A New Test Rig for Simulation of Piston Ring Friction Markus Söderfjäll, Andreas Almqvist, Roland Larsson Tribodays 2016 Division of Machine Elements, Luleå University of Technology, Sweden
Introduction Heavy duty truck Diesel engine 40l/100km Worldwide: 550 billion liters / year 1 Worldwide: 180 billion liter / year used to overcome friction 1 1 Holmberg, K. Global energy consumption due to friction in trucks and buses. Tribology International 78, 94 – 114 (2014)
Power cylinder unit Cylinder liner Piston Top compression ring Second compression ring Oil control ring
Losses in the PCU Distribution of total energy Distribution of mechanical friction PCU is responsible for 1.1-6.8% of the total losses in a heavy duty diesel engine Distribution of piston ring and connecting rod friction Distribution of piston ring assembly friction Richardson, 2000, Review of power cylinder friction for diesel engines
Reduction of piston ring friction Reduced ring tension (𝐹 𝑛 ) Rings will conform less to liner Increased oil consumption Increased blow by Combined with reduced out of roundness Modified tribology (µ) Surface roughness / texture Viscosity Ring land profile Evaluation of concepts Numerical simulation models Easy to change geometries and parameters Study effects in detail Test rigs Validation of numerical simulation models 𝐹 𝑓 =µ⋅ 𝐹 𝑛
https://en.wikipedia.org/wiki/Engine_test_stand Full engine tests Methods Motored Strip down method Fired IMEP – BMEP Floating liner Direct measurement of friction Advantage Real engine components Disadvantages Expensive Time consuming https://en.wikipedia.org/wiki/Engine_test_stand
Component test rigs Sections of cylinder liner / piston rings Ozgen Akalin and Golam M Newaz. A new experimental technique for friction simulation in automotive piston ring and cylinder liners. Technical report, SAE Technical Paper, 1998. Component test rigs Sections of cylinder liner / piston rings Advantages Variable load Fast replacement of specimens Disadvantages Relatively low speeds Clamping of piston ring Machining of components Difficult to align NW Bolander, BD Steenwyk, F Sadeghi, and GR Gerber. Lubrication regime transitions at the piston ring-cylinder liner interface. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 219(1):1931, 2005.
Objectives for test rig developed in this work Realistic engine speeds Low vibration crank device Use standard piston rings and cylinder liner Mounting of piston rings similar to real engine Direct measurement of piston ring friction Fast replacements of specimens Oil supply similar to real engine Heated cylinder liner and oil
Objectives for developed test rig Inline six cylinder crank device Realistic engine speeds Low vibration crank device Use standard piston rings and cylinder liner Mounting of piston rings similar to real engine Direct measurement of piston ring friction Fast replacements of specimens Oil supply similar to real engine Heated cylinder liner and oil
Objectives for developed test rig Realistic engine speeds Low vibration crank device Use standard piston rings and cylinder liner Mounting of piston rings similar to real engine Direct measurement of piston ring friction Fast replacements of specimens Oil supply similar to real engine Heated cylinder liner and oil
Schematic view of test rig Heated oil tank Oil pump Electric motor Base crank device Piston ring holder Connecting rod Oil nozzles Load cells Linear bearing Heating elements Thermocouples Test cylinder foundation Balancing masses Test cylinder liner Angular position sensor Tire coupling
Specification 90 mm stroke <2200 RPM (1500 RPM) Floating liner type friction measuring technique Heated oil and cylinder liner (~80oC) Data acquisition: Friction force Crank position Temperature
Testing the repeatability of the test rig Speed: 1200 RPM Cylinder liner and oil: 80oC Different ring set-up: All rings Two compression rings Oil control ring Disassembly and reassembly of components Cylinder liner Top compression ring Second compression ring Oil control ring Piston
Repeatability results two compression rings Cylinder liner and piston ring holder disassembled between Assembly 1 and 2 Sampled data Filtered data
Repeatability results oil control ring Cylinder liner and piston ring holder disassembled between Assembly 1 and 2 Only piston ring holder disassembled between 1, 1.1, 1.2 and 1.3 Sampled data Filtered data
Repeatability results all rings Cylinder liner and piston ring holder disassembled between Assembly 1 and 2 Only piston ring holder disassembled between 1 and 1.1 Sampled data Filtered data
Repeatability results
Results All rings mounted Varied speed Cylinder liner and oil: 80oC Sampled data Filtered data
Conclusions New test rig/method has been developed Good repeatability Oil control ring was proven to starve compression rings Performance of TLOCR is significantly affected by the assembly
Thank you Markus Söderfjäll Division of Machine Elements Luleå University of Technology markus.soderfjall@ltu.se Söderfjäll, Markus, Andreas Almqvist, and Roland Larsson. "Component test for simulation of piston ring–Cylinder liner friction at realistic speeds." Tribology International 104 (2016): 57-63.