Fundamental Investigation of Charge Injection Type of Electrostatic Oil Filter

Abstract

This paper proposes a new type of electrostatic oil filter and presents results of filtration experiments. Aiming at increasing the amount of electric charges on contaminants in oils and thus increasing the filtration speed of an electrostatic oil filter, electric charges are forcibly injected into oils by applying a high DC voltage to an electrode pair consisting of an electrode with many sharp projections on its both sides, called the emitter electrode, and of two smooth electrodes. Fourteen types of lubricating oils, into which a test powder is mixed at a fixed concentration, are used for filtration experiments. The experiments show that the filtration speed is increased to a great or some degree for most of the oils and that for the majority of the oils, the electrification polarity of a few tens to one hundred percent of powders can be inverted by injecting electric charges with the opposite polarity to the original electrification polarity of the powders. It is also shown that no definite correlation can be seen between the physical properties (conductivity and viscosity) of oils and the degree of the increase in the filtration speed due to charge injection.

Keywords

• electrostatic filter
• charge injection
• lubricating oil
• coulomb force
• reuse