Brake system for a motorcycle

A brake system for a motorcycle, comprising:

• a brake operation lever;
• a master cylinder operable in response to actuation of the brake operation lever;
• wheel braking mechanism operable to apply a braking force to a wheel by hydraulic pressure operation;
• a main brake line connecting the master cylinder to the wheel braking mechanism;
• a hydraulic pressure modulator operable to cause an electrically-operated actuator to generate hydraulic pressure corresponding to driving conditions and a braking operation of the vehicle, and for supplying the hydraulic pressure to the main brake line and discharging the hydraulic pressure from the main brake line, the hydraulic pressure modulator being merged and connected with the main brake line;
• an electromagnetic on-off valve which is provided in a position located toward the master cylinder from a portion in the main brake line where the main brake line and the hydraulic pressure modulator are merged and connected with each other, the electromagnetic on-off valve controlling communication and cutoff between the master cylinder and the wheel braking mechanism;
• and
• a pseudo reaction force generating apparatus for generating a pseudo reaction force against the hydraulic pressure to function on the master cylinder corresponding to an amount of operation of the brake operation lever while the electromagnetic on-off valve closes the main brake line,
• wherein the pseudo reaction force generating apparatus comprises:
• a fluid chamber for receiving hydraulic fluid which has flowed therein from the master cylinder;
• a piston which constitutes one of the walls of the fluid chamber and
• a plurality of elastic members, each elastic member of the plurality of elastic members having a unique characteristic, wherein each of the plurality of elastic members is operable to actively apply a force to the piston in a direction which causes the piston to reduce the volume of the fluid chamber during all operating conditions, and wherein the plurality of elastic members comprise both spring members having linear spring characteristics and spring members having hysteresis characteristics,
• wherein a path through which the master cylinder the pseudo reaction force generating apparatus are connected with each other is provided with a second electromagnetic on-off valve for opening and closing the path depending on driving conditions and a braking operation of the motorcycle, and
• wherein a bypass path which bypasses the second electromagnetic on-off valve is provided between the pseudo reaction force generating apparatus and the master cylinder, and the bypass path is provided with a check valve which allows hydraulic fluid to flow in a direction from the pseudo reaction force generating apparatus to the master cylinder.