Hydraulic-pressure producing device and hydraulic brake system

A hydraulic brake system comprising:

• a cylinder device provided in a vehicle and comprising (a) a housing, (b) at least one pressurizing piston fluid-tightly and slidably fitted in the housing, (c) at least one front chamber respectively provided in front of the at least one pressurizing piston, and (d) a rear-force control device operable by a supply of electric power and capable of controlling a rear force that is a driving force applied from a rear side, the rear-force control device being configured to apply the rear force to one of the at least one pressurizing piston;
• a plurality of brake cylinders of a plurality of hydraulic brakes coupled to the at least one front chamber and provided respectively for a plurality of wheels of the vehicle, the plurality of brakes being configured to respectively restrain rotations of the plurality of wheels;
• a rear-force detection device configured to detect the rear force;
• and
• a liquid-leakage detection device comprising a difference-based detector configured to detect presence or absence of a liquid leakage from at least one line of at least one brake line comprising the at least one front chamber and at least one of the plurality of brake cylinders coupled to each of the at least one front chamber, the difference-based detector being configured to detect that there is a liquid leakage from the at least one line, when a state in which a subtraction value obtained by subtracting an actual rear force that is a value detected by the rear-force detection device from an estimated rear force that is an estimated value of the rear force is equal to or greater than a first malfunction determination threshold value had continued for a time equal to or greater than a first malfunction determination time, and thereafter the subtraction value has become equal to or less than a first return determination threshold value that is less than the first malfunction determination threshold value.

A hydraulic brake system comprising:

• a cylinder device provided in a vehicle and comprising (a) a housing, (b) at least one pressurizing piston fluid-tightly and slidably fitted in the housing, (c) at least one front chamber respectively provided in front of the at least one pressurizing piston, and (d) a rear-force control device operable by a supply of electric power and capable of controlling a rear force that is a driving force applied from a rear side, the rear-force control device being configured to apply the rear force to one of the at least one pressurizing piston;
• a plurality of brake cylinders of a plurality of hydraulic brakes coupled to the at least one front chamber and provided respectively for a plurality of wheels of the vehicle, the plurality of brakes being configured to respectively restrain rotations of the plurality of wheels;
• a rear-force detection device configured to detect the rear force;
• and
• a liquid-leakage detection device comprising:
• (a) a provisional liquid leakage detector configured to provisionally detect that there is a liquid leakage from at least one line of at least one brake line comprising the at least one front chamber and at least one of the plurality of brake cylinders coupled to each of the at least one front chamber, when a subtraction value obtained by subtracting an actual rear force that is a value detected by the rear-force detection device from an estimated rear force that is an estimated value of the rear force is equal to or greater than a second malfunction determination threshold value, and (b) a definite liquid leakage detector configured to definitely detect that there is the liquid leakage, when an absolute value of a difference between an actual bottoming time and an estimated bottoming time is equal to or less than a predetermined estimated validity determination value, wherein the actual bottoming time is a length of time actually required from a point in time when the liquid leakage is provisionally detected by the provisional liquid leakage detector, to a point in time when the subtraction value obtained by subtracting the actual rear force from the estimated rear force becomes equal to or less than a second return determination threshold value that is less than the second malfunction determination threshold value, and wherein the estimated bottoming time is a length of time estimated based on at least a position of the one pressurizing piston relative to the housing at the point in time when the liquid leakage is provisionally detected by the provisional liquid leakage detector, and the estimated bottoming time is a length of time from the point in time when the liquid leakage is provisionally detected to a point in time when the subtraction value becomes equal to or less than the second return determination threshold value.

A hydraulic-pressure producing device comprising:

• a cylinder device comprising (a) a housing, (b) at least one pressurizing piston fluid-tightly and slidably fitted in the housing, (c) at least one front chamber respectively provided in front of the at least one pressurizing piston, and (d) a rear-hydraulic-pressure control device comprising (i) a rear chamber provided at a rear of one of the at least one pressurizing piston and (ii) a power hydraulic pressure source operable by a supply of electric power and capable of producing a high hydraulic pressure, the rear-hydraulic-pressure control device being configured to control a hydraulic pressure in the rear chamber to bring the hydraulic pressure in the rear chamber closer to a target hydraulic pressure;
• a rear-hydraulic-pressure detection device configured to detect the hydraulic pressure in the rear chamber;
• and
• a liquid-leakage detection device configured to detect a leakage of working liquid from at least one of the at least one front chamber without based on a hydraulic pressure in the at least one front chamber when an actual rear hydraulic pressure that is a value detected by the rear-hydraulic-pressure detection device has increased at a rate equal to or greater than a set rate, from a state in which the actual rear hydraulic pressure is less than the target hydraulic pressure by a value equal to or greater than a first set value.

A hydraulic-pressure producing device comprising:

• a cylinder device comprising (a) a housing, (b) at least one pressurizing piston fluid-tightly and slidably fitted in the housing, (c) at least one front chamber respectively provided in front of the at least one pressurizing piston, and (d) a rear-hydraulic-pressure control device comprising (i) a rear chamber provided at a rear of one of the at least one pressurizing piston and (ii) a power hydraulic pressure source operable by a supply of electric power and capable of producing a high hydraulic pressure, the rear-hydraulic-pressure control device being configured to control a hydraulic pressure in the rear chamber to bring the hydraulic pressure in the rear chamber closer to a target hydraulic pressure;
• a rear-hydraulic-pressure detection device configured to detect the hydraulic pressure in the rear chamber;
• and
• a bottoming detection device configured to detect bottoming of the pressurizing piston not based on a hydraulic pressure in the at least one front chamber but based on at least one of a change in an actual rear hydraulic pressure that is a value detected by the rear-hydraulic-pressure detection device and a difference between the actual rear hydraulic pressure and the target hydraulic pressure.

A hydraulic-pressure producing device comprising:

• a cylinder device comprising (a) a housing, (b) at least one pressurizing piston fluid-tightly and slidably fitted in the housing, (c) at least one front chamber respectively provided in front of the at least one pressurizing piston, and (d) a rear-hydraulic-pressure control device comprising (i) a rear chamber provided at a rear of one of the at least one pressurizing piston and (ii) a power hydraulic pressure source operable by a supply of electric power and capable of producing a high hydraulic pressure, the rear-hydraulic-pressure control device being configured to control a hydraulic pressure in the rear chamber to bring the hydraulic pressure in the rear chamber closer to a target hydraulic pressure;
• a rear-hydraulic-pressure detection device configured to detect the hydraulic pressure in the rear chamber;
• and
• a liquid leakage detector configured to detect that there is a leakage from at least one of the at least one front chamber, without based on a hydraulic pressure in the at least one front chamber, when a state in which an actual rear hydraulic pressure that is a value detected by the rear-hydraulic-pressure detection device is less than the target hydraulic pressure by a value equal to or greater than a first set value has continued for a time equal to or greater than a set length of time.