Technical condition evaluation of armored vehicle diesel engine based on deceleration process

The deceleration process of a diesel engine directly reflects its technical condition. This study combines simulation modeling with bench testing of armored vehicle diesel engines to establish a simulation model for the deceleration process under no-load conditions, systematically investigating the dynamic characteristics and influencing factors of this process. During bench testing, parameters such as cylinder pressure, vibration, and instantaneous speed were collected from eight diesel engines during deceleration from 800 r/min to 0 r/min. The characteristics of the deceleration curve were analyzed using third-order polynomial fitting. Based on simulation software, an optimization algorithm was employed to calibrate technical condition parameters (equivalent gas leakage diameter D and mechanical pressure loss coefficient f 1 ). Meanwhile, bench test data were used to validate the simulation model, ensuring that the average relative error between the simulated and experimental deceleration curves at each point remained within 5%. When studying the influence of technical condition parameters on the deceleration curve, it was found that, under the same condition of a 5% decrease in power during the no-load deceleration process, the impact of gas leakage was less significant than that of friction. Furthermore, threshold analysis of technical condition parameters revealed that when the equivalent gas leakage diameter ( D ) or the mechanical pressure loss coefficient ( f 1 ) reached extreme values, the absolute value of the primary coefficient ( k 1 ) of the deceleration curve increased significantly. Analysis and verification determined the evaluation parameter threshold to be 441. The research findings provide a theoretical basis and data support for the calibration of the diesel engine deceleration process and the assessment of its technical condition.