piezoelectric injectors in the CDI? - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 03-10-2009, 01:59 PM
BenzWorld Member
 
Date registered: Feb 2009
Vehicle: W211E320CDI
Location: USA
Posts: 159
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
(Thread Starter)
piezoelectric injectors in the CDI?

Question: does the E320 CDI use piezoelectric injectors? I think I read that it does.

If so, how do they work?

Is it that they receive an electrical charge and the shape of the injector changes enough to allow an opening for the fuel to flow? Trying to get an understanding of the mechanics of the thing.

What are the drawbacks of such a system?

Thanks!
Silly_me is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 03-10-2009, 02:13 PM
BenzWorld Member
 
Date registered: Feb 2009
Vehicle: W211E320CDI
Location: USA
Posts: 159
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
(Thread Starter)
Found this information:

Quote:
Originally Posted by Automotive Business Review
Mercedes C250 CDI to premiere Delphi's Direct Acting Piezo injector

US-based automotive parts manufacturer Delphi has announced that, following the development in cooperation with Daimler engineering teams, the new Mercedes C250 CDI will premiere Delphi's Direct Acting Piezo injector.

According to Delphi, its new Direct Acting Common Rail (CR) represents a radical break-through in diesel injection technology as the injector needle is directly activated by the piezo stack, removing the hydraulic circuit and its associated lag and energy consumption. This change enables vehicle manufacturers to comply with future emission legislations while providing more power and fuel economy.

Delphi's Direct Acting CR system uses a patented direct-acting concept in which the injector needle is set in motion directly by a piezo ceramic actuator instead of being moved via an electro-hydraulic circuit as with existing fuel injection technologies.

The piezo ceramic actuator directly operates the needle valve of the injector for initial lifts, such as those obtained in pilot injections, and a motion amplifier is used to help complete the lift for large injections. This enables the injector to spray fuel into the combustion chamber faster, with much improved spray momentum and accuracy, at higher pressures.

Jose Avila, general manager of Delphi Diesel Systems, said: "Today, Delphi surpassed a major milestone in diesel technology history and there is no better way to write this new chapter than to be partnered with Mercedes-Benz, the company with the industry's longest history in diesel engines."
Very neat, can anyone confirm if this is used in the I6 CDI engine?
Silly_me is offline  
#3 (permalink) Old 03-10-2009, 07:25 PM
BenzWorld Elite
 
Kajtek1's Avatar
 
Date registered: Dec 2005
Vehicle: W210 E300DT x2/w211wagon4M / Ford SD. Seeking diesel pushmower
Location: CA Bay Area
Posts: 27,284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 79 Post(s)
I was replacing injector seals on cdi and the first note on the repair manual was "DON"T TAKE THE INJECTOR APART".
At $580 retail (a piece) they have to be fancy, but if you want to mess with them you buy your own
Kajtek1 is online now  
#4 (permalink) Old 03-10-2009, 08:57 PM
BenzWorld Elite
 
Date registered: May 2005
Vehicle: '07 GL320CDI
Location: Albuquerque
Posts: 5,070
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Silly_me View Post
Very neat, can anyone confirm if this is used in the I6 CDI engine?
I think it's new for the V6 (OM642) diesel only. (And some recent 4-cyl diesels not in North America such as the 250 in the example ... which is not Mercedes' first use of piezo electrics but it's probably first use of follower Delphi's stuff.)

Remember, the I6 CDI (OM648) really dates back to 1998.

Piezo appears to have started here: http://www.bosch-presse.de/TBWebDB/e...arch=1&id=2508

Kent Christensen
Albuquerque
'07 GL320CDI

Last edited by lkchris; 03-10-2009 at 09:03 PM.
lkchris is offline  
#5 (permalink) Old 03-11-2009, 11:53 AM
BenzWorld Elite
 
drivbiwire's Avatar
 
Date registered: Mar 2006
Vehicle: 2006 E320 CDI, 2009 ML320 Bluetec, 2009 GL320 Bluetec
Location: Boise ID
Posts: 1,476
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
drivbiwire is offline  
#6 (permalink) Old 03-11-2009, 01:27 PM
BenzWorld Member
 
Date registered: Feb 2009
Vehicle: W211E320CDI
Location: USA
Posts: 159
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
(Thread Starter)
That is really cool, so it is a stack of piezo disks that actuate the plunger when charged. I'd imagine this would be a more reliable part than the hydraulically actuated ones.
Silly_me is offline  
#7 (permalink) Old 03-11-2009, 02:33 PM
BenzWorld Elite
 
drivbiwire's Avatar
 
Date registered: Mar 2006
Vehicle: 2006 E320 CDI, 2009 ML320 Bluetec, 2009 GL320 Bluetec
Location: Boise ID
Posts: 1,476
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Much more reliable! The cycle rate is 10 injections per combustion stroke, although MB is not using the injectoion system anywhere near its full capability.

