Abstract:
The present invention refers to a cover ( 17 ) of a contactor ( 1 ) of a starter for motor vehicle, comprising—a plastic portion ( 18 ) delimiting a contact chamber ( 15 ) volume,—two plugs ( 43, 45 ) in an electrical conductor material which cross the plastic portion, each of the two plugs ( 43, 45 ) having an end in the contact chamber ( 15 ),—a seal ( 37 ) which is arranged on the plastic portion ( 18 ) to isolate the contact chamber ( 15 ) when the cover ( 17 ) is assembled with a coil casing ( 5 ) of the contactor ( 1 ), the seal ( 37 ) being assembled in a fixed manner to the cover ( 17 ).

Description:
[0001]    The present invention refers to the domain of the starters for motor vehicles and more particularly to the contactor of the starters. 
         [0002]    The contactors of the state of the art comprise a coil arranged in a coil casing and configured for moving axially the mobile part of a magnetic core located in the center of the coil. The magnetic core is acting on a rod which controls a contact plate located outside of the coil casing in a contact chamber. The contact plate is destined for joining two electrical contacts having their ends in the contact chamber when the mobile part of the magnetic core is moved axially by the coil. The contact chamber is delimited by a cover through which the two electrical contacts are arranged. The cover is fastened to the coil casing. Furthermore, in order to ensure the isolation of the contact chamber in particular against humidity, a seal is needed between the cover and the coil casing. In the state of the art, the seal is made using a rubber seal which is positioned during assembly of the cover thanks to coil wires going through the cover. However, with such seal, there is a risk of deformation of the seal during transport (before assembly on the contactor) due to the flexibility of the material so that dedicated packaging needs to be foreseen leading to extra costs. Furthermore, the positioning of the seal is cumbersome and there is a risk of incorrect positioning which may lead to an isolation failure that may induce humidity to enter into the chamber and may cause lack of electrical contact due to the formation of ice on the contacts in low temperature. Ice is formed due to humidity condensation on terminals because of the temperature gradient induced by the accelerated cooling of the terminals with respect to the internal contact chamber temperature. 
       SUMMARY OF THE INVENTION 
       [0003]    It is therefore an object of the present invention to overcome the precited drawbacks of the state of the art and to provide a solution enabling to ease the assembly of the contactor while ensuring a correct isolation. 
         [0004]    Thus, the present invention refers to a cover of a contactor of a starter for motor vehicle, comprising
       a plastic portion delimiting a contact chamber volume,   two plugs in an electrical conductor material which cross the plastic portion, each of the two plugs having an end in the contact chamber,   a seal which is arranged on the plastic portion to isolate the contact chamber when the cover is assembled with a coil casing of the contactor, the seal being assembled in a fixed manner to the cover.       
 
         [0008]    According to another aspect of the present invention, the seal is assembled to the plastic portion by overmolding. 
         [0009]    According to a further aspect of the present invention, the plastic portion and the seal are obtained by a bi-injection process. 
         [0010]    According to another aspect of the present invention, the plastic portion and the seal are assembled together using a self-adhesive tape. 
         [0011]    According to another aspect of the present invention, the plastic portion and the seal are glued together. 
         [0012]    According to an additional aspect of the present invention, the seal and the plastic portion comprise a plurality of pins and a plurality of holes complementary to the pins to ensure the fixation of the seal to the cover. 
         [0013]    According to another aspect of the present invention, the pins have a length comprised in a range from 2 to 5 mm and a diameter comprised in a range from 1 to 3 mm. 
         [0014]    According to a further aspect of the present invention, the seal comprises more than ten pins and wherein the pins are spaced apart of 3 to 10 mm. 
         [0015]    According to an additional aspect of the present invention, the seal has a rectangular shape. 
         [0016]    According to another aspect of the present invention, the seal is made of thermoplastic elastomer. 
         [0017]    According to another aspect of the present invention, the seal is around the chamber in order to add a contact plate after the seal on the cover. 
         [0018]    According to another aspect of the present invention, the seal comprise an opening corresponding to a contact plate of the contactor. 
         [0019]    This allows facilitating the process by mounting the seal on the cover and adding a contact plate with a rod after with a fixed part and the other elements of the contactor. 
         [0020]    The present invention also refers to a contactor comprising a cover as disclosed above. 
         [0021]    According a a aspect of the invention, the contactor comprising a fixed part of the magnetic core, a contact plate which is between the magnetic core and the two plugs, and wherein the seal is around the contact plate. 
         [0022]    The present invention also refers to a starter comprising a contactor as disclosed above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  represents a sectionnal view of a contactor; 
           [0024]      FIG. 2  represents a diagram of a cover and an associated seal according to the present invention; 
           [0025]      FIG. 3  represents a diagram of a cover according to the present invention; 
           [0026]      FIG. 4  represents a diagram of a seal according to the present invention. 
       
