Research Of Engine Rotational Inertial Parameter Test Based On Three Force Excitation

How to reduce and isolate engine vibration is an important issue in vehicle development. Reducing the vibration transmission can reduce the body parts fatigue damage and improve the seating comfort. Optimal design of suspension system can effectively reduce the reciprocating vibration of engine and isolate the vibration transmission, and reduce the internal vibration and noise accordingly. The inertial parameter of the engine is an important input during the optimization design of suspension system. It is the precondition of engine vibration analysis.In order to get the engine inertial parameter precisely, the identification methods of engine inertial parameters are studied systematically. According to the shortcomings of the traditional mass line method, an engine inertial parameter identification method based on the three-axis force excitation and six-axis acceleration response is proposed. The new method excites the rigid body from different angles repeatedly and get the three-axis force value in the excitation point and six-axis acceleration value in response point. By substituting the force value and acceleration value into the inertial parameter identification program, the ten inertial parameters of the rigid body are solved.The method requires at least two excitation points, one response point and three different excitation directions. The causes of identification error is analyzed. In order to control the identification parameter’s relative error within 5% except for the product of inertia, four types measurement error of length and angle should be controlled within the following ranges: 1) the error of excitation point coordinate should be less than 15mm; 2) the error of response point coordinate should be less than 5mm; 3) the installation angle error of six-axis acceleration sensor should be less than 2 degree; 4) the mounted angle error of three force sensor should be less than 2 degree. Increasing the number of excitation angle and response points can effectively reduce the impact of these errors on the identification accuracy.The validity of the proposed algorithm are verified by the simulating model and standard block which mass and center of mass is the same with engine. The identification results are compared with that of mass line method and theoretical values, the results further demonstrate the effectiveness of the algorithm.This new method does not require special test bench and its theory is simple. It can be applied to all rigid body inertial identification, especially complex shape rigid body. It has great engineering application value.