Patent Publication Number: US-2023136543-A1

Title: Vehicle comprising a collision protection structure

Description:
TECHNICAL FIELD 
     The invention relates to a vehicle. In particular, it relates to a vehicle comprising a collision protection structure. 
     The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will mainly be described with respect to a truck, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as passenger cars. 
     BACKGROUND 
     In the vehicle industry, much effort is put in the development of electrically driven heavy-duty vehicles. It is desirable to used substantially the same platform for assembling an electrically driven vehicle as for a corresponding vehicle propelled by an internal combustion engine. For instance, an electric truck built on the same platform as a truck of the type having an internal combustion engine underneath the cab, will normally have the frame rails provided with battery packs, while the space underneath the cab may be utilized for other components where the internal combustion engine would have been located. However, for such electric trucks, the battery packs will add mass behind the cab on the frame sides and higher stiffness. These two points combined means that, in case of a frontal collision, the energy has to be absorbed in the frontal area of the truck. The frame sides do not give enough absorption to reduce the cab intrusion to an acceptable level. This may result in a safety problem for the driver. 
     Furthermore, since an internal combustion engine will normally act as a mass damper, when removing the engine there is nothing there to counter-balance the unbalances from the tires and road. This may result in less comfort for the driver. 
     SUMMARY 
     An object of the invention is to provide a vehicle which mitigates the drawbacks mentioned above. 
     The object is achieved by a vehicle according to claim  1 . Thus, the present disclosure provides a vehicle, comprising
         a rear end,   a front end located forwardly of the rear end, wherein a direction extending from the rear end towards the front end or vice versa is defined as a longitudinal direction of the vehicle,   a chassis extending between the rear end and the front end, the chassis comprising two frame members having their main directions of extension along the longitudinal direction and being located on a respective side of a longitudinal geometrical centre axis of the chassis,   resilient elements, such as bushings, provided on the chassis, and   a collision protection structure located between said two frame members and configured to absorb energy by becoming deformed when the chassis is subjected to a rearwardly directed impact force which is greater than a threshold force, wherein the collision protection structure is suspended from the chassis by said resilient elements so as to act as a mass damper under normal operating conditions.       

     The inventive concept is based on the insight that an additional structure may be provided not only to absorb energy for reducing cab intrusion, but also for functioning as a mass damper if suspended from resilient elements (such as the resilient elements form which an internal combustion engine would have been suspended). Thus, a synergetic effect is achieved by the vehicle of this disclosure, in particular because of the suspension of the collision protection structure, as stated above. 
     According to at least one exemplary embodiment, the vehicle is an electric vehicle, such as an electric truck, propelled by electric energy stored in a battery. However, it should be understood that the general inventive concept may be implemented for other types of vehicles as well, such as hydrogen gas powered vehicles, etc. 
     According to at least one exemplary embodiment, the vehicle comprises a cab, wherein the collision protection structure is located underneath the cab. This is advantageous, since it provides a mass damping function, improving the driver comfort for a driver sitting in the cab when the vehicle is driven under normal operating conditions, i.e. not in a collision. 
     According to at least one exemplary embodiment, the chassis comprises a rear cross member located rearwardly of the collision protection structure and interconnecting the two frame members of the chassis, wherein when the chassis is subjected to said rearwardly directed impact force which is greater than a threshold force, then said rear cross member acts as an abutment and counteracts or retards a rearward movement of the collision protection structure. This is advantageous since the abutting function of the rear member will result in absorption of at least some, or most, of the kinetic energy of the collision protection structure by deformation thereof. 
     According to at least one exemplary embodiment, the chassis comprises a front cross member located forwardly of the collision protection structure and interconnecting the two frame members of the chassis, wherein when the chassis is subjected to said rearwardly directed impact force which is greater than a threshold force, then said front cross member is configured to press the collision protection structure rearwards. This may suitably be due to the two frame members of the chassis buckling upon a collision, wherein the buckling causes the front cross member to move rearwardly and thereby pressing the collision protection structure rearwardly. Thus, some of the kinetic energy resulting from the collision will be transferred to the collision protection structure. 
     According to at least one exemplary embodiment, the collision protection structure is configured to be deformed between the front cross member and the rear cross member when the chassis is subjected to said rearwardly directed impact force which is greater than a threshold force. Thus, the front cross member may transfer some of the kinetic energy resulting from a collision to the collision protection structure, which will then be absorbed when the collision protection structure is pressed against the rear cross member, which thus together with the front cross member deformed the collision protection structure. 
