Patent GB-950810-A (GB)
Title: Improvements in or relating to liquid filters
IPC: B01D27/06
Filed: 1962-08-24
Abstract: 950,810. Filters. FRAM CORPORATION. Aug. 24, 1962 [Oct. 31, 1961], No. 32608/62. Heading B1D. [Also in Division F2] A liquid filter comprises a filter housing 10 having an inlet 17 and at one end of the housing an end wall 13 provided with a central outlet 16, a filter cartridge 20 of the outside-in flow type, suitably of pleated paper disposed in said housing and having a central bore 23 communicating with the outlet so that liquid from the inlet or high-pressure side of the cartridge is adapted to flow through the cartridge to the outlet or low-pressure side of the cartridge, means forming a by-pass channel leading from the high-pressure to the low-pressure side of the cartridge comprising a ring-shaped passage between an inner wall 24 and an outer wall 25 and a spring-actuated by-pass valve for closing the said passage comprising an annular gasket 33 having an annular bead 36 adapted to enter and sealingly engage the outlet end of the passage. As shown, the annular bead 36 is formed with a flat face 37 adapted to be exposed to the pressure of the unfiltered liquid and diverging side walls 38, 39 adapted to enter and sealingly engage the outer end of the ring- shaped passage. In Figs. 2, 3 and 4 the ring- shaped passage spaces the cartridge from the end wall 13. In Fig. 1, the central bore 23 of the filter cartridge is connected with the outlet 16 and the ring-shaped passage is located between the exterior of the cartridge 20 and the outlet 16. The gasket 33 is preferably made of synthetic rubber withstanding hot oil, and the ring-shaped passage may be made of sheet metal, cast aluminium or moulded plastic. In operation, Figs. 2, 3 and 4, the by-pass valve gasket 33 is normally closed, as in Fig. 3, under the pressure of spring 32, the V-shape of the side walls 38, 39 giving a self-centering and wedging action ensuring a tight seal. Oil enters the inlet 17, passes the anti-drain valve formed by gasket 18 and spring disc 19 and circulates in the direction of the arrows, Fig. 2, passing through filter 20 down the centre tube 23 through the central hole in the wall 31 of the cage 30 housing spring 32, and out of the outlet 16. The hold-down blade spring member 41 exerts pressure on the filter to hold the member 24, 25 of the by-pass firmly seated on gasket 28. When the oil pressure becomes abnormally high owing to the filter being dirty or the oil being cold, the pressure of oil passing through holes 26 in the member 24, 25 against the flat face 37 of the bead lifts the valve 33 to the open position of Fig. 4, so that the oil can by-pass the filter and pass in the direction of the arrows in Fig. 4 through the central hole in member 24, 25 and out of outlet 16, the oil flow exerting a lifting action upon the flat shoulder 40 of the gasket 33, which also directs the oil flow downwardly into outlet 16. In Fig. 1 the by-pass valve is mounted at the opposite end of the filter housing, and a coiled spring 43 is fitted to press down on the filter cartridge and hold it sealed on the spacing ring 44 at the opposite end of the cartridge, which ring rests on the anti-drain valve 18, 19 or on a gasket 28, and has an annular flange 45 on which the filter rests. In this modification, the by-pass valve is mounted in the reversed position as shown and the end wall 27 is imperforate, to prevent oil flowing downwardly into cage 30 and centre tube 23 when the valve 33 opens.