ENGINE INTAKE AND EXHAUST SYSTEM AND INTERNAL COMBUSTION ENGINE
FIG3 is a plan view of a part of an exhaust pipe to which an EGR cooler of the engine is coupled
As illustrated in FIG3, the curved pipe 13 constitutes a curve of the exhaust passage which changes a flow direction of the exhaust gas passed through the filter device 12, from the cylinder lined-up direction to a rear direction of the automobile. As illustrated in FIG3, the through-hole 18 communicating the internal space of the case of the EGR cooler 15 with the exhaust passage is formed into a long hole elongated in the flow direction of the exhaust gas in the curved pipe 13. Therefore, a portion of the exhaust gas, as the EGR gas, flows into the EGR cooler 15 at a relatively uniform flow rate, while spreading from the entire area of the long through-hole 18 in the flow direction of the exhaust gas, to flow through the heat exchanger. For this reason, compared to a simple circular through-hole having the same opening area, utilization efficiency of the EGR cooler 15 improves, which becomes advantageous for cooling the EGR gas. Further, since the filter 21 is provided in the through-hole 18, even if particulate matter, such as soot, within the exhaust gas flows thereto without being captured by the filter device 12 on the upstream side thereof, entrance of the soot, etc. into the EGR passage is blocked by the filter 21.
plan view
18
through-hole
14
flexible exhaust pipe
12
filter device
13
curved pipe
['1. An intake and exhaust system for an engine (1), comprising: an exhaust gas recirculation (EGR) passage (15, 16, 17) configured to recirculate a portion of exhaust gas as EGR gas, from an exhaust passage (2a, 11, 12, 13, 14) of the engine (1) to an intake passage (2b, 3, 4, 5, 8); and an EGR cooler (15) disposed in the EGR passage (15, 16, 17), the EGR cooler (15) being coupled to a passage wall of the exhaust passage (2a, 11, 12, 13, 14) at an EGR gas inlet side, and having a center line intersecting with a flow direction of exhaust gas in the exhaust passage (2a, 11, 12, 13, 14), wherein a through-hole (18) communicating the EGR cooler (15) with the exhaust passage (2a, 11, 12, 13, 14) is a long hole (18) elongated substantially in the flow direction in the exhaust passage (2a, 11, 12, 13, 14), wherein an exhaust gas purifier (12) is provided in an intermediate part of the exhaust passage (2a, 11, 12, 13, 14), wherein the exhaust gas passage (2a, 11, 12, 13, 14) has a curved pipe (13) on a downstream side of the exhaust gas purifier (12) in the flow direction to change the flow direction, wherein the through-hole (18) communicating the EGR cooler (15) with the exhaust passage (2a, 11, 12, 13, 14) opens to a passage wall of the curved pipe (13) of the exhaust passage (2a, 11, 12, 13, 14) at an outer circumferential side of the curve of the exhaust passage on an upper surface of the curved pipe (13), and the EGR cooler (15) is directly attached to the curved pipe (13).']