Automobile headlight outer lens with anti-sag and anti-fog functions, automobile headlight and preparation method thereof

Abstract

The present invention relates to an outer lens of a vehicle headlamp with anti-sag and anti-fog functions, an automotive headlamp, and a preparation method thereof. The inventor deeply analyzed the reasons for sagging in automotive headlamps from aspects such as materials and structures, and improved the anti-fog paint spraying tooling fixture starting from the spraying process. By adopting a semi-spraying method, a blank area is formed at the upper position on the inner surface of the outer lens of the vehicle headlamp with the help of a baffle, and an anti-fog coating area is formed at other positions. The existence of the blank area avoids the dissolution of the anti-fog paint by the supersaturated water vapor accumulated at the top of the inner surface of the outer lens of the vehicle headlamp, causing sagging, and the anti-fog coating area can play a good anti-fog role. This solution does not require the design of complex de-fogging structures such as ventilation and drying, and does not require great efforts to research and develop improved anti-fog coating materials, and has the advantages of low cost and good effect.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive lighting, and particularly to an outer lens of a vehicle lamp, a vehicle lamp and a preparation method thereof, which have the functions of preventing sagging and preventing fogging. Background Art

[0002] The outer lens of an automotive headlamp is a transparent protective structure located on the outermost part of the headlamp, which plays multiple roles such as transmitting light, isolating the external environment, and protecting the components inside the lamp cavity. During the use of the outer lens of the headlamp, water vapor will inevitably enter the lamp cavity. Due to the large temperature difference between the inside and outside of the lamp cavity, the water vapor will gradually condense into water mist or water droplets on the inner surface of the outer lens, seriously affecting the light transmittance and appearance of the headlamp.

[0003] To overcome this problem, an anti-fog coating is usually sprayed on the inner surface of the existing outer lens of the headlamp. All the common anti-fog paints used to form the anti-fog coating on the market are hydrophilic materials. Although the anti-fog coating can effectively absorb the water vapor inside the headlamp to prevent it from condensing into water mist, with the prolongation of the use time or under the influence of other factors (such as high external environmental humidity, large temperature difference, or reduced sealing performance of the headlamp, etc.), after the anti-fog coating on the inner surface of the outer lens accumulates a large amount of water vapor and reaches saturation, it will then dissolve and fall off and move downward along the inner surface of the outer lens under the action of gravity, forming a permanent "tear-shaped" sag. The appearance of the sag phenomenon not only makes the anti-fog coating lose its anti-fog effect, but also seriously affects the appearance and lighting effect of the automotive headlamp and driving safety. The problem of headlamp sag has become a difficult problem in the automotive lighting industry and must be solved.

[0004] One solution is to improve the anti-fog coating material, but so far no major breakthrough has been achieved. Currently, all the anti-fog paints for the outer lens of headlamps on the market basically have the problem of sag. Qian Juan et al. (CN108679576A) coated a nano-hydrophobic layer on the inner surface of the xenon headlamp to make the water vapor spread evenly on its surface, and then cooperated with a certain number of heating sheets, ventilation holes, humidity sensors and other devices for dynamic detection and adjustment to prevent the inner wall of the headlamp from fogging. However, this solution not only has a complex structure and high cost, but also the nano-hydrophobic layer will inevitably fail, fall off and flow down with the water under the repeated action of high temperature and water vapor, and the sag phenomenon will only be more obvious.

[0005] Another solution is to start from the headlight structure and install an anti-fogging system in the headlight with extremely limited space. Wang Hongju et al. (CN107654982A) designed complex air inlet and outlet channels and desiccants in the headlight to prevent fogging in the lamp cavity and thus avoid the phenomenon of running down. Similar solutions also include the Chinese patent CN108397742A disclosed by Ding Junhua et al. These solutions generally have problems such as poor applicability, high cost, and complex processes, and it is difficult to promote and apply them on a large scale. Zhang Guobao et al. (CN206072915U) effectively solved the problems of headlight fogging and the resulting running down, flowing marks, failure, discoloration, etc. through two overlapping lenses and a vacuum tight structure between the lenses. However, the double-layer lenses in this method have problems such as decreased light transmittance and low light utilization rate, and it is difficult to meet the requirements of automotive lighting regulations. In addition, the double lenses and the intermediate vacuum will greatly increase the manufacturing and production costs of the headlight, and it is also very difficult to ensure the long-term reliability and stability of the vacuum.

