Eccentric semi-ball valve with single valve seat and two-way sealing function

Abstract

The utility model discloses a single valve seat two-way sealing eccentric semi-ball valve which comprises a valve body, a valve cap and a semi-ball body, a valve seat is arranged between the semi-ball body and the valve cap, and a limiting plate for limiting the valve seat to be separated from the semi-ball body is arranged on the side, facing the semi-ball body, of the valve cap. An annular support matched with the inner wall of the valve bonnet is arranged on the tail portion of the valve seat, a first annular containing cavity is formed in the inner wall of the annular support, a second annular containing cavity is formed in the outer wall of the annular support, a first sealing ring is arranged in the first annular containing cavity, a second sealing ring is arranged in the second annular containing cavity, and the first sealing ring and the second sealing ring are arranged in the valve bonnet. An elastic piece for providing pretightening force for the valve seat is arranged between the annular support and the valve seat. The ball valve is stable in structure and better in sealing effect, torque needed for opening the ball valve can be reduced, the problem of inner leakage caused by abrasion of the contact face of the valve seat and the hemisphere can be solved, and the service life of the ball valve is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model belongs to valve technical field, especially a single valve seat two -way sealing eccentric half -ball valve. BACKGROUND

[0002] The eccentric half -ball valve mainly is sealed by the contact of ball and valve seat, and the extrusion between ball and seat forms the specific pressure needed for sealing, thereby realizing the sealing effect. The single valve seat structure is widely used in valve design due to its no dead zone feature, and the eccentric half -ball valve also adopts the single valve seat structure to realize sealing. In the low medium pressure working condition, the single valve seat design can ensure the sealing of the flow passage and meet the low torque feature of the valve stem, and the ball valve can be quickly opened. If it is a high medium pressure working condition, the high medium pressure will extrude the ball and the valve seat. In order to ensure the sealing effect between the valve seat and the ball, a relatively elastic elastic member is generally provided to provide pre-tightening force for the valve seat to realize the sealing between the valve seat and the ball. Due to the relatively large elasticity of the elastic member, the extrusion between the valve seat and the ball will be more serious, the friction between the valve seat and the ball will be larger, and a larger torque will be needed to overcome when the ball valve is opened. Not only will it reduce the service life of the ball valve, but also the contact surface of the valve seat and the ball will be worn and leak.

[0003] The prior art discloses a single-valve-seat bidirectional sealing structure ball valve disclosed by Chinese patent authorization publication No. CN203548978U. When the medium upstream pressure is higher than the medium downstream pressure, the sealing direction one is normal sealing, that is, when the medium upstream inlet end pressure is greater than the downstream outlet end pressure, the medium upstream inlet end pressure pushes the valve seat and the ball body to be tightly sealed, and the sealing principle is that: when the medium upstream pressure is greater than the medium downstream pressure, the upstream medium pressure Fl+ the spring compensation pre-tightening force-the reverse pushing force F2 of the downstream medium to the valve seat realizes the sealing of the ball body and the valve seat; when the medium downstream pressure is higher than the medium upstream pressure, the sealing direction two is reverse sealing, that is, when the medium downstream pressure is greater than the medium upstream pressure, the medium downstream pressure pushes the valve seat and the ball body to be tightly sealed, and the sealing principle is that: when the medium downstream pressure is greater than the upstream pressure, the pressure Fl of the downstream medium into the back of the valve seat+the spring compensation pre-tightening force-the positive pushing force F2 of the downstream medium to the valve seat realizes the sealing of the ball body and the valve seat; in the above scheme, the upstream medium pressure Fl-the reverse pushing force F2 of the downstream medium to the valve seat is greater than zero, and the pressure Fl of the downstream medium into the back of the valve seat-the positive pushing force F2 of the downstream medium to the valve seat is greater than zero, therefore, in the process of realizing the bidirectional sealing, in addition to the spring compensation pre-tightening force, the medium pressure difference on both sides of the valve seat also provides the pre-tightening force for pressing the ball body, the sealing between the ball body and the valve seat can be realized by the medium pressure difference, therefore, the sealing between the ball body and the valve seat can be realized by appropriately increasing the pressure difference on both sides of the valve seat and reducing the spring compensation pre-tightening force, after reducing the spring compensation pre-tightening force, the extrusion between the valve seat and the ball body can be reduced, the friction between the valve seat and the ball body can be reduced, and the torque required for opening the ball valve can be reduced by the above-mentioned mode. However, the above scheme still has the following problems: the sealing ring is pushed by the medium, the sealing ring can be deformed greatly under high medium pressure, if the sealing ring is deformed, the sealing surface between the valve seat and the valve body can be changed, the medium pressure surface on both sides of the valve seat can be changed, and therefore, the pressure difference on both sides of the valve seat can be changed, that is, the pressure difference between the upstream medium pressure Fl and the reverse pushing force F2 of the downstream medium to the valve seat and the pressure difference between the pressure Fl of the downstream medium into the back of the valve seat and the positive pushing force F2 of the downstream medium to the valve seat can be changed, therefore, the actual sealing pressure principle can be inconsistent with the design principle, the design of the spring compensation pre-tightening force can be unreasonable, and finally, the leakage problem can occur due to the poor sealing between the valve seat and the ball body.

