Fluid end and plunger pump

Abstract

The invention discloses a fluid end and a plunger pump, and relates to the field of oil and gas equipment. A fluid end comprises a valve box, a first sealing ring, a packing assembly and a plunger. The valve box is provided with a first channel; the packing assembly is provided with a second channel; the first channel is connected with the second channel, and the two ends of the first sealing ring are connected with the first channel and the second channel in a sealed mode respectively. The problem that the valve box is scrapped due to damage of the packing cavity can be solved.

Description

Technical Field

[0001] This application belongs to the technical field of oil and gas equipment, specifically relating to a hydraulic end and plunger pump. Background Technology

[0002] In the development of oil and gas fields, fracturing is the main method for reservoir stimulation and production enhancement. The construction process is mainly achieved through fracturing pump equipment, which injects high-pressure, high-volume fracturing fluid into the oil and gas reservoir to break up the formation, squeeze proppant into the fractures, form artificial fractures and diversion channels, and improve oil and gas recovery rate.

[0003] As a crucial component of fracturing equipment and fracturing plunger pumps, the hydraulic end is subjected to high-pressure alternating loads and continuous erosion by proppant-carrying fracturing fluid during operation. This leads to fatigue cracking or wear in the hydraulic end valve box. Under the high-pressure alternating loads and erosion effects of the medium, the main failure sites of the hydraulic end are concentrated at the packing cavity seal, making it prone to wear or erosion pits. Especially with the further development of unconventional oil and gas, the pressure and displacement requirements of fracturing operations are constantly increasing. Furthermore, because the packing box and valve box are integrated, damage to the packing can render the entire valve box unusable, necessitating repair or scrapping of the hydraulic end. Summary of the Invention

[0004] The purpose of this application is to provide a hydraulic end and plunger pump that can solve problems such as the failure of the entire valve box due to packing box damage.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows: This application provides a hydraulic end, including: a valve box, a first sealing ring, a packing assembly, and a plunger; The valve box is provided with a first channel; The packing assembly is provided with a second channel; The first channel is connected to the second channel, and the two ends of the first sealing ring are respectively sealed to the first channel and the second channel.

[0006] This application also provides a plunger pump, including the hydraulic end described above.

[0007] In this embodiment, the first sealing ring provides a seal at the first channel to prevent fluid leakage; furthermore, the first sealing ring also provides a seal at the second channel to prevent fluid leakage. Compared to the integrated structure of the valve box and packing assembly in related technologies, the packing assembly and valve box in this embodiment are separate. When the packing assembly is damaged, it can be repaired or replaced individually without repairing or replacing the valve box, thus reducing the difficulty and cost of repair or replacement. Furthermore, the first sealing ring ensures a tight seal between the packing assembly and the valve box, preventing fluid leakage. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the first type of hydraulic end disclosed in the embodiments of this application; Figure 2 This is a cross-sectional view of the first type of packing box disclosed in the embodiments of this application; Figure 3 This is a cross-sectional view of the first sealing ring of the first form disclosed in the embodiments of this application; Figure 4 This is a cross-sectional view of the second form of the hydraulic end disclosed in the embodiments of this application; Figure 5 This is a cross-sectional view of the second type of packing box disclosed in the embodiments of this application; Figure 6 This is a cross-sectional view of the first sealing ring in the second form disclosed in the embodiments of this application; Figure 7 This is a cross-sectional view of the third type of hydraulic end disclosed in the embodiments of this application; Figure 8 This is a cross-sectional view of the third type of packing box disclosed in the embodiments of this application; Figure 9 This is a cross-sectional view of the third type of first sealing ring disclosed in the embodiments of this application; Figure 10 This is a cross-sectional view of the fourth type of hydraulic end disclosed in the embodiments of this application; Figure 11 This is a cross-sectional view of the fourth type of packing box disclosed in the embodiments of this application; Figure 12 This is a cross-sectional view of the fourth type of first sealing ring disclosed in the embodiments of this application; Figure 13 This is a cross-sectional view of the fifth type of hydraulic end disclosed in the embodiments of this application; Figure 14 This is a cross-sectional view of the fifth type of packing box disclosed in the embodiments of this application; Figure 15 This is a cross-sectional view of the fifth type of first sealing ring disclosed in the embodiments of this application; Figure 16 This is a cross-sectional view of the fifth type of second sealing ring disclosed in the embodiments of this application; Figure 17 This is a cross-sectional view of the sixth form of hydraulic end disclosed in the embodiments of this application; Figure 18 This is a cross-sectional view of the sixth type of packing box disclosed in the embodiments of this application; Figure 19 This is a cross-sectional view of the sixth form of the first sealing ring disclosed in the embodiments of this application; Figure 20 This is a schematic diagram of the hydraulic end structure disclosed in the embodiments of this application; Figure 21 This is a schematic diagram of the valve box structure disclosed in the embodiments of this application.

