Electric bicycle hub motor with built-in power assist sensor

Abstract

The present invention relates to an electric bicycle hub motor with a built-in power-assisting sensor, comprising a main shaft, characterized in that: a stepped platform is provided on the main shaft, a bearing sleeve is mounted on the main shaft, the bearing sleeve is provided with a square inner hole matching the shape of the stepped platform, the outer side of the bearing sleeve is supported on the end cover through an end cover support bearing, the inner side of the bearing sleeve is supported on the stepped platform, an elastic body support groove is provided on the vertical side of the stepped platform, an elastic body is overlapped on the elastic body support groove to form a simply supported beam structure, a strain gauge is fixedly connected to the inner side of the elastic body, a force transmission gasket is inserted into the groove on the side wall of the square inner hole of the bearing sleeve, and the simply supported beam structure of the elastic body mounted on the bearing sleeve, the strain gauge and the force transmission gasket together form a simply supported beam force measurement mechanism. Beneficial effect: The elastomer of the present invention does not participate in the hub support, the reliability of the elastomer is significantly improved, and the elastomer is fixed and does not rotate relative to the motor shaft, and no wireless transmission module and receiving module of the torque signal are required, which not only saves space but also saves costs.

Description

Technical Field

[0001] The invention belongs to the field of motors, and in particular relates to an electric bicycle hub motor with a built-in power-assisting sensor. Background Art

[0002] At present, there are two ways to control the power of electric bicycles. One is to measure the pedaling speed of the rider through a speed sensor and roughly estimate the power of the power according to the speed. The other is to measure the pedaling force of the rider through a torque sensor and accurately calculate the power of the power according to the size of the pedaling force. In the above two power-assisting methods, the power-assisting sensor is installed at the middle shaft of the five-way, and the speed signal of the middle shaft or the torque signal of the middle shaft is transmitted to the motor controller to control the output power of the motor, thereby achieving power assistance. The two power-assisting methods have their own advantages and disadvantages. The advantages of the speed-type power-assisting method are simple structure, strong impact resistance, low cost, and convenient installation, and the disadvantage is poor power-assisting effect; the advantages of the torque-type power-assisting method are good power-assisting effect, and the disadvantages are complex structure, weak impact resistance, high cost, and troublesome installation. Although the torque sensor has many disadvantages, it has excellent performance in power-assisting effect, and mid-to-high-end electric bicycles generally use torque sensors. In order to reduce the trouble of installing the torque sensor, some companies have launched hub motors with built-in torque sensors, such as the patent document publication number CN107054542A discloses a "hub motor with torque sensing function and an electric bicycle using the motor". In the above structure, one end of the elastomer is fixedly connected to the flywheel, and the other end is fixedly connected to the motor hub. The elastomer acts as a hub support. The impact of the hub during riding is directly loaded on the elastomer, and the elastomer cannot be made too thick. If it is made stronger, the deformation will be too small and cannot meet the strain output requirements, so the reliability is poor. In addition, the elastomer rotates with the hub, so a torque signal wireless transmission module and receiving module are also required, which are large in size, complex in structure, high in cost, and poor in comprehensive performance. A power-assisting sensor that can be built into the hub motor, has a good power-assisting effect, is small in size, simple in structure, low in cost, and high in reliability is a product that the industry is looking forward to. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned technology and provide an electric bicycle hub motor with a built-in power-assisting sensor. The mechanical support structure is used to convert the torque detection into pressure detection. The elastomer does not participate in the hub support, and the reliability of the measurement force is significantly improved.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an electric bicycle hub motor with a built-in power-assisting sensor, comprising an end cover, a housing, a stator and a main shaft, characterized in that: a stepped platform is provided on the main shaft, the cross-sectional shape of the stepped platform is square, a bearing sleeve is mounted on the main shaft, the bearing sleeve is provided with a square inner hole matching the shape of the stepped platform, the outer side of the bearing sleeve is supported on the end cover through the end cover support bearing, and the inner side of the bearing sleeve is supported on the stepped platform, an elastic body support groove is provided on the vertical side of the stepped platform, an elastic body is overlapped on the elastic body support groove to form a simply supported beam structure, a strain gauge is fixedly connected to the inner side of the elastomer, a force transmission gasket is inserted in the groove on the side wall of the square inner hole of the bearing sleeve, and the simply supported beam structure of the bearing sleeve mounted elastic body, the strain gauge and the force transmission gasket together constitute a simply supported beam force measurement mechanism.

