CN110154974A - Automotive hoods for improved pedestrian safety - Google Patents

Abstract

The invention relates to the technical field of automobile structures, in particular to an automobile engine cover for improving the safety of pedestrians; it includes an inner panel and an outer panel, the thickness of the outer panel is 0.34-0.45mm, and the thickness of the inner panel is 0.25-0.35mm; The aluminum honeycomb-EPP foam composite core material is filled between the inner panel and the outer panel, and the aluminum honeycomb-EPP foam composite core material includes the honeycomb aluminum core and the EPP foam filled in part of the honeycomb aluminum core; the honeycomb cell of the honeycomb aluminum core The cross-section of the element is a regular hexagon, the side length is 2.5-6mm, and the wall thickness is 0.05-0.07mm; the density of the EPP foam is 20-60kg/ ^m3 ; compared with the traditional engine cover, the engine cover of the present invention has more Good cushioning performance and cushioning energy absorption can provide better protection for pedestrians in the event of a collision; in addition, the engine cover of the invention is lighter in weight and has obvious energy-saving effects.

Description

Automotive hoods for improved pedestrian safety

technical field

The invention relates to the technical field of automobile structures, in particular to an automobile engine cover for improving the safety of pedestrians.

Background technique

In recent years, my country's automobile industry has achieved leapfrog development. As a pillar industry of the national economy, the automobile industry has become increasingly prominent in promoting the economy. According to the data released by the National Bureau of Statistics in January 2019, as of the end of 2018, the number of cars in my country increased by 22.85 million compared with the previous year, an increase of 10.51%, reaching 240 million. However, the development of the automobile industry has also brought a series of problems to the society, such as safety problems, air pollution and energy shortage, among which the traffic safety problem is particularly prominent.

According to the statistics of the World Health Organization (WHO), the number of deaths in road traffic accidents in the world is about 1.2 million every year, of which 46% are vulnerable groups, namely: pedestrians, bicycle riders or users of two-wheeled motor vehicles. In other countries, this proportion is even as high as 80%. The number of road traffic accident deaths in my country ranks among the highest in the world. According to the statistics released by the Traffic Management Bureau of the Ministry of Public Security, the number of road traffic accident deaths in China was about 100,000 per year from 2001 to 2015, and then decreased year by year. The number of people has remained at around 60,000. In 2018 alone, there were 213,000 traffic accidents in my country, resulting in 63,000 deaths and 226,000 injuries. Traffic accidents have caused great harm to people. Pedestrian safety is a severe and prominent problem that road traffic safety must face now and in the future.

The head injury caused by the collision between the head of the pedestrian and the hood of the car is the deadliest form of injury in human-vehicle collision accidents. According to statistics, the death rate of head traffic injuries is as high as 68%. Therefore, in human-vehicle collision accidents, Reducing the degree of pedestrian injury and improving the performance of pedestrian protection has become a hot issue in the research of automotive passive safety. Improving the structure of the front end of the car, the arrangement of parts under the hood, and the characteristics of the hood material can all improve its pedestrian head protection performance.

Figure 1 shows a traditional engine cover, which mainly includes an inner panel 100, an outer panel 101 and a reinforced panel 102. The material of the outer panel 101 is Baosteel cold-rolled strengthened steel plate B170P1 with a thickness of 0.7mm; the material of the inner panel 100 is cold-rolled The steel DC04 has a thickness of 0.6 mm; the reinforcement plate 102 is made of cold-rolled steel DC041 with a thickness of 1.5 mm. Its quality is heavy and its rigidity is strong, but its cushioning and energy absorption performance is poor, and the degree of protection for pedestrians is not enough.

The ideal requirements for a car hood are: good cushioning and energy-absorbing performance, light weight and appropriate strength (too much strength has poor cushioning performance, and the head is prone to secondary collisions if the strength is too small). Therefore, it is necessary to carry out further research and development on the automobile engine cover.

Contents of the invention

In order to solve the above-mentioned problems existing in the traditional engine cover, the present invention provides an automobile engine cover for improving the safety of pedestrians.

In order to achieve the above functions, the technical solution provided by the invention is:

An automobile engine cover for improving pedestrian safety, comprising an inner panel and an outer panel, the thickness of the outer panel is 0.34-0.45mm, and the thickness of the inner panel is 0.25-0.35mm;

An aluminum honeycomb-EPP foam composite core material is filled between the inner panel and the outer panel, and the aluminum honeycomb-EPP foam composite core material includes a honeycomb aluminum core and EPP foam filled in part of the honeycomb aluminum core;

The cross-section of the honeycomb cells of the honeycomb aluminum core is regular hexagon, the side length is 2.5-6 mm, and the wall thickness is 0.05-0.07 mm; the density of the EPP foam is 20-60 kg/m ³ .

Preferably, a plurality of communicating holes are opened on the side walls of the honeycomb cells.

Preferably, in each row of honeycomb cells, two continuous honeycomb cells not filled with EPP foam are arranged between every two honeycomb cells filled with EPP foam, and between two adjacent rows of honeycomb cells Any two honeycomb cells filled with EPP foam are not adjacent.

Preferably, two continuous honeycomb cells filled with EPP foam are arranged between every two honeycomb cells not filled with EPP foam, and any two honeycomb cells not filled with EPP foam between adjacent two rows of honeycomb cells Cells are not adjacent.

Preferably, the density of the EPP foam is 40kg/m ³ .

Preferably, the honeycomb cells of the aluminum honeycomb core have a side length of 3 mm and a wall thickness of 0.06 mm.

Preferably, the aluminum honeycomb-EPP foam composite core material has a thickness of 20 mm.

The beneficial effects of the present invention are:

1. The collision deformation area and displacement of the engine cover filled with composite core material are larger than those of the traditional engine cover, but its stiffness is smaller than that of the original engine and the peak load is also reduced, and the impact duration is prolonged, indicating that the buffer of the new engine cover Better performance than conventional hoods.

2. For the engine hood of the present invention, the pedestrian head injury HIC has decreased by 13.5% to 51.8%, the acceleration peak value has decreased by 9.7% to 39.2%, the maximum intrusion of the pedestrian head has little change, and no two collisions have occurred at all collision points. The automobile engine cover of the present invention has a better buffering and energy-absorbing effect.

3. Compared with the traditional structure engine cover, the local rigidity of the automobile engine cover of the present invention is reduced by 23.6%, the overall rigidity is reduced by 7.86%, the bending and torsional rigidity is increased by 6.25%, the mass is reduced by 3.25kg, and the weight reduction is 23.8% .

Description of drawings

Fig. 1 is the structural representation of traditional car engine cover;

Fig. 2 is a structural representation of the present invention;

Fig. 3 is the structure schematic diagram of class A composite core material;

Fig. 4 is the structural representation of B type composite core material;

Fig. 5 is the front view of honeycomb unit;

Fig. 6 is a schematic diagram of each collision point of the engine cover;

Fig. 7 is a comparison chart of the HIC values of two kinds of hoods at each collision point.

Detailed ways

Below in conjunction with accompanying drawing 1 to accompanying drawing 7, the present invention will be further elaborated:

A kind of automobile engine cover for improving pedestrian safety as shown in Fig. The honeycomb-EPP foam composite core material 3 includes a honeycomb aluminum core 31 and EPP foam 32 filled in part of the honeycomb cells 311 . When the thickness of the outer plate 1 is 0.34-0.45 mm and the thickness of the inner plate 2 is 0.25-0.35 mm, the cross-section of the honeycomb cell 311 of the honeycomb aluminum core 31 is a regular hexagon with a side length of 2.5-6 mm and a wall thickness of 0.05 mm. ~0.07mm, when the density of EPP foam 32 is 20 ~ 60kg/m ³ , the engine cover of the present invention is light in weight, energy absorption and strength are moderate, and various performance indicators are better.

