Tetrahedral Amorphous Carbon Coatings for Friction Reduction of the Valve Train in Internal Combustion Engines

AbstractThe friction between two sliding surfaces is probably one of the oldest problems in mechanics. Frictional losses in any I.C. engine vary between 17% and 19% of the total indicated horse power. The performance of internal combustion engines in terms of frictional power loss, fuel consumption, oil consumption, and harmful exhaust emissions is closely related to the friction force and wear between moving parts of the engine such as piston assembly, valve train, and bearings. To solve this problem, most modern research in the area of Nanotribology (Nanolubricants) aims to improve surface properties, reduce frictional power losses, increase engine efficiency, and reduce consumed fuel and cost of maintenance. Nanolubricants contain different nanoparticles such as Cu, CuO, TiO

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Nonlinear Transient Response of a High Speed Driven Valve System and Stresses in Valve Springs for Internal Combustion Engines

Journal of Vibration and Acoustics ◽

10.1115/1.3269851 ◽

1989 ◽

Vol 111 (3) ◽

pp. 264-271 ◽

Cited By ~ 2

Author(s):

K. Nagaya

Keyword(s):

High Speed ◽

Internal Combustion Engines ◽

Three Dimensional ◽

Beam Theory ◽

Internal Combustion ◽

Valve Train ◽

Combination Method ◽

Combustion Engines ◽

Valve System ◽

Cam Profile

This paper presents a method for solving the dynamic response problems of a driven valve system and the stress problem of valve springs for internal combustion engines. In this system there is hysteresis behavior in the spring constants during the rotation of the cam shaft. To treat this nonlinearity, the rigidity of each section is assumed to be one of a partly linear spring. For the valve trains, the cam profile is complex in general. To treat a general cam profile, this paper applies a combination method of the Fourier expansion, the Laplace transform and the analytical connection methods, and gives a response of valve trains. This paper also presents a theoretical result for the stresses in the valve spring due to the motion of the valve train based on the three dimensional curved beam theory.

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Enhancing the Geometrical Performance Using Initially Conical Cylinder Liner in Internal Combustion Engines—A Numerical Study

Applied Sciences ◽

10.3390/app10113705 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3705

Author(s):

Ahmad Alshwawra ◽

Florian Pohlmann-Tasche ◽

Frederik Stelljes ◽

Friedrich Dinkelacker

Keyword(s):

Internal Combustion Engines ◽

Thermal Stresses ◽

Numerical Study ◽

Cylinder Liner ◽

Internal Combustion ◽

Friction Reduction ◽

Cylindrical Shape ◽

Combustion Engines ◽

Cold State ◽

The Impact

Reducing friction is an important aspect to increase the efficiency of internal combustion engines (ICE). The majority of frictional losses in engines are related to both the piston skirt and piston ring–cylinder liner (PRCL) arrangement. We studied the enhancement of the conformation of the PRCL arrangement based on the assumption that a suitable conical liner in its cold state may deform into a liner with nearly straight parallel walls in the fired state due to the impact of mechanical and thermal stresses. Combining the initially conical shape with a noncircular cross section will bring the liner even closer to the perfect cylindrical shape in the fired state. Hence, a significant friction reduction can be expected. For the investigation, the numerical method was first developed to simulate the liner deformation with advanced finite element methods. This was validated with given experimental data of the deformation for a gasoline engine in its fired state. In the next step, initially conically and/or elliptically shaped liners were investigated for their deformation between the cold and fired state. It was found that, for liners being both conical and elliptical in their cold state, a significant increase of straightness, parallelism, and roundness was reached in the fired state. The combined elliptical-conical liner led to a reduced straightness error by more than 50% compared to the cylindrical liner. The parallelism error was reduced by 60% to 70% and the roundness error was reduced between 70% and 80% at different liner positions. These numerical results show interesting potential for the friction reduction in the piston-liner arrangement within internal combustion engines.

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