JP3815669B2 - Ball valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball valve, and more particularly to a technique that is effective when applied to an improvement in sealing performance when the ball valve is used at a high temperature.
[0002]
[Prior art]
Today, various pipes such as plant pipes are widespread, and various valves are used to control the fluid in these pipes.
[0003]
Here, as a valve that exponentially controls the flow rate of the fluid flowing through the pipe, there is a ball valve including a ball having a V-shaped through hole.
[0004]
A conventional ball valve including a ball having a V-shaped through hole will be described.
[0005]
In this ball valve, the ball formed with the V-shaped through hole is rotatably disposed on a flow path formed in the housing, and the ball is rotated to communicate the through hole with the flow path. The channel is opened and closed by blocking or blocking. An annular ball sheet is provided in contact with the outer peripheral surface of the ball, and this ball sheet is held by a seat retainer. The seat retainer is urged toward the ball by a spring and is disposed so as to be displaceable in the axial direction of the flow path.
[0006]
In such a ball, since the ball-shaped through-hole is deformed so that the ball sheet is lifted from the seat retainer due to the phenomenon that the V-shaped through hole scrapes the ball sheet from the through-hole by the rotation of the ball. The valve operating torque is increased as compared with a ball having a hole. Then, the actuator for rotating the ball becomes large, and the product cost increases.
[0007]
Further, due to the deformation of the ball seat, the fluid leaks from the deformed portion, and the sealing performance of the ball valve is greatly deteriorated.
[0008]
Further, due to the deformation of the ball seat, the ball seat may be misaligned or unevenly worn, and the sealing performance of the ball valve cannot be stably maintained.
[0009]
When the ball sheet is softened by a high-temperature fluid such as steam, the amount of deformation of the ball sheet is increased, which is a further problem.
[0010]
In order to prevent such deformation of the ball sheet, it is conceivable to fix the ball sheet to the seat retainer with an adhesive. For example, when the fluid used is steam, the adhesive is easily used. I can't do it.
[0011]
In order to solve such problems, Japanese Patent Application Laid-Open No. 9-210224 discloses a trunnion-type steam ball valve that presses and holds the ball seat by bending the tip of the seat holder inward and caulking. Technology is disclosed.
[0012]
[Problems to be solved by the invention]
However, according to this technique, the ball seat may be distorted by caulking, and a stable sealing property cannot be obtained.
[0013]
Further, since the ball sheet is fixed to the sheet holder, only a certain portion of the ball sheet rubs against the through-hole of the ball, and uneven wear of the ball sheet still occurs.
[0014]
Furthermore, a press machine for caulking is required, resulting in an increase in the manufacturing unit price.
[0015]
In the caulking method, when the ball sheet needs to be replaced, only the ball sheet cannot be removed, and the entire sheet holder must be replaced. Therefore, the replacement cost is high.
[0016]
Therefore, an object of the present invention is to provide a ball valve that can obtain a stable sealing performance by a ball seat.
[0017]
Another object of the present invention is to provide a ball valve that can prevent uneven wear of a ball seat.
[0018]
[Means for Solving the Problems]
In order to solve the above problems, a ball valve according to the present invention is rotatably supported by a stem on a flow path formed in a housing, and has a through-hole communicating with the flow path. A ball that is rotated by the operation of the stem in a direction to open and close the flow path by a hole, an annular ball seat provided in contact with the ball, and an axial displacement of the flow path in the flow path provided, said annular seat holding portion for holding the ball seat in a state in which a gap is provided between the outer periphery of the ball seat is provided on the opposite side of the ball of the sheet holding portion, the sheet holding portion the and a said ball-side sheet spring pressing to be pressed against the ball seat in the ball, the ball seat, the body cavitation surrounded by the housing and the ball And in a state where between the seal and the flow path, characterized in that it rotates in the circumferential direction with the rotation of the ball independently of the sheet holding unit.
[0019]
According to such an invention, since the ball seat is held in the sheet holding portion by being pressed against the ball by the force of the seat spring with the outer periphery having a gap with the sheet holding portion, the ball seat is distorted. There is no fear of this, and a stable sealing property can be obtained.
[0020]
Prevention Further, the rotation of the ball, since the ball seat is rotated independently in the circumferential direction and the sheet holding section, the contact position of the ball of the ball seat is varied locally deformed or uneven wear of the ball seat Is done.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. Here, in the accompanying drawings, the same reference numerals are given to the same members, and duplicate descriptions are omitted. The embodiment of the invention is a particularly useful embodiment in which the present invention is implemented, and the present invention is not limited to the embodiment.
