The utility model provides a to advance support brill hole area, carries out the device of safe dust fall among a small circle, the roof both ends are arranged respectively in to two pterygoid lamina one end of its characterized in that, two pterygoid laminas are parallel to each other, and two are removed on the wheel arranges two pterygoid lamina other ends in through the back shaft correspondence respectively, the pterygoid lamina embeds there is flank air draft cavity, inboard the opening of pterygoid lamina has a plurality of mounting holes, a plurality of flank filter screens correspond respectively arrange a plurality of mounting holes in, on the roof is arranged respectively in to two flank fans, and correspond through the exhaust column respectively and be linked together with two flank air draft cavity, the roof is built -in to have a top air draft cavity, on the roof is arranged in to the top filter plate, and is located top air draft cavity under, on the roof is arranged in to the top fan, just and top air draft cavity be linked together, communicating pipe is linked together with two flank fans, top fan respectively.