Three-telescopic stand column of hydraulic support

Abstract

The invention discloses a three-telescopic stand column of a hydraulic support, and relates to the technical field of hydraulic supports. The three-telescopic stand column of the hydraulic support comprises a first cylinder body, a second cylinder body, a third cylinder body, a movable column and a liquid supply assembly, the piston end of the second cylinder body is assembled in an inner cavity of the first cylinder body in a sliding mode, a first cavity and a second cavity are divided on the two axial sides of the second cylinder body, and the piston end of the third cylinder body is assembled in an inner cavity of the second cylinder body in a sliding mode; the piston end of the movable column is slidably assembled in an inner cavity of the third cylinder body, the liquid supply assembly comprises a first pipe, a second pipe and a one-way overflow valve, the first pipe is communicated with the first cavity, the second pipe is communicated with the second cavity, the input end of the one-way overflow valve is connected with the first pipe, and the output end of the one-way overflow valve is connected with the second pipe. The one-way overflow valve is used for being communicated with the second pipe when the pressure in the first pipe is larger than the first set pressure. The three-telescopic stand column of the hydraulic support has the pressure reducing and buffering effects and is good in impact resistance.

Description

Technical Field

[0001] This invention relates to the field of hydraulic support technology, specifically to a hydraulic support with a three-telescopic column. Background Technology

[0002] Faced with the geological conditions of irregularly sized and continuously changing coal seams underground, mining support is challenging and demanding. Three-stage telescopic hydraulic supports for coal mines are crucial equipment developed to address this problem. However, while ordinary three-stage telescopic supports achieve a large telescopic ratio, under high working resistance conditions, the pressure inside the middle cylinder is extremely high, making cylinder expansion prone to occur. Furthermore, due to their large deflection, their support safety performance is poor. Moreover, when the coal face is a thick coal seam with a hard roof, or when there is rock bursting, the impact load on the hydraulic support acts directly on the support column. Although ordinary three-stage telescopic supports are equipped with safety valves, the cylinder diameter of the first, second, and third stage cylinders decreases progressively. While each stage bears the same external pressure, the pressure intensity increases progressively. Since pressure is inversely proportional to the bearing area, the pressure inside the third stage cylinder becomes excessively high. Especially when the hydraulic support is frequently subjected to impact loads, it can easily cause serious incidents such as cylinder bursting and guide sleeves being ejected, posing a significant threat to equipment and personnel safety. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, this invention proposes a hydraulic support with a three-telescopic column, which has pressure reduction and buffering functions and good impact resistance.

[0005] The hydraulic support with three telescopic columns according to an embodiment of the present invention includes: The system comprises a first cylinder, a second cylinder, a third cylinder, and a movable column. The piston end of the second cylinder is slidably fitted into the inner cavity of the first cylinder and is axially separated into a first cavity and a second cavity. The piston end of the third cylinder is slidably fitted into the inner cavity of the second cylinder and is axially separated into a third cavity and a fourth cavity. The piston end of the movable column is slidably fitted into the inner cavity of the third cylinder and is axially separated into a fifth cavity and a sixth cavity. The second cylinder is provided with a first bottom valve for connecting the first cavity and the third cavity and a first flow channel for connecting the second cavity and the fourth cavity. The third cylinder is provided with a second bottom valve for connecting the third cavity and the fifth cavity and a second flow channel for connecting the fourth cavity and the sixth cavity. A liquid supply assembly includes a first pipe, a second pipe, and a one-way overflow valve. The first pipe is connected to a first chamber, and the second pipe is connected to a second chamber. The input end of the one-way overflow valve is connected to the first pipe, and the output end is connected to the second pipe. The one-way overflow valve is used to connect to the second pipe when the pressure in the first pipe is greater than a first set pressure.

[0006] The hydraulic support with three telescopic columns of this invention, by setting a one-way relief valve, when the column is impacted during use, the pressure in the first chamber increases, thereby making the pressure at the one-way relief valve position greater than the first set pressure. The first pipe and the second pipe are connected, that is, the first chamber and the second chamber are connected. The hydraulic oil in the first chamber can enter the second chamber through the first pipe and the second pipe, reducing the pressure in the first chamber. The impact kinetic energy is converted into the pressure energy of the hydraulic oil flow through the flow of hydraulic oil, thereby achieving the buffering of the impact and improving the impact resistance of the telescopic column.

