Device for regulating the flow rate of air feeding a turbine ventilation cavity of a turbomachine turbine section

A device for regulating the flow rate of air feeding a turbine ventilation cavity of a turbomachine turbine section, comprising:

• at least one tubular duct opening out at one end into a take-off cavity communicating with a flow passage for a stream of air in a compression section of the turbomachine and leading at an opposite end into a turbine ventilation cavity that communicates with a flow passage for a gas stream in a turbine section of the turbomachine, a pressure inside the take-off cavity being higher than a pressure inside the turbine ventilation cavity;
• a flow rate regulation valve disposed in the tubular duct, the valve presenting the form of a disk centered on the longitudinal axis of the duct, being made up of two half-disks of diameters that are pivotally mounted on a rigid shaft that is secured to the duct and that extends transversely relative thereto, and being suitable for moving under the effect of a pressure difference between the take-off cavity and the turbine ventilation cavity between a maximum closure position for the duct in which the half-disks are deployed in a plane extending substantially transversely across the duct so that some non-zero minimum air flow rate passes through the valve, and a minimum closure position for the duct in which the half-disks retract into a plane lying substantially longitudinally relative to the duct so that a maximum air flow rate passes through the valve;
• mechanical return means for holding the valve in its maximum closure position for the duct so long as the pressure difference between the take-off cavity and the turbine ventilation cavity remains below a predetermined threshold pressure;
• and
• a ring mounted at the end of the duct that leads into the turbine ventilation cavity, the ring including at least one abutment that comes to bear axially against at least one of the two half-disks when the flow rate regulation valve is in its maximum closure position for the duct, said abutment being suitable for deforming under the effect of a pressure inside the turbine ventilation cavity that is higher than the pressure inside the duct so that the flow regulation valve comes into axial abutment against the ring so as to close the duct completely.