A three-chamber piston pumping device

Abstract

This application relates to a three-chamber piston pumping device, comprising a housing, a piston, and a piston rod. A first end cap and a second end cap are respectively installed at both ends of the housing. The first end cap has an inlet and an outlet, and the second end cap has an air inlet and an air outlet. The piston divides the inner cavity of the housing into a first chamber and a second chamber. The piston rod passes through the second end cap, and its end is connected to the piston. The outer circumferential surface of the piston has two sets of sealing rings, and an annular transfer groove is provided on the outer circumferential surface of the piston at the location of the two sets of sealing rings. The piston rod has an intermediate cavity, and a vent is provided in the middle of the piston. The two ends of the vent are connected to the transfer groove and the intermediate cavity, respectively. This application has the effect of reducing air leakage between the first and second chambers.

Description

Technical Field

[0001] This application relates to the field of pumping devices, and more particularly to a three-chamber piston pumping device. Background Technology

[0002] In the transfer, transportation, or quantitative extraction of natural gas, oil-free piston compressors are often required for auxiliary pumping.

[0003] Existing oil-free piston compressors include a cylinder and a piston. The piston divides the cylinder into a lower chamber and an upper chamber. The upper chamber is used for the injection and discharge of compressed air. The pressure change in the upper chamber drives the piston to move up and down, thereby changing the volume of the lower chamber to draw in and discharge natural gas.

[0004] However, when the piston reciprocates for a long time, the piston's sealing structure is prone to wear, which can lead to seal failure. Compressed gas in the upper chamber can then enter the natural gas in the lower chamber, which can easily cause a safety accident. Summary of the Invention

[0005] To reduce cross-contamination of gases, this application provides a three-chamber piston pumping device.

[0006] This application provides a three-chamber piston pumping device, which adopts the following technical solution:

[0007] A three-chamber piston pumping device includes a housing, a piston, and a piston rod. A first end cap and a second end cap are respectively installed at both ends of the housing. The first end cap has an inlet and an outlet, and the second end cap has an air inlet and an air outlet. The piston divides the inner cavity of the housing into a first chamber and a second chamber. The piston rod passes through the second end cap, and its end is connected to the piston. The outer circumferential surface of the piston has two sets of sealing rings, and an annular transfer groove is provided on the outer circumferential surface of the piston at the location of the two sets of sealing rings. The piston rod has an intermediate cavity, and a vent is provided in the middle of the piston. The two ends of the vent are connected to the transfer groove and the intermediate cavity, respectively. The intermediate cavity is used to connect to the external atmosphere or to transport high-pressure inert gas.

[0008] By adopting the above technical solution, one end of the intermediate chamber can be connected to the external atmosphere, so that the gas pressure in the transfer tank is normal atmospheric pressure. The natural gas in the first chamber has a certain pressure, and the compressed gas in the second chamber also has high pressure. That is, the gas pressure in the first chamber and the second chamber is higher than the gas pressure in the intermediate chamber. Therefore, when any set of sealing rings wears and fails, the leaked gas in the first chamber or the second chamber will preferentially enter the transfer tank and be discharged through the vent and the intermediate chamber, thereby reducing the mixing of gas between the first chamber and the second chamber and thus reducing natural gas safety accidents.

[0009] When inert gas at a certain pressure is introduced into the intermediate cavity, the gas pressure in the intermediate cavity is higher than that in the first and second chambers. Therefore, when any set of sealing rings wears out, the high-pressure inert gas in the intermediate cavity will preferentially enter the first or second chamber through the leak point to prevent the gas in the first or second chamber from leaking out, thereby reducing the mixing of gas between the first and second chambers. Furthermore, the mixing of inert gas and natural gas is relatively safe, thus reducing natural gas safety accidents.

[0010] Optionally, a core tube is provided through the piston rod, and the annular gap formed between the outer circumferential surface of the core tube and the inner circumferential surface of the piston rod is the intermediate cavity. One end of the core tube extends into the first cavity, and the other end of the core tube is exposed outside the piston rod. The exposed end of the core tube is provided with a backflush tube and a pressure sensor.

[0011] By adopting the above technical solution, firstly, the connection between the core tube and the first chamber allows the pressure of the natural gas in the first chamber to be transmitted to the pressure sensor, thereby enabling real-time detection of the gas pressure in the first chamber and thus determining the gas leakage situation in the first chamber for timely maintenance.

[0012] Secondly, the backflush pipe can be opened to connect the first chamber with the outside atmosphere. Then, the force of the high-pressure natural gas entering the first chamber can be used to squeeze out the residual gas in the first chamber. The residual gas is discharged out through the backflush pipe, thereby ensuring the purity of the gas in the first chamber. Then the backflush pipe can be closed to facilitate the normal transportation of natural gas.

[0013] Optionally, the piston rod is rotatably sealed to the piston, and the end face of the piston is provided with an anti-rotation groove. The first end cap is provided with an anti-rotation block for cooperating with the anti-rotation groove. The piston includes a core and an annular mounting tube. The core includes two circular blocks spaced apart along the length of the piston rod. The gap between the two circular blocks is the vent passage. The mounting tube includes two branch pipes spaced apart along the length of the piston rod. The branch pipes are sleeved and fixed on the circular blocks. Two sets of sealing rings are respectively located on the two branch pipes, and the annular gap between the two branch pipes is the transfer groove. A sealing ring coaxial with the piston rod is provided in the transfer groove. The upper and lower sides of the sealing ring both extend an annular sealing piece towards the piston rod axis. The end face of the branch pipe is provided with an anti-rotation element for restricting the rotation of the sealing piece. The opposing surfaces of the two sealing pieces are provided with first serrations, and a rubber ring is provided in the annular gap between the two sealing pieces. The rubber ring and sealing ring are connected in a non-rotating manner. Both ends of the rubber ring are provided with second serrations that cooperate with the first serration. The outer circumferential surface of the rubber ring abuts against the inner circumferential surface of the sealing ring. The inner circumferential surface of the rubber ring is provided with a third serration. The piston rod is fixed with multiple connecting rods located in the vent passage. The ends of each connecting rod are connected to a drive ring. The drive ring is coaxially arranged with the piston rod. The outer circumferential surface of the drive ring is fixed with a fourth serration that cooperates with the third serration. A limiting structure is provided between the exposed end of the piston rod and the second end cap. When the piston rod rotates in the forward direction, the cooperation of the third and fourth serrations will force the rubber ring to expand outward. When the rubber ring expands outward, the cooperation of the first and second serrations will force the sealing plate to deform and move along the piston rod axis and abut against the end face of the branch pipe. The expansion of the rubber ring also forces the outer circumferential surface of the sealing ring to fit against the inner circumferential surface of the housing. The limiting structure restricts the rotation of the piston rod.

[0014] By adopting the above technical solution, the sealing ring does not come into contact with the inner wall of the casing during normal natural gas pumping, thereby reducing long-term friction damage to the sealing ring.

