Wide-width multi-cavity integrated lightweight design method for high-rigidity aluminum pedal of electric bicycle

Abstract

The invention discloses a wide-width multi-cavity integrated lightweight design method for a high-rigidity aluminum pedal of an electric bicycle. The pedal is formed by integrally extruding aluminum alloy, the integral wall is thin, the upper part is a panel, the lower part is a bottom plate, and the bottom plate is connected with a vertical rib to form a multi-cavity closed structure or a T-shaped rib is connected with a reinforcing cross beam; through holes are formed in four corners of the pedal plate, and connecting columns matched with the through holes in size penetrate through the through holes and are welded and fixed; the panels are all in an upwards-arched arc shape, a plurality of anti-skid lines are arranged on the upper surfaces of the panels, and arc-shaped covered edges are arranged on the two sides of the panels. The aluminum alloy extrusion integrated forming technology is adopted, traditional plastic extrusion or metal plate stamping is replaced, unification of light weight, high corrosion resistance and low-cost production is achieved, and the defects that a traditional plastic pedal is low in rigidity, prone to deformation, prone to aging, inflammable and not environmentally friendly, and a metal plate stamping die is high in cost are fundamentally overcome; and diversified requirements of the industry can be quickly responded, and preemptive preemption in the market environment of quick development of the electric bicycle is facilitated.

Description

Technical Field

[0001] This invention relates to the field of electric bicycle technology, specifically to a method for designing a lightweight, integrated, wide-cavity aluminum pedal with high rigidity for electric bicycles. Background Technology

[0002] my country is the world's largest producer, seller, and user of electric bicycles, with sales exceeding 60 million units by 2025, accounting for 70-80% of the global market share. Electric bicycles commonly use a large amount of plastic in structural and decorative components to meet consumers' personalized aesthetic demands. However, because plastic is flammable, these materials can accelerate the spread of fire and release large amounts of toxic gases in the event of a fire, seriously threatening people's lives and property in recent years. The pedals of electric bicycles, as crucial support components for resting the feet to control the vehicle's balance and assist in riding, directly affect riding comfort, safety, and overall vehicle performance due to their design quality. Currently, mainstream electric bicycle pedals primarily employ the following two manufacturing processes: 1. Injection Molding Process: Plastic or nylon is molded in a mold through injection molding. Foot pedals produced by this process are simple to manufacture, have low cost, and are lightweight; however, the material has low strength and rigidity, weak load-bearing capacity, and is easy to deform; and plastic parts will age, discolor, or even crack after long-term use; they are flammable and difficult to recycle, which goes against the trend of green environmental protection and safe development.

[0003] 2. Sheet metal stamping process: This process uses stamping equipment to form metal sheets in one go. However, this process requires a high investment in molds, and to ensure structural rigidity, the material thickness often needs to be increased, leading to an increase in the weight of the parts, which runs counter to the trend of lightweight development of electric bicycles. If steel plates are used, they also have the disadvantage of being prone to corrosion.

[0004] On the other hand, the "Safety Technical Specification for Electric Bicycles" GB 17761-2024, released on December 31, 2024 and implemented on September 1, 2025, imposes stricter requirements on the overall weight of electric bicycles and the proportion of plastic parts used: "The total mass of plastics used in electric bicycles should not exceed 5.5% of the total vehicle weight," and "The total weight of a fully assembled electric bicycle using lead-acid batteries should be less than or equal to 63 kg, and the total weight of other types of fully assembled electric bicycles should be less than or equal to 55 kg." This brings new opportunities and challenges to lightweight design and material innovation. The industry urgently needs a pedal solution that can balance structural strength, environmental friendliness, lightweight, corrosion resistance, and production efficiency.

