US Patent 10203048 Automatic drain discharge apparatus

An automatic drain discharge utilizing a vertically movable float to activate a diaphragm of a pilot valve to drive a drain plug. The inner diameter at the bottom of a case is gradually decreased from upper to lower positions. A bottom surface of a communication hole of a drain housing provided in an opening of the case has an inclined surface inclined toward a drain discharge hole. An outer marginal portion which is positioned at the uppermost position in the bottom surface of the communication hole is in the same plane as or lower than a marginal portion which is positioned at the lowermost position in an inner circumferential surface of the case and adjacent to the opening.