The spring-loaded quick-closing butterfly valve consists of several key components: a valve body, a butterfly disc, a spring mechanism, and an actuator. The valve body houses the butterfly disc, which is mounted on a shaft that allows it to rotate. The spring mechanism is designed to automatically close the valve quickly when the actuator is released or when there is a loss of power. This design ensures rapid sealing of the valve, preventing backflow and maintaining system pressure. The actuator can be manual or automatic, providing flexibility in operation.
The spring-type quick-closing butterfly valve mainly consists of the butterfly valve, hydraulic-spring drive device, hydraulic station, and electric control box. When opening the valve, the system sends a command (the electric control box is set to remote control), the hydraulic station operates, hydraulic oil enters the bottom of the oil cylinder to push the piston, which drives the butterfly valve to open, while the spring in the spring cylinder is compressed to store energy. In case of an emergency in the working system, the butterfly valve will receive an accident signal and quickly close under the action of the spring, with a closing time of 0.13 to 0.15 seconds, thus protecting the working system and pipeline equipment.
Since the working medium of the quick-closing butterfly valve is medium to high-temperature gas, a special structure was adopted in the design of the butterfly valve.
(1) Butterfly Plate: The butterfly plate adopts a three-eccentric structure, allowing the sealing surface of the butterfly plate to immediately disengage from the valve body sealing surface at the moment of opening, and only at the moment of closing does the sealing surface of the butterfly plate contact and press against the valve body sealing surface to ensure sealing, completely eliminating wear and scratches between the two sealing surfaces. The conical structure also has a self-centering function, ensuring the butterfly plate is properly aligned.
(2) Floating Sealing Ring: The metal-graphite sandwich sealing ring of the butterfly plate adopts a floating sealing form. When temperature changes occur during the installation or use of the butterfly valve, the floating sealing ring can compensate for the slight deformation of the valve body, keeping the sealing of the butterfly valve in optimal condition.
(3) Shaft End Temperature Compensation Mechanism: Due to the high operating temperature of the butterfly valve, and considering the thermal expansion effect of the valve shaft, temperature compensation mechanisms are added at both the upper and lower shaft ends to prevent the valve shaft from being pressed against, which would prevent the valve from opening normally. Several groups of support spacers, which function similarly to disc springs, automatically adjust for the dimensional changes of the valve shaft caused by temperature, compensating for adverse factors caused by excess deformation, thus ensuring that the butterfly plate does not deviate, the shaft end does not leak, and the tail end does not get damaged.
The normal working state of the quick-closing butterfly valve (powered state) is normally open, and it only requires a quick close when a fault occurs in the system (power-off state). Based on this characteristic, the drive device must have an automatic reset function, meaning that when powered, the drive device opens the butterfly valve, and when power is off, the drive device automatically resets to close the butterfly valve. There are many types of automatic reset drive devices, and considering the high safety performance requirements of the butterfly valve, a structure using a fork drive and spring reset is adopted, which mainly consists of a housing, fork, oil cylinder, piston, piston rod, spring, and spring cylinder.
Since the quick-closing time of the butterfly valve is required to be within 0.15 seconds, and considering performance, the pins in the fork are made of alloy steel, and cylindrical roller bearings are assembled at the contact part of the fork, transmitting the piston force of the oil cylinder to the fork in a rolling manner. This reduces friction, increases lifespan, and improves torque transmission efficiency. Due to the use of a spring action mechanism, careful consideration has been given to the safety of the spring, with an independent safety protection screw, allowing for the installation and disassembly of the spring on-site without special tools, ensuring the safety of the operator. This makes the loading and unloading of the spring both safe and convenient.