Probabilistic Tolerance Allocation for the Dynamics of an Internal Combustion Engine With a Flexible Connecting Rod

Author(s):  
F. Zhang ◽  
B. J. Gilmore ◽  
A. Sinha

Abstract Tolerance allocation standards do not exist for mechanical systems with flexibility and whose response are time varying, subjected to discontinuous forcing functions. Previous approaches based on optimization and numerical integration of the dynamic equations of motion encounter difficulty with determining sensitivities around the force discontinuity. The Alternating Frequency/Time approach is applied here to capture the effect of the discontinuity. The effective link length model is used to model the system and to account for the uncertainties in the link length, radial clearance and pin location. Since the effective link length model is applied, the equations of motion for the nominal system can be applied for the entire analysis. Optimization procedure is applied to the problem where the objective is to minimize the manufacturing costs and satisfy the constraints imposed on mechanical errors and design variables. Examples of tolerance allocation are presented for a single cylinder internal combustion engine with a flexible connecting rod.

Author(s):  
F. Zhang ◽  
B. J. Gilmore ◽  
A. Sinha

Abstract Tolerance allocation standards do not exist for mechanical systems whose response are time varying and are subjected to discontinuous forcing functions. Previous approaches based on optimization and numerical integration of the dynamic equations of motion encounter difficulty with determining sensitivities around the force discontinuity. The Alternating Frequency/Time approach is applied here to capture the effect of the discontinuity. The effective link length model is used to model the system and to account for the uncertainties in the link length, radial clearance and pin location. Since the effective link length model is applied, the equations of motion for the nominal system can be applied for the entire analysis. Optimization procedure is applied to the problem where the objective is to minimize the manufacturing costs and satisfy the constraints imposed on mechanical errors and design variables. Examples of tolerance allocation are presented for a single cylinder internal combustion engine.


2018 ◽  
Author(s):  
◽  
Muslim Muhsin Ali

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The main object of this dissertation is to study the dynamic analysis of an inline internal combustion engine. This dissertation presents the kinematics and kinetic analyses of an inline internal combustion engine crank mechanism, the dynamic torque imbalance and foundation forces for a single-piston and multi-piston engines are studied as well. The objectives of this dissertation are to explore the inertial-torque characteristics and foundation forces of an inline, internal combustion engine with connecting-rod joints that are evenly spaced about the centerline of the crankshaft, and to evaluate the goodness of a mass approximation that is customarily used in machine design textbooks. In this dissertation the number of pistons within the internal combustion engine is varied from 1 to 8. In order to generalize the results, the reaction force between the ground and the crank in the x-direction and y-direction equations are nondimensionalized and shown to depend upon only six nondimensional groups, all related to the mass and geometry properties of the connecting rod and crank while the reaction force between the connecting rod and the piston in the x-direction y-direction, reaction force between the crank and the connecting rod in the x-direction y-direction, reaction force between the piston and the cylinder wall, and the inertial-torque equations are nondimensionalized all related to the mass and geometry properties of the connecting rod. As shown in this dissertation, the largest torque imbalance is exhibited by a 2-piston engine. The next largest torque imbalance is exhibited by a 3-piston engine, followed by a single-piston engine (this is not monotonic). The largest foundation forces are exhibited by a single-piston engine. The next largest foundation forces are exhibited by a 2-piston engine, followed by a 3e-piston engine, and that a dramatic reduction in the foundation forces and torque imbalance may be obtained by using 4 or more pistons in the design, when using as many as 8 pistons the foundation forces and torque imbalance essentially vanishes. It should be observed that the mass approximation captures 100 percent of the variability of the actual torque imbalance for engines that are designed with an odd number of pistons equal to or greater than three. The mass approximation captures 100 percent of the variability of the actual reaction force between the piston and cylinder wall for engines that are designed with single-piston and multi-pistons. The mass approximation captures 100 percent of the variability of the actual reaction force against piston pin for engines that are designed with single-piston. It is also shown in this dissertation that the customary mass approximations for the connecting rod may be used to simplify the analysis for all engine designs without a significant loss of modeling accuracy.


2001 ◽  
Vol 123 (3) ◽  
pp. 444-454 ◽  
Author(s):  
Byung-Jik Kim ◽  
Kyung-Woong Kim

A comprehensive method of thermo-elastohydrodynamic lubrication analysis for connecting rod bearings is proposed, which includes thermal distortion as well as elastic deformation of the bearing surface. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while the bearing temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication film is absorbed by the film itself, and the remainder flows into the bearing structure. Mass-conserving cavitation algorithm is applied, and the effect of variable viscosity is included in the Reynolds equation. Simulation results of the connecting rod bearing of an internal combustion engine are presented. It is shown that the predicted level of the thermal distortion is as large as that of the elastic deformation and the bearing clearance, and that the thermal distortion has remarkable effects on the bearing performance. Therefore, the thermo-elastohydrodynamic lubrication analysis is strongly recommended to predict the performance of connecting rod bearings in internal combustion engines.


