Patent Publication Number: US-2016222992-A1

Title: Brake Cylinder

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT International Application No. PCT/EP2014/071717, filed Oct. 10, 2014, which claims priority under 35 U.S.C. §119 from German Patent Application No. 10 2013 016 890.2, filed Oct. 11, 2013, the entire disclosures of which are herein expressly incorporated by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to a brake cylinder for a vehicle brake, in particular for the brakes of a commercial vehicle. 
     Brake cylinders of this kind are known in relevant forms in the prior art. 
     A conventional wheel brake for a vehicle comprises, inter alia, a service brake by which a braking force required for braking the vehicle when driving is produced. Especially when it is pneumatically actuated, a service brake has a brake cylinder which produces the service brake application force via a brake caliper. The brake cylinder includes a piston rod which acts, for example, on a linkage to actuate the brake. According to the prior art, a brake cylinder generally has at least two housing parts, wherein both housing parts are clamped together with a diaphragm serving as a piston by a clamp to form the brake cylinder housing with the integrated diaphragm or piston. 
     U.S. patent publication no. U.S. Pat. No. 2,541,205 A1 discloses a one-piece clamp which clamps two tubular or cylindrical components together in a fluidtight manner. For this purpose, the two ends of the tubular or cylindrical components each have a wedge-shaped thickened portion or wedge-shaped collar on their side facing the clamp. Together, the two collars form a cross section in the form of a V belt, over which the clamp according to the invention engages. The clamp is designed as a screw clamp, i.e. the clamping force of the clamp is produced nonpositively by means of a screw/nut joint arranged tangentially in relation to the circumference. 
     U.S. Pat. No. 4,960,036 discloses a clamp divided into two in a radial direction, by which the housing halves of a brake cylinder and a diaphragm are clamped together. On their open sides, the housing halves each have a collar or a thickened portion. The clamping force of the two-part clamp is produced nonpositively by two screw/nut joints each arranged tangentially in relation to the circumference. 
     U.S. patent no. U.S. Pat. No. 5,193,432 A furthermore discloses a one-piece clamp, with which the intention is to provide a tamperproof brake cylinder. The clamp is produced nonpositively by a radially arranged screw/nut joint. 
     In each case, the disadvantage with the abovementioned prior art is that the respectively disclosed clamp does not completely surround the two housing components since, by virtue of its operation, a gap must be left between the ends of the clamp in order to produce an appropriate clamping force. This produces a discontinuous force profile which is nonuniform over the entire circumference of the clamp. The clamped components are therefore subject to surface pressures which are of considerable magnitude locally and are at least not conducive to the service life of the components. Moreover, a screw/nut joint takes up a considerable amount of installation space, which is often not unlimited in the restricted installation space zones of a brake cylinder. 
     In addition, U.S. patent publication no. US 2007/0017757 A1 presents a tamperproof spring cylinder in which two housing parts and a diaphragm are clamped together. The clamping force required for this is produced positively by snap hooks, which are arranged in a pattern on the circumference of one of the two housing parts. The snap hooks latch into corresponding depressions arranged in the other housing part to be clamped. In the solution disclosed in U.S. patent publication no. US 2007/0017757 A1, there is no explicit mention of a clamp or additional parts that produce the clamping function. 
     The disadvantage with the solution according to U.S. patent publication no. US 2007/0017757 A1 is the integration of the clamping function into the housing ends. To achieve this, at least one housing part has to be produced from a material with good forming characteristics. Moreover, the solution disclosed requires a complex assembly method and tool. Owing to the geometry at the housing end of at least one housing part, tight forming radii are required, which can lead to microcracks in the surface protection coating, in which case there is therefore the risk of the premature onset of corrosion. 
     It is therefore the underlying object of the invention to provide a brake cylinder which at least partially overcomes the abovementioned disadvantages. 
     In a particularly preferred embodiment of the invention, the positive clamped joint is implemented in a manner which is simple in terms of design by the latching of a clamping ring on the housing upper side and a clamping ring on the housing lower side. 
     In another preferred embodiment of the invention, the clamping ring associated with the housing lower part has openings, wherein the openings are arranged uniformly in a regular pattern on the circumference of the clamping ring associated with the housing lower part, with the result that an opening advantageously alternates with a circumferential portion without an opening. 
     In another preferred embodiment of the invention, the clamping ring associated with the housing upper part has snap hooks, wherein the snap hooks are arranged uniformly in a regular pattern on the circumference of the clamping ring associated with the housing upper part, with the result that a snap hook alternates with a circumferential portion without a snap hook in a structurally simple manner. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a section through a brake cylinder according to an embodiment of the invention; 
         FIG. 2  shows an enlarged detail in section of the brake cylinder according to  FIG. 1 ; 
         FIG. 3  shows a three-dimensional view of a brake cylinder according to an embodiment of the invention; 
         FIG. 4  shows an exploded view of a brake cylinder according to an embodiment of the invention, wherein the exploded view is limited to the housing components and a diaphragm. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A brake cylinder  1  is shown fully in section in  FIG. 1 . The brake cylinder  1  has a brake cylinder housing  2 , which is divided into a housing upper part  3  and a housing lower part  4 . 
