EP1194943A1

EP1194943A1 - Fuse-holder clip and fuse-holder equipped with same

Info

Publication number: EP1194943A1
Application number: EP00951610A
Authority: EP
Inventors: Olivier Soumillon; Dominique Fiorini; Alain Morel
Original assignee: Ferraz Shawmut SAS
Current assignee: Ferraz Shawmut SAS
Priority date: 1999-06-17
Filing date: 2000-06-19
Publication date: 2002-04-10
Anticipated expiration: 2020-06-19
Also published as: JP2003502816A; PT1194943E; EP1194943B1; AU6449400A; FR2795229A1; FR2795229B1; DE60002873T2; ATE241212T1; US6692315B1; CA2374184A1; NO20015727D0; DE60002873D1; WO2000079555A1; ES2198338T3; DK1194943T3; NO320199B1; JP4398128B2; MXPA01013050A; CA2374184C; NO20015727L

Abstract

A fuse-holder clip including two lugs designed to define a space for receiving a fuse cartridge with circular cross-section. The lugs are folded along lines parallel to a central axis of the cartridge when the cartridge is placed in the clip such that each lug forms two electrical and mechanical lines of contact for engaging and supporting the cartridge with the two lines being globally parallel to the axis.

Description

JAW FOR FUSE HOLDER AND FUSE HOLDER EQUIPPED

OF SUCH A JAW

The invention relates to a jaw for a fuse holder and to a fuse holder equipped with at least one such jaw.

In the field of protection of electrical installations, it is known to use so-called cylindrical fuse cartridges, that is to say of which the two terminals or capsules are cylindrical, these terminals or capsules being intended to be received in jaws , themselves connected to power lines. The jaws of known devices include rounded parts intended to generally fit part of the circumference of the cylindrical capsule of a fuse. The contact between the jaws and the capsule is thus surface.

Furthermore, to resist a repulsive force created during an overcurrent, between the capsule of a fuse and the jaw in which it is received, the standards provide that the pressing or pressing force of a jaw on a fuse capsule must be of the order of several tens of Newton. For example, in the case of a fuse whose terminals have a diameter of 27 mm, the pressing force must be greater than or equal to 45 Newton. If such a force is useful when the fuse is in place in the jaw, it opposes the installation and extraction of the fuse from the jaw, so that the efforts that an operator must exert on these occasions are intense to the point that false maneuvers can be generated. Thus, it is not uncommon that when extracting a fuse from a known jaw, the effort to be exerted, which must overcome the friction generated at the contact surfaces, is so great that it induces a violent tearing of the fuse which "blows" from its housing in the fuse holder and falls to the ground. In addition, in known devices, the contacts between the cylindrical capsule of a fuse and the two legs of a jaw can be concentrated in two zones distributed on either side of the capsule, so that the dimensioning jaws must be provided considering that the breakdown current is divided in two at each jaw. This imposes the constitution of thick, therefore rigid jaws, and induces additional difficulties when installing or removing a fuse.

In the devices of the prior art, it is common to plan to operate several fuses in parallel, a rocker being provided for this operation. Given the significant efforts that must be exerted on the fuses during these maneuvers, the rocker must be able to withstand a very significant effort which leads to its over-sizing, which all the more increases the cost price of a fuse holder. .

It is to these drawbacks that the invention more particularly intends to remedy, by proposing a jaw of the aforementioned type in which a fuse capsule with circular section is effectively maintained and which allows easy insertion and extraction of such a capsule.

In this spirit, the invention relates to a jaw for a fuse holder comprising two tabs intended to define between them a space for receiving a fuse capsule with circular section, characterized in that these tabs are bent in directions parallel to a central axis of the capsule in place in the jaw, so that they each form two lines of electrical contact and mechanical support on the radial surface of this capsule, these two lines being generally parallel to this axis.

Thanks to the invention, the contact between each of the legs of the jaw and the capsule of a fuse is exerted in two lines, so that the frictional forces which must be overcome during the establishment or the fuse extraction is generated only between these lines and the outer radial surface of the capsule. They are therefore less important than in the case of surface contacts such as obtained with the devices of the prior art. Once the capsule is in place in the jaw, it is effectively maintained thanks to the cooperation of the four contact lines formed by the two jaws. These four contact lines also result in a division into four of the WO 00/79555 PCTYFROO / 01690

3 breakdown current, or even three in the event of a geometric imperfection resulting in the capsule being pressed on three of the four contact lines formed by the two jaws. The maximum current flowing in each of the contact zones is thus equal to a quarter or a third of the fuse blowing current, which makes it possible to electrically size the jaws as a function of this value, and not as a function of half the current breakdown as in the devices of the prior art. The invention also makes it possible to appropriately size the rockers provided for the joint operation of several fuses, since the forces they have to bear are substantially less than in the devices of the prior art.

