Friction loss in an internal combustion engine largely depends on elastohydrodynamic lubrication. The piston compression ring is a contributor to such parasitic losses in the piston subsystem. The complex elastodynamics of the ring are responsible for the transient and regime-altering film that affects the elastohydrodynamic lubrication of the ring liner contact conjunction. The current paper will discuss the ring radial, lateral deformation, and axial twist, and its effect on the film profile of the compression ring and its subsequent effect on tribological characteristics like elastohydrodynamic pressure, friction, and lubricant. A finite difference technique is used to solve the elastohydrodynamic issue of elastodynamic piston compression by introducing the elastodynamically influenced film thickness into the lubrication model. The results show that consideration of the elastodynamics predicts a 23.53% reduction in friction power loss in the power stroke due to the elastodynamic ring compared to the rigid ring. The elastodynamic effect improves the lubricant oil flow into the conjunction. A finite element simulation predicts a von-Mises stress of 0.414 N/mm2, and a maximum deformation of 0.513 µm at the core and coating interface is observed at the ring–ring groove contact. The sustainability of EHL in this case largely depends on the ring–liner elastodynamics.
Key Questions
1. What is elastohydrodynamic lubrication?
Elastohydrodynamic lubrication (EHL) is a form of lubrication that occurs in high-pressure, non-conforming contacts where elastic deformation of the surfaces significantly affects the film thickness and pressure distribution.
2. How does piston ring elastodynamics affect engine friction?
The paper shows that considering piston ring elastodynamics predicts a 23.53% reduction in friction power loss during the power stroke compared to a rigid ring model. This demonstrates the importance of accounting for ring deformation in engine friction analysis.
3. What method is used to solve the elastohydrodynamic problem?
A finite difference technique is used to solve the elastohydrodynamic problem by incorporating the elastodynamically influenced film thickness into the lubrication model.
4. What are the key findings from the finite element simulation?
The finite element simulation predicts a von-Mises stress of 0.414 N/mm2 and a maximum deformation of 0.513 μm at the core and coating interface of the ring-ring groove contact.
5. How does elastodynamics affect lubricant oil flow?
The study finds that the elastodynamic effect improves lubricant oil flow into the ring-liner conjunction, which can impact the overall lubrication performance.
