Crankshaft Engine Research Articles

Оценка технической возможности достижения одинакового хода поршней в кривошипно-шатунном механизме с прицепными шатунами

The article presents the technical capabilities for achieving the specified operating characteristics of engine components and parts taking into account the geometric characteristics of the crank mechanism (crank mechanism). It also presents the assessment and achievements of the required level of strength parameters of some structural elements of the main connecting rod and the entire mechanism as a whole. Making changes to a proven design and established production is a complex and multifactorial task. It is necessary to make changes that would minimize production and technological losses. Besides, they must fit harmoniously into existing technology and production capabilities ensuring the fulfillment of new technical requirements and characteristics. When solving the problem of ensuring the same piston stroke for a V-2 engine, the analysis of the design documentation showed that in addition to making changes to the design of the crank mechanism, it is necessary to make changes to other engine parts. The need for these changes was determined by the method of “scrolling” the assembly of crankshaft parts in the volume of the engine crankcase using 3D modeling programs for parts and checking their performance. The results of assessing the kinematics of the crankshaft engine of V-2 type engines proved that in addition to changing the design of the main connecting rod, it is necessary to perform additional processing of the axial stiffener rib of the upper half of the crankcase, as well as to make changes to the design of the trailing connecting rod in order to eliminate contact with the cylinder liner and, possibly, the liner itself. However, changes in the engine design will entail significant changes in the technological process of its manufacture. Obviously, these changes should be minimal. In order to preserve the engine design, it is necessary to make some significant changes. They can affect significant production and technological changes, which in conditions of mass production require fairly strong theoretical and practical justification. Therefore, when implementing these technical solutions, it was necessary to perform calculation and kinematic analysis based on 3D modeling and logical analysis, excluding disruption of engine operation. In addition, to assess the load on the lower head of the connecting rod, a hydrodynamic calculation was performed. The results also include the hydromechanical characteristics of a complexly loaded bearing and a diagram of the hydrodynamic pressures acting in a thin lubricant layer

Ways to improve the efficiency of autonomous heaters and preheating systems of automobile engines

The article analyzes autonomous heaters and preheating systems for automobile engines, possible ways to improve their efficiency and safety, through the use of devices for heating crankshaft bearings and engine oil heaters. Keywords: technical readiness of the car, pre-start liquid heater, heating system, heating capacity of the heater, the moment of resistance to turning the crankshaft, thermal preparation of engine oil

Performance Characteristics of a Small Poppet Valve Crankshaft Engine in Free-Piston Engine Mode

The free-piston engine generator (FPEG) provides a novel method for electrical power generation in the range extender and hybrid electric vehicle application. In this paper, one-dimensional (1D) numerical simulations of a two-stroke poppet valve in crankshaft engine (CSE) and free-piston engine (FPE) modes are presented to illuminate the potential performance gain of a two-stroke poppet valve engine for free-piston engine generator application. The 1D numerical simulation for crankshaft and free-piston engine models focuses on the two-stroke engine performance response. Both models were subjected to variations of ignition and valve timings. The impact of lambda on engine performance was obtained. Finally, a single speed of 3000 rpm was chosen for detail performance behaviour of the free-piston engine model response. The results have shown that the CSE model has demonstrated traditional performance behaviour against ignition timing variation. In addition, FPE model performance is highly affected by both intake and exhaust valve timings as compared to the CSE model. Furthermore, CSE is superior to FPE across lambda variations for BSFC, brake thermal efficiency, brake power and bmep. These models have successfully portrayed realistic engine performance response as presented in the lambda variations simulation. When simulated at an intended operating speed of 50 Hz, the FPE model has shown poorer performance. The bmep and brake power of FPE model dropped by 3%, brake thermal efficiency dropped by 26%, and BSFC increased by 21%. This lower performance is attributed by 30% reduction in piston velocity suffers in FPE, which contributed to 13% reduction in peak cylinder pressure. Ignition delays promote better FPE performance which is able to match the CSE model. In conclusion, this paper has demonstrated the performance behaviour of a two-stroke free-piston engine model based on the baseline crankshaft engine model.

