A pressure-balanced low-torque sealing ball valve

Abstract

The closure of the valve body is fixed with the closure of the valve body, and the closure of the valve body is fixed with the closure of the valve body to form a circle, and the closure of the valve body is fixed with the closure of the valve body to form a circle.

Description

Technical Field

[0001] The present invention relates to the technical field of process industry automatic control devices, and in particular to a pressure-balanced low-torque sealing ball valve. Background Art

[0002] Traditional ball valves operate with a quarter-turn shaft, typically rotating between 0 and 90 degrees. These valves require packing seals. Under high temperatures and pressures, or when the medium is a highly permeable, flammable, or explosive gas, micro-leakage can occur during the valve stem rotation, leading to fires and explosions. In particular, leakage of radioactive fluids in nuclear power primary circuits poses significant risks to the environment and health.

[0003] On the other hand, traditional ball valves have very high opening and closing torques due to the pressure differential across the valve. This leads to significant wear between the ball and seat, and between the shaft and bearings. This wear is particularly pronounced under high temperature, high pressure, and media containing solid particles, resulting in a very short valve lifespan. Furthermore, high-pressure ball valves require very large actuators, which are 4-6 times the size of the valve body. This hinders on-site process layout design and significantly increases manufacturing costs.

[0004] Chinese patent CN102985731B discloses a ball valve, which reduces the torque when opening and closing the valve, but is still an angular stroke valve and still has micro-leakage at the packing seal.

[0005] Therefore, how to provide a pressure-balanced low-torque sealing ball valve is a problem that those skilled in the art urgently need to solve. Summary of the Invention

[0006] In view of this, the present invention provides a pressure-balanced low-torque sealing ball valve, which changes the angular stroke driving mode of the traditional ball valve and has a simple structure, easy use, good sealing effect and long service life.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: a pressure-balanced low-torque sealing ball valve, comprising:

[0008] A valve body, wherein the top of the valve body is connected to a first valve cover, a mounting hole is provided in the middle of the first valve cover, the top of the first valve cover is sealingly connected to a second valve cover, a valve stem hole is provided on the second valve cover, a balancing hole is provided in communication with the first and second valve covers, the balancing hole is communicated with the valve stem hole, and a guide hole is provided on the downstream side wall of the valve body to communicate with the balancing hole;

[0009] A valve stem, the valve stem being axially slidably connected in an up-and-down direction in the valve stem hole, with one end of the valve stem extending out of a second valve cover, a sealing ring for sealing a balancing hole being fixedly connected to the middle portion of an outer side wall of the valve stem; a guide arc groove being provided on the outer side wall of the other end of the valve stem, a pin being slidably connected in the guide arc groove, a flow hole being provided on the other end surface of the valve stem, the flow hole extending to the outer side wall of the valve stem and communicating with the valve stem hole;

[0010] A transmission sleeve is rotatably positioned in the mounting hole, a pin hole for engaging a pin rod is provided on a side wall of the transmission sleeve, and the axial movement of the valve stem causes the transmission sleeve to rotate circumferentially;

[0011] A ball core, the ball core is rotatably located inside the valve body and fixedly connected to the end of the transmission sleeve, a ball cap mounting groove is provided on one side of the ball core, a ball cap is slidably connected in the ball cap mounting groove, the ball cap and the ball cap mounting groove cooperate to form a back pressure cavity, and a channel connecting the back pressure cavity and the flow hole is provided on the ball core;

[0012] The valve seat is the downstream valve seat and is installed inside the valve body. The ball crown abuts and seals the valve seat. When the valve is open, the pressure in the back pressure chamber is the same as the pressure in the pipeline before and after the valve. When the valve is closed, the pressure in the back pressure chamber is the same as the pressure in the pipeline before the valve and is greater than the pressure in the pipeline after the valve.

