1. Outdoor lighting designers must consider the working environment of outdoor LED lamps.
Due to the complex working environment of led outdoor lighting fixtures, it is affected by natural conditions such as temperature, ultraviolet rays, humidity, rain in rainy days, sand and dust, and chemical gases. Over time, it will lead to serious problems of LED light decay. Therefore, outdoor lighting designers should consider the impact of these external environmental factors on LED outdoor lighting fixtures when designing.
2. Matters needing attention in the selection of heat dissipation materials for outdoor LED lamps.
The shell and the radiator are designed as a whole to solve the heating problem of the LED. This method is better. Generally, aluminum or aluminum alloy, copper or copper alloy, and other alloys with good thermal conductivity are used. Heat dissipation includes air convection heat dissipation, strong wind cooling heat dissipation and heat pipe heat dissipation. Jet cooling heat dissipation is also a kind of heat dissipation similar to heat pipe, but the structure is more complicated.
The choice of heat dissipation method has a direct impact on the cost of lamps and lanterns. It should be comprehensively considered and the best solution should be selected with the design product.
The design and selection of the lampshade is also very important. Currently, transparent plexiglass, PC materials, etc. are used. The traditional lampshade is a transparent glass product. What kind of material the lampshade is selected is related to the product grade positioning of the design. Generally speaking, the lampshade of outdoor lamps is best made of traditional glass, which is the best choice for making long-life, high-grade lamps. Lampshades made of transparent plastic, plexiglass and other materials are better for indoor lamps, but have a limited life when used outdoors. Due to factors such as outdoor sunlight, ultraviolet rays, sand and dust, chemical gases, and changes in temperature difference between day and night, the aging life of the lampshade is shortened, and secondly, the pollution is not easy to clean, which reduces the transparency of the lampshade and affects the light output.
3. Packaging technology of outdoor LED chips.
At present, most domestically produced LED lamps (mainly street lamps) are assembled with 1W LEDs in series and parallel. This method has higher thermal resistance than products with advanced packaging technology, and it is not easy to create high-quality lamps. Or use 30W, 50W or even larger modules for assembly to achieve the required power. The packaging materials of these LEDs are encapsulated with epoxy resin and silicone. The difference between the two is that epoxy resin encapsulation has poor temperature resistance and is easy to age over time. Silicone packaging has better temperature resistance, so you should pay attention to the selection when using it.
It is better to use a multi-chip package with a heat sink as a whole, or use an aluminum substrate multi-chip package and then connect it to the heat sink through a phase change material or heat-dissipating silicone grease. The thermal resistance of the product is higher than that of the product assembled with LED devices. At least one or two thermal resistances are more conducive to heat dissipation. For lamps using LED modules, the module substrate is generally a copper substrate. The connection between it and the external radiator should use a good phase change material or a good heat dissipation silicone grease to ensure that the heat on the copper substrate can be transferred to the external radiator in time. If it is not handled properly, it is easy to accumulate heat and cause the temperature of the module chip to rise too high, which affects the normal operation of the led chip.
4. Research on radiator design of outdoor LED lighting fixtures.
The radiator is a key part of the LED lamp. Its shape, volume, and heat dissipation surface area must be designed to be beneficial. The radiator is too small, and the working temperature of the LED lamp is too high, which affects the luminous efficiency and life. The radiator is too large. The consumption of materials will increase the cost and weight of the product, which will reduce the competitiveness of the product. Designing a proper LED light heat sink is crucial. The design of the radiator has the following parts:
A. Identify the power that LED lights need to dissipate.
B. Some parameters for designing heat sinks: specific heat of metal, thermal conductivity of metal, chip thermal resistance, heat sink thermal resistance, ambient air thermal resistance, etc.
C. Determine the type of cooling to be used (natural convection cooling, strong wind cooling, heat pipe cooling, and other cooling methods.) From the cost comparison: natural convection cooling is the lowest cost, strong wind cooling is medium, heat pipe cooling is more expensive, and jet cooling is the highest cost.
D. Determine the maximum permitted working temperature of LED lamps (ambient temperature plus permitted temperature rise of lamps).
E. Calculate the volume and heat dissipation area of the radiator. And determine the shape of the radiator.
F. Combine the radiator and LED lamp into a complete lamp, and power on for more than eight hours. Check the temperature of the lamp at a room temperature of 39°C--40°C to see if it meets the heat dissipation requirements to check whether the calculation is correct. conditions, the parameters need to be recalculated and adjusted.
G. The seal between the radiator and the lampshade should be waterproof and dustproof, and an anti-aging rubber pad or silicon rubber pad should be placed between the lampshade and the radiator, and fastened with stainless steel bolts to be sealed against water and dust. Then refer to the latest technical specifications for outdoor lighting lamps promulgated by our country, as well as urban road lighting design standards, this is the most basic knowledge that outdoor lighting designers must have.
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