Abstract:
An electromagnet for actuating valves includes a sheath-like magnet housing encompassing a pole core forming a one-sided closure of the housing. The housing is connected to the pole core by an annular groove in its periphery, by an O-ring accommodated in the groove as a sealing element and by an annular groove in the magnet housing. The magnet housing forms bearing surfaces joined in positive fit to the inner walls of the annular groove and a sealing surface located on the O-ring.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electromagnet, particularly for actuating valves, with a sheath-like magnet housing. The housing encompasses a pole core on the actuation side of the electromagnet. An actuation member is accessible on the electromagnet and is movable by means of the armature of the magnet. The magnet housing is connected with the pole core in an area adjacent to the actuating side by means of a connection which is tightly fitting at least in that area. 
     BACKGROUND OF THE INVENTION 
     An electromagnet for actuating valves is disclosed in DE 195 04 185 A1. For this electromagnet to satisfy requirements for higher structural resistance and problem-free sealing of the magnet housing from the exterior environment, which sealing is particularly important during its use for the actuation of hydraulic valves, a costly structure with considerable manufacturing outlay generally results for conventional valves. 
     SUMMARY OF THE INVENTION 
     Objects of the present invention are to provide an electromagnet for actuating valves which is relatively simple and inexpensive to manufacture, particularly in view of its especially beneficial sealing and resistance properties. 
     The objects of the present invention are attained by an electromagnet having a connection between its magnet housing and pole core incorporating an annular groove formed between magnet housing and pole core in the periphery of the pole core. A removable sealing element is fitted in that groove. Another annular groove in the magnet housing also engages the sealing element. The connection forms contacts surfaces by engaging tightly and fitting on the interior walls of the pole core annular groove, as well as a contacting sealing surface encompassing the sealing element. 
     By virtue of this construction, with tightly fitting application of the frictional connection between the magnet housing and pole core, a problem-free sealing by contact of the annular groove of the magnet housing on the sealing element located in the adjacent annular groove is obtained simultaneously. As opposed to conventional electromagnets, wherein grooves forming inwardly aligned openings are uniformly distributed around the periphery of the magnet housing to form the connection, the connection obtained according to the present invention is without penetrating openings passing all the way through for a pressure-sealed sealing off of the housing. 
     The sealing element can be an O-ring, a gap seal or a suitable coating of the interior of the annular groove and/or of the pole housing in the area of the annular groove. 
     The manufacture is especially simple and low-cost when the magnet housing is a one-piece extrusion-molded part. That part includes an inwardly aligned open pole tube on its bottom, opposite the actuating end, open to the exterior of the magnet housing. The magnet housing is also the reverse side of the pole body. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawing, discloses a preferred embodiment of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Referring to the drawing which forms a part of this disclosure: 
     FIG. 1 is a side elevational view in section of an electromagnet connected with a multi-way valve according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates an electromagnet  1  and a multi-way valve  2  to be actuated by the electromagnet. Electromagnet  1  has a magnet housing  3  constructed by extrusion molding and forming one integral part. The magnet housing has the shape of a circular cylindrical beaker, from the bottom part  5  of which a central tubular pipe or pole tube  7  extends inward. The central tubular pipe is formed during the extrusion-molding procedure. Within magnet housing  3 , it forms a rear pole tube  7  of one integral piece with the housing. 
     Within magnet housing  3 , a spool or bobbin  9 , hereinafter spool  9 , incorporates a magnetizing coil  11 . The coil electrical connecting lugs  13  are guided outward through bottom openings  15  stamped out of bottom part  5  of magnet housing  3 . On the interior of pole tube  7  and on the interior of spool  9 , a thin walled tube  17  of nonmagnetic metal is engaged. The back or bottom of the tube  17  forms a guide for the armature piston  19 . From its front, outwardly tapered part, the thin tube  17  extends along the interior of spool  9  as far as its front end facing connecting lugs  13 . 
