Composite electrically insulating bicycle frame and composite material for its production

Abstract

The application relates to an electrically insulated composite bicycle frame and a prepared composite material, and relates to the technical field of electric power-assisted bicycles. The frame comprises a vehicle body, a motor is arranged on the vehicle body, an intelligent instrument is arranged at the front end of the vehicle body, and an anti-electromagnetic area is arranged between the motor and the intelligent instrument. The material corresponding to the vehicle body of the anti-electromagnetic area is a composite material. The composite material is composed of inorganic fiber cloth and carbon fiber cloth. The application prepares the composite material, so that the composite material has corresponding strength and resistance characteristics. The anti-electromagnetic area is arranged at the bicycle frame, the composite material is applied to the vehicle body of the anti-electromagnetic area, the remaining part of the vehicle body is still carbon fiber, the electromagnetic conduction path can be blocked, the electromagnetic signal generated by the motor can avoid interfering with the intelligent instrument, excessive anti-electromagnetic allowance can be avoided, and economic benefits can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrically charged power-assisted bicycles, in particular to an electrically insulated bicycle frame made of composite material and the composite material. BACKGROUND

[0002] The electrically charged power-assisted bicycle is a new type of two-wheeled vehicle, which belongs to a type of bicycle. It uses a battery as an auxiliary power source, is equipped with an electric motor, and has a power electronic system, and can realize the integration of human-powered riding and motor-assisted power. In the field of power-assisted bicycles, the installation position of the motor is mainly the hub and the middle.

[0003] The motor is connected to the frame and transmits power to the rear wheel through a belt or shaft transmission device. At the same time, pedals are installed on both sides of the motor. In the case where the motor has no power supply, the rider can realize human-powered riding through the pedals, and there is no difference in resistance from a normal bicycle.

[0004] The conventional electrically charged power-assisted bicycle frame is made of aluminum or carbon fiber, which are both conductive materials. This makes the motor of the electrically charged power-assisted bicycle conduct electromagnetic radiation during operation, which interferes with the normal operation of other electronic systems.

[0005] Therefore, the anti-interference capability of each electronic system is generally improved to avoid the electromagnetic interference conducted by the motor. However, this method makes the electronic system have much higher anti-electromagnetic interference margin than required, resulting in poor economic efficiency. SUMMARY

[0006] To solve the problem of poor economic efficiency in the process of resisting electromagnetic interference of the electrically charged power-assisted bicycle, the present application provides an electrically insulated bicycle frame made of composite material and a composite material prepared thereby. The composite material prepared has electrically insulating properties and is applied to a specific position of the bicycle frame, which blocks and insulates electromagnetic effects, and can avoid generating an anti-electromagnetic interference margin, effectively solving the problem of poor economic efficiency in the process of resisting electromagnetic interference of the electrically charged power-assisted bicycle.

[0007] In a first aspect, the present application provides an electrically insulated bicycle frame made of composite material. The frame includes a vehicle body, the vehicle body is provided with a motor, the front end of the vehicle body is provided with an intelligent instrument, and an anti-electromagnetic area is provided on the vehicle body between the motor and the intelligent instrument.

[0008] The material corresponding to the vehicle body in the anti-electromagnetic area is a composite material.

[0009] The composite material is composed of inorganic fiber woven cloth and carbon fiber.

[0010] Further, the above-mentioned anti-electromagnetic area includes a transition area and an insulating area.

[0011] The material corresponding to the vehicle body in the transition area is a composite material.

[0012] The material corresponding to the insulation area at the vehicle body is inorganic fiber cloth.

[0013] Further, the transition area includes a transition area one and a transition area two, and the transition area one, the insulation area and the transition area two are sequentially connected.

[0014] In a second aspect, the application provides a preparation method of the composite material, and the preparation method includes:

[0015] The carbon fiber cloth and the inorganic fiber cloth are pretreated.

[0016] The pretreated carbon fiber cloth and the inorganic fiber cloth are alternately stacked, and then subjected to a molding and heating treatment to obtain the composite material.

