Patent ID: 8689680

Claim:
A cookware having a double-layered wall structure, comprising: a container comprising an inner shell ( 2 ) and an outer shell ( 3 ), wherein a cavity ( 4 ) is provided between said inner shell ( 2 ) and said outer shell ( 3 ), wherein upper parts of the inner shell and outer shell are rolled a predetermined number of times together to form a rolled joint ( 6 ), wherein an upper part of the inner shell ( 2 ) is provided with a concave member ( 7 ), wherein a heat transfer medium ( 8 ) is provided within said cavity ( 4 ), wherein a first heat transfer member ( 10 ) is inserted and installed at the bottom portion of said cavity ( 4 ), and wherein a second heat transfer member ( 12 ) is affixed to the bottom surface of the first heat transfer member ( 10 ); an inner cover ( 30 ) for covering the upper surface of the concave portion of said inner shell; an inner peripheral portion ( 36 ) provided along an edge of the inner cover ( 30 ) in the form of an inverted “L” whose inside bend forms a round portion, wherein the inner peripheral portion is made of steel material surrounded by an elastic lining material, and forms moisture sealing such that the cookware functions as a low pressure cooker and prevents vitamin loss in cooking; an outer cover ( 50 ) positioned above said inner cover ( 30 ); and pressure release devices ( 60 , 70 ) for releasing the pressure within said cavity ( 4 ) when a pressure within said cavity ( 4 ) gets larger than a predetermined reference pressure; and steam holes ( 38 ) formed on said inner cover ( 30 ) for releasing pressure built up the container ( 1 ) and liquid overflow from below to a gap between the inner cover ( 30 ) and the outer cover ( 50 ), wherein there is a downward slope from the steam holes ( 38 ) to the edge of the inner cover ( 30 ) so that, during cooking, steam gets out of the steam holes, condenses into water, and flows to the concave member to form the moisture sealing for preventing vapor steam from leaking out; wherein the elastic lining material expands during cooking so that increased adhesion and friction between the elastic lining material and the inner shell prevents the inner cover from opening when the container is pressurized during cooking.