Abstract:
The present invention relates to a pressure control valve including a valve housing which houses a valve seat in a housing opening, a valve closure member which is movable into abutment on the valve seat and adapted to interconnect or isolate pressure fluid channels connected to the valve seat, a bore in a guide element for the accommodation of the valve closure member which is axially movably supported on the wall of the valve housing. The valve closure member is attached in the guide element by way of a simplified press fit in conformity with the demands of automation. The assembly of the valve coil is simplified in addition.

Description:
TECHNICAL FIELD 
     The present invention relates to a pressure control valve, in particular, for slip-controlled automotive vehicle brake systems. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 5,460,437 discloses a pressure control valve closed in its basic position, including a valve housing which houses in a housing opening a valve seat on which a valve closure member abuts. The valve closure member is inserted as a separate component into an electromagnetically operable guide element which is supported axially movably along the wall of the valve housing. 
     Special adjusting measures are necessary to manufacture a valve of this type in order to ensure a preset press fit depth of the valve closure member in the guide element for reliably opening and closing the valve seat. Fixing of the valve closure member in the guide element is based on a precisest possible press fit in order to prevent undesirable loosening or deforming of both press fit parts. The assembly of the valve coil is impaired due to the close fit tolerances. The valve coil is not universally applicable due to the integration of the yoke ring in the valve housing. 
     An object of the present invention is to provide a pressure control valve of the type indicated which does not suffer from the mentioned shortcomings. 
    
    
     Further features, advantages and possible configurations of the present invention can be taken in the following from the description of an embodiment by way of several Figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal cross-sectional view of an electromagnetically operable pressure control valve. 
     FIG. 2 shows a section of FIG. 1 for illustrating the valve closure member during the press fit operation into the guide element. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiment of FIG. 1 shows a considerably enlarged total view of the pressure control valve, closed in the initial position, which is used especially for slip-controlled automotive vehicle brake systems. In the present embodiment, valve housing  14  of the pressure control valve is designed in cartridge-type construction and, by way of self-scaling of the hard valve housing material that is preferably steel, is press fitted into a valve accommodating member  20  that is softer in comparison. The valve housing  14  accommodates in its housing opening  21  a valve seat  12  bearing against which is a valve closure member  1  that is pressed into a guide element  6  under the effect of a compression spring  22 . 
     Guide element  6 , in the function of a magnetic armature, is guided axially movably along the wall of the housing opening  21 . For the electromagnetic actuation of the guide element  6 , a valve coil  15  is arranged on the valve housing  14  and is centered on a solenoid end plate  19  arranged between the valve coil  15  and the valve housing  14 . The valve housing  14  is closed on its sleeve-shaped stem portion on the side remote from the valve seat  12  by means of a press fitted and welded closure plug  16 . The closure plug  16  performs the function of a magnetic core in the present embodiment. The valve coil  15  is encompassed by a yoke ring  18  that contacts the solenoid end plate  19  at the end of its external peripheral surface, while the other end of the periphery&#39;s inside extends only up to roughly the step of the coil carrier  23 . 
     The result is an annular chamber  17  between the closure plug  16  and the coil  15  in the area of the coil carrier  23 , the said chamber  17  extending from the solenoid end plate  19  until the open end of the yoke ring  18 . In the present embodiment, the valve coil  15  together with the coil carrier  23  and the yoke ring  18  is an electric subassembly unit which permits independent handling and, by way of catching hooks fitted to it, is attached inside a cover (not shown) that includes electric and/or electronic components. These operations are effected before the subassembly unit is seated on the pressure control valve in the valve-accommodating member  20 . As has already been mentioned, the valve coil  15  is centered on the sleeve-shaped stem portion of the valve housing  14  by way of the solenoid end plate  19 . This is done by means of a conically stepped chamfer of the solenoid end plate  19  which extends in the direction of the annular chamber  17 . 
     The provision of an annular chamber  17  disposed between the valve coil  15  and the pressure control valve favorably permits the use of a valve coil  15  of uniform and, thus, universal application for pressure control valves of different overall dimensions (so-called standard coil) and, if desired and needed, renders it possible to make use of the free space provided by the annular chamber  17  to take up a sealing compound  31  which in addition to, or instead of, the proposed catching hooks  24 , ensures the desired engagement, attachment, and, optionally, also sealing of the valve coil  15  with respect to the housing assembly unit associated with the valve coil  15 . Further, the annular chamber  17  facilitates fitting the valve coil  15  to the pressure control valve. 
