Abstract:
A pneumatic spring (LUF) for a rail vehicle (SFZ), comprising two bellow rims (BF 1 , BF 2 ) mounted one above the other and interconnected by pneumatic-suspension bellow (LBA). One of the bellow rims (BF 1 ) comprises a groove (NUT) and the other rim (BF 2 ) comprises a counterpart (GGS) for the groove (NUT), which permit an automatic centering of the two bellow rims (BF 1 ,BF 2 ) in relation to one another in the transversal direction (Q) of the vehicle, if the pneumatic spring (LUF) fails.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority from PCT Patent Application No. PCT/AT2004/000249 filed Jul. 12, 2004, which in turn claims priority from Austrian Patent Application No. A 1084/2003 filed Jul. 15, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to rail vehicles and more particularly to a pneumatic spring for a rail vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     Usually, pneumatic springs LUF are arranged between a bogie DRE and a freight car body WKA of a rail vehicle. Such an arrangement or execution of a pneumatic spring as it is known in the state of the art is illustrated by way of example in  FIG. 1 . Naturally, the spring LUF can also be filled with a gaseous medium other than air, which is why the term “pneumatic spring” in this document quite generally refers to a gas spring. The known pneumatic spring LUF displays an air bellow LBA arranged between two bellow rims BF 1 , BF 2  usually made of steel. Pneumatic spring LUF is connected with the freight car body WKA or with the bogie DER via the bellow rims BF 1 , BF 2 . Usually, an emergency spring NOT is provided, for example, a rubber layer spring between pneumatic spring LUF and the bogie, where the two bellow rims BF 1 , BF 2  are usually made in the shape of plates.  
         [0004]     Transversal forces occurring during operation are absorbed by the pneumatic spring LUF and the emergency spring NOT, and a transversal movement of the freight car body WKA is usually limited by transversal buffers QPU, QPU′ that cooperate with a stop ANS ( FIG. 2 ). In known bogie designs, which employ pneumatic springs LUF with sliding plates GLP for emergency operation when the pneumatic spring LUF fails, its transversal rigidity is almost completely eliminated, as a result of which the transversal travel of the freight car body WKA in the hysteresis of sliding friction is undefined.  
         [0005]     This means that the upper and lower bellow rims BF 1 , BF 2  can, within the transversal sliding friction hysteresis, assume any undefined position with respect to each other ( FIG. 3 ), as a result of which the running performance of the rail vehicle SFZ will deteriorate or the permissible limitation profile can be impaired.  
         [0006]     It is therefore an object of the invention to minimize the transversal friction hysteresis as much as possible when the pneumatic spring fails.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     This problem is solved according to the invention with a pneumatic spring for a rail vehicle that comprises two bellow rims that are arranged above each other and that are connected with each other via an air bellow when in an assembled state. One of the bellow rims has a groove, while the other one of the bellow rims has a counterpiece for the groove for the purpose of the automatic centering in the lateral direction of the vehicle of the two bellow rims with respect to each other in case the pneumatic spring has failed.  
         [0008]     It is to the credit of the invention that it ensures a defined middle position of the two bellow rims with respect to each other even if the pneumatic spring fails because, in case of a failure of the pneumatic spring and the resultant settling or sinking of the upper bellow rim upon the lower bellow rim, the counterpiece and the groove can be made to engage each other. As a result of the cooperation of the groove with its counterpiece, one can greatly restrict the relative motion of the two bellow rims with respect to each other in the lateral direction of the vehicle. In the case of the invention-based solution, one can thus substantially eliminate the friction hysteresis by means of the self-centering groove and its counterpiece.  
         [0009]     In a preferred variant of the invention, the groove is arranged on the bellow rim that, when in the assembled state, lies above the other bellow rim, whereby for certain pneumatic spring systems, the alignment of the groove downward can also be advantageous. Furthermore, at least one of the bellow rims can display at least one sliding element.  
         [0010]     Advantageously, the groove displays an essentially triangular or trapezoidal cross-section. In particular, all sliding elements are made as level surfaces, as a result of which there can develop a relatively large-surface contact between the sliding surface and the countersurface, something that has a positive effect on the service life. Furthermore, the groove and the counterpiece can essentially be designed in a congruent fashion with respect to each other. Moreover, the groove can be bent, whereby the bend is advantageously adapted to the turnout movement. The counterpiece can basically have the shape of a cone, although it also can have some other shape.  
         [0011]     Optimized centering of the two bellow rims in case of a failure of the pneumatic spring can be achieved in the following manner: The apex of the groove and the counterpiece will extend essentially along a longitudinal midplane of its particular associated bellow rim. If the groove has a triangular cross-section, then sliding elements are disposed on a central portion of the facing surfaces of the upper and lower bellow rims, or one thereof, for the purpose of centering the two bellow rims in case the pneumatic spring has failed, whereas other, like sliding elements disposed on lateral portions of the facing surfaces of the upper and lower bellow rims, or one thereof, are provided to absorb vertical stresses.  
         [0012]     If the groove, on the other hand, has a trapezoidal cross-section, then there are provided sliding elements centrally on the upper and/or lower bellow rim for the purpose of absorbing vertical stresses in case the pneumatic spring has failed, whereas other sliding elements are provided laterally on the upper and/or lower bellow rim for the purpose of centering the two bellow rims. The functioning mode of the sliding plates is thus separated into a carrying row and a centering row. This separation of functions takes place as a result of the suitable choice of the tolerances and prevents the unnecessary jamming of the centering sliding plates.  
         [0013]     The service life is extended because the sliding elements display level sliding surfaces. The optimized design of the sliding plates facilitates a central air connection without which the sliding elements run over the air connection borehole, whereby the upper bellow rim, when in an assembled state, displays an air connection that is arranged centrally upon it, and the sliding elements, provided for the centering of the two bellow rims, can advantageously be made slanted on their corners that face toward the air connection, to prevent the opening from being covered up.  
         [0014]     The abovementioned problem is solved according to the invention also with a rail vehicle of the kind mentioned initially in that at least one pneumatic spring is arranged between the bogie and the freight car body. The alignment of the groove in the longitudinal direction (i.e., the direction of movement) facilitates a sliding action due to the turnout motion of the bogie when moving along an arc with simultaneous maintenance of the groove centering action.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings:  
         [0016]     FIGS.  1  to  3  are PRIOR ART elevation views of a rail vehicle representation showing a bogie and a freight car body of a rail vehicle with pneumatic springs;  
         [0017]      FIG. 4  is a basic sketch of a rail vehicle having the present invention;  
         [0018]      FIG. 5  is a partial top view of a bellow rim of the pneumatic spring of the present invention;  
         [0019]      FIG. 6  is a cross-section of the pneumatic spring of  FIG. 5 ;  
         [0020]      FIG. 7  is a top view of the pneumatic spring of  FIGS. 5 and 6  with an illustration of the possible operating states; and  
         [0021]     FIGS.  8  to  10  each show alternate embodiments of the pneumatic spring of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     FIGS.  4  to  10  illustrate the pneumatic spring of the present invention. According to  FIG. 4 , an invention-based rail vehicle SFZ has a bogie DRE and a freight car body WAK arranged above it. An invention-based pneumatic spring LUF is arranged between freight car body WAK and the bogie, below which the pneumatic spring is an emergency spring NOT, for example, a rubber layer spring. In case the pneumatic spring LUF fails, emergency spring NOT provides for the spring suspension of the freight car body WKA in the vertical direction, while to limit the maximum lateral deflection, one can provide a centrally disposed stop ANS whose lateral deflection is limited by two transversal buffers QPU, QPU′.  
         [0023]     Pneumatic spring LUF, as shown in  FIG. 6 , displays two mutually opposite bellow rims BF 1 , BF 2  that are connected with each other via a pneumatic bellow LBA. Such pneumatic springs LUF or pneumatic spring systems are known to the expert in many different forms and will therefore not be explained in any greater detail at this point. Furthermore, one of the two bellow rims BF 1  has a groove NUT, which preferably has a triangular or trapezoidal cross-section—see also  FIGS. 8-10 . The other bellow rim BF 2  displays a counterpiece GGS for the groove NUT, whereby the counterpiece GGS in a preferred embodiment of the invention is made congruent with the groove NUT. The counterpiece GGS is thus made as a wedge in case of a groove NUT with a triangular cross-section. Production can be simplified in the following manner: Bellow rim BF 2  and counterpiece GGS are made in one piece, although separate production with subsequent assembly of the counterpiece GGS and its bellow rim BF 2  would basically be possible.  
         [0024]     Very good centering action of the two bellow rims BF 1 , BF 2  and thus of pneumatic spring LUF in case of failure, can be achieved in the following manner: Groove NUT and counterpiece GGS are so arranged on their bellow rims BF 1 , BF 2  that the apex SCH of the groove NUT and the apex SCH′ of counterpiece GGS will extend essentially along a longitudinal midplane C of its particular associated bellow rim BF 1 , BF 2 . As a result, in case the pneumatic spring fails, one can ensure good engagement of the groove NUT with its counterpiece GGS.  
