Air flow rate meter

US5301547A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Bernd Osswald · Mertingen, DE
• Thomas Schwegel · Lambach, DE
• Hans-Peter Stiefel · Ditzingen, DE

Key dates

• Filing date: Sep 23, 1992
• Grant date: Apr 12, 1994
• Expiry date: Sep 23, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G01F15/00
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A flow rate meter for determining the mass or flow rate of flowing air, having a temperature-dependent measuring resistor disposed in an air bypass conduit. The air bypass conduit has a convergent portion in the region of the measuring resistor in which the air flow is accelerated. As a result of the air flow the effects of any air disturbances upon the measuring element are reduced. The following geometric relationships are advantageous: l.sub.1 /l.sub.s >3.8, l.sub.1/2 >1.5, l.sub.1 /1.sub.3 >2.0, l.sub.1/4 >9.0, l.sub.5 /l.sub.s >1.5, l.sub.5 /l.sub.6 =1.7 to 1.9, b.sub.1 /b.sub.s >40.0, b.sub.1 /b.sub.2 >2.0, l.sub.1 /b.sub.1 >3.5, and l.sub.5 /b.sub.3 =5.5 to 6. The air flow rate meter is especially suitable for determining the mass or flow rate of aspirated air in mixture-compressing engines with externally supplied ignition as well as air-compressing, self-igniting engines.