Bottom ball seat of packer

Abstract

The bottom ball seat of the packer comprises an outer cylinder and a ball seat body, a limiting ring groove is formed in the outer cylinder, the ball seat body comprises an inner cylinder assembly and a ball core, the inner cylinder assembly is provided with a first communicating hole and a second communicating hole with the inner diameter sequentially decreasing in the axial direction, and the ball core comprises a rod body which is arranged in the second communicating hole in a sliding mode. A plurality of limiting openings and shearing holes are formed in the side wall of the inner cylinder assembly in the circumferential direction, the limiting blocks are arranged in the limiting openings, and the two ends of each limiting block abut against the corresponding limiting ring and the corresponding limiting ring groove. The rod body is provided with a connecting hole corresponding to the shearing hole, and the shearing pin is arranged in the shearing hole and connected with the connecting hole. Through cooperation of the outer cylinder body, the inner cylinder assembly, the ball core and the limiting block, only shear screws with the conventional size and number are needed in the using process, the accumulated error value of the shear pins is reduced, and meanwhile the ball seat obtains the larger drift diameter so as to meet the working requirement.

Description

Technical Field

[0001] The utility model relates to the technical field of packers, in particular to a bottom ball seat of a packer. Background Art

[0002] With the rapid development of my country's economy, people's daily life and industrial electrical equipment are increasing, and the power is also increasing. During peak electricity consumption, it is easy for electricity to fail to meet the all-weather electricity demand, resulting in industrial power restrictions and use restrictions, which has a great impact on production. Conversely, during low electricity consumption, some electricity cannot be well stored or utilized, resulting in energy waste.

[0003] In order to solve the above problems, people have developed a new compressed air storage technology through continuous exploration. This technology mainly uses a packer to seal in the underground cave to form an annulus cavity. When electricity consumption is low, the surplus electricity drives the air compressor to compress the air into the cave for storage. When electricity consumption is at a peak, the air in the cave is released to drive the turbine to generate electricity, so as to improve energy utilization.

[0004] Among them, the ball seat at the bottom of the packer is one of the important components for realizing the sealing of the packer. In the prior art, in order to obtain a larger diameter after the ball seat is sheared and pumped off to adapt to the injection and production of large-displacement compressed air, a ball seat core piston with a large cross-section is usually set. However, this method requires the setting of more shear pins, which increases the cumulative shear value error of the shear pins, resulting in incomplete sealing of the packer and a major safety hazard, or making it difficult to pump off the ball seat core, requiring drilling and grinding tools to increase operating costs and be time-consuming and labor-intensive. Utility Model Content

[0005] In view of the shortcomings of the prior art, the utility model provides a bottom ball seat of a packer, comprising:

[0006] An outer cylinder body, wherein the outer cylinder body is provided with a limiting ring groove, and the limiting ring groove is arranged circumferentially along the inner wall of the outer cylinder body; and

[0007] A ball seat is arranged in the outer cylinder body, and includes an inner cylinder assembly and a ball core. The inner cylinder assembly is provided with a first connecting hole and a second connecting hole in sequence along the axial direction, and the inner diameter of the first connecting hole is larger than the inner diameter of the second connecting hole. The ball core includes a rod body, the outer diameter of the rod body is smaller than the inner diameter of the second connecting hole, the rod body is slidably arranged in the second connecting hole, and one end of the rod body is exposed in the first connecting hole. A limiting ring is provided on the outer wall ring of one end of the rod body, and the limiting ring is slidably arranged in the first connecting hole, and the outer diameter of the limiting ring is larger than the second connecting hole. One end of the rod body also has a ball entry hole, and the ball entry hole is directly opposite to the port at one end of the first connecting hole.

[0008] The ball seat also includes multiple limit blocks and multiple shear pins. Both ends of the side wall of the inner cylinder assembly are respectively provided with multiple limit openings and multiple shear holes along the circumferential direction. The multiple limit openings are connected with the first connecting hole and are directly opposite to the limit ring groove. The limit blocks are respectively arranged in the limit openings. Both ends of each limit block are respectively abutted against the limit ring and the limit ring groove. The multiple shear holes are connected with the second connecting hole. The end of the rod body away from the limit ring is provided with multiple connecting holes corresponding to the shear holes. The multiple shear pins are respectively arranged in the multiple shear holes and fixedly connected in the connecting holes.

