Crank Radius Research Articles

Operation Mechanism Analysis and Parameter Optimization of Bean Impurity-Separation Device for Tiger Nut Harvester

This study aimed to enhance the efficiency of tiger nut combine harvesters by reducing impurity and loss rates during processing. Scholars focused on analyzing the composition and suspension speed of the bean mixture, leading to the development of a wind-screen impurity-removal method. The wind-screen-type bean-separation device was designed with a cross-flow fan, louver screen, frame, and driving mechanism. Theoretical analysis was employed to discuss the motion characteristics and behavior of the sieve body and material, thereby revealing the screening dynamics of tiger nuts and impurities. Factors such as crank radius, crank speed, and fan speed were identified as crucial for optimizing separation performance. Initial single-factor tests helped narrow down the range of influencing factors. Subsequently, a three-factor, three-level Box–Behnken test was conducted with crank radius, crank speed, and fan speed as variables and impurity rate and loss rate as evaluation indexes. This led to the establishment of a multiple regression equation linking these factors to the evaluation indexes. Through response surface analysis and multi-objective optimization using the regression model, the optimal operational parameters for the device were determined: crank radius of 45 mm, crank speed of 497 r/min, and the fan speed of 1100 r/min. Theoretical calculations predicted an impurity rate of 2.42% and a loss rate of 0.51%. Verification tests confirmed these findings, showing an average impurity rate of 2.53% and a loss rate of 0.56%, which met the mechanized harvesting standards for tiger nuts. Overall, this study introduces a novel method and technical framework for effectively separating tiger nuts from impurities, thereby advancing the mechanization of tiger nut harvesting processes.

Design and experimentation of crawler tea harvesting machine

ABSTRACT In this paper, a tracked self-propelled tea harvesting machine is designed. The machine is composed of a tracked chassis, a picking unit, a collection unit, a tea canopy sensing unit, and a cutter height adaptive adjustment unit, The tracked chassis is designed with a narrow width to accommodate the planting mode of Chinese tea plantations. The tea canopy sensing unit and the height adaptive adjustment unit of the cutting platform allow for real-time adjustment of the picking unit’s height based on the tea canopy’s height, improving the tea production rate of fresh leaves. Kinematic analysis of the reciprocating cutter was conducted. To optimize the parameters of the entire machine, a three-factor, three-level quadratic rotational orthogonal test was established, and regression analysis of the test data was performed using Design Expert. The optimized parameters were: machine speed of 3.170 km/h, crank radius of 18.737 mm, average cutter speed of 0.951 m/s, and processable tea rate of 91.38%. To validate the optimization results, field trials were conducted. The findings demonstrated that the processable tea rate was 91.26%, which closely aligned with the optimized results. This study provides a theoretical reference for the tea harvesting machine in tea plantations on hilly slopes.

Kinematics modeling of the gear-based crank mechanism engine regardless of the compressions ratio variations.

In this work, geometric and kinematic modeling of the gear-based crank mechanism engine (GBCM) was performed. To this aim, a mechanical approach based on projective computational methods and mechanism theory laws is applied, to which a parametric study has allowed a conclusion on the geometrical and kinematic behaviors of the moving links. The study concluded that the kinematic quantities at connecting rod head are one-half of those at the piston top head. The extrinsic behavior like the stroke of the connecting rod head is twice the crank radius and the piston kinematic are identical to the conventional engine with the same crankshaft ratio regardless of the compression ratio and any gear wheel radius. Hence, all the extrinsic kinematic properties of a classic crankshaft mechanism of the fixed compression ratio engine remain valid for a gear-based crank mechanism engine and can be used for dynamic calculation purposes.

Performance evaluation of gamma-type Stirling engine using combined Schmidt and mechanical loss model

This paper focuses on the study of gamma-type Stirling engine prototype using a combined Schmidt closed-form and mechanical loss analysis. Not restricted to optimizing the indicated power as classic Schmidt theory is set to, this analysis allows to maximize the shaft power due to the mechanical loss in power transmission. For this purpose, MATLAB code was developed to calculate the indicated and the shaft powers of the engine at different operating parameters. The results showed that shaft power peaks at swept volume ratios smaller than those of indicated power at different values of mechanism effectiveness. Within the range of engine mechanism effectiveness typically between 0.7 and 0.9, it was found that maximum shaft power for this particular engine can be achieved at different optimum values of swept volume ratio between 0.75 and 0.95 and phase angle between 80° and 90°. However, an optimum swept volume ratio was found to be <i>k</i>=0.55 of the same engine size for different scenarios of operation. Also, the developed model can be used as a design tool in the preliminary stage to find the optimum geometry of the engine. The new engine design parameters including the stroke, the crank radius and power piston bore, and engine alteration were presented.

