Air flow rate metering instrument

US4252016A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Rudolf Sauer · Memmingen, DE
• Heinz Gneiss · Ludwigsburg, DE
• Peter Romann · Stuttgart, DE

Key dates

• Filing date: May 24, 1979
• Grant date: Feb 24, 1981
• Expiry date: May 24, 1999

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01C13/00
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A flow rate meter, especially for measuring the air flow rate in the intake of internal combustion engines, in which a heatable wire is located for exposure to the air stream. A controller maintains the temperature or resistance of the heated wire constant, thereby permitting a determination of the air flow from the current required in the control process. In order to prevent internal stresses in the wire due to varying expansion, the two ends of the wire are firmly mounted in a support structure while at least one intermediate part is looped loosely around an intermediate support point. In order to prevent uncontrollable heat transfer from the loop to the third support point, the wire is electrically joined at the point where the parts of the wire forming the loop cross one another, thereby preventing electrical current from flowing in the loop. Furthermore, the sensitive parts of the wire lie in the main flow and do not closely approach the wall of the structure.