[0009] According to one embodiment of the utility model, a ball entrance through hole is arranged axially through the rod body, and includes a first ball entrance hole and a second ball entrance hole, wherein the first ball entrance hole is located at one end of the rod body close to the limiting ring, the inner diameter of the first ball entrance hole is larger than the inner diameter of the second ball entrance hole, and a first blocking inclined hole is connected between the first ball entrance hole and the second ball entrance hole, and the inner diameter of the first blocking inclined hole gradually decreases from the first ball entrance hole to the second ball entrance hole.

[0010] According to one embodiment of the utility model, one end of the inner cylinder assembly also has an annular guide port, which is located at the end of the first connecting hole facing away from the second connecting hole, and the inner diameter of the annular guide port gradually decreases toward the second connecting hole.

[0011] According to one embodiment of the utility model, the ball core is further provided with a second oblique sealing hole, which is provided at one end of the limiting ring facing the annular guide port, one end of which is directly opposite to the annular guide port, and the other end is connected to the first ball entrance hole. The inner diameter of the second oblique sealing hole also gradually decreases toward the second ball entrance hole, and its maximum inner diameter is equal to the minimum inner diameter of the annular guide port, and its minimum inner diameter is equal to the inner diameter of the first ball entrance hole.

[0012] According to one embodiment of the utility model, the outer cylinder body includes a first cylinder body and a second cylinder body. The inner wall of the first cylinder body is provided with a step surface, the step surface faces one end of the first cylinder body, one end of the second cylinder body is arranged in the first cylinder body and is screwed with the first cylinder body, one end of the second cylinder body is opposite to the step surface and a limiting ring groove is formed between the step surface.

[0013] According to one embodiment of the utility model, the step surface is an inclined surface, and the second cylinder is provided with a limiting inclined surface corresponding to the step surface. The step surface and the limiting inclined surface make the side walls of the limiting ring groove tilt outward on both sides thereof, and an extrusion inclined surface is provided at the end of the limiting block corresponding to the step surface and the limiting inclined surface. One end of the limiting block abuts against the limiting ring groove, and the extrusion inclined surface respectively abuts against the step surface and the limiting inclined surface.

[0014] According to one embodiment of the utility model, the inner cylinder assembly includes an inner cylinder body and a shear sleeve, the inner cylinder body is arranged in the outer cylinder body, the first connecting hole is arranged through both ends of the outer cylinder body, the annular guide port is arranged at one end of the inner cylinder body, a plurality of limit openings are arranged circumferentially on the side wall of the inner cylinder body close to the annular guide port, one end of the shear sleeve is arranged in the end of the first connecting hole facing away from the annular guide port and is screwed with the inner cylinder body, the second connecting hole is arranged through both ends of the shear sleeve, and a plurality of shear holes are arranged circumferentially on the side wall of the other end of the shear sleeve.

[0015] According to one embodiment of the utility model, both ends of the inner wall of the first cylinder are provided with a first internal thread, the outer wall of the second cylinder is provided with a first external thread, and the second cylinder is connected to the first internal thread at one end of the first cylinder through the first external thread. When in use, the first internal thread at the other end of the first cylinder can be used to connect the sealer.

[0016] According to one embodiment of the utility model, a connecting ring groove is also provided on the inner wall of the first cylinder. The connecting ring groove is provided at one end of the inner wall of the first cylinder away from the inner cylinder assembly and is located between the two first internal threads. When in use, the connecting ring groove can be used to install a pressure gauge.

[0017] The beneficial effect of the utility model is that through the cooperation of the outer cylinder body, the inner cylinder assembly, the ball core and the limit block, only the conventional size and number of shear screws need to be used during use, thereby reducing the cumulative error value of the shear pins and ensuring that the ball seat obtains a larger diameter to meet work requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 It is a schematic diagram of the explosion structure of the bottom ball seat of the packer in the embodiment;

[0020] Figure 2 A schematic diagram of the longitudinal cross-sectional structure of the bottom ball seat of the packer in the embodiment;

[0021] Figure 3 It is a schematic cross-sectional view of the outer cylinder and the inner cylinder assembly in the embodiment;