[0005] In conclusion, existing electric bicycle pedal manufacturing technology can no longer meet current regulatory requirements, and there is still considerable room for improvement in material selection, process routes, and structural design. In particular, there is no good solution that balances key indicators such as flame retardancy, lightweighting, corrosion resistance, and production efficiency. This fails to meet the industry's demands for diversification, rapid response, and low cost, which is detrimental to the rapid development of the electric bicycle industry. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a lightweight, integrated, multi-cavity aluminum pedal design method for electric bicycles. Utilizing aluminum alloy extrusion molding technology, it replaces traditional plastic extrusion or sheet metal stamping, achieving a balance between lightweight design, high corrosion resistance, and low-cost production. This fundamentally solves the shortcomings of traditional plastic pedals (low environmental friendliness, low strength, easy deformation, easy aging, and flammability) and sheet metal pedals (high stamping die costs). The invention proposes a wide-cavity, multi-cavity, T-rib integrated aluminum extrusion pedal structure. Through topology optimization technology (finite element analysis), the wall thickness, cavity layout, and rib configuration are meticulously designed to achieve optimal wall thickness and material distribution. This significantly reduces weight while maintaining the required rigidity and strength of the pedal, resolving the contradiction between lightweight design and structural performance. This improves product reliability, simplifies the production process, and enhances appearance quality, achieving comprehensive optimization in multiple aspects. It offers significant advantages in cost control and production flexibility, enabling rapid response to diverse industry demands and allowing for a competitive edge in the rapidly developing electric bicycle market.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A method for designing a high-rigidity aluminum pedal for electric bicycles with a wide, multi-cavity, integrated, lightweight design. The pedal is made of aluminum alloy through integral extrusion molding, with a panel on top and a base plate on the bottom. The panel and base plate are connected by several vertical ribs to form a multi-cavity closed structure in the middle. Each of the four corners of the pedal has a through hole, through which a matching connecting post is inserted and welded in place. Several weight-reducing holes are machined on the base plate.

[0008] The foot pedal can also be designed as an open structure with sheet metal reinforcement. It is also made of aluminum alloy through integral extrusion molding. The upper part is a panel, and several T-shaped ribs are set on the bottom surface of the panel. Several reinforcing crossbeams are installed at the bottom of the T-shaped ribs. There are through holes at the four corners of the foot pedal. Connecting columns of the same size are inserted through the through holes and welded and fixed. Buckles are set at the matching installation positions of the reinforcing crossbeams and T-shaped ribs. The horizontal part of the T-shaped ribs is inserted into the buckles and then welded and fixed.

[0009] Both types of foot pedals have an arched panel with several anti-slip textures on the upper surface, and both sides of the panel have an arc-shaped edging.

[0010] The extrusion molding of foot pedals includes the following steps: S1. Heat the extrusion cylinder, aluminum alloy round ingot and mold. The heating temperature of the extrusion cylinder is 420-450℃, the heating temperature of the aluminum alloy round ingot is 480-520℃, and the heating temperature of the mold is 450-490℃. S2. Extruding aluminum alloy round ingots to obtain foot pedal profiles at an extrusion speed of 8-12 m / min; S3. The foot pedal profile is subjected to offline quenching at a temperature of 500-550℃, with a furnace temperature deviation of ±1.5℃ and a cooling intensity of 10℃-70℃ / s. S4. Return the foot pedal profile to online stretching and straightening, with a stretching rate of 0.3% to 1%; S5. Cut the stretched foot pedal profile to length. S6. Aging the sawn foot pedal profile at an aging temperature of 180±5℃ for 10 hours. S7. After aging, the foot pedal profile is shaped and its form and position tolerances and dimensional tolerances are inspected. After passing the inspection, the finished foot pedal profile is obtained.

[0011] By adopting aluminum alloy integral extrusion molding technology, the foot pedal profiles are wide, thin-walled, and highly dimensionally accurate, replacing traditional steel welding or sheet metal stamping. This achieves a balance between lightweight design, high corrosion resistance, and low-cost production, fundamentally solving industry pain points such as "low environmental friendliness, low strength, easy deformation, easy aging, and flammability" and "high cost of sheet metal stamping dies" in traditional plastic foot pedals. The offline quenching process utilizes the country's first "Automotive Aluminum Alloy Roller Hearth Continuous Heat Treatment Furnace Equipment Production Line." Compared to traditional online quenching equipment, this offline quenching equipment boasts advantages such as strong quenching capacity, low quenching stress, and good longitudinal bending properties. The dimensional tolerances and mechanical properties of the quenched foot pedal profiles are superior to those of traditional online quenching.

