Patent GB-678939-A (GB)
Title: Improved liquid filter
IPC: B01D29/21
Filed: 1949-11-02
Abstract: 678,939. Filters; filtering media. GENERAL MOTORS CORPORATION. Nov. 2, 1949 [Nov. 4, 1948], No. 28050/49. Class 46 A combined filter unit comprises a bellows coarse filter element and a bellows fine filter element, the elements having a plurality of rows of transverse pleats and a central opening, and one or more tubes or like struts coaxial with and positioned in the openings of the elements and secured by plates to the ends of the elements. An element may be made by scoring and folding a sheet 10, Fig. 2, of paper impregnated with phenol formaldehyde resin and joining the edges 30, 31 to form a bellows having a regular octagonal cross-section. It is then cured to form a rigid structure. In a combination full-flow and partial-flow filter 131, Fig. 6, the fullflow element 101 is formed of coarse paper and the partial-flow element .102 of fine paper. Both elements are mounted on a tube 103 to form the combined unit 104. The bottom end of the element 101 is closed by a clamping plate 106 which is rectangular with rounded ends. The rounded ends are inserted under the edges of the two opposite end pleats which form "pockets" " whereupon the straight edges of the plate lie substantially along the centres of the intermediate pleats. The outer portions of these latter pleats are then folded over the straight edges of the clamping plate 106 (see Fig. 7 (Cancelled)). The plate 106 is held against the bottom of a detent 108 by a bottom plate 107 having a central flange welded to the tube 103. The top of the element 101 is folded about a similar clamping plate 114 held against the top,of a detent 112 on the tube 103 by a strut tube 120 through a clamping plate 116 at the lower end of the element 102 and a centre plate 115. The upper clamping plate 117 for the element 102 is held against the top of the strut tube 120 by an upper end plate 118 welded to the tube 103. Oil to be filtered enters at 151, 152, Fig. 8, and a large proportion flows through the element 101, apertures 111 in tube 103 and bore 147 to outlet 149, Fig. 8, whence it passes to an engine lubricating system. The remainder of the oil flows through the element 102, apertures 124 in the strut tube 120. apertures 126 (located above a seal 121) in tube 103, and an aperture 144 to the inside of a hollow post 133 whence it passes through an outlet 148 to the engine crankcase. A byepass valve 158 between the inlet space 151. Fig. 8, and the " coarsefiltered " outlet 149 is provided. A spring 141 holds the unit 104 against an annular wall 132a of the base 132. In an alternative construction (not shown in full), the strut tube 120 is dispensed with and the tube 103 is replaced bv two separate tubes 203, 204, Fig. 10, each perforated throughout its length. Annular sealing gaskets of which one, 226, is shown, are inserted in the ends of the tube 204 and a small orifice provided in the post 243 between them. Beaded clamping plates are provided of which two, 221 and 212, are shown, and the lower end plate 223 of the upper portion of the unit is secured to the upper end plate 214 of the lower portion of the unit by rolling their edges together. In Fig. 13, the coarse filter element 301 is of twelve-sided prismatic form and is arranged outside the fine filter element 302 which is octagonal as before. The lower end of the fine element 302 is secured between a clamping plate 306 and and an end plate 307 which are secured to tube 303 which has only two perforations. The upper end is secured between a clamping plate 312 and an end plate 313, the latter having a clearance about the tube 303 and serving also as clamping plate for the upper end of the element 301. The lower end of the element 301 is secured between a flanged end plate 336 and a doubly-flanged clamping plate 331 welded to the tube 303 at 335. A flange 337 of the end plate 336 is secured to a flange 332 on the clamping plate 331. Liquid from an inlet 367 surrounds the element 301 and some of the liquid passing through it leaves by apertures 334 in the clamping plate 331 and the coarse-filtered outlet passage 362. The remainder passes through the element 302. orifice 357 and outlet 356. A passage 363 for a pressure gauge and a byepass passage (not shown), are provided. Alternative media for the elements are: laminated paper, cloth, and wire mesh. The Specification as open to inspection under Sect. 91, comprises also a filter 57, Fig. 6 (Cancelled), incorporating a single element 45 having its ends secured between clamping plates 48, Fig. 7 (Cancelled), and end plates 47. A byepass valve 73 is normally urged to closed position by a spring 74 whose other end rests against an apertured seat 75 abutting against a shouldered retaining pin 76. This subject-matter does not appear in the Specification as accepted.