Design of car engine cover
As one of the most important modern transportation vehicles, automobiles are playing an increasingly important role in human life. People have higher and higher requirements for the safety of automobiles. Airbags, safety air curtains, seat belts, ABS, and other equipment are increasing. The more it appears on domestically-produced cars, the more research on pedestrian collision protection has not received equal attention. Compared with the year-on-year decrease in the number of occupant injuries and deaths in the car, the situation of pedestrian injuries and deaths outside the car has not been improved, so car safety protection is considered. At the same time as the driver and passengers in the car, the protection of pedestrians on the road should also be considered. In the event of an accident, the injury value should be reduced to the minimum, and the two sides should be protected from injury as much as possible to improve the pedestrian protection characteristics of the vehicle mainly follow the following two principles: 1. Reduce the relative collision speed between the various parts of the pedestrian and the vehicle after a collision by optimizing the shape of the front part of the vehicle. 2. Reduce the stiffness of the collision area and improve the energy absorption characteristics of the collision area. ●Pass the collision test (including actual vehicle test, model) Module test and computer simulation, etc.) to simulate and reproduce collision accidents, study the rules of collision accidents, and explore ways to avoid accidents or reduce accident losses.
When designing a car, the structural layout of the hair cover system is one of the main factors to consider pedestrian protection.
1. The function and requirements of the hair cover system
When the hair cover is opened, it satisfies the opening angle of the general layout, and keeps a certain distance from the surrounding parts during the opening process; it has good heat insulation to prevent the high temperature in the engine compartment from being transmitted to the driver; the appearance is beautiful and the manufacturing process is good, easy to wash and convenient Install and cooperate with other components; meet pedestrian protection requirements.
2. The composition of the hair cover system
The hair cover system generally consists of the inner and outer panels of the hair cover, the left and right hinges of the hair cover, and the reinforcement plate of the matching parts of the hair cover. Hair cover accessories generally consist of a hair cover locking mechanism, a hair cover buffer mechanism, a hair cover sound insulation and sealing, and a wiper nozzle.
3. Hair cover structure
The hair cover support is supported by gas springs and support rods. When the support rod is used, manpower is required to lift the hair cover. In order to avoid a laborious operation, weight reduction should be considered when designing the inner panel. The outer panel is affected by the shape.
The impact cannot be changed. Try to open holes in the inner plate as much as possible. While opening the alkali and heavy holes, it is necessary to consider the anti-concave property of the hair cover and improve the rigidity of the hair cover + usually arrange the shock isolation glue on the front end of the hair cover and the inner plate ●
In the case of function and performance, it is necessary to consider that the inner panel of the hair cover should not be installed with sound insulation pads.
The aesthetics of the inner panel of the cover. The shape of the inner plate of the hair cover varies greatly according to the aesthetics of each person.
The inner panel of the hair cover usually has energy-absorbing ribs, mainly including single energy-absorbing ribs, double energy-absorbing ribs, and broken line suction.
The main function of energy-absorbing ribs is that the hair cover assembly bends at the energy-absorbing ribs when the vehicle collides.
To absorb energy ●Prevent the hair cover from moving backward and invade the cockpit, causing damage to the occupant's ●Energy-absorbing tendons--General
The arrangement position of the hair cover is between 0.4L-0.7L (L is the total length of the hair cover).
Four. Hair cover hinge type
According to the structure and shape, the hair cover hinge can be divided into four-link type, gooseneck type, and scissors type. At present, the hair cover hinge is commonly used in a scissor-type, mainly because of the cost. Some models use a four-link type due to the interference between the hair cover opening and the peripheral parts, which changes the movement track of the hair cover opening to avoid interference. The design and layout of the hinges need to consider collision protection for pedestrians, and the hinges and buffer blocks should be arranged outside the pedestrian protection area as much as possible.
V. Pedestrian protection area determination
The emergence of the Pedestrian Protection Law plays a decisive role in the protection of pedestrians, and it also poses new challenges to the design of the bumper of the car’s front cabin structure.
1. The front line setting of the collision area of the hair cover
Front end line A: Make a vertical line perpendicular to the ground from the front end of the car body, smooth the hair cover section line, and intercept the point from the ground to the hair cover section line with a length of 1000mm. The line connected by this point is the front end of the collision area. Of the line.
Front end line B: Make a line at an angle of 40 degrees with the ground. The line formed by the tangent point of this line and the car body's positive offset to X by 82.5 mm is the line at the front end of the collision area.
In contrast, the two front-end lines of the collision area A and B set above, select the one with the largest X direction
The line is to send Cover the front end of the collision area.
2. The side end line setting of the hair cover collision area
Do-a line at 45 degrees to the ground. The line formed by the tangent point of this line and the body is offset from the inside of the body by 82.5mm.
3. Setting the back end of the hair-cover collision zone
This line is determined by a line formed by a ball with a diameter of 165mm tangent to the front windshield glass, and then to the tangent point of the hair cover. This line is negatively offset to X by 82.5mm, which is the back End of the line.
4. Child and adult head collision area setting
Among the pedestrian injuries, the head and lower limbs are the most vulnerable, while the chest and abdomen are relatively less traumatic. Lower limb injuries mostly cause the disability of pedestrians. It does not directly lead to death, and the head causes a higher probability of pedestrian death. Therefore, the head collision area between children and adults is set: the child head protection area: the vertical line from the front end of the car body perpendicular to the ground to smooth the hair cover section line, and intercept the length from the ground to the hair cover section line The point is 1700mm. The line formed by this point is the last line of the child's head collision area. The area composed of this line, the front line, and the side end line is the child's head protection area.
Adult head protection area: make a vertical line from the front end of the car body to the ground, smooth the section line of the hair cover, intercept the point from the ground to the surface line of the hair cover with a length of 2100mm, connect this point into a line, and compare and select The smallest X direction between this line and the back end line is the final line of the adult head collision area. The area formed by this line and the back end line and the side end line of the child head protection area is the adult head protection area.
Pedestrian protection regulations aim to protect the heads of adults and children from colliding with the hair cover in the event of a car accident. Therefore, when designing the hair cover, it is necessary to consider that strong parts such as hair cover locks cannot be arranged in the collision area. Child collision area: the distance between the powertrain and other parts is greater than 70mm; the adult head collision area: the distance between the powertrain and other parts is greater than 80mm'
6. Conclusion
The amount of deformation of the car body during a collision depends on the material used, the strength and angle of the collision, and the speed at the time of the collision is a key factor in the form and severity of the injury. Therefore, the design of the hair cover must be considered. The material used can absorb the energy of the head in a controlled mode to reduce head injury indicators. Most cars use a thinner steel plate to absorb energy in the event of a collision. At the same time, it is necessary to strengthen the pedestrian protection device, such as the engine cover. The mechanical system can convert the kinetic energy that hits the pedestrian into the energy to lift the engine cover, which forms an energy-absorbing area between the pedestrian, the engine cover, and the parts in the engine room. The deformation of the engine cover reduces the impact on the head and shoulders of pedestrians.
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