Lifting jack for coal mine hydraulic support and the hydraulic support

Abstract

The utility model relates to a kind of lifting jack for coal mine hydraulic support and the hydraulic support, lifting jack includes cylinder body, integrally-formed piston, guide sleeve.Integrally-formed piston can avoid the leakage phenomenon caused by the piston head and piston rod of split piston due to connection loosening or sealing failure, can guarantee the normal work of jack.Cylinder body one end opening, the other end is closed.Guide sleeve is connected in opening end.Piston is located in cylinder body, and its piston rod is stretched to cylinder body outside by guide sleeve, and the outer peripheral wall of piston head divides cylinder body into upper cavity and lower cavity.Piston is equipped with first passageway and second passageway, respectively to upper cavity and lower cavity.Upper cavity interface and lower cavity interface are embedded in piston rod outer end, and the projection angle range of two interface axes is 90 °-180 °.There is enough space between upper cavity interface and lower cavity interface, and the inlet and return liquid pipe of different joint types can be installed, which is beneficial to the joint diversification design of inlet and return liquid pipe.

Description

Technical Field

[0001] This utility model relates to the field of coal mining equipment technology, and in particular to a lifting jack for a coal mine hydraulic support and the hydraulic support itself. Background Technology

[0002] In coal mining faces, the floor conditions are complex and variable. Due to factors such as geological structure and hydrogeological conditions, the floor is often relatively soft and is frequently soaked in water. Under these circumstances, the hydraulic support base is prone to sinking or bottoming out during the hydraulic support relocation process, affecting the normal forward movement of the hydraulic support.

[0003] The main function of the bottom lifting jack is to prevent the base from sinking, or to lift the base of the hydraulic support after it has sunk, so that the hydraulic support can be moved forward.

[0004] Jacks can be classified into externally inlet jacks and internally inlet jacks according to their fluid inlet and outlet methods. Traditional jacks consist of a cylinder, piston rod, piston head, and guide sleeve.

[0005] Externally inlet jacks typically have a connector welded to the cylinder body, along with an inlet assembly for hydraulic oil input. With prolonged use, this design can easily lead to damage or weld leaks in the inlet assembly and connector, causing a drop in hydraulic system pressure, affecting the jack's normal operation, and even potentially resulting in safety accidents.

[0006] Existing jacks use a split piston design, consisting of a piston rod and a piston head. The piston head and piston rod are typically connected by threads or sealed with a retaining ring. During long-term use, problems can easily arise at the connection between the piston head and piston rod. For threaded connections, the threads may gradually loosen, leading to leakage. Similarly, with retaining ring seals, the retaining rings can age and deform over time, causing seal failure and leakage. Leakage can destabilize the hydraulic system inside the jack, resulting in vibration and shaking during operation. This not only poses safety hazards to workers but also disrupts mining operations.

[0007] The upper and lower inlet ports of an internal liquid-inlet jack are typically located on the same platform on the same side of the piston rod head. While this simplifies the structure, the limited space on the same side of the piston rod head restricts the diverse design of the inlet and return pipes, making it difficult to accommodate different types of inlet and return pipes. Utility Model Content

[0008] (a) Technical problems to be solved

[0009] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a lifting jack for a hydraulic support in a coal mine and the hydraulic support thereon, which solves the technical problems of easy leakage when the existing jack uses an external liquid inlet component or a split piston, and the poor adaptability of the upper and lower liquid inlet interfaces to different types of liquid inlet and return pipes.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0012] In a first aspect, this utility model provides a lifting jack for a hydraulic support in a coal mine, comprising a cylinder, an integrally formed piston, and a guide sleeve; one end of the cylinder is open, and the other end is closed; the guide sleeve is detachably connected to one end of the cylinder opening; the piston is slidably embedded in the cylinder and its piston rod extends out of the cylinder from the guide sleeve, the outer peripheral wall of the piston head of the piston contacts the inner wall of the cylinder to divide the cylinder into an upper chamber and a lower chamber; the piston is provided with a first channel leading to the upper chamber and a second channel leading to the lower chamber, and the upper chamber interface and the lower chamber interface, which are respectively connected to the first channel and the second channel, are embedded at one end of the piston rod located outside the cylinder, and the angle between the projections of the axes of the upper chamber interface and the lower chamber interface in a plane perpendicular to the piston rod is in the range of 90°-180°.

