Abstract:
Knee support element for motor vehicles for absorbing energy in a knee region in case of a crash of the vehicle, including a first deformation element for absorbing energy upon impact of the knees in a first impact zone and a second deformation element for absorbing energy upon impact of the knees in a second impact zone, where the first deformation element is linked to the second deformation element in order to deform the second deformation element and thereby limit the resistance of the second deformation element against deformation, upon impact on the first impact zone.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a knee support element for motor vehicles or absorbing energy in the knee region in case of a crash of the vehicle. 
   Knee support element according to the present invention is positioned between a support element of a motor vehicle and an element such as the instrument panel facing the cabin of the motor vehicle. 
   The knee support element is typically positioned in between the cross car beam (CCB) and the instrument panel (IP) of a vehicle. 
   During a frontal crash of a car, in case the driver and/or the passenger sitting next to the driver, are not wearing a safety belt, the knees region absorbs an important amount of energy. During the crash the knees will move towards the instrument panel and have an impact on the instrument panel. Underneath the instrument panel energy absorbing brackets will be present to absorb the energy of the incoming knees. 
   Regulations according to the energy absorption of the instrument panel and the underlying brackets can be found for unbelted dummies in the American standards USFMVSS208. 
   There are a wide range of possible knee contact points with the instrument panel as well as different knee impacts directions which needs to be covered by using appropriate support brackets. In the prior art it is customary to work with dummies with different sizes. The energy absorbing brackets should be capable of absorbing a sufficient amount of energy in case of a frontal crash with any unbelted dummy. 
   In the present text, references will be made to different dummies being the 5%, 50% and 95% dummy. The 5% dummy represents relatively small driver. The knees of the unbelted dummy will have impact on a relatively low point of the instrument panel. The 50% dummy represents an average driver. The 50% dummy represents an impact of the mid section of the instrument panel. A 95% dummy represents a relatively tall driver. The 95% dummy will have an impact on a relatively high part of the instrument panel. The brackets should be adapted to ensure that the forces and the moments which occur in the femur and the tibia of a driver during impact are not allowed to exceed a certain value. These values are limited by European, US, Japanese and comparable safety regulations and norms. 
   In the prior art a knee support for a motor vehicle is known with a cross section which resembles a L. These brackets are known from the American patent application US2003/0057692 (Horsch et al.). 
   The knee support according to the prior art is positioned in order to have the relatively long part of the L connected to the CCB wherein this long part faces in is directed towards the passenger cabin. The smaller leg of the L points downwards. The bracket according to the prior art is positioned in order to have the connection between the two legs of L in the 50% dummy region. That means that upon impact of a 50% dummy an optimal absorption of energy is possible. As shown in  FIG. 5  of US2003/0057692 in the mid section the brackets are only connected to the CCB with the relatively long part of the L. This means that the bracket is not suitable of absorbing a relatively large amount of energy upon impact of a 5% dummy. The bigger the size of the car, thereby the longer the leg of the L facing downward, the more difficult it will be to ensure upon impact a high energy absorption of the 5% dummy. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a knee support according to the introduction, wherein the knee support element is capable of providing suitable energy absorption for the 50%, 5% and the 95% dummy. 
   The object is achieved in that the knee support element comprises a first deformation element for absorbing energy upon impact of the knees in a first impact zone, and a second deformation element for absorbing energy upon impact of the knees in a second impact zone, wherein the first deformation element is linked to the second deformation element in order to deform the second deformation element and thereby limit the resistance of the second deformation element against deformation, upon impact on the first impact zone. It is possible that the first deformation element is linked to the second deformation element in order to deform and thereby displace the second impact zone upon impact on the first impact zone. 
   It is possible that the first and the second deformation elements are linked in order to move the second deformation element in direction away from the tibia upon impact of the knees on the first impact zone. 
   The knee support element according to the present invention has the effect that the first deformation element can be positioned in a motor vehicle in order to provide optimal energy absorption for a 50% dummy. The second deformation element can be positioned in a motor vehicle in order to provide optimal energy absorption for a 5% dummy. The impact zone of the first and the second deformation element can be connected by means of a force distribution plate which is elongated in order to also provide sufficient absorption for a 95% dummy. 
