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Old 18th August 2009, 11:37   #61
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Originally Posted by anupmathur View Post
Satish, the whole blade assembly would, in effect, mean the whole rotor.
Could you please point me to an article/brochure?
I have never come across or read about the entire rotor being axially moved inside the turbo casing to control volume.

It would have to be a nozzle ring or sleeve of some sort. Or waste gates to let the exhaust bypass the turbo.
Anup,
This article refers to the Cummins VGT. It has a sliding nozzle ring and the vanes (rotor) slides axially.
www.cummins.com/turbos - VGT

Satish
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Old 18th August 2009, 12:23   #62
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Originally Posted by VeeTee View Post
Anup,
This article refers to the Cummins VGT. It has a sliding nozzle ring and the vanes (rotor) slides axially. www.cummins.com/turbos - VGT
Satish
Hi VeeTee,
Its the stator (ring of fixed vanes) that's moved axially right ? The rotor of the turbine operates the same as in all turbos.
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Old 18th August 2009, 14:30   #63
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Correct. The actuator connector is mounted on a sleeve coaxial to the main shaft, and moves the profile ring (kind of like stator vanes) which gradually constrict the holes (nozzles) through which the exhaust gases enter into the impeller. The shaft connecting the impeller to the compressor disc does not move axially.

But is this pneumatically controlled VGT used in cars? I have seen this only in Mack and Peterbilt trucks / rigs.
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Old 18th August 2009, 17:59   #64
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Originally Posted by im_srini View Post
Hi VeeTee,
Its the stator (ring of fixed vanes) that's moved axially right ? The rotor of the turbine operates the same as in all turbos.
I am not sure if it was on the stator. I don't remember that. This was electrically controlled (not pneumatic). I don't know if this is used in passenger cars. It was on bigger engines.
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Old 31st August 2009, 17:34   #65
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My 2 cents

Source: BTN Turbo

The site has a nice demo video of a VNT

A Garrett® VNT® turbocharger works by adjusting the gas throat section at the inlet of the turbine wheel in order to optimize turbine power with the required flow velocity.
At low engine speed and small gas flow, the turbocharger reduces the throat section, increasing turbine power and boost pressure. At full engine speed and high gas flow, the VNT™ turbocharger increases the throat section, avoiding turbocharger overspeed and maintaining the booster pressure required by the engine. The throat section modulation can be controlled directly by the compressor pressure through the use of a pressure actuator, or by the engine management system using a vacuum actuator. To modify the throat section, VNT™ Multivane™ models use a mobile multivane system composed of a number of vanes which rotate relative to the turbine wheel axis.
The benefits of VNT™ technology are:
  • Higher power
  • Higher torque
  • Improved transient response
  • Lower fuel consumption
  • Lower emissions
  • Improved braking power
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Old 3rd September 2009, 08:03   #66
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@ VeeTee: This is a holset concept & was in production here. proved very unreliable. Detroit diesel also attempted to put it into production.
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Old 3rd September 2009, 21:01   #67
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Default EGR and Cooled ECR

"In the past, a fair number of car owners disconnected their EGR systems in an attempt for better performance and some still do. The belief is either EGR reduces power output, causes a build-up in the intake manifold, or believe that the environmental impact of EGR outweighs the NOx emission reductions. Disconnecting an EGR system is usually as simple as unplugging an electrically operated valve or inserting a ball bearing into the vacuum line in a vacuum-operated EGR valve. In most modern engines, disabling the EGR system will cause the computer to display a check engine light. In almost all cases, a disabled EGR system will cause the car to fail an emissions test, and may cause the EGR passages in the cylinder head and intake manifold to become blocked with carbon deposits, necessitating extensive engine disassembly for cleaning."
Exhaust gas recirculation - Wikipedia, the free encyclopedia

The below link says AVL has it ready.
AVL - Cooled EGR and Particulate Trap
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Old 3rd September 2009, 21:49   #68
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Quote:
Originally Posted by jkdas View Post
"In the past, a fair number of car owners disconnected their EGR systems in an attempt for better performance and some still do. The belief is either EGR reduces power output, causes a build-up in the intake manifold, or believe that the environmental impact of EGR outweighs the NOx emission reductions.
I can only think of how hard the engineers have worked in order to get the EGR working inorder to control the emissions. I would definitely ask any one to never disconnect the EGR systems. 20% EGR could significantly bring down the NOx emissions from 18-19 g/kWh to 2-3g/kWh.
AVL is one hell of a company Hats off to them !!
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