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Display Signal over angle of Crankshaft

Hi there,

 

I'm currently working on my bachelor thesis and I want to display the combustion pressure over the crankshaft angle, not overtime.

In LabView I generated a crankshaft angle signal by the signal of the crankshaft sensor. The result is a signal increment by 6° up to 720°, for every rotation of the engine (see attachment). 

Now I want to use this signal as X-axes for my combustion pressure signal.

The problem is that my current resulting X-axe stops at 720° and overlaps the following Y-values.  

In attachment is a sketch of want I want to gain. 

 

I'm open to resolutions in LabView or DIAdem. 

 

May you can help me 🙂 

 

Thanks 

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Hi Ruffy,

 


@Ruffy_LR wrote:

Now I want to use this signal as X-axes for my combustion pressure signal.

The problem is that my current resulting X-axe stops at 720° and overlaps the following Y-values.  


When you want to show rising X values then the X values should be rising!

You may "unwrap" the X values to go from 720 to 780, 840, … instead of 720 to 60, 120…

 

Btw.:

Why did you delete the file suffix for that JPG image in the archive?

Please use default ZIP archives instead of proprietary file fomrats like RAR!

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
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Hi, GerdW 

Thanks for the fast response.

 


@GerdW wrote:  

When you want to show rising X values then the X values should be rising!

You may "unwrap" the X values to go from 720 to 780, 840, … instead of 720 to 60, 120…


I could do that but that's not what I want to achieve. In engine engineering, it is standard to refer the engine data to the current position of the engine, given by an angle between 0° - 720° (720° = 2 rotations, because of the 4 strokes).

 

 


@GerdW wrote:

 

Btw.:

Why did you delete the file suffix for that JPG image in the archive?

Please use default ZIP archives instead of proprietary file fomrats like RAR!


Sorry for that I  did a reupload in this command. 

 

Best regards,
Ruffy

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Hi Ruffy,

 


@Ruffy_LR wrote:

Hi, GerdW 

Thanks for the fast response.

 


@GerdW wrote:  

When you want to show rising X values then the X values should be rising!

You may "unwrap" the X values to go from 720 to 780, 840, … instead of 720 to 60, 120…


I could do that but that's not what I want to achieve. In engine engineering, it is standard to refer the engine data to the current position of the engine, given by an angle between 0° - 720° (720° = 2 rotations, because of the 4 strokes).


I know that, I also do measurements related to crank angle. But in my experience we always plot from -180° to +180° for a steam engine.

And plots from combustion engines usually (IMHO) use the plot range from -360° to +360° - without appending the next 4 strokes after the first 4 strokes. All I have seen is a display of exactly 4 strokes…

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
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I haven't done engine measurements but have been in a lot of discussions about them.

 

To plot analog sensors vs. crank shaft angle, it's *usually* easiest to use the crank angle encoder as an *external sample clock* for the AI task.  Often, some kind of TDC signal is also used as a trigger to establish a starting reference angle.

 

In this scheme, the angle is *implied* by the sample # of the AI data.  In your case, it would be 6 degrees per sample.  Then you can just do a modulo operation to make the angle stay within the 0-720 range.

 

 

-Kevin P

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