[0015] The drive ring rotates at a certain angle, and the engagement of the third and fourth saw teeth forces the rubber ring to expand outward. As the rubber ring expands, the engagement of the first and second saw teeth forces the sealing plate to deform and move along the piston rod axially and abut against the end face of the branch pipe. At the same time, the expansion of the rubber ring also forces the outer circumferential surface of the sealing ring to fit against the inner circumferential surface of the housing, thereby sealing the gap between the transfer groove and the vent. Then, the rotation of the piston rod is restricted by the limiting structure to limit the state of the rubber ring, so as to ensure the sealing effect of the sealing ring and the sealing plate, thereby reducing the cross-contamination of gas in the first or second chamber during long-term shutdown, and ensuring the purity of the gas in the second chamber.

[0016] Optionally, both ends of the drive ring are fixed with a fifth sawtooth, and the inner diameter of the opposite face of the sealing plate is provided with a sixth sawtooth. The sixth sawtooth has an inclination direction opposite to that of the first sawtooth, and the sixth sawtooth cooperates with the fifth sawtooth. When the rubber ring forces the sealing ring to expand outward, the cooperation of the sixth and fifth sawtooth forces the sealing plate to deform and move along the piston rod axial direction and abut against the end face of the branch pipe.

[0017] By adopting the above technical solution, when the rubber ring expands outward, that is, when the rubber ring and the drive ring move away radially, the sealing plate will be forced to move axially and radially through the cooperation of the first and second saw teeth. The radial movement of the sealing plate will drive the sixth saw tooth to move radially relative to the fifth saw tooth. Then, through the cooperation of the fifth and sixth saw teeth, the axial deformation of the sealing plate will be further forced. The sealing plate moves axially to a state of tightly abutting the groove wall of the transfer groove, which further improves the sealing strength and sealing completeness.

[0018] Optionally, the anti-rotation component includes a protrusion fixed to the inner diameter of the end face of the branch pipe, and a limiting groove provided at the inner diameter of the surface of the sealing sheet, the depth of the limiting groove being greater than the height of the protrusion, the protrusion being inserted into the limiting groove; the protrusion is provided with an air injection hole extending radially through the piston rod, the air injection hole being in communication with the vent passage, and the sealing sheet having a switching hole; when the sealing sheet is not deformed, the air injection hole is in communication with the axial gap between the sealing sheet and the branch pipe, and the switching hole is closed; when the sealing sheet is deformed and abuts against the end face of the branch pipe, the air injection hole is in communication with the gap between the sealing ring and the rubber ring through the switching hole.

[0019] By adopting the above technical solution, when the sealing sheet is not deformed, the air injection hole is connected to the axial gap between the sealing sheet and the branch pipe. Therefore, the air injection hole will connect the ventilation channel and the transfer groove, so that the high-pressure inert gas in the ventilation channel can fill the transfer groove to reduce leakage and cross-flow of gas in the first chamber or the second chamber.

[0020] When the sealing plate deforms and abuts against the end face of the branch pipe, i.e. when a strong seal is required, the air injection hole is connected to the gap between the sealing ring and the rubber ring through the switching hole. That is, the air injection hole connects the vent and the inner enclosed space of the sealing ring. The pressure of the high-pressure inert gas is applied to the inner enclosed space of the sealing ring and the sealing plate to apply the outward deformation pressure to the sealing ring and the sealing plate, thereby improving the contact effect of the sealing ring and the sealing plate against the wall of the transfer groove, and thus improving the sealing effect.

[0021] Optionally, the piston rod is rotatably sealed to the piston, the housing is provided with a drive assembly for driving the piston rod to rotate, both end faces of the piston are provided with anti-rotation grooves, and the first end cap and the second end cap are provided with anti-rotation blocks for cooperating with the anti-rotation grooves; the piston includes a core and an annular mounting tube, the core includes two circular blocks spaced apart along the length of the piston rod, the gap between the two circular blocks is the vent passage, the transfer groove is located in the middle of the outer circumferential surface of the mounting tube, the outer circumferential surface of the mounting tube is provided with an annular mounting groove, the surface of the sealing ring facing away from the inner wall of the housing is integrally formed with sealing fins, the sealing fins are fixedly connected to the bottom of the mounting groove, the surface of the sealing ring facing the inner wall of the housing is sequentially provided with a positive dynamic sealing area, a static sealing area and a reverse dynamic sealing area along the length of the housing; the inner circumferential surface of the mounting tube is provided with an annular sliding cavity, the sliding cavity is provided with a sliding tube sliding along the piston rod axial direction, the sliding tube and the piston rod are connected to the piston rod. The piston rod is coaxially arranged, and multiple connecting rods located within the venting passage are fixed to the piston rod. Each connecting rod's end is connected to a drive ring, which is coaxially arranged with the piston rod. The outer circumferential surface of the drive ring is threadedly connected to the inner circumferential surface of the sliding tube. The mounting tube has an elastic skeleton, comprising multiple first and second spring pieces. The first and second spring pieces are evenly staggered along the circumference, and the ends of the first and second spring pieces are fixedly connected by a radially arranged third spring piece. The mounting tube has a movable cavity along its radial direction, and the elastic skeleton is located within the movable cavity. Support protrusions are provided on the opposing inner walls of the movable cavity, and two of these support protrusions simultaneously abut against the middle of the third spring piece of the elastic skeleton. A groove is provided on the surface of the sealing ring, and the outer diameter portion of the elastic skeleton is inserted into the groove. An annular V-shaped groove is provided on the outer circumferential surface of the sliding tube, and the inner diameter portion of the elastic skeleton is inserted into the V-shaped groove.

[0022] By adopting the above technical solution, when the piston moves to the first end cover, the anti-rotation block and the anti-rotation groove cooperate to fix the piston and the housing in a circumferential direction. Then, the drive assembly drives the piston rod to rotate in the forward direction. The drive ring and the sliding tube are threaded together to drive the sliding tube to rotate. Since the sliding tube and the piston are anti-rotationally connected, the sliding tube will move axially a certain distance away from the first end cover. The V-groove and the elastic skeleton cooperate to drive the elastic skeleton to deflect relative to the fulcrum protrusion, so as to drive the sealing ring to rotate around the center line, switching the positive dynamic sealing area to the state of abutting against the inner wall of the housing. Then, during the movement of the piston toward the second end cover, the positive dynamic sealing area continues to maintain the abutting state. That is, this process is the forward movement of the piston. During the forward movement, the positive dynamic sealing area undertakes the sealing function.

[0023] When the piston moves to the second end cap, the anti-rotation block and anti-rotation groove work together to fix the piston and the housing circumferentially. Then, the drive assembly drives the piston rod to rotate in the opposite direction. The drive ring and the sliding tube are threaded together to drive the sliding tube to rotate. Since the sliding tube and the piston are anti-rotationally connected, the sliding tube will move axially a certain distance away from the second end cap. The V-groove and the elastic skeleton work together to drive the elastic skeleton to deflect relative to the fulcrum protrusion, thereby causing the sealing ring to rotate around the center line. This switches the reverse dynamic sealing area to the state of abutting against the inner wall of the housing. Then, during the piston's movement toward the first end cap, the reverse dynamic sealing area continues to maintain the abutting state. That is, this process is the reverse movement of the piston. During the reverse movement, the reverse dynamic sealing area assumes the sealing function.

[0024] When the machine is shut down for an extended period of time, the axial movement of the sliding tube can be used to adjust the static sealing area to abut against the inner wall of the housing, thus allowing the static sealing area to assume the sealing function.