[0009] Explanation of reference numerals in the attached figures: 10-Valve box; 11-First channel; 12-Mounting slot; 21-First sealing ring; 211-First ring portion; 2111-Inclined surface; 212-Second ring portion; 213-Annular protrusion; 22-Second sealing ring; 221-Limiting protrusion; 30 - Packing assembly; 31 - Packing box; 311 - Second channel; 312 - First annular groove; 313 - Second annular groove; 32 - Packing body; 40-plunger; 50-Valve component; 60-Upper valve component. Detailed Implementation

[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0011] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0012] The embodiments of this application will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.

[0013] refer to Figures 1 to 21 This application discloses a hydraulic end, which includes a valve box 10, a first sealing ring 21, and a packing assembly 30.

[0014] The valve box 10 is a basic component that provides a support and mounting base for components such as the first sealing ring 21 and the packing assembly 30. The valve box 10 is provided with a first channel 11, which provides a space for the plunger 40 to reciprocate.

[0015] The packing assembly 30 is provided with a second channel 311, and the second channel 311 is connected to the first channel 11 so that the plunger 40 can reciprocate.

[0016] Optionally, the packing assembly 30 may include a packing box 31 and a packing body 32. The packing box 31 is provided with a second channel 311, which communicates with the first channel 11. The plunger 40 is movably disposed in the first channel 11 and the second channel 311, so that the plunger 40 can reciprocate within the first channel 11 and the second channel 311, thereby pressurizing the fluid in the valve box 10. The packing body 32 is sealed between the plunger 40 and the second channel 311 to ensure the sealing between the outer wall of the plunger 40 and the inner wall of the second channel 311, effectively mitigating the fluid leakage problem.

[0017] The two ends of the first sealing ring 21 are respectively sealed to the first channel 11 and the second channel 311. Based on the above configuration, the first sealing ring 21 can play a sealing role at the connection between the first channel 11 and the second channel 311 to prevent fluid leakage.

[0018] Compared to the integrated structure of valve box 10 and packing assembly 30 in related technologies, the packing assembly 30 and valve box 10 in this embodiment are separate. When the packing assembly 30 is damaged, it can be repaired or replaced separately without repairing or replacing the valve box 10, thereby reducing the difficulty and cost of repair or replacement. In addition, the first sealing ring 21 can ensure the sealing between the packing assembly 30 and valve box 10 and prevent fluid leakage.

[0019] In this embodiment, the first channel 11 provided in the valve box 10 and the second channel 311 provided in the packing box 31 provide space for the plunger 40 to reciprocate, so as to pressurize the fluid in the valve box 10 during the reciprocating movement of the plunger 40; the packing body 32 can play a sealing role between the plunger 40 and the packing box 31; the first sealing ring 21 can play a supporting role for the packing box 31, and can also play a sealing role between the packing box 31 and the valve box 10 to prevent fluid leakage.

[0020] In some embodiments, the first sealing ring 21 may be interference-fitted with the inner or outer circumferential surface of the first channel 11 to ensure the sealing between the first sealing ring 21 and the first channel 11.

[0021] The first sealing ring 21 can be interference-fitted with the inner or outer circumferential surface of the second channel to ensure the sealing between the first sealing ring 21 and the second channel 311.

[0022] In addition, the first sealing ring 21 can be metal-sealed with the first channel 11 and the second channel 311.

