Pressure regulating valve, control system of pressure regulating valve and smoke dust concentration measuring device with pressure regulating valve

The invention discloses a pressure regulating valve, a control system of the pressure regulating valve and a smoke concentration measuring device with the pressure regulating valve. The pressure regulating valve comprises a valve body and a valve seat arranged in the valve body, the valve seat is internally provided with a pressure regulating cavity extending in the first linear direction, and the pressure regulating cavity is provided with an air inlet end penetrating through the valve seat and an air outlet end opposite to the air inlet end; the air inlet end and the air outlet end are communicated with the outside; the pressure regulating valve further comprises an adjusting rod, the adjusting rod is of a hollow structure, the adjusting rod and the pressure adjusting cavity are coaxially arranged, the adjusting rod is provided with a stretching-in end penetrating into the pressure adjusting cavity from the air outlet end, an air outlet gap is formed between the peripheral face of the stretching-in end and