   The first and the second deformation element are linked in order to have a displacement of the second impact upon impact on the first impact zone. This feature is added because of the fact that upon impact of the knees in the first impact zone the presence of the second deformation element is positioned in the impact zone of the tibia of the 50% dummy. The presence of the second element might lead to excess of the forces and moment exerted on the tibia above the regulations and norms. Upon impact on the first impact zone the linkage between the first deformation element and the second deformation element will cause a deformation of the second deformation element, which deformation will move the second impact zone away from the tibia. That means that the linkage will avoid fracture of the tibia upon impact of the knee in the first impact zone. 
   According to the present invention it is possible that the first deformation element and the second deformation element are a first part and a second part of a single support bracket. 
   In order to fine tune the resistance of the first and/or the second deformation element it is possible that at least one of the first and second deformation element is provided with notches, in order to tune the resistance of the first and/or second deformation element by altering the dimensions of the notches. 
   According to the present invention it is possible that the first and the second deformation element comprise one single material. Alternatively it is possible that the first and the second deformation element comprise a first and a second material. 
   Each or one of the deformation elements might comprise one of the following materials: steel, aluminium, magnesium, plastic, composites, foam, rubber or any suitable material or combinations of those materials. 
   It is possible that the first and/or second deformation element comprise a spring. 
   According to the present invention it is possible that the first deformation element is provided with connecting means for connecting the first deformation element to a support element of a motor vehicle. Thereby it is possible that the second deformation element is provided with connecting means for connecting the second deformation element to a support element of a motor vehicle. Alternatively it is possible that the first and second deformation element are provided with a single connecting element for connecting the first and the second deformation element to a support element of a motor vehicle. 
   It is possible that the first and/or second deformation element is connected to the cross-car-beam (CCB). 
   It is possible that the first and/or second deformation element is connected to the car body. 
   It is possible that the first and/or second deformation element connected to a deformable bracket which is attached to the cross-car-beam, or the car body. 
   It is possible that the support bracket is produced by means of moulding. 
   According to the invention it is possible that the first impact zone and the second impact zone are linked by means of a force distribution plate. The impact zones can also be integrated in the force distribution plate. Thereby it is possible that force distribution plate is formed by an instrument panel (IP) of the vehicle. 
   The present invention also relates to a motor vehicle, such as a car, comprising a knee support element wherein the knee support element is positioned in order to place the first impact zone in the 50% impact area and wherein the second impact zone is placed in the 5% impact area. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to the drawings, wherein: 
       FIG. 1  shows a first embodiment of the knee support element according to the present invention; 
       FIG. 2  shows a second embodiment of the knee support element according to the invention; 
       FIG. 3  shows a third embodiment of the knee support element according to the present invention; 
       FIG. 4  shows a fourth embodiment of the knee support element according to the present invention; 
       FIG. 5  shows the knee support element according to  FIG. 4  where by pressure is exerted on the first impact zone in order to deform the first deformation element; 
       FIG. 6  shows a further embodiment of the knee support element according to the present invention; 
       FIG. 7  shows a further embodiment of the knee support element according to the present invention; 
       FIG. 8  shows a further embodiment of the present invention; 
       FIG. 9  shows a further embodiment of the present invention; 
       FIG. 10  shows a further embodiment of the knee support brackets according to the present invention; and 
       FIG. 11  shows an embodiment of the knee support structure according to the present invention consisting of a single bracket. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a first embodiment of the knee support element  1  according to the present invention. The knee support element comprises a first deformation element  11 , a second deformation element  21  and a linking member  3 . A first end of the first deformation element  11  is connected to a support element  4  of a motor vehicle, such as a car. This support element  4  is for instance the cross car beam (CCB). The second end of the first deformation element  11  provides a first impact zone A. In  FIG. 1  with F 1  an impact force exerted by knee  5  on the first impact zone A is schematically indicated. 
   Second deformation element  21  is with one end thereof connected to a support element  6  of a motor vehicle. This support element  6  can also be the cross car beam or it can be another support element of a motor vehicle. The other end of the second deformation element provides a second impact zone C. With F 2  the force exerted by the knee  5  or the tibia  5   a  on the second impact zone C is schematically indicated. The first impact zone A of the first deformation element  11  is positioned to be in the area to essentially support an impact of a 50% or a 95% dummy. The impact zone can also be positioned in order to be in-between the impact zone of a 50% dummy and a 95% dummy. 
