Combustion monitoring in engines using accelerometer signals (original) (raw)
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Remote Combustion Sensing in Diesel Engine via Vibration Measurements
Improvement Trends for Internal Combustion Engines, 2018
An efficient control of the combustion process is required in order to comply with regulations on pollutant emissions from internal combustion engines. Literature presents investigations devoted to explore the potentiality of externally mounted sensor (speed sensor, microphone, and accelerometer) for combustion diagnosis. A relationship exists between the combustion event measured via an in-cylinder pressure transducer and engine block vibration measured via an accelerometer. Time and frequency domain processing of acquired signals highlighted the correlation between parameters able to characterize the combustion development and features derived from the engine block vibration data. A methodology was developed by the authors that demonstrated to be suitable for real-time estimation of combustion progress based on engine vibration. A two-cylinder common rail diesel engine of small displacement was tested; two configurations were investigated, naturally aspirated, and turbocharged. The in-cylinder pressure and block vibration signals were acquired and processed in time and frequency domains. The vibrational components mainly related to the combustion process were extracted, and indicators of the combustion positioning were computed. The angular positions of start of combustion (SOC) and MFB50 computed via the heat release curve by means of the in-cylinder pressure measurements were compared to those obtained by means of the accelerometer signal. High correlation coefficients were obtained for the data acquired during the testing of both naturally aspirated and turbocharged configurations in the complete engine operative field.
Accelerometer Based Methodology for Combustion Parameters Estimation
Energy Procedia, 2015
Due to increasingly stringent emission regulations and the need of more efficient powertrains, obtaining information about combustion process becomes a key factor. Low-cost in-cylinder pressure sensors are being developed, but they still present longterm reliability issues, and represent a considerable part of the engine management system cost. Research is being conducted in order to develop methodologies for extracting relevant combustion information using standard sensors already installed on-board. The present work introduces a methodology for combustion parameters estimation, through a control-oriented analysis of structureborne sound. The paper also shows experimental results obtained applying the estimation methodology to different passenger car engines.
Analysis of Vibration on an Engine Block Caused by Combustion in a Diesel Engine
International Journal of Automotive Technology, 2019
An accelerometer replaced an in-cylinder pressure sensor to detect the combustion status. The correlation between the vibration on an engine block caused by direct combustion as well as the combustion status was analyzed. The direct combustion vibration was determined. The direct combustion vibration on an engine block was blended with indirect combustion vibrations and other accessories. In addition, the combustion status was specified among several combustion status parameters, namely, RoHR, MPRR, and the peak pressure. There were two distinct vibrations in the motoring state. The frequency range of 2.5−8 kHz and 0−10 o CA aTDC was assumed to be a crankshaft vibration. The other vibration, 1−3 kHz and 20−30 o CA aTDC, was estimated as a slap motion of the piston. The combustion vibration frequency was 0.1−8 kHz after combustion. As an injector vibration (3−8 kHz) disrupted the search for combustion noise, a 0.1−2 kHz vibration range was appropriate for finding the correlation with the direct combustion state and the peak of the RoHR. As the peak of the RoHR was proportional to the combustion noise, the estimated peak of the RoHR can be used to control the diesel engine's combustion noise. Estimation was possible in the transient and steady states.
Accelerometer measurement for MFB evaluation in multi-cylinder diesel engine
Energy, 2017
Indirect methods have great potential for engine diagnosis. Several methodologies have been proposed in the past in which indirect measurements are used for combustion sensing. This paper presents the results of the application of a methodology developed by the authors in which an accelerometer mounted on the engine block is used to characterize the combustion development in a multi-cylinder common rail diesel engine. The high correlation between accelerometer and in-cylinder pressure data allowed to use the vibration signals to evaluate the angular positions where: the combustion starts, 50% of fuel is burned over an engine cycle (MFB50) and the combustion process ends (MFB95) in two of the engine cylinders. The great accuracy of the predictions (the square value of the correlation coefficient was always higher than 0,97) demonstrated that a single accelerometer can be used in control algorithms for the optimal positioning of the combustion process in more than one cylinder.
2008 47th IEEE Conference on Decision and Control, 2008
This paper proposes a method to estimate and to control the combustion timing of a Diesel Homogeneous Charge Compression Ignition (HCCI) engine without cylinder pressure transducers. The principle of the proposed controller is to correct the start of injection (SoI) in order to compensate the effects of the air path errors or injection system perturbation. The controller takes as inputs the middle of combustion estimated from the vibration trace recorded with a knock sensor fitted at the surface of the engine block. The estimated combustion parameters are computed in real-time and sent to the engine control system in a cycle to cycle manner. The contribution of this paper is combustion state estimator and controller that allows to maintain the desired combustion timings. Tests are performed on a test bench to compare the estimated and measured combustion timing. The closed-loop controller is validated in steady engine conditions and the obtained results demonstrate the potential of this approach.
Journal of Vibroengineering, 2016
An estimation method of the combustion chamber pressure, in an internal combustion engine, based on the processing of the vibration (acceleration) signal of the cylinder head, at constant speed and no load conditions is presented in this paper. The model is created based on the comparison of the vibration and pressure signals around the peaks of highest vibration, after a preprocessing and filtering of the signal using the most similar frequency bands between the sources. A polynomial regression is used between the selected data points to generate the resulting model relating pressure and vibration (and average rotational speed per cycle, calculated based on the vibration peaks). The model is tested with measurements from two spark ignited engine test benches: a single cylinder engine and a four-cylinder engine. The resulting model has very low computational cost and can provide a very accurate estimation of general shape and magnitude of the pressure trace, but does not reflect strongly cycle by cycle variations. Testing the Normalized Root Mean Square Error (NRMSE), where the best value is 100 % the single cylinder engine scores were 63.52 % and 20.02 % for the points before and after the vibration peak. For the four-cylinder engine those values were: 82.47 % and 28.27 % respectively.
