EP0339846A2

EP0339846A2 - Fuse box

Info

Publication number: EP0339846A2
Application number: EP89303763A
Authority: EP
Inventors: Melvyn Adams
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1988-04-23
Filing date: 1989-04-17
Publication date: 1989-11-02
Also published as: GB8809663D0; EP0339846A3

Abstract

A fuse box comprising a housing (11) defining a row of equally spaced, parallel, fuse clip receiving passages (13), and, a pair of fuse clip units (18a 18b) the fuse clips (19) of which are received within respective passages (13) of said row, each of said fuse clip units (18) comprising a busbar (20) and a plurality of integral, spaced fuse clips (19), the spacing between adjacent fuse clips (19) of each fuse clip unit (18) being double the spacing between adjacent passages (15) of the row, and, said fuse clip units (18) being staggered longitudinally relative to one another by a distance equal to the spacing beween adjacent passages (13) such that the first fuse clip of the first unit (18a) is engaged in the first passage of said row, the second clip of the first unit (18a) is engaged in the third passage of the row, the first clip of the other unit (18b) is engaged in the second passage of the row, the second clip of the other unit (18b) is engaged in the fourth passage of the row, and so on.

Description

This invention relates to a fuse box for use primarily, but not exclusively, in a vehicle electrical system.
In our British Patent No. 2123626 there is disclosed a fuse box including a fuse clip unit wherein a busbar is integral with, and electrically interconnects, a plurality of spaced parallel fuse clips. The fuse clip unit is formed from brass sheet by stamping and folding such that the busbar, the fuse clips, and means for gripping and making electrical connection to one or more electrical connecting leads, are integral with one another.
The fuse clip unit disclosed in British Patent No. 2123626 is suitable for many applications, but presents problems where a close positioning of adjacent parallel fuse clips is required. It will be recognised that since the clips are integrally formed by stamping and folding sheet material, then the developed width (the unfolded width) of each clip determines the minimum spacing between clips along the length of the busbar with which the clips are integral. For example, where the developed width of each clip is 15mm and the clips, in their developed form, are symmetrical about centre lines extending at right angles to the length of the integral busbar, then the minimum spacing of clips (measured from centre line to centre line) is 15mm.
In an attempt to overcome this problem it has previously been proposed to produce a fuse clip unit where the fuse clips are at their minimum spacing, and then to fold or otherwise deform the busbar between adjacent clips so as to reduce the spacing between clips. This solution is disadvantageous in that additional manufacturing steps are necessary to shorten the busbar between clips, and in that the shortening operation itself risks damage to the fuse clip unit so increasing the failure rate. Moreover, the mechanical working of the busbar inherent in the shortening operation, may affect the electrical properties of the busbar, and of course the shortened busbar occupies greater space in the fuse box, in the direction in which the busbar is deformed, and thus the fuse box design must accommodate this increase in busbar dimension.
It is an object of the present invention to provide a fuse box wherein adjacent fuse clips can be positioned at a spacing less than the minimum spacing of the clips along their integral busbar.
In accordance with the present invention there is provided a fuse box comprising a housing defining a row of equally spaced, parallel, fuse clip receiving passages, and, a pair of fuse clip units the fuse clips of which are received within respective passages of said row, each of said fuse clip units comprising a busbar and a plurality of integral, spaced fuse clips, the spacing between adjacent fuse clips of each fuse clip unit being double the spacing between adjacent passages of the row, and, said fuse clip units being staggered longitudinally relative to one another by a distance equal to the spacing between adjacent passages such that the first fuse clip of the first unit is engaged in the first passage of said row, the second clip of the first unit is engaged in the third passage of the row, the first clip of the other unit is engaged in the second passage of the row, the second clip of the other unit is engaged in the fourth passage of the row, and so on.
Conveniently each fuse clip of a unit protrudes to one side of the plane of the busbar of the unit and said first and second units are arranged with their one sides, mutually presented.
Desirably the fuse box includes an electrically insulating member retained within the box in a position preventing withdrawal of said clips from said passages and extending between the busbars of the first and second units to maintain a spacing therebetween.
Alternatively said first and second units are arranged with their one sides facing in the same direction and their busbars in contact.
Preferably at least two of said passages incorporate clip retaining means whereby the respective clip and thereby the other clips integral therewith are retained in position, one of said at least two passages receiving a clip of the first unit and the other of said at least two passages receiving a clip of the other unit.
One example of the invention is illustrated in the accompanying drawings wherein:

