Engine Speed Fluctuations Research Articles

New energy vehicle engine speed control method based on vehicle networking technology

In view of the current new energy vehicles only implement torque control on the drive motor, resulting in the engine speed fluctuation, affecting the vehicle running stability and reducing the engine efficiency and energy saving effect, a new energy vehicle engine speed control method based on Internet of vehicles technology is proposed. The battery and operation data are obtained through the sensor of the new energy vehicle Internet of vehicles, and the data are controlled and transmitted by the controller area network. The overall external dynamic characteristics of the engine are analyzed by using the average value model. According to the principle of engine dynamic system, the throttle intake manifold model, combustion torque model and power output sub model are constructed respectively. The speed is controlled by double working points According to the variable parameter PID control of the engine, the load prediction is introduced to optimize the speed control, and the internal pressure value of the accumulator is obtained through the SOP value to realize the speed control of the new energy vehicle engine. The experimental results show that the engine speed control method can effectively improve the energy-saving effect and efficiency of the engine, reduce the engine speed fluctuation, and improve the vehicle running stability under the condition of meeting the driver’s torque demand.

Effects on the transient energy distribution of turbocharging mode switching for marine diesel engines

Nowadays, the high-power density and high efficiency of marine diesel engines make the requirements of high boost pressure and wide-range intake flow increased. In this study, a two-stage sequential turbocharging (TSST) system is presented as a method for increasing the power density and broadening the efficient working range of diesel engines. Through experimental and analysis methods, the relationships of intake and exhaust energy migration and exhaust energy distribution in the turbocharging mode switching process of the TSST system are investigated, and the optimal control strategy for the switching valves is obtained. The experimental results show that the optimized valve control strategy can achieve a reasonable distribution and efficient utilization of exhaust energy during the switching process. More specifically, the boost pressure error function is only 0.0003 kPa2·s, the engine speed fluctuation amplitude is less than 6 r/min, and the speed transition time is less than 8 s. A smooth switching between the turbocharging modes of the TSST system is achieved, exhaust energy loss is minimized, and the fuel economy and power performance of marine diesel engines over the entire range of operating conditions are effectively improved.

Dynamic Model and Dynamic Response of Automobile Dual‐Mass Flywheel with Bifilar‐Type Centrifugal Pendulum Vibration Absorber

Compared with dual‐mass flywheel (DMF) and DMF with simple‐type centrifugal pendulum vibration absorber (CPVA), DMF with bifilar‐type CPVA has a better damping performance in the whole speed range of engine. The related research mainly focused on local models, such as dynamic model of DMF and dynamic model of CPVA, and the effect of the curvature path of CPVA on the damping performance. The reported models and methods are not sufficient for the system of DMF coupled with bifilar CPVA. Aiming at the deficiency of local models and the limitation of bench test, an integral model for DMF with bifilar CPVA is proposed and the real vehicle test is carried out in this study. Involving the moment of inertia of the centrifugal pendulum, the model considers the nonlinearities of DMF and bifilar CPVA. Afterward, the dynamic model of the automobile power transmission system equipped with the DMF with bifilar‐type CPVA is built, and the dynamic responses of the system are investigated under idling and driving conditions. According to the simulation results, DMF with bifilar‐type CPVA shows better vibration reduction performance in full‐speed range. Moreover, the key structural parameters R and l influencing the damping performance of DMF with bifilar CPVA are discussed. The results show that the sum of R and l is directly proportional to the damping effect. Finally, real vehicle tests under idling and driving conditions (engine speed from 750 r/min to 3400 r/min) are carried out. The test results show that the 2nd order engine speed fluctuations are attenuated by more than 80% by DMF with bifilar CPVA with engine speed lower than 2000 r/min and are attenuated by more than 90% with engine speed higher than 2000 r/min. The experimental results are basically consistent with the simulation results, which verify the validity of the model.

In-cylinder pressure reconstruction by engine acoustic emission

The importance of the in-cylinder pressure transducer has been proven in revealing the information about combustion and exhaust pollution formation, as well as for its capability to classify knock. Due to their high price, they are not used commercially for engine health monitoring, which is of significant importance. Hence, this study will investigate the reconstruction of the in-cylinder pressure trace using a structure-borne acoustic emission (AE) sensor, which are relatively low cost sensors. As shown in the literature, AE indicators show a strong correlation with in-cylinder pressure parameters in both time and crank angle domain. In this study, to avoid the effect of engine speed fluctuations, the reconstruction is done in the crank angle domain by means of the Hilbert transform of AE. Complex cepstrum signal processing analysis with a feed-forward neural network is used to generate a reconstruction regime. Furthermore, the reconstructed signals are used to determine some of the important in-cylinder parameters such as peak pressure (PP), peak pressure timing (PPT), indicated mean effective pressure (IMEP) and pressure rise rate. Results showed that the combination of cepstrum analysis with neural network is capable of reconstructing pressure using AE, regardless of engine load, speed and fuel type. The reconstructed pressure can be used to reliably determine PP and PPT. IMEP can be estimated as well in a reasonable range.

