Abstract:
A coaxial cable assembly  2  consists of a plug coaxial connector subassembly  4  and a jack coaxial connector subassembly  6 . A plug connector  10  and a jack connector  50  are respectively mounted in molded plug and jack housings  20  and  60  respectively. The plug and jack housings  20  and  60  include a latching beam  66  that is attachable to a raised bum  26  on the other connector. The maximum force for disengaging the two subassemblies is greater than the engagement force because the bump includes a sloping forward surface  36  and a steep rear surface  38 . When used with connectors  10  and  50  that have equal mating and unmating forces, the total unmating force exceeds the mating force. The latches and the connectors are also positioned so that maximum mating forces of the two separate latching systems do not overlap, thus keeping the total mating force within acceptable limits.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related to coaxial electrical connectors. More particularly, this invention is related to mating plug and jack coaxial electrical connectors that are used to connect two coaxial cables and include a means for locking the two connectors together so that the force required to disconnect the plug and jack coaxial connectors is greater than the force required to mate the two mating connectors. Furthermore, this invention is related to the use of plug and jack coaxial connectors that are located in molded outer housings. This invention is also related to the use of coaxial electrical connectors in automotive applications. 
     2. Description of the Prior Art 
     Coaxial or RF plug and jack electrical connectors typically include means for connecting center conductors in separate coaxial cables and for connecting the outer shield or braid in the two cables. In some cases, the center conductor in one of the cables is connected directly to a socket terminal in the other coaxial connector, but often a pin is attached or crimped to the center conductor in the cable. The center contact and the braid contact in each connector or terminal are typically separated by a cylindrical dielectric surrounding the center contact. The outer contact is typically attached to the braid or shield of a coaxial cable by crimping a ferrule to the braid after the end of the cable has been prepared or stripped. 
     Once plug and jack coaxial connectors have been attached to sections of a coaxial cable, a number of conventional means have been employed to mate the plug connector to the jack connector. One connector may employ an outer ring with internal threads which can then be screwed to the mating connector with external mating threads. BNC style coaxial connectors employ a laterally facing pin or post on one connector that is captured within a slot on the mating connector. However, both of these coaxial connector configurations require that mating connectors must be mounted by rotating one connector relative to its mating connector. This approach may be satisfactory for many traditional applications, such as field assembly of two coaxial cables, for example connecting two cables in a commercial or residential building. However, when the coaxial cables are used in a larger component or subassembly, such as a harness in an automobile or motor vehicle, that is assembled in a large scale production environment, screwing the two coaxial connectors together is undesirable. Indeed assembly workers have complained that assembly of components in this manner can cause problems with carpal tunnel syndrome. 
     One alternative to coaxial connectors that are mated by screwing one connector to another, is to employ a snap-on or quick connect, quick disconnect configuration in which one coaxial connector is simply pushed into mating engagement with the other coaxial connector without mutual rotation. These prior art snap-on connectors typically include a plurality of screw machined or die cast spring fingers in a cylindrical configuration. Adjacent spring fingers are separated by slots and include mating ridges adjacent their free ends. The individual spring fingers can be radially when pushed onto a mating connector having a diameter that differs from the normal neutral position of the spring fingers. The spring fingers can be deflected inwardly or outwardly, depending on whether they a inserted into a bore in cylindrical sleeve or over the exterior of a cylindrical barrel. When the quick connect, quick disconnect, snap-on connectors are fully mated, the spring fingers are received within a groove or recess on the mating connector, so that the spring fingers return to their neutral position. Examples of coaxial connectors of this general type are shown in U.S. Pat. Nos. 4,017,139; 4,412,717; 5,842,872; and 6,036,540. Although conventional coaxial connectors of this type do not require rotational movement for mating, the disconnect force is typically approximately the same as the connection or mating force. Thus quick connect, quick disconnect coaxial connectors cannot be locked when mated, so that a significantly greater force is required to unmate or disconnect the coaxial connectors than was required to mate them. The fact that these prior art connectors cannot be locked together can cause problems when they are used in automotive applications or in harness assemblies for use in similar applications, because the connectors can be inadvertently dislodged during assembly or pulled apart when a force is applied to one of the coaxial cables, possibly as part of a later assembly operation. Vibration due to movement of the automobile or similar apparatus can also cause disengagement of the mated coaxial connectors. 
