JPH06213338A - Top entry type ball valve and method for its assembly - Google Patents

Abstract

PURPOSE:To provide a ball valve of top entry type which does not require any particularly high precision processing, is configured relatively simple, and can exert good sealing characteristic regardless of the flowing direction of the fluid. CONSTITUTION:A valve seat 16 is formed at the boundary between the incoming flow path 3 and outgoing flow path 4 of a ball accommodation chamber 2, and a seat packing 7 installed at the valve seat 16 is put in pressure contact with the side curved surface 6b of a ball 6. Besides this curved surface 6b consisting of a part of a spherical surface having a radius R, the ball 6 has an end part curved surface 6a which consists of a part of a spherical surface having a radius S smaller than R and is formed in point symmetry about a rotary shaft L, and also has a bottom part curved surface 6c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top entry type ball valve for opening and closing a valve by rotating a ball in a valve body by rotating a valve rod and a method for assembling the ball valve.

[0002]

2. Description of the Related Art Ball valves are attached to pipes, tanks, etc. and are widely used for controlling the fluid flowing therein.
This ball valve is a side entry type ball valve that divides the side of the valve body and mounts the ball from this divided part, and a top entry type ball valve that divides the valve body into upper and lower parts and mounts the ball from this upper part. Can be roughly divided into This latter top-entry ball valve is widely used, for example, for piping in nuclear power plants, because maintenance such as inspection and cleaning of the inside of the valve and replacement of seat packing can be performed without removing the piping.

FIG. 10 shows a top entry type ball valve described in Japanese Patent Publication No. 39-5583, in which a valve body 1 has a ball accommodating chamber 2 and flow holes 3 and 4 on the left and right sides. A ball 6 having a through hole 5 is rotatably housed in the ball housing chamber 2. The ball accommodating portion 2 and the ball 6 are tapered with respect to the center line of the valve rod, and a rubber or plastic seat packing 7 is interposed therebetween. A valve rod 9 penetrating the valve lid 8 is connected to the upper end of the ball 6,
To rotate. A spring 10 attached to the valve rod 9 urges the ball 6 downward to move the ball 6 into the seat packing 7
The ball 6 and the valve body 1 are sealed by being pressed against.

However, the top entry type ball valve having such a structure has a problem that the tapered portions of the ball accommodating chamber 2 and the ball 6 must be processed with high precision. Further, the urging force of the spring 10 that presses the ball 6 against the seat packing 7 requires a considerably large force, and it becomes difficult for the bearing 11 of the valve rod 9 that receives this reaction force to endure long-term use.

Further, since the seat packing 7 is constantly pressed downward by the spring 10, plastic deformation occurs and the ball 6 gradually descends to form a step between the through hole 6 and the through holes 3 and 4. Therefore, there is also a problem that the flow of fluid flowing through the ball valve becomes turbulent. Furthermore, this ball valve is essentially a floating type, and when the ball 6 is closed, the ball 6 is pushed to the downstream side by fluid pressure, and the ball 6 comes into close contact with the seat packing 7A on the downstream side to shut off the flow path. If the spring force is strong, this ball 6
Cannot be smoothly moved to the downstream side, and a smooth valve closing operation cannot be obtained.

Therefore, a top entry type ball valve which solves such a problem is disclosed in Japanese Utility Model Publication No. 58-11975. In this ball valve, a pair of taper rings 12 and 13 are interposed between the seat packing 7 and the valve body 1 without tapering the ball storage chamber 2 and the ball 6 as shown in FIG. At the same time, one taper ring 12 is pressed by the adjusting bolt 14. Therefore, the pressing force of the adjusting bolt 14 is applied to the seat packing 7 via the taper ring 12.
Acting in the flow path direction to maintain the adhesion between the seat packing 7 and the ball 6.

