GB1564131A

GB1564131A - Electric fuseholders

Info

Publication number: GB1564131A
Application number: GB1736576A
Authority: GB
Original assignee: CONTACTUM Ltd
Current assignee: CONTACTUM Ltd
Priority date: 1977-04-26
Filing date: 1977-04-26
Publication date: 1980-04-02

Description

(54) IMPROVEMENTS IN AND RELATING TO ELECTRIC FUSEHOLDERS (71) We, CONTACTUM LIMITED., a British company of Victoria Works, Edgware Road, London, N.W.2., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to electric fuseholders and in particular to a fuseholder arranged to accept a cartridge fuse by means of a movable but captive fuse carrier.

According to the present invention there is provided an electrical fuse holder comprising a mounting member of insulating material having assembled therewith a body member of insulating material to retain contact members and terminal members therebetween, said mounting member being apertured to receive a fuse carrier member arranged for withdrawal from the assembly only to an extent sufficient to allow the insertion or withdrawal of a cartridge fuse, said fuse carrier being arranged upon reinsertion in said assembly to engage said fuse with said contact members, said fuse carrier being retained within said assembly by pressure exerted by said contact members upon said cartridge fuse, wherein said fuse carrier is formed so as to be capable of insertion into said aperture in said mounting member from the outer side thereof prior to the assembly of said body member with said mounting member and said body member includes a portion co-operating with said mounting member when assembled therewith to prevent removal of said fuse carrier through said aperture.

Preferred features and advantages of the invention will become apparent from the following description of embodiments of the invention. The description is given with reference to the drawings, in which: Figure 1 is a front view of a switch and fuse unit including a pilot lamp; Figure 2 is a perspective view of the assembly of Figure 1, from one side and below, showing the fuse carrier in its withdrawn position; Figure 3 is a half-sectional inverted plan of the assembly of Figures 1 and 2; Figures 4a and 4b are respectively an end and a side elevation of the fuse carrier forming a part of the assembly of Figures 1 to 3; Figure 5 is a front view of one element of the assembly of Figures 1 to 3, showing electrical contacts which receive the fuse; Figure 6 is a rear view of the assembly of Figures 1 to 3; and Figure 7 is a detail, partly in section, of a connection used in the assembly; Figure 8 is a front view of a fuse unit; Figure 9 is a side view of the fuse unit of Figure 8, showing the manner of inserting the fuse; Figure 10 is a rear view of the fuse unit of Figures 8 and 9. with the contact assembly and fuse carrier removed; Figure 11 is a front view of the contact assembly of the fuse unit of Figures 8 to 10; Figures 12 and 13 are respectively an inverted plan and a side elevation of the fuse carrier of the fuse unit of Figures 8 to 11.

Figures 1 to 7 illustrate a fuse and switch unit embodying the invention and including a pilot lamp.

It will, however, be understood that the elements of this assembly other than those pertaining directly to the fuse holder do not constitute essential features of the present invention.

The assembly 10 of Figures 1 to 3 and 6 comprises a mounting member 11 of insulating material provided with apertures 12 for fixing screws and pierced by three generally rectangular apertures 13, 14, 15, that serve respectively to receive a captive fuse carrier 16, a switch rocker 17 and a transparent pilot-lamp cover member 18.

The margin of aperture 13 that accepts fuse carrier 16 is bevelled at 13a to provide access for a tool to be inserted below a flat rectangular cover portion 16a of the fuse carrier to withdraw the latter from its mounting. As best seen in Figures 4A and 4B, fuse carrier 16, which is most suitably a unitary plastics moulding, includes rectangular cover portion 16a, of a size to fit snugly but without binding within aperture 13 of mounting member 11, being located flush with the surface of mounting member 11 by lips 13c, 13d as later described. From the inner surface of cover portion 16a extends a square-section pillar 16b, and transverselv to pillar 16b and longitudinally of the cover portion extend parallel crossmembers 16c, 16d spaced apart by a distance d slightly greater than the diameter of a cartridge fuse to be used in the assembly.

The inner cross member 16d is narrow enough to pass the jaws of contact members positioned to engage the fuse. The length 1 of fuse carrier 16 somewhat exceeds the length of a fuse which it is to carry.

Advantageously, pillar 16b merges into cross-members 16c, 16d arcuately as seen in Figure 4A, the curved surface having a radius corresponding to that of the fuse.

Below cross-member 16d and integral with it extends a projection 16e which, in the complete assembly and as shown in Figure 3 engages behind a lip 13b, formed at the margin of aperture 13 and bounding the recess into which cover portion 16a fits, thus preventing the withdrawal of fuse carrier 16 from mounting member 11.

