JP4281744B2 - Bonnet structure for vehicles - Google Patents

Description

  The present invention relates to an automobile bonnet structure mainly composed of an outer panel and an inner panel.

  The vehicle bonnet is lightweight and highly rigid, and has a small injury value (an index indicating the damage of the pedestrian in the collision. Details will be described later) at the time of collision with the pedestrian, and the amount of entry (the bonnet caused by the collision). The amount of deformation in the direction of the engine room is also desired to be small.

As a bonnet structure of an automobile mainly composed of an outer panel and an inner panel, for example, as shown in Patent Document 1 and Patent Document 2 below, a plurality of dimples are formed on the inner panel to make it lightweight and highly rigid. Are known.
JP 2000-168622 A US Pat. No. 5,244,745

  However, in the above conventional structure, since only a plurality of dimples are provided on the inner panel, it is difficult to partially adjust the balance between the injury value and the approach amount, and it is difficult to obtain a sufficient degree of design freedom. There was a problem.

  In view of such circumstances, the present invention provides a bonnet structure that realizes light weight, high rigidity, and low injury value, and that can be easily optimally designed so that the injury value and the amount of penetration are ideally balanced. To do.

According to a first aspect of the present invention, in a bonnet arranged to cover an engine room of a vehicle and having an outer panel and an inner panel, the inner panel substantially has a recess recessed from the inner panel toward the back surface of the outer panel. dimples frustoconical formed a plurality, wherein the periphery of said dimples of the inner panel together when the plurality of through holes are provided outside the dimples, the imperforate area provided with no pre SL through hole, the inner panel The vehicle bonnet structure is provided with a predetermined width along an axis of a frame portion extending from the front portion to the rear portion of the vehicle.

  According to a second aspect of the present invention, in the bonnet structure for a vehicle according to the first aspect, the plurality of dimples and the plurality of through holes are spaced apart from each other in a region where at least three of them are distributed. Are substantially equal intervals, the interval between adjacent through holes is approximately equal, and the interval between adjacent dimples and through holes is approximately equal.

  According to a third aspect of the present invention, in the vehicle bonnet structure according to the first or second aspect, a plurality of sets of the through holes adjacent to each other in the vehicle width direction are arranged in a row in the vehicle width direction. .

  According to the first aspect of the present invention, since the inner panel is provided with dimples and a plurality of through holes are provided around the inner panel, the bonnet has a light and high rigidity structure. There is an effect that there is no large bias in the injury value.

  Further, the through holes can be optimally designed by adjusting the hole diameter and arrangement so that the injury value and the amount of penetration are in an ideal balance.

  According to the invention of claim 2, since the dimples and the through holes are substantially evenly distributed, the rigidity of the bonnet is made more uniform, and the effect of preventing locally large obstacle values depending on the collision site is enhanced. I can do it.

  According to the third aspect of the present invention, since the portions having through holes whose rigidity is lower than that of the surroundings are arranged in the vehicle width direction, the bonnet folding start point at the time of the front collision is easily formed.

  In the following description, the center means the center in the left-right direction, and the center portion means the center portion in the front-rear, left-right direction in the bonnet body.

Before describing embodiments of the present invention, reference embodiments showing the basic configuration of the present invention will be described. First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of the bonnet 1. The outer panel 2 is an outer plate of the bonnet 1 and becomes a part of the exterior of the vehicle.

  FIG. 2 is a bottom view of the bonnet 1.

  The bonnet 1 mainly includes an outer panel 2 and an inner panel 3, and the inner panel 3 is joined to the outer panel 2 with an adhesive or the like. The outer panel 2 and the inner panel 3 are maintained at a substantially constant distance, but the inner panel front portion 31 which is the front side of the inner panel 3 has a bulge inside the vehicle, and the distance between the outer panel 2 and the outer panel 2 is increased. Yes.

