US 20010006164 A1
A flask having a retractable body of approximately cylindrical plastic material formed by a succession of conical upper and lower sections connected at their apexes and in their troughs, an angle α being formed between the conical upper section and a transverse plane and an angle β being formed between the conical lower section and a transverse plane, wherein the succession of conical sections alternate rigid/flexible, making it possible to obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and wherein the radius of curvature of the troughs is less than or equal to about 0.2 millimeters.
1. A flask having a retractable body of approximately cylindrical plastic material formed by a succession of conical upper and lower sections connected at respective apexes and troughs, an angle α being formed between the conical upper section and a transverse plane and an angle β being formed between the conical lower section and a transverse plane, wherein the succession of conical sections alternate rigid/flexible, to thereby obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and wherein the radius of curvature of the troughs is less than or equal to about 0.2 millimeters.
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 This is a continuation of International Application No. PCT/FR99/01496, with an international filing date of Jun. 22, 1999, which is based on French Patent Application No. 98/08193, filed Jun. 22, 1998, French Patent Application No. 98/08420, filed Jul. 1, 1998, and French Patent Application No. 98/15945, filed Dec. 17, 1998.
 This invention concerns flasks, in particular feeding bottles. More particularly, this invention relates to retractable feeding bottles, the height of which may be reduced outside periods of use.
 In the state of the art, different versions of flasks or retractable bottles have been proposed.
 FR 2467146 discloses in particular semi-rigid packaging constituted by a ringed sleeve the corrugations of which, with an essentially triangular shaped cross-section, allow stable contraction by tilting a part at least of them beyond a position of equilibrium so that each of the corrugations has a stable position in the compressed state or in the deployed state. The sleeve delimits an inner volume which can vary in a substantial ratio between extreme states where all the corrugations are compressed or deployed.
 U.S. Pat. No. 5,348,173 discloses embodiment details of such retractable packaging.
 Also known are U.S. Pat. No. 2,780,378, U.S. Pat. No. 3,143,429, GB 2181062 and EP 300786 concerning compressible containers also having the general shape of bellows. Indeed, prior art products retain compression memory: when the feeding bottle is decompressed after a long period of being kept in the compressed position, it does not regain its nominal capacity.
 These types of packaging have defects, however. They do not guarantee the capacity in the deployed position. Indeed, significant variations may occur when the prior art packaging is subject to multiple extension and retraction manipulations.
 On the other hand, prior art devices do not guarantee harmonious and regular compression or deployment of the bellows, and often do not guarantee the stability of the extreme and intermediate positions.
 These drawbacks make the prior art device unsuitable for some applications, particularly for the manufacture of a feeding bottle.
 Indeed, for such applications, certain characteristics are required. It is desirable for the capacity of the feeding bottle in the deployed position to be constant and reproducible, to allow a precise dosage of the content by means of lateral calibration marks.
 Prior art devices do not allow such consistency of capacity to be guaranteed, and the lateral marks which could be affixed to the wall would not allow the volume of liquid introduced into the packaging to be deduced. Moreover, it will be noted that the prior art does not suggest using such calibration marks.
 Secondly, a feeding bottle must be sufficiently stable, in the deployed position, to prevent unexpected axial pressure from causing an untimely compression. Such a compression would have very prejudicial effects, creating excess pressure of the contents, a liquid overflow, and a risk of choking the baby by excess of liquid delivered by the feeding bottle.
 Finally, it may be desirable for the capacity of the feeding bottle to be able to be periodically adjusted to expel the air, to reduce the risks of absorption of air by the baby. The absorption of excessive air causes risks of aerophagia finding expression, for the baby, in abdominal pains. For this reason it must allow compression into stable intermediate positions.
 Furthermore, the bellows shape in the retracted or partially compressed position must allow a liquid flow without the formation of areas of stagnation of the liquid contained in the container.
 Thus, it would be highly advantageous to improve prior art bellows packaging to overcome these drawbacks.