[0007] In some embodiments, an integrated block is included, the integrated block including a third flow channel, a fourth flow channel and a connecting flow channel, the third flow channel being connected to the first pipe, the fourth flow channel being connected to the second pipe, the connecting flow channel connecting the third flow channel and the fourth flow channel, and the one-way overflow valve being disposed in the connecting flow channel.

[0008] In some embodiments, the integrated block is connected to a hydraulic control valve, which is connected to the third flow channel and the fourth flow channel respectively, and the hydraulic control valve is used to control the delivery of hydraulic oil to the third flow channel or the fourth flow channel.

[0009] In some embodiments, a connecting pipe is included, with its two ends connected to the first pipe and the second pipe, respectively, and the one-way overflow valve is disposed on the connecting pipe.

[0010] In some embodiments, a first seal is provided between the first cylinder and the second cylinder, a second seal is provided between the second cylinder and the third cylinder, and a third seal is provided between the movable column and the third cylinder.

[0011] In some embodiments, the system further includes a first balance bar, which is slidably mounted on the movable column. The piston end of the first balance bar and the inner cavity of the movable column are separated to form a seventh cavity on the side of the first balance bar away from the third cylinder. The first balance bar is provided with a fifth flow channel, which connects the fifth cavity and the seventh cavity.

[0012] In some embodiments, the cross-sectional diameter of the piston end of the first balance bar is larger than the cross-sectional diameter of the bar segment of the first balance bar, and the piston end of the first balance bar is axially stopped by the end of the movable column near the third cylinder.

[0013] In some embodiments, a second balance bar is further included, which is slidably mounted on the first balance bar. The piston end of the second balance bar and the inner cavity of the first balance bar are separated to form an eighth cavity on the side of the second balance bar away from the second cylinder. The second balance bar is provided with a sixth flow channel, which connects the third cavity and the eighth cavity.

[0014] In some embodiments, the cross-sectional diameter of the piston end of the second balance bar is larger than the cross-sectional diameter of the bar segment of the second balance bar, and the piston end of the second balance bar is axially stopped by the end of the first balance bar near the second cylinder or the third cylinder.

[0015] In some embodiments, a fourth seal is provided between the first balance bar and the movable column, and a fifth seal is provided between the second balance bar and the first balance bar. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the hydraulic support with three telescopic columns retracted according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the hydraulic support with three telescopic columns extended according to an embodiment of the present invention.

[0018] Figure label: First cylinder block 1; First chamber 11; Second cylinder 2; Third chamber 21; First flow channel 22; First bottom valve 23; Third cylinder block 3; Fifth chamber 31; Second flow channel 32; Second bottom valve 33; Movable column 4; Seventh cavity 41; Liquid supply assembly 5; first pipe 51; second pipe 52; one-way overflow valve 53; Integrated block 6; Third flow channel 61; Fourth flow channel 62; Connecting flow channel 63; Hydraulic control valve 7; First balance bar 8; Fifth flow channel 81; Eighth cavity 82; Second balance bar 9; sixth flow channel 91. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] like Figure 1 and Figure 2As shown, the hydraulic support with three telescopic columns in this embodiment includes a first cylinder 1, a second cylinder 2, a third cylinder 3, a movable column 4, and a fluid supply assembly 5. The piston end of the second cylinder 2 is slidably fitted into the inner cavity of the first cylinder 1, and is axially separated into a first cavity 11 and a second cavity. The piston end of the third cylinder 3 is slidably fitted into the inner cavity of the second cylinder 2, and is axially separated into a third cavity 21 and a fourth cavity. The piston end of the movable column 4 is slidably fitted into the inner cavity of the third cylinder 3, and is axially separated into a fifth cavity 31 and a sixth cavity. The second cylinder 2 is provided with a function to connect the first cavity 11 and the third cavity. The first bottom valve 23 of 21 and the first flow channel 22 connecting the second chamber and the fourth chamber are provided. The third cylinder body 3 is provided with a second bottom valve 33 for connecting the third chamber 21 and the fifth chamber 31 and a second flow channel 32 for connecting the fourth chamber and the sixth chamber. The liquid supply assembly 5 includes a first pipe 51, a second pipe 52 and a one-way overflow valve 53. The first pipe 51 is connected to the first chamber 11, and the second pipe 52 is connected to the second chamber. The input end of the one-way overflow valve 53 is connected to the first pipe 51 and the output end is connected to the second pipe 52. The one-way overflow valve 53 is used to connect the second pipe 52 when the pressure in the first pipe 51 is greater than the first set pressure.