     According to at least one exemplary embodiment, when said two frame members of the chassis deform in reaction to a collision of the vehicle, the collision protection structure is configured to limit and/or counteract further deformation of said two frame members. In particular, if the collision protection structure is placed between the front cross member and the rear cross member, then the added structural strength provided by the collision protection structure may counteract the buckling of the two frames of the chassis. At relatively low loads, the collision protection structure may remain substantially undeformed. In particular, at relatively low loads the collision protection structure may be stiff enough and have sufficient structural strength to hold against the front cross member and rear cross member, preventing the front cross member to move further rearwards, and thus counteracting progression of the chassis frames buckling. This also reduces the risk of cab intrusion. 
     According to at least one exemplary embodiment, the collision protection structure comprises a subframe suspended between the two frame members of the chassis. The subframe may suitably have the form of an open cage. For instance, the subframe may have a lower cage side and lateral cage sides. Suitably, the cage is open from above, enabling components/sub-modules to be lowered into the cage shape. Thus, the subframe may provide a simple and time-efficient mounting of components/sub-modules to the subframe. Furthermore, as will be discussed in more detail below, in at least some exemplary embodiments there are connection elements connected to the subframe for mounting the collision protection structure to said resilient elements. Thus, once the components/sub-modules have been received by the subframe, the entire collision protection structure with its cargo can be mounted to the chassis by connecting the connecting elements to said resilient elements. 
     According to at least one exemplary embodiment, the subframe comprises two longitudinal subframe portions extending generally in the longitudinal direction of the vehicle and being located on a respective side of a central vertical plane containing said longitudinal geometrical centre axis, wherein when the chassis is subjected to said rearwardly directed impact force which is greater than a threshold force, then each one of said longitudinal subframe portions is configured to split up the energy reaching the longitudinal subframe portion as a result of said impact force, along at least two longitudinal load paths formed by two sections of the longitudinal subframe portion. This is advantageous since the rearwardly directed energy is not focussed to one path, but instead each load path will have a reduced rearwardly directed energy. Each longitudinal subframe portion may suitably form a lateral cage side, or form part of a lateral cage side, at least in embodiments in which the subframe has a cage-like configuration. The two sections forming the two load paths of each longitudinal subframe portion, may suitably be vertically separated to form such lateral cage sides. 
     This is reflected in at least one exemplary embodiment, according to which, for each longitudinal subframe portion, the two sections that form the longitudinal load paths are vertically separated, forming an upper section and a lower section. Thus, this contributes to the robustness and load distribution capability of the collision protection structure. 
     According to at least one exemplary embodiment, the subframe comprises one or more cross beams interconnecting said longitudinal subframe portions with each other, thereby providing a shortened unsupported length of the longitudinal subframe portions, wherein said one or more cross beams support, for each longitudinal subframe portion, at least one of said sections forming the longitudinal load paths. For instance, in some exemplary embodiments, the one or more cross beams may extend between the lower sections forming the longitudinal load paths. In some exemplary embodiments, the one or more cross beams may extend between the upper sections forming the longitudinal load paths. In some exemplary embodiments, the one or more cross beams may extend between both the lower and the upper sections forming the longitudinal load paths. 
     In at least some exemplary embodiments in which the subframe has a cage-like configuration, one or more of said cross beams may suitably form a bottom cage side. In some exemplary embodiments, such cross beams forming a bottom cage side may be configured to receive sub-modules, such as sub-modules of a traction battery propulsion system. In some exemplary embodiments, sub-modules may comprise one or more of battery components (such as high voltage or traction voltage components), cooling pumps, steering pump, climate module, and air compressor. 
     Thus, in a general sense, according to at least one exemplary embodiment, the collision protection structure is configured to form a platform or support for carrying at least one vehicle sub-module, such as battery components (such as high voltage or traction voltage components), cooling pumps, steering pump, climate module and air compressor. 
     According to at least one exemplary embodiment, for each longitudinal subframe portion, the sections forming the longitudinal load paths are less stiff (softer) relative to at least one of a forwardly and a rearwardly adjacent section of the subframe portion. By having sections with different properties, the energy is managed in an efficient way and the behaviour of the collision protection structure may be controlled and predicted. It should be noted that in other exemplary embodiments, for each longitudinal subframe portion, the sections forming the longitudinal load paths may instead be stiffer than at least one of said forwardly and said rearwardly adjacent section of the subframe portion. Other sequences of soft and stiff sections are also conceivable. 
     According to at least one exemplary embodiment, the collision protection structure is a frontal collision protection structure. Thus, the collision protection structure is particularly advantageous for handling frontal collisions. 
