WO2001006901A1

WO2001006901A1 - Safety device for excess pressure in a pressure cooker with manhole

Info

Publication number: WO2001006901A1
Application number: PCT/FR2000/002093
Authority: WO
Inventors: Didier Louis Auguste Manchon; Carine Ginda
Original assignee: Seb S.A.
Priority date: 1999-07-23
Filing date: 2000-07-21
Publication date: 2001-02-01
Also published as: FR2796542A1; CN1361671A; EP1202657A1; AU7005100A; BR0012690B1; BR0012690A; AR030027A1; CN1139351C; FR2796542B1

Abstract

The invention concerns a safety device for excess pressure in a pressure cooker with manhole comprising a cooking vessel (1), with an opening defined by a recessed rim (4) wherein can be inserted a lid (10) to close the vessel (1) tightly via a sealing joint (11), sealingly applied against the recessed rim (4). The invention is characterised in that the joint (11) and the recessed rim (4) are so shaped that, in case of excess pressure, the lid (10) is urged into a stop position against the recessed rim (4) by one or several sector(s) of the curled edge (13, 13B), while leaving the joint (11) free to be locally deformed.

Description

OVERPRESSURE SAFETY DEVICE FOR A MANHOLE PRESSURE COOKER

TECHNICAL AREA

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

The present invention relates to an overpressure safety device for a pressure cooker with a manhole comprising a cooking vessel with an opening delimited by a reentrant rim into which a lid can be inserted to seal the vessel hermetically. intermediate a seal mounted in a substantially peripheral groove of the cover forming a rolled edge, said seal thus coming into leaktight abutment against the reentrant rim of the tank.

PRIOR ART

Pressure cookers known as "manhole" or even with a tuck-in lid are widely known and have a number of advantages, in particular those relating to their simplicity and economy of manufacture, leading to the production of particularly simple and inexpensive products.

Pressure cookers with a manhole are, as is well known to those skilled in the art, pressure cookers whose bowl and cover have a slightly oval shape allowing the cover to be inserted at the interior of the tank to come occupy, by means of a seal, and after rotation and fitting of the cover in the tank, a sealed closing position in which the rolled edge of the cover is at inside the tank, the seal being interposed between the rolled edge and the peripheral re-entrant edge of the tank.

It is already known to equip pressure cookers with a manhole of overpressure safety devices, the best known and most used overpressure safety devices among the latter generally being made up of a fusible safety device.

It is generally a piece or patch of thermoplastic material fixed to the cover, for example by screwing. In the event of an abnormal rise in temperature and overpressure, the tablet or the piece of thermoplastic material is caused to melt and then eject from the cover, thus allowing the excess pressure to escape. The parts in thermoplastic material can be replaced by fusible safety devices made from easily fusible metal parts.

The systems known to date implementing fusible security do not perfectly fulfill the security function assigned to them and suffer from certain drawbacks. In particular, it was noted that during the ejection of the pellet, the vapor projections remained relatively large, and potentially dangerous due to the rapidity of tripping of the fuse and the absence of protection at the level of the upper part. pressure cooker.

Furthermore, it turns out that the level of thermal tripping and pressure of the fuses 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 safeties was generally relatively low, which was detrimental to their effectiveness, certain users then having a tendency, by noting the systematic triggering of these safeties during unintentional dry heatings. , to permanently eliminate these safety measures by replacing the fuse with a nail or a metal part, resulting in a device devoid of safety device.

In the absence of any safety system, pressure cookers with a manhole therefore prove to be extremely dangerous since in the event of overpressure, such cooking appliances are destroyed by explosion, which makes them excessively dangerous even when 'due to their low cost, they are extremely widespread in certain regions of the world.

STATEMENT OF THE INVENTION

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

Another object of the invention is to propose a new overpressure safety device for a manhole pressure cooker allowing normal reuse of the appliance after an abnormal overpressure cycle which has caused the triggering of the overpressure device.

Another object of the invention is to propose a new overpressure safety device having excellent efficiency in terms of its safety while being of particularly simple design. Another object of the invention is to propose a new safety device avoiding any risk of improper handling, modification or improper assembly of the elements making it up.

A complementary object of the invention aims to propose a new safety device making it possible to avoid mounting inappropriate parts in the device

The objects assigned to the invention also aim to propose a new safety seal specially shaped to ensure safety at the overpressure of a pressure cooker and prevent its destruction

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

The objects assigned to the invention are also achieved using a seal intended to be mounted and used in a safety device to the overpressure for a pressure cooker with a manhole comprising at least one zone of weakening of its section to favor its local deformation.

