Control valve with a self-compensating piezoelectric actuator

A control valve, comprising:

• a closure member movable between a valve opening work position and a valve closing rest position, and
• an actuator device, including
• a fixed portion,
• a piezoelectric actuating member having a reference portion for connection to said fixed portion and a free portion rigidly connected to the closure member and movable relative to the reference portion as a result of mechanical deformations produced in the actuating member by the piezoelectric effect,
• urging means adapted to maintain the closure member in said valve rest position when the piezoelectric actuating member is not excited, and
• locking means operable to selectively
• retain said reference portion of the actuating member in a previously determined reference position in which said reference portion is fixed firmly to said fixed portion so that excitation of the actuating member is adapted to cause actuation of the valve, or
• free said reference portion in an adjustment or tuning condition relative to the fixed portion while the actuating member is not excited so that the reference portion is allowed to reach a newly determined reference position relative to the fixed portion while said urging means keep the closure member in the valve rest position.