[0013] The beneficial effects of the present invention are as follows: the guide arc groove on the valve stem cooperates with the transmission sleeve through the pin rod. When the valve stem moves axially up and down, it drives the transmission sleeve to rotate, thereby driving the ball core to complete the valve opening and closing action. The traditional angular stroke drive mode is changed to a linear stroke drive mode, which better avoids the problem of micro-leakage between the valve stem and the valve cover. At the same time, due to the design of the back pressure chamber, after the valve is closed, the pressure in the back pressure chamber is the same as the pressure in the pipeline in front of the valve and greater than the pressure in the pipeline behind the valve. There is a pressure difference that can better achieve the sealing between the ball crown and the valve seat. The pressure in the back pressure chamber changes with the valve opening and closing state. When the valve is opened, the sealing ring releases the blocking state of the balance hole, and the back pressure chamber is connected to the pipeline behind the valve through the balance hole to achieve pressure balance. At the same time, the pressure in the pipeline in front of the valve is relatively high, which will force the ball crown away from the valve seat, making it easier to open the valve. The present invention has a good sealing effect and avoids leakage. Since the friction between the ball crown and the valve seat during the opening and closing process is small, the service life of the valve seat can be extended, thereby reducing construction and operating costs.

[0014] Preferably, the second valve cover is connected to a perforated pressure cover at the top of the valve stem hole, one end of the valve stem extends out of the perforated pressure cover, a bellows is provided on the outside of the valve stem, one end of the bellows is sealed to the perforated pressure cover, and the other end of the bellows is sealed to the middle step of the valve stem.

[0015] The resulting technical effect is: the axial movement of the valve stem can be driven by the actuator, and the provided bellows can expand and contract as the valve stem moves up and down, isolating the connection between the valve stem hole and the external space, achieving a static sealing effect, and preventing the medium from leaking from the gap between the valve stem and the perforated gland.

[0016] Preferably, the valve stem includes a connecting section and a driving section that are integrally connected, the connecting section corresponds to one end of the valve stem, and the driving section corresponds to the other end of the valve stem, the sealing ring is fixedly connected to the outer side wall of one end of the driving section close to the connecting section, the guide arc groove is opened on the outer side wall of the driving section, one end of the flow hole extends to the end face of the driving section, and the other end extends to the outer side wall of the driving section.

[0017] The resulting technical effect is: since the driving section is provided with a guide arc groove, the guide arc groove causes the transmission sleeve to rotate circumferentially through the pin rod to complete the opening and closing state of the valve. The sealing ring is a key component for conducting the back pressure chamber and the pipeline behind the valve. After the sealing ring blocks the balancing hole, it isolates the connection between the back pressure chamber and the pipeline behind the valve. The balancing hole can be opened to realize the connection between the back pressure chamber and the pipeline behind the valve. The flow hole is used as a flow channel to ensure the conduction relationship between the back pressure chamber and the balancing hole.

[0018] Preferably, a sealing cone surface is provided on the sealing ring, a sealing inclined surface is provided on the inner wall of the valve stem hole, one end of the balancing hole extends to the sealing inclined surface, the sealing cone surface abuts and cooperates with the sealing inclined surface to seal the balancing hole, and a pressure-stabilizing hole is provided on the side wall of the sealing ring. When the balancing hole is blocked, the back pressure cavity is connected to the valve stem hole through the channel, the flow hole and the pressure-stabilizing hole.

[0019] The resulting technical effect is that the sealing ring seals the balancing hole through the sealing cone surface, achieving high-quality sealing. The pressure-stabilizing hole can balance the back pressure chamber pressure with the external pressure of the bellows, reducing the unbalanced force of the valve stem. The outer circumference of the sealing ring does not seal against the inner wall of the valve stem hole.

[0020] Preferably, there are two groups of guide arc grooves and they are rotationally symmetrically opened on the outer wall of the driving section. The guide arc grooves include two straight segments and one curved segment. The two straight segments correspond to the axial direction of the driving section. The two straight segments are distributed 90 degrees apart in the circumferential direction and have a spacing distance in the axial direction. The two ends of the curved segment are respectively connected to the two straight segments.

[0021] The resulting technical effect is: the guide arc groove moves axially with the valve stem, so due to the design of the curved segment, the valve stem can cause the transmission sleeve to rotate circumferentially, and the circumferential rotation angle is the circumferential interval between the two straight segments, that is, 90 degrees. In addition, when the valve is closed, the straight segment can rotate the ball core to the closed position. At this time, the valve stem continues to move downward, and the sealing ring on the valve stem can apply a sealing force to the sealing surface on the second valve cover to close the balance hole. The pressure connection between the pipeline behind the valve and the back pressure chamber is cut off. When opening the valve, the valve stem first moves upward to connect the pressure between the back pressure chamber and the rear of the valve, and then the ball core rotates to open under the action of the guide arc groove, reducing the torque when opening the valve and avoiding excessive friction loss between the ball crown and the valve seat.

