TRANSMISSION DEVICE FOR TRANSMITTING INFORMATION ABOUT TIRE CONDITION AND TIRE CONDITION MONITORING SYSTEM

摘要

A tire condition monitoring system includes a transmission device, a receiving device, and a monitoring section. The transmission device includes a sensor which detects a condition of gas filled in a tire cavity area surrounded with a tire and a rim as tire information, a transmitter which wirelessly transmits the tire information, and a housing which houses the sensor and the transmitter. An opening portion of an air vent connecting an inner space of the housing and the tire cavity area is formed in a surface of the housing and the opening portion is formed on a top portion of a protruding portion protruding in one direction from the surface of the housing. An area of the opening portion of the air vent is 0.4 mm2 or smaller. Height of the protruding portion is 1 mm or greater. When a contact plane in contact with the top portion and perpendicular to a protruding direction of the protruding portion exists, an area of a contact portion between the contact plane and the top portion is not larger than 30% of the area of the opening portion.