Protector for electric circuits

[57] ABSTRACT

A female connector is connected to a conductor and normally telescopes over a male connector on one end of a fuseholder, but is will respond to a separating force, smaller than the elastic limit of that fuseholder, to release that male connector; and a sleeve of insulating material normally encases and insulates the connection between that male connector and that female connector.

Claims, 7 Drawing Figures

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Patented Aug. 14, 1973 3,753,192

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3,753,192

PROTECTOR FOR ELECTRIC CIRCUITS

This is a continuation of application Ser. No. 871,233 filed Nov. 3, 1969, which was a division of application Ser. No. 796,520 filed Feb. 4, 1969 now U.S. Pat. No 3,518,600.

This invention relates to improvements in Protectors For Electric Circuits. More particularly, this invention relates to improvements in fuseholders and in separable connectors used therewith.

It is, therefore, an object of the present invention to provide an improved fuseholder and an improved separable connector Used therewith.

It is desirable to interpose fuseholders between the sockets for street lamps and the power lines connected to those sockets; because the fuses within those fuseholders can provide important electrical protection. That electrical protection can be impaired and those fuseholders can be damaged, when vehicles strike and break off those street lamps; because the conductors within those street lamps can, as those street lamps are broken off, apply destructive tensile forces to the fuseholders and to the connections between those fuseholders and the power lines. It would be desirable to equip a fuseholder, to be interposed between the socket of a street lamp and the power line connected to that socket,, with a separable connector which would respond to forces smaller than the elastic limit of that fuseholder to separate from that fuseholder; and it would be desirable: to provide that separable connector with insulation which would: remain with that separable connector as it is separated from that fuse-holder. Such a separable connector and the insulation therefor would keep that fuseholder from being subjected to destructive forces, and would continue to effectively insulate that separable connector after it was separated from the fuseholder. It is, therefore, an object of the present invention: to equip a fuseholder, to be interposed between the socket of a street lamp and the power line connected to that socket, with a separable connector which will respond to forces smaller than the elastic limit of that fuseholder; to separate from that fuseholder, and to provide that separable connector with insulation which: will remain with that separable connector as it is separated from that fuseholder.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description several preferred embodiments of the present invention are shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing;

FIG; 1 is a partially sectioned view of a fuseholder, of a separable connector used with that fuseholder, of a sleeve of insulating material used with that separable connector, and of two boots of insulating material used with that fuseholder and with that separable connector,

FIG; 2 is a cross-sectional view that is taken along the plane indicated by the line 2—2 in FIG. 1;

FIG. 3 is a partially broken-away, side elevational view of one of the boots of insulating material shown in FIG. 1,

FIG. 4 is a partially sectioned side view showing the fuseholder of FIG; 1 assembled with a different separa2 ble connector and with a different boot for that separable connector,

FIG. 5 is a partially sectioned view of the different boot shown in FIG. 4,

FIG. 6 is a sectional view through the different boot shown in FIG. 4, and it is taken along the plane indicated by the line 6—6 in FIG. 5, and

FIG. 7 is a partially sectioned view of a different fuseholder and of a boot of insulating material therefor.

Referring to the drawing in detail, the numeral 20 generally denotes a fuseholder of the type shown in my U.S. Pat. No. 3,356,806 for Protectors For Electric Circuit which was granted Dec. 5, 1967; and that fuseholder has a body portion 21 and a body portion 23. The body portion 23 has an external thread 25 at the left-hand end thereof, has a hexagonal wrenchreceiving surface 27 adjacent that thread, and has a male connector 22 projecting outwardly beyond the right-hand end thereof. The male connector 22 has an enlarged diameter portion 24 that abuts the body portion 23. The body portion 21 has a nut 26 with an internal thread rotatably mounted on the right-hand end thereof and has a terminal 76, with an elongated recess in the shank thereof, projecting outwardly beyond the left-hand end thereof. The body portions 21 and 23 are hollow; and they coact to form a recess which will accomodate a cartridge type electric fuse, all in the manner shown by my said patent.

