Torque sensor, power assist device, power assist bicycle, and torque detection method

Abstract

The present invention is applicable to the power-assisting field, and provides a torque sensor, a power-assisting device, a power-assisting bicycle, and a torque detection method. The torque sensor includes: a central shaft, on which a first transmission member is fixed; a second transmission member, which is sleeved on the central shaft and can rotate relative to the central shaft, and the second transmission member is spaced apart from the first transmission member; a third transmission member, which is sleeved on the outside of the first transmission member and the second transmission member and simultaneously engages with the same side of the first transmission member and the second transmission member for transmission; a bearing seat, which is sleeved on the outside of the third transmission member, and the third transmission member can rotate relative to the bearing seat, and a strain gauge, which is provided on the outer wall of the bearing seat, and is used to detect the voltage change value of the bearing seat on the third transmission member. Through the torque transmission structure design, the dynamic torque on the central shaft in the existing structure is converted into a stable bending moment for measurement. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the field of bicycles, and in particular relates to a torque sensor, a power-assisting device, a power-assisted bicycle and a torque detection method. Background Art

[0002] A power-assisted bicycle is a new type of two-wheeled vehicle, a type of bicycle. It uses batteries as an auxiliary power source, is equipped with an electric motor, and has a power-assist system. It is a new type of transportation tool that can realize the integration of human riding and motor assistance. In the field of power-assisted bicycles, there are two main types of motor installation positions. One is the mid-mounted motor, which is installed in the middle position of the vehicle body, that is, the motor at the five-way position. This is called a mid-mounted motor. The mid-mounted motor is connected to the frame and is connected to the rear wheel through a chain to transmit power. At the same time, pedals are installed on both sides of the motor. When the motor has no power supply, the rider can achieve human riding by pedaling, and the resistance is no different from that of a normal bicycle. The other type is installed in the hub of the bicycle, which is called a hub motor.

[0003] The torque sensor of a mid-mounted power-assisted bicycle is the core technology of the bicycle. It is the detection end that collects riding torque during riding. The current mid-mounted power-assisted bicycle detects riding torque. The general method is to collect torque strain (the change in strain gauge resistance caused by torque strain) by attaching a strain gauge on the rotating deformation shaft (rotating central shaft / deformed body on the central shaft). The voltage signal of the strain gauge after deformation is collected through a half-bridge / full-bridge. After amplification and A / D processing, the signal is transmitted to a stationary signal receiving end via wireless communication to collect dynamic torque. At the same time, the power supply of the strain gauge on the rotating shaft is powered by electromagnetic induction (in the form of a primary and secondary coil transformer). This method requires dealing with wireless power supply and wireless communication issues, which makes signal processing complicated and poses the risk of external electromagnetic signal interference, requiring electromagnetic shielding. Summary of the Invention

[0004] The torque sensor provided in the embodiment of the present invention is intended to solve the problem in the prior art of needing to deal with wireless power supply and wireless communication, which leads to complicated signal processing, the risk of external electromagnetic signal interference, and the need for electromagnetic shielding.

[0005] The embodiment of the present invention is implemented as follows: a torque sensor for a mid-mounted motor of a power-assisted bicycle, comprising:

[0006] A middle shaft, used for connecting to the pedals, on which a first transmission member is fixed;

[0007] a second transmission member, sleeved on the central shaft and rotatable relative to the central shaft, the second transmission member being spaced apart from the first transmission member, and being used to connect a load;

[0008] a third transmission member, sleeved on the outside of the first transmission member and the second transmission member and meshing with the same side of the first transmission member and the second transmission member for transmission;

[0009] A bearing seat is sleeved outside the third transmission member, the third transmission member can rotate relative to the bearing seat, and one end of the bearing seat is used for fixing the vehicle body;

[0010] A strain gauge is provided on the outer wall of the bearing seat, and is used to detect a voltage change value generated by the bearing seat when the third transmission member transmits power to the first transmission member and the second transmission member.

