Patent Publication Number: US-2018033574-A1

Title: Arrangement for an Electrical Switch Element With a Seal

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/943,592 filed Nov. 17, 2015 which claims priority under 35 U.S.C. §119 to PCT/EP2014/061011 filed May 28, 2014, claiming priority to German Patent No. 102013210194.5 filed May 31, 2013. 
    
    
     FIELD OF THE INVENTION 
     The invention concerns an electrical switch element, and more particularly, an electrical switch element with a switch chamber. 
     BACKGROUND 
     Electrical switch elements such as relays or contactors are standard components that have long been used in electrical engineering. When the contacts are opened, in particular at high current strength, arcs frequently form between the contacts. Arc formation is problematic on the one hand because the arcs are conduits, such that, as long as an arc is present, the electrical switch is not interrupted, and, on the other, because the hot plasma of the arc may damage the components of the electrical switch element both inside and outside of the switch chamber. This results in a reduced useful life of the switch elements. 
     SUMMARY 
     The object of the invention is to provide an arrangement for an electrical switch element that facilitates the elimination of any arcs and increases the useful life of the switch without increasing manufacture costs. The disclosed electrical switch element has a switch chamber having contacts and an opening, a propulsion element extending through the opening in the switch chamber and having an annular flange, and a seal having an annular protrusion surrounding the opening. The propulsion element is movable within the opening to open or close the contacts, and in an end position of the propulsion element, the annular flange abuts the annular protrusion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying figures, of which: 
         FIG. 1  is a cross-section of part of an electrical switch element according to a first embodiment of the invention; 
         FIG. 2  is a cross-section of a seal according to the first embodiment; 
         FIG. 3  is cross-section of a seal according to a second embodiment of the invention; 
         FIG. 4  is a cross-section of a seal according to a third embodiment of the invention; 
         FIG. 5  is a cross-section of a seal according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     The invention is explained in greater detail below with reference to embodiments of an electrical switch element. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and still fully convey the scope of the invention to those skilled in the art. 
       FIG. 1  shows an embodiment of an arrangement of an electrical switch element  1  according to the invention in cross-section. The arrangement for an electrical switch element  1  comprises a switch chamber  3 . The switch chamber  3  contains contacts  5 . The contact arrangement  7  shown, which is configured in the form of a contact bridge to connect two contacts  5 , is meant merely as an example of contacts  5  capable of opening and/or closing. 
     The switch chamber  3  has a wall  9 , which has an opening  11 . A propulsion element  13  protrudes through the opening  11  into the switch chamber  3 . The propulsion element  13  is functionally coupled with the contacts  5 . In  FIG. 1 , the propulsion element  13  is in its end position E. The propulsion element  13  is surrounded by the seal  15 . In the end position E of the propulsion element  13 , the opening  11  is sealed by the seal  15 . The inside  17  of the switch chamber  3  is separated from the area  19  outside the switch chamber in the end position E. 
     The seal  15  includes a stationary part  21  of the wall  9  and an annular flange  25  of the propulsion element  13 . 
     The stationary part  21  extends annularly around the opening  11 , and is formed as an annular protrusion  23 . The stationary part  21  is part of the wall section  24 , which also contains the opening  11 . The protrusion  23  is formed so as to thicken the wall  9  in this exemplary embodiment. However, the protrusion  23  may also be formed by an additional element that abuts the wall  9 . The protrusion  23  protrudes into the switch chamber  3 . 
     The annular flange  25  on the propulsion element  13  protrudes in parallel to a plane  27  of the opening  11 . The annular flange  25  may be integrally formed with the propulsion element 
     The structure and function of the seal  15  are further described in  FIG. 2 .  FIG. 2  shows an enlargement of the seal  15  according to the invention from  FIG. 1  in cross-section. 