[0013] Optionally, the first channel includes an axial section, a first radial section, and a second radial section. The outer ends of the first and second radial sections both penetrate the outer wall of the piston rod. The axial section connects the inner ends of the first and second radial sections. A third channel is provided inside the piston. The third channel and the axial section are integrally formed in one process. The third channel penetrates the bottom surface of the piston head. A sealing assembly is provided inside the third channel.

[0014] Optionally, the sealing assembly includes a sealing plug embedded in the third channel and a threaded plug threadedly connected to the third channel; the threaded plug presses against the outside of the sealing plug.

[0015] Optionally, the outer end of the piston rod is provided with a pin hole in a direction perpendicular to its axis; the upper cavity interface and the lower cavity interface are located between the guide sleeve and the pin hole, and the distance between the upper cavity interface and the lower cavity interface and the guide sleeve and the pin hole is greater than or equal to 20mm.

[0016] Optionally, two guide rings are respectively fitted on the inner peripheral wall of the guide sleeve and the outer peripheral wall of the piston head; sealing rings are respectively fitted on the inner peripheral wall of the guide sleeve and the outer peripheral wall of the piston head, and the sealing rings are located between two adjacent guide rings.

[0017] Optionally, the ratio of the piston head diameter to the piston rod diameter is greater than or equal to 1.11 and less than or equal to 1.43.

[0018] Optionally, it also includes a friction shoe; the friction shoe is fixedly fitted onto the closed end of the cylinder, and friction shoe ears are formed on both sides of it; high-strength wear-resistant welding wire is fixedly connected to both sides of each friction shoe ear.

[0019] Optionally, it also includes a trunnion and a connector; the trunnion is fixedly sleeved on the outer peripheral wall of the cylinder; the trunnion and the friction shoe lug are fixedly connected by the connector.

[0020] Secondly, this utility model provides a hydraulic support, including a support base and a pushing frame, the pushing frame being disposed in the middle of the support base, and also including a lifting jack for a coal mine hydraulic support; the support base includes a base body and a top frame, the top frame being fixedly connected to the base body; the pushing frame includes a pair of guide bars, each guide bar having a groove; a pair of friction shoe lugs are slidably engaged with the pair of grooves, and the piston head is fixedly connected to the top frame.

[0021] (III) Beneficial Effects

[0022] The beneficial effects of this utility model are as follows: This utility model provides a lifting jack for a hydraulic support in a coal mine, comprising a cylinder body, an integrally formed piston, and a guide sleeve. One end of the cylinder body is open, and the other end is closed. The guide sleeve is detachably connected to the open end of the cylinder body. The piston is slidably embedded in the cylinder body, and its piston rod extends out of the cylinder body from the guide sleeve, allowing the piston to slide up and down along the axis of the cylinder body. The outer peripheral wall of the piston head contacts the inner wall of the cylinder body to divide the cylinder body into an upper chamber and a lower chamber. The up and down sliding of the piston is controlled by introducing hydraulic oil into the upper or lower chamber. Compared with a split piston, the integrally formed piston can avoid the leakage caused by loose connection or seal failure of the piston head and piston rod of the split piston, ensuring the normal operation of the jack, ensuring that the support base can be raised normally, and reducing safety hazards to workers. The piston has a first channel leading to the upper chamber and a second channel leading to the lower chamber. The upper chamber interface and lower chamber interface, which communicate with the first and second channels respectively, are embedded in the piston rod at one end located outside the cylinder body. The angle between the projections of the axes of the upper chamber interface and the lower chamber interface onto a plane perpendicular to the piston rod ranges from 90° to 180°. Sufficient space is provided between the upper and lower chamber interfaces to accommodate inlet and return pipes of different connector types, facilitating diverse connector designs for the inlet and return pipes. Attached Figure Description

[0023] Figure 1 This is a half-sectional schematic diagram of an embodiment of the lifting jack for a hydraulic support in a coal mine according to the present invention.

[0024] Figure 2 for Figure 1 A schematic cross-sectional view at NN;

[0025] Figure 3for Figure 1 A cross-sectional schematic diagram of the piston and sealing assembly in the image;

[0026] Figure 4 for Figure 3 An enlarged schematic diagram of the sealing assembly shown at point I in the middle;

[0027] Figure 5 This is a cross-sectional schematic diagram along the axial direction of the cylinder body of one embodiment of a lifting jack for a hydraulic support in a coal mine according to the present invention.

[0028] Figure 6 This is a schematic diagram of the base and lifting jack of one embodiment of a hydraulic support according to the present invention.

