Upper box body lifting device of positive and negative pressure poultry isolator

The upper box lifting device of the positive and negative pressure poultry isolator comprises an upper box and a lower box, the bottom of the lower box is fixedly connected with a function box, the interior of the function box is fixedly connected with a double-shaft motor, output shafts at the two ends of the double-shaft motor pair are both fixedly connected with rotating shafts, and the rotating shafts are fixedly connected with rotating shafts. First bevel gears are fixedly connected to the ends, away from each other, of the two rotating shafts, two threaded rods penetrating through the top wall of the functional box are rotatably connected to the inner wall of the bottom of the functional box, and second bevel gears in meshing transmission with the first bevel gears fixedly sleeve the peripheries of the bottom ends of the two threaded rods; the peripheries of the top ends of the two threaded rods are both sleeved with threaded cylinders in a threaded mode, the left side wall and the right side wall of th