The document explains the function and benefits of turbochargers, which are devices that enhance the efficiency and power output of internal combustion engines by utilizing waste exhaust energy. It compares fixed geometry turbochargers (FGT) and variable geometry turbochargers (VGT), highlighting the advantages of VGTs in improving performance and reducing turbo lag. Additionally, it describes different actuation systems for turbochargers and mentions applications in various engine types, including off-highway engines.

1. Presented by :
A.V.ANKIT
CB.EN.P2ATE16004
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2.  What ? - It is a turbine-driven forced induction device which utilizes the waste
energy from the exhaust gases.
 Why ? - It increases the internal combustion engine's efficiency and power output
by forcing extra air into the combustion chamber.
 Where ? - It is mainly used in CI engines and now also in SI engines.
 How ? - It is placed just after the exhaust manifold, all the exhaust gases pass
through the turbine converting heat energy to rotational energy and then to the
further after treatment devices.
The main difference between turbos’ used in passenger
vehicles and off-highway vehicles is just the ‘SIZE’ of
turbine and compressor.
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3. Turbine
compressor
Common shaft
Exhaust gas inlet to turbine
Ambient air inlet
Exhaust gas outlet
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4.  The high density exhaust gases flow through the turbine and applies pressure to
rotate it, after energy loss to the turbine the exhaust gas exits to the vehicle
exhaust after treatment system.
 The rotation of turbine helps spinning of the compressor wheel which is connected
with the help of a common shaft.
 This compressor pushes extra air (and oxygen) into the cylinders, allowing them
to burn more amount of fuel so as to compensate for increasing demand of power
and torque.
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5. WORKING OF TURBOCHARGER
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6.  Aim of the forced induction devices is to maintain a correct aspect ratio (AR)
which is an important parameter in addition to rotor size, that controls turbo lag
and over boosting.
 This is the ratio of cross sectional area of the volute divided by the distance from
the centre of this cross sectional area to the geometric centre of the volute. A small
AR means that the velocity of the exhaust gas is increased and, therefore, a
greater kinetic energy is available to the turbine rotor.
 Variable geometry devices in essence manipulate the AR value by altering the
cross sectional area of the volute in order to increase air velocity at low engine
speeds.
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7. 1. FIXED GEOMETRY TURBOCHARGERS (FGT) –
 This is the simplest design that is possible from a control perspective. The turbine
and compressor geometry are fixed that uses no means to control boost pressure.
 These turbochargers are optimized for a particular operating condition.
 Although in FGT’s there are means to control boost pressure, there are two
methods through which we can control its boost.
 Exhaust side bypass(Waste-gate) -Wastegated turbo allows a portion of the exhaust gas
to bypass the turbine wheel thus “wasting” a portion of the exhaust energy.
 Inlet side bypass to bypass flow from the compressor inlet.
 The most widely recognised problem with fixed geometry devices is turbocharger
lag and the poor transient response of the turbocharger at low engine loads.
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9. 2. VARIABLE GEOMETRY TURBOCHARGERS(VGT) –
 These are the most commonly used turbochargers in modern engines.
 VGT devices are designed to increase boost pressure at low speeds, reduce
response times, increase available torque, decrease the boost at high engine
speeds to prevent over-boosting, reduce engine emissions, improve fuel economy
and increase the overall turbocharger operating range.
• Variable geometry
devices in essence
manipulate the AR value
by altering the cross
sectional area of the
volute in order to
increase air velocity at
low engine speeds.
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11.  Figure shows the effect of a VGT in comparison to a fixed geometry device during
acceleration in second gear of a 6-cylinder, 11 L turbodiesel engine.
• The solid lines on the graphs indicate a
steeper curve in all three cases.
• VGT offers improved turbocharger
rotational speed, engine speed and boost
pressure than a regular turbocharger.
• It can also be seen at around 3 s that the
nozzle is opened to reduce boost pressure
and therefore prevent over-boosting.
• A waste gate is not needed and therefore
there is no associated throttling loss.
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13. Pivoting vane turbocharger in fully closed (upper) and fully open (lower) positions.
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14.  Pneumatic actuation system –
 It uses air to move a piston inside a
closed cylinder.
 It works on the principle of pressure
difference.
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15.  Hydraulic actuation system –
 The hydraulic type of actuation device can be fed with the engine oil as means of providing
movement to the nozzle ring or variable vanes.
 This works using the same principle as the pneumatic variant, but introducing a fluid (instead of
a gas) onto a piston which then acts upon the nozzle ring or pivoting vane through a yolk or vane
ring.
 Unlike the pneumatic variant, the fluid in hydraulic systems is not compressible, which means
there is more control over the actuation.
 In this mechanism a PWM vane position control solenoid valve uses engine oil pressure and the
ECU signal to move the turbochargers unison ring.
 A hydraulic piston will move a geared rack mechanism, which in turn, rotates a cam-shaped
pinion gear thereby articulating the vanes.
 The vanes are fully opened when no oil flow is commanded to move the servo piston and to
reduce opening as oil pressure increases through the vane position control solenoid valve.
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17.  Electric actuation system –
 Electronic systems make the most accurate actuators. This is because voltage can provide very
fine control, which, through a small selector gear, powers the VGT.
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18. Some of the JOHN DEERE engines employing FGT’s
PowerTech M 4.5L 55 kW (74 hp) PowerTech E 2.4L 45 – 49 kW (60 – 66 hp)
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19. PowerTech PWX 4.5L 56 – 91 kW (75 – 122 hp)
PowerTech PVX 4.5L 93 – 129 kW (125 – 173 hp)
PowerTech PVX 6.8L 104 – 129 kW (140 – 173 hp)
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20. PowerTech PSX 6.8L 168 – 224 kW (225 – 300 hp)
PowerTech PSX 9.0L 242 – 317 kW (325 – 425 hp)
PowerTech PSX 13.5L 298 – 448 kW (400 – 600 hp)
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• Series turbocharging is usually preferred
in off highway engines.
• Parallel turbocharging is used in some of
SUVs’ and sports cars.

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• In two-stage series turbocharging, fresh
air is drawn into the first stage
compressor, where its pressure is raised
about 2 to 2.5 times atmospheric
pressure.
• This pressurized air is then drawn into
the second stage compressor, where the
pressure is raised another 2 to 2.5
times.
• The air is then cooled and the resulting
charge air at the engine’s intake
manifold is typically 4 to 5 times that of
atmospheric pressure – and about 20°C
higher than ambient temperature. By
splitting the compression of the charge
air between two turbos, both
compressors operate at peak efficiency.
• Also, the lower pressure ratios for each
stage mean lower rotating speeds,
which results in improved reliability for
the bearing systems, compressor wheels

23.  Review paper :- “Variable Geometry Turbocharger Technologies for Exhaust Energy
Recovery and Boosting‐A Review” by-
 Adam J. Feneleya, Apostolos Pesiridisa,⁎, Amin Mahmoudzadeh Andwaria,b.
 Diesel Engine Technology Understanding & Servicing Contemporary Clean Diesel
Technology - Gus Wright.
 Turbocharger – Wikipedia.
 Off-Highway Diesel Engines Interim Tier 4/Stage III B catalogue
 From JOHN DEERE - www.JohnDeere.com/tier4
 https://turbo.honeywell.com/our-technologies/twostage-serial-turbochargers/
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