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This paper deals with the friction performance results for various new concept piston skirt profiles. The program was conducted under the assumption that friction performance varies by the total amount of oil available at each crank angle in each stroke and the instantaneous distribution of the oil film over the piston skirt area. In previous papers [1,2] it was that lower friction designs would be expected to show higher skirt slap noise. This paper discusses the correlation between friction and skirt slap for each new concept profile design. Finally, this paper explains the friction reduction mechanism for the test samples for each stroke of the engine cycle by observing the skirt movement and oil lubrication pattern using a visualization engine.

An analytical method is presented in this paper for simulating piston secondary dynamics and piston-bore contact for an asymmetric half piston model including elastohydrodynamic (EHD) lubrication at the bore-skirt interface. A piston EHD analysis is used based on a finite-difference formulation. The oil film is discretized using a two-dimensional mesh. For improved computational efficiency without loss of accuracy, the Reynolds’ equation is solved using a perturbation approach which utilizes an “influence zone” concept, and a successive over-relaxation solver. The analysis includes several important physical attributes such as bore distortion effects due to mechanical and thermal deformation, inertia loading and piston barrelity and ovality. A Newmark-Beta time integration scheme combined with a Newton-Raphson linearization, calculates the piston secondary motion.

This paper introduces a new hypereutectic aluminum alloy for piston casting, an improved casting process and a new re-melting procedure. The resulting microstructures improve the fatigue performance of the piston combustion bowl region exposed to severe cyclic thermal and mechanical loading in modern diesel engine applications. It is shown how composition and material properties of the new alloy increase the material's fundamental properties, compared to an existing hypereutectic alloy. The new casting process minimizes the occurrence of fine oxide inclusions which helps to exploit the fundamental material strength. Finally the paper describes the combustion bowl re-melting process and gives engine validation results to illustrate its considerable influence on premature fatigue failure.

Due to increasing economic and environmental performance requirements of internal combustion engines, piston manufacturers now focus more on lower friction designs. One factor strongly influencing the friction behavior of pistons is the dynamic interaction between lubricating oil, cylinder bore and piston. Therefore, the dynamic effect of the oil film in the gap between the liner and piston has been studied, using a single cylinder engine equipped with a sapphire window. This single cylinder engine was also equipped with a floating liner, enabling real-time friction measurement, and directly linking the oil film behavior to friction performance of pistons.

The engineering of an improved performance PTFE crankshaft (IPPC) seal is a challenge in the pursuit of longer service life and reduced total cost of ownership in the vehicular industry. This paper briefly reviews from the authors’ perspective the evolution of laydown PTFE seal design and details the IPPC seal features along with bench testing performance data.

The interest in using combustion pressure in engine control systems has initiated development activities to integrate pressure sensors into existing engine components. Since cylinder head gasket contacts the combustion chamber of multiple cylinders, the ability to add pressure-sensing capability is of unique interest. Two viable multi-layer steel cylinder head gasket design approaches have been developed to fulfill this interest. These designs offer the full sealing performance of traditional multi-layer steel designs, but also include accurate pressure sensors packaged in a total gasket thickness realistic to modern engines.

The objective was to rank piston friction and noise for three piston architectures at three cold clearance conditions. Piston secondary motion was measured using four gap sensors mounted on each piston skirt to better understand the friction and noise results. One noticeable difference in friction performance from conventional designs was as engine speed increased the friction force during the expansion stroke decreased. This was accompanied by relatively small increases in friction force during the other strokes so Friction Mean Effective Pressure (FMEP) for the whole cycle was reduced. Taguchi's Design of Experiment method was used to analyze the variances in friction and noise.

Lead is well recognized as having environmental and health risks. The elimination of lead from automotive components has been accelerated by the European End of Life Directive as well as litigation concerns in the U.S. In response to these circumstances, two new lead-free bronze materials have been developed as replacements for SAE 792 (CuSn10Pb10). The two lead free materials are sintered bronzes with nominal compositions CuSn10Bi3 and CuSn8Ni. The characteristics and performance of these materials are compared and contrasted to sintered and cast SAE 792. Fatigue strength, mechanical properties, corrosion resistance, and wear resistance are described and related to the microstructural and application conditions. The CuSn10Bi3 material is preferred for SAE 792 applications having poor lubrication or high-speed conditions, typically in spark ignition connecting rod bushings or highly loaded transmission bushings.