Figure 1 is a diagrammatic plan view of one face of a fuse box with the fuse clips thereof omitted,
Figure 2 is a view similar to Figure 1 of the opposite face of the fuse box,
Figures 3 and 4 are sectional views on the lines 3-3 and 4-4 respectively in Figure 2,
Figure 5 is a diagrammatic view illustrating the engagement of a pair of fuse clip units with the fuse box illustrated in Figures 1 to 4,
Figure 6 is a diagrammatic, partly exploded, view of the arrangement of the fuse clip units of Figure 5, and
Figure 7 is a side elevational view, partly in section, and to a greatly increased scale, of a fuse clip and its associated busbar.

Referring to the drawings, the fuse box comprises a moulded synthetic resin body 11 incorporating a plurality of parallel passages 12, 13. The passages 12, 13 are arranged in two adjacent, parallel rows 12a, 13a, the passages extending at right angles to their respective row and each passage 12 of the row 12a being aligned in a direction transverse to the row with a corresponding passage 13 of the row 13a.
An elongate, shallow, channel 14 is defined in one face of the body 11 and each of the passages 12, 13 opens, at one end, into the base of the channel 14. The width and length of the channel 14 is such as to accommodate the rows 12a, 13a and the side walls of the channel 14 include integral, laterally extending, mutually presented projections 15 which divide the channel into fuse receiving sections. Each section contains the end of a passage 12, and the end of the corresponding passage 13.
At their opposite ends the passages 12, 13 open into a recess 16 within the body 11.
In use the recess 16 will receive one or more printed circuit boards, and the channel 14 will be closed by a detachable cover. A fuse clip 19 of the kind illustrated in Figure 7 will be received in each of the passages 12, 13 such that a fuse receiving portion of the clip will lie immediately beneath the channel 14.
As is clear from Figures 5, 6 and 7 the fuse clips 19 are manufactured as parts of a respective fuse clip unit 18, each unit 18 including a busbar 20 with which the clips 19 of the unit are integral.
Each fuse clip unit 18 is formed by stamping and bending operations performed on an elongate strip of plain or tinned brass. Each clip 19 has two distinct, but integral portions, a fuse receiving portion 21 and a lead connection portion 22. Each clip is integral with its respective busbar 20 at the end of the portion 22 remote from the portion 21. Each portion 22 is of U-shaped cross-section and includes two pairs of deformable tags 23, 24 crimpable respectively to engage a bared length of the core, and the insulating sheath, of an electrically conductive lead.
The fuse receiving portion 21 of each fuse clip 19 comprises a pair of elongate, transversely spaced, resilient arms 25 extending outwardly in the direction of the length of the clip. Part-way along their length the arms 25 are bent back upon themselves so that the end regions of the arms 25 lie close together, or even in facial contact, and extend back towards the portion 22 of the clip between their respective root portions. It will be recognised therefore that the closely adjacent portions 25a of the arms 25 define a pair of substantially planar regions urged, by the inherent resilience of the arms 25, towards facial contact with one another. A flat blade-like terminal of a planar fuse introduced between the portions 25a will be gripped thereby, and there will be established a good electrical connection over a large surface area.
It will be recognised that during the manufacture of a clip unit 18 the minimum spacing of clips 19 along the length of the busbar 20 is determined by the developed (unfolded) width of the clips 19. Thus there is a minimum spacing of clips 19 on the busbar 20 and it is not possible to achieve a closer spacing without deforming the busbar between the clips 19.
The clips 19 engaged in the passages 12 have been detached from their respective busbar 20, and thus are electrically isolated from one another. In practice these clips will be carried by a printed circuit board, and will be electrically connected to respective conductors of the printed circuit board. However, the clips 19 engaged in the passages 13 are intended all to be electrically connected to a power supply terminal, and thus can be electrically interconnected. It is convenient therefore to leave these clips 19 attached to their respective busbars 18. However, as is apparent from Figures 5 and 6 the spacing between adjacent passages 13 is less than the minimum spacing which can be achieved between adjacent clips 19 of the same clip unit 18. Thus it is impossible for adjacent clips 19 of a unit 18 to be engaged in adjacent passages 13 of the body 11 and in order to overcome this problem the unit 18 is manufactured with a clip spacing which is double the spacing between adjacent passages 13. Thereafter a pair of units 18 are positioned in staggered relationship to one another and the clips 19 of the two units 18 are introduced into the passages 13. In Figures 5 and 6 the two units are indicated at 18a and 18b respectively, and the passages 13 are numbered 1 to 10 respectively. It can be seen therefore that the clip 19 engaged in the first of passages 13 is the first clip of unit 18a whereas the clip engaged in the second of passages 13 is the first clip of unit 18b. The clip engaged in the third passage is the second clip of unit 18a and the clip engaged in the fourth passage is the second clip of unit 18b. The relationship is clearly shown in Figure 6 where each of the clips is identified by the number of the passage receiving the clip.
