Patent ID: 8419278
Filing Date: 2013-04-16
Classification: B65D,Y10T

Abstract:
1. A check valve comprising two valve films of synthetic resin that are placed one on the other and bonded at parts thereof together, thereby forming an air passage that allows to pass air through the valve films from an inlet to an outlet, the air passage being closable by the valve films that closely contact together, wherein the air passage is defined by two seal sections, comprising a first side seal section and a second side seal section, formed by bonding the valve films together, the inlet of the air passage being defined by a straight line linking respective upward flow side end sections of the seal sections, while the outlet of the air passage being defined by a straight line linking respective downward flow side end sections of the seal sections, and at least the downward flow side end sections of the second side seal section of the two seal sections, and downward flow side edges of the valve films are separated, wherein a passage extension section is provided on the downward flow side of the air passage, the passage extension section being defined by the outlet of the air passage, the downward flow side edges of the valve films, and a virtual line, the virtual line linking at least the downward flow side end section of the second side seal section of the two seal sections, and the downward flow side edges of the valve films, and at the virtual line, the valve films are not bonded together, and air in the air passage flows out of the valve films through the passage extension section from the outlet, wherein the check valve further comprises a non-sealed section comprising the passage extension section and a free section, the free section being adjacent to the passage extension section or to the air passage and the passage extension section, the passage extension section and the free section being bounded by the line of extension that defines the passage extension section, wherein the portions of valve film constituting the passage extension section and the free section form a single body, wherein the first side seal section is provided with an introduction section on the upward flow side and an expulsion section on the downward flow side, the expulsion section being extended in a lateral direction so as to approach to the second side seal section, and the expulsion section is formed at a front edge of the first side seal section and prevents an inverse flow of air from entering the air passage, wherein the second side seal section is provided with three sections that are an introduction section, an intermediate section, and an expulsion section, the intermediate section connecting between the introduction section and the expulsion section, and wherein, regarding the second side seal section, the intermediate section is formed closer to the first side seal section than the introduction section, further the expulsion section being formed closer to the first side seal section than the intermediate section, wherein the inlet of the air passage is defined by the upward flow side end section of the introduction section and the upward flow side end section of the first side seal section, while the outlet of the air passage is defined by the downward flow side end section of the introduction section and the downward flow side end section of the first side seal section, and wherein the downward flow side end section of the second side seal section is formed further towards the upward flow side than the downward flow side end section of the first side seal section.