Vehicle front structure for improved compatibility during a frontal crash

Abstract

The present disclosure relates to a Vehicle front structure as defined above is provided, in which the front structure comprises: a side member for supporting a vehicle bumper beam, the side member extending along a longitudinal axis between a first end for connecting to the vehicle bumper beam and a second end for connecting to a bulkhead, and a lateral extension member extending substantially perpendicular with respect to the longitudinal axis of the side member and outward with respect to the vehicle front structure, the lateral extension member is connected to the side member such that the lateral extension member can exert a bending moment to the side member, and a bending strength of the lateral extension member in backward direction towards the side member is higher compared to a bending strength in the forward direction away from the side member.

Claims

1. Vehicle front structure, comprising: a side member for supporting a vehicle bumper beam, the side member extending along a longitudinal axis between a first end for connecting to the vehicle bumper beam and a second end for connecting to a bulkhead, and a lateral extension member extending substantially perpendicular with respect to the longitudinal axis of the side member and outward with respect to the vehicle front structure, the lateral extension member being connected to the side member and the lateral extension member being configured to exert a bending moment to the side member, and a bending strength of the lateral extension member in a backward direction towards the side member being higher compared to a bending strength in a forward direction away from the side member.

2. The vehicle front structure according to claim 1, the lateral extension member being connected to the side member at the first end of the side member.

3. The vehicle front structure according to claim 1, the vehicle front structure comprising: a bumper beam, an impact absorbing unit connected to the bumper beam and the first end of the side member, and defining a deformation zone between the bumper beam and the side member for smooth reduction of a vehicle impact velocity, a mounting system for mounting the lateral extension member to the impact absorbing unit and/or the first end of the side member, and configured to exert the bending moment to the side member.

4. The vehicle front structure according to claim 3, the lateral extension member extending further than the bumper beam for increasing an impact surface facing the forward direction.

5. The vehicle front structure of claim 3, the mounting system connecting both to the impact absorbing unit and the first end of the side member.

6. The vehicle front structure of claim 3, the mounting system being configured for mounting the lateral extension member through both a retaining support and a bearing support.

7. The vehicle front structure of claim 3, the mounting system comprising a cellular structure and comprising at least two cells for accommodating at least a portion of the lateral extension member.

8. The vehicle front structure of claim 3, the lateral extension member being arranged between the bumper beam and the side member.

9. The vehicle front structure of claim 1, the lateral extension member comprising a T-shaped cross section for increasing the impact surface facing the forward direction.

10. The vehicle front structure of claim 1, the lateral extension member comprising a weakened section for determining a failure load and/or failure mechanism of the lateral extension member.

11. The vehicle front structure of claim 10, the weakened section comprising a through hole.

12. The vehicle front structure of claim 3, the lateral extension member comprising a mounting projection for accommodating in the mounting system, and the mounting projection being coupled to the mounting system through fastening means like a pair of bolts.

13. The vehicle front structure of claim 12, the lateral extension member comprising a pair of mounting projections, and at least one of the pair of mounting projections being accommodated in the mounting system with a sliding fit.

14. The vehicle front structure of claim 12, the at least one of the pair of mounting projections comprising a bevelled end for facilitating swivelling of the at least one of the pair of mounting projections out of the mounting system.

15. The vehicle front structure of claim 3, the lateral extension member comprising a stop surface abutting the mounting system for exerting the bending moment to the side member and activating side member deformation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present disclosure will be discussed in more detail below, with reference to the attached drawings, in which:

[0040] FIG. 1 depicts a front view of a vehicle front structure according to the disclosure;

[0041] FIG. 2 depicts a top view of the front structure of FIG. 1;

[0042] FIG. 3 depicts a part of the front structure of FIGS. 1 and 2 in an initial phase of a frontal crash;

[0043] FIG. 4 depicts a detail of the front structure in a later phase of the frontal crash;

[0044] FIG. 5 depicts a schematic top view of a phase during a crash test;

[0045] FIG. 6 shows a lateral extension member in different load conditions;

[0046] FIG. 7 depicts a cross sectional perspective view of an extension member and mounting system; and FIG. 8 depicts a cross sectional perspective view of an extension member.

DESCRIPTION OF EMBODIMENTS

[0047] FIG. 1 and FIG. 2 depict an embodiment of a vehicle front structure according to the disclosure. The passenger vehicle front structure 1, comprises a side member 2. In most cases the front structure 1 has symmetry and thus the passenger vehicle front structure 1 comprises two side members 2. The pair of side members 2 are arranged at opposite sides of the front structure 1. The side member extends along a longitudinal axis 7. The side member 2 extends between a first end 8 and a second end 9. The vehicle front structure 1 comprises a bumper beam 4. The first end 8 of the side member 2 connects to the vehicle bumper beam 4. The second end 9 of the side member 2 connects to a bulkhead (not shown). The vehicle bumper beam 4 and side members 2 as well as the impact absorbing units 6 do form part of a passive safety system that determines how well a vehicle performs under crash load conditions. The second end 9 of the side member 2 may connect to any suitable other part of a vehicle structure as long as it is clear that a passive safety system is formed. The side members 2 support the vehicle bumper beam 4. The side member 2, as well as the bumper beam 4 is configured to deform under defined load conditions and will therefore absorb impact energy during a vehicle crash.