[0023] The specific connection method between the first sealing ring 21 and the first channel 11 and the second channel 311 will be described in detail below: In some embodiments, one end of the first sealing ring 21 along the axial direction may have a first ring portion 211, which is inserted into the first channel 11, and the outer peripheral surface of the first ring portion 211 is press-fitted with the inner peripheral surface of the first channel 11. Thus, the first ring portion 211 can provide a sealing effect at the first channel 11, ensuring the sealing between the plunger 40 and the valve box 10, and preventing fluid leakage between the outer wall of the plunger 40 and the inner wall of the first channel 11. Optionally, there may be a gap between the inner ring surface of the first sealing ring 21 and the outer wall of the plunger 40 to prevent wear of the first sealing ring 21 caused by the reciprocating movement of the plunger 40.

[0024] The other end of the first sealing ring 21 along the axial direction is press-fitted with the inner or outer circumferential surface of the second channel 311 to achieve a good seal between the other end of the first sealing ring 21 and the packing assembly 30.

[0025] In some embodiments, one of the packing assembly 30 and the first sealing ring 21 may have a second ring portion 212 at the other end along the axial direction, and the other may have a first annular groove 312, with the outer peripheral surface of the second ring portion 212 and the inner peripheral surface of the first annular groove 312 being interference-fitted.

[0026] Based on the above configuration, the first sealing ring 21 can be stably installed on the packing assembly 30 by cooperating with the second ring 212 and the first annular groove 312, so as to prevent the packing assembly 30 from moving arbitrarily in the radial direction and improve the installation stability of the packing assembly 30; in addition, the contact area between the packing assembly and the first sealing ring 21 can be increased, which is beneficial to improving the sealing performance between the two.

[0027] Optionally, the second ring portion 212 may be provided in the end region of the first sealing ring 21, and correspondingly, the first annular groove 312 may be provided in the end region of the second channel 311 of the packing box 31; or, the second ring portion 212 may be provided in the end region of the packing box 31, and the first annular groove 312 may be provided in the end region of the inner cavity of the first sealing ring 21.

[0028] In some embodiments, the outer peripheral surface of the first sealing ring 21 along the radial direction may be provided with an annular protrusion 213; correspondingly, the side of the valve box 10 may be provided with a mounting groove 12, and at least a portion of the annular protrusion 213 is embedded in the mounting groove 12. In this way, the installation between the first sealing ring 21 and the valve box 10 can be realized, and the installation stability of the first sealing ring 21 can be guaranteed.

[0029] Optionally, the mounting groove 12 can be coaxially arranged with the first channel 11, and the first channel 11 is formed at the bottom of the mounting groove 12.

[0030] Furthermore, the packing assembly 30 abuts against the axial end face of the annular protrusion 213, so that the annular protrusion 213 can axially limit the packing assembly 30 and provide a certain degree of sealing between the packing assembly 30 and the annular protrusion 213.

[0031] In other embodiments, the packing assembly 30 may also directly abut against the side of the valve box 10.

[0032] Optionally, the end of the packing assembly 30 may be located within the mounting groove 12. In this way, the mounting groove 12 can play a certain radial limiting role for the packing assembly 30, thereby improving the installation stability of the packing assembly 30. Of course, the end of the packing assembly 30 may also be located outside the mounting groove 12, which is not specifically limited here.

[0033] Optionally, the inner annular surface of the second ring portion 212 and the outer wall surface of the plunger 40 can be radially spaced to provide accommodating space for installing other structures.

[0034] In some embodiments, the valve box 10 may have a mounting groove 12 on its side. One axial end of the packing assembly 30 may be embedded in the mounting groove 12 and sleeved on the outside of the other end of the first sealing ring 21. Based on this, the mounting groove 12 can provide radial limiting for the packing assembly 30, thereby improving the installation stability of the packing assembly. Furthermore, the other end of the first sealing ring 21 can provide a sealing effect between the packing assembly and the plunger 40, thereby mitigating fluid leakage.

