Crank Position Research Articles

Development of a CFD Model and Validation with PIV-data to Study the Fluid Motion in a Small PFI SI Engine

In-cylinder fluid motion has a substantial impact on air-fuel mixture formation, combustion process and emission formation. In the present paper, a simulation study of the in-cylinder fluid flow is performed using a computational fluid dynamic (CFD) model of a port-fuel-injection (PFI) engine (volume: 110 cc). First, a 1-D model is developed, and validated with the cylinder pressure traces acquired in an optical engine experimentally. The model provided the boundary conditions for multi-dimensional numerical simulations. The predicted velocity fields from CFD are then compared with the measured data obtained using particle image velocimetry (PIV) at various crank angle positions with low throttle opening condition. A good relevance is observed on comparing numerically estimated results with experimental results.

Investigation of fuel effects on the knock under lean burn conditions in a spark ignition engine

In this study, the fuel effects on the knock under super lean burn conditions were investigated using a single-cylinder spark ignition (SI) engine with a compression ratio of 15 at an excess air ratio of 1.8. Four types of test fuels with different ignition characteristics were used. The knock occurred before the minimum spark advance for the best torque in all conditions. The octane number and octane index did not show good correlation with the crank angle position at which 50% of the heat was released (CA50) at the knock limit obtained in the experiments. The crank angle when the calculated Livengood-Wu integral (LWI) value = 1 did not precisely predict the knock onset. The F value proposed in this study was in reasonable agreement with CA50 at the knock limit. It was composed of the following three factors: the crank angle (its unit is degree after top dead center) when LWI = 1, h value representing the differences in the low-temperature oxidation behavior, and gradient of ignition delay times against temperatures at the crank angle when LWI = 1. This indicates that the three factors composing the F value affected knock occurrence under super lean burn conditions using an SI engine with high compression ratio.

Torque and cadence tracking in functional electrical stimulation induced cycling using passivity-based spatial repetitive learning control

Due to the inherent periodic nature of cycling tasks, iterative and repetitive learning controllers are well motivated for rehabilitative cycling. Motorized functional electrical stimulation induced cycling is a rehabilitation treatment where multiple lower-limb muscle groups are activated jointly with an electric motor to achieve cycling objectives such as speed (cadence) and torque tracking. This paper examines torque tracking accomplished by the stimulation of six lower-limb muscles via a novel spatial repetitive learning control and cadence regulation by an electric motor using a sliding-mode controller. A desired torque trajectory is constructed based on the rider’s kinematic efficiency, which is a function of the crank position. The learning controller takes advantage of the periodicity of the desired torque trajectory to provide a feedforward input to the stimulated muscles. A passivity-based analysis is developed to ensure stability of the torque and cadence closed-loop error systems. The muscle learning and electric motor controllers were implemented in real-time during cycling experiments on five able-bodied individuals and three participants with movement disorders. The combined average cadence tracking error was 0.01±1.20 RPM for a 50 RPM trajectory and the combined average power tracking error was 1.78±1.25 W for a peak power of 10 W.

Muscle activation patterns in paralympic and novices hand cycling during incremental test

The few studies on muscle timing in hand cycling are difficult to classify in the motor skill acquirement due to their variety of methods and content. This study aims to replicate two existing studies and thus to extend and connect the current state of research concerning the muscle timing during synchronous pedalling. The activity on- and offset of biceps brachii, triceps brachii, posterior deltoid, anterior deltoid, upper trapezius, and pectoralis major were identified during an incremental test of an elite and three novice athletes. The results showed differences in inter-muscular coordination between the elite and novice hand cyclists. Although the distinction between active and inactive phases was already evident in novice data, the activation pattern of the elite athlete showed an even more precise differentiation between these two phases. These time windows remained stable even with increasing load accompanied only by changes in all signal amplitude, except for deltoid activity, which showed a later onset and offset with increasing load. Thus, in training of hand cyclist novices, the muscle timing concerning the duration and the crank position should be considered. In future studies, the effect of handicap severity and crank frequency must be studied in greater detail.

