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9. DUAL MASS FLYWHEEL (DMF) & DRIVE PLATE
1) Overview
Flywheel is installed on crankshaft. When
starting the engine, this functions as follows:
Reducing the irregular speed of crankshaft
due to unbalanced combustion -> Improving
the power train NVH, Improving the driving
performance
Reducing the clutch noise by using ball
bearing
Improving the durability of DMF by using
strong arch spring -
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2) Layout
Spring guide
Drive plate
Primary cover
Primary flywheel
Internal/external ringSecondary flywheel
Ring gear
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Torque change curve of engine and drive shaft
Compression stroke Combustion stroke
Small changes from engine (k):
Damper increases the torque changes to clutchLarge changes from engine (j):
Damper decreases the torque changes to
transaxle by absorbing the impact
3) Operation
Compensating the irregular operation of engine: The secondary flywheel operates almost evenly
so does not cause gear noises
The mass of the primary flywheel is less than conventional flywheel so the engine irregularity
increases more (less pulsation absorbing effect).
Transaxle protection function: Reduces the torsional vibration to powertrain (transaxle) by reducing
the irregularity of engine. -
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4) Features
Reduced vibration noise from the powertrain by blocking the torsional vibrations
Enhanced vehicle silence and riding comforts: reduced engine torque fluctuation
Reduced shifting shocks
Smooth acceleration and deceleration -
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5) Advantages
Improved torque response by using 3-stage type spring: Strengthens the torque response in all
ranges (low, medium, and high speed) by applying respective spring constant at each range.
Stable revolution of the primary and secondary wheel by using planetary gear: Works as auxiliary
damper against spring changes
Less heat generation due to no direct friction against spring surface: Plastic material is covered on
the spring outer surface
Increased durability by using plastic bushing (extends the lifetime of grease) -
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6) Drive Plate
Drive plate receives the power from the start motor when starting the engine. With this, the drive plate
initially drives the power train system. And, it is connected to the torque converter to transfer the engine
torque to the power train system.
Trigger ring
Drive plate
Components ▶
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2) Inspection of Turbocharger
When problem occurs with the turbocharger, it could cause engine power decline, excessive discharge
of exhaust gas, outbreak of abnormal noise and excessive consumption of oil.
On-board Inspection 1.
Check the bolts and nuts foe looseness or missing
Check the intake and exhaust manifold for looseness or damage
Check the oil supply pipe and drain pipe for damages
Check the housing for crack and deterioration -
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Inspection of turbine 2.
Remove the exhaust pipe at the opening of the turbine and check, with a lamp, the existence of
interference of housing and wheel, oil leakage and contamination (at blade edge) of foreign materials.
Interference: In case where the oil leak sign exists, even the small traces of interferences on the
turbine wheel mean, most of times, that abrasion has occurred on the journal bearing. Must
inspect after overhauling the turbocharger.
Oil Leakage: Followings are the reasons for oil leakage condition -
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Problems in engine: In case where the oil is smeared on inner wall section of the exhaust gas
opening.
Problems in turbocharger: In case where the oil is smeared on only at the exhaust gas
outlet section. *
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Idling for long period of time can cause oil leakage to the turbine side due to low pressure of exhaust
gas and the rotation speed of turbine wheel. Please note this is not a turbocharger problem.
Oil Drain Pipe Defect
In case where oil flow from the turbocharger sensor housing to the crank case is not smooth
would become the reason for leakage as oil builds up within the center housing. Also, oil thickens
(sludge) at high temperature and becomes the indirect reason of wheel hub section. In such case,
clogging and damage of the oil drain pipe and the pressure of blow-by gas within the crank case
must be inspected.
Damages due to Foreign Materials.
When the foreign materials get into the system, it could induce inner damage as rotating balance
of the turbocharger gets out of alignment. -
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3) Inspection of Turbine
Thoroughly check the followings.
Must absolutely not operate the turbocharger with the compressor outlet and inlet opened as it
could damage the turbocharger or be hazardous during inspection.
Interference: In case where is trace of interference or smallest damage on the compressor wheel
means, most of times, that abrasion has occurred on the journal bearing. Must inspect after the
overhaul.
Oil Leakage: The reason for oil leakage at the compressor section is the air cleaner, clogged by
substances such as dust, causes the compressor inlet negative pressure. -
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Rotating in high speed at no-load for extended period of time can cause oil leakage to the
compressor section as oil pressure within the center housing gets higher than pressure within
the compressor housing.
