TECHNICAL FIELD

[0001] The disclosure relates to a vehicle frame assembly. In particular aspects, the disclosure relates to an energy-absorbing system of a vehicle frame assembly.

[0002] The disclosure can be applied in light, medium and heavy-duty vehicles, such as trucks, buses and construction equipment.

BACKGROUND

[0003] Electric vehicles such as battery electric vehicles (BEV) and fuel cell electric vehicles (FCEV) are equipped with an electric subassembly including electrical/electronic components for providing electrical power to the vehicle.

[0004] The electric subassembly should be protected in case of a collision, to preserve its integrity, and ensure safety. Moreover, as collision results in a deformation of the vehicle frame, protection of battery packs and/or hydrogen tanks is also at stake.

[0005] In addition, the front part of the vehicle frame has a high rigidity due to increasing requirements for safety, durability, and/or noise, vibration and harshness (NVH) characteristics. Therefore, in case of a collision (especially a frontal collision), a high amount of load may be transferred to the frame rails and should be dissipated to prevent damage to critical electric components.

SUMMARY

[0006] The disclosure may seek to provide an energy absorbing system of a vehicle frame assembly which efficiently protects (e.g., in case of collision) the electric subassembly secured thereto. The energy absorbing system may deform to dissipate energy and protect the electric subassembly.

[0007] By “energy-absorbing system” is meant a structure that can dissipate the kinetic energy resulting from a collision.

[0008] According to a first aspect, the disclosure relates to a vehicle frame assembly, comprising a frame having two rails extending in a longitudinal direction, and at least one cross-member coupling the rails and extending along a transverse direction, an electric subassembly comprising a sub-frame arranged between the rails, forward of the cross- member, the sub-frame being secured to each rail by at least one side mount, and an energyabsorbing system arranged between the two rails, between the sub-frame and the crossmember, and attached to at least one of the sub-frame and the cross-member, the energyabsorbing system extending in the longitudinal direction and being less stiff than the subframe and the cross-member to deform and absorb energy from a vehicular collision on the vehicle frame assembly.

[0009] The energy-absorbing system may be configured to deform and absorb part of the energy resulting from a frontal collision on the vehicle frame assembly.

[0010] The energy-absorbing system absorbs part of the whole amount of energy, thereby reducing the amount of energy absorbed by the frame and/or sub-frame of the electric assembly. As the energy-absorbing system is less stiff than the sub-frame of the electric assembly and the cross-member of the sub-frame, the energy absorbing system is the part of the vehicle frame assembly that is likely to undergo a significant proportion of the deformation, and thus to dissipate a significant portion of the energy by deformation.

[0011] In a vehicular collision, the energy-absorbing system may distribute impact load to the rear of the electric subassembly, reduce frame deformation, and/or stabilize movement of the electric subassembly after side mounts are ruptured from the rails. As a consequence of the reduction and/or control of frame deformation, the critical components which are mounted on the frame, such as the electric subassembly, battery packs and/or hydrogen tanks, are less impacted and therefore better protected. The disclosure may improve safety, even following a high-speed collision.

[0012] Arranging the energy-absorbing system rearward of the sub-frame and forward of the cross-member may have several advantages. Positioning of the energy-absorbing system results in little or no free space between the sub-frame and the cross-member, such that upon a frontal impact and rupturing of the side mounts, the forward movement of the frame is reduced resulting in less frame deformation and eventually less damage to components secured to the frame. In other words, the energy-absorbing system may absorb part of the energy, reduce frame deformation, and/or and/or control frame deformation, such by reducing forward displacement of the frame. In certain vehicles, the front part of the vehicle frame may not provide enough space for accommodating an energy-absorbing system with good performance.

[0013] In an example, in the area located between the sub-frame and the cross-member, there is arranged only the energy-absorbing system which may help prevent damage caused to the electric subassembly by stiffer parts from the rear. [0014] In an example, the energy-absorbing system is attached to both the sub-frame and the cross-member. The energy-absorbing system can thus join the sub-frame and the crossmember.

[0015] Alternatively, the energy-absorbing system can be attached to the sub-frame and not to the cross-member; or the energy-absorbing system can be attached to the crossmember and not to the sub-frame.

[0016] The energy-absorbing system can comprise a single device arranged between the sub-frame and the cross-member.

[0017] Alternatively, the energy-absorbing system comprises at least two devices adjacently arranged between the sub-frame and the cross-member. The energy-absorbing system can comprise at least two devices arranged in parallel between the sub-frame and the cross-member. These devices may be identical.

[0018] The energy-absorbing system may have a honeycomb inner structure.

