Torque and Center of Combustion Evaluation Through a Torsional Model of the Powertrain

Author(s):  
Fabrizio Ponti ◽  
Vittorio Ravaglioli ◽  
Matteo De Cesare ◽  
Federico Stola

The continuous development of modern internal combustion engine (ICE) management systems is mainly aimed at combustion control improvement. Nowadays, performing an efficient combustion control is crucial for drivability improvement, efficiency increase (critical for spark ignited engines), and pollutant emissions reduction (critical in compression ignited engines). The most important quantities used for combustion control are engine load (indicated mean effective pressure (IMEP) or torque delivered by the engine) and center of combustion, i.e., the angular position in which 50% of fuel burned within the engine cycle is reached. Both quantities can be directly evaluated starting from in-cylinder pressure measurement, which could be performed using the newly developed piezoresistive pressure sensors for on-board applications. However, the use of additional sensors would increase the cost of the whole engine management system. Due to these reasons, over the past years, a methodology that allows evaluating both engine load and the center of combustion with no extra cost has been developed. This approach is based on engine speed fluctuation measurement, which can be performed using the same speed sensor already mounted on-board. The methodology is general and can be applied to different engine–driveline systems with different architectures and combustion orders. Furthermore, it is compatible with on-board requirements, since the evaluation of only one specific harmonic component of interest is required (depending on the engine–driveline configuration under investigation). In order to clarify all the issues related to the application of the presented approach, it has been applied to some different engines, both compression ignited and spark ignited, taking also into account the case of combustion not evenly spaced. For all the analyzed configurations, the results obtained using the estimation algorithm seemed to be adequate to feedback a closed-loop methodology for optimal combustion control.

Author(s):  
Fabrizio Ponti ◽  
Vittorio Ravaglioli ◽  
Gabriele Serra

As a result of the increasing request to reduce pollutant emissions and improve efficiency in modern Internal Combustion Engines, it is important to know a high number of quantities that are representative of the combustion process. One of the most important parameters to estimate on-board is the angular position where 50% of fuel mass injected over an engine cycle is burned (MFB50), because it provides information about the effectiveness of combustion (useful, for example, in HCCI combustion control). MFB50 can be evaluated using in-cylinder pressure sensors, nevertheless they would cause engine control systems cost to rise. The MFB50 estimation algorithm presented in this work is based on engine speed measurement, that can be performed using the same 60-2 toothed wheel already present on-board for other control purposes. For the above reason, this approach is not only compatible with on-board applications, it also requires no additional costs. The developed method mainly consists of 2 parts. The first one is to determine the relationship between the engine speed harmonic components and the corresponding indicated torque harmonic components, expressed as a Frequency Response Function representative of the engine-load system’s torsional behavior. After having estimated the indicated torque harmonic component, the following step is to estimate the value of MFB50 cycle by cycle. This is done analyzing the relationships between the indicated torque harmonic components phase and the angular position where 50% of the fuel injected over the engine cycle is burned. The procedure has been applied to an L4 turbocharged Diesel engine mounted on-board a vehicle, obtaining an estimation accuracy adequate enough to feedback a control algorithm for optimal combustion positioning over an engine cycle.


Author(s):  
Ponti Fabrizio ◽  
Ravaglioli Vittorio ◽  
Cavina Nicolò ◽  
De Cesare Matteo

The increasing request for pollutant emissions reduction spawned a great deal of research in the field of combustion control and monitoring. As a matter of fact, newly developed low temperature combustion strategies for diesel engines allow obtaining a significant reduction both in particulate matter and NOx emissions, combining the use of high EGR rates with a proper injection strategy. Unfortunately, due to their nature, these innovative combustion strategies are very sensitive to in-cylinder thermal conditions. Therefore, in order to obtain a stable combustion, a closed-loop combustion control methodology is needed. Many works demonstrate that a closed-loop combustion control strategy can be based on real-time analysis of in-cylinder pressure trace that provides important information about the combustion process, such as start of combustion, center of combustion and torque delivered by each cylinder. Nevertheless, cylinder pressure sensors on-board installation is still uncommon, due to problems related to unsatisfactory measurement long term reliability and cost. This paper presents a newly developed approach that allows extracting information about combustion effectiveness through the analysis of engine vibrations. In particular, the developed methodology can be used to obtain an accurate estimation of the indicated quantities of interest combining the information provided by engine speed fluctuations measurement and by the signals coming from acceleration transducers mounted on the engine. This paper also reports the results obtained applying the whole methodology to a light-duty turbocharged common rail diesel engine.


