Patent ID: 7360415
Filing Date: 2008-04-22
Classification: G01F

Abstract:
1. A thermal type air flow meter comprising: a first diaphragm-section and a second diaphragm-section which are comprised of respective cavity-portions and insulating diaphragms being formed at a semiconductor substrate; a thermal sensitive resistor for air-flow rate measurement being disposed on the first diaphragm-section; and an intake air temperature-measurement resistor being disposed on the second diaphragm section, wherein both planar shapes of the first diaphragm section and the second diaphragm section are respectively rectangles having short sides and long sides, wherein, the first diaphragm section and the second diaphragm section vary in size, and the thermal sensitive resistor for air-flow rate measurement on the first diaphragm and the intake air temperature-measurement resistor on the second diaphragm section have mutually different resistance patterns in shape and size, dimensions of the first and second diaphragm sections are set so that each size of the short sides of the second diaphragm section is 0.9 times to 1.1 times each length of the short sides of the first diaphragm section, and a distance from an edge of the first diaphragm section to the resistance pattern on the first diaphragm section in a short side direction of the first diaphragm section is substantially equal to a distance from an edge of the second diaphragm section to the resistance pattern on the second diaphragm section in a short side direction of the second diaphragm section.