EP0133094A1 - Elastic removable connection socket for an electric terminal contact - Google Patents

Abstract

1. An electrical terminal connector comprising at least one tubular portion being suitable for being removably fixed by elastic deformation to a cylindrical terminal (10) and being formed by a blank (1) of flat sheet metal substantially rectangular, a tab (5) being cut out in one of the sides of said blank (1), characterized in that : - said tubular portion is formed by spirally winding said blank (1), said side of said blank (1) including said tab (5) being disposed on said free face of said tubular portion ; in that - said tab (5) is folded radially, through a window (6) cut out through the adjacent turns of said tubular portion and is standing proud from the contact face of said tubular part ; and in that - the width of said window (6) enables the circonferential moving of said tab (5) between a first position in which said turns are close to one another and a second position in which said turns are not so close as in said first position, so that the contact with said terminal (10) is provided in the section of said tab (5) in the one of said first and second positions causing the most stressed state of said spiral winding.

Description

The present invention relates to a removable elastic connection terminal for an electrical contact terminal. The invention is aimed at both female lugs to be engaged on male terminals and male lugs, which can be engaged in hollow tubular terminals. The invention applies in particular but not exclusively to the lugs for spark plugs of internal combustion engines.

One of the properties sought for such terminals is good electrical contact: it is therefore sought to have a contact member applied elastically with as great a force as possible. The terminal must therefore be deformable. A second sought-after property is the limitation of the deformation of the terminal, during installation, or removal. Thus, for example, the plugs of automobile spark plugs are sometimes extracted obliquely with respect to the axis of the terminal (for example due to difficulties of access), which can cause permanent deformation of the terminal by exceeding the Elastic limit. The terminal is no longer usable. This is what one seeks to avoid by providing the terminal with a locking means limiting its deformation. Finally, the terminal must be snap-on. After being pushed in with reasonable force, it must remain snapped onto the terminal.

Finally, we look at the manufacturing economy. If possible, the terminal will be in one piece. This is also favorable to its reliability.

It is known to manufacture male-female or female-male connections for high contact pressure forces, but they involved on both sides, that is to say very limited deformation aptitudes and therefore tight reciprocal tolerances for the dimensions. and precise handling, either a mechanism or bulky shapes, in lyre for example, or finally connections comprising several parts, one for tightening, the other for making contact or finally another part for locking. The object of the invention is to produce a terminal allowing a large clamping force, with a capacity for significant deformation, for example three to five times greater than that which is commonly accepted for this kind of connection element.

According to the present invention, an electrical connection lug comprising at least one tubular contact part adapted to be removably elastically fixed on a terminal, this part being formed by winding a blank of substantially rectangular flat sheet metal with overlapping of the edges so as to form a spiral winding, is remarkable in particular in that a tab is cut in the vicinity of one end of the spiral and folded towards the contact face, or towards the terminal through a window, cut in the turns adjacent, the length of the tab being sufficient to project on the other face of the tube formed by the spiral so as to be able to come into contact with the terminal, the window being wide enough to allow the tab to move towards the either side when the spiral tightens or loosens.

The term spiral should not be retained here with a particular geometric meaning. It means that an edge of the sheet blank has passed over the opposite edge, for example in the case where the tubular part has only one turn. It is therefore possible that the largest part of the section has the shape of a circle, the part of the section forming the edge being placed over the other representing a deviation from the circular section.

When it has a terminal engaged on a central terminal, generally full, such as a spark plug terminal, the tab is formed in the outer edge of the coil, and is folded inward. In the case of a hollow terminal, the terminal having to engage inside, the tab is formed on the inside edge of the coil, and is folded outwards.

The end of the tab folded back through the spiral forms both the electrical contact element, the locking member limiting elastic deformation, of the terminal itself, and the latching or clip-on member. ge coming to engage in a circular groove of the terminal. When the terminal deforms under an effort, the spiral tightens or loosens as the case may be, and the elastic deformation is limited by the arrival in abutment of the folded tab against an edge of the window.

To ensure a sufficiently flexible electrical contact, the end of the tab must protrude substantially out of the window. According to the invention, the projecting projection of the folded tab is greater than or equal to the thickness of the metal blank constituting the pod.

To facilitate the installation of the terminal on the terminal, the tab is formed with at least one insertion ramp making an angle of the order of 20 to 40 °, cut in the blank of the tab or formed by folding this one. The terminal can also advantageously include a latching ramp, opposite the previous one and forming an angle of 90 ° maximum, preferably 40 to 60 °.

