Rail ball valve pneumatic actuator with two-stage hydraulic cushion function

Abstract

The present application relates to the technical field of ball valve, and discloses a track ball valve pneumatic actuator with two-stage hydraulic buffering function, which comprises a cylinder, a hydraulic buffer tank and a pipe valve piece, the cylinder is composed of a cylinder top cover, an upper cylinder body, a partition plate, a lower cylinder body and a cylinder bottom cover, first and second pistons are respectively arranged in the upper and lower cylinder bodies, the pistons are fixedly connected with piston rods, and the first piston is provided with an extended guide section for limiting radial deflection, the hydraulic buffer tank is externally mounted on the side of the cylinder, the hydraulic buffer tank is connected with the lower cylinder body and the second piston through a hydraulic pipe to form a hydraulic buffer cavity, the buffer cavity and the hydraulic buffer tank are filled with hydraulic oil, the hydraulic oil flows between the piston and the hydraulic buffer cavity during reciprocating movement of the piston, the flow of the hydraulic oil is used to limit the movement speed of the cylinder piston, a stop rod is arranged on the first piston and penetrates through the partition plate, the stop rod can control the on-off of a hydraulic oil inlet on the partition plate, and two-stage opening and closing of the valve is realized, the pneumatic actuator can stably and timely respond during operation of the ball valve, impact damage and noise of the track ball valve during rapid action can be avoided, the service life of the track ball valve is effectively guaranteed, and the response efficiency of the ball valve under working conditions is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of ball valve technology, and more specifically to a pneumatic actuator for a track ball valve with a two-stage hydraulic buffer function. Background Technology

[0002] Due to their unique structural advantages, such as frictionless switching and low opening / closing torque, orbital ball valves are increasingly widely used in industrial pipelines in petrochemical, natural gas, and other industries. Currently, most orbital ball valves are driven by pneumatic actuators, relying on compressed air to push a cylinder piston to complete the valve opening and closing.

[0003] However, in actual operation, due to the fast response speed of pneumatic actuators, when compressed air pushes the piston to switch the direction of movement during the opening and closing of the valve body, it needs to store energy, which can easily cause the valve stem and ball to generate instantaneous high-speed impact. This can cause the ball to impact and wear the sealing surface of the valve seat, and the track groove to collide and damage the guide, resulting in obvious abnormal noise and vibration. Long-term impact and vibration will aggravate the wear of valve seals and transmission pairs, shorten the service life of the valve, and affect the stability of on-site operation.

[0004] Existing buffering solutions mainly fall into three categories: The first is integrating pneumatic buffering into the cylinder's air circuit. However, pneumatic buffering is unstable, prone to trigger timeouts, and requires modification of the cylinder body, making it unsuitable for upgrading existing valves. The second is coaxially connected hydraulic buffer cylinders at the upper or lower end of the cylinder, employing a layered structure. While this achieves buffering, it significantly increases the valve's axial installation height, making it unsuitable for applications with limited pipeline installation space. The third is a full-range hydraulic damping solution, but this reduces valve opening and closing speeds, affecting operational response efficiency and making it difficult to meet the variable-speed buffering requirements of track ball valves during opening and closing. Summary of the Invention

[0005] To address the above issues and overcome the shortcomings of existing technologies, the present invention aims to provide a pneumatic actuator for a ball valve with a two-stage hydraulic buffer function. Its core technical solution is an optimized improvement upon the third full-range hydraulic damping scheme described in the background technology, employing a structure with an external hydraulic tank mounted on the side of the cylinder. Based on this, the present invention designs a buffer control structure for the valve's two-stage opening and closing. This structure avoids impact damage and noise during rapid operation of the ball valve, effectively ensuring its service life, while also guaranteeing the valve's operational response efficiency. Furthermore, its compact structure adapts to conditions with limited axial installation space, and the externally mounted hydraulic tank allows for convenient installation without altering the core internal structure of the cylinder, supporting low-cost upgrades of in-service valves.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A pneumatic actuator for a track ball valve with a two-stage hydraulic buffer function is characterized by a cylinder, a hydraulic buffer tank, and pipe fittings. The cylinder includes a cylinder top cover, an upper cylinder body, a partition, a lower cylinder body, and a cylinder bottom cover that are sequentially and sealed along the axial direction. A first piston is disposed in the upper cylinder body, and a second piston is disposed in the lower cylinder body. Both the first and second pistons are fixedly connected to a piston rod to form a double-piston linkage structure. The lower end of the piston rod passes through the cylinder bottom cover and is drivenly connected to the valve stem of the track ball valve. The hydraulic buffer tank is externally mounted and fixed to the outer wall of the cylinder.

