Multiple-bore throttle valve having central shaft end-play restraint

Abstract

A multiple-bore throttle valve wherein the valve shaft is restrained from end play at a point between two of the flow bores. A passageway in the valve body between the flow bores intersects the valve shaft bore non-diametrically. The valve shaft has a circumferential groove at the point of intersection. A pin pressed into both the passageway and the groove axially restrains the shaft at that location. Since thermal expansion or contraction of the shaft in its axial direction can proceed only from the point of restraint, a dual-bore valve in accordance with the invention exhibits length changes in each bore equivalent to that of a single bore valve, which is less than half the shaft length change exhibited in at least one bore of a prior art dual-bore throttle valve. Similarly, a triple-bore valve exhibits expansion comparable to individual prior art single-bore and dual-bore valves, and a quadruple-bore valve exhibits expansion comparable to a prior art dual-bore valve.