     The proposed stepped sleeve contour of the valve housing  14 , not only produces the best conditions for producing the necessary holding and sealing force within the valve-accommodating member  20 , but also produces a simple arrangement of filter elements  25 ,  26  which are configured as plate-type and ring-type filters in the present embodiment which reliably protect the pressure fluid channels  11  which open into the valve housing  14  in the horizontal and vertical directions so that the valve&#39;s inside parts will not become contaminated. In the present embodiment, the valve seat  12  being a separate, rotationally symmetrical component, is press fitted and/or calked until the stop from the direction of the closure plug  16  which closes the housing opening  21 . Manufacturing and fastening alternatives are possible, but they are not considered as a basic feature of the present invention. 
     Rather, the surprisingly simple clearance-free positioning of the valve closure member  1  on the guide element  6  will be referred to in the following. A special contour of the valve closure member  1  causes an absolutely reliable press fit in the guide element  6  during the press fit operation. For better illustration, FIG. 2 will be referred to in the following. 
     The embodiment of FIG. 2 shows in a considerably enlarged view the end of the guide element  6  remote from the valve closure member  1 , which end is known from FIG.  1  and is supported on an abutment surface  28 . A sleeve-shaped press fit tool  10  is aligned to the concentric straight-lined, i.e. not stepped, accommodating bore  27  for the valve closure member  1 . The valve closure member  1  is arranged between the press fit tool  10  and the guide element  6  with its truncated-cone-shaped chamfer  3  in contact with the accommodating bore  27 , thereby facilitating the press fit operation. Adjacent to the conical chamfer  3  is a stem portion  4  having a diameter which is conformed to the diameter of the bore  2  in the area of the accommodating bore  27  in a clearance-free manner. The stem portion  4  has a radially circumferential waist  5 . Waist  5  is directly followed by a cylindrical displacement member  7  having an outside diameter which is larger than the bore diameter in the area of the accommodating bore  27 . Following the displacement member  7  is a step in the shape of a collar  8  having an outside diameter which is considerably larger than the outside diameter of the displacement member  7 . 
     Remote from the first stop shoulder  9  on the collar  9  is a second stop shoulder  11  on collar  8  for the accommodation of the press fit tool  10 , as well as the spherical closure member  13  of the valve closure member  1  which is movable into abutment on the valve seat  12 . In this respect, FIG. 2 illustrates the alignment of the above-mentioned parts at the commencement of the press fit operation, to what end the press fit tool  10  is slipped over the closure member  13 , centered by it, if necessary, and moves into abutment on the second stop shoulder  30  in order to transmit the necessary press fit force onto the valve closure member  1 . 
     FIG. 1 shows the valve closure member  1  in a position in which the chamfer  3  extends into the accommodating bore  27  and, with the cylinder-shaped stem portion  4 , contacts the accommodating bore  27  so that, after having overcome the friction force, the valve closure member  1  moves into the accommodating bore  27  until abutment of the displacement member  7  on the guide element  6  with an almost constant effort of friction force. In this intermediate position, the waist  5  defined by the wall of the accommodating bore  27  forms an annular chamber into which the relatively soft material of the guide element  6  deforms as soon as the displacement member  7  enters into the guide element  6 . The press fit operation of the valve closure member  1  is completed as soon as the first stop shoulder  9  that follows the displacement member  7  will abut on the end surface of the guide element  6 . For the accommodation of the material of the magnetic armature deformed in the direction of the waist  5 , if required, the groove-shaped waist  5  may have larger dimensions than shown, or an additional waist  5  on the stem portion  4  may be provided. 
     It is possible due to the disclosed invention to obviate the need for previously necessary additional calking measures and securing means for the valve closure member  1  and to monitor the press fit depth of the valve closure member  1 . When the press fit operation is completed, the valve closure member  1  with its chamfer  3  will extend up to the area of a pressure compensating channel  29  which opens transversely to the valve closure member  1  and opens into the enlarged bore  2 .