EAS spurious inputs

wammers · Feb 24, 2015

Castor said:
On page 6 - the so-called "hit & drop" waveform. Entirely avoidable, unnecessarily complicated and inherently unreliable.
The valvery design is just wrong in so many ways I don't know where to start. it wouldn't be so bad if it were not for the fact that cheapo off the peg SOV's would have done just fine...

Grumble moan whinge.

"The six solenoid valves are relatively large because of the response time required by the system."
Duh?? Bob Moog does fast valves - the requirement here is glacial.

If these solenoid valves were operated for long periods of time under conditions of
high temperature or high currents, they would overheat and fail."

Well spec then correctly then.

To prevent this, the valve driver controls the amount of current that flows through each solenoid coil. Because the
current required to open the solenoid is considerably higher than the current required to hold
the solenoid open, a hit and drop signal is used."

Well if you must, you must, but don't blame me when it goes wrong, which it will.

"Upon a valve open request the control voltage is near 0V for 0.050 seconds (50 milliseconds) then is pulsed to limit current through
the coil. The pulsed voltage will read approximately 9 volts with a high impedance DVOM or can be viewed with an oscilloscope to be a 24 KHz 12-volt square waveform."

Talk about making it hard for yourself....

"The steady state current passing through each coil is approximately 1 amp."
How big are the armatures they are moving???

Think i have posted that PDF on here before. Remember the lift and soft drop discussions.

youngshag · Feb 25, 2015

Quite right Wammers. Everything seemed tight but I might have improved a connection or two. Either way all is good. Cheers.

youngshag · Feb 25, 2015

Castor, thems some sexy words you usin'!! Most went over my head.....No, it all went over my head.

Castor · Feb 25, 2015

youngshag said:
Castor, thems some sexy words you usin'!! Most went over my head.....No, it all went over my head.

Sorry - it's my thing - I do industrial automation & special purpose machinery for a living and have done for over forty years. The automotive industry drive me ***insane*** because rather than use lessons learnt from other industries, they insist on reinventing the wheel. Everything automotive is non-standard.

So every pressure sensor, every temperature sensor, motion sensor - rather than being £3.99 from Maplin is £103.99 from your main stealer.
And usually technologically retrograde from standard practice.
And a pig to fix, usually.

Whinge moan etc.

Castor · Feb 25, 2015

wammers said:
Think i have posted that PDF on here before. Remember the lift and soft drop discussions.

I wish I'd never seen it.
My obsessive brain now has to fix it - at least in principle.

:ballchain::ballchain:"Resistance is futile".

wammers · Feb 25, 2015

Castor said:
Sorry - it's my thing - I do industrial automation & special purpose machinery for a living and have done for over forty years. The automotive industry drive me ***insane*** because rather than use lessons learnt from other industries, they insist on reinventing the wheel. Everything automotive is non-standard.

So every pressure sensor, every temperature sensor, motion sensor - rather than being £3.99 from Maplin is £103.99 from your main stealer.
And usually technologically retrograde from standard practice.
And a pig to fix, usually.

Whinge moan etc.

Yep true, one would wonder why a few plastic moldings and electronics possibly costing less than a tenner to produce, when assembled into a EAS selector switch cost over £300.00.

Datatek · Feb 25, 2015

Castor said:
Muchacho interested in all this. I too get random calls to wade, which could well be the driver pack and/or its connectors - but today I saw detail that showed the ludicrous kludge that the driver pack applies to the solenoids to keep the current down.
Whoever signed that off wants hanging...

With that degree of designed-in complexity, what chance do we have?

Pick & hold is an industry standard standard practice, I have been designing and manufacturing controllers for air powered systems since 1986.
Pick & hold is not inherently unreliable. The solenoid armatures operate against considerable spring tension, therefore a pretty hefty current pulse is required to get them moving. The pulsed hold current looks to be a nonsense on the face of it, but may be more effective in holding than a lower flat line voltage when the unit is exposed to shock loads on rugged terrain.
It's not difficult to design a simpler replacement for the driver pack, the difficulty would come in being absolutely sure it performed to spec in all conceivable conditions.
I have repaired 2 driver packs, both of which seem to be functioning correctly.

