Renault R31

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ringo
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Joined: 29 Mar 2009, 10:57

Re: Renault R31

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thisisatest wrote:my apologies:
spring=position sensitive
damper=speed sensitive
inerter=acceleration sensitive

it is different from a shock absorber in that it doesnt absorb shock. actually, it works against absorbing shock, as you effectively have a lot more unsprung weight.
Explain what you are saying. My understanding is that a damper is a damper.
An inerter is a damper as well.
You are not being clear. The thing that i circled is more than likely the reason why this vibration absorber is different than a typical damper, outside of the mercury filling.

The mass that I circled is the vibration absorber, the key point to the device, the rest of it is more or less the same function as a typical damper.
This is from what i see, scarbs hasn't posted a link to the patent, so i cannot read any more into it.
For Sure!!

timbo
timbo
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Joined: 22 Oct 2007, 10:14

Re: Renault R31

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ringo wrote:An inerter is a damper as well.
Inerter is NOT a damper. It doesn't dissipate energy.
Read this
http://www-control.eng.cam.ac.uk/~mcs/lecture_j.pdf

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dren
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Re: Renault R31

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I'm under the impression an inerter is the mechanical equivalent to a capacitor. It smoothes out fluctuations (vibrations) by storing and releasing energy.
Honda!

timbo
timbo
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Re: Renault R31

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dren wrote:I'm under the impression an inerter is the mechanical equivalent to a capacitor. It smoothes out fluctuations (vibrations) by storing and releasing energy.
Spot on=) just read the lecture -- inerter works as a capacitor, where as damper as a resistor.

PhillipM
PhillipM
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Re: Renault R31

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ringo wrote: The mass that I circled is the vibration absorber, the key point to the device, the rest of it is more or less the same function as a typical damper.
This is from what i see, scarbs hasn't posted a link to the patent, so i cannot read any more into it.
The bit you circled is just a steel shim to drive onto the bumpstops.

scarbs
scarbs
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Re: Renault R31

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Yes the part circled is just the bump stops, both to protect the Inerter and for the limit of heave travel.

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mep
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Joined: 11 Oct 2003, 15:48
Location: Germany

Re: Renault R31

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Currently I don't have the time to read the article from scarbs but just from looking on the picture I already get the idea hot the fluid J-damper works.
Actually its quite simple and similar like ones with a solid mass. This one just brings the fluid into rotation flowing around the helixes from one side to the other. As the fluid is quite heavy you get your desired characteristics.
I wonder how they adjust it. The one using a solid mass seems to be easier to adjust. Maybe they just don't adjust them.
Those bumb stops there have absolutely nothing to do with its funktion. I even wonder why they put them there because it seems to be hard to change them.

I wonder how there is anything new to discover or if I am completely wrong when I read scarbs article later. :lol:

Edit: Aaah that design is just so genious and simple. I could even rebuild one during the christmas holidays.

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ringo
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Re: Renault R31

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Those of you who claim what part of the system is the interter, can you demonstrate how it works?
Based on the information writen in the article, i don't think the fluid is the whole story.
I can do a demonstration design for you right now, showing how that mass can act as the inerter as the shaft of the piston moves. Those of you familar with laplace transforms can follow.

There a variable vibration absorbers that look just like that "bump stop".

I'm a tough cookie already, so you know i'm going to need to see some substance and numbers before i join the club. Based on my limited knowledge, the bump stop mass can act as the inerter. Based on knowledge of the moving fluid, it's not clear what it is doing exactly to absorb vibration, it is just stated.

Scarbs, you should post the link to the patent. We don't have enough information.
I'm shooting in the dark here.
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thisisatest
thisisatest
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Joined: 17 Oct 2010, 00:59

Re: Renault R31

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the thing works by pushing mercury around. the mercury exits one chamber and goes on a roller coaster ride around and around the inerter body, re-entering at the other side. they picked mercury because it's very heavy.
during shaft acceleration, the piston accelerates mercury through the tubes. the mercury's inertia provides resistance. at a constant shaft speed, the resistance should be close to zero. (i wonder about the size of the orifice for the coiled tubes, and how much resistance is created there).
it is the fluid version of the inerter that pushes a threaded shaft that in turn spins a mass. i find it easier to see how the mechanical one works, and to see how the fluid one resembles the mechanical one, than to see how the fluid one works directly. like i said, i get stuck on the port size to the coiled tube, seems to me it would provide some damping there where the mechanical one would not...
or does the mechanical one suffer from some friction on its threads, bearings notwithstanding? the article did mention frequent regreasing...

hardingfv32
hardingfv32
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Re: Renault R31

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It is simply about acceleration and decelerating the mercury. So for every time you get it flowing an effort must be made to stop it.