A Novel Method to Actively Damp the Vibration of the Hybrid Powertrain by Utilizing a Flywheel Integrated-Starter-Generator

In this paper, a novel method to actively damp the powertrain vibration by utilizing a flywheel integrated starter generator (FISG) is proposed and validated on the testbench. A more light-weighted, economical, and compact hybrid powertrain devoid of clutches or dampers is built by replacing its flywheel with the ISG rotor. Motor torque having the opposite phase of the engine torque is applied to reduce the vibration. As opposed to the passive methods, which usually make use of the inertial and/or the damping properties of the components to absorb the vibration, this active approach is defined as active damping. Firstly, active damping is proved to be theoretically feasible by simulation based on an engine torque observer. To get the practical-application-oriented motor torque waveform, the observer torque is then processed by considering some realistic factors, such as the motor's response delay and the torque demand limit at MCU (Motor Control Unit), and is finally simplified as the rectangular waveform by off-line simulation. Secondly, an algorithm operating on the original resolver aimed at calculating the real-time crank position is proposed and programmed directly in the MCU. Finally, active damping is realized online utilizing a feedforward method by programming the crank-torque table in MCU. Experiments in both stable and transient conditions are conducted. Results show that active damping can attenuate the vibration effectively, especially over low speed and load ranges. The speed fluctuation range and the cyclic squared angular acceleration can be reduced by 79.7% and 89.7% respectively at 700 rpm when cranking. The crank vibration in transient conditions, including dragging and free deceleration, can also be suppressed, showing potential to realize fast and quiet engine start and halt.

Cycling Biomechanics Optimization-the (R) Evolution of Bicycle Fitting.

Optimal bicycle configuration has been the topic of numerous studies. A majority of these have investigated the optimal saddle height and have used either static kinematics or two-dimensional kinematic measurements. Other joints, such as the hip, shoulder, and elbow joint, have not been investigated to any meaningful extent. There is, therefore, a paucity of data describing the optimal position of the upper body and pelvis in cycling. More recently, it has been recommended that bike fitting be conducted in a dynamic functional manner, as kinematics can be influenced by cycling workload. Full-body three-dimensional kinematics and saddle pressure are newer modalities available to the clinician. This review of the literature investigates the current research pertaining to the configuration of all components of the bicycle, from static methods to dynamic methods, and related to optimal performance and injury prevention. Setting the saddle height using the Holmes static method is optimal for injury prevention and performance. Guidelines for optimal bicycle configuration should take into account the training intensity when assessing kinematics as compensatory lower-limb kinematics occur during higher-power outputs. Optimal KFA using dynamic measurements should range from 33° to 43° at low intensity to 30° to 40° at high intensity when measured at the bottom dead center crank position. Saddle pressure mapping should ideally be performed at an intensity similar to what cyclists will encounter during the majority of their training and racing. Reference values and recommendations for dynamic assessments are still required for all other joints. Furthermore, intrinsic factors, such as training load and flexibility, which may affect bicycle configuration and performance, should be investigated to assess how these may influence the optimal bicycle configuration.

Modelling of Combustion Characteristics of a Single Curved-Cylinder Spark-Ignition Crank-Rocker Engine

A crank-rocker engine is a new invention used to convert oscillating motion from the curve-piston into the rotary motion of the crankshaft. The configuration of this new engine is different from the normal slider-crank engine, so the existing model used to calculate the combustion characteristic is not appropriate for this new engine. A fundamental thermodynamic model of a single curved-cylinder spark-ignition crank-rocker engine is presented. The model was simulated in MATLAB to predict the combustion characteristics at different operating conditions. The friction losses, residual gas fraction and combustion efficiency were introduced into the combustion model to improve the overall accuracy of the model. The developed model was used to analyze and evaluate the in-cylinder pressure, fuel burn rate, and heat release under various crank angle positions. To validate the predictions of the model, experimental tests were conducted on a single-cylinder crank-rocker engine at an engine speed of 2000 rpm, spark timing of 8.60 CA BTDC, full load and wide-open throttle (WOT) condition. Finally, the results were plotted and compared with the simulation results. The findings obtained from the current study have shown the ability of the simulation model to predict the combustion characteristics under different operating conditions. The agreement between the results of the present model and experimental data was reasonably good. This research work proposes a new model which can predict the behavior of the crank-rocker engine. The information gained from this study will aid in the tuning process and future development of this engine.

