Patent Description:
Zip fasteners are often used in applications where a degree of security is desirable. Locking the zip fastener closed can be achieved, for instance, by latching a slider to a fixture at one end of the zip or, where the zip includes two sliders, by latching the two sliders together.

While a lock, such as a padlock, can be used to lock the zip fastener closed, this may not be convenient or necessary in all circumstances, so it is advantageous to provide a zip with child-proofing, or a degree of security that is sufficient to defeat casual theft. In particular, this may include an arrangement that is difficult to open with a single hand. <CIT> describes such a zip fastener with two sliders each having a like locking pull tab, and in which the pull tabs can be interlocked with one another by a slide-and-turn action that provides the security against casual theft. However, there are drawbacks to this system, related to the appearance of the locking pull tab and its exposed location. Its unconventional shape may undesirably suggest it provides some security function and, particularly for manufacturers making a large range of products, for aesthetic reasons it may not be desired to use the locking pull tabs on all products, so conventional pull tabs cannot be eliminated to reduce the part count in the zip assembly.

<CIT> describes the use of complementary male and female couplers on the two sliders, used to lock the two sliders together. Drawing the sliders together in the axial direction to close the zip also engages the male and female couplers, and they are retained in this closed position by a resilient action. For instance, to remove the male from the female coupler, a resilient tongue is deflected. A drawback of this arrangement is that it provides little or no casual security as moving one slider longitudinally with respect to the other to break the connection (and open the zip) is familiar and intuitive. Attention is also drawn to the disclosure of <CIT> describing a zip fastener in accordance with the preamble of claim <NUM>.

It is an object of the present invention to overcome or substantially ameliorate the above disadvantages or, more generally, to provide an improved zip fastener.

According to one aspect of the present invention there is provided a zip fastener, comprising:.

In a zip fastener of this type some relative movement (between the member and the first slider) in a transverse direction is possible to achieve manually at or near the closed position, due to a combination of the bending flexibility of the stringers and play between the stringers and the slider. In typical applications the zip fastener is used for security in soft bags, such purses, wallets, travel bags, sports bags, backpacks, where the material to which the stingers are fixed is also flexible. However, the required transverse movement is sufficiently small that it can also be used in bags with a hard shell, such as briefcases and suitcases.

Preferably a plane defined by long axes of the stringers separates inner and outer sides of the zip fastener, a first pull-tab attachment post is disposed on the outer side of the first slider, and the transverse slot has a mouth through which the head transversely passes when the male and female coupling parts are connected and disconnected, the mouth being disposed on the outer side of the respective one of the first slider and the member. Positioning the mouth thus makes it readily visible, helping make the requires action to engage the male and female parts simple and intuitive. Preferably the one of the male coupling part and complementary female coupling part is disposed on the outer side of the zip fastener and projects axially from the first pull-tab attachment post.

Preferably the zip fastener further comprises a detent that restricts transverse movement of the male part relative to the female part. Preferably the detent provides an audible indication of engagement between the male and female parts. An audible indication of engagement is beneficial as, owing to the small amount of relative movement between the sliders that connects one to the other, obtaining a visual confirmation of proper connection may be difficult.

Preferably the head projects from opposing sides of the neck and the detent comprises a clip of resilient material with a pair of opposing arms, tips of the arms disposed adjacent the female coupling part such that the transverse slot extends between the tips and the tips engage opposing sides of the male coupling part, with each tip and respective one of the opposing sides comprising one of a projection and complementary recess.

Preferably the head further comprises opposing ramps that, upon connection of the male and female parts, spread apart the ends of the arms to engage the opposing sides of the male coupling part.

Preferably the female part further comprises a stop surface extending into the broad section to abut the head and limit transverse travel of the head in the slot.

Preferably the first slider comprises wedge faces that divide a main channel that receives meshed stringers into two branch channels that receive unmeshed stringers and are disposed on either side of a central plane, wherein the wedge faces taper to diverge in the longitudinal direction from a narrow end adjacent the main channel to a broad end, wherein the female part comprises opposing flanges disposed on either side of the central plane.

Preferably the wedge faces comprise outer faces of the clip.

Preferably the clip is held in a recess in the first slider by a snap fit.

Preferably the first slider comprises wedge faces that divide a main channel that receives meshed stringers into two branch channels that receive unmeshed stringers and are disposed on either side of a central plane, wherein the wedge faces taper to diverge in the longitudinal direction from a narrow end adjacent the main channel to a broad end, wherein the male part comprises a rib that projects from the broad end of the first slider, wherein a proximal end of the rib forms the neck and a distal end of the rib is thickened to form the head.

