Two-shaft engine for aircraft with high electric power demand

1. A two-shaft engine for aircraft with high electric power demand, comprising:

a high-pressure shaft connected to at least one generator and driven by a high-pressure turbine,

a low-pressure shaft driven by a low-pressure turbine,

an electronic engine control system,

an electromagnetic clutch connecting the low-pressure shaft to the high-pressure shaft for non-contact transmission of power from the low-pressure shaft to the high pressure shaft in a variable speed relationship, the electromagnetic clutch also connected to the engine control system, and

wherein the engine control system controls the electromagnetic clutch to create a freely settable frequency-controllable rotary field in the electromagnetic clutch to compensate for significant speed ratio differences from idle to flight power conditions between the low-pressure shaft and the high-pressure shaft that allows the low-pressure shaft to transmit power to the high-pressure shaft even though the low-pressure shaft operates at a lower RPM than the high-pressure shaft.

2. A two-shaft engine in accordance with claim 1 , wherein the electromagnetic clutch comprises:

a coil ring connected to the low-pressure shaft and including several annularly arranged coil sections activated by the engine control system to control the frequency of the rotary field, and

a magnet connected to the high-pressure shaft and engaging the rotary field of the coil ring.

3. A two-shaft engine in accordance with claim 2 , and further comprising a gear train for connecting each side of the electromagnetic clutch to the low-pressure shaft and to the high-pressure shaft, respectively.

4. A two-shaft engine in accordance with claim 3 , and further comprising:

a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

5. A two-shaft engine in accordance with claim 2 , and further comprising:

a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

6. A two-shaft engine in accordance with claim 1 , and further comprising:

a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

7. A two-shaft engine in accordance with claim 1 , and further comprising a gear train for connecting each side of the electromagnetic clutch to the low-pressure shaft and to the high-pressure shaft, respectively.

8. A method for controlling a two-shaft engine for aircraft with high electric power demand, comprising:

providing a high-pressure shaft connected to at least one generator and driven by a high-pressure turbine,

providing a low-pressure shaft driven by a low-pressure turbine,

providing an electronic engine control system,

providing an electromagnetic clutch connecting the low-pressure shaft to the high-pressure shaft for non-contact transmission of power from the low-pressure shaft to the high pressure shaft in a variable speed relationship,

connecting the electromagnetic clutch to the engine control system, and

controlling the electromagnetic clutch with the engine control system to create a freely settable frequency-controllable rotary field in the electromagnetic clutch to compensate for significant speed ratio differences from idle to flight power conditions between the low-pressure shaft and the high-pressure shaft that allows the low-pressure shaft to transmit power to the high-pressure shaft even though the low-pressure shaft operates at a lower RPM than the high-pressure shaft.

9. The method of claim 8 , and further comprising providing the electromagnetic clutch with:

a coil ring connected to the low-pressure shaft and including several annularly arranged coil sections activated by the engine control system to control the frequency of the rotary field, and

a magnet connected to the high-pressure shaft and engaging the rotary field of the coil ring.

10. The method of claim 9 , and further comprising providing a gear train for connecting each side of the electromagnetic clutch to the low-pressure shaft and to the high-pressure shaft, respectively.

11. The method of claim 10 , and further comprising:

providing a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

12. The method of claim 9 , and further comprising:

providing a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

13. The method of claim 8 , and further comprising:

providing a braking device positioned on the low-pressure shaft side of the electromagnetic clutch for arresting the clutch element connected to the low-pressure shaft in a non-rotatable position, in order to accelerate the high-pressure shaft at engine start with the rotary field.

14. The method of claim 8 , and further comprising providing a gear train for connecting each side of the electromagnetic clutch to the low-pressure shaft and to the high-pressure shaft, respectively.