[0008] Furthermore, the cylinder top cover has a top cover valve inlet that communicates with the interior of the upper cylinder body on its circumference, and a top cover balance vent that communicates with the interior of the upper cylinder body on its circumference. The cylinder bottom cover has a bottom cover valve inlet that communicates with the interior of the lower cylinder body on its circumference. The partition plate has a partition plate valve inlet that communicates with the interior of the upper cylinder body on its circumference, and four liquid inlets that communicate with the interior of the lower cylinder body on its circumference.

[0009] Furthermore, the upper end of the hydraulic buffer tank is connected to the top cover balance vent and the external air passage via a three-way connector, and the lower end of the hydraulic buffer tank is connected to the liquid inlet via a hydraulic pipeline. The lower surface of the partition, the inner wall of the lower cylinder, and the upper surface of the second piston together form a hydraulic buffer chamber. The hydraulic buffer chamber and the hydraulic buffer tank are filled with hydraulic oil. When the second piston reciprocates with the piston rod, the hydraulic oil can flow back and forth between the hydraulic buffer chamber and the hydraulic buffer tank. The flow damping of the hydraulic oil limits the movement speed of the second piston, thereby limiting the opening and closing speed of the track ball valve.

[0010] Furthermore, the hydraulic buffer tank is not completely filled with hydraulic oil, and a gas buffer space is reserved at the top of the tank.

[0011] Furthermore, four vertical stop cylinders are fastened to the upper surface of the partition plate by bolts. The stop cylinders are symmetrically distributed circumferentially on the upper surface of the partition plate and correspond one-to-one with the liquid inlet. An O-ring is provided at the connection between the stop cylinder and the partition plate to prevent hydraulic oil from entering the upper cylinder. The stop cylinder is connected through the first piston.

[0012] Furthermore, the stop rod cylinder is provided with a stop rod inside. The stop rod is threaded to the upper end face of the second piston and passes through the partition. The upper end of the stop rod has a flow-limiting boss with an enlarged outer diameter. The flow-limiting boss can block the liquid inlet on the partition. After the piston moves and the flow-limiting boss passes the liquid inlet, the liquid inlet opens, and the hydraulic oil can be introduced into and out of the hydraulic buffer chamber with the reciprocating motion of the piston.

[0013] Furthermore, the first piston is provided with a guide section, which extends along the piston rod axially and penetrates the partition, thereby extending the mating length between the first piston and the piston rod, effectively limiting the radial runout of the piston, and ensuring the smoothness of the piston's reciprocating motion.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. The pneumatic actuator of the present invention is equipped with a hydraulic buffer structure, and the upper end of the hydraulic buffer tank in the hydraulic buffer structure is reserved with a gas buffer space and sealed and connected to the top cover balance vent and external air source. This avoids pressure build-up or negative pressure in the tank when the oil enters or exits, ensures uniform and consistent oil flow damping, and makes the buffering process stable and controllable. This prevents the ball valve from generating vibration and abnormal noise and impact damage during rapid action, and effectively protects the service life of the track ball valve.

[0016] 2. A stop lever is installed on the second piston. During the process of the piston moving upward to open the ball valve, the flow-limiting protrusion on the stop lever gradually releases the flow restriction on the inlet, increasing the speed at which hydraulic oil exits the hydraulic buffer chamber. This allows the ball valve to open faster until it is fully open after the ball sealing surface smoothly separates from the valve seat sealing surface. When the valve is closed, the movement trajectory of the stop lever and the speed of hydraulic oil introduction are reversed. This structure can realize two-stage speed-changing buffering in the opening and closing process of the ball valve, decelerating and buffering only in the critical stroke section when the sealing pair contacts or disengages, avoiding the problem of reducing the overall opening and closing speed of the valve and affecting the operating response efficiency due to full-stroke speed limiting.

