SNAP FASTENER WITH A DIFFERENTIATED BUTTONING AND UNBUTTONING EFFORT FEMALE PART

Abstract

A snap fastener, of the type comprising a female part (2) including a spring (11, 11a, 11b) and a male part (4) including a stem (5) for engagement with the spring, wherein a chamber (10, 10a, 10b) is provided for housing the spring and including shoulders (12, 12a, 12b) on a buttoning side, the shoulders having a length (L1) longer than a length (L2) of shoulders (13, 13a, 13b) arranged on the opposite side. Thus, a differentiated effort buttoning and unbuttoning mechanism between the stem (5) and the spring (11) is achieved. With respect to prior snap fasteners, the inventive snap fastener provides the advantage of requiring very small buttoning efforts, much smaller than those necessary for unbuttoning the snap fastener, thereby facilitating the snap fastener closing operation while providing a tightness closure upon having buttoned the snap fastener male and female parts.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a snap fastener with a differentiated buttoning and unbuttoning effort female part.

The field of the invention is that of the automatic snap fasteners, in which the stem of the snap fastener male part is engaged in the snap fastener female part and is held therein by a holding spring.

In such a device, it is necessary to provide a given resistance of snap fastener against its “opening” or unbuttoning, without however hindering the buttoning up operation which, on the contrary, should be as fast and easy as possible.

Commercially available snap fasteners do not provide any difference between the buttoning up and unbuttoning effort, thereby the effort required to open or unbutton the snap fastener is normally about the same as that necessary for closing or buttoning it.

The above prior snap fasteners, however, have the drawback that, since the snap fastener should provide a firm tightness after its closure, the buttoning effort is a comparatively high one, thereby rendering the snap fastener closing or buttoning operation a rather difficult one, mainly at positions without a biasing abutment or with a yielding abutment.

Document US 2014/109352 A1 discloses a snap fastener, wherein the opposite shoulders of a chamber including the snap fastener female part spring have a substantially like length, thereby the engaging of snap fastener stem in the female part causes an exclusively radially extending deformation of the spring.

Document EP 2 441 340 A1 discloses a snap fastener including a spring housed in a chamber, which chamber has, in turn, a shoulder on a buttoning side which is shorter than a corresponding shoulder on the opposite side. Since this prior snap fastener requires a comparatively high closing or buttoning effort, said spring is formed with built-in resilient deformable tongues so designed as to facilitate the snap fastener closing operation, while having however the disadvantage of reducing the snap fastener tightness or effort against an accidental and undesired opening thereof.

SUMMARY OF THE INVENTION

Accordingly, the main object of the present invention is to provide a novel snap fastener which, differently from prior like fasteners, facilitates the buttoning operations without negatively affecting its tightness in its closing or buttoned up condition.

Another object of the invention is to provide such a snap fastener of a simple construction and small thickness, which may be easily made with low making costs.

The above mentioned and yet other objects are achieved by the inventive snap fastener according to claim 1.

Preferred embodiments of the invention are claimed in the subclaims.

With respect to prior snap fasteners, the inventive snap fastener provides the advantage that it requires a very small buttoning up effort, much smaller than that necessary for unbuttoning it.

Thus, the snap fastener closing or buttoning up operations are simplified and facilitated, while providing a tight closure after having buttoned up the snap fastener male and female parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and yet other objects, advantages and features of the invention will become more apparent from the following disclosure of preferred embodiments of the invention which is illustrated, by way of non-limitative examples, in the figures of the accompanying drawings, where:

FIG. 1 is an exploded cross-sectional view of a first embodiment of the snap fastener according to the present invention;

FIG. 2 is a perspective view showing a ring or annular spring of the female part of the snap fastener shown in FIG. 1;

FIG. 3 shows a detail of a cap-shaped body of the female part of the snap fastener shown in FIG. 1;

FIGS. 4 and 5 show the snap fastener of FIG. 1, during its buttoning up and unbuttoning operations, respectively;

FIG. 6 is an exploded cross-sectional view showing the female part of a snap fastener including two female components;

FIG. 7 shows the snap fastener including the female part shown in FIG. 6;

FIG. 8 shows a modified embodiment of the snap fastener of FIG. 1; and

FIGS. 9 and 10 show a further modified embodiment of the snap fastener according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The snap fastener according to the invention, which has been generally indicated by the reference number 1 in FIG. 1, comprises a snap fastener female part 2 clamped on a first support flap 7 (either of a fabric or other material) by a clamping head 3.

A snap fastener 1 male part 4 cooperates with the above female part 2, said male part including in turn a male part stem 5 and being clamped on a second support 8 by a clamping element 6.

More specifically, said female part 2 comprises a cap-shaped body 9, defining therewithin a holding chamber 10 for holding a spring 11, preferably made of a plastics material ring element (see FIG. 2).

As clearly shown in FIGS. 3 and 4, the chamber 10 of the cap-shaped body 9 comprises a shoulder 12, on the male part engaging side, said shoulder having a length L1, as well as a further shoulder 13, on the opposite side, having a length L2, said length L1 being longer than said length L2.