[0012] The connection design between the vertical ribs and the base plate or the T-shaped ribs and the reinforcing beams significantly improves the structural rigidity of the foot pedal. Furthermore, the wall thickness, cavity layout, and rib configuration are refined through topology optimization technology (finite element analysis), achieving the optimal distribution of wall thickness and material. Combined with several weight-reducing holes, the required rigidity and strength of the foot pedal are ensured while significantly reducing weight, thus resolving the contradiction between lightweighting and structural performance.

[0013] The pedal panel surface is designed with anti-slip texture. By increasing the roughness of the pedal surface, the friction between the sole of the foot and the pedal is improved, preventing the foot from slipping due to wet roads or sudden acceleration / braking, thus ensuring riding safety.

[0014] The curved edges on both sides of the foot pedal panel are not only aesthetically pleasing, but also allow rainwater to slide directly and quickly to the ground, effectively preventing rainwater from seeping into the frame and causing corrosion to the internal structure.

[0015] The foot pedal panel has through holes at all four corners. After matching with the connecting post, it is simply welded together. After welding, it is threadedly connected and fixed to the frame through the threaded holes machined inside the connecting post. The connection method is simple, quick, stable and reliable.

[0016] This invention improves product reliability and appearance quality, achieving comprehensive optimization in multiple aspects. It offers significant advantages in cost control and production flexibility, and from a market application perspective, this patented technology has broad promotional value. Firstly, it directly aligns with the industry requirements of the "Electric Bicycle Safety Technical Specification" GB 17761-2024 regarding overall lightweighting of electric bicycles and the replacement of plastics with aluminum, providing an ideal technical solution for vehicle manufacturers. Secondly, the aluminum extrusion molding process is more flexible, and aluminum extrusion molds are relatively cheaper, enabling companies to develop a series of differentiated products at a lower cost, quickly responding to market changes and gaining a competitive edge in the rapidly developing electric bicycle market. Furthermore, this technology can be extended to other personal mobility tools such as electric motorcycles and electric scooters, offering broad application prospects.

[0017] Advantages of the invention: 1. Material and Process Innovation: This invention adopts aluminum alloy extrusion molding technology to replace traditional injection molding or sheet metal stamping, achieving a balance between lightweight, high corrosion resistance, and low-cost production. It fundamentally solves the shortcomings of traditional foot pedals, such as "low environmental friendliness, low strength, easy deformation, easy aging, and flammability," as well as the high cost of stamping molds for sheet metal foot pedals. This process is particularly suitable for the electric bicycle industry's demand for diversification, fast response, low cost, and high flame retardancy, which is conducive to seizing the initiative in the rapidly developing electric bicycle market.

[0018] 2. Innovative Structural Design: This invention uses topology optimization technology (finite element analysis) to refine the design of wall thickness, cavity layout and stiffener configuration, achieving the optimal distribution of wall thickness and materials. While significantly reducing weight, it ensures the required stiffness and strength of the foot pedal, resolving the contradiction between lightweighting and structural performance.

[0019] 3. Integrated Innovation: This invention eliminates the weak points of traditional splicing structures through an integrated design, improves product reliability, simplifies the production process, improves appearance quality, and achieves comprehensive optimization in many aspects. Attached Figure Description

[0021] Figure 1This is an elevation view of Embodiment 1 of the present invention; Figure 2 This is a left view of Embodiment 1 of the present invention; Figure 3 This is a bottom view of Embodiment 1 of the present invention; Figure 4 for Figure 2 Enlarged structural diagram at point I; Figure 5 This is a deformation cloud diagram from the finite element analysis of Embodiment 1 of the present invention; Figure 6 This is a stress cloud diagram from the finite element analysis of Embodiment 1 of the present invention; Figure 7 This is an elevation view of Embodiment 2 of the present invention; Figure 8 This is a cross-sectional view of the reinforcing beam in Embodiment 2 of the present invention; Figure 9 This is a deformation cloud diagram from the finite element analysis of Embodiment 2 of the present invention; Figure 10 This is a stress cloud diagram from the finite element analysis of Embodiment 2 of the present invention; Figure 11 This is a deformation cloud diagram from the finite element analysis of the non-welded crossbeam on the bottom surface in Embodiment 2 of the present invention. The numbers and component names in the diagram are as follows: 1-Panel; 11-Anti-slip texture; 2-Vertical rib; 3-Base plate; 4-T-shaped rib; 5-Weight reduction hole; 6-Arched edging; 7-Connecting column; 8-Reinforcing beam; 81-Snap fastener. Detailed Implementation

[0022] To provide a more detailed description of the present invention, the following description is provided in conjunction with embodiments and accompanying drawings.

