US3436105A - Connector - Google Patents

Description

April 1969 J. MlKLYA 3,436,105

CONNECTOR Filed 00?. 22, 1965 I NVENTOR. JOHN M/Kz. YA BY Armwwr United States Patent 3,436,105 CONNECTOR John Miklya, 529 11th Ave. N., South St. Paul., Minn. 55075 Filed Oct. 22, 1965, Ser. No. 501,929 Int. Cl. F161 39/00 US. Cl. 285321 2 Claims ABSTRACT OF THE DISCLOSURE A versatile connector for attachment to members of generally circular cross-section, especially electrical conduit or cable. The connector has a socket for receiving the circular member, the socket being provided with a plurality of aligned equidistantly spaced circumferential apertures in the wall, into which fits a spring member having radially inwardly urged protrusions mating with and extending through the apertures. The protrusions have gripping contact points, such as teeth which are oriented away from the open end of the socket. The teeth will slide with respect to the circular member when inserted into the socket, but normally will engage the surface of the member when an attempt is made to withdraw it from the socket. The ends of the spring member are spreadable, so as to permit lifting of the protrusions freeing the circular member for removal.

The present invention relates generally to electrical connectors, and particularly to connectors by which fiexible conduit is attached to electrical connection boxes.

For many years flexible electrical conduit (often known under the generic designation of Greenfield) and armored cable (known as BX cable) have been fastened to electrical boxes by means of a connector having a cylindrical socket on one end and a threaded bushing on the opposite end. The size of the threaded bushing is such as to fit within the knock outs in the outlet box, to be held in place by a threaded nut turned onto the bushing from within the box. conventionally a flange is provided to serve as a stop or shoulder which bears against the outer wall of the box, the threaded nut being tightened up against the inner wall of the box, rigidly to hold the connector in place.

The socket end of the connector is coventionally provided with a set screw. It is of a size such that Greenfield cable of conventional sizes will just fit within the socket, the set screw being tightened down upon the cable to hold it in place. Thus, is the manner in which Greenfield cable is conventionally connected to the outlet box.

As a practical matter in connecting up electrical installations, the set screw in the socket must be loosened before the Greenfield can be inserted. Often in haste the electrician inadvertently turns the set screw completely out of the socket and loses it on the floor. It is usually inconvenient or awkward to step down from a ladder in order to retrieve the set screw, and the electrician often will then discard the connector, it being less inconvenient to throw it away than to search for and retrieve the lost set screw. Needless to say, this is a wasteful practice.

The present invention is concerned with the provision of a connector in which cable can readily be inserted and held, without the need of loosening or tightening set screws, and which also can be very simply removed from the cable, should it be desired to remove or disconnect it. The nature of my invention will be apparent from the description which follows, taken in conjunction with the appended drawing, in which like reference characters refer to corresponding parts in the several views, and in which:

FIGURE 1 is a side view of my device, partially broken 3,436,105 Patented Apr. 1, 1969 away, showing Greenfield cable inserted therewithin; and

FIGURE 2 is a section view taken along the lines of 22 of FIGURE 1.

Referring now to the drawing, my novel connector 10 is formed geerally of a socket 12, a shoulder flange 14, and a threaded end or bushing 16. The shoulder and bushmg combine to provide means by which the connector is attached to an electrical box, similarly as in prior art devices; a nut (not shown) being turned onto the bushing from within the box to hold it tightly against the shoulder.

The socket 10 is generally cylindrical in shape, of inside diameter to readily but not too loosely receive cable or conduit, such as Greenfield cable. Approximately mid-way along its length the socket 12 is provided with three equidistantly spaced circumferential slots 18 in the wall thereof.

A spring 20, extending about the socket 12, is provided with three inward protrusions 22, which respectively extend into and protrude through the wall of the socket. As shown in FIGURE 2, the bases of the spring protrusions 22 are nearly, but not quite, as long as the circumferential slots 18, and preferably are slightly arcuate in shape, as shown (so as collectively to define a crrcular arc concentric with, but within, the socket wall).

The edges of the protrusion bases away from the end opening 26 of the sockets are provided with teeth 28, which extend radially inwardly and away from the socket opening.

The length of spring 20, in relation to the size of the exterior of socket 12, is such that a slight gap is left be tween the spring ends 30 and 32. It will be seen that by using a screw driver or other prying tool, the said ends can be forced apart to lift the protrusions 22 from their position within slots 18.

In use, the end 34 of a length of conduit or cable is simply inserted within socket 12. This is easily accomplished since the spring protrusions 22 and teeth 28 do not grip the cable when the motion is in this direction. Rather, they lift slightly, as necessary to accommodate the cable. However, when an attempt is made to withdraw the cable from the socket, the protrusion and teeth catch the cable and bite into it, preventing it from being pulled free.

Thus, quick secure connections to the cable can be made with my device.

Should it be desired to remove the cable, a screw driver is used to pry apart spring ends 30 and 32, and the spring protrusions are thereby lifted and freed from their grip ping contact with the cable, allowing it to be readily pulled out of the socket.

While my device, as described, contains three slots in the socket wall, and three mating protrusions in the spring, this number is not essential. Other equivalent structures are contemplated, it being understood that the description is for the purpose of illustrating my invention, not to limit it.

What I claim is:

1. In a connector adapted for attachment to a member of generally circular cross-section and a generally uniform outer surface, a socket having an open end for receiving such member, said socket having an inside diameter slightly larger than the outside diameter of said member, a plurality of aligned equidistantly spaced circumferential apertures in the wall of said socket, a spreadable spring member extending about said socket having radially inwardly urged protrusions mating with and extending through said apertures, said protrusions having gripping contact points canted radially inwardly and away from said open end, the diameter defined by said contact points when said spring member is in relaxed position about said socket being less than the outside diameter of said circular member and said protrusions defiining a diameter greater than the outside diameter of said circular member, said spring spreading and the contact points sliding with respect to said circular member when the latter is inserted into said socket, but normally frictionally engaging the external surface of said circular member and cooperating with the walls of said socket defining said apertures to prevent said circular member from being withdrawn from said socket, the ends of said spring member being further spreadable externally of said socket to lift the gripping contact points from engagement with said circular member, freeing it for removal.

2. The connector of claim 1 comprising a threaded end afiixed to said socket away from the open end thereof, and wherein said socket contains three equidistantly spaced apertures and the spring member contains three mating protrusions.

References Cited UNITED STATES PATENTS 899,639 9/1908 Vibber 285-161 4 Martin 285-321 Thomas mas-3'65 Mall 285-305 X Payne 285-321 Munger 285-305 X Briegel et al 285-161 Ferguson et a1. 24-218X Kramer 285-321 X FOREIGN PATENTS 1,294,438 4/1962 France.

CARL W. TOMLIN, Primary Examiner.

D. W. AROLA, Assistant Examiner.

US. Cl. X.R.

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