Shape Optimization of Roller Follower Mechanism for Improving Mechanical Efficiency (original) (raw)
Related papers
Modern Mechanical Engineering, 2012
The current cam and follower mechanism in four stroke internal combustion engine employs a flat follower. In this work an attempt is made to change the flat face of follower to a curved face follower, so that the required point contact can be achieved. As line contact between existing cam and follower mechanism results in high frictional losses which results in low mechanical efficiency. It is observed that the frequency of vibration in the existing and modified cam and follower mechanism remains almost same. The finite element approach is used to perform the analysis.
EXPERIMENTAL ANALYSIS OF CAM ROLLER OF INTERNAL COMBUSTION ENGINE BY CHANGE IN AREA OF CONTA
Most of the IC engines used in the market have roller cam and follower mechanisms, having a line contact between the cam and the roller follower. In a effort to improve the mechanical efficiency of the mechanism the company requires us to change the line contact to a point contact. Hence it is required to change the flat roller follower to a curved profile. The existing cam & follower mechanisms used in Internal Combustion engines have a line contact between them causing frictional losses. These frictional losses in present line contact are being considered on the higher side. These frictional losses affect the total efficiency of an Internal Combustion engine. The mechanical efficiency of cam & follower mechanism is to be increase by minimising the frictional losses.The roller of rocker arm of a Hero Honda passion bike is replaced by new one to check performance experimentally.
EXPERIMENTAL ANALYSIS OF CAM ROLLER OF INTERNAL COMBUSTION ENGINE BY CHANGE IN AREA OF CONTACT
Most of the IC engines used in the market have roller cam and follower mechanisms, having a line contact between the cam and the roller follower. In a effort to improve the mechanical efficiency of the mechanism the company requires us to change the line contact to a point contact. Hence it is required to change the flat roller follower to a curved profile. The existing cam & follower mechanisms used in Internal Combustion engines have a line contact between them causing frictional losses. These frictional losses in present line contact are being considered on the higher side. These frictional losses affect the total efficiency of an Internal Combustion engine. The mechanical efficiency of cam & follower mechanism is to be increase by minimising the frictional losses.The roller of rocker arm of a Hero Honda passion bike is replaced by new one to check performance experimentally.
Lubrication and frictional analysis of cam–roller follower mechanisms
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology
In this work, a full numerical solution to the cam–roller follower-lubricated contact is provided. The general framework of this model is based on a model describing the kinematics, a finite length line contact isothermal-EHL model for the cam–roller contact and a semi-analytical lubrication model for the roller–pin bearing. These models are interlinked via an improved roller–pin friction model. For the numerical study, a cam–roller follower pair, as part of the fuel injection system in Diesel engines, was analyzed. The results, including the evolution of power losses, minimum film thickness and maximum pressures, are compared with analytical solutions corresponding to infinite line contact models. The main findings of this work are that for accurate prediction of crucial performance indicators such as minimum film thickness, maximum pressure and power losses a finite length line contact analysis is necessary due to non-typical EHL characteristics of the pressure and film thickness ...
Design Methodology Evaluating the Performance of a Follower Cam with Variable Valve Lift Mechanism
This paper aims to present a methodology for design, analysis and evaluation of follower-cam systems used for the control of valve movement in internal combustion engines. The strategy begins with the inverse engineering of the existing parts from a chosen motor, and designing them within the Dassault Catia CAD Software environment. The assembly created by the measured components is then simulated using real time conditions in SimDesigner software for Catia applications, which uses the well-known Adams Solver. In the first part of the paper, the cam profile is generated and at the second the kinematic and dynamic analysis of the variable valve mechanism is presented. The actual cam profile is metered, smoothened and transferred in 3D geometry. The whole mechanism is verified in a dynamics analysis to check the validity of the criteria for the follower-cam system design. Comparisons with standard profiles of motion were made. Also, the profile was evaluated in an experimental device, where the actual valve displacement was measured. Next follows the design of the variable valve lift mechanism. It is designed to have maximum lifts greater than the lift of the conventional mechanism, and under all other conditions of its characteristics (geometrical constraints, profile of forces, velocities and accelerations) to be better, in terms of stresses and work required, than the conventional mechanisms design. In the proposed methodology some of the conventional mechanism characteristics are maintained in order to be directly comparable with the variable valve mechanism.