Preferably the male part comprises a rib that projects from the broad end of the first slider, wherein a proximal end of the flange forms the neck and a distal end of the rib is thickened to form the head; wherein the main channel and branch channels of each slider are bounded by opposing inner and outer walls having edges tapered in the longitudinal direction, a fixture projects from each outer wall and is adapted to receive a pull tab, and on the first slider the rib is connected to the fixture.

Preferably the rib further comprises a circular hole adapted to receive a shackle.

Advantageously, the male and female coupling parts can be made small in the invention, requiring very little material, and requiring a small transverse movement for engagement and disengagement. Even if not mutually engaged to restrain movement to the open position, owing to its size and location the zip fastener is still closes to the extent that even small items could not pass through it, so even on items where casual security or child-proofing is not required it can be incorporated, allowing manufacturers to reduce part counts while still covering a wide range of applications.

Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:.

Referring to <FIG>, a first embodiment of a zip fastener <NUM> generally comprises a first slider <NUM> and a second slider <NUM>, both engaged with a pair of stringers <NUM>, <NUM> (shown schematically) which may be connected together by means of meshed teeth <NUM>, in the well-known manner. Additionally, two pull tabs <NUM>, <NUM> (shown in dashed outline) are provided, and they may be connected to an outer side of the respective slider <NUM>, <NUM>, to allow for improved purchase for the user to pull the sliders <NUM>, <NUM> along the stringers <NUM>, <NUM>. Relative movement between the sliders <NUM>, <NUM> along the stringers <NUM>, <NUM> opens and closes the zip fastener <NUM> or, more specifically, opens and closes an opening <NUM> between the stringers <NUM>, <NUM> and sliders <NUM>, <NUM>.

Front ends of the sliders <NUM>, <NUM> are arranged opposing one another and have a male part <NUM> and female part <NUM> respectively. Rearward ends of the sliders <NUM>, <NUM> each comprise a body <NUM> of like form that is tapered in the longitudinal direction and encloses a main channel <NUM> that bifurcates to form two branch channels <NUM>, <NUM> on either side of a central plane <NUM> that is aligned longitudinally. Mutually inclined pairs of opposing wedge face <NUM>, <NUM> and <NUM>, <NUM> of each slider <NUM>, <NUM> divide the main channel <NUM> that receives the meshed stringers into the two branch channels <NUM>, <NUM> receiving unmeshed stringers <NUM>, <NUM>. On each slider <NUM>, <NUM> the respective wedge faces if each pair <NUM>, <NUM> and <NUM>, <NUM> are inclined in the same direction as the body <NUM> tapers, diverging in the longitudinal direction from a rearward narrow end <NUM> adjacent the main channel <NUM> to a broad end <NUM>. In the first slider <NUM> the wedge faces <NUM>, <NUM> are formed on a web <NUM> which is wedge-shaped and may be integral with the body <NUM> and symmetrical on either side of the central plane <NUM>.

As best seen in <FIG>, the body <NUM> may further comprise opposing inner and outer walls <NUM>, <NUM>, the longitudinal edges of which may be curved to join to integral side walls <NUM>, <NUM>. Edges of the inner and outer walls <NUM>, <NUM> may taper in the longitudinal direction. Each of the side walls <NUM>, <NUM> bounds a part of the main channel <NUM> and a part of one of the two branch channels <NUM>, <NUM>, while the inner and outer walls <NUM>, <NUM> bound both of the branch channels <NUM>, <NUM> and the main channel <NUM> on their respective inner and outer sides. Each of the side walls <NUM>, <NUM> may be divided into two parts by a longitudinal slot <NUM>.

A pull-tab attachment post <NUM>, <NUM>, best seen in <FIG>, may project from the outer wall <NUM> of the sliders <NUM>, <NUM> to receive an opening in one of the pull tabs <NUM>, <NUM>. The pull-tab attachment post <NUM>, <NUM> may be connected to the body <NUM> only at a proximal end <NUM>, <NUM>, and may include a leg part extending outward, and a longitudinally extending part terminating at a free end <NUM>, <NUM>. The pull-tab attachment posts <NUM>, <NUM> are on an outer side of the zip fastener <NUM>, that is on the outer side of a longitudinal-transverse plane <NUM> defined by long axes of the stringers <NUM>, <NUM> that is orthogonal to the central plane <NUM>.