 The invention relates to a flask having a retractable body of approximately cylindrical plastic material formed by a succession of conical upper and lower sections connected at their apexes and in their troughs, an angle α being formed between the conical upper section and a transverse plane and an angle β being formed between the conical lower section and a transverse plane, wherein the succession of conical sections alternate rigid/flexible, making it possible to obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and wherein the radius of curvature of the troughs is less than or equal to about 0.2 millimeters.
 The invention will be better understood from reading the following description of an embodiment example, with reference to the appended drawings wherein:
FIGS. 1 and 2 show cross-section views of an embodiment detail of a feeding bottle, in the decompressed and compressed positions, respectively.
FIGS. 3 and 4 show cross-section view of the feeding bottle.
FIGS. 5 and 6 show views of details of the feeding bottle body.
 The following description is intended to refer to specific embodiments of the invention illustrated in the drawings and is not intended to define or limit the invention, other than in the appended claims. Also, the drawings are not to scale and various dimensions and proportions are contemplated.
 The invention concerns a flask, in particular a feeding bottle, having a retractable body of approximately cylindrical plastic material, characterized in that the body is constituted by a succession of conical, alternate rigid/flexible sections making it possible to obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and in that the angle α is greater than the angle β, wherein
 α denotes the angle formed between the upper edge and a transverse plane and
 β denotes the angle formed between the lower edge and a transverse plane.
 Preferably, α-β is greater than or equal to about 4°. To this end, the upper edge is thicker and, therefore, more rigid than the lower edge, which is thereby more flexible than the upper edge.
 Advantageously, the radius of curvature of the connection zone between the conical upper wall and the conical lower wall is greater than or equal to twice the thickness of the wall. The angle β formed between the transverse plane and the conical lower wall is between about 35° and about 40°.
 According to one particular variant, the ratio I/R between the length I of the lower edge and the radius R at the trough is between about 0.35 and about 0.50.
 According to another variant, the bottom has a ring to exert traction on the body of the feeding bottle. Advantageously, the ratio between the generators S and I of two consecutive conical sectors is about 1.25.
 According to an advantageous embodiment, the flash according to the invention has on its wall calibration marks for determining the volume of liquid contained in the bottle in the deployed position.
 The feeding bottle body according to the invention, shown in the appended figures, is constituted by a succession of conical sections (1 to 2) connected, when the feeding bottle is in the deployed position, in the shape of lenses to form a corrugated hollow body. These conical upper (1) and lower (2) sections are connected at their apexes (100) and in their troughs (200).
 When the feeding bottle is compressed as shown in FIG. 2, the conical lower section (1) is folded back under the conical upper section (2). The conical lower section (2) tilts relative to the transverse median plane (300). The lower section (2) is above the transverse plane (300) passing through the trough (200) of a lenticular segment (400) when the feeding bottle is deployed. It is beneath the transverse plane (300) when the feeding bottle is compressed.
 The feeding bottle will be described below as a non-restrictive example, for a maximum capacity (corresponding to the deployed position) of the container of 305 milliliters, for a height of 147.4 mm and a maximum cross-section of 64 mm.
 The body includes a plurality of lenticular elements (3 to 10) formed by the affixing of two conical sections (1,2) as shown in FIG. 3.
 The connection between two lenticular elements, at trough level, has a radius of curvature close to 0, in any case lower than or equal to about 0.2 millimeters. The thickness is an element which may upset component operation, compression and decompression and the maintenance of the spiral track in the compressed position, it can even prevent compression if it is substantial.
 1—Influence of the optimum distribution of thicknesses on the geometry.
 2—Influence of the rigidity of the material: Young's modulus on compression and decompression stresses.
 The compression and jointing condition of a spiral track at thickness level without mentioning compression energy but only feasibility is expressed by a trough radius in the vicinity of 0 to 0.2 millimeters. The trough is an intersection of the thickness of the lower edge and upper edge.
 At this point contrary to the apex, the material expands less on account of its proximity to the center.
