Load anticipation control for a free turbine type of power plant

Claim 2

For an aircraft having an auxiliary power unit driven by the free turbine of a free turbine type of power plant driving an electrical alternator normally operating at a constant speed, and also driving a load compressor having inlet guide vanes for controlling the air flow to said load compressor, means for adjusting the area of said guide vanes and control means responsive to changes in electrical loads on said electrical alternator and the inlet pressure of said free turbine type of power plant for controlling said adjusting means.

Claim 3

For an aircraft a control system as claimed in claim 1, wherein said control means responsive to said changes in electrical load and the inlet pressure produces a linear signal as a compromise signal to the nonlinear relationship of the response time of said control for different altitudes.

Claim 4

For an aircraft having an auxiliary power unit a free turbine driven by a free turbine type of power plant, an electrical alternator driven by said free turbine normally operating at a constant speed, a load compressor also driven by said free turbine and having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjusting the area of said guide vanes to change the load on said load compressor, control means responsive to step changes in electrical loads on said electrical alternator for controlling said adjusting means, and means responsive to the inlet pressure of said power plant biasing said control means.

Claim 5

For an aircraft having an auxiliary power unit a free turbine driven by a free turbine type of power plant, an electrical alternator driven by said free turbine normally operating at a constant speed, a load compressor also driven by said free turbine and having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjusting the area of said guide vanes to change the load on said load compressor, control means responsive to step changes in electrical loads on said electrical alternator for controlling said adjusting means, and means responsive to the inlet pressure of said power plant biasing said control means.

Claim 6

For an aircraft having an auxiliary power unit driven by the free turbine of a free turbine type of power plant controlled by an independent control having an electrical alternator normally operating at a constant speed, a load compressor having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjusting the area of said guide vanes and control means including an electrical current sensor responsive to changes in electrical loads on said electrical alternator for controlling said adjusting means, and transducer means responsive to the inlet pressure of said power plant for electronically biasing said current sensor signal for controlling said adjusting means.

Claim 7

For an aircraft having an auxiliary power unit driven by the free turbine of a free turbine type of power plant controlled by an independent control having an electrical alternator normally operating at a constant speed, a load compressor having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjusting the area of said guide vanes and control means including an electrical current sensor responsive to changes in electrical loads on said electrical alternator for controlling said adjusting means, and transducer means responsive to the inlet pressure of said power plant for electronically biasing said current sensor signal for controlling said adjusting means.

Claim 8

For an aircraft as claimed in claim 4 including filtering means for filtering out the combined electrical load and inlet pressure signal.

Claim 9

For an aircraft as claimed in claim 5 including a limiter for preventing said combined electrical load and inlet pressure signal from going beyond a predetermined value.

Claim 10

An auxiliary power unit driven by the free turbine of a free turbine type of power plant, an electrical alternator driven by said free turbine so as to operate at a constant speed a load compressor also driven by the free turbine and having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjuSting the area of said guide vanes and means responsive to step changes in electrical loads on said electrical alternator for producing a first signal, means responsive to the inlet pressure of said power plant for producing a second signal and means for combining said first signal and said second signal for controlling said actuating means.

Claim 11

An auxiliary power unit driven by the free turbine of a free turbine type of power plant, an electrical alternator driven by said free turbine so as to operate at a constant speed a load compressor also driven by the free turbine and having inlet guide vanes for controlling the air flow to said load compressor, actuator means for adjuSting the area of said guide vanes and means responsive to step changes in electrical loads on said electrical alternator for producing a first signal, means responsive to the inlet pressure of said power plant for producing a second signal and means for combining said first signal and said second signal for controlling said actuating means.