Auto throttle and exhaust flow control module construction

An exhaust gas throttle unit for an internal combustion engine, said unit comprising a tubular wall of a section of exhaust pipe section of an internal combustion engine,

• said tubular wall having an inner cylindrical surface of uniform diameter having open ends and an exhaust gas flow passage extending therethrough along a longitudinal axis of said inner cylindrical surface,
• a gate plate access opening is formed through said tubular wall and opens into said flow passage, a housing wall structure extends outwardly from said tubular wall and overlies said access opening and is formed to provide a sealed pocket cavity on an exterior portion of said tubular wall, which pocket cavity comprises a pivot section and a gate plate stop recess (102) having a stop ceiling (116),
• a gate plate having a concave side and a convex side is provided having a width component (“W”), a functional plane, an apex surface and a thickness dimension,
• a gate plate pivot shaft is rotationally mounted in said pivot section and having a rotation axis positioned exteriorly of said exhaust gas flow passage and being oriented normal to said longitudinal axis of said pipe section, a torsion spring having first and second ends, said first end being affixed to said pivot section housing and said second end being affixed to said pivot shaft, said torsion spring being operable to resist pivoting of said pivot shaft and opening of said gate plate toward said pipe section tubular wall to an increasing degree as exhaust gas pressure forces (“PF”) against said width component (“W”) of said gate plate increase, said gate plate having a longitudinal axis (32A) and a lateral axis (32B), and further having a connection neck portion extending outwardly from a peripheral edge portion of said gate plate generally along said longitudinal axis of said gate plate and extending through said access opening, said neck portion being affixed to said pivot shaft at a connection point on said pivot shaft which is laterally offset an eccentric measure (109) from said rotation axis of said pivot shaft, said connection point of said gate plate to said pivot shaft orients said width (“W”) component of said gate plate normal to gas flow pressure forces (“PF”) against said gate plate width component (“W”) whereby said component (“W”) is also laterally offset by said eccentric measure from said pivot shaft rotation axis, and wherein said eccentric measure is substantially the same as the measure from said stop ceiling of said stop recess to said pivot shaft rotation axis, whereby said convex side of said gate plate will lie adjacent to said stop ceiling when said gate plate is in its full open position.