FR2796542A1 - Over pressure safety device for pressure cooker comprises seal inserted in pan re-entrant edge which is free to deform in lid rolled sectors in event of overpressure - Google Patents

Abstract

The pressure cooker lid (10) is inserted into a re-entrant edge (4) of the pan and hermetically closed with a seal (11). The seal and the re-entrant edge are shaped so that in the event of an over pressure the lid is abutted against the re-entrant edge over one or more sectors of the periphery of the rolled edge (13,13B) leaving the joint free to locally deform.

Description

The present invention relates to the technical field of safety devices with overpressure. for pressure cookers with a manhole, such devices being designed to prevent the violent spraying of steam and / or the complete destruction of the cooking apparatus in the event of overpressure.

The present invention relates to an overpressure safety device for a manhole pressure cooker comprising a cooking vessel with an opening defined by a re-entrant rim into which a lid can be inserted to seal the vessel by the intermediate of a seal mounted in a substantially peripheral groove of the lid forming a rolled edge, said seal thus bearing tightly against the recessed rim of the vessel.

The so-called pressure cookers "with manhole" or with re-entrant lid, are widely known and have a number of advantages including those relating to their simplicity of manufacturing economy leading to the realization of particularly simple and cheap products .

Pressure cookers with a manhole are, as is well known to those skilled in the art, pressure cookers whose bowl and lid have a slightly oval shape allowing the lid to be inserted inside the tank to come occupy, by means of a seal, and after rotation and placement of the lid in the tank, a sealing position in which the rolled edge of the lid is inside the tank, the seal seal being interposed between the rolled edge and the peripheral reentrant edge of the vessel.

<B> It </ B> is already known to equip pressure cookers with manholes of overpressure safety devices, the safety devices with the overpressure the most known and most used among these latter generally consisting of fusible security.

It is generally a piece or tablet made of thermoplastic material attached to the cover, for example by screwing. In the event of abnormal elevation of temperature and overpressure, the pellet, or piece of thermoplastic material is caused to melt and then eject from the lid, thus allowing the overpressure to escape. Parts made of thermoplastic material can be replaced by fusible safeties made from easily fusible metal parts.

Systems known to date implementing a fuse safety do not perfectly fulfill the safety function assigned to them and suffer from certain disadvantages. In particular, it was found that during ejection of the pellet, the vapor projections remained relatively large, and potentially dangerous because of the speed of fuse tripping and the lack of protection at the top. of the pressure cooker.

Furthermore, it turns out that the thermal tripping level and fuse pressure is excessively variable which reduces the efficiency and safety of such devices.

In addition, it has also been found that the triggering pressure of these securities was generally relatively low, which hampered their effectiveness, some users then tending, noting the systematic triggering of these securities during unintentional dry heating , to definitively eliminate these securities by replacing the fuse by a nail or a metal part, resulting in a device devoid of safety device, In the absence of any safety system, the pressure cookers with manhole are accordingly extremely dangerous since in case of overpressure, such cooking appliances are destroyed by explosion, which makes them excessively dangerous even though because of their low cost, they are extremely widespread in some parts of the world.

The objects assigned to the invention therefore aim to remedy the various disadvantages listed above and to propose a new overpressure safety device for a manhole pressure cooker whose efficiency is improved and which avoids the destruction of the in the event of overpressure.

Another object of the invention is to provide a new overpressure safety device for pressure cooker with a manhole allowing normal reuse of the device after an abnormal overpressure cycle that caused the triggering of the pressure relief device.

Another object of the invention is to provide a new overpressure safety device having excellent safety efficiency while being particularly simple design.

Another object of the invention is to propose a new security device avoiding any risk of mishandling, modification or improper assembly of the component elements. A complementary object of the invention is to propose a new safety device to avoid mounting inappropriate parts in the device.