We will see in the following description that the terminal behaves like a spiral spring of which only a part is brought into play during elastic deformations. The proportion of the length of the spiral involved depends on the number of turns it comprises, and this length varies step by step (discreetly) depending on the number of turns n + 1/2.

The window pierced at. through the metal decreases the elastic force of the terminal, also, according to another characteristic of the present invention, the height of the window in the direction of the axis of the terminal is less than or equal to one third of the length of the terminal when the spiral comprises more than one and a half turns, and less than or equal to three-quarters of the height of the blank when the spiral comprises less than one and a half turns. Indeed, as discussed below him, the ^the impact of the opening of the window is not the same in both cases.

To allow the elastic deformation of the terminal, when the spiral tightens or loosens, the tab engaged in the window must be able to move towards an edge of this one or towards the opposite edge. According to the invention, the width of the window, in the direction perpendicular to the axis of the terminal, is equal to the sum of the circumferential width of the tab and at least three times the possible radial displacement of the latter. , that is to say the projection of the tab out of the window.

Other characteristics of the invention will appear during the description which follows, given by way of nonlimiting example, with reference to the attached drawings and which will make it clear how the invention can be implemented.

• - la figure 1 est une vue en plan d'un flan de tôle souple,découpée pour foncer par enroulement une cosse conforme à l'invention;
• - la figure 2 est une vue en coupe perpendiculaire à l'axe d'une cosse selon l'invention, formée par enroulement du flan de la figure 1, représentant en trait interrompu la cosse à l'état libre, détendue et en trait plein, la cosse déformée élastiquement après mise en place sur une horne;
• - la figure 3, est une vue en coupe longitudinale de la cosse de la figure 2, suivant la ligne III-III de la figure 2;
• - la figure 4 est une vue en coupe perpendiculaire à l'axe d'une autre cosse selon l'invention, à l'état déformé par mise en place sur une borne;
• - les figures 5 et 6 sont des vues en plan de flans en tôle souple découpée pour former des cosses selon l'in-
• . vention;
• - les figures 7 et 8 sont des vues en coupe, respectivement perpendiculaires à l'axe et axiales de la cosse formée avec le flan de la figure 5; et
• - les figures 9 et 10 sont des vues analogues aux figures 7 et 8, mais pour le flan de la figure 6.

In the drawings,

• - Figure 1 is a plan view of a flexible sheet blank cut to darken by winding a terminal according to the invention;
• - Figure 2 is a sectional view perpendicular to the axis of a terminal according to the invention, formed by winding the blank of Figure 1, showing in broken lines the terminal in the free state, relaxed and in solid line , the terminal resiliently deformed after place on a horne;
• - Figure 3, is a longitudinal sectional view of the terminal of Figure 2, along the line III-III of Figure 2;
• - Figure 4 is a sectional view perpendicular to the axis of another terminal according to the invention, in the deformed state by positioning on a terminal;
• FIGS. 5 and 6 are plan views of blanks of flexible sheet metal cut out to form lugs according to the invention;
• . vention;
• - Figures 7 and 8 are sectional views, respectively perpendicular to the axis and axial of the terminal formed with the blank of Figure 5; and
• - Figures 9 and 10 are views similar to Figures 7 and 8, but for the blank of Figure 6.

The blank 1 shown in Figure 1 comprises a substantially rectangular part 2, intended to form the terminal 20 according to the invention. It may further comprise a part 3 intended for fixing a cable, and a part 4 for connection between these two parts. The terminal can be used in these latter parts, for example one can solder a conductor there. At the left end is cut a tab 5, folded back so that it can pass through the window 6 when the rectangular part 2 is wound in a spiral (see FIG. 2). The wings 7, 8 adjacent to the tab 5 can be kept or eliminated. To form the terminal according to the invention, the rectangle 2 is therefore wound in a spiral, as shown in section in FIG. 2, to form a sleeve or a tube. If the tab 5 is located on the outer end of the spiral, it is folded inward (Figure 2). If the lug 15 is located on the inner end of the spiral (Figure 7) it is folded outwards. In the first case, a female lug is obtained, which can be engaged on a male terminal. In the second case, a male terminal is obtained, which can be engaged in a terminal dig.

Figure 2 shows a section perpendicular to the axis of the female terminal formed with the tab at the end of the spiral. The dotted line shows in section the profile of the terminal in the free, relaxed state, the folded tab 5 projecting clearly inside. When the terminal is engaged on a terminal 10, the tab 5 is pushed outwards and comes to take the position 5 ′ shown in solid lines in FIG. 2. The tab moves outward and, at the same time, the spiral opens, which moves the tab 5 in the window 6. This window must be wide enough to allow the free movement of the tab 5, without hampering the elastic movement, neither in one direction nor in the other. Advantageously, the window will have a width which is at least the sum of the thickness of the tab (in the circumferential direction) and three times the maximum displacement of the tab, that is to say three times the distance from which it s 'protruding inside the terminal. To ensure elastic contact with the terminal 10, the tab 5 must extend inside the terminal, by a distance equal at least to the thickness of the metal and the terminal.