1999 ◽  
Vol 121 (3) ◽  
pp. 487-495 ◽  
Author(s):  
Yong Wha Kim ◽  
Giorgio Rizzoni ◽  
Yue-Yun Wang

The torque produced by each combustion in an engine is one of the most important indices tied to internal combustion engine performance. In this paper, an approach is investigated to estimate engine torque. Instead of employing expensive and delicate combustion pressure sensors to directly measure indicated pressure in each cylinder, unknown input observers are exploited to estimate cylinder indicated torque using one or more low-cost measurements of crankshaft angular position. Necessary and sufficient conditions for the existence of such torque estimators for multi-cylinder engines are presented in the paper; these include the number of angular position sensors required and their suggested placement. Model reduction issues and the number of measurements required to obtain an acceptable estimate are also considered. The approach is applied to a six-cylinder industrial diesel engine.


Author(s):  
F. Ponti ◽  
V. Ravaglioli ◽  
N. Cavina ◽  
M. De Cesare

The increasing request for pollutant emissions reduction spawned a great deal of research in the field of combustion control and monitoring. As a matter of fact, newly developed low temperature combustion strategies for Diesel engines allow obtaining a significant reduction both in particulate matter and NOx emissions, combining the use of high EGR rates with a proper injection strategy. Unfortunately, due to their nature, these innovative combustion strategies are very sensitive to in-cylinder thermal conditions. Therefore, in order to obtain a stable combustion, a closed-loop combustion control methodology is needed. Many works demonstrate that a closed-loop combustion control strategy can be based on real-time analysis of in-cylinder pressure trace, that provides important information about the combustion process, such as start of combustion, center of combustion and torque delivered by each cylinder. Nevertheless, cylinder pressure sensors on-board installation is still uncommon, due to problems related to unsatisfactory measurement long term reliability and cost. This paper presents a newly developed approach that allows extracting information about combustion effectiveness through the analysis of engine vibrations. In particular, the developed methodology can be used to obtain an accurate estimation of the indicated quantities of interest combining the information provided by engine speed fluctuations measurement and by the signals coming from acceleration transducers mounted on the engine. This paper also reports the results obtained applying the whole methodology to a light-duty turbocharged Common Rail Diesel engine.


Author(s):  
Fabrizio Ponti ◽  
Vittorio Ravaglioli ◽  
Matteo De Cesare

Optimal combustion control has become a key factor in modern automotive applications to guarantee low engine out emissions and good driveability. To meet these goals, the engine management system has to guarantee an accurate control of torque delivered by the engine and optimal combustion phasing. Both quantities can be calculated through a proper processing of in-cylinder pressure signal. However, in-cylinder pressure on-board installation is still uncommon, mainly due to problems related to pressure sensors' reliability and cost. Consequently, the increasing request for combustion control optimization spawned a great amount of research in the development of remote combustion sensing methodologies, i.e., algorithms that allow extracting useful information about combustion effectiveness via low-cost sensors, such as crankshaft speed, accelerometers, or microphones. Based on the simultaneous acquisition of two crankshaft speed signals, this paper analyses the information that can be extracted about crankshaft's torsional behavior through a proper processing of the acquired signals. In particular, the correlations existing between such information and indicated quantities (torque delivered by the engine and combustion phasing) have been analyzed. In order to maximize the signal-to-noise ratio, each speed measurement has been performed at an end of the crankshaft, i.e., in correspondence of the flywheel and the distribution wheel. The presented approach has been applied to a light-duty L4 diesel engine mounted in a test cell. Nevertheless, the methodology is general, and it can be applied to engines with a different number of cylinders, both compression ignition (CI) and spark ignition (SI).