     The annular flange  25  abuts the annular protrusion  23  in the end position E, and completely overlaps with the opening  11 . This completely seals the switch chamber  3 . The side of the flange  25  facing the stationary part  21  forms a sealing surface  33 ; the side of the protrusion  23  facing the flange  25  forms the sealing surface  33 ′. In the end position E, the sealing surfaces  33  and  33 ′ abut each other, thus sealing the switch chamber  3 . Further, in the end position E, the section  24  having the opening  11  is positioned apart from the switch chamber  3  by a distance  31 . This distance  31  roughly corresponds to the thickness  29  of the flange  25 . 
     A support element  35  of the switch element  1  may abut an outer side  37  of the section  24  on the switch chamber  3 . 
     The functioning of the seal  15  will now be described. The propulsion element  13  begins in a switching position (not shown), in which the contacts  5  are closed. If the contacts are opened and an arc (not shown) forms within the switch chamber  3 , the gas heated by the arc inside the switch chamber  3  seeks to leave the switch chamber  3  via the opening  11 . The pressure of the gas forces the propulsion element  13  along the opening direction O into the end position E; the annular protrusion  23  may serve as a stop for the flange  25 , thus defining the end position E of the propulsion element  13 . The end position E is reached by the propulsion element  13  when the opening of the contacts  5  is complete. 
     In order to reduce the stress on the material of the wall section  24  when the flange  25  collides with the protrusion  23 , the support element  35  abutting an outer side  37  of the section  24  may absorb part of the kinetic energy of the propulsion element  13 . 
     The switch element  1  may have a damping configuration  39 . In a particularly simply produced embodiment, the protrusion  23  is part of the damping configuration  39 . To this end, the protrusion  23  may be made of a soft or elastic material, or the wall section  24  may be made of an elastic material. The wall section  24  and the annular protrusion  23  may be produced by means of multi-component injection moulding, whereby the annular protrusion  23  may be made of a more elastic material than the rest of the wall section  24 . 
     In a variation (not shown), the flange  25  may directly abut a spring element  41  of the switch element  1 . The side of the flange  25  facing away from the wall  9  may be configured such that the spring element  41  may be directly supported by it. In particular, the annular flange  25  may have a greater diameter than the spring element  41 . 
       FIG. 3  shows another embodiment of a seal of an electrical switch element  1  according to the invention. 
     The support element  35  adjacent to the switch chamber  3  is positioned apart from the switch chamber  3 , such that a movement space  43  is formed between the wall section  24  and the adjacent support element  35 . The movement space  43  runs annularly around the propulsion element  13 . The switch chamber  3  of the wall  9  has an elastically deviating wall section  45 . The wall section  45  may be part of the wall section  24  having the opening  11 , or be identical to it. The elastically deflectable wall section  45  may deviate elastically into the movement space  43 . The wall section  45  thus serves to absorb the movement of the propulsion element  13  in its resting position. The movement space  43  and the wall section  45  are part of the seal  39 . The wall section  45  may have an annular area  49  with a greater wall thickness than the rest of the wall  9  in order to increase its elasticity. 
     The adjacent support element  35  delimits the movement space  43  in a direction away from the switch chamber  3 . The adjacent support element  35  may be made, e.g., of part of a propulsion system (not shown). The adjacent support element  35  may, e.g., be part of a coil core surrounding the propulsion element  13 . The wall  9  may have a receiving groove  47 , which may run annularly around the opening, on the side facing the adjacent support element  35 . The groove  47  may serve to fasten and align an adjacent support element  35 . The groove  47  may form the annular space  49  with a reduced wall thickness compared to the rest of the wall  9 . 
       FIG. 4  shows part of another embodiment of an electrical switch element  1  according to the invention.  FIG. 4  shows the propulsion element  13  outside of its end position E. 
     The movement space  43  contains an annular secondary seal  51 . The secondary seal  51  is penetrated by the propulsion element  13 . An internal diameter  53  of the secondary seal  51  is smaller than an internal diameter  55  of the opening  11 . The secondary seal  51  may be configured such that it tightly surrounds the propulsion element  13 . 
