Snap-on, plastic hinged closure in a single piece

A snap-on, plastic hinged closure in a single piece having a bottom part and a lid interconnected by an integral hinge in an area of superimposed outer walls of the bottom part and lid, as well as by at least one intermediate element that ensures the snap-on effect. The hinge includes at least two non-intersecting pivot axes. A pressure-resistant tilting element is arranged between two adjacent pivot axes, so that during opening or closing, the first bottom part and the tilting element, then the tilting element and the lid partially pivot around the corresponding pivot axis.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a one-piece snap-on plastic hinged closure, 
having a lower part and a lid, which are connected with each other with an 
integral joint in the area where the jacket walls of the lower part and 
the lid are superimposed on each other, as well as with at least one 
intermediate element which creates the snap effect. 
2. Description of Prior Art 
Snap-on plastic hinged closures of the type mentioned above are known in 
large numbers and multitudinous designs. Conventional plastic closures 
mainly include two basic elements. For one, they have a main joint around 
which the pivot movement of the lid in relation to the lower part takes 
place, and they furthermore have one or several intermediate elements 
creating the snap effect. Such intermediate elements can be in the form of 
straps, triangles or angled flexible springs or even longitudinally 
deformable tension spring elements. 
The essential part of this invention is focused upon the design of the 
joint connecting the two parts, the lower part and the lid. This joint is 
typically embodied as a film hinge in one-piece, snap-on plastic hinged 
closures. In the completely closed or the completely opened state of the 
closure this film hinge is not subjected to a force. In all intermediate 
positions, compression and displacement forces are exerted on this film 
hinge. The formation of microscopic cracks and scores can be noted upon a 
close inspection. Stretching of the film hinge, as well as greatly 
spreading white fracture places can be clearly seen in the area of the 
film hinge. These conventional uniaxial hinges are stressed most in the 
range of the unstable equilibrium during each opening or closing 
operation. The forces generated by the intermediate elements do pull the 
two closure parts toward each other, but since they are not located 
vertically above each other in all intermediate positions which differ 
from the completely closed position, a reaction force is created which 
must be absorbed by the film hinge. If the tension forces are reduced in 
general, the life of the film hinge is extended, however, the snap effect 
of the closure is simultaneously and to a large extent lost. 
The second problem with the design of the joint between the lower part and 
the lid is that the joint always projects out in relation to the jacket 
wall. That fact that this joint projects out in relation to the jacket 
walls is on the one hand the result of the geometry of the snap-on hinged 
closures and, on the other hand, it is done for reasons of manufacturing 
technology. The more the joint projects out in relation to the jacket 
wall, the greater is the snap effect of the closure and conversely this 
snap effect is reduced the less the joint projects out in relation to the 
jacket walls. Since customarily the snap hinges are injection-molded in 
the completely open position, a vertical wall of material remains in the 
injection mold below the joint. If the joint is designed to sit as closely 
as possible to the jacket walls, this wall of material in the injection 
mold becomes so thin that the service life of the injection mold is 
reduced and it becomes very prone to defects. 
SUMMARY OF THE INVENTION 
Therefore this invention has as one object to provide a one-piece, snap-on 
plastic hinged closure with a joint that is designed in such a way that 
the previously described disadvantages associated with conventional 
one-piece, snap-on plastic hinged closures are remedied to a large extent. 
The above and other objects of this invention are achieved with a 
one-piece, snap-on plastic hinged closure having a lower part and a lid 
which are connected with each other with an integral joint in an area 
where jacket walls of the lower part and the lid are superimposed on each 
other. At least one intermediate element connected between the lower part 
and the lid creates a snap effect. The joint includes at least two 
adjoining pivot axes and a compression-resistant flip element positioned 
between the two adjoining pivot axes, so that during the closing or 
opening operation respectively, one sequential partially pivoting about 
one pivot axis occurs between the lower part and the flip element and a 
further partial pivoting around another pivot axis occurs between the flip 
element and the lid. Further advantageous embodiments ensue from the 
dependent claims which are discussed and further explained in the 
description which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS 
No further reference will be made here to the two FIGS. 1 and 2 of the 
drawings, which represent a joint of a conventional snap-on hinged 
closure. 
A snap-on hinged closure in a closed and mounted state is shown in FIG. 3. 
The lower part 1 of the closure is positioned on a neck, which is not 
shown in the drawings, of a container 4. The essentially cylindrical lower 
part 1 can be closed by a lid 2, as shown in FIG. 3. The lower part 1 and 
the lid 2 are connected with each other by the two triangular intermediate 
pieces 3 and are integrally formed together at two pivot axes 6a, 6b with 
the compression-resistant flip element 7 interposed between them. The two 
intermediate elements 3 are used to create a snap effect. In the closed 
state the entire snap hinge can hardly be seen from the outside. The two 
pivot axes 6a, 6b have been drawn as dash-dotted or phantom lines as 
extending straight and parallel to each other only for reasons of 
clarification. The jacket walls of the lower part 1 and of the lid 2 are 
flat in the area of the pivot axes 6a, 6b because of a flattening portion 
13. A push element 5 is disposed on the lid 2 on the side of the closure 
opposite the hinge in order to make access for opening the closure easier, 
which is clearly seen in FIG. 4. 