The synergy of EMG waveform during bicycle pedaling is related to elemental force vector waveform.

Background & Purpose: In recent years, the pedaling force vector can now be accurately measured using pedaling analyzer systems (bikefitting.com, Sittard, Netherlands). Using this device, we showed that the pedaling force vector components in the tangential and radial directions can be represented by the sum of two or three elemental waveform components, respectively (Kitawaki et al 2018). Besides, a previous study that analyzed the electromyogram (EMG) signals of the lower limb muscles demonstrated that pedaling is accomplished by combining three similar muscle synergies (Hug et al. 2010). Therefore, this study aims to clarify the relationship between the elemental components of the force vector and EMG synergies. We performed synergy analysis of the EMG waveform, which was measured simultaneously with the force vector. Methods: Two participants (a former professional and a top-level amateur cyclist) performed pedaling under a variety of conditions (load: 100 W, 200 W, 300 W; cadence: 70 rpm, 90 rpm, 110 rpm; saddle position: back (5 cm), forward (10 cm), up (3 cm), and down (5 cm, 10 cm); pedaling action type: normal, spinning, pulling, and pushing and pulling). Pedaling force vector data was obtained every 15° using a pedaling analyzer system (bikefitting.com). Pedaling vector data were expressed as the sum of elemental vectors, as demonstrated in our previous study (Kitawaki et al 2018). The surface EMG was synchronously measured on the dominant leg at eight locations (anterior tibialis: TA, gastrocnemius medialis: GM, soleus: SOL, rectus femoris: RF, vastus medialis: VM, biceps femoris: BF, gluteus maximus (upside: GM1, downside: GM2)). After the EMG waveforms have been rectified and integrated, the unnormalized iEMG waveforms were obtained every 5° using crank position data. A non-negative matrix factorization (NNMF) algorithm was applied to the iEMG waveforms of the pedaling cycles to differentiate muscle synergies. The number of synergies was set to five to accurately express the muscle output exerted according to the variety of pedaling conditions. Pearson's correlation coefficient between amplitude of the force vector wave and the amplitude of EMG synergy by muscle was calculated for each participant. Results & Discussion: The iEMG waveform can be represented by the sum of five synergies, as shown in Figure 1. The synergy waveforms in the figure are normalized for easy understanding, although not normalized in the NNMF calculation. The amplitude of the synergy varies with the pedaling conditions. The analysis of NNMF does not include change in phase, whereas the force vector waveform analysis includes change in phase angle. Moreover, the change in phase angle was not included in the EMG analysis as it was approximately 5°. Table 1 lists the correlation coefficient between the amplitude of five EMG synergies and three force vector amplitude (A1, A2, A3) of elemental vector waveforms for each participant. A few muscles with less muscular amplitude were removed from the table. The following can be observed from the results: Subject ID1: In the pushing phase of Synergy 2-3, the magnitude of A1 that related to pedaling power has a positive correlation with most muscular activity. On the other hand, in the recovery phases of Synergy 1 & 5, most muscular activities have negative correlation with the magnitude of A1. Thus, it seems that subject ID1 is performing more integrated pedaling. Subject ID2: By contrast, in the early pushing phase of Synergy 2-3, certain muscle (RF, VM, GM) activities increase due to the difference in pedaling, whereas some muscular (GC, SOL, BF) activities decrease. In the case of subject ID 2, the combination of various muscles changes and the pedaling action seems to be changing. These results indicate that the change in the force vector is caused by the difference in pedaling due to the difference in the muscle force activity. However there are only two participants, hence this study is a pilot study. In the future, we will continue to investigate the difference between change in the element waveform and muscle force assessment by increasing the number of participants and we will study the corresponding muscle force activity and pedaling action. Conclusion: The change in the amplitude of elemental waveform components of the force vector and the amplitude of EMG synergy are interrelated; we clarified that the force vector and the EMG waveform change at the same time due to a variety of pedaling conditions.

Crank fore-aft position alters the distribution of work over the push and pull phase during synchronous recumbent handcycling of able-bodied participants.

