JPH06239268A - Hood for automobile - Google Patents

Abstract

PURPOSE:To enable the peak value of an impact reaction force to be controlled within a fixed limit range, and further enable deformation stroke to be reduced. CONSTITUTION:An automobile hood panel is provided with an energy absorption mechanism 41a for a rigid part 37 laid below the panel, and mass materials 45a and 45b not having rigidity but mass, are provided within the prescribed range for the part 37 in accordance with the curvature of the panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile hood.

[0002]

2. Description of the Related Art Conventionally, for example, there is a hood shown in FIG. 15 described in Japanese Utility Model Laid-Open No. 61-67265 or a hood shown in FIG. 16 described in Japanese Utility Model Laid-Open No. 60-28557.

A hood 1 shown in FIG. 15 has an outer panel 3
The inner panel 5 and the inner panel 5 constitute a hood panel 7, and the inner panel 5 is attached to the outer panel 3 with an adhesive 8.

When an impact force F acts on the hood 1 from the outside, the force F is absorbed by the deformation of the hood panel 7. However, if the impact force F is large, there is a risk of causing secondary interference with the rigid body component 9 such as the engine below the hood 1, and the inner panel 5 is, for example, a semicircular shape in order to absorb the impact force at the time of secondary interference. Has a convex portion 5a. Therefore, the rigid part 9
The impact force can be absorbed by the crushing of the convex portion 5a at the time of the secondary interference with.

In the hood 1 shown in FIG. 16, a panel 11 is further provided so as to efficiently absorb the impact at the time of secondary interference with the rigid component 9. Note that FIG.
6, the convex portion 5a has a trapezoidal shape.

[0006]

[Invention for Solving the Problems] FIGS. 15 and 1
Since any of the hoods 1 of 6 absorbs the impact mainly by the deformation of the hood panel 7, great care must be taken in setting the shape of the inner panel 5 and the like. In particular, considering the secondary interference with the rigid part 9, it is preferable that the peak value of the reaction force at the time of shock absorption is within a certain limit and the deformation stroke of the hood panel 7 is small. Was accompanied by difficulties.

Therefore, an object of the present invention is to provide an automobile hood capable of reducing the deformation stroke at a peak value within a certain limit regardless of the shape setting of the hood panel.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 provides a hood panel of an automobile with an energy absorbing mechanism for a rigid part arranged below the hood panel, Within a predetermined range for the rigid part of the hood panel according to the curvature of the panel,
The feature is that a mass material having no mass but having rigidity is provided.

The invention according to claim 2 is the hood according to claim 1, wherein the mass material having no mass but having rigidity is the effective mass of the hood panel and the peak value of the impact reaction force at the time of energy absorption. And the relationship between the effective mass and the energy absorption of the peak wave of the impact reaction force, the required amount is determined.

[0010]

According to the first aspect of the present invention, when an impact force is input to the hood panel, the impact force is first absorbed by the effective mass of the hood panel and the energy absorbing mechanism, and the remaining energy after that is the energy. It is further absorbed by the absorption mechanism. Therefore, energy can be absorbed efficiently.

According to the second aspect of the invention, the required amount of the mass material is related to the effective mass of the hood panel and the peak value of the impact reaction force at the time of energy absorption, and the effective mass and the impact reaction force. It can be determined from the relationship with the energy absorption of the peak wave, and an efficient structure can be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a partial cross section of a vehicle hood 31 according to an embodiment of the present invention, and FIG. 2 shows an exploded perspective view of a vehicle body. FIG. 1 is taken along the line II of FIG. As shown in FIGS. 1 and 2, the hood 31 covers the engine room 35 of the vehicle body 33 in an openable and closable manner. In the engine room 35, a rigid body part 3 such as an engine is provided below the hood 31.
7 are arranged.

The hood 31 comprises an outer panel 39 and an inner panel 41 to form a hood panel 42, and the inner panel 41 is attached to the outer panel 39 by an adhesive 43.

The inner panel 41 has a semi-circular convex portion 4
1a and functions as an energy absorbing mechanism for a rigid part 37 such as an engine arranged below the hood 31.

Further, the outer panel 39 is made of a material having a mass but no rigidity, such as mel sheet or α.
Mass materials 45a and 45b such as gel are provided.

The mass members 45a and 45b are provided on both sides of the inner panel 41, and each inner edge portion 45c covers the flange portion 41b of the inner panel 41. This mass material 4
5a and 45b are provided larger than the rigid part 37 arranged below the hood 31 by a predetermined range L.
This range L is set according to the radius of curvature of the hood 31, as shown in FIG. That is, as the locality radius becomes smaller, the range of influence of the secondary collision on the rigid body part 37 becomes wider, so that L is increased in accordance with the decrease in the locality radius. Since the hood 31 is usually close to a flat plate, the range L in this case is about 240 mm.

The required amount of the mass members 45a and 45b is
It is calculated from the relationship between the effective mass of the hood panel 42 and the peak value of the impact reaction force, and the relationship between the effective mass of the hood panel 42 and the energy absorption of the impact peak wave.