[0022] Figure 4 for Figure 2 Enlarged view of part A in the middle;

[0023] Figure 5 for Figure 2 Enlarged view of middle part B;

[0024] Figure 6 This is a schematic diagram of the ball seat structure in the embodiment;

[0025] Figure 7 for Figure 4 Schematic diagram of the explosion structure;

[0026] Figure 8 This is a schematic diagram of the cross-sectional structure of the outer cylinder in the embodiment;

[0027] Fig. 9 for Figure 8 Enlarged view of part C in the middle. DETAILED DESCRIPTION

[0028] The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. In other words, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0029] In addition, in the present utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present utility model. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0030] See also Figure 1-Figure 7 , Figure 1 It is a schematic diagram of the explosion structure of the bottom ball seat of the packer in the embodiment, Figure 2 is a schematic diagram of the longitudinal cross-sectional structure of the bottom ball seat of the packer in the embodiment, Figure 3 It is a schematic cross-sectional view of the outer cylinder and the inner cylinder assembly in the embodiment. Figure 4 for Figure 2 Enlarged view of part A in the middle. Figure 5 for Figure 2 Enlarged view of part B in the middle. Figure 6 It is a schematic diagram of the ball seat structure in the embodiment, Figure 7 for Figure 4Schematic diagram of explosion structure. In this example, a bottom ball seat of a packer includes an outer cylinder 1 and a ball seat 2, wherein the outer cylinder 1 is provided with a limiting ring groove 13, and the limiting ring groove 13 is arranged circumferentially along the inner wall of the outer cylinder 1. The ball seat 2 is arranged in the outer cylinder 1, and includes an inner cylinder component 21 and a ball core 22. The inner cylinder component 21 is provided with a first connecting hole 2111 and a second connecting hole 2121 connected in sequence along the axial direction, and the inner diameter of the first connecting hole 2111 is larger than the inner diameter of the second connecting hole 2121. The ball core 22 includes a rod body 221, and the outer diameter of the rod body 221 is smaller than the inner diameter of the second connecting hole 2121. The rod body 221 is slidably arranged in the second connecting hole 2121, and one end of the rod body 221 is exposed in the first connecting hole 2111. A limiting ring 222 is arranged on the outer wall ring of one end of the rod body 221, and the limiting ring 222 is slidably arranged in the first connecting hole 2111, and the outer diameter of the limiting ring 222 is larger than the second connecting hole 2121. One end of the rod body 221 also has a ball entrance hole 223, and the ball entrance hole 223 is directly opposite to the port at one end of the first connecting hole 2111. The ball seat 2 also includes a plurality of limit blocks 23 and a plurality of shear pins 24. Both ends of the side wall of the inner cylinder assembly 21 are respectively provided with a plurality of limit openings 2112 and a plurality of shear holes 2122 along the circumferential direction. The plurality of limit openings 2112 are connected to the first connecting hole 2111 and directly opposite to the limit ring groove 13. The limit blocks 23 are respectively arranged in the limit openings 2112. Both ends of each limit block 23 respectively abut against the limit ring 222 and the limit ring groove 13. The plurality of shear holes 2122 are connected to the second connecting hole 2121. The end of the rod body 221 away from the limit ring 222 is provided with a plurality of connecting holes 224 corresponding to the shear holes 2122. The plurality of shear pins 24 are respectively arranged in the plurality of shear holes 2122 and fixedly connected in the connecting holes 224.

[0031] It can be understood that when the inner cylinder assembly 21 is subjected to axial thrust, the inner cylinder assembly 21 cannot be axially displaced under the restriction of the limit block 23. Similarly, under the restriction of the shear pin 24, the ball core 22 cannot be axially displaced. When the shear pin 24 is disconnected, the ball core loses the restriction of the shear pin 24, and the limit ring 222 can slide along the first connecting hole 2111 toward the second connecting hole 2121 to move away from the limit opening 2112, so that one end of the limit block 23 loses the abutment force of the limit ring 222, thereby falling into the first connecting hole 2111 from the limit opening 2112. At this time, the inner cylinder assembly 21 loses the restriction of the limit block 23 and can move axially along the outer cylinder body 1 and detach.

