A piston assembly, a lower cylinder block structure and a pneumatic plunger pump

Abstract

The present disclosure relates to a piston assembly, a lower cylinder block structure, and a pneumatic piston pump. The piston assembly includes a hollow piston column, an upper locking member sleeved outside the piston column, a lower locking member, and a blocking member and a first sealing ring fixed between the upper locking member and the lower locking member; wherein, the blocking member is provided with a ring-shaped first installation groove with an opening facing the outer peripheral side, and the first sealing ring is arranged in the first installation groove; a ring-shaped second installation groove is formed on the outer peripheral side of at least one of the upper locking member and the lower locking member, and a second sealing ring is arranged in the second installation groove; the material stiffness of the blocking member is greater than that of the first sealing ring. The arrangement of the first sealing ring and the second sealing ring of the piston assembly is beneficial to improving the sealing between the piston assembly and the structure on its outer peripheral side, thereby reducing the entry of materials into the outer peripheral side of the piston assembly, reducing the wear of the piston assembly during use, and being beneficial to improving the service life of the piston.

Description

Technical Field

[0001] The present invention relates to the technical field of plunger pumps, and particularly to a piston assembly, a lower cylinder block structure, and a pneumatic plunger pump. Background Art

[0002] Pneumatic plunger pumps are commonly used to pump liquid materials or liquid materials with solid particles out of a material cylinder. The piston assembly is a common structure in pneumatic plunger pumps. It can be arranged inside the pump and can move relative to the inner wall of the pump inside the pump. If the material contains a large amount of high-hardness solid fillers, over time, the solid fillers are likely to have an adverse effect on the piston assembly. Summary of the Invention

[0003] A first aspect of the present invention provides a piston assembly. The piston assembly includes a hollow piston column, an upper locking member sleeved outside the piston column, a lower locking member, and a blocking member and a first sealing ring fixed between the upper locking member and the lower locking member. Wherein, the blocking member is provided with a ring-shaped first installation groove with an opening facing the outer peripheral side, and the first sealing ring is arranged in the first installation groove. A ring-shaped second installation groove is formed on the outer peripheral side of at least one of the upper locking member and the lower locking member, and a second sealing ring is arranged in the second installation groove. The material stiffness of the blocking member is greater than that of the first sealing ring.

[0004] Optionally, the height of the first sealing ring near the piston column is less than the height of the first sealing ring at the outer peripheral side.

[0005] Optionally, in the radial direction of the first sealing ring, the height of the first sealing ring gradually increases from inside to outside.

[0006] Optionally, the first sealing ring is a trapezoidal sealing ring.

[0007] Optionally, the second sealing ring is an O-ring.

[0008] Optionally, the piston column and the lower locking member are integrally formed.

[0009] Optionally, the blocking member includes a first blocking member in the middle, a second blocking member above the first blocking member, and a third blocking member below the first blocking member. The upper end of the second blocking member abuts against the upper locking member, the second blocking member abuts against the lower locking member, the first blocking member and the second blocking member form a first installation groove, and the first blocking member and the third blocking member form another first installation groove.

[0010] The second aspect of the present invention provides a lower cylinder block structure, which includes a cylinder block, a lifting rod arranged in the cylinder block, a feeding spoon, and the piston assembly as described above; wherein, the cylinder block is provided with a feeding port and a discharging port, and the interior of the cylinder block has a first chamber, a second chamber, and a third chamber arranged in sequence along the up and down direction. The discharging port is communicated with the first chamber, and the feeding port is located at the lower end of the third chamber; the piston assembly is sleeved outside the lifting rod and can move up and down in the first chamber along with the lifting and lowering of the lifting rod. A vertically penetrating spacing space is formed between the inner wall of the piston column and the lifting rod, and the outer side of the piston assembly is attached to the inner wall of the cylinder block; the feeding spoon is connected below the lifting rod, can move up and down along with the lifting and lowering of the lifting rod, and can pass through the feeding port.

[0011] During the ascending process of the lifting rod, the bottom of the piston assembly is sealed, and the first space above the piston assembly in the first chamber is isolated from the second space below the piston assembly; the second space is communicated with the second chamber and the third chamber, and the material enters the third chamber under the action of the feeding spoon and moves upward.

[0012] During the descending process of the lifting rod, the second chamber and the third chamber are isolated, the bottom of the piston can be opened, and the spacing space is communicated with the first space, the second space, and the second chamber until the bottom of the piston is sealed.