[0021] In this embodiment of the invention, the hydraulic support with three telescopic columns, during the extension operation, the first pipe 51 supplies hydraulic oil, the second pipe 52 discharges hydraulic oil, and the hydraulic oil enters the first chamber 11, pushing the second cylinder 2, the third cylinder 3, and the movable column 4 to move and extend. When the second cylinder 2 moves to its limit position, the pressure in the first chamber 11 increases, and the first bottom valve 23 opens under pressure. The hydraulic oil enters the third chamber 21 through the first bottom valve 23 and pushes the third cylinder 3 and the movable column 4 to move and extend. When the third cylinder 3 moves to its limit position, the pressure in the third chamber 21 increases, and the second bottom valve 33 opens under pressure. The hydraulic oil enters the fifth chamber 31 through the second bottom valve 33 and pushes the movable column 4 to move and extend. When the movable column 4 extends to a set length and the telescopic column is under load, the first bottom valve 23 and the second bottom valve 33 close, separating the first chamber 11 and the third chamber 21, and separating the third chamber 21 and the fifth chamber 31, thereby improving the support force and reliability of the telescopic column under load. When the telescopic column is impacted, the pressure in the first chamber 11 increases, and the one-way relief valve 53 opens under the pressure. The hydraulic oil in the first chamber 11 reaches the second chamber through the first pipe 51 and the second pipe 52, which reduces the pressure in the first chamber 11. The pressure in the second chamber increases to drive the second cylinder 2 to move closer to the first cylinder 1, thus buffering the impact. At the same time, the hydraulic oil in the second chamber enters the fourth chamber through the first flow channel 22. The pressure in the fourth chamber increases to drive the third cylinder 3 to move closer to the first cylinder 1. The hydraulic oil in the fourth chamber enters the sixth chamber through the second flow channel 32. The pressure in the sixth chamber increases to drive the movable column 4 to move closer to the first cylinder 1, further reducing pressure and buffering the impact, thus improving the impact resistance of the telescopic column. During the retraction operation, hydraulic oil is discharged from the first pipe 51 and supplied to the second pipe 52. The hydraulic oil enters the second chamber through the second pipe 52 and then enters the fourth and sixth chambers through the first flow channel 22 and the second flow channel 32, respectively, to drive the second cylinder 2, the third cylinder 3 and the movable column 4 to move towards the first cylinder 1 for the retraction operation. The first bottom valve 23 and the second bottom valve 33 are opened, and the hydraulic oil in the first chamber 11, the third chamber 21 and the fifth chamber 31 is discharged through the first pipe 51.

[0022] In this embodiment of the invention, the hydraulic support with three telescopic columns, by setting a one-way relief valve 53, when the column is impacted during use, the pressure in the first chamber 11 increases, thereby making the pressure at the one-way relief valve 53 greater than the first set pressure. The first pipe 51 and the second pipe 52 are connected, that is, the first chamber 11 and the second chamber are connected. The hydraulic oil in the first chamber 11 can enter the second chamber through the first pipe 51 and the second pipe 52, reducing the pressure in the first chamber 11. The impact kinetic energy is converted into the pressure energy of the hydraulic oil flow through the flow of hydraulic oil, thereby achieving the buffering of the impact and improving the impact resistance of the telescopic column.

[0023] In some embodiments, such as Figure 1 and Figure 2 As shown, it includes an integrated block 6, which includes a third flow channel 61, a fourth flow channel 62 and a connecting flow channel 63. The third flow channel 61 is connected to the first pipe 51, the fourth flow channel 62 is connected to the second pipe 52, and the connecting flow channel 63 connects the third flow channel 61 and the fourth flow channel 62. A one-way overflow valve 53 is provided in the connecting flow channel.