ObjectiveThe objective of the current study was to investigate the effect of four different crank fore-aft positions on elbow flexion and shoulder protraction, the consequent propulsion kinetics and the physiological responses during handcycling.MethodsTwelve able-bodied male participants volunteered in this study. Crank fore-aft positions were standardised at 94%, 97%, 100% and 103% of the participants’ arm length. Two submaximal 3 min trials were performed at a fixed cadence (70 rpm), in a recumbent handcyle attached to an ergometer at two fixed power outputs (30W and 60W). Elbow flexion, shoulder protraction, propulsion kinetics and physiological responses of the participants were continuously measured.ResultsAs crank fore-aft distance increased, a decrease in elbow flexion (42±4, 37±3, 33±3, 29±3°) and an increase shoulder protraction was observed (29±5, 31±5, 34±5, 36±5°). The percentage of work done in the pull phase increased as well (62±7, 65±7, 67±6, 69±8%, at 60W), which was in line with an increased peak torque during the pull phase (8.8±1.6, 9.0±1.4, 9.4±1.5, 9.7±1.4Nm, at 60W) and reduced peak torque during the push phase (6.0±0.9, 5.6±0.9,5.6±0.9, 5.4±1.0Nm, in 60W condition). Despite these changes in work distribution, there were no significant changes in gross mechanical efficiency (15.7±0.8, 16.2±1.1, 15.8±0.9, 15.6±1.0%, at 60W). The same patterns were observed in the 30W condition.ConclusionsFrom a biomechanical perspective the crank position closest to the trunk (94%) seems to be advantageous, because it evens the load over the push and pull phase, which reduces speed fluctuations, without causing an increase in whole body energy expenditure and hence a decrease of gross mechanical efficiency. These findings may help handcyclists to optimize their recumbent handcycle configuration.

Horizontal Crank Position Affects Economy and Upper Limb Kinematics of Recumbent Handcyclists.

To determine the effects of horizontal crank position on economy and upper limb kinematics in recumbent handcycling. Fifteen trained handcyclists performed trials at 50% and 70% of their peak aerobic power output (POPeak), determined during a maximal exercise test, in each horizontal crank position. Four horizontal crank positions, 94%, 97%, 100%, and 103% of arm length, were investigated. Horizontal crank positions were defined as the distance between the acromion angle to the center of the handgrip, while the crank arm was parallel to the floor and pointing away from the participant. Economy and upper limb kinematics were calculated during the final minute of each 3-min trial. Horizontal crank position significantly affected handcycling economy at 70% POPeak (P < 0.01) but not at 50% POPeak (P = 0.44). The 97% horizontal crank position (16.0 [1.5] mL·min·W) was significantly more economical than the 94% (16.7 (1.9) mL·min·W) (P = 0.04) and 103% (16.6 (1.7) mL·min·W) (P < 0.01) positions. The 100% horizontal crank position (16.2 (1.7) mL·min·W) was significantly more economical than the 103% position (P < 0.01). Statistical parametric mapping indicated that an increase in horizontal crank position, from 94% to 103%, caused a significant increase in elbow extension, shoulder flexion, adduction, internal rotation, scapular internal rotation, wrist flexion, clavicle depression and clavicle protraction between 0% and 50% (0°-180°) of the cycle (P < 0.05). Positioning the cranks at 97% to 100% of the athletes' arm length improved handcycling economy at 70% POPeak as, potentially, the musculature surrounding the joints of the upper limb were in a more favorable position to produce force economically.

Simulation and experimental response of four-bar mechanism with tolerance stack

An Equivalent Contact Stiffness (ECS) approach is proposed in this article to estimate the precise contact parameters for a revolute joint. Estimated contact parameters are used as input variables for the MBD simulation of a four-bar mechanism with tolerance stack. Simulations were carried out using Impact Force Method (IFM) and Restitution Method (RM) in MSC ADAMS. An experimental setup of the four-bar mechanism is developed with a unique feature to measure the angular velocity of the follower with respect to the crank position. The effect of tolerance stack on the angular velocity of the follower is investigated experimentally to validate the MBD simulation. The angular velocity of coupler and rocker is increased by 15.69% and 27% respectively due to tolerance stack. MBD analysis using the ECS approach provides accurate and reliable results in absence of experimental contact data. This work shall facilitate the designers to simulate the actual behaviour of the mechanism prior to prototype.

