Drive shaft for compressor

1 . A compressor assembly comprising:

a motor including a stator and a rotor;

a drive shaft comprising an integral elongate member defining an elongate central portion and first and second end portions located on opposite ends of said central portion, said drive shaft defining a rotational axis, said first end portion defining a first cross-sectional configuration oriented perpendicular to said rotational axis, said second end portion defining a second cross-sectional configuration oriented perpendicular to said rotational axis and said central portion defining a third cross-sectional configuration oriented perpendicular to said rotational axis wherein each of said first and second cross-sectional configurations has an outer perimeter disposed radially within the outer perimeter of said third cross-sectional configuration relative to said rotational axis, said drive shaft extending through said rotor with said central portion being rotationally secured to said rotor, said first end portion disposed proximate a first end of said motor and said second portion disposed proximate a second end of said motor;

a first compressor mechanism disposed proximate said first end of said motor and operatively coupled to said first end portion of said drive shaft wherein said first end portion rotationally drives said first compressor mechanism; and

a second compressor mechanism disposed proximate said second end of said motor and operatively coupled to said second end portion of said drive shaft wherein said second end portion rotationally drives said second compressor mechanism.

2 . The compressor assembly of claim 1 wherein said first and second compressor mechanisms are rotary compressor mechanisms.

3 . The compressor assembly of claim 2 wherein said first and second compressor mechanisms respectively include first and second rollers respectively mounted on said first and second end portions of said drive shaft wherein said first and second rollers each have an outer cylindrical surface respectively defining first and second roller axes wherein said first and second roller axes are oriented parallel to said rotational axis, each of said first and second roller axes being spaced from said rotational axis by a common distance and wherein said first roller axis is positioned diametrically opposite said second roller axis relative to said rotational axis.

4 . The compressor assembly of claim 1 wherein said first and second end portions each define a substantially similar non-circular cross-sectional configuration, said first and second configurations being rotationally offset by 180 degrees relative to said rotational axis.

5 . The compressor assembly of claim 2 wherein said first and second compressor mechanisms respectively include first and second rollers respectively mounted on said first and second end portions of said drive shaft wherein said first and second rollers each have an outer cylindrical surface respectively defining first and second roller axes wherein said first and second roller axes are oriented parallel to said rotational axis, each of said first and second roller axes being spaced from said rotational axis by a common distance.

6 . The compressor assembly of claim 5 wherein said central portion is substantially cylindrical and said first and second end portions each define a substantially similar non-circular cross-sectional configuration, said first and second configurations being rotationally offset by 180 degrees relative to said rotational axis.

7 . The compressor assembly of claim 6 wherein said central portion of said drive shaft is secured with said rotor in a shrink fit engagement.

8 . A compressor assembly comprising:

a motor including a stator and a rotor;

a drive shaft comprising an integral elongate member defining an elongate central portion and first and second end portions located on opposite ends of said central portion, said drive shaft defining a rotational axis, said first end portion defining a first cross-sectional configuration oriented perpendicular to said rotational axis, said second end portion defining a second cross-sectional configuration oriented perpendicular to said rotational axis and said central portion defining a third cross-sectional configuration oriented perpendicular to said rotational axis wherein each of said first and second cross-sectional configurations has an outer perimeter disposed radially within the outer perimeter of said third cross-sectional configuration relative to said rotational axis and said first and second end portions each define a substantially similar non-circular cross-sectional configuration, said first and second configurations being rotationally offset by 180 degrees relative to said rotational axis, said drive shaft extending through said rotor with said central portion being rotationally secured to said rotor, said first end portion disposed proximate a first end of said motor and said second end portion disposed proximate a second end of said motor;

a first rotary compressor mechanism disposed proximate said first end of said motor and operatively coupled to said first end portion of said drive shaft wherein said first end portion rotationally drives said first compressor mechanism; and

a second rotary compressor mechanism disposed proximate said second end of said motor and operatively coupled to said second end portion of said drive shaft wherein said second end portion rotationally drives said second compressor mechanism.

9 . The compressor assembly of claim 8 wherein said first and second compressor mechanisms respectively include first and second rollers respectively mounted on said first and second end portions of said drive shaft wherein said first and second rollers each have an outer cylindrical surface respectively defining first and second roller axes wherein said first and second roller axes are oriented parallel to said rotational axis, each of said first and second roller axes being spaced from said rotational axis by a common distance and wherein said first roller axis is positioned diametrically opposite said second roller axis relative to said rotational axis.

10 . The compressor assembly of claim 8 wherein said drive shaft is substantially rotationally balanced.

11 . The compressor assembly of claim 10 wherein said central portion is substantially cylindrical and said first and second end portions each define a substantially similar non-circular cross-sectional configuration, said first and second configurations being rotationally offset by 180 degrees relative to said rotational axis.

12 . The compressor assembly of claim 11 wherein said central portion of said drive shaft is secured with said rotor in a shrink fit engagement.

13 . A method of assembly a compressor assembly, said method comprising:

providing a motor having a stator and a rotor, the rotor having an axially extending central bore;

forming a drive shaft with an integral elongate member wherein the drive shaft includes an elongate central portion and first and second end portions located on opposite ends of the central portion, said drive shaft defining a rotational axis, said first end portion defining a first cross-sectional configuration oriented perpendicular to said rotational axis, said second end portion defining a second cross-sectional configuration oriented perpendicular to said rotational axis and said central portion defining a third cross-sectional configuration oriented perpendicular to said rotational axis wherein each of said first and second cross-sectional configurations has an outer perimeter disposed radially within the outer perimeter of said third cross-sectional configuration relative to said rotational axis;

securing the drive shaft to the rotor by thermally expanding the rotor, inserting one of the first and second end portions of the drive shaft through the central bore of the rotor wherein the first end portion of the drive shaft accessible from a first end of the rotor and the second end portion of the drive shaft is accessible from a second end of the rotor, and allowing the rotor to cool and rotationally secure the drive shaft in the central bore of the rotor in a shrink-fit engagement;

operably coupling a first compressor mechanism to the first end portion of the drive shaft wherein the drive shaft rotationally drives the first compressor mechanism; and

operably coupling a second compressor mechanism to the second end portion of the drive shaft wherein the drive shaft rotationally drives the second compressor mechanism.

14 . The method of claim 13 wherein the first and second compressor mechanisms are rotary compressor mechanisms and wherein operably coupling the first and second compressor mechanisms to the first and second end portions of the drive shaft includes respectively mounting first and second rollers on the first and second end portions wherein each of the first and second rollers has an outer cylindrical surface respectively defining first and second roller axes, each of the first and second roller axes being spaced from the rotational axis by a common distance and wherein the first roller axis is positioned diametrically opposite the second roller axis relative to the rotational axis.

15 . The method of claim 13 wherein the first and second end portions each define a substantially similar non-circular cross-sectional configuration, the first and second configurations being rotationally offset by 180 degrees relative to said rotational axis.

16 . The method of claim 13 wherein the drive shaft is substantially rotationally balanced.

17 . The method of claim 16 wherein the central portion is substantially cylindrical and the first and second end portions each define a substantially similar non-circular cross-sectional configuration, the first and second configurations being rotationally offset by 180 degrees relative to the rotational axis.