CA1227828A - Blade terminal fuses with integrity indicator - Google Patents

Abstract

ABSTRACT

An integrity indicator formed as an illuminable bead is combined with the pair of flat termimal blades of a mini-ature plug-in fuse and is positioned in a central window pro-vided in the top wall of the insulator housing thereof. The housing defines a chamber having an open bottom and a central section with relatively narrow lateral sections in which up-per portions of the blades are secured. A fuse-wire extends across the central section conductively interconnecting the blades. The illuminable bead has a pair of wire leads extend-ing oppositely into the lateral sections of the chamber, each wire lead conductively contacting the upper portion of one of the blades and connecting the bead in parallel circuit with the fuse-wire. Clamping components formed on the interior of the top wall and on the upper portion of each terminal blade secure each wire lead in operative position. Embodiments include the fuse-wire integrally formed with the blades as a unitary structure and formed separately as a three piece structure wherein opposite ends of the fuse-wire are also secured by the clamping components, the latter being either in coplanar relation with the blades or disposed perpendicu-lar to the plane of the blades.

Description

1 32i~

. BLADE TERMINAL FUSE
WITH INTEGRITY INDICATOR

BACKGROUND OF THE INVENTION

Field of the invention Thus invention relates generally to miniature blade terminal fuse currently used in motor vehicle electrical ye .
terms and described in US S. Patent No. 3,909,767 granted to Ho L. Williamson en at and more particularly Jo a light India kitten capability for identifying a blown, open circuit condo-lion of such fuses Description of the prior art Recent models of motor vehicles have electrical Sue-terms equipped with fuse panel which u~ili2e miniature penal-lot blade terminal fuses, replacing the familiar cartridge type panels and fuses These blade terminal fuses a repro- -tentative construction of which is described in said William-son et at patent, provide two methods for identifying a blown, open circuit condition without removal of the fuse from the panel, namely, by a test instrument which may be applied to two test ponies accessible through openings in the top exposed surface of the fuse housing or by visual inspection of the . fuse-wire through the transparent housing The requirement of a test instrument, per so, is a considerable disadvantage.
Other disadvantages include the difficulty in Mohican visual and test instrument inspection due to the often limited access sublet of the panel and fuses and the failure of visual in-pectin even after removal of the fuse from the panel when the failure of the fuse is due to a substantially invisible hair-line open circuit resulting from a slight circuit over-load.

32~

There it therefore, a present need for providing such miniature, blade terminal fuses with a visible indicator of a blown, open circuit condition of the fuse which will make the blown fuse readily distinguishable from the other operate in fuses in 8 fuse block.

SUMMARY OF THE INVENTION

Among the objects of the invention it to satisfy the herein before described need by providing a miniature plug-in blade terminal fuse incorporating an illuminable bead post-toned in the top wall of the fuse and comprising solid state elements including an LED for providing the illumination. the several embodiments of the invention shall comprise few and simple parts and be inexpensive Jo manufacture in quantity production using methods of assembly compatible with existing production procedures and which Hall be dependable and effi-client in operation.

The invention embodies the combination of a readily visible integrity indicator with now conventional miniature, plug-in blade terminal fuse constructions which comprise on insulator housing and a pair of flat terminal blades in penal-lot coplanar spaced relation connected in a series circuit by a fuse-wire. The insulator housing is formed with a top wall, an interior chamber having relatively narrow lateral sections on opposite sides of a relatively wider central section and an open bottom. Upper portions of the terminal blades are retain-Ed as by snap-in engagement, in the lateral sections of the interior chamber, the lower portions of the blades projecting downwardly from the open bottom providing the exposed fuse terminals for removably engaging the socket of a fuse block

-2 If The invention features a central window provided in thy top wall of the housing above the central section of the chamber through which the integrity indicator, formed as an illuminable bead and positioned in the chamber is visible.
The illuminable bead has a pair of wire leads extending oppo-it'll into the lateral sections of the interior chamber, each wire lead conductively contacting the upper portions of one of the terminal blades and connecting the bead in parallel air cult with the fuse-wire. Clamping means for securing each wire lead in operative position includes a component integrally formed on the interior of the top wall of the housing, one component being located on each side of the central window for coating with a companion component formed on the end of the .
upper portion of each of the terminal blades. The snap-in en-gagement between an opening in the upper portion of each term-final blade and indentations.provi~ded:inthe housing which so-cures the blades on assembly with the housing also serves to retain the clamping engagement of the wire leads between the top wall of the housing and the ends of the upper portions of the blade.

