VNT (Variable Nozzle Turbocharger

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1. Ring 2. Lever 3. Vacuum capsule 4. Vacuum circuit 5. Vacuum regulator 6. Guide rail 7. Vacuum circuit, vacuum pump

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VNT (Variable Nozzle Turbine)

The turbocharger is equipped with VNT technology, which makes it possible to combine the fast response of a small turbocharger with the high capacity of a large unit. The positions of the vanes in the turbine housing are varied by means of a vacuum generated by a vacuum pump which is driven by the exhaust camshaft. This means that the turbine inlet area, and the gas speed and angle of incidence against the turbine are varied for best effect. – A small flow area gives high exhaust gas speed and an angle of incidence which gives good low speed torque. The vane opening is at a minimum. – When the vane opening is at a maximum, this gives large flow area, which permits a wide working range for the turbo. The exhaust mass flow is now at its greatest. – The vacuum capsule rod is joined to a movable ring. The movable vanes are installed on the moving ring. When the ring moves, the position of the vanes is affected. – The vacuum capsule is connected to the vacuum circuit. The pressure supplied to the capsule is regulated by a solenoid valve controlled by a signal from the engine control unit.