US 3562696 A
Description (OCR text may contain errors)
Feb. 9., 1971 BARNHART ETAL 3,562,696
I MULTICONTACT CONNECTOR HAVING IMPROVED INSERT 5 Sheets-Sheet 1 Filed Jan. 17, 1969 Feb. 9, 1971 I BARNHART ETAL 3,562,696
MULTICONTACT CONNECTOR HAVING IMPROVED INSERT 3 Sheets-Sheet 2 Filed Jan. 17, 1969 MULTICONTACT CONNECTOR HAVING IMPROVED INSERT Filed Jan. 17, 1969 9, 19.71 H. E. BARNHART ET 3 Sheets-Sheet 3 United States Patent 3,562,696 MULTICONTACT CONNECTOR HAVING IMPROVED INSERT Harry Edward Barnhart, Hummelstown, and Gilbert Douglas Ferdon, Harrisburg, Pa., assignors to AMP Incorporated, Harrisburg, Pa.
Filed Jan. 17, 1969, Ser. No. 791,977 Int. Cl. H011 13/52 U.S. Cl. 339-60 1 Claim ABSTRACT OF THE DISCLOSURE .Multicontact electrical connector part, which is engageable with a complimentary connector part, has a shell member and an insert in the shell. The insert is axially movable, to a limited extent, in the shell and is resiliently biased in the direction of the mating face of the insert. When the connector part is mated with the complimentary part, and the mating face of the two connector parts are pressed against each other, the insert is moved rearwardly with concomitant partial compression of the spring so that the spring functions to bias the insert against the insert of the mating connector part.
BACKGROUND OF THE INVENTION A conventional type of multicontact electrical connector comprises a shell member, which is usually of metal, and an insert of an insulating material in the shell. Contact cavities extend through the insert from the rearward face thereof to the mating face and electrical contact terminals are mounted in the cavities. When a connector part of this type is mated with a complimentary connector part, the contact terminals in the two connector parts are engaged with each other thereby to complete the circuits of the wires connected to the contact terminals.
High quality connectors of the type described above, particularly those intended for use in aircraft or under other critical circumstances, are usually of the sealed type in which the individual contact terminals in both connector parts are sealed from the atmosphere. Such sealing requires that sealing means of some sort be provided for each of the contact cavities in the inserts at both ends of the cavity. The rearward ends of the cavities are often sealed by providing constrictions in the cavities which bear against the wires extending to the terminals mounted in the cavities and prevent the entrance of corrosive gages or the like into the cavities. The forward ends of the cavities, which open into the mating faces of the inserts, are usually sealed by assuring that when the connector parts are mated, the two mating faces 'will be pressed firmly against each other so that the resilient material, of which the mating faces are formed, will be compressed to provide a seal surrounding each of the cavities.
The present invention is directed to the achievement of an improved sealed connector. It is an object of the invention to provide an improved multicontact electrical connector. A further object is to provide a sealed electrical connector having means for maintaining the interface seal of the connector not withstanding exposure to adverse environmental conditions. A still further object is to provide a connector having means for offsetting the deleterious affects of aging of the insert. A still further object is to provide a connector having means for compensating for the affect of compression set in the insert material. A further object is to provide a connector having means for maintaining substantially complete mating of the contact terminals in the connector parts when the parts are engaged with each other and for maintainice ing the parallelism of the contact terminals in the connector parts.
These and other objects of the invention are achieved in a preferred embodiment thereof comprising a connector part having a metallic shell member and an insulating insert in the shell. The mating face of the insert is of a compressible material, such as a silicone rubber, so that when the connector part is mated with a complimentary connector part, the mating faces of both parts will be compressed to provide sealing means in surrounding relationship to each of the contact terminals in the connector parts. The insert is resiliently biased in the direction of its mating face by means of a spring interposed between a shoulder on the insert and a shoulder on the shell. The strength of this spring is such that when the part is engaged with a complimentary connector part the mating face of the insert will be compressed and the insert will move rearwardly in the shell against the biasing force of the spring. During use of the connector, if the insert material at the mating face thereof should change its physical properties, as a result of aging or temperature cycling and thereby lose some of its ability to be compressed against the mating face of the complimentary connector part, the stored energy of the spring will continue to urge the mating face against the mating face of the complimentary part thereby maintaining the interfacial seal of the connector.
In the drawing:
FIG. 1 is a perspective view of a connector assembly in accordance with the invention showing the two parts of the connector disengaged from each other and showing some of the parts exploded from the connector shells to reveal their structural details.
FIG. 2 is a sectional side view of a connector assembly in accordance with the invention showing the positions of the parts prior to engagement of the connector parts with each other.
FIG. 3, is a fragmentary view similar to FIG. 2, but on an enlarged scale, showing the parts engaged with each other.
Referring first to FIGS. 1 and 2 a connector assembly in accordance with the invention comprises a plug part 2 and a receptacle part 4. The plug comprises an upper shell section 6 and a lower shell section 8, these shell sections being integral with each other by means of a web portion 12 and an integral mounting flange 10. Shells of this type are usually of metal and may conveniently be manufactured by conventional die casting techniques. A plurality of keys 14 are mounted in the web portion 12 of the plug 2 and are adapted to enter 'key receiving openings 14 in the web portion 12 of the receptacle 4. These keys may be individually oriented in any one of several possible orientations so that the two parts of a connector assembly can be keyed to each other in a manner such as to prevent mismating of one connector plug with the receptacle of a different connector assembly. The copending application of Harry 'E. Barnhart et al., Ser. No. 669,739, now U.S. Pat. 3,491,330 discloses and claims a preferred method of mounting the keying means 14, 14 in the web portions in the connector shells.
The upper shell section 6 is of generally polygonal cross-section and has an opening extending therethrough from its rearward end 16 to its forward end 18 for reception of the insert assembly 38 described below. As viewed in axial cross-section (FIGS. 2 and 3) this opening extends inwardly with a uniform cross-Section 20 from the rearward end 16 of the shell and is constricted intermediate its ends by a shoulder 22. Adjoining the shoulder 22 is a relatively short section 24 of uniform cross-section, another rearwardly facing shoulder 26 at the end of the uniform cross-section portion 24, a further very short 3 reduced cross-section port 28, a diagonally extending shoulder 30, and a final relatively short portion of uniform cross-section 32. The forward portion 34 of the opening has sidewalls which diverge slightly from the longitudinal axis of the shell for draft purposes.
The insert assembly 38 comprises a forward portion 44 which is of a resilient rubber-like material, an intermediate section 46 which may be of a relatively firm plastic material, and a rearward or grommet portion 48 which is again of a rubber-like material. Contact cavities extend through the insert from the rearward face 40 to the mating face 42 thereof and electrical contact sockets 52 are mounted in these cavities in the plug portion of the connector assembly as shown. It will be understood that the principles of the invention can be employed if a wide variety of shells and insert configurations, the disclosed configurations being of the type commonly used for connectors employed in critical air-craft installations.
The rearward section 48 of the insert assembly has a circumferentially extending collar 54 thereon which defines forwardly and rearwardly facing shoulders. When the insert is mounted in the upper shell portion 6, and the plug 2 is not mated with the receptacle 4, the forwardly facing shoulder provided by this collar bears against the rearwardly facing shoulder 26 on the interior surface of the shell as shown in FIG. 2. It will also be apparent from FIG. 2 that the intermediate section 46 of the insert is contoured to provide surfaces which bear against the portions 28, 30 of the internal surface of the shell while the right hand portion of the forward section 44 is of reduced cross-section and provides a rightwardly facing shoulder which is opposed to the leftwardly facing shoulder 37 on the internal surface of the shell.