[0022] Preferably, a keyway is provided above the guide arc groove corresponding to the driving section, an anti-rotation key is connected in the keyway, a sliding groove is provided on the hole wall of the valve stem hole and corresponding to its axial direction, and the anti-rotation key is slidably connected in the sliding groove.

[0023] The resulting technical effect is that the key block ensures that the valve stem does not rotate circumferentially during axial movement, and also ensures the axial movement accuracy of the valve stem.

[0024] Preferably, a first ring groove is provided on the outer side of the top of the ball core, a first metal piston ring is provided in the first ring groove, and the first metal piston ring abuts against the inner wall of the first valve cover; the spherical crown has a circumferential surface, a second ring groove is provided on the circumferential surface, a second metal piston ring is connected to the second ring groove, and the outer side wall of the second metal piston ring abuts against the groove wall of the spherical crown mounting groove.

[0025] The resulting technical effect is: the sealing level of the first metal piston ring and the second metal piston ring is low, only level IV, and cannot completely cut off the seal. Since the pipeline in front of the valve and the back pressure chamber are isolated by the metal piston ring, the pressure in the back pressure chamber and the pipeline in front of the valve will gradually balance. At this time, there is a pressure difference on both sides of the ball crown, and the pressure pushes the ball crown and the valve seat to achieve sealing, and the upstream and downstream of the valve are cut off.

[0026] Preferably, a boss is provided in the middle of the bottom of the spherical crown installation groove, and a recess matching the boss is provided on the end surface of the spherical crown. The boss is slidably connected to the recess and guides the movement of the spherical crown.

[0027] The resulting technical effect is that the cooperation between the convex column and the sink groove realizes the stable movement of the spherical crown, thereby changing the sealing state between the spherical crown and the valve seat.

[0028] Preferably, the ball core has a central channel, the caliber of the central channel is the same as the caliber of the front and rear pipelines of the valve body. When the valve is just closed, the pressure in the pipeline on the front side of the valve body is greater than the pressure in the back pressure chamber. At this time, the pressure in the back pressure chamber is equal to the pressure in the pipeline on the rear side of the valve body. After closing for a while, due to the low sealing level of the first metal piston ring and the second metal piston ring, and the sealing ring blocking the balance hole, the pressure in the back pressure chamber gradually balances with the pressure in the pipeline on the front side of the valve body. At this time, the pressure in the back pressure chamber is greater than the pressure in the pipeline on the rear side of the valve body, thereby achieving a tight seal between the ball crown and the valve seat.

[0029] The resulting technical effect is: the central channel of the ball core can connect the pipelines before and after the valve. When the valve is just closed, the pressure in the pipeline in front of the valve is greater than the pressure in the back pressure chamber, but the pressure in the back pressure chamber will gradually balance the pressure in the pipeline in front of the valve, so that there is a pressure difference between the back pressure chamber and the pipeline pressure behind the valve, thereby improving the seal.

[0030] Preferably, in the initial stage of valve opening, the valve stem drives the sealing ring to rise, the balancing hole opens, and the back pressure chamber is connected with the pipeline on the rear side of the valve body through the channel, the flow hole, and the balancing hole. At this time, the pressure in the back pressure chamber is the same as the pressure in the pipeline on the rear side of the valve body and is less than the pressure in the pipeline on the front side of the valve body, and the ball crown moves away from the valve seat and disengages from the valve seat.

