Assessment of Exhaust Actuator Control at Low Ambient Temperature Conditions

Exhaust sensors and actuators used in automotive applications are subjected to wide variety of operating ambient conditions , the performance of these actuators is challenging especially at cold ambient operating conditions, active exhaust tuning valves with position sensors are used to adjust the sound levels, or noise, vibration and harshness (NVH) from a control unit within the vehicle that leads to an improved driving experience wherein the driver selects their preferred sound levels. However, the operating behavior is crucially influenced by the characteristics of the drive cycle and ambient temperature. The study in this paper is intended to evaluate the icing formation at the start of drive cycle and at different ambient temperature conditions. The test data were obtained through real road and chassis dyno testing at different ambient conditions. The results of the testing indicated that a drive cycle with low engine speed and engine load, like a typical city road and cold ambient temperatures, had a low probability of successful operation of active exhaust valves. However, information reported from the actuator could be used along with other engine parameters to evaluate the performance of the system. In this study, an example of how the water collected in the exhaust system on gasoline only powertrain impacts the performance of the exhaust tuning valve is discussed. Root cause analysis is provided, noise factors of valve freezing is also evaluated, control software strategy is presented with vehicle validation results.