According to advantageous aspects of the invention, the jaw incorporates one or more of the following characteristics:

- The traces of the two lines of electrical contact and mechanical support in a plane perpendicular to the radial surface of the capsule are included in a sector, centered on the trace of this central axis in this plane, with an angle at the vertex less than 30 °. We can, in particular, provide that this apex angle is between 20 and 28 °, preferably of the order of 24 °. Thanks to this construction, the two electrical contact and mechanical support lines formed on each tab are relatively close to each other and the linearity of the contact can be guaranteed insofar as the external radial surface of the capsule cannot penetrate between these lines to the point of generating a surface contact.

- Each tab comprises, between the contact lines, a zone deformed towards the outside with respect to a main plane of the tab. This construction allows the two contact lines to be produced in a particularly simple manner. The deformed zone advantageously comprises two surfaces inclined relative to the main plane of each tab and one relative to the other. In this case, the angle at the top of this deformed zone, which is defined by the two inclined surfaces, is advantageously between 80 and 100 °, preferably of the order of 90 °.

- The ends of the legs are divergent by relative to a median axis of the jaw. It can be expected that the angle of divergence of these ends is between 16 and 24 °, preferably of the order of 20 °. Thanks to this arrangement, the ends of the legs form a sliding cone during the introduction of the fuse capsule into the jaw, hence a gradual effort that the operator must exert for the establishment of the capsule, this progressiveness being felt by the user as additional comfort. In addition, the flared ends assist the extraction movement of the fuse cartridge because they exert on the capsule an elastic ejection force relative to the jaw. The legs of the jaw of the invention thus work both in bending and in friction during movements of fitting and extracting the fuse. - An external retaining spring is provided for bearing on the legs of the jaw at the outwardly deformed zones, relative to a main plane of each leg, these zones being defined between the contact lines. This external spring ensures the axial clamping force of the fuse capsule when it is in place in the jaw.

The invention also relates to a fuse holder equipped with at least one jaw as described above. Such a fuse holder is easier to handle for a user while remaining reliable and of moderate cost price.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a jaw for a fuse holder and of a fuse holder in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings in which: Figure 1 is a perspective view of a jaw according to the invention;

- Figure 2 is a front view of the jaw of Figure 1 at rest;

- Figure 3 is a view similar to Figure 2 while a capsule is in a first step of introduction into the jaw; - Figure 4 is a view similar to Figure 2 while the capsule is in a second step of introduction into the jaw;

- Figure 5 is a view similar to Figure 2 while the capsule is in place in the jaw and

- Figure 6 is a partial perspective view of a fuse holder according to the invention.

The jaw 1 visible in Figures 1 to 6 comprises a base 2 extending by a tongue 3 intended to be connected to an electrical conductor 4 shown diagrammatically by an axis line and belonging to a line to be connected to a fuse 5 shown in lines mixed in Figures 1 to 5 and in solid lines in Figure 6.

The base 2 is extended by two legs 21 and 22 which extend in a direction generally perpendicular to the base 2 and define between them a space E for receiving a cylindrical capsule 6 forming one of the end terminals of the fuse 5.

X _λ denotes the axis of symmetry of the capsule 6, this axis X. being disposed in a median plane P of the space E when the capsule 6 is in place in the jaw 1, as shown in FIGS. 1 and 5. We denote by D ₆ the diameter of the capsule 6.

P ₂₁ denotes a plane generally parallel to plane P which constitutes a central plane of the tab 21 in its lower part. In the same way, we denote P ₂₂ an equivalent plan for the tab 22.

According to the invention, the tab 21 is folded towards the outside of the plane P ₂₁ with respect to the space E, around an axis A ₂₁ generally parallel to the axis X _λ in the configuration of FIGS. 1 and 5 From the axis A ₂₁ , the tab 21 forms a zone 21b deformed towards the outside with respect to the plane P ₂₁ and which is concave in the direction of the space E because it is folded, around a second axis. C ₂₁ parallel to the axis A ₂₁ , and in an opposite direction. The tab 21 is also folded along an axis D ₂₁ parallel to the axis A ₂₁ and approximately included in the plane P ₂₁ . We denote respectively 21st and 21f the surfaces defined between the axes A ₂₁ and C ₂₁ on the one hand, C ₂₁ and D ₂₁ on the other hand. The zone 21b is formed of the surfaces 21e and 21f. Beyond the line 21d, the tab 21 is extended by an end 21g folded towards the outside of the plane P ₂₁ .

