Wideband Oxygen Sensor Research Articles

Adaptive system on engine misfire and knocking features for IC engine

Most countries in the world still rely on internal combustion engines as their daily means of transportation. The issue with internal combustion engines is irregularities in the combustion process that impact the environment, including misfiring and knocking. Numerous engineers and researchers have conducted studies to find solutions to this important engine problem to improve engine efficiency and achieve quality characteristics and customer satisfaction. The research aims to identify a workable integrated solution for the misfire and knocking features of an internal combustion engine. The RedLeo Pro V8 version 8.033 software was used to simulate the input data monitoring and control engine system. The engine condition was controlled by the Engine Control Unit (ECU). Data was collected using a vibration sensor and a wideband oxygen sensor. Low Processing program was used to represent data in two or three-dimensional graphs to determine the decision method. These signals were synthesized as adaptive system design signals to reduce noise and improve accuracy, enabling modification between normal and abnormal signals. As a result, the proposed method proves to be an effective method for engine fault diagnosis performed on the methodological paradigm of feature extraction and feature selection.

Design and experimental validation of three way catalyst age estimator and Fisher information analysis for optimal sensor selection

Three way catalysts (TWCs) are installed downstream of internal combustion engines to mitigate the engine out pollutants generated from combustion. Accurate engine control systems are needed to achieve high conversion efficiency during vehicle operation and optimize TWC inputs. Accounting for TWC internal dynamics within the exhaust emission control design is key to enable improved engine and catalyst performance.However, since internal TWC dynamics cannot be directly measured, modeling and estimation of the converter’s dynamics are essential for the development of high performing exhaust emission control strategies. In this paper, a Dual Extended Kalman Filter (dEKF) is designed and experimentally validated for the estimation of both the TWC oxygen storage level, ϕ, and age-dependent oxygen storage capacity, OSC. The estimator design is based on an experimentally validated physics-based TWC model developed by the authors in a previous work. Observer validation and performance evaluation are conducted over transient drive cycles in a chassis dynamometer. Moreover, observability properties and related estimation performance are analyzed using different sensor technologies. It is found out that using switch-type oxygen sensors in place of wideband oxygen sensors leads to a loss of observability within the model, preventing real-time OSC determination and, therefore, aging estimation. A Fisher information quantity study is developed and presented that provides quantitative guidelines for the optimization of TWC sensor design. Finally, the observer is tested on real hardware via rapid control prototyping.

Comparison of performance using wide-band versus narrow-band oxygen sensors in gasoline engines

Spark ignition engines are the most widespread in the automotive industry, they consume more than 35% of the liquid fuel. Therefore, it is of a great value to reduce this percentage the minimum possible. Using electronics and direct injection with the wide-band oxygen sensor may be the technology to solve this problem since traditional electronic control systems use reference stoichiometry to regulate air fuel ratios, using the wide-band oxygen sensor permits the use of reference air fuel ratio values over a wider range.Experiments were carried out on a 4-cylinder 1.8 L displacement volume Mitsubishi 4G93 DOHC GDI using the narrow-band lambda oxygen sensor and the wide-band lambda oxygen sensor, utilizing a lean air-fuel ratio. Road load test conditions were considered. A dynamometer was used in addition to a scan tool and an exhaust gas analyzer. Development extensive work was carried out to correct the single-band to wide-band.The obtained results show that using the wide-band oxygen sensor improves brake specific fuel consumption by 8.8–11.6% between 25% and 100% throttle openings. Whereas, HC and NOx emission gases were reduced by 19.4% and 27.3%, respectively.

In-Cylinder CO2 Sampling Using Skip-Firing Method

Skip-firing (or cylinder de-activation) was assessed as a method of sampling CO2 directly in the cylinder at higher speeds than previously possible. CO2 was directly sampled from one cylinder of a 1 L three-cylinder gasoline engine to determine the residual gas fraction (RGF) using a fast response CO/CO2 analyzer. Acquisition of data for similar measurements is typically limited to engine speeds of below 1300 revolutions per minute (rpm) to allow full resolution of the sample through the analyzer that has an 8 ms finite response time. In order to sample in-cylinder CO2 at higher engine speeds, a skip-firing method is developed. By shutting off ignition intermittently during engine operation, the residual CO2 from the last firing cycle can be measured at significantly higher engine speeds. Comparison of RGF CO2 at low speeds for normal and skip-fire operation shows good correlation. This suggests that skip-firing is a suitable method for directly measuring internal exhaust gas recirculation up to at least 3000 rpm. The measurements obtained may provide a useful tool for validating internal exhaust gas recirculation models and could be used to calculate combustion air–fuel ratio from the CO and CO2 content of the burned gas. These are typically complicated parameters to predict due to the slow response time and sensitivity to hydrocarbons of wide-band oxygen sensors. A differing pattern of RGF change with increasing speed was seen between normal and skip-fire operation.