[0024] In this embodiment, by setting up an integrated block 6, the first pipe 51, the second pipe 52 and the one-way overflow valve 53 are integrated together, which simplifies the structure and facilitates installation and maintenance. At the same time, the integrated block 6 realizes modular design, which facilitates production and use.

[0025] Specifically, the integrated block 6 is fixedly mounted on the first cylinder 1. One end of the first pipe 51 is connected to the first cavity 11 and the other end is connected to the third flow channel 61. One end of the second pipe 52 is connected to the second cavity and the other end is connected to the fourth flow channel 62. The third flow channel 61 and the fourth flow channel 62 are symmetrically arranged and form an L-shape. The connecting flow channel 63 connects the third flow channel 61 and the fourth flow channel 62. The one-way overflow valve 53 is installed in the flow channel.

[0026] In some embodiments, such as Figure 1 and Figure 2As shown, the integrated block 6 is connected to a hydraulic control valve 7, which is connected to the third flow channel 61 and the fourth flow channel 62 respectively. The hydraulic control valve 7 is used to control the supply of hydraulic oil to the third flow channel 61 or the fourth flow channel 62. By setting the hydraulic control valve 7, the supply of hydraulic oil to the third flow channel 61 and the fourth flow channel 62 can be controlled, which facilitates the control of the extension and retraction of the telescopic column, making operation convenient and installation easy. Optionally, the hydraulic control valve 7 is fixedly mounted on the integrated block 6.

[0027] In some embodiments, a connecting pipe is included, with its two ends connected to a first pipe 51 and a second pipe 52, respectively. A one-way overflow valve 53 is provided in the connecting pipe. By providing the connecting pipe, it is convenient to connect the first pipe 51 and the second pipe 52, and it is also convenient to set the one-way overflow valve 53 and make the adjustment reliable.

[0028] In some embodiments, a first seal is provided between the first cylinder 1 and the second cylinder 2, a second seal is provided between the second cylinder 2 and the third cylinder 3, and a third seal is provided between the movable column 4 and the third cylinder 3.

[0029] In this embodiment, by setting a first seal, a second seal, and a third seal, the sliding sealing between the first cylinder 1 and the second cylinder 2, between the second cylinder 2 and the third cylinder 3, and between the movable column 4 and the third cylinder 3 is improved, thereby improving the reliability and stability of the telescopic column during operation and further enhancing its impact resistance.

[0030] Specifically, the piston end of the second cylinder 2 is provided with a first mating groove extending circumferentially, the first seal is a sealing ring, the first seal is fitted in the first mating groove and adheres to the inner wall of the first cylinder 1, the piston end of the third cylinder 3 is provided with a second mating groove extending circumferentially, the second seal is a sealing ring, the second seal is fitted in the second mating groove and adheres to the inner wall of the second cylinder 2, and the piston end of the movable column 4 is provided with a third mating groove extending circumferentially, the third seal is a sealing ring, the third seal is fitted in the third mating groove and adheres to the inner wall of the third cylinder 3.

[0031] In some embodiments, such as Figure 1 and Figure 2 As shown, it also includes a first balance bar 8, which is slidably mounted on the movable column 4. The piston end of the first balance bar 8 and the inner cavity of the movable column 4 are separated to form a seventh cavity 41 on the side of the first balance bar 8 away from the third cylinder 3. A fifth flow channel 81 is provided on the first balance bar 8, which connects the fifth cavity 31 and the seventh cavity 41.

[0032] In this embodiment, a seventh cavity 41 is formed in the movable column 4 by the first balance bar 8. The hydraulic oil in the fifth cavity 31 can enter the seventh cavity 41 through the fifth flow channel 81. When the telescopic column is impacted, the total pressure-bearing area in the third cylinder 3 is the sum of the surface areas of the fifth cavity 31 and the seventh cavity 41. Under the same impact force, compared with the case where the first balance bar 8 is not set, the total pressure-bearing area increases, thereby reducing the pressure in the third cylinder 3, realizing the decompression of the third cylinder 3, reducing or avoiding events such as cylinder explosion in the third cylinder 3, and improving the impact resistance of the third cylinder 3.