[0031] The resulting technical effect is: when the valve is opened, the balancing hole opens first, and the back pressure chamber is depressurized to achieve pressure balance with the pipeline behind the valve. In this state, the sealing contact force between the ball crown and the valve seat is reduced. When the valve stem drives the transmission sleeve to rotate, the high pressure in the pipeline in front of the valve will cause the ball crown to move closer to the ball core until the pressure before and after the valve is balanced. During this process, the torque required to open the valve is extremely small, and the friction damage between the ball crown and the valve seat is also small during the valve opening process, thereby extending the service life of the components. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an overall structural diagram of a pressure-balanced low-torque sealing ball valve of the present invention;

[0033] Figure 2 This is a cross-sectional view of a pressure-balanced low-torque sealing ball valve according to the present invention;

[0034] Figure 3 This is a structural diagram of a transmission sleeve of a pressure-balanced low-torque sealing ball valve of the present invention;

[0035] Figure 4 This is a valve stem structure diagram of a pressure-balanced low-torque sealing ball valve of the present invention;

[0036] Figure 5 This is a structural diagram of a ball core of a pressure-balanced low-torque sealing ball valve of the present invention;

[0037] Figure 6This is a structural diagram of a ball crown of a pressure-balanced low-torque sealing ball valve of the present invention;

[0038] Figure 7 This is a structural diagram of a sealing ring of a pressure-balanced low-torque sealing ball valve of the present invention.

[0039] 1 valve body, 101 guide hole, 2 first valve cover, 201 mounting hole, 3 second valve cover, 301 valve stem hole, 302 perforated cover, 4 balancing hole, 5 sealing ring, 501 sealing cone, 502 pressure-stabilizing hole, 6 valve stem, 601 connecting section, 602 driving section, 6021 guide arc groove, 6022 keyway, 6023 flow hole, 7 transmission sleeve, 8 ball core, 801 ball crown mounting groove, 802 channel, 9 ball crown, 901 circumferential surface, 10 back pressure chamber, 11 bellows, 12 valve seat, 13 end bearing, 14 pin, 15 anti-rotation key. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] See the attached Figures 1 to 7 According to an embodiment of the present invention, a pressure-balanced low-torque sealing ball valve comprises:

[0042] The valve body 1 has a notch on the top. The top of the valve body 1 is connected to the first valve cover 2. The middle of the first valve cover 2 is provided with a mounting hole 201. The first valve cover does not close the valve body. The top of the first valve cover 2 is sealed and connected to the second valve cover 3. The second valve cover 3 is provided with a valve stem hole 301. The side walls of the first valve cover 2 and the second valve cover 3 are provided with a connecting balancing hole 4. The balancing holes of the first upper valve cover and the second upper valve cover are sealed with a gasket. The balancing hole 4 is connected to the valve stem hole 301. A guide hole 101 connected to the balancing hole is provided on the downstream side wall of the valve body 1, and the connection between the guide hole and the balancing hole is ensured to be sealed.

[0043] The valve stem 6 is axially slidably connected within the valve stem hole 301, with one end of the valve stem 6 extending out of the second valve cover 3. A sealing ring 5 for sealing the balancing hole is fixedly connected to the middle of the outer side wall of the valve stem 6. A guide arc groove 6021 is provided on the outer side wall of the other end of the valve stem 6, and a pin rod 14 is slidably connected within the guide arc groove 6021. A flow hole 6023 is provided on the other end surface of the valve stem 6, extending to the outer side wall of the valve stem and communicating with the valve stem hole.

[0044] The transmission sleeve 7 is a stepped cylindrical sleeve, positioned at the top and bottom by end bearings 13, allowing for rotational motion. The sleeve 7 rotates within the mounting hole 201. Two centrally symmetrical pin holes are defined on the sidewalls of the sleeve, with pins fitting within the holes. The lower portion of the sleeve is fixedly connected to the ball core with a cylindrical pin. Rotation of the sleeve drives the ball core to rotate, while axial movement of the valve stem 6 causes the sleeve 7 to rotate circumferentially.

[0045] The ball core 8 is rotatably located inside the valve body 1 and is fixedly connected to the end of the transmission sleeve. A ball crown mounting groove 801 is provided on one side of the ball core 8. A ball crown 9 is slidably connected in the ball crown mounting groove 801. The ball crown 9 cooperates with the ball crown mounting groove to form a back pressure chamber 10. A channel 802 is provided on the ball core 8 to connect the back pressure chamber and the flow hole.