[0011] Furthermore, the first transmission member is integrally formed on the central shaft.

[0012] Furthermore, the bearing seat includes a load-bearing part sleeved outside the third transmission member, a load-bearing part fixed to the vehicle body, and a transition part connecting the load-bearing part and the load-bearing part. The inner diameter of the load-bearing part is smaller than the load-bearing part, and the strain gauge is arranged on the load-bearing part.

[0013] Furthermore, the transition portion is a conical structure.

[0014] The present invention also provides a power assist device, including the aforementioned torque sensor and a fourth transmission member, wherein the fourth transmission member is rotatably mounted outside the central shaft and is fixedly connected to the second transmission member, and the second transmission member can drive the fourth transmission member to rotate in one direction, and the fourth transmission member is used to connect a load.

[0015] Furthermore, one end of the second transmission member away from the first transmission member extends out of the bearing seat to form a fixed portion, the fixed portion is sleeved with a first one-way linkage member, and the fourth transmission member is sleeved on the first one-way linkage member.

[0016] The present invention also provides a power-assisted bicycle, comprising:

[0017] body;

[0018] a central motor, disposed on the vehicle body, wherein an output end of the central motor is provided with a fifth transmission member; and

[0019] In the aforementioned power-assisting device, the fifth transmission member is engaged with the fourth transmission member for transmission and can drive the fourth transmission member to rotate in one direction.

[0020] Furthermore, the driving end of the central motor is provided with a second one-way linkage, the fifth transmission member is connected to the second one-way linkage, and the central motor can drive the fifth transmission member to rotate the fourth transmission member through the second one-way linkage.

[0021] The present invention also provides a torque detection method, comprising the following steps:

[0022] Get the bending moment of the bearing seat;

[0023] Obtaining a radial force of the bearing seat according to the bending moment of the bearing seat and the force arm of the bearing seat, wherein the radial force of the bearing seat is equal to the radial force of the third transmission member;

[0024] Obtaining the circumferential force of the first transmission member and the circumferential force of the second transmission member according to the radial force of the bearing seat, the pressure angle of the first transmission member, and the pressure angle of the second transmission member;

[0025] The torque of the central shaft is obtained according to the circumferential force and radius of the first transmission member and the circumferential force and radius of the second transmission member.

[0026] Furthermore, the step of obtaining the bending moment of the bearing seat specifically includes:

[0027] The strain force of the bearing seat is obtained, and the bending moment of the bearing seat is obtained according to the strain force.

[0028] The beneficial effects achieved by the present invention are as follows: by arranging the first transmission member and the second transmission member at intervals on the central shaft, and cooperating with the third transmission member for transmission outside the first and second transmission members, during the rotation of the central shaft input torque, the first transmission member can drive the second transmission member to rotate through the third transmission member, and the second transmission member is used to link with the wheel, so that the pedal input torque can drive the wheel to rotate. At the same time, since one end of the bearing seat is fixed on the vehicle body, a cantilever beam structure is formed, and a radial force is applied to the bearing seat at the other end through the first transmission member and the second transmission member, so that the radial force of the bearing seat can be measured by detecting the bending moment on the bearing seat through the strain gauge, so that the magnitude of the central shaft torque, that is, the magnitude of the central shaft input force, can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of a power assist device provided by the present invention;

[0030] Figure 2 yes Figure 1 Cross-section at AA;

[0031] Figure 3 yes Figure 1 Cross-section at the middle BB;

[0032] Figure 4 yes Figure 1 Cross-section at BB. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The embodiment of the present invention arranges the first transmission member and the second transmission member at intervals on the central shaft, and cooperates with the third transmission member for transmission outside the first and second transmission members. During the rotation of the central shaft input torque, the first transmission member can drive the second transmission member to rotate through the third transmission member, and the second transmission member is used to link with the wheel, so that the pedal input torque can drive the wheel to rotate. At the same time, since one end of the bearing seat is fixed on the vehicle body, a cantilever beam structure is formed, and a radial force is applied to the bearing seat at the other end through the first transmission member and the second transmission member, so that the radial force of the bearing seat can be measured by detecting the bending moment on the bearing seat through the strain gauge, so that the magnitude of the central shaft torque, that is, the magnitude of the central shaft input force, can be obtained.