  The inner panel 3 is provided with a plurality of dimples 6 (21 locations in FIG. 2). The dimple 6 is a substantially frustoconical (mortar-shaped) depression.

  Furthermore, the inner panel 3 is provided with a plurality of through holes 7 (34 locations in FIG. 2).

  As shown in FIG. 2, the dimples 6 and the through holes 7 are regularly arranged. The dimple 6 is provided at each vertex of an equilateral triangle with one side a1 within the arrangement region. And the through-hole 7 is provided in the gravity center position of the equilateral triangle of the one side a1. Accordingly, the distance between each dimple 6 and the through hole 7 and the distance between adjacent through holes 7 are both a2, and the relationship between a1 and a2 is a1 = √3 × a2.

  Moreover, the 1st flame | frame part 4 is provided along the left-right and back periphery of the bonnet 1. As shown in FIG. The first frame portion 4 has a trapezoidal cross-sectional frame shape formed by the outer panel 2 and the inner panel 3 bent in a U shape. The front end of the first frame part 4 is connected to the inner panel front part 31.

  In the side part of the first frame part 4, the outer panel 2 and the inner panel 3 are bonded intermittently. The bonded portion has a completely closed cross section, but the non-bonded portion has a substantially closed cross section with a slight gap.

  3 is a QQ cross-sectional view of FIG. 2, and FIG. 4 is an RR cross-sectional view of FIG. FIG. 5 is a cutaway perspective view showing a part of the outer panel and the inner panel.

  As shown in FIGS. 3 to 5, a portion corresponding to the bottom of the mortar of each dimple 6 is joined to the outer panel 2 by an adhesive 8.

  Due to the structure as described above, the bonnet 1 has the highest rigidity in the vicinity of the outer peripheral edge due to the first frame portion 4, and the rigidity is relatively low in the central portion and the central portion. Further, locally, the portion where the dimple 6 is present has higher rigidity than the surroundings, and the portion where the through-hole 7 is present has lower rigidity than the surroundings.

  When the bonnet 1 collides with a pedestrian, especially when the collision part of the pedestrian is local, such as the head, even if the hood has a relatively low rigidity at the center of the bonnet, the dimple 6 is relatively rigid. There is also a possibility that a load is applied intensively at a high point. Even in such a case, since the load is distributed and transmitted along the dimple shape (the frustoconical slope), the amount of shock absorption is large. That is, the dimple 6 has an effect of alleviating the local rigidity unevenness of the bonnet 1 and avoiding that the injury value is greatly different only by slightly different collision positions.

  In addition to reducing the weight of the through-hole 7, by appropriately adjusting the hole diameter and the number of holes, it is possible to adjust the rigidity and formulate a compatible point between the injury value and the approach amount.

  Since the bonnet 1 has the dimples 6 and the through-holes 7 uniformly arranged at equal intervals as described above, the bonnet 1 has high uniformity in injury value and intrusion amount.

At the time of the front collision , a folding start point is formed at a place where the through hole 7 is present. That is, locations where there are dimples having rigidity higher than the surroundings and locations where through holes having rigidity lower than the surroundings are arranged alternately, and two through holes 7 are arranged side by side. Thus, the folding start point is easily formed.

Next, a second reference embodiment of the present invention will be described with reference to FIG.

Note that, in the second reference embodiment, the same parts as those in the first reference embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

FIG. 6 (a) is a bottom view of the bonnet 1 as the second reference form, and FIG. 6 (b) is a cross-sectional view taken along the line SS of FIG. 6 (b).

The second reference form is different from the first reference form only in that the second frame portion 5 is provided, and the other structures are the same.

  The second frame portion 5 is a frame that extends rearward from the inner panel front portion 31 at the center of the bonnet 1 and has a rib shape with a width L1 that protrudes from the inner panel 3 toward the outer panel 2. A gap P is provided between the second frame portion 5 and the outer panel 2.

