Patent Publication Number: US-6986677-B2

Title: Seal carrying electrical contact

Description:
FIELD OF THE INVENTION 
   The invention relates to an electrical contact and, more particularly, to a contact for an electrical connector having at least one seal member that forms a seal between a contact receiving passageway of the electrical connector and the contact such that liquid is prevented from passing through the contact receiving passageway of the electrical connector. 
   BACKGROUND OF THE INVENTION 
   One field of use of such a contact and electrical connector is to electrically connect electrical conductors on an outer side of a cylinder head wall of a combustion engine with electrical conductors on an inner side of the cylinder head wall of the combustion engine. Examples of such a use include terminating electrical components on the inner side of the cylinder head wall for engine brake management or terminating electromagnetic fuel valves for fuel injection management. In this environment, the contacts and the electrical connectors are exposed to vibrations, high temperatures, and external forces, particularly on the outer side of the cylinder head wall. Additionally, adequate sealing is needed to prevent pressurised engine oil on the inner side of the cylinder head wall from passing through to the outer side of the cylinder head wall and for preventing water on the outer side of the cylinder head wall from passing through to the inner side of the cylinder head wall. 
   An example of such a conventional electrical connector is disclosed in DE-A-196 30 333. The electrical connector has a housing with a plurality of contact receiving passageways that receive contacts. Each of the contacts has a body portion including a conductor engaging end for forming an electrical connection with a corresponding conductor and a terminal end for engaging a mating contact of a mating connector. First and second recesses are formed along each of the body portions for receiving first and second seal members. The first and second seal members are, for example, O-rings, and form a seal between the contact and the contact receiving passageway for preventing liquid from passing through the contact receiving passageway. 
   To use the conventional electrical connector as a lead-through through a cylinder head wall of a combustion engine, the housing of the electrical connector is mounted in a passageway of the cylinder head wall such that the mating connector is on the inner side of the cylinder head wall. In view of the limited space available at the cylinder head wall, the number of contacts that the electrical connector can accommodate is correspondingly limited. For example, if the housing is mounted in a passageway having a diameter of 30 millimeters (mm), then the electrical connector can only accommodate eight contacts. As the number of parameters handled by the motor management of combustion engines and the number of electrical sensors and/or actuators located on the inner side of the cylinder head wall increases, however, it is desirable to also increase the number of contacts that can be accommodated in the housing fitting in the 30 mm passageway. 
   Additionally, the location of the plug connection of the two mating connectors is at the cylinder head wall. Because the cylinder head wall is exposed to particularly strong vibrations, the plug connections are affected by the vibrations, particularly, the contacts having smaller dimensions. Moreover, vibrations and forces exerted on the conductors may cause the contacts to tilt as a result of the resilience of the first and second seal members. If the contacts tilt, the first and second seal members may become deformed. If the first and second seal members become deformed, the seal between the contact and the contact receiving passageway may deteriorate. Because the risk of such deterioration increases with a decrease in the dimensions of the first and second seal members, the ability to reduce the dimensions of the contacts is further limited. 
   It is therefore desirable to provide an electrical connector that can house more than eight contacts in a passageway having a diameter of 30 mm without adversely affecting the performance of the electrical connector. 
   SUMMARY OF THE INVENTION 
   The invention relates to an electrical connector comprising an insulative housing having a plurality of contact receiving passageways extending from a first axial face to a second axial face of the housing. A contact is arranged in the contact receiving passageway. The contact has a substantially cylindrical contact body and a first conductor engaging portion arranged at the first axial face and a second conductor engaging portion arranged at the second axial face. A first seal member is mounted on the contact body. The first seal member has a first plurality of axially spaced annular projections extending away from the contact body that engage an inner surface of the contact receiving passageway. The first plurality of axially spaced annular projections is capable of being bent towards the first axial face. 