Optimization of PID Governor Coefficient for Turbocharged Diesel Engine

The objective of this study is to find optimum governor coefficient for which fluctuation of engine speed is minimum, for given value of engine, turbo-charger, inlet and exhaust manifold characteristics. Current study uses the Wishnegradski Stability Diagram as suggested by V. I. Krutov [1], which graphically represents the dynamic response of governor based on the engine differential equation which is of the third order. For the load type of L = B cos (wt): The objective function is designed to minimize the integral squared error over a time period T, which is taken as 5seconds.

Modelling of the operation of a Dual Mass Flywheel (DMF) for different engine-related distortions

ABSTRACTThe application of Dual Mass Flywheels (DMF) was inspired by the need to reduce the level of vibrations generated by the drivetrain. The DMF input parameters are a result of the engine operation, in which the cyclicity of the subsequent strokes results in a variation of the engine speed. The fewer the cylinders the greater the engine speed variation and fluctuation of the engine torque. Additionally, the engine speed and torque variations are influenced by distortions, which is why the author attempted to develop a mathematical model of a DMF based on the motion equation. The methodology of calculations was also presented. For simplification, the moment of resistance generated by the drivetrain was assumed as constant. The simulation model checked out as correct and its sensitivity to small changes of the input parameters was confirmed. The mathematical description, despite simplifications, may find application in modelling of drivetrains fitted with DMF.

Ограничение колебаний электромагнитного момента асинхронного двигателя при скалярном частотном управлении

The paper presents mathematical models of induction motor as a system of equations and a structure. It also suggests the correction methods of induction motor with scalar control, which decrease fluctuations of electromagnetic torque. The graphs of the transients of the frequency-controlled electric drive with scalar control, obtained based on the mathematical model with and without additional correction device, are given. The presented scalar control system for induction motor allows starting the electric drive and regula­ting the speed with the stabilization of the electromagnetic torque of induction motor with a maximum deviation from the mean value under 5 %, as well as suppressing the engine speed fluctuations in transient modes. The frequency-controlled electric drives with induction motor and scalar control with improved dynamic properties can be applied in metallurgical mechanisms.

An Approach for Power Generation with Reduced Fuel Consumption using PTO Driven Generator

Using the gear up throttle down concept, suitable power take off (PTO) speed required to run a PTO powered generator was decided. For this PTO test was carried out using an eddy current dynamometer. The tractor engine was loaded to different torque values at different engine speeds for obtaining constant PTO power corresponding to the full load of the generator. Fuel consumption, smoke level, exhaust gas temperature and coolant temperature were measured during PTO test. Engine speed fluctuation and engine overloading were also observed to judge whether the engine was running smoothly, or it was overloaded. The specific fuel consumption was reduced from 268.9 g/kW h at 1579 rpm to 242.9 g/kW h at 1000 rpm. Considering the engine speed fluctuation, overloading of the engine, rapid rise of smoke level, exhaust gas temperature and coolant temperature, an engine speed of 1215 rpm was recommended instead of 1579 rpm (corresponding to standard PTO speed of 540 rpm). A suitable power transmission system comprising belt and pulley drive was designed to run the generator at rated speed of 1500 rpm. When the generator was operated at reduced PTO speed of 415 rpm (corresponding to engine speed of 1215 rpm) in comparison to standard PTO speed of 540 rpm, fuel saving of 0.35 l/h to 0.55 l/h and 0.43 l/h to 0.48 l/h was achieved at different alternating current (AC) and direct current (DC) loads on the generator, respectively. Following this approach, a considerable amount of fuel energy could be saved while generating electric power using tractor. Efficient use of fuel will reduce the overall production cost of agricultural products as well as help in protecting our environment.

Vibration isolation with clutch disk pre-damper mechanism for the idle rattle phenomenon

In this paper, the influence of clutch disk pre-damper mechanism constituents on the idle rattle phenomenon was investigated with an analytical model containing a new time-varying gear mesh stiffness function. Comparing experimental results to simulation results for the same excitation input was the key implementation for the validation of proposed model. The engine speed fluctuations represented in the simulation was imported from a speed measurement of a diesel engine in the test bench.