DETERMINATION OF THE INPUT PARAMETERS OF THE WORK-STREAM OF THE OIL-GAS EJETOR USED SIMULTANEOUSLY WITH THE SUCKER-ROD PUMP

In order to calculate the working mode of a sucker-rod pump driven by the beam pumping unit and a jet pump during their simultaneous operation, pressure and temperature distribution along the wellbore from the bottom to the wellhead is determined for the real oil well 753-D "Dolynanaftogaz" Field Office. To calculate these parameters an improved methodology based on known Poettmann-Carpenter and Baxendel methods is used. As a result, the imperfection of these methods was eliminated, namely the assumption that pressure and temperature behavior along the wellbore is linear. This led to obtaining results which are up to 23% more accurate. In addition, using the algorithm for determining the density of perfect (ideal) liquid-gas mixture, the author has calculated the velocities of gas-water-oil and water-oil mixtures for a number of sections along the production tubing at different angles of the crank position in the beam pumping unit. The indicated values make it possible to determine the depth of the oilgas jet pump location in the well, and, consequently, the parameters at its input (pressure, temperature, velocity of the liquid-gas mixture, its density, etc.). Besides, the author studies the dependence which describes the behavior of the liquid-gas mixture density along the wellbore, as well as the relations between the density of the free oil gas, thevolumetric consumption gas content of the flow and the placement of the section under consideration. All of the above-mentioned algorithms were implemented using developed computer programs. The obtained results give a possibility to choose the location of the jet pump in the well which is the most advantageous one for ensuring maximum pressure reduction and the decrease in the stem load.

Effects of hydrogen direct-injection angle and charge concentration on gasoline-hydrogen blending lean combustion in a Wankel engine

To analyze the effects of hydrogen charge concentration (HCC) and injection angle (IA) on the lean combustion in a gasoline Wankel engine, the present work implemented a numerical simulation model coupling with the kinetic mechanisms and validated with the experimental data. Results found that with the increase in HCC, the penetration of hydrogen injection is enlarged and the area of the high-speed jet flow is expanded. The jet-flow area for IAs of 45° or 135° is larger than that of 90°. Changing IA could obtain the hydrogen distribution at different regions of the rotor chamber and IA of 90° acquires the smallest hydrogen-rich region. Increasing IA brings about the reduced flame speed substantially; the flame area for IAs of 45° and 90° expands with the increment of HCC whereas the contrary pattern is witnessed at the IA of 135°. Smaller IA leads to the major burning occurring untimely, which resulting in less work delivery of the engine. The hydrogen consumption for IAs of 45° and 90° increases as HCC is ascendant while that for IA of 135° is just the reverse. Variations in the mixture distribution and turbulence are the intrinsic mechanism of how the HCC and IA reflects the combustion progress. As hydrogen is injected with larger HCC and smaller IA, a relatively richer mixture and higher turbulent kinetic energy are distributed close in the spark ignition region. The peak combustion pressure reduces and its corresponding crank position delays with the widened IA at any HCC. Considering the fuel combustion and nitric oxide formation, as hydrogen volume fraction is 3% and IA is 45°, the engine could realize the optimized performance under the computational condition. An efficient combustion performance may be performed in engineering application if the hydrogen IA is in accordance with the rotor rotating direction at lower HCC.

Numerical simulation on combustion process of a hydrogen direct-injection stratified gasoline Wankel engine by synchronous and asynchronous ignition modes

