Patent ID: 7031874
Filing Date: 2006-04-18
Classification: B60T,G01P

Abstract:
1. A vehicle wheel speed calculation device comprising: a first signal detection portion for reading a first pulse signal that is generated by a first wheel speed sensor when a first rotor rotates along with a first wheel attached to a vehicle, the pulse signal according with either one of a number of teeth and a switch number of the first rotor; a second signal detection portion for reading a second pulse signal that is generated by a second wheel speed sensor when a second rotor rotates along with a second wheel attached to the vehicle, the pulse signal according with one of a number of teeth and a switch number of the second rotor; a provisional vehicle wheel speed calculation portion which assumes that the respective numbers of teeth and the switch numbers of the first rotor and the second rotor are respective predetermined numbers, and which obtains a first provisional vehicle wheel speed that is taken as a provisional wheel speed for the first wheel based on a pulse number of the first pulse signal detected by the first signal detection portion, and the respective predetermined numbers, and which obtains a second provisional vehicle wheel speed that is taken as a provisional wheel speed for the second wheel based on a pulse number of the second pulse signal detected by the first signal detection portion and the respective predetermined numbers; an estimation portion for estimating one of the respective numbers of teeth and the switch numbers of the first rotor and the second rotor based on a ratio of the first provisional vehicle wheel speed and the second provisional vehicle wheel speed; a non-volatile storage unit for storing one of the respective numbers of teeth and the switch numbers of the first rotor and the second rotor that are estimated by the estimation portion; and a vehicle wheel speed calculation portion for deriving a vehicle wheel speed of the first wheel and a vehicle wheel speed of the second wheel based on one of the respective numbers of teeth and the switch numbers for the first rotor and the second rotor stored in the non-volatile storage unit, and the respective detection results from the first signal detection portion and the second signal detection portion.