The numeral 28 generally denotes a separable connector of tubular configuration; and that separable connector has a continuous and unbroken sleeve-like portion 30 at the right-hand thereof, and has elongated, flexible fingers 34, 36, 38 and 40 at the left-hand end thereof which define an elongated recess 32. The fingers 34,,36, 38 and 40 have radially extending flanges at the free ends thereof; and the inner surfaces of those fingers can be spread far enough apart to accommodate the male connector 22 on the body portion 23 of the fuseholder 20. As a result, the fingers 34,36,38 and 40 enable the separable connector 28 to act as a female connector. However, a split ring 42 of resilient material, such as spring steel, encircles the free ends of the fingers 34, 36, 38 and 40; and that split ring biases those free ends into a position wherein they define an opening with a diameter smaller than the diameter of the male connector 22 on the body portion 23. This means that the male connector 22 must distend that split ring as it is moved into the elongated recess 32 defined by the fingers 34,36,38 and 40. After that male connector has been moved into the elongated recess 32, the force which the split ring 42 applies to the fingers 34, 36, 38 and 40 will hold those fingers in intimate engagement with the male connector 22, thereby ₅₅ providing good mechanical securement and good electrical contact between those fingers and that male connector.

The numeral 44 denotes a sleeve of insulating material, such as neoprene; and the inner diameter of the right-hand end of that sleeve is slightly smaller than the diameter of the separable connector 28. As a result, that right-hand end of that sleeve has a press fit with that separable connector. An annular recess 46 is provided in the sleeve 44; and that recess is dimensioned 65 ^to accommodate the split ring 42. A further annular recess 48 is provided in the sleeve 44; and that recess is dimensioned to accommodate the radially directed flanges at the free ends of the fingers 34; 36,38 and 40

3,753,192 of the separable connector 28. A larger diameter recess 50 is provided in the left-hand of the sleeve 44; and the inner diameter of that sleeve is slightly smaller than the diameter of the body portion 23 of the fuseholder 20. As a result, the recess 50 will provide a close fit with that body portion when the left-hand end of the sleeve 44 is telescoped over that body portion. A shoulder 52 is provided in the sleeve 44 between the annular recess 48 and the larger diameter recess 50; and that shoulder will help prevent accidental separation of that sleeve from the separable connector 28.

The numeral 54 denotes an insulated conductor which has the right-hand end thereof freed of insulation; and that right-hand end is telescoped within the elongated recess in the shank of the terminal 76 of the body portion 21 of the fuseholder 20. Once that end of that conductor has been telescoped within that recess, the terminal 76 will be crimped, staked, or otherwise deformed to provide a permanent electrical and mechanical connection between that terminal and that end of that conductor. The numeral 56 denotes an insulated conductor which has the left-hand end thereof freed of insulation; and that left-hand end is telescoped within the continuous and unbroken sleeve-like portion 30 at the right-hand end of the separable connector 28. Once that end of that conductor has been telescoped within that portion, that portion will be crimped, staked or otherwise deformed to provide a permanent electrical and mechanical connection between that conductor and the separable connector 28.

While the separable connector 28 will be permanently connected to the conductor 56 by the crimping, staking, or other deforming of the sleeve-like portion 30, that separable connector will have only a frictional engagement with the male connector 22 of the body portion 23 of the fuseholder 20. That frictional engagement will provide holding forces which are strong enough to prevent accidental separation of the separable connector 28 from the male connector 22, and which are strong enough to provide a low resistance electrical connection between that separable connector and that male connector; but those forces will be smaller than the elastic limit of the fuseholder 20. This is important; because it enables the separable connector 28 to release the male connector 22 before the fuseholder 20 can be subjected to potentially hurtful forces. Also, the separable nature of the connectors 22 and 28 is important in rendering a broken-off street lamp electrically “dead” -- so persons coming in contact with that street lamp will not receive an electrical shock.

The numeral 58 generally denotes a boot of insulating material, such as neoprene; and that boot has a frusto-conical left-hand end 60 and a cylindrical right-hand end 62. Annular ribs 64 are provided at the exterior of the frusto-conical end 60, and annular ribs 66 are provided at the interior of the cylindrical end 62. The unstressed diameters of the annular ribs 66 at the interior of the cylindrical end 62 are slightly smaller than the diameter of the body portion 21, and hence those annular ribs will provide a close fit with that body portion as those ribs are distended and telescoped over that body portion. The smallest diameter of the frustoconical left-hand end 60 of the boot 58 is smaller than the diameter of the insulation on the smallest-diameter wire which will be connected to the terminal 76 of the fuseholder 20. As a result, that frusto-conical left-hand end will be able to provide a close fit with the insulation on that conductor, as that left-hand end is distended to permit that conductor to be passed through it.

FIG. 3 shows the configuration of the boot 58 as that boot is sold; and it will be noted that the boot 58 in FIG. 1 has had part of the left-hand end 60 thereof cut off. That part was cut off because the insulation on the conductor 54 has a diameter which is appreciably larger than the inner diameter of the smallest diameter portion of the left-hand end 60 of the boot 58, as that boot is sold. Specifically, it will be noted that there are eight ribs 64 at the exterior of the left-hand end 60 of the boot 58 shown in FIG. 3, but there are only seven ribs 64 at the exterior of the boot 58 shown in FIG. 1 -- the left-handmost rib 64 and the portion of the left-hand end 60 between that first rib and the second rib having been cut off.

