Description
(1) variable geometry turbocharger, with position repeat sensor
"a" variable geometry control capsule
"b" 3-way black connector
"c" exhaust turbine mobile fins control rod
Supplier: Honeywell
"A" exhaust gas inlet
"B" turbocharger inlet
"C" turbocharger outlet
"D" exhaust gas outlet
"d" oil inlet
"e" water entry
"f" oil outlet
"g" coolant outlet
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 that hit the turbine at low engine speeds
- To reduce the speed of the exhaust gases that hit the turbine at high engine speeds
- To adapt the turbine to a variation in the flow of the exhaust gases
Function
The engine is turbocharged by a variable geometry turbocharger controlled by the engine management ECU by means of a proportional electrovalve
"A" exhaust gas inlet
"B" turbocharger inlet
"C" turbocharger outlet
"D" exhaust gas outlet
"a" variable geometry control capsule
"b" 3-way black connector (position repeat sensor)
"c" exhaust turbine mobile fins control rod
"h" inlet air compressor
"j" mobile fins
"k" exhaust turbine
"l" fin lever
"m" mobile drive plate
The turbocharger consists 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
"c" exhaust turbine mobile fins control rod
"j" mobile fins
"l" fin lever
"m" mobile drive plate
The variable geometry control capsule changes the position of the mobile drive plate by means of a control rod
The change in position of the mobile drive plate causes the fins to pivot
The rotation of the mobile fins in relation to their respective axis permits
- Variation of the inlet section of the exhaust gases onto the exhaust turbine
- More precise direction of the exhaust gases onto the exhaust turbine
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
"j" mobile fins
"k" 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
- In addition the movable vanes "j" in the closed position accurately direct the exhaust gases onto the exhaust turbine "k"
NoteWith these two conditions the rotation speed of the exhaust turbine is accelerated at low engine speed
Operation at high engine speed
"j" mobile fins
"k" 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
- In addition the movable vanes "j" in the open position direct the exhaust gases on to the exhaust turbine "k" less accurately
NoteWith these two conditions the rotation speed of the exhaust turbine is reduced at high engine speed
Electrical features
| designation | minimum tolerance | nominal value | maximum tolerance |
|---|---|---|---|
| supply voltage: position repeat sensor | 4,5 V | 5 V | 5,5 V |
| supply current: position repeat sensor | - | 7 milliamps | 10 milliamps |
| output impedance: position repeat sensor | - | 1 ohm | 10 ohms |
"E" control vacuum (mmHg)
"F" position of the control rod of the mobile fins of the exhaust turbine (mm)
| position of the rod | control vacuum | control vacuum |
|---|---|---|
| 0 mm | 67 millibars | 50 mmHg |
| 1 mm | 93 millibars | 70 mmHg |
| 2 mm | 167 millibars | 125 mmHg |
| 3 mm | 203 millibars | 152 mmHg |
| 4 mm | 253 millibars | 190 mmHg |
| 5 mm | 300 millibars | 225 mmHg |
| 6 mm | 347 millibars | 260 mmHg |
| 7 mm | 400 millibars | 300 mmHg |
| 8 mm | 440 millibars | 330 mmHg |
| 9 mm | 500 millibars | 375 mmHg |
| 10 mm | 547 millibars | 410 mmHg |
| 11 mm | 600 millibars | 450 mmHg |
"F" position of the control rod of the mobile fins of the exhaust turbine (mm)
"G" position copy signal (volts)
| position copy signal | position of the rod |
|---|---|
| 1 V | 10 mm |
| 2 V | 6,3 mm |
| 3 V | 2,5 mm |
| 3,75 V | 0 mm |
| channel number | allocation of channels of connector |
|---|---|
| 1 | earth |
| 2 | signal: position repeat sensor |
| 3 | Power supply 5 V |
Programming/initialisation
Not applicable