   The second impact zone C is essentially positioned in order to support impact of the knees of a 5% dummy. 
   As indicated below in  FIG. 2 , the first and the second impact zone C can be connected by means of a force distribution plate. That means that an impact in-between the first and second impact zone can be evenly distributed to the respective impact zones A, C. 
   With reference to  FIG. 1 , in case the knees  5  of a 50% dummy impact on the first impact zone A, the first deformation element will be deformed. Because of this deformation, the first deformation element is able to absorb the energy exerted by the knees  5  upon the first deformation element  11 . Because of the linking member  3  the deformation of the first deformation element  11  will cause a deformation of the second deformation element  21 . As indicated in  FIG. 1 , the second deformation element  21  consist of a first part  21   a  in-between the second impact zone C and point D and a second element  21   b  in-between point D and the connection of the second deformation element with the car support element  6 . 
   Upon impact on the impact zone A, the deformation of the first deformation element  11  will be transported via the liking member  3  to displace point D and thereby move the second impact zone C in a direction away from the impact area of the tibia. 
   The effect of this measure is that in case the tibia  5   a  of a passenger will impact on the second impact zone C, the resistance against this impact will be relatively low and will not exceed the forces and limitations which might lead to a fracture of the tibia. 
   In case the knees, for instance of a 5% dummy, would directly have impact on the second impact zone C, the presence of the second deformation element  21  will provide sufficient resistance in order to decelerate the knees without exceeding the limitations and forces which might lead to fracture of the knees. Also in this case the linkage between the first deformation element  11  and the second deformation element  21  will help to protect the passenger. The deformation of the second deformation element  21  will, because of the linking member  3 , also cause a deformation of the first deformation element  11 . 
   Depending on the dimensions of the car and the materials used, the first deformation element  11 , the second deformation element  21  and the linking member  3  and the relative position thereof can be tuned in order to provide optimal protection for impact of a passenger of any size without risking to exceed forces and limitations which might lead to fractures of the legs of the passenger. 
     FIG. 2  shows an alternative embodiment of the knee support element according to  FIG. 1 . The knee support element  101  according to  FIG. 2  comprises a first deformation element  111  comprising a first  111   a  and a second  111   b  cylindrical element. A first end of the first deformation element  111  is connected to a rigid part of the car, such as the cross car beam  4 . This connection is indicated with point B. The other end of the first deformation element  111  provides a first impact zone A. The knee support element  101  according to  FIG. 2  further comprises a second deformation element  121 , with one end thereof connected to the cross car beam  4  and wherein the other end provides a second impact zone C. 
   Similar to embodiments according to  FIG. 1 , the first deformation element  111  and the second deformation  121  are connected by means of a linking member  103 . 
   The impact zones A and C are interconnected by means of an additional connecting element  7  indicated by means of dotted line, or by a force distribution plate. Moreover the force distribution plate  8  is shown which is connected to the knee support element  101 . 
     FIG. 3  shows a third embodiment  201  of the knee support element according the present invention. The knee support element  201  according to  FIG. 3  comprises a first deformation element  211 , comprising a first  211   a  and a second  211   b  and a third  211   c  cylindrical element. Similar to  FIG. 2  the first deformation element  211  is with one end thereof connected to a car cross beam  4  while the other end provides an impact zone A. 
   Moreover the element  201  comprises a second deformation element  221 . The second deformation element  221  with one end thereof is connected to a rigid part  6  of a vehicle. The other end provides a impact zone C. Similar to  FIG. 2 , the impact zone A and C can be connected by an additional connecting element  7 . Moreover the force distribution plate and the instrument panel  8  are shown. 
   As indicated in  FIG. 3 , the first impact zone, is essentially in the 50%-95% dummy area. The second impact zone C is provided in the 5% impact zone. 
   The knee support element according to  FIGS. 2 and 3  can be produced from any suitable material such as aluminium, steel, magnesium, plastic or any combination thereof. The elements can for instance be produced by means of extrusion, die-casting, stamping, deep drawing, moulding, roll forming. 
     FIG. 4  shows a further alternative for a knee support element  301 , according to the present invention. The firs deformation element  311  is basically shaped as cylinder having corrugate walls. The second deformation element  321  has a shape of a wall. Linking member  3  connects the second deformation element with the first deformation element. 
