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Fig. 5. A VNT system with with vane and crank that convert translational movement of diaphragm to rotational movement of the vanes the external perturbations involved in the pneumatic actuator operation. These perturbations are namely due to aerodynamic force acting on the vanes of the VNT. Modeling of this force has not been addressed in the literature. Some work has been done by Namba et al. (2009) to predict aerodynamic force on the oscillating blades. An emperical model for the aerodynamic force has been addressed in this work. Angle of all the vanes in the VNT system is controlled by an electro-pneumatic actuator. All vanes moves together and they are connected to a crank via a unison ring. Crank transfer translational movement of the diaphragm into rotational movement of the vanes. Fig.5 shows a variable nozzle turbocharger system with all the vanes with the reactional aero-dynamic force. Aero-dynamic force

Figure 5 A VNT system with with vane and crank that convert translational movement of diaphragm to rotational movement of the vanes the external perturbations involved in the pneumatic actuator operation. These perturbations are namely due to aerodynamic force acting on the vanes of the VNT. Modeling of this force has not been addressed in the literature. Some work has been done by Namba et al. (2009) to predict aerodynamic force on the oscillating blades. An emperical model for the aerodynamic force has been addressed in this work. Angle of all the vanes in the VNT system is controlled by an electro-pneumatic actuator. All vanes moves together and they are connected to a crank via a unison ring. Crank transfer translational movement of the diaphragm into rotational movement of the vanes. Fig.5 shows a variable nozzle turbocharger system with all the vanes with the reactional aero-dynamic force. Aero-dynamic force

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A solenoid actuator in three different configurations is shown in the Fig.2. Figure on the left shows that actuator chamber is con- nected to the vacuum. Figure in the center shows that plunger is in equilibrium. Figure on the right shows that actuator chamber is connected to atmosphere. Modeling of the EPC is not the aim of this study. See Moraal (1999) and Galindo et al. (2009) for more comprehension. Fig. 2. Solenoid actuator shown for different working positions
A solenoid actuator in three different configurations is shown in the Fig.2. Figure on the left shows that actuator chamber is con- nected to the vacuum. Figure in the center shows that plunger is in equilibrium. Figure on the right shows that actuator chamber is connected to atmosphere. Modeling of the EPC is not the aim of this study. See Moraal (1999) and Galindo et al. (2009) for more comprehension. Fig. 2. Solenoid actuator shown for different working positions
‘ig. 1. A complete electro-pneumatic actuator with source reservoir and turbocharger is shown. A physical model of a single acting pneumatic actuator with pressure regulator, is presented in this section. Pressure is regu- lated, in one of the actuator chamber while keeping the pressure constant in the other chamber (See for example Moraal (1999) and Galindo et al. (2009)). Physical model of the pneumatic ac- tuator with controlled pressure in both chambers has also been developed for control by Messina et al. (2005) and Laghrouche et al. (2005) etc. Electro-pneumatic actuator can be divided into two parts: Pressure regulator/Electro-pneumatic pressure converter (EPC) and a pneumatic air valve. A complete dia- gram of the electro-pneumatic actuator with a variable nozzle turbocharger assembled with its diaphragm is shown in Fig.1.
‘ig. 1. A complete electro-pneumatic actuator with source reservoir and turbocharger is shown. A physical model of a single acting pneumatic actuator with pressure regulator, is presented in this section. Pressure is regu- lated, in one of the actuator chamber while keeping the pressure constant in the other chamber (See for example Moraal (1999) and Galindo et al. (2009)). Physical model of the pneumatic ac- tuator with controlled pressure in both chambers has also been developed for control by Messina et al. (2005) and Laghrouche et al. (2005) etc. Electro-pneumatic actuator can be divided into two parts: Pressure regulator/Electro-pneumatic pressure converter (EPC) and a pneumatic air valve. A complete dia- gram of the electro-pneumatic actuator with a variable nozzle turbocharger assembled with its diaphragm is shown in Fig.1.
Fig. 3. Experimental curve showing hysteresis between actuator position and pressure.
Fig. 3. Experimental curve showing hysteresis between actuator position and pressure.
