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The VAMPIRE model has already been used for obtaining figure 13. This figure compares the results obtained while varying the pipe length. As can be seen, the results between cases vary largely. It can also be observed that if the peak stiffness that appears during the transition between static and dynamic stiffness reaches near one of the vehicle vibration modes, it may produce a significant comfort reduction.

Figure 13 The VAMPIRE model has already been used for obtaining figure 13. This figure compares the results obtained while varying the pipe length. As can be seen, the results between cases vary largely. It can also be observed that if the peak stiffness that appears during the transition between static and dynamic stiffness reaches near one of the vehicle vibration modes, it may produce a significant comfort reduction.

Related Figures (15)

Figures 1 and 2 show two photographs where the main components of a pneumatic suspension installe on a bogie can be seen. Figure 1.- Air spring and emergency spring.
Figures 1 and 2 show two photographs where the main components of a pneumatic suspension installe on a bogie can be seen. Figure 1.- Air spring and emergency spring.
Figure 2.- Auxiliary air chamber and pipe.
Figure 2.- Auxiliary air chamber and pipe.
Figure 3.- ASTB Schematic, forces and displacements.
Figure 3.- ASTB Schematic, forces and displacements.
Figure 4.- Air spring-emergency spring-pipe-auxiliary air chamber assembled on the ASTB
Figure 4.- Air spring-emergency spring-pipe-auxiliary air chamber assembled on the ASTB
Figure 5.- Dynamic stiffness (Pressure 4 bar, Pipe interior diameter of 38 mm)
Figure 5.- Dynamic stiffness (Pressure 4 bar, Pipe interior diameter of 38 mm)
Figure 6.- Dynamic stiffness of the set. Effect of the pipe diameter. Pressure 4 bar, amplitude 1 mm.
Figure 6.- Dynamic stiffness of the set. Effect of the pipe diameter. Pressure 4 bar, amplitude 1 mm.
Figure 7.- Dynamic stiffness of the set with pipe A. Effect of the pipe and chamber. Pressure 4 bar.
Figure 7.- Dynamic stiffness of the set with pipe A. Effect of the pipe and chamber. Pressure 4 bar.
Figure 8.- Dynamic stiffness of the set with pipe A. Effect of a calibrated orifice on the pipe. Pressure 4 bar, amplitude 0.5 mm.
Figure 8.- Dynamic stiffness of the set with pipe A. Effect of a calibrated orifice on the pipe. Pressure 4 bar, amplitude 0.5 mm.
Figure 10.- Comparison of the results between the different models Asan be seen, all three models have different degrees of complexity. Figure 10 compares the predictions provided by the different theoretical models.
Figure 10.- Comparison of the results between the different models Asan be seen, all three models have different degrees of complexity. Figure 10 compares the predictions provided by the different theoretical models.
Figure 11 shows the experimental results obtained in other cases along with their corresponding theoretical predictions provided by the VAMPIRE or GENSYS model. As can be seen, the provided theoretical results are very close to the experimental ones.
Figure 11 shows the experimental results obtained in other cases along with their corresponding theoretical predictions provided by the VAMPIRE or GENSYS model. As can be seen, the provided theoretical results are very close to the experimental ones.
From the analysis above, it can be concluded that the characteristics of the pneumatic system affect comfort in a large degree. Likewise, it can be concluded that the use of a model that enables to properly represent the behaviour of the pneumatic system in the entire frequency range is required for performing comfort predictions.
From the analysis above, it can be concluded that the characteristics of the pneumatic system affect comfort in a large degree. Likewise, it can be concluded that the use of a model that enables to properly represent the behaviour of the pneumatic system in the entire frequency range is required for performing comfort predictions.
Figure 14.-Normalized comfort parameter for different values of C. Level of oscillations L0 As can be seen in this particular case, the C parameter, which is able to achieve good levels of comfort at the two measuring points is around 0.65: 10°. Figure 15 is obtained if the excitation is doubled. As can be seen, if the C obtained in the previous case is used, the level of comfort is not the optimum (the optimum level that can be achieved is around 1.36 and when calculating C=0.65- 104 we obtain 2.35).
Figure 14.-Normalized comfort parameter for different values of C. Level of oscillations L0 As can be seen in this particular case, the C parameter, which is able to achieve good levels of comfort at the two measuring points is around 0.65: 10°. Figure 15 is obtained if the excitation is doubled. As can be seen, if the C obtained in the previous case is used, the level of comfort is not the optimum (the optimum level that can be achieved is around 1.36 and when calculating C=0.65- 104 we obtain 2.35).
Figure 15.-Normalized comfort parameter for different values of C. Level of oscillations 2xL0 In order to solve this problem, we propose to insert a calibrated orifice inside the pipe whose opening will be dependent on the pressure. By choosing a proper opening, the system can achieve a lineal property. This way, the above mentioned problem may be avoided and optimum values of comfort achieved that are independent of the rail irregularity level. The system’s non-lineal property is due to the ratio between the pressure drop (AP) in the pipe and the air speed (v):
Figure 15.-Normalized comfort parameter for different values of C. Level of oscillations 2xL0 In order to solve this problem, we propose to insert a calibrated orifice inside the pipe whose opening will be dependent on the pressure. By choosing a proper opening, the system can achieve a lineal property. This way, the above mentioned problem may be avoided and optimum values of comfort achieved that are independent of the rail irregularity level. The system’s non-lineal property is due to the ratio between the pressure drop (AP) in the pipe and the air speed (v):
Figure 16.-Variable opening valve
Figure 16.-Variable opening valve
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EngineeringVehicle suspension
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