     The housing upper part  3  has a frustoconical basic geometry and, during the operation of the brake cylinder  1 , is supplied with a pressurized fluid. The brake cylinder  1  is operated with compressed air as the fluid. 
     The housing upper part  3  furthermore has fluid-line connections  5 ,  6  for supplying the brake cylinder with fluid. In order to provide a plurality of possible connections in the case of problems with installation space, one fluid-line connection  5  is implemented vertically on the end face and the other fluid-line connection  6  is implemented horizontally by a protrusion  7  on the housing upper part  3 . Since, insofar as the brake cylinder  1  is operated with a gaseous fluid—e.g. compressed air—it is operated as a single-acting cylinder, one fluid-line connection  5 ,  6  in each case is supplied by the fluid inlet line (not shown), while the other fluid-line connection  5 ,  6  in each case is provided with a vent (not shown). Moreover, the housing upper part  3  has an encircling collar  8  on its upper side. 
     The housing lower part  4  has a housing bottom  9 . The housing bottom  9  has at least two securing means, here embodied as threaded bolts  10 ,  11 —purely by way of example—by which the brake cylinder  1  is secured on a brake (not shown). Here, by way of example, the threaded bolts  10 ,  11  are secured on the housing bottom  9  by fusion welding. However, it is also possible to secure the threaded bolts  10 ,  11  on the housing bottom  9  by some other joining method. The housing bottom  9  furthermore has an opening  12 . Inserted into the opening  12  is a seal  13 , which forms a sealing bellows  14  in the vertical direction, wherein the sealing bellows  14  extends in the direction of the housing other part  3 . Here—purely by way of example—the sealing bellows  14  is designed as a folding bellows. The seal  13  furthermore centers a compression spring  23 . The housing lower part  4  furthermore has a collar  15  on its open side. 
     The brake cylinder  1  furthermore has a diaphragm  16 . On its outer edge, the diaphragm  16  has a bead  17 . The bead  17  has a wedge-shaped basic cross section, wherein the wedge flanks  18 ,  19  of the bead hug the respective collars  8 ,  15  of the housing upper part  3  and the housing lower part  4 , thus producing a sealing function between the housing upper part  3  and the housing lower part  4 . The diaphragm  16  has a plurality of annular depressions  20 , which are used to center a pressure plate  21 . The diaphragm  16  is preferably produced from a rubber-elastic material. 
     The pressure plate  21  has a circular groove  22 , by which a compression spring  23  is centered and/or positioned in the housing upper part  3 . Purely by way of example here—the compression spring  23  has a circular wire cross section and—likewise purely by way of example—a barrel-shaped basic geometry. In the single-acting brake cylinder  1 , the compression spring  23  brings about the return of a piston rod  24 . At its end associated with the housing upper part, the piston rod  24  forms a conical head  25  and rests by the conical head  25  against the pressure plate  21 . At its end associated with the housing upper part, the sealing bellows  14  forms a sealing bead  26 , wherein the sealing bead  26  is fixed under the conical head  25  of the piston rod  24  by a clamping ring  27 . The piston rod  24  passes through the sealing bellows  24  and a central opening  28  in the seal  13 . At its end associated with the housing lower part, the piston rod  24  has a pressure piece  29 , which—purely by way of example here—is screwed centrally into the piston rod  24 . As an alternative, other joining methods are also possible. In the installed state of the brake cylinder  1 , the pressure piece  29  makes contact, for example, with a linkage (not shown), by which a brake (not shown) is applied. 
     The region of the joint between the bead  17  of the diaphragm  16  and the respective collars  8 ,  15  of the housing upper part  3  and the housing lower part  4  are readily visible in  FIG. 2 . 
     The region of the joint has a clamping ring  30  associated with the housing lower part, said ring having a substantially J-shaped cross section. The inner side  31  of the vertical leg  32  of the clamping ring  30  associated with the housing lower part hugs the outer edge  33  of the bead  17  of the diaphragm  16 . The inner side  35  of the angled leg  34  of the clamping ring  30  associated with the housing lower part hugs the collar  15  of the housing lower part  4 . For this purpose, the collar  15  has a corresponding flat  36 . The clamping ring  30  associated with the housing lower part furthermore has openings  37  in its vertical leg  32 . The openings  37  are arranged uniformly in a regular pattern on the circumference of the clamping ring  30  associated with the housing lower part, with the result that an opening  37  alternates with a circumferential portion without an opening  37 . The opening  37  preferably has a rectangular cross section. The dimensions of the openings  37  are preferably the same for all the openings  37  situated on the circumference of the clamping ring  30  associated with the housing lower part. 