Investigating dynamic characteristics and thermal-lag phenomenon in a thermal-lag engine using a CFD-mechanism dynamics model

Thermal-lag engines (TLE) are external combustion engines with a single piston that offer the potential for reduced maintenance and production costs compared to traditional Stirling engines. Despite these promising prospects, studies on the physical behavior of this engine type remain limited. In this study, three novelties are presented: (1) a novel computational fluid dynamics-mechanism dynamics (CFDMD) model with high complexity for the TLE; (2) an analysis of the work generation in relation to the phase difference between pressure and volume; and (3) an analysis of the thermal-lag phenomenon based on the full spectrum of the phase difference between temperatures and piston position. In the CFDMD model, there are two key components: a computational fluid dynamics (CFD) model that captures the temporal evolution of the three-dimensional thermo-fluid fields and a mechanism dynamics model that solves the transient dynamics of the crank-drive mechanism. The CFDMD model effectively simulates the complex interplay between the thermodynamic behavior of the working gas and the dynamic behavior of the engine mechanism. The study additionally investigates the temporal evolution of the engine speed and examines its dynamic behavior. The influence of parameters, including crank radius, heating temperature, and initial crank angle, on shaft power and brake thermal efficiency is thoroughly explored. To gain a profound understanding of the indicated work generation mechanism and the thermal-lag phenomenon, the discrete Fourier transform provides full spectra of the periodic quantities of interest generated by the CFDMD model. It is found that the numerical average engine speed at different heating temperatures and torques from the CFDMD model is in good agreement with the experimental data, with a maximum difference of 140 rpm. The shaft power decreases from 19.8 to 5.3 W, while brake thermal efficiency increases from 4.5 to 7.7% as the initial crank angle varies from −90° to 90°. The first-oscillation phase differences between pressure and volume are close to 180°, decrease as the heating capacity is raised, and dominate the swelling of the PV diagrams. Only the first harmonic oscillation of the heater temperature exhibits the thermal-lag phenomenon.

CFD ANALYSIS OF SECTOR COMBUSTION SIMULATION IN FOUR STROKE DIRECT INJECTION DIESEL ENGINE

In this article an attempt has been made in cylinder sector combustion CFD simulation of four stroke petrol engines using ANSYS fluent 2019 to obtain very useful results using a modelled engine. In order to improve engine quality, understanding on sector combustion properties in engine cylinder is of major importance because combustion condition significantly influences engine efficiency, Capabilities in providing optimum combustion conditions which include high optimum swirl ratio, and optimum tumble ratio in respective engine can result in enhancement of engine power and comfort, along with reduction of fuel consumption, exhaust emission and noise. The simulation is applied for a geometry with crank radius (55mm), connecting rod length (165mm), Engine speed (1800rpm), which is developed to study the effect combustion inside the cylinder. Piston starts from bottom dead center about 541degrees and the maximum pressure reaches at 716 degrees. The pressure increases from 542 crank angle degree to 716 crank angle degree and reaches its maximum value at 716 crank angle degrees. The Maximum pressure at the end of compression is 63.69Kpa and temperature is 1200K. The maximum penetration length of injection is occurred at crank angle 722 degree is 0.014mm.

