Torque calculation on drive half shaft in coast downshift condition

AI Thread Summary
Calculating the torque on a half shaft during a coast downshift involves understanding the dynamics of the vehicle as it transitions from 3rd to 2nd gear while coasting. The torque experienced on the shaft can range from 1300 Nm to 1700 Nm, influenced by the clutch engagement method—gradual or sudden. Factors such as drag torque from the engine and wheel slip torque, which is approximately 830 Nm with a coefficient of friction of 0.8, also play a significant role. Additionally, it is essential to account for the force needed to accelerate the flywheel and the engine's rotating and reciprocating masses. Accurate calculations require a comprehensive understanding of these variables and their interactions.
kkd
I want to calculate the torque coming onto a half shaft in a very particular event.

The event is I let's say I am in 3rd gear and have reached my max torque zone after which I have taken my foot of the acc pedal...nw I m letting the the vehicle coast as soon as it reaches say 60% of max power rpm I downshift to 2st gear and after downshift m still not pressing the acc pedal..m just letting the vehicle drive by its momentum..

Now during my downshift as soon as I engage the clutch I will have a very high amount of torque cmng onto the shaft...
Pls guide me how to proceed to calculate this torque..!
Thanx in advance... :)
 
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As always, draw a free body diagram.
The braking torque depends on the motor characteristics.
You need to calculate how much torque is required to run the engine against a closed throttle... No easy task...
Do you know the fluid friction across the butterfly etc?
 
Thanx billy for your reply...
It is basically a fuel in injected engine...I had some some data regarding the drag torque of the engine... If I multiply that value to the gear ratios the torque which is coming is to the tune of 200 Nm per shaft..the wheel slip torque if I consider .8 coefficient of friction comes up to 830 Nm but the incident which I mentioned above the values of torque varies from 1300 Nm to 1700 Nm depending upon the way clutch is released...1300 for gradual & 1700 for sudden...
 
kkd said:
Thanx billy for your reply...
It is basically a fuel in injected engine...I had some some data regarding the drag torque of the engine... If I multiply that value to the gear ratios the torque which is coming is to the tune of 200 Nm per shaft..the wheel slip torque if I consider .8 coefficient of friction comes up to 830 Nm but the incident which I mentioned above the values of torque varies from 1300 Nm to 1700 Nm depending upon the way clutch is released...1300 for gradual & 1700 for sudden...
Also include the force needed to accelerate the flywheel and rotating/reciprocating mass of the engine.
 

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