| 摘要 |
PURPOSE:To improve thermal efficiency and to reduce a production cost by a method wherein the composite angle of pilot methanol spray satisfies a specified expression while an inter-center distance between the nozzle of an auxiliary fuel value and a glow plug and a diameter of a nozzle satisfy a specified expression. CONSTITUTION:The axis CC1 of a nozzle for pilot spray C1 passing the nozzle center phi1 of an auxiliary fuel valve 1 and the axis CC2 of the nozzle for a pilot spray C2 have respective projections on a horizontal plane which are overlapped with each other. The axis CC1 has an upward angle thetaC1 to a horizontal line H1 passing through the tip of the nozzle and the axis CC2 has a downward angle thetaC2 to the horizontal line H1, and satisfy a condition of 20 deg.C<=(thetaC1+thetaC2)<=37.5 deg.. Nozzles for pilot sprays D1 and D2 from an auxiliary fuel valve 2 are formed in a similar manner described above. Provided a distance between the nozzle centers phi1 and phi2 of the auxiliary fuel valves 1 and 2 to the centers of glow plugs 3 and 4 is L and a diameter of a nozzle is dn, the glow plugs 3 and 4 are mounted so that an expression of 55<=(L/dn)<=120 is eastablished. This constitution performs reliable ignition of methanol spray, improves thermal efficiency, and reduces a production cost.
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