Misfire Detection of Spark Ignition Engines Using a New Technique Based on Mean Output Power

Control and detection of misfire are an essential part of on-board diagnosis (OBD) of modern spark ignition (SI) engines. This study proposes a novel model-based technique for misfire detection for a multicylinder SI engine. The new technique uses a dynamic engine model to determine mean output power, which is then used to calculate a new parameter for misfire detection. The new parameter directly relates to combustion period and is sensitive to engine speed fluctuations caused by misfire. The new technique requires only measured engine speed data and is computationally viable for use in a typical engine control unit (ECU). The new technique is evaluated experimentally on a four-cylinder 1.6-l SI engine. Three types of misfire are studied including single, continuous, and multiple-event. The steady-state and transient experiments were done for a wide range of engine speeds and engine loads, using a vehicle chassis dynamometer and on-road vehicle testing. The validation results show that the new technique is able to detect all three types of misfire with up to 94% accuracy during steady-state conditions. The new technique is augmented with a compensation factor to improve the accuracy of the technique for transient operations. The resulting technique is shown to be capable of detecting misfire during both transient and steady-state engine conditions.

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

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.

Three-dimensional numerical analysis of diesel combustion under cold ambient conditions

A lower compression ratio has been demanded for diesel engines in recent years to improve fuel consumption, exhaust emissions and maximum power recently. However, low compression ratio may have combustion instability issues under cold temperature condition, especially just after engine started. As the first step in this study, cold temperature combustion was investigated on the basis of an in-cylinder pressure analysis, and it was found that higher heat release around top dead center, which was mainly attributed to pilot injection, was a key factor in reducing engine speed fluctuation. Three-dimensional computational fluid dynamics simulations were conducted to obtain a better understanding of combustion under cold condition, particularly mixture formation near the glow plug. Specifically, for this purpose, a time-scale interaction combustion model was developed for simulating combustion phenomena. This model was based on a reasonable combustion mode, taking into account the characteristic time scale of chemical reactions and turbulence eddy breakup. In addition, the parameters of the ignition model and computational grids near the glow plug were improved for application to cold start conditions.

Diesel Engine Combustion Sensing Methodology Based on Vibration Analysis

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.

Comparison of particle mass and number emissions from a diesel transit bus across temporal and spatial scales

This study analyzes particle number and mass emission rates measured from the exhaust of a 2002 diesel transit bus in real-world driving conditions. The dynamics of the particle number and mass emission rates are examined at resolved temporal and spatial scales across an urban arterial, a rural arterial and a divided freeway. Time-based particle number and mass emission rates were highest on the freeway, but the distance-based particle emission rates of emission/km at “hot-spots” for exposure assessment for selected 50-m road segments occurred at intersections when the bus accelerated from a stop or traveled up high grades. Comparisons of particle mass and number emission rates between idling and acceleration indicate that unless the bus is extending idling for several minutes, public exposure to bus particle emissions near bus stops can be mainly attributed to accelerations. Generally, particle number and mass emissions rates are highly correlated both temporally and spatially. Some deviations occur because particle mass emissions are highly elevated during sustained fueling events such as traveling on high grades and during sustained accelerations, while particle number emissions are more sensitive to fuel and engine speed fluctuations.

A study of integral sliding mode control with input constraint for engine idling‐speed control

AbstractThis paper proposes an approach to the provision of sliding mode control (SMC) with input constraint for engine idling‐speed control. The aim of this experiment is to improve the stability of the system against disturbances such as fuel purges and torque loads. A steady‐state error occurs because, in practice, the control input is restricted when an integral type SMC is employed to achieve stabilization. A modification to this approach is proposed that effectively uses compensation gain and variable switching gain. The compensation gain is derived from the control input difference, and the variable switching gain is described as an exponential function of the hyperplane. A mean‐value engine model with dead time and disturbances is constructed in Matlab/Simulink. The simulation results show that the issue relating to steady‐state deviation can be successfully solved with regard to disturbances having bias power; also, robustness is maintained during engine speed fluctuations. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Idle speed performance improvement via torque balancing control in ignition-event scale for SI engines with multi-cylinders

Imbalance in torque generation leads to engine speed fluctuation. To improve the idle engine speed performance, the torque balancing control problem is addressed in this paper for multi-cylinder SI engines. To evaluate cylinder-to-cylinder imbalance, the average torque in ignition-event scale is introduced as controlled output, which enables a feedback control to be performed without measurement of instantaneous torque, and the individual spark advances are chosen as control inputs. A linear discrete time model with single input and single output is proposed to represent the dynamics of the imbalance, where a sequentially switching function is introduced to describe the spark advance signals delivered to each cylinder and the differences in torque generation caused by the individual cylinder characteristics are equivalently modelled as unknown offset in the inputs. An estimation algorithm with the proof of convergence is presented to provide on-line estimation of the unknown offset under the passivity assumption of the system. Furthermore, a feedback control law which combines the unknown offset estimation and the model predictive control is proposed. Finally, the unknown offset estimation and the feedback control approach are validated based on the experimental results carried out on a six-cylinder gasoline engine test bench.

