Ball valve

Abstract

To provide a ball valve on which a ball seat is mounted for developing high sealability to high pressure fluid while preventing a seat retainer from being jumped out, and which is simply replaceable without giving damage to the ball seat.SOLUTION: A seat retainer 4 having ball seats 5 on one or both sides of a ball 3 having a through-hole 3a is arranged in a body 2. The seat retainer is constructed in a combination of first and second retainers 31, 32. To a seat mounting groove 36 on the front end side of the first retainer, a ball seat outer diameter face 21 is mounted in an exposed state. The outer diameter face is held by a tip inner peripheral face 42 of the second retainer and a protruded part 43 on the front end inner peripheral face of the second retainer is locked to the ball seat to prevent the jump-out in front of the ball seat. The rear inner periphery of the second retainer and the outer periphery of the first retainer are fixed by a fixing part 33, and the fixing part is located on the outer diameter side of the outer diameter face of the ball seat so that an inner peripheral face 41 of the second retainer and the outer diameter face of the ball seat do not interfere with each other when attaching / detaching the first and second retainers to / from each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a ball valve, and more particularly to a ball valve having a structure in which a ball seat is attached to a body via a seat retainer. [Background technology]

[0002] As a ball valve with this type of structure, for example, a trunnion type ball valve is known. In a trunnion type ball valve, a ball seat serving as a valve seat is attached to a body while being held by a seat retainer, and the seat retainer is resilient by the elastic force of a spring, and the ball seat is pressed against a ball to seal the fluid. A trunnion type ball valve with this structure can exhibit high sealing performance and is particularly suitable for high-pressure fluids.

[0003] In a trunnion type ball valve, when the ball seat is attached to the seat retainer as described above, there is a possibility that the ball seat may fly out or come off the seat retainer due to a pressure difference caused by high-pressure fluid, etc. To prevent this, for example, Patent Document 1 discloses a ball valve. In this ball valve, a seat with a locking portion that protrudes radially outward is fitted to the tip of a seat holder, which is a seat retainer, and the seat is clamped and fixed to the tip of the seat holder with a seat retaining ring that is screwed in place. The locked portion formed on the seat retaining ring engages with the locking portion of the seat, preventing the seat from coming loose.

[0004] Generally, the ball seat of a ball valve is a wear part, and especially when the ball seat of a high-pressure trunnion valve is made of a resin material, it is easily worn out. For this reason, the ball seat may need to be replaced periodically. In such a case, replacing the entire seat holder to which the ball seat is attached would be wasteful, so it is desirable to replace only the ball seat. For this reason, for example, in the case of Patent Document 1, the seat can be removed from the seat retainer by removing the seat retainer by removing the seat retainer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Jpn. Jpn. Published No. 58-48441 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the ball valve of Patent Document 1, when the seat with the locking portion protruding in the radial direction is fitted into the seat holder and the male thread portion formed on the seat holder and the female thread portion of the seat retaining ring are screwed together to fix them, the inner diameter of the rear end side of the seat holder is set to be approximately equal to the outer diameter of the locking portion of the seat. Due to this structure, when attaching and detaching the seat retaining ring to the seat holder, the female thread portion is likely to interfere with the seat around the locking portion.

[0007] As a result, when attaching or detaching the seat holder and the seat pressing ring, the seat pressing ring may damage the ball seat, and even if the ball seat is replaced with a new one, it may not be able to exhibit sufficient sealing performance. In particular, when the ball seat is made of a resin material, the ball seat is more likely to be damaged.

[0008] In addition, as described above, in the installation direction (axial direction) of the seat holder and seat retaining ring, the screwed portion formed by the male and female screw portions and the outer diameter of the seat's engagement portion are aligned in a straight line. Therefore, when attaching or removing these, the female screw portion may interfere with the ball seat, causing the seat retaining ring to be installed at an angle to the seat holder, or resistance to screwing may increase, making the installation and removal operations difficult.

[0009] The present invention was developed to solve the above-mentioned problems, and its purpose is to provide a ball valve which can prevent the ball seat from flying out of the seat retainer, which can be easily removed and replaced without damaging the ball seat when installing, and which exhibits high sealing properties even against high-pressure fluids after installation. [Means for solving the problem]

[0010] In order to achieve the above object, the invention of claim 1 is a ball valve in which a seat retainer having a ball seat is arranged on one or both of a ball having a through hole in a body, the seat retainer being constituted by combining a first retainer and a second retainer, the seat retainer being mounted in a seat mounting groove formed on the tip side of the first retainer with the outer diameter surface of the ball seat exposed, the outer diameter surface being held by the front inner circumferential surface of the second retainer, and a protrusion protruding from the tip inner circumferential surface of the second retainer being engaged with the ball seat to prevent the ball seat from jumping out forward, the rear inner periphery of the second retainer and the outer periphery of the first retainer being fixed by a fixing portion, the fixing portion being positioned on the outer diameter side of the outer diameter surface of the ball seat, and the inner circumferential surface of the second retainer and the outer diameter surface of the ball seat do not interfere with each other when the first retainer and the second retainer are attached or detached.

