Abs device for a hydraulic braking system of a cycle or a motorcycle, particularly for a bicycle

ABS device for a hydraulic braking system of a bicycle, comprising:

• an inlet, to be hydraulically connected to a master cylinder associated with a brake lever,
• an outlet, to be hydraulically connected to an actuator cylinder associated with a brake device,
• a first hydraulic line connecting said inlet to said outlet,
• an electrically operated valve, which is normally open, interposed in the first hydraulic line,
• a fluid accumulator, having an accumulation chamber defined by a movable member within a cavity, said movable member being normally in a starting position corresponding to a minimum volume of the accumulation chamber,
• a second hydraulic line connecting the accumulation chamber to said outlet,
• an electric actuator associated with the movable member of the fluid accumulator, and
• an electronic controller configured to detect an activation condition in which an activation of an ABS function is required and which, in said activation condition, is further configured to switch said electrically operated valve to a closed condition and to enable a movement of the movable member of the fluid accumulator in a direction corresponding to an increase in the volume of the accumulation chamber, so as to cause a decrease in the pressure in the second hydraulic line,
• wherein no electrically operated valve is interposed in said second hydraulic line, between the fluid accumulator and said outlet,
• said electronic controller and said electric actuator of the movable member of the fluid accumulator configured in such a way that:
• when the ABS function is activated, the electronic controller controls, through the electric actuator, a displacement of the movable member, so as to cause a progressive and continuous, substantially linear, decrease of the pressure in the second hydraulic line which in use communicates with the actuator cylinder of the brake device,
• when the ABS function is no longer required, the return of the movable member of the fluid accumulator to the starting position is anyway positively controlled by the electronic controller, through said electric actuator, in such a way as to cause a progressive and continuous, substantially linear, increase of the pressure in the second hydraulic line which in use communicates with the actuator cylinder of the brake device.