Throat-diameter-variable safety valve

The utility model discloses a throat-diameter-variable safety valve. The throat-diameter-variable safety valve comprises an outer shell, a main spring mechanism, an auxiliary spring mechanism, a connector, a main valve disk and an auxiliary valve disk. The lower end of the outer shell is connected to a valve mouth in a sleeving mode. The main spring mechanism, the auxiliary spring mechanism, the connector, the main valve disk and the auxiliary valve disk are arranged in the outer shell. The upper half part of the connector is a closed part, and the lower half part of the connector is an open part. The top of the connector is fixedly connected with the main spring mechanism, and the bottom of the connector is fixedly connected with the main valve disk. The bottom of the auxiliary spring mechanism is fixedly connected with the auxiliary valve disk. According to the throat-diameter-variable safety valve, by additionally arranging the auxiliary spring mechanism and the auxiliary valve disk in the safety valve, the set pressure of a main valve disk mechanism and the set pressure of an auxiliary valve disk mechanism are set to be unequal, and therefore two discharge channels with different rated flows are formed; accordingly, the safety of the safety valve can be guaranteed, and the problems of trembling and chattering of the valve disks are also avoided.