Abstract:
A connection device comprises first and second connectors. The first connector has a sleeve having axially extending slots at a distal end to define tines yieldable resiliently inward, and a resilient seal encircling the sleeve proximally of the slots. The second connector has a shroud dimensioned to receive the distal end of the first connector sleeve within the shroud and to engage the first connector resilient seal when the sleeve is fully received within the shroud.

Description:
BACKGROUND  
       [0001]     The invention relates to connectors, and especially to a connector for coaxial cables.  
         [0002]     U.S. Pat. No. 4,925,403 to Zorzy and U.S. Pat. No. 6,827,608 to Hall et al., which are incorporated herein by reference in their entirety, show connection devices for coaxial cables. In each of those devices, one connector has a center pin, formed as an extension of the center conductor of a coaxial cable, surrounded by a tubular metal shroud. The mating connector has a center socket surrounded by a dielectric component, which is surrounded by a metal sleeve with a clearance between the dielectric component and the sleeve. The sleeve is slotted at its distal end to form a ring of tines or beams joined together by an unslotted base part of the sleeve. The tines are resilient, and when the sleeve is inserted into the shroud, thickened tips on the tines snap into a groove or trepan formed inside the shroud. The connected sleeve and shroud form the electrical connection for the shroud of the coaxial cable.  
         [0003]     With this form of connection device as generally used, proximal or base ends of the slots in the sleeve are exposed through a gap between the sleeve and the distal end of the shroud. As a result, water and other contaminants can enter the connection, and can penetrate the space between the sleeve and the center conductor. Contaminant penetration can cause corrosion of the connection device, loss of electrical continuity either directly from contaminant penetration or from the formation of corrosion products, and changes to the electrical impedance of the connection that may interfere with the transmission of signals along the coaxial cable. In addition, the lack of physical continuity of the conductive shroud due to the slots, especially if the two halves of the connection device are not precisely coaxial so that the slots form an asymmetrical pattern, can allow unacceptable levels of signals to radiate to the external environment. The radiating signal may cause interference with neighboring devices, and the loss of signal energy may impair signal transmission along the coaxial cable.  
       SUMMARY  
       [0004]     According to one embodiment of the invention, there is provided a connector, comprising a sleeve having axially extending slots at a distal end to define tines yieldable resiliently inward, and a resilient seal encircling the sleeve proximally of the slots.  
         [0005]     According to another embodiment of the invention, there is provided a connector, comprising a sleeve having axially extending slots at a distal end to define tines yieldable resiliently inward, wherein the tines are stepped along their length.  
         [0006]     According to another embodiment of the invention, there is provided a connection device, comprising a first connector having a sleeve with axially extending slots at a distal end to define tines yieldable resiliently inward and a resilient seal encircling the sleeve proximally of the slots and a second connector having a shroud dimensioned to receive the distal end of the first connector sleeve within the shroud and to engage the first connector resilient seal when the sleeve is fully received within the shroud.  
         [0007]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.  
         [0009]     In the drawings:  
         [0010]      FIG. 1  is an axial section through a pin coaxial connector according to an embodiment of the invention.  
         [0011]      FIG. 2  is an axial section through a socket coaxial connector according to an embodiment of the invention.  
         [0012]      FIG. 3  is an axial section through a connection device comprising a pin coaxial connector according to  FIG. 1  and a socket coaxial connector according to  FIG. 2  connected together.  
         [0013]      FIG. 4  is a perspective view of part of the socket coaxial connector shown in  FIG. 2 .  
         [0014]      FIG. 5  is a view similar to  FIG. 1  of an alternative form of pin coaxial connector.  
         [0015]      FIG. 6  is an axial section through part of an alternative form of socket coaxial connector. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0017]     Referring to the drawings, and initially to  FIGS. 1 and 2 , one form of connection device according to an embodiment of the invention, indicated generally by the reference numeral  20 , comprises a pin coaxial connector  22  (shown in  FIG. 1 ) and a socket coaxial connector  24  (shown in  FIG. 2 ).  