Comparative analysis on friction characteristics between free-piston engine generator and traditional crankshaft engine

Compared with traditional crankshaft engines (TCEs), free-piston engine generators (FPEGs) present many potential advantages due to the abandonment of crankshaft mechanism. The friction loss in FPEGs is considered to be lower than that in TCE. However, few studies have calculated and analyzed the friction differences between them in any great detail. This paper presents an equivalent design of two-stroke TCE based on an existing FPEG prototype size, and then determines the main friction components of their prototypes. The comprehensive simulation models of FPEG and TCE are established in MATLAB/Simulink. Following this, the friction models and lubrication characteristics of each part in FPEG and TCE are described and compared based on the fundamental lubrication theory. The simulation results show good agreement with the experimental data for both the cold start and combustion power generation. And the overall error between them is less than 5%, indicating that the simulation model is reliable and can predict the prototype performance. Moreover, the effects of lubricating oil grade, temperature and operating frequency on the friction performance of FPEG are also investigated. Results show that the piston assembly friction power is less powerful in FPEG (118.3 W) than that in TCE (142.1 W), while the friction power of piston rings is slightly more powerful in FPEG than TCE. The total mean friction power is significantly lower in FPEG than that in TCE, with the proportion of total mean friction power to the indicated power being 11% in TCE and 6.7% in FPEG. This distribution of friction power indicates that when concerning friction loss, FPEG has an advantage over TCE. The piston ring friction power increases with an increase in lubricating oil temperature and operating frequency, and decreases with an increase in lubricating oil viscosity. The proportion of mean friction power to the indicated power shows a decreasing trend as the viscosity and operating frequency increase, and an increasing trend as the lubricating oil temperature increases.

Numerical comparison of HCCI combustion mode between a free piston linear engine and traditional crankshaft engine

The free piston linear engine (FPLE) eliminates the crankshaft components and supports variable compression ratio operation. This characteristic makes it as one of the most appropriate choices to adopt HCCI combustion mode. This work aims to reveal the preliminary characteristics of HCCI combustion in FPLE and compare it with traditional crankshaft engines (TCE). The HCCI combustion model of TCE and FPLE was established by using a chemical kinetic reaction mechanism, and it then was numerically calculated to obtain the combustion and emission performance. The results indicate that the typical two-stage reaction characteristic of HCCI combustion also occur in the FPLE. Although the final cumulative heat release of the two types of engines is approximately the same, the low-temperature reaction stage of FPLE comes later, which also leads to the lag of its high-temperature reaction stage. In addition, the TCE features with earlier heat release rate, higher peak pressure and temperature, and longer duration of high temperature, which are beneficial to promote the reaction of soot, thereby slightly reducing soot emissions, but also increasing NO emissions.

Special aspects of the test of ATV equipped with the electronic engine management system Continental M3C on a dynamometer test bench

In this article the problems of taking characteristics of the power plant of BRP Can-Am Outlander max 570 at its loading on a dynamometer test bench DynaPack are considered. The possibilities of using input and output electrical signals of sensors and actuators of the electronic engine management system Continental M3C, including the use of third-party electronic engine management unit M74CAN cars VAZ. The schematic solutions for obtaining the value of the engine crankshaft speed of the ATV by the standard software of the DynaPack dynamometric stand are proposed. Based on the analysis of the developed circuit solutions, as well as the features of loading, power plant in general, and the engine in particular, on the dynamometer test bench DynaPack decided to use the fuel injector control signals to determine the speed of the crankshaft engine. To increase the stability of the results of the series of experiments, a method of monitoring the position of the engine throttle valve was proposed. In conclusion, the speed characteristics of the BRP Can-Am Outlander max 570 quad bike power plant at various levels of opening the throttle valve are shown.