   The invention further relates to a contact comprising a substantially cylindrical contact body having a first conductor engaging portion at a first conductor receiving end and a second conductor engaging portion at a second conductor receiving end. A first seal member is mounted on the contact body. The first seal member has a first plurality of axially spaced annular projections extending away from the contact body. The first plurality of axially spaced annular projections has outer ends bendable towards the first conductor receiving end when the contact is inserted into a contact receiving passageway of the electrical connector. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of an electrical connector according to the invention; 
       FIG. 2  is a cross-sectional view of the electrical connector of  FIG. 1  showing contacts arranged therein; 
       FIG. 3  is a top schematic view of the electrical connector of  FIG. 1  taken from a right-hand side of  FIG. 1 ; 
       FIG. 4  is a bottom schematic view of the electrical connector of  FIG. 1  taken from the left-hand side of  FIG. 1 ; 
       FIG. 5  is a schematic view in partial cross-section of an arrangement with the electrical connector of  FIG. 1  showing first and second conductors connected to the contacts of the electrical connector wherein the first and second conductors have terminals at ends remote from the electrical connector; 
       FIG. 6  is a partial cross-sectional view of one of the contacts of  FIG. 5  shown connected to the first and second conductors before being received in a contact receiving passageway of the electrical connector of  FIG. 1 ; and 
       FIG. 7  is a partial cross-sectional view of an alternate embodiment of the contact of  FIG. 6  shown received in the contact receiving passageway of the electrical connector of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows an electrical connector  11 . The electrical connector  11  will be described in greater detail hereafter and will be described by way of example as an electrical lead-through through a cylinder head wall  26  of a combustion engine of a truck. 
   As shown in  FIG. 1 , the electrical connector  11  includes an insulating housing  13  having a first axial face  15  and a second axial face  17 . The housing  13  may be formed, for example, from nylon (PA66) or a reinforced polybutylene terephthalate (PBT). Between the first and second axial faces  15 ,  17  of the housing  13  is a seal receiving recess  21 , which is formed to receive an outer seal member  23 , such as an O-ring, shown in  FIG. 2 . As shown in  FIG. 5 , the outer seal member  23 , for example, seals a housing receiving passageway  25  of a cylinder head wall  26  that has an inner surface  27  and an outer surface  28 . 
   As best shown in  FIG. 2 , the first axial face  15  comprises an axially extending shroud  36 . The shroud  36  forms a cylindrical cavity  91  at the first axial face  15  of the housing  13 . As shown in  FIG. 1 , the second axial face  17  has a flange  29 . The flange  29  radially extends from one peripheral side of the housing  13  and has a flange opening  31  for mounting the flange  29  to the cylinder head wall  26  with, for example, a screw. A grommet  33  having a shape of a half shell axially extends from the second axial face  17  of the housing  13  adjacent to the flange  29 . The grommet  33  has a grommet opening  35 . The second axial face  17  is further provided with an annular recess  105 . 
   As shown in  FIG. 2 , a plurality of contact receiving passageways  18  axially extends through the housing  13 . Each of the contact receiving passageways  18  has a first axial end  19  and a second axial end  20 . The first axial end  19  may be formed to have bevels  109  that taper inward toward the contact receiving passageway  18 , as best shown in  FIG. 6 . 
   A contact  37  is received in each of the contact receiving passageways  18  of the housing  13 . As best shown in  FIG. 6 , each of the contacts  37  has a substantially cylindrical contact body  43 . The contact body  43  may be formed from an alloy, such as phosphorous-bronze (CuSn) or brass (CuZn). The contact body  43  has a main part with an outer diameter  45  smaller than an inner diameter  47  of the respective contact receiving passageway  18 . The contact body  43  has a tubular first conductor engaging portion  49  at a first conductor receiving end  51  and a tubular second conductor engaging portion  53  at a second conductor receiving end  55 . The first conductor engaging portion  49  is in crimp connection with a first stranded conductor  57  that is received in the first conductor engaging portion  49 . The first stranded conductor  57  extends from the first conductor receiving end  51  of the contact body  43 . The second conductor engaging portion  53  is in crimp connection with a second stranded conductor  59  received in the second conductor engaging portion  53 . The second stranded conductor  59  extends from the second conductor receiving end  55  of the contact body  43 . 