[0004] Therefore, it is necessary to provide a single-valve-seat bidirectional sealing eccentric half-ball valve to solve the above technical problems.

Realize new type

[0005] The utility model discloses a main purpose lies in providing a single valve seat two -way sealing eccentric half -ball valve, stable structure, and the sealing effect is better, and still can reduce the torque required to open ball valve, can solve the problem of the contact surface of valve seat and half -spherical body appears abrasion and occurs internal leakage, improve the service life of ball valve.

[0006] The utility model discloses a single valve seat two -way sealing eccentric half -ball valve, its including valve body, install the bonnet of valve body opposite side and install the half -spherical body of valve body inside, the half -spherical body with the bonnet between being provided with the valve seat of realizing clearance seal, the bonnet, the valve seat, the half -spherical body and the inner chamber of valve body jointly form medium flow channel, the bonnet is provided with the limiting plate of limiting the valve seat to separate the half -spherical body on the side to the half -spherical body, the tail of valve seat is provided with the annular support of cooperation with the inner wall of bonnet, the inner wall on the annular support is provided with first annular accommodating cavity, and the outer wall is provided with second annular accommodating cavity, is provided with first sealing ring in first annular accommodating cavity and realizes the clearance seal between the annular support and valve seat, is provided with second sealing ring in second annular accommodating cavity and realizes the clearance seal between the annular support and bonnet, and the annular support with valve seat between being provided with the elastic member for the valve seat provides the elastic member of pre -tightening force.

[0007] Further, the bonnet is provided with a multi-stage stepped surface structure at the position in contact with the valve seat, the multi-stage stepped surface structure includes a first stepped surface at the left end, a second stepped surface vertically extending upward from the right end of the first stepped surface, a third stepped surface horizontally extending rightward from the upper end of the second stepped surface, and a fourth stepped surface vertically extending upward from the right end of the third stepped surface.

[0008] Further, the second stepped surface and the left end surface of the annular support are provided with a first gap for medium flow, the third stepped surface contacts the outer circle of the annular support, and the second sealing ring is used to realize the gap sealing between the third stepped surface and the outer circle of the annular support.

[0009] Further, the valve seat includes an inclined surface towards the half-spherical body, a limiting surface extending upward from the upper end of the inclined surface and in contact with the limiting plate, a first mating surface extending horizontally leftward from the left end of the limiting surface and in cooperation with the third stepped surface, a mounting surface extending downward from the left end of the first mating surface and towards the annular support, a first sealing surface extending horizontally leftward from the lower end of the mounting surface and in contact with the outer circle of the annular support, and an end surface extending vertically downward from the left end of the first sealing surface and towards the bonnet, the end surface being oppositely arranged with the inclined surface.

[0010] Further, the mounting surface, the third step surface, the right end surface of the annular support and the first sealing surface form a containing cavity for temporarily storing medium.

[0011] Further, a second gap for medium to flow into or out of the containing cavity is arranged between the first matching surface and the third step surface.

[0012] Further, a mounting groove for mounting the elastic member is arranged on the mounting surface, one end of the elastic member extends into the mounting groove and the other end is arranged on the right end surface of the annular support.

[0013] Further, the first sealing ring is used to realize gap sealing between the first sealing surface and the inner ring of the annular support, the end of the first sealing surface matches the first step surface, and a third gap for medium to flow through is arranged between the first sealing surface and the first step surface.

[0014] Further, the inclined surface comprises an outer convex profiling surface at the upper end which is in contact with the outer wall of the hemisphere to realize sealing and an inner concave surface at the lower end which forms a fourth gap with the hemisphere.

[0015] Further, the limiting plate is arranged on the fourth step surface through a screw, and the lower end of the limiting plate extends to the right side of the limiting surface.

[0016] Compared with the prior art, the single-valve-seat bidirectional sealing eccentric hemispherical valve has the following beneficial effects:

[0017] (1) During bidirectional flow of medium, bidirectional sealing can be realized, in addition to the pre-tightening force provided by the elastic member to the valve seat, the medium pressure difference on both sides of the valve seat also provides a pressing force for the valve seat to press the hemisphere, and the medium pressure difference from one side of the valve seat to press the hemisphere, the medium pressure difference can be used to realize the auxiliary sealing between the valve seat and the hemisphere, therefore, the elastic member does not need to be set to high elasticity, the elasticity of the elastic member can be appropriately reduced, the extrusion between the valve seat and the hemisphere can be reduced after reducing the pre-tightening force of the elastic member, the friction between the valve seat and the hemisphere will be smaller, the torque required for opening the ball valve can be reduced, the problem of internal leakage caused by wear of the contact surface between the valve seat and the hemisphere can be solved, and the service life of the ball valve is improved.

[0018] (2) The annular support is arranged to support and limit the first sealing ring and the second sealing ring, and the first sealing ring and the second sealing ring are limited on the inner wall and the outer wall of the annular support, so that the first sealing ring and the second sealing ring can play a sealing role, the medium can be prevented from flowing from the containing cavity into the first gap or from flowing from the first gap into the containing cavity, and the first sealing ring and the second sealing ring can be supported and limited by the annular support, so that the first sealing ring and the second sealing ring are prevented from being deformed to affect the sealing between the valve seat and the hemispherical body, the annular support can make the structure of the entire ball valve more stable, and the sealing effect is better. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a sectional view structure schematic diagram of a single-valve-seat bidirectional sealing eccentric hemispherical valve of an embodiment of the utility model;

[0020] Figure 2 It is a sectional view structure schematic diagram of a single-valve-seat bidirectional sealing eccentric hemispherical valve of an embodiment of the utility model; Figure 1 It is an enlarged structure schematic diagram of a part A of the utility model;

[0021] Figure 3 It is a medium first flow direction sealing stress structure schematic diagram of an embodiment of the utility model;

[0022] Figure 4 It is a medium second flow direction sealing stress structure schematic diagram of an embodiment of the utility model;

[0023] Figures in the drawing represent:

[0024] 100 - single-valve-seat bidirectional sealing eccentric hemispherical valve;

[0025] 1 - valve body;

[0026] 2 - valve cap, 21 - first step surface, 22 - second step surface, 23 - third step surface, 24 - fourth step surface;

[0027] 3 - hemispherical body; 4 - valve rod; 5 - bottom shaft;

[0028] 6 - valve seat, 61 - inclined surface, 611 - outer convex profiling surface, 612 - inner concave surface, 62 - limiting surface, 63 - first matching surface, 64 - mounting surface, 641 - mounting groove, 65 - first sealing surface, 66 - end surface;

[0029] 7 - limiting plate;

[0030] 8 - annular support, 81 - first annular containing cavity, 82 - second annular containing cavity, 83 - first sealing ring, 84 - second sealing ring;

[0031] 9 - elastic member; 10 - containing cavity; 20 - screw.

DETAILED DESCRIPTION

[0032] Referring to Figures 1-4 The embodiment is a single-valve-seat bidirectional sealing eccentric half-ball valve 100, which comprises a valve body 1, valve covers 2 installed on opposite sides of the valve body 1, a half-ball body 3 installed inside the valve body 1, a valve rod 4 installed on the upper end of the half-ball body 3, and a bottom shaft 5 installed at the bottom of the half-ball body 3. A valve seat 6 for realizing gap sealing is arranged between the half-ball body 3 and the valve cover 2. The valve cover 2, the valve seat 6, the half-ball body 3, and the inner cavity of the valve body 1 jointly form a medium flow channel. The valve cover 2 is provided with a limiting plate 7 on the side facing the half-ball body 3 to limit the valve seat 6 from separating from the half-ball body 3. An annular support 8 is arranged on the tail of the valve seat 6 and cooperates with the inner wall of the valve cover 2. The inner wall of the annular support 8 is provided with a first annular accommodating cavity 81, and the outer wall is provided with a second annular accommodating cavity 82. A first sealing ring 83 is arranged in the first annular accommodating cavity 81 to realize gap sealing between the annular support 8 and the valve seat 6. A second sealing ring 84 is arranged in the second annular accommodating cavity 82 to realize gap sealing between the annular support 8 and the valve cover 2. An elastic member 9 is arranged between the annular support 8 and the valve seat 6 to provide pre-tightening force for the valve seat 6.