Castor · Feb 25, 2015

For what it's worth (not much in the real world unless someoene wants to pay for the develpment time) a retrofit solution might be:-

One of these:-
Valve terminal VTUG | Festo Great Britain
Controlled by a one of these (replacing all the functionality of the EAS/BEMS/etc.):-
Process and Automation Centre, RS is a world leading distributor of Process Control and Automation Components; with the widest range of products from control gear to sensors and PLCs to pneumatics from the market leading brands.
HMI from here:-
http://w3.siemens.com/mcms/topics/en/simatic/display-technology/Pages/default.aspx
this would also be the diagnostic screen, of course.

Engine management:-
MegaSquirt-II - Advanced Electronic Fuel Injection Computer by Bowling & Grippo ©2005

Ironically, the trickiest thing to implement would be the statutory OBD2, which is, in common with all things automotive, non industry standard.

All of the above, repackaged and supplied in quantity for production, shouldn't cost more than a grand or so I reckon.
Maybe I'll get some clones made in China.....

wammers · Feb 25, 2015

What the hell happened to the quoted posts on this thread?

blue beasty · Feb 25, 2015

wammers said:
What the hell happened to the quoted posts on this thread?

They look alright to me

Have ya put the wrong glasses on again?

Castor · Feb 25, 2015

Datatek said:
but may be more effective in holding than a lower flat line voltage when the unit is exposed to shock loads on rugged terrain

Recognised - but it's going to be one hell of a shock.
I've got some ordinary valves here that we have been knocking about quite severely - seeing several G at least, and they are operating and holding in securely at [email protected].

Datatek said:
It's not difficult to design a simpler replacement for the driver pack, the difficulty would come in being absolutely sure it performed to spec in all conceivable conditions.

Agreed - I don't believe they really did any of this in the first instance....

Datatek said:
I have repaired 2 driver packs, both of which seem to be functioning correctly.

That must be very rewarding - I know I get a warm glow when I know it's sorted. I recently did the ABS valve array for my Volvo V70 which involves de-encapsulating, re-capacitor-ing, re-solder-flowing and all that stuff. Took ages. Like surgery.
That's *another* ****ing stupidly designed arrangement too.... but it feels good when it works.

Datatek · Feb 25, 2015

Castor said:
Recognised - but it's going to be one hell of a shock.
I've got some ordinary valves here that we have been knocking about quite severely - seeing several G at least, and they are operating and holding in securely at [email protected].

17.2 volts would fry the EAS solenoids in no time, they pull at 12 volts and will hold at around 5 or 6 volts from memory.

youngshag · Feb 25, 2015

Well I reckon between the lot of you, you could come up with a reliable, cheap alternative and make a bomb floggin' it. Show me the money!!

Castor · Feb 25, 2015

>>>>reliable, cheap alternative and make a bomb floggin' it

No. People would expect Service!

Datatek · Feb 26, 2015

youngshag said:
Well I reckon between the lot of you, you could come up with a reliable, cheap alternative and make a bomb floggin' it. Show me the money!!

The problem with selling a replacement driver pack is the testing required in all conditions to ensure reliability, conformity etc. Selling something that affects the suspension without the correct approvals may well invalidate insurance on the vehicle.
The easy option for me is to make a copy of the original, yes it's over complicated and old technology, but no approvals would be needed.
I believe I have found the source of many of the failures and it's a simple fix. When testing is complete I will publish the fix.

Castor · Feb 26, 2015

Datatek said:
I believe I have found the source of many of the failures and it's a simple fix. When testing is complete I will publish the fix.

....and that, for the vast majority, is the correct way to go. I look forward to this with immense interest - and I will probably apply the fix if applicable.

It's only control freaks like me want to change everything.

youngshag · Feb 26, 2015

Without control freaks and people wanting to make a difference we'd all be at the main dealer getting dry bummed. That's why this forum is priceless.

EAS spurious inputs

wammers

No longer with us, RIP

youngshag

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youngshag

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Castor

Trainee maniac

Castor

Trainee maniac

wammers

No longer with us, RIP

Datatek

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Castor

Trainee maniac

wammers

No longer with us, RIP

blue beasty

Leaks an prone to bits dropping off

Castor

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Datatek

Well-Known Member

youngshag

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Castor

Trainee maniac

Datatek

Well-Known Member

Castor

Trainee maniac

youngshag

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