   The contact body  43  has a solid middle portion  61  extending between the tubular first and second conductor engaging portions  49 ,  53 . The solid middle portion  61  prevents engine oil, for example, from reaching the second conductor engaging portion  53  by preventing the engine oil from creeping along strands of the first conductor  57  and/or between the strands and an outer insulating coating of the first conductor  57  and/or along the outside of the outer insulating coating. Similarly, water creeping along the strands of the second conductor  59  and/or between the strands and an outer insulating coating of the second conductor  59  and/or along the outside of the outer insulating coating is prevented from reaching the first conductor engaging portion  49 . 
   The contact body  43  has first and second radial collars  63 ,  65 . The first radial collar  63  is located at the first conductor receiving end  51  of the contact body  43  and the second radial collar  65  is located at the inner end of the first conductor engaging portion  49 . Each of the first and second radial collars  63 ,  65  may be formed to have entrance bevels  109 . The outer surfaces of the first and second radial collars  63 ,  65  may be formed to have radial teeth (not shown) that indent into the material of the inner wall of the contact receiving passageway  18 . Alternatively, the outer surfaces of the first and second radial collars  63 ,  65  may be made smooth and adjusted to the inner diameter of the contact receiving passageway  18  either without clearance or with a small clearance of a few millimeters, for example 1/10 mm, so that the first and second radial collars  63 ,  65  may be press-fit in the contact receiving passageway  18 . The first and second radial collars  63 ,  65  fix the contact  37  within the contact receiving passageway  18 , for example, by press-fitting, and prevent the contact body  43  from tilting within the passageway  18 . 
   First and second seal members  67 ,  69  are mounted on the contact body  43  at an axial distance from each other by, for example, press-fit mounting, molding, or vulcanizing first and second seal members  67 ,  69  onto the contact body  43 . The first and second seal members  67 ,  69  are made of a heat-resistant, stress-resistant, and contaminant-resistant resilient material that retains permanent elasticity even in harsh environments. For example, suitable materials for the first and second single seal members  67 ,  69  may be a silicone elastomer (VMQ) or a fluor-silicone elastomer (FVMQ). 
   The first seal member  67  is mounted on the contact body  43  adjacent to the solid middle portion  61 . The first seal member  67  has a first axial side  71  facing the first conductor receiving end  51  of the contact body  43  and a second axial side  73  facing the second conductor receiving end  55  of the contact body  43 . The first seal member  67  includes a first plurality of axially spaced annular projections  79 . The first plurality of projections  79  axially extend such that when the contact  37  is pushed into the contact receiving passageway  18  from the first axial end  19  thereof, outer ends of the first plurality of projections  79  are bent towards the first conductor receiving end  51  of the contact body  43 . 
   The second seal member  69  is mounted on the contact body  43  adjacent to the second conductor receiving end  55  and has a portion that axially extends beyond the second conductor receiving end  55  of the contact body  43 . The second seal member  69  has a first axial side  75  facing the first conductor receiving end  51  of the contact body  43  and a second axial side  77  facing the second conductor receiving end  55  of the contact body  43 . The second seal member  69  has a second plurality of axially spaced annular projections  81 . The second plurality of projections  81  axially extend such that when the contact  37  is pushed into the contact receiving passageway  18  from the first axial end  19  thereof, outer ends of the second plurality of projections  81  substantially contact the inner wall of the contact receiving passageway  18  but either remain straight or are bent less than the first plurality of projections  79 . 
   Although the first and second seal members  67 ,  69  are illustrated as each having three of each of the first and second annular projections  79 ,  81 , the number of projections is not limited to three and may vary depending on the desired sealing effect for a particular application. 