SUMMARY OF DRAWINGS

The objects assigned to the invention will be explained in more detail on reading the description which follows with the aid of the appended drawings below, given purely by way of non-limiting illustration, in which:

- Figure 1 shows in a longitudinal cross sectional view, 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 an operating situation without overpressure.

- Figure 3 illustrates in a view identical to Figure 2, a detail of the safety device according to the invention in an overpressure situation.

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

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

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

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

BEST WAY TO IMPLEMENT THE INVENTION

FIG. 1 illustrates in general a pressure cooker with a manhole comprising a cooking tank 1 made of metallic material, with a bottom 2 from which rise the walls 3, substantially vertical, of the tank, the latter being surmounted by a re-entrant edge 4 extending over the entire periphery of the tank 1.

The opening of the tank, of substantially oval shape, is delimited by the terminal edge 5 of the re-entrant flange 4.

As is well known to a person skilled in the art, within the meaning of the invention, a re-entrant flange 4 means the upper annular end portion of the tank 1 directed towards the axis of symmetry S of the tank whatever or the angular value of the re-entrant flange 4 relative to a horizontal plane, the re-entrant flange 4 therefore overhanging part of the bottom 2.

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

Thanks to 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 tank 1 at its outer periphery, by means of a handle (not shown). , by tilting it slightly and inserting it through the largest opening of the tank, then making the oval of the cover 10 coincide with the oval of the tank 1 by rotation to an angular value of approximately 90 degrees . In the closed position illustrated in FIGS. 1 to 3, the cover 10 is held against the re-entrant flange 4 by means of the upper part of the seal 11 which comes into sealing abutment against the re-entering edge 4 by means of the re-pressing of a tank handle and a cover handle not shown in the figures.

As is particularly visible in FIGS. 2 and 3, the groove 12 delimited externally by the rolled edge 13 includes an internal edge 13A and an external edge 13B forming the rolled edge proper and intended to come into abutment against the internal face of the edge re-entering 4 by its upper end 13C as illustrated in FIG. 3, in the event of overpressure. In the stop position illustrated in FIG. 3, the rolled edge 13B, according to its geometric configuration, comes into abutment 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 flange 4 are shaped, so that in the event of overpressure, the cover 10 comes into abutment position against the re-entrant flange 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 to deform locally 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 clearance zone (s) formed outside the contact sector (s) so as to locally break the seal and allow the pressure to escape between the re-entrant rim 4, that is to say between the end edge 5, and the cover 10.

According to the invention, the concept of "overpressure" means a state of pressure internal to the pressure cooker, greater than the normal operating pressure, and for example greater than 0.9 bars.

According to the invention, the clearance zone (s) which is (are) formed outside the sector (s) of contact with the returning edge 4 is (are) advantageously produced (s) in the form simple local deformations of drilling (s), cutout (s) or notch (s) 15 (FIG. 4) formed or made in the rolled edge 13B over a certain height from the end 13C, and at intervals regular or not. Thanks to this arrangement, it is thus possible to release a part of the lateral surface of the seal 11 so as 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 locally break at the level of the notch (s) 15. Depending on the dimensional dimensions chosen, of the seal 11, of the re-entrant edge 4 and of the cover 10, all or part of the seal 11 may locally at the level of the notch (s) 15 disappear, that is to say leave its sealing contact by simple creep or else move locally, or even more or less partially extrude between the terminal edge 5 and the cover 10.

In a particularly advantageous manner, an effort will be made to facilitate the displacement or the centripetal deformation of the seal 11, taking care to create sufficient space for the displacement of the seal 11 at the interface between the side 10B of the cover 10 and the end edge. 5 of the re-entrant edge 4. Thus, as is particularly visible in FIG. 2, that the safety device according to the invention may advantageously comprise on an angular sector substantially aligned with the clearance zone or zones corresponding to the notches 15, a localized clearance L situated on at least one annular sector between the side 10B of the cover 10 and the re-entrant 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 clearance 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 alternative embodiment, the localization deformation (s) is (are) formed by a counter 20 (Figure 4) formed from the outer face of the cover 10 in line with a notch 15. Such local deformation can be obtained in a particularly simple manner by forming during the stamping operation of the cover. Other forms and ways of obtaining a local deformation of the cover are obviously conceivable as soon as one succeeds in obtaining a local rupture of the general shape of the sidewall 10B located at right or in radial alignment with a notch 15 allowing an increase in the leakage space of the seal 11 in the centripetal direction.

