Patent Publication Number: US-6702601-B2

Title: Circular electrical connector

Description:
BACKGROUND OF THE INVENTION 
     This invention refers to electrical connectors of circular type and, more in particular, is directed to a female electrical connector for low and/or high voltage connecting devices, mainly used for the connection of solenoid valves, pumps, motors, sensors and the like, capable of working under mechanically and electrically stressed conditions. 
     Both the female and the male connectors can be either of the square or rectilinear type, since each of them is provided with two or more male and female type of electrical contact members, which can be axially coupled together. 
     STATE OF THE ART 
     Electrical connectors of the aforementioned kind are widely in use in several fields, and generally comprise a casing made of rubber or other suitable plastic material, over moulded to a contact-supporting body of nylon or any other substantially rigid type of electrically insulating material, in which the seats for housing the electrical contacts are obtained. 
     A sliding and freely rotating bush of one of the two connectors, externally surrounding the contact-support body, screws onto a ring nut of the other connector, to maintain them in an appropriately coupled condition. 
     Circular electrical connectors of conventional-type present a number of drawbacks, the main one primarily consists in an insufficient contact pressure between the male and female electrical contacts of the two connectors, which in turn is liable to cause serious difficulties for the electrical equipments to which they are connected, especially at low input current and/or voltage values. 
     In conventional type connectors it is consequently extremely difficult to guarantee the certainty of the electrical contact, due to the fact that, in order to allow the introduction of the male contact elements, the female contact elements must be able to widen out inside their housing; for this reason the housing must be shaped in such as way as not to create any interference with the radially expansible part of the female electrical contact, which could therefore easily slip out the support-body during the assembling. 
     There is also the problem of ensuring a satisfactory watertight seal between the two coupled male and female connectors; in this connection, use is normally made of an annular gasket in an appropriate seat, designed to be pressed between facing surfaces of the two connectors. 
     Even though the use of annular gaskets affords a satisfactory seal, in practice it is difficult to guarantee a uniform sealing pressure around the entire circumference of the connectors, with the consequent risk of moisture or water infiltration at the points where the gasket becomes deformed or is compressed to a lesser degree. 
     SCOPES OF THE INVENTION 
     The general scope of this invention is to provide a new and improved electrical connecting device, comprising a male connector and a female connector, which are particularly suitable for remedying the above-mentioned problems. 
     In particular, one scope of this invention is to provide an electrical contact device as referred to above, which is capable of providing a higher contact pressure between the male and female electrical contact members of the two connectors, thereby eliminating any risk of false contacts, and of such kind as to ensure a satisfactory electrical contact between the two connectors. 
     A still further scope of this invention is to provide an electrical connecting device as referred to previously, which is capable of ensuring a more efficient watertight seal, and is provided with means capable of preventing an accidental unscrewing of the two coupling ring nuts, under any condition of use of the connectors. 
     BRIEF DESCRIPTION OF THE INVENTION 
     More in particular, according to the invention an electrical connecting device has been provided comprising: 
     a male connector and a female connector, in which both the connectors comprise 
     a casing and a contact-support body of electrically insulating material; and 
     in which each of the connectors is provided with an axially sliding and threadable locking nut which can be screwed against annular shoulders of the contact-support bodies, wherein: 
     the contact-support body of the female connector is made of elastomeric material; 
     wherein each electrical contact member of the female connector comprises a conical portion elastically yielding in a radial direction, press-fitted into a seating hole of the contact-support body in elastomeric material of the connection device; and 
     wherein the contact-support bodies of the female and male connectors present opposite annularly shaped shoulder surfaces, designed to be sealingly pressed one against the other in the coupled condition of the electrical connecting device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and further features of the electrical connecting device according to this invention, will be more clearly evident from the following description with reference to the accompanying drawings, in which: 
     FIG. 1 shows a partial cutaway view of the two connectors coupled together; 
     FIG. 2 shows an enlarged detail of FIG. 1; 
     FIG. 3 shows an enlarged detail of the contact-supporting body of the female connector, along the line  3 — 3  of FIG. 4; 
     FIG. 4 shows a view along the line  4 — 4  of FIG. 3; 
     FIG. 5 shows a more highly magnified enlarged detail of FIG. 2; 
     FIG. 6 shows a further enlarged detail of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The electrical connecting device shown in FIG. 1, comprises a first male connector  10  for example of the square type, and a second female connector  11  for example of the linear type. 
     The male connector  10  in turn comprises a casing  12  made of rubber or other suitable plastic material, which is over-moulded to a contact-support body  13  made of rigid plastic material, for example made of nylon; the body  13  comprises a plurality of contact pins  14  each designed to fit axially into a corresponding female contact member on the other connector  11 , as explained further on. 
     As can be more clearly seen from the enlarged view of FIG. 2, the male contact-support body  13  is provided with a cylindrical shank  15  for connection with the casing  12 , which contains the seat holes for the insertion of the contact pins  14 . 
     The contact-support body  13  extends into a cylindrical wall  16  provided at its fore end with an annular shoulder  17  having an internal rim  17 ′. 
     A ring nut  18  provided with an external thread  18 ′, axially slides and freely rotates on the cylindrical portion of the casing  12  and of the contact-support body  16 . 
     The female connector  11  in turn comprises a casing  19  made of rubber or other suitable plastic material, over moulded to a contact-support body  20  provided with a plurality of female contact members  21  fitted into appropriate seating holes, to receive the contact pins  14  of the male connector  10 . 
     More precisely, the contact-support body  20  of the female connector is provided with a shank  22  for connection with the casing  19  of the connector; the shank  22  extends forwards into a cylindrical portion  23  designed to penetrate into the cylindrical wall  16  of the contact-support body  13  of the male connector  10 . 