 To create the jointing, it is necessary to break the accumulation of materials at this point so that the spiral track compresses and stays compressed.
 The mechanisms engaged during compression of the feeding bottle are as follows:
 Two buckling mode types may appear:
 1. The first mode is a mode accompanied by large displacements which leads to a sharp increase in the rigidity of the component (FIG. 5).
 2. The second is a more local mode accompanied by much smaller displacements localized on the edges of the spiral tracks. The appearance of this second mode does not induce any appreciable increase in rigidity (FIG. 6).
 A non homogenous distribution of the thicknesses (thicknesses at the apexes, troughs and edges of different spiral tracks according to the spiral tracks) favors the appearance of the first buckling mode. The direct consequence of homogenizing the thicknesses is a reduction in the energy required for compression.
 Reducing the thickness in the troughs of spiral tracks and at the apexes allows a substantial gain in compression energies. But in both cases, the reductions in thickness do not make it possible to have better control of the buckling mode appearance and type shown in FIGS. 5 and 6.
 Introducing a more substantial thickness on the upper edges than on the lower edges of the spiral tracks makes it possible on the one hand to control more effectively and to anticipate the appearance of first mode types by increasing the rigidity of the upper edges, on the other hand to create preferential flexion areas on the lower edges. This design, therefore, allows a consequent gain in the energy necessary for compressing the feeding bottle.
 Decompression does not lead to the buckling mode appearance but the previous conclusions remain true. A more homogenous distribution of thicknesses makes it possible to reduce energy in decompression, the hinge effect at the apexes is more pronounced than that in the troughs, the creation of thicker and, therefore, more rigid areas on the upper edges and correlatively that of preferential flexion areas on the lower edges makes it possible to reduce the energy required for decompression.
 Reducing the Young's modulus of the material does not bring consequent gains relative to those stemming from an optimized distribution of thicknesses. Reducing the modulus, if it leads to lower compression energies, leads also to more flexible components the stability, particularly lateral, of which in operation may be much reduced.
 A better distribution of thicknesses and possibly a material of a Young's modulus of less than about 950 Mpa, (800 and 650 Mpa) makes it possible tor educe (almost 100%) the energy necessary for decompressing and compressing the feeding bottle. It must be noted that for an identical effort, the decompression energy is overall equivalent to the compression energy but that the observations made above make it possible to decompress the feeding bottle with low intensity efforts which do not allow compression. The feeding bottle may, therefore, overall be decompressed with less effort than that required to compress it.
 The lower lenticular element (3) includes a lower element the external cross-section of which is 64 mm and the height 5.4 mm, and an conical upper element the generator of which is 13.0 mm, and forms with the vertical an angle of 28.5°. The total height of this first lenticular element (3) is 17.7 mm.
 As shown in FIG. 4, the following lenticular element (4) has a height of 16.9 mm. The conical lower sector has a length of 8.9 mm and forms with the vertical an angle of 39°. The conical upper sector has a length of 10.5 mm, and forms with the vertical an angle of 44°.
 The five following lenticular elements (5 to 9) are formed by a conical lower sector the generator of which has a length of 10.2 mm and forms with the vertical an angle β of 40°, and of an conical upper sector the generator of which has a length of 12 mm and forms with the vertical an angle α of 47°.
 To avoid the effects of hysteresis, it is necessary to respect a certain geometry of the edges between themselves. The dimensions and angles are denoted in references in FIG. 3.
 Dimension of the Lower edge=I
 Dimension of the Upper edge=S
 R—Radius from the trough to the center, on the transverse plane.
 α is the angle formed between the upper edge and the transverse plane.
 β is the angle formed between the lower edge and the transverse plane.
 For the feeding bottle according to the invention, the following formulas are maintained:
 α being the angle of the upper edge, β that of the lower edge which buckles.
 I/R must be between 35% and 50%.
 In the example described,
 I=8.9 mm.
 R=25 mm. The ratio is 35.6%.