In a particularly advantageous manner, the safety device according to the invention will comprise a pair of notches 15 of any shape and for example in diametrically opposite arc of a circle and situated at the level of the small width of the substantially oval opening of the tank. 1.

In the same way, as a variant, it is obviously conceivable to produce the clearance area (s) in the form of an opening or of a bore made in the re-entrant edge 4 situated at the right of the annular zone against which the seal 11 comes to rest in the sealing position.

In the exemplary embodiments illustrated in FIGS. 2 and 3, the rolled edge 13B has a substantially planar 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 mastery of movement of the seal 11 out of the groove 12 in a substantially internal radial direction or even centripetal by providing for a seal 11 comprising 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 seal 11, so that the zone or zones of weakness 30 of the section of the seal 11 can be substantially radially aligned at the level or zones (s) of clearance of the cover 10, that is to say at the level of the notches 15 and of the counter 20, to favor the local deformation of said seal.

Thanks to such a modification of the local resistance of the seal 11 at the clearance zones, the seal 11 can deform locally in the centripetal direction at a level of overpressure substantially lower than the level of overpressure required for a displacement or an 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 joint, only over a portion of its height and its thickness. As shown in particular in Figure 7, the interior recess

31 may be a recess of shape substantially comparable to a rectangle quadrilateral, it being understood that any other geometric form of possible internal weakening is also possible.

In a particularly advantageous manner, the weakening zone 30 can be made even more sensitive to deformation by associating the internal recess 31 with an external recess 32, aligned radially with the internal recess 31. According to a possible alternative embodiment such that 'illustrated in Figure 7, the outer recess 32 may be formed by an outer recess 32 of shape substantially equivalent to the inner recess 31, but of smaller size, formed in the upper part of the joint. The external recess 32 can be completed by a complementary external recess 32A produced in the form of a substantially concave cutout extending over the entire height of the seal 11. Obviously, as a variant, a seal according to the invention could be provided with one or more weakening zones comprising an internal recess 31 or an external recess 32 or a combination of the two.

As a preferred variant, the seal 11 according to the invention and intended for use in a device according to the invention will preferably comprise two weakening zones 30 diametrically opposite and preferably arranged at the level of the small width of the seal oval 11.

According to the invention, the means for indexing the position of the seal are advantageously produced in the form of an internal bead 35, for example hemispherical, projecting radially from the internal blank of the seal and by a corresponding housing (not shown in the figures) of conjugate shape provided on the cover 10 at the level of the groove 12. Other types of indexing means can obviously be envisaged 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 seal 11. The presence of the upper peripheral rib 36 has the advantage of improving the total tightness of the seal without reducing its propensity to centripetal deformation in the event of overpressure.

It is also conceivable to improve and / or facilitate the movement of the seal 11 and therefore, overall, to improve the safety of the device by making the re-entrant edge 4 inclined beyond the horizontal plane by an angle α preferably d 'about 25 degrees. The production of an inclined re-entrant edge 4 makes it possible, in the event of overpressure, to avoid jamming of the seal 11 between the end 13C (FIG. 2) and said re-entrant edge 4 while allowing or at least promoting the displacement of the seal 11 in internal or centripetal radial direction precisely due to the inclination. In general, such an inclination makes it possible to reduce the mechanical stresses occurring in the event of overpressure.

By way of a particularly advantageous variant, it is also advantageous to stiffen the outer edge 13B of the rolled edge 13 in order to avoid any deformation or crushing of said rolled edge when the end 13C comes into contact with the re-entrant edge 4. In fact if such a deformation took place the seal 11 could be pinched between the rolled edge 13 and the re-entrant edge 4 which would prevent its centripetal displacement. To this end, the outer edge 13B will see its mechanical strength reinforced, its height h (FIG. 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. Compliance with the length relationships mentioned above makes it possible to sufficiently stiffen the rolled edge 13 to avoid its deformation and thus preserve the centripetal displacement of the seal 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 a manhole, avoiding any passage of pressure from the interior of the tank 1 towards the exterior of the pressure cooker. In the event of abnormal overpressure, and insofar as the other safety devices annexed to the pressure cooker (pressure relief valve for example) have not previously functioned, the cover 10 comes into contact via the end upper 13C of the rolled edge 13B with the internal face of the re-entrant edge 4 (FIG. 3). Such a situation generally occurs towards a pressure zone close to 1.7 bars approximately.