[0046] The valve seat 12 is a circular ring with a spherical surface. It is fixed to the valve body. One side of the valve seat seals against the valve body. The spherical surface on the other side of the valve seat and the spherical surface of the spherical cap have the same diameter. The two contact to achieve a valve seal. Specifically, the valve seat 12 is the downstream valve seat and is installed inside the valve body. The spherical cap 9 abuts against the valve seat 12 to seal. When the valve is open, the pressure in the backpressure chamber 10 is the same as the pressure in the pipelines upstream and downstream of the valve. When the valve is closed, the pressure in the backpressure chamber 10 is the same as the pressure in the pipeline upstream of the valve and greater than the pressure in the pipeline downstream of the valve.

[0047] In other embodiments, a perforated pressure cover 302 is connected to the top of the second valve cover 3 corresponding to the valve stem hole 301, one end of the valve stem 6 extends out of the perforated pressure cover 302, and a bellows 11 is provided on the outside of the valve stem 6. One end of the bellows 11 is sealed to the perforated pressure cover 302, and the other end of the bellows 11 is sealed to the outer wall of the valve stem 6. A bellows static seal is adopted between the valve stem and the perforated pressure cover, and the bellows can expand and contract as the valve stem moves.

[0048] In other specific embodiments, the valve stem 6 includes an integrally connected connecting section 601 and a driving section 602. The connecting section 601 corresponds to one end of the valve stem 6, and the driving section 602 corresponds to the other end of the valve stem 6. The sealing ring 5 is a metal ring with a sealing cone. The sealing ring 5 is fixedly connected to the outer wall of the driving section 602 at the end closest to the connecting section 601 by an end-face retaining ring, and moves up and down with the valve stem. A guide arc groove 6021 is defined in the outer wall of the driving section 602. The flow hole 6023 extends from one end to the end surface of the driving section 602 and from the other end to the outer wall of the driving section 602. The flow hole serves as a flow passage to facilitate communication between the backpressure chamber and the valve stem hole.

[0049] In other specific embodiments, a sealing cone surface 501 is provided on the sealing ring 5, a sealing inclined surface is provided on the inner wall of the valve stem hole 301, one end of the balancing hole 4 extends to the sealing inclined surface, the sealing cone surface 501 abuts against the sealing inclined surface and blocks the balancing hole 4, and a pressure-stabilizing hole 502 is provided on the side wall of the sealing ring 5. When the balancing hole is blocked, the back pressure chamber 10 is connected to the valve stem hole 301 through the channel 802, the flow hole 6023, and the pressure-stabilizing hole 502.

[0050] In other embodiments, two sets of guide arc grooves 6021 are rotationally symmetrically arranged on the outer wall of the driving section 602. The guide arc grooves 6021 include two straight segments and one curved segment. The two straight segments correspond to the axial direction of the driving section 602. The two straight segments are circumferentially spaced 90° apart and axially spaced apart. The ends of the curved segment are connected to the two straight segments, respectively. In other words, the ends of the curved segment are circumferentially spaced 90° apart, enabling the ball core to rotate 90°. Furthermore, when the valve is closed, the ball core has already rotated to the closed position. At this time, the valve stem continues to move downward, and the sealing ring on the valve stem can apply a sealing force to the sealing surface on the second valve cover, sealing the balancing hole. It should be noted that after the balancing hole is closed, the balancing hole and the flow hole are isolated, preventing leakage. This cuts off the pressure connection between the pipeline after the valve and the back pressure chamber. When opening the valve, the valve stem first moves upward to connect the pressure between the back pressure chamber and the rear of the valve, and then the ball core rotates to open under the action of the guide arc groove, reducing the torque when opening the valve and avoiding excessive friction loss between the ball crown and the valve seat during the opening and closing process of the valve, thereby extending the service life of the components.

[0051] In some other specific embodiments, a key groove 6022 is provided above the driving section 602 corresponding to the guide arc groove 6021, and an anti-rotation key 15 is connected to the key groove 6022. A sliding groove is provided on the hole wall of the valve stem hole 301 and corresponding to its axial direction. The anti-rotation key 15 is slidably connected in the sliding groove to ensure that the valve stem only moves axially and does not rotate circumferentially.

[0052] In other embodiments, the top outer side of the spherical core 8 is provided with a first annular groove, within which a first metal piston ring is mounted, abutting the inner sidewall of the first valve cover 2. The spherical cap 9 has a circumferential surface 901 with a second annular groove formed therein. A second metal piston ring is connected therein, with the outer sidewall of the second metal piston ring abutting the wall of the spherical cap mounting groove 801. The sealing level of the metal piston ring is relatively low, providing a certain sealing effect, but not a complete seal. After a certain period of time, the pressure on both sides of the metal piston ring gradually balances (the pressure in the pipeline upstream of the valve and the pressure in the backpressure chamber balance).

