Locking tongue for seat belt and seat belt device

A locking tongue for a seat belt of a vehicle, the locking tongue being operated to switch a state of a webbing that is the seat belt between an unfastened state in which the webbing is extended and a fastened state in which the webbing is folded back to form a shoulder belt and a lap belt, the locking tongue being configured such that when the webbing is in the fastened state, in a normal state, the locking tongue allows the webbing to pass therethrough, whereas in an emergency of the vehicle, the locking tongue clamps the webbing, the locking tongue comprising:

• a tongue body including a main wall, a pair of side walls, and an insertion portion,
• the main wall being positioned at a front side of the webbing when the webbing is in the unfastened state,
• the pair of side walls protruding from both end portions of the main wall in a width direction of the webbing to a back side of the webbing,
• the insertion portion extending from the main wall and being a portion to be inserted in a buckle for the seat belt;
• a clamp member that is, when the webbing is in the unfastened state, positioned at the back side of the webbing and engaged with guides that are provided on the pair of side walls, respectively, such that the clamp member is slidable in a direction toward the main wall;
• a rotating member that is rotatably supported by the pair of side walls at the back side of the webbing when the webbing is in the unfastened state, wherein when the webbing is in the fastened state, the webbing is wound around the rotating member such that the webbing is folded back to form the shoulder belt and the lap belt, and the rotating member rotates in a direction from the shoulder belt toward the lap belt to press the clamp member such that the clamp member slides in the direction toward the main wall;
• and
• an urging member that urges the clamp member in a direction away from the main wall, wherein
• in the normal state, a gap larger than a thickness of the webbing is formed between the clamp member and the main wall, and
• in the emergency of the vehicle, tension of the lap belt becomes greater than tension of the shoulder belt, causing the rotating member to rotate in the direction from the shoulder belt toward the lap belt against urging force of the urging member, such that the webbing is clamped between the clamp member and the main wall.