Feasibility of Multiple Piston Motion Control Approaches in a Free Piston Engine Generator

<div class="section abstract"><div class="htmlview paragraph">The control and design optimization of a Free Piston Engine Generator (FPEG) has been found to be difficult as each independent variable changes the piston dynamics with respect to time. These dynamics, in turn, alter the generator and engine response to other governing variables. As a result, the FPEG system requires an energy balance control algorithm such that the cumulative energy delivered by the engine is equal to the cumulative energy taken by the generator for stable operation. The main objective of this control algorithm is to match the power generated by the engine to the power demanded by the generator. In a conventional crankshaft engine, this energy balance control is similar to the use of a governor and a flywheel to control the rotational speed. In general, if the generator consumes more energy in a cycle than the engine provides, the system moves towards a stall. If the generator consumes less energy, then the effective stroke, compression ratio and maximum translator velocity must rise steadily from cycle-to-cycle until the heat transfer losses stop the increase. Moreover, when stiff springs are added to the FPEG system, the dynamics becomes more sinusoidal and more consistent with increasing spring stiffness. To understand the behavior of proposed control and cycle-to-cycle variations, a comprehensive FPEG numerical model with a 1 kW target electric power was developed in MATLAB<sup>®</sup>/Simulink. An FPEG system corresponding to that numerical model has been operated in the laboratory. This MATLAB<sup>®</sup>/Simulink numerical model has been used to examine the sensitivity of FPEG dynamics and performance parameters to the changes in design and operating inputs. A difficulty during the modeling is associated with the cycle-to-cycle energy balance, and this difficulty is also reflected in the real-world FPEG control. Therefore, the authors have devised a control strategy similar to the real world intended control methodology. In this numerical model, two different feedback control methodologies were implemented and investigated. These control methodologies were applied to regulate the generator load with selected control or input variables, namely peak pressure, mid-stroke piston velocity, trapped compression ratio and dead center set points. The controllers with optimized coefficients demonstrated the feasibility of energy balance management during the transient operation. Based on the simulation results, the controllers with compression ratio, peak pressure and dead center clearance set points as control variables demonstrated stable FPEG operation whereas the mid-stroke velocity failed to achieve the steady-state operation due to deviation in the piston dynamics. The simulation results from this study will be used as the pathway for improving and optimizing the experimental FPEG design.</div></div>

Measurement of the crankshaft seals friction losses in a modern passenger car diesel engine

This paper presents results of experimental investigations on the friction losses of the crankshaft radial lip seals of a modern four-cylinder diesel engine for passenger car applications. A two stage strip-test has been conducted on a motored engine test bed to obtain the friction torque of the radial lip seals. For the experimental investigations with the crankshaft seals removed from the engine, a special sealing apparatus has been designed and built. A wide range of tests have been performed covering the full speed range of the engine at lubricant temperatures of 70 ℃, 90 ℃, and 110 ℃. The results show a dependency on crankshaft speed and engine media supply temperature but also revealed the presence of constant plateaus of friction torque over engine speed.

Numerical evaluation of pollutant emissions of a two-stroke linear engine.

Combustion engines bring a lot of pollution products to human living environment. This study introduced a green engine called free-piston linear engine (FPLE), and performed an evaluation on the pollutant emissions of a diesel FPLE by comparison with a corresponding conventional crankshaft engine (CCE). The combustion reaction and pollutant formation were described by a comprehensive model which considers the special operation mechanism of the FPLE. The effect of dynamic and fuel quantity on the unclean combustion products of the FPLE and the CCE was compared. Results indicate that in the case of the fuel quantity of 7.1mg condition, the pollutant forming in the FPLE is generally later than that in CCE because of the higher speed of FPLE around the reverse point of stroke, and a significant advantage in nitric oxide (NO) emission is found for the FPLE, although it emits more carbon monoxide (CO) and soot. Moreover, compared with the CCE, the FPLE is cleaner in lean fuel conditions because the NO production of the FPLE is only half of that of the CCE, and that of other pollutants is almost at the same level. However, in heavy fuel conditions, the FPLE shows a disadvantage in CO and soot emission due to the serious afterburning effect and poor oxygen environment in some local areas, although its NO production is still lower than that of the CCE.

