Three-way three-position control valve having a piezoelectric or magnetostrictive actuator, and fuel-injection system comprising the aforesaid valve

An electrically or electromagnetically actuated control valve comprising three mouths and three operating positions, wherein said three mouths comprise:

• a first mouth for inlet of a working fluid;
• and
• a second mouth and a third mouth for outlet of the working fluid,
• and wherein said three operating positions comprise:
• a first operating position, in which a passage of fluid from said first mouth to said second mouth and third mouth is enabled,
• a second operating position, in which a passage of fluid from said first mouth to only one of said second and third mouths is enabled, and
• a third operating position, in which the passage of fluid from the first mouth to the second mouth and the third mouth is disabled,
• an electric or electromagnetic actuator that can be controlled to cause a switching of the valve between said operating positions,
• the control valve comprises a first valve element and a second valve element, which co-operate, respectively, with a first valve seat and a second valve seat,
• said first valve element and said first valve seat pre-arranged for controlling passage of fluid from said first mouth to said third mouth, and
• said second valve element and said second valve seat pre-arranged for adjusting passage of fluid from said first mouth to said second mouth, and
• said electric or electromagnetic actuator comprises an actuator member operatively connected to said second valve element and designed to impress on said second valve element:
• a first movement whereby said second valve element is brought into contact with said second valve seat disabling the passage of fluid from said first mouth to said second mouth and providing a switching from said first operating position to said second operating position,
• a second movement, subsequent to said first movement, whereby said second valve element moves said first valve element against said first valve seat disabling the passage of fluid from said first mouth to said third mouth and providing a switching from said second operating position to said third operating position,
• wherein during said second movement the second valve element is in contact with said second valve seat, and
• said first valve element and second valve element are coaxial and hydraulically balanced,
• said electric or electromagnetic actuator is of a type chosen between a piezoelectric actuator and a magnetostrictive actuator.