The injection events are broken up to "shape" the combustion pressure rise in the cylinder. To do this, they inject multiple times as the piston approaches TDC as well as vary the amount of fuel inejected during each injection sequence. This lower emissions by injecting fuel at specific points in the combustions process that promote the most efficient/lowerst emissions burn. Older diesels simply dumped in one big slug of fuel and when it ignited resulted in a rapid pressure rise and resulting knock. The large single injection event also caused some fuel to go unburned increasing emissions greatly.

Aside from that, the Piezo injectors are much simpler and reduce the complexity greatly. Another side benefit is along with the software that drives the fuel system they are able to provide much tighter control of the fuel injection process again translating into higher efficiency and lower emissions AND increasing the component life of the fuel system.

DB

Last edited by drivbiwire; 03-11-2009 at 02:37 PM.
drivbiwire is offline  
#8 (permalink) Old 03-12-2009, 10:00 PM
BenzWorld Member
 
Date registered: Feb 2007
Vehicle: '06 E320CDI
Location: Southern US
Posts: 101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by drivbiwire View Post
AND increasing the component life of the fuel system.

DB
So how long are they supposed to last? At $580 a pop, it'd better be a long time...
benz_driver is offline  
#9 (permalink) Old 03-13-2009, 02:51 PM
BenzWorld Elite
 
drivbiwire's Avatar
 
Date registered: Mar 2006
Vehicle: 2006 E320 CDI, 2009 ML320 Bluetec, 2009 GL320 Bluetec
Location: Boise ID
Posts: 1,476
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
How clean is your fuel?

The wear items are the nozzles, these can be replaced at far less than the cost of a whole injector. However MB in the US will not permit any of the dealerships to perform this function since they do not have the training or equipment.

The best advice, replace the fuel filter as specified every 26K using the best quality filters you can get (OEM, or MANN-Hummel).

Use good quality fuel that is rated at 400HFFR or lower for lubricity. Most US fuels don't meet this spec, so small amount of fuel additives may be needed to comply with this spec. In most cases 2%-5% Biodiesel will improve the lubricity of the worst fuels (520HFFR) and reduce it to the mid 300 range.

At 24,500psi any amount of dirt will act like a hydraulic cutting jet, it will slice thru any metal or in the case of a fuel system, erode the .117 micron nozzles holes (7 in total on each injector). Also high amount of dirt larger than 2 microns will oval the holes and destroy the spray pattern and ruin the characteristics of the fuel patterns...

Fuel filtering and fuel quality is the holy grail of injection system component life.

DB
drivbiwire is offline  
#10 (permalink) Old 03-13-2009, 11:11 PM
BenzWorld Elite
 
Kajtek1's Avatar
 
Date registered: Dec 2005
Vehicle: W210 E300DT x2/w211wagon4M / Ford SD. Seeking diesel pushmower
Location: CA Bay Area
Posts: 27,284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 79 Post(s)
The $580 injectors are not piezzo-electronics.
But German engineers had a brain fart putting cheap 70 cents seal under them.
I can only hope they improve seal with piezzo technology.
Kajtek1 is online now  
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W211 E-Class


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Topic Author Forum Replies Last Post
vito 108 cdi injectors tev V-Class 6 04-18-2009 02:04 AM
Injectors Leaking Compression -2001 Sprinter 313 CDI xmusic General Mercedes-Benz 0 02-11-2009 01:02 PM
V220 CDI, Bodge of the century for leaking injectors. leesupermoto V-Class 3 08-26-2008 10:56 PM
E 270 CDI and E 200 CDI from my uncle's korisnikone W211 E-Class 4 12-10-2005 07:57 AM
Are the V8 diesel 420 cdi, 320 cdi ( europa 4) the future Zé Bocaina G-Class 4 05-26-2005 06:41 AM

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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome