Three-piece Coaxial Cable Connector

Abstract

A three-piece connector is provided which may be securely attached both mechanically and electrically to a coaxial cable without requiring the removal of the cables outer cover. The connector includes a connector body having a longitudinal bore formed therein, an axially-movable cam sleeve adapted to slide within the longitudinal bore, the sleeve having a camming surface formed on one end thereof, and a serrated crimping washer having inwardly directed crimping teeth in engagement with the camming surface. The end of a coaxial cable with its center conductor exposed is pulled through the longitudinal bore and its center conductor is inserted into a lock nut. The connector body is then screwed onto the lock nut with the forward end thereof actuating the cam sleeve within the longitudinal bore, driving the crimping teeth inwardly to penetrate the cables outer sheath and into engagement with the outer conductor of the coaxial cable to effect a positive ground connection and to lock the coaxial cable within the connector.

Description

The present invention relates generally to electrical connectors and, more particularly, to an improved connector for a coaxial cable. Advantageously, the connector and coaxial cable are assembled by a simple threading operation.

Those concerned with the development of electrical connectors have long recognized the need for a simple and efficient coupling device for coaxial cables. The type of coaxial cable normally employed includes an inner center conductor surrounded by a thickness of high insulation material, which in turn is surrounded by an outer conductor which may be of the braided or foil type, the entire structure having an outer cover of insulation material. There have been many types of connectors made for connecting such coaxial cables to an instrument chassis, another line or a similar cable. Most such connectors include four or more parts and are relatively complex and expensive to manufacture. One such prior art embodiment utilizes a sleeve having projections formed thereon which are driven or compressed into the outer conductor of the coaxial cable by a camming operation effected by the threading together of a nut and compression member. However, such devices have not been completely satisfactory. The strength of the grip afforded by such a structure, with respect to an axial force applied to the cable, has been found to be insufficient. More particularly, when the cable is under tension, the projections which have been driven into the outer conductor of the cable will tend to tear the outer conductor, resulting in a weak mechanical grip and a poor electrical contact.

Another significant disadvantage with prior art connectors is that a great deal of prepartion of the coaxial cable is necessary before it may be inserted within the connector body. In addition to exposing the center conductor of the coaxial cable for a short distance, most prior art connectors require that the outer jacket or insulation be removed beyond that distance to expose the outer conductor before good electrical contact can be achieved. Thus, the prior art does not provide a simple and efficient coupling device for coaxial cables.

It is an overall object of this invention to provide a simple electrical connector having an improved mechanical and electrical connection to coaxial cables and, more particularly, a connector which provides a strong grip on the cable and a positive electrical connection thereto, yet requires only minimal cable preparation.

Briefly, in accordance with the principles of the invention, a simple three-piece connector is provided which includes an anti-pullout device that provides both mechanical and electrical contact to coaxial cables. The three-piece connector includes a connector body having a longitudinal bore formed therein, an axially movable cam sleeve adapted to slide within the longitudinal bore and having a camming surface formed on one end thereof, and a serrated crimping washer having inwardly directed crimping teeth in engagement with the camming surface. The exposed end of a coaxial cable is pulled through the longitudinal bore and its center conductor is inserted into a lock nut. The connector body is then screwed onto the lock nut and the forward end thereof actuates the cam sleeve to slide within the longitudinal bore. The camming surface of the sleeve biases the crimping teeth further inwardly through the cables outer sheath and into engagement with the outer conductor to effect a positive ground connection and to lock the cable within the connector. Accordingly, the connector of the present invention eliminates the need for removing the outer sheath beyond the exposed inner conductor, since the crimping teeth penetrate the outer sheath simplifying preparation of the coaxial cable. Once the crimping teeth have penetrated the outer sheath and have gripped the coaxial cable within the body of the connector, any axial force or tension placed on the cable tending to remove it from the connector body only tightens the grip of the serrated crimping washer. In addition, as the crimping teeth are gripping the outer sheath in addition to the outer conductor, tension on the cable will not damage or tear the outer conductor.

Further objects, features and advantages of the present invention will become apparent upon the consideration of the following detailed description of a presently preferred embodiment when taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a side view, with parts in section, of the connector of the present invention before it has been coupled to a coaxial cable;

FIG. 2 shows the connector and coaxial cable after it has been inserted through the connector body and into the lock nut, but before the lock nut has been threaded into the connector body; and

FIG. 3 shows the connector after the lock nut has been threaded therein to drive the crimping teeth inwardly to grip the coaxial cable.

Referring now to FIG. 1, there is shown the novel three-piece connector 10 of the present invention ready to receive a coaxial cable 26. In the preferred embodiment, the connector 10 comprises a housing or connector body 12, an axially-movable cam sleeve 14 and a serrated crimping washer 16. The connector body 12 is provided with a longitudinal bore for receiving therethrough coaxial cable 26. An internal shoulder 12a is formed on the interior surface of the longitudinal bore and prevents the removal of cam sleeve 14 after it has been assembled within connector 10. One end of connector body 12 is provided with an internal threaded surface 12b which extends along a portion of the longitudinal bore and up to internal shoulder 12a.