[0032] When in use, the outer cylinder 1 can be used to be installed on the packer. When the packer needs to be sealed, the sealing ball 0 is put into the packer. The sealing ball 0 passes through the packer and enters the ball seat 2 from the outer cylinder 1, and blocks the ball entry hole 223 so that a closed cavity is formed between the bottom ball seat and the packer. At this time, pressure is applied to the packer, and the pressure is transmitted to the ball core 22 along with the sealing ball 0, causing the ball core 22 to squeeze the shear pin 24 outward. During the process, the pressure inside the packer seals the packer. After the packer is sealed, as the pressure continues to rise, the outward squeezing force of the ball core 22 causes the shear pin 24 to break, and the rod body 221 moves outward along the second connecting hole 2121. At the same time, the limit ring 222 moves along the first connecting hole 21 11 slides toward the second connecting hole 2121 and abuts against one end of the second connecting hole 2121, and the inner tube assembly 21 is pushed outward by one end of the second connecting hole 2121. At the same time, one end of the limit block 23 loses the abutting force of the limit ring 222, and thus falls off from the limit opening 2112 to the first connecting hole 2111, so that the inner tube assembly 21 loses the restriction of the limit block 23 and detaches from the outer cylinder body 1, thereby forming a large diameter of the outer cylinder body 1, that is, the packer obtains a large diameter. In this way, in actual use, only shear screws of conventional size and number need to be used, which can reduce the cumulative error value of the shear pins and ensure that the ball seat obtains a larger diameter to meet work requirements.

[0033] Review Figure 2 Further, the ball entry hole 223 is axially penetrated through the rod body 221, and includes a first ball entry hole 2231 and a second ball entry hole 2232, wherein the first ball entry hole 2231 is located at one end of the rod body 221 close to the stop ring 222, the inner diameter of the first ball entry hole 2231 is larger than the inner diameter of the second ball entry hole 2232, and a first blocking oblique hole 2233 is connected between the first ball entry hole 2231 and the second ball entry hole 2232, and the inner diameter of the first blocking oblique hole 2233 gradually decreases from the first ball entry hole 2231 to the second ball entry hole 2232, so that its cross section forms a funnel shape. When in use, the sealing ball 0 enters through the first ball entry hole 2231 and blocks the first blocking oblique hole 2233, so that the outer surface of the sealing ball 0 can be more effectively fitted to the first blocking oblique hole 2233 to improve the sealing effect and stability.

[0034] Review Figure 2-Figure 5 Furthermore, one end of the inner cylinder assembly 21 also has an annular guide opening 2113, which is located at the end of the first communication hole 2111 facing away from the second communication hole 2111, and the inner diameter of the annular guide opening 2113 gradually decreases toward the second communication hole 2111, so that the annular guide opening 2113 is also funnel-shaped. In this way, when the sealing ball 0 passes through the annular guide opening 2113, it will enter the first ball entry hole 2231 along the inner wall of the annular guide hole 2113, ensuring that the sealing ball 0 smoothly enters the first oblique blocking hole 2233 for blocking.

[0035] Preferably, the ball core 22 is further provided with a second oblique plugging hole 2234, which is provided at one end of the stop ring 222 facing the annular guide opening 2113, one end of which is directly opposite to the annular guide opening 2113, and the other end is connected with the first ball entry hole 2233. The inner diameter of the second oblique plugging hole 2234 also gradually decreases toward the second ball entry hole 2232, and its maximum inner diameter is equal to the minimum inner diameter of the annular guide opening 2113, and its minimum inner diameter is equal to the inner diameter of the first ball entry hole 2233. Similarly, the second oblique plugging hole 2234 is also funnel-shaped. When the sealing ball 0 in the first oblique plugging hole 2233 fails and fails to seal, a large-sized sealing ball can be put into the second oblique plugging hole 2234 for plugging again, so as to ensure that the ball core 22 can be pumped out smoothly and improve the stability of product use.