[0006] Based on a large number of analysis and experiments on the existing technology, the present invention has achieved good results by means of ingenious improvements, solving the problems of anti-fogging and anti-running down inside the headlight with the lowest cost and the simplest structure. Summary of the Invention

[0007] One object of the present invention is to provide an outer lens of a headlight with anti-running down and anti-fogging functions. An anti-fogging coating area and a blank area (without spraying anti-fog paint) are provided on the inner surface of the outer lens of the headlight, and the blank area is located at the upper position of the inner surface of the outer lens of the headlight (viewing angle when the outer lens of the headlight is in the installed state).

[0008] Further, the blank area is in the shape of an elongated strip and is horizontally arranged along the top of the inner surface of the outer lens of the headlight, or is inclined along the top contour of the inner surface of the outer lens of the headlight.

[0009] Furthermore, the widths at both ends of the blank area are smaller than the width in the middle of the blank area. The possibility and severity of the running down phenomenon in the middle of the outer lens of the headlight are the highest, so it is necessary to ensure that the blank area at this part is large enough to achieve better anti-fogging and anti-running down effects.

[0010] Further, a hardening coating (such as UVT-610 hardening paint) is also provided (sprayed and formed) on the outer surface of the outer lens of the headlight.

[0011] Another object of the present invention is to provide an automotive headlight equipped with the above-mentioned outer lens of a headlight with anti-running down and anti-fogging functions.

[0012] The third objective of the present invention is to provide a preparation method for the above-mentioned headlight outer lens with anti-sag and anti-fog functions, which mainly includes the following steps: (a) molding the blank of the headlight outer lens and performing pretreatment on it; (b) fixing the blank of the headlight outer lens in an anti-fog spraying tooling fixture, spraying anti-fog paint on the inner surface of the headlight outer lens blank, and simultaneously forming an anti-fog coating area and a blank area. When manufacturing a car headlight equipped with the above-mentioned headlight outer lens with anti-sag and anti-fog functions, only need to install the headlight outer lens prepared in step (b) onto the car headlight assembly and seal it well.

[0013] Further, the pretreatment in step (a) includes operations such as removing the sprue and flash of the blank, cleaning the inner and outer surfaces of the blank, and heat treatment to remove stress.

[0014] Furthermore, the temperature for heat treatment to remove stress is 100 - 140 °C, and the heat preservation time is 20 - 30 min.

[0015] Further, at least one hardened coating is prepared on the outer surface of the headlight outer lens by means of flow coating before or after step (b).

[0016] Further, the anti-fog spraying tooling fixture includes a fixture body and a cavity. The cavity is matched with the shape of the headlight outer lens. A baffle is arranged to extend outward at a position near the top of the inner surface of the headlight outer lens in the cavity, which is used to form a blank area when spraying anti-fog paint. After the headlight outer lens is placed in the cavity, the baffle just blocks the blank area. When the spraying robot sprays anti-fog paint according to the specified path, only a specific area (anti-fog coating area) is sprayed, and the anti-fog paint is not sprayed on the area prone to sag (blank area), thus taking into account both the anti-fog and anti-sag functions of the inner surface of the outer lens.

[0017] Further, the number of cavities on the anti-fog spraying tooling fixture is at least one, and two or more are more helpful to improve the fixture efficiency.

[0018] Compared with the prior art, the present invention has the following beneficial effects: It changes the traditional prejudice that anti-fog of the headlight outer lens must be fully sprayed, analyzes and clarifies the root cause of the sag problem, provides a simple and low-cost semi-spraying solution, without the need to design complex dehumidification structures such as ventilation, drying, and heating as in the past, without the need to spend a lot of effort in researching and developing and improving anti-fog coating materials, and basically retains the existing processes and equipment. Therefore, the transformation and upgrading investment is small, and the newly developed headlight products have never had the sag problem. Brief Description of the Drawings

[0019] Figure 1 It is a physical photo of a headlight with sag;

[0020] Figure 2 It is a schematic structural diagram of the headlight outer lens with anti-sag and anti-fog functions provided by the present invention;

[0021] Figure 3 Schematic structural diagram of the spraying tooling fixture used in the present invention;

[0022] Figure 4 Comparison diagram of the water mist experiment results of automotive headlights equipped with the headlight outer lens with anti - sagging and anti - fog functions of the present invention and ordinary headlight outer lenses. Specific embodiments

[0023] To enable those of ordinary skill in the art to fully understand the technical solutions and beneficial effects of the present invention, the following further explanations are made in conjunction with specific embodiments.

[0024] As Figure 1 shown, after being used for a period of time, automotive headlights on the market often show a teardrop - shaped sagging phenomenon (the white dotted lines within the white circle are sags, located inside the headlight). The applicant's R & D team collected a large number of defective headlight parts with sagging problems. Through laboratory simulation and disassembly and inspection of the defective parts, it was found that the starting position of the sagging is concentrated in the upper - middle part of the inner surface of the outer lens. In addition, the component analysis of the anti - fog paint shows that it contains a large amount of hydrophilic materials and can dissolve in water under certain circumstances.

[0025] Combining the above facts, analysis and demonstration, it can be known that during the use process, the anti - fog coating on the inner wall of the headlight outer lens continuously absorbs moisture to play an anti - fog role. Due to design and usage environment reasons, the distribution of water vapor content inside the lamp cavity is not uniform, and the water vapor content is higher closer to the upper part of the lamp cavity. This is because after the light source is lit, it generates high temperature, causing the temperature inside the lamp cavity to rise. The water vapor becomes less dense after being heated and gradually accumulates in the upper part of the headlight, resulting in this position exceeding the saturation threshold of the anti - fog coating (at this time, the anti - fog coatings in other parts are not yet saturated). The anti - fog paint is dissolved by the water vapor to form a mixed liquid and flows downward to form sagging.

[0026] After figuring out the reason, only a simple modification is needed on the basis of the original process. When spraying the anti - fog paint, ensure that a certain area in the upper part of the inner surface of the outer lens is not sprayed (semi - spraying, as Figure 2 shown), thus completely solving the industry problem. The reason behind setting the blank area and the position selection of the blank area are a major highlight and innovation of the present invention. Before this, no one has done similar research, and no one is clear about the above mechanism.

[0027] The manufacturing method of the above - mentioned headlight outer lens with anti - sagging and anti - fog functions is as follows: First, form the blank of the headlight outer lens, and then heat - treat the blank in an environment of about 125 °C for 15 minutes to fully eliminate the internal stress in the blank. Take out the blank, remove the sprue and flash at the edge, and then clean its inner and outer surfaces to prepare for painting.

[0028] Fix several blanks of the headlight outer lens in the anti - fog spraying tooling fixture (asFigure 3 As shown in the figure, the baffle exactly covers the entire upper edge of the inner surface of the outer lens of the vehicle lamp (corresponding to the blank area on the outer lens of the vehicle lamp). Then, an anti-fog paint is sprayed on the inner surface of the blank body of the outer lens of the vehicle lamp, and at the same time, an anti-fog coating area and a blank area are formed. Finally, a hardening paint is sprayed on the outer surface of the blank body of the outer lens of the vehicle lamp to obtain a hardening protection layer.

[0029] To fully understand the actual use effect of the improved outer lens of the vehicle lamp obtained by the present invention, it is assembled together with a traditional outer lens of the vehicle lamp (with the same shape and the same anti-fog paint of the same material is fully sprayed on the inner surface) on the same model of automobile headlamp, and a double-chamber fogging experiment is carried out. At least 3 test samples are set in each group to enhance the reliability of the results. The specific test process is as follows:

[0030] a) Place the lamps in the environment of 23±4°C and 80%±5%RH at the installation position and let them stand for ≥24h respectively;

[0031] b) Then install the lamps at the installation position into the double-temperature box respectively, and strictly control the time from being taken out of the environment in a) to being installed to not exceed 5 minutes;

[0032] c) Heat up at a rate greater than 2°C / min to raise the ambient temperature of the lamp body (rear side) to 80±3°C, and control the humidity at 10%±5%RH; adjust the temperature of the lamp cover (front side) to 20±3°C and 75%±5%RH; at the same time, rain on the lamp cover (front side), and the rain parameters are: flow rate of 18L / min at a pressure of 3bar, water temperature of 15±3°C, and rain duration of 30 minutes. The high and low beams are lit throughout the process, and the other functions are lit according to the set conditions of the specific working logic of the lamp on the vehicle model. When there is function multiplexing, select the condition of the maximum power to light.

[0033] d) Take out the lamps and place them in the room temperature environment to stand, observe the appearance of the lamps, and record the time and degree of fog dissipation.

[0034] The results of the double-chamber fogging experiment are as Figure 4 shown. It can be seen from the figure that the automobile headlamp equipped with the improved outer lens of the vehicle lamp (semi-anti-fog) of the present invention does not show water mist during the whole test process, and there is no running and sagging phenomenon after the test is completed (left figure), and the appearance is still intact; while the inner surface of the automobile headlamp equipped with the traditional fully anti-fog outer lens of the vehicle lamp shows a very obvious running and sagging phenomenon, which has seriously affected the lighting effect and appearance of the headlamp (right figure). It can be determined from this that the semi-anti-fog outer lens of the vehicle lamp provided by the present invention has very obvious anti-fog and anti-running and sagging effects.

Claims

1. An external lens for a vehicle lamp with anti-sagging and anti-fogging functions, characterized in that an anti-fogging coating area sprayed with anti-fogging paint and a blank area not sprayed with anti-fogging paint are provided on the inner surface of the external lens of the vehicle lamp, and the blank area is in the shape of a slender strip and is located at the upper position of the inner surface of the external lens of the vehicle lamp.

2. The external lens for a vehicle lamp with anti-sagging and anti-fogging functions according to claim 1, characterized in that: the blank area is horizontally arranged along the top of the inner surface of the external lens of the vehicle lamp, or is inclined along the top contour of the inner surface of the external lens of the vehicle lamp.

3. The external lens for a vehicle lamp with anti-sagging and anti-fogging functions according to claim 2, characterized in that: the widths at both ends of the blank area are smaller than the width in the middle of the blank area.

4. The external lens for a vehicle lamp with anti-sagging and anti-fogging functions according to claim 1, characterized in that: a hardening coating is provided on the outer surface of the external lens of the vehicle lamp.

5. A vehicle lamp with anti-sagging and anti-fogging functions, characterized in that the external lens described in claim 1 is assembled on the vehicle lamp.

6. A preparation method for the external lens of a vehicle lamp with anti-sagging and anti-fogging functions as claimed in claim 1, characterized in that it includes the following steps: (a) Molding a blank body of the external lens of the vehicle lamp and performing pre-treatment on it; (b) Fixing the blank body of the external lens of the vehicle lamp in an anti-fogging spraying tooling fixture, spraying anti-fogging paint on the inner surface of the blank body of the external lens of the vehicle lamp, and simultaneously forming an anti-fogging coating area and a blank area.

7. The preparation method according to claim 6, characterized in that: the pre-treatment in step (a) includes removing the sprue and flash of the blank body, cleaning the inner and outer surfaces of the blank body, and heat treatment to remove stress.

8. The preparation method according to claim 7, characterized in that: the temperature for heat treatment to remove stress is 100 - 140 °C, and the heat preservation time is 20 - 30 min.

9. The preparation method according to claim 6, characterized in that: before or after step (b), a hardening coating is prepared on the outer surface of the external lens of the vehicle lamp by means of dip coating.

10. The preparation method according to claim 6, characterized in that: the anti-fogging spraying tooling fixture includes a fixture body and at least one cavity located on the fixture body, the cavity matches the shape of the external lens of the vehicle lamp, and a baffle is extended outward at a position on the cavity close to the top of the inner surface of the external lens of the vehicle lamp for forming a blank area on the inner surface of the external lens of the vehicle lamp when spraying anti-fogging paint.

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