     FIG. 7  shows an alternate embodiment of the contact  37 . In the alternate embodiment, the contact  37  has a single seal member  83  made of the same material as the first and second seal members  67 ,  69 . The single seal member  81  has the first and second pluralities of annular projections  79 ,  81 . The first plurality of projections  79  is arranged to face the first conductor receiving end  51 , and the second plurality of projections  81  is arranged to face the second conductor receiving end  55 . The axial part of the single sealing member  83  having the second plurality of projections  81  extends beyond the second conductor receiving end  55  of the contact body  43 . When the contact  37  is pushed into the contact receiving passageway  18  from the first axial end  19  thereof, the outer ends of the first plurality of projections  79  are bent towards the first conductor receiving end  51  of the contact body  43  and the outer ends of the second plurality of projections  81  substantially contact the inner wall of the contact receiving passageway  18  without being bent or by being bent less than the first plurality of projections  79 . By bending the outer ends of the first plurality of projections  79  towards the first axial end  19  of the passageway  18 , the seal between the passageway  18  and the first plurality of projections is increased when engine oil pressing against the first plurality of projections  79  urges the bent outer ends of the first plurality of projections  79  against the inner wall of the passageway  18 . 
   The axial region of the second plurality of projections  81  of the single seal member  83  is provided with a plurality of small projections  85  extending inwardly from an inner diameter of the single sealing member  83 . The small projections  85  contact an outer periphery of the second conductor  59  to prevent, for example, water from passing from the second axial side  17  between the second conductor  59  and the inner periphery of the single sealing member  83 . Water, therefore, is blocked from passing by either the inner periphery or the outer periphery of the sealing member  83 . 
   Although the single seal member  83  is illustrated as having three first annular projections  79  and two second and small annular projections  81 ,  85  the number of projections is not limited to these amounts and may vary depending on the desired sealing effect for a particular application. 
   The contact body  43  has a plurality of radially extending annular metal ribs  87  in a region where the single seal member  83  is seated. The inner periphery of the single seal member  83  has a plurality of complementarily formed radially extending annular recesses  89  for receiving the ribs  87 . The ribs  87  and the recesses  89  thereby secure the single seal member  83  to the contact body  43 . The single seal member  83  may be placed on the contact body  43  by pressing it over the contact body  43  with a tool or by molding or vulcanizing the single seal member  81  onto the contact body  43 . 
   Although the single seal member  83  is only shown having the small projections  85 , the inner periphery of the second sealing member  69  of the embodiment of  FIG. 6  may also be formed with small projections  85  depending on the desired application. Additionally, the first seal member  67  and/or the second seal member  69  and the contact body  43  of the embodiment of  FIG. 6  may be formed with the ribs  87  and recesses  89 , respectively, depending on the desired application. 
   An arrangement showing the electrical connector  11  positioned in the cylinder head wall  26  of an engine will now be explained in greater detail with reference to  FIG. 5 . As shown in  FIG. 5 , a first plurality of the first conductors  57  extending from the first axial face  15  of the housing  13  are each arranged as twisted-pairs. Each of the twisted-pairs is terminated by a 2-position connector  93 . A second plurality of the first conductors  57  is arranged as straight pairs. Each of the two conductors of each of the straight pairs is terminated by a 1-position connector  95 . In one application of the invention, the 2-position connectors  93  make a plug connection to electromagnetic fuel injection valves (not shown), and the 1-position connectors  95  make a releasable connection to engine brake management components (not shown). The first conductors  57  are arranged as flying leads and are heat-protected by means of heat-resistant tubing  97 , which secures the cables and protects the cable insulation against wear. 
