1. 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

2. 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)

3. Power cylinder unit Cylinder liner Piston Top compression ring
Second compression ring
Oil control ring

4. Losses in the PCU
Distribution of total energy
Distribution of mechanical friction
PCU is responsible for % 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

5. 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

6. 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

7. 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.

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. Repeatability results two compression rings
Cylinder liner and piston ring holder disassembled between Assembly 1 and 2
Sampled data
Filtered data

15. 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

16. 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

17. Repeatability results

18. Results All rings mounted Varied speed Cylinder liner and oil: 80oC
Sampled data
Filtered data

19. 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

21. Thank you Markus Söderfjäll Division of Machine Elements
Luleå University of Technology
Söderfjäll, Markus, Andreas Almqvist, and Roland Larsson. "Component test for simulation of piston ring–Cylinder liner friction at realistic speeds." Tribology International 104 (2016):