[0029] [Explanation of Labels in the Attached Image]

[0030] 1: Cylinder block; 11: Cylinder bottom; 12: Cylinder barrel; 13: Upper chamber; 14: Lower chamber;

[0031] 2: Piston; 2a: Piston rod; 2b: Piston head; 21: Upper chamber interface; 22: Lower chamber interface;

[0032] 23: First channel; 23a: Axial segment; 23b: First radial segment; 23c: Second radial segment;

[0033] 24: Second channel; 25: Third channel; 26: Pin hole;

[0034] 3: Guide sleeve;

[0035] 4: Sealing assembly; 41: Sealing plug; 42: Threaded plug;

[0036] 5: Guide ring;

[0037] 6: Sealing ring;

[0038] 7: Friction shoes; 71: Friction shoe lugs;

[0039] 8: Trunnion;

[0040] 9: Connectors;

[0041] 101: Top frame;

[0042] 102: Guide bar. Detailed Implementation

[0043] To better explain and facilitate understanding of this utility model, a detailed description of its specific embodiments is provided below with reference to the accompanying drawings. In this document, directional terms such as "upper," "lower," "left," "right," "front," and "rear" are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference.

[0044] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0045] Example 1:

[0046] Reference Figures 1-5 This embodiment provides a lifting jack for a hydraulic support in a coal mine, which includes a cylinder 1, a piston 2, a guide sleeve 3, a friction shoe 7, and a trunnion 8.

[0047] Reference Figure 5 The cylinder body 1 consists of a cylinder bottom 11 and a cylinder barrel 12. The cylinder barrel 12 is a cylindrical structure with openings at both ends. The cylinder bottom 11 is fixed to the lower end of the cylinder barrel 12 by welding, so that end forms a closed structure. The upper end of the cylinder body 1 remains open, and internal threads are machined on the inner circumferential wall of the open end.

[0048] Reference Figure 1 The guide sleeve 3 is detachably connected to the open end of the cylinder body 1. Specifically, the guide sleeve 3 is a rotating body made of metal. The guide sleeve 3 is threaded to the open end of the cylinder body 1. An external thread is provided on the outer peripheral wall of the guide sleeve 3, which engages with the internal thread on the inner peripheral wall of the open end of the cylinder body 1, connecting the guide sleeve 3 and the cylinder body 1 into a single unit. Furthermore, to further enhance the connection's strength, threaded holes are machined axially at both ends of the guide sleeve 3 and the open side of the cylinder body 1. Bolts pass through these threaded holes in the guide sleeve 3 and the cylinder body 1 to secure the threaded connection, thus preventing loosening due to vibration.

[0049] Reference Figure 1 and Figure 3 The piston 2 is integrally formed from the piston rod 2a and the piston head 2b. The piston 2 is slidably embedded in the cylinder 1, allowing it to slide up and down along the axis of the cylinder 1. The guide sleeve 3 is used to guide the sliding direction of the piston 2 within the cylinder 1, ensuring the straightness and stability of the piston 2 during sliding.

[0050] Specifically, the piston rod 2a extends upward from the guide sleeve 3 to the outside of the cylinder body 1. The top of the piston rod 2a is used to lift the front end of the support base to prevent the front end of the support base from sinking into the base plate and getting stuck, thus ensuring that the hydraulic support can move forward normally.

[0051] The outer peripheral wall of the piston head 2b contacts the inner wall of the cylinder 1 to divide the cylinder 1 into an upper chamber 13 and a lower chamber 14. When hydraulic oil enters the lower chamber 14, the piston head 2b is subjected to upward pressure, which pushes the piston rod 2a to move upward, causing the front end of the support base to lift up. When hydraulic oil enters the upper chamber 13, the piston head 2b is subjected to downward pressure, which pushes the piston rod 2a to move downward, causing the front end of the support base to drop down.

[0052] The piston 2 has a first channel 23 and a second channel 24, wherein the first channel 23 leads to the upper cavity 13 and the second channel 24 leads to the lower cavity 14. The piston rod 2a of the piston 2 is provided with an upper cavity interface 21 and a lower cavity interface 22 at one end located outside the cylinder body 1, wherein the upper cavity interface 21 is connected to the first channel 23 and the lower cavity interface 22 is connected to the second channel 24.

[0053] Specifically, the first channel 23 includes an axial segment 23a, a first radial segment 23b, and a second radial segment 23c. The outer ends of both the first radial segment 23b and the second radial segment 23c penetrate the outer wall of the piston rod 2a, and the second radial segment 23c communicates with the upper cavity 13. The axial segment 23a connects the inner ends of the first radial segment 23b and the second radial segment 23c.