The structure of each clip 19 is upstanding to one side of the plane of its respective busbar 20. It can be seen in Figure 5 that the units 18a and 18b are oppositely orientated in that the unit 18a is introduced to its respective passages 13 with the busbar thereof adjacent the passages 12 whereas the unit 18b is introduced into its passages 13 with the respective busbar remote from the passages 12. Such opposite orientation of the units 18a, 18b results in there being no physical contact between the units and thus where the clips of the units 18a and 18b are to be electrically connected to the power supply terminal (for example a terminal of the vehicle battery) then individual connections to each unit are needed. It will be recognised therefore that if desired there could be different connections to the two units 18a, 18b. For example the unit 18a might be directly connected to the power supply terminal while the unit 18b is connected to the power supply terminal through a switch (for example the vehicle ignition switch). In such an arrangement alternate fuse clips in the row would be permanently connected to the power supply terminal and the others would be switched by ignition switch. Although not shown in the drawings an internal moulded synthetic resin cover member is provided which firs within recess 16 and has an integral elongate rib overlying the ends of the passage 13. The rib prevents withdrawal of the clips from the passages 13 and its thickness is such that it extends between the busbars of the units 18a and 18b to hold them in spaced relationship.
It should be recognised however that while the opposite orientation of the units 18a, 18b is preferred it is not essential and if desired the two units 18a, 18b can be similarly orientated such that their busbars lie in facial contact. The cover mentioned above can still be incorporated, in rib being dimensioned again to prevent withdrawal of the clips and also to trap the busbars of the units in facial contact. There is sufficient compliance between the clips 19 and the walls of their respective passages 13 to permit the corresponding slight misalignment of adjacent clips 19.
Since the clips 19 of each unit 18 are interconnected by the respective busbar 20 only a single electrical connecting lead 26 is required for each unit 18. Thus a connecting lead 26 will have an end region of its core bared and the lead will be physically and electrically secured to one of the clips 19 of the unit 18 by crimping the tags 23 around the bared core and the tags 24 around the sheath of the lead. However, since each clip 19 of each unit 18 has crimpable tags 23, 24 leads can be connected to other clips of a unit if desired. For example, it may be desired to make electrical connection to a unit 18 by way of two or more leads to provide a required electrical current capacity.
As mentioned previously, when the clips 19 are received in their respective passages 12, 13 the fuse receiving portions (the arms 25) lie immediately beneath the channel 14. A clip 19 of one of the two units 18 will be positioned in a passage 13 and an equivalent clip secured to a conductive track of the printed circuit board will be positioned in the adjacent passage 12. A planar fuse having co-planar, spaced, blade terminals will be introduced into the channel 14 such that the blade terminals extend downwardly into the passages 12 and 13 respectively and thus the blade terminals of the fuse will be electrically connected through the clip of the passage 13 to the lead 26, and through the clip of the passage 12 to the appropriate conductor of the printed circuit board.
In order to retain the clips 19 in position in their passages 12, 13 certain of the passages are provided with integral resilient latches 27. Figures 1 and 2 show that only two of the passages 12 are provided with latches 27 and this is because, as mentioned previously, the clips engaged in the passages 12 are all carried by a common printed circuit board. Thus once the printed circuit board is secured to the body 11 the respective clips will be held in position in the passages 12 by the printed circuit board. Thus the latches 27 of the passages 12 serve simply to hold the assembly of clips 19 and printed circuit board in position prior to securing the printed circuit board to the body. Four of the passages 13 incorporate latches 27, two of the four passages 13 having their latches positioned to co-operate with the unit 18a and the other two having their latches positioned to co-operate with the unit 18b (based upon the assumption that the units 18a and 18b will be oppositely orientated as illustrated in Figure 5, it being understood that all four latches 27 of the passages 13 would be similarly orientated when the units 18a, 18b are to be positioned with their busbars in facial contact).
Each latch 27, irrespective of its orientation, is defined by an elongate flexible finger integral with the wall of its respective passage, and having a barbed lateral projection 28 at its free end. During introduction of a clip 19 into the respective passage engagement of the clip with the barbed projection 28 deflects the finger laterally until the projection 28 can snap into an aperture 29 provided in each clip 19 thereby locking the respective clip 19 in the respective passage. It will be recognised that locking of one clip 19 of a unit 18 in its respective passage is sufficient to lock all of the other clips in their passages but it is desirable to provide two latches 27 for each unit 18 to improve security. It will be understood that if units 18a and 18b are not to be oppositely orientated then the latches 27 of the passages 13 will be identically orientated.