Where a normal shock is at zero pressure when its shaft stops, the inerter is still generating a pressure when its shaft stops because of the momentum of the mercury.

I would think they developed the liquid version because the mechanical version is under patent.

Brian

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ringo
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Re: Renault R31

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thisisatest wrote:the thing works by pushing mercury around. the mercury exits one chamber and goes on a roller coaster ride around and around the inerter body, re-entering at the other side. they picked mercury because it's very heavy.
during shaft acceleration, the piston accelerates mercury through the tubes. the mercury's inertia provides resistance. at a constant shaft speed, the resistance should be close to zero. (i wonder about the size of the orifice for the coiled tubes, and how much resistance is created there).
it is the fluid version of the inerter that pushes a threaded shaft that in turn spins a mass. i find it easier to see how the mechanical one works, and to see how the fluid one resembles the mechanical one, than to see how the fluid one works directly. like i said, i get stuck on the port size to the coiled tube, seems to me it would provide some damping there where the mechanical one would not...
or does the mechanical one suffer from some friction on its threads, bearings notwithstanding? the article did mention frequent regreasing...
Your post doesn't seem very sure. I want to learn this thing you see.

The problem is the word inerter. I am thinking of vibration absorber.
I will show the theory behind the vibration absorber, but i'll first read on the inerter and see if it's the same thing. See if i'm lost in translation.

edit:

a good read for those interested:
http://www-control.eng.cam.ac.uk/~mcs/lecture_j.pdf
need to brush up on your maths to fully appreciate it. I learned that what i was proposing was an older method to a similar problem, but the inerter is different in principle.
Hope this is good raw information for those who might want to do a little tinkering.

I am reading the first article posted by bryan as well. The thing is basically a capacitor.
That's all i was asking. There was too much techno jargon for such a straight and direct answer.
Conclusion the benefits of a capacitor in an electrical circuit should apply to a mechanical system as well.
For Sure!!

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aleks_ader
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Joined: 28 Jul 2011, 08:40

Re: Renault R31

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ringo wrote:
There a variable vibration absorbers that look just like that "bump stop".
I think this is actually the case of this inerter damper!!! To stop neceserially oscilation of the suspension after shock absorbation... This will be decrease the suspension reaction time to absorve next shock....
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna

timbo
timbo
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Re: Renault R31

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aleksandergreat wrote:I think this is actually the case of this inerter damper!!! To stop neceserially oscilation of the suspension after shock absorbation... This will be decrease the suspension reaction time to absorve next shock....
Nope. Inerter does not dissipate energy.

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aleks_ader
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Re: Renault R31

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Fluid Inerter:

Image

Being able to counteract these uncontrolled forces in a suspension will allow the tyre to main better contact with the ground for more consistent grip.

Between the terminals this translates to an inertial force which resists acceleration.

Benefits:

lightweight=> The tiny amount of fluid (MERCURY) required would be lighter than an equivalent spinning mass

Small weight and CofG=> As Inerters tend to be mounted relatively high a weight saving will aid CofG height

No problem with re-grease: easier to maintain, teams needing to strip clean and re-grease their Mechanical Inerters frequently to maintain their smooth operation.

The solution is totally legal, as set by the precedent of the mechanical Inerter being allowed to race
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna

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aleks_ader
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Joined: 28 Jul 2011, 08:40

Re: Renault R31

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timbo wrote:
aleksandergreat wrote:I think this is actually the case of this inerter damper!!! To stop neceserially oscilation of the suspension after shock absorbation... This will be decrease the suspension reaction time to absorve next shock....
Nope. Inerter does not dissipate energy.
Being able to counteract these uncontrolled forces in a suspension will allow the tyre to main better contact with the ground for more consistent grip.

That i mean! ;)
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna