Beam assembly for an underrun protection system of a vehicle, underrun protection system, and vehicle

Abstract

A beam assembly (20) for an underrun protection system (10) of a vehicle (1). The beam assembly (20) comprises a first profile (30), a second profile (40), and third profile (50), each in the form of an open steel profile extending longitudinally in the longitudinal direction (L) of the beam assembly (20). The first profile (30) comprises a first leg portion (31) arranged to form an outward side (23) of the beam assembly (20) and a second leg portion (32) arranged to form an underside (22) of the beam assembly. The second profile (40) comprises a third leg portion (41) arranged at an angle (α) of 75- 105° relative to the first leg portion (31), and a fourth leg portion (42) arranged to form part of an inward side (24) of the beam assembly (20). The third profile (50) comprises a fifth leg portion arranged to form an upper side (21) of the beam assembly (20). The third profile (50) is, at its first free end (50a), attached to the first profile (30) and, at its second free end (50b), attached to the second profile (40).

Description

[0001] BEAM ASSEMBLY FOR AN UNDERRUN PROTECTION SYSTEM OF A VEHICLE, UNDERRUN

[0002] PROTECTION SYSTEM, AND VEHICLE

[0003] TECHNICAL FIELD

[0004] The present disclosure relates in general to a beam assembly for an underrun protection system of a vehicle. Moreover, the present disclosure relates in general to an underrun protection system for a vehicle. The present disclosure also relates in general to a vehicle.

[0005] BACKGROUND

[0006] Underrun protection systems for heavy-duty or medium-duty vehicles are designed to enhance safety by preventing smaller vehicles, such as cars, from sliding or rolling underneath the heavy-duty or medium-duty vehicle in the event of a collision. Underrun protection systems play a crucial role for reducing the severity of crashes involving heavy-duty or medium-duty vehicles and passenger cars, enhancing safety for occupants of smaller vehicles.

[0007] An underrun protection system comprises an underrun beam, often made of steel. The underrun beam may sometimes comprise two or more profiles, such as two C-shaped profiles, assembled to jointly form the underrun beam. The underrun beam is in turn mounted to the chassis of the vehicle by means of a support structure of the underrun protection system.

[0008] An underrun beam of an underrun protection system is not only intended to prevent underrun of smaller vehicles, but also to absorb and dissipate a part of the impact energy generated in case of a collision in a way that protects the smaller vehicle's occupants. Suitably, the underrun beam should also protect constituent components of the heavy-duty or medium-duty vehicle, which are essential for safe operation of the vehicle, from damage in case of a collision. The underrun beam should therefore have a high strength and high stiffness, as well as good structural integrity.

[0009] Underrun beams today often have a hollow circular or rectangular (including square) cross section, which in turn means that they need to have a relatively large wall thickness to reach sufficient strength to avoid the underrun beam from collapsing when a force is applied across the profile due to a collision. Such a wall thickness may lead to an unduly high weight of the underrun beam, which in turn contributes to the weight of the vehicle as such.

[0010] SUMMARY

[0011] The object of the present invention is to provide an improved beam assembly for an underrun protection system of a vehicle, to thereby increase safety of other road users as well as the vehicle in the event of a collision of the vehicle.

[0012] The object is achieved by the subject-matter of the appended independent claim(s).

[0013] In accordance with the present disclosure, a beam assembly for an underrun protection system of a vehicle is provided. The beam assembly has, as seen in relation to its orientation when arranged in the vehicle, an upper side, an underside, an outward side, and an inward side. The beam assembly comprises a plurality of open steel profiles extending longitudinally in a longitudinal direction of the beam assembly. The plurality of open steel profiles comprises a first profile, a second profile, and a third profile.

[0014] The first profile has a cross section, perpendicular to its longitudinal extension, comprising: a first leg portion arranged to form the outward side of the beam assembly, a second leg portion arranged to form the underside of the beam assembly, and optionally a web portion connecting the first and second leg portions.

[0015] The second profile has a cross section, perpendicular to its longitudinal extension, comprising: a third leg portion arranged at an angle of 75-105° relative to the first leg portion of the first profile, a fourth leg portion arranged to form at least a part of the inward side of the beam assembly, a first flange portion extending from the third leg portion, the first flange portion being attached to the first leg portion or the optional web portion of the first profile, a second flange portion extending from the fourth leg portion, the second flange portion being attached to the second leg portion of the first profile, and optionally an intermediate portion connecting the third leg portion with the fourth leg portion. The third profile has a cross section, perpendicular to its longitudinal extension, comprising: a fifth leg portion arranged to form the upper side of the beam assembly, and a first free end portion and a second free end portion.

[0016] The third profile is, at its first free end portion, attached to the first leg portion of the first profile. Moreover, the third profile is, at its second free end portion, attached to the fourth leg portion of the second profile or the optional intermediate portion of the second profile.

[0017] The herein described beam assembly has a considerably higher stiffness compared to e.g., a previously known underrun beam having a hollow rectangular or circular cross section (even if made of the same high-strength material at similar weight). Moreover, the configuration of the beam assembly leads to a reduced risk of the upper side and the lower side of the beam assembly buckling in a vertical direction (i.e. up and / or down as seen in relation to its orientation when arranged in a vehicle; that is, a direction which is perpendicular to the longitudinal direction of the beam assembly) when the outward side of the beam assembly is subjected to an impact force in case of a collision.

[0018] The increased stiffness, as well as the reduced risk for buckling, in turn leads to an improved ability of the beam to absorb and dissipate impact energy in case it is subjected to impact. The increased stiffness and ability of absorb impact energy are inter alia a result of the third leg portion of the second profile acting as a reinforcing member when the beam assembly is subjected to impact against the first leg portion of the first profile in case of a collision of a vehicle comprising the beam assembly. Thus, the risk of the beam assembly collapsing at crash is reduced.

[0019] Moreover, the herein described beam assembly also has an excellent structural stability in view of the first, second and third profiles not being attached to each other at a common attachment. This means that, even though one attachment would crack or otherwise fail due to an impact force in the event of a collision, the beam assembly would still hold and maintain a reasonable stiffness, and thereby still be able to dissipate the impact energy as intended.

[0020] The herein described beam assembly also allows for considerably thinner wall thicknesses of the plurality of profiles compared to, for example, an underrun beam having a hollow rectangular or circular cross section having a similar strength and stiffness. This allows for reducing the weight of the beam assembly, and thereby contributing to lower weight of a vehicle comprising the beam assembly. In view of the foregoing, the herein described beam assembly provides a good balance between high stiffness, ability to absorb and dissipate impact energy, and weight of the beam assembly.

[0021] The second leg portion of the first profile may be arranged perpendicular to, or with an obtuse angle relative to, the first leg portion of the first profile. This contributes to the high stiffness of the beam assembly.

[0022] The second leg portion of the first profile may be connected to the first leg portion via a curved connection portion. Thereby, the risk of the first profile cracking between the first and second leg portions in case the beam assembly is subjected to impact during a potential collision of a vehicle, comprising the beam assembly, may be reduced. Furthermore, a curved connection portion may also contribute to increased stiffness.

[0023] According to a first alternative of the second profile, the third leg portion and the fourth leg portion of the second profile may together form a L-shaped profile section.

