Abstract: A vehicle body communication device (200) transmits a request signal to both a wheel side sensor (31) that is provided in a valve (24) of a wheel (22), and a tire side sensor (32) that is embedded in a tire tread (28). When the wheel side sensor (31) and the tire side sensor (32) receive the request signal from the vehicle body communication device (200), respective return signals are transmitted to the vehicle body communication device (200). The respective transmission patterns are set to be different.

Abstract: A vehicle body communication device (200) transmits a request signal to both a wheel side sensor (31) that is provided in a valve (24) of a wheel (22), and a tire side sensor (32) that is embedded in a tire tread (28). When the wheel side sensor (31) and the tire side sensor (32) receive the request signal from the vehicle body communication device (200), respective return signals are transmitted to the vehicle body communication device (200). The respective transmission patterns are set to be different.

Abstract: A vehicle wheel speed is calculated based on a vehicle wheel speed signal outputted from a vehicle wheel speed sensor and a change width w which is an amplitude of a time change component of the calculated vehicle wheel speed. When the calculated change width w is equal to or more than a reference value w0 it is judged that a quick tire deformation is currently generated and a driver of the vehicle is informed of the quick deformation by actuating a warning device.

Abstract: A tire air pressure detection device includes an ideal driving status calculating portion (3e) and a rotational status value compensating portion (3f). The ideal driving status calculating portion calculates an ideal status value (?id) corresponding to a slip value under an ideal driving status without tire slippage. The rational status value compensating portion calculates and ideal rotational status value under the ideal driving status without tire slip based on the regression line calculated by a regression line calculating portion (3d) and the ideal slip status value calculated by the ideal driving status calculating portion.

Abstract: A vehicle wheel speed is calculated based on a vehicle wheel speed signal outputted from a vehicle wheel speed sensor and a change width w which is an amplitude of a time change component of the calculated vehicle wheel speed. When the calculated change width w is equal to or more than a reference value w0 it is judged that a quick tire deformation is currently generated and a driver of the vehicle is informed of the quick deformation by actuating a warning device.

Abstract: A tire air pressure detection device includes an ideal driving status calculating portion (3e) and a rotational status value compensating portion (3f). The ideal driving status calculating portion calculates an ideal status value (&bgr;id) corresponding to a slip value under an ideal driving status without tire slippage. The rational status value compensating portion calculates and ideal rotational status value under the ideal driving status without tire slip based on the regression line calculated by a regression line calculating portion (3d) and the ideal slip status value calculated by the ideal driving status calculating portion.

Abstract: A variable value (dynamic load radial deviation &bgr;) for making determination of a tire air pressure is calculated from pulse number cumulative values PFL, PFR, PRL and PRR that are cumulated for individual wheels when a predetermined condition is fulfilled. The calculated variable value is stored as a reference variable value, and a speed of a vehicle at the time when the reference variable value is calculated is stored as a reference vehicle speed associated with the reference variable value. If the value is newly calculated, it is determined whether or not a vehicle speed at that moment is within a predetermined vehicle speed range determined by the reference vehicle speed. If it is determined that the vehicle speed is within the predetermined vehicle speed range, it is determined, based on a difference between the newly calculated variable value and the reference variable value associated with the reference vehicle speed, whether or not the tire air pressure is normal.

Abstract: A variable value (dynamic load radial deviation &bgr;) for making determination of a tire air pressure is calculated from pulse number cumulative values PFL, PFR, PRL and PRR that are cumulated for individual wheels when a predetermined condition is fulfilled. The calculated variable value is stored as a reference variable value, and a speed of a vehicle at the time when the reference variable value is calculated is stored as a reference vehicle speed associated with the reference variable value. If the value is newly calculated, it is determined whether or not a vehicle speed at that moment is within a predetermined vehicle speed range determined by the reference vehicle speed. If it is determined that the vehicle speed is within the predetermined vehicle speed range, it is determined, based on a difference between the newly calculated variable value and the reference variable value associated with the reference vehicle speed, whether or not the tire air pressure is normal.

Abstract: A return-m-neutral mechanism for a rear wheel steering device for an electronically controlled four wheel steering vehicle, in which a spring provided in the return-to-neutral mechanism does not come into operation within a predetermined steering angle range corresponding to the most frequent occurrences in actual application, thereby achieving energy saving and improving response characteristics. In the return-to-neutral mechanism for the rear wheel steering device for restoring the steered rear wheel to its neutral position under the biasing force of the spring, a dead zone corresponding to a predetermined steering angle of the rear wheels is provided for the spring.