Abstract:
The present invention relates to an electromagnetic valve, the spring thereof being arranged outside the flow route that can connect the pressure fluid inlet to the pressure fluid outlet in order to reduce the flow resistance, to what end a stop is inserted in the valve housing remote from the flow route, on which stop the end of spring facing away from the second valve closure member rests.

Description:
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0001]      FIG. 1  shows a considerably enlarged longitudinal cross-sectional view of an electromagnetic valve including a one-part deepdrawn valve housing  1  of thin-walled design that accommodates a separate retaining collar  2  seated on the outside periphery of the valve housing and attached by means of laser welding, said retaining collar being made by non-cutting shaping, e.g. as a cold-heading part. The outside periphery of the substantially disc-shaped retaining collar  2  is configured as a calking punch so that it is press-fitted with its undercut extending along the periphery with the ready-made valve housing  1  in a stepped accommodating bore of a block-shaped valve carrier  4 . The soft material of the valve carrier is displaced during the pressing operation into the undercut for fastening and sealing purposes. Above the retaining collar  2 , the open end portion of the sleeve-shaped valve housing  1  is closed by means of a plug  14  additionally assuming the function of a magnet core. Likewise plug  14  is a low-cost cold-heading part that is manufactured with a sufficient rate of precision and laser-welded at its outside periphery with the valve housing  1 . Disposed below the plug  14  is a magnet armature  15  being manufactured equally very inexpensively from a round or many-sided profile by means of cold-heading or extruding operations, respectively. Magnet armature  15 , under the effect of a compression spring  16 , closes in the valve&#39;s basic position a first valve passage  5  arranged in a second valve closure member  8  by means of the first valve member  7  that is fitted to the tappet-shaped extension of the magnet armature  15 . To this end, the first valve closure member  7  is expediently fitted as a hemisphere at the tappet portion that is attached in a bore of the magnet armature  15  by means of self-calking. The second valve closure member  8  is substantially designed as a bowl-shaped deepdrawn part acted upon in the valve&#39;s closing position of the first valve closure member  7  by the effect of a spring  17 .  
         [0002]     However, due to the effect of the compression spring  16  interposed between the plug  14  and the magnet armature  15 , the bottom of the bowl-shaped second valve closure member  8  acting as a valve closure means remains in the valve&#39;s basic position shown in the drawings on a second valve passage  6  provided in the bottom end of the valve housing  1 . The cross-section of said valve passage that can be opened in response to the hydraulic differential pressure is considerably larger than the opening cross-section at the first valve passage  5  that can be opened electromagnetically.  
         [0003]     Spring  17  is supported at an edge of the second valve closure member  8  configured as a sleeve-type piston and being horizontally penetrated by punched transverse bores  22 .  
         [0004]     To accommodate and seal the valve housing  1  in the bore step  11 , the valve housing  1  is decreased in diameter in the area of the bore step  11  and equipped with a sealing ring  10  so that between the valve housing  1  and the bore step  11 , leakage flow is prevented between the pressure fluid inlet  13  opening horizontally into the valve housing  1  and the pressure fluid outlet  19  arranged below the valve housing  1 . The pressure fluid inlet  13 , which is basically illustrated as a transverse channel in the valve carrier  4 , is continued through the annular filter  12  disposed in the hollow space  20  of the valve carrier  4  to the punched transverse bore  21  in the valve housing  1  so that pressure fluid on the inlet side is applied directly to the second valve closure member  8 , whose transverse bores  22  arranged in the horizontal plane to the transverse bore  21  ensure a low-resistance flow route without any rerouting and, hence, leading directly to the first valve member  7 .  
