning groove body 511 of the first axle box 51 and the second axle box 52. The crankshaft 20 is connected to the main transmission gear 21 having a main gear 211, an inscribed ring body 210, and an circumscribed ring body 212 by penetrating the crankshaft 20. The inscribed ring body 210 is integrally formed on the inside of the main gear 211, and an inner bearing 217 is provided between the inscribed ring body 210 and the main gear 211 and the crankshaft 20. The circumscribed ring body 212 is fixed to the outside of the main gear 211, and an outer bearing 218 is provided between the circumscribed ring body 212 and the second axle box 52, penetrating the second axle box 52.

[0020] The axial bolt grooves 2121 of the circumscribing ring 212 may be connected to a chain ring (not shown). The axial bolt grooves 122 on the outer ends of the driven end cams 12 of the force deflection unit 1 are operatively connected to the axial bolt grooves 2101 on the ends of the inscribed ring 210 to rotate the driven end cams 12 of the force deflection unit 1 synchronously with the inscribed ring 210.

[0021] The support ring base 17, in which an axial active clearance 7 having a magnitude equal to or greater than the axial strain clearance 6 is formed between the axial bolt grooves 122 and the inscribed ring body 210, may be provided outside a portion where the driven end face cam 12 and the inscribed ring body 210 are connected. The inscribed ring body 210 may be provided penetrating a bottom portion of a positioning groove body 511 of the first axle box 51 so as to be operatively connected to the driven end face cam 12.

[0022] As described above, when the crankshaft 20 of the pedaling force detection mechanism in the electric assisted bicycle of the present invention receives the pedaling force F transmitted from the rider via the pedal (not shown) and the crank (not shown), the driving end cam 11 rotates in one direction in conjunction with the one-way ratchet socket 10, thereby transmitting the pedaling force F.

[0023] Thereafter, the driven end cam 12 is rotated in conjunction with the driving end cam 11, and is pushed and moved in the axial direction of the crankshaft 20 by the driving end cam 11, so that the pedaling force F is converted into the axial direction of the crankshaft 20. When the driven end cam 12 moves in the axial direction of the crankshaft 20, it presses against the main thrust stop bearing 13, causing the main thrust stop bearing 13 to be pressed 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 part 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 a strain and a voltage change according to the deformation of the elastic ring base 15. Then, the torque can be calculated from the voltage change, and further, the torque due to the pedaling force F can be detected by the strain gauge 16. When the magnitude of the torque due to the pedaling force F is equal to or greater than a predetermined torque, the assist power source 31 outputs the assist power to the main gear 211 through the first reduction gear 32 and the second reduction gear 33, thereby enabling the rider to ride the bicycle comfortably and with less effort.

[0025] Furthermore, when the elastic ring base 15 deforms, the strain clearance 6 exists between the front part of the support ring base 17 and the main thrust stop bearing 13. Therefore, if the deformation amount of the elastic ring base 15 exceeds the strain clearance 6, the support ring base 17 braces the main thrust stop bearing 13 to prevent the elastic ring base 15 from being excessively deformed by the main thrust stop bearing 13 and becoming permanently deformed.

[0026] Furthermore, when the driving end cam 11 in the pedal force deflection section 1 pushes and moves the driven end cam 12 toward the crankshaft 20, there is an axial active clearance 7 between the driven end cam 12 of the pedal force deflection section 1 and the inscribed ring body 210, the magnitude of which is greater than or equal to the axial strain clearance 6. Therefore, the driven end cam 12 moves freely in the axial direction during the detection process of the strain gauge 16, thereby allowing the elastic ring base 15 to deform accurately, and therefore the torque due to the pedal force F can be accurately detected by the strain gauge 16.

[0027] In addition, since the inscribed ring body 210 is integrally molded on the inside of the main gear 211, during assembly, it is directly and operably connected to the driven end face cam 12 of the pedal force turning portion 1, thereby improving the ease of assembly and simplifying the processing process of the main transmission gear 21.

[0028] As shown in Fig. 13, the pedaling force detection mechanism according to the present invention can accurately detect whether or not a pedaling force is being input, and therefore has a higher discrimination degree than the conventional pedaling force detection mechanism. Also, the pedaling force detection mechanism according to the present invention can detect a stronger pedaling force, and therefore has a wider detection range than the conventional pedaling force detection mechanism.

[0029] 9, in one embodiment of the present invention, the main thrust stop bearing 13 may be a thrust ball bearing, thereby improving the strength and durability of the main thrust stop bearing 13 of the present invention.

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

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

[0032] The second thrust stop bearing 214 is disposed between the main gear 211 and the adjusting nut 215 and abuts thereon, and is disposed within the circumscribing ring body 212 so as to cover the crankshaft 20. The adjusting nut 215 is disposed within the circumscribing ring body 212 and locked to the crankshaft 20. The fixing nut 216 is locked to the crankshaft 20, abuts against the adjusting nut 215, and is disposed within the circumscribing ring body 212. The twisting direction of the fixing nut 216 is opposite to that of the adjusting nut 215.

