Middle shaft treading force detection mechanism based on middle shaft radial strain tension detection

Abstract

The invention discloses a center shaft treading force detection mechanism based on center shaft radial strain tension detection, which comprises a center shaft which penetrates through two ends in a five-way pipe and is used for mounting a crank, and a chain wheel is fixed at one end of the center shaft and is connected with a chain wheel of a rear wheel through a chain; the center shaft is supported in the bowl piece through a center shaft bearing, the end, close to the center shaft fixing crankset, of the bowl piece extends out of the bottom bracket and is provided with an expanded bowl opening, an eccentric ring is embedded in the bowl piece, and an inner ring of the eccentric ring is rotationally assembled on the center shaft through an eccentric ring bearing; the center of the outer ring is eccentrically arranged relative to the axis of the middle shaft, a spring piece fixed to the eccentric ring and the bowl piece is further embedded in the bowl opening, a strain gauge is attached to the spring piece, radial tension transmitted to the middle shaft through the chain wheel by the chain is used for driving the eccentric ring to rotate relative to the center of the eccentric ring, and the eccentric ring drives the spring piece to generate micro deformation. And the strain gauge induces to output a treading force signal. According to the mechanism, the pedal force detection precision is higher, the problem of false detection of the strain gauges is solved, the structure is simpler, and assembly is easier.

Description

Technical Field

[0001] The invention relates to a middle shaft pedaling force detection mechanism based on middle shaft radial strain tension detection. Background Art

[0002] Electric bicycles are usually equipped with a central axis pedal force detection mechanism, which is used to detect the pedal force signal in real time, and accurately determine the rider's riding status (light pedaling or heavy pedaling) based on the pedal force signal, so as to drive the motor to adjust the power output. As we all know, since the most direct way to measure the central axis pedal force is to measure the torque or bending moment of the central axis, the central axis pedal force detection mechanism commonly used in the market currently directly attaches strain gauges on the central axis to detect its torque or bending moment. However, in long-term practical use, this detection mechanism has the following problems: 1. There are many interference factors on the force on the middle axis, which greatly affects the detection accuracy of the pedal force; In theory, when a person steps on the pedals, the pedal force is transmitted to the middle shaft through the crank, which generates torque on the middle shaft. However, in reality, the middle shaft is affected by the radial tension transmitted by the chain because the sprocket on it is affected by the radial tension transmitted by the chain, which will offset part of the torque generated by the pedal force, resulting in a reduction in the accuracy of the torque signal detected by the strain gauge.

[0003] 2. Since the strain gauge is directly fixed on the rotating central axis, its signal output cannot be directly led out using a direct signal line, but can only be led out using the wireless induction method of the internal and external coils. Since the wireless induction method of the internal and external coils itself has transmission loss and the signal is susceptible to interference, the output strength and accuracy of the signal are far inferior to the output method of direct connection of the signal line, which leads to a further reduction in the accuracy and reliability of the final pedaling force detection data.

[0004] 3. The torque signal is transmitted by wireless induction of internal and external coils. Both the internal and external coils must be installed deep inside the five-way tube and occupy the internal space of the five-way tube, which makes the radial size of the mechanism larger. In addition, corresponding brackets are required to fix the PCB board of the coil. The structure is complex, with many parts, and assembly, maintenance and disassembly are very cumbersome and inconvenient, resulting in low production efficiency and high maintenance costs. Summary of the invention

[0005] The purpose of the present invention is to provide a central axis pedaling force detection mechanism based on central axis radial strain tension detection to address the shortcomings of the existing central axis pedaling force detection mechanism mentioned in the background technology. The central axis pedaling force detection mechanism not only has higher pedaling force detection accuracy and eliminates the problem of strain gauge misdetection, but also has a simpler structure and is easier to assemble.

