JPH0374685A - Ball valve - Google Patents

Abstract

PURPOSE:To improve durability and to sharply reduce a cost by a method wherein two contact surfaces extended in the longitudinal direction of engaging pieces brought into contact with each other are formed in an arcuate shape in cross section swollen outwardly, and two contact surfaces extended in the longitudinal direction of an engaging groove form planes paralleling each other. CONSTITUTION:An engaging groove 22 is formed in the upper spherical surface of a spherical valve body 20, and an engaging piece 32 located to the lower end of stem 30 is inserted in the engaging groove. The engaging piece 32 forms a flat fan-shaped body extended at right angles with the axis of a stem 30, and two flat contact surfaces 33 and 33 form arcuate surfaces formed symmetrically about a center in an longitudinal direction. An engaging groove 22 forms a flat fan-shaped groove having contact surfaces 23 and 23 forming planes paralleling each other with a width therebetween being equal to or slightly wider than width between the two flat contact surfaces of the engaging piece 32. Even when the axis of a stem 30 is displaced from that of the spherical valve 20 due to an error, since the engaging piece 32 and the engaging groove 22 are brought into linear contact by means of a plane and an arcuate surface, they can be easily slid over each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a mechanism for rotating a spherical valve body of a ball valve.

[Prior Art] A ball valve includes a valve body with an inlet and an outlet, and a spherical valve body through which a flow passage passes through the center. The valve opens, and when communication is cut off, the valve closes. The spherical valve body is rotationally driven by a stem attached to the valve body, and the stem is rotated manually or automatically. The stem and the spherical body are connected to each other by inserting an engaging piece provided at the lower end of the stem into an engaging groove provided on the upper spherical surface of the spherical valve body. The engagement piece is a layered plate with two parallel faces, and the engagement groove is a fan-shaped groove with two parallel faces of the same width as the two parallel faces of the engagement piece, making plane contact with each other. Was.

[Problem to be Solved by the Invention] There is no problem if the stem 30 of the ball valve and the spherical valve body 20 are always coaxial, as shown by the solid line in FIG. If the axial center Al of the stem and the axial center A2 of the spherical valve body become misaligned due to a time error, not only will the 5 stems be twisted in the lateral direction, resulting in an even greater rotational friction, but also the spherical valve body 2o will swing around, causing the spherical valve Unreasonable force is also applied to the seat that supports the body, reducing the durability of the seat. Also, as shown by the solid line in Fig. 5, the stem 3o is
Even if the axes of the stem 3o and the spherical valve body 20 are coaxial, when the spherical valve body 20 is pushed in the flow direction by the fluid pressure p when the valve is closed, as shown by the chain line, the stem 3o and the spherical valve body 20 are Rotation axes AI and A2 are misaligned. If the stem 30 is rotated to open the valve in this state, the state shown by the chain line in FIG. 4 will occur, the stem will be twisted in the lateral direction, and the torque required to open and close the valve will increase significantly.

As described above, the conventional ball valve has a problem in that extra torque is required to open and close the valve due to the twisting of the stem 3o. Another problem with automatic valves is that when the required torque increases, the drive section becomes larger and the cost becomes significantly higher.

The present invention has been made in order to solve the above problems, and its main purpose is to prevent the torque for opening and closing the valve from becoming extremely large even if the rotational axes of the stem and the spherical valve body are misaligned, and the seat The object of the present invention is to provide a ball valve whose durability does not deteriorate.

[Means for Solving the Problems] In order to achieve the above object, the means adopted by the present invention is to attach the engagement piece at the lower end of the stem to the engagement groove on the upper spherical surface of the spherical valve body, so that the stem and the spherical valve body are connected to each other. In this type of ball valve, two contact surfaces extending in the longitudinal direction of the engaging pieces that contact each other are formed in an arc shape that bulges outward in cross section, and two contact surfaces extending in the longitudinal direction of the engaging groove are formed in a cross section. This is because they are formed on parallel planes.

[Operation] When the ball valve is assembled, even if the axis of the stem and the axis of the spherical valve body deviate due to an error, or the axis of the spherical valve body that was aligned with the axis of the stem when the valve was opened. Even if the retaining piece and the engaging groove are in line contact between a flat surface and an arcuate surface, even if the retaining piece and the engaging groove are displaced by fluid pressure when the valve is closed, they can easily slide against each other. Therefore, the stem is not forced laterally by the spherical valve body, the spherical valve body is not swung around by the stem, and the torque required to open and close the valve is the same as when the axes of the stem and the spherical valve body are aligned. Almost no change.

