BALL CIRCULATING TYPE FLOW-RATE SENSOR

PURPOSE:To provide a ball circulating type flow-rate sensor which is designed to cause a ball to stably circulate, without being stalled, through a circular passage even at a low flow-rate by providing the tip of an orifice in the direcion of the tangent line of the circular passage and also providing the opening of a discharge passage at the same position as that of the tip of the orifice. CONSTITUTION:An inflow passage 11, an outflow passage 12 and a circular passage 13 are formed in an outlet body 21 and an inlet body 22 and the tip of an orifice 14 is provided at a position where it becomes tangent with the outer circumference of the circular passage 13. A ball 13 is inserted into the circular passage 13 and a light emitting element 23 and a light receiving element 24 which are airtightly covered with seals 32, 32 are installed to transparent windows 32, 32 provided, over the circular passage, on the outlet body 21 and the inlet body 22 respectively. Due to this constitution, liquid flowing into the inflow passage 11 becomes jet stream by the orifice 14, causing the ball 13 to circulate inside the circular passage 13, and flows out through an outflow port 16 provided at the same position as the tip of the orifice of the outflow passage 12, therefore the flow-rate of liquid can be obtained by sensing the circulation of the ball 13 with the light emitting element 23 and the light receiving element 24.