[0011] The invention of claim 2 is a ball valve in which centering surfaces of the same diameter are provided at the combined position of the outer peripheral surface of the first retainer and the inner peripheral surface of the second retainer, and each centering surface is accurately aligned.

[0012] The invention of claim 3 is a ball valve in which a gap is provided between the outer diameter side rear end of the ball seat and the outer diameter side front end of the first retainer, and the gap is exposed to the outer diameter side when the second retainer is removed from the first retainer.

[0013] The invention of claim 4 is a ball valve in which a seat taper surface is formed on the back side of the ball seat which slopes toward the ball, and a taper surface is formed on the surface of the seat mounting groove opposite this seat taper surface, and the taper angle of the taper surface is made larger than the taper angle of the seat taper surface, so that the ball seat is mounted in the seat mounting groove in a wedge shape and the two form a linear seal portion within the seat mounting groove.

[0014] The invention of claim 5 is a ball valve in which the outer end of the seat tapered surface abuts halfway on the forward inner surface of the second retainer, and the abutment surface where the tip surface of the first retainer abuts against the step surface between the fixed portion and the outer diameter surface extends toward the inner diameter side, forming a gap in the area between the seat tapered surface and the abutment surface.

[0015] The invention according to claim 6 is a ball valve in which the fixed portion is fixed by threaded engagement between the female thread of the second retainer and the male thread of the first retainer. Effect of the Invention

[0016] According to the invention of claim 1, the ball seat is mounted in the seat mounting groove of the first retainer with the outer diameter surface exposed, this outer diameter surface is held by the front inner circumferential surface of the second retainer, and the protruding portion of the front inner circumferential surface of the second retainer is engaged with the ball seat to prevent the ball seat from jumping out forward, so that the ball seat can be mounted while preventing it from jumping out or coming off the seat retainer, and such a ball seat mounting structure using the seat retainer maintains high sealing performance against high-pressure fluids. Moreover, the rear inner periphery of the second retainer and the outer periphery of the first retainer are fixed with a fixing portion, and this fixing portion is located on the outer diameter side of the ball seat, so that the inner periphery of the second retainer and the outer diameter surface of the ball seat do not interfere with each other when the first retainer and the second retainer are attached and detached, so that when the ball seat is attached, the ball seat can be easily attached, detached and replaced without damaging the ball seat, and after attachment, it is possible to exhibit high sealing performance against high-pressure fluids.

[0017] According to the invention of claim 2, the outer peripheral surface of the first retainer and the inner peripheral surface of the second retainer are provided with centering surfaces of the same diameter at the combination position of the outer peripheral surface of the first retainer and the inner peripheral surface of the second retainer, and accurate centering is achieved by the centering surfaces, so that the rear sides of the first retainer and the second retainer are fixed at their fixed positions, and the two can be attached in a state where they are aligned concentrically at these fixed positions. This allows the ball seat to be mounted between the first retainer and the second retainer in a precisely positioned state, and the ball seat can be positioned accurately relative to the ball to ensure sealing.

[0018] According to the invention of claim 3, a gap is provided between the outer diameter side rear end of the ball seat and the outer diameter side front end of the first retainer, and the gap is exposed to the outer diameter side when the second retainer is removed from the first retainer. When the second retainer is removed from the first retainer, the outer diameter side rear end of the ball seat located in the gap can be exposed along with the exposure of the outer peripheral surface of the ball seat that was held by the second retainer until then. This makes it possible to easily remove the ball seat from the seat mounting groove of the first retainer through this outer diameter side rear end portion. Furthermore, even if the ball seat is firmly fixed by being wedge-fitted into the seat mounting groove, the ball seat can be easily removed with a light force by applying force from the exposed part of the ball seat to the linear contact part between the ball seat and the first retainer by the principle of leverage, which provides excellent maintainability.

[0019] According to the invention of claim 4, the taper angle of the tapered surface of the seat mounting groove of the first retainer is made larger than the taper angle of the seat tapered surface of the ball seat, and the ball seat is mounted in the seat mounting groove in a wedge shape.When the ball seat is pressed against the ball or when fluid pressure is applied from the front side, the ball seat is pressed into the seat mounting groove in a wedge shape, and a linear seal portion with a small contact area is formed between the tapered surfaces and the seat tapered surface, which have different inclination angles, thereby improving the pressure at the time of contact and effectively suppressing fluid leakage from between the rear of the ball seat and the seat mounting groove, so-called back leakage.

