Patent ID: 8398302

Claim:
A temperature sensor including a temperature sensitive device which is disposed in a flow path through which fluid flows and whose electric characteristic changes as a function of temperature of the fluid in the flow path, signal lines connected at top end sides thereof to said temperature sensitive device through electrode wires and at base end sides thereof to lead wires for connection with an external circuit, a sheath member retaining the signal lines therein, and a holding member which holds an outer circumferential surface of said sheath member directly or indirectly through another member, wherein a protruding length L 1 that is a distance between an inner circumference of said flow path on an axis of the temperature sensor and a center of said temperature sensitive device is 50 mm or more, and if a protruding location that is a distance between an inner circumferential surface of the flow path and a center of said temperature sensitive device on a cross section extending perpendicular to an axis of the flow path through the center of said temperature sensitive device is defined as L 1 ′, and a flow path width that is a distance between intersections of the axis of the temperature sensor with the inner circumferential surface of the flow path when the temperature sensor is projected onto said cross section is defined as D 1 , a relation below is met: L 1 ′/D 1≧{0.6−(1/1000)× D 1} when 100 mm≦ D 1<200 mm, L 1 ′/D 1≧{0.74−(1/600)× D 1} when 200 mm≦ D 1<300 mm, or L 1′/ D 1≧0.24 when 300 mm≦ D 1. a percent error of the temperature sensitive device is maintained below a predetermined value, wherein the percent error is 15% or less.