[0007]

However, the latter top-entry type ball valve of this latter type has a taper ring 12,
Complicated construction by adding 13 and taper ring 1
Due to the high processing accuracy of Nos. 2 and 13, there is a new problem that the cost is increased. Further, there is a problem that it cannot be used for piping in which fluid flows bidirectionally. That is, since this top entry type ball valve is also a floating type, when the fluid flows in the direction of the arrow in FIG. 11, the fluid is shut off when the valve is closed by the close contact between the seat packing 7A on the downstream side and the ball 6. Definitely done. However, when the fluid flows in the direction opposite to the arrow, the taper rings 12 and 13 cannot be completely sealed.

Therefore, the object of the present invention is to provide a top-entry type having a relatively simple structure and capable of exhibiting good sealing performance irrespective of the flow direction of the fluid without the need for highly precise processing. A ball valve and its assembling method are provided.

[0009]

In order to achieve this object, a top entry type ball valve according to the present invention comprises:
A valve body having a ball storage chamber and a pair of fluid passages perforated on both sides; a pair of valve seats formed between the ball storage chamber and the pair of flow holes; and a periphery of the flow hole. An annular seat packing disposed on the valve seat so as to surround the valve seat; and a side curved surface which is housed in the ball storage chamber rotatably around a rotation shaft and contacts the seat packing and the rotation shaft. A top-entry ball valve comprising: balls each having a through hole extending in a vertical direction; and a valve rod connected to an upper end portion of the ball to drive the ball to rotate about the rotation axis. In the ball, the distance between the upper end and the center of the ball and the distance between the lower end opposite to the upper end and the center of the ball are both set to be smaller than the distance between the side curved surface and the center of the ball. so That.

It is preferable that the regions of the upper end portion and the lower end portion are curved surfaces that are recessed from the surrounding curved surfaces by a predetermined amount.
The assembling method according to the present invention for assembling the top entry type ball valve having the above-mentioned configuration includes an installation step of installing the seat packing on the valve seat, and an upper end of the ball and a lower end opposite to the upper end of the pair of balls. A housing step of housing the ball in the ball housing chamber so as to face the through holes, and a rotating step of rotating the ball by about 90 ° to a position where the upper end can be connected to the valve rod after the housing step. And is equipped with.

In this assembling method, an engaging groove is formed around the through hole of the ball, and in the rotating step, a jig is engaged with the engaging groove so that about 90 of the ball is engaged. It is desirable to perform a rotation of °. Further, it is preferable that the installing step and the accommodating step are simultaneously performed by previously mounting the seat packing on the upper end portion and the lower end portion of the ball and then accommodating the ball in the ball accommodating chamber.

[0012]

In the ball, the distance between the upper end and the center of the ball and the distance between the lower end and the center of the ball are both smaller than the distance between the side curved surface and the center of the ball. Therefore, if the direction of the ball is determined so that the upper end portion and the lower end portion of the ball face the pair of flow holes of the valve body, the ball can be stored in the ball storage chamber easily and smoothly. The seat packing may be preliminarily installed on the valve seat before this accommodation, or may be attached to the upper end portion and the lower end portion of the ball during the accommodation. After that, when the ball is rotated about 90 ° to a position where the upper end of the ball can be connected to the valve rod, the side curved surface of the ball comes into pressure contact with the seat packing, and the ball is sealed with a sufficient sealing surface pressure.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ball valve according to the present invention will be described below with reference to FIGS. 1 to 9 in which the same parts as those in FIGS. In FIG. 1, the valve body 1 has a ball accommodating chamber 2 and flow holes 3 and 4 formed on both sides of the ball accommodating chamber 2. The ball 6 is housed in the ball housing chamber 2 so as to be rotatable around the rotation axis L. A valve hole 5 orthogonal to the rotation axis L is bored in the ball 6 so as to communicate with the inlet passage 3 and the outlet passage 4. A valve rod 9 is connected to the upper end portion 6a of the ball 6, and the valve rod 9 penetrates the valve lid 8 to rotate the ball 6 around the rotation axis L by operating the handle 15.
Valve seats 16 are formed at the boundaries between the ball accommodating chamber 2, the inlet flow path 3, and the outlet flow path 4, and an annular seat packing 7 is formed in each of these valve seats 16. Are installed to surround each. These sheet packing 7
Is pressed against the side curved surface 6 b of the ball 6 to seal the ball 6.

