1. Field of the Invention
The invention relates to an air filter for internal combustion engines having a primary air region and a secondary air region disposed within a housing. The primary air comes from air located outside the internal combustion engine while the secondary air comes from crankcase emissions flowing from a crankcase in the internal combustion engine to the air filter.
2. Description of the Prior Art
Various filters for reducing crankcase emissions are known an the art. For example, U.S. Pat. No. 5,125,940 to Stanhope, et al. discloses a venturi element 40 disposed outside of the downstream end of the housing 16 of the in-line air filter apparatus 10. Ambient air travels through tubular air filter 34, outside-in, and to the air intake hose 12 via the concave venturi element.
U.S. Pat. No. 5,562,746 to Raether discloses an air filter assembly 10 having a plurality of filters 32 mounted to side walls 17 via tube sheet structure 28. A concave venturi 70 is fixedly coupled to each filter 32 by means of the tube sheet structure 28 and the venturi flanges 88.
U.S. Pat. No. 4,272,263 to Hancock discloses a gas cleaning arrangement having a venturi sheet 4 disposed within a bag housing 1. Venturi sheet 4 supports a plurality of tubular filter arrangements 7 where each filter 7 includes a convex venturi 24, and accordingly the venturi is contained within housing 1.
U.S. Pat. No. 5,383,356 to Zurek et al. discloses a concave venturi 76 that is separately connected to the outside of the downstream end of housing 86 or may be integrated with the housing as a single unitary element.
U.S. Pat. Nos. 4,713,097 to Grawi et al 5,106,397 to Jaroszcyk, et al. and 5,120,334 to Cooper each disclose an air filter having a venturi, integrated with a housing, where the venturi is not adjacent to an air filter element.
U.S. Pat. Nos. 4,272,262 to Britt et al. 4,834,784 to Biganset, and 5,196,653 to Kiss disclose air filters with venturi elements.
The present invention is an improvement over the prior art, because none of the prior art shows an air filter device having a venturi element shaped to be contained completely within the body of the housing and positioned such that crankcase emissions flow from a secondary air region past the primary air region and out of the housing. In addition, the prior art does not disclose the venturi element described above that is fixedly attached to the downstream end of an air filter element.