Air pressure self-adjusting safety valve

The utility model discloses an air pressure self-adjusting safety valve. A through hole is arranged in the middle of a large end of a valve body 2, inner threads are processed at the head of the large end, full outer threads are processed at a small end of the valve body 2, a cylindrical guiding rod P is arranged at the center of the upper end surface of a guiding sealing cover 1, an annular sealing groove is disposed on the lower end surface of the guiding sealing cover 1, a sealing ring 6 is mounted in an annular sealing groove, a concave position in the middle of the sealing ring is correspondingly arranged on an annular projection of a step surface in the valve body, the guiding sealing cover is mounted in the valve body and is connected with the annular projection of the step surface in the valve body via the sealing ring 6 in an abutted manner, then a combined spring 5 is sleeved in the guiding rod, a guide barrel at the center of a pre-tightening guiding cover 3 is screwed into the valve body after mat