[0033] In some embodiments, such as Figure 1 and Figure 2 As shown, the cross-sectional diameter of the piston end of the first balance bar 8 is larger than the cross-sectional diameter of the rod segment of the first balance bar 8, and the piston end of the first balance bar 8 and the end of the movable column 4 near the third cylinder 3 are axially stopped.

[0034] In this embodiment, by setting the cross-sectional diameter of the piston end of the first balance bar 8 to be larger than the cross-sectional diameter of the rod segment of the first balance bar 8, when the telescopic column is under load, the first balance bar 8 is subjected to the hydraulic pressure in the seventh chamber 41, and the rod segment of the first balance bar 8 is attached to the bottom of the third cylinder 3, thereby further improving the impact resistance of the third cylinder 3.

[0035] In some embodiments, such as Figure 1 and Figure 2 As shown, it also includes a second balance bar 9, which is slidably mounted on the first balance bar 8. The piston end of the second balance bar 9 and the inner cavity of the first balance bar 8 are separated to form an eighth cavity 82 on the side of the second balance bar 9 away from the second cylinder 2. The second balance bar 9 is provided with a sixth flow channel 91, which connects the third cavity 21 and the eighth cavity 82.

[0036] In this embodiment, the second balance bar 9 forms an eighth cavity 82 within the first balance bar 8. The hydraulic oil in the third cavity 21 can enter the eighth cavity 82 through the sixth flow channel 91. When the telescopic column is impacted, the total pressure-bearing area in the second cylinder 2 is the sum of the surface areas of the third cavity 21 and the eighth cavity 82. Under the same impact force, compared with the case where the second balance bar 9 is not set, the total pressure-bearing area increases, thereby reducing the pressure in the second cylinder 2, realizing the decompression of the second cylinder 2, reducing or avoiding events such as cylinder explosion in the second cylinder 2, and improving the impact resistance of the second cylinder 2.

[0037] In some embodiments, such as Figure 1 and Figure 2 As shown, the cross-sectional diameter of the piston end of the second balance bar 9 is larger than the cross-sectional diameter of the rod segment of the second balance bar 9, and the piston end of the second balance bar 9 is axially stopped by the end of the first balance bar 8 near the second cylinder 2 or the third cylinder 3.

[0038] In this embodiment, by setting the cross-sectional diameter of the piston end of the second balance bar 9 to be larger than the cross-sectional diameter of the rod segment of the second balance bar 9, when the telescopic column is under load, the second balance bar 9 is subjected to the hydraulic pressure in the eighth chamber 82, and the rod segment of the second balance bar 9 is attached to the bottom of the second cylinder 2, thereby further improving the impact resistance of the second cylinder 2.

[0039] In some embodiments, a fourth seal is provided between the first balance bar 8 and the movable column 4, and a fifth seal is provided between the second balance bar 9 and the first balance bar 8.

[0040] In this embodiment, by setting a fourth and a fifth sealing element, the sliding sealing between the first balance bar 8 and the movable column 4, as well as between the second balance bar 9 and the first balance bar 8, is improved, thereby improving the reliability and stability of the first balance bar 8 and the second parallel bar during operation, and further improving the impact resistance.

[0041] Specifically, the piston end of the first balance bar 8 is provided with a fourth mating groove extending circumferentially, the fourth seal is a sealing ring, the fourth seal is fitted in the fourth mating groove and adheres to the inner wall of the movable column 4, and the piston end of the second balance bar 9 is provided with a fifth mating groove extending circumferentially, the fifth seal is a sealing ring, the fifth seal is fitted in the fifth mating groove and adheres to the inner wall of the first balance bar 8.

