Peter J Harper

US Patent:

49470574, Aug 7, 1990

Filed:

May 1, 1989

Appl. No.:

7/345815

Inventors:

Walter S. Czarnocki - Schaumburg IL
Peter W. Harper - Crystal Lake IL
Kevin S. Moran - Algonquin IL
Steven W. Alexander - Schaumburg IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H01L 2716

US Classification:

307310

Abstract:

A mass fluid flow sensor is disclosed which utilizes a sensing bridge circuit to develop a sense (control) signal related to fluid flow. A fluid temperature variable resistor, separate from said bridge circuit, is utilized to implement temperature compensation so that a desired output signal is a function of sensed fluid flow, but is less dependent on fluid temperature than the sense (control) signal provided by the bridge circuit. A resistor in the bridge circuit is selected such that the sense (control) signal provided by the bridge circuit has a rate of change as a function of flow rate substantially independent of fluid temperature, but this sense signal still varies as a function of fluid temperature. This permits fluid temperature compensation of the bridge sense signal in a noncomplex and cost effective manner. An improved adjustable circuit (36-41) is provided for producing a desired temperature variable output signal (V. sub. os).

US Patent:

48541672, Aug 8, 1989

Filed:

Sep 9, 1987

Appl. No.:

7/094953

Inventors:

Walter S. Czarnocki - Schaumburg IL
Peter W. Harper - Crystal Lake IL
Kevin S. Moran - Algonquin IL
Steven W. Alexander - Schaumburg IL

Assignee:

Motorola Inc. - Schaumburg IL

International Classification:

G01F 168

US Classification:

7320419

Abstract:

A mass fluid flow sensor is disclosed which utilizes a sensing bridge circuit to develop a sense (control) signal related to fluid flow. A fluid temperature variable resistor, separate from said bridge circuit, is utilized to implement temperature compensation so that a desired output signal is a function of sensed fluid flow, but is less dependent on fluid temperature than the sense (control) signal provided by the bridge circuit. A resistor in the bridge circuit is selected such that the sense (control) signal provided by the bridge circuit has a rate of change as a function of flow rate substantially independent of fluid temperature, but this sense signal still varies as a function of fluid temperature. This permits fluid temperature compensation of the bridge sense signal in a noncomplex and cost effective manner.