GB1581398A

GB1581398A - Fuse clip assemblies

Info

Publication number: GB1581398A
Application number: GB4466278A
Authority: GB
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1976-09-27
Filing date: 1977-09-27
Publication date: 1980-12-10
Also published as: GB1581397A; JPS56175955U; CH622126A5; DE2742967A1; JPS5341754A

Description

( 21) Application No 44662/78

( 62) ( 31) ( 22) Filed 27 Sep 1977 Divided out of No 1581397 Convention Application Nos 726966 ( 32) Filed 27 Sep 1976 in 726965 ( 33) United States of America (US) ( 44) Complete Specification Published 10 Dec 1980 ( 51) INT CL 3 H 01 H 85/00 II 85/20 ( 52) Index at Acceptance H 2 E 10 B 24 3 C 2 A 3 C 2 C 3 D 4 3 E 19 7 E 1 H 1 N 637 646 649 664 700 706 708 710 715 H 2 G DD ( 72) Inventors: ERNEST GERARD DENIGRIS ALBERT JOHN TUTKO ( 54) IMPROVEMENTS IN OR RELATING TO FUSE CLIP ASSEMBLIES ( 71) We, WESTERN ELECTRIC COMPANY, INCORPORATED, of 222 Broadway, New York City, New York State, United States of America, a Corporation organized and existing under the laws of the State of New York, United States of America, 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 de-

scribed in and by the following statement:-

This invention relates to a fuse clip assembly for making mechanical and electrical contact with an inserted tubular alarm type fuse.

Fuse clips and fuse clip assemblies are well known in the art In a typical fuse clip assembly there is a first clip for making mechanical and electrical contact with one terminal of the fuse and a second clip, spaced apart from the forward clip, for making electrical and mechanical contact with a second terminal of the fuse This arrangement serves well for two terminal fuses where electrical current passes through the fuse only while the fuse element is whole or unblown When the element of such a fuse is overloaded its element opens and the passage of electrical current is stopped.

There is another type of tubular fuse, known as an alarm fuse, which includes an alarm indicator conveniently in the form of a third terminal for making electrical contact with an alarm circuit when the fuse element opens Thus, additional restraints must be placed on any fuse clip assembly designed to accept such an alarm fuse.

These restraints arise from the fact that the fuse body must be held in a fixed positive relative to the alarm terminal of the assembly in order to ensure proper electrical contact when the fuse is blown Also, the alarm terminal of the fuse must contact the alarm terminal of the fuse assembly with a force sufficient enough to break through any layer of dirt or oxide that might be on the terminal and with a force sufficient to maintain electrical contact for alarm purposes.

According to the present invention there is provided a fuse clip assembly for use with tubular alarm type fuses comprising first and second fuse clips which are spaced apart and adapted to mate with an apply spring force to a corresponding terminal of an inserted fuse, the first and second fuse clips having means for restricting longitudinal movement of an inserted fuse, means being provided for receiving an alarm indicator of an inserted fuse for affording an indication when the said alarm indicator is extended to an alarm condition.

In one arrangement according to the invention a mounting board may be provided on which said fuse clips are mounted, said mounting board having an upturned edge with a slot therein, said slot being in longitudinal alignment with said first and second fuse clips and adapted to receive a visual alarm indicator of an inserted fuse to afford a visual indication when said indicator is extended to an alarm condition.

In another arrangement according to the invention a mounting board may be provided on which said fuse clips are mounted, the means for receiving an alarm indicator conveniently taking the form of an alarm terminal which is spaced apart in longitudinal alignment with said first and second fuse PATENT SPECIFICATION ( 11) 1 581 398 1 581 398 clips to receive the alarm indicator of an inserted fuse when said indicator is extended to an alarm condition.

The alarm terminal may be provided with a slot which is adapted to receive a visual alarm indicator of an inserted fuse to afford a visual indication when said indicator is extended to an alarm condition, the area around the slot of said alarm terminal advantageously being curved towards said fuse clips for retaining the extended alarm indicator of an inserted fuse.

The alarm terminal may be formed of conducting material which makes electrical contact with the alarm indicator of an inserted fuse to afford an electrical indication when said alarm indicator is extended to an alarm condition.

Advantageously the first and second fuse clips and the alarm terminal may each be of unitary construction, the first and second fuse clips and the alarm terminal each preferably including a wire wrap leg, each wire wrap leg conveniently including a locking tab for retaining the associated clip or terminal against the mounting board.

Advantageously, the first and second fuse clips and the alarm terminal may each be provided with a second leg having a locking tab thereon for retaining the associated clip or terminal against the mounting board.

In carrying out the invention the means for restricting longitudinal movement of an inserted fuse in said first and second fuse clips may take the form of indents in said first and second clips, or alternatively may take the form of an indent in the one of said fuse clips nearest the alarm indicator of an inserted fuse and a spring on the other of the said fuse clips for urging an inserted fuse longitudinally toward said one of said fuse clips.

In accordance with one embodiment of the invention a fuse clip assembly is provided having two fuse clips and an alarm terminal spaced in a line along the axis of the inserted fuse These may conveniently be referred to as the load terminal and line terminal and the alarm terminal.

