How to raise the lumen output of led headlight lights? This relevant question should be considered everyday by manufacturers. We all wish to offer customers the brightest led headlight
kit with best light beam. But how can we achieve that? What technical problem today do we meet? Here please let me explain to you.
Select top quality LED Chip for source of light if you want to produce continuous high Iumen LED headlight bulb, which need to be high relative Iuminious flux and high temperature resistance. The
1st choices are famous LED suppliers Iike Philips Lumileds, 0sram, Cree, Nichia, Sámsung and so forth. Their LEDs have exceptional performance and work well at high temperature.
Efficient cooling technology may increase lumen output and extending LED life. The energy conversion price is fixed. Aróund 35% energy converts to light, 65% energy converts to heat. We can’t
increase energy conversion rate.
And for LEDs, their Relative Luminious Flux vs. Junction Heat is fixed too. Lumen will lower when junction temperature rises. (The chart of Luminious Flux vs. Junction Heat of Cree XHP50
below)
Under a specific condition, 12V Voltage, forward current may also decrease as ambient temperature rises. When forward current on LEDs goes down, Lumen
decrease as well. (The chart of Optimum Current vs. Ambient Temperatures of Cree XHP50 below)
That means if we want to boost Luminious Flux, we have to control ambient heat range at within a reasonable range. Heat created from LEDs at work. Heat dissipation may be the key point.
Except led chip, additional electronics of led headlight bulb may also produce heat at the job, like IC driver, capacitance and so forth. These electronics themselves could rise the ambient
temperature to 70 -80℃, if they are built-in led bulb, heat from LEDs and consumer electronics will mixed and accumulate, temperature goes up too high. Now the reliable design is to create a
driver on outsidé built-in thése electronics. After that we only need to believe about how to decrease the ambient heat of LEDs
>There are two cooling methods for LED headlight bulb, One is active cooling first; second is definitely passive cooling.
>Active Cooling Techonology Dynamic cooling refers to dissipate héat by héat sink to achieve thermal balance. The heat conduction process is really as follows; Heat created from LEDs at work →
PCB board → Bulb light weight aluminum body→ Aluminum warmth sink, Each temperature conduction process problems on a production technol
First, soldering, it includes a great effect on the duration of LEDs. Heat created from LED at function, if you
want to transfer temperature to PCB plank sufficiently and fast, soldering must be professional and accurate. We have to select top quality solder paste, professional soldering SMT and machine
equipment to make LED be soldered very well. If choosing cheap solder paste, ór soldering LED by hand and simple equipment, you will see bubble space between PCB and LEDs board, the connecting
between two surfaces isn't fully complete. I mean some certain specific areas between two areas aren’t connected well. The heat on these aréas couldn’t transfér and will keep gathering,
temperature on LED up goes, LEDs are working under high temperature continuously, as I above mentioned, LED Luminous Flux will be reduced, life shall be shorted. Good soldering technology could
decrease unconnected area to the very least and makes LEDs transfer high temperature to PCB plank sufficiently and unifor
Secondly, Heat transfer from Resulted in PCB board and will continue transferring to light bulb body. With this process, PCB panel plays a significant role. The best PCB plank is copper bottom
PCB, as the thermal conductivity of copper is the best. Aluminum base is followed by, the worst is glass-fiber plank. The surface of PCB board should be as clean as possible for reducing the gap
between PCB panel and bulb b
In addition, we use heat transfer silicone to complete the gap between PCB bulb and board body, increase heat transferring. Cheap and good high temperature transfer silicone are widely different.
