KR20110029855A - Bumper assembly for vehicle - Google Patents

Abstract

PURPOSE: A bumper assembly for a vehicle using foaming aluminum is provided to enhance the durability of a vehicle since the housing and the inner foam of the buffer box are formed from an aluminum material so that galvanic corrosion is prevented. CONSTITUTION: A bumper assembly for a vehicle using foaming aluminum comprises a bumper beam(30) and a buffer box(50). The bumper beam is installed on at least one of the front and the rear of the vehicle. The buffer box is installed between the bumper beam and the side member(25) of the vehicle. The bumper beam comprises a housing and inner foam. The housing is formed from an aluminum alloy material. The inner foam is inserted into the inner space of the housing. The inner foam is formed from a foaming aluminum material with a density of 0.2~0.5g / cm^3.

Description

Bumper assembly for vehicle using foamed aluminum

The present invention relates to a bumper, and more particularly, to a bumper assembly for a vehicle using foamed aluminum, which is composed of a housing and an absorbent foam made of aluminum, which can effectively absorb a shock applied to an automobile.

In general, a bumper for a vehicle is to elastically deform at a low speed collision of the vehicle to prevent physical damage of the vehicle. In other words, the vehicle bumper absorbs the shock generated when the vehicle collides with another vehicle or the stationary body, and serves to enhance the safety of the occupant.

This general bumper structure is shown in FIG. As shown in the drawing, the stay 3 is coupled to the front side member 1 extending forward from the frame of the vehicle. The stay 3 is for connecting the bumper beam 5 and the front side member 1 to be described later.

A bumper beam 5 is coupled to the front side member 1 with the stay 3 therebetween. The bumper beams 5 are provided in the vehicle width direction in front and rear of the vehicle, respectively, and are composed of two bumper rails.

The absorber 7 is again connected to the bumper beam 5. The absorber 7 is a portion that substantially absorbs shock, and as shown in the figure, extends in the vehicle width direction similarly to the bumper. The absorber 7 and the bumper beam 5 are wrapped by a bumper cover 9.

Meanwhile, between the two bumper rails, a reinforcing panel, which is a reinforcing member, is welded to reinforce the rigidity of the bumper beam 5.

According to such a bumper structure, when an impact is applied from the outside of the vehicle, the absorber 7 is compressed and absorbs some of the collision energy, and the remaining layer stone energy which the absorber 7 does not absorb is absorbed by the bumper beams behind the back. 5) and through the stay (3) is dispersed and absorbed into the vehicle body.

However, the prior art as described above has the following problems.

In the case of the bumper structure, the impact energy is uniformly absorbed when the impact energy is distributed from the front, such as a pendulum impact test or a fixed wall collision test, and is relatively stable. However, when the impact energy is concentrated locally, the impact force is dispersed. This difficulty has a problem that the degree of breakage is severe.

In order to solve this problem, the thickness of the bumper beam 5 or the stay 3 may be increased or an additional reinforcing member may be further provided. However, this increases the manufacturing cost and increases the weight of the bumper structure and the vehicle as a whole, thereby improving fuel efficiency. Will fall.

Therefore, in order to stabilize and reduce the weight of the bumper structure, a crash box for absorbing impact energy has been recently developed, the contents of which are disclosed in Application No. 10-1995-0058982. The crash box is mainly made of heterogeneous materials, for example ferrous metals and non-ferrous metals to improve the energy absorption rate.

However, Galvanic Corrosion is easily generated between dissimilar metals, so durability is low, and in the case of ferrous metals, the weight of the bumper structure is limited due to its high specific gravity, and its relatively high specific gravity does not sufficiently absorb external shocks. There is this.

Accordingly, an object of the present invention is to provide a bumper assembly of a vehicle that can effectively absorb external shocks and at the same time reduce the weight of the vehicle in relation to the background art as described above.

Another object of the present invention is to provide a buffer box of a bumper assembly of a vehicle, each consisting of a housing made of aluminum and an absorbent foam.

Still another object of the present invention is to optimize the impact energy absorption rate of the shock absorbing box by appropriately setting the density of the absorbent internal foam forming the shock absorbing box.

