US3135571A - Connecting device - Google Patents

Description

June 2, 1964 K. KLINKwlTz coNNEc'rING DEVICE United States Patent O 3,135,571 CQNNECTING DEVICE Kurt Klinkwitz, Berlin-Lubars, Germany, assigner to Robert Bosch Elektronik G.m.b.ll., Berlin-Wilmersdorf, Germany Filed .idly Z2, 1963, Ser. No. 296,740

Claims priority, application Germany Aug. 11, i962 27 Claims. (Cl. 339-182) The present invention relates generally to the connector art, and, more particularly, to the construction of a coaxial plug for coaxial high frequency cables, and especially antenna cables, having a sleeve which surrounds the end of the cable, a plug prong in its front end electrically connected with the inner conductor of the coaxial cable, and the sleeve being electrically connected with the outer conductor of the cable by means of contacts disposed on the outer surface of the sleeve.

Coaxial plugs are used when it is desired to connect the conductors of a high frequency cable in a detachable manner to a receiving device, such as, for example, radio or television apparatus. usually does not have any resilient elements and can be connected to the inner conductor of the cable without difficulty because the plug prong and the inner conductor are disposed centrally of the other elements and/or coaxially, substantial difficulties arise in the attempt to provide a satisfactory and flawless electrical connection between the contacts positioned on the outer surface of the sleeve and the outer conductor of the cable. For example, the outer conductor is provided in the form of a shielding mesh disposed around the insulation of the inner conductor and most of the time is insulated by means of an outer shell or sheath. Special considerations are required if, in addition, there is a necessity for fashioning the contacts on the outer surface of the sleeve to be resilient for purposes of contact safety and to obtain as small a physical dimension of the plug as is possible.

Coaxial plugs are already known which have a metal sleeve whose rearward end presses upon the outer conductor and establishes contact therewith. The front end f the sleeve carries an insulating ring for mounting the plug prong. With this construction there is the disadvantage that the insulating distance between the sleeve and the prong of the plug is relatively small since the circumference of the insulating ring is surrounded or enclosed by the sleeve. Furthermore, the sleeve sits upon the outer conductor only by means of pressure and does not provide a safe contact between the outer conductor and the sleeve since the outer conductor is only disposed upon the relatively resilient insulation of the inner conductor.

ln another plug which is known the electrical contact between the outer conductor and the metal sleeve is provided by inserting hairpin-like contact springs having one leg disposed between the outer conductor and the insulating outer shell and with the other leg between the outer surface of the outer shell and the inner surface of the sleeve. However this construction also does not provide for the safe and proper making of contact since the insulation of the inner conductor disposed beneath the outer conductor yields and thus a firm contact is not provided.

ln order to obtain a faultless and proper contact at the other contact point which is involved only after the coaxial plug has been inserted into the correspondingly shaped socket provided at the receiver and which contact point is disposed between the sleeve and the inner wall of the socket, a partially ring-shaped contact spring is provided in the front portion of the above-described known plug and is positioned in an axially parallel manner and is disposed against the inner wall of the metal sleeve.

While the plug prong The ends of this spring are bent radially outwardly and project through longitudinal slits in the sleeve so as to extend externally thereof and provide a resilient contact with the socket of the receiving device. However, the manufacture of this partially ring-shaped contact spring is very expensive because the manufacturing tolerances must be maintained within very small limits.

Another known type of plug is constructed according to German Gebrauchsmuster No. 1,837,970. In this construction, a sleeve molded from plastic material surrounds the end of a coaxial cable. The prong of the plug which is connected with the inner conductor passes through the forward end of the sleeve and two resilient sheet metal strips are provided on the outer surface of the sleeve. The ends of these metal strips are bent at right angles and inwardly toward the cable and are pressed into the cable shell by means of a pressure ring. These ends of the sheet metal strips are formed as teeth on the front faces thereof and these teeth puncture the shell of the cable and establish contact with the outer conductor which is provided immediately beneath the shell. However, the Contact between the sheet metal strips and the outer conductor is not reliable because, in order to avoid damaging the outer conductor the contact pressure may only be very small and because the counter pressure is only provided by the Very resilient insulation between the outer conductor and the inner conductor. The two resilient sheet metal strips engage each other at their forward ends and the plug prong passes therethrough and is spaced at a small distance therefrom. The insulating distance between theplug prong and the two resilient sheet metal strips can only be maintained to be suiciently great at the cost of the over-all structural length of the plug.