Dynamic characteristics analysis of long stroke reciprocating pump combined crank-linkage with rack-pinion mechanism

Drilling pump is the heart of drilling rig, its core structure is crank-linkage mechanism. However, the drilling pump is criticized for its short stroke and high stroke frequency. Aiming at these defects, a long stroke reciprocating (LSR) pump combined the crank-linkage with a rack-pinion mechanism is proposed, and its dynamic and flow characteristics are researched. The results reveal that the stroke of the LSR pump is extended twice when the crank radius stays the same. The stroke frequency and flow pulsation rate are lowered under the same rated power. A new multi-fulcrum crankshaft is designed to extend its fatigue life, and the reaction forces of each fulcrum are solved by simulation. The influence of the fulcrums position on the crankshaft modal frequency is further investigated. The flexible characteristics of the multi-fulcrum crankshaft are studied by rigid-flexible coupled analysis. The results show that more fulcrums can effectively reduce the stress of crankshaft, and the maximum stress of the multi-fulcrum crankshaft is only 178.6 MPa. The modal frequency of the multi-fulcrum crankshaft is increased due to more fulcrums, which proved its stiffness and stability are improved. The fatigue life of the multi-fulcrum crankshaft is predicted to reach 30,000 h by finite element analysis. This study would provide a theoretical basis for further development of the LSR pump.

Investigation of the effect of compression ratio on performance of a beta type Stirling engine with rhombic mechanism byCFDanalysis

AbstractStirling engines take attention due to their high thermal efficiency potential. Many experimental and numerical studies have been performed up to date. Numerical performance analyses of Stirling engines implemented with CFD simulations are classified as 4th order analyses. In the present study, the effect of compression ratio on engine performance of a beta type Stirling engine with rhombic mechanism was investigated by 2D CFD simulation. CFD simulations of the Stirling engine were performed by ANSYS Fluent software. The engine examined by CFD analysis was modeled using the dimensions of an engine manufactured and tested in a previous study, and validation of the CFD simulation was conducted regarding in‐cylinder pressure at 4 bar charge pressure. The crank radius and length of the regenerator zone of the engine were optimized by considering the compression ratio of the engine and engine performance was investigated. Maximum engine performance was obtained at a compression ratio of 2.24 which was ensured by 31.5 mm crank radius and 609.9 mm a length of the regenerator zone. By optimizing the dimensions the engine performance was improved by 99% compared to the base engine configuration. The cyclic work, power, torque, and thermal efficiency were calculated as 62.47 J, 728.93 W, 9.94 Nm, and 37.7% respectively.

Modeling of Thermal-Lag Engine with Validation by Experimental Data

Thermal-lag engines are external combustion engines with a single moving piston. This feature leads to lower manufacturing and maintenance costs than traditional Stirling engines. Although the original concept of thermal-lag engines was invented roughly 35 years ago, the information on thermal-lag engines is still limited. Therefore, this study focuses on thermal-lag engine performance by developing a three-dimensional computational fluid dynamics (CFD) model. The grid independence check and the time step independence check are firstly performed to select the number of elements and size of the time step for simulation. The CFD model is then validated by the experimental data, which were collected by measuring an existing prototype engine. It has been found that the CFD predictions are well fitted to the experimental data over the range of engine speed from 200 to 1600 rpm at temperatures of 1173 or 1273 K. Furthermore, the CFD model predicts that the maximum engine power is 21.1 W while the prototype engine practically generates the highest power of 22.35 W at 1000 rpm and 1273 K. Finally, a further parametric study shows that crank radius, piston diameter, working gas mass, working gas species, and heating temperature significantly affect engine power.

A new method of designing a conversing mechanism of a hinged four-link of a pumping machine

The transforming mechanism of pumping units is a four-link articulated mechanism, made according to symmetrical and asymmetric kinematic schemes. With a symmetrical scheme, the center of rotation of the crank is on a straight line passing through the points corresponding to the extreme positions of the connecting rod and balancer articulation. All other cases correspond to the asymmetric scheme. Currently, in accordance with the existing methodology for designing a converting mechanism of a symmetrical circuit, the kinematic ratios r/k and r/l are used as initial data - the ratio of the crank radius to the length, respectively, of the rear arm of the balance bar and connecting rod. It is considered more preferable and practical to design a mechanism according to predetermined output parameters. As a result, we find that the overall dimensions of the converting mechanism of domestic pumping units of a symmetrical scheme (length by 45…60%, and height - 25…30%) are less than those of foreign pumping units of an asymmetric scheme. The developed technique allows to compare the technical and operational indicators of pumping units made according to various kinematic schemes. Keywords: connecting rod; balancer; cranks; traverse; radius; mechanism.