  The central part of the bonnet is a part where the bending rigidity tends to be small, but by providing the second frame part 5, the rigidity of the bonnet central part can be supplemented and the rigidity of the entire bonnet can be made more uniform. .

  Further, due to the gap P between the second frame portion 5 and the outer panel 2, the bonnet 1 in this portion is deformed by the outer panel 2 at an early stage after the collision, and the rigidity is increased.

Next, based on each reference form mentioned above , FIG. 7 demonstrates 1st embodiment of this invention.

Figure 7 is a bottom view of the hood 1 which is a first embodiment. The first embodiment is different from the second reference embodiment only in that it has a non-hole region 9 in which the through hole 7 is not provided in a predetermined range indicated by oblique lines around the second frame portion, and the other structure is the same.

  The non-porous region 9 is set with a width L <b> 2 symmetrically along the axis of the second frame portion 5. In the non-hole region 9, the through hole 7 is not provided even in the arrangement pattern of the through hole 7.

Therefore, in the first embodiment, has become more high rigidity of the bonnet central portion as compared to the second reference embodiment, the rigidity of the hood center portion also in the second reference embodiment in the design phase is insufficient In this case, by adopting this structure, the rigidity can be supplemented and the rigidity of the entire bonnet can be made more uniform.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a bottom view of the bonnet 1 according to the second embodiment.

  The second frame portion 51 has a front width L3, a rear width L4, and L4 is set to be larger than L3.

The second embodiment is different from the first embodiment only in the shape of the second frame portion 51, and the other structures are the same.

  As described above, the bending rigidity at the center of the bonnet tends to be small. However, since the bonnet has a shape in which the width dimension is widened to the rear side, the bending rigidity at the rear of the center is particularly likely to be small.

For this reason, in 2nd embodiment, the rigidity of the bonnet center part rear side is made especially high compared with what made the 2nd frame part equal width. Accordingly, when the rigidity at the rear of the bonnet center is insufficient even in the first embodiment at the design stage, the rigidity is compensated by adopting this structure, and the rigidity of the entire bonnet is made more uniform. be able to.

The bonnets of the first and second reference embodiments and the first and second embodiments as described above exhibit specific injury values and entry amount characteristics. The theory and simulation results are shown below.

  The injury value (HIC) is defined by the following equation (Equation 1).

  In (Equation 1), assuming that the head of a pedestrian collides with the bonnet, a is the head combined acceleration (m / s2) at the time of collision, t is time (ms), and t1 and t2 are in the collision process. It represents an arbitrary time (ms), t2> t1> 0 and t2−t1 ≦ 15 ms.

  That is, among all time segments of 15 ms or less in the collision process, the time segment in which the value in the braces on the right side of (Equation 1) is the maximum is (t1, t2), and the value in the curly brackets at that time Is defined as the injury value HIC.

  The smaller the injury value HIC, the smaller the damage to pedestrians.

  On the other hand, when the injury value HIC is reduced, the amount of deformation of the hood generally increases and the amount of entry into the vehicle tends to increase. Therefore, it is necessary to formulate a structure that reduces the intrusion amount while reducing the injury value HIC.

  When a certain injury value HIC is fixed, the combined head acceleration G (t) that minimizes the amount of approach is theoretically obtained by the following equation (Equation 2).

  (Equation 2) is an expression obtained by placing the values in the braces of (Equation 1) always equal so that the head synthesized acceleration G (t) is inversely proportional to the 0.4th power of time t. When set, it indicates that the amount of entry is minimized.

  The above indicates that, in the bonnet 1, increasing the head combined acceleration in the initial stage of the collision and decreasing the combined head acceleration in the late stage of the collision result in the minimum injury value and the amount of entry.

  Accordingly, a structure that generates such acceleration while balancing the rigidity is desirable, and it is more desirable that there is no particularly large or small rigidity around the area and that the deformation amount is not biased.