[0017] 3. The hydraulic buffer tank is externally mounted and fixed to the side of the cylinder. The compact structure can adapt to working conditions where axial installation space is limited. The side-mounted hydraulic tank is easy to install without modifying the internal core structure and air circuit configuration of the cylinder. It can be shipped with new valves or used to quickly upgrade existing valves. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the valve in the fully closed position according to the present invention;

[0019] Figure 2 This is a schematic diagram of the valve in the fully open position according to the present invention;

[0020] Figure 3 This is a schematic diagram of the partition structure of the present invention;

[0021] Figure 4 This is a schematic diagram of the first piston structure of the present invention;

[0022] Figure 5 This is a schematic diagram of the stop bar structure of the present invention;

[0023] Figure 6 This is a schematic diagram of the gas path of the present invention;

[0024] Explanation of reference numerals in the attached drawings: 1-Cylinder top cover, 1.1-Top cover valve inlet, 1.2-Top cover balance vent, 2-Upper cylinder body, 3-Baffle plate, 3.1-Liquid inlet, 3.2-Baffle plate valve inlet, 4-Lower cylinder body, 5-Cylinder bottom cover, 5.1-Bottom cover valve inlet, 6-First piston, 6.1-Guide section, 7-Second piston, 8-Piston rod, 9-Hydraulic buffer tank, 10-O-ring, 11-Stop rod barrel, 12-Stop rod, 12.1-Flow limiting boss, 13-Hydraulic buffer chamber, 14-Valve rod, 15-Ball, 16-Valve seat, 17-Filter pressure reducing valve, 18-Solenoid valve, 19-Pneumatic control valve. Detailed Implementation

[0025] To make the technical means, creative features, working mechanism, and achieved objectives and effects of the present invention easier to understand, the technical solutions and working mechanisms of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] like Figures 1 to 5 The present invention discloses a pneumatic actuator for a track ball valve with a two-stage hydraulic buffer function, characterized by a cylinder, a hydraulic buffer tank, and a valve assembly. The cylinder comprises a cylinder top cover 1, an upper cylinder body 2, a partition plate 3, a lower cylinder body 4, and a cylinder bottom cover 5, which are sequentially and sealed along the axial direction. A first piston 6 is disposed in the upper cylinder body 2, and a second piston 7 is disposed in the lower cylinder body 4. Both the first piston 6 and the second piston 7 are fixedly connected to a piston rod 8 to form a double-piston linkage structure. The lower end of the piston rod 8 extends through the cylinder bottom cover 5 and is connected to the valve stem 14 of the track ball valve. The hydraulic buffer tank 9 is externally mounted and fixed to the outer wall of the cylinder.

[0027] Furthermore, the cylinder top cover 1 has a top cover valve inlet 1.1 symmetrically opened around its circumference, which communicates with the interior of the upper cylinder body 2. At the same time, the cylinder top cover 1 has a top cover balance vent 1.2 symmetrically opened around its circumference, which communicates with the interior of the upper cylinder body 2. The cylinder bottom cover 5 has a bottom cover valve inlet 5.1 symmetrically opened around its circumference, which communicates with the interior of the lower cylinder body 4. The partition 3 has a partition valve inlet 3.2 symmetrically opened around its circumference, which communicates with the interior of the upper cylinder body 2. At the same time, the partition 3 has four liquid inlets 3.1 symmetrically opened around its circumference, which communicate with the interior of the lower cylinder body 4.

[0028] Furthermore, the upper end of the hydraulic buffer tank 9 is connected to the top cover balance vent 1.2 and the external air passage respectively through a three-way connector. The lower end of the hydraulic buffer tank 9 is connected to the liquid inlet 3.1 through a hydraulic pipeline. The lower surface of the partition 3, the inner wall of the lower cylinder 4 and the upper surface of the second piston 7 together form a hydraulic buffer chamber 13. The hydraulic buffer chamber 13 and the hydraulic buffer tank 9 are filled with hydraulic oil. When the second piston 7 moves back and forth with the piston rod, the hydraulic oil can flow back and forth between the hydraulic buffer chamber 13 and the hydraulic buffer tank 9. The flow damping of the hydraulic oil limits the movement speed of the second piston 7, thereby limiting the opening and closing speed of the track ball valve.

[0029] Furthermore, the hydraulic buffer tank 9 is not completely filled with hydraulic oil, and a gas buffer space is reserved at the top of the tank.