With these defects of the prior art in mind, it is a main object of the present invention to provide a plug construction for coaxial cables which assures the making of a secure contact at the outer conductor.

Another object of the invention is to provide a plug of the character described wherein the insulating distance at the point that the plug prong penetrates through the plug is suiciently large so as to avoid the defects of the prior art.

A further object of the present invention is to provide a plug construction which accomplishes the above-mentioned objects and at low manufacturing costs.

Still another object of the invention is to provide a plug construction for coaxial cables wherein the contacts for the outer conductor may be securely connected to the outer conductor and pass through the plug body outwardly thereof.

These objects and'others ancillary thereto are accomplished in accordance with preferred embodiments of the invention wherein a sleeve forming the plug body is a plastic body which is extruded or molded directly about the end of the cable and the plug prong. Contacts are connected with the outer conductor and they are in the form of leaf springs which are soldered to the outer conductor, penetrate outwardly through the plastic body, and are bent backwardly toward the outer surface of the plastic body.

The above-mentioned known plugs and others are constructed in such a manner that a connection can not be provided by soldering the outer conductor and a sleeve of metal and/or the contacts provided on the outer surface of a sleeve molded from plastic. In accordance with the present invention the contacts are arranged in the form of leaf springs and are directly soldered onto the outer conductor and pass through the plastic body exteriorly thereof. Furthermore, because the location of the leaf spring penetration through the plastic body is disposed at an appreciable distance from the location where the plug prong passes outwardly of the plastic body, the insulating distance between the plug prong and the leaf springs is sufliciently long, and the plug can be manufactured in a simple manner.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE l is a sectional View, partly in elevation, of a straight coaxial plug in accordance with the present invention.

FIGURE 2 is an elevational view of an angle plug.

FIGURE 3 is a sectional view, partly in elevation, of another form of angle plug.

In accordance with the present invention a particularly secure connection of the leaf-spring-type contacts with the outer conductor is provided by soldering the leaf springs to the outer conductor. This is accomplished by forming the leaf springs as projections or extensions on a cylindrical ring which surrounds the outer conductor. If the outer conductor is, for example, a shielding mesh, then a ring may be slipped over the mesh and can be soldered thereto in a simple and trouble-free manner. The leaf springs may project from the front surface of the cylindrical ring, considered in the direction of the axis of the ring, and they are bent to extend radially away from the ring. These leaf springs penetrate the plastic body in the direction in which they project and finally, those portions thereof which project out of the plastic body are bent backwards toward the outer surface of this plastic body. Mechanical stresses on the portions of the leaf springs which project out of the plastic body can not be transferred or transmitted to the soldered joint because the leaf springs are fixedly embedded in the plastic body. In a suitable manner, the plug prong may be anchored in the plastic body by providing a collar at the rearward end of the plug prong and the plastic. body extends around this collar.

According to a further feature of the invention an insert may be provided in the cable, at least in the region of the plastic body and this insert may, for example, be a Wire or band-shaped element which provides rigidity. The insert is used in order to prevent the high-frequency cable, which usually is flexible, from assuming an undesirable position during the extruding process and/or during the molding process wherein the outer conductor may be positioned too close to the outer surface of the extruded plastic body. This is simpler than the construction which is provided in a known plug wherein supporting elements, together with supporting rings spaced at a distance from one another, are provided which maintain the cable in a central position and which are sprayed with plastic or molded together with the cable.

