Browse Topic: Connecting rods
To solve the poor mobility of traditional camping vehicle chassis in complex terrains and confined spaces, this paper proposes an underactuated omnidirectional mobile chassis for outdoor camping vehicles. The chassis adopts a coupled commutation mechanism (double-crank elastic special-shaped connecting rods cross sliders), allowing each wheel to realize two motion modes (omnidirectional translation, in-situ rotation) with just one drive motor, reducing system complexity and cost. A control system based on the RoboMaster Development Board C Type integrates PID angle-loop control and motor speed-current dual closed-loop control for motion stability. Kinematic models for these two modes are established to derive the wheel parameter-chassis motion relationship. MATLAB R2023b-ADAMS 2024 co-simulations show the chassis maintains attitude stability under S-shaped curve, circular curve, and in-situ rotation; Qualisys 3D motion capture experiments confirm its stable attitude in omnidirectional movement.
Condition-based monitoring (CBM) has emerged as a transformative approach in predictive maintenance, enabling the proactive identification of potential component failures. It offers numerous advantages like Cost Savings, Increased Equipment Lifespan, RCA of failed parts, Optimized Resource Utilization, Reduced Disruptions, Enhanced Reliability and Safety and many more making it a vital approach for effective maintenance and operational efficiency. This paper presents a comprehensive methodology for monitoring and analyzing vibration trends to predict and prevent the breakdown of critical components in IC Engine in its testing phase. The good part here is that this methodology is not just limited to IC Engine but can be applied across wide range of industries and mechanical systems as from the literature and past vibration data, it was observed that before any such failure engine vibration increases. If the engine is stopped at that moment, it can be preserved, allowing for further investigation to be conducted. During the engine reliability development process, failures in the crank train and valve train can result in damage to multiple components, making it challenging to analyze the sequence of failure and identify the initial cause and root problem. By employing advanced vibration analysis techniques, the study aims to detect anomalies indicative of wear, misalignment, or other precursors to failure. This research contributes to the growing body of knowledge in CBM, offering a scalable and adaptable framework for implementing vibration-based predictive maintenance across diverse industrial applications. The proposed methodology not only enhances reliability but also supports sustainable maintenance practices by minimizing resource wastage and ensuring timely interventions.
In this article we examine the behavior of oil in the lubrication channel between the main bearing and the connecting rod bearing in the crankshaft of an internal combustion engine. The requirement for high service life and proper operation of these bearings, while minimizing input power of the lubrication system, lead to the need to understand the function of these structural parts in detail. To simulate and visualize this process, an experimental device was created. The device allows the experimenters to change individual parameters such as rotation speed, oil pressure, oil temperature, and aeration, while simultaneously visualizing the process with the help of a special rotating camera. These parameters are then obtained by image processing. In this way, the following influences are investigated here: at oil temperatures of 30, 50, and 80°C, relative oil pressures of 1, 2, 3, and 4 bar, at undissolved air in the oil of 5 and 10 vol% and crankshaft station speeds from 0 to 6000 1/min. The work is inspired by previously known publications by other authors. Their results were obtained mainly using computational methods. In the case of experiments, the authors used indirect methods of measurement using pressures and flows. Therefore, this work has a great contribution in the experimental area. The results of the experiments show the influence of the tested parameters on the gradual limitation of the oil flow through the channel. At a relative oil pressure of 1 bar and a crankshaft speed of 6000 1/min, the pressure even drops to 0 bar, and the oil flow through the channel collapses. The results of image processing show not only the area of the channel filled with oil, but also the distance of the beginning and end of the air bubble from the beginning of the channel.
Structural topology optimization for vehicle structures under static loading is a well-established practice. Unfortunately, extending these methods to components subjected to dynamic loading is challenged by the absence of sensitivity coefficients: analytical expressions are unavailable and numerical approximations are computationally impractical. To alleviate this problem, researchers have proposed methods such as hybrid cellular automata (HCA) and equivalent static load (ESL). This work introduces a new approach based on equivalent static displacement (ESD). The proposed ESD method uses a set of prescribed nodal displacements, simulating the resultant reaction forces of a body subjected to dynamic loading, at different simulation time steps to establish the boundary conditions for each corresponding model—one model for each simulation time. A scalarized multi-objective function is defined considering all the models. A gradient-based optimizer is incorporated to find the optimal topology. Then, a new dynamic analysis is performed, the new ESD is defined for each model, and a new topology is obtained. The iterative process continues until convergence. Furthermore, this work also demonstrates the extension of the proposed ESD method in the topology optimization of multibody systems. To this end, the result shows an internal combustion engine's iterative topology optimization of the connecting rod and piston. Additionally, results from multiple load case problems have been presented to prove the effectiveness of the ESD methodology.
During a recent Bosch tech showcase, we spoke with Joe Dear, engineering manager for electric propulsion systems at Linamar. The Guelph, Ontario-based parts manufacturer is no stranger to building unsung components for the auto industry, including gears, camshafts, connecting rods, and cylinder heads. The Linamar team was demonstrating a modified Ram 2500, a collaboration between Bosch and Linamar, that was outfitted with a prototype electric powertrain and new e-axles: a rigid axle on the rear (with a Bosch motor and inverter) and a steering axle up front.
This SAE Standard was developed to provide a method for indicating the direction of engine rotation and numbering of engine cylinders. The document is intended for use in designing new engines to eliminate the differences which presently exist in industry.
With recent advancements to create light weight engines and therefore, to design stronger and lighter connecting rods, automobile manufacturers have looked upon vanadium micro-alloyed steels as the material of choice. These materials have been developed keeping in mind the strength and manufacturing requirements of a connecting rod. Since, 36MnVS4 has been the most popular of this category, the same has been discussed in this paper. The transition of manufacturers from the traditional C70S6 grade to the new 36MnVS4 must be dealt with in-depth study and modification of processes to adapt to new properties of the latter. C70S6 is a high carbon grade with superior fracture split whereas 36MnVS4 is a medium carbon grade with superior strength and ductility owing to the presence of vanadium. This paper deals with the study of challenges in mass production of connecting rod using 36MnVS4 grade and overcoming the same using optimization of processes like controlled cooling, stress-relief annealing, notch scribing and fracture-splitting. Latest trends in scribing techniques and their effects on fracture behavior have also been studied in detail with the help of scanning electron microscopy.
The engine power cylinder is comprised of the piston, piston rings, and cylinder. It accounts for a significant amount of total engine friction within reciprocating, internal combustion engines. Reducing power cylinder friction is key to the development of efficient internal combustion engines. However, isolating individual power cylinder tribocouples for detailed analysis can be challenging. In this work, a new reciprocating liner test rig is developed and introduced. The rig design is novel, using a stationary piston and a reciprocating cylinder liner. Friction is calculated from the force measured in the connecting rod which supports the piston. The rig allows for independent control of peak cylinder pressure, speed, and lubricant temperature. Using the newly developed test rig, several technologies for friction reduction are evaluated and compared. Friction reducing technologies include the use of a low-friction TiSiCN nanocomposite coating applied to the piston rings, a lubricant viscosity study with engine oils ranging between SAE 0W-16 to SAE 10W-40 viscosity grades, and the impact of a special organic friction modifying oil additive. Results indicate that significant reductions in friction may be obtained using specialty coatings and optimized lubricating oils. Finally, results from the new reciprocating liner test rig are compared to data generated in chassis dynamometer vehicle fuel economy testing, showing excellent agreement.
This document describes methodologies to determine the causes blow-by oil consumption caused by the power cylinder.
This document describes methodologies to determine the causes of high oil consumption caused primarily by the power cylinder system.
Because of ever increasing demand for more fuel efficient engines with lower manufacturing cost, compact design and lower maintenance cost, OEM’s prefer three cylinder internal combustion engine over four cylinder engine for same capacity, though customer demands NVH characteristics of a three cylinder engines to be in line with four cylinder engine. Crank-train balancing plays most vital role in NVH aspects of three cylinder engines. A three cylinder engine crankshaft with phase angle of 120 degrees poses a challenge in balancing the crank train. In three-cylinder engines, total sum of unbalanced inertia forces occurring in each cylinder will be counterbalanced among each other. However, parts of inertia forces generated at No.1 and No. 3 cylinders will cause primary and secondary resultant moments about No. 2 cylinder. Conventional method of designing a dynamically balanced crank train is time consuming and leads to rework during manufacturing. Also, different vehicle models with a same engine can call for different crank-train options resulting in increased development time and efforts. This paper discusses a numerical and digital approach for designing crank train of a three cylinder gasoline engine with dynamically balanced for any option required by vehicle. This approach eliminates the iterative process of prototyping. Multibody dynamic model of 1200 cc three cylinder gasoline engine crank train is developed with inertia properties of all child parts including crankshaft, piston and connecting rod. Reciprocating and rotating inertia forces with their moments were considered for respective child parts. Reasonable tolerances to achieve desired static and dynamic balance in production parts were determined by this approach. A sensitivity study to understand influence of counterweights on crankshaft balancing is also performed using this approach. All values and correlations developed in this approach are validated on physical engines.
In this work, a dynamically loaded hydrodynamic journal bearing test rig is developed and introduced. The rig is a novel design, using a hydraulic actuator with fast acting spool valves to apply load to a connecting rod. This force is transmitted through the connecting rod to the large end bearing which is mounted on a spinning shaft. The hydraulic actuator allows for fully variable control and can be used to apply either static load in compression or tension, or dynamic loading to simulate engine operation. A variable speed electric motor controls shaft speed and is synchronized to the hydraulic actuator to accurately simulate loading to represent all four engine strokes. A high precision torque meter enables direct measurements of friction torque, while shaft position is measured via a high precision encoder. Data generated on the test rig is also presented, and includes frictional torque loss, cumulative energy consumption during transient operation, and starting energy during stop/start testing.
Increasing combustion pressure, low viscosity oils, less oil supply and the increasing stress due to downsizing of internal combustion engines (ICE) lead to higher loads within the bearing. As the mechanical and tribological loads on the piston pin bearings have a direct impact on the service life and function of the overall engine system, it is necessary to develop a robust tribological design approach. Regarding the piston pin bearing of a diesel engine, this study aims to describe the effects of different parameters on a DLC-coated piston pin within the bearing. Therefore, an external engine part test rig, which applies various forces to the connecting rod and measures the torque on a driven pin, is used to carry out validation measurements. The special feature of the test bench is the way the piston is beared. For the first experiments, the piston crown is placed against a plate (plate-bearing); later, this plate-bearing is replaced by a hydrostatic bearing. The new bearing is designed to allow deformation under reoccurring pressure by pressing the piston into an oil bath. This should approximate the combustion chamber pressure. For the first validation of the measurement results so-called run-out tests are used, which represent the torque over a speed range. Therefore, the plate-bearing is used as well as static and dynamic load. Different lubrication variants are compared for both bearings, whereby the increased elastic deformation impacts on the lubrication. A good reproducibility is shown by repeating the same measurements several times. The running-in behaviour of the bearing is also discussed. Afterwards the parameters, which have the highest influence on the friction, will be pointed out. The test bench is used to validate a multi-body simulation with a lubricating film coupling. Due to the complexity of the calculation, a very precise validation is necessary in order to be able to make reliable statements about the physical events in the piston pin bearing. Different gap widths, fine geometries, oil temperatures, lubricant properties, surface properties and the deformation of the bodies in the model are taken into account. Finally, the first calculations are analysed, a validation method for the piston pin bearing calculation including DLC coated piston pins is developed and used for an MBS calculation with a lubricating film coupling.
In order to meet upcoming emission targets, an increasing number of ships using Liquefied Natural Gas (LNG) as fuel have been put into service. In this context, many shipowners are particularly interested in the dual-fuel (DF) large-engine technology, which enables ships to operate with both gaseous and conventional liquid fuels. The use of different combustion principles in DF engines requires a layout of the base engine with a relatively low compression ratio (CR) for the gas mode to prevent unstable combustion (knocking). However, this layout leads to disadvantages in the Diesel operation mode, which requires a higher CR for optimal fuel efficiency. Therefore, a two-stage variable compression ratio (VCR) system is a technology particularly suitable for DF engines. It allows to reduce fuel costs by approximately 5.5%. This article presents an innovative VCR connecting rod (conrod) design for modern DF engines that adapts the piston position by changing the effective conrod length. The VCR system is developed by the Institute for Combustion Engines of the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University together with Forschungsgesellschaft für Energietechnik und Verbrennungsmotoren (FEV) Europe GmbH. It is equipped with a novel functional principle inside the conrod’s small eye specifically tailored to large engine boundary conditions. The system includes an advanced hydraulic circuit combining the function of a hydraulic freewheel, the oil supply for piston cooling, and a mechanical locking device (LD) for both CRs. In a comprehensive simulation study, the layout and the system behavior of the new hydraulic circuit are presented using a one-dimensional (1D) hydraulic-mechanical simulation model, which was validated in advance with measurement data from a passenger car (PC) engine. The study intends to examine the functional behavior of the VCR system during engine operation. The focus is on the switching process between the two CRs, as well as on the fixed CR operation. The aim is to provide a deeper understanding of the hydraulic-mechanical behavior and to identify special requirements on the system.
A spark-ignition engine commonly induces tumble flow because it generates high turbulence, which is a crucial factor in determining the flame propagation speed. Since tumble affects not only the flame propagation speed but also the various in-cylinder phenomena, it predominantly determines the performance of the engine. In that sense, many studies have been conducted to investigate tumble. Although various studies have revealed the characteristics of tumble numerically and experimentally, there has been no research to identify the physical mechanisms of these characteristics. Although some studies specified the mechanisms from an angular momentum perspective, the theory was insufficient to explain the entire phenomena of tumble. Hence, this study attempts to comprehend the fundamental causes of tumble phenomena such as ‘spinning up’ and ‘vortex breakdown’ from the perspective of kinetic energy. The movement characteristics of the tumble center during the compression stroke are also identified. Although this study addresses the formation of tumble, it primarily focuses on the compression stroke, when the influence of the piston on tumble is significant. To simplify this analysis work, the in-cylinder velocity vector is assumed to be divided into two velocity components: tumble velocity and piston-induced velocity. With this assumption, the abovementioned features of tumble are elucidated with a physics-based analysis. The tumble behaviors depend greatly on the timing of intake valve closing. To check the validity of the predicted behaviors, the various intake valve operation strategies and connecting rod length results obtained from 3D computational fluid dynamics were considered. Consequently, this study provides insight into tumble, which can be used to more accurately predict the flow variances according to different engine conditions.
With the modernization of the technology, significant emphasis has been given to weight reduction in the number of engine components. This change is predominantly governed by the introduction of composites and ceramics. The crankshaft is an important part of an IC engine that converts the reciprocating motion of the piston into rotary motion through the connecting rod. This paper is focused on the weight optimization of the crankshaft by analyzing it for different stresses and dynamics loads using different materials viz. AISI 4340, Al B4C, AISI 4330M, 42-CrMo-4, AISI 6061-T6, and Aluminum alloy. Computational study of the different candidate materials for the crankshaft is done using an inline 4-cylinder diesel engine. A standard 3D model of the crankshaft is made using DS Solid works 2013 software and the computational analysis is being carried out using Ansys Workbench. The study focuses on decreasing the weight of the crankshaft while maintaining not much alteration to induced stresses and deformation, therefore increasing the efficiency and torque output of the engine. Analysis of each candidate material is done for maximum pressure and maximum torque conditions simultaneously and the results are compared and evaluated to find the suitable material with less density and good strength to weight ratio.
The general objectives of this research are the identification of relevant factors that influence the movement and rotation behavior of the piston pin and to characterize the oil filling ratio in the piston boss. For this purpose, an experimental measurement campaign with load and speed variation is carried out on an engine test bench. The key challenge is the implementation of the extensive measurement technology on a series V6 engine. For the detection of the radial piston pin movement in stroke and transversal direction four eddy current sensors are used, two per direction. With a combined measuring principle the oil filling ratio can be determinated. Therefore two additional capacitive sensors are placed between the eddy current sensors. Depending on the hydrodynamic friction conditions in the piston pin bearing as well as the thermal and mechanical boundary conditions, the pivoting movement of the connecting rod initiates the rotation of the piston pin. To record this rotational movement an additional eddy current sensor is applied. Therefore the measuring surface in the inner bore of the piston pin has an electric discharge machined (EDM) spiral contour. As a result of the large number of measurement wires two linkage systems are applied in one cylinder. The smaller linkage system is connected with the piston, the larger one is applied to the connecting rod. Due to remarkable solutions a successful design and application of the different measuring techniques could be realized. An improved understanding of the piston pin movement behavior can be achieved by evaluating the measurement results and analyzing various influencing factors.
The forged connecting rod and pin experience a large amount of stresses due to cyclic load for a long period of time induced by the reciprocating movement of the piston. The proposed work focused to produce lightweight composites with high strength using waste flyash and simple manufacturing process. In this context, the proposed experimental work was formulated to develop aluminium alloy hybrid metal matrix composite of A356 alloy with silicon carbide and flyash processed through stir cum squeeze casting process under optimal parametric condition. The samples were subjected to varying flyash content of 0, 5, 10wt.% and SiC of 5wt.% kept constant. Responses like metallography, hardness, impact strength, flexural strength, fatigue strength were observed for the manufactured hybrid composites. There was a significant improvement in the properties with a higher weight percentage addition of 10wt.% flyash and 5wt.% SiC with A356 hybrid composites. As the waste flyash and hard ceramic particles act as a barrier for dislocation movement and resist plastic deformation followed by cyclic strength was improved. The micro pour free densification during squeezing also added for the above property. The coupled effect of both the reinforcement’s addition and squeezing of the liquid metal shows enormous results than the other combinations and similar researcher's findings. So, the developed hybrid composites and their processing route are recommended for the automotive industries to fabricate connecting rod in the future.
Reducing the mechanical friction of internal combustion engines could play a major role in improving the brake specific fuel consumption (BSFC). Hence, it is important to reduce the friction at every component and sub-system level. In the present work, the oil pump friction of a 1.5 liter 4-cylinder diesel engine is optimized by reducing the oil pump displacement volume by 20%. This could be achieved by adopting an optimized oil supply concept which could reduce the oil leakage through the main bearings and connecting rod bearings. A 1-dimensional oil flow simulation was carried out to predict the oil flow distribution across the engine for different speeds. The results indicate that the oil leakage through the main bearings and connecting rod bearings contribute to ~25% of the total oil flow requirement of the engine. In a conventional oil supply concept, the big-end bearing of each connecting rod is connected to the adjacent main bearing through an internal oil hole. Though this is a standard and robust oil supply concept, the oil leakage through the bearings is relatively higher that demands a bigger oil pump. Hence, several design options were investigated to reduce the overall oil leakage through the bearings using a 3-dimensional elasto-hydrodynamic (3D EHD) simulation tool. Moreover, the robustness of the bearings was also checked by comparing the minimum oil film thickness, total contact pressure, asperity contact pressure and adiabatic temperature rise. Based on the results, the oil feed concept was optimized in such a way that the oil supply for two of the big-end bearings is supplied from one main bearing. The main bearing shells were optimized in line with the new oil supply concept to overcome the challenges of operating under the peak cylinder pressure of 180 bar. Overall, with this optimized oil supply concept, the oil pump size could be reduced from a theoretical displacement volume of 24 cc/revolution to 19.5 cc/revolution. Thus, the optimization of the oil supply concept of the engine bearings could help to reduce the oil pump size and corresponding power consumption.
In this work, Calculations and design of connecting rod of IC engine is performed in innovative way. Calculation point of view, Con rod is the utmost critical component of IC Engine as it is the part which translates reciprocating forces into rotary forces and thus creates unbalance in engine. From the functionality point of view, connecting rod must have the higher inertia at the lowest weight. Different forces acting on con rod are: - Peak combustion pressure, inertia force of reciprocating masses, Weight of Reciprocating parts and frictional forces due to cylinder wall thrust. It experiences complex forces of compression and tensile in cyclic manner, which repeats after each 720 (in case of 4 stroke) or 360 (in case of 2 stroke) phase of degree. Hence, the design calculations are analyzed for the axial compressive as well as axial tensile loads considering the fatigue strength of con rod. This literature computes the required size and strength in the critical areas of failure. The calculation methodology is also cross confirmed by applying it on existing three state of the art con rods of different categories of engine, like 2 wheeler petrol engine, 4 Cyl diesel engine and Heavy Vehicle Engine.
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