BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side cross-sectional view of a compression-type connector for a wire having a stranded central conductor in accordance with a first embodiment of the present invention prior to inserting a wire into the axial bore in the compression sleeve (for clarity, the connector terminal, which is threadingly attached to the connector terminal adapter, is not shown in FIG. 1 and FIGS. 2-10 that illustrate various embodiments of the present connector).
FIG. 2 shows a wire having a stranded central conductor with an end of the wire stripped to expose a length of the stranded central conductor.
FIG. 3 is a side cross-sectional view of a compression-type connector of FIG. 1 illustrating the insertion of the prepared end of the wire of FIG. 2 into the axial bore in the compression sleeve.
FIG. 4 is a side cross-sectional view of the compression-type connector of FIG. 3 showing the splaying of the strands of wire comprising the central conductor by the conical centerpost when the prepared end of the wire is further advanced into the axial bore in the compression sleeve and into the axial cavity in the connector body.
FIG. 5 is a side cross-sectional view of the compression-type connector of FIG. 4 showing the splaying and lateral separation of the strands of wire comprising the central conductor by the conical centerpost when the prepared end of the wire is yet further advanced into the axial cavity in the connector body.
FIG. 6 is a side cross-sectional view of the compression-type connector of FIG. 4 showing the splaying and lateral separation of the strands of wire comprising the central conductor by the conical centerpost when the prepared end of the wire is fully advanced into the axial cavity in the connector body and the compression sleeve advanced into the axial cavity in the body of the connector and in locking engagement therewith.
FIG. 7 is a partially cross-sectional view of a compression-type connector in accordance with a preferred embodiment of the present invention.
FIG. 8 is a partially cross-sectional view of a compression-type connector in accordance with the preferred embodiment of the present invention illustrated in FIG. 7 with the end of a cable inserted thereinto before compression.
FIG. 9 is a partially cross-sectional view of the compression-type connector in accordance with FIGS. 7 and 8 illustrating the secure holding of the cable by the connector when the compression sleeve is advanced over the trailing end of the connector body.
FIG. 10 is an enlarged view of the cable and connector of FIG. 9 when compression is completed by the full advancement of the compression sleeve over the connector body.
FIG. 11 is a top view of a standard terminal connector of the type used with a threaded bolt wherein the trailing end has a threaded bore adapted to matingly receive the threaded connector terminal adapter on the leading end of a connector in accordance with all foregoing embodiments of the present connector.
FIG. 12 is a top view of a spade lug adapted to be threadably attached to a connector in accordance with the present invention.
FIG. 13 is a top view of a banana plug adapted to be threadably attached to the connector terminal adapter on the leading end of any of the stranded wire connectors of the present invention.
FIG. 14 is an enlarged cross-sectional view of the banana plug terminus of FIG. 13 showing the banana plug terminus attached to the preferred embodiment of the stranded wire connector illustrated in FIGS. 7-10.
FIG. 15 is a partially cross-sectional view of a compression-type connector in accordance with the preferred embodiment of the present invention illustrated in FIG. 7 with a cable inserted thereinto before compression wherein the connector comprises locking means operable for impeding the retraction of the compression sleeve after compression is complete.
FIG. 16 is a partially cross-sectional view of a compression-type connector in accordance with FIG. 15 illustrating the secure holding of the cable by the connector when the compression sleeve is advanced over the trailing end of the connector body and the locking means is engaged subsequent to compression.
FIG. 17 is a cross-sectional view of an improvement to a compression connector in accordance with the prior art wherein the connector is improved by the inclusion of a spiral ridge or thread on the outer surface of the centerpost to enhance the wire-gripping strength of the connector following compression, and providing means for an installer to determine when the end of a wire is fully inserted within the axial cavity of the connector body.