Referring to <FIG> and <FIG>, a male coupling part <NUM> may be generally in the form of a rib projecting longitudinally from the broad end <NUM> and generally bisected by the central plane <NUM>. The male coupling part <NUM> may also project longitudinally from the leg part of the pull-tab attachment post <NUM>. The rib may be integral with the broad end <NUM> and the pull-tab attachment post <NUM>. A distal end of the male coupling part <NUM> may be thickened on both sides to form the head <NUM> of enlarged form, while opposing, generally planar sides <NUM>, <NUM> of the male coupling part <NUM> itself form a neck <NUM> disposed adjacent the head <NUM>. The male coupling part <NUM> is disposed on the outer side of the slider <NUM>. A recess <NUM> in the sides <NUM>, <NUM> may be formed in the rib in the inner side of the zip fastener <NUM>.

On the slider <NUM>, as best seen in <FIG> and <FIG>, the female coupling part <NUM> may comprise opposing flanges <NUM>, <NUM> that project from the broad end <NUM> on either side of the central plane <NUM>. The female coupling part <NUM> may also project longitudinally from the leg part of the pull-tab attachment post <NUM>. The flanges <NUM>, <NUM> may be integral with the broad end <NUM> and the pull-tab attachment post <NUM> and define between them a transverse slot <NUM> with broad and narrow sections <NUM>, <NUM> sized to slidably receive the head <NUM> and neck <NUM> respectively. A shoulder <NUM> is disposed between the narrow section <NUM> and the broad section <NUM> and abuts the head <NUM> to prevent axial separation of the sliders <NUM>, <NUM> when the head <NUM> is in the transverse slot <NUM>. An open mouth <NUM> of the transverse slot <NUM> is disposed on the outer side of the slider <NUM>. Opposite the mouth <NUM> a stop surface <NUM> closes the inner end of the slot <NUM>, and may abut the head <NUM> to limit its transverse travel.

The male coupling part <NUM> and the respective body <NUM> may be integral (forming the slider <NUM>) and, likewise, the female coupling part <NUM> and its respective body <NUM> may be integral, and manufactured as by die casting.

Referring to <FIG>, the zip fastener <NUM> further comprises a clip <NUM> mounted to the slider <NUM>. The clip <NUM> is made of resilient material in a V-shape and comprises a pair of arms <NUM>, <NUM> opposing one another on either side of the central plane <NUM>, integral with one another at one end <NUM> and with respective opposite free ends <NUM>, <NUM>. Upon connection of the male and female parts <NUM>, <NUM>, projections <NUM> on the ends <NUM>, <NUM> first abut the opposing sides <NUM>, <NUM>, before the projections <NUM> enter into the recesses <NUM>, which action causes an audible snap indicative of proper engagement between the male and female parts <NUM>, <NUM>. At the ends <NUM>, <NUM>, outer faces <NUM>, <NUM> of the flanges <NUM>, <NUM> may be coplanar with ends of the wedge faces <NUM>, <NUM> of the clip <NUM> to which they are adjacent. An opening <NUM> in clip <NUM> between the arms <NUM>, <NUM> and between the one end <NUM> and the shoulders <NUM>, <NUM> adjacent the projections <NUM> has a complementary shape to that of the web <NUM> that extends between the inner and outer plates <NUM>, <NUM>. The clip <NUM> is attached by inserting it into the body of the slider <NUM> with one of the arms <NUM>, <NUM> either side of the web <NUM>. The shoulders <NUM>, <NUM> are resiliently urged apart when the clip <NUM> is inserted and snap back to engage face <NUM> of the web <NUM>, forming a snap fit that permanently holds the clip <NUM> in place.

With reference to <FIG>, in use, as the sliders <NUM>, <NUM> are drawn together they are rotated and/or displaced transversely relative to one another in a first transverse direction sufficient to displace the head <NUM> transversely from the mouth <NUM> of the transverse slot <NUM>. This requires two hands, as with one hand grasping each of the pull-tabs <NUM>, <NUM> (not shown in <FIG> for clarity). For instance, slider <NUM> may remain stationary, while slider <NUM> is rotated to the intermediate position shown in <FIG>, where part of the flange <NUM> is shown cut away, along with part of the clip <NUM>. This movement is small, as shown, and requires bending of the stringers <NUM>, <NUM> (not shown in <FIG> for clarity) but is insufficient to cause any significant friction or binding that might tend to restrict free longitudinal sliding of the sliders <NUM>, <NUM>. Subsequently, relative rotation and/ linear displacement in a second transverse direction opposite the first direction initially enters the head <NUM> transversely through the mouth <NUM>. Of course this movement in the second transverse direction is aided by the stringers <NUM>, <NUM> which want to return to their original state. Continued movement in the second transverse direction slides the head <NUM> toward the stop surface <NUM>. As the head <NUM> approaches or contacts the stop surface <NUM> the projections <NUM> snap into the recesses <NUM> with an audible click. The tactile and audible feedback of detent actuation indicates that the sliders <NUM>, <NUM> are properly connected. In this closed position, the head <NUM> is restrained by the shoulders <NUM> from being drawn longitudinally between the lips, while the detent action of the cooperating ends <NUM>, <NUM> and recesses <NUM> restrains the head <NUM> from passing back out of the open end to release the male and female parts <NUM>, <NUM>. Both the detent clip <NUM> and the bending stiffness of the stringers <NUM>, <NUM> tend to maintain the head <NUM> in the slot <NUM>.