         [0018]     Referring to  FIG. 1 , the pin coaxial connector  22  may be a panel mount connector arranged to be mounted on or through the wall of an electronics module (not shown). The pin coaxial connector  22  comprises a central pin  26 , which is mounted in a dielectric  32  that is received in a bore  33  of a metal shroud  34  coaxial with the central pin  26 . The shroud  34  may be electrically bonded to the wall of the electronics module, or may be carried through the wall in an insulating bushing (not shown). The fittings for attaching the connector  22  to the electronics module may be conventional and, in the interests of simplicity, are not shown in  FIG. 1 . Various methods of attaching the connector  22  to the electronics module are known, and in the interests of conciseness will not be further described here.  
         [0019]     The inside of the shroud  34  has a cavity  36  into which the central pin  26  projects. The cavity  36  terminates at a reference plane  38  defined partly by the cut end of the dielectric  32 , and partly by a flat, radially extending wall  40  of the shroud  34 , extending outward from the bore  33 .  
         [0020]     The cavity  36  is rotationally symmetrical about the axis defined by the central pin  26 . From the reference plane  38  toward the distal end of the connector  22 , the cavity  36  is defined by a trepan  42 , a ramp  44  sloping inward from the trepan, a neck  46  smaller than the trepan  42  and slightly larger in diameter than the bore  33 , a lead-in taper  48  that widens from the neck  46  towards the distal end, and a cylindrical stabilizer section  50 . The distal end of the shroud  34  is formed by a seal lip  52  defining the outermost part of the stabilizer section  50 .  
         [0021]     Referring now to  FIG. 2 , the socket coaxial connector  24  has a center contact  60  that is dimensioned to be a push fit at a distal end on the central pin  26  of the pin coaxial connector  22  shown in  FIG. 1 . The other, proximal end of the center contact  60  is a push fit on a central pin  62  that is a continuation of a center conductor of a coaxial cable  64 . An outer conductor  66  and dielectric  68  of the coaxial cable  64  may be cut back, leaving the end of the center conductor exposed to form the central pin  62 . Alternatively, a separate pin  62  may be electrically bonded to the center conductor of the coaxial cable  64 .  
         [0022]     A metal sleeve  70  has a proximal end that fits over and is electrically bonded to the outer conductor  66  of the coaxial cable  64 , and a distal end that projects slightly beyond the distal end of the center contact  60 . The space between the center contact  60  and the sleeve  70  is occupied by dielectric components  72 ,  74  that serve both to maintain the alignment and spacing between the center contact  60  and the sleeve  70  and to maintain the correct transmission line impedance to match the coaxial cable  64 . As shown in  FIG. 2 , one dielectric component  72  is a washer trapped between the end of the coaxial cable  64  and a shoulder  76  on the inside of the sleeve  70 . Another dielectric component  74  is retained by hooks  78  that catch in a groove  80  on the inside of the sleeve  70 , and has a shoulder  82  that engages a shoulder  84  on the center contact  60  to keep the center contact  60  in position in the connector  24 . For a reason that will be explained below, there is a clearance  86  between the dielectric component  74  and the inside of the sleeve  70  at the distal end of the sleeve  70 . Alternatively, other configurations and arrangements of the dielectric components are possible, including many suitable configurations and arrangements that are known to the person skilled in the art.  
         [0023]     The sleeve  70  is encircled by a soft elastomeric gasket  90  that is retained in place between a shoulder  92  at the proximal end of the gasket  90  and a stabilizer shoulder  94  at the distal end of the gasket. The shoulder  92  extends approximately the full radial height of the gasket  90 . The shoulder  94  extends only part of the height of the gasket. The length from the distal end of the gasket  90  to the distal end of the sleeve  70  is slightly less than the length from the tip of the seal lip  52  to the reference plane  38  of the pin coaxial connector  22  shown in  FIG. 1 . The radially outer face of the stabilizer shoulder  94  has a radius just less than the radius of the stabilizer section  50 . On the distal side of the stabilizer shoulder  94 , the sleeve  70  is encircled by a metal EMI shield ring  96 . The EMI shield ring  96  has a cylindrical base  98  that fits snugly around the sleeve  70 , and a flange  100  that is attached to the distal end of the base and slopes outwards and back towards the proximal end. The EMI shield ring  96  may be divided by a single narrow slit (not shown) to allow the EMI shield ring to expand and contract in the circumferential direction.  