In an embodiment of the invention in which the fuse-wire is integrally formed with the terminal blades as a unitary coplanar element, the clamping means component on each side of the window is formed as a rib extending from the top wall of the housing into the lateral section of the chamber and into a V-shaped cutout formed in the end of the upper port lion of the blade as the companion component of the clamping means. A section of each wire lead of the illuminable bead is thug formed with a loop and clamped in the V-shaped cutout by the downwardly extending rib.

In another embodiment, the fuse wiry is also ante-rally formed with eke terminal blades which are substantially in coplanar relation except for the clamping means companion components which are incorporated in integral tabs extending from the ends of the upper portion of the blades and disposed perpendicular to the plane of the blades. The clamping means component of the top wall is formed as a groove or cradle along which each wire lead of the illuminable bead extends, side portion of the groove being recessed to accommodate the integral tab which is formed with a central Unshaped cutout through which a portion of the wire lead extends for engage-mint and clamping retention by the tab.

Other modifications contemplate a five-piece asset-by in which the fuse-wire and terminal blade unitary element is formed in three separate parts, namely, a pair of separate terminal blades and a fuse-wire. The two clamping means embody iments herein before described for the three-piece construct lions may also be used to secure the opposite ends of a sepal rate fuse-wire in conductive engagement with each of the ton-final blades Thus, the wire leads of the illuminable bead and the end portions of a separate fuse-wire both extend through the clamping means. The illuminable bead is positioned in the window of the top wall of the housing as in the other embodiments while the fuse-wire it formed with a looped mid portion extending downwardly from the top wall and through the central section of the housing chamber.

I ~Z~Zf~

BRIEF DESCRIPTION OF THE DRAWINGS

¦ Fix. 1 is a perspective view of a miniature blade terminal fuse constructed with an integrity indicator embody-King the invention.

¦ Fig. 2 is a top plan view as teen along line 2-2 in-foe . 1 .

¦ Fig. 3 is a bottom view as seen along line 3-3 in foe . 1 .

¦ Fig. 4 is a side elevation view as seen along either of the lines 4-4 in Fig. 1.

Fig. 5 is a sectional view taken on line 5-5 in Fig.
showing interior structure of the fuss.

Fugue 6 and 7 are transverse sectional views taken n lines 6-6 and 7-7~ respectively, in Fig 5.

. Fix. 8 is a perspective view of the integrity India actor shown prior to assembly with the leads thereof preformed in accordance with the invention.

. Figs, 9 and 10 illustrate two steps in the assembly of the molded plastic housing with the other components come prosing the fuse shown in Foe. 1.

Fig. 11 is a schematic of the electronic components I

of the integrity indicator shown in parallel circuit with the fuse-wire in accordance with the assembly shown in Fig. 5.

Fig. 12 it a sectional view similar to Fix. 5 but showing a modified assembly construction in which three sepal rate parts comprise the fuse-wire and terminal blade combo-next.

Fix. 13 is an exploded perspective view of the into-grit indicator, fuse-wire and pair of blades removed from assembly in the housing shown in Fix. 12.

Fig. 14 is a sectional view similar to Figs. 5 and 12 but showing a modified construction of the three-piece fuse shown in Fig. 5.

it. 15 is an exploded perspective view of the into-grit indicator and combined fuse-wire and terminal blade eye-mint removed from the assembly in the housing shown in Fix, 14.

Figs. 16 and AYE are enlarged sectional views taken on lines 16-16 and AYE, respectively, in Fig 14 showing structural details Fig. 17 is a sectional view similar to Fig. 12 show-in a f~ve-piece modifiLcat~on of the structure and assembly shown in Fig. 14.

Fix. 18 is an exploded perspective view of the into-Wright indicator, fuse-wire and pair of blades removed from as-symbol in the housing shown in Fig. 17, and Fig. 19 it a fragmentary perspective view of the up-per end of one of the terminal blades one a modified form of damping component for the integrity indicator lead wire.

I

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in detail to Figs. 1 to 7, inclusive, of the drawings, 20 denotes a therapies miniature, plug-in, blade terminal fuse with an integrity indicator embodying the invention comprising an insulator housing 21~ a combined blade terminal and fuse-wire element 30 and an integrity indicator in the form of an illuminable read 27. As seen in Figs. 5 and 7, element 30 is formed of sheet metal as a pair of spaced parallel blades 31 integrally interconnected at a mid portion thereof by a link fashioned as a fuse-wire 350 Each blade 31 ha a centralized opening 32 providing the female component of a snap-in connection between the element 30 and housing 21 and an inner or upper end formed with a generally V-shaped -quote 33 providing for the securing of illuminable bead 27 in position in housing 21 and making electrical contact there-with. Each blade 31 has a lower or outer end portion 34 ox-tending beyond the bottom 22 as a blade terminal or male con-tact for engaging a cooperating female contact of a fuse 30ck-et (not shown).

Housing 21, molded of sultabl~ plastic material have in electrical insulating properties, such as, nylon, polyp Turin or the like, comprises a relatively long and narrow top wall 23 and a pair of opposite sidewalls 24 connected a-long opposite lateral margins by end wall 25, all forming an interior chamber which s open along bottom 22~ Top wall 23 is formed with a central opening aye providing a window in I

which illuminable bead 27 is located and end walls 25 each have a vertical rib aye for engagement by means provided in the fuse socket (not shown) for resilient retention therein f fuse 200 Sidewalls 24 are each contoured to provide a pair f lateral panels 24b symmetrically arranged on opposite tides f a central panel aye 9 the latter being outwardly stepped to provide a relatively wide central chamber portion aye there-between which communicates with top wall opening aye. The opt owing lateral panels 24b are relatively more closely spaced o accommodate blades 31 there between and have aligned indent anions 24c which engage openings 32 as male components of the nap-in connection between housing 21 and element 30. Each of a pair ox interior rib 26 extends downwardly from top wall 23 between lateral panels 24b of the opposite sidewalls 24 into he V-shaped cutout 33 of each blade 31.

Illuminable bead 27, as seen in Fig 11, may come prose a pair of Lids arranged in parallel in opposite pox laxity and in series with a protecting resistor 27aaIlencased in suitable translucent material, such as, epoxy, lass or the like, in accordance with conventional solid state Tahitian-logy and has a pair of oppositely extending wire leads 29.
Each lead 29 is sized in length and shaped to extend between the medial leg aye of V-shaped cutout 33 and top wall 23, a-long the curved edge of leg aye and into the bottom of cutout 33 for locking engagement therein by rib 26.

I I

One of the advantages of the construction embodying the invention is the close parallel of the method of asset-.
blink the three components of fuse 20 to the production method disclosed in said Williamson et at patent and currently in use. It will be apparent that Lo practice the assembly is per-formed on a downwardly vertical direction, namely, with the strip 36 and housing 21 rotated clockwise 90 from the post-lion shown in Figs. 9 and OWE

. Strip 36, being made of a metal having properties suitable for fuse-wire use as teen in Fig. 9, is precut with a series of centrally located rectangular openings 37 swooper-ted by transverse portions 38 connecting longitudinally ox tending border portions which when suitably die cut, as here-inciter described, form the spaced parallel blades 31. like-wise, a looped wit no structure aye extents through each opening 37 properly aligned with respect to a small opening in each border portion of strip 36 providing fuse-wire 35 and openings 32, respectively, in assembled fuse 20, The leading end of each border portion of strip 36, as seen in Fix. 10, is formed with a V-shaped cutout 33 having a longer medial leg aye and a shorter lateral leg 33b.

Assembly may be performed as a continuous process hereby housing 21 is orientated in an inverted positive. If-umlnable bead 27, having oppositely extending wire leads 29 reshaped as shown in Fix. 8, is also inverted and fed by rivulet into the upfacin~ open bottom of the interior chamber o teat in central opening aye in top wall 23 with wire leads 29 extending between lateral panels 24b and across interior its 26, The leading end of strip 36 is then inserted into the nt~rior chamber Jo that wire leads 29 are clamped by V-shaped I

cutouts 33 against interior ribs 26. In fully inserted post-lion, reached when medial legs aye of blade 31 engage a pro-:
tionofw~re leads I adjacent illuminable bead 27 which pro lions in turn abut the interior surface of top wall 23, on-denotations 24c simultaneously snap into engagement in openings 32 for retention of the three components in operative asset-by a fuse 20~ Die cutting means snot shown) then severs the leading, assembled, section from strip 36 in the region of the adjacent transverse portion 38, cutting out the latter and forming both the beveled ends of blade portions 34 of the as-symboled fuse 20 and the V-shaped klutz 33 as a new leading end of strip 36.

A modification shown in Figs. 12 and 13 contemplates a five-piece fuse 40 comprising a housing 41, a pair of spaced parallel blades 51, the upper ends of which clamplngly engage both wire leads 49 of illuminable bead 47 and end portions aye of fuse-wire 55. Housing 41 may be substantially identical to housing 21 of fuse 20 and it shown to include a top wall 43 having a central opening aye, opposite sidewalls 44 formed with lateral panels having indentations 44c for engaging open-ins 52 in blades 51, an interior chamber open at bottom 42 and a pair of interior ribs extending downwardly from top wall 43. Each blade 51 has the upper end formed with a V-shaped cutout 53 also provided with longer medial leg aye and a shorter lateral leg 53b similar to V-shaped cutout 33 of blades 31, A modified structure for securing the illuminable bead in position in electrical conductive engagement in series circuit with the terminal blades is shown in Fits 14, 15, 16 and AYE for a three-piece fuse and in Figs. 17 and 18 for a ' -10-f~ve-piece construction.

Fuse 60, shown in Figs. 14 and 15, comprises a house in 61, a combined blade terminal and fuse-wire element 70 and an illuminable bead 67 having oppositely extending wire leads 69. Element 70 is similar to element 30 of fuse 20 in the pro-vision of fuse-wire 75 integrally connecting parallel blades I having openings 72 for snap-in engagement by indentations 64c and an outer end portion 74 extending beyond the bottom 62 of housing 61 but differs from the complete coplanar con-figuration of element 30 in the formation of an integral jab 73 extending from thy inner end of each blade 71 and disposed in a plane perpendicular to thaw of blades 71 and fuse-wire 75, tabs 73 being formed with U-shaped cutouts aye.

Housing 61, likewise, is a modified form of housing 21, having the interior surface of top wall 63 formed with thickened portions 63b extending longitudinally from opposite sides of central opening aye each portion 63b having a medial groove 63c which may have inclined walls, as seen in Fig. AYE.
A relatively deep depression or recess 66 terminates each groove 63c and has a central longitudinal projection aye seen in Figs. Andy 16 as a clamping component for wire lead 69 coating with a respective integral tab 73 and cutout aye. The lateral panels 64b of housing sidewalls 64 are slightly nary rower than lateral panels 24b of housing 21 providing a eon trial chamber portion aye which is wider than central chamber portion aye for inclusion of tabs 73 therein enabling insert lion of element 70 through the open bottom of the chamber dun in assembly. Grooves 63c and the clamping afforded by tabs 7' and recesses 66 enable use of wire leads 69 of bead 67 dip-posed in a straight line configuration.

Fuse 80, shown in Figs. Andy 18, is a flve-piece structure similar to fuse 40 in that parallel t~rrninal blades 91 are separate from fuse-wire 95~ Otherwise fuse 80 embodies the modifications of fuse 60. Thus, housing 81 it similar to housing 61, haven a top wall 83 formed with interior grooves terminating in recesses 86 and projections aye, sidewalls 84 formed to provide on enlarged central chamber portion, an open bottom 82 through which outer end portions 94 of blades 91 project and indentations 84c for snap-in engagement with open-ins 92 of blades OWE The upper ends of blades 91 are also formed with tabs 93 and U-shaped cutouts aye which cocci with recesses 86 and projections aye to simultaneously clampingly secure both the wire leads 89 of bead 87 and the end portions aye of fuzzier 95.

Fig 19 shows a modified upper end of a blade 56 having a tab 57 cutout and offset from the plane of the blade instead of the perpendicular configuration between tabs 73, 93 and blades 71, 91, respectively, or the coplanar relation of Y-shaped cutouts 33 and 53. Wire leads 297 49, 69 or 89 and fuse wire end portions aye and aye may thus be retained between end portions aye and tab 57 to clampin~ly engage suit-ably provided clamping components in top walls 23, 43 63 or I

It is to be understood that instead of molding the indentations 24c, 44c, 64c and 84c in housings 21, 41, 61 and 81 for snap-in engagement with blade openings 32, 52 72 and 92, respectively, assembly between the respective housings and blades may be accomplished utilizing cold staking or ultrasonic melting means and methods in the well known manner.

Illuminable beads 27, 47, 6Z and 87 may be of any desired shape other Han that shown in the drawings and the windows provided in top walls 23, 43, 63 and 83 appropriately shaped and Jay be closed rather than open or formed with a magnifier to intensify the light emitted by the LED. The if-luminable beads may also include a single LED requiring often-talon means between the fuse housing and the socket Rosetta-ale for proper polarity in the D. C. circuits of motor vow-ales . Also, in accordance with LED technology, the resistor aye may be an active P-N junction properly polarized with no-spent Jo the LED whereby each LED has a P-N unction in series therewith. Ike LED and P-N junction combinations are in urn in parallel to achieve the universal polarity I the circuit shown in Fix. 11.

- In use, any opening of the fuse-wire 35, 55, 75 or 95; as by blowing or otherwise results in the lighting of the respective illuminable bead while the load remains in the circuit.

The blade terminal fuses with the integrity indict-ion herein disclosed are seen to achieve the several objects of the invention and to be well adapted to meet conditions of practical use. As various possible embodiments might be made of this invention, and as various changes might be made in the disclosed fuses, it is to be understood that all matters here-in set forth or shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.

Claims (9)

What is claimed is:
1. Claim 1. A blade terminal fuse having an integrity indicator comprising an insulator housing formed with a top wall, an interior chamber having relatively narrow lateral sections on opposite sides of a central section and an open bottom, a pair of flat terminal blades in coplanar spaced re-lation having upper portions located in said chamber lateral sections and lower portions projecting downwardly from said open bottom, a fuse-wire extending through said chamber cen-tral section conductively connected in series with said ter-minal blades, said top wall being formed with a central window above said chamber central section and being formed on the in-terior side thereof on opposite sides of said window with a component of a clamping means, said integrity indicator being an illuminable bead located in said chamber central section in register with said top wall window and having wire leads ex-tending oppositely into said chamber lateral sections con-ductively contacting said terminal blade upper portions where-by said illuminable bead is in series with said blades and in parallel with said fuse-wire, said terminal blade upper por-tions each being formed with a companion component of said clamping means, the clamping means securing each of said wire leads in said conductive contact with each terminal blade up-per portion.
2. Claim 2. The blade terminal fuse defined in claim 1 in which said pair of flat terminal blades and fuse-wire are formed as an integral structure of a fuse metal.
3. Claim 3. The blade terminal fuse defined in claim 1 in which said pair of flat terminal blades are separate com-ponents and said fuse-wire is a discrete element having oppo-site ends extending into said chamber lateral sections, said clamping means also securing said fuse-wire opposite ends in conductive contact with each terminal blade upper portion as said series connection with the terminal blades.
4. Claim 4. The blade terminal fuse defined in claim 1 in which said housing clamping means components are interior ribs having free ends extending toward said open bottom, said clamping means companion component being a cutout formed in each terminal blade upper portion, said wire leads being re-tained in said cutouts in said conductive contact by said rib free ends. .
5. Claim 5. The blade terminal fuse defined in claim 4 in which said cutouts have medial and lateral legs bordering said cutouts, said medial legs being longer than the lateral legs and serve to clamp portions of said wire leads adjacent the illuminable bead against said top wall.
6. Claim 6. The blade terminal fuse defined in claim 4 in which said cutouts each includes a tab attached to the bot-tom of the cutout and extending in offset parallel relation to the plane of said blades.
7. Claim 7. The blade terminal fuse defined in claim 1 in which said clamping means companion components each com-prise a tab extending perpendicularly to the plane of said blades and formed with cutouts, said top wall clamping means components each including a depression recessed from the in-terior surface of the top wall in registered alignment to re-ceive one of said tabs therein, each of said illuminable bead lead wires extending along the interior surface of said top wall, across the depression and being engaged in the cutout of one of said tabs as said conductive contact.
8. Claim 8. The blade terminal fuse defined in claim 7 in which said pair of terminal blades, perpendicular tabs and fuse-wire are formed as an integral structure of a fuse metal.
9. Claim 9. The blade terminal fuse defined in claim 7 in which said fuse-wire is a discrete element having opposite ends extending into said chamber lateral sections, said clamp-ing means also securing said fuse-wire opposite ends in con-ductive contact with each of said tabs as said series connec-tion with the terminal blades.