[0006] The technical solution of the present invention is: a middle shaft pedaling force detection mechanism based on middle shaft radial strain tension detection, comprising a middle shaft that is penetrated at both ends of a five-way tube for mounting cranks, one end of the middle shaft is also fixed with a toothed disc, and the toothed disc is connected to a sprocket on a rear wheel of an electric bicycle through a chain; it is characterized in that it also includes a bowl piece that is penetrated in the five-way tube, the middle shaft is supported by a middle shaft bearing and is arranged in the bowl piece, an end of the bowl piece that is close to the middle shaft fixing toothed disc extends out of the five-way tube and is provided with an enlarged bowl mouth, an eccentric ring is embedded in the bowl mouth, the inner ring of the eccentric ring is rotatably assembled on the middle shaft via an eccentric ring bearing, the center of the outer ring of the eccentric ring is eccentrically arranged relative to the axis of the middle shaft, a spring sheet that is respectively fixed to the eccentric ring and the bowl piece is also embedded in the bowl mouth, a strain gauge is attached to the spring sheet, the radial tension transmitted to the middle shaft by the chain through the toothed disc is used to drive the eccentric ring to rotate relative to the center of the eccentric ring, the eccentric ring drives the spring sheet to produce micro-deformation, so that the strain gauge senses the micro-deformation to output a pedaling force signal.

[0007] Furthermore, the eccentric ring in the present invention is fixed to the spring sheet by a pin or a screw, or a boss is protruding and fixed on the eccentric ring, and the boss cooperates with a connecting hole provided on the spring sheet to fix the spring sheet, or a connecting hole is provided on the eccentric ring, which cooperates with a boss protruding and fixed on the spring sheet to fix the spring sheet.

[0008] Furthermore, the spring sheet in the present invention is fixed to the bowl member by a plurality of locking screws, and a pressure cover is fixed on the bowl mouth for covering and axially compressing the spring sheet, and a signal processing PCB board electrically connected to the strain gauge is provided in the pressure cover, and the lead wires of the signal processing PCB board are led out through a lead wire port provided on the pressure cover.

[0009] Furthermore, the expanded diameter bowl mouth of the present invention has its rear wall tightly pressed against the outer wall of one end of the five-way tube, and also includes a locking nut. The end of the bowl piece not provided with the bowl mouth extends out from the other end of the five-way tube, and a thread is formed on its outer periphery for threading the locking nut and pressing it against the outer wall of this end of the five-way tube. The locking nut cooperates with the expanded diameter bowl mouth to axially lock the bowl piece on the five-way tube.

[0010] Furthermore, the eccentric ring bearing in the present invention is a stamped outer ring needle roller bearing.

[0011] Furthermore, the bowl piece in the present invention is provided with an inner step at one end other than the bowl mouth, and a corresponding shoulder is formed on the central axis, the central axis bearing is disposed between the inner step and the shoulder, and the bowl piece is also embedded with an outer retaining ring that cooperates with the inner step to clamp the central axis bearing, and an inner retaining ring that cooperates with the shoulder to clamp the central axis bearing.

[0012] Furthermore, the eccentric ring bearing in the present invention is integrally formed with the eccentric ring inner ring.

[0013] Furthermore, in the present invention, a lubricating bearing is embedded between the outer ring of the eccentric ring and the inner circumference of the bowl mouth to reduce the rotational resistance of the eccentric ring.

[0014] The working principle of the present invention is as follows: As in conventional technology, pedals are fixed to the cranks at both ends of the middle shaft. The lead-out wires of the signal processing PCB board are finally electrically connected to the controller of the electric bicycle.

[0015] When riding, the pedal force of a person will be transmitted to the rear wheel (sprocket) through the toothed disc and chain. Under the action of the reaction force, the chain will give the middle axis a radial tension pointing to the rear wheel. Under the action of this radial tension, the eccentric ring tends to rotate around its own center. At this time, the spring sheet radially fixed to the eccentric ring under the fixed action of the fixed point will be pulled to produce a small deformation, which will be sensed by the strain gauge. The strain gauge will generate a signal change and transmit it to the signal processing PCB board. The signal processing PCB board will process the signal change and output a torque signal to control the speed of the motor output of the electric bicycle. Depending on the pedal force of the person, the torque of the eccentric ring and the deformation of the spring sheet will change accordingly, and the signal change transmitted by the strain gauge will also be different, thereby achieving the function of accurately detecting the pedal force.

