# Effects of Valve, Armature, and Armature Pin Guidance on Diesel Injector Performance
## 2 Materials and Methods
### Experimental Method  
Experimental groups were established based on injector production expertise. The experiment focused on two variables:  
1. clearance between the valve and armature;
2. clearance between the armature and armature pin. Each variable was evaluated at three levels:  
* high clearance;
* low clearance;
* lowest clearance. While one variable was investigated, the other was maintained at medium clearance, allowing each factor to be examined independently. This approach resulted in a total of six experiments. Additionally, one experiment (group 4) was independently added as a reference group with both clearances set to medium. Other sub-components were manufactured to medium tolerance levels and were not considered variables; thus, they were not included as separate experimental groups. In total, seven different groups were formed. The details of these groups are presented in Table 1. The \"Research package\" column clarifies the purpose of each experiment, while the \"Group number\" column specifies the identifiers for the experimental groups. Each group consists of seven injectors, culminating in the production of 49 injectors. In groups 1, 2, and 3, the clearance between the armature pin and armature was set at a medium value, focusing solely on the effect of the clearance between the valve and armature. Conversely, in groups 5, 6, and 7, the clearance between the valve and armature was maintained at a medium value, exclusively examining the impact of the clearance between the armature and armature pin. Group 4 served as the reference group, with both clearances set to medium. Apart from the valve, armature, and armature pin, the spring, nozzle, and magnet group are other sub-components that directly impact injector function and spray characteristics. The critical parameters and dimensions of these parts were standardized at medium values for all injectors. The spring influences the armature's opening-closing behavior based on armature movement, while the magnet group electrically triggers this movement. Once the experimental groups were established, injector production commenced. All relevant sub-parts likely to affect performance were measured using calibrated precision measuring devices to ensure they were free of dents and scratches during assembly. Transition parameters were recorded during injector assembly, and final function and sealing tests were conducted. The diameter tolerance usage rates of the sub-parts are depicted in Figure 3. Given the variability in size and tolerance values of each part, these rates were used as a reference to analyze relationships between the experimental results. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Research Package**} & \multirow{2}{*}{**Group Number**} & \multicolumn{3}{c}{**Clearance between Valve and Armature**} & \multicolumn{3}{c}{**Clearance between Armature and Armature Pin**} \\ \cline{3-10}  & & **High** & **Medium** & **Low** & **Lowest** & **High** & **Medium** & **Low** & **Lowest** \\ \hline Effect of clearance & 1 & ✓ & & & & ✓ & & \\ between valve & 2 & & & ✓ & & ✓ & & \\ and armature & 3 & & & & ✓ & & ✓ & \\ \hline Reference group & 4 & & ✓ & & & & ✓ & & \\ \hline Effect of clearance & 5 & & ✓ & & & ✓ & & \\ between armature & 6 & & ✓ & & & & ✓ & \\ and armature pin & 7 & & ✓ & & & & & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Experimental groups. Figure 3: Diameter tolerance usage rates of experimental groups. The percentage values in Figure 3 represent each part's position within its total tolerance range, starting from the lower limit. For instance, the inner diameter of the valve in the first group is at 97% of its tolerance range from the lower limit. The outer diameter of the armature is marginally above the lower limit, at approximately 1% of the total tolerance. Both the armature's inner diameter and the armature pin's outer diameter are positioned at the intermediate value of 50%.