[0035] Example 1

[0036] See also Figure 1-2 The embodiment of the present invention provides a torque sensor for a mid-mounted motor of a power-assisted bicycle, comprising a central axis 1, a first transmission member 2, a second transmission member 3, a third transmission member 4, a bearing seat 5, and a strain gauge 7. The central axis 1 is used to connect to the pedals to rotate the central axis 1, the first transmission member 2 is fixed to the central axis 1, the second transmission member 3 is sleeved on the central axis 1 and can rotate relative to the central axis 1, the second transmission member 3 is spaced apart from the first transmission member 2, the second transmission member 3 is used to connect to the load, that is, the second transmission member 3 is used to link with the wheel so that it can drive the wheel to rotate when the central axis 1 rotates, the third transmission member 4 is sleeved on the outside of the first transmission member 2 and the second transmission member 3 and simultaneously engages with the same side of the first transmission member 2 and the second transmission member 3, that is, the first transmission member 2 and the second transmission member 3 are engaged with the third transmission member 4. Part 4 is eccentrically arranged, that is, when the first transmission member 2 rotates, the second transmission member 3 can only be driven to rotate by the third transmission member 4, while at the same time it can ensure that the radial forces of the first transmission member 2 and the second transmission member 3 can be synchronously transmitted to the third transmission member 4, the bearing seat 5 is sleeved outside the third transmission member 4, the third transmission member 4 can rotate relative to the bearing seat 5, one end of the bearing seat 5 is used to be fixed to the vehicle body, the strain gauge 7 is arranged on the outer wall of the bearing seat 5, the strain gauge 7 is used to detect the voltage change value generated by the bearing seat 5 when the third transmission member 4 transmits to the first transmission member 2 and the second transmission member 3.

[0037] The first transmission member 2 and the second transmission member 3 are arranged at intervals on the central axis 1, and the third transmission member 4 is cooperated with the first transmission member 2 and the second transmission member 3 for transmission at the same time. During the rotation of the central axis 1 due to input torque, the first transmission member 2 can drive the second transmission member 3 to rotate through the third transmission member 4, and the second transmission member 3 is used to link with the wheel, so that the pedal input torque can drive the wheel to rotate. At the same time, since one end of the bearing seat 5 is fixed on the vehicle body, a cantilever beam structure is formed, and a radial force is applied to the bearing seat 5 through the first transmission member 2 and the second transmission member 3 at the other end, so that the radial force of the bearing seat 5 can be measured by detecting the bending moment on the bearing seat 5 through the strain gauge 7, so that the magnitude of the torque of the central axis 1, that is, the magnitude of the input force of the central axis 1, can be obtained.

[0038] The torque sensor provided by the present invention converts the dynamic torque on the central axis 1 in the existing structure into a stable bending moment for measurement through the torque transmission structure design. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0039] Specifically, the third transmission member 4 and the bearing seat 5, and the middle shaft 1 and the second transmission member 3 can be connected by bearings 6.

[0040] Furthermore, the first transmission member 2 is integrally formed on the central shaft 1 , which can improve the compactness and reliability of the first transmission member 2 and the central peripheral structure.

[0041] In this embodiment, the first transmission member 2 and the second transmission member 3 are both external gears, and the third transmission member 4 is an internal gear.