[0016] The advantages of the present invention are: The present invention not only has higher detection accuracy of pedal force, but also eliminates the problem of strain gauge misdetection, and has a simpler structure and is easier to assemble. The specific advantages are as follows: 1. In the structural design of the present invention, the pedaling force of a person is transmitted to the rear wheel (sprocket) through the chainring and the chain. Under the action of the reaction force, the chain will give the middle axis a radial pulling force pointing to the rear wheel. The eccentric ring only generates torque under the action of this radial pulling force and triggers the spring sheet to deform so that the strain gauge outputs a torque signal. Therefore, the detection and acquisition of its torque signal eliminates many interference factors and has higher detection accuracy.

[0017] 2. In the structural design of the present invention, the strain gauge and the signal processing PCB board will not rotate with the central axis. Therefore, the signal of the strain gauge can be directly connected to the signal processing PCB board by wires without the need to use the wireless induction method of the internal and external coils to lead out. Therefore, there is no transmission loss and signal susceptibility to interference problems existing in the wireless induction method of the internal and external coils, so that the output strength and accuracy of the signal are qualitatively improved, thereby ensuring the accuracy and reliability of the final torque detection data.

[0018] 3. In the structural design of the present invention, since the method of extracting the strain gauge signal data of the wireless induction of the inner and outer coils is eliminated, not only the components including the inner and outer coils, the corresponding brackets, etc. are saved, but also since there is no need to install deeply inside the bottom bracket tube, and the volume space inside the bottom bracket tube is not occupied, the radial dimension of the entire middle axis pedaling force detection mechanism is reduced, and the structure is simpler and more compact, and assembly, maintenance and disassembly are extremely convenient, which effectively improves production efficiency and reduces maintenance costs.

[0019] 4. The lead wires of the signal processing PCB board in the present invention are directly led out from the lead wire hole of the gland on the outermost side of the bowl mouth, without the need to route the wires through the grooves on the inner side of the five-way pipe as in the prior art. The lead-out of the signal wires is very smooth and convenient, which is convenient for subsequent wiring and maintenance.

[0020] 5. The eccentric ring, spring sheet and pressure cover in the present invention are integrated and fixed in the bowl mouth at one end of the bowl member, which is easy to assemble and can be modularly produced together with the bowl member. It is small and light, has a compact structure, is easy to adapt and install with various five-way pipes, and helps to improve the neatness and aesthetics of the appearance of the electric bicycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the overall three-dimensional structure of an embodiment of the present invention; Figure 2 for Figure 1 Axial section of the (crank and chainring removed); Figure 3 for Figure 2 Right view of; Figure 4 for Figure 3 View after removing the gland; Figure 5 for Figure 4 View after spring leaf is removed; Figure 6 for Figure 1 Schematic diagram of the separate three-dimensional structure of the middle eccentric ring; Figure 7 is an axial cross-sectional view of another embodiment of the present invention (without the crank and the toothed disc); Figure 8 for Figure 7 Right view of; Fig. 9 for Figure 7 View after removing the gland; Fig.10 for Figure 7 View after spring leaf is removed; Fig.11 for Figure 7A schematic diagram of the three-dimensional structure of an eccentric ring with an eccentric ring bearing integrated therein.

[0022] Among them: 1. bottom bracket; 2. crank; 3. bottom bracket; 3a. shoulder; O1. axis; 4. chainring; 5. chain; 6. sprocket; 7. bowl; 7a. inner step; 701. bowl mouth; 8. bottom bracket bearing; 9. eccentric ring; O2. center; A. fixing point; 10. eccentric ring bearing; 11. spring sheet; 12. strain gauge; 13. pin; 14. gland; 14a. lead-out port; 15. signal processing PCB board; 16. locking nut; 17. outer retaining ring; 18. inner retaining ring; 19. locking screw; 20. lubricating bearing. DETAILED DESCRIPTION

[0023] Example 1: Combined with Figure 1 to Figure 6 The specific implementation of the central axis pedal force detection mechanism based on central axis radial strain tension detection provided by the present invention is described as follows: This middle axle pedaling force detection mechanism based on middle axle radial strain tension detection is the same as conventional technology, with a middle axle 3 passing through both ends of a five-way tube 1 for mounting cranks 2, one end of the middle axle 3 is also fixed to a chainring 4 located on the inner side of the crank 2 at that end, and the chainring 4 is connected to a sprocket 6 on the rear wheel of the automatic bicycle through a chain 5.

