Online calculation method for flow coefficient of nozzle of oil injector based on inlet pressure wave of oil injector

The invention discloses an oil injector nozzle flow coefficient online calculation method based on oil injector inlet pressure waves. Installing a pressure sensor on a high-pressure oil pipe of the oil injector and collecting inlet pressure of the oil injector; obtaining a pressure change rate curve of the inlet pressure; obtaining a second derivative curve of the inlet pressure; combining the feature points on the pressure change rate curve with the second derivative to judge the feature moments when the W1, the W2 and the W3 reach the measurement points; judging whether the W3 reaches a pressure measuring point or not according to the obtained feature points on the second derivative curve, and decoupling the W1 to obtain a flow coefficient if the W3 does not reach the pressure measuring point; and if a pressure test point is reached, the W1 and the W3 are decoupled to obtain a flow coefficient. The invention aims to solve the problems of high cost, insufficient model precision and the like when the existing