Abstract: The present disclosure provides a method for controlling EGR rate of a low pressure EGR system, a system and a vehicle. The method calculates a molar concentration of water molecules of exhaust gas processed by EGR cooler, calculates a molar concentration of water molecules, obtains coefficient as to excess air, and calculates a molar volume ratio of air according to the coefficient. Under a maximum limit of humidity, an allowable EGR rate of the exhaust gas processed by the EGR cooler is determined and an allowable EGR rate of the mixed gas before entry into supercharger and/or compressor is also determined, a lower EGR rate between the two allowable rates is set as a maximum for application actual working conditions. The present disclosure solves a problem of condensation caused by an introduction of exhaust gas from the existing gasoline engine.

Abstract: The present disclosure relates to a thermostat fault diagnosis method. The method includes: a current environment temperature and a boundary temperature and initial opening temperature corresponding to the current environment temperature are acquired; engine thermal equilibrium state data determined based on coolant temperature change data in an engine are acquired; a current coolant temperature is acquired; and according to the engine thermal equilibrium state data and a relationship between the current coolant temperature and the boundary temperature and initial opening temperature, it is judged whether a thermostat is faulty.

Abstract: The present disclosure relates to a thermostat fault diagnosis method. The method includes: a current environment temperature and a boundary temperature and initial opening temperature corresponding to the current environment temperature are acquired; engine thermal equilibrium state data determined based on coolant temperature change data in an engine are acquired; a current coolant temperature is acquired; and according to the engine thermal equilibrium state data and a relationship between the current coolant temperature and the boundary temperature and initial opening temperature, it is judged whether a thermostat is faulty.

Abstract: A method for calculating Atkinson cycle intake flowrate of an internal combustion engine includes determining an intake stopping point and an engine crank angle corresponding to a piston position of the internal combustion engine at the intake stopping point; calculating mass and partial pressure of an exhaust gas and a fresh gas within a cylinder from the engine crank angle; obtaining a mass ratio of a quantity of gas pushed out of the cylinder by a piston to a total quantity of gas within the cylinder at the intake stopping point during a period of time starting from the intake stopping point until intake valve closure; and calculating intake flowrate of the fresh gas within the cylinder at the intake valve closure from the mass ratio obtained. Also disclosed is a system for calculating Atkinson cycle intake flowrate of an internal combustion engine.

Abstract: A method for calculating Atkinson cycle intake flowrate of an internal combustion engine includes determining an intake stopping point and an engine crank angle corresponding to a piston position of the internal combustion engine at the intake stopping point; calculating mass and partial pressure of an exhaust gas and a fresh gas within a cylinder from the engine crank angle; obtaining a mass ratio of a quantity of gas pushed out of the cylinder by a piston to a total quantity of gas within the cylinder at the intake stopping point during a period of time starting from the intake stopping point until intake valve closure; and calculating intake flowrate of the fresh gas within the cylinder at the intake valve closure from the mass ratio obtained. Also disclosed is a system for calculating Atkinson cycle intake flowrate of an internal combustion engine.