Power Unit Mounting Bracket Rigidity and Fastening
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Solution Overview
Problem
Conventional power-assisted bicycles face challenges in achieving high rigidity for the power unit mounting brackets without increasing manufacturing costs, as higher rigidity reduces the ability of plate-like portions to elastically deform and clamp the mounting portion effectively.
Innovation Solution
The power-assisted bicycle employs an arcuate-shaped power unit mounting bracket made of aluminum alloy, with a molded portion and side plates, allowing for high rigidity without the need for significant elastic deformation, and utilizing screw holes and through holes for secure fastening, which reduces the necessity for high manufacturing accuracy and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rigidity of the power unit mounting bracket is increased, then the fastening properties and stability are improved, but the ability of plate-like portions to elastically deform and clamp the mounting portion is reduced
Solution Approach 1:
The mounting bracket is divided into multiple plate-like portions that can independently elastically deform. Each plate-like portion acts as a separate clamping element, allowing the bracket to maintain overall rigidity while individual segments provide the necessary elastic deformation for effective clamping of the mounting portion.
2Strength
If the rigidity of the mounting bracket is increased, then the fastening properties are improved, but the manufacturing cost increases due to higher accuracy requirements
Solution Approach 1:
The bracket is designed with specific geometric parameters including arcuate shapes and strategically positioned through holes that alter the stiffness distribution. These parameter changes allow the bracket to achieve high rigidity in critical mounting areas while maintaining manufacturability through standard aluminum alloy materials and conventional manufacturing processes.
Solution Approach 2:
The mounting bracket incorporates arcuate-shaped plate-like portions with curved geometries. These curved structures provide inherent flexibility and elastic deformation capability while maintaining overall structural rigidity, eliminating the need for high manufacturing accuracy and reducing production costs.
3Adaptability or versatility
If the plate-like portions are designed for high elastic deformation, then the clamping capability is improved, but the rigidity of the mounting structure is reduced
Solution Approach 1:
The mounting bracket is segmented into multiple plate-like portions that can independently deform. This segmentation allows specific regions to provide elastic clamping action while other regions maintain structural rigidity, resolving the contradiction between clamping capability and overall structural strength.
Solution Approach 2:
Different regions of the mounting bracket are designed with different structural qualities. The plate-like portions have local flexibility for clamping, while the overall bracket structure and connection points to the bicycle frame maintain high rigidity. This local differentiation of mechanical properties allows simultaneous achievement of clamping capability and structural strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the fastening properties and rigidity of the power unit mounting structure while maintaining cost-effectiveness by allowing for lower accuracy in manufacturing and minimizing exposed parts, thus improving the overall stability and assembly efficiency of the bicycle.
Implementation Method 1
the pair of plate-like portions elastically deform as they are pressed by the head of the fixing bolt and a nut
Data Source
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AI summary
A power-assisted bicycle (1, 71, 101) includes a front wheel (10), a rear wheel (5), a body frame (6), a bracket (14) for mounting a power unit, and a power unit (15) fixed to the bracket (14) by a fixing bolt (53). The power unit (15) includes a pedal crank shaft (16) and a motor (42) for auxiliary power, and outputs each of human power applied to the pedal crank shaft (16) and driving force of the motor (42), or the resultant force of the human power and the driving force of the motor (42), to the outside. The bicycle (1, 71, 101) also includes a chain (29) for transmitting the resultant force of the human power and the driving force of the motor (42) to the rear wheel (5). The bracket (14) includes a front mounting seat (61) and rear mounting seat (62) pointing downward. The power unit (15) includes first and second front mounting portions (51, 52) and first and second rear mounting portions (55, 56) which overlap the front mounting seat (61) and rear mounting seat (62) from below. The fixing bolt (53) extends in a direction in which the front mounting seat (61) and rear mounting seat (62) and the mounting portions (51, 52, 55, 56) overlap each other, and fastens the mounting portions (51, 52, 55, 56) to the front mounting seat (61) and rear mounting seat (62). This invention can provide a power-assisted bicycle (1, 71, 101) capable of improving both the fastening properties and rigidity when mounting the power unit, while reducing the manufacturing cost.