We note the angle at the top of the zone 21b in the plane of Figures 2 to 5 and β the angle of inclination towards the outside of the end 21g of the tab 21, that is to say its angle of divergence from plane P.

Similarly, the tab 22 is folded around axes A ₂₂ , C ₂₂ and D ₂₂ parallel to the axes A ₂₁ , C ₂₁ and D ₂₁ and comprises two surfaces 22e and 22_f extending outside the plane P ₂₂ relative to the space E and defining a zone 22b deformed towards the outside, between the axes A ₂₂ and D ₂₂ . As before, the end 22g of the tab 22 is folded outwards relative to the plane P ₂₂ .

As can be seen more particularly from FIG. 5, when the capsule 6 is in place in the jaw 1, it is formed, on the internal surface of the lugs 21 and 22 facing the space E and respectively at the axes A ₂₁ , D ₂₁ , A ₂₂ and D ₂₂ , four lines 21a, 21d, 22a and 22d of electrical contact and mechanical support between the lugs 21 and 22 and the external radial surface 6a of the capsule 6, these contact lines being generally parallel to the X axis _λ .

Thus, and as is more particularly apparent from FIG. 5, the elastic bearing force of the jaw 1 on the surface 6a is broken down into four elementary forces F _A21 , F _D21 , F _A22 and F _D22 , these forces being overall directed towards the X- axis.

In practice, the lines 21a and 22a are formed by the generatrices of the internal faces of the legs 21 and 22 at the axes A ₂₁ and A ₂₂ , these generatrices being defined respectively at the junction between the internal face of each leg 21 or 22 in its part 21c or 22c parallel to the plane P ₂₁ or P ₂₂ and the surface 21st or 22nd. The lines 21d and 22d are formed by the generatrices of the internal faces of the lugs 21 and 22 at the level of the axes D ₂₁ and D ₂₂ , these generatrices being defined respectively at the junction of the internal faces of the surfaces 21f _. and 21g or 22f and 22g.

In the plane of FIGS. 2 to 5, the traces of lines 21a, 22a, 21d and 22d are included in two angular sectors Δ ₂₁ and Δ _{22 of} which the angle at the top is noted γ. The angle γ is of the order of 24 °, this value giving satisfactory results over a range between 20 and 28 °.

This relatively low angle γ value corresponds to the fact that the lugs 21 and 22 are relatively slightly deformed in bending during the positioning and extraction of the capsule 6. The forces to be overcome therefore keep a relatively low value, hence a comfort of use during the installation and extraction of the fuse 5. Thanks to this arrangement, the contact lines 21a, 22a, 21d and 22d are close enough to each other so that the surface 6a of the capsule 6 is not likely to penetrate inside the zones 21b and 22b to the point that a surface contact takes place between this surface 6a and the internal surface of the zones 21b and 22b. In other words, the geometry of the legs 21 and 22 ensures a double linear contact between these legs and the capsule 6, including in the event of slight dimensional defect in the jaw 1 or the capsule 6.

Thanks to the invention, the maximum current capable of passing between the fuse 5 and the conductor 4 is divided into four at the lines 21a, 22a, 21d and 22d. In the event of a geometric defect in the capsule 6, one of the aforementioned lines may not be in contact with the surface 6a, the maintenance being however correctly ensured by virtue of the three other contact lines which define, with the capsule 6, a system isostatic. In all cases, it can be considered that the maximum current flowing on a contact line between the surface 6a and a lug 21 or 22 is at most equal to a third, or even a quarter of the fuse breakdown current, so that the thickness e of the tabs 21 and 22 can be defined as a function of this parameter.

The introduction of the capsule 6 into the jaw 2 is shown in Figures 3 and 4. At the start of the introduction, the external radial surface 6a of the jaw 6 rests against the internal surface of the ends 21g and 22g of the legs 21 and 22 The pushing force exerted by a user is represented by the arrow F ₂ and is transferred to the level of the contact zone between the surface 6a and the ends 21g and 22g, as shown feel by the arrows F ₃ . These efforts F ₃ have the effect of bending the tabs 21 and 22, as shown by the arrows F ₄ , while a friction force represented by the arrow F ₅ is generated at the contact surfaces, 6a, 21g and 22g in the configuration of Figure 3. The legs 21 and 22 therefore work both in bending and in friction. In the configuration of FIG. 4, the force F ₂ which the user must exert essentially aims at spreading the legs 21 and 22 by bending, as represented by the arrows F ₄ , because the friction force is significantly reduced due to the fact of the essentially linear contact which then takes place between the lines 21d and 22d and the surface 6a. This effort is not much greater than the effort that must be exerted in the configuration of Figure 3, even though the legs 21 and 22 are more bent.

