Piston type cleaning valve

Claim 1

A self-cleaning valve comprising: a body having a cylindrical flow channel therein and provided with a fluid inlet at one end of said channel and an outlet in a side wall of said channel; a closing device associated with said body comprising an actuating member and a piston unit connected to said actuating member, said piston unit being displaceable in said flow channel into a closing position between said inlet and said outlet for closing said valve and into an opening position for allowing communication between said inlet and said outlet for opening the valve, said piston unit including a sealing ring of resilient material and at least two piston rings; said actuating member comprising: a first actuating means including a push pipe associated therewith, a second actuator means including a pull rod extending through said push pipe for moving said pull rod within said pull pipe and for locking said push rod in said pull pipe closing said valve; said piston unit further including a first flange connected to said push pipe, a second flange connected to said pull rod, and said flanges being spaced apart from each other axially and defining a piston and having a gap therebetween; and, said sealing ring of resilient material and said at least two piston rings being fitted within said gap, said piston rings and said resilient material together with said piston defining said piston unit, the diameter of said sealing ring being smaller than the diameter of said piston rings in an unlocked position of said second actuator means whereby said piston rings shear off impurities adhered to the wall of said flow channel during movement of said piston rings in contact with said wall during displacement of said piston unit in said flow channel when moved from its closing position to its opening position and vice-versa to clean said wall.