JPH0229327Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a ring-shaped valve that is interposed between the inner peripheral surface of the butterfly valve body and the outer peripheral edge of the disc-shaped valve body to close the valve. The present invention relates to a valve closing member, and particularly relates to a new structure of a ring-shaped valve closing member such as a seat ring or a back-up ring incorporating a metal coil spring.

(Prior art) Conventionally, a seat ring with a built-in metal coil spring and a ring-shaped valve closing member such as a back spring were attached to the inner circumference of the main body of a butterfly valve in parallel, and the valve closed by coming into contact with and separating from the valve body. A butterfly valve that opens and closes is well known and is disclosed, for example, in Japanese Patent Application Laid-open No. 124166/1983.

A ring-shaped valve closing member such as a seat ring or a back spring includes a metal coil spring that extends in a ring shape along the inner peripheral surface of the butterfly valve body, and one or two layers that cover the outer periphery of the coil spring. The seat ring is placed in contact with and separated from the outer periphery of the valve body, and the deformation of the seat ring is elastically reinforced with a back-up spring to achieve a reliable sealing effect. .

(Problems to be Solved by the Invention) A coil spring built into a conventional ring-shaped valve closing member such as a seat ring or a back-up spring is formed to have the same spring constant over its entire circumference. On the other hand, when the valve body is deformed due to fluid pressure, the valve blade direction (A ₇ section) is smaller than the valve stem direction (A ₁ section) in the valve stem direction and the valve blade direction (direction orthogonal to the valve stem direction). Since the amount of deformation is also large, the rotational tangential force of the valve shaft increases from the valve stem direction to the valve blade direction, and becomes maximum in the valve blade direction. As a result, as shown in Fig. 7, if the spring constant of the coil spring is constant over its entire circumference,
At _A7 , the valve closing torque (load) reached its maximum, causing problems in the valve closing operation.

(Means for solving the problem) This invention was made to solve the above-mentioned problem found in the ring-shaped valve closing member of the conventional butterfly valve. A ring-shaped valve closing member that is arranged and comes into contact with and separates from the valve body,
It is composed of a metal coil spring and a metal cylinder covering the outer periphery of the coil spring, and the spring constant of the coil spring is changed from the valve stem direction to the valve blade direction to adjust the amount of deformation of the valve body due to fluid pressure. It is characterized in that it is reduced in inverse proportion.

(Function) The spring constant of the coil spring constituting the ring-shaped valve closing member is gradually decreased in inverse proportion to the amount of deformation of the valve body from the direction of the valve stem to the direction of the valve blades. It is possible to reduce the rotational tangential force and make the closing torque of the valve the same over the entire circumference of the valve body.

(Effect of the invention) Since the valve closing torque is the same around the entire circumference of the valve body, even if the valve body is deformed by fluid pressure, there is no particular fluctuation in the valve closing torque, and it is always stable. This allows the valve to be closed.

(Embodiments) Preferred embodiments of this invention will be described below with reference to the drawings. In the figure, 1 is a main body of a butterfly valve formed in a substantially cylindrical shape, and 2 is a valve body formed in a disc shape, which is in contact with a ring-shaped valve closing member 3 disposed on the inner peripheral surface of the main body 1. The fluid is interrupted by separating it. Reference numeral 4 denotes a valve stem that rotatably supports the valve body 2, and at least one of the stems extends outside the main body 1 and is connected to a desired drive device.

The ring-shaped closing member 3 consists of a metal coil spring 5 and a metal cylinder 6 that covers the outer periphery of the coil spring, and has a ring-shaped structure extending along the inner peripheral surface of the main body 1. It continuously contacts the outer peripheral edge of the valve body 2 to achieve fluid closure. The ring-shaped closing member 3 generally includes a seat ring 30 shown in FIG. 2 and a back-up spring 31 shown in FIG. 3 as a set, and is assembled to the main body 1 as shown in FIG. Ru. The seat ring 30 directly approaches and separates from the outer peripheral edge of the valve body 2, and the back-up spring 31 backs up the seat ring 30 to prevent deformation of the seat ring 30 due to contact and separation from the valve body 30.

Note that the ring-shaped valve closing member 3 to which this invention is applied is not limited to the combination of the seat ring 30 and the back-up spring 31, and may be applied only to either the seat ring or the back-up spring. Of course, the seat ring or back-up ring to which the present invention is applied may be used in combination with a ring-shaped closing member of other structure.

In the ring-shaped valve closing member 3 of this invention, the spring constant of the coil spring 5 is not constant over the entire circumference of the ring like the conventional coil spring shown in FIG. 4, but as shown in FIG. By changing the pitch number of the coil spring 5, the number of turns in the valve stem direction is dense and the number of turns in the valve blade direction _is coarse.
The spring constant is made inversely proportional to the amount of deformation of the valve body 2 that increases due to fluid pressure in the valve blade direction _A7 .
As a result, as shown in FIG. 8, even if the amount of deformation of the valve body increases from the valve stem direction to the valve blade direction, the closing torque (load) of the valve can be kept constant.

The spring constant can be changed not only by changing the pitch but also by changing the wire diameter of the spring or by other methods.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the main parts of a butterfly valve to which this invention is applied, Fig. 2 is an enlarged sectional view of the seat ring, and Fig. 3 is an enlarged sectional view of the back spring.
Figure 4 is a side view of a conventional coil spring, Figure 5 is a side view of a conventional coil spring.
The figure is a side view of the coil spring of this invention.
The figure shows each measurement point of the valve body from the valve stem direction to the valve blade direction, and Figures 7 and 8 show the amount of deformation (strain) of the valve body and the closing torque (load ), FIG. 7 shows a conventional coil spring, and FIG. 8 shows a coil spring of this invention.

Claims (1)

[Scope of utility model registration request] A ring-shaped valve closing member disposed on the inner circumferential surface of the butterfly valve body and coming into contact with and separating from the valve body is composed of a metal coil spring and a metal cylindrical body covering the outer periphery of the coil spring. 1. A ring-shaped closing member for a butterfly valve, wherein the spring constant of the butterfly valve is reduced in inverse proportion to the amount of deformation of the valve body due to fluid pressure from the direction of the valve stem to the direction of the valve blades.