According to its functions, automotive lighting system can be divided into lighting lamps and signal lamps. Lighting categories include: high beam, low beam, front fog lights, reversing lights and license plate lights. Signal categories include: brake lights, front and rear turn lights, rear fog lights, front and rear position lights, position lights, parking lights, side marker lights, and retro reflectors. Rear position lights, reversing lights (optional), brake lights, rear fog lights (optional), rear turn lights, and retro reflectors (optional) are combined together to be called rear combination lights. According to light source, rear combination lamp can be divided into: bulb, light pipe and light emitting diode (LED). Performance comparison of each light source is shown in Table 1. Rear combination lights can be divided into sheet metal sealing and self-sealing according to different sealing methods; according to different installation positions, they can be divided into wing lights and box lights or A lights and B lights.

 

According to different light sources, front combination lamps are generally divided into xenon lamps and halogen lamps. Generally, low beam lamp uses a halogen lamp or a xenon lamp, and high beam lamp uses a halogen lamp. Lighting effect can be seen in Figure 2. Compared with ordinary bulbs, xenon bulbs have following notable features:

 

a. Xenon bulbs have three times higher light intensity than ordinary halogen bulbs, but consume only two-thirds of energy;
b. Xenon bulb uses almost same light color as daylight, creating better visual conditions for driver. Xenon lamps make light range wider and lighter intensity, which greatly improves safety and comfort of driving;
c. Xenon bulb has a long life, reaching 3000h, and there is almost no need to replace bulb during entire vehicle life.
Xenon headlights must be equipped with headlight cleaning devices, height of headlights is automatically adjusted, which is a mandatory requirement by regulations. Disadvantage of xenon headlights is relatively high cost.

 

Main parts of front combination lamp are basically plastic parts, which are formed by injection molding. Combination of front combination light lens and housing-xenon lamp renderings. Halogen lamp renderings. Design guide for front combination lamps generally uses hot melt glue and cold glue. Table 1 shows comparison between two. At present, domestic suppliers mostly use hot-melt adhesive for bonding, cost is relatively low. Luminaire is arranged according to shape. If ineffective area not illuminated by light is relatively large, an anti-fog coating is generally added on inner surface of light distribution lens to reduce chance of fogging, but this will increase cost. Therefore, generally when doing styling design, try to reduce area of invalid area as much as possible.

 

 

Installation point layout and related cross-section
Installation point of luminaire should be based on position of center of gravity, shape and size. Generally, 1 positioning point and 2 to 4 installation points are evenly arranged to avoid excessive force on local installation points, otherwise installation bracket may be easily broken. After completing preliminary data, perform CAE analysis to understand vehicle modal analysis, frequency, natural frequency of lamp, avoid resonance, check whether installation strength meets requirements. Table 6 is a comparison of installation cross-sections of several models of AC, AD, and AF, their installation forms are basically same.

 

 

 

 

For headlight layout, it is recommended to avoid collision area as much as possible to improve pedestrian protection performance.

 

 

In arrangement of AC installation points, due to need of modeling, division and sheet metal structure, installation points cannot be arranged at position of dashed frame in Figure 12, resulting in excessive force on second installation point. In order to better control gap and surface difference, AC front combination lamp is equipped with adjusting nuts at second installation point, third installation point and auxiliary installation point, as shown in Figure 13. If sheet metal is manufactured and assembled with high precision, adjustment nut can be omitted to save cost.

 

Rear combination lamp is a lighting and signal lamp, usually including position lamps, brake lamps, reversing lamps, rear fog lamps, rear steering lamps and retro reflectors. Among them, reversing lamp, rear fog lamp and retro reflector may also be independent without being integrated in rear combination lamp. Specific functions of each function are as follows:
Rear turn signal lamp: a lamp used to indicate to other road users behind vehicle that vehicle will turn left or right;
Brake light: a light that indicates to other road users behind vehicle that vehicle is braking;
Rear fog lamp: A lamp that makes vehicle easier to see when viewed from rear of vehicle in heavy fog;
Reversing lights: lights that illuminate road behind vehicle and warn other road users that vehicle is or is about to reverse;
Rear position lights: viewed from rear of vehicle, lights on the surface and width of vehicle;
Retro reflector: A device that indicates presence of a vehicle to an observer near light source through reflected light irradiated by an external light source.
Introduction to typical structure, process and materials of rear combination lamp
Rear combination lamp is usually composed of an outer light distribution lens, a decorative frame, a housing, an inner light distribution lens, and a light source assembly. If you need to reduce costs, decorative frame and shell can be integrated. Typical structure of combined lamp after bulb light source and LED light source is shown in figure below.

 

 

External lens material (Lens): PMMA, low cost, high light transmittance of 90%-92%, excellent resistance to ultraviolet rays and atmospheric aging. Housing: Housing is mainly used for fixing and sealing. According to working temperature, ABS or PC/ABS is generally selected.
Decorative frame (bezel): If decorative frame is integrated wit reflector, select PC, PC-HT, if reflector is not integrated, you can directly use ABS. Inner lens: Since inner lens is usually very close to bulb and requires high heat resistance, high-temperature PC is generally selected. PC or PMMA can also be used when temperature is low. Limit temperature of each general material is shown in following table.

 

 

Rear combination lamp and sheet metal are usually connected, fixed by bolts and nuts. One end of bolt is fixed to rear combination lamp, the other end is fixed with sheet metal by a nut. Common type of nut is M5 or M6. Arrangement of installation points of rear combination lamp varies according to different shapes, and there are mainly following arrangements.

 

 

Development direction of rear combination lamp is lightweight, green and energy-saving, beautiful, intelligent and fast response speed.
6.1 Adaptive Rearlighting System (ARS), mainly by increasing indication area or brightness of each function, shortening response time, further improving driving safety, is divided into automatic recognition of environment brake position light , emergency brake lights, adaptive reversing lights, etc.