[0033] As a result, before the assembly of the pedaling force detection mechanism according to the present invention is completed, the adjusting nut 215 is screwed between the crankshaft 20 and the circumscribing ring body 212, and when the strain gauge 16 detects a signal (i.e., the detection start point of the strain gauge 16), the fixing nut 216 is screwed between the crankshaft 20 and the circumscribing ring body 212 to lock the adjusting nut 215 and complete the assembly of the pedaling force detection mechanism according to the present invention. As a result, the pedaling force detection mechanism according to the present invention has excellent assembly workability, and it is possible to check whether the strain gauge 16 is capable of normal operation when assembly is completed.

[0034] 1, 2, 9, 11 and 12, in one embodiment of the present invention, the pedaling force detection mechanism of the present invention may further include a rotation detection unit 19. The rotation detection unit 19 has a sensor 191 (e.g., a magnetic sensor), a ring-shaped magnet 192 (e.g., a Hall sensor magnet), a ring-shaped fixed base 193, a third thrust stop bearing 194 (e.g., a thrust needle roller bearing), and a first bearing 195. The crankshaft 20 is fitted into a fixing hole 1931 of the ring-shaped fixed base 193 and fixed.

[0035] The third thrust stop bearing 194 is between the rear part of the ring-type fixed base 193 and the driving end cam 11 of the tread force deflection unit 1 and abuts them. The first bearing 195 is provided on a ring-type cover 512 of the axle box 5 and covers the front part of the ring-type fixed base 193. The ring-type magnet 192 is provided in a ring-type fixing groove 1932 in the front part of the ring-type fixed base 193. The sensor 191 is provided on the ring-type cover 512 of the axle box 5 so as to sense the ring-type magnet 192.

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

[0037] The present invention has been disclosed by suitable embodiments, but it is clear to those skilled in the art that the above-mentioned embodiments are merely examples of the present invention and do not limit the scope of the present invention. Any modifications or replacements equivalent to the above-mentioned 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. [Explanation of symbols]

[0038] 1. Pedal force turning section 10 One-way ratchet socket 11 Drive end cam 111 Bearings 12 Follower end face cam 121 Back ring surface 122 Axial bolt groove 13 Main thrust bearing 14 Strain sensing unit 15 Elastic ring base 151 Ring top 152 Ring bottom 16 Strain gauge 17 Support Ring Base 171 Support tube 172 Support ring flange 19 Rotation detection unit 191 Sensors 192 Ring Magnet 193 Ring-type fixed base 1931 Fixed hole 1932 Ring-type fixing groove 194 3rd thrust stop bearing 195 First bearing 20 Crankshaft 21 Main transmission gear 210 Inscribed ring body 2101 Axial bolt groove 211 Main gear 212 Circumscribed ring body 2121 Axial bolt groove 213 First thrust stop bearing 214 Second thrust stop bearing 215 Adjustment nut 216 Fixing 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 lid 52 Second axle box 6 Axial Strain Clearance 7 Axial Active Clearance F Pedal force

Claims

1. A pedaling force detection mechanism for an electrically assisted bicycle suitable for being housed in an axle box of the electrically assisted bicycle so as to be disposed on a crankshaft movably mounted on the axle box and connected to an assist power unit, comprising: a pedaling force redirecting unit that transmits a pedaling force from the crankshaft in one direction and redirects the pedaling force in an axial direction of the crankshaft; A main thrust stop bearing abutting the pedal force deflection portion in order to transmit the deflected pedal force; a strain detection unit including: a support ring base provided outside the pedal force deflection portion, abutting against the axle box, and having an axial strain clearance between the support ring base and the main thrust stop bearing; an elastic ring base provided outside the support ring base, abutting between the main thrust stop bearing and the support ring base; and a strain gauge provided on the elastic ring base and communicatively connected to the assist power unit; a main transmission gear having a main gear, an inscribed ring body integrally formed on the inside of the main gear, and an circumscribed ring body fixed to the outside of the main gear, the main transmission gear being movably provided between the crankshaft and the axle box, The pedal force deflection portion rotates synchronously with the inscribed ring body while having an axial active clearance between the inscribed ring body and the pedal force deflection portion. Pedal force detection mechanism for electrically assisted bicycles.

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

3. The support ring base has a support tube and a support ring flange, The support cylinder has one end with the axial strain clearance between it and the main thrust stop bearing, and the other end is fixed to the support ring flange, The support ring flange is disposed between the elastic ring base and the axle box. The pedaling force detection mechanism according to claim 1.

4. 2. The pedaling force detection mechanism as described in claim 1, wherein the main transmission gear has a first thrust stop bearing that abuts against the axle box and the main gear between them, an adjusting nut that is locked to the crankshaft, a second thrust stop bearing that abuts against the main gear and the adjusting nut between them, and a fixed nut that is locked to the crankshaft and abuts against the adjusting nut, and has a twisting direction opposite to that of the adjusting nut.

5. The present invention further includes a rotation detection unit having a ring-type fixed base, a ring-type magnet provided on the ring-type fixed base, a sensor provided on the axle box to detect the ring-type magnet, a third thrust stop bearing between the ring-type fixed base and the pedal force turning portion and abutting the third thrust stop bearing, and a first bearing provided between the axle box and the ring-type fixed base, The crankshaft is fitted and fixed to the ring-shaped fixed base. The pedaling force detection mechanism according to claim 1.

Images