| 摘要 |
1491883 Cylinder intake systems YAMAHA HATSUDOKI KK 14 Oct 1974 [24 May 1974 26 June 1974 12 Aug 1974] 44383/74 Heading F1B In a four-stroke I.C. engine having respective inlet and exhaust ducts and valves for each cylinder, a separate mechanism, e.g. a carburetter or injector, with a throttle valve for introducing air/fuel mixture into each inlet duct and passage means inter-connecting the inlet ducts, means are provided for restricting flow between the inlet ducts via the passage means. The restricting means prevent the different pressures existing in the inlet ducts during engine operation at low loads from having a detrimental effect on the pressure in the inlet duct whose inlet valve is open and the cylinder piston is completing its exhaust stroke. Thus scavenging of the associated cylinder is improved, whereby the engines will operate on leaner mixtures at low loads to reduce the quantity of pollutants in the exhaust gases. In the Fig. 3 embodiment an exhaust gas recirculation system is incorporated in a four cylinder engine. Gas is tapped at 44 from an exhaust reactor 40 and is supplied to the four inlet ducts via cooler 45, control valve 46, recirculation valve V and respective pipes 13a-d. The valve V provides the restricting means of the invention and functions to close during low loads to isolate the pipes in response to the suction in one of the inlet ducts, the suction being communicated to valve-actuating diaphragm-chamber 205 via a line 12e. Similarly, the control valve 46 is controlled by the suction communicated through line 12e. In another embodiment where the gas recirculation system is omitted but the inlet ducts are nevertheless interconnected by passage means, the latter are provided with a number of restricted orifices (209), Fig. 4 (not shown), which function as the restricting means. |