Behind mounting member 11 and abutted against its central portion is a body member 20 of insulating material having in it, as seen in Figures 3 and 6 a recess 21 having a deeper central portion 21a into which projection 16e of fuse carrier 16 enters and shallower end portions 21b in which are mounted contact clips 22. 23 arranged, when the fuse carrier is fully inserted in the assembly, to engage the end contact members of a fuse F placed in carrier 16. The inturned free ends of contact clips 22. 23 are so positioned that when the fuse carrier 16 is fully inserted in its mounting an inward force is exerted on the fuse, thus urging cover portion 16a into contact with the outer surface of lip 13b and with outer surfaces of lips 13c, 13d formed at the opposite longitudinal side of recess 13.

The lateral distance between corresponding edges of lips 13b and 13c, 13d is slightly wider than the width of upper cross-member 16c of fuse carrier 16 and the longitudinal separation between lips 13c, 13d sightly exceeds the corresponding dimension of pillar 16b. Body member 20 is provided with a pillar portion 24 which abuts pillar 16b of fuse carrier 16 and assists in guiding its withdrawal from and replacement in its operative position.

It will thus be understood that fuse carrier 16 is formed so as to be capable of insertion into the aperture 13 in mounting member 11 from the outer side thereof prior to the assembly of body member 20 with mounting member 11, body member 20 including a portion 24 co-operating with mounting member 11 when assembled therewith to prevent removal of the fuse carrier 16 through the aperture 13.

In assembling the arrangement, the fuse contact clips and associated conductors, which may differ in accordance with the particular application of the fuse holder as will later be described, are placed in body member 20, fuse carrier 16 is placed in mounting member 11 and the latter is then placed upon body member 20 with pillar 24 of the latter entering into a mating recess portion 13e formed in mounting member 11.

The assembly may then be inserted and body member 20 and mounting member 11 secured together by any preferred means, conveniently by screws passing through holes in body member 20 and engaging in screw-threaded holes in mounting member 11 as shown at 25. After body member 20 has been secured to mounting member 11 the fuse carrier 16 is held captive in the assembly and can be withdrawn forwards only sufficiently far to allow removal and replacement of the fuse F.

Behind pilot lamp cover member 18 is disposed a pilot lamp 26 (Figure 6). This lamp is most conveniently a small neon lamp having a suitable current-limiting resistor in one of its connecting leads 27, 28. Lamp 26 is retained by any convenient means, in the illustrated embodiment body member 20 is provided with a suitably shaped and positioned projection 20a which retains lamp 26 in contact with cover member 18. Lamp connection leads 27, 28 are connected to contact members of the assembly as required for a particular application. As shown in full line, lead 27 is taken to a contact member 29 which extends from fuse clip 22 and lead 28 is taken to a contact member 30 which extends from fuse clip 23.

With this arrangement the pilot lamp glows if the fuse blows. Alternatively, the pilot lamp may be used to indicate that the controlled load is switched on. Lead 28 is then, as shown in broken line at 28', connected to a contact member 31 that extends from a load-connection terminal 32 of an electric switch mounted within portion 20b of body member 20. The switch included within body member portion 20b may be of any preferred kind and for the present application is most advantageously double-poled, one pole connecting a terminal A to a terminal B and the other pole connecting a terminal C by way of fuse F to a terminal D.

Obviously the fuse holder arrangement above described may be included in devices other than that described or used to provide a simple fused connection, in which case each of the fuse clips 22, 23 will be electrically connected to a respective terminal lead as shown for fuse clip 22 in Figures 3 and 5.

The fuse clip 22 consists of a generally U-shaped member having one limb inwardly and then outwardly curved, the other limb being generally flat. At the foot of the flat limb a hole is formed in the clip, through which passes a stem portion 29 of a conductive strip 22a secured to terminal D.

A very convenient means of securing the pilot lamp connecting leads 27, 28 to contact members 29, 30 and 31 is illustrated by Figure 7. The contact member 31 is reduced in width at shoulders 31a and the end portion of the reduced portion 31b is provided with an aperture 31c in which is inserted a bared end portion 28a of the otherwise insulated lead 28. Around reduced portion 31b of contact member 31 is placed a helical compression spring 32 which is held in a substantially compressed condition by lead 28. This means for connecting pilot lamp leads is also useful in devices other than that here described and not necessarily including a fuse holder.

Figures 8 to 13 illustrate a fuse unit embodying the invention and offering some advantages over the arrangement of Figures 1 to 7.