[0019] The energy-absorbing system may comprise a chamber containing a compressible fluid.

[0020] The energy-absorbing system may comprise a hollow body having an axis substantially parallel to the longitudinal direction. For example, said hollow body can form a circular tube, or can include plates welded together along their longitudinal edges.

[0021] The energy-absorbing system may comprise a crash initiator. Said crash initiator can be stamped on said energy-absorbing system.

[0022] The energy-absorbing system can be made of at least one material included in the group comprising: steel, aluminium, high strength energy plastics, high energy absorbing materials such as fiber composites. The material may include foams and/or porous materials, which are typical high energy absorbing materials. Fiber composites, like carbon fibers, have relative higher stiffness, strength and lightweight compared to their steel counterpart.

[0023] The stiffness of the frame may be at least 550 MPa. The stiffness of the sub-frame may be at least 550 MPa. The stiffness of the energy-absorbing system may be comprised between 250 and 350 MPa.

[0024] The electric subassembly can comprise at least one fuel cell stack. This applies in particular to fuel cell electric vehicles (FCEV).

[0025] According to a second aspect, the disclosure relates to a vehicle, in particular an industrial vehicle, comprising a vehicle frame assembly as previously described. The energyabsorbing system can be located below a vehicle cab or just behind the cab. [0026] Further advantages and advantageous features of the disclosure are disclosed in the following description and in the dependent claims.

[0027] The above aspects, accompanying claims, and/or examples disclosed herein above and later below may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art.

[0028] Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein. There are also disclosed herein control units, computer readable media, and computer program products associated with the above discussed technical effects and corresponding advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] With reference to the appended drawings, below follows a more detailed description of aspects of the disclosure cited as examples.

[0030] FIG. 1 is a schematic perspective view of a vehicle according to an example of the disclosure, the vehicle including a frame, an electric subassembly and an energyabsorbing system;

[0031] FIG. 2 is a schematic and partial top view of a vehicle frame assembly including a frame, electric subassembly and energy-absorbing system, in a fuel cell electric vehicle;

[0032] FIG. 3 is a schematic and partial top view of a vehicle frame assembly including a frame, electric subassembly and energy-absorbing system, in a battery electric vehicle;

[0033] FIG. 4-6 show the deformation over time of the vehicle frame assembly of figure 2 following a frontal collision;

[0034] FIG. 7-9 are views similar to figures 4-6, respectively, for a vehicle frame assembly devoid of the energy-absorbing system according to the disclosure;

[0035] FIG. 10-12 are schematic and partial top views of a vehicle frame assembly according to different examples; and

[0036] FIG. 13 is a perspective view of an energy-absorbing system according to an example of the disclosure.

DETAILED DESCRIPTION [0037] Aspects set forth below represent the necessary information to enable those skilled in the art to practice the disclosure.

[0038] The disclosure may seek to provide an energy absorbing system of a vehicle frame assembly which efficiently protects (e.g., in case of collision) the electric subassembly secured thereto. The energy absorbing system may deform to dissipate energy and protect the electrica subassembly.

[0039] Figure 1 shows a vehicle 1 which comprises a cab 2 mounted on a frame 3 supported by front wheels 4 and rear wheels 5. The vehicle illustrated is a truck, but the disclosure can also apply to other vehicles, in particular industrial vehicles, such as buses or construction equipment. Z is defined as the vertical direction, X is defined as the longitudinal direction of the vehicle 1, and Y is defined as the transverse direction of the vehicle 1.

[0040] The frame 3 typically comprises two rails 6 which extend in the longitudinal direction X, as well as at least one cross member assembly 7 which extends in the transverse direction Y and which couples the rails 6. The frame 3 may be made of steel or cast iron. It can have a stiffness of at least 550 MPa.

[0041] A vehicle frame assembly 100 of the vehicle 1 comprises the frame 3, an electric subassembly 10 comprising a sub-frame 11 which is arranged between the rails 6, forward of the cross-member 7, and an energy-absorbing system 50 which is arranged between the subframe 11 and the cross-member 7, in a “crumple zone” 20, and which extends longitudinally. [0042] The electric subassembly 10 comprises electrical/electronic components 12 for operating the system that provides electrical power to the vehicle 1. In a fuel cell electric vehicle (FCEV), as shown in figure 2, said components 12 include fuel cell stacks. In a battery electric vehicle (BEV), as shown in figure 3, said components 12 can include a 24V system, an inverter, a converter, a heating unit, etc.

[0043] The sub-frame 11 of the electric subassembly 10 is secured to each rail 6 by at least one side mount 13. In the non-limiting illustrated example, the sub-frame 11 is secured to each rail 6 by two sides mounts 13, which can be located at the front and at the rear of the sub-frame 11. In certain examples, the sub-frame 11 can be fully or at least partially located under the cab 2. The sub-frame 11 may include two longitudinal beams coupled by a front beam and a rear beam, therefore forming at least one compartment for receiving one or more component 12. The sub-frame 11 may further include at least one cross-member arranged between the front beam and the rear beam, one compartment being formed between one beam and one cross-member of the sub-frame 11. The sub-frame 11 includes attachments for attaching the components 12. The sub-frame 11 may be made of steel or cast iron; it may have a stiffness of the sub-frame of at least 550 MPa. For example, the sub-frame 11 can have a strength equal or greater than the strength of the cross-member 7.

[0044] Any damage to electrical/electronic components 12 such as 24V system, inverter, converter, heating unit, etc., can lead to short circuit or overall functionality issue. In regards damage to fuel cell stacks, it can lead to hydrogen leakage. All this may pose safety risks. The electrical/electronic components 12 can be made of aluminium material and therefore, are soft in nature for crash performance, as compared to the surrounding components which are made of steel or cast iron, including the frame 3 and sub-frame 11.

[0045] The energy-absorbing system 50 is attached to at least one of the sub-frame 11 and the cross-member 7. In the example of figures 10-12, the energy-absorbing system 50 is shown as being attached to both the sub-frame 11 and the cross-member 7, which may lead to a high performance. However, in other examples, the energy-absorbing system can be attached to only one of the sub-frame or the cross-member 7. In the example of figures2-6, the energy-absorbing system 50 is attached only to the cross-member 7, but not to the subframe 11.

[0046] The parameters of the energy-absorbing system 50 can be determined according to the dimensions of the frame 3 and electric subassembly 10, and further depends on the available space. In an example, the length of the energy-absorbing system 50 - along longitudinal direction X - may be around 100-150 mm. The energy-absorbing system 50 is less stiff than the sub-frame 11 of the electric subassembly 10 and than the cross-member 7. In an exemple, the material of the energy-absorbing system 50 is less stiff than the sub-frame 11 and the cross-member 7. The material of the energy-absorbing system 50 may be at least one of steel, aluminium, high strength energy plastics, and/or high energy absorbing materials, such as fiber composites, foams and/or porous materials. For example, the energyabsorbing system 50 may be made of a low carbon or medium carbon steel with a yield strength in the range of 250-350 MPa.

[0047] According to the disclosure, the energy-absorbing system 50 is configured to deform and absorb part of the energy resulting from a collision on the vehicle frame assembly 100, for example a frontal collision.

[0048] More specifically, the energy-absorbing system 50 is configured to be compressed along the longitudinal direction X following a frontal crash, as can be seen in figures 4 to 6. In figure 4, the vehicle frame assembly 100 is shown at rest, before the frontal impact which is represented by arrows A. Then, the deformation begins. [0049] The cross-member 7 is preferably configured to hold the load coming from the front and directed rearward. It therefore provides a strong support to the energy-absorbing system 50 and allows the longitudinal compression thereof. The cross-member 7 is preferably configured not to be ruptured or buckled or detached from the rails 6 before the energyabsorbing system 50 is fully compressed. In an example, the cross-member 7 undergoes no or a very limited deformation.

[0050] As can be seen in figure 5, in an intermediate state, at least some of the side mounts 13 which join the sub-frame 11 of the electric subassembly 10 to the rails 6 are highly deformed or even broken due to the rearward movement of the sub-frame 11. As a result, the energy-absorbing system 50 has come into contact with the rear side of the sub-frame 11 and has begun to be compressed by said sub-frame 11 (mainly along the longitudinal direction X). The frontal collision further entails the rails 6 to be deformed by bending outwardly. [0051] In a final state, as shown in figure 6, the energy-absorbing system 50 is highly compressed, or even fully compressed, between the sub-frame 11 which has moved rearward over a fairly long distance, and the cross-member 7 which may not have moved nor been significantly deformed. The rails 6 are even more deformed, and can be bent at right angles. [0052] The simulations, illustrated in figures 4 to 6, indicate that, following a frontal collision, the sub-frame 11 of the electric subassembly 10 moves rearward substantially longitudinally and substantially keeps its original shape. Thus, the electrical/electronic components 12 are shielded from forces that may cause significant damage, and the safety consequences are greatly reduced or even avoided. The energy absorbing system 50 may also control the deformation in such a way that it is more even laterally. Thus, the energy absorbing system 50 facilitates the distribution of forces and energy between the rails 6 for a more controlled buckle.

