BREATHER PLUG

摘要

A breather plug mounted to a case and releasing the inside of the case to the atmosphere is provided with a housing having a fluid path. When the breather plug is being mounted to the case, one end of the fluid path communicates with the inside of the case and the other end is open to the atmosphere. The fluid path of the housing is provided with a large-diameter section communicating with the inside of the case and a small-diameter section located on the atmosphere side of the large-diameter section and connecting to the large-diameter section with a step located in between. The step between the large-diameter section and the small-diameter section is formed in a reversely tapered shape in which the diameter increases from the inside of the case to the atmosphere side. Such a step having the reversely tapered shape in the fluid path produces turbulence in airflow in the fluid path, producing stagnation of the airflow in the periphery of the step to cause oil mist to drop by the weight of the oil mist. As a result, leakage of the oil mist to the outside is suppressed.