Dynamic Analysis of Torque Converter Clutch Anti-Rattle Spring 2004-01-1226

In this paper we describe the development and application of a CAE methodology to investigate stresses incurred in the torque converter anti-rattle spring subjected to various static and dynamic loading conditions. The objectives of this study are three-fold. First, develop and demonstrate a dynamic modeling methodology suitable for torque converter rattle analysis. Second, provide insight into the underlying physics in the hardware design and identify key parameters to achieve high-mileage improvement, and third, recommend feasible design and manufacturing parameters for design improvements.

Anti-rattle springs have been widely used in torque converter clutch to reduce rattle noise between the spline interface of the cover plate and the piston plate. They are constantly subjected to static and dynamic stresses under various vehicle operation conditions. These stresses can be very significant and cause fatigue failure in springs if the parts involved are not properly designed and installed. The CAE dynamic stress analysis method is based on the commercial software ABAQUS in conjunction with engine vibration test data. The time history of engine vibration angular acceleration is converted to a sinusoidal function and is used as the dynamic input loading. The extreme of static and dynamic stresses and the corresponding locations are examined under various loading conditions for different designs. It is observed that high stresses occur at the locations around the nose area and the rivet corner, and the springs undergo periodic stress cycles under dynamic loadings. It is also noted that the cover plate installed loading positions play a significant role on the stress level. Thick spring (0.65mm) has shown higher stresses than that of thinner (0.55mm) spring under the same loading conditions. The analysis of the modified design has demonstrated a much-improved stress level and is recommended for design consideration.

In the demonstration of the dynamic analysis for the converter clutch system, we first describe the technical approach, followed by baseline evaluations. We then address the fundamental issues regarding critical design parameters and compare the results of the baseline design and the modified design. Finally, we discuss physics in the system and summarize the conclusions and recommendations of the work.