Patent Publication Number: US-2006017033-A1

Title: Electromagnetic valve

Description:
TECHNICAL FIELD  
      The present invention relates to an electromagnetic valve.  
      DE 199 28 750 A1 discloses an electromagnetic valve of the type of construction that is closed in the basic position, and the two tubular bodies thereof are welded or joined by folding to form the valve housing. The manufacturing effort needed for this operation is relatively high.  
      An object of the invention is to manufacture an electromagnetic valve of the type indicated hereinabove with least possible effort and structure so that there is no need for a welding or folding joint between the two tubular bodies. 
    
    
     BRIEF DESCRIPTION OF THE EMBODIMENTS  
       FIG. 1  is a longitudinal cross-section taken through an electromagnetic valve that is calked in a stepped bore of a valve-accommodating member.  
       FIG. 2  is a view of the electromagnetic valve of  FIG. 1  prior to the calking operation by means of a calking tool in the valve-accommodating member.  
       FIG. 3  is a longitudinal cross-section taken through an electromagnetic valve configured as a two-stage valve, having its further valve closure member guided directly in the first tubular body.  
       FIG. 4  is a longitudinal cross-section taken through an electromagnetic valve configured as a two-stage valve, having its further valve closure member guided in a spring stop separately inserted into the tubular body.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       FIG. 1  shows in a considerably enlarged view a longitudinal cross-section taken through an electromagnetic valve closed in its basic position, with a valve housing accommodating an armature  9 , a magnet core part  10 , a valve closure member  11  and a valve seat  12 , said housing being formed of a first and a second tubular body  1 ,  2 , with said two tubular bodies  1 ,  2  being joined in sections coaxially in each other with their facing open ends. The electromagnetic valve is secured in a block-shaped valve-accommodating member  3  into which the tubular section of the first tubular body  1  remote from the second tubular body  2  is inserted in a pressure-fluid tight manner. The tubular section of the second tubular body  2  remote from the first tubular body  1  carries a magnet coil  13  outside the valve-accommodating member  3 . Magnet coil  13  extends along the plug-shaped magnet core part  10 , which closes the end of the second tubular body  2  projecting from the valve-accommodating member  3 . Interposed between the magnet core part  10  and the valve seat  12  designed on the bottom of the first bowl-shaped tubular body  1  is the armature  9  carrying the valve closure member  11  and extending along the inside wall of the second tubular body  2 . Due to the effect of a compression spring  14  compressed between the magnet core part  10  and the armature  9 , the valve closure member  11  that is press-fitted as a ball into the end of the armature  9  closes the pressure fluid opening in the valve seat  12  in the initial position according to the drawing. The valve seat  12  is preferably formed in a stamping operation into the bowl bottom of the deepdrawn second tubular body  2  in a precise and nevertheless low-cost manner. The peripheral surface of the second tubular body  2  includes another opening  17  at the level of a transverse channel  15  penetrating the valve-accommodating member  3 , said opening  17  being made in a stamping operation exactly as opening  16  in the valve seat  12 . A ring filter  18  being supported in the stepped bore  5  on a bead  4  of the second tubular body  2  and below the opening  17  at the first tubular body  1  prevents the ingress of dirt into the armature chamber from the direction of the transverse channel  15 . A channel opening below the valve seat  12  into the stepped bore  5  is also equipped with a filter, if so desired or required.  
      The invention arranges that the section of the second tubular body  2  facing the first tubular body  1  is secured directly at the valve accommodating member  3  and that the section of the first tubular body  1  facing the second tubular body  2  is inserted into the second tubular body  2  and supported on an stop surface  6  of the second tubular body  2 . This renders possible a particularly simple, tight and safe connection of the first tubular body  1  and the second tubular body  2  within the valve-accommodating member  3  because the two tubular bodies  1 ,  2  with the single valve parts, which are pre-assembled therein so as to be operable, are simply press-fitted into the stepped bore  5  by means of a calking tool  19 , without the need for a welding or folding connection.  
      A surprisingly simple fixation of the tubular body  2  is achieved when the end of the second tubular body  2  facing the valve-accommodating member  3  includes a bead  4 , e.g. in the shape of a flange, that is directed radially outwards and fastened in a stepped bore  5  of the valve-accommodating member. An absolutely tight, undetachable attachment of the bead  4  in the stepped bore  5  is provided by the plastic deformation of material of the valve-accommodating member  3  by means of the calking tool  19  embracing the bead  4  at least along its edge.  
