Research on the Planetary Gear Deceleration Machine Design of a Novel Rapidly-Opening/Closing Actuator of Manual Valve

Failing to promptly close the valve whose circuits have been burnt out is one of the important causes leading to an amount of oil leakage after the Dalian oil pipeline explosion. Moreover, the opening/closing torque of the manual valves will be bigger due to no actions for a long time, corrosion, rust, etc. And the operators will stay in a dangerous environment for a long time and thus they will have life problems when there are abnormal conditions or accident conditions. This paper proposes a design idea of a novel rapidly-opening/closing actuator of a manual valve, in order to resolve the problem that how to open/close a manual valve rapidly. The research on the rapidly-opening/closing actuator of a manual valve should include the calculation of the opening/closing torque of the manual valve and the designs of the deceleration machine and the chuck. The output shaft of the deceleration machine connects with a chuck, while the chuck connects with the wheel of the valve. The work principle of the actuator is that a motor drives the rotation movement of the deceleration machine so as to realize the rapid opening/ closing of the valve. This paper mainly focuses on the design of the deceleration machine, wherein the structure of planetary gear is designed through the theoretical calculation and the computer-aided design method. The research of the method provides the design method and the technical support for the design of the rapidly-opening/closing actuator of the manual valve. The actuator could be employed to the safety prevention departments of the chemical industries after the successful design of the device. The device can be utilized to cope with the problem that how to open/close a manual valve with more rotating laps or in emergency conditions rapidly. Moreover, the accident rescue ability of the chemical industries will be further improved, and the loss of the accidents will be reduced.


Introduction
In chemical industrial enterprise, the valve is a very important control unit in a fluid delivery system. Failing to promptly close the valve whose circuits have been burnt out is one of the important causes leading to an amount of oil leakage after the Dalian oil pipeline explosion. Such as on July 16, 2010 in Dalian Xin'gang oil pipeline explosion and oil leakage accident, one of the important reasons was that oil burning damaged the power system and the power-driven valves had been disabled, then the operation personnel rushed into the third tank, spent more than one hour to rotate the valve over 8,000 circles by hands to close the valve completely. Finally, the oil leaking out of the tank stopped. The delay of the closing of the valve had induced a large amount of oil leakage and oil burning, which caused a huge loss in the accident and serious environment pollution. In addition, the operation personnel stayed in the dangerous environment for a long time to deal with the emergency, which also increased the possibility of casualties. Moreover, the opening/closing torque of the manual valves will be bigger due to no actions for a long time, corrosion, rust, etc.
In order to cope with the problem that how to open/close a manual valve rapidly, this paper mainly focuses on the structure design of the planetary gear deceleration machine through the theoretical calculation and the computer-aided design method. The research of the method provides the design method and the technical support for the design of the rapidly-opening/closing actuator of the manual valve.

Function principles
As shown in figure 1, the function principles of the rapidly-opening/closing actuator of a manual valve are that an accumulator (10) will supply the power for an electromotor(1), the power output from the electromotor transfer to a chuck(7) through a planetary gear deceleration machine deceleration. The chuck will drive the wheel of a manual valve (8) rotating to realize the rapid opening/ closing of the valve.

Summary of the planetary gear
The actuator selects the two grade-NGW-type planetary gear with higher efficiency, and the framework diagram is shown in Fig. 2, where a is the sun wheel, b is the ring gear, and c is the planetary wheel [1].

Design process
As shown in Fig.3, the design process includes four steps.
Adjust the gear ratio b aH i properly to convert C to be an integer, and to work out a Z . Then use the equations (2) and (3) to work out the number of the ring gear teeth b Z and the number of planetary wheel teeth c Z .
According to the different C values, we can obtain many groups of the number of the teeth, and we select an appropriate number of the teeth based on the size and other conditions.
(2) Strength calculation Calculate the centre distance according to the teeth contact strength: where j a is a calculation factor, which can be looked up according to σ is a gear contact fatigue limit, which can be looked up according to Table 2-80 [2].
The initial value of the gear modulus is: If the modulus is not a standard value, then the value is taken as the standard value (1, 1.25, 1.5, 2, 2.5, 3, 4, 5).
Then the actual gear center distance is:

Conclusion
The application of the planetary gear deceleration machine in the rapidly-opening/closing actuator of manual valve has the advantages of compact structure, light weight, high efficiency, a wide range of transmission ratio, etc. Because the output shaft and the input shaft of the rising stem gate valves are on the same straight line, and the valve stem would be moved up and down during the valve opening/closing, while the chuck connects with the wheel of the valve, enough space is needed for the shaft at the top of chuck. Therefore a hollow shaft that longer than the stem between the output shaft and the chuck need to be added, and due to the astaticism of the shaft, the actuator instability will be increased. Further research to eliminate the defects will be needed.