Preferably, in the event that low-loss coaxial high frequency cables are used wherein the inner conductor is mounted within a hollow tube and has a substantially larger free cross section than the cross section of the inner conductor, an insert for providing rigidity may be inserted in the hollow tube surrounding the inner conductor. In accordance with further features of the invention this stiffening or rigidifying insert may extend beyond the rearward end of the plastic body and either over its entire length or at certain sections along its length it may be permanently flexible, and, for example, may be angularly bent at right angles at a point behind the plastic body.

The plug may be thus produced in its nished form with an insert which is disposed axially of the plug and subsequently, if necessary, the portion of the cable which projects from the rearward end of the plastic body may be bent into any direction as is desired or necessary under the exigencies of the situation. Also, the plug may be used without angularly bending the cable at all, for example, in order to be able to handle the plug more conveniently.

A corresponding strong copper wire has proven to be advantageous as an insert, and such a wire may be more fiexible in the longitudinal portion thereof which extends beyond the rearward end of the plastic body than in the region of the plastic body. This may be provided, such as, by not annealing the wire in the region of the plastic body.

The construction of a plug in accordance with the present invention provides a substantial decrease in expense in comparison with the previously known plugs and assures a secure contact at the outer conductor even if the construction providing the possibility for bending of the cable into the desired position when needed is not used, but rather if coaxial plugs having an axially bent cable, which are called angle plugs, are delivered directly from the plant. Furthermore, an angle plug which is constructed in accordance with the present invention has substantially smaller dimensions than those angle plugs which have been known heretofore and they generally satisfy the requirements for such angle plugs.

Furthermore, for sturdier consultations of such angle plugs the stifening insert and the plastic body may have an angular, for example, a right-angle bend. The stiifening or reinforcing insert also extends in the region of the plastic body and has a corresponding bend so that the correct position of the cable within the body is guaranteed even after the molding process. The reinforcing insert does not extend beyond the rearward end of the plastic body. The plastic body extends over the length of the bend and provides a sturdier construction to the plug than that of the above-mentioned angle plug in which the plastic body extends only over the forward straight portion of the insert.

In accordance with another feature of the present invention, the plug prong may be hollow and the rigidifying insert may extend into the hollow chamber of the plug prong and if desired may be soldered to the plug prong. Because of this construction the plug prong is provided with a particularly secure mounting in the plastic body since the reinforcing insert primarily extends within the cable and this cable in turn is lixedly embedded in the plastic body.

In order to provide contact between the inner conductor of the cable and the plug prong, the inner conductor extends into the hollow cavity of the plug prong and is soldered to the prong. The soldering operation is shortened and simplified if the rigidifying insert as well as the inner conductor extend up to the forward end of the hollow plug prong and if the plug prong, the insert and the inner conductor are soldered together with a single soldering operation.

Another arrangement for the electrical connection between the inner conductor and the plug prong is provided by soldering the inner conductor to the stiifening insert close to the rearward portion of the insert. The front end of the rigidifying insert is then soldered to the front end of the hollow plug prong.

In accordance with a further feature of the invention a plug may be constructed by soldering onto the outer conductor of a cable a generally cylindrical ring having radially outwardly extending leaf springs. The leaf springs are disposed substantially at right angles to the central axis of the ring and a plug prong is electrically connected to an inner conductor, for example, by soldering. The pastic body is provided about the cable using a die mold and the plastic body encloses the end of the cable together with the ring and the end of the plug prong. Portions of the leaf springs project outwardly of the plastic body and are bent backwardly toward the outer surface of this plastic body. After the plastic body has been produced, the leaf springs may be bent backwardly toward the outer surface of the plastic body in such a manner that they lie on the outer surface of the body in a somewhat arched fashion, approximately like the leaf springs of a banana plug and by this means the making of proper contact is particularly assured. The

extrusion and/ or molding die may be constructed so that the greater part of the length of the plug prong, the leaf springs extending at right angles to the central axis of the ring, and the rearwardly extending cable can be accommodated by the walls of the die. If a stronger cable is to be provided with a plug, the cable, only to a minor degree, will be capable of being pushed away from its original position during extruding, particularly since it is securely centered at its front end by means of the leaf springs.