[0030] Furthermore, four vertical stop cylinders 11 are fastened to the upper end face of the partition plate 3 by bolts. The stop cylinders 11 are symmetrically distributed around the upper end face of the partition plate 3 and correspond one-to-one with the liquid inlet 3.1. An O-ring 10 is provided at the connection between the stop cylinder 11 and the partition plate 3 to prevent hydraulic oil from entering the upper cylinder 2. The stop cylinder 11 is connected through the first piston 6.

[0031] Furthermore, the stop rod cylinder 11 is provided with a stop rod 12 inside. The stop rod 12 is threadedly connected to the upper end face of the second piston 7 and passes through the partition 3. The upper end of the stop rod 12 has a flow-limiting boss 12.1 with an enlarged outer diameter. The flow-limiting boss 12.1 can block the liquid inlet 3.1 on the partition 3. After the piston moves and the flow-limiting boss 12.1 passes the liquid inlet 3.1, the liquid inlet 3.1 opens, and the hydraulic oil can be introduced into and out of the hydraulic buffer chamber 13 with the reciprocating motion of the piston.

[0032] Furthermore, the first piston 6 is provided with a guide section 6.1, which extends axially along the piston rod 8 and penetrates the partition plate 3, thereby extending the mating length between the first piston 6 and the piston rod 8, effectively limiting the radial runout of the piston, and ensuring the smoothness of the piston's reciprocating motion.

[0033] The following section focuses on explaining the working mechanism of this invention.

[0034] This invention relates to a pneumatic actuator adapted to a ball valve, employing a side-mounted external hydraulic buffer tank structure and featuring a two-stage hydraulic buffering function. It precisely adapts to the operating mechanism of the ball valve, providing stable driving force while regulating the impact during opening and closing. The specific working process is as follows:

[0035] When the valve is opened, compressed gas is introduced into the lower chamber of the second piston 7 in the lower cylinder 4 through the bottom cover valve inlet 5.1, pushing the second piston 7 and piston rod 8 upward, and the volume of the hydraulic buffer chamber 13 continuously decreases; at the same time, compressed gas is introduced into the lower chamber of the first piston 6 in the upper cylinder 2 through the partition valve inlet 3.2, pushing the first piston 6 and piston rod 8 upward, and the gas at the upper end of the first piston 6 in the upper cylinder 2 is discharged from the top cover valve inlet 1.1. The two pistons drive the valve to open synchronously through the piston rod 8. In the initial stage of the stroke, the flow-limiting boss 12.1 at the upper end of the stop lever 12 and the flow-limiting baffle inlet 3.1 are blocked, and the oil passage between the hydraulic buffer chamber 13 and the hydraulic buffer tank 9 is blocked. The incompressible characteristics of hydraulic oil form a starting damping to suppress the impact at the moment of piston start. In the middle and later stages of the stroke, the stop lever 12 moves upward with the second piston 7, and the upper flow-limiting boss 12.1 disengages from the inlet 3.1, and the inlet 3.1 is fully open. Hydraulic oil flows from the hydraulic buffer chamber 13 into the hydraulic buffer tank 9, and the flow resistance is reduced. At this time, the oil level in the tank rises, and the top of the hydraulic buffer tank 9 simultaneously discharges excess gas from the tank, avoiding abnormal increase in damping due to pressure buildup in the tank. The oil flow damping is kept stable throughout the stroke, ensuring that after the sealing surface of the ball 15 smoothly disengages from the sealing surface of the valve seat 16, the piston can maintain a smooth and rapid movement until the valve is fully open, ensuring opening and closing response efficiency.

