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:
Nov. 28, 1989
Filed:
Feb. 27, 1987
James A Zboralski, Clawson, MI (US);
Darryl A Hock, Harper Woods, MI (US);
David L Kaleita, Hamtramck, MI (US);
Jabil Circuit Company, Madison Heights, MI (US);
Abstract
The airflow sensor uses a flow sensing bridge having a thermal element which senses airflow as a function of electrical energy applied to the bridge. Energy is applied to the bridge to maintain the thermal element at a constant temperature and constant resistance. A differential amplifier monitors the balanced and unbalanced state of the bridge and controls the application of energy to the bridge to maintain a balanced state. A microcomputer with analog to digital converter senses the level of energy applied to the bridge and converts this energy level to a digital signal indicative of airflow. The raw digital signal is corrected using calibration lookup tables and thermal compensation correction tables in the microcomputer memory circuits. The microcomputer outputs a variable frequency signal indicative of the measured mass airflow. In the alternative to the differential amplifier, the bridge may be balanced using the microcomputer in a sample and hold voltage to current converter configuration.