Patent Publication Number: US-9852864-B2

Title: Electromagnetic switching device

Description:
The present invention relates to an electromagnetic switching device. In particular, the present invention relates to an electromagnetic switching device which is provided with a bearing sleeve, which accommodates a magnetic armature, a bearing and a pressure pin guided via the bearing. 
     The present invention also relates to a method for manufacturing an electromagnetic switching device. 
     BACKGROUND 
     In known electromagnetic switching devices, the seal is established, for example, by introducing O ring seals or by media-tight extrusion coating of the coil. One disadvantage of the arrangements known from the prior art is that an increased assembly complexity and thus also higher costs are caused by the additionally required components. The risk, which should not be underestimated, also exists that fluctuations arising during the injection molding process may result in leaks. 
     An electromagnetic adjusting device is known from DE 10 2006 015 233 B4, in which the yoke section and the core section are implemented as a yoke/core section manufactured as a single piece, whereby the complex axial centering of the components relative to each other is eliminated. A magnetic short circuit is generated between the core and the yoke, which has only a limited impact on efficiency, due to additional geometric arrangements, but does not mitigate this impact entirely. The bearing unit in this case is mounted in the housing. 
     In DE 10 2007 061 862 A1, a bearing sleeve is integrated into the switchable magnet arrangement with the aid of a welding method. All other parts are inserted into an injection mold, and extrusion-coated with a plastic compound, so that they are held fixedly against each other. A pressure compensation is to be implemented in the magnet without any compensating bores in the armature piston. For this purpose, it is proposed that the armature and/or the yoke and/or the conical guiding element and/or the bearing is/are surrounded by a magnetically conductive, media-permeable material. 
     As a result, the devices according to the prior have an increased assembly complexity. Due to the injection molding process and the media-permeable material, a complete and secure sealing of the magnet against the surroundings may not be achieved. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an electromagnetic switching device which is easy and economical to manufacture and which nevertheless has the necessary tightness against the oil-wetted interior of the magnet and the surroundings. 
     Another alternate or additional object of the present invention is to provide a method for manufacturing an electromagnetic switching device which is simple and cost-effective. 
     An electromagnetic switching device includes at least one magnetic armature, a yoke, a pressure pin which is movably guided along an axis in a bearing, and a bearing sleeve. The bearing sleeve accommodates at least the bearing and the magnetic armature. 
     According to the present invention, at least the electromagnet casing and the bearing sleeve are formed as a one-piece component from a material with the aid of a forming process, preferably with the aid of a deep drawing technique. All other components which are still present in the electromagnetic switching device are inserted into the component of a one-piece design, which includes at least the electromagnet casing and the bearing sleeve. At least the magnetic armature and the bearing are inserted into the bearing sleeve, in that the pressure pin is guided along an axis. A coil, a coil carrier, an intermediate segment and, if necessary, a pole core and/or a yoke are inserted between the electromagnet casing and the bearing sleeve. A sealing function is integrated into the bearing sleeve, whereby additional components forming the sealing function are eliminated. It is also no longer necessary to extrusion coat the components with the aid of an injection molding process. As a result, the assembly complexity and the risk of leaks, which may arise due to the injection molding process, are reduced. 
     In a first specific embodiment of the electromagnetic switching device, the electromagnet casing, the bearing sleeve and the pole core are formed together as a one-piece component from a material. The pole core is formed on the outer diameter of the bearing sleeve. In this specific embodiment, the yoke is mounted as a separate component between the bearing sleeve and the electromagnet casing. 
     In a second specific embodiment of the electromagnetic switching device, the electromagnet casing, the bearing sleeve, the yoke and the pole core are formed together as a one-piece component from a material. The pole core and the yoke are formed on the outer diameter of the bearing sleeve. A yoke plate abuts the yoke formed on the bearing sleeve. 
     The magnetic armature may be supported and/or guided in the inside of the bearing sleeve. This may take place, for example, with the aid of a friction bearing which is provided between the magnetic armature and the inside of the bearing sleeve. A magnetically non-conductive anti-friction layer may likewise be provided between the magnetic armature and the inside of the bearing sleeve. 
     In a third specific embodiment of the electromagnetic switching device according to the present invention, the electromagnet casing and the bearing sleeve are formed together as a one-piece component from a material. The pole core and the yoke are mounted as separate components on the outer diameter of the bearing sleeve. 
     In the specific embodiments in which the pole core and/or yoke is/are mounted as separate components on the outer diameter of the bearing sleeve, they are preferably deep-drawn, extruded, machined or sintered. 
     The space of the magnetic armature within the bearing sleeve is sealed toward the bottom by pressing in flux-conducting components. Due to the fact that a deliberate magnetic saturation is generated on an intermediate segment situated on the outer diameter of the bearing sleeve, the two flux-conducting segments, the pole core and the yoke, of the soft iron circuit are separated from each other. 
     Exemplary embodiments of the present invention and their advantages are explained in greater detail below on the basis of the attached figures. The proportions in the figures do not always correspond to the real proportions, since some shapes in the illustration have been simplified and other shapes have been enlarged in relation to other elements for the purpose of better clarification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a sectional representation of an electromagnetic switching device according to the prior art; 
         FIG. 2 a    shows a sectional representation of a first specific embodiment of the electromagnetic switching device, in which the electromagnet casing, the bearing sleeve and the pole core are formed as a one-piece component; 
         FIG. 2 b    shows a sectional representation of the one-piece component according to the first specific embodiment; 
         FIG. 2 c    shows a three-dimensional sectional representation of the one-piece component according to the first specific embodiment; 
         FIG. 3 a    shows a sectional representation of a second specific embodiment of the electromagnetic switching device, in which the electromagnet casing, the bearing sleeve, the pole core and the yoke are formed as a one-piece component; 
         FIG. 3 b    shows a sectional representation of the one-piece component according to the second specific embodiment; 
         FIG. 3 c    shows a three-dimensional sectional representation of the one-piece component according to the second specific embodiment; 
         FIG. 4 a    shows a sectional representation of a third specific embodiment of the electromagnetic switching device, in which the electromagnet casing and the bearing sleeve are formed as a one-piece component, and the pole core and the yoke are separate components; 
         FIG. 4 b    shows a sectional representation of the one-piece component according to the third specific embodiment; and 
         FIG. 4 c    shows a sectional representation and a three-dimensional representation of the pole core, which is mounted as a separate component on the bearing sleeve. 
     