[0025] In summary, by coordinating the drive assembly, sliding tube, and elastic skeleton according to the different states of the piston, the position of the sealing ring can be controlled in a targeted manner. This makes the local wear of the sealing ring controllable and the direction of local wear singular, thereby enabling wear as evenly as possible, and thus extending the sealing time and sealing effect.

[0026] Furthermore, by utilizing the controllability of the axial movement of the sliding tube, the deflection position of the sealing ring can be accurately controlled, thereby effectively controlling the contact state of the static sealing zone, the forward dynamic sealing zone, and the reverse dynamic sealing zone, and thus improving the sealing effect.

[0027] Optionally, the sliding tube is provided with a through hole parallel to the axial direction of the piston rod, and the middle of the outer peripheral surface of the sliding tube is provided with a first annular groove, the axial width of the first annular groove being greater than the axial width of the transfer groove, and the first annular groove connecting the transfer groove and the through hole respectively; the inner peripheral surface of the sliding tube is provided with a second annular groove, the second annular groove connecting the vent and the through hole respectively.

[0028] By adopting the above technical solution, and by setting perforations, a first annular groove, and a second annular groove, the ventilation channel and the transfer groove are made interconnected, so as to facilitate the unblocking of gas leakage in the first chamber and the second chamber.

[0029] Optionally, the sealing fins are configured in two sets and symmetrically arranged around the center line of the sealing ring. Each set of sealing fins includes two sealing fins. The bottom of the mounting groove has a slot for inserting the sealing fins, and the mating position between the sealing fins and the slots is filled with adhesive. The mounting tube has a first flow channel and a second flow channel. The first flow channel is located away from the first end cover relative to the movable cavity, and the second flow channel is located closer to the first end cover relative to the movable cavity. One end of both the first and second flow channels is connected to the sliding cavity. The other end of the first flow channel is connected to the gap between the two sealing fins of one set of sealing fins, and the other end of the second flow channel is connected to the gap between the two sealing fins of the other set of sealing fins. The sealing ring has a first deformation groove, the opening of which is connected to the first flow channel. The first deformation groove extends along the surface contour of the positive dynamic sealing area. The sealing ring also has a second deformation groove. The groove opening is connected to the second flow channel. The second deformation groove extends along the surface contour of the reverse dynamic sealing area. Both the first and second deformation grooves have multiple branch grooves extending towards the center of the sealing ring's cross-section. The length of each branch groove gradually increases in a direction away from the piston rod axis. The outer circumferential surface of the sliding tube has an annular third and fourth annular grooves, both of which are connected to the perforation. When the sliding tube moves to cause the forward dynamic sealing area of ​​the sealing ring to abut against the inner wall of the housing, the third annular groove of the sliding tube is connected to the first flow channel, and the fourth annular groove is connected to the movable cavity. When the sliding tube moves to cause the reverse dynamic sealing area of ​​the sealing ring to abut against the inner wall of the housing, the fourth annular groove of the sliding tube is connected to the second flow channel, and the third annular groove is connected to the movable cavity. When the sliding tube moves to cause the static sealing area of ​​the sealing ring to abut against the inner wall of the housing, the fourth annular groove of the sliding tube is connected to the second flow channel, and the third annular groove is connected to the first flow channel.

[0030] By adopting the above technical solution, when the piston is about to move forward, the sliding tube moves to drive the forward dynamic sealing area of ​​the sealing ring to abut against the inner wall of the housing. At this time, the third annular groove of the sliding tube is connected to the first flow channel, and the fourth annular groove is connected to the movable cavity. Therefore, the high-pressure inert gas in the vent will enter the first flow channel in sequence through the second annular groove, the perforation, and the third annular groove. The high-pressure inert gas in the first flow channel will enter the first deformation groove. The pressure in the first deformation groove increases, thereby driving the sealing ring to expand. The part with the greatest expansion is the forward dynamic sealing area. That is, the forward dynamic sealing area expands to fit more tightly against the inner wall of the housing, thereby improving the sealing effect. Secondly, by setting the extension direction of the first deformation groove, the surface expansion of the forward dynamic sealing area is more uniform, and the surface contact pressure is stable, which can greatly improve the sealing stability.

[0031] Conversely, when the piston is about to move in the reverse direction, the fourth annular groove of the sliding tube connects with the second flow channel, and the third annular groove connects with the moving chamber. The high-pressure inert gas in the vent channel will pass through the second annular groove, the perforation, and the fourth annular groove in sequence to enter the second flow channel. The high-pressure inert gas in the second flow channel will enter the second deformation groove, and the pressure in the second deformation groove will increase, thereby causing the sealing ring to expand. The part with the greatest expansion is the reverse dynamic sealing area. That is, the reverse dynamic sealing area expands to fit more tightly against the inner wall of the shell, thereby improving the sealing effect.

[0032] When a long-term shutdown is required, the static sealing area of ​​the sealing ring abuts against the inner wall of the housing. At this time, the fourth annular groove of the sliding tube is connected to the second flow channel, and the third annular groove is connected to the first flow channel. Therefore, high-pressure inert gas will enter the first deformation groove and the second deformation groove respectively, thereby forcing the sealing ring to expand evenly, so that the static sealing area of ​​the sealing ring abuts against the inner wall of the housing more closely, thereby improving the sealing effect.

[0033] Optionally, the static sealing area, the forward dynamic sealing area, and the reverse dynamic sealing area are all arc segments. The center of curvature of the static sealing area is located on the center line of the sealing ring. The center of curvature of the forward dynamic sealing area is located on the side closer to the first end cover relative to the center line of the sealing ring. The center of curvature of the reverse dynamic sealing area is located on the side closer to the second end cover relative to the center line of the sealing ring.

[0034] By adopting the above technical solution, and by setting the curvature center points of the static sealing area, the forward dynamic sealing area, and the reverse dynamic sealing area, when the sealing ring is flipped in the forward or reverse direction, as the degree of flipping increases, the unworn parts of the forward dynamic sealing area and the reverse dynamic sealing area will come into contact, thereby achieving wear compensation and maintaining the stability of the sealing effect.

[0035] In summary, this application includes at least one of the following beneficial technical effects:

[0036] 1. By setting up an intermediate chamber, a vent, and a transfer tank, and by changing the gas pressure in the intermediate chamber to be higher or lower than that in the first and second chambers, when any set of sealing rings wears out, the leaked gas in the first or second chamber will preferentially enter the transfer tank and be discharged, or the high-pressure inert gas in the intermediate chamber will be discharged into the first or second chamber through the leak point, thereby reducing cross-contamination between the first and second chambers and thus reducing natural gas safety accidents;

[0037] 2. By setting up a piston anti-rotation connection, drive ring, rubber ring, sealing ring and sealing plate, the rotation of the piston rod is used to control the outward expansion deformation of the rubber ring. Then, by using the guiding fit of various serrations, the outward expansion deformation force of the rubber ring is converted into the deformation force that forces the sealing ring and sealing plate to deform, thereby sealing the gap between the transfer groove and the ventilation channel, thereby reducing the cross-flow of gas between the first chamber or the second chamber during long-term shutdown, and ensuring the purity of the gas in the second chamber;

[0038] 3. Depending on the state of the piston, the position of the sealing ring is controlled in a targeted manner through the cooperation of the drive assembly, sliding tube and elastic skeleton. This makes the local wear of the sealing ring controllable and the direction of local wear singular, so as to achieve wear as evenly as possible, thereby extending the sealing time and sealing effect. Attached Figure Description

[0039] Figure 1 This is a cross-sectional view of the overall structure of Embodiment 1.

