| As one of the most important components relative to passenger safety, the critical technology of Engine Control Unit (ECU) in automotive Engine Management System (EMS) is dominated by abroad well-known enterprise. With the booming development of domestic automotive industry, greatly stimulates self-development of ECU in Chinese automotive industry. The key factors of developing ECU are the design of mechanical components as well as system, hardware, software, calibration. Considering ECU had to work under the harsh environment of engine compartment for life time, it must fulfill to survive environmental stress such as high temperature, sine and broad band vibration, heat humidity, salt mist, corrosion, and so on. To guarantee the internal Printed Circuit Board (PCB) works properly and reliably, the adhesion sticking layer joint design of ECU is one of the chief aspects of mechanical component design so as to be the key to success in ECU project. Three methods application of theoretic analysis, simulation and test validation during development phases, ensures the reliability of ECU sealing function.In this paper, at first theoretical analysis method to be used to calculate stress and its distribution of adhesion joint with the simplified model under certain load according to the classic theory of shear lag and one-dimensional rod of rigidity imbalance. The founding is damage of bonding film of sealing structure stems from shear stress instead of peal stress. Great effort was made on researching factors which remarkably influenced on adhesive strength in terms of sealant thickness, bonding lap size and so on. Based on the conclusion, enlarging the lap width of adhesive film was regarded as feasible solution to improve sealing structure of ECU. With the improvement, new ECU boasts of meeting the need of design target which is smart, practical, small size, light weight. In the result, with condition of no enlarge product size, adhesive strength was enhanced.And then, simulation was performed by ABAQUS software on the sealing structure. By comparison of original, updated design, and result from theoretical calculation, the conclusion is effective by judgment on the failure of ECU. At the same time, test validation in reality was implemented to check and release design of sealing structure.In the end, the critical factors on components production and assembly process were presented in terms of cleaning, dispensing, curing, logistics, shelf life, etc which will have strikingly impact on adhesive strength to be studied and guaranteed the reliability in mass production. The plasma treatment as well as the optimized roughness of connector surface was implemented in mass production for the purpose of increase adhesive strength, which proved eligible by comparison.In addition, the founding of this paper could be beneficial and meaningful to any other automotive controller such as Transmission Control Unit (TCU), Body Control Module (BCM), oil pump controller which applies the same sealing structure or dispensing process. |
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