First-stage and second-stage filtering device

The utility model discloses a first-stage filtering device and a second-stage filtering device which are arranged at an exhaust port of a screw rod of an exhaust main engine, and gas pumped out by the screw rod is dirty and contains a large amount of impurities such as moisture, oil, dust particles and the like, so that the gas needs to be filtered firstly; impurities such as water, oil, dust particles and the like extracted from the exhaust main engine screw enter the barrel body through the air inlet, and then most of the impurities such as water, oil, dust particles and the like extracted from the main engine screw are filtered out through the first-stage filtering and the second-stage filtering in sequence; relatively clean gas after being filtered enters the next filtering system or enters the vacuum pump through the gas outlet, so that the air entering the vacuum pump is ensured to be sufficiently clean after being filtered, the vacuum degree can be effectively ensured under the condition that the vacuu