Determining camshaft deceleration rate from Follower?

  • Thread starter Thread starter AmazingTrans
  • Start date Start date
  • Tags Tags
    Deceleration Rate
AI Thread Summary
The discussion centers on understanding the deceleration rate of a camshaft in relation to a motor acting as a follower, particularly in the context of maintaining torque limits. The camshaft operates at a constant speed without velocity or acceleration boundaries, while the motor's torque decreases at higher speeds. The goal is to determine a deceleration formula that keeps the motor's torque at 75% of its curve when the camshaft stops at a specific rate. The conversation also touches on regenerative braking in modern vehicles, suggesting that the deceleration rate should adapt based on speed to optimize torque delivery. There is a request for clarification on how a motor can function as a cam follower, indicating a need for a better system description.
AmazingTrans
Messages
8
Reaction score
0
I am doing this as a hobby, trying to understanding some physics calculation for camshafts and following cam s,v,a,j.
All pictures in this thread are just samples that tie to nothing much, other than just images.

p34.png

7y94hR.png


1. From the 1st image above, the camshaft (emulated digital signal) is moving at a "constant speed", and the follower (motor) has the following plot. The camshaft has no boundaries in terms of velocity, acceleration, or jerk since it is digitally emulated.

I also have included the follower (which is a motor) properties. (Yes that's a tesla S motor. =D ) As we can see, the higher the speed of the motor, the lesser torque.

If the follower/motor is running at 120 mph and only capable of "d Nm" (reduced torque),
At point #2 of the cam plot and the camshaft decided to stop at a specific rate "x".
What would the camshaft deceleration formula look like if I want the follower/motor to not exceed 75% of the torque curve at that point ?

My goal here is to use to constantly change the camshaft deceleration rate such that the follower does not ride along its torque curve all the time.
 
Engineering news on Phys.org
I just thought, another good example of this application would be like today car (Nissan) where they use regenerative braking to brake the car.
If they were to run the car at higher speed, they have limited torque at that point. I would think the controller would constantly change its deceleration rate such that the motor follows the torque curve of the motor until it reaches low speed, then it will apply higher deceleration rate (more torque) when it is at lower speed.
 
There seems to be something missing in your system description. How can a motor be a cam follower? I've done a lot of work with cams, but I've never seen anything that I would describe like this. Could you give us a sketch of the system you are talking about, please?
 
AmazingTrans said:
I just thought, another good example of this application would be like today car (Nissan) where they use regenerative braking to brake the car.
If they were to run the car at higher speed, they have limited torque at that point. I would think the controller would constantly change its deceleration rate such that the motor follows the torque curve of the motor until it reaches low speed, then it will apply higher deceleration rate (more torque) when it is at lower speed.

Torque at high speed is probably limited because max power has been reached. I'm not sure if max power is limited by the motor or battery on the Tesla.

I can't think of a reason why, under regenerative braking, the torque should be limited to exactly same curve as under power.
 
Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
Thread 'What's the most likely cause for this carbon seal crack?'
We have a molded carbon graphite seal that is used in an inline axial piston, variable displacement hydraulic pump. One of our customers reported that, when using the “A” parts in the past, they only needed to replace them due to normal wear. However, after switching to our parts, the replacement cycle seems to be much shorter due to “broken” or “cracked” failures. This issue was identified after hydraulic fluid leakage was observed. According to their records, the same problem has occurred...
Back
Top