         [0025]     When pneumatic spring LUF is assembled, groove NUT is so arranged that the apex SCH of the groove NUT will extend essentially parallel to the longitudinal vehicle direction L. As a result of this measure and the arrangement of groove NUT on the upper bellow rim BF 1 , in case the pneumatic spring fails, one can assure self-centering of the rims with respect to each other. Basically, however, other embodiments are also conceivable, where the groove NUT is defined on the lower bellow rim BF 2  and the counterpiece GGS is defined on the upper bellow rim BF 1 . It is essentially the geometry of the pneumatic bellows and the bellow rims that will determine whether the groove is arranged on the upper or the lower bellow rim.  
         [0026]     Longitudinal movement of the two bellow rims BF 1 , BF 2  with respect to each other due to turnouts is facilitated by the sliding action of the counterpiece GGS in groove NUT. Any rotations occurring around the vertical axis V of the pneumatic spring LUF and the transversal shifts in the direction labeled Q, are absorbed by emergency spring NOT, while groove NUT will retain its transversally centered position ( FIG. 7 ). This means that very similar conditions obtain for the restriction calculation, both for pneumatic spring operation and for emergency operation—failure of pneumatic spring—something that has a particularly favorable effect on the design (width) of the freight car body WKA.  
         [0027]     Moreover, as a result of the wedge-shaped design of groove NUT and of counterpiece GGS, one can—in case of a lateral shift of the two bellow rims BF 1 , BF 2  with respect to each other in case of damage—guarantee the engagement of groove NUT and counterpiece GGS because counterpiece GGS, in case of the settling of the upper bellow rim BF 1 , can be “caught” by the sidewalls of the groove NUT. In that way, one can ensure the automatic centering of bellow rims BF 1 , BF 2  or of pneumatic spring LUF in the course of emergency operation. The transition phase from pneumatic operation to emergency operation, in particular, represents a critical situation, where groove NUT is optimized as a result of the abovementioned wedge-shaped design for this transition. This means that the two bellow rims BF 1 , BF 2  in case the pneumatic spring LUF has failed can automatically relatively center each other in all operating states (transversal travel, turnout, longitudinal travel and wobbling).  
         [0028]     By restricting the mobility of the two bellow rims BF 1 , BF 2  with respect to each other in the transversal direction Q, one can bring about an essential minimization of the lateral travel sliding hysteresis if the pneumatic bellow LBA should collapse.  
         [0029]     Furthermore, sliding plates GL 1 , GL 2 , GL 3 , GL 4  can be arranged on counterpiece GGS, while according to  FIG. 5 , two each of sliding plates GL 1 , GL 2 , GL 3 , GL 4  can be arranged on each wedge flank, which plates cooperate with the sidewalls of groove NUT. The segments ABS, ABS′ that adjoin the wedge flanks can also have sliding plates GL 1 , GL 2 , whereby the vertical stresses are introduced via these sliding plates GL 1 , GL 2 , while the sliding plates GL 3 , GL 4 , arranged on the wedge flanks, will serve primarily for the purpose of centering the two bellow rims BF 1 , BF 2  with respect to each other. There is thus a functional separation of sliding plates GL 1 , GL 2 , GL 3 , GL 4  into “carrying” and “centering.” 
         [0030]     If the groove has a trapezoidal cross-section, then sliding elements GL 3 , GL 4 , arranged in the middle segment, are provided to absorb vertical stresses in case pneumatic spring LUF should fail, while sliding elements GL 1 , GL 2 , arranged on a lateral segment ABS, ABS′, are provided to center the two bellow rims BF 1 , BF 2  ( FIGS. 9, 10 ).  
         [0031]     When the upper bellow rim BF 1  is in an assembled state, then a compressed air supply LFA, arranged centrally upon it, can include an opening OEF. The pneumatic air supply LFA can be arranged centrally by means of an arrangement of the sliding plates GL 3 -GL 6  upon counterpiece GGS, placed as far away from each other as possible, as a result of which, one can prevent a contact of the sliding plates GL 3 -GL 6  with the opening OEF.  
         [0032]     Moreover, the sliding elements GL 3 , GL 4 , GL 5 , GL 6 , provided for the centering of the two bellow rims BF 1 , BF 2  at their corners E 3 , E 4 , E 5 , E 6  facing toward opening OEF, can be advantageously slanted to prevent the opening OEF from being covered up ( FIGS. 5 and 7 ).  
         [0033]     Summarizing, one can say this: by virtue of the arrangement of groove NUT and counterpiece GGS on the upper or the lower bellow rim BF 1  or BF 2 , in case pneumatic spring LUF has failed, one exerts a centering effect upon these two parts in all possible operating states and thus, in case of a failure, bring about a clearly defined laterally centered state of the pneumatic spring LUF.  
         [0034]     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.