Safety valve

A safety valve which is mounted on a battery and operates to maintain a predetermined internal pressure in the battery when the predetermined pressure or more is applied to the battery, the safety valve comprising:

• a main body which has a hollow structure formed so that a top communicates with a bottom and a discharge hole in one side surface of an upper portion;
• a sub body which is formed to protrude from an inner circumferential surface of the main body, wherein a through hole is formed in one side surface of a lower portion of the sub body;
• a cap membrane of which a cross section has a “⊂” shape so that the cap membrane is in close contact with an upper portion of the sub body to close the upper portion of the sub body due to a weight of the cap membrane or moves upward from the upper portion of the sub body to open the upper portion of the sub body and which has a circular cap shape;
• and
• a cover which opens or closes the upper portion of the main body,
• wherein a protrusion is formed on an inner circumferential surface of an end portion of the cap membrane,
• when a pressure in the sub body is less than the predetermined pressure, the cap membrane is in close contact with the upper portion of the sub body due to the weight of the cap membrane, and the protrusion is in line contact with an outer circumferential surface of the sub body, and
• when a pressure of the sub body is greater than or equal to the predetermined pressure, the cap membrane moves upward from the sub body to open the upper portion of the sub body, and the protrusion is separated from the outer circumferential surface of the sub body, and
• wherein a hook part protruding inward along an edge of an upper surface of the cap membrane is formed, and a weight plate is seated inside the hook part.