| abstract |
A method of manufacturing an exhaust control valve includes casting first and second subhousings as separate pieces and machining smooth the inner faces of both. Each subhousing has a stem portion and a flow portion. Each flow portion defines a cylindrical bore from which a seat arc extends radially inward and approximately 180° along. The seat arc of the first subhousing lies below, and the seat arc of the second subhousing lies above, a horizontal plane that bisects the subhousings. Each seat arc has a semicircular inner sidewall that serves as a valve seat. Their inner faces facing each other, the two subhousings are mated so that their two stem portions form a stem housing and their two flow portions form a flow housing. During the mating step, the cylindrical bores are aligned to form a flow passage through the flow housing, with the two valve seats spaced equidistantly from a vertical plane defined by the inner faces along which the subhousings mate. In further steps, the method involves boring at least one bore into the stem housing. A rotatable shaft is sealingly enclosed within the bore(s) and it protrudes into the flow passage. Another step entails affixing the valve plate to the shaft so that it will pivot between the opened and closed positions as the shaft is being rotated accordingly. |