     Prior art coaxial connectors, of either the rotationally mated or snap-on type are not typically positioned within molded or plastic housings. Exceptions include multiple position connectors in which multiple coaxial cables attached to separate cables are mounted in multi-position housing that is to be mated with printed circuit board connectors located in an array. U.S. Pat. Nos. 4,008,941 and 5,842,872 show multi-position configurations of this type. However, these patents show coaxial contacts that are inserted into cavities that extend completely through one piece housings. U.S. Pat. No. 5,547,400 shows a printed circuit board type coaxial connector that is mounted in a two piece housing. 
     SUMMARY OF THE INVENTION 
     One of the objects of the invention disclosed and claimed herein is to provide a mating coaxial cable assembly in which the force required to unmate the two connectors is substantially greater than the force required to mate the two connectors so that the connectors can be said to be in a locked configuration when mated. Of course, it should still be possible to unlock or unmate the two connectors when sufficient force is applied, but this unmating force or the manipulation of the connectors to disconnect them, should not occur during their normal use, and it should require more than the application of a tensile force to disengage the two connector assemblies. 
     Another objective of this invention is employ an assembly that uses a standard, tested, and reliable mating interface or configuration for the coaxial connectors or terminals used to connect two coaxial conductors, such as two cables or one cable to be connected to one printed circuit board. A standard cable termination technique should also be retained. 
     This invention should also be suitable for use in automotive applications and for use on cables that are part of harness assemblies that are used in motor vehicles and other similar applications. When installed as part of an automotive assembly operation, the coaxial connectors comprising this invention should be mated and unmated in substantially the same manner as other electrical connectors. It is also important that the mating force of connectors used in such applications not exceed the mating force typically required to mate other noncoaxial electrical connectors used as part of the same assembly, so that they can be reliably installed and do not require special care on the part of the installer. 
     These and other objectives can be achieved by the coaxial connector assembly disclosed herein that includes a plug coaxial assembly matable with a jack coaxial assembly. The plug coaxial assembly includes a plug coaxial connector and a molded plug housing, which is formed by two plug housing components latched together around the plug coaxial connector. The jack coaxial assembly includes a jack coaxial connector and a molded jack housing, which is formed of two jack housing components latched together around the jack coaxial connector. The plug coaxial connector is latched to the jack coaxial connector when mated, and the molded plug housing is separately latched to the molded jack housing when the plug coaxial assembly is mated to the jack coaxial assembly. 
     In this assembly, the plug housing includes a plug latch and the jack housing including a jack latch. The plug latch is matable with the jack latch with an engagement force. The plug latch is unmated from the jack latch with a disengagement force, normally by deflecting a mating latch. The disengagement force is greater than the engagement force so that the plug coaxial connector and the jack coaxial connector can be locked in a mating configuration. 
     Spring fingers and a groove in mating coaxial connectors are positioned relative to latching members or housing surrounding these coaxial connectors so that a first mating force peak attributable to mating of the two coaxial connectors occurs prior to a second mating force peak attributable to mating the two latching members. The first and second mating force peaks do not overlap as the first subassembly is mated to the second subassembly, so that the maximum mating force can be maintained within acceptable limits. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view of mated plug and jack coaxial connector assemblies according to this invention, in which each assembly includes a coaxial electrical connector and a surrounding molded housing. 
     FIG. 2A is an exploded view of the main components of a plug coaxial connector. FIG. 2B shows the spring fingers positioned within the collar of the plug coaxial connector of FIG.  2 A. 
     FIG. 3 is a three dimensional view of the plug connector molded housing formed of two mating hermaphroditic housing components. 
     FIG. 4 is a three dimensional view of one of the plug connector housing components showing the exterior and the mating face of the plug connector housing component. 
     FIG. 5 is a three dimensional view of the plug connector housing component shown in FIG. 4 showing the interior of the housing component. 
     FIG. 6 is a view of a coaxial jack connector, partially broken away to reveal the center pin. 
     FIG. 7 is a three dimensional view of the molded jack connector housing showing the two mated hermaphroditic housing components. 
     FIG. 8 is a three dimensional view of one molded jack connector housing component showing the mating face and the exterior of the housing component. 
