Title of Invention

A SAFETY SYSTEM FOR A PRESSURE COOKER

Abstract ABSTRACT A safety system for a pressure cooker comprising a steam pressure release device and amanally operable taper face lever; a tubular portion terminating at one end in a hollow collar, the mouth at the base of the hollow collar being closed by a fusible plug; a sealing ring provided around the tubular portion at the junction of the tubular portion and the collar, said ring having a circumference larger than that of the aperture, but smaller than or substantially the same as that of the collar, said tubular portion, up to the other end thereof, being provided with through-slits on its side, the throgh-slits terminating in a contoured flared head having a circumference just larger than that of the aperture; the said lever being provided with a
Full Text

This invention relates to a safety system for a pressure cooker.'
An objective of the system proposed herein is to close an aperture in the lid of the pressure cooker under increasing steam pressure build-up, at the start of the cooking operation; to release steam, even after full steam pressure build-up, whenever the user wishes to open the lid; to prevent the lid of the pressure cooker being opened until the steam pressure within the cooker has reached a safe value.
The system proposed herein also has a provision to let out steam in a one-shot operation, in the event of excessive build-up of pressure. This may happen, for instance, when the pressure release weight valve of the cooker malfunctions.
The system proposed herein is simple in its construction, yet quick and efficient in operation, as will be clear from the following further description thereof given hereunder.
Various other advantageous features of this invention

will also be apparent from such description.
The safety system for a pressure cooker, according to this invention, comprises a steam pressure release device and a manually operable taper face lever, the said device being insertable into an aperture on the lid of the cooker, the device comprising a tubular portion terminating at one end in a hollow collar, the circumference of the tubular portion being smaller than that of the aperture and the circumference of the collar being larger than that of the aperture, the mouth at the base of the hollow collar being closed by a fusible plug; a sealing ring provided around the tubular portion at the junction of the tubular portion and the collar, said ring having a circumference larger than that of the aperture, but smaller than or substantially the same as that of the collar, said tubular portion, up to the other end thereof, being provided with through-slits on its side, the through-slits terminating in a contoured flared head having a circumference just larger than that of the aperture; the said lever being provided with a catch for locking and unlocking the lid and bowl in the first and second

extreme positions of the lever, respectively, the taper face of the lever coming into slide-contact with the said head and thereby progressively depressing the same as the lever is moved from the first to the second extreme position; a ridge provided on the taper face butting against the said head during movement of the lever from the first to the second position, and thus arresting such movement, until the the said head descends below the ridge, on partial depletion of steam pressure in the bowl, the said ridge and taper face during, and upon, completion of movement of the lever to the second extreme position, maintaining the said head depressed, until the lever is reverted to its first extreme position.
The system proposed herein will now be described in
greater detail by referring to the accompanying
drawings which illustrate, by way of example, and not
by way of limitation, one of various possible
embodiments of this invention, wherein
Figs.lA and IB illustrate the device
Fig.2 illustrates the device located in the aperture

of the lid of a pressure cooker, closing the aperture
fully
Fig.3 illustrates the device located in the aperture of
the lid of the cooker, opening the aperture
Fig.4 illustrates the lever with taper face, knob,
shaft and catch
Fig.5 illustrates the taper face in slide-contact with
the head of the device and the ridge
and
Figs.6 to 8 illustrate three positions of the taper
face as it moves from first extreme position to second
extreme position of the lever.
The device is intended for insertion into an aperture A in the lid L of a pressure cooker. The insertion is effected from the underside of the lid L.
The device comprises a tubular portion T. At one end, the said tubular portion terminates in a hollow collar C, the circumference of which is larger than that of the aperture A. The circumference of the tubular portion T is however smaller than that of the aperture A.
t

