Power-assisted motor control system of photoelectric torque sensor

Abstract

The utility model relates to a power-assisted motor control system of a photoelectric torque sensor, which is mounted at pedals of a bicycle, pedal handles are fixed at two ends of a pedal spindle, an outer sleeve is sleeved on the pedal spindle, a power-assisted motor is mounted on a rear wheel of the bicycle, the power-assisted motor is in communication connection with a motor control unit and a battery pack, and an inner sleeve is further arranged between the pedal spindle and the outer sleeve. The torque spring is sleeved and fixed on the pedal shaft; a hanging strip for hooking a spring hook of the torque spring is arranged on the inner side surface of the inner sleeve; a middle hole of the inner light-blocking disc is pressed on the outer side surface of the inner sleeve; when a pedal force is applied, under the action of the torque spring, the inner light blocking disc and the outer pulse disc respectively rotate along with the inner sleeve and the pedal shaft to form a relative displacement angle. The signal board for sending and receiving the photoelectric signals is used for detecting the relative displacement angle and sending the detected signals to the motor control unit of the power assisting motor, intelligent power assisting in the bicycle riding process is achieved, and the riding experience is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of bicycle power-assisted control, in particular to a photoelectric torque sensor power-assisted motor control system. Background Art

[0002] Traditional bicycle power-assist systems usually determine the rider's riding intention by detecting pedal force or rotation speed or acceleration, thereby controlling the output of the power-assist motor. However, these methods are difficult to accurately reflect the force applied by the rider on the pedals, some are too complicated, and some are expensive, which limits their practical applications. Therefore, it is of great significance to develop a simple, cheap, and applicable power-assist motor control system that can accurately detect pedal force and control the speed of the power-assist motor. Utility Model Content

[0003] The purpose of the utility model is to provide a bicycle photoelectric torque sensor power-assisting motor control system, which detects the pedal force through photoelectric code scanning technology, and converts the detection result into a variable signal for controlling the speed of the power-assisting motor, thereby realizing intelligent power-assisting control.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A photoelectric torque sensor power-assisted motor control system comprises a photoelectric torque sensor mechanism, a photoelectric code scanning device, and a power-assisted motor control unit.

[0006] The photoelectric torque sensor mechanism is installed at the five-way joint of the bicycle frame. An outer sleeve is sleeved on the pedal shaft, and an inner sleeve is also arranged between the pedal shaft and the outer sleeve. Bearings are arranged between the pedal shaft and the inner sleeve and between the outer sleeve and the inner sleeve. Through the cooperation of the two sets of bearings, the inner sleeve can rotate simultaneously with the pedal shaft but not synchronously; the sprocket is fixed to the end of the inner sleeve, and the middle part of the sprocket is provided with a hole for the pedal shaft to pass through; a torque spring is designed, which has a semicircular ring in the middle. The semicircular ring is fixed to the pedal shaft with screws. The left and right parts of the torque spring have the same number of turns and opposite rotation directions. Hooks are symmetrically arranged at both ends of the torque spring, and the hooks are hung on the hanging strips on the inner wall of the inner sleeve; pedal handles are fixed at both ends of the pedal shaft, and left and right pedal components are installed on the pedal shaft. A power-assist motor is installed on the rear wheel of the bicycle, and the power-assist motor is connected to the motor control unit and the battery pack.

[0007] The photoelectric code scanning device is arranged on one side of the outer jacket and includes a sensor base and a sensor cover. The sensor base and the sensor cover form a circular cavity. The inner optical disc, the outer pulse disc, and the signal board for sending and receiving photoelectric signals are located in the circular cavity. The sensor base is installed at one end of the outer jacket. The center hole of the inner optical disc is pressed onto the outer side of the inner sleeve; the center hole of the outer pulse disc is pressed onto the pedal shaft. The inner optical disc and the outer pulse disc rotate with the inner sleeve and the pedal shaft respectively. Both the inner optical disc and the outer pulse disc have vertically protruding spokes around the belly of the disc. The belly of the inner optical disc and the outer pulse disc overlap, the spokes overlap, the width of the spokes is the same, and they can slide relative to each other.

[0008] When riding, the pedal force causes the inner sleeve and sprocket to rotate simultaneously with the pedal shaft through the spring hook to drive the bicycle forward; at the same time, the displacement angle of the inner sleeve and sprocket rotation has a certain lag relative to the displacement angle of the pedal shaft, and this lag angle is called the relative displacement angle; when the pedal force reaches a certain value, the screw that installs the spring hits the hanging bar and acts as a limit, the spring no longer increases the torsion, and the relative displacement angle does not change to the maximum value, but the pedal force can still be increased.

[0009] Furthermore, the outer sleeve is welded to the frame, an inner sleeve is mounted on the inner side of the outer sleeve through a pair of bearings at both ends, and a pedal shaft is mounted on the inner side of the inner sleeve through a pair of bearings at both ends.

[0010] Furthermore, there is a semicircular ring in the middle of the torque spring, which is fixed to the pedal shaft with screws. The left and right parts of the torque spring have the same number of turns and opposite rotation directions. Hooks are symmetrically arranged at both ends of the torque spring, and the hooks are hung on the hanging strips on the inner wall of the inner sleeve. When the pedal shaft rotates, the inner sleeve rotates at the same time, and the relative displacement angle between the two is generated under the action of the torque spring.

[0011] Furthermore, the signal board for sending and receiving photoelectric signals is installed on the bottom plate in the cavity formed by the sensor cover and the base; the signal board is provided with two rows of photoelectric tube mounting holes for one synchronization signal and four displacement angle signals, and the hole spacing corresponds to four equal circumferential angles at the center of the pedal shaft; in the middle of the five photoelectric holes, an arc-shaped groove is opened, so that the five photoelectric tube mounting holes are also divided into five pairs of mounting holes; the transmitting photoelectric tube is installed on the far axis side, and the receiving photosensitive triode is installed on the near axis side. When the inner optical disc and the outer pulse disc rotate, their spoke edges can pass through the groove.

[0012] Furthermore, a long arc-shaped waist groove is provided on the spoke edge of the inner optical disc; and five lamp holes with equal angles in two rows, one on top and four on the bottom, are provided on the spoke edge of the outer pulse disc, and the angle is the same as that of the lamp holes of the signal plate.

[0013] Furthermore, when the pedal shaft and the inner sleeve rotate simultaneously, due to the difference in relative displacement angle, the timing of the transmitted light is also different, and the photosensitive transistor at the receiving end of the signal board generates pulse signals with different timings. This code scanning is dynamic. Each code scanning is a code scanning cycle, and it can be designed that there are 2 or 4 code scanning cycles for one pedal rotation.

[0014] Furthermore, the power-assist motor control unit includes a pulse signal latch and readout module, a signal conversion circuit, and a motor speed adjustment module. The pulse latch and readout module includes a latch chip, which receives and latches the electrical pulse signal generated by the photoelectric scanning device under the control of the synchronization signal; the above-mentioned last four-bit pulse signal is read and latched under the control of the highest-bit synchronization pulse; and the corresponding four-bit output signal is always in the readout state, and its value is maintained until the next scanning cycle is updated and read out. The signal conversion includes four output terminals, each of which is connected to a resistor of the same resistance value and is connected to the base of the transistor. The current of the high-level signal is equal, and is added in multiples according to the size of the readout weight. After amplification, the collector of the transistor generates an amplified current of the same relationship. The motor speed adjustment module selects different models of modules according to different models of motors, converts the amplified collector current into the speed adjustment signal and related data of the motor, and completes the overall power-assist motor control function.

[0015] It should be noted that the technologies used in the power-assisted motor control unit can be achieved through commercial procurement, and the electronic control system is not the core innovation of this application.

