Abstract: An exhaust gas recirculation system includes a first turbocharger and a second turbocharger connected in series. An outlet of a turbine of the second turbocharger is connected to an exhaust pipe. An inlet of a compressor of the second turbocharger is connected to the exhaust pipe by means of an EGR gas collection pipe, and an outlet of the compressor of the second turbocharger is connected to an intake manifold by means of a low-pressure EGR exhaust pipe. The system employs energy of exhaust gas to drive turbines of a two-stage turbocharging system, thereby increasing utilization of the exhaust gas and improving the economic efficiency of an engine. An engine is also disclosed.

Abstract: An engine exhaust aftertreatment device includes a first exhaust treatment unit and/or a second exhaust treatment unit; the first exhaust treatment unit includes a first bypass pipeline and a first connection pipe provided between a DPF and an SCR; the second exhaust treatment unit comprises a second bypass pipeline and a second connection pipeline provided between a DOC and the DPF, one end of the second bypass pipeline being in communication with the turbine front exhaust pipe, and the other end of the second bypass pipeline being in communication with the second connection pipeline; when it is detected that an engine satisfies a starting condition of the first exhaust treatment unit, the first exhaust treatment unit starts; and when it is detected that the engine satisfies a starting condition of the second exhaust treatment unit, the second exhaust treatment unit starts.

Abstract: An exhaust gas recirculation (EGR) system comprises a first turbocharger (7) and a second turbocharger (6) connected in series. An outlet of a turbine (601) of the second turbocharger is connected to an exhaust pipe (9). An inlet of a compressor (602) of the second turbocharger is connected to the exhaust pipe by means of an EGR gas collection pipe (4), and an outlet of the compressor (602) of the second turbocharger is connected to an intake manifold (2) by means of a low-pressure EGR exhaust pipe (5). The system employs energy of exhaust gas to drive turbines of a two-stage turbocharging system, thereby increasing utilization of the exhaust gas and improving the economic efficiency of an engine. An engine is also disclosed.

Abstract: An engine exhaust aftertreatment device, comprising a first exhaust treatment unit and/or a second exhaust treatment unit; the first exhaust treatment unit comprises a first bypass pipeline (1) and a first connection pipe (4) provided between a DPF (2) and an SCR (3), one end of the first bypass pipeline (1) being in communication with a turbine front exhaust pipe (9), and the other end of the first bypass pipeline being in communication with the first connection pipe (4); the second exhaust treatment unit comprises a second bypass pipeline (19) and a second connection pipeline (20) provided between a DOC (13) and the DPF (2), one end of the second bypass pipeline (19) being in communication with the turbine front exhaust pipe (9), and the other end of the second bypass pipeline being in communication with the second connection pipeline (20); when it is detected that an engine (11) satisfies a starting condition of the first exhaust treatment unit, the first exhaust treatment unit starts; and when it is detec