[0020] According to the invention of claim 5, the outer end of the tapered seat surface is brought into contact with the middle of the forward inner circumferential surface of the second retainer, and the contact surface with which the tip end surface of the first retainer contacts is extended toward the inner diameter side with respect to the step surface between the fixing portion of the first and second retainers and the outer diameter surface of the ball seat, so that the forward side of the tapered seat surface is protruded forward from the tip end surface of the first retainer, and a predetermined gap can be formed in the area between the tapered seat surface and the contact surface. In this way, a gap of a predetermined size can be formed by making the tip end surface of the first retainer and the tapered seat surface have a predetermined positional relationship, and when the second retainer is removed from the first retainer, a part of the tapered seat surface of the ball seat located in the gap can also be exposed along with the exposure of the outer circumferential surface of the ball seat that was held by the second retainer until then. This makes it possible to easily remove the ball seat from the seat mounting groove of the first retainer through the gap or the part exposed to the outside. Furthermore, even if the ball seat is tightly fixed by being wedge-fitted into the seat mounting groove, by applying force from the exposed part of the ball seat to the linear contact part between the ball seat and the first retainer, the ball seat can be easily removed with a light force using the principle of leverage, resulting in excellent maintainability.

[0021] According to the invention of claim 6, the fixing portion is fixed by screwing together the female thread of the second retainer and the male thread of the first retainer, and this fixing portion fixes the rear inner circumference of the second retainer and the outer circumference of the first retainer, so that the fixing portion is disposed on the secondary side of the ball seat relative to the cavity side of the valve, and contact of the fixed portion with fluid can be avoided, improving corrosion resistance. There is no need to use a separate fixing member such as a bolt to fix the second retainer and the first retainer, and there is no need to treat this fixing member to be corrosion resistant, and compared to fixing with multiple bolts, the second retainer can be easily attached and detached with one touch by rotating it relative to the first retainer, and an increase in the number of parts can be suppressed. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a central vertical cross-sectional view showing a ball valve according to the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of part A in FIG. [Diagram 3] FIG. 3 is a partially enlarged schematic view of FIG. 2. [Figure 4] FIG. 4 is a schematic exploded perspective view of a seat retainer and a ball seat. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] An embodiment of the ball valve of the present invention will be described in detail below with reference to the drawings. Figure 1 is a central vertical cross-sectional view of the ball valve of the present invention, Figure 2 is an enlarged cross-sectional view of part A in Figure 1, and Figure 3 is an enlarged schematic view of Figure 2 with some parts omitted.

[0024] In the figure, the ball valve (hereinafter referred to as valve body 1) comprises a body 2, a ball 3, a seat retainer 4, a ball seat 5, a stem 6, and a coil spring 7, and takes the form of a trunnion type ball valve in which a seat retainer 4 having ball seats 5 on both sides of the ball 3 is disposed within the body 2. The valve body 1 of this embodiment is particularly suitable for use with high pressure fluids of class (nominal pressure) 150 to 2500, more preferably class 150 to 1500, and the suitable bore size is 2 inches to 24 inches.

[0025] The body 2 has an annular body 10 and caps 11 attached to both sides (upstream and downstream sides) of the annular body 10, which are made of, for example, carbon steel or stainless steel. The annular body 10 and cap 11 are fixed together with bolts and nuts 12 to form the body 2, and a flow path is formed inside the body 2. An attachment recess 14 for attaching the seat retainer 4 is formed on the side of the cap 11 opposite the ball 11.

[0026] A ball 3 is rotatably attached within the body 2 via a stem 6 consisting of an upper stem 6a and a lower stem 6b, and a seat retainer 4 having a ball seat 5 is disposed on both the upstream and downstream sides of the ball 3 via a mounting recess 14. The ball 3 is made of, for example, stainless steel, and has a through hole 3a that can communicate with a body flow path 13.

[0027] The ball seat 5 is formed into an annular shape from a resin material such as PTFE (polytetrafluoroethylene), nylon, PEEK (polyether ether ketone), etc. On the side of the ball seat 5 that comes into contact with the ball 3, an annular seal surface 20 having an inclined or rounded cross section that can be sealed to the outer circumferential surface of the ball 3 is provided, while on the outer circumferential side of the ball seat 5, a flat outer diameter surface 21 is formed into an annular shape.

