Low-pressure EGR system without EGR valve and EGR exhaust gas flow control method thereof

The invention discloses a low-pressure EGR system without an EGR valve and an EGR exhaust gas flow control method, which are used for reducing the thermal load of an engine under a large-load working condition and reducing the risk of a knocking problem. The device comprises a supercharger, a Venturi tube, an air cylinder, an air inlet pipeline and an exhaust pipeline. The air inlet pipeline is connected with the air inlet end of the air cylinder. The first end of the exhaust pipeline is fixed to the exhaust end of the air cylinder, and the second end of the exhaust pipeline extends to be connected with the aftertreatment device. An air inlet turbine and an exhaust turbine are arranged in the supercharger, the air inlet turbine is communicated with an air inlet pipeline, and the exhaust turbine is communicated with an exhaust pipeline; an EGR system pipeline is arranged between the gas inlet pipeline and the gas exhaust pipeline, one end of the EGR system pipeline is connected to the front portion of the gas