SECTION 1 - GENERAL SPECIFICATIONS 15 F2B CURSOR EURO 4 ENGINES Print P1D32C002 E Base - September 2006 Actuator Figure 19 71834 1. Air inlet - 2. Gasket - 3. Piston - 4. External spring - 5. Internal spring control disc - 6. Internal spring - 7. O-ring - 8. Spring holder - 9. Limit stop - 10. Dust seal - 11. Control rod. Figure 20 [bar] Stroke [mm] 72421 a Gradient characterized by the effect of the external spring (4, Figure 19). b Gradient characterized by the effect of the external (4, Figure 19) and internal (6) springs.
Working principle (See Figure 19) The actuator piston, connected to the drive rod, is controlled with the compressed air introduced through the air inlet (1) on the top of the actuator. Modulating the air pressure varies the movement of the piston and turbine control rod. As the piston moves, it progressively compresses the external spring (4) until the base of the piston reaches the disc (5) controlling the internal spring (6). On further increasing the pressure, the piston, via the disc (5), interferes with the bottom limit stop (10). Using two springs makes it possible to vary the ratio between the piston stroke and the pressure.
Approximately 85% of the stroke of the rod is opposed by the external spring and 15% by the internal one. Solenoid valve for VGT control This N.C. proportional solenoid valve is located on the left-hand side of the crankcase under the turbine. The electronic control unit, via a PWM signal, controls the solenoid valve, governing the supply pressure of the turbine actuator, which, on changing its position, modifies the cross-section of the flow of exhaust gases onto the blades of the impeller and therefore its speed. The resistance of the coil is approx. 20-30 Ohms.