Standard Test Method for Conducting Friction Tests of Piston Ring and Cylinder Liner Materials Under Lubricated Conditions

Importancia y uso:

5.1 The efficiency and fuel economy of spark ignition and diesel engines is affected in part by the friction between moving parts. Although no reliable, in situ friction measurements exist for fired internal combustion engines, it has been estimated that at least half of the friction losses in such engines are due to those at the ring and liner interface. This test method involves the use of a reciprocating sliding arrangement to simulate the type of oscillating contact that occurs between a piston ring and its mating cylinder bore surface near the top-dead-center position in the cylinder where most severe surface contact conditions occur. There are many types of engines and engine operating environments; therefore, to allow the user the flexibility to tailor this test to conditions representative of various engines, this standard test method allows flexibility in selecting test loads, speeds, lubricants, and durations of testing. Variables that can be adjusted in this procedure include: normal force, speed of oscillation, stroke length, duration of testing, temperature of testing, method of specimen surface preparation, and the materials and lubricants to be evaluated. Guidance is provided here on the set-up of the test, the manner of specimen fixturing and alignment, the selection of a lubricant to simulate conditioned oil characteristics (for a diesel engine), and the means to run-in the ring specimens to minimize variability in test results.

5.2 Engine oil spends the majority of its operating lifetime in a state that is representative of use-conditioned oil. That is, fresh oil is changed by exposure to the heat, chemical environment, and confinement in lubricated contact. It ages, changing viscosity, atomic weight, solids content, acidity, and chemistry. Conducting piston ring and cylinder liner material evaluations in fresh, non-conditioned oil is therefore unrealistic for material screening. But additive-depleted, used oil can result in high wear and corrosive attack of engine parts. The current test is intended for use with lubricants that simulate tribological behavior after in-service oil conditioning, but preceding the point of severe engine damage.

Subcomité:

G02.50

Referida por:

G0115-10R18, G0206-17R21E01

Volúmen:

03.02

Número ICS:

27.020 (Internal combustion engines)

Palabras clave:

cylinder liner; diesel oil; friction; liquid lubricant; piston ring;