The fuse unit 40 shown in Figures 8 to 10 comprises a mounting member 41 of insulating material provided with apertures 42 for fixing screws and pierced by a rectangular aperture 43 that receives a captive fuse carrier 44.

The margin of aperture 43 that accepts fuse carrier 44 is bevelled at 43a to provide access for a tool to be inserted beneath a flat rectangular cover portion 44a of fuse carrier 44 when it is desired to withdraw the fuse.

As best seen in Figures 12 and 13, fuse carrier 44, which is preferably a unitary plastics moulding, includes, extending rearwardly from cover portion 44a a pillar 44b of rectangular cross-section. Near to cover portion 44a and preferably integral therewith is a cross-member 44c having therein a rectangular recess 44d for improved moulding. Cross member 44c has a bevelled edge 44e for convenience in inserting a fuse laterally into the carrier.

Spaced from cross member 44c by somewhat more than the diameter of the fuse end caps is a further cross member 44f of which the side remote from cross member 44c is bevelled for convenience in moulding. Cross member 44f is narrow enough to pass between the jaws of the fuse contact members described later. The mutually facing surfaces of cross members 44c and 44f are not parallel, but slightly slanted to aid the insertion of the fuse while closely locating it when in place. From the end of pillar 44b there is formed transversely to cross member 44f a retaining portion 44g of which a part 44h extends beyond cross member 44f to engage mounting member 41 and prevent removal of the fuse carrier from the assembly. Part 44h of retaining portion 44f engages in a recess, below level 43a formed in mounting member 41 at the margin of aperture 43. Retaining portion 44h is narrower than the recess so that when the fuse carrier 44 is fully withdrawn it may be rocked as shown in Figure 9, to allow ready insertion of a fuse in the direction indicated by arrow A, until the lower end of the fuse abuts the lower margin of aperture 43, when the fuse carrier may be restored to an upright position and urged into the mounting member, the end caps of fuse 45 then engaging in fuse clips 22, 23 to retain the fuse and fuse carrier in place, as well as to establish electrical contact to the fuse. To extract a fuse, the carrier 44 is withdrawn and tilted upwardly, thus allowing the fuse to drop from its lower end.

At the rear of mounting member 41, aperture 43 is surrounded by a table portion 41a of the same thickness as slanting rim portions 41b that extend around the periphery of member 41. At one side of aperture 43 are formed shelf portions 41c that are abutted by the inner surface of fuse carrier cover portion 44a to locate its outer surface flush with that of mounting member 41. Between shelf portions 41c is a notch that guides pillar 44b of fuse carrier 44 for movement inwards and outwards of mounting member 41 with sufficient clearance to allow the rocking movement above described. This feature may also be included in the embodiment of Figures 1 to 7.

Against table portion 41a there is applied a body member 50 that is recessed at 51 to receive contact members 52, 53 and terminal members 54, 55 generally similar to the corresponding members of the embodiment of Figures 1 to 7. Body member 50 is secured to table 41a by screws passing through holes 50a formed in the body member and engaging in corresponding holes 41e formed in table portion 41a of the mounting member.

Body member 50 also includes a forwardly projecting pillar 56 that enters the notch to prevent disengagement of the fuse carrier 44 from the assembly of mounting member 41 and body member 50.

Body member 50 may also be recessed to receive neutral conductor terminals 57, 58 joined by a strap 59.

Mounting member 41 may have one of the fixing apertures 42 lined with a metal bushing 42a connected to an earth terminal 42b.

The embodiment of Figures 8 to 13 may be modified to include a pilot lamp arranged similarly to that of the preceding embodiment.

WHAT WE CLAIM IS: 1. An electrical fuse holder comprising a mounting member of insulating material having assembled therewith a body member of insulating material to retain contact members and terminal members therebetween, said mounting member being apertured to receive a fuse carrier member arranged for withdrawal from the assembly only to an extent sufficient to allow the insertion of withdrawal of a cartridge fuse, said fuse carrier being arranged upon reinsertion in said assembly to engage said fuse with said contact members, said fuse carrier being retained within said assembly by pressure exerted by said contact members upon said cartridge fuse, wherein said fuse carrier is formed so as to be capable of insertion into said aperture in said mounting member from the outer side thereof prior to the assembly of said body member with said mounting member and said body member includes a portion co-operating with said mounting member when assembled therewith to prevent removal of said fuse carrier through said aperture.

2. A fuse holder in accordance with claim 1, wherein said mounting member includes a slot in which said pillar portion of said fuse carrier is slidingly movable and wherein said co-operating portion of said body member is a pillar portion entering said slot so as to prevent movement of said fuse carrier laterally of the direction of its sliding movement.