[0040] Figure 2 This is a partial cross-sectional view of the piston in Example 1.

[0041] Figure 3 This is a partial cross-sectional view of the piston in Example 2.

[0042] Figure 4 yes Figure 3 A magnified view of a portion of point A in the middle.

[0043] Figure 5 This is a longitudinal cross-sectional view of the drive ring and rubber ring in Example 2.

[0044] Figure 6 This is a schematic diagram of the limiting structure in Example 2.

[0045] Figure 7 This is a partial cross-sectional view of the piston in Example 3.

[0046] Figure 8 yes Figure 7 A magnified view of a section at point B in the middle.

[0047] Figure 9 This is a partial cross-sectional view of the sealing ring in Example 3.

[0048] Figure 10 This is a schematic diagram of the driving component in Embodiment 3.

[0049] Figure 11 This is a schematic diagram of the elastic skeleton in Example 3.

[0050] Figure 12 This is a partial cross-sectional view of the sealing ring in Example 4.

[0051] Explanation of reference numerals in the attached drawings: 1. Housing; 2. Piston rod; 3. Piston; 5. Sealing ring; 6. Rubber ring; 7. Sealing ring; 9. Elastic skeleton; 11. First end cap; 110. First chamber; 111. Inlet; 112. Outlet; 12. Second end cap; 120. Second chamber; 121. Air inlet; 122. Air outlet; 13. Pull rod; 20. Intermediate cavity; 21. Clamping plate; 22. Core tube; 23. Connecting rod; 24. 241. Drive ring; 242. Fourth serration; 243. Fifth serration; 25. Anti-rotation groove; 251. Anti-rotation block; 31. Ventilation channel; 32. Transfer groove; 33. Circular block; 331. Sliding bar; 34. Branch pipe; 341. Protrusion; 342. Air injection port; 35. Secondary pipe; 351. Through rod; 36. Main pipe; 37. Mounting groove; 371. Retaining ring; 372. Movable cavity; 373. Pivot protrusion; 38. Sliding cavity; 39. Sliding tube; 391, Sliding groove; 392, Perforation; 393, First annular groove; 394, Second annular groove; 395, V-groove; 396, First flow channel; 397, Second flow channel; 398, Third annular groove; 399, Fourth annular groove; 50, Branch groove; 51, Forward dynamic sealing zone; 52, Static sealing zone; 53, Reverse dynamic sealing zone; 54, Sealing fin; 55, Bend; 56, Slot; 57, Central convex part; 58. 59. First deformation groove; 60. Second deformation groove; 61. Protrusion; 62. Second sawtooth; 63. Third sawtooth; 64. Pin; 65. Pin groove; 71. Sealing plate; 72. First sawtooth; 73. Sixth sawtooth; 74. Limiting groove; 75. Groove; 76. Switching hole; 81. First gear; 82. Second gear; 83. Servo motor; 84. Gear post; 91. First spring; 92. Second spring; 93. Third spring. Detailed Implementation

[0052] The following is in conjunction with the appendix Figure 1-12 This application will be described in further detail.

[0053] Embodiment 1 of this application discloses a three-chamber piston pumping device.

[0054] Reference Figure 1 and Figure 2 The three-chamber piston type 3 pumping device includes a housing 1, a piston 3 and a piston rod 2. A first end cover 11 and a second end cover 12 are respectively installed at both ends of the housing 1. The installation method can be that the first end cover 11 and the second end cover 12 are welded to both ends of the housing 1. In this embodiment, the first end cover 11 and the second end cover 12 are connected together by a pull rod 13. The pull force of the pull rod 13 is used to fix the first end cover 11 and the second end cover 12 to both ends of the housing 1, so as to facilitate subsequent disassembly and maintenance.

[0055] The piston 3 divides the inner cavity of the housing 1 into a first chamber 110 and a second chamber 120. The first end cover 11 has an inlet 111 and an outlet 112. The inlet 111 and the outlet 112 are respectively provided with one-way valves (not shown in the figure). The inlet 111 is used to restrict the natural gas from entering the first chamber 110 in one direction, and the outlet 112 is used to restrict the natural gas from exiting the first chamber 110 in one direction.

[0056] The second end cap 12 has an air inlet 121 and an air outlet 122, which are used to connect to the air inlet and outlet of the air compressor, respectively.

[0057] The piston rod 2 passes through the second end cap 12, and one end of the piston rod 2 is fixedly connected to the piston 3. Specifically, the piston 3 has a retaining plate 21 fixed to its end face by bolts, and the inner diameter of the retaining plate 21 is embedded in the annular groove on the circumference of the piston rod 2.

[0058] That is, by injecting and venting compressed air into the second chamber 120, the air pressure in the second chamber 120 is changed, thereby driving the piston 3 to move up and down, and thus changing the volume of the first chamber 110, so as to draw in, compress and vent the natural gas.

[0059] The piston rod 2 is a tubular structure, and a core tube 22 is fixed inside the piston rod 2. The annular gap formed between the outer circumferential surface of the core tube 22 and the inner circumferential surface of the piston rod 2 is set as an intermediate cavity 20. One end of the core tube 22 is exposed in the first chamber 110, and the other end of the core tube 22 is exposed outside the piston rod 2. The end of the core tube 22 exposed in the housing 1 is provided with a recoil tube and a pressure sensor (not shown in the figure).

[0060] Because the core tube 22 is connected to the first chamber 110, the backflush pipe is closed at this time, allowing the pressure of the natural gas in the first chamber 110 to be transmitted to the pressure sensor, thereby enabling real-time detection of the gas pressure in the first chamber 110 and determining the gas leakage situation in the first chamber 110 for timely maintenance. Furthermore, before pumping natural gas, the backflush pipe can be opened to connect the first chamber 110 with the outside atmosphere. Then, the force of the high-pressure natural gas entering the first chamber 110 is used to displace the residual gas in the first chamber 110. The residual gas is discharged outward through the backflush pipe, thereby ensuring the purity of the gas in the first chamber 110. Then, the backflush pipe is closed to allow normal natural gas pumping.

[0061] The outer circumferential surface of the piston 3 has two sets of sealing rings 5. In this embodiment, one set of sealing rings 5 ​​includes one sealing ring 5. The outer circumferential surface of the piston 3 is provided with an annular transfer groove 32 at the part of the two sets of sealing rings 5. The middle part of the piston 3 is provided with a venting channel 31. In this embodiment, the venting channel 31 is a hole drilled and formed along the radial direction of the piston 3. The two ends of the venting channel 31 are respectively connected to the transfer groove 32 and the intermediate cavity 20. That is, the lower end of the intermediate cavity 20 is connected to the venting channel 31, while the upper end of the intermediate cavity 20 can be connected to the external atmosphere or connected to a pipeline that can transport high-pressure inert gas.

