In order to control the engine performance which is driven by the strict emission regulations and customer request for the improved fuel economy, precise air intake measurement and fuel control system are essential. In the modern engines, the mass air flow sensor (MAF) acts an important role which provides a precise estimation of air flow from the clean side ducting of air intake system to engine control unit module (ECU). The hot wire mass air flow sensor are mounted on the clean side of the air intake system in order to protect the sensing element from the contamination and to extend their lifespan as well as maintain its accuracy. It is essential to maintain a steady and a uniform airflow at the sensing element of the MAF sensor for reliable sensor reading at different engine speeds and varying engine load. However, the physical limitations of engine packaging inside the engine bay, limits the sensor placement. Incorrect sensor mounting can lead to errors in the airflow estimation which in turn adversely affect engine thermal performance and emissions.
During the development of a new passenger vehicle, it was observed that the unpredicted engine torque oscillations were detected and that too in various operating conditions. When the root cause of these oscillation were studied, it was linked with the oscillations and fluctuations in the MAF sensor’s output signal. In order to address the issue, a number of clean side ducting as well as air filter assembly top cap geometry and configuration were modified and studied. These design iterations were tested on the dynamometer in order to identify their effect on the sensor signal and corresponding engine torque variation.
The current paper presents the investigation and evaluation of the different clean side ducts geometries and sensor mounting strategies. This would ensure that there will be minimum signal disturbance which would further improve the mass air flow measurement accuracy. The final air intake clean side design have reduced sensor signal pulsations and oscillations significantly. This has further lead to a smoother and more stable engine torque output.