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rrowe
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- TL;DR Summary
- While trying to simulate the physics of a Toyota Camry, my values for torque during acceleration seem to be nigh impossible when compared to the car's specified maximum torque.
I'm trying to simulate the physics of a Toyota Camry during acceleration with a time granularity of 100ms. My simulated conditions are as follows:
m = 1590 kg
v = 17 m/s
a = 1.5 m/s2
η (transmission efficiency) = 0.85
rwheel = 0.35 m
Fdrag = 100 N
Ffriction = 260 N
Faccel = 1590 kg × 1.5 m/s2 = 2400 N
Ftotal = 100 N + 260 N + 2400 N = 2760 N
The car is in 4th gear with a ratio of 1.46 and a total differential gear ratio of 2.8. This yields a combined effective gear ratio G = 1.46 × 2.8 = 4.088.
I've been operating under the assumption of perfect road traction, yielding the equation:
ωengine = Gωwheel
I've been using many of the equations from the Engineering Toolbox. Specifically, here I'm using equation (3) from Car - Required Power and Torque. Rewritten using my naming conventions and solving for torque:
τengine = Ftrwωw/ωeη
Given the relationship between angular velocity above, I know ωw/ωe = 1/G. This then yields:
τe = Ftrw/Gη
When I solve for torque given the conditions stated, I get:
τe = 2760 N × 0.35 m / (4.088 × 0.85) = 278 N⋅m
The specifications list the maximum torque output of the Camry as 184 lb ft ≈ 250 N⋅m. How is it possible that I'm exceeding the maximum torque for this vehicle while accelerating at such a relatively leisurely rate?
m = 1590 kg
v = 17 m/s
a = 1.5 m/s2
η (transmission efficiency) = 0.85
rwheel = 0.35 m
Fdrag = 100 N
Ffriction = 260 N
Faccel = 1590 kg × 1.5 m/s2 = 2400 N
Ftotal = 100 N + 260 N + 2400 N = 2760 N
The car is in 4th gear with a ratio of 1.46 and a total differential gear ratio of 2.8. This yields a combined effective gear ratio G = 1.46 × 2.8 = 4.088.
I've been operating under the assumption of perfect road traction, yielding the equation:
ωengine = Gωwheel
I've been using many of the equations from the Engineering Toolbox. Specifically, here I'm using equation (3) from Car - Required Power and Torque. Rewritten using my naming conventions and solving for torque:
τengine = Ftrwωw/ωeη
Given the relationship between angular velocity above, I know ωw/ωe = 1/G. This then yields:
τe = Ftrw/Gη
When I solve for torque given the conditions stated, I get:
τe = 2760 N × 0.35 m / (4.088 × 0.85) = 278 N⋅m
The specifications list the maximum torque output of the Camry as 184 lb ft ≈ 250 N⋅m. How is it possible that I'm exceeding the maximum torque for this vehicle while accelerating at such a relatively leisurely rate?