2003 ◽  
Vol 125 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Charles D. McAllister ◽  
Timothy W. Simpson

In this paper, we introduce a multidisciplinary robust design optimization formulation to evaluate uncertainty encountered in the design process. The formulation is a combination of the bi-level Collaborative Optimization framework and the multiobjective approach of the compromise Decision Support Problem. To demonstrate the proposed framework, the design of a combustion chamber of an internal combustion engine containing two subsystem analyses is presented. The results indicate that the proposed Collaborative Optimization framework for multidisciplinary robust design optimization effectively attains solutions that are robust to variations in design variables and environmental conditions.


2015 ◽  
Vol 741 ◽  
pp. 810-813
Author(s):  
Shao Ni Wang

This paper described examples of genetic algorithm in valve spring optimization design of internal combustion engine, which solve the optimal values of the design variables by constructing multi-objective function. The technical problems that complex performance can't be considered in the calculation were solved in designing the spring, the method has many advantages such as simple universal, strong robustness, and wide application range; it is an essential and critical intelligent computing technology in the future mechanical optimization design.


Author(s):  
Charles D. McAllister ◽  
Timothy W. Simpson

Abstract In this paper, we introduce a multidisciplinary robust design optimization formulation to evaluate uncertainty encountered in the design process. The formulation is a combination of the bi-level Collaborative Optimization framework and the multiobjective approach of the compromise Decision Support Problem. To demonstrate the proposed approach, the design of a combustion chamber of an internal combustion engine containing two subsystem analyses is presented. The results indicate that the proposed Collaborative Optimization framework for multidisciplinary robust design optimization effectively attains solutions that are robust to variations in design variables and environmental conditions.


2018 ◽  
Vol 224 ◽  
pp. 02015
Author(s):  
Olga Zhed ◽  
Vladimir Kopylov ◽  
Adolf Koshelenko

The intensity of the contour strains of the oil channel is determined by the method of photomechanics in the consequence of the loads of the crankpin in the working cycle of the internal combustion engine. The studies have made it possible to establish the qualitative and quantitative composition of the stresses on the hole contour of the oil channel against deformation of the bending and torsion of its connecting rod.


Author(s):  
Bogdan T. Fijalkowski

An advanced reciprocating internal combustion engine without a crankshaft and connecting rod mechanisms that the author would like to present is based on another law of physics. The invention titled ‘Nano-Magneto-Rheological Mechatronic Commutator Internal Combustion Engine’, that is concisely termed the Fijalkowski engine by someone, is based on a whole new propulsion engineering solution that has no analogies in the world. Thus, this paper focuses on an advanced reciprocating internal combustion engine termed the Fijalkowski engine, which may utilize a nano-magneto-rheological mechatronic commutator that may replace the crankshaft and connecting rod (conrod) mechanisms. This mechatronic commutator may let nano-magneto-rheological rotary ratchets oscillate in a controlled wobble while keeping the output shaft spinning smoothly; and although opposed pistons and opposed cylinders similar to those in automotive ‘boxer’ engines may power the Fijalkowski engine, it may also utilize opposed cylinders containing four pairs of two end-to-end opposed pistons for higher power densities. The nano-magneto-rheological mechatronic commutator may be utilized to convert between one form of mechanical motion that is linear, reciprocating motion of pistons and another — that is rotary motion of the output shaft.


2017 ◽  
Vol 8 (6) ◽  
pp. 632-647 ◽  
Author(s):  
Andrea Gilioli ◽  
Dario Braconi ◽  
Mario Guagliano

Purpose The purpose of this paper is to apply a computer-aided engineering approach in order to improve the performance and the reliability of an innovative internal combustion engine. The engine is called twin engine packs system and it consists into the presence of two independent piston engines working in the same crankcase, thus allowing the helicopter to meet the safety standards of the fail-safe design approach, as happens with the twin-turbine helicopters, but with reduced operative costs. The goal is to propose to the designers modifications aimed to improve the performance of the components. Design/methodology/approach The crankshaft, connecting rod and the piston of the engine have been investigated by means of numerical FE models. Numerical fatigue assessments have been performed along with vibrational modes and buckling analysis in order to verify the structural integrity of the system. Findings On the basis of the numerical results, some modifications have been proposed to the designers and the originally proposed geometry has been modified. Eventually, the mass of the engine has been reduced keeping a high reliability level. Practical implications The prototype of the engine has been built following the modifications proposed in this paper. This paper represents a comprehensive application of a CAE methodology to a real industrial application. Originality/value This paper shows a complete CAE procedure applied to a real working engine whose performances and reliability have been improved by following the findings of this paper.


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