Fuel injection pump for internal combustion engines

US5168847A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Hermann Grieshaber · Ingolstadt, DE
• Hans-Joachim Siebert · Schwieberdingen, DE
• Walter Egler · Stuttgart, DE
• Norbert Meissner · Neustadt, DE

Key dates

• Filing date: Mar 4, 1992
• Grant date: Dec 8, 1992
• Expiry date: Mar 4, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/12
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A fuel injection pump for internal combustion engines is proposed, in which to attain particularly quiet operation of an engine that is operated with direct injection, the fuel delivery is subdivided into a preinjection and a main injection; this injection is attained by annular groove, coinciding with one another, on the pump piston and pump cylinder, and a connecting groove connecting the coinciding annular grooves with a relief opening. After a partial stroke in the region of coincidence of the annular grooves with one another, the communication with the relief opening is interrupted again. The preinjection quantity can be kept particularly small here, with a short interval between the preinjection and the main injection; in combination with a two-spring-holder injection valve, this particularly small preinjection quantity can be kept constant to a great extent even at varying engine speeds, to attain an optimal reduction in combustion noise at various engine speeds.