[0028] The back surface of the ball seat 5, i.e., the side that is attached to the seat retainer 4, has a seat taper surface 22 formed in an annular shape that slopes toward the ball 3, in other words, its rear side slopes from the outer diameter side toward the inner diameter side toward the rear.

[0029] 2 to 4, the seat retainer 4 includes two retainer members, a first retainer 31 and a second retainer 32 having a function of a retainer ring, i.e., a function of mounting the ball seat 5 to the first retainer 31. The first retainer 31 and the second retainer 32 are formed into a substantially cylindrical shape from a metal material such as carbon steel or stainless steel. The seat retainer 4 is assembled together by fixing the rear inner periphery of the second retainer 32 and the outer periphery of the first retainer 31 with a fixing portion 33. In this embodiment, the front (leading end) side of the seat retainer 4 is the side facing the ball 3, and the rear (rear end) side of the seat retainer 4 is the end side opposite the leading end (leading end).

[0030] The fixing portion 33 is provided on the seat retainer 4 so as to be located on the outer diameter side of the outer diameter surface 21 of the ball seat 5. This fixing portion 33 is composed of a female thread 34 formed on the inner circumference on the rear end side of the second retainer 32 and a male thread 35 formed on the outer circumference of the front end of the first retainer 31, and the first retainer 31 and the second retainer 32 are fixed together by a threaded connection between the female thread 34 and the male thread 35, and the ball seat 5 is movably attached between them.

[0031] A concave seat mounting groove 36 into which the ball seat 5 can be mounted is formed in an annular shape on the tip side of the first retainer 31 of the seat retainer 4, and a tapered surface 37 is formed on the surface of this seat mounting groove 36 that faces the seat tapered surface 22 of the ball seat 5 described above. The taper angle θ1 of this tapered surface 37 with respect to the flow path direction is set to be larger than the taper angle θ2 of the seat tapered surface 22 with respect to the flow path direction. As a result, when the ball seat 5 is mounted on the seat retainer 4, the ball seat 5 is mounted in a wedge shape in the seat mounting groove 36, and at the same time, after mounting, the seat tapered surface 22 and the tapered surface 37 are in an annular line contact state, whereby a linear seal portion 38 is formed in an annular shape between the ball seat 5 and the second retainer 32.

[0032] At the position on the outer circumferential surface of the first retainer 31 where the first retainer 31 is to be combined with the second retainer 32, specifically, at the rear side of the position of the male thread 34, an annular centering surface 40 is provided so as to be larger in diameter than the male thread 34. In this way, the outer circumferential surface on the tip side of the first retainer 31 and the inner circumferential surface 42 on the front side of the second retainer 32, which will be described later, are both shaped to be gradually enlarged or reduced in diameter from the front, so that all cylindrical surfaces can be processed without changing the grip of each component during processing, making it easy to center each cylindrical surface. In addition, since the centering surface 40 is at the outermost diameter position, it can be visually observed from the rear of the tip side of the first retainer 31, and it can be confirmed whether the centering of the surface 40 is properly performed. As a result, the first retainer 31 and the second retainer 32 can be combined in a state of being accurately centered, so that the ball seat 5 can be fixed at an accurate position, and particularly good sealing performance between the ball seat 5 and the ball 3 can be obtained.

[0033] On the inner surface 41 of the second retainer 32, a ring-shaped front inner surface 42 is formed on the front side where the ball seat 5 is attached, and a protrusion 43 for engaging with the ball seat 5 is formed on the tip side of this front inner surface 42 so as to protrude toward the inner side.

[0034] At the position on the inner surface of the second retainer 32 where it is combined with the first retainer 31, specifically, rearward of the position of the female thread 34, a centering surface 44 of approximately the same diameter as the centering surface 40 of the first retainer 31 is provided so as to be larger in diameter than the female thread 34.

[0035] When the female thread 34 and the male thread 35 are screwed together, the centering surface 44 of the second retainer 32 and the centering surface 40 of the first retainer surface 31, which have approximately the same diameter, are in close contact with each other, and the second retainer 32 and the first retainer 31 are assembled with accurate centering at the centering surfaces 44, 40.

[0036] When combining the ball seat 5 and second retainer 32 with the above-mentioned first retainer 31, the seat tapered surface 22 of the ball seat 5 is fitted into the seat mounting groove 36 of the first retainer 31, and the ball seat 5 is mounted in a state in which the outer diameter surface 21 of the ball seat 5 is exposed to the outside from the seat mounting groove 36, and in this state, the second retainer 32 is assembled to the first retainer 31. At that time, the ball seat outer diameter surface 21 is held by the front inner circumferential surface 42 of the second retainer 32, and a protruding portion 43 protruding from the tip inner circumferential surface of the second retainer 32 is engaged with the front side of the ball seat 5 (the side facing the ball 3), preventing the ball seat 5 from jumping out forward.