    
    
     DETAILED DESCRIPTION 
     Identical reference numerals are used for the same elements or elements having the same function. Furthermore, for the sake of clarity, only reference numerals which are necessary for describing the particular figure are shown in the individual figures. The illustrated specific embodiments only represent examples of how the electromagnetic switching device according to the present invention may be designed and do not represent a final limitation of the present invention. 
       FIG. 1  shows an electromagnetic switching device  10  according to the prior art. Bearing sleeve  11 , which accommodates magnetic armature  13 , is connected to cup-shaped housing part  50  with the aid of a welding method and is thus part of electromagnetic switching device  10 . Coil  14 , coil carrier  15  and yoke  16  are situated outside bearing sleeve  11 . Bearing sleeve  11 , cup-shaped housing part  50 , coil  14 , coil carrier  15  and yoke  16  are inserted into an injection mold, and extrusion-coated with a plastic compound  52 , so that they are fixed in place in electromagnetic switching device  10 . Cup-shaped housing part  50  is closed with the aid of a conical guiding element  51 , in which a pressure pin  19  is guided. Pressure pin  19  is movable axially along an axis A. 
       FIG. 2 a    shows an electromagnetic switching device  10  according to the present invention according to a first specific embodiment. One-piece component  100 , which is made from a material with the aid of a forming process, is shown in  FIGS. 2 b  and 2 c   . This component includes electromagnet casing  12 , bearing sleeve  11  and pole core  17 . Pole core  17  is formed on outer diameter  22  of bearing sleeve  11 . Coil  14 , coil carrier  15 , yoke  16  and an intermediate segment  18 , which separates pole core  17  and yoke  16  from each other, are inserted between bearing sleeve  11  and electromagnet casing  12 . Bearing  21  in which pressure pin  19  is movably guided along axis A, and movably supported magnetic armature  13 , which is closed by pressing in flux-conducting components  40 , are inserted into inside  24  of bearing sleeve  11 . Bearing sleeve  11  is closed on one side by a cover  23 , which is also formed by the forming process. 
       FIG. 3 a    shows an electromagnetic switching device  10  according to the present invention according to a second specific embodiment. One-piece component  100 , which is made from a material with the aid of a forming process, is shown in  FIGS. 3 b  and 3 c   . In this specific embodiment, the component includes electromagnet casing  12 , bearing sleeve  11 , pole core  17  and yoke  16 . Pole core  17  and yoke  16  are formed on outer diameter  22  of bearing sleeve  11 . Since yoke  16  in this specific embodiment is formed directly on outer diameter  22  of bearing sleeve  11 , one-piece component  100  is closed at the upper end by a yoke plate  31 . A bearing, advantageously a friction bearing  30 , may also be provided in bearing sleeve  11 , which is used to support or guide magnetic armature  13 . All other components which are also present in electromagnetic switching device  10  are positioned in the same way as in the preceding specific embodiment. 
       FIG. 4 a    shows an electromagnetic switching device  10  according to the present invention according to a third specific embodiment. One-piece component  100 , which is made from a material with the aid of a forming process, is shown in  FIG. 4 b   . In this specific embodiment, the component includes electromagnet casing  12  and bearing sleeve  11 .  FIG. 4 c    shows pole core  17 , which in this specific embodiment is mounted as a separate component on outer diameter  22  of bearing sleeve  11 . All other components which are also present in electromagnetic switching device  10  are positioned in the same way as in the preceding specific embodiments. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  electromagnetic switching device 
           11  bearing sleeve 
           12  electromagnet casing 
           13  magnetic armature 
           14  coil 
           15  coil carrier 
           16  yoke 
           17  pole core 
           18  intermediate segment 
           19  pressure pin 
           21  bearing 
           22  outer diameter 
           23  cover 
           24  inside of the bearing sleeve 
           30  friction bearing 
           31  yoke plate 
           40  flux-conducting component 
           50  cup-shaped housing part 
           51  conical guiding element 
           52  plastic compound 
           100  one-piece component 
         A axis