     FIG. 9 is a three dimensional view of the molded jack connector housing shown in FIG. 8 showing the interior of the housing component. 
     FIG. 10 is a view of a stripped end of a coaxial cable that can be attached to either or both of the plug and jack coaxial connector. 
     FIG. 11 is a graphical representation of the forces encountered as the plug connector assembly is mated to the jack connector assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The coaxial connector assembly  2  shown in FIG. 1 includes a first plug coaxial connector subassembly  4  and a second jack coaxial connector subassembly  6 . The plug coaxial connector subassembly  4  includes a plug coaxial connector  10 , shown in FIGS. 2A and 2B, that is positioned within a molded plug housing  20 , shown in FIGS. 3-5. The jack coaxial connector subassembly  6  includes a jack coaxial connector  50 , shown in FIG. 6, that is positioned within a molded jack housing  60 , shown in FIGS. 7-9. 
     The plug coaxial connector  10  includes a collar  14 , in which spring fingers  12 , which are shown in FIG. 2B, are located. These spring fingers  12  form part of a quick connect, quick disconnect feature and also serve to connect the braid or outer shield  104  of a coaxial cable  100 , as shown in FIG. 10, to another coaxial conductor segment. A ferrule  18  is crimped around the braid  104  to connect the braid to the outer conductor contact. A plug center contact  16 , in the form of a socket, is crimped to a center conductor  102 , that is separated from the braid  104  by a dielectric core  106 . A stripped end  108 , suitable for termination to the plug coaxial connector  10 , is shown in FIG.  10 . The plug coaxial connector  10  is of the type commercially available from Tycoelectronics (AMP) as an SMB In Line Plug connector Part Number 414946-1. 
     Plug connector  10  is positioned or mounted within the plug housing  20  to form the plug connector subassembly  4 . The preferred embodiment of plug housing  20  is formed of two mating hermaphroditic or identical one-piece molded housing components  22 , that are injection molded using a conventional molding thermoplastic material, such as acetal. These hermaphroditic housing components  22  can be snapped or latched together in surrounding relationship to the plug connector or terminal  10  that has been previously attached or crimped to a coaxial cable  100 . Although the two housing components  22  do not have to be identical, the manufacturing cost of the assembly is reduced if the same part can be used for both halves forming the molded plug housing  20 . 
     Housing component  22  includes a latching member in the form of a raised bump  26  located adjacent to a mating face  24 . The plug housing  20  will then have two oppositely facing mating or latching bumps  26  that comprise means for attaching or locking the plug connector subassembly  4  to the jack subassembly  6  to form the mated coaxial connector assembly  2 . Each plug housing component  22  also includes a molded housing latch  28 , in the form of a deflectable cantilever beam  28  and a latching shoulder  30  located on an opposite side of the molded plug housing component  22 . The latch  28  includes a head at its distal end that is configured to first be deflected by and then to mate with the latching shoulder  30  of the companion housing component that forms the other part of the plug housing  20 . Each plug housing component  22  also includes an alignment post  32  and an alignment pocket  34  which is dimensioned to receive an alignment post  32  on the companion hermaphroditic housing member. The housing latch  28 , the latching shoulder  30 , the alignment post  32 , and the alignment pocket  34  thus serve to position and latch the two housing components  22  into engagement surrounding a plug connector  10  positioned between the two housing components  22 . 
     Semicylindrical interior surfaces  40  define a compartment  42  into which the plug connector  10  will fit. The portion of the compartment  42  adjacent the mating face  24  has a dimension suitable for receiving the collar  14 , which comprises the portion of the plug connector  10  having the largest dimension. Two crush pads  44  in the form of raised molded surfaces will engage the exterior surface of the collar  14  to hold the connector  10  in position. These crush pads not only serve to locate the contact, but also function to prevent vibration or rattling. The ferrule  18 , crimped around the cable braid  104  at the rear of the connector  10  will fit within the smaller portion of the compartment  42  between the alignment post  32  and the alignment pocket  34 . An opening  46  is formed by two semicylindrical surfaces at the rear of the housing components  22  to form a cable exit  46  through which the terminated coaxial cable  100  will extend. 