[0024] The core improvement of the present invention is that: a bowl piece 7 is inserted into the bottom bracket tube 1, and the middle shaft 3 is supported by the middle shaft bearing 8 and arranged in the bowl piece 7. The end of the bowl piece 7 close to the middle shaft 3 fixing the tooth plate 4 extends out of the bottom bracket tube 1 to set an enlarged bowl mouth 701, and an eccentric ring 9 (the centers of the inner and outer rings do not overlap) is embedded in the bowl mouth 701. The inner ring of the eccentric ring 9 is rotatably assembled on the middle shaft 3 via the eccentric ring bearing 10, so that the center of the inner ring of the eccentric ring 9 overlaps with the axis O1 of the middle shaft 3, and the center O2 of the outer ring is eccentrically arranged relative to the axis O1 of the middle shaft 3 (does not overlap), as shown in detail. Figure 5 The eccentric ring 9 is provided with a fixed point A, which is radially fixed to a spring sheet 11 which is also embedded in the bowl mouth 701 through a pin 13. At the same time, the lower part of the spring sheet 11 is fixed to the bottom wall of the bowl mouth 701 of the bowl member 7 by three locking screws 19 (axially nailed). Figure 2 A strain gauge 12 is attached to the spring sheet 11, and the radial tension transmitted from the chain 5 to the middle shaft 3 through the toothed disc 4 is used to drive the eccentric ring 9 to rotate relative to the center O2 of the eccentric ring 9, and the eccentric ring 9 drives the spring sheet 11 to produce a micro deformation, so that the strain gauge 12 senses the micro deformation to output a pedaling force signal.

[0025] And specifically combined Figure 2 and Figure 3As shown, in this embodiment, a pressure cover 14 for covering and axially pressing the spring sheet 11 is also fixed to the inner circumference of the bowl mouth 701, and a hook (omitted in the figure) is provided on the outer ring of the pressure cover 14, which cooperates with a slot (omitted in the figure) provided on the inner circumference of the bowl mouth 701 to complete the fixing. A signal processing PCB board 15 electrically connected to the strain gauge 12 is provided in the pressure cover 14, and the lead wires of the signal processing PCB board 15 are led out through the lead wire port 14a provided on the pressure cover 14.

[0026] Still like Figure 2 As shown, the expanded diameter bowl mouth 701 in this embodiment has its rear wall pressed against the outer wall of one end of the five-way tube 1, and also includes a locking nut 16. The end of the bowl piece 7 not provided with the bowl mouth 701 extends out of the other end of the five-way tube 1, and a thread is formed on its outer periphery for screwing the locking nut 16 and pressing it against the outer wall of this end of the five-way tube 1. The locking nut 16 cooperates with the expanded diameter bowl mouth 701 to axially lock the bowl piece 7 on the five-way tube 1.

[0027] The eccentric ring bearing 10 in this embodiment is a stamped outer ring needle roller bearing.

[0028] In this embodiment, the central axis bearing 8 is sleeved near the end of the central axis 3 that is not fixed with the chainring 4. The end of the bowl 7 that is not provided with the bowl mouth 701 is provided with an inner step 7a, and a corresponding shaft shoulder 3a is formed on the central axis 3. The central axis bearing 8 is disposed between the inner step 7a and the shaft shoulder 3a, and the bowl 7 is also embedded with an outer retaining ring 17 that cooperates with the inner step 7a to clamp the central axis bearing 8, and an inner retaining ring 18 that cooperates with the shaft shoulder 3a to clamp the central axis bearing 8.

[0029] And, combined with Figure 2~Figure 5 As shown, in this embodiment, the fixed point A, the center O2 of the eccentric ring 9 and the axis O1 of the central axis 3 are arranged in sequence from top to bottom, and at the same time, the fixed point A, the center O2 of the eccentric ring 9 and the axis O1 of the central axis 3 are connected in a straight line and point to the ground.

[0030] Moreover, in this embodiment, the inner ring of the eccentric ring 9 and the eccentric ring bearing 10 are designed to be separated. After the eccentric ring bearing 10 is removed, the three-dimensional structure of the separate eccentric ring 9 is as follows: Figure 6 shown.

[0031] The working principle of the present invention is as follows: As in conventional technology, pedals (omitted in the figure) are fixed to the cranks 2 at both ends of the middle shaft 3. The lead wires of the signal processing PCB board 15 are finally electrically connected to the controller of the electric bicycle.