[0013] Optionally, the lower cylinder block structure includes a connecting rod and a lower cut-off valve. The feeding spoon is arranged at the lower end of the lifting rod through the connecting rod. The lower cut-off valve is arranged in the second chamber and is sleeved outside the connecting rod in a fitting manner, and the lower cut-off valve can lift in the second chamber during the process of the connecting rod lifting and lowering along with the lifting rod; during the descending process of the lifting rod, the lower cut-off valve seals the connection between the second chamber and the third chamber, and during the ascending process of the lifting rod, the lower cut-off valve rises, enabling the second chamber to be communicated with the third chamber.

[0014] The third aspect of the present invention provides a pneumatic piston pump, which includes a driving device and the lower cylinder block structure as described above; the driving device is drivingly connected to the lifting rod and can drive the lifting and lowering of the lifting rod to convey materials through the lower cylinder block structure.

[0015] For the piston assembly, the lower cylinder block structure, and the pneumatic piston pump of the present application above; the setting of the first sealing ring and the second sealing ring in the piston assembly is beneficial to improving the seal between the piston assembly and the structure on its outer peripheral side, thereby reducing the entry of materials into the outer peripheral side of the piston assembly, reducing the wear of the piston assembly during use, and being beneficial to improving the service life of the piston. Description of the Drawings

[0016] Figure 1 is a schematic structural view of a pneumatic plunger pump according to an exemplary embodiment of the present application;

[0017] Figure 2 is a three-dimensional structural view of a lower cylinder block structure according to an exemplary embodiment of the present application;

[0018] Figure 3 is Figure 2 a side view of the lower cylinder block structure shown;

[0019] Figure 4 is along Figure 3 a cross-sectional view of the lower cylinder block structure taken along the A-A section line shown;

[0020] Figure 5 is Figure 4 an enlarged view of part B of the lower cylinder block structure shown;

[0021] Figure 6 is Figure 4 an enlarged view of part C of the lower cylinder block structure shown;

[0022] Figure 7 is an exploded view of a piston assembly according to an exemplary embodiment of the present application;

[0023] Figure 8 is an exploded view of a lower cut-off valve according to an exemplary embodiment of the present application;

[0024] Figure 9 is a three-dimensional view of the cooperation between a lower cut-off valve and a valve seat according to an exemplary embodiment of the present application;

[0025] Figure 10 is a cross-sectional view of the cooperation between a lower cut-off valve and a valve seat according to an exemplary embodiment of the present application. Detailed implementation manners

[0026] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present invention. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0027] The terms used in the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. The singular forms "a", "the", and "said" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0028] It should be understood that the terms "first", "second", and similar terms used in the specification and claims of this application do not denote any order, quantity, or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "an" do not denote a quantity limitation, but rather indicate the presence of at least one. Unless otherwise indicated, terms such as "front", "rear", "lower", and / or "upper", "above", "below", "left", "right", etc. are for ease of description only and are not limited to a single position or a spatial orientation. The terms "comprising" or "including" and similar terms are intended to mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalents, and do not exclude other elements or items. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections, and may include electrical connections, whether direct or indirect.

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the case of no conflict, the features in the following embodiments and implementation manners may be combined with each other.

[0030] Figure 1 is a schematic structural diagram of a pneumatic plunger pump 1000 according to an exemplary embodiment of the present application. Please refer to Figure 1 and, if necessary, in conjunction with Figures 2 to 10 as shown. The pneumatic plunger pump 1000 can be used to pump liquid materials or liquid materials with solid particles out of the material cylinder, for example, it can be used to pump silica gel containing metal particles out of the packaging cylinder of silica gel.

[0031] The pneumatic piston pump 1000 includes a lower cylinder structure 100, a cross beam 300, a drive rod 400, a connecting rod 500, a support plate 600, a wheel disc 700, and a sleeve rod 800. The wheel disc 700 is fixedly connected to the lower end of the lower cylinder structure 100. The sleeve rods 800 are fixed to opposite sides of the support plate 600. The drive rod 400 is vertically movable and disposed within the sleeve rod 800. The cross beam 300 is disposed at the upper end of the drive rod 400 and can move up and down with the drive rod 400. The lower cylinder structure 100 is fixed below the cross beam 300 through the connecting rod 500, so that the lower cylinder structure 100 and the wheel disc 700 can move up and down with the cross beam 300. During the use of the pneumatic piston pump 1000, a material cylinder is disposed on the support plate 600, and the wheel disc 700 is inserted into the material cylinder and can be attached to the inner wall of the material cylinder and can move up and down relative to the inner wall of the material cylinder to move up and down to a corresponding position according to the amount of material in the material cylinder.

[0032] The pneumatic piston pump 1000 further includes a drive device 200. The drive device 200 is disposed at the upper end of the lower cylinder structure 100 and is used for drivingly connecting with a lifting structure within the lower cylinder structure 100 to drive the corresponding lifting structure to move up and down. The drive device 200 is a pneumatic drive device, such as a pneumatic motor.

[0033] The lower cylinder structure 100 includes a cylinder body 10, a lifting rod 60 disposed within the cylinder body 10, a feeding spoon 40, and a piston assembly 20. The cylinder body 10 is provided with a feeding port 102 and a discharging port 101. The interior of the cylinder body 10 has a first chamber 11, a second chamber 12, and a third chamber 13 arranged in sequence in the vertical direction. The discharging port 101 communicates with the first chamber 11, and the feeding port 102 is located at the lower end of the third chamber 13. For example, in some embodiments, the feeding port 102 may be the lower end opening of the third chamber. The first chamber 11, the second chamber 12, and the third chamber 13 can all be formed by independent cylinder side walls or by the same cylinder side wall.

[0034] Please refer to Figure 4 As shown, in some embodiments, the first chamber 11 mentioned here can be understood as Figure 4 the internal space corresponding to the D section area on the cylinder body 10 shown, correspondingly, the second chamber 12 can be understood as Figure 4 the internal space corresponding to the E section area on the cylinder body 10 shown, and the third chamber 13 can be understood as Figure 4 the internal space corresponding to the F section area on the cylinder body 10 shown.

[0035] The piston assembly 20 is specifically disposed within the first chamber 11, and the outer side of the piston assembly 20 is attached to the inner wall of the cylinder body 10. The piston assembly 20 is sleeved outside the lifting rod 60 and can move up and down within the first chamber 11 with the lifting of the lifting rod 60. A vertically penetrating spaced space 203 is formed between the inner wall of the piston assembly 20 and the lifting rod 60.

[0036] The feeding spoon 40 is connected to the lower part of the lifting rod 60, can move up and down with the lifting and lowering of the lifting rod 60, and can pass through the feeding port 102. Specifically, the lifting rod 60 can be connected to the lower part of the driving device 200 through the upper driving rod 50. The driving device 200 specifically drives the lifting rod 60 to lift by directly driving the upper driving rod 50 to lift, so as to convey materials through the lower cylinder structure 100.

[0037] When the pneumatic piston pump 1000 works, during the ascending process of the lifting rod 60, the bottom of the piston assembly 20 is sealed, and the first space above the piston assembly 20 and the second space below the piston assembly 20 in the first chamber 11 are separated. The second space communicates with the second chamber 12 and the third chamber 13, and the material enters the third chamber 13 under the action of the feeding spoon 40 and continues to move upward as the lifting rod 60 moves upward. During the ascending process of the lifting rod 60, the material in the first space is squeezed upward and flows out from the discharge port 101.

[0038] During the descending process of the lifting rod 60, the second chamber 12 and the third chamber 13 are isolated, the bottom of the piston can be opened, and the spaced space 203 communicates with the first space, the second space, and the second chamber 12 until the bottom of the piston is sealed. Correspondingly, the upper locking member 21 includes a locking portion 211 and a through portion 212, and a through hole 2120 is formed in the through portion 212. The spaced space 203 communicates with the first space through the through hole 2120. During the descending process of the lifting rod 60, the second spaced space 203 communicates with the first space, the second space, and the second chamber 12, and the material also flows upward and can flow out from the discharge port 101. It can be seen that during the ascending and descending processes of the lifting rod 60, materials are output from the discharge port 101.

[0039] The lower cylinder structure 100 further includes a connecting rod 70 and a lower cut-off valve 30. The feeding spoon 40 is arranged at the lower end of the lifting rod 60 through the connecting rod 70. The lower cut-off valve 30 is arranged in the second chamber 12 and fits around the outside of the connecting rod 70. The lower cut-off valve 30 is subject to the frictional force of the connecting rod 70 and can rise and fall in the second chamber 12 along with the connecting rod 70 during the lifting and lowering of the connecting rod 70 with the lifting rod 60. During the descending process of the lifting rod 60, the lower cut-off valve 30 can descend to seal the connection between the second chamber 12 and the third chamber 13. During the ascending process of the lifting rod 60, the lower cut-off valve 30 can rise, enabling the second chamber 12 to communicate with the third chamber 13. A limiting wall 121 is provided at the upper part of the second chamber 12 to limit the upward movement of the lower cut-off valve 30. After the lower cut-off valve 30 rises with the connecting rod 70 and abuts against the limiting wall 121, the connecting rod 70 can continue to rise while the lower cut-off valve 30 does not continue to rise. When the lower cut-off valve 30 descends to the connection between the second chamber 12 and the third chamber 13, it is limited in this position and cannot descend, while the connecting rod 70 can continue to descend.

