Frictional mechanical clutch slip(dry clutch)

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SUMMARY

The discussion focuses on calculating heat loss during the engagement of a frictional mechanical clutch, specifically a dry clutch, with an input power of 50 kW over a 1-second engagement period. The slip of the clutch decreases linearly with time, and the participant seeks to understand the relationship between clutch slip and time, particularly whether the slip equals 1 at the start of engagement. The equations provided include the slip as a function of engine speeds and a proposed equation for slip over engagement time, which requires clarification on the initial conditions and constants involved.

PREREQUISITES
  • Understanding of frictional mechanics and clutch operation
  • Familiarity with basic calculus and integration techniques
  • Knowledge of power and energy concepts in mechanical systems
  • Experience with clutch slip dynamics and their impact on performance
NEXT STEPS
  • Research the principles of heat loss in mechanical systems
  • Study the integration of power loss over time in clutch engagement
  • Explore the dynamics of clutch slip and its effect on vehicle acceleration
  • Investigate energy transfer efficiency in friction clutches under varying throttle applications
USEFUL FOR

Mechanical engineers, automotive technicians, and students studying vehicle dynamics or clutch systems will benefit from this discussion, particularly those interested in optimizing clutch performance and understanding energy loss during engagement.

marellasunny
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During the short period of engagement of the friction clutch(say t=1sec),energy is obviously lost as heat.I've been asked to calculate this loss of heat by my teacher.

I've been given:
1.Input power(engine)= 50kW
2.Slip decreases linearly with time
3.Engagement process time,t=1sec

Now,I know how to go about solving the problem. It involves integration of the following eq.:

$$Heat loss=\int_{0second}^{1 second}P_{loss}.dt$$

But,the question is related to the slip of the clutch.Is the slip of the clutch equal to 1 at time t=0(i.e when I start releasing my foot from the clutch pedal and the pressure plate just starts to scrape the flywheel plate)? So,if I were to draw a graph of the slip 's' on the y-axis and time of engagement 't' on the x-axis,I would be drawing a straight line with a negative slope. Also,would the clutch slip when its fully engaged?

This is the equation of slip as a function of engine speeds(THIS I UNDERSTAND):
$$slip=\frac{n_{engine}-n_{output/clutch pressure plate}}{n_{engine}}$$

This is the equation of the slip as a function of the engagement time(I DO NOT KNOW WHAT TO PLUG IN HERE):
$$s=-\frac{ds}{dt}t+c$$

s-slip
c-intercept on slip axis (IS c=1??)
 
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marellasunny said:
Is the slip of the clutch equal to 1 at time t=0?
For the slip equation you wrote, slip = 1 if the car is not moving. I don't know how this helps in calculating heat loss.

An alternative would be to calculate energy output from the engine versus energy gained by the car from initial start with clutch slipping to the time when the clutch stops slipping. With light throttle application and clutch slippage only until a relatively slow speed, the energy loss would be small. With heavy throttle application and clutch slippage until high speed, the energy loss would be much greater.
 

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