Piston Ring Surface Research Articles

Friction Reduction Technology for Sliding Surface of Piston Ring

Friction Reduction Technology for Sliding Surface of Piston Ring

Challenges of simulating ‘fired engine’ ring-liner oil additive/surface interactions in ring-liner bench tribometer

This study focuses on evaluating the tribochemical processes occurring in a fired engine test and a bench tribometer with the aim of identifying the challenges related to simulating fired engine oil additive/surface interactions in laboratory conditions. Tribofilms formed in cylinder liner and piston ring surfaces from a fired engine test and a bench tribometer are chemically characterised using the X-ray photoelectron spectroscopy (XPS). This study confirmed that the chemical nature of tribofilms formed in a fired engine and a reciprocating bench tribometer are different, not surprising considering the substantially different lubrication environments between the tests. The factors necessary to be considered to improve the simulation of fired engine tribochemistry processes in laboratory conditions are identified and discussed.

Tribological property of TiO 2 nanolubricant on piston and cylinder surfaces

In this paper, an arc spray nanofluid synthesis system with complex ultrasonic orthogonal vibration and vortex stirring was proposed and developed for TiO 2 nanolubricant, in which TiO 2 nanoparticles were of equal roundness and consistent size. In the proposed nanofluid synthesis system, one of the electrodes and ultrasonic vibrator were assembled to form an orthogonal model with another electrode installed inside the vacuum chamber of arc discharge system, with 10 W/30 lubricant serving as the dielectric liquid. The tribological behavior of the lubricant with TiO 2 nanoparticles at average particle size 25 nm on the surface of piston ring is compared with that of the lubricant without TiO 2 nanoparticles. Experimental results showed that the coefficients of friction between the piston ring and base lubricant was 0.15; between the piston ring and TiO 2 nanolubricant was 0.14. Furthermore, the piston ring's wear rates of the base lubricant and TiO 2 nanolubricant were 0.0055 and 0.0021, respectively. After operating the piston cylinder for 8 consecutive hours in 15 and 30 days, respectively, the diameter of TiO 2 nanoparticles in the lubricant remained 25 nm in average. As observed from the piston ring surface on the 15th and 30th days through scanning electron microscope (SEM), it had less scraping than the piston lubricated without TiO 2 nanoparticles. Therefore, a lubricant added with TiO 2 nanoparticles can better protect the piston ring surface.

Evaluation of ring surfaces with several coatings for friction, wear and scuffing life

Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and emission. Many engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating period. Therefore, it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel engine. Wear and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear tester. The tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed pin. Several coatings on the ring specimen were used, such as DLC, TiN, Cr-ceramic and TiAlN, in order to improve the tribological characteristics of the ring. The coefficients of friction were monitored during the tests, and the wear volumes of the piston ring surfaces with various coatings were compared. Test results show that the DLC coating exhibits better tribological properties than the other coatings. The graphite structure of this coating is responsible for the low friction and wear of the DLC film. The TiN and DLC coatings show better scuffing resistance than the other coatings. The TiN and Cr-ceramic coated rings show good wear resistance and high friction.

Numerical analysis of piston ring pack operation

In the paper a model of a piston ring pack motion on an oil film has been analysed. The local oil film thickness can be compared to height of the combined roughness of mating surfaces of piston rings and cylinder liner. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng [6, 7] and Greenwood, Tripp [3] have been combined [12] and used in this paper. A model of a gas flow through the labyrinth seal of piston rings has been developed [13, 15]. In addition models of ring twist effects and axial ring motion in piston grooves have been applied [14, 15]. In contrast to the previous papers of the author, an experimental verification of the main parts of developed mathematical model and software has been presented. A relatively good compatibility between the experimental measurements and calculated results has been achieved. In addition this study presents the simulation results for an automobile internal combustion engine

最近のピストンリング用材料と表面改質皮膜について

最近のピストンリング用材料と表面改質皮膜について

Influence of the coatings deposited by electrophysical methods on the wear resistance of the ends of piston rings