[0032] During riding, the pedaling force of a person will be transmitted to the rear wheel (sprocket 6) through the chainring 4 and the chain 5. Under the action of the reaction force, the chain 5 will give the middle axis 3 a radial pulling force directed to the rear wheel. Under the action of this radial pulling force, the eccentric ring 9 tends to rotate around its own center O2. At this time, the spring sheet 11 radially fixed to the eccentric ring 9 will be pulled to produce a small deformation under the fixing action of the fixed point A pin 13, which will be sensed by the strain gauge 12. The strain gauge 12 will generate a signal change and transmit it to the signal processing PCB board 15. The signal processing PCB board 15 will process the signal change and output a torque signal to control the speed of the motor output of the electric bicycle. According to the different pedaling force of the person, the torsion of the eccentric ring 9 and the deformation of the spring sheet 11 will change accordingly, and the signal change transmitted by the strain gauge 12 will also be different, thereby achieving the function of accurately detecting the pedaling force.

[0033] For the above structural design of the present invention, the pedaling force of a person is transmitted to the rear wheel (sprocket 6) through the chainring 4 and the chain 5. Under the action of the reaction force, the chain 5 will give the middle shaft 3 a radial pulling force pointing to the rear wheel. The eccentric ring 9 only generates torque under the action of this radial pulling force and triggers the spring sheet 11 to deform so that the strain gauge 12 outputs a torque signal. Therefore, the detection and acquisition of its torque signal eliminates many interference factors and has higher detection accuracy.

[0034] Furthermore, since the strain gauge 12 and the signal processing PCB board 15 will not rotate with the central axis 3, the signal of the strain gauge 12 can be directly connected to the signal processing PCB board 15 by wires without the need to use the wireless induction method of the internal and external coils to lead out. Therefore, there is no transmission loss and signal susceptibility to interference problems existing in the wireless induction method of the internal and external coils, so that the output strength and accuracy of the signal are qualitatively improved, thereby ensuring the accuracy and reliability of the final torque detection data.

[0035] Furthermore, since the signal data extraction method of the strain gauge 12 for wireless induction of the inner and outer coils is eliminated, not only the components including the inner and outer coils, the corresponding brackets, etc. are saved, but also since there is no need to install deeply inside the bottom bracket tube 1, and the volume space inside the bottom bracket tube 1 is not occupied, the radial dimension of the entire middle axis pedaling force detection mechanism is reduced, and the structure is simpler and more compact, and assembly, maintenance and disassembly are extremely convenient, which effectively improves production efficiency while reducing maintenance costs.

[0036] Furthermore, since the lead wires of the signal processing PCB board 15 are directly led out from the lead wire hole 14a of the outermost pressure cover 14 of the bowl mouth 701, there is no need to route the wires through the grooves on the inner side of the five-way tube 1 as in the prior art. The lead-out of the signal wires is very smooth and convenient, which is convenient for subsequent wiring and maintenance.

[0037] Furthermore, since the eccentric ring 9, the spring sheet 11 and the pressure cover 14 are all integrated and fixed in the bowl mouth 701 at one end of the bowl member 7, they are easy to assemble and can be modularly produced together with the bowl member 7. They are compact and light, have a compact structure, and are easy to adapt and install with various types of five-way pipes 1, and help to improve the neatness and aesthetics of the appearance of the electric bicycle.

[0038] Example 2: Combination Figure 7-Figure 11 The figure shows another embodiment of the central axis pedaling force detection mechanism based on the central axis radial strain tension detection of the present invention. Its overall structure is basically the same as that of the first embodiment, and it also has a central axis 3 that is inserted through the two ends of the five-way tube 1 for mounting the crank 2. One end of the central axis 3 is also fixed to the chain plate 4 located inside the crank 2 at this end. The chain plate 4 is connected to the sprocket 6 on the rear wheel of the automatic bicycle through a chain 5. A bowl piece 7 is inserted through the five-way tube 1. The central axis 3 is supported by the central axis bearing 8 and is arranged in the bowl piece 7. The end of the bowl piece 7 that is close to the central axis 3 and fixes the chain plate 4 extends out of the five-way tube 1 to set an enlarged bowl mouth 701. An eccentric ring 9 is embedded in the bowl mouth 701. The inner ring of the eccentric ring 9 is also rotatably assembled on the central axis 3 via the eccentric ring bearing 10, so that the center of the inner ring of the eccentric ring 9 overlaps with the axis O1 of the central axis 3, while the center O2 of the outer ring is eccentrically arranged relative to the axis O1 of the central axis 3 (not overlapping). See details. Figure 5 As shown, the line connecting the two points to the ground.

