Filter apparatus with an accordion-type filter medium for compaction and removal of sludgy filter cake

Claim 1

A filter apparatus for removal of relatively fine solid particles from a fluid, comprising in combination: a. a filter drum having a fluid inlet opening therethrough for the introduction of the fluid to be filtered, said filter drum having an open end and a closed end; b. an accordion filter medium mounted within said filter drum, said accordion filter medium including: 1. first and second end plates slidably but fluid-tightly fitted in said filter drum for longitudinal movement therethrough, said first end plate being normally held at said open end of said filter drum and having a filtrate outlet opening therethrough; 2. a filter screen; and 3. means for supporting said filter screen in the form of a bellows between said first and second end plates; whereby said filter screen is contractable and expansible as desired with the movement of said first and second end plates toward and away from each other; c. a cylinder actuator connected to said closed end of said filter drum in coaxial relationship, said cylinder actuator including: 1. at least one piston; and 2. at least one piston rod connected at one end to said piston and at the other end to said first end plate of said accordion filter medium by slidably extending through said closed end of said filter drum and said second end plate; whereby said cylinder actuator is capable of causing said first and second end plates to move toward each other for compaction of filter cake on said filter screen and of causing said accordion filter medium to move out of said open end of said filter drum for removal of the compacted filter cake, said filter screen being expanded upon movement of said accordion filter medium out of said open end; and d. means for removing the compacted filter cake from said filter screen upon movement of said accordion filter medium out of said open end of said filter drum.