Electrically controlled fuel injection system

US4058089A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Peter Schmidt · Schwieberdingen, DE
• Helmut Worz

Key dates

• Filing date: Sep 18, 1975
• Grant date: Nov 15, 1977
• Expiry date: Sep 18, 1995

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02D41/187
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A fuel injection system for an internal combustion engine includes an electronic fuel controller which accepts signals representative of the air flow rate through the engine's induction tube as well as data relating to rpm and other parameters. The air flow rate data is derived from an electrically heated wire, located in the induction tube, which is connected in one branch of a bridge circuit. Changes in the air flow rate result in changes of heat transfer and hence of the temperature of the heated wire whose impedence changes accordingly. A control loop senses the imbalance of the currents in the two branches and acts to restore equilibrium, e.g. by increasing the total bridge current until a higher heat loss from the wire has been compensated. The increased bridge current is provided by periodic current pulses delivered by transistors under the control of a multivibrator. The multivibrator is triggered at a frequency which is a function of the imbalance signal voltage.