If it is sought to deform the terminal as much as possible, for example by inclining it with respect to the terminal, the tab 5 abuts against the edge 6a of the window 6, and the terminal cannot increase further. The terminal cannot be deformed due to an abnormal force.

As can be easily understood, and as shown in FIG. 2, the terminal 10 is elastically clamped between the edge 5a of the tab 5 on the one hand, and the edge 9 of the rectangle 2 of the blank 1. The effort elastic, ensuring the electrical contact between the terminal and the terminal, exerted by these two points on the terminal, is developed over the length of the spiral between these two points, ie one and a half turns in the case of FIG. 2. The flexibility is therefore important and electrical contact is ensured with wide tolerances on the diameter of the terminal.

To facilitate the insertion of the terminal 20 onto the terminal 10, in the direction of the arrow F in FIG. 3, it is advantageous to provide a ramp 21 from approximately 20 to 40 ⁰ . This ramp can be obtained by suitable cutting of the blank, or by folding a metal wedge. In the case of the example shown in Figures 1 to 3, cutting is preferable. If the terminal is intended to be engaged on an automobile spark plug, the tab 5 comes to engage elastically in the groove formed on the terminal of the spark plug. To be able to extract the terminal without difficulty, it is advantageous to provide an extraction ramp 22, opposite to the ramp 21, and which may have an angle between 45 and 90 ° - 60 ° for example. In this case, an electrical contact can also be established by one or the other of the ramps 21, 22 or both, instead of the straight edge 5a. Simultaneously, the tab 5 serves as a snap finger on the terminal, when the latter has an adequate groove.

• 1) decontact électrique élastique;
• 2) de verrouillage ou blocage de la cosse pour empêcher une déformation excessive d'ouverture ou d'écrasement;
• 3) de doigt d'encliquetage.

It therefore appears from the preceding description that the tab 5 is used both:

• 1) elastic electrical contact;
• 2) locking or blocking the terminal to prevent excessive deformation of opening or crushing;
• 3) click finger.

According to the invention, a metal lug is produced in a single piece which performs the three desired functions.

Figure 4 shows in section through a plane intermediate to its axis, a terminal 41 formed by winding a blank over a little more than one turn, but less than one and a half turns. The terminal is formed by a shorter spiral and also includes a lug 49 engaged in a window 43. The terminal 45 on which the lug 41 is engaged is elastically clamped between the lug 49 and the point 44 diametrically opposite. It can be seen that, in this case, the length of spring interesting the clamping force of the terminal is half a turn of the spiral forming the terminal. A possible extension 46 of the spiral will not interest the spring force, as long as this extension does not bring the length of the spiral to one and a half turns, that is to say as long as the inner end of the spiral is not diametrically opposite the tab projecting inside the terminal. It follows that the lengths of spiral interested in the elastic force increase discreetly as a function of the length of the spiral and are 1/2, 1.5, 2.5 etc. turns, provided that the spiral has between 1 and 1.5 turns, between 1.5 and 2.5 ... etc.

It will also be noted that, in the case of FIG. 4, the part of the spiral interested in the elastic force is the part between the tab 49 and the opposite point 44, part which the window 43 does not include. In the embodiments where the spiral has a revolution and a half or more, the part of the spiral interested in the elastic force comprises the window. Therefore, in this case of FIG. 4, less than 1.5 turns, the weakening caused in the resistance of the terminal by the cutting of the window does not affect the elastic clamping force of the terminal . It is however reasonable to limit the size of the window, the edge of which nevertheless serves as a limitation to elastic deformation.

Therefore, in this case, the height of the window measured in the direction of the axis of the terminal, will preferably be less than or equal to three-quarters of the length of the terminal (dimension h in FIG. 1). But, if the spiral measures more than 1.5 turns, the window is in the spring part, and its height in this case should be less or equal to a third of the length of the terminal.

In Figure 4, the contact between the terminal and the terminal is made at two points; on the edge of the tab 49 and at the opposite point 44 where the wall of the terminal is tangent to the wall of the terminal 45. To increase the contact surface, and to increase the tightening of the terminal on the terminal, this part 44 of the section of the terminal may have a circular profile, extends as far as possible on either side of point 44, possibly 'to the edge of the terminal, in the direction of the opening 43. The section is thus circular over more than half of the periphery, which is favorable to electrical contact and tightening.

