US 5,281,094 A · Electromechanical apparatus for varying blade of variable-pitch fan blades

Abstract

Blade pitch of variable pitch blades is changed by an actuator having first and second ac machines. The first ac machine is excited with ac power to apply a motoring torque to a control shaft of the actuator, thereby causing blade pitch to change in one direction. The second ac machine is excited with appropriate power to apply a braking torque to the control shaft, thereby causing blade pitch to change in an opposite direction. When the second ac machine is an induction machine, dc excitation will brake the control shaft. When the second ac machine is a synchronous machine, an ac excitation causing a retarding magnetic field will brake the control shaft.

Claims18

Dependent claims

Apparatus for torquing a control shaft of a blade pitch actuator for variable-pitch blades, comprising:

means for providing a first excitation when blade pitch is to be changed in one direction and for providing a second excitation when blade pitch is to be changed in an opposite direction;
a first ac machine for applying a motoring torque to said control shaft in response to said first excitation;
and
a second ac machine for applying a braking torque to said control shaft in response to said second excitation.

1 more element

Dependencies are inferred from the claim text.

Electromechanical apparatus for varying blade of variable-pitch fan blades

Life of this patent

Electromechanical apparatus for varying blade of variable-pitch fan blades

Life of this patent

Abstract

Claims18