[0035] In some embodiments, the hydraulic end may further include a second sealing ring 22, which is disposed in the first channel 11, and at least a portion of the second sealing ring 22 is sleeved on the outside of the first sealing ring 21. One axial end of the second sealing ring 22 abuts against the packing assembly 30. Based on this arrangement, the cooperation between the second sealing ring 22 and the first sealing ring 21 can limit the plunger 40 and the packing assembly 30 in the radial direction, preventing the plunger 40 from shaking and improving the installation stability of the packing assembly 30. Furthermore, the second sealing ring 22 can also axially connect with the packing assembly 30, further improving the sealing performance between the packing assembly 30 and the second sealing ring 22.

[0036] Furthermore, the other end of the second sealing ring 22 away from the packing assembly 30 may be provided with a limiting protrusion 221, which protrudes inward toward the centerline of the second sealing ring 22; the end face of the first ring portion 211 and the outer peripheral surface are provided with an inclined surface 2111, which abuts against the surface of the limiting protrusion 221 toward the centerline. Based on this, the limiting protrusion 221 can limit the first sealing ring 21 in both the axial and radial directions to ensure the installation stability of the first sealing ring 21.

[0037] Optionally, the inner surface of the limiting protrusion 221 (i.e., the surface facing the center line) may also be provided with an inclined surface that matches the inclined surface of the first ring portion 211 to increase the contact area and improve the limiting effect on the first sealing ring 21.

[0038] In some embodiments, the side of the valve box 10 may be provided with a mounting groove 12, and one end of the first sealing ring 21 is embedded in the mounting groove 12; correspondingly, the end face of the packing assembly 30 facing the valve box 10 may be provided with a second annular groove 313, and the other end of the first sealing ring 21 is embedded in the second annular groove 313, and the end face of the packing assembly 30 abuts against the side of the valve box 10.

[0039] Based on the above settings, the first sealing ring 21 can play a role in the installation and radial limiting of the packing assembly 30, thereby improving the installation stability of the packing assembly 30. Furthermore, the contact between the end face of the packing assembly 30 and the side of the valve box 10 can play a role in the axial limiting of the packing assembly 30 and improve the sealing performance.

[0040] In some embodiments, the side of the valve box 10 may be provided with a mounting groove 12, the bottom of which may be provided with a recessed groove. A first sealing ring 21 is embedded in the recessed groove, and one end of the packing assembly 30 is embedded in the mounting groove 12 and abuts against the first sealing ring 21. Based on this arrangement, the first sealing ring 21 can seal between the valve box 10 and the packing assembly 30, thereby improving the sealing performance between the valve box 10 and the packing box 31.

[0041] The packing assembly 30 may include a packing box 31 and a packing body 32 disposed within the packing box 31. The inner wall of the packing box 31 may be provided with a first annular recessed groove, and the packing body 32 is embedded in the first annular recessed groove. In this way, the packing box 31 can be used to install and limit the packing body 32, and the packing body 32 can be used to seal between the packing box 31 and the plunger 40.

[0042] In some embodiments, one end of the first sealing ring 21 along the axial direction may be provided with a first ring portion 211, which is provided in the first channel 11 and is used to seal between the outer wall of the plunger 40 and the inner wall of the first channel 11. The other end of the first sealing ring 21 along the axial direction passes through the second channel 311. The inner wall of the first sealing ring 21 is provided with a second annular recessed groove, and the disc body 32 is embedded in the second annular recessed groove.

[0043] Based on the above configuration, the first sealing ring 21 can play a sealing role between the packing box 31 and the valve box 10, thereby improving the sealing performance between the valve box 10 and the packing box 31. In addition, the first sealing ring 21 can also play a role in installing and limiting the packing body 32, and the packing body 32 can play a sealing role between the first sealing ring 21 and the plunger 40.

[0044] Optionally, the outer circumferential surface of the first sealing ring 21 at one end along the axial direction can be a cylindrical surface or a conical surface.

[0045] In some embodiments, the packing box 31 can be connected to at least one of the valve box 10 and the first sealing ring 21 via fasteners. Optionally, the fasteners can be fastening screws, fastening bolts, clamps, or other similar structures.

[0046] Optionally, one end of the packing body 32 can be limited by the packing cap, and the other end of the packing body 32 can abut against the valve box 10 or the first sealing ring 21. In this way, the stability of the packing body 32 can be guaranteed, so that the packing body 32 will not move with the plunger 40.

