Claims:We Claim:

1. A crash box (100) comprising:
a body portion (106) comprising:
a first member (102);
a second member (104), wherein the first member (102) is joined to the second member (104) to define a hollow cavity (108); and
a third member (105) disposed within the hollow cavity (108); and
at least one circumferential groove (103a, 103b, 103c) provided along length of body portion (106).
2. The crash box (100) as claimed in the claim 1, wherein each of the first member (102) and the second member (104) is a single-walled profile of substantially C-shaped cross section.
3. The crash box (100) as claimed in the claim 1, wherein the third member (105) is a reinforcing plate member coupled to at least one of the first member (102) and the second member (104).
4. The crash box (100) as claimed in the claim 1, wherein the at least one circumferential groove (103a, 103b, 103c) includes a first circumferential groove (103a), a second circumferential groove (103b), and a third circumferential groove (103c).
5. The crash box (100) as claimed in the claim 4, wherein each of the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) are positioned equidistant from one another along the length of the body portion (106) to facilitate progressive and stable axial collapse.
6. The crash box (100) as claimed in the claims 4 and 5, wherein each of the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) have a height of 8 mm.
7. The crash box (100) as claimed in the claim 6, wherein the first circumferential groove (103a) has 2 mm depth, the second circumferential groove (103b) has 1 mm depth, and the third circumferential groove (103c) has 0.5 mm depth.
8. The crash box (100) as claimed in the claims 4 to 7, wherein the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) are stamped on a flat sheet and then bent with minimum radius of 3 times the thickness of the sheet.
9. The crash box (100) as claimed in the claim 1, wherein each of the first member (102), the second member (104), and the third member (105) is made of sheet metal.
10. The crash box (100) as claimed in the claim 9, wherein each of the first member (102), the second member (104), and the third member (105) is made of aluminum or aluminum alloy.
11. The crash box (100) as claimed in the claim 9, wherein each of the first member (102), the second member (104), and the third member (105) is made of steel.
12. The crash box (100) as claimed in the claim 1, wherein the length of the body portion (106) is varied in the range of 125 to 130 mm.
13. The crash box (100) as claimed in the claim 12, wherein the length of the body portion is 125 mm.
14. The crash box (100) as claimed in the claim 1, wherein the perimeter of the body portion (106) is 304 mm.
15. The crash box (100) as claimed in the claim 1, wherein the crash box (100) is provided with a bumper device (120) of a vehicle.
16. The crash box (100) as claimed in the claim 1, wherein the first member (102), the second member (104) and the third member (105) are joined together by welding.
, Description:FIELD OF INVENTION
[0001] The present invention relates to a crash box, and more particularly to the crash box having a double cell axial design to enhance energy absorption performance during crash and prevent the severity of damage to passengers.

BACKGROUND
[0002] Improving the structural crashworthiness performance of an automobile is a major concern for most of vehicle manufacturers. Vehicles are equipped with energy absorbing structures such as bumpers having crash boxes to ensure the safety of passengers or reduce damage of a vehicle body in a vehicle collision. The crash boxes are provided between bumper and a side frame of the vehicle. Different shapes and structures are being used to make crash boxes and to improve their performance. Light weight designs to reduce greenhouse gas emissions have been accepted worldwide and become future trend of automotive development.
[0003] Conventional crash boxes are made up of thin steel sheets of Aluminium or thin steel sheets of AHSS grade for energy absorption and have different shapes such as circular, square, and multi-cells tubes etc. There have been some developments of FRP crash boxes as well. One example of such conventional crash box is shown in Figure 7. The crash box as shown in Figure 7, has a substantially rectangular shape and has benefits such as simple structural configuration, ease of manufacturability and cost effectiveness. However, it was found that even though crash boxes having simple shapes such as square, rectangle and circular are easy to manufacture, they do not qualify for high energy absorbing capacity during the crash (such as frontal crash) of the vehicle. Accordingly, a crash box which meets or exceeds energy absorption targets during a crash without increasing in size and without adding weight, or with a reduction in weight, is desirable.
OBJECTIVE OF INVENTION
[0004] It is an object of the invention to provide a double cell axial crash box design having improved the energy absorption of the crash member with nearly using same quantity of AHSS material.
[0005] It is an object of the invention to provide a crash box design which meets or exceeds energy absorption targets during a crash without increasing in size and without adding weight, or with a reduction in weight.
[0006] Another objective of the present invention to provide a crash box design which can effectively absorb the collision energy, thereby reducing the damages received by a vehicle body or an impact received by passengers of the vehicle.
SUMMARY OF INVENTION
[0007] This summary is provided to introduce concepts related to a double cell axial crash box design. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0008] In one aspect of the present invention, a crash box is provided. The crash box comprises a body portion. The body portion comprises a first member and a second member. The first member is joined to the second member to define a hollow cavity. The body portion also comprises a third member disposed within the hollow cavity. The crash box comprises at least one circumferential groove provided along length of body portion.