[0062] When the intermediate chamber 20 is connected to the outside atmosphere, the gas pressure in the transfer tank 32 is normal atmospheric pressure, while the natural gas in the first chamber 110 has a certain pressure, and the compressed gas in the second chamber 120 also has high pressure. That is, the gas pressure in the first chamber 110 and the second chamber 120 is higher than the gas pressure in the intermediate chamber 20. Therefore, when any set of sealing rings 5 ​​wears and fails, the leaked gas in the first chamber 110 or the second chamber 120 will preferentially enter the transfer tank 32. The leaked gas will be discharged to the outside atmosphere through the vent 31 and the intermediate chamber 20, thereby reducing the cross-contamination and mixing between the first chamber 110 and the second chamber 120, and thus reducing natural gas safety accidents.

[0063] When an inert gas at a certain pressure is introduced into the intermediate cavity 20, the pressure of the high-pressure inert gas in the intermediate cavity 20 is higher than that in the first chamber 110 and the second chamber 120. Therefore, when any set of sealing rings 5 ​​wears and fails, the high-pressure inert gas in the intermediate cavity 20 will preferentially enter the first chamber 110 or the second chamber 120 through the leak point to prevent the gas in the first chamber 110 or the second chamber 120 from leaking outward, thereby reducing the cross-contamination between the first chamber 110 and the second chamber 120. Furthermore, the mixing of inert gas and natural gas is relatively safe, thereby reducing natural gas safety accidents.

[0064] Example 2

[0065] The difference between Example 2 and Example 1 is that, as Figure 3 , Figure 4 As shown, the piston 3 has an anti-rotation groove 25 on its end face, and the first end cover 11 has an anti-rotation block 251 for cooperating with the anti-rotation groove 25. That is, when the piston 3 moves to the first end cover 11, the anti-rotation block 251 cooperates with the anti-rotation groove 25 to fix the piston 3 and the housing 1 in a circumferential direction. The piston rod 2 is rotatably and sealed to the piston 3, so rotating the piston rod 2 will not drive the piston 3 to rotate synchronously.

[0066] The piston 3 includes a core and an annular mounting tube. The core includes two circular blocks 33. Both circular blocks 33 are connected to the piston rod 2 through a clamping plate 21. The two circular blocks 33 are spaced apart along the length of the piston rod 2, and the gap between the two circular blocks 33 is a vent 31.

[0067] The mounting pipe includes two branch pipes 34, which correspond one-to-one with the circular block 33. The branch pipes 34 are sleeved and fixed on the circular block 33, specifically by welding. Two sets of sealing rings 5 ​​are located on the two branch pipes 34 respectively, and the two branch pipes 34 are spaced apart along the length of the piston rod 2. The annular gap between the two branch pipes 34 is the transfer groove 32.

[0068] like Figure 4 , Figure 5 As shown, the piston rod 2 is fixed with multiple connecting rods 23 located in the ventilation channel 31. The ends of each connecting rod 23 are connected to a drive ring 24. The drive ring 24 is coaxially arranged with the piston rod 2. The outer circumferential surface of the drive ring 24 is fixed with a fourth serration 241. That is, when the piston rod 2 rotates, the drive ring 24 can be driven to rotate relative to the piston 3 through the connecting rods 23.

[0069] like Figure 4 As shown, a sealing ring 7 is provided in the transfer groove 32. The sealing ring 7 is made of rubber and is coaxial with the piston rod 2. Both the upper and lower sides of the sealing ring 7 extend an annular sealing piece 71 towards the axis of the piston rod 2. The end face of the branch pipe 34 is provided with an anti-rotation member to limit the rotation of the sealing piece 71. Specifically, the anti-rotation member includes a protrusion 341 fixed at the inner diameter of the end face of the branch pipe 34. There are multiple protrusions 341, and each protrusion 341 is arranged at intervals along the circumference of the branch pipe 34. A limiting groove 74 is provided at the inner diameter of the surface of the sealing piece 71. The depth of the limiting groove 74 is greater than the height of the protrusion 341. The protrusion 341 is inserted into the limiting groove 74, thereby making the sealing ring 7 and the branch pipe 34 anti-rotation connected.

[0070] The protrusion 341 is provided with an air injection hole 342, which is arranged radially along the branch pipe 34 and is connected to the air passage 31. In addition, the sealing plate 71 is provided with a switching hole 76, which is arranged radially along the sealing plate 71.

[0071] The two sealing plates 71 are provided with a first serration 72 on their opposite surfaces. The first serration 72 is an annular structure and its cross-section is serrated. The inner diameter of the opposite surfaces of the sealing plates 71 is provided with a sixth serration 73. The sixth serration 73 is an annular structure and its cross-section is serrated. The tooth surface inclination direction of the sixth serration 73 is opposite to that of the first serration 72. The two end faces of the drive ring 24 are fixed with a fifth serration 242. The fifth serration 242 is an annular structure and its cross-section is serrated. The fifth serration 242 cooperates with the sixth serration 73.

[0072] A rubber ring 6 is provided in the annular gap between the two sealing plates 71. The rubber ring 6 is coaxially arranged with the piston rod 2. The rubber ring 6 and the sealing ring 7 are connected in a non-rotational manner. Specifically, the outer circumferential surface of the rubber ring 6 is attached to the inner circumferential surface of the sealing ring 7. The outer circumferential surface of the rubber ring 6 has a protruding protrusion 61. The inner circumferential surface of the sealing ring 7 has a groove 75. The groove 75 and the protrusion 61 cooperate, that is, the rubber ring 6 and the sealing ring 7 are connected in a non-rotational manner.

[0073] like Figure 4 , Figure 5 As shown, the inner circumferential surface of the rubber ring 6 is provided with a third serration 63, which cooperates with the fourth serration 241 of the drive ring 24.

[0074] The rubber ring 6 has a second serration 62 on both ends. The second serration 62 has a ring structure and the cross-section of the second serration 62 is serrated. The second serration 62 cooperates with the first serration 72.

[0075] A limiting structure is provided between the exposed end of the piston rod 2 and the second end cap 12. The limiting structure is used to restrict the rotation of the piston rod 2. Specifically, as follows: Figure 6 As shown, the limiting structure includes a pin 64, which is axially slidably connected to the piston rod 2. The end face of the second end cover 12 is provided with a pin groove 65. The rotation of the piston rod 2 is limited by the insertion and engagement of the pin 64 and the pin groove 65.

[0076] During normal natural gas pumping, the sealing plate 71 does not deform, and the sealing ring 7 does not contact the inner wall of the housing 1, thereby reducing long-term friction damage to the sealing ring 7. Furthermore, the air injection port 342 is connected to the axial gap between the sealing plate 71 and the branch pipe 34. Therefore, the air injection port 342 will connect the ventilation channel 31 and the transfer groove 32, so that the high-pressure inert gas in the ventilation channel 31 can fill the transfer groove 32, thereby reducing leakage and cross-flow of gas in the first chamber 110 or the second chamber 120.