[0048] The passenger vehicle front structure 1, comprises a lateral extension member 3. Lateral is to say that the extension member 3 extends substantially perpendicular with respect to the longitudinal axis 7 of the side member 2. The extension member 3 extends outward with respect to the vehicle front structure 1. The lateral extension member 3 is arranged between the bumper beam 4 and the side member 2 as seen along the longitudinal axis 10 of vehicle front structure 1. Here, the lateral extension member 3 extends further than the bumper beam 4. The lateral extension member 3 provides an increase of an impact surface. “Impact surface” is the effective surface that can bear a crash load and faces a, in this case forward, direction. The lateral extension member 3 is connected to the side member 2. The lateral extension member 3 is connected to the side member 2 at the first end 8 of the side member 2.

[0049] The lateral extension member 3 is connected to the side member 2 such that the lateral extension member 3 can exert a bending moment to the side member 2. The lateral extension member 3 is configured such that a bending strength of the lateral extension member 3 in the backward direction towards the side member 2 is higher compared to a bending strength in the forward direction away from the side member 2.

[0050] The passenger vehicle front structure 1 comprises in this case an impact absorbing unit 6. Such an impact absorbing unit 6 is also referred to as a “crash box”. The impact absorbing unit 6 is connected to the bumper beam 4 and the first end 8 of the side member 2. Here, the side member 2 is thus indirectly connected to the bumper beam 4. The side member 2 is indirectly connected to the bumper beam 4 through the impact absorbing unit 6. The side member 2 is indirectly connected to the bumper beam 4 via the impact absorbing unit 6. The impact absorbing unit 6 is a part that is designed and configured to define a deformation zone between the bumper beam 4 and the side member 2. The impact absorbing unit 6 importantly contributes to a smooth reduction of a vehicle impact velocity.

[0051] The passenger vehicle front structure 1 comprises a mounting system 5 for mounting the lateral extension member 3 to the vehicle front structure 1. In this case, the mounting system 5 connects the lateral extension member 3 to the impact absorbing unit 6. The effect thereof is that the later extension member can initiate deformation of the side member independently of a crash load to the bumper beam 4. This is beneficial in some crash load cases and provides the ability to balance deformation between the bumper beam 4, the impact absorbing unit 6 and the side member 2. Here, the mounting system 5 connects indirectly to the side member 2 through a mounting plate 11a, 11b.

[0052] As alternative to the embodiment shown in FIGS. 1 and 2 it is conceivable that the mounting system 5 connects directly to the first end 8 of the side member 2. This may however reduce an effective length of the side member 2 for deformation initiated by the lateral extension member 3. Here, “effective length” is the length available for deformation. It is also conceivable that the mounting system 5 connects both to the impact absorbing unit 6 and the first end 8 of the side member 2.

[0053] The deformed vehicle front structure 1 according to the disclosure will now be described under reference to FIGS. 3, 4 and 5.

[0054] FIG. 3 depicts a part of the front structure of FIGS. 1 and 2 in an initial phase of a frontal crash. In this initial phase of a frontal crash, the lateral extension member 3 is still in its initial engagement with the mounting system 5. The extension member 3 is coupled to the mounting system 5 through both a retaining support and a bearing support as will be explained below. This connection facilitates exertion of a bending moment to the side member 2. As indicated, a crash load Fc has been exerted to the lateral extension member 3. As a consequence, the lateral extension member 3 has initiated deformation of the side member 2. The deformation of the side member 3 includes buckling and bending in this case. The severe crash has also deformed the bumper beam 4 as well as the impact absorbing unit 6. As a result the impact energy has been distributed between the side member 3, the bumper beam 4 as well as the impact absorbing unit 6.

[0055] FIG. 4 depicts a detail of the front structure in a later phase of the frontal crash. In this later phase of the frontal crash, the lateral extension member 3 is out of its initial engagement with the mounting system 5. The lateral extension member 3 is bent forward with respect to the mounting system 5. The lateral extension member 3 is partly out of contact with the mounting system 5. The extension member 3 is now coupled to the mounting system 5 through a retaining support while the bearing support is out of contact. As indicated, the bending forward of the extension member 3 is caused by a secondary force Fs that is exerted to the lateral extension member 3. This load Fs is or can be exerted by a wheel structure (not shown). This load is called secondary force here because it can be regarded as an internal force as a response to the crash load. The deformation of the side member 3 has progressed and includes even more buckling and bending in this case. Likewise, the bumper beam 4 as well as the impact absorbing unit 6 have progressively been deformed. As a result the impact energy has been distributed between the side member 3, the bumper beam 4 as well as the impact absorbing unit 6, whereas at the same time, stack up of material in the backward direction is reduced. The backward direction is from the vehicle front structure 1 to a vehicle passenger compartment (not shown).