Effect of hydrogen addition on the idle performance of a spark ignited gasoline engine at stoichiometric condition

Abstract With regard to the improvement of efficiency, combustion stability, and emissions in a gasoline engine at idle condition, an experimental study aimed at improving engine idle performance through hydrogen addition was carried out on a 4-cylinder gasoline-fueled spark ignited (SI) engine. The engine was modified to be fueled with the mixture of gasoline and hydrogen injected into the intake ports simultaneously. A self-developed electronic control unit (DECU) was dedicatedly used to control the injection timings and injection durations of gasoline and hydrogen. Other parameters, such as spark timing and idle valve opening, were controlled by the original engine electronic control unit (OECU). Various hydrogen enrichment levels were selected to investigate the effect of hydrogen addition on engine speed fluctuation, thermal efficiency, combustion characteristics, cyclic variation and emissions under idle and stoichiometric conditions. The experimental results showed that thermal efficiency, combustion performance, NO x emissions are improved with the increase of hydrogen addition level. The HC and CO emissions first decrease with the increasing hydrogen enrichment level, but when hydrogen energy fraction exceeds 14.44%, it begins to increase again at idle and stoichiometric conditions.

Analytical and Numerical Dynamic Analysis of Gears in the Presence of Engine Acyclism

A one-degree-of-freedom model of geared transmissions is set up. It incorporates the influence of unsteady rotations due to engine speed fluctuations along with simplified time-varying mesh stiffness functions, including contact losses between the teeth and back strikes. The dynamic tooth loads are determined by several analytical and numerical techniques whose results agree well. Finally, some of the response characteristics due to speed fluctuations are presented and commented upon.

Analysis of the Interactions Between Indicated and Reciprocating Torques for the Development of a Torsional Behavior Model of the Powertrain

Torque-based engine control systems usually employ a produced torque estimation feedback in order to verify that the strategy target torque has been met. Torque estimation can be performed using static maps describing the engine behavior or using models describing the existing relationships between signals measured on the engine and the indicated torque produced. Signals containing information on the combustion development, suitable for this purpose, are, among others, the ion-current signal, the vibration signals obtained from accelerometers mounted on the engine block, or the instantaneous engine speed fluctuations. This paper presents the development and the identification process of an engine-driveline torsional behavior model that enables indicated torque estimation from instantaneous engine speed measurement. Particular attention has been devoted to the interactions between indicated and reciprocating torques, and their effects over instantaneous engine speed fluctuations. Indicated and reciprocating torques produce, in fact, opposite excitations on the driveline that show opposite effects on the engine speed wave form: For low engine speed, usually indicated torque prevails, while the opposite applies for higher engine speed. In order to correctly estimate indicated torque from engine speed measurement, it is therefore necessary to correctly evaluate the reciprocating torque contribution. Reciprocating torque is usually described using a wave form as a function of crank angle, while its amplitude depends on the value of the reciprocating masses. As mentioned before, knowledge of the reciprocating masses is fundamental in order to obtain correct estimation of the indicated torque. The identification process that has been set up for the engine-driveline torsional model enables to evaluate the relationship between torques applied to the engine and the corresponding engine speed wave form even without knowing the value of the reciprocating masses. In addition, once this model has been set up, it is possible to estimate with high precision the value of the reciprocating masses. Particular attention has also been devoted to the feasibility of the application of the identified model onboard for torque estimation; for this reason, the model has been developed in a very simple form. The approach proved to be effective both on gasoline and diesel engines, both for engine mounted on a test cell and onboard, with different engine configurations. Examples of application are given for some of the configurations investigated.

Instability analysis in oscillators with velocity-modulated time-varying stiffness—Applications to gears submitted to engine speed fluctuations

A one degree-of-freedom model is set up which incorporates time-varying mesh stiffness functions and the influence of unsteady input rotations due to engine speed fluctuations. The stability of the associated parametrically excited system is analysed by calculating the monodromy matrix via a Newmark scheme. A piecewise constant and a sinusoidal mesh stiffness functions are considered and it is shown that additional side-band instability zones are generated because of frequency modulations. The influence of the mesh stiffness variations and damping is discussed.