Parametric Investigation of Combustion and Heat Transfer Characteristics of Oscillating Linear Engine Alternator

An Oscillating Linear Engine Alternator (OLEA) has the potential to overcome the thermal, mechanical, and combustion inadequacies encountered by the conventional slider-crank engines. The linear engines convert the reciprocating piston motion into electricity, thereby eliminating needless crankshaft linkages and rotational motion. As the dead center positions are not explicitly identified unlike crankshaft engines, the linear engine exhibits different stroke and compression ratio every cycle and should manage the unfavorable events like misfire, rapid load changes, and overfueling without the energy storage of a flywheel. Further, the apparatus control and management strategy is difficult for OLEA when compared to conventional engines and depends on the combustion event influencing the translator dynamics. In this research paper, the MATLAB®/Simulink numerical model of a single cylinder, mechanical spring assisted, 2-stroke natural gas fueled, spark-ignited OLEA was investigated to enhance the perception of the coupled system. The effect of combustion and heat transfer characteristics on translator dynamics and performance of OLEA were analyzed by using Wiebe form factors, combustion duration, and heat transfer correlations. Variation in the Wiebe form factors revealed interesting insights into the translator dynamics and in-cylinder thermodynamics of a coupled system. High translator velocity, acceleration, and higher heat transfer rate were favored by low combustion duration.

A study and comparison of frictional losses in free-piston engine and crankshaft engines

Friction work in free-piston engines is expected to be lower than in crankshaft engines due to the elimination of the crank mechanism. In this paper, friction mechanisms were reviewed and compared between a free-piston and crankshaft engine of similar size. The main friction mechanisms were identified to be the piston assembly including piston rings and piston skirt, valve train system, the crank and bearing system for the CSE, and the linear electric generator for the FPE. The frictional loss of each friction mechanism was estimated and discussed. A Stribeck diagram was used to simulate the piston ring friction during hydrodynamic lubrication, mixed lubrication, and boundary condition. It is found that the FPE doesn’t show advantage on piston ring friction force over the CSE, and the frictional loss from the piston ring is even higher. While the elimination of the crankshaft system reduces the frictional loss of the FPE, and the total friction loss of the FPE is nearly half of the CSE.

Plotting and Determination of Nominal Stresses in the Сrankshaft Components of V Configuration Engine with Offset Rod Bearing Journals

Currently, a great number of large vehicle engines, especially diesel ones, have a V-shaped configuration layout. For six-cylinder and eight-cylinder V-engines, to simplify a processing technology of the block-crankcases, in the section manufacturers often use the 90 ° angle, which is the most prevalent angle for the V8 engine. However, in this case, an even firing cycle in the cylinders is not provided for the V6 layout. This leads to significant vibrations, especially at idle and requires for a more massive flywheel. Designers face the challenge to provide the even firing cycle in the cylinders. To solve this problem are often used the crankshaft designs, which have the offset rod journals. However, it leads to the manufacturing complexity of the shaft, and also to the need to use the special methods of calculation. There are no direct calculation methods for the crankshafts of this design. The paper proposes a technique to define the nominal stresses in the crankshaft of this design. To consider the shaft is used a split-type design. The paper presents a schematic diagram of the crankshaft loading, and on its basis describes equations of the moments for each section. A special attention is drawn to the new constructive element, i.e. an intermediate cheek. For clarity, the diagrams of moments in two mutually perpendicular planes are built. It is worth noting that the paper also proposes a technique from transition from the global to the local coordinate system when considering the moments in the crankshaft elements. Further, there are the appropriate expressions to determine the nominal stresses. This is one of the main desired values in calculating the crankshaft endurance. The developed technique in the particular case allows the calculation of crankshaft engine models that can be subsumed under the advantages. In the future the proposed technique is expected to be a basis for creating a software complex. The complex objective is expected to be capable to calculate the endurance of the crankshafts with offset connecting rod journals in a wide range of the main design variables, and, as already mentioned, calculate the shaft endurance of the reciprocating engine.

Tribological characteristics of piston rings in a single-piston hydraulic free-piston engine

PurposeA free-piston engine (FPE) is an unconventional engine that abandons the crank system. This paper aims to focus on a numerical simulation for the lubricating characteristics of piston rings in a single-piston hydraulic free-piston engine (HFPE).Design/methodology/approachA time-based numerical simulation program was built using Matlab to define the piston motion of the new engine. And a lubrication mode of piston rings was built which is based on the gas flow equation, hydrodynamic lubrication equation and the asperity contact equation. The piston motion and the lubrication model are coupled, and then the finite difference method is used to obtain the piston rings lubrication performances of the FPE. Meanwhile, the lubrication characteristics of the new engine were compared with those of a corresponding conventional crankshaft-driven engine.FindingsThe study results indicate that compared with the traditional engine, the expansion stroke of the HFPE is longer, and the compression stroke is shorter. Lubrication oil film of the new engine is thicker than the traditional engine during the initial stage of compression stroke and the final stage of the power stroke. The average friction force and power of the hydraulic free piston engine are slightly lower than those of the traditional engine, but the peak friction power of the FPE is significantly greater than that of the traditional engine. With an increase in load, the friction loss power and friction loss efficiency decrease, and with a decrease in equivalence ratio, the friction power loss reduces, but the friction loss efficiency decreases first and then increases.Research limitations/implicationsIn this paper, only qualitative analysis was performed on the tribological difference between conventional crankshaft engine and HFPE, instead of a quantitative one.Practical implicationsThis paper contributes to the tribological design method of HFPE.Social implicationsNo social implications are available now, as the HFPE is under the development phase. However, the authors are positive that their work will be commercialized in the near future.Originality/valueThe main originality of the paper can be introduced as follows: the lubrication and friction characteristics of the new engine (HFPE) were investigated and revealed, which have not been studied before; the effect of the HFPE’s special piston motion on the tribological characteristics was considered in the lubrication simulation. The results show that compared with the traditional crankshaft engine, the new engine shows a different lubrication performance because of its free piston motion.

The closed-cycle model numerical analysis of the impact of crank mechanism design on engine efficiency

The research presents a review and comparison of different engine constructions. Investigated engines included crankshaft engines, barrel engine, opposed-piston engines and theoretical models to present possible variations of piston motion curves. The work comprises also detailed description of a numerical piston engine model which was created to determine the impact of the cycle parameters including described different piston motion curves on the engine efficiency. Developed model was equipped with Wiebe function to reflect a heat release during combustion event and Woschini’s correlation to simulate heat transfer between the gas and engine components.Various scenarios of selected engine constructions and different working conditions have been simulated and compared. Based on the results it was possible to determine the impact of different piston motion curves on the engine cycle process and present potential efficiency benefits.

Environmental Performance Improvement in Gasoline Engines with External Mixture Formation

The results of experimental and theoretical research that indicate the improvement of the environmental performance of the petrol vehicle of class M1 are shown. The fuel and air channels of engine are equipped with permanent magnets. Studies were carried out at slow and fast idling of a crankshaft engine. Permanent magnets are installed in such a way that the magnetic field lines pass through the fuel and air in the perpendicular plane relative to the direction of flow of the material. It creates a magnetic flux of different configurations and intensity. As a result of such influence, the composition of the exhaust gas is changed. The toxic components are reduced in such exhaust gases. The results of experimental studies were approximated by polynomials of the second degree. As a result, the optimal combination of flow on the criterion of a minimum total toxicity was identified.

Free piston engine generator: Technology review and an experimental evaluation with hydrogen fuel

Free piston engine generators which utilize a free piston engine and a linear generator are under investigation by a number of research groups around the world. Free piston engines give power output in a more efficient way when compared to conventional crankshaft engines, because the former do not have a crank mechanism which brings about additional mechanical loss. However, for the reliable and stable operation of the free piston engine generators, it is required to have a viable control system to address the uncertainty of piston motion. In this paper, most of the successful free piston engine generator developments were reviewed and a recent experimental result on a prototype free piston system was also presented with regard to engine performance with different mixture preparation strategies.

Tribological Characteristics of Piston Ring in a Free-piston Engine for Linear Generator

This research aims to obtain the piston ring tribological characteristics of a free-piston engine. Mathematical models of piston ring seal and lubrication were established based on thermodynamic equation and hydrodynamic lubrication equation. The lubrication performances of the piston ring were simulated; the effects of the piston motion to piston ring lubrication process were analyzed compared with a corresponding conventional engine. Results show that seal working time of free-piston ring is longer than conventional engine's during a cycle time, but the leakage loss is lower. Besides, the oil film thickness of piston ring in free-piston engine is thinner than that of crankshaft engine just around TDC, but other position is thicker. Moreover friction forces and friction work of piston ring in two engines are almost equivalent, but the peak friction power of free-piston engine is larger than crankshaft engine.

A simplified coupled crankshaft–engine block model

Modern highly loaded crankshafts and bearing improvement requires an accurate knowledge of the acting forces. This information is now provided by quick and robust design tools based on simplified coupled engine block–crankshaft models. In this paper, a model based on beam theory is proposed. Several considerations are addressed. Among these considerations are bearing misalignments, crankshaft bending stiffness, clearance, hydrodynamic sustention and bearing deformation stiffness. The model substitutes efficiently engine simulation in crankshaft and bearing preliminary design.

An experimental study of the cycle stability of hydraulic free-piston engines

The piston motion of hydraulic free-piston engine (HFPE) without being restricted as that of conventional crankshaft engine (CE), leads to the cyclic variations, which raises concerns over engine cycle stability. It is therefore necessary to investigate the cycle-to-cycle variations in the piston dynamics and cycle stability of HFPEs. For this purpose, we conducted and evaluated an experimental study of a prototype HFPE. The experimental results indicate that the HFPE was in steady state when it ran at the maximum range of the cyclic variations in the piston dynamic parameters. In addition, variations in the top dead center (TDC) position, bottom dead center (BDC) position, starting piston position and compression ratio were investigated. In this prototype, the maximum variation in the TDC position relative to the total stroke was 1.2%; the starting position of the piston oscillated between 11 and 19 mm, the maximum variation relative to the total stroke was 2.9%; the BDC variation ranged from 4.5 to 13 mm; and the maximum relative variation in the BDC position to the total stroke was 2.7%.

Dynamic model of a two-cylinder four-stroke internal combustion engine and vibration treatment

Engine vibrations of large amplitude are caused by inertial effects of the piston–crankshaft mechanism and gas forces, and are transmitted to the chassis of a vehicle in the form of periodically varying forces through the engine mounts. Both the engine vibrations and mount forces may be minimized by designing proper engine components and mounts, which requires a dynamic simulation of the engine. In this study, a three degree of freedom dynamic model, enabling the simultaneous treatment of the piston–crankshaft mechanism and engine block, was devised for a two-cylinder four-stroke engine. Periodic and temporary variations of crankshaft speed, the variation of torque and power with speed, torsional and translational vibrations of the engine block, and the variation of mount forces with respect to the damping and stiffness coefficients of the mounts were studied. The torsional and translational vibrations of the engine block were found to be mainly affected by the combustion gas force and inertia force of the reciprocating masses, respectively. A simple relation has been obtained to determine the position and mass of counterweights used for eliminating the vertical vibration of the block.