[0005] The inner side of the bearing sleeve is supported on a plurality of bearing sleeve vertical support needles on the upper and lower surfaces of the stepped platform.

[0006] A radial recessed platform is arranged on the inner end surface of the bearing sleeve, and a radial thrust roller of the bearing sleeve is arranged on the radial recessed platform.

[0007] A buffer gap is provided between the inner diameter of the bearing sleeve and the main shaft, and the buffer gap is 0.05-0.15 mm.

[0008] An elastomeric fixing ring is keyed onto the main shaft and placed at the inner end of the stepped platform. An elastomer is provided on the elastomeric fixing ring to form a cantilever beam structure. A strain gauge is fixedly connected to the inner side of the elastomer. A bearing sleeve inner side protrusion is provided on the side wall of the square inner hole of the bearing sleeve. The cantilever beam structure of the elastomer mounted on the bearing sleeve, the strain gauge and the bearing sleeve inner side protrusion together form a cantilever beam force measuring mechanism.

[0009] Beneficial effects: The present invention measures the change of the rider's pedaling force with an extremely simple structure. At the same time, the elastomer does not participate in the hub support, and the reliability is significantly improved. Moreover, the elastomer is fixed relative to the motor main shaft and does not rotate, and there is no need for a torque signal wireless sending module and receiving module, which not only saves space but also saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a partial cross-sectional view of the present invention;

[0011] Figure 2 is an AA transverse cross-sectional view of Embodiment 1 of the present invention;

[0012] Figure 3 is a longitudinal cross-sectional view taken along line BB of Embodiment 1 of the present invention;

[0013] Figure 4 is a longitudinal sectional perspective view of embodiment 1 of the present invention;

[0014] Figure 5is a three-dimensional exploded view of embodiment 1 of the present invention;

[0015] Figure 6 is a schematic diagram of a bearing sleeve and a needle roller according to Embodiment 1 of the present invention;

[0016] Figure 7 is an AA transverse cross-sectional view of Embodiment 2 of the present invention;

[0017] Figure 8 is a longitudinal cross-sectional view taken along line BB of Embodiment 2 of the present invention;

[0018] Fig. 9 is a longitudinal sectional perspective view of embodiment 2 of the present invention;

[0019] Fig.10 is a three-dimensional exploded view of embodiment 2 of the present invention;

[0020] Fig.11 is a schematic diagram of a bearing sleeve and a needle roller according to Embodiment 2 of the present invention;

[0021] Fig.12 is a schematic diagram of an elastic body according to Example 2 of the present invention;

[0022] Fig.13 is a longitudinal sectional view of embodiment 3 of the present invention;

[0023] Fig.14 is a longitudinal sectional view of embodiment 4 of the present invention;

[0024] Fig.15 It is a force diagram of the hub motor of the present invention.

[0025] In the figure: 1. main shaft, 1-1. needle roller contact surface, 1-2. elastomer support platform, 2. bearing sleeve vertical direction support needle roller, 2-1. bearing sleeve radial thrust needle roller, 3. bearing sleeve, 3-1. inner groove of bearing sleeve, 3-2. inner protrusion of bearing sleeve, 4. end cover support bearing, 5. end cover, 6. housing, 7. elastomer, 7-1. elastomer fixing ring, 8. force transmission gasket, 9. stator, 10. power assist signal output board, 11. flywheel, 12. strain gauge, 13. magnet, 14. Hall, 15. pedal, 16. chain, 301. buffer gap between bearing sleeve and main shaft. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention is described in detail below in conjunction with preferred embodiments.

