Patent ID: 9669335
Date: 2017-06-06
CPC Classifications: B01D

Claim:
1. A filter apparatus comprising: a casing comprising: a backwash slide member is provided inside the cylindrical filter element in a manner such that an outer circumferential portion of the backwash slide member slides in contact with an inner circumferential surface of the cylindrical filter element, wherein the backwash slide member is capable of moving backward and forward in an axial direction of the cylindrical filter element, and wherein the backwash slide member is capable of removing trapped matter adhering to the inner circumferential surface of the cylindrical filter element by means of an inward flow generated by a difference in pressure inside and outside the cylindrical filter element at a time of backwashing; a backwash pipe that comprises a first end, a second end, and a fluid flowing passage extending from the first end to the second end, wherein the first end is connected to a side surface of the backwash slide member, wherein the second end is connected to a piston member, wherein the second end is provided with at least one aperture portion at a location in contact with the fluid flowing passage, wherein the aperture portion comprises an opening that is smaller than a cross-sectional area of the fluid flowing passage, and wherein the backwash pipe allows the inward flow generated in the backwash slide member to flow toward the drain chamber; an actuation cylinder that comprises a first closed end, which is closed by a closing member and is passed through by the backwash pipe, and a second open end, wherein the piston member is fitted from the closed first end of the actuation cylinder in a manner such that the piston member is capable of moving backward and forward to therefore move the backwash slide member backward and forward inside the cylindrical filter element, and wherein the open second end of the actuation cylinder extends into the drain chamber to allow the fluid from the backwash pipe to flow toward the drain chamber and into the drain outlet; and a fluid flowing channel through which an inside of the actuation cylinder is communicated with an outside of the casing in order to allow a fluid to flow into and out of the actuation cylinder to enable the piston member to move backward and forward inside the actuation cylinder, wherein the pressure at the fluid outlet is set to be higher than atmospheric pressure, the pressure at the fluid inlet is set to be higher than the pressure at the fluid outlet, and wherein the drain outlet is opened and closed to lower the pressure of the drain chamber compared to the fluid outlet, to carry out the backwashing.