According to a feature of the present invention for achieving the object as described above, the present invention is provided between the bumper beam and at least one of the front or rear of the vehicle, and the bumper beam and the side member of the vehicle is transmitted from the outside The shock absorbing box is configured to include a shock absorbing box, and the shock absorbing box is configured to include a housing made of an aluminum material in which an accommodating space is formed, and an absorbent internal foam inserted into the accommodating space and formed of a foamed aluminum material. .

The density of the absorbent foam is 0.2g / cm ³ ~ 0.5g / cm ³ to be

The shape of the cross section of the housing is formed in regular polygon or circle.

A partition wall is formed in the housing along the longitudinal direction of the storage space of the housing, and the absorbent foam is inserted into each storage space partitioned by the partition wall.

At least one end of both ends of the housing is provided with a flange, and the flange is fastened to the bumper beam or the side member by a fastener or coupled by soldering.

According to the bumper assembly for a vehicle using foamed aluminum according to the present invention, the following effects can be expected.

In the present invention, since the shock absorbing box made of aluminum constituting the bumper assembly effectively absorbs external shocks, damage to the vehicle body can be minimized, and at the same time, the weight of the vehicle can be reduced due to the characteristics of the material.

Further, in the present invention, since the buffer box of the bumper assembly of the vehicle is composed of a housing made of an aluminum material and an absorbent internal foam, respectively, galvanic corrosion can be prevented and the durability of the vehicle can be expected to be improved.

In addition, in the present invention, the density of the absorbent internal foam constituting the shock absorbing box is set to 0.2 ~ 0.5g / cm ^{3 so} that the shock energy absorption rate of the shock absorbing box is greatly improved, so that the safety of the vehicle is improved, and only a separate shock absorbing box can be replaced. This makes the maintenance of the bumper assembly easier.

In addition, in the present invention, the bumper beam and the side member are connected by the buffer box without a separate stay, so that more effective shock absorption is possible and the number of parts is reduced. In addition, the variable due to the presence of the stay disappears in the impact absorption amount calculation. The advantage is that more sophisticated designs are possible.

Hereinafter, exemplary embodiments of a vehicle bumper assembly using foamed aluminum according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a perspective view showing a frame structure of a vehicle employing a preferred embodiment of a vehicle bumper assembly using foamed aluminum according to the present invention, FIG. 3 is a perspective view showing a configuration of an embodiment of the present invention, and FIG. The configuration of the shock absorbing box constituting the embodiment of the present invention is shown in perspective view, and FIG. 5 is a perspective view of the structure of the absorbent foam forming the embodiment of the present invention.

As shown in these figures, the bumper assembly for a vehicle using foamed aluminum is largely composed of a bumper beam 30, a side member 25, and a buffer box 50. The side members 25 constitute the front underbody 20 extending from the frame 10 of the vehicle, and are provided at both sides of the front end of the vehicle.

The bumper beam 30 extends in the width direction of the front underbody 20 and is formed in a bar shape as shown. In this embodiment, the front of the vehicle is described as an example, but the same may be applied to the rear structure.

A buffer box 50 is provided between the bumper beam 30 and the side member 25. The buffer box 50 serves to absorb and cushion an external shock applied to the bumper beam 30, and as shown, both edge portions between the bumper beam 30 and the side member 25. It is provided in pairs.

As shown in Figure 4, the buffer box 50 is composed of a housing 51 and the absorbent interior foam (60). The housing 51 forms an appearance and a skeleton of the shock absorbing box 50. An accommodation space is formed therein so that the absorbent internal foam 60 may be inserted therein.

The housing 51 is made of aluminum. The housing 51 has a relatively small volume and relatively low specific gravity (2.7) compared to the bumper beam 30 to reduce the overall weight of the bumper assembly.

In the present embodiment, the housing 51 is formed in a rectangular parallelepiped shape, but is not necessarily limited thereto. As shown in FIG. 7, the shape of the cross section may have various polygonal shapes including a regular octagon, and a circular shape may be possible. At this time, the housing 51 has a relatively large absorption energy to be described later when the cross-sectional shape is a regular polygon.

Although not shown, a partition wall may be provided in the storage space of the housing 51. The partition wall divides the storage space into two or more spaces, so that the two or more absorption built-in foams 60 are received, respectively.

