# Reliability Optimization Design of Diesel Engine System Based on the GO Method
## 2 Diesel Engine Reliability Modeling and Distribution Based on the GO Method
### Establishment of the GO Diagram Model for Diesel Engine System
#### 2.2.2 The GO Diagram Model of the Diesel Engine System  
The GO diagram model of the diesel engine system is established on the basis of the system analysis and GO diagram model building method. The diesel engine system involving multiple closed-loop feedback structures is complex and has many components. Thus, this paper adopts a two-level GO diagram for modeling [15]. First, the first-level GO diagram model is constructed, followed by the second-level GO diagram model, namely the GO diagram model of the diesel engine system.  
(1) The first-level GO diagram model of the diesel engine system  
The four sub-systems of the diesel engine, including the cooling system, lubrication system, fuel supply system, and inlet, exhaust, and turbocharge system, contain closed-loop feedback structures, as suggested by analyzing the structure, operating principle, and function of the diesel engine system. The first-level GO diagram model is built for the closed-loop feedback structures of the four sub-systems, as exhibited in Figure 3.  
(2) The GO model of the diesel engine system  
With the system analysis and Table 1, the first-level GO diagram model is integrated into the second-level GO diagram model to form the GO diagram of the diesel engine system, as illuminated in Figure 4. The first digit of the operator represents its number, and the second digit represents its type. The digit on the signal flow indicates its number. Signal flows 23, 27, 45, 128, and 129 are the power, cooling, lubrication, and exhaust functions of the diesel engine, and the output signal flows of the system, respectively.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Unit** & **Operator Number** & **Operator Type** & \(R_{i,old}\) & \(R_{i,min}\) & \(R_{i,max}\) & \(f_{i}\) \\ \hline Check valve & 82 & 1 & 0.999580 & 0.999 & 1 & 0.6 \\ Return pipe contact & 83 & 1 & 0.999300 & 0.999 & 1 & 0.6 \\ Fuel cooler & 84 & 1 & 0.997400 & 0.99 & 1 & 0.65 \\ Oil injector & 85 & 1 & 0.999400 & 0.999 & 1 & 0.75 \\ Float valve & 86 & 1 & 0.999600 & 0.999 & 1 & 0.6 \\ Expansion oil tank & 87 & 1 & 0.999800 & 0.999 & 1 & 0.6 \\ Cylinder cover gear & 88, 94 & 1 & 0.999750 & 0.999 & 1 & 0.6 \\ Camshaft & 89, 90, 95, 96 & 1 & 0.999750 & 0.999 & 1 & 0.6 \\ Valve & 91, 92, 97, 98 & 1 & 0.999000 & 0.999 & 1 & 0.6 \\ Air & 99 & 5 & 1.000000 & & & \\ Air filter & 100, 114 & 1 & 0.997600 & 0.99 & 1 & 0.65 \\ Inlet manifold & 101, 115 & 1 & 0.999100 & 0.999 & 1 & 0.6 \\ Four-input single-closed-loop & 102, 116 & 24B & & & & \\ Imk & 103, 117 & 1 & 0.999200 & 0.999 & 1 & 0.7 \\ Intercooler & 104, 118 & 1 & 0.997900 & 0.99 & 1 & 0.6 \\ Intake manifold & 105, 119 & 1 & 0.999100 & 0.999 & 1 & 0.6 \\ Cylinder & 107, 121 & 13 & 0.997000 & 0.99 & 0.999999 & 0.75 \\ Exhaust manifold & 109, 123 & 1 & 0.999100 & 0.999 & 1 & 0.6 \\ Mian exhaust pipe & 110, 124 & 1 & 0.999100 & 0.999 & 1 & 0.6 \\ Turbine & 111, 125 & 1 & 0.996000 & 0.999 & 0.999999 & 0.7 \\ Rotor spindle & 112, 126 & 1 & 0.999300 & 0.999 & 1 & 0.6 \\ Tail pipe & 113, 127 & 1 & 0.999100 & 0.999 & 1 & 0.6 \\ \hline \end{tabular}
\end{table}
Table 1: _Cont._Figure 4: GO diagram model of the diesel engine system.  
Figure 3: The first-level GO diagram model of the diesel engine system. (**a**) First-level GO diagram model of the cooling system; (**b**) First-level GO diagram model of the lubrication system; (**c**) First-level GO diagram model of the fuel supply system; and (**d**) First-level GO diagram model of the inlet, exhaust, and turbocharge system.