Patent ID: 8298053

Claim:
A vent cap for venting an exhaust gas passage, comprising: i) a base, having a central opening for communicating with said exhaust gas passage, an outer perimeter, and a ramp surface extending between said outer perimeter and said central opening, said ramp surface sloping arcuately upwardly from said outer perimeter to said central opening and having a slope that increases with decreasing distance from the central opening, and a plurality of spaced, radially extending vanes projecting along and upwardly from said ramp surface and above said ramp surface to a distance which is a small fraction of less than the length of said ramp surface, but not projecting higher than an upper end of said ramp; ii) a top cover element supported above said base, the top cover element having a diameter greater than a diameter of said base, and the top cover element having a convex central upper surface, an annular thin outer edge portion extending around said convex central upper surface, and a convex central lower surface portion extending at its lowest point below a lowest part of said annular thin outer edge portion, and wherein said annular thin outer edge portion of said top cover element extends radially and has a radially outer portion that turns arcuately upwardly in an upwardly concave saucer-like, form to thereby in combination with said base cause a low pressure zone above said central opening in air moving horizontally through said vent cap; and iii) a plurality of slender legs supporting said top cover element above said base, each of said legs extending from said outer perimeter of said base to an outer margin of said annular thin outer edge portion.