The reliability and durability of the piston–cylinder groups (PCG) of internal-combustion engines strongly depend on the dimensions of the clearance in the “piston ring–piston groove” joint whose limiting state leads to the fracture of the ring and failure of the engine. The increase in the clearance can, in fact, be regarded as the superposition of molecular, abrasive, and corrosion wear. The maximum wear is observed at the lower ends of the ring and the groove. For pistons made of cast iron, the degrees of wear of the ring and the groove are almost identical. At the same time, for aluminum pistons, the degree of wear of the joint is almost three times higher than for cast iron and the degree of wear of the harder end surface of the ring made of cast iron constitutes 70% of the total wear [1, 2]. In view of the world trend of boosting the engines, this problem becomes especially urgent and explains the extensive search of new methods aimed at increasing the wear resistance of the end surfaces of the rings [3, 4]. Since the deposition of electroplated chromium coatings (used on the working surface of the upper compression rings) on the end surfaces would lead to a severalfold increase in the laboriousness of their production, it is reasonable to study the electrophysical methods of surface hardening. The aim of the present work is to analyze the influence of the electric-spark alloying (ESA) and cathodic ion bombardment (CIB) of the end surfaces of cast-iron piston rings on their wear resistance under the conditions of molecular and abrasive wear.

Wear resistance of laser-irradiated surfaces of piston rings

Wear resistance of laser-irradiated surfaces of piston rings

Development of Automatic Counting Machine for Piston Ring Using Light Emitting Diode (LED) Radiant Flux Control Method

An optical automatic counting machine that can count the number of piston rings used in a car engine is developed. Both edges on a piston ring are illuminate with two LEDs from the direction of±60° which is measured from the z-axis normal to the surface of the piston ring. The light scattered by the edges is detected perpendicularly upward. In this research, the technology to maintain the integrated value of the radiant fluxes of the light scattered by both edges, by controlling independently the radiant flux of the light generated by each LED, is developed. With this technology, a discontinuous point does not appear in the detected output signal, even if each LED is turned on or off. As a result, a continuous output signal can be detected when the bobbin with piston rings is driven horizontally. The number of piston rings is counted by counting the cross points between the output signal and the threshold signal, by adding the threshold signal to the detected output signal.

Metallurgical and Metrological Examinations of the Cylinder Liner-Piston Ring Surfaces After Heavy Duty Diesel Engine Testing©

This paper will discuss results of metallurgical and metrological examinations of cylinder liner and piston ring surfaces before and after 150, 1000 and 4000 hours of heavy duty diesel engine testing. Three different composition coatings and three methods of application were investigated, including electroplating, plasma and HVOF spraying. To examine metallurgical parameters such as porosity, microhardness, microstructure and their changes after testing, scanning electron microscopy and energy dispersive X-ray spectroscopy were used. The cylinder liner and piston ring surface profile and roughness parameters include Ra, Rz, Rk, Rvk, Rvk, skewness, oil retention volume, etc. The mechanisms of scuffing origin and final wear were evaluated for different piston ring coatings and methods of application. The paper will show the correlation between metallurgical and metrological parameters and efficiency of the cylinder liner-piston rings tribological system. The data from these examinations formulates required performance for transformation of abnormal and/or severe type of wear to mild processes. Presented as a Society of Tribologists and Lubrication Engineers paper at the World Tribology Congress in London, United Kingdom, September 8–12, 1997

Development of Piston-Ring for Marine Diesel Engine. Actual Engine Test Result of Piston-Ring Made from Wear Resisting Steel.

In one direction of improving the material strength of a piston-ring of a marine diesel engine, a new wear resisting steel has been made efforts to develop in the expectation that it may supersede high phosphorus gray cast iron. For the newly developed wear resisting steel (later, wear resisting steel) we carried out wear tests and scuffing tests, and analyzed its test results in comparison with those of gray cast iron. After that we manufactured piston-rings using wear resisting steel. Piston rings made from wear resisting steel were installed the actual engine, and the actual engine test was carried out for 160.8 hours. We inspected the sliding surfaces of piston-rings after 29 hours and 160.8 hours. According to the test results, the wear amount of wear resisting steel was the same or smaller than that of gray cast iron, and the sliding surfaces of piston rings were normal and no severe wear such as scuffing was observed on them.

Influence of the profile of the outer piston ring surface of a lubricant-free compressor on the gas parameters in the ring-cylinder gap

Influence of the profile of the outer piston ring surface of a lubricant-free compressor on the gas parameters in the ring-cylinder gap

A full lubrication model for rough surface piston rings

A model to stimulate the effects of one dimensional roughness of the piston ring surface on lubrication and friction is developed based on stochastic theory. The applications of the model to an actual diesel engine indicate that about 8.3%–9.4% increase in friction power loss can be expected when the rough surface ( d = 0.6 μm rather than the smooth surface is considered. The peak friction forces in compression and power stroke were predicted to occur very near the fired top dead centre (ftdc). This agrees with measured data. Some roughness contacts near the ftdc were observed.