[0042] Example 2

[0043] See also Figure 2 On the basis of embodiment 1, further, the bearing seat 5 includes a load-bearing part 51 sleeved on the third transmission member 4 (that is, the load-bearing part 51 is sleeved on the bearing 6 outside the third transmission member 4), a load-bearing part 52 fixed to the vehicle body, and a transition part 53 connecting the load-bearing part 52 and the load-bearing part 51. The inner diameter of the load-bearing part 52 is smaller than that of the load-bearing part 51, and the strain gauge 7 is provided on the load-bearing part 52. In this way, on the one hand, the space occupied by the bearing seat 5 can be reduced, and on the other hand, when the load-bearing part 51 is subjected to radial force, the degree of deformation of the load-bearing part 52 can be increased, so that the strain gauge 7 can obtain a more obvious numerical change, thereby improving the accuracy of obtaining the bending moment of the bearing seat 5.

[0044] Specifically, a flange 521 may be provided on the force-bearing portion 52 , so as to facilitate the connection and fixation between the bearing seat 5 and the vehicle body.

[0045] Furthermore, the transition portion 53 is a conical structure, that is, the outer wall of the transition portion 53 is an arc surface structure, which can avoid the transition portion 53 being concave, so that when the load-bearing portion 51 is applied with a radial force, the force is attenuated when it is transmitted to the load-bearing portion 52, and can also avoid the transition portion 53 being convex, so that when the load-bearing portion 51 is applied with a radial force, the load-bearing portion 52 is difficult to deform, thereby affecting the problem that the value change of the strain gauge 7 is not obvious.

[0046] In addition, it can be understood that the transition portion 63 can also be a basic deformation of the conical structure, such as a vertical right-angle structure or a structure with other angles.

[0047] Example 3

[0048] See also Figure 2 The present invention also provides a power assist device, including the aforementioned torque sensor and a fourth transmission member 8. The fourth transmission member 8 is rotatably mounted outside the central shaft 1 and is fixedly connected to the second transmission member 3. The second transmission member 3 can drive the fourth transmission member 8 to rotate in one direction. The fourth transmission member 8 is used to connect a load, which is a wheel.

[0049] In this way, the third transmission member 4 unidirectionally drives the fourth transmission member 8 to rotate. When the user pedals, the torque applied to the central axle 1 is transmitted by the third transmission member 4 to the second transmission member 3, and then by the second transmission member 3 to the fourth transmission member 8 unidirectionally, thereby driving the load, i.e., the wheel, to rotate. However, when the wheel is assisted, the fourth transmission member 8 does not drive the third transmission member 4 to rotate, and thus does not transfer the load to the central axle 1.

[0050] The power assist device provided by the present invention converts the dynamic torque on the central axis 1 in the existing structure into a stable bending moment for measurement through the torque transmission structure design. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0051] Furthermore, the fourth transmission member 8 is provided with a load connecting member 20 for connecting a load.

[0052] In this embodiment, the load connection member 20 may be a crankset.

[0053] Example 4

[0054] See also Figure 2On the basis of the third embodiment, the second transmission member 3 further extends from the bearing seat 5 at one end away from the first transmission member 2 to form a fixed portion 31. The first one-way linkage member 30 is sleeved on the fixed portion 31, and the fourth transmission member 8 is sleeved outside the first one-way linkage member 30. In this way, the second transmission member 3 and the fourth transmission member 8 are fixed in a nested manner via the fixed portion 31, which facilitates the rotatable fixation of the fourth transmission member 8 with the second transmission member 2. Even if the fourth transmission member 8 can rotate relative to the second transmission member 3 on the second transmission member 3, the connection is more stable and reliable. The provision of the first one-way linkage member 30 ensures that the second transmission member 3 can drive the fourth transmission member 8 to rotate, without causing the fourth transmission member 8 to drive the second transmission member 3 to rotate.

[0055] In this embodiment, the first one-way transmission member 30 may be a one-way bearing.

[0056] Example 5

[0057] The present invention provides a power-assisted bicycle comprising a bicycle body (not shown), a mid-mounted motor (not shown), and the aforementioned power-assisting device. The mid-mounted motor is mounted on the bicycle body, and a fifth transmission member 10 is provided at the output end of the mid-mounted motor. The fifth transmission member 10 engages with a fourth transmission member 8 and can drive the fourth transmission member 8 to rotate in one direction.

