Rich-Lean Burner

Abstract

A rich-lean burner with a lean flame port, a blind clearance, and a rich flame port has: a burner main body with a pair of burner-main-body side plates on both lateral sides thereof; a burner cap with a burner-cap side plate covering the burner main body from at least one lateral outside thereof; and a straightening member with straightening plates to divide the lean flame port into laterally disposed zones. Upper ends of the burner-main-body side plates are below upper ends of the burner-cap side plate and of the straightening plates. The straightening member has a partition plate which is located laterally outside an outer straightening plate contiguous to the blind clearance and which extends upward beyond the burner-main-body side plates. The blind clearance is defined between the partition plate and the outer straightening plate, and the rich flame port is defined between the partition plate and the burner-cap side plate.

What is claimed is: 
     
         1 . A rich-lean burner comprising, on an upper end portion thereof: a lean flame port longitudinally extended to eject a lean fuel/air mixture which is leaner in fuel concentration than a theoretical fuel/air ratio; a blind clearance located on at least one lateral side of the lean flame port, the blind clearance being free from ejection of a fuel/air mixture; and a rich flame port located laterally outside the blind clearance thereby ejecting a rich fuel/air mixture which is richer in fuel concentration than the theoretical fuel/air ratio,
 the rich-lean burner including constitutional elements of: a burner main body having a pair of burner-main-body side plates lying opposite to each other on both lateral sides of the burner main body; a burner cap having a burner-cap side plate covering the burner main body from at least one lateral outside thereof; and a straightening member mounted between both the burner-main-body side plates and having a plurality of straightening plates to divide the lean flame port into a plurality of laterally disposed zones,   characterized in: that an upper end of each of the burner-main-body side plates is below an upper end of the burner-cap side plate and an upper end of each of the straightening plates; that the straightening member has a partition plate located laterally outside an outer straightening plate, among the plurality of straightening plates, that is contiguous to the blind clearance, the partition plate extending upward beyond the burner-main-body side plates, that the blind clearance is defined between the partition plate, and the outer straightening plate; and that the rich flame port is defined between the partition plate and the burner-cap side plate.   
     
     
         2 . The rich-lean burner according to  claim 1 , wherein the straightening member further comprises bridge portions arranged at a plurality of longitudinally separate positions, each of the bridge portions connecting an upper end of the partition plate and an upper end of the outer straightening plate. 
     
     
         3 . The rich-lean burner according to  claim 2 , wherein the straightening member further comprises constricted portions at longitudinally separated positions that coincide with the bridge portions, the constricted portions being arranged by laterally bringing the plurality of straightening plates into intimate contact with one another, thereby longitudinally dividing the lean flame port. 
     
     
         4 . The rich-lean burner according to  claim 3 , wherein the burner cap comprises: a pair of side plates to cover the burner main body from an outside of laterally one side and from an outside of laterally opposite side; and bridge portions disposed at a plurality of longitudinal positions to connect upper ends of both the side plates, wherein each of the burner-cap bridge portions is disposed at longitudinal positions coinciding with each of the straightening-member bridge portions in contact with a top of each of the straightening-member bridge portions.