[0024] According to a second alternative of the second profile, the intermediate portion of the second profile may extend in a plane that is substantially parallel to a plane in which the fourth leg portion of the second profile extends, and / or the intermediate portion may be arranged substantially perpendicular to the third leg portion of the second profile. The intermediate portion may for example facilitate positioning of the third profile relative to the second profile during production of the beam assembly, which in turn may facilitate attachment of the second free end portion of the third profile to the second profile. Moreover, such an intermediate portion may allow the third profile to be arranged substantially flush with the fourth leg potion of the second profile, if desired.

[0025] According to a first alternative of the third profile, the third profile may have a cross section, perpendicular to its longitudinal extension, that further comprises a sixth leg portion that is angled relative to the fifth leg portion, suitably with an obtuse angle. Moreover, in such a case, the second free end portion of the third profile may be formed of a fourth flange portion extending from the sixth leg portion. This improves the shearing strength of the third profile and therefore also improved stiffness of the beam assembly.

[0026] According to a second alternative of the third profile, the third profile may constitute a Z-profile in which the fifth leg portion constitutes a web of said Z-profile. This may contribute to reduced risk of the upper side of the beam assembly buckling in a vertical direction in case the outward side of the beam assembly is subjected to an impact force. Reduced risk for such buckling in turn leads to improved ability for the beam assembly to distribute the impact force as intended.

[0027] The third leg portion of the second profile may comprise a plurality of through-holes distributed along the longitudinal extension of the second profile. This has the advantage of further increasing the stiffness of the beam assembly due to affecting the force distribution within the beam assembly. Moreover, the plurality of through-holes also contributes to a reduction in weight.

[0028] The first profile may further comprise a curved stiffening portion protruding upwards towards the second profile (when seen in the cross sectional view of the first profile), said curved stiffening portion being connected to the second leg portion of the first profile. Such a curved stiffening portion, if present, leads to a further increase in the stiffness of the beam assembly.

[0029] The beam assembly may further comprise a first mounting region and a second mounting region, separated from each other in the longitudinal direction of the beam assembly, each of the first and second mounting regions being configured for mounting of a support structure and / or an energy absorbing member of the underrun protection system. Moreover, each of the first, second, and third profiles may extend longitudinally at least between the first and second mounting regions. Thereby, the beam assembly will have an excellent stiffness and ability to dissipate the impact energy in a way that increases the safety both for the vehicle comprising the beam assembly as well as occupants of a smaller vehicle in the event of a crash.

[0030] The present disclosure also relates to an underrun protection system for a vehicle, said underrun protection system comprising the beam assembly as described above. The underrun protection system may be a front underrun protection system, but is not limited thereto.

[0031] The underrun protection system provides the advantages already described above with regard to the beam assembly.

[0032] The underrun protection system may further comprise a first energy absorption member and a second energy absorption member, each of the first and second energy absorption members being attached (suitably mounted) to the beam assembly. This may increase the ability for the underrun protection system to absorb energy generated as a result of impact during a possible collision and thereby increases safety. The underrun protection system may further comprise a support structure configured to support the beam assembly relative to a chassis of the vehicle when the underrun protection system is arranged in the vehicle.

[0033] The present disclosure further relates to a vehicle comprising the above described beam assembly. The vehicle may be a medium-duty or a heavy-duty vehicle.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 schematically illustrates a side view of an example of a vehicle,

[0036] Fig. 2 schematically illustrates a perspective view of a first exemplifying embodiment of an underrun protection system for a vehicle according to the present disclosure,

[0037] Fig. 3 illustrates a cross-sectional view of a first exemplifying embodiment of the herein described beam assembly,

[0038] Fig. 4 illustrates a cross-sectional view of a second exemplifying embodiment of the herein described beam assembly,

[0039] Fig. 5 illustrates a cross-sectional view of a third exemplifying embodiment of the herein described beam assembly,

[0040] Fig. 6 illustrates a cross-sectional view of a fourth exemplifying embodiment of the herein described beam assembly,

[0041] Fig. 7 illustrates a cross-sectional view of a fifth exemplifying embodiment of the herein described beam assembly,

[0042] Fig. 8 illustrates a cross-sectional view of a sixth exemplifying embodiment of the herein described beam assembly, and

[0043] Fig. 9 illustrates a perspective view of (part of) a first alternative embodiment of the second profile of the herein described beam assembly. DETAILED DESCRIPTION

[0044] The invention will be described in more detail below with reference to exemplifying embodiments and the accompanying drawings. The invention is however not limited to the exemplifying embodiments discussed and / or shown in the drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate the invention or features thereof.

[0045] The herein described beam assembly comprises a plurality of open profiles, as will be discussed in detail below. As is well known in the art, an open profile is a profile that has an open, non-enclosed geometry. In other words, an open profile has at least two free ends when seen in a cross section perpendicular to its longitudinal extension. Furthermore, an open profile does not, in contrast to e.g., a hollow profile or a tube, provide an enclosed shape when seen in cross section. Common examples of open profiles include L-profiles, T-profiles, U-profiles, etc.

[0046] In the present disclosure, the term "open steel profile" is used to describe an open profile made of steel. It is considered to encompass open profiles of steel which may or may not be coated, for example painted or lacquered, or otherwise surface treated (e.g., galvanized).

[0047] Furthermore, in the present disclosure, an outward side of a beam assembly is considered to mean a side of the beam assembly arranged to, or at least intended to be arranged to, face towards the exterior of a vehicle when the beam assembly is arranged in the vehicle. The outward side of the herein described beam assembly thus corresponds to the side of the beam assembly which is arranged to face impact in case of collision of a vehicle comprising the beam assembly with an obstacle and / or another road user. An inward side of a beam assembly is considered to mean a side of the beam assembly arranged to, or at least intended to be arranged to, face towards the interior or center of a vehicle when the beam assembly is arranged in the vehicle.

[0048] The term "web" (or "web portion") is in the present disclosure considered to mean a part of a profile which connects two other parts of the profile, for example two leg portions or two flange portions, when seen in a cross section perpendicular to the longitudinal extension of the profile. An L-profile is a profile consisting of two perpendicularly arranged leg portions that are directly connected to each other, often by a rounded corner, such that the profile has a cross section having a shape resembling the letter L. Similarly, in the present disclosure, a L-shaped profile section is considered to mean a section of a profile that consists of two leg portions that are directly connected to each other, e.g. by a rounded corner, and that extend perpendicular to each other. A profile which comprises a L-shaped profile section may comprise one or more further profile sections connected to the L-shaped profile section. For example, one or more flanges may be connected to L-shaped profile section. In case such one or more flanges are connected to the L-shaped profile section at its respective ends (i.e. the ends of the respective leg portions that are not connected to the other leg portion), the profile may be described as a flanged L-shaped profile or as having a flanged L-shaped profile cross section.

[0049] A Z-profile is a profile consisting of two flat portions (for example two leg portions, two flange portions, or one leg portion and one flange portion) that are connected by a web. The two flat portions are arranged in parallel and extend in opposite directions from the web such that the profile has a cross section having a shape resembling the letter Z. The web may extend perpendicular to each of the two flat portions, or be inclined so as to run diagonally between the two flat portions. Each of the two flat portions may be connected to the web via a rounded corner.