Influence of formation drilling conditions on the choice of well stimulation method

The paper considers the influence of crank radius change on pumping unit kinematics during the dynamic fluid level control between tubing and casing in order to reduce the string fault rate. To improve the quality of prediction of these factors, the calculation of the movement of the polished rod over time is carried out using the Fourier variable separation method: the product of the balance bar head of a pumping unit defined as the movement of the slider of the pumping mechanism (in a straight line – like the chords of a circle), and the difference of such a chord with the length of the circle section equivalent to the movement of the articulated joint of the balance bar with the connecting rod. As a result, the accuracy of calculations is improved and the solution of the problem is simplified.

TEST OF THE SCREENING AND PARAMETER OPTIMIZATION OF SWING SEPARATION SIEVE IN FIELD OPERATION

The need for clarity regarding the sieving characteristics of the potato-soil mixture, as provided by the swing separating sieve of a potato digger, as well as the derived problems of low potato transportation efficiency, a high potato damage rate and low potato unearthing rate, are the main reasons for this study. Dynamic tracking technology is proposed to collect the motion state of potatoes, during the process of potato and soil separation. Considering the potato conveying speed, potato unearthing rate and potato damage rate as indicators, while the sieving parameters (crank rotational speed, sieve inclination, crank radius and swing direction angle) are the influencing factors, an orthogonal regression test is carried out, where the response surface is used to analyze each factor, its influence on the screening index, and to optimize it accordingly. The test results show that there is a linear relationship between the screening parameters and indexes, with each parameter showing different contribution rates to the screening indexes. The best parameter combination is the crank rotational speed of 190 r /min, sieve inclination of 9.7°, crank radius of 40 mm and swing direction angle of 18.8°. The corresponding potato conveying speed, unearthing rate and damage rate is 0.713 m/s, 98.7% and 3.224%, respectively. After optimization, the potato conveying speed is 1.43 times higher, the unearthing rate is increased by 2.5% and the damage rate is reduced by 60%. The research results can provide theoretical support to the structural design of potato diggers.

НОВАЯ МЕТОДИКА ПРОЕКТИРОВАНИЯ ПРЕОБРАЗУЮЩЕГО МЕХАНИЗМА СТАНКОВ-КАЧАЛОК

The relevance of the research is caused by the need to ensure more efficient operation of the kinematic scheme of the pumping unit. The solution to this problem will improve the operation of the kinematic scheme from the point of view of the loads arising in it and reduce the metal consumption of the surface drive of the sucker rod pump during its design. The main aim of the research is to develop and propose a methodology for designing pumping unit during its production and manufacture. Objects. The converting mechanism of the pumping units is a hinged four-link mechanism made according to symmetrical and asymmetrical kinematic schemes. With a symmetrical scheme, the center of rotation of the crank is on a straight line passing through the points corresponding to the extreme positions of the articulation of the connecting rod and the balance bar. All other cases correspond to an unbalanced scheme. At present, in accordance with the existing design technique of the symmetrical circuit converting mechanism, the kinematic ratios r/K and r/l are used as the initial data – the ratio of the crank radius to the length of the rear arm of the balancer and the connecting rod, respectively. The object of research is a hinge mechanism that converts the rotational motion of an electric motor into a reciprocating motion of the suspension point of the rods. Methods. The technique that allows you to design a mechanism according to predetermined output parameters is more preferable and practical. At the same time, it is recommended to use parameters that directly determine both the type of the kinematic diagram of the converting mechanism and its overall dimensions. It should be noted that not all theoretically real mechanisms can be practically feasible. Therefore, the real area of ​​angles ψ is somewhat narrower than the theoretical real area and should be determined taking into account the design features of the mechanism (for example, in an extremely close position to the body, the traverse should not touch the gearbox housing, the height of the mechanism should be such that in the lower position the suspension of the wellhead rod does not touch the wellhead oil seal, etc.). For convenience of using the proposed method, it is advisable to present the sought values ​​in the given form (in fractions of the stroke length). Results. According to the formulas obtained, using the data from catalogs of different companies, the reduced values ​​of the kinematic parameters of the converting mechanisms of various kinematic schemes are calculated. As a result, we find that the overall dimensions of the converting mechanism of domestic pumping units of a symmetrical scheme (length by 45 ... 60 %, and height by 25 ... 30 %) are smaller than those of foreign pumping units of an asymmetrical scheme. The developed technique makes it possible to compare the technical and operational indicators of pumping units made according to various kinematic schemes. The proposed technique with the optimal position function, at which the dynamic loads on the drive are minimal, the efficiency of the downhole sucker rod pump is maximal, makes it possible to reduce the metal consumption of the pumping unit during its design.