     The latching bumps  26  protrude from upper and lower faces of the molded housing  20  and each includes an inclined or gently sloping forward surface  36  and a rear surface  38  that extends at a steeper angle relative to the housing face from which the bump protrudes. Rear surface  38  will function as a locking surface, making it more difficult to disengage a mating housing latch  66  on the jack housing  60 . In other words disengagement of latch  66  from bump  26  will require more force that the mating force required to deflect the latch  66  as it moves across the more gently inclined forward surface  36 . The rear surface  38  can even extend at a negative or back angle to enhance the locking engagement between the plug housing  20  and the jack housing  60 . USCAR specifications for connectors of this type require a mating force of less than 75 newtons and a disconnect force of more than 110 newtons. The front of the collar  14  of the plug coaxial connector  10  and the spring fingers  12  are slightly recessed relative to the mating face  24  of the housing  20 , but the front of the connector  10  is located between the mating face  24  and the beginning of the forward surface  36  of the raised bump  26 . As will be described later in more detail, the relative position of the bump  26  and the plug connector spring fingers  12  are important is assuring that the mating force between the two connector subassemblies  4  and  6  does not exceed a desirable upper limit. 
     The jack connector  50  comprising part of the jack connector subassembly  6  is shown in FIG.  6 . Jack connector  50  has a groove  52  that is spaced from its front beveled end, and the groove  52  extends completely around the exterior of the connector  50 . A center contact  56 , in the form of a pin is spaced from the other contact sleeve  54 , and the two separate conductors are separated by a dielectric, not shown. A mounting ring is located between the groove  52  and a rear section or ferrule  58  that is attached to the outer cable conductor or braid  104 . The jack connector  50  can be attached to the stripped end  108  of a coaxial conductor  100 , and in the preferred embodiment an existing jack connector available from Tycoelectronics (AMP) and sold as an SMB In Line Jack, Part Number 414948 is employed. 
     When the plug coaxial connector  10  is mated to the jack coaxial connector  50 , the spring fingers  12  are first cammed outwardly as they engage the beveled front of jack contact sleeve  54 . The deflected spring fingers  12  then slide along the exterior of the jack until the mating ridges on the ends of the spring fingers fit within the groove  52  so the that spring fingers  12  return to a neutral position. However, the disconnect force required to extract the spring finger ridges from groove  52  is approximately equal to the maximum connect force between the two connectors that occurs when the spring fingers are first outwardly deflected. Thus the plug coaxial connector  10  cannot be said to be locked to the jack coaxial connector  50 , even when the two connectors are fully mated. Also the connectors cannot be disengaged by simply pulling them apart, so that a tug on a cable cannot disconnect the two connectors. 
     The molded jack housing  60 , in which the jack connector  50  is positioned is formed by two hermaphroditic or identical jack housing components  62 , depicted in FIGS. 8 and 9. The jack housing component  62  is formed by injection molding, and a thermoplastic, such as acetal can be used to fabricated the one piece housing component  62 . FIG. 8 shows the exterior of one jack housing component  62 , and FIG. 9 shows details of the interior of the same component  62 . A deflectable cantilever beam latching member  66  extends forward from the mating face  64  of the jack housing component  62 . The latching member  66  has two arms, one end of which extends as an integral part of the housing component  62 , with an integral transverse arm, joining the two deflectable arms to form the deflectable cantilever latching member  66 . The two axially extending arms are spaced apart by a distance that is at least equal to the width of the raised bump  26  to which latching member  66  will be engaged. The transverse arm at the end of latching beam  66  will engage the forward bump surface  36  during mating and will snap behind the rear bump surface  38  when the plug housing  20  and the jack housing  60  are latched and locked in fully mating engagement. The timing of the engagement of the latching members  26  and  66  relative to the engagement of the plug connector  10  and jack connector So will be subsequently discussed with reference to FIG.  11 . 
     Each jack housing component  62  includes a cantilever beam housing latch  68  on one side and a housing latch shoulder  70  on the other side. The latch shoulder  70  is dimensioned to mate with the housing latch  68  when the two jack housing components  62  are assembled to form the two piece molded jack housing  60 . An alignment post  72  on each housing component fits within an alignment pocket  74  on the other housing component when the two hermaphroditic or identical housing components  62  are assembled in at least partially surrounding relationship to the jack connector  50 . 