In order to make the EPP foam 32 tightly connected with the honeycomb cells 311 after foaming, as shown in Figure 5, a number of communicating holes 3111 are opened on the side walls of the honeycomb cells 311, and the diameter of the through holes 3111 is generally 0.25-0.5 mm. In the process of producing the aluminum honeycomb-EPP foam composite core material 3 like this, when the EPP foam 32 is foaming, a part of the EPP foam 32 will stretch into the through hole when foaming, so that the EPP foam 32 and the honeycomb cell unit 311 are closely connected. connect.

As shown in Figure 3, it is a kind of honeycomb-EPP foam 32 composite core material (hereinafter referred to as A class composite core material), in the A class composite core material, every two honeycomb cells 311 filled with EPP foam 32 are arranged There are two continuous honeycomb cells 311 not filled with EPP foam 32 , and any two honeycomb cells 311 filled with EPP foam 32 are not adjacent between two adjacent rows of honeycomb cells 311 .

As shown in Figure 4 is another kind of honeycomb-EPP foam 32 composite core material (hereinafter referred to as B class composite core material), between every two honeycomb cells 311 not filled with EPP foam 32 in the B class composite core material Two consecutive honeycomb cells 311 filled with EPP foam 32 are provided, and any two honeycomb cells 311 not filled with EPP foam 32 are not adjacent between two adjacent rows of honeycomb cells 311 .

Table 1 shows that the side length of the honeycomb cell unit 311 of the honeycomb aluminum core 31 is 3mm, the wall thickness is 0.06mm, and the density of the filled EPP foam 32 is 40kg/m ³ A-type composite core material and B-type composite core material Comparison of peak force and energy absorption rate with Type C composite core materials. Wherein, the composite core material of type C means that all the honeycomb cells 311 in the small honeycomb units constituting the composite core material are filled with EPP foam 32 .

It can be seen from the above table that the mechanical properties of the filled composite core material are better than those of the unfilled core material, and the mechanical properties of the unfilled core material are too poor to be directly applied to the engine cover; There is little difference in the mechanical properties of the materials, and the mass specific energy absorption value of the A-type composite core material is the largest. That is to say, when the mechanical properties are close to and absorb the same energy, the quality of the A-type composite core material is the lightest, and the quality of the B-type composite core material is the second. These two filling methods are better than fully filled or unfilled core materials. Among them Class A composite core material is the most ideal filling type.

The technical effect that the present invention obtains is described below with several main performances of the automobile engine cover of the present invention and the traditional automobile engine cover. The thickness is 0.3mm, filled with A-type composite core material, and the filling thickness is 20mm.

(1), HIC value:

At present, HIC (Head Injury Criterion) is generally used as the evaluation standard of pedestrian head injury in the world, and its value is determined by the acceleration generated when the head collides and its duration.

The HIC value in the regulations uses 1000 as the critical value of head injury, and it is believed that an HIC exceeding 1000 will cause fatal injury to pedestrians.

The process of the experiment is carried out in accordance with the relevant regulations of Euro-NCAP. Since the engine hood has a left-right symmetrical structure, in order to avoid repeated tests, this paper selects the left half of the engine hood as the collision area. The selection of the final collision point is shown in Figure 6. Select 4 test points in the collision area of the adult headform and 8 test points in the collision area of the child's headform: the collision points of the adult headform are named A1, A2, ... A4; The mold collision points are named C1, C2, ... C8.

Figure 7 shows the HIC values of two kinds of hoods at each collision point. The HIC value of the traditional engine cover is generally high. Among the 12 collision points, the HIC value of only 4 points is lower than 1000, and the HIC value of 6 points exceeds 2000, and the highest even reaches 4770. protection is very disadvantageous. Compared with the traditional engine cover, the HIC value of each collision point of the engine cover of the present invention is significantly reduced (13.5%-51.8%), and the area below the HIC value of 1000 is increased from the original 4 points to 8 points. Although the HIC values of the remaining 4 points are still higher than 1000, compared with the traditional engine cover, there is still a large drop.

