Abstract: An ultraviolet irradiation unit of the present invention includes a casing, a light source emitting ultraviolet rays arranged in the casing, an ultraviolet transmitting body arranged between an ultraviolet emission opening of the casing and the light source. The casing has an outer diameter dimension that enables the casing to fit within a bore of a joint connected to a flow channel pipe.

Abstract: A sterilization device includes: a reservoir, a supply port, an output port and a light source. The reservoir part includes a first half reservoir part having a substantially hemispherical shape and located on an upstream side in a flow direction of the fluid at the supply port, and a second half reservoir part having a substantially hemispherical shape and located on a downstream side in the flow direction. The supply port opens to the first half reservoir part. The output port opens to the second half reservoir part. When the supply port and the output port are projected on a virtual plane orthogonal to an extending direction of an inner surface of a supply channel connected to the reservoir part at the supply port, a center of gravity of the supply port and a center of gravity of the output port are separated from each other.

Abstract: An ultraviolet irradiation unit of the present invention includes a casing, a light source emitting ultraviolet rays arranged in the casing, an ultraviolet transmitting body arranged between an ultraviolet emission opening of the casing and the light source. The casing has an outer diameter dimension that enables the casing to fit within a bore of a joint connected to a flow channel pipe.

Abstract: A resin gear includes a web with a side surface on which a first annular rib and a second annular rib are formed to be concentric with a boss. The web has an inner web portion coupling the first annular rib to the second annular rib, and an outer web portion coupling the second annular rib to a rim. The inner web portion is formed to have a thickness gradually reduced from one intersection point toward another intersection point, the intersection points being intersection points of a virtual radial direction line passing through a center of the boss with the second annular rib. The first annular rib has a side surface on which only one gate mark of an injection molding is formed at a position on a radially outer side with respect to a first tooth portion and a position biased to the other intersection point on the virtual radial direction line.

Abstract: A resin gear includes a web with a side surface on which a first annular rib and a second annular rib are formed to be concentric with a boss. The web has an inner web portion coupling the first annular rib to the second annular rib, and an outer web portion coupling the second annular rib to a rim. The inner web portion is formed to have a thickness gradually reduced from one intersection point toward another intersection point, the intersection points being intersection points of a virtual radial direction line passing through a center of the boss with the second annular rib. The first annular rib has a side surface on which only one gate mark of an injection molding is formed at a position on a radially outer side with respect to a first tooth portion and a position biased to the other intersection point on the virtual radial direction line.