Brake apparatus and method for controlling the brake apparatus

A brake apparatus, comprising:

• multiple wheel cylinders that apply braking forces to respective multiple wheels when being supplied with hydraulic fluid;
• multiple maintaining valves that are arranged upstream of the respective wheel cylinders in order to maintain hydraulic pressures in the respective wheel cylinders;
• pressure-regulating control valves that are arranged upstream of the multiple maintaining valves in order to control an upstream pressure which is a pressure upstream of the multiple maintaining valves, the pressure-regulating valves including a pressure-increasing linear control valve and a pressure-decreasing linear control valve;
• and
• a control unit that:
• calculates a deviation of the upstream pressure between a target upstream pressure and a measured upstream pressure,
• controls the braking forces by selecting one of multiple brake modes that include a regular brake mode in which all the maintaining valves are kept open so that the upstream pressure is supplied to the wheel cylinders and a special brake mode in which at least one of the maintaining valves is repeatedly opened and closed,
• controls the upstream pressure by switching a pressure-control mode to a pressure-regulating mode which is selected when the deviation of the upstream pressure is outside a setting range and in which the upstream pressure is controlled by opening one of the pressure-increasing linear control valve or the pressure-decreasing linear control valve and closing the other of the pressure-increasing linear control valve or the pressure-decreasing linear control valve, and
• when the special brake mode is selected, controls the upstream pressure by switching to a pressure-maintaining mode that is selected when the deviation of the upstream pressure is within the setting range,
• wherein the control unit opens one of the pressure-increasing linear control valve or the pressure-decreasing linear control valve before the pressure-control mode is switched from the pressure-maintaining mode to the pressure-regulating mode,
• wherein the control unit determines the setting range based on whether the pressure-regulating mode is a pressure-increase mode or a pressure-decrease mode, and
• wherein an upper limit of the setting range is a pressure-increase required threshold value and a lower limit of the setting range is a pressure-decrease required threshold value,
• the upper limit of the setting range for the pressure-increase mode in the regular brake mode being the same as the upper limit of the setting range for the pressure-increase mode in the special brake mode, and
• the lower limit of the setting range for the pressure-decrease mode in the regular brake mode being less than the lower limit of the setting range for the pressure-decrease mode in the special brake mode.

A method for controlling a brake apparatus which includes multiple wheel cylinders that apply braking forces to respective multiple wheels when being supplied with hydraulic fluid;

• multiple maintaining valves that are arranged upstream of the respective wheel cylinders in order to maintain hydraulic pressures in the respective wheel cylinders;
• and pressure-regulating control valves, including a pressure-increasing linear control valve and a pressure-decreasing linear control valve, that are arranged upstream of the multiple maintaining valves in order to control an upstream pressure which is a pressure upstream of the multiple maintaining valves, the method comprising:
• calculating a deviation of the upstream pressure between a target upstream pressure and a measured upstream pressure;
• selecting one of multiple brake modes that include a regular brake mode in which all the maintaining valves are kept open so that the upstream pressure is supplied to the wheel cylinders and a special brake mode in which at least one of the maintaining valves is repeatedly opened and closed;
• selecting a pressure-regulating mode in which the upstream pressure is controlled by opening one of the pressure-increasing linear control valve or the pressure-decreasing linear control valve and closing the other of the pressure-increasing linear control valve or the pressure-decreasing linear control valve, when the deviation of the upstream pressure is outside a setting range;
• selecting a pressure-maintaining mode when the special brake mode is selected and the deviation is within the setting range;
• and
• opening one of the pressure-increasing linear control valve or the pressure-decreasing linear control valve before the pressure-control mode is switched from the pressure-maintaining mode to the pressure-regulating mode,
• wherein the setting range is determined based on whether the pressure-regulating mode is a pressure-increase mode or a pressure-decrease mode, and
• wherein an upper limit of the setting range is a pressure-increase required threshold value and a lower limit of the setting range is a pressure-decrease required threshold value,
• the upper limit of the setting range for the pressure-increase mode in the regular brake mode being the same as the upper limit of the setting range for the pressure-increase mode in the special brake mode, and
• the lower limit of the setting range for the pressure-decrease mode in the regular brake mode being less than the lower limit of the setting range for the pressure-decrease mode in the special brake mode.