Author(s):  
F. Ponti ◽  
V. Ravaglioli ◽  
M. De Cesare

Optimal combustion control has become a key factor in modern automotive applications to guarantee low engine out emissions and good driveability. In order to meet these goals, the engine management system has to guarantee an accurate control of torque delivered by the engine and optimal combustion phasing. Both quantities can be calculated through a proper processing of in-cylinder pressure signal. However, in-cylinder pressure on-board installation is still uncommon, mainly due to problems related to pressure sensors’ reliability and cost. Consequently, over the last years, the increasing request for combustion control optimization spawned a great amount of research in the development of remote combustion sensing methodologies, i.e. algorithms that allow extracting useful information about combustion effectiveness via low cost sensors, such as crankshaft speed, accelerometers or microphones. Based on the simultaneous acquisition of two crankshaft speed signals, this paper analyses the information that can be extracted about crankshaft’s torsional behavior through a proper processing of the acquired signals. In particular, the correlations existing between such information and indicated quantities (torque delivered by the engine and combustion phasing) have been analysed. In order to maximize the signal-to-noise ratio, each speed measurement has been performed at an end of the crankshaft, i.e. in correspondence of the flywheel and the distribution wheel. The presented approach has been applied to a light-duty L4 Diesel engine mounted in a test cell. Nevertheless, the methodology is general, and it can be applied to engines with a different number of cylinders, both CI and SI.


Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3408
Author(s):  
Jingeun Song ◽  
Junepyo Cha

Internal combustion engine emissions are a serious worldwide problem. To combat this, emission regulations have become stricter with the goal of reducing the proportion of transportation emissions in global air pollution. In addition, the European Commission passed the real driving emissions–light-duty vehicles (RDE-LDV) regulation that evaluates vehicle emissions by driving on real roads. The RDE test is significantly dependent on driving conditions such as traffic or drivers. Thus, the RDE regulation has the means to evaluate driving dynamics such as the vehicle speed per acceleration (v·apos) and the relative positive acceleration (RPA) to determine whether the driving during these tests is normal or abnormal. However, this is not an appropriate way to assess the driving dynamics because the v⋅apos and the RPA do not represent engine load, which is directly related to exhaust emissions. Therefore, in the present study, new driving dynamic variables are proposed. These variables use engine acceleration calculated from wheel force instead of the acceleration calculated from the vehicle speed, so they are proportional to the engine load. In addition, a variable of driving dynamics during braking is calculated using the negative wheel force. This variable can be used to improve the accuracy of the emission assessment by analyzing the braking pattern.


2019 ◽  
Vol 8 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Dennis Vollberg ◽  
Dennis Wachter ◽  
Thomas Kuberczyk ◽  
Günter Schultes

Abstract. Different sensor concepts for time-resolved cylinder pressure monitoring of combustion engines are realized and evaluated in this paper. We distinguish a non-intrusive form of measurement outside the cylinder, performed by means of a force compression rod from intrusive, real in-cylinder measurement by means of pressure membrane sensors being exposed to the hot combustion process. The force compression rod has the shape of a sine wave with thinner zones equipped with highly sensitive foil strain gauges that experience a relatively moderate temperature level of 120 ∘C. The sensor rod delivers a relative pressure value that may be influenced by neighbour cylinders due to mechanical coupling. For the intrusive sensor type, two different materials for the membrane-type sensor element were simulated and tested, one based on the ceramic zirconia and the other based on stainless steel. Due to the higher thermal conductivity of steel, the element experiences only 200 ∘C while the zirconia element reaches 300 ∘C. Metallic chromium thin films with high strain sensitivity (gauge factor of 15) and high-temperature capability were deposited on the membranes and subsequently structured to a Wheatstone bridge. The pressure evolution can be measured with both types in full detail, comparable to the signals of test bench cylinder pressure sensors. For the preferential steel-based sensor type, a reliable laser-welded electrical connection between the thin films on the membrane and a copper wire was developed. The in-cylinder pressure sensors were tested both on a diesel test bench and on a gas-fired engine. On the latter, an endurance test with 20 million cycles was passed. Reliable cylinder pressure sensors with a minimum of internal components are thus provided. The signals will be processed inside the sensor housing to provide analysis and aggregated data, i.e. mass fraction burned (MFB50) and other parameters as an output to allow for smart combustion control.


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