We reach in the position of Figure 5 where the forces F _A21 , F _D21 , F _A22 and F _D22 exerted along the four lines 21a, 21ç, 22a and 22ç are directed towards the axis X _L and border the two sectors Δ ₂₁ and Δ ₂₂ of angles at the top γ in the plane of FIG. 5. The capsule 6 is then firmly immobilized, all the more so since a retaining spring 7 can be used, as shown in FIG. 6.

We note d. the distance between the lines 21a and 22a on the one hand, 21d and 22d on the other hand, in the configuration of FIG. 5. Taking into account the relatively small value of the angle γ, the distance d, is slightly less than the diameter D ₆ , which corresponds to the fact that the lugs 21 and 22 are only slightly deformed in bending during the positioning of the capsule 6. When it is necessary to extract the fuse 5, it suffices to exercise on the latter a force in the opposite direction to the force F ₂ , the contacts between the surface 6a and the lines 21a and 22a then being eliminated, so that only the linear contacts remain at the level of the lines 21d and 22d, a movement that can be generated without too much effort, so that the fuse must not be subjected to efforts or accelerations that may result in it falling outside the fuse holder. As shown in Figure 6, two jaws 1 and 1 'can be used in a fuse holder by being arranged, in opposition, at the two capsules 6 and 6' of a fuse 5. Each jaw 1 or 1 'is connected by a 3 or 3 'tab to a 4 or 4' conductor. Each jaw is associated with a spring 7 or 7 ′, in the form of a clamp, designed to exert on the legs 21 and 22 a force F ₅ of pinching the capsules 6 or 6 ′. The effort F ₅ can be relatively high, in particular so that the fuse holder complies with the standards in force, without hampering the fitting and extraction of the fuse, since this effort F ₅ is transmitted to the capsules 6 and 6 'by the linear contact obtained at lines 21a, 22a, 21d and 22d.

In the configuration of FIG. 6, the movement of insertion and extraction of the fuse 5 in the jaws 1 is a pivoting movement around a transverse axis Y, this movement being represented by the arrow F ₆ . Given the direction of this movement and to limit the contact forces, the ends 21g and 22g each include an angled edge 21h, 22h.

Claims

1. Jaw for fuse holder comprising two tabs intended to define between them a space for receiving a fuse capsule with circular section, characterized in that said tabs (21, 22) are bent in directions (A ₂₁ , C ₂₁ , D ₂₁ , A ₂₂ , C ₂₂ , D ₂₂ ) parallel to a central axis (X of said capsule (6) in place in said jaw (1), so that they each form two lines (21a, 21d , 22a, 22d) of electrical contact and mechanical support on a radial surface (6a) of said capsule, said two lines being generally parallel to said axis.

2. Jaw according to claim 1, characterized in that the traces of said two lines (21a, 21d, 22a, 22d) of electrical contact and mechanical support in a plane perpendicular to said radial surface (6a) of said capsule are included in a sector, centered on the trace of said central axis (X.) in this plane, with an apex angle (γ) less than 30 °.

3. Jaw according to claim 2, characterized in that said apex angle (γ) is between 20 and 28 °, preferably of the order of 24 °.

4. Jaw according to one of the preceding claims, characterized in that each tab (21, 22) comprises, between said contact lines (21a, 21d, 22a, 22d), an area (21b, 22b) deformed towards the outside with respect to a main plane (P ₂₁ , P ₂₂ ) of said tab.

5. Jaw according to claim 4, characterized in that said deformed zone (21b, 22b) comprises two surfaces

(21st, 21f _. , 22nd, 22f) inclined with respect to said plane (P ₂₁ , P ₂₂ ) and one with respect to the other.

6. Jaw according to claim 5, characterized in that the apex angle (α) of said deformed area (21b, 22b) defined by said two inclined surfaces (21e, 21f, 22e, 22f) is between 80 and 100 °, preferably of the order of 90 °.

7. Jaw according to one of the preceding claims, characterized in that the ends (21g, 22g) of said legs (21, 22) are divergent with respect to a median plane (P) of said jaw (1).

8. Jaw according to claim 7, characterized in that the divergence angle (.) Of said ends (21g, 22g) is between 16 and 24 °, preferably of the order of 20 °.

9. Jaw according to one of the preceding claims, characterized in that it is associated with an external spring (7) for holding which is supported on said tabs (21, 22), at the level of zones (21b, 22b) deformed outwards, with respect to a main plane (P ₂₁ , P ₂₂ ) of each tab, said zones being defined between said contact lines (21a, 21d, 22a, 22d).

10. Fuse holder equipped with at least one jaw (1) according to one of the preceding claims.