— In addition to the performance evaluation of the IDI engine with alternate fuel like waste cooking oil biodiesel, an attempt was made to evaluate the engine performance indirectly by measuring engine cylinder vibrations. The excitation for which is regarded as the very combustion itself in both the chambers. Especially the time waves recorded expressed ample evidence for the suitability in replacing the conventional fuel i.e. diesel fuel. Time waves are recorded in three directions forming two on the cylinder head and one on the foundation of the engine. The recordings are presented at full load on the engine with different fuels combinations. The investigation revealed that waste cooking oil with 6% hydrated methanol proved efficient booth in the wise of combustion propensity and torque conversion. I. INTRODUCTION Diesel engines are recognized for the high level source of vibrations and sound because of the heterogeneity of combustion. In the case of open combustion chamber, the cylinder vibration is further more than the IDI engine for the same power to weight ratio. It is an established fact that the divided combustion chamber produces lesser high frequency vibration due to Helmholtz resonance principle and that is the specific reason the IDI engine is being selected for experimentation. Research on fault diagnosis of internal combustion engines is popular due their contribution to the industrial sector and condition monitoring and fault diagnosis is a valuable technique to ensure that the diesel engine stays in good order [1]. Literature in the field of vibration analysis reveals that; Vibration analysis is a difficult task due to the multiple sources of unstable and stable frequency excitations [3]. To minimize the noise levels during the operation of diesel engines, intake and exhaust silencers have been developed [2]. Some other methods like wavelet packet technique can carry out multi resolution analysis to lower the noise and to heighten signal-to-noise ratio (SNR). By this the vibroacoustic signatures can be effectively extracted from vibration responses [4]. In general diesel engine diagnostic techniques are usually developed at specific engine working conditions and on an individual engine. However, diesel engines work under different ambient conditions and load, and the dynamic features vary from engine to engine. It is desirable that a diagnostic technique can provide acceptable accuracy of diagnostic results while being insensitive to the variation of engine working conditions and engine-to-engine differences [5]. Vibration monitoring is a major technique for mechanical fault diagnosis. The vibration parameters to be measured include displacement, velocity, acceleration, and stress. However, accelerometers are deemed popular transducers for
Energy Conversion and Management, 2015
In-cylinder pressure measurement and analysis has historically been a key tool for off-line combustion diagnosis in internal combustion engines, but online applications for real-time condition monitoring and combustion management have recently become popular. The present investigation presents and compares different low computing-cost in-cylinder pressure based methods for the analyses of the main features of combustion, that is, the start of combustion, the end of combustion and the crankshaft angle that responds to half of the overall burned mass. The instantaneous pressure in the combustion chamber has been used as an input datum for the described analytical procedures and it has been measured by means of a standard piezoelectric transducer. Traditional pressure-based techniques have been shown to be able to predict the burned mass fraction time history more accurately in spark ignition engines than in diesel engines. The most suitable pressure-based techniques for both spark ignition and compression ignition engines have been chosen on the basis of the available experimental data. Timefrequency analysis has also been applied to the analysis of diesel combustion, which is richer in events than spark ignited combustion. Time frequency algorithms for the calculation of the mean instantaneous frequency are computationally efficient, allow the main events of the diesel combustion to be identified and provide the greatest benefits in the presence of multiple injection events. These algorithms can be optimized and applied to onboard diagnostics tools designed for real control, but can also be used as an advanced validation tool for refined combustion models. The presented results on the pressure-based techniques, including a time frequency analysis, have been compared with the numerical outcomes from previously developed two-and three-zone thermodynamic combustion models.
Monitoring of some functional parameters for an internal-combustion engine
2008
This work presents the achievement of a monitoring, recording, processing and interpretation concept, at laboratory scale, of some functional parameters for a spark-ignition engine, based on an electronic equipment, which measures the values of 17 parameters that describe the operation of an internal-combustion engine. In order to be able to control the optimal operation of an internal-combustion engine, an important parameter that should be measured is the pressure in the combustion chamber, which has high values (50-70 bar), the developed temperature is high and the frequency of appearance is high (depending on the crankshaft's speed). The measured pressure depends on the crankshaft's position. Is used a pressure transducer with strain-gauge socket, and measurement of the crankshaft's position with a speed transducer with variable reluctance. From experimental data, on one hand, can be analyzed the pressure modification in the combustion chamber depending on the crankshaft's position, and on the other hand, the maximum pressure modification in the cylinder depending on the speed.
Volume 1: Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant, 2017
The combustion duration in an internal combustion engine is the period bounded by the engine crank angles known as the start of combustion (SOC) and end of combustion (EOC), respectively. This period is essential in analysis of combustion for the such as the production of exhaust emissions. For compression-ignition engines, such as diesel engines, several approaches were developed in order to approximate the crank angle for the start of combustion. These approaches utilized the curves of measured in-cylinder pressures and determining by inspection the crank angle where the slope is steep following a minimum value, indicating that combustion has begun. These pressure data may also be utilized together with the corresponding cylinder volumes to generate the apparent heat release rate (AHRR), which shows the trend of heat transfer of the gases enclosed in the engine cylinder. The start of combustion is then determined at the point where the value of the AHRR is minimum and followed by ...