A Wankel engine with hydrogen direct-injection enrichment is recognized as an attractive method to enhance combustion efficiency. In this paper, on the basis of the chemical kinetic mechanisms, a three-dimensional simulation model was established and validated by the measured results. The ignition and combustion processes in a gasoline Wankel engine with hydrogen direct-injection enrichment were implemented for numerical simulation. The influence of twin-spark timing was firstly analyzed by synchronous ignition. Further investigation was then conducted to simulate how to effect the combustion by asynchronous ignition based on the favorable synchronous ignition timing. Results showed that, the average flow velocities were 18.8, 20.7, 23.6, and 25.4 m/s for the spark timings (ST) of 45, 35, 25, and 15°CA BTDC respectively. With retarded ST, the rich equivalence ratio approached to twin-spark plug continually. For synchronous ignition, at a larger advance of ST, the duration between the timing of the vortex dissipation and ST was longer, and the ignition delay was more prolonged. As the ST advanced, the combustion rate was enhanced with the increment in chamber temperature, the reactants (C8H18, C7H16, and H2) consumption and intermediates (H2O2, OH, and CH2O) generation were accelerated, the maximum H2O2 and CH2O decreased whereas the maximum OH increased, and nitrogen oxides (NOx) and carbon monoxide (CO) increased sequentially. For asynchronous ignition, the accelerated flame front was in accordance with the rotating direction of the rotor while the opposite direction was inhibited during the combustion process. An earlier ignition of leading-spark plug (L-plug) or trailing-spark plug (T-plug) provided the higher flame speed and faster H2 consumption, which contributed to the higher in-cylinder pressure, combustion temperature, and NOx and CO production. The preferable ignition and combustion characteristics was realized when the L-plug angle was 25°CA BTDC, and the T-plug angle was 35°CA BTDC. Compared with the favorable synchronous ignition timing, the flame propagation and H2 consumption were expedited, the peak pressure increased by 2.8%, the corresponding crank position advanced by 3°CA and there was no increase in NOx and CO generation. Therefore, it was recommended in engineering applications that the ST of T-plug advanced appropriately while the ST of L-plug remained constant.

Elite handcycling: a qualitative analysis of recumbent handbike configuration for optimal sports performance

Our understanding of handbike configuration is limited, yet it can be a key determinant of performance in handcycling. This study explored how 14 handcycling experts (elite handcyclists, coaches, support staff, and manufacturers) perceived aspects of recumbent handbike configuration to impact upon endurance performance via semi-structured interviews. Optimising the handbike for comfort, stability, and power production was identified as key themes. Comfort and stability were identified to be the foundations of endurance performance and were primarily influenced by the seat, backrest, headrest, and their associated padding. Power production was determined by the relationship between the athletes’ shoulder and abdomen and the trajectories of the handgrips, which were determined by the crank axis position, crank arm length, and handgrip width. Future studies should focus on quantifying the configuration of recumbent handbikes before determining the effects that crank arm length, handgrip width, and crank position have on endurance performance.Practitioner Summary: To gain a greater understanding of the impact of handbike configurations on endurance performance, the perceptions of expert handcyclists were explored qualitatively. Optimising the handbike for comfort and stability, primarily via backrest padding and power production, the position of the shoulders relative to handgrips and crank axis, were critical.

Cylinder Pressure-based Virtual Sensor for Gas State Estimation During Compression Stroke

Abstract The gas state during the compression stroke can vary depending on the operating conditions and cycle-to-cycle variations. In this research, determination of polytropic exponent, trapped mass, and gas temperature are addressed. A golden section search method is applied to cyclic polytropic exponent estimation, and then a statistical filter is employed for cyclic estimation to filter out the estimation noise. A novel iterative-∆p-method is finally presented for the determination of the trapped mass and gas temperature simultaneously during the compression stroke. A sequence of trapped mass estimates and a sequence of gas temperature estimates can be obtained along crank angle position. Experimental validations carried out on a gasoline engine demonstrate the effectiveness of the presented methods.

Effect of dual-spark plug arrangements on ignition and combustion processes of a gasoline rotary engine with hydrogen direct-injection enrichment

A gasoline rotary engine enriched with directly injected hydrogen could be regarded as an appealing option to improve combustion efficiency while reducing emissions. In this paper, a three-dimensional dynamic simulation model coupling with the chemical kinetic mechanisms was established using CONVERGE software and validated by the experimental data. The numerical model was implemented for evaluating the influences of varying duel-spark plug locations on flow field distributions, combustion processes and major emissions formation of a gasoline rotary engine with hydrogen direct injection enrichment. Simulation results showed that, a mainstream flow field formed during the end period of the compression stoke whose direction was identical to the rotor rotating direction. The variation of trailing-spark plug location resulted in slight influence on the mean flow velocity as well as notable impact on hydrogen concentration and turbulent kinetic energy distribution. It was conducive to initial ignition when the local equivalence ratio was intensified near the duel-spark plug on the leading side of the combustion chamber. Higher hydrogen concentration near spark plugs could effectively improve the combustion intensity. The preferable combustion and emission performance were achieved when the duel-spark plug positioned symmetrically with respect to the minor axis. Compared with the scheme of the closest duel-spark plug, the peak pressure increased by 24.4% and corresponding crank position advanced by 9.2°CA. Despite nitric oxides emissions increased slightly, carbon monoxide emission notably reduced by 57.6% versus the scheme of the farthest duel-spark plug. When the leading-spark plug remained constant, the trailing-spark plug arranged on the major axis of cylinder wall and kept an appropriate offset from the minor axis was recommended in engineering applications.

