Automatic continuously backflow washing-type filter

Claim 1

An automatic continuous backflow washing type filter for use on the suction side of a pump comprising a vertically cylindrical housing the side wall of which is provided with four intergral radially and inwardly extending annular flanges positioned at different heights on said side wall and a bottom wall, a filtrate outlet chamber defined within said housing above the uppermost of said flanges, a filtering chamber defined between said uppermost flange and the flange right below the uppermost flange, a material oil inlet chamber defined between said second higher flange and the flange right below the second higher flange, a backflow washing filtrate inlet chamber defined between said third higher flange and the lowermost flange, a condensation chamber defined between said lowermost flange and bottom wall, a sludge discharge port provided adjacent said bottom wall in communication with said condensation chamber, a primary filtering screen receiving member being receivable in said housing between said two upper flanges and having upper and lower annular flanges securable to the two housing flanges and a plurality of radially and inwardly extending ribs, a secondary filtering screen receiving member received within said housing and extending downwardly from said third-mentioned housing flange toward said housing bottom wall beyond said lowermost housing flange, said secondary filtering screen receiving member being provided with upper and lower annular flanges which are secured to said thirdmentioned housing flange and fitted in said lowermost housIng flange, respectively and a plurality of ribs radially and inwardly extending, a filtering screen support member extending vertically within said first and second filtering screen receiving members and having an uppermost radially and outwardly extending annular flange secured to said upper flange on the primary filtering screen receiving member, a second radially and outwardly extending higher annular flange positioned between the two upper flanges of the primary filtering screen receiving member and spaced from the side wall of the associated screen receiving member and third and fourth radially and outwardly extending annular flanges positioned below said lower flange of the secondary filtering screen receiving member and spaced from the side wall of the associated screen receiving member, said filtering screen support member being further provided with a plurality of radially and outwardly extending ribs between said first and second flanges on the screen support member, backflow washing filtrate inlet ports positioned between said upper and lower flanges on the secondary filtering screen receiving member, guide openings positioned just above said upper flange on the secondary filtering screen receiving chamber, slit groups positioned at different heights in the screen support member and guide openings in communication with a backflow washing filtrate outlet chamber provided in said housing, a primary filtering screen secured to said two upper flanges on the filtering screen support member, a secondary filtering screen secured to said two lower flanges on the filtering screen support member, and a rotary backflow washing cock extending vertically within said filtering screen support member and having a plurality of integral cock sections defined by a plurality of discs and provided with a plurality of communications openings therein, the uppermost disc of said plurality of discs having a filtrate outlet, said uppermost and next higher discs being loosely fitted in the screen receiving member in the positions corresponding to said two upper flanges on the screen support member and defining a relatively large opening port on one side and a backflow washing filtrate outlet port on the opposite side which is in communication with one of said communication openings, the second and third higher discs defining an opening port having the same opening angle as said first-mentioned opening port on one side and a backflow washing filtrate inlet port on the other side which is in communication with another one of said communication openings, the third and fourth higher discs defining a backflow washing filtrate guide opening which is in communication with the last one of said communication openings and a backflow washing filtrate outlet port extending below the lowermost disc.