      To manufacture the stop surface  6 , the second tubular body  2  is provided with a housing step  7  having an inside diameter at the end of the joining portion  8  of both tubular bodies  1 ,  2  that is selected to be smaller than the outside diameter of the first tubular body  1  in the area of the joining portion  8 . Likewise the housing step  7  is manufactured at low costs by a plastic deformation of the second tubular body  2  in the end area of the joining portion  8  and preferably designed as an S-shaped double crank.  
      The first and second tubular bodies  1 ,  2  are comprised of thin-walled deepdrawn sleeves being interconnected by a press fit in the joining portion  8 .  
      The first, bowl-shaped tubular body  1  is supported with its end remote from the joining portion  8  in the second tubular body  2  in the stepped bore  5  of the valve-accommodating member  3  in a pressure-fluid tight manner, with the axial distance X between the bowl bottom of the first tubular body  1  and the bottom of the stepped bore  5  being smaller than the length L of the overlapping of both tubular bodies  1 ,  2  in the area of the joining portion  8  so that a sufficient overlapping of the two tubular bodies  1 ,  2  in the joining portion  8  is maintained in order to safeguard operability even if the press fit connection between the first and second tubular bodies  1 ,  2  loosens.  
      Different from the illustration in  FIG. 1 ,  FIG. 2  shows the electromagnetic valve during the assembly in the valve-accommodating member  3 , to what end the hollow-cylindrical calking tool  19  is slipped over the second tubular body  2  and, at the inside periphery, is supported with an inside shoulder  20  on the housing step  7  and with its outside shoulder  21  on bead  4 . The outside periphery of the calking tool  19  is provided with two housing steps  22 ,  23  adjacent to which is a conical portion  24  in the direction of the plane outside shoulder  21 . The result is a calking tool  19  decreasing in its outside diameter in the direction of the stepped bore  5  and displacing the material of the bore step of the valve-accommodating member  3  in the direction of the conical portion  24  by means of the second housing step  23  until finally likewise the first housing step  22  abuts on the non-deformed housing portion of the stepped bore  5 . At the moment when the first housing step  22  abuts on the non-deformable housing portion of the stepped bore  5 , the conical calked point at bead  4  is achieved, as illustrated in  FIG. 1 , which ensures a tight and rigid connection of the electromagnetic valve with the valve-accommodating member  3 .  
       FIGS. 3 and 4  show in each case a considerably enlarged view of a longitudinal cross-section taken through an electromagnetic valve that is closed in its basic position. The housing of said valve including an armature  9 , a magnet core part  10 , two valve closure members  11 ,  25  and two valve seats  12 ,  26  is formed of a first and a second tubular body  1 ,  2 , with the two tubular bodies  1 ,  2  being press-fitted in sections coaxially into each other with their open ends facing each other. It must be noted in addition that all other cited single parts are also arranged coaxially in a defined order within the valve housing.  
      The electromagnetic valve illustrated in  FIGS. 3, 4  is secured in a block-shaped valve-accommodating member  3  in which the tubular section of the first tubular body  1  that is remote from the first tubular body  1  is inserted so as to be pressure-fluid tight. The tubular section of the second tubular body  2  remote from the first tubular body  1  carries a magnet coil  13  outside the valve-accommodating member  3 . Said magnet coil  13  extends along the plug-shaped magnet core part  10  which closes the end of the second tubular body  2  projecting from the valve-accommodating member  3 . Interposed between the magnet core part  10  and the first bowl-shaped tubular body  1  is the armature  9  that carries the valve closure member  11  and is guided along the inside wall of the second tubular body  2 . Due to the effect of a compression spring  14  compressed between the magnet core part  10  and the armature  9 , the spherical valve closure member  11  provided with a tappet and press-fitted into the open end of the armature  9  will close the orifice-type opening  27  of the other valve closure member  25  in the basic position shown in the drawing, in whose bowl bottom the so-called further valve seat  26  is arranged that delimits the opening  27 . Valve seat  26  is shaped in the bowl bottom of the valve closure member  25 , preferably in a stamping operation in a low-cost and precise fashion.  
      The so-called further valve closure member  25  is composed of a sleeve bowl that is axially movable in the first tubular body  1 , deepdrawn from thin sheets and also thermally treated, if required. The sleeve&#39;s bowl bottom assumes the proper function of the valve closure member  25  (quasi in the function of a valve piston), which is pressed against the valve seat  12  fixed in the first tubular body  1  in a sealing fashion, what is done by the action of force of compression spring  14  in the basic position.  