[0027] Example 1

[0028] See attached for details Figure 1-7The present embodiment provides an electric bicycle hub motor with a built-in power-assisting sensor, including an end cover 5, a housing 6, a stator 9, a torque signal output board 10, a flywheel 11 and a main shaft 1, wherein the main shaft is provided with a stepped platform, the cross-sectional shape of the stepped platform is square, a bearing sleeve 3 is mounted on the main shaft, the bearing sleeve is provided with a square inner hole matching the shape of the stepped platform, the outer side of the bearing sleeve is supported on the end cover through an end cover support bearing 4, the inner side of the bearing sleeve is supported on the needle roller contact surface 1-1 of the stepped platform, and a plurality of bearing sleeves are arranged on the upper surface of the upper and lower needle roller contact surfaces of the stepped platform to support needle rollers 2 in a vertical direction. The vertical side of the step platform is provided with an elastic body support groove to form an elastic body support platform 1-2, and the elastic body 7 is overlapped on the elastic body support platform. The elastic body support platform and the elastic body form a simply supported beam structure. A strain gauge 12 is fixedly connected to the inner side of the elastic body. A force transmission gasket 8 is inserted into the inner groove 3-1 of the bearing sleeve on the side wall of the square inner hole of the bearing sleeve. The elastic body simply supported beam structure, strain gauge and force transmission gasket of the bearing sleeve together constitute a simply supported beam force measurement mechanism. A radial concave platform is provided on the inner end surface of the bearing sleeve, and a radial thrust roller 2-1 of the bearing sleeve is placed on the radial concave platform.

[0029] Example 2

[0030] This embodiment provides an electric bicycle hub motor with a built-in power assist sensor, comprising an end cover 5, a housing 6, a stator 9, a torque signal output board 10, a flywheel 11 and a main shaft 1, wherein the main shaft is provided with a stepped platform, the cross-sectional shape of the stepped platform is square, the main shaft is provided with a bearing sleeve, the bearing sleeve is provided with a square inner hole matching the shape of the stepped platform, the outer side of the bearing sleeve is supported on the end cover through the end cover support bearing, the inner side of the bearing sleeve is supported on the needle roller contact surface 1-1 of the stepped platform, and a plurality of bearing sleeve vertical direction support needle rollers 2 are arranged on the upper surface of the upper and lower needle roller contact surfaces of the stepped platform. An elastic body fixing ring 7-1 is keyed to the main shaft, the elastic body fixing ring is placed at the inner side end of the stepped platform, an elastic body is provided on the elastic body fixing ring to form a cantilever beam structure, a strain gauge is fixed to the inner side of the elastic body, and a bearing sleeve inner side protrusion 3-2 is provided on the side wall of the square inner hole of the bearing sleeve, and the cantilever beam structure of the bearing sleeve sleeve elastic body, the strain gauge and the inner side protrusion of the bearing sleeve together constitute a cantilever beam force measurement mechanism.

[0031] like Figure 3 , 8 As shown in Figures 13 and 14, the preferred solution of this embodiment is that a buffer gap 301 is provided between the inner diameter of the bearing sleeve and the main shaft, and the buffer gap is 0.05-0.15 mm. There is a gap between the bearing sleeve and the main shaft, and the gap is smaller than the maximum deformable amount of the elastomer, so as to protect the elastomer and prevent the plastic deformation of the elastomer caused by overload.

[0032] Example 3

[0033] The magnet is fixed to the bearing sleeve and the Hall is fixed to the main shaft. When the bearing sleeve is pulled by the chain, the elastic body undergoes a slight deformation, the relative position between the magnet and the Hall changes, and the Hall output signal also changes accordingly.

[0034] Example 4

[0035] The magnet is fixed to the bearing sleeve, and the Hall is fixed to the elastic body fixing ring. When the bearing sleeve is subjected to chain tension, the elastic body undergoes a slight deformation, the relative position between the magnet and the Hall changes, and the Hall output signal also changes accordingly.

[0036] The difference between Example 1 and Example 2 or between Example 3 and Example 4 is the force form of the elastic body. The force form of the elastic body in Example 1 and Example 3 is a simply supported beam structure, and the force form of the elastic body in Example 2 and Example 4 is a cantilever beam structure. The difference between Examples 1 and 2 and Examples 3 and 4 is that the force detection element in Examples 1 and 2 is a strain gauge, and the force detection element in Examples 3 and 4 is a Hall.