[0009] In an embodiment, each of the first member and the second member is a single-walled profile of substantially C-shaped cross section.
[0010] In an embodiment, the third member is a reinforcing plate member coupled to at least one of the first member and the second member.
[0011] In an embodiment, the at least one circumferential groove includes a first circumferential groove, a second circumferential groove, and a third circumferential groove. In an embodiment, each of the first circumferential groove, the second circumferential groove, and the third circumferential groove are positioned equidistant from one another along the length of the body portion to facilitate progressive and stable axial collapse. In an embodiment, each of the first circumferential groove, the second circumferential groove, and the third circumferential groove have a height of 8 mm.
[0012] In an embodiment, the first circumferential groove has 2 mm depth, the second circumferential groove has 1 mm depth, and the third circumferential groove has 0.5 mm depth.
[0013] In an embodiment, the first circumferential groove, the second circumferential groove, and the third circumferential groove are stamped on a flat sheet and then bent with minimum radius of 3 times the thickness of the sheet.
[0014] In an embodiment, each of the first member, the second member, and the third member is made of sheet metal. In an embodiment, each of the first member, the second member, and the third member is made of aluminum or aluminum alloy.
[0015] In an embodiment, each of the first member, the second member, and the third member is made of steel. In an embodiment, the first member, the second member and the third member are joined together by welding.
[0016] In an embodiment, the length of the body portion is varied in the range of 125 to 130 mm. In an embodiment, the length of the body portion is 125 mm. In an embodiment, the perimeter of the body portion is 304 mm.
[0017] In an embodiment, the crash box is provided with a bumper device of a vehicle.
[0018] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 illustrates a bumper device including a crash box, according to an embodiment of the present invention;
[0020] Figures 2, 3, 4, and 5 illustrate different views of the crash box, according to an embodiment of the present invention;
[0021] Figures 6(a) to 6(f) illustrate different views of the deformed crash box, according to an embodiment of the present invention;
[0022] Figure 7 illustrates a prior art crash box known in the art;
[0023] Figure 8 illustrates a graph showing peak force comparison of the crash box of the present invention and the prior art crash box, according to an embodiment of the present invention; and
[0024] Figure 9 illustrates a graph showing energy absorption comparison of the crash box of the present invention and the prior art crash box, according to an embodiment of the present invention.
[0025] The drawings referred to in this description are not to be understood as being drawn to scale except if specifically noted, and such drawings are only exemplary in nature.

DETAILED DESCRIPTION
[0026] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0027] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0029] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0030] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0031] Figure 1 illustrates a bumper device (120) including an exemplary crash box (100), according to embodiment of the present invention. The bumper device (120) extends in a lateral direction and is coupled to a frame (not shown) of a vehicle (not shown) via the crash box (100). The bumper (120) is made of materials including, but not limited to metal, hardened plastic etc. The bumper device (120) along with the crash box (100) may be provided in front part of the vehicle or the rear part of the vehicle, without limitations. In the illustrated example, the bumper device (120) is coupled to the frame via two crash boxes (100). The crash boxes (100) are provided between a bumper reinforcement (not shown) of the bumper device (120) and the frame of the vehicle (not shown). The crash boxes (100) have an identical structure and for the sake of clarity and simplicity the description now will be described in reference to only one crash box however, the description is equally applicable to both the crash boxes without any limitations.
[0032] Referring to Figures 2 to 6, the crash box (100) having a double cell axial design comprises a body portion (106) extending in the longitudinal direction between the bumper device (120) and the frame of the vehicle. The crash box (100) may comprise an additional attaching plate arranged at an end. The attaching plate facilitates in coupling the crash box (100) to the frame of the vehicle. In the preferred embodiment, the crash box (100) is welded to the bumper device (120) and the frame of the vehicle. Alternatively, the crash box (100) may be fastened using fastening members, without limiting the scope of the invention.
[0033] The body portion (106) comprises a first member (102), a second member (104) and a third member (105). The first member (102) is joined to the second member (104) to define a hollow cavity (108) (shown in Figure 4). In the illustrated embodiment, each of the first member (102) and the second member (104) is a single-walled profile of substantially C-shaped cross section. The third member (105) disposed within the hollow cavity (108). The third member (105) is a reinforcing plate member coupled to at least one of the first member (102) and the second member (104).
[0034] Each of the first member (102), the second member (104), and the third member (105) is made of sheet metal. In the preferred embodiment, each of the first member (102), the second member (104), and the third member (105) is made of steel of AHSS grade. In another embodiment, each of the first member (102), the second member (104), and the third member (105) is made of aluminum or aluminum alloy. In another embodiment, each of the first member (102), the second member (104), and the third member (105) is made of fiber reinforced plastic (FRP), without limiting the scope of the invention.
[0035] In the preferred embodiment, each of the first member (102), the second member (104), the third member (105) have the same thickness as one another. In the preferred embodiment, the first member (102), the second member (104), and the third member (105) are joined by welding. In another embodiment, the first member (102), the second member (104) and the third member (105) may be joined in a variety of ways, e.g., fasteners, and/or with adhesives etc., without any limitations.