The absorption built-in foam 60 is made of aluminum. More precisely, the absorbent internal foam 60 is a kind of porous aluminum that is made to form amorphous pores 65 by mixing a metal foaming agent with an aluminum material. In this case, since the absorption embedded foam 60 is made of the same aluminum material as the housing 51, galvanic corrosion is prevented, and the energy absorption rate of the absorption embedded foam 60 may be improved due to the pores 65.

Looking at the process of manufacturing the absorbent internal foam 60, the aluminum material and the metal foaming agent is mixed in a predetermined ratio and heated in a standardized form to a certain shape to solidify the foamed foam of the liquid, and then of the housing 51 It is cut into shape of storage space.

In this case, the liquid foamed foam is formed by mixing aluminum powder and foaming powder (SiC + TiH_2), which is a metal foaming agent, in a mixer at a ratio, and adding a thickener (Ca) in a heater to heat in a predetermined temperature range. .

Alternatively, the absorbent foam 60 may be manufactured through a compression and extrusion process by mixing an aluminum material and a metal foaming agent. In this case, after mixing the aluminum powder and the foaming powder (TiH_2) through a mixer, the compressor is Extruded through compression, and finally foamed through heat treatment.

Absorption built-in foam 60 prepared as described above is absorbed by the impact energy is transmitted through the bumper beam 30, the pores 65 is reduced while absorbing sufficient impact energy. In this case, the proportion of the pores 65 in the absorption built-in foam 60 becomes the most important variable for absorbing the impact energy, which will be described in detail below.

The housing 51 is provided with a flange 57. The flange 57 is for assembling the housing 51 to the bumper beam 30 or the side member 25 more easily, and may be provided at at least one of both ends of the housing 51.

At this time, both ends of the buffer box 50 is connected to the side member 25 and the bumper beam 30, respectively. That is, no separate stay is provided between the side member 25 and the bumper beam 30, and only the buffer box 50 exists so that the buffer box 50 serves as a kind of stay.

Accordingly, the shock applied to the vehicle can be more effectively absorbed by the shock absorbing box 50 filled with the absorbent internal foam 60 therein. In predicting the shock absorbing amount of the bumper assembly, the variable due to the presence of the stay disappears and only the amount absorbed by the buffer box 50 can be calculated and predicted, thereby enabling the design of the bumper assembly more precisely.

Hereinafter, the process of calculating the density of the absorbent internal foam through the compression test of the buffer box will be described in detail with reference to a graph.

First, Figure 8 (a) and Figure 8 (b) is shown in the test diagram the compression test process of the buffer box constituting an embodiment of the present invention.

As shown in the figure, the pressure piston (P) is pressed by pressing the upper surface of the buffer box 50 in a state that the buffer box 50 is seated on the die (D). In this process, a data value is obtained by measuring a compressive force (load) according to the deformation degree of the buffer box 50.

For reference, the housing 51 was a test object made of a heat-treated aluminum alloy, which is an alloy containing a certain ratio of silicon (si) (0.7 to 1.3%) and magnesium (mg) (0.6 to 1.2) in aluminum. It consists of. At this time, the heat treatment is performed by quenching by immersing the alloy in water after the solution treatment.

Such a housing 51 has the characteristics as shown in the following table. Of course, the following table shows an example of the characteristics of the material of the housing 51, and is not necessarily limited to the following numerical values.

Tensile Strength (MPa) Yield strength (MPa) Elongation (%) 327.8 297.5 11.4

First, the graph 1 below shows data when only the housing 51 of the buffer box 50 is compressed.

(Graph 1)

As shown in the figure, the compression load is greatly reduced when the housing 51 passes the initial displacement corresponding to the compressive yield strength. In this test, 3436.96 J of energy was required to compress the housing 51 by a total displacement of 60 mm, which means that the housing 51 absorbed 3436.96 J of energy during a 60 mm displacement. do.

Next, graph 2 below shows a test value when only the absorbent foam 60 is compressed without the housing 51.

(Graph 2)

As shown in the figure, in the case of the absorbent built-in foam 60, the compressive load does not decrease rapidly after the displacement corresponding to the yield strength, and even if the displacement increases, the compressive load is required to be higher than a predetermined level (15 kN). This is because the absorption embedded foam 60 can continuously absorb the compression energy while the pores 65 of the absorption embedded foam 60 are reduced. At this time, the absorption energy by the absorption embedded foam 60, that is, the compression energy required to deform the absorption embedded foam 60 is 941.17J.