   The second conductors  59  extending from the second axial face  17  of the housing  13  are bent by 90 degrees and are bundled by the grommet opening  35 . The grommet  33  thereby prevents the cable having the second conductors  59  from axially twisting and further prevents insulation rubbing. The second conductors  59  extend through a bellow  99  to a 12-position connector  101 . The free end of the bellow  99  is adapted to be mounted on a collar  103 , which is pre-mounted on the connector  101 . The connector  101  has, for example, twelve contacts  102 , by means of which the second conductors  59  may be connected to a motor management system (not shown). A tube (not shown) extends between the second axial face  17  of the housing  13  and the grommet  33 . The tube (not shown) has a 90 degree bend and accommodates parts of the second conductors  59  extending between the second axial face  17  of the housing  13  and the grommet  33 . The tube (not shown) is snapped into and secured by the annular recess  105  of the housing  13 . 
   To mount the arrangement of  FIG. 5 , the first conductor  57  is inserted into the tubular first conductor engaging portions  49  and is crimped therein. The contacts of the connectors  93 ,  95  are crimped on the free ends of the first conductors  57 . The first seal member  67  is mounted on the contact body  43 . The second conductor  59  is inserted into the tubular second conductor engaging portions  53  and crimped therein. The second seal member  39  is mounted on the contact body  43 . The second conductor  59  with the second seal member  69  mounted thereon and the contact  37  connected to the second conductors  59  is then slid into the respective contact receiving passageway  18  of the housing  13  (twisted pair by twisted pair in the case of the embodiment shown in  FIG. 5  where each of the connectors  93 ,  95  terminates two of the first conductors  57 ). The bevels  109  formed on the housing  13  and the entrance bevels  107  formed on each of the collars  63 ,  65  facilitate entry of the contact  37  into the respective contact receiving passageway  18 . The second conductor  59  is then fed through the grommet opening  35  and the contacts  102  are crimped to the free end of the second conductor  59 . The contacts  102  are led through the bellows  99  and are inserted into the housing of the connector  101  with the pre-mounted collar  103 . The resulting harness is now mounted on the cylinder head wall  26  by inserting the housing  13  of the harness into the housing receiving passageway  25  of the cylinder head wall  26 . Because the first and second conductors  57 ,  59  are directly connected to the contact  37 , there is no plug connection in the region of the cylinder head wall  26 . Thus, a stable connection is provided that has a high resistance to vibrations and mechanical forces applied to the first and second conductors  57 ,  59 . 
   When using the contact  37  as a lead-through through the cylinder head wall  26 , the contact receiving passageways  18  could also be formed in the cylinder head wall  26  itself. This arrangement is possible if the cylinder head wall  26  is made of an electrically insulating material, such as, ceramic or plastic, or if the cylinder head wall  26  is made of an electrically conducting material, such as, steel, and the inner wall of each of the contact receiving passageways  18  is coated with an electrically insulating material. This arrangement allows a rather large number of contacts  37  to be arranged in a limited space. This arrangement, however, can not be used when both ends of the harness comprising the contact  37  already have connectors  93 ,  95  attached thereto that can not be passed through the contact receiving passageway  18  formed in the cylinder head wall  26 . 
   In an embodiment wherein the contacts  37  are pushed into contact receiving passageways directly formed in the cylinder head wall  26  as well in the embodiment wherein the contacts  37  are received in passageways  18  of the housing  13 , the cylinder head wall  26  is removed from the cylinder head while the contacts  37  crimped to the respective first conductors  57  are pushed into the respective contact receiving passageway of either the cylinder head wall  26  or the housing  13 , which is already fixed in the housing receiving passageway  25  of the cylinder head wall  26 . 
   The first axial ends  51  of the contact body  43  may additionally be fixed by potting  82  instead of or in addition to press-fitting the collars  63 ,  65  into the contact receiving holes  18 . Fixing the contact  37  with the potting  82  is advantageous in that the contact  37  and the cable comprising the first conductors  57  are fixed and movements thereof are damped. The potting  82  additionally protects against high temperature and blocks oil from entering into the cable and flowing back to the connectors  93 ,  95 .