[0037] After assembly, an appropriate amount of clearance C is provided between the ball seat 5 and the first retainer 31, and the ball seat 5 is provided so as to be movable in the flow path direction via the clearance C. The clearance C may be formed, for example, with a length of about 0.5 to 1.2 mm in the flow path direction depending on the size of the valve.

[0038] In this case, the rear inner periphery of second retainer 32 and the outer periphery of first retainer 31 are fixed by fixing portion 33 consisting of female threads 34 and male threads 35, and this fixing portion 33 is positioned on the outer diameter side of the outer diameter surface 21 of ball seat 5. This prevents interference between inner periphery surface 41 of second retainer 32 and outer diameter surface 21 of ball seat 5 when first retainer 31 and second retainer 32 are attached or detached.

[0039] After the ball seat 5 is attached to the seat retainer 4, the outer end 22a of the seat tapered surface 22 is arranged to abut halfway against the front inner circumferential surface 42 of the second retainer 32. In the second retainer 32, a step surface 50 is provided in a direction approximately perpendicular to the flow path 13 between the fixing portion 33 formed by the female thread 34 and the male thread 35 and the outer diameter surface 21 of the ball seat 5.

[0040] The first retainer 31 has an abutment surface 53 on the tip end surface side that abuts against the step surface 50, and the abutment surface 53 is provided so as to extend to the inner diameter side. In this manner, the abutment surface 53 is provided so as to be longer in the radial direction than the step surface 50, so that when the ball seat 5 is attached to the first retainer 31 and the second retainer 32, a gap S is provided between the outer diameter side rear end 60 of the ball seat 5 and the outer diameter side tip end of the first retainer 31. Then, when the second retainer 32 is removed from the first retainer 31, the gap S is exposed to the outer diameter side. In this embodiment, a gap S of a predetermined size is formed in an annular shape in the region between the seat tapered surface 22 and the abutment surface 53.

[0041] Furthermore, because step surface 50 and abutment surface 53 abut against each other with their smooth surfaces, it is also possible to align first retainer 31 and second retainer 32 in a direction along the flow path. This, combined with the radial centering by centering surface 40 described above, allows first retainer 31 and second retainer 32 to be assembled with extremely accurate centering, so that even though the retainer that holds ball seat 5 is divided into two, ball seat 5 can be held accurately and high sealing performance with ball 3 can be obtained.

[0042] The outer diameter surface 21 of the ball seat 5 is provided with a single or multiple communication grooves 55 that communicate with the cavity portion 51 provided in the valve body 1, and in this embodiment, as shown in Fig. 4, three communication grooves 55 are provided at equal intervals on the outer diameter surface 21. When the first retainer 31 and the second retainer 32 are combined, the communication grooves 55 communicate with the gap S, whereby, in the valve body 1, the gap S communicates with the cavity portion 51.

[0043] The integrated seat retainer 4 is attached to the mounting recess 14 of the cap 11 with the first retainer 31 passed through the coil spring 7, and is assembled into the valve body 1 in a state where it is biased toward the ball 3 by the elastic force of the coil spring 7. With this configuration, in the valve body 1, the seat retainer 4 is resiliently biased by the coil spring 7, and the sealing surface 20 of the ball seat 5 attached to the seat retainer 4 is pressed against the outer circumferential surface of the ball 3, ensuring a seal between the ball seat 5 and the ball 3 and preventing fluid leakage.

[0044] In the above embodiment, the valve body 1 is configured such that the seat retainer 4 having the ball seat 5 is disposed on both sides (first and secondary sides) of the ball 3, but the valve body 1 may also be configured such that the seat retainer 4 having the aforementioned ball seat 5 is disposed on one side of the ball 3.

[0045] In the case where the seat retainer 4 is constructed by attaching a ball seat 5 between the first retainer 31 and the second retainer 32, the fixing portion 33 may have a structure other than a screw connection using a female thread 34 and a male thread 35. For example, the fixing portion may be provided by an interlocking structure, and the first retainer 31 and the second retainer 32 may be fixed by this interlocking fixing portion.

[0046] The gap S may be provided between the outer diameter side rear end of the ball seat 5 and the outer diameter side tip of the first retainer 31, and by providing an appropriate combination structure of the ball seat 5 and the first retainer 31, gaps S of various shapes can be provided between the outer diameter side rear end of the ball seat 5 and the outer diameter side tip of the first retainer 31.