Next, the following graph 3 shows the result of compressing the buffer box 50 into which the absorption inner foam 60 is inserted into the housing 51.

(Graph 3)

As shown in the figure, after the compressive force for compressing the buffer box 50 is initially large, it can be seen that the compressive force is greatly reduced after the displacement corresponding to the yield strength. However, unlike when only the housing 51 is tested, it can be seen that the compressive force is maintained at a constant level (100 kN), which means that the energy absorption of the buffer box 50 sufficiently occurs.

Precisely, the above test shows that the energy absorbed by the buffer box 50 is 6262 J in total, which is much larger than the summing of the two preceding data. From this, it can be seen that the energy absorption efficiency of the buffer box 50 composed of a separate material is superior to that provided only in the absorbent foam 60.

On the other hand, in the case of the absorbent foam 60, the density, that is, the proportion of pores 65 in the total volume (hereinafter referred to as 'porosity') is an important variable in determining the absorbed energy, such an absorbent foam ( The procedure for determining the appropriate density of 60) is described below.

First, graph 4 below is compression test data for an absorbent foam 60 made of aluminum having a density of 0.1 (g / cm ³ ). At this time, the total compressive energy (absorption energy) required for a total displacement of 60 mm is approximately 3000J.

(Graph 4)

Next, graph 5 below is compression test data conducted on an absorbent foam 60 made of aluminum having a density of 0.4 (g / cm ³ ).

At this time, the total compressive energy (absorption energy) required for a total displacement of 60 mm is approximately 5900 J, which can be seen to increase significantly compared to the previous test.

(Graph 5)

This test is repeated as shown in the graph 6 below the results of repeated tests varying the density of the absorbent interior foam (60).

More precisely, graph 6 below shows the absorbed energy and relative displacement. At this time, the absorbed energy means the compression energy required to compress the buffer box 50 by a predetermined displacement (60mm), and the relative displacement value is measured by measuring the displacement applied to the portion other than the buffer box 50 in this test process. The value subtracted from the displacement of the box 50 (displacement of the buffer box 50—displacement of the bumper beam 30—displacement of the side member 25).

   (Graph 6)

 As shown in the figure, it can be seen that as the density of the absorbent built-in foam 60 increases, the energy for deforming the buffer box 50 is increased by the same displacement.

At the same time, it can be seen that as the density of the absorbent foam 60 increases, the displacement of portions other than the buffer box 50, that is, the bumper beam 30 and the side member 25 increases.

At this time, the larger the absorbed energy by the buffer box 50 is better, but the deformation applied to the portion other than the buffer box 50 is preferably minimized. This is because the shock absorbing box 50 absorbs as much shock as possible to minimize the impact on other parts, especially the frame of the vehicle.

Accordingly, it is necessary to compromise the absorption energy and the relative displacement value of the buffer box 50, as shown in the graph, the density of the absorption built-in foam 60 is 0.2 ~ 0.5g / cm ³ It can be seen that the data satisfactorily satisfy both data when.

That is, the density of the absorption built-in foam 60 is 0.2 ~ 0.5g / cm ³ At this time, while the absorbed energy is ensured by the buffer box 50 or more, a shock applied to a portion other than the buffer box 50 is also kept below a certain level. This can be explained for the following reasons.

First, if the density of the absorption-embedded foam 60 is too small, the pore 65 is very large. In this case, energy absorption by the pores 65 may be well achieved during the compression process. This ratio is too large because the overall strength of the absorbent interior foam 60 is lowered, it can be seen that the effective energy absorption is difficult.

On the contrary, ii) if the density of the absorbent internal foam 60 is greater than a certain amount, the pores 65 become very small, and in this case, energy absorption by the pores 65 cannot be made well during the compression process, so that the buffer box 50 The impact is distributed to other parts.

Therefore, as can be seen in the graph, the density of the absorption built-in foam 60 is 0.2 ~ 0.5g / cm ³ (A range) is most preferred in terms of energy absorption efficiency.

