Electrical actuator with a refined cascade control unit

Throttle device for use in an air inlet of an internal-combustion engine, which throttle device comprises a throttle valve housing, an air passage which is connectable to the air inlet, a throttle valve which is journalled in the throttle valve housing so as to be pivotable in the air passage, and an electrical actuator for pivoting the throttle valve, wherein the electrical actuator comprises

• a first actuator body,
• a second actuator body which is rotatable with respect to the first actuator body about an axis of rotation,
• means for exerting a load torque on the second actuator body, which load torque urges said second actuator body toward a rest position with respect to said first actuator body,
• electrical energizing means for exerting an electromagnetic torque on the second actuator body, said electromagnetic torque acting oppositely to said load torque to cause said second actuator body to rotate through an angle of rotation .phi. from said rest position to a desired position, said angle .phi. being proportional to said electromagnetic torque,
• a first control member having an electrical input for receiving an electrical signal u.sub..phi. corresponding to a required angle of rotation .phi..sub.R of the second actuator body, and an electrical output for supplying an electrical signal u.sub.EM corresponding to the electromagnetic torque T.sub.EM which is required to achieve the required angle .phi..sub.R, and
• a second control member having an electrical input for receiving the signal u.sub.EM, and an electrical output for supplying a signal u.sub.I which is used to determine an electrical current supplied to said energizing means to exert the required electromagnetic torque T.sub.EM.