Claims

1. A fuse box comprising a housing (11) defining a row of equally spaced, parallel, fuse clip receiving passages (13), and a respective fuse clip (19) housed within each of the passages (13) of said row, the fuse box being characterized in that said fuse clips (19) are parts of a pair of fuse clip units (18a, 18b), each of said fuse clip units comprising a busbar (20), and a plurality of integral, spaced fuse clips (19), the spacing between adjacent fuse clips (19) of each fuse clip unit (18) being double the spacing between adjacent passages (13) of the row, and, said fuse clip units (18) being staggered longitudinally relative to one another by a distance equal to the spacing between adjacent passages (13) such that a first fuse clip of the first unit (18a) is engaged in a first passage of said row, the second clip of the first unit (18a) is engaged in the third passage of the row, a first clip of the other unit (18b) is engaged in the second passage of the row, the second clip of the other unit (18b) is engaged in the fourth passage of the row, and so on.

2. A fuse box as claimed in claim 1 characterized in that each fuse clip (19) of a unit (18) protrudes to one side of the plane of the busbar (20) of the unit and said first and second units are arranged with their one sides mutually presented.

3. A fuse box as claimed in claim 2 characterized by an electrically insulating member retained within a position preventing withdrawal of the clis (19) from said passages (13) and oxtending between the busbars (20) of the first and second units (18a, 18b) to maintain a spacing therebetween.

4. A fuse box as claimed in claim 1 characterized in tha each fuse clip (19) of a unit (18) protrudes to one side of the plane of the busbar (20) thereof and the units (18a, 18b) are positioned within their busbars (20) in facial contact.

5. A fuse box as claimed in any one of claims 1 to 4 characterized in that at least two of said passages (13) incorporate clip retaining means (27) whereby the respective clip (19) and thereby the other clips integral therewith are retained in position, one of said at least two passages receiving a clip (19) of the first unit (18) and the other of said at least two passages receiving a clip (19) of the other unit (18).