Air-fuel mixer and combustion system

A mixer disposed in a fuel gas combustion system and mixing air and fuel gas to form flammable mixed gases, the mixer comprising:

• a Venturi tube having an air inlet, a fuel gas inlet, a gas mixture outlet, a central axis direction, and a throat positioned between the air inlet and the gas mixture outlet in the central axis direction, wherein the fuel gas inlet is disposed at the throat;
• and
• an adjustment component disposed in the Venturi tube downstream of the throat, the adjustment component drivable to move towards or away from the throat in the central axis direction, thereby changing a flow area of gas in the Venturi tube;
• wherein the adjustment component includes a conical valve plug with a conical outer surface thereof at a side facing towards the throat and fitting an inner surface of the Venturi tube at the throat;
• a drive mechanism for driving the adjustment component, wherein the drive mechanism includes:
• a central shaft positioned in the Venturi tube to reciprocate in the central axis direction, the adjustment component being fitted around and fixed to the central shaft;
• and a transmission assembly having a first end connected to the central shaft and a second end connected to an actuator, the transmission assembly impelling the central shaft to move under the driving action of the actuator;
• wherein the transmission assembly includes:
• a transmission shaft extending in a direction perpendicular to the central axis direction and rotating under the driving action of the actuator;
• and a shaft levering device having a first end connected to the transmission shaft in a fixed manner and a second end connected to the central shaft;
• wherein the transmission shaft rotates and drives the shaft levering device, the shaft levering device in turn pushing the central shaft to move linearly along the central axis;
• the shaft levering device is fitted around the transmission shaft in a fixed manner;
• the shaft levering device has two lever parts extending in a direction perpendicular to the transmission shaft;
• the two lever parts are spaced apart parallel to one another and configured such that the central shaft is adapted to be positioned therebetween;
• each lever part having a slot hole in a length direction thereof;
• the mixer further comprises a connecting rod adapted to pass through the slot holes of the two lever parts and a through-hole in the central shaft positioned between the two lever parts, the connecting rod parallel to the transmission shaft.