However, in most cases, such as for example, in the case of an antenna cable used for a vehicle antenna or for television apparatus, a relatively thin and exible cable is provided with a plug. In order to assure that such a cable maintains its position during the molding process a suitable stitfening insert may be mounted within the cable and soldered together with the inner conductor as well as with the plug prong.

ln order to provide the electrical connection between the inner conductor and the plug prong the inner conductor is arranged to at first project outwardly of the front end of the cable. The inner conductor is then soldered near the rearward end of the stiffening insert and the hollow plug prong is placed onto the front end of the insert and is soldered to the insert. The insert is pushed so far into the hollow tube which surrotmds the inner conductor that the rearward end of the plug prong touches or abuts against the front end of the cable. The ring is then soldered onto the outer conductor and the plastic body molded onto the end of the cable and about the ring with the leaf springs extending outwardly therefrom. Finally, the leaf springs are bent rearwardly toward the outer surface of the plastic body.

According to a further feature of the present invention the electrical connection between the inner conductor and the plug prong can also be provided by placing the hollow plug prong over the front of the stiffening insert and over the inner conductor and by soldering the insert as well as the inner conductor to the front end of the plug prong.

By means of the above-described methods, straight plugs can be made when the cable exits from the rearward end of the plastic body in a straight line along the center longitudinal axis of the plugs. In many cases it is desirable that the cable exit from the plug at a particular angle and preferably at a right angle. In order to provide such an angle plug the stitfening insert may be made of permanently exible material which is considerably longer than the distance from the front end of the plug prong to the rearward end of the plastic body. After the electrical connection has been made between the inner conductor and the plug prong, the insert is placed into the cable far enough so that it projects an appreciable distance beyond the end of the plastic body. After the plastic body has been molded to the end of the cable, the portion of the cable projecting from the rearward end of the plastic body is bent to the desired angle immediately behind the plastic body.

According to a further feature of the invention a sturdier angle plug can be made by placing the insert in the cable while it is straight. Then, the insert is bent angularly together with the cable and the plastic body is formed in a die mold with the correspondingly bent central or longitudinal axis.

With more particular reference to the drawings, FIG- URE l illustrates one embodiment of a coaxial plug in accordance with the present invention. A coaxial cable i arranged to carry high frequencies has an inner conductor 3 which extends in an undulating manner within an insulating hollow tube 2. An outer conductor 3 is provided in the form of a shielding mesh, and an insulating outer shell 4 is provided over this mesh. A stiifening or reinforcing insert 9 of conductive material is inserted into the end of the cable. The left end of the insert 9 is electrically connected with the hollow plug prong 7 by means of a soldered connection 25. At its right end 6 the insert is electrically connected with the inner conductor 8 also by means of a soldered connection 1S.

A cylindrical ring 6 is soldered onto the shielding mesh 3. The ring has two projections which originally are disposed at right angles to the central axis of the ring as illustrated in dashed lines. These projections are constructed in the form of leaf springs 5.

A plastic body 1Q is directly molded around the cable 1 and the plug prong 7. This plastic body xedly and immovably mounts the plug prong '7 to the cable by means of a collar lr6 provided thereon as well as the two leaf springs 5 which are then bent back against the outer side of the plastic body 10 as illustrated in solid lines in FIG- URE l.

With more particular reference now to FIGURE 2, a modification of the present invention is illustrated wherein a cable 22 at first has a straight end as indicated by the dashed lines. A straight insert 12 is provided in the cable and the insert together with the inner conductor 1'7 is provided within a hollow tube 21 of the cable 22. The insert and the inner conductor are soldered to the left end of a hollow plug prong 7 by means of a conventional soldering joint 11. A plastic body 13 is molded about the straight insert 12. The cable 22 projects out of the body in the direction shown in dashed lines and toward the right so that a straight plug is formed. The leaf springs 5 are placed into the position illustrated in the drawing. After the cable has been bent angularly directly behind the plastic body, the straight insert 12 becomes an insert which is angled downwardly as shown at 19 and a bent cable 26 is thus formed. Thus, the plug which is shown in solid lines in FIGURE 2 is an angle plug which has been bent into this form from a straight plug.

