Slider for zip fastener with two tabs and a single fork for releasing the slider

A slider (1) for zip fasteners with two tabs (2, 3), comprising a hollow body (4) in which are positioned structure (10, 5, 6) designed in such a way that, when either one of the two tabs (2, 3) is pulled, this causes the disengagement of a pawl (7) from the teeth (Zi) of a fastener, overcoming the resistance of elastic structure (8, 9) which keep the pawl inserted between the teeth (Zi). In the slider (1) a fork (10) is provided with two prongs (5, 6) positioned on opposite sides of the plane (β) of the teeth (Zi) and pivoted at a point (P, Q) of the slider (1) in such a way that it can rotate in a plane (α) perpendicular to the plane (β) of the teeth (Zi) when a force is exerted on at least one (6) of its prongs (5, 6) by the tab (3) connected to it by its ring (3a).

An example of such a slider is described in the patent EP 204 186 B1 held by YKK, and another example is illustrated in Swiss patent application 01697/03 filed by the present applicant.

The present invention relates to the field of what are called “zip fasteners”, in other words fasteners which can be opened and closed by pulling on either one of two tabs connected on opposite sides, by means of their rings, to a slider, in other words to the member which joins and disengages the teeth of the fastener.

In both of the said examples, the slider is locked in its position by means of a pointed member which penetrates between the teeth of the fastener, and in order to move the slider it is first necessary to disengage this member, which can also be called a “pawl”, from the teeth.

To ensure that this locking operation can be performed by pulling as stated on either one of the two tabs connected to the slider, the terminal rings of the tabs are connected to two levers, located inside the hollow body of the slider on opposite sides of the plane of the fastener, and interconnected by contact or by means of suitable return members. One of these levers is connected integrally to the aforesaid pawl, and the levers are designed and positioned in such a way that a pull on either one of the two tabs will directly or indirectly cause the movement of the pawl in such a way as to disengage it from the teeth of the fastener.

The manufacture of the levers described above and of the corresponding actuating systems entails production and assembly costs which, given the intrinsically relatively low value of a slider with two tabs, have a significant effect on the final cost.

Moreover, since an increase in the number of parts of an assembly also increases the potential causes of malfunction, the reliability of sliders made as described above can sometimes be inadequate, and in order to achieve correct operation it is necessary to use more costly methods and materials, which in turn have an additional effect on the price.

The inventor of the slider with two tabs according to the present invention has devised a solution in which the aforementioned two levers form a single piece, and more specifically a single fork whose two prongs perform the function of the two levers. This fork, connected by means of the aforesaid prongs to one of the sliders and to the pawl described previously, is pivoted within the hollow body of the slider, and is shaped and positioned in such a way that, by pulling as stated on either one of the two tabs, the user can act on the pawl in such a way that it is disengaged from the teeth of the fastener so that the slider can be moved.

Like all sliders with two tabs, the slider according to the invention, as described below, comprises elastic means for keeping the pawl inserted between the teeth of a fastener until, when the prongs are acted on, these means are deformed elastically to a sufficient degree to disengage the pawl.

The object of the present invention is therefore a slider for fasteners with two tabs as described in the attached claim1.

With reference initially toFIGS. 1,2,3, these show how, in a slider1with two tabs2and3according to the invention, its hollow body4houses within it a fork10, pivoted at a point P of the slider and consisting of two prongs5and6positioned on opposite sides of the plane β occupied by the teeth Zi of a fastener (not all of which is shown). A flexibly elastic strip8terminates in a pawl7, and the strip8is shaped in such a way that, when no force is applied to it, its pawl7is kept inserted between the teeth Zi to keep the slider1locked. The strip8is positioned so that it faces and is parallel to one prong5of the fork10.

The tab2in the upper part of the drawing is connected by its ring2ato the strip8in such a way that pulling the tab (seeFIG. 2) causes the pawl7to be disengaged from the teeth Zi (arrow M).

The tab3in the lower part of the drawing is connected by its ring3ato the prong6in the lower part of the drawing, and pulling this tab causes a rotation (arrow R inFIG. 3) of the fork10about the point P, in a plane α perpendicular to the plane β of the teeth Zi, which makes the prong5in the upper part of the drawing, which is in contact with the strip8, cause an elastic deformation of the strip in this case also, thus disengaging the pawl7from the teeth Zi (arrow N).

It should be noted that, whereas the tab2in the upper part of the drawing acts directly by traction on the strip8, the tab3in the lower part of the drawing acts on the prong6by pressing with its ring3aon a surface with inclined planes S in such a way as to cause the rotation R of the fork10.

This system of connection by means of inclined planes is known to those skilled in the art.

FIG. 4shows another example of embodiment11of the slider according to the invention. In this case also, the slider11has a hollow body14in which is housed a fork20with two prongs15and16, pivoted at a point Q in such a way that it can rotate (arrow O,FIGS. 5 and 6) in a plane α perpendicular to the plane β of the teeth Zi of the fastener (again not all of which is shown).

In this case, however, the pawl7does not form part of a separate member, but is formed integrally on the free end15tof a prong15, which is drawn in the upper part of the figure.

As shown inFIGS. 5 and 6, pulling on either one of the two tabs2and3connected by their rings2aand3ato the two prongs15and16makes the fork20rotate in the direction of the arrow O, thus extracting (arrow V) the aforesaid pawl17from the teeth Zi of the fastener.

In this case, the elastic force which keeps the pawl17inserted between the teeth Zi is provided by a spring9interposed between the fork20and the hollow body4of the slider11, the spring being positioned and designed in such a way as to oppose the rotation O of the fork20.

In both embodiments described above, a slider1,11according to the invention is provided, this slider consisting of a smaller number of components and being consequently more reliable and less expensive to produce.