Abstract:
The invention relates to an impact protection device for rail vehicles, comprising one or more energy absorbing elements ( 25 ) mounted on the main frame of the rail vehicle and having a box-like structure. The invention is characterized in that from the box end in the direction of the main frame ( 29 ) a reverse-drawn recess ( 20 ) and a buffer rod ( 21 ) are provided and the buffer rod can be displaced along the interior wall of the reverse-drawn recess ( 20 ). Elastically deformable energy absorbing elements ( 32 ) such as a friction spring ( 33 ) or a hydraulic capsule ( 34 ) are mounted in the hollow space formed by the buffer rod ( 21 ) and the reverse-drawn recess ( 20 ). The invention provides a greater active length for energy absorption in case of impact than a sequential box arrangement and a standard sleeve buffer.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a crash guard device for a rail vehicle. 
     BACKGROUND INFORMATION 
     FIG. 1 of German Patent Application No. 196 35 221.5 shows a conventional crash guard device for rail vehicles. 
     The device includes energy dissipating elements having a box-shaped structure and a rectangular cross-sectional shape arranged between the main frame of the rail vehicle and the buffer elements. These energy dissipating elements compensate for crash energy that exceeds the energy absorbing power of the buffer elements. German Patent Application No. 196 35 221.5 describes. The embodiment used is characterized in that the cross-sectional shape of the energy dissipating element arranged in each case between the buffer element and the main frame in the form of a closed box-shaped carrier becomes steadily wider in the direction from the buffer element to the main frame. The buffer element is a standard buffer known as a plunger buffer which is known. Such a plunger buffer is composed essentially of a buffer plate  10  mounted on an outside box  11  and inverted over an inside part  12 , as shown in FIG. 1 of the patent application cited above. Outside part  11  and inside part  12  can be displaced into one another, and an energy dissipating element, e.g., in the form of a frictional spring, optionally with an additional hydraulic capsule, is arranged inside part  12 . 
     A disadvantage of the conventional known crash guard device is that due to an tandem connection of the conventional energy dissipating element with a standard buffer, based on total length L of the crash guard device, comparatively little active length is available for absorbing energy. Of the total length of the standard buffer element, only a comparatively small distance is available for pushing outside part  11  over element  12  (distance of travel of the buffer element). In addition, it should be recalled that the full length is not available with the energy dissipating element, but instead a residual length always remains in the compressed state. 
     SUMMARY OF THE INVENTION 
     According to the present invention a significantly greater active length for absorbing energy is made available with the same total length L. 
     It should be pointed out here that according to the latest international guidelines for the safety of rail vehicles (ERRI B 205/RP1), a minimum uptake energy of 1 MJ is specified for deformation zones. In addition, according to these guidelines, a deformation path of 1 meter should not be exceeded. However, UIC 566 specifies a minimum strength of 2000 kN for the structure of the rail vehicle. To absorb the required minimum energy of 1 MJ with a force level below 2000 kN, a deformation length of more than 0.5 meter is necessary. Otherwise, the entire structure of the rail vehicle would have to be designed for a higher strength. There are no conventional crash guard devices at the present having a deformation greater than 0.5 meter. 
     Through an embodiment of a box-shaped energy dissipating element according to the present invention that has an insertion area and a buffer plunger that fits in it and is inserted into it, the energy dissipating element can be designed to be much longer in comparison with conventional devices so that on the whole, a much greater active length is available for dissipating energy. To be able to fully utilize this length, the insertion area must not abut against the main frame when the energy dissipating element crumples, so the main frame is provided with suitable recesses. 