[Example] The ball valve of the present invention will be described based on an example shown in the drawings. As shown in FIGS. 1 and 2, the valve body 10 of the ball valve has a body portion 11 and a flange portion 12 connected together with bolts 13 and nuts 14, and the body portion 11 and the flange portion 12 are configured to have fluid flow. There will be an entrance and an exit. An engagement groove 22 is provided on the upper spherical surface of the spherical valve element 20, which is rotatably arranged between the inlet and the outlet inside the valve body 10 via a seat 15. An engaging piece 32 provided at the lower end of the stem 30 is inserted into the stem 30. The stem 30 is rotatably supported by the main body 11 via a bearing 34, and is rotated by a manual handle or an automatic drive device (not shown). Driven. The engagement piece 32 is a flat fan-shaped body extending orthogonally to the axis of the stem 30, and its two flat contact surfaces 33, 33 are formed into circular arc surfaces symmetrical about the center in the longitudinal direction. The engagement groove 22 is a flat fan-shaped groove having two parallel plane contact surfaces 23, 23 with a width equal to or slightly wider than the width between the two flat contact surfaces of the engagement piece 32.

When the engagement piece 32 is attached to the engagement groove 22, the two planar contact surfaces 23.23 and the two arcuate contact portions 33.33 come into linear contact with each other.

As shown in FIG. 3, the axial center A2 of the spherical valve body 20 is inclined with respect to the axial center A2 of the stem 30 due to an error during manufacturing and assembly. However, the two contact portions 23 of the engagement groove 22 are connected to the engagement piece 32.
The spherical valve body 2 is tilted as if rolling on the two contact parts 33 of
Since the axis A2 of 0 intersects the axis A1 of the stem 30 at the center of the engagement piece 32, the stem 30 will not be twisted laterally even if the spherical valve body 20 is tilted. 30, the planar contact surface 23 of the engagement lI22 can slide along the arcuate contact surface 33 of the engagement piece 32, so the spherical valve body 30 will not be swung around. The rotational resistance of the stem 30 is caused by the spherical valve body 20.
This is not as large as when the axis of the seat is not misaligned, and it can be said that there is less unreasonable force acting on the seat.

As shown in FIG. 5, when the valve is closed, the axis A2 of the spherical valve body 20 is displaced from the axis At of the stem 3o due to fluid pressure. If the stem 30 is then rotated, it will be in the same state as shown in FIG.
You will not be swayed by 0.

[Effects of the Invention] As described above, in the ball valve of the present invention, the engagement piece of the stem and the engagement groove of the spherical valve body have a slippery plane and an arcuate surface, unlike the conventional case where the engagement piece of the stem and the engagement groove of the spherical valve body are in plane contact with each other. Because of this line contact, even if the spherical valve body is misaligned with respect to the stem's axis due to manufacturing and assembly errors or fluid pressure, the stem will not be twisted laterally, and the spherical valve body will not be forced into position with respect to the stem's axis. Even if the stem is rotated while being deviated from the valve body, the spherical valve body rotates about its axis without being swung around. Therefore, even if there is a misalignment between the axes of the stem and the spherical valve body, there is no risk that the required rotational torque of the stem will increase significantly or that excessive force will be applied to the seat, reducing its durability. You can get the same effect.

In particular, in the case of automatic valves, conventionally a relatively large and expensive drive unit has been installed in consideration of the misalignment of the spherical valve body with respect to the axis of the stem, but with the present invention, the drive unit can be made smaller and cheaper. Since it can be changed, a special effect can be obtained in that the cost can be significantly reduced.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a ball valve according to an embodiment of the present invention, with FIG. 1 showing the state when the valve is open, and FIG. 2 showing the state when the valve is closed. Figure 3 is an exaggerated diagram showing the state in which the spherical valve body is displaced. Figure 4 is an exaggerated diagram showing the state in which the spherical valve body is displaced by fluid pressure. Figure 5 is a diagram in which the conventional stem is twisted. FIG. In the figure, the symbol lO is the valve body, 20 is the spherical valve body, 22
23 is an engagement groove, 23 is a contact surface, 30 is a stem, 32 is an engagement piece, and 33 is a contact surface. Figure 1

Claims (1)

[Claims] 1) A valve body (10), a spherical valve body (20) rotatably installed in the valve body, and a stem (30) bearing the valve body, and integrally attached to the lower end of the stem. In a ball valve in which the formed engagement piece (32) is placed in an engagement groove (22) provided on the upper spherical surface of the spherical valve body and the spherical valve body is rotated by the stem, the longitudinal direction of the engagement piece is The two contact surfaces (33) extending in the longitudinal direction of the engagement groove are formed in an arcuate shape with outwardly bulging cross sections, and the two contact surfaces (23) extending in the longitudinal direction of the engagement groove are formed in parallel planes. As a ball valve.