[0047] In some embodiments, the outer ring surface of the first sealing ring 21 and the inner wall of the first channel 11 can be sealed together by a sealing ring to ensure the sealing between the first sealing ring 21 and the valve box 10.

[0048] In addition, the outer ring surface of the first sealing ring 21 and the inner wall of the second channel 311 can be sealed together by a sealing ring to ensure the sealing between the first sealing ring 21 and the packing box 31.

[0049] Of course, a combination of the two methods mentioned above can also be used to achieve a sealing effect.

[0050] Based on the above settings, this application provides various implementation methods, as follows: First implementation method: like Figures 1 to 3 As shown, the first sealing ring 21 can be a cylindrical structure. The first ring portion 211 of the first sealing ring 21 is located between the inner circumferential surface of the first channel 11 and the outer wall of the plunger 40 at one end along the axial direction. The other end of the first sealing ring 21 is located between the inner circumferential surface of the second channel 311 and the plunger 40. In this way, the first sealing ring 21 can play a sealing role between the plunger 40 and the valve box 10, and also between the plunger 40 and the packing box 31.

[0051] Furthermore, the side of the valve box 10 may be provided with an installation groove 12, and the first channel 11 is opened at the bottom of the installation groove 12; the end of the packing box 31 is embedded in the installation groove 12 so as to limit the end of the packing box 31 through the installation groove 12, thereby improving the installation stability of the packing box 31.

[0052] Of course, in some other embodiments, the valve box 10 may not have the mounting groove 12 provided, but instead a groove is provided on the end face of the packing box 31.

[0053] Second implementation method: like Figures 4 to 6 As shown, the outer circumferential surface of the first sealing ring 21 is provided with an annular protrusion 213, which protrudes radially from the first ring portion 211. The first ring portion 211 is located between the inner circumferential surface of the first channel 11 and the plunger 40, and the annular protrusion 213 is partially embedded axially in the mounting groove 12. Based on this, the first ring portion 211 can provide a sealing effect between the plunger 40 and the valve box 10, and the cooperation between the annular protrusion 213 and the mounting groove 12 can ensure the installation stability between the first sealing ring 21 and the valve box 10.

[0054] In addition, the first sealing ring 21 has a first annular groove 312 on its inner annular surface at the end opposite to the first ring portion 211. Correspondingly, the packing box 31 has a second ring portion 212 in the area near the second channel 311 at the shaft end. The second ring portion 212 is inserted into the first annular groove. In this way, a stable installation between the packing box 31 and the first sealing ring 21 can be achieved, and the installation stability of the packing box 31 can be improved.

[0055] The third implementation method: like Figures 7 to 9 As shown, the outer circumferential surface of the first sealing ring 21 is provided with an annular protrusion 213, which protrudes radially from the first ring portion 211. The first ring portion 211 is located between the inner wall of the first channel 11 and the plunger 40, and the annular protrusion 213 is partially embedded axially in the mounting groove 12. Based on this, the first ring portion 211 can provide a seal between the plunger 40 and the valve box 10, and the cooperation between the annular protrusion 213 and the mounting groove 12 ensures the installation stability between the first sealing ring 21 and the valve box 10.

[0056] In addition, a second ring portion 212 may be provided at the end of the first sealing ring 21 away from the first ring portion 211 and in the area close to the inner ring surface. Correspondingly, a first annular groove 312 may be provided at the shaft end of the packing box 31 and in the area close to the second channel 311. The second ring portion 212 is inserted into the first annular groove. In this way, a stable installation between the packing box 31 and the first sealing ring 21 can be achieved, and the installation stability of the packing box 31 can be improved.

[0057] Fourth implementation method: like Figures 10 to 12 As shown, the first sealing ring 21 has a circular structure; the side of the valve box 10 is provided with a mounting groove 12, and the mounting groove 12 and the first channel 11 are radially spaced apart. In this way, when the first sealing ring 21 is partially embedded in the mounting groove 12, the first sealing ring 21 surrounds the outer periphery of the first channel 11, thereby achieving a stable installation between the first sealing ring 21 and the valve box 10.

