Abstract: A method of aligning the rotors of a Roots-type blower includes the steps of immobilizing an idler gear with reference to a housing of a Roots-type blower. A drive rotor is fixedly disposed on a drive shaft inside the housing with an idler rotor engaged with the drive rotor and fixedly disposed on an idler shaft. A drive gear is rotatably disposed on the drive shaft and the idler gear is engaged with the drive gear and fixedly disposed on the idler shaft. The drive shaft is rotated in opposite directions to first and second extents of travel. Each extent of travel is defined by contact of the drive rotor against the idler rotor. The drive shaft is positioned at a determined rotational angle between the first and second extents of travel and the drive gear is then fixed to the drive shaft.

Abstract: A method of aligning the rotors of a Roots-type blower includes the steps of immobilizing an idler gear with reference to a housing of a Roots-type blower. A drive rotor is fixedly disposed on a drive shaft inside the housing with an idler rotor engaged with the drive rotor and fixedly disposed on an idler shaft. A drive gear is rotatably disposed on the drive shaft and the idler gear is engaged with the drive gear and fixedly disposed on the idler shaft. The drive shaft is rotated in opposite directions to first and second extents of travel. Each extent of travel is defined by contact of the drive rotor against the idler rotor. The drive shaft is positioned at a determined rotational angle between the first and second extents of travel and the drive gear is then fixed to the drive shaft.

Abstract: Roots-type blowers with helical cycloidal rotors exhibit variation in leakback flow with angular position intrinsic to these rotor geometries. Calibration of individual blowers using a combination of high-resolution alignment and enhanced detection of residual noise phenomena permits noise in as-produced blowers to be significantly attenuated. Intrinsic lower limits of noise induced by leakback variation are associated with manufacturing tolerances, necessary clearances, and particular geometric considerations. Gross alignment errors (excluding contact between rotors) produce a characteristic noise pulse rate that is three times the shaft rate. Proper alignment suppresses this and reveals a pulse sequence at double this rate and at about half of the amplitude of faulty alignment. The novel process explains the error mechanisms and defines repeatable calibration methods for a mass-production environment, introducing appropriate gauges and methods for the task.

Abstract: Roots-type blowers with helical cycloidal rotors exhibit variation in leakback flow with angular position intrinsic to these rotor geometries. Calibration of individual blowers using a combination of high-resolution alignment and enhanced detection of residual noise phenomena permits noise in as-produced blowers to be significantly attenuated. Intrinsic lower limits of noise induced by leakback variation are associated with manufacturing tolerances, necessary clearances, and particular geometric considerations. Gross alignment errors (excluding contact between rotors) produce a characteristic noise pulse rate that is three times the shaft rate. Proper alignment suppresses this and reveals a pulse sequence at double this rate and at about half of the amplitude of faulty alignment. The novel process explains the error mechanisms and defines repeatable calibration methods for a mass-production environment, introducing appropriate gauges and methods for the task.