WO2001093731A1

WO2001093731A1 - Leak-proof closing system for pressure vessel with circular opening and circular lid

Info

Publication number: WO2001093731A1
Application number: PCT/IN2000/000059
Authority: WO
Inventors: Manjunath Varambally
Original assignee: Manjunath Varambally
Priority date: 2000-06-07
Filing date: 2000-06-07
Publication date: 2001-12-13
Also published as: AU1052001A

Abstract

The invention relates to positive closing arrangement for pressure vessels with a circular opening of baby and circular lid. An embodiment of the invention is represented in the Fig: 1. The outer diameter of the lid is smaller than the inner diameter of rim of the body, (typically by 0.5 mm). After placing the lid on the body, gasket (6) is shoved in to the groove (17) on the baby. Now, just a small rotation of the lid, with the help of handle (2) will cause the lid to couple with the gasket. Once the pressure inside the vessel increase, the thrust of the steam press the lid against the gasket. The increase in pressure, (within the working limits) make the coupling of the lid, body and the gasket firm and leak-proof. The existing design of pressure cooker are produced using deep drawing / spinning process and are either have less volumetric efficiency or prone to leak after some use. This invention aims at providing better volumetric efficiency on pressure cooker with positive closing system, and which can ALSO be produced using pressure die-casting process.

Description

TITLE OF INVENTION:

LEAK-PROOF CLOSING SYSTEM FOR PRESSURE NESSEL WITH CIRCULAR OPENING AND CIRCULAR LID.

TECHNICAL FIELD: This invention relates to a pressure cooker design involving the body, the lid, the gasket, the handles, the weight valve and safety plug in particular and pressure vessels employing the novel closing method disclosed herein, in general.

BACKGROUND A&T:

It has been widely known that, presently there are two systems of domestic pressure cooker closing, which constitute more than 95% of the pressure cookers manufactured all over the world. They are:

1) THE BAYONET CLOSING SYSTEM &

2) THE OVAL CLOSING SYSTEM.

The bayonet closing type pressure cookers (Ref: Fig 8) are characterized by: - A metallic cylindrical body with circular opening.

A metallic circular lid.

Clamping of lid on the body by 6-8 claws around the rim of the lid and the body. Disadvantages: - The leak-proof characteristic of the cookers is sensitive to the normal variations in the hardness/ thickness of the gasket. Hence gasket will become inefficient after some usage calling for frequent replacement of gasket.

The Oval Clamping type Pressure Cookers (Ref: Fig 9) are characterized by:

A metallic cylindrical body with oval opening. - An Oval shaped metallic lid.

A spring handle mounted on the lid.

For closing of the cooker, the lid is inserted in to the body at an angle, then twisted to bring the orientation of the lid to be in line with the opening of the body and then the spring handle of lid will be clamped to the body handle, closing the cooker.

Since the locking of the body and lid is all around the opening on the body, it is undoubtedly stronger against mechanical failures, compared to a bayonet closing cooker.

Disadvantages:

The actual usable volume of the cooker (i.e. the volume of the separators) is less than 50 % of the designated volume of the cooker. (A 10-liter cooker will have separator volume of less than 5 liters.). - Arranging of the separators inside the cooker calls for a wire rack.

Closing and opening of the cooker is tedious compared to bayonet clamping cookers.

FURTHER THE COOKERS WITH ABOVE TWO CLOSING SYSTEMS HAS FOLLOWING DISADVANTAGES IN COMMON: - Using pressure die-casting manufacturing process is NOT feasible for the reasons of design constraints/ cost considerations or both. (Note: Using die- casting process will cut down the processing cost )

Having curved-out bottom on the above cookers is technically / costwise NOT feasible. (Note: Curved out bottoms on pressure cookers, will help using the cookers for secondary cooking such as frying and preparation of dishes )

Having heat absorbing grooves on the bottom of these cookers is technically / costwise NOT feasible. (Note: Having grooves on the bottom will increase the ^' surface area and consequently, heat absorption. This will improve the thermal efficiency of the cooker system) - Require a loose bottom plate (Note: to avoid direct contact of the separator with the bottom of the cooker). The object of the present invention is to provide a pressure cooker design with circular opening and circular lid still ensuring positive leak-proof closing of the cooker, besides ensuring better volumetric and thermal efficiency. Advantages of this invention:

Compared to the Bayonet closing cookers:

The coupling of the body,- the gasket and the lid becomes stronger as the working pressure inside the cooker increases (within the limits of designated working pressure). The cooker locking is positive at the working pressure, thus there is no leakage of steam while pressure cooking. The effectiveness of locking (sealing) of the cooker is not very sensitive to the norrnal variations of hardness and dimension of the gasket (due to usage). Therefore the life of the gasket is longer.

Advantages of this invention:

Compared to the Oval closing cookers:

Separators volume is in the range of 65-70% of the volume of the cooker,

Arranging the separator inside the cooker do not require a separate wire rack, and the job is simple. - Closing and opening of the cooker is easier.

Advantages of this invention:

Compared to both the Bayonet and Oval closing systems:

The bottom of this cooker can be in curved out shape, which helps in certain kinds of cooking especially for frying of spices and preparation of secondary dishes.

Closing and opening of the cooker is easier.

Does not require a separate (loose part) bottom plate.

Suitable heat absorbing grooves are given on the bottom of the cooker, improving the efficiency of heat absorption thus improving thermal efficiency. - With the use of Pressure die-casting technique, the cost of manufacturing of the cooker comes down considerably.

Balanced short handles on either sides of the cooker, convenient to handle.

Simple and economical gasket.

The above and other features of this invention, including various novel details of construction and combination of parts will now be more clearly described with reference to accompanied drawings and pointed out in the claims. It is understood that a particular pressure cooker drawing is shown here by way of illustration only and not a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments, without departing from the scope of invention.

DISCLOSURE OF THE INVENTION: Reference is made to the accompanying drawings, in which is shown one type of illustrative embodiment of the invention, i.e. Pressure cooker from which its novel features and advantages are apparent.

In the drawings:

Fig : 1 - is the sectional front view of one form of cooker assembly, illustrative of embodiment of the invention.

Fig : 1' - Sectional front view thereof, with the lid in lowered position,

(Allowing insertion extraction of the gasket.)

Fig : 2 - Top view thereof,

Fig : 3 - Top view of gasket of the cooker thereof, 3 a - Front view thereof,

Fig : 4 - Sectional side view of the cooker,

Fig : 5 - Front view of the handle of the cooker lid thereof, 5a - Top view thereof, 5b - Side view thereof. Fig 6 - The Weight valve of the cooker thereof.

Fig 7 - The Safety plug of the cooker thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Referring to Fig. 1 it is^' seen that the illustrated cooker assembly includes a body member (9), two body handles (7) assembled on the body using screws (8). The rim (4) on the body is having a circular sector groove (17) all around on its inner side. _. The profile of the groove matches that of the profile of the gasket (6). The root diameter (17") of the groove (17) is equal to the outer diameter (d¹) of the gasket. [Refer Fig: 3 for (d'VJ

Further as seen in Fig.^' 1, The lid (3) of the cooker has an integral recess (22) that locates the lid handle (2) and also restricts it from rotating. The weight valve (1) and safety valve (21) are assembled on the lid. The rim (5) of the lid (3) has a circular sector groove (15) all around. The root diameter (15") of the groove (15) is equal to the inner diameter (d") of the gasket (6). [Refer Fig: 3 for diameter (d")j. The profile of the sector groove matches that of the profile of the gasket (6).

The outer diameter (15') of rim (5) of the lid (3) is smaller than the inner diameter (17') of the rim (4) of the body (9) by a fraction of a millimeter. (Typically by 0.5 millimeter.) Thus the lid can be freely inserted inside the body rim. The Lid (3) has gasket releasing recess (23) on its rim (5). The Floor (19) of the rim of the body has four number qf cams (13). These . cams have locator grooves (16). The Floor (20) of the rim of the lid has four number of cams (14) corresponding to the cam (13) on the body. These lid cams will slide inside the locator groove (16) on the body cams(13).

The body (9) has a curved out bottom (11) and three or four numbers of integral seating lugs (12). The body (9) has three or four numbers of nudges (10) on inside bottom, upon which rest the separators (24).

Referring to the Fig: 5, fig: 5a and fig: 5b, It is seen that the lid handle (2) is a bent metallic strip with thermal insulation caps(2') on either ends. It is also seen that the lid handle (2) is assembled on the lid (3) with the help of valve pipe (l¹) of weight valve assembly (1). (Refer fig 6: for valve pipe 1')

The gasket (6) is made up of a synthetic polymer or rubber. It has a gasket extraction flap (18).

The cooker is arranged for cooking in the following manner: (Referring to Fig: 1) . The body (9) is filled with 10-12% of volume of water. The food items to be cooked are taken in the separator (24) and this separator is placed on the nudge (10) of the cooker body. Now the lid (3) is closed on the body (9).

The gasket (6) is shoved between the rim (4) of the body and the lid (3). The gasket will snugly fit in to the groove (17) on the rim of the body. This state is illustrated in the Fig: V. Now the lid (3) is rotated by about 1/4 of a rotation using the lid handle (2). This will cause the cams (14) on the lid to ride over the locator groove (16) on cams (13) on the body. Due to this riding of cam (14) over cam (13), 1 the lid raises and couples with the gasket (6). This completes the initial closing of the cooker. This state is illustrated in Fig. 1.

Now the cooker is kept on a heat source. Once the water inside the cooker is heated and steams starts coming out of weight valve tube [refer Fig: 6 item (1')]. 5 Place the weight valve in position as shown in Fig: 1. The pressure inside the cooker gradually increases. Due to the thrust of the steam, the lid (3) press upward, against the gasket (6). Thus the whole of cooker assembly becomes completely leak proof. The pressure inside will increase upto the designated pressure (typically 1 Kgf/cm2 above the atmospheric pressure). Once the pressure crosses the designated pressure, i the steam thrust will lift the weight valve, and steam escape out of the cooker. This escaping of steam continue till the pressure inside the cooker come down to the level of designated pressure.

Safety features: (Three-way safety)

1. Weight valve: The weight valve is designed in such a way that, if the 5 pressure inside the cooker raised to the designated pressure, the weight valve is raised and the steam gush out of the cooker, until the pressure inside the cooker comes down below the designated pressure.

2. Safety Plug: The fusible plug is designed in such a way that, should the weight valve failed to function due to any reason, and pressure inside the cooker 0 raises beyond a pressure approximately 1.4-1.6 KgF/cm2 , then the fusible materiel of the safety plug melts and blows off. The steam gushes from the hole of the safety plug, and the pressure inside the cooker comes down. Causes for the malfunctioning of the weight valve should be corrected and the blown safety plug should be replaced with a good one. 5 3. Gasket Releasing System: In case both the weight valve and safety plug fail to function and pressure inside the cooker goes beyond 1.8 to 2 kgF/cm2, the gasket release system work, such that the gasket is pushed out of their normal position at 1 or 2 positions where gasket releasing recesses are provided on the lid. The built up steam gush out of these gaps thus avoiding the blasting of cooker. Once this occur, 0 it is essential to check and correct the reasons for mal-functioning of the weight valve and safety plug. Opening of the Cooker:

Once the cooker is cooled down and pressure inside the cooker comes down to normal atmospheric pressure, The lid (3) is rotated in anticlockwise direction holding the lid handle (2). This will make the lid to decouple from the "gasket (6) and ride down on the body cam (13). Once the lid is fully lowered, the gasket (6) is extracted from the groove (17) of the body by holding and pulling the gasket extraction flap (18). Once the gasket is out and away from the body of the cooker, the lid (3) is lifted out.

IT IS UNDERSTOOD THAT THE PRESENT INVENTION IS BY NO MEANS LIMITED TO THE PARTICULAR CONSTRUCTION HEREIN

DISCLOSED AND / OR SHOWN IN THE DRAWINGS, BUT ALSO CQMPRISES

ANY MODIFICATION OR EQUIVALENTS OR COROLLARIES WITHIN THE

SCOPE OF THE DISCLOSURE.

Claims

I CLAIM:

1. A pressure cooker assembly comprising of a metallic body with the circular opening and having a rim, a profile groove on the inner side of the rim, body being fitted with two handles made up of thermal insulation material, the body having a curved out bottom, with seating lugs and heat absorbing grooves on the bottom, the inside bottom of the body having supporting nudges for placing the separators, a metallic circular lid with a rim having a profile groove, the rim outer diameter being slightly less, typically by 0.5 millimeter, than the inner diameter of the rim on the body, a metallic handle aligned and assembled in the integral recess on the top of the lid, with the help of weight valve pipe, the floor of the body rim having cams with locator groove, and floor of the lid rim having corresponding cams, the lid having one or two gasket releasing recess, a safety plug and weight valve assembled on the lid and a circular gasket with a profiled cross section matching that of profile on grooves on the body rim and lid rim, and the gasket having an extraction flap. The body as in claim 1, in which said body has a circular opening and a circular rim, The rim as in claim 2 in which the rim having a profile groove all around on the inner side, The rim as in claim 2, in which the rim having a floor, The floor as in claim 4, in which there are cams with locator groove, The body as in claim 1, in which the bottom is curved out and having seating lugs, The body as in claim 1, in which the inside of the body has nudges for supporting the separators, The lid as in claim 1, in which said lid is circular and having a rim, The rim on the lid as in claim 8, in which the rim having a profile groove on the outside top edge, 0 The profile groove on the rim of the lid as in claim 9 in which there are gasket releasing recesses, The rim on the lid as in claim 8 in which the rim having a floor, The floor of the rim as in claim 1 1 in which there are cams on the floor of the rim, cams corresponding to the locator groove as in claim 5, The lid as in the claim 1, in which the lid has integral recess on the top side, The lid as in claim 1, in which the lid is assembled with a handle made up of bent metallic strip with caps made-up of thermal insulation material, and locate in to the integral recess on the lid as in claim 13, and which is assembled on the lid using the weight valve pipe. The pressure cooker assembly as in claim 1, in which the assembly has a gasket made up of flexible material, circular in shape and having a profiled cross section matching that of profile of groove on the body rim as in claim 3 and profile of groove on the lid as in claim 9, the outer diameter of the gasket being equal to the root diameter of the profile of groove on the body as in claim 3 and inner diameter of the gasket being equal to the root diameter of the profile of the groove on the lid as in claim 9, and gasket having a extraction flap.