IDLE CONTROLLER

PURPOSE:To improve control accuracy and reduce the initial leak by connecting a bypass passage having a compensating valve which cooperates with a metering valve to an intake air passage, thus preventing the influence of the differential pressure. CONSTITUTION:A metering part consists of a seat 23 and a valve 25, and a negative-pressure compensating mechanism 31 consists of a sleeve 29 and a compensating valve 30. The clearance 32 between the sleeve 29 and the compensating valve 30 only permits the introduction of pressure and does not permit the flow of air. When a negative-pressure P1 is applied into the following wake of the valve 25, the same negative-pressure P1 is applied also onto the compensating valve 30, and the static-pressure forces F1 and F2 applied onto the valve 25 and the compensating valve 30 become the values obtained by multiplying the negative-pressure P1 by the areas S1 and S2 of the valves, and when F1 becomes equal to F2, the stroke of the valve 25 is not influenced by the magnitude of the negative-pressure, and the flow rate is not influenced by the negative pressure.