PURPOSE: To improve the decrease of the concentration of flue gas/HC in an engine and the fuel consumption by arranging a glow plug through the process of protruding a heat generating part to be rotated by means of an actuator on a vortex chamber, and advancing and retreating the heat generating part in relation to the inside of the vortex chamber according to the engine speed.

CONSTITUTION: In an engine 1, vortex flow is given to air to flow into a vortex chamber 6 from a main chamber C side through a nozzle hole 4 on a mouthpiece 3. And air-fuel mixture is produced by stirring fuel to be injected from a nozzle 9 in vortex, thereby the combustion expansion is started. Moreover air-fuel mixture in the combustion expansion is injected into the main chamber C from the nozzle hole 4, and the combustion is completed. In this case, a heat generating part to be driven by an actuator is protruded on the vortex chamber 6 so as to arrange a glow plug 8. And the actuator of the glow plug 8 is drive- controlled by a control means 10 according to the engine speed Ne. That is, the heat generating part is retreated from the vortex chamber 6 when the engine speed is low, while it is advanced to the vortex chamber 6 when the engine speed is high.