[0054] Specifically, the axial segment 23a of the first channel 23 extends axially along the piston rod 2a, and its two ends extend to the inner ends of the first radial segment 23b and the second radial segment 23c, respectively. The second channel 24 includes an axial segment and a radial segment, with the outer end of the radial segment penetrating the outer wall of the piston rod 2a. The upper cavity interface 21 is embedded in the first radial segment 23b of the first channel 23, and the lower cavity interface 22 is embedded in the radial segment of the second channel 24. Furthermore, the upper cavity interface 21 communicates with the upper cavity 13 through the first channel 23, allowing hydraulic oil to flow from the upper cavity interface 21 into the first channel 23, and then from the first channel 23 into the upper cavity 13; the lower cavity interface 22 communicates with the lower cavity 14 through the second channel 24, allowing hydraulic oil to flow from the lower cavity interface 22 into the second channel 24, and then from the second channel 24 into the lower cavity 14.

[0055] In a specific embodiment, to ensure that hydraulic oil can enter the upper chamber and that there is sufficient space to guarantee the pushing and pulling force of the jack piston, the ratio of the diameter of the piston head 2b to the diameter of the piston rod 2a (the value of the diameter of the piston head 2b divided by the diameter of the piston rod 2a) is greater than or equal to 1.11. To reduce stress concentration at the transition between the piston head 2b and the piston rod 2a, the ratio of the diameter of the piston head 2b to the diameter of the piston rod 2a (the value of the diameter of the piston head 2b divided by the diameter of the piston rod 2a) is less than or equal to 1.43.

[0056] Optionally, in order to further reduce stress concentration, a fillet is formed at the transition between the piston head 2b and the piston rod 2a, with the fillet radius being R2-R5mm.

[0057] Furthermore, to facilitate diverse designs of the inlet and outlet pipe connectors, sufficient space is reserved at the upper cavity interface 21 and the lower cavity interface 22 to ensure that the two connectors do not interfere with each other during connection.

[0058] Specifically, the angle between the projections of the axes of the upper cavity interface 21 and the lower cavity interface 22 onto the plane perpendicular to the piston rod 2a is in the range of 90°-180°.

[0059] More specifically, the positional relationship between the upper cavity interface 21 and the lower cavity interface 22 on the piston rod 2a includes two types: one is that the upper cavity interface 21 and the lower cavity interface 22 are in the same plane, and their axes can intersect directly, with an included angle ranging from 90° to 180°; the other is that the upper cavity interface 21 and the lower cavity interface 22 are not in the same plane, that is, there is a height difference between the upper cavity interface 21 and the lower cavity interface 22 on the axis of the piston 2, and when their axes are projected into a plane perpendicular to the piston rod 2a, the projection lines obtained by the projections of the two intersect in that plane, with an included angle ranging from 90° to 180°.

[0060] A third channel 25 is provided inside the piston 2, and the third channel 25 extends axially along the piston head 2b. The third channel 25 and the axial section 23a are integral channels formed in one process. The third channel 25 penetrates the bottom surface of the piston head 2b, that is, the third channel 25 is connected to the lower cavity 14.

[0061] In order to isolate the third channel 25 from the lower cavity 14, a sealing component 4 is provided in the third channel 25.

[0062] Specifically, refer to Figure 4 The sealing assembly 4 includes a sealing plug 41 and a threaded plug 42. The sealing plug 41 is embedded in the third channel, and the threaded plug 42 is threadedly connected to the lower end of the third channel 25. The threaded plug 42 presses against the outside of the sealing plug 41 and is located below the sealing plug 41. The sealing plug 41 can be made of stainless steel, polytetrafluoroethylene, nitrile rubber, or a metal-rubber composite material. Preferably, the sealing plug 41 is made of a metal-rubber composite material, which combines the strength of metal and the elasticity of rubber, thus improving sealing reliability and extending service life.

[0063] More specifically, the lower end of the inner wall of the third channel 25 is a stepped hole, with the diameter of the lower end being larger than that of the upper end, so that the sealing plug 41 can be embedded in the lower end of the third channel 25, preventing the sealing plug 41 from being squeezed from the lower end of the third channel 25 to the upper end, and also facilitating the replacement of the sealing plug 41.

[0064] To improve the sealing performance between the threaded plug 42 and the third channel 25, a sealant is applied to the threaded connection between the threaded plug 42 and the third channel 25. The sealant is Loctite, which is used for sealing and preventing loosening.

