Method and apparatus for detecting tire having decreased internal pressure, and program for detecting tire having decreased internal pressure

An apparatus for detecting a tire having a decreased internal pressure by making a relative comparison among wheel speeds of tires attached to respective wheels of a vehicle, comprising:

• a wheel rotation information detection device configured to detect wheel rotation information regarding the respective tires of the vehicle;
• a wheel speed calculation device configured to calculate wheel speeds based on the wheel rotation information detected by the wheel rotation information detection device;
• a determination value calculation device configured to calculate DEL2 as a decreased pressure determination value by comparison between a front wheel speed and a rear wheel speed;
• and
• a determination device configured to determine, when the resultant decreased pressure determination value exceeds a predetermined threshold value, that a tire has a decreased internal pressure,
• wherein the apparatus further comprises a threshold value setting device configured to set the predetermined threshold value based on,
• (a) a relation obtained in advance, depending on a difference of the mass of the vehicle, between DEL2 and a load sensitivity during a vehicle turning, and
• (b) the load sensitivity obtained by a turning at the time of determination.

A computer program product embodied on a non-transitory computer readable medium for detecting a tire having a decreased internal pressure for causing, in order to detect a tire having a decreased internal pressure by making a relative comparison among wheel speeds of tires attached to respective wheels of a vehicle, a computer to perform the steps of:

• calculating wheel speeds based on wheel rotation information of the respective tires of the vehicle;
• calculating DEL2 as a decreased pressure determination value by comparison between a front wheel speed and a rear wheel speed;
• a determining, when the resultant decreased pressure determination value exceeds a predetermined threshold value, that a tire has a decreased internal pressure, and
• setting the predetermined threshold value based on
• (a) a relation obtained in advance, depending on a difference of the mass of the vehicle, between DEL2 and a load sensitivity during a vehicle turning, and
• (b) the load sensitivity obtained by a turning at the time of determination.