[0017] Further, the inorganic fiber cloth is basalt fiber cloth or aramid fiber cloth.

[0018] Further, the inorganic fiber cloth is basalt fiber cloth.

[0019] The pretreatment of the carbon fiber cloth and the basalt fiber cloth includes:

[0020] The carbon fiber cloth is immersed in the epoxy resin to obtain a preformed carbon cloth.

[0021] The surface modifier is applied to the basalt fiber cloth to obtain a preformed basalt cloth.

[0022] Further, the surface modifier is composed of a coupling agent and an epoxy resin, and the mass ratio of the coupling agent to the epoxy resin is (0.5-1):100.

[0023] The coupling agent is an organic silicon coupling agent.

[0024] Further, when the preformed carbon cloth and the preformed basalt cloth are alternately stacked, the fibers of the preformed carbon cloth and the preformed basalt cloth alternately present an angle of 80-90°.

[0025] Further, the molding and heating step includes:

[0026] The preformed carbon cloth and the preformed basalt cloth after the stacking are placed in a mold at 50-70°C for molding treatment.

[0027] The mold is heated to 130-160°C during the molding treatment, and the epoxy resin is hardened and formed.

[0028] In summary, the application includes at least one of the following beneficial technical effects:

[0029] 1.The application solves the problem of electromagnetic signal interference of intelligent instruments caused by the motor by preparing a composite material, the composite material has electrical insulation, an electromagnetic resistance area is arranged on an electromagnetic conduction path of a bicycle frame, the composite material is applied to a corresponding bicycle body of the electromagnetic resistance area, and the rest of the bicycle body is still made of carbon fiber to block the electromagnetic conduction path, thereby avoiding excessive electromagnetic resistance margin and improving economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a structural diagram of a bicycle frame in the embodiment of the application;

[0031] Figure 2 is a process flow diagram for preparing a composite material in the embodiment of the application;

[0032] Figure 3 is a fiber distribution diagram at a corresponding bicycle body of an electromagnetic resistance area in the embodiment of the application.

[0033] Reference signs: 1, bicycle body; 2, motor; 3, electromagnetic resistance area; 31, transition area I; 32, insulating area; 33, transition area II. DETAILED DESCRIPTION

[0034] The application will be further described in detail below in combination with embodiments. It should be particularly noted that, in the following embodiments, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturers are used; and in the following embodiments, the raw materials used can be obtained from ordinary commercial sources unless otherwise specified.

[0035] The application will be further described in detail below in combination with the accompanying Figures 1-3 The application will be further described in detail below in combination with the accompanying

[0036] The application discloses an electrically insulated bicycle frame made of a composite material, and the preparation of the composite material. The bicycle is an electric-assisted bicycle, which is between an electric vehicle and a bicycle, can realize the integration of human-powered riding and motor-assisted driving, and is a new type of popular transportation tool. The bicycle is provided with a motor and an auxiliary electronic system. The motor is used to provide additional driving force for the rider, and the auxiliary electronic system can be used to record the riding distance and speed. However, the conventional bicycle frame material is aluminum or carbon fiber, which is a conductive material, so that the motor of the electric-assisted bicycle will conduct electromagnetic radiation during work, thereby interfering with the work of other electronic systems.

[0037] The prior art generally improves the anti-interference ability of each electronic system to avoid the electromagnetic interference conducted by the motor. This method makes the electronic system have much higher electromagnetic interference resistance margin than required, and the scheme is not economical. In addition, an anti-electromagnetic composite material is used to prepare the entire frame to achieve the anti-electromagnetic effect.

[0038] The above anti-electromagnetic composite material is prepared by blending oxygen resin, E resin, basalt fiber, carbon fiber, dispersing agent, antioxidant, plasticizer, coupling agent and metal compound. However, the fiber structure of the carbon fiber and basalt fiber is destroyed during the preparation of the above material, resulting in a decrease in the strength of the material, and more plasticizers and the like need to be consumed to compensate for the defects. This method is not only expensive, but also increases the weight of the frame, reduces the lightweight effect, and has poor economic benefits.