[0077] When a long-term shutdown is required, i.e., when pumping is stopped for an extended period, first move piston 3 to the first end cover 11. Through the engagement of anti-rotation block 251 and anti-rotation groove 25, piston 3 and housing 1 are circumferentially fixed. Then, rotate piston rod 2 forward by a certain angle, driving ring 24 to rotate forward (see...). Figure 5(in the direction of the arrow), the cooperation of the third sawtooth 63 and the fourth sawtooth 241 will force the rubber ring 6 to expand outward. When the rubber ring 6 expands outward, the cooperation of the first sawtooth 72 and the second sawtooth 62 will force the sealing plate 71 to deform and move along the piston rod 2 and abut against the end face of the branch pipe 34. The sealing plate 71 also expands outward. Therefore, the radial movement of the sealing plate 71 will drive the sixth sawtooth 73 to move radially relative to the fifth sawtooth 242. Then, through the cooperation of the fifth sawtooth 242 and the sixth sawtooth 73, the axial deformation of the sealing plate 71 will be further forced. The sealing plate 71 moves axially to a state of tightly abutting the groove wall of the transfer groove 32, which further improves the sealing strength and sealing completeness.

[0078] Meanwhile, the outward expansion of the rubber ring 6 forces the outer circumferential surface of the sealing ring 7 to fit against the inner circumferential surface of the housing 1, thereby sealing the gap between the transfer groove 32 and the vent 31. Then, the rotation of the piston rod 2 is restricted by the limiting structure to limit the state of the rubber ring 6, so as to ensure the sealing effect of the sealing ring 7 and the sealing sheet 71, thereby reducing the mutual cross-flow of gas in the first chamber 110 or the second chamber 120 during long-term shutdown, and ensuring the gas purity of the second chamber 120.

[0079] Furthermore, when the sealing plate 71 deforms and abuts against the end face of the branch pipe 34, the air injection hole 342 connects with the gap between the sealing ring 7 and the rubber ring 6 through the switching hole 76. The high-pressure inert gas then enters the inner enclosed space of the sealing ring 7 and the sealing plate 71 through the vent 31, the air injection hole 342, and the switching hole 76 in sequence. The high-pressure inert gas applies outward deformation pressure to the sealing ring 7 and the sealing plate 71, thereby improving the contact effect of the sealing ring 7 and the sealing plate 71 against the wall of the transfer groove 32, and thus improving the sealing effect.

[0080] Example 3

[0081] The difference between Example 3 and Example 2 is that, as Figure 7 As shown, both ends of the piston 3 are provided with anti-rotation grooves 25, and both the first end cover 11 and the second end cover 12 are provided with anti-rotation blocks 251 for cooperating with the anti-rotation grooves 25. That is, when the piston 3 moves to the first end cover 11 or the second end cover 12, the piston 3 is in a state where it cannot rotate with the piston rod 2.

[0082] like Figure 8 , Figure 9 As shown, the installation pipe includes a main pipe 36 and two secondary pipes 35. The two secondary pipes 35 are located at both ends of the main pipe 36. The secondary pipes 35 and the main pipe 36 are fixed by passing through a through rod 351. The two ends of the through rod 351 have nuts, which abut against the end face of the secondary pipes 35. The abutment force is used to clamp and fix the secondary pipes 35 and the main pipe 36. Then, the secondary pipes 35 and the circular block 33 are welded and fixed. An O-ring (not shown in the figure) is provided at the through part of the through rod 351 to ensure sealing.

[0083] The transfer groove 32 is located in the middle of the outer peripheral surface of the main pipe 36. The adjacent end faces of the secondary pipe 35 and the main pipe 36 are provided with stepped grooves. The stepped grooves of the secondary pipe 35 and the main pipe 36 are combined to form the mounting groove 37. The opposite surfaces of the main pipe 36 and the secondary pipe 35 are provided with inclined surfaces. The distance between the two inclined surfaces gradually increases along the direction close to the axis of the housing 1. The inclined surfaces of the main pipe 36 and the secondary pipe 35 enclose and form the movable cavity 372. The inclined surfaces are provided with a fulcrum protrusion 373. The fulcrum protrusion 373 is a ring structure and is coaxially arranged with the piston rod 2.

[0084] The sealing ring 5 is installed in the mounting groove 37. Specifically, the surface of the sealing ring 5 facing away from the inner wall of the housing 1 is integrally formed with sealing fins 54. The connection position between the sealing fins 54 and the sealing ring 5 is set as a bend 55. The bend 55 is used to ensure that the sealing ring 5 has a certain degree of freedom of rotation. The sealing fins 54 are set in two sets and symmetrically arranged around the center line of the sealing ring 5. Each set of sealing fins 54 includes two sealing fins 54. The bottom of the mounting groove 37 is provided with a slot for the sealing fins 54 to be inserted. The mating position between the sealing fins 54 and the slot is filled with adhesive. In addition, two retaining rings 371 are provided in the mounting groove 37 to prevent the sealing ring 5 from detaching from the mounting groove 37.

[0085] The sealing ring 5 has an integrally formed central protrusion 57 on the surface away from the inner wall of the housing 1. The central protrusion 57 is located between the two sets of sealing fins 54. The central protrusion 57 has an annular structure and is coaxial with the piston rod 2. The surface of the central protrusion 57 is provided with an abutment groove for the fulcrum protrusion 373 to abut. That is, the main tube 36 and the secondary tube 35 simultaneously clamp the central protrusion 57 to fix the sealing ring 5.

[0086] like Figure 9 As shown, the surface of the sealing ring 5 facing the inner wall of the housing 1 is sequentially designated as a positive dynamic sealing area 51, a static sealing area 52, and a negative dynamic sealing area 53 along the length of the housing 1. The static sealing area 52, the positive dynamic sealing area 51, and the negative dynamic sealing area 53 are all arc segments. The center of curvature of the static sealing area 52 is located on the center line of the sealing ring 5. The center of curvature of the positive dynamic sealing area 51 is located on the side closer to the first end cover 11 relative to the center line of the sealing ring 5. The center of curvature of the negative dynamic sealing area 53 is located on the side closer to the second end cover 12 relative to the center line of the sealing ring 5.

[0087] like Figure 8 , Figure 9As shown, the inner circumferential surface of the mounting tube is provided with an annular sliding cavity 38. A sliding tube 39 is provided in the sliding cavity 38 along the axial direction of the piston rod 2. The sliding tube 39 is coaxially arranged with the piston rod 2. Specifically, a slide bar 331 parallel to the axial direction of the piston rod 2 is fixed on the outer circumferential surface of the core. A strip-shaped sliding groove 391 is provided on the inner circumferential surface of the sliding tube 39. The sliding groove 391 cooperates with the slide bar 331, so that the sliding tube 39 cannot rotate relative to the piston 3, but can only slide, that is, a non-rotation connection.

[0088] The housing 1 is also provided with a drive assembly, which is used to drive the piston rod 2 to rotate. The outer circumferential surface of the drive ring 24 is threadedly connected to the inner circumferential surface of the sliding tube 39. That is, when the piston rod 2 drives the drive ring 24 to rotate in both directions, the sliding tube 39 can be driven to move up and down through the threaded connection.

[0089] like Figure 10 As shown, the drive assembly includes a servo motor 83 and a gear 84. The servo motor 83 is mounted on the second end cover 12. The exposed end of the piston rod 2 is fixed with a first gear 81. The output shaft of the servo motor 83 is fixed with a second gear 82. One end of the gear 84 is rotatably connected to the second end cover 12. The gear 84 meshes with the first gear 81 and the second gear 82 respectively. That is, the rotation of the servo motor 83 drives the piston rod 2 to rotate through gear transmission. Since the gear 84 is parallel to the axial direction of the piston rod 2, when the piston rod 2 drives the first gear 81 to move axially, it can ensure that the first gear 81 and the gear 84 always remain in a meshed state.

