How to use piezo sensor NVH ?

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How to use piezo sensor NVH ?

Postby tode » Wed Sep 23, 2015 8:11 pm

Slowly I try to enter the world NVH, is not very easy, and I begin with the acquisition of signals only on ok engines , to understand what frequencies and amplitudes are correct, I wanted to ask you, who is more experienced than me, what it means to the symbols X and Y on the sensor and how to exploit them, I have already noticed that the value varies in amplitude of the signal, but I think that a piezo sensor has only one direction to read vibrations, or Pico has a dual sensor?
How to use piezo sensor NVH?
Greetings
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Re: How to use piezo sensor NVH ?

Postby Belet » Thu Sep 24, 2015 12:55 am

Tode, that's what I want to ask.
Looking forward to the replies.
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Re: How to use piezo sensor NVH ?

Postby Steve Smith » Thu Sep 24, 2015 11:35 am

Hello and thank you for the posts.

The accelerometer included in the NVH kit is in fact a 3 axis device capable of measuring vibration in 3 directions X, Y, and Z or to put this another way, X axis vibration Fore/Aft, Y axis vibration Vertical, and Z axis vibration Lateral.

ACCELEROMETER AXIS EXPLAINED.jpg


However all three axis are summed together inside the NVH interface box in such way as to give the end user an overview of all axis. Here then there is no rejection of a particular vibration in a specific axis/direction, everything is accounted for.

The real beauty of such a feature is that with one scope channel, the end user will pick up a vibration present even when the direction of vibration is unknown.

For example, mounting the accelerometer vertically on a chassis member will detect all vibrations in all axis/directions, as will mounting the accelerometer horizontally on the same chassis member.

A point to note here is the accelerometer included in the NVH kit is not a piezo device as such accelerometers are expensive and delicate.

The accelerometer included in the NVH kit is a robust MEMS device mounted in such a fashion as to detect all vibrations (3 axis) and return a signal to the interface unit relevant to the detected vibrations.

(The interface is responsible for accelerometer power and data conversion).

We no longer have to worry about orientation when measuring vibrations and the inherent fragility of the Piezo accelerometers given the MEMS unit has a shock survivability of 10, 000 g

I hope this helps, take care........Steve
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Re: How to use piezo sensor NVH ?

Postby tode » Thu Sep 24, 2015 7:52 pm

Many thanks Steve.

I went to see what "sensors MEMS accelerometers" I did not know this fantastic technology, but thanks to this technology, it would be better able to understand from which coordinated the vibration arrives?
I think that in the engine compartment direction of the vibration does not have much importance, while in the passenger compartment, to know if the vibration from the forward/backward, under/above, or right/left ?
Or in a car you might create too many variables that make troubleshooting more difficult?

regards
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Re: How to use piezo sensor NVH ?

Postby Steve Smith » Fri Sep 25, 2015 10:10 am

Hello Tode and thank you for the post

Could you take a look here at,
topic10841.html?hilit=accelerometer

You may have already been through this post but what you mention is most certainly correct about the value of highlighting not only the vibration level, but the direction of vibration (Especially cabin vibration)

Not sure how best to word this but here goes:

Testing vibration levels (AND DIRECTION) is already in place here at Pico, individually measuring all 3 axis (X, Y and Z) along with some other features

I have it on good authority this could well be available in a beta version in the near future but have no more information to date.

Rest assured as soon as we can we will post the relevant information along with supporting tutorials, screen shots and captures.

I hope this helps, take care.......Steve
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