Experimental Study and Simulation Analysis on Electromagnetic Characteristics and Dynamic Response of a New Miniature Digital Valve

In order to get the better electromagnetic characteristics of the micro digital valve, the larger electromagnetic force should be obtained in the smaller electromagnetic structure.+e electromagnetic force directly determines the electromagnetic properties of the miniature digital valve.+e electromagnetic force test is studied in the paper.+e results of electromagnetic simulation results are basically consistent with the experimental results. +e simulation model is reliable and accurate. +e dynamic simulation results show that the dynamic characteristics of the miniature digital valve meet the requirements of the digital hydraulic technology. Design of the new micro digital valve is reasonable.


Introduction
Digital hydraulics technology has a potential to replace the proportional technology and the servo technology because of their superior properties, such as low cost, reliability, and insensitivity to contamination [1,2].Because the digital hydraulic system is composed of many digital valves, the size of the system is bigger than that of the proportional system and the servo system.erefore, the size of a single valve should be designed to be smaller to solve the problem.In addition, the micro high-speed digital valves are the key components of the digital hydraulics system.Fast response performance of the micro high-speed digital valves directly influences the control precision of the whole system.Electromagnetic force decides the response performance of the micro high-speed digital valves.How to obtain largest electromagnetic force in a smaller size is a key problem, which should be given more attention.
A large number of working mechanisms of electromagnetic characteristics of the high-speed valves have been studied [3][4][5].rough selection of different soft magnetic materials and structure parameters, larger magnetic force and lower power losses have been achieved by Tao et al. [6].Effects of electronic circuit on the magnetic field of a solenoid valve were studied by Angadi [7].e dynamic behavior of two different micro valves was measured by Luharuka et al. [8].
e dynamic response and power losses of high-speed solenoid injector were studied by Cheng et al. [9] by using a simplified model.e multiphysics modelling of a solenoid valve was established, and the multiphysics network simulation was done by Mutschler et al. [10].e dynamic response and the static electromagnetic characteristics of the solenoid valve were studied by Wang et al. [11] by using the simulation method.
e effects of current on speed response of a high-speed valve were developed by Topcu et al. [12].e integrated numerical-experimental approach which can be used to examine both the mechanical and hydraulic performance of the pilot valve was proposed by Ferrari et al. [13].e key factors of electromagnetic force of the solenoid valve were researched by Liu et al. [14].e highly accurate method for prediction of dynamic characteristics of a solenoid fuel injector was presented by Ando et al. [15].Energy consumption of the solenoid actuator and the in uence of di erent structure parameters on the response time were studied by Lantela et al. [16].
According to the above literatures, it can be concluded that electromagnetic force plays a key role in the micro highspeed digital valve.Structure parameters are crucial to the electromagnetic force.Although the researchers have done a lot of research work on electromagnetic force, they only focused on di erent driving parameters and structure parameters.
e objective of this paper is to research electromagnetic characteristics and dynamic response of the new miniature digital valve.e e ects of di erent parameters on magnetic properties and dynamic response are analyzed in the paper.e more detailed parameters can be obtained in [17]. 2 Advances in Materials Science and Engineering

Simulation Setting.
Accurate simulation models can make our calculation more accurate.In order to verify the accuracy of the model, we have adopted the verification method between experiment and simulation.In the simulation, we use the finite element method in [11,18].e simulation software of ANSYS Maxwell has been adopted to the simulation study [11,19].e grid models of the traditional valve and the novel valve are shown in Figures 3 and  4. In order to get more accurate simulation results, we use the more refined grid.e more detailed information and parameters of the simulation are obtained in Table 1 [17].