The ball 6 is a spherical curved surface with the side curved surface 6b having a radius of curvature R centered on the ball center O, and the upper end portion 6a and the lower end portion 6c are spherical curved surfaces recessed from the side curved surface 6b by a predetermined amount. Stipulated in. That is, the upper end 6a and the lower end 6c are set such that the distance S from the ball center O is smaller than the radius R by a predetermined amount.

2 and 3 show the relationship between the side curved surface 6b of the ball 6 and the upper end portion 6a and the lower end portion 6c. The diameter of the virtual curve C1 of the radius of curvature R of the side curved surface 6b is 2R. And the distance between the upper end 6a and the lower end 6c is 2S (2S <
2R). Further, the ball 6 is provided with a cutout groove 17 around the through hole 5.

Next, the operation of this embodiment will be described. The seat packing 7 and the balls 6 are installed in the valve body 1 as follows. The valve lid 8 is removed and an opening is formed in the upper portion of the valve body 1. Seat packings 7 are preliminarily attached to the upper end portion 6a and the lower end portion 6c of the ball 6, respectively. This ball 6
As shown in FIG. 4, the seat packing 7 has the valve seat 16
So that the upper end portion 6a and the lower end portion 6c of the ball face the inlet passage 3 and the outlet passage 4 of the valve body 1, respectively, and the through hole 5 of the ball 6 is in the plane orthogonal to the rotation axis L. Is inserted into the ball accommodating chamber 2 in a state where it is set in a direction deviated from the flow holes 3 and 4 by about 90 °. Since the distance 2S between the ball upper end 6a and the lower end 6b is much smaller than the diameter 2R of the side curved surface 6b, the upper end 6a of the ball 6
And the distance D between the seat packings 7 attached to the lower end 6c
1 is smaller than the distance D2 of the valve seat 16. Therefore, the ball 6 can be smoothly inserted into the ball storage chamber 2.

The mounting in the state of FIG. 4 can also be performed as follows. That is, the seat packing 7 is previously attached to the valve seat 1
6 and then the ball 6 is inserted between the seat packings 7 in the orientation described above. After this, the ball 6 is rotated 90 ° in the direction of the arrow in FIG. 4 so that the upper end portion 6a is located above and the lower end portion 6c is located below, as shown in FIG. 5, and the side curved surface 6b is brought into contact with the seat packing 7. . Since the distance R from the center O of the ball is considerably larger than the distance S between the upper end 6a or the lower end 6c and the ball, the side curved surface 6b is sufficiently pressed and brought into close contact with the seat packing 7.

The rotation of the ball 6 is performed by using the jig 18 shown in FIGS. 6 and 7. The jig 18 has teeth 19 that engage with the notches 17 in the balls 6 and
The ball 6 is rotated by rotating the handle 20 while the groove 9 is engaged with the cutout groove 17. After this, the valve lid 8 is attached and the valve rod 9 is connected to the ball upper end portion 6a.

8 and 9 show modifications of the above-described embodiment, respectively. In FIG. 8, the ball 6 has a chamfered upper end 6a and a lower end 6c. In FIG. 9, the ball 6 is notched in the upper and lower portions, and has a flat upper end portion 6.
a and a lower end portion 6c are formed.

The chamfered portion of FIG. 8 is also the flat upper end portion 6a of FIG.
Since the distance S between the ball center O and the lower end 6c is smaller than the radius of curvature R of the side curved surface 6b, the seat packing 7 is attached to the upper end 6a and the lower end 6c as in the above embodiment. Can be easily inserted into the ball storage chamber 2.

Of course, as in the embodiment of FIG.
By forming a and the lower end portion 6c on a curved surface, the rotation of 90 ° can be performed more smoothly than in the case of FIGS. 8 and 9.

In the present specification, the upper end portion and the lower end portion of the ball do not mean absolute top and bottom, but
The upper and lower sides in the direction along the rotation axis L of the ball are meant.