     According to at least one exemplary embodiment, the number of said resilient elements is at least three, wherein the collision protection structure comprises at least one rear connection element at a rear end area of the collision protection structure for connecting to at least one of said resilient elements, and at least one front connection element at a front end area of the collision protection structure for connecting to at least another one of said resilient elements. Advantageously, the same resilient elements and the same locations of the resilient elements may be used as would otherwise have been used for mounting an internal combustion engine. For instance, rubber bushings which would normally be used for mounting an internal combustion engine may now instead be used for suspending the collision protection structure. 
     It should also be understood that front and rear bushings, to which the front and rear connection elements are configured to be connected, may be existing standard bushings on a vehicle or may be separate bushings applied to the vehicle. 
     According to at least one exemplary embodiment, each one of said two frame members of the chassis carries at least one of said resilient elements. Suitably, each of the two frame members carries at least one rear resilient element for receiving rear connection elements of the collision protection structure. There rear resilient elements may suitably be or correspond to existing standard resilient elements (such as rubber bushings). The rear resilient elements may suitable be provided on a centrally facing surface of the respective frame members. 
     According to at least one exemplary embodiment, the front cross member carries at least one of said resilient elements, which is in the form of a front resilient element, for receiving the front connection element of the collision protection structure. Suitably the front cross member carries two or more resilient elements, such as rubber bushings, for receiving mating front connection elements of the collision protection structure. 
     Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. 
       In the drawings: 
         FIG.  1    illustrates a vehicle, in accordance with at least one exemplary embodiment of the invention. 
         FIG.  2    is a perspective view of a collision protection structure, in accordance with at least one exemplary embodiment, which may be provided in the vehicle illustrated in  FIG.  1   . 
         FIG.  3    is a side view of a part of the collision protection structure. 
         FIG.  4    is a top view of the collision protection structure. 
         FIGS.  5 - 7    illustrate a deformation sequence of the collision protection structure upon a frontal collision of the vehicle. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION 
       FIG.  1    illustrates a vehicle  1 , in accordance with at least one exemplary embodiment of the invention. Although the vehicle  1  is illustrated in the form of a truck, other types of vehicles, such as busses, construction equipment, trailers or passenger cars may be provided in accordance with the invention. 
     The truck (vehicle) comprises a cab  2  in which a driver may operate the vehicle  1 . The vehicle  1  comprises a number of road wheels  4 , herein illustrated as two pairs of wheels, however in other embodiments there may be a different number of wheels, such as three pairs, four pairs or more. 
     The vehicle  1  comprises a rear end  6 , a front end  8  located forwardly of the rear end  6 , wherein a direction extending from the rear end  6  towards the front end  8  or vice versa is defined as a longitudinal direction of the vehicle. A chassis  10  extends between the rear end  6  and the front end  8 , and a collision protection structure (not shown) is suspended from the chassis  10 , as will be described in more detail in connection with  FIG.  2   . 
       FIG.  2    is a perspective view of a collision protection structure  20 , in accordance with at least one exemplary embodiment, which may be provided in the vehicle  1  illustrated in  FIG.  1   . Suitably, the collision protection structure  20  is located underneath the cab  2 , at a location corresponding to where an internal combustion engine would have been located under the cab  2 . 
     As shown in  FIG.  2   , the chassis  10  comprises two frame members  60  having their main directions of extension along the longitudinal direction of the vehicle and being located on a respective side of a longitudinal geometrical centre axis x of the chassis (the geometrical centre axis is indicated in  FIG.  4   ). The frame members  60  may also be referred to as frame rails. 
     Continuing with  FIG.  2   , the chassis  10  comprises a rear cross member  62  interconnecting the two frame members  60 . The chassis  10  also comprises a front cross member  64  interconnecting the two frame members  60 . Thus, the front cross member  64  is located forwardly of the rear cross member  62  as seen in the normal driving direction of the vehicle (i.e. when not driving in reverse). The front cross member  64  is provided with resilient elements  66 , herein illustrated as a pair of bushings, of the type normally used for suspending an internal combustion engine. Similarly, near the rear cross member  62 , there are resilient elements  68  provided at the two frame members  60 , here illustrated as provided on a centrally facing side of the respective frame member  60 . Theses rear resilient elements  68  are located slightly forwardly of the rear cross member  62 . 