[0050] In the present disclosure, the term "corner" is used to describe a region of a profile, as seen in cross section perpendicular to the longitudinal extension of the profile, where two profile portions extending in different directions meet so as to be directly connected to each other. As is well known to a person skilled in the art, such a corner may typically be a rounded corner and thus have a radius of curvature. Moreover, certain embodiments of the herein described beam assembly comprises a profile in which two profile portions (such as two leg portions) extending in different directions are connected via a "curved connection portion". Such a curved connection portion is here considered as a separate portion of the profile cross section, which means that the two profile portions are not directly connected to each other when a curved connection portion is arranged therebetween. A curved connection portion is in the present disclosure considered to be distinguished from a rounded corner connecting two profile portions (e.g., two leg portions) by having a longer extension, which in turn is a result of a larger radius of curvature compared to a rounded corner. More specifically, the radius of curvature of a curved connection portion is at least 5 times (often at least 7 times) the wall thickness of the thinnest profile portion (e.g., the thinnest leg portion) of the profile portions connected via the curved connection portion. In contrast, when the radius of curvature where two portions of a profile, extending in different directions, meet is smaller than 5 times the wall thickness of the thinnest of said two profile portions, the two profile portions (e.g., two leg portions) are considered to meet at a corner.

[0051] The beam assembly as described herein has primarily been developed for a front underrun protection system. In particular, it has been developed for a front underrun protection system of a vehicle, such as a heavy-duty vehicle or a medium-duty vehicle. However, the herein described beam assembly may also advantageously be used in a rear underrun protection system, or even in a side underrun protection system, of such a vehicle.

[0052] The beam assembly according to the present disclosure has, as seen in relation to its orientation when arranged in a vehicle, an upper side, an underside, and outward side, and an inward side. The beam assembly comprises a plurality of open steel profiles. Said plurality of open steel profiles comprises at least a first profile, a second profile, and a third profile. Each of the first, second, and third profiles extend longitudinally in the longitudinal direction of the beam assembly. The shapes of the first profile, the second profile, and the third profile, respectively, will in the following be described with reference to their respective cross section, perpendicular to the longitudinal extension of the respective profile. It should here be recognized that the cross sections of the first, second and third profiles may be seen as taken in a common plane, perpendicular to the longitudinal direction of the beam assembly. Thus, the cross sections of the first profile, the second profile, and the third profile, may alternatively be described as cross sections thereof in a common plane perpendicular to the longitudinal direction of the beam assembly. Said cross section of the beam assembly may for example be taken midway along its longitudinal direction, but is not limited thereto. The cross sections of the first, second, and third profiles may for example be substantially equal along their entire longitudinal extension between a first mounting region and a second mounting region of the beam assembly, each of said first and second mounting regions being configured for mounting of a support structure and / or an energy absorption member (e.g. a crash box or the like) to the beam assembly.

[0053] As previously mentioned, an open steel profile comprises at least two free ends when seen in cross section perpendicular to its longitudinal extension. Thus, each of the first profile, the second profile, and the third profile of the herein described beam assembly has a first open end and a second open end. Each of said open ends are formed by a corresponding open end portion of the profile. The first profile, the second profile, and the third profile need not comprise further free ends. In other words, each of the first profile, the second profile, and the third profile may comprise only two free ends when seen in the cross section perpendicular to their respective longitudinal extension. The first profile has a cross section, perpendicular to its longitudinal extension, comprising, or consisting of, a first leg portion and a second leg portion. The first and second leg portions may, or may not, be directly connected to each other. In case the first and second leg portions are directly connected to each other, they may suitably be connected with a rounded corner. In case cross section of the first profile not merely consists of the first leg portion and the second leg portion, the cross section of the first profile may further comprise a web portion or a curved connecting portion connecting the first leg portion with the second leg portion. Such a web portion may increase the shearing strength of the first profile and thereby contribute to increased stiffness of the beam assembly. A curved connection portion may also contribute to increased shearing strength of the beam assembly, albeit to a lower extent, and may further more reduce the risk of crack formation compared to if the first and second leg portions are directly connected. Alternatively, or additionally, the cross section of the first profile may comprise a curved stiffening portion connected to the second leg portion. Such a curved stiffening portion may be arranged between the first leg portion and the second leg portion, or be arranged to interrupt the second leg portion along its extension such that the second leg portion is divided into two parts connected by the curved stiffening portion. The first leg portion and the second leg portion of the first profile may be arranged perpendicular to each other, or may be angled relative each other with an obtuse angle. The first leg portion is arranged so as to form the outward side of the beam assembly, whereas the second leg portion is arranged so as to form the underside of the beam assembly.

[0054] The second profile has a cross section, perpendicular to its longitudinal extension, comprising a third leg portion and a fourth leg portion. The third leg portion of the second profile is arranged at an angle of from 75° to 105° relative to the first leg portion of the first profile. The fact that the third leg portion is arranged at such an angle relative to the first leg portion, which is arranged to form the outward side of the beam assembly and thus facing the impact in case of a collision, results in the second profile with its third leg portion acting as a reinforcement and thereby reducing the risk of the beam assembly collapsing as a result of the impact. Suitably, the third leg portion of the second profile may arranged at an angle of from 80° to 100° relative to the first leg portion of the first profile. The fourth leg portion of the second profile is arranged to form at least part of the inward side of the beam assembly. The third and fourth leg portions of the second profile may, or may not, be directly connected to each other. In case the third and fourth leg portions are directly connected to each other, they may suitably be connected with a rounded corner. In case the third and fourth leg portions are not directly connected to each other, they may be connected via an intermediate portion. The cross section of the second profile also comprises a first flange portion extending from the third leg portion. The first flange portion may typically extend from an end of the third leg portion opposing the end of the third leg portion facing towards the fourth leg portion. Moreover, the cross section of the second profile comprises a second flange portion extending from the fourth leg portion. Each of the first and second flange portions of the second profile may be regarded as forming a respective free end portion of the second profile and serve the purpose of allowing attachment of the second profile to the first profile of the beam assembly. The first flange portion of the second profile is either attached to the first leg portion of the first profile, or alternatively to the web portion (if present) of the first profile. It should here be noted that even if the first profile comprises the optional web portion, the first flange portion need not be attached to said web portion but may be attached to the first leg potion of the first profile. The second flange portion of the second profile is attached to the second leg portion of the first profile.

[0055] The third profile has a cross section, perpendicular to its longitudinal extension comprising a fifth leg portion arranged to form the upper side of the beam assembly. The third profile has a cross section further comprising a first free end portion, said first free end portion formed of a third flange portion extending from the fifth leg portion, and a second free end portion. The second free end portion may either be formed of a sixth leg portion of the third profile, or by a fourth flange portion extending from said sixth leg portion. The sixth leg portion may suitably be directly connected to the fifth leg portion. Moreover, the fifth leg portion and the sixth leg portion may be arranged perpendicular to, or with an obtuse angle relative to, each other. The third profile is, at its first free end portion (i.e. the third flange portion), attached to the first leg portion of the first profile. It should here be noted that the position at which the first free end of the third profile is attached to the first profile is distanced from the position at which the second profile (more specifically, the third flange portion of the second profile) is attached to the first profile. Moreover, the third profile is, at its second free end portion, attached to the fourth leg portion of the second profile or alternatively to the intermediate portion of the second profile (if said intermediate portion is present). In other words, the first free end of the third profile is attached to the first profile whereas the second free end of the third profile is attached to the second profile of the beam assembly. Thus, in contrast to the second profile of the beam assembly, the third profile is not attached at both its free end to the same other profile of the beam assembly.

[0056] In view of the foregoing, it may be realized that, at any point of attachment of the above discussed three profiles of the beam assembly to another one of the three profiles, only two of the profiles are attached to each other. Described differently, the cross section of the beam assembly does not comprise any point at which each of the first profile, the second profile, and the third profile are all attached to each other. Therefore, in case one of the attachments of the profiles within the beam assembly would be broken or otherwise fail as a result of impact during a possible collision of a vehicle comprising the beam assembly, the beam assembly would still hold together.