  By doing so, it is possible to prevent the injury value from changing greatly even if the collision position is changed a little.

  In addition, the degree of freedom in design can be further increased if the amount of approach can be adjusted due to the engine room layout.

  FIG. 9 shows simulation results of injury values and entry amounts.

  FIG. 9 shows the simulation results of the injury value and the approach amount at points A and B shown in FIG. 9A. FIG. 9B shows point A and FIG. 9C shows point B. It is a result.

In each graph, the vertical axis indicates the injury value HIC, and the horizontal axis indicates the entry amount (mm). The plotted types-1, 2, 3, and 4 correspond to the first reference form , the second reference form , the first embodiment, and the second embodiment , respectively.

  In the graph of the point A, the injury value and the approach amount are decreased in type-2 as compared with type-1, and the effect of the second frame portion 5 is exhibited. In type-3 and 4, the injury value is further decreased and the effect is shown, while the approach amount is slightly increased.

  In the graph of point B, the injury value decreases in the order of type-2, 3, and 4 in comparison with type-1, and the effect appears, while the amount of entry is also increased.

  Such a simulation can be carried out at other points, and the final employment structure can be formulated while taking into account the injury value and the allowable limit of the approach amount.

  In types-2, 3, and 4, since there are setting elements for the width dimensions L1, L2, L3, and L4 of the second frame portions 5 and 51, the design freedom is higher.

  In addition to the above-described embodiment, the following embodiments (a) to (e) are also possible.

  (A) The arrangement of the dimples 6 may be a polygon arrangement other than an equilateral triangle arrangement, another regular arrangement, or a random arrangement.

  (B) The arrangement of the through holes 7 may be other regular arrangements or random arrangements.

  (C) A structure in which the features of the above-described embodiments are selectively combined is also possible.

  (D) The first frame portion 4 can be joined to the outer panel 2 entirely as necessary.

  (E) The second frame portions 5 and 51 can be joined to the outer panel 2 partially or entirely as required.

It is a perspective view of the bonnet concerning the first reference form of the present invention. It is a bottom view of the bonnet concerning the first reference form of the present invention. It is QQ sectional drawing of FIG. It is RR sectional drawing of FIG. It is a notch perspective view which shows a part of outer panel and inner panel concerning the first reference form of this invention. It is a bottom view of the bonnet concerning the 2nd reference form of the present invention. It is a bottom view of the bonnet concerning a first embodiment of the present invention. It is a bottom view of the bonnet concerning 2nd embodiment of this invention. It is a simulation result of the injury value and the approach amount according to the first and second reference embodiments and the first and second embodiments of the present invention.

Explanation of symbols

1 Bonnet 2 Outer panel 3 Inner panel 4 First frame part 5, 51 Second frame part (frame part)
6 Dimple 7 Through-hole 8 Adhesive 9 Non-porous area 31 Front of inner panel

Claims (3)

In a bonnet disposed so as to cover an engine room of a vehicle and having an outer panel and an inner panel, the inner panel has a plurality of substantially frustoconical dimples recessed from the inner panel toward the back surface of the outer panel. is formed, said around the dimples of the inner panel together when the plurality of through holes are provided outside the dimples, the imperforate area provided with no pre SL through hole, extending to the rear from the front of the inner panel A bonnet structure for a vehicle, which is provided with a predetermined width along an axis of the frame portion .
  In the region where the plurality of dimples and the plurality of through holes are distributed in at least three or more locations, the distance between the adjacent dimples and the dimple is substantially equal, and the distance between the adjacent through holes and the through hole is substantially equal. The bonnet structure for a vehicle according to claim 1, wherein the bonnet structure for vehicles is equidistant, and the distance between adjacent dimples and through holes is substantially equidistant.   The bonnet structure for a vehicle according to claim 1 or 2, wherein a plurality of sets of the through holes adjacent to each other in the vehicle width direction are arranged in a row in the vehicle width direction.