Patent ID: 8279055

Claim:
A tire pressure monitoring system, comprising: a pressure sensor unit which is mounted on a running wheel of a vehicle and provided with a pressure sensor for detecting a pressure of a tire of the running wheel and a centrifugal force sensor for detecting a centrifugal force due to rotation of the tire; and a pressure monitoring unit to which a data containing a detection value of the pressure sensor and an identification number which is uniquely assigned to the pressure sensor unit is transmitted if a detection value of the centrifugal force sensor becomes a predetermined value and over with a frequency higher than the frequency when the detection value of the centrifugal force sensor is less than the predetermined value, and which monitors a lowering of the pressure of the tire by comparing the detection value of the pressure sensor contained in the data with a predetermined check threshold value if an identification number of the received data is identical to the identification number of the pressure sensor unit mounted on the running wheel of the vehicle, wherein a plurality of wheel sets each of which consists of a number of wheels identical to a number of the running wheels of the vehicle are prepared in the vehicle; wherein the vehicle mounts one wheel set selected as the running wheels from the plurality of the wheel sets; and wherein the pressure monitoring unit stores the identification number of the pressure sensor unit mounted on each wheel included in the plurality of wheel sets by the wheel set and identifies the identification number corresponding to the selected one wheel set as the identification number of the pressure sensor unit mounted on the running wheel of the vehicle, wherein when the vehicle is running at a predetermined speed and over and if the identification numbers contained in the data received within a predetermined time are identical to all identification numbers corresponding to another wheel set among the plurality of the wheel sets except for the one wheel set, the identification numbers corresponding to the another wheel set are newly identified as the identification numbers of the pressure sensor units mounted on the running wheels of the vehicle by replacing the identification numbers corresponding to the one wheel set.