Vacuum fill technique for hydrodynamic bearing

Abstract

A method is provided eliminating the need for capping the motor after filling, i.e. sealing an end of the motor after the fluid has been added. A septum or rubber plug is inserted in the bottom of the motor shaft in a counter bore which leads to a fluid reservoir for the bearing. The air-tight seal is also achieved by a temporary O-ring around the sides of the shoulder at the end of the shaft closing off the end of the bearing normally open to the surrounding environment. A needle is then inserted into the shaft via the septum, and the other end of the needle is placed in the oil that will be drawn into the motor. The motor, needle and container for the oil are placed in a vacuum chamber which is evacuated; the resulting pressure differential causes the air within the motor to exit through the needle and up through the oil. After all the air is withdrawn from the motor, the vacuum chamber's pressure is slowly returned to the ambient pressure causing oil to flow up through the needle into the vacuum which is now created within the bearing. While the vacuum is established, the oil is degassed and may also be heated. After filling, the motor can be removed from the vacuum chamber, the needle is withdrawn from the septum (which reseals), and the O-ring removed from the journal.

Dependencies are inferred from the claim text.