[0053] In some other embodiments, a boss is provided in the middle of the bottom of the spherical cap mounting groove 801, and a recess is provided on the end face of the spherical cap 9 to match the boss. The boss is slidably connected to the recess and guides the movement of the spherical cap. The boss can guide the movement of the spherical cap.

[0054] In other embodiments, the ball core 8 has a central channel, and the diameter of the central channel is the same as the diameter of the front and rear pipes of the valve body. When the valve is just closed, the pressure in the pipe on the front side of the valve body is greater than the pressure in the back pressure chamber. At this time, the pressure in the back pressure chamber is equal to the pressure in the pipe on the rear side of the valve body. After being closed for a while, due to the low sealing level of the first metal piston ring and the second metal piston ring, the pressure in the back pressure chamber gradually balances with the pressure in the pipe on the front side of the valve body. At this time, the pressure in the back pressure chamber is greater than the pressure in the pipe on the rear side of the valve body, thereby achieving a tight seal between the ball crown and the valve seat.

[0055] When the valve is just opened, the valve stem 6 drives the sealing ring 5 to rise, the balancing hole 4 opens, and the back pressure chamber is connected with the pipeline on the rear side of the valve body through the flow hole 6023 and the balancing hole 4. At this time, the pressure in the back pressure chamber is the same as the pressure in the pipeline on the rear side of the valve body and is less than the pressure in the pipeline on the front side of the valve body. The ball crown 9 moves away from the valve seat 12 and separates from the valve seat.

[0056] Working principle:

[0057] The built-in transmission sleeve converts the linear motion of the valve stem into the angular motion of the ball core; the valve stem moves up and down, driving the transmission sleeve and ball core to rotate, thus realizing the opening and closing of the valve.

[0058] During valve opening and closing, the relative pressure differential between the high-pressure chamber (in the pipeline preceding the valve), the back-pressure chamber, and the low-pressure chamber (in the pipeline following the valve) causes the spherical crown to move forward and backward (relative to the ball core), sealing and releasing it from the valve seat. The valve stem drives the sealing ring to isolate and connect the back-pressure chamber and the low-pressure chamber.

[0059] Introduction to the opening and closing process:

[0060] When the valve is fully open, the pressure differential across the valve is negligible. As the valve closes, the opening gradually decreases, throttling the flow. The pressure differential between the valve and the valve increases, reaching its maximum when the valve is fully closed. During the opening and closing process, the valve balances the pressure differential across the ball crown (between the backpressure chamber and the pipe behind the valve) and uses this pressure differential to retract the ball crown, avoiding friction between the ball crown and the valve seat and reducing valve transmission force.

[0061] When the valve is opened and closed: When the valve is just closed, the pressure in the pipeline in front of the valve is greater than the pressure in the back pressure chamber and the pressure in the pipeline behind the valve. After the valve is closed for a while, the pressure in the pipeline in front of the valve is greater than the pressure in the back pressure chamber and the pressure in the pipeline behind the valve (sealed state).

[0062] When the valve is opened from closed to open, the actuator lifts the valve stem (straight section of the slide), and the valve stem drives the sealing ring to lift. At this time, the back pressure chamber is connected to the pipeline behind the valve, and the pressure in the back pressure chamber is released. The pressure in the pipeline before the valve is greater than the pressure in the back pressure chamber and equals the pressure in the pipeline behind the valve.

[0063] Since the volume of the back pressure chamber is much smaller than the cavity of the pipeline behind the valve, the back pressure chamber quickly achieves pressure balance with the pipeline behind the valve at the moment of opening, and the ball crown no longer presses the valve seat, that is, at this time the ball crown and the valve seat no longer form a sealing state (the medium in the pipeline before the valve enters the sealing interface, which will cause the ball crown to have a tendency to move closer to the ball core).

