Abstract: A rich-lean flame burner having on an upper part thereof: a longitudinally elongated lean burner port; and a rich burner port lying adjacent to at least one lateral side of the lean burner port with a clearance therebetween. At a plurality of longitudinal points of straightening members having a plurality of straightening plates which divide the lean burner port into a plurality of laterally sectioned regions, there are disposed first constricted portions which bring upper parts of the straightening plates into intimate contact with each other. Second constricted portions are disposed in at least laterally outermost straightening plates to further divide each portion of the lean burner port that has been divided by the first constricted portions. The second constricted portions are such that the lower end thereof is positioned above the lower end of the first constricted portions, and that the vertical length is shorter than the first constricted portions.

Abstract: A rich-lean flame burner having on an upper part thereof: a longitudinally elongated lean burner port; and a rich burner port lying adjacent to at least one lateral side of the lean burner port with a clearance therebetween. At a plurality of longitudinal points of straightening members having a plurality of straightening plates which divide the lean burner port into a plurality of laterally sectioned regions, there are disposed first constricted portions which bring upper parts of the straightening plates into intimate contact with each other. Second constricted portions are disposed in at least laterally outermost straightening plates to further divide each portion of the lean burner port that has been divided by the first constricted portions. The second constricted portions are such that the lower end thereof is positioned above the lower end of the first constricted portions, and that the vertical length is shorter than the first constricted portions.