Flowing-down rainwater flow-separating pipe

DETAILED DESCRIPTION We claim: 1.
A flowing-down rainwater flow-separating pipe (13) comprising: an outer pipe (16) having a vertical portion (16d), connected at an upper end thereof to a rainwater flow passage (11) for receiving rainwater (15) dropping on a roof or a housetop of a building, and connected at a lower end thereof to a water collecting box (14) communicating with a sewer pipe, an inner pipe (18) arranged apart from an inner circumferential surface of the vertical portion (16d) at an outer circumferential surface of an upper portion thereof, and connected at a lower end thereof to any one of both of a storage-percolating box (17) for rainwater (15) or a storage vessel, and a ring-like flow-separating piece (24) disposed on the inner circumferential surface of the vertical portion (16d) of the outer pipe (16) above an upper end of the inner pipe (18) by a predetermined distance, wherein the flow-separating piece (24) comprises: a ring-like concave groove (24a) for receiving the rainwater (15) flowing down along the inner circumferential surface of the vertical portion (16d) of the outer pipe (16); a plurality of through holes (24b) formed on a bottom portion of the concave groove (24a) so as to be juxtaposed in a circumferential direction for guiding the rainwater (15) received in the concave groove (24a) to the water collecting box (14); and an inner circumferential wall (24c) formed in such a taper as that an inner diameter thereof decreases toward the lower end for guiding the rainwater (15) overflowing from the concave groove (24a) to the inner pipe (18).
2.
A flowing-down rainwater flow-separating pipe according to claim 1, wherein a slit (24d) crossing the through holes (24b) in the circumferential direction is disposed on the flow-separating piece (24), and an adjusting ring (26) which can adjust an opening ratio of the through holes (24b) is inserted rotatably into the slit (24d).
3.
A flowing-down rainwater flow-separating pipe according to claim 2, wherein a current piece (27) is disposed in the outer pipe (16) above the flow-separating piece (24) apart from the inner circumferential surface of the outer pipe (16), and the current piece (27) forms means to make the rainwater (15) flowing into the outer pipe (16) from the rainwater flow passage (11) to adhere and flow on the inner circumferential surface of the outer pipe (16)