Low flow resistance axial flow check valve with slow closing protection function at the end of closing

Abstract

The invention discloses a low flow resistance axial-flow type check valve with the closing tail section with a slow closing protection function. The low flow resistance axial-flow type check valve is characterized in that tail cone flow guide set holes are formed in a tail cone to be communicated with a tail cone cavity, a tail cone throttling opening is formed in the front end of the tail cone, a damping flap is installed at the tail end of a valve rod, the outer diameter of the damping flap is identical with the aperture of the tail cone throttling opening, and a throttling conical surface is arranged on the periphery of the front side of the damping flap; the crown part of a valve clack is provided with a cylindrical valve clack cylinder in a backward mode, and the outer circle of the valve clack cylinder is matched with a guide hole of an inner container of a valve body; a flow passing hole is formed between the tail cone cavity and the internal cavity of the valve clack and the inner container of the valve body; a front guide sleeve and a rear guide sleeve are arranged in the valve to support and guide the valve rod, and a valve flow channel is of a streamline structure. The low flow resistance axial-flow type check valve with the closing tail section with the slow closing protection function has the advantages that effective slow closing protection can be provided at the closing tail section of the valve, and a slow closing protection mechanism is reliable in work, simple in structure and low in production cost; exposed pipelines do not exist, damage is not likely to be generated, the hidden danger of external leakage does not exist, the working temperature of the valve is not limited, and the valve has lower pressure losses and the higher circulation capability.

Description

technical field [0001] The invention relates to a valve structure, in particular to a structure of an axial flow check valve. Background technique [0002] In petrochemical, natural gas, chemical industry, electric power, urban water supply and drainage and other industries, in order to prevent fluid backflow, motor and pump reversal caused by power outages or equipment failures in systems and pipelines conveying fluids, thereby affecting the safe operation of pipelines and equipment or even It will cause serious damage to the pipeline network and equipment, and a check valve needs to be installed on the outlet of the pump or on the pipeline. For all kinds of check valves, especially large-diameter check valves, if there is no slow-closing protection structure in the design of the valve structure, when the medium flows back due to reasons such as stopping the pump, the huge thrust of the reverse-flowing medium will And under the action of the spring force of the spring set ...

AI Technical Summary

Problems solved by technology

The disadvantages of this structure are: (1) The effect of slow closing protection is poor, and the role of the weight is more reflected in maintaining the auxiliary valve clack at the fully open position when the valve is opened, eliminating the oscillation and drift of the valve clack, and Reduce and eliminate the wear of the rotating shaft and the impact noise of the valve disc and the valve body; (2), the reverse torque of the weight is added to the whole process of valve disc closing, which is not conducive to the safety protection of the pump and the system; (3), the rotating shaft wears The part of the valve body is generally equipped with a packing compression structure, and the large packing friction will hinder the movement of the rotating shaft and the valve disc, affecting the reliability of the valve.

The disadvantages of this kind of slow-closing structure are: (1), the structure is more complicated, and the manufacturing cost is high; (2), when the backflow pressure is large or turbulent flow occurs, the movement of the cylinder piston is accelerated, resulting in insignificant cushioning effect; (3), The oil pressure pipeline is exposed, easy to be damaged, and it is inconvenient to refuel; (4), the seal used in the oil cylinder is a rubber part, so the working temperature of the valve is limited, and it can only be used in normal temperature conditions; (5) . When the oil cylinder sets the damping for the whole process of the valve clack, the closing speed of the valve clack is slow, which affects the protection of the valve to the pump and the system; (6). When the valve is closed, the valve disc quickly approaches the end of the piston rod of the cylinder, which will produce strong impact and collision sound; and the contact surface between the end of the piston rod and the valve disc may be damaged due to strong collision, which may hinder the contact surface that must exist in the closing process. Slippage, which will cause the piston rod to jam and make it difficult for the disc to reach the fully closed position

3. Set the built-in slow-closing piston cylinder and use the working medium in the valve as the working medium of the piston cylinder, such as image 3 , Figure 4 As shown, its disadvantages are: (1) When the medium contains impurities, the impurities may cause the piston to jam or cause the surface of the piston or cylinder to be strained, which will affect the reliability of the buffer mechanism; (2) 1. It is easy for impurities to block the bypass pipe. After the bypass pipe is blocked, the buffer mechanism will not be able to function; (3). If the liquid that is easy to freeze is transported in the pipeline, such as the working medium The medium in the through pipe freezes due to low temperature and no flow, which will also cause the buffer mechanism to lose its effect

For the axial flow check valve, especially the axial flow check valve with a larger diameter, it is also necessary to set up a slow closing protection structure to reduce or eliminate the impact and water hammer when the disc is closed; The structural characteristics of the return valve are different from other types of check valves. The valve stem is located in the closed or semi-closed space in the middle of the valve, which brings difficulties to the setting of the slow closing protection structure. Therefore, the current axial flow check valve For the time being, there is still a lack of products with practical value equipped with slow-closing protective structures that can be used for model selection and matching in relevant operating conditions

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