FIG. 18 is an enlarged view of a portion of the threaded conical centerpost on the connector of FIG. 17.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a compression-type connector 10 operable for attachment to a wire having a stranded central conductor in accordance with a first embodiment of the present invention. The connector 10 is illustrated in cross-sectional side view in an open position prior to attachment to a wire. The connector 10 includes a tubular connector body 11 having an axial cavity 12 therewithin. The leading end 12′ of the axial cavity 12 is contoured and has the form of the surface of a hemitorus. A conical centerpost 13 is disposed within the axial cavity 12 at the leading end thereof. The base 14 of the conical centerpost 13 is circular and centered within the leading end 12′ of axial cavity 12. The apex 15 of the conical centerpost is axially disposed to be colinear with the axis of the axial cavity. The leading end of the connector body 11 is attached to at least one, and more preferably two, as shown in the figures, connector terminal adapter 16 having a threaded interior surface 17. The connector terminal adapter(s) 16 provide means for connecting an electrically conductive terminus such as a lug, pin or the like, the terminus having a threaded base portion similar to the termini shown in FIGS. 11-13, to the compression-type connector 10. A compression sleeve 18 having a leading end 18′, which may or may not be contoured, and an axial bore 19 is slidingly mounted within the axial cavity 12 and held therewithin by detent 19′.
FIG. 2 shows a wire 20, such as, for example, a speaker wire, having a stranded central conductor 21 with an end of the wire 20 being stripped to expose a length L of the stranded central conductor 21. FIG. 3 is an elevational cross-sectional view of the compression-type connector of FIG. 1 illustrating the insertion of the prepared end 21 of the wire 20 of FIG. 2 into the axial bore 19 in the compression sleeve until the leading end of the stranded center conductor 21 makes contact with the apex 15 of the conical centerpost 13. As the wire is further advanced through the axial bore 19 and into the axial cavity 12, the strands of wire comprising the central conductor 21 are splayed, being forced radially outwardly by the conical centerpost 13 as shown in FIG. 4. FIG. 5 shows the further splaying and lateral separation of the strands of wire comprising the central conductor 21 by the conical centerpost 13 when the prepared end of the wire is yet further advanced through the axial bore 19 of the compression sleeve 18 until the stripped length L of the wire 20 has been separated by the conical centerpost. When the wire 20 is fully advanced through the axial bore 19 in the compression sleeve 18 and into the axial cavity 12 of the connector body, the forwardmost ends of the strands comprising the center conductor are forced to curve and bend rearwardly in the axial cavity 12 of the body 11 by the contoured leading end 12′ of the axial cavity 12.
When the wire is fully advanced into the axial cavity 12, as shown in FIG. 5, a compression tool (not shown) is employed to force the compression sleeve 15 forwardly within the axial cavity 12 toward the leading end 12′ thereof as shown in FIG. 6. When the compression sleeve 18 is fully advanced, the leading end 18′ of the compression sleeve 18 is urged against the bent strands of wire 21 comprising the central conductor, trapping the strands of wire 21 between the leading end 18′ of the compression sleeve 18 and the connector body 11. A second detent 19″ engages a mating detent rest in the wall of the axial cavity causing locking engagement therewith. After the wire 20 is securely attached to the connector 10 in the manner described above, a suitable electrically conductive terminus such as a spade lug or banana plug having a threaded portion can be attached to either of the connector terminal adapter(s) 16. The assembly provides secure attachment between the connector terminus and the wire.
A key feature of the first embodiment of the connector of the present invention presented above is the curvature of the leading end of the axial cavity. During advancement of the wire 20, the splayed strands of wire 21 bend outwardly and follow the curved path established by the hemitoroidal surface at the leading end of the axial conduit. When the compression sleeve is fully advanced, the leading end 18′ of the compression sleeve, which can be flat or have a toroidal shape that mates with the curvature of the leading end of the axial cavity 12, traps the recurved ends of the stranded wire against the connector body such that the strands of wire are perpendicular to the axis of the axial bore of the compression sleeve at the forwardmost portion of the wire strands. The wire/connector assembly thus formed resist separation of the wire from the connector (and the selected terminus) when tension is applied to the wire.
