One-way fresh air purification and exhaust all-in-one machine

The utility model discloses a one-way fresh air purification and exhaust all-in-one machine, which relates to the field of fresh air machines and comprises a main outer shell, an outdoor air inlet flange is fixedly connected to the inner side edge of the main outer shell through bolts, and air inlet inner and outer circulation valves are symmetrically arranged on the inner side edge of the main outer shell. A primary effect aluminum frame nylon net is horizontally and fixedly arranged on the inner side edge of the main outer shell, a medium effect is horizontally and fixedly connected to one side edge of the primary effect aluminum frame nylon net in a clamped mode, a high effect is horizontally and fixedly connected to the inner side edge of the main outer shell in a clamped mode, and a direct current motor is fixedly connected to the inner side edge of the main outer shell through bolts. A PTC auxiliary heater is fixedly connected to the inner side edge of the main outer shell through bolts, an air outlet i