         [0024]     The distal end of the sleeve  70  is divided into tines  102  by slots  104 , best seen in  FIG. 4 . The slots  104  open through the distal end of the sleeve  70 , and have closed roots  106  just short of the stabilizer shoulder  94 . As may be seen in  FIG. 4 , the width of the slots  104  increases from the roots  106  to the open ends of the slots  104 . In the embodiment shown in  FIG. 4 , each slot  104  has two sections of approximately equal length, each section having straight, parallel walls, separated by a step  108 . The step  108  is not tapered, but the concave angles between the step  108  and the wider part of the slot  104  may be rounded to a radius that is a substantial part of the width of the step  108 . It has been found that a configuration with four slots  104  is easy to manufacture and can give close to optimal performance for at least some connector configurations. However, other numbers of slots may be used in appropriate configurations of the connector  24 . Slots with more than one step  108  may be used in appropriate configurations of the connector  24 .  
         [0025]     The thickness of the tines  102  decreases in steps  110  from the roots  106  of the slots  104  to the distal end of the sleeve  70 . The tips  112  of the tines  102  are formed as outward thickenings of the tines  102 , with ramps  114  on the proximal faces. In the embodiment shown in  FIG. 4 , the length of the tines  102  between the stabilizer shoulder  94  and the beginnings of the ramps  114  is divided into three approximately equal straight sections  116  by two steps  110 . The straight sections  116  are cylindrical, and the steps  110  are gently sloped. Because of the length of the tips  112  of the tines  102 , the step  108  in the width of the slot  104  is in the most distal of the straight sections  116 , just distal of the more distal step  110 .  
         [0026]     The steps  108 ,  110  increase the effective flexibility of the tines  102 , by concentrating bending stresses at the steps, and thus allow shorter tines  102  for the same radial yield characteristics of the tips of the tines than would be possible with straight or smoothly tapering tines of the same thickness and strength. The steps  108 ,  110  thus allow a correspondingly shorter connector  24 .  
         [0027]     When the socket coaxial connector  24  is inserted into the pin coaxial connector  22 , the tips  112  of the tines  102  fit inside the stabilizer section  50  with a clearance. The tine tips  112  then contact the lead-in taper  48 . The taper angle of the lead-in taper  48  is sufficiently gentle that an axial force urging the connectors  22 ,  24  together will result in the lead-in taper  48  deflecting the tines  102 , permitting further insertion of the socket center connector  24  into the pin center connector  22 . The clearance  86  between the tines  102  and the dielectric component  74  permits the tines  102  to deflect.  
         [0028]     As the socket connector  24  is inserted, the EMI shield ring  96  enters the stabilizer section  50 . The stage of the insertion at which this and other events occur, and the order in which they occur, may vary depending on the exact design of the connectors  22 ,  24 . The EMI shield ring  96  may be dimensioned so that when the connectors  22 ,  24  are exactly coaxial the outer edge of the EMI shield ring  96  does not quite touch the internal surface of the stabilizer section  50 . The EMI shield ring  96  is positioned axially so as to rest against the lead-in taper  48  when the connectors  22 ,  24  are fully engaged. Alternatively, the EMI shield ring  96  may be dimensioned so that its outer edge is deflected slightly by the tapered lead-in section of the stabilizer section  50 , and then slides along the internal surface of the stabilizer section  50 . The EMI shield ring  96  may then be positioned axially so as to rest either against the lead-in taper  48  or against the internal surface of the stabilizer section  50  when the connectors  22 ,  24  are fully engaged. The shroud  34 , EMI shield ring  96 , and sleeve  70  thus provide a continuous electrical path without gaps, or with only a single small gap because of the slit in the EMI shield ring, between the outer conductor  66  of the coaxial cable  64  and the shroud  34 . If the connectors  22  and  24  are not exactly coaxial, contact between the seal lip  52  and the sloped front surface of the EMI shield ring  96  will guide the connectors into alignment.  