[0039] Therefore, in the embodiments of the present application, the anti-electromagnetic area is reasonably arranged according to the structure of the bicycle frame, the material at the corresponding position of the frame is changed, the path of electromagnetic conduction is blocked by the material, and the anti-electromagnetic effect is achieved. In addition, the material composition is simple, the complete fiber structure is preserved as much as possible, and the strength of the bicycle frame is ensured. In addition, the carbon fiber is used in the remaining part of the frame except the anti-electromagnetic area, and the lightweight of the bicycle frame is still ensured.

[0040] The embodiments of the present application provide an electrically insulated bicycle frame of a composite material, which can be referred to Figure 1 . The frame includes a frame body, a motor is fixedly installed at the middle position of the frame body, an intelligent instrument is fixedly installed at the front end of the right side of the frame body, an anti-electromagnetic area is arranged on the frame body between the motor and the intelligent instrument, and the material corresponding to the anti-electromagnetic area on the frame body is a composite material. The composite material is composed of inorganic fiber cloth and carbon fiber cloth, and the materials of the remaining part of the frame body are carbon fibers. The composite material used in the embodiments of the present application has anti-electromagnetic properties, can block the electromagnetic conduction path generated by the motor, and avoid electromagnetic conduction to the intelligent instrument to interfere with the normal operation of the intelligent instrument.

[0041] The anti-electromagnetic area is arranged between the motor and the intelligent instrument because the electromagnetic intensity is strong and the conduction is fast on this path. From the structure of the frame body, the structure at this position is simple and the strength is stable, so replacing the material of this part of the frame body will not reduce the strength of the whole frame, and the anti-electromagnetic effect can be effectively achieved.

[0042] The anti-electromagnetic area includes a transition area and an insulation area, the transition area includes a first transition area and a second transition area, and the first transition area, the insulation area and the second transition area are sequentially connected. Referring to Figure 3 , the materials corresponding to the first transition area and the second transition area on the frame body are composite materials, and the material corresponding to the insulation area on the frame body is inorganic fiber cloth. The first transition area and the second transition area are connected with only the part of the carbon fiber material of the frame body, and the whole material of the frame body is more coherent by arranging the transition area, and the strength of the frame body is improved.

[0043] The preparation method of the composite material applied in the frame of the embodiments of the present application can be referred to Figure 2 and Figure 3 :

[0044] Step S1: cloth and prepreg preparation. Select the appropriate specification of carbon fiber cloth and inorganic fiber cloth according to the requirements of producing bicycle frame. The specification of carbon fiber can be selected as standard modulus (200-280 GPa), medium modulus (280-350 GPa), high modulus (350-600 GPa) and ultrahigh modulus (600+GPa). Based on economic considerations, the specification of carbon fiber is preferably standard modulus (200-280 GPa) and medium modulus (280-350 GPa). The inorganic fiber cloth is basalt fiber cloth or aramid fiber cloth, and the preferred inorganic fiber cloth is basalt fiber cloth. In addition to good insulation, basalt fiber cloth can further improve the strength and stiffness of the composite material when combined with carbon fiber cloth. The combination of basalt fiber cloth and carbon fiber cloth can reduce the density of the composite material and achieve the effect of lightweight. Basalt fiber cloth and carbon fiber cloth both have good high temperature resistance, and the combination of the two can exhibit better stability and heat resistance in high temperature environment. Compared with pure carbon fiber cloth, the combination of basalt fiber cloth and carbon fiber cloth can reduce the cost of the material and achieve cost effectiveness. The thermal expansion coefficient of aramid fiber cloth and carbon fiber cloth is quite different, and the stability is poor when combined in a high temperature environment, which is prone to cracking. The price of aramid fiber is high, which is difficult to improve cost effectiveness. Therefore, basalt fiber cloth is preferred.

[0045] Cut the carbon fiber cloth and basalt fiber cloth into the specified shape according to the product and mold requirements for subsequent stacking and molding process. It should be noted that the cross angle requirement should be considered when cutting to save materials.