As already stated, the collar C is hollow; however, the mouth of the hollow at the base of the collar is closed by a fusible plug P made of a material such as tin-bismuth alloy. This plug would fuse (melt) under excessive steam pressure in the bowl of the pressure cooker, corresponding to a predetermined temperature, and thus open the said mouth to release steam from the bowl, in a one-shot operation. The steam escapes through the hollow of the collar, passes through, and around, the tubular portion T and thence to atmosphere, to relieve the bowl of such pressure. Such a situation of build-up of excessive pressure would arise when the pressure release weight valve, with which a pressure cooker is normally equipped, fails to function.
A sealing ring S is provided around the tubular portion T at the junction J thereof and the collar C. The circumference of the sealing ring S is larger than that of the aperture A, but smaller than or substantially the same as that of the collar C.
The tubular portion T is provided with through-slits Y on its sides terminating at the other end thereof in a

flared head F of circumference just larger than that of the aperture A. The flared head F is contoured at Z, to furnish an outward bulge.
To install the device, the head F is pushed into the aperture A from the underside of the lid L. Although the head F has a larger circumference than that of the aperture A, the through-slits Y on the head F and the contour (outward bulge) at Z of the said head permit the said head F to contract, under resilience, when thrust against the aperture A, to reduce itself in circumference and enter the aperture A.
Once the head F passes through the aperture A, it resumes its normal circumference, which is larger than that of the aperture A, thus preventing itself from coming out of the aperture A, unless forcefully tugged out of the aperture.
With the device inserted into the aperture A in the lid, as aforesaid, and with the lid L closed over the bowl of the pressure cooker, the steam, initially generated within the bowl, passes through the aperture A to atmosphere inasmuch as the collar C and sealing

ring S dangle from the aperture A and therefore do not fully close the said aperture. Further build-up of steam within the bowl causes the collar C and sealing ring S to urge themselves against the aperture A and fully close it, thus allowing normal steam pressure build-up to take place within the bowl.
Whenever the pressure cooker is in use, the user can release steam pressure from the bowl by depressing the flared head F, even under conditions of full steam pressure build-up in the bowl. Depression of the head F causes the collar C to descend into the bowl, opening the aperture A in the lid, permitting steam from the bowl to enter the aperture A, pass through, and around, the tubular portion T and thence to atmosphere.
It is preferred to have the head F accommodated within the top handle of the pressure cooker, with an orifice provided in the handle, for allowing escaping steam to emerge through the said orifice, to atmosphere. To a substantial extent this would identify the escape route of steam and minimise the possibility of the user being inadvertently scalded. Additionally, the handle in

which the head F would be accommodated would serve to shield the user from the said device.
In the preferred arrangement wherein the head F is accommodated within the top handle of the pressure cooker, depression of the head F is conveniently achieved by means of a lever.
Conventionally, whenever the user intends to open the lid of the pressure cooker, when there is already steam pressure build-up in the bowl, a crude makeshift instrument, such as a knife or a screwdriver, is made use of to lift the weight valve. Frequently, the weight valve is sought to be lifted by hand using a piece of cloth to grip the hot top end of the weight. These crude methods are eliminated by the system proposed herein.
The lever 1 comprised in the system proposed herein is provided with a catch 2 for locking and unlocking the lid L and the bowl of the pressure cooker. The lever 1 is pivotably mounted within the top handle 3 of the cooker and is manually operable by the knob 4 outside

the handle and on its surface. As the lever is manually rotated, by operating the knob 4, the catch 2 is also rotated. In the first extreme position of the lever corresponding to the knob position 5, the catch protrudes beyond the inner periphery on the underside of the lid L to butt against a flange of the bowl and thus lock the lid and bowl. In the other extreme position of the lever corresponding to the knob position 6, the catch 2 retracts into the top handle 3 to unlock the lid from the bowl.
As the knob 4 is turned from its first extreme position towards the second extreme position, a taper face 7 provided for the lever comes into slide-contact with the head F of the device and thereby pogressively depresses the same.
A ridge 8 is provided on the taper face 7 and as the taper face moves in slide-contact with the head, the ridge butts against the said head and thus arrests any further movement of the taper face 7. Meanwhile, as the head is depressed by the taper face 7 of the lever, the aperture A is opened to let out steam. An orifice 9

passing through the top handle 3 and located above the head F lets out the steam to atmosphere.
As the pressure of steam in the bowl gets depleted to a safe value, the head F descends below the ridge 8, thus permitting the taper face 7 to be moved further to the second extreme position of the lever corresponding to the knob position 6. In this position of the lever, the catch 2 retracts to unlock the lid from the bowl and enable the cooker to be opened. The catch 2 is mounted on a shaft 10 attached to the lever 1.
The taper face 7 of the lever has an opening 10 which aligns itself with the head F whenever the ridge 8 butts against it. The escaping steam passes through this opening and the orifice 9 to atmosphere as the head gets depressed by the taper face 7.
The terms and expressions in this specification are of description and not of limitation, as such terms and expressions do not exclude any equivalents of the features illustrated and described, but various other embodiments of this invention are possible without


departing from the scope and ambit thereof. We Claim:
1. A safety system for a pressure cooker comprising a steam pressure release device and a manually operable taper face lever, the said device being insertable into an aperture on the lid of the cooker, the device comprising a tubular portion terminating at one end in a hollow collar, the circumference of the tubular portion being smaller than that of the aperture and the circumference of the collar being larger than that of the aperture, the mouth at the base of the hollow collar being closed by a fusible plug; a sealing ring provided around the tubular portion at the junction of the tubular portion and the collar, said ring having a circumference larger than that of the aperture, but smaller than or substantially the same as that of the collar, said tubular portion, up to the other end thereof, being provided with through-slits on its side, the through-slits terminating in a contoured flared head having a circumference just larger than that of the aperture; the said lever being provided with a

catch for locking and unlocking the lid and bowl in the first and second extreme positions of the lever, respectively, the taper face of the lever coming into slide-contact with the said head and thereby progressively depressing the same as the lever is moved from the first to the second extreme position; a ridge provided on the taper face butting against the said head during movement of the lever from the first to the second position, and thus arresting such movement, until the the said head descends below the ridge, on partial depletion of steam pressure in the bowl, the said ridge and taper face during, and upon, completion of movement of the lever to the second extreme position, maintaining the said head depressed, until the lever is reverted to its first extreme position.
2. A safety system as claimed in Claim 1 wherein the lever is mounted within the top handle and is provided with a rotatable knob outside, and on the surface of, the said handle.
3. A safety system as claimed in any one of the preceding Claims wherein the lever has an opening on

its tapered face aligning with the said head whenever the ridge butts against the said head.
5. A safety system as claimed in any one of the
preceding Claims wherein a steam outlet orifice is
provided through the top handle above the said head
for the escape of steam therethrough.
6. A safety presure system for a pressure cooker
substantially as herein described and illustrated in
the accompanying drawings.


Documents:

0558-mas-2001 abstract duplicate.pdf

0558-mas-2001 abstract.pdf

0558-mas-2001 claims duplicate.pdf

0558-mas-2001 claims.pdf

0558-mas-2001 correspondence others.pdf

0558-mas-2001 correspondence po.pdf

0558-mas-2001 description (complete) duplicate.pdf

0558-mas-2001 description (complete).pdf

0558-mas-2001 drawings duplicate.pdf

0558-mas-2001 drawings.pdf

0558-mas-2001 form-1.pdf

0558-mas-2001 form-19.pdf

0558-mas-2001 form-26.pdf


Patent Number 198839
Indian Patent Application Number 558/MAS/2001
PG Journal Number 08/2007
Publication Date 23-Feb-2007
Grant Date 21-Feb-2006
Date of Filing 06-Jul-2001
Name of Patentee TTK PRESTIGE LIMITED,
Applicant Address TTK PRESTIGE LIMITED, 11TH FLOOR, BRIGADE TOWERS, 135, BRIGADE ROAD, BANGALORE-560 025
Inventors:
# Inventor's Name Inventor's Address
1 TIRUVALLUR THATTAI JAGANNATHAN , CHAIRMAN TTK PRESTIGE LIMITED, 11TH FLOOR, BRIGADE TOWERS, 135, BRIGADE ROAD, BANGALORE-560 025
2 JANAKIRAMAN MANJUNATH GENERAL MANAGER-PRODUCT DEVELOPMENT ,TTK PRESTIGE LIMITED, 11TH FLOOR, BRIGADE TOWERS, 135, BRIGADE ROAD, BANGALORE-560 025
3 SHIMOGGA GANESH RAO JAYANTHA MANAGER-PROJECT DEVELOPMENT , TTK PRESTIGE LIMITED, 11TH FLOOR, BRIGADE TOWERS, 135, BRIGADE ROAD, BANGALORE-560 025
PCT International Classification Number A47J27/092
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA