Pneumatic piston stop valve

Abstract

The present invention relates to a pneumatic piston stop valve, comprising a valve body and a valve core, wherein a horizontal valve seat is arranged in a valve cavity between an inlet and outlet passage of the valve body; the valve cavity is characterized in that an upper piston cylinder and a lower piston cylinder concentric with the valve seat are respectively formed on the upper and lower sides of the valve cavity, the valve core adopts an upper piston and a lower piston to form a double piston structure, the upper piston and the lower piston are fixedly connected to each other by a connecting rod, the annular area between the lower end face of the upper piston and the connecting rod is larger than the annular area between the upper end face of the lower piston and the connecting rod; an air pressure joint is arranged on the upper cover at the upper end of the upper piston cylinder; a sealing ring is embedded in the outer cylindrical surface of the lower part of the upper piston, the sealing ring is pressed and installed on the annular step of the upper piston by a guide ring, the outer cylindrical surface of the guide ring is dynamically sealed with the inner wall of the valve seat through hole, the diameter of the sealing ring is larger than the diameter of the guide ring, and an annular sealing surface is formed in the lower plane thereof to cooperate with the sealing surface on the outlet side of the valve seat. The valve has the advantages of small size, low manufacturing cost, reliable sealing performance, etc.

Description

Technical Field

[0001] The present invention belongs to the field of valves, and in particular relates to a piston stop valve, which is suitable for working conditions involving toxic, harmful and other dangerous media. Background Art

[0002] The structure of a pneumatic stop valve generally includes a valve body, a valve seat, a valve core, a valve stem, a valve cover, a bracket, and a pneumatic actuator. The valve core is connected to the lower end of the valve stem, and the upper end of the valve stem passes through the upper end surface of the valve cover and is connected to the valve stem nut fixedly installed on the bracket. The pneumatic actuator drives the valve stem nut to rotate, and the transmission valve stem moves up and down to realize the opening and closing operation of the valve core. One of its disadvantages is that the bracket and pneumatic actuator are installed on the upper end of the valve cover, which is large in size and high in cost; the second disadvantage is that the sealing packing between the valve stem and the valve cover is easily worn by the valve stem and leaks, and the sealing reliability is poor. Summary of the invention

[0003] The present invention aims at the disadvantages of the prior art and provides a pneumatic piston stop valve with small volume, low cost and reliable sealing performance.

[0004] The technical solution for realizing the present invention comprises a valve body and a valve core, and a horizontal valve seat is arranged in a valve cavity between the inlet and outlet channels of the valve body; the feature is that an upper piston cylinder and a lower piston cylinder concentric with the valve seat are respectively formed on the upper and lower sides of the valve cavity, the valve core adopts an upper piston and a lower piston to form a double piston structure, the outer cylindrical surface of the upper piston is dynamically sealed with the inner wall of the upper piston cylinder, the outer cylindrical surface of the lower piston is dynamically sealed with the inner wall of the lower piston cylinder, the center of the lower end surface of the upper piston and the center of the upper end surface of the lower piston are fixedly connected to each other by a connecting rod, and the annular area between the lower end surface of the upper piston and the connecting rod is larger than the annular area between the upper end surface of the lower piston and the connecting rod; An upper cover is installed on the upper end of the upper piston cylinder, and an air pressure joint is provided at the center of the upper cover plane, which is connected to the piston cavity on the lower end surface of the upper cover; a sealing ring is embedded in the outer cylindrical surface of the lower part of the upper piston, and the sealing ring is pressed and installed on the annular step of the upper piston by a guide ring, and the outer cylindrical surface of the guide ring is dynamically sealed with the inner wall of the valve seat through hole, and the diameter of the sealing ring is larger than the diameter of the guide ring. An annular sealing surface that cooperates with the sealing surface on the outlet side of the valve seat is formed in the lower plane of the sealing ring outside the guide ring, and the annular sealing surface is located on the upper side of the lower end surface of the upper piston, and an annular pressure chamber with an opening facing downward is formed between the inner wall of the guide ring and the lower end surface of the upper piston.

[0005] Preferably, the outer circumferential surface of the upper piston is provided with a first sealing ring and a second sealing ring which cooperate with the upper piston cylinder in dynamic sealing, and the outer circumferential surface of the lower piston is provided with a third sealing ring and a fourth sealing ring which cooperate with the lower piston cylinder in dynamic sealing.

[0006] Preferably, a spring is installed between the lower end surface of the lower piston and the bottom surface of the lower piston cylinder.

[0007] Preferably, a plurality of ∩-shaped windows are evenly formed in the circumferential direction of the lower ring surface of the guide ring.

[0008] Compared with the prior art, the invention has the following beneficial effects: the valve core is directly driven to close by air pressure and the valve core is automatically driven to open by medium pressure, the product has a small volume, low manufacturing cost and reliable sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the closed state of the present invention.

[0010] Figure 2 It is a structural schematic diagram of the present invention in a fully open state.

[0011] 1 valve body, 2 lower piston, 3 connecting rod, 4 guide ring, 5 sealing ring, 6 first sealing ring, 7 upper piston, 8 second sealing ring, 9 upper cover, 10 air pressure joint, 11 third sealing ring, 12 and fourth sealing ring, 13 spring, 14 lower piston cylinder. DETAILED DESCRIPTION

[0012] like Figure 1 , Figure 2The pneumatic piston stop valve shown in the figure comprises a valve body 1 and a valve core, and a horizontal valve seat is arranged in the valve cavity between the inlet and outlet channels of the valve body 1; the characteristics are as follows: an upper piston cylinder and a lower piston cylinder 14 concentric with the valve seat are respectively formed on the upper and lower sides of the valve cavity, the valve core adopts an upper piston 7 and a lower piston 2 to form a double piston structure, the outer cylindrical surface of the upper piston 7 is dynamically sealed with the inner wall of the upper piston cylinder, the outer cylindrical surface of the lower piston 2 is dynamically sealed with the inner wall of the lower piston cylinder 14, the center of the lower end surface of the upper piston 7 and the center of the upper end surface of the lower piston 2 are fixedly connected to each other by a connecting rod 3, and the upper piston 7 and the upper piston cylinder, the lower piston 2 and the lower piston cylinder 14 form a double-guiding and double-positioning structure to ensure the concentricity between the valve core and the valve seat and improve the sealing performance. The annular area between the lower end surface of the upper piston 7 and the connecting rod 3 is larger than the annular area between the upper end surface of the lower piston 2 and the connecting rod 3, so that the upward thrust of the medium in the inlet channel of the valve body 1 on the upper piston 7 is greater than the downward thrust on the lower piston 2. When there is no external force, the medium pushes the valve core upward; the upper end of the upper piston cylinder is installed with an upper cover 9, and the center of the plane of the upper cover 9 is provided with a pneumatic joint 10. The air pressure joint 10 is connected with the piston cavity at the lower end surface of the upper cover 9. When the piston cavity is injected with air pressure, the valve core is pushed down to seal with the valve seat. A sealing ring 5 is embedded in the outer cylindrical surface of the lower part of the upper piston 7. The sealing ring 5 is pressed and installed on the annular step of the upper piston 7 by the guide ring 4. The outer cylindrical surface of the guide ring 4 is dynamically sealed with the inner wall of the valve seat through hole to form a first sealing pair. The diameter of the sealing ring 5 is larger than the diameter of the guide ring 4. An annular sealing surface that cooperates with the sealing surface on the outlet side of the valve seat is formed in the lower plane of the sealing ring 5 outside the guide ring 4 to form a second sealing pair. The sealing pair realizes secondary sealing for the medium leaking from the first sealing pair. Since the medium leaking from the first sealing pair is a trace of ultra-low pressure medium, the second sealing pair can easily completely block it to achieve zero leakage. The annular sealing surface of the sealing ring 5 is located on the upper side of the lower end surface of the upper piston 7. When the valve core is opened, the lower end surface of the upper piston 7 blocks the scouring of the sealing ring 5 by the medium, improving the sealing performance. The inner wall of the guide ring 4 and the lower end surface of the upper piston 7 form an annular pressure chamber with an opening facing downward, which increases the opening height of the valve core and ensures that the valve core is fully opened. A breathing hole is provided at the bottom of the lower piston cylinder 14.

[0013] The outer circumference of the upper piston 7 is provided with a first sealing ring 6 and a second sealing ring 8 which cooperate with the upper piston cylinder for dynamic sealing. When the valve core is fully open, the first sealing ring 6 and the second sealing ring 8 form a double sealing pair with the upper piston cylinder to achieve zero leakage in the middle cavity; the outer circumference of the lower piston 2 is provided with a third sealing ring 11 and a fourth sealing ring 12 which cooperate with the lower piston cylinder 14 for dynamic sealing to achieve zero leakage in the lower cavity of the valve body 1.

[0014] A spring 13 is installed between the lower end surface of the lower piston 2 and the bottom surface of the lower piston cylinder 14. The spring 13 and the medium pressure of the inlet channel of the valve body 1 jointly push the valve core upward to reduce the valve opening pressure.

[0015] There are several ∩-shaped windows evenly formed on the circumferential direction of the lower ring surface of the guide ring 4. When the flow rate is low, the medium passes between the ∩-shaped window and the valve seat. The lower outer surface of the guide ring 4 cooperates with the inner wall of the valve seat through hole to improve the stability of the valve core when the valve core is slightly opened.

Claims

1. A pneumatic piston stop valve, comprising a valve body (1) and a valve core, wherein a horizontal valve seat is arranged in a valve cavity between an inlet and outlet passage of the valve body (1); wherein: An upper piston cylinder and a lower piston cylinder (14) are respectively provided on the upper and lower sides of the valve cavity, and are concentric with the valve seat. The valve core is composed of an upper piston (7) and a lower piston (2) to form a double piston structure. The outer cylindrical surface of the upper piston (7) is dynamically sealed with the inner wall of the upper piston cylinder. The outer cylindrical surface of the lower piston (2) is dynamically sealed with the inner wall of the lower piston cylinder (14). The center of the lower end surface of the upper piston (7) and the center of the upper end surface of the lower piston (2) are fixedly connected to each other by a connecting rod (3). The annular area between the lower end surface of the upper piston (7) and the connecting rod (3) is larger than the annular area between the upper end surface of the lower piston (2) and the connecting rod (3). An upper cover (9) is installed at the upper end of the upper piston cylinder. A pneumatic joint (10) is provided at the center of the plane of the upper cover (9). ), the air pressure joint (10) is communicated with the piston cavity at the lower end surface of the upper cover (9); a sealing ring (5) is embedded in the outer cylindrical surface of the lower part of the upper piston (7), and the sealing ring (5) is pressed and installed on the annular step of the upper piston (7) by the guide ring (4). The outer cylindrical surface of the guide ring (4) is dynamically sealed with the inner wall of the valve seat through hole. The diameter of the sealing ring (5) is larger than the diameter of the guide ring (4). An annular sealing surface that cooperates with the sealing surface on the outlet side of the valve seat is formed in the lower plane of the sealing ring (5) outside the guide ring (4). The annular sealing surface of the sealing ring (5) is located on the upper side of the lower end surface of the upper piston (7). An annular pressure chamber with an opening facing downward is formed between the inner wall of the guide ring (4) and the lower end surface of the upper piston (7).

2. The pneumatic piston stop valve according to claim 1 is characterized in that: The outer circumference of the upper piston 7 is provided with a first sealing ring 6 and a second sealing ring 8 which cooperate with the upper piston cylinder in dynamic sealing, and the outer circumference of the lower piston 2 is provided with a third sealing ring 11 and a fourth sealing ring 12 which cooperate with the lower piston cylinder 14 in dynamic sealing.

3. The pneumatic piston stop valve according to claim 1 or 2, characterized in that: A spring (13) is installed between the lower end surface of the lower piston (2) and the bottom surface of the lower piston cylinder (14).

4. The pneumatic piston stop valve according to claim 1 or 2, characterized in that: A plurality of ∩-shaped windows are evenly formed in the circumferential direction of the lower ring surface of the guide ring (4).

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