         [0005]     In addition, the electromagnetic valve is characterized in that the spring  17  is arranged outside the flow route that can connect the pressure fluid inlet  13  to the pressure fluid outlet  19 . For this purpose, stop  3  is inserted remote from the flow route into the valve housing  1 , at which stop the end of spring  17  remote from the second valve closure member  8  is supported. Consequently, spring  17  is not arranged in the flow route but above the transverse bores  21 ,  22  at stop  3 . Stop  3  is secured to a housing step  19  of the valve housing  1  to this end. Said housing step  19  is arranged above the transverse bore  21  extending through the valve housing  1 . Stop  3  is designed as a sleeve bowl widely opened in the bowl bottom and having an opening in which the second valve closure member  8  is guided and centered in the direction of the valve seat member  27 . The one end of spring  17  is supported on the bowl bottom of stop  3 . The bowl edge remote from the bowl bottom is angled off towards the inside wall of the valve housing  1 . The result is that an annular chamber  25  accommodating spring  17  is positioned between the outside periphery of the sleeve bowl and the inside wall of the sleeve-shaped valve housing  1  and constitutes a permanent pressure fluid communication between the pressure fluid inlet  13  and a magnet armature chamber  26  by way of pressure compensating openings  18  arranged in the valve housing  1  and at the periphery of the sleeve bowl. Stop  3  and valve sleeve  1  consist of a deepdrawn thin sheet wherein the pressure compensating openings  18  are punched or impressed. Especially small valve parts that can be manufactured at low cost and with precision are achieved thereby.  
         [0006]     The one-part valve housing  1  is designed as a stepped, thin-walled drawn sleeve whose open end remote from the second valve passage  6  is closed by a plug  14  effective as a magnet core and being designed as a cold-heading or extruded part allowing low-cost and precise manufacture. For the mechanical relief of the valve housing  1 , the second valve passage  6  is provided in a disc-shaped or sleeve-shaped valve seat member  27  which is retained in a snug fit on the inside wall of the valve housing  1 . The valve seat member  27  is composed of a wear-resistant metal. Its total height is chosen such that the second valve closure member  8  with its diametral transverse bores  21  rests at the level of the diametral transverse bores  22  of the valve housing  1 , irrespective of whether the valve closure member  8 , being in its closing position according to the drawing, closes the large second valve passage  6  or is lifted therefrom. Therefore, the two transverse bores  22  in the valve housing  1  are increased in their diameter compared to the passages of the transverse bores  21  positioned in the second valve closure member  8  at least by the stroke of the second valve closure member  8  so that the transverse bores  21  are always overlapping the transverse bores  22  even in the hydraulically initiated open position of the second valve closure member  8  for the purpose of a flow routing that is without any deviation and has a low resistance to the greatest degree possible.  
         [0007]     The second valve closure member  8  is configured as a sleeve bowl whose bowl bottom accommodates the first valve passage  5  cooperating with the second valve closure member  7 . Close to the bowl bottom, transverse bores  22  penetrate the peripheral surface of the sleeve bowl and are positioned in the horizontal plane of the transverse bore  21  to provide a flow route that is free from rerouting, if possible. Opposite to the bowl bottom, an edge is provided at the sleeve bowl that is angled-off in the direction of the sleeve-shaped stop  3  and on which the second end of spring  17  remote from stop  3  is supported. Designing the stop  3  as a sleeve portion radially spaced from the inside wall of the valve housing  1  includes the advantage that the forces that act from the retaining collar  2  on the valve sleeve  1  during the press fit operation of the electromagnetic valve are accommodated by the annular chamber  25  in the case of a deformation of the valve housing  1  and do not act on the second valve closure member  8 . This prevents the second valve closure member  8  from being damaged and jammed, even if relatively significant tolerance variations occur. The sleeve bowl is of light weight, small and inexpensive, and is manufactured preferably by deepdrawing from a thin sheet. 
     
    
       [0008]     Different from  FIG. 1 ,  FIG. 2  discloses another suitable design of some component parts. The electromagnetic valve according to  FIG. 2  differs basically from the valve construction according to  FIG. 1  by the second valve closure member  8  and the valve seat member  27  being configured as solid turned parts and/or cold-heading parts.  FIG. 2  shows the second valve closure member  8  as a slim piston part that is conically turned at its bottom end and manufactured inexpensively from free-cutting steel. Said conical end normally bears against the conical sealing seat of the hollow-cylindrical valve seat member  27  which, when required, exactly as the valve closure member  8  can be furnished with a surface hardening in the area of the sealing surfaces. Accommodation of the tappet portion within the second valve closure member  8  (cf.  FIG. 1 ) is deliberately omitted in the design of the electromagnetic valve according to  FIG. 2  because this would necessitate an unnecessary quantity of metal removed for manufacturing the valve closure member  8 .  
         [0009]     Even if not all the features shown in  FIG. 2  have been explicitly described in the previous paragraph, they correspond to the features explained in  FIG. 1 .