## 1 Introduction
### Structural Configurations of the APRV
Simulation Model for the Pressure Regulation Characteristics of the APRV of the Different Structural Configurations  
Based on the structural configurations of the APRV, the simulation model is established, and the pressure regulation characteristics are studied. To study all the structural configurations shown in Figure 2 in one simulation model, the AMESim simulation models of high-speed solenoid valves (Components SC_1 and SC_3,) and pedal valve (Component SC_2) are established. The simulations for the tests of the manual control mode, electronic control mode, coupled control mode and the switch between the control modes are done by switching the control signals of components SC_1, SC_2 and SC_3. The simulation model for the pressure regulation characteristics of the APRV is shown in Figure 5.  
The main structural parameters of the simulation model for the pressure regulation characteristics of the APRV of the different structural configurations in the ECPBS of commercial vehicles are shown in Table 5.  
To verify the correctness of the simulation model of the APRV, a series of tests are done on the test bench for the pressure regulation characteristics of the APRV of different structural configurations in the ECPBS of commercial vehicles, and the curves of the  
Figure 5: Simulation model for the pressure regulation characteristics of the APRV of the different structural configurations in the ECPBS of commercial vehicles. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Air Source Pressure**} & **Seal-Ring** & \multirow{2}{*}{**Hole Diameter**} & **Volume of** & \multirow{2}{*}{**Maximum Travel**} \\  & & **Diameter** & & **Control Cavity** & \\ \hline
**Values** & 0.7 MPa & 7 mm & 6 mm & 0.04 L & 0.24 mm \\ \hline
**Parameter** & Number of coil turns & Winding resistance & Spring rate & Preload force & Mass of the valve core \\ \hline
**Values** & 1000 & 50 Ohm & 2000 N/m & 10 N & 5 g \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Main structural parameters of the simulation model for the pressure regulation characteristics of the APRV of different structural configurations in the ECPBS of commercial vehicles. pressure regulation characteristics of the pressure regulator under manual control model and electronic control mode are shown in Figure 6.  
The experiments results and the simulation results show the same trends, similar response times and consistent key values; thus, the simulation model fits well with the test bench. The simulation is done by changing the control signals of components SC_1, SC_2 and SC_3, and the parameters of the simulations for each control condition are shown in Table 6.  
In Table 6, the signal value 0 is the deactivation signal, and signal value 1 is the activation signal. It is difficult to simulate the switch from the manual control mode to another mode. To simulate the insufficient pressure during manual-controlled braking, the maximum outlet pressure in the manual control mode is set to 0.3 MPa. In the simulation for the switch test between the control modes, the control mode is switched from the manual control mode to the electronic control mode or coupled control mode in 0.5 s. The simulation results are illustrated in Figure 7.  
Figure 6: Verification of the simulation model for the pressure regulation characteristics of the APRV of the different structural configurations in the ECPBS of commercial vehicles: (**a**) manual control and (**b**) electronic control. Figure 7: Simulation curves of the pressure regulation characteristics of the APRV of the different structural configurations in the ECPBS of commercial vehicles.