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Technical Paper

Torsional Vibration Analysis of Six Speed MT Transmission and Driveline from Road to Lab

2017-06-05
2017-01-1845
When a manual transmission (MT) powertrain is subjected to high speeds and high torques, the vehicle driveshaft, and other components experience an increase in stored potential energy. When the engine and driveshaft are decoupled during an up or down shift, the potential energy is released causing clunk during the shift event. The customer desires a smooth shift thus reduction of clunk will improve experience and satisfaction. In this study, a six-speed MT, rear-wheel-drive (RWD) passenger vehicle was used to experimentally capture acoustic and vibration data during the clunk event. To replicate the in-situ results, additional data was collected and analyzed for powertrain component roll and pitch. A lumped parameter model of key powertrain components was created to replicate the clunk event and correlate with test data. The lumped parameter model was used to modify clutch tip-out parameters, which resulted in reduced prop shaft oscillations.
Technical Paper

Characterizing the Effect of Automotive Torque Converter Design Parameters on the Onset of Cavitation at Stall

2007-05-15
2007-01-2231
This paper details a study of the effects of multiple torque converter design and operating point parameters on the resistance of the converter to cavitation during vehicle launch. The onset of cavitation is determined by an identifiable change in the noise radiating from the converter during operation, when the collapse of cavitation bubbles becomes detectable by nearfield acoustical measurement instrumentation. An automated torque converter dynamometer test cell was developed to perform these studies, and special converter test fixturing is utilized to isolate the test unit from outside disturbances. A standard speed sweep test schedule is utilized, and an analytical technique for identifying the onset of cavitation from acoustical measurement is derived. Effects of torque converter diameter, torus dimensions, and pump and stator blade designs are determined.
Technical Paper

Methods of Pegging Cylinder Pressure to Maximize Data Quality

2019-04-02
2019-01-0721
Engine cylinder pressure measured with piezo-electric pressure transducers must be referenced or pegged to a known pressure at some point in the engine cycle. Traditionally, the pressure has been pegged to the pressure in the intake manifold plenum at Bottom Dead Center (BDC) at the end of the intake stroke. However, an error in pegging induces an error in the cylinder pressure trace, which has an adverse effect on the entire combustion analysis. This research is focused on assessing the pegging error for several pegging methods across a wide range of engine operating conditions, and ultimately determining best practices to minimize error in pegging and its propagation to calculated combustion metrics. The study was conducted through 1D simulations run in the commercially available GT-Power. The points studied included variations of speed, load, intake runner length and intake valve timing (including Late Intake Valve Closing (LIVC) and Early Intake Valve Closing (EIVC)).
Technical Paper

Control-Oriented Modeling of a Vehicle Drivetrain for Shuffle and Clunk Mitigation

2019-04-02
2019-01-0345
Flexibility and backlash of vehicle drivelines typically cause unwanted oscillations and noise, known as shuffle and clunk, during tip-in and tip-out events. Computationally efficient and accurate driveline models are necessary for the design and evaluation of torque shaping strategies to mitigate this shuffle and clunk. To accomplish these goals, this paper develops two control-oriented models, i.e., a full-order physics-based model and a reduced-order model, which capture the main dynamics that influence the shuffle and clunk phenomena. The full-order model comprises several components, including the engine as a torque generator, backlash elements as discontinuities, and propeller and axle shafts as compliant elements. This model is experimentally validated using the data collected from a Ford truck. The validation results indicate less than 1% error between the model and measured shuffle oscillation frequencies.
Technical Paper

Control Strategy and Energy Recovery Potential for P2 Parallel Hybrid Step Gear Automatic Transmissions

2019-04-02
2019-01-1302
The purpose of this investigation is to present a control strategy and energy recovery potential for P2 parallel hybrid step gear automatic transmissions. The automatic transmission types considered for the investigation are rear wheel drive a dual clutch transmission and a 10 speed planetary automatic equipped each equipped with a significant electric motor between the engine and transmission. The governing equations of clutch-to-clutch upshift controls are presented for each transmission type and various strategies are explored for executing the upshift under various input torque levels, shift times and engine torque management approaches. A lumped parameter dynamic model including the P2 electrification system is utilized for each transmission type to represent dynamic behavior representative of that expected in vehicle for achieving various levels of shift quality assessed with vibration dose value.
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