Low-torque pressure balance type cock valve

Abstract

A low-torque pressure balance type cock valve comprises a valve body, a valve cover, a valve rod and a cock. The cock is a hollow cylinder with a conical degree. The outer surface of the cock is matched with the inner surface of the valve body. The valve body is provided with a medium channel and the cock is provided with a medium channel corresponding to the medium channel of the valve body. The valve rod penetrates through the valve body and is connected with the cock. The valve rod can drive the cock to rotate relative to the valve body so that the valve can be opened or closed. Filler is arranged between the valve rod and the valve body and sealed through the valve cover. The valve rod is provided with an external thread. The valve body is provided with an internal thread and matched with the valve rod. The tail end of the valve rod is placed in a valve rod hole in the upper end of the cock and is of a flat tenon structure. Two limiting protrusions are arranged on the inner circle of the valve rod hole in a spaced mode. The limiting protrusions control the angular travel of the valve rod in the valve rod hole to be within the range from 0 to theta. When the cock valve is opened and closed, friction between matched surfaces is greatly reduced, the opening and closing torque is small, operation is convenient, and work is safe and reliable.

Description

Technical field [0001] The invention relates to a valve, in particular to a pressure balance plug valve. Background technique [0002] As the earliest valve used, the plug valve is widely used in the pipeline system with particles in the medium; the pressure balanced plug valve injects grease through the grease injection valve designed on the upper part of the upper cavity of the valve body, under the action of grease pressure A thin oil film layer is formed on the surface of the cock. When the grease injection pressure of the upper chamber is lower than the medium pressure, the check valve installed on the upper end of the cock can make the medium enter the upper chamber, so that the pressure of the upper and lower chambers is consistent and the cock is tight. Tightly press against the valve body to achieve two-way sealing; there are balance holes at the upper and lower ends of the cock, which are balanced under the combined action of medium, grease pressure and the cock's ...

AI Technical Summary

Problems solved by technology

[0003] Although the pressure balanced plug valve has the advantages of small operating torque compared with other plug valves, as the nominal diameter and pressure level increase, its operating torque changes in a parabola with the pound series. For example, for NPS12, Class2500 valves, Its maximum torque has reached 25000N m, which brings some inconvenience to the selection and operation of the driving device during design; in addition, when the upper cavity of the cock is not filled with grease on time or the balance hole of the cock is blocked, the opening torque often Multiplied, making the valve often difficult to open and close

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