[0065] To improve the sealing performance between the sealing plug 41 and the third channel 25, at least two sealing rings are fitted on the outer peripheral wall of the sealing plug 41, and the sealing rings abut against the inner peripheral wall of the third channel 25.

[0066] Furthermore, a pin hole 26 is provided through the outer end of the piston rod 2a in a direction perpendicular to its axis. The function of the pin hole 26 is to fix the support base and ensure that the support base remains stable during lifting and lowering. The upper cavity interface 21 and the lower cavity interface 22 are located between the guide sleeve 3 and the pin hole 26. In order to leave sufficient space for both in the axial direction of the piston rod 2a, the distances of the upper cavity interface 21 and the lower cavity interface 22 from the guide sleeve 3 and the pin hole 26 are both greater than or equal to 20mm. Specifically, the distance of the axis of the upper cavity interface 21 and the lower cavity interface 22 from the guide sleeve 3 is greater than or equal to 20mm, and the distance of the axis of the upper cavity interface 21 and the lower cavity interface 22 from the axis of the pin hole 26 is greater than or equal to 20mm.

[0067] Two guide rings 5 ​​are respectively fitted onto the inner circumferential wall of the guide sleeve 3 and the outer circumferential wall of the piston head 2b, resulting in better guiding effect. Sealing rings 6 are respectively fitted onto the inner circumferential wall of the guide sleeve 3 and the outer circumferential wall of the piston head 2b, with the sealing rings 6 located between two adjacent guide rings 5. Both the guide rings 5 ​​and the sealing rings 6 are made of wear-resistant material and are O-shaped. The guide rings 5 ​​on the outer circumferential wall of the guide sleeve 3 guide the piston rod 2a to move axially, reducing friction and wear between the piston rod 2a and the inner ring of the guide sleeve 3, thus extending its service life. The guide rings 5 ​​on the outer circumferential wall of the piston head 2b guide the piston head 2b to move axially along the cylinder 12, reducing friction and wear between the outer circumferential wall of the piston head 2b and the inner circumferential wall of the cylinder 12, thus extending the service life of the piston head 2b.

[0068] The friction shoe 7 is fixedly fitted onto the closed end of the cylinder 1. During use, the friction shoe 7 can protect the cylinder bottom 11 of the jack. Furthermore, friction shoe lugs 71 are formed on both sides of the friction shoe 7.

[0069] Furthermore, the trunnion 8 is fixedly sleeved on the outer peripheral wall of the cylinder 1, and the trunnion 8 is fixedly connected to the friction shoe lug 71 by a connector 9. Specifically, the connector 9 is a bolt. The friction shoe lug 71 has a stepped hole, and the trunnion 8 has lugs on both sides, with corresponding through holes on the lugs. The bolt passes through the stepped hole and the through hole to connect the nut, thereby fixing the trunnion 8, the cylinder 1, and the friction shoe 7 into a whole.

[0070] The friction shoe lugs 71 are slidably connected to the pushing frame. During operation of the lifting jack, friction occurs at the connection point between the sliding movement of the friction shoe lugs 71 and the pushing frame. To prevent wear and tear on the friction shoe lugs 71, high-strength wear-resistant welding wire is welded onto the friction surfaces on both the front and rear sides of each friction shoe lug 71. The high-strength wear-resistant welding wire increases the surface hardness of the friction shoe lugs 71 and prevents friction between the hydraulic support's pushing frame and the friction shoe lug body, thus extending its service life. Even if the high-strength wear-resistant welding wire wears out after long-term use, it can be repaired in a timely manner to extend the service life of the friction shoe lugs 71 and ensure the normal operation of the lifting jack.

[0071] Example 2:

[0072] Reference Figure 6 This embodiment provides a hydraulic support, which includes a support base and a pushing frame. The pushing frame is fixedly connected to the middle of the support base. It also includes a lifting jack for a coal mine hydraulic support according to Embodiment 1.

[0073] The support base includes a base body and a top frame 101, with the top frame 101 fixedly connected to the base body, forming an integral unit. The sliding frame includes a pair of guide bars 102, each guide bar 102 having a U-shaped groove. A pair of friction shoe lugs 71 are slidably engaged with the pair of U-shaped grooves, and the pair of friction shoe lugs 71 are slidably disposed within the pair of U-shaped grooves.

[0074] The portion of piston rod 2a located at the outer end of cylinder 1 is fixedly connected to the top frame 101. Specifically, the pin hole 26 on piston rod 2a mates with two corresponding connecting holes on top frame 101. The pin passes through the two connecting holes and pin hole 26 to fix the bottom lifting jack and top frame 101 together, ensuring that the bottom lifting jack can smoothly lift the support base.