     Advantageous embodiments of the energy dissipation element have a greater stability with respect to lateral forces and torques and eccentric longitudinal forces, torques which deform only through axial buckling in a crash. This makes use of the finding that when deformation is caused in the box by a crash, the deformation stops first in the area of the end of the box, where the box has a smaller cross section. Since the deformation resistance of the box increases progressively due to the increase in cross section in the direction of the main frame, buckling, which progresses axially from the end of the box to the main frame, stops so that uncontrolled collapse such as that which could occur with a box having a constant cross-sectional shape can be ruled out. In another advantageous embodiment, the box is in the shape of a rectangle, at least in the area of the main frame, with the longer sides being positioned horizontally. The lateral supporting forces of the energy dissipating element can be increased in this way. To further increase the lateral supporting forces, lateral reinforcements may be provided according to the present invention, also causing a progressive increase in resistance to axial collapse. Thus, this mostly prevents the deformation from extending to the following structure (main frame). To further ensure a progressively continuous deformation from the end of the box to the main frame through axial collapse, the structure of the box or the energy dissipating element may be provided with weak points in defined areas according to the present invention e.g., in the form of notches in the wall of the box. These weak points can predetermine where and in which order the walls of the box are deformed due to parallel successive folding. The defined weaknesses in the structure of the box are arranged for example, only in the front area of the box or they decrease toward the rear area in the direction of the main frame. The structural measures described here increase safety, so that the box is deformed only due to axial collapse (compression deformation), which is associated with a high energy dissipation, but uncontrolled buckling (bending deformation) of the box, which causes only a slight energy dissipation can be largely ruled out even with eccentric induction of the crash energy. 
     Yet another embodiment according to the present invention has the particular advantage that after deformation of the energy dissipating element, only the outer box need be replaced, while the insertion area and the buffer plunger can be reused, optionally as a separate buffer element. 
     The present invention will now be explained in greater detail below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 shows a conventional crash guard device in an uncompressed state (left) and in a compressed state (right). 
     FIG. 2 shows a first embodiment of a crash guard device according to the present invention that has a box-shaped energy dissipating element with an insertion area. 
     FIG. 3 shows a first embodiment a crash guard device according to the present invention that has a box-shaped energy dissipating element and a separate insertion area. 
     FIG. 4 shows a first embodiment of a flange for mounting an insertion tube on an energy dissipating element according to the present invention. 
     FIG. 5 shows a second embodiment of a flange for mounting an insertion tube on an energy dissipating element according to the present invention. 
     FIG. 6 shows a true-to-scale comparative diagram of active and inactive lengths of a conventional device (bottom diagram) to a device according the present invention (top diagram). 
     FIG. 7 shows a table comparing important dimensions of conventional crash guard devices to a crash device according to the present invention. 
     FIG. 8 shows a side view of a crash guard device that has an advantageous design of a crash element. 
     FIG. 9 shows a cross sectional view in a front area of the crash element along line A—A shown in FIG.  8 . 
     FIG. 10 shows a top view of a crash element having a buffer plunger according to the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention is described in greater detail below on the basis of embodiments and with reference to FIGS. 2 through 10. An insertion area and a buffer plunger which is displaceable on the inside wall of the insertion area are provided in each case from the end of the box in the direction of the main frame. Elastically deformable energy absorbing elements, such as a friction spring and/or a hydraulic capsule are built into the hollow space formed by the buffer plunger and the insertion area. Thus, a greater active length is available for energy dissipation in a crash than would be available with a tandem arrangement of a box and a standard box buffer. 
     FIG. 2 shows a first embodiment of the crash guard device according to the present invention. It is made up of a box-like energy dissipating element  25 , which has an insertion area  20  extending into hollow space  24  and is mounted by welds S on a transverse bar  31  of main frame  29 . Insertion area  20  accommodates a buffer plunger  21  that has a buffer plate  22 . Inside the hollow space formed by the insertion area and the buffer plunger there is an energy absorbing element  32  having a friction spring or spring collar  33  and a hydraulic capsule  34 . The bottom area of insertion area  20  and the end face of the end of the box are designed with reinforcement. Energy dissipating, element  25  is composed of a thick plate and for example has a closed, rectangular cross-sectional shape, with the cross section increasing conically toward the rear to main frame  29  and being mounted on it with the cross-sectional shape of a horizontal rectangle. Guide ribs  40 , for example applied to top side  36  and bottom side  37  as well as side walls  35  by welds S, are provided in hollow space  24 . In the event of a collision of the rail vehicle with energy in excess of the energy absorbing capacity of energy absorbing element  32 , the additional energy is absorbed by deformation of energy dissipating element  25 . Recess  30  ensures that the total length of energy dissipating element  25  can be utilized as a deformable structure, because insertion area  20  can enter this recess  30 . Guide ribs  40  ensure that insertion area  20  passes through recess  30 , in particular with an eccentric collision. 
     FIG. 3 shows a second embodiment of a crash guard device according to the present invention having a separately arranged insertion area  20  (buffer box) to accommodate and guide displaceable buffer plunger  21 , whose end is designed as a plate  22  or is provided with a separate buffer plate. Bottom part  23  of the buffer box may be designed as a plate bottom, for example, depending on requirements, so it is reinforced and optimized in terms of weight. If necessary, the plate bottom may be chamfered on the outside. Insertion area  20  that has buffer plunger  21  is inserted into hollow space  24  of energy dissipating element  25  that has a box-shaped structure and for example a rectangular cross section. To utilize the total length L of the crash guard device as optimally as possible and to make available as much active length as possible, energy dissipating element  25  has a length such that its ends and is attached at the plate end of buffer box  20 . Weld joints and/or detachable connections, e.g., screw connections, may be used to attach buffer box  20  to energy dissipating element  25 . In the embodiment shown in FIG. 3, the plate end of buffer box  20  is designed as a reinforced part  26  which has a greater wall thickness than buffer box  20 . A flange  27  is placed over buffer box  20  and mounted on reinforced end piece  26  by a peripheral weld seam. Head piece  28  of deformable energy dissipating element  25  has a recess through which the entire buffer element can be inserted into hollow space  24  of the energy dissipating element until flange  27  is in contact with the outer surfaces of head piece  28 . The buffer element then can be screwed onto the energy dissipating element. The entire crash guard device is attached by welds S to main frame  29  or its head part of the rail vehicle. Energy dissipating element  25  has a thick plate and a box-shaped structure with a for example closed, rectangular cross-sectional shape. The advantageous embodiment of this energy dissipating element is described in German Patent Application No. 196 35 221.5, i.e., the cross section of this energy dissipating element increases conically to the rear toward main frame  29  and is mounted on it with the cross-sectional shape of a horizontal rectangle. The mount may be in the form of weld seam S; likewise, the connection may be designed to be detachable. Energy dissipating element  25  may be provided with connecting plates at the connection points to main frame  29 . In the conically enlarged area, lateral reinforcements in the form of supporting ribs may also be provided. In the event of a collision of the rail vehicle with an energy exceeding the energy absorbing capacity of the buffer element ( 20 ,  21  and  22 ), the additional energy is absorbed by the deformation of energy dissipating element  25  as a deformable structure. To be able to utilize the total length of energy dissipating element  25 , a recess  30  is provided in transverse bar  31  so that the buffer element can pass through it. The structural design of energy dissipating element  25  according to the advantageous embodiment largely ensures that it will not collapse (bending deformation) even with eccentric induction of the impact energy but instead will deform by buckling axially. This deformation caused by compression causes a parallel folding of the walls of energy dissipating element  25  in the manner of a bellows shock absorber. 
     With the embodiments illustrated in FIGS. 2 and 3 and explained above, almost all of total length L over which the crash guard device extends can be utilized as active length. Thus on the whole, one and the same structure absorbs operating forces while at the same time containing the deformable structure for absorbing energy. Due to the greater available deformation distance, there is a lower force induction into the rail vehicle at the same energy dissipation. Thus, the locomotive structure can have a lighter design and likewise, all the built-in parts can be designed for lower shock loads. This yields total overall weight savings. As an alternative to the embodiment described above, energy dissipating element  25  may also be designed in the form of an insertion tube. 