[0046] Prepare epoxy resin and surface modifier. The amount of epoxy resin is sufficient to soak the carbon fiber cloth, that is, the carbon fiber cloth can be completely immersed in the epoxy resin. The amount of surface modifier is to evenly apply a hardening layer with a thickness of 1-3mm on the basalt fiber cloth.

[0047] The coupling agent is an organosilicon coupling agent, which is selected from any one of methyltrichlorosilane (MTS), aminosilane (AMO), vinylsilane (VTS), epoxy silane (EPS) and allyltrimethoxysilane (VTMS). The preferred organosilicon coupling agent is selected from any one of methyltrichlorosilane, vinylsilane and allyltrimethoxysilane. Further preferably, the organosilicon coupling agent is allyltrimethoxysilane. Allyltrimethoxysilane is a silane coupling agent containing an allyl group, which can cross-link with organic matter containing active hydroxyl groups to prepare a composite material with strong durability and chemical stability.

[0048] The mass ratio of the above-mentioned allyl trimethoxysilane and epoxy resin is (0.5-1):100, and the preferred mass ratio of the allyl trimethoxysilane and epoxy resin is 0.7:100. The epoxy resin and the allyl trimethoxysilane are stirred with an electric mixer, and the surface modifier is prepared after the stirring is uniform.

[0049] Step S2: Pretreatment. The carbon fiber fabric is immersed in the epoxy resin to make it fully and uniformly distributed on the carbon fiber fabric, so as to improve the flexibility and durability of the carbon fiber fabric. The immersion method helps the carbon fiber fabric to be better combined with the epoxy resin. After immersion, the preformed carbon cloth is obtained.

[0050] The surfactant prepared in step S1 is uniformly applied to the basalt fiber fabric, and the thickness of the application is preferably 2 mm. The surface of the basalt fiber fabric is modified to enhance the adhesion between the basalt fiber fabric and the carbon fiber fabric, so that the basalt fiber fabric is more easily combined with the carbon fiber fabric. After application, the preformed basalt cloth is obtained.

[0051] Step S3: Prepare the mold. The mold is cleaned with a mold cleaning agent to ensure that the surface of the mold is clean and smooth, and to avoid the influence of impurities on the finished product. After cleaning, a mold release agent is applied to the surface of the mold to prevent sticking and facilitate the removal of the finished product.

[0052] Step S4: Stack the fabric. The preformed carbon cloth and the preformed basalt cloth are alternately stacked in the mold without applying a mold release agent. The fiber orientation and the number of layers can be adjusted according to the design requirements of the product during stacking. The fiber orientation of the preformed carbon cloth and the preformed basalt cloth alternately presents 80-90°, and preferably, the fiber orientation of the preformed carbon cloth and the preformed basalt cloth alternately presents 90°, so as to enhance the strength and stability of the finished product. It is noted that the stacking is performed according to the pre-cut shape, so as to effectively utilize the materials and reduce waste.

[0053] Step S5: Exhaust and pump. After the stacking is completed, the excess epoxy resin, surfactant and air bubbles are extracted using a micro-negative pressure vacuum tool, so that the preformed carbon cloth and the preformed basalt cloth are more easily combined, and the occurrence of voids in the finished product is reduced. The above-mentioned micro-negative pressure vacuum tool is a medium-high viscosity liquid pump.

[0054] Step S6: Molding Heating. Heat the mold coated with a release agent to 50-70℃. Specifically, the mold can be heated to 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃, or 70℃. Preferably, the mold is heated to 60℃. Place the degassed and stacked precast carbon cloth and precast basalt cloth into the mold heated to 60℃ and coated with a release agent. Then close the mold and apply pressure to ensure the two materials are tightly bonded and to further remove air bubbles. Continue heating the mold during molding to a predetermined hardening temperature of 130-160℃, preferably 150℃, to allow the epoxy resin and surfactant to harden. The molded precast carbon cloth and precast basalt cloth are formed as the epoxy resin and surface modifier harden, resulting in a composite material.