(two), mechanical properties:

The design of the hood should not only consider pedestrian protection but also ensure that the structure has sufficient static stiffness. The static stiffness of the hood mainly includes local stiffness, bending and torsional stiffness, and overall stiffness. An ideal hood should have a small local stiffness to improve the pedestrian safety protection performance of the hood, and it should have a large bending and torsional stiffness and overall stiffness. Rigidity to improve its resistance to deformation.

Table 2 is a comparison table of the results of the static stiffness of the traditional engine cover and the engine cover of the present invention.

Table 2:

As can be seen from Table 2, compared with the traditional structure engine cover, the local rigidity of the engine cover of the present invention has a large reduction (23.6%), while the bending and torsional rigidity is slightly improved (6.25%). The hood is slightly lowered (7.86%) than the conventional hood, which works well overall.

(3) Lightweight effect:

The mass of the traditional engine cover shown in Fig. 1 is 13.63kg, the mass of the engine cover of the present invention is 10.38kg, and the quality of the engine cover of the present invention has been reduced by 23.8%.

To sum up, it can be seen that the pedestrian protection performance and weight reduction effect of the automobile engine cover of the present invention are obvious.

The above-described embodiments are only preferred examples of the present invention, and are not intended to limit the scope of the present invention, so all equivalent changes or modifications made according to the structure, features and principles described in the patent scope of the present invention should be Included in the patent application scope of the present invention.

Claims (7)

1. a kind of for improving the automotive hood of pedestrian safety, including inner panel and outside plate, it is characterised in that: the outside plate With a thickness of 0.34~0.45mm, the inner panel with a thickness of 0.25~0.35mm；

Aluminum honeycomb-EPP foam composite core material is filled between the inner panel and the outside plate, the aluminum honeycomb-EPP foam is compound Core material includes Aluminum Honeycomb Cores and the EPP foam that is filled in the Aluminum Honeycomb Cores of part；

The cross section of the honeycomb cell element of the Aluminum Honeycomb Cores is in regular hexagon, and side length is 2.5~6mm, 0.05~0.07mm of wall thickness； The density of the EPP foam is 20~60kg/m³。

2. as described in claim 1 for improving the automotive hood of pedestrian safety, it is characterised in that: the honeycomb born of the same parents Several intercommunicating pores are offered on the side wall of member.

3. as described in claim 1 for improving the automotive hood of pedestrian safety, it is characterised in that: in every a line bee In nest cell element, every two is filled with the bee that there are two continuous without filling EPP foam of setting between the honeycomb cell element of EPP foam Nest cell element, and honeycomb cell element of any two filled with EPP foam is non-conterminous between two adjacent row honeycomb cell elements.

4. as described in claim 1 for improving the automotive hood of pedestrian safety, it is characterised in that: every two does not have Fill the honeycomb cell element of continuous filling EPP foam there are two settings between the honeycomb cell element of EPP foam, and two adjacent row bees Between nest cell element any two do not fill EPP foam honeycomb cell element it is non-conterminous.

5. the automotive hood for being used to improve pedestrian safety as described in Claims 1 to 4 any one, feature exist In: the density of the EPP foam is 40kg/m³。

6. the automotive hood for being used to improve pedestrian safety as described in Claims 1 to 4 any one, feature exist In: the side length of the honeycomb cell element of the Aluminum Honeycomb Cores is 3mm, wall thickness 0.06mm.

7. the automotive hood for being used to improve pedestrian safety as described in Claims 1 to 4 any one, feature exist In: the aluminum honeycomb-EPP foam composite core material is with a thickness of 20mm.