Question

Four-Stroke Engine: Components & Operation
Which of the following are two functions of piston rings?
O Hold combustion pressure in and transfer heat from the cylinder wall to the oil
O Transfer heat from the piston to the cylinder wall and hold in combustion pressure
O Retain as little oil as possible in the crankcase and keep the piston centered in the cylinder
O Make sure the wrist pin does not fall out and keep the piston in line

Answer 1

In a four-stroke engine, piston rings serve important functions related to the engine's operation. Two key functions of piston rings are: 1. **Hold combustion pressure in and transfer heat from the cylinder wall to the oil:** Piston rings help seal the combustion chamber during the power stroke, preventing the escape of high-pressure gases into the crankcase. This containment of combustion pressure ensures optimal power generation within the cylinder. Additionally, piston rings aid in transferring excess heat from the cylinder walls to the engine oil, helping to regulate temperature and prevent overheating of components. 2. **Transfer heat from the piston to the cylinder wall and hold in combustion pressure:** Another crucial role of piston rings is to facilitate the transfer of heat from the piston to the cylinder walls. This process helps in maintaining uniform temperatures within the engine, preventing hot spots that can lead to engine damage. Furthermore, piston rings play a vital part in retaining the combustion pressure within the cylinder during the power stroke, enabling efficient energy conversion within the engine. By performing these functions effectively, piston rings contribute to the overall performance, durability, and efficiency of the four-stroke engine.