[0022]
1 is a cross-sectional view showing a ball valve according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a main part of the ball valve of FIG. 1, and FIG. 3 is a ball fitted into a seat retainer in the ball valve of FIG. FIG. 4 is an explanatory view showing the movement of the ball seat when the ball is rotated in the ball valve of FIG. 1, and FIG. 5 is a schematic view of a ball valve according to another embodiment of the present invention. FIG. 6 is a cross-sectional view showing the main part of a ball valve according to still another embodiment of the present invention, and FIG. 7 shows the main part of a ball valve according to still another embodiment of the present invention. FIG. 8 is a cross-sectional view showing the main part of a ball valve according to still another embodiment of the present invention.
[0023]
In the ball valve of the present embodiment shown in FIGS. 1 and 2, the housing 10 is composed of a body 10a and a bonnet 10b, and has a top entry type structure in which a cylindrical flow path 11 is formed. ing. However, other structures such as a side entry type may be used.
[0024]
Inside the housing 10, a ball 12 having a V-shaped through hole 12 a (see FIG. 4) communicating with the flow path 11 is disposed on the flow path 11. The ball 12 is disposed in a direction orthogonal to the flow path 11 and supported by a pair of stems 13a and 13b rotated by an electric actuator (not shown). The flow path is formed through the through-hole 12a with the stems 13a and 13b as rotation fulcrums. 11 is mounted so as to be rotatable in the direction of opening and closing. The fluid flow rate is exponentially controlled by the V-shaped through hole 12a.
[0025]
Here, the ball 12 is made of metal, resin, or ceramic. In the case of metal, for example, stainless steel, carbon steel, ductile, cast iron, bronze, brass, stellite, etc. For example, fluororesin or nylon resin is used.
[0026]
A body cavity 14 that is a space partially surrounded by the housing 10 and the balls 12 is formed around the stems 13a and 13b. The stem 13a and the bonnet 10b are sealed with an O-ring 15.
[0027]
As shown in detail in FIG. 2, in order to seal between the flow path 11 and the body cavity 14 and prevent fluid from leaking out of the flow path 11, an annular ball sheet 16 is formed on the outer peripheral surface of the ball 12. It is provided in contact. Accordingly, the ball 12 rotates while sliding with the ball sheet 16. The ball sheet 16 is made of a resin material such as a fluororesin or a rubber material such as a synthetic rubber, but may be made of metal. Further, in the present embodiment, the ball sheet 16 is provided only on one side of the ball 12, but may be provided on both sides.
[0028]
The ball seat 16 is held by an annular seat retainer (sheet holding portion) 17. The seat retainer 17 is provided so as to be displaceable in the axial direction of the flow path 11, and an insert 18 is disposed on the opposite side of the seat retainer 17 from the ball 12. A seat spring 19 is fitted between the seat retainer 17 and the insert 18, and the ball seat 16 is pressed against the ball 12 with a substantially constant force by the seat spring 19 through the seat retainer 17.
[0029]
The seat retainer 17 and the body 10a, the insert 18 and the body 10a, and the seat retainer 17 and the insert 18 are sealed by O-rings 20, 21, and 22.
[0030]
Here, the ball seat 16 is rotatably held by the seat retainer 17. That is, as shown in FIG. 2, the ball sheet 16 is formed with a protruding portion (first locking portion) 16 a in the circumferential direction of the outer periphery. Further, the seat retainer 17 is formed with a groove portion (second locking portion) 17a that fits with the protruding portion 16a in the circumferential direction of the inner periphery . Then, the groove 17a is fitted with the protrusion 16a in a state where a clearance is secured between the outer periphery of the ball seat 16 and the seat retainer 17, so that the ball seat 16 is circumferentially independent of the seat retainer 17. The sheet retainer 17 is rotatably held.
[0031]
Note that the protrusion 16a and the groove 17a are not necessarily provided on the entire circumference. For example, when the protrusion 16a of the ball seat 16 is partially provided, the groove 17a of the seat retainer 17 is formed over the entire circumference. .
[0032]
Further, the outer periphery of the ball sheet 16 is formed at the front end in the insertion direction of the ball sheet 16 and has an introduction portion 23a having a smaller tip diameter than the inner diameter of the opening of the seat retainer 17, and the introduction portion 23a and the projection portion 16a. And an insertion guide portion 23 formed of a taper portion 23b having a diameter gradually larger than the inner diameter at the front end of the opening of the seat retainer 17 from the introduction portion 23a toward the projection portion 16a. Consideration can be given that the ball seat 16 can be smoothly fitted into the seat retainer 17.
