Replacement necessity determination device for snap-in valve

A replacement necessity determination device for a snap-in valve, the snap-in valve including a valve stem having a tube shape, and an elastic body covering the valve stem, the snap-in valve being inserted into a hole formed in a wheel configured to hold a tire, and the snap-in valve being mounted to the wheel such that the elastic body is compressed between the valve stem and the wheel, the replacement necessity determination device comprising:

• an air pressure detection device fixed to an inner end of the snap-in valve and positioned in an air chamber formed by the wheel and the tire, the air pressure detection device including:
• an air pressure sensor configured to detect a pressure in the air chamber;
• an acceleration sensor configured to detect an acceleration of the wheel in a radial direction of the wheel;
• and
• a transmitter configured to wirelessly transmit a signal representing the pressure detected by the air pressure sensor and a signal representing the acceleration detected by the acceleration sensor;
• and
• a processor configured to:
• receive at least the signal representing the acceleration from the transmitter;
• acquire information on a rotational speed of the wheel;
• predict, based on the rotational speed and the acceleration of the wheel, a change of an angle of the snap-in valve with respect to the wheel, the change of the angle being generated in the radial direction by an elastic deformation of the elastic body from a position of the snap-in valve with respect to the wheel in response to the rotational speed of the wheel being at a reference rotational speed;
• calculate a degradation indication value of the elastic body based on a maximum value of the change of the angle in a time period set in advance when the wheel is rotating at a higher rotational speed than the reference rotational speed;
• calculate an integrated value of the degradation indication value;
• determine that the snap-in valve needs to be replaced in response to the integrated value being higher than an alarm reference value set in advance;
• and
• generate and output an alarm to notify a user that the snap-in valve needs to be replaced.