Power to the fuse is supplied via the line terminal which connects to the fuse at the front end of the fuse body The load terminal connects to the fuse at the rear end of the fuse and is designed to apply forward pressure to the fuse body along the longitudinal axis of the fuse.

The line terminal is designed to prevent the fuse from being pushed too far forward by the forward pressure of the load terminal It is formed from a single piece of material which is thick enough to satisfy the wire wrap terminal requirements while at the same time satisfying the fuse clip spring force requirements This result is achieved by reducing the thickness of the material only where the material is bent to form the U of the clip A fuse clip of this form forms the basis of our co-pending patent application No 40122/77 (Serial No 1581397) This reduction in thickness, a process called coining, serves to reduce the spring force the desired amount without either affecting the physical size of the wire wrap leg or the structural resistivity of the clip The clip may be mounted through a hole in a flat panel by a locking tab on the wire wrap leg A second shorter leg integral with the fuse clip may also be provided so as to provide mechanical stability for mounting purposes thereby substantially reducing manufacturing costs.

The alarm terminal of the assembly is shaped to accept the alarm terminal of the fuse only when the fuse is blown and to maintain electrical contact therewith The alarm terminal is mounted forward of the line terminal a distance such that electrical contact is not made with the fuse alarm terminal while the fuse remains unblown.

The pressure exerted by the load terminal on the fuse body toward the alarm terminal serves to ensure that proper electrical contact is made between the alarm terminal of the blow fuse and the fuse clip alarm terminal The assembly alarm terminal is shaped in a manner to capture the extended fuse alarm terminals and to allow for variations in the pressures applied by the fuse alarm terminal.

Specific details of the fuse clip assembly will now be described by way of example and with reference to the accompanying drawings, in which:Figure 1 shows a line terminal; Figure 2 shows the line terminal of Figure 1 viewed from one open side of the clip; Figure 3 shows an alarm terminal; Figure 4 shows a load terminal; Figure 5 shows an alarm assembly for use when only visual alarms are necessary; and Figure 6 shows an alarm assembly for use when both visual and electrical alarms are required.

As shown in Figures 1 and 2 a fuse clip to be used as a line terminal 10 is bent in the form of a U with the sides 18 and 19 of the U formed to accept a tubular type fuse, such as the type of fuse 41 shown in Figure 5 The fuse clip side portions 18 and 19 extend from a centre or lower portion 9 of the U and are formed with an outwardly curved section between points 15 and 16 to accept the inserted fuse The sides of the clips at positions 15 and 16 supply inward pressure on the electrical terminals 43 and 42 of an inserted fuse to hold the fuse in position and for proper electrical contact This inward pressure is created by the bending of the clip at points 14 In order to control the amount of the inward pressure, and thus control the insertion and extraction forces of the fuse, 1 581 398 points 14 are coined as depicted more clearly in Figure 2 so as to remove some material from the cross section of the clip.

In this manner a unitary piece of material can be used both for the clip and for wire wrap leg 11, so that the wire wrap leg will meet the physical dimensions for proper electrical contact to the wire which is wrapped around the leg in the manner shown in Figure 5.

Fuse clip 10 is shown having locking tab 13 constructed along wire wrap leg 11 so that when the wire wrap leg is inserted through a hole in a mounting board, as shown in Figure 6, the clip locks in place.

Short leg 12, with locking tab 13, is used to provide mechanical stability for mounting purposes.

Slots 17 in side portions 18 and 19 form an inward detent and serve to hold an inserted fuse in position and to prevent the fuse from moving longitudinally backward or forward.

This aspect will be discussed in more detail hereinafter Dimension a is typically 0 76 mm while dimension b is typically 1 52 mm.

As shown in Figure 3 the alarm terminal also has two legs 21 and 22 each with locking tabs 23 Leg 21 is the wire wrap leg while leg 22 is used for positional support.

The upper portion of the alarm terminal is shaped with an inward or concave curve so that when an alarm terminal is thrust thereagainst the alarm terminal will remain within the area defined by the side portions 25 and 26 The top of the terminal is curved slightly inward to prevent a captured fuse alarm terminal from moving upward.

As shown in Figure 4, the load terminal is designed similar to the line terminal of Figure 1 except that a forward thrust spring 37 is added to apply forward pressure on an inserted fuse.

As shown in Figure 5, fuse 41 has a rear electrical contact 42, a forward electrical contact 43, and an alarm electrical contact 44 While the fuse remains unblown, spring remains compressed and the forward edge of contact 44 remains about 7 62 mm from the leading edge of terminal 43 When the fuse element is blown the alarm terminal becomes free to move along the longitudinal axis and spring 45 causes alarm contact 44 to become extended at least 5 1 mm further.

Mounting board 40 is provided when only a visual indication is desired of the status of the fuse This visual indication is available since the fuse carries visual indicator 46 which also moves forward when the fuse is blown Thus, when the fuse assembly is arranged as shown in Figure 5 with a pair of fuse clips inserted in the appropriate holes of board 40, visual indicator 46 would not be visible through slot 47 However, when the fuse becomes blown, visual indicator 46 moves forward and passes through slot 47.

