Title of Invention

A PRESSURIZED COOKER

Abstract This invention provides a pressurized cooker comprising a vessel and a lid, characterized in that said lid is provided with an opening and means are provided for fitting a resilient plate made of a material such as rubber over the said opening, said means for fitting the said plate comprises a cap capable of being applied against the said plate towards the periphery of the latter on to the edges of said opening on the cooker, the base of the said cap is provided with an opening or is positioned spaced from the said plate with means provided for the space between the cap and the plate to communicate with the interior of the cooker when the cap is fitted internally or with the exterior when the cap is fitted externally.
Full Text

This invention relates to a pressure cooker or a pressure sterilizer. More particularly this invention relates to an additional safety device which would prevent an accidental explosion of the pressure cooker or pressure sterilizer.
The invention is aimed principally at and would be described with reference to pressure cookers, ^ But it can also be applied to pressure sterilizers, the vent weight or a spring biased safety valve for' letting out excess steam within the cooker can get stuck. The fusible alloy pellet safety valve can also fail in some cases particularly when it is a spurious one. Pressure cooker explosions do occur causing injury to the operator. It is against this background that in-built safety devices have been thought of and proposed by many. Thus Indian Patent No.149522 proposes a gasket release system (GRS) for the lid outside the body type of pressure cookers. The value of this GRS has been well recognised and the invention adopted by several manufacturers. But a not so well recognised defect of these lid outside the body type of pressure cookers with a GRS is that leaks are frequent at the safety slot on the lid during the routine working of the appliance (with the weight valve functioning adequately) especially with an aging gasket as the gasket is not supported adequately at the slot. But the safety feature is of supreme importance and this has avoided many a pressure cooker explosion in these
lid outside the body type of pressure cookers. The GRS is however not available for the lid inside the body type of pressure cookers.

A safety feature related to such a narrow ring as the gasket may not function 9. properly at the crucial moment. The allowable width of the gasket and consequently of the slot on the lid is a limiting factor for pressure release mechanisms related to the gasket and this severely limits its use particularly for the lid inside the body type of pressure cookers. As such the need is felt for an extra safety device which does not predispose to leaks during the routine functioning of the cooker but which becomes operative when the pressure reaches dangerous levels. Certain pressure cookers of the prior art do have a small hole on their lid fitted with a rubber disc cap having a biflanged edge which engages on to the edge of the said hole on the lid. The centre of this rubber disc cap is provided with a fusible alloy pellet. In case the alloy pellet does not melt the rubber disc cap would be ejected out of the lid when the pressure reaches dangerous levels. Besides the possibility of leakage at the edges of the rubber disc cap during routine working, the main defect of this existing safety valve is that the size of the hole on the lid of the cooker cannot be increased as the rubber disc cap would then be ejected out during the routine working of the cooker. Such a small rubber cap sealing a small hole may not be ejected out at the critical moment and the failed ejection mm mechanism may predispose to an explosion. The object of this invention is to propose a pressure release mechanism independent of the gasket, which does not predispose to leaks during the routine working of the cooker but becomes unfailingly operative when the pressure reaches dangerous levels, which can be put into practice economically

and which can be applied to both the lid outside and lid inside the body type of pressure cookers.
Accordingly this invention provides a pressure cooker or
a pressure sterilizer hereinafter referred to as 'the cooker*
comprising a vessel and a lid with means provided for sealingly
fitting the said lid on to the mouth of the vessel through a gasket
and a safety valve for letting out the steam as and when the x
pressure goes above a predetermined value characterised in that
or
said vessel above and away from its base or the said lid is
provided with an opening and means are provided for sealingly
fitting a resilient plate made of a material such as
rubber over the said opening, said means comprises a cap with means
provided for applying said cap against the said opening on the
cooker so as to hold the said plate between the cap and the
*
cooker against the said opening on the cooker, said cap capable of being applied against the said plate towards the periphery of the latter on to the edges of said opening on the cooker in the fitted position of the cap and the plate on the cooker so as to provide a leak proof fitting, and means provided for the said plate to communicate with the interior of the cooker and with the exterior (at least potentially) through the body wall of the cooker.
The means of communication of the resilient plate with
the interior or exterior of the cooker is as follows: The

base of the cap (applied over or under the resilient plate )

is provied with an opening and/or the base of the said cap is
spacedly positioned from the said plate and means are provided for the space between the cap and the plate to communicate with the interior of the cooker (when the cap is fitted internally), or with the exterior, at least potentially, when the cap is fitted externally. In the preferred embodiments the body of the cooker towards its top or the said lid of the cooker is provided with an outwardly or inwardly extending tubular projection so as to hold the said plate between the said cap and the said tubular projection. From the manufacturing point of view it is economical if the lid of the cooker is provided with an opening and an externally threaded tubular bolt with an outward flange towards its one end and an internally threaded nut dimensioned to be fitted over the said tubular bolt so as to grip the lid of the cooker in between at the edges of
said opening on the said lid is also provided. A cap with a base

and an internally threaded skirt extending from the base, said skirt of the cap being dimensioned to fit against the said externally threaded tubular bolt would hold the said plate between the cap and the said tubular bolt. The base of the cap may be provided with a central opening exposing internally or externally the central part of the plate through the said opening. Alternatively the base of the cap is spaced ly positioned from the said plate, said skirt having an inwardly extending step dimensioned to fit over the peripheral edge of the said plate all

around, the space between the said cap and the said plate communi-
eating with the interior or exterior of the cooker through an
opening provided on the said cap. The preferred form of the said
plate a rubber
disc and this may be made of the same material that goes into the making of the gasket of the cooker.
The Invention will now be described with reference to the accompanying drawings, wherein: Fig.1: is the sectional elevation of the part of the lid of
the cooker provided with one embodiment of the extra
safety valve according to the invention; Fig.2: is the sectional elevation of the part of the lid of
the cooker provided with another embodiment of the extra
safety valve according to the invention; Fig,3: is the sectional elevation of the part of the
lid of the cooker provided with another embodiment of the
extra safety valve according to the invention.
As shown in the figures, the lid L of the pressure cooker
is provided with an opening. An externally threaded tubular bolt
B with an outward flange F towards its bottom and an internally
threaded JocfafiiiaKxfcaE nut N dimensioned to be fitted over the said
externally threaded tubular bolt so as to grip the lid of the cooker
of the
in between at the edges^ttia said opening on the said lid L is provided. A metal cap C with a base and an internally threaded skirt

extending downwards from the base, said skirt being dimensioned to fit against the said externally threaded bolt is also provided, said base of the cap C being provided with an opening P. The tubular bolt B has an inwardly extending annular projection defining a mouth M against which the rubber is placed. The rubber disk K may be made of the same type of heat stable rubber which goes into the making of the rubber gasket of pressure cookers. In the embodiment shown in Fig. 1/ the rubber disk K is pressed all around its periphery by the holed base of the cap C when the cap is fitted on to the tubular bolt thus providing a leak proof fitting. The central

through the opening P on the metal cap C and with the exterior
through the opening M on the tubular bolt. An additional press
be
fitting cap may be. provided for fitting on the opening P (when the cap
C is fitted externally) or on the opening M (when the cap C is
fitted internally) , M and P being the external openings exposing
the rubber plate.

In the routine working of the pressure cooker the steam pushes the'rubber disc outwards, but the steam pressure would not be sufficient to rupture the stretched disc. There is thus no risk of leakage at this extra safety valve during the routine working of the cooker as the disc can be well pressed all around. But when the pressure reaches dangerous levels, the rubber disc ruptures to let out the steam and the steam escapes out through the openings M and P. A new rubber disc is inserted once the old one has ruptured and the cooker used again. In cases where the openings P or M are closed externally by a press fitting cap, this cap is ejected out by the excess pressure of steam. The size of the opening on the lid of the cooker and of the mouth M, and the sixe of the opening or of the raised portion on the base of the said cap C, and the area and thickness of the rubber disc K can be suitably adjusted so thst the disc can withstand the ordinary workiag pressures of the pressure cooker but would give way when the pressure reaches dangerous levels. The cap C also performs the aesthetic function of concealing Idwt the rubber disc from the operator. For most ordinary cookers the rubber disc is exposed for an area of at least 2 sq.cm.



I claim:
1, A pressure cooker or a pressure sxerillzer nereinatter referred to as •the cooker' comprising a vessel and a lid with means provided for sealingly fitting the said lid on to the mouth of the vessel through a gasket and a safety valve for letting out the steam as and when the pressure goes above am a predetermined value characterised in that said vessel above and away from its base or the said lid is provided with an opening and means are. provided for sealingly fitting a resilient plate made of a material such as rubber over the said opening, said means comprises a cap with means provided for applying said
cap against the said opening on the cooker so as to hold
the said plate towards the periphery of the latter on to the edges
of said opening on the cooker so as to provide a leak proof fitting,
and means provided for the said plate to communicate with the
interior of the cooker and with the exterior (at least potentially)
through the body wall of the cooker.
2. The cooker as claimed in claim 1, wherein the base of the
said cap is provided with an opening and/or
is spacedly positioned from the said plate and means are provided
for the space between the cap and the plate to communicate with
the interior of the cooker (when the cap is fitted
internally) or with the exterior when the
cap is fitted externally.

3. The cocker as claimed in claims 1 to 2, wherein said vessel above and away from its base or the said lid of the cooker is provided with an outwardly or inwardly extending tubular projection communicating with the cavity of the cooker and means are provided for fitting said cap on to the said tubular projection so as to hold the said plate between the said cap and the said tubular projection.
4. The jcboker as claimed ia claim 3, wherein said cap is fitted to the said tubular projection through threaded connections.
5. The cooker as claimed in claims 1 to 4, wherein an additional press fitting electable cap is provided for fitting on the external opening exposing the said plate.
6. The cooker as claimed in claims 1 to 5, wherein said rubber plate is exposed for an area of at least 2 sq.cm.
7. ▲ pressure cooker or a pressure sterilizer substantially as herein described with reference to, and as illustrated in, the accompanying drawings.


Documents:

426-mas-2000-abstract.pdf

426-mas-2000-claims filed.pdf

426-mas-2000-claims granted.pdf

426-mas-2000-correspondnece-others.pdf

426-mas-2000-correspondnece-po.pdf

426-mas-2000-description(complete) granted.pdf

426-mas-2000-description(complete).pdf

426-mas-2000-drawings.pdf

426-mas-2000-form 1.pdf

426-mas-2000-form 19.pdf

426-mas-2000-form 3.pdf

abs-426-mas-2000.jpg


Patent Number 210228
Indian Patent Application Number 426/MAS/2000
PG Journal Number 50/2007
Publication Date 14-Dec-2007
Grant Date 25-Sep-2007
Date of Filing 02-Jun-2000
Name of Patentee DR. JOSE THAIKATTIL
Applicant Address UNIVERSITY HEALTH CENTRE, CALICUT UNIVERSITY P.O.,
Inventors:
# Inventor's Name Inventor's Address
1 DR. JOSE THAIKATTIL UNIVERSITY HEALTH CENTRE, CALICUT UNIVERSITY P.O.,
PCT International Classification Number A47J 27/08
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA