Abstract: A brake system includes a master cylinder configured to generate a hydraulic pressure, a primary brake actuator configured to increase and decrease the hydraulic pressure generated in the master cylinder, a secondary brake actuator connected in series with and downstream of the master cylinder and in series with and upstream of the primary brake actuator, and configured to increase and decrease the hydraulic pressure generated in the master cylinder, and at least one wheel cylinder configured to apply brake torque to a wheel of a vehicle based on the hydraulic pressure generated by the master cylinder and increased or decreased by the primary actuator or the secondary actuator. An automatic brake hold control method includes sequential performing an automatic brake hold control on at least one wheel cylinder by the primary brake actuator and then the secondary brake actuator.

Abstract: A brake hydraulic pressure control apparatus is provided with wheel cylinder pressure inference value acquisition means (step 402) for acquiring an inference value of the wheel cylinder pressure, master cylinder pressure inference value acquisition means (step 404) for acquiring an inference value of the master cylinder pressure by utilizing a wheel cylinder pressure inference initial value, reaction force compensation amount acquisition means (step 406) for acquiring a reaction force compensation amount which is a value depending on the variation of the master cylinder pressure caused by the flowing of brake fluid during an ABS control, and differential pressure inference value acquisition means (step 410) for acquiring an inference value of the differential pressure between the master cylinder pressure and the wheel cylinder pressure by adding the reaction force compensation amount to the difference between the master cylinder pressure inference value and the wheel cylinder pressure inference value.

Abstract: A brake hydraulic pressure control apparatus is provided with wheel cylinder pressure inference value acquisition means (step 402) for acquiring an inference value of the wheel cylinder pressure, master cylinder pressure inference value acquisition means (step 404) for acquiring an inference value of the master cylinder pressure by utilizing a wheel cylinder pressure inference initial value, reaction force compensation amount acquisition means (step 406) for acquiring a reaction force compensation amount which is a value depending on the variation of the master cylinder pressure caused by the flowing of brake fluid during an ABS control, and differential pressure inference value acquisition means (step 410) for acquiring an inference value of the differential pressure between the master cylinder pressure and the wheel cylinder pressure by adding the reaction force compensation amount to the difference between the master cylinder pressure inference value and the wheel cylinder pressure inference value.

Abstract: A newly obtained wheel speed of a drive wheel is not used in a calculation for acceleration slip when a vehicle is stopped, for example, when the wheel speed of a rolling wheel is zero and an engine speed is high. A wheel speed calculated before a previous wheel speed is, for example, set as a current wheel speed. In this manner, even if the wheel speed of a driving wheel is due to the effect of racing noise, it is possible to limit erroneous determinations that indicate acceleration slip is being generated, based upon such a wheel speed. In addition, unnecessary execution of a traction control can also be curbed.

Abstract: A vehicle speed is obtained from detection signals obtained from wheel speed sensors. In a case where a vehicle speed calculation is shifted from a first method to a second method, a vehicle speed displayed on a speedometer is gradually changed from the vehicle speed obtained by the first method to the vehicle speed obtained by the second method. This avoids abrupt change in the displayed vehicle speed causing the driver to feel discomfort.

Abstract: In a speedometer control system having wheel speed sensors as well as a vehicle speed sensor, both a PCM and a brake ECU are used to obtain vehicle speeds. Then, a signal corresponding to a vehicle speed is obtained basically from the PCM. However, if it is impossible to properly obtain a signal corresponding to a vehicle speed from the PCM, a signal corresponding to a vehicle speed is obtained from the brake ECU. Accordingly, even in the event that a signal corresponding to the vehicle speed is not obtained from the PCM, it is possible to obtain a signal corresponding to the vehicle speed from the brake ECU, and thus to display the vehicle speed on a speedometer.

Abstract: Numbers of teeth of respective rotors are obtained once and stored in an EEPROM. Then, when an ignition switch is initially turned on, vehicle wheel speeds for the respective vehicle wheels are derived based on the information about the numbers of teeth stored in the EEPROM. Accordingly, it is possible to obtain the vehicle wheel speeds even during a calculation period while the number of teeth of each rotor is being calculated each time the ignition switch is turned on. Further, it also becomes possible to perform ABS control prior to when the vehicle wheel speed calculation is completed.

Abstract: Numbers of teeth of respective rotors are obtained once and stored in an EEPROM. Then, when an ignition switch is initially turned on, vehicle wheel speeds for the respective vehicle wheels are derived based on the information about the numbers of teeth stored in the EEPROM. Accordingly, it is possible to obtain the vehicle wheel speeds even during a calculation period while the number of teeth of each rotor is being calculated each time the ignition switch is turned on. Further, it also becomes possible to perform ABS control prior to when the vehicle wheel speed calculation is completed.

Abstract: In a speedometer control system having wheel speed sensors as well as a vehicle speed sensor, both a PCM and a brake ECU are used to obtain vehicle speeds. Then, a signal corresponding to a vehicle speed is obtained basically from the PCM. However, if it is impossible to properly obtain a signal corresponding to a vehicle speed from the PCM, a signal corresponding to a vehicle speed is obtained from the brake ECU. Accordingly, even in the event that a signal corresponding to the vehicle speed is not obtained from the PCM, it is possible to obtain a signal corresponding to the vehicle speed from the brake ECU, and thus to display the vehicle speed on a speedometer.

Abstract: A vehicle speed is obtained from detection signals obtained from wheel speed sensors. In a case where a vehicle speed calculation is shifted from a first method to a second method, a vehicle speed displayed on a speedometer is gradually changed from the vehicle speed obtained by the first method to the vehicle speed obtained by the second method. This avoids abrupt change in the displayed vehicle speed causing the driver to feel discomfort.

Abstract: A newly obtained wheel speed of a drive wheel is not used in a calculation for acceleration slip when a vehicle is stopped, for example, when the wheel speed of a rolling wheel is zero and an engine speed is high. A wheel speed calculated before a previous wheel speed is, for example, set as a current wheel speed. In this manner, even if the wheel speed of a driving wheel is due to the effect of racing noise, it is possible to limit erroneous determinations that indicate acceleration slip is being generated, based upon such a wheel speed. In addition, unnecessary execution of a traction control can also be curbed.