| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a gas sensor measuring the property of gas using a detecting vibration element such as an ultrasonic element, that a detection error is caused due to influence such as thermal expansion of a resin filling the interior of a case where the ultrasonic element is disposed. SOLUTION: The inner peripheral surface of an element case 42 of the gas sensor 10 is formed as a tapered surface 100 having an angle of about 11 degrees to the vertical direction, and a part surrounded with the taper surface 100 and a protective film 48 of a storing part 43 is filled with a filler 49 which is a polyurethane. As a result, when the polyurethane foam is thermally expanded at a high temperature, the upward component force is received by the tapered surface 100 so that the influence of volume change due to expansion is hardly exerted toward the protective film 48. Accordingly, the projection of an element part 44 causing the deformation of the protective film is restrained, and the changeΔL in the propagation distance L to the reflecting part 33 is also restrained not to lower the detection accuracy. Further, reverberation which is the damped vibration after the ultrasonic element 51 is driven is shortened. The lower part of the tapered surface 100 may be formed as a curved surface. COPYRIGHT: (C)2004,JPO
|