     As shown in FIG. 9, each jack housing component  62  includes semi cylindrical mounting surfaces  76  forming an interior compartment  78  in which the rear portion of the jack connector  50  can be positioned. A crush ring  80  is located in a central recess in which the mounting ring at the center of the jack connector  50  is positioned. With the jack connector positioned within the compartment  78  in this manner, the front outer contact portion  54  and the groove  52  will extend beyond the housing face from which the latches  66  protrude. Sidewalls  88  also extend from this face so that the sidewalls  88  and the latches  66  form a cavity to receive the mating portion of the plug connector from which the raised bumps  26  extend. The front contact portion  54  will also be located within this cavity and will be inserted into the collar portion  14  of the plug connector  10  in the fully mated configuration. 
     The jack connector housing components  62  has have two sets of rails for mounting the entire coaxial connector assembly on a protruding member that will fit between the rails. Plastic member having fur tree mounting posts, sometimes colloquially referred to as Christmas trees, insertable through holes in bulkheads, typically included a rib extending parallel to the bulkhead. This rib can be received between the two sets of rails  84  and  86  on the jack connector housing  60  so that the entire assembly can be firmly mounted on a bulkhead. The first rail  84  is a continuous rail, shown in FIG. 9 that is located at the base of the housing latch  68 . The second set of rails is formed by two rails  86  located on opposite sides of the housing latching shoulder  70 , as shown in FIG.  8 . This provides space for the latching beam  68  on the opposite housing component  62  to engage the opposed latching shoulder  70 . A protrusion  88  at the end of rail  86  provides a means for securing a latching rib mounted to the bulkhead. A conventional latching rib of this type can be deflected outward into engagement with the protrusion  88  by a sloping surface on the adjacent side of the housing component  62 . The rails  84 ,  86  can be mounted on the rib either before or after the plug connector subassembly  4  is mated to the jack connector assembly  6 . 
     One of the principal goals of this coaxial connector assembly is to provide plug and jack connectors that can be locked together so that it requires significantly greater force to inadvertently unmate the connectors than is required to mate the connectors, but at the same time to keep the overall mating force between the connectors within acceptable limits. In order to accomplish this, the mating force peak between the plug connector  10  and the jack connector  50  should not overlap the mating force peak between the latch  66  and the raised bump  26 . This is accomplished by positioning the plug and jack connectors  10 ,  50  in the housings  20 ,  60  so that the spring fingers  12  have been deflected to their maximum before the jack latches  66  engage the forward surface  36  of the raised bump  26 . As shown in FIG. 11, the peak force between the plug connector  10  and the jack connector  50  occurs at point A, well before the peak engagement force between the latching members  26 ,  66  at point B. As shown in FIG. 11 there is initially negligible mating force between the two connectors until the spring fingers  12  are deflected outward upon engagement with the front of the jack connector  50 , at which the mating force increases until the spring fingers  12  are at their maximum deflection, corresponding to position A in FIG.  11 . As the plug and jack connectors continue to move to a fully mated configuration, there a frictional force, dependent upon the spring force exerted by the deflected spring, is still present. This frictional force is, however, significantly less than the peak force at A. When the lathing beam  66  engages the forward surface  36  on the plug, an engagement force between the two mating connector housing increases until a peak force is reached at B. corresponding to maximum deflection of latching beam  66 . The latching beam then snaps behind the rear surface  38  on the bump  26 . Since the peak mating force between the two connectors occurred at point A, well before the peak engagement force due to deflection of the molded cantilever beam  66  at B, these two force peaks are not additive, and the maximum mating force can remain within acceptable limits. However, the disengagement force between the beam  66  and the bump  26  is even larger because of the slope of the rear surface  38 , so that the two connectors subassemblies  4 ,  6  can be locked together and cannot be disengaged by the application of a tensile force to either or both coaxial cables. 
     The invention disclosed by the representative embodiment is especially suitable for use for connecting two coaxial cables. However, the same approach can be used to connect a coaxial cable with a printed circuit board connector. The representative embodiments depicted herein are also intended for use with a single connector assembly, but multiple coaxial lines could also be connected employing the same approach. The invention is therefore not limited to use in the preferred and representative embodiment depicted herein, and equivalent structures apparent to those of ordinary skill in the art could employ the same invention that is defined by the following claims.