Patent ID: 7871059

Claim:
A valve for adjusting a flow-rate of fluids and an electric motor for servo-control thereof, the valve comprising: a hermetic enclosure capsule; a valve body being fixed coaxially to said capsule and provided with intake and discharge ports; supporting means for reducing rotary friction; a rotor component of said electric motor that is supported by said supporting means within said hermetic enclosure; a screw-and-nut coupling mounted inside said rotor component; a flow control element which is restrained so as to perform only axial translational motions in a valve body and is coupled with said rotor component by way of said coupling; wherein said supporting means for reducing rotary friction supports said rotor component in a position that corresponds to a portion of the rotor component inside which said screw-and-nut coupling is provided; a cup-shaped body acting as a guide for the flow control element and as a connection between said capsule and said valve body, said flow control element being constituted by a stem with a threaded shank and an opposite needle-shaped flow control end, said stem having an alignment and rotation-preventing insert overmolded thereon proximate to said flow control end, said insert being provided with edges adapted to slide in complementarily shaped slots provided within a guiding hole formed on said cup-shaped body; and further comprising a magnetic cylindrical element being forced by interference coupling on an outside region of said tubular body, said magnetic element being adapted to be crossed by a magnetic field generated by a stator component of the motor, said rotor component being constituted by a tubular body inside which a female thread for mating with said threaded shank is formed, wherein said tubular body comprises a portion adapted to engage a corresponding coaxial hole of said magnetic cylindrical element, said tubular body portion being contoured externally so as to form three contiguous cylindrical regions a radius of which increases from an end toward a central part of the tubular body, namely a first outermost region of insertion with play for alignment during assembly, a second region of insertion with interference for engagement of the tubular body with the magnetic element, and a third region within tolerance, which is adapted to ensure coaxial mechanical and magnetic coupling.