The tab 49 then participates in a minor way in the electrical contact. It always performs the role of a lock preventing the terminal from opening and the role of snap-fastening in the terminal groove.

Figures 5 to 10 show two other variants of terminals according to the invention.

The blank of Figure 5 is similar to that of Figure 1. There is shown in Figures 7 and 8 a terminal 51 produced by spiral winding of the blank of Figure 5, placing inside the end of the rectangle which carries the tab 15. A male terminal is obtained which can exert an extension force towards the outside, between the edge of the tab 15 and the outer edge 52 of the spiral. The terminal can be introduced and wedged into a tubular socket, thanks to the cut shape of the tab 15, in a similar manner to that of the tab 5 of FIG. 3.

On the blank 60 of Figure 6, the tab 61 is formed by folding in the direction perpendicular to the axis of the terminal. It follows a window 62 smaller in the direction of the height, but longer in the direction of the width. The weakening of the elastic force of the spiral is less in this case, which may be better suited to the spirals of a turn and a half and more, in cases where the window is included in the part of spiral forming a spring. The end 6la of the tab 61 is folded back to facilitate engagement and snap-fastening.

The slope of the insertion ramp can also be obtained by a false cut, that is to say a non-punching punching cut, leaving an oblique section.

The lugs described above have been presented in association with terminals, but according to the invention, they can be used as wire contact elements. In particular, the contact tab can, in the idle state, engage deeply inside the terminal, possibly as far as touching the opposite wall. It is possible to provide an external element, for example the tongue 6la (FIG. 6) raised towards the outside, to open the terminal, in order to allow the introduction of a non-rigid wire.

Figures 11 and 12 describe the application of the invention to a wire clamp contact. In this example, the spiral 81 forms two and a half turns. Two contact tabs 82, 83 are provided, cut to be able to engage deep inside the terminal, each through two windows: 85, 87 for the tab 83 and 86, 88 for the tab 82. On the Figure 12, there is shown in solid lines the terminal deformed by the presence of a wire 91 and the dotted position of the terminal at rest. The end of the tab 83 can come practically into contact with the internal end 90 of the spiral. Wires can thus be pinched in two slightly spaced locations to promote good contact with the terminal. The presence of two turns in the terminal ensures great elasticity.

It goes without saying that the embodiments described are only examples and that it would be possible to modify them, in particular by substitution of technical equivalents, without departing from the scope of the invention.

Claims (10)

1. Electrical connection lug comprising at least one tubular contact part adapted to be removably elastically fixed on a terminal, this part being formed by winding a flat sheet metal sheet substantially rectangular with overlapping of the edges so as to form a spiral winding, characterized in that a tab is cut in the vicinity of one end of the spiral and folded towards the contact face or towards the terminal through a window cut in the adjacent turns, the length of the tab being sufficient to project on the other face of the tube formed by the spiral so as to be able to ensure contact with the terminal, the window being wide enough to allow the tab to move towards one or the other side when the spiral tightens or loosens. 2. Electrical connection terminal according to claim 1, characterized in that the projecting projection of the end of the tab beyond the window is greater than or equal to the thickness of the metal blank constituting the terminal. 3. Electrical connection terminal according to one of claims 1 or 2, characterized in that the tab is formed with an introduction ramp making an angle of 20 to 40 ° with the axis of the terminal. 4. Electrical connection terminal according to one of claims 1 to 3, characterized in that the tab is formed with a latching ramp, making an angle of 40 to 90 ° with the axis of the terminal, preferably 4 ₀ to 6 ₀ °. 5. Electrical connection terminal according to one of the preceding claims, characterized in that the width of the window in the direction perpendicular to the axis of the terminal is at least equal to the sum of the circumferential width of the tab and of three times the distance protruding from the paw. 6. Electrical connection terminal according to one of the preceding claims, characterized in that the spiral comprises at least one and a half turns. 7. electrical connection terminal according to claim 5, characterized in that the height of the window in the direction of the axis of the terminal is less than or equal to one third of the length of the terminal. .8. Electrical connection terminal according to one of the preceding claims, characterized in that the tab is cut at the outer end of the spiral, and is bent inwards. 9. Electrical connection terminal according to one of claims 1 to 7, characterized in that the tab is cut at the inner end of the spiral and is bent outward. 10. Electrical connection terminal according to claim 8, characterized in that it comprises only one turn and that the section is circular over more than half of the periphery.

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