Idle air control

Claim 1

In an internal combustion engine having an induction passage for air flow to the engine and a throttle in said induction passage movable between open and closed positions for controlling air flow therethrough: means for controlling air flow into said induction passage downstream of said throttle, said means comprising an enclosed housing defining a chamber, said housing having an inlet opening to permit air flow into said chamber, said housing including a planar wall having an outlet opening connected with said induction passage downstream of said throttle; a slide valve overlying said wall and having a contoured port therethrough cooperating with said outlet opening to vary the effective area thereof and thereby control air flow through said outlet opening from said chamber to said induction passage; spring means biasing said slide valve against said housing wall to prevent air leakage therebetween; and means for positioning said slide valve including a power element having a cup secured in said housing, a mass of thermally expansible material disposed in said cup, a seal enclosing said material in said cup, and a plunger received by said seal and displaceable axially from said cup upon thermal expansion of said material; a cupped receptacle receiving said power element cup, said receptacle including heating means for converting the electrical energy of current flow into heat energy; means for passing an electric current through said heating means; spring means biasing said receptacle into thermal contact with said power element cup whereby said power element will be heated by said heating means and said plunger will be displaced from said cup; a link connecting said power element plunger and said slide valve to move said slide valve as said power element is heated and thereby reduce the effective area of said outlet opening, the length of said link being adjustable for adjusting the initial position of said slide valve relative to said power element plunger; and spring means biasing said slide valve to move said slide valve as said power element cools and thereby increase the effective area of said outlet opening.