FIG. 5 shows a vertical section taken through the snap-on plastic hinged 
closure along the line X--X as shown in FIG. 3. The pouring spout 8, 
surrounded by a concentric outer wall 14, which can be clamped on a 
container neck, can also be seen in FIG. 5. An annular wall 9 which 
sealingly extends around the spout 8 is disposed on the inner surface of 
the lid 2. The compression-resistant flip element 7 can be seen, and it 
can also be clearly seen that the pivot axes 6a, 6b extend symmetrically 
in relation to a plane of separation T, indicated by a dashed line. It can 
further be seen that the pivot axes 6a, 6b are disposed within the jacket 
walls and thus form a non-protruding hinge, for the first time in this 
type of snap closures. The jacket wall of the lower part 1 is indicated by 
element reference numeral 10, the jacket wall of the lid 2 by element 
reference numeral 11. 
The particularly important joint of this invention is shown in FIG. 6 in an 
enlarged scale. The situation of the completely opened closure is 
illustrated in FIG. 6. It can be clearly seen that in a sectional view the 
flip element 7 has the general shape of an isosceles triangle. In the 
preferred embodiment shown in FIG. 6, the triangle is a right-angled 
isosceles triangle. Accordingly, the flip element 7 is bounded on both 
sides by the thin areas 12a, 12b , which define the pivot axes 6a, 6b, 
respectively. This roof-shaped compression-resistant flip element 7 thus 
forms a support surface 15a on one side and a support surface 15b on 
another side of the compression-resistant flip element 7. In the closed 
state of the closure, the one support surface 15a comes to rest on an 
inclined opposite surface 16 on the lower part 11, and the other support 
surface 15b comes to rest on an inclined opposite surface 17 on the lid 2. 
The opening angle between the support surface 15a and the opposite surface 
16 on the lower part 11, as well as between the oppositely located support 
surface 15b and the opposite surface 17 on the lid 2 is respectively 
90.degree.. This permits the division of the pivot movement of the lid 2 
with respect to the lower part 1 into respectively two pivot movements of 
respectively 90.degree.. 
Basically, it is possible for the angle between the two support surfaces 
15a and 15b to be less than 90.degree., however, this requires that the 
opposite surfaces 16 and 17 be designed somewhat flatter. The smaller the 
angle between the two support surfaces 15a and 15b, the more the flip 
element 7 would project into the closure. But since the portion of the 
support surfaces 15a and 15b projecting past the opposite surface 16 or 17 
is ineffective, the triangular portion of the flip element 7 can be 
truncated, as illustrated in FIG. 7. This results in a flip element 7 
which in cross section has the general shape of an isosceles trapezoid. 
Approximate right angles .alpha.,.beta. which are to be maintained between 
the support surfaces 15a and 15b and the opposite surfaces 16 or 17 are 
also indicated in FIG. 7. 
It is possible to apply two different angles, which would complement each 
other to form 180.degree., in place of the two right angles. But such 
embodiment results in an inclination of the flip element 7 in the 
completely closed position of the closure. This may be desirable in 
exceptional cases for specially designed closures. 
It can also be seen in FIGS. 6 and 7 that the thin areas 12a and 12b 
forming the pivot axes 6a, 6b are situated inside of the jacket walls 10 
or 11 of the lower part 1 or the lid 2. 
When closing the closure of this invention, the lid 2 together with the 
flip element 7 is first pivoted around a pivot axis 6a between the support 
surface 15a and the opposite surface 16 on the lower part 1 until these 
two surfaces come to rest on each other, after which during pivoting over 
a further 90.degree. the pivot movement around the second pivot axis 6b 
between the support surface 15b and the opposite surface 17 on the lid 2 
takes place. These two pivot movements take place in a reversed manner 
during opening. 
If now the spring characteristics of conventional snap-on hinged closures 
and of the snap-on hinged closures of this invention are compared, the 
corresponding characteristic lines in FIGS. 8 and 9 result. FIG. 8 shows a 
conventional snap-on hinged closure with a joint having only one pivot 
axis 6, and it can be seen that in the area of dead center a maximal shape 
change of .DELTA.1 occurs, while the snap-on hinged closure in accordance 
with this invention with two pivot axes 6a, 6b considerably reduces the 
maximal shape change. This results in a longer, relatively large pivot 
force over the entire pivot movement of the lid without, however, causing 
a deformation of such a size as with the uniaxial design of the joint. By 
means of this the complete opening of the lid over 180.degree. is also 
assured. Up to now this has been only a desirable idea which, however, was 
never accomplished. Furthermore, by means of these graphics it is possible 
to explain that a considerably reduced maximum load is placed on the joint 
or the two pivot axes 6a, 6b, which results in a reduction of the 
formation of cracks and scores. Stretching or white fractures, which can 
be clearly seen by the naked eye when they occur in snap-on hinged 
closures in accordance with the state of the art, can hardly be detected 
in the closures of this invention.