[0047] 2 to 4, instead of the communicating groove 55 provided in the outer diameter surface 21 of the ball seat 5 as described above, pressure equalizing holes 52 indicated by two-dot chain lines that communicate with a cavity portion 51 provided in the valve body 1 may be provided at a predetermined interval near the outer diameter side of the stepped surface 50 of the second retainer 32. In this case, a groove-shaped communicating portion 54 indicated by two-dot chain lines that communicates from the inner diameter side to the outer diameter side of the abutment surface 53 of the first retainer 31 that abuts against the stepped surface 50 of the second retainer 32 may be provided at a single or multiple locations, so that when the first retainer 31 and the second retainer 32 are assembled, the pressure equalizing hole 52 of the second retainer 32 can be communicated with the above-mentioned gap S via the communicating portion 54. This also makes it possible for the gap S in the valve body 1 to communicate with the cavity portion 51 through the communication portion 54 and the pressure equalizing hole 52. In this embodiment, for ease of explanation, both the case where a communicating groove 55 (dashed line) is provided and the case where a pressure equalizing hole 52 and a communicating portion 54 (dash-dotted line) are provided as structures for communicating between the cavity 51 and the gap S (the rear surface of the ball seat 5) are shown in the same figure, but in reality, only one of these cases may be applied.

[0048] In this case, an appropriate jig can be inserted into one of the multiple pressure equalizing holes 52 that is easiest to work on, and the second retainer 32 can be rotated relative to the first retainer 31 using the jig, making it easy to attach and detach the second retainer 32. Furthermore, even if no pressure equalizing hole 52 is provided in this manner, it is possible to form a non-through jig hole 56, as shown in Figure 4, in the tip surface of second retainer 32 and use this to easily rotate second retainer 32 using a jig.

[0049] As long as the taper angle θ1 of the taper surface 37 is larger than the angle θ2 of the seat taper surface 22, these taper angles θ1 and θ2 can be set arbitrarily. This makes it possible to set the linear seal portion 38 at any radial position depending on the bore of the valve body 1, the magnitude of the fluid pressure, etc. In this case, if the distance from the center of the flow path 13 to the seal portion 38 is long, when pressure is applied to the ball seat 5, the force acts too strongly and the ball seat 5 is likely to pop out, so it is better to keep the distance from the center of the flow path 13 to the seal portion 38 short. In addition, the ball seat 5 is prevented from popping out by the protrusion 43 of the second retainer 32. From the viewpoint of obtaining this pop-out prevention effect effectively, the greater the width of the protrusion 43 that engages with the ball seat 5, the better. However, in order not to interfere with the operation of the ball 3, it is preferable that the width be approximately 1 / 3 of the radial thickness of the ball seat 5.

[0050] Next, the operation of the valve body 1 in the above embodiment of the present invention will be described. 1 to 3, the valve body 1 in this embodiment is configured so that protrusion 43 formed on second retainer 32 engages with the front side of ball seat 5 to prevent ball seat 5 from jumping out forward, so that an off-the-shelf ball seat can be used without special processing such as providing ball seat 5 with a step for engaging with second retainer 32, and after ball seat 5 is attached to seat retainer 4, it is possible to reliably prevent it from jumping out or coming out. Therefore, even when high-pressure fluid flows inside the valve body 1, the attached state of ball seat 5 to seat retainer 4 can be maintained, ensuring high sealing performance.

[0051] In this case, when fluid pressure is applied to the flow path 13 side when the valve is open, the fluid tries to flow from the gap S to the cavity portion 51 side. Due to this fluid pressure and the pressure during sealing, a force F acts on the ball seat 5 in the upper left direction as shown by the arrow in Figures 2 and 3, and this force F acts as a vector in the X and Y directions due to forces Fx and Fy. This is an example of the force applied to the sealing point of the ball seat 5, and fluid pressure is applied to all other parts of the ball seat 5 that come into contact with the fluid.

[0052] As described above, because the clearance C is provided between the ball seat 5 and the first retainer 31, the ball seat 5 is pressed leftward (toward the rear) by the force Fx relative to the first retainer 31. As a result, the seat tapered surface 22 and the tapered surface 37 are strongly pressed against each other in the seal portion 38, forming a linear seal point, thereby preventing the fluid from leaking from the seat back surface side to the cavity portion 51 side.

[0053] At this time, a force Fy is applied from the outer diameter surface 21 of the ball seat 5 in the direction of the forward inner surface 42 of the second retainer 32, but since the outer diameter surface 21 and the forward inner surface 42 abut by surface contact and no force acts locally from the ball seat 5 on the second retainer, there is no risk of the area around the outer diameter surface 21 of the ball seat 5 being scratched or damaged.

