Retainer cone and bug filter retainer having the same

Intended is to provide a retainer cone, which is inserted into the center of the upper end portion of a retainer body, which is a negative pressure generating region near the mounting position of a conventional Venturi tube, to disperse a portion of such compressed air radially of the retainer body as is injected from a nozzle at the upper portion of the retainer body at the time of back-washing a filter fabric, so that it can prevent a negative pressure from being generated on the upper end side of the retainer body, which bulges the entire filter fabric containing the upper end side of the retainer body outward so that it can reliably wipe off powder dust having stuck to the filter fabric, and which makes the sectional area of the passage of the retainer body upper end portion larger than that of the conventional Venturi type so that it can drastically reduce the load on a blower to be used for suctions at the dust collecting time. The retainer cone is inserted into and arranged at the central portion on the upper end side of the retainer body for a bug filter retainer, and includes a radially reduced upper end portion so formed at the upper end portion of the longitudinal direction as is radially reduced toward the upper end, and a radially reduced lower end portion so formed at the lower end portion of the longitudinal direction as is radially reduced toward the lower end.