[0033]
That is, when the ball seat 16 is fitted into the seat retainer 17, the introduction portion 23 a is first adjusted to the inner diameter of the seat retainer 17 as shown in FIG. When the ball seat 16 is inserted into the seat retainer 17 from such a state, the ball seat 16 is guided to the tapered portion 23b as shown in FIG. The diameter of the projecting portion 16 a is reduced smoothly by being pressed by 17, and the ball seat 16 enters the seat retainer 17 smoothly. When the ball sheet 16 is further inserted, as shown in FIG. 3C, when the protrusion 16a is released from the pressing and compressing diameter by the seat retainer 17 and expanded to the original size, the protrusion 16a of the ball sheet 16 and The ball seat 16 is completely mounted and held on the seat retainer 17 by fitting with the groove 17a of the seat retainer 17 with a gap .
[0034]
In this way, the elasticity of the ball sheet 16 (the elasticity caused by the material if the ball sheet 16 is made of resin, the elasticity caused by the shape if the ball sheet 16 is made of metal or ceramic) is used. As the protrusion 16a of the ball seat 16 expands and contracts, the ball seat 16 is mounted and held on the seat retainer 17 with one touch.
[0035]
Here, when the ball sheet 16 is made of metal or ceramic, for example, as shown in FIG. 8, the radial cross section is substantially J-shaped, and the locking portion 16 d (first) is elastically deformable in the radial direction. ).
[0036]
The width of the introduction portion 23a is suitably 60% or less of the thickness of the ball sheet 16. Further, the insertion angle θ of the tapered portion 23b is suitably 20 to 40 °, and preferably 30 °.
[0037]
Here, the gap is not at the tip of the ball seat 16 in the insertion direction , but is secured on the outer periphery of the ball seat 16, particularly around the engaging portion with the seat retainer 17.
[0038]
Between the ball seat 16 and the seat retainer 17, a gap larger than the thermal expansion allowance of the ball seat 16 is formed. Due to such a gap, the ball seat 16 is not pressed against the seat retainer 17 even if it is thermally expanded. Therefore, even if the ball valve is applied not only to the normal temperature fluid but also to the high temperature fluid, the ball seat 16 does not adhere to the seat retainer 17. It is held rotatably and distortion is prevented from occurring.
[0039]
Further, the ball seat 16 is held by the seat retainer 17 so that the surface 16 c opposite to the insertion side is flush with the front end surface 17 c of the seat retainer 17 . Therefore, since the ball seat 16 and the seat retainer 17 are flush with each other when the ball seat 16 is correctly inserted, the mounting reliability can be ensured only by checking whether they are flush with each other.
[0040]
Here, the outer diameter of the protrusion 16 a can be about 110 to 160% of the diameter of the ball sheet 16. Alternatively, the protrusion dimension of the protrusion 16a in the case of the ball sheet 16 up to the nominal diameter 125A is 0.2 to 3 mm, and the protrusion dimension of the protrusion 16a in the case of the ball sheet 16 exceeding the nominal diameter 125A is 0.8 to 6 mm. can do. In the case of the ball sheet 16 having a nominal diameter of 15A in the present embodiment, the protruding dimension of the protrusion 16a is 0.3 mm, and is dimensioned to be locked to the seat retainer 17 in consideration of the aforementioned gap. .
[0041]
In the ball valve having such a structure, the ball 12 is rotated by a predetermined amount by the stems 13a and 13b to connect the through hole 12a with the flow path 11 to open the flow path 11, and a desired amount of fluid passes through the pipe. Control to flow.
[0042]
At this time, since the pressing force between the ball seat 16 and the seat retainer 17 is automatically adjusted by the seat spring 19, the contact surface between the ball seat 16 and the seat retainer 17 can be used without using a sealing member such as a liquid gasket. Sealing performance is ensured.
[0043]
In addition, the sealing property may be further improved by making the contact surface of the ball sheet 16 tapered or providing irregularities on the contact surface.
[0044]
Here, the present inventor conducted a comparative test between the ball valve of the present application and a conventional ball valve.
[0045]
Saturated steam having an absolute pressure of 1 MPa and a saturation temperature of 180 ° C. was used as the working fluid. In any ball valve, the material of the seat retainer is CAC406 (JIS), the material of the ball seat is a fluororesin member such as PTFE containing carbon fiber or graphite, and the ball is a ball having a V-shaped through-hole. did.
[0046]
The valve operation torque after 2,000 durability tests was 4 N · m at normal temperature and 12.16 N · m at saturation temperature in the conventional ball valve. This is considered to be because the ball seat was deformed by the above-described scraping phenomenon and the valve operation torque gradually increased.