[0058] In this way, when the torque is input to the middle shaft 1, the fourth transmission member 8 will not drive the fifth transmission member 10 to rotate, and will not drive the output end of the middle motor to rotate, so as to avoid increasing the load on the human end due to dragging the motor. When the middle motor rotates, it can drive the fifth transmission member 10 to drive the fourth transmission member 8 to operate, thereby driving the load connecting member 20, thereby reducing the load on the input end of the middle shaft 1 and producing a power assist effect.

[0059] The power-assisted bicycle provided by the present invention converts the dynamic torque on the central axis 1 in the existing structure into a stable bending moment for measurement through the torque transmission structure design. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0060] Furthermore, a second one-way linkage 9 is provided at the driving end of the central motor, and a fifth transmission member 10 is sleeved and connected to the second one-way linkage 9. Specifically, the second one-way linkage 9 can be a one-way bearing, and the fifth transmission member 10 is sleeved outside the second one-way linkage 9. The central motor can drive the fifth transmission member 10 through the second one-way linkage 9 to drive the fourth transmission member 8 to rotate. The second one-way linkage 9 enables the central motor to achieve one-way transmission of the fourth transmission member 8, thereby achieving one-way assistance of the central motor.

[0061] Example 6

[0062] See also Figure 2-4 The present invention also provides a torque detection method, comprising the following steps:

[0063] S1: Obtain the bending moment Mr of the bearing seat 5. Specifically, obtain the strain force of the bearing seat 5, and obtain the bending moment Mr of the bearing seat 5 according to the strain force;

[0064] According to the universal measurement method of the strain gauge 7 , the bending moment Mr exerted on the bearing seat 5 can be measured and calibrated by the strain gauge 7 on the bearing seat 5 .

[0065] S2: Obtain the radial force of the bearing seat 5 according to the bending moment of the bearing seat 5 and the force arm L of the bearing seat 5, wherein the radial force of the bearing seat 5 is equal to the radial force of the third transmission member 4;

[0066] The bending moment of the bearing seat 5 is generated by the radial force Fr of the third transmission member 4, and the force arm L of the bearing seat 5 is the distance from the force center of the third transmission member 4 to the connection between the bearing seat 5 and the vehicle body. Therefore, the calculation formula is: Mr = Fr*L.

[0067] S3: Obtain the circumferential force Ft1 of the first transmission member 2 and the circumferential force Ft2 of the second transmission member 3 according to the radial force Fr of the bearing seat 5, the pressure angle α of the first transmission member 2, and the pressure angle α of the second transmission member 3;

[0068] The radial force Fr of the bearing seat 5 and the radial force Fr' of the third transmission member 4 are of the same magnitude but opposite in direction. The radial force of the third transmission member 4 is the sum of the radial force Fr1 of the first transmission member 2 and the radial force Fr2 of the second transmission member 3. Therefore, the calculation formula is Fr = Fr1 + Fr2.

[0069] And because: Ft1=Fr1 / tanα

[0070] Ft2=Fr2 / tanα

[0071] We can get: Ft1+Ft2=Fr / tanα

[0072] The pressure angle α is a fixed value of the mechanical parameter of the transmission member, and the pressure angles of the first transmission member 2, the second transmission member 3, and the third transmission member 4 that cooperate with each other are the same, which is α;

[0073] S4: Obtain the torsion of the central shaft 1 according to the circumferential force and radius of the first transmission member 2 and the circumferential force and radius of the second transmission member 3 .

[0074] According to the force analysis of the middle shaft 1, the torques of the first gear and the second gear are both the torque M of the middle shaft 1, so:

[0075] M=Ft1*R1

[0076] M=Ft2*R2

[0077] Then we have: M / R1+M / R2=Fr / tanα

[0078] Thus we can obtain: M=Fr*R1*R2 / [(R1+R2)*tanα]=Mr*R1*R2 / [(R1+R2)*tanα*L].

