Combined multi-body dynamics and experimental investigation for determination of the cam-flat tappet contact condition

Teodorescu, Mircea; Taraza, Dinu

doi:10.1243/1464419042035935

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…Boundary friction is due to asperity interactions; the definition of friction originally expounded by Amontons. Greenwood and Tripp [25] proposed a model based on Gaussian distribution of asperities on the counterfaces, which simplifies to where τ e ≈ 2 MPa is the Eyring [26] shear stress for engine oil, A a the total area of asperity tip pairs in contact and c pb ≈ 0.17 according to Johnson [27] and Teodorescu et al [28]. When asperity interactions take place, the lubricant film is quite thin and its behaviour (in parts, i.e.…”

Section: Fictional Analysis In Piston Conjunctionmentioning

confidence: 99%

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Elasto-multi-body dynamics of internal combustion engines with tribological conjunctions

Perera

Theodossiades

Rahnejat

2010

Proceedings of the Institution of Mechanical Engineers, Part K:

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Reduction of frictional losses and NVH (Noise, Vibration, and Harshness) refinement constitute the key customer-focussed aims in internal combustion engine development. Numerical predictive tools have progressively become an important part of achieving these aims. However, the interactions and sometimes the conflicting requirements of the aforementioned objectives call for the inclusion of many phenomena in realistic models of practical significance. These phenomena occur at varying physics of scale, from micro-scale tribological conjunctions to small scale vibrations and onto large scale inertial dynamics. At the same time, the inclusion of many disciplines for a cohesive analysis will be required, such as rigid body dynamics and elastodynamics, as well as tribology. While the inclusion of such a multi-disciplinary approach is deemed essential, the use of analytical rather than numerical models, as far as possible, would render realistic predictions within the usual tight industrial timescales. This article presents an experimentally validated model of the engine piston assembly, which is based on the multiphysics, multi-scale nature of the interacting components. Furthermore, it provides predictions of some current development trends in engines such as the high output power to weight ratio and offset crankshaft. The emphasis of this article is on the integration of the kinetic reactions arising from the tribological conjunction of the dynamics of engine subsystems, piston, and crankshaft.

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Section: Fictional Analysis In Piston Conjunctionmentioning

confidence: 99%

“…where τ e ≈ 2 MPa is the Eyring [26] shear stress for engine oil, A a the total area of asperity tip pairs in contact and c pb ≈ 0.17 according to Johnson [27] and Teodorescu et al [28]. When asperity interactions take place, the lubricant film is quite thin and its behaviour (in parts, i.e.…”

Section: Fictional Analysis In Piston Conjunctionmentioning

confidence: 99%

Elasto-multi-body dynamics of internal combustion engines with tribological conjunctions

Perera

Theodossiades

Rahnejat

2010

Proceedings of the Institution of Mechanical Engineers, Part K:

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“…-M. Teodorescu and D. Taraza, 2004 [10] This paper investigates the tribological contact conditions between a polynomial automotive cam and a flat follower. The tappet spin effect is specially considered.…”

Section: Bibliographic Research Resultsmentioning

confidence: 99%

An overview of experimental methods for cam-tappet interactions

Ratamero

2023

VETOR

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In an engine, the valve train is responsible for approximately 6% to 35% of the total friction losses, with the value varying with the design and operating conditions. Even a 1% improvement in the fuel economy of a vehicle model is of great economic and environmental relevance. One of the engine systems subject to considerable friction is the control system and actuation of gas admission and discharge valves, the valve control system. Friction efforts and wear between the cam and the tappet depend on the relative speeds of the parts, the state of the surfaces in contact, the lubrication and temperature conditions, and the materials and geometries of the cam and tappet. A carefully project of the cam-tappet system is needed to preserve parts integrity and system functionality. This work presents some important experiments carried out with various cam-tappet systems, measured on engines or constructed using parts of an engine. Several important quantities are measured and analyzed by the reported experiments. The main objective of this paper is to promote a better understanding of these quantities that can be useful to engine designers to minimize energy losses or for optimize desirable mechanical characteristics of the system. Also, this paper allows researchers to plan new experiments and/or rapidly identify typical experimental results. It was possible to conclude that typical friction coefficients between cam and tappet varies from 0.05 to 0.15, that the force between valve stem-valve guide represents only about 1.5 -2% of the force acting on the valve stem, that the cam-follower friction was low for viscous oil SAE 50, compared with other lubricants, whereas camshaft bearing friction was low for lubricant SAE 5W-40 in the same engine, that the friction at the cam-follower interface decreases with increasing engine speed, that viscous oil gave greater oil film thickness as compared to the low-viscosity lubricant at the cam-follower interface, among others.

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“…It should be mentioned at this point, that the particular model is a generic friction model that was developed using simplified equations of the various principal friction components. More detailed, analytical methods are available in the literature, especially for the cases of piston rings and piston skirt, both of which suffer mixed regime of lubrication around top and bottom dead centres [25].…”

Section: Frictionmentioning

confidence: 99%

Study of crankshaft torsional deformation under steady-state and transient operation of turbocharged diesel engines

Giakoumis

Rakopoulos

Dimaratos

2008

Proceedings of the Institution of Mechanical Engineers, Part K:

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The modelling of transient operation of turbocharged diesel engines appeared in the early 1970s, and continues to be in the focal point of research due to the importance of transient response in the everyday operating conditions of engines. The majority of studies have focused so far on thermodynamics, as this directly affects heat release predictions and consequently performance and pollutants emissions. On the other hand, issues concerning the dynamics of engine operation are often disregarded or over-simplified. In the present work, an experimentally validated diesel engine simulation code is used to study and evaluate the importance of a notable engine dynamic issue, i.e. the crankshaft torsional (angular) deformations during turbocharged diesel engine operation owing to the difference between instantaneous engine and load (resistance) torques. The analysis aims ultimately in studying the phenomena under the very demanding, and often critical, transient operating conditions. Detailed crankshaft angular momentum equilibrium is formulated that takes into account instantaneous gas, inertia, friction, load as well as stiffness, and damping torque contributions. Details are provided concerning the underlying mechanism of the crankshaft torsional deformations during steady-state and transient operation. This deformation can assume significant values depending on the engine-load configuration (load change, crankshaft stiffness, kind of aspiration of the engine), and as such it is of great importance for safe engine operation.

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Combined multi-body dynamics and experimental investigation for determination of the cam-flat tappet contact condition

Cited by 8 publications

References 25 publications

Elasto-multi-body dynamics of internal combustion engines with tribological conjunctions

Elasto-multi-body dynamics of internal combustion engines with tribological conjunctions

An overview of experimental methods for cam-tappet interactions

Study of crankshaft torsional deformation under steady-state and transient operation of turbocharged diesel engines

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