[0042] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] Furthermore, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," 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, an electrical connection, or a connection that allows communication between them; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] In this invention, 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," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0047] 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 changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic support three-retraction stand column, characterized in that, The application relates to a hydraulic cylinder assembly. The hydraulic cylinder assembly comprises a first cylinder, a second cylinder, a third cylinder and a movable column, the piston end of the second cylinder is slidingly assembled in the inner cavity of the first cylinder and is separated into a first cavity and a second cavity on the two axial sides, the piston end of the third cylinder is slidingly assembled in the inner cavity of the second cylinder and is separated into a third cavity and a fourth cavity on the two axial sides, the piston end of the movable column is slidingly assembled in the inner cavity of the third cylinder and is separated into a fifth cavity and a sixth cavity on the two axial sides, the second cylinder is provided with a first bottom valve for connecting the first cavity and the third cavity and a first flow channel for connecting the second cavity and the fourth cavity, and the third cylinder is provided with a second bottom valve for connecting the third cavity and the fifth cavity and a second flow channel for connecting the fourth cavity and the sixth cavity. The hydraulic cylinder assembly further comprises a liquid supply assembly, the liquid supply assembly comprises a first pipe, a second pipe and a one-way overflow valve, the first pipe is connected with the first cavity, the second pipe is connected with the second cavity, the input end of the one-way overflow valve is connected with the first pipe and the output end is connected with the second pipe, and the one-way overflow valve is used for connecting the second pipe when the pressure in the first pipe is greater than a first set pressure.

2. The hydraulic support three-retractable stand column according to claim 1, characterized in that, The hydraulic cylinder assembly further comprises an integrated block, the integrated block comprises a third flow channel, a fourth flow channel and a connecting flow channel, the third flow channel is connected with the first pipe, the fourth flow channel is connected with the second pipe, the connecting flow channel connects the third flow channel and the fourth flow channel, and the one-way overflow valve is arranged in the connecting flow channel.

3. The hydraulic support three-retractable stand column according to claim 2, characterized in that, The integrated block is connected with a hydraulic control valve, the hydraulic control valve is connected with the third flow channel and the fourth flow channel respectively, and the hydraulic control valve is used for controlling the delivery of hydraulic oil to the third flow channel or the fourth flow channel.

4. The hydraulic support three-retractable stand column according to claim 1, characterized in that, The hydraulic cylinder assembly further comprises a connecting pipe, the two ends of the connecting pipe are connected with the first pipe and the second pipe respectively, and the one-way overflow valve is arranged in the connecting pipe.

5. The hydraulic support three-retractable stand column according to claim 1, characterized in that, The first seal is arranged between the first cylinder and the second cylinder, the second seal is arranged between the second cylinder and the third cylinder, and the third seal is arranged between the movable column and the third cylinder.

6. The hydraulic support three-retractable stand column according to any one of claims 1-5, characterized in that, The hydraulic cylinder assembly further comprises a first balance rod, the first balance rod is slidingly assembled in the movable column, the piston end of the first balance rod is separated from the inner cavity of the movable column on the side of the first balance rod away from the third cylinder to form a seventh cavity, and a fifth flow channel is arranged on the first balance rod and is used for connecting the fifth cavity and the seventh cavity.

7. The hydraulic support three-retractable column according to claim 6, characterized in that, The cross-sectional diameter of the piston end of the first balance rod is greater than the cross-sectional diameter of the rod segment of the first balance rod, and the piston end of the first balance rod is in abutting fit with the end of the movable column close to the third cylinder in the axial direction.

8. The hydraulic support three-retractable stand column according to claim 6, characterized in that, The hydraulic cylinder assembly further comprises a second balance rod, the second balance rod is slidingly assembled in the first balance rod, the piston end of the second balance rod is separated from the inner cavity of the first balance rod on the side of the second balance rod away from the second cylinder to form an eighth cavity, and a sixth flow channel is arranged on the second balance rod and is used for connecting the third cavity and the eighth cavity.

9. The hydraulic support three-retractable stand column according to claim 8, characterized in that, The piston end of the second balance bar has a larger cross-sectional diameter than the rod section of the second balance bar, and the piston end of the second balance bar is in axial stopper cooperation with one end of the second cylinder body or the third cylinder body.

10. The hydraulic support three-retractable stand column according to claim 8, characterized in that, The fourth seal is arranged between the first balance bar and the movable column, and the fifth seal is arranged between the second balance bar and the first balance bar.

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