     The region of the joint furthermore has a clamping ring  38  associated with the housing upper part, which has a J-shaped cross section rotated substantially through 180° in the installed position. The inner side  39  of the vertical leg  40  of the clamping ring  38  associated with the housing upper side hugs the outer side  41  of the clamping ring  30  associated with the housing lower part. The inner side  43  of the angled leg  42  of the clamping ring  30  associated with the housing upper side hugs the collar  8  of the housing upper part  4 . For this purpose, the collar  8  has a corresponding flat  44 . The clamping ring  38  associated with the housing upper part furthermore has snap hooks  45  on its vertical leg  40 . The snap hooks  45  are arranged uniformly in a regular pattern on the circumference of the clamping ring  38  associated with the housing upper part, with the result that a snap hook  45  alternates with a circumferential portion without snap hooks  45 . The snap hook  45  has a geometry and dimensions corresponding to the opening  37 . 
     The snap hook  45  is produced by cutting the vertical leg  40  and then pushing out the tab  46  formed by the cutting process in the direction of the inner side  39  of the vertical leg  40  of the clamping ring  38  associated with the housing upper side. In this case, the free end  47  of the tab  46  is oriented in the direction of the housing upper part  3  and engages in the corresponding opening  37  in the clamping ring  30  associated with the housing lower part. 
     As a result, the housing upper part  3  and the housing lower part  4  are positioned and fixed one upon the other positively, and the brake cylinder housing  2  is formed, by latching the clamping ring  30  associated with the housing lower part and the clamping ring  38  associated with the housing upper part while simultaneously exerting a clamping or sealing force on the bead  17  of the diaphragm  16 . 
     The snap joint is preloaded by the bead  17  of the diaphragm  16  since the rubber-elastic material pressed in by the housing upper part  3  and the housing lower part  4  exerts a corresponding counterforce on the housing upper part  3  or clamping ring  38  associated with the housing upper part and on the housing lower part  4 . 
     Readily visible in  FIG. 3 , there are, in particular, the clamping ring  38  associated with the housing upper part and the tabs  46  thereof, which are arranged in a regular pattern on the circumference of its vertical leg  40 , and the protrusion  7  of the housing upper part  3 . 
     A method of assembling the housing components  3 ,  4 ,  30 ,  38  and the diaphragm  16  is shown in  FIG. 4 . Components which are situated or arranged in the interior of the housing after assembly are not shown for greater clarity, and are also not mentioned or dealt with explicitly. It is assumed below that the housing upper part  3  and the housing lower part  4  are each preinstalled in the interior of the housing with all components required for the operation of the brake cylinder  1 . 
     First of all, the clamping ring  30  associated with the housing lower part and the housing lower part  4  are provided and placed on a fixed annular support (not shown). 
     Here, the housing lower part  4  rests by the flat  36  thereof on the inner side  35  of the angled leg  34  of the clamping ring  30  associated with the housing lower part. On the other hand, the clamping ring  30  associated with the housing lower part rests by its angled leg  34  on the fixed annular support, which can be designed as the lower part of an assembly tool, for example. 
     In a further step, the diaphragm  16  is placed on the collar  15  of the housing lower part  4 , and the housing upper part  3  is then placed by its collar  8  on the diaphragm  16 . 
     In a final step, the clamping ring associated with the housing upper part is then positioned correctly and pressed onto the flat  44  of the housing upper part  3  by a suitable annular tool (not shown) until the free ends  47  of the tabs  46  of the clamping ring  38  associated with the housing upper part, said free ends being designed as snap hooks  45 , latch into the openings  37  in the clamping ring  30  associated with the housing lower part. 
     LIST OF REFERENCE SIGNS 
     
         
           1  brake cylinder 
           2  brake cylinder housing 
           3  housing upper part 
           4  housing lower part 
           5  fluid-line connection 
           6  fluid-line connection 
           7  protrusion 
           8  collar 
           9  housing bottom 
           10  threaded bolt 
           11  threaded bolt 
           12  opening 
           13  seal 
           14  sealing bellows 
           15  collar 
           16  diaphragm 
           17  bead 
           18  wedge flank 
           19  wedge flank 
           20  annular depression 
           21  pressure plate 
           22  circular groove 
           23  compression spring 
           24  piston rod 
           25  conical head 
           26  sealing bead 
           27  clamping ring 
           28  central opening 
           29  pressure piece 
           30  clamping ring associated with the housing lower part 
           31  inner side 
           32  vertical leg 
           33  outer edge 
           34  angled edge 
           35  inner side 
           26  flat 
           37  opening 
           38  clamping ring associated with the housing upper part 
           39  inner side 
           40  vertical leg 
           41  outer side 
           42  angled leg 
           43  inner side 
           44  flat 
           45  snap hook 
           46  tab 
           47  free end 
       
    
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.