Variable gap back flush filter

The utility model relates to a variable gap back flush filter, include a filter shell, the filter shell includes the casing, and the casing lower extreme has a low head, and the other end is connected with a takeover, is connected with an upper cover at the other end of taking over, and it has the anti - mouth of arranging of feed liquor to open on the low head, has the liquid outlet in the takeover, a filter spare, including a skeleton and upper and lower locating plate, it has the filtration pore to distribute on the skeleton, and end, end cap are installed to the both ends of skeleton, and closing cap is down installed to the one side that lies in the end at the skeleton, is close to end cap one side cover at the skeleton and is equipped with the upper cover, and the circumferential surface of skeleton goes up to overlap and is equipped with the extension spring, installs upper and lower holding ring in the extension spring, a direction subassembly, the direction subassembly includes guide bar and last, lower limit plate, a drive assembly, drive assembly include a driving cylinder. The utility model has the advantages of: the utility model provides a filter can carry out automatically regulated according to the size of impurity, can the effectual impurity of cleaing away on the filter screen, improve the life of filter.