Engine Lubrication System Lecture Notes

Introduction

• The internal combustion engine contains many friction parts.
• Friction causes wear and overheating.
• Lubrication system reduces friction and removes heat.
• Lubricant delivered to all friction parts:
  • Vital parts fed with lubricant under pressure.
  • Others rely on gravity and splash feeds.

Engine Lubrication Cycle

1. Oil Filling:

   • Engine filled with motor oil.
   • Oil drains into the oil sump via timing drive cavity and dedicated channels.
   • Stored in the oil sump with a dipstick and oil strainer.

2. Engine Start:

   • Activates the oil pump, drawing oil and creating pressure at outlet.
   • Pump options: chain drive from crankshaft, gear drive, or direct mount.
   • Pressure relief valve controls pressure limit and opens if exceeded.

3. Oil Pump Function:

   • Different types: external/internal gear meshing, gerotor pump, variable discharge oil pump.
   • Pressurized oil cleaned by oil filter from metal dust and impurities.
   • Bypass valve allows oil passage if filter clogged.

4. Oil Distribution:

   • Cylinder Block's Oil Gallery:
     • Oil lubricates crankshaft's main journals and main bearings under pressure.
     • Coating minimizes friction.
   • Crankshaft Channels:
     • Oil lubricates rod journals and connecting rod bearings.
     • Rotation of crankshaft sprays oil, lubricating cylinder walls, pistons, and timing drive.
   • Cylinder Head Oil Gallery:
     • Oil reaches camshaft journals, lubricating timing drive, cams, tappets, and valve stems.

5. Oil Recirculation:

   • Splashed oil runs down to oil sump and cycle restarts.

System Components

• Oil Pressure Sensors:
  • Control system's functioning, placed in different parts, upstream/downstream of filter.
  • Low oil pressure triggers dashboard warning light.
• Complex Systems:
  • May include oil temperature sensors, oil level sensors, cooling radiators.
  • Improvements like extra oil passages, oil jet nozzles.
  • Lubrication needed for turbocharger and some control functions.

Oil Control Mechanisms

• Pistons have oil control rings to prevent excess oil in combustion chamber.
• Valve stem seals prevent excess oil entry through valve stem.
• Gaskets and oil seals prevent oil leakage.

Maintenance

• Regular oil changes are crucial to prevent engine wear due to contaminated oil.
• Dirty oil leads to severe engine wear.

Conclusion

• Regular maintenance and understanding of the lubrication system are essential for engine longevity.

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• Closing: Until next time.