Display Signal over angle of Crankshaft

[Ruffy_LR]

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 

[GerdW]

Hi Ruffy,

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@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.  

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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!

[Ruffy_LR]

Hi, GerdW 

Thanks for the fast response.

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@GerdW wrote:  

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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

[GerdW]

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).

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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…

[Kevin_Price]

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