Bistable electric valve, in particular for a system for recovering petrol vapours in a motor vehicle

A bistable electric valve for a system for recovering petrol vapours in a motor vehicle, comprising:

• a hollow housing in which there is defined a chamber having first and second openings;
• a main obturator made of ferromagnetic material, arranged inside said chamber and displaceable between first and second working positions in which it respectively closes and opens said first opening for enabling and disabling respectively a flow of fluid from the second opening to the first opening, the main obturator having at least one calibrated through-hole for establishing communication between the region upstream and the region downstream of said obturator;
• first and second permanent magnets mounted in said housing in the vicinity of said first and second openings , respectively, and designed to keep the main obturator in the first and second working positions, respectively;
• an auxiliary obturator mounted movable in the region comprised between the main obturator and said second opening, upstream of the through-hole of the main obturator, between first and second positions in which it closes and opens said through-hole, respectively;
• a third permanent magnet, integral with the auxiliary obturator;
• and
• a control solenoid arranged around the path of the main obturator and the auxiliary obturator and configured to generate a magnetic flux tending to cause the attraction of the main obturator and the auxiliary obturator toward one or other of said first and second openings,
• wherein when the control solenoid is de-energized the electric valve assumes a first stable condition, in which the auxiliary obturator closes the through-hole of the main obturator, and the main obturator is arranged in said first working position in which it closes said first opening, or a second stable condition, in which the main obturator is in the second working condition in which it opens said first opening,
• wherein when the control solenoid is energized while the electric valve is in said first stable condition, the magnetic flux generated by the solenoid causes the third permanent magnet and the auxiliary obturator to pass into said second condition in which the auxiliary obturator opens the through-hole of the main obturator, and thereafter the main obturator to pass into the second position and the auxiliary obturator to return into its first position, and
• wherein when the solenoid is energized while the electric valve is in the second stable condition, the magnetic flux generated by the solenoid causes the main obturator and the auxiliary obturator to return into the respective first positions.