Investigations into Balancing Peak-to-Average Power Ratio and Mean Power Extraction for a Two-Body Point-Absorber Wave Energy Converter

The power harnessed by wave energy converters (WECs) in oceans is highly variable and, therefore, has a high peak-to-average power (PTAP) ratio. To minimize the cost of a WEC power take off (PTO) system, it is desirable to reduce the PTAP ratio while maximizing the mean power extracted by WECs. The important issue of how PTAP ratio reduction measures (such as adding an inertia element) can affect the mean power extracted in a reference model has not been thoroughly addressed in the literature. To investigate this correlation, this study focuses on the integration of the U.S. Department of Energy’s Reference Model 3, a two-body point absorber, with a slider-crank WEC for linear-to-rotational conversion. In the first phase of this study, a full-scale numerical model was developed that predicts how PTO system parameters, along with an advanced control algorithm, can potentially affect the proposed WEC’s PTAP ratio as well as the mean power extracted. In the second phase, an appropriate scaled-down model was developed, and extracted power results were successfully validated against the full-scale model. Finally, numerical and hardware-in-the-loop (HIL) simulations based on the scaled-down model were designed and conducted to optimize or make trade-offs between the operational performance and PTAP ratio. The initial results with numerical and HIL simulations reveal that gear ratio, crank radius, and generator parameters substantially impact the PTAP ratio and mean power extracted.

Balancing of the moments of the VR-5 type engine taking into account the desaxial and the cylinder camber angle

Recently, V-engines with a small angle of camber are more widely used as power units for passenger cars, especially because of the reduced engine length, and the transverse dimensions are almost the same as in-line ones. All this leads to an increase in overall engine power. However, due to the small camber angle between the parallel rows of cylinders, the intersection of the cylinders in their lower part may occur. To prevent the latter, significant multidirectional desaxial is used. Moreover, the calculation of the dynamics of similar engines introduces a number of features, including balancing the inertia forces and their moments from the reciprocating moving and rotating masses. The article discusses the balancing of 5-cylinder four-stroke VR type engines with desaxial crank mechanism and uniform flash alternation. The formulas allowing to find and analyze moments of the inertia forces of the reciprocating and rotating masses arising in VR-5 engines are given by the given value of the cylinder camber angle, the ratio of the crank radius to the connecting rod length and the relative displacement of the cylinder axis. A method of balancing the moments of inertia forces of the reciprocating and rotating masses is proposed and the results of the presented dynamic study of a VR-5 engine using analytical, software and graph-analytical methods.

Steady State Unbalance Response Analysis of Internal Combustion Engine Crankshaft Based on Torsional Vibration

Crankshaft is one of the main moving parts in internal combustion engine. The instantaneous gas pressure and effective crank radius of each cylinder of the engine and the ignition interval angle of each cylinder make the torque of each crank change constantly, which causes the torsional vibration of the crankshaft. Based on the lumped parameter model, the transfer matrix method is used to analyze the steady-state unbalance response of internal combustion engine crankshaft, which has a certain reference value for mastering the influence of torsional vibration on the working state and strength safety of crankshaft.

Analysis of Design Parameters of a Novel Modified Reciprocating Mechanism

In this study, displacement, velocity and acceleration equations were obtained for the mechanism created by modifying the long-stroke reciprocating mechanism. Thus, a novel mechanism has been created. In addition, the effects of the design parameters were examined and the results obtained were compared with the conventional crank-connecting rod mechanism. While the crank radius (r) and connecting rod length (L), which are the main design parameters of the conventional crank-connecting rod mechanism, are fixed, the design parameters of the novel mechanism are changed and the effects of these design parameters on the velocity and acceleration characteristics are examined. For the novel mechanism, the ratio of the inner gear radius to the pinion gear radius (r2/r1=k) and the ratio of the output gear radius to the pinion gear radius (r0/r1=m) are determined as the basic design parameters. Accordingly, by decreasing k and increasing m, it was seen that the connecting rod angle, mean piston velocity, and mean piston acceleration were decreased. The correct choice of k and m shows that the novel mecha-nism can be made more advantageous compared to the conventional crank-connecting rod mechanism. The results are predicted to be promising for engine designers.

Уравновешивание моментов двигателя VR5 с учетом дезаксажа и угла развала цилиндров

Automobile piston engines with a desaxial crank mechanism are characterized by increased vibration activity associated with a cyclic change in the pressure of the working fluid in the cylinders and inertial forces associated with the reciprocating and rotational movement of the crank mechanism moving masses. Properties reflecting the consumer properties of the engine, including acoustic characteristics, are largely determined by the level of vibration of the structural elements of the desaxial crank mechanism and, first of all, by the balance of inertial forces during operation. The article discusses balancing of five-cylinder four-stroke VR type engines with a desaxial crank mechanism and uniform flash alternation. The authors introduce formulas that can be used to determine and analyze moments of the inertia forces of the reciprocating and rotating masses arising in VR5 engines at the set values of the cylinder camber angle, the ratio of the crank radius to the connecting rod length and the relative displacement of the cylinder axis. A method of balancing the moments of inertia forces of the reciprocating and rotating masses is proposed.

Kinematic and thermodynamic operational analysis of rhombic-drive Stirling engine prototype

This operational analysis is aimed for the next development of rhombic-drive beta-configuration Stirling engine prototype. The kinematic analysis focused on the adjustment of crank radius and connecting rod length, for achieving optimum phase angle setting and suitable eccentricity ratio based on geometrical constraints. The isothermal thermodynamic analysis is carried out to predict the engine performance between the baseline and proposed design parameters. The reciprocating displacement of moving pistons, volumetric displacement, cyclic pressure, energy produced and thermal efficiency are derived and solved. The results show that the reduction of crank radius increases the eccentricity ratio, while both reduction of connecting rod length and crank radius increase the phase angle setting. It is found that as the phase angle setting increase, the engine power output and thermal efficiency increase. The magnitudes of engine power and thermal efficiency may be elevated by modifying the geometrical design and operating condition.

Separating neural influences from peripheral mechanics: the speed-curvature relation in mechanically constrained actions.

While the study of unconstrained movements has revealed important features of neural control, generalizing those insights to more sophisticated object manipulation is challenging. Humans excel at physical interaction with objects, even when those objects introduce complex dynamics and kinematic constraints. This study examined humans turning a horizontal planar crank (radius 10.29 cm) at their preferred and three instructed speeds (with visual feedback), both in clockwise and counterclockwise directions. To explore the role of neuromechanical dynamics, the instructed speeds covered a wide range: fast (near the limits of performance), medium (near preferred speed), and very slow (rendering dynamic effects negligible). Because kinematically constrained movements involve significant physical interaction, disentangling neural control from the influences of biomechanics presents a challenge. To address it, we modeled the interactive dynamics to "subtract off" peripheral biomechanics from observed force and kinematic data, thereby estimating aspects of underlying neural action that may be expressed in terms of motion. We demonstrate the value of this method: remarkably, an approximately elliptical path emerged, and speed minima coincided with curvature maxima, similar to what is seen in unconstrained movements, even though the hand moved at nearly constant speed along a constant-curvature path. These findings suggest that the neural controller takes advantage of peripheral biomechanics to simplify physical interaction. As a result, patterns seen in unconstrained movements persist even when physical interaction prevents their expression in hand kinematics. The reemergence of a speed-curvature relation indicates that it is due, at least in part, to neural processes that emphasize smoothness and predictability.NEW & NOTEWORTHY Physically interacting with kinematic constraints is commonplace in everyday actions. We report a study of humans turning a crank, a circular constraint that imposes constant hand path curvature and hence should suppress variations of hand speed due to the power-law speed-curvature relation widely reported for unconstrained motions. Remarkably, we found that, when peripheral biomechanical factors are removed, a speed-curvature relation reemerges, indicating that it is, at least in part, of neural origin.