Soft and hard double seal fixed ball valve

Abstract

The invention discloses a soft and hard double-seal fixed ball valve, which comprises a valve body, a valve seat and a spherical valve core. It is made of metal, and the valve seat has a hard sealing surface. The hard sealing surface is the surface of the valve seat in contact with the spherical valve core. The shape of the hard sealing surface is consistent with the arc surface of the corresponding spherical valve core. The hard sealing surface is the same as the spherical valve core. The contact of the core constitutes the primary hard seal, and the first O-ring of rubber material is fixed on the valve seat, and the contact between the first O-ring and the spherical valve core forms the secondary soft seal. The hard double seal combination sealing structure makes the sealing performance of the ball valve more reliable and basically meets the "zero leakage" sealing requirement. The outer surface of the first O-ring made of rubber has a polytetrafluoroethylene layer, which not only ensures the elasticity and toughness of the sealing surface, It also reduces friction, improves wear resistance, and increases the opening and closing times of the ball valve to more than ten times.

Description

technical field [0001] The invention relates to a ball valve structure, in particular to a fixed ball valve with an improved sealing structure. Background technique [0002] The ball valve mainly uses a sphere with a hole to rotate 90° under the control of the valve stem to open or close the valve. Since the channel diameter is equal to or smaller than the inner diameter of the pipe, the fluid resistance is small, the switch is fast and convenient, and the service life is long and reliable. High performance, has been widely used. [0003] The sealing forms of existing ball valves are roughly divided into two types: soft seal and hard seal. [0004] The characteristics of soft-sealed ball valves are: under the action of pretightening force or fluid pressure, the valve seat material is mostly special plastic, such as PEEK (polyether ether ketone), PTFE (polytetrafluorohexene), nylon, etc. It is made of more rigid plastic material to meet the temperature and pressure performa...

AI Technical Summary

Problems solved by technology

The advantages of using metal-to-metal sealing pairs for valve seat materials are: the applicable temperature range is wide, and the thermal expansion coefficients of various metal materials are not much different. High, the specific pressure to achieve sealing is also high. In the case of low pressure, it is difficult to achieve the sealing effect by fluid pressure. Even if the pre-tightening force is used to achieve sealing, the opening and closing torque of the ball valve will decrease The larger the sealing pair is, the faster the wear of the sealing pair is, and the service life of the valve is not high

Due to the increase of switching torque, it is more difficult to rely on manual operation, so hard-sealed ball valves generally use gear boxes, electric or pneumatic valve actuators to drive the opening and closing of the valve, and some valve driving devices will be more expensive than the valve. Many, not all applications require this equipment, and sometimes adding these devices is a last resort

[0006] In addition, ball valves have not been very satisfactorily adjustable to date, so when the seat starts to leak due to excessive wear, the valve must be replaced or repaired

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