[0036] See also Figure 8-Figure 9 , review Figure 1-Figure 3 , Figure 8 This is a schematic diagram of the cross-sectional structure of the outer cylinder in the embodiment, Fig. 9 for Figure 8 Specifically, the outer cylinder 1 includes a first cylinder 11 and a second cylinder 12. The inner wall of the first cylinder 11 is provided with a step surface 111, and the step surface 111 faces one end of the first cylinder 11. One end of the second cylinder 11 is arranged in the first cylinder 11 and is screwed to the first cylinder 11. One end of the second cylinder 11 is opposite to the step surface 111 and a limiting ring groove 13 is formed between the step surface 111 and the step surface 111. During installation, the second cylinder 12 can be removed from one end of the first cylinder 11 first. At this time, one end of the limit block 23 is installed in the limit opening 2112, and then the inner cylinder assembly 21 is installed in the first cylinder 11. At this time, the second cylinder 12 is inserted into one end of the first cylinder 11 and screwed with the first cylinder 11, so that the step surface 111 and one end of the second cylinder 12 form a limit ring groove 13. At this time, the two ends of the limit block 23 are respectively abutted against the limit ring 222 and the limit ring groove 13 to fix the inner cylinder assembly 21. In this way, the convenience of product installation can be effectively improved.

[0037] Among them, the step surface 111 is an inclined surface, and the second cylinder 12 is provided with a limiting inclined surface 122 corresponding to the step surface 111. The step surface 111 and the limiting inclined surface 122 make the side walls of the limiting ring groove 13 tilt outward on both sides thereof, and the end of the limiting block 23 is provided with an extrusion inclined surface 231 corresponding to the step surface 111 and the limiting inclined surface 122. One end of the limiting block 23 abuts against the limiting ring groove 13, and the extrusion inclined surface 231 abuts against the step surface 111 and the limiting inclined surface 122 respectively. In this way, it can be understood that when the limiting ring 222 moves toward the second connecting hole 2121 and pushes the inner cylinder assembly 21 outward, the limiting opening 2112 pulls the limiting block 23 outward, so that the extrusion slope 231 and the limiting slope 122 are squeezed against each other, thereby pressing the limiting block 23 from the limiting opening 2112 into the first connecting hole 2111, preventing the limiting block 23 from getting stuck in the inner cylinder assembly 21, ensuring the smooth pumping out of the inner cylinder assembly 21, and improving the stability of product use.

[0038] Preferably, in this example, both ends of the limiting block 23 are provided with extrusion inclined surfaces 231 corresponding to the step surface 111 and the limiting inclined surface 122, so that there is no need to distinguish between the front and back ends during actual installation, thereby further improving the convenience of installation.

[0039] Review Figure 1 , Figure 2 and Figure 5 Specifically, the inner cylinder assembly 21 includes an inner cylinder body 211 and a shear sleeve 212. The inner cylinder body 211 is arranged in the outer cylinder body 1, and the first connecting hole 2111 is set through both ends of the outer cylinder body 211. The annular guide port 2113 is arranged at one end of the inner cylinder body 211. A plurality of limiting openings 2112 are circumferentially arranged on the side wall of the inner cylinder body 211 close to one end of the annular guide port 2113. One end of the shear sleeve 212 is arranged in one end of the first connecting hole 2111 facing away from the annular guide port 2113 and is screwed with the inner cylinder body 211. The second connecting hole 2121 is set through both ends of the shear sleeve 212, and a plurality of shear holes 2122 are circumferentially arranged on the side wall of the other end of the shear sleeve 212. In this way, during installation, the limiting ring 222 of the ball core 22 can be first installed into the first connecting hole 2111, and its outer wall can be directly opposite to the limiting opening 2112. At this time, one end of the rod body 221 is exposed outside the first connecting hole 2111, and the second connecting hole 2121 of the shear sleeve 212 can be sleeved on the outside of one end of the rod body 221. At the same time, one end of the shear sleeve 212 is inserted into the first connecting hole 2111 and its outer wall is screwed to the inner wall of the first connecting hole 2111. At this time, the cutting hole 2122 is directly opposite to the connecting hole 224. The shear pin 24 is installed into the shear hole 2122 and fixed to the connecting hole 224 to complete the assembly of the inner tube assembly 21 and the ball core 22. At this time, the limiting block 23 and the ball seat 2 can be installed into the outer tube body 1 according to the above steps, that is, the assembly of the bottom ball seat of the packer is completed, which improves the convenience of product assembly, that is, improves the convenience of product use.