   In  FIG. 5  the effect of an impact, F 1 , exerted on the first impact zone A is shown. Because of the impact F, the first deformation element  311  is deformed. This deformation will have the effect that point F is moved towards the cross car beam  4 . Because of the interconnection of the walls  321   a  and  321   b  and  3 , the interconnecting point D will move in the direction away from the impact F 1 . Because of this movement the second impact zone C will move in a direction away from the impact F 1 . That means that in case F 1  is generated by the knees of passenger, the lower tibia will be protected by means of the movement of the impact zone in order to limit the forces exerted on the tibia upon impact. 
     FIG. 6  shows an alternative embodiment of a knee support element  401 . The knee support element  401  comprises a first deformation element  411  and a second deformation element  421 . Both the first  411  and the second  421  deformation elements are connected at one end thereof to the force distribution plate and instrument panel  8 . The other end thereof is connected to a support member  9 . The support member  9  with one end thereof is connected to the rigid part of the motor vehicle, such as the cross car beam  4 . 
   Similar to the  FIG. 1-5 , upon impact of the knees in the first impact zone A, the first deformation element  411  will be deformed thereby displacing point B on member  9 . The displacement of point B will result on a displacement of point E away from the impact direction of the force on the impact zone A. Because of the displacement of point E the connected second deformation element  421 , would be moved away in a direction away from the impact on the first impact zone A. 
     FIG. 7  shows a further embodiment of knee support element  501 , similar to the element  401  according to  FIG. 6 . 
   The support element  501  comprises a first deformation element  511  which is provided between the instrument panel  8  and a support member  509 . The support element  509  is connected to the cross car beam  4 . A second impact zone C is created on a further end of the support member  509  in case impact is received on the first impact zone A, the support element  509  will rotate and thereby displace the second impact zone C in a direction away from the impact received on impact zone A. 
   In  FIG. 7 , by means of reference number  10  a notch is indicated. This notch can be used in order to fine tune the resistance against deformation of the member  509 . It is clear that such a notch can also be used in one of the other elements in one of the embodiments shown on the knee support according to the present invention. 
     FIG. 8  provides a further embodiment of a knee support element  601  according to the present invention. Similar to  FIG. 7  a support member  509  is connected to a car cross being for to the support member  509  a single element  612  is provided. This element  612  provides a deformation zone in between the first impact zone A and the connection B of the element  612  and the support member  509 . In  FIG. 8  also the instrument panel and the force distribution plate are schematically indicated. 
     FIG. 9  provides a further embodiment of a knee support element  701  according to the present invention. 
   The knee support element  701  comprises a support member  709 . A first deformation element  711  is provided in between the first impact zone A and a connected point B which connect the first deformation element  711  with the support member  709 . In the support element  709  two notches  10  are provided in order to fine tune the resistance of this member  709  against deformation. The impact zones A and C are interconnected by a means a fourth distribution plate  7  (indicated by dotted lines) and the instrument panel  8 . Moreover possible positions for the 5%, 50% and 95% dummies impact zones are also indicated. 
   An alternative embodiment is indicated in  FIG. 10 . The knee support element  801  comprises a first element  802  which provides in between the impact zone A and point B a first deformation element. The continuation of element  802  is connected to the second impact zone C. The support element  809  connects element  802  with a rigid part  4  of the motor vehicle. The resistance of the element according to  FIG. 10  can be fine tuned, for instance, by alternating the curvature of the element  802 . 
     FIG. 11  shows a further embodiment of a knee support element  901  according to the present invention. The knee support element  901  is a single element which provides in between the impact zone A and point B a first deformation element  911 . Upon impact of a force in the first impact zone A, the knee support element will rotate with respect to the rigid car part  4 . The element between the impact zone A and C provides a local force distribution. In  FIG. 11  also the instrument panel and the force distribution plate are schematically indicated. 
   With reference to the figures indicated above, it is noted that the resistance of the first and second deformation element and thereby the ability to absorb forces can be easily tuned by modifying the shape, the material, the thickness and the links of the whole as indicated in the figures. Not only the amount of forces received on the brackets, but also the angle or directions thereof can be fine tuned by amending the form, depending on the specific dimension of a motor vehicle.