Hereinafter, an operation when a shock is applied to a vehicle employing a bumper assembly of a vehicle according to the present invention will be described with reference to the drawings.

9 is a perspective view of a shock box deformed by the shock constituting an embodiment of the present invention.

First, when an impact is applied to the bumper cover 9 from the outside, an impact is transmitted to the bumper beam 30 provided in the bumper cover 9, and the shock transmitted to the bumper beam 30 is again buffered. The box 50 and the side member 25 are delivered in turn.

At this time, a large amount of impact energy is absorbed by the shock absorbing box 50 having a good shock absorption rate due to the characteristics of the material compared to other parts composed of ferrous metals.

More precisely, as shown in FIG. 9, the housing 51 and the absorbent internal foam 60 of the shock absorbing box 50 absorb the impact energy while compressively deforming, thereby minimizing the impact transmitted to other parts. It can be.

Accordingly, the operator may reuse only the bumper assembly by replacing only the shock absorbing box 50 deformed according to the degree of accident in the process of maintaining the vehicle after the vehicle is damaged. In particular, in the case of the buffer box 50 is composed of a separate body and the bumper beam 30 or the side member 25, it can be easily reassembled by removing it.

The scope of the present invention is not limited to the embodiments described above, but is defined by the claims, and various changes and modifications can be made by those skilled in the art within the scope of the claims. It is self evident.

In the above-described embodiment, the housing 51 is manufactured by heat-treating a material containing silicon and magnesium in a predetermined ratio in an aluminum material (6082-T6), but is not necessarily limited thereto, and other copper, chromium, or zinc is contained. It may be made of various aluminum alloy materials.

In addition, in the above embodiment, the front bumper of the vehicle is taken as an example, but is not limited thereto, and may be applied to the rear bumper of the vehicle.

1 is an exploded perspective view showing a bumper structure for a vehicle according to the prior art.

Figure 2 is a perspective view showing a frame structure of a vehicle employing a preferred embodiment of a vehicle bumper assembly using foamed aluminum according to the present invention.

3 is a perspective view showing the configuration of an embodiment of the present invention.

Figure 4 is a perspective view showing the configuration of a buffer box constituting an embodiment of the present invention.

Figure 5 is a perspective view showing the configuration of the absorbent interior foam constituting an embodiment of the present invention.

6 is a plan view showing the configuration of an embodiment of the present invention.

7 is a plan view showing another embodiment of the shock absorbing box constituting the bumper assembly for a vehicle using foamed aluminum according to the present invention.

8 (a) and 8 (b) is a test showing a compression test process of the buffer box constituting an embodiment of the present invention.

Figure 9 is a perspective view showing a state in which the shock absorbing box constituting the embodiment of the present invention modified by the impact.

Explanation of symbols on the main parts of the drawings

20: Front underbody 25: Side member

30: bumper beam 50: buffer box

51: housing 60: absorbent foam

65: pore

Claims (6)

A bumper beam provided on at least one of the front and the rear of the vehicle, The shock absorber is provided as a separate object between the bumper beam and the side member of the vehicle and absorbs the shock transmitted from the outside. A housing made of aluminum alloy having a storage space formed therein, 0.2g / cm ³ inserted into the storage space Bumper assembly for a vehicle using foamed aluminum, characterized in that it comprises an absorbent foam formed of foamed aluminum material having a density of ~ 0.5g / cm ³ . The vehicle bumper assembly of claim 1, wherein the absorbent foam is manufactured by mixing aluminum powder and foam powder which is a metal foaming agent, and heating by adding a thickener in a heater. The vehicle bumper assembly according to claim 1 or 2, wherein the shape of the cross section of the housing is formed in a regular polygon or a circle. 4. The vehicle bumper assembly of claim 3, wherein both ends of the buffer box are connected to the bumper beam and the side member, respectively. 5. The foaming apparatus as claimed in claim 4, wherein a partition wall is formed in the housing along the longitudinal direction of the storage space of the housing, and the absorbent foam is inserted into each storage space partitioned by the partition wall. Bumper assembly for vehicles using aluminum. 6. The vehicle bumper assembly according to claim 5, wherein a flange is provided at at least one end of both ends of the housing, and the flange is fastened to a bumper beam or a side member by a fastener or coupled by soldering. Blee.

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