[0040] It should be noted that the lifting rod 60 mentioned here can be understood as a piston rod. The height of the lifting rod 60 is slightly greater than the height of the piston assembly 20. The structural dimensions of the upper and lower ends of the lifting rod 60 are relatively large. When the piston assembly 20 moves to abut against the upper end or the lower end, the upper end or the lower end can limit the up and down movement of the piston assembly 20. Under the action of the frictional force of the inner wall of the cylinder block 10 on the piston assembly 20, the piston assembly 20 can move up and down relative to the lifting rod 60. Specifically, when the lifting rod 60 starts to rise from a low position, the piston assembly 20 is subjected to the downward frictional force of the inner wall of the cylinder block 10 and can descend relative to the lifting rod 60. When the lifting rod 60 descends from a high position, the piston assembly 20 is subjected to the upward frictional force of the inner wall of the cylinder block 10 and can move upward relative to the lifting rod 60.

[0041] The lower cylinder block structure 100 may further include an upper cut-off valve (not shown). The upper cut-off valve is fixedly installed at the lower end of the lifting rod 60. During the upward movement of the lifting rod 60, the piston assembly 20 can descend relative to the lifting rod 60 until it abuts against the upper cut-off valve, thereby realizing the bottom seal of the piston assembly 20. During the downward movement of the lifting rod 60, the piston assembly 20 can move upward relative to the lifting rod 60 to separate from the upper cut-off valve, thereby realizing the communication between the spaced space 203 and the first space, the second space, and the second chamber 12. Until the upper cut-off valve abuts against the bottom of the first chamber 11 (which can also be regarded as the connection between the first chamber and the second chamber), the lower end of the piston assembly 20 abuts against the upper cut-off valve, and the bottom of the piston assembly 20 is sealed, that is, the piston assembly 20 descends to the lowest position. This is the critical state of the lifting and lowering movement of the lifting rod 60, and the lifting rod 60 will then rise.

[0042] The piston assembly 20 includes a hollow piston column 26, an upper locking member 21 sleeved outside the piston column 26, a lower locking member 22, and a blocking member and a first sealing ring 24 fixed between the upper locking member 21 and the lower locking member 22. Among them, the blocking member is provided with a ring-shaped first installation groove 201 with an opening facing the outer peripheral side, and the first sealing ring 24 is arranged in the first installation groove 201. At least one of the outer peripheral sides of the upper locking member 21 and the lower locking member 22 is provided with a ring-shaped second installation groove 202, and a second sealing ring 27 is arranged in the second installation groove 202. The material stiffness of the blocking member is greater than the material stiffness of the first sealing ring 24 to provide sufficient blocking and limiting effects on the first sealing ring 24.

[0043] It should be noted that in some embodiments, the material of the blocking member is a metal material. The outer periphery of the first sealing ring and the outer periphery of the blocking member can be located on the same cylindrical surface, or the outer periphery of the first sealing ring slightly protrudes outside the outer periphery of the blocking member to ensure the sealing performance of the first sealing ring. Similarly, the outer periphery of the second sealing ring and the outer periphery of the corresponding upper locking member 21 or the outer periphery of the lower locking member 22 can be located on the same cylindrical surface, or the outer periphery of the second sealing ring slightly protrudes outside the outer periphery of the corresponding upper locking member 21 or the outer periphery of the lower locking member 22 to ensure the sealing performance of the second sealing ring.

[0044] In some embodiments, the height of the first sealing ring 24 near the piston rod 26 is less than the height of the first sealing ring 24 at the outer peripheral side, such that the thickness of the sealing ring is larger on the side close to the inner wall of the cylinder, which is beneficial to reducing the deformation amount of the first sealing ring, thereby improving the sealing performance of the first sealing ring.

[0045] In some embodiments, in the radial direction of the first sealing ring 24, the height of the first sealing ring 24 gradually increases from the inside to the outside.

[0046] For example, in some embodiments, the first sealing ring 24 is a Figure 5 trapezoidal sealing ring as shown.