Development of constant output–input force ratio in slider–crank mechanisms

ABSTRACTIn the slider–crank mechanism whereby output piston force is produced against an input force at crank pin centre, the output force varies rapidly when the crank changes its position. For the applications that require a constant piston pushing force as in feeder mechanisms, a method is needed for identifying the parameters to keep output force at a constant value for any crank angle position. Hence in this study, two methods are shown for a slider–crank mechanism operating in horizontal plane. In the first one, a manual control process to generate a constant piston force and the resulting errors are demonstrated. In the second one, identifying the parameters of a mechanical controller for a readily available slider–crank mechanism in an open force control process and the associated error state are shown. Then, an approach to optimize the results of open force control is explained. Finally, the developed methods are generalized for any orientation of the whole slider–crank mechanism. A user friendly interface is developed to transform all the processes into a computer programme. The effectiveness of the methods are numerically illustrated on examples. The results of these examples show that ±4% deviation from the required output force can be obtained pending on the user’s ability while the optimized open force control process provides a maximum error of ±0.4% without any user intervention during operation.

Continuous Lubricant Film Thickness Measurement Between Piston Ring and Cylinder Bore

Measurement of film thickness between piston ring and cylinder bore has been a challenge for decades; laser-induced fluorescence (LIF) method was used by several groups, and promising results are obtained for the investigation of lubricant film transport. In this study, blue light generated by a laser source is transmitted to a beam splitter by means of a fiber optic cable and combined with another fiber optic line, then transmitted to the piston ring and cylinder bore conjunction. The light causes the fluorescence dye present in the lubricant to emit light in a longer wavelength, i.e., green. Reflected light is recollected; blue wavelength components are filtered out using a narrow band pass optical filter, and only components in the florescence wavelength is transmitted to a photomultiplier tube. The photomultiplier produces a voltage proportional to instantaneous lubricant film thickness. Then, the photomultiplier signal is calibrated for lubricant film thickness using a laser textured cylinder bore with known geometries. Additional marks were etched on the liner for calibration. The LIF system is adapted to a piston ring and cylinder bore friction test system simulating engine conditions. Static piston ring and reciprocating liner configuration of the bench test system allow the collection of continuous lubricant film thickness data as a function of crank angle position. The developed system has potential to evaluate new designs, materials, and surface properties in a controlled and repeatable environment.

Hybrid State Space Modeling of a Spark Ignition Engine for Online Fault Diagnosis

In this work, a nonlinear hybrid state space model of a complete spark ignition (SI) gasoline engine system from throttle to muffler is developed using the mass and energy balance equations. It provides within-cycle dynamics of all the engine variables such as temperature, pressure, and mass of individual gas species in the intake manifold (IM), cylinder, and exhaust manifold (EM). The inputs to the model are the same as that commonly exercised by the engine control unit (ECU), and its outputs correspond to available engine sensors. It uses generally known engine parameters, does not require extensive engine maps found in mean value models (MVMs), and requires minimal experimentation for tuning. It is demonstrated that the model is able to capture a variety of engine faults by suitable parameterization. The state space modeling is parsimonious in having the minimum number of integrators in the model by appropriate choice of state. It leads to great computational efficiency due to the possibility of deriving the Jacobian expressions analytically in applications such as on-board state estimation. The model was validated both with data from an industry standard engine simulation and those from an actual engine after relevant modifications. For the test engine, the engine speed and crank angle were extracted from the crank position sensor signal. The model was seen to match the true values of engine variables both in simulation and experiments.