[0055] Step S7: Cooling and Mold Opening. After the composite material is obtained, the mold is placed in a cooling chamber to cool. Once the temperature is lower than the mold opening temperature, the mold is opened and the composite material is removed.

[0056] Step S8: Inspection and Post-processing. Finally, inspect the quality of the composite material and remove any burrs. Surface treatments such as sanding, machining, and painting may be performed if necessary. After processing, the finished composite material is obtained.

[0057] The manufacturing process of the bicycle frame is as follows: the insulation area is woven, soaked, shaped, and molded using basalt fiber weaving technology, while transition areas one and two are made of the composite material prepared above. The insulation area, transition area one, transition area two, and other areas of the bicycle frame are properly arranged during the molding process and then integrally formed to obtain the bicycle frame.

[0058] The aforementioned composite materials and the manufacturing process of the vehicle frame have advantages such as short molding time, simple process, and high strength. The resulting vehicle frame can achieve insulation in the conduction path, preventing electromagnetic interference with the normal operation of the system and greatly improving economic efficiency.

[0059] Example

[0060] Example 1

[0061] Preparation of a composite material:

[0062] 1. Stir 1 kg of epoxy resin and 70 g of organosilicon coupling agent until they are evenly mixed to obtain a surface modifier;

[0063] 2. Impregnate the carbon fiber fabric in epoxy resin to obtain prefabricated carbon cloth. Apply a surface modifier evenly to the surface of the basalt fiber fabric to obtain prefabricated basalt cloth.

[0064] 3. Clean the mold with mold cleaning agent, and after cleaning, coat a layer of mold release agent on the surface of the mold, then stack the preformed carbon cloth and the preformed basalt cloth in the mold, so that the fibers of the preformed carbon cloth and the preformed basalt cloth are alternately arranged at 90°;

[0065] 4. Place the stacked preformed carbon cloth and preformed basalt cloth in the mold with a temperature of 60°C and coated with a mold release agent, and perform mold closing and pressurization, and simultaneously continuously heat the mold to a hardening temperature of 150°C, and after the epoxy resin and the surface modifier are hardened, a molded composite material is obtained;

[0066] 5. After cooling the mold to the mold opening temperature, remove the composite material, and after inspection and deburring, the finished composite material is obtained.

[0067] A carbon fiber and the above composite material are used to prepare an electrically insulated bicycle frame, wherein the transition region I and the transition region II of the bicycle frame are made of the composite material, the insulating region is made of basalt fiber woven cloth, and the parts of the frame other than the transition region I, the insulating region and the transition region II are made of carbon fiber woven cloth.

[0068] A set of Comparative Example 1 is set according to the above Example 1, and the difference between Comparative Example 1 and Example 1 is that the composite material and the basalt fiber woven cloth are not used, and the bicycle frame is made of carbon fiber woven cloth.

[0069] Another set of Comparative Example 2 is set according to Comparative Example 1, and the difference between Comparative Example 2 and Comparative Example 1 is that the anti-interference device is installed on the intelligent instrument of the bicycle frame.

[0070] The electromagnetic performance of the intelligent instrument on the frame prepared by Example 1 and Comparative Examples 1-2 is investigated, and the detection method is: electromagnetic compatibility test, electromagnetic interference detection equipment and electromagnetic interference generation equipment are used to investigate the electromagnetic compatibility of the intelligent instrument, and the electromagnetic interference generation equipment is the motor on the bicycle frame, and EN15194:2017 Annex C, FCC Part 15B Class B is used as the detection standard, and the detection results are shown in Table 1.

[0071] Table 1. Electromagnetic compatibility rating results

[0072] Electromagnetic compatibility test results Example 1 Pass Comparative Example 1 Fail Comparative Example 2 Pass

[0073] Conclusion: Comparative Examples 1 and 2 can pass the detection standard, which proves that the frame prepared by the composite material prepared by Example 1 has good electromagnetic resistance, so that the intelligent instrument on the frame can stably operate without electromagnetic interference. It can also be explained that the anti-electromagnetic region is set between the motor and the intelligent instrument on the frame, which can block the electromagnetic conduction path, so that the intelligent instrument has the effect of resisting electromagnetic interference and does not produce excess anti-electromagnetic interference, and the economic benefit is better.