     The contact-support body  20  of the female connector  11  in turn is provided with a ring nut  24  having an internal thread  25  designed to couple with the external thread  18 ′ of the ring nut  18 . 
     At its rear end, the ring nut  24  also comprises an inwardly-folded rim  26 , which is designed to come into contact with an annular shoulder  27  of the contact-support body  20 , between the rear shank  22  and the fore cylindrical portion  23 . 
     As shown in FIG.  3  and in the enlarged detail of FIG. 5, the shoulder  27  of the female contact-support body fits onto the cylindrical portion  23  by means of a slanted surface  28 , for example forming an angle of 45° with the longitudinal axis of the connector; the surface  28  is designed to come into contact and to form a seal with an opposite surface of the cylindrical wall  16  of the contact-support body  13  of the male connector, for example consisting of the internal corner  17 ′ at the fore end of the annular shoulder  17 . 
     In this connection, in conformity with this invention, the contact-support body  20  is made of elastically yielding elastomeric material, to provide a high sealing pressure when the corner  17 ′ of the shoulder  17 , during the screwing of the ring nuts  18  and  24  of the two connectors, comes into contact with and is pressed against the slanting surface  28  of the female contact-support body  22 . 
     For these and other scopes of this invention, it is therefore essential for the entire female contact-support body to be made of an elastomeric material which is capable of yielding elastically, both for the fitting and radial expansion of the female contacts  21 , as explained further on, and for the necessary watertight seal when the two connectors are coupled together. 
     Any plastic material, having appropriate elastomeric properties, can be used for the female contact-support body  20 ; for example, it is possible to use a thermoplastic elastomeric polyurethane (PUR), such as a polyester-polycaprolactone-based thermoplastic material, or a combination of diphenylmethane diisocyanate (MDI) and a polyester or a polyester-based polyol. 
     Excellent results have been obtained using an elastomeric polyurethane material having a hardness ranging from 92 to 96 Shore A, with a modulus of elasticity ranging from 8.2 to 8.6 MPa at an elongation equivalent to 50%. 
     Since, as it is being tightened, the ring nut  18  of the male connector pushes against the shoulder  17  of the rigid wall  16  of the body supporting the fixed contacts, while the ring nut  24  with its rim  26  pushes against the opposite side of the shoulder  27  of the support body  20  for the female contacts, made of elastically yielding elastomeric material, it is obvious that by tightening the two ring nuts  18  e  24  more or less it is also possible to vary the contact pressure between the sealing surfaces  17 ′ and  28 , thereby obtaining an even pressure over the entire peripheral surfaces of the two connectors. 
     Moreover, the elastic behaviour of the body  20  made of elastomeric material, supporting the female contacts, exerts a sufficient axial force on the threads  19  and  25  of the two ring nuts to prevent them from becoming accidentally unscrewed. 
     According to a further feature of the invention, as shown in greater detail in FIG. 3 of the accompanying drawings, the female contact-support body  20 , for each contact  21  is provided with a seat consisting of a through hole which comprises a cylindrical rear portion  30 , and a conical intermediate portion  31  which continues into a cylindrical fore portion  32  of smaller diameter, designed to allow the penetration or press-fitting of a contact pin of the male connector. 
     Each female contact  21  in turn is provided with a rear portion  33  designed to be clamped to an electrical conductor, which partially protrudes from the rear portion  30  of the housing hole, and also comprises a conical fore portion  34  which adapts to the internal tapering of the intermediate portion  31  of the housing hole. 
     The fore portion  34  of each female contact is made elastically yielding in a radial direction by a longitudinal slit  35 , and ends at its fore end with a diverging portion  36  designed to engage, or press-fitted with a certain degree of interference, into the fore end of the conical hole  31 , and coming to rest against an internal annular shoulder  37 . 
     In this way various substantially advantages are achieved, the first of these being that of facilitating an easy elastic splay at the fore end  34  of the female contact member  34 , upon the insertion of a male contact pin  14 , thanks to the elastic yielding of the elastomeric material with which the contact-support body  20  of the female connector is made. 
     By means of the slightly forced insertion of each female contact  21 , into its respective housing seat in the contact-support body  20 , and thanks to the elastic properties of the latter, it is also possible to achieve the further advantage of firmly retaining the contact  21 , once it has been inserted or press-fitted into its housing, during the assembling of the connector and moulding the outer casing, as well as the advantage of utilising the elasticity of the contact-support body itself to reduce the fatigue stress to which the female contacts are usually subjected during use. 
     As shown in the detail of FIG. 6, each hole housing the female contacts  21 , can be provided on the rear portion  30  with a detent  38  designed to snap, due to the elasticity of the material, into a slot  39  made on one edge of the rear portion  33 , designed to be clamped onto an electrical conductor, thereby preventing the female contact  21  from accidentally slipping out of its housing during assembling, regardless of the press-fitting degree of the contact itself into the elastomeric material of the contact-support body. 
     From what has been shown in the accompanying drawings, it will be clear that what is provided is an electrical connecting device having a male connector and a female connector, in which the female connector is characterised by comprising a contact-support body of elastomeric material, and by comprising means for retaining each female contact element, which exploit the elasticity of the elastomeric material itself to prevent the female contact element from accidentally slipping out during the assembling of the connector, as well as to allow a radial expansion of the same female contact element to providing good contact conditions for both connectors. 
     It is understood however that what has been described and shown in the accompanying drawings has been given purely by way of example in order to illustrate this invention, and that other modifications may be made, without deviating from the scope of the accompanying claims.