Why is there a negative torque in TMD of 4 stroke engine?

Click For Summary
SUMMARY

The torque moment diagram (TMD) of a 4-stroke engine exhibits a negative loop during the suction stroke due to the pressure differential created by the piston movement. As the piston descends, it increases the volume above it, resulting in lower pressure above the piston compared to atmospheric pressure. This phenomenon is critical for understanding engine dynamics and the functioning of the TMD, which illustrates the torque produced throughout the engine cycle.

PREREQUISITES
  • Understanding of 4-stroke engine mechanics
  • Familiarity with torque moment diagrams (TMD)
  • Knowledge of pressure differentials in fluid dynamics
  • Basic principles of internal combustion engines
NEXT STEPS
  • Research the mechanics of the 4-stroke engine cycle
  • Study the role of pressure differentials in engine performance
  • Explore advanced torque moment diagram analysis techniques
  • Learn about the impact of atmospheric pressure on engine efficiency
USEFUL FOR

Engineers, automotive technicians, and students studying mechanical engineering or internal combustion engines will benefit from this discussion, particularly those interested in engine performance and dynamics.

pravi
Messages
3
Reaction score
0
In the torque moment diagram of 4 stroke engine, there is a negative loop during suction stroke. Many books state that it is due to the higher atmospheric pressure. But, I do not understand the concept. Please help me understand why there is a negative and positive loop during suction and exhaust stroke. I would also like to know the usage and working of the TMD. Please help me. Thanks.
 
Engineering news on Phys.org
Hello Pravi, it's high time you were welcomed to PF: welcome :smile: !

During the suction stroke, the volume above the piston increases and the piston has to pull in new fuel and air. If it's vertical and going down, then above the piston there is a low pressure and below atmospheric.

Did you look at a few tutorials, e.g here ?
 

Similar threads

Replies
2
Views
3K
Replies
11
Views
4K
Replies
19
Views
3K
  • · Replies 22 ·
Replies
22
Views
3K
Replies
6
Views
5K
Replies
13
Views
4K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 11 ·
Replies
11
Views
9K
Replies
9
Views
6K
  • · Replies 6 ·
Replies
6
Views
4K