## 3 Product Manufacturing and Performance Evaluation  
The diameter of the magnetic coil was \(\Phi\)0.3, and 36.5 layers \(*\) 10 steps were wound on the bobbin to manufacture the magnetic coil winding as shown in Figure 17a. Figure 17b is a permanent magnet made of Nd-Fe-B material in N-50H standard and manufactured in 4 divisions. As shown in Figure 17c, a coil assembly was fabricated by assembling a four-part permanent magnet instead of the lower case of the conventional TCV. A permanent magnet TCV was fabricated, as shown in Figure 17d, to experimentally confirm the performance evaluation of the actual vehicle condition by applying the total electromagnetic force and hydraulic pressure of the TCV.  
As shown in Figure 18, the experimental device to check the total electromagnetic force of TCV uses a 1-ton servo press to control the stroke, which is the distance between plunger and sol-seat. From the simulation results in Figures 13 and 16, the total electromagnetic force of TCV was confirmed to be less than 50N, and a load cell capable of measuring up to 50N was mounted on the servo press. In addition, a power supply device was prepared to check the total electromagnetic force for each current. Conventional TCV and permanent magnet TCV were manufactured and tested. Figure 19a is the result of comparing the total electromagnetic force for each current at stroke 0 mm with simulated and experimental  
Figure 16: Total electromagnetic force for each stroke in the permanent magnet TCV.  
Figure 15: Permanent magnet TCV: (**a**) magnetic flux density at \(-1.4\) A; (**b**) magnetic field strength at \(-1.4\) A; (**c**) magnetic flux density at \(-3.4\) A; (**d**) magnetic field strength at \(-3.4\) A.  
values. Figure 19b shows the total electromagnetic force at a stroke of 0.30 mm. It was confirmed that the total electromagnetic force for each current at 0 mm and 0.30 mm strokes was similar to the simulated and experimental values. The total electromagnetic force of permanent magnet TCV and the electromagnetic force of conventional TCV was similar at 3.4 A. The permanent magnet TCV has a magnetic force of about 7.0 to 7.3 N between the armature and the magnet core even if the current is applied and then cut off, so it was confirmed that the sol-seat flow path could not be opened. In addition, it was confirmed that a reverse current of \(-0.9\) to \(-2\) A was required to open the flow path of the sol-seat.  
Figure 19: Comparison of FEA and experiment results: (**a**) 0 mm stroke; (**b**) 0.3 mm stroke.  
Figure 17: Manufacture of the permanent magnet TCV: (**a**) magnet coil winding; (**b**) permanent magnetic; (**c**) coil assembly; (**d**) TCV.  
In order to verify the functioning of the TCV in real vehicle conditions, the performance tests of conventional TCVs and permanent magnet TCVs were performed using hydraulic performance test equipment, as shown in Figure 20. The test condition is that a TCV with 60 bar hydraulic pressure is applied. Check that the pressure change is less than 2 bar for 30 s after 5 s of stabilization time. Figure 21a is the hydraulic performance test result of the conventional TCV. To operate the TCV at a hydraulic pressure of 60 bar, 3.4 A was applied and the current was lowered to 1.5 A to minimize heat generation of the magnetic coil. In the section where the flow path was closed, it was necessary to continuously supply a current of 1.5 A. Figure 21b shows a hydraulically applied permanent magnet TCV, which applied current to de-energize the TCV as soon as it was activated. Even if the current was cut off, the flow path was closed by the magnetic force of the permanent magnet, and a reverse current was applied to open the closed flow path. Therefore, it was found that the permanent magnet TCV satisfies the function of the conventional TCV even if it does not continuously supply current after the initial operation.