Testing Platform.
e testing platform of electromagnetic force was made up of the industrial personal computer, the current controller, the current collector, the control panel, force transducer, and the host computer, as is seen in Figure 5. Figures 6(a) and 6(b) show all the components and the whole structure of the micro high-speed digital valve.Electromagnetic force was transmitted from the valve spool to the force transducer through the guide rod [17].
e dynamic and static characteristics of the solenoid valve are related to the magnitude of the electromagnetic force, the greater the electromagnetic force, the better the characteristics of the micro digital valve.Using the electromagnetic force test platform, the test conditions can be adjusted by changing the magnitude of excitation current and air gap stroke.In order to verify the correctness of the simulation model and settings, the electromagnetic force of the miniature digital valve with 0.9 A test current, 400 coil turns, and 0.1 mm air gap stroke is tested.e simulation and test results are shown   Advances in Materials Science and Engineering in Figure 7. From Figure 7, it can be concluded that electromagnetic force rises along with the reduction of the air gap.e error between simulation and experiment is very small and less than 4 percent.erefore, the simulation is in agreement with the actual results, and the simulation model is reasonable and correct.

In uence of Di erent
Currents.e characteristics of electromagnetic eld determine the magnitude of electromagnetic force.e greater the magnetic eld line density of electromagnetic eld, the greater is the intensity of electromagnetic eld.e variation of magnetic line density and electromagnetic eld intensity under di erent excitation currents is studied in this paper.As shown in Figure 8, the excitation currents of 0.8 A and 1.2 A are taken, respectively, and the magnetic eld lines of force are shown in Figures 8 (a) and 8(b); the magnetic induction intensity nephogram of the electromagnetic eld is shown in Figure 9. e ohmic loss of the electromagnetic eld of the two micro valves under the same current is shown in Figure 10.As can be seen from Figures 8 and 9, the magnetic line density and magnetic induction of the electromagnetic eld rise with the increase of the excitation current.e ohmic loss of the new valve is smaller than that of the traditional valve.

Dynamic Characteristics.
e current rising speed of the electromagnet determines the dynamic characteristics of the micro solenoid valve.e faster the current rising speed, the better the dynamic characteristics.e rising speed of the current depends on the inductance of the electromagnet, and the inductance is related to the number of coils.As shown in Figure 11, as the number of coils increases, the in ection point of current rise appears more slowly, and when the current is stable, the currents are the same. is is because as the number of coils increases, the inductance of the electromagnet increases, impeding the rate of current change, thus reducing the rate of current rise.In order to obtain a higher current rising speed, the number of coil coils should be reduced appropriately.
e motion speed, displacement, and electromagnetic force of di erent coil loops are shown in Figures 12-14.Taking 1300 turns as an example, at 2.78 ms, the electromagnet begins to move with speed and displacement.At 3.61 ms, the speed reaches the maximum value, about 1.02 m/s.Since then, the velocity has decreased, and the velocity has decreased to 0 at 3.74 ms.Accordingly, the displacement has reached the maximum value of 0.3 mm.

Conclusion
In this paper, the simulation results are in good agreement with the experimental results of the miniature digital valve, and the simulation model is accurate.e electromagnetic characteristics and dynamic response are studied in the paper.
e smaller the coil number and the smaller the    Advances in Materials Science and Engineering inductance, the faster the current response of the electromagnet.Correspondingly, the faster the speed, the greater the displacement.erefore, under the same conditions, the coil turns should be reasonably reduced to improve the dynamic characteristics of the micro digital valve.
Data Availability e data used to support the ndings of this study are available from the corresponding author upon request.Advances in Materials Science and Engineering

2. 1
. e Novel Micro High-Speed Digital Valve.Unlike the traditional digital valve, the new micro digital valve adopts the spring top arrangement, as shown in Figure1.Compared with the traditional valve (as seen in Figure2), this new design increases the magnetic ux area and e ectively improves the electromagnetic force.

Figure 5 :
Figure 5: Testing platform of electromagnetic force.

Figure 7 :
Figure 7: Simulation and testing comparison of electromagnetic force of the two valves.

Table 1 :
Detailed information of Maxwell computation.