PPP measurement (was Knock module for MS3)

[piledriver]

Just registered that they are only 15khz bandwidth, ~useless for knock?
Hopefully some OEM will want similar for gasoline engines and they'll design one w/o the rod transmitting the pressure.

Current use is on diesels... low RPM.
Both the 1st gen Beru glow plug an the new CPOS units share the same diaphragm + long rod pressure coupling setup, OK for pressure at lower speeds, likely provides much needed temperature isolation.

What would the effective RPM limit be with only 15 khz bandwidth for pressure measurement?

[subwoofer]

BW should be fine, knock ringing is usually 6-9kHz, right?

The brief said it was intended for petrol engines too, and with 15kHz of bandwidth you should be able to monitor > 150kRPM for PPP, I really don't think it will be a problem.

[nuvolarossa]

BW should be fine, knock ringing is usually 6-9kHz, right?

many I know use this calculator
http://www.phormula.co.uk/KnockCalculator.aspx
as long as your cylinder bores diameter is bigger than 39mm, you should be fine about knock frequency, I mean below 15kHz

EDIT: oh, I misread, you were speaking about BW...

[piledriver]

... to accurately sample the signal the bandwidth would need to be 4-10X higher than the center frequency, but perhaps I am overthinking it. Would still work for PPP with little more than a peak detection routine.

Looks like `14 mercedes have these, no part#/price yet possibly dealer only still.

[subwoofer]

You are thinking in terms of time discrete systems, 15kHz of analog BW is plenty...

[Hey_Allen]

Looks like Daimler is now using a 0-5v pressure-only sensor and seperate ceramic glow plugs, anyone have a part# and vehicle app?

As a MB owner who does my own service, I have purchased access to the online parts catalog for the whole international line, and could not find it in any of the cars that I checked.

The newest was a 2014(?) Sprinter, and it still has donut knock sensors, installed between cylinder pairs.

If anyone gets hard information as to what models should have it, I can look, but I'm not having much luck just poking about. This is also hindered by generally needing a VIN for a vehicle of the type that I am looking for parts from.

Carry on with the discussion, though!

[piledriver]

Diesel cars first, possibly the Bluetec Bin5 and EU6 flavors, IIRC the trucks still get some slack emissions wise.

They LOOK like and probably go ~ where or next to the glow plugs would or adjacent to the spark plug if they are using them on gas models.
allegedly there is an 8mm and 10mm version, the buisiness end is probably ~5-ish mm diameter.

Is it an accomplishment if you hijack a thred so thoroughly the mods rename it?

[MS2tester]

arent ion sensing ignition coils not just around the corner?
http://delphi.com/pdf/techpapers/2013-01-0354.pdf
http://www.delphi.com/manufacturers/aut ... /igncoils/

[piledriver]

arent ion sensing ignition coils not just around the corner?
http://delphi.com/pdf/techpapers/2013-01-0354.pdf
http://www.delphi.com/manufacturers/aut ... /igncoils/

Ion sensing ignition coils have been "just around the corner" for 20+ years.
I have a set of Delphi ion sense coils (HD Twincam) I ran for awhile and pulled some traces from, they DO work.
They have serious limitations, and require extensive signal conditioning to be useful at all, and only really work near WOT.
(The SNR is horrible at cruise, for example, utterly useless)

They make for great knock sensors (at high loads), and that is generally what OEMs have actually used them for.

The pressure sensors put out 0-5v, and measure pressure. Period. Nice clean signal from all data available.
Actual dynamic range is TBD, as if they work at idle/cruise loads. Hoping to find out RSN if I can lay my hands on one..

[subwoofer]

Resurrecting this thread, just found these sensors from Kistler: https://www.kistler.com/no/en/applicati ... s_6054_b_r

Haven't asked them for cost yet, but it should be possible to retrofit them into a lot of heads. Fits in an M5 thread, meant to take a beating too. You have to register to download the pdfs, but no ill effects (yet) from doing that.

[piledriver]

Coming from Kistler FIA approved expect it to cost $1k each and require another $1K external amplifier.

Could be done cheap RFN if you made an adapter for the Beru pressure sensing glow plugs, 0-5v output.
Its just a shame when the CPO (cylinder pressure only) units exist.

I'll try a little more Googling.

[subwoofer]

You are probably right. We need to find a source for the Beru CPO sensors and write some DSP code to find true PPP.

[piledriver]

I sent another email to sensata begging for an OEM part# or at least application.

They are probably made by Beru, sensata only owns the patent/design... i think.

I guess i should hit up BERU... perhaps one of out European listers has a connection?

I have worked at the TI fab/know folks where the actual MEMS internal sensor and IC are probably made... hmmm...

[subwoofer]

Beru is "BorgWarner Emissions" in terms of OEM parts, Beru Federal-Mogul is the aftermarket brand. I am in Europe, but not very well connected in the car parts industry. Once we figure out an engine code the sensor actually sits in everything should become a lot easier.

[masterx81]

I see some of the PSG glow plugs with only 5khz of bandwidth.
http://beru.federalmogul.com/en-gb/node/262

[Kristof]

Audi is using them in several TDI engines.
Here are some OE numbers:

03L 905 061 D
03L 905 061 E
03L 905 061 F

[subwoofer]

We are sort of one step closer then, but it is the CPOS sensors we really want. Anyone with connections into the Mercedes-Benz world who have any bearing on this? If we just find the engine they are used on, we should be able to work out the rest.

[piledriver]

We are sort of one step closer then, but it is the CPOS sensors we really want. Anyone with connections into the Mercedes-Benz world who have any bearing on this? If we just find the engine they are used on, we should be able to work out the rest.

IIRC some of the newer diesels are candidates.
The PSGs are metal glow plugs, the ceramic plugs are much more reliable, so they dropped the sensor glow plug, use a std ceramic glow plug and a pressure-only sensor.

[subwoofer]

Interesting read: https://www.kistler.com/?type=669&fid=42&model=download

[piledriver]

Fascinating, but at $3K per sensor plus impedance matching amp and >$85K for the whole setup I think it will have to wait at least until payday.

I suspect the 0-5v output of the CPOS units could easily be easily conditioned and put to use feeding the knock module, providing a potentially clean signal for that use immediately.

I have an 8 channel DAQ setup that can do 100Khz (shared) sampling, but some of the sound card setups out there have phenomenal capabilities, esp for relative measurements and at a killer price.

Heck, i kept an old Athlon motherboard with a (short lived) NVidia audio chip that can sample 4 channels of 16 bit audio at 480KHz each. (10X oversample 48KHz audio)
That would be pretty low end today, some of the serious setups can do 8 or more channels of 24 bit at 96 KHz, with some level of oversampling.
Getting the data to the harddrive fast enough is more of an issue.