3. A fuse holder in accordance with claim 1 or 2 wherein said fuse carrier comprises a cover portion fitting within an aperture in said mounting member and located flush with the surface of the mounting member by shoulders in said aperture.

4. A fuse holder in accordance with claim 3. wherein said fuse carrier further includes a pillar portion extending inwardly of the assembly from said cover portion and having extending therefrom first and second cross members spaced apart to accept said fuse cartridge therebetween. the innermost of said cross members being narrow enough to pass between the jaws of said contact members.

5. A fuse holder in accordance with claim 4, wherein said fuse carrier includes an integral retaining portion extending laterally from the inner end of said pillar to abut against the inner side of a portion of said mounting member thereby to prevent removal of said fuse carrier from the assembly.

6. A fuse holder in accordance with any one of claims 1 to 5, wherein said fuse carrier is arranged to be tiltable with respect to said mounting member when in its withdrawn position thereby to facilitate the insertion and withdrawal of said fuse cartridge.

8. A fuse holder in accordance with any one of claims 1 to 7, wherein said body member further includes an electrical switch having an actuator member extending through said mounting member.

9. A fuse holder in accordance with any one of claims 1 to 8, wherein said mounting member is provided with a transparent pilot lamp cover member behind which is supported a pilot lamp connected to terminals of said assembly.

10. A fuse holder in accordance with claim 9, wherein wire leads extending from said pilot lamp pass through apertures in said terminal members and are retained therein by helical springs surrounding said terminal members, said springs bearing against said leads and against shoulders formed on said terminal members.

11. An electrical fuse holder substantially as herein described with reference to Figures 1 to 7 or Figures 8 to 13 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

the fixing apertures 42 lined with a metal bushing 42a connected to an earth terminal 42b.

The embodiment of Figures 8 to 13 may be modified to include a pilot lamp arranged similarly to that of the preceding embodiment.

WHAT WE CLAIM IS:

1. An electrical fuse holder comprising a mounting member of insulating material having assembled therewith a body member of insulating material to retain contact members and terminal members therebetween, said mounting member being apertured to receive a fuse carrier member arranged for withdrawal from the assembly only to an extent sufficient to allow the insertion of withdrawal of a cartridge fuse, said fuse carrier being arranged upon reinsertion in said assembly to engage said fuse with said contact members, said fuse carrier being retained within said assembly by pressure exerted by said contact members upon said cartridge fuse, wherein said fuse carrier is formed so as to be capable of insertion into said aperture in said mounting member from the outer side thereof prior to the assembly of said body member with said mounting member and said body member includes a portion co-operating with said mounting member when assembled therewith to prevent removal of said fuse carrier through said aperture.

2. A fuse holder in accordance with claim 1, wherein said mounting member includes a slot in which said pillar portion of said fuse carrier is slidingly movable and wherein said co-operating portion of said body member is a pillar portion entering said slot so as to prevent movement of said fuse carrier laterally of the direction of its sliding movement.

3. A fuse holder in accordance with claim 1 or 2 wherein said fuse carrier comprises a cover portion fitting within an aperture in said mounting member and located flush with the surface of the mounting member by shoulders in said aperture.

4. A fuse holder in accordance with claim 3. wherein said fuse carrier further includes a pillar portion extending inwardly of the assembly from said cover portion and having extending therefrom first and second cross members spaced apart to accept said fuse cartridge therebetween. the innermost of said cross members being narrow enough to pass between the jaws of said contact members.

5. A fuse holder in accordance with claim 4, wherein said fuse carrier includes an integral retaining portion extending laterally from the inner end of said pillar to abut against the inner side of a portion of said mounting member thereby to prevent removal of said fuse carrier from the assembly.

6. A fuse holder in accordance with any one of claims 1 to 5, wherein said fuse carrier is arranged to be tiltable with respect to said mounting member when in its withdrawn position thereby to facilitate the insertion and withdrawal of said fuse cartridge.

8. A fuse holder in accordance with any one of claims 1 to 7, wherein said body member further includes an electrical switch having an actuator member extending through said mounting member.

9. A fuse holder in accordance with any one of claims 1 to 8, wherein said mounting member is provided with a transparent pilot lamp cover member behind which is supported a pilot lamp connected to terminals of said assembly.

10. A fuse holder in accordance with claim 9, wherein wire leads extending from said pilot lamp pass through apertures in said terminal members and are retained therein by helical springs surrounding said terminal members, said springs bearing against said leads and against shoulders formed on said terminal members.

11. An electrical fuse holder substantially as herein described with reference to Figures 1 to 7 or Figures 8 to 13 of the accompanying drawings.