     Spool body  9  with magnetizing coil  11  and connecting lugs  13 , inserted into magnet housing  3 , is sprayed with insulating plastic. By means of built-in tube  17 , the sprayed plastic material surrounds the exterior of the magnetizing coil  11  and fills the space between the coil and the interior of magnet housing  3 . In this manner, an extruded connecting part  21  extends through bottom openings  15  as one integral spray-molded part formed on bottom part  5 . The connecting part closes bottom openings  15  as well as the exterior opening of tube  17 . This connecting part  21  also forms an integral plus part  23  for forming a contact with connecting lugs  13  of magnetizing coil  11 . Also, connecting part  21  is of such configuration that a surrounding annular groove  25  is formed in it to receive an O-ring  27 . 
     On the actuation end, an actuating pin  29 , connected with armature piston  19 , is accessible from the outside; and pole core  31  forms the actuation-side sealing of electromagnet  1 . Pole core  31  includes a widened-out flange part  33 , on the interior shoulder of which spool body  9  is supported. An encircling annular groove  35  extends into the exterior peripheral surface of flange part  33 , and accommodates a sealing element in the form of an O-ring  37 . Another annular groove  39  in magnet housing  3  is aligned with annular groove  35  such that magnet housing  3  contacts the interior walls of annular groove  35 , forming a tightly fitting connection between magnet housing  3  and pole core  31 . Since the groove  39  does not totally penetrate through the wall of magnet housing  3 , an encircling sealing surface is also obtained. The contact of the magnet housing  3  on the O-ring  37  in annular groove  35  forms a connection providing a pressure-tight sealing of magnet housing  3 . 
     Instead of the preferred O-ring  37 , a sealing arrangement of a different type could also be provided as the sealing element. For example, a gap seal arrangement or a coating with a sealing material could be provided. 
     A part of pole core  31  extends along the interior of spool body  9  in axial alignment with pole tube  7 , and has an annular groove accommodating an O-ring  41  for sealing off the tube  17  engaged on spool body  9 . This projecting part of pole body  31  terminates in a conical or tapered socket surface  43  facing pole tube  7 . Socket surface  43  is separated by an air gap  45  from the adjacent end of pole tube  7 . 
     For pressure compensation, an interior axial bore  47  penetrates or extends through magnet or armature piston  19 . Between armature piston  18  and the adjacent end of pole core  31 , an adhesive-resistant plate  49  of the conventional type is located. Actuation pin  29  engages with its contact surface on valve piston  51  of multi-way valve  2  which is to be actuated. Valve piston  51  is pre-biased by a compression spring  53  into contact with actuation pin  29 . 
     On the side of valve housing  54  predetermined for the application or connection of electromagnet  1 , multi-way valve  2  has a widened-out collar  55 . Magnet housing  3  is extended outward forming a free extension area  57  beyond groove  39 . Extension area  57  is beaded to accommodate the fastening of valve housing  54  to the exterior end surface  59  of pole core  31  with collar  55  of valve housing  54 . 
     Integration into one unit is obtained as a result of the overall spraying of spool body  9  by means of the incorporated tube  17 , to form the assembly comprising magnet housing  3 , spool  9  and tube  17 . Simultaneously, thin walled tube  17  is thus being guided and controlled. Tube  17  seals off the magnet from the exterior on the oil side, and in turn simultaneously offers armature piston  19  its guiding, and causes the magnetic disconnection. 
     With the sealed-off construction of electromagnet  1  provided by the annular groove  25  with O-ring  27  on connecting part  21 , oil-tight construction of electromagnet  1  in an oil chamber within a walled-off compartment or covering  61  is obtained. Since connecting part  21  projecting out of covering  61  is a plastic member and the other part of electromagnet  1  within covering  61  in the oil chamber is protected from exterior corroding influences, further exterior protection of electromagnet  1  against corrosion can be abandoned. Since tube  17  is supported on the exterior by the plastic material which has been sprayed on and on the interior of magnet housing  3  by spray-covered spool body  9 , electromagnet  1  can withstand increased interior pressure loads. 
     While a particular embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.