[0064] Since the force on the inside of the ball crown is smaller than the force on the outside (the inside is affected by the force of the back pressure chamber, and the outside is affected by the force of the pipeline behind the valve + the force given by the medium in the pipeline in front of the valve), the ball crown will shrink inward, and the ball crown and the valve seat will separate. After separation, the pressure difference between the pipelines before and after the valve is reduced. At this time, the torque required to rotate the ball core is extremely low.

[0065] Several pressure states are described:

[0066] When the valve ball core flow channel is parallel to the valve body flow channel (fully open): valve front pipe pressure = back pressure chamber pressure = valve back pipe pressure (ball crown is stationary)

[0067] When the valve ball core flow channel and the valve body flow channel are 45 degrees (half open): the pressure in the pipeline before the valve > the pressure in the back pressure chamber = the pressure in the pipeline after the valve (a pressure difference is generated, and the ball crown shrinks inward)

[0068] When the valve ball core flow channel is perpendicular to the valve body flow channel (at the moment of full closing and the balance hole is not cut off): the pipeline pressure before the valve > the back pressure chamber pressure = the pipeline pressure after the valve (there is a pressure difference, the ball crown shrinks inward)

[0069] When the valve ball core flow channel is perpendicular to the valve body flow channel (fully closed and the balancing hole is cut off): the pipeline pressure before the valve = the back pressure chamber pressure > the pipeline pressure after the valve (there is a pressure difference, the ball crown moves outward and presses the valve seat to achieve sealing).

[0070] As for the devices and methods of use disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the methods.

[0071] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pressure balanced low torque sealing ball valve, characterized in that: include: A valve body (1), wherein the top of the valve body (1) is connected to a first valve cover (2), a mounting hole (201) is provided in the middle of the first valve cover (2), the top of the first valve cover (2) is sealedly connected to a second valve cover (3), a valve stem hole (301) is provided on the second valve cover (3), a balancing hole (4) is provided in communication with the first valve cover (2) and the second valve cover (3), the balancing hole (4) is in communication with the valve stem hole (301), and a guide hole (101) is provided on the downstream side wall of the valve body (1); A valve stem (6), wherein the valve stem (6) is axially slidably connected in the valve stem hole (301) and one end of the valve stem (6) extends out of the second valve cover (3), and a sealing ring (5) for sealing a balancing hole is fixedly connected to the middle of the outer side wall of the valve stem (6); a guide arc groove (6021) is provided on the outer side wall of the other end of the valve stem (6), and a pin rod (14) is slidably connected in the guide arc groove (6021); a flow hole (6023) is provided on the other end surface of the valve stem (6), and the flow hole (6023) extends to the outer side wall of the valve stem and is connected to the valve stem hole; A transmission sleeve (7), the transmission sleeve (7) is rotatably positioned in the mounting hole (201), a pin hole for cooperating with a pin rod is provided on a side wall of the transmission sleeve (7), and the axial movement of the valve stem (6) causes the transmission sleeve (7) to rotate circumferentially; a ball core (8), the ball core (8) being rotatably located inside the valve body (1) and fixedly connected to the end of the transmission sleeve, a ball cap mounting groove (801) being provided on one side of the ball core (8), a ball cap (9) being slidably connected in the ball cap mounting groove (801), the ball cap (9) cooperating with the ball cap mounting groove to form a back pressure cavity (10), and a channel (802) communicating with the back pressure cavity and the flow hole being provided on the ball core (8); The valve seat (12) is a downstream valve seat and is installed inside the valve body. The ball crown (9) abuts against the valve seat (12) to form a seal. When the valve is open, the pressure of the back pressure chamber (10) is the same as the pressure of the pipeline before and after the valve. When the valve is closed, the pressure of the back pressure chamber (10) is the same as the pressure of the pipeline before the valve and is greater than the pressure of the pipeline after the valve.

2. A pressure-balanced low-torque sealing ball valve according to claim 1, characterized in that: The second valve cover (3) is connected to a perforated gland (302) at the top of the valve stem hole (301), one end of the valve stem (6) extends out of the perforated gland (302), a bellows (11) is provided on the outside of the valve stem (6), one end of the bellows (11) is sealed to the perforated gland (302), and the other end of the bellows (11) is sealed to the middle step of the valve stem (6).

