| 摘要 |
A nozzle has a tubular metal core which forms a central injection duct, and a cylindrical, outer, lateral surface. A heater/diffuser device includes a metal heat diffuser of tubular cylindrical shape with an open annular cross-section, mounted around the cylindrical surface of the core. The diffuser has: a cylindrical internal surface fitting the cylindrical surface of the nozzle core, two facing longitudinal free edges which are spaced apart circumferentially, are free of one another, and define between them a longitudinal space extending along a generator line of the cylindrical surface of the diffuser, and a recessed, channel-like seat formed in a surface of the diffuser element. A resistor is housed in the channel-like seat. The distance between the longitudinal free edges is such that, when the nozzle unit is heated by the supply of electrical current through the resistor, the diffuser is free to expand thermally by extending in the circumferential direction around the nozzle without moving radially away from the outer surface of the nozzle core.
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