# New Actuation Control for Hybrid Electromagnetic Valve Train
## 2 Structure and Working of the New Hybrid PMEMV  
The proposed EMV is to be placed in the cylinder head to control the intake and exhaust of the engine. Figure 1 shows the structure of the electronic valve that includes the springs, spring positioner, armature, permanent magnets, guiding coil, and valve. The armature in the valve body can freely move in the vertical direction. The magnetic passages on both sides of the electronic valve are individually coiled to generate electromagnetic force. The upper permanent magnets (UPM) and lower permanent magnets (LPM) are placed at the upper and lower sides of the armature. When the guiding coil is not energized, the armature is attracted to either the upper or lower magnets. When the guiding coil is energized, the armature will move away from the existing position, due to the spring force, and then be attracted to another magnet side. The opening and closing of the air valve will be achieved. With this electronic valve mechanism, the total stroke of the valve from closing to opening is 8 mm. Figure 2 shows the flux path during conditions when the guiding coil is energized and not energized. The magnetic flux of the PM travels via armature when the guiding coil is not energized, traveling via the bypass channel. Figure 1: Schematic diagram of permanent magnet electromagnetic composite electronic valve [15]. The working principle of the hybrid PMEMV is shown in Figure 3. The direction of the arrow is the direction of the magnetic circuit, and the thickness of the arrow signifies the magnitude of the magnetic force. Initially, during the zero-current condition, the direction of the upper magnetic circuit passes through the armature, as shown in Figure 3a. It means, that UPM exhibits a magnetic attraction force on the armature, which is higher than the spring force. Hence, the valve sustains, in its closing position, until the electromagnetic (EM) field is activated. When the EM circuit (guiding coil) is energized, it diverts this magnetic flux from the armature to the bypass channel, as shown in Figure 3b,c. Therefore, the attraction force between the armature and the UPM is dropped, then the spring force of the lower spring mechanism is used to make the armature leave the UPM, and the air valve opening starts at this time. Next, the armature starts moving on the opposite side of the existing position due to spring force. As shown in Figure 3d, when the armature is affected by the spring force of the spring mechanism and leaves the UPM and reaches the LPM, the armature is attracted by the permanent magnet at the LPM, and the air valve is now fully opened. The hybrid electronic valve is a symmetrical design. Therefore, the direction of the magnetic circuit during the movement of the armature from the lower apex to the upper apex is also followed in a similar process, as shown in Figure 3d-f. The operation of the electronic valve must be controlled by precise current pulses, to drive the armature to move effectively and achieve the opening and closing of the  
Figure 3: Magnetic circuit diagram of the EM valve: (**a**) the armature is attracted by the upper magnet; (**b**) the magnetic flux is directed by the guiding coil; (**c**) the armature is released downward; (**d**) the armature is attracted by the lower magnet; (**e**) guided by the coil; (**f**) the armature is released upwards [15]. Figure 2: Magnetic circuit diagram of hybrid PMEMV: (**a**) without current; (**b**) with current [15]. electronic valve. Figure 4 shows the electronic valve operation cycle and the release current actuation timing. However, the above pulse signal is not effectively working due to the inadequate magnetic force of the PMs. Figure 5 shows the experimental results of the proposed guided EM valve displacement (mm) with the above control signal. When the current is given to the coil, the upper vertex permanent magnet attraction force on the armature is decreased, and then the armature is released downward due to the spring force.