The objects assigned to the invention are achieved by means of an overpressure safety device for a manhole pressure cooker comprising a cooking vessel with an opening delimited by a re-entrant rim in which is likely to be inserted a lid for sealing the tank by means of a seal mounted in a substantially peripheral groove of the lid forming a rolled edge, said seal thus bearing tightly against the recessed rim, characterized in that the seal and the recessed flange is shaped, so that in case of overpressure, the lid comes into abutment position against the return flange by one or more sector (s) of the periphery of the rolled edge while leaving the seal free to locally deform in substantially internal radial direction under the effect of the pressure acting through one or more zone (s) clearance (s) outside the sector (s) in order to break the seal locally and allow the steam to escape between the re-entrant rim and the cover.

The objects assigned to the invention will be explained in more detail on reading the following description with the aid of the appended drawings below, given purely by way of non-limiting illustration, in which - FIG. in longitudinal cross-section, a general view of a pressure cooker with a manhole according to the invention.

- Figure 2 illustrates in a partial cross sectional view, a detail of embodiment of the safety device according to the invention in operating situation without overpressure. - Figure 3 illustrates in a view identical to Figure 2, a detail of embodiment of the safety device according to the invention in overpressure situation.

- Figure 4 illustrates in a general perspective view, an embodiment of a manhole pressure cooker lid according to the invention.

- Figure 5 illustrates in a view from above, an embodiment of a seal according to an overpressure safety device according to the invention.

- Figure 6 illustrates in a side view, an embodiment of a seal according to an overpressure safety device according to the invention, said seal being identical to that shown in Figure 5.

- Figure 7 illustrates in a partial top view of a detail of an area of weakening of the section of a seal according to the invention.

FIG. 1 generally illustrates a pressure cooker with a manhole comprising a cooking vessel 1 made of metallic material, with a bottom 2 from which rise the walls 3, substantially vertical, of the tank, the latter being overcome by a reentrant edge 4 extending over the entire periphery of the vessel 1.

 The opening of the vessel, of substantially oval shape, is delimited by the end edge 5 of the re-entrant rim 4.

As is well known to those skilled in the art, in the sense of the invention, the term "return rim 4" is understood to mean the annular upper terminal portion of the vessel 1 directed towards the axis of symmetry S of the vessel whatever the angular value of the re-entrant flange 4 with respect to a horizontal plane, the reentrant flange 4 consequently overhanging part of the bottom 2.

The manhole pressure cooker according to the invention also comprises a lid 10 (FIG. 4), also of substantially oval shape with a curved central portion 10A and an O-flank 10B, the lid 10 being intended to be inserted into the lid. opening the cooking vessel 1 to close the latter hermetically by means of a seal 11 mounted in a substantially peripheral groove 12 of said cover 10, said groove being formed by a rolled edge 13.

With this arrangement, the seal 11 being placed in abutment at the bottom of the groove 12, the cover 10 can be inserted into the opening of the vessel 1 at its outer periphery; by means of a handle (not shown), tilting it slightly and inserting it through the larger opening of the tank, then then making the oval of the cover 10 coincide with the oval of the tank 1 by rotation on an angular value of about 90 degrees. In the closed position illustrated in FIGS. 1 to 3, the cover 10 is held against the re-entrant rim 4 by means of the upper part of the seal 11 which bears tightly against the re-entrant edge 4 thanks to the support of a bowl handle and a lid handle not shown in the figures.

As is particularly visible in Figures 2 and 3, the groove 12 externally bounded by the rolled edge 13 comprises an inner edge 13A and an outer edge 13B forming the rolled edge itself and intended to bear against the inner face of the edge entering 4 by its upper end 13C as illustrated in Figure 3, in case of overpressure. In the abutment position illustrated in FIG. 3, the rolled edge 13B, according to its geometric configuration, abuts on one or more angular sector (s) defined by the surface of the upper end 13C.

