Auxiliary power drive mechanism for a gas turbine engine

Claim 1

IN AN ACCESSORY DRIVE FOR A GAS TURBINE ENGINE OF THE TYPE EMPLOYING A POWER TURBINE AND A GAS PRODUCER TURBINE MOUNTED FOR ROTATION INDEPENDENTLY OF EACH OTHER WITH A POWER TURBINE SHAFT DRIVEN BY SAID POWER TURBINE AND A SEPARATE GAS PRODUCER TURBINE SHAFT DRIVEN BY SAID GAS PRODUCER TURBINE, GAS DIRECTING MEANS FOR IMPELLING SAID TURBINES AND AFFORDING A RANGE OF ROTATIVE SPEEDS AT VARYING POWER OUTPUTS DOWNWARD FROM A DESIGN MAXIMUM ROTATIVE SPEED FOR EACH OF SAID TURBINES, THE COMBINATION THEREWITH OF AN ACCESSORY DRIVE MEANS COMPRISING: AN ACCESSORY DRIVE SHAFT; A FIRST ROTATABLE CONNECTION FROM SAID POWER TURBINE SHAFT TO SAID ACCESSORY DRIVE SHAFT, INCLUDING A FIRST ROTATIVE SPEED REDUCING GEAR TRAIN AND A FIRST ONE-WAY DRIVE CONNECTION; A SECOND ROTATABLE DRIVE CONNECTION FROM SAID GAS PRODUCER TURBINE SHAFT ALSO TO SAID ACCESSORY DRIVE SHAFT AND INCLUDING A SECOND ROTATIVE SPEED REDUCING GEAR TRAIN, AND A SECOND ONE-WAY DRIVE CONNECTION BETWEEN SAID SECOND GEAR TRAIN AND SAID ACCESSORY DRIVE SHAFT; EACH OF SAID FIRST AND SECOND ONE-WAY DRIVE CONNECTIONS BEING POSITIONED BETWEEN ITS RESPECTIVE GEAR TRAIN AND SAID ACCESSORY DRIVE SHAFT, WHEREBY THE GREATER SPEED OF ROTATION IMPOSED ON SAID ACCESSORY SHAFT BY EITHER SAID FIRST OR SECOND ONE-WAY DRIVE CONNECTION WILL IMPART ROTATION TO SAID ACCESSORY SHAFT; SAID FIRST GEAR TRAIN AND SECOND GEAR TRAIN HAVING DESIGNED RELATIVE SPEED REDUCING RATIOS PRODUCING SUBSTANTIALLY GREATER SPEED OF ROTATION AT SAID FIRST ONE-DAY DRIVE CONNECTION OVER SAID SECOND ONE-WAY DRIVE CONNECTION WHEN SAID POWER TURBINE AND SAID GAS PRODUCER TURBINE ARE ROTATING AT THEIR SAID RESPECTIVE MAXIMUM DESIGNED SPEEDS OF ROTATION; THEREBY TO ASSURE DRIVE OF SAID ACCESSORY SHAFT BY SAID POWER TURBINE WHEN SAID POWER TURBINE SPEED EXCEEDS THE SPEED OF SAID GAS PRODUCER BY A PREDETERMINED AMOUNT AND ONLY SHIFTING DRIVE TO SAID GAS PRODUCER TURBINE WHEN SPEED OF ROTATION OF SAID POWER TURBINE IS REDUCED BELOW SAID PREDETERMINED AMOUNT RELATIVE TO THE SPEED OF ROTATION OF SAID GAS PRODUCER TURBINE AND SHIFTING SAID DRIVE TO SAID GAS PRODUCER TURBINE IN THE LOWER PORTION OF THE SPEED RANGE OF SAID POWER TURBINE WHEN SPEED OF ROTATION OF SAID POWER TURBINE IS NOT SUBSTANTIALLY HIGHER THAN THAT OF SAID GAS PRODUCER TURBINE.