[0047] In some embodiments, the second sealing ring 27 is an O-ring.

[0048] The upper locking member 21 and the lower locking member 22 mentioned here can be locking nuts. They can be fixedly assembled with the piston rod 26 through thread fitting.

[0049] In some embodiments, the piston rod 26 and the lower locking member 22 are integrally formed. Compared with the embodiment of setting threads in the lower locking member 22 and the piston rod 26, it avoids affecting the structural strength of the piston rod 26 and the lower locking member 22 due to the setting of threads, which is beneficial to improving the structural strength of the piston assembly 20 and the sealing performance between the piston assembly 20 and the upper cutting valve.

[0050] In some embodiments, the blocking member includes a first blocking member 23 in the middle, a second blocking member 25 above the first blocking member 23, and a third blocking member 28 below the first blocking member 23; the upper end of the second blocking member 25 abuts against the upper locking member 21, the second blocking member 25 abuts against the lower locking member 22, the first blocking member 23 and the second blocking member 25 form a first installation groove 201, and the first blocking member 23 and the third blocking member 28 form another first installation groove 201.

[0051] Based on the above structure of the piston assembly, when assembling the piston assembly, it is only necessary to first sleeved the blocking member and the first sealing ring on the piston column 26 in sequence, then lock the upper locking member 21 to the upper end of the piston column 26, and then install the second sealing ring. The assembly of each fitting of the piston assembly is simple, convenient and easy to operate. For those with second installation grooves provided in both the upper locking member and the lower locking member, the second sealing rings respectively provided in the two second installation grooves can maintain the force balance of the upper and lower parts of the piston assembly with very small deformation, which is beneficial to improving the sealing performance of the piston assembly. For the embodiment provided with two first installation grooves and corresponding first sealing rings, the up-and-down balance of the piston assembly can also be well maintained, which is beneficial to improving the sealing performance of the piston assembly.

[0052] Further, the down-cut valve 30 includes an annular valve core 31 and a housing 32 provided outside the valve core 31. The housing 32 includes a first part 321 located on the outer peripheral side of the valve core 31 and a second part 322 extending inward from the upper end of the first part 321 and covering the upper part of the valve core 31. At least a part of the upper surface of the second part 322 near the center of the second part 322 forms a diversion surface 3220 that slopes outward and downward, so as to facilitate guiding the material above the down-cut valve to move outward, reducing the adverse effects brought to the down-cut valve due to the precipitation and accumulation of the material above the down-cut valve, and is beneficial to improving the service life of the down-cut valve.

[0053] In some embodiments, in the radial direction of the second part 322, the height of the diversion surface 3220 gradually decreases from inside to outside. The diversion surface 3220 can be the upper surface of a part of the structure of the second part 322 near the center, or the upper surface of the entire second part 322.

[0054] Please refer to Figures 8 to 10 As shown, in some embodiments, the diversion surface 3220 is a conical surface. Of course, the diversion surface 3220 can also be an inclined sliding surface of other shapes. For example, in the direction from the center of the second part to the outside, the diversion surface can be an arc-shaped concave surface or an arc-shaped convex surface.

[0055] In some embodiments, the valve core 31 is made of polyether ether ketone material, which is beneficial to improving the structural strength of the valve core 31 and extending the service life of the valve core 31.

[0056] In some embodiments, the housing 32 is made of a metal material, such as stainless steel, to improve the structural strength of the down-cut valve, extend the service life of the down-cut valve, reduce the leakage of the material at the down-cut valve, and is beneficial to improving the material conveying capacity of the pneumatic piston pump.

[0057] In some embodiments, an annular receiving groove 3201 with an opening inward is provided on the inner side wall of the second part 322, and a valve sealing ring 33 is provided in the receiving groove 3201.

[0058] In some embodiments, the valve core 31 includes a first annular portion 311 extending longitudinally and a second annular portion 312 extending outward from the lower end of the first annular portion 311. The housing 32 is sleeved outside the valve core 31, and the lower end of the first portion 321 abuts against the upper surface of the second annular portion 312.

[0059] The housing 32 can be specifically connected by screws 34. The screws 34 can be horizontally inserted through the first portion 321 of the housing 32 and the first annular portion 311. In addition, the outer end of the screw 34 can be welded to weld the screw 34 to the first portion 321 of the housing 32, so that the housing 32 and the valve core 31 are assembled more firmly.