     The secondary seal  51  may have a thickness  57  smaller than a width  59  of the movement space in a direction parallel to the opening direction O of the propulsion element  13 . The secondary seal  51  is not connected with the propulsion element  13  in a fixed manner, and can move parallel to the opening direction O within the movement space  43 . The secondary seal  51  is both part of the seal  15  and of the damping configuration  39 . 
     The functioning of the secondary seal  51  is described below: If the propulsion element  13  is in a switching position (not shown), the position of the secondary seal  51  is undefined within the movement space  43 . If the contacts are opened and an arc (not shown) forms within the switch chamber  3 , the gas heated by the arc inside the switch chamber  3  seeks to leave the switch chamber  3  via the opening  11 . The movement of the gas through the opening  11  can press the secondary seal  51  onto the inner side  60  of the movement space opposite the opening  11 . The secondary seal  51  then abuts the inner side  60 . Because the secondary seal  51  surrounds the propulsion element  13 , the movement space  43 , and thus the inside  17  of the switch chamber  3  as well, is closed off from the area  19  outside of the switch chamber  3 . 
     The secondary seal  51  already seals the switch chamber  3  before the propulsion element  13  reaches its end position E. If the propulsion element  13  moves quickly in the opening direction O, the flange  25  will collide with the stationary part  21 . This moves the elastically delfectable wall section  45  into the movement space  43 , and may hit the secondary seal element  51 . The secondary seal  51  may be made of an elastic material and effectively absorb the movement of the wall section  45 . If the propulsion element  13  has reached its end position E (not shown), in addition to the seal provided by the secondary seal  51 , which abuts the inner side  60 , the switch chamber  3  is additionally closed and sealed due to the fact that the annular flange  25  abuts the stationary part  21 . 
       FIG. 5  shows part of another embodiment of a switch element  1  according to the invention. The secondary seal  51  is formed as a press-fit element  61 . 
     The thickness  63  of the press-fit element  61  corresponds at least to the width  59  of the movement space  43 . If the thickness  63  of the press-fit element  61  is greater than the width  59  of the space  43 , the press-fit element  61  is press-fit into the space  43  by the pressure exerted by the wall section  45 , and abuts both the outer side  37  of the wall section  24  and the inner side  60  opposite the opening  11 . 
     Because the press-fit element  61  tightly surrounds the propulsion element  13 , it is a permanent seal that seals the switch chamber  3  off from the area  19  outside of the switch chamber  3  in every position of the propulsion element  13 . The press-fit element  61  is thus part of the seal  15 . If the press-fit element  61  itself is made of elastically deformable material, it additionally serves as part of the damping configuration  39 , as it effectively absorbs movement of the elastically deviating wall section  45  into the space  43 . The wall section  45  directly abuts the press-fit element  61 . 
     Because the press-fit element  61  is held by force in the space  43 , it can form an additional guide for the propulsion element  13 . This can improve the reliability of the electrical switch element  1 . The press-fit element  61  may be equipped, e.g., by means of its dimensions or material properties, such that it can only be moved perpendicularly to the opening direction  0  with increased force. In particular, it may be configured such that, at the first operation of an assembled electrical switch element  1 , imprecisions in production and/or assembly are compensated by the fact that, when the propulsion element  13  moves, the press-fit element  61  initially moves a certain distance in the movement space perpendicularly to the opening direction O, until the propulsion element  13  is arranged in a position that may be specified by additional elements of the electrical switch element. The movability of the press-fit element  61  perpendicularly to the opening direction O thus ensures that the propulsion element can move without tension in and opposite the opening direction O during the further operation of the electrical switch element  1 . 
     The solution of the invention has the advantage that the seal effectively seals the switch chamber opening after the contacts have been separated. This keeps any plasma generated by an arc in the switch chamber inside the switch chamber. This prevents damage to the components of the electrical switch element outside the switch chamber. Because the plasma and the hot gas surrounding the plasma are limited to the volume of the switch chamber, the increased pressure that builds up in the switch chamber shortly after the formation of an arc also effectively facilitates the elimination of the arc. This interrupts the current flow and reduces any adverse effect on the components inside the switch chamber.