Axially-movable cam sleeve 14 is concentrically mounted within the longitudinal bore of connector body 12 and is adapted to slide therein upon actuation by a lock nut 20, to be explained. The inner bore of cam sleeve 14 is just large enough to allow cable 26 to slide through and engage lock nut 20. The outer surface of cam sleeve 14 is provided with an annular abutment 14a which engages internal shoulder 12a. Cam sleeve 14 is further provided with a camming surface 14b formed on the interior surface of cam sleeve 14 and at one end thereof. Camming surface 14b is arranged to overlay a portion of crimping washer 16 for a purpose to be explained.

Serrated crimping washer 16 is mounted within the longitudinal bore of connector body 12 and is adapted to slide therein upon actuation by cam sleeve 14. Serrated crimping washer 16 is provided with an opening 16a through which cable 26 may slide when it is to be assembled with connector 10. Crimping washer 16 is also provided with a plurality of equally spaced, sharp-pointed crimping teeth 16b which are flared or biased in an inward direction. Crimping teeth 16b are inwardly flared as shown so that upon actuation by camming surface 14b, the ends of crimping teeth 16b will move further inwardly to penetrate the outer sheath of coaxial cable 26 and contact outer conductor 26c.

In order to actuate cam sleeve 14 and crimping washer 16, a lock nut 20 is provided. Lock nut 20 is externally threaded at one end thereof, as shown at 20a, and is threadedly engageable in the threaded portion 12b of connector body 12.

The method of assembling the three-piece connector 10, coaxial cable 26 and lock nut 20 will now be explained, with particular reference being made to FIGS. 2 and 3. Coaxial cable 26 includes an inner center conductor 26a of wire surrounded by a thickness of high insulation material 26b, which in turn is surrounded by a braided outer conductor 26c, the entire structure having an insulation material 26d. As may be seen in FIG. 2, lock nut 20 is provided with an inner bore to receive the center conductor 26a of coaxial cable 26 after cable 26 has been drawn through the longitudinal bore of connector 10. Upon insertion of the center conductor 26a into the bore of lock nut 20, the coaxial cable 26 engages a forward edge 28 of lock nut 20 in order to properly locate cable 26 with respect to lock nut 20. As coaxial cable 26 is drawn through the longitudinal bore of connector 10, abutment 14a formed on cam sleeve 14 will engage internal shoulder 12a and thereby prevent the coaxial cable 26 from pulling cam sleeve 14 out of the longitudinal bore of connector 10.

After center conductor 26a has been inserted within the bore of lock nut 20, lock nut 20 is then threaded into the connector body 10. As the lock nut 20 is screwed into the connector body 12, the forward or leading end 28 of lock nut 20 presses against one end of cam sleeve 14, as shown in FIG. 3. As the lock nut 20 is threaded further into connector body 12, the camming surface 14b of cam sleeve 14 will apply pressure to the inwardly flared, sharp-pointed teeth 16a of crimping washer 16. As a result, camming surface 14b biases crimping teeth 16a further inwardly, through the jacket 26d of coaxial cable 26 to contact outer conductor 26c. In this manner, a positive ground connection is provided and coaxial cable 26 is locked within the connector body 12.

It should be clear that means other than lock nut 20 may be employed to actuate cam sleeve 14 within the longitudinal bore of connector 10. For example, a tool may be inserted within the longitudinal bore of connector 10 to actuate cam sleeve 14 to drive crimping teeth 16a through the jacket 26d of coaxial cable 26.

From the foregoing, it will be appreciated that there has been provided in accordance with the present invention, a simple and efficient three-piece connector for a coaxial cable wherein preparation of the cable is greatly simplified as the need for removal of the outer sheath beyond the exposed inner conductor has been eliminated. Moreover, the novel connector provides an improved gripping or anti-pullout device which only tends to increase the strength of the connector grip when the coaxial cable is under tension with respect to the connector.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances, some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

Claims

What is claimed is:

1. An electrical connector for a coaxial cable which includes an axial inner conductor, an inner dielectric surrounding said inner conductor, an outer conductor and an outer dielectric surrounding said outer conductor, said connector comprising a connector body having a longitudinal bore formed therein for receiving one end of said coaxial cable, an axially movable cam sleeve mounted within the longitudinal bore of said connector body and adapted to slide therein, said cam sleeve having a camming surface formed on the interior surface of said sleeve, crimping means having a plurality of crimping teeth which are inwardly curved mounted within the longitudinal bore of said connector body and adapted to slide therein, said camming surface being in direct engagement with and overlying said crimping teeth, means for actuating the camming surface of said cam sleeve to engage and bend said crimping teeth inwardly to penetrate the outer dielectric to contact the outer conductor of the coaxial cable.

2. An electrical connector in accordance with claim 1 wherein said actuating means includes a lock nut adapted to be received by one end of said connector body, the forward end of said lock nut engaging one end of said cam sleeve upon actuation.

3. An electrical connector in accordance with claim 1 wherein said connector body has an internal shoulder formed thereon to engage and prevent said cam sleeve from being removed from said connector body.