[0057] Each of the first profile, the second profile and the third profile of the herein described beam assembly may suitably have a wall thickness of from 1 mm to 5 mm, preferably from 2 mm to 4 mm (including the end values).

[0058] Moreover, each of the first profile, the second profile and the third profile of the herein described beam assembly may suitably be made of press-hardened steel (also called press hardening steel, and typically abbreviated PHS), such as press-hardened boron steel. Press-hardened steels are frequently used in the automotive industry due to their excellent energy absorption and deformation characteristics in the event of a crash. Press-hardened steels can achieve very high tensile strengths, often exceeding 1500 MPa. This in turn allows for production of thinner, and thus lighter, profiles without sacrificing structural integrity. Moreover, such steels have the advantage of being able to form into complex shapes, which makes them suitable for production of the profiles of the herein describe beam assembly. The press hardening process involves heating a steel blank to an austenitizing temperature (typically 900-1000 °C) to achieve an austenitic microstructure. The austenitic microstructure makes the steel more ductile and formable. Thereafter, the steel blank is transferred to a press, where it is formed (pressed) to the desired shape (here the shape of the respective profile). Said forming step is performed while the steel is still hot and having an austenitic microstructure. After the forming step, the steel is quenched while remaining in the press. The quenching is performed such as to transform the austenitic microstructure to martensite, which is a hard and strong phase giving the steel its intended high-strength properties.

[0059] Attachment of the first profile, the second profile, and third profile of the beam assembly to each other may be made through any previously known method therefore, including gluing, welding or through usage of various forms of fastening means (i.e. fasteners). Suitably, welding may be used for attaching the profiles of the beam assembly to each other.

[0060] Figure 1 schematically illustrates a side view of an example of a vehicle 1, here illustrated as a distribution truck. The vehicle 1 has a longitudinal axis A. The primary direction of travel of the vehicle 1, which is parallel with the vehicle's longitudinal axis A, is in the figure illustrated by arrow F. The vehicle 1 has a front side 2 and a rear side 3, between which two lateral sides of the vehicle 1 extend. The vehicle 1 comprises a chassis 4. The chassis 4 may typically comprise two side frames (only a first side frame 4a of the two side frames being shown) extending longitudinally on opposite sides of the longitudinal axis A. Said two side frames may typically be connected to each other by a plurality of transversal frames (not shown).

[0061] The vehicle 1 further comprises a front underrun protection system 5, which is mounted to the chassis 4. The front underrun protection system 5 comprises a horizontally arranged front underrun beam 6a which extends along the front side 2 of the vehicle. The front underrun beam 6a is intended to prevent underrun of smaller vehicles in case of a collision with the vehicle 1. Therefore, the front underrun beam 6a should be strong enough to absorb and distribute impact forces while preventing smaller from sliding underneath the vehicle 1. The front underrun beam 6a may also be intended to protect other constituent components of the vehicle 1 which may be sensitive to impact, in particular such constituent components which are critical to safety in operation of the vehicle 1 (e.g., a steering system, a brake system, etc. ). The front underrun beam 6a is supported by a support structure 6b of the front underrun protection system 5. The support structure 6b is in turn mounted to the chassis 4.

[0062] The exemplified vehicle 1 further comprises a rear underrun protection system 7, which is also mounted to the chassis 4. The rear underrun protection system 7 comprises a rear underrun beam 8a arranged horizontally and extending along the rear side 3 of the vehicle 1. The rear underrun beam 8a is supported by support structure 8b of the rear underrun protection system 7. Like the front underrun beam 6a, the rear underrun beam 8b is intended to prevent smaller vehicles from sliding underneath the vehicle 1 in case of a collision.

[0063] Whereas the rear underrun protection system 7 may often be visible to a person looking at the vehicle 1, the front underrun protection system 5 may typically be arranged inwardly of parts of the exterior surface of the vehicle 1 and thus hidden to a person looking at the vehicle 1. Such parts of the exterior surface of the vehicle are in the figure illustrated with dotted lines to enable showing the front underrun protection system 5. Although not shown in the figure, the vehicle 1 may further comprise one or more side underrun protection systems arranged along the respective lateral sides of the vehicle 1.

[0064] Figure 2 schematically illustrates a perspective view of a first exemplifying embodiment of an underrun protection system 10 according to the present disclosure. The underrun protection system 10 according to the first exemplifying embodiment is a front underrun protection system, and is suitable for use in a medium-duty or heavy-duty vehicle. The underrun protection system 10 may for example be arranged in the vehicle 1 shown in Figure 1 in place of the schematically illustrated underrun protection system 5.

[0065] The underrun protection system 10 shown in Figure 2 comprises a pair of support brackets 12 configured to allow mounting of the underrun protection system 10 to a chassis of a vehicle (compare with chassis 4 in Figure 1). More specifically, each support bracket 12 may be mounted to a respective side frame of the chassis of a vehicle. The support brackets 12 are in turn attached to a crossbeam 13. The crossbeam 13 is in turn arranged inwardly of a beam assembly 20 configured to serve as a protection against smaller vehicles being dragged in under a vehicle 1, comprising the underrun protection system 10, in case of a collision. The support brackets 12 and the crossbeam 13 may be regarded to jointly form a support structure 14 configured to support the beam assembly 20 relative to a chassis of the vehicle when the underrun protection system 10 is arranged in said vehicle.

[0066] Moreover, the underrun protection system 10 comprises a pair of energy absorption members 15 interposed between the beam assembly 20 and the crossbeam 13. The beam assembly comprises a first mounting region 20a and a second mounting region 20b, each configured for mounting to one of the energy absorption members 15. The first and second mounting regions 20a, 20b are separated from each other in the longitudinal direction L of the beam assembly 20. Typically, the first and second mounting regions 20a, 20b are arranged at equal distances from a longitudinal midpoint of the beam assembly 20. Each energy absorption member 15 may be in the form of a so called crash box or crash tube. The energy absorption members 15 are configured to absorb some of the kinetic energy during a collision through a controlled deformation of the energy absorption members 15, usually through folding to a wavy structure along an axial direction of the respective energy absorption member 15. The support brackets 12 support the beam assembly 20 via the crossbeam 13 and the energy absorption members 15 when the underrun protection system is arranged in the vehicle.

[0067] When the illustrated underrun protection system 10 is arranged in the vehicle, the beam assembly 20 may typically extend longitudinally substantially along the entire width of the vehicle. In other words, the beam assembly 20 may have a length substantially corresponding to the width of the vehicle in which the underrun protection system is arranged. The longitudinal direction of the beam assembly 20 is in the figure represented by double arrow L. The beam assembly 20 has, as seen in relation to its orientation when arranged in the vehicle, an upper side 21, an underside 22 (not visible in the illustrated perspective view), an outward side 23 and an inward side 24 (not visible in the illustrated perspective view). The outward side 23 is configured to meet the impact in case of a collision. In view of the underrun protection system 10 according to the first exemplifying embodiment being a front underrun protection system, the outward side 23 may alternatively be described as a front side of the beam assembly 20.

[0068] The beam assembly 20 may, as shown in the figure, be composed of a substantially straight beam assembly mid-section 26 and two curved side beam members 27, 28 attached to the substantially straight beam assembly section 26 at its respective longitudinal ends. Alternatively, the beam assembly 20 may comprise two curved longitudinal ends integrally formed with the mid-section 26. At least the mid-section 26 of the beam assembly 20 may have a cross section, perpendicular to its longitudinal direction L, according to any one of the exemplifying embodiments described below.