3. A pressure-balanced low-torque sealing ball valve according to claim 2, characterized in that: The valve stem (6) includes a connecting section (601) and a driving section (602) that are integrally connected, the connecting section (601) corresponds to one end of the valve stem (6), and the driving section (602) corresponds to the other end of the valve stem (6), the sealing ring (5) is fixedly connected to the outer wall of one end of the driving section (602) close to the connecting section (601), the guide arc groove (6021) is opened on the outer wall of the driving section (602), and one end of the flow hole (6023) extends to the end surface of the driving section (602), and the other end extends to the outer wall of the driving section (602).

4. A pressure-balanced low-torque sealing ball valve according to claim 3, characterized in that: The sealing ring (5) is provided with a sealing cone surface (501), the inner wall of the valve stem hole (301) is provided with a sealing slope, one end of the balancing hole (4) extends to the sealing slope, the sealing cone surface (501) abuts against the sealing slope and blocks the balancing hole (4), and a pressure stabilizing hole (502) is provided on the side wall of the sealing ring (5). When the balancing hole is blocked, the back pressure chamber (10) is connected to the valve stem hole (301) through the channel (802), the flow hole (6023), and the pressure stabilizing hole (502).

5. The pressure-balanced low-torque sealing ball valve according to claim 3, characterized in that: There are two groups of guide arc grooves (6021) which are rotationally symmetrically opened on the outer wall of the driving section (602). The guide arc grooves (6021) include two straight segments and one curved segment. The two straight segments correspond to the axial direction of the driving section (602). The two straight segments are distributed at a 90° interval in the circumferential direction and have a spacing distance in the axial direction. The two ends of the curved segment are respectively connected to the two straight segments.

6. A pressure-balanced low-torque sealing ball valve according to claim 5, characterized in that: A keyway (6022) is provided above the driving section (602) corresponding to the guide arc groove (6021), and an anti-rotation key (15) is connected in the keyway (6022). A sliding groove is provided on the hole wall of the valve stem hole (301) and corresponding to its axial direction, and the anti-rotation key (15) is slidably connected in the sliding groove.

7. A pressure-balanced low-torque sealing ball valve according to claim 6, characterized in that: The top outer side of the ball core (8) is provided with a first ring groove, a first metal piston ring is provided in the first ring groove, and the first metal piston ring abuts against the inner wall of the first valve cover (2); the ball crown (9) has a circumferential surface (901), the circumferential surface (901) is provided with a second ring groove, a second metal piston ring is connected in the second ring groove, and the outer side wall of the second metal piston ring abuts against the groove wall of the ball crown mounting groove (801).

8. The pressure-balanced low-torque sealing ball valve according to claim 7, characterized in that: A convex column is provided in the middle of the bottom of the spherical crown installation groove (801), and a recessed groove matching the convex column is provided on the end surface of the spherical crown (9). The convex column is slidably connected to the recessed groove and guides the movement of the spherical crown.

9. The pressure-balanced low-torque sealing ball valve according to claim 8, characterized in that: The ball core (8) has a central channel, the diameter of the central channel is the same as the diameter of the front and rear pipelines of the valve body. When the valve is just closed, the pressure of the pipeline on the front side of the valve body is greater than the pressure of the back pressure chamber. At this time, the pressure of the back pressure chamber is equal to the pressure of the pipeline on the rear side of the valve body. After closing for a while, due to the low sealing level of the first metal piston ring and the second metal piston ring, and the sealing ring blocking the balance hole, the pressure of the back pressure chamber gradually balances with the pressure of the pipeline on the front side of the valve body. At this time, the pressure of the back pressure chamber is greater than the pressure of the pipeline on the rear side of the valve body, thereby achieving a tight seal between the ball crown and the valve seat.

10. The pressure-balanced low-torque sealing ball valve according to claim 9, characterized in that: When the valve is initially opened, the valve stem (6) drives the sealing ring (5) to rise, the balancing hole (4) opens, and the back pressure chamber is connected to the pipeline on the rear side of the valve body through the channel (802), the flow hole (6023), and the balancing hole (4). At this time, the pressure in the back pressure chamber is the same as the pressure in the pipeline on the rear side of the valve body and is less than the pressure in the pipeline on the front side of the valve body. The ball crown (9) moves away from the valve seat (12) and separates from the valve seat.

Images