Design evaluation of a follower cam with variable valve lift mechanism
International Journal of Structural Integrity, 2013
Purpose -The purpose of this paper is to present a methodology for design, analysis and evaluation of cam-follower systems used for the control of valve movement in internal combustion engines. The strategy begins with the inverse engineering of existing motor parts, designing them with the CATIA CAD Software and consequentially the created assembly is simulated using real time conditions in SimDesigner software, with the Adams Solver. Design/methodology/approach -The cam profile is generated and the kinematic and dynamic analysis of the variable valve mechanism is presented. The whole mechanism is verified in a dynamics analysis to check the validity of the criteria for the follower-cam system design. Comparisons with standard profiles of motion were made, while it is also evaluated in an experimental device, where the actual valve displacement was measured. Findings -The variable valve lift mechanism is designed to have maximum lifts greater than the lift of the conventional mechanism, with the geometrical constraints, profile of forces, velocities and accelerations to be better, in terms of stresses and work required, than the design of conventional mechanisms. Originality/value -The novelty of the paper is consisted in presenting an integrated simulation methodology in order to precisely model, in component and assembly basis, the follower cam mechanisms with variable valve lift, and using the available software to perform the kinematic and dynamic analysis. The proposed simulation methodology can be easily adapted by a design engineer to model and to analyzed kinematically and dynamically moving components and assemblies found in internal combustion engines and not only.
The globalization and economic reforms have changed the face and pace of world economy in the last two decades. The main thrust is on product quality, faster design and development and finally cheaper product.At the same time, for optimal use of these technologies, one has to converge them in a better way. To sustain in the competitive market, industries have to update their knowledge, acquire new skills to offer world-class products. Design and analysis of complex components has reached new heights with the application of Finite Element Method.Automobile Industry has benefited a lot with the development of CAD/CAM technologies, from engine performance to aesthetic appeal. The lead time to manufacture automobiles has drastically reduced in the recent times, because of advancements in Geometric modeling and Computer Integrated Manufacturing (CIM).Design of Internal Combustion (IC) Engine parts plays a crucial role in improving the functioning of an automobile. Design and modifications of all the important components are carried out to increase the performance and thereby efficiency. Many redesign concepts have been emerged for cylinder head, connecting rod,crankshaft, piston, carburetor, Fuel injection pump and other engine components. specially redesign of Crankshaft is carried out to get enough strength to sustain the gas pressure and to have the better thermal stability. Also new researches are going on to select an alternate material to cope up with the existing load cases, to get higher compression ratio, to reduce the inertia forces to increase the speed of the vehicle (by reducing the weight of the reciprocating masses).
Numerical analysis of cam and follower based on the interactive design approach
International Journal on Interactive Design and Manufacturing (IJIDeM), 2019
The contact between the cam and follower is considered as one of the most complicated problems from the lubrication point of view. The contact in this elastohydrodynamic lubrication (EHL) problem undergoes extreme variation conditions of different parameters. These include the load variation, geometry at the contact point and sliding speed. This paper presents an EHL solution for the contact problem between cam and chamfered follower (originally flat faced). The model of solution is point contact in order to accurately simulate the chamfering of the follower. The solution of Reynolds equation considers the non-Newtonian oil behavior in the calculation of the flow factors. The interactive design approach used in this paper focused mainly on the effect of chamfer as well as the other general parameters of the mechanism. The results revealed that chamfering of the follower in the axial direction has considerable effects on the performance of the mechanism. The linear modification causes significant rise in the maximum pressure and extreme thinning in the film thickness.
The problem in the design of a cam is the analyzing of the mechanisms and dynamic forces that effect on the family of parametric polynomials for describing the motion curve. In present method, two ways have been taken for optimization of the cam size, first the high dynamic loading (such that impact and elastic stress waves propagation) from marine machine tool which translate by the roller follower to the cam surface and varies with time causes large contact loads and second it must include the factors of kinematics features including the acceleration, velocity, boundary condition and the unsymmetrical curvature of the cam profile for the motion curve. In the theoretical solution the unidirectional impact stress waves with the Mushkelishvilis inverse of the singular integral equation for contact stress have been used for analytical solution and a numerical solution have bean solved using F.E.M (ANSYS 10) for stress analysis in a cam surface at condition of rise-dwell-return (R-D-R) motion of the follower, also to compare the analytical and numerical results that have been used different pressure angles in the rise and return of the motion curves in unsymmetrical cam profile for optimum design.
Optimization and a reliability analysis of a cam-roller follower mechanism
Journal of Advanced Mechanical Design, Systems, and Manufacturing, 2018
The aim of this work is to synthesize a cam mechanism with translating roller follower based on optimization approaches and reliability analysis. The study consists of two parts. At first, this study performs preliminary deterministic optimization to find the optimum size of a cam system and to ensure its high operating performance. For this, an objective function is defined and that takes into account the three major design parameters typically influence the design of this type of mechanism: the base radius of the cam, the radius of the roller and the eccentricity. Also, constraints on performance and resistance indicators such as the acceptable pressure angles, size radius of curvature of directories curves, the efficiency of the transmission and the specific contact pressure between the cam and follower are taken into account in this work. The second part is devoted to a reliability-mechanism study whose system failure probability is estimated by two complementary methods: the approximation methods FORM / SORM and Monte Carlo simulation using the Phimeca reliability engineer Software. Moreover, inverse FORM was used to provide an elasticity factors evaluation in order to carry out possibilities of the cam mechanism design and reliability improvement. The study has shown that the reliability is greatly improved.