[0058] Furthermore, a second ring portion 212 is provided at the shaft end of the packing box 31 near the second channel 311. The second ring portion 212 is inserted into the inner ring cavity of the first sealing ring 21. This allows for stable installation between the packing box 31 and the first sealing ring 21, improving the installation stability of the packing box 31. In addition, the end face of the second ring portion 212 can also abut against the side of the valve box 10, thereby improving the installation stability of the packing box 31 and enhancing the sealing performance between the packing box 31 and the valve box 10.

[0059] Fifth implementation method: like Figures 13 to 16As shown, the hydraulic end includes a first sealing ring 21 and a second sealing ring 22. The first sealing ring 21 can have the same structure as the sealing ring in the first embodiment, which will not be described again here. The second sealing ring 22 is disposed between the first sealing ring 21 and the first channel 11 of the valve box 10. The second sealing ring 22 also limits the shaft end of the first sealing ring 21 through the limiting protrusion 221 at its end, so as to prevent the first sealing ring 21 from moving arbitrarily in the first channel 11 and to ensure the axial stability of the first sealing ring 21.

[0060] In addition, part of the shaft end of the packing box 31 is set in the mounting groove 12 on the side of the valve box 10, and part of the shaft end of the packing box 31 is sleeved on the outside of the first sealing ring 21. Furthermore, the shaft end of the packing box 31 also abuts against the end face of the second sealing ring 22. In this way, the packing box 31 can be limited in both the radial and axial directions. At the same time, the sealing performance between the packing box 31 and the valve box 10, the first sealing ring 21 and the second sealing element can be improved.

[0061] Sixth implementation method: like Figures 17 to 19 As shown, compared with the second embodiment described above, the axial dimension of the annular protrusion 213 in this embodiment is smaller, so that the annular protrusion 213 is completely located in the mounting groove 12 on the side of the valve box 10, and the partial shaft end of the packing box 31 is also located in the mounting groove 12. In this way, the installation stability of the packing box 31 and the sealing performance between the packing box 31 and the valve box 10 and the first sealing ring 21 can also be guaranteed.

[0062] In addition to the six methods mentioned above, valve box 10, packing box 31, first sealing ring 21 and second sealing ring 22 can also be installed in other ways, which are not specifically limited here.

[0063] The hydraulic end in this embodiment may also include an upper valve assembly 60, a lower valve assembly 50, and other structures. During operation, the power end drives the plunger 40 to reciprocate. As the plunger 40 moves outward relative to the first channel 11, the volume within the first channel 11 increases. At this time, the lower valve assembly 50 opens, allowing fluid to be drawn into the valve box 10. When the plunger 40 moves inward relative to the first channel 11, the volume within the first channel 11 decreases, thereby pressurizing the fluid. The upper valve assembly 60 then opens to discharge the pressurized fluid.

[0064] Based on the aforementioned hydraulic end, this application also discloses a plunger pump, which includes the hydraulic end. In addition, the plunger pump may also include a power end, which drives the hydraulic end to operate.

[0065] It should be noted that the specific structure and working principle of the power end can be referenced from existing technologies, and will not be elaborated here.

[0066] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A fluid end characterized by, The utility model relates to a valve box (10), a first sealing ring (21) and a packing assembly (30). The valve box (10) is provided with a first channel (11). The packing assembly (30) is provided with a second channel (311). The first channel (11) is connected with the second channel (311), and two ends of the first sealing ring (21) are respectively in sealing connection with the first channel (11) and the second channel (311). The first sealing ring (21) is in interference fit with the inner circumferential surface or the outer circumferential surface of the first channel (11).

2. The fluid end of claim 1, wherein, The first sealing ring (21) is in interference fit with the inner circumferential surface or the outer circumferential surface of the second channel (311).

3. The fluid end of claim 1, wherein, The first sealing ring (21) is in metal sealing between the first channel (11) and the second channel (311).

4. The fluid end of claim 1, wherein, A sealing ring is arranged on the sealing surface of the first channel (11) and / or the second channel (311).