 α must be greater than β by at least about 4°. This value includes the possible thickness of the lower edge. Ideally, β must be between about 35° and about 40°. Beyond about 40°, it becomes difficult to compress it.
 α must be greater by at least about 4° relative to β since after kinematics, the lower edge β will be positioned at β′. If β′ stops against the upper edge at β′-α, the lower edge does not compress but is deformed and may rebound. If the dimensions are respected furthermore, alpha must be larger but must not exceed about 20%.
 According to an embodiment example,
 β=39% (β=88% of α)
 The closer the angle β to the straight line which starts from the apexes, the easier the compression. The concept of retractable flasks the height of which may be reduced outside periods of use is applied here for disposable feeding bottles characterized by a spiral geometry.
 The feeding bottle is sold sterile and compressed. It must, therefore, be decompressed to be used. After use, the feeding bottle is compressed to be disposed of. In every case, the user must be able to decompress and compress the feeding bottle easily. On the other hand, he/she must be able to use it without there being a risk of compression during use. For such feeding bottles, the compression and decompression phases must be able to be carried out with minimum effort nonetheless guaranteeing stability during use.
 The “Passage Point” “stress”
 To ensure that the lower edge buckles before the upper edge buckles, and to avoid hysteresis events, it is necessary to optimize the stress of the edges.
 In compression:
 Lower: The projection of the lower edge towards a virtual point located on the horizontal starting from the apexes, represents with the radius of this same edge on the horizontal, the value of the stress.
 The stress of β must not exceed about 22%+− about 1% of the dimension of the lower edge.
 The stress of β must be between about 21 and about 23% of I (dimension of the lower edge).
 The stress of α must be greater than that of β. If the reverse occurs, it is the upper edge which will tend to deform first. In order that only the lower edge compresses, it is necessary to ensure that the stress of the upper edge is greater than that of the lower edge.
 Nonetheless the gap between the two stresses must be reduced. To this end, the stress β would have to be greater than or equal to about 60% of the stress of α. Below about 60% a high energy deployment problem is encountered. A stress of β=47% of the stress of α translates, for example, into an excessively hard manipulation.
 e.g.: Upper stress 2.9 mm
 Lower stress 2.0 mm
 Furthermore, when the stress of β is greater than about 70% of the stress of α, the bellows has a shape memory producing the effect of hysteresis. The closer the angle β to the straight line which starts from the apexes, the easier the compression on account of the fact that the stress of the lower edge is closer to its projection and, therefore, the stress is closer to 0. This condition is obtained with an angle of about 25° and below. But with this value, retention of liquid in the spiral tracks may be observed. Reliability and reproducibility of capacity is, therefore, lost.
 To improve compaction or miniaturization of the feeding bottle, the lower edge must represent in dimension at least about 80% of the dimension of the upper edge.
 The lower edge may, therefore, be from about 80% to about 100% of the dimension of the upper edge. If this value is exceeded, the feeding bottle becomes, after compression, an upturned conical component. This value is preferably between about 80% and about 95%.
 The feeding bottle is made up of spiral tracks each representing an effective volume of 30 ml. The upper lenticular element (10) is extended by a threaded cylindrical part (11). The total height of the corrugated part is 127.6 mm in the deployed position. It has volume calibrated calibration marks (12). Retractability is obtained preferentially by pressures along alternate oblique axes, and not along one axial direction.
 A pressure movement is exerted with lateral dissymmetry to force tilting of one side of a lenticular element, then a second pressure is exerted with an opposite lateral component to complete the compression of this first lenticular element.
 This alternate movement is then continued until the compression is obtained of the requisite number of lenticular elements. The feeding bottle then remains in a stable intermediate position.
 The material selected is here polypropylene with a modulus of about 950 Mpa for its greater resistance to heat, necessary when heating the feeding bottle and for its transparency making it possible to see the formation of lumps from powdered milk, and lastly for its rigidity necessary for the proper handling and stability of the feeding bottle.