[0079] Example 7

[0080] On the basis of the sixth embodiment, the step of obtaining the bending moment of the bearing seat 5 specifically includes:

[0081] S11: Obtain the strain force of the bearing seat 5, and obtain the bending moment of the bearing seat 5 according to the strain force.

[0082] The resistance change of the bearing seat 5 when subjected to force is detected by the strain gauge 7 provided on the bearing seat 5, thereby obtaining the generated bending moment Mr.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A torque sensor for a mid-mounted motor of a power-assisted bicycle, characterized in that: include: A middle shaft, used for connecting to the pedals, on which a first transmission member is fixed; a second transmission member, sleeved on the central shaft and rotatable relative to the central shaft, the second transmission member being spaced apart from the first transmission member, and being used to connect a load; a third transmission member, sleeved on the outside of the first transmission member and the second transmission member and meshing with the same side of the first transmission member and the second transmission member for transmission; A bearing seat is sleeved outside the third transmission member, the third transmission member can rotate relative to the bearing seat, and one end of the bearing seat is used for fixing the vehicle body; a strain gauge, provided on an outer wall of the bearing seat, for detecting a voltage change value generated by the bearing seat when the third transmission member transmits power to the first transmission member and the second transmission member; The bearing seat includes a load-bearing part sleeved outside the third transmission member, a load-bearing part fixed to the vehicle body, and a transition part connecting the load-bearing part and the load-bearing part. The inner diameter of the load-bearing part is smaller than the load-bearing part, and the strain gauge is arranged on the load-bearing part.

2. The torque sensor according to claim 1, wherein: The first transmission member is integrally formed on the central shaft.

3. The torque sensor according to claim 1, wherein: The transition portion is a conical structure.

4. A power assist device, characterized in that: It includes the torque sensor as described in any one of claims 1 to 3 and a fourth transmission member, the fourth transmission member is rotatably mounted outside the central shaft and is fixedly connected to the second transmission member, the second transmission member can drive the fourth transmission member to rotate in one direction, and the fourth transmission member is used to connect a load.

5. The power assist device according to claim 4, characterized in that: One end of the second transmission member away from the first transmission member extends out of the bearing seat to form a fixed portion, the fixed portion is sleeved with a first one-way linkage member, and the fourth transmission member is sleeved on the first one-way linkage member.

6. A power-assisted bicycle, characterized in that: include: body; A central motor is provided on the vehicle body, and a fifth transmission member is provided at the output end of the central motor; as well as According to the power assist device as described in claim 4 or 5, the fifth transmission member is engaged with the fourth transmission member for transmission and can drive the fourth transmission member to rotate in one direction.

7. The power-assisted bicycle according to claim 6, wherein: The driving end of the central motor is provided with a second one-way linkage, and the fifth transmission member is connected to the second one-way linkage. The central motor can drive the fifth transmission member to rotate by the second one-way linkage.

8. A torque detection method, used for the torque sensor according to any one of claims 1 to 3, characterized in that: The following steps are involved: Get the bending moment of the bearing seat; Obtaining a radial force of the bearing seat according to the bending moment of the bearing seat and the force arm of the bearing seat, wherein the radial force of the bearing seat is equal to the radial force of the third transmission member; Obtaining the circumferential force of the first transmission member and the circumferential force of the second transmission member according to the radial force of the bearing seat, the pressure angle of the first transmission member, and the pressure angle of the second transmission member; The torque of the central shaft is obtained according to the circumferential force and radius of the first transmission member and the circumferential force and radius of the second transmission member.

9. The torque detection method according to claim 8, wherein: The step of obtaining the bending moment of the bearing seat specifically includes: The strain force of the bearing seat is obtained, and the bending moment of the bearing seat is obtained according to the strain force.

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