A pair of springs 56 are mounted on the surface of the rearward insert section 48 between the rightwardly facing shoulder of the collar 54 and a clamping plate 64 described below. Each of these springs comprises a continuous formed section of beryllium copper strip or other suitable spring material, shaped to surround one-half of the insert section. The sides 60 of the springs converge towards each other and are joined by semicircular sections 58 on the upper and lower sides of the insert sections 48. Portions of the spring which bear against the oppositely directed sides of the insert section are inwardly formed as shown in section 62 to provide bearing areas 63 which bear against the shoulder of the collar 54 and the internal surface of the clamping plate 64. This clamping plate is secured to the rearward end of the shell section 6 by means of suitable fasteners as shown and has a central opening of a size such that the rearward end 48 of the insert assembly is permitted to project therethrough.
The insert assembly and springs are assembled to the shell section 6 by mounting the springs on the rearward portion of the insert assembly and forcing the forward portion 44 of the insert assembly beyond the constricted intermediate portion of the shell until the parts are in the position of FIG. 2. The retaining plate 64 is then secured to the rearward end of the shell section as shown.
The receptacle part 4 of the connector assembly is similar in many respects to the plug part and need not be described in complete detail. Accordingly, the structural features of the receptacle part 4 are identified by the same reference numerals, differentiated by prime marks, as are used in the foregoing description of the plug part. It will be noted that in many instances, the structural parts of the plug 4 are complimentary, rather than identical, to the corresponding parts of the receptacle; for example, the keying means in the receptacle parts comprises semicircular openings 14' adapted to receive the keys 14 and that the portion 34 of the opening in the upper shell portion 6 is adapted to receive the projecting end of the upper shell portion 6 of the plug. The contact terminals in'the receptacle comprises contact pins 52 which do not extend beyond the forward end of the connector part 4 so that they are always surrounded and protected in accordance with common practice in the connector art.
In the disclosed embodiment, the receptacle connector part is not provided with springs corresponding to the springs 56 of the plug part although the insert assembly in the receptacle part is structurally identical to the insert assembly 38 of the plug. Spacers 66 are, however, provided between the rearwardly facing shoulder defined by the collar 54' of the receptacle insert and the forwardly facing surface of the clamping plate 64 of the receptacle. These spacers effectively prevent any axial movement of the insert assembly 38 in the receptacle while such axial movement is permitted in the plug.
As previously noted, the forward sections 44, 44, of the insert assemblies 38, 38' are of a suitable rubber-like material such as a silicone rubber. It will also be noted that the mating face 42 of the insert assembly 38 of the plug projects slightly beyond the forward end 18 of the plug 2 when the parts are disengaged while the mating face 42' of the insert assembly 38' projects slightly beyond the shoulder 36 of the receptacle. When the parts are completely mated, these mating faces are compressed to the extent necessary to provide a sealed interface which moisture cannot readily penetrate and the possibility of flash-over between adjacent contact terminals will be minimized or eliminated. When the parts are mated as shown in FIGURE 3, the compressive stresses generated at the interface cause the insert assembly 38 of the plug to be displaced rightwardly as viewed in FIG. 3, by a slight amount with accompanying compression of the springs 56. By virtue of the compression of these springs, the insert assembly 38 in the plug is resiliently urged at all times toward insert assembly 38 in the receptacle.
A particular advantage of the disclosed embodiment of the invention is that the affects of Compression Set of the inserts at the mating face or interface are nullified and the interfacial seal will not be lost if such compression set takes place. Compression Set is generally considered to be the loss of elasticity in a rubber-like material which occurs when the material is subjected to a continuous compressive load and/ or to an elevated temperature. The degree of compression set in a given material is commonly determined by providing a disc of material oneinch in diameter and one-half inch thick, clamping this disc between two parallel plates, moving the plates towards each other until they are spaced apart by a distance of three-eighths inches, heating the clamped disc to a temperature of 257 F., and holding at that temperature for 24 hours. The specimen is then unloaded, allowed to cool to room temperature, and its thickness is measured. For most rubber-like materials, it will be found that the test specimen will not return to its original dimensions and will have a thickness somewhat less than the one-half-inch.