In determining where the frusto-conical left-hand end 60 of the boot 58 should be cut, one end of the insulated conductor 54 will be telescoped through the cylindrical end 62 of the boot 58 and moved into engagement with the inner surface of the frusto-conical lefthand end 60. When a light pressure on the conductor 54 is unable to cause the left-hand end of that conductor to move any further through the frusto-conical lefthand end 60 of the boot 58, the portion of that frustoconical left-hand end into which the insulated conductor 54 did not extend will be cut off, by appropriate use of a knife, scissors or the like. The cut will be made to the left of the right-handmost annular rib 64 through which the end of the insulated conductor 54 did not extend; and hence that rib and the part of the frustoconical left-hand end 60 which is adjacent to, and slightly to the right of, that rib will have to be distended as the conductor 54 is subsequently pressed through that frusto-conical left-hand end. After the frustoconical left-hand end 60 of the boot 58 has been cut, the insulated conductor 54 will be introduced into that boot by first passing it through the frusto-conical lefthand end 60 and then moving it through the cylindrical end 62. At such time, the bared end of that conductor will be telescoped into the terminal 76 of the body portion 21 of the fuseholder 20 and then that terminal will be crimped, staked or otherwise deformed to provide a permanent electrical and mechanical connection between that conductor and that terminal. Thereafter, the boot 58 will be shifted to the right, relative to the conductor 54, until the cylindrical end 62 telescopes onto the body portion 21 of the fuseholder 20.

The engagement between the frusto-conical end 60 of the boot 58 and the insulation on the conductor 54 will be snug and will be water-resistant. Similarly, the engagement between the annular ribs 66 at the inner surface of the cylindrical end 62 of that boot and the body portion 21 of the fuseholder 20 will be snug. Those annular ribs will coact with that body portion to provide a plurality of spaced seals; and those seals will effectively resist the entry of water into the joint between the boot 58 and the fuseholder 20.

The numeral 68 generally denotes a boot which can be identical to the boot 58. The annular ribs 69 within the cylindrical, left-hand end 70 ofthe boot 68 will be distended to telescope over the right-hand end of the sleeve 44; and those ribs will coact with that sleeve to provide a plurality of spaced seals. The frusto-conical right-hand end 72 of the boot 68 will be cut to provide a snug and intimate engagement with the insulation on the conductor 56; and, as with the boot 58, there are

3,753,192

6 just seven annular ribs 74 at the exterior of the righthand end 72 of the boot 68. The boot 68 will coact with the sleeve 44 on the separable connector 28 and with the insulation on the conductor 56 to provide waterresistant joints on opposite sides of the electrical connection between that conductor and that separable connector.

The fuseholder 20 has a water-tight seal between the body portion 21 and the terminal 76 thereof, has a water-tight seal between the body portion 23 and the male connector 22 thereof, and will provide a water-resistant seal between the body portions 21 and 23 thereof. The boot 58 will coact with the body portion 21 and with the insulation on the conductor 54 to keep water away from the electrical connection between that conductor and the terminal 76; and the sleeve 44 of insulating material and the boot 68 will coact with the body portion 23 and with the insulation on the conductor 56 to keep water away from the electrical connection between that conductor and the separable connector 28 and away from the electrical connection between that separable connector and the male connector 22. As a result, the fuse within the fuseholder 20 and the connections between that fuseholder and the conductors 54 and 56 are protected against moisture and water.

The conductor 56 will be connected to the “line” side of the circuit, and the conductor 54 will be connected to the “load” side of the circuit. The male connector 22 will thus be the “load” connector and the female connector 28 will thus be the “line” connector of ³⁰the connection provided by those two connectors; and this is important, because that male connector will be exposed whereas that female connector will be protected whenever that connection is interrupted; Specifically, the portion of the sleeve 44 of insulating material which defines the recess 50 will project outwardly beyond the left-hand end of the female connector 28, and will thus keep that female connector from contacting any nearby objects or the ground as that female connector and the male connector 22 are separated. Further , that portion of the sleeve 44 of insulating material will keep a repairman from being shocked as he picks up the Tine” connector of the connection provided by the male connector 22 and the female connector 28.

It should also be noted that the boot 68 will remain in engagement with the conductor 56 and with the sleeve 44 of insulating material whenever the connection provided by the male connector 22 and the female connector 28 is interrupted. Specifically, the annular ribs 69 at the interior of the cylindrical portion 70 of that boot will continue to remain in engagement with the exterior of the right-hand portion ofthe sleeve 44 of insulating material, and the small diameter righthand end 72 of that boot will remain in engagement with the insulation on the conductor 56. As a result, that boot Will continue to encase and to insulate the connection between the conductor 56 and the female connector 28 whenever the connection between that female connector and the male connector 22 is interrupted. The overall result is that the female connector 28 will continue to be protected and shielded and the connection between that female connector and the conductor 56 will continue to be encased and shielded whenever the connection provided by the male connector 22 and the female connector 28 is interrupted.

To restore the connection provided by the male connector 22 and the female connector 28 the repairman will grip the cylindrical end 62 of the boot 58, will grip the cylindrical portion 70 ofthe boot 68, and will guide the tapered tip of the male connector 22 into the female connector 28. Thereafter, that repairman will apply relatively strong telescoping forces to the body portion 21 of the fuseholder 20 and to the female connector 28 to effect full telescoping ofthe male connector 22 into that female connector. Because the split ring 42 will cause the ends ofthe fingers 34,36,38 and 40 to strongly resist the telescoping of the male connector 22 into the female connector 28, the repairman may want to press against the left-hand end ofthe body portion 21 of the fuseholder 20 and to grip the sleeve-like portion 30 of the female connector 28; and the walls of the boots 58 and 68 will be made thin enough to enable that repairman to do so. Consequently, although the connection provided by the male connector 22 and the female connector 28 is a “blind” connection, the boots 58 and 68 will enable the repairman to make that connection and to sense that the connection has been made.

Where the walls of the boots 58 and 68 are made quite thin, the frusto-conical ends of those boots can tend to tear as those frusto-conical ends are telescoped over, and are then slid along, the insulation on the conductors 54 and 56. The walls of the boots 58 and 68 can be made quite thin, and yet the frusto-conical ends of those boots can be made very resistant to tearing, by providing the annular ribs 64 and 74, respectively, at the exteriors of the frusto-conical ends 60 and 72 ofthe boots 58 and 68.

Referring to FIG. 4, the numeral 82 denotes a conductor which can be identical to the conductor 54, and which will be electrically and mechanically connected to the terminal, not shown, on the left-hand body portion of the fuseholder 20. The junction between that conductor and that terminal will be encased and insulated by a boot 58 which can be identical to the boot 58 shown in FIGS. 1 and 3. The numeral 84 denotes a female connector with a rod-like projection 86 at the right-hand end thereof and with four circumferentially spaced fingers adjacent the left-hand thereof. Because FIG. 4 is a side view, only two of those fingers, namely the fingers 88 and 90, are shown. The female connector 84 of FIG. 4 will closely resemble the separable connector 28 in FIGS. 1 and 2, except for the fact that the female connector 84 has a rod-like projection 86 at the right-hand end thereof whereas the separable connector 28 has a sleeve-like portion 30 at the right-hand end thereof.

A split ring 92 encircles the free ends of the fingers 88 and 90 plus the other two fingers of the female connector 84, in the same manner in which the split ring 42 encircles the free ends ofthe fingers 34,36,38 and 40 of the female connector 28. The split ring 92 will normally hold the free ends of the fingers 88 and 90 and of the other two fingers of the female connector 84 closer together than the diameter of the male connector 22 on the body portion 23 ofthe fuseholder 20; but that split ring will yield to permit that male connector to be telescoped into position between the free ends of those fingers. The numeral 93 denotes a sleeve of insulating material which can be identical to the sleeve 44 of insulating material in FIGS. 1 and 2; and that sleeve of insulating material will enclose and insulate the fingers 88 and 90 and the other two fingers of the female connector 84, will enclose and insulate the split ring 92,

3,753,192 and will enclose and insulate the body portion 23 of the fuseholder 20.

The numeral 94 denotes a connector which has a tubular projection 96 extending outwardly from the lefthand end thereof, which has a cylindrical socket 98 in the right-hand end thereof, which has a cylindrical socket 100 in the right-hand end thereof, which has a set screw 102 communicating with the cylindrical socket 100, and which has a second set screw, not shown, communicating with the cylindrical socket 98. The tubular projection 96 is dimensioned to telescope freely over the rod-like projection 86 on the female connector 84; but that tubular projection will be crimped, staked or otherwise deformed into permanent engagement with that rod-like projection. Consequently, the connector 94 will, effectively, serve as part of the female connector 84. The socket 98 is dimensioned to accommodate the bared end of an insulated conductor 104, and the socket 100 is dimensioned to accommodate the bared end of an insulated conductor 106. The set screw 102 will be tightened to provide a good electrical and mechanical connection between the connector 94 and the conductor 106; and the second set screw, not shown, will be tightened to provide a good electrical and mechanical connection between the conductor 104 and the connector 94. The connector 94 and the female connector 84 are used where it is desirable to interconnect two conductors to the male connector 22 of the fuseholder 20.