         [0029]     As the socket center connector  24  is inserted, the center contact  60  of the socket center connector starts to slide onto the central pin  26  of the pin center connector  22 .  
         [0030]     When the distal ends of the tine tips  112  reach the inner, narrow end of the lead-in taper  48 , the tine tips  112  move onto the cylindrical surface of the neck  46 . The diameter of the neck  46 , compared with the undeflected diameter of the tine tips  112 , determines the minimum sizes of the width of the slots  104 , and of the radial clearance  86  between the dielectric component  74  and the tines  102 , to permit the necessary radial deflection of the tines  102 .  
         [0031]     The seal lip  52  of the pin center connector  22  continues past the EMI shield ring  96  and over the socket stabilizer shoulder  94 . The socket stabilizer shoulder  94  permits the stabilizer section  50  to slide over it without binding but with minimum play. The socket stabilizer shoulder  94  and the stabilizer section  50  can thus cooperate to ensure that the connectors  22 ,  24  remain correctly aligned. The facing edges of the socket stabilizer shoulder  94  and/or the seal lip  52  are chamfered or rounded, so that they will deflect each other into alignment, achieving trouble-free insertion of the socket stabilizer shoulder  94  into the stabilizer section  50 , rather than catching on each other if the two connectors are not already exactly aligned. Because the two connectors are already approximately aligned by the EMI shield ring  96 , only a slight chamfer or rounding is typically required. After crossing the socket stabilizer shoulder  94 , the seal lip  52  presses into the gasket  90 , which deforms slightly and forms a fluid-tight seal between the shrouds  34  and  70 , and thus between the coaxial cables  64  and the electronics module.  
         [0032]     As the tine tips  112  pass the neck  46 , the tine tips expand into the shroud retention trepan  42 . In the fully engaged position, as shown in  FIG. 3 , the tine tips  112  are urged outwards into the retention trepan  42  by the resilience of the tines  102 . The ramps  114  on the rear edges of the tine tips  112 , resting on the ramp  44 , then produce a wedging action that urges the distal end of the socket coaxial connector  24  into contact with the reference plane  38  of the pin coaxial connector  22 . The wedging action is sufficiently strong to overcome the restoring force from the compression of the gasket  90  by the seal lip  52 .  
         [0033]     When the connectors  22  and  24  are to be separated, the tines  102  are inaccessible within the shroud  34 , and cannot be directly compressed radially. However, an axial force can be applied by pulling the connectors  22 ,  24  apart. The ramp  44  then acts to deflect the tine tips  112  inwards as they are withdrawn axially. Therefore, the angle at which the ramps  114  on the tine tips  112  rides on the ramp  44  is chosen to be sufficiently close to 45°, and the surface finish of the ramps  44  and  114  is chosen to have a sufficiently low coefficient of friction, that the ramps  44  and  114  can both generate an axial force from a radial force and generate a radial force from an axial force. In a practical embodiment, the cone half-angle of the ramp  44  is around 30° and the cone half-angle of the slope  114  on the tine tips  112  is around 40°, so that the angle at the outer edge of the ramps  114  slides on the ramps  44 . Alternatively, depending on the relative angles of the ramps  44  and  114 , the ramps  114  of the tine tips  112  may lie flat on the ramp  44  of the shroud  34 , or the angle between the ramp  44  and the neck  46  may bear on the ramps  114 . The material of the gasket  90  is sufficiently soft compared with the stiffness of the tines  102  that the resilience of the gasket does not overcome the resilience of the tines and cause undesired separation of the connectors  22 ,  24  in use.  
         [0034]     The EMI shield ring  96  may be trapped between the socket stabilizer shoulder  94  and the lead-in taper  48  with substantially no play, or with the flange  100  of the EMI shield ring pressed against the lead-in taper. If the EMI shield ring  96  is compressed against the lead-in taper  48  so as to exert a significant axial restoring force, that restoring force contributes to the balance of forces on the tine tips  112 , and the tines  102  are made sufficiently stiff that the combined axial force from the EMI shield ring  96  and the gasket  90  does not overcome the resilience of the tines  102  and cause undesired separation of the connectors  22 ,  24  in use.  
         [0035]     When the connectors  22  and  24  are separated, an axial force is exerted sufficient that the ramp  44  deflects the tine tips  112  inward to pass through the neck  46 , and to pull the central pin  26  out of the center contact  60 . Another dielectric component  74  is retained by, and has a to keep the center contact  60  in position in the connector  24 . The dielectric component  74  acts as a retaining clip for the center contact  60 , with the shoulder  82  on the dielectric component  74  engaging the shoulder  84  on the center contact  60  and the hooks  78  on the dielectric component  74  catching in the groove  80  on the inside of the sleeve  70 . The center contact  60  thus remains in the socket coaxial connector  24  and is not pulled out with the central pin  26 . The outer lip of the flange  100  of the EMI shield ring  96  may be shaped, for example, rounded, so that the EMI shield ring does not bind on the stabilizer section  50 .  
         [0036]     The connection device shown in  FIG. 3  joins a pin coaxial panel mount connector to a socket coaxial connector on a coaxial cable. Alternatively, the connection device may be applied to other configurations, including a device where two coaxial cables, both having pin coaxial connectors, are joined by an adaptor having two socket coaxial connectors, or vice versa, or a connection device where two coaxial cables are connected using a pin coaxial connector on one cable and a socket coaxial connector on the other cable, or a device with a socket coaxial panel mount connector, or with either or both connectors mounted or attached in some other way.  
         [0037]     Referring to  FIG. 5 , in an alternative form of pin coaxial connector  122  according to an embodiment of the invention mounted on a coaxial cable, the central pin  126  of the pin coaxial connector is formed by a contact  128  that is a push fit on a central pin  62  formed by the center conductor of the coaxial cable  64 , similarly to the center contact  60  shown in  FIG. 2 . The outer conductor  66  of the coaxial cable  64  is received in, and electrically bonded to, a metal sleeve  130 . The front end of the sleeve  130  is received in, and electrically bonded to, a stepped bore  132  in the rear end of a metal shroud  134  coaxial with the central pin  126 . An insulator  136  is trapped between the sleeve  130  and a step  138  in the bore  132 , and the contact  128  is retained behind the insulator  136 . The insulator  136  occupies the narrowest portion of the bore  132 . Forward of the insulator  136 , the bore  132  opens out into a cavity  137 , the shroud  134  and the cavity  137  having the same configuration as the shroud  34  and cavity  36  shown in  FIG. 1 . The pin coaxial connector  122  shown in  FIG. 5  can connect to the socket coaxial connector  24  shown in  FIG. 2  in the same way as the pin coaxial connector  22 .  
         [0038]     Various materials may be used for the connectors  22 ,  24 ,  122 . However, for the sleeve  70  of a connector  24  comparable to the Series SMP interface specified in United States specifications DSCC 94007 and DSCC 94008, and having the shape shown in  FIG. 4 , Beryllium-copper alloy according to ASTM-B-196, Uns No. C17300, Temper TD04(H), heat treated after machining to Temper TH04(T), finish gold over nickel plate, may be preferred. This material is found to have a high level of fatigue resistance that is desirable for the tines  102  especially in applications involving a large number of connections and disconnections. If the material of the tines  102  softens or deforms permanently, the force required for disconnection may become low, and the connectors and may become disengaged inadvertently. If the material of the tines  102  work-hardens, the force required for connection and disconnection may become undesirably high. For a connector of the size of the Series SMP interface, with a diameter of around 0.130″ (3.3 mm) across the tine tips  112  in the unstressed state, the shape of the tines  102  shown in  FIG. 4  is found to be satisfactory. However, for connectors of other sizes, or different performance requirements, other shapes, for example, different numbers or positions of the steps  108 ,  110 , different widths and thicknesses for the slots  104  and the sections  116 , and different angles for the various tapered surfaces  110 ,  114 , etc. may be preferred.  
         [0039]     Referring to  FIG. 6 , an alternative form of sleeve  170  for use in a connector according to an embodiment of the invention is generally similar to the sleeve  70  shown in FIGS.  2  to  4 , except that the sleeve  170  has five slots  172  defining five tines  174 , and the slots  172  are evenly tapered, forming a V-shape with a rounded root  176 . The tines are tempered to spring temper after splaying. The configuration of sleeve  170  shown in  FIG. 6  is suitable for a connector of the size of a Series WSMP interface, with a diameter of around 0.125″ (3.125 mm) across the tine tips  178  in the unspread state and around 0.130″ (3.3 mm) in the spread and tempered state.  
         [0040]     Stepped slots such as the slots  104  shown in  FIG. 4  may be formed by sawing parallel-sided slots in the sleeve  70 . V-shaped slots such as the slots  172  shown in  FIG. 6  may be formed by cutting the slots in a V shape. In each case, the tines  102 ,  174  may then be splayed out so as to increase the effective diameter at the tip by several percent. The minimum diameter to which the tines can be compressed to pass through the neck  46  is set by the diameter before spreading and the amount of material cut away in forming the slots. For example, for a Series SMP or Series WSMP interface, the neck  46  has an internal diameter of 0.116″±0.002″ (2.95 mm±0.05 mm), so the minimum diameter of the compressed tines  102 ,  174  may be no greater than 0.114″ (2.90 mm).  
         [0041]     The greater number of slots  172  makes the tines  174  more flexible, because each tine spans a smaller arc of a circle and is thus less stiffened by its transverse curvature. The smoothly tapered slots  172  make the tines  174  less flexible, by eliminating the concentration of stress, and thus of flexing, at the shoulder  108 . However, by eliminating the concentration of stress, the tines  174  with smoothly tapered slots  172  may be less subject to fatigue, and may have a longer working life. In addition, the tapered slots  104 ,  172  can reduce RF leakage, because even if the EMI shield ring  96  does not completely prevent RF leakage, only the narrow roots of the slots are exposed outside the shroud  34 ,  134 .  
         [0042]     Referring to  FIG. 7 , a socket coaxial to socket coaxial bullet connector  200  according to an embodiment of the invention has two ends each of which is generally similar to the connector  24  shown in  FIG. 2  from its distal end to the flange that defines the shoulder  92  that supports the gasket  90 . However, in the bullet connector  200 , the sleeve  202  has a central flange  204  that defines shoulders  92  on both end faces, and has two distal ends beyond the two shoulders  92 . Instead of each socket coaxial connector having a center contact  60 , as shown in  FIG. 2 , that is then bonded to the exposed end  62  of the center wire of the coaxial cable  64 , the bullet connector  200  has a center shaft  208  with a center contact  210  formed on each end. Other features of the bullet connector  200  can be understood by comparing  FIG. 7  to  FIG. 2  and referring to the text describing FIGS.  2  to  4  and, in the interests of conciseness, that description is not repeated here. It can also be understood from a comparison of  FIGS. 5 and 7  how to construct a socket coaxial to pin coaxial or pin coaxial to pin coaxial bullet connector.  
         [0043]     Various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.  
         [0044]     For example, although the shroud  34 , the sleeve  70 , and the EMI shield ring  96  are described as being of metal, any or all of them may be made of any material, including materials to be developed hereafter, that provides the desired electrical conductivity and mechanical strength. Alternatively, any or all of the shroud  34 , the sleeve  70 , and the EMI shield ring  96  may be structures comprising electrically conductive and other components.  
         [0045]     Although the invention has been described with reference to embodiments of coaxial electrical connectors, those skilled in the art will understand how features of different embodiments may be combined in a single device as may be appropriate for a specific purpose, and will understand that various aspects of the invention may be applied to other forms of connectors. For example, the combination of the shroud cavity  36  and the fingers  102 ,  174  may be used to provide a releasable mechanical connection in devices other than a coaxial electrical connector.