On the first slider <NUM> the male coupling part <NUM> further comprises a hole <NUM> adapted to receive a shackle. Like holes <NUM> may be disposed in each of the flanges <NUM>, <NUM> and aligned coaxially. The hole <NUM> is located in registration with the holes <NUM> in the closed position. In this manner, a padlock can be used when a higher degree of security is desired, its shackle (not shown) passing through the holes <NUM>, <NUM> to connect the sliders <NUM>, <NUM>.

With reference to <FIG>, a second embodiment of the zip fastener <NUM> of the invention comprises a slider <NUM> (of like form as in the zip fastener <NUM> and so it is identified with the same reference number) with one of the male and female parts <NUM>, <NUM> and wherein, essentially, the other of the male and female parts <NUM>, <NUM>, previously disposed on second slider, is instead formed on a fixture <NUM> fixed at a longitudinal end of the stringers. The male coupler <NUM> thus likewise opposes the female coupler <NUM>, so zip fastener <NUM> can be held closed in manner corresponding to that of zip fastener <NUM>. The fixture <NUM> may include a flange <NUM> transverse to the male coupling part <NUM>, with holes <NUM> for receiving a fastener for mounting the fixture <NUM>. A hole <NUM> adapted to receive a shackle may also be formed on the fixture <NUM>.

<FIG> illustrates a third embodiment of the zip fastener <NUM> of the invention, which differs from the previously described embodiments in respect of the slider <NUM> on which the female part <NUM> is disposed, the body <NUM> of which may be an assembly of inner and outer sections <NUM>, <NUM> each including a respective one of the inner and outer walls <NUM>, <NUM>. The inner and outer sections <NUM>, <NUM> may each be one-part components and the web <NUM> may be integral with the outer section <NUM>. Dividing the slider in this manner either side of the longitudinal-transverse plane <NUM>, or parallel thereto, allows for servicing of the zip fastener while it is assembled on a bag. A screw <NUM> received in a transverse opening in the web <NUM> may connect the inner and outer sections <NUM>, <NUM>.

Claim 1:
A zip fastener (<NUM>, <NUM>, <NUM>), comprising:
a pair of stringers (<NUM>, <NUM>) defining a longitudinal axis;
a first slider (<NUM>, <NUM>) disposed to slide lengthwise along the stringers and thereby join the stringers and close an opening (<NUM>) between the stringers, the first slider (<NUM>, <NUM>) including, at one axial end thereof, one of a male coupling part (<NUM>) and a complementary female coupling part (<NUM>);
a member (<NUM>, <NUM>, <NUM>) secured to at least one of the stringers (<NUM>, <NUM>), the member (<NUM>, <NUM>, <NUM>) including, at one axial end thereof, the other of the male coupling part (<NUM>) and complementary female coupling part (<NUM>);
the male coupling part (<NUM>) comprising a neck (<NUM>) adjacent an enlarged head (<NUM>), and the female coupling part (<NUM>) comprising a transverse slot (<NUM>) with broad and narrow sections (<NUM>, <NUM>) sized to slidably receive the head and neck (<NUM>, <NUM>), and a shoulder (<NUM>) between the broad and narrow sections (<NUM>, <NUM>) of the female coupling part (<NUM>) abuts the head (<NUM>) to prevent axial separation of the first slider (<NUM>, <NUM>) and the member (<NUM>, <NUM>, <NUM>) when the head (<NUM>) is in the slot (<NUM>), and
the member (<NUM>, <NUM>, <NUM>) is either a) a second slider (<NUM>, <NUM>) that is disposed to slide lengthwise along the stringers (<NUM>, <NUM>) and thereby join the stringers (<NUM>, <NUM>) and close the opening between the stringers (<NUM>, <NUM>), or b) a fixture (<NUM>) on at least one of the stringers (<NUM>, <NUM>); characterized in that the transverse slot (<NUM>) is sized such that relative rotation between the first slider (<NUM>, <NUM>) and the member (<NUM>, <NUM>, <NUM>), and resulting bending of the stringers (<NUM>, <NUM>), allows the head (<NUM>) to be inserted transversely into the slot (<NUM>), and the bending stiffness of the stringers (<NUM>, <NUM>) tends to maintain the head (<NUM>) in the slot (<NUM>).