Description
(1) variable geometry turbocharger
"a" exhaust turbine mobile fins control rod
"b" black 5-way connector
"A" turbocharger inlet
"B" exhaust gas inlet
"C" exhaust gas outlet
"D" turbocharger outlet
Suppliers
- Variable geometry control actuator: CONTINENTAL
- Turbocharger: MITSUBISHI
Role
The variable geometry turbocharger provides a constant pressure whatever the operating conditions
Role of the variable geometry turbocharger
- To increase the speed of the exhaust gases which strike the turbine at low engine speeds
- To reduce the speed of the exhaust gases which strike the turbine at high engine speeds
- To adapt the turbine to a variation in exhaust gas flow
Function: Turbocharger
The engine is turbocharged by a variable geometry turbocharger controlled by the engine ECU via a variable geometry control actuator
The turbocharger's position copy sensor (integral to the variable geometry control actuator) indicates precisely the exact position of the mobile blades of the exhaust turbine
"A" turbocharger inlet
"B" exhaust gas inlet
"C" exhaust gas outlet
"D" turbocharger outlet
"E" filtered inlet air
"F" filtered and compressed inlet air
"G" exhaust gas
"a" exhaust turbine mobile fins control rod
"b" black 5-way connector
"c" variable geometry control actuator (with integral position copy sensor)
"d" exhaust turbine mobile fins control rod mounting finger
"e" mobile drive plate
"f" mobile fins
"g" exhaust turbine
"h" fin lever
"j" inlet air compressor
The turbocharger is made of two separate chambers
- A chamber connected to the engine exhaust function
- A chamber connected to the engine inlet function
The exhaust turbine and the inlet air compressor are joined to each other by a shaft
The turbine, activated by the exhaust gas, drives the compressor which compresses the inlet air
"d" exhaust turbine mobile fins control rod mounting finger
"e" mobile drive plate
"f" mobile fins
"h" fin lever
The variable geometry control actuator changes the position of the mobile drive plate via the exhaust turbine mobile fins control rod
The change in position of the mobile drive plate causes the fins to pivot
Role of the rotation of the fins in respect of their different axes
- Variation of the inlet section of the exhaust gases onto the exhaust turbine
- More precise direction of the exhaust gases onto the exhaust turbine
The regulation of the boost pressure is progressive and is managed by the engine management ECU mapping
NoteThe mobile fins are in the open position when the variable geometry control actuator is not commanding the exhaust turbine mobile fins control rod
WarningBefore stopping the engine, wait for the engine speed to drop to idle; failure to comply with this condition will entail the destruction of the turbocharger over time (lack of lubrication)
Operation at low engine speed
"f" mobile fins
"g" exhaust turbine
At low engine speed the kinetic energy of the exhaust gases is weak
- The variable geometry turbocharger increases the kinetic energy of the exhaust gases by decreasing the section through which the exhaust gases must pass
- Furthermore the mobile fins ("f") in the closed position precisely direct the exhaust gases onto the exhaust turbine ("g")
NoteWith these two conditions the rotation speed of the exhaust turbine is accelerated at low engine speed
Operation at high engine speed
"f" mobile fins
"g" exhaust turbine
At high engine speed the kinetic energy of the exhaust gases is strong
- The variable geometry turbocharger decreases the kinetic energy of the exhaust gases by increasing the section through which the exhaust gases can pass
- Furthermore the mobile fins ("f") in the open position direct the exhaust gases onto the exhaust turbine ("g") in a less direct manner
NoteWith these two conditions the rotation speed of the exhaust turbine is reduced at high engine speed
Function: electric variable geometry control actuator
"k" secondary drive gear
"l" control shaft upper magnet guide
"m" upper cover (with 5 way connector)
"n" fixing screws (supply plate)
"p" supply plate
"q" reduction gear
"r" primary drive gear (electric motor)
"s" shaft (reduction gear)
"t" electric motor
"u" abutment washer (electric motor)
"v" exhaust turbine mobile fins control rod mounting finger
"w" control shaft mounting rod
"x" mounting rod guide
"y" lower cover (without connector)
"z" fixing clip (covers)
"aa" control shaft lower guide
"ab" return spring (control shaft)
"ac" control shaft
The supply coming from the upper cover "m" (with 5-way connector) powers the supply plate "p" which controls the electric motor "t"
The electric motor drives the primary drive gear of the electric motor "r"
The primary drive gear of the electric motor "r" drives the reduction gear "q"
The reduction gear "q" drives the secondary drive gear "k"
The secondary drive gear "k" via the control shaft "ac" and the control shaft mounting rod "w" actions the exhaust turbine mobile fins control rod mounting finger "v"
The variable geometry turbocharger position copy sensor is incorporated in the supply plate "p"
The engine management ECU sends a control signal in the form of an OCR to the control electronics
Control signal
- Reference position: OCR 90%
- Position with blades open (operation at high engine speed): OCR 90%
- Position with blades closed (operation at low engine speed): OCR 10%
"H" maximum opening position of the mobile fins (minimum relative outlet pressure of the variable geometry turbocharger)
"J" minimum opening position of the mobile fins (maximum relative outlet pressure of the variable geometry turbocharger)
"K" open cycle ratio (OCR) controlling the variable geometry control actuator (%)
"L" angular position of the control shaft mounting rod (in degrees)
"M" outlet pressure of the variable geometry turbocharger (relative pressure in bars)
"N" open cycle ratio (OCR) controlling the variable geometry control actuator (%)
NoteDigital signal of type Open Cycle Ratio (OCR)
Electrical features
Data: control motor
| description | minimum tolerance | nominal value | maximum tolerance |
|---|---|---|---|
| supply voltage | 8 V | 12 V | 18 V |
| supply current | 2A | 3A | 4A |
| resistance | - | 4,3 ohms | - |
Position copy sensor specifications
| description | minimum tolerance | nominal value | maximum tolerance |
|---|---|---|---|
| supply voltage | 4,5 V | 5 V | 5,5 V |
| supply current | - | 7 mA | -- |
Connecter (position repeat sensor)
| channel n° | allocation of the tracks of the connector |
|---|---|
| 1 | Power supply 5 V (position repeat sensor) |
| 2 | earth (position repeat sensor) |
| 3 | signal (position repeat sensor) |
| 4 | air and fuel supply - the engine |
| 5 | air and fuel supply + the engine |
Programming/initialisation
Programming is necessary if the component is replaced