## 5 Conclusions  
To bridge the gap of the low-power holding mechanism in the all-electric subsea gate valve actuator of the subsea production system, minimize the power consumption and cable number for  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter Description** & **Symbol** & **Optimal Solution** \\ \hline Radius of the actuator working cavity & \(r_{1}\) & 150 mm \\ Radius of the notch of the locking ring & \(r_{2}\) & 150 mm \\ Radius of the locking tab & \(r_{3}\) & 10 mm \\ Center distance between the actuator working cavity and the & \(l\) & 30 mm \\  
control and to improve the open-position keeping performance of all-electric subsea gate valve actuator, this paper proposed a novel low-power holding mechanism for the all-electric subsea gate valve actuator which can be applied to all-electric subsea gate valve actuators with various valve sizes and process pressure ratings. The paper also created mechanical and kinematic models, respectively, with regard to design variables, including the radius of the actuator working cavity \(r_{1}\), the radius of the notch of the locking ring \(r_{2}\), the radius of the locking tab \(r_{3}\), the center distance between the actuator working cavity and the locking ring notch \(l\), and the radial deflection angle of the center of the locking ring notch \(\alpha\). Based on these analytic models, the variable effects on the lockable maximum load of the closing spring and the permissible stroke of the locking tab were analyzed. The parameter adjustment method was illustrated to satisfy the design criterion that the working stroke of the locking tab \(L\) should not exceed the permissible stroke of the locking tab \([L]\). The detailed conclusions are as follows:  
* The proposed low-power holding mechanism is driven by the electromagnet and combines spiral transmission and cam-like transmission to convert the axial force of the closing spring into circumferential force to minimize the output force required as well as the number of the actuator's control cables, to improve the reliability and feasibility of the holding mechanism. The proposed low-power holding mechanism only requires a holding force of approximately 2%-7% of the maximum load of the closing spring to keep the valve open. * With a given output force of the electromagnet, the lockable maximum load the low-power holding mechanism can be increased by increasing \(r_{2}\) or decreasing \(r_{3}\), \(l\) and \(\alpha\). In the design space, the variable sensitivities of the lockable maximum load increases with the increase in \(r_{2}\) or the decrease in \(r_{3}\), \(l\) and \(\alpha\); the lockable maximum load is most sensitive to \(l\) and after that come \(\alpha\), \(r_{2}\) and \(r_{3}\) with regard to the average sensitivities in the design space. * The permissible stroke of the locking tab increases with the increase in \(r_{1}\), \(l\) and \(\alpha\) or the decrease in \(r_{2}\) and \(r_{3}\). In the design space, the variable sensitivities of the permissible stroke increase with the increase in \(r_{3}\) or the decrease in \(r_{2}\), \(l\) and \(\alpha\); the sensitivity of the permissible stroke to \(r_{1}\) remains on the lowest level in the full range; with regard to the average sensitivities of the permissible stroke, the most sensitive variable is \(\alpha\) and after that \(l\), \(r_{3}\), \(r_{2}\) and \(r_{1}\). * The design criterion is that the working stroke of the locking tab \(L\) should not exceed the permissible stroke of the locking tab \([L]\). The parameters can be adjusted to satisfy the criterion considering the variable sensitivities meanwhile minimizing the effect on the lockable maximum load. In the given case, the final parameter set of the low-power holding mechanism is: \(r_{1}\) = 150 mm, \(r_{2}\) = 150 mm, \(r_{3}\) = 10 mm, \(l\) = 30 mm and \(\alpha\) = 39.31\({}^{\circ}\), with a lockable maximum load of the closing spring of 71.44 kN.