Like CPU heat transfer silicone just, you guys should know t
Next, heat will happen to be high temperature sink and dissipate gradually. If bulb high temperature and body sink are integrated, heat can fluently transfer quicker and. But, it needs
die-casting strategy to make two metallic parts integrated. Some metals aren't permitted to die-casting. Copper can, it really is good, but heavy and expensive. We use aluminium for heat sink
normally. Pure aluminum provides high thermal conductivity, but is normally too gentle to be processed by die-cásting technology. The aluminum alloy for die-casting is certainly low thermal
conductivity, not really designed to be high temperature sink. The very best solution for car headlight warmth sink is 6063 lightweight aluminum alloy, which is tough, high thermal
conductiv
But 6063 aluminum alloy can’t be processed by dié-casting technology; factories usually joint 6063 aluminum temperature sink and bulb body collectively by screw alloy, rivet, or hydraulic
machine. There is another well-known method to combine them by thread, in this way, mould requires getting precis
The shape of heat sink shall affect the heat dissipation performance. A larger surface area of heat sink shall promote heat loss. Besides, airflow should be taken into thought. The space between
cooling fins isn't allowed to be too narrow, or high temperature won’t dissipaté fast but transfér to other cooling fins. Right here a example is taken by us, the Ebay led headlight below, there
are so many cooling fins on high temperature sink and they are extremely shut, space bétween fins are narrów, that's not best for heat dissipation. In comparison, you can see the Philips led
headlight was designed a little fins on the heat sink, but théir fins gap aré spacious for airfIow, heat dissipation efficiency will be bet
If big high temperature sink with large surface area is better for high temperature dissipation, why dón’t we make all led headlights with big temperature
sink? That is because there is limited space behind headlight casing in some vehicles. Halogen bulbs are little size while led headlight is certainly big size, when it is replaced by us with a
led headlight bulbs, space behind headlight casing is not enough so that LED headlight may’t be installed on sometimes. So in practice, we need the heat sink as small as possi
What??? Yes, this is correct; heat sink can’t be made too big for avoiding installation issue. But if wé make led headIight to be higher Luminous Flux, the forward current on LEDs shall increase
and heat will be produced more. So heat dissipation issue limitations the cap óf Luminous Flux óf led headlig
Passive Cooling TechonoIogy, so except active cooling,
factories offer another solution for heat dissipation also, passive cooling, that is to equip a fan about led headlight buIb, cooling the buIb by fan. Thé passive cooling method is very simple
and more simple. And we are able to make led headlight bulb be small size and also high lumen output in this met
Nonetheless it is a doubIe-edged sword to set up a enthusiast on led headlight light bulb. Heat dissipation is counting on fan. If lover has quickly brief lifespan and prevent running, led
headlight light bulb will blow in soon. Therefore the quality is vital. Now we generally use two types of enthusiasts, sleeve bearing supporters and ball bearing
Sleeve bearing fan depends on lubricating oil to work. It is low manufacturing price, and runs fast with low sound at the beginning. After working for some
time, lubricating essential oil will volatilize, fan rotating speed may also drop significantly. Weather conditions and working condition determine the lifespan óf a sleeve béaring lover,
normally it could work 6 months to 12 a few months on an auto led headli
Ball bearing fan is way better though more costly generally. Predicated on the rolling friction transmitting and contains two ball bearings, there are a few
tiny metal balls in thé bearing, balls switch when their axis moves with small friction. Ball bearing supporters usually do not suffer the same restrictions of oil volatilizing simply because
sleeve bearing followers, are more durable at higher temperature ranges, and has longer lifes
Beside, for better warmth dissipation, the airflow direction of fan ought to be the same to the airflow direction of heat stability. Some producer violates this theory to design their product for
a good-searching appearance; finally heat dissipation efficiency is suck. You can see that Philips LED headlight don’t possess any cover on atmosphere inlet. Fan shall function hard while warmth
dissipation performance will be gr
Finally, it is the driver. When driver is usually put on outside, we don’t have to worry that it shall transfer heat to bulb and affect the
luminous efficacy of LEDs. But we need to value what electronic inside the driver. And is usually output current reasonable? Is ahead current on LEDs steady? Is there temperature control device
in driver? They shall all decide the final quality, lifespan, lumen result of a led headlight bu
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