[0090] like Figure 8 , Figure 9 As shown, the sliding tube 39 is provided with a through hole 392 parallel to the axial direction of the piston rod 2. The middle part of the outer peripheral surface of the sliding tube 39 is provided with an annular first groove 393. The axial width of the first groove 393 is greater than the axial width of the transfer groove 32. The first groove 393 connects the transfer groove 32 and the through hole 392 respectively. The inner peripheral surface of the sliding tube 39 is provided with an annular second groove 394. The second groove 394 connects the vent 31 and the through hole 392 respectively.

[0091] That is, by setting the perforation 392, the first annular groove 393 and the second annular groove 394, the ventilation channel 31 and the transfer groove 32 are connected to facilitate the unblocking of gas leakage in the first chamber 110 and the second chamber 120.

[0092] like Figure 11 As shown, the mounting tube is provided with an elastic frame 9. Specifically, the elastic frame 9 includes a plurality of first spring pieces 91 and a plurality of second spring pieces 92. The first spring pieces 91 and the second spring pieces 92 are evenly staggered along the circumference. The ends of the first spring pieces 91 and the ends of the second spring pieces 92 are fixedly connected by a third spring piece 93 arranged radially.

[0093] like Figure 9 As shown, the elastic skeleton 9 is located in the movable cavity 372. The two support protrusions 373 of the movable cavity 372 simultaneously abut against the middle of the third spring piece 93 of the elastic skeleton 9. The surface of the sealing ring 5 is provided with a groove 56. The outer diameter part of the elastic skeleton 9 is inserted into the groove 56. The outer circumferential surface of the sliding tube 39 is provided with an annular V-shaped groove 395. The inner diameter part of the elastic skeleton 9 is inserted into the V-shaped groove 395.

[0094] When the piston 3 moves to the first end cover 11, the anti-rotation block 251 and the anti-rotation groove 25 cooperate to fix the piston 3 and the housing 1 circumferentially. Then, the piston rod 2 is driven to rotate forward by the drive assembly. The drive ring 24 and the sliding tube 39 are threaded together to drive the sliding tube 39 to rotate. Since the sliding tube 39 and the piston 3 are anti-rotation connected, the sliding tube 39 will move axially a certain distance away from the first end cover 11. The V-groove 395 cooperates with the elastic skeleton 9 to drive the elastic skeleton 9 to deflect relative to the fulcrum protrusion 373, so as to drive the sealing ring 5 to rotate around the center line, switching the positive dynamic sealing area 51 to the state of abutting against the inner wall of the housing 1. Then, during the movement of the piston 3 toward the second end cover 12, the positive dynamic sealing area 51 continues to maintain the abutting state. That is, this process is the positive movement of the piston 3. During the positive movement, the positive dynamic sealing area 51 undertakes the sealing function.

[0095] When the piston 3 moves to the second end cover 12, the anti-rotation block 251 and the anti-rotation groove 25 cooperate to fix the piston 3 and the housing 1 circumferentially. Then, the piston rod 2 is driven to rotate in the opposite direction by the drive assembly. The drive ring 24 and the sliding tube 39 are threaded together to drive the sliding tube 39 to rotate. Since the sliding tube 39 and the piston 3 are anti-rotation connected, the sliding tube 39 will move axially a certain distance away from the second end cover 12. The V-groove 395 and the elastic skeleton 9 cooperate to drive the elastic skeleton 9 to deflect relative to the fulcrum protrusion 373, so as to drive the sealing ring 5 to rotate around the center line, switching the reverse dynamic sealing area 53 to the state of abutting against the inner wall of the housing 1. Then, during the movement of the piston 3 toward the first end cover 11, the reverse dynamic sealing area 53 continues to maintain the abutting state. That is, this process is the reverse movement of the piston 3. During the reverse movement, the reverse dynamic sealing area 53 undertakes the sealing function.

[0096] When the machine is shut down for a long time, the axial movement of the sliding tube 39 can be used to adjust the static sealing area 52 to abut against the inner wall of the housing 1, that is, the static sealing area 52 shall bear the sealing function.

[0097] Therefore, based on the different movement trajectories of the piston 3, the position of the sealing ring 5 is specifically controlled through the cooperation of the drive assembly, the sliding tube 39, and the elastic skeleton 9, thereby making the local wear of the sealing ring 5 controllable and the direction of local wear singular, so as to achieve wear as uniformly as possible, thereby extending the sealing time and sealing effect.

[0098] Example 4

[0099] The difference between Example 4 and Example 3 is that, as Figure 12 As shown, the installation tube is provided with a first flow channel 396 and a second flow channel 397. There are two sets of the first flow channel 396 and the second flow channel 397, which are respectively arranged corresponding to two sealing rings 5. The first flow channel 396 is located away from the first end cover 11 relative to the movable cavity 372, and the second flow channel 397 is located close to the first end cover 11 relative to the movable cavity 372. One end of the first flow channel 396 and the second flow channel 397 are connected to the sliding cavity 38. The other end of the first flow channel 396 is connected to the gap between the two sealing fins 54 of one set of sealing fins 54, and the other end of the second flow channel 397 is connected to the gap between the two sealing fins 54 of the other set of sealing fins 54.

[0100] The sealing ring 5 is provided with a first deformation groove 58, the opening of the first deformation groove 58 is connected to the first flow channel 396, and the first deformation groove 58 extends along the surface contour of the forward dynamic sealing area 51. The sealing ring 5 is provided with a second deformation groove 59, the opening of the second deformation groove 59 is connected to the second flow channel 397, and the second deformation groove 59 extends along the surface contour of the reverse dynamic sealing area 53. The middle of the first deformation groove 58 and the second deformation groove 59 are provided with a plurality of branch grooves 50 extending toward the cross-sectional center of the sealing ring 5, and the length of each branch groove 50 gradually increases along the direction away from the axis of the piston rod 2.

[0101] The outer circumferential surface of the sliding tube 39 is provided with an annular third annular groove 398 and a fourth annular groove 399. Both the third annular groove 398 and the fourth annular groove 399 are coaxial with the piston rod 2, and both the third annular groove 398 and the fourth annular groove 399 are connected to the through hole 392. The third annular groove 398 is farther away from the first end cover 11 than the fourth annular groove 399.

[0102] When the piston 3 is about to move forward, that is, when the sliding tube 39 moves to drive the positive dynamic sealing area 51 of the sealing ring 5 to abut against the inner wall of the housing 1, at this time, the third annular groove 398 of the sliding tube 39 moves to a state that communicates with the first flow channel 396, and the fourth annular groove 399 communicates with the movable cavity 372. Therefore, the high-pressure inert gas in the vent 31 will enter the first flow channel 396 in sequence through the second annular groove 394, the perforation 392, and the third annular groove 398. The high-pressure inert gas in the first flow channel 396 will enter the first deformation groove 58. The pressure in the first deformation groove 58 increases, thereby driving the sealing ring 5 to expand. The part with the greatest expansion is the positive dynamic sealing area 51. That is, the positive dynamic sealing area 51 expands to fit more tightly against the inner wall of the housing 1, thereby improving the sealing effect. Secondly, by setting the extension direction of the first deformation groove 58, the surface expansion of the positive dynamic sealing area 51 is more uniform, and the surface contact pressure is stable, which can greatly improve the sealing stability.