According to the invention, the seal 11 and the re-entrant rim 4 are shaped, so that in case of overpressure, the cover 10 comes into abutment position against the re-entrant rim 4 by one or more sector (s) of the periphery of the edge rolled 13, 13B defined by the surface of the upper end 13C while leaving the seal 11 locally deform in a substantially centripetal direction, in consideration of the axis of symmetry S of the cooking vessel 1, under the effect of the pressure acting through one or more zones of clearance outside the contact sector (s) so as to locally break the seal and allow the pressure to escape between the re-entrant rim 4 , ie between the terminal edge 5, and the lid 10.

According to the invention, the concept of overpressure "is understood to mean a pressure state internal to the pressure cooker, greater than the normal operating pressure, and for example greater than 0.9 bar.

According to the invention, the zone (s) of clearance which is (are) provided (s) out of the sector (s) of contact with the re-entrant edge 4 is (are) advantageously carried out (s) in the form simple local deformations of drilling (s), cut (s) or notch (s) 15 (Figure 4) formed (s) or made in the rolled edge 13B over a certain height from the end 13C, and at intervals regular or not. With this arrangement, it is thus possible to release a portion of the lateral surface of the seal 11 to allow the pressure P to be exerted directly on the seal 11 in a substantially centripetal manner as can be seen in FIG. 3, to break locally at the notch (s) 15 sealing. According to the chosen dimensional dimensions, the seal 11, the re-entrant edge 4 and the cover 10, all or part of the seal 11 may locally at the level of the notch (s) 15 to be erased, ie to leave its sealing contact. by simple creep or move locally, or even extrude more or less partially between the terminal edge 5 and the lid 10.

Particularly advantageously, efforts will be made to facilitate the displacement or the centripetal deformation of the gasket 11, taking care to create sufficient space for the displacement of the gasket 11 at the interface between the sidewall 10B of the cover 10 and the terminal edge 5 Thus, as is particularly visible in Figure 2, the safety device according to the invention may advantageously comprise an angular sector substantially aligned with the zone (s) of clearance corresponding to the notches 15, a localized clearance L located on at least one annular sector between the sidewall 10B of the cover 10 and the reentrant edge 4, said localized clearance L being greater than the average peripheral clearance M existing between the cover 10 and the re-entrant edge 4 to allow the seal 11 to extrude out of the groove 12 at said localized game L.

In a particularly advantageous manner, the localized clearance L will be formed by at least one local deformation of the cover 10. According to a first variant embodiment, the local deformation (s) is (are) formed by a counterweight. (Figure 4) formed from the outer face of the lid 10 to the right of a notch 15. Such local deformation can be obtained particularly simply by forming during the drawing operation of the lid. Other forms and ways of obtaining a local deformation of the cover are of course conceivable as soon as it is possible to obtain a local rupture of the general shape of the flank 10B located at right or in radial alignment with a notch 15 allowing an increase in the leakage gap of the seal 11 in the centripetal direction. Particularly advantageously, the safety device according to the invention will comprise a pair of notches 15 of any shape and for example in a circular arc opposite diametrically and located at the small width of the substantially oval opening of the tank 1.

In the same way, by way of a variant, it is of course conceivable to make the zone (s) of clearance in the form of an opening or a hole formed in the re-entrant edge 4 located at the right the annular zone against which rests the gasket 11 in the sealing position. In the exemplary embodiments illustrated in FIGS. 2 and 3, the rolled edge 13B has a substantially flat upper end 13C, where the clearance zone (s) are formed (each) by a notch 15 formed in the end upper 13C.

