Role
The "engine vibration damping" function is for reducing the amount of engine idling noise and vibration being felt inside the passenger compartment
The "engine vibration damping" function operates via the diesel injection ECU which controls the piloted torque reaction rod electrovalves
The torque reaction rods, when piloted, provide a counter-torque to the engine, to absorb the noises and vibration noises coming from the engine
When they are not being piloted, the torque reaction rods absorb the movements relating to the engine torque
Description
The "engine vibration damping" function operates through the following components
- A diesel injection ECU
- 2 piloted torque reaction rods
- 2 piloted torque reaction rod electrovalves
- A vacuum pump
- A vacuum reserve
Diesel injection ECU
The diesel injection ECU sends an OCR type control frequency to the piloted torque reaction rod electrovalves
The diesel injection ECU recalculates the control frequency of the piloted torque reaction rod electrovalves to each engine combustion, that is 3 times per rotation
One period of the control signal for the piloted torque reaction rod electrovalves corresponds to one 120° rotation of the crankshaft
Each start of a period of the control signal for the piloted torque reaction rod electrovalves corresponds to the cylinder producing the combustion which is causing the vibrations that are retransmitted into the passenger compartment
For an engine idling speed varying between 600 and 1400 rpm, the OCR signal frequency oscillates between 30 and 70 Hz
Piloted torque reaction rod
Description
Key
- (1) rear piloted torque reaction rod
- (2) rear piloted torque reaction rod electrovalve
- (3) front piloted torque reaction rod
- (4) front piloted torque reaction rod electrovalve
Role
The role of the piloted torque reaction rods is to reduce the amount of engine idling noise and vibration being retransmitted into the passenger compartment
The piloted torque reaction rods reduce the forces that are retransmitted to the passenger compartment, by generating a force opposite to that transmitted by the engine idling (engine idling speed lower than 1400 rpm at a speed less than 20 km/h)
NoteThe piloted torque reaction rods operate in parallel to the conventional engine supports
NoteWhen the piloted torque reaction rod electrovalves are not being supplied, the vacuum chambers of the piloted torque reaction rods are being vented
Location
The front piloted torque reaction rod is installed between the gearbox and the front subframe crossmember
The rear piloted torque reaction rod is installed between the gearbox and the front subframe
Vacuum circuit
Role of the vacuum pump
The vacuum pump supplies the vacuum required for operating the following components
- Piloted torque reaction rod electrovalves
- Brake servo
- "Swirl" control electrovalve
Description
The vacuum pump is driven by the camshaft of the rear cylinder bank
(5) vacuum reserve supply
(6) vacuum reservoir
(7) vacuum pump
Location
The vacuum pump is situated on top of the rear cylinder head, gearbox end
Piloted torque reaction rod electrovalve
Role
The piloted torque reaction rod electrovalves are linked to the vacuum reserve (6)
The electrovalves create a vacuum in the vacuum chamber of the piloted torque reaction rods
Description
2-way electrical connector
- Line N° 1: 12 volts supply
- Line N° 2: control signal
Location
The electrovalves are located on top of the piloted torque reaction rods, front and rear
Principles of operation: piloted torque reaction rod
Placing the vacuum chambers of the piloted torque reaction rods under a vacuum
Key
- A: electrovalve venting
- B: link from the electrovalve to the vacuum reserve
- C: link from the electrovalve to the vacuum chamber
- D: electric piloting of the piloted torque reaction rod electrovalve
- (1) rear piloted torque reaction rod
- (2) rear piloted torque reaction rod electrovalve
- (3) front piloted torque reaction rod
- (4) front piloted torque reaction rod electrovalve
- (5) vacuum reserve supply
- (6) vacuum reservoir
- (7) vacuum pump
- (8) motor
- (9) front subframe
- (10) diesel injection ECU
The diesel injection ECU (10) sends a control signal to the electrovalves (2) and (4) which start the communication of the vacuum reserve (6) with the vacuum chambers of the piloted torque reaction rods (1) and (3)
The piloted torque reaction rods (1) and (3) generate a force opposite to that transmitted by the engine at idling speed
Venting of the vacuum chambers of the piloted torque reaction rods
Key
- A: electrovalve venting
- B: link from the electrovalve to the vacuum reserve
- C: link from the electrovalve to the vacuum chamber
- D: electric piloting of the piloted torque reaction rod electrovalve
- (1) rear piloted torque reaction rod
- (2) rear piloted torque reaction rod electrovalve
- (3) front piloted torque reaction rod
- (4) front piloted torque reaction rod electrovalve
- (5) vacuum reserve supply
- (6) vacuum reservoir
- (7) vacuum pump
- (8) motor
- (9) front subframe
- (10) diesel injection ECU
The diesel injection ECU (10) stops the control signal to the electrovalves of the piloted torque reaction rods (2) and (4)
The electrovalves (2) and (4) give the venting chambers of the piloted torque reaction rods (1) and (3) access to fresh air
The piloted torque reaction rods (1) and (3) absorb the movements relating to the engine torque
Piloting of a torque reaction rod
Key
- A: electrovalve venting
- B: link from the electrovalve to the vacuum reserve
- C: link from the electrovalve to the vacuum chamber
- E: force generated by the piloted torque reaction rod
- F: force generated by the engine
- (1) piloted torque reaction rod
- (2) piloted torque reaction rod electrovalve
- (6) vacuum reservoir
- (11) vacuum chamber
- (12) hydraulic resonator
- (13) silentblock
The piloted torque reaction rod electrovalve (2) is controlled by an OCR type signal sent by the diesel injection ECU
The piloted torque reaction rod electrovalve (2) links the vacuum reserve (6) to the vacuum chamber (11)
The pneumatic force is amplified by the hydraulic resonator (12)
The vacuum of the hydraulic resonator (12) generates a force E opposite and equal to the force F generated by the engine. the 2 forces cancel each other
The piloted torque reaction rods thus operate in a succession of vacuums and ventings of their vacuum chambers, so as to absorb the vibrations coming from the engine
Operation of the piloted torque reaction rod electrovalve
The piloted torque reaction rod electrovalve (2) is controlled by an OCR type signal sent by the diesel injection ECU
Solenoid valve not supplied
Key
- A: electrovalve venting
- B: link from the electrovalve to the vacuum reserve
- C: link from the electrovalve to the vacuum chamber
When the electrovalve is not being supplied, channel A is joined to channel C: the vacuum chamber of the piloted torque reaction rod is vented
Solenoid valve supplied
Key
- A: electrovalve venting
- B: link from the electrovalve to the vacuum reserve
- C: link from the electrovalve to the vacuum chamber
When the electrovalve is being supplied, channel B is joined to channel C: the vacuum reserve creates a vacuum in the vacuum chamber of the piloted torque reaction rod
Information permitting the diesel injection ECU to control the piloted torque reaction rod electrovalves
- Coolant temperature
- Engine speed
- Average engine torque indicated
- Vehicle speed
- Battery voltage
- FAP activation
- Gearbox position (in back-up mode)