[0016] Beneficial effects: The utility model accurately detects the pedal force through photoelectric scanning technology, and controls the speed of the rear wheel power-assisting motor according to the detection results, thus realizing intelligent power-assisting control. When the power-assisting reaches the maximum, the torque spring limit is enabled, and the pedal force can still be increased to speed up without damage, so as to meet the needs of special experience; in addition, when the battery is out of power during riding, the rider can still continue riding like riding an ordinary bicycle. Compared with the traditional power-assisting method, the utility model has a higher power-assisting effect and a better riding experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described below in conjunction with the accompanying drawings:

[0018] Figure 1 It is an isometric view of the foot sensor mechanism and the photoelectric code scanning device;

[0019] Figure 2 It is a cross-sectional view of the foot sensor mechanism and the photoelectric code scanning device;

[0020] Figure 3 This is an exploded view of the photoelectric code scanning device;

[0021] Figure 4This is a full display picture of an electric-assisted bicycle;

[0022] Figure 5 This is the schematic diagram of the photoelectric code scanning circuit;

[0023] In the figure: 1-bicycle tripod; 2-sprocket; 3-pedal handle; 4-pedal shaft; 5-outer jacket; 6-torque spring; 7-sensor base; 8-sensor cover; 9-signal board; 10-inner optical disc; 11-outer pulse disc; 12-torque spring fixing screw; 13-analog signal observation window; 14-disc belly; 15-disc spokes; 16-hole through which the shaft passes; 17-hole through which the synchronization signal light passes; 18-hole through which the position signal light passes; 19-inner optical disc mounting hole; 20-long arc waist groove; 21-photoelectric receiving tube mounting hole; 22-base mounting hole; 23-outer pulse disc mounting hole; 24-DC motor; 25-lithium battery pack; 26-latch; 31-motor speed adjustment module; 32-DC motor; 33-lithium battery pack; 34-inner sleeve; 35-outer jacket bearing; 36-inner sleeve bearing; 37-pedal sensor shell; 38-6 wires; DETAILED DESCRIPTION

[0024] Please refer to Figure 1-3 As shown, the utility model discloses a bicycle photoelectric torque sensor power-assisted motor control system. The photoelectric torque sensor mechanism includes a pedal shaft 4, an outer sleeve 5, an inner sleeve 34, and a torque spring 6, wherein the pedal shaft 4, the outer sleeve 5, and the inner sleeve 34 are concentrically arranged with two bearings. These components are placed at the five-way position of the bicycle tripod 1. The pedal handle 3 is fixedly mounted on the pedal shaft 4, and the rider can apply force to the pedal shaft by the left and right pedal handles 3. The torque spring 6 is designed as a symmetrical double-arm structure with a half ring in the middle, which is sleeved on the central surface of the pedal shaft 4 and fastened with screws. The left and right parts of the torque spring have the same number of turns and opposite rotation directions. The sprocket 2 is fixed to the end of the inner sleeve 34 so that the inner sleeve 34 and the sprocket 2 can rotate together. A hanging bar is added to the inner side of the inner sleeve 34. When the rider's pedal rotates, the spring of the torque spring 6 hooks the hanging bar, so that the torque spring is stressed and drives the inner sleeve, sprocket, chain, and rear wheel to rotate together. The greater the pedaling force, the greater the force on the spring, and the greater the spring torsion angle.

[0025] When the spring torque reaches a certain value, the torque spring fixing screw 12 hits the hanging bar, which acts as a limit and drives the sprocket to rotate synchronously. At this time, the displacement angle difference between the shaft and the inner sleeve, that is, the relative displacement angle, remains at the maximum, which also means that the electric power assistance is also at the maximum and remains unchanged. However, the pedaling force can still be increased, and the speed can be artificially increased.

[0026] The key to the design of the photoelectric code scanning device is to convert the relationship between the pedal force and the speed of the rear wheel power-assisted motor into a variable signal. To this end, a set of torque sensors is designed on the outside of the outer jacket 5. The sensor includes a sensor base 7, a sensor cover 8, an inner optical disc 10 and an outer pulse disc 11. The inner optical disc 10 and the outer pulse disc 11 are respectively pressed on the outer side of the inner sleeve 34 and the pedal shaft, and can slide relative to each other in the circular cavity. The inner optical disc 10 and the outer pulse disc 11 do not have friction with the seat and the cover. What we are concerned about is that the pair of discs directly show the relative displacement angle. It can be seen that this relative displacement angle is the relative displacement angle between the inner optical disc and the outer pulse disc. When the pedal force is applied, the two discs will rotate with the inner sleeve and the pedal shaft respectively. Since the relative displacement angle between them will change with the change of the pedal force, the pulse signal generated by the photoelectric code scanning can be used to detect this relative displacement angle to infer the magnitude of the pedal force.

[0027] To achieve this purpose, a signal board 9 of a photoelectric transmitting and receiving device is designed. The signal board is provided with two rows of photoelectric tube mounting holes 18, one in the upper row and four in the lower row. These photoelectric tubes are used to transmit and receive light. A circular arc-shaped groove is provided on the signal board, so that the circular arc spokes of the two code disks can fall into it, thereby ensuring that the photoelectric tube can correctly receive the light. At the same time, the five holes are cut into two halves to become five pairs of concentric holes, with a light-emitting diode installed at one end and a photosensitive triode that receives light installed at the other end.

[0028] When the rider applies pedal force, the inner optical disc 10 and the outer pulse disc 11 rotate relative to each other, causing the holes of the outer pulse disc that are not blocked by the inner optical disc to expose the light emitted by the phototransistor and be received by the photosensitive triode. In this way, the phototube will receive different numbers of light beam signals, thereby generating electrical pulse signals with different weights.

[0029] During the code scanning process, there is a long arc-shaped waist groove 20 every 90° on the spoke edge of the inner blocking optical disc, and each groove can transmit light from up to five phototubes. The spoke edge of the outer pulse disk has 4 pairs of corresponding holes 18 for the signal light to pass through every 90°. As the pedal force changes, the inner blocking optical disc will block part of the light beam, causing the number of light beams received by the phototube to change. This change will be converted into an electrical pulse signal. During this process, the disk spoke rotates 90°, which is called a code scanning cycle. The disk spoke rotates 360°, and one pedal circle goes through 4 code scanning cycles. Of course, it can also be designed as 2 code scanning cycles, which requires implementation based on the effect.

[0030] In a scanning cycle, due to the change of relative displacement angle, the inner light ring blocks part of the light beam. The relative displacement angle is 0, so that all five lights are blocked and the code is scanned in vain; only one synchronous light is scanning, which is gear 0; there is a synchronous light and a light next to it scanning, which is gear 1; ... all four lights next to it are scanning, which is gear 4. The signal combinations read out together with the pulse signal are 10000, 11000, 11100, 11110, 11111. The last four digits are the four-speed pulse adjustment speed signal to be used.

[0031] Please note two important points:

[0032] The displacement angle has reached the maximum. Due to the limit, the relative displacement angle will not increase any further, and the electric power assist is at the maximum. However, it does not prevent the pedaling force from increasing, and the speed can continue to increase.

[0033] If the battery runs out while riding, there is no electric assist, but you can still ride like a normal bike. Even if you press the limit for a long time, it will not damage the bike.

[0034] When the pedal force decreases, the number of lights scanned becomes less and the gear is reduced. This is the whole process of the pedal sensor photoelectric code scanning.

[0035] According to the electric pulse signal generated by the scanning result, the latch chip of the electronic circuit stores the pulses of the lower four bits corresponding to the pedal force under the guidance of the highest bit synchronous pulse. The output end of the latch is always outputting, and the updated data is obtained under the control of the synchronous pulse of the next cycle. Through the current superposition calculation method, it eventually becomes the speed adjustment signal of the power-assisted motor control module to control the rotation speed of the power-assisted motor. These signals can be used to adjust the speed of the rear wheel power-assisted motor through the current to realize intelligent power-assisted control. For reference Figure 5 :Photoelectric code scanning circuit scheme diagram. The figure shows the code scanning circle angle is 16°, corresponding to the second gear, and the pulse sequence is 11100.

[0036] The mechanism and power are configured according to the principle of keeping the advantages of traditional bicycles, being simple, light and power-assisted. The main parameters of this embodiment are:

[0037] Power supply: lithium battery pack, 24vdc / 25Ah;

[0038] Motor: outer rotor brushless motor 250w / 24vdc;

[0039] Speed: 16km / h; (0~4, 4~8, 8~12, 12~16km / h four gears)

[0040] In summary, this specific embodiment provides a photoelectric torque sensor power-assisted motor control system based on a bicycle pedal servo, with a power-assisted ratio of up to 75% to 90%, realizing intelligent power-assisted control, and having the advantages of simplicity, high reliability, fast response speed, and low price. It is suitable for various types of power-assisted bicycles, and it will provide riders with a more comfortable and convenient riding experience.

Claims

1. A photoelectric torque sensor power-assisted motor control system is installed at the bicycle pedal, with pedal handles fixed at both ends of the pedal shaft, a jacket sleeved on the pedal shaft, a power-assisted motor installed on the rear wheel of the bicycle, and the power-assisted motor is communicatively connected to the motor control unit and the battery pack, characterized in that: An inner sleeve is also provided between the pedal shaft and the outer sleeve, and bearings are provided between the pedal shaft and the inner sleeve and between the outer sleeve and the inner sleeve. A sprocket is fixed at the end of the inner sleeve, and a hole is provided in the middle of the sprocket for the pedal shaft to pass through; the torque spring is sleeved and fixed on the pedal shaft, and a hanging strip for hooking the torque spring hook is provided on the inner side of the inner sleeve; the photoelectric code scanning device is provided on one side of the outer sleeve, including a sensor base and a sensor cover, the sensor base and the sensor cover form a circular cavity, the inner optical disc and the outer pulse disc, and the signal board for sending and receiving photoelectric signals are located in the circular cavity, the sensor base is installed at one end of the outer sleeve, and the middle of the inner optical disc is provided. The hole is press-fitted on the outer side of the inner sleeve; the hole in the outer pulse disk is press-fitted on the pedal shaft, the inner stop optical disk and the outer pulse disk rotate with the inner sleeve and the pedal shaft respectively, and both the inner stop optical disk and the outer pulse disk have vertical 90° protruding spoke edges around the belly of the disk, the belly of the inner stop optical disk and the outer pulse disk overlap, the spokes overlap, the spokes have the same width, and can slide relatively, when the pedal force is applied, under the action of the torque spring, the inner stop optical disk and the outer pulse disk rotate with the inner sleeve and the pedal shaft respectively to form a relative displacement angle, and the signal board for sending and receiving photoelectric signals is used to detect the relative displacement angle and send the detected signal to the motor control unit of the power-assisted motor.

2. The photoelectric torque sensor power-assisted motor control system according to claim 1, characterized in that: The outer sleeve is welded on the frame, an inner sleeve is installed through a pair of bearings at two ends of the inner side of the outer sleeve, and a pedal shaft is installed through a pair of bearings at two ends of the inner side of the inner sleeve.

3. The photoelectric torque sensor power-assisted motor control system according to claim 1, characterized in that: There is a semicircular ring in the middle of the torque spring, which is fixed to the pedal shaft with screws. The left and right parts of the torque spring have the same number of turns and opposite rotation directions. Hooks are symmetrically arranged at both ends of the torque spring, and the hooks are hung on the hanging strips on the inner wall of the inner sleeve. When the pedal shaft rotates, the inner sleeve rotates at the same time, and under the action of the torque spring, the two produce a relative displacement angle.

4. The photoelectric torque sensor power-assisted motor control system according to claim 1, characterized in that: The signal board for sending and receiving photoelectric signals is installed on the bottom plate in the cavity formed by the sensor cover and the base; the signal board is provided with two rows of photoelectric tube mounting holes, one on top and four on the bottom, and the hole spacing has four equal circumferential angles corresponding to the center of the pedal shaft; an arc-shaped groove is opened in the middle of the hole so that the above-mentioned two disc spokes can pass through the groove and divide the five holes into five pairs; a light-emitting diode for emitting light is installed on one side, and a photosensitive transistor for receiving light is installed on the other side.

5. The photoelectric torque sensor power-assisted motor control system according to claim 1, characterized in that: A long arc-shaped waist groove is arranged on the spoke edge of the inner optical disc, and five lamp holes with equal angles in two rows are arranged on the spoke edge of the outer pulse disc, one on top and four on the bottom, and the angle is the same as that of the lamp holes of the signal plate.

Images