    
    
       [0027]    In these drawings, the elements having the same reference correspond to elements having a similar function. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0028]      FIG. 1  represents a diagram of a contactor  1  of a starter comprising a coil  3  located in a coil casing  5 . The center of the coil  3  defines a tubular chamber  6  wherein a magnetic core  7  is arranged. The magnetic core  7  comprises a mobile part  7   a  configured to be displaceable axially from a rest position represented in  FIG. 1  to an active position. In this rest position, the mobile part  7   a  is in contact with a stop  9  under the constraint of a first helicoidal spring  11 . In the active position, the mobile part  7   a  of the magnetic core comes in contact with a fixed part  7   b  of the magnetic core  7  under the action of the coil  3 . When moving to the active position, the mobile part  7   a  of the magnetic core  7  acts on a rod  13 , also called contact axis, which lies from the tubular chamber  6  through the fixed part  7   b  of the magnetic core  7  and protrudes in a contact chamber  15  which is delimited by a cover  17 . The cover  17  is fastened to the coil casing  5  and is crossed by two conductive plugs  43  and  45  having each an end protruding in the contact chamber  15 . The two conductive plugs  23  protrude therefore on one side of the contact chamber  15  whereas the rod  13  protrudes on the opposite side. The rod  13  is linked to a contact plate  19  located in the contact chamber  15 , the rod  13  and the contact plate  19  forming a contact element  21 . The contact plate  19  is arranged to come into contact with both plugs  23  and  25  when the contact element  21  is moved by the displacement of the moving part  7   a  of the magnetic core  7  in the active position. The contact element  21  is therefore configured to be displaceable between a first position wherein the contact plate  19  is in contact with the fixed part  7   b  of the magnetic core  7  and a second position wherein the contact plate  19  comes into contact with both plugs  23  and  25 . A second helicoidal spring  27  is disposed between the cover  17  and the contact element  21  to force the contact element  21  in the first position when the moving part  7   a  of the magnetic core  7  is in its rest position. 
         [0029]    The cover  17  will now be described in more details based on  FIG. 2 . 
         [0030]    The cover  17  comprises a circular face that comes into contact with the fixed part  7   b  of the magnetic core  7  and with the coil casing  5  surrounding the magnetic core  7 . The cover  17  is fastened to the coil casing  5  or to the fixed part  7   b  of the magnetic core  7  for example thanks to coil ends (not represented in  FIG. 2 ) arranged through the holes  29  and  31 . The cover  17  may comprise a positioning coding such as a pair of pins  33  and  35  in the present case in order to ensure the right positioning of the cover  17  on the coil casing  5  or the fixed part of the magnetic core  7 . The cover comprises two plugs  43  and  45  (represented in  FIG. 3 ) made of an electrical conductor material, for example copper, that protrude in the contact chamber  15  through dedicated holes  47  and  49 . 
         [0031]    Furthermore, a seal  37  is placed between the cover  17  and the fixed part  7   b  of the magnetic core  7  to ensure a hermetic closing of the contact chamber  15  to prevent the introduction of impurities and/or humidity within the contact chamber  15 . The seal  37  is arranged in a fixed manner to the cover  17 . The fixation is ensured for example by a plurality of pins  39  and complementary holes  41  as represented in  FIGS. 3 and 4 . The pins  39  can be arranged on the seal  37  and the holes  41  arranged on the cover  17  as represented in  FIGS. 3 and 4  or the pins can also be arranged on the cover  17  so that the holes are then located on the seal  37 . 
         [0032]    In an alternative embodiment, the pins  39  can be distributed between the seal  37  and the cover  17 . The number and the size of the pins  39  may vary depending on the required fixation force between the seal  37  and the cover  17 . In the present case, the pins  39  have a length comprised in a range from 3 to 5 mm and a diameter comprised in a range from 1 to 3 mm. The space between two pins  39  may also vary depending on the fixation required. In the present case, the spacing is regular and is comprised in a range from 5 to 10 mm. The seal  37  has a rectangular shape but other shapes may also be chosen depending on the shape of the contact chamber  15 . The structure  18  of the cover  17  is made of a plastic having a high stiffness, such as a thermoplastic material, for example a polyamide (PA46 or PA66) filled with fiber glass in different ratios or thermoset materials such as phenolic resins filled with fiber glass in different ratios, in order to apply the required pressure on the seal  37  to ensure the hermetic closing of the contact chamber  15  whatever the constraints imposed by the movement of the different elements of the contactor  1  and notably the contact element  21 . Alternatively or in combination with the pins, self-adhesive tape or glue can be used for assembly of the seal to the cover. 
         [0033]    The seal  37  is made of a plastic, for example a thermoplastic elastomer or a rubber which can be injected such as TPE du type EPDM-PP like the Santoprene™ which is softer than the plastic used for the plastic portion  18  of the cover  17  and that can be compressed between the cover  17  and the fixed part  7   b  of the magnetic core  7  or the coil casing  5  to ensure the hermetic closing of the contact chamber  15 . Furthermore, the plastic of the seal  37  needs to be adapted to be injected or overmolded. 
         [0034]    According to a first embodiment, the seal  37  is overmolded directly on the cover  17 . 
         [0035]    According to a second embodiment, the plastic portion  18  of the cover  17  and the seal  37  are obtained by bi-injection. 
         [0036]    With these processes, the manufacturing of the seal  37  is easy. Furthermore, there is no problem of placement or deformation of the seal  37  before assembly as the seal  37  is already placed in fixed manner on the cover  17  during manufacturing. The risk of leaks due to a noncompliant seal  37  is therefore greatly reduced.