[0047]
On the other hand, the valve operating torque of the ball valve of the present application was 3.4 N · m at room temperature and 3.4 N · m at the saturation temperature. This means that the valve operating torque is reduced by about 15% at room temperature and about 72% at the saturation temperature compared to the conventional ball valve.
[0048]
Thus, according to this embodiment, is pressed against the ball 12 is held on the sheet retainer 17 by the force of the sheet spring 19 fiberboard sheet 16 with its outer periphery with a gap and sheet holding retainer 17 Therefore, there is no possibility that the ball seat 16 is distorted unlike when the seat retainer 17 is caulked, and a stable sealing property is obtained.
[0049]
Further, as shown in FIG. 4, the rotation of the ball 12, since the ball seat 16 is rotated in a circumferential direction independently of the sheet retainer 17, the ball seat contact position of the ball of the ball seat 16 is varied 16 local deformation and partial wear are prevented, and a stable sealing property can be obtained.
[0050]
Further, since the ball seat 16 is fitted and held in the seat retainer 17, the ball seat 16 is prevented from being lifted when the ball 12 is rotated, that is, the contact surface pressure between the ball seat 16 and the ball is increased. An increase in valve operation torque is suppressed.
[0051]
Furthermore, since the ball seat 16 is held by the seat retainer 17 simply by fitting the ball seat 16 into the seat retainer 17, the ball seat 16 can be easily assembled.
[0052]
Since the ball valve can be assembled while the ball retainer 17 is held by the seat retainer 17, no special consideration is required to prevent the ball seat 16 from being detached from the seat retainer 17, and the assembly work is facilitated. It becomes possible.
[0053]
Then, when the ball seat 16 is caulked to the seat retainer 17, it becomes difficult to remove the ball seat 16, but according to the present application, the ball seat 16 can be easily attached by releasing the fitting between the ball seat 16 and the seat retainer 17. Since the seat retainer 17 can be removed, it is possible to replace only the ball seat 16 during maintenance of the ball valve.
[0054]
Note that the width of the groove 17a formed in the seat retainer 17 may be formed substantially equal to the width of the protrusion 16a of the ball sheet 16, as shown in FIG.
[0055]
In this case, a step portion is formed in the inner peripheral back portion of the seat retainer 17 , and the lifting of the ball seat 16 can be suppressed by this step portion.
[0056]
Further, in the above description, although the opposite surfaces 16c and the insertion side of the ball seat 16 is adapted to be retained on the sheet retainer 17 is the leading end face 17c and the same surface of the sheet retainer 17, shown in FIG. 6 As described above, even if the ball seat 16 is held by the seat retainer 17 in a state where the surface opposite to the insertion side of the ball seat 16 is located on the inner side of the front end surface of the seat retainer 17 , or conversely, The surface that is opposite to the insertion side may be held by the seat retainer 17 in a state where the surface opposite to the front end surface of the seat retainer 17 is located.
[0057]
Further, as shown in FIG. 7, the groove 16 b may be formed as a first locking portion in the ball sheet 16, and the protrusion 17 b may be formed as a second locking portion in the seat retainer 17.
[0058]
Further, in the present embodiment, the seat retainer 17 serves as a seat holding portion for holding the ball seat 16, but various members such as a cap may be used depending on the structure of the body 10 a, the bonnet 10 b, or the ball valve. It becomes a sheet | seat holding | maintenance part which hold | maintains.
[0059]
The present invention can be applied to various types of ball valves such as a floating type as well as a trunnion type.
[0060]
In the ball valve according to the present embodiment, the shape of the through-hole 12a formed in the ball 12 is V-shaped. For example, the ball valve includes a ball having a through-hole having a shape other than the V-shape such as a circle. It can also be applied.
[0061]
【The invention's effect】
As is apparent from the above description, the present invention can provide the following effects.
[0062]
(1) Since the ball seat is pressed against the ball with its outer periphery having a gap and is held by the sheet holding portion, there is a risk that the ball seat may be distorted as if it is crimped to the sheet holding portion. Therefore, a stable sealing property can be obtained.
[0063]
(2). By the rotation of the ball, since the ball seat is rotated independently in the circumferential direction of the sheet holding unit, local deformation and uneven wear of the ball seat contact position fluctuates with the ball of the ball seat Is prevented, and a stable sealing property can be obtained.
[0064]
(3) Since the ball seat is fitted and held in the seat holding portion, the ball seat is prevented from being lifted when the ball is rotated, and the contact surface pressure between the ball seat and the ball is increased, that is, the valve is operated. The increase in torque is suppressed.