[0033] The valve cover 2 is provided with a multi-stage stepped surface structure at the position in contact with the valve seat 6, as shown in Figure 2 The multi-stage stepped surface structure comprises a first stepped surface 21 at the left end, a second stepped surface 22 vertically extending upwards from the right end of the first stepped surface 21, a third stepped surface 23 horizontally extending to the right from the upper end of the second stepped surface 22, and a fourth stepped surface 24 vertically extending upwards from the right end of the third stepped surface 23. The second stepped surface 22 is provided with a first gap for medium flow at the left end of the annular support 8. The third stepped surface 23 is in contact with the outer circle of the annular support 8, and the second sealing ring 84 is used to realize gap sealing between the third stepped surface 23 and the outer circle of the annular support 8.

[0034] As shown in Figure 2 The valve seat 6 comprises an inclined surface 61 facing the half-ball body 3, a limiting surface 62 extending upwards from the upper end of the inclined surface 61 and in contact with the limiting plate 7, a first matching surface 63 horizontally extending to the left from the left end of the limiting surface 62 and matching with the third stepped surface 23, a mounting surface 64 extending downwards from the left end of the first matching surface 63 and facing the annular support 8, a first sealing surface 65 horizontally extending to the left from the lower end of the mounting surface 64 and in contact with the outer circle of the annular support 8, and an end surface 66 vertically extending downwards from the left end of the first sealing surface 65 and facing the valve cover 2. The end surface 66 is arranged opposite to the inclined surface 61.

[0035] The mounting surface 64, the third stepped surface 23, the right end surface of the annular support 8, and the first sealing surface 65 form a containing cavity 10 for temporarily storing the medium, wherein the annular support 8 is arranged to support and limit the first sealing ring 83 and the second sealing ring 84, so as to limit the first sealing ring 83 and the second sealing ring 84 on the inner and outer walls of the annular support 8, so that the first sealing ring 83 and the second sealing ring 84 can play a sealing role, and the medium can be prevented from flowing from the containing cavity 10 into the first gap or flowing from the first gap into the containing cavity 10, and the annular support 8 can support and limit the first sealing ring 83 and the second sealing ring 84, so as to prevent the first sealing ring 83 and the second sealing ring 84 from deforming and affecting the sealing between the valve seat 6 and the hemisphere 3, and the annular support 8 can make the structure of the entire ball valve more stable and the sealing effect better.

[0036] The first matching surface 63 and the third stepped surface 23 are provided with a second gap for the medium to flow into or out of the containing cavity 10.

[0037] The mounting surface 64 is provided with a mounting groove 641 for mounting the elastic member 9, one end of the elastic member 9 extends into the mounting groove 641, and the other end is arranged on the right end surface of the annular support 8.

[0038] In this embodiment, the medium is a conventional non-crystalline medium, such as water, which does not cause elastic failure of the elastic member 9, and the elastic member 9 can be a spring.

[0039] In other embodiments, if the medium is a liquid that is easy to crystallize or corrosive, the elastic member 9 can be a covered spring, which includes an outer wear-resistant and corrosion-resistant sealing layer and an inner corrosion-resistant alloy spring. The alloy spring is covered with the sealing layer to prevent corrosive medium from entering the spring cavity and causing spring failure, which can cause leakage in the sealing surface of the ball valve.

[0040] The first sealing surface 65 is in contact with the inner ring of the annular support 8, and the first sealing ring 81 is used to realize the gap sealing between the first sealing surface 65 and the inner ring of the annular support 8.

[0041] The end of the first sealing surface 65 cooperates with the first stepped surface 21, and the first sealing surface 65 and the first stepped surface 21 are provided with a third gap for the medium to flow through, and the third gap is arranged to facilitate the medium to flow into the first gap through the third gap.

[0042] The inclined surface 61 includes an outwardly convex conforming surface 611 at its upper end that conforms to the outer wall of the hemisphere 3 to achieve a seal, and an inwardly concave surface 612 at its lower end that forms a fourth gap with the hemisphere 3. The valve seat 6 is made of rigid metal. When the valve seat 6 contacts the hemisphere 3 to achieve a seal, the seal is achieved by the compression between the outwardly convex conforming surface 611 and the hemisphere 3. During the compression sealing between the outwardly convex conforming surface 611 and the hemisphere 3, the fourth gap becomes smaller and smaller, but it does not disappear. That is, the inwardly concave surface 612 does not achieve a seal with the hemisphere 3, and there will still be a gap between the inwardly concave surface 612 and the hemisphere 3. In this embodiment, the inwardly concave surface 612 is located above the first sealing surface 65.