      It can be taken from the embodiments of  FIGS. 3 and 4  that the inside diameter of the first tubular body  1  is adapted at least in sections to the outside diameter of the further valve closure member  25  for the purpose of a precise accommodation and guiding of the further valve accommodating member  25  corresponding with the valve closure member  11 . In this arrangement, it is required to provide a sufficiently sized clearance fit between the first tubular body  1  and the outside wall of the bowl-shaped valve closure member  25  to enable the further valve closure member  25  to move in a clamping-free manner and center itself at the valve seat  12 .  
      In  FIG. 3 , the valve seat  12  is designed as a massive valve plate, which is adapted to be separately handled and is shaped in a stamping operation directly in the bottom of the deepdrawn first tubular body  1  in a low-cost and precise fashion alternatively in  FIG. 2 .  
      In  FIGS. 3 and 4  the peripheral surface of the first tubular body  1  includes several openings  17  at the level of a transverse channel  15  that opens laterally into the valve-accommodating member  3 . Openings  17  are manufactured in a stamping operation exactly as the orifice-type opening  27  arranged in the bowl bottom of the valve closure member  25 . A ring filter  18  supported in the stepped bore  5  on a bead  4  of the second tubular body  2  and beneath the opening  18  at the first tubular body  1  prevents dirt from entering the valve housing from the direction of the transverse channel  15 . Of course, a channel opening into the stepped bore  5  below the valve seat  12  can also be provided with a filter, if desired or required.  
      In  FIGS. 3 and 4  the section of the second tubular body  2  facing the first tubular body  1  is fastened directly at the valve-accommodating member  3 , and the section of the first tubular body  1  facing the second tubular body  2  is inserted in a press fit into the second tubular body  2  and supported on a stop surface  6  of the second tubular body  2 . This renders possible a particularly simple, tight and safe connection between the first tubular body  1  and the second tubular body  2  within the valve-accommodating member  3  because the two tubular bodies  1 ,  2  along with the single valve parts, which are pre-assembled therein so as to be operable, are straightforwardly press-fitted into the stepped bore  5  by means of a calking tool, without requiring a welded or folded connection.  
      Further, a spring stop  28  is provided at the first tubular body  1  in both illustrations for supporting another compression spring  29 . According to the drawings, the further compression spring  29  is compressed between the spring stop  28  and the further valve closure member  25  so that the further compression spring  29  counteracts the compression spring  14  in a simple fashion, which latter is interposed between the armature  9  and the magnet core part  10 .  
      To be able to support the one end of the further compression spring  29  on the valve closure member  25  in a simple manner, the sleeve end of the valve closure member  25  remote from the bowl bottom is bent at angles in a radially outward direction towards the first tubular body  1  to form a collar  30 .  
      In the embodiment of  FIG. 3  the spring stop  28  is manufactured in a particularly inexpensive way directly by way of a shoulder of the first tubular body  1  constricted like a step in the deepdrawing process.  
      On the other hand, the spring stop  28  in the embodiment of  FIG. 4  is preferably designed as a thin-walled deepdrawn guiding sleeve that is inserted separately into the first tubular body  1 . At its bottom sleeve end, through which the further valve closure member  25  extends in the direction of the valve seat  12 , the guiding sleeve includes an edge cranked in the direction of the sleeve&#39;s longitudinal axis, on which edge the one end of the compression spring  29  abuts. In the area of overlapping of both tubular bodies  1 ,  2 , the sleeve-shaped spring stop has a guiding portion that abuts on the inside wall of the first tubular body  1  in a clearance-free manner in order to properly center the spring stop  28  in the valve housing.  
      Instead of the guiding sleeve, it would alternatively be feasible to design the spring stop  28  as an insert member in the shape of a flat disc.  
      To sum up, it can now be stated that the adept dimensioning of the electromagnetic valve in the area of the first tubular body  1  achieves optimal structural conditions in order to configure the electromagnetic valve in a particularly space-saving manner as a two-stage valve by using a smallest possible number of easy-to-make components.  
      This is because the electromagnetic valve includes a supply restriction stage formed of the valve closure member  11  and the further valve seat  26  as well as a main stage. Upon electromagnetic energization of the armature  9 , the supply restriction stage is effective due to the valve closure member  11  lifting from the (further) valve seat  26 , with the result that the orifice-type opening  27  is released by means of the valve closure member  11 . The unrestricted main stage is only effective when the supply restriction stage is opened and, in the balance of forces, the valve opening force exerted by the compression spring  29  exceeds the hydraulic forces that act on the valve closure member  25  so that the valve closure member  25  mainly formed by the bowl bottom lifts from the valve seat  11  by the action of the compression spring  29 , whereby the large flow cross-section of opening  16  is opened.