A8 Parts Forum  

Go Back   A8 Parts Forum > A8 D3 > D3 - Engine Bay

D3 - Engine Bay Everything under the bonnet

Reply
 
Thread Tools Display Modes
  #11  
Old 6th March 2020, 08:20 AM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

The electrical connection is for a solenoid which controls a valve to an air pocket inside the mount. The ECU controls the effective strength of the mount by switching on / off what is basically an air spring. There's an SSP on them somewhere - I'll see if I can find it.

The D4 actually has a separate computer just to control the active engine mounts
Reply With Quote
  #12  
Old 10th March 2020, 04:42 PM
Architex_mA8tey's Avatar
Architex_mA8tey Architex_mA8tey is offline
Moderator
 
Join Date: Jan 2009
Location: London/Oxford/Swindon
Posts: 7,648
Default

Here's Audis take on the D4 4.0T Tfsi Active Engine Mounts :

Active engine mounts: counteracting vibration for greater refinement
Audi normally uses firm, sporty settings for its engine mounts. For many years now certain models – notably the A8 at the top end of the range – and various engines have had switchable electromagnetic mounts. These have two operating settings: at idle speed they have a “soft” characteristic to prevent noise and vibration from reaching the interior, but when the car is being driven a firmer damping rate is selected in order to suppress engine vibration.

The active engine mounting that Audi has developed for the 4.0 TFSI takes this technology a decisive step further – it cancels out engine vibrations with out-of-phase counter-oscillations. The key component is an electromagnetic oscillating-coil actuator. This has a rapid stroke that is transmitted via a flexible diaphragm to the hydraulic fluid in the mounting, which also absorbs oscillating movements from the engine. In the fluid these are overlaid by the actuator movements and cancelled out.

The control units for the active engine mounts receive their signals from two sources. Engine speed is detected by the crankshaft sensor; these signals are used to compute the precise phase and frequency of the actuator signal. Acceleration sensors on the two engine mounts supply the data that determine the amplitude necessary to cancel out the vibration.

When the new 4.0 TFSI is running in the four-cylinder mode, it generates a certain amount of engine vibration and drumming noise of what is known as the second order. They are not typical of a V8, but the counter-vibration generated by the active mounts reduces them to an undetectable level.

At idle speed with all eight cylinders in operation, engine excitation of the fourth order occurs. This too is largely eliminated by the active engine mounts so that the engine appears to be running even more smoothly.
__________________

Confidence is the feeling you have before you know better . . . .
Audi A8 D2 3.7 Quattro Sport 1999 FL - Melange
2nd Place Winner - A8-Freunde Annual German Meet 2012 at Edersee
20" x 9" Bentley GTC Wheels with 385mm W12 Front Discs & Bentley Caliper Covers, Front Lowered on Coilovers, Xenons, Combined DRLs and LED Foglights to modified OEM front fog lamp position, Alcantara/Leather, Full Black Alcantara headlining + pillars and blind shelf, Bespoke Flat Bottomed Sports Steering Wheel, Dark Myrtle Wood, Autodim Mirrors, Bose, Blinds, Digital TV, Ski Hatch, Modified rear exhaust section for extra V8 Burble
Audi S8 D2 Final Edition 2002, Avus Silver with Red Leather Interior
Tiptronic with Sport mode button, Sony rear entertainment package, Bose sound system, Audi Navigation Plus, 20 inch Final Edition alloys, Full Cat Back Stainless Milltek exhaust, giving a great V8 burble
Audi A8L D2 4.2 Petrol with LPG - Ebony Black
Audi A8L D4 FL 4.0T Petrol twin turbo - Havana Black
Audi A2 1.6 FSi Sport - Dolphin Grey with Votex body kit and Red Leather Interior
and some other A8's A8L's and Mercs
Reply With Quote
  #13  
Old 26th March 2020, 02:00 AM
Versace Versace is offline
Member
 
Join Date: Sep 2018
Posts: 52
Default

Quote:
Originally Posted by MikkiJayne View Post
The electrical connection is for a solenoid which controls a valve to an air pocket inside the mount. The ECU controls the effective strength of the mount by switching on / off what is basically an air spring. There's an SSP on them somewhere - I'll see if I can find it.

The D4 actually has a separate computer just to control the active engine mounts

How exacty does this work??
__________________
S8 D3 FL II.
Porsche Cayenne 958 Turbo
BMW E83 X3 3.0d M-Sport
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 10:58 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.