AIR-INTAKE APPARATUS FOR ENGINE

PURPOSE:To moderate shocks caused at the time of switching use of oxygen- enriched air and ordinary air supplied to a combustion chamber according to the operational conditions of an engine, by providing a control means for controlling switching of air to be use so that the switching speed is made slow, in an air intake apparatus for engine comprising an oxygen enriching means. CONSTITUTION:An oxygen enriching means 23 increases the rate of oxygen contained in air by passing much oxygen through an oxygen-permeable membrane 15 by the function of pressure difference on the opposite sides of the membrane 15 that is produced through operation of a feed pump 16 and a suction pump 17. The oxygen-enriched air thus obtained is supplied to a combustion chamber 1a via a supply passage 13 when an oxygen-density control valve 18 is opened and a relief valve 22 is closed. In such an arrangement, switching of the oxygen- enriched air and ordinary air supplied from a main intake passage 2 is achieved by controlling the control valve 18 and the relief valve 22 by means of a control circuit 8. Here, the switching speed is controlled to be slow by an operation control means consisting of an integration circuit, etc. in the control circuit 8.