analysis profile camshaft

[pepino81]

hello to all and thank you in advance for the answers you will give me! I'm processing an engine and I have several trees I don't know anything about except the max lift, I wanted to know how you can go back to your diagram to fit it! to think that as a boy I did it in the shop and now I don't remember anything! The engineering degree burned my brain....

 

[tortellino]

I think you're wondering how the cam profile is.

then, you have to know first of all the progress of the valve accelerations (usually it is at constant accelerations or a sinusoidal trend).
then you also need to know the width of the rest angle.

integrate the first time and find the speeds: of course the speed at the beginning of the hug angle is nothing.

I have determined the trend of speed and the first constant of integration.

I mean a second time and I impose that the rise I want.
I got the lift diagram.

 

[MBT]

hello to all and thank you in advance for the answers you will give me! I'm processing an engine and I have several trees I don't know anything about except the max lift, I wanted to know how you can go back to your diagram to fit it! to think that as a boy I did it in the shop and now I don't remember anything! The engineering degree burned my brain....

Do you physically have trees?
So... mount them on the counter, a comparison, a goniometer, paper, pen and squid!
azzeri goniometro and comparison on the lowest point of the cam
detect every 5 degrees the value read from the comparator, until you complete the cam
carry all points detected in excel or autocad and you have your raised diagram!
from there, then, or with graphic method or mathematical method, you can calculate speeds, accelerations etc.

 

[PierArg]

Do you physically have trees?
So... mount them on the counter, a comparison, a goniometer, paper, pen and squid!
...

I would prefer the squid!:biggrin:

apart from the jokes... I would have done every 10th. Are the 5th imposed by any rule or experience?
Obviously everything is normal that affects accuracy.

 

[MBT]

If you have to break the boxes... it is worth breaking them well!

in its time (1994) I had made a similar relief on the cams of a car, with the cams still mounted on the motor
I had made the reliefs every 10th, but the diagram was a little "gradinesco". . .
Maybe every 5th will be sweeter, especially if they are "sports" cams a little pushed

 

[PierArg]

. .
I had made the reliefs every 10th, but the diagram was a little "gradinesco". . .
Maybe every 5th will be sweeter, especially if they are "sports" cams a little pushed

:biggrin:...so you were also "seduced" by 10 and its multiples!

 

[cacciatorino]

You should re-create the prop scheme to see what the valve actually does from your cam: is there a barbell in between? a bat?
ok as mbt said for the use of the comparator, but what you have to detect is the movement of the valve rather than that of the naked and raw profile: There is a nice difference between the motion of the point of the comparator and that of the real piattello of the pointer (varian the point of contact and the angle of pressure), not to mention the situation with balancer.

I think then that the laws of motion are polynomial (grade 5 in general, so also acceleration has a trend with continuous variation, without jumps that would harden vibrations and ticking).

 

[pepino81]

hi guys now I remembered what I did, exactly as written by mtb, every five degrees of rotation I checked the ups and then I compared with some tables I had at the time available to try to understand the diagram...of course the tables were of trees that we already knew the diagram...for which if the tree did not fall in these tables, made by him according to all the trees he knew, I remember that the old prepared crisis went in.

 

[MBT]

You should re-create the prop scheme to see what the valve actually does from your cam: is there a barbell in between? a bat?
ok as mbt said for the use of the comparator, but what you have to detect is the movement of the valve rather than that of the naked and raw profile: There is a nice difference between the motion of the point of the comparator and that of the real piattello of the pointer (varian the point of contact and the angle of pressure), not to mention the situation with balancer.

I think then that the laws of motion are polynomial (grade 5 in general, so also acceleration has a trend with continuous variation, without jumps that would harden vibrations and ticking).

bhe, just the objection, but...
many cars, today, have the valves controlled directmetne from the camshaft (with the interposition of the only bat), without use of props
Moreover, the deformations and changes of motion imposed by the pointer are "costant", so what really makes the difference is only the cam
having several cams, it is advisable to detect them and compare them, excluding the analysis, for now, the point.

 

[cacciatorino]

many cars, today, have the valves controlled directmetne from the camshaft (with the interposition of the only bat), without use of props

I think things are different even in the attics with piattello, do the checks with the comparison directly on the cam serves only to understand the starting and end points of the ramps, but it does not tell us anything about the profile of the ramp.

Moreover, the deformations and changes of motion imposed by the pointer are "costant", so what really makes the difference is only the cam
having several cams, it is advisable to detect them and compare them, excluding the analysis, for now, the point.

I don't follow you....

 

[MBT]

♪
Maybe I say you're lying...
you are perfectly right about the fact that there are differences between the motion detected with a tactor and the actual one of the valve.
to be extremely lazy, the motion detected "a firm" will differ from that "in motion" because of all dynamic components
what I wanted to say is that, if the purpose is to evaluate which cam mount, an analysis of the profile detected at the cam can be enough
this because the deviation between what is detected and what actually happens can be considered "constant" because the point is always the same.
However, once the profile of the cam is detected and knowing the geometry of the contact point (plate or props) it should be possible to calculate the motion of the valve itself

 

[PierArg]

...what I wanted to say is that if the purpose is to assess which cam mount, an analysis of the cam profile can be enough
this because the deviation between what is detected and what actually happens can be considered "constant" because the point is always the same.
...

I think so.

@caccia: isn't it like having two reference systems placed at different points but of which we know the matrix/vector of movement?
in this case the latter is the function of the shape of the spike. Right?
or am I losing my mind?