[0040] Among them, both ends of the inner wall of the first cylinder 11 are provided with a first internal thread 112, and the outer wall of the second cylinder 12 is provided with a first external thread 121. The second cylinder 12 is connected to the first internal thread 112 at one end of the first cylinder 11 through the first external thread 121. When in use, the first internal thread 112 at the other end of the first cylinder 12 can be used to connect the seal.

[0041] Preferably, the inner wall of the first barrel 11 is also provided with a connecting annular groove 113, which is arranged at one end of the inner wall of the first barrel 11 away from the inner barrel assembly 21, and is located between the two first internal threads 112. When in use, the connecting annular groove 113 can be used to install a pressure gauge to monitor the downhole pressure. In this way, there is no need to install a tool string such as a landing short circuit for installing a pressure gauge during work, thereby further improving the practicality of the product.

[0042] In summary, in this example, when the inner cylinder assembly 21 is subjected to axial thrust, the inner cylinder assembly 21 cannot be axially displaced under the restriction of the limit block 23. Similarly, under the restriction of the shear pin 24, the ball core 22 cannot be axially displaced. When the shear pin 24 is disconnected, the ball core loses the restriction of the shear pin 24, and the limit ring 222 can slide along the first connecting hole 2111 toward the second connecting hole 2121 to move away from the limit opening 2112, so that one end of the limit block 23 loses the abutment force of the limit ring 222, thereby falling into the first connecting hole 2111 through the limit opening 2112. At this time, the inner cylinder assembly 21 loses the restriction of the limit block 23 and can move axially along the outer cylinder body 1 and disengage. That is, through the cooperation of the outer cylinder body, the inner cylinder assembly, the ball core and the limit block, only shear screws of conventional size and quantity need to be used during use, so as to reduce the cumulative error value of the shear pin and ensure that the ball seat obtains a larger diameter to meet work requirements.

[0043] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A bottom ball seat of a packer, characterized in that: include: An outer cylinder (1), the outer cylinder (1) being provided with a limiting annular groove (13), the limiting annular groove (13) being arranged along the circumference of the inner wall of the outer cylinder (1); as well as The ball seat (2) is arranged in the outer cylinder body (1), and comprises an inner cylinder assembly (21) and a ball core (22); the inner cylinder assembly (21) is provided with a first connecting hole (2111) and a second connecting hole (2121) connected in sequence along the axial direction, and the inner diameter of the first connecting hole (2111) is larger than the inner diameter of the second connecting hole (2121); the ball core (22) comprises a rod body (221), and the outer diameter of the rod body (221) is smaller than the inner diameter of the second connecting hole (2121). The rod body (221) has a diameter, which is slidably disposed in the second communicating hole (2121), and one end of which is exposed in the first communicating hole (2111); a limiting ring (222) is provided on the outer wall ring of one end of the rod body (221); the limiting ring (222) is slidably disposed in the first communicating hole (2111), and its outer diameter is larger than that of the second communicating hole (2121); one end of the rod body (221) also has a ball entry hole (223), and the ball entry hole (223) is directly opposite to a port at one end of the first communicating hole (2111); The ball seat (2) further comprises a plurality of limit blocks (23) and a plurality of shear pins (24); a plurality of limit openings (2112) and a plurality of shear holes (2122) are respectively provided at two ends of the side wall of the inner cylinder assembly (21) along the circumferential direction; the plurality of limit openings (2112) are communicated with the first communication hole (2111) and are directly opposite to the limit ring groove (13); the limit blocks (23) are respectively arranged in the limit openings (2112); two ends of each limit block (23) respectively abut against the limit ring (222) and the limit ring groove (13); the plurality of shear holes (2122) are communicated with the second communication hole (2121); a plurality of connection holes (224) are provided at one end of the rod body (221) away from the limit ring (222) corresponding to the shear holes (2122); and the plurality of shear pins (24) are respectively arranged in the plurality of shear holes (2122) and fixedly connected to the connection holes (224).