Ever increasing specific power of diesel engines has put huge demand on effective thermal management of the pistons for the desired reliability and durability. The piston temperature control is commonly achieved by injecting cooling oil into piston galleries, but the design of the cooling system as well as the boundary conditions used in FEA simulations have so far relied mostly on empirical methods. A numerical procedure using 3D computational fluid dynamics (CFD) has therefore been developed to simulate the cooling process and to estimate the cooling efficiency of gallery. The model is able to predict the detailed oil flow and heat transfer in gallery, of different designs and engine applications, under dynamic conditions. The resulted spatially resolved heat transfer coefficient from the CFD model, with better accuracy, enables improved prediction of piston temperature in finite element analysis (FEA).

This paper presents the development of surrogate models (metamodels) for evaluating the bearing performance in an internal combustion engine. The metamodels are employed for performing probabilistic analyses for the engine bearings. The metamodels are developed based on results from a simulation solver computed at a limited number of sample points, which sample the design space. An integrated system-level engine simulation model, consisting of a flexible crankshaft dynamics model and a flexible engine block model connected by a detailed hydrodynamic lubrication model, is employed in this paper for generating information necessary to construct the metamodels. An optimal symmetric latin hypercube algorithm is utilized for identifying the sampling points based on the number and the range of the variables that are considered to vary in the design space.

A fast and accurate journal bearing elastohydrodynamic analysis is presented based on a finite difference formulation. The governing equations for the oil film pressure, stiffness and damping are solved using a finite difference approach. The oil film domain is discretized using a rectangular two-dimensional finite difference mesh. In this new formulation, it is not necessary to generate a global fluidity matrix similar to a finite element based solution. The finite difference equations are solved using a successive over relaxation (SOR) algorithm. The concept of “Influence Zone,” for computing the dynamic characteristics is introduced. The SOR algorithm and the “Influence Zone” concept significantly improve the computational efficiency without loss of accuracy. The new algorithms are validated with numerical results from the literature and their numerical efficiency is demonstrated.

A comprehensive formulation is presented for the dynamics of a rotating flexible crankshaft coupled with the dynamics of an engine block through a finite difference elastohydrodynamic main bearing lubrication algorithm. The coupling is based on detailed equilibrium conditions at the bearings. The component mode synthesis is employed for modeling the crankshaft and block dynamic behavior. A specialized algorithm for coupling the rigid and flexible body dynamics of the crankshaft within the framework of the component mode synthesis has been developed. A finite difference lubrication algorithm is used for computing the oil film elastohydrodynamic characteristics. A computationally accurate and efficient mapping algorithm has been developed for transferring information between a high - density computational grid for the elastohydrodynamic bearing solver and a low - density structural grid utilized in computing the crankshaft and block structural dynamic response.

A new concept in thrust washers for gasoline and diesel engines has been developed. Traditionally, thrust washers have been made from the same steel-backed bimetal or trimetal materials that are used for connecting rod bearings and crankshaft main bearings. The new concept is a solid aluminum alloy, specifically formulated for optimum performance as a thrust washer material. This alloy has environmental advantages and performance characteristics superior to currently used materials. The composition, manufacturing process, and microstructure of the new concept thrust washer are briefly explained, and the performance characteristics and environmental advantages are presented.

Bore distortion was measured in a 2.0 liter in-line 4-cylinder gasoline engine, chosen because its siamesed bore design was expected to incur high bore distortion. The method adopted was to install 10 Micro-Epsilon eddy-current transducers in an invar carrier attached to the under crown of the piston. The transducers emerged through apertures in the piston at second ring level where they were in close proximity to the bore surface. A 2-beam linkage system was used to carry miniature co-axial cables to the engine exterior. Measurements were recorded at various speeds and loads up to 6000 rev/min. Maximum bore distortion was 86 microns, arising from clamping loads, thermal effects and combustion pressure. The head bolts spaced around the bore gave rise to fourth order distortion, but the dominant influence was thermal loading which induced second order distortion, attributed directly to the siamesed bore design. The combustion pressure proved to have the least influence.

Standard bonded transmission piston design specifies the use of low carbon steel for the piston carrier material. High strength low alloy (HSLA) steel is proposed for applications where load and packaging requirements dictate. The impact of carrier material selection on piston design and manufacturing needs to be comprehensively evaluated in these cases. This paper will discuss considerations for using HSLA steel and make recommendations for its application to bonded transmission pistons.