Chain saw filter assembly

Claim 1

A chain saw comprising: a metallic housing; a guide bar connected to said housing; a cutting chain carried by said guide bar; an internal combustion engine carried by said housing and including a carburetor; air passage means communicating with said carburetor; a stationary retainer plate attached to said housing and located in said air passage means; a vented metallic cover removably disposed over said air passage means; said cover and said retainer plate including fastener means for releasably attaching said cover to said houSing, said fastener means including a connector pin; a filter assembly for segregating particulate matter from inlet air passing through said inlet air passage means, said filter assembly comprising: at least one sheet of filter material, said filter sheet including an aperture accommodating passage of said connector pin, and a one-piece holder formed of a flexible material for supporting said flexible sheet of filter material, said holder comprising a pair of apertured plates integrally joined along a common side to define a hinge axis for said plates, each plate comprising: a peripheral rim, a network of criss-crossing ribs defining a plurality of apertures including an aperture receiving said connector pin, first resilient sealing ridge means projecting from both sides of said rim and extending substantially continuously around said rim, and second resilient sealing ridge means projecting from both sides of the portion of said rib network defining said pinreceiving aperture to surround the latter; said holder being foldable along said hinge axis to orient said plates in superposed relationship with said sheet of filter material sandwiched between said plates and engaged by internally located ones of said first and second sealing ridge means, with the apertures of said plates being in general alignment; and seating ledge means on said housing for receiving said filter assembly; said cover including pressure surface means engageable with externally located ones of said first and second sealing ridge means of one plate for urging internally located ones of said first and second sealing ridge means against opposite sides of said filter sheet, and urging externally located ones of said first and second sealing ridge means of the other plate against said seating ledge means, so as to impose an air seal around the periphery of said filter assembly and around said pin-receiving aperture when said cover is secured to said housing by said fastener means.