Glow plug, particularly for diesel engine

US4418661A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Friedrich Esper
• Thomas Frey · Friolzheim, DE
• Heinz Geier · Leonberg, DE
• Gerhard Holfelder · Ditzingen, DE
• Gunther Knoll · Stuttgart, DE

Key dates

• Filing date: May 27, 1981
• Grant date: Dec 6, 1983
• Expiry date: May 27, 2001

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02B3/06
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

To decrease the preheat time and power requirements in preheater-type glow plugs for Diesel engines, a closed ceramic tube (20), for example of aluminum oxide and of about 5 mm diameter has, on the bottom (21) thereof applied a layer or film-like heater element (24, 24'), for example in an undulating or zig-zag configuration (FIG. 2) or in form of a constriction or pinch (FIG. 4: 24') to provide a concentrated point or strip source of heat. The heater layer itself is protected by a protective coating (25) and, to provide for the required heat distribution, the underlying bottom (21, 21') of the tube (20, 20') supports an insulating intermediate layer and possibly a heat conductive layer is intermediate. Preheat times in the order of 1-2 seconds, with lower current consumption than prior wound-wire plugs can be obtained.