[0075] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0076] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0077] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0078] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A lifting jack for hydraulic supports in coal mines, characterized in that, Includes cylinder body (1), one-piece piston (2), and guide sleeve (3); The cylinder (1) has an opening at one end and is closed at the other end; The guide sleeve (3) is detachably connected to one end of the opening of the cylinder body (1); The piston (2) is slidably embedded in the cylinder (1) and its piston rod (2a) extends out of the cylinder (1) from the guide sleeve (3). The outer peripheral wall of the piston head (2b) of the piston (2) contacts the inner wall of the cylinder (1) to divide the cylinder (1) into an upper chamber (13) and a lower chamber (14). The piston (2) is provided with a first channel (23) leading to the upper cavity (13) and a second channel (24) leading to the lower cavity (14). The upper cavity interface (21) and the lower cavity interface (22) communicating with the first channel (23) and the second channel (24) respectively are embedded in the piston rod (2a) of the piston (2) located at one end outside the cylinder (1). The angle between the projection of the axis of the upper cavity interface (21) and the lower cavity interface (22) in the plane perpendicular to the piston rod (2a) is 90°-180°.

2. The lifting jack for a coal mine hydraulic support as described in claim 1, characterized in that: The first channel (23) includes an axial section (23a), a first radial section (23b), and a second radial section (23c). The outer ends of the first radial section (23b) and the second radial section (23c) both penetrate the outer wall of the piston rod (2a). The axial section (23a) is connected between the inner ends of the first radial section (23b) and the second radial section (23c). The piston (2) has a third channel (25) inside. The third channel (25) and the axial section (23a) are integral channels formed in one process. The third channel (25) penetrates the bottom surface of the piston head (2b). A sealing assembly (4) is provided in the third channel (25).

3. The lifting jack for a coal mine hydraulic support as described in claim 2, characterized in that: The sealing assembly (4) includes a sealing plug (41) embedded in the third channel and a threaded plug (42) threadedly connected to the third channel. The threaded plug (42) presses against the outside of the sealing plug (41).

4. The lifting jack for a coal mine hydraulic support as described in claim 1, characterized in that: The outer end of the piston rod (2a) is provided with a pin hole (26) in a direction perpendicular to its axis. The upper cavity interface (21) and the lower cavity interface (22) are located between the guide sleeve (3) and the pin hole (26), and the distance between the upper cavity interface (21) and the lower cavity interface (22) and the guide sleeve (3) and the pin hole (26) is greater than or equal to 20mm.

5. A lifting jack for a coal mine hydraulic support as described in claim 1, characterized in that: Two guide rings (5) are respectively fitted on the inner peripheral wall of the guide sleeve (3) and the outer peripheral wall of the piston head (2b); Sealing rings (6) are respectively fitted on the inner peripheral wall of the guide sleeve (3) and the outer peripheral wall of the piston head (2b), and the sealing rings (6) are located between two adjacent guide rings (5).

6. The lifting jack for a hydraulic support in a coal mine as described in claim 1, characterized in that: The ratio of the diameter of the piston head (2b) to the diameter of the piston rod (2a) is greater than or equal to 1.11 and less than or equal to 1.

43.

7. The lifting jack for a hydraulic support in a coal mine as described in claim 1, characterized in that: Also includes friction shoes (7); The friction shoe (7) is fixedly sleeved on the closed end of the cylinder (1), and friction shoe ears (71) are formed on both sides of it. High-strength wear-resistant welding wire is fixedly connected to both sides of each friction shoe lug (71).

8. A lifting jack for a hydraulic support in a coal mine as described in claim 7, characterized in that: It also includes trunnion (8) and connector (9); The trunnion (8) is fixedly sleeved on the outer peripheral wall of the cylinder (1); The trunnion (8) and the friction shoe lug (71) are fixedly connected by the connector (9).

9. A hydraulic support, comprising a support base and a pushing frame, wherein the pushing frame is disposed in the middle of the support base, characterized in that, It also includes a lifting jack for a coal mine hydraulic support as described in any one of claims 1-8; The support base includes a base body and a top frame (101), and the top frame (101) is fixedly connected to the base body; The pushing frame includes a pair of guide bars (102), each of which has a groove. The pair of friction shoe lugs (71) and the pair of sliding grooves are slidably engaged in a one-to-one correspondence, and the piston head (2b) is fixedly connected to the top frame (101).

Images