[0036] When the valve is closed, compressed gas is introduced into the upper chamber of the first piston 6 in the upper cylinder 2 through the valve inlet 1.1 of the top cover, pushing the first piston 6 and piston rod 8 downward. The gas at the lower end of the first piston 6 in the upper cylinder 2 is discharged from the valve inlet 3.2 of the partition. The first piston 6 moves down synchronously with the second piston 7 through the piston rod 8. The gas at the lower end of the second piston 7 in the lower cylinder 4 is discharged from the valve inlet 5.1 of the bottom cover, driving the valve to close. During the initial and middle stages of the stroke, the inlet 3.1 remains fully open, and hydraulic oil is replenished from the hydraulic buffer tank 9 into the gradually increasing volume of the hydraulic buffer chamber 13. At the same time, an external air source replenishes the tank with gas to prevent negative pressure from forming inside the tank, which would cause poor oil backflow and ensure that the piston descends smoothly and quickly during this stage. At the end of the stroke, the flow-limiting boss 12.1 closes the inlet 3.1 as the piston descends. At this time, the volume of hydraulic oil in the hydraulic buffer chamber 13 is fixed and cannot be replenished. As the piston continues to descend, the volume of the hydraulic buffer chamber 13 further expands, and the pressure inside the chamber continues to decrease and form a negative pressure. A pressure difference damping force opposite to the direction of movement is generated between the upper and lower end faces of the second piston 7, and the damping force continues to increase with the increase of the stroke, effectively counteracting the downward inertia and pneumatic thrust of the piston, allowing the piston to decelerate smoothly and reach its position, avoiding rigid impact and protecting the sealing pair and transmission structure.

[0037] Based on the above basic working principle, various modifications and improvements can be made to this structure. These innovative transformations based on this structure also fall within the scope of protection of this invention.

[0038] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pneumatic actuator for a ball valve with a two-stage hydraulic buffer function, characterized in that... The cylinder comprises a cylinder top cover, an upper cylinder body, a partition plate, a lower cylinder body, and a cylinder bottom cover, which are sequentially and sealed along the axial direction. A first piston is disposed in the upper cylinder body, and a second piston is disposed in the lower cylinder body. Both the first and second pistons are fixedly connected to the piston rod to form a double-piston linkage structure. The lower end of the piston rod passes through the cylinder bottom cover and is drivenly connected to the valve stem of the track ball valve. The hydraulic buffer tank is externally mounted and fixed to the outer wall of the cylinder.

2. The pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 1, characterized in that: The cylinder top cover has a top cover valve inlet that communicates with the interior of the upper cylinder body on its circumference. The cylinder top cover also has a top cover balance vent that communicates with the interior of the upper cylinder body. The cylinder bottom cover has a bottom cover valve inlet that communicates with the interior of the lower cylinder body on its circumference. The partition plate has a partition plate valve inlet that communicates with the interior of the upper cylinder body on its circumference. The partition plate also has four liquid inlets that communicate with the interior of the lower cylinder body on its circumference.

3. The pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 1, characterized in that: The upper end of the hydraulic buffer tank is connected to the top cover balance vent and the external air passage via a three-way connector. The lower end of the hydraulic buffer tank is connected to the liquid inlet via a hydraulic pipeline. The lower surface of the partition, the inner wall of the lower cylinder, and the upper surface of the second piston together form a hydraulic buffer chamber. The hydraulic buffer chamber and the hydraulic buffer tank are filled with hydraulic oil. When the second piston reciprocates with the piston rod, the hydraulic oil can flow back and forth between the hydraulic buffer chamber and the hydraulic buffer tank. The flow damping of the hydraulic oil limits the movement speed of the second piston, thereby limiting the opening and closing speed of the track ball valve.

4. A pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 1, characterized in that: The hydraulic buffer tank is not completely filled with hydraulic oil, and a gas buffer space is reserved at the top of the tank.

5. A pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 1, characterized in that: The upper end face of the partition plate is fastened with four vertical stop cylinders by bolts. The stop cylinders are symmetrically distributed around the upper end face of the partition plate and correspond one-to-one with the liquid inlet. An O-ring is provided at the connection between the stop cylinder and the partition plate to prevent hydraulic oil from entering the upper cylinder. The stop cylinder is connected through the first piston.

6. A pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 5, characterized in that: The stop rod cylinder is equipped with a stop rod inside. The stop rod is threaded to the upper end face of the second piston and passes through the partition. The upper end of the stop rod has a flow-limiting boss with an enlarged outer diameter. The flow-limiting boss can block the liquid inlet on the partition. After the piston moves and the flow-limiting boss passes the liquid inlet, the liquid inlet opens, and the hydraulic oil can be introduced into and out of the hydraulic buffer chamber with the reciprocating motion of the piston.

7. A pneumatic actuator for a ball valve with a two-stage hydraulic buffer function according to claim 1, characterized in that: The first piston is provided with a guide section, which extends along the piston rod axially and passes through the partition, thereby extending the mating length between the first piston and the piston rod, effectively limiting the radial runout of the piston, and ensuring the smoothness of the piston's reciprocating motion.

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