     FIGS. 4 and 5 show two variants of flange  27  as seen from above. The flange is reinforced and optimized in terms of weight. The dimensions ultimately depend on the outside diameter of buffer box  20 . 
     FIG. 6 shows a true-to-scale (1:10) diagram comparing a conventional crash guard device (bottom) to a crash guard device according to an embodiment of the present invention (top) to permit a direct comparison of the active and inactive lengths. The most important dimensions of the two crash guard devices are also listed in the table in FIG.  7 . The percentage of the active length (deformation length) of crash element  25  has been increased by 72% in comparison with conventional devices. With regard to the total active length of the crash guard device (deformation length plus spring stroke) this yields a 56% improvement in comparison with conventional devices. 
     The crash guard device illustrated in FIG. 8 shows an advantageous embodiment of energy dissipating element (crash element)  25 . Slight kinks  38  (weak point) are provided in top side  36  and bottom side  37  in the end area of energy dissipating element  25  facing the buffer plate. First, this reduces the peak force at which deformation of energy dissipating element  25  occurs, so that in the event of a collision of the rail vehicle with an energy exceeding the energy absorbing capacity of energy absorbing element  32 , the rail vehicle is exposed to a lower maximum force induction. Second, this determines the location of the first fold, so that axial collapse is initiated at this location. The folding resistance is increased with additional lateral ribbing  39 , and an advantageous force-distance curve is predetermined. 
     FIG. 9 shows the cross section of the crash guard device from FIG. 8 along line A—A. Energy dissipating element  25  is designed with U-shaped side walls  35  so that the specified clearances can be maintained. Thus, for example, there is enough clearance (dotted line) for the arrangement of a compressed air tap  42  and its operation. In addition, due to the advantageous box-shaped design of energy dissipating element  25  with a rectangular cross section, which increases conically toward the rear in the direction of the main frame, it is ensured that the required free passage  41  beneath the buffer as specified according to the Eisenbahnbetriebsordnung [Railway Operating Regulations] (EBO) can be maintained in the area of the buffer. 
     FIG. 10 shows a top view of the crash guard device according to the present invention. Energy dissipating element  25  has the advantageous box-shaped design with a rectangular cross section, which is enlarged conically in the direction of the main frame and has U-shaped side walls  35 . Defined weak points  38 ,  38 ′ are provided on top side  36 , bottom side  37  and side walls  35  to induce axial collapse. Not shown are the parts of the buffer located in the interior of energy dissipating element  25 . Only the part of buffer plunger  21  and buffer plate  22  projecting out of the insertion area or buffer box  20  is shown here. 
     List of Reference Numbers 
       1  main frame 
       2  transverse bar 
       3  energy dissipating element (crash element) in the uncompressed state 
       4  energy dissipating element (crash element) in the compressed state 
       5 ,  6  buffer elements composed of 
       10  buffer plate 
       11  buffer box 
       12  inside part of buffer 
       7  lateral supporting ribs 
       20  insertion area or buffer box 
       21  buffer plunger 
       22  buffer plate 
       23  bottom part of the buffer box 
       24  hollow space in the energy dissipating element 
       25  energy dissipating element (crash element) 
       26  reinforced end piece of the buffer box 
       27  flange 
       28  head piece of the energy dissipating element 
       29  main frame or head piece 
       30  recess in transverse bar  31   
       31  transverse bar 
       32  energy dissipating element of the buffer 
       33  friction spring or spring collar 
       34  hydraulic capsule 
       35  U-shaped side wall of the crash element 
       36  top side of the crash element 
       37  bottom side of the crash element 
       38   38 ′ defined weak points 
       39  ribs to increase resistance to folding 
       40  guide ribs for the passage of the insertion area through the recess in the transverse bar 
       41  clearance beneath the buffer (specified by the Railway Operating Regulations) 
       42  compressed air tap with operating handle