The influence of exhaust system leak on the operating parameters of a turbocharged spark ignition engine

Turbocharging of an internal combustion engine is the most common technique to improve an engines’ performance. In present it is not hard to meet vehicles on the road with turbocharged SI engines, which have a high mileage, and because of this fact there is a high risk of exhaust systems leak. This might have its influence not only on the emissions, but also on the vehicles performance. Thereby this dissertation shows the comparative analysis of the influence of exhaust system leak in the catalyzer input on the exhaust gasses composition in the catalyzer output and the operation parameters of an turbocharged SI engine. During the research some parameters were recorded and compared, e. g.: the engines power and torque, the injec-tors opening time, the oxygen sensors voltage signals in the input and in the output of the catalyzer, the concentration of harmful gasses in the exhaust tailpipe. The research was conducted with the use of a single roller MAHA MSR 500 chassis dynamometer. A series of torque measurements was performed. Under these measurements a simulation of the exhaust system leakage of a turbocharged SI passenger car engine was made. As a result three variations of the wideband oxygen sensor acting were reached. The wideband sensor is mounted between the turbocharger unit and the input of the catalyzer. In the test the influence of the leakage on the injector’s opening time and the composition of harmful exhaust substances were pointed.

Operating parameters of a passenger vehicle turbocharged spark ignition engine in conditions of exhaust leakage simulation

Paper discussed the influence of exhaust system leakage on the utility parameters and toxic combustion products emission of a turbocharged passenger car spark ignition engine. A comparative analysis of the data gathered in the research carried out using the MAHA MSR 500 single roller chassis dynamometer was conducted, where the exhaust system was sealed and leaking in the area of the wideband oxygen sensor mounting bracket. The presented data refers to among others: the emissions of harmful gasoline oxidation products (HC, CO), the courses of power generated by the engine and the momentary values of excess air ratio. The EUDC driving cycle was used in the research.

Effect of Exhaust Gas Recirculation on Biodiesel Blend Level Estimation in Diesel Engines

Biodiesel is an alternative fuel derived from vegetable oils, animal fats, or other sources, and it can be made into biodiesel blends by mixing with conventional diesel. To achieve optimal engine combustion as well as minimal emissions with biodiesel blends, on-board blend level estimation system is one of the prerequisites. The paper investigates a blend level estimation system by evaluating exhaust oxygen fraction differences between diesel and biodiesel. In the system, a wideband oxygen sensor is utilized to measure the oxygen concentration. Then, research on the oxygen-content based biodiesel blend level estimation system is extended by taking the exhaust gas recirculation (EGR) into account. Since estimation accuracy under the lean conditions for this kind of system has been especially problematic, the effect of EGR on system estimation uncertainty is discussed. The theoretical formulation shows that oxygen consumption factor is an intrinsic indicator of fuels, which is not affected by the EGR level. However, the “shifting effect” caused by introducing EGR can help moving the estimation points into a range where not only the oxygen sensor but also the whole estimation system exhibits lower measurement uncertainty. Validations are provided by both simulation results based on a high-fidelity GT-Power engine model and experimental results on a medium-duty turbo-charged diesel engine platform.

Steady-State Biodiesel Blend Estimation via a Wideband Oxygen Sensor

A substantial opportunity exists to reduce carbon dioxide (CO2) emissions, as well as dependence on foreign oil, by developing strategies to cleanly and efficiently use biodiesel, a renewable domestically available alternative diesel fuel. However, biodiesel utilization presents several challenges, including decreased fuel energy density and increased emissions of smog-generating nitrogen oxides (NOx). These negative aspects can likely be mitigated via closed-loop combustion control provided the properties of the fuel blend can be estimated accurately, on-vehicle, in real-time. To this end, this paper presents a method to practically estimate the biodiesel content of fuel being used in a diesel engine during steady-state operation. The simple generalizable physically motivated estimation strategy presented utilizes information from a wideband oxygen sensor in the engine’s exhaust stream, coupled with knowledge of the air-fuel ratio, to estimate the biodiesel content of the fuel. Experimental validation was performed on a 2007 Cummins 6.7 l ISB series engine. Four fuel blends (0%, 20%, 50%, and 100% biodiesel) were tested at a wide variety of torque-speed conditions. The estimation strategy correctly estimated the biodiesel content of the four fuel blends to within 4.2% of the true biodiesel content. Blends of 0%, 20%, 50%, and 100% were estimated to be 2.5%, 17.1%, 54.2%, and 96.8%, respectively. The results indicate that the estimation strategy presented is capable of accurately estimating the biodiesel content in a diesel engine during steady-state engine operation. This method offers a practical alternative to in-the-fuel type sensors because wideband oxygen sensors are already in widespread production and are in place on some modern diesel vehicles today.

A transient virtual-AFR sensor using the in-cylinder ion current signal

This paper presents a neural network (NN) based air-to-fuel ratio (AFR) estimation scheme for spark ionization sensors in gasoline internal combustion (IC) engines. The proposed hardware and software estimation system results in a virtual wideband oxygen sensor for an individual cylinder. Principal component analysis (PCA) of the spark ionization signal is used with manifold absolute air pressure (MAP), fuel pulse width (FPW) and engine speed to train a NN offline to predict the AFR under transient engine load and speed settings. Experimental results from dynamometer tests on a port fuel-injected (PFI) four cylinder 1.6 l gasoline IC engine demonstrate that the NN based AFR prediction correlates well with AFR measured from a universal exhaust gas oxygen (UEGO) λ -sensor mounted in the exhaust manifold. The prediction is experimentally demonstrated to be robust to transients of load and engine speed. The experimental results significantly advance those of the previously published studies which have been largely restricted to simulation.

Solid‐State Electrochemical Gas Sensors

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