Two fuse clips are used to hold each fuse and are mounted on board 40 along the longitudinal axis of the fuse in a position relative to each other such that one fuse clip contacts electrical terminal 43 of the fuse, while the other of the pair of fuse clips contacts electrical terminal 42 of the same fuse Slot 17 in the forward fuse clip prevents the inserted fuse from moving forward, while slot 17 in the rearmost fuse clip prevents the inserted fuse from moving backward Note that both of these fuse clips are identical to each other, but that the rearmost clip is mounted on the board in a reverse manner from the forwardmost clip so that slots 17 may be properly located with respect to the inserted fuse.

Turning now to Figure 6, an assembly is shown having fuses inserted at positions 51, 52, 53, 54, 55 and 56 The fuse at position 51 is shown in the blown condition while the other fuses are shown in the unblown condition Terminal 30 is shown applying forward pressure on the inserted fuse while at the same time making electrical contact therewith As discussed, terminal 30 is a load terminal Terminal 10 is shown making contact with fuse terminal 43 and slot 17 prevents the fuse from moving forward toward alarm terminal 20 Thus, electrical contact with leg 11 of clip 10 and the application of electrical current thereto will result in the flowing of electrical current to the apparatus to be protected via leg 31 of clip 30, assuming the unblown condition of the inserted fuse Under such a condition, alarm contact 44 does not make electrical contact with alarm terminal 20 When an overload occurs the fuse element opens electrically isolating leg 31 from leg 11 At such a time fuse alarm contact 44 becomes extended under pressure from spring 45 and makes electrical contact with alarm terminal thereby completing an electrical connection to the alarm circuit Because of the shape of the alarm terminal, fuse alarm contact 44 is forced downward and is captured within the concave section of clip 20 thereby ensuring proper electrical contact.

Since the fuse is being restrained from moving rearward by the operation of spring 37 of clip 30, the force applied by spring 45 is sufficient to allow for proper electrical contact even in the presence of oxidation or dirt.

It will be appreciated that the fuse clip assembly that has been described is given by way of example only, and may include various modifications without departing from the scope of the invention.

Claims

WHAT WE CLAIM IS:-

1 A fuse clip assembly for use with tubular alarm type fuses comprising first and second fuse clips which are spaced apart and adapted to mate with and apply spring force 1 581 398 to a corresponding terminal of an inserted fuse, the first and second fuse clips having means for restricting longitudinal movement of an inserted fuse, means being provided for receiving an alarm indicator of an inserted fuse for affording an indication when the said alarm indicator is extended to an alarm condition.

2 An assembly as claimed in claim 1, comprising a mounting board on which said fuse clips are mounted, said mounting board having an upturned edge with a slot therein, said slot being in longitudinal alignment with said first and second fuse clips and adapted to receive a visual alarm indicator of an inserted fuse to afford a visual indication when said indicator is extended to an alarm condition.

3 An assembly as claimed in claim 1, comprising a mounting board on which said fuse clips are mounted, and in which the means for receiving an alarm indicator takes the form of an alarm terminal which is spaced apart in longitudinal alignment with said first and second fuse clips to receive the alarm indicator of an inserted fuse when said indicator is extended to an alarm condition.

4 An assembly as claimed in claim 3, in which the alarm terminal is provided with a slot which is adapted to receive a visual alarm indicator of an inserted fuse to afford a visual indication when said indicator is extended to an alarm condition.

5 An assembly as claimed in claim 4, in which the area around the slot of said alarm terminal is curved towards said fuse clips for retaining the extended alarm indicator of an inserted fuse.

6 An assembly as claimed in any of claims 3 to 5, in which the alarm terminal is formed of conducting material which makes electrical contact with the alarm indicator of an inserted fuse to afford an electrical indication when said alarm indicator is extended to an alarm condition.

7 An assembly as claimed in claim 6, in which the first and second fuse clips and the alarm terminal are each of unitary construction.

8 An assembly as claimed in claim 6 or claim 7, in which the first and second fuse clips and the alarm terminal each include a wire wrap leg.

9 An assembly as claimed in claim 8, in which each wire wrap leg includes a locking tab for retaining the associated clip or terminal against the mounting board.

An assembly as claimed in claim 9, in which the first and second fuse clips and the alarm terminal are each provided with a second leg having a locking tab thereon for retaining the associated clip or terminal against the mounting board.

11 An assembly as claimed in any preceding claim in which the means for restricting longitudinal movement of an inserted fuse in said first and second fuse clips takes the form of indents in said first and second clips 70 12 An assembly as claimed in any of claims 1 to 10, in which the means for restricting longitudinal movement of an inserted fuse in said first and second fuse clips takes the form of an indent in the one 75 of said fuse clips nearest the alarm indicator of an inserted fuse and a spring on the other of the said fuse clips for urging an inserted fuse longitudinally toward said one of said fuse clips 80 13 A fuse clip assembly substantially as hereinbefore described with reference to the accompanying drawings.

B.R LAWRENCE, Chartered Patent Agent, Western Electric Company Inc, Mornington Road, Woodford Green, Essex.

Agent for the Applicants.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.