[0054] Furthermore, according to this embodiment, the outer diameter surface 21 of the ball seat 5 can be held by the front inner surface 42 of the second retainer 32, which is a uniform circumferential surface that is free of steps in the depth direction. This means that the force in the Fy direction can be effectively received and twisting in the upper left direction that is prone to occur in the ball seat 5 can be suppressed, which is more advantageous in preventing the ball seat 5 from popping out and also allows the ball seat 5 to be positioned more accurately.

[0055] The fixing portion 33 that fixes the rear inner circumference of the second retainer 32 and the inner circumference of the first retainer 31 is provided so as to be located on the outer diameter side of the outer diameter surface 21 of the ball seat 5, and the inner circumferential surface 41 of the second retainer 32 and the outer diameter surface 21 of the ball seat 5 do not interfere with each other when the first retainer 31 and the second retainer 32 are attached and detached, so there is no risk of the second retainer 32 scratching and damaging the vicinity of the outer diameter surface 21 of the ball seat 5. This makes it possible to replace the ball seat 5 while maintaining this functionality, while ensuring high sealing performance by forming the ball seat 5 from a resin material. In this way, it is necessary to replace only the ball seat 5 of the seat retainer 4, and there is no need to replace the first retainer 31 and the second retainer 32, so that the first and second retainers 31 and 32 can be reused.

[0056] As described above, the inner surface 41 of the second retainer 32 and the outer diameter surface 21 of the ball seat 5 are positioned radially offset, so that when the second retainer 32 is screwed into the first retainer 31, its inner surface 41 (female thread 34) is prevented from coming into contact with the ball seat 5, preventing the second retainer 32 from being installed in an inclined state, and no unnecessary resistance is added when screwing, resulting in excellent maintainability.

[0057] When the first retainer 31 and the second retainer 32 are fixed together, the centering surface 40 of the first retainer 31 and the centering surface 44 of the second retainer 32 come into close contact, and these centering surfaces 40, 44 absorb the radial play caused by the engagement of the male thread 35 and the female thread 34, allowing the first retainer 31 and the second retainer 32 to be integrated while being accurately centered while preventing radial misalignment and rattling. Therefore, the ball seat 5 attached to the seat retainer 4 can be positioned in a centered state with respect to the ball 3, and the accurate contact position of the ball seat 5 and the ball 3 is maintained during the operation of the valve body 1 from valve closing to valve opening, providing excellent sealing properties.

[0058] In a ball valve, it is important to accurately determine the contact position between the ball 3 and the ball seat 5 in order to obtain reliable sealing, and for this purpose, it is important that the ball seat is held in an accurate position by a seat retainer or the like. Normally, a seat retainer is made of a single member, so that the holding portion of the ball seat is easily formed without deviation. In this embodiment, the ball seat 5 is held by two members, the first retainer 31 and the second retainer 32, so that it is usually not easy to position the ball seat 5. In contrast, as described above, in this embodiment, the first retainer 31 and the second retainer 32 can be accurately positioned by the centering surface 40 and the surface contact between the step surface 50 and the abutment surface 53, so that the ball seat 5 can also be held in the correct position.

[0059] This is an installation structure for the ball seat 5, which is attached so as to sandwich the ball seat 5 between the first retainer 31 and the second retainer 32, and as described above, this ball seat 5 is an off-the-shelf part, and therefore there is no need to process a special shape such as a step. When fluid pressure is applied, there is no risk of the force being concentrated on one part of the ball seat 5 as in the case where a step or the like is provided, so deformation or damage to the ball seat 5 can be prevented and sealing properties can be maintained, and the ball seat 5 can be easily removed from the first retainer 31 and the second retainer 32.

[0060] Since the seat tapered surface 22 is formed on the back side of the ball seat 5 and the tapered surface 37 is formed on the seat mounting groove 36, the taper angle θ1 of the tapered surface 37 is made larger than the taper angle θ2 of the seat tapered surface 22, and the ball seat 5 is mounted in the seat mounting groove 36 in a wedge shape, the ball seat 5 is firmly mounted to the first retainer 31 by a wedge action, and a linear seal portion 38 is formed in the seat mounting groove 36 by the ball seat 5 and the first retainer 31, and the surface pressure can be improved by this linear seal portion 38. Moreover, since the sealing pressure of the seal portion 38 increases with an increase in fluid pressure, leakage of fluid from the back side of the ball seat 5, i.e., so-called back leakage, can be reliably prevented even for high-pressure fluids.