[0023] Example 1

[0024] like Figure 1-4 As shown, a high-rigidity aluminum pedal for an electric bicycle has a wide, multi-cavity integrated structure. The pedal is made of aluminum alloy through integral extrusion molding, with alloy grade and temper being 6082-T6. The main wall thickness ranges from 1.5 to 2.0 mm. The upper part is a panel 1, and the lower part is a base plate 3. The panel 1 and the base plate 3 are connected by several vertical ribs 2 to form a multi-cavity closed structure in the middle. Each of the four corners of the pedal is provided with a through hole, through which a matching connecting post 7 is inserted and welded to fix it.

[0025] Several weight-reducing holes 5 are machined on the base plate 3.

[0026] The panel 1 is an upwardly arched arc shape, and arc-shaped edging 6 is provided on both sides of the panel 1.

[0027] The upper surface of the panel 1 is provided with several anti-slip textures 11.

[0028] The extrusion molding of the foot pedal includes the following steps: S1. Heat the extrusion cylinder, aluminum alloy round ingot and mold. The heating temperature of the extrusion cylinder is 440℃, the heating temperature of the aluminum alloy round ingot is 500℃, and the heating temperature of the mold is 490℃. S2. Extruding aluminum alloy round ingots to obtain foot pedal profiles at an extrusion speed of 10m / min; S3. The foot pedal profile is subjected to offline quenching at a temperature of 525℃, with a furnace temperature deviation of ±1.5℃ and a cooling rate of 50℃ / s. The tensile strength of the quenched aluminum foot pedal profile can reach 400MPa, the yield strength is ≥260MPa, and the Brinell hardness is ≥95 HBW, which is significantly higher than that of conventional 6061-T6 alloy (tensile strength is about 290 MPa). S4. Return the foot pedal profile to online stretching and straightening, with a stretch rate of 0.8%; S5. Cut the stretched foot pedal profile to length. S6. Aging the sawn foot pedal profile at an aging temperature of 180±5℃ for 10 hours. S7. After aging, the foot pedal profile is shaped and its form and position tolerances and dimensional tolerances are inspected. After passing the inspection, the finished foot pedal profile is obtained.

[0029] like Figure 5-6 As shown, when a pressure of 7500N is applied, the surface of the foot pedal panel 1 has a deformation of ≤1.28mm and a stress of ≤296.1Mpa, as obtained by finite element analysis.

[0030] Example 2

[0031] like Figure 7-8 As shown, a high-rigidity aluminum pedal for an electric bicycle has a wide, multi-cavity integrated structure. The pedal is made of aluminum alloy through integral extrusion molding, with the alloy grade and temper being 6082-T6. The main wall thickness ranges from 1.5 to 2.0 mm. The upper part is a panel 1, and several T-shaped ribs 4 are provided on the bottom surface of the panel 1. Several reinforcing crossbeams 8 are installed at the bottom of the T-shaped ribs 4. Through holes are provided at the four corners of the pedal, and connecting posts 7 of matching size are inserted through the through holes and welded and fixed.

[0032] The reinforcing beam 8 and the T-shaped rib 4 are matched with a buckle 81 at the installation position. The horizontal part of the T-shaped rib 4 is inserted into the buckle 81 and then welded and fixed.

[0033] The panel 1 is an upwardly arched arc shape, and arc-shaped edging 6 is provided on both sides of the panel 1.

[0034] The upper surface of the panel 1 is provided with several anti-slip textures 11.

[0035] The foot pedal extrusion molding steps and process parameters are the same as in Example 1.

