Thrust controller for propulsion systems with commonly driven, controllable pitch propellers

Claim 2

A thrust controller for a propulsion system having a plurality of controllable pitch propellers driven by a common power source, said controller comprising the combination of input means for supplying thrust control signals having values representative of respective commanded thrust levels for said propellers, means responsive to said thrust control signals for controlling said power source to deliver an amount of power sufficient to satisfy the commanded thrust levels for said propellers while preventing the speed at which they are driven from dropping below a predetermined idle speed for said propulsion system means responsive to said thrust control signals for providing signals representative of respective commanded pitches for said propellers nonlinear transfer function means responsive to said thrust control signals for providing respective corrected pitch signals for each of said propellers whenever the thrust control signal for any of said other propellers is outside a predetermined pitch change range, said corrected pitch signals being representative of the pitches at which their respective propellers absorb from the power source substantially the power required to satisfy their commanded thrust levels, and means for selectively applying said commanded and corrected pitch signals to said propellers whereby the pitch of each propeller is determined by its commanded pitch signal when the thrust control signals for the other propellers are all within the pitch change range and by its corrected pitch signal when the thrust control signal for any of the other propellers is outside said pitch change range.

Claim 3

A thrust controller for a propulsion system having a plurality of controllable pitch propellers driven by a common power source, said propellers having nonlinear power versus speed characteristics, said controller comprising the combination of input means for supplying thrust control signals representative of respective commanded thrust levels for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded pitches for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded speeds for said propellers, means responsive to said commanded speed signals for selecting the signal representative of the highest of said commanded speeds, means for supplying a reference signal representative of a predetermined idle speed for said propulsion system means responsive to said selected commanded speed signal and said reference signal for controlling said power source to drive said propellers at a substantially constant speed selected to be the higher of said idle speed and said selected commanded speed, divider means responsive to said command speed signals and to said selected commanded speed signal for supplying signals representative of the ratios of the commanded speeds for the respective propellers to the highest of said commanded speeds nonlinear transfer function means actuated whenever the thrust control signal for any of said propellers is outside a predetermined pitch change range to provide for each of the other propellers a respective corrected pitch signal in response to the signal representative of ratios of their commanded speeds to the highest of said commanded speeds, said nonlinear transfer function being selected to compensate for the nonlinearity of the power versus speed characteristics of said propellers, whereby each of said corrected pitch signals represents the pitch at which its respective propeller absorbs substantially the same amount of power when driven at said constant speed as it would absorb if set at its commanded pitch and driven at its commanded speed, and means for selectively applying said commanded and said corrected pitch signals to said propellers whereby the pitch of each propeller is determined by its commanded pitch signal when thE thrust control signals for the other propellers are all within the pitch change range and by its corrected pitch signal when the thrust control signal for any of the other propellers is outside the pitch change range.

Claim 4

A thrust controller for a propulsion system having a plurality of controllable pitch propellers driven by a common power source, said propellers having nonlinear power versus speed characteristics, said controller comprising the combination of input means for supplying thrust control signals representative of respective commanded thrust levels for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded pitches for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded speeds for said propellers, means responsive to said commanded speed signals for selecting the signal representative of the highest of said commanded speeds, means for supplying a reference signal representative of a predetermined idle speed for said propulsion system means responsive to said selected commanded speed signal and said reference signal for controlling said power source to drive said propellers at a substantially constant speed selected to be the higher of said idle speed and said selected commanded speed, divider means responsive to said command speed signals and to said selected commanded speed signal for supplying signals representative of the ratios of the commanded speeds for the respective propellers to the highest of said commanded speeds nonlinear transfer function means actuated whenever the thrust control signal for any of said propellers is outside a predetermined pitch change range to provide for each of the other propellers a respective corrected pitch signal in response to the signal representative of ratios of their commanded speeds to the highest of said commanded speeds, said nonlinear transfer function being selected to compensate for the nonlinearity of the power versus speed characteristics of said propellers, whereby each of said corrected pitch signals represents the pitch at which its respective propeller absorbs substantially the same amount of power when driven at said constant speed as it would absorb if set at its commanded pitch and driven at its commanded speed, and means for selectively applying said commanded and said corrected pitch signals to said propellers whereby the pitch of each propeller is determined by its commanded pitch signal when thE thrust control signals for the other propellers are all within the pitch change range and by its corrected pitch signal when the thrust control signal for any of the other propellers is outside the pitch change range.

Claim 5

A thrust controller for a propulsion system having a plurality of controllable pitch propellers driven by a common power source, said propellers having nonlinear power versus speed characteristics, said controller comprising the combination of input means for supplying thrust control signals representative of respective commanded thrust levels for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded pitches for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded power levels for said propellers means responsive to said commanded power signals for providing a signal representative of an average power commanded per propeller from said power source means for amplifying the average power commanded per propeller signal to provide a signal representative of the total power commanded from said power source means responsive to said total power signal to control said power source to deliver the total power necessary to satisfy the commanded thrust levels for said propellers while preventing the speed at which said propellers are driven from dropping below a predetermined idle speed divider means responsive to said commanded power signals and said average power commanded per propeller signal to provide signals representative of the ratios of the commanded power levels for the respective propellers to the average power commanded per propeller nonlinear transfer function means to provide respective corrected pitch signals for said propellers in response to the signals representative of said ratios; said nonlinear means having a transfer function selected to compensate for the nonlinearity of the power versus speed characteristics of said propellers whereby the corrected pitch signal for any given propeller defines the pitch at which the propeller absorbs substantially the power commanded therefor whenever the thrust control signal for any of the other propellers is outside said pitch change range, and means for selectively applying the commanded and corrected pitch signals to said propellers whereby the pitch of each propeller is determined by its commanded pitch signal when the thrust control signals for the other propellers are all within said pitch change range and by its corrected pitch signal when the thrust control signal for any of said other propellers is outside the pitch change range.

Claim 6

A thrust controller for a propulsion system having a plurality of controllable pitch propellers driven by a common power source, said propellers having nonlinear power versus speed characteristics, said controller comprising the combination of input means for supplying thrust control signals representative of respective commanded thrust levels for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded pitches for said propellers, means responsive to said thrust control signals for providing signals representative of respective commanded power levels for said propellers means responsive to said commanded power signals for providing a signal representative of an average power commanded per propeller from said power source means for amplifying the average power commanded per propeller signal to provide a signal representative of the total power commanded from said power source means responsive to said total power signal to control said power source to deliver the total power necessary to satisfy the commanded thrust levels for said propellers while preventing the speed at which said propellers are driven from dropping below a predetermined idle speed divider means responsive to said commanded power signals and said average power commanded per propeller signal to provide signals representative of the ratios of the commanded power levels for the respective propellers to the average power commanded per propeller nonlinear transfer function means to provide respective corrected pitch signals for said propellers in response to the signals representative of said ratios; said nonlinear means having a transfer function selected to compensate for the nonlinearity of the power versus speed characteristics of said propellers whereby the corrected pitch signal for any given propeller defines the pitch at which the propeller absorbs substantially the power commanded therefor whenever the thrust control signal for any of the other propellers is outside said pitch change range, and means for selectively applying the commanded and corrected pitch signals to said propellers whereby the pitch of each propeller is determined by its commanded pitch signal when the thrust control signals for the other propellers are all within said pitch change range and by its corrected pitch signal when the thrust control signal for any of said other propellers is outside the pitch change range.