| 摘要 |
PURPOSE:To reduce time required for burning of sand core, by dividing a port liner along an axial plane of the same, forming a port core by way of welding or other method after pinching a preburnt sand core, and casting them into a unitary form. CONSTITUTION:Port liner 4 consists of linear portions 4a, 4b obtained by dividing the port liner 4 symmetrically in a place containing the axial center line of the liner 4. After port core 7 prefabricated by way of burning is placed between these liner portions 4a and 4b, their flange portions 8a, 8b are coupled together by way of welding or caulking. This port liner 4 is cast in exhaust port 3 which is connected to combustion chamber 2 formed in cylinder head 1, and heat-insulating space 6 is formed between port liner 4 and port wall 5. Since port core 7 can be pre-burnt as described above, time required for manufacturing the core can be shortened extremely, and at the same time, manufacturing of exhaust port is facilitated greatly. |