5. The fluid end of any one of claims 1 to 4, wherein, The first sealing ring (21) is provided with a first ring portion (211) at one end in the axial direction, the first ring portion (211) is inserted into the first channel (11), and the outer circumferential surface of the first ring portion (211) is in interference fit with the inner circumferential surface of the first channel (11). The other end of the first sealing ring (21) in the axial direction is in interference fit with the inner circumferential surface or the outer circumferential surface of the second channel (311).

6. The fluid end of any one of claims 1 to 4, wherein, The packing assembly (30) and one of the first sealing ring (21) are provided with a second ring portion (212), and the other is provided with a first annular groove (312). The outer circumferential surface of the second ring portion (212) is in interference fit with the inner circumferential surface of the first annular groove (312).

7. The fluid end of claim 6, wherein, The outer circumferential surface of the first sealing ring (21) in the radial direction is provided with an annular protrusion (213). The side surface of the valve box (10) is provided with a mounting groove (12), and at least part of the annular protrusion (213) is embedded in the mounting groove (12).

8. The fluid end of claim 7, wherein, The end surface of the packing assembly (30) and the annular protrusion (213) in the axial direction abuts. The end of the packing assembly (30) is located inside or outside the mounting groove (12). The side surface of the valve box (10) is provided with a mounting groove (12), one end of the packing assembly (30) in the axial direction is embedded in the mounting groove (12), and the other end of the first sealing ring (21) is embedded outside.

9. The fluid end of claim 8, wherein, The hydraulic end further comprises a second sealing ring (22), the second sealing ring (22) is arranged in the first channel (11), at least part of the second sealing ring (22) is embedded outside the first sealing ring (21), and one end of the second sealing ring (22) in the axial direction abuts with the packing assembly (30).

10. The fluid end of claim 6, wherein, The other end of the second sealing ring (22) away from the packing assembly (30) is provided with a limiting protrusion (221), the limiting protrusion (221) is concave towards the center line of the second sealing ring (22).

11. The fluid end of claim 10, wherein, ​ 12. The fluid end of claim 11, wherein, ​ An inclined surface (2111) is arranged at the connection between the end surface and the outer peripheral surface of the first ring part (211), and the inclined surface (2111) abuts against the surface of the limiting protrusion (221) facing the center line.

13. The fluid end of claim 10, wherein, The fluid end further comprises a second sealing ring (22), which is arranged in the first channel (11) and at least partially sleeved outside the first sealing ring (21), and one end of the second sealing ring (22) abuts against the valve box (10) in the axial direction.

14. The fluid end of any one of claims 1-4, wherein, One end of the first sealing ring (21) is embedded in the mounting groove (12) arranged on the side surface of the valve box (10). The other end of the first sealing ring (21) is embedded in the second annular groove (313) arranged on the end surface of the packing assembly (30) facing the valve box (10), and the end surface of the packing assembly (30) abuts against the side surface of the valve box (10).

15. The fluid end of any one of claims 1 to 4, wherein, The side surface of the valve box (10) is provided with a mounting groove (12), and the groove bottom of the mounting groove (12) is provided with a sunken groove. The first sealing ring (21) is embedded in the sunken groove, and one end of the packing assembly (30) is embedded in the mounting groove (12) and abuts against the first sealing ring (21). The packing assembly (30) comprises a packing box (31) and a packing body (32) arranged in the packing box (31), and the inner wall of the packing box (31) is provided with a first annular recessed groove, and the packing body (32) is embedded in the first annular recessed groove.

16. The fluid end of any one of claims 1 to 4, wherein, One end of the first sealing ring (21) in the axial direction is provided with a first ring part (211), which is arranged in the first channel (11) and used for sealing the space between the outer wall of the plunger (40) and the inner wall of the first channel (11), and the other end of the first sealing ring (21) in the axial direction is arranged in the second channel (311). The inner wall of the first sealing ring (21) is provided with a second annular recessed groove, and the packing assembly (30) comprises a packing body (32), which is embedded in the second annular recessed groove.

17. A piston pump characterized in that The fluid end comprises the packing assembly (30) and the valve box (10). The fluid end comprises the packing assembly (30) and the valve box (10).

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