[0061] Since the outer end 22a of the seat tapered surface 22 abuts on the middle of the front inner circumferential surface 42 of the second retainer 32 and the abutment surface 53 with which the tip surface of the first retainer 31 abuts extends toward the inner diameter side with respect to the step surface 50 between the fixed portion 33 and the outer diameter surface 21, forming a gap S in the region between the seat tapered surface 22 and the abutment surface 53, this gap S can be provided in a shape that widens toward the outer diameter. By providing the gap S in this manner, the gap S is exposed to the outer diameter side when the second retainer 32 is removed from the first retainer 31, so that even if the ball seat 5 is pressed into the seat mounting groove 36 of the first retainer 31 by fluid pressure, the second retainer 32 can be removed from the first retainer 31 and the ball seat 5 can be easily removed by easily hooking a fingertip or a tool on the portion of the ball seat 5 exposed to the outside through the exposed gap S.

[0062] A step surface 50 is provided on second retainer 32 and gap S is connected to cavity portion 51 in valve body 1. Therefore, even if pressure infiltrates into the rear side of ball seat 5 from between ball seat 5 and second retainer 32 when the valve is fully open, the pressure in gap S on the rear side of ball seat 5 can be ensured to be equal to the pressure in cavity portion 51, preventing the accumulation of pressure on the rear side of ball seat 5 and preventing the generation of a force in the pushing direction on ball seat 5 due to the accumulation of this fluid pressure, and reliably preventing ball seat 5 from popping out.

[0063] The fixing portion 33 is fixed by a screw connection between the female thread 34 of the second retainer 32 and the male thread 35 of the first retainer 31. Therefore, by attaching the ball seat 5 to the second retainer 32 in a temporary attached state and then attaching the first retainer 31 to the second retainer 32 by screw connection, the ball seat 5 can be accurately integrated with the seat retainer 4 in a predetermined position.

[0064] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the description of the embodiment, and various modifications can be made without departing from the spirit of the invention described in the claims of the present invention. [Explanation of symbols]

[0065] 1 Valve body 2 Body 3. Ball 3a Through hole 4 Seat Retainer 5 Ball seat 21 Outer diameter surface of ball seat 22 Seat tapered surface 22a Outer end of seat tapered surface 31 First retainer 32 Second retainer 33 Fixed part 34 Female thread 35 Male thread 36 Seat mounting groove 37 Tapered Surface 38 Seal Part 40, 44 Centering surface 41 Inner peripheral surface of second retainer 42 Inner peripheral surface of second retainer 43 Protrusion 50 Step surface 51 Cavity 52 Pressure equalizing hole 53 Contact surface 54 Communication part 60 Outer diameter rear end 61 Outer diameter side tip S Gap θ1 Taper angle of tapered surface θ2: Taper angle of the seat taper surface

Claims

1. a seat retainer having a ball seat on one or both of a ball having a through hole in a body, the seat retainer being constructed by combining a first retainer and a second retainer, the seat retainer being mounted in a seat mounting groove formed in a tip side of the first retainer with an outer diameter surface of the ball seat exposed, the outer diameter surface being held by a front inner circumferential surface of the second retainer, a protrusion protruding from the tip inner circumferential surface of the second retainer engaging with the ball seat to prevent the ball seat from jumping out forward, a rear inner periphery of the second retainer and an outer periphery of the first retainer are fixed by a fixing part, the fixing part being positioned outer diameter side of the outer diameter surface of the ball seat, so that the inner circumferential surface of the second retainer and the outer diameter surface of the ball seat do not interfere with each other when the first retainer and the second retainer are attached or detached.

2. 2. The ball valve according to claim 1, wherein the outer peripheral surface of the first retainer and the inner peripheral surface of the second retainer are provided with respective centering surfaces of the same diameter at a position where they are joined, and accurate centering is achieved by each centering surface.

3. 3. The ball valve according to claim 1, wherein a gap is provided between an outer diameter side rear end of the ball seat and an outer diameter side front end of the first retainer, and the gap is exposed to the outer diameter side when the second retainer is removed from the first retainer.

4. 3. A ball valve as claimed in claim 1, wherein a seat taper surface is formed on the back side of the ball seat, the seat mounting groove has a surface facing the seat taper surface, the taper angle of the taper surface is made larger than the taper angle of the seat taper surface, the ball seat is mounted in the seat mounting groove in a wedge shape, and the two form a linear seal portion within the seat mounting groove.

5. 5. The ball valve as described in claim 4, wherein an outer end of the seat tapered surface abuts halfway against a forward inner peripheral surface of the second retainer, and an abutment surface where the tip surface of the first retainer abuts against a step surface between the fixed portion and the outer diameter surface is extended toward the inner diameter side, thereby forming the gap in the area of ​​the seat tapered surface and the abutment surface.

6. 2. The ball valve according to claim 1, wherein the fixed portion is fixed by a threaded connection between the female thread of the second retainer and the male thread of the first retainer.

Images