[0039] Further combining Figure 7 and Fig.11 As shown, the difference between this embodiment and the first embodiment in structure is that the inner ring of the eccentric ring 9 is integrally formed with the eccentric ring bearing 10, and the eccentric ring bearing 10 is also a stamped outer ring needle bearing. At the same time, a lubricating bearing 20 is embedded between the outer ring of the eccentric ring 9 and the inner circumference of the bowl mouth 701 to reduce the rotation resistance of the eccentric ring.

[0040] In addition, similar to the first embodiment, a fixing point A is also provided on the eccentric ring 9 in this embodiment, and the fixing point A is radially fixed to the spring sheet 11 which is also embedded in the bowl mouth 701 through a pin 13. At the same time, the lower part of the spring sheet 11 is fixed to the bottom wall of the bowl mouth 701 of the bowl member 7 by three locking screws 19 (axially nailed). Figure 7 A strain gauge 12 is attached to the spring sheet 11, and the radial tension transmitted from the chain 5 to the middle shaft 3 through the toothed disc 4 is used to drive the eccentric ring 9 to rotate relative to the center O2 of the eccentric ring 9, and the eccentric ring 9 drives the spring sheet 11 to produce a micro deformation, so that the strain gauge 12 senses the micro deformation to output a pedaling force signal.

[0041] And specifically combined Figure 7 and Figure 8As shown, in this embodiment, the inner periphery of the bowl mouth 701 is also fixed with a gland 14 for covering and axially pressing the spring sheet 11. The difference from the first embodiment is that the gland 14 is sleeved on the bowl mouth 701, and a hook (omitted in the figure) is provided on the inner periphery of the gland 14, which cooperates with a groove (omitted in the figure) provided on the outer periphery of the bowl mouth 701 to complete the fixing. A signal processing PCB board 15 electrically connected to the strain gauge 12 is provided in the gland 14, and the lead wires of the signal processing PCB board 15 are led out through the lead wire port 14a provided on the gland 14.

[0042] Still like Figure 7 As shown, the expanded diameter bowl mouth 701 in this embodiment has its rear wall pressed against the outer wall of one end of the five-way tube 1, and also includes a locking nut 16. The end of the bowl piece 7 not provided with the bowl mouth 701 extends out of the other end of the five-way tube 1, and a thread is formed on its outer periphery for screwing the locking nut 16 and pressing it against the outer wall of this end of the five-way tube 1. The locking nut 16 cooperates with the expanded diameter bowl mouth 701 to axially lock the bowl piece 7 on the five-way tube 1.

[0043] In this embodiment, the central axis bearing 8 is sleeved near the end of the central axis 3 that is not fixed with the chainring 4. The end of the bowl 7 that is not provided with the bowl mouth 701 is provided with an inner step 7a, and a corresponding shaft shoulder 3a is formed on the central axis 3. The central axis bearing 8 is disposed between the inner step 7a and the shaft shoulder 3a, and the bowl 7 is also embedded with an outer retaining ring 17 that cooperates with the inner step 7a to clamp the central axis bearing 8, and an inner retaining ring 18 that cooperates with the shaft shoulder 3a to clamp the central axis bearing 8.

[0044] And, combined with Figure 7~Figure 10 As shown, in this embodiment, the fixed point A, the center O2 of the eccentric ring 9 and the axis O1 of the central axis 3 are arranged in sequence from top to bottom, and at the same time, the fixed point A, the center O2 of the eccentric ring 9 and the axis O1 of the central axis 3 are connected in a straight line and point to the ground.

[0045] Compared with Example 1, the eccentric ring 9 and the inner eccentric ring bearing 10 are designed as one piece in this embodiment, which is not only compact but also very convenient for assembly and disassembly. In addition, the introduction of the lubricating bearing 20 on the outer ring of the eccentric ring 9 also improves the working reliability and sensitivity of the eccentric ring 9. The basic working principle and implementation effect of this embodiment can be found in the description of Example 1, which will not be repeated here.