The numeral 108 denotes a boot which has a cylindrical left-hand end with internal annular ribs 110, which has a cylindrical central portion with external annular ribs 112, and which has two frusto-conical sections 114 and 116 at the right-hand end thereof. The diameters of the ribs 110 are slightly smaller than the outer diameter of the right-hand portion of the sleeve 93 of insulating material which encases the fingers 88 and 90 plus the other two fingers of the female connector 84; and hence those ribs will be distended as they are telescoped over that portion of that sleeve. Thereafter, the restorative forces within those ribs and within the cylindrical left-hand end of the boot 108 will cause those ribs to provide a plurality of water-resistant seals with that portion of the sleeve 93 of insulating material.

The frusto-conical section 114 of the boot 108 will accommodate the conductor 104, which has the lefthand end there-of held within the socket 98 of the connector 94; and the frusto-conical section 116 of that boot will accommodate the conductor 106, which has the left-hand end thereof held within the socket 100 of that connector. The unstressed inner diameter of the outer end of each of the frusto-conical sections 114 and 116 will be smaller than the diameter of the insulation of the conductors 104 and 106; and hence those outer ends will be distended as the conductors 104 and 106 ⁵⁵are telescoped through those sections. Thereafter, the restorative forces within those outer ends will provide water-resistant seals between the boot 108 and the insulation on those conductors.

The sleeve 93 of insulating material will encase and ⁶⁰insulate the connection between the male connector 22 and the female connector 84; and the boot 108 will encase and insulate the connection between that female connector and the connector 94, and also will encase and insulate the connection between the connector 94 ⁶⁵and the conductors 104 and 106. In the event a force is applied to the conductor 82 or to either of the conductors 104 and 106 which causes the female connector 84 to move away from the male connector 22 on the body portion 23 of the fuseholder 20, the sleeve 93 will remain in engagement with that female connector, and 5 the boot 108 will remain in engagement with that sleeve and with those conductors. As a result, the female connector 84, the connector 94, the connection between them, and the connection between the connector 94 and the conductors 104 and 106 will con10 tinue to be encased and insulated after the female connector 84 has been separated from the male connector 22 on the body portion 23 of the fuse-holder 20.

As shown by FIG. 7, the boot 108 can be assembled with the body portion of a fuseholder which has a tubu15 lar terminal that is large enough to accommodate the ends of two conductors. Specifically, the boot 108 can have the internal annular ribs 110 at the cylindrical left-hand end thereof distended to telescope over the right-hand body portion of a fuseholder 120 which has 20 a tubular terminal 122 that is large enough to accommodate the bared ends of two conductors 124 and 126. The frusto-conical sections 114 and 116 at the righthand end of the boot 108 will snugly accommodate the insulation on the conductors 124 and 126; and the 25 bared ends of those conductors will be held by the crimped, staked or otherwise deformed tubular terminal 122.

The annular ribs 122 on the boot 108 strengthen the cylindrical central portion of that boot; but they permit ³⁰ that cylindrical central portion to be flexible. If desired, external annular ribs, similar to the annular ribs 64 and 72 of FIG. 1 can be formed on the frusto-conical sections 114 and 116 at the right-hand end of the boot 108.

While the fuseholders, separable connectors, insulating sleeves, and insulating boots of the present invention are very useful in street lighting circuits, they are useful elsewhere too. In fact, those fuseholders, separable connectors, insulating sleeves, and insulating boots are usable anywhere external forces can accidentally separate a fuseholder from the “line” or “load” side of a circuit.

The boots 58, 68 and 108 and the sleeves 44 and 93 will be made from material that is resilient as well as non-conductive . . . as a result, those boots and those sleeves will be able to withstand blows and stresses — when the street lamp or other power consuming device with which they are used is struck — which rigid and brittle elements could not withstand. The overall result is that the fuseholders, separable connectors, insulating sleeves and insulating boots of the present invention can minimize and largely eliminate the risk of electrical shocks when street lamps and other power consuming devices are struck.

Whereas the drawing and accompanying description have shown and described several preferred embodiments of the present invention it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.