What are the main components of an oil filter?

Oil Filter and Oil Filtration System Description

Oil filters can be categorized into grease filters and thin oil filters based on the type of oil they process. Their core function is to block contaminants from entering the lubrication system, thereby extending the system's service life.

Within lubrication systems, engine oil must undergo rigorous filtration before being delivered to friction surfaces. This ensures unobstructed oil flow while preventing impurities from scratching or scoring component surfaces. To balance optimal filtration efficiency with low flow resistance, systems typically employ a configuration where a coarse filter is connected in series with the main oil passage, while a fine filter is connected in parallel.

1. Float-Type Oil Collector Filter

The core function of the collector filter is to remove large particulate contaminants from the lubricating oil before it enters the oil pump, ensuring the pump operates normally. Connected to the oil pump inlet, its operational sequence is as follows:

When the oil pump starts, oil is first drawn in through the narrow gap between the cover and the float;

After coarse contaminants are filtered out by the mesh screen, the oil enters the pump through a pipe welded to the float;

If the mesh screen becomes clogged, increased suction in the inlet pipe overcomes the screen's resistance, causing the ring opening (original text “bad opening” is a typo) to separate from the cover. Oil then flows directly into the suction pipe through the ring opening, preventing oil starvation in the pump.

2. Coarse Filter (Full-Flow Filter)

The coarse filter is connected in series between the oil pump and the main oil gallery. As it filters all engine oil, it is also known as a full-flow filter, primarily designed to remove larger contaminants from the oil. Paper-based coarse filters are currently the most widely used globally. Their structure mainly includes a top cover, outer housing, paper filter element, and a bypass valve.

During operation, pressurized lubricating oil first enters the cavity surrounding the filter element. Larger contaminants in the oil are intercepted by the paper element. The filtered, clean lubricating oil then enters the inner cavity of the filter element and is ultimately delivered through the outlet port to the main oil gallery of the cylinder block.