[0060] Further, the cylinder block 10 is provided with a valve seat 80 at the connection of the second chamber 12 and the third chamber 13. The undercut valve 30 can specifically abut against the upper end of the valve seat 80 during the downward movement along with the connecting rod 70, so as to realize the isolation between the second chamber 12 and the third chamber 13. Correspondingly, a ring-shaped notch portion 3120 can be formed by inwardly recessing the outer peripheral side of the lower end of the valve core 31 to fit with the valve seat 80.

[0061] The above description is only the preferred embodiments of the present invention, and does not impose any formal limitations on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A piston assembly, characterized in that, the piston assembly includes a hollow piston column, an upper locking member sleeved outside the piston column, a lower locking member, and a blocking member and a first sealing ring fixed between the upper locking member and the lower locking member; wherein, the blocking member is provided with a ring-shaped first installation groove with an opening facing the outer peripheral side, and the first sealing ring is arranged in the first installation groove; a ring-shaped second installation groove is formed on the outer peripheral side of at least one of the upper locking member and the lower locking member, and a second sealing ring is arranged in the second installation groove; the material stiffness of the blocking member is greater than that of the first sealing ring; the blocking member includes a first blocking member in the middle, a second blocking member above the first blocking member, and a third blocking member below the first blocking member; the upper end of the second blocking member abuts against the upper locking member, the second blocking member abuts against the lower locking member, the first blocking member and the second blocking member form a first installation groove, and the first blocking member and the third blocking member form another first installation groove; the upper locking member includes a locking portion and a through portion, and a through hole is formed in the through portion; When assembling the piston assembly, first sleeved the blocking member and the first sealing ring on the piston column in sequence, then lock the upper locking member at the upper end of the piston column, and then install the second sealing ring.

2. The piston assembly according to claim 1, characterized in that, the height of the first sealing ring on the side close to the piston column is less than the height of the first sealing ring on the outer peripheral side.

3. The piston assembly according to claim 2, characterized in that, in the radial direction of the first sealing ring, the height of the first sealing ring gradually increases from inside to outside.

4. The piston assembly according to claim 3, characterized in that, the first sealing ring is a trapezoidal sealing ring.

5. The piston assembly according to claim 1, characterized in that, the second sealing ring is an O-shaped sealing ring.

6. The piston assembly according to claim 1, characterized in that, the piston column and the lower locking member are integrally formed.

7. A lower cylinder block structure, characterized in that, it includes a cylinder block, a lifting rod arranged in the cylinder block, a feeding spoon, and the piston assembly according to any one of claims 1 to 6; wherein, the cylinder block is provided with a feeding port and a discharging port, and the inside of the cylinder block has a first chamber, a second chamber, and a third chamber arranged in sequence in the up-down direction, the discharging port is communicated with the first chamber, and the feeding port is located at the lower end of the third chamber; the piston assembly is sleeved outside the lifting rod and can move up and down in the first chamber along with the lifting of the lifting rod, a vertically through interval space is formed between the inner wall of the piston column and the lifting rod, and the outer side of the piston assembly is attached to the inner wall of the cylinder block; the feeding spoon is connected below the lifting rod, can move up and down along with the lifting of the lifting rod, and can pass through the feeding port; During the upward movement of the lifting rod, the bottom of the piston assembly is sealed, and the first space above the piston assembly in the first chamber is isolated from the second space below the piston assembly; the second space communicates with the second chamber and the third chamber, and the material enters the third chamber under the action of the feeding spoon and moves upward. During the downward movement of the lifting rod, the second chamber and the third chamber are isolated, the bottom of the piston can be opened, and the spaced space communicates with the first space, the second space, and the second chamber until the bottom of the piston is sealed.

8. The lower cylinder structure according to claim 7, characterized in that the lower cylinder structure includes a connecting rod and a lower cut-off valve. The feeding spoon is arranged at the lower end of the lifting rod through the connecting rod. The lower cut-off valve is arranged in the second chamber and sleeved outside the connecting rod in a fitting manner, and the lower cut-off valve can move up and down in the second chamber during the up and down movement of the connecting rod following the lifting rod; during the downward movement of the lifting rod, the lower cut-off valve seals the connection between the second chamber and the third chamber, and during the upward movement of the lifting rod, the lower cut-off valve rises, enabling the second chamber to communicate with the third chamber.

9. A pneumatic piston pump, characterized in that it includes a driving device and the lower cylinder structure according to claim 7 or 8; the driving device is drivingly connected to the lifting rod and can drive the lifting of the lifting rod to convey materials through the lower cylinder structure.

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