[0056] FIG. 5 depicts a schematic top view of a certain phase during a crash test. As general info: The EU-NCAP, the European New CAR Assessment Program, has developed a new frontal offset method to rate the crash performance and crash compatibility against other cars. The new test, MPDB (Moving Progressive Deformable Barrier), consists of a moving progressively deformable barrier 26. According to this new method, the deformation of the barrier 26 is measured and rated. An evenly distributed impression is promoted and results in higher rating. This adds to the complexity when designing the front structure of cars. As explained above, the effect of the current disclosure is that load to a partner vehicle 24 is evenly distributed during an initial phase of a frontal crash. The more even distribution of the crash load over the deformable barrier 26 is possible because the lateral extension member 3 enables dividing the crash load between the bumper beam 4 and the side member 2 because the later extension member initiates deformation of the side member 2. In this case, a portion of the crash load is also directed towards the impact absorbing unit 6. As shown, here the lateral extension member 3 is still in its initial engagement with the mounting system 5. However, the wheel structure 25 just contacts the lateral extension member 3 and soon will exert the secondary force Fs to the lateral extension member 3.

[0057] The lateral extension member 3 and its mounting system is now described in more detail referring to FIGS. 6, 7 and 8.

[0058] The lateral extension member (3) comprises a T-shaped cross section 14. The T-shaped cross section 14 results in an increase of the impact surface facing the forward direction that is towards a partner vehicle in a frontal crash situation. The lateral extension member 3 comprises a mounting projection 15a, 15b. The mounting projection 15a, 15b connects the lateral extension member 3 to the mounting system 5. The lateral extension member 3 comprises a weakened section 18. The weakened section is arranged between the T-shaped cross section 14 and the mounting projection 15a, 15b. The weakened section 18 determines a failure load and/or failure mechanism of the lateral extension member 3. Here, the weakened section 18 comprises a through hole 19. The through hole 19 facilitates deformation of even rupture of the later extension member 3.

[0059] The lateral extension member 3 comprises a pair of mounting projections 15a, 15b in this case. The pair of mounting projections 15a, 15b form a forked section facing the mounting system 5. Here, both the mounting projections 15a, 15b are accommodated in the mounting system 5. The forward mounting projection 15b is coupled to the mounting system through a fastening means, here a pair of retaining bolts 16a, and 16b. Thus the forward mounting projection 15b is coupled to the mounting system 5 through a retaining support. The forward mounting projection 15b that is retained with the mounting system 5, comprises the weakened section 18. The backward mounting projection 15a is accommodated in the mounting system 5 with a sliding fit. The sliding fit facilitates that the backward mounting projection 15a can slide out of contact with the mounting system 5. The backward mounting projection 15a comprises a bevelled end 17. The bevelled end 17 facilitates even more swivelling of the backward mounting projection 15a out of the mounting system 5.

[0060] FIG. 7 depicts a cross sectional perspective view of the extension member 3 and the mounting system 5. In this case, the mounting system 5 comprises a cellular structure 13 that provides strength at a low weight. The cellular structure 13 has three cells 12a, 12b, and 12c. These cells 12a, 12b, 12c can have a closed continuous wall 22. It is possible to have a different number of cells like shown in FIG. 6 that adds a fourth cell 12d. The cellular structure 13 accommodates a portion of the lateral extension member 3. Here, both the mounting projections 15a, 15b are accommodated in the mounting system 5. Each of the both mounting projections 15a, 15b is accommodated in a respective cell 12b, 12c of the cellular structure 13 of the mounting system 5. A cell wall section 22a is accommodated in an empty space 23 between the mounting projections 15a, 15b. The backward mounting projection 15a is accommodated in the mounting system 5 with a sliding fit. The backward mounting projection 15a is in bearing contact with the mounting system 5. Thus the backward mounting projection 15a is coupled to the mounting system 5 through a bearing support. The backward mounting projection 15a is in bearing contact with the mounting system 5 through a stop surface 20a of the lateral extension member 3. The stop surface 20a contacts the cell wall 22 of the mounting system 5. In this case a pair of stop surfaces 20a, 20b flank the backward mounting projection 15a and both contact the cell wall 22 of the mounting system 5. Thus the extension member 3 is coupled to the mounting system 5 through both a retaining support and a bearing support. The retaining support comprises the weakened section 18.

[0061] As can be best seen in FIG. 8, the lateral extension member 3 comprises the stop surface 20a. Here, the lateral extension member 3 comprises a pair of stop surfaces 20a, 20b. The pair of stop surfaces 20a, 20b are arranged at opposite sides of the lateral extension member 3. The pair of stop surfaces 20a, 20b flank the backward mounting projection 15a. The pair of stop surfaces 20a, 20b abut the mounting system 5 for exerting the bending moment to the side member 2 and activating side member deformation.