GB1077001A - Improvements in or relating to air filters - Google Patents

Abstract

1,077,001. Air filters. FRAM FILTERS Ltd. April 17, 1964 [April 17, 1963; Nov. 20, 1963], Nos. 15098/63 and 45890/63. Heading BIT. An air filter, one particularly suitable for use in conjunction with the air intake of an i.c. engine carburettor, comprises a two-part casing of plastics material and a removable air filter cartridge located between the two parts of the casing, the casing parts being removably secured together and the shape and disposition of the parts and of the cartridge being such that when assembled together air entering the filter through an inlet in the casing is constrained to pass through the filter cartridge and out of the filter through an outlet in the casing. The casing parts may for example be manufactured from polypropylene by injection moulding. In one embodiment (Fig. 1), the casing comprises a cup-shaped body portion 1 and a lid 2, the latter having a snap-action rim 3 adapted to engage a flange 4 of the wall 5 of the body portion 1. The filter cartridge 6, which is preferably of the form described in Patent No. 751,655, comprises an annulus of pleated paper embedded at each end in an impermeable elastomeric plastic end closure 7 having an integral inner peripheral gasket 8, which gaskets 8 slightly distorted so as to sealingly engage the body portion 1 and the lid 2 when these are secured together by the snap-action between the rim 3 and the flange 4. The base 9 of the body portion 1 is dish-shaped and provided with a re-entrant ridge 10 to aid in locating the filter cartridge 6 and merging with a central filter outlet tube 11. A cylindrical integrally moulded impact tube 12 extends outward from the wall 5. The lid 2 is also of dish-form and includes an integral recessed central region 13 which, again, assists in locating the filter cartridge 6. In an alternative embodiment (Fig. 4), the body portion 17 and lid 18 of the casing are removably secured together by means of bolts 19, a sealing ring 20 being provided to guard against air entry. The filter cartridge 21 has resilient top and bottom plastic end closures 22, 23 which are provided with peripheral gaskets 24 to ensure sealing engagement with the body portion 17 and lid 18. The base 25 of the body portion 17 has an annular curved recess 26 which is flattened at one diametrical end and provided with an air inlet port on either side of the flattened region, while at the opposite end 29 the outer peripheral edge of the recess is extended to meet the wall of the body portion 17. By this arrangement, two semicircular impact channels are formed, each leading from an air inlet port to the end 29 where air leaving the impact channels flows up into the interior of the casing outside the filter cartridge 21. The air then passes through the filter cartridge 21 before leaving the filter via an air outlet 31 in the base 25 of the body portion 17. If desired, small peripheral slots may be pierced in the walls of the impact channels just before the air passes up into the interior of the casing, thus permitting discharge of impurity particles by centrifugal action.