To provide an atmospheric pressure type vacuum breaker, and a flush toilet bowl using this vacuum breaker capable of draining water when used in a cold district, reducing a pressure loss when feeding water, and superior in negative pressure breaking performance.
This atmospheric pressure type vacuum breaker has a water passage having a water inlet port and a water outlet port, an atmosphere introducing port for introducing the atmosphere to the water passage, a movable valve element for introducing the atmosphere to the water passage from the atmosphere introducing port when feeding no water, and blocking up the the atmosphere introducing port when feeding the water by moving by water force in the water passage, and is characterized in that the movable valve element has a movable valve element abutting part formed of an elastic body for hiding the water inlet port by abutting when feeding no water, and the movable valve element forms a passage with the water inlet port in a state of abutting on the water inlet port, and the movable valve element abutting part is deformed and reduces the area of the passage according to an increase in a negative pressure value when negative pressure is generated on the water inlet port side.
TSUTSUI HARUO
KUBOZONO YUKINORI
WATANABE AKIRA
MIZOGUCHI WAKICHI