[0103] When piston 3 is about to move in the reverse direction, the fourth annular groove 399 of sliding tube 39 moves to a state that communicates with the second flow channel 397, and the third annular groove 398 communicates with the movable cavity 372. The high-pressure inert gas in vent 31 will pass through the second annular groove 394, the perforation 392, and the fourth annular groove 399 in sequence and enter the second flow channel 397. The high-pressure inert gas in the second flow channel 397 will enter the second deformation groove 59. The pressure in the second deformation groove 59 increases, thereby causing the sealing ring 5 to expand. The part with the greatest expansion is the reverse dynamic sealing area 53. That is, the reverse dynamic sealing area 53 expands to fit more tightly against the inner wall of the housing 1, thereby improving the sealing effect.

[0104] When a long-term shutdown is required, when the static sealing area 52 of the sealing ring 5 abuts against the inner wall of the housing 1, the fourth annular groove 399 of the sliding tube 39 is connected to the second flow channel 397, and the third annular groove 398 is connected to the first flow channel 396. Therefore, high-pressure inert gas will enter the first deformation groove 58 and the second deformation groove 59 respectively, thereby forcing the sealing ring 5 to expand uniformly, so that the static sealing area 52 of the sealing ring 5 abuts against the inner wall of the housing 1 more closely, thereby improving the sealing effect.

[0105] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A three-chamber piston (3) type pumping device, characterized in that: The device includes a housing (1), a piston (3), and a piston rod (2). The housing (1) is equipped with a first end cap (11) and a second end cap (12) at its two ends. The first end cap (11) has an inlet hole (111) and an outlet hole (112). The second end cap (12) has an air inlet hole (121) and an air outlet hole (122). The piston (3) divides the inner cavity of the housing (1) into a first chamber (110) and a second chamber (120). The piston rod (2) passes through the second end cap (12). The end of the piston rod (2) is connected to the piston (3). The outer circumferential surface of the piston (3) has two sets of sealing rings (5). The outer circumferential surface of the piston (3) located at the two sets of sealing rings (5) is provided with an annular transfer groove (32). The piston rod (2) has an intermediate cavity (20), and the piston (3) has a vent (31) in the middle. The two ends of the vent (31) are connected to the transfer groove (32) and the intermediate cavity (20) respectively. The intermediate cavity (20) is used to connect to the external atmosphere or to transport high-pressure inert gas. The piston rod (2) and the piston (3) are rotatably sealed together. The end face of the piston (3) is provided with an anti-rotation groove (25). The first end cap (11) is provided with an anti-rotation block (251) for cooperating with the anti-rotation groove (25). The piston (3) includes a core and an annular mounting tube. The core includes two circular blocks (33) spaced apart along the length of the piston rod (2). The gap between the two circular blocks (33) is the passage. The air passage (31) includes two branch pipes (34) spaced apart along the length of the piston rod (2). The branch pipes (34) are fitted and fixed on the circular block (33). Two sets of sealing rings (5) are located on the two branch pipes (34) respectively. The annular gap between the two branch pipes (34) is the transfer groove (32). The transfer groove (32) is provided with a sealing ring (7) coaxial with the piston rod (2). The upper and lower sides of the sealing ring (7) are both extended with an annular sealing piece (71) towards the axis of the piston rod (2). The end face of the branch pipe (34) is provided with an anti-rotation member to restrict the rotation of the sealing piece (71). The opposite surfaces of the two sealing pieces (71) are provided with a first serration (72). A rubber ring (6) is provided in the annular gap between the two sealing plates (71). The rubber ring (6) is connected to the sealing ring (7) in a non-rotational manner. Both ends of the rubber ring (6) are provided with a second serration (62) that cooperates with the first serration (72). The outer circumferential surface of the rubber ring (6) abuts against the inner circumferential surface of the sealing ring (7). The inner circumferential surface of the rubber ring (6) is provided with a third serration (63). The piston rod (2) is fixed with a plurality of connecting rods (23) located in the ventilation channel (31). The ends of each connecting rod (23) are connected to a drive ring (24). The drive ring (24) is coaxially arranged with the piston rod (2). The outer circumferential surface of the drive ring (24) is fixed with a fourth serration (241) that cooperates with the third serration (63).A limiting structure is provided between the exposed end of the piston rod (2) and the second end cap (12). When the piston rod (2) rotates in the forward direction, the rubber ring (6) is forced to expand outward through the cooperation of the third sawtooth (63) and the fourth sawtooth (241). When the rubber ring (6) expands outward, the sealing plate (71) is forced to deform and move along the axial direction of the piston rod (2) and abut against the end face of the branch pipe (34) through the cooperation of the first sawtooth (72) and the second sawtooth (62). The expansion of the rubber ring (6) also forces the outer circumferential surface of the sealing ring (7) to fit the inner circumferential surface of the housing (1). The limiting structure restricts the rotation of the piston rod (2).

2. The three-chamber piston (3) type pumping device according to claim 1, characterized in that: The piston rod (2) is provided with a core tube (22) running through it. The annular gap formed between the outer circumferential surface of the core tube (22) and the inner circumferential surface of the piston rod (2) is the intermediate cavity (20). One end of the core tube (22) extends into the first chamber (110), and the other end of the core tube (22) is exposed outside the piston rod (2). The exposed end of the core tube (22) is provided with a backflush tube and a pressure sensor.

3. The three-chamber piston (3) type pumping device according to claim 1, characterized in that: The drive ring (24) has a fifth sawtooth (242) fixed on both ends, and the sealing plate (71) has a sixth sawtooth (73) on the inner diameter of the opposite side. The sixth sawtooth (73) and the first sawtooth (72) have opposite tooth surface inclination directions. The sixth sawtooth (73) and the fifth sawtooth (242) cooperate. When the rubber ring (6) forces the sealing ring (7) to expand outward, the cooperation of the sixth sawtooth (73) and the fifth sawtooth (242) will force the sealing plate (71) to deform and move along the piston rod (2) axis and abut against the end face of the branch pipe (34).

4. The three-chamber piston (3) type pumping device according to claim 1 or 3, characterized in that: The anti-rotation component includes a protrusion (341) fixed to the inner diameter of the end face of the branch pipe (34), and a limiting groove (74) provided at the inner diameter of the surface of the sealing plate (71). The depth of the limiting groove (74) is greater than the height of the protrusion (341), and the protrusion (341) is inserted into the limiting groove (74). The protrusion (341) is provided with an air injection hole (342) radially through the piston rod (2), and the air injection hole (342) is connected to the air passage (31). To maintain connectivity, the sealing sheet (71) has a switching hole (76); when the sealing sheet (71) is not deformed, the air injection hole (342) is connected to the axial gap between the sealing sheet (71) and the branch pipe (34), and the switching hole (76) is closed; when the sealing sheet (71) is deformed and abuts against the end face of the branch pipe (34), the air injection hole (342) is connected to the gap between the sealing ring (7) and the rubber ring (6) through the switching hole (76).

Images