[0043] Since this solution uses a hemisphere 3, when the valve stem 4 drives the hemisphere 3 to rotate to achieve the opening or closing action, in order to prevent the valve seat 6 from detaching from the hemisphere 3, the valve cap 2 is provided with a limiting plate 7 on the side facing the hemisphere 3 to restrict the valve seat 6 from detaching from the hemisphere 3. The limiting plate 7 is set on the fourth step surface 24 by screws 20, and the lower end of the limiting plate 7 extends into the right side of the limiting surface 62, which can restrict the valve seat 6 from moving to the right and detaching from the hemisphere.

[0044] like Figure 3 As shown, when the medium is set to the first flow direction, that is, the medium flows from left to right, upstream of the medium, the medium will flow from the end face 66 and through the tail of the first sealing surface 65 into the first gap at the second step surface 22. The sealing of the first sealing ring 83 and the second sealing ring 84 will restrict the medium from flowing into the cavity 10. At this time, the contact area between the medium and the valve seat 6 upstream of the medium is S1. Therefore, there will be a first medium pressure F1 upstream of the medium, which will cause the valve seat 6 to move closer to the hemisphere 3. Downstream of the medium, the medium will flow into the concave surface 612. At this time, the contact area between the medium and the valve seat 6 downstream of the medium is S2. There will be a first medium back thrust F2 downstream of the medium, which will cause the valve seat 6 to move away from the hemisphere 3. As shown in the figure, the contact area S1 of the medium upstream is greater than the contact area S2 of the medium downstream, and S1-S2 = area difference S1. Since the pressure P inside the entire ball valve is fixed, according to the formula F = pressure P × area S, the first medium pressure F1 upstream is greater than the first medium counter-thrust F2 downstream. Therefore, the total force is the pressure at the upstream inlet end of the medium that pushes the valve seat 6 and the spherical surface of the hemisphere 3 to achieve a tight seal. The total force to achieve a tight seal is: medium pressure F1 + preload of the elastic element - first medium counter-thrust F2.

[0045] like Figure 4As shown, when the medium is set to the second flow direction, i.e. the medium flows from the right side to the left side, when the medium is upstream, the medium flows into the limiting surface 62, at this time, the area of the medium in contact with the valve seat 6 upstream is S4, thus, the second medium pressure F4 upstream exists to push the valve seat 6 away from the hemisphere 3; when the medium is downstream, the medium flows from the second gap at the first matching surface 63 into the accommodating cavity 10, the sealing of the first sealing ring 83 and the second sealing ring 84 limits the medium from flowing out of the accommodating cavity 10 into the first gap, at this time, the area of the medium in contact with the valve seat 6 downstream is S3, the second medium counterforce F3 downstream exists to push the valve seat 6 close to the hemisphere 3. As shown, the area S3 of the medium in contact downstream is greater than the area S4 of the medium in contact upstream, and S3-S4=S2, since the pressure P inside the entire ball valve is fixed, according to the formula F=pressure P*area S, the second medium counterforce F3 downstream is greater than the second medium pressure F4 upstream, thus, the total force is the medium pressure at the outlet end downstream pushing the valve seat 6 and the spherical surface of the hemisphere 3 to realize the tight sealing, wherein the total force realizing the tight sealing=the second medium counterforce F3+the pre-tightening force of the elastic member-the second medium pressure F4.

[0046] Therefore, whether it is the first flow direction of the medium as shown in Figure 3 or the second flow direction of the medium as shown in Figure 4 , during the bidirectional flow of the medium, bidirectional sealing can be realized, in addition to the pre-tightening force of the elastic member provided to the valve seat 6, the medium pressure difference on both sides of the valve seat 6 also provides the pressure-tightening force of the hemisphere 3 to the valve seat 6, and the medium pressure difference from one side of the valve seat 6 to the pressure-tightening hemisphere 3, the medium pressure difference can be used to realize the pressure-tightening of the hemisphere 3 to the valve seat 6 to assist in realizing the tight sealing between the valve seat 6 and the hemisphere 3, thus, the elastic member 9 does not need to be set to high elasticity, the elasticity of the elastic member 9 can be appropriately reduced, after reducing the pre-tightening force of the elastic member 9, the extrusion between the valve seat 6 and the hemisphere 3 can be reduced, the friction between the valve seat 6 and the hemisphere 3 will be smaller, the torque required to open the ball valve can be reduced, the problem of internal leakage due to the wear of the contact surface between the valve seat 6 and the hemisphere 3 can be solved, and the service life of the ball valve can be improved.