Here, in order to explain the determination of the required amount of the mass members 45a and 45b, an impact force F is applied to the conventional hood 1 from the outside.
Consider the behavior when is applied.

As shown in FIG. 4, when the impact force F acts on the hood 1 from the direction of the arrow, immediately after the action, as shown in FIG. 5, the entire hood 1 is not deformed and the force F acts. The outer panel 3 is locally deformed at the position. Further, the inner panel 5 may be locally deformed depending on the operating position. The panel rigidity when this local deformation occurs is called "local rigidity". If this local deformation step is passed, as shown in FIG. 6, the entire hood 1 bends and interferes with the rigid component 9 such as the engine.

In this case, the relationship between the deceleration of the deformation due to the force F and the displacement (stroke) is shown in FIG.

In FIG. 7, the peak waveform of the impact reaction force that first appears as shown by the solid line is due to the local rigidity and the effective mass of the hood 1, and the subsequent characteristics are the overall rigidity of the hood 1 and the inner panel. This is due to the deformation characteristic of No. 5.

The area surrounded by the deceleration-displacement curve shown by the solid line in FIG. 7 should basically be equivalent to the initial kinetic energy when the impact force F acts. Considering the secondary interference with the rigid body component 9, it is preferable that the hood has the smallest stroke within a certain area while the peak value of the impact reaction force is within the limit. It should be able to absorb. In other words, the shape of the deceleration-displacement curve is preferably such that it has a characteristic that first shows a high value within a certain limit and then gradually decreases.

Therefore, when designing the hood, the initial impact peak waveform in FIG. 7 is increased as much as possible until it approaches a certain limit value, and thereafter the reaction force generated when the inner panel 5 and the rigid part 9 interfere with each other is suppressed. It is necessary to devise it. Further, if more energy is absorbed in the first impact peak waveform, less energy is absorbed by the inner panel 5 and the like that follow, in other words, the amount of displacement can be reduced. Therefore, in FIG. 7, for example, when the solid line shows the characteristics shown in FIGS. 4 to 6, it is desirable to have the characteristics shown by the broken lines.

More specifically, as shown in FIG. 8, the hood 1 shown in FIG. 1 is a dynamic model composed of a mass and a spring based on an effective mass 21, a local rigidity 23, an overall rigidity of the hood and an inner panel deformation characteristic 25. Can be replaced with

Then, how the phenomenon when the impact force F acts on the element of the hood will be considered as follows.

That is, when the local rigidity 23 and effective mass 21 of the hood are changed with respect to a certain standard hood structure,
The shock peak value of the waveform that occurs first is as follows.

G _pm = α _m · G _po (1) G _pk = α _k · G _po (2) Here, G _po : impact peak value in the reference hood, G
_pm : Impact peak value when the effective mass is changed, G
_pk : _Shows the impact peak value when the local rigidity is changed.

Note that α _m is the impact peak value increase ratio for the reference hood with respect to the effective mass increase ratio, and is obtained from FIG. Further, α _k is the impact peak value increase ratio for the reference hood with respect to the local rigidity increase ratio, and can be obtained from FIG.

From FIGS. 9 and 10, it is understood that the influences of the changes in the local rigidity 23 and the effective mass 21 on the impact peak value are almost the same.

On the other hand, the energy absorption characteristics are as follows.

E _pm = β _m · E _p (3) E _pk = β _k · G _p (4) where E _p : energy absorption at the first impact peak waveform in the reference hood, E _pm : effective mass _{Shows the} energy absorption amount in the first impact peak waveform when _V is changed, and E _pk is the energy absorption amount in the first impact peak waveform when the local stiffness is changed.

Note that β _m is the rate of change in the amount of absorbed energy with respect to the effective mass increase rate, and can be obtained from FIG. Further, β _k is an energy absorption amount ratio with respect to a local rigidity increase ratio, and can be obtained from FIG.

It can be seen from FIGS. 11 and 12 that the effect of changing the effective mass is overwhelmingly large in terms of energy absorption.

Next, the initial kinetic energy when the impact force F acts is expressed as follows.

E _oo = 1/2 · (M · V ² ) ... (5) Here, E _oo : initial kinetic energy, M: mass, V: velocity.

Therefore, in order to finally absorb the impact force F, the remaining energy after being absorbed by the effective mass from the initial kinetic energy E _oo , that is, (E _oo -E _pm ) and the local rigidity are used. Remaining energy after being absorbed:
That is, it is necessary to obtain (E _oo −E _pk ) by absorbing energy due to the deformation of the inner panel. On the other hand, since the deformation characteristics of the inner panel have been conventionally known, the displacement of the inner panel can be known from this relationship, and the force F
It is possible to know the final displacement of the part where was operated.

Therefore, according to this embodiment, the hood 31
In designing, the effective mass of the hood 31 should be the mass material 45.
The value G _pm of the first impact peak waveform generated immediately after the force F acts after being adjusted by a and 45b is determined by the relationship shown in FIG. 9, and the energy amounts E _pm and E absorbed by the impact peak waveform are determined. _pk is obtained from the relationship shown in FIGS.

