Patent attributes
A check valve 60 is formed by a pair of the valve body portions 61. Ends of the valve body portions 61 that are close to an upper inflation portion EU are joined to a communication passage wall 51 by an outflow-side joint portion 41. Each valve body portion 61 includes a flexible portion 64 that is located in the vicinity of the outflow-side joint portion 41 and between the outflow-side joint portion 41 and a lower inflation portion EL. The front edges of the valve body portions 61 are joined to the communication passage wall 51 by a first edge joint portion 67. The first edge joint portion 67 also functions as a wall joint portion 63 that joins the communication passage walls 51 to each other. The rear ends of the valve body portions 61 are joined to each other by a second edge joint portion 68, which extends along the flowing direction of inflation gas. An auxiliary joint portion 69 is located between the first edge joint portion 67 and the second edge joint portion 68, and in the vicinity of the second edge joint portion 68. The auxiliary joint portion 69 joins the valve body portions 61 to each other. The auxiliary joint portion 69 also functions as a rigid portion 65, which is harder to flex than the flexible portion 64. The rigid portion 65 extends along the flowing direction of the inflation gas.