It will be apparent from the foregoing that if a connector depends entirely upon compression of the interface material for the interfacial sealing, compression set in the insert material at the interface will reduce the effectiveness of the interfacial seal and possibly cause failure. In accordance with the instant invention however, the effects of compression set in the inserts are counteracted by the compressed springs 56 which partially return to their relaxed positions in the event of compression set of the interface of the mated connector parts. It will be apparent that the hardness or resilience of the interface material and the stiffness of the springs 56 must be judiciously selected to achieve both compression of the interface material and partial loading of the springs 56 when the connector parts are mated with each other. It has been found from experience that the forward section of the insert assembly can advantageously be made of a silicone rubber having a durometer hardness of about A50 to achieve interfacial sealing of the connector. The characteristics of the springs 56 should then be selected to provide for retractile movement of the insert assembly 38 by an amount which is about twice the reduction in the length of the insert when the parts are mated. In other 'words, if the hardness of the portion 4-4 of the insert is A50, the characteristics of the springs 56 should be such that when the parts are mated the entire insert assembly will move rightwardly as viewed in FIGS. 2 and 3 against the biasing force of the springs by a distance which is twice the reduction in the length of the insert.
In the disclosed embodiment, the springs 56 are provided only in the plug portion of the connector assembly and are replaced by the spacer 66 in the receptacle which effectively prevents any axial movement of the inserts in that member. If desired, springs can be provided in the receptacle insert. It has been found, however, that springs need be provided in only one part of the connector to maintain the interfacial seal under all ordinary conditions.
The insert mounted in the lower shell portion 8 in FIG. 1 differs from the insert 38 in the upper shell portion in that the lower insert is provided with only two cavities 50a having coaxial contact terminals 52a mounted therein. The rearward section 48a of this insert assembly also may be of metal rather than of insulating material since the outer conductors of a coaxial contact terminal are usually grounded to the shell member. The instant invention has an added advantage for coaxial connectors in that the float or relative movement of the insert provided by the springs 56 function to maintain substantially complete engagement of the contact terminals of the plug with the terminals in the receptacle and further to maintain parallelism of the terminals in the plug with those in the receptacle, In the case of coaxial contact terminals, such complete engagement of the terminals is particularly important in order to maintain the electrical characteristics of the terminals when they are engaged with each other.
Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.
1. In an electrical connector assembly comprising a pair of matable connector parts, each part comprising an insert and a shell in surrounding relationship to said insert, said insert having a plurality of contact terminals therein and having a mating face and a rearward face, said mating faces of said inserts being in abutting relationship, and the contact terminals being engaged, when said parts are mated, the improvement to said connector assembly comprising:
a radially extending projection on said insert of one of said parts intermediate the ends thereof, said projection defining forwardly and rearwardly facing insert shoulder means.
forwardly and rearwardly facing shell shoulder means in said shell, said forwardly facing shell shoulder means being proximate to the rearward end of said shell and rearwardly facing shell shoulder means being intermediate the ends of said shell, said projection being between said shell shoulders, and
resilient means in surrounding relationship to said insert of said one part and interposed between said forwardly facing shell shoulder means and said rearwardly facing insert shoulder means and biasing said forwardly facing insert shoulder means against said rearwardly facing shell shoulder means,
said mating face of said insert projecting beyond said leading end of said shell when said forwardly facing insert shoulder means is against said rearwardly facing shell shoulder means whereby upon mating said parts, said insert means of both parts are moved against each other, and said insert means in said one part is moved relatively rearwardly in its shell with concomitant compression of said spring whereby said spring exerts a continuing force on said insert means in said one part urging said insert means in said one part towards said insert means in said other part.
References Cited UNITED STATES PATENTS 2,853,690 9/1958 Madison 339-45 3,404,365 10/1968 Obeissart 339- FOREIGN PATENTS 945,577 7/1956 Germany .5. 339-90 ERNEST R. PURSER, Primary Examiner J. H. MCGLYNN, Assistant Examiner