[0036] In the preferred embodiment, the length of the body portion (106) can be varied in the range of 120 to 350 mm. In the illustrated example, the length of the body portion is 125 mm. In the illustrated example, the perimeter of the body portion (106) is 304 mm. In the illustrated example, length of long side of the body portion (106) is 86.84 mm and length of short side of the body portion (106) is 44.3 mm.
[0037] The crash box (100) comprises at least one circumferential groove (103a, 103b, 103c) provided along length of body portion (106) which will aid in stable deformation and it will help in decreasing the peak force. Each of the at least one circumferential groove (103a, 103b, 103c) extends into the inner area from an outer surface (130) of the body portion (106).
[0038] In the illustrated example, the crash box (100) comprises three circumferential grooves (103a, 103b, 103c) including a first circumferential groove (103a), a second circumferential groove (103b), and a third circumferential groove (103c) (shown in Figures 2 and 3). In the illustrated embodiment, each of the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) are positioned equidistant from one another along the length of the body portion (106). In one example, the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) are positioned at a distance of 33.73 mm from one another along the length of the body portion (106). The first circumferential groove (103a) is positioned at a distance of 23.81 mm from an upper edge (130) of the body portion (106). The third circumferential groove (103c) is positioned at a distance of 21.83 mm from a lower edge (132) of the body portion (106).
[0039] In the preferred embodiment, each of the first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) have a height of 8 mm. The first circumferential groove (103a) has 2 mm depth, the second circumferential groove (103b) has 1 mm depth, and the third circumferential groove (103c) has 0.5 mm depth (shown in Figure 2).
[0040] The first circumferential groove (103a), the second circumferential groove (103b), and the third circumferential groove (103c) are stamped on a flat sheet and then the flat sheet is bent with minimum radius in the range of 2t to 4t, wherein the “t” is thickness of the sheet. In the preferred embodiment, the flat sheet is bent with minimum radius 3 times the thickness of the sheet to form each of the first member (102) and the second member (104).
[0041] The hollow cavity (108) of the body portion (106) may be filled with a flexible cushion material for example, a gel, a fluid, or a solid material that becomes a liquid when under pressure (such as silicone), without limiting the scope of the invention.
[0042]
[0043] Figures 6 (a) to (f) illustrate different views of the crash box (100) under the collision load. In a vehicle impact event, the crash box (100) receives collision load (compression load) resulted from an impact applied to the vehicle via the bumper reinforcement, the body portion (106) starts its buckling deformation with deformation starting at the first circumferential groove (103a) (as shown in Figure 6 (b)), gradually moving towards the second circumferential groove (103b) (as shown in Figure 6 (c)) and so on (as shown in Figure 6 (d) to 6 (e)). The double cell axial design is such that the crash box (100) absorbs the impact energy, thus relieving the impact applied to the frame and like structural members of the vehicle. The crash box (100) as described above exceeds energy absorption targets during a crash without increasing in size, without adding weight and without compromising on the ease of manufacturability, as compared to the conventional crash box (200).
[0044] Referring to Figures 8 and 9, graphs showing performance of the crash box (100) according to the principles of the present invention as compared to the conventional crash box (as shown in Figure 7) are illustrated. Vehicles with crash box (100) and the conventional crash box (as shown in Figure 7) were subjected to an impact with a rigid wall at a speed under 50 KMPH. Both the crash boxes were made from AHSS material and weighed 370 grams.
[0045] In Figures 8 and 9, the purple line shows the performance of the crash box (100) and the red line shows the performance of the prior art crash box (200). The peak force of the crash box (100) of the present invention is same as the deflection of the prior art crash box (200) (conventional crash box (200)), however the average force of the crash box (100) is higher than the prior art crash box (200). The initial peak force is also very low which will protect the passengers from the injury by excessive deceleration. In addition, the total absorbed energy of the crash box (100) is 96% greater than the prior art crash box (200) (conventional crash box (200)). The energy absorption of rectangular design of prior art crash box (200) was found to be is 3.2 kJ and that of proposed crash box (100) was found to be 6.5 kJ, thereby showing a 96 % increase in energy absorption. Further, it has been observed from the above plots as shown in Figures 8 and 9, that the average force of the crash box (100) is not degrading with deflection.
[0046] The present invention relates to the crash box (100) disposed between the bumper device (120) and the frame of vehicle. The double cell axial design of the crash box (100) absorbs more collision energy by compressively plastically deforming in the front-rear direction of the vehicle at the time of a collision, thereby reducing the damages received by a vehicle body or an impact received by passengers of the vehicle. The crash box (100) exceeds energy absorption targets during a crash without increasing in size, without adding weight and without compromising on the ease of manufacturability, as compared to the conventional crash box (200).
[0047] Furthermore, the terminology used herein is for describing embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0048] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0049] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.