2. The bottom ball seat of the packer according to claim 1, characterized in that: The ball entrance through hole (223) is arranged to penetrate the rod body (221) along the axial direction, and comprises a first ball entrance hole (2231) and a second ball entrance hole (2232), wherein the first ball entrance hole (2231) is located at one end of the rod body (221) close to the limiting ring (222), the inner diameter of the first ball entrance hole (2231) is larger than the inner diameter of the second ball entrance hole (2232), a first blocking inclined hole (2233) is connected between the first ball entrance hole (2231) and the second ball entrance hole (2232), and the inner diameter of the first blocking inclined hole (2233) gradually decreases from the first ball entrance hole (2231) to the second ball entrance hole (2232).

3. The bottom ball seat of the packer according to claim 2, characterized in that: One end of the inner cylinder assembly (21) further comprises an annular guide opening (2113), the annular guide opening (2113) being located at an end of the first connecting hole (2111) facing away from the second connecting hole (2121), and the inner diameter of the annular guide opening (2113) gradually decreases towards the second connecting hole (2121).

4. The bottom ball seat of the packer according to claim 3, characterized in that: The ball core (22) is further provided with a second oblique blocking hole (2234). The second oblique blocking hole (2234) is provided at one end of the limiting ring (222) facing the annular guide opening (2113), one end of which is directly opposite to the annular guide opening (2113), and the other end of which is connected to the first ball entrance hole (2231). The inner diameter of the second oblique blocking hole (2234) also gradually decreases toward the second ball entrance hole (2232), and its maximum inner diameter is equal to the minimum inner diameter of the annular guide opening (2113), and its minimum inner diameter is equal to the inner diameter of the first ball entrance hole (2231).

5. The bottom ball seat of the packer according to claim 3, characterized in that: The outer cylinder (1) comprises a first cylinder (11) and a second cylinder (12); the inner wall of the first cylinder (11) is provided with a step surface (111), the step surface (111) faces one end of the first cylinder (11); one end of the second cylinder (12) is arranged in the first cylinder (11) and is screwed to the first cylinder (11); one end of the second cylinder (12) is opposite to the step surface (111) and a limiting ring groove (13) is formed between the step surface (111) and the second cylinder (12).

6. The bottom ball seat of the packer according to claim 5, characterized in that: The step surface (111) is an inclined surface, and the second cylinder (12) is provided with a limiting inclined surface (122) corresponding to the step surface (111). The step surface (111) and the limiting inclined surface (122) cause the side walls of the limiting ring groove (13) to tilt outwards on both sides thereof. An extrusion inclined surface (231) is provided at the end of the limiting block (23) corresponding to the step surface (111) and the limiting inclined surface (122). One end of the limiting block (23) abuts against the inside of the limiting ring groove (13), and the extrusion inclined surface (231) abuts against the step surface (111) and the limiting inclined surface (122) respectively.

7. The bottom ball seat of the packer according to claim 4, characterized in that: The inner cylinder assembly (21) comprises an inner cylinder body (211) and a shear sleeve (212); the inner cylinder body (211) is arranged in the outer cylinder body (1); a first communication hole (2111) is arranged through both ends of the inner cylinder body (211); an annular guide opening (2113) is arranged at one end of the inner cylinder body (211); a plurality of limit openings (2112) are arranged circumferentially on one end of the side wall of the inner cylinder body (211) close to the annular guide opening (2113); one end of the shear sleeve (212) is arranged in one end of the first communication hole (2111) facing away from the annular guide opening (2113) and is screwed to the inner cylinder body (211); the second communication hole (2121) is arranged through both ends of the shear sleeve (212); and a plurality of shear holes (2122) are arranged circumferentially on the side wall of the other end of the shear sleeve (212).

8. The bottom ball seat of the packer according to claim 5, characterized in that: Both ends of the inner wall of the first cylinder (11) are provided with a first internal thread (112), and the outer wall of the second cylinder (12) is provided with a first external thread (121). The second cylinder (12) is connected to the first internal thread (112) at one end of the first cylinder (11) via the first external thread (121). When in use, the first internal thread (112) at the other end of the first cylinder (11) can be used to connect a packer.

9. The bottom ball seat of the packer according to claim 8, characterized in that: The inner wall of the first cylinder (11) is further provided with a connecting annular groove (113). The connecting annular groove (113) is provided at an end of the inner wall of the first cylinder (11) away from the inner cylinder assembly (21) and is located between the two first internal threads (112). When in use, the connecting annular groove (113) can be used to install a pressure gauge.

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