[0053] Figures 7 to 9 are obtained through simulations for a conventional vehicle frame assembly 100, devoid of energy-absorbing system 50. Figures 7 to 9 correspond respectively to figures 4 to 6 and illustrate an improvement of the disclosure.

[0054] Indeed, soon after the frontal collision, as illustrated in figure 8, the sub-frame 11 of the electric subassembly 10 has already undergone a significant deformation and lost its original shape. The same is true for the rails 6. Then, in the final state (figure 9), the subframe 11 is greatly deformed, which may result in significant damage to the electrical/electronic components 12. The deformation of the rails may also be significant, which may jeopardize the safety of other equipment secured to the vehicle frame 3, such as batteries or hydrogen tanks. Furthermore, the sub-frame 11 may have been rotated or twisted with respect to its original substantially longitudinal arrangement. Consequently, edges or corners of the sub-frame 11 may have hit the rails 6, thus causing additional damages.

[0055] Arranging the energy-absorbing system 50 rearward of the electric subassembly 10 may help reducing the deformation of the vehicle frame 3 by limiting the forward displacement of said frame 3. Having the vehicle frame assembly 100 configured such that the crumple zone 20 is active (i.e. the compression of the energy-absorbing system 50 begins) after the side mounts 13 are broken may make overall impact stable in this critical zone.

[0056] In an example, as shown in figure 10, the energy-absorbing system 50 comprises two devices 51 adjacently arranged between the sub-frame 11 and the cross-member 7. The devices 51 may be substantially identical. The devices 51 may be arranged in parallel as shown in figure 10 or may converge towards each other as shown in figure 2. They may converge towards the front or towards the rear of the vehicle 1. Having two devices 51, and thus two attachment points of the energy-absorbing system 50 on the frame 3, may lead to a better performance and a better deformation control.

[0057] Alternatively, the energy-absorbing system 50 may comprise a single device 51’ arranged between the sub-frame 11 and the cross-member 7, as shown in figure 11. The device 51’ is then preferably equidistantially spaced from both rails 6. A single device 51’ may require a larger cross-section than two devices 51 arranged in parallel to get a similar performance. Having a single device 51 ’ requires less assembly time for attaching the energyabsorbing system 50 on the frame 3. It may also be advantageous in terms of packaging as it generally occupied less space.

[0058] Whatever the number of devices 51, 51’ in the energy-absorbing system 50, the device may have a circular or rectangular cross-section. The device 51, 51’ may have a straight shape or, alternatively (as shown in figure 13), it may have a tapered shape, preferably towards the rear of the vehicle 1. The wall thickness of the device 51, 51’ may be comprised between 1,5 and 4 mm.

[0059] As illustrated in figure 12, the energy-absorbing system 50 may have a honeycomb inner structure, i.e. may include an array of hollow cells formed between fairly thin walls. The cells may be columnar and hexagonal in shape. Such an arrangement has a high ability to absorb energy through compressive loading.

[0060] As illustrated in figure 13, the energy-absorbing system 50 may comprise a hollow body 52 having an axis 53 which is substantially parallel to the longitudinal direction X, in the mounted position. The section of this hollow body 52 can have various shapes. For example, the hollow body 52 may be a circular tube. Alternatively, the hollow body 52 can include plates welded together along their longitudinal edges. In the example of figure 13, the hollow body 52 is made of two identical folded plates 54, each plate having a substantially C- shaped cross-section and opposed longitudinal edges or rims 55, the facing edges or rims of the plates 54 being welded to one another. Besides, the hollow body 52 may have a section area which decreases forwardly, i.e. a forwardly converging shape.

[0061] Optionally, the energy-absorbing system 50 comprises a crash initiator 56. Such a crash initiator is a structure or a device that facilitates the control of axial deformation of the energy-absorbing system 50. Said crash initiator 56 can have various shapes are be made in various ways. For example, it can comprise beads, notches, holes, a zone with a reduced thickness, etc. The crash initiator 56 can be stamped on the energy-absorbing system 50. It may be configured to cause a gradual buckling of the energy-absorbing system 50. In the exemplary example of figure 13, the crash initiator 56 comprises substantially annular grooves stamped on the hollow body 12, and spaced apart from each other along the axis 53. The grooves may have a length of around 150 mm and a depth comprised between 4 and 7 mm. Grooves may be arranged envery 35 - 40 mm along the longitudinal direction X.

[0062] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. 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. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. 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.

[0063] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0064] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. [0065] 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 this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0066] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the inventive concepts being set forth in the following claims.