[0023]

As is apparent from the above description, according to the present invention, the shape of the ball is such that the distance between the upper end and the center of the ball and the distance between the lower end and the center of the ball are the same as the curved surface on the side of the ball The ball can be smoothly accommodated in the ball accommodating chamber and the ball can be sufficiently pressed against the seat packing with a very simple structure in which the distance is set to be smaller than the distance from the center of the ball. Further, the flow direction of the fluid is not limited, and it is possible to cope with the flow in any direction. Further, since the top entry type ball valve has an extremely simple structure, maintenance of the ball accommodating chamber becomes very easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a top entry type ball valve according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the ball of the above embodiment.

FIG. 3 is an enlarged front view of the ball of the above embodiment.

FIG. 4 is a cross-sectional view showing a method of installing balls in the ball storage chamber.

FIG. 5 is a cross-sectional view showing a method of installing balls in a ball storage chamber.

FIG. 6 is a front view showing a jig used in this embodiment.

FIG. 7 is a cross-sectional view showing a jig used in this example.

FIG. 8 is a front view showing a modified example of the above embodiment.

FIG. 9 is a front view showing a modified example of the above embodiment.

FIG. 10 is a sectional view showing a conventional top entry type ball valve.

FIG. 11 is a sectional view showing a conventional top entry type ball valve.

[Explanation of symbols]

 1 valve body 2 ball accommodating chamber 3, 4 through hole 5 through hole 6 ball 6a upper end, 6b side curved surface 6c lower end 7 seat packing 9 valve rod 16 valve seat L rotating shaft

Claims (5)

[Claims] 1. A valve body having a ball accommodating chamber and a pair of fluid passages formed on both sides thereof; a pair of valve seats formed between the ball accommodating chamber and the pair of flow holes; An annular seat packing disposed on the valve seat so as to surround the flow hole; a side curved surface that is housed in the ball storage chamber so as to be rotatable about a rotation axis and contacts the seat packing; A top entry including balls each having a through hole extending in a direction orthogonal to the rotation axis; and a valve rod connected to an upper end portion of the ball and rotationally driving the ball around the rotation axis. In a ball valve having a shape, the ball is formed by a side curved surface formed by a part of a spherical surface having a radius R and a part of a spherical surface having a radius S smaller than the radius R, and formed in point symmetry with respect to the rotation axis. Up Top entry type ball valve, characterized in that it has a part curved and the lower end surface. 2. The top entry type ball valve according to claim 1, wherein the upper end portion and the lower end portion are curved surfaces which are recessed from the curved surfaces around them by a predetermined amount. 3. A valve body having a ball accommodating chamber and a pair of fluid passages perforated on both sides; a pair of valve seats formed between the ball accommodating chamber and the pair of flow holes; An annular seat packing disposed on the valve seat so as to surround the flow hole; a side curved surface that is housed in the ball storage chamber so as to be rotatable about a rotation axis and contacts the seat packing; Top-entry type having a ball each having a through hole extending in a direction perpendicular to the rotation axis; and a valve rod connected to an upper end portion of the ball and drivingly rotating the ball around the rotation axis. In a method for assembling a top entry type ball valve for assembling a ball valve, an installation step of installing the seat packing on the valve seat, and an upper end portion of the ball and a lower end portion opposite to the upper end portion of the pair of flows. A storing step of storing the ball in the ball storing chamber so as to face the holes, and a rotating step of rotating the ball by about 90 ° to a position where the upper end can be connected to the valve rod after the storing step. And the distance between the upper end and the center of the ball and the distance between the lower end and the center of the ball are both smaller than the distance between the side curved surface and the center of the ball. A method of assembling a featured top entry type ball valve. 4. An engaging groove is formed around the through hole of the ball, and in the rotating step, a jig is engaged with the engaging groove to rotate the ball by about 90 °. The method for assembling a top entry type ball valve according to claim 3, wherein 5. The step of installing and the step of accommodating are performed at the same time by mounting the seat packing on the upper end and the lower end of the ball in advance and then accommodating the ball in the ball accommodating chamber. The method for assembling a top entry type ball valve according to claim 3.