| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust air recirculation device of a cylinder head, which can be increased in surface area for heat transfer to improve the cooling efficiency of EGR gas, and can secure the sealing property of EGR gas and cooling water and the rigidity of an EGR passage while easily disposing the EGR passage in the cylinder head by casting.SOLUTION: A flat heat transfer pipe 40 for heat exchanger includes an exhaust gas inflow end portion 41 communicating with the other end of an EGR pipe 31, and an exhaust gas outflow end portion 42 communicating with an EGR valve 32. Each of the exhaust gas inflow end portion 41 and the exhaust gas outflow end portion 42 is formed circularly in a cross section by a plane vartical to a circulating direction of exhaust gas. The flat heat transfer pipe 40 is dispoed within a water jacket 15 of the cylinder head 11 by casting the exhaust gas inflow end portion 41 and the exhaust gas outflow end portion 42 respectively to the exhaust side and intake side of the cylinder head 11. |
