Rod Bearings Research Articles

Proračunski modeli vijčanih spojeva motora s unutarnjim izgaranjem

Simplified calculation methods of internal combustion engine screw joints are presented, with respect to screw fastenings of connecting rod bearing; crankshaft main bearing and fuel pump camshaft bearing. Design criteria for proper bolt dimensioning and tightening force estimate as conditions for screw joint safety are discussed.

Modelling of a Radial-Piston Hydraulic Motor

The paper is concerned with the theoretical modelling of the torque-producing mechanism in a radial-piston, eccentric-type, hydraulic motor for low-speed operation. The major difficulty in such an analysis is the description of the frictional losses which, at low speeds, principally result from boundary lubrication conditions. The level of friction is also dependent on the distribution of the transferred forces and the amount of distortion in the bearings These forces vary during the pressure cycle, and squeeze-film effects are introduced between the bearing faces during the period of time following the introduction of pressure into the cylinder. The interaction between the frictional effect in the connecting rod bearing and the operation of the hydrostatic slipper is central to the modelling process. Friction coefficients in the bearings are determined that predict similar efficiencies to those obtained from test measurements on a low-speed motor. The evaluation of internal motor parameters is then carried out using these coefficient values in the model. Such a model is invaluable for establishing critical areas in the mechanism and for predicting the effect of component design changes on the motor performance.

A Study an Optimum Structure of Hydrodynamic Bearings in High-Output S.I. Engines. 2nd Report, A Measurement of Oil Film Pressure Distribution in Connecting Rod Bearing with Test Rig.

In designing an optimum connecting rod, it is necessary to determine the oil film pressure (OFP) distribution at the big end under actual engine operating conditions because these conditions must be used as the boundary conditions of a structural analysis. Since it is very difficult to measure the OFP distribution, a bearing test rig has been developed to simulate the actual load of an operating engine. Measured data obtained with this test rig show a lower maximum oil film pressure and a wider pressure angle than the calculated results.

A Measurement of Oil Film Pressure Distribution in Connecting Rod Bearing With Test Rig

In designing an optimum connecting rod, it is necessary to determine the oil film pressure (OFP) distribution at the big end under the actual engine operating conditions because it is used as the boundary conditions in a structural analysis. Since it is very difficult to measure the OFP distribution, a bearing test rig has been developed to simulate the load of an operating engine. The measured data on the cap side of the connecting rod obtained with this test rig shows a lower maximum oil film pressure and a wider pressure angle than those on the rod side.

Statistical Analysis of Failure Time Distributions for Great Lakes Marine Diesels Using Censored Data

Field-censored failure data collected from six identical Colt-Pielstick PC2-400 Great Lakes marine diesel engine components are analyzed. Appropriate censored lifetime data analysis techniques are presented and applied to obtain the probability density function (PDF) parameter estimates for the entire population when only a portion of that population has failed. Weibull and exponential PDF parameters are evaluated for seven components—namely, cylinder pistons, heads, jackets, liners and O-rings, connecting rod bearings, fuel cams, and turbochargers. Reliability and hazard functions for these items are presented and discussed. It is shown that the exponential model is inappropriate for these items.

A study on the optimum structure of hydrodynamic bearing in high-output S.I. engines. 1st Report, Factor analysis on M.O.F.T. at the connecting rod bearing in S.I. engines.

This analysis aims to determine the severest engine operating condition for deterioration of oil film lubrication around the crankpin journal, and to clarify the reason why minimum oil film thickness (M. O. F. T.) occurs during engine operation. As a result, that operating condition is experimentally found to raise the surface temperature of the crankpin at 7400 rpm and no/load or deceleration. According to the narrow bearing theory for dynamic loading, a decrease in M. O. F. T. is caused by the following factors: the first is a deformation of the connecting rod and crankshaft, the second is an increase in oil temperature and the third is an increase in the weight of reciprocating moving parts.

Analysis of Crankshaft Bearings Using a Mass Conserving Algorithm

A mass conserving algorithm (Elrod algorithm) which uses the Jakobsson, Floberg, and Olsson cavitation boundary conditions has been implemented to analyze crankshaft bearings. The main and connecting rod bearings of a typical automotive engine are considered. Some sample steady-state results are presented. The inverse problem (given the load, find the journal orbit) is solved for real engine loads. Comparisons are made with a non-conservative algorithm based on the Reynolds boundary condition. Significant differences in the cavitation zones and oil flows are observed between the two algorithms. In all cases, the oil flow into the bearing is found to match the oil flow out of the bearing for the Elrod algorithm. Presented at the 44th Annual Meeting in Atlanta, Georgia May 1–4, 1989

An Optimum Connecting Rod Design Study—A Lubrication Viewpoint

The effect of support structure on the performance of a connecting rod bearing is analyzed by elastohydrodynamic lubrication theory. The support structure is modified iteratively until an optimum design is obtained. With the connecting rod of a typical gasoline engine as an example, it was found that a 150 percent improvement in film thickness and a 34 percent reduction in peak pressure can be obtained by changing the structural design. This design, however, increases the peak octahedral shear stress in the rod. Structural design changes considered were found to have surprisingly little effect on the power loss of the bearing.

An Optimum Short Bearing Theory for the Elastohydrodynamic Solution of Journal Bearings

An approximate method for solving the elastohydrodynamic (EHD) lubrication problem has been developed. The method is based on two assumptions: the separation of variable for pressure and a parabolic pressure distribution in the axial direction. To solve the governing equations, the Newton-Raphson method, in conjunction with Murty’s algorithm, is used. The finite-element and the finite-difference methods are then used to obtain approximate solutions. The rod bearing of a typical connecting rod is analyzed by the new method. The results are compared to the full EHD solution and the rigid bearing solution. Significant reduction in computation time is realized when compared to the full EHD solution.

Starvation in Dynamically Loaded Flexible Short Journal Bearings

A starvation model is incorporated in a previously presented numerical method for calculating film thicknesses inflexible short journal bearings under dynamic load. The system of elastohydrodynamic integro-differential equations is now coupled with continuity equations for the lubricant, considering central circumferential oil grooves and a constant supply pressure. An important application of this method is the connecting rod bearing in medium speed combustion engines. Results for several groove geometries are compared with those for a fully flooded bearing.

Numerical Simulation of Dynamically Loaded Flexible Short Journal Bearings

A numerical method is proposed for calculating film thicknesses in flexible short journal bearings under dynamic load. The system of elastohydrodynamic integro-differential equations is discretized directly and solved by a 2-step Newton-Raphson method. The cavitation boundaries are located by a special discretization of the pressure. This type of condition puts practically no restrictions on the boundary alterations. The results for the con rod bearings of medium- and high-speed combustion engines are compared.

Temperature Measurements of the Connecting Rod, Piston Pin and Crankpin Bearing of an Automobile Gasoline Engine

The thermocouple wires were led from the connecting rod to the piston through in a coil which received a twisting stress only in the piston pin. From here the wires were led out by means of thecombustion chamber pass through and on the circular springmethod that had been used by the authors. From the measuring results, the followings were found. (i) The heat flow from the piston reaches to the middle part of the connecting rod, at the big end, however, this effect fade away. The temperatures of the crankpin and main bearing metal rise a certain extent above the surroundings by the friction. (ii) These temperatures are increased proportionately with the engine speed. (iii) An increasing the oil temperature increases the temperatures of the bearing-metals as same extent as it.