[0065]
(4) Since the ball sheet is held by the sheet holding part simply by fitting the ball sheet into the sheet holding part, it is possible to easily incorporate the ball sheet without performing labor-intensive work such as caulking or bolting. become.
[0066]
(5) Since the ball valve can be assembled while the ball seat is held in the seat holder, no special consideration is required to prevent the ball seat from coming off the seat holder, making assembly work easier. It becomes possible to do.
[0067]
(6). When the ball sheet is crimped to the seat holding part, it becomes difficult to remove the ball sheet, but according to the present application, the ball sheet can be easily held by releasing the fitting between the ball sheet and the sheet holding part. Therefore, it is possible to replace only the ball seat during maintenance of the ball valve.
[0068]
(7) If the insertion guide portion is formed on the ball seat, the ball seat can be smoothly fitted into the seat holding portion.
[0069]
(8) If a gap more than the thermal expansion allowance of the ball seat is formed between the ball seat and the seat holding portion, the ball seat will not be pressed against the seat holding portion even if thermally expanded. Is applied not only to a normal temperature fluid but also to a high temperature fluid, the ball sheet is rotatably held by the sheet holding portion, and distortion is prevented from occurring.
[0070]
(9) Further, if the surface opposite to the ball seat insertion side is flush with the front end surface of the sheet holding part and is held by the sheet holding part, check whether they are the same surface. By doing so, the mounting reliability can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a ball valve according to an embodiment of the present invention.
2 is a cross-sectional view showing a main part of the ball valve of FIG. 1;
3 is a cross-sectional view continuously showing a ball seat fitted in a seat retainer in the ball valve of FIG. 1. FIG.
4 is an explanatory view showing the movement of the ball seat when the ball is rotated in the ball valve of FIG. 1. FIG.
FIG. 5 is a cross-sectional view showing a main part of a ball valve according to another embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a main part of a ball valve according to still another embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a main part of a ball valve according to still another embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a main part of a ball valve according to still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Housing 10a Body 10b Bonnet 11 Flow path 12 Ball 12a Through-hole 13a, 13b Stem 14 Body cavity 15 O-ring 16 Ball seat 16a Protrusion part (1st latching | locking part)
16b Groove (first locking part)
16c Opposite surface 16d Locking portion (first locking portion)
17 Sheet retainer (sheet holding part)
17a Groove (second locking part)
17b Projection (second locking part)
17c End face 18 Insert 19 Seat spring 20, 21, 22 O-ring 23 Insertion guide part 23a Introduction part 23b Taper part θ Insertion angle

Claims (7)

A through hole communicating with the flow path is formed on the flow path formed in the housing and supported by the stem, and the stem is operated in the direction to open and close the flow path by the through hole. A rotating ball,
An annular ball seat provided in contact with the ball;
An annular sheet holding portion that is provided in the flow path so as to be displaceable in the axial direction of the flow path, and that holds the ball sheet in a state of providing a gap with the outer periphery of the ball sheet ;
A seat spring that is provided on the opposite side of the ball of the seat holding portion, presses the seat holding portion toward the ball, and presses the ball seat against the ball ;
The ball seat rotates in the circumferential direction with the rotation of the ball independently of the seat holding portion in a state where the space between the body cavity surrounded by the housing and the ball and the flow path is sealed. By doing so, it is possible to prevent uneven wear of the ball seat. On the outer periphery of the ball seat, a first locking portion is formed in the circumferential direction,
On the inner periphery of the seat holding portion, a second locking portion that fits with the first locking portion and holds the ball seat is formed in the circumferential direction.
The ball valve according to claim 1. On the outer periphery of the ball seat,
Formed at the tip of the ball seat in the insertion direction, an introduction portion having a tip diameter smaller than the tip inner diameter of the opening of the sheet holding portion;
A diameter that is formed between the introduction portion and the first locking portion, and gradually increases from the introduction portion toward the first locking portion, than a tip inner diameter of the opening of the sheet holding portion. A taper portion,
The ball valve according to claim 2, wherein an insertion guide portion is formed.   The ball valve according to any one of claims 1 to 3, wherein a gap larger than a thermal expansion allowance of the ball seat is formed between the ball seat and the seat holding portion.   The ball sheet is held by the sheet holding portion, with a surface opposite to the insertion side being flush with a front end surface of the opening of the sheet holding portion. A ball valve according to claim 1.   The ball valve according to any one of claims 2 to 5, wherein the first locking portion is a protrusion, and the second locking portion is a groove.   The ball valve according to claim 2, wherein the first locking portion is a groove portion, and the second locking portion is a projection portion.

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