[0069] It should here be noted that the underrun protection system according to the present disclosure is not limited to the underrun protection system 10 illustrated in Figure 2, but encompasses any underrun protection system (for a vehicle) which comprises the herein described beam assembly 20. Thus, the underrun protection system according to the present disclosure e.g., need not comprise the energy absorption members 15. Furthermore, the underrun protection system need not be a front underrun protection system, but may alternatively be a rear underrun protection system (or even a side underrun protection system, if desired).

[0070] Cross-sectional views of various exemplifying embodiments, as will be described in more detail below, of the herein described beam assembly 20 are shown in Figures 3-8. In each of said figures, the cross-sectional view is taken perpendicular to the longitudinal direction (compare with double arrow L in Figure 2) of the herein described beam assembly 20. The cross-sectional views may for example be regarded as taken midway along the longitudinal direction of the beam assembly. Alternatively, the cross-sectional view may be regarded as taken at any other point along the longitudinal direction of the beam assembly between two mounting regions of the beam assembly (compare with mounting regions 20a, 20b shown in Figure 2), each such mounting region being configured for mounting of a support structure and / or an energy absorbing member to the beam assembly 20. Each of the exemplifying embodiments of the beam assembly may be used in an underrun protection system for a vehicle, such as the exemplified underrun protection system shown in Figure 2. Moreover, in each of the exemplifying embodiments shown in Figures 3-8, the beam assembly 20 comprises a first profile 30, a second profile 40, and a third profile 50. Each of the first profile 30, the second profile 40, and the third profile 50 constitutes an open steel profile. Moreover, each of the first profile 30, the second profile 40, and the third profile 50 extends longitudinally in the longitudinal direction of the beam assembly. Thus, in view of the Figures 3-8 showing a cross- sectional view the beam assembly as described above, the figures also show a cross section of each of the profiles, said cross section being perpendicular to the longitudinal extension of the respective profiles.

[0071] Figure 3 illustrates a cross-sectional view of a first exemplifying embodiment of the herein described beam assembly 20. The beam assembly 20 comprises a plurality of open steel profiles, each extending longitudinally in the longitudinal direction of the beam assembly 20. Thus, the plurality of open steel profiles are, in the figure, shown in a cross-section perpendicular to their respective longitudinal extension as previously mentioned. The plurality of open steel profiles comprises a first profile 30, a second profile 40, and a third profile 50. The second profile 40 is arranged between the first profile 30 and the third profile 50.

[0072] The first profile 30 has a cross section comprising a first leg portion and a second leg portion 32. The first leg portion 31 extends in a first plane Pl whereas the second the second leg portion 32 extends in a second plane P2. The second plane P2 is angled relative to the first plane Pl with an angle p . In the shown exemplified embodiment, the first and second leg portions 31, 32 are arranged perpendicular to each other, and the angle is thus a straight angle. The first and second leg portions 31, 32 are directly connected to each other, and the corner 39 where said leg portions 31, 32 meet may suitably be rounded to reduce potential stress concentrations. Thus, according to the first exemplifying embodiment of the beam assembly 20, the first profile 30 has a L-shaped profile cross section. It should however be noted that the first and second leg portions 31, 32 need not necessarily be arranged perpendicular to each other and that the angle p may alternatively be an obtuse angle (compare exemplifying embodiment shown in with Figure 7).

[0073] The first leg portion 31 of the first profile 30 is arranged to form an outward side 23 of the beam assembly. In other words, the first leg portion 31 forms the surface of the beam assembly 20 which is intended to face impact in case of a collision when the underrun protection system comprising the beam assembly is arranged in a vehicle. The second leg portion 32 of the first profile is arranged to form the underside of the beam assembly, as seen in relation to its orientation when arranged in the vehicle. The second profile 40 of the beam assembly 20 has a cross section comprising a third leg portion 41 and a fourth leg portion 42. The third and fourth leg portions 41, 42 are directly connected to each other, and the corner 49 where the third and fourth leg portions 41, 42 meet may suitably be rounded as shown in the figure. As seen in relation to the orientation when the beam assembly 20 is arranged in a vehicle, the fourth leg portion 42 is arranged to form at least part of the inward side 24 of the beam assembly 20. The third and fourth leg portions 41, 42 may be arranged to extend substantially perpendicular to each other, as shown in the figure. It should however be noted that the third and fourth leg portions 41, 42 need not be arranged perpendicular to each other, but could for example be arranged at with an obtuse angle relative each other.

[0074] The second profile 40 further comprises a first flange portion 43 extending from the third leg portion 41. More specifically, the first flange portion 43 extend from the third leg portion 41 at an end of the first leg portion 41 opposing the end where the third leg portion 41 is connected to the fourth leg portion 42. Moreover, the second profile 40 comprises a second flange portion 44 extending from the fourth leg portion 42. The second flange portion 44 extends from an end of fourth leg portion 42 opposing the end of the fourth leg portion 42 being connected to the third leg portion 41. The primary purpose of the first flange portion 43 and the second flange portion 44, respectively, is to allow easy attachment of the second profile 40 (at free ends thereof) to the first profile 30. Such an attachment may be made by welding, gluing, or fasteners as known in the art without departing from the present disclosure.

[0075] As previously mentioned, the third and fourth leg portions 41, 42 may be arranged substantially perpendicular to each other. In case the third and fourth leg portions 41, 42 are arranged perpendicular to each other, the third and fourth leg portions 41, 42 may be described as together forming a L-shaped profile cross section. Moreover, the second profile 40 may, as a whole, be described as a flanged L-shaped profile when seen in cross section when the third and fourth leg portions 41, 42 are perpendicular to each other.

[0076] The first flange portion 43 of the second profile 40 is attached to the first leg portion 31 of the first profile 30. Moreover, the second flange portion 44 of the second profile 40 is attached to the second leg portion 32 of the first profile 30. Furthermore, the third leg portion 41 of the second profile 40 extends in a third plane P3 which is angled relative to the first plane Pl, in which the first leg portion 31 of the first profile 30 extends, with an angle a. According to the illustrated exemplifying embodiment, the third leg portion 41 of the second profile 40 extends perpendicular to the first leg portion 31 of the first profile 30, and the angle a is thus a straight angle. However, angle a may be varied from 75° to 105° (including the end values of the range).

[0077] The third profile 50 of the beam assembly 20 according to the first exemplifying embodiment has a cross section comprising a fifth leg portion 51 and a sixth leg portion 52. The sixth leg portion 52 may be arranged to extend perpendicular to the fifth leg portion 51 as shown in the figure. The fifth leg portion 51 and the sixth leg portion 52 are directly connected to each other, preferably with a rounded corner 59 where the leg portions 51, 52 meet. The fifth leg portion 51 is arranged to form the upper side of the beam assembly 20 as seen in relation to the orientation of the beam assembly 20 when arranged in a vehicle. The sixth leg portion 52 is arranged to form part of the inward side 24 of the beam assembly 20.

[0078] Moreover, the third profile 50 comprises a first free end portion 50a, here formed by a third flange portion 53 extending from the fifth leg portion 51 at an end thereof opposing the end connected to the sixth leg portion 52. The third profile 50 further comprises a second free end portion 50b, which is part of the sixth leg portion 52. The third profile 50 of the first exemplifying embodiment of the beam assembly may be described as a Z-profile in which the fifth leg portion 51 constitutes a web of said Z-profile. As evident from the figure, such a Z-profile would be considered to be a so called unequal Z-profile in view of the sixth leg portion 52 being considerably longer than the third flange portion 53.

