Compressor load control for an auxiliary power unit
First Claim
1. In an aircraft auxiliary power unit, having an engine, a generator driven by the engine, an air compressor driven by the engine, the speeds of the engine, air compressor and generator being directly related,a fuel valve for the engine, and an engine control having means responsive to engine speed for controlling the fuel valve to maintain constant engine speed,an improved transient engine speed control, comprising:
- means for varying the loading of the air compressor on said engine; and
means responsive to the speed of one of the engine, generator or compressor for varying the compressor loading simultaneously with control of said fuel valve to minimize variation of the speed of the output frequency of the generator.
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Abstract
An auxiliary power unit for an aircraft drives an electrical generator and an air compressor. The auxiliary power unit is primarily intended for operation with the aircraft on the ground when other aircraft power systems are shut down. The auxiliary power unit may, however, be used in an emergency to supplement the main aircraft generating system, with the aircraft airborne. When the auxiliary power unit generator is used in conjunction with the aircraft generating system, inlet air to the compressor is controlled to vary the compressor load on the power unit to minimize power unit speed changes and electrical frequency transients.
81 Citations
3 Claims
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1. In an aircraft auxiliary power unit, having an engine, a generator driven by the engine, an air compressor driven by the engine, the speeds of the engine, air compressor and generator being directly related,
a fuel valve for the engine, and an engine control having means responsive to engine speed for controlling the fuel valve to maintain constant engine speed, an improved transient engine speed control, comprising: -
means for varying the loading of the air compressor on said engine; and means responsive to the speed of one of the engine, generator or compressor for varying the compressor loading simultaneously with control of said fuel valve to minimize variation of the speed of the output frequency of the generator. - View Dependent Claims (2, 3)
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Specification