| 摘要 |
PURPOSE:To check the infiltration of foreign matters into an introduction part by arranging a lid body in which an opening is formed to intorduce a fluid to be detected to the center of an introduction port in such a manner as to cover the introduction port and a barrier which guides all of the fluid into the introduction part as being detected flowing into the lid body. CONSTITUTION:Light from a light emitter 30 passes through both openings 22b and 22c of a cylinder 22 and becomes a reception signal with a light receiver 40. Now when a vehicle is run, as a dust fluid is being introduced into an introduction hole 21 from an opening 21a passing through a fluid introduction member 50, the quantity of light received with the light receiver 40 reduces according to the density of the dust fluid and the value of the received light signal from the light receiver 40 decreases. Even though entering the introduction hole 21 together with the dust fluid, foreign matter such as fine particles in mud, water or the like attach onto the upper wall 52a of an insert 52 and as the infiltration thereof is checked, the dust fluid alone is introduced into the cylinder 22 as cleared of the foreign matters. Thus, the value of the light reception signal of the light receiver 40 can be obtained at a high accuracy corresponding only to the density of the dust free from the effect of the foreign matters on the reduction in the quantity of light received with the light receiver 40. |