A disadvantage of prior art stranded wire connectors such as disclosed by Korte et al. '895 is that after compression, the connector is easily removed from the wire by the application of axially directed tension on the wire. This disadvantage is due to the absence of a positive wire strand-gripping mechanism in the connector. All surfaces holding the wire within the prior art connectors are smooth and provide only minimal gripping. As will be illustrated later, when FIGS. 17 and 18 are discussed, the present invention also includes a modification of the prior art stranded wire connector disclosed in Korte et al. '895 that improves the gripping force of the connector. Notwithstanding the aforesaid improvement in Korte et al '895 that will be discussed later, a more preferred embodiment of a stranded wire connector that overcomes the problem of secure attachment inherent in the prior art connectors is presented below.
Turning now to FIG. 7, a preferred embodiment of the stranded wire connector of the present invention is illustrated in partially cross-sectional view at 70. The connector 70 comprises a connector body 71 and a compression sleeve 72. The connector body 71 has a threaded leading end 73 integral therewith, and a tubular trailing end 74 having a cylindrical cavity 75 therewithin. A rigid centerpost 76 projects rearwardly from the leading end of the cylindrical cavity 75 and is centered within and coaxial with the cylindrical cavity 75. The centerpost 76 has a straight spiral-threaded shaft 77 and a conical tip 78 on the trailing end thereof. The tubular trailing end 74 of the connector body 71, which may have longitudinal slots in the wall thereof to facilitate deformation of the trailing end 74 radially inwardly during compression, preferably has a roughened inner surface 79 such as one or more annular ridges operable for capturing and holding a wire (20 in FIG. 2) after compression as will be discussed below. The compression sleeve 72, which is slidably mounted over the trailing end 74 of the connector body 71, has a rearwardly-tapered axial bore 80. That is, the inner diameter of the axial bore at the leading end of the compression sleeve is greater than the diameter of the axial bore at the trailing end of the compression sleeve.
The installation of the connector 70 onto the end of a wire having a stranded conductor is illustrated in FIGS. 8 and 9. FIG. 8 is a partially cross-sectional view of the compression-type connector 70 in accordance with the preferred embodiment of the present invention illustrated in FIG. 7, with the end 21 of a wire 20 having a stranded center conductor inserted through the axial bore 80 of the compression sleeve 72 and into the axial cavity 75 in the trailing end of the connector body 72. As the conductive strands of wire 21 are forced in a forward direction (i.e., toward the leading end of the axial cavity 75) by application of a forward twisting force, the strands encounter the conical tip 78 of centerpost 76 and are separated and forced radially outwardly, stretching the outer jacket of the wire. When the wire 20 is fully advanced and the tips of the wire strands are abutting the leading end of the cavity 75, the compression sleeve is advanced over the trailing end 74 of the connector body 71 by means of a compression tool (not shown) or by threaded engagement between the outer surface of the trailing end of the connector body and the inner surface of the compression sleeve. As the compression sleeve advances toward the leading end of the connector body, the connector body is deformed radially inwardly by the tapered axial bore 80 in the compression sleeve 72 to compress the strands of wire 21 between the roughened wall of the axial cavity 75 and the threaded exterior surface of the centerpost.
FIG. 9 is a partially cross-sectional view of a compression-type connector in accordance with FIGS. 7 and 8 illustrating the secure holding of the cable by the connector when the compression sleeve is fully advanced over the trailing end of the connector body. FIG. 10 is an enlarged view of the wire and connector assembly of FIG. 9 when compression is completed by the full advancement of the compression sleeve over the connector body. The tapered axial bore 80 of the compression sleeve 72 forces the trailing end 74 of the connector body 71 inwardly such that the splayed wire 21 is trapped between the roughened inner surface 79 of the cavity 75 and the threaded shaft 77 of the centerpost 76. The spiral thread 77 on the shaft of the centerpost 76 and the surface 79 of the cavity 75, which may optionally have one or more annular ridges on the surface thereof to increase holding force, serve to provide compression points through 360 degrees and provide additional resistance to the retraction of the wire 20 from the connector 70 after compression is complete.
