Supercharger rotor, shaft, and gear arrangement

In a rotary blower of the type including a housing assembly defining first and second transversely overlapping cylindrical chambers with end walls having through bores concentric to the central axis of each chamber for supporting antifriction bearings;

• a pair of meshed lobed rotors mounted within the chambers for parallel rotation about the axis of shafts fixed to the rotors and supported by the bearings;
• a drive gear fixed to one of the shafts and in mesh with a driven gear fixed to the other shaft and timed to prevent contact of the meshed lobes;
• the improvement comprising:
• a stepped bore extending through each rotor and defining a plurality of axially spaced bore portions concentric to the rotational axis of the rotor and of different diameters;
• and
• a plurality of annular axially spaced steps defined by each shaft, said steps concentric to the rotational axis of the shaft and of sufficiently different diameter with respect to each other and with respect to said bore portions to form pairs of inteference fits with at least two of said bore portions when said shaft is pressed into said stepped bore, and one of said plurality of shaft steps including a set of circumferentially spaced spline teeth extending parallel to said axis and formed of a material operative to broach mating splines in one of said plurality of bore portions when said shaft is pressed into said stepped bore, said spline teeth being disposed axially adjacent one of said shaft portions forming one of said interference fits and being operative to form the mating spline teeth after at least partial engagement of said one interference fit for preventing axial misalignment of the shaft in the bore while the spline teeth form said mating splines.

In a rotary blower of the type including first and second meshed, lobed rotors mounted for rotation within a housing and driven in timed relation with each other by first and second meshed timing gears secured to first and second shaft extensions respectively extending axially from the first and second rotors, the improvement comprising:

• a cylindrical bore surface extending through and concentric to the rotational axis of said first gear;
• a cylindrical shaft surface defined by said first shaft extension and of sufficiently different diameter with respect to the diameter of said bore to form an interference fit with said bore surface when said shaft extension is pressed in to said bore;
• and
• a set of circumferentially spaced spline teeth formed adjacent one of said surfaces and of a material operative to deform a portion of the other surface and thereby form mating splines in said other surface when said shaft extension is pressed into said bore, said spline teeth being operative to form the mating spline teeth after at least partial engagement of said interference fit for preventing axial misalignment of the shaft in the bore while the spline teeth form said mating splines.

In a rotary blower of the type including first and second meshed, lobed rotors mounted for rotation within a housing and driven in timed relation with each other by meshed timing gears secured to first and second shaft extensions respectively extending axially from the first and second rotors, the improvement comprising:

• a stepped bore extending through at least one of said gears, said stepped bore defined by a plurality of axially spaced bore portions concentric to the rotational axis of said one gear and of different diameters;
• and
• at least one of said shafts extensions including a plurality of axially spaced apart shaft portions concentric to the rotational axis of the shaft and of sufficiently different diameter with respect to each other and with respect to said bore portions of said gear to form axially spaced apart pairs of interference fits with at least two of said bore portions when said shaft portions are pressed into said stepped bore of the gear, one of said plurality of shaft portions including a set of circumferentially spaced spline teeth formed of a material operative to deform the surface of one of said plurality of bore portions and thereby form mating splines therein when said shaft extension is pressed into said stepped gear bore, said spline teeth being disposed axially adjacent one of said shaft portions forming one of said interference fits and being operative to form the mating spline teeth after at least partial engagement of said one interference fit for preventing axial misalignment of the shaft in the bore while the spline teeth form said mating splines.