[0046] Of course, the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any modifications made according to the spirit of the main technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A middle axle pedaling force detection mechanism based on middle axle radial strain tension detection, comprising a middle axle (3) which is inserted into a bottom bracket tube (1) at both ends and is used to mount a crank (2), a chain plate (4) is fixed to one end of the middle axle (3), and the chain plate (4) is connected to a sprocket (6) on the rear wheel of an automatic bicycle through a chain (5); characterized in that It also includes a bowl member (7) inserted into the five-way tube (1), the middle shaft (3) is supported by the middle shaft bearing (8) and is arranged in the bowl member (7), one end of the bowl member (7) close to the middle shaft (3) fixing the tooth plate (4) extends out of the five-way tube (1) to be provided with an enlarged bowl mouth (701), an eccentric ring (9) is embedded in the bowl mouth (701), the inner ring of the eccentric ring (9) is rotatably assembled on the middle shaft (3) via an eccentric ring bearing (10), and the center (O2) of the outer ring of the eccentric ring (9) is relative to the center of the middle shaft (3). The axis (O1) is eccentrically arranged, and a spring sheet (11) is embedded in the bowl mouth (701) and is fixed to the eccentric ring (9) and the bowl member (7) respectively. A strain gauge (12) is attached to the spring sheet (11). The radial tension transmitted to the middle shaft (3) by the chain (5) through the toothed disc (4) is used to drive the eccentric ring (9) to rotate relative to the center (O2) of the eccentric ring (9). The eccentric ring (9) drives the spring sheet (11) to produce a micro-deformation, so that the strain gauge (12) senses the micro-deformation to output a pedaling force signal.

2. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1 is characterized in that The eccentric ring (9) is fixed to the spring sheet (11) via a pin (13) or a screw, or a boss is protruding and fixed on the eccentric ring (9), and the boss cooperates with a connecting hole provided on the spring sheet (11) to fix the spring sheet (11), or a connecting hole is provided on the eccentric ring (9), and the connecting hole cooperates with a boss protruding and fixed on the spring sheet (11) to fix the spring sheet (11).

3. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1 is characterized in that The spring sheet (11) is fixed to the bowl member (7) via a plurality of locking screws (19), and a pressure cover (14) is fixed to the bowl mouth (701) for covering and axially pressing the spring sheet (11). A signal processing PCB board (15) electrically connected to the strain gauge (12) is arranged in the pressure cover (14), and lead wires of the signal processing PCB board (15) are led out via a lead wire opening (14a) arranged on the pressure cover (14).

4. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1, characterized in that The expanded diameter bowl mouth (701) has a rear wall which is tightly abutted against an outer wall of one end of the five-way tube (1), and further comprises a locking nut (16); an end of the bowl member (7) not provided with the bowl mouth (701) extends out of the other end of the five-way tube (1), and a thread is formed on its outer periphery for screwing the locking nut (16) and abutting against the outer wall of the end of the five-way tube (1); the locking nut (16) cooperates with the expanded diameter bowl mouth (701) to axially lock the bowl member (7) on the five-way tube (1).

5. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1, characterized in that The eccentric ring bearing (10) is a stamped outer ring needle roller bearing.

6. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1, characterized in that An inner step (7a) is provided at one end of the bowl member (7) not provided with the bowl mouth (701), and a shaft shoulder (3a) is formed correspondingly on the middle shaft (3); the middle shaft bearing (8) is disposed between the inner step (7a) and the shaft shoulder (3a); and an outer retaining ring (17) cooperating with the inner step (7a) to clamp the middle shaft bearing (8) and an inner retaining ring (18) cooperating with the shaft shoulder (3a) to clamp the middle shaft bearing (8) are also embedded in the bowl member (7).

7. The central axis pedal force detection mechanism based on central axis radial strain tension detection according to claim 1, characterized in that The eccentric ring bearing (10) is integrally formed on the inner ring of the eccentric ring (9).

8. The central axis pedaling force detection mechanism based on central axis radial strain tension detection according to claim 1 or 7, characterized in that A lubricating bearing (20) is embedded between the outer ring of the eccentric ring (9) and the inner circumference of the bowl mouth (701).

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