     It should be noted that the number and type of resilient elements  66 ,  68 , as well as their placements may be different in other exemplary embodiments. For instance, the resilient elements  66  at the front cross member  64  may in other exemplary embodiments instead be provided on the two frame members  60 , similarly to the rearwardly located resilient elements  68 . In other exemplary embodiments, the front cross member  64  may instead of carrying two resilient element  66 , only have one centrally located resilient element. Many other alternations are of course conceivable. Suitably, the total number of said resilient elements  66 ,  68  (i.e. including both the front and the rear resilient elements) is at least three. 
     Regardless of the type, number and location of the resilient elements, according to the present inventive concept, the collision protection structure  20  should be suspended from the chassis  10  by said resilient elements  66 ,  68  so as to act as a mass damper under normal operating conditions. Thus, it is configured to counteract or reduce the amplitude of mechanical vibrations, thereby promoting driver comfort. Accordingly, the collision protection structure  20  is enabled to move relative to the resilient elements  66 ,  68  to which it is connected. 
     Furthermore, the collision protection structure  20  should be located between the two frame members  60  and be configured to absorb energy by becoming deformed when the chassis  10  is subjected to a rearwardly directed impact force which is greater than a threshold force. 
     The selected threshold force should, of course, be dependent on various factors, such as dimensions, strengths, structural features of the vehicle, etc. The collision protection structure  20  and its strength and deformation characteristics should therefore be dimensioned accordingly, based on the properties of the vehicle for which it is intended to be used. 
     The collision protection structure  20  may suitably comprise at least one rear connection element  22  at a rear end area of the collision protection structure for connecting to at least one of said resilient elements  68 . In the illustrated exemplary embodiment, there may be two rear connection elements  22 , one for each rear resilient element  68  located on a respective one of the two frame members  60 . Similarly, the collision protection structure  20  may suitably comprise at least one front connection element  24  at a front end area of the collision protection structure  20  for connecting to at least another one of said resilient elements  66 . In the illustrated exemplary embodiments, the collision protection structure  20  has two front connection elements  24 , one for each front resilient element  66  provided on the front cross member  64 . 
     As illustrated in  FIG.  2   , the collision protection structure  20  may be located between the front cross member  64  and the rear cross member  62 . The rear cross member  62  is located rearwardly of the collision protection structure  20 , and will (as explained later) when the chassis  10  is subjected to a rearwardly directed impact force which is greater than said threshold force, act as an abutment and will counteract or retard a rearward movement of the collision protection structure  20 . The front cross member  64  is located forwardly of the collision protection structure  20 , and will (as explained later) when the chassis  10  is subjected to said impact force, press the collision protection structure  20  rearwardly. Thus, the collision protection structure  20  may become squeezed between front cross member  64  and the rear cross member  62 , wherein as the collision protection structure  20  deforms between the front cross member  64  and rear cross member  62  it will absorb at least some of the energy from the impact. 
     Thus, according to at least one exemplary embodiment the collision protection structure  20  is configured to be deformed between the front cross member  64  and the rear cross member  62 , when the chassis  10  is subjected to said rearwardly directed impact force which is greater than a threshold force. 
     According to at least one exemplary embodiment when the two frame members  60  of the chassis  10  deform in reaction to a collision of the vehicle, the collision protection structure  20  is configured to limit and/or counteract further deformation of the two frame members  60 . Thus, the collision protection structure  20  may function as a strengthening structure to which the frame members  60  are connected, wherein the collision protection structure  20  may brace against the front cross member  64  and rear cross member  62  counteracting further rearward movement of the front cross member  64 , thereby limiting and/or counteracting further deformation of the connected two frame members  60 . 
     The collision protection structure  20  may comprise a subframe suspended between the two frame members  60 . The subframe is here illustrated as having the form of an open cage, having a lower cage side and two lateral cage sides. The cage is open from above, enabling components/sub-modules to be lowered into the cage shape. The lateral cage sides may be formed by two longitudinal subframe portions  26  extending generally in the longitudinal direction of the vehicle and located on a respective side of a central vertical plane containing the longitudinal geometrical centre axis x of the vehicle. When the chassis  10  is subjected to the impact force greater than the threshold force, then each one the longitudinal subframe portions  26  is configured to split up the energy reaching the longitudinal subframe portion  26  along at least two longitudinal load paths formed by two sections  26   a ,  26   b  of the longitudinal subframe portion  26 . The two sections  26   a ,  26   b  of one of the longitudinal subframe portion  26  can be seen more clearly in the side view in  FIG.  3   . 