[0079] The third profile 50 is, at its first free end 50a, attached to the first leg portion 31 of the first profile 30. Moreover, the third profile is, at its second free end 50b, attached to fourth leg portion 42 of the second profile 40. The attachment of the third profile 50, at its free ends 50a, 50b, to the first profile 30 and the second profile 40, respectively, may be made by welding, gluing, or fasteners as known in the art without departing from the present disclosure.

[0080] Figure 4 illustrates a cross-sectional view of a second exemplifying embodiment of the herein described beam assembly 20. The second exemplifying embodiment corresponds to the exemplifying embodiment shown in Figure 3, except that the third profile 50 has a different configuration.

[0081] The third profile 50 of the beam assembly 20 according to the second exemplifying embodiment has a cross section in which, in contrast to the exemplifying embodiment shown in Figure 3, the fifth leg portion 51 and the sixth leg portion 52 are arranged to extend relative each other with an obtuse angle y. Moreover, in addition to the fifth leg portion 51, the sixth leg portion 52 and the third flange portion 53, the third profile 50 comprises a fourth flange portion 54. Said forth flange portion 54 extends from an end of the sixth leg portion 52 opposite to the end where the sixth leg portion 52 meets the fifth leg portion 51. As shown in the figure, the fourth flange portion 54 is arranged to form a part of the inward side 24 of the beam assembly 20 as seen in relation to the orientation of the beam assembly 20 when arranged in a vehicle.

[0082] In the second exemplifying embodiment, the second free end 50b of the third profile 50 is formed at the fourth flange portion 54. In other words, the second free end 50b of the third profile 50 is formed of the fourth flange portion 54 extending from the sixth leg portion 52. The third profile 50 is attached at its second free end 50b to the fourth leg portion 42 of the second profile 40. Moreover, the third profile 50 is, at its first free end 50a, attached to the first leg portion 31 of the first profile 30. Thus, in contrast to the exemplifying embodiment shown in Figure 3, the sixth leg portion 52 of the third profile 50 is not directly attached to the second profile 40.

[0083] The alternative configuration of the third profile 50 according to the second exemplifying embodiment, as shown in Figure 4, of the beam assembly 20 may e.g., increase the stiffness of the beam assembly compared to the first exemplifying embodiment thereof, as shown in Figure 3.

[0084] Figure 5 illustrates a cross-sectional view of a third exemplifying embodiment of the herein described beam assembly 20. The third exemplifying embodiment corresponds to the second exemplifying embodiment, as shown in Figure 4, except that the first profile 30 has a different configuration.

[0085] Like in the second exemplifying embodiment of the beam assembly 20, the first profile 30 has a cross section comprising a first leg portion 31 and a second leg portion 32. The first leg portion 31 extends in a first plane Pl whereas the second the second leg portion 32 extends in a second plane P2. The second plane P2 is angled relative to the first plane Pl with an angle p . The first and second leg portions 31, 32 may be arranged perpendicular to each other as shown in the figure, in which case the angle is a straight angle. The angle p between the planes Pl and P2 may alternatively be an obtuse angle.

[0086] However, in contrast to in the second exemplifying embodiment of the beam assembly 20, the first leg portion 31 of the first profile 30 is not directly connected to the second leg portion 32. Instead, the first leg portion 31 and the second leg portion 32 are connected by a web portion 31. In other words, the first profile 30 has a cross section, perpendicular to its longitudinal extension, comprising a web portion 33 connecting the first and second leg portions 31, 32. The web portion 33 may be a straight web portion 33, as shown in the figure, which has an angled extension relative to each of the planes Pl and P2 when seen in the cross sectional view perpendicular to the longitudinal direction of the beam assembly. The web portion 33 may for extend with an angle of from 30° to 60° relative to the extension of the first leg portion 31 (and thus also plane Pl), as seen in the cross sectional view. The web portion 33 contributes to increased shearing strength of the first profile 30 compared to if the first and second leg portions 31, 32 are directly connected to each other. Thus, the alternative configuration of the first profile 30 according to the third exemplifying embodiment of the beam assembly, as shown in Figure 5, may further increase stiffness of the beam assembly 20 compared to the exemplifying embodiments shown in Figures 3 and 4.

[0087] Although the third profile 50 according to the third exemplifying embodiment has a configuration corresponding to the configuration of the third profile 50 of the exemplifying embodiment shown in Figure 4, it should be noted that the third profile 50 of the third exemplifying embodiment may alternatively have a configuration corresponding to the third profile 50 shown in Figure 3. In other words, the third profile 50 of the beam assembly according to the third exemplifying embodiment may be modified to consist of a fifth leg portion 51 arranged perpendicular to a sixth leg portion 52 and having a third flange portion 53 extending from the fifth leg portion at the end thereof opposing the end connected to the sixth leg portion 52.

[0088] Figure 6 illustrates a cross-sectional view of a fourth exemplifying embodiment of the herein described beam assembly 20. The fourth exemplifying embodiment is similar to the third exemplifying embodiment shown in Figure 5. For example, the first profile 30 has a cross section comprising a first leg portion 31, a second leg portion 32, and a web portion 33 that connects the first and second leg portions 31, 32. Moreover, the third profile 50 has a cross section comprising a fifth leg portion 50, a sixth leg portion, a third flange portion 53 and a fourth flange portion 54. The third flange portion 54 of the third profile 50 is attached to the first leg portion 31 of the first profile 30, and the fourth flange portion 54 of the second profile 50 is attached to the fourth leg portion 42 of the second profile 40. Furthermore, the second flange portion 44 of the second profile 40 is attached to the second leg portion 32 of the first profile 30. However, in contrast to the third exemplifying embodiment, the first flange portion 43 of the second profile 40 is not attached to the first leg portion 31 of the first profile 30. Instead, the first flange portion 43 of the second profile 40 is attached to the web portion 33 of the first profile 30.

[0089] It should here be noted that, although the second profile 40 is, at the first flange portion 43, is attached to the web portion 33 of the first profile 30, the third leg portion 41 of the second profile 40 is still arranged at an angle a of from 75° to 105° (including the end values of the range) relative to the first leg portion 31 of the first profile 30. In other words, the third leg portion 41 of the second profile 40 extends in a third plane P3 which is angled relative to the first plane Pl, in which the first leg portion 31 of the first profile 30 extends, with an angle a of from 75° to 105°.

[0090] Figure 7 illustrates a cross-sectional view of a fifth exemplifying embodiment of the herein described beam assembly 20. The fifth exemplifying embodiment essentially corresponds to the first exemplifying embodiment of the beam assembly, as illustrated in Figure 3, except that the second profile 40 has a slightly different configuration as will be further described below. Moreover, the first and second leg portions 31, 32 of the first profile 30 are not perpendicular, but the angle p between the planes Pl and P2 is an obtuse angle. In other words, the second leg portion 32 of the first profile 30 is arranged with an obtuse angle relative to the first leg portion 31 of the first profile 30. Furthermore, the first and second leg portions 31, 32 of the first profile are not directly connected to each other at a corner (compare with corner 39 in Figure 3), but connected via a curved connection portion 34. Such a curved connection portion 34 may contribute to increased shearing strength of the beam assembly and / or increased stiffness. Moreover, in case the first profile 30 is made through cold forming, the curved connection portion 34 may also reduce the risk for possible residual stress concentrations which could otherwise increase the risk of crack formation in case of a collision. As previously mentioned, a curved connection portion is in the present disclosure considered to be distinguished from a rounded corner connecting two leg portions by having a longer extension, which in turn is a result of a larger radius of curvature. More specifically, the radius of curvature of a connection portion is at least 5 times (often at least 7 times) the wall thickness of the thinnest leg portion of the first and second leg portions 31,32 of the first profile 30. When the radius of curvature where two leg portions of a profile meet is smaller than 5 times the wall thickness of the thinnest of said leg portions, the leg portions are instead considered to meet at a corner.