[0036] like Figure 9-10 As shown, the foot pedal has an open sheet metal structure. After several crossbeams are welded to the bottom surface, the surface of panel 1, under a pressure of 7500N, shows a deformation ≤1.43mm and a stress ≤664.3Mpa through finite element analysis. Figure 11 As shown, if the crossbeam is not welded to the bottom surface, the maximum deformation of panel 1 surface under a pressure of 7500N is 3.07mm, an increase of 1.15 times, as determined by finite element analysis. Therefore, when using this design, a crossbeam must be welded to the bottom surface to enhance its structural strength. Compared to Example 1, Example 2 has a reduced extrusion die difficulty, significantly reduced machining time, improved yield of foot pedal profiles, and shorter production costs and cycles. However, welding itself can cause defects such as structural deformation and stress concentration.

[0037] In summary, the two pedal designs of this invention have numerous advantages over traditional injection-molded or sheet metal stamped pedals, including high strength, resistance to deformation, resistance to aging, corrosion resistance, short production cycle, low cost, and environmental friendliness. These advantages make it easier to gain a competitive edge in the rapidly developing electric bicycle market.

Claims

1. A high-rigidity aluminum pedal with a wide, multi-cavity integrated structure for electric bicycles, characterized by: The foot pedal is made of aluminum alloy integral extrusion molding. The upper part is the panel (1) and the lower part is the base plate (3). The panel (1) and the base plate (3) are connected by several vertical ribs (2) to form a multi-cavity closed structure in the middle. The four corners of the foot pedal are provided with through holes, and the connecting columns (7) of the matching size are inserted into the through holes and welded and fixed.

2. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1, characterized in that: Several weight-reducing holes (5) are machined on the base plate (3).

3. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1, characterized in that: The foot pedal is made of aluminum alloy integral extrusion molding. The upper part is a panel (1). Several T-shaped ribs (4) are set on the bottom surface of the panel (1). Several reinforcing crossbeams (8) are installed at the bottom of the T-shaped ribs (4). The four corners of the foot pedal are provided with through holes. Connecting columns (7) of matching size are inserted through the through holes and welded and fixed.

4. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1, characterized in that: The reinforcing beam (8) and the T-shaped rib (4) are matched with a buckle (81) at the installation position. The horizontal part of the T-shaped rib (4) is inserted into the buckle (81) and then welded and fixed.

5. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1 or 3, characterized in that: The panel (1) is an upward arched arc shape, and arc-shaped edging (6) is provided on both sides of the panel (1).

6. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1 or 3, characterized in that: The upper surface of the panel (1) is provided with several anti-slip textures (11).

7. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1 or 3, characterized in that, The extrusion molding of the foot pedal includes the following steps: S1. Heat the extrusion cylinder, aluminum alloy round ingot and mold. The heating temperature of the extrusion cylinder is 420-450℃, the heating temperature of the aluminum alloy round ingot is 480-520℃, and the heating temperature of the mold is 450-490℃. S2. Extruding aluminum alloy round ingots to obtain foot pedal profiles at an extrusion speed of 8-12 m / min; S3. The foot pedal profile is subjected to offline quenching at a temperature of 500-550℃, with a furnace temperature deviation of ±1.5℃ and a cooling intensity of 10℃-70℃ / s. S4. Return the foot pedal profile to online stretching and straightening, with a stretching rate of 0.3% to 1%; S5. Cut the stretched foot pedal profile to length. S6. Aging the sawn foot pedal profile at an aging temperature of 180±5℃ for 10 hours. S7. After aging, the foot pedal profile is shaped and its form and position tolerances and dimensional tolerances are inspected. After passing the inspection, the finished foot pedal profile is obtained.

8. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 1, characterized in that: When a pressure of 7500N is applied, the surface of the foot pedal panel (1) is subjected to a deformation of ≤1.28mm and a stress of ≤296.1Mpa, as determined by finite element analysis.

9. The high-rigidity aluminum pedal wide-cavity integrated structure for electric bicycles according to claim 3, characterized in that: The foot pedal is an open structure with sheet metal reinforcement. After several crossbeams are welded to the bottom surface, the deformation of the panel (1) surface under a pressure of 7500N is ≤1.43mm and the stress is ≤664.3Mpa, as determined by finite element analysis. However, if the crossbeams are not welded to the bottom surface, the maximum deformation of the panel (1) surface under a pressure of 7500N is 3.07mm, which is 1.15 times greater, as determined by finite element analysis.

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