Fig. 4. Identification of friction parameters of Dahl model
Fig. 4. Identification of friction parameters of Dahl model
Fig. 6. Three dimensional plot showing the equivalent force on the vanes as a function of vane opening and pressure ration across turbine
Fig. 6. Three dimensional plot showing the equivalent force on the vanes as a function of vane opening and pressure ration across turbine
Fig. 7. Applied pressure to the actuator for 1OOORPM Model is simulated in Matlab/Simulink and compared with experimental results provided by HTT at two different engine operating conditions. Test were carried out on a test bench with sensors that capture actuator pressure, diaphragm posi- tion, pressure at the inlet and outlet of turbine, and torque on the crank due to aero-dynamic force. All the parameters measured are shown in the Fig.1. Fig.7—11 show the simulation
Fig. 7. Applied pressure to the actuator for 1OOORPM Model is simulated in Matlab/Simulink and compared with experimental results provided by HTT at two different engine operating conditions. Test were carried out on a test bench with sensors that capture actuator pressure, diaphragm posi- tion, pressure at the inlet and outlet of turbine, and torque on the crank due to aero-dynamic force. All the parameters measured are shown in the Fig.1. Fig.7—11 show the simulation
Fig. 8. Position of the actuator diaphragm to produce the speed of 1000RPM
Fig. 8. Position of the actuator diaphragm to produce the speed of 1000RPM
load. Input to the simulator is pressure coming from the pres- sure regulator, which is shown in Fig.7. Applied pressure is dif- ferential pressure across diaphragm. Spring inside the actuator is in pre-compressed form, difference of 120kPa is required to compensate this force. Fig.8 shows the diaphragm position for the applied pressure. Fig.9 represents vane opening angle for different diaphragm positions. Crank angle has the minimum offset of 4 degree. Corresponding aero-dynamic force is shown in Fig.10 which is maximum when vanes are close. Deviation between measured and simulation results can be seen, this is due to the reason that simulation results are obtained from linear fitting of experimental results. In the Fig.11 hysteresis effect has been shown for applied pressure and diaphragm position. Comparison between simulation model and experimental re- sults confirms the effectiveness of the model with little devi- ation when vanes are completely close. The reason is that there may be some perturbation forces which are not considered into account. Fig. 9. Crank angle for different diaphragm positions with offset angle of 4.2
load. Input to the simulator is pressure coming from the pres- sure regulator, which is shown in Fig.7. Applied pressure is dif- ferential pressure across diaphragm. Spring inside the actuator is in pre-compressed form, difference of 120kPa is required to compensate this force. Fig.8 shows the diaphragm position for the applied pressure. Fig.9 represents vane opening angle for different diaphragm positions. Crank angle has the minimum offset of 4 degree. Corresponding aero-dynamic force is shown in Fig.10 which is maximum when vanes are close. Deviation between measured and simulation results can be seen, this is due to the reason that simulation results are obtained from linear fitting of experimental results. In the Fig.11 hysteresis effect has been shown for applied pressure and diaphragm position. Comparison between simulation model and experimental re- sults confirms the effectiveness of the model with little devi- ation when vanes are completely close. The reason is that there may be some perturbation forces which are not considered into account. Fig. 9. Crank angle for different diaphragm positions with offset angle of 4.2
Fig. 10. Aero-dynamic force acting on the vanes with complete engine cycle to produce 1000RPM
Fig. 10. Aero-dynamic force acting on the vanes with complete engine cycle to produce 1000RPM
Fig. 11. Hysteresis observed in the actuator for the ramp test for 100ORPM
Fig. 11. Hysteresis observed in the actuator for the ramp test for 100ORPM
Fig. 12. Applied pressure to the actuator in the form of pyramid
Fig. 12. Applied pressure to the actuator in the form of pyramid
Fig. 13. Position of the actuator diaphragm obtained for applied pressure
Fig. 13. Position of the actuator diaphragm obtained for applied pressure
Table A.l. Parameters values for the Pneumatic actuator used for simulation
Table A.l. Parameters values for the Pneumatic actuator used for simulation
Fig. 14. Crank angle for different diaphragm positions when applied pressure increase in steps Fig. 15. Aero-dynamic force acting on the vanes for pyramidal applied pressure
Fig. 14. Crank angle for different diaphragm positions when applied pressure increase in steps Fig. 15. Aero-dynamic force acting on the vanes for pyramidal applied pressure
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