It may be particularly advantageous to improve the control and control of the displacement of the seal 11 out of the groove 12 in a substantially internal radial or centripetal direction by providing for a seal 11 having at least one weakening zone 30 of its section. . According to such an alternative embodiment, the safety device according to the invention will be provided with means for indexing the position of the gasket 11, so that the weakening zone (s) 30 of the gasket section 11 may be substantially aligned radially at the area (s) of clearance of the cover 10, that is to say at the notches 15 and against 20, to promote the local deformation of said seal. By such a modification of the local resistance of the seal 11 at the clearance zones, the seal 11 can locally deform centripetrically at a pressure level substantially lower than the level of overpressure required for a displacement or extrusion of the seal 11 without the presence of a weakening zone 30. According to a particularly advantageous variant, the weakening zone 30 is formed by an internal recess 31 formed in the upper part of the gasket, only over a portion of its height and its thickness. . As shown in particular in FIG. 7, the inner recess 31 may be a recess of substantially similar shape to a quadrilateral rectangle, it being understood that any other geometric shape of possible internal weakening is also conceivable.

Particularly advantageously, the weakening zone 30 can be made even more sensitive to deformation by associating the inner recess 31 with an outer recess 32 aligned radially with the inner recess 31. According to a possible variant embodiment such as 7, the outer recess 32 may be formed by an outer recess 32 of substantially equivalent shape to the inner recess 31, but of smaller dimension, formed in the upper part of the seal. The outer recess 32 may be completed by a complementary external recess 32A made in the form of a substantially concave cutout extending over the entire height of the gasket 11. Of course, as a variant, a gasket according to the invention could be provided with one or more weakening zones having an inner recess 31 or an outer recess 32 or a combination of both.

As a preferred variant, the gasket 11 according to the invention and intended to be used in a device according to the invention will preferably comprise two diametrically opposed weakening zones 30 and preferably arranged at the small width of the gasket. oval 11.

According to the invention, the indexing means of the position of the seal are advantageously made in the form of an internal bead 35, for example hemispherical, protruding radially from the internal blank of the seal and a corresponding housing (not shown in the figures) of conjugated form formed on the cover 10 at the groove 12. Other types of indexing means can of course be considered without departing from the scope of the invention.

According to the invention, the seal 11 may advantageously be provided with an upper peripheral rib 36 (FIG. 7), arranged for example in a substantially central manner, surmounting the rest of the body of the gasket 11. The presence of the upper peripheral rib 36 presents the advantage of improving the total seal of the seal without reducing its propensity for centripetal deformation in case of overpressure.

<B> It </ B> is also possible to improve and / or facilitate the movement of the seal 11 and therefore overall to improve the safety of the device by producing the re-entrant edge 4 in an inclined manner beyond the horizontal plane d an angle preferably has about 25 degrees. The realization of an inclined tapered edge 4 allows in case of overpressure, to avoid the jamming of the seal 11 between the end 13C (Figure 2) and said re-entrant edge 4 while allowing or at least promoting the displacement of the seal 11 in the internal radial or centripetal direction precisely because of the inclination, In general, such an inclination makes it possible to reduce the mechanical stresses occurring in the event of overpressure.

As a particularly advantageous variant it is also advantageous to stiffen the outer edge 13B of the rolled edge 13 to prevent possible deformation or crushing of said rolled edge when the end 13C comes into contact with the re-entrant edge 4. Indeed if such deformation took place the seal 11 could be pinched between the rolled edge 13 and the reentrant edge 4 which would prevent its centripetal displacement. For this purpose the outer edge 13B will have its reinforced mechanical strength, its height h (Figure 2) being advantageously between 2R and 4R, and preferably substantially equal to 3R. In this case, the height h corresponds to the height of the rolled edge 13B extending beyond the semicircle forming the bottom of the groove 12, the value R corresponding to the mean radius of the bottom of the groove 12.

The respect of the length relationships mentioned above makes it possible to sufficiently stiffen the rolled edge 13 to prevent it from being deformed and thus to preserve the centripetal displacement of the gasket 11 in the event of overpressure. The operation of the safety device according to the invention is as follows. In normal operating position, the seal 11 seals the pressure cooker with manhole, avoiding any pressure passage from the inside of the tank 1 to the outside of the pressure cooker. In the event of abnormal overpressure, and insofar as the other safety devices ancillary to the pressure cooker (pressure relief valve for example) have not previously worked, the cover 10 comes into contact via the end upper 13C rolled edge 13B with the inner face of the reentrant edge 4 (Figure 3). Such a situation usually occurs in a pressure zone of around 1.7 bars.

In this situation, the upper end 13C comes into mechanical abutment against the inner face of the re-entrant edge 4, the notches 15 leaving then a sufficient space through which the pressure can push the seal 11 in the centripetal direction out of the groove 12. According to the chosen mode of configuration, the seal 11 can then be extruded locally by sliding and accompanying out of the groove 12 in the against 20, or simply creep if the safety device is provided with a thinning zone 30. In one case as in the other the pressure can escape avoiding any explosive destruction of the pressure cooker. After its displacement, the seal 11 can of course be put back in place and reused normally.

Claims (1)

<1> - Overpressure safety device for a manhole pressure cooker comprising a cooking vessel (1), with an opening defined by a re-entrant flange (4) in which is likely to inserting a lid (10) to seal the tank (1) by means of a seal (11) mounted in a substantially peripheral groove (12) of the lid (10) forming a rolled edge ( 13, 13B), said seal (11), thereby sealingly abuts against the re-entrant rim (4), characterized in that the seal (11) and the re-entrant flange (4) are shaped so that, in the event of overpressure, the cover (10) comes into abutment position against the rim (4) by one or more sector (s) of the periphery of the rolled edge (13, 13B), while leaving the seal (11) free to locally deform in a substantially centripetal direction under the effect of pressure acting through one or more zones of discharge arranged outside the sector (s) so as to locally break the seal and allow steam to escape between the recessed rim (4) and the cover (10). 2 - Device according to claim 1 characterized in that it comprises a localized game (L) located on at least one annular sector between the cover (10) and the reentrant edge (4), said localized game being greater than the average peripheral game (M) between the cover (10) and the re-entrant edge (4) to allow the seal (11) to extrude out of the groove (12) at the localized clearance (L). 3 - Device according to claim 2 characterized in that the localized play (L) is formed by at least one local deformation of the cover (10). 4 - Device according to claim 3 characterized in that the or local deformation (s) is (are) formed (s) by a cons (20), formed from the outer face of the cover (10). 5 - Device according to one of claims 1 to 4 characterized in that the rolled edge (13, 13B) has a substantially flat end (13C), the zone or zones of release being formed (s) each by a bore or notch (15) formed substantially at said terminal end (13C). 6 - Device according to claim 5 characterized in that the bore or the notch (15) is made (e) substantially to the right of each local deformation. 7 - Device according to claims 5 or 6 characterized in that the zone (s) of clearance is (are) formed (s) by a pair of notches (15) opposite located at the small width of the opening of the tank (1). 8 - Device according to one of claims 1 to 7 characterized in that it is provided with indexing means of the position of the seal (11), said seal having at least one weakening zone (30) of its section at the level (s) of the clearance zone (s) to promote its local deformation. 9 - Device according to claim 8 characterized in that the weakening zone is formed by an inner recess (31) formed in the upper part of the seal (11). 10 - Device according to claims 8 or 9 characterized in that the weakening zone (30) is formed by an outer recess (32) formed in the upper part of the seal (11). 11 - Device according to one of claims 1 to 10 characterized in that the seal is provided with an upper peripheral rib (36) above the rest of the body of the seal (11). 12 - Device according to one of claims 8 to 11, characterized in that the indexing means are formed by at least one inner bead (35) projecting radially from the joint and a corresponding housing of conjugate form, arranged on the lid (10). 13 - Device according to one of claims 1 to 12 characterized in that the reentrant edge (4) is inclined beyond the horizontal plane, preferably about 25. 14 - Pressure cooker with a manhole equipped with a device according to one of claims 1 to 13. 15 - Seal intended to be mounted and used in a device according to one of claims 1 to 13.