[0091] Like in the previously described exemplifying embodiments of the beam assembly, the second profile 40 of the fifth exemplifying embodiment has a cross section, perpendicular to its longitudinal extension, comprising a third leg portion 41, a fourth leg portion 42, a first flange portion 43 and a second flange portion 44. The third leg portion 41 is arranged at an angle a of 75-105° relative to the first leg portion 31 of the first profile 30. Moreover, the first flange portion 43 extends from the third leg portion and is attached to the first leg portion 31 of the first profile 30. The second flange portion 44 extends from the fourth leg portion 42 and is attached to the second leg portion 32 of the first profile. However, in contrast to previously described exemplifying embodiments, the third and fourth leg portions 41, 42 of the second profile 40 are not directly connected to each other. Moreover, the third and fourth leg portions 41, 42 do not form a L-shaped profile section. Instead, the second profile 40 comprises an intermediate portion 48 arranged to connect the third leg portion 41 with the fourth leg portion 42. As shown in the figure, the intermediate portion 48 may be arranged to primarily extend in a plane P5 which is substantially parallel to a plane P4 in which the fourth leg portion 42 extends, but is not limited thereto. The intermediate portion 48 may thus be described to be displaced with regard to the plane P4 in which the fourth leg portion 42 extends. The plane P5 is closer to the plane Pl in which the first leg portion 31 of the first profile 30 extends than what plane P4 is. Additionally, or alternatively, the intermediate portion 48 may be arranged to extend substantially perpendicular to the third leg portion 41 of the second profile 40. By means of the intermediate portion 48, it may be easier to position the third profile 50 relative to the second profile 40 during production of the beam assembly 20. The intermediate portion 48 may further allow the sixth leg portion 52 of the third profile 50 to be arranged substantially flush with the forth leg portion 42 of the second profile 40, if desired, to thereby form a more coherent inward side 24 of the beam assembly.

[0092] In accordance with the fifth exemplifying embodiment of the beam assembly 20, the third profile 50 is, at its second free end portion 50b, attached to the intermediate portion 48 of second profile 40. Moreover, the third profile 50 is, at its first free end 50a, attached to the first leg portion 31 of the first profile 30.

[0093] It should here be noted that, although not illustrated in any figure, the beam assembly 20 according to the first exemplifying embodiment as shown in Figure 3 may naturally be modified such that the first profile 30 comprises a curved connection portion 34, connecting the first and second leg portions 31, 32, in the same way as shown in Figure 7. This would correspond to a modification of the beam assembly 20 shown in Figure 7 such that the second profile 40 has a cross section as described with reference to Figure 3.

[0094] The beam assembly 20 according to the fifth exemplifying embodiment, as shown in Figure 7, may alternatively or additionally be modified such that the third profile 50 has a cross section as described with reference to the exemplifying embodiment shown in Figure 4. In other words, the fifth exemplifying embodiment may be modified to comprise a third profile 50 which comprises a fourth flange portion 54 extending from the sixth leg portion 52 and in which the fifth leg portion 51 and the sixth leg portion 52 are arranged to extend relative each other with an obtuse angle y. In such a case, the third profile 50 is attached at its second free end 50b (which is formed by the fourth flange portion 54) to the fourth leg portion 42 of the second profile 40 (compare with Figure 8). Figure 8 illustrates a cross-sectional view of a sixth exemplifying embodiment of the herein described beam assembly 20. Like the previously described exemplifying embodiments, the beam assembly 20 shown in Figure 8 comprises a first profile 30, a second profile 40, and a third profile 50.

[0095] According to the sixth exemplifying embodiment, the first profile 30 has a cross section, perpendicular to its longitudinal extension, comprising a first leg portion 31 and a second leg portion 32. As seen in relation to the orientation of the beam assembly 20 when arranged in a vehicle, the first leg portion 31 is arranged to form an outward side 23 of the beam assembly 20 and the second leg portion 32 is arranged to form an underside of the beam assembly 20. The second leg portion 32 of the first profile 30 may be arranged with an obtuse angle p relative to the first leg portion 31 of the first profile 30 (compare with exemplifying embodiment shown in Figure 7). The first profile 30 has a cross section further comprising a curved connection portion 34. The curved connection portion 34 is interposed between the first and second leg portions 34. The first profile 30 has a cross section further comprising a curved stiffening portion 35 connected to the second leg portion 32 at an end of the second leg portion 32 facing towards the first leg portion 31. Thus, the first and second leg portion 31, 32 of the first profile are connected to each other via the curved connection portion 34 and the curved stiffening portion 35. As shown in the figure, the curved stiffening portion 35 may protrude upwards towards the second profile 40. The curved connection portion 34 and the curved stiffening portion 35 may be regarded as jointly forming a substantially S-shaped profile section of the first profile 30.

[0096] By means of such the curved stiffening portion 35, the stiffness of the beam assembly 20, if subjected to impact as a result of a collision of a vehicle comprising the beam assembly, may be further improved. The curved stiffening portion 35 may suitably extend longitudinally substantially along the full longitudinal extension of the first profile 30, but is not limited thereto.

[0097] The second profile 40 has a cross section, perpendicular to its longitudinal extension, as described above with regard to the exemplifying embodiment shown in Figure 7. The second profile 40 may however be modified to have a cross section as described above with reference to the exemplifying embodiment shown in Figure 3. In other words, the second profile 40 need not necessarily comprise the intermediate portion 48, but the third leg portion 41 of the second profile 40 may be directly connected to the fourth leg portion 42 of the second profile 40. The third profile 50 has a cross section, perpendicular to its longitudinal extension, as described above with refence to the exemplifying embodiment shown in Figure 4. The third profile 50 may however be modified to have a cross section as described above with reference to the exemplifying embodiment shown in Figure 3. In other words, the third profile 50 may be modified to a be a Z- profile in which the fifth leg portion 51 constitutes the web of the Z-profile.

[0098] As shown in Figure 8, the first flange portion 43 of the second profile 40 is attached to the first leg portion 31 of the first profile 30. The second flange portion 44 of the second profile is attached to the second leg portion 32 of the first profile 30. Moreover, the third profile 50 is, at its first free end portion 50a (which is formed by the third flange portion 53), attached to the first leg portion 31 of the first profile 30. The third profile 50 is, at its second free end portion 50b (which is formed by the fourth flange portion 54), attached to the intermediate portion 48 of the second profile 40. In case the second profile 40 does not comprise the intermediate portion 48, the third profile 50 is instead, at its second free end portion 50b, attached to the fourth leg portion 42 of the second profile 40. As evident from the above, the second free end portion 50b of the third profile may be formed either by the fourth flange portion 54 or, if the fourth flange portion 54 is not present, by the sixth leg portion 52 of the third profile 50.

[0099] It should here be noted that, although not illustrated in any figure, the beam assembly 20 according to any one of the exemplifying embodiments of Figure 3-7, may be modified such that the first profile 30 further comprises a curved stiffening portion 35, like shown in Figure 8. Such a curved stiffening portion 35 would in such a case be connected to an end of the second leg portion 32 facing towards the first leg portion 31, or alternatively be arranged to interrupt the second leg portion 32 along its extension in plane P2 such that the second leg portion 32 is divided into two parts connected by the curved stiffening portion 35. In other words, according to the latter alternative, the curved stiffening portion would be connected to each of the two parts of the second leg portion 32 of the first profile 30.

[0100] Figure 9 illustrates a perspective view of part of a first alternative embodiment of the second profile 40 of the herein described beam assembly. As shown in the figure, the third leg portion 41 of the second profile 40 comprises a plurality of through-holes 46 distributed along the longitudinal extension of the second profile 40. The through-holes 46 may for example have a circular or oval configuration, but are not limited thereto. The plurality of through-holes 46 contributes to increased stiffness through affecting the force distribution through the second profile 50 in case of a collision of a vehicle comprising the beam assembly. Moreover, the plurality of through-holes 46 may also contribute to decreased weight of the beam assembly and thus also of a vehicle comprising the beam assembly. To seek to reduce the weight of a vehicle is an important aspect in the automotive industry in order reduce total cost of operation of the vehicle. The alternative embodiment of the second profile 40, as shown in Figure 9, may be comprised in any one of the exemplifying embodiments as shown in Figures 3-6 of the herein described beam assembly. Correspondingly, the second profile 40 of any one of the exemplifying embodiments of the beam assembly 20 as shown in Figures 7-8 may have a third leg portion 41 comprising a plurality of through-holes 46 distributed along the longitudinal extension of the second profile 40 in the same way as shown in Figure 9. It should however be noted that the presence of a plurality of through- holes 46 in the third leg portion 41 of the second profile 40 of the herein described beam assembly is optional. Thus, the beam assembly according 20 to any one of the exemplifying embodiments shown in Figures 3-8 may alternatively comprise a second profile 40 which does not comprise the plurality of though-holes 46 illustrated in Figure 9. Omittance of the through-holes 46 may for example contribute to reduced manufacturing costs for the beam assembly.

Claims

CLAIMS1. A beam assembly (20) for an underrun protection system (10) of a vehicle (1), the beam assembly (20) having, as seen in relation to its orientation when arranged in the vehicle (1), an upper side (21), an underside (22), an outward side (23), and an inward side (24), the beam assembly (20) comprising a plurality of open steel profiles (30, 40, 50) extending longitudinally in a longitudinal direction (L) of the beam assembly (20), said plurality of open steel profiles (30, 40, 50) comprising a first profile (30), a second profile (40), and a third profile (50), wherein(a) the first profile (30) has a cross section, perpendicular to its longitudinal extension, comprising: a first leg portion (31) arranged to form the outward side (23) of the beam assembly (20), a second leg portion (32) arranged to form the underside (22) of the beam assembly (20), and optionally a web portion (33) connecting the first and second leg portions (31, 32);(b) the second profile (40) has a cross section, perpendicular to its longitudinal extension, comprising: a third leg portion (41) arranged at an angle (a) of 75-105° relative to the first leg portion (31) of the first profile (30), a fourth leg portion (42) arranged to form at least a part of the inward side (24) of the beam assembly (20), a first flange portion (43) extending from the third leg portion (41), the first flange portion (43) being attached to the first leg portion (31) or the optional web portion (33) of the first profile (30), a second flange portion (44) extending from the fourth leg portion (42), the second flange portion (44) being attached to the second leg portion (32) of the first profile (30), and optionally an intermediate portion (48) connecting the third leg portion (41) with the fourth leg portion (42); and(c) the third profile (50) has a cross section, perpendicular to its longitudinal extension, comprising:a fifth leg portion (51) arranged to form the upper side (21) of the beam assembly (20), and a first free end portion (50a) and a second free end portion (50b); wherein the third profile (50) is, at its first free end portion (50a), attached to the first leg portion (31) of the first profile (30), and, at its second free end portion (50b), attached to the fourth leg portion (42) of the second profile (40) or the optional intermediate portion (48) of the second profile (40).

2. The beam assembly (20) according to claim 1, wherein the second leg portion (32) of the first profile (30) is arranged perpendicular to, or with an obtuse angle (P) relative to, the first leg portion (31) of the first profile (30).

3. The beam assembly (20) according to any one of claims 1 or 2, wherein the second leg portion (32) of the first profile (30) is connected to the first leg portion (31) via a curved connection portion (34).

4. The beam assembly (20) according to any one of the preceding claims, wherein the third leg portion (41) and the fourth leg portion (42) of the second profile (40) together form a L- shaped profile section.

5. The beam assembly (20) according to any one of claims 1 to 3, wherein intermediate portion (48) of the second profile (40) extends in a plane (P5) that is substantially parallel to a plane (P4) in which the fourth leg portion (42) of the second profile (40) extends, and / or wherein the intermediate portion (48) is arranged substantially perpendicular to the third leg portion (41) of the second profile (40).

6. The beam assembly (20) according to any one of the preceding claims, wherein the third profile (50) has a cross section, perpendicular to its longitudinal extension, further comprising: a sixth leg portion (52) angled relative to the fifth leg portion (51), and wherein the second free end portion (50b) of the third profile is formed of a fourth flange portion (54) extending from the sixth leg portion (52).

7. The beam assembly (20) according to any one of claims 1 to 5, wherein the third profile (50) constitutes a Z-profile in which the fifth leg portion (51) constitutes a web of said Z-profile.

8. The beam assembly (20) according to any one of the preceding claims, wherein the third leg portion (41) of the second profile (40) comprises a plurality of through-holes (46) distributed along the longitudinal extension of the second profile (40).

9. The beam assembly (20) according to any one of the preceding claims, wherein the first profile (30) comprises a curved stiffening portion (35) protruding upwards towards the second profile (40), said curved stiffening portion (35) being connected to the second leg portion (32) of the first profile (30).

10. The beam assembly (20) according to any one of the preceding claims, further comprising a first mounting region (20a) and a second mounting region (20b), separated from each other in the longitudinal direction (L) of the beam assembly (20), each of the first and second mounting regions (20a, 20b) being configured for mounting of a support structure (14) and / or an energy absorbing member (15) of the underrun protection system (10), wherein each of the first, second, and third profiles (30, 40, 50) extends longitudinally at least between the first and second mounting regions (20a, 20b).

11. An underrun protection system (10) for a vehicle (1), the underrun protection system (10) comprising the beam assembly (20) according to any one of the preceding claims.

12. The underrun protection system (10) according to claim 11, wherein the underrun protection system (10) is a front underrun protection system.

13. The underrun protection system (10) according to any one of claims 11 or 12, further comprising a first and a second energy absorption member (15), each of the first and second energy absorption members (15) being attached to the beam assembly (20).

14. The underrun protection system (10) according to any one of claims 11 to 13, further comprising a support structure (14) configured to support the beam assembly (20) relative to a chassis (4) of the vehicle (1) when the underrun protection system (10) is arranged in the vehicle (1).

15. A vehicle (1) comprising the beam assembly (20) according to any one of claims 1 to 10.

16. The vehicle (1) according to claim 15, wherein the vehicle (1) is a medium-duty or a heavy- duty vehicle.

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