[0047] The above only describes some embodiments of the present application. Those skilled in the art can make some modifications and improvements without departing from the inventive concept, which are all within the protection scope of the present application.

Claims

1. A single seat, bi-directional sealing, eccentric half-ball valve characterized by: The valve comprises a valve body, valve caps installed on opposite sides of the valve body, and a hemispherical body installed inside the valve body, a valve seat for realizing gap sealing is arranged between the hemispherical body and the valve cap, the valve cap, the valve seat, the hemispherical body and the inner cavity of the valve body jointly form a medium flow channel, the valve cap is provided with a limiting plate on the side facing the hemispherical body to limit the valve seat from separating from the hemispherical body, an annular support is arranged on the tail of the valve seat and cooperates with the inner wall of the valve cap, a first annular accommodating cavity is arranged on the inner wall of the annular support, a second annular accommodating cavity is arranged on the outer wall of the annular support, a first sealing ring is arranged in the first annular accommodating cavity to realize gap sealing between the annular support and the valve seat, a second sealing ring is arranged in the second annular accommodating cavity to realize gap sealing between the annular support and the valve cap, and an elastic member is arranged between the annular support and the valve seat to provide pre-tightening force for the valve seat.

2. A single seat bi-directional sealing eccentrically acting half globe valve as claimed in claim 1, characterized in that: The valve cap is provided with a multi-stage stepped surface structure at the position in contact with the valve seat, the multi-stage stepped surface structure comprises a first stepped surface at the left end, a second stepped surface vertically extending upwards from the right end of the first stepped surface, a third stepped surface horizontally extending rightwards from the upper end of the second stepped surface, and a fourth stepped surface vertically extending upwards from the right end of the third stepped surface.

3. A single seat bi-directional sealing eccentrically acting half globe valve as claimed in claim 2, characterized in that: The second stepped surface is provided with a first gap for medium flow at the left end surface of the annular support, the third stepped surface is in contact with the outer circle of the annular support, and the second sealing ring is used to realize gap sealing between the third stepped surface and the outer circle of the annular support.

4. A single seat bi-directional sealing eccentrically acting half- globe valve according to claim 2, characterized in that: The valve seat comprises an inclined surface facing the hemispherical body, a limiting surface extending upwards from the upper end of the inclined surface and in contact with the limiting plate, a first matching surface horizontally extending leftwards from the left end of the limiting surface and matching with the third stepped surface, a mounting surface extending downwards from the left end of the first matching surface and facing the annular support, a first sealing surface horizontally extending leftwards from the lower end of the mounting surface and in contact with the outer circle of the annular support, and an end surface vertically extending downwards from the left end of the first sealing surface and facing the valve cap, the end surface is arranged opposite to the inclined surface.

5. A single seat bi-directional sealing eccentric half- globe valve as defined in claim 4, characterized in that: The mounting surface, the third stepped surface, the right end surface of the annular support and the first sealing surface form a containing cavity for temporarily storing medium.

6. A single seat bi-directional sealing eccentric half- globe valve as claimed in claim 4, wherein: The first matching surface and the third stepped surface are provided with a second gap for medium to flow into or out of the containing cavity.

7. A single seat bi-directional sealing eccentric half- globe valve as claimed in claim 4, wherein: The mounting surface is provided with a mounting groove for mounting the elastic member, one end of the elastic member extends into the mounting groove, and the other end is arranged at the right end surface of the annular support.

8. A single seat bi-directional sealing eccentric half- globe valve as claimed in claim 4, wherein: The first sealing ring is used to realize gap sealing between the first sealing surface and the inner circle of the annular support, the end of the first sealing surface matches with the first stepped surface, and a third gap for medium flow is arranged between the first sealing surface and the first stepped surface.

9. A single seat bi-directional sealing eccentric half- globe valve as defined in claim 4 wherein: The inclined surface comprises an outer convex profiling surface in contact with the outer wall of the hemispherical body at the upper end to realize sealing, and an inner concave surface between the lower end and the hemispherical body to form a fourth gap.

10. A single seat bi-directional sealing eccentric half- globe valve as claimed in claim 4, wherein: The limiting plate is arranged on the fourth step surface by a screw, and the lower end of the limiting plate extends into the right side of the limiting surface.

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