Oil filter for the cleaning of lubricating oil

Oil filter for the cleaning of lubricating oil, comprising:

• a filter housing having an open end and a closed end opposite the open end, a screw cap connectable to the open end of said housing, and a cylindrical supporting body having a first end rigidly attached to the closed end of said housing and a second free end facing in a direction toward and being axially spaced from the open end of said housing, whereby said filter housing is arranged at least approximately upright in the installed condition;
• a ring-shaped filter insert having an interior space and first and second opposed ends each respectively including an opening, wherein an inner peripheral surface of said opening at the first end of said filter insert is tightly seated radially on on a radially exterior surface of said cylindrical supporting body to form a sliding seat therewith, wherein the second free end of said cylindrical supporting body is positioned within the interior space of said filter insert;
• said filter housing including an oil inlet means for feeding contaminated oil to a feed-to space surrounding the filter insert, and an oil outlet means connected to said cylindrical supporting body for directing cleaned oil from a flow-off space formed by said interior space of the filter insert;
• a discharge duct in the closed end of the filter housing connected with an oil-collecting space for discharging oil remaining in the filter housing when the filter insert is changed, wherein said discharge duct is coaxially aligned with said cylindrical supporting body;
• a center bar coaxially aligned with respect to said cylindrical support body, said center bar having opposed first and second opposed ends, connecting means for connecting said cap to the first end of said center bar, wherein the first end of said center bar includes a piston flange having a radially exterior surface resting radially tightly against an inner peripheral surface of the opening in the second end of the filter insert to form a sliding seat therewith, said flange separating the inflow space from the flow-off space;
• a valve member attached to the second end of said center bar for automatically opening said discharge duct when said cap and center bar are removed from the housing with each change of the filter insert, wherein said valve member extends into and closes off said discharge duct when said cap and center bar are assembled to said housing;
• wherein said connecting means permits rotation of said cap in relation to the center bar.