The above different lengths of the shoulders 12 and of the cap-shaped body 9 provide the spring 11, housed in the chamber 10, with corresponding spring free portions, i.e. a longer portion 14 on the shoulder 13 side and a shorter portion 15 on the shoulder 12 side, respectively.

Thus, in the above embodiment and as is shown in FIGS. 4 and 5, a deformation of the spring 11 as the stem 5 is engaged in the female part 2 (see the arrow F1 in FIG. 4) is facilitated by the longer length of the free portion 14 of said spring 11.

On the contrary, the shorter length of the free portion 15 of said spring 11, on the stem 5 engaging side, will provide an enhanced or higher resistance against an unbuttoning (see the arrow F2 in FIG. 5), thereby differentiating from the smaller effort required for the buttoning up operation.

Advantageously, and as is clearly shown in FIGS. 9 and 10, the length L3 of the annular spring 11 is substantially equal to the length L1 of the shoulder 12 of the chamber 10 of the cap-shaped body 9 of the inventive snap fastener female part 2, and projects from said shoulder 12 only at an edge 19 of an inner hole 20 of said annular spring 11. Thus, the portion L1 of the shoulder 12 covering the spring 11 will stiffen said spring, allowing it to efficiently hinder any unbuttoning effort. On the other hand, in the buttoning up operation, the stem 5 of the snap fastener male part will contact the free edge 19 of the spring 11, thereby facilitating a mutual centering and coupling thereof.

In the modified embodiment shown in FIGS. 6 and 7, the female part 2 comprises two female bodies 2a, 2b which may be coupled to one another by pointed portions or tips 16 of the body 2a which are clamped within corresponding seats 17 of the body 2b.

Each said female body 2a, 2b forms in turn an inner chamber 10a, 10b for housing a corresponding spring 11a, 11b.

Said chambers 10a, 10b are also provided with different length shoulders, i.e. longer shoulders 12a, 12b on the buttoning side and shorter shoulders 13a, 13b on the opposite side, respectively.

The above configuration will in turn provide on the respective springs 11a, 11b longer spring free portions 14a, 14b and shorter spring free portions 15a, 15b, with the operating effects as previously disclosed with reference to the embodiments of FIGS. 4 and 5.

The invention, as above disclosed, is susceptible to several modifications and variations all coming within the scope of the following claims.

Thus, in particular, as shown in FIG. 8, the loop or ring element 11 has a slanted wall beveled portion 18 to facilitate the engagement of the snap fastener male part.

Moreover, the ring or loop element 11 may also be made in different configurations, depending on corresponding configurations of the chamber 10 of the snap fastener female part body 9, as is shown, for example, in the accompanying FIGS. 9 and 10.

Claims

1. A snap fastener, of a type comprising a female part (2) including a ring spring (11, 11a, 11b) having an inner hole (20) and a male part (4) having a male part stem (5) for engaging with said ring spring, characterized in that said snap fastener further comprises engagement means with differentiated buttoning and unbuttoning efforts, between said stem (5) and said ring spring (11).

2. A snap fastener, according to claim 1, characterized in that said engagement means comprise a chamber (10, 10a, 10b) for housing said ring spring (11, 11a, 11b) and having shoulders (12, 12a, 12b) on a buttoning side, said shoulders having a length (L1) longer than a length (L2) of corresponding shoulders (13, 13a, 13b) arranged on an opposite side.

3. A snap fastener, according to claim 2, characterized in that said longer shoulders (12, 12a, 12b) leave on said ring spring (11, 11a, 11b) corresponding shorter free portions (15, 15a, 15b), and that said shorter shoulders (13, 13a, 13b) leave on said ring spring (11, 11a, 11b), corresponding longer free portions (14, 14a, 14b).

4. A snap fastener, according to claim 3, characterized in that said ring spring (11) comprises a slanted wall beveled portion (18) facilitating the engagement of the snap fastener male part (4).

5. A snap fastener, according to claim 3, characterized in that said female part (2) comprises two female bodies (2a, 2b), each said female body defining in turn an inner chamber (10a, 10b) for housing a corresponding spring (11a, 11b).

6. A snap fastener, according to claim 5, characterized in that said chambers (10a, 10b) comprise chamber shoulders having different lengths, namely longer chamber shoulders (12a, 12b) on the buttoning side and shorter chamber shoulders (13a, 13b) on an opposite side, respectively.

7. A snap fastener, according to claim 6, characterized in that said springs (11a, 11b) comprise spring longer portions (14a, 14b) and spring shorter portions (15a, 15b), thereby an engagement of said stem (5) in said female bodies (2a, 2b) is facilitated by the longer length of said spring free portions (14a, 14b), the shorter free portions (15a, 15b) of said springs (11a, 11b) on the stem (5) engagement side providing an enhanced resistance against unbuttoning.

8. A snap fastener, according to claim 3, characterized in that a length (L3) of said ring spring (11) is substantially equal to said length (L1) of said shoulder (12) of the chamber (10) of the body (9) of the snap fastener female part (2) and projects from said shoulder (12) only at an edge (19) of the inner hole (20) of said ring spring (11).