       FIG.  3    is a side view of a part of the collision protection structure. As can be seen, the lateral cage side is formed by a generally longitudinal subframe portion  26 , which in turn comprise two sections  26   a ,  26   b  for splitting the energy along two longitudinal load paths. The two sections  26   a ,  26   b  that form the longitudinal load paths are vertically separated, thus forming an upper section  26   a  and a lower section  26   b . An incoming force F is thus illustrated as being split into a force F 1  along the upper section  26   a  and a force F 2  along the lower section  26   b . Reinforcement sections  28  may extend between the upper section  26   a  and the lower section  26   b.    
     Turning back to  FIG.  2   , as can be seen, the subframe may comprise one or more cross beams  30  interconnecting the longitudinal subframe portions  26  with each other. At least some of the cross beams  30  may form a bottom or lower side of the previously discussed cage-like structure. The cross beams  30  provide a shortened unsupported length of the longitudinal subframe portions  26 . Thus, one or more of said cross beams  30  support, for each longitudinal subframe portion  26 , at least one of the two sections  26   a ,  26   b  forming the longitudinal load paths. In accordance with the illustrated exemplary embodiment, the majority or all of the cross beams  30  may support the lower section  26   b . However, in other exemplary embodiments, one or more of the cross beams  30  may, for instance, support the upper section  26   a.    
     In the illustrated exemplary embodiment, the collision protection structure  20  is configured to form a platform or support for carrying at least one vehicle submodule, such as battery components, cooling pumps, steering pump, climate module and air compressor. The platform or support may thus be formed by the lower or bottom side of the cage, i.e. in the illustrated example by at least some of the cross beams  30 . The lower section  26   b  of the load forming paths, may also form part of such a platform or support. The cage shape will also function as a protecting structure for the submodules contained therein, in addition to the benefit of making use of the available space underneath the cab. 
     In the presently illustrated exemplary embodiment, for each longitudinal subframe portion  26 , the sections  26   a ,  26   b  forming the longitudinal load paths are less stiff relative to at least one of a forwardly and a rearwardly adjacent section of the subframe portion  26 . However, in other exemplary embodiments, it may be the other way around, i.e. that the two sections  26   a ,  26   b  are stiffer relative to the forwardly and/or rearwardly adjacent sections of the subframe portions  26 . 
       FIG.  4    is a top view of the collision protection structure  20 . In  FIG.  4    it can be clearly seen that the collision protection structure  20  is suspended between the two frame members  60  of the chassis. In particular, the collision protection structure  20  is suspended from the two front resilient elements  66  provided on the front cross bar  64 , which extends between the two frame members  60 , and from two rear resilient elements  68  provided at a respective one of the two frame members  60 . 
     Suitably, apart from the connection to the resilient elements  66 ,  68 , there is no other contact between the chassis  10  and the collision protection structure  20 , in normal use. In particular, it may be noted that there is a gap between front cross member  64  and the forward-most cross beam  32  of the collision protection structure  20 . The forward-most cross beam  32  of the collision protection structure  20  is thus located rearwardly of and spaced from the front cross member  64  of the chassis  10 . The forward-most cross beam  32  functions as an impact receiving area, as will be explained in more detail later. However, it should be noted that other configurations of the impact receiving area may be conceivable, and may thus not necessarily be represented by a cross beam. The rear end  34  of the collision protections structure  20  will function as an impact conveying area. Again, it should be understood that the configuration, design, shape, etc. for such an impact conveying area may be different in different embodiments. Suitably, the rear end  34  or impact conveying area is located forwardly of and spaced from the rear cross member  62  of the chassis  10 . 
     Turning now to the sequence illustrated in  FIGS.  5 - 7   , these figures illustrate a deformation sequence of the collision protection structure  20  upon a frontal collision of the vehicle. 
     Upon a frontal collision which generates an impact load above a threshold value, the following will occur. 
     Initially, as illustrated in  FIG.  5   , the two frame members  60  of the chassis will start buckling. As a consequence thereof the front cross member  64  will be forced to move rearwardly and will come into contact with the impact receiving area of the collision protection structure  20 , which in this example is represented by the forward-most cross beam  32 . As the buckling of the frame members  60  progresses, the front cross member  64  will push the collision protection structure  20  rearwardly so that the rear end  34  or impact conveying area of the collision protection structure  20  comes into contact with the rear cross member  62 . This is illustrated in  FIG.  6   . At least some of the impact energy will then be absorbed by the collision protection structure  20  as it is pressed between the front cross member  64  and the rear cross member  62 . This is illustrated in  FIG.  7   , which shows collision protection structure  20  in a deformed state. Because the collision protection structure  20  is braced against the front cross member  64  and the rear cross member  62 , the progress of the buckling of the frame members  60  is at least partly counteracted or limited. 
     It is to be understood that the present invention is not limited to the embodiments 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 appended claims.