Overuse of engine break (especially in low gear) in down hill makes significantly low exhaust gas
energy compared to the time where great amount of air is required during idling conditions of the
engine. Therefore, amount of air in the compressor inlet increases but the turbocharge pressure
is not high, which makes negative a.
b.
No problem will occur with the turbocharger if above conditions are found in early stage but oil
leaked over long period of time will solidify at each section causing to breakout secondary defects.
Damages by foreign materials: In case where the compressor wheel is damaged by foreign materials
requires having an overhaul. At this time, it's necessary to check whether the foreign materials have
contaminated intake/exhaust manifold or inside of engine.
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3. TROUBLESHOOTING
The followings are cautions to take in handling defects of turbocharger, which must be fully aware of.
1) Cautions
After stopping the engine, check whether the bolts on pipe connecting section are loose as well as
the connecting condition of vacuum port and modulator, which is connected to the actuator.
During idling of the engine, check for leakage in the connecting section of pipe (hoses and pipes,
duct connections, after the turbocharger) by applying soap water. The leakage condition in the
engine block and turbine housing opening can be determined by the occurrence of abnormal noise
of exhaust.
By running the engine at idle speed, abnormal vibration and noise can be checked. Immediately
stop the engine when abnormal vibration and noise is detected and make thorough inspection
whether the turbocharger shaft wheel has any damages as well as checking the condition of
connections between pipes.
In case where the noise of engine is louder than usual, there is possibility of dampness in the areas
related with air cleaner and engine or engine block and turbocharger. And it could affect the smooth
supply of engine oil and discharge.
Check for damp condition in exhaust gas when there is sign of thermal discoloration or discharge of
carbon in connecting area of the duct.
When the engine rotates or in case where there is change in noise level, check for clogging of air
cleaner or air cleaner duct or if there is any significant amount of dust in the compressor housing.
During the inspection of center housing, inspect inside of the housing by removing the oil drain pipe
to check for sludge generation and its attachment condition at shaft area or turbine side.
Inspect or replace the air cleaner when the compressor wheel is damaged by inflow of foreign
materials.
Inspect both side of the turbocharger wheel after removing inlet and outlet pipe of the turbocharger. 1.
2.
3.
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5.
6.
7.
8.
9.
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Control
rangeTurbocharger
driving
mechanismControl
methodEffectImproved
performance
At low
speedNarrows the
flow passage fo
r
the exhaust gas
by folding the
vanesThe flow rate is
increased as the
exhaust gas passes
the narrow passage
→ Increased
turbine & impeller
speed, Increased
compressive forceImproved
low speed torque
4. OPERATING PRINCIPLES
The E-VGT is designed to get more improved engine power in all ranges by controlling the turbine as
follows:
1) How it Works at Low Speed
Normal turbocharger cannot get the turbo effect because the amount of exhaust gas is not enough
and the flow speed is slow in a low speed zone, but VGT allows the flow passage of exhaust to narrow,
resulting in increasing the flow speed of exhaust gas and running the turbine quickly and powerfully.
Therefore, as VGT can intake more air than normal turbocharger, it can give the benefit of the
increased output even in a low speed zone.
Turbocharger lag
The turbocharger is at idle speed when there is no load or it is in the normal driving condition. During
this period, the amount of exhaust gas passing through the turbine is not enough to turn the
compressor wheel (impeller) fast. Therefore, the intake air is not compressed as needed. Because
of this, it takes time for turbocharger to supply the additional power after the accelerator pedal is
depressed. This is called "turbocharger lag".Basic principle at low speed
At low speed, it utilizes the principle of venturi.
For example, when air flows through the venturi
tube, the flow speed is faster and the pressure
is lower at the point "A". In this case, if the inner
diameter of venturi is more narrowed, the flow
speed is so much faster (refer to the equation). ※
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2. TROUBLESHOOTING
Problem Possible Cause Action
Engine will not crankLow battery voltage Charge or replace
Loose, corroded or damaged battery cable
Repair or replace
Faulty starter or open circuit
Faulty ignition switch or blown fuseRepair or replace
Poor engine ground Repair
Engine cranks too
slowLow battery voltage Charge or replac
Loose, corroded or damaged battery cable
Repair or replace Faulty starter
Starter does not
stopFaulty starter
Faulty ignition switch Replace
Engine cranks
normally, but does
not startBroken pinion gear or faulty starter
Replace the starter
Broken flywheel ring gear Replace
Open circuit Repair