With more particular reference to FIGURE 3, a further embodiment of the present invention is illustrated. A cable 23 is provided with an insert 14 which is initially straight and which is soldered to the left end of a plug prong 7 together with the forward end or leading end of an inner conductor 2t) by means of a soldered joint 24. The cable is then bent at a right angle downwardly together with its insert and while bent it is placed into a die mold having a central axis which runs to be coincident with the bend and a plastic body 15 is thus molded. The leaf springs 5 which initially project from the plastic body at right angles thereto are then bent into the form as illustrated in the drawing.

It will be understood that the above description of the `present invention is susceptible to various modifications,

changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A coaxial plug for coaxial cables having inner and outer conductors, said plug comprising, in combination: a plug prong electrically connected with the inner conductor of a cable; a one-piece sleeve-like plastic body directly surrounding the end of such cable and a portion of the plug prong for supporting the prong; and contacts in the form of leaf springs in electrical contact with the outer conductor of such cable, said leaf springs penetrating externally of said plastic body and being bent backwardly toward the outer surface of said body.

2. In a coaxial plug for coaxial high frequency cables, and especially antenna cables, having a sleeve enclosing the end of the cable and at its front end carrying a plug prong electrically connected with the inner conductor of the cable, the sleeve having contacts on its outer surface which are electrically connected with the outer conductor of the cable, the improvement wherein the sleeve is a plastic body molded directly around the cable and the plug prong, the contacts connected with the outer conductor are leaf springs soldered to the outer conductor, said leaf springs penetrating the plastic body and being bent backwardly toward the outer surface of the body.

3. The improvement as defined in claim 2 comprising a ring surrounding the outer conductor, and said leaf springs being defined by projections on said ring. a

4. The improvement as defined in claim 2 wherein said plug prong has a collar in proximity to its rearward end, and said plastic body extending around and holding said collar.

5. The improvement as defined in claim 2 comprising a stiffening insert in the cable at least in the region of said plastic body.

6. The improvement as defined in claim 5 wherein said insert extends beyond the rearward end of said body.

7. The improvement as defined in claim 5 wherein said insert is permanently fiexible at least along portions of its length.

8. The improvement as defined in claim 5 wherein said insert is bent angularly behind said plastic body.

9. The improvement as defined in claim 8 wherein the insert is bent substantially at a right angle.

10. The improvement as defined in claim 5 wherein both said insert and said body are bent angularly.

11. The improvement as defined in claim 10 wherein said insert and body are bent at substantially a right angle.

12. The improvement as defined in claim 5 wherein the plug prong is hollow and the insert extends into the interior of the prong.

13. The improvement as defined in claim 12 wherein the insert is soldered to the prong.

14. The improvement as dened in claim 13 wherein the inner conductor is disposed within the prong and is soldered to the prong.

15. The improvement as defined in claim 13 wherein the inner conductor is soldered to the insert.

16. The improvement as defined in claim 15 wherein the inner conductor is soldered to the insert in proximity to the rearward end of the insert.

17. A method for making coaxial plugs for coaxial cables including an inner conductor, an insulating hollow tube, and an outer conductor, comprising the steps of: soldering onto the outer conductor of a cable a ring having leaf springs disposed substantially at right angles to the central axis of the ring; electrically connecting a plug prong with the inner conductor of such cable; molding in a die mold a plastic body to enclose the end of the cable, a portion of the plug prong, and the ring so that the leaf springs project therefrom; and bending the projecting portions of the leaf springs backwardly toward the outer surface of the plastic body.

18. A method as defined in claim 17 wherein the electrically connecting step is accomplished by soldering.

19. A method as defined in claim 17 comprising placing a stiffening insert into the cable and soldering it with the inner conductor and with the plug prong to accomplish the electrically connecting step.

20. A method as defined in claim 17 wherein the step of electrically connecting the prong and the inner conductor includes removing portions of the hollow tube and the outer conductor so that the inner conductor projects from the forward end of the cable, soldering the projecting inner conductor to a stiffening insert in proximity to its rearward end, placing the plug prong which is hollow onto the front end of the insert and soldering it thereto, and pushing the insert into the hollow tube until the rearward end of the plug prong abuts against the front end of the cable.

21. A method as defined in claim 17 wherein the step i 0f electrically connecting the prong and the inner conductor includes pushing a stiffening insert into the hollow tube, placing the plug prong which is hollow over the insert `and the inner conductor, and soldering the insert and the inner conductor to the front end of the plug prong.

22. A method for making coaxial plugs for coaxial cables including an inner conductor, an insulating hollow tube, and an outer conductor, comprising the steps of: placing into the cable a stiffening insert of permanently flexible material and which is a considerable distance longer lthan the distance from the front end of the prong to the intended rearward end of the plug until it projects a considerable distance beyond the point where the rearward end Iof the plug is to be located; soldering onto the outer conductor of a cable a ring having leaf springs disposed substantially at right angles to the central axis of the ring; electrically connecting the plug prong with the inner conductor of such cable; molding a plastic body to enclose the end of the cable, a portion of the plug prong, and the ring so that the leaft springs project therefrom; bending the projecting portions of the leaf springs backwardly toward the outer surface of the plastic body; and bending the cable immediately behind the plastic body so it is disposed angularly with respect to the body.

23. A method as defined in claim 22 wherein the step of electrically connecting the plug with the inner conductor includes soldering the inner conductor to the rearward end of the insert, and soldering the front end of the insert to the plug prong.

24. A method as defined in claim 22 wherein the step of electrically connecting the plug with the inner conductor includes soldering both the inner conductor and the insert to the plug prong.

25. A method for making coaxial plugs for coaxial cables including an inner conductor, an insulating hollow tube, and an outer conductor, comprising the steps of: placing a straight stiiiening insert into the cable; soldering onto the outer conductor of a cable a ring having leaf springs disposed substantially at right angles to the central axis of the ring; electically connecting a plug prong with the inner conductor of such cable; bending the cable and the insert to substantially form a right angle; molding a plastic body to enclose the end of the cable, a portion of the plug prong, and the ring so that the leaf springs project therefrom and the body forms a right angle; and bending the projecting portions of the leaf springs backwardly toward the outer surface of the plastic body.

26. A method as defined in claim 25 wherein the step of electrically connecting the plug with the inner conductor includes soldering the inner conductor to the rearward end of the insert, and soldering the front end of the insert to the plug prong.

27. A method as defined in claim 25 wherein the step of electrically connecting the plug with the inner conductor includes soldering both the inner conductor and the insert to the plug prong.

References Cited in the file of this patent UNITED STATES PATENTS 1,175,343 Conard Mar. 14, 1916 3,001,169 Blonder Sept. 19, 1961 FOREIGN PATENTS 531,947 Great Britain Ian. 14, 1941 677,580 Great Britain Aug. 20, 1952

Claims (1)

1. A COAXIAL PLUG FOR COAXIAL CABLES HAVING INNER AND OUTER CONDUCTORS, SAID PLUG COMPRISING, IN COMBINATION: A PLUG PRONG ELECTRICALLY CONNECTED WITH THE INNER CONDUCTOR OF A CABLE; A ONE-PIECE SLEEVE-LIKE PLASTIC BODY DIRECTLY SURROUNDING THE END OF SUCH CABLE AND A PORTION OF THE PLUG PRONG FOR SUPPORTING THE PRONG; AND CONTACTS IN THE FORM OF LEAF SPRINGS IN ELECTRICAL CONTACT WITH THE OUTER CONDUCTOR OF SUCH CABLE, SAID LEAF SPRINGS PENETRATING EXTERNALLY OF SAID PLASTIC BODY AND BEING BENT BACKWARDLY TOWARD THE OUTER SURFACE OF SAID BODY.

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