Next, the energy absorption amounts E _pm and E
_{From pk,} the remaining energy of the original kinetic energy E _oo (E
_oo −E _pm ) and (E _oo −E _pk ).

Next, the energy (E _oo −E _pm ),
The structure of the inner panel 41 is designed so that (E _oo −E _pk ) is absorbed by the inner panel 41.

Therefore, the design procedure of the hood 31 is simplified and the structure can be made efficient.

According to the hood 31 of this embodiment, when the impact force F acts on the hood 31, the impact force F immediately after the action is sufficiently absorbed by the impact peak waveform having a large area of the hood 31, and thereafter The remaining energy is absorbed by the deformation of the inner panel 41.

Therefore, the impact peak value can be controlled within a certain limit, and the deformation stroke of the hood 31 can be further reduced.

FIG. 13 shows another embodiment of the present invention. The same components as those in FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

In this embodiment, the mass member 47 is also provided on the inner panel 41 mounting portion, and the inner panel 4 is attached to this mass member 47.
In this embodiment, the same effects as those of the above-mentioned embodiment are obtained. In addition, in this embodiment, the mass material 47 can be integrally molded, which facilitates manufacturing and parts management.

FIG. 14 shows a modification of the embodiment shown in FIG.

In this embodiment, the mass material 49 such as mel sheet is used.
The rigid parts 3 of the hood 31 do not have a uniform thickness of a and 49b.
The portion deviated from 7 is formed into a thick wall 51. However, the mass material 49 in the portion separated from the rigid body part 37
The total mass of a and 49b is formed in the same manner as when they are uniformly provided.

Also in this embodiment, the same operation and effect as those of the above-mentioned embodiment can be obtained. Further, the range L can be reduced with an equivalent mass, which is effective when it is desired to reduce L in relation to other parts.

The mel sheet is preferably provided with a uniform thickness in order to reduce the wall thickness, but it may be considered that a hole is provided in a part of the mel sheet. In this case, it is necessary to arrange a mass corresponding to the holes in the periphery. At this time, the mass material may have ridges and valleys, but this is not a problem.

Further, by mixing iron powder into the mass material to increase the density, it is possible to reduce the thickness of the mass material.

[0051]

As is apparent from the above description, according to the invention of claim 1, the peak value of the first impact reaction force when the impact force acts can be controlled to be within a certain limit. The final displacement amount can be reduced. Therefore, energy can be efficiently absorbed with a small deformation of the hood panel. Further, since the deformation of the hood panel is reduced, it is possible to set an appropriate height at a position closer to the rigid part under the hood panel.

According to the second aspect of the present invention, the procedure for designing the hood can be simplified, and an efficient structure for absorbing energy can be surely set.

[Brief description of drawings]

1 relates to a hood according to an embodiment of the present invention, and FIG.
2 is a cross-sectional view taken along the line I-I of FIG.

FIG. 2 is an exploded perspective view of a vehicle body provided with a hood according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a radius of curvature of a vehicle body panel and a range in which a mass contributes to an impact.

FIG. 4 is an explanatory diagram of a deformation mode of the hood.

FIG. 5 is an explanatory diagram of a deformation mode of the hood.

FIG. 6 is an explanatory diagram of a deformation mode of the hood.

FIG. 7 is a diagram showing displacement characteristics.

FIG. 8 is a mechanical model diagram of a hood.

FIG. 9 is a diagram showing a relationship between an effective mass and an increase rate of a peak value of impact reaction force.

FIG. 10 is a diagram showing a relationship between local rigidity and an increase rate of a peak value of impact reaction force.

FIG. 11 is a diagram showing a relationship between effective mass and energy absorption of shock peak waves.

FIG. 12 is a diagram showing a relationship between local rigidity and energy absorption of a shock peak wave.

FIG. 13 is a sectional view of another embodiment of the present invention.

FIG. 14 is a sectional view of a modified example of the present invention.

FIG. 15 is a sectional view of a hood according to a conventional example.

FIG. 16 is a sectional view of a hood according to another conventional example.

[Explanation of symbols]

31 Hood 37 Rigid Parts 39 Outer Panel 41a Convex Part (Energy Absorption Mechanism) 45a, 45b, 47a, 47b, 49a, 49b Mass Material

Claims (2)

[Claims] 1. A hood panel of an automobile is provided with an energy absorbing mechanism for a rigid body part disposed below the hood panel, and the rigidity is set within a predetermined range of the hood panel relative to the rigid body part according to a curvature of the hood panel. A hood for an automobile, characterized in that a mass material having a mass is provided. 2. The automobile hood according to claim 1, wherein the mass material having no mass but having rigidity has a relationship between an effective mass of the hood panel and a peak value of an impact reaction force at the time of energy absorption, and A required amount is determined from the relationship between the effective mass and the energy absorption of the peak wave of the impact reaction force.