| 摘要 |
PURPOSE:To efficiently purify and discharge CO, HC, etc., by providing a port liner in an exhaust port to make a heat insulating layer on the inside surface and keep the temperature of the exhaust gas in the exhaust port high. CONSTITUTION:An exhaust port shell 4 is provided around the port liner 1 made of heat-resisting metal. An inflammable substance 5 is filled in an opening surrounded by the shell 4 and the port liner 1, thereby making an exhaust port core 6. When the cylinder head is cast, the exhaust port core 6 is set on the wall 8 of the exhaust port 9 of the cylinder. Thereby, the core 6 is molded together with the cylinder 7. The exhaust ports 9 of the adjacent cylinders are connected to each other in the cylinder head. Therefore, when the exhaust gas is discharged to the exhaust port 9, the exhaust gas is affected by the temperature of the exhaust port of the adjacent cylinder. As a result, the exhaust gas is maintained at a high temperature. |
