Engine intake manifold

Claim 1

An engine intake manifold comprising a riser the bottom wall of which is made of an electrically conductive material which is grounded and has an opening and an enlarged bore aligned with said opening, said opening and said enlarged bore defining therebetween a shoulder facing outwardly from the manifold, said enlarged bore being tapped; a threaded plug made of an electrically insulating material screwed into said enlarged bore, said plug having a depression to define a bank therearound and a hole in the bottom of said recess, said bank having at least one radial passage; a diaphragm made of a piezoelectric material fastened between said shoulder and said bank to confine gas flow through said opening, said diaphragm having a side which is opposed to an inlet of said riser and grounded through said shoulder; means for selectively applying a high frequency electric voltage to the both sides of said diaphragm, said means having a screw screwed into said hole, a terminal, and a spring retained between said screw and said terminal to urge said terminal against the opposite side of said diaphragm to establish an electric connection between said screw and said opposite side of said diaphragm, said screw confining a fluid flow through said hole, and said screw, said depression and said opposite side of said diaphragm defining a chamber, said means also having a high frequency electric oscillator circuited in series with said screw; an annular chamber formed in the bottom wall of said riser around said bank of said plug and fluidly communicating with said chamber through said radial passage; a damper liquid filling said chamber and said radial passage and occupying a portion of said annular chamber; and a pressurized gas filling the remaining portion of said annular chamber.