Auxiliary filtering device of air respirator for fan gearbox

The utility model relates to an auxiliary filtering device of an air respirator for a fan gearbox. The device is characterized by comprising a hollow annular pipe (8), the hollow annular pipe (8) is respectively communicated with all air inlets (10) of the air respirator, the hollow annular pipe (8) is further communicated with an external filtering type oil cup through a connecting pipe (6), the external filtering type oil cup comprises an oil storage cup (1), lubricating oil (2) is placed in the oil storage cup (1), and the device further comprises an oil cup cover partially inserted into the lubricating oil (2). The oil cup cover comprises a round cover plate (4), at least one through hole (5) is formed in the edge of the round cover plate (4) so that external air can be communicated with lubricating oil (2) in an oil storage cup (1), and a breather pipe (3) is fixedly installed in the middle of the round cover plate (4). After the device is adopted, double filtration of dust and water is realized, oil pol