[0037] Working process and principle

[0038] For electric bicycle power assistance, being able to accurately and timely understand the rider's riding intention is the key to achieving the best power assistance effect, that is, accurately measuring the real-time changes in the rider's pedaling force. Fig.15 As shown, the rider steps on the pedals, and the pedal force F1 is transmitted to the flywheel through the chain 16, and the chain tension F2 acts on the elastic body through the flywheel, the end cover, the end cover support bearing, the bearing sleeve, and the force transmission gasket. There is a proportional relationship between the rider's pedal force F1 and the chain tension F2 acting on the elastic body, and the change conditions are the same. Therefore, as long as the change conditions of the force on the elastic body are measured, the rider's riding intention can be understood. In the present invention, the elastic body, the strain gauge, and the power-assist signal output plate constitute the wheel hub built-in power-assist sensor.

[0039] like Figure 3 As shown, the specific working process of the power-assisting sensor is that the chain tension F2 acts on the center position of the simply supported beam elastic body, forcing the elastic body to undergo corresponding deformation. The strain gauge attached to the elastic body transmits the deformation degree of the elastic body to the power-assisting signal output board in the form of resistance change. The power-assisting signal output board will output an electrical signal that is proportional to the pedal force and has the same change situation. The motor controller outputs the corresponding power according to the above-mentioned power-assisting signal to achieve power assistance.

[0040] The existing hub motor with built-in torque sensor measures the physical quantity of the torque between the flywheel and the motor housing, that is, the total torque of the wheel hub driven by the rider. The present invention adds a bearing sleeve between the end cover support bearing and the main shaft. The bearing sleeve does not rotate relative to the main shaft. The present invention can detect the horizontal tension of the chain, thereby converting the torque detection into pressure detection. The elastomer does not rotate with the wheel hub, and no wireless transceiver is required. This not only simplifies the structure, but also avoids the disadvantage of the elastomer supporting the weight of the entire vehicle, thereby improving reliability.

[0041] The detailed description of the electric bicycle hub motor with a built-in power-assisting sensor in the above reference embodiment is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. An electric bicycle hub motor with a built-in power assist sensor, comprising an end cover, a housing, a stator and a main shaft, characterized in that: A step platform is provided on the main shaft, and the cross-section of the step platform is square. A bearing sleeve is mounted on the main shaft, and the bearing sleeve is provided with a square inner hole matching the shape of the step platform, and the bearing support is arranged between the outer side of the bearing sleeve and the end cover; the inner side of the bearing sleeve is supported on the step platform, and an elastic body support groove is provided on the vertical side of the step platform, and an elastomer is overlapped on the elastomer support groove to form a simply supported beam structure, and an inner groove of the bearing sleeve is provided on the side wall corresponding to the elastomer in the square inner hole of the bearing sleeve, and a force transmission gasket is inserted in the inner groove of the bearing sleeve, and a strain gauge is fixedly connected to the inner side of the elastomer; the bearing sleeve, the simply supported beam structure, the strain gauge and the force transmission gasket together constitute a simply supported beam force measuring mechanism.

2. The electric bicycle hub motor with built-in power assist sensor according to claim 1 is characterized in that: A row of a plurality of supporting needle rollers placed along the axial direction are respectively arranged on the upper and lower surfaces of the stepped platform, and the inner side of the bearing sleeve is supported on the supporting needle rollers.

3. The electric bicycle hub motor with built-in power assist sensor according to claim 1 or 2, characterized in that: A radial recessed platform is arranged on the inner end surface of the bearing sleeve, and a radial thrust roller of the bearing sleeve is arranged on the radial recessed platform.

4. The electric bicycle hub motor with built-in power assist sensor according to claim 3 is characterized in that: A buffer gap is provided between the inner diameter of the bearing sleeve and the main shaft, and the buffer gap is 0.05-0.15 mm.

5. The electric bicycle hub motor with built-in power assist sensor according to claim 1 is characterized in that: An elastomeric fixing ring is keyed onto the main shaft and placed at the inner end of the stepped platform. An elastomer is provided on the elastomeric fixing ring to form a cantilever beam structure. A strain gauge is fixedly connected to the inner side of the elastomer. A bearing sleeve inner side protrusion is provided on the side wall of the square inner hole of the bearing sleeve. The cantilever beam structure of the elastomer mounted on the bearing sleeve, the strain gauge and the bearing sleeve inner side protrusion together form a cantilever beam force measuring mechanism.

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