It is an important feature of the connector of the present invention that it be adaptable for use with a variety of mating connector terminal receptacles. FIGS. 11-13 illustrate a variety of conductive connector terminals adapted to be removably attached to the connector 70. FIG. 11 is a top view of a standard terminal connector 110 of the type used with a threaded bolt-type mating terminal receptacle. The trailing end 111 of terminal 110 has a threaded bore 112 adapted to matingly receive the threaded connector terminal adapter 73 on the leading end of connector 70. FIG. 12 is a top view of a spade lug 120 adapted to be removably attached to the threaded leading end 73 of connector 70. FIG. 13 is a top view of a banana plug 130 adapted to be threadably and removably attached to the leading end of connector 70. FIG. 14 is an enlarged cross-sectional view of the banana plug terminus of FIG. 13 showing the banana plug terminus 130 attached to the preferred embodiment of the stranded wire connector 70 illustrated in FIGS. 7-10.
It may be desirable to provide the connector 70 with locking means operable for preventing or impeding removal of the compression sleeve 72 from the connector body 71 when compression is complete. A modification of the preferred embodiment of connector 70 including such locking means is shown in FIGS. 15 and 16. FIG. 15 is a partially cross-sectional view of a compression-type connector in accordance with the preferred embodiment of the connector 70 with a cable inserted thereinto before compression wherein the connector comprises locking means 151 and 151′ operable for impeding or resisting the retraction of the compression sleeve from the connector body after compression is complete. In the example shown in FIGS. 15 and 16, the locking means 151 and 151′ are an annular ridge on the outer surface of the trailing end of the connector body and an annular groove on the inner surface of the axial bore of the compression sleeve respectively. FIG. 16 is a partially cross-sectional view of the compression-type connector in accordance with FIG. 15 illustrating the secure holding of the cable by the connector when the compression sleeve is advanced over the trailing end of the connector body and the locking means 151 and 151′ is engaged subsequent to compression.
As discussed above, in the connector of Korte et al. '895, the unstripped cable is pushed onto a smooth conical prong. As a rear plug (i.e., compression sleeve) is moved inwardly to lock the cable into the connector, the annular space between the wall of the axial cavity and the conically-tapered center prong is reduced by the addition of a wedge-type action of the plug. The limitations of this design it is necessary for the installer to assure that the wire is pushed forward sufficiently onto the conical prong to result in the required holding force because the stranded wire has a tendency to slip rearwardly off of the smooth surface of the prong as the connector is being handled and compressed, and because the wire strands remain in the same plane as the pulling force. The holding power relies on the wire being inserted to the correct depth into the axial cavity as well as the exact sizing of the plug and body to a limited size of wire.
An improvement in the connector of Korte et al. '895 that overcomes these limitations is illustrated in FIGS. 17 and 18. FIG. 17 is a cross-sectional view of an improvement to the compression connector 172 of Korte et al. '895 wherein the connector 172 is improved by the inclusion of a spiral ridge or thread 170 on the outer surface of the centerpost 171 to enhance the wire-gripping strength of the connector following compression, and providing means for an installer to determine when the end of a wire 173 is fully inserted within the axial cavity 174 of the connector body 175. FIG. 18 is an enlarged view of a portion of the threaded conical centerpost 171 on the connector 172 of FIG. 17. If the connector body 175 is made to be deformable radially inwardly, as, for example, by the inclusion of a plurality of longitudinal slots in the wall thereof in the manner well known in the art, the compression sleeve 176 can be slidably mounted over the trailing end of the connector body 175 by enlarging the leading end of the axial bore 177 in the compression sleeve. If the axial bore is tapered, advancement of the compression sleeve 176 over the connector body 175 toward the leading end thereof will force the wall of the axial cavity 174 radially inwardly during compression to clamp the end of the wire 173 between the threaded prong and the wall of the axial cavity.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. For example, the connector terminal adapter on the leading end of the connector body may be either a threaded male or a threaded female fitting, depending on the mating attachment means presented on the conductive terminal to which the connector body is to be attached. Further, it will be obvious to the artisan that the inclusion of a detent between the connector body and the compression sleeve of all the connectors disclosed herein will resist and/or prevent the removal of the compression sleeve from the connector body after compression is complete. Similarly, the artisan will appreciate that one or more annular ridges on the wall of the axial cavity will improve the wire-holding force of the connector and further resist separation of the end of the wire from the connector. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Patent Application
20070259562