[0074] The bicycle in Comparative Example 1 is made of carbon fiber, and the intelligent instrument on the bicycle made of the carbon fiber has weak anti-magnetic performance and cannot reach the basic level, which further proves that the bicycle made of the composite material of Example 1 and the carbon fiber fabric has good anti-electromagnetic performance.

[0075] Two groups of comparative examples are set according to Example 1, which are Comparative Example 3 and Comparative Example 4.

[0076] Comparative Example 3

[0077] The difference between Comparative Example 3 and Example 1 is that the bicycle frame made of Comparative Example 3 is not provided with a transition zone, and only an insulation zone is provided at the bicycle body between the motor and the intelligent instrument.

[0078] Comparative Example 4

[0079] The difference between Comparative Example 4 and Example 1 is that the bicycle frame of Comparative Example 4 is not provided with an insulation zone, and only a transition zone is provided at the bicycle body between the motor and the intelligent instrument.

[0080] The fatigue strength and impact strength of the bicycle frames prepared by Example 1 and Comparative Examples 3-4 are investigated, wherein the test method of the fatigue strength is: cycle 1100N (112Kg) / 100000, frequency: 3.0Hz, which meets the standard EN147814.8.4; the test method of the impact strength is falling from 212mm height with 22.5kg permanent deformation less than 10mm, which meets the standard EN147814.8.2, and the detection results are shown in Table 2 below.

[0081] Table 2. Physical property test results

[0082] Fatigue strength Impact strength Example 1 Pass Pass Comparative Example 3 Fail Fail Comparative Example 4 Pass Pass

[0083] Conclusion: The fatigue strength and impact strength of the bicycle frame prepared by the composite material of Example 1 meet the standard, while the bicycle frame of Comparative Example 4 also meets the standard, but it has no insulation zone and has relatively poor anti-electromagnetic effect. Comparative Example 3 does not set a transition zone, and its physical properties do not meet the standard, which proves that setting a transition zone is helpful to improve the physical properties of the bicycle frame, and setting a transition zone and an insulation zone is better in terms of comprehensive anti-electromagnetic effect.

[0084] The above are preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the basis of the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. An electrically insulating bicycle frame of composite material, characterized in that: The frame comprises a vehicle body, a motor is arranged on the vehicle body, an intelligent instrument is arranged at the front end of the vehicle body, an anti-electromagnetic area is arranged between the motor and the intelligent instrument on the vehicle body; The anti-electromagnetic area comprises a transition area I, an insulation area and a transition area II connected in sequence, the material of the transition area I and the transition area II corresponding to the vehicle body is a composite material with anti-electromagnetic property, the material of the insulation area corresponding to the vehicle body is inorganic fiber cloth, and the material of the rest of the vehicle body is carbon fiber; The preparation method of the composite material comprises: The carbon fiber cloth is immersed in epoxy resin to obtain a pre-prepared carbon cloth; A surface modifier composed of a coupling agent and the epoxy resin is applied to the basalt fiber cloth to obtain a pre-prepared basalt cloth, the mass ratio of the coupling agent to the epoxy resin is (0.5-1):100; The pre-processed carbon fiber cloth and the pre-prepared basalt cloth are alternately stacked, the fiber directions of the two are alternately 80-90°, and then the composite material is prepared after mold pressing and heating treatment.

2. The electrically insulated bicycle frame of composite material according to claim 1, characterized in that, The coupling agent is an organic silicon coupling agent.

3. The electrically insulated composite bicycle frame of claim 1, wherein, The mold pressing and heating step comprises: The pre-prepared carbon cloth and the pre-prepared basalt cloth after stacking are arranged in a mold at 50-70℃ for mold pressing treatment; The mold is heated to 130-160℃ during the mold pressing treatment, and the epoxy resin and the surface modifier are hardened and formed.

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