The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 09, 1985
Filed:
Oct. 25, 1983
Jeffrey S Gutterman, Hilton, NY (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A fluid flow meter and, more especially, an airflow meter having fast response and very high resolution uses piezoelectric transducers operating near resonance to pass ultrasonic signals upstream and downstream alternately in a flow passage. Transmission signals continue longer than the propagation time to the receiver so that the phase of the received signals can be compared to the transmission signals. The difference of upstream and downstream phase differences is a measure of the air velocity while the sum of those phase differences is useful to determine air temperature. These values along with an air pressure sensor reading are combined to determine mass airflow through the passage. The acoustic transducers are operated near resonance to optimize signal-to-noise ratio. Readings from the initial reception period of each transducer are ignored to avoid the effects of ringing of the transducer from each previous transmission cycle and to allow the receive signal to build up resonance with the acoustic signal.