Device for controlling the filling of a cistern

A device for controlling filling of a cistern to be installed in a main reservoir of a toilet flushing system, the device comprising:

• a valve controlling a water inlet;
• a float controlling closure of said valve, said float being movable from a high position to a low position, and inversely, said float being contained in a float housing and ensuring closing of said valve when the float housing is full in the high position, and its opening when the float housing is empty in the low position, said float housing being connected to the main reservoir by at least one siphon including two tubes, a suction tube connected to the float housing and a discharge tube connected to the main reservoir and ending into an auxiliary reservoir that ends into the volume of said main reservoir, the two tubes being connected together at the level of their upper end by a passage located above the maximum filling level of said float housing;
• and
• a control mechanism provided with means for priming said siphon that are movable from an initial position to an actuated position, and inversely, wherein said discharge tube ends into an auxiliary reservoir that ends into the volume of said main reservoir, wherein a control mechanism shift from said initial position to said actuated position results in an overpressure in said tubes, while the shift from the actuated position to the initial position results in a negative pressure, wherein successively said overpressure and said negative pressure cause water to rise to the passage and result in overflowing of said auxiliary reservoir, a flow of water from the suction tube to the discharge tube by siphoning, and thus the emptying of the float housing, a volume of injected air being sufficient to expel a portion of the air at the base of one of the tubes.