Okay so you agree that portion of the graphs that were posted is correct. How long does it stay there and how is that any different than when it reaches zero?
You only believe the part you want to believe?
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You only believe the part you want to believe?
Which normally occurs at 70-75 degrees before and after top dead center.
Every piece of the crank, every atom of the crank, is in motion when the engine is running. Yes, agreed, it rotates in a single direction with respoetc to any reference point.
Are you referring to the energy pulses that come from each combustion event?
With constant rpm for all/any dt, it happens at 90deg.
Both. Every atom changes direction all the time, they rotate in the same direction. Only a infinite # of vectors can describe a circular rotation.
Still not sure why you want to attach the movement of the crank to the movement of the piston, they're connected, but move in different ways, one continuous, the other not.
Empire where did you go to school and what's your degree?
You can't seriously be using this as a defense of your statement
In linear reciprocating motion, I would look at the acceleration vector, which is needed to slow down and change directions. So although speed is slowing down to zero, the accelaeration vector is pointing in opposite direction of such motion, and as long as the acceleration vector is not zero, the motion is then continuous, hence the motion slows and then changes direction 180deg.
Nuclear Engineering is my degree. You?
I am. If you observe the crank motion from any ref point, and make a flux volume, the crank atoms will enter in and exit out the volume in continuous fashion, thereby telling a direction from such ref point.
Just a BSME with a minor in Chemistry. Nothing spectacular.
We know exactly what way its going at any given time (t), even when the observation is made when speed of velocity = 0, the acceleration vector also has direction. If an acceleration vector exists, it must be moving
The velocity and acceleration vectors have phase shift with respect to each other, velocity vetcor lags the acceleration vector.
Peak piston speed occurs at 70-75 degrees before and after top dead center. The small range is due to variances in the rod length in relation to the crank stroke. The peak combustion energy occurs at 16-20 degrees after top dead center and peak force to crank rotation occurs at 26-32 degrees after top dead center. The combustion energy has typically decayed to a fraction of peak pressure once it reaches 70 degrees ATDC. Peak piston speed is more important for specing the camshaft than combustion energy.
Very well then, your model includes the actual combustion events which dictate how the velocity vector changes with respect to a combustion event.
With simplified model of the translated motion (rpm's constant for any dt) max speed would be at 90deg.
I think we are now getting into real definition of zero and 0 divided by 0 (dx/dt) and mathematically undefined territory ... Given a very small dt (approaching 0) at the top of the piston, the absolute dx in one direction could be a very small positive number approaching 0 and after it does the 180°, the dx will be a very small negative number approaching 0. the perceived dx is 0 and is the sum of the two dx (one positive and one negative relative to the top of piston) but the absolute delta dx is not zero. I think that would satisfy the math ... it would be like going over the same point (right at the peak / top of piston) twice but in a different direction ... Which would lead to lack of movement at that specific moment.
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