In this situation, the upper end 13C comes into mechanical abutment against the internal face of the re-entrant edge 4, the notches 15 then leaving sufficient space by which the pressure can push the seal 11 in the centripetal direction out of the groove 12. According to the chosen configuration mode, the seal 11 can then either be locally extruded by sliding and accompanying it out of the groove 12 in the counter 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 moving, the seal 11 can of course be replaced and reused normally.

POSSIBILITY OF INDUSTRIAL APPLICATION The invention finds its industrial application in the manufacture of pressure cookers with a manhole and in the manufacture of safety seals intended to be mounted and used in such pressure cookers.

Claims

- Overpressure safety device for a pressure cooker with a manhole comprising a cooking vessel (1), with an opening delimited by a re-entrant flange (4) into which a lid (10) can be inserted to close hermetically the tank (1) by means of a seal (11), mounted in a groove (12), substantially peripheral of the cover (10) forming a rolled edge (13, 13B), said seal (11 ), thus coming into sealed contact against the re-entrant flange (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 the position of abutment against the re-entrant flange (4) by one or more sector (s) of the periphery of the rolled edge (13, 13B), while leaving the seal (11) free to deform locally in a substantially centripetal direction under the effect of the pressure acting through one or more clearance zones (s) outside the or sectors (s) so as to locally break the seal and allow steam to escape between the re-entrant flange (4) and the cover (10).

- Device according to claim 1 characterized in that it comprises a localized clearance (L) located on at least one annular sector between the cover (10) and the re-entrant edge (4), said localized clearance being greater than the average peripheral clearance ( 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 level of the localized clearance (L).

- Device according to claim 2 characterized in that the localized clearance (L) is formed by at least one local deformation of the cover (10). - Device according to claim 3 characterized in that the local deformation (s) is (are) formed (s) by a counter (20), formed from the outer face of the cover (10).

- Device according to one of claims 1 to 4 characterized in that the rolled edge (13, 13B) has a terminal end (13C) substantially planar, the zone or zones (s) of clearance being formed (s) each by a hole or a notch (15), formed (e) substantially at said terminal end (13C).

- Device according to claim 5 characterized in that the drilling or the notch (15) is produced (e) substantially in line with each local deformation.

- Device according to claims 5 or 6 characterized in that the zone or zones (s) of clearance is (are) formed (s) by a pair of opposite notches (15) located at the level of the small width of the opening of the tank (1).

- Device according to one of claims 1 to 7 characterized in that it is provided with means for indexing the position of the seal (11), said seal comprising at least one weakening zone (30) of its section at level of the clearance zone (s) to promote its local deformation.

- Device according to claim 8 characterized in that the weakening zone is formed by an internal recess (31) formed in the upper part of the seal (11). - Device according to claims 8 or 9 characterized in that the weakening zone (30) is formed by an external recess (32) formed in the upper part of the seal (11).

- Device according to one of claims 1 to 10 characterized in that the seal is provided with an upper peripheral rib (36) surmounting the rest of the body of the seal (11).

- Device according to one of claims 8 to 11, characterized in that the indexing means are formed by at least one internal bead (35) projecting radially from the joint and by a corresponding housing of conjugate shape, formed on the cover (10).

- Device according to one of claims 1 to 12 characterized in that the re-entrant edge (4) is inclined beyond the horizontal plane, preferably about 25 °.

- Manhole pressure cooker equipped with a device according to one of claims 1 to 13.

-Seal seal intended to be mounted and used in a safety device for overpressure for a pressure cooker with a manhole according to one of claims 1 to 13.

-Seal according to claim 15 characterized in that it comprises at least one weakening zone (30) of its section to promote its local deformation. -Gasket according to claim 16 characterized in that the weakening zone (30) is formed by an internal recess (31) formed in the upper part of the seal (11).

-Joint according to claim 16 or 17 characterized in that the weakening zone (30) is formed by an external recess (32) formed in the upper part of the joint (11).

-Joint according to one of claims 16 to 18 characterized in that it is provided with an upper peripheral rib (36) surmounting the rest of the body of the seal (11).

-Joint according to one of claims 16 to 19 characterized in that it comprises an indexing means (35) of its position.