Braking force distribution control system for vehicle

A braking force distribution control system for a vehicle having front and rear wheels, comprising:

• a front wheel brake for exhibiting a braking force corresponding to a braking liquid pressure;
• a rear wheel brake for exhibiting a braking force corresponding to a braking liquid pressure;
• a front wheel rotational speed sensor for detecting a front wheel rotational speed;
• a rear wheel rotational speed sensor for detecting a rear wheel rotational speed;
• a front wheel speed calculating means for calculating a front wheel speed based on the front wheel rotational speed detected by said front wheel rotational speed sensor and based on a front wheel diameter;
• a rear wheel speed calculating means for calculating a rear wheel speed based on the rear wheel rotational speed detected by said rear wheel rotational speed sensor and based on a rear wheel diameter;
• braking pressure regulating means for regulating a ratio of the braking liquid pressure for the front and rear wheels;
• control quantity calculating means for calculating a control quantity for the braking pressure regulating means based on comparison of the front and rear wheel speeds calculated in said front and rear wheel speed calculating means;
• correcting-factor calculating means for calculation a correcting factor corresponding to a difference between a preset wheel diameter and an actual wheel diameter, based on a ratio of the front and rear wheel rotational speeds detected by said front and rear wheel rotational speed sensors;
• wheel speed correcting means for correcting at least one of the front and rear wheel speeds calculated by said front and rear wheel speed calculating means prior to the calculation of the control quantity by said control quantity calculating means;
• and
• control determining means for determining whether a range of